IRCWD Report No. 04/85 3 5 2.0 8 6 H E ; HEALTH ASPECTS OF NIGHTSOIL AND SLUDGE USE IN AGRICULTURE AND AQUACULTURE Parti Existing Practices and Beliefs in the Utilization of Human Excreta PIERS CROSS Part II Pathogen Survival MARTIN STRAUSS [35-2. o International Reference Centre for Waste Disposal (IRCWD) Ueberlandstrasse 133, CH-8600 Duebendorf, Switzerland IRCWD Report No. 04/85 HEALTH ASPECTS OF NIGHTSOIL AND SLUDGE USE IN AGRICULTURE AND AQUACULTURE Parti Existing Practices and Beliefs in the Utilization of Human Excreta PIERS CROSS Part II Pathogen Survival MARTIN STRAUSS International Reference Centre for Waste Disposal (IRCWD) Ueberlandstrasse 133, CH-8600 Duebendorf, Switzerland WASTEWATER REUSE USE OF STORED NIGHTSOIL Farmers in Tula river basin, Mexico, Removal of decomposed, humus-like irrigating a chili field with waste- material from a dry-alkaline-fer- water from Mexico City (Photo by tilizer ("DAF") latrine in Guatemala. Ursula Blumenthal). This material is used on the fields as soil conditioner and fertilizer. NIGHTSOIL FERTILIZATION OF FISH PONDS Excreta fertilization of small fish or This fish pond owner grows fingerlings vegetable ponds through the use of over- in his excreta-fertilized pond in Bogor, hung latrines is an old tradition in the Indonesia. Others buy the fingerlings Indonesian highlands. Fish and vegetables and grow them to consumable size in are always consumed cooked. ponds not receiving any excreta. CONTENTS Page FOREWORD i ACKNOWLEDGEMENTS iv SUMMARY (Parts I, II and III) v INTRODUCTION 1 1. Purpose and Scope of Review 1 2. Excreta as a Resource 3 2.1 Agricultural Use 3 2.2 Aquacultural Use 6 2.3 Conclusion 7 3. Excreta as a Health Risk 8 3.1 Introduction 8 3.2 Faecal Microflora of Healthy, Non-Infected Persons 10 3.3 Excreted Pathogens, Diseases and Symptoms 11 3.3.1 Overview 11 3.3.2 Viruses 13 3.3.3 Bacteria 15 3.3.4 Protozoa 18 3.3.5 Helminths 18 3.4 Towards an Epidemiologically Useful Classification of Infections and Sanitation Measures 20 3.5 Pathogen Detection and Interpretation of Results 27 3.6 Excreted Pathogen Levels in Raw Human Wastes 30 4. Development and Sanitation Measures 31 5. Theoretical vs. Actual Health Risks . 33 6. Sources of Information 37 PART I: EXISTING PRACTICES AND BELIEFS IN THE UTILIZATION OF HUMAN EXCRETA 1-1 1.1 Why Consider Socio-cultural Aspects of Excreta-Re-use? 1-1 1.2 Cultural Variation in Excreta Utilization Practices 1-2 1.3 Case-Studies A: China 1-3 1.3.1 Traditional Beliefs and Practices 1-3 1.3.2 Direct Use 1-4 1.3.3 Indirect Use 1-4 1.3.4 Nightsoil Collection in Cities 1-6 1.3.5 Traditional Hygiene 1-6 1.3.6 Improving Excreta Disposal and Reuse Practices 1-6 CONTENTS (continued) 1.4 Case-Study B: Islamic Cultures 1-8 1.5 Case-Study C: Sub-Saharan Africa 1-10 1.6 Discussion 1-12 1.6.1 Cultures that Use Excreta 1-12 1.6.2 Cultures that do not Use Excreta 1-15 1.7 Conclusions and Recommendations 1-17 References 1-20 PART II: PATHOGEN SURVIVAL II-l 11.1 Principles of Pathogen Survival II-l 11.2 Survival during Storage and Treatment 11-4 11.2.1 Objectives and Boundary Conditions 11-4 11.2.2 Latrines II-5 11.2.3 Aqua Privies and Septic Tanks 11-11 11.2.4 Thermophilic Composting 11-13 11.2.5 Biogas Digesters 11-16 11.2.6 Ponds 11-19 11.2.7 Summary and Evaluation 11-25 11.3 Survival in Soil and on Crops 11-27 11.3.1 Basic Considerations 11-27 11.3.2 Survival of Helminths 11-28 1I.3.3 Survival of Bacteria 11-34 11.3.4 Survival of Viruses 11-43 11.3.5 Survival of Protozoa 11-58 11.3.6 Summary; Pathogen Survival vs. Vegetable Growth Periods 11-59 11.3.7 Patterns of Nightsoil Supply and Demand 11-62 11.3.8 Mulching or Ploughing ? 11-64 11.4 Survival in Fish 11-66 11.4.1 Basic Considerations 11-66 11.4.2 Pathogen Transmission Routes Involving Fish 11-67 11.4.3 Survival 11-70 11.5 Overall Conclusions and Recommendations 11-75 11.5.1 Conclusions 11-75 11.5.2 Recommendations 11-76 References 11-79 Appendix: Survival of Bacteria and Viruses in Fish: Literature A-l Summaries LIST OF TABLES Page Table 2.1 Characteristics of Fresh Human Excreta and Nightsoil 4 Table 2.2 Nutrient Values of Various Natural Fertilizers 4 Table 3.1 Viable Bacteria Commonly Found in Faeces of Healthy, Non-Infected Persons 10 Table 3.2 Important Pathogens Excreted in Faeces 12 Classification of Excreted Pathogens Based on Table 3.3 Epidemiological Features 22 Dominant Transmission Foci of Excreted Pathogens Table 3.4 and Suggested "Soft" and "Hard" Control Measures 25 Tentative classification model of environmental Table 3.5 infection categories associated with the relative