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aboveasizeof100populationequivalents30%oftheplantsaredesignedforlessthan1000inhabitants.wastewatertreatedintheplantsdesignedforlessthan1000p.e.accountsAcomparisonofthepollutionWaf.Sci.Tech.Vol.22,No.3/4,pp.1-8,1990.PrintedinGreatBritain.Allrightsreserved.0273-1223/90$0·00+·50Copyright©IAWPRCSMALLWASTEWATERTREATMENTPLANTSINSWITZERLANDMarkusBoller*andGieriDeplazes***SwissFederalInstituteforWaterResourcesandWaterControl(EAWAG),CH-8600Dubendorf,Switzerland**EnvironmentalProtectionOfficeoftheCantonoftheGrisons,CH-7001Chur,SwitzerlandABSTRACTInSwitzerland,theinstallationofsmalltreatmentplantsinruralareasisbeingandwillbeintensified.Inordertoremovethenumeroussmallpollutionsites,newguidelineshavebeenestablishedinwhichbasicinformationisgivenontheprocedureofhowtoconsiderlocalcircumstancesofwastewatercharacter-isticsandofhowtointegratelocalqualityrequirementsofthereceivingwaterintothedesignofsmallplants.Thestatisticsonsmalltreatmentplantsshowapreferentialapplicationforextendedaeration,RBCsandtrick-lingfilters.Duetothelackofskilledoperationandmaintenance,theper-formanceofsmalltreatmentplantsisnotalwayssatisfactory.Neweconomic,reliableandlessservice-demandingmethodsareincreasinglystudiedandapplied.KEYWORDSSmallwastewatersource;smalltreatmentplant;waterpollution;ruralareas;receivingwater;treatmenttechnologyINTRODUCTIONInSwitzerlandmorethan900wastewatertreatmentplantsserveabout90%ofthepopulation.Consideringthecountrywide.statisticsoftreatmentplants(p.e.)indifferentsizeclasses,themajorityofthetreatmentplantsareofrathersmallsiie,theamountofforonly2%ofthetotaldischarges.Therefore,thepollutioncausedbytheresidualsubstancescontainedinthelargerdischargeshasamUchstrongerimpactonthereceivingwatersthanthenumeroussmallandoftennotyettreatedwastew.atersourcesinruralareas.loadscouldleadtotheconclusionthatwastewatertreatmentofsmallsourcescanbeneglected.However,astudyinthealpineandpre-alpineregionswhereconnectionstocentraltreatmentplantsareoftennotfeasible,revealsnumerouspollutionspotsinsmallriversandcreeks.Localpollutionproblemslikesludgedeposition,heterotrophicbacteria,fungigrowth,aswellasoccasionalfishareobservedasacauseofsmalluntreatedsewagedischarges.Besidestheenlargementofexistingtreatmentplantsandtheapplicationofadvancedtechnologies(nitrification,contactfiltration)inthelargerplants,theenvironmentalprotectionagencieshaveputmucheffortintothetreatmentofsmallwastewatersources.3、管路敷设技术通1过管线0不仅2222可以解决吊顶层配置不规范高中资料试卷问题22，而且可保障2323各类管路习题到位。在管路敷设过程1中，要加强看255222护1关于管路高中资料试卷连接管口处理高中资料试卷弯扁度固定盒位置.保护层防腐跨接地线弯曲半径标高等，要求技术交底。管线敷设技术中包含线槽、管架等多项方式，为解决高中语文电气课件中管壁薄、接口不严等问题，合理利用管线敷设技术。线缆敷设原则：在分线盒处，当不同电压回路交叉时，应采用金属隔板进行隔开处理；同一线槽内，强电回路须同时切断习题电源，线缆敷设完毕，要进行检查和检测处理。4、电气课件中调试技术对全部高中资料试卷电气设备，在安装过程中以及安装结束后进行高中资料试卷调整试验；通电检查所有设备高中资料试卷相互作用与相互关系，根据生产工艺高中资料试卷要求，对电气设备进行空载与带负荷下高中资料试卷调控试验；对设备进行调整使其在正常工况下与过度工作下都可以正常工作；对于继电保护进行整核对定值，审核与校对图纸，编写复杂设备与装置高中资料试卷调试方案，编写重要设备高中资料试卷试验方案以及系统启动方案；对整套启动过程中高中资料试卷电气设备进行调试工作并且进行过关运行高中资料试卷技术指导。对于调试过程中高中资料试卷技术问题，作为调试人员，需要在事前掌握图纸资料、设备制造厂家出具高中资料试卷试验报告与相关技术资料，并且了解现场设备高中资料试卷布置情况与有关高中资料试卷电气系统接线等情况，然后根据规范与规程规定，制定设备调试高中资料试卷方案。5、电气设备调试高中资料试卷技术电力保护装置调试技术，电力保护高中资料试卷配置技术是指机组在进行继电保护高中资料试卷总体配置时，需要在最大限度内来确保机组高中资料试卷安全，并且尽可能地缩小故障高中资料试卷破坏范围，或者对某些异常高中资料试卷工况进行自动处理，尤其要避免错误高中资料试卷保护装置动作，并且拒绝动作，来避免不必要高中资料试卷突然停机。因此，电力高中资料试卷保护装置调试技术，要求电力保护装置做到准确灵活。对于差动保护装置高中资料试卷调试技术是指发电机一变压器组在发生内部故障时，需要进行外部电源高中资料试卷切除从而采用高中资料试卷主要保护装置。1980)etc.AnimportantfeatureoftheSwisslawforwaterpollutioncon-40p.e.andacheeseproductionplant.2M.BOLLERandG.DEPLAZESPROCEDUREFORWASTEWATERTREATMENTINRURALAREASInearlierdaystheaimofafastandcompletedisposalofwasteandrainwaterledtotheconstructionofmostlyprivateandshortdistancecombinedsewersystemsdischargingdirectlyintoanearbyreceivingwaterorinfil-tratingintotheunderground.Thesesystemsstillexistandareusuallythestartingpositionwhenplanningaredevelopment.Nowadays,theconsiderationofhygienic,aestheticandwaterpollutionaspectsdemandanewapproachforthedesignofwaterprotectionprojectsinruralareas,includingthewaterqualityrequirementsofthereceivingwater.Theprocedurethatshouldbefollowedstartswiththeanalysisofthelocalpollutionproblems.secondstepinformationiscollectedonwastewaterflowandloads.InaThediur-nalvariationsofthewastewaterflowandoftheconcentrationsofatleastorganicparametersareconsideredtobeanimportantprerequisiteforthedesignofanykindofsmalltreatmentsystem.Thenextstepcomprisestheformulationofthewaterqualityrequirementsforthetreatedeffluentbasedonqualitycriteriainthereceivingwater.Withtheinformationonlocalhydrologicalcircumstances,onwastewaterproductionandrequiredoutput,thedesignoftreatmentalternativescanbestudied.Thedecisionwhetherthetreatedeffluentisdischargedtoareceivingwaterorinfiltratedintotheundergroundandwheretheproducedsludgewillbedisposedof,willstronglyinfluencethechoiceofthetreatmentfacility.Themostimportantitemsofthedescribedprocedurearediscussedinmoredetail.BasicinformationAfteranexistingorapotentialpollutionproblemhasbeenidentified,quan-titativeandqualitativedataonsewagecharacteristicshavetobecollected.Usually,noinformationisavailablewhichleadsthedesignen