生物膜法处理有机废气 英语.docx

生物膜法处理有机废气 英语.docx

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生物膜法处理有机废气英语

Biofilmtreatmentoforganicwaste

LiRuixueCaiShenjianShenCheng

Abstract:

Hazardorganicwastehasbecometheconsensus,treatmentoforganicwastepollutionisoneofthekeyenvironmentalwork.Thispaperdescribesthesourcesoforganicwasteandhazards,describestheprinciplesofbiofilmtreatmentoforganicwaste,advantagesanddisadvantages,discusseditsresearchstatusanddevelopmenttrends.

Keyword:

Biofilm;Organicwaste;Treatment

1:

Preface

Boiofilmorganicgasmainlycomesfromthepetroleum,thechemicalindustryintheproductionprocessemissions.Ithasthecharacteristicthattheorganicmattercontentofupsanddowns,withcombustible,haveacertaintoxicityandtherewillbesomeodor.Chlorofluorocarbonemissionswillcausethedestructionoftheozonelayer.Petrochemicalproductionprocessandstorageequipment,printingandotherrelatedtopetroleumandchemicalindustry,theuseoforganicsolvents.,Petroleumproductsforavarietyoftransportationfuelsallabovethesewillcauseorganicgas.【1】

Themaincomponentsoforganicwasteareformaldehyde,acetone,aceticacid,ethyl-ester,additiveandotherorganicgasescontainingcarbonandoxygenandsoon.

Organicgasdamageplantleaftissueanddestroytheozonelayer,Fortheharmtohumanbodyisreflectedinmanyaspects.Benzeneishighlytoxicsolvents,evensmallamountscancauselong-termdamagetothehumanbody,itcanaccumulateinthebonemarrowandthenervoussystem,damagehematopoietictissueandnervoussystem,causeneurologicaldisorders,reducetheamountofwhitebloodcellsintheblood,platelet,worseissufferingfromleukemia.PAHandorganiccompoundshavestrongcarcinogenesis.Benzoicacidcanmaketheproteininacelldeformationorsolidification,thesystemicpoisoning.Nitrilescancausebreathingdifficulties,cancausesuffocationseriously,lossofconsciousnessuntildeath.Glycolethersolventinthehumanbodycanbeformedafterthemetabolismoftoxic,causepermanentdamagetothecirculatoryandnervoussystemofthebody.Femalereproductivesystemwouldalsobeaffected,seriouscanleadtoinfertility.Organicphosphoruscompoundscanreducebloodcholinesteraseactivity,resultinginnervoussystemdisorders.Aboutorganicsulfurcompounds,lowconcentrationofthiolcancausephysicaldiscomfort,butdeathathighconcentration.Toluenediisocyanatewithlowvaporpressure,haveastrongstimulatingeffectonthehumancornea,causingeyeirritation.Steamintothehumanbody,willdamagethefunctionofhumanliver,kidney,long-termexposuretotoluenediisocyanatesteamhighconcentrationsofcarcinogenic.

Therearetwomaintypestotreatorganicwastegas:

oneisrecovery.Therecoverymethodisphysicalmethod,weusetheadsorbentandselectivelypermeablemembranetoseparatevolatileorganiccompoundsinacertaintemperatureandpressureincludingactivecarbonadsorption,condensationmethod,Pressureswingadsorptionmethodandbiofilm..Anotheriseliminatetheseorganicwasteweturnorganicmatterintocarbondioxideandwaterusingoflight,heat,catalystandmicrobes,likelightdecompositionmethod,thethermaloxidationmethod,catalyticcombustionmethod,biologicaloxidation,coronamethod,plasmadecompositionandsoon.【2】

2:

Biofilmtreatmentoforganicwaste

2.1Mechanismofbiofilmtreatmentoforganicwaste

MechanismofbiofilmtreatmentoforganicwastewasfirstputforwardbyOttengraffromNetherlands.Thebiofilmtheorybiochemicalmethodoforganicwastegaspurificationprocessintothreesteps:

（1）First,theorganicpollutantsintheexhaustgasoncontactwithwateranddissolvedinwater.Thatis,bydiffusionintothefilmbytheFilm.

（2）Dissolvedintheliquidfilmoftheconcentrationdifferencebetweentheuseoforganicpollutantsingredientsspreadtothebiofilm,andwasoneofthemicroorganismstocaptureandabsorb.

（3）Microorganismsintoorganiccontaminantsinmicrobialmetabolicprocessesastheirenergyandnutrientsarebrokendownbybiochemicalreactionsandeventuallyconvertedintoharmlesscarbondioxideandwater.

Later,SunPeiShi,whonotedthatsomedonotdissolveinwaterorwater-solubleorganicmatter,difficulttousefilmdiffusionmethodtoexplain.Sotheyproposedadsorption-BiofilmTheory.Andbasedonthetreatmentoflowconcentrationsoftoluenegasexperimentstoestablishadynamicmodel.【3】Highlightsofthetheoryis:

（1）Organicpollutantsintheexhaustgasreachesthemembranebydiffusionandadsorptiontothemoistbiofilmsurface.

（2）Organicmatteriscapturedandabsorbedbymicrobes.

（3）Microbialdecomposescontaminantsandfinallyturnintocarbondioxideandwater.

2.2Advantagesofbiofilmtreatmentoforganicwaste

（1）Biodiversity:

Bothaerobicandanaerobicbacteria

（2）Biofilmlowmoisturecontent,alargebiomassperunitvolumemakeithaslargerprocessingcapacity.

