Removal kinetics of acetone and MIBK from a complex industrial wastewater by an acclimatized activated sludge

Removal rates of acetone and methyl isobutyl ketone (MIBK) were determined singularly and in combination in batch experiments employing an acclimatized activated sludge from a pilot system treating an organic chemical manufacturer industrial wastewater, as well as during the course of operation of the pilot system. Both acetone and MIBK removals were described by first-order removal kinetics. Acetone, as a single substrate, was biodegraded at a rate of 1.7 day−1. MIBK was biodegraded, during the single-substrate experiments, at an observed rate of 2.23 day−1. Relative to the control (no spike) experiments, acetone removal was augmented by a factor of 3 during the acetone spike, with an observed biomass-specific removal rate of 0.0023 L/mg VSS day. MIBK removal during an MIBK spike was also enhanced by a factor of 2, and the greatest biomass-specific removal rate of MIBK was observed during the acetone spike of 0.0019 L/mg VSS day. The observed rates were approximately 3 orders of magnitude greater than the observed rates in the pilot scale system. MIBK exerted a synergistic effect on the acetone-removal rate while acetone exerted an inhibitory impact on the MIBK-removal rate.