Digestate and Biogas Cleaning and Processing

Through anaerobic digestion, raw biogas is produced. This contains significant amounts of energy-containing methane, but the proportion is much lower than natural gas. In order to allow biogas to be used in specific systems, the raw biogas must be cleaned of impurities, and in some cases upgraded to bio-methane (a renewable natural gas equivalent). In addition, the digest produced from anaerobic digestion, although energy-depleted, has high levels of nutrients that can be beneficially used as a fertiliser. In order to use digestate as a fertiliser, a variety of treatments may be required to prevent hazards. In this chapter, the cleaning of the digestate and raw biogas produced in anaerobic digestion are outlined and discussed.