Many thanks and gratitude to my supervisors; Dr. Hafez Q. Shaheen and. Dr. Shehdeh W. ...... (Temdrara et al., 2011), commercial activated carbon (Qadeer, 1998), ...... Bouchelta, Chafia; Medjram, Mohammed Salah; Zoubida, Marsa Chekkat,.
An-Najah National University Faculty of Graduate Studies
Removal of Polyphenols from Olive Mill Wastewater using Activated Olive Stones
By
Ruba Abdelrahman Farid Aladham
Supervisor
Dr. Hafez Q. Shaheen Co-Supervisor
Dr. Shehdeh W. Jodeh
This Thesis is Submitted in Partial Fulfillment of the Requirements for the Degree of Master in Water and Environmental Engineering, Faculty of Graduate Studies, An-Najah National University, Nablus, Palestine. 2012
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Dedication This work is dedicated to those who believe in and support applied scientific research individually and collaboratively in Palestine. To my parents and family; for their endless support, love, encouragement and understanding. To my husband, for his empowerment driving force, care, and unconditional support.
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Acknowledgement Many thanks and gratitude to my supervisors; Dr. Hafez Q. Shaheen and Dr. Shehdeh W. Jodeh for their academic, technical guidance and full support during thesis work. I'm grateful for Palestinian Water Authority (PWA) along with the Austrian Development Cooperation (ADC) for their financial, technical and logistic support to bring this research to light. I appreciate the warm host, facilitation and cooperation of the technical and management staff at Water and Environmental Studies Institute Laboratory, Poison Control Chemical/ Biological Analysis Center and Chemistry Department at An-Najah National University during the experimental and analysis work. I owe my deepest gratitude to my family; they enlightened my academic path with care and support.
v
@?ارAا :ﺃﻨﺎ ﺍﻝﻤﻭﻗﻌﺔ ﺃﺩﻨﺎﻩ ﻤﻘﺩﻤﺔ ﺍﻝﺭﺴﺎﻝﺔ ﺍﻝﺘﻲ ﺘﺤﻤل ﺍﻝﻌﻨﻭﺍﻥ
Removal of Polyphenol from Olive Mill Wastewater using Activated Olive Stones
?KGLMC BJدGLC اOGPMC اQJ لSTPUCت اGH?آJ BCإزا bcTMCن اSY^_Cى اSa امWXYZ[\ نSY^_Cا ﺒﺎﺴﺘﺜﻨﺎﺀ ﻤﺎ ﺘﻤﺕ،ﺃﻗﺭ ﺒﺄﻥ ﻤﺎ ﺍﺸﺘﻤﻠﺕ ﻋﻠﻴﻪ ﻫﺫﻩ ﺍﻝﺭﺴﺎﻝﺔ ﺇﻨﻤﺎ ﻫﻲ ﻨﺘﺎﺝ ﺠﻬﺩﻱ ﺍﻝﺨﺎﺹ ﺃﻭ ﺃﻱ ﺠﺯﺀ ﻤﻨﻬﺎ ﻝﻡ ﻴﻘﺩﻡ ﻝﻨﻴل ﺃﻴﺔ ﺩﺭﺠﺔ ﺃﻭ ﻝﻘﺏ، ﻭﺃﻥ ﻫﺫﻩ ﺍﻝﺭﺴﺎﻝﺔ ﻜﻜل،ﺍﻹﺸﺎﺭﺓ ﺇﻝﻴﻪ ﺤﻴﺜﻤﺎ ﻭﺭﺩ .ﻋﻠﻤﻲ ﺃﻭ ﺒﺤﺜﻲ ﻝﺩﻯ ﺃﻴﺔ ﻤﺅﺴﺴﺔ ﺘﻌﻠﻴﻤﻴﺔ ﺃﻭ ﺒﺤﺜﻴﺔ ﺃﺨﺭﻯ
Declaration The work provided in this thesis, unless otherwise referenced, is the researcher's own work, and has not been submitted elsewhere for any other degree or qualification.
