METHOD FOR PRODUCING METHANE GAS FROM GARBAGE USING THREE-STAGE METHANE FERMENTATION SYSTEM

摘要

PURPOSE: Provided is a method for producing methane gas from garbage using three-stage methane fermentation system, which can produce a large quantity of methane gas with low HRT and a small reactor. CONSTITUTION: The method comprises the steps of a hydrolysis/acid fermentation step in which crushed garbage by a crusher (A) is mixed with water at the ratio of 1 to 1, and then conveyed to a hydrolysis/acid fermentation tank (B) wherein hydrolysis is carried out by aerobic bacteria and acid fermentation is carried out anaerobic bacteria in the condition of 28 to 32 deg.C of reaction temperature and pH range of 5.0 to 5.5; a primary acid fermentation step in which pretreated admixture of garbage and water is conveyed to the bottom part of a UASB (Upflow Anaerobic Sludge Blanket) type primary acid fermentation tank (C) by a pump (P), and then seeding thereto Clostridium butyricum for increasing yield rate of acetic acid and butyric acid in the condition of 33 to 37 deg.C of reaction temperature and pH range of 5.0 to 5.5; a methane fermentation step in which only liquid obtained during the primary acid fermentation step is conveyed to a methane fermentation tank (D) through a pipe installed up to middle part from upper part of the primary acid fermentation tank so that the conveyed liquid is fermented. The methane fermentation step is performed in the condition of 7.6 to 7.9 of pH range and 39 to 43 deg.C of reaction temperature.