复合正渗透膜的过滤特性及对二级出水截留效果研究

The Filtration Properties and Rejection of Thin-Film Composite Forward Osmosis Membrane by Secondary Effluent

以某污水厂二级出水为原料液,采用型号TFC-ES正渗透膜研究过滤过程中的工艺特性(膜朝向、汲取液的种类及含量、错流速度)及适宜的膜清洗条件,以优化操作条件、降低浓差极化、减轻膜污染、提高正渗透膜性能。结果表明,以FO模式(活性层朝向原料液侧,AL-FS)、7.25 cm/s的错流速度、1 mol/L的Mg Cl2溶液作为汲取液时,复合正渗透膜的纯水通量大于9 L/(m2·h),反向盐截留率保持在99.90%以上。二级出水产生的可逆膜污染可采用简单的水力清洗方法,以17.4 cm/s的错流速度,去离子水清洗30 min后,膜通量恢复率大于90%。同时复合正渗透膜对二级出水中的溶解性固体(TDS)截留率高达98%以上,对金属离子Al^(3+)和Fe^(3+)的截留率可分别达到97%和100%,有机物、TN和TP的截留率均在82%以上,可为正渗透技术应用于废水处理提供相应参考。

In order to optimize the FO operating conditions, reduce membrane fouling and improve its performance, several properties （membrane orientation; different type and concentrations of draw solutions; crossflow rate） and suitable membrane cleaning conditions in FO filtration process were investigated by thin-film composite FO membrane when the secondary effluent of municipal sewage in Xi＇an was used as feed solution. The results showed that in FO mode （the active layer toward the feed solution, AL-FS）, 7.25 cm/s crossflow rate, 1mol/L MgCl2 as draw solution, the water flux was greater than 9 L/（m^2·h） by TFC-ES membrane, and the reverse salt rejection remained at 99.90%. Reversible membrane fouling caused by the secondary effluent could be used for hydraulic cleaning, the flux recovery rate was more than 90% after washing 30 min with DI water at 17.4 cm/s crossflow rate. In addition, the d!ssolved solids （TDS） of the secondary effluent removed more than 98% by TFC-ES membrane; the rejection rate of Al^3＋ and Fe^3＋ could reach to 97% and 100%, respectively; the rejection rate of organic matter, TN and TP were more than 82%. This study may provide a reference for the development of wastewater treatment processes.