Impact of membrane bioreactor operating conditions on fouling behavior of reverse osmosis membranes in MBR-RO processes

► High F/M-MBR permeate led to higher RO fouling rate. ► Soluble polysaccharides and TEP on the RO membranes were associated with RO fouling. ► Propagation of bacterial cells on the RO membranes did not determine RO fouling. ► The presence of inline filters in the RO systems alleviated RO fouling. ► FA-like and microbial by-product-like substances were predominant in RO foulants.