Odours in Wastewater Treatment Measurement, Modelling and Control
Edited by
Richard Stuetz School of Water Sciences, Cranfield University, UK and
Franz-Bernd Frechen Department of Sanitary and Environmental Engineering, University of Kassel, Germany
Published by IWA Publishing, Alliance House, 12 Caxton Street, London SW1H 0QS, UK Telephone: +44 (0) 20 7654 5500; Fax: +44 (0) 20 7654 5555; Email:
[email protected] www.iwapublishing.com First published 2001 © 2001 IWA Publishing Printed by TJ International (Ltd), Padstow, Cornwall, UK Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright, Designs and Patents Act (1998), no part of this publication may be reproduced, stored or transmitted in any form or by an means, without the prior permission in writing of the publisher, or, in the case of photographic reproduction, in accordance with the terms of licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licenses issued by the appropriate reproduction rights organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to IWA Publishing at the address printed above. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for errors or omissions that may be made. British Library Cataloguing in Publication Data A CIP catalogue record for this book is available from the British Library Library of Congress Cataloging- in-Publication Data A catalog record for this book is available from the Library of Congress
ISBN 1 900222 46 9
Contents
Preface List of Contributors
xi xiii
PART I: INTRODUCTION
1
1 1.1 1.2 1.3 1.4
Odour perception Introduction Human perception of odours Odour complaints References
3 3 4 10 13
2 2.1 2.2 2.3 2.4 2.5 2.6 2.7
Regulations and policies Introduction Components of the problem What type of standard? Environmental protection policy Some conclusions Acknowledgements References
16 16 17 18 25 29 30 30
[v]
vi
Contents
PART II: ODOURS ASSOCIATED WITH WASTEWATER TREATMENT
31
3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8
Odour formation in sewer networks Introduction Microbial processes in sewers related to odour formation Volatile organic compounds produced under anaerobic conditions in sewers Emission of odours from sewers Prediction of hydrogen sulphide in sewer networks Examples of simulations with the sewer process model Control of odours from sewers References
33 33 35 40 42 55 62 63 65
4 4.1 4.2 4.3 4.4
Sources of odours in wastewater treatment Introduction Sources of odours in wastewater and sludge Release of odours to the atmosphere Design to minimise odour problems associated with wastewater treatment processes References
69 69 70 79 84
4.5
PART III: ODOUR SAMPLING AND MEASUREMENT
90 93
5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9
Sampling techniques for odour measurements Introduction Odour impact assessment and sampling program design Sample collection - general principles Sample collection from point sources Sample collection from area sources Sample collection from volume (building) sources Result calculation Conclusions References
95 95 98 101 105 107 112 114 118 119
6 6.1 6.2 6.3 6.4 6.5 6.6
Hydrogen sulphide measurement Introduction Hydrogen sulphide Hydrogen sulphide measurement Linking H2S and odour concentration Conclusions References
120 120 121 122 127 128 129
Contents
vii
7 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.11 7.12
Olfactometry and the CEN standard prEN 17325 Introduction The essence of quantitative olfactometry The development of the CEN standard Types of dynamic dilution olfactometry Compliance with the CEN standard Sampling considerations Qualitative assessments combined with the CEN standard Conclusions Acknowledgements References Terms and definitions from the CEN standard Abbreviations
130 130 131 133 136 141 143 144 148 149 149 149 154
8 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9
Odour analysis by gas chromatography Introduction Pre-concentration of sample Gas chromatography Choice of chromatography column Choice of detector Review of gas chromatography of odours Emission rates Case study References
155 155 160 164 166 168 169 172 173 175
9 9.1 9.2 9.3 9.4
Odour measurements using sensor arrays Introduction Sensor array technology Application of sensor arrays to odour monitoring References
179 179 180 190 196
PART IV: ASSESSMENT AND PREDICTION OF ODOURS
199
10 10.1 10.2 10.3 10.4 10.5 10.6
201 201 204 205 209 212 212
Prediction of odorous emissions Introduction What can we predict? How can we predict? What will we predict? Quality control References
viii 11 11.1 11.2 11.3 11.4 11.5 11.6 11.7
Contents Odour mapping using H2S measurements Introduction The mechanics of preparing an H2S map H2S monitors and interferences Interpretation of H2S maps Other uses of H2S maps Conclusions References
214 214 216 220 221 224 230 231
12 12.1 12.2 12.3 12.4
Dispersion modelling Introduction Odour dispersion modelling in practice Limitations of dispersion modelling References
232 232 239 245 249
13 13.1 13.2 13.3 13.4 13.5 13.6
Monitoring nuisance and odour modelling Introduction Specifying annoyance limits Annoyance, nuisance and complaints Annoyance and public perception Odour modelling and implications for operations and planning Reference
250 250 253 258 262 264 266
PART V: ODOUR CONTROL AND TREATMENT
267
14 14.1 14.2 14.3 14.4 14.5 14.6 14.7
Use of chemicals for septicity and odour prevention in sewer networks Introduction Septicity development in wastewater Controlling septicity using nitrate Controlling septicity using ferric Controlling septicity using ferric nitrate Controlling odour by pH adjustment References
269 269 271 274 280 288 289 292
15 15.1 15.2 15.3 15.4 15.5
Process covers for odour containment Introduction Cover materials Cover configuration Criteria for selection Bibliography
293 293 294 300 304 308
Contents
ix
16 16.1 16.2 16.3 16.4 16.5 16.6 16.7