Student Name:
:BHCGdC اeZإ
Signature:
:fP@SYCا
Date:
:g^رGYCا
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Abbreviations ACE: Army Corps of Engineers AOLS: Activated Olive Stones BET: Brunauer-Emmett-Teller BJH: Barret Joyner and Halenda BOD5: 5-days Biochemical Oxygen Demand COD: Chemical Oxygen Demand FAO: Food and Agricultural Organization IOC: International Olive Council MEnA: Ministry of Environmental Affair MoA: Ministry of Agriculture MTZ: Mass Transfer Zone OLH: Olive Husk OLS: Olive Stones OMWW: Olive Mill Wastewater PCBS: Palestinian Center Bureau of Statistics PWA: Palestinian Water Authority TDS: Total Dissolved Solids TS: Total Solids TSS: Total Suspended Solids
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Notations n: Sample size with finite population N: Population size of olive mills Z: Z statistic for a level of confidence P: Expected proportion d: precision
and : null and alternative hypotheses, respectively
: Production capacity mean for olive mills surveyed in this research
: Production capacity mean for olive mills surveyed by PMA
: Critical value for t student distribution
: Level of significance t: T-test statistics value
P/P0: Relative equilibrium pressure q1: Heat of adsorption of the first layer q2: Heat of adsorption of the second and subsequent layers
: Specific BET surface area : Avogadro's number
: Molar volume of the gas
Vm: Volume adsorbed at the monolayer capacity
: Change in the adsorption volume of the liquid adsorbate
: Change in the thickness of the layer adsorbed for the considered stage of desorption : Average pore diameter
: Average Kelvin radius of the space between adsorbed layers
: Change in the volume of empty pore for the n-stage of desorption
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: Equilibrium adsorption capacity in batch system
: Maximum adsorption capacity in batch system : Equilibrium concentration of the adsorbate
: Initial solution concentration KL: Langmuir constant
!" Freundlich relative adsorption capacity constant qt : Adsorption capacity at time t
k1: Pseudo-first-order rate constant V0: Initial adsorption rate Vp: Volume of the particle
: Average solute concentration in the solid As: Surface area of the particle
k2: Pseudo second order rate constant kf: Film mass transfer coefficient R': Liquid film diffusion constant De: Effective liquid film diffusion coefficient r0: radius of adsorbent beads ∆r0: Thickness of liquid film k′: Equilibrium constant of adsorption
: Initial solute concentration fed to fixed bed
Ct : adsorbate concentration in the fluid phase at time t # : Solute flow rate
$ : Superficial velocity
%& : Diffusion coefficient through the mobile phase
': Void fraction of the bed
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(: Interstitial velocity of the carrier fluid
t: Operating time
Z: Distance from the inlet of the mobile phase H: Bed depth
& : Pollutant concentration in the mobile phase
!) : Overall volumetric coefficient kTh: Thomas rate constant
!*+ : Yoon and Nelson rate constant
kBA : Bohart and Adam rate constant Q: Fluid volumetric flow rate q0: Maximum adsorption capacity
( : Liquid migration rate through the bed
,- : Kinetic coefficient of the external mass transfer
Ms: Amount of total solute adsorbed up to saturation
Mtotal: total amount of phenol sent to the fixed bed
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Table of Contents No.
