aspectwisediskcleaner

Received:17September,2008.
Accepted:29September,2009.
InvitedReviewDynamicBiochemistry,ProcessBiotechnologyandMolecularBiology2010GlobalScienceBooksEnvironmentalBiotechnology:Achievements,OpportunitiesandChallengesMariaGavrilescu*"GheorgheAsachi"TechnicalUniversityofIasi,FacultyofChemicalEngineeringandEnvironmentalProtection,DepartmentofEnvironmentalEngineeringandManagement,71MangeronBlvd.
,700050Iasi,RomaniaCorrespondence:*mgav@ch.
tuiasi.
roABSTRACTThispaperdescribesthestate-of-the-artandpossibilitiesofenvironmentalbiotechnologyandreviewsitsvariousareastogetherwiththeirrelatedissuesandimplications.
Consideringthenumberofproblemsthatdefineandconcretizethefieldofenvironmentalbiotechnology,theroleofsomebioprocessesandbiosystemsforenvironmentalprotection,controlandhealthbasedontheutilizationoflivingorganismsareanalyzed.
Environmentalremediation,pollutionprevention,detectionandmonitoringareevaluatedconsideringtheachievements,aswellastheperspectivesinthedevelopmentofbiotechnology.
Variousrelevanttopicshavebeenchosentoillustrateeachofthemainareasofenvironmentalbiotechnology:wastewatertreatment,soiltreatment,solidwastetreatment,andwastegastreatment,dealingwithboththemicrobiologicalandprocessengineeringaspects.
Thedistinctroleofenvironmentalbiotechnologyinthefutureisemphasizedconsideringtheopportunitiestocontributewithnewsolutionsanddirectionsinremediationofcontaminatedenvironments,minimizingfuturewastereleaseandcreatingpollutionpreventionalternatives.
Totakeadvantageoftheseopportunities,innovativenewstrategies,whichadvancetheuseofmolecularbiologicalmethodsandgeneticengineeringtechnology,areexamined.
Thesemethodswouldimprovetheunderstandingofexistingbiologicalprocessesinordertoincreasetheirefficiency,productivity,andflexibility.
Examplesofthedevelopmentandimplementationofsuchstrategiesareincluded.
Also,thecontributionofenvironmentalbiotechnologytotheprogressofamoresustainablesocietyisrevealed.
Keywords:biologicaltreatment,bioremediation,contaminatedsoil,environmentalbiotechnology,heavymetal,naturalattenuation,organiccompound,phytoremediation,recalcitrantorganic,remediationAbbreviations:BOD5,five-daybiologicaloxygendemand;CNT,carbonnanotube;MBR,membranebioreactor;MSAS,membraneseparationactivatedsludgeprocess;MTBE,methyltert-butylether;TCE,trichloroethylene;VOC,volatileorganiccompoundsCONTENTSINTRODUCTION.
1ROLEOFBIOTECHNOLOGYINDEVELOPMENTANDSUSTAINABILITY.
2ENVIRONMENTALBIOTECHNOLOGY-ISSUESANDIMPLICATIONS.
3ENVIRONMENTALREMEDIATIONBYBIOTREATMENT/BIOREMEDIATION4Microbesandplantsinenvironmentalremediation.
6Factorsaffectingbioremediation7Wastewaterbiotreatment10Soilbioremediation16Solidwastebiotreatment17Biotreatmentofgaseousstreams18Biodegradationofhydrocarbons.
19Biosorption.
19Biodegradationofrefractorypollutantsandwaste20ENVIRONMENTALBIOTECHNOLOGYINPOLLUTIONDETECTIONANDMONITORING.
22Bioindicators/biomarkers.
22Biosensorsforenvironmentalmonitoring23ENVIRONMENTALBIOTECHNOLOGYFORPOLLUTIONPREVENTIONANDCLEANERPRODUCTION24Roleofbiotechnologyinintegratedenvironmentalprotectionapproach24Processmodificationandproductinnovation.
25ENVIRONMENTALBIOTECHNOLOGYANDECO-EFFICIENCY.
29CONCLUDINGREMARKS-ENVIRONMENTALBIOTECHNOLOGYCHALLENGESANDPERSPECTIVES30ACKNOWLEDGEMENTS30REFERENCES.
30INTRODUCTIONBiotechnology"istheintegrationofnaturalsciencesandengineeringinordertoachievetheapplicationoforganisms,cells,partsthereofandmolecularanaloguesforproductsandservices"(vanBeuzekomandArundel2006).
Biotech-nologyisversatileandhasbeenassessedakeyareawhichhasgreatlyimpactedvarioustechnologiesbasedontheapplicationofbiologicalprocessesinmanufacturing,agri-culture,foodprocessing,medicine,environmentalprotec-DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBookstion,resourceconservation(Fig.
1)(ChistiandMoo-Young1999;EC2002;EvansandFurlong2003;Gavrilescu2004a;GavrilescuandChisti2005).
Thisnewwaveoftech-nologicalchangeshasdetermineddramaticimprovementsinvarioussectors(productionofdrugs,vitamins,steroids,interferon,productsoffermentationusedasfoodordrink,energyfromrenewableresourcesandwaste,aswellasgeneticengineeringappliedonplants,animals,humans)sinceitcanprovideentirelynovelopportunitiesforsus-tainableproductionofexistingandnewproductsandser-vices(Johnston2003;Das2005;GavrilescuandChisti2005).
Inaddition,environmentalconcernshelpdrivetheuseofbiotechnologynotonlyforpollutioncontrol(decon-taminationofwater,air,soil),butpreventpollutionandminimizewasteinthefirstplace,aswellasforenviron-mentallyfriendlyproductionofchemicals,biomonitoring.
ROLEOFBIOTECHNOLOGYINDEVELOPMENTANDSUSTAINABILITYTheresponsibleuseofbiotechnologytogeteconomic,soci-alandenvironmentalbenefitsisinherentlyattractiveanddeterminesaspectacularevolutionofresearchfromtradi-tionalfermentationtechnologies(cheese,bread,beermaking,animalandplantbreeding),tomoderntechniques(genetechnology,recombinantDNAtechnologies,biochemistry,immunology,molecularandcellularbiology)toprovideefficientsynthesisoflowtoxicityproducts,renewablebio-energyandyieldingnewmethodsforenvironmentalmoni-toring.
Thestartofthe21stcenturyhasfoundbiotechnologyemergingasakeyenablingtechnologyforsustainableenvi-ronmentalprotectionandstewardship(Cantor2000;Gavri-lescu2004b;Arai2006).
Therequirementforalternativechemicals,feedstocksforfuels,andavarietyofcommercialproductshasgrowndramaticallyintheearlyyearsofthe21stCentury,drivenbythehighpriceofpetroleum,policiestopromotealternativesandreducedependenceonforeignoil,andincreasingeffortstoreducenetemissionsofcarbondioxideandothergreenhousegases(Hettenhaus2006).
Thesocial,environmentalandeconomicbenefitsofenviron-mentalbiotechnologygohand-in-handtocontributetothedevelopmentofamoresustainablesociety,aprinciplewhichwaspromotedintheBrundtlandReportin1987,inAgenda21oftheEarthSummitinRiodeJaneiroin1992,theReportoftheWorldSummitonSustainableDevelop-mentheldinJohannesburgin2002andwhichhasbeenwidelyacceptedintheenvironmentalpolicies(EIBE2000;OECD2001).
Regardingthesedomainsofapplication,fourmainsub-fieldsofbiotechnologyareusuallytalkedabout:-greenbiotechnology,theoldestuseofbiotechnologybyhumans,dealswithplantsandgrowing;-redbiotechnology,appliedtocreatechemicalcom-poundsformedicaluseortohelpthebodyinfightingdiseasesorillnesses;-whitebiotechnology(oftengreenbiotech),focusingonusingbiologicalorganismstoproduceormanipulateproductsinabeneficialwayfortheindustry;-bluebiotechnology–aquaticuseofbiologicaltech-nology.
Themainactionareasforbiotechnologyasimportantinresearchanddevelopmentactivitiescanbeseenasfallingintothreemaincategories(Kryl2001;Johnston2003;GavrilescuandChisti2005):-industrialsupplies(biochemicals,enzymesandrea-gentsforindustrialandfoodprocessing);-energy(fuelsfromrenewableresources);-environment(pollutiondiagnostics,productsforpol-lutionprevention,bioremediation).
Thesearesuccessfullyassistedbyvariousdisciplines,suchasbiochemicalbioprocessesandbiotechnologyengi-neering,geneticengineering,proteinengineering,metabolicengineering,requiredforcommercialproductionofbiotech-nologyproductsanddeliveryofitsservices(OECD1994;EFB1995;OECD1998;EvansandFurlong2003;Gavri-lescuandChisti2005).
Thisreviewfocusesontheachievementsofbiotechno-logicalapplicationsforenvironmentalprotectionandcon-trolandfutureprospectsandnewdevelopmentsinthefield,consideringtheopportunitiesofenvironmentalbiotechno-logytocontributewithnewsolutionsanddirectionsinremediationandmonitoringofcontaminatedenvironments,minimizingfuturewastereleaseandcreatingpollutionpre-ventionalternatives.
BIOTECHNOLOGYENVIRONMENTALBIOTECHNOLOGYDecontaminationofenvironmentalcomponents(water,air,soil)ProductionofchemicalsBiosensorsPollutionpreventionandwasteminimizationFOODTECHNOLOGYProductsoffermentation(wine,beer,cheese,yoghurt,yeastsetc.
)AGRICULTUREEnergyfromrenewableresources,agriculturalwasteGENETICTECHNOLOGYGeneticengineeringappliedonplantsandanimalsGeneticengineeringappliedonhumansMEDICINEProductionofantibiotics,vitamins,steroids,insulin,interferonFig.
1Applicationofbiotechnologyinanthropogenicactivities(industry,agriculture,medicine,health,environment).
(AdaptedfromSukumaranNair2006).
2Environmentalbiotechnology.
MariaGavrilescuENVIRONMENTALBIOTECHNOLOGY-ISSUESANDIMPLICATIONSAsarecognitionofthestrategicvalueofbiotechnology,in-tegratedplansareformulatingandimplementinginmanycountriesforusingbiotechnologyforindustrialregenera-tion,jobcreationandsocialprogress(Rijaux1977;Gavri-lescuandChisti2005).
Withtheimplementationoflegislationforenvironmen-talprotectioninanumberofcountriestogetherwithsettingofstandardsforindustryandenforcementsofcompliance,environmentalbiotechnologygainedinimportanceandbroadnessinthe1980s.
Environmentalbiotechnologyisconcernedwiththeap-plicationofbiotechnologyasanemergingtechnologyinthecontextofenvironmentalprotection,sincerapidindustriali-zation,urbanizationandotherdevelopmentshaveresultedinathreatenedcleanenvironmentanddepletednaturalresources.
Itisnotanewareaofinterest,becausesomeoftheissuesofconcernarefamiliarexamplesof"old"techno-logies,suchas:composting,wastewatertreatmentetc.
Initsearlystage,environmentalbiotechnologyhasevolvedfromchemicalengineering,butlater,otherdisciplines(bioche-mistry,environmentalengineering,environmentalmicro-biology,molecularbiology,ecology)alsocontributetoen-vironmentalbiotechnologydevelopment(HasimandUjang2004).
Thedevelopmentofmultiplehumanactivities(inindus-try,transport,agriculture,domesticspace),theincreaseinthestandardoflivingandhigherconsumerdemandhaveamplifiedpollutionofair(withCO2,NOxSO2,greenhousegasses,particulatematters),water(withchemicalandbio-logicalpollutants,nutrients,leachate,oilspills),soil(duetothedisposalofhazardouswaste,spreadingofpesticides),theuseofdisposablegoodsornon-biodegradablematerials,andthelackofproperfacilitiesforwaste(Fig.
2).
Studiesandresearchesdemonstratedthatsomeofthesepollutantscanbereadilydegradedorremovedthankstobiotechnologicalsolutions,whichinvolvetheactionofmic-robes,plants,animalsundercertainconditionsthatenvisageabioticandbioticfactors,leadingtonon-aggressivepro-ductsthroughcompoundsmineralization,transformationorimmobilization(Fig.
3).
Advancedtechniquesortechnologiesarenowpossibletotreatwasteanddegradepollutantsassistedbylivingorg-anismsortodevelopproductsandprocessesthatgeneratelesswasteandpreservethenaturalnon-renewableresourcesandenergyasaresultof(Olguin1999;EIBE2000;Gavri-lescuandChisti2005;Chisti2007):-improvedtreatmentsforsolidwasteandwastewater;-bioremediation:cleaningupcontaminationandphytoremediation;-ensuringthehealthoftheenvironmentthroughbio-monitoring;-cleanerproduction:manufacturingwithlesspollutionorlessrawmaterials;-energyfrombiomass;-geneticengineeringforenvironmentalprotectionandcontrol.
Unfortunately,someenvironmentalcontaminantsarerefractorywithacertaindegreeoftoxicityandcanaccumu-lateintheenvironment.
Furthermore,thetreatmentofsomepollutantsbyconventionalmethods,suchaschemicaldeg-radation,incinerationorlandfilling,cangenerateothercon-taminants,whichsuperimposedonthelargevarietyofnoxi-ouswastepresentintheenvironmentanddetermineincrea-singconsiderationtobeplacedonthedevelopmentofcom-binationwithalternative,economicalandreliablebiologicaltreatments(OECD1994;EFB1995;Krieg1998;OECD1998;Futrell2000;EvansandFurlong2003;Kuhnetal.
2003;Chenetal.
2005;Gavrilescu2005;BetianuandGavrilescu2006a,2006b).
Atleastfourkeypointsareconsideredforenvironmen-talbiotechnologyinterventionstodetect(usingbiosensorsINDUSTRYTRANSPORTAGRICULTUREDOMESTICParticulatepollutantsNOX,SO2,CO2OthergreenhousegasesChemicalandbiologicalpollutantsLeakagefromdomesticwastetipsEutrophicationcausedbynitrogenandphosphoroussourcesOilspillsHazardouswasteOilspillsPersistentorganicpollutantsIncreaseinsoilactivityduetomassivespreadingAIRSOILWATERFig.
2Thespiderofenvironmentalpollutionduetoanthropogenicactivities.
(AdaptedfromEIBE2000).
3DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksandbiomonitoring),preventinthemanufacturingprocess(bysubstitutionoftraditionalprocesses,singleprocessstepsandproductswiththeuseofmodernbio-andgenetechnologyinvariousindustries:food,pharmaceutical,tex-tiles,productionofdiagnosticproductsandtextiles),controlandremediatetheemissionofpollutantsintotheenviron-ment(Fig.
4)(bydegradationofharmfulsubstancesduringwater/wastewatertreatment,soildecontamination,treat-mentandmanagementofsolidwaste)(Olguin1999;Chenetal.
2005;Das2005;Gavrilescu2005;GavrilescuandNicu2005).
Othersignificantareaswhereenvironmentalbiotechnologycancontributetopollutionreductionarepro-ductionofbiomolecules(proteins,fats,carbohydrates,lipids,vitamins,aminoacids),yieldimprovementinoriginalplantproducts.
Theproductionprocessesthemselvescanassistinthereductionofwasteandminimizationofpol-lutionwithintheso-calledcleantechnologiesbasedonbio-technologicalissuesinvolvedinreuseorrecyclewastestreams,generateenergysources,orproducenew,viableproducts(EvansandFurlong2003;GavrilescuandChisti2005;Gavrilescuetal.
2008).
Byconsideringalltheseissues,biotechnologymayberegardedasadrivingforceforintegratedenvironmentalprotectionbyenvironmentalbioremediation,wasteminimi-zation,environmentalbiomonitoring,biomaintenance.
ENVIRONMENTALREMEDIATIONBYBIOTREATMENT/BIOREMEDIATIONEnvironmentalhazardsandrisksthatoccurasaresultofaccumulatedtoxicchemicalsorotherwasteandpollutantscouldbereducedoreliminatedthroughtheapplicationofbiotechnologyintheformof(bio)treatment/(bio)remedia-tinghistoricpollutionaswellasaddressingpollutionresul-tingfromcurrentindustrialpracticesthroughpollutionpre-ventionandcontrolpractices.
BioremediationisdefinedbyUSEnvironmentalProtectionAgency(USEPA)as"aman-agedorspontaneouspracticeinwhichmicrobiologicalpro-cessesareusedtodegradeortransformcontaminantstolesstoxicornontoxicforms,therebyremediatingoreliminatingenvironmentalcontamination"(USEPA1994;Talley2005).
Biotreatment/bioremediationmethodsarealmosttypical"end-of-pipeprocesses"appliedtoremove,degrade,ordetoxifypollutioninenvironmentalmedia,includingwater,air,soil,andsolidwaste.
Fourprocessescanbeconsideredasactingonthecontaminant(Asante-Duah1996;FRTR1999;Khanetal.
2004;DobleandKumar2005;Gavrilescu2006):1.
removal:aprocessthatphysicallyremovestheconta-minantorcontaminatedmediumfromthesitewithouttheneedforseparationfromthehostmedium;2.
separation:aprocessthatremovesthecontaminantfromthehostmedium(soilorwater);3.
destruction/degradation:aprocessthatchemicallyorbiologicallydestroysorneutralizesthecontaminanttoproducelesstoxiccompounds;4.
containment/immobilization:aprocessthatimpedesorimmobilizesthesurfaceandsubsurfacemigrationofthecontaminant;Removal,separation,anddestructionareprocessesthatreducetheconcentrationorremovethecontaminant.
Con-tainment,ontheotherhand,controlsthemigrationofacon-taminanttosensitivereceptorswithoutreducingorre-movingthecontaminant(Watson1999;Khanetal.
2004;Gavrilescu2006).
Removalofanypollutantfromtheenvironmentcantakeplaceonfollowingtworoutes:degradationandim-mobilizationbyaprocesswhichcausesittobebiologicallyunavailablefordegradationandsoiseffectivelyremoved(EvansandFurlong2003).
Asummaryofprocessesin-volvedinbioremediationasagenericprocessispresentedinFig.
5(Gavrilescu2004).
Immobilizationcanbecarriedoutbychemicalsreleasedbyorganismsoraddedintheadjoiningenvironment,whichcatchorchelatethecontaminant,makingitinsoluble,thusunavailableintheenvironmentasanentity.
Sometimes,immobilizationcanbeamajorprobleminremediationbecauseitcanleadtoagedcontaminationandalotofre-searcheffortneedstobeappliedtofindmethodstoturnovertheprocess.
Destruction(biodegradationandbiotransformation)iscarriedoutbyanorganismoracombinationoforganisms(consortia)andisthecoreofenvironmentalbiotechnology,sinceitformsthemajorpartofappliedprocessesforenvi-ronmentalcleanup.
BiotransformationprocessesusenaturalMineralsFossilfuelsXenobioticsAbioticfactors(temperature,pH,redoxpotential)Bioticfactors(toxicity,specificity,activity)MicrobesPlantsAnimalsMineralizationTransformationImmobilizationFig.
3Sourcesofenvironmentalpollutantsandfactorsthatinfluencetheirremovalfromtheenvironment.
(AdaptedfromChenetal2005).
EnvironmentalbiotechnologyManufacturingprocessPollutionprevention/cleanerproductionWastemanagementPollutioncontrolFig.
4Keyinterventionpointsofenvironmentalbiotechnology.
4Environmentalbiotechnology.
MariaGavrilescuandrecombinantmicroorganisms(yeasts,fungi,bacteria),enzymes,wholecells.
Biotransformationplaysakeyroleintheareaoffoodstuff,pharmaceuticalindustry,vitamins,specialtychemicals,animalfeedstock(Fig.
6)(TrejoandQuintero1999;Dobleetal.
2004;SinghalandShrivastava2004;Chenetal.
2005;DaleandKim2006;Willkeetal.
2006).
Metabolicpathwaysoperatewithinthecellsorbyenzymeseitherprovidedbythecelloraddedtothesystemaftertheyareisolatedandoftenimmobilized.
Biologicalprocessesrelyonusefulmicrobialreactionsincludingdegradationanddetoxificationofhazardousorga-nics,inorganicnutrients,metaltransformations,appliedtogaseous,aqueousandsolidwaste(Eglit2002;EvansandFurlong2003;Gavrilescu2004a).
