Effect of imposed flux on fouling behavior in high rate membrane bioreactor

The influence of imposed flux and aeration rates on membrane fouling in a submerged membrane bioreactor was studied. The experiments were conducted at four imposed fluxes and three aeration rates. The effect of flux on the reduction of membrane fouling was much higher than that caused by aeration rate. A lower flux of 20 L/m2 h produced 75 times more water than a higher flux of 40 L/m2 h with an aeration rate of 2 L/min. Low flux showed slightly higher removal of NH4–N and 93–96% removal of dissolved organic matter and chemical oxygen demand. Imposed flux also had a significant effect on the composition of organics present in the soluble microbial product (SMP) and extracellular polymeric substances (EPS). At a higher flux, both SMP and EPS had organics of high molecular weight (MW) of around 48 kDa as well as lower MW organics below 200 Da.

► Effect of imposed flux and aeration rates on membrane fouling in MBR and SMP and EPS of mixed liquor.
► Linear relationship between aeration rate and imposed flux with membrane fouling.
► Relation between imposed flux and MWD of organics were studied.
► Imposed flux significantly affected the composition of organics in SMP and EPS.