浸没式超滤海水预处理工艺

目前渤海湾反渗透海水淡化工程多采用新型的超滤膜法预处理工艺,为提高预处理效果,主要进行超滤膜材料和性能改进以及膜组件运行参数的优化,而对超滤膜前预处理的研究相对较少。本实验研究了超滤与混凝/超滤作为反渗透海水淡化预处理工艺的处理效果。考察了两种预处理工艺条件下浸没式超滤膜比通量(SF)、进水水质、产水水质,膜孔孔径变化、反洗效果及膜表面污染情况。结果表明,超滤与混凝/超滤两种预处理工艺都能达到产水SDI₁₅<2.0;混凝处理可以大幅度降低海水中颗粒数目,降低颗粒物在膜表面沉积和吸附的概率,减轻超滤膜的污染。当采用混凝/超滤工艺时超滤膜表面滤饼层疏松多孔,膜孔孔径变化较小,超滤膜比通量的衰减速度减缓,反洗时超滤膜比通量恢复率较高。

Seawater pretreatment with submerged ultrafiltration

The ultrafiltration(UF) pretreatment process is widely employed in reverse osmosis desalination project at Bohai gulf. Most researches focus on the improvements of UF membrane material, performances and the operation optimization of membrane module. But the pretreatment of UF is not widely studied. This experiment studied the effects of pretreatment to seawater by direct ultrafiltration process and coagulation/UF process. The submerged UF membrane specific flow(SF), water quality, membrane pore size distribution, the recovery rate of membrane SF, and the pollution of membrane surface were investigated for these two technologies. The results showed that both processes could achieve less than 2.0 SDI₁₅;the coagulation/UF process could significantly decrease the number of granules in seawater, thus reducing the probability of pollutants deposition and adsorption in membrane surface and improving the fouling extent of UF membrane. When the coagulation/UF process was adopted, the cake layer of membrane surface was more porous, the variation of membrane pore size distribution was insignificant, the attenuation of UF membrane SF was slowed, and the recovery rate of UF membrane SF was enhanced.