Attribution of photocatalysis of fluorescent natural organic matter fractions to the alleviation of ceramic membrane ultrafiltration fouling

•Photocatalysis of fluorescent NOM fractions to alleviate UF fouling was proposed.•NOM was oxidized by BRGT into small molecules and hydrophilic moieties.•Fluorescent humic (C1) and protein/polyphenol(C2) components were degraded by ·O2−.•Protein-like substances (C3) were highly effectively adsorbed and degraded by h+.•The transformation of domain fouling mechanism depended on photocatalysis time.