Monosodium glutamate as a draw solute for sewage thickening by forward osmosis–nanofiltration

Monosodium glutamate (MSG) was evaluated as a draw solute (DS) of forward osmosis–nanofiltration (FO-NF) process for sewage thickening. Water flux (Jw) and reverse draw solute flux (Js) through FO membrane with MSG were compared to those with NaCl as the reference DS. In addition, the influence of MSG to anaerobic digestion of concentrated sewage for methane gas production was investigated. The Js/Jw for MSG was 0.0015mol/L at 1M of initial concentration with a CTA(HTI) membrane, which was 6 % of that for NaCl, while the water flux (Jw) for MSG (ca. 10 L/m2h) was comparable to that for NaCl in FO processes. MSG recovered up to 98% by NF process, which changed with applied membrane and MSG concentration. The collected primary effluent from the full-scale wastewater treatment plant was thickened up to nine times in terms of volumetric concentration factor. The physical membrane flushing by a water could effectively recover the flux. The inhibitory effects of MSG on anaerobic methane production could be negligible and the gas production potential increased.