fly ash and eggshells

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/324476334

Deriving Luminescent Materials from Sea Shell Waste Chapter · April 2018

CITATIONS

READS

0

61

5 authors, including: Luyanda Lunga Noto

Sefako J Mofokeng

Korea Research Institute of Chemical Technology

University of South Africa

37 PUBLICATIONS 177 CITATIONS


SEE PROFILE

SEE PROFILE

Nolufundo Sintwa

Bakang Moses Mothudi



1 PUBLICATION 0 CITATIONS


SEE PROFILE

SEE PROFILE

Some of the authors of this publication are also working on these related projects:

Preparation of graphene thin films View project

relationship between exchange rate volatility and gold mining sector share prices in south africa View project

All content following this page was uploaded by Sefako J Mofokeng on 12 April 2018. The user has requested enhancement of the downloaded file.

Complimentary Contributor Copy


ENVIRONMENTAL REMEDIATION TECHNOLOGIES, REGULATIONS AND SAFETY

“WASTE-TO-PROFIT” (W-T-P) VALUE ADDED PRODUCTS TO GENERATE WEALTH FOR A SUSTAINABLE ECONOMY VOLUME 1

No part of this digital document may be reproduced, stored in a retrieval system or transmitted in any form or by any means. The publisher has taken reasonable care in the preparation of this digital document, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained herein. This digital document is sold with the clear understanding that the publisher is not engaged in rendering legal, medical or any other professional services.


ENVIRONMENTAL REMEDIATION TECHNOLOGIES, REGULATIONS AND SAFETY Additional books in this series can be found on Nova’s website under the Series tab.

Additional e-books in this series can be found on Nova’s website under the e-Books tab.


ENVIRONMENTAL REMEDIATION TECHNOLOGIES, REGULATIONS AND SAFETY

“WASTE-TO-PROFIT” (W-T-P) VALUE ADDED PRODUCTS TO GENERATE WEALTH FOR A SUSTAINABLE ECONOMY VOLUME 1

LINDA ZIKHONA LINGANISO EDITOR


Copyright © 2018 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. We have partnered with Copyright Clearance Center to make it easy for you to obtain permissions to reuse content from this publication. Simply navigate to this publication’s page on Nova’s website and locate the “Get Permission” button below the title description. This button is linked directly to the title’s permission page on copyright.com. Alternatively, you can visit copyright.com and search by title, ISBN, or ISSN. For further questions about using the service on copyright.com, please contact: Copyright Clearance Center Phone: +1-(978) 750-8400 Fax: +1-(978) 750-4470 E-mail: [email protected]. NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers’ use of, or reliance upon, this material. Any parts of this book based on government reports are so indicated and copyright is claimed for those parts to the extent applicable to compilations of such works. Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter covered herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. Additional color graphics may be available in the e-book version of this book.

Library of Congress Cataloging-in-Publication Data ISBN: HERRN

Published by Nova Science Publishers, Inc. † New York


CONTENTS Preface Chapter 1

Chapter 2

vii From Waste to Biogas: Current Status, Opportunities, Barriers & Policy Implications Sarah G. Mungodla, Linda Z. Linganiso, Ella C. Linganiso, Tshwafo E. Motaung and Sandile P. Songca Transforming Construction and Demolition Wastes into Aggregates in Concrete Materials Samson Mohomane, Linda Z. Linganiso, Ella C. Linganiso, Tshwafo E. Motaung and Sandile P. Songca

Chapter 3

Deriving Luminescent Materials from Sea Shell Waste Luyanda L. Noto, Sefako J. Mofokeng, Nolufundo Sintwa, Mokgaotsa J. Mochane and Bakang M. Mothudi

Chapter 4

From Garbage to High Temperature Applications: Fly Ash and Eggshells Mokgaotsa J. Mochane, Teboho C. Mokhena, Luyanda L. Noto, Tshwafo E. Motaung, Thandi P. Gumede and Mary T. Motloung

Chapter 5

Chapter 6

Organic Waste Converted into Energy Producing and Storing Systems Fokotsa V. Molefe, Luyanda L. Noto, Mduduzi Mbongo, Mokgaotsa J. Mochane and Mokhotjwa S. Dhlamini Maize Stalk (Corn Stover) to Valuable Products Asanda Mtibe, Thabang H. Mokhothu and Linda Z. Linganiso


1

19

39

61

83

107

vi

Contents

Chapter 7

Softwood and Hardwood to Manufacturing Production Linda Z. Linganiso, Amanda Phungula, Ella C. Linganiso, Tshwafo E. Motaung and Sandile P. Songca

135

Chapter 8

Recycling of Plastic Materials Teboho C. Mokhena and Mokgaotsa J. Mochane

159

Chapter 9

The Application of Fly Ash as Industrial Waste Material in Building Construction Industries Samson Mohomane, Linda Z. Linganiso, Ella C. Linganiso, Tshwafo E. Motaung and Sandile P. Songca

Chapter 10

Bioplastics: From the Landfill to the Market Sudhakar Muniyasamy, Osei Ofosu, Linda Z. Linganiso and Tshwafo E. Motaung

Chapter 11

Transforming Fishery Waste into Chitin and Chitin Based Materials Teboho C. Mokhena and Mokgaotsa J. Mochane

181

203

227

Chapter 12

Biogas Production from Maize Crop and Maize Wastes Linda Z. Linganiso, Amanda Phungula, Tshwafo E. Motaung and Sandile P. Songca

251

Chapter 13

Waste Brick Applications Tshwafo E. Motaung, Amanda Phungula and Linda Z. Linganiso

275

Chapter 14

Sugarcane Bagasse Waste Management Zimele Mzimela, M. J. Mochane and Tshwafo E. Motaung

293

Chapter 15

Polymer/Ground Tire Rubber Blends as an Alternative for Waste Tire Management Mokgaotsa J. Mochane, Teboho C. Mokhena, Luyanda L. Noto and Tshwafo E. Motaung

303

About the Editor

321

Index

323


PREFACE “Wherefore let him that thinketh he standeth take heed lest he fall.” 1 Corinthians 10:12 (KJV)

The fastest and unquestionable route to losing clients and the market share is to stop innovating. Pondering on strategies to take over market control, you will surely discover your formula going in, while failure will be sure to follow if you celebrate your successes for a long time without any novelty. Why not generate wealth from different waste streams available when it is possible to develop a business system for a sustainable industry? Innovative business empires will not only help you generate sustainable profit, but will skyrocket your name above all well-known entrepreneurs who have peculiar abilities to handle high impact projects in communities while protecting the environment at the same time. This book is designed to help venture capitalists know where to invest their money for maximum returns. Aside from this, entrepreneurs will find it useful as it guides readers to understand where investments should go based on the current status of bio-projects in South Africa and selected countries. The key drivers for Waste-to-Profit activities include raising environmental awareness, policies and regulations in places throughout selected countries including South Africa. This book highlights the current policies and regulations to fast track the development of new technologies for bio-projects in these countries; opportunities, barriers and policy implications are discussed extensively. Why not also help the academics, researchers and students translate research and development findings into something of value (perhaps, a product)? The days of basic research alone are gone. The time is nigh – if not already here – to learn to translate research and development findings into something of value, to generate revenues which are essential for economic development. Not only would this help the intellectuals develop new technologies/products to generate profit, but it will assertively assist the world to transition towards a knowledge economy, an economy where knowledge is the main engine for


viii

Linda Zikhona Linganiso

economic development. This book will identify gaps in the waste beneficiation projects value chain, to avoid performing research which is thirty years behind. Recent research and development on waste beneficiation is given extensively for the purpose of identifying the gaps and fast tracking R&D in South Africa as well as other selected countries, in order to develop a business system that will afford these countries a sustainable economy. Municipalities in different countries will learn to develop a strategy to add value to their different waste streams through value added products such as Biofuels, Bioplastics and Biobricks, to mention a few. Chapter 1 - This chapter focuses on the current status of biogas production in South Africa and selected countries. The focus is given to rural household and commercial scale biogas production from waste material. Previous research indicates that South Africa’s biogas production will continue to grow at a slow pace, due to failure in policy reconceptualization and lack of highly skilled human capital in the country. It was reported elsewhere that investors, government entities and funding institutions in South Africa invested substantial amount of money in biogas technologies but the fact that most entrepreneurs in South Africa failed to perform techno-economic viability studies before undertaking such big corporations remains a question. In South Africa right now, many commercial biogas plants are failing due to the lack of knowledge in biogas technologies, leading to very low investment returns. This remains an urgent issue which needs to be addressed. Based on these issues, it is concluded that in order to ensure an achievement of a successful biogas industry in South Africa, policies which are specific for biogas should be implemented. Furthermore, plant operators and waste management officers in the current legislation must be trained so that they are knowledgeable in the industry. Most importantly, South Africa must obtain advice, guidance and support from countries which are already advanced in the technology such as Germany, Sweden and the US, to mention a few. Chapter 2 - The construction industry is an important economic sector that has a large environmental impact in terms of large quantities of construction and demolition wastes (C&DW) which are generated. The impact is also due to higher proportion of mineral resources excavated from nature and substantial amount of greenhouse gases generated causing severe ecological challenges. There is also a severe shortage of natural aggregates (NA) for the production of new concrete materials, due to a boom in construction activities that are currently taking place worldwide. Recently, significant efforts have been made to the management of C&DW due to their negative impact on environment, economy and society. Recycling and reuse of C&DW is one such attempt which is done by reintroducing them as recycled aggregates (RA) in new concrete materials. Application of recycled aggregates constitutes a significant step towards a sustainable green construction and creates a new market opportunity to be exploited. Chapter 3 - Waste materials have a tendency to pollute our environment and make them appear dirty. If unattended, they may cause harm to the animals and people as


Preface

ix

witnessed in most South African regions. This prompts for South African researchers and scientists to discover innovative ways to manage waste effectively. The authors need to do much more value addition to waste generated, develop products locally, while developing a strong business case essential for economic growth in our country. To overcome the aforementioned challenges, they illustrate how sea shells can be utilised to advance the current research. In addition, in this chapter, the authors also demonstrate how sea shells can be used in the development of new products for industrial applications. The authors show how sea shells can be converted to CaO. Not only this, applications of CaO in ceramic industry, biodiesel production and luminescent materials are also given extensively. Though the latter is still at research level, it has showed ample potential to provide light with any connection to electricity. Chapter 4 - There has been a major problem encountered by large cities around the world with regard to waste management. Fly ash is the secondary product obtained when ground coal is fed into burners to generate power; it is the unburned part of carbon. Coal consists of metals such as boron, chromium, mercury and others, as a result fly ash may have the traces of these elements, therefore there is a potential for fly ash to cause groundwater pollution. It is also noted that a lot of fly ash is produced globally; for instance, Japan produced 7 million tons of ash annually for the past 7 years. The other industrial waste generation include eggshells, which are also regarded as animal by-product. Large quantities of eggshells are produced annually mainly from processing of eggs with more than 350 thousand tonnes of eggshells produced by European Countries alone. As a result, there is a need to employ fillers such as fly ash and eggshells in a beneficial way to produce useful products for various applications. This chapter will focus on the positive effects of waste fillers (fly ash and eggshells) in improving the flammability resistance of materials such as plastics for higher temperature applications. Flame retardant fillers have been widely used since 1970s. These materials have been employed as additives to agricultural, medicinal, consumer science, building materials, industries and sports respectively. Chapter 5 - Recycling of domestic and agricultural organic waste is a fresh and exciting concept which promises both economic growth and environmental benefits. The production of organic waste continues on a daily basis, from domestic food, animal waste and dead animals. They all pollute the environment and may harm the people. The South African government has put forward regulations to assist in managing organic waste, inclusive to the natural composting process. In this chapter, the authors list economic benefits emanating from organic waste converted into a few potential energy sources. Inclusive to the energy sources, is the thermal energy that may be extracted during the composing process, which may be used to heat water for showering or as a central heating system for warming houses during cold seasons. Fertilizers and graphene may be derived from organic waste. The earlier is derived from an industrially controlled composting process, and it is important in refreshing the soil for the next plantation. The latter is considered a marvel material of the 21st century, and it promises tremendous enhancement


x


of the solar efficiency, energy storage specific hosting capacity, just to mention a few. Not only will graphene be important in the energy sector, but in many more other applications, and a few is listed. Chapter 6 - This chapter presents a broad review on the recent advances in research and developments on maize stover. Maize stover, a by-product of maize, is abundantly available in South Africa. It is mainly used as a fertilizer and nutritive fodder for livestock while the remaining portion is left in the field after harvesting or dumped on dumping sites. Alternatively, the dumped maize stover end up being incinerated due to lack of space. Despite valuable properties of this material, there is no direct use and hence it is underutilized. However, population growth has resulted in increased amount of maize produced which has increased the volumes of agricultural waste generated in landfills. This calls out for a proper waste management strategy to be established in South Africa. As a result, South African waste management sector has put a systematic approach in place to reduce, recover, recycle and re-use agro-wastes generated in landfills as well as to improve the handling of waste materials. Furthermore, there is a necessity to do much more value addition to maize stover for other applications in industries. This will contribute to the development of sustainable products while supporting South Africa’s bioeconomy strategy. Some of the value added products include: high performance chemicals extracted from maize stover, green composites, biogas and biofuels respectively. In this chapter, recent research and development on maize stover, challenges associated with developing products from maize fibers and future prospects as well as government initiatives will be discussed. Chapter 7 - Manufacturing of high performance engineering materials from renewable resources is one of ambitious goals currently being pursued by researchers all over the world. The ecological benefits of renewable resources are obviously environmental friendlyness, valuability and the fact that they do not cause health problems. Fibers extracted from softwood and hardwood have already established a track record as reinforcing materials in automotive parts and spreading up with high growth rate to packaging, contraction and household utility based small industries because of their light weight, low cost, and environmental friendly nature. In recent years, a special concern has been manifested towards “green composites.” Some of the efforts have been based on the use of new waste sources, with the aim to obtain biologically active compounds which can be applied in different fields and applications. The traditional use of softwood and hardwood are in building sector. One biggest advantage of using wood as a building material is that it is remarkable strong in relation to its weight and it provides good insulation from the cold. Wood is also highly machinable and can be fabricated into all kinds of shapes and sizes to fit practically any construction need which carries the lowest carbon footprint of comparable building material. In this chapter, investigation of the potential of grain by-products such as softwood and hardwood as reinforcement in plastic


Preface

xi

matrices for potential applications in different sectors is reviewed together with recent research and development pertaining to these wood materials. Chapter 8 - Plastics have been used in a number of industries and other sectors such as transportation, construction, health care, food products, telecommunications and consumer products to mention a few. The intense focus to plastic materials was found to be due to many positive features these plastic materials possess such as lightweight and low cost, to mention a few. The plastics production rate is growing rapidly due to growing population which accelerates the consumption rate. The recovery and recycling remains the most unsustainable process which needs more attention worldwide. It was recently recognized that the disposal of plastic requires other means than traditional approaches (dumping in the landfill sites). This is one of the major problems of the millennia that needs urgent action to change the culture and governmental regulations towards the plastic disposal. Some of the new approaches such as reduction of plastic production, recycling, and producing viable cheaper products from waste plastics are discussed in this chapter. The challenges and opportunities associated with plastic recycling have also been addressed. Chapter 9 - The increasing interest in sustainable awareness has created the need for the construction industry to develop construction materials with the appropriate utilization of wastes in a manner that meets our economic, social and cultural needs. The interest is also due to ever increasing scarcity of landfill space, accumulation of unmanaged wastes and awareness to protect the environment. The use of wastes as brick material is a sustainable solution to solid waste management and provides alternative raw materials and an additional source of revenue. The application of industrial wastes such as fly ash to develop construction bricks offers an attractive alternative to its disposal, and has a number of advantages including low cost, abundant raw material availability and lower degree of industrialization. Fly ash is a by-product of the combustion of pulverized coal in thermal power plants gathered by electrostatic precipitators from the combustion gases before they are discharged into the atmosphere. This waste is a potential source of material with pozzolanic reactivity and its application in brick manufacturing will minimize the volume of waste in the landfill sites. For these reasons, this chapter will focus on the utilization of fly ash on developing environmentally friendly, low-cost and lightweight bricks as a response to environmental and economic concerns. The current worldwide production of construction bricks is about 1.391 trillion units per year, and the demand for bricks is constantly rising. Chapter 10 - The present chapter is focussed on the development of environmentally friendly materials (biodegradable plastics) from recycled petroleum based plastics. Petroleum based plastics are collected from the landfill sites, washed, separated and subjected to a cutter for size reduction. After this, a hot melt extrusion is used to mix them with additives extracted from agricultural residues such as sugarcane bagasse or maize stalk to induce biodegradation. Environmentally biodegradable materials are promising green materials as they degrade at landfill in less than a year. However, it is necessary to


xii


address the environmental biodegradability of environmentally friendly materials in order to meet various commercial and environmental needs for their sustainable growth. In this chapter, the authors discussed recycling of petroleum based plastics from the landfill sites and conversion to environmentally friendly plastics. Applications of sustainable materials are also discussed. Chapter 11 - Chitin is the second most abundant natural polymer, extracted from exoskeleton of crustaceans, fungal mycelia and mushroom wastes. More than 1000 metric tons/year of chitin can be generated from mushroom wastes, while the crustaceans produce more than 10 million tons with only 10% used for commercial applications. This has resulted to more of these materials ending up in landfills and causing environmental problem due to their slow degradation rate. Chitin has unique valuable properties that can be explored to prepare different materials for various applications. This includes non-toxic, antibiotic, biocompatibility, and biodegradability as well as haemostatic behavior and heavy metal ions chelation. In this chapter the success of chitin and challenges with regard to its recyclability and production of value added products are discussed. In addition, the mile stone reached in the preparation of chitin derivatives their success, challenges and applications have also been addressed. Chapter 12 - After harvesting, vast amount of agricultural biomass is burnt in the open field annually. The burning of biomass residues releases greenhouse gases which lead to climate change and global warming. In addition, there is a worldwide increase in the demand for energy crops for the purpose of biogas production. A maximum methane yield per hectare should be achieved with energy crops. In this chapter, a summary of researches involving maize waste together with maize crops utilization in the production of biogas is discussed. The climate, location, maize diversity, harvesting time, harvesting technology, conservation, chopping, additives, environmental conditions, fermentation technology, substrate composition and plant management are all factors that must be considered when both maize crops and maize residues are used for biogas production. Maize crops as well as maize waste have been used extensively in biogas production by many and this chapter will focus on both maize crop and maize waste utilization in methane fermentation process (biogas production). Chapter 13 - Bricks are materials used worldwide in building and construction sector. In ancient times, bricks were made using clay by human hands and they were left to dry in the sun. Other types of bricks such as compressed earth brick (CEB) have been developed, which are more advantageous as compared to other types. While a building is being built, some bricks are broken and can no longer be used in that building, as a results, they are considered as “waste bricks”. The waste bricks are used to produce other useful products such as replacement of cement in mortar, aggregate in the manufacturing of paving blocks, pavement sub-base materials, etc. Waste bricks can also be used in the production of other new bricks, which can be used again in building and construction sectors. There are many other applications of waste bricks and this chapter focuses on them. It will also report on


Preface

xiii

regulations and policies of waste bricks and give highlights on the market structure and demand. Chapter 14 - Sugarcane bagasse is the fibrous matter that remains after sugarcane has been crushed to extract its juices during the production of sugar. It represents around 3040 wt. % of the waste materials. It is highly abundant in many countries like Brazil, South Africa, India, Peru and Australia. In 2008, South Africa alone produced 7.9 million tons of bagasse. It is estimated that 5.4 * 108 dry tons of sugarcane are processed each and every year globally. Generally, for every single ton of sugarcane, approximately 280 kg of sugarcane bagasse is generated. This material can be seen as either a waste, affecting the environment, or as a very useful resource when appropriate valorization techniques are implemented. Sugarcane bagasse is composed of, as the major components, lignin (approximately 23.5%), hemicelluloses (approximately 28.6%) and cellulose (around 48.3%), respectively. Due to its relatively low ash content (approximately 1.9%), it has the prospects of finding many applications in contrast to other agro-based residues. Basically, the chemical composition of sugarcane bagasse makes it superb for applications in the synthesis of composite materials that possess exceptional chemical and physical properties. Bagasse also has the added advantage of low fabricating costs and high quality green end materials. It has found applications in many sectors; it is converted into energy through combustion, especially in sugar industries, it is used in the production of activated carbon, in gasification, in the production of cellulosic ethanol, and in pulping, to mention but a few. Chapter 15 - The increase in the number of vehicles in the world generally results in a significant problem of used tires being disposed of in landfill sites. The increase in the number of waste rubber tires becomes a serious environmental challenge. Also, the burning and landfilling of tires is strictly forbidden in the country according to South African regulations. In other countries in the world, the waste tires have been used as fuel in cement kilns. However, this is not economically feasible since tires release greenhouse gases, leading to global warming and climate change. Different alternatives have been suggested to recycle tire rubber to add value to it through value added products but the large scale usage of these methods remain unfeasible due to high cost involved in implementation stages. One of the most promising emerging waste management approaches is the mechanical recycling of tires. The mechanical recycling of tires involves the grinding of tires as well as splitting the metal and rubber components. The grinding of tires, followed by the addition of ground tire rubber to polymer matrices seems to be the most viable method of doing much more value addition to waste tire to generate products which can bring financial returns. This approach also assist South African government to establish a proper waste management strategy and support the Department of Science and Technology’s Bio-economy strategy.



In: “Waste-to-Profit” (W-t-P) Editor: Linda Zikhona Linganiso

ISBN: 978-1-53613-235-9 © 2018 Nova Science Publishers, Inc.

Chapter 1

FROM WASTE TO BIOGAS: CURRENT STATUS, OPPORTUNITIES, BARRIERS & POLICY IMPLICATIONS Sarah G. Mungodla1,*, Linda Z. Linganiso1, Ella C. Linganiso2, Tshwafo E. Motaung1 and Sandile P. Songca1 1 2

Department of Chemistry, University of Zululand, KwaDlangezwa, South Africa Molecular Sciences institute, School of Chemistry, University of Witswatersrand, Johannesburg, South Africa

ABSTRACT This chapter focuses on the current status of biogas production in South Africa and selected countries. The focus is given to rural household and commercial scale biogas production from waste material. Previous research indicates that South Africa’s biogas production will continue to grow at a slow pace, due to failure in policy reconceptualization and lack of highly skilled human capital in the country. It was reported elsewhere that investors, government entities and funding institutions in South Africa invested substantial amount of money in biogas technologies but the fact that most entrepreneurs in South Africa failed to perform techno-economic viability studies before undertaking such big corporations remains a question. In South Africa right now, many commercial biogas plants are failing due to the lack of knowledge in biogas technologies, leading to very low investment returns. This remains an urgent issue which needs to be addressed. Based on these issues, it is concluded that in order to ensure an achievement of a successful biogas industry in South Africa, policies which are specific for biogas should be implemented. Furthermore, plant operators and waste management officers in the current legislation must be trained so that they are knowledgeable in the industry. Most importantly, South Africa *

Corresponding Author. Email: [email protected].


2

Sarah G. Mungodla, Linda Z. Linganiso, Ella C. Linganiso et al. must obtain advice, guidance and support from countries which are already advanced in the technology such as Germany, Sweden and the US, to mention a few.

Keywords: biogas production, policy, South Africa, waste

1. INTRODUCTION South African biogas production technology is agreeable at an infancy stage with about 38 commercial operation projects in place and nearly 1700 people employed directly by biogas industries [1]. The municipal waste sector has enormous energy potential, so there is no doubt that biogas production has a significant role, not only in economic growth but in waste management sector as a whole. Apart from this, biogas technology remains underdeveloped with common biogas technologies established in SA being small to medium biogas plants [2]. South Africa and other African countries still find it difficult to establish a proper waste management strategy and affordable household electricity. As a result, poverty prevails and unemployment rate continues to rise. The deployment of biogas could help solve the aforementioned struggles. South African waste management sector is addicted to landfilling due to low landfill gate cost and cheaper electricity when compared to the developed countries such as Germany [2, 3]. This attitude must change because there is now limited landfill space and the massive amount of waste generated in landfill produce large amounts of methane and other harmful gases which later induce global warming and climate change. In addition, as population, urbanization and industrialization increases in developing countries more waste is generated. South Africa produced approximately 108 million tons of waste in 2011, of this amount, 98 million tons were disposed of at landfills [4]. It was further highlighted that of this waste, 13% of municipal solid waste is organic waste [4]. It was also reported that 3 million tons of organic waste is generated per annum, 35% is recycled and the rest is sent to landfill. Also, 0.5 million tons of sewage sludge is landfilled per annum [4]. However, there are obvious advantages of biogas production from sewage sludge such as lowering pathogens in landfills. Other challenges which have resulted in low outputs are lack of policies/regulatory frame work that supports biogas grid facilitated by independent power producers outside the REIPPPP (Renewable energy independent power producer procurement program) [4, 5]. Countries such as Germany, USD, Japan, China, India and Brazil amongst others are fast passing in terms of biogas or bioethanol/diesel technologies. South African entrepreneurs are encouraged to partake in these undertakings as they are essential for energy security and will assist the country to transition towards bio-economy. In addition, in South Africa, the market for biogas production is still open for entrepreneurs and investors to do more value addition to waste while developing new products (green energy) for a sustainable economy.


From Waste to Biogas

3

1.1. General Policies and Legislations for Waste and Energy in South Africa 1.1.1. Energy Policies and Regulation in South Africa There are various policies, legislation and regulations which drive and influence the development of renewable energy in South Africa. Consequently, it is imperative for entrepreneurs to understand policies which govern biogas production in South Africa. For the content of this chapter, highlighted policies are only those relevant for biogas production from organic waste in South Africa. 1.1.2. Energy Policy White Paper, (1998) The white paper provides a broader and specific policy statement on what the government intends for the energy system as a whole. Its intent is to constitute a formal framework within which the energy sector will operate within broad national strategy for reconstruction and development. The white paper serves to bring more focus and direction to what is already achieved. The white paper also advocates for the broadening of energy supply mix, thus acknowledging the role of renewable energy technologies in the future energy development of the country. 1.1.3. White Paper on Integrated Pollution and Waste Management, (2000) The white paper provides methods for handling and dealing with waste. The focus of the white paper is to prevent pollution at the source so that harmful impact to the environment can be minimized and degraded environment can be rehabilitated. The integral part of the strategy is a proposal for the development of the waste management hierarchy which promotes reduce, reuse and recycle as priorities and landfill as last resort. It then, provides an excellent platform for the development of biogas from various waste streams. 1.1.4. Renewable Energy Strategy, (2003) The renewable energy strategy highlights a practical role for renewable energy sources in the South African energy supply matrix. The strategy further proposed a target for energy generation from renewable energy. Thus outlining a development plan for renewable energy sources. 1.1.5. Free Basic Alternative Energy Policy, (2007) The free basic alternative energy policy proposed the provision with financial resources for the acquisition of the alternative energy sources. It also creates a developmental opportunity for other energy sources including biogas. Municipalities are provided with financial resources for the procurement of alternative energy sources.


4

Sarah G. Mungodla, Linda Z. Linganiso, Ella C. Linganiso et al.

1.1.6. National Climate Change Policy White Paper, (2011) The white paper outlines that the most promising easing option for the country are primarily energy efficiency, demand side management, and increased investments in renewable energy flagship program. 1.1.7. Renewable Energy Fit in Tariff (REFIT) Phase 2, (2009) The renewable energy fit-it tariff, restricted the tariffs for the purchase of energy from renewable energy generators at specified prices, as part of the renewable energy independent power producers program. The second phase of the REFIT agreed on the price to be paid for energy generation from biogas. This opened a platform for negotiating the price for biogas energy producers. 1.1.8. The National Development Plan The national development plan is a long term economic strategy incorporating political and social objectives. The strategy proposed steps which aim to transform the country’s energy system and reduce greenhouse gas emissions. The development plan set target to procure 20 000MW of electricity from renewable energy.

1.2. Policies for Waste Management in South Africa 1.2.1. South Africa’s National Policy on the Thermal Treatment of General and Hazardous Waste, Gn. R. 777, (2009) The policy presents the government intent on thermal waste treatment as an acceptable waste management option for South African waste. It provides the framework for the implementation of thermal waste treatment technologies such as: 



The incineration of general and hazardous waste in dedicated incinerators or other high temperature thermal treatment technologies, including but not limited to pyrolysis and gasification for generation of electricity. The co-processing of selected general and hazardous waste as alternative fuels and raw materials for cement production [10].

1.2.2. The Integrated Resource Plan, (2011) This is a long term resource plan that provides a framework to supply South Africa’s power needs at the lowest cost. Municipality solid waste is enlisted as one of the potential source of renewable energy [10].



5

1.2.3. The National Waste Management Strategy (NWMS), (2012) The National Waste Management Strategy (NWMS) is a legislative requirement of the National Environmental Management: Waste Act, 2008 (Act No. 59 of 2008), the “Waste Act”. The purpose of the NWMS is to achieve the objects of the Waste Act. Organs of state and affected persons are obliged to give effect to the NWMS”. The waste management in South Africa faces challenges and the NWMS provides a plan to address them [10]. 1.2.4. Legislation Applicable to Working with Municipality The Municipal Systems Act, No. 32 of 2000 (MSA) governs municipalities when they improve, extend or upgrade a municipal service or establish a new municipal service that is currently outside the existing municipal finances, among other things [10]. The following Section, 78 step processes are taken before a municipality can partner with a private entity: 1. Assesses the different internal service delivery mechanisms, as well as the municipality’s capacity for implementing the different mechanisms. 2. Stipulates that a municipality may decide on an internal mechanism (based on the outcome of the Step 1, but may also explore the possibility of providing the service via an external mechanism. 3. Dictates the processes that must be followed in assessing the provision of the service via an external mechanism. 4. Stipulates that a municipality may decide on an appropriate internal or external service delivery mechanism, based on the results of the step study. 5. Stipulates that the application of Section 78 process must be aligned with other legislations.

1.3. Licenses for Biogas Technology Implementation 1.3.1. The Licensing Requirement of the Waste Water Treatment Works (WWTW) In the case of an existing, legally registered WWTW, the impact on the licenses and permits of introducing a biogas plant still has to be determined. Various laws must be taken into account, among others, the National Environmental Management Act and the National Water Act [10]. 1.3.2. Environmental Impact Assessment (EIA) The National Environmental Management Act (No. 107 of 1998) states that projects may be subject to a Basic Assessment or to Scoping and Environmental Impact Reporting, the latter often being referred to as a “Full EIA”. The choice between Basic Assessment and Full Environmental Impact Assessment (EIA) depends on the scale and design of the existing WWTW facility, on the scale and design of the biogas digester, and on the existing


6


licenses [11]. In EIA, procedure which ensures that environmental consequences of projects are identified and assessed before authorization is given.

Various Authorizations Waste Management License; Water Use License, Atmospheric Emission License; Land Use Planning Authorization; Major Hazard Installation Regulations may also be relevant. Electricity-Related Authorization While a generating license from NERSA is usually only required if the project sells the electricity into the national grid, biogas is an exception, Section 28 of the Gas Act No. 48 of 2001 stipulates that NERSA registers all small biogas projects not connected to the grid.

2. WASTE TO BIOGAS IN SOUTH AFRICA 2.1. Introduction

Figure 1. Waste management hierarchy, Source: Waste Act Made Easy - a user-friendly guide.

Figure 2. (Continued)


From Waste to Biogas most favoured option

7

prevention minimisation reuse recycling

least favoured option

energy recovery

disposal

Figure 2. Historic waste management hierarchy [12].

Even though South Africa has been developing policies and regulations for renewable energy framework as discussed above, the South African government fails to promote the waste management hierarchy illustrated in Figure 1. The implementation of significant components of the policy and laws are lacking. Moreover, the national waste management strategy is weakly implemented in this current climate. This is mainly due to limited government capacity. As a results, South Africa continues to follow the historic waste management strategy shown in Figure 2. This strategy was driven by access to freely available land, characterized by low density settlements and dry conditions with abundant supplies of coal. However, this can no longer prevail because currently there is a limited landfill space available to divert all of municipality, industrial and commercial waste. The country’s 90% landfill culture is no longer sustainable and South Africa is urgently and slowly taking up green technologies and thereby embracing a collection of new waste management methods and technologies. According to the National Waste Information Baseline Report, 2013 [4] of South Africa, the country produced approximately 108 million tons of waste in 2011, of this amount, 98 million tons were disposed of at landfills. Furthermore, even though the recycling industry has improved and is now a global business with international markets, only about 10% of solid waste is recycled [2]. Therefore, there is still a high demand for waste recycling and reduction in volumes of waste to landfill. More economical solutions to reduce waste disposal while providing energy in the large urban municipalities are in high demand. This suggests that the next imperative step South Africa must take is to produce biogas from biodegradable wastes, more especially taking advantage of massive amount of waste available in landfills. Future plans could be to produce bioethanol from methane, provided that investment, research and development in green technology improve. Currently, biogas production to generate electricity is a feasible option. If the new waste management strategy is well practiced, South African Department of Science and Technology (DST) estimates that by diverting waste away from landfill, the country could increase the revenues made in this sector by additional R17 billion/year [6].


8


2.2. South African Waste South African waste management sector is waste generating. In 2011, the country produced roughly 108 million tons of waste [4, 7]. Fifty-nine million tons was general waste; forty-eight million tons corresponded to unclassified waste whereas one million ton belonged to hazardous waste (Figure 3) [4]. Only 10% of waste generated in the country is recovered for reprocessing. It is also estimated that 65% of the classified waste (around 38 million tons) is classified as recyclable and therefore could theoretically be diverted from landfill for further recovery for reprocessing [7]. Most importantly, biogas commercial technologies are technically feasible in South Africa as 13% of municipal solid waste is organic waste [4]. It was also mentioned somewhere that million tons of organic waste are generated per annum, 35% is recycled and the rest which is 65% remains in landfill [2]. In addition, for biogas purpose, 0.5 million tons of sewage sludge is landfilled per annum [7]. One of the advantages of generating biogas for electricity generation from a sewage sludge is lowering pathogens in the landfills.

Figure 3. Classification of total waste generated in South Africa in 2011 [6].

2.3. Opportunities and Barriers in Waste to Energy The major drive for the deployment of more commercial scale biogas plant in South Africa will be governed by policies which restrict industries from disposing certain material such as organic waste in landfills. The municipalities require innovative strategies to do much more value addition to the different waste streams available at their disposal with biogas production being one of them.

2.3.1. Existing Biogas Projects or Plants in South Africa The current state of biogas production in South Africa is primarily small to medium scale, which is undertaken by private sectors. So far, only about 15 biogas plants produce



9

energy for electricity, heat or gas for on-site purpose or for a nearby private buyer. To date, technologies that have been implemented in landfill are in Johannesburg, Western Cape and KwaZulu-Natal Provinces. The purpose of these technologies is to capture methane already produced in landfills and combust it for the generation of electricity. Examples are the Bisadar (Durban, 6.5 MW), initiated in 2010 and Mariahill (Durban, 1MW, (20032010)) landfill sites in KZN. Companies such as the South African breweries, Petro SA (Biotherm, 4.2 MW, 2008) and Cere fruit farms (UASB digester, Veolia, 1998) have biogas plants in operation today.

2.3.2. Barriers to Waste to Energy Industry South Africa is still in infancy stage when it comes to deployment of biomass/waste to energy plants due to the lack of economic and technical viability. In addition, as mentioned above, South African waste management, at all levels from the industry, municipality and high corporation, is predominated by landfilling. Due to low gate fees in landfills, landfilling is highly favored because it is cheaper (Table 1). Table 2 shows clear details on specific hindrances addressed by stakeholders. Other, restriction includes the following: 1. Even though the cost of electricity is rapidly increasing, it remains low in terms of cost compared to waste to electricity which is expensive. 2. A lack of feed-in tariffs for renewable energy outside of the REIPPPP (Renewable Energy Independent Power Producer Procurement Program), which only applies to projects larger than 5 MW. 3. Absence of a policy/regulatory framework for grid connection by 15 Biogas to electricity, landfill gas to electricity, small-scale pyrolysis plants generating biodiesel, biodiesel from waste oils, and fuel replacement in industrial boilers using biomass. Table 1. Landfill gate fees in the large metropolitan municipalities [1]


10

Sarah G. Mungodla, Linda Z. Linganiso, Ella C. Linganiso et al. Table 2. Inhibitors and enablers of the South African biogas industry [2]

Inhibiting factors Lack of awareness, public, private and government Low electricity prices (make biogas more unviable) Tight margins, unable to pay qualified plant operators; lack of training and education around biogas

Current enablers SABIA, stakeholders and industry reflection in media Increasing Eskom tariffs

The cost and time taken to fulfil the current environmental licensing requirements (full EIA required for all plants that produce methane) Legislative requirements are quite divided and unclear No market for surplus energy generation 40 >30

Al2O3 % 30 99.5) for oil/water separation was recorded. This was attributed to very large surface-area-to-volume ratio (~600 m2/g giving rise to small pore size of 20 nm in the barrier layer) and high surface negative charge (0.70 mmol carboxylate groups/g oxidized chitin prepared via TEMPO/NaBr/NaCiO oxidizing method). The raw chitin from seafood waste with unique properties such as high crystallinity, high thermal stability, and high functional modification as well as abundant availability makes it a suitable candidate to replace the synthetic-based membranes. Recently, Liu et al. [54] investigated the separation of Pb2+ from Cu2+ and Pb2+ mixture using chitin whiskers coated on the potassium tetratitanate whiskers. The results indicated that, the material can be applied in polluted water streams to control or purify Pb 2+ ions from industry wastewater.


