Effects of scouring on membrane aerated biofilm reactor performance and microbial community composition

Abstract

This study investigated the effects of scouring on Membrane Aerated Biofilm Reactors (MABRs). Laboratory-scale MABRs were operated under conditions typical for municipal wastewater. Scouring was induced by bubbling dinitrogen gas through the reactor bulk at low and high frequencies (LF and HF). At low nitrogen surface loads, almost complete ammonium removal was observable while HF scouring resulted in less total nitrogen (TN) removal compared to LF scouring. High nitrogen surface loads combined with HF scouring resulted in a higher TN removal as LF scouring. HF scouring resulted in around four times more sludge production and less residual biofilm mass compared to LF scouring. 16S amplicon sequencing of the biofilm, detached biomass and flocs revealed major differences between the microbial community compositions of these fractions. These results indicate that by varying the scouring strategy is a potential control mechanism for MABR operation and can help to reach specific treatment targets.

Keywords: Biofilm control; Detachment; MABR; Microbial community composition; Nitrogen removal; Sludge production.