‘This book represents the best modern innovative thinking on the topic and symbolizes an important turning point in the history of wastewater reuse in irrigation as a major Edited by Pay Drechsel, Christopher A. Scott, contributor to water and nutrient conservation, public health and welfare.’ Hillel Shuval, Hadassah Academic College and Hebrew University, Jerusalem, Israel Liqa Raschid-Sally, Mark Redwood and Akiça Bahri Wastewater IrrigationWastewater ‘This is a tremendously useful book with its clear focus on developing countries where Akiça Bahri and Mark Redwood Liqa Raschid-Sally, A. Scott, Christopher Pay Drechsel, Edited by wastewater treatment does not work. It is also a great resource for students.’ Sasha Koo-Oshima, Food and Agriculture Organization of the United Nations ‘This book is a very useful background publication for students and professionals who would like to critically assess the interaction between public health, wastewater treatment and reuse in agriculture.’ Thor Axel Stenström, Swedish Institute for Infectious Disease Control, Stockholm Wastewater In most developing countries wastewater treatment systems have very low coverage or function poorly, resulting in large-scale water pollution and the use of poor-quality water for crop irrigation, especially in the vicinity of urban centres. This can pose significant risks to public health, particularly where crops are eaten raw. Irrigation Wastewater Irrigation and Health approaches this serious problem from a practical and realistic perspective, addressing the issues of health risk assessment and reduction in developing country settings. The book therefore complements other books on the topic of wastewater which focus on high-end treatment options and the use of treated wastewater. This book moves the debate forward by covering also the common reality of untreated wastewater, greywater and excreta use. It presents the state-of-the-art on quantitative risk and Health assessment and low-cost options for health risk reduction, from treatment to on-farm and off-farm measures, in support of the multiple barrier approach of the 2006 guidelines for safe wastewater irrigation published by the World Health Organization. The 38 authors and co-authors are international key experts in the field of wastewater irrigation representing a mix of agronomists, engineers, social scientists and public health experts from Africa, Asia, and Health Assessing and Mitigating Europe, North America and Australia. The chapters highlight experiences across the developing world with reference to various case studies from sub-Saharan Africa, Asia, Mexico and Risk in Low-Income Countries the Middle East. The book also addresses options for resource recovery and wastewater governance, thus clearly establishes a connection between agriculture, health and sanitation, which is often the missing link in the current discussion on ‘making wastewater an asset’. Pay Drechsel is Global Theme Leader on Water Quality, Health and Environment at the International Water Management Institute (IWMI), Sri Lanka. Christopher A. Scott is Assistant Professor of Water Resources Policy and Geography & Development at the University of Arizona, USA. Liqa Raschid-Sally is Senior Wastewater Irrigation Expert at IWMI, Ghana. Mark Redwood is the Urban Poverty and Environment Program Leader at the International Development Research Centre (IDRC), Canada. Akiça Bahri is Director for Africa at IWMI, Ghana. ISBN 978-1-84407-796-0 9 781844 077960 Earthscan strives to minimize its impact on the environment www.earthscan.co.uk Water / Agriculture and Food / Development Wastewater Irrigation and Health Wastewater Irrigation and Health Assessing and Mitigating Risk in Low-Income Countries Edited by Pay Drechsel, Christopher A. Scott, Liqa Raschid-Sally, Mark Redwood and Akiça Bahri publishing for a sustainable future London • Sterling, VA First published by Earthscan with the International Development Research Centre (IDRC) and the International Water Management Institute (IWMI) in the UK and USA in 2010 Copyright © International Water Management Institute and International Development Research Centre, 2010 All rights reserved ISBN 978-1-84407-795-3 hardback ISBN 978-1-84407-796-0 paperback Typeset by JS Typesetting Ltd, Porthcawl, Mid Glamorgan Cover design by Ruth Bateson For a full list of publications please contact: Earthscan Dunstan House 14a St Cross Street London EC1N 8XA, UK Tel: +44 (0)20 7841 1930 Fax: +44 (0)20 7242 1474 Email: [email protected] Web: www.earthscan.co.uk 22883 Quicksilver Drive, Sterling, VA 20166-2012, USA Earthscan publishes in association with the International Institute for Environment and Development IDRC publishes an e-book edition of this book (ISBN 978-1-55250-475-8) For further information, please contact: International Development Research Centre PO Box 8500 Ottawa, ON Canada K1G 3H9 Email: [email protected] Web: www.idrc.ca IDRC is a Canadian public corporation that works in close collaboration with researchers from the developing world with the aim of building healthier, more equitable and more prosperous societies A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data Wastewater irrigation and health : assessing and mitigating risk in low-income countries / edited by Pay Drechsel … [et al.]