KINETICS AND MODELING OF HEXAVALENT CHROMIUM REDUCTION IN ENTEROBACTER-CLOACAE

Kinetics of bacterial reduction of toxic hexavalent chromium (chromate: CrO42-) was investigated using batch and fed-batch cultures of Enterobacter cloacae strain HO1. In fed-batch cultures, the CrO42- feed was controlled on the basis of the rate of pH change. This control strategy has proven to be useful for avoiding toxic CrO42- overload. A simple mathematical model was developed to describe the bacterial process of CrO42- reduction. In this model, two types of bacterial cells were considered: induced, CrO42--resistant cells and uninduced, sensitive ones. Only resistant cells were assumed to be able to reduce CrO42-. These fundamental ideas were supported by the model predictions which well approximated all experimental data. In a simulation study, the model was also used to optimize fed-batch cultures, instead of lengthy and expensive laboratory experiments.