Influence of biofilm carriers on membrane fouling propensity in moving biofilm membrane bioreactor

► Sponge carriers in MB-MBR resulted in prolong filtration as compared to C-MBR. ► Higher fouling resistances in C-MBR responsible for higher membrane fouling rates. ► Excessive filamentous bacteria in C-MBR responsible for low permeability. ► Higher soluble EPS excretion major contributing factor to higher fouling in C-MBR. In moving biofilm membrane bioreactor (MB-MBR) sponge carriers for biofilm growth were coupled with conventional submerged membrane bioreactor (C-MBR). This study compared the fouling propensity of C-MBR with MB-MBR and investigated factors affecting fouling variations in both the systems. Membrane fouling tendencies were monitored in terms of trans-membrane pressure (TMP) and the fouling characterization included membrane fouling resistances in situ and specific cake resistance (SCR) in batch filtration cell. Comparison of TMP profiles depicted prolong filtration periods in MB-MBR. Cake layer resistance (Rc), pore blocking resistance (Rp) as well as SCR were higher in C-MBR. The study reveals that hybrid biomass in MB-MBR creates relatively more porous cake structure in the absence of filamentous bacteria which were found in abundance in C-MBR. Filamentous bacteria were also responsible for the release of high concentration of carbohydrates in the form of soluble extra polymeric substance (EPS) contributing to higher Rp in C-MBR.