Integration of an anaerobic fluidized-bed membrane bioreactor (MBR) with zeolite adsorption and reverse osmosis (RO) for municipal wastewater reclamation: Comparison with an anoxic-aerobic MBR coupled with RO.

This study compared the performance of an anaerobic fluidized bed membrane bioreactor (AFMBR)-zeolite adsorption-reverse osmosis (RO) system and an anoxic-aerobic MBR-RO system for municipal wastewater reclamation. Both MBR-RO systems were operated in parallel with the same operating conditions. The results showed that the MBR systems achieved excellent organic removals (>95%) and the anoxic-aerobic MBR could also remove ∼57% of soluble total nitrogen. Compared to the aerobic MBR, the AFMBR displayed better membrane performance with less energy consumption, attributed to effective membrane scouring by liquid-fluidized GAC particles. Furthermore, a zeolite column was employed to remove ammonia in the AFMBR permeate, which ensured comparable organic and nitrogen levels in the feeds to RO units in the two processes. Although less organic substances and microbial cells were accumulated on the RO membrane fed with AFMBR-zeolite column effluent, its fouling rate (∼6.5 ± 2.2 bar/day) was significantly greater than that fed with anoxic-aerobic MBR permeate (∼1.1 ± 1.5 bar/day). This may be associated with more severe inorganic colloidal fouling on the RO membrane, illustrated by an electrical impedance spectroscopy fouling monitoring system.