Acompletebiodegradationresultsindetoxificationbymineralizingpollutantstocarbondioxide,waterandharm-BioremediationDefinition:completemineralizationofcontaminantsthroughbiologicalactivityRequirements:microorganisms,plants,substrate(food)andnutrients(nitrogen,phosphorous,potassium),electronacceptors(aerobic:O2;anaerobic:nitrate,sulphate,etc.
)Advantages-mosthydrocarbonsandorganiccompoundswillbemineralized-intrinsicmicrobes(thosealreadyfoundinthesoil)willmostlybeabletoacclimatizetothecontaminants-insteadoftransferringcontaminantsfromoneenvironmentalmediumtoanother,thecompletedestructionoftargetpollutantsispossible-itusuallydoesnotproducetoxicby-products-isusuallylessexpensivethanothertechnologies-itcanbeusedwheretheproblemislocated,oftenwithoutcausingamajordisruptionofnormalactivitiesLimitations-islimitedtothosecompoundsthatarebiodegradable-shortsupplyofsubstrate,electronacceptors,ornutrientswillhinderbioactivity-highlevelsoforganiccontaminantsmaybetoxictothemicrobes-heavymetalsmayinhibitthemicrobialactivity-thecontaminantmustbeprovidedinanaqueousenvironment-thelowerthetemperature,theslowerthedegradation-theprocessmustbecarefullymonitoredtoensuretheeffectiveness-itisdifficulttoextrapolatefrombenchandpilot-scalestudiestofull-scalefieldoperations-oftentakeslongerthanotheractionsMethodsofmicrobialbioremediationinsitu:type:biosparging,bioventing,bioaugumentation,insitubiodegradationbenefits:mostcostefficient,noninvasive,relativelypassive,naturalattenuationprocess,treatssoilandwaterlimitations:environmentalconstraints,extendedtreatmenttime,monitoringdifficultiesfactorstoconsider:biodegradativeabilitiesofindigenousmicroorganisms,presenceofmetalsandotherinorganics,environmentalparameters,biodegradabilityofpollutants,chemicalsolubility,geologicalfactors,distributionofpollutantsex-situ:type:landfarming,composting,biopilesbenefits:costefficient,lowcost,canbedoneonsitelimitations:spacerequirements,extendedtreatmenttime,needtocontrolabioticloss,masstransferproblem,bioavailabilitylimitationsbioreactors:type:slurryreactors,aqueousreactorsbenefits:rapiddegradationkinetic,optimizedenvironmentalparameters,enhancedmasstransfer,effectiveuseofinoculantsandsurfactantslimitations:soilrequiresexcavation,relativelyhighcostcapital,relativelyhighoperatingcostsfactorstoconsider:bioaugumentation,toxicityofamendaments,toxicconcentrationofcontaminantsMicroorganismsandprocessesAerobic:-(requiressufficientoxygen:Pseudomonas,Alcaligenes,Sphingomonas,Rhodococcus,Mycobacterium)-degradepesticidesandhydrocarbons,bothalkanesandpolyaromaticcompounds-bacteriausethecontaminantasthesolesourceofcarbonandenergy-nogenerationofmethane-itisafasterprocessAnaerobic:-(intheabsenceofoxygen,thustheenergyinputisslow)-anaerobicbacteriaarenotasfrequentlyusedasaerobicbacteria-anaerobicbacteriaareusedforbioremediationofpolychlorinatedbiphenyls(PCBs)inriversediments,dechlorinationofthesolventtrichloroethylene(TCE),chloroform-itmaygeneratemethaneLigninolyticfungi:-havetheabilitytodegradeanextremelydiverserangeofpersistentortoxicenvironmentalpollutants(aswhiterotfungusPhanaerochaetechrysosporium)-commonsubstratesusedincludestraw,sawdust,orcorncobsMethylotrophs-growutilizingmethaneforcarbonandenergy-areactiveagainstawiderangeofcompounds,includingthechlorinatedaliphaticstrichloroethyleneand1,2-dichloroethaneMethodsofphytoremediationPhytoextractionorphytoaccumulation-theplantsaccumulatecontaminantsintotherootsandabovegroundshootsorleaves-savestremendousremediationcostbyaccumulatinglowlevelsofcontaminantsfromawidespreadarea-producesamassofplantsandcontaminants(usuallymetals)thatcanbetransportedfordisposalorrecyclingPhytotransformationorphytodegradation-uptakeoforganiccontaminantsfromsoil,sediments,orwaterand,subsequently,theirtransformationtomorestable,lesstoxic,orlessmobileformPhytostabilization-plantsreducethemobilityandmigrationofcontaminatedsoil-leachableconstituentsareadsorbedandboundintotheplantstructuresothattheyformastablemassofplantfromwhichthecontaminantswillnotreentertheenvironmentPhytodegradationorrhizodegradation-breakdownofcontaminantsthroughtheactivityexistingintherhizosphere,duetothepresenceofproteinsandenzymesproducedbytheplantsorbysoilorganismssuchasbacteria,yeast,andfungi-isasymbioticrelationshipthathasevolvedbetweenplantsandmicrobes:plantsprovidenutrientsnecessaryforthemicrobestothrive,whilemicrobesprovideahealthiersoilenvironmentRhizofiltration-isawaterremediationtechniquethatinvolvestheuptakeofcontaminantsbyplantroots-isusedtoreducecontaminationinnaturalwetlandsandestuaryareaPhytovolatilization-plantsevaportranspirateselenium,mercury,andvolatilehydrocarbonsfromsoilsandgroundwaterVegetativecap-rainwaterfromsoilisevaportranspiratedbyplantstopreventleachingcontaminantsfromdisposalsitesFig.
5Characteristicsandparticularitiesofbioremediation.
(AdaptedfromVidali2001;Gavrilescu2004a).
5DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBookslessinorganicsalts.
Incompletebiodegradationwillyieldbreakdownpro-ductswhichmayormaynotbelesstoxicthantheoriginalpollutantandcombinedalternativeshavetobeconsidered,suchas:dispersion,dilution,biosorption,volatilizationand/orthechemicalorbiochemicalstabilizationofcontami-nants(Lloyd2002;Gavrilescu2004a).
Inaddition,bioaugmentationinvolvesthedeliberateadditionofmicroorganismsthathavebeencultured,adap-ted,andenhancedforspecificcontaminantsandconditionsatthesite.
Biorefiningentailstheuseofmicrobesinmineralpro-cessingsystems.
Itisanenvironmentallyfriendlyprocessand,insomecases,enablestherecoveryofmineralsanduseofresourcesthatotherwisewouldnotbepossible.
Currentresearchonbioleachingofoxideandsulfideoresaddressesthetreatmentofmanganese,nickel,cobalt,andpreciousmetalores(SuklaandPanchanadikar1993;Smithetal.
1994).
Fig.
7providessomebioprocessalternativesforheavymetalsremovalfromtheenvironment(Lloyd2002;Gavri-lescu2004a).
Biologicaltreatmentprocessesarecommonlyappliedtocontaminantsthatcanbeusedbyorganismsascarbonorenergysources,butalsoforsomerefractorypollutants,suchas:xorganics(petroleumproductsandothercarbon-basedchemicals);xmetals(arsenic,cadmium,chromium,copper,lead,mercury,nickel,zinc);xradioactivematerials.
MicrobesandplantsinenvironmentalremediationAllformsoflifecanbeconsideredashavingapotentialfunctioninenvironmentalbiotechnology.
However,mic-robesandcertainplantsareofinterestevenasnormallypresentintheirnaturalenvironmentorbydeliberateintro-duction(EvansandFurlong,2003).
Thegenericterm"microbe"includesprokaryotes(bac-teriaorarcaea)andeukariotes(yeasts,fungi,protozoa,andunicellularplants,rotifers).
BiotransformationFoodstuffAnimalfeedsuplementPharmaceuticals/vitaminsWastetreatmentSpecialtychemicals/chiraldrugintermediatesFig.
6Applicationsofbiotransformations.
MicrobialCellBiosorption2L-2L-2L-M2+M2+M2+Bioleachinge.
g.
HeterotrophicleachingInsolublemetalOrganicacid+SolublemetalchelateMetal(oxidizedsoluble)Metal(oxidizedinsoluble)2e-MO22+MO2HPO42-+M2+MHPO4BiomineralizationH2S+M2+MSEnzyme-catalysedtransformationse.
g.
BioreductionFig.
7Mechanismsofmetal-microbeinteractionsduringbioremediationapplications.
(Lloyd2002;Gavrilescu2004a).
6Environmentalbiotechnology.
MariaGavrilescuSomeoftheseorganismshavetheabilitytodegradesomeofthemosthazardousandrecalcitrantchemicals,sincetheyhavebeendiscoveredinunfriendlyenvironmentswheretheneedsforsurvivalaffecttheirstructureandmetaboliccapability.
Microorganismsmayliveasfreeindividualsorascom-munitiesinmixedcultures(consortia),whichareofparticu-larinterestinmanyrelevantenvironmentaltechnologies,likeactivatedsludgeorbiofilminwastewatertreatment(GavrilescuandMacoveanu1999;GavrilescuandMaco-veanu2000;MetcalfandEddy1999).
Oneofthemostsig-nificantkeyaspectsinthedesignofbiologicalwastewatertreatmentsystemsisthemicrobialcommunitystructuresinactivatedsludges,constitutedfromactivatedsludgeflocs,whichenclosevariousmicroorganismtypes(Fig.
8,Table1)(WagnerandAmann1997;Wagneretal.
2002).
Theroleofplantsinenvironmentalcleanupisexertedduringtheoxygenationofamicrobe-richenvironment,fil-tration,solid-to-gasconversionorextractionofcontami-nants.
Theuseoforganismsfortheremovalofcontaminationisbasedontheconceptthatallorganismscouldremovesubstancesfromtheenvironmentfortheirowngrowthandmetabolism(Hamer1997;Saval1999;Wagneretal.
2002;Dobleetal.
2004;Gavrilescu2004;Gavrilescu2005):-bacteriaandfungiareverygoodatdegradingcom-plexmolecules,andtheresultantwastesaregenerallysafe(fungicandigestcomplexorganiccompoundsthatarenormallynotdegradedbyotherorganisms);-protozoa-algaeandplantsprovedtobesuitabletoabsorbnitrogen,phosphorus,sulphur,andmanymineralsandmetalsfromtheenvironments.
