海水直流冷却电厂烟气脱硫废水处理工艺的研究

Study on Desulfurization Wastewater Treatment for the Power Plant with Seawater Cooling System

某海水直流冷却电厂除脱硫废水外,所有生产废水均已处理回用。为达到废水零排放目的,拟采用软化预处理–微滤–反渗透–电渗析工艺对脱硫废水进行膜法减量浓缩处理。对浓缩减量核心工艺进行了试验研究,结果表明反渗透装置在75%回收率下将微滤处理后的脱硫废水进行初步浓缩,反渗透系统运行压力、压差稳定,水中的Ca^(2+)、Mg^(2+)可被基本去除,单支膜脱盐率可达99%以上;采用电渗析将反渗透浓水进一步浓缩,可将反渗透浓水可溶解固形物质量分数由7%浓缩至21%;最终脱硫废水流量由20 m^3/h浓缩减量至2 m^3/h,大幅降低了后续结晶设备的成本及能耗。此工艺方案实施后,可提高水资源利用率,实现全厂废水零排放。

All industrial wastewater has been treated and reused at one coal-fired power plant with once-through cooling systemexcept the desulphurization wastewater. In order to achieve the goal of zero discharge of wastewater, the desulfurization wastewatertreatment is studied in this paper with the technique consisting of microfiltration （MF）, reverse osmosis （RO）, and electro-dialysis（ED） processes. The results show that at the RO recovery rate of 75%, the desalination rate is over 99% and the removal rates is over90% for Ca^2＋, Mg^2＋, SO4^2– and other divalent ions. After being concentrated by ED, the salt content increased from 7% to 21%.Ultimately, the effluent volume decreased from 20 m^3/h to 2 m^3/h, which could significantly reduce the cost of crystallizationequipment and energy consumption. After the implementation of this plan, the utilization factor of water resource could be improvedand the target of zero discharge of wastewater will be achieved.