混凝处理防止膜污染的作用与机理

董秉直,夏丽华,陈艳,等.混凝处理防止膜污染的作用与机理[J].环境科学学报,2005,25(4):530-534DONGBingzhi,XIALihua,CHENYan,etal.Theeffectandmechanismsofcoagulationonpreventingmembranefromfouling[J].ActaScientiaeCircumstantiae,2005,25(4):530-534混凝处理防止膜污染的作用与机理董秉直3,夏丽华,陈艳,高乃云,范瑾初同济大学环境科学与工程学院,上海200092摘要:通过膜过滤混凝上清液的方法,并比较膜进水和透过水中有机物相对分子质量分布的变化,探讨了混凝防止膜污染的作用和机理.结果表明,相对分子质量大于1000的有机物是造成膜污染的主要因素,而相对分子质量小于1000的有机物对膜污染的影响较小.尽管混凝能有效地去除相对分子质量较大的有机物,但混凝防止膜污染的效果与其投加量有密切的关系.较低的混凝投加量(25mg·L-1)防止膜污染的效果较差,较大的投加量(>50mg·L-1)防止膜污染的效果较好.UV254能更好地反映有机物对膜污染的影响程度,如何有效地去除这类有机物是防止膜污染的关键.混凝防止膜污染的效果与去除相对分子质量大于1000的UV254的程度密切相关.试验结果表明,混凝去除这类有机物的效果达到50%时,可有效地防止膜污染.关键词:超滤膜;混凝;滤饼层;膜污染;有机物分子量分布文章编号:025322468(2005)0420530205中图分类号:X70311文献标识码:ATheeffectandmechanismsofcoagulationonpreventingmembranefromfoulingDONGBing2zhi3,XIALi2hua,CHENYan,GAONai2yun,FANJin2chuSchoolofEnvironmentalScienceandEngineering,TongjiUniversity,Shanghai200092,ChinaAbstract:Bymeansoffiltrationofcoagulatedsupernatantandcomparisonofthedistributionoforganicmolecularweightforthefeedandpermeatedwater,themechanismsandtheeffectsofcoagulationaspretreatmentformembranewerestudied.Theexperimentalresultsshowedthatthekeyfactorresponsibleformembranefoulingwasorganicsofmolecularweight(MW)greaterthan1000,andtheeffectoforganicsMWsmallerthan1000onmembranefoulingwasminor.Althoughcoagu2lationcouldremovegreaterMWorganicseffectively,theeffectofcoagulationonpreventingmembranefromfoulingwascloselyrelatedtocoagulantdosages.Theef2fectofcoagulationtreatmentwithrelativelylowdosages(25mg·L-1)waspoor,andgoodeffectcouldbeachievedbyrelativelyhighdosages(>50mg·L-1).UV254wasagoodparameterforunderstandinginfluenceoforganicsonfouling,sohowtoremoveUV254organicseffectivelywascriticalforpreventingfouling.TheeffectofcoagulationonpreventingmembranefoulingiscloselyrelatedtotheamountsofUV254withMWgreaterthan1000removedbycoagulation.TheresultobtainedfromthisstudydemonstratedthatwhemUV254withMWgreaterthan1000wasremovedby50%bycoagulation,thefoulingcouldbepreventedeffectively.Keywords:ultrafiltrationmembrane