Microorganismsusedinbioremediationincludeaerobic(whichusefreeoxygen)andanaerobic(whichliveonlyintheabsenceoffreeoxygen)(Fig.
5)(Timmisetal.
1994;Hamer1997;Cohen2001;Wagneretal.
2002;Gray2004;Brinzaetal.
2005a,2005b;Moharikaretal.
2005).
Somehavebeenisolated,selected,mutatedandgeneticallyengi-neeredforeffectivebioremediationcapabilities,includingtheabilitytodegraderecalcitrantpollutants,guaranteebet-tersurvivalandcolonizationandachieveenhancedratesofdegradationintargetpollutedniches(GavrilescuandChisti2005).
Theyarefunctionalinactivatedsludgeprocesses,lag-oonsandponds,wetlands,anaerobicwastewatertreatmentanddigestion,bioleaching,phytoremediation,land-farming,slurryreactors,tricklingfilters(Burtonetal.
2002;Mul-ligan2002).
Table1proposesashortsurveyofmicrobialgroupsinvolvedinenvironmentalremediation(Rigaux1997;Pandey2004;Wangetal.
2004;Bitton2005).
FactorsaffectingbioremediationTwogroupsoffactorscanbeidentifiedthatdeterminethesuccessofbioremediationprocesses(Saval1999;NazaroffandAlvarez-Cohen2001;Beaudetteetal.
2002;Wagneretal.
2002;SasikumarandPapinazath2003;Bitton2005;Gavrilescu2005):-natureandcharacterofcontaminant/contamination,whichreferstothechemicalnatureofcontaminantsandtheirphysicalstate(concentration,aggregationstate:solid,liquid,gaseous,environmentalcomponentthatcontainsit,oxido-reductionpotential,presenceofhalo-gens,bondstypeinthestructureetc.
);-environmentalconditions(temperature,pH,water/air/soilcharacteristics,presenceoftoxicorinhibitingsubstancestothemicroorganism,sourcesofenergy,sourcesofcarbon,nitrogen,tracecompounds,tempera-ture,pH,moisturecontent.
Also,bioremediationtendstorelyonthenaturalabili-tiesofmicroorganismstodeveloptheirmetabolismandtooptimizeenzymesactivity(Fig.
9).
Theprimecontrollingfactorsareair(oxygen)availabi-lity,moisturecontent,nutrientlevels,matrixpH,andam-bienttemperature(Table2)(Vidali2001).
Usually,forensuringthegreatestefficiency,theidealrangeoftemperatureis20-30°C,apHof6.
5-7.
5or5.
9-9.
0(dependentonthemicrobialspeciesinvolved).
Othercir-cumstances,suchasnutrientavailability,oxygenationandthepresenceofotherinhibitorycontaminantsareofgreatimportanceforbioremediationsuitability,foracertaintypeofcontaminatandenvironmentalcompartment,therequiredremediationtargetsandhowmuchtimeisavailable.
Theselectionofacertainremediationmethodentailsnon-engi-neeredsolutions(naturalattenuation/intrinsicremediation)oranengineeredone,basedonagoodinitialsurveyandriskassessment.
Anumberofinterconnectedfactorsaffectthischoice(asisalsoillustratedinFigs.
5,10):xcontaminantconcentrationxcontaminant/contaminationcharacteristicsandtypexscaleandextentofcontaminationxtherisklevelposedtohumanhealthorenvironmentxthepossibilitytobeappliedinsituorexsituxthesubsequentuseofthesitexavailableresourcesBioremediationtechnologiesofferanumberofadvan-tagesevenwhenbioremediationprocesseshavebeenestab-lishedforbothinsituandexsitutreatment(Fig.
10),suchas(EIBE2000;SasikumarandPapinazath2003;Gavrilescu2005;GavrilescuandChisti2005):-operationalcostsavingscomparativetoothertech-nologies-minimalsitedisturbance-lowcapitalcosts-destructionofpollutants,andnottransferringtheproblemelsewhere-exploitationofinteractionswithothertechnologiesTheseadvantagesarecounterbalancedbysomedis-NutrientsSewagebacteriaSludgebacteriaFlagellateprotozoaAttachedandcrawlingciliateprotozoaAttachedcarnivorousciliateprotozoaFreeswimmingciliateprotozoaFreeswimmingcarnivorousciliateprotozoaFig.
8Structureofmicrobialcommunityinactivatedsludge.
(AdaptedfromWagneretal.
2002;Bitton2005).
7DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksadvantages(Boopathy2000;SasikumarandPapinazath2003):-influenceofpollutantcharacteristicsandlocalcondi-tionsonprocessimplementation-viabilityneedstobeimproved(timeconsumingandexpensive)-communitydistressforsafetyoflarge-scaleon-sitetreatment-othertechnologiesshouldbenecessary-mayhavelongtime-scaleThebiotreatmentisappliedaboveallinwastewatertreatment,soilbioremediation,solidwastetreatment,bio-treatmentofgaseousstreams.
(Bio)treatmentofmunicipalwastewaterbyactivatedTable1Surveyofmicrobialgroupsinvolvedinenvironmentalremediation.
MicroorganismsTypeShapeExampleAbilitiesReferencescoccisphericalshapeStreptococcushydrocarbon-degradingbacteriaheavyoildegradedairyindustrywaste(whey)Atlas1981LeahyandColwell1990Ince1998Donkin1997Gradyetal.
1999Marques-Rochaetal.
2000BlonskayaandVaalu2006Kumaretal.
2007Mohanaetal.
2007Xuetal.
2009bacillirodsBacilliussubtilisdegradecrudeoilbioremediationofchlorpyrifos-contaminatedsoilGallertandWinter1999Eglit2002DasandMukherjee2007Lakshmietal.
2009spiralformsVibriocholeraSpirillumvolutansheavymetalsBitton2005sheatedbacteriafilamentous(gram-negativerodsthatbecomeflagellated)SphaeratilusLeptothrixCrenothrixreduceirontoferrichydroxide(Sphaeratilusnatans,Crenothrix)reducemanganesetomanganeseoxide(Leptothrix)foundinpollutedstreamsandwastewatertreatmentplantsSuklaandPanchanadikar1993Smithetal.
1994Sasakietal.
2001Gray2004Bitton2005Fitzgiblonetal.
2007Caulobacteraerobic,aquaticenvironmentswithloworganiccontentPoindexteretal.
2000Bitton2005ptalkedbacteriaflagellatedGallionellaG.
ferruginea,presentinironrichwatersandoxidizesFe2+toFe3+.
canbeformedinwaterdistributionsystemsBenzetal.
1998Blanco2000Smithetal.
2004Bitton2005Hyphomicrobiumsoilandaquaticenvironmentsrequiresone-carboncompoundstogrow(e.
g.
methanol)TrejoandQuintero1999GallertandWinter2001Burtonetal.
2002DuncanandHoran2003buddingbacteriafilamentsorhyphaeRhodomicrobiumphototrophicBitton2005glidingbacteriafilamentous(gram-negative)BeggiatoaThiothrixoxidizeH2StoS0Droste1997GuestandSmith2002Reddyetal.
2003bdellovibrioflagellated(predatory)B.
bacteriovorusgrowindependentlyoncomplexorganicmediaBitton2005Sarataleetal.
2009actinomycetesfilamentous(gram-positive)mycelialgrowthMicromonosporaStreptomycesNocordia(Gordonia)xmostarestrictaerobesxfoundinwater,wastewatertreatmentplants,soils(neutralandalkaline)xdegradepolysaccharides(starch,cellulose),hydrocarbons,ligninxcanproduceantibiotics(streptomycin,tetracycline,chloramphenicol)xGordoniaisasignificantconstituentoffoamsinactivatedsludgeunitsGradyetal.
1999Lemaetal.
1999Olguin1999Saval1999DuncanandHoran2003Gavrilescu2004Bitton2005Dashetal.
2008Joshietal.
2008Bacteriacyanobacteria(blue-greenalgae)unicellular,colonialorfilamentousorganismsAnabaenaxprokaryoticorganismsxabletofixnitrogenxhaveahighresistancetoextremeenvironmentalconditions(temperature,dessication)sothatarefoundindesertsoilandhotspringsxresponsibleforalgalbloomsinlakesandotheraquaticenvironmentsxsomearequitetoxicBlanco2000Burtonetal.
2002Bitton2005Brinzaetal.
2005aEl-Sheekhetal.
2009Archeacrenarchaeoteseuryarchaeoteskorarchaeotes(morecloselyrelatedtoeukaryotesthantobacteria)extremophylesthermophileshyperthermophilespsychrophilesacidophilesalkaliphileshalophilesxprokaryoticcellsxuseorganiccompoundsasasourceofcarbonandenergy(organotrophs)xuseCO2asacarbonsource(chemoautothrophs)Eglit2000Burtonetal.
2002Gavrilescu2002Dunnetal.
2003Bitton2005DobleandKumar20058Environmentalbiotechnology.
MariaGavrilescusludgemethodwasperhapsthefirstmajoruseofbiotech-nologyinbioremediationapplications.
Municipalsewagetreatmentplantsandfilterstotreatcontaminatedgasesweredevelopedaroundtheturnofthecentury.
Theyprovedveryeffectivealthoughatthetime,thecausefortheiractionwasunknown.
Similarly,aerobicstabilizationofsolidwastethroughcompostinghasalonghistoryofuse.
Inaddition,bioremediationwasmainlyusedincleanupoperations,in-cludingthedecompositionofspilloilorslagloadscon-tainingradioactivewaste.
Then,bioremediationwasfoundasthemethodofchoicewhensolvents,plasticsorheavymetalsandtoxicsubstanceslikeDDT,dioxinsorTNTneedtoberemoved(EIBE2000;BetianuandGavrilescu2006a).
Generaladvantagesassociatedwiththeuseofbiologi-Table1(Cont.
)MicroorganismsTypeShapeExampleAbilitiesReferenceslongfilaments(hiphae)whichformamasscalledmycelliumxuseorganiccompoundsascarbonsourceandenergy,andplayanimportantroleinnutrientrecyclinginaquaticandsoilenvironmentsxsomeformtrapsthatcaptureprotozoaandnematodesxgrowunderacidicconditionsinfoods,waterorwastewater(pH5)ximplicatedinseveralindustrialapplication(fermentationprocessesandantibioticproduction)Hamer1997Burtonetal.
2002BrinzaandGavrilescu2003Guptaetal.
