Elucidation of biofouling mechanisms on membranes in a semi-batch reverse osmosis process for surface water treatment

초록

With declining surface water quality and rising demand for water reuse, reverse osmosis (RO) has gained attention as a water treatment technology. Semi-batch reverse osmosis (SBRO) can achieve higher recovery than conventional RO, yet its application to surface water remains vulnerable to biofouling due to organic matter and microbial constituents in the feed. This study elucidates the biofouling mechanisms associated with SBRO during surface water treatment. Pretreatment evaluation indicated that soluble extracellular polymeric substances (EPS) remained largely unchanged, whereas adenosine triphosphate (ATP) decreased. Although pretreatment reduced ATP, water flux declined by 5.20% in RO and 38.69% in SBRO over three weeks, with more pronounced mixed fouling involving biofouling and silicate-related inorganic deposition observed in SBRO. During SBRO concentration, ATP increased without marked changes in soluble EPS, while microbial diversity and phylogenetic breadth decreased relative to RO. In parallel, Verrucomicrobiota became enriched under osmotic stress, and predicted functional profiles were dominated by biosynthesis and energy metabolism. These findings suggest that biofouling progression in SBRO was more closely associated with microbial metabolic activity than with EPS accumulation, and that ATP may serve as an early indicator of biofouling development. Accordingly, pretreatment strategies should target suppression of microbial energy activity in surface water, while biological or adsorptive polishing may further limit microbial energy production by reducing residual assimilable organic carbon.

키워드