1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.7.1 1.7.2 1.8 1.8.1 1.8.2 1.8.3 1.8.4 2 2.1 2.2 2.2.1 2.2.2 2.2.2.1 2.2.2.2 2.2.3 2.2.4 2.2.5 2.2.5.1 2.2.5.2
Content Dedication Acknowledgement Declaration Abbreviations Notations Table of Contents List of Tables List of Figures List of Appendices Abstract Chapter 1: Introduction General background Problem description Palestinian researches on OMWW management and treatment Phenol detoxification from OMWW Research hypothesis Research objectives Study area Olive oil extraction in the study area Quesionnaire sample size Methodology Olive mill survey and samples collection Production of activated carbon from olive stones Total phenol batch adsorption Fixed bed adsorption of total phenol onto activated olive stones Chapter 2: Olive Mills State of Art Survey Introduction Background Olive oil production in Palestine and Worldwide Olive oil production systems Traditional pressing process Centrifugation Three-phase centrifugal extraction products Environmental impact of OMWW Treatment of olive mill wastewater Thermal processes Physio-chemical processes
Page iii iv v vi vii x xv xvii xix xx 1 1 1 3 4 5 5 6 7 8 8 9 9 10 10 12 12 12 12 15 15 16 18 18 21 21 23
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No. 2.2.5.3 2.3. 2.3.1 2.3.1.1 2.3.1.2 2.3.1.3 2.3.1.4 2.3.1.5 2.3.1.6 2.3.1.7 2.3.1.8 2.3.2 2.4 3 3.1 3.2 3.2.1. 3.2.2 3.2.3 3.3 3.3.1 3.3.2 3.4 3.4.1 3.4.2 3.4.3 3.5 4 4.1 4.2 4.2.1 4.2.2 4.2.2.1 4.2.2.2 4.2.2.3 4.2.3 4.2.3.1
Content
Page Biological treatment 25 Olive mills state of art survey 26 Survey results 27 General findings 27 Extraction season 27 Degree of automation and production capacity 28 Process water consumption 30 Olive mill wastewater generation 33 Management of OMWW 35 Quantities of olive husk 35 Three-phase olive oil extraction mass balance 36 Statistics reliability 37 Conclusions 40 41 Chapter 3: Characteristics of Olive Mill Wastewater Introduction 41 Characteristics of olive fruit and olive oil extraction by 41 products Olive fruit 41 Olive mill wastewater 42 Olive husk 48 Olive mill wastewater characterization in the study area 49 Samples collection and preservation 49 Olive mill wastewater samples analysis 49 Results and discussion 50 General characteristics of OMWW in the study area 50 OMWW pollution load 53 OMWW and wastewater discharge standards in 53 Palestine Conclusions 55 56 Chapter 4: Production and Characterization of Activated Olive Stones Introduction 56 Background 57 Activated carbon 57 Low cost materials for activated carbon preparation 58 Conventional waste (Agricultural) 58 Non-conventional waste (Municipal and Industrial) 58 Naturally occurring adsorbents 60 Production of activated carbon 60 Physical activation 60
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No. 4.2.3.2 4.2.3.3 4.2.4 4.2.4.1
Content
Chemical activation Parameters affecting carbonization/activation process Characteristics of activated carbon Surface characteristics and chemistry of activated carbon 4.3 Experimental set-up 4.3.1 Production of activated olive stones (AOLS) 4.3.1.1 Olive stones preparation 4.3.1.2 KOH impregnation of OLS 4.3.1.3 OLS carbonization and activation 4.3.1.4 ALOS acid/ water washing 4.4 Results and discussion 4.4.1 Effect of activation temperature 4.4.2 Particle size distribution of OLS 4.4.3 Effect of KOH impregnation ratio 4.4.4 Textural characteristics of AOLS 4.4.4.1 Scan electron microscopy 4.4.4.2 Surface area of AOLS 4.4.4.3 Pore size distribution 4.5 Conclusions 5 Chapter 5 : Batch Adsorption of Total Phenol onto Activated Olive Stones 5.1 Introduction 5.2 Background 5.2.1 Adsorption definition 5.2.2 Adsorption mechanism 5.2.3 Factors affecting adsorption equilibrium 5.2.4 Adsorption of phenol 5.2.5 Activated olive stones (AOLS) as an adsorbent 5.2.6 Phenol adsorption mechanism 5.2.7 Effect of OMWW pH on total phenol adsorption capacity 5.2.8 Effect of temperature on total phenol adsorption onto AOLS 5.2.9 Adsorption equilibrium 5.2.10 Adsorption equilibrium models 5.2.10.1 Langmuir adsorption isotherm 5.2.10.2 Freundlich adsorption isotherm 5.2.11 Adsorption kinetics 5.2.11.1 Adsorption reaction models