2004Bitton2005Phycomycetes(watermolds)xoccuronthesurfaceofplantsandanimalsinaquaticenvironmentssomeareterrestrial(commonbreadmold,Rhizopus)DuncanandHoran2003Bitton2005Ascomycetes(Neurosporacrassa,Saccharomycescerevisiae)someyeastsareimportantindustrialmicroorganismsinvolvedinbread,wine,beermakingBitton2005fungiBasidiomycetes(mushrooms-Agaricus,Amanita(poisonous))wood-rottingfungiplayasignificantroleinthedecompositionofcelluloseandligninHernández-Lunaetal.
2007Bitton2005Fungiiimperfecti(ex.
Penicillium)cancauseplantdiseasesGadd2007floatingunicellularmicroorganismsphyloplanktonChavanandMukherji2010filamentousUhlothrixTuzenetal.
2009Volvoxxplaytheroleofprimaryproducersinaquaticenvironments(oxidationpondsforwastewatertreatment)xcarryoutoxygenicphotosynthesisandgrowinmineralmediawithvitaminsupplements(providebysomebacteria)andwithCO2asthecarbonsourcexsomeareheterotrophicanduseorganiccompounds(simplesugarsandorganicacids)assourceofcarbonandenergyDuncanandHoran2003FengandAldrich2004algaecolonialPhylumChlorophyta(greenalgae)PhylumChrysophyta(golden-brownalgae)PhylumEuglenophytaPhylumPyrrophyta(dinoflagellates)PhylumRhodophyta(redalgae)PhylumPhaeophyta(brownalgae)Bitton2005Gadd2007ProtozoaunicellularorganismsimportantforpublichealthandprocessmicrobiologyinwaterandwastewatertreatmentEukaryotesSarcodina(amoeba)Mastigophora(flagellates)Ciliophora(ciliates)Sporozoaxresistanttodesiccation,starvation,hightemperature,lackofoxygen,disinfectioninwatersandwastewatersxfoundinsoilsandaquaticenvironmentsxsomeareparasitictoanimalsandhumansBitton2005VirusesBelongneithertoprokaryotesnortoeukaryotes(carryoutnocatabolicoranabolicfunctions)AnimalvirusesAlgalvirusesBacterialphagesxsomeareindicatorsofcontaminationxdistructhostcellsxinfectawiderangeoforganisms(animals,algae,bacteria)DuncanandHoran20039DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBookscalprocessesforthetreatmentofhazardouswastesrefertotherelativelylowcosts,simpleandwell-knowntechnolo-gies,potentialforcompletecontaminantdestruction(Naza-roffandAlvarez-Cohen2001;SasikumarandPapinazath2003;Gavrilescu2005).
WastewaterbiotreatmentTheuseofmicroorganismstoremovecontaminantsfromwastewaterislargelydependentonwastewatersourceandcharacteristics.
EnvironmentTemperatureMoisturecontentpHElectronacceptorsNutrientsContaminantToxicityConcentrationAvailabilitySolubilitySorptionMicroorganismsMetabolicallycapableDegradingpopulationIndigenousGeneticallyengineeredbioremediationFig.
9Mainfactorsofinfluenceinbioremediationprocesses.
(AdaptedfromBeaudetteetal.
2002;Bitton2005).
InsitutechniquesExsitutechniquesTechnologytransitionrelativelyunrestrictedlessthanayearfreewidespreadlocalizedlowtomediummediumtohighdeepwithinsiterelativelynearsurfacetimecontaminationconcentrationdepthFig.
10Factorsinvolvedinthechoiceofaremediationtechnology.
Table2Environmentalfactorsaffectingbiodegradation.
ParametersConditionrequiredformicrobialactivityOptimumvalueforanoildegradationSoilmoisture25-28%ofwaterholdingcapacity30-90%SoilpH5.
5-8.
86.
5-8.
0OxygencontentAerobic,minimumair-filledporespaceof10%10-40%NutrientcontentNandpformicrobialgrowthC:N:P=100:10:1Temperature(oC)15-4520-30ContaminantsNottootoxicHydrocarbon5-10%ofdryweightofsoilHeavymetalsTotalcontent2000ppm700ppmTypeofsoilLowclayorsiltcontent10Environmentalbiotechnology.
MariaGavrilescuWastewateristypicallycategorizedintooneofthefol-lowinggroups(Wiesmannetal.
2007):xmunicipalwastewater(domesticwastewatermixedwitheffluentsfromcommercialandindustrialworks,pre-treatedornotpre-treated)xcommercialandindustrialwastewater(pre-treatedornotpre-treated)xagriculturalwastewatersTheeffluentcomponentsmaybeofchemical,physicalorbiologicalnatureandtheycaninduceanenvironmentalimpact,whichincludeschangesinaquatichabitatsandspe-ciesstructureaswellasinbiodiversityandwaterquality.
Somecharacteristicsofmunicipalandindustrialwaste-watersarepresentedinTables3and4.
Itisevidentthatthequalityparametersareverydiverse,sothatthebiologicalwastewatertreatmenthastobeade-quatetopollutionloading.
Therefore,itisadifficulttasktofindthemostappropriatemicroorganismconsortiaandtreatmentschemeforacertaintypeofwastewater,inordertoremovethenon-settleablecolloidalsolidsandtodegradespecificpollutantssuchasorganic,nitrogenandphosphoruscompounds,heavymetalsandchlorinatedcompoundscon-tainedinwastewater(Fig.
11)(MetcalfandEddy1991;Bitton2005).
Sincemanyofthesecompoundsaretoxictomicroor-ganisms,pretreatmentmayberequired(Burtonetal.
2002).
Biologicaltreatmentrequiresthattheeffluentsberichinunstableorganicmatter,sothatmicrobesbreakuptheseun-stableorganicpollutantsintostableproductslikeCO2,CO,NH3,CH4,H2S,etc.
(Cheremisinoff1996;GuestandSmith2002;Dunnetal.
2003).
Toanincreasingextent,wastewatertreatmentplantshavechangedfrom"end-of-pipe"unitstowardmodulesys-tems,mostofthemfullyintegratedintotheproductionTable3Typicalcharacteristicsofwastewaterfromvariousindustries.
Parameters(mg/L)Process/sourcepHTSSBOD5CODNPSCarbo-hydrateAceticacidMetha-nolCl-Na+Ca2+K+ReferencesPulpandpaperindustryThermomechanicalpulping(TMP)4.
281028005600122.
372270023525PokhrelandViraghavan2004Chemi-thermomecha-nicalpulping-5003000-40006000-9000--16710001500-Bajpai2000Kraftbleaching10.
137-74128-1841124-173840-76Bajpai2000;PokhrelandViraghavan2004Spentliguor-25313,30039,80086363156210320090Bajpai2000;DasandJain2001Chipwash-609512,00020,6008636315321082070Bajpai2000Papermill-80016005020110.
697610549Bajpai2000;PokhrelandViraghavan2004Pharmaceuticalindustry3.
98407342010asPO43-160asSO42-1,9002800200020Sirtarietal.
2009Syntheticdrugplant(1)2.
3-11.
111-1262980-37805480-7465262-5127.
95-45.
82900-4500Murthyetal.
1984Chemicalsynthesis-basedpharmaceutical7-8800-90040,000-60,0003-6PO4-POktemetal.
2007Syntheticdrugplant(2)7-871305900123703200asNO32--9000asSO42----1150--Dairyindustry5.
5-7.
5250-600350-6001500-3000Sarkaretal.
2006Cheeseindustry6.
2-11.
3326-3560565-5722785-761929-181263-12651.
4-58.
5Danalevichetal.
1998;HwangandHansen1998Milkprocessingplant8-11350-11001200-14002000-600020-50PO4-P170-20035-4035-40Ince1998;SamkuttiandGough2002Butter/milkpowderplant5-71500190835560813Donkui1997;Strydometal.
1997TextileindustryTextilefinishingindustry8.
6-8.
8250-750150-17017005-45N-NH414-30525-590SO42-1650-1750Eremektaretal.
2007Cottontextilewastewater9.
12-9.
60500-900800-12007-21NH4-N1.
95-2.
4915-3217750-34000KapdanandAlparslan2005Textilewastewater101501701150680SO42-1820Selcuk200511DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksprocess(productionintegrateenvironmentalprotection)(Rosenwinkeletal.
1999).
Thethreemajorgroupsofbiologicalprocesses:aerobic,anaerobic,combinationofaerobicandanaerobiccanberunincombinationorinsequencetooffergreaterlevelsoftreatment(Gradyetal.
1999;Burtonetal.
2002;Gavrilescu2004a).
Themainobjectivesofwastewatertreatmentpro-cessescanbesummarizedas:xreductionofbiodegradableorganicscontent(BOD5)xreduction/removalofrecalcitrantorganicsxremovalofheavy/toxicmetalsxremoval/reductionofcompoundscontainingpandn(nutrients)xremovalandinactivationofpathogenicmicroorga-nismsandparasites1.
AerobicbiotreatmentAerobicprocessesareoftenusedformunicipalandindus-trialwastewatertreatment.
Easilybiodegradableorganicmattercanbetreatedbythissystem(Wagneretal.
2002;DobleandKumar2005;GallertandWinter2005;Russell2006).
Thebasicreactioninaerobictreatmentplantisrepre-sentedbythereactions(1,2):(1)Microbialcellsundergoprogressiveauto-oxidationofthecellmass:(2)Lagoonsandlowratebiologicalfiltershaveonlylimi-tedindustrialapplications.
Theprocessescanbeexploitedassuspended(activatesludge)orattachedgrowth(fixedfilm)systems(GavrilescuandMacoveanu1999;Gradyetal.
1999;Gavrilescuetal.
2002a;Lupasteanuetal.
2004;Paveletal.
2004)(Fig.
12).
Aerationtanksusedfortheactivatedsludgeprocessallowssuspendedgrowthofbacterialbiomasstooccurduringbio-logical(secondary)wastewatertreatment,whiletricklingfilterssupportattachedgrowthofbiomass(Burtonetal.
2002;GavrilescuandMacoveanu2000;Gavrilescuetal.
2002b;GavrilescuandUngureanu2002;GallertandWinter2005)(Fig.
12).
Advancedtypesofactivatedsludgesystemsusepureoxygeninsteadofairandcanoperateathigherbiomassconcentration.
