Tuesday, 26 May 2009

Local radio advocacy

Here’s a heartening story from India on the BBC News site yesterday: Radio boost for marginalised women. It seems to me that this kind of initiative could easily be adopted for water and sanitation advocacy to support CLTS and India’s Total Sanitation Campaign (of the 1.2 billion open defecators in the world in 2006 over half − 56% − live in India).

Wednesday, 13 May 2009

EcoSan again ...

I’ve just been reading Study for Financial and Economic Analysis of Ecological Sanitation in Sub-Saharan Africa − Final Synthesis Report produced by Hydrophil and Atkins (April 2009). It compares the costs (in net present value terms) of VIP latrines, EcoSan toilets and conventional sewerage in urban areas in Burkina Faso, South Africa and Uganda. It’s interesting but it doesn’t attempt to estimate the costs of simplified sewerage. However, there are some cost data from South Africa in Sanitation for a Healthy Nation: Sanitation Technology Options (DWAF, 2002), which gives capital costs of ZAR 600−3000 for single-pit VIP latrines, ZAR 3000−4000 for eThekwini latrines, ZAR 2500−3000 for simplified sewerage, and ZAR 6000−7000 for conventional sewerage. [If you lived in a high-density low-income urban community in South Africa, which would you choose?]

So we can’t conclude much, if anything, from the Hydrophil/Atkins report about what are the best sanitation options in low-income high-density urban areas in Sub-Saharan Africa − and that’s a real pity.

Tuesday, 5 May 2009

Rio de Janeiro

I spent last Saturday looking at low-cost sewerage schemes in the state of Rio de Janeiro with my good friend (and colleague for over 25 years) Augusto Sérgio Guimarães. We went to the town of Paracambi, located in the flat lands just below the mountains separating the states of Rio and São Paulo − so the well-known orographic effect is active and, when it rains, it rains very heavily and parts of the town often become flooded. Two solutions were tried. One was to collect the all the wastewater discharges into the local stream in a sanitary sewer running along one side of the stream (all the discharges were on this side), treat the wastewater in a septic tank and anaerobic filter, the effluent from which went into the stream; stormwater continued to be discharged directly into the stream − not necessarily the ‘best’ solution but certainly a ‘good’ one and at least the stream wasn’t receiving totally untreated wastewater any more. The other was an innovative low-cost combined sewerage scheme: both domestic wastewater and stormwater go into the same sewer and into a septic tank and anaerobic filter (with the effluent going into the stream), but during intense rain the septic tank and anaerobic filter are by-passed and the combined wastewater goes directly to the stream.

In one part of Paracambi we also saw something else very interesting: a badly designed conventional sewerage scheme. Why badly designed? Well, it was designed only for domestic wastewater but most households (which had no problems before the scheme was put in) discharge rainwater from the roofs into the sewer − so, when it rains, the sewers overflow into the street! Hardly an improvement. The engineers who designed the scheme just hadn’t realised what the householders were doing and so, in ignorance, designed a scheme which simply made matters worse. A lesson for all of us: work with the people and take the local situation into account.

Friday, 1 May 2009

Waste stabilization ponds

Well, this week I’ve been in Belo Horizonte, the capital of the state of Minas Gerais in Brazil, at the International Water Association’s international specialist conference on waste stabilization ponds − a low-cost but highly efficient way to treat wastewater (details here). What a week! Very good conference, very good crowd of people (some of whom I only meet at these events, so it’s good to catch up with them), and excellent Brazilian food! Wastewater treatment is part of sanitation − if you have low-cost sewerage, you need low-cost wastewater treatment, and waste stabilization ponds are the best way to treat wastewater at the least cost. You can collect the biogas from anaerobic ponds and generate electricity (and maybe earn some carbon credits). It’s also possible, although more difficult and more expensive, to harvest the algae from high-rate algal ponds and make algal biodiesel − but this is likely to take a decade or two before it’s commercially viable.