Transforming Fishery Waste into Chitin and Chitin Based Materials

237

6.3. Packaging Biopolymers have gained a lot of interest due to their attractive properties, such as biodegradability, recyclability and availability. Recent studies combine the high strength of chitin whiskers with bio-based polymers using different processing methods for packaging applications. Such materials would be valuable in reducing plastic waste or being used as alternative for packaging, especially for short service life, as plastics are quite of significant importance [55, 56]. Herrera et al. [55] developed functionalized blown films of plasticized polylactic acid/chitin nanocomposite for packaging applications by melt extrusion followed by film blowing technique (Figure 6). They found that the addition of chitin whiskers acts as antistatic and antifungal additive; and does not influence the barrier and optical properties of the resulting films (Figure 6). These results demonstrated that nanocomposite films can be used in carrier bags.

Figure 6. (A) The extrusion process to prepare master batch composite;(B) film blowing process of (a) reference compound, (b and c) the nanocomposite and (d) the nanocomposite final bags; (C) photographs of the reference and nanocomposite bags showing the antistatic effect (D) Antifungal activity of the reference and nanocomposite films (Reprinted with permission from Herrera et al. [55] Copyright 2016).


238

Teboho C. Mokhen and Mokgaotsa J. Mochane

6.4. Biomedical Applications There are several aspects that have to be considered for application of a material in tissue engineering such as high porosity with appropriate pore size, non-toxic to cells, biocompatible, interact with the cells to promote cell adhesion, proliferation, migration and differentiated cell function. Corvaglia et al. [57] developed composite films by reinforcing carrageen with chitin whiskers to evaluate their cell adhesion properties. Hela cells were used to evaluate the biocompatibility of the composite films and the cells interacted with the substrates and showed good proliferation. Although the films demonstrated poor adhesion, this membrane can be applied in biological fields. Chitin has poor mechanical properties which limit its application bone substitute and/or reconstruction; hence different fillers are often added into chitin and/or chitin-based materials to improve their mechanical properties [58, 59]. These fillers include hydroxyapatite (HAp), bioactive glass ceramic (BGC) and nanosilica, which are often added to produce hybrid material with appropriate mechanical properties [59-62]. BGC serves as an alternative to HAp due to their bioactivity, osteoinductivity and biodegradability. BGC were discovered by Larry Hench. They have the ability to bind to soft and hard tissues [63]. They have been used in bone repair due to the formation of carbonated apatite layer on their surface in physiological conditions. BGC are often prepared via sol-gel technique to afford high purity, surface area and homogeneity. Preparation of α-chitin/nanobioactive glass ceramic composite scaffold using lyophilisation method was reported by Peter et al. [61] to justify the abovementioned facts. The results showed a macroporous structure with pore size ranging from 150 to 500 μm, which was ideal as compared to prerequisite pore size for tissue engineering (150-200 μm). Degradation and swelling behavior were appropriate to allow the cell adhesion and growth. Cytocompatibility of the scaffold composite was evaluated using MTT assay, direct contact test and cell attachment studies. The results suggested that the developed composite scaffold can be used for tissue-engineering applications since there were no signs of toxicity and the cells were found to be adhered to the pore walls provided by scaffolds. On the other hand, Madfhumathi et al. [62] prepared chitin/nanosilica composite scaffolds for bone tissue engineering applications through lyophilisation process. Swelling behavior of the composite scaffolds was adequate for biomineralization in the cell culture medium. The cell viability was assessed using MTT assay; and the composite scaffolds were biocompatible, which suggest their application in bone repair. Recently, Pangon et al. [60] developed hydroxyapatite-hybridized chitosan/chitin whiskers bionanocomposite fibers for bone tissue engineering using electrospinning technique. The membranes were prepared by blending chitosan, chitin whiskers and polyvinyl alcohol (PVA) using succinic acid as spinning solvent at different ratios and electrospun into nanofibrous mats. In order to avoid the dissolution in water, the membranes were cross-linked using glutaraldehyde



239

vapors and then immersed in the hydroxyapatite to prepare hybrid composite scaffold. Cell viability and proliferation were evaluated using MTT assay. Cell attachment studies revealed that the cells were able to penetrate, attach and grow in the nanofibrous scaffolds. The mineralization was adequate and the results suggested that the scaffolds can be applied in bone repair. In order to improve the antibacterial activity of the scaffolds, silver nanoparticles are often added to the system. Silver nanoparticles are well-known for their attractive antimicrobial, antiviral and fungicidal activities. They received a considerable interest as new antibacterial agents, capable of eradicating the most antibacterial resistant microorganism and hence they have been applied in different fields such as biomedical and food packaging. Antibacterial and bioactive α- and β-chitin /nanobioactive glass ceramic/nanosilver composite scaffolds using lyophilisation process were developed by Srinivasan et al. [59]. The developed composite displayed adequate swelling and degradation properties. Antibacterial activity was conducted using a disc diffusion method, while cytocompatibility were assessed by Alamar Blue assay. The composite showed antibacterial efficacy towards E. coli and S. Aureus; and provided good cell adhesion and proliferation. Biomineralization studies showed high mineral deposits on the scaffold, which increased with incubation period without osteogenic supplements. These results demonstrated that the composite scaffolds can be employed in regenerating periodontal defects. Recently, Wang et al. [64] developed novel chitosan-based injectable hydrogels, enhanced by chitin nano-whiskers. The results showed that the mechanical properties of the chitosan/β-glycerophosphate disodium salt (CS/GP) injectable hydrogel were improved. Cytotoxity in vitro via MTT assay showed that the nanocomposite has a good compatibility. Since one of the aspect for tissue engineering involves structural integrity to prevent the pores of the scaffold from collapsing during neo-tissue with appropriate mechanical properties, Li et al. [65] prepared poly(L-lactide)/lactide-grafted whiskers composite scaffold by blending poly(L-lactide) and lactide grafted chitin whiskers. The composite scaffold in the presence of grafted chitin whiskers showed excellent mechanical properties, better biocompatibility, good cell adhesion and differentiation towards mouse embryo osteoblast precursor (MC3T3-E1). In terms of morphology, electrospun nanofibers have similar structure to the extracellular matrix (ECM) and therefore electrospun nanofibers can be used as supporting scaffold material for cell culture and tissue engineering. Electrospinning process affords the production of nanofibers with diameter ranging from several nanometers to few micrometres with unique properties such as high porosity, tuneable pore size and good mechanical properties. Liu et al. [45] reported an electrospun composite nanofiber membrane of poly(Llactide) and grafted chitin whiskers for bone tissue repair. Cytotoxicity and cell attachment studies were evaluated using mouse embryo osteoblast precursor (MC3T3-E1) by the αMEM assay. The cells were able to attach and spread in the nanofibrous scaffolds. These


240


results demonstrated that the nanofibrous scaffolds support the cell adhesion and proliferation which open doors for their application in different tissue engineering applications.

6.5. Wound Dressing Chitin has been demonstrated as one of the attractive material for wound dressing due to its unique biological properties. Hydrogels [66], electrospun nanofibers [9], and nonwoven fabrics [67], were produced using chitin for wound dressing. Recently, the utilization of electrospun nanofibers received considerable interest due to their size (20-500 nm) and architectural structure, similar to the collagen structure of native extracellular matrix (ECM). The size of collagen multifibrils in ECM is also of a nanofiber scale, ranging from 50 to 500 nm. Noh et al. [9] developed chitin nanofibers to be used as a wound dressing through electrospinning. In vitro, biological assays revealed a positive influence on the adhesion, growth and proliferation of human keratinocytes and fibroblasts and demonstrated the potential of chitin nanofibers to promote cellular response of cells. These demonstrated that the electrospun nanofibers with large surface-to-area ratio can be employed in wound healing and in regeneration of oral mucosa and skin. Naseri et al. [41] exploited the high strength of chitin whiskers by reinforcing electrospun chitosan/polyethylene oxide-based fibers reinforced for wound dressing. Composite scaffold structural integrity was improved also by crosslinking using genipin solution. Cytocompatibility of the chitin whiskers was evaluated using adipose derived (ASCs) stem cells and L929 cell lines. It was found that the chitin whiskers were non-toxic on both cells and the cells were growing normally and exhibited normal morphology. In the case of the cross-linked composite scaffolds, the water vapor permeation rate (WVTR) of 4134 g m2 day-1, and BET surface area of 35 m2g-1 were recorded. Cytocompatibility results for the composite scaffolds demonstrated non-toxicity effect on the cell growth, suggesting that the composite materials can be used for wound dressing. Some studies included the silver nanoparticles to improve the bactericidal of the tissue scaffolds to avoid complications of secondary infections, which may delay the healing process [68, 69]. The application of these scaffolds demonstrated suitable wound dressing with antibacterial activity towards E. Coli and S. aureus and good blood-clotting ability as well as good cell attachment.

6.6. Neuron Repair The biocompatibility and non-toxicity of chitin can be exploited by mixing with other constituents to improve its properties to afford its application in neuron repairing [69, 70]. Recent studies demonstrated that the addition of carbon nanotubes into chitin enhanced the electric conductivity of the composite materials [70, 71]. Singh et al. [67] fabricated



241

chitin/carbon nanotubes composite films for neuron repair using 1-ethyl-3methylimidazolium (EMI Ac) ionic liquid to improve the chitin solubility and carbon nanotubes dispersion. Chitin was added into multi walled carbon nanotube (MWNTs), coated with carboxymethyl cellulose and casted to obtain thin composite films. The results demonstrated that the biocompatible, electrical conductive chitin/MWNT composite provided adhesion and proliferation of Human mesenchymal stem cells.

6.7. Other Applications Proton exchange membrane (PEM) fuels has gained lot of interest as a novel powersource for small electronics devices because of valuable properties such high energy efficiency, easy fuel storage, low operating temperature, and simplicity on device design [72]. Chitin has high strength and adsorption properties and therefore it can provide the PEM with better mechanical properties as well as higher proton conductivity from its affinity to water and high water-holding capacity which contribute to the proton transfer. The interwhisker three-dimensional networks can facilitate the proton conductivity of the composite material by providing continuous hopping pathway for protons transportation through the membrane. The promising results were demonstrated by Zhang et al. [68]. They found that the increase in the whiskers content led to more interwhisker networks, which improved the proton conductivity of the composite material. Despite its low proton conductivity, chitosan has been explored as an alternative PEM due to its easy availability, low fuel crossover, and good film-forming ability [73-75].

CONCLUSION Chitin received less interest due to its limited solubility with most of research studies based on its derivatives. This opens doors for researchers to explore innovative ideas to improve the solubility which can further afford other applications. Chitin from seafoods’ residues has a wide range of applications to solve problems related to the current environmental crisis. It can be used in packaging, biomedical applications and wastewater treatment, which are most important aspects of healthy human life. Its advantages include easy availability and low costs, to mention a few. It can be argued that, the possibility to functionalized and/or produce different derivatives from chitin makes the most valuable primary source for a wide spectrum of applications. Chitin and chitin-based materials with unique properties clearly reveal that these materials are exciting and hold a great deal for future applications.


242


REFERENCES [1]

Riccardo, A. A. Muzzarelli, Joseph Boudrant, Diederick Meyer, Nicola Manno, Marta DeMarchis, and Maurizio G. Paoletti. 2012. “Current views on fungal chitin/chitosan, human chitinases, food preservation, glucans, pectins and inulin: A tribute to Henri Braconnot, precursor of the carbohydrate polymers science, on the chitin bicentennial.” Carbohydrate Polymers, 87:995-1012. https://doi.org/10.1016/ j.carbpol.2011.09.063. [2] Prameela Kandra, Murali M. Challa, and Hemalatha K. P. Jyothi. 2012. “Efficient use of shrimp waste: present and future trends.” Applied Microbiology and Biotechnology 93:17-29.doi:10.1007/s00253-011-3651-2. [3] Majeti N. V. Kumar. 2000. “A review of chitin and chitosan applications.” Reactive and Functional Polymers 46:1-27. https://doi.org/10.1016/S1381-5148(00)00038-9. [4] M. Dash, F. Chiellini, R. M. Ottenbrite, and E. Chiellini. 2011. “Chitosan-A versatile semi-synthetic polymer in biomedical applications.” Progress in Polymer Science 2011. 36: 981-1014. https://doi.org/10.1016/j.progpolymsci.2011.02.001. [5] http://www.gov.za/sites/www.gov.za/files/37714_2-6_Act26of2014NatEnviron ManWaste_aa.pdf. [6] Olfa Ghorbel-Bellaaj, Islem Younes, Hana Maâlej, Sawssen Hajji, and Moncef Nasri. 2012. “Chitin extraction from shrimp shell waste using Bacillus bacteria.” International Journal of Biological Macromolecules 5:1196-1201. https://doi.org/ 10.1016/j.ijbiomac.2012.08.034. [7] Ning Yan and Xi Chen. 2015. “Don't waste seafood waste: Turning cast-off shells into nitrogen-rich chemicals would benefit economies and the environment.” Nature 524: 155-158. doi:10.1038/524155a. [8] https://www.chemistryworld.com/podcast/chitin/6478. Article last visited on the 31/03/2017. [9] Hyung K. Noh, Sung W. Lee, Jin-Man Kim, Ju-Eun Oh, Kyung-Hwa Kim, ChongPyoung Chung, Soon-Chul Choi, Won H. Park, and Byung-Moo Min.2006. “Electrospinning of chitin nanofibers: degradation behavior and cellular response to normal human keratinocytes and fibroblasts.” Biomaterials 2006. 27:3934-3944. https://doi.org/10.1016/j.biomaterials.2006.03.016. [10] Surinder Kaur, and Gurpreet S. Dhillon. 2015. “Recent trends in biological extraction of chitin from marine shell wastes: a review.” Critical Reviews in Biotechnology 35: 44-61. http://dx.doi.org/10.3109/07388551.2013.798256. [11] Islem Younes and Marguerite Rinaudo. 2015. “Chitin and chitosan preparation from marine sources. Structure, properties and applications.” Marine Drugs 13:11331174. doi:10.3390/md13031133.



243

[12] Hongyang Ma, Christian Burger, Benjamin S. Hsiao, and Benjamin Chu. 2011. “Ultrafine polysaccharide nanofibrous membranes for water purification.” Biomacromolecules 12:970-976. doi: 10.1021/bm1013316. [13] Yimin Fan, Tsuguyuki Saito, and Akira Isogai. 2007. “Chitin nanocrystals prepared by TEMPO-mediated oxidation of α-chitin.” Biomacromolecules 9:192-198. doi: 10.1021/bm700966g. [14] Hong-Ping Zhao, Xi-Qiao Feng, and Huajian Gao. 2007. “Ultrasonic technique for extracting nanofibers from nature materials.” Applied Physics Letters 90:073112. doi: 10.1063/1.2450666. [15] Shinsuke Ifuku, Masaya Nogi, Kentaro Abe, Masafumi Yoshioka, Minoru Morimoto, Hiroyuki Saimoto, and Hiroyuki Yano.2011. “Simple preparation method of chitin nanofibers with a uniform width of 10-20 nm from prawn shell under neutral conditions.” Carbohydrate Polymers 84:762-764. https://doi.org/10.1016/ j.carbpol.2010.04.039. [16] Shinsuke Ifuku, Masaya Nogi, Masafumi Yoshioka, Minoru Morimoto, Hiroyuki Yano, and Huroyuki Saimoto.2010. “Fibrillation of dried chitin into 10-20nm nanofibers by a simple grinding method under acidic conditions.” Carbohydrate Polymers 81: 134-139. https://doi.org/10.1016/j.carbpol.2010.02.006. [17] Byung-Moo Min, Sung W. Lee, Jung N. Lim, Young You, Taek S. Lee, Pil H. Kang, Won H. Park. 2004. “Chitin and chitosan nanofibers: electrospinning of chitin and deacetylation of chitin nanofibers.” Polymer 45:7137-7142. https://doi.org/10.1016/ j.polymer.2004.08.048. [18] Gopalan K. Nair, and Alain Dufresne. 2003. “Crab shell chitin whisker reinforced natural rubber nanocomposites. 1. Processing and swelling behavior.” Biomacromolecules, 4:657-665. doi: 10.1021/bm020127b. [19] Olga I. Bogdanova, Dmitry K. Polyakov, Dmitry R. Streltsov, Alevtina I. Kulebyakina, Anton S. Orekhov, Alexandra L. Vasiliev, and John Blackwell. 2017. “Fabrication and mechanical properties of composite based on β-chitin and polyacrylic acid.” Carbohydrate Polymers 157:1496-1502. https://doi.org/10.1016/ j.carbpol.2016.11.032. [20] Asier M. Salaberria, Rene H. Diaz, Jalel Labidi, and Susana C. M. Fernandes. 2015. Preparing valuable renewable nanocomposite films based exclusively on oceanic biomass-Chitin nanofillers and chitosan. Reactive and Functional Polymers 89:3139. https://doi.org/10.1016/j.reactfunctpolym.2015.03.003. [21] Jacob D. Goodrich, and William T. Winter. 2007. “α-Chitin nanocrystals prepared from shrimp shells and their specific surface area measurement.” Biomacromolecules 8: 252-257. doi: 10.1021/bm0603589. [22] Arnaud Morin, and Alain Dufresne. 2002. Nanocomposites of chitin whiskers from Riftia tubes and poly (caprolactone). Macromolecules 35:2190-2199. doi: 10.1021/ma011493a.


244


[23] F. S. Kittur, K. V. Prashanth, K. Udaya Sankar, and R. N. Tharanathan. 2002. “Characterization of chitin, chitosan and their carboxymethyl derivatives by differential scanning calorimetry.” Carbohydrate Polymers 49:185-193. https://doi.org/10.1016/S0144-8617(01)00320-4. [24] Chong Li, Junxia Hou, Jianjung Gu, Qiuyan Han, Ying Guan, and Yongju Zhang. 2015. “Synthesis and thermal gelation of hydroxypropyl chitin.” RSC Advances, 5: 39677-39685. doi: 10.1039/C5RA03967C. [25] Seong S. Kim, Seon J. Kim, Yoon D. Moon, and Young M. Lee. 1994. “Thermal characteristics of chitin and hydroxypropyl chitin.” Polymer 35:3212-3216. https://doi.org/10.1016/0032-3861(94)90124-4. [26] In K. Park, and Young H. Park. 2001. “Preparation and structural characterization of water‐soluble O‐hydroxypropyl chitin derivatives.” Journal of Applied Polymer Science 80:2624-2632. doi: 10.1002/app.1374. [27] Riccardo A. A. Muzzarelli, Mario Guerrieri, Gaia Goteri, Corrado Muzzarelli, Tatiana Armeni, Rorberto Ghiselli and Maria Cornelissen. 2005. “The biocompatibility of dibutyryl chitin in the context of wound dressings.” Biomaterials 26:5844-5854. https://doi.org/10.1016/j.biomaterials.2005.03.006. [28] C. Muzzarelli, O. Francescangeli, G. Tosi, and R. A. A. Muzarelli. 2004. “Susceptibility of dibutyryl chitin and regenerated chitin fibres to deacylation and depolymerization by lipases.” Carbohydrate Polymers 56:137-146. https://doi.org/ 10.1016/j.carbpol.2004.01.002. [29] S. I. Jang, J. Y. Mok, I. H. Jeon, K. H. Park, T. T. Nguyen, J. S. Park, H. M. Hwang, M. S. Song, D. Lee, and K. Y. Chai. 2012. “Effect of electrospun non-woven mats of dibutyryl chitin/poly (lactic acid) blends on wound healing in hairless mice.” Molecules 17:2992-3007. doi: 10.3390/molecules17032992. [30] Akira Makino, Masashi Ohmae, and Shiro Kobayashi. 2006. “Synthesis of fluorinated chitin derivatives via enzymatic polymerization.” Macromolecular Bioscience 6:862-872. doi: 10.1002/mabi.200600128. [31] Kok S. Chow, and Eugene Khor. 2002. “New flourinated chitin derivatives: synthesis, characterization and cytotoxicity assessment.” Carbohydrate Polymers 47:357-363. https://doi.org/10.1016/S0144-8617(01)00190-4. [32] Seiichi Tokura, Koki Itoyama, Norio Nishi, Shin-Ichiro Nishimura, Ikuo Saiki and Ichiro A. Nishimura. 1994. “Selective sulfation of chitin derivatives for biomedical functions.” Journal of Macromolecular Science, Part A, 31:1701-1718. http://dx.doi.org/10.1080/10601329408545878. [33] Akira Makino, Hideaki Nagashima, Masashi Ohmae, Nad Shiro Kobayashi. 2007. “Chitinase-catalyzed synthesis of an alternatingly N-sulfonated chitin derivative.” Biomacromolecules 8:188-195. doi: 10.1021/bm0609240.



245

[34] R. Jayakumar, N. New, S. Tokura, and H. Tamura R. 2007. “Sulfated chitin and chitosan as novel biomaterials.” International Journal of Bbiological Macromolecules 40:175-181. https://doi.org/10.1016/j.ijbiomac.2006.06.021. [35] Marguerire Rinaudo. 2006. “Chitin and chitosan: properties and applications.” Progress in Polymer Science, 31:603-632. https://doi.org/10.1016/j.progpolymsci. 2006.06.001. [36] Wan C. A. Andrew, Eugene Khor, and Garth W. Hastings. 1998. “The influence of anionic chitin derivatives on calcium phosphate crystallization.” Biomaterials 19:1309-1316. https://doi.org/10.1016/S0142-9612(98)00046-5. [37] Keisuke Kurita, Masao Inoue, and Manabu Harata. 2002. “Graft copolymerization of methyl methacrylate onto mercaptochitin and some properties of the resulting hybrid materials.” Biomacromolecules 3:147-152. doi: 10.1021/bm0101320. [38] Chiyo Yamamoto, Tomoko Hayashi, and Yoshio Okamoto. 2003. “Highperformance liquid chromatographic enantioseparation using chitin carbamate derivatives as chiral stationary phases.” Journal of Chromatography A 1021:83-91. https://doi.org/10.1016/j.chroma.2003.09.017. [39] Sol A. Rodriguez, Erin Weese, Javier Nakamatsu and Fernado Torres. 2016. “Development of Biopolymer Nanocomposites Based on Polysaccharides Obtained from Red Algae Chondracanthus chamissoi Reinforced with Chitin Whiskers and Montmorillonite.” Polymer-Plastics Technology and Engineering, 55:1557-1564. http://dx.doi.org/10.1080/03602559.2016.1163583. [40] Yan Qin, Shuangling Zhang, Jing Yu, Jie Yang, Lui Xiong, and Qingjie Sun. 2016. “Effects of chitin nano-whiskers on the antibacterial and physicochemical properties of maize starch films.” Carbohydrate Polymers, 147: 372-378. http://dx.doi.org/ 10.1016/j.carbpol.2016.03.095. [41] Narges Naseri, Constance Algan, Valencia Jacobs, Maya John, Kristiina Oksman, Aji P. Mathew. “Electrospun chitosan-based nanocomposite mats reinforced with chitin nanocrystals for wound dressing.” Carbohydrate Polymers, 2014. 109:7-15. https://doi.org/10.1016/j.carbpol.2014.03.031. [42] Jittrawadee Sriupayo, Pitt Supaphol, John Blackwell, and Ratana Rujiravanit. 2005. “Preparation and characterization of α-chitin whisker-reinforced chitosan nanocomposite films with or without heat treatment.” Carbohydrate Polymers, 62:130-136. https://doi.org/10.1016/j.carbpol.2005.07.013. [43] Panya Wongpanit, Neeracha Sanchavanakit, Prasit Pavasant, Tanom Bunaprasert, Yasuhiko Tabata, Ratana Rujiravanit. 2007. “Preparation and characterization of chitin whisker-reinforced silk fibroin nanocomposite sponges.” European Polymer Journal 43:4123-4135. https://doi.org/10.1016/j.eurpolymj.2007.07.004. [44] Nadia. A. Mohamed, Hend E. Salam, Magdy W. Sabaa, and Gamaal R. Saad. 2016. “Synthesis and characterization of biodegradable copoly (ether-ester-urethane)s and


246

[45]

[46]

[47]

[48]

[49]

[50]

[51]

[52]

[53]

[54]

Teboho C. Mokhen and Mokgaotsa J. Mochane their chitin whisker nanocomposites.” Journal of Thermal Analysis and Calorimetry, 125:163-173. doi: 10.1007/s10973-016-5388-8. Hua Liu, Wenjun Lui, Binghong Luo, Wei Wen, Mingxian Liu, Xiaoying Wang and Changren Zhou. 2016. “Electrospun composite nanofiber membrane of poly (llactide) and surface grafted chitin whiskers: Fabrication, mechanical properties and cytocompatibility.” Carbohydrate Polymers, 147: 216-225. https://doi.org/10.1016/ j.carbpol.2016.03.096. Gopalan K. Nair, and Alain Dufresne. 2003. “Crab shell chitin whisker reinforced natural rubber nanocomposites. 2. Mechanical behavior.” Biomacromolecules, 4:666-674. doi: 10.1021/bm0201284. Gopalan K. Nair, Alian Dufresne, Alessadro Gandini and Mohamed N. Belgacem. 2003. “Crab shell chitin whiskers reinforced natural rubber nanocomposites. 3. Effect of chemical modification of chitin whiskers.” Biomacromolecules, 4:1835-1842. doi: 10.1021/bm030058g. Thi T. Nge, Naruhito Hori, Akio Takemura, Hirokuni Ono, and Tsunehisa Kimura. 2003. “Phase behavior of liquid crystalline chitin/acrylic acid liquid mixture.” Langmuir, 19:1390-1395. doi: 10.1021/la020764n. Thi T. Nge, Naruhito Hori, Akio Takemura, Hirokuni Ono, and Tsunehisa Kimura. 2003. “Synthesis and orientation study of a magnetically aligned liquid‐crystalline chitin/poly (acrylic acid) composite.” Journal of Polymer Science Part B: Polymer Physics, 41:711-714. doi: 10.1002/polb.10428. Thi T. Nge, Naruhito Hori, Akio Takemura, Hirokuni Ono, and Tsunehisa Kimura. 2003. “Synthesis and FTIR spectroscopic studies on shear induced oriented liquid crystalline chitin/poly (acrylic acid) composite.” Journal of Applied Polymer Science 90:1932-1940. doi: 10.1002/app.12870. Jirawut Junkasem, Ratana Rujiravanit, Brian P. Grady, and Pitt Supaphol. 2010. “X‐ ray diffraction and dynamic mechanical analyses of α‐chitin whisker‐reinforced poly (vinyl alcohol) nanocomposite nanofibers.” Polymer International, 59:85-91. doi: 10.1002/pi.2693. Jittrawadee Sriupayo, Pitt Supaphol, John Blackwell, and Ratana Rujiravanit. 2005. “Preparation and characterization of α-chitin whisker-reinforced poly (vinyl alcohol) nanocomposite films with or without heat treatment.” Polymer 46:5637-5644. https://doi.org/10.1016/j.polymer.2005.04.069. Jirawit Junkasem, Ratana Rujiravanit, and Pitt Supaphol. 2006. “Fabrication of αchitin whisker-reinforced poly (vinyl alcohol) nanocomposite nanofibres by electrospinning.” Nanotechnology, 17:4519. doi:10.1088/0957-4484/17/17/039. Juan Liu, Qin-guo. Li, and Wen-jing Xue. 2017. “Separation of lead with a novel ion separating agent prepared by clothing a chitin whisker on a potassium tetratitanate whisker.” Materials, 10:262. doi:10.3390/ma10030262.



247

[55] Natalia Herrera, Hendrik Roch, Asier M. Salaberria, Maximiliano A. Pino-Orellana, Jalel Labidi, Susana C. M. Fernandes, Deodato Radic, Angel Leiva and Kristiina Oksman. 2016. “Functionalized blown films of plasticized polylactic acid/chitin nanocomposite: Preparation and characterization.” Materials & Design, 92:846-852. https://doi.org/10.1016/j.matdes.2015.12.083. [56] Natalia Herrera, Asier M. Salaberria, Aji P. Mathew, and Kristiina Oksman. 2016. “Plasticized polylactic acid nanocomposite films with cellulose and chitin nanocrystals prepared using extrusion and compression molding with two cooling rates: effects on mechanical, thermal and optical properties.” Composites Part A: Applied Science and Manufacturing 83:89-97. https://doi.org/10.1016/j. compositesa.2015.05.024. [57] Stefani Corvaglia, Sol Rodriguez, Giuseppe Bardi, Fernando G. Torres and Daniel Lopez. 2016. “Chitin whiskers reinforced carrageenan films as low adhesion cell substrates.” International Journal of Polymeric Materials and Polymeric Biomaterials, 65:574-580. doi:10.1080/00914037.2016.1149846. [58] Ziping Zou, Chuang lou, Binghong Lou, Wei Wen, Mingxian Lui, and Changren Zhou. 2016. “Synergistic reinforcing and toughening of poly (l-lactide) composites with surface-modified MgO and chitin whiskers.” Composites Science and Technology 133:128-135. https://doi.org/10.1016/j.compscitech.2016.07.025. [59] Sowmya Srinivasan, Sudheesh Kumar, Sreeja V. Nair, and Jayakumar Rangasamy. 2013. “Antibacterial and bioactive α-and β-chitin hydrogel/nanobioactive glass ceramic/nano silver composite scaffolds for periodontal regeneration.” Journal of Biomedical Nanotechnology 9:1803-1816. doi: 10.1166/jbn.2013.1658. [60] Autchara Pangon, Somsak Saesoo, Nattika Saengkrit, Uracha Ruktanonchai, and Varol Intasanta. 2016. “Hydroxyapatite-hybridized chitosan/chitin whisker bionanocomposite fibers for bone tissue engineering applications.” Carbohydrate Polymers 144:419-427. https://doi.org/10.1016/j.carbpol.2016.02.053. [61] Mathew Peter, Pandian T. D. Kumar, Nelson S. Binulal, Shanti V. Nair, Hiroshi Tamura, and Rangasamy Jayakumar 2009. “Development of novel αchitin/nanobioactive glass ceramic composite scaffolds for tissue engineering applications.” Carbohydrate Polymers 78:926-931. https://doi.org/10.1016/ j.carbpol.2009.07.016. [62] K. Madhumathi, Sudheesh P. T. Kumar, K. C. Kavya, T. Furuike, H. Tumura, S. V. Nair, and R. Jayakumar. 2009. “Novel chitin/nanosilica composite scaffolds for bone tissue engineering applications.” International Journal of Biological Macromolecules 45:289-292. https://doi.org/10.1016/j.ijbiomac.2009.06.009. [63] R. Jayakumar, Deepthy Menon, K. Manzoor, S. V. Nair, and H. Tamura. 2010. “Biomedical applications of chitin and chitosan based nanomaterials-A short review.” Carbohydrate Polymers, 82:227-232. https://doi.org/10.1016/ j.carbpol.2010.04.074.


248


[64] Qianqian Wang, Siyu Chen, and Dajun Chen. 2017. “Preparation and characterization of chitosan based injectable hydrogels enhanced by chitin nanowhiskers.” Journal of the Mechanical Behavior of Biomedical Materials, 65:466477. https://doi.org/10.1016/j.jmbbm.2016.09.009. [65] Cairong Li, Hua Liu, Binghong Luo, Wei Wen, Liumin He, Mingxian Liu, Changren Zhou. 2016. “Nanocomposites of poly (l-lactide) and surface-modified chitin whiskers with improved mechanical properties and cytocompatibility.” European Polymer Journal, 81:266-283. https://doi.org/10.1016/j.eurpolymj. 2016.06.015. [66] H. Tamura, T. Furuike, S. V. Nair, R. Jayakumar. 2011. “Biomedical applications of chitin hydrogel membranes and scaffolds.” Carbohydrate Polymers, 84:820-824. https://doi.org/10.1016/j.carbpol.2010.06.001. [67] Y. Ohshima, K. Nishino, Y. Yonekura, S. Kishimoto, and S. Wakabayashi. 1987. “Clinical application of chitin non-woven fabric as wound dressing.” European Journal of Plastic Surgery 10:66-69. doi: 10.1007/BF00578375. [68] K. Madhumathi, Sudheesh P. T. Kumar, S. Abhilash, V. Sreeja, H. Tamura, K. Manzoor, S. V. Nair, and R. Jayakumar. 2010. “Development of novel chitin/nanosilver composite scaffolds for wound dressing applications.” Journal of Materials Science: Materials in Medicine 21:807-813. doi: 10.1007/s10856-0093877-z. [69] Sudheesh P. T. Kumar, S. Abhilash, K. Manzoor, S. V. Nair, H. Tamura, and R. Jayakumar.2010. “Preparation and characterization of novel β-chitin/nanosilver composite scaffolds for wound dressing applications.” Carbohydrate Polymers 80:761-767. https://doi.org/10.1016/j.carbpol.2009.12.024. [70] Nandita Singh, Jinhu Chen, Krzystof K. K. Koziol, Keith R. Hallam, Dawid Janas, Avinash J. Patil, Ally Strachan, Jonathan G. Hanley and Sameer S. Rahatekar. 2016. “Chitin and carbon nanotube composites as biocompatible scaffolds for neuron growth.” Nanoscale 8: 8288-8299. doi: 10.1039/C5NR06595J. [71] Nandita Singh, Krzystof K. K. Koziol, Jinhu Chen, Avinash J. Patil, Jeffrey W. Gilman, Paul C. Trulove, Wael Kafienah and Sameer S. Rahatekar.2013. “Ionic liquids-based processing of electrically conducting chitin nanocomposite scaffolds for stem cell growth.” Green Chemistry 15:1192-1202. doi: 10.1039/C3GC37087A. [72] Chan Zhang, Xupin Zhuang, Xiaojie Li, Wei Wang, Bowen Cheng, Weimin Kang, Zhanjun Cai, and Mengqin Li. 2016. “Chitin nanowhisker-supported sulfonated poly (ether sulfone) proton exchange for fuel cell applications.” Carbohydrate Polymers 140:195-201. https://doi.org/10.1016/j.carbpol.2015.12.029. [73] Bijay P. Tripathi, and Vinod K. Shahi. 2011. “Organic-inorganic nanocomposite polymer electrolyte membranes for fuel cell applications.” Progress in Polymer Science 367:945-979. https://doi.org/10.1016/j.progpolymsci.2010.12.005.



249

[74] B. Smitha, S. Sridhar, and A. Khan. 2005. “Chitosan-sodium alginate polyion complexes as fuel cell membranes.” European Polymer Journal 41:1859-1866. https://doi.org/10.1016/j.eurpolymj.2005.02.018. [75] Yahua Liu, Jingtao Wang, Haoqin Zhang, Chuanming Ma, Jindun Liu, Shaokui Cao, and Xiang Zhang. 2014. “Enhancement of proton conductivity of chitosan membrane enabled by sulfonated graphene oxide under both hydrated and anhydrous conditions.” Journal of Power Sources 269:898-911. https://doi.org/10.1016/ j.jpowsour.2014.07.075.





Chapter 12

BIOGAS PRODUCTION FROM MAIZE CROP AND MAIZE WASTES Linda Z. Linganiso*, Amanda Phungula, Tshwafo E. Motaung and Sandile P. Songca Department of Chemistry, University of Zululand, KwaDlangezwa, KwaZulu Natal, South Africa

ABSTRACT After harvesting, vast amount of agricultural biomass is burnt in the open field annually. The burning of biomass residues releases greenhouse gases which lead to climate change and global warming. In addition, there is a worldwide increase in the demand for energy crops for the purpose of biogas production. A maximum methane yield per hectare should be achieved with energy crops. In this chapter, a summary of researches involving maize waste together with maize crops utilization in the production of biogas is discussed. The climate, location, maize diversity, harvesting time, harvesting technology, conservation, chopping, additives, environmental conditions, fermentation technology, substrate composition and plant management are all factors that must be considered when both maize crops and maize residues are used for biogas production. Maize crops as well as maize waste have been used extensively in biogas production by many and this chapter will focus on both maize crop and maize waste utilization in methane fermentation process (biogas production).

Keywords: maize crop, maize waste, anaerobic digestion, biogas production

*

Corresponding Author address. Email: [email protected].


252

Linda Z. Linganiso, Amanda Phungula, Tshwafo E. Motaung et al.