Biofilmreactorsareappliedforwastewatertreatmentinvariantssuchas:tricklefilters,rotatingdiskreactors,airliftreactors.
Domesticwastewatersareusuallytreatedbyaero-bicactivatedsludgeprocess,sincetheyarecomposedmainlyofproteins(40-60%),carbohydrates(25-50%),fatsandoils(10%),urea,alargenumberoftracerefractoryorganics(pesticides,surfactants,phenols(Bitton2005)(Table4).
cellsnewOHCOnutrientsothercellsOmaterialOrganico2223222NHOHCOOCellsoBIOLOGICALWASTEWATERTREATMENTACTIVATEDSLUDGEPROCESSBIOFILMPROCESSActivatedsludgetreatmentplantSingletanktechniqueCombinedprocessContinuousfeedDiscontinuousfeed(Sequencingbatchreactors)SubmergedbiofilmSprayedbiofilmTricklingfilterFixedbedreactorsFluidizedbedreactorsTricklingfilterSoilfilterSnady/gravelfilterSnady/gravelfilterConstructedwetlandFig.
12Processesandequipmentinvolvedinbiologicalwastewatertreatment.
Table4Typicalloadingofmunicipalwastewater(Bitton2005).
Concentration(mg/L)WastewatercharacteristicsStrongMediumWeakSuspendedsolids350220100Totalsolids1200720350BiochemicalOxygenDemand(BOD5)400220110ChemicalOxygenDemand(COD)1000500250NH3-N502512TotalN854020OrganicN35158TotalP1584SuspendedsolidsBiodegradableorganiccompoundsPathogensandparasitesNutrientsPrioritypollutantsDissolvedinorganicsHeavymetalsRefractoryorganicsWASTEWATERCONTAMINANTSFig.
11Categoriesofcontaminantsinwastewater.
(AdaptedfromMet-calfandEddy1991;Bitton2005).
12Environmentalbiotechnology.
MariaGavrilescu2.
AnaerobicbiotreatmentAnaerobictreatmentofwastewaterdoesnotgenerallyleadtolowpollutionstandards,anditisoftenconsideredapre-treatmentprocess,devotedtominimizationofoxygendemandandexcessiveformationofsludge.
Highlyconcen-tratedwastewatersshouldbetreatedanaerobicallyduetothepossibilitytorecoverenergyasbiogasandlowquantityofsludge(GallertandWinter1999).
Researchandpracticeshavedemonstratedthathighloadsofwastewatertreatedbyanaerobictechnologiesgene-rateslowquantitiesofbiologicalexcesssludgewithahightreatmentefficiency,lowcapitalcosts,nooxygenrequire-ments,methaneproduction,lownutrientrequirements(Fig.
13)(BlonskayaandVaalu2006).
NewdevelopmentsinanaerobicwastewatertreatmentHighrateanaerobicwastewatertreatmenttechnologiescanbeappliedtotreatdiluteconcentratedliquidorganicwaste-waterswhicharedischargedfromdistilleries,breweries,papermills,petrochemicalplantsetc.
Evenmunicipalwaste-watercanbetreatedusinghighrateanaerobictechnologies.
Therearealsoanumberofestablishedandemergingtech-nologieswithvariousapplications,suchas:-sulphatereductionforremovalandrecoveryofheavymetalsandsulphatedenitrificationfortheremovalofnitrates-bioremediationforbreakdownoftoxicprioritypol-lutantstoharmlessproducts.
SulphatereducingprocessThecharacteristicsofsomesulphur-richwastewaters(tem-perature,pH,salinity)aredeterminedbydischargingpro-cess.
Often,theyhavetomeetconstraintsimposedbyres-trictiveenvironmentalregulationssothatagrowinginteresttoextendtheapplicationofsulphatereducinganaerobicre-actionsinconditionsfarfromtheoptimalgrowthconditionsofmostbacteriaisobvious(Droste1997;GuestandSmith2002).
Themechanismofthesulphatereductionforremovaloforganics,heavymetalsandsulphurisillustratedbyreac-tions(3–5):(3)(4)(5)sulphateorganicsubstratedisulfidecarbondioxidesulfideheavymetal[soluble]metalsulfide[insoluble]disulfideoxygenelementalsulfur[insoluble]water2bacteriareducingsulfate24COHSCODSOopoMSMS22OHSOHS20)lusThilobacil.
eg(bacteriacchemotropi2poAerobictreatmentAnaerobictreatmentInlet100kgCODInlet100kgCODOutlet10kgCODSludge60kgCODOutlet10kgCODEnergy100kWhEnergy10kWhSludge10kgCODCO2,H2OMethane,CO2Fig.
13Comparisonofaerobicandanaerobicbiologicaltreatment.
(BlonskayaandVaalu2006).
OrganicsubstancesinwastewaterGreenhouseGas(CO2)GreenhouseGas(CH4)EnergySludgeDisposalOrganicsubstancesinwastewaterGreen-houseGas(CO2)BiomassReuseWastewaterTreatmentbyPhotosyntheticBacteriaConventionalWastewaterTreatmentFig.
14Comparisonofcarbonconversionpathwaysduringconventionalwastewatertreatmentandwastewatertreatmentbyphotosyntheticbacteria(Nakajimaetal.
2001).
13DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksUpflowanaerobicsludgeblanket(UASB)reactorscanbeusedtotreatsulphur-richwastewaters(Tuppurainenetal.
2002;Lensetal.
2004).
Wastewatertreatmentusingpurplenonsulphurbacteria,asortofphotosyntheticbacteriaunderlightandanaerobicconditionsisappliedtoproducealargeamountofusefulbiomasswithlittlecarbondioxide,oneofthemajorgreen-housegases(Fig.
14)(Nakajimaetal.
2001).
Thebiomassofthesebacteriacanbeutilizedforagriculturalandindus-trialpurposes,suchasafeedforfishandanimals,fertilizers,polyhydroxyalkanoates.
3.
AdvancedbiotreatmentAdvancedwastewaterbiotreatmentmustbeconsideredinaccordancewithvariousbeneficialreusepurposesaswellastheaspectofhumanandenvironmentalhealth.
Thisisespeciallyimportantwhenthetreatedwastewaterisaimedtousefortherehabilitationofurbancreakandcreationofwaterenvironmentalongit.
Membranetechnologyisconsideredoneoftheinnova-tiveandadvancedtechnologieswhichrationallyandeffec-tivelysatisfytheabovementionedneedsinwaterandwastewatertreatmentandreuse,sinceitcombinesbiologi-calwithphysicalprocesses(Yamamoto2001;Bitton2005).
Incombinationwithbiologicaltreatment,itisreason-ablyappliedtoorganicwastewaters,alargepartofwhichisbiodegradable.
Infact,thisisthecombinationofamem-braneprocesslikemicrofiltrationorultrafiltrationwithasuspendedgrowthbioreactor(BenAimandSemmens2003;Bitton2005)(Fig.
15).
Itiswidelyandsuccessfullyappliedinaneverincrea-singnumberoflocationsaroundtheworldformunicipalandindustrialwastewatertreatmentwithplantsizesupto80,000populationequivalent(MembraneSeparationActi-vatedSludgeProcess,MSAS).
Theprocessefficiencyisde-pendentonseveralfactors,suchasmembranecharacteris-tics,sludgecharacteristics,operatingconditions(Bitton2005;Judd2006).
AnewgenerationofMSASisthesubmergedtypewheremembranemodulesaredirectlyimmersedinanaera-tiontank(Fig.
15).
ThisaimstosignificantlyreducetheenergyconsumptionbyeliminatingabigcirculationpumptypicallyinstalledinaconventionalMSAS(Judd2006).
Membranebioreactors(MBR)canbeappliedforremo-valofdissolvedorganicsubstanceswithlowmolecularweights,whichcannotbeeliminatedbymembranesepara-tionalone,canbetakenup,brokendownandgasifiedbymicroorganismsorconvertedintopolymersasconstituentsofbacterialcells,therebyraisingthequalityoftreatedwater.
Also,polymericsubstancesretainedbythemembranescanbebrokendowniftheyarestillbiodegradable,whichmeansthattherewillbenoendlessaccumulationofthesubstanceswithinthetreatmentprocess.
This,however,re-quiresthebalancebetweentheproductionanddegradationrates,becausetheaccumulationofintermediatemetabolitesmaydecreasethemicrobialactivitiesinthereactor(Yama-AerationtankAerationtankA.
ExternalMembraneModuleB.
SubmergedMembraneModuleWastesludgeMembraneModulePermeateConcentratereturnPermeateWastesludgeQQMembraneModuleFig.
15Membranebioreactorswith(a)externalmoduleand(b)inter-nal(submerged)module.
(Bitton2005;BenAimandSemmens2003).
Table5ExpectedperformanceofMBRforwastewatertreatment.
WastewaterloadingExpectedperformanceSuspendedsolids(SS)CompleteremovalNoinfluenceofsludgesettleabilityoneffluentqualityRemovalofparticle-boundmicropollutantsVirus,bacteria,protozoaReliableremovalbysizeexclusion,retentionbydynamicmembrane,ahighremovalalongwithSSretentionNitrogenStablenitrificationduetohighretentionofnitrifyingbacteriaLowtemperaturenitrificationisattainedAhigheffectivenessfactorintermsofnitrificationduetorelativelysmallsizeflocEndogenousdenitrificationishighlyexpectedduetohighconcentrationofbiomassSludgestabilizationMinimizeexcesssludgeproductionduetolongSRTSludgetreatmentispossibletogetherwithwastewatertreatmentUseofhighertropicleveloforganismisexpectedtocontrolsludgeDegradationofhazardoussubstancesSelectivegrowthofspecificmicroorganismsisexpectedforhardlydegradablehazardoussubstancesAlmostpureculturesystemiseasilyoperatedTable6SustainabilitycriteriaforMBRtechnology(Balkemaetal.
2002;Fane2007).
CriteriaIndicatorsImprovementneededAppliednowwithgoodresultsEconomicCostandaffordabilityXXXEffluentwaterqualityMicroorganismSuspendedsolidsBiodegradableorganicsXNutrientremovalXChemicalusageXEnergyXEnvironmentalLanduseXReliabilityXEaseofusexFlexibleandadaptableXTechnicalSmall-scalesystemsXInstitutionalrequirementsXAcceptanceXSocio-culturalEpertiseX14Environmentalbiotechnology.
