1. 1 Course 1 Unit 2 Characteristics of urine, faeces and greywater Content: Part A: Characteristics of urine Part B: Characteristics of faeces Part C: Characteristics of greywater Lecturer: Dr. Elisabeth v. Münch e.vonmunch@unesco-ihe.org

2. 2 composting, anaerobic digestion organic waste soil improvement, biogas Treatment examples Reuse Substance faeces (brown water) anaerobic digestion, drying, composting biogas, soil improvement greywater (shower, washing, etc.) irrigation, groundwater recharge, toilet flushing urine (yellow water) N-rich fertiliser storage filtration, biological treatment rainwater water supply, groundwater recharge Separated „waste“ streams are easier to treat and reuse constructed wetlands, wastewater ponds, biol. treatment, membrane technology Source: GTZ-ecosan project,resource book = black water (with small amount of flush water)

3. 3 “Waste” streams discussed in this lecture 1.Urine 2.Faeces 3.Greywater 4.Anal washwater 5.Conventional domestic wastewater – for comparison purposes

4. 4 Nutrients are an important component of waste streams Macronutrients: Macronutrients: Nitrogen (N) Nitrogen (N) Phosphorus (P) Phosphorus (P) Potassium (K) Potassium (K) Sulphur Sulphur Calcium Calcium Magnesium Magnesium Micronutrients: Micronutrients: Boron, copper, iron, chloride, manganese, molybdenum and zinc Boron, copper, iron, chloride, manganese, molybdenum and zinc TN = total nitrogen, e.g. urea-N plus ammonia-N (for urine) TP = Total phosphorus A fertiliser which contains these three nutrients is called a “complete” fertiliser Course 1 Unit 2

5. 5 Role of measurement parameters for urine, faeces and greywater ParameterPurpose of measuring Dry mass, moisture content (for faeces) Solids content, mass to be transported Total nitrogen (TN), total phosphorus (TP), potassium (K), ammonia-N Nutrient content for fertiliser value (or for pollution potential if discharged to water course) COD, BOD (chemical / biological oxygen demand) Organic matter content VS (volatile solids)Organic matter content pHpH around neutral is best for reuse TDS (total dissolved salts)The lower the TDS the better for reuse Electrical conductivityProportional to TDS and correlated with ammonia-N Pathogens (e.g. helminth eggs, E. coli) Assess public health risk (but needs specialised lab to measure)

6. 6 Course 1 Unit 2 Part A: Characteristics of urine Most of the data in this part was taken from Jönsson et al. (2004)

7. 7 Fresh urine Fresh urine This amount excreted in one go by one adult in the morning (full bladder!): 730 mL pH: 7.7 TN: 19 g/L (this is unusually high) Ammonia-N: 22 mg/L (during last IHE lab session: ~160 mg/L) Source: own determinations in Triqua laboratory You see here 14 grams of nitrogen!

8. 8 Human urine quantity facts Human physiology facts: Human physiology facts: The body uses urine as a balancing medium for liquids and salts The body uses urine as a balancing medium for liquids and salts The kidneys filter urine from the blood The kidneys filter urine from the blood At excretion, the urine pH is normally around 6 but can vary between 4.5 – 8.2 At excretion, the urine pH is normally around 6 but can vary between 4.5 – 8.2 Adults excrete about 0.8 – 1.5 L of urine per day (children about half that amount) depending on time, person and circumstances: Adults excrete about 0.8 – 1.5 L of urine per day (children about half that amount) depending on time, person and circumstances: Excessive sweating results in concentrated urine Excessive sweating results in concentrated urine Comsumption of large amounts of liquid dilutes the urine Comsumption of large amounts of liquid dilutes the urine

9. 9 Nutrients in human urine Digested nutrients enter the metabolism and are excreted mostly with the urine and the rest in faeces Digested nutrients enter the metabolism and are excreted mostly with the urine and the rest in faeces Urine contains 88% of excreted N, 67% of excreted P and 73% of excreted K; the remainder is in the faeces Urine contains 88% of excreted N, 67% of excreted P and 73% of excreted K; the remainder is in the faeces This ratio of nutrient split between urine and faeces appears to be more or less the same worldwide This ratio of nutrient split between urine and faeces appears to be more or less the same worldwide