（3）Processismorestable,lessconsumption,highremovalefficiency.

2.3Thedevelopmentoforganicwastegastreatment

Atpresent,processingtechnologyoforganicwastegasgeneraldevelopmentintotwocategories:

decompositioneliminationandconcentrationandrecovery.Decompositionisusedasthelight,electricity,eliminatingheat,plasmaandmicroorganismsoftheorganiccompoundsintocarbondioxideandwater.Concentrationandrecoveryisbyadsorption,absorption,condensationandmembraneseparation,theorganicmatterconcentrationrecycling.

Decompositionofeliminatingtreatmentwithoutrecyclingoforganicwastegasvalue,itstechnologyincludingdirectcombustion,catalyticcombustionmethod,coronamethod,plasmamethodandbiologicalmethod.Concentrationandrecoveryfortreatmentofhighconcentrationorganicwasteandrecyclingvalue,itstechnologyabsorptionmethod,adsorption,condensationandmembraneseparationmethod.

Organicwastegastreatmentnorecyclingvalue,suchasodorgasbycatalyticcombustionmethod,althoughthecleaningisthorough,butthecostisrelativelyhigh,butalsotheexistenceoftwopollution;corona,plasmatechnologyhasabetterapplicationprospect,buttherearestillsomedistancefromthepracticalaspects;biologicalmethodofsavingenergy,lowoperationcost,rarelyformedtwopollution,treatmentoflowconcentrationorganicwastegas（<3g/m-3）effectisbetter,inEuropeandtheUnitedStates,Japanandothernationshavebeenputintoindustrialoperation.Thetreatmentoforganicwastegasbyusingbiologicalmethodalthoughlate,buttheprospect,becauseofthelowconcentrationorganicindustrialwastegastreatmentandlackofeconomicalandeffectivemeasures,biologicalmethodcanplayarolein[4]isveryimportant.

Biologicalmethodsmainlyincludebiologicalfiltration,biologicalwashingmethodandbiologicaltricklingfilterprocessofthreetypes,includingbiologicalfiltrationandbiologicaltricklingthroughsurfacemembranebiologicalfillerinmicrobialtreatmentoforganicwastegas,sothesetwokindsofmethodsareknowncollectivelyasthebiologicalmembranemethod[5].

2.4Themainprocessform

Therearetwoformstotreatorganicgas：

Biofiltration，Biotricklingfiltration

（1）Biofiltration.Process:

organicwaste-humidifier-biofilter-purgegasemissions.Themaindeviceisahumidifierandbiofilter.Organicwastegetswetfirstinahumidifier,andthenintothebiofilter，Fillerlayerinthefilterisattachedwiththebiofilm,Liquidsubstantiallystaysstationaryorslow-speedflow.Moisture,pH,nutrientcanbesuppledifitisneeded.Mustensuregasgoesthroughfiltercontinuously.Thefillercanbesoil,plasticfilter,ceramicfilter,granularactivatedcarbon,peat,compost,etc.Thicknessisabout1m,theareaisdesignedbythegasflowandtheeffectoftreatment.

（2）Biotricklingfiltration.Vaporflow:

organicwaste-Biologicalfiltrationtowerbottom-purgegasemissions.LiquidFlow:

Circulatingfluid-Biologicalfiltrationtowerbottom-Circulatingliquidtank-Biologicalfiltrationtowerbottom（cycle）.Instructure,biologicalfiltrationtowerbottomissimilartobiofilterbutwhatdifferentisbiologicaltricklingfilterthecirculatingfluidsprayingfromthetopdown,theflowthroughtheinsideofthefillerlayer.Organicwastefromthebottomtoenter,afterpassingthroughthepackinglayeroutthroughthetoprow.Becausebiologicaltricklingfilterporeslargerthanpackingbiofilter,sothesmallertheresistanceofthegasthroughthebed.Sincetheliquidflowiseasytocontrolthereactionconditions（suchaspH,nutrientconcentrations,etc.）.Biologicaltricklingfiltertreatmentofhighloadoforganicwasteisstrongerthantheeffectofbiologicalfiltration.

3：

Majordesignandcraftparameters

3.1Filter

Biofilmfillerchosenshouldmeetthefollowingcriteria:

（1）Bettersurfacepropertiesofthefiller,suitableforthegrowthofmicroorganisms;

（2）Thelargesurfaceareaoffiller;

（3）Therearecertainstructuralstrengthandcorrosionresistance;

（4）Hasahighporosityandlowbulkdensity;

（5）Easiertoobtainandlonglife.

Therearetwomainfilters:

naturalfillersandartificialfillers.Naturalfillersincludesoil,compost,peatsubstancecontainingnutrientsingeneral;Artificialfillerlikeactivatedcarbon,diatomaceousearth,coke,polystyreneandpolyurethanefoambeadsneedanadditionaladding,becauseitdoesnotcontainnutritiousmatter.Somenewlydevelopedfillersuchasactivatedcarbonfibersandadheredtotheporoushydrophobicpolypropylenefilm.Further,addingactivatedcarbon,coke,etc.Intheconventionalfiller,thefillercanimprovetheperformanceandextendthelifeofuse.

Fillershouldbeusedtocontrolthehumidity,thehumidityistoolow,willmakemicrobialinactivation,fillersshrinkagecracking,etc.,soitisnecess