環(huán)境科學(xué)和工程專業(yè)英語翻譯

./第四單元閱讀材料：ReadingMaterial:AnalyticalTechniqueandMethodology第八單元：空氣污染物的來源和類型第八單元ReadingMaterial:TypeandSourcesofAirPollutants[IIJ閱讀材料：空氣污染物的類型和來源〔ⅡWhatarePCBs?什么是多氯聯(lián)苯？Thereare209possiblechlorinatedbiphenyls,ranginginphysicalcharacteristics.大概有209種氯化聯(lián)苯,其物理性質(zhì)不同。Themono-anddichlorobiphenyls<27323-18-8>,<25512-42-9>arecolorlesscrystallinecompoundsthatwhenburnedinairgiverisetosootandhydrogenchloride.一氯聯(lián)苯和二氯聯(lián)苯〔27323-18-8,〔25512-42-9是無色晶體的化合物,當(dāng)它們在空氣中燃燒會產(chǎn)生煙塵和氯化氫。Themostimportantproductsaretri-chlorobiphenyls,tetrachlorobiphenyls,pentachlorobiphenylsand/orhexachlorobiphenyls.最重要的產(chǎn)品是三-氯化聯(lián)苯,四氯聯(lián)苯,五氯聯(lián)苯和/或六氯聯(lián)苯。Chlorinatedbiphenylsaresolubleinmanyorganicsolventsandinwateronlyintheppmrange.多氯聯(lián)苯可溶于有機(jī)溶劑和僅在水的百萬分之一ppm〔partpermillion的范圍內(nèi)溶解。Althoughchemicallystable<includingtooxygenoftheair>theycanbehydrolyzedtooxybiphenylsunderextremeconditionsformingtoxicpolychlorodibenzofurans.氯化聯(lián)苯易溶于在許多有機(jī)溶劑和水只有在的范圍內(nèi)的可溶性。雖然化學(xué)穩(wěn)定性〔包括空氣中的氧氣但是在一定條件下,多氯聯(lián)苯可水解氧化成二氧化苯極端條件下形成的有毒的多氯代苯并二噁英。ThePCBclassofcompoundsreceivedsubstantialattentionandnotorietywhenin1968,inJapan,accidentalpoisoningoccurredbycookingriceinbranoilcontaminatedbyPCBs.在1968年,多氯聯(lián)苯類化合物受到實質(zhì)性的的關(guān)注和得到臭名,日本用受到多氯聯(lián)苯污染的米糠油做飯的意外中毒事件。Over1000patientssufferedfromvariousmorbidsymptoms.超過1000例患者出現(xiàn)各種病態(tài)癥狀。AsimilarpoisoningoccurredinTaiwanin1979.CausativeagentswereconsideredtobecoconaminantsofPCBssuchaspoly-chlorinateddibenzofuransthataresecondarilyformedduringheatingofPCBscongenersincommercialPCBmixturesandrequireasecondlookatPCBtoxicity.1979年XX有一個類似的中毒事件。病原體被認(rèn)為是如多氯二苯并呋喃的多氯聯(lián)苯,其次是PCBs多氯聯(lián)苯同系物在商業(yè)PCB混合物在加熱過程中形成的,需要第二次看看PCB的毒性。PCBregulation多氯聯(lián)苯的管理BecauseofconcernsregardingPCB'shealtheffectsandevidenceofpresenceandpersistenceintheenvironmentfurthermanufactureofthechemicalwasbannedunderThe1976ToxicSubstanceControlAct.由于擔(dān)心多氯聯(lián)苯對健康的影響和證明存在以及持續(xù)在環(huán)境中會進(jìn)一步制造化學(xué)物質(zhì)的,在1976年美國有毒物質(zhì)控制法中被禁止了。PCBregulationsprovidedeadlinesforremovalofmostin-usecapaci-torsandtransformerscontainingPCBs·andlimittimeforstoragefordisposaltooneyear.多氯聯(lián)苯的管理提出最后期限為了最大去除使用電容器和變壓器逗留的多氯聯(lián)苯和限制儲存一年就要處理。EPAhasallowedcontinueduseofPCBsinelectricaltransformersandcapacitorswhentheagencydidnotposeunreasonablerisk.當(dāng)經(jīng)銷產(chǎn)品不會產(chǎn)生過度的危險時,環(huán)境保護(hù)局允許繼續(xù)使用含多氯聯(lián)苯的電子電容器和變壓器。Capacitors,exceptthoseinisolatedareasshouldhavebeenremovedbyOctober1988,andtransformersofacertainsizeinornearcommercialbuildingsshouldberemovedbyOctober1990.電容器,除了那些分散地方的應(yīng)該被移走在1988年10月之后,變壓器的某一些型號和靠近商業(yè)建筑的應(yīng)該被移走在1990年10月后。EPAregulationsrequirethatPCBstakenoutofservicebedisposedofeitherbyspeciallydesignedhightemperatureincineratorsneededtobreakhighconcentrationsofPCBstoharm-lesscomponentsorbyalternatedestructionmethodsapprovedbytheagency.EnvironmentalProtectionAgency美國環(huán)保署,法規(guī)要求PCB服務(wù)多氯聯(lián)苯或者處置的,通過特別設(shè)計的高溫焚化爐需要打破高濃度的多氯聯(lián)苯的無害組件或替代由該機(jī)構(gòu)批準(zhǔn)的銷毀方法。Oilscontami-natedwithlowconcentrations<50-500ppm>maybedisposedbyhighefficiencyboilers.低濃度〔50?500PPM污染的油可以通過高效率的鍋爐處理。