. p. ; cm. Includes bibliographical references and index. ISBN 978-1-84407-795-3 (hardback) – ISBN 978-1-84407-796-0 (pbk.) 1. Sewage irrigation–Developing countries. 2. Sewage–Health aspects. 3. Public health–Developing countries. I. Drechsel, Pay. [DNLM: 1. Sewage. 2. Water Purification. 3. Agriculture–methods. 4. Developing Countries. 5. Risk Assessment. WA 690 W323 2009] TD760.W345 2009 363.72’84--dc22 2009029309 At Earthscan we strive to minimize our environmental impacts and carbon footprint through reducing waste, recycling and offsetting our CO2 emissions, including those created through publication of this book. For more details of our environmental policy, see www.earthscan.co.uk. This book was printed in the UK by MPG Books, an ISO 14001 accredited company. The paper used is FSC certified. Contents Figures, Tables and Boxes ix Foreword by Hillel Shuval xv Preface xix Contributors and Reviewers xxi Abbreviations xxv PART 1 — SETTING THE STAGE 1 Wastewater, Sludge and Excreta Use in Developing Countries: An Overview 3 Blanca Jiménez, Pay Drechsel, Doulaye Koné, Akiça Bahri, Liqa Raschid-Sally and Manzoor Qadir 2 Assessing and Mitigating Wastewater-Related Health Risks in Low-Income Countries: An Introduction 29 Robert Bos, Richard Carr and Bernard Keraita PART 2 — RISKS AND RISK ASSESSMENT 3 Risk Analysis and Epidemiology: The 2006 WHO Guidelines for the Safe Use of Wastewater in Agriculture 51 Duncan Mara and Robert Bos 4 Approaches to Evaluate and Develop Health Risk-Based Standards Using Available Data 63 Inés Navarro, Peter Teunis, Christine Moe and Blanca Jiménez 5 Tools for Risk Analysis: Updating the 2006 WHO Guidelines 89 Duncan Mara, Andrew J. Hamilton, Andrew Sleigh, Natalie Karavarsamis and Razak Seidu vi WASTEWATER IRRIGATION AND HEALTH 6 Non-Pathogenic Trade-Offs of Wastewater Irrigation 101 Manzoor Qadir and Christopher A. Scott 7 Risk Analysis Integrating Livelihood and Economic Impacts of Wastewater Irrigation on Health 127 Marites M. Tiongco, Clare A. Narrod and Kelly Bidwell PART 3 — MINIMIZING HEALTH RISKS 8 Wastewater Treatment for Pathogen Removal and Nutrient Conservation: Suitable Systems for Use in Developing Countries 149 Blanca Jiménez, Duncan Mara, Richard Carr and François Brissaud 9 Low-Cost Options for Pathogen Reduction and Nutrient Recovery from Faecal Sludge 171 Doulaye Koné, Olufunke O. Cofie and Kara Nelson 10 Farm-Based Measures for Reducing Microbiological Health Risks for Consumers from Informal Wastewater-Irrigated Agriculture 189 Bernard Keraita, Flemming Konradsen and Pay Drechsel 11 Farm-Based Measures for Reducing Human and Environmental Health Risks from Chemical Constituents in Wastewater 209 Robert Simmons, Manzoor Qadir and Pay Drechsel 12 Applying the Multiple-Barrier Approach for Microbial Risk Reduction in the Post-Harvest Sector of Wastewater-Irrigated Vegetables 239 Sanja Ilic, Pay Drechsel, Philip Amoah and Jeffrey T. LeJeune 13 Cost-Effectiveness Analysis of Interventions for Diarrhoeal Disease Reduction among Consumers of Wastewater-Irrigated Lettuce in Ghana 261 Razak Seidu and Pay Drechsel PART 4 — WASTEWATER GOVERNANCE AND ADOPTION OF RISK-REDUCTION OPTIONS 14 Challenging Conventional Approaches to Managing Wastewater Use in Agriculture 287 Frans Huibers, Mark Redwood and Liqa Raschid-Sally CONTENTS vii 15 Designing Reuse-Oriented Sanitation Infrastructure: The Design for Service Planning Approach 303 Ashley Murray and Chris Buckley 16 Facilitating the Adoption of Food-Safety Interventions in the Street-Food Sector and on Farms 319 Hanna Karg, Pay Drechsel, Philip Amoah and Regina Jeitler 17 Harnessing Farmers’ Knowledge and Perceptions for Health-Risk Reduction in Wastewater-Irrigated Agriculture 337 Bernard Keraita, Pay Drechsel, Razak Seidu, Priyanie Amerasinghe, Olufunke O. Cofie and Flemming Konradsen 18 Multi-Stakeholder Processes for Managing Wastewater Use in Agriculture 355 Alexandra E. V. Evans, Liqa Raschid-Sally and Olufunke O. Cofie PART 5 — CONCLUSIONS AND OUTLOOK 19 Wastewater Irrigation and Health: Challenges and Outlook for Mitigating Risks in Low-Income Countries 381 Christopher A. Scott, Pay Drechsel, Liqa Raschid-Sally, Akiça Bahri, Duncan Mara,