超滤膜在处理农药废水过程中的膜污染行为分析
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摘要
由于高级氧化后的农药废水中含有大量小分子有机物,纳滤膜被应用于农药废水处理,但是,纳滤膜对进水水质有一定的要求,需要采用混凝-超滤法对高级氧化后的农药废水进行预处理.本文考察了混凝剂种类和用量对混凝效果的影响,并对3种孔径的聚偏氟乙烯(PVDF)中空纤维超滤膜在不同压力下的抗污染性能和临界操作条件进行了研究.结果表明,当聚合氯化铝(PAC)投放量为800mg/L,三氯化铁(FeCl_3·6H_2O)投放量为500mg/L,聚丙烯酰胺(PAM)投放量为10mg/L时,混凝-超滤组合工艺对废水中化学需氧量(COD_(Cr))、总磷(TP)、浊度、色度的去除率分别达到58.0%~59.1%、88.8%~89.7%、99.8%~99.9%、84%.平均孔径为20nm的PVDF超滤膜比平均孔径为11nm和40nm的PVDF超滤膜具有更高的临界通量和渗透性能.对膜污染、通量衰减模型的考察结果显示,孔内堵塞是导致孔径减小和通量衰减的主要原因.通过优化超滤膜孔径,能够显著降低膜孔堵塞现象,获得较高的运行通量.
Nanofiltration is used in pesticide wastewater treatment to remove the low-molecule organic matters following advanced oxidation.It is necessary to pretreat the wastewater before nanofiltration by coagulation-ultrafiltration(UF)process to meet the feed requirement of nanofiltration membrane system.The effects of coagulant type and dosage were investigated,and the anti-fouling performance and the critical operation condition of the three kinds of ultrafiltration membranes under different pressures were studied.The optimized concentrations of polyaluminium chloride(PAC),ferric chloride(FeCl_3·6H_2 O)and polyacrylamide(PAM)were 800 mg/L,500 mg/L,and 10 mg/L,respectively;under which conditions,the removal rates of COD_(Cr),total phosphorus,turbidity,chromaticity by the hybrid process were 58.0%~59.1%,88.8%~89.7%,99.8%~99.9%,84%,respectively.PVDF UF membrane with mean pore size of 20 nm exhibited higher critical flux and permeability compared with the membranes with pore size of 11 nm and 40 nm.Membrane fouling induced the reduction of membrane pore size,and a higher permeate flux can be obtained by optimizing the membrane pore size to reduce membrane fouling.
Nanofiltration is used in pesticide wastewater treatment to remove the low-molecule organic matters following advanced oxidation.It is necessary to pretreat the wastewater before nanofiltration by coagulation-ultrafiltration(UF)process to meet the feed requirement of nanofiltration membrane system.The effects of coagulant type and dosage were investigated,and the anti-fouling performance and the critical operation condition of the three kinds of ultrafiltration membranes under different pressures were studied.The optimized concentrations of polyaluminium chloride(PAC),ferric chloride(FeCl_3·6H_2 O)and polyacrylamide(PAM)were 800 mg/L,500 mg/L,and 10 mg/L,respectively;under which conditions,the removal rates of COD_(Cr),total phosphorus,turbidity,chromaticity by the hybrid process were 58.0%~59.1%,88.8%~89.7%,99.8%~99.9%,84%,respectively.PVDF UF membrane with mean pore size of 20 nm exhibited higher critical flux and permeability compared with the membranes with pore size of 11 nm and 40 nm.Membrane fouling induced the reduction of membrane pore size,and a higher permeate flux can be obtained by optimizing the membrane pore size to reduce membrane fouling.
引文
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[11]Qu F,Liang H,Zhou J,et al.Ultrafiltration membrane fouling caused by extracellular organic matter(EOM)from Microcystisaeruginosa:Effects of membrane pore size and surface hydrophobicity[J].J Membr Sci,2014,449:58-66.
[12]刘忠洲,张国俊,纪树兰.研究浓差极化和膜污染过程的方法与策略[J].膜科学与技术,2006,26(5):1-15.
[13]Takaara T,Sano D,Konno H,et al.Cellular proteins of Microcystisaeruginosa inhibiting coagulation with polyaluminum chloride[J].Water Res,2007,41(8):1653-1658.
[2]李荣喜,杨春平.有机磷农药废水处理技术进展[J].环境科学与管理,2008,33(9):84-87.
[3]方莎,贾海涛,吴念鹏.超滤联合高级氧化工艺深度处理工业园区污水[J].膜科学与技术,2016,36(1):99-103.
[4]Zhang Y,Pagilla K.Treatment of malathion pesticide wastewater with nanofiltration and photo-Fenton oxida-tion[J].Desalination,2010,263(1/3):36-44.
[5]杨青,张林生,李月中.纳滤膜在治理农药废水污染中的应用研究[J].工业水处理,2009,29(3):29-32.
[6]Field R W,Wu D,Howell J A,et al.Critical flux concept for microfiltration fouling[J].J Membr Sci,1995,100(3):259-272.
[7]姚金苗,王湛,梁艳莉,等.超、微滤过程中临界通量的研究进展[J].膜科学与技术,2008,28(2):69-72.
[8]张凯歌,李翠梅,查巧珍.太湖原水采用PVDF中空纤维超滤过程中临界通量与可持续通量的试验研究[J].膜科学与技术,2016,36(3):109-114.
[9]Neal P R,Li H,Fane A G,et al.The effect of filament orientation on critical flux and particle deposition in spacer-filled channels[J].J Membr Sci,2003,214(2):165-178.
[10]刘冲,吕晓龙,武春瑞等.关于超滤膜临界运行通量的探讨[J].膜科学与技术,2017,37(1):23-26.
[11]Qu F,Liang H,Zhou J,et al.Ultrafiltration membrane fouling caused by extracellular organic matter(EOM)from Microcystisaeruginosa:Effects of membrane pore size and surface hydrophobicity[J].J Membr Sci,2014,449:58-66.
[12]刘忠洲,张国俊,纪树兰.研究浓差极化和膜污染过程的方法与策略[J].膜科学与技术,2006,26(5):1-15.
[13]Takaara T,Sano D,Konno H,et al.Cellular proteins of Microcystisaeruginosa inhibiting coagulation with polyaluminum chloride[J].Water Res,2007,41(8):1653-1658.