污水處理常用方法

////污水處理常用方法1城市污水處理的重要性和迫切性1theimportanceandurgencyofurbansewagetreatment我國淡水資源十分短缺，人均擁有量2300m3,相當于世界人均水平的1/4,居世界110位。1997年起,全國城市污水排放量占廢水排放總量的比例接近45%，改變了我國水污染治理工作一直以工業(yè)廢水治理為主的局面，開始加強城市污水的綜合治理工作。1999年我國城市污水污染負荷首次超過了工業(yè)廢水污染負荷，我國水污染控制重點已經(jīng)從工業(yè)點源污染為主的控制，逐步轉(zhuǎn)變?yōu)橐猿鞘形鬯廴緸橹鞯目刂?。?jù)《2003年中國環(huán)境狀況公報》公布,2003年，全國廢水排放總量為460億噸，其中城市生活污水排放量247.6億噸,占污水排放總量的53.8%。廢水化學需氧量(COD)排放總量1333萬噸,其中生活污水COD排放821.7萬噸,占廢水COD排放總量的61.6%，由此可見,目前我國的水污染形勢嚴峻，特別是城市污水的排放對地表水和地下水水質(zhì)的影響顯得更加突出。據(jù)有關資料統(tǒng)計,全國近80%的生活污水未經(jīng)處理，直接排入江河湖海,年排污量達400億m3,造成全國1/3以上的水域受到污染。專家指出，水污染加劇了水資源的短缺，直接威脅著飲用水的安全和人民群眾的健康，影響到工農(nóng)業(yè)生產(chǎn)和農(nóng)作物安全造成的經(jīng)濟損失約為GNP的1.5%~3%，水污染已成為不亞于洪災、旱災甚至更為嚴重的災害。未來城市的最大危害就是污水。造成我國水污染嚴重的主要原因之一是由于全國城市污水處理率較低，使大量的城市污水未經(jīng)處理而直接外排，導致了嚴重的水污染，并加劇了水資源的短缺。加上隨著城市化和工業(yè)化進程的加快，城市污水產(chǎn)生量不斷增大，使得水環(huán)境污染日益嚴重。城市污水處理的嚴重滯后，已經(jīng)成為影響我國區(qū)域水污染防治目標實現(xiàn)的一個重要因素，并且嚴重制約了城市社會經(jīng)濟的可持續(xù)發(fā)展。國家專門就城市污水處理問題頒布了一系列政策及技術(shù)規(guī)定,制訂城市治污達標的“時間表”，加快建設城市污水集中處理設施刻不容緩。Thereisashortageoffreshwaterresourcesinourcountry,percapita2300m3,equivalenttoaquarteroftheworldpercapitalevel,theworldin110.Since1997,thenationalurbansewageemissionsaccountedfornearly45%ofthewastewateremissions,tochangethegovernanceofwaterpollutioninourcountryworkhasbeenmainlyofindustrialwastewatertreatment,beganworkingasastrengtheningofthecomprehensiveadministrationoftheurbansewage.UrbansewagepollutionloadforthefirsttimeinChinain1999morethantheindustrialwastewaterpollutionload,thekeytowaterpollutioncontrolinChinaismainlyfromtheindustrialpointsourcepollutioncontrol,graduallyintoapredominantlyurbanwastewaterpollutioncontrol.Accordingtothe2003Chinaenvironmentalstatusbulletinpublished,in2003,thenationalwastewaterdischargeforatotalof46billiontonsofurbansewageemissionsby247.600milliontons,accountingfortotalsewagedischargeof53.8%.Wastewaterchemicaloxygendemand(COD)emissionsof13.33milliontons,includingsewageCODemissionsof8.217milliontons,accountingforwastewaterCODemissionsof61.6%,thisshows,thegrimsituationofwaterpollutioninourcountry,especiallyurbansewageemissionsimpactonsurfacewaterandgroundwaterqualityappearsmoreprominent.Accordingtorelevantstatistics,thenearly80%oftheuntreatedsewage,directlydischargedintoriversandlakes,annualemissionsof40billionm3,causingmorethanathirdofthewaterispolluted.Expertspointoutthatthewaterpollutionaggravatedtheshortageofwaterresources,directlythreattodrinkingwatersafetyandpeople'shealth,affecttheeconomiclossescausedbytheindustrialandagriculturalproductionandcropsafetyaboutGNPof1.5%~3%,waterpollutionhasbecomeadisastersasfloods,droughtsandevenmoreserious.Theworsteffectsofthefuturecity'ssewage.Causeseriouswaterpollutioninourcountryoneofthemainreasonsisduetothenationalurbanwastewatertreatmentrateislow,makealotofuntreatedsewageanddirectdischarge,hasledtoseriouswaterpollution,andexacerbatingwatershortages.Pluswiththespeedingupofurbanizationandindustrialization,urbansewagequantityincreasesunceasingly,makesthewaterenvironmentpollutionisbecomingmoreandmoreserious.Thelagofurbansewagetreatment,hasbecomeChina'sregionalwaterpollutionpreventiongoalsisoneofthemostimportantfactors,andseriouslyrestrictedthecitysocialeconomysustainabledevelopment.Countryspecializesinurbansewagedisposalproblemhasissuedaseriesofpoliciesandtechnicalprovisions,toformulate"timeline"oftheurbanpollutionstandard,soitisurgenttospeeduptheconstructionofurbansewageconcentratedtreatmentfacilities.2.污水處理常用方法探討2.Sewagetreatmentmethodsdiscussedinthispaper2.1活性污泥法。theactivatedsludgeprocess.長期以來，城市生活污水多采用活性污泥法，它是世界各國應用最廣的一種生物處理流程，具有處理能力高，出水水質(zhì)好的優(yōu)點。該方法主要由曝氣池、沉淀池、污泥回流和剩余污泥排放系統(tǒng)組成。廢水和回流的活性污泥一起進入曝氣池形成混合液。曝氣池是一個生物反應器，通過曝氣設備充入空氣，空氣中的氧溶入混合液，產(chǎn)生好氧代謝反應,且使混合液得到足夠的攪拌而呈懸浮狀態(tài)，這樣，廢水中的有機物、氧氣同微生物能充分接觸反應。隨后混合液進入沉淀池，混合液中的懸浮固體在沉淀池中沉下來和水分離，流出沉淀池的就是凈化水。沉淀池中的污泥大部分回流,稱為回流污泥，回流污泥的目的是使曝氣池內(nèi)保持一定的懸浮固體濃度，也就是保持一定的微生物濃度。曝氣池中的生化反應引起微生物的增殖，增殖的微生物量通常從沉淀池中排除，以維持活性污泥系統(tǒng)的穩(wěn)定運行，這部分污泥叫剩余污泥。活性污泥除了有氧化和分解有機物的能力外，還要有良好的凝聚和沉降性能，以使活性污泥能從混合液中分離出來，得到澄清的出水。Foralongtime,citylifesewageusedmoreactivesludgemethod,itisoneofthecountriesaroundtheworldthemostwidelyusedbiologicaltreatmentprocess,withhighprocessingcapacity,waterqualitygood.Thismethodismainlycomposedofaerationtank,tank,returnsludgeandsludgedischargesystem.Wastewaterandbackflowactivatedsludgeinaerationtanktoformmixturetogether.Aeratorisabioreactor,fillingtheairthroughtheaerationequipment,oxygenintheairintothemixture,aerobicmetabolicreactions,andmadethemgetenoughmixturemixingandastateofsuspension,thisway,organicmatterinwastewatercanbefullycontactreaction,oxygenwithmicroorganisms.Thenmixtureintothesedimentationtank,themixturesuspendedsolidsunkdowninthesedimentationtankandwaterseparation,flowsedimentationtankiscleanwater.Mostrefluxsludgeinsedimentationtank,calledbackflowsludge,backflowsludgeisthepurposeofkeepingtheinterioroftheaerationtankinacertainconcentrationofsuspendedsolid,alsoistomaintainacertainconcentrationofmicroorganisms.Biochemicalreactionscausedbymicrobialproliferationintheaerationtank,theproliferationofmicroorganismquantityusuallyexcludedfromthesedimentationtank,inordertomaintainthestableoperationoftheactivatedsludgesystem,thispartofthesludgeexcesssludge.Activatedsludgebesideshastheabilitytooxidationanddecompositionoforganicmatter,alsohavegoodcoagulationandsedimentationperformance,sothattheactivatedsludgecanbeseparatedfromthemixtureofwaterclarification.