EFFECT OF GLUCOSE ON 2,4-DINITROPHENOL DEGRADATION KINETICS IN SEQUENCING BATCH REACTORS

A Janthinobacterium sp. and a Rhodococcus sp., both capable of mineralizing 2,4-dinitrophenol (DNP), were used as inoculum for activated sludge in bench-scale sequencing batch reactors (SBRs). Degradation of 10 mg/L of DNP in these SBRs was enhanced to varying degrees by the addition of glucose at concentrations of 50, 1 00, and 500 mg/L. Addition of 10 mg of glucose/L had no effect, while 1000 mg of glucose/L inhibited DNP degradation. Maximal degradation, based on the rate of DNP degradation per unit of glucose added, was obtained at a glucose concentration of 100 mg/L. A Michaelis-Menten type saturation rate model was successfully used to model DNP degradation kinetics in the SBRs; comparison of model parameters then allowed us to determine the effect of glucose addition. Also, it was found that the added glucose was associated with an increase in the standing biomass of DNP-degrading bacteria, probably because of greater retention of this population in the activated sludge. This research demonstrates the usefulness of supplemental carbon substrates for enhancing the degradation of toxic chemicals in bioreactors containing heterogeneous microbial communities.