An odor control system and method for removing unwanted odorous airborne constituents in which the gas stream is flowed through a compact, boxlike housing having a plurality of sequentially communicating treatment chambers. Gas stream pretreatment is accomplished in a first chamber, in fluid communication with a sump, as the gas flows through a packed bed wetted by suitable chemical reagents. After pretreatment, the gas stream is passed through downstream chambers, also utilizing wetted packed beds. These chambers are in fluid communication with a second, separate sump. Because of the first chamber/separate sump combination, influent gas treatment, by stages, can be accomplished. In this manner, different, contemporaneous chemical treatments are possible, within the single housing, with different chemical reagents utilized as needed. Such treatments are possible even in cases where otherwise incompatible chemical reagents are used. Reagents used in the first chamber are, in substantial part, recycled from the blowdown of the first chamber sump which can be augmented, if desired, by unreacted chemicals in the blowdown of the downstream sump. After treatment in the last downstream chamber, the cleaned gas flows through a demister, for moisture removal, before it is exhausted to atmosphere.

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