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< prev - next > Water and sanitation Sanitation KnO 100493_Using biogas technology to solve disposal issues of latrine waste (Printable PDF)
This technical brief looks at the option of using biogas
units to reduce the waste produced by standard pit
latrines. Waste is removed from the pit and transported to
a biogas system where treatment takes place.
As populations grow and urban migration places further
strain on towns, problems surrounding the applicability of
on-site sanitation facilities such as pit latrines (Figure 1)
and how they were originally supposed to operate are
Using a pit to retain the faeces underground for
approximately two years making it less harmful requires
space, which densely populated regions such as slum
areas do not have, and there are cost implications of
repeated construction.
Therefore users must empty their latrines and reuse them
whenever possible. This has been the subject of much
research over the past few years, but what is then done
with the emptied waste has received little attention.
Figure 1: Pit latrines in the
The need to collect sludge from an on-site system,
Kibera informal settlement
transport it to a treatment facility and dispose of it
(slum) in Nairobi, Kenya. Photo:
hygienically was given the term Faecal Sludge
Karen Robinson / Practical Action.
Management (FSM) by the Department of Water and
Sanitation in Developing Countries (SANDEC) in Switzerland. Figure 2 shows that the first
step to solving disposal issues is to implement a structured procedure that defines how waste
should be managed. Without it pollution of the environment will occur earlier (i.e. during a
transportation stage).
Biogas technologies
Biogas is the by-product of anaerobic digestion, the breaking down of organic material in the
absence of air. The gas is rich in methane and can be used as a fuel for cooking, lighting and
generating electricity. Anaerobic digestion takes place in what is known as a digester.
Traditionally digesters have been directly linked to the latrine so the fresh faeces are subjected
to digestion immediately. Little work has been done to see if using mature, partially digested
waste from a pit latrine is feasible in producing biogas.
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