Performance evaluation of boron removal from wastewater containing high boron content according to operating parameters by air gap membrane distillation

The removal performance of boron from real wastewater was conducted to determine the effect of different parameters on permeate water flux and boron removal efficiency by air gap membrane distillation (AGMD) system in this study. These parameters include boron concentration, membrane pore size, and membrane material. Before real wastewater tests, the experiments were conducted with saline water (%1 (w/v) NaCl) to stabilize the air gap membrane distillation system. Then, experiments were carried out in an air gap membrane distillation system using real wastewater. In the experiments, two different membrane materials (polytetrafluoroethylene (PTFE) and polypropylene (PP)) were used to examine the effect of membrane material. Also, experiments were conducted with membranes that have mean pore size of 0.20 and 0.45μm to examine the effect of membrane pore size on the permeate flux. To evaluate the effect of boron concentration, wastewaters at three different boron concentrations (2598, 2795 and 6242 mg/L B) were treated in the AGMD system. The results illustrate that removal of boron in all conditions was obtained above 99%. In conclusion, increasing boron concentration at feed wastewater, permeate water flux was decreased. When the mean pore size was increased from 0.20 to 0.45μm, permeate flux was enhanced. Furthermore, PP membranes had the maximum permeate flux in AGMD tests.