10. 10 Urea facts Of the nitrogen in fresh urine, 75-90% is in the form of urea; remainder is in the form of ammonium or creatinine Of the nitrogen in fresh urine, 75-90% is in the form of urea; remainder is in the form of ammonium or creatinine Urea is (NH 2 ) 2 CO – an organic nitrogen compound (contributing to COD a content of urine) Urea is (NH 2 ) 2 CO – an organic nitrogen compound (contributing to COD a content of urine) Urea is easily converted to ammonium by urease in the urine piping system or in the sewer Urea is easily converted to ammonium by urease in the urine piping system or in the sewer In conventional mixed wastewater, about 78% of the total nitrogen is therefore in the form of ammonia already In conventional mixed wastewater, about 78% of the total nitrogen is therefore in the form of ammonia already Urea can be made artificially from ammonia and CO 2 and is a popular fertiliser world-wide Urea can be made artificially from ammonia and CO 2 and is a popular fertiliser world-wide Urea has the highest proportion of N of all liquid fertilisers: 46.4% N in urea Urea has the highest proportion of N of all liquid fertilisers: 46.4% N in urea a COD = Chemical Oxygen Demand (see slide 18)

11. 11 Urine storage Fresh (24 March 06) One month old (24 April 06) Fresh (24 March 06) One month old (24 April 06) Three months old (28 June 06) Note the change in colour, increasing cloudiness, sediments Course 1 Unit 2

12. 12 Processes during urine storage There is a risk of losing N in the form of ammonia with the ventilated air There is a risk of losing N in the form of ammonia with the ventilated air Sludge forms where urine usually stands for a while Sludge forms where urine usually stands for a while This sludge largely consists of struvite and apatite This sludge largely consists of struvite and apatite It is formed because the pH of the urine increases to 9-9.3 due to the degradation of urea to ammonium and at this high pH, precipitation of P, Mg, Ca and NH 4 occurs It is formed because the pH of the urine increases to 9-9.3 due to the degradation of urea to ammonium and at this high pH, precipitation of P, Mg, Ca and NH 4 occurs Urine is very corrosive (use plastic or high quality concrete for storage, not metals) Urine is very corrosive (use plastic or high quality concrete for storage, not metals) Sludge/ precipitates Ammonia (gas)

13. 13 Pathogens in urine Pathogen types: bacteria, viruses, parasitic protozoa and helminths Pathogen types: bacteria, viruses, parasitic protozoa and helminths Number of pathogens in urine is very low Number of pathogens in urine is very low One pathogen of concern is Schistosoma haematobium (causing bilharziasis), where eggs can be excreted in the urine One pathogen of concern is Schistosoma haematobium (causing bilharziasis), where eggs can be excreted in the urine In areas where this pathogen is endemic, urine should not be used near freshwater sources In areas where this pathogen is endemic, urine should not be used near freshwater sources Hygiene risks associated with diverted urine are mainly a result of contamination by faeces Hygiene risks associated with diverted urine are mainly a result of contamination by faeces

14. 14 Chemical contaminants in urine Heavy metals (Cu, Zn, Cr, Ni, Pb, Cd): Heavy metals (Cu, Zn, Cr, Ni, Pb, Cd): Urine contains substances that have entered the metabolism and therefore the levels of heavy metals in urine are very low Urine contains substances that have entered the metabolism and therefore the levels of heavy metals in urine are very low Hormones (endocrine disrupters) and pharmaceuticals: Hormones (endocrine disrupters) and pharmaceuticals: A large proportion of the hormones produced by our bodies and the pharmaceuticals that we consume are excreted with the urine A large proportion of the hormones produced by our bodies and the pharmaceuticals that we consume are excreted with the urine Hormones and pharmaceuticals are degraded in natural environments with a diverse microbial activity Hormones and pharmaceuticals are degraded in natural environments with a diverse microbial activity Urine is mixed into the active topsoil and retained for months (see Course 3 “Reuse of ecosan products in agriculture”) Urine is mixed into the active topsoil and retained for months (see Course 3 “Reuse of ecosan products in agriculture”) It is far better to recycle urine to arable land than to flush the hormones and pharmaceuticals into recipient waters It is far better to recycle urine to arable land than to flush the hormones and pharmaceuticals into recipient waters

