Forward osmosis-extraction hybrid process for resource recovery from dye wastewater

In this work, a novel combined forward osmosis (FO)-extraction process is applied for resource recovery and dye wastewater treatment simultaneously. FO process is utilized to concentrate the dye wastewater, to achieve a higher concentration factor and lower energy consumption compared with NF process. The FO pre-treatment can increase the dye concentration and reduce the stream volume, thereby reducing the reagent consumption in the subsequent extraction process and lowering the processing cost. In the extraction process, the compositions of the extractant and stripping agent are also optimized, and the recovery rates for congo red, fuchsin acid, orange acid and methyl blue are 97.8%, 82.1%, 80.1% and 76.1%, respectively. In addition, the FO process is driven by the simulated seawater (0.6 M NaCl) draw solution, which can avoid the energy-intensive operation for the draw solution regeneration. Therefore, this study provides a sustainable strategy for the dye wastewater treatment in the coastal areas.