1. INTRODUCTION 1.1. Agricultural Biomass and Renewable Energy During the 21st century, the world has been facing challenges due to growth population which leads to high demand of energy, which later cause an increase in energy consumption and decrease in supplies of fossil fuels. This has redirected the researchers’ focus towards the generation of green electricity from renewable energy sources as opposed to fossil fuel based. Progress towards the development of new technological procedures of energy production has been noted in recent years [1]. Amos and the co-workers [2] reported the necessity to increase sustainable energy supply systems intended to cover the energy demand from renewable sources. Renewable resources of energy are a part of the European battle against climate changes, while they add value to economic growth, creating jobs for unemployed people and offering energetic safety. Agricultural biomass is involved in biogas production and is very vital because it offers considerable environmental benefits [3] and is another source of income for farmers. Agricultural biomass also generates renewable energy such as biogas. Biogas from sewage digesters usually contains 55-65% methane, 35-45% carbon dioxide and less than 1% nitrogen, respectively. On the other hand, biogas from organic waste digesters contains 60-70% methane, 30-40% carbon dioxide and less than 1% nitrogen, correspondingly. While in landfill sites, the amount of methane produced is usually 45-55% but carbon dioxide and nitrogen were identified to be 30-40% and 5-15%, respectively [4]. Biogas composition is made up of hydrogen sulphide, other sulphur compounds, compounds such as siloxanes, aromatic and halogenated compounds. Even though the sum of trace compounds is lower compared to methane, they can have significant negative effects environmentally such as stratospheric ozone depletion, the greenhouse effect and/or reduction of the quality of local air [5].

1.2. Biogas Biogas is a combination of various gases produced when organic matter is broken down in the absence of oxygen. Biogas can be produced from raw materials such as manure, agricultural waste, municipal waste, sewage, plant material, food waste or green waste. Biogas is a renewable energy source. It can be produced by anaerobic digestion with anaerobic organisms which digest material in a closed system [6]. Biogas is mainly methane (CH4) and carbon dioxide (CO2) and can contain small quantities of hydrogen sulfide (H2S), siloxanes and moisture. The gases such as methane, carbon monoxide (CO) and hydrogen can be burned or oxidized with oxygen. The energy released allows biogas


Biogas Production from Maize Crop and Maize Wastes

253

to be used as a fuel, it can be used for any heating purposes such as cooking. It can also be used in a gas engine to change the energy from the gas to electricity and heat [7]. Biogas is manufactured as landfill gas (LFG), which is produced by the breakdown of biodegradable waste within a landfill site as a result of chemical reactions and microbes, or as digested gas, manufactured within an anaerobic digester. A biogas plant is the name usually given to an anaerobic digester that treats energy crops or farm wastes. It can be made by means of anaerobic digesters which are air-tight tanks with different configurations. These plants can be fed with energy crops or biodegradable wastes such as sewage sludge, food waste, maize silage and cattle manure, to mention a few. Throughout the process, the microorganisms convert biomass waste into biogas, primarily methane, carbon dioxide and digestate. Biogas is a renewable energy which can be used for heating, electricity, and in many other operations that use a reciprocating internal combustion engine such as GE Jenbacher or Caterpillar gas engines. Other internal combustion engines such as gas turbines are suitable for the conversion of biogas into both electricity and heat. The digestate is the remaining inorganic matter that was not transformed into biogas. It can be used as an agricultural fertiliser. In anaerobic digestion process, temperature is important for both microbial metabolic activities and the overall digestion rate, specifically, the rates of hydrolysis and methane formation. Anaerobic digestion process usually occurs within a wide range of temperatures. This temperature range has been broadly divided into two key processes: mesophilic and thermophilic digestion. Mesophillic digestion is the anaerobic digester that operates at the temperature range 35-38oC. On the other hand, the anaerobic digester that operates at the higher temperature range of 50o to 65oC is known as thermophilic digestion. In general, mesophilic anaerobic digestion of sewage sludge is more widely used compared to thermophilic digestion. However, as much as mesophilic digester is more stable in operation but a lower biogas production rate is obtained when in use. Also, it does not reduce the pathogen concentrations enough to produce Class A biosolids, a biosolid which contains no detectible levels of pathogens. Interest in the thermophilic digestion developed based on the facts that higher temperatures reduce pathogens and thermophilic temperatures provide more rapid reaction rates than mesophilic temperature. Thermophilic anaerobic digestion in general is more efficient in biogas production but associated with higher maintenance cost.

1.3. Maize and Maize Wastes in Biogas Production Appropriate substrates for agricultural biogas plants digestion are: animal manures, organic wastes and energy crops. Maize (Zea mays L.), clover grass (Trifolium), herbage (Poacae), fodder beet (Beta vulgaris), Sudan grass (Sorghum sudanense) and others are regarded as energy crops [8-10]. Maize is the mostly used crop in biogas production. It is


254


thought to have the top yield potential of field crops grown in Central Europe. The value of energy crops used in biogas production is established on the field [11]. Climate, location and maize diversity are vital in biogas generation from maize. Management of plant and the vegetation phase must be optimally chosen when maize is harvested. Figure 1 shows the influences on the biomass value using maize as an example for all phases of biogas production [12].

Figure 1. Biogas production from maize along the process of production [12].

1.4. Basic Biochemistry of Anaerobic Digestion When the organic material decomposes under anaerobic conditions, several products are produced including high energy biogas. During the synthesis of biogas, large and complex organic polymer chains are broken down into smaller molecules or gases such as hydrogen, methane and carbon dioxide. Different microorganisms are responsible for this process where each community requires a substrate produced by another type of anaerobic decomposing microbes. Therefore, both nutrients and microbial communities are required for an anaerobic digestion to occur and biogas to be generated. Anaerobic degradation takes place in four stages under different types of a microorganisms [13]. These include hydrolysis, acidogenesis, acetogenesis and methanogenesis, respectively. The four steps involved in methane fermentation process of biomass degradation is illustrated in Table 1.



255

Table 1. Steps involved in anaerobic oxidation of complex wastes

1.4.1. Hydrolysis Hydrolysis is the first phase of anaerobic degradation, where water reacts with large biopolymer chains. Biomass and biopolymers are then broken into simpler molecules such as acetate and hydrogen with microbial enzymes as catalyst [13]. Simpler molecules are easily absorbed into microbes cells and are used as nutrients and energy sources. Some microbes are dedicated into breaking down one type of a simpler molecule. For example, sugar monomers are broken down by enzyme called saccharolytic and proteolytic is an enzyme that degrade proteins. Moreover, the rate of hydrolysis highly depends on the nature of the substrate. Therefore, cellulose and hemicellulose degradation takes more time compared to proteins, hence the feedstock which contains higher amounts of cellulose and hemicellulose such as wood takes more time to hydrolyze than maize. In the enzymatic hydrolysis step, the water-insoluble organics can be solubilized by using water to break the chemical bonds and the resulted simple soluble compounds can be used by the bacterial cells. Hydrolysis is a relatively slow step and it can limit the rate of the overall anaerobic digestion process, especially when using solid waste as the substrate. Hydrolysis reaction is presented in Table 1. It is immediately followed by the acid-forming step acidogenesis. 1.4.2. Acidogenesis Acidogenesis is the second phase of anaerobic degradation process and is also called fermentation. Unlike hydrolysis, acidogenesis consists of numerous reactions steps (Table 1). The number of reactions that take place depends on the types of microorganisms and substrates in the digestion medium. More microorganisms are active in acidogenesis than in any other phase of anaerobic digestion, microbes are also involved in this step. Some of


256


these microbes includes, Bacteriodes, Eubacterium, Acetobacterium and Enterobacterium, to mention but a few. In this process, products from hydrolysis step are further broken down into organic acids such as acetic, propionic and lactic acid. Other molecules produced are alcohols, ammonia, carbon dioxide and hydrogen, respectively. Accumulation of acidic molecules including ammonia are not desirable for biogas production because they increase the acidity of the medium, which inactivates some microbes.

1.4.3. Acetogenesis During acetogenesis stage, products of the second stages are further broken down to smaller molecules under oxidative conditions. In this reaction step, protons are the final electron acceptors and hydrogen gas is produced. However, the amount of hydrogen gas formed must be decreased for the process to proceed because microorganism will have less energy for growth in high concentration of hydrogen. Therefore, hydrogen has to be constantly removed from the reaction medium. However, this step is inter-dependent with microorganism activities of the last phase of anaerobic digestion, methanogenesis which utilizes hydrogen to produce methane [13]. Additional products of the process are acetate, carbon dioxide and energy in the form of heat [13]. Some microorganisms that are involved in this step includes: Syntrophomonas, Syntrophus, Clostridium and Syntrobacter, to mention but a few. These organisms carry out various anaerobic oxidation reactions in syntrophic interrelation with acetogens, which are microorganisms that utilize hydrogen gas [14]. 1.4.4. Methanogenesis Methanogenesis is the last step of the anaerobic digestion process and is the crucial procedure which produces biogas (Table 1). In this step, both methane and carbon dioxide are produced by a number of methane generating microbial communities known as methanogens. The required substrates for these microorganisms are hydrogen gas, carbon dioxide and acetate, which are obtained from acetogenesis. Other available substrate such as methyl amines, various alcohols, and formates are also used for the generation of methane by certain types of methane producing microorganism. In the final reaction, methane is produced by methanogenic bacteria. These bacteria are capable of metabolizing formic acid, acetic acid, methanol, carbon monoxide, carbon dioxide and hydrogen to methane. Acetotrophic methanogens are usually the most dominant organisms that consume acetate and convert it into biogas. Acetate is responsible for about 70% of the biogas produced in a digestion tank. Methanogens are highly sensitive towards pH or toxic compounds such as heavy metals or organic pollutants. Therefore, it is important that optimal conditions are kept constant. A few basic parameters required for efficient operation of biomethanation system are discussed briefly in the following section.



257

1.5. Basic Parameter Requirements There are some basic requirements for efficient operation of biomethanation system. This section will highlight only five of the requirements for biomass degradation into methane.

1.5.1. Retention Time In general, high retention time value assists in permitting biological acclimation to toxic compounds. Not only this, it maximizes volatile mass removal capacity, increases required digester volume, as well as providing buffering capacity for protection against the effects of shock loadings and toxic compounds in waste waters and sludge of the reactor. 1.5.2. Process Temperature Most biogas producing bacteria are active in two temperature ranges (mesophilic range 30–35 ◦C and the thermophilic range 50 - 60oC). At temperatures between 40 and 50oC, biogas producing bacteria are inhibited. 1.5.3. pH Most anaerobic bacteria, including methane-producing bacteria perform well within a pH range of 6.8-7.2. The pH in the digestion tank primarily drops below 6.0 due to the production of volatile acids, but carbon dioxide is being released at the same time, so the pH rises above 7 to 8 and more, thereafter. As the reaction progresses, more volatile acids are absorbed by methane-forming bacteria as more carbon dioxide is released. In so doing, the acidity level decreases until the pH increases above 8. 1.5.4. Substrate Composition and Consistency of Feed Materials Biogas yield and composition are greatly affected by the composition of feed materials in respect of carbohydrate, fat and protein contents. Anaerobic digestion of carbohydrates yields 886 L biogas (with methane content of around 50%) per kg of VS destroyed. Similarly, anaerobic digestion of fats yields 1535 L biogas (with methane content of around 70%) per kg of VS and that of proteins yields 587 L biogas (with methane content of around 84%) per kg of VS destroyed. The water content in substrate should be about 90% of the weight of the total contents. If the water content in substrate is too low, acetic acid is to be accumulated, which inhibit the fermentation process and hence biogas production and also thick scum is to be formed on the surface. In case of fresh cattle dung, it has to be mixed with water on a unit volume basis (i.e., same volume of water for a given volume of dung) before feeding into the digester.


258


1.5.5. C/N Ratio A C/N ratio ranging from 20 to 30 is considered optimum for anaerobic digestion process. A C/N value of at least 25:1 is recommended for optimal gas production. If the C/N ratio is very high, methanogens will speedily consume the nitrogen for meeting their protein requirements and will no longer react with the left over carbon content of the material.

2. THE MARKET OVERVIEW OF AGRICULTURAL WASTES South African agricultural sector is experiencing various challenges such as climate change, overuse of synthetic fertilizers, environmental pollutions, drought and declining farming profitability. Poor agricultural practices such as intensive farming comes with numerous negative effects on the natural environment, human health and on a farmer’s ability to adjust to change. Most farmers are highly depended on synthetic fertilizers, pesticides and herbicides. This dependency reduces soil fertility, causes soil erosion, and pollutes water supplies, poisons fragile ecological systems and increases concentrations of greenhouse gases. In addition, farmers and workers are often exposed to toxic gases and acid rain. Acid rain has also killed thousands of people, globally. In 2009, 188 000 people died from acid rain. Furthermore, the capital needed for intensive agriculture is increasing. Also responsible for increasing input costs are increasing oil prices, raw materials price and fluctuations of the current exchange rates. These factors leave the farmers with less control over their businesses. In addition, intensified agriculture is usually accompanied with intensive mechanization, which results in lesser jobs on farms. Biogas technology business has a higher potential for the agricultural sector as few big farms in south Africa have a potential to build a commercial scale biogas plants. In this case, small scale farmers can sell their waste to large scale farmers for income. Larger farmers can be able sustain their biogas plants and combat increasing electricity by producing their own while providing small farmers with a more environmentally friendly organic fertilizer. In order to help the South African agricultural sector, principles of economics of scale should be introduced to SA farmers. Working together can be a solution to some of the challenges this industry is facing such as: lack of subsidies and growth support for conventional commercial agronomists and emerging black farmers, to mention but a few. Crops that produce large amounts of lost food and waste such as maize can provide abundant waste source to sustain commercial scale biogas plant for farmers. Moreover, such maize is one of the most planted crop in South Africa as it has been a large part of what South Africans consume.



259

3. MARKET STRUCTURE According to SA agriculture statistic 2008, approximately half of the maize produced in South Africa is used for animal feed and about 70% of this feed is directed to poultry. Also reported is that, human consumption of maize in South Africa has decreased due to the fact that, as population increases, the middle class increases also. Therefore, change of diet among South Africans has been noticed due to improvements in economic growth. Humans have shifted from maize to consuming more poultry products such as chicken and eggs. Annual national maize production in South Africa broadly varies according to rainfall. Average production has remained constant over time. This has been a major concern as consumption increased with the rising population. Therefore, both local and regional supply could be affected due to the fact that maize production does not meet the local demand. On the other hand, in the last 20 years, local poultry production has increased significantly. However, chicken is now one of the largest agricultural imports, due to the fact that South African poultry industry has not been able to meet the huge increase in local demand for white meat. These challenges are the cause of intensified farming of crops such as maize. Therefore, the market size for maize remains big in South Africa.

4. MARKET DRIVERS OF MAIZE TO ENERGY Energy crops are one of the best alternative to diversify agricultural production. It is also attractive to enhance the business of a farm. Farmers can utilize maize waste to generate electricity from biogas and improve the energy balance of a farm or sell excess electrify and organic fertilizer. Maize silage offers interesting yields, which is approximately 30 tons of total solids per hectare. According to various studies, maize grain produced from maize is not a suitable waste to produce biogas as maize silage, both from economic and nutritional points of view. According to Miroslav Hutňan [15], this was explained to be presumably due to a large portion of production costs which is used to obtain dry and pure grains [15]. Population growth, increasing urbanization and wealth accumulation could be the drivers for high need of biogas production from maize waste and other agriculture waste. South Africa’s population has been growing at almost 2% per year. In 2009, the country’s population was 49 million and is expected to increase to about 82 million by the year 2035. Therefore, food manufacturing or imports will have increased more to feed the growing population. In addition, the demand for certain food types will shift as more people become wealthier. Recently, South African citizens have illustrated an interesting change in food consumption. The middle class has increased by 30% between 2014 and 2016. Due to this change, a shift from stable grain crops to a more diverse diet has been observed. Particularly, the maize and bread consumption has


260


decreased and a massive increased consumption of chicken from 6kg to 27 kg per person has been observed [16]. Biogas presents an effective technology that could be driven by aforementioned factors. Maize waste can be converted to biogas, to generate green electricity to fuel the farmer’s machinery. The manufactured by-product fertilizer with more balance nutrients can be used to allow sustainable maize farming, where in cooperation, farmers can produce maize to meet the demand in poultry farming which could meet the increasing local demand for white meat and eggs.

5. BIOGAS INVESTMENT Regardless of the Independent Power Producer (IPP) tenders by South African government including biogas under its cogeneration procurement program, biogas investment was recently reduced by a price cap of less than ZAR1/kWh [17]. According to the reports, government emphasizes to place large-scale solar and wind power projects. Therefore, higher capital requirement to develop large scale biogas plant in South Africa is one of the challenge faced by this industry. Again, plants below 1MW are not able to connect and sell electricity to the national grid. According to the South African biogas association, large farmers have higher capabilities to produce larger amounts of electricity from biogas to fuel agricultural facilities from the crop waste. Therefore, maize is one of the most produced grain crop in South Africa and hence produces high volumes of waste. The most common practice the farmers will do after harvest to manage crop waste is to burn it in open field. This is not a good practice as it affects food production (crop) in all value chains due to drought. More revenue streams or investments are required to establish larger scale biogas plants.

6. IMPACT OF BIOGAS PLANT IN SOUTH AFRICAN AGRICULTURAL SECTOR One of the challenges in South Africa has been the establishment of policies which will ensure that agriculture contributes to the national economic policy objectives pronounced in the Reconstruction and Development Program (RDP), which is now summarized in the Growth, Employment and Redistribution (GEAR) strategy. The objectives of the strategy include economic growth; reducing income inequalities especially along racial lines; and eliminating poverty. The purpose of agricultural policy reforms is to ensure that agriculture contributes to these national objectives through the following: 

An increase in agricultural productivity and output, which will enhance the sector’s contribution to national economic growth.


Biogas Production from Maize Crop and Maize Wastes 

 

261

An increase in incomes for the poorest groups in society, through the creation of opportunities for small and medium-scale farmers to raise their production for own consumption and the market. The creation of additional employment opportunities in agriculture. An improvement in household food security through expanded production and a more equitable distribution of resources.

According to the national income statistics [18], it was suggested that the division presently accounts directly for 4 to 5% of the Gross Domestic Product (GDP). However, it is important to understand that agriculture contribution share is larger than the suggested quote of the GDP. The overall economic contribution of this industry is complex due to drought, which affects GDP by 0.5 to 2% or periods of extremely favorable rainfall. Also, agricultural sector plays a major role indirectly via its purchase of goods such as fertilizers and chemicals. On the other hand, it supplies raw materials to industry. About 66% of agricultural output is used as intermediate products in the sector. Based on these findings, agriculture has a higher potential to add value to the GDP via the establishments of biogas commercial plants, which will produce organic fertilizers for the farms and produce higher quality crops to further contribute to the GDP and becomes a pool for job creation in rural areas.

7. RECENT RESEARCH AND DEVELOPMENT (MAIZE CROP AND MAIZE WASTE) Many researchers have investigated the effect of sodium hydroxide pre-treatment on biogas production and biodegradability of corn stover (maize stalk) [19-21]. In all cases, sodium hydroxide proved to be efficient in improving biodegradability of corn stover and enhanced biogas production. Anaerobic mono and co-digestion of kitchen waste, corn stover, and chicken manure under mesophilic (37°C) conditions were conducted [22] in a batch mode to investigate the biomethane potential, biodegradability, methane production performance, and the stability of the process. Kitchen waste displayed the highest biodegradability of 94% compared to corn stover (45%) or chicken manure (47%). For kitchen waste, mono- and co-digestion with corn stover, chicken manure, or their mixture, the methane production performance was better at an S/I ratio of 1.5 than that of 3.0, whereas on the other side, corn stover, chicken manure, and their mixture, the S/I ratios of 1.5 and 3.0 showed suitability. A synergistic effect was found in the co-digestion process, which was mainly attributed to a proper carbon-to-nitrogen ratio and the reduced total volatile fatty acids-to-total alkalinity


262


ratio, thus providing better buffering capacity and supporting more microorganisms for efficient digestion [22]. Corn stover and other lignocellulosic biomass such as wheat straw, rice straw and leaves were pre-treated with chemical or thermochemical methods before being fed into the solid-state anaerobic digestion reactor [23]. The researchers involved [23] observed that solid-state anaerobic digestion reactor had major limitations. These included long retention time and the requirements of digested materials or leachate to inoculate the fresh feedstocks. They later found out that these challenges can be overcome with the improvements of the process and reactor design. In their conclusion, they stated that solidstate anaerobic digestion reactor continues to prove its capability to effectively convert waste material into energy. But, continued improvements of continuous and batch solidstate anaerobic digestion reactor processes is necessary to treat, not only municipal solid waste but lignocellulosic biomass such as crop residues and energy crops [23]. The application of rumen microorganisms to enhance anaerobic fermentation of corn stover (maize stalk) was investigated [24]. The results obtained showed that the conversion efficiency of corn stover reached 55–70%, when rumen microorganisms were used and rumen microorganisms appeared promising for the anaerobic fermentation of corn stover [24]. Zhengbo Yue et al., [25] performed similar work. Corn straw was pre-treated by rumen microorganisms in vitro and the experimental observations showed that rumen microorganisms pre-treatment was an effective and economic pretreatment method for maize straw [25]. The energetic of methane and bioethanol production potential were estimated using different agro-waste residues including maize waste [13]. The estimations were done using a baseline reference data of methane and bioethanol production yields and their properties. Corn stover produced remarkable high yield of both methane (biogas) and bioethanol as opposed to other renewable lignocellulosic feedstocks. The energy value of methane and bioethanol on unit ton basis is shown in Table 2. The analysis of the table revealed that the methane/bioethanol energy ratio for maize, wheat, rice and sugarcane based lignocellulosic biomass was to be about 1.15, 1.07, 0.95 and 0.83, respectively. This output energy ratio of methane/bio-ethanol increased for maize wastes as opposed to other agro-waste residues (Table 2). Table 2. Estimated energetic of methane and ethanol production potential Biomass Maize waste Wheat waste Rice straw Bagasse

Methane production Yield (kJ/ton) Energy (MJ) 208.80 10440.00 174.96 8748.00 167.04 8352.00 148.32 416.00

Ethanol production Yield (kg/ton) Energy (MJ) 338.12 9061.616 304.94 8172.392 328.64 8807.552 334.96 8976.928



263

Technical feasibility studies of methane-to-methanol production (Figure 2) from the landfill biogas system was undertaken and the results illustrated that this system is technically the most challenging one due to the fact that contaminants removal to parts per billion is required to produce methanol. This could only be done using CO2 WashTM technology [13].

Figure 2. Methane to methanol production process from the landfill biogas system.

Anaerobic co-digestion of chicken manure and corn stover in batch and Continuous Stirred Tank Reactor (CSTR) were investigated. The experimental results showed that at OLR of 4 g VS/L/d, stable and preferable methane yield of 223 ± 7 mL/g VS added were obtained which was equal to energy yield (EY) of 8.0 ± 0.3 MJ/kg VS added. In this study, pyrolysis was thought to be a promising technique to reduce biogas residues and to produce valuable gas products simultaneously [26]. The addition of corn stover to swine manure enhanced biogas production in both mesophilic and thermophilic anaerobic digestion [27]. More than 50% of the carbon in corn stover was converted to gas. The addition of corn stover had little effect on solids conversion efficiency. The digested solids were high in protein content and gave high digestibility in vitro [27].


264


Josef Marousek [28] on the other hand, studied how to remove hardly fermentable ballast from the maize silage. The hydrolysis products were squeezed out from the lignocellulose ballast by the rotary dewatering press. The rigid briquettes from the ballast at the rotary dewatering press were charcoaled. Josef Marousek reported that anaerobic fermentation of the maize silage from the hardly fermentable ballast provided 316.7 m3 CH4 VS t−1 per 200 h fermentation in a long-time average. On the other hand, the charcoaled ballast provided 27.506 MJ kg−1, accordingly [28]. Biological treatment of corn stover [28] produced 33.07% more total biogas yield, 75.57% more methane yield, and 34.6% shorter technical digestion time compared with the untreated sample [29]. The effects of corn stover as a supplemental feed on anaerobic digestion of dairy manure under different hydraulic retention times (HRT) was investigated [30]. The results revealed that both hydraulic retention times and corn stover supplement significantly influenced microbial community and the corresponding anaerobic digestion performance. The highest biogas production of 497 mL per gram total solid loading per day was observed at a hydraulic retention times of 40 days from digestion of manure supplemented with corn stover [30]. In another study [31], enzymes (laccase, manganese peroxidase and versatile peroxidase) and different incubation times, (0, 6 and 24 h) were used in the pre-treatment of corn stover for biogas production. The laccase enzyme showed an increase in biomethane production of 25% after 24 h of incubation whereas pre-treatment with peroxidase enzymes increased the biomethane production with 17% after 6 h of incubation [31]. The effect of biological and chemical pretreatment using liquid fraction of digestate (LFD), ammonia solution (AS), and NaOH was investigated on mesophilic anaerobic codigestion of cattle manure and corn stover and the results obtained showed that liquid fraction of digestate pretreatment could achieve the same effect as the ammonia and sodium hydroxide pretreatment at the performance of anaerobic digestion [32]. Simona Menardo and the co-workers [33] identified the most productive part of maize waste (maize cobs, husks, leaves, and stalks). Husks displayed the best results in terms of methane yield [33]. Amon et al., [12] produced biogas from maize digestion and dairy cattle manure. They measured methane production in 1-liter eudiometer batch digester operating at 38°C for 60 days. The results showed that the manure from dairy cows with medium milk yield gave the largest specific methane yield of 166.3 Nl CH4 kg VS-1. Thirteen early to late ripening maize varieties were grown on a number of locations in Austria, experiments were performed in order to evaluate the ripening effect on the methane yield. The results showed that late ripening varieties gave more biomass than medium or early ripening varieties but the methane yield declined as the crop approaches full ripeness. Late ripening maize varieties yield ranged between 312 and 365 Nl CH4 kg VS-1 (milk ripeness) and 268-286



265

Nl CH4 kg VS-1 (full ripeness), respectively. The experimental results also showed that silaging improved the methane yield by about 25% when compared to green non-conserved maize. With early to medium ripening varieties (FAO 240-390), the optimum harvesting time was at the ‘‘end of wax ripeness’’. Late ripening varieties (FAO ca. 600) were harvested later towards ‘‘full ripeness’’ and the maximum methane yield per hectare from late ripening maize varieties ranged between 7100 and 9000 Nm3 CH4 ha-1. Early and medium ripening varieties, on the other hand yielded 5300-8500 Nm3 CH4 ha-1 when grown in favorable regions. Also, the highest methane yield per hectare was achieved from digestion of the whole maize crops as opposed to corn cob mix. When corn cob mix was used, a decrease in the methane yield per hectare of 70 and 43% was obtained. Biogas production from maize hybrids was investigated by Oslaj et al., [4]. Their work aimed at optimizing the anaerobic digestion of maize using a laboratory digester to identify the maturity class of corn and respective hybrid which would give the highest rate of biogas and biomethane. The corn hybrids of FAO 300-FAO 400, FAO 400-FAO 500 and FAO 500-FAO 600 maturity classes were tested. The experimental results indicated that the highest maturity class of corn (FAO 400, FAO 500) increased the amount of biomethane. The greatest gain of biomethane per hectare according to maturity class was found with hybrids of FAO 400 (7768.4 Nm3 ha-1) and FAO 500 (7050.1 Nm3 ha-1) maturity classes, respectively. Among the corn hybrids of maturity class FAO 300-FAO 400, the hybrid PR38F70 gave the greatest production of biomethane per hectare (7646.2 Nm3 ha-1). The production of biomethane varied with corn hybrids from 50 to 60% of biogas produced [4]. An investigation on the anaerobic digestion of maize waste which was indiscriminately dumped on Nigerian urban streets was carried out [34]. The potential of different parts of maize waste (chaffs, stalks and cobs) to produce biogas was examined. The waste was then mixed with water at a water: waste ratio ranging between 3:1 and 4:1. The resulting mixture was anaerobically digested in three separate 0.1 m3 digesters for 30 days. The physcochemical and microbiological analyses of the digesting substrates were carried out over 30 days retention period to assess the progress of digestion. The results obtained showed that the chaffs produced more biogas than the other parts of maize wastes even though maize chaffs, stalks and cobs have the potential to generate biogas. It was also observed that the chaffs generated more methane gas than the other two and was the earliest to flame when tested [34]. Lebuhn et al., [35] investigated biogas production from mono-digestion of maize silage. The experiment was performed for more than one year in six continuously stirred daily fed 36 L fermenters. The researchers involved in this work concurrently analyzed chemical and microbiological parameters. The reactors acidified after eight months of operation at a low organic loading rate (OLR) of 2 g VS*(L*d) −1. The TVA/TAC. Their investigations showed that the most limiting element in long-term mono-digestion of maize silage was cobalt [35].


266


Strik et al., [36] on the other hand, investigated a pH-based control of ammonia in biogas during anaerobic digestion of artificial pig manure and maize silage. The experimental results proved that ammonia can be present in biogas from anaerobic digestion and the reactor pH can be monitored to control it. Biogas containing ammonia was produced for a period of more than 100 days with a maximum of 332 ppm. Free ammonia was effectively reduced to less than the inhibition level, 9ppm by pH-based control. In carrying out this study, it was shown that high ammonia concentrations lead to a range of problems including (1) process inhibition; (2) decreased COD removal efficiency; (3) reduced biogas production, to mention but a few [36]. Several biological ensilage additives were tested on maize substrate for their effect on biogas production and preservation of ODM content [37]. In general, the addition of some biological additives and subsequent storage for 7 weeks proved to have a capacity to enhance the biogas and biomethane production per ODM when compared to the untreated samples. A common microbial inoculant containing homo-fermentative and heterofermentative bacteria had no beneficial effect on biogas and biomethane production compared with the untreated sample. More complex additives with hetero- and homofermentative activity as well as enzymes or bacteria and yeasts effectively increased biogas production per ODM. Losses in ODM content were minor in all samples. The results indicated that more divergent biological additives involving yeasts or enzymes during ensiling are preferred as maize preservation tools for anaerobic digestion instead of a spontaneous ensilage [37]. Pobeheim et al., [38] studied the importance of nickel and cobalt on anaerobic degradation of a defined model substrate for maize. The experiment was done by operating five semi-continuous reactors for 250 days at 35°C and a well-defined trace metal solution was added to all reactors. Two reactors each were limited regarding the concentration of Ni2+ and Co2+ for certain time periods. The required nickel concentration was depending on the organic loading rates (OLR) while, for example, above 2.6 g ODM L-1d-1 nickel concentrations below 0.06 mg kg-1 FM in the process significantly reduced biogas production by up to 25% compared to a control reactor containing 0.8 mg Ni 2+ kg-1 FM. Similarly, limitations of cobalt to 0.02 mg kg-1 FM reduced biogas production by about 10%. However, after gradual addition of nickel and cobalt, the organic loading rate was again improved to 4.3 g ODM L-1d-1 while process stability was recovered and a fast metabolisation of acetic and propionic acid was detected. It was reported somewhere [39] that although the anaerobic digestion of animal manure is regarded as the most beneficial for reducing greenhouse gas emissions from manure storage, the energy output can be substantially enhanced by co-digesting manure and maize, which is the most efficient crop for substrate provision in many regions. Key challenges that have been identified to enhance the sustainability of maize-based biogas production included: (1) the design of regionally adapted maize rotations; (2) an improved management of biogas residues (BR); (3) the establishment of a more comprehensive data



267

base for evaluating soil in maize production as well as greenhouse gas emissions at the biogas plant and (4) the consideration of direct and indirect land use change impact of maize-based biogas production [39], respectively. In another study [40], the effect of drought stress on yield and quality of maize/sunflower and maize/sorghum intercrops for biogas production was investigated. Maize was intercropped with either sunflower or forage sorghum to determine the effect of seasonal water supply on yield and quality of the above-ground biomass as a fermentation substrate. The two intercrop partners were grown in alternating double rows at plant available soil water levels of 60–80%, 40–50% and 15–30% under a foil tunnel during the years 2006 and 2007 at Braunschweig, Germany. Although the intercrop dry matter yields in each year increased with increasing soil moisture, the partner crops responded quite differently. While maize produced significantly greater biomass under high rather than low water supply in each year, forage sorghum exhibited a significant yield response only in 2006, and sunflower in none of the 2 years. Despite greatly different soil moisture contents, the contribution of sorghum to the intercrop dry matter yield was similar, averaging 43% in 2006 and 40% in 2007. Under conditions of moderate and no drought stress, sunflower had a dry matter yield proportion of roughly one-third in both years. In the severe drought treatment, however, sunflower contributed 37% in 2006 and 54% in 2007 to the total intercrop dry matter yield. The comparatively good performance of sunflower under conditions of low water supply is attributable to a fast early growth, which allows this crop to exploit the residual winter soil moisture. While the calculated methane-producing potential of the maize/sorghum intercrop was not affected by the level of water supply, the maize/sunflower intercrop in 2006 had a higher theoretically attainable specific methane yield under low and medium than under high water supply. Nevertheless, the effect of water regime on substrate composition within the intercrops was small in comparison with the large differences between the intercrops. On the other hand, a comprehensive review on biogas production from maize was published [41]. The review addressed the optimization potential for enhancing maize methane yield, especially open dealing with issues pertaining to biogas maize breeding objectives. One of the challenges the authors reported was the precise quantification of maize-specific methane yield, i.e., the methane yield per unit biomass. It was reported that there is still considerable controversy concerning a biogas maize ideotype. But recent research suggests that it differs from the forage maize ideotype, and that a high methane yield can be achieved by different breeding strategies [41]. A model was developed to derive cost curves for the unit costs of biogas and electricity production and for the transport costs for maize silage and biogas slurry in Austria [42]. The least-cost plant capacity was found to depend on the local availability of silage maize, and ranges in the model calculations from 575 to 1150 kWel. In another work, the influence of maize hybrid and harvesting time on biogas production was studied [43]. The experiment was done by carrying out a field trial at the


268


Research and Study Farm “Vecauce” of the Latvia University of Agriculture (LLU) from 2008 to 2010. Ten (in 2008), eleven (in 2009) and fifteen (in 2010) maize hybrids with various maturity rating referring to FAO number (FAO 180 – 340) were harvested at three various times, starting on the 5th of September at fourteen-day intervals. Two hybrids in 2008, three in 2009 and four in 2010 were used for biogas production. The biogas yield per ha of ensiled maize hybrids improved until the final harvest date [43]. Vindis et al., [44] on the other hand, investigated the impact of mesophilic and thermophilic anaerobic digestion on biogas production. In their work, they compared mesophilic and thermophilic anaerobic digestion of three maize varieties. They measured and calculated parameters like biogas production and biogas composition from maize silage. The results showed that biogas yields ranged between 315-409 Nl kg VS-1 in mesophilic conditions and 494-611 Nl kg VS-1 in thermophilic conditions. Thermophilic temperature range showed better biogas quality than mesophilic temperature range. The researchers concluded that thermophilic digestion is four times more intense, has higher VSS removal efficiency and yields more biogas [44]. E. Klimiuk et al., [45] investigated methane productivity of silage of four crop species Zeamays L., Sorghumsaccharatum, Miscanthus × giganteus and – Miscanthussacchariflorus, respectively. The results showed that due to higher crude fiber content in Miscanthus spp at a hydraulic retention time of 60 days, the volumetric methane yields from the Z. Mays L. or S. Saccharatum silages were better than those from the Miscanthus × giganteus or M. sacchariflorus silages. Though, at comparable lignin concentrations in the feedstock, methane productivity for M. sacchariflorus (0.19 ± 0.08 L/g volatile solids) was two times that of Miscanthus × giganteus (0.10 ± 0.03 L/g volatile solids). The efficiency of cellulose conversion differed from 83.6% (S. Saccharatum) to 52.1% (Miscanthus × giganteus), and hemicellulose from 88.9% (Z. mays L.) to 59.7% (Miscanthus × giganteus), respectively. Conversion of cellulose and hemicellulose depended on the ratio of the polysaccharides to the lignin concentration of the feedstock [45]. Amon et al., [46] investigated the impact of variety and time of harvest on the methane yield. Their aim was to optimize anaerobic digestion of maize and clover grass. They estimated that a maximum methane yield per hectare should be achieved with energy crops. The obtained results showed that maximum methane yield from late ripening maize varieties ranged between 7100-9000 Nm3 CH4 ha-1. Early and medium ripening varieties yielded 5300-8500 Nm3 CH4 ha-1 when grown in favorable regions [46]. Asam et al., [47] on another work, carried out their research in laboratory scale batch digesters to assess the biogas potential of energy crops (maize and grass silage) and solid manure fractions from manure separation units. They determined the ultimate methane productivity in terms of volatile solids (VS) as 330, 161, 230, 236, 361 L/kg VS from raw pig slurry, filter pressed manure fiber (FPMF), chemically precipitated manure fiber (CPMF), maize silage and grass silage, respectively. Methane productivity based on mass



269

(L/kg substrate) was significantly higher in filter pressed manure fiber (55 L/kg substrate), maize silage (68 L/kg substrate) and grass silage (45–124 L/kg substrate (depending on dry solids of feedstock) when compared to raw pig slurry (10 L/kg substrate). The use of these materials as co-substrates with raw pig slurry significantly raised the biomethane yield per unit feedstock in the biogas plant [47]. S. González-García et al., [48] on their work entitled “Comparative environmental performance of three different annual energy crops for biogas production in Northern Italy” cultivated three different energy crops which were; wheat, maize and triticale, for biomass in order to produce biogas in Lombardy, in the Po Valley (Italy) [48]. They quantified their environmental profiles and determined the best biomass source from an environmental perspective. The choice of these cropping systems was based on the fact that they are wellknown and extensively cultivated for energy purposes in Italy. The standard framework of the Life Cycle Assessment (LCA) was followed in this study and detailed inventories for these crops were designed. The environmental profile was analyzed in terms of abiotic depletion, acidification, Eutrophication, global warming, ozone layer depletion, photochemical oxidants formation, human toxicity and ecotoxicity. In addition, an energy analysis was performed using the cumulative energy demand method. The results revealed that the selection of the best biomass source depends on several factors such as the functional unit and biomass yield. Thus, a sensitivity assessment was done in order to determine these variations. Furthermore, the most significant processes throughout the life cycle of the cropping systems were identified and improvement alternatives were proposed, specifically for the mineral fertilization. Thus, different scenarios built on alternative nitrogen based fertilizers were assessed in detail and discussed, resulting in the identification that the use of calcium ammonium nitrate instead of urea should improve the environmental profile regardless of the energy crop. Finally, the combination of triticale or wheat with maize classes 300, 400 and 500 in rotation systems was done in order to achieve similar biomass yields, per ha, to the maize classes 600 and 700, which were also evaluated. The best results were obtained for maize classes 600 and 700 regardless of the functional unit considered in all the categories assessed except in GWP, where triticale with maize 400 and with maize 500 were the best options [48]. Gissen et al., [49] compared energy crops for biogas production-yields, energy input and costs in cultivation using digestate and mineral fertilization. Six crops grown in Southern Sweden were analyzed for biogas production which were; hemp, sugar beet, maize, triticale, grass/clover ley and winter wheat [49]. The maximum biomass and biogas yield was experimented for sugar beet. Crops with lower risk of negative environmental effect in cultivation, such as ley and hemp, showed less than half the methane energy yield per hectare. Triticale also showed less risk of negative environmental effect but gave similar energy yield as winter wheat grain and maize [49]. Nges et al., [50] investigated the benefits of supplementing an industrial waste anaerobic digester with energy crops to increase biogas production. They examined the


270


feasibility of supplementing a protein/lipid-rich industrial waste (pig manure, slaughterhouse waste, food processing and poultry waste) mesophilic anaerobic digester with carbohydrate-rich energy crops (hemp, maize and triticale) in laboratory scale batch and continuous stirred tank reactors (CSTR) with a view to scale-up to a commercial biogas process [50]. The results showed that co-digesting industrial waste and crops led to significant increase in methane yield per ton of feedstock and carbon-to-nitrogen ratio as compared to digestion of the industrial waste alone. Biogas production from crops in combination with industrial waste also prevents the need for micronutrients normally needed in crop digestion [50]. Mahnert and Linke, [51] studied reactor performance data in long‐term semi‐ continuous laboratory‐scale experiments with maize silage, whole‐crop rye silage and fodder beet silage as mono‐substrate and cattle slurry at mesophilic temperatures [51]. For calculation of a biogas yield as the function of the organic rate loading, a hyperbolic equation was developed on the base of a first‐order reaction rate for substrate degradation. The biogas yield depends also on the concentration of volatile solids of the input, the density of the effluent, the density of the biogas and the reaction rate constant, which are all substrate or process specific. Values of the theoretical maximum biogas yield and the reaction rate constant were observed in the range of 0.61-0.93 m3 per kg volatile solids and 0.032 - 0.316 d−1, respectively [51].

