Surface-manipulated membranes to accelerate biofilm formation and to resist bacterial detachment in MBfR for aerobic methane oxidation coupled to denitrification

Undesired long start-up time and unstable denitrification performance are major bottlenecks for engineering application of methane-based membrane biofilm reactors (MBfRs). In this study, two surface-manipulated membranes by respectively coating dopamine (DOPA) and grafting methoxy-poly(ethyleneglycol)-amine (mPEG-NH2) onto the base polypropylene (PP) membrane were prepared, and for the first employed to aerobic methane oxidation coupled to denitrification (AME-D) process in MBfRs for quick biofilm formation and improving denitrification performance. The experiments demonstrated that the modified membranes, especially for PP/DOPA/mPEGNH(2) membrane, accelerated biofilm formation, and then shorten above 31% start-up time compared to the base PP membrane. Meanwhile, the biofilm detachment resistances also improved in the MBfRs employing the modified membrane. Extended Deraguin-Landau-Verwery-Oxerbeek (XDLVO) theory analysis indicated these benefits mainly attribute to enhanced interfacial interaction energy, which is significant to microbial initial attachment onto membrane surface. 16S rRNA gene analysis demonstrated the modified membrane also preferentially increased the abundances of key microorganisms at initial stage. These findings revealed the importance of quick biofilm formation and robust detachment resistance by involving surface-manipulated membranes onto maintaining MBfRs efficiency and stability.