GAS TREATMENT METHOD, AND GAS TREATMENT APPARATUS

PROBLEM TO BE SOLVED: To prevent formation of thermally stable salts of amines by oxygen in a mixed gas, and to effectively utilize ammonia contained in waste water.SOLUTION: A gas treatment method removes hydrogen sulfide in a gas by using an absorption tower 10 to absorb hydrogen sulfide using an absorption liquid, and at least one stripping tower 20 to separate ammonia or hydrogen sulfide from waste water containing hydrogen sulfide and ammonia. The gas treatment method includes: a step of bringing a mixed gas of combustible gases, hydrogen sulfide and oxygen into contact with ammonia-containing water as the absorption liquid and neutralizing hydrogen sulfide by ammonia in the absorption tower 10, and releasing the mixed gas whose hydrogen sulfide content has been reduced to the outside; a step of heating the absorption liquid having absorbed hydrogen sulfide together with the waste water in the stripping tower 20, and releasing hydrogen sulfide gas from the absorption liquid having absorbed hydrogen sulfide and the waste water; and a step of supplying a part of a reflux of the stripping tower 20 to the absorption tower 10, as an absorption liquid.