Effect of mechanical scouring on fouling control in greywater filtration with fluidized bed submerged membrane reactor for decentralized wastewater treatment process

Synthetic greywater was applied into a novel, fluidized submerged membrane reactor (FSMR) to compare membrane fouling with three different types of scouring agents: granular activated carbon (GAC), tubular polyvinylidene fluoride (PVDF) media, and spherical polyethylene terephthalate (PET) beads. Trans-membrane pressure (TMP) was investigated to estimate the extent to the fouling in the FSMR operated at 13 and 40 L/ m2.h of permeate flux. The selection of scouring agents affected transient behavior of TMP value significantly to reduce membrane fouling. Fluidization of spherical PET beads driven by recirculating bulk suspension only through the FSMR was a prominent way to mitigate fouling. However, the cake layer was formed on membrane surface extensively as GAC or tubular PVDF media was fluidized over the course of reactor operation. At 13 L/ m2.h, the TMP reached 0.74, 0.7, and 0.04 bar after 7 d operation with FSMR added with GAC particles, tubular PVDF media, and spherical PET beads as scouring agent, respectively. For the non-adsorbing PET beads, organic compound such as humic acids and proteins were a main organic fraction in cake layer. The organic removal efficiency was enhanced by complex formation resulting from the concentrated greywater in the reactor operated during extended filtration time. However, small carbon particles produced by the pulverization of GAC particles in the FSMR system disrupted fouling control and led rapid TMP rise.