high-level policy dialogue on eu sanitation policies and practices in the 2008 international year of...

High-Level Policy Dialogue on “EU Sanitation Policies and Practices High-Level Policy Dialogue on “EU Sanitation Policies and Practices

in the 2008 International Year of Sanitation”in the 2008 International Year of Sanitation”

High-level low-cost High-level low-cost sanitation services in small sanitation services in small

towns and large villagestowns and large villages

Duncan MaraDuncan MaraUniversity of Leeds, UKUniversity of Leeds, UK

The Options:The Options:• On-site sanitation (e.g., pour-flush toilets + On-site sanitation (e.g., pour-flush toilets +

leach pits)leach pits)

• Low-volume flush toilets + Low-volume flush toilets + simplified sewerage + low-cost simplified sewerage + low-cost wastewater treatment (e.g., waste wastewater treatment (e.g., waste stabilization ponds)stabilization ponds)

Low-volume flush toiletLow-volume flush toilet

For example, For example, Swedish models Swedish models that use that use 3 litres3 litres per flush: per flush:

Simplified sewerageRigorous 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 This results in a minimum gradient of 1 in 200, and a 100 mm dia. sewer being in 200, and a 100 mm dia. sewer being able to serve 234 households of 5 people able to serve 234 households of 5 people with a water consumption of 100 litres/ with a water consumption of 100 litres/ person day.person day.

Comparative costs (1997 US$) of conventional and condominial sewerage

in Parauapebas, Pará, north Brazil

ItemConventional sewerage Condominial sewerage

Totalcost

Cost per connection

Totalcost

Cost per connection

Excavation 263,000 39 186,000 28

Inspection chambers

181,000 27 85,000 13

Sewers 185,000 28 102,000 15

Total 629,000 9494 373,000 5656

Source: Melo (2005).

Brasília

Simplified sewerage in rich areasas well as in poor areas

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.Answer: Yes.

The next question is:

As condominial sewerage works well in both As condominial sewerage works well in both poor and non-poor areas, should we ever use poor and non-poor areas, should we ever use conventional sewerage in urban housing conventional sewerage in urban housing areas?areas? Answer: Answer: NO.NO.

Waste stabilization pondsWaste stabilization ponds

• Widely used in France (>2500 systems) Widely used in France (>2500 systems) and Germany (>3000)and Germany (>3000)

• FranceFrance: Facultative pond (6 m: Facultative pond (6 m22/p.e) + two /p.e) + two maturation ponds (each 2.5 mmaturation ponds (each 2.5 m22/p.e)/p.e)

• Research in UKResearch in UK: Facultative pond (as in : Facultative pond (as in France) + aerated rock filter (1 mFrance) + aerated rock filter (1 m22/p.e) − /p.e) − produces a very high quality effluentproduces a very high quality effluent

Facultative and maturation ponds Facultative and maturation ponds are GREEN because of the are GREEN because of the ALGAEALGAE

that grow in themthat grow in them

Algal−bacterial mutualism

Algae

Bacteria

O2 CO2

New cells

New cells

LighLightt

Wastewater BOD

Québec

Too cold for WSP in Europe? No!No!

Chappelle Thouaroult, Brittany, France

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 5.50 WSP 120 4.50

1. Anaerobic pond1. Anaerobic pond

Small WSP system in Bavaria

Village of Berg, near Munich (pop. ~250)Village of Berg, near Munich (pop. ~250)Mean temp. of coldest month (Jan.): −2°C

2. Secondary facultative pond2. Secondary facultative pond

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 1.30 WSP 700 1.20Average 1996 exchange rate: DM1 = €0.53

PERTHSHIRE

SCOTLAND

Loch Achray

Tigh Mor Trossachs WSP

The effluent from a facultative pond loaded at 80 kg BOD/ha d

complies with the UWWTD

(91/271/EEC)

Rock filter receiving maturation pond effluent – Veneta, Oregon

Fac. pond

Mat. pond

Rock filter

Baffle →

Suspended solids removal

Summer Results for

effluent ammonia-N/l:

Aerated RF: <2 mg/l

Unaerated RF: ~7 mg/l

Planted bed: ~4 mg/l

BUT Winter Results for

effluent ammonia-N/l:

Aerated RF: <2 mg/l

Unaerated RF: ~8 mg/l

Planted bed: ~7 mg/l

Natural vs Conventional Wastewater Treatment

Basically a choice between LAND Basically a choice between LAND and ELECTRICITY:and ELECTRICITY:

• Money spent on land is an Money spent on land is an investmentinvestment

• Money spent on electricity is Money spent on electricity is money gone for evermoney gone for ever