Removal of petroleum pollutants and monitoring of bacterial community structure in a membrane bioreactor

The long-term operational stability (159 d) in removal of organics and ammonia from synthetic wastewater was investigated. The experiment was carried out in two identical plug flow membrane bioreactors (MBR) (each with a submerged A4 Kubota membrane) operated under aerobic conditions. The vacuum distillate of a crude oil fraction in the emulsified state, which was used to model the petroleum pollutants, was added into the feed medium. The performance of biological treatment was evaluated by physicochemical analyses such as nitrogen forms, COD, and BOD. Additionally, monitoring of PAHs in the wastewaters was performed using HPLC-diode array detector. Moreover, the community structure of bacteria was analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis. The MBR treatment was very effective with reduction by more than 90% of COD and Total Organic Carbon. Nearly complete removal of petroleum originated non-polar micropollutants was observed. The influence of the highest dosage of petroleum pollutants (1000 μL L−1) on the bacterial community was noted.

Research highlights
► Determination of effect of petroleum substances on bacterial community structure in MBR.
► Effect of petroleum contamination on treatment performance (COD, TOC removal and nitrification) in MBR.
► Adjustment of SPE procedure and HPLC conditions (gradient, solvents) for determination of PAHs.
► Monitoring of persistent micropollutants removal (PAHs) in MBR system.