Evaluation of 4-bromophenol biodegradation in mixed pollutants system by Arthrobacter chlorophenolicus A6 in an upflow packed bed reactor

Bromophenol is listed as priority pollutant by U.S. EPA, however, there is no report so far on its removal in mixed pollutants system by any biological reactor operated in continuous mode. Furthermore, bromophenol along with chlorophenol and nitrophenol are usually the major constituents of paper pulp and pesticide industrial effluent. The present study investigated simultaneous biodegradation of these three pollutants with specially emphasis on substrate competition and crossed inhibition by Arthrobacter chlorophenolicus A6 in an upflow packed bed reactor (UPBR). A 2³ full factorial design was employed with these pollutants at two different levels by varying their influent concentration in the range of 250–450 mg l^?1. Almost complete removal of all these pollutants and 97 % effluent toxicity removal were achieved in the UPBR at a pollutant loading rate of 1707 mg l^?1 day^?1 or lesser. However, at higher loading rates, the reactor performance deteriorated due to transient accumulation of toxic intermediates. Statistical analysis of the results revealed a strong negative interaction of 4-CP on 4-NP biodegradation. On the other hand, interaction effect between 4-CP and 4-BP was found to be insignificant. Among these three pollutants 4-NP preferentially degraded, however, 4-CP exerted more inhibitory effect on 4-NP biodegradation. This study demonstrated the potential of A. chlorophenolicus A6 for biodegradation of 4-BP in mixed pollutants system by a flow through UPBR system.