Ultrafiltration performance of EfOM and NOM under different MWCO membranes: Comparison with fluorescence spectroscopy and gel filtration chromatography

Ultrafiltration performance of wastewater effluent organic matter (EfOM) and background natural organic matter (NOM) under different molecular weight cutoff (MWCO) membranes was investigated. Permeates of EfOM and NOM from ultrafiltration were systematically compared by using fluorescence spectroscopy and gel filtration chromatography. The results revealed that anthropogenic polysaccharide- and protein-like substances including polysaccharides, proteins, and colloids in EfOM were mainly removed by ultrafiltration with the 100 kDa membrane, which accounts for a large proportion of the total DOC in EfOM. With the decreasing of the membrane's MWCO, the humic substances in NOM were more easily removed compared with that in EfOM. The polysaccharides associated with the colloidal fraction, as well as the humic substances were speculated as the main potential foulants for UF membranes processing wastewater EfOM. As for NOM, humic substances were regarded as the main potential foulants. The fouling mechanism (cake filtrations or pore blocking) of EfOM or NOM in the ultrafiltration process was related with the MWCO of the membrane and the molecular size of the main foulants.