正渗透处理高盐废水时电场抑制结垢的研究

针对高盐废水处理过程中正渗透(forward osmosis, FO)膜的结垢问题,文章分析外加电场对抑制FO膜石膏结垢的可行性;通过COMSOL Multiphysics研究不同电压下( $ \pm3,\pm5,\pm10 $ V)的电场变化规律,探究电场变化规律对抑制结垢的影响,进一步研究电场抑制结垢的作用机制。结果表明:无电场情况下,在10 h的运行时间内,FO膜水通量下降21.6%,膜的结垢指数为12.3%;当施加+3、-3 V电压时,FO膜水通量分别仅下降11.1%、12.1%,膜的结垢指数分别为0.6%、1.7%,且膜面结垢物质明显减少;当施加电压为正电压、电场方向为正时,抑制作用将随电压增大而增大,且施加正电压时对FO膜石膏结垢的抑制效果最佳,归因于介电泳(dielectrophoresis, DEP)力和电泳(electrophoresis, EP)力的协同作用,但是由于DEP力对石膏粒子有较强的抑制作用,不同电压下的外加电场对FO膜石膏结垢均有抑制作用。

Aiming at the problem of scale formation of forward osmosis(FO) membrane in the process of high-salt wastewater treatment, the feasibility of applying electric field to inhibit gypsum scale formation on FO membrane was analyzed. COMSOL Multiphysics was used to study the electric field changes under different voltages( $ \pm3 $ V, $ \pm5 $ V, and $ \pm10 $ V), explore the influence of electric field changes on the inhibition of scale formation, and further study the mechanism of the inhibition of scale formation by electric field. The results show that the flux of FO membrane decreases by 21.6% and the scaling index of the membrane is 12.3% over ten hours of operation without electric field. When +3 V and -3 V voltages are applied, the flux of FO membrane decreases by 11.1% and 12.1%, the scaling index of the membrane is 0.6% and 1.7%, respectively, and the scaling substance on the surface of the membrane is significantly reduced. When the applied voltage is positive and the direction of the electric field is positive, the inhibition effect increases with the increase of the voltage, and the inhibition effect of the positive voltage on FO membrane gypsum scaling is the best, which can be attributed to the synergistic effect of dielectrophoresis(DEP) forces and electrophoresis(EP) forces. However, due to the strong inhibition effect of DEP forces on gypsum particles, the applied electric field under different conditions can always inhibit the gypsum scale formation on FO membrane.