Enricher reactor--permeable reactive biobarrier approach for removing a mixture of contaminants with substrate...

A laboratory-scale enricher reactor (ER) - permeable reactive biobarrier (PRBB) system was studied to address performance loss of a PRBB due to substrate interactions among a mixture of benzene, toluene, ethylbenzene, and xylene (BTEX) in groundwater, when the mixture reappeared after a 10-day absence period. Toluene and BTEX as an inducer in ER were compared to investigate toluene as a potential single inducer in ER. PRBBs without ER augmentation experienced performance losses ranging from 11% to 35% for PRBBs initially inoculated with toluene degraders and 22% to 33% for PRBBs initially inoculated with BTEX degraders. Bacterial communities changed substantially in these PRBBs after the absence period, which could contribute to the performance losses. PRBBs augmented with toluene degraders overcame the inhibition interaction between benzene and toluene, and showed a superior removal performance for toluene degradation suggesting that toluene can be used as a single inducer in an ER.