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Characteristics of Urine, Faeces, and Greywater

This course unit explores the characteristics of urine, faeces, and greywater, including nutrient content, storage processes, and potential contaminants. Learn about treatment and reuse options for these waste streams.

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Characteristics of Urine, Faeces, and Greywater

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

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

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

  4. Course 1 Unit 2 Nutrients are an important component of waste streams • Macronutrients: • Nitrogen (N) • Phosphorus (P) • Potassium (K) • Sulphur • Calcium • Magnesium • Micronutrients: • 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

  5. Role of measurement parameters for urine, faeces and greywater

  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. 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. Human urine quantity facts • Human physiology facts: • The body uses urine as a balancing medium for liquids and salts • The kidneys filter urine from the blood • 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: • Excessive sweating results in concentrated urine • Comsumption of large amounts of liquid dilutes the urine

  9. Nutrients in human urine • 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 • This ratio of nutrient split between urine and faeces appears to be more or less the same worldwide

  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 • Urea is (NH2)2CO – an organic nitrogen compound (contributing to CODa content of urine) • 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 • Urea can be made artificially from ammonia and CO2 and is a popular fertiliser world-wide • 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. Course 1 Unit 2 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

  12. Processes during urine storage • 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 • 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 NH4 occurs • Urine is very corrosive (use plastic or high quality concrete for storage, not metals) Ammonia (gas) Sludge/ precipitates

  13. Pathogens in urine • Pathogen types: bacteria, viruses, parasitic protozoa and helminths • 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 • 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

  14. Chemical contaminants in urine • 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 • 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 • 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”) • It is far better to recycle urine to arable land than to flush the hormones and pharmaceuticals into recipient waters

  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 • 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 (??)…

  16. Course 1 Unit 2 Nutrient excretion by humans is directly linked to diet N • Diet is the main factor for amount of nutrients excreted • 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) Excreta Diet N P P

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

  18. Table 1: Excreted mass of nutrients in urine per year (typical values for Sweden) Values are country-specific or diet-specific (treat as guideline only!) cap = capita = person 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”

  19. Table 2: Urine data - same data as in Table 1 but per day

  20. Table 3: Urine data - same data as in Table 1 but given as concentrations 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. Some additional information on TDS and EC • For conventional wastewater, the following relationship holds (Metcalf and Eddy, page 56) • TDS (mg/L) ~= EC (mS/cm) x (0.55 – 0.70) or • EC (mS/cm) ~= 1.6 x TDS (mg/L) • 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:

  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. Course 1 Unit 2 Faeces quantity and content • Faeces consist mainly of non-matabolised material combined with some matabolised material • 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) • Extremely high number of many different pathogens • 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

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

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

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

  27. Data of own faeces drying trials

  28. Course 1 Unit 2 Table 4: Excreted mass of nutrients in faeces per year (typical values for Sweden) Values are country-specific or diet-specific (treat as guideline only!) = weight of a medium-weight backpack 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

  29. Table 5: Faeces data - same data as in Table 4 but per day 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. Table 6: Faeces data - same data as in Table 4 but given as concentrations in g/kg wet mass 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. Course 1 Unit 2 Part C: Characteristics of greywater

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

  33. Greywater quantities generated • 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 • 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) • For comparison: Drinking water requirement: 3-5 L/cap/d

  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 • Nutrients: • 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 • 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. Greywater characteristics: pathogens • Proportion of pathogens is low (some faecal contamination possible) • Greywater has lower pathogen content than effluent from most advanced wastewater treatment plants • 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 • 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. Course 1 Unit 2 Table 7: Greywater characteristics 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

  37. Anal cleansing materials used world-wide • Toilet paper: collect in faeces compartment if material to be composted or incinerated, otherwise store separately • Water (see next slide) • Vegetable materials: collect in faeces compartment • Stones or rags: collect separately • 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. Anal washwater • 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 • Treatment methods for anal washwater similar to those for greywater, e.g. constructed wetlands, soil infiltration • Poorly characterised (few studies) • Should not be mixed with urine; can be mixed with greywater

  39. Table 8: Summary table of mass of nutrients in urine, faeces and greywater 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. Course 1 Unit 2 Volume of greywater, urine and faeces greywater urine faeces 24,000 – 100,000 L/cap/yr Can be a good source of irrigation water if managed safely L/cap/year 500 L/cap/yr 50 L/cap/yr Source: Otterpohl (2003) Note large variation in volume (related to country and standard of living) – 66 to 274 L/cap/d

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

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

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

  44. Course 1 Unit 2 Table 9: Overview of characteristics of “waste” streams L Low M Medium H High N/A Not applicable Toxic substances: heavy metals, pesticides, chlorinated organic compounds etc.

  45. Table 10: Comparison with conventional domestic wastewater Source: Otterpohl (2003) (for faeces, urine and greywater 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. References • 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) • 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) • 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. • 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

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