ThelimitednumberofincineratorsapprovedforPCBincinerationandthehighcostofbuildingadditionalincineratorshavegivenincentiveforalternatedestructionmethods.AlternatetechnologiesmustbecapableofoperatingaseffectivelyasEPA'sincinerationeffi-ciency.批準(zhǔn)用于焚燒多氯聯(lián)苯的焚燒爐數(shù)量被限制和成本高且附有焚燒爐的建筑鼓勵使用一一分解的方法。選擇的技術(shù)的運(yùn)轉(zhuǎn)效率必須能夠達(dá)到環(huán)境保護(hù)局的焚燒效率。PCBsinelectricaltransformers多氯聯(lián)苯的電流體變壓器Therewere304millionlbofPCBsusedaselectricalfluidinapproximately150000askarel<non-flammableelectricalfluid>transformersintheUnitedStates.在美國有304百萬磅的多氯聯(lián)苯被當(dāng)做電流體使用,大約150000阿斯卡列〔不易燃的電流體變壓器。About70000PCBtrans-formersareinornearcommercialbuildingsthatareopentothepublic.大約70000多氯聯(lián)苯變壓器建在或靠近對公眾開放的商業(yè)建筑。About40000ofthesetransformersareownedbyelectricalutilities.Approximately15000ofthesetransformersareusedinthefoodandfeedindustry.大約40000這些變壓器缺少電設(shè)施。大約15000這些變壓器被使用在食品和飼料工業(yè)。Utilitiesandotherindustriesmustmaintainordisposeofapproximately150000askarel-typetransformersthatmaydevelopleaks.公用事業(yè)等行業(yè)必須保持或處置約150000氯代聯(lián)苯-型變壓器可能出現(xiàn)的漏洞。Eachyear,anestimated317askarel-typetrans-formerscanbeexpectedtoleak.Eachwillloseabout5.3galor66lbofPCBs.公共設(shè)施和其他工業(yè)必須維護(hù)或處理大約150000阿斯卡列型變壓器可能產(chǎn)生的泄露,每一年,估計317阿斯卡列型變壓器被暴露泄露,將損失5.3㎡/s或66磅多氯聯(lián)苯。Transformersclassification變壓器的分類TheEPAhasthreeclassificationfortransformers:環(huán)保局已對變壓器三分類：PCBtransformerscontain500ormoreppmPCBs.多氯聯(lián)苯變壓器,多氯聯(lián)苯含量在百萬分之500或超過百萬分之一。Theymustbeinspectedquarterlyforleaks,anddetailedrecordsmustbekept.每季度被檢查出的泄露會被詳細(xì)的記錄并保存。Nomaintenanceworkinvolvingremovalofthecoreisallowed.除去核心沒有維持工作涉及的是被允許的。Attheendofthetransformers'usefullife,itmustbedestroyedinanEPA-approvedfacility,orthetransformerliquidmustbeincineratedandthecarcasslandfilled.在變壓器有效壽命的盡頭,它會被環(huán)境保護(hù)局支持的設(shè)施銷毀,或變壓器的液體被焚燒和外殼被掩埋。ThecourtsandtheEPAhaveheldtheoriginaltransformerownerliableforleakagethatmayoccurforaslongasthecarcassremainsinthelandfill.環(huán)境保護(hù)局要呼吁變最初壓器擁有者對液體泄漏負(fù)責(zé)任并且提供足夠大的場地對變壓器掩埋。PCB-contaminatedtransformerscontainbetween50and400ppmPCBsandrequirean-nualinspection.Theruleconcerningdisposal,maintenance,andrecordkeepingarelessre-strictiveandlesscostlythanthoseforPCBtransformers.受多氯聯(lián)苯污染的變壓器,多氯聯(lián)苯含量在百萬分之50至百萬分之400之間和要求必須每年檢查。管理涉及處理、維護(hù)、記錄保持在最小限制或者接近多氯聯(lián)苯變壓器要求的含量。Non-PCBtransformershavelessthan50ppmPCBsandareexemptfromtheburden-somerulesandrequirementsthatapplytoPCBandPCBscontaminatedtransformers.沒有多氯聯(lián)苯的變壓器,多氯聯(lián)苯含量少于百萬分之50和免除了一些繁雜的規(guī)則和要求比在應(yīng)用于多氯聯(lián)苯變壓器和受多氯聯(lián)苯污染的變壓器。Non-PCBtransformersaregrantedfavorundertheToxicSubstancesControlAct.沒有多氯聯(lián)苯的變壓器被包含在美國有毒物質(zhì)控制法里。AnalysisofPCBs多氯聯(lián)苯分析Analyticalmethodsmostfrequentlyusedfordetectingchlorinatedbiphenylsarecapillarycol-umngaschromatographycoupledwithmassspectrometryintheMID<MultipleIonDetec-tion>modeandcapillarycolumngaschromatographywithECD<ElectronCaptureDetec-tor>.分析法最頻繁用于發(fā)現(xiàn)含氯聯(lián)苯,在多離子檢測的模式下頂空毛管氣象色譜與質(zhì)譜分析結(jié)合、頂空毛管氣象色譜與電子捕獲測器結(jié)合。HPLC<HighPressureLiquidChromatography>andinfraredspectroscopyareapplica-bletoalimitedextent.高效液相色譜和紅外光譜適用于限制的范圍。SummaryPCBdeterminationsarealsopossible,thoughnotusual.Theserequireexhaustivechlorinationandmeasurementofthedecachlorbiphenycontentordechlorinationandsubsequentbiphenylmeasurement.