MariaGavrilescumoto2001).
MBRscanbeoperatedaerobicallyoranaerobicallyfororganiccompoundsandnutrientsremoval.
Duetoitshybridnature,MBRsofferadvantagesandgainmerits(Table5)(Yamamoto2001).
Thetechnologymeetswatersustainabilitycriteria,dis-cussesbyBitton(2005)andshowninTable6(Balkemaetal.
2002;Fane2007).
Themainadvantagesofbiologicalprocessesincompa-risonwithchemicaloxidationare:noneedtoseparatecol-loidsanddispersedsolidparticlesbeforetreatment,lowerenergyconsumption,theuseofopenreactors,resultinginlowercosts,andnoneedforwastegastreatment(Lang-waldtandPuhakka2000;Wiesmannetal.
2007).
4.
MoleculartechniquesinwastewatertreatmentAlthoughmoleculartechniqueapplicationsinwastewaterbiotreatmentarequitenew,beingdevelopedduringthe1990sandnotappearingtobemoreeconomicallythantheestablishedtechnologies,majorapplicationsmayincludetheenhancementofxenobioticsremovalinwastewatertreatmentplantsandtheuseofnucleicacidprobestodetectpathogensandparasites(COST6242001;Khanetal.
2004;Bitton2005;SanzandKochlung2007).
Amongthesetech-niques,themostinterestingprovedtobecloningandcrea-tionofgenelibrary,denaturantgradientcellelectrophoresis(DGGE),fluorescentinsituhybridizationwithDNAprobes(FISH)(SanzandKochlung2007).
Wastewatertreatmentprocessescanbeimprovedbyselectionofnovelmicroorganismsinordertoperformacer-tainaction.
However,theuseofDNAtechnologyinpol-lutioncontrolshowedtohavesomedisadvantagesandlimitations(Timmisetal.
1994;Bitton2005),suchas:multisteppathwaysinxenobioticsbiodegradation,limiteddegradation,instabilityoftherecombinantstrainsofinter-estintheenvironment,publicconcernaboutdeliberateoraccidentalreleaseofgeneticmodifiedmicroorganismsetc.
5.
MetalsremovalbymicroorganismsfromwastewatersHeavymetalscomeinwastewatertreatmentplantsfromindustrialdischarges,stormwateretc.
Toxicmetalsmaydamagethebiologicaltreatmentprocess,beingusuallyin-hibitorytobothareobicandanaerobicprocesses.
However,therearemicroorganismswithmetabolicactivityresultinginsolubilization,precipitation,chelation,biomethylation,volatilizationofheavymetals(BremerandGeesey1991;Bitton2005;Gerardi2006).
Metalsfromwastewatersuchasiron,copper,cadmium,nickel,uraniumcanbemostlycomplexedbyextracellularpolymersproducedbyseveraltypesofbacteria(B.
licheni-formis,Zooglearamigera).
Subsequently,metalscanbeac-cumulatedandthenreleasedfrombiomassbyacidictreat-ment.
Nonlivingimmobilizedbacteria,fungi,algaeareabletoremoveheavymetalsfromwastewater(EcclesandHunt1986;Bitton2005)(Table7).
Themechanismsinvolvedinmetalremovalfromwaste-waterinclude(Kulbatetal.
2003;Bitton2005;Gerardi2006):adsorptiontocellsurface,complexationandsolubi-lizationofmetals,precipitation,volatilization,intracellularaccumulationofmetals,redoxtransformationofmetals,useofrecombinantbacteria.
Forexample,Cd2+canbeaccumu-latedbybacteria,suchasE.
coli,B.
cereus,fungi(Asper-gillusniger).
Thehexavalentchromium(Cr6+)canbere-ducedtotrivalentchromium(Cr3+)bytheEnterobacterclo-acaestrain;subsequentlyCr3+precipitatesasametalhydro-xide(OhtakeandHardoyo1992).
SomemicroorganismscanalsotransformHg2+andseveralofitsorganiccom-pounds(methylmercury,ethylmercuricphosphate)tothevolatileformHg0,whichisinfactadetoxificationmecha-nism(SilverandMisra1988).
Themetabolicactivityofsomebacteria(Aeromonas,Flavobacterium)canbeexploitedtotransformSeleniumtovolatilealkylselenidesasaresultofmethylation(Bitton2005).
Table7Organismsinvolvedinmetalremoval/recoveryfromwaste-waters.
MetalOrganismYeastsSaccharomycescerevisiaeA.
pullulansCr.
laurentiiCy.
capitatumH.
anomalaP.
fermentansR.
rubraS.
cerevisiaeSp.
roseusS.
cerevisiaeentrappedinpolyurethanefoamCd(II)S.
cerevisiaemodifiedbycrosslinkingcystinewithglutaraldehydeCr(VI)Pb(II)Ni(II)S.
cerevisiaeCr(VI)CandidautilisCr(VI)S.
cerevisiaeCr(III)S.
cerevisiaeLivingmicroalgaefreeinsolutionChlorellavulgarisChlorellasalinaChlorellahomosphaeraScenedesmusobliquusChlamydomonasreinhardtiiAsterionellaformosaFragilariacrotonensisThalassiosirarotulaCd(II)CricosphaereelongateChlorellavulgarisPb(II)Euglenasp.
ChlorellavulgarisChlorellaregularisChlorellasalinaChlorellahomosphaeraZn(II)Euglenasp.
Au(I)ChlorellavulgarisChlorellaregularisChlorellasp.
ScenedesmusobliquusScenedesmussp.
Chlamydomonassp.
DunaliellatertiolectaU(II)Ankiistrodesmussp.
,Selenastrumsp.
ChlorellaregularisEuglenasp.
Cu(I)CricosphaereelongateChlorellaregularisNi(I)ThalassiosirarotulaChlorellaregularisCo(II)ChlorellasalinaChlorellaregularisChlorellasalinaMn(II)Euglenasp.
ChlorellaregularisScenedesmussp.
Mo(I)ChlamydomonasreinhardtiiChlorellaemersoniiScenedesmusobliquusTc(II)ChlamydomonasreinhardtiiChlorellaemersoniiScenedesmusobliquusZr(II)Chlamydomonassp.
Hg(II)Chlorellasp.
Al(III)Euglenasp.
15DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksSoilbioremediationSoilbiotreatmenttechnologiesuselivingorganismstodeg-radesoilcontaminants,eitherexsitu(i.
e.
,aboveground,inanotherplace)orinsitu(i.
e.
,inplace,inground),andin-cludebiotreatmentcells,soilpiles,andpreparedtreatmentbeds(TrejoandQuintero1999;Khanetal.
2004;Gavri-lescu2006).
Forbioremediationtobeeffective,microorganismsmustenzymaticallyattackthepollutantsandconvertthemtoharmlessproducts.
Sincebioremediationcanbeeffectiveonlywhereenvironmentalconditionspermitmicrobialgrowthandactivity,itsapplicationofteninvolvesthemani-pulationofenvironmentalparameterstoallowmicrobialgrowthanddegradationtoproceedatafasterrate.
Table2reviewssomeenvironmentalconditionsfordegradationofcontaminants(Vidali2001).
Oilbioremediationistypicallybasedontheprinciplesofsoilcompostingthatmeanscontrolleddecompositionofmatterbybacteriaandfungiintoahumus-likeproduct.
Thisprocesscanbeperformedinanexsitusystem,whencon-taminatedsoilsareexcavated,mixedwithadditionalsoiland/orbacteriatoenhancetherateofdegradation,andplacedinabovegroundareasortreatmentcompartments.
Anothertypeofsoilbiotreatmentconsistsofaninsituprocess,whenacarbonsourcesuchasmanureisadded,inanactiveorpassiveproceduredependinguponwhetherthecarbonsourceisapplieddirectlytotheundisturbedsoilsur-face(i.
e.
,passive)orphysicallymixedintothesoilsurfacelayer(i.
e.
,active).
Table8summarizessomeoftheadvantagesanddisad-vantagesofsoilbioremediationtechniques(Vidali2001;Gavrilescu2006;Gavrilescuetal.
2008;PavelandGavri-lescu2008).
Bothinsituandexsitumethodsarecommerciallyex-ploitedforthecleanupofsoilandtheassociatedground-water(LangwaldtandPuhakka2000).
Theeffectivenessofbothalternativesisdependentuponcarefulmonitoringandcontrolofenvironmentalfactorssuchasmoisture,tempera-ture,oxygen,andpH,andtheavailabilityofafoodsourceforthebacteriatoconsume(Saval1999).
Bioremediationofland(biorestoration)isoftencheaperthanphysicalmethodsanditsproductsareharmlessifcom-pletemineralizationtakesplace.
Itsactioncan,however,betime-consuming,tyingupcapitalandland.
Bioremediationusingplants,identifiedasphytoreme-diation(Fig.
5)ispresentlyusedtoremovemetalsfromcontaminatedsoilsandgroundwaterandisbeingfurtherexploredfortheremediationofotherpollutants.
Certainplantshavealsobeenfoundtoabsorbtoxicmetalssuchasmercury,leadandarsenicfrompollutedsoilsandwater,andscientistsarehopefulthattheycanbeusedtotreatindus-trialwaste.
Vidali(2001)describedfivetypesofphytoremediationtechniques,classifiedbasedonthecontaminantfate:phyto-extraction,phytotransformation,phytostabilization,phyto-Table7(Cont.
)MetalOrganismMacroalgalbiomassSargassumnatansAscophyllumnodosumHalimedaopuntiaCd(II)FucusvesiculosusSargassumnatansSargassumfluitansSargassumvulgarisAscophyllumnodosumPalmariapalmateChondrusCrispusFucusvesiculosusPadinagymnosporaPb(II)CodiumtayloriSargassumnatansAscophyllumnodosumPalmariapalmateChondrusCrispusAu(I)PorphyrapalmataAg(I)SargassumnatansU(II)SargassumnatansZn(II)SargassumnatansSargassumnatansCu(I)VaucheriaSargassumnatansAscophyllumnodosumChondrusCrispusPorphyrapalmataCo(II)HalimedaopuntiaSr(II)VaucheriaTable8Summaryofsomebioremediationstrategies.
