Co-Composting of Faecal Sludge and Solid Waste for Urban and Peri-Urban Agriculture in Kumasi, Ghana

Programme « Gestion durable des déchets et de l’assainissement urbain » Action A09 Co-composting of Faecal Sludge and Solid Waste for Urban and Peri-urban Agriculture in Kumasi, Ghana Final Report February 2003 KMA KNUST TABLE OF CONTENTS LIST OF TABLES ........................................................................................................IV LIST OF FIGURES.......................................................................................................IV LIST OF PLATES..........................................................................................................V FOREWARD ................................................................................................................VI FEBRUARY, 2003SUMMARY .....................................................................................VI SUMMARY..................................................................................................................VII ABBREVIATIONS AND GLOSSARY ....................................................................... XIV PART A ......................................................................................................................... 1 PROJECT BACKGROUND, CONTEXT AND JUSTIFICATION................................... 1 1 INTRODUCTION .................................................................................................. 2 1.1 BACKGROUND AND JUSTIFICATION.......................................................................................................... 2 1.2 WASTE GENERATION AND MANAGEMENT............................................................................................... 3 1.3 POTENTIAL FOR WASTE RECYCLING IN URBAN AGRICULTURE IN KUMASI ............................................. 3 1.4 OBJECTIVES AND EXPECTED OUTPUT ...................................................................................................... 5 1.4.1 Objectives........................................................................................................................................ 5 1.4.2 Expected Output.............................................................................................................................. 5 1.5 SCOPE AND APPROACH ............................................................................................................................ 6 1.5.1 Scope ............................................................................................................................................... 6 1.5.2 Approach......................................................................................................................................... 6 PART B ......................................................................................................................... 8 LITERATURE REVIEW................................................................................................. 8 2 REUSE OF FAECAL SLUDGE AND, ORGANIC SOLID WASTE....................... 9 2.1 GENERAL PRACTICES OF EXCRETA AND SOLID WASTE USE .................................................................... 9 2.2 MUNICIPAL WASTE CHARACTERISTICS AND MANAGEMENT................................................................... 9 2.2.1 Faecal Sludge Characteristics and Management............................................................................ 9 2.2.2 Solid Waste Characteristics and Management.............................................................................. 11 2.2.3 The Resource Potential of Municipal Waste ................................................................................. 12 2.2.4 Municipal Organic Solid Waste .................................................................................................... 13 2.3 HEALTH CONSIDERATION IN RE-USE OF HUMAN WASTE AND SOLID WASTE........................................ 14 2.3.1 Pathogenic Health Risk................................................................................................................. 14 2.3.2 Non-Pathogenic Health Risks ....................................................................................................... 16 2.3.3 Hygienic Quality of Biosolids ....................................................................................................... 17 3 COMPOSTING AND CO-COMPOSTING .......................................................... 18 3.1 PROCESS DEFINITION ............................................................................................................................. 18 3.2 COMPOSTING SYSTEMS.......................................................................................................................... 18 3.3 KEY FACTORS OF THE COMPOSTING PROCESS ....................................................................................... 19 3.4 QUALITY OF COMPOST ........................................................................................................................... 19 3.5 QUALITY OBTAINED BY CO-COMPOSTING HUMAN WASTE ................................................................... 20 3.5.1 Nutrient Content............................................................................................................................ 20 i 3.5.2 Control of Pathogens .................................................................................................................... 21 3.6 BENEFIT OF USING COMPOST IN AGRICULTURE..................................................................................... 21 3.6.1 Influence of Compost Amendments on Physical Properties of Soil............................................... 21 3.6.2 Influence of Compost Amendments on Chemical Properties of Soil and Plants ........................... 22 3.6.3 Influence of Compost Amendments on Biological Properties of Soils .......................................... 23 3.6.4 Disease Suppression by Composts ................................................................................................ 23 3.7 CASE-STUDIES ON CO-COMPOSTING ...................................................................................................... 24 3.8 CONCLUSION ......................................................................................................................................... 28 PART C ....................................................................................................................... 29 METHODOLOGY ........................................................................................................ 29 4 METHODOLOGY ............................................................................................... 30 4.1 PLANT DESCRIPTION.............................................................................................................................. 30 4.2 TECHNICAL AND OPERATIONAL ASPECTS ............................................................................................. 31 4.2.1 Plant Operation............................................................................................................................. 31 4.2.2 Dewatering of FS .......................................................................................................................... 33 4.2.3 Co-composting of FS and SW........................................................................................................ 35 4.3 SOCIO-ECONOMIC ASPECT OF CO-COMPOSTING.................................................................... 37 4.3.1 Demand for Compost and Institutional Framework for Co-composting....................................... 37 4.3.2 Economic Appraisal of the Pilot Co-composting Plant........................................................................ 37 4.4 ASSESSMENT OF THE AGRONOMIC BENEFIT OF CO-COMPOST ............................................................... 38 PART D ....................................................................................................................... 40 RESULTS AND DISCUSSIONS ................................................................................. 40 5 DEWATERING ................................................................................................... 41 5.1 FACTORS AFFECTING SLUDGE DRYING TIME ........................................................................................ 41 5.1.1 Impact of Rain on Sludge Dewatering .......................................................................................... 42 5.1.2 Sludge Stability.............................................................................................................................. 43 5.1.3 Characteristics of Sand Layer....................................................................................................... 43 5.2 QUANTITY AND QUALITY OF BIOSOLIDS FROM FS DEWATERING .......................................................... 44 5.2.1 Microbial Parameters ................................................................................................................... 44 5.2.2 Physico-chemical Parameters....................................................................................................... 44 5.3 PERCOLATE QUANTITY AND QUALITY................................................................................................... 45 5.4 EFFICIENCY OF DRYING BEDS................................................................................................................ 46 6 COMPOSTING ..................................................................................................

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