excreta and household wastewaters - introduction global water, sanitation and hygiene envr 890...
Post on 13-Dec-2015
Embed Size (px)
- Slide 1
Excreta and Household Wastewaters - Introduction Global Water, Sanitation and Hygiene ENVR 890 Section 003 ENVR 296 Section 003 Mark D. Sobsey February, 2006 Slide 2 Household Human Wastes and Wastewaters Slide 3 Excreta and Graywater Definitions and Properties Excreta: Human feces and urine Managed in different ways: Direct disposal on land or in water Direct use as fertilizer, soil conditioner and for aquaculture Pre-treatment prior to use Dilution with water to convey (sewage) for disposal or use Direct use of untreated (raw) sewage Treatment and discharge to land or water Treatment and reuse (agriculture, aquaculture, horticulture, industrial and civil use Graywater: Other wastewater from human activity Not directly from human fecs and urine Wastewater from washing, bathing, etc Contains human wastes and exudates Slide 4 Managing Human Excreta - Options Dry Collection: Open defecation Collect in a container e.g., chamber pot Discharge to the environment w/ or w/o Rx Latrines several kinds Treat or dispose of or both Separate feces and urine; Then, treat/store, use, dispose to the environment Slide 5 Managing Human Excreta - Options Semi-wet (or semi-dry) Use some water Pour-flush toilets and other low water use systems Slide 6 Managing Human Excreta - Options Wet Systems On-site Septic Systems Other On-site systems Soak pits Sewerage Sewage treatment systems Slide 7 Human Excreta Resource or Risk? Nitrogen (N)4.5 Phosphorous (P)0.6 Potassium1.0 Organic matter (as BOD) 35 Human excreta as a potential resource Contains nutrients (N, P, K, and organic matter) Nutrients and organic matter are: Detrimental in water, esp. surface water Eutrophication, anoxia, fish kills Beneficial on land Fertilizer, soil conditioner, land stabilizer Widely used as a fertilizer and soil amendment in both developed and developing countries Potential for excreta misuse and environmental pollution is great without proper attention to management plans and human behavior considerations Annual Amounts/Person, Kg Slide 8 Nutrient Content of Human Excreta Rich source of inorganic plant nutrients: N, P K and organic matter Daily human excretion: ~30 g of C (90 g of organic matter), ~ 10-12 g N, ~ 2 g of P and 3 g of K. Most organic matter in feces most N and P (70-80 %) in urine. K equally distributed between urine and feces. Slide 9 Organics kg COD/ (Personyear) 12.3 3.6 14.1 Volume Liter / (Personyear) 10.000 200.000 l 500 l 50 l source: Otterpohl Nutrient content kg N,P,K / (Personyear) N P K 0.8 5.3 1.0 Composition of Household Waste and Wastewater greywaterurine faeces Slide 10 of no major (or less) hygienic concern/risk volumetrically the largest portion of wastewater contains almost no (or less) nutrients (simpler treatment) may contain spent washing powders etc. 3. greywater less hygienically critical (less risk) contains the largest proportion of nutrients available to plants may contain hormones or medical residues 2. urine hygienically critical (high risk) consists of organics, nutrients and trace elements improves soil quality and increase its water retention capacity 1. feces characteristicfraction Characteristics of Human Wastes Slide 11 source: Drangert, 1998 Fertilizer Potential of Human Excreta Slide 12 treatment utilisation substances faeces (brownwater) anaerobic digestion, drying, composting biogas, soil improvement constructed wetlands, gardening, wastewater ponds, biol. treatment, membrane- technology greywater (shower, washing, etc.) irrigation, groundwater- recharge or direct reuse urine (yellowwater) liquid or dry fertiliser hygienisation by storage or drying Options for Excreta and Greywater Utilization