In situ Groundwater Remediation Using Enricher Reactor – Permeable Reactive Biobarrier

A combined enricher reactor (ER) - permeable reactive biobarrier (PRBB) system was developed in this study to treat groundwater with periodically absent contaminants. ER is an offline reactor used to enrich bacteria by supplying necessary growth materials. Bench scale experiments on PRBBs with and without bacterial supply from the ER were conducted to evaluate PRBB removal performances for benzene absence periods of 10 and 20 days. The removal performance of the system was also investigated for the presence of ethanol during the benzene absence periods. The bioaugmentation from ER maintained the performance of PRBBs while PRBBs without the bioaugmentation experienced performance losses up to 30%. The presence of ethanol during the benzene absence periods also caused performance losses up to 30%. Molecular technique results showed that the longer benzene absence period caused greater changes in the bacterial community structure. The presence of ethanol during both of the benzene absence periods also caused changes in the bacterial community.