Understanding ultrafiltration membrane fouling by soluble microbial product and effluent organic matter using fluorescence excitation-emission matrix coupled with parallel factor analysis

Membrane fouling of soluble microbial product (SMP) and effluent organic matter (EfOM) in ultrafiltration (UF) was investigated by using fluorescence excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC) as well as dissolved organic carbon (DOC) and polysaccharides measurement. SMP and EfOM samples were generated in bench-scale sequencing batch reactors (SBRs) fed with synthetic wastewater and domestic wastewater under different solid retention times (SRTs). Results showed that EfOM contained more DOC and more sub-fractional components except for tyrosine-like substances compared to SMP, however, SMP caused more severe fouling. The fluorescence intensity of tyrosine-like substances in UF feed showed good correlation with membrane fouling index, suggesting that it can serve as a fouling potential indicator. The mass balance analysis also indicated that the tyrosine-like substances was a major foulant. Membrane fouling was alleviated as SRT increased, which can be associated with the decrease of protein-like (tyrosine-like and tryptophan-like) substances under longer SRT.