Anaerobic fermentation to produce biogas

摘要

A process and apparatus for the anaerobic digestion of organic wastes, preferably to also produce a useful biogas, is described. The waste may have a total solids (TS) concentration of 6% or less while a digester is operated at a higher solids concentration, for example with a feed TS concentration of 8-12%. One or more separation stages downstream of the digester separate active bacteria and undigested organics from the digestate, and return separated matter to the digester. Optionally, a feed thickening apparatus and step may be provided upstream of the digester. The upstream thickener and recycle from the downstream separation stages are operated such that the TS of the combined inputs to the digester is within a desired range.

主权项

1. A process for the treatment of a liquid comprising organic material, the process comprising steps of, anaerobic digestion of the liquid to produce a digestate; separating solids from the digestate in two or more sequential separation steps wherein an upstream one of the two or more sequential separation steps comprises separating particles above a first size and a downstream one of the two or more sequential separation steps comprises separating particles above a second size that is smaller than the first size and wherein the upstream one of the two or more sequential separation steps provides a coarse separation of materials that are difficult for anaerobic bacteria to digest.