CONCLUSION Maize is the mostly used crop in biogas production, globally. It is thought to have the top yield potential of field crops grown in developing as well as developed countries. Climate, location and maize diversity are vital in biogas generation from maize crop. The single largest category of crops is maize, which has the highest global production reported so far. High production rate of maize due to growth population increases maize waste generated, correspondingly. Whenever maize waste remains after harvest, it is either decomposed, eaten by termites, or burned in the open field prior to the planting season. Biomass burning has a significant impact on global atmospheric chemistry since it provides large sources of carbon monoxide, nitrogen oxides, and hydrocarbons, primarily in the tropics. These gases are precursors of tropospheric ozone and influence the chemistry of the OH radical. As the developing world population continues to rise, the contributions from these types of biomass burning increase. Therefore, much more value addition to maize wastes is required to develop new commercial products to meet the local demand. Innovative strategies are still required in this regard to mitigate these effect cost effectively. Maize crops and maize waste have a huge unutilized potential to meet the energy demand in South Africa. Likewise, in order to generate renewable energy in a sustainable way, the energy efficient fermentation of maize crops/waste seems to be the best idea for developed



271

as well as developing countries. It would be economic and would contribute to environmental protection. Most researchers have found methane fermentation technology to be the most efficient way of maize crop and maize waste utilization for energy generation in term of energy output/input ratio among all the biological and thermo-chemical routes of energy conversion processes.

REFERENCES [1]

Vindis P, Mursec B, Janzekovic M, Cus F. Processing of soybean meal into concentrates and testing for Genetically Modified Organism (GMO). Journal of Achievements in Materials and Manufacturing Engineering, 20 (2007) 507-510. [2] Amon T, Amon B, Kryvoruchko V. Methane production through anaerobic digestion of various energy crops grown in sustainable crop rotations. Bioresource Technology, 98 (2007) 3204-3212. [3] Chynoweth, D.P., 2004. Biomethane from energy crops and organic wastes. In: International Water Association (E/ds.), Anaerobic Digestion 2004. Anaerobic Bioconversion. Answer for Sustainability, Proceedings 10th World Congress, vol. 1, Montreal, Canada. www.ad2004montreal.org, pp. 525-530. [4] Oslaj M, Mursec B, Vindis P. Biogas production from maize hybrids. Biomass and bioenergy, 34 (2010) 1538-1545. [5] Balsari P, Bonfanti P, Bozza E, Sangiorgi F. Evaluation of the influence of animal feeding on the performances of a biogas installation (mathematical model). In: Third international symposium on anaerobic digestion. Boston; 1983: p. 7. [6] National Non-Food Crops Centre. “NNFCC Renewable Fuels and Energy Factsheet: Anaerobic Digestion”, Retrieved on 2011-02-16. [7] “Biogas & Engines” www.clarke-energy.com. Retrieved 21 November 2011. [8] Chynoweth, DP, Turick, CE, Owens, JM, Jerger, DE, Peck, MW, Biochemical methane potential of biomass and waste feedstocks. Biomass Bioenergy, 5 (1) (1993) 95-111. [9] Gunaseelan, VN. Anaerobic digestion of biomass for methane production: a review. Biomass Bioenergy, 13 (1-2) (1997) 83-114. [10] Weiland, P. Production and energetic use of biogas from energy crops and wastes in Germany. Appl. Biochem. Biotechnol, 109 (2003) 263-274. [11] Amon, T, Kryvoruchko, V, Bodiroza, V, Amon, B. Methanerzeu-gung aus Getreide, Wiesengras und Sonnenblumen. Einfluss des Erntezeitpunktes und der Vorbehandlung. [Methane production from cereals, meadow grass and sunflowers. Influence of harvest time and pretreatment.] In: 7. Tagung: Bau, Technik und Umwelt in der landwirtschaftlichen Nutztierhaltung 2005, Herausgeber: Kuratorium fu¨r


272

[12]

[13]

[14] [15]

[16] [17] [18] [19]

[20]

[21]

[22]

[23]

[24] [25]

Linda Z. Linganiso, Amanda Phungula, Tshwafo E. Motaung et al. Technik und Bauwesen in der Landwirtschaft e.V. (Ed.), pp. 343–348. http://www. nas.boku.ac.at/4536.html. Amon, T, Amon, B, Kryvoruchko, V, Zollitsch, W, Mayer, K, Gruber, L. Biogas production from maize and dairy cattle manure - Influence of biomass composition on the methane yield. Agriculture, Ecosystems and Environment, 118 (2007) 173182. Chandra, R, Takeuchi, H, Hasegawa T. Methane production from lignocellulosic agricultural crop wastes: A review in context to second generation of biofuel production. Renewable and Sustainable Energy Reviews, 16 (2012) 1462-1476. Deublein D, Steinhauser A. Biogas from waste and renewable sources: an introduction. Weinheim: WILEY-VCH Verlag GmbH & Co. KGaA; 2008. Miroslav Hutňan, Viera Špalková, Igor Bodík, Nina Kolesárová, Michal Lazor. Biogas Production from Maize Grains and Maize Silage. Polish J. of Environ. Stud., 19(2)(2010) 323-329. https://www.nass.usda.gov/Publications/Ag_Statistics/2008/2008.pdf. https://www.iea.org/publications/freepublications/publication/WEO2015SpecialRe portonEnergyandClimateChange.pdf. https://encyclopedia2.thefreedictionary.com/National+Income+Statistics. Pang, YZ, Liu, YP, Li, XJ, Wang, K S, Yuan, HR. Improving Biodegradability and Biogas Production of Corn Stover through Sodium Hydroxide Solid State Pretreatment. Energy Fuels, 2008, 22 (4), pp 2761–2766, DOI: 10.1021/ef800001n. Xiujin Li, Laiqing Li, Mingxia Zheng, Guozhi Fu and Jam Saifullah Lar. Anaerobic Co-Digestion of Cattle Manure with Corn Stover Pre-treated by Sodium Hydroxide for Efficient Biogas Production. Energy Fuels, 23 (9) (2009) 4635-4639, DOI: 10.1021/ef900384p. Mingxia Zheng, Xiujin Li, Laiqing Li, Xiaojin Yang, Yanfeng He. Enhancing anaerobic biogasification of corn stover through wet state NaOH pre-treatment, Bioresource Technology, 100 (2009) 5140 -5145. Yeqing Li, Ruihong Zhang, Xiaoying Liu, Chang Chen, Xiao Xiao, Lu Feng, Yanfeng He, and Guangqing Liu. Evaluating Methane Production from Anaerobic Mono- and Co-digestion of Kitchen Waste, Corn Stover, and Chicken Manure. Energy Fuels, 2013, 27 (4), pp 2085–2091, DOI: 10.1021/ef400117f. Yebo Li, Stephen Y Park, and Jiying Zhu. Solid-state anaerobic digestion for methane production from organic waste. Renewable and Sustainable Energy Reviews, 15(1) (2011)821-826. Zhen-Hu Hu and Han-Qing Yu. Application of rumen microorganisms for enhanced anaerobic fermentation of corn stover. Process Biochemistry 40 (2005) 2371-2377. Wenyao Jin, Xiaochen Xu, Yang Gao, Fenglin Yang, Gang Wang. Anaerobic fermentation of biogas liquid pre-treated maize straw by rumen microorganisms in vitro. Bioresource Technology, 153 (2014) 8-14.



273

[26] Yeqing Li, Ruihong Zhanga, Yanfeng Hea, Chenyu Zhanga, Xiaoying Liua, Chang Chen, Guangqing Liu. Anaerobic co-digestion of chicken manure and corn stover in batch and continuously stirred tank reactor (CSTR). Bioresource Technology, 156, (2014)342-347. [27] Fujita, M, Scharer JM, Moo-Young M. Effect of corn stover addition on the anaerobic digestion of swine manure. Agricultural Wastes, 2 (1980) 177-184. [28] Josef Marousek. Removal of hardly fermentable ballast from the maize silage to accelerate biogas production. Industrial Crops and Products, Industrial Crops and Products, 44 (2013) 253-257. [29] Weizhang Zhong, Zhongzhi Zhang, Yijing Luo, Shanshan Sun, Wei Qiao, Meng Xiao. Effect of biological pre-treatments in enhancing corn straw biogas production. Bioresource Technology, 102 (2011) 11177-11182. [30] Zhengbo Yue, Rui Chen, Fan Yang, James MacLellan, Terence Marsh, Yan Liu, Wei Liao. Effects of dairy manure and corn stover co-digestion on anaerobic microbes and corresponding digestion performance. Bioresource Technology, 128 (2013) 6571. [31] Michel Schroyen, Han Vervaeren, Stijn W.H. Van Hulle, Katleen Raes. Impact of enzymatic pre-treatment on corn stover degradation and biogas production. Bioresource Technology, 173 (2014) 59-66. [32] Yufang Wei, Xiujin Li, Liang Yu, Dexun Zou, Hairong Yuan. Mesophilic anaerobic co-digestion of cattle manure and corn stover with biological and chemical pretreatment. Bioresource Technology, 198 (2015) 431-436. [33] Simona Menardo, Gianfranco Airoldi, Vincenzo Cacciatore, Paolo Balsari. Potential biogas and methane yield of maize stover fractions and evaluation of some possible stover harvest chains. Biosystems Engendering 129 (2015) 352 -259. [34] Eze, JI, Ojike, O. Anaerobic production of biogas from maize wastes. International Journal of Physical Science, 7(6), 2012, 982-987. [35] Lebuhn, M, Liu, F, Heuwinkel, H, Gronauer A. Biogas production from monodigestion of maize silage–long-term process stability and requirements. Water Science and Technology, 58 (8) (2008) 1645-1651. [36] Strik, DP, Domnanovich, AM, Holubar P. A pH-based control of ammonia in biogas during anaerobic digestion of artificial pig manure and maize silage. Process Biochemistry 41 (2006) 1235-1238. [37] Vervaeren, H, Hostyn, K, Ghekiere, G. Willems B. Biological ensilage additives as pretreatment for maize to increase the biogas production. Renewable Energy, 35 (2010) 2089-2093. [38] Pobeheim, H, Munk, B, Lindorfer, H, Guebitz GM. Impact of nickel and cobalt on biogas production and process stability during semi-continuous anaerobic fermentation of a model substrate for maize silage. Water research, 45 (2011) 781787.


274


[39] Herrman, A. Biogas Production from Maize: Current State, Challenges and Prospects. Agronomic and Environmental Aspects. Bioenerg. Res., 6 (2013) 372387. [40] Schittenhelm S. Effect of Drought Stress on Yield and Quality of Maize/Sunflower and Maize/Sorghum Intercrops for Biogas Production. Journal of Agronomy and Crop Science, 196 (4), 2010, 253-261. [41] Herrman, A, Rath J. Biogas Production from Maize: Current State, Challenges, and Prospects. 1. Methane Yield Potential. Bioenerg. Res., 5 (2012) 1027-1042. [42] Walla, C, Schneeberger, W. The Optimal Size for Biogas Plant. Biomass and Bioenergy, 32(6), 2008, 551-557. [43] Bartusevics, J, Galie, Z, Strikauska, S. Biogas production from maize. Jelgava (Latvia), 23(24) (2012)1-246. [44] Vindis, P, Mursec P, Janzekovic, P, Cus, F. The impact of mesophilic and thermophilic anaerobic digestion on biogas production. Journal of Achievements in Materials and Manufacturing Engineering 36/2 (2009) 192-198. [45] Klimiuk E, Pokój, T, Budzynski, W, Dubis, B. Theoretical and observed biogas production from plant biomass of different fibre contents. Bioresource energy, 101/24 (2010) 9527-9535. [46] Amon, T, Kryvoruchko, V, Amon, B, Zollitsch, W, Pötsch, E. Biogas production from maize and clover grass estimated with the methane energy value system. Conference Proceedings. 2004. [47] Asam, ZZ, Poulsen, TG, Nizami, AS, Rafique, R, Kiely, G, Murphy, JD. How can we improve biomethane production per unit of feedstock in biogas plants? Applied Energy, 88 (2011) 2013–2018. [48] González-García, S, Bacenetti, J, Negri, M, Fiala, M, Arroja, L. Comparative environmental performance of three different annual energy crops for biogas production in Northern Italy. Journal of Cleaner Production, 43 (2013) 71-83. [49] Gissen, C. Prade T, Kreuger, E, Nges, IA, Rosenqvist, H, Svensson, SE, Lantz, M, Mattsson, JE, Borjesson, P, Bjornsson L. Comparing energy crops for biogas production-Yields, energy input and costs in cultivation using digestate and mineral fertilisation. Biomass and Bioenergy, 64 (2014) 199-210. [50] Nges, IA, Escobar, F, et al. Björnsson. Benefits of supplementing an industrial waste anaerobic digester with energy crops for increased biogas production. Waste Management 32 (2012) 53-59. [51] Mahnert P, Linke B. Kinetic study of biogas production from energy crops and animal waste slurry: Effect of organic loading rate and reactor size. Environmental technology, 30/1 (2009) 93-99.




Chapter 13

WASTE BRICK APPLICATIONS Tshwafo E. Motaung*, Amanda Phungula and Linda Z. Linganiso Department of Chemistry, University of Zululand, KwaDlangezwa, KwaZulu Natal, South Africa

ABSTRACT Bricks are materials used worldwide in building and construction sector. In ancient times, bricks were made using clay by human hands and they were left to dry in the sun. Other types of bricks such as compressed earth brick (CEB) have been developed, which are more advantageous as compared to other types. While a building is being built, some bricks are broken and can no longer be used in that building, as a results, they are considered as “waste bricks”. The waste bricks are used to produce other useful products such as replacement of cement in mortar, aggregate in the manufacturing of paving blocks, pavement sub-base materials, etc. Waste bricks can also be used in the production of other new bricks, which can be used again in building and construction sectors. There are many other applications of waste bricks and this chapter focuses on them. It will also report on regulations and policies of waste bricks and give highlights on the market structure and demand.

Keywords: waste brick, building and construction sector, compressed earth brick

1. INTRODUCTION Bricks are materials which are used widely in the construction and building sectors across the globe. Traditionally, bricks are made using clay. They are formed by hand and *

Corresponding author: Email: [email protected].


276

Tshwafo E. Motaung, Amanda Phungula and Linda Z. Linganiso

are left to dry in the sun or fired in a kiln. Once the blocks of clay are ready, they are stacked together and secured in place with mortar [1]. The earliest known bricks were found in the Middle East and were around 7,000 years old. Today, bricks are more likely to be made of shale, a lightweight rock which is easy to break apart to form other substances. Unlike clay bricks which are generally made by means of human hands, these ones require machines for handling, shaping and drying. Given their adequate appearance and durability, bricks remain very popular construction materials due to the fact that they are good insulators, pest resistant and fireproof. Bricks can also be constructed out of concrete, using a blend of calcium and silicone, which produces a light-coloured brick flecked with sparkly bits of stone [2]. Mining shale and other virgin materials required to make bricks are costly and bad for the environment. But when the same material is reused, it will cut down on mining, which is a win for the environment. Construction and Demolition (C&D) materials take up a huge amount of space in landfills. Keeping them out conserves space and prevents more landfills (or incinerators) from being built. Bricks fall into a category known as “construction and demolition” waste. For years, the only form of waste management system which was put in place to dispose of waste bricks was the landfill site. At that time, solid waste management companies started to get smart about how much space bricks, concrete and other construction debris took up. Not only are demolition materials heavy and bulky, but there are also a lot of them out there. A report from a study conducted in California in 2008 showed that construction waste contributes to 29% of the state’s total waste stream [2]. There are salvage companies that will pay people for used bricks. Some customers like the shabby-chic appearance of old blocks or may want bricks that match a structure built many years ago. Vintage Brick Salvage in Rockford, IL, and Experienced Brick & Stone in Amherst, NY, are a few examples of companies which buy used bricks. Places that sell used building materials, such as Habitat for Humanity ReStores, also want recycled bricks [2]. The recycled brick can be crushed and used for a number of different applications. Companies often purchase it instead of aggregate (such as gravel) for construction projects. Bricks can be chipped and used in landscapes. Like the parent material, the chips look satisfactory and will hold up well even in very cold, windy or rainy climates. If the bricks are broken down to a very fine material, they can be used in place of sand or even go into new bricks. Sioux City Brick in Iowa makes a fine brick powder that can be used in baseball diamonds or running tracks [3]. The use of waste brick as waste material can lead to additional benefits in terms of cost reduction, saving energy, ecological balance promotion and natural resources conservation.


Waste Brick Applications

277

2. POLICIES AND REGULATIONS The definition of waste derived from NEM: WA states that: “Waste means any substance, whether or not that substance can be reduced, re-used, recycled or recovered: that is in surplus, unwanted, rejected, discarded, abandoned or disposed of, which the generator has no further use of for the purposes of production that must be treated or disposed of. The management of waste in South Africa has been based on the principles of the waste management hierarchy (Figure 1) from early waste policy (DEAT 2000) and entrenched in recent waste legislation. The adoption of the hierarchy has been in the policy since 2009, but the management of waste has not necessarily followed the hierarchal approach [3]. The waste management hierarchy approach state that waste must be avoided, reduced, re-used, recycled, recovered, treated, disposed and also be legalised. The first point which is avoidance and reduction of waste states that the products and materials must be designed in a manner that minimizes their waste components or in a manner that reduces the natural material amounts used and potential toxicity of waste generated during the production, and after use; materials can be used for similar or different purposes without changing form or properties. This approach seeks to re-use a product when it reaches the end of its life span. In this way, it becomes an input for new products and materials. The process of recycling involves separating materials from the waste stream and processing them as products or raw materials. The first elements of the waste management hierarchy are the foundation of the cradle-to-cradle waste management approach. Waste can also be recovered by reclaiming particular components or materials or using the waste as a fuel. Treatment and disposal is a ‘last resort’ within the waste hierarchy. Treatment refers to any process that is designed to minimize the environmental impact of waste by changing the physical properties of waste or separating out and destroying toxic components of waste. Disposal refers specifically to the depositing or burial of waste onto, or into land. To legalise the waste, processing, treatment, and disposal must take place in accordance with the principles of environmental justice and equitable access to environmental services as articulated in the NEMA [3]. This chapter focuses on construction and demolition waste specifically waste brick so if the word “waste” is used it is referring to waste brick [3].

3. MARKET AND DEMAND A policy and regulatory environment does not actively promote the waste management hierarchy. This has limited the economic potential of the waste management


278


Figure 1. Waste management hierarchy as per the National Waste Management Strategy [3].

sector, which has an estimated turnover of approximately R10 billion per annum. Both waste collection and the recycling industry make meaningful contributions to job creation and GDP, and they can expand further [3]. Despite South Africa’s positive economic trajectory, unemployment remains rife amongst skilled and unskilled people. This has led to government encouraging all sectors to quantify potential employment opportunities that can be created whilst rendering services. Given the nature of the waste sector, there are hidden opportunities that need to be unlocked, in order for this sector to contribute significantly to job creation. An approximation is that, about 70% of solid waste expenditure is through the public sector, largely local government, while 30% is private sector expenditure [4]. Figure 2 provides an estimate employment creation of 113,505 by the total waste sector. The National Treasury has identified municipal solid waste management as one of the areas of municipal functioning with the greatest potential for job creation, particularly with respect to unskilled or semi-skilled labour [3]. The waste management service functions within municipalities, contributing significantly towards municipal revenue due to the user-pays principle applied for waste management. Of the total annual income received by municipalities in 2007 and 2008 (Table 1), income from waste (refuse and sanitation) accounted for 7% and 6.5%, respectively [4]. According to StatsSA’s non-financial census of municipalities, there has been an 8% increase in revenue collected from refuse removal charges in South African municipalities between 2007 and 2008 [4].



279

Figure 2. Waste sector employment estimates [3].

Table 1. Financial census of Municipalities [4] Income Refuse removal charges Sewerage and sanitation charges Property rates received Grants and subsidies received Water sales Electricity and gas sales Other income Total

2007 R million Contribution 3,225 2.9 4,475 4.1 18,331 29,244 11,595 25,589 17,666 110,123

16.6 26.6 10.5 23.2 16.0 100.0

2008 R million Contribution 3,476 2.7 4,875 3.8 20,956 35,535 12,562 27,880 22,347 127,630

16.4 27.8 9.8 21.8 17.5 100.0

4. RECENT RESEARCH AND DEVELOPMENT This section will focus on a brief summary of the recent researches performed where much more value addition to waste brick was done in order to develop different value added products. A. Naceri et al., [5] performed a study to investigate the utilization of waste brick as an alternative material for cement in the cement mortar production. Various proportions (0%, 5%, 10%, 15% and 20% by weight for cement) of waste brick were used to replace the clinker. The examination of the physical and chemical properties of cement at anhydrous phase and the hydrated phase for the mortar were conducted. The analyses demonstrated that the addition of artificial pozzolan increased the grinding time and setting times of the cement, therefore the mechanical properties of mortar improved significantly.


280


When 10% of waste brick was used to substitute cement, the mechanical strengths of mortar increased. These findings demonstrated the potential use of waste material to generate pozzolanic cement [5]. On the other hand, C.S. Poon et al., [6] investigated the blending of recycled concrete aggregate and crushed clay brick as aggregates in the manufacturing of paving blocks. Their findings showed that incorporating crushed clay brick decreases the density, tensile strength and compressive strength of the paving blocks. Due to high water absorption of crushed clay brick particles, the water absorption of the produced paving blocks was superior compared to that of the paving blocks without crushed clay brick. Even though it was established that crushed clay brick damaged the quality of the produced paving blocks to a certain degree, the paving blocks with 50% crushed clay brick met the minimum requirements according to AS/NZS 4455 and ETWB of Hong Kong (Grade B) for pedestrian areas. Moreover, it was possible to produce paving blocks made with 25% crushed clay brick that fulfilled the compressive strength requirement for paving blocks (Grade B) according to ETWB of Hong Kong for trafficked area [6]. The impact of recycled waste brick material on the strength and mechanical characteristics of the bricks was evaluated [7]. The chemical and mineralogical structures of waste bricks from the C̨orum region in West-Anatolia, Turkey, were studied. After pulverizing, the samples were divided into two categories: (a) passing through a coarse sieve and (b) passing through a fine sieve. To find similar test results, the addition of ratios of the waste (0, 10, 20 and 30% by mass) were added to the raw-brick clay. Standard test procedures were utilized to establish the mechanical characteristics of the bricks at various firing temperatures. The findings suggested that a mass of 30% fine-waste material additive fired at 900°C gave the most promising results, the test sample provided enough strength. [7]. M. O’Farrell et al., [8] investigated pore size distribution of mortar, which consisted of different amounts of ground brick from different European waste brick kinds. Clay brick coming from four European countries was ground to roughly cement fineness and utilized to replace cement in quantities of 0%, 10%, 20% and 30% in standard mortars. The test of pore volume, pore size distribution, threshold radius and strength of these mortars were carried out for curing periods of up to one year. The presence of ground brick (GB) altered the compressive strength of the mortar, presumably due to the dilution effect [8]. Characterization of recycled crushed brick and an assessment of its performance as a pavement sub-base material were investigated in a lab scale set-up [9]. The properties of the recycled crushed brick were compared with the local state road authority specifications in Australia to assess its performance as a pavement sub-base material. The procedures performed included tests such as particle size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio, Los Angeles abrasion loss, pH, organic content, static triaxial, and repeated load triaxial tests. California bearing ratio values were found to satisfy the local state road authority requirements for a lower sub-



281

base material. The Los Angeles abrasion loss value obtained was just above the maximum limits specified for pavement sub-base materials. The repeat load triaxial testing established that crushed brick would perform satisfactorily at a 65% moisture ratio level. At higher moisture ratio levels, shear strength of the crushed brick was found to be reduced beyond the acceptable limits. The geotechnical testing results on the other hand, indicated that crushed brick may have to be blended with other durable recycled aggregates to improve its durability and to enhance its performance in pavement sub-base applications [9]. A. Arulrajah et al., [10] on their work titled “Geotechnical characteristics of recycled crushed brick blends for pavement sub-base applications” presented the findings of a laboratory investigation on the characterization of recycled crushed brick when blended with recycled concrete aggregate and crushed rock for pavement sub-base applications. The engineering properties of the crushed brick blends were compared with typical state road authority specifications in Australia for pavement sub-base systems to ascertain the potential use of crushed brick blends in these applications. The tests performed included particle-size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio (CBR), Los Angeles abrasion, pH, organic content, and repeated load triaxial tests. Laboratory tests were undertaken on mixtures of 10%, 15%, 20%, 25%, 30%, 40%, and 50% crushed brick blended with recycled concrete aggregate or crushed rock. The results showed that up to 25% crushed brick could be safely added to recycled concrete aggregate and crushed rock blends in pavement sub-base applications [10]. In another effort, a comparative study was carried out on the performance of two mixtures utilizing recycled brick powder and limestone filler [11]. The tests conducted included indirect tensile experiments, static and dynamic creep tests, water sensitivity experiments and fatigue experiments. The results showed that the mixture with recycled brick powder had better mechanical properties than the mixture with limestone filler. It was then advised that recycled brick powder must be used as mineral filler in asphalt mixture [11]. A research to investigate the effect of utilizing crushed clay brick as an alternative aggregate in aerated concrete was carried out [12]. Two series of mixtures were designed to investigate the physico-mechanical properties and micro-structural analysis of autoclave aerated concrete and foamed concrete. In each series, natural sand was substituted with crushed clay brick aggregate. In both series, the outcomes indicated a serious reduction in unit weight, thermal conductivity and sound attenuation coefficient while porosity increased. Enhancement on compressive strength of autoclave aerated concrete was observed at 25% and 50% substitute, while in foamed concrete, compressive strength gradually reduced by increasing crushed clay brick aggregate content. A comparatively uniform distribution of pore size in case of foamed concrete with natural sand was observed by scanning electron microscope, while the pores were connected mostly and irregularly for mixes containing a percentage higher than 25% clay brick aggregate [12].


282


On the other hand, K.L. Lin et al., [13] on their work titled “Recycling waste brick from construction and demolition of buildings as pozzolanic materials” investigated the pozzolic attributes of pastes that contain waste brick from building construction and demolition wastes. The TCLP leaching concentrations of waste brick for the target cations or heavy metals were all lower than the current regulatory thresholds of the Taiwan EPA. Waste brick had a pozzolanic strength activity index of 107% after 28 days. It was regarded as a strong pozzolanic material. The compressive strengths of waste brick blended cement (WBBC) that contain 10% waste brick increased from 71.2 MPa at 28 days to 75.1 MPa at 60 days, an increase of approximately 5% over that period. At 28 days, the pozzolanic reaction began, decreasing the amount of Ca(OH)2 and increasing the densification. Tests outcomes indicated that waste brick has a capacity of being a potential pozzolanic material in the partial substitute of cement [13]. A new sorbent system for extracting mercury (II) in existence of oleic acid from aqueous solutions has been investigated [14]. This new sorbent is waste crushed brick acquired from local industries. Variables of the system involved solution pH, sorbent dose and contact time. The adsorption isotherm data followed the Langmuir equation, in which attribute parameters were calculated. Waste crushed brick were found to have a maximum mercury (II) extraction capacity (87mg/g). The effectiveness of waste crushed brick for extracting Hg (II) in existence of oleic acid was tested. The experiments were conducted as a function of initial pH and initial metal ions concentration. The Langmuir isotherms fitted very well with the concentration ranges studied, the dimensionless separation factor indicated that the crushed brick can be utilized in the extraction of Hg(II) from aqueous solution. Accordingly, crushed brick may be utilized to banish Hg(II) species from waste water. I. Demir et al., [15] investigated the sulphate resistance of cement mortars when subjected to various exposure conditions [15]. Cement mortars were assembled using a ground waste brick as a pozzolanic partial substitute for cement at substitute standards of 0%, 2.5%, 5%, 7.5, 10%, 12.5 and 15%, respectively. Mortar specimens were stored below three various conditions: continuous curing in lime-saturated tab water, continuous exposure to 5% sodium sulphate solution, and continuous exposure to 5% ammonium nitrate solution, at a temperature of 20 ± 3ºC, for 7, 28, 90, and 180 days. Prisms with dimensions of 25 × 25 × 285 mm, to dictate the expansions of the mortar samples; and another set of prisms with dimensions of 40 × 40 × 160 mm, were assembled to calculate the compressive strength of the samples. It was dictated that the ground waste brick substituent ratios between 2.5% and 10% reduced the expansion values (180 days). The maximum compressive strength values were obtained with 10% substituent ratio in the tap water, sodium sulphate solution, and ammonium nitrate solution conditions for 180 days [15].



283

In another work, concretes were developed from recycled coarse aggregate from waste brick [16]. Waste brick was utilized to replace natural aggregate after being treated. Workability was assessed through slump and cohesiveness examining, and the results obtained implied that the concrete samples displayed good workability. I. Zong et al., [17] predominately discussed the permeability of recycled concretes composed of fly ash and clay brick waste. Different proportions of recycled coarse aggregates acquired from clay brick waste were utilized to substitute natural coarse aggregates. The properties of natural aggregates and recycled aggregates were studied, and recycled aggregates displayed a maximum porosity. Additionally, the strength of the recycled concrete was reduced due to the incorporation of recycled coarse aggregates. The permeability of water, air and chloride ions was assessed through water absorption, water permeability, air permeability and chloride ion diffusion tests. The results showed that the permeability of water, air and chloride ions increased when recycled coarse aggregates were utilized. Additionally, the recycled concrete containing clay brick waste had increased the porosity and displayed a loose paste matrix, which may be the reason for the increased permeability. S. Sharma et al., [18] have considered the experimental study for construction of paver blocks with partial substitute of cement with brick kiln dust. The results showed good and effective outcomes in the construction of the paver blocks after 15% brick kiln dust utilization [18]. J.M. Kinuthia et al., [19] carried out laboratory investigations to establish the potential use of brick dust in construction. The results acquired showed that partial substitution of the dust with pulverized fuel ash led to a stronger material compared to using it on its own. The blended stabilizers reached better performance. These results suggested technological, economic as well as environmental benefits of utilizing the brick dust and similar industrial by-products to reach sustainable infrastructure development with near zero industrial waste. The results acquired in this research work has shown that stabilizing waste from the cutting of bricks reached serious laboratory strength at 5% stabilizer content. The unconfined compressive strength tests were corroborated by the alternative California Bearing Ratio procedure, which specifically confirmed good resistance to penetration of the material upon soaking in water. It was detected that the lime-stabilized system recorded higher unconfined compressive strength values than Portland cement systems, suggesting viability of the more environmentally friendly utilization of lime as opposed to the utilization of Portland cement, whose manufacture has led to serious emission of carbon dioxide into the atmosphere, coupled with serious consumption of energy and natural raw material resources. The robustness of these systems was further enhanced by the achievement of very low changes in volume upon wetting and soaking in water. This suggests that there is room for further industrial development into viable building and construction materials [19].