總結(jié),多氯聯(lián)苯的測定盡管不常用,也是有可能的。這是需要徹底的氯化作用好十氯聯(lián)苯內(nèi)容的測定或者脫氯后聯(lián)苯的測定。InfraredtestedonPCBs多氯聯(lián)苯的紅外測試InfraredthermaltreatmenttechnologywasfieldtestedforeffectivenessonPCBscontamina-tedsoilattwoSuperfundsitesduring1986.在1986年期間,紅外熱治療技術(shù)在倆個超級基金地被現(xiàn)場檢測受多氯聯(lián)苯污染的土地的有效性。Thetransportablepilotsystemconsistedofaprimaryfurnacethroughwhichsolid/semisolidwasteswereconveyedonawiremeshbelt.移動式試驗系是由一個一次火爐通過固體/半固體廢物被傳送到鋼絲網(wǎng)運(yùn)輸帶。Theheatsourcewassuppliedbyelectricglowbarsinlieuofgaseousfuels.火源通過發(fā)電光棒代替氣體燃料提供。Residencetimesandfurnacetemperaturescouldbecontrolledmanuallyorautomaticallygivinguniformash.為了提供均化灰分,停留時間和燃燒爐溫度可以手動或自動控制。Asecondarychamber,heatedbyelectricorgaseousfuels,followedtheprimaryfurnaceandprovidedtemperaturesmexcessof220°F.ThesystemwasdesignedtocomplywithallRCRAandTSCArequirements.二次火爐通過電或氣體燃料加熱,與一次火爐一樣和提供的溫度超過2200F。系統(tǒng)被設(shè)計成符合資源保護(hù)和回收法案以及美國有毒物質(zhì)控制法要求。Selectfrom"PaulN.C.,Highhazardouspollutants,Asestos,PCBs,dioxins,biomedicalwastes,PollutionEngineering,Vol.21,No.2,1989"unit12Text:WaterPollutionandPollutants第十二單元：水污染與污染物Therelationshipbetweenpollutedwateranddiseasewasfirmlyestablishedwiththecholeraepidemicof1854inLondo,England.Protectionofpublichealth,theoriginalpurposeofpollutioncontrol,continuestobetheprimaryobjectiveinmanyareas.1854年英國倫敦爆發(fā)了大規(guī)模的流行性霍亂。此事明確地證實了污水和疾病之間的關(guān)系。當(dāng)初以公共健康為目的所采取的污染控制,依然是許多地區(qū)的主要目的。However,preserva-tionofwaterresources,protectionoffishingareas,andmaintenanceofrecreationalwatersareadditionalconcernstoday.然而,水資源的保持,產(chǎn)魚區(qū)的防護(hù),以及娛樂活動用水的維持在今天也成為關(guān)注的焦點。WaterpollutionproblemsintensifiedfollowingWorldWarIIwhendramaticincreasesinurbandensityandindustrializationoccurred.緊隨第二次世界大戰(zhàn)之后所產(chǎn)生的城市人口密度突增和工業(yè)化進(jìn)程的加劇,都使得水污染問題越見明顯。Concernoverwaterpollutionreachedapeakinthemid-seventies.致使對于水污染的關(guān)注程度在70年代中期達(dá)到了頂峰。Waterpollutionisanimprecisetermthatrevealsnothingabouteitherthetypeofpollu-tingmaterialoritssource.Thewaywedealwiththewasteproblemdependsuponwhetherthecontaminantsareoxygendemanding,algaepromoting,infectious,toxic,orsimplyun-sightly.水污染是一個不準(zhǔn)確的術(shù)語,它并未指出污染物的種類和來源。而我們處理廢水問題的方式往往取決于以下幾個方面：污染物是否需要氧氣,是否助長藻類,是否有傳染性,是否有毒,或者僅僅是否好看。Pollutionofourwaterresourcescanoccurdirectlyfromseweroutfallsorindustrialdischarges<pointsources>orindirectlyfromairpollutionoragriculturalorurbanrunoff<nonpointsources>.水源的污染可能直接來自生活污水的排放或工廠污水排放〔點源,也可能間接地由空氣污染、農(nóng)業(yè)排水或城市排水〔非點源所引發(fā)。Chemicallypurewater1sacollectionofH20molecules--nothingelse.化學(xué)上所謂的純水僅僅是水分子的集合。Suchasub-stanceisnotfoundinnature--notinwildstreamsorlakes,notincloudsorrain,notinfallingsnow,norinthepolaricecaps.無論在野外的河流或湖泊、云層或雨水中,還是在下雪期間,極地的冰帽地區(qū),這種物質(zhì)在自然界均不能找到。Verypurewatercanbepreparedinthelaboratorybutonlywithconsiderabledifficulty.然而在實驗室中可以制備非常純凈的水,但是存在一定的困難。Wateracceptsandholdsforeignmatter.因為水極易接受和容納外來物質(zhì)。Municipalwastewater,alsocalledsewage,isacomplexmixturecontammgwater<usuallyover99percent>togetherwithorganicandinorganiccontaminants,bothsuspen-dedanddissolved.城市污水,也被稱作生活污水,是一種復(fù)雜的混合物,它包含水〔通常超過99％以及懸浮或溶解的有機(jī)和無機(jī)污染物。Theconcentrationofthesecontaminantsisnormallyverylowandisex-pressedinmg/L,thatis,milligramsofcontaminantperliterofthemixture.