天然有机物对国产纳滤膜的污染及清洗效果研究

Study on the Fouling and Cleaning Effect of Natural Organic Matter on Domestic Nanofiltration Membrane

为考察水体中天然有机物(NOM)对纳滤膜性能产生的影响,以腐殖酸(HA)、牛血清蛋白(BSA)和海藻酸钠(SA)分别模拟水中常见NOM,腐殖质、蛋白质和多糖,对国产NF-1812纳滤膜进行单组分及其混合物定性定量有机污染及清洗实验。结果表明,有机污染造成膜通量下降,膜污染程度为SA>HA>BSA;NOM截留率可稳定在99.2%~99.6%;膜污染阻力主要为浓差极化阻力,其次是凝胶层阻力和内部污染阻力,有机污染液综合黏度和综合含量越大,浓差极化阻力的比例越高;对多组分有机污染膜进行错流速度9 cm/s的物理水力清洗和pH=10.0的质量分数分别为0.1%的NaOH+0.025%Na-SDS化学药剂清洗,膜通量、NOM截留率、苦咸水截留率、SEM成像均恢复至原膜状态,纳滤膜清洗效果良好,适用于中国西北苦咸水地区。

In order to investigate the effect of natural organic matter(NOM)on the performance of nanofiltration(NF)membrane in water,the humic acid(HA),bovine serum albumin(BSA)and sodium alginate(SA)were used to simulate common NOM:humic substances,proteins and polysaccharides in water.Qualitative and quantitative organic fouling and cleaning experiments of single component and multi-components were carried out on the domestic NF-1812 NF membrane.The results showed that the membrane flux decreased due to organic fouling.The NOM fouling degree of NF membrane was SA>HA>BSA,and the NOM rejection rate was stable at 99.2%~99.6%.The main fouling resistance of NF membrane was concentration polarization resistance,followed by gel layer resistance and internal fouling resistance.Moreover,the greater the comprehensive viscosity and comprehensive content of organic contaminated solution,the higher the concentration polarization resistance.The cross-flow velocity of 9 cm/s and the chemical cleaning of mass fraction of 0.1%Na OH+0.025%Na-SDS with pH 10.0 were carried out on the multi-component organic fouled membranes,the membrane flux,NOM rejection rate,brackish water rejection rate and scanning electron microscopy(SEM)images were restored to the original membrane state.The results indicated that the domestic NF membrane has a good cleaning effect and is suitable for the application in the brackish water area of northwest China.