在超滤前进行混凝预处理可以减轻膜污染,混凝/超滤组合工艺已得到广泛的认可。在混凝/超滤工艺中引入曝气,形成了混凝/气提/超滤组合水处理新工艺。通过试验分析不同曝气量条件下的跨膜压差(TMP)、膜污染总阻力(Rt)以及膜污染指数(UMFI),探讨了不同曝气量下的膜污染情况。结果表明,混凝和曝气有利于减轻膜污染;并且随着曝气量的增加,TMP和Rt增长速率呈降低的趋势,UMFI值也逐渐减小。当曝气量从零增加到180 m L/min时,TMP和Rt的平均增长速率分别从0.211 k Pa/h和0.037×1012m^(-1)/h降低至0.065 k Pa/h和0.026×1012m^(-1)/h,UMFI值从0.001 18 m^2/L降低至0.000 30 m^2/L,膜污染程度显著降低。
To advance commercial application of forward osmosis （FO）, we investigated the effects of two additives on the performance of polysulfone （PSf） based FO membranes： one is poly（ethylene glycol） （PEG）, and another is PSf grafted with PEG methyl ether methacrylate （PSf-g-PEGMA）. PSf blended with PEG or PSf-g- PEGMA was used to form a substrate layer, and then polyamide was formed on a support layer by interfacial polymerization. In this study, NaC1 （1 mol·L^-1） and deionized water were used as the draw solution and the feed solution, respectively. With the increase of PEG content from 0 to 15 wt-%, FO water flux declined by 23.4% to 59.3% compared to a PSf TFC FO membrane. With the increase of PSf-g-PEGMA from 0 to 15 wt-%, the membrane flux showed almost no change at first and then declined by about 52.0% and 50.4%. The PSfwith 5 wt-% PSf-g-PEGMA FO membrane showed a higher pure water flux of 8.74 L·m^-2·h^-1 than the commercial HTI membranes （6-8 L·m^-2·h^-1） under the FO mode. Our study suggests that hydrophobic interface is very important for the formation ofpolyamide, and a small amount of PSf- g-PEGMA can maintain a good condition for the formation of polyamide and reduce internal concentration polarization.
