Feasibility Study for a National Domestic Biogas Programme in - SNV

Feasibility Study for a National Domestic Biogas Programme Burkina Faso
appropriate feeding practices and sleeping boxes. All these paddock components
could be incorporated into existing stable design currently being promoted by various
livestock projects. However it is not a must to have the stable modified to
sophisticated designs, but if convenience in digester feeding is a priority such
solutions may be required, and of course will come at a price.
A biogas unit with a good stable design should never require fresh water to feed the
digester. The urine and the collected household waste water should be sufficient to
dilute the dung.
Also in ‘craals’ where cattle are kept over night improved floors could be installed.
Instead of a concrete floor, concrete tiles (15*15*4.5 cm) could be used to pave the
kraal.
Other parts of the unit are support, advice or measures to enhance the utilization of
the effluent as fertilizer. Also here the approach should be guided by a key element:
convenience. As the effluent is in liquid form, its transportation is cumbersome. As
farming systems generally require organic fertilizer to be available in bulk at one time
of the year, storage pits or compost heaps will be needed for the overflow. Therefore,
wherever possible, the liquid overflow should be guided by gravity to the sealed
composting pit where it is mixed with lignin rich unshredded plant waste. Such
channels should be sidelined by fodder grass which picks up the nutrients leaching
into the soil in those channels. Thus the otherwise lost nutrients can immediately
encourage the internal nutrient cycle of the farming system.
Other options are to use the overflow in its liquid form as much as possible near the
house. This will lead to good crops in the vegetable gardens or in the fields
neighbouring the biogas plant.
b) The minimization of water and maximization of urine as a mixing agent
In all cases the effort required to supply the biogas plant with water should be
minimized or avoided where possible.
A direct collection from the stable floor makes the minimization of water utilization
possible. On the overflow side the moisture component should be recovered in form
of providing the moisture to plant roots. The same chamber can be used to collect
the grey water from kitchen, showering and washing.
An additional option for the unit approach was developed by the Nepal Biogas Sector
Partnership (BSP) 97 : rainwater harvesting tanks with a capacity of 2 to 6m³ are
implemented at farmer household level. A similar system exists already in Burkina
Faso in Fada N’Gourma and could be extended to biogas users.
c) Offering a toilet connection 98
Given the sanitation coverage in Burkina Faso, offering a toilet in connection wit a
biogas plant could be of great importance for market penetration. A comfortable toilet
is the central part of a sanitary biogas unit. Biogas septic tanks are designed as an
integrated fixed dome biogas plant. Sanitary aspects, for example a clean toilet with
low maintenance costs, could be more important than high gas production.
97 RAIN newsletter June 2006, Rainwater Harvesting Implementation Network (RAIN), Amsterdam, The Netherlands,
www.rainfoundation.org
98 Ludwig Sasse, Christopher Kellner, Ainea Kimaro, Improved Biogas Unit for Developing Countries, GATE inGTZ,
1991
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