15. 15 Pharmaceutical residues in urine (continued from previous slide) You are more likely to find pharmaceutical residues in groundwater (e.g. in Berlin!) than in food crops fertilised with ecosan products You are more likely to find pharmaceutical residues in groundwater (e.g. in Berlin!) than in food crops fertilised with ecosan products The load of pharmaceutical residues from animal manure which is freely spread on land has never concerned anyone The load of pharmaceutical residues from animal manure which is freely spread on land has never concerned anyone Some research is ongoing in Europe on this aspect, but it is not an important research question for me; I think it is rather driven by some unfounded fears of human urine and some scientists who like to spend money on expensive analytical chemistry instruments (??)… Some research is ongoing in Europe on this aspect, but it is not an important research question for me; I think it is rather driven by some unfounded fears of human urine and some scientists who like to spend money on expensive analytical chemistry instruments (??)…

16. 16 Nutrient excretion by humans is directly linked to diet Diet is the main factor for amount of nutrients excreted Diet is the main factor for amount of nutrients excreted Relationship to calculate the amount of nutrients excreted (in total) from the food intake: Relationship to calculate the amount of nutrients excreted (in total) from the food intake: N = 0.13 x total food protein P = 0.011 x (total food protein + vegetal food protein) FAO statistics are available for food supply for different countries (see www.fao.org) FAO statistics are available for food supply for different countries (see www.fao.org) N N P P Diet Excreta Course 1 Unit 2

17. 17 Estimated excretion of nutrients per capita in different countries based on diet (using data and correlation mentioned on previous slide) Source: Jönsson et al. (2004), page 6

18. 18 Table 1: Excreted mass of nutrients in urine per year (typical values for Sweden) Wet masskg/cap/yr550 VolumeL/cap/yr550 Dry masskg/cap/yr21 Total nitrogen (TN)kg/cap/yr4 Total phosphorus (TP)kg/cap/yr0.37 Potassium (K)kg/cap/yr1 CODkg/cap/yr3.6 BODkg/cap/yr1.8 Useful for calculating crop demand or area required for application. Source: Jönsson et al. (2004), and Otterpohl (2003) for COD data; BOD assumed to be half of COD COD and BOD are measures of organic content; see lecture on “Fundamentals of conventional biological wastewater treatment” Values are country- specific or diet-specific (treat as guideline only!) cap = capita = person

19. 19 Table 2: Urine data - same data as in Table 1 but per day Wet massg/cap/d1507 VolumeL/cap/d1.5 Dry massg/cap/d57.5 Total nitrogen (TN)g/cap/d11.0 Total phosphorus (TP)g/cap/d1.0 Potassium (K)g/cap/d2.7 CODg/cap/d9.9

20. 20 Table 3: Urine data - same data as in Table 1 but given as concentrations Dry massmg/L38200 Total nitrogen (TN)mg/L7300 Total phosphorus (TP)mg/L670 Potassium (K)mg/L1800 CODmg/L6500 BODmg/L3250 pH-6 (4.5 – 8.2) Own determinations: CODmg/L5,200 – 10,300 VS (volatile solids) content%16-32 Electrical conductivity (EC)  S/cm 10,600 – 25,100 TDS (total dissolved solids)mg/L 7,800 – 18,000 Concentrations are useful when working with urine of unknown number of people Results from lab session on 20 Sept 06 with 18 MSc students Urine is “very salty”

