Fouling characteristic of reverse osmosis membrane for reclaimed water treatment operating under cold winter condition

Membrane fouling is currently a significant constraint on reverse osmosis (RO) processes, and little is known about the fouling characteristics in winter. In this paper, RO membranes operating in winter were autopsied to explore the foulant composition. Both organic and inorganic foulant contents showed a decreasing trend from the front-most model to the end-most model, and organics were the main foulant, accounting for 93.90 %–95.24 % of the RO membrane surface deposits. Al, Ca, Mg, Na and K were dominant inorganic scalants, and the deposition amount of Al on the membrane surface reached up to 18.45 mg/m2, although the concentration of Al in RO feed water was as low as only 38.21 μg/L. Organic fouling was more severe than biofouling. The predominant bacteria in water and on the membrane of different positions differed significantly. The relative abundance of Actinobacteriota, Actinobacteria, Mycobacteriaceae, and Mycobacterium on the front-most membrane at the phylum, class, family, and genus levels accounted for approximately 73 %. The percentage of Proteobacteria on the end-most membrane at the phylum level was 85.85 %. This study helps to elucidate the composition of membrane fouling under low temperatures in winter and provides a reference for pretreatment and chemical cleaning.