In this study, a pilot-scale FO membrane system was investigated for the pre-concentration of municipal wastewater using artificial seawater as the draw solution, followed by anaerobic methane fermentation of the concentrated wastewater. The FO system was operated for long-term wastewater concentration, and membrane performance was evaluated in terms of water flux, concentration behavior, and solute transport. The results demonstrated that municipal wastewater could be concentrated by approximately ten times while maintaining stable membrane performance during 70-day operation. Although membrane fouling occurred during operation, osmotic backwashing effectively restored 96% membrane flux, indicating that a large fraction of the fouling layer was reversible. During the FO concentration process, selective transport of dissolved components such as ammonium and sulfate was observed across the membrane, which did not influence microbial activity during downstream methane fermentation, approximately 50% conversion efficiency was achieved within 24 h. Energy analysis indicated that the integration of FO-based pre-concentration with anaerobic methane fermentation could potentially reduce the overall energy demand of wastewater treatment by approximately 40% compared with conventional AS treatment systems. These findings demonstrate the feasibility of FO-based wastewater concentration at pilot scale and highlight the potential of hybrid FO-anaerobic treatment systems for energy-efficient municipal wastewater treatment and resource recovery. • FO membranes concentrated municipal wastewater up to tenfold stably. • Continuous 70-day pilot run maintained stable flux with minimal fouling. • FO-concentrated sewage showed 50% methane conversion within 24 h.
Sun et al. (Fri,) studied this question.