Eco-friendly regeneration of end-of-life PVDF membrane with triethyl phosphate: Efficiency and mechanism

Membrane will inevitably reach the end of its lifespan due to the irrecoverable fouling accumulation in membrane bioreactors (MBRs) during long-term operation. Herein, we developed an eco-friendly membrane regeneration strategy with triethyl phosphate (TEP), which successfully prolonged the lifespan of end-of-life (EOL) polyvinylidene fluoride (PVDF) membranes in a large-scale MBR. The regenerated (Rg) membrane exhibited a water permeance of 534.8 ± 45.7 L m−2 h−1 bar−1, along with stable rejection rate, which was comparable with that of the new membrane. Furthermore, compared to the membrane subjected solely to preliminary cleaning, the Rg membrane presented a more hydrophilic surface due to the combination of preliminary cleaning and solvent-based processing. Besides, the Rg membrane presented less fouling propensity with the critical flux of 15.2 L m−2 h−1, significantly higher than that of the EOL membrane (4.0 L m−2 h−1). Importantly, the membrane regeneration strategy was capable of guaranteeing the effluent quality in MBR systems for treating real municipal wastewater. This study provides an eco-friendly membrane regeneration strategy for effectively removing the irrecoverable foulants, thereby promoting the advancement of sustainable membrane-based wastewater treatment technology.