21. 21 Some additional information on TDS and EC For conventional wastewater, the following relationship holds (Metcalf and Eddy, page 56) For conventional wastewater, the following relationship holds (Metcalf and Eddy, page 56) TDS (mg/L) ~= EC (S/cm) x (0.55 – 0.70) or TDS (mg/L) ~= EC (S/cm) x (0.55 – 0.70) or EC (S/cm) ~= 1.6 x TDS (mg/L) EC (S/cm) ~= 1.6 x TDS (mg/L) Urine is not to be used as irrigation water, but as a fertiliser Urine is not to be used as irrigation water, but as a fertiliser Nevertheless, the classification of water in regards to saltiness is shown below for comparison purposes: Nevertheless, the classification of water in regards to saltiness is shown below for comparison purposes: Name of waterTDS (mg/L) Non-saline< 500 Slightly saline> 500 – 1,500 Moderately saline> 1,500 – 7,000 Highly saline> 7,000 – 15,000 Very highly saline> 15,000 – 35,000 Seawater> 35,000

22. 22 Course 1 Unit 2 Part B: Characteristics of faeces Most of the data in this part was taken from Jönsson et al. (2004)

23. 23 Faeces quantity and content Faeces consist mainly of non-matabolised material combined with some matabolised material Faeces consist mainly of non-matabolised material combined with some matabolised material Undigested nutrients are excreted with the faeces Undigested nutrients are excreted with the faeces The lower the digestibility of the diet, the higher the mass of faeces excreted per day (e.g. Sweden 51 kg/cap/yr (wet mass), China 115 kg/cap/yr, Kenya 190 kg/cap/yr) The lower the digestibility of the diet, the higher the mass of faeces excreted per day (e.g. Sweden 51 kg/cap/yr (wet mass), China 115 kg/cap/yr, Kenya 190 kg/cap/yr) Extremely high number of many different pathogens Extremely high number of many different pathogens Heavy metal content in faeces is higher than in urine (heavy metals pass through the intestine unaffected) Heavy metal content in faeces is higher than in urine (heavy metals pass through the intestine unaffected) Concentrations of contaminating substance in faeces are usually lower than in chemical ferilisers (e.g. cadmium) and farmyard manure Concentrations of contaminating substance in faeces are usually lower than in chemical ferilisers (e.g. cadmium) and farmyard manure Course 1 Unit 2

24. 24 What does it look like when faeces dry out? (Children have no problem with faeces…)

25. 25 Air drying of faeces Fresh faeces (14 May 06) 2 days old (16 May 06) 2 weeks old (1 June 06) 6 weeks old (28 June 06)

26. 26 After two weeks of drying: appears totally dry, Trial # 1 Faeces of a 2.5 year old girl Dead flies: container was covered but holes in lid, flies could not get out (??)

27. 27 Data of own faeces drying trials StartEnd Trial # 1 (drying time 14 days) Weight (g)6015 Water lost (g)45 g Moisture (calculated) (%)75 Dimensions (cm)4 x 6 x 2.53 x 4.5 x 2 Volume (mL)6027 Density (kg/L)1.170.55 Trial # 2 (drying time 12 days) Weight7020 Moisture (calculated) (%)71

28. 28 Table 4: Excreted mass of nutrients in faeces per year (typical values for Sweden) Wet masskg/cap/yr51 Volume (at excretion i.e. before drying) L/cap/yr51 Dry masskg/cap/yr11 Total nitrogenkg/cap/yr0.55 Total phosphoruskg/cap/yr0.18 Potassiumkg/cap/yr0.4 CODkg/cap/yr14 BODkg/cap/yr7 Useful for calculating crop demand or area required for application Source: Jönsson et al. (2004), and Otterpohl (2003) for COD BOD assumed to be half of COD Values are country-specific or diet-specific (treat as guideline only!) = weight of a medium-weight backpack Course 1 Unit 2