由于污水處理是一項側(cè)重于環(huán)境效益和社會效益的工程，因此在建設和實際運行過程中常受到資金的限制，使得治理技術(shù)與資金問題成為我國水污染治理的“瓶頸氣歸納起來,目前在城市生活污水處理研究和應用領域，普遍存在的問題有：(1)采用傳統(tǒng)的活性污泥法，往往基建費、運行費高,能耗大，管理復雜,易出現(xiàn)污泥膨脹現(xiàn)象;設備不能滿足高效低耗的要求；(2)隨著污水排放標準的不斷嚴格，對污水中氮、磷等營養(yǎng)物質(zhì)的排放要求較高，傳統(tǒng)的具有脫氮除磷功能的污水處理工藝多以活性污泥法為主，往往需要將多個厭氧和好氧反應池串聯(lián)，形成多級反應池，通過增加內(nèi)循環(huán)來達到脫氮除磷的目的，這勢必增加基建投資的費用及能耗,并且使運行管理較為復雜；(3)目前城市污水的處理多以集中處理為主，龐大的污水收集系統(tǒng)的投資遠遠超過污水處理廠本身的投資，因此建設大型的污水處理廠，集中處理生活污水，從污水再生回用的角度來說不一定是唯一可取的方案。Duetowastewatertreatmentisafocusontheenvironmentalbenefitsandsocialbenefitsoftheproject,soinconstructionandtheactualoperationprocessislimitedbyfunding,managementtechnologyandcapitalproblemsbecomethe"bottleneck"ofwaterpollutioncontrolinChina.Sumup,atpresentinthefieldofurbansewagetreatmentresearchandapplication,commonproblemsare：(1)usingthetraditionalactivatedsludgeprocess,oftenJiJianFei,highoperatingcost,largeenergyconsumption,managingcomplex,causingsludgebulkingphenomenon;Equipmentcannotmeettherequirementsofhighefficiencylowenergyconsumption;(2)withthesewagedischargestandardstrictly,nutrientssuchasnitrogenandphosphorusinwastewateremissionsofthedemandishigher,thetraditionalwhichhasthefunctionofdenitrificationandphosphorusremovalofwastewatertreatmentwithactivatedsludgeprocessisgivenpriorityto,moreoftenrequiremultipleanaerobicanaerobic-aerobicreactionpoolseries,multistagereactionpoolformation,byincreasingtheinnerlooptoachievethepurposeofnitrogenandphosphorus,andthiswillinevitablyincreasethecostofinfrastructureinvestmentandenergyconsumption,andoperationmanagementmorecomplex;(3)thecurrenturbansewagetreatmentmainlyfocusonmore,largesewagecollectionsystemoftheinvestmentismuchhigherthantheinvestmentofsewagetreatmentplantitself,sotheconstructionoflargesewagetreatmentplant,sewageconcentratedprocessing,fromthepointofviewofwastewaterregenerationrecyclearenotnecessarilytheonlydesirable.因此，如何使城市污水處理工藝朝著低能耗、高效率、少剩余污泥量、最方便的操作管理，以及實現(xiàn)磷回收和處理水回用等可持續(xù)的方向發(fā)展，已成為目前水處理技術(shù)研究和應用領域共同關注的問題。這要求污水處理不應僅僅滿足單一的水質(zhì)改善,同時也需要一并考慮污水及所含污染物的資源化和能源化問題，且所////采用的技術(shù)必須以低能耗和少資源損耗為前提。