TechnologyExamplesBenefitsLimitationsFactorstoconsiderInsituInsitubioremediationBiospargingBioventingBioaugmentationMostcostefficientNoninvasiveRelativelypassiveNaturalattenuationprocessesTreatssoilandwaterEnvironmentalconstrainsExtendedtreatmenttimeMonitoringdifficultiesBiodegradativeabilitiesofindigenousmicroorganismsPresenceofmetalsamdotherinorganicsEnvironmentalparametersBiodegradabilityofpollutantsChemicalsolubilityGeologicalfactorsDistributionofpollutantsExsituLandfarmingCompostingBiopilesCostefficientLowcostCanbedoneonsiteSpacerequirementsExtendedtreatmenttimeNeedtocontrolabioticlossMasstransferproblemBioavailabilitylimitationSeeaboveBioreactorsSlurryreactorsAqueousreactorsRapiddegradationkineticOptimizedenvironmentalparametersEnhancesmasstransferEffectiveuseofinoculantsandsurfactantsSoilrequiresexcavationRelativelyhighcostcapitalRelativelyhighoperatingcostSeeaboveBioaugmentationToxicityofamendmentsToxicconcentrationofcontaminantsBiopilesex-situmethodsitedundercoveredstructures,bundedtomanageleachategenerationthephysicalcharacteristicsofbiopilesaredifficulttoengineerusingvariousmethodstoenhancethegrowthandviabilityofthemicrobesWindrowsex-situmethodpilesofcontaminatedsolids,fashionedtomaximiseoxygenavailability,coveredwithreadily-removablestructures,andbundedtomanageleachategenerationthemethodisoftenpreferredsinceeaseofengineeringensuresthemicroorganismsareindirectcontactwithcontaminantsmoisturecontent,nutrientlevels,pHadjustment,andbiologicalmaterialmaintenanceisfacilitatedbyrecirculationofgeneratedleachate,withanynecessarysupplements16Environmentalbiotechnology.
MariaGavrilescudegradation,rhizofiltration,andsummarizessomephyto-remediationmechanismsandapplications(Table9).
Togetherwithothernear-naturalprocessesandthemonitorednaturalattenuationprocedures,sustainablestra-tegieshavetobedevelopedtoovercomethecomplexprob-lemsofcontaminatedsites(GallertandWinter2005).
SolidwastebiotreatmentTheimplementationofincreasinglystringentstandardsforthedischargeofwastesintotheenvironment,aswellastheincreaseincostofhabitualdisposalortreatmentoptions,hasmotivatedthedevelopmentofdifferentprocessesfortheproductionofgoodsandforthetreatmentanddisposalofwastes(Nicell2003;Hameretal.
2007;MazzantiandZoboli2008).
Theseprocessesaredevelopedtomeetoneormoreofthefollowingobjectives(EvansandFurlong2003;Gavrilescuetal.
2005,BanksandStentiford2007):(1)toimprovetheefficiencyofutilizationofrawmaterials,there-byconservingresourcesandreducingcosts;(2)torecyclewastestreamswithinagivenfacilityandtominimizetheneedforeffluentdisposal;(3)toreducethequantityandmaximizethequalityofeffluentwastestreamsthatarecre-atedduringproductionofgoods;and(4)totransformwastesintomarketableproducts.
Themultitudesofwaysinwhichthetransformationofwastesandpollutantscanbecarriedoutcanbeclassifiedasbeingchemicalorbiologicalinnature.
Biotreatmentcanbeusedtodetoxifyprocesswastestreamsatthesource–beforetheycontaminatetheenvironment–ratherthanatthepointofdisposal.
Infact,wasterepresentsoneofthekeyinterventionpointsofthepotentialuseofenvironmen-talbiotechnology(EvansandFurlong2003).
Biowasteisgeneratedfromvariousanthropogenicacti-vities(households,agriculture,horticulture,forestry,waste-watertreatmentplants),andcanbecategorizedas:manures,rawplantmatter,processwaste.
Forexample,inEurope,40–60%ofmunicipalsolidwastes(MSW)consistofbio-waste,mostofitcollectedseparatelyandusedformanyap-plicationssuchasaerobicdegradationorcomposting,whichcanprovide(throughanaerobicdegradationorfer-mentation)nutrientsandhumuscompoundsforimprovingthesoilstructureandcompostqualityforagricultureusesprovidesnutrientsinsoilandcompostforagricultureuses.
Theenergyoutputisbiogas,whichcanbeusedasenergysourcee.
g.
togenerateelectricityandheat(Fischer2008).
Thepotentialfornutrientandhumusrecyclingfrombio-wastebackintothesoil,viacomposted,digestedorother-wisebiologicallytreatedmaterialwasoftenmentioned.
Thisapproachinvolvescarefullyselectingorganisms,knownasbiocatalysts,whichareenzymesthatdegradespe-cificcompounds,anddefinetheconditionsthatacceleratethedegradationprocess.
Biologicalwastetreatmentaimstothedecompositionofbiowastebyorganismsinmorestable,bulk-reducedmate-rial,whichcontributesto:-reducingthepotentialforadverseeffectstotheenvi-ronmentorhumanhealth-reclaimingvaluablemineralsforreuse-generatingausefulendproductAdvantagesofthebiologicaltreatmentinclude:stabili-zationofthewaste,reducedvolumeinthewastematerial,destructionofpathogensinthewastematerial,andproduc-tionofbiogasforenergyuse.
Theendproductsofthebiolo-gicaltreatmentcan,dependingonitsquality,berecycledasfertilizerandsoilamendment,orbedisposed.
Solidwastecanbetreatedbybiochemicalmeans,eitherinsituorexsitu(Dobleetal.
2004).
Thetreatmentscouldbeperformedasaerobicoranaerobicdependingonwhe-thertheprocessrequiresoxygenornot.
1.
AnaerobicdigestionAnaerobicdigestionoforganicwasteacceleratesthenatu-raldecompositionoforganicmaterialwithoutoxygenbymaintainingthetemperature,moisturecontentandpHclosetotheiroptimumvalues.
GeneratedCH4canbeusedtopro-duceheatand/orelectricity(Mata-Alvarezetal.
2000;Sal-minenandRintala2002).
Themostcommonapplicationssolid-wastebiotreat-mentinclude(TBVGmbH2000):xtheanaerobictreatmentofbiogenicwastefromhumansettlementsxtheco-fermentationofseparatelycollectedbiode-gradablewastewithagriculturaland/orindustrialsolidandliquidwastexco-fermentationofseparatelycollectedbiodegrade-blewasteinthedigestingtowersofmunicipalwastetreatmentfacilitiesxfermentationoftheresidualmixedwastefractionwithinthescopeofamechanical-biologicalwaste-treat-mentconceptAnaerobicprocessesconsumelessenergy,producelowexcesssludge,andmaintainenclosureofodoroverconven-tionalaerobicprocess.
Thistechniqueisalsosuitablewhentheorganiccontentoftheliquideffluentishigh.
Theacti-vityofanaerobicmicrobescanbetechnologicallyexploitedunderdifferentsetsofconditionsandindifferentkindsofprocesses,allofwhich,however,relyontheexclusionofoxygen(TBVGmbH2000).
ImportantcharacteristicsandrequisitespecificationsforclassifyingthevariousfermentationprocessesandessentialstepsinthetreatmentoforganicwastewerepresentedinTable10(TBVGmbH2000).
2.
CompostingThebiologicaldecompositionoftheorganiccompoundsofwastesundercontrolledaerobicconditionsbycompostingislargelyappliedforwastebiotreatment.
Theeffectiverecyclingofbiowastethroughcompostingordigestioncantransformapotentiallyproblematic'waste'intoavaluable'product':compost.
Almostanyorganicwastecanbetreatedbythismethod(Haug1993;KrogmannandKrner2000;Kutzner2000;Schuchardt2005),whichresultsinendproductsasbiologicallystablehumus-likeproductforuseasasoilconditioner,fertilizer,biofiltermaterial,orfuel.
Degradationoftheorganiccompoundsinwasteduringcompostingisinitiatedpredominatelybyaverydissimilarcommunityofmicroorganisms:bacteria,actinomyctes,andfungi.
AnadditionalinoculumforthecompostingprocessisTable9Overviewofphytoremediationapplications.
TechniquePlantmechanismSurfacemediumPhytoextractionUptakeandconcentrationofmetalviadirectuptakeintotheplanttissuewithsubsequentremovaloftheplantsSoilsPhytotransformationPlantuptakeanddegradationoforganiccompoundsSurfacewater,groundwaterPhytostabilizationRootexudatescausemetaltoprecipitateandbecomelessavailableSoils,groundwater,minetailingPhytodegradationEnhancesmicrobialdegradationinrhizosphereSoils,groundwaterwithinrhizosphereRhizofiltrationUptakeofmetalsintoplantrootsSurfacewaterandwaterpumpedPhytovolatilizationPlantsevapotranspirateselenium,mercury,andvolatilehydrocarbonsSoilsandgroundwaterVegetativecapRainwaterisevapotranspiratedbyplantstopreventleachingcontaminantsfromdisposalsitesSoils17DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksnotgenerallynecessary,becauseofthehighnumberofmicroorganismsinthewasteitselfandtheirshortgenera-tiontime.
Alargefractionofthedegradableorganiccarbon(DOC)inthewastematerialisconvertedintocarbondioxide(CO2).
CH4isformedinanaerobicsectionsofthecompost,butitisoxidizedtoalargeextentintheaerobicsectionsofthecompost.
TheestimatedCH4releasedintotheatmosphererangesfromlessthan1%toafewpercentoftheinitialcarboncontentinthematerial(Beck-Friis2001).
Compostingcanleadtowastestabilization,volumeandmassreduction,drying,eliminationofphytotoxicsubstan-cesandundesiredseedsandplantparts,andsanitation.
Compostingisalsoamethodforrestorationofcontami-natedsoils.
Sourceseparatedbio-wastescanbeconvertedtoavalu-ableresourcebycompostingoranaerobicdigestion.
Inre-centyears,bothprocesseshaveseenremarkabledevelop-mentsintermsofprocessdesignandcontrol.
Inmanyres-pects,compostinganddigestiondifferfromotherwastemanagementprocessesinthattheycanbecarriedoutatvaryingscalesofsizeandcomplexity.
Therefore,thisen-ablesregionstoimplementarangeofdifferentsolutions:largeandsmall-scalesystems,acentralizedordecentralizedapproach(Gilbertetