The principle layout of a farm-scale agricultural biomethanisation plant is quite simple. Manure is collected in a reservoir near the digester, from which the digester is fed by a pump. The temperature can be either mesophilic with about 35° C or thermophilic with about 55° C.
The digester has an agitator which mixes the digester's contents. The average hydraulic retention time of the manure inside the digester is 10-20 days. During this time the organic substances in the manure are metabolized by the microorganisms. Two different outputs are biogas and digested substrate. The latter is stored in a standard manure storage tank.
The biogas is stored in a gas storage tank from which there is continuous supply to a gas or diesel gas engine where heat and electricity are produced. |