284


In another effort, I. Kesegić et al., [20] showed that concrete can be successfully manufactured using recycled aggregates which has been manufactured from demolition and construction waste. The concrete produced with crushed brick aggregate displayed better thermal properties strength [20]. F. Kooli et al., [21] showed that the brick waste could be utilized to extract basic blue 41 dye from aqueous solutions. Some of the results obtained showed that treating brick waste with acid did not enhance the extraction potential of basic blue 41. However, treating the brick waste with base increased its extraction potential two fold. The adsorption capacity reduced from 100% to 10% when the initial concentrations of basic blue and dose of the brick waste increased from 25 to 900 mg/L. The particle size of non-treated brick waste affected the extraction capacity also; more dye was extracted with a smaller particle diameter. The leading experimental equilibrium data were well-represented by the Langmuir isotherm, and the kinetic data fit a pseudo-second order model well. The maximum extraction of basic blue 41 dye was 60-70 mg/g. The extraction potential increased with an increase in the initial concentration, temperature and the mass of brick waste utilized. The pH of the initial dye solution affected the extraction potential at values between 2 and 4 but remained unchanged at maximum pH values. Above pH 10, the basic blue dye reacted with the sodium hydroxide to form a brown precipitate. The chemical treatment of brick waste affected its extraction properties, especially when treated with sodium hydroxide solution; a twofold increase in the removal of basic blue 41 was reached. Treatment with sulphuric acid increased the specific surface area, but this parameter was not crucial for the extraction of basic blue 41; in fact, a decrease in dye extraction was acquired [21]. Other researchers [22] suggested a methodology to estimate the eco-costing of construction waste in order to reduce the influence of waste generated by construction activities. They quantified the ecological cost and investigated the influence of brick waste from construction sites on the environment. Life-cycle assessment methodology and Ecoindicator 95 were utilized to calculate the influence of brick waste. This work supplied a first attempt to conceptualize eco-costing issues in relation to waste from construction activities. Construction project and material specifications contribute enormously to waste generation [22]. Outcomes have indicated that brick waste generation by construction activities could result in serious influences on the environment. Disposal activities during the end of life of bricks such as direct disposal, sorting before disposal and direct recycling contributed to varied percentages of influence. In most cases, the direct disposal option and the sorting activities produced nearly the same influence contribution value with the direct recycling activity [22]. The effects of adding different concentrations, sources and compositions of ground red clay brick waste (RCBW) on the properties of fresh and hardened pastes and mortars of alkali-activated slag was studied [23]. The experimental results showed that the addition of 40% ground red clay brick waste enhanced the 7- and 28-day strength of blended alkali-



285

activated slag pastes and mortars, and can substitute up to 60% of the slag without losing strength [23]. Z. Ge et al., [24] partially substituted cement with ground clay-brick to investigate its effect on the properties of fresh and hardened concrete. In this study, three various substitute standards (10%, 20%, and 30%) and three kinds of clay-brick-powder (CBP) with various particle sizes (Type A, B, and C) were adopted. The experimental outcomes indicated that clay-brick-powder decreased the slump of fresh concrete significantly as the substitute standard was over 10%. All concrete specimens had similar density around 2400–2500 kg/m3. As the substitute standard increased, the early age strength reduced. However, as the curing age increased, the strength of concrete with clay-brick-powder became similar to that of reference concrete. Most concrete containing clay-brick-powder had 90-day compressive strength over 50 MPa, 28-day flexural strength in the range of 1012 MPa, and 28-day splitting tensile strength of 2-4 MPa. Static elastic modulus was between 15 and 30 GPa, respectively. The final outcomes suggested that clay-brick-powder could be utilized to partially substitute cement without compromising the properties of the concrete [24]. T. Aatheesan et al., [25] presented the engineering attributes of different proportions of crushed brick blends with crushed rock acquired from extensive laboratory testing [25]. The engineering properties acquired were compared with existing local road authority specifications for pavement sub-base or light-duty base material and backfill material for drainage systems to discover the capacity use of crushed brick blends. The materials for the experimental works were collected from a recycling facility in Victoria, Australia. The results showed that incorporation of crushed brick into basaltic crushed rock (class 3) has a ‘low to minimal effect’ on the physical and mechanical properties of the original material. The grading limits of all the crushed brick blends studied, before and after compaction, were also within VicRoads specified upper and lower bounds for crushed rock (class 3). The laboratory experiment outcomes indicated that potentially, up to 30% crushed brick could be safely added to crushed rock (class 3) blends for pavement sub-base application. VicRoads initially recommended up to 15% of crushed brick content in crushed rock (class 3) blends, but has stated that depending on the results of field trials, it may be possible to increase the percentage of crushed brick added in the future [25]. In another effort, the effects of recycled clay brick utilized as a part of fine aggregate on mortar durability was investigated [26]. The brick, in crushed form was obtained from a local brick manufacturer that salvages its off-standard products. It was utilized to substitute 10% and 20% (by weight) of the river sand in mortar. Effects of the brick substitution on the mortar flow, compressive strength, shrinkage, freeze–thaw resistance, and alkali-silica reaction capacity were investigated. The outcomes indicated that as the brick substitution standard increased, the mortar flow ability decreased. The 10% and 20% brick replacements had no negative effect on the mortar compressive strength and very scarce effect on the mortar shrinkage. The freeze–thaw resistance of the mortar was


286


enhanced by brick substitution. However, the utilization of crushed brick as aggregate seemed not to decrease potential alkali–silica reaction. The microscopy study showed the alkali–silica reaction product and associated cracking in the mortar. Additional study displayed that the brick aggregate utilized in the study had pessimum proportion, 30%, for the alkali–silica reaction expansion [26]. A study to direct the adsorption of Cr (VI) on a novel low cost carbonaceous material under various experimental conditions such as contact time, initial concentration of metal ions, pH and temperature was performed [27]. The equilibrium data was fitted well with Langmuir and Freundlich isotherms. Adsorption kinetics of Cr(VI) ions onto chimney waste adsorbent were examined by pseudo first order and pseudo second order models. The adsorption procedure was favored by acidic pH and followed the second order kinetics. Various thermodynamic parameters like activation energy (Ea), Gibbs free energy change (∆Go), enthalpy change (∆Ho) and entropy change (∆So) were calculated. The outcomes indicated that the carbonaceous material acquired from bricks kiln chimneys can be efficiently utilized for Cr (VI) removal from wastewater. Adsorption of Cr(VI) on low cost carbonaceous material were investigated under various experimental conditions such as contact time, initial concentration of metal ions, pH and temperature. It was noted that this material has good adsorption capacity for Cr(VI). The equilibrium time for the adsorption of Cr(VI) on activated carbonaceous material was found to be 90 minutes. The adsorption procedure of Cr(VI) was described by Langmuir and Freundlich isotherm models. It was further noted that extraction of Cr(VI) increased with increasing adsorbent dosage and the maximum adsorption of Cr(VI) on material under study was in the pH range 2-4 [27]. Waste clay bricks were also used in concrete preparation [28]. In the first period of the research, clay bricks as waste materials from building remains were collected and ground by jaw mills and finally graded in the range of level sand. The results obtained clearly indicated that in light of some positive effect such as a reduction in the concrete unit weight, recycling the waste materials and also the minimum reduction of compressive strength, utilizing brick waste materials may be considered a suitable choice in concrete, especially in areas close to brick furnaces. It was also reported that the nano SiO 2 can enhance the strength and durability of concrete. Conclusively, utilizing waste bricks can be an effective measure in sustainable growth. There is no significant issue to utilize brick as sand in optimal percents in terms of mechanical properties like compressive strength. However, due to higher water absorption, a long observation is necessary. It was suggested that 25% brick sand is the optimum. Utilizing nano SiO2 along with brick waste materials enhanced the durability and strength properties of concrete and neutralized the negative effects of waste clay brick. Utilizing only 1 percent of nano SiO2 could cover the negative effects on compressive strength of utilizing 75 percent of clay brick sand. Wasted bricks may pollute the environment and make the appearance of suburbs dirty. Therefore, utilizing such a material can be a better approach. Except, because it has no negative effect on the concrete, it can also help the construction procedure in terms of budget. The combination of nano



287

SiO2 and brick waste materials enhanced the durability and strength of concrete and also the reduction of its unit weight [28]. D. S. Klimesch et al., [29] investigated the utilization of autoclaving to treat blends of normal Portland cement with various amounts of ground brick waste. The experimental data demonstrated the feasibility of this waste to be utilized by the construction industry as a supplementary cementing material. The compressive strength achieved a maximum between 40 to 50 mass % of brick fines addition. For additions greater than 60 mass %, Altobermorite amount and its crystallinity reduced significantly. According to the researchers, the utilization of waste brick fines in combination with OPC for the production of hydrothermally cured calcium silicate based materials is a feasible option for the future [29]. In another work, Elazig region waste brick powder was used in the production of selfcompacting mortar [30]. Seven kinds of self-compacting mortar, in which cement was partially substituted by 0%, 5%, 10%, 15%, 20%, 25% and 30% of waste brick powder were manufactured. The mini slump flow and V-funnel tests were utilized to evaluate the workability of the fresh mortars whilst the water-to-powder ratios were kept constant between 0.40 and 0.42 in all samples. Eventually, it was observed that the values of the tensile strength in bending of all mortars with waste brick powder were very close to those of mortar specimens without waste brick powder at 28 and 91 days whilst the values of the early age tensile strength in bending of self-compacting mortar specimens containing waste brick powder increased compared to self-compacting mortar specimens without waste brick powder. However, the compressive strength values decreased with increasing waste brick powder content compared to self-compacting mortar specimens without waste brick powder whilst the compressive strength values of self-compacting mortar specimens with 5% and 10% waste brick powder were higher than those of self-compacting mortar specimens without waste brick powder at 3 and 7 days. Besides, the compressive strength values of self-compacting mortar specimens with 5% waste brick powder were close to those of self-compacting mortar without waste brick powder at 91 curing ages [30]. In another investigation, clay brick obtained from four European countries was ground to roughly cement fineness and utilized to partially substitute cement in quantities of 0%, 10%, 20% and 30% in standard mortars [31]. The pore volume, pore size distribution, threshold radius and strength of these mortars were experimented for curing phases of up to one year. The existence of ground brick (GB) altered the compressive strength of mortar and this was found to be attributed to both the dilution effect and production of additional C–S–H gel from the reaction of GB with CH. The additional C–S–H gel refined the pore size distribution of the mortar and this was reflected in compressive strength values acquired for these mixes [31]. R.D.T. Filho et al., [32] examined the factors that impact the Brazilian ceramic industry capacity for utilization as a partial substitute of Portland cement. Superplasticized mortars of equal workability containing ground crushed waste calcined-clay brick (GCWCCB) in


288


the proportions of 10, 20, 30 and 40% as a cement substitute were examined through mechanical tests, pore structure characterization and durability tests. The outcomes showed the optimal percentages of substitution lies between 10% to 20%. The capacity reduction of CO2 emissions could be as high as 10% of current Brazilian cement industry emissions if this approach were to be fully implemented, and it could be eligible for “Clean Development Mechanism” credits under Kyoto protocol, the authors suggested [32]. Z. Ge et al., [33], on the other hand, studied the effect of clay-brick-powder (CBP) on concrete mechanical properties, involving compressive strength, static elastic modulus, and flexural strength. The orthogonal experimental design procedure was utilized to study the serious sequence of all influencing factors, including water/cementitious material ratio, sand ratio, substitution standard and average particle size of the clay-brick-powder. A total of 17 mixes were tested involving one normal cement concrete as a reference. The mixtures with clay-brick-powder reach more than 50 MPa and 20 GPa for 28-day compressive strength and elastic modulus, respectively. The flexural strength ranged from 10 to 12 MPa. Test outcomes indicated that recycled clay-brick-powder could be utilized as partial replacement of cement in concrete. The optimal mix proportion was determined based on the experimental and orthogonal analysis [33]. The feasibility of utilizing pastes from brick waste alkali-activation for repointing existing masonries was studied [34]. Five various formulations (having SiO 2/Al2O3 molar ratio ranging from 1.4 to 0.4) and two different curing temperatures (room temperature and 50°C) were investigated. Curing at high temperature vaguely favored geopolymerization and decreased efflorescence formation. Pastes with SiO2/Al2O3 = 0.8 and 0.9 showed open porosity and water vapor permeability fairly similar to those of historic lime-based mortars, proving to be potentially compatible with them [34]. Last but not least, M. U. Rani and J. M. Jenifer [35] on their study titled “An Experimental Study on Partial Replacement of Sand with Crushed Brick in Concrete” aimed to investigate the suitability of utilizing crushed brick in concrete. Brick originated from demolished masonry was crushed in the laboratory and added partial sand substitute. Three substitute standards, 15%, 20% and 25%, were compared with the control. The tests on concrete indicated that the mechanical properties (compressive, flexural and splitting tensile strengths) of concrete containing crushed brick were well comparable to those of the concrete without ground brick [35].

5. CONCLUSION So much work has been done with the same purpose “to add value to waste brick” through value added products. Construction and building project contribute enormously to waste generation of materials with “Waste brick” being one of them. Building bricks, at the end of life span end up disposed of in landfill sites. Previous research has indicated that



289

recycled waste brick can be crushed and used for a number of different applications such as: cement replacement, heavy metal absorbents, pavement production and so on, adding value to waste to generate products which have a potential of bringing financial returns, essential for economic growth.

ACKNOWLEDGMENT The academic work presented on this chapter was based on the financial funding from the National Research Foundation (NRF) of South Africa. I would like to extent my appreciation to the University of Zululand.

REFERENCES Production of bricks from waste materials – A review. Available from: https:// www.researchgate.net/publication/257390145_Production_of_bricks_from_waste_ materials_-_A_review [accessed Oct 30 2017]. [2] https://recyclenation.com/2014/06/how-to-recycle-bricks/. [3] Environmental outlook. (2015). Waste Management, Chapter 13. Pg 277-304. https://www.environment.gov.za/sites/default/files/reports/environmentoutlook_cha pter13.pdf [Accessed Nov 09 2017]. [4] South African Statistics. (2009). Published by Statistics South Africa, Private Bag X44, Pretoria 0001, StatsSALibrary Cataloguing-in-Publication (CIP) Data, ISBN 978-0-621-38773-5. [5] Naceri, A. & Hamina, M. C. (2009). “Use of waste brick as a partial replacement of cement in mortar.” Waste Management, 29, 2378-84. [6] Poon, C. S. & Chan, D. (2006). “Paving blocks made with recycled concrete aggregate and crushed clay brick.” Construction and Building Materials, 20, 569-77. [7] Demir, I. & Orhan, M. (2003). “Reuse of waste bricks in the production line.” Building and Environment, 38, 1451-5. [8] O’Farrell, M., Wild, S. & Sabir, B. B. (2001). “Pore size distribution and compressive strength of waste clay brick mortar.” Cement & Concrete Composites, 23, 81-91. [9] Arulrajah, A., Piratheepan, J., Aatheesan, T. & Bo, M. W. M. ASCE. (2011). “Geotechnical Properties of Recycled Crushed Brick in Pavement Applications.” Journal of Materials in Civil Engineering, 23(10). [10] Arulrajah, A., Piratheepan, J., Bo, M. W. & Sivakugan, N. (2012). “Geotechnical characteristics of recycled crushed brick blends for pavement sub-base applications.” Canadian Geotechnical Journal, 49(7), 796-811. [1]


290


[11] Chen, M., Lin, J., Wu, S. & Liu, C. (2011). “Utilization of recycled brick powder as alternative filler in asphalt mixture.” Construction and Building Materials, 25(4), 1532-6. [12] Aliabdo, A. A., Abd-Elmoaty, A. E. M. & Hassan, H. H. (2014). “Utilization of crushed clay brick in cellular concrete production.” Alexandria Engineering Journal, 53(1), 119-30. [13] Lin, K. L., Wu, H. H., Shie, J. L., Hwang, C. L. & Cheng, A. (2010). “Recycling waste brick from construction and demolition of buildings as pozzolanic materials.” Waste Management and Research, 28(7), 653-9. [14] Labidi, N. S. (2008). “Removal of Mercury from Aqueous Solutions by Waste Brick.” International Journal of Environmental Research, 2(3), 275-8. [15] Demir, I., Yaprak, H. & Simsek, O. (2011). “Performance of cement mortars replaced by ground waste brick in different aggressive conditions.” Ceramics, 55(3), 268-75. [16] Zhang, S. & Zong, L. (2014). “Properties of concrete made with recycled coarse aggregate from waste brick.” Environmental Progress and Sustainable Energy, 33(4), 1283-89. [17] Zong, L., Fei, Z. & Zhang, S. (2014). “Permeability of recycled aggregate concrete containing fly ash and clay brick waste.” Journal of Cleaner Production, 70, 175-82. [18] Sharma, S., Mall, R. & Raza, K. (2014). “Effect of waste brick kiln dust with partial replacement of cement with adding superplasticizer in construction of Paver Blocks.” International Journal of Science, Engineering and Technology Research, 3(9), 22616. [19] Kinuthia, J. M. & Nidzam, R. M. (2011). “Towards zero industrial waste: Utilization of brick dust waste in sustainable construction.” Waste Management, 31(8), 1867-78. [20] Kesegic, I., Netinger, I. & Bjegovic, D. (2008). “Recycled clay brick as an aggregate for concrete: overview.” Technical Gazette, 15(3), 35-40. [21] Kooli, F., Yan, L., Al-Faze, R. & Al-Sehimi, A. (2015). “Removal enhancement of basic blue 41 by brick waste from an aqueous solution.” Arabian Journal of Chemistry, 8(3), 333-42. [22] Yahya, K. & Boussabaine, H. (2010). “Quantifying Environmental Impacts and Ecocosts from Brick Waste.” Architectural Engineering and Design Management, 6(3), 189-206. [23] Rakhimova, N. R. & Rakhimov, R. Z. (2015). “Alkali-activated cements and mortars based on blast furnace slag and red clay brick waste.” Materials & Design, 85, 32431. [24] Ge, Z., Wang, Y., Sun, R., Wu, X. & Guan, Y. (2015). “Influence of ground waste clay brick on properties of fresh and hardened concrete.” Construction and Building Materials, 98, 128-36.



291

[25] Aatheesan, T., Arulrajah, A., Bo, M. W., Vuong, B. & Wilson, J. (2010). “Crushed bricks blend with crushed rocks for pavement systems.” Waste and Resource Management, 163, 29-35. [26] Bektas, F., Wang, K. & Ceylan, H. (2009). “Effects of crushed clay brick aggregate on mortar durability.” Construction and Building Materials, 23(5), 1909-14. [27] Hussain, S., Gul, S., Khan, S., Rehman, H., Ishaq, M., Khan, A., Jan, F. K. & Din, Z. U. (2015). “Removal of Cr(VI) from aqueous solution using brick kiln chimney waste as absorbent.” Desalination and Water Treatment, 53(2), 1-9. [28] Tavakoli, D. & Heidari, A. (2014). “Properties of Concrete made with Waste Clay Brick as Sand Incorporating Nano SiO2.” Indian Journal of Science. [29] Klimesch, D. S., Gutovic, M. & Ray, A. S. (2003). “Brick waste a supplementary cementing material in autoclaved building products.” Role of Cement in Science, 28490. [30] Karatas, M., Turk, K., Acikgenc, M. & Ulucan, Z. C. (2010). “Effect of Elazig Region Waste Brick Powder on Strength and Viscosity Properties of Self Compacting Mortar.” 9th International Congress on Advances in Civil Engineering, 1-9. [31] O’Farrel, M., Wild, S. & Sabir, B. B. (2001). “Pore size distribution and compressive strength of waste clay brick mortar.” Cement and Concrete Composites, 23(1), 8191. [32] Toledo Filho, R. D., Goncalves, J. P., Americano, B. B. & Fairbaim, E. M. R. (2007). “Potential for use of crushed waste calcined-clay brick as a supplementary cementitious material in Brazil.” Cement and concrete Composites, 37(9), 1357-65. [33] Ge, Z., Gao, Z., Sun, R. & Zheng, L. (2012). “Mix design of concrete with recycled clay-brick-powder using the orthogonal design method.” Construction and Building Materials, 31, 289-93. [34] Sassoni, E., Pahlavan, P., Franzoni, E. & Bignozzi, M. C. (2016). “Valorization of brick waste by alkali-activation: A study on the possible use for masonry repointing.” Ceramics International, 42(13), 14685-94. [35] Rani, M. U. & Jenifer, J. M. (2016). “An Experimental Study on Partial Replacement of Sand with Crushed Brick in Concrete.” International Journal of Science Technology and Engineering, 2(8), 316-22.





Chapter 14

SUGARCANE BAGASSE WASTE MANAGEMENT Zimele Mzimela1, M. J. Mochane1 and Tshwafo E. Motaung1, 1

Department of Chemistry, University of Zululand, KwaDlangezwa, KwaZulu Natal, South Africa

ABSTRACT Sugarcane bagasse is the fibrous matter that remains after sugarcane has been crushed to extract its juices during the production of sugar. It represents around 30-40 wt. % of the waste materials. It is highly abundant in many countries like Brazil, South Africa, India, Peru and Australia. In 2008, South Africa alone produced 7.9 million tons of bagasse. It is estimated that 5.4 * 108 dry tons of sugarcane are processed each and every year globally. Generally, for every single ton of sugarcane, approximately 280 kg of sugarcane bagasse is generated. This material can be seen as either a waste, affecting the environment, or as a very useful resource when appropriate valorization techniques are implemented. Sugarcane bagasse is composed of, as the major components, lignin (approximately 23.5%), hemicelluloses (approximately 28.6%) and cellulose (around 48.3%), respectively. Due to its relatively low ash content (approximately 1.9%), it has the prospects of finding many applications in contrast to other agro-based residues. Basically, the chemical composition of sugarcane bagasse makes it superb for applications in the synthesis of composite materials that possess exceptional chemical and physical properties. Bagasse also has the added advantage of low fabricating costs and high quality green end materials. It has found applications in many sectors; it is converted into energy through combustion, especially in sugar industries, it is used in the production of activated carbon, in gasification, in the production of cellulosic ethanol, and in pulping, to mention but a few.

Keywords: sugarcane bagasse, waste management, composites, energy, cellulose



Corresponding Author address: Email: [email protected].


294

Zimele Mzimela, M. J. Mochane and Tshwafo E. Motaung

1. INTRODUCTION Agricultural waste, or agro-waste, includes organic wastes (such as silage effluent, animal excreta from farmyards, sludge and soil water), plant residues (which comprise of branches, wood and leaves) and finally waste such as plastics, pesticides, waste oils and scraping machinery [1]. Agro-waste management is the collection, transportation, processing, recycling or disposal, and monitoring of agricultural waste materials [1]. In many developed and developing countries, the disposal of agro-waste has become a major costly waste disposal crisis. Rice husk for example, which is a by-product of the rice milling industry, accounts for approximately 20% of the whole rice as reported by K.G Mansaray et al. [2]. The annual rice production in developing countries is approximately 500 million tons, which means that about 100 million tons of rice husk is produced [2]. The available rice husk, however, far exceeds its uses and therefore poses severe disposal issues. In many countries around the world, agro-waste management is a major concern due to technical, regulatory, financial and institutional shortcomings, to mention but a few. These shortcomings lead to severe environmental degradation, which include air pollution due to the burning of waste, soil contamination, surface and groundwater contamination via leachate, bad odor and uncontrolled release of methane by anaerobic decomposition of waste [3]. Many agro-waste management techniques have been introduced. These include composting [4], incineration [5], landfills and open dumping sites [6], and finally recycling [7]. Incineration, which can also be described as a thermal treatment, involves the combustion of agro-wastes. Typically, an incinerator processes waste materials as input materials and achieves their treatment. Another benefit of the incinerator is that, it recovers the heat energy that is released during the combustion process. Landfills are designed to hinder degradation in order to protect the environment from unfavorable contaminations. Landfills are deprived of air and water, and are more like tightly sealed storage containers. This helps in facilitating the slow and steady degradation of agro-waste materials. Landfill disposal is seen as the most cost-effective waste management option. Like the processes that occur naturally in the soil, composting helps in terms of obtaining stable products from biological oxidative transformations. If fresh waste materials are added to the soil, the result is a change in the ecosystem of the soil. Composting helps to curb this and many other disadvantages presented by adding fresh agro-waste to the soil. Another way that has been found to help in the management of agro-waste is to valorize it. One application of agro-waste that has been largely studied is its use as a potential adsorbent for water treatment [8-11]. Utilizing agro-waste for such applications is seen as


Sugarcane Bagasse Waste Management

295

a very good waste management tactic since it not only helps in the reduction of costs for waste disposal, but also contributes to environmental protection. Agro-waste has also been used in clay matrix bricks, as studied by L. Babieri et al., [12]. They studied the feasibility of utilizing agro-wastes such as sawdust and seeds (grape and cherry) as pore forming agents, and sugarcane ash as silica precursor in bricks.

2. HISTORY OF SUGARCANE Sugarcane (Figure 1) refers to several species of the tall perennial true grasses of the genus Saccharum, tribe Andropogoneae, and is used mainly for the production of sugar. It is comprised of stout, connected fibrous stalks that are rich in sucrose, which accumulates in the nodes of the stalk. It is around two to six meters tall, and it belongs to the grass family Poaceae, which also includes rice, wheat, maize, sorghum, and many other crops.

Figure 1. Sugarcane plantation.

Although different species of sugarcane are likely to have originated in different locations, sugarcane is thought to be indigenous to tropical South and Southeast Asia. Saccharun barberi originated in India, while S. Edule and S. Officinarum originated in New Guinea. The first domestication of sugarcane as a crop is theorized to have been in New Guinea around 6000 BC. Early cultivators used to chew sugarcane for its sweet juice.


296


Sugarcane was introduced to other parts of the Abbasid Caliphate (in the Mediterranean, Andalusia, Egypt, Mesopotamia and North Africa) by Muslim and Arab traders around the 8th century. China was introduced to sugarcane by India around 800 BC. By 400 BC, crude sugar was already being produced from sugarcane. Indians started commercially exploiting sugar in the sub-continent around 700 AD. As the years progressed, the culture of sugarcane started spreading westward, and by 500 AD, it had reached Persia. Prophet Mohammed initiated the next migration of sugarcane. He started a “Holy War” for the conversion of the world to Islam. His armies adopted and cultivated sugarcane after conquering Persia, and later called it the “Persian Reed.” In Egypt, sugarcane was introduced after the Egyptians were defeated by the Arabs in 710 AD. The Egyptians developed clarification, crystallization, and refining processes in order to obtain sugar from sugarcane. The spreading of sugarcane then followed its westward journey across Northern Africa, and after some time reached Morocco. It then crossed the Mediterranean to Southern Spain around 755 AD, and then to Sicily in 950 AD. In the United States of America, the harvesting of sugarcane started around 200 years ago, and the most successful sugarcane mills were developed in Louisiana. Jesuit priests were the first people to introduce sugarcane in this place in 1751. The first refined sugar from the sugarcane crop was produced by Etienne de Bore in 1795. The first years of harvesting produced approximately 300000 tons of sugar per year. In South Africa, the sugarcane industry unfolded in Natal (now known as KwaZuluNatal). Attempts were made between 1847 and 1851 to grow tropical crops within the coast of the province, especially north of Durban. Many different crops were cultivated, but sugarcane proved to be of greatest success, especially in commercial terms. By 1860, the sugarcane industry had grown massively and 23 sugar mills were in operation. About 4953 hectares of land were planted with sugarcane. Up to date, KwaZulu-Natal is the epicenter of the sugarcane industry in South Africa. Today, the harvesting of sugarcane is a very huge industry in many countries like China, Brazil, India, South Africa, Malaysia, U.S.A. and Hispaniola, which are the largest producers of sugarcane. Sugarcane is planted in furrows at horizontal or 45-degree angles (Figure 2). After it has been planted, it is covered with a layer of soil. When it begins to grow, the furrows are turned inwards and the crops mature over 9 to 24 months. The planting of seeds can be achieved by hand or by sugarcane equipment that cuts the canes into billets and plants them in furrows. Before the canes are harvested, they are exposed to fire in order to remove the leaves that cover them.



297

Figure 2. Furrows in which sugarcane is planted.

3. POLICIES ON AGRO-WASTE MANAGEMENT Economic development, an increase in population and increasing rates of urbanization in South Africa have led to an increased generation of waste which requires the establishment and implementation of effective waste management programs and policies. In accordance to schedule 5B of the South African Constitution (act 108 of 1996), the management of waste is a competence of the local government that has to be accomplished in order to protect both human and environmental health (Constitution, Section 24). The constitutional responsibility of the local government is demonstrated by the local government municipal systems act (act 32 of 2000). It is clearly understood that the generation of waste occurs either through processes where business, industrial entities or people are involved and able to take control of the outcome, or when accidents, natural processes, or disasters produce waste. The waste has to be managed in a way as to ensure a safe, healthy and sustainable environment to ensure that the rights of individuals are protected (constitution, Section 24).


298


South Africa has one of the most progressive waste management legal frameworks in the African continent. Roles, responsibilities and mandatory obligations are clearly distinguished for all the spheres of government (that is, the provincial and national governments, and the district municipalities). It is the responsibility of the waste generator to properly manage waste, and the costs of waste management should be considered part of the cost of doing business. Industrial operational and management programs should include the development of sound waste management practices for the generation, storage, handling, treatment and disposal of waste. The management of waste in South Africa relies heavily on landfills, which accounts for the majority of licensed waste facilities. It is estimated that approximately 90 percent of South Africa’s waste is disposed of at landfill sites [13]. There are, however, other alternative waste management options, which include waste recycling facilities. Table 1 shows the number of licensed waste management facilities in South Africa. Table 1. Licensed waste management facilities in South Africa [13]

The management of agricultural biomass in South Africa is still at its infancy. As a result, policies are mostly designed to revolve around the management of wastes such as municipal, organic, metals, tires, glass, plastics, papers, construction and demolition waste, as shown in chart 1.

RESEARCH AND DEVELOPMENT OF SUGARCANE BAGASSE Sugarcane bagasse constitutes a very large fraction of the waste that is obtained when sugarcane undergoes conventional milling to produce sugar. About half of this bagasse is utilized as energy for the operation of the sugar milling process. The remaining is then reserved. However, the reserved bagasse accumulates and could render major environmental concerns. This material is one of the largest agricultural residues in the world, and as a result, a lot of research has been directed towards valorizing bagasse in



299

order to curb the many environmental threats it presents and also to increase its economic value.

Chart 1. Waste composition for general waste [14].

Sugarcane bagasse is composed mainly of cellulose (which is the major component), hemicelluloses and lignin [15]. This makes it ideal for utilization as a reinforcing material in composite materials for the fabrication of materials that possess distinct physical and chemical properties. Cellulose has numerous superb properties, such as its polymeric nature, its ability to form bonds with many materials and its biodegradable nature, to mention but a few. The fact that approximately 50% of bagasse is mainly cellulose has invigorated interest in this material from different researchers. Many studies have, therefore, focused on the isolation or extraction of cellulose from sugarcane bagasse [16-18]. Cellulose extracted from sugarcane bagasse has been used in many studies as a reinforcing agent in polymer composite materials. The preparation of biodegradable nanocomposites has been achieved by casting a mixture of natural rubber and cellulose whiskers extracted from sugarcane bagasse [19]. The resulting composite was found to have improved biodegradability and thermo-mechanical properties as compared to the individual materials. The tensile strength of the composite was also enhanced. Luz et al., [20] developed a polypropylene composite reinforced with cell lignin and cellulose fibers obtained from sugarcane bagasse. Furthermore, they chemically modified the fibers by acetylating process. It was found that the mechanical properties of the composites decreased with acetylation. It was concluded, as a result, that the acetylation was not a good process for the properties of the final composite material. The addition of fibers was found to increase the flexural strength and modulus of the resulting composite material. In another


300


study, Mulinari et al., [21] obtained bagasse cellulose/HDPE composites through extrusion. They used pure cellulose and cellulose modified with zirconium oxychloride. They were able to conclude that the composites prepared from non-modified sugarcane bagasse were agglomerated. Modified cellulose presented composites with improved properties. Cellulose from sugarcane bagasse has been modified in order to increase its applicability. This is achieved by integrating different chemical functional groups on the hydroxyl groups of the glycosidic rings. For example, Viera et al., [22] were able to synthesize and characterize methylcellulose from sugarcane bagasse cellulose. This modified cellulose can find applications in such industries as food, pharmaceutical and petrochemical industries, respectively. In recent years, sugarcane bagasse ash (which is the ash that remains after sugarcane bagasse has been burnt) has been studied as a potential quartz replacement in ceramics [23-25]. This is due to the fact that the ash is composed of aluminium and silicon oxides as the major components, and iron, magnesium, potassium and calcium oxides as the minor components. Studies showed that the ash obtained from burning sugarcane bagasse has a very high concentration of quartz, and therefore has the practicality of application in ceramics and also the potential to be used in glass-based products. Another study conducted by Carrier et al., [26] focused on the potential of char from the vacuum pyrolysis of sugarcane bagasse as an activated carbon and a soil amendment. A high potential from bagasse to decolorize wastewaters and increase the soil nutrient levels and nutrient holding capacity was discovered. Sugarcane bagasse has also been utilized as a raw material for the production of ethanol through the organosolv process using dilute acid hydrolysis, which helps to increase the production yield [27]. Several other studies have focused on the production of ethanol from bagasse [28-30]. The interest in this research is motivated by the fact that the world’s demand for energy is increasing and oil reserves are progressively being depleted. Biomass such as bagasse also has the added advantage that it is renewable and it could also help to minimize greenhouse gases emitted by the use of gasoline.

CONCLUSION AND FUTURE RECOMMENDATIONS Agricultural biomass is usually burnt in farms or abandoned in a free space, resulting to a number of environmental problems. As a result, researchers have gained interest in the development of polymeric materials reinforced with fibers originated from the biomass such as pineapple leaf, sisal, jute, piassava, coir, and sugarcane bagasse. Sugarcane bagasse is one of the most abundant biomass waste materials in many tropical and semi-tropical countries. Although sugarcane bagasse fiber residues have been extensively studied and used as a source of energy, the major portion of these residues is currently burnt for energy supply in the sugar and alcohol industries. In fact, most farmers still burn it during a



301

harvesting season as a procedure to expose stalks and possibly scare away reptiles. That is uncontrolled burning, which lead to catastrophic environmental concerns. As a result, the management of agricultural wastes, particularly sugarcane bagasse has been of significant priority for governments in both global and local contexts. A number of policies have been devised in order to ensure that this waste material is handled in an appropriate manner. A lot of emphasis has also been imposed on research and development work in order to ensure that other possible applications for sugarcane bagasse are uncovered. The view of sugarcane bagasse as a probably highly applicable material is due to the significant amount of cellulose, which has gained significant interest amongst researchers due to its numerous appealing properties. In addition, more research has to be done to advance the collection (management) of sugarcane stalks as an alternative to burning.

ACKNOWLEDGMENTS The authors are grateful to the National Research Foundation of South Africa (NRF) for financial support of this project. Further appreciation goes to the University of Zululand, where this research was undertaken.

REFERENCES [1] [2] [3] [4]

Demirbas, Energy Conversion and Management, 52 (2011), 1280-1287. K. G. Mansaray, A. E. Ghaly, Energy Resources, 20 (1998), 653-663. U. N. Ngoc, H. Schnitzer, Waste Management 29 (2009), 1982-1995. M. De Bertoldi, G. Vallini, A. Pera, Waste Management and Research 1(1983), 157176. [5] D. Sud, G. Mahajan, M. P. Kaur, Bioresource Technology, 99 (2008), 6017-6027. [6] Bhatnagar, M. Sillanpaa, Chem. Eng. Journ. 157(2010), 277-296. [7] L. Barbieri, F. Andreola, I. Lancelloti, R. Taurino, Waste Management, 3(2013), 2303-2315. [8] T. Joo Hwa, S. Kuan- Yeow, Resources, Conservation and Recycling, 13(1995), 2736. [9] M. El- Fadel, A. N. Findikakis, J. O. Leckie, Journ. of Env. Management, 50(1997), 1-25. [10] K. Y. Foo, B. H. Hameed, Journal of Hazardous Materials, 172(2009), 523-531. [11] M. Dias, M. C. M. Alvim-Feral, M. F. Almeida et al. Journ. of Environ. Management, 85(2007), 833-846. [12] A. A. M. Daifullah, B. S. Girgis, H. M. H. Gad, Mat. Lett. 57(2003), 1723-1731.


302


[13] DEA (Department of Environmental Affairs), (2011). Draft Municipal Waste Sector Plan. Department of Environmental Affairs, Pretoria. [14] DEA (Department of Environmental Affairs), (2012b). National Waste Information Baseline Report. Department of Environmental Affairs, Pretoria. [15] Pandey, C. R. Soccol, P. Nigam, V. T. Soccol, Bioresource Technology, 74(2000), 69-80. [16] J. X. Sun, X. F. Sun, H. Zhao, R. C. Sun, Polymer Degradation and Stability, 84(2004), 331-339. [17] Mandal, D. Chakrabaty, Carbohydrate Polymer, 86(2011), 1291-1299. [18] E. M. Teixeira, T. J. Bondancia et al. Industrial Crops and Products, 33(2011), 6366. [19] J. Bras, M. L Hassan, C. Bruzesse, Industrial Crops and Products, 32(2010), 627633. [20] S. M. Luz, J. Del Tiro, G. J. M. Rochoa et al, Composites Part A: Applied Science and Manufacturing, 59(2008), 1362-1369. [21] D. R. Mulinari, H. J. C. Voorwald, M. O. H. Cioffi et al. Composites Science and Technology, 69(2009), 214-219. [22] R. G. B. Viera, G. R. Filho R. M. N. de Assuncao, Carbohydrate Polymers, 67(2007), 182-189. [23] S. R. Teixeira, A. E. de Souza et al. J. Am. Ceram. Soc., 91(2008), 1883-1887. [24] A. E. Souza, S. R. Tiexeira, G. T. A. Santos et al. Journal of Environmental Management, 92(2011), 2774-2780. [25] S. R. Tiexeira. R. S. Magalhaes, A. Arenales et al. Journal of Environmental Management, 134(2014), 15-19. [26] M. Carrier, A. G. Hardie, U. Uras et al. Journal of Analytical and Applied Pyrolysis, 96(2012), 24-32. [27] C. E. V. Rosell, L. D. Filho, A. G. P. Hilst, M. R. L. V. Leal, International Sugar Journal, 107(2005)192-195. [28] J. Goldenberg, S. T. Coelhr, P. Guardabassi, Energy Policy, 36(2008), 2086-2097. [29] M. O. S. Dras, A. V. Ensinas, S. A. Nebra et al. Chem. Eng. Research and Design, 87(2009), 1206-1216. [30] M. O. S. Dias, T. L. Junquera, O. Covalett, M. P. Cunha et al. Bioresource Technology, 103(2012), 152-161.




Chapter 15

POLYMER/GROUND TIRE RUBBER BLENDS AS AN ALTERNATIVE FOR WASTE TIRE MANAGEMENT Mokgaotsa J. Mochane1,*, Teboho C. Mokhena2, Luyanda L. Noto3 and Tshwafo E. Motaung1 1

Department of Chemistry, University of Zululand, KwaDlangezwa, KwaZulu Natal, South Africa 2 CSIR Materials Science and Manufacturing, Polymers and Composites, Port Elizabeth, South Africa 3 Department of Physics, University of South Africa, Florida, South Africa

ABSTRACT The increase in the number of vehicles in the world generally results in a significant problem of used tires being disposed of in landfill sites. The increase in the number of waste rubber tires becomes a serious environmental challenge. Also, the burning and landfilling of tires is strictly forbidden in the country according to South African regulations. In other countries in the world, the waste tires have been used as fuel in cement kilns. However, this is not economically feasible since tires release greenhouse gases, leading to global warming and climate change. Different alternatives have been suggested to recycle tire rubber to add value to it through value added products but the large scale usage of these methods remain unfeasible due to high cost involved in implementation stages. One of the most promising emerging waste management approaches is the mechanical recycling of tires. The mechanical recycling of tires involves the grinding of tires as well as splitting the metal and rubber components. The grinding of tires, followed by the addition of ground tire rubber to polymer matrices seems to be the most viable method of doing much more value addition to waste tire to generate products which can bring financial returns. This approach also assist South African government to establish a *

Corresponding author: Email: [email protected].


304

Mokgaotsa J. Mochane, Tebogo C. Mokhena, Luyanda L. Noto et al. proper waste management strategy and support the Department of Science and Technology’s Bio-economy strategy.