29. 29 Table 5: Faeces data - same data as in Table 4 but per day Wet massg/cap/d140 Volume (at excretion)L/cap/d0.1 Dry massg/cap/d30 Total nitrogeng/cap/d1.5 Total phosphorusg/cap/d0.5 Potassiumg/cap/d1.1 CODg/cap/d39 this is the mass of wet faecal matter excreted per person per day this is the mass of faeces after drying, per person per day (= a letter containing 6 DIN- A4 pages) For comparison: solid waste production is 200 – 500 g/cap/d in cities in India (Source: Rothenberger et al., 2006, page 93)

30. 30 Table 6: Faeces data - same data as in Table 4 but given as concentrations in g/kg wet mass Dry mass (at excretion) g/kg216 Total nitrogen (TN)g/kg11 Total phosphorus (TP) g/kg4 Potassiumg/kg8 Moisture content%78 Dry matter content (at excretion) %22 pH - 7 – 9 (?) Useful when working with faeces of unknown number of people How to measure the organic content (COD and BOD were developed for liquids)?  Volatile solids content or ignition loss; TOC How to measure pH? Dilution with water + shaking, or pH meter for soil

31. 31 Course 1 Unit 2 Part C: Characteristics of greywater

32. 32 Greywater - definition Greywater is domestic wastewater with no or minimal human excrements Greywater is domestic wastewater with no or minimal human excrements Sources are kitchens, baths, showers, laundry, washing Sources are kitchens, baths, showers, laundry, washing Some faecal matter enters if nappies are washed in the laundry for example Some faecal matter enters if nappies are washed in the laundry for example (households where people use pit latrines generate greywater automatically)

33. 33 Greywater quantities generated Range: 60 – 275 L/cap/d (depending on country and wealth/attitude of user) Range: 60 – 275 L/cap/d (depending on country and wealth/attitude of user) Some new houses in Germany, Norway, Sweden: less than 100 L/cap/d Some new houses in Germany, Norway, Sweden: less than 100 L/cap/d Rural Jordan example: 20 L/cap/d (water is precious, so is used several times) Rural Jordan example: 20 L/cap/d (water is precious, so is used several times) Note: Basic lifeline water requirement: 25 or 50 L/cap/d (Gleick, 1998) Note: Basic lifeline water requirement: 25 or 50 L/cap/d (Gleick, 1998) For comparison: Drinking water requirement: 3-5 L/cap/d For comparison: Drinking water requirement: 3-5 L/cap/d

34. 34 Greywater characteristics: organic matter, nutrients, pollutants Organic matter (BOD): High concentrations of easily degradable organic material, e.g. fat, oil and other organic substances from cooking, residues from soap, shampoos and tensides from detergents Organic matter (BOD): High concentrations of easily degradable organic material, e.g. fat, oil and other organic substances from cooking, residues from soap, shampoos and tensides from detergents Nutrients: Nutrients: Nitrogen levels low Nitrogen levels low Phosphorus input from washing and dish-washing powder (for water softening) – some countries, e.g. Norway, have banned washing powder containing P Phosphorus input from washing and dish-washing powder (for water softening) – some countries, e.g. Norway, have banned washing powder containing P Metals and other toxic pollutants: Metals originating from water itself, corrosion of pipe system, dust, cutlery, dyes, shampoos (similar to conventional wastewater) Metals and other toxic pollutants: Metals originating from water itself, corrosion of pipe system, dust, cutlery, dyes, shampoos (similar to conventional wastewater) Source: Ridderstolpe (2004)

35. 35 Greywater characteristics: pathogens Proportion of pathogens is low (some faecal contamination possible) Proportion of pathogens is low (some faecal contamination possible) Greywater has lower pathogen content than effluent from most advanced wastewater treatment plants Greywater has lower pathogen content than effluent from most advanced wastewater treatment plants Amount of faeces in greywater: Amount of faeces in greywater: Based on measured faecal sterols, the estimate is that about 0.04 g/cap/d of faeces is mixed into the greywater Based on measured faecal sterols, the estimate is that about 0.04 g/cap/d of faeces is mixed into the greywater Note: use of indicator bacteria might be misleading to measure the amount of faeces in greywater because of growth on organic matter that is contained in greywater Note: use of indicator bacteria might be misleading to measure the amount of faeces in greywater because of growth on organic matter that is contained in greywater Source: Ridderstolpe (2004)

