Modeling of 1,2-Dichloroethane Biodegradation byXanthobacter autotrophicus GJ10 under Shock Loading of Other Halogenated Compounds in Continuous Stirred Tank Bioreactor

A mathematical model describing the behavior of a continuous culture that degrades 1,2-dichloroethane and receives a shock loading of another compound was developed. The model takes into account possible cell death due to toxicity, growth inhibition and additional growth of cells on the second carbon source. Biodegradation is coupled to cell growth on the additional carbon source or by incomplete and unproductive degradation. The model was tested with Xanthobacter autotrophicus strain GJ10 growing on 1,2-dichloroethane in a continuous stirred tank bioreactor. Dichloromethane, dibromomethane, 1,2-dibromoethane, monofluoroacetate, monochloroacetate and monochloroacetic acid were added separately in the form of a pulse. The effects that were observed varied from low toxicity in case of dihalomethanes and chloroacetate up to severe cell death followed by culture washout in the case of monofluoroacetate and 1,2-dibromoethane. The experimental profiles were in most cases satisfactorily described with the proposed model.