COD reduction kinetics in a biological batch reactor: effect of impeller submergence and speed

Abstract

Impeller design and operation are important factors in the performance of an agitated biological reactor. Agitation enhances the mass transfer coefficients of various substances required for the system. In the present study experiments were conducted to assess the effect of impeller submergence and speed on the COD reduction in a batch reactor of size 450 mm × 450 mm × 1070 mm with working volume 154 dm 3. Results indicate that chemical oxygen demand (COD) reduction decreases with increase in impeller submergence and increases with increase in impeller speed up to 100 rev min −1, after which there is no substantial change in COD reduction. Mathematical models correlating COD reduction with impeller speed and submergence have been developed.