36. 36 Table 7: Greywater characteristics VolumeL/cap/d 60 - 275 Total suspended solids (TSS) mg/L365 Total nitrogen (TN) mg/L6 Total phosphorus (TP) mg/L3 Potassiummg/L15 CODmg/L562 BODmg/L281 pH -7-8 Only to provide an idea – highly variable and dependent on water use patterns Concentrations are based on Otterpohl (2003) mass flows, and flowrate of 60 L/cap/d Course 1 Unit 2

37. 37 Anal cleansing materials used world- wide Toilet paper: collect in faeces compartment if material to be composted or incinerated, otherwise store separately Toilet paper: collect in faeces compartment if material to be composted or incinerated, otherwise store separately Water (see next slide) Water (see next slide) Vegetable materials: collect in faeces compartment Vegetable materials: collect in faeces compartment Stones or rags: collect separately Stones or rags: collect separately Newspaper, card board: treat same as toilet paper Newspaper, card board: treat same as toilet paper Note: absence of anal cleansing material next to the toilet can lead to higher incidence of diarrhoea (Herbst, 2006)

38. 38 Anal washwater Origin: Practise of many cultures (e.g. Muslims and Buddhists) to wash anal area after defecating and after urinating Origin: Practise of many cultures (e.g. Muslims and Buddhists) to wash anal area after defecating and after urinating = Water with a low level of faecal matter = Water with a low level of faecal matter Treatment methods for anal washwater similar to those for greywater, e.g. constructed wetlands, soil infiltration Treatment methods for anal washwater similar to those for greywater, e.g. constructed wetlands, soil infiltration Poorly characterised (few studies) Poorly characterised (few studies) Should not be mixed with urine; can be mixed with greywater Should not be mixed with urine; can be mixed with greywater

39. 39 Table 8: Summary table of mass of nutrients in urine, faeces and greywater ParameterUnitUrineFaecesTotal % in uri ne Grey- wa ter Wet masskg/cap/yr5505160192%21900 Volume (before drying) L/cap/yr5505160192%21900 Dry masskg/cap/yr21113266%8 Total nitrogenkg/cap/yr40.554.5588%0.14 Total phosphoruskg/cap/yr0.370.180.5567%0.08 Potassiumkg/cap/yr10.41.471%0.32 CODkg/cap/yr3.61417.720%12 BODkg/cap/yr1.878.8520%6.2 For greywater used 60 L/cap/d (quite low consumption) Source: Jönsson et al. (2004), and Otterpohl (2003) for greywater data and COD. BOD assumed to be half of COD

40. 40 24,000 – 100,000 L/cap/yr 500 L/cap/yr 50 L/cap/yr Source: Otterpohl (2003) Volume of greywater, urine and faeces greywater urine faeces Note large variation in volume (related to country and standard of living) – 66 to 274 L/cap/d L/cap/year Course 1 Unit 2 Can be a good source of irrigation water if managed safely

41. 41 N P K Mass of nutrients greywaterurine faeces Source: Otterpohl (2003) kg/cap/year This is a „complete“ fertiliser (= containing N, P, K)

42. 42 Mass of organic matter (COD) Source: Otterpohl (2003) kg/cap/year greywaterurine faeces Highly beneficial when applied to soil as soil conditioner (see Course 3 Unit 1 „Reuse of ecosan products in agriculture)

43. 43 For comparison: conventional domestic wastewater Wastewater from households connected to a sewer system, without any separation of waste streams Wastewater from households connected to a sewer system, without any separation of waste streams Polluted water with high levels of pathogens Polluted water with high levels of pathogens Large volumes that need treatment Large volumes that need treatment Industrial effluent (untreated or pre- treated) is mostly mixed together with domestic wastewater Industrial effluent (untreated or pre- treated) is mostly mixed together with domestic wastewater

