Effect of different types of fillers in membrane bioreactors for greywater treatment and membrane fouling

This study investigated the effects of different types of fillers fed into membrane bioreactors (MBR) in greywater treatment for water purification effect, membrane fouling and microbial community structure. Two MBR systems of hollow fiber membrane and flat sheet organic membrane were running with floating sponge filler and fixing combination filler. The MBR systems with filler improved the removal rate of ammonia nitrogen, total nitrogen, and total phosphorus compared with that without filler, especially the effect of floating sponge filler was obvious (91.49%, 71.53%, and 72.35% in the flat sheet membrane system). The floating sponge filler also effectively improved the permeation performance of the MBR system, but the fixed type filler (combination filler) accelerated membrane fouling and reduced the permeation performance of the system. This finding may be due to the higher abundance of Gammaproteobacteria (relative abundance 38.3%) and Bacteroidia (relative abundance 8.35%) on the filler surface. Feeding fillers into MBR can improve the nitrogen removal capacity, effluent quality, and permeability of the system. However, it depends on the type and material of different fillers.