for a sustainable and better future   



for a sustainable future.

for a sustainable future.

Digestate PDF Print E-mail


At the end of the anaerobic digestion process there is a useful residue also called the digestate, containing fertiliser and fibre.


All N, P and K remain available in the digestate as none is required to make methane or carbon dioxide. The amount of nutrient varies considerably in each digestate depending primarily on the feedstock and dry matter content. It is also well known as a slow release fertiliser as the long chain compounds retain the nitrogen to be used by growing plants instead of being washed away into watercourses.


The fibrous (solid) part of the digestate may be separated: with or without significant amounts of nutrients. This makes transport and storage more manageable.
The high nutrient fibre can be stored in a stack in a field saving storage costs. The solid fibre digestate is not subject to the closed period regulations enforced by the Nitrates Directive whereas the liquid digestate is. Whilst using 10 to 15% of the volume of the storage requirement over liquid digestate.
Dry fibre fraction of the digestate (with little or no nutrients) can be used either as a fuel or bedding for animals. Using heat from the CHP generator the bedding or fuel can be produced at a cost significantly below the current market price for solid fuel (€75-€150 per tonne).
Agricultural demand for bio-fertiliser, the nutrient-rich-fertiliser and soil conditioner that is produced when quality bio-degradable waste are treated via anaerobic digestion (AD), has recently received a boost in the UK thanks to the recent launch of BSI PAS110 – the new voluntary national quality specification for bio-fertiliser.

Each country has its own legislation on fertilisers. In every country to use the residue as a fertiliser always requires approval from the authorities.

The use of the process residue is the third major advantage of anaerobic digestion.

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