A Brief Introduction to the Biodigester
A Brief Introduction to Simplified Sewerage
Having access to safe sanitation means fewer deaths from water-related diseases, equality and dignity. In Tanzania 90% of people lack access to adequate sanitation, with the vast majority of these relying on pit latrines.
Pit latrines are unsafe and unhygienic: the most common method for emptying them is uncovering them during the rainy season so that waste fills the streets ‘where children play, women cook and the busy bustle of everyday life occurs’.
The lack of adequate sanitation means that the city faces a persistently high environmental disease burden. The negative health impact in turn causes negative effects on social and economic development. The Tanzanian government itself loses an estimated US$206million per year due to poor sanitation (WSP, 2012).
Charcoal is used for cooking by an estimated 90% of the population across Tanzania and Sub-Saharan Africa (World Future Council, 2015). This dependence on charcoal has major problems: it drives widespread deforestation across Africa and has significant health impacts for those who use it.
Rapid urbanisation means that both of these crises will only get more severe.
CDI and our partners have shown that simplified sewerage is a fresh and innovative solution to the sanitation crisis. It is widely used across Latin America and Pakistan, but never before in Tanzania.
What is it?
Over the course of the three summer projects the CDI WaSH project has:
The CDI WaSH project aims to offer biogas as a renewable alternative to charcoal for local urban communities, by producing it from human waste. A biodigestor turns the waste collected by the sewerage network into biogas in an anaerobic digestion process, which occurs naturally in waterlogged conditions. CDI are also piloting a new EvapoDryer technology, to evaporate water from the digested material - sewage sludge effluent - in order to remove dependence on waste stabilisation ponds and produce biofertiliser.
CDI began pairing simplified sewerage networks with biogas generation in 2015, using a biodigestor produced by SOWTech, a UK-based Community Interest Company. Having produced burnable biogas with the SOWTech digestor, CDI are looking to transition to a Tanzanian supplier to ensure long-term sustainability via a social franchise whereby profits generated through biogas and biofertiliser sales are invested in building new simplified sewerage networks.