Integrated loose nanofiltration-electrodialysis process for sustainable resource extraction from high-salinity textile wastewater.

Effective extraction of useful resources from high-salinity textile wastewater is a critical pathway for sustainable wastewater management. In this study, an integrated loose nanofiltration-electrodialysis process was explored for simultaneous recovery of dyes, NaCl and pure water from high-salinity textile wastewater, thus closing the material loop and minimizing waste emission. Specifically, a loose nanofiltration membrane (molecular weight cutoff of ~800 Da) was proposed to fractionate the dye and NaCl in the high-salinity textile wastewater. Through a nanofiltration-diafiltration unit, including a pre-concentration stage and a constant-volume diafiltration stage, the dye could be recovered from the high-salinity textile wastewater, being enriched at a factor of ~9.0, i.e., from 2.01 to 17.9 g·L−1 with 98.4% purity. Assisted with the subsequent implementation of electrodialysis, the NaCl concentrate and pure water were effectively reclaimed from the salt-containing permeate coming from the loose nanofiltration-diafiltration. Simultaneously, the produced pure water was further recycled to the nanofiltration-diafiltration unit. This study shows the potential of the integration of loose nanofiltation-diafiltration with electrodialysis for sufficient resource extraction from high-salinity textile wastewater. [Display omitted] • Integration of loose nanofiltration (NF) with electrodialysis is proposed for textile wastewater treatment. • Loose NF-diafiltration enriches the dye from 2.01 to 17.9 g·L−1 with a purity of 98.4%. • 99.94% of salt is removed by loose NF-diafiltration with 7 diavolumes. • Subsequent electrodialysis effectively recovers water and salt from NF-diafiltration permeate. • No significant fouling of ion exchange membranes is observed in electrodialysis performance. [ABSTRACT FROM AUTHOR]