Page 61 63 65 67 73 73 74 74 75 75 76 76 77 77 79 79 81 83 84 86 86 87 87 87 88 89 90 91 92 93 94 94 95 96 97 97
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No. 5.2.11.2 5.3 5.3.1 5.3.2 5.3.3 5.4 5.4.1 5.4.2 5.4.3 5.4.3.1 5.4.3.2 5.5 6 6.1 6.2 6.2.1 6.2.2 6.2.3 6.2.4 6.2.4.1 6.2.4.2 6.2.4.3 6.2.4.4 6.2.5 6.2.6 6.2.7 6.2.7.1 6.2.7.2 6.2.7.3 6.2.7.4 6.3 6.4 6.4.1 6.4.1.1 6.4.1.2 6.4.1.3 6.4.2 6.4.3 6.4.3.1
Content Adsorption diffusion models Batch adsorption experimental set-up Effect of adsorbent dose Adsorption isotherm (equilibrium) study Adsorption kinetics Results and discussion Effect of adsorbent dose Total phenol adsorption equilibrium modeling Adsorption kinetics of total phenol onto AOLS Reaction kinetic modeling of total phenol onto AOLS Diffusion modeling of total phenol onto AOLS Conclusions Chapter 6: Fixed Bed Adsorption of Total Phenol onto AOLS Introduction Background Mini-column fixed bed adsorption Breakthrough curve and breakthrough point Mass transfer zone in fixed bed Factors affecting performance of fixed bed adsorption Adsorbent particle size Bed depth Flow rate Operational considerations Mini-column studies of phenol adsorption Mass transfer rate in fixed bed Fixed bed breakthrough curve prediction Thomas model Bohart and Adams model Wolbroska model Yoon and Nelson model Fixed bed experimental set-up Results and discussion Experimental breakthrough curve Saturation capacity of AOLS fixed bed Empty bed contact time Breakthrough point Fixed bed performance modeling Full-scale fixed bed configuration design Full-scale fixed bed particle size
Page 99 101 101 102 102 102 102 103 106 107 110 112 113 113 114 114 115 116 117 117 118 118 118 119 120 121 122 122 123 123 124 126 126 127 129 129 130 135 136
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No. 6.4.3.2 6.4.3.3 6.5
Content Full-scale fixed bed depth Full-scale fixed bed diameter Conclusions Recommendations References Appendices kXlMCا
Page 137 139 140 142 144 184 ب
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List of Tables No. Table (1.1) Table (1.2) Table (1.3)
Table Main olive cultivar in the study area Olive mills distribution in northern West Bank Spatial distribution of sample size Summary of three-phase olive mills work Table (2.1) schedule Table (2.2) Production capacity and olive oil yield Table (2.3) Water resources in olive oil extraction facilities Three-phase extraction process water Table (2.4) consumption mass balance OMWW generation rate from three-phase Table (2.5) extraction process Total volume of OMWW generated in the study Table (2.6) area during 2010 olive season Volume of OMWW generated in Palestine during Table (2.7) 2010 olive season Estimated olive husk generated in the study area Table (2.8) during 2010 olive season Quantities of olive husk generated in Palestine Table (2.9) during 2010 olive season Statistical variables for MoA data and this Table (2.10) research samples Table (3.1) Chemical composition of olive fruit Table (3.2) Chemical and physical characteristics of phenol Concentration of cations and anions in OMWW Table (3.3) from three-phase extraction process Table (3.4) General characteristics of olive mill wastewater Table (3.5) Characteristics of olive cake (olive husk) General characteristics of three-phase OMWW in Table (3.6) the study area Correlation between total phenol , TS and COD in Table (3.7) three-phase OMWW in the study area , 2010 Characteristics of OMWW in Palestine presented Table (3.8) by different authors Three-phase OMWW population equivalence in Table (3.9) the study areas (olive season 2010) Characteristics of OMWW with reference to Table (3.10) Palestinian standards for wastewater discharge Activated carbon prepared from conventional Table (4.1) wastes
Page 7 7 8 28 28 30 31 33 34 34 36 36 39 42 34 46 47 48 51 52 53 53 54 59
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No. Table (4.2) Table (4.3) Table (4.4) Table (4.5) Table (4.6) Table (4.7) Table (5.1) Table (5.2) Table (5.3) Table(5.4) Table(5.5) Table (5.6) Table (5.7) Table (6.1) Table (6.2) Table (6.3) Table (6.4) Table (6.5) Table (6.6) Table (6.7) Table (6.8)
Table IUPAC pore classification for porous materials Carbonization/ activation program set-up OLS particle size distribution AOLS yield (w%) for various KOH impregnation ratios BET surface area of AOLS reported in literature General structural characteristics of AOLS Characteristics of chemisorptions and physical adsorption Activated carbon adsorbents from agricultural solid waste Isotherms constant for total phenol adsorption onto AOLS Langmuir separation factor for total phenol adsorption isotherm Reaction models parameters of total phenol adsorption onto AOLS Pseudo-second order parameters of phenol adsorption onto various adorbents Diffusion models parameter of total phenol adsorption onto AOLS Standard specifications of HPMC Typical adsorbents particle size in fixed bed Operational parameters of AOLS fixed bed Fixed bed performance parameters at different breakthrough points Empirical models parameters of total phenol adsorption in AOLS fixed bed Bohart-Adams and Thomas models parameters (prior and beyond inflection point) Typical design values for activated carbon contactors Full-scale fixed bed and mini-column operational parameters
Page 66 75 77 77 82 84 88 90 106 106 108 109 110 115 117 125 129 133 135 136 137
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List of Figures No. Fig (1.1) Fig (1.2) Fig (2.1) Fig (2.2) Fig (2.3) Fig (2.4) Fig (2.5) Fig (2.6) Fig (2.7) Fig (2.8) Fig (2.9) Fig (2.10) Fig (3.1) Fig (4.1) Fig (4.2) Fig (4.3) Fig (4.4) Fig (4.5) Fig (4.6) Fig (4.7) Fig (4.8) Fig (4.9) Fig (4.10) Fig (5.1) Fig (5.2) Fig (5.3) Fig (5.4)
Figure Study area delineation Research methodology Contribution of Mediterranean countries in olive oil production Olive fruit cultivation areas and olive mills distribution in West Bank Quantities of olives pressed and extracted olive oil in Palestine (2003-2010) Traditional pressing process for olive oil extraction Three-phase centrifugal extraction of olive oil Two-phase centrifugal extraction of olive oil Relation between quantity of pressed olives and quantity of olive oil produced in the study area Relation between washing water consumption and olive oil production capacity in each governorate (Full-automatic) Relation between decanter water consumption and olive oil production capacity in each governorate Three-phase olive oil extraction process in Northern West Bank, 2010 Most common phenolic compounds in OMWW Graphite structure Macropores, mesopores and micropores regions in activated carbon AOLS production flow diagram Thermogravimetric analysis curve of OLS Effect of KOH impregnation ratio on acetic acid removal onto AOLS SEM micrographs of AOLS Adsorption isotherm of N2 at 77K onto AOLS Typical adsorption and hysteresis loops defined by IUPAC Pore size distribution of AOLS t-plot of N2 adsorption isotherm onto AOLS Effect of temperature on phenol adsorption from aqueous solutions Effect of AOLS dose on total phenol removal efficiency Effect of initial total phenol concentration on adsorption onto AOLS Equilibrium adsorption isotherm of total phenol
Page 6 11 13 14 15 16 17 17 29 32 32 37 45 66 66 73 76 78 80 81 82 83 84 93 103 104 104
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No. Fig (5.5) Fig (5.6) Fig (5.7) Fig (5.8) Fig (5.9) Fig (5.10) Fig (5.11) Fig (5.12) Fig (5.13) Fig (5.14) Fig (6.1) Fig (6.2) Fig (6.3) Fig (6.4) Fig (6.5) Fig (6.6) Fig (6.7) Fig (6.8) Fig (6.9) Fig (6.10) Fig (6.11) Fig (6.12) Fig (6.13)
Figure Page Freundlich adsorption isotherm of total phenol 105 Langmuir adsorption isotherm of total phenol 105 Effect of contact time on total phenol removal 107 efficiency Pseudo- first order kinetic modeling of total phenol 108 adsorption onto AOLS Pseudo- second order kinetic modeling of total 109 phenol adsorption onto AOLS Second order kinetic modeling of total phenol 109 adsorption onto AOLS Liquid film diffusion modeling of total phenol 110 adsorption onto AOLS Intra-particle (Weber-Morris) diffusion modeling of 111 total phenol adsorption onto AOLS Intra-particle (Dumwald Wagner) diffusion modeling 111 of total phenol adsorption onto AOLS Double exponential diffusion modeling of total 111 phenol adsorption onto AOLS Mass transfer zone and breakthrough curve in fixed 116 bed adsorption AOLS fixed bed adsorption experimental set -up 125 Experimental break through curve of total phenol 126 adsorption onto AOLS fixed bed Saturation capacity of total phenol adsorption onto 128 AOLS fixed bed Fixed bed adsorption modeling (Thomas Model) 131 Fixed bed adsorption modeling (Wolborska Model) 131 Fixed bed adsorption modeling(Yoon-NelsonModel) 131 Fixed bed adsorption modeling (Bohart-Adams 132 Model) Fixed bed adsorption modeling prior and after 133 inflection point (Thomas) Fixed bed adsorption modeling prior and after 134 inflection point (Wolborska) Fixed bed adsorption modeling prior and after 134 inflection point (Bohart-Adams) Total fixed bed depth and number of columns for 138 variable service time Fixed bed diameter for variable flow rate 139
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List of Appendices No. Appendix (A) Appendix (A.1) Appendix (A.2) Appendix (A.3) Appendix (B) Appendix (B.1) Appendix (C) Appendix (C.1) Appendix (C.2) Appendix (C.3)
Appendix Appendix A Olive mills questionnaire Olive mills survey input data Three-phase extraction process photography from study area Appendix B Gallic acid calibration curve report Appendix C Thermogravimetric analysis report (TGA Q50) Activated olive stones preparation Quantichrome NovaWin BET surface area analysis reports
Page 184 184 187 191 194 194 195 195 196 197
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Removal of Polyphenols from Olive Mill Wastewater using Activated Olive Stones By Ruba Abdelrahman Farid Aladham Supervisor Dr. Hafez Q. Shaheen Dr. Shehdeh W. Jodeh
Abstract Extremely high organic loaded aqueous waste is seasonally generated from the olive oil extraction process, so called Olive Mill Wastewater (OMWW). In Palestine OMWW is disposed directly to sewerage system or wadies, whereas the solid waste (olive husk) is dumped into lands nearby the olive mills without treatment. This increases the risk of contaminating soil, surface water resources, and groundwater aquifers. The negative environmental impact of OMWW is attributed to poor biodegradation and toxicity of polyphenols present in OMWW. This work is focused on studying the environmental state of art of olive mills operating in the northern areas of West Bank. It also investigates the feasibility of transforming olives solid residue (olive stones) into an effective, high capacity low cost adsorbent for total phenol removal from OMWW. Olive mills survey analysis for 2010 olive season indicates that (1.25 m3 OMWW/ton olives) and (350 kg olive husk/ton olives) are generated from three-phase extraction process; accounting for 90128.9 m3 OMWW and 26584.7 kg olive husk produced in the study area. Characterization of OMWW reveals that high fractions of polyphenols (Avg. 4592.0 mg/l) are
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lost in OMWW with 0.031 total phenol/COD content. The pollution load of OMWW is extremely high, equivalent to about 2.2 million capita. A highly micropours activated carbon, with 368.3 m2/g BET surface area, is chemically prepared from olive stones using potassium hydroxide (KOH) as an activating agent. The produced activated olive stones (AOLS) exhibit high total phenol adsorption capacity. Adsorption equilibrium is represented by Langmuir isotherm model (qmax=333.3 mg/g). Total phenol adsorption kinetics is best modeled by pseudo-second order reaction rate and Dumwald –Wagner (intra-particle) diffusion model. Reduction of total phenol content in OMWW is achieved in mini column test of AOLS fixed bed adsorption. The effluent from AOLS fixed bed meets Palestinian standard for wastewater discharge. Thomas, Bohart-Adams and YoonNelson models predicts the breakthrough curve of total phenol adsorption in AOLS fixed bed. Thomas model parameters of the breakthrough curve are employed for the design configuration of full-scale AOLS fixed bed for total phenol adsorption from OMWW. The thesis recommendations promote for olive extraction waste management policy and OMWW quality monitoring program. It also calls for further research to optimize the performance of fixed bed adsorption for OMWW pre-treatment and its possible integration with conventional treatment processes for complete OMWW treatment in order to meet the Palestinian treated wastewater reuse standards.