這些污染物的濃度通常很低并且以mg/L來表示,也就說,每升混合物含有多少毫克污染物。Thisisaweight-to-volumeratiousedtoindicateconcentrationsofconstituentsinwater,wastewater,industrialwastes,andotherdilutesolutions.重量與體積比也常用來表示在水、廢水、工業(yè)廢水和其它稀釋溶液中的污染物濃度。Microorganisms.Whereverthereissuitablefood,sufficientmoisture,andanappropri-atetemperature,microorganismswillthrive.微生物任何地方只要存在適合的食物,充足的濕度和適當(dāng)?shù)臏囟?微生物即可大量繁殖。Sewageprovidesanidealenvironmentforavastarrayofmicrobes,primarilybacteria,plussomevirusesandprotozoa.而生活污水為各種各樣的微生物提供了一個理想的環(huán)境。這些微生物主要是細(xì)菌,某些病毒和原生動物。Mostofthesemicroorganismsinwastewaterareharmlessandcanbeemployedinbiologicalprocessestoconvertorganicmattertostableendproducts.廢水中的大多數(shù)微生物是無害的,并且可借助生化過程,將有機(jī)物轉(zhuǎn)化為穩(wěn)定的最終產(chǎn)物。However,sewagemayalsocontainpathogensfromtheexcretaofpeoplewithinfectiousdiseasesthatcanbetransmittedbycontaminatedwater.但是當(dāng)一些人患有可通過有毒廢水傳播的傳染性疾病時,其排泄物所攜帶的致病病原體,極有可能成為污水的組成部分。Waterbornebacterialdiseasessuchascholera,typhoid,andtuberculosis,viraldis-easessuchasinfectioushepatitis,andtheprotozoan-causeddysentery,whileseldomaprob-lemnowindevelopedcountries,arestillathreatwhereproperlytreatedwaterisnotavai-lableforpublicuse.雖然在發(fā)達(dá)國家,類似于水傳播的細(xì)菌性疾病,例如霍亂、傷寒和肺結(jié)核,病毒性疾病例如傳染性的肝炎和原生蟲引起的痢疾,已經(jīng)不再是問題,但是在那些經(jīng)過適當(dāng)處理過的污水不能被公共利用的地區(qū)仍然存在著很大威脅。Testsforthefewpathogensthatmightbepresentaredifficultandtimecon-suming,andstandardpracticeistotestforothermoreplentifulorganismsthatarealwayspres-ent<inthebillions>intheintestinesofwarm-bloodedanimals,includinghumans.對于少量存在的病原體的檢測是相當(dāng)困難和耗時的。其標(biāo)準(zhǔn)做法是檢測存在于包括人類在內(nèi)的〔數(shù)十億熱血動物腸胃中的有機(jī)物。Solids.固體Thetotalsolids<organicplusinorganic>inwastewaterare,bydefinition,theres-iduesaftertheliquidportionhasbeenevaporatedandtheremainderdriedtoaconstantweightat103℃.廢水中的總固體〔包括有機(jī)的和無機(jī)的是指液體部分被蒸發(fā),并且在103℃烘干至恒重的殘余物。Differentiationbetweendissolvedsolidsandundissolved,thatis,suspended,solidsareaccomplishedbyevaporatingfilteredandunfilteredwastewatersamples.區(qū)分可溶性固體和懸浮固體的方法,是通過蒸發(fā)過濾的和沒有通過過濾的廢水樣品來進(jìn)行的。Thedifferenceinweightbetweenthetwodriedsamplesindicatesthesuspendedsolidscontent.兩種烘干樣品質(zhì)量的差值即表示懸浮物的質(zhì)量。Tofurthercategorizetheresidues,theyareheldat550"Cfor15minutes.Theashremainingisconsideredtorepresentinorganicsolidsandthelossofvolatilemattertobeameasureoftheorganiccontent.將殘留物在550℃溫度下保持15分鐘以進(jìn)一步分類,剩余的灰代表了無機(jī)物,失去的揮發(fā)物則代表有機(jī)物的重量。Suspendedsolids<SS>andvolatilesuspendedsolids<VSS>arethemostuseful.懸浮固體〔SS和揮發(fā)性的懸浮固體〔VSS是最有用的。SSandBOD<biochemicaloxygendemand>areusedasmeasuresofwastewaterstrengthandprocessperformance.SS和BOD〔生化需氧量是廢水的受污染程度及其過程性能的指標(biāo)。VSScanbeanindicatoroftheorganiccontentofrawwastesandcanal-soprovideamea:mreoftheactivemicrobialpopulationinbiologicalprocesses.VSS可以指示廢水中有機(jī)物的含量,也可以衡量在生化過程里活性的微生物群。Inorganicconstituents.Thecommoninorganicconstituentsofwastewaterinclude:無機(jī)成分廢水中常見的無機(jī)成分包括：1. Chloridesandsulphates.Normallypresentinwaterandinwastesfromhumans.1．氯化物和硫酸鹽。常見于人類排放的廢水和廢物中。2. Nitrogenandphosphorous<D.Intheirvariousforms<organicandinorganic>inwastesfromhumans,withadditionalphosphorousfromdetergents.2．氮和磷。以各種形式〔有機(jī)的和無機(jī)的存在于來自人類排放的廢物,和含磷的清潔劑。