METHOD FOR TREATING CO2-CONTAINING WASTE GAS AND ITS APPARATUS

PURPOSE:To use CO2 for methane fermentation effectively to obtain energy efficiently and suppress the increase of CO2 concentration in air bar leading CO2 in waste gas to raw material liquids for methane fermentation consisting of organic raw materials and methane bacteria. CONSTITUTION:Passing through a duct 3, CO2-containing waste gas is led to water in a water tank 5 by pressure and the CO2 in the waste gas is dissolved in the water. Meanwhile, raw materials for methane fermentation consisting of finely crushed organic raw materials, water, and methane bacteria-containing sludge of night soil or sewage excess sludge and supplied through a pipe 9 for supplying raw materials for methane fermentation are kept in anaerobic conditions at a prescribed temperature in a fermentation tank 8 to carry out methane fermentation. The aqueous CO2 solution in the water tank 5 is sent to this fermentation tank 8 and mixed with them. Consequently, the fermentation of the raw material liquid for methane fermentation in the fermentation tank 8 is greatly accelerated by the function of the CO2, so that efficient methane fermentation is carried out and the methane gas generation amount is increased and the generated methane gas is taken out of a methane gas extraction pipe 10 and used as a fuel.