Method for treatment of a discharge liquid produced in treatment of an exhaust gas

摘要

A process for treating an exhaust gas discharged from a coal combustion apparatus, in which the exhaust gas is first led to a dry type dust collecting device, and after fly ash in said exhaust gas is removed, said exhaust gas is treated by a wet type exhaust gas cleaning device; a part of said fly ash collected in said dry type dust collecting device is added to a discharge liquid or a discharge sludge discharged from said wet type exhaust gas cleaning device. The amount of the fly ash to be added to the discharge sludge should be at least three times (in weight) as much as the amount of water contained in said discharge sludge. Preferably fly ash of approximately the same weight as that of said discharge sludge should be added to the discharge sludge discharged from said wet type exhaust gas cleaning device, and subsequently calcium hydroxide of about one-tenth in weight of said discharge sludge should be added to the mixture for solidifying said discharge sludge. In a preferred embodiment, the mixture of the discharge liquid and the fly ash is led to a solid-liquid separator to separate the mixture into clear water and sludge, and the clear water is returned to said wet type exhaust gas cleaning device, while the separated sludge is mixed with additional fly ash to further eliminate a discharge water.