Anaerobic digestion with supercritical water hydrolysis as pretreatment

摘要

An hydrolysis stage of an anaerobic digestion (AD) process includes supercritical treatment in a reactor (R1). The treatment may use sub-stoichiometric oxygen so that there is not full oxidation. Effluent from the supercritical treatment may be used to pre-heat the organic matter in-feed to the supercritical treatment. There may be a second supercritical treatment in a second reactor (R2). This may have full stoichiometric oxygen, to oxidize the solids from the first reactor (R1) effluent. Furthermore, it provides heat for pre-heating its own in-feed and also that for the first reactor (R1). The output from the hydrolysis may be only clarified liquid, leading to particularly efficient downstream AD processes. The second supercritical treatment rector may oxidize also fed-back solids from the final stage of the AD.

主权项

1. A process for anaerobic digestion of moisture containing organic matter, the process comprising the steps of hydrolysis, acidogenesis, and methanogenesis, wherein the hydrolysis step comprises supercritical treatment of the organic matter having a moisture content of greater than 70%, in a first supercritical reactor by elevation of the organic matter to a temperature of at least 374° C. and a pressure of at least 221 bar for a supercritical residence time in the range of 60 s to 180 s, wherein an oxidant is introduced at a sub-stoichiometric level for the supercritical treatment, and wherein the supercritical treatment provides an effluent and said effluent is delivered to a venting vessel from which gases are recovered, and at least some of said effluent is delivered to said acidogenesis step.