Biodigestion (also called anaerobic digestion or AD) operates in the absence of oxygen, usually in a sealed contained area. Bacteria decompose the organic matter, producing biogas (methane and carbon dioxide) that can be captured to produce energy.
After the leftover liquid (leachate) is removed, it can be processed into fertiliser. The finished solid matter (digestate) is a productive soil enhancer. It can also be added to a compost system as a starter or to further minimise pathogens by putting the matter through a second process.