3.Carbonatesandbicarbonates?.Normallypresentinwaterandwastesascalciumandmagnesiumsalts.3．碳酸鹽和碳酸氫鹽。通常以鈣鹽和鎂鹽的形式出現(xiàn)在水和廢物中。4.Toxicsubstances.Arsenic,cyanide,andheavymetalssuchasCd,Cr,Cu,Hg,Pb,andZnaretoxicinorganicswhichmaybefoundinindustrialwastes.4．有毒物質(zhì)。砷,氰化物和在工業(yè)廢水中可以找到的有毒無機(jī)物：Cd〔鎘、Cr〔鉻、Hg〔汞、Pb〔鉛、Zn〔鋅等重金屬。Inadditiontothesechemicalconstituents,theconcentrationofdissolvedgases,especiallyoxygen,andthehydrogenionconcentrationexpressedaspHareotherparametersofinter-estinwastewater.除了這些化學(xué)成分,溶解氣體的濃度,尤其是氧氣,用pH值所表示的H離子的濃度也是其它引起廢水注意的指標(biāo)。Organicmatter.有機(jī)物Proteinsandcarbohydrates?constitute90percentoftheorganicmatterindomesticsewage.生活污水中的有機(jī)物90％是由蛋白質(zhì)和碳水化合物組成。Thesourcesofthesebiodegradablecontaminantsincludeexcretaandurinefromhumans;foodwastesformsinks;soilanddirtfrombathing;washing,andlaun-dering;plusvarioussoaps,detergents,andothercleaningproducts.這些可生物降解的物質(zhì)包括人類的尿和排泄物、洗滌槽的食物殘渣、土和洗澡的臟物、洗衣用水和洗燙水,及各種肥皂、洗潔精和其他清潔產(chǎn)品。Variousparametersareusedasameasureoftheorganicstrengthofwastewater.各種指標(biāo)用來衡量廢水中有機(jī)物濃度。Onemethodisbasedontheamountoforganiccarbon<totalorganiccarbon,orTOC?>presentinthewaste.一種方法是基于廢水中的有機(jī)碳的總量〔即總有機(jī)碳TOC。TOCisdeterminedbymeasuringtheamountofC02producedwhentheorganiccarboninthesampleisoxidizedbyastrongoxidizerandcomparingitwiththeamountinastandardofknownTOC.總有機(jī)碳是由樣品中有機(jī)碳被強(qiáng)氧化劑氧化成二氧化碳的數(shù)量與已知的總有機(jī)碳的標(biāo)準(zhǔn)數(shù)量的比較所決定的。Mostoftheothercommonmethodsarebasedontheamountofoxygenrequiredtocon-verttheoxidizablematerialtostableendproducts.常見的另一種方法是根據(jù)把氧化物轉(zhuǎn)化成穩(wěn)定的最終產(chǎn)物所需要的氧氣。Sincetheoxygenusedisproportionaltotheoxidizablematerialpresent,itservesasarelativemeasureofwastewaterstrength.ThetwomethodsusedmostfrequentlytodeterminetheoxygenrequirementsofwastewateraretheCOD?andBOD?tests.因為需氧量正比于污水中現(xiàn)存的氧化物,它可以用于廢水濃度的相對衡量。通常確定廢水需氧量的兩種方法是COD〔化學(xué)需氧量和BOD〔生化需氧量的測定。TheCOD,orchemicaloxygendemand,ofthewastewateristhemeasuredamountofoxygenneededtochemicallyoxidizetheorganicspresent;theBOD,orbiochemicaloxygendemand,isthemeasuredamountofoxygenrequiredbyacclimatedmi-croorganismstobiologicallydegradetheorganicmatterinthewastewater.化學(xué)需氧量,是用化學(xué)方法氧化有機(jī)物的需氧量。而生化需氧量,是通過適應(yīng)環(huán)境的微生物的以生物的方式降解廢水中的有機(jī)物的需氧量。BODisthemostimportantparameterinwaterpollutioncontrol.Itisusedasameasureoforganicpollution,asabasisforestimatingtheoxygenneededforbiologicalprocesses,andasanindicatorofprocessperformance.在水污染控制理論中,生化需氧量是最重要的參數(shù)。生化需氧量用于測定有機(jī)物污染,是評估生物反應(yīng)需氧量的基礎(chǔ)和反應(yīng)過程的指標(biāo)。Theamountoforganicmatterinwaterorwastewatercanbemeasureddirectly<asTOC,forexample>,butthisdoesn'ttelluswhethertheorganicsarebiodegradableornot.我們可以直接地測定水或者廢水中的有機(jī)物含量〔例如測定總有機(jī)碳,但是這并不能告訴我們有機(jī)物是否有被生物降解。TomeasuretheamountofbiodegradableorganicsCD,weuseanindirectmethodinwhichwemeasuretheamountofoxygenusedbyagrowingmicrobialpopulationtoconvert<oxi-dize>organicmattertoC02andH20inaclosedsystem.為了測定可生物降解的有機(jī)物量,我們用一種間接的方法,也就是在一個封閉的系統(tǒng)里,測定將有機(jī)物轉(zhuǎn)化〔氧化成二氧化碳和水所用的生長的微生物群的耗氧量。Theoxygenconsumed,orbio-chemicaloxygendemand<BOD>,isproportionaltotheorganicmatterconverted,耗用的氧氣,或生化需氧量,正比于有機(jī)物的轉(zhuǎn)化量,andthereforeBODisarelativemeasureofthebiologicallydegradableorganicmatterpresentinthesystem.