Excreta and Household Wastewaters - Introduction

1. Excreta and Household Wastewaters - Introduction Global Water, Sanitation and Hygiene ENVR 890 Section 003 ENVR 296 Section 003 Mark D. Sobsey February, 2006

2. Household Human Wastes and Wastewaters

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

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

5. Managing Human Excreta - Options • Semi-wet (or semi-dry) • Use some water • Pour-flush toilets and other low water use systems

6. Managing Human Excreta - Options • Wet Systems • On-site Septic Systems • Other On-site systems • Soak pits • Sewerage • Sewage treatment systems

7. Human Excreta – Resource or Risk? • 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

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.

9. 14.1 12.3 5.3 3.6 K Organics kg COD/ (Person·year) P N 1.0 0.8 Nutrient content kg N,P,K / (Person·year) Composition of Household Waste and Wastewater 10.000 – 200.000 l 50 l 500 l source: Otterpohl Volume Liter / (Person·year) greywater urine faeces

10. Characteristics of Human Wastes fraction characteristic 1. feces • hygienically critical (high risk) • consists of organics, nutrients and trace elements • improves soil quality and increase its water retention capacity 2. urine • less hygienically critical (less risk) • contains the largest proportion of nutrients available to plants • may contain hormones or medical residues 3. greywater • 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.

11. Fertilizer Potential of Human Excreta source: Drangert, 1998

12. urine (yellowwater) greywater (shower, washing, etc.) faeces (brownwater) hygienisation by storage or drying constructedwetlands, gardening, wastewater ponds, biol.treatment, membrane-technology anaerobic digestion, drying, composting liquid or dry fertiliser biogas, soil improvement irrigation, groundwater- recharge or direct reuse Options for Excreta and Greywater Utilization substances treatment utilisation