BACTERIAL CELL RETURNING OPEN TYPE ACIDIC FERMENTATION TANK IN TWO-PHASE TYPE METHANE FERMENTATION APPARATUS

摘要

PURPOSE: To prevent the deterioration of a separated liquid quality excessive in ammonia by holding the pH of an open type acidic fermentation tank held its liquid temp. near to a specific temp. within a specific range and propagating substrate-decomposing bacteria such as yeast or koji (malted rice) to digest a substrate and returning excessive bacterial cells becoming excessive due to the continuation of propagation by bacterial cell return devices. CONSTITUTION: Cooling water cooled by a cooler 4 is sent to a heat exchanger 3 to hold the liquid temp. in an open type acidic fermentation tank 1 to about 36 deg.C and air is sent to an air supply port 8 attached to the lower part of a stirrer 9 from an air sending device 5 through a bacteria removing filter 6 and a bacteria free air sending pipe 7 to perform aeration stirring. Further, sulfuric acid is added from a pH adjusting device 10 to hold the pH of the open type acidic fermentation tank 1 to 3.5-4.5 and substrate decomposing bacterial such as yeast or koji are propagated to digest a substrate. Excessive cells becoming excessive due to the continuation of propagation are returned by bacterial cell return devices 13-15 to perfectly eliminate excessive yeast sludge. By this constitution, the deterioration of a separated liquid quality caused by excess ammonia can be prevented and post-treatment is enabled.