因此,生化需氧量是系統(tǒng)中生物降解有機(jī)物的相對衡量。Becausebiologicaloxidationcontinuesindefinitely,thetestforultimateBODhasbeenarbitrarilylimitedto20days,whenperhaps95percentormoreoftheoxygenrequire-menthasbeenmet.因為生物氧化過程可以無限次地進(jìn)行,最終生化需氧量的測定被限定為20天,這個時間能夠滿足95%或以上的微生物氧氣需求。Eventhisperiod,however,istoolongtomakemeasurementofBODuseful,但是過程時間過長,致使生化需氧量的測定沒有效用,soafive-daytest,BODs?,carriedoutat20°C,hasbecomestandard.所以一種五天式的測定,即將水樣置于20℃的黑暗環(huán)境五天,作為生化需氧量的標(biāo)準(zhǔn)。TherateoftheBODreactiondependsonthetypeofwastepresentandthetemperatureandisassumedtovarydirectlywiththeamountoforganicmatter<organiccarbon>present.生化需氧量的反應(yīng)速度取決于存在的廢水類型、溫度以及假設(shè)其隨著存在的有機(jī)物〔有機(jī)碳的數(shù)量的變化趨勢。Unit14Text:WaterPurificationWatermoleculeshavenomemory,andthereforehissillytotalkaboutthenumberoftimesthatthewateryoudrinkhasbeenpollutedandrepurified,asifthemoleculesgraduallyworeout.水分子是沒有記憶力的,所以談?wù)摫晃廴竞捅粌艋娘嬘盟拇螖?shù)是沒意義的,例如分子的逐漸損耗。Allthatisimportantishowpureitiswhenyoudrinkit.而當(dāng)我們飲水的時候到底它有多純凈才是最重要的。Thepurificationofwaterhasdevelopedintoanelaborateandsophisticatedtechnology.水的凈化已經(jīng)發(fā)展為一項復(fù)雜的和尖端的技術(shù)。However,thegeneralapproachestopurificationshouldbecomprehensible,andinsomeca-sesevenobvious,fromageneralunderstandingofthenatureofwaterpollution.然而,污水凈化的本質(zhì)的總方法是容易理解的,在某些情況下也是明顯的。Impuritiesinwaterwereclassifiedassuspended,colloidal,ordissolved.里面的雜質(zhì)分類為懸浮的,膠體的,或者是溶解的。Suspendedparticlesarelargeenoughtosettleoutortobefiltered.水懸浮的顆粒物是大得足夠沉降下來或者可以被過濾掉的。Colloidalanddissolvedimpuritiesaremoredifficulttoremove.膠體的顆粒物和溶解的顆粒物是更難除去。Onepossibilityissomehowtomakethesesmallparticlesjointo-gethertobecomelargerones,whichcanthenbetreatedassuspendedmatter.一是可以用某些方法使小的顆粒物結(jié)合起來變成大的顆粒物,然后把大的顆粒物作為懸浮物來進(jìn)行處理。Anotherpossi-bilityistoconvertthemtoagasthatescapesfromthewaterintotheatmosphere.Whatevertheapproach,itmustberememberedthatenergyisrequiredtoliftwaterortopumpitthroughafilter<D.二是可以把它們轉(zhuǎn)換為氣體,從水中排放到大氣中。不論采取哪一種方法,必須記住,提升水或用泵將水輸送到通過過濾床都需要能量。Withtheseprinciplesmmind,considertheproceduresusedinpurifyingmunicipalwastewaters.以上面原則作為依據(jù),來考慮用來凈化城市廢水的程度。Thefirststepisthecollectionsystem.第一步是收集系統(tǒng)。Waterbornewastesfromsourcessuchashomes,hospitals,andschoolscontainfoodresidues,humanexcrement,paper,soap,de-tergents,dirt,cloth,othermiscellaneousdebris,and,ofcourse,microorganisms.Thismixtureiscalledsanitaryordomesticsewage.水中的廢物有各種各樣的來源,例如家庭的,醫(yī)院的,學(xué)校的含有食品的殘余物,人類的排泄物,紙,肥皂,清潔劑,臟物,布,其他各種各樣的雜物,當(dāng)然還有微生物。這種混合物就叫做生活污水。<Theadjective"sanitary"isratherinappropri-atebecauseithardlydescribestheconditionofthesewage;itpr_esumablyreferstothatofthepremiseswhosewasteshavebeencarriedaway>.〔"生活污水"這個形容詞是很不合適的,因為它沒有描述污水的情況；它可能是指那些廢物排放出來的地方。Thesewaters,whicharesometimesjoinedbywastesfromcommercialbuildings,byindustrialwastes,andbytherunofffromrain,flowthroughanetworkofsewerpipes.這些污水有時跟商業(yè)建筑廢水,工業(yè)廢水和雨水混合在一起,一同流進(jìn)廢水的管路網(wǎng)絡(luò)里面去。Somesystemsseparatesewagefromrainwater,oth-erscombinethem.某些系統(tǒng)將雨水和生活污水分開,另一些系統(tǒng)又將兩者結(jié)合起來。Thecombinedpipingischeaperandisadequateindryweather,butdur-ingastormthetotalvolumeisapttoexceedthecapacityofthetreatmentplant,sosome1sallowedtooverflowandpassdirectlyintothereceivingstreamorriver.