Improved phenol degradation in high-phenol-fed MBR by membrane-driven containment of non-settling biodegradation microbes

Phenol is one of major pollutants in industrial wastewater with high remediation priority. In this study, the role of membrane in phenol degradation in high-phenol-fed MBR (membrane bioreactor) was explored. Phenol elimination in high-phenol-fed MBRs resulted in complete mineralization and the high-phenol-fed MBR exhibited greater biomass-specific phenol removal rates (0.4-1.5 mg phenol/(mgVSS·d) than the low-phenol-fed MBR. In the high-phenol-fed MBR, filamentous non-settling microbes were more abundant than in the low-phenol-fed MBR. In the following batch experiment, high-acclimated and non-settling microbes were separately collected from the high-phenol-acclimated bioreactor, and their specific phenol degradation was determined at 5.1 mg phenol/(mgVSS·d). The greater specific phenol degradation rate of the non-settling microbes than the observed phenol elimination rate in the high-phenol-fed MBR indicates that the high-phenol-acclimated and non-settling microbes had greater degradation activity than the rest of sludge microbes in the bioreactor. According to these findings, the role of membrane in the high-phenol-fed MBR was identified as the containment of non-settling and biodegradative microbes in bioreactor, and in turn, the membrane-driven increase of non-settling phenol degrading microbes enhanced phenol elimination in the high-phenol-fed MBR.