Forward osmosis for the concentration and reuse of process saline wastewater

Salt-contaminated soil generated by industrial activities has become a problem of concern over the last decades. While existing treatment technologies for these soils are efficient, the wastewater produced remains the major drawback. In this study, a novel application of forward osmosis (FO) was tested. The FO process operated in osmotic dilution mode was investigated in order to concentrate saline soil treatment wastewater and produce valuable process water. FO was chosen for this application since it is a low-energy technology and process adapted for complex liquid streams. Results from this study indicate that FO operated in osmotic dilution mode with a 1 M CaCl2 draw solution is able to recover 50% of the initial wastewater volume with an initial total dissolved solids concentration of 16.3 g/L. Following treatment, the draw solution can be reused as a cationic exchange solution with CaCl2 concentrations between 0.41 M and 0.44 M. No important solute transport from the feed to the draw solution was observed, except for some potassium drawn by the draw solution. This study demonstrated the potential of integrating the FO technology in the soil treatment industry in order to enhance water reuse in water-intensive processes