Anaerobic digester technology

Abstract

The anaerobic, displacement-type digester is for the biological production of methane gas. The process involves the anaerobic digestion of solid waste and water or a sewage slurry to produce a methane-rich gas, which can be utilized for its energy value. The digester includes a tank-type enclosure comprising an input end, a digesting chamber and an output end. At the output end a sealable output chamber is provided which can separate the output end from the digesting chamber. The output chamber is comprised of a lower partition and an upper partition, which allows the output chamber to be sealed from the digesting chamber. As waste material is introduced at the input end of the digester, a slurry is formed. The upper stratum of material or scum must periodically be removed from the slurry to provide space for additionally introduced waste into the digester and to optimize the anaerobic digestion process. An upper stratum displacement means is provided at the digesting chamber of the digester. The displacement means removes the upper stratum of material over the lower partition into the output chamber. When the level of material in the output chamber rises to emerge the bottom of the upper partition a seal is formed between the output chamber and the digesting chamber. This seal allows the scum material to be removed from the output chamber without excessive loss of methane gas from nor introduction of air into the digesting chamber of the digester.