A facility in which biogas is produced from biological waste by anaerobic digestion. In large tanks, called digesters, anaerobic digestion takes place in the absence of oxygen, in which micro-organisms break down organic matter to produce methane, carbon dioxide and other gases that form biogas. The feedstock can be organic waste, manure or sewage. The biogas produced is collected, dried and purified of unwanted impurities (e.g. sulphur dioxide) and further used for heat and electricity production. The processed waste is concentrated and used as fertiliser.