纳滤膜过滤MBR出水的污染原因与清洗方法

环境科学ENVIRONMENTALSCIENCEVo1．29．No．9Sep．，2008纳滤膜过滤MBR出水的污染原因与清洗方法陈健华，黄霞(清华大学环境科学与工程系环境模拟与污染控制国家重点联合实验室，北京100084)摘要：为研究膜．生物反应器(MBR)出水对纳滤膜的污染原因及清洗方法，使用场发射扫描电镜、傅立叶变换红外光谱仪、原子力显微镜和接触角仪对经MBR出水污染的纳滤膜表面污染层进行了检测．结果表明，纳滤膜表面污染物包括有机物和无机物，所含元素包括磷、镁等．对经过不同清洗步骤的膜表面进行的检测表明，柠檬酸清洗可以去除镁和大部分磷，这些物质主要以无机形态存在于膜面污染物中；后续NaOH清洗可以进一步去除磷，这部分磷主要来自有机酸、有机磷或蛋白质等膜面污染物．污染使膜表面粗糙度由79．5nm增大至l11．2nm，但接触角由55．6。变为62．1。，表明亲水性变化不大；酸洗后表面粗糙度显著减小至51．9nm，接触角变为96．0。，表明有机污染物暴露出来，膜面呈现疏水性；再经碱洗后，膜面粗糙度与亲水性均接近于新膜．这些结果说明，先酸洗后碱洗的方法可以去除绝大部分的膜面污染物，进一步推知膜污染初期主要为有机污染，之后无机物的作用使污染进一步加重．关键词：纳滤膜；膜污染；清洗方法；表面分析；膜．生物反应器中图分类号：X703．1文献标识码：A文章编号：0250．3301(2008)09．2481．07FoulingReasonsandCleaningnethodsofNanofiltrationnembraneFiltratedwiththeEfluentofMembraneBioreactorCHENJian—hua，HUANGXia(ESPCStateKeyJointLaboratory，DepartmentofEnvironmentalScienceandEngineering，TsinghuaUniversity，Beijing100084，China)Abstract：Inordertoinvestigatethefoulingreasonsandcleaningmethodsofnanofihrationmembranefouledwiththeefluentofmembranebioreactor(MBR)，FEG—SEM—EDS，FrIR，AFMandcontactanglesystem，wereappliedtoanalyzethemembranefoulinglayer．Theresultsshowedthat，thefoulantsincludedbothorganicandinorganicsubstances，whichcontainedphosphorous(P)andmagnesium(Mg)．Afterinvestigationsofmembranesurfacesthroughdifferentcleaningsteps，itwasshowedthatcriticacidcleaningcouldremoveMgandmostofP，whichwereinorganic；andsubsequentsodiumhydroxidecleaningcouldremovetheresidualP，whichprobablycamefromorganicacid，organicphosphorousorprotein．Theroughnessincreasedfrom79．5nmto111．2nmwithfouling，butthehydrophilicitydidn’tchangeobviouslyaccordingtothecontactanglefrom55．6。to62．1。．Butafteracidcleaning，theroughhessdecreasedto51．9nmandthecontactanglechangedtobe96．0。，whichshowedtheorganicfoulantswereexposedandthesurfacechangedtobehydrophobic．Andaftersubsequentalkalicleaning，theroughnessandthehydrophilicitywerebothclosetothoseofthenewmembrane．Theseresultsconcludedthatacidcleaningfollowedbyalkalicleaningcouldremovemo6tofthefoulants．Itwasalsosuggestedthatorganicmattersfouledthemembraneintheinitial