Keywords: ground tire rubber, greenhouse gases, landfill sites, waste management, polymer matrix

1. INTRODUCTION For the past decades, the disposal of worn tires and their economical recycling represent a huge challenge for both academic and industrial sectors [1]. It is reported that about 800 million tires are discarded around the world with the figure estimated to increase by 2% yearly [2]. Methods such as landfilling and tire mono filling were amongst the most favoured ways of tire disposal around the globe. Landfilling is one of the most dangerous methods of disposing tires since it causes serious environmental problems without future economic benefits. One of the important characteristics of tire rubber is that they are impermeable, which causes them to hold water for a longer period of time, as a result, becomes sites for mosquito breeding. It is well known that mosquito breeding causes deadly diseases such as dengue and malaria. Furthermore, waste tires also present environmental homes for dangerous animals such as snakes [3]. In addition, tires have poor flammability properties, therefore, the discarded tires pose a serious fire threat as it is not easily extinguished. Different methods were used for waste tires management approaches. One of the cheapest and common methods of waste tire management is mechanical recycling. The mechanical recycling is the grinding of tires and separation of metal and rubber components. It was shown that the recycling of ground tire rubber (GTR) powders as active fillers in host polymers is an alternative method for waste tire management [4]. In this chapter the use of ground tire rubber (GTR)/polymer blends as an alternative for waste tire management is discussed.

2. PRODUCTION OF RUBBER/TIRES It is well known that each material whether we are talking about an iPhone or a battery, even the most complex technological device is made up of the raw materials, the same is true for tires. Natural rubber is mostly acquired from the latex of the Hevea brasiliensis tree [5]. The Hevea brasiliensis tree (Figure 1) is naturally occurring in the South America, more specifically in the Amazon valley. The species is also found in countries such as Southeast Asia, Malaysia and Indonesia. Currently, it has been discovered that regions between 5 to 10°C latitude north or south of the equator have a huge possibility to grow rubber trees. The Hevea brasiliensis tree is no longer cultivated in the original birth place


Polymer/Ground Tire Rubber Blends as an Alternative for Waste Tire Management 305 (South America) because of the leaf blight disease. Current investigations are done in order to control the disease. However, as much as the disease is trying to pose threat to the main tree, two types of Hevea species known as Heveabenthaniama and Hevea pauciflora are resistant to leaf blight. Generally, natural rubber is occurring in more than 100 different species of plants, however all of them have low yield, purity, and longevity compared Hevea.

3. HISTORY OF TIRES A tire or tire is a ring-shaped vehicle component that covers the wheel’s rim to protect it and enable better vehicle performance. The earliest tires were bands of leather, followed by iron and later steel were placed on wooden wheels used on carts and wagons. During the 18th century, rubber was not utilized in most parts of the world including Europe except for manufacturing elastic bands and pencil. The first person to name an eraser a “rubber” was Joseph Priestley a founder of modern study of Chemistry [6]. Besides pencil erasers, rubber was used for many other products; however, the products were not able to withstand extreme temperatures, becoming brittle in winter. Charles Goodyear investigated the making of rubber more resistant to various chemicals. The study included mixing a rubber with a couple of dry powders, with the aim of making a rubber stickier. The resultant product was discovered to withstand 132oC for more than 5 hours with the application of steam heat under pressure. Since vulcanization was discovered, manufactures globally, started the production of tires from solid rubber with the resultant material being able to resist cuts and abrasions. It became apparent that tires were generally heavy as well as rigid. The so called pneumatic rubbers which composed of rubber and filled with air came into the picture by Robert Thomson. The idea was further commercialized by John Dunlop with the discovery getting the public attention since this lighter tire provided better ride. John Dunlop’s idea was the development of pneumatic tires for bicycles [5]. With the arrival of automobile, the rubber industry was born and became popular.

Figure 1. A typical Hevea brasiliensis tree.


306

Mokgaotsa J. Mochane, Tebogo C. Mokhena, Luyanda L. Noto et al.

4. COMPOSITION OF TIRES AND THEIR FUNCTIONS It is well known that each product has different individual elements with specific properties and composition to achieve the final product, the same is true for tires. The main elements of tires are shown in Figure 2. A tire composes of (i) liner, which is defined as the inner coating of synthetic rubber; (ii) plies which are layers made from different materials added together (iii) bead heel, which are known as steel, composed of wires conforming a ring surrounded by a hard rubber layer (iv) side wall, which is a mixture consisting of both natural and synthetic rubber with small content of carbon and other additives (v) lastly, tread, which is found to be a synthetic and natural rubber, which is in direct contact with the ground for the purpose of abrasion and traction resistant according to Hita and co-workers [7]. All materials (including tires) compositions seem to vary significantly due to different applications. The materials of tires are carbon black; steel; natural rubber; synthetic rubber; butadiene rubber and styrene-butadiene rubber. Carbon black is used for reinforcing rubber and for increasing tire resistance towards abrasion and fracture. Table 1 shows a typical example of basic material composition in USA and European Union according to Hita and colleagues [7]. The Table shows a typical composition of passenger car tire (PCT) and truck tire (TT).

Figure 2. Transversal cut of a radial tire [7].

Table 1. Typical materials used in tire manufacturing [7] Material’s percentage (wt.%) Synthetic rubber Carbon black Steel Natural rubber Othersa a Nylon, fillers, accelerators and sulphur

PCT USA 27 28 14-15 14 16-17

PCT EU 23 28 13 22 14

TT USA 14 28 14-15 27 16-17

TT EU 15 20 25 30 10


Polymer/Ground Tire Rubber Blends as an Alternative for Waste Tire Management 307

5. GOVERNMENT REGULATIONS IN WASTE TIRE MANAGEMENT (GLOBALLY) 5.1. Tire Waste Regulations in United States and European Union It is key for the government to play a huge role for the development of sustainable waste tire management. Generally, in the United States (US), the legislations require tires to be cut, sliced or shredded before landfilling. It was mentioned earlier in this document that tires have become environmental homes for dangerous species such as snakes. In order to minimize tyre waste disposal in landfill sites, regulations are designed such that they support extensive labour through tire size reduction by cutting. Not only this, disposal costs remain strictly high to avoid massive waste tire disposal to landfill sites. European Union adopted three different legislations with regard to waste tire management. The first is known as the directive on landfill of the waste tire, it was adopted in the year 1999. Secondly, it was of significant importance that the End of Life Vehicle Directive 2000/53/EC, which was passed in year 2000, states that the removal of the tires from vehicle before demolition should ensure that the tires are recycled rather than disposal. Thirdly, the legislation is based on an incineration of waste, aiming at reducing dioxins emissions to an approximation of 80% to 90% by the year 2005, which is advantageous in the use tires for energy recovery and recycling of the material [8].

5.2. Waste Tire Management Regulations in South Africa The Waste Tyre Regulations of 2009 which were promulgated (GG No. 31901 vol. 524) on the 13th of February 2009 came into effect on the 30th of June 2009 in South Africa. As it is the case with most regulations, the aim of this regulation is to regulate the management of waste tyres by providing for the regulatory mechanisms. The regulation was applied uniformly in all provinces in South Africa. The regulations affect waste tyre producers, waste tyre dealers, waste tyre stockpile owners, landfill site owners and tyre recyclers. In short, the regulations contain the following requirements: Section 4 of the regulations requires that no person may, (a) manage waste tyres in a manner which does not comply with the regulations, (b) recycle, recover or dispose of a waste tyre, at any facility or on any site, unless the recycling, recovery or disposal of that waste tyre is authorised by law, (c) recover or dispose of a waste tyre in a manner that is likely to cause pollution of the environment or harm to human health and well-being, or (d) dispose of waste tyres at a disposal facility two years from the date of commencement of the regulations unless such a waste tyre has been cut into quarters and no quartered waste tyres may be disposed five years from the date of promulgation of these regulations unless such


308


waste tyres have been shredded, excluding in both instances bicycle tyres and tyres with an outside diameter above 1400 mm and tyres used as engineering material. Tyre producers and waste tyre stockpile owners must register with the Minister of Water and Environmental Affairs within 30 days of the date of commencement of the regulations and tyre dealers commencing after the regulations must register with the Minister at least 30 days prior to commencing the business. Tyre producers are required to prepare and submit to the Minister an integrated industry waste tyre management plan within 60 days of registering, for approval. Alternatively, tyre producers must register with an existing integrated industry waste tyre management plan approved by the Minister and comply with such plans. The contents of an integrated industry waste tyre management plan must include amongst others, annual projections of the quantities of tyres that are manufactured or imported that will become waste tyres; identify potential number of waste storage sites; indicate how information on waste tyres collected and treated will be recorded; how national awareness regarding management of waste tyres will be raised and issues of social responsibility in the industry; auditing and reporting; measures to be implemented to give effect to best environmental practice as well as job creation, training and development. In conclusion, the regulations stipulate that all waste tyre storage sites in excess of 500 m2 are required to obtain a waste management license in terms of the National Environmental Management Waste Act, 2008 [9]. Despite the regulations, the tire waste is still increasing yearly not only in South Africa but globally.

6. DIFFERENT METHODS OF WASTE TIRE RECOVERY It is interesting to note that as much as we regard used tyres as waste, they could also be regarded as rich material because of the sources of valuable raw materials present in them. Generally, waste tyres are produced from replacement of reused tyres with the new ones. Several methods have been investigated to utilize end of life tire by reclaiming, devulcanization, high pressure and high temperature sintering, energy recovery, and pyrolysis. Figure 3 illustrates the kind of trend that is expected globally in terms of waste tire management.

6.1. Recycling The recycling of waste tires may be explained in two ways (i) using the waste tires as a whole or mechanically modified shapes viz. in crumps or shredded (Figure 4) and (ii) separation of waste tire contents into different materials. The recycling or mechanical modification allows the direct use of tires without any major investments. The whole waste


Polymer/Ground Tire Rubber Blends as an Alternative for Waste Tire Management 309 tire is applied in applications such as artificial reef, playground equipment (Figure 5), erosion control and breakwaters. Waste tires are shredded into crumbs explained elsewhere in this document and are mostly used in rubber or plastic industries to form products such as mats and athletic tracks. The recycled tire carbon black has been applied for the recovery of Battery Anode (Figure 4).

Figure 3. Shows the trend which is expected all over the world.

Figure 4. Recycled tire carbon black recovery for anode battery.


310


Figure 5. Typical example of playing ground equipment.

6.2. Pyrolysis Pyrolysis is the process whereby the rubber component is decomposed in nonoxidation behaviour in the presence of heat. The product is the main component used to make tire such as carbon black, sulphur oils and gases as it is seen in Figure 6. Pyrolysis is somehow considered one of the most favourable methods for a possible waste tire management strategy [10-11]. The advantages of pyrolysis are underlined in Table 2. This is a very versatile process which allows the addition of tires with other wastes materials such as plastics, coal or biomasses, which happens to have higher energetic efficiency [1, 12]. Environmentally, it is a safe method to be employed than the so called incineration. The main reason for this is that pyrolysis is able to minimize the release of gases such as CO2, NOx, and SOx. It is noted that pyrolysis is able to be changed in size or scale, as a result it can be implemented successfully in already existing refineries to improve the systems generally so that gaseous and liquid products can be processed together. This emerges pyrolysis as a primary treatment which provides efficiency for upgrading each product fraction separately as a result, enhancing the profitability of refinery units. Table 2. Advantages of the pyrolysis process for waste tire [10] Operational Treatment together with other wastes Energetic integration Product versatility

Environmental Valorisation of potentially hazardous wastes Minimized emissions

Economical Integrated into depreciated refineries Energetic efficiency



Figure 6. Summary of the Pyrolysis products from waste tires.

6.2.1. Tire Pyrolysis Oil The tire pyrolysis oil is characterized as dark brown/black coloured medium viscosity oil with an aromatic odour. Chemically, the oil is very complex since it consists of more than 100 identified compounds [11]. Fractionation of the oil has shown that the oil composes of aliphatic, aromatic, heteroatom and polar fractionations. According to the study [13], oil composition from the pyrolysis of tyre consists of 27 wt.% alkanes, 42 wt.% aromatics, 27 wt.% non-hydrocarbons and 4 wt.% as asphalt. However, different compositions were obtained by Conesa and co-workers. The authors reported 39.5 wt.% of aliphatic fraction, 19.1 wt.% aromatic portion, 21.3 wt.% hetero-atom and 20.1 wt.% polar fraction. 6.2.2. Char Production from Pyrolysis The composition of char produced from the pyrolysis process ranges from 20-50 wt.%. It is well known that most chars have higher content of carbon. In case of pyrolysis, the carbon content is as high as 90 wt.% and sulphur content was reported to be around 1.9 to 2.7 wt.% [11]. The processing conditions were observed to influence the nature of the char formed. Pyrolysis as mentioned earlier is the process whereby the rubber component is


312


decomposed in the presence of heat. As a result, temperature is one of the processing parameter which has a huge influence on the formation of the char produced. Char characteristics in relation to pyrolysis temperature over the range of 450-600°C was investigated elsewhere in the literature [13]. It was reported by the authors that surface area and mesopore volume increased with an increase in the temperature of the pyrolysis, whereas the volatile and hydrogen content of the char product decreased. According to the authors this was due to the loss of molecular weight of hydrocarbons which resulted in widening of the pore and increase in surface area. Similar behaviour was observed by a number of researchers [14-15] whereby the volatile content of the product decreased with increasing temperature.

6.2.3. Gas Production from Pyrolysis of Waste Tires The main gases produced from pyrolysis of waste tires include: methane, ethane, propane, butane, carbon dioxide, carbon monoxide as well as hydrogen sulphide. The influence of pyrolysis temperature on the production gases seems to be different to the char characteristics. The overall gas production is reported to increase with the increase in the pyrolysis temperature [16, 17]. This was attributed to the thermal cracking of the pyrolysis oil vapours at higher temperatures resulting in higher gas yields.

6.3. Energy Recovery It is well known that a tire contains more than 95% of organic materials with a heat value in the range 32.6 MJ/kg in comparison to the coal with a heat value of 18.6 to 27.9 MJ/kg. It is important for most of these materials to be applied in higher temperature applications. The whole and/or shredded tire are employed as fuel source in cement kilns which normally operates at higher temperatures above 1200°C, which result in a complete combustion tires’ components. The resultant ash and steel cord is attached to the clinker and the product is environmentally safe because of much lower emission compared to coal combustion. In cement kilns as one of the applications of waste tires as explained above, when tires are burned in cement production, the production rates may increase in the preheated kilns. The phenomenon is made possible as the preheated calcination rate increased in the preheater compared to the calcination of normal coal. However, as much as there are some advantages from burning of waste tires, there are also some environmental concerns in relation to burning of tires. Generally, tires include up to 17 heavy metals such as lead, chromium, cadmium, and mercury. Apparently, synthetic rubber often contains organic chemicals such as styrene and butadiene. It is well known that styrene is a benzene derivative and it is suspected of a human carcinogen, while butadiene is well known to cause the same illness.



6.4. Part Worn Tires The kind of tires that are still capable of being used in our roads are called part worn tires. As it is shown in Figure 3, they can be distinguished into two groups (i) reusable and (ii) retreadable tires. The reusable tires have an advantage of having a huge amount of tire tread remaining in the tire as a result they can still be reused on the road. Retreadable tires are waste tires with application of new treads. According to the literature [8], a tire may be retreaded twice a year depending on how well the tire was taken care off.

7. SUMMARY ON TIRE UTILIZATION Generally, it is important that the waste tire production should be prevented or minimized based on all concerns mentioned in this chapter. Figure 7 shows the best possible method for waste tire utilization. Consumers should be encouraged to drive in a good behaviour as well as taking good care of the tire in order to increase the tire life on the road. This process will definitely ensure proper use of tires as a result, delay waste tire generation since complete prevention of tires at this stage seems impossible. A tire in good condition could basically undergo the process of retreading which would be a huge boost for retreading industry [18-19]. A retreaded tire would minimize the production of a new tire, thereby reducing the amount of waste generation and energy as well as conservation of resources. The most frequently used methods for waste tire utilization is recycling followed by recovery [20, 21].

Figure 7. Summary of waste tire utilization.


314


8. RECENT RESEARCH AND DEVELOPMENT OF WASTE TIRE MANAGEMENT It is well known that polymers are everywhere and play an important role in our everyday lives. As such, we are heavily dependent on polymeric products. Blending waste tire rubber with polymers will officially allow for the reduction cost of the products produced. The addition of waste tire rubber into polymeric matrices supports the re-using of the tire rubber as a result serves as one option to recycle the waste tires [8].

8.1. Shredded and Pulverized Waste Tires In order for waste tire rubber (Figure 8a) to be added into polymer matrices, it has to be shredded or pulverized into smaller particles (Figure 8b) and the product (shredded tire) is called ground rubber tire (GRT). To convert the whole tire into ground rubber tire (GRT), the following steps are necessary: (i) shredding or pulverizing (ii) separation (steel, textile), (iii) granulation and (iv) classification. Grinders are one of the most diverse sets of milling equipment. They are often used to reduce large aggregates to a powder. Grinding mills can supply a load to a material by impaction, attrition, or compression. It has been mentioned elsewhere that GRT can be produced by mechanical grinding at ambient temperature under wet conditions, higher temperature and low temperature as tabulated in Table 3 [22]. Before grinding a tire into smaller particle size, the tire is cut into large size and then shredded into smaller particle. According to the literature [22], the particle size and particle size distribution of GRT depend on the milling sequences and mill type. For example, the use of finishing mills method can give a mean particle size of approximately 200 µm. Table 3 summarizes some of the methods used for waste tire shredding or downsizing. The stirred media milling has become a widely used processing technique for the production of micron- and nano-sized particles. The wet grinding method is cooled by water spraying. After the whole process, there is separation of water from the GTR and the product is dried. The high temperature grinding method is the one in which uses the temperature approximately 130°C, which is accompanied by substantial devulcanization. This method is rarely used because of a high particle size resulting from the process. This behavior is attributed to the viscoelastic nature of rubber, accompanied with its low heat conductivity. In order to lower the rising temperature of the rubber during grinding, water may be added into the system.



Figure 8. Typical pictures of (a) whole tire (b) ground rubber tire.

Table 3. Summarized methods for pulverization of waste tires [22, 23] Methods Ambient

Description Grinding, shredder, mills,

Advantages Better surface area

Wet ambient

(i) Grinding suspension of shredded rubber by the use grindstone (ii)Water is employed in this method to cool granulates and grindstone (i) Employed for large size tires e.g., tractors (ii)Water jar with pressure higher than 2000 bar and high velocity for stripping rubber Rubber cooled in liquid nitrogen shattered using impact type mill

(i)As the first method, high surface area and volume are obtained (ii) small degradation level on granulate Environmentally safe, energy saving

Water jet

Cryogenic

Resultant granulates are much more cleaner

Disadvantages (i)Temperature may rise to 130°C (ii) Oxidation could occur on the surface of granulates Drying step and shredding of tires are need before the grinding process

Requires high pressure and it is financial costly since it requires an expect or a trained personnel High cost of liquid nitrogen is one of the setbacks

8.2. Ground Rubber Tire in Polymer Blends One of way of recycling waste tire as mentioned in Section 8.1 is the incorporation of ground rubber tire (GRT) into polymers to form blends. This is due to a big market share of polymers compared to any material. Polymers are distinguished into 3 groups, namely (i) thermosets, (ii) thermoplastic and (iii) rubber. Amongst the 3 polymer groups, the use of GTR in thermoplastics was often preferred than in rubber and thermosets. This was encouraged by the following aspects:


Table 4. Summary of selected studies on the GTR/commodity thermoplastics blends

Size

Blend ratio (Polymer/GTR)

Compatibilization method

PP

Type (grinding method) Wet ambient

50 mesh

100/0…50/50

Chemical foaming

PP

Wet ambient

0.03-0.05mm

PP/PP-gMA/EPDM/GTR(different composition)

PP-g-MA and EPDM

LDPE

Ambient

0.08-1mm

100/0………55/45

EVA (0 to 20 wt.%)

0-05 mm

50/50

Gamma irradiation

025-0.5 mm

30/70

EVA (0 to 30 wt.%) EB irradiation

0.3 mm 0.15 mm

LDPE/GTR:3/2

EGMA, EAA, EVA, SEBS-gMA, SEBS

Thermoplastic polymer

Recycled HDPE

Recycled LDPE/LDPE

Ambient

LLDPE

Cryogenic

Results

References

The increase in GTR was inversely proportional to the foam cell size Fairly good properties provided that PP-g-MA and EPDM content is higher Mechanical properties decreased with the addition of GTR content Irradiation leads to improvement in mechanical properties compared to uncompatibilized blends Mechanical properties improved in the presence of irradiation as it was the case in the previous study Impact energy decrease in the presence of GTR, however compatibilizers counteract this behavior

[26]


[27]

[28]

[4]

[29]

[30]

Polymer/Ground Tire Rubber Blends as an Alternative for Waste Tire Management 317 1. Incorporating a mere 10 wt.% of GTR in thermoplastic is regarded as a big consumption of waste tire [22]. One can imagine that the blend ratio of 50/50 polymer/GTR would results in a huge consumption of the waste tire. 2. In some cases, thermoplastic may act as a binder allowing the employment of GTR as a major component in the blend. 3. The cost may be reduced further by using recycled thermoplastics which are available in the market in abundance. The recycled thermoplastics can be modified by using GTR. The research and development of the GTR with some commodity plastics is summarized in Table 4. It should be emphasized that the Table includes selected research and development studies on GRT/thermoplastic as there is a lot that has been investigated in relation to the topic. According to Table 4, mechanical properties of the blends decrease with the addition of GTR. Hence it is important to perform surface treatment of the GTR or use compatibilizers. Table 4 also suggests that attempts were also made to blend GTR with recycled thermoplastic polymers. The authors in the study [24] investigated recycled LDPE and GTR with pure EVA as well LDPE as supplement matrix. Interesting enough, the content of the recycled materials was 70 wt.% (total utilization) in the system i.e., 40 and 30 wt.% respectively for rLDPE as well GTR. The blend was irradiated using electron beam. The authors observed an increase in mechanical properties in the presence of EVA. Elsewhere [25] in the literature the researchers have investigated recycled HDPE (rHDPE)/GTR blend, which was subjected to peroxide crosslinking to improve the interfacial adhesion. The authors observed an improvement of the mechanical properties of rHDPE/GTR blend using gamma radiation. So far, the research and development focused on the processability and mechanical properties of thermoplastic/GTR blend which is good for the reduction of waste tire consumption. However, one might be concerned about how well can the R&D support the market penetration and also to find the novel application fields that GTR badly requires.

CONCLUSION Tires consists of many components that possess a lot of properties. They are made up of many materials to form a complex engineering structure, suitable for a wide range of environmental conditions. It is well known that a rubber is the major component used to make up a tire. A yearly increase of waste tires has been observed and scientists and engineers are now developing innovative strategies to do much more value addition to waste tires through value added products in order to generate wealth. As explained in this chapter, a tire rubber has to be shredded and granulated into a powder or smaller particles in order for the rubber component to be recycled. Ground rubber is recycled by incorporating it into polymer matrices, more especially thermoplastic due to thermoplastic


318


industry’s interest in making thermoplastic elastomers. Furthermore, the incorporation of as little as 10 wt.% GTR into polymers may results in a huge consumption of waste tires. So far many arguments in this chapter support the recycling of waste tires through the production of ground rubber tire. A huge challenge is to find specific novel applications for ground tire rubber/polymer composites. But the addition of GTR into thermoplastics is a little bit disappointing, unless waste materials such as discarded transportation crates are used as polymer matrix. Future interest should be based on incorporating GRT into thermosets such as polyurethane (PU). Because PU could be seen as a binder for GRT in construction as well as civil engineering applications. The production of gases such as hydrogen from the pyrolysis process is of interest as it helps in the predicted bright hydrogen economy for future purposes.

REFERENCES [1]

[2]

[3]

[4]

[5] [6]

[7]

[8]

Sharma, V. K., Fortuna, F., Mincarini, M., Berillo, M. & Cornacchia, G. (2000).Disposal of waste tyres for energy recovery and safe environment. Applied Energy, 65, 381-394. https://doi.org/10.1016/S0306-2619(99)00085-9. van Beukering, P. J. H. & Janssen, M. A. (2001). Trade and recycling of used tyres in Western and Eastern Europe. Resources, Conservation and Recycling, 33, 235265. https://doi.org/10.1016/S0921-3449(01)00082-9. Adhikari, B., De, D. & Maiti, S. (2000). Reclamation and recycling of waste rubber. Progress in Polymer Science, 25, 909-948. https://doi.org/10.1016/S00796700(00)00020-4. Sonnier, R., Leroy, E., Clerc, L., Bergeret, A. & Lopez-Cuesta, J. M. (2006). Compatibilization of polyethylene/ground tyre rubber blends by γ irradiation. Polymer Degradation and Stability, 91, 2375-2379. https://doi.org/10.1016/ j.polymdegradstab.2006.04.001. Semegen, S. T. (2003). Rubber, Natural. Encyclopedia of Physical Science and Technology (Third Edition), 381–394. Rosenboom, O. A. & Kowalsky, M. J. (2004). Reversed in plane cyclic behaviour of post-tensioned clay brick masonry walls. Journal of Structural Engineering, 130(5), 787-798. http://dx.doi.org/10.1061/(ASCE)0733-9445(2004)130:5(787). Hita, I., Arabiourrutia, M., Olazar M., Bilbao, J., Arandes, M.& Castaño, P. (2016). Opportunities and barriers for producing high quality fuels from the pyrolysis of scrap tires. Renewable and Sustainable Energy Reviews, 56, 745759.https://doi.org/10.1016/j.rser.2015.11.081. Ramarad, S., Khalid, M., Ratnam, C.T., Chuah, A.L. & Rashmi, W. (2015). Waste tire rubber in polymer blends: A review on the evolution, properties and future. Progress in Materials Science, 72, 100-140.https://doi.org/10.1016/ j.pmatsci.2015.02.004.


Polymer/Ground Tire Rubber Blends as an Alternative for Waste Tire Management 319 [9] Government of South Africa report on waste tyre regulations, 2009, 27 July 2009. [10] Lombardi, L., Carnevale, E. & Corti, A. (2015). A review of technologies and performances of thermal treatment systems for energy recovery from waste. Waste Management, 17, 26-44.https://doi.org/10.1016/j.wasman.2014.11.010. [11] Williams, P. T. (2013). Pyrolysis of waste tyres: A review. Waste Management, 33, 1714-1728.https://doi.org/10.1016/j.wasman.2013.05.003. [12] Larma, S. S., Liew, R. K., Jusoh, A., Chong, C. T., Ani, F. N. & Chase, H. A. (2016).Progress in waste oil to sustainable energy, with emphasis on pyrolysis techniques. Renew Sustain Energy Rev, 53, 741-753.https://doi.org/10.1016 /j.rser.2015.09.005. [13] Cunliffe, A. M. & Williams, P. T. (1999). Influence of process conditions on the rate of activation of chars derived from pyrolysis of used tires. Energy and Fuels,13, 166175.Doi:10.1021/ef9801524 CCC: $18.00. [14] Li, S. Q, Yao, Q., Chi, Y., Yan, J. H. & Cen, K. F. (2004). Pilot-scale pyrolysis of scrap tires in a continuous rotary kiln reactor. Industrial Engineering Chemistry Research, 43, 5133-5145.doi: 10.1021/ie030115m. [15] Galvagno, S., Casu, S., Casabianca, T., Calabrese, A. & Cornacchia, G. (2002). Pyrolysis process for the treatment of scrap tyres: preliminary experimental results. Waste Management, 22, 917-923.https://doi.org/10.1016/S0956-053X(02)00083-1. [16] Kaminsky, W., Mennerich, C. & Zhang, Z. (2009). Feedstock recycling of synthetic and natural rubber by pyrolysis in a fluidized bed. Journal of Analytical and Applied Pyrolysis, 85, 334-337.https://doi.org/10.1016/j.jaap.2008.11.012. [17] Williams, P. T. & Brindle, A.J. (2003). Fluidised bed pyrolysis and catalytic pyrolysis of scrap tyres. Environmental Technology, 24, 921929.http://dx.doi.org/10.1080/09593330309385629. [18] Ferrer, G. (1997). The economics of tire remanufacturing. Resources, Conservation and Recycling, 19, 221-255.https://doi.org/10.1016/S0921-3449(96)01181-0. [19] Purcell, A. H. (1978). Tire recycling: research trends and needs. Conservation & Recycling, 2, 137-143.https://doi.org/10.1016/0361-3658(78)90053-X. [20] Fukumori, K., Matsushita, M., Okamoto, H., Sato, N., Suzuki, Y. & Takeuchi, K. (2002). Recycling technology of tire rubber. JSAE Review, 23, 259264.https://doi.org/10.1016/S0389-4304(02)00173-X. [21] Ferrào, P., Ribeiro, P. & Silva, P. (2008). A management system for end-of-life tyres: a Portuguese case study. Waste Management, 28, 604-614.https://doi.org/ 10.1016/j.wasman.2007.02.033. [22] Karger-Kocsis, J., Mészáros, L. & Bárány, T. (2013). Ground tyre rubber (GTR) in thermoplastics, thermosets and rubbers. Journal of Materials Science, 48, 1-38. doi:10.1007/s10853-012-6564-2.


320


[23] Sienkiewicz, M., Kucinska-Lipka, J., Janik, H. & Balas, A. (2012). Progress in used tyres management in the European Union: a review. Waste Management, 32, 17421751.https://doi.org/10.1016/j.wasman.2012.05.010. [24] Mèszáros, L., Bárány, T. & Csvikovszky, T. (2012). EB-promoted recycling of waste tire rubber with polyolefins. Radiantion Physics and Chemistry, 81, 13571360.https://doi.org/10.1016/j.radphyschem.2011.11.058. [25] Sonnier, R., Leroy, E., Clerc, L., Bergeret, A., Lopez-Cuesta, J. M. & Bretelle, A.S. (2008). Compatibilizing thermoplastic/ground tyre rubber powder blends. Efficiency and limits. Polymer Testing, 27, 901-907. https://doi.org/10.1016/ j.polymertesting.2008.07.003. [26] Xin, Z. X., Zhang, Z.X., Pal, K., Kang, D. J., Lee, S. H. & Kim, J. K. (2009). Vinyl Addit Technol, 15(4), 275.doi:10.1002/vnl.20198. [27] Balasubramanian, M., Paglicawan, M. A., Zhang, Z. X., Lee, S. H., Xin, Z. X. & Kim, J. K. (2008). Journal of Thermoplastic Composite Materials, 21(1), 51.doi:10.1177/0892705707084543. [28] Mèszáros, L., Tábi, T., Kovács, J. G. & Bárány, T. (2008). Polymer Engineering and Science, 48 (5), 868. [29] Mèszáros, L., Fejős, M. & Bárány, T. (2012). Mechanical properties of recycled LDPE/EVA/ground tyre rubber blends: Effects of EVA content and post irradiation. Journal of Applied Polymer Science,125(1), 512.doi:10.1002/app.35675. [30] Rajalingam, P. & Baker, W. E. (1992). The role of functional polymers in ground rubber tire-polyethylene composite. Rubber Chemistry Technology,65(5), 908916.doi: http://dx.doi.org/10.5254/1.3538650.


ABOUT THE EDITOR Linda Zikhona Linganiso Senior Lecturer, University of Zululand KwaDlangezwa, KwaZulu Natal Province South Africa [email protected] [email protected]



INDEX

A Abaca fibres, 147 absorption capacity, 46 accessibility, 112, 132, 142 acetic acid, 110, 144, 256, 257 Acetogenesis, 256 acetone, 143, 144, 234 acetylation, 144, 169, 299 Acetylation treatment, 143 acid, 80, 95, 109, 110, 111, 112, 114, 115, 117, 118, 120, 121, 127, 130, 132, 143, 146, 157, 173, 207, 213, 228, 231, 232, 233, 234, 235, 236, 237, 238, 243, 247, 255, 256, 258, 266, 282, 284, 300 acid hydrolysis, 110, 114, 115, 118, 146, 157, 232, 233, 234, 235, 300 acidic, 192, 201, 232, 243, 256, 286 acidity, 211, 256, 257 Acidogenesis, 255 acoustic insulation, 30 acrylic acid, 145, 246 actinomycetes, 90, 214 activated carbon, xiii, 286, 293, 300 activation energy, 51, 52, 53, 286 adhesion, 123, 144, 145, 152, 169, 238, 239, 240, 241, 247 adhesion properties, 238 aerated concrete, 281 aerobic bacteria, 90 aerobic biodegradation, 215, 216 aerospace, 124, 133, 137

Africa, vii, viii, x, xiii, 1, 2, 3, 7, 8, 11, 12, 16, 17, 39, 56, 57, 61, 68, 83, 94, 104, 107, 109, 125, 160, 163, 258, 259, 260, 289, 293, 296, 298, 303, 307 Agricultural Biomass, 252 agricultural residues, xi, 15, 203, 298 agricultural sector, 84, 258, 260, 261 Agricultural waste, 84, 125, 183, 294 agriculture, 62, 190, 230, 258, 259, 260, 261 agro-waste management, 294 air pollution, 73, 108, 193, 294 algae, 204, 212, 235 aliphatic compounds, 171 aliphatic polyester, 213 alkali silicate, 185 Alkali treatment, 111, 133, 143 alkaline hydrolysis, 111 alkaline treatment, 111, 129, 228 aluminosilicates, 185 ammonia, 256, 264, 266, 273 anaerobic biodegradation, 215, 216 anaerobic digesters, 13, 15, 253 anaerobic digestion, 11, 94, 118, 130, 216, 251, 252, 253, 254, 255, 256, 257, 258, 262, 263, 264, 265, 266, 268, 271, 272, 273, 274 anaerobic digestion test, 216 anaerobic sludge test, 216 Analytical Techniques, 215 Andy, 139 Anhydride treatment, 144 anode, 96, 97, 98, 102, 309 antibiotic, xii, 227


324

Index

applications, ix, x, xii, xiii, 14, 15, 27, 28, 31, 34, 36, 37, 39, 43, 44, 47, 48, 53, 62, 63, 69, 73, 75, 81, 83, 87, 90, 94, 95, 96, 107, 108, 109, 113, 117, 121, 122, 124, 126, 135, 136, 137, 140, 147, 149, 153, 168, 189, 192, 199, 200, 201, 204, 218, 221, 224, 227, 229, 231, 234, 235, 237, 238, 240, 241, 242, 245, 247, 248, 275, 276, 281, 289, 293, 294, 300, 301, 306, 309, 312, 318 Applications of Graphene, 94 aqueous solutions, 282, 284 aromatics, 112, 311 arthropods, 228, 231 artificial pozzolan, 279 asbestos, 23, 190 asbestos-cement, 190 Asia, 74, 124, 139, 155, 160, 187, 188, 200, 207, 230 Asia Pacific, 139, 155 assessment, 35, 37, 38, 64, 175, 176, 177, 217, 226, 244, 269, 280, 284 ASTM International, 211, 225 atmosphere, xi, 44, 93, 181, 185, 186, 188, 283 attachment, 238, 239, 240 Australia, xiii, 20, 21, 27, 124, 137, 188, 210, 230, 280, 281, 285, 293 Austria, 22, 264, 267 automitive parts, x, 135 automotive sector, 121, 122, 124, 138, 139 awareness, xi, 9, 14, 20, 33, 166, 181, 308

B backyard decks, 219 bacteria, 85, 88, 90, 103, 121, 171, 204, 212, 242, 256, 257, 266 bacterial cells, 255 bacterial strains, 171, 232 barriers, vii, 24, 28, 31, 37, 222, 231, 318 Barriers in Waste to Energy, 8 base, xii, 10, 37, 74, 156, 191, 222, 267, 270, 275, 280, 281, 284, 285, 289 basic research, vii Bast Fibre, 137 benefits, ix, x, 57, 74, 76, 83, 103, 104, 118, 119, 122, 135, 154, 167, 168, 185, 222, 252, 269, 276, 283, 304 benzene, 171, 214, 312 Benzylation, 144 Beta particles, 52

billet scale (BS), 183, 192, 198 binding energies, 56 biocompatibility, xii, 227, 234, 235, 238, 239, 240, 244 Biocomposites, 121, 123, 125, 139, 147, 155 bioconversion, 118, 119, 120, 127 biodegradability, xii, 203, 204, 211, 212, 214, 216, 217, 223, 226, 227, 229, 234, 235, 237, 238, 261, 299 biodegradable materials, xi, 203, 213, 218 biodegradable nature, 299 biodegradable plastics, xi, 203, 207, 208, 210, 211 biodegradable wastes, 7, 253 biodegradation, xi, 88, 90, 118, 129, 178, 179, 203, 204, 205, 207, 211, 212, 213, 214, 215, 216, 217, 218, 222, 223, 224, 225, 226 biodiesel, ix, 10, 14, 39, 44, 132 biodiesel production, ix, 39, 44 bio-filler, 43, 77, 79, 81, 82 biofuel, 12, 16, 108, 127, 272 biogas, v, vi, viii, x, xii, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 94, 105, 107, 108, 110, 118, 119, 126, 127, 130, 131, 251, 252, 253, 254, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274 Biogas Investment, 260 biogas production, viii, xii, 1, 2, 3, 7, 8, 11, 13, 15, 17, 118, 130, 131, 251, 252, 253, 254, 256, 257, 259, 261, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274 biological processes, 204 Biological Recycling, 171 biologically active compounds, x, 135 biomass, xii, 9, 10, 11, 92, 93, 94, 110, 112, 128, 131, 136, 199, 204, 209, 212, 213, 214, 217, 243, 251, 252, 253, 254, 257, 262, 264, 267, 269, 270, 271, 272, 274, 298, 300 biomaterials, 81, 108, 242, 244, 245 biomedical applications, 204, 235, 241, 242 Biomedical Applications, 238 bionanocomposites, 132 bioplastics, vi, viii, 168, 203, 206, 207 biopolymer, 80, 211, 228, 231, 235, 255 biotic, 213, 214, 223 biotic environmental, 213, 223 black liquor, 140, 151, 155, 156 bleaching, 110, 117 blends, 170, 244, 281, 285, 287, 289, 315, 316, 317, 318, 320


