Using biogas technology to solve the disposal issues surrounding latrine waste
Practical Action
Figure 2: Faecal Sludge Management Cycle - (Boot N. , 2007)
Possible Digester options
The aim of the digester is to provide a sealed vessel that allows input of feedstock and removal
of gas whilst being built of locally available construction materials.
The options of digester design are described in the Practical Action Technical brief Biogas.
The most common types of digester are the floating dome or Indian digester and the fixed
dome or Chinese digester.
Other digesters include the bag or balloon digester, a type of Plastic Bio-Digester and the plug
flow digester which is a type of Earth-pit plant. Both of these are more suitable in emergencies
or situations where a digester is needed quickly or only for a short period of time because of
their small life span in comparison to the above.
Assessing the technology
Technological barriers
The issues regarding technology can be split into collection, haulage, disposal and treatment.
Figure 3: A diagram explaining the problem of soiling up
Collection: the sludge will be partially degraded upon emptying therefore decreasing the
maximum methane yield. This means, to make the system feasible the frequency of pit
emptying will have to increase. Pit emptying frequency is inversely proportional to the
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