High-level low-cost sanitation services in small towns and large villages Duncan Mara

1. High-Level Policy Dialogue on “EU Sanitation Policies and Practices in the 2008 International Year of Sanitation” High-level low-cost sanitation services in small towns and large villages Duncan Mara University of Leeds, UK

2. The Options: • On-site sanitation (e.g., pour-flush toilets + leach pits) • Low-volume flush toilets + simplified sewerage + low-cost wastewater treatment (e.g., waste stabilization ponds)

3. For example, Swedish models that use 3 litres per flush: Low-volume flush toilet

5. Simplified sewerage Rigorous hydraulic design based on: • a minimum sewer diameter of 100 mm • a minimum tractive tension of 1 N/m2 • a minimum value for peak wastewater flow of 1.5 litre/second • This results in a minimum gradient of 1 in 200, and a 100 mm dia. sewer being able to serve 234 households of 5 people with a water consumption of 100 litres/ person day.

6. Comparative costs (1997 US$) of conventional and condominial sewerage in Parauapebas, Pará, north Brazil Source: Melo (2005).

7. Brasília Simplified sewerage in rich areas as well as in poor areas

8. CAESB, the water & sewerage company for Brasília and the Federal District, basically asked itself: If condominial sewerage works well in poor areas, shouldn’t it also work well in non-poor areas? Answer: Yes. The next question is: As condominial sewerage works well in both poor and non-poor areas, should we ever use conventional sewerage in urban housing areas?Answer: NO.

9. Waste stabilization ponds • Widely used in France (>2500 systems) and Germany (>3000) • France: Facultative pond (6 m2/p.e) + two maturation ponds (each 2.5 m2/p.e) • Research in UK: Facultative pond (as in France) + aerated rock filter (1 m2/p.e) − produces a very high quality effluent

10. Facultative and maturation ponds are GREEN because of the ALGAE that grow in them

11. Algal−bacterial mutualism Light New cells Algae O2 CO2 Bacteria New cells Wastewater BOD

12. Too cold for WSP in Europe? No! Québec

13. Chappelle Thouaroult, Brittany, France

14. Capital and O&M costs of various wastewater treatment processes for 1000 p.e. in France in 1998 Treatment Capital costs O&M costs process (€ p.e.–1) (€ p.e.–1 a–1) Activated sludge 230 11.50 Trickling filter 180 7.00 RBC 220 7.00 Aerated lagoon 130 6.50 Settler-digester + CW 190 5.50WSP 120 4.50

15. Small WSP system in Bavaria Village of Berg, near Munich (pop. ~250) Mean temp. of coldest month (Jan.): −2°C 1. Anaerobic pond

16. 2. Secondary facultative pond

17. Capital and O&M costs of various wastewater treatment processes for 500 p.e. in Germany in 1996 Treatment Capital costs O&M costs process (DM p.e.–1) (DM m–3) Activated sludge 2,000 2.00 Trickling filter 1,500 1.70 Aerated lagoon 1,200 1.70 Vertical-flow CW 1,200 1.50 Horizontal-flow CW 1,500 1.30WSP 700 1.20 Average 1996 exchange rate: DM1 = €0.53

18. P E R T H S H I R E Tigh Mor Trossachs WSP SCOTLAND Loch Achray

19. The effluent from a facultative pond loaded at 80 kg BOD/ha d complies with the UWWTD

20. (91/271/EEC)

21. Mat. pond Baffle → Rock filter Fac. pond Rock filter receiving maturation pond effluent – Veneta, Oregon

22. Suspended solids removal

23. BUT WinterResults foreffluent ammonia-N/l: Aerated RF: <2 mg/l Unaerated RF: ~8 mg/l Planted bed: ~7 mg/l SummerResults foreffluent ammonia-N/l: Aerated RF: <2 mg/l Unaerated RF: ~7 mg/l Planted bed: ~4 mg/l

24. Natural vs Conventional Wastewater Treatment • Basically a choice between LAND and ELECTRICITY: • Money spent on land is an investment • Money spent on electricity is money gone for ever $$$$$