Anaerobic digestion is a complex biological process involving the breakdown of organic matter in the absence of air in large, sealed and insulated vessels with controlled heating and mixing.
Food waste enters a sealed building where it is processed into a liquid porridge, and then pumped into temperature controlled sealed vessels known as digesters. It is here that bacteria feed on the food waste and produce biogas. Biogas is typically made up of 60% methane and 40% carbon dioxide and is captured and used as a fuel in CHP engines.
The digestate or biofertiliser produced undergoes pasteurisation to ensure that any pathogens are killed and is stored in large lagoons ready to be applied twice a year on farmland. The use of this high nutrient biofertiliser replaces the use of fossil-fuel derived fertilisers and ensures a complete loop of carbon and energy capture.
Each tonne of food waste recycled by anaerobic digestion as an alternative to landfill prevents between 0.5 and 1.0 tonne of CO2 re-entering the earth’s atmosphere.