Chemical odour scrubbing systems Introduction Chemistry of wastewater treatment odours Design of packed tower scrubbers Packed tower theory Design of mist systems Estimating costs for chemical odour control References
309 309 313 318 330 340 342 343
17 17.1 17.2 17.3 17.4 17.5 17.6 17.7
Adsorption systems for odour treatment Introduction Adsorbents Options for regeneration or disposal of spent adsorbents Characteristics of carbon beds Control of hydrogen sulphide Control of organic odorants (VOCs) References
345 345 348 356 358 360 362 362
18
365
18.1 18.2 18.3 18.4 18.5
Catalytic oxidation of odorous compounds from waste treatment processes Introduction Catalytic processes for VOC and H2S treatment in the gas phase Catalytic oxidation technologies for scrubbing liquids Catalytic oxidation for odour abatement in sanitary engineering References
19 19.1 19.2 19.3 19.4 19.5 19.6 19.7 19.8 19.9
Biotechnological treatment of sewage odours Introduction Types of reactors Basic process mechanisms Design and operational parameters Performance Process monitoring Process control Costs References
396 396 397 399 403 406 407 408 411 411
365 369 378 386 389
x 20 20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 Index
Contents Activated sludge diffusion as an odour control technique Activated sludge odour removal: description and biodegradation theory Design / operation considerations Factors affecting performance Effects on wastewater treatment Advantages over media-based systems Economics Case histories References
415 415 417 421 426 428 429 430 434 435
Preface
The release of unpleasant odours from wastewater treatment works can have an impact on the local population. Public concerns over the release of odours from these facilities have increased in recent years. This is the direct result of the encroachment of housing on land surrounding sewage works, the raised awareness of public rights over environmental issues and the expectation of the public towards privatised water companies. Consequently, careful management is required to avoid the creation and release of annoyance odours during wastewater treatment. Odorous compounds that are present or formed in sewer networks and during wastewater treatment can become an annoyance when they are released into the environment. To avoid the formation of odorous compounds requires an understanding of the processes involved. To control and prevent their release, the mechanisms by which odours are formed and then released and dispersed into the atmosphere must be understood. In Part I of this book, the reader is introduced to how humans perceive odours, the biological mechanisms involved and their interpretation in relation to the number of complaints. An overview of the philosophy and basics that form the background for regulations and policies used to enforce environment protection is presented. Part II of the book describes the formation of odours and volatiles in sewer networks and sources of odours in wastewater treatment. Particular attention is focused on the [ xi ]
xii
Preface
role of microbial interactions and the physical factors that lead to odour release during treatment. The accurate sampling and measurement of odours is essential for assessing the emission of odours as well as evaluating the efficiency of abatement technologies. Part III provides an account of the techniques used to sample odours from wastewater processes and presents the different analytical methods used to measure odours or odorants directly in the field or indirectly at a laboratory. Special attention is given to the recent draft European standard for olfactometry, the application of absorbents for concentrating odour mixtures and the use of novel sensor arrays for surrogate odour measurements. Part IV of this book covers the practical aspects of assessing and predicting the release of nuisance odours from wastewater treatment in order to provide effective control. The techniques used to predict the emission of odours from different wastewater sources are discussed with a special focus on the use and benefits of the Odour Emission Capacity measurement. Methodologies for assessing the dispersion of odorous emissions from a wastewater source are presented. Practical examples of the use of H2S contour maps, dispersions and odour models as well as experiences with monitoring nuisance are presented by the authors. The chapters in Part V provide an overview of the technologies currently used to contain and treat odorous compounds. The suppression of odour formation by the addition of chemicals to sewer and wastewater and the containment of odorous atmospheres using process covers are discussed. The different mechanisms involved in the chemical, physical and biological treatment of odours are presented as well as the results of such different types of deodorization technologies.. The book has been written for engineers and scientists who are working, researching or generally interested in the fields of odour regulation, formation, measurement, modelling and treatment. The content of the individual chapters reflects the interdisciplinary nature of the subject matter. We believe that the problem of odour nuisance, odour formation and odour abatement is of increasing interest, and from this viewpoint this book may be the first, but surely not the last project dealing with this topic. We also do hope that experiences from different countries as well as expertise from different disciplines will work together even more in the future to help with establishing a nuisance-free environment, and that this book may be a step towards this aim. We thank all the contributors of this book for their contributions and wish to acknowledge the assistance of Alan Click and Alan Peterson of IWA Publishing for their help, support and patience throughout the preparation of the book. Richard Stuetz Franz-Bernd Frechen March 2001
