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(dāng)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(qiáng)城市污水的綜合治理工作。1999年我國城市污水污染負(fù)荷首次超過了工業(yè)廢水污染負(fù)荷，我國水污染控制重點(diǎn)已經(jīng)從工業(yè)點(diǎn)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(bào)》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(xué)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(shì)嚴(yán)峻，特別是城市污水的排放對(duì)地表水和地下水水質(zhì)的影響顯得更加突出。據(jù)有關(guān)資料統(tǒng)計(jì),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(dá)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(jì)損失約為GNP的1.5%~3%，水污染已成為不亞于洪災(zāi)、旱災(zāi)甚至更為嚴(yán)重的災(zāi)害。未來城市的最大危害就是污水。造成我國水污染嚴(yán)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(dǎo)致了嚴(yán)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(jìn)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(yán)重。城市污水處理的嚴(yán)重滯后，已經(jīng)成為影響我國區(qū)域水污染防治目標(biāo)實(shí)現(xiàn)的一個(gè)重要因素，并且嚴(yán)重制約了城市社會(huì)經(jīng)濟(jì)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(dá)標(biāo)的“時(shí)間表”，加快建設(shè)城市污水集中處理設(shè)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(yīng)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(diǎn)。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(jìn)入曝氣池形成混合液。曝氣池是一個(gè)生物反應(yīng)器，通過曝氣設(shè)備充入空氣，空氣中的氧溶入混合液，產(chǎn)生好氧代謝反應(yīng),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(jī)物、氧氣同微生物能充分接觸反應(yīng)。隨后混合液進(jìn)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(yīng)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(yùn)行，這部分污泥叫剩余污泥?；钚晕勰喑擞醒趸头纸庥袡C(jī)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(xiàng)側(cè)重于環(huán)境效益和社會(huì)效益的工程，因此在建設(shè)和實(shí)際運(yùn)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(yīng)用領(lǐng)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(fèi)、運(yùn)行費(fèi)高,能耗大，管理復(fù)雜,易出現(xiàn)污泥膨脹現(xiàn)象;設(shè)備不能滿足高效低耗的要求；(2)隨著污水排放標(biāo)準(zhǔn)的不斷嚴(yán)格，對(duì)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(gè)厭氧和好氧反應(yīng)池串聯(lián)，形成多級(jí)反應(yīng)池，通過增加內(nèi)循環(huán)來達(dá)到脫氮除磷的目的，這勢(shì)必增加基建投資的費(fèi)用及能耗,并且使運(yùn)行管理較為復(fù)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(yuǎn)遠(yuǎn)超過污水處理廠本身的投資，因此建設(shè)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(shí)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(yīng)用領(lǐng)域共同關(guān)注的問題。這要求污水處理不應(yīng)僅僅滿足單一的水質(zhì)改善,同時(shí)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(yīng)用中,活性污泥和生物膜法一直占據(jù)主導(dǎo)地位。生物膜法主要用于從廢水中去除溶解性有機(jī)污染物，主要特點(diǎn)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(jī)污染物被微生物吸附轉(zhuǎn)化為H2O、CO2、NH3和微生物細(xì)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(fù)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(fù)荷性能好、產(chǎn)泥量低、占地面積少、便于運(yùn)行管理等優(yōu)點(diǎn)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(yù)處理方法之一。根據(jù)氧化劑的種類及反應(yīng)器的類型,氧化法可分為化學(xué)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(jī)配件化學(xué)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(yùn)行成本較高，因此，在城市生活污水處理應(yīng)用中使用并不很多。為了達(dá)到提高處理效果，同時(shí)降低運(yùn)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(shè)備簡單、運(yùn)行條件溫和、氧化能力強(qiáng)、殺菌作用強(qiáng)、處理徹底，因此，在水的深度處理及對(duì)難生物降解的有機(jī)廢水的處理具有極好的應(yīng)用前景，目前已成為國內(nèi)外非?；钴S的研究課題，有專家預(yù)測(cè),氧化法將成為21世紀(jì)廢水處理中重要的方法之一水泥制管機(jī)。Oxidationmethodiswidelyusedatpresentanddevelopmentpotentialofoneofthecitylifesewagepretreatmentmethod.Dependingonthetypeofoxidantandreactortypes,oxidationprocesscanbedividedintochemicaloxidation,catalyticoxidation,catalyticwetoxidation,photocatalyticoxidation,supercriticaloxidation,etc.Chemicaloxidationmethodwhiletheoperationissimple,butasaresultoft