1
Chapter 1 Introduction 1.1. General background Scarcity and limited access to water resources in Palestine have been a major issue, which requires preservation of existed resources from possible contamination with pollutants. Different types of point and non point pollution sources contribute to this problem, including industrial and agricultural activities. One of the major pollution sources is Olive Mill Wastewater (OMWW), generated seasonally from olive oil extraction processes. OMWW is discharged to wadies without pre-treatment, and may contaminate groundwater resources, mainly due to its high phenolic content. Pollution from OMWW is a major problem in developing countries, where sophisticated treatment technologies are too expensive. The current and future wastewater treatment plants in West Bank are designed on a basis that does not take into account sudden overloading, and shocks related to OMWW discharges, which may jeopardize their functionality. Therefore, effective and feasible pre-treatment of OMWW must be considered before discharge. 1.2.
Problem description
OMWW is the most critical waste generated from olive oil extraction processes. The annual OMWW production of the Mediterranean olive growing countries is estimated to amounts ranging from 7 to over 30 million m3 (Niaounakis et al., 2004). Olive mills in the West Bank generate
2
about 200 thousand m3/year of OMWW (Subuh, 1999), and thousands of tons of solid olive residue (olive husk) that can not be applied directly to fields without pre-treatment. The olive mills contribute largely to the core problem of surface and groundwater pollution (Naser et al. 2009). Large volumes of OMWW are produced within few months (October to December). OMWW discharge into fresh water would destroy self-purifying capabilities of these environments and seriously alter their biological balance. The poor biodegradability of OMWW inhibits possible spreading onto fields. Nonbiodegradable organic compounds (such as polyphenols and tannins) would reach waterbed and pollute it .In addition, dramatic overloading would take place in wastewater treatment plants due to OMWW spill into sewer system, as pollution of 1 m3 of OMWW is equivalent to 100-200 m3 of domestic sewage (Rozzi and Malpei, 1996). Different treatment and pretreatment options are proposed to reduce the environmental impact of OMWW. Still, the feasibility and sustainability of these processes are of big concern with reference to the scattered distribution and location of olive mills near residential areas, taking into consideration the seasonal generation of OMWW .The large amount of phenolic compounds in OMWW deaccelartes and hinders COD removal in biological processes, detracting their economic viability. Worldwide, the going trend is towards extracting polyphenol from OMWW. The activated carbon produced from olive mill solid waste was proved to be an efficient adsorbent for removal of phenol (Moreno-castilla et al., 2001). After phenol detoxification
3
process, traditional wastewater treatment processes will be able to reduce OMWW pollution load to legally accepted levels for disposal. Water in Palestine is the most precious resource, where groundwater is the main water resource. Therefore, it is required to protect water resources and apply pre-tretment to OMWW before disposal. 1.3.
Palestinian researches on OMWW management and treatment
No pre-treatment has been applied for OMWW in Palestine. The problem of OMWW has been propagated with the lack of national policy and legislations regulating olive oil industry waste management. Statistics related to olive oil extraction industry are carried out by Palestinian Central Bureau of Statistics (PCBS). They cover the economic aspects of olive oil industry without highlighting its environmental impacts quantitatively. Few Palestinian researches have been addressing the environmental impact and management of OMWW. Among these researches, Shaheen (2007) carried out a comparative study for the available OMWW treatment options. The research recommended modifying extraction process to two-phase centrifugation or the implementation of forced evaporation as the most feasible and environmental friendly treatment alternative that can be applied in Palestine. According to El-Khatib et al., (2009), 84% of COD removal from diluted OMWW was achieved using Up-Flow Anaerobic Sludge Bed (UASB). Other Palestinian researchers investigated the reuse of OMWW and solid waste. Imseeh (1997) studied the application of OMWW as water replacement for preparing concrete. Improved concrete workability and compressive strength were achieved. El-Hamouz et al.,
4
(2007) recovered the oil remaining in the solid waste (olive husk), higher than 5% of waste, by the Soxhlet extraction technique. The solid waste was successfully transformed into activated carbon to adsorb chromate ion from water. None of the above researches tackled the issue of polyphenols and its removal from OMWW. Investigating the feasibility of total phenol removal from OMWW by adsorption onto Palestinian activated olive stones is an added value to the other past and future Palestinian researches. 1.4.
Phenol detoxification from wastewater
There are different conventional and novel treatment alternatives that have been tested for the removal of phenolic compounds from wastewater. The most commonly used treatments include extraction, adsorption, ion exchange, steam distillation, membrane separation, bacterial, enzymatic and chemical oxidation, in addition to electrochemical techniques (Narayan and Agrawal, 2012). Most of these alternatives have the problem of high cost and low efficiency and generation of toxic products especially for high phenol concentration in wastewater (Nazari et al., 2004). Biological treatment suffers from sever susbtrate inhibition for wastewater with high phenolic content (Prieto et al., 2002). The presence of other conatimnants significantly decreases the enzyme activity or permanently denatures the enzyme and thus there is a need to add continuously fresh enzyme at regular intervals (Zhang et al., 2007). The chemical oxidation as well as extraction requires the addition of large quantities of chemicals, which is infeasible from economical and environmental point of view. Steam distillation
and
electrochemical
techniques
require
high
energy
5
consumption and in most cases they result in incomplete treatment (Narayan and Agrawal, 2012). On the other hand, adsorption, using activated carbon, is the most widely used technique for the removal of organic compounds (Improlive, 2000). Many researchers have overcome the problem of activated carbon high cost through developing low cost high capacity alternative adsorbents from conventional and non-conventional wastes (Bhatnagar, 2006). This Thesis investigates transforming olives' solid residue (olive stones) into an effective, high capacity low cost adsorbent for total phenol removal from OMWW as a pretreatment. 1.5.
Research hypothesis
The research is based on the hypothesis that olive stones, obtained from three-phase olive oil extraction process, can be efficiently activated into a low cost adsorbent with high capacity for total phenol detoxification from OMWW. 1.6.
Objectives
This research aims to reduce the negative environmental impact of OMWW in Palestine. The following objectives serve the goal of this research, which are: • Investigate the environmental state of art of olive mills operating in northern West Bank. • Investigate the feasibility of total phenol removal from OMWW onto activated Palestinian olive stones.
6
1.7.
Study area
The study area, as depicted in Fig (1.1), is covering the northern West Bank olive mills (Nablus, Jenin and Tubas, Tulkarem Qalqilya and Salfit), which contribute for 84.2% of total olive oil production in the West Bank (PCBS, 2011). The study area is located within the Mediterranean climate zone (Qutub, 2010); characterized by long hot summer and short cool winter with average annual rainfall of 521.2 mm, 25.0ºC, 15.5ºC average maximum and minimum air temperatures, respectively, and 62.5% average humidity (PCBS, 2010). These climatic conditions put the northern West Bank at the top of olive producing areas in Palestine (Khatib, 2008). Different olive cultivars are found in the study area, which vary in characteristics and oil content as depicted in Table (2.1).
Fig (1.1): Study area delineation (Source: modified from Naser et al., 2007)
7
Table (1.1): Main olive cultivars in the study area Oil content (%) 40.1 23.3 47.4
Total phenol content (mg/kg oil) 152 238 801
Manzolino
50.3
201
Nabali
50.7
415
Nabali (Improved)
44.5
523
Shami Souri
55.1 26.0
474 610
Cultivar Chemlali Jaba' K18
Location Jenin Jenin Tulkarem Tulkarem and Nablus Tulkarem, Jenin, Nablus and Qalqilya Tulkarem, Jenin, Nablus and Qalqilya Nablus Tulkarem and Jenin
Source: (Qutub et al., 2010)
1.7.1. Olive oil extraction in the study area According to (PCBS, 2011) 191 olive mills are operating in the study area. 82.7% of these olive mills are full automatic. The study area contributes to 84.2% of total olive oil production in the West Bank (18452.3 kg oil during 2010 olive season). Table (2.2) presents the distribution of the olive mills in northern West Bank. Table (1.2): Distribution of olive mills in northern West Bank Governorate
# of olive mills
Percentage (%)
Jenin and Tubas
61
31.9
Nablus
51
26.7
Tulkarem
37
19.4
Qalqilya
17
8.9
Salfit
25
13.1
Total
191
100
Source: (PCBS, 2011)
8
1.7.2. Questionnaire sample size The sample size required for the olive mills survey is estimated according to Finite Population Correction Formula (Daniel, 1999): 0 123 4 15 ./ 6 2 4 35 7 0 123 4 15
3832398:5 ;98
