Anaerobic Digestion

Anaerobic Digestion is not a new process; it has been practiced by people throughout the ages to fuel their stoves. In the UK today, most sewage plants use AD to treat Sewage Sludge.

Anaerobic Digestion is an essential process of nature. For anyone who feeds dairy cows the chemistry is relatively straightforward. Picture a normal cow. The process flow is: Feed in -> Fermentation to short chain fatty acids in the rumen -> convert to milk/meat -> Waste out.

Specialist companies are seeking farms to set up large scale AD plants and ratios of 3:1 food waste to slurry have been suggested but disposal of the effluent left requires the farmer partner to provide a large land area.

Side Benefits

The maceration and mechanical working during digestion creates a much more uniform slurry which is easier to spread. If it is dewatered and dried it can make a useful organic fertilizer.

For the farmer there is a reduction in weed seeds in the slurry and a marked reduction in smell - the latter could make AD attractive for village farmers.

What is the tangible financial return?

It would be misleading to quote 'standard' numbers; because AD output is affected by what goes in, each case must be considered on its merits. The electricity value of the energy created depends on whether the generating farmer consumes his own electricity, in which case it is valued at the 'retail' price or, whether they are selling back to the grid.

If you require any more information on Anaerobic Digestion please contact:

George Jardine
Renewables Energy Manager
CMS UK
Spring Farm Business Centre
Moss Lane
Minshull Vernon
Crewe
Cheshire CW1 4RJ
Tel: 01270 522645