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WHO Guidelines for Safe Use of Wastewater, Excreta, and Greywater

The new WHO guidelines provide health protection measures and good practices for the safe reuse of wastewater, excreta, and greywater in agriculture and aquaculture. They are based on scientific consensus, health-based targets, and a multiple-barrier approach, and aim to maximize overall public health benefits while considering local factors.

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WHO Guidelines for Safe Use of Wastewater, Excreta, and Greywater

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  1. International Standard and Guidelines: Health and Agriculture Aspects (Ecological Sanitation Symposium, Syria, 11-13.12.2005) Christine Werner Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) GmbH ecological sanitation program, Division 44 – environment and infrastructure Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  2. Contents • WHO Guidelines • 1989 version: Guidelines for the safe use of wastewater and excreta in agriculture and aquaculture • 2005 version (upcoming): Guidelines for the safe use of wastewater, excreta and greywater • EcoSanRes Guidelines • Guidelines on  the safe use of urine and faeces in ecological sanitation systems • Guidelines on the use of urine and faeces in crop production • FAO Guidelines • FAO irrigation and drainage paper 47: wastewater treatment and use in agriculture (1992) Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  3. WHO guidelines for the safe use of wastewater and excreta in agriculture and aquaculture (1989) Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  4. New WHO guidelines for the safe use of wastewater, excreta and greywater • Upcoming WHO guidelines, update of the guidelines from 1989, publication planned in 2006 • 3 Volumes: • safe use of wastewater in agriculture • safe use of wastewater in aquaculture • safe use of excreta and greywater Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  5. New WHO guidelines for the safe use of wastewater, excreta and greywater • Reuse of wastewater, greywater and excreta in agriculture and aquaculture is practiced worldwide on a large scale, however often without sufficient health proctction measures • WHO recognise the importance of reuse of wastewater, greywater and excreta for sustainable food production and improved livelihood • WHO provides guidance on health protection measures for safe reuse • WHO recognise source-separation as a special and valid approach source: GTZ Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  6. New WHO guidelines for the safe use of wastewater, excreta and greywater The new WHO-guidelines are: • …based on: • scientific consensus and best available evidence, • health based targets • good practices and a multiple-barrier approach • …to be adapted to local social, economic, and environmental factors • …striving to maximize overall public health benefits and the beneficial use of scarce resources source: GTZ source: GTZ Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  7. new WHO guidelines for the safe use of wastewater, excreta and greywater key issue: better methodologies for evaluating risk • previous guidelines were based on actual risks using epidemiological evidence • updated guidelines make use of all available evidence including Quantitative Microbial Risk Assessment (QMRA-models) • data on different pathogens are used to develop • health based targets, • required pathogen reduction and • miocrobial performance targets of wastewater and excreta treatment systems source: GTZ source: GTZ Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  8. New WHO guidelines for the safe use of wastewater, excreta and greywater Definition: Disability Adjusted Life Years (DALYs) • DALYs are a measure of population health in terms of the burden due to a specific disease or risk factor. • DALYs attempt to measure healthy years of life lost because of disability or death from a disease • DALYs account for not only acute health effects but also for delayed and chronic effects • different health outcomes (e.g., cancer vs diarrhea) can be compared and risk management decisions can be prioritized. • adopted protection level for wastewater/excreta use in agriculture in the new WHO guideline:tolerable additional disease burden <= 10-6 DALYs or 1 µDaly per person and year= only one of a million human life years expectancy will be lost due to the potential additional disease from wastewater/excreta reuse= same protection level as used in the WHO guideline for drinking water Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  9. New WHO guidelines for the safe use of wastewater, excreta and greywater • Pathogen reductions achievable by various health protection measures for wastewater use in agriculture Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  10. New WHO guidelines for the safe use of wastewater, excreta and greywater Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  11. Verification monitoring of wastewater treatment for the various levels of wastewater treatment in Options A−G: E.coli Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  12. Health-based targets for treated wastewater use in agriculture: helminth eggs Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  13. Example: agricultural use of wastewater, Peru • Coastal region of Peru: extremely arid • Wastewater treatment in stabilisation ponds • Irrigation with treated effluent for restricted crops source: Saniplan Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  14. Example: greywater recycling through sub-surface application, India • Use of greywater in mulch trenches Mulch filled trench or pit source: GTZ Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  15. Guidelines on  the safe use of urine and faeces in ecological sanitation systems (EcoSanRes) • public health issues of agricultural reuse of urine and faeces Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  16. guidelines on  the safe use of urine and faeces in ecological sanitation systems(EcoSanRes) • focuses on the treatment and handling of faeces and urine, provides current information on risk management and assessment of source separation strategies • technical and behavioural barriers against disease transmission, sanitation treatment methods, reuse in agriculture • the scope of guideline is limited to products from urine diversion devices and dry collection systems for faeces. Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  17. Guidelines on  the safe use of urine and faeces in ecological sanitation systems (EcoSanRes) Recommendations for urine treatment and use: • The main risks in the use of excreta are related to the faecal fraction and not the urine fraction. • Technical constructions should be done in ways to minimize faecal crosscontamination. • At household level the urine can be used directly. • Urine should, in large-scale systems, be stored for one month at 20°C before use. • A withholding period of one month between fertilization and harvest should be applied. • Urine should be applied close to ground and preferably mixed with or watered into the soil. Urine strogae in Sweden (Gebers) Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  18. Guidelines on  the safe use of urine and faeces in ecological sanitation systems (EcoSanRes) Recommendations for faeces treatment and use: • Faeces should be treated before use as fertilizer. • Primary treatment (in the toilet) includes storage and alkaline treatment by addition of ash, lime or urea. • 1-2 cups (200-500 ml; enough to cover the fresh faeces) of alkaline material should be added after each defecation. • Faeces should additionally be mixed into the soil in such a way that they are well covered. • Faeces should not be used for fertilization of vegetables, fruits or root crops that are to be consumed raw, excluding fruit trees. Dried faeces (GTZ)) Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  19. Guidelines on  the safe use of urine and faeces in ecological sanitation systems (EcoSanRes) • Recommended storage time and treatment for faeces Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  20. Guidelines on the use of urine and faeces in crop production (EcoSanRes) • Agronomic issues of agricultural reuse of urine and faeces Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  21. Guidelines on the use of urine and faeces in crop production(EcoSanRes) • Requirements regarding re-using of excreta for agricultural purposes, including plant growth, nutirents in excreta, hygiene treatment of urine and faeces, etc. are discussed. • Recommendations on using excreta in cultivation are given. • It emphasizes that urine and faeces are complete fertilizers. Urine is rich in nitrogen and faeces are rich in phosphorous, potassium and organic matter. • guideline is limited to products from urine diversion devices and dry collection systems for faeces. source: GTZ source: GTZ Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  22. Guidelines on the use of urine and faeces in crop production (EcoSanRes) Recommendations for use of urine in cultivation: • Urine is a quick-acting nitrogen-rich complete fertilizer. Best effects from prior to sowing, up until two-thirds of the period between sowing and harvest. • Recommended application rate and time should be based on the desired nitrogen application rate (based on local recommendations for chemical nitrogen fertilizers) • Rule of thumb: apply the urine from one person during one day (24 hours) to one square metre of crop. (= 300-400 m2 per person and year) Fotos: Urine reuse in Havanna, Cuba (GTZ) Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  23. Guidelines on the use of urine and faeces in crop production (EcoSanRes) Recommendations for use of faeces in cultivation: • Faeces should be applied and mixed into the soil before cultivation starts. Local application in holes or furrows close to the planned plants allows for economic use • The application rate can be based on the current recommendation for the use of phosphorous-based fertilizers (low application rate with little improvement due to the added organic matter) • Faeces can also be applied at much higher rates for improving structure and water-holding capacity of the soil source: GTZ Fotos: Compost from faeces in Havanna, Cuba (GTZ) Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  24. improved soil quality through reuse of organics • restored soil fertility through nutrient reuse faeces & urine none urine source: Petter Jenssen source: Vinnerås, 2003 compost improved soil untreated soil after one week without water Beneficial effects of agricultural use of urine and faeces source: GTZ Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  25. FAO irrigation and drainage paper 47: Wastewater treatment and use in agriculture Covers health aspects and agronomic aspects of reuse of wastewater in agriculture • Draws on the WHO Guidelines (1989) for health protection measures Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  26. FAO irrigation and drainage paper 47: Wastewater treatment and use in agriculture • FAO guidelines define use restrictions with respect to salinity, trace elements, nitrogen, etc. in order to not produce negative effects on productivity and yields. • Blending conventional water with treated effluent, or using the two sources in rotation is possible. • This means that nutrients elimination in wastewater treatment is not necessary if reclaimed water can be blended with normal irrigation water. source: GTZ Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  27. Potential irrigation problem units Degree of restriction on use Salinity (Ecw1 ) dS/m < 0.7 0.7 - 3.0 > 3.0 Slight to moderate none severe Na, surface irrigation me/I < 4 4 - 10 > 10 Na, sprinkler irrigation m3/l < 3 > 3 Nitrogen (NO3-N)3 mg/l < 5 5 - 30 > 30 pH Normal range 6.5-8 FAO irrigation and drainage paper 47: wastewater treatment and use in agriculture • Water quality guidelines for maximum crop production(example) Ecological Sanitation Symposium, Syria, 11 -13 December 2005

  28. Element Recommended maximum concentration (mg/l) Remarks Cd 0.01 Toxic to beans, beets and turnips at concentrations as low as 0.1 mg/l in nutrient solutions. Conservative limits recommended due to its potential for accumulation in plants and soils to concentrations that may be harmful to humans. Cu 0.20 Toxic to a number of plants at 0.1 to 1.0 mg/l in nutrient solutions. Zn 2.0 Toxic to many plants at widely varying concentrations; reduced toxicity at pH > 6.0 and in fine textured or organic soils. Pd 5.0 Can inhibit plant cell growth at very high concentrations. FAO irrigation and drainage paper 47: wastewater treatment and use in agriculture • Threshold levels of trace elements for crop production (example) Ecological Sanitation Symposium, Syria, 11 -13 December 2005

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