Therefore,howtomakethecitysewagetreatmentcrafttowardlowenergyconsumption,highefficiency,lesssurplussludgevolume,themostconvenientoperationmanagement,andrealizethephosphorusrecoveryandtreatedwaterrecyclinginthedirectionofsustainabledevelopment,hasbecomethecurrentwatertreatmenttechnologyresearchandapplicationareasofcommonconcern.Thisrequiressewagetreatmentshouldnotonlymeetthewaterqualityimprovementofthesingle,atthesametimealsoneedtobeconsideredalongwithallthesewageofthepollutantsandtheproblemofresourceandenergy,andthetechnologymustbeadoptedonthepremiseoflowenergyconsumptionandlessresourcedepletion.2.2生物膜法。biofilmmethod.在污水生物處理的發(fā)展和應用中,活性污泥和生物膜法一直占據(jù)主導地位。生物膜法主要用于從廢水中去除溶解性有機污染物，主要特點是微生物附著在介質(zhì)“濾料”表面,形成生物膜,污水同生物膜接觸后，溶解的有機污染物被微生物吸附轉(zhuǎn)化為H2O、CO2、NH3和微生物細胞物質(zhì),污水得到凈化，所需氧化一般直接來自大氣。生物膜法處理系統(tǒng)適用于處理中小規(guī)模的城市廢水，采用的處理構(gòu)筑物有高負荷生物濾池和生物轉(zhuǎn)盤，生物濾池在我國南方更為適用。隨著新型填料的開發(fā)和配套技術(shù)的不斷完善,與活性污泥法平行發(fā)展起來的生物膜法處理工藝在近年來得以快速發(fā)展。由于生物膜法具有處理效率高、耐沖擊負荷性能好、產(chǎn)泥量低、占地面積少、便于運行管理等優(yōu)點在處理中極具競爭力塑料土工格柵。Inthedevelopmentandapplicationofwastewaterbiologicaltreatment,activatedsludgeandbiologicalmembranemethodhasbeendominant.Biologicalmembranemethodismainlyusedtoremovesolubleorganicpollutantsfromwastewater,themaincharacteristicsismicrobialadhesionoverthesurfaceofthemedium"liao",biofilmformation,wastewaterwithbiologicalmembraneaftercontact,dissolvedorganicpollutantsbymicroorganismsintoH2O,CO2,NH3adsorptionandmicrobialcellmaterial,purifiedwater,theoxidationgenerallydirectlyfromtheatmosphere.Biologicalmembranemethodprocessingsystemissuitableforsmallandmedium-sizedcitiesinwastewatertreatment,usingbiologicalfilterprocessingstructureswithhighloadandbiologicalturnplate,biologicalfilterismoreapplicableinthesouthofChina.Asthedevelopmentofnewtypefillerandsupportingtechnologycontinuestoimprove,andactivatedsludgemethoddevelopedparalleltothebiologicalmembranemethodprocessingtechnologyrapidlydevelopedinrecentyears.Duetothebiologicalmembranemethodprocessingwithhighefficiency,goodimpactresistanceloadperformance,lowsludgeproductionvolume,coversanareaofless,easytooperationandmanagementadvantages,highlycompetitiveintheprocessing.2.3氧化法。oxidationmethod.氧化法是目前廣泛采用并極具發(fā)展?jié)摿Φ某鞘猩钗鬯A處理方法之一。根據(jù)氧化劑的種類及反應器的類型,氧化法可分為化學氧化法、催化氧化法、（催化）濕式氧化法,光催化氧化法、超臨界氧化法等。起重機配件化學氧化法雖然操作簡單，但由于其處理效果并非十分理想，而且由于其運行成本較高，因此，在城市生活污水處理應用中使用并不很多。為了達到提高處理效果，同時降低運行成本的目的，人們開發(fā)了一些其他的氧化技術(shù)。光催化氧化法設備簡單、運行條件溫和、氧化能力強、殺菌作用強、處理徹底，因此，在水的深度處理及對難生物降解的有機廢水的處理具有極好的應用前景，目前已成為國內(nèi)外非?；钴S的研究課題，有專家預測,氧化法將成為21世紀廢水處理中重要的方法之一水泥制管機。Oxidationmethodiswidelyusedatpresentanddevelopmentpotentialofoneofthecitylifesewagepretreatmentmethod.Dependingonthetypeofoxidantandreactortypes,oxidationprocesscanbedividedintochemicaloxidation,catalyticoxidation,catalyticwetoxidation,photocatalyticoxidation,supercriticaloxidation,etc.Chemicaloxidationmethodwhiletheoperationissimple,butasaresultoft