Feasibility of the highly-permselective forward osmosis membrane process for the post-treatment of the anaerobic fluidized bed bioreactor effluent

Abstract

A laboratory-made high-performance thin-film composite (TFC) forward osmosis (FO) membrane supported by a polyacrylonitrile (PAN) support was firstly employed to treat the effluent produced by an anaerobic fluidized bed bioreactor (AFBR). Synthetic wastewater was prepared to operate the AFBR, which produced the effluent for the FO process as post-treatment. The performance of the FO membrane was characterized via the measurement of the permeate flux, reverse salt (NaCl) flux and the rejection efficiency of ammonium nitrogen (NH4-N) mostly present in the AFBR effluent having low removal characteristics. An ultrathin and highly-crosslinked polyamide selective layer combined with the PAN support having a low structural parameter of the prepared PAN-supported TFC (PAN-TFC) membrane resulted in higher rejection to both nitrogen and salt compared to a commercial FO membrane. Importantly, the rejection of NH4-N higher than 70% was achieved by the PAN-TFC FO membrane. At 0.5 M NaCl draw solution, the PAN-TFC membrane exhibited the nitrogen flux of 0.92 ± 0.01 g m−2 h−1 and the permeate flux of 25 L m−2 h−1. The results demonstrate that the FO membrane can be one of the promising ways to effectively control the removal of contaminants present in AFBR effluent such as NH4-N as a post-treatment.