Rejection of antimony in dyeing and printing wastewater by forward osmosis

Wastewater containing heavy metal antimony (Sb) from textile and printing industry has high potential toxicity to environment and human health. In this study, forward osmosis (FO) technology was firstly used to remove Sb from both model Sb wastewater and real dyeing and printing wastewater. The evaluation of FO performance with different feed solution pH and NaCl concentration indicated that the water flux and reverse salt flux were proportional to both the feed solution pH and NaCl concentration. The rejection of Sb decreased with NaCl concentration while increased with feed solution pH. The addition of Cr (VI) as co-existing ions in the feed further increased Sb removal for a range of feed solution pH and NaCl concentration. FO process exhibited high removal efficiency for Sb (>99.7%) and other water quality parameters (TN, TP, NH₃-N, SS, COD and TOC) when it was applied for the treatment of real dyeing and printing wastewater. The mass balance of Sb in FO process was also analyzed to investigate the membrane fouling and rejection mechanism.