Index blue, 53, 284, 290 blue 41 dye, 284 Boltzmann constant, 53 bonding, 136, 142, 149 bonds, 114, 213, 214, 228, 234, 299 bone, 94, 205, 235, 238, 239, 247 bottom-up and top-down techniques, 91 bricks, xi, xii, 21, 23, 27, 30, 181, 182, 183, 185, 186, 187, 188, 190, 191, 192, 193, 195, 196, 197, 198, 199, 200, 201, 202, 221, 275, 276, 280, 283, 284, 286, 288, 289, 291, 295 briquette ash, 183, 198 bromine, 63 building, vi, ix, x, xii, 14, 21, 30, 32, 34, 35, 36, 37, 38, 62, 69, 73, 74, 90, 104, 108, 124, 127, 135, 136, 154, 161, 181, 182, 183, 185, 187, 189, 190, 191, 192, 193, 195, 196, 197, 198, 199, 200, 201, 202, 205, 221, 226, 275, 276, 282, 283, 286, 288, 289, 290, 291 Applications, 69 Construction, vi, 181, 221 material, ix, x, 30, 32, 62, 69, 73, 135, 136, 154, 182, 183, 185, 187, 189, 191, 193, 196, 198, 202, 276 sector, x, 135, 154, 182, 192, 195, 275 building and construction sector, xii, 136, 275 building blocks, 30, 108, 127, 197, 198, 205, 221 burn, 222, 260, 300 burning of waste, 294, 312 businesses, 11, 258 butadiene, 69, 81, 145, 306, 312 by-products, x, 68, 73, 79, 93, 108, 109, 110, 111, 112, 113, 116, 117, 118, 119, 120, 121, 126, 127, 135, 154, 182, 183, 283

C C&DW management, 20, 33 calcination temperature, 182 calcium, 44, 58, 62, 74, 76, 78, 170, 173, 185, 188, 191, 199, 231, 232, 245, 269, 276, 287, 300 carbonate, 44, 62, 76, 78, 170, 173, 232 oxide, 44, 58, 188, 300 calcium carbonate, 44, 62, 76, 78, 170, 173, 232 California bearing ratio, 280, 281 CaO, ix, 39, 43, 44, 45, 46, 47, 56, 58, 65, 188 carbohydrate, 109, 118, 242, 257, 270

325 carbon dioxide (CO2), 24, 44, 94, 112, 140, 151, 167, 171, 172, 185, 186, 204, 212, 213, 214, 215, 216, 217, 252, 253, 254, 256, 257, 263, 283, 288, 310, 312 carbon emissions, 139, 192 carbon Fabrication, 93 carbon foodprint, x, 135, 155 carbon materials, 90 carbon monoxide, 171, 252, 256, 270, 312 carbon nanotubes, 90, 152, 240 carbon-based material, 84 carbonization, 69, 70 carboxyl, 156, 233 carboxymethyl cellulose, 241 case study, 34, 35, 36, 176, 201, 319 casein, 120, 132 casting, 122, 235, 299 CaTa2O6 Pr3+, 46, 47, 48, 51, 52 catalyst, 43, 44, 46, 93, 110, 111, 144, 172, 255 category a, 169 cathode, 96, 97, 98 Cathodoluminescence, 54, 55 CaTiO3 Pr3+, 46, 47, 48, 50, 51, 53, 55, 56 cattle, 10, 94, 253, 257, 264, 270, 272, 273 cellulose, xiii, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 120, 121, 122, 126, 127, 128, 129, 130, 132, 133, 136, 141, 142, 143, 146, 147, 149, 151, 152, 156, 157, 169, 178, 213, 214, 218, 228, 241, 247, 255, 268, 293, 299, 300, 301 nanofibers, 111, 113, 116, 117, 127, 133, 142, 143, 156 cellulose fibre, 142, 143, 151, 152, 156, 157 cement mortar, 28, 31, 32, 279, 282, 290 cementing Bricks, 185 cementitious binder, 183, 191 centipedes, 90 Ceramic, ix, 27, 30, 39, 56, 76, 183, 189, 199, 200, 238, 239, 247, 287 industry, ix, 39, 287 waste, 183 Ceramics, 36, 58, 290, 291 CH4, 204, 212, 214, 216, 252, 264, 268 challenges, viii, ix, x, xi, xii, 2, 5, 16, 17, 19, 39, 90, 107, 119, 121, 123, 159, 162, 175, 177, 182, 194, 201, 208, 224, 227, 229, 252, 258, 259, 260, 262, 266, 267 charge transfer, 99


326

Index

charpy impact strength, 148 chemical bonds, 110, 255 chemical composition, xiii, 31, 65, 76, 92, 156, 189, 191, 293 chemical degradation, 213 chemical industry, 63, 231 chemical inertness, 214 chemical interaction, 145 chemical pre-treatment, 113, 142, 273 chemical properties, 75, 215, 223, 279, 299 chemical reactions, 23, 253 Chemical Recycling, 171, 173, 176 chemical stability, 54, 98 chemical structures, 147 chemical vapor (CVD) deposition, 92, 93, 94 chicken manure, 15, 119, 131, 261, 263, 272 chimneys, 184, 286 China, 2, 15, 17, 18, 20, 21, 23, 30, 34, 35, 36, 64, 73, 124, 126, 127, 137, 138, 160, 164, 184, 186, 187, 188, 191, 210, 224, 231, 296 chitin, vi, xii, 213, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248 carbamates, 234 derivatives, xii, 227, 229, 234, 244, 245 whiskers, 232, 233, 235, 247 chitosan, 228, 229, 231, 234, 235, 238, 239, 240, 241, 242, 243, 244, 245, 247, 248, 249 chloride anion, 113 chlorination, 109 chlorine, 63, 112 chloroform, 115, 144 chocolate, 92 chopping, xii, 251 chromatography, 216 chromium, ix, 61, 65, 312 cigarette butts, 183 cities, ix, 11, 43, 61, 73, 164, 177, 210, 221 Class C, 188 class C fly ash, 192 Class F, 188 class-C FA, 191 classification, 27, 33, 169, 200, 314 clay bricks, 184, 186, 190, 191, 192, 196, 197, 198, 199, 201, 276, 286 clay-brick-powder, 285, 288, 291 cleaning, 43, 89, 95 climate change, xii, xiii, 2, 79, 90, 184, 204, 251, 252, 258, 303

clinker, 279, 312 CO2, 24, 44, 112, 140, 151, 167, 172, 185, 204, 212, 214, 216, 217, 252, 263, 288, 310 coal, ix, xi, 7, 61, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 79, 81, 89, 90, 97, 120, 181, 182, 187, 188, 190, 191, 195, 199, 201, 310, 312 coastal area, 42, 43, 228 coatings, 81, 163 cobalt, 265, 266, 273 cockroach legs, 92 combustion, xi, xiii, 46, 65, 66, 71, 72, 73, 74, 77, 79, 81, 179, 181, 188, 193, 195, 198, 253, 293, 294, 312 commercial, viii, xii, 1, 2, 7, 8, 10, 11, 12, 13, 16, 43, 48, 62, 76, 94, 124, 163, 203, 207, 225, 227, 228, 232, 233, 258, 261, 270, 296 commercial and environmental needs, xii, 203 commercial applications, xii, 13, 227, 228 commodity, 204, 205, 206, 316, 317 communities, vii, 62, 64, 78, 111, 125 compaction, 29, 182, 186, 280, 281, 285 compatibility, 123, 144, 170, 229, 239 competitive advantage, 125 complement, 168, 174 complications, 85, 104, 240 composite demand, 138 composite market, 137, 139 composite materials, xiii, 136, 137, 140, 141, 145, 154, 170, 173, 192, 214, 240, 293, 299 Composite(s), xiii, 69, 70, 77, 78, 79, 80, 81, 82, 95, 108, 121, 122, 123, 124, 127, 128, 132, 133, 136, 137, 138, 139, 140, 141, 143, 144, 145, 146, 147, 148, 151, 152, 153, 154, 155, 156, 157, 169, 173, 177, 178, 191, 192, 201, 214, 221, 234, 235, 236, 237, 238, 239, 240, 241, 243, 246, 247, 248, 293, 299, 318, 320 composition, xii, xiii, 21, 30, 31, 38, 65, 74, 76, 92, 94, 156, 170, 188, 189, 191, 192, 195, 204, 209, 213, 251, 252, 257, 267, 268, 272, 293, 299, 306, 311, 316 compost, 85, 87, 88, 89, 103, 104, 204, 217, 218, 222, 223, 226 compost heat system, 89 Compostable plastic, 212 composting, ix, 83, 88, 89, 90, 103, 104, 208, 209, 210, 212, 214, 215, 216, 217, 218, 224, 225, 294 conditions, 214, 215, 217 process, ix, 83, 89, 90, 103


Index compounds, 44, 46, 62, 63, 87, 108, 110, 112, 117, 127, 144, 212, 213, 218, 252, 255, 256, 257, 311 compressed earth brick(s), xii, 182, 183, 197, 198, 275 compression, 31, 149, 170, 186, 247, 314 compression molding, 149, 247 compressive strength, 30, 31, 191, 193, 196, 280, 281, 282, 283, 285, 286, 287, 288, 289, 291 conceptualization, 63 concrete aggregate, 25, 31, 34, 281 Concrete(s), v, viii, 19, 20, 21, 23, 25, 27, 28, 29, 30, 31, 32, 34, 35, 36, 37, 38, 65, 74, 79, 81, 95, 185, 186, 189, 190, 191, 192, 197, 199, 210, 222, 276, 281, 283, 284, 285, 286, 288, 289, 290, 291 conduction band, 49, 51 conductivity, 80, 94, 147, 189, 192, 241, 249, 281 conservation, xii, 20, 24, 33, 58, 167, 192, 251, 276, 313 constituents, 25, 109, 195, 228, 240 construction, viii, x, xi, xii, 10, 19, 20, 21, 23, 24, 25, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 65, 73, 74, 79, 84, 95, 124, 135, 136, 137, 139, 153, 154, 159, 160, 163, 181, 182, 183, 185, 186, 187, 190, 191, 192, 193, 195, 196, 197, 200, 201, 202, 204, 209, 221, 222, 226, 231, 275, 276, 277, 282, 283, 284, 286, 287, 290, 298, 318 Construction and Demolition (C&D), 37, 276 Construction and Demolition Wastes (C&DW), viii, 19, 20, 31, 35, 36, 37, 282 construction industry, viii, xi, 19, 20, 21, 25, 27, 35, 36, 38, 65, 79, 95, 181, 185, 190, 193, 196, 221, 287 construction materials, xi, 30, 32, 153, 181, 182, 183, 191, 201, 276, 283 construction sector, xii, 182, 187, 193, 195, 275 consumers, 64, 164, 172 consumption, xi, 10, 11, 16, 20, 24, 32, 126, 137, 138, 139, 159, 160, 164, 167, 193, 206, 207, 210, 259, 261, 283, 317, 318 consumption patterns, 20 contact time, 282, 286 containers, 161, 170, 178, 209, 220, 294 contamination, 56, 92, 168, 169, 171, 172, 174, 230, 294 contour, 99, 101 conventional bricks, 182, 183, 186, 192 conventional energy sources, 90 conventional hollow burnt clay bricks, 191 conventional plastics, 204, 210

327 cooking, 15, 161, 253 cooling, 66, 98, 122, 140, 141, 231, 247 copolymer, 80, 145, 213 copolymerization, 245 corn stover, 127, 128, 129, 130, 131, 132, 261, 262, 263, 264, 272, 273 cost, x, xi, xiii, 2, 4, 10, 13, 16, 27, 28, 30, 46, 62, 63, 71, 76, 87, 89, 90, 95, 96, 102, 108, 111, 113, 117, 118, 120, 124, 135, 139, 147, 159, 160, 167, 169, 177, 181, 182, 185, 189, 191, 192, 196, 200, 221, 226, 229, 231, 253, 267, 270, 276, 284, 286, 294, 298, 303, 314, 315, 317 coulombic force, 49 coupling agent, 139, 145, 147, 151, 152, 157, 170 covering, 76, 161, 222 crab-shells, 228 296 crop residue, 262 crop rotations, 271 crops, xii, 77, 79, 85, 109, 224, 251, 253, 259, 261, 262, 265, 267, 268, 269, 270, 271, 274, 295, 296 crude oil, 166 crushed brick blends, 281, 285, 289 crushed concrete, 27 crushed masonry, 27 Crustacean shells, 228 crystal structure, 213 crystalline, 44, 112, 113, 115, 126, 185, 188, 228, 231, 232, 246 crystalline structure, 228 crystallinity, 111, 117, 122, 129, 146, 213, 216, 236, 287 crystallization, 122, 245, 296 culture, xi, 7, 159, 222, 296 cytocompatibility, 239, 246, 248

D dairy manure, 119, 131, 264, 273 damping index, 145 DEA, 13, 17, 84, 302 deacetylation, 229, 234, 243 dead animal waste, 83 decay, 49, 51, 222 decay curve, 49, 51 decision makers, 174 decomposition, 62, 85, 215, 294 deconvoluted glow-curve, 52


328

Index

deconvolution, 51, 52 defects, 29, 92, 239 defibrillation, 110, 111, 117, 233 Degassing, 142 degradation mechanism, 213, 216 degradation process, xii, 40, 53, 54, 55, 56, 84, 103, 109, 111, 112, 117, 127, 128, 131, 136, 146, 150, 168, 171, 178, 205, 206, 211, 212, 213, 214, 216, 217, 218, 223, 227, 228, 239, 242, 254, 255, 257, 266, 270, 273, 294, 315 degradation rate, xii, 168, 227, 228 Department of Environmental Affairs (DEA), 17, 84 depolymerization, 110, 244 depopulate, 51 deposition, 92, 98 deposits, 24, 93, 239 depth, 51, 53, 72 derivatives, xii, 94, 98, 218, 227, 229, 234, 241, 244, 245 developed countries, 2, 14, 15, 32, 85, 187, 189, 221, 230, 270 developed nations, 13 developing countries, 2, 13, 16, 64, 68, 177, 186, 187, 230, 271, 294 developing nations, 207 dialysis, 115 dibutyryl chitin, 234, 244 Diesel fuel, 45, 56 different frequency, 48 differential scanning calorimetry, 122, 244 diffusion, 98, 239, 283 digestibility, 126, 131, 263 digestion, 15, 118, 119, 130, 131, 253, 255, 256, 257, 261, 262, 263, 264, 265, 266, 268, 270, 271, 272, 273 dimers, 214 dimethylformamide, 235 direct measure, 216, 217 diseases, 77, 78, 79, 104, 304 dispersion, 80, 98, 115, 117, 123, 143, 144, 235, 241 displays, 47, 48, 53, 54, 156 disposal, xi, 7, 8, 12, 16, 20, 23, 27, 32, 41, 70, 71, 72, 73, 76, 77, 78, 79, 84, 85, 87, 108, 159, 163, 165, 166, 178, 181, 182, 190, 194, 195, 201, 204, 207, 208, 224, 229, 230, 231, 277, 284, 294, 295, 298, 304, 307, 318 dissociation, 54, 99 distilled water, 142, 143

distribution, 31, 52, 65, 76, 150, 161, 189, 208, 261, 280, 281, 287, 289, 291, 314 dog feces, 92 DOI, 18, 81, 156, 157, 272 domestic and agricultural organic waste, ix, 83 domestic food, ix, 83 dosage, 55, 286 dosimetry, 47 drainage, 163, 221, 222, 285 dried-clay bricks, 182 drought, 258, 260, 261, 267 drug delivery, 231, 234 drying, 86, 115, 123, 142, 144, 147, 169, 174, 276 DSC, 122, 128, 216 dumping, x, xi, 23, 32, 40, 43, 66, 77, 79, 85, 107, 159, 294 dumping sites, x, 23, 40, 43, 79, 85, 107 durability, 31, 32, 160, 167, 185, 192, 197, 222, 276, 281, 285, 286, 288, 291

E Earthworms, 90 Eastern Europe, 318 ECM, 239, 240 eco-friendlyness, 182 ecological challenges, viii, 19, 182 economic development, vii, 30, 125, 210 economic evaluation, 176 economic growth, ix, 2, 30, 39, 83, 139, 207, 252, 259, 260, 289 Economic Growth of Plastics, 206 economic indicator, 137 economic policy, 260 economic problem, 193 economic sector, viii, 19 economics, 30, 224, 258, 319 Ecotoxicity, 218 education, 9, 164 effluent, 84, 270, 294 egg, 76, 77, 79, 81 eggshells, v, ix, 61, 62, 64, 76, 77, 78, 80, 81 electricity, ix, 2, 4, 6, 7, 8, 9, 10, 11, 13, 14, 15, 17, 39, 48, 49, 59, 68, 79, 89, 172, 174, 252, 253, 258, 259, 260, 267 generation, 79 electrolyte, 96, 248


Index electron, 46, 47, 49, 51, 52, 53, 54, 55, 56, 80, 94, 95, 99, 101, 152, 233, 256, 281, 317 electron beam irradiation, 53, 54, 55, 56, 80 electron microscopy, 46, 152 Electron Stimulated Surface Chemical Reaction (ESSCR), 54 electron trapping centers, 49, 51, 52, 53 electron traps, 51 electrons, 49, 51, 52, 53, 96, 97, 102 electrospinning, 232, 235, 238, 240, 243, 246 elongation, 148, 149, 152, 216, 235 emission, 47, 48, 49, 51, 99, 101, 185, 283, 312 emission intensity, 99 emission range, 49, 51 employees, 9, 173 employment, 168, 187, 194, 261, 278, 279, 317 employment opportunities, 194, 261, 278 Energy, ix, xii, xiii, 2, 3, 4, 7, 9, 10, 11, 14, 15, 16, 17, 20, 24, 30, 36, 46, 49, 51, 52, 53, 54, 68, 72, 79, 83, 85, 89, 90, 93, 94, 96, 97, 98, 99, 101, 102, 103, 109, 111, 112, 113, 118, 120, 121, 124, 126, 127, 130, 131, 140, 147, 148, 152, 163, 164, 165, 166, 167, 168, 171, 172, 173, 177, 182, 184, 185, 186, 194, 196, 208, 209, 215, 241, 251, 252, 253, 254, 255, 256, 259, 262, 263, 266, 268, 269, 270, 271, 274, 276, 283, 286, 293, 294, 298, 300, 307, 308, 313, 315, 316, 318, 319 consumption, 20, 24, 111, 124, 126, 127, 252 gap, 99 energy consumption, 20, 24, 111, 124, 127, 252 energy density, 96, 97 energy efficiency, 4, 118, 241 energy input, 113, 182, 269, 274 Energy Policies and Regulation in South Africa, 3 Energy Policy White Paper, (1998), 3 energy recovery, 109, 163, 165, 166, 167, 172, 173, 177, 208, 209, 307, 308, 318, 319 energy security, 2 energy source, ix, 3, 16, 83, 90, 171, 252, 255 Energy Storage Systems, 94, 96, 103 energy supply, 3, 49, 90, 252, 300 energy transfer, 98, 101 engineering, x, 24, 135, 136, 154, 185, 199, 238, 239, 281, 285, 308, 317 engineering materials, x, 135 entrepreneurs, vii, viii, 1, 2, 3, 11, 16 environment, vii, viii, ix, xi, xiii, 3, 19, 20, 23, 27, 30, 39, 40, 56, 83, 84, 87, 89, 103, 108, 165, 166, 167, 168, 172, 174, 181, 184, 185, 192, 195, 201,

329 202, 207, 208, 211, 212, 214, 217, 218, 221, 222, 223, 224, 226, 242, 258, 276, 278, 284, 286, 289, 293, 294, 297, 307, 318 environmental awareness, vii, 124, 211 environmental benefits, ix, 74, 83, 185, 252, 283 environmental concerns, 121, 136, 182, 195, 228, 235, 298, 301, 312 environmental conditions, xii, 211, 212, 213, 225, 251, 317 environmental contamination, 195 environmental crisis, 172, 241 environmental degradation, 294 environmental factors, 211, 212, 223 Environmental friendly plastics definition, 204 environmental impact, viii, 11, 19, 20, 33, 41, 73, 87, 125, 162, 165, 195, 210, 222, 224, 230, 277 Environmental Impact Assessment (EIA), 5 environmental issues, 24, 163, 206, 231 environmental management, 224 environmental policy, 224 environmental protection, 23, 207, 271, 295 Environmental Protection Agency, 209 environmental services, 195, 277 environmental sustainability, 194 environmental threats, 299 environmentally biodegradable plastics, 204, 218 environments, 62, 109, 217, 223 enzymatic hydrolytic degradation, 213 enzyme, 110, 112, 114, 115, 116, 117, 118, 129, 130, 213, 255, 264, 266 equipment, 64, 141, 186, 209, 218, 219, 296, 309, 310, 314 erosion, 88, 309 Escherichia coli (E.coli), 85, 129, 239 ester, 112, 138, 213, 235, 245 esterase enzymes, 213 ethanol, xiii, 46, 47, 118, 121, 128, 131, 144, 234, 262, 293, 300 ethylene, 145, 170, 178 eucalyptus, 147, 156 eucalyptus pulp, 147 Europe, 14, 21, 73, 81, 124, 138, 139, 160, 206, 209, 221, 254, 305, 318 European Parliament, 208 European Polysaccharide Network of Excellence (EPNOE), 206, 223 European Union, 14, 21, 63, 64, 72, 120, 126, 160, 209, 224, 306, 307, 320 evaporation, 93, 118


330

Index

evidence, 20, 56 evolution, 216, 217, 318 evolution tests, 216 excitation, 47, 52, 99, 101, 102 exoskeleton, xii, 227, 228, 229, 230, 231 exoskeleton of lobster, 229 experimental condition, 91, 286 experimental design, 288 exploitation, 108, 193 exposure, 63, 225, 226, 282 extracellular matrix, 239, 240 extraction, 11, 13, 108, 109, 113, 115, 116, 117, 127, 172, 184, 193, 228, 231, 232, 242, 282, 284, 286, 299 extrusion, xi, 133, 163, 169, 170, 203, 205, 237, 247, 300

F fabrication, 43, 46, 47, 90, 93, 94, 95, 102, 103, 147, 243, 246, 299 fabrication of materials, 299 fabrication process, 46 FaL-G bricks, 191 farmers, 10, 13, 89, 252, 258, 260, 261, 300 farms, 9, 14, 15, 17, 258, 261, 300 feedstock, 13, 15, 124, 174, 221, 231, 255, 268, 269, 270, 274 fermentation, xii, 117, 120, 121, 127, 131, 132, 232, 251, 254, 255, 257, 262, 264, 267, 270, 272, 273 fermentation technology, xii, 251, 271 fertility, 84, 258 fertilization, 269 fertilizers, 89, 258, 261, 269 Fertilizers and graphene, ix, 83 fiber content, 268 fibers, x, 80, 107, 110, 111, 112, 113, 115, 116, 117, 121, 123, 124, 126, 127, 130, 132, 152, 156, 157, 169, 170, 196, 211, 233, 238, 240, 247, 299, 300 fibre-fibre interface, 150 fibrillation, 141 fibroblasts, 240, 242 fibrous matter, xiii, 293 field crops, 254, 270 Field Emission Displays, 53 filler/additive ingredient, 205 fillers, ix, 61, 62, 63, 64, 80, 143, 145, 151, 152, 157, 169, 173, 235, 238, 304, 306

Film plastics, 221 films, 128, 149, 161, 171, 204, 217, 223, 225, 226, 235, 237, 238, 241, 243, 245, 246, 247 financial, xiii, 3, 11, 12, 20, 33, 57, 68, 103, 127, 168, 169, 175, 196, 230, 278, 289, 294, 301, 303, 315 financial resources, 3 financial support, 127, 301 fire resistance, 30, 199 fire retardants, 222 fired clay bricks, 182, 183, 186, 193, 196, 198, 199 fishery industries, 228, 230 fishery waste, 228, 229, 231 flame, 23, 62, 63, 64, 66, 69, 70, 76, 77, 79, 80, 81, 222, 265 Flame retardant fillers, ix, 62 flame retardant material, 62, 69 flame retardants, 62, 63, 80, 81 flammability, ix, 62, 77, 80, 81, 82, 113, 152, 304 flax, 139, 145 Flexform, 124, 137 flexibility, 94, 122, 213 flexural strengths, 192 flooding, 163, 193 flooring, 153, 222 flour, 151, 157, 199 Flowable Fill, 74 fluidized bed, 193, 198, 319 Fly ash, ix, xi, 31, 37, 61, 62, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 79, 81, 181, 182, 183, 186, 188, 189, 190, 191, 192, 193, 195, 196, 197, 198, 199, 200, 201, 202, 283, 290 foamed concrete, 281 Food, xi, 10, 13, 76, 77, 78, 84, 85, 88, 94, 104, 109, 120, 136, 159, 160, 161, 168, 204, 209, 210, 217, 224, 228, 231, 234, 239, 242, 252, 253, 258, 259, 260, 261, 270, 300 packaging materials, 217 poisoning, 85 food additive, 78 food industry, 13, 77 food production, 260 food products, xi, 159 food security, 261 foodborne illness, 85 force, 21, 49, 116, 124, 125, 140 formation, 55, 56, 70, 88, 117, 123, 130, 191, 217, 233, 236, 238, 253, 269, 288, 312 formulation, 62, 218, 220, 221, 223


Index fossil fuel, 14, 46, 108, 120, 121, 168, 204, 205, 252 fracture toughness, 140 fragments, 29, 212, 215, 233 France, 22, 27, 124, 175, 209 Free Basic Alternative Energy Policy, (2007), 3 fruits, 84, 88, 103 FTIR, 112, 156, 161, 246 funding, viii, 1, 12, 33, 57, 103, 125, 186, 196, 289 Fungi, 88, 90, 103, 112, 171, 204, 212, 214, 228, 231 fungus, 113, 129

G gamma radiation, 233, 317 garden rakes, 218, 220 Gardeners, 89 Gas evolution tests, 217 gasification, xiii, 4, 293 GDP, 11, 12, 108, 261, 278 gel, 46, 97, 117, 141, 287 gelation, 232, 244 General Policies, 3 geometry, 51, 147 geopolymeric porous concretes, 31 geopolymerization, 183, 288 geopolymers bricks, 182 Germany, viii, 2, 14, 15, 16, 20, 22, 23, 27, 137, 191, 209, 267, 271 global demand, 30, 185 global total share, 139 global warming, xii, xiii, 2, 24, 79, 109, 118, 163, 166, 184, 204, 251, 269, 303 glow, 49, 51, 52, 53 Glow curves, 52 glucose, 129, 234 government initiatives, x, 107, 108 government policy, 183 governmental regulations, xi, 159 governments, 64, 164, 190, 231, 298, 301 granite fines, 183, 198 granules, 140, 222 Graphene Fabrication, 90 graphene flakes (GFs), 92 graphene gel, 97 graphene oxide (GO), 94 graphene sheet, 94 graphite, 62, 80, 91, 94, 96, 97, 98, 152 grass, 92, 128, 164, 215, 253, 268, 269, 274, 295

331 grass blades, 92 green, viii, x, xi, xiii, 2, 7, 11, 19, 53, 94, 107, 108, 110, 113, 117, 118, 121, 128, 135, 136, 139, 140, 145, 149, 151, 153, 183, 185, 196, 200, 202, 203, 225, 252, 260, 265, 293 composites, x, 107, 108, 128, 135, 145, 225 materials, xi, 203 Greengran B.V, 124, 137 greenhouse gases (GHG), viii, xii, xiii, 19, 20, 21, 108, 109, 166, 172, 184, 185, 195, 251, 258, 300, 303, 304 emissions, 4, 138, 182, 266 gross domestic product, 11, 12, 108, 261 ground state, 99 ground tire rubber, xiii, 303, 304, 318 groundwater, ix, 61, 66, 182, 294 growth, x, 11, 13, 20, 32, 88, 93, 115, 124, 135, 137, 138, 139, 154, 155, 165, 171, 193, 206, 207, 211, 217, 238, 240, 248, 252, 256, 258, 259, 267, 270 growth rate, x, 135, 139, 206 Growth, Employment and Redistribution, 260 guidance, viii, 2, 16 guidelines, 17, 230 Guinea, 295

H H2S or NH3, 94 habitat, 204, 222 halogenated flame retardants, 63, 64 hardwood, vi, x, 135, 136, 140, 145, 146, 149, 151, 153, 154, 156 harvesting, x, xii, 107, 109, 118, 125, 251, 265, 267, 296, 301 hazardous materials, 23 hazardous waste, 4, 8, 73, 310 hazards, 64, 85, 160, 172 HDPE, 161, 170, 171, 176, 178, 300, 316, 317 health, x, xi, 9, 40, 42, 56, 62, 63, 64, 78, 81, 84, 124, 125, 135, 154, 159, 160, 163, 166, 193, 224, 229, 230, 297 and environmental effects, 64 care, xi, 159, 224 effects, 62, 63 problems, x, 135, 154 Heat, ix, 9, 10, 14, 30, 66, 69, 77, 79, 83, 88, 89, 90, 95, 98, 103, 108, 138, 140, 152, 171, 172, 185,


332

Index

192, 208, 245, 246, 253, 256, 294, 305, 310, 312, 314 insulation, 30 heat conductivity, 192, 314 heating rate, 51, 53 heavy metals, 189, 192, 256, 282, 312 Hemicellulose(s), xiii, 108, 109, 110, 111, 112, 113, 117, 120, 126, 128, 129, 136, 142, 143, 218, 255, 268, 293, 299 hemolytic uremic syndrome, 85 hemp, 145, 269, 270 Henri Braconnot, 228, 242 High density polyethylene (HDPE), 161 high strength, 122, 151, 191, 237, 240, 241 High Temperature Applications, v, 61, 78 high temperatures, 183 higher temperature applications, ix, 62, 64, 77, 312 high-intensity ultrasonification, 142 history, 64, 136 hollow concrete blocks, 191 home heater, 89 Home Lighting, 48 homogeneity, 29, 46, 47, 238 Hong Kong, 20, 21, 23, 280 hot melt extrusion, xi, 203, 205 housing, 200, 221, 222, 226 human health, 30, 63, 64, 103, 167, 208, 258, 307 humidity, 140, 143, 211, 212, 236 hybrid, 35, 157, 238, 245, 265, 267 hydrocarbons, 172, 270, 311, 312 hydrogels, 239, 248 hydrogen, 70, 109, 112, 123, 136, 142, 171, 252, 254, 255, 256, 312, 318 bonds, 123 chloride, 171 gas, 256 peroxide, 112 sulfide, 252 hydrolysable, 213 hydrolysis, 110, 111, 112, 114, 115, 116, 117, 118, 120, 121, 128, 129, 130, 146, 157, 213, 225, 232, 233, 234, 235, 253, 254, 255, 264, 300 hydrolytic, 114, 150, 213, 214, 215 hydrolyze triacylglycerol (fat), 213 Hydrophilic, 123, 143, 144, 169, 212 filler, 143 hydrophilicity, 144, 213 hydrophobic, 123, 143, 169, 212, 214 hydrophobic polymer matrix, 123

hydrophobic properties, 212 hydrophobicity, 144, 213 hydroxide, 62, 80, 111, 142, 143, 185, 261, 284 hydroxyapatite, 81, 238 hydroxyl, 46, 69, 70, 123, 136, 144, 213, 233, 300 hydroxyl group, 46, 123, 136, 144, 233, 300 hydroxypropyl chitin, 234, 244

I ideal, 96, 116, 238, 299 IEA, 71, 72, 81 images, 45, 46, 58, 98, 99, 104, 105, 116, 148 impact assessment, 5, 11, 224 impact strength, 122, 148, 151 Importance of Coal, 68 impregnation, 143, 144 improvements, 35, 145, 147, 186, 201, 259, 262 impurities, 62, 63, 119, 167 incineration, 4, 11, 109, 166, 167, 172, 174, 179, 208, 210, 294, 307, 310 income, 12, 13, 221, 252, 258, 260, 278, 279 incompatibility, 146, 173 incubation period, 239 incubation time, 264 India, xiii, 2, 18, 59, 64, 124, 137, 138, 186, 187, 188, 190, 191, 199, 293, 295, 296 induced biodegradation, 204 industrial lignins, 140, 151, 155 industrial sectors, 304 industrial waste, ix, xi, 11, 25, 61, 65, 94, 169, 181, 183, 192, 193, 196, 200, 269, 274, 283, 290 industrialization, xi, 2, 21, 165, 181, 187, 210 industry, vii, viii, ix, xi, 1, 7, 9, 10, 11, 12, 13, 15, 16, 18, 19, 20, 21, 25, 27, 35, 36, 38, 39, 48, 56, 62, 63, 65, 73, 77, 79, 90, 95, 108, 123, 124, 125, 136, 137, 138, 139, 151, 154, 155, 160, 166, 181, 183, 185, 188, 190, 191, 193, 196, 206, 211, 221, 230, 231, 236, 258, 259, 260, 261, 278, 287, 294, 296, 305, 308, 313, 318 infancy, 2, 9, 16, 123, 298 information sharing, 173, 174 infrastructure, 12, 30, 36, 43, 164, 165, 166, 169, 172, 173, 174, 224, 231, 283 insulation, x, 23, 30, 37, 77, 80, 135, 154, 191, 220, 221, 222 integration, 139, 310 integrity, 212, 239, 240


Index intellectual property, 125 intensive farming, 258 interface, 55, 99, 101, 144, 150 interfacial adhesion, 69, 121, 143, 144, 317 interfacial bonding, 235 International Organization for Standardization (ISO), 211, 212 international standards, 223 Intumescent Flame Retardant, 76, 77 ions, 96, 97, 98, 114, 147, 236, 283, 286 irradiation, 53, 54, 55, 56, 80, 316, 318, 320 Isocyanate treatment, 144 isolation, 202, 228, 299 isoprene, 214 isotherms, 282, 286 issues, viii, 1, 34, 120, 160, 163, 222, 267, 284, 294, 308

J Japan, ix, 2, 20, 21, 27, 61, 73 job creation, 11, 24, 261, 278, 308

K kenaf, 130, 139, 145, 147, 155, 156 fibres, 145, 147, 155 Kenya, 163, 164 keratinocytes, 240, 242 kiln firing, 183, 185, 192 kinetic parameter, 51, 53 kinetic parameters, 51 kinetics, 51, 52, 286 kitchen waste, 261 KOH, 111, 142, 233, 236 KwaDlangezwa, 1, 19, 39, 61, 107, 135, 159, 181, 203, 227, 251, 275, 293, 303 KwaZulu Natal, 19, 61, 107, 159, 227, 251, 275, 293, 303 Kyoto protocol, 288

L laboratory controlled composting test, 216 laboratory studies, 215 Lacey, Harvey, 221 lack of confidence, 28 lactic acid, 225, 231, 244, 256

333 land reclamation, 25 Landfill, vi, x, xi, xii, xiii, 2, 3, 7, 8, 9, 10, 11, 12, 13, 15, 20, 21, 22, 23, 24, 25, 28, 33, 35, 40, 43, 62, 70, 71, 72, 76, 77, 79, 84, 87, 107, 108, 109, 125, 159, 160, 162, 163, 165, 172, 174, 181, 189, 194, 195, 203, 204, 205, 209, 210, 227, 228, 229, 230, 252, 253, 263, 276, 288, 294, 298, 303, 304, 307 disposal, 294 site, xi, xiii, 9, 20, 24, 76, 77, 79, 87, 125, 159, 160, 162, 163, 165, 174, 182, 194, 203, 204, 205, 209, 210, 230, 252, 288, 298, 303, 304, 307 Landfilling, 16, 167, 172, 304 landfills, x, xii, 2, 7, 8, 9, 10, 11, 12, 13, 20, 22, 70, 71, 72, 77, 87, 107, 108, 109, 125, 160, 162, 172, 189, 194, 227, 228, 229, 276, 294, 298 landscape, 30, 184, 185, 222 laws, 5, 7, 10, 72, 73 leaching, 30, 35, 36, 172, 282 lead, xii, 16, 23, 85, 98, 118, 120, 124, 139, 207, 246, 251, 266, 276, 294, 301, 312 leakage, 71, 77, 125 Legal Frameworks, 72 legislation, viii, 1, 3, 10, 13, 16, 20, 73, 194, 207, 208, 229, 277, 307 Legislation Applicable to Working with Municipality, 5 Legislation(s), viii, 1, 3, 10, 13, 16, 20, 73, 162, 194, 207, 208, 229, 277, 307 life cycle, 35, 163, 175, 179, 208, 269 light bulb, 48 light emitting diodes, 47 light transmittance, 123 Lightweight, xi, 76, 136, 138, 159, 160, 182, 184, 276 Lignin, xiii, 108, 109, 110, 111, 112, 113, 120, 121, 126, 128, 129, 136, 140, 142, 151, 155, 156, 214, 215, 218, 226, 268, 293, 299 lignocellulose, 214, 264 limestone, 44, 192, 201, 231, 281 Limpopo, 49 line markings, 48 lipase, 213 liquids, 113, 117, 119, 120, 127, 129, 248 Listeria monocytogenes, 85 Lithium-ion battery, 96 livestock, x, 107, 109, 163 local government, 11, 17, 210, 278, 297