44. 44 Table 9: Overview of characteristics of “waste” streams Parameter (concentrat ions) UrineFaecesGrey- water Convent. domestic ww Organic solid waste TSSLN/AMM Nitrogen H MLMM PhosphorusLM M ML Organic matter (COD, BOD) LH M HH PathogensL H LHL Heavy metals LLMML L Low M Medium H High N/A Not applicable Toxic substances: heavy metals, pesticides, chlorinated organic compounds etc. Course 1 Unit 2

45. 45 Table 10: Comparison with conventional domestic wastewater ParameterUrineFaecesGreywaterConvent. domestic ww a Volume, L/cap/year 5505124,000 – 100,000 95,000 Nitrogen, kgN/cap/year 4.00.550.145.8 Phosphorus, kgP/cap/year 0.370.180.080.5 Organic matter, kgCOD/cap/year 3.6141255 Source: Otterpohl (2003)(for faeces, urine andgreywater data) a For US conditions: 260 L/cap/d, 16 gN/cap/d, 1.5 g P/cap/d, 68 gBOD/cap/d, 150 gCOD/cap/d cap = capita = person

46. 46 References Gleick, P. H. (1998) The human right to water, Water Policy 1, p. 487-503 Gleick, P. H. (1998) The human right to water, Water Policy 1, p. 487-503 Herbst, S. (2006) Water, sanitation, hygiene and diarrheal diseases in the Aral Sea area (Khorezm, Uzbekistan). PhD thesis, University of Bonn (available: sherbst@ukb.uni-bonn.de) Herbst, S. (2006) Water, sanitation, hygiene and diarrheal diseases in the Aral Sea area (Khorezm, Uzbekistan). PhD thesis, University of Bonn (available: sherbst@ukb.uni-bonn.de) Jönsson, H, Richert Stinzing, A., Vinneras, B., Salomon, E. (2004) Guidelines on the Use of Urine and Faeces in Crop Production, Stockholm Environment Institute (get from www.ecosanres.org) Jönsson, H, Richert Stinzing, A., Vinneras, B., Salomon, E. (2004) Guidelines on the Use of Urine and Faeces in Crop Production, Stockholm Environment Institute (get from www.ecosanres.org) Otterpohl, R. (2003) New technological development in ecological sanitation. Proceedings of 2nd international symposium on ecological sanitation, April 2003, Lübeck, Germany, p. 455 (in IHE library) Otterpohl, R. (2003) New technological development in ecological sanitation. Proceedings of 2nd international symposium on ecological sanitation, April 2003, Lübeck, Germany, p. 455 (in IHE library) Ridderstolpe, P. (2004) Introduction to greywater management, Stockholm Environment Institute, Sweden (get from www.ecosanres.org) Ridderstolpe, P. (2004) Introduction to greywater management, Stockholm Environment Institute, Sweden (get from www.ecosanres.org) Rothenberger, S., Zurbrügg, C., Enayetullah, I., and Maqsood Sinha, A. H. M. (2006) Decentralised composting for cities of low- and middle-income countries - A users' manual, Eawag/Sandec (Switzerland) and Waste Concern (Bangladesh), Dübendorf, Switzerland. Available: www.sandec.ch. Rothenberger, S., Zurbrügg, C., Enayetullah, I., and Maqsood Sinha, A. H. M. (2006) Decentralised composting for cities of low- and middle-income countries - A users' manual, Eawag/Sandec (Switzerland) and Waste Concern (Bangladesh), Dübendorf, Switzerland. Available: www.sandec.ch.www.sandec.ch Tchobanoglous, G., Burton, F.L., Stensel, H.D. (2003) Wastewater Engineering, Treatment and Reuse, Metcalf & Eddy, Inc., McGraw-Hill, 4th edition. Good book on conventional wastewater treatment Tchobanoglous, G., Burton, F.L., Stensel, H.D. (2003) Wastewater Engineering, Treatment and Reuse, Metcalf & Eddy, Inc., McGraw-Hill, 4th edition. Good book on conventional wastewater treatment