不同材质及不同截留分子量超滤膜对二级出水中污染物的去除研究

Study on Removal Mechanism of Pollutants in Two Stage Effluent with Different Materials and Different Molecular Weight Ultrafiltration Membranes

为探究不同超滤膜对城市二级出水的处理性能,研究了不同材质(PES、PVDF)及不同截留分子量(50 k,100 k)4种超滤膜对二级出水中抗生素抗性基因和溶解性有机污染物去除及其对膜比通量的影响。结果表明,不同特性超滤膜直接过滤城市二级出水,能在一定程度上对污染物进行去除。对于抗性基因的去除,相同截留分子量的PES超滤膜处理效果明显优于PVDF超滤膜,而相同材质的超滤膜50 k的处理效果比100 k的处理效果好。对可溶性有机物的去除,50 k的超滤膜比100 k的去除效率高10.0%(PES),13.6%(PVDF),50 k的两种材质超滤膜无明显差异性。二级出水经超滤后,50 k的超滤膜可以有效去除腐殖酸类物质,而100 k无法去除,说明原水中腐殖酸类物质大小在50~100 k范围内。相同材质超滤膜,随着截留分子量减小,膜的固有阻力增大,膜通量下降迅速,反冲洗后其膜比通量恢复程度较大,可逆膜污染占比较高;相同截留分子量的超滤膜,PVDF比PES的膜比通量损失快,反冲洗后膜比通量恢复程度较小,不可逆膜污染严重。在实际应用中,应根据不同水质特点及要求选择合适的材质和截留分子量。

In order to study the treatment performance of different ultrafiltration membranes on municipal secondary water,the effects of four ultrafiltration membranes(PES,PVDF)and different molecular weight(50 k,100 k)on the removal of antibiotic resistance genes and soluble organic pollutants in secondary effluent and their effects on membrane specific fluxes were studied.The results show that ultrafiltration membrane with different characteristics can directly filter the secondary effluent of the city and remove the pollutants to some extent.For the removal of resistant genes,the treatment effect of pes ultrafiltration membrane with the same molecular weight is better than that of PVDF ultrafiltration membrane,while the treatment effect of 50 k ultrafiltration membrane with the same material is better than that of 100 k.The removal efficiency of 50 k ultrafiltration membrane is 10.0%(PES),13.6%(PVDF)and 50 k ultrafiltration membrane has no significant difference.After ultrafiltration of secondary effluent,50 k ultrafiltration membrane can effectively remove humic acid substances,but 100 k can not remove those,indicating that the size of humic acid substances in raw water is in the range of 50~100 k.For the ultrafiltration membrane with the same material,the intrinsic resistance of the membrane decreases with the decrease of the molecular weight of the interception,the flux of the membrane decreases rapidly,the recovery degree of the membrane specific flux aft backwashing is larger,and the pollution of the reversible membrane is higher.The PVDF membrane with the same entrapment molecular weight is faster than PES membrane specific flux loss,the recovery degree of the membrane specific flux after backwashing is small,and the irreversible membrane pollution is serious.In practical application,appropriate materials and molecular weight should be selected according to different water quality characteristics and requirements.