Draft PPS18: Renewable Energy
Annex 1 Energy from Waste (Biological Processes) Technology: Digestion Equipment
C22. An anaerobic digestion plant typically comprises a digester tank, buildings to house ancillary equipment such as a generator, a biogas storage tank, a flare stack and associated pipework. Plants can vary in scale from a small scheme treating the waste from an individual farm, or a medium-sized centralised facility dealing with wastes from several farms, to a sizeable industrial plant handling large quantities of MSW.
C23. Digestion takes place in a tank, which is usually cylindrical or egg-shaped. The size of the tank will be determined by the projected volume and nature of the waste to be handled and the temperature and retention time in the digester. Some indicative tank dimensions are given in table 1. Digesters with a volume of less than 250m3 can operate successfully on farms. Whereas most tanks are constructed from glass-coated steel, these small digesters are often made of glass fibre-reinforced plastic.