334

Index

Los Angeles abrasion loss, 280 Louisiana, 296 low cost, x, xi, 63, 76, 103, 108, 113, 124, 135, 147, 159, 160, 169, 181, 182, 192, 200, 221, 229, 231, 241, 286 low density polyethylene, 121, 132 low risk, 64, 78 low temperatures, 94, 113 Low-density polyethylene (LDPE), 161 luminescence, 44, 47, 48, 49, 50, 51, 54, 55, 56, 58, 99 luminescent material, ix, 39, 48 luminescent paints, 48

M machinery, 46, 168, 260, 294 magnesium, 62, 76, 80, 120, 131, 188, 300 maize crop, xii, 251, 265, 270 maize stalk, xi, 114, 116, 121, 132, 133, 203, 207, 261, 262 maize stover, x, 107, 108, 110, 111, 112, 113, 115, 120, 273 maize waste, xii, 130, 251, 259, 262, 264, 265, 270, 273 majority, 12, 23, 74, 108, 109, 160, 298 maleated polypropylene (MAH-PP), 145, 151 mammals, 160 management, viii, x, xi, xii, xiii, 2, 4, 6, 7, 11, 17, 19, 20, 21, 27, 32, 33, 34, 35, 40, 41, 43, 85, 86, 87, 107, 125, 138, 162, 164, 165, 166, 175, 177, 181, 182, 187, 194, 195, 201, 202, 208, 209, 210, 211, 224, 229, 230, 251, 266, 276, 277, 278, 294, 297, 298,301, 304, 307, 308, 310, 319, 320 manufacturing, xi, xii, 21, 57, 63, 64, 65, 68, 79, 95, 124, 139, 147, 160, 167, 169, 174, 181, 183, 184, 185, 186, 188, 189, 190, 192, 198, 259, 275, 280, 305, 306 manure, 13, 14, 15, 16, 88, 94, 119, 131, 252, 253, 261, 263, 264, 266, 268, 270, 272, 273 marine environment, 175, 218, 230 Market, vi, 11, 12, 17, 123, 124, 133, 137, 155, 203, 258, 259, 278 forecast, 137 Market and Demand, 137, 278 market penetration, 317 market segment, 137, 138 market share, vii, 206, 315

market structure, xiii, 12, 275 marketing, 201, 208, 224 masonry building bricks, 192 mass, 140, 141, 150, 257, 268, 280, 284, 287 material handling, 191 material resources, 283 matrix, 3, 62, 69, 70, 99, 121, 123, 132, 139, 142, 143, 144, 145, 146, 147, 149, 151, 169, 214, 218, 235, 283, 295, 317 mechanical properties, 28, 30, 76, 81, 94, 121, 124, 132, 136, 140, 143, 144, 145, 147, 151, 152, 156, 157, 169, 177, 178, 192, 199, 200, 202, 216, 235, 238, 239, 241, 243, 246, 248, 279, 281, 285, 286, 288, 299, 316, 317 Mechanical Recycling, 168 mechanical strength, 191, 192, 212, 236, 280 media, 9, 129, 217, 314 Mediterranean, 160, 161, 163, 175, 296 medium composition, 216 melt, xi, 170, 203, 205, 222, 237 melting, 44, 113, 122, 193, 212, 216 melting temperature, 213, 216 membranes, 221, 231, 236, 238, 243, 248, 249 mercaptochitin, 234, 245 mercury, ix, 61, 65, 282, 312 mesenchymal stem cells, 241 Mesophiles, 90 metal ion, xii, 227, 282, 286 metals, ix, 21, 27, 61, 65, 298 methane fermentation process, xii, 251, 254 methane gas, 11, 94, 265 Methanogenesis, 256 methanol, 256, 263 methodology, 284 methyl methacrylate, 245 methylcellulose, 300 microbial communities, 254, 256 microfibrillated cellulose (MFC), 130, 147 micronutrients, 270 microorganism, 171, 215, 239, 256 Microorganism(s), 88, 136, 167, 171, 178, 204, 205, 211, 212, 213, 214, 215, 239, 253, 254, 255, 256, 262, 272 microscopy, 116, 286 migration, 119, 238, 296 Milk and detergent bottles, 161 Millipedes, 90 Mine and quarry fill, 70 mineral resources, viii, 19


Index

335

mineralization, 178, 215, 216, 217, 223, 239 Mineralization, 215 Mining shale, 276 mixing, 157, 170, 240, 305 mobile phone displays, 47 mobile phone screens, 53 model, 15, 34, 35, 51, 53, 141, 142, 149, 194, 266, 267, 271, 273, 284 models, 15, 286 modified Proctor compaction, 280, 281 modulus, 108, 122, 147, 148, 150, 151, 152, 213, 235, 236, 285, 288, 299 modulus of elasticity, 213 moisture, 88, 136, 140, 141, 150, 151, 168, 191, 213, 252, 267, 281 Molecular Characterization, 216 molecular orbital, 102 molecular weight, 212, 213, 215, 216, 218, 233, 312 distribution, 212, 216 molecules, 90, 91, 92, 110, 119, 213, 214, 218, 254, 255, 256 monomers, 111, 167, 171, 218, 255 morphology, 98, 129, 130, 148, 156, 195, 213, 233, 239, 240 mortar, xii, 28, 29, 30, 275, 276, 279, 280, 282, 285, 287, 289, 291 motivation, 138 motor vehicle, 45 moulding, 140, 170 MSW, 12, 209, 210 municipal solid waste, 2, 8, 12, 160, 162, 164, 169, 193, 196, 209, 210, 262, 278 municipal solid waste (MSW), 12, 209 municipal waste, 2, 10, 209, 252 municipalities, 5, 7, 8, 9, 11, 12, 17, 43, 84, 177, 278, 298 mushroom, xii, 227, 228, 231 mushroom wastes, xii, 227, 228

nanofibers, 111, 113, 114, 116, 117, 127, 130, 133, 142, 143, 156, 239, 240, 242, 243, 246 nanofibrous membranes, 243 nanomaterials, 90, 91, 93, 97, 122, 247 nanoparticles, 92, 239, 240 nanostructures, 98, 102, 105 National Climate Change Policy White Paper, (2011), 4 National Environmental Management Waste Act (Act No. 59 of 2008), 86 national income, 261 national policy, 194 national policy action plans, 194 national strategy, 3 National Waste Management Strategy, 5, 278 natural aggregates (NA), viii, 19, 20, 23, 27, 31, 32, 283 natural fillers, 63, 218 natural gas, 9, 16, 79, 90, 167 natural polymers, 235 natural resources, 23, 24, 25, 32, 33, 132, 182, 195, 276 negative effects, 252, 258, 286 Netherlands, 22, 23, 27, 48, 191, 209 Neuron Repair, 240 neutral, 111, 141, 142, 243 new products, ix, 2, 11, 39, 41, 53, 87, 195, 277 nitrogen, 88, 109, 171, 231, 242, 252, 258, 261, 269, 270, 315 North America, 124, 160, 206 Norway, 142 NRF, 33, 57, 196, 289, 301 Nuclear Magnetic Resonance, 216 nuisance, 160 nutrient, 300 nutrients, 75, 87, 88, 190, 254, 255, 260

N

Ocean disposal, 70 oceans, 43, 160, 176 oil, 78, 81, 84, 90, 120, 160, 161, 167, 171, 177, 206, 236, 258, 300, 311, 312, 319 oleic acid, 282 oligomers, 131, 214, 217, 218 open dumping sites, 294 operations, 28, 30, 84, 184, 185, 208, 253

nanocomposites, 98, 99, 101, 121, 128, 129, 157, 176, 225, 235, 236, 243, 246, 299 Nanocomposites Reinforcement, 234 Nanocrystalline cellulose (NCC), 146 nanocrystals, 113, 114, 115, 118, 122, 127, 129, 130, 136, 232, 243, 245, 247

O


336

Index

opportunities, vii, xi, 11, 16, 17, 27, 34, 108, 121, 159, 162, 166, 175, 183, 190, 196, 221, 223, 229, 261, 278 optical fiber, 54 optical properties, 152, 157, 237, 247 optimization, 130, 170, 267 organic chemicals, 84, 312 organic compounds, 36 organic content, 280, 281 organic matter, 76, 252 organic solvents, 171, 232 Organic Waste, v, 83, 84, 85, 87, 90, 104 Organization for Economic Co-operation and Development (OECD), 211 oxidation, 54, 117, 141, 178, 232, 243, 255, 256, 310 oxidative agents, 112 oxidative attack, 214 oxidative biodegradation, 214 oxidative degradation, 172, 214, 215 oxygen, 53, 55, 56, 69, 77, 88, 109, 119, 136, 211, 212, 217, 252 ozone, 112, 252, 269, 270 ozone layer, 269

P Pacific, 139, 155, 207 packaging, 122, 124, 153, 160, 161, 163, 168, 174, 204, 208, 209, 210, 220, 221, 224, 235, 237, 239, 241 Pakistan, 184, 188 palm oil, 183, 199 particle size distribution, 31, 280, 314 pathogens, 2, 8, 78, 253 pavement sub-base material, xii, 275, 280 pavement sub-base materials, xii, 275, 281 paving blocks, xii, 275, 280 pectin, 108, 122, 142 percolation, 236 periodontal, 239, 247 Permanganate treatment, 144 permeability, 36, 283, 288 permission, 10, 114, 116, 161, 233, 237 peroxide, 112, 144, 317 treatment, 144 persistent luminescence, 48, 49, 50, 51 PET, 161, 170, 171, 173, 176, 207, 222 petro based polyester (PCL, PBAT), 214

petroleum, xi, 84, 124, 163, 167, 168, 203, 204, 205, 218, 221, 223, 235 Petroleum, xi, 18, 203, 207, 218 petroleum based plastics, xii, 203, 204, 205, 218 pH, 111, 112, 140, 141, 142, 144, 189, 211, 212, 213, 256, 257, 266, 273, 280, 281, 282, 284, 286 pharmaceutical, 231, 300 Phosphor(s), 47, 48, 49, 51, 53, 54, 55 phosphoryl chitin, 234 photoluminescence, 49, 50, 51, 99 Photovoltaic Solar Cells, 98 physical and mechanical properties, 285 physical properties, xiii, 30, 41, 195, 199, 212, 216, 221, 277, 293 physicochemical characteristics, 189 physicochemical properties, 185, 245 plant growth, 75, 87 plants, viii, 1, 2, 8, 9, 10, 11, 13, 14, 15, 17, 23, 31, 34, 38, 63, 66, 73, 88, 93, 94, 167, 169, 214, 253, 258, 260, 261, 274, 296, 305 Plasma treatment, 144 Plastic bags, 219 Plastic caps, 220 plastic disposal, xi, 159 Plastic fibre insulation, 222 plastic products, 221 Plastic Recycling, 167, 172 plastic waste, 125, 159, 160, 162, 163, 164, 167, 169, 174, 175, 176, 206, 207, 209, 210, 211, 222, 224, 237 Plastics, ix, xi, 21, 23, 27, 62, 79, 92, 133, 159, 160, 163, 164, 166, 167, 168, 169, 171, 172, 173, 174, 175, 176, 177, 178, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 217, 218, 221, 222, 223, 225, 226, 237, 294, 298, 310, 317 production rate, xi, 159 playground equipment, 218, 219, 309 Policies and Regulations, vii, viii, xiii, 1, 2, 3, 7, 8, 13, 16, 20, 24, 27, 33, 63, 64, 108, 125, 177, 207, 260, 275, 277, 297, 298, 301 policy, vii, viii, 1, 2, 3, 4, 7, 10, 18, 35, 64, 103, 163, 174, 183, 224, 231, 260, 277, 278 policy makers, 174, 231 pollutants, 42, 73, 172, 256 pollution, ix, 3, 24, 40, 43, 61, 66, 73, 76, 79, 90, 108, 118, 120, 163, 183, 190, 193, 196, 207, 211, 222, 228, 294, 307 polyamides, 213 polybrominated diphenyl ethers, 63


Index polybutylene terephthalate, 138 polycarbonate (PC), 70, 81 polycarbonate polymer, 70 polyesters, 213, 224 polyethylene (PE), 145, 161, 171, 205, 223, 224, 225 Polyethylene terephthalate (PET), 161 polyethylenes, 140, 151, 223 polyhydroxyalkanoates (PHA) resins, 207 polylactic acid (PLA), 121, 207 polymer, xii, xiii, 43, 65, 69, 79, 81, 103, 108, 121, 122, 123, 124, 127, 140, 143, 145, 152, 157, 160, 162, 163, 165, 169, 171, 172, 173, 179, 185, 205, 207, 210, 211, 212, 213, 214, 215, 217, 223, 224, 227, 234, 235, 242, 243, 246, 248, 254, 299, 303, 304, 314, 315, 316, 317, 318 polymer blends, 304, 318 polymer chain, 214, 254 polymer composite material, 299 polymer composites, 69, 108, 122, 127, 140, 143, 145, 157, 318 Polymer Composites, 69, 82, 123, 128 polymer films, 217 polymer materials, 79, 103, 207, 224 polymer matrices, xiii, 43, 65, 66, 123, 145, 303, 314, 317 polymer matrix, 65, 69, 70, 81, 121, 123, 127, 143, 145, 211, 304, 318 polymer properties, 212 polymer recycling, 162 polymer structure, 211 polymer wastes, 179 polymeric materials, 160, 163, 165, 167, 168, 169, 170, 204, 205, 211, 216, 217, 235, 300 polymeric matrices, 122, 147, 314 polymeric products, 161, 314 polymerization, 113, 147, 236, 244 polyolefins, 140, 151, 206, 214, 320 polypropylene, 77, 80, 82, 92, 122, 124, 132, 138, 139, 145, 148, 151, 152, 155, 157, 169, 171, 176, 177, 178, 205, 207, 299 polypropylene (PP), 77, 92, 122, 124, 138, 139, 145, 148, 152, 155, 157, 161, 171, 176, 205 polypyrrole, 147 polysaccharides, 213, 223, 234, 243, 245, 268 polystyrene, 92, 171, 178, 205 polystyrene (PS), 92, 161, 171, 205 polyurethane, 80, 138, 318 polyvinyl alcohol, 214, 238 Polyvinyl chloride (PVC) , 80, 161, 171, 178

337 population, x, 2, 11, 17, 30, 49, 90, 107, 109, 125, 165, 187, 193, 210, 212, 214, 252, 259, 270, 297 population growth, x, 107, 125, 165 Porcelain Stone tile, 44 pore size distribution, 280, 287 porosity, 28, 29, 46, 88, 147, 184, 189, 192, 238, 239, 281, 283, 288 Portland cement, 74, 183, 191, 192, 197, 201, 283, 287 Portland Cement Concrete, 74 post-consumer polythene waste, 221 potassium, 111, 142, 143, 236, 246, 300 potassium hydroxide, 111, 142, 143 poultry, 109, 259, 260, 270 power generation, 15, 94, 191, 221 power plants, xi, 73, 181, 188, 195, 209 pozzolanic cement, 280 pozzolanic properties, 189 Pr3+, 46, 48, 49, 51 PrCl3, 46, 47 preparation, xii, 90, 94, 130, 132, 140, 141, 144, 176, 200, 227, 229, 231, 233, 236, 242, 243, 286, 299 preservation, 20, 242, 266 pressure homogenizer, 117, 141 prevention, 40, 108, 166, 207, 208, 229, 313 principles, 195, 208, 216, 258, 277 Procotex S. A. Corporation NV, 137 procurement, 2, 3, 34, 260 pro-degradant, 206 producers, 2, 4, 137, 296, 307, 308 production costs, 231, 259 Production of Fly Ash, 66 production technology, 2 project, 6, 10, 27, 36, 43, 127, 190, 284, 288, 301 proliferation, 238, 239, 240, 241 Pro-oxidant, 206 propylene, 145, 157 protection, 108, 257 proteins, 213, 217, 228, 230, 232, 255, 257 Proton exchange membrane (PEM), 241 protons, 241, 256 Psychrophiles, 90 public sector, 12, 188, 231, 278 pulp, 115, 117, 136, 140, 141, 146, 147, 151, 156, 157, 226 pulverized coal, xi, 66, 68, 181, 188 purification, 44, 140, 232 purity, 238, 305 PVA, 80, 122, 236, 238


338

Index

PVC, 80, 161, 170, 171, 172, 176, 177 pyrolysis, 4, 10, 119, 131, 147, 171, 174, 176, 263, 300, 308, 310, 311, 312, 318, 319

Q quantification, 27, 33, 267 quarry dust (QD), 192 quarrying operations, 185

R Radford, 139 radial tire, 306 radiation, 59, 80, 102, 136, 233 radius, 280, 287 rainfall, 259, 261 raw materials, xi, 4, 21, 24, 32, 41, 62, 78, 87, 92, 167, 181, 192, 193, 195, 224, 252, 258, 261, 277, 304, 308 reaction medium, 256 reaction rate, 253, 270 reactions, 23, 46, 171, 185, 213, 255, 256 reactive groups, 234 reactivity, xi, 181 recombination, 99, 103 recommendations, 35, 164 reconstruction, 3, 238 recovery, xi, 8, 17, 41, 87, 109, 111, 113, 159, 162, 163, 164, 165, 166, 167, 169, 171, 172, 173, 175, 177, 189, 194, 195, 196, 208, 209, 210, 229, 230, 231, 307, 308, 309, 312, 313, 318, 319 recreation, 222 Recycle, 41, 195 recycled aggregates (RA), viii, 19, 20, 23, 27, 30, 31, 32, 34, 35, 36, 37, 38, 281, 283, 284 recycled brick, 276, 281, 290 recycled coarse aggregates, 283 recycled concrete aggregate, 31, 32, 35, 37, 38, 280, 281, 289 recycled petroleum based plastics, xi, 203, 205, 223 Recycled plastics, 221 recycling, vi, viii, ix, xi, xii, xiii, 7, 12, 19, 21, 23, 24, 25, 27, 28, 30, 33, 34, 35, 36, 38, 56, 62, 63, 80, 81, 82, 83, 87, 88, 104, 157, 159, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 183, 194, 195, 196, 198, 203, 204, 207, 208, 209, 210, 221, 222, 224,

226, 229, 230, 277, 278, 282, 284, 285, 286, 290, 294, 298, 301, 303, 304, 307, 308, 313, 315, 318, 319, 320 of waste, 87, 207, 308, 318, 320 red, 48, 53, 235, 284, 290 Reduce and Reuse, 168 reduction, xi, 7, 20, 24, 32, 33, 86, 118, 145, 152, 159, 192, 193, 194, 203, 208, 209, 252, 276, 277, 281, 286, 288, 295, 307, 314, 317 reengineering, 204, 205 refuse bags, 161 regeneration, 240, 247 regions of the world, 207, 210 regulations, vii, ix, xi, xiii, 3, 7, 10, 16, 23, 30, 64, 71, 72, 78, 83, 103, 124, 159, 211, 235, 275, 303, 307, 308, 319 regulatory framework, 10 reinforcement, x, 108, 121, 123, 127, 132, 135, 136, 137, 147, 196, 199, 228, 235 remediation, 40, 85, 171 Renewable Energy, 3, 4, 10, 11, 14, 17, 132, 252, 273 Fit in Tariff (REFIT) Phase 2, (2009), 4 Renewable Energy Strategy, (2003), 3 renewable energy technologies, 3 renewable fillers, 235 renewable resources, x, 124, 126, 135, 154, 205, 209 repair, 154, 163, 235, 238, 239, 241 requirements, 10, 16, 24, 64, 121, 173, 182, 191, 257, 258, 262, 273, 280, 307 researchers, vii, ix, x, 14, 39, 64, 68, 91, 108, 135, 136, 154, 165, 173, 193, 204, 241, 252, 261, 262, 265, 268, 271, 284, 287, 299, 300, 312, 317 residues, xi, xii, xiii, 15, 82, 84, 115, 119, 121, 131, 132, 133, 154, 199, 203, 207, 212, 218, 228, 241, 251, 262, 263, 266, 293, 294, 298, 300 resistance, ix, 29, 30, 35, 36, 37, 62, 69, 70, 76, 77, 79, 81, 111, 114, 138, 146, 147, 151, 169, 192, 236, 282, 283, 285, 306 resources, x, 3, 57, 87, 93, 104, 108, 123, 126, 135, 138, 153, 154, 165, 168, 174, 194, 205, 209, 252, 261, 313 response, xi, 182, 208, 240, 242, 267 restrictions, 10, 71, 74 Reuse, viii, 3, 19, 20, 21, 22, 24, 25, 28, 31, 32, 33, 34, 41, 43, 87, 165, 168, 194, 195, 196, 197, 208, 222, 229, 230, 289 re-using waste, 87 revenue, xi, 12, 181, 206, 230, 260, 278


Index rice husk, 75, 156, 183, 197, 199, 200, 294 risk, 10, 16, 23, 30, 63, 78, 269 road accidents, 48 Road Markings, 48 road surfacing, 25 room temperature, 111, 140, 143, 288 rotations, 208, 266 roughness, 29, 111, 123, 127 routes, 90, 175, 209, 271 rubber, xiii, 69, 80, 81, 145, 170, 183, 192, 198, 201, 214, 222, 226, 235, 243, 246, 299, 303, 304, 305, 306, 309, 310, 311, 312, 314, 315, 317, 318, 319, 320 rural areas, 15, 17, 85, 139, 261 rye husk, 147, 148, 155

S safety, 9, 63, 124, 252 sawdust, 84, 148, 152, 169, 177, 295 sawmills waste, 153, 155 science, ix, 62, 72, 77, 104, 136, 176, 242 Scientists and environmentalists, 230 sea shells, ix, 39, 41, 42, 43, 44, 56 seafood, 236, 242 second generation, 131, 272 Self glowing road lines, 48 SEM micrographs, 148, 149, 150 sensitivity, 150, 269, 281 sewage, 2, 8, 11, 13, 210, 252, 253 shear, 31, 36, 116, 117, 199, 246, 281 shear strength, 36, 199, 281 shortage, viii, 19, 20, 32, 120, 184 showing, 47, 54, 67, 101, 148, 150, 161, 186, 233, 237 shrimp, 228, 230, 231, 232, 242, 243 side effects, 84, 85, 89, 182 silage effluent, 84, 294 Silane, 123, 144, 145, 151 treatment, 144 silica, 56, 62, 80, 183, 185, 189, 192, 285, 295 silica fume, 183, 192 single-layered graphene, 92 SiO2, 65, 188, 286, 288, 291 Landfill, xi, xiii, 9, 20, 24, 71, 76, 77, 79, 87, 125, 159, 160, 162, 163, 165, 174, 182, 194, 203, 204, 205, 209, 210, 230, 252, 253, 276, 288, 298, 303, 304, 307

339 sludge, 2, 8, 11, 94, 199, 200, 210, 253, 257, 294 social responsibility, 308 society, viii, 19, 20, 33, 179, 261 sodium hydroxide, 31, 117, 143, 144, 231, 261, 264, 284 Softwood, vi, x, 135, 136, 140, 141, 145, 146, 147, 148, 149, 151, 152, 153, 154, 155, 157 pulp, 141 Soil, ix, 22, 74, 75, 78, 81, 83, 84, 85, 87, 88, 89, 103, 104, 109, 190, 195, 197, 199, 200, 201, 204, 217, 218, 226, 258, 267, 294, 296, 300 Fertilizers, 87 Improvement, 75 soil erosion, 258 solar cells, 94, 102 solar efficiency, x, 83 solid waste, xi, 2, 4, 7, 8, 12, 13, 15, 20, 21, 32, 33, 160, 162, 164, 165, 169, 171, 175, 177, 178, 181, 183, 193, 196, 200, 202, 209, 210, 211, 224, 255, 262, 276, 278 solution, xi, 16, 20, 28, 33, 93, 119, 140, 143, 144, 151, 164, 181, 183, 185, 193, 196, 232, 233, 234, 235, 236, 240, 258, 264, 266, 282, 284, 290, 291 solvents, 84, 208, 232, 234, 235 South Africa, vii, viii, ix, x, xiii, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 16, 17, 19, 33, 39, 40, 43, 48, 49, 56, 57, 61, 66, 68, 83, 84, 85, 86, 94, 103, 104, 107, 108, 109, 118, 119, 125, 135, 139, 159, 160, 163, 164, 165, 166, 173, 174, 175, 176, 181, 190, 194, 196, 202, 203, 226, 227, 229, 251, 258, 259, 260, 270, 275, 277, 278, 289, 293, 296, 297, 298, 301, 303, 307, 308, 319 Sowbugs, 90 species, 54, 56, 76, 94, 112, 171, 216, 228, 232, 268, 282, 295, 304, 307 specific gravity, 28, 31 specific surface, 148, 152, 243, 284 specifications, 173, 280, 281 Spectroscopy, 54, 56, 98, 216 Spiders, 90 spontaneous luminescence, 49 stability, 144, 152, 236, 261, 266, 273 Stabilized Base Course, 74 stabilizers, 170, 186, 199, 283 stakeholders, 9, 20, 33, 86, 162, 164, 165, 174 starch, 109, 120, 133, 142, 145, 156, 207, 214, 235, 245 state, 5, 8, 25, 54, 56, 99, 117, 131, 150, 167, 174, 198, 224, 262, 272, 276, 277, 280, 281


340

Index

static triaxial, 280 statistics, 20, 48, 49, 79, 261 steam-explosion technique, 148, 152 Stearic acid treatment, 143 steel, 34, 95, 103, 125, 191, 305, 306, 312, 314 stem cells, 240 Stemergy, Crailar and LLC, 137 stimulated luminescence, 49 storage, x, 15, 73, 83, 94, 96, 97, 98, 103, 125, 147, 220, 241, 266, 294, 298, 308 structural changes, 215, 216 Structural Fills/Embankments, 74 structure, 12, 15, 21, 65, 69, 70, 76, 97, 98, 102, 103, 109, 110, 112, 113, 122, 126, 140, 147, 185, 192, 201, 204, 212, 214, 228, 229, 234, 238, 239, 240, 276, 288, 317 structure of chitin, 228 styrene, 69, 81, 145, 170, 171, 306, 312 styrene-butadiene rubber, 306 substitution, 23, 124, 283, 285, 288 substrate, xii, 156, 213, 216, 217, 251, 254, 255, 256, 257, 266, 267, 269, 270, 273 substrates, 216, 217, 238, 247, 253, 255, 256, 265, 269 sugarcane bagasse, xi, xiii, 108, 183, 197, 199, 200, 203, 207, 293, 299, 300 sulphur, 252, 306, 310, 311 Sun, 93, 105, 214, 245, 273, 290, 291, 302 sunlight, 51, 226 supply chain, 35, 163, 165 surface area, 95, 122, 123, 127, 147, 189, 212, 238, 240, 243, 284, 312, 315 surface energy, 148, 152 surface impoundment, 70, 71 surface modification, 122, 123, 132, 156, 235 sustainability, 35, 122, 175, 207, 221, 223, 266 sustainable construction materials, 32, 34, 182, 196, 197 sustainable development, 23, 32, 40, 182, 193, 195, 196 Sustainable Development, 43, 193 sustainable energy, 93, 252, 319 sustainable growth, xii, 203, 286 Sweden, viii, 2, 14, 16, 22, 269 swelling, 238, 239, 243 synthesis, xiii, 56, 90, 91, 92, 94, 178, 185, 189, 244, 254, 293 synthetic gas, 87 synthetic polymers, 175, 204

T Ta2O5, 46, 47 Tanzania, 30, 38, 164 target, 3, 4, 125, 166, 282 TDI treatment, 144 Technaro GmbH, 124, 137 techniques, xiii, 73, 91, 92, 117, 128, 144, 168, 169, 182, 225, 293, 294, 319 technological advancement, 182, 195 technological innovations, 193 Technologies, 1, 15, 17, 34, 81, 105, 137, 199, 200 technology, viii, xii, 2, 7, 10, 13, 14, 15, 16, 17, 49, 73, 94, 118, 120, 127, 166, 185, 191, 205, 208, 221, 223, 224, 251, 258, 260, 263, 274, 319 telecommunications, xi, 159 television, 47, 48, 53, 54 screens, 53 temperature, ix, 4, 47, 51, 53, 62, 64, 69, 77, 79, 90, 110, 111, 115, 122, 140, 141, 142, 143, 149, 171, 183, 185, 191, 192, 211, 212, 216, 241, 253, 257, 268, 282, 284, 286, 288, 308, 312, 314 tensile strength, 31, 122, 123, 140, 147, 149, 150, 151, 152, 216, 235, 280, 285, 287, 288, 299 testing, 142, 200, 211, 224, 271, 281, 285 TGA, 112, 128, 216 that new concepts, 136 The Integrated Resource Plan, (2011), 4 The Licensing Requirement of the Waste Water Treatment Works (WWTW), 5 The National Development Plan, 4 The National Organic Waste Composting Strategy (NOWCS), 84, 86 The National Waste Management Strategy (NWMS), (2012), 5 thermal aging, 226 Thermal Analysis, 216, 246 thermal conductivity, 80, 192, 281 thermal degradation, 128, 178 thermal energy, ix, 49, 83, 103 thermal power plants, xi, 181, 188 thermal properties, 122, 128, 173, 184, 198, 236, 284 thermal resistance, 77, 79 thermal stability, 76, 113, 123, 130, 146, 147, 148, 152, 190, 236 Thermal stimulation, 51 thermal treatment, 4, 294, 319 thermodynamic parameters, 286


Index thermogravimetric analysis, 112, 156, 216 thermoluminescence, 49, 59 thermoluminescence spectra, 49 Thermophiles, 90 thermoplastic polyurethane, 80 thermoplastics, 147, 315, 316, 317, 318, 319 thermosets, 173, 315, 318, 319 tiles, 27, 46, 56, 221, 222 TiO2, 46, 47, 56, 172, 179 tissue, 85, 228, 234, 235, 238, 239, 240, 247 tissue engineering, 234, 235, 238, 239, 240, 247 titanium, 62, 170 top-down, 90, 91, 92 total energy, 14, 126, 163 toxicity, 30, 41, 62, 63, 80, 86, 182, 195, 218, 229, 238, 240, 269, 277 training, 9, 166, 174, 308 transport, 16, 30, 81, 85, 194, 267 transportation, xi, 14, 62, 137, 159, 172, 182, 231, 241, 294, 318 treatment, 4, 11, 13, 15, 17, 21, 23, 62, 94, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 123, 126, 127, 129, 130, 133, 142, 143, 144, 145, 148, 151, 152, 157, 162, 163, 185, 189, 191, 194, 195, 200, 228, 231, 232, 234, 236, 241, 245, 246, 261,262, 264, 267, 272, 273, 277, 284, 294, 298, 310, 319 treatment methods, 110, 113, 118, 127, 145 triplet state, 99 t-shirts, 219, 220

U Ultimate biodegradation, 215 Ultrasonication process, 142 ultrasound, 233 unemployment rate, 2 Unfired Bricks, 186, 199 United Kingdom (UK), 20, 21, 22, 23, 27, 30, 35, 36, 71, 72, 104, 105, 168, 188, 191, 231 United Nations, 43, 226 United Nations world summit on Sustainable Development, 43 United States of America (USA/US), 15, 18, 20, 23, 27, 58, 59, 70, 79, 109, 124, 137, 160, 209, 220, 221, 296, 306, 307 University of South Africa, 39, 61, 83, 94, 303 University of the Free State, 57, 59, 61, 94

341 upholstery, 153 urban, 7, 11, 32, 166, 173, 186, 265 urban areas, 173 urban paved roads, 32 urbanization, 2, 11, 20, 21, 30, 32, 165, 187, 193, 259, 297 urethane, 222, 235, 245 utilized lime powder (LP), 191 UV radiation, 212

V vacuum, 103, 142, 300 Vacuum filtration, 142 vacuum pump, 142 valorization, xiii, 293 variations, 228, 269 varieties, 264, 268 vegetation, 92, 94, 254 vehicles, xiii, 14, 46, 163, 303 velocity, 140, 170, 315 viscosity, 113, 311 vision, 20, 166, 207

W Waste, v, vi, vii, viii, ix, x, xi, xii, xiii, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 56, 57, 58, 61, 62, 64, 65, 66, 69, 70, 71, 72, 73, 75,76, 77, 78, 79, 82, 83, 84, 85, 86, 87, 88, 89, 90, 92, 93, 94, 103, 104, 107, 108, 109, 121, 125, 132, 135, 155, 159, 160, 162, 163, 164, 165, 166, 167, 168, 169, 171, 172, 173, 174, 175, 176, 177, 178, 179, 181, 182, 183, 184, 185, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 204, 207, 208, 209, 210, 211, 214, 221, 222, 223, 224, 226, 227, 228, 229, 230, 231, 232, 234, 236, 242, 251, 252, 253, 255, 257, 258, 259, 260, 261, 262, 265, 270, 271, 272, 274, 275, 276, 277, 278, 279, 280, 282, 283, 284, 286, 287, 288, 289, 290, 291, 293, 294, 295, 297, 298, 299, 300, 301, 302, 303, 304, 307, 308, 310, 311, 312, 313, 314, 315, 317, 318, 319, 320 and Energy, 3 avoidance and Reduction, 41


342

Index

Brick, xii, 275, 276, 277, 279, 280, 282, 283, 286, 287, 288, 289, 290 Cookie, 92 Management, viii, ix, x, xi, xiii, 1, 2, 3, 4, 5, 7, 8, 9, 12, 16, 20, 21, 24, 26, 27, 33, 34, 38, 40, 41, 56, 57, 61, 62, 77, 79, 86, 87, 104, 107, 108, 125, 159, 160, 162, 164, 165, 173, 174, 176, 177, 179, 181, 194, 195, 196, 197, 207, 209, 211, 224, 227, 229, 230, 276, 277, 278, 293, 294, 295, 297, 298, 303, 304, 308 Hierarchy, 6, 41, 165, 230, 278 strategies, 20, 26, 27, 108, 162, 164, 174, 175, 207, 229 Materials, x, xiii, 22, 24, 40, 62, 64, 72, 75, 76, 92, 107, 125, 165, 169, 175, 183, 184, 185, 190, 194, 198, 202, 208, 228, 286, 289, 293, 294, 300, 318 shell, 43, 44, 230, 231 waste disposal, 7, 16, 20, 70, 72, 79, 87, 108, 166, 207, 294, 295, 307 Waste Management, vi, 4, 6, 24, 34, 35, 36, 37, 38, 70, 86, 88, 175, 176, 177, 178, 194, 198, 201, 202, 207, 274, 289, 290, 293, 297, 301, 319, 320 waste treatment, 4, 10, 12, 13, 24, 71, 163, 174 wastewater treatment, 236 plants, 15, 94 Water, ix, 11, 13, 17, 22, 24, 28, 29, 31, 32, 46, 57, 71, 74, 75, 83, 88, 89, 90, 93, 103, 104, 111, 115, 118, 119, 125, 129, 140, 141, 142, 143, 144, 147, 149, 163, 169, 172, 182, 189, 190, 191, 192, 193, 195, 199, 200, 201, 212, 213, 214, 215, 217, 220, 221,223, 230, 231, 232, 234, 236, 238, 240, 241, 243, 244, 255, 257, 258, 265, 267, 280, 281, 282, 283, 286, 287, 288, 294, 304, 314

absorption, 28, 29, 31, 32, 46, 144, 149, 190, 191, 192, 199, 280, 281, 283, 286 for showering, ix, 83 use, 182, 193 water absorption, 28, 29, 31, 32, 46, 144, 149, 190, 191, 192, 199, 280, 281, 283, 286 water permeability, 283 water purification, 236, 243 wheat husk, 147, 148, 155 White Paper on Integrated Pollution and Waste Management, (2000), 3 wildlife, 58, 160, 167 windows, 161, 221 Witwatersrand University, 94 wood, x, 21, 23, 27, 80, 89, 94, 133, 135, 136, 139, 142, 143, 145, 146, 147, 149, 151, 152, 153, 154, 155, 156, 157, 170, 209, 226, 255, 294 plastic composites, 151 products, 154 -polymer composites (WPC), 140 wool, 151, 157 workers, 63, 77, 120, 252, 258, 264, 306, 311 worldwide, viii, xi, xii, 19, 20, 24, 32, 65, 72, 120, 127, 153, 159, 160, 174, 182, 185, 189, 194, 204, 207, 251, 275 Wound Dressing, 240 wound healing, 234, 240, 244

Y yield, xii, 112, 118, 119, 120, 121, 127, 130, 132, 136, 212, 251, 254, 257, 262, 263, 264, 267, 268, 269, 270, 272, 273, 300, 305


View publication stats