Enhancing Production of Adapted Bacteria To Degrade Chlorinated Aromatics

Abstract

The study's aim was to enhance the production of adapted bacteria for degrading chlorobenzene (CB) and o-dichlorobenzene (DCB). Batch cultures fed by pulses of substrate (SPB, substrate pulse batch process) were successfully performed in a 12-L bioreactor: 240 mg L-1 h-1 of CB/DCB mixture was eliminated, and 50 mg L-1 h-1 of dry weight was produced. Studying the substrate removal dynamics, the concentration of metabolic intermediates and chlorides, and the cellular integrity allowed the correct proceeding of bacterial cultivation. The substrate loading rate was optimized to obtain the highest biomass productivity with the lowest toxicity and inhibiting effects. The time interval between each pulse was decreased gradually so that a continuous substrate feeding was finally attained. In the continuous feeding technique, both cell productivity and CB/DCB elimination capacity were twice the values obtained with the SPB. Results come up to industrial prospects and present the continuous feeding technique as an attractive adaptation of SPB to degrade chlorinated solvents.