水污染处理文献综述英文上课讲义.docx

水污染处理文献综述英文上课讲义.docx

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水污染处理文献综述英文上课讲义

水污染处理文献综述英文

Applicationofmulti-soil-layersystem（MSL）inruralwastewatertreatment

Abstract:

withthecontinuousimprovementoflivinginruralfarmers,thewaterconsumptionofresidentsisincreasing,ruralsewageemissionswillcontinuetoincrease,ifnottreateffectively,thewaterenvironmentinruralareaswillbeseriousdeteriorated,andinfluencethelifequalityofruralresidents.Inthiscasethispaperpresentsadecentralizedsewagetreatmentsystem,multi-soil-layersystemtechnology（MSL）applicationintheruralsewagetreatment,thispapersummarizesthenewtechnology,youcanbetterunderstandandpractice,especiallyinthedevelopingcountrieswhereisinneedofthistechnology.Intheforeseeablefuture,itcanprotectpublichealthandthesustainabledevelopmentoftheenvironment,anditalsoprovidesanewwayforruralsewagetreatment.

Keywords:

ruralsewage;multi-soil-layeringsystem;distributed

1.Introduction

Inrecentyears,withthecontinuousdevelopmentofeconomy,people'slivingstandardscontinuetoimprove,ruraleconomicdevelopmentisalsoveryrapid,buttheruraleconomicdevelopmentandenvironmentaldevelopmentisnotsynchronized,seriousruralwaterpollution.Whilehightechnicalsewagetreatmentplants,suchascentralizedsewagetreatmentplantsareinvolvedinlargeinvestmentcosts,highoperatingcosts,Becauseofeconomicconstraints,suchsystemsarelesssuitableforlivestockfarmsandsmallcommunitiesinruralareas.Whilethemulti-media-soillayersystem（MSL）sewagetreatmentsystem,thisdecentralizedsewagetreatmentsystem,ithaslessinvestment,lowoperatingcosts,highhandlingload.Besides,theutilitymodelovercomesthedefectsofthepriorsoilpercolationwhichiseasytobeblockedfromthespacestructure.ThesewagetreatmentsystemisonekindofthepurificationtechnologyofseweragetreatmentsoildevelopedinJapanintwentiethCentury,thesoilsystemwillbemodularized,andthemoduleissetuparoundthewaterinthesoillayertoavoidclogging,andaddingnaturalorganicmaterialstosoilmodulescanimprovethepurificationabilityofthesystem.

TheMSLsystemconsistsofaPermeablelayer（PL）andasoilmixinglayerblock（SMB）,ThePermeablelayerisusuallycomposedoflargerparticlesfillerssuchasgravel,pumice,perliteandzeolite.Higherporositycaneffectivelypreventcloggingofthesoilwaterlayer.Atthesametime,theformationofaerobicenvironmentisconducivetoorganicdegradation.Themixedlayersoilismainlypackingsoilmixedwithother20%-30%othermaterialssuchasactivatedcarbon,wood,ironandothermaterialorsoilwithlocalresources.Theorganicmaterialaddedinthesoilmixedlayercanimprovethebiologicaldecompositionandadsorptioncapacityofthesystem,andcanalsoimprovethesupplyofhydrogenintheprocessofnitrogenremovalandpromotetheremovalofnitrogen.

TherearemanyresearchesonMSLsystemtreatingurbansewage,livestockwastewaterandriverwaterathomeandabroad.ResearchersinChina,YeHaietal[1]studiedtheeffectofsurfaceloadonpollutedriverwatertreatedbymulti-soil-layersystem.SongYing[2]hadstudiedthetreatmenteffectofmultimediumsoilinfiltrationsystemforturtlebreedingwastewater.ZouJun[3]alsopointedoutthatmulti-soil-layermaterialselectionwillhaveacertainimpactonthedomesticsewagetreatmentefficiency.Inforeigncountries,especiallyinJapan,ThailandandIndonesia,MSLsystemshavebeenusedtohandlevarioustypesofwastewater,butthedomesticofthistechnologyinsewagetreatmentinruralareasthereisnocomprehensivestudy,ThisarticlethroughtotheMSLsystemtechnologyprocessingruraldomesticsewageresearch,inordertoprovidesometechnicalsupportfortheMSLsysteminthepracticalapplicationofruralsewagetreatment.

2.1characteristicsofruralsewage

Foralongtime,China'spollutioncontrolonruralattentionandinvestmentfarlessthanthecity,96%ofthevillageswithoutdrainagepipenetworkandsewagetreatmentsystem,Therandomdischargeofdomesticsewagehasbecomeoneofthemainreasonsforthedeteriorationofwaterqualityinthebasin,andisalsoanimportantfactorcausingtheruralwaterenvironmentpollutionandlakeeutrophication.Atthesametime,itseriouslyaffectsthesafetyofproductionandlivingintheruralareas,andseriouslyaffectstheeconomicdevelopment.ThemainfeaturesofruralsewageinChinaare:

（1）Theamountishugeandincreasesyearbyyear.Statisticsshowthatin2002.Thereare3.205milliontonsofnationalruraldomesticsewagedailyemissions.Thetotalnitrogenemissionisabout283.1t,totalphosphorusdailyemissionisabout56.6t,basicallywithoutanytreatmentdirectlydischarged.

（2）Waterqualityandwaterquantityfluctuationarehuge.Ruralsewagewaterisnotstable,di