importance played by nightsoil in transmitting certain types of pathogens 26 Table 3.6 Levels of Excreted Pathogens and Indicator Organisms in Raw Human Wastes 30 Table 5.1 Current Epidemiological Evidence of Excreted Infection Transmission Risks from Excreta Utilization in Agriculture 36 Table 5.2 Current Epidemiological Evidence of Excreted Infection Transmission Risks from Excreta Utilization in Aquaculture 37 Table I.I Examples of Human Excreta Re-use Practices 1-3 Table I I.I Major Environmental Factors Influencing Pathogen Die-Off 11-2 Table II.2 Survival of Excreted Pathogens in Nightsoil, Faeces and Sludge at 20-30 C 11-7 Table II.2a Survival of Trematode (Fluke) Eggs in Faecal Sludge at 20-30°C 11-8 Table II.3 Pathogen Content Expected in Final Product of Composting Latrines Operating Anaerobically at Ambient Temperature in Warm Climates 11-10 Table II.4 Summary: Survival of Excreted Pathogens During Pre-Application, Storage and Treatment: IDEAL-World Situation 11-25 Table II.5 Summary: Survival of Excreted Pathogens During Pre-Application, Storage and Treatment: REAL-World Situation 11-26 Table II.6 Helminth Development and Survival in Soil 11-30 Table II.7 Helminth Development and Survival on Crops 11-32 Table 11.8 Survival of Excreted Bacterial Pathogens in Soil 11-36 LIST OF TABLES (Cont.) Page Table II.9 Survival of Excreted Pathogens on Crops 11-39 Table 11.10 Virus Survival in Spread-Out, Drying Sludge 11-45 Table 11.11 Survival of Excreted Viruses in Soil 11-47 Table 11.12 Factors Affecting the Survival of Viruses in Soil 11-48 Table 11.13 Effects of Virus Adsorption State on Virus Survival 11-54 Table. 11.14 Survival of Excreted Viruses on Crops 11-57 Table 11.15 Environmental Factors Influencing Pathogen Die-Off or Survival 11-60 Table 11.16 Suggested Effects of Mulching and Ploughing on Pathogen Survival on Nightsoil Fertilized Fields 11-65 Table 11.17 Tentative Recommendations for Excreta Storage Periods in Warm Climates 11-77 LIST OF FIGURES Page Fig. 3.1 The Pathogen-Host Relationship, and Possible Transmission Routes of Excreta-Related Infections 10 Fig. 3.2 Pathogen Density and Survival Time Outside the Host 23 Fig. 3.3 Length and Dispersion of Transmission Cycles of Excreted Infections as Categorized in Table 3.3 24 Fig. II.1 Poliovirus Die-Off in Sludge-Fertilized Soil 11 -2 Fig. II.2 Salmonella Die-Off on Sewage Sludge-Irrigated Lettuce 11-2 Fig. II.3 Time-Temperature Relationship for Excreted Pathogen Survival in Nightsoil and Sludge 11 -3 Fig. 11.4 Pathogen Die-Off in Faecal Products and Treatment Periods Required at Different Temperature Regimes 11 -4 Fig. II.5 Single and Alternating-Pit (or Vault) Latrines 11 -6 Fig. II.6 Aqua Privy and Septic Tank (Schematic) 11-11 Fig. II.7 Pathogen Survival in Privies and Septic Tanks 11-12 Fig. II.8 Inactivation of Ascaris Eggs by Thermophilic Composting 11-15 Fig. II.9 Biogas Digester 11-17 Fig. 11.10 Waste Stabilization Ponds (Schematic) 11-19 Fig. II.11 Pathogen Removal in Waste Stabilization Ponds 11-24 Fig. 11.12 Pattern of Helminth Infection Cycles 11-28 Fig. 11.13 Survival Periods in Days of Excreted Bacterial Pathogens in Soils of Tropical Climates 11-37 Fig. 11.14 Survival Periods in Days of Excreted Bacterial Pathogens on Crops in Tropical Climates 11-40 Fig. II.15a Pathogen Survival in Soil vs. Vegetable Growth Periods in Warm Climates 11-61 Fig. II.15b Pathogen Survival on Crops vs. Vegetable Growth Periods in Warm Climates 11-61 Fig. 11.16 Transmission Path of Helminthic Infections Having Fish as an Intermediate Host 11-68 FOREWORD Animal and human wastes have been used in all parts of the world and for many centuries to fertilise fields and ponds where fish and aquatic vege- tables are grown. No country could afford to waste this important nutrient source. However, only in the last few decades, after having developed a high energy consuming technology to produce mineral fertilisers, many industria- lized countries ceased to recycle the nutrients contained in faecal wastes. This tendency was probably reinforced mainly by the increasing awareness of the health risks related to the use of faecal matter in agriculture, and by the low energy prices. In the United States for instance, where energy prices were very low until recently, it is still common practice to incinerate the sludge produced in communal sewage treatment plants, whereas in many European countries, where energy prices have always been considerably higher, all the animal manure and most of the sludge generated from human waste is applied to fields after appropriate treatment.