結(jié)合的網(wǎng)絡(luò)式是比較便宜的,而且適合干燥的天氣,但在暴雨時,總的體積很容易超過污水處理廠的容量,所以某些水就允許溢流出去和直接排放到河流里面去。PrimaryTreatment?初級處理Whenthesewagereachesthetreatmentplant,itfirstpassesthroughaseriesofscreensthatremovelargeobjectssuchasratsorgrapefruits,andthenthroughagrindingmechanismthatreducesanyremainingobjectstoasizesmallenoughtobehandledeffectivelyduringtheremainingtreatmentperiod.當(dāng)生活污水到達(dá)污水處理廠時,它首先通過一系列的濾網(wǎng)以除去如老鼠,葡萄柚似的大物體,和在接下來的處理時期里,通過一架磨碾機(jī)以減少剩下的物體的尺寸使其足夠小能有效地被處理。Thenextstageisaseriesofsettlingchambersdesignedtore-movefirsttheheavygrit,suchassandthatrainwaterbringsinfromroadsurfaces,andthen,moreslowly,anyothersuspendedsolids-includingorganicnutrientsthatcansettleoutinanhourorso.下一步是設(shè)置一系列的沉淀池以除去初始的粗沙,例如雨水從路面帶進(jìn)的沙子,然后,慢慢地任何其它的懸浮固體—包括在一個小時能沉淀下來的有機(jī)營養(yǎng)物。Uptothispointtheentireprocess,whichiscalledprimarytreatment,hasbeenrelativelyinexpensivebuthasnotaccomplishedmuch.直到這個階段,稱為初級處理,相對地便宜但并未完成凈化的程度。SecondaryTreatment?二級處理Thenextseriesofstepsisdesignedtoreducegreatlythedissolvedorfinelysuspendedorgan-icmatterbysomeformofacceleratedbiologicalaction.接下來的一系列步驟,是設(shè)計通過加速生化作用的某種形式來較大程度地減少溶解的或微小的懸浮有機(jī)物。Whatisneededforsuchdecomposi-tionisoxygenandorganismsandanenvironmentinwhichbothhavereadyaccesstothenu-trients.分解需要氧氣和微生物以及一種兩者都易接近營養(yǎng)物的環(huán)境。Onedeviceforaccomplishingthis'objectiveisthetricklingfilter?.達(dá)到這個目標(biāo)的一種裝置是滴濾池。Inthisdevice,longpipesrotateslowlyoverabedofstones,distributingthepollutedwaterincontinuoussprays.Asthewatertricklesoverandaroundthestones,itoffersitsnutrientsinthepres-enceofairtoanabundanceofratherunappetizingformsoflife.這種裝置,長管在由巖石填充而成的濾床上緩慢的旋轉(zhuǎn),通過持續(xù)地噴灑來分布這些污水。Analternativetechniqueistheactivatedsludgeprocess.另一個技術(shù)是活性污泥過程。Herethesewage,afterprimarytreatment,ispumpedintoanaerationtank,whereitismixedforseveralhourswithairandbacteria-ladensludge.廢水,經(jīng)過初級處理后,泵到一個混合空氣和含有細(xì)菌的污泥幾個小時的曝氣池。Thebiologicalactionissimilartothatwhichoccursinthetricklingfil-ter.Thesludgebacteriametabolizetheorganicnutrients;theprotozoa,assecondarycon-sumers,feedonthebacteria.生化作用與發(fā)生在滴濾池的相似。污泥中的細(xì)菌代謝轉(zhuǎn)化成有機(jī)氧物；原生蟲,作為二級消費(fèi)者,吃掉細(xì)菌。Thetreatedwatersthenflowtoasedimentationtank,wherethebacteria-ladensolidssettleoutandarereturnedtotheaerator.處理過的水流到一個含有細(xì)菌的固體沉降的沉淀池去,然后返回到曝氣池。Someofthesludgemustberemovedtomaintainsteady-stateconditions.某些污泥必須被排放以維持一個穩(wěn)定的狀態(tài)。Theactivatedsludgeprocessrequireslesslandspacethanthetricklingfilters,and,sinceitexposeslessareatotheatmosphere,itdoesnotstinksomuch.相對滴濾池來說,活性污泥需要占地少的面積,因為它需要曝氣較小的面積,沒有發(fā)出臭味。Theeffluentfromthebiologicalactionisstillladenwithbacteriaandisnotfitfordis-chargeintoopenwaters,letalonefordrinking.生化處理所排放的廢水仍然含有細(xì)菌,和不適合排放到清潔的水源,更不用說飲用。Sincethemicroorganismshavedonetheirwork,theymaynowbekilled.因為微生物完成其工作,現(xiàn)在就可以殺死他們了。Thefinalstepisthereforeadisinfectionprocess,usuallychlorination.最后一步是消毒過程,一般是加氯。Chlorinegas,氯氣,injectedintotheeffluent15to30minutesbeforeitsfinaldis-charge,cankillmorethan99percentoftheharmfulbacteria.在最后排放前加入到排水15至30分鐘,就可以殺滅99%以上的有害細(xì)菌。Tertiaryor"Advanced"Treatments?三級或高級處理Althoughconsiderablepurificationisaccomplishedbythetimewastewatershavepassedthroughtheprimaryandsecondarystages,thesetreatmentsarestillinadequatetodealwithsomecomplexaspectsofwaterpollution.盡管此時的廢水已經(jīng)通過初級和二級處理,得到了相當(dāng)大程度的凈化,但是這些處理仍然不合適應(yīng)對某些水污染的復(fù)雜方面。First,manypollutantsinsanitarysewagearenotremoved.Inorganicions,suchasnitratesandphosphates,remaininthetreatedwaters;thesematerials,aswehaveseen,serveasplantnutrientsandarethereforeagentsofeu-trophication.首先,生活污水里面有很多污染物是不能清除的。無機(jī)的離子,例如硝酸鹽和磷酸鹽,仍然在處理過的水中;這些物質(zhì),正如我們所看到的,可以作為植物的營養(yǎng)物和水體的營養(yǎng)成分。Thetreatmentmethodsavailabletocopewiththesetroublesomewastesarenecessarilyspecifictothetypeofpollutanttoberemoved,andtheyaregenerallyexpensive.Afewofthesetechniquesaredescribedbelow.用于應(yīng)付這些麻煩廢水的處理方式是必需專門除去這類污染物,而且它們一般很昂貴。如下描述幾種這些技術(shù)。1.CoagulationandSedimentation1． 混凝和沉淀Asmentionedearlierinthediscussionofbiologicaltreatment,itisadvantageoustochangelittleparticlesintobigonesthatsettlefaster.正如在生物處理的討論中我們早前提及的,將小的顆粒物轉(zhuǎn)變成的大的能夠快速沉淀的顆粒物是很有好處的。Soitisalsowithinorganicpollutants.所以它跟無機(jī)污染物同樣道理。Variousinorganiccolloidalparticlesarewaterloving<hydrophilic>andthereforeratheradhesive;intheirstickinesstheysweeptogethermanyothercolloidalparticlesthatwouldotherwisefailtosettleoutinareasonabletime.各種各樣的無機(jī)膠體顆粒是喜歡水的〔親水的并且具有相當(dāng)?shù)恼掣叫?；由于它們的粘附性它們一起帶走很多其他難以在合理時間內(nèi)沉降下來的膠體顆粒物。Thisprocessiscalledflocculation.Lime,alum,andsomesaltsofironareamongtheseso-calledflocculatingagents.這個過程被稱為絮凝。石灰,礬和某些鐵鹽都是這些所謂的絮凝劑。2.Adsorption2． 吸附Adsorptionistheprocessbywhichmoleculesofagasorliquidadheretothesurfaceofasol-id.吸附是氣體分子或液體分子粘附到固體表面的過程。Theprocessisselective-differentkindsofmoleculesadheredifferentlytoanygivensol-id.Topurifywater,asolidthathasalargesurfaceareaandbindspreferentiallytoorganicpollutantsisneeded.這個過程是具有選擇性的—不同種類的分子以不同的方式粘附在任何固體。對于凈化水,那些有著大的表面積并且結(jié)合傾向于有機(jī)污染物的固體是必需的。Thematerialofchoiceisactivatedcarbon,whichisparticularlyeffec-tiveinremovingchemicalsthatproduceoffensivetastesandodors.Theseincludethebiologi-callyresistantchlorinatedhydrocarbons.選擇的物質(zhì)是活性碳,它能夠特別有效地除去產(chǎn)生令人討厭的味道和臭味的化學(xué)品。這些化學(xué)品包括那些難以生物降解的氯代烴。3.OtherOxidizingAgents3． 其他氧化劑Potassiumpermanganate<KMn04>andozone<03>havebeenusedtooxidizewaterbornewastesthatresistoxidationbyairinthepresenceofmicroorganisms.高錳酸鉀和臭氧用于氧化那些抵抗空氣中微生物的氧化的水中廢物。Ozonehastheimpor-tantadvantagethatitsonlybyproductisoxygen.臭氧有一個很重要的優(yōu)點就是它僅存的副產(chǎn)物是氧氣。4.ReverseOsmosis4． 反滲透Osmosisistheprocessbywhichwaterpassesthroughamembranethatisimpermeabletodissolvedions.滲透是一個水通過一種不透過溶解離子的膜的過程。Inthenormalcourseofosmosis,thesystemtendstowardanequilibriuminwhichtheconcentrationsonbothsidesofthemembraneareequal.在正常的過程中,系統(tǒng)傾向于一個平衡狀態(tài),在這個平衡狀態(tài)中膜的兩邊的濃度是相同的。Thismeansthatthewaterflowsfromthepuresidetotheconcentrated"polluted"side.Thisisjustwhatwedon'twant,becauseitincreasesthequantityofpollutedwater.這意味著水從純凈的一邊流到富集污染物的一邊。這并不是我們所希望的,因為這個過程增加了被污染的水的數(shù)量。However,ifexcesspressureisap-pliedontheconcentratedside,theprocesscanbereversed,andthepurewaterissqueezedthroughthemembraneandthusfreedofitsdissolvedionicorothersolublepollutants.然而,假如高壓是加到富集污染物的一邊,這個過程可被逆轉(zhuǎn),純凈水就被擠壓通過這個膜,并且這樣就除去了溶解的離子或者其他溶解的污染物。Selectedfrom"]onathanTurk,AmosTurk.EnvironmentalScience,ThirdEdition,SaundersCollegePublishing,TheDrylenPress,USA,1984"ReadingMaterial:PrinciplesofWastewaterTreatmentEffluentRequirements流出物要求Theprimaryob