Nanofiltration fouling propensity caused by wastewater effluent organic matters and surface-water dissolved organic matters

Rejection of dissolved organic matters (DOMs) from wastewater treatment plant effluent (EfOM) and surface reservoir water (RW-DOM) by nanofiltration (NF) was comparatively studied to evaluate their influence on membrane fouling and to unveil the major causations. EfOM and RW-DOM were fractionated to determine the major components that preferentially form fouling layer and initiate biofouling. The results indicated that EfOM induced a rapid membrane permeability loss and a more complicated biofilm diversity than RW-DOM did. Hydrophilic components with small molecular weight (<3 kDa), and SMP in EfOM made a crucial contribution to membrane flux decline, while the hydrophobic large-molecular-weight components (>50 kDa) resulted in initially quick membrane fouling. The complex biofouling resulted from EfOM closely related with significant retention of SMP on the non-porous NF membrane surface, where the Proteobacteria phylum dominated the biofouling formed by microbial community growth and accumulation that gave rise to serious irreversible membrane fouling.