筑龍網(wǎng)Pleasecitethisarticleinpressas:ZhangJ,etal.,SustainableurbanseweragesystemanditsapplicationinChina,ResourcesConservRecycl(2007),doi:10.1016/j.resconrec.2006.10.001ARTICLEINPRESSRECYCL-1897；No.ofPages10Resources,ConservationandRecyclingxxx(2007)xxxxxxSustainableurbanseweragesystemanditsapplicationinChinaZhangJie,CaoXiang-Sheng,MengXue-ZhengKeyLaboratoryofBeijingforWaterQualityScienceandWaterEnvironmentRestorationEngineering,SchoolofCivilEngineering,BeijingUniversityofTechnology,Beijing100022,ChinaReceived4August2006；receivedinrevisedform30September2006；accepted4October2006AbstractChinaisfacingwatercrisis.Morethan400citiesarelackingenoughwaterresourcesandmorethanhalfriversarepolluted.Torealizesustainabledevelopmentinthe21stcentury,weshouldfirstprovideenoughwaterresourcestoeverypersonandkeepafriendly,leisurelywaterenvironment.Undertheideaofsustainability,aconceptforasustainableurbanseweragesystem(SUSS)isputforwardinthisarticle.Anurbanseweragesystemcannotonlybeabasicfacilityfordrainingrainwaterandwastewatertoprotecttheurbanenvironmentandpublicwaterbodies,butmustalsocontributetotherestorationofthewaterenvironmentinordertomaintainahealthysocialwatercycle.ASUSSshouldbethebasisforurbanwaterreuseandrecyclingaswellasthefocusofwaterresourceregenerationinawatershedandthecentreoftherecyclingofnutrients.SUSSpracticesintheShenzhenSpecialEconomicZoneandtheBeijingregioninChinaareintroduced.2006ElsevierB.V.Allrightsreserved.Keywords:Water；Resources；Wastewater；Reuse；Sustainability；China1.IntroductionWaterresourcesinChinaarescarce.AccordingtoChinaBulletinofWaterResourcespublishedbyChinaMinistryofWaterResources,in2004,thetotalamountofwaterCorrespondingauthorat:No.100,Pingleyuan,ChaoyangDistrict,CollegeofCivilEngineering,BeijingUniversityofTechnology,Beijing100022,China.Tel.:+861067392579；fax:+861067392579.E-mailaddress:(X.-S.Cao).0921-3449/$seefrontmatter2006ElsevierB.V.Allrightsreserved.doi:10.1016/j.resconrec.2006.10.001筑龍網(wǎng)Pleasecitethisarticleinpressas:ZhangJ,etal.,SustainableurbanseweragesystemanditsapplicationinChina,ResourcesConservRecycl(2007),doi:10.1016/j.resconrec.2006.10.001ARTICLEINPRESSRECYCL-1897；No.ofPages102J.Zhangetal./Resources,ConservationandRecyclingxxx(2007)xxxxxxresourcesinChinais2.4131013m3.Itisequalto1856m3percapitaperyear.Amongthese,23%,thatis5.5481012m3,wasusedforagricultural,industryanddomesticactiv-ities.Atthesametime,6930108m3wastewaterwasdischargedfromChinesecities.Nomorethanhalfamountsweresubjecttothesecondarytreatment.MorethanhalfriversinChinaareterriblypolluted(Gaoetal.,2006).Totacklethewatercrisis,thegovernmentofChinahadpublishedalotofregulations；researcheshadsuggestedalotofstrategies；engineershadplannedandconstructedmanywatersuppliesandwastewatertreatmentprojects(Baietal.,2006；HeandXing,2006；Panetal.,2006).ButwiththedevelopmentofChineseeconomics,waterresourcesisbecomingincreasingdeficientandthequalityofenvironmentconstantlybecomingworseinmostregionsofChina.AnewwateruseandtreatmentstrategymustbeestablishedtotacklethewaterproblemsofChinaandtorealizethesustainabledevelopment.Thefunctioningofurbanseweragesystemsbasedontraditionalconceptsisnotsustainable；itneedstobechanged.Anurbanseweragesystemcannotonlybeabasicfacilityfordrainingrainwaterandwastewatertoprotecttheurbanenvironmentandpublicwaterbodies,butmustalsocontributetotherestorationofthewaterenvironmentinordertomaintainahealthysocialwatercycle.Asocialwatercycleisdefinedasasystemthatincludesdrawingwaterfromnaturalbodies,utilizingitanddischargingitbacktothewaterbodies(Zhang,2001).Ahealthysocialwatercyclemeansthatweshoulddrawwatermoderately,usewatercarefully,purifyandreusewastewaterdeliberately.Weshouldensurethatthewaterutilizationintheupperreachesoftheriversdoesnotaffectthefunctionofwaterbodiesinthelowerreachesoftherivers.Theultimateaimistorestoreormaintainahealthywaterenvironmentforacityorriverbasinandeventuallyachievethesustainableutilizationofwaterresources.Ahealthysocialwatercycleisalsoanessentialcomponentofestablishingacitythatrecycles(Guanetal.,2004).Theaimofthisarticleistodiscussfunctionanddesignconsiderationsforasustainableurbanseweragesystemusingconceptsassociatedwithahealthywatercycle.Inthispaperwewillintroducesomeurbanplanningsuggestionstopromotesuchahealthywatercycle.2.Thedevelopmentofsustainableurbanseweragesystems2.1.HistoryofurbanseweragesystemTheearliesturbanseweragesystemswereconstructedtoonlytransportexcessoverlandrainwaterasquicklyaspossiblefromacitytoriversthatweredownstreamfromthecity(Aminuddinetal.,2000；Angelakisetal.,2005).Theflushtoiletwasinventedinthe18thcenturyandbecamewidespreadthroughoutthecitiesofEuropeinthe19thcentury.Thewidespreaduseofflushtoiletsimprovedthesanitationconditionsofurbanresidents,buttheamountofwatersupplyandseweragerequiredasaresultincreaseddramatically.Atthistime,thesewerandrun-offseweragesystemswereconstructedasacombinedseweragesys-tem.Thefunctionoftheurbanseweragesystemchangedtothiscombinedsystemtoprotecttheinhabitantsfrombacterialinfectionasthemajorcomponentofsanitaryengineering.However,riversandlakesnearcitiesbecameterriblypollutedduringthisperiodbecauseoflargeamountofuntreatedwastewatercontainingfecesandurine.Thepollutionofthe筑龍網(wǎng)Pleasecitethisarticleinpressas:ZhangJ,etal.,SustainableurbanseweragesystemanditsapplicationinChina,ResourcesConservRecycl(2007),doi:10.1016/j.resconrec.2006.10.001ARTICLEINPRESSRECYCL-1897；No.ofPages10J.Zhangetal./Resources,ConservationandRecyclingxxx(2007)xxxxxx3RhineRiverinthe20thcenturyisatypicalillustration(Carel,1998).Theimprovementsinlivingconditionsofcityinhabitantswereobtainedatthepriceofpollutionofthewaterenvironment.Researchandpracticesofwastewatertreatmenttechnologybeganintheearly20thcen-turywithastartingconditioninwhichtheriversandlakeswerebadlypolluted.Duringthepastcentury,thetechnologiesassociatedwithwastewatertreatmentadvanceddramati-callywiththeremovalofpollutants,includingsuspendedsolidsandorganics,subsequentlynitrogenandphosphatesandfinallymicropollutants,suchasdisinfectionbyproductsandhormone-likesubstances(Henze,1997).Currently,thefunctionsofurbanseweragesystemsareasfollows:(1)transportrainwaterandwastewateroutsideacityassoonaspossibletoprotectagainstfloodsandpreventthespreadofepidemics；(2)treatmunicipalwastewatertoreachorexceedthestandardsofstateorlocalregulations.2.2.Thepatternofsustainableurbanseweragesystemsinthe21stcenturyTheabove-mentionedfunctionsofurbanseweragesystemswereformedunderthehypothesisthatwaterresourceswereabundantenoughtosplurgeandthattheriversorlakesthatwastewaterwasdumpedintohadenoughcapacityforself-purification.Thishypoth-esiswassupportedwhenpopulationswerenotverylargeorcentralizedandindustrieswereunderdeveloped.Asindustriesdeveloped,peoplebecameincreasinglycentralizedandmetropolitanareasemerged.Atthistimetraditionalurbanseweragesystemscouldonlyprotecttheareawithincities.Theregionsaroundthecitieswerebadlypollutedbywastewaterandotherwastesproducedbythetownspeople.Fromtheperspectiveoftherestorationofentirewatersheds,urbanseweragesystemsarepartoftheoverallhydrologicalcycle.Thefunctionofurbanseweragesystemsshouldbereevaluatedandnewmissionsshouldbeespoused.Urbanseweragesystemsshouldplayanimportantroleinahealthywatercycleandinsustainableurbanconstruction.Ifwecompareacitytoahumanbody,watercanbethoughtofasblood.Thewatersupplysystemisanalogoustothearteriesandthewastewatersystemisanalogoustotheveins.Awastewatertreatmentplantcouldbeconsideredasanalogoustotheliverbecauseoftheplantsroleinpurifyingurbanwastewater.Urbanseweragesystemsareofnecessityresponsibleforwastewatercollection,transportation,purificationandreclamation.Anurbanseweragesystemisthekeyfactorforclosingtheurbanwatercycle.Thefunctionofanurbanseweragesysteminthe21stcenturyshouldshiftfromtradi-tionalwaterloggingpreventiontotheestablishmentofwastewaterrecycling,sustainableutilizationofwaterresourcesandwatershedrestoration.Thisnewurbanseweragesystemiscalledasustainableurbanseweragesystem(SUSS)inthisarticleandasketchofitskeyfeaturesisshowninFig.1.AtypicalSUSShasfourmodernfeaturesdescribedasfollows:(1)Itisthebasisforurbanwaterreuseandrecycling.ASUSShasthedutyofpro-ducingreclaimedwastewaterasasteadysecondaryurbanwaterresource.Reclaimedwastewatercanbeusedascoolingwaterforindustry,irrigationwaterforlandscaping,flowingwaterforrivuletregenerationandforanyotherapplicationwherenon-potablewatermaybeused.Alargevolumeofreclaimedwastewatercouldreducefreshwaterexploitation,andthuspromoteahealthywatercycle.筑龍網(wǎng)Pleasecitethisarticleinpressas:ZhangJ,etal.,SustainableurbanseweragesystemanditsapplicationinChina,ResourcesConservRecycl(2007),doi:10.1016/j.resconrec.2006.10.001ARTICLEINPRESSRECYCL-1897；No.ofPages104J.Zhangetal./Resources,ConservationandRecyclingxxx(2007)xxxxxxFig.1.Sketchofasustainableurbanseweragesystem.(2)WaterresourceregenerationinawatershedhingesonSUSS.Inawatershed,wastewaterdrainedfromuprivercitiesflowsintodownrivercities.OutflowofupriverSUSSwouldbeapartofthewaterresourceofdownrivercitiesthroughoutanentirewatershed.EachSUSSshouldhavethiswaterresourceregenerationcapacity.(3)SUSSiscentraltonutrientrecycling.Asaproductofwastewatertreatment,sludgeshouldbetreatedproperlyandreturnedtofarmlandasfertilizer.Nitrogenandphos-phatesinwastewatershouldberecoveredasfertilizerduringthewastewatercollection,transportationandtreatmentprocess.SUSSplaysanimportantroleinthereparationofnatura