Feedstock

The following products can be used as feedstocks (sometimes referred to as substrate) for anaerobic digestion.

• Food processing and abattoir waste.

• Source-separated biowaste.

• Mechanically-separated municipal waste.

• Commercial catering waste.

• Sewage sludge.

• Animal slurry.

• Energy crops.

The food waste chain shows that all waste that is produced from the production of food, from the farm to the retail outlet and finally the household can be anaerobically digested (excluding Specified Risk Material (SRM)).   The nutrients within the biofertiliser resulting from all the waste can be recycled back onto the farmland to complete the chain and the biogas can be used to produce renewable energy.

These products can be digested on their own as a single feedstock. However, a process that is dealing with only one feedstock, e.g. maize, is likely to be more susceptible to changes in climatic conditions, or changes in feedstock quality or quantity, compared to a process that is co-digesting several feedstocks.   Co-digestion ensures that there is a greater variety of bacteria within the feedstock and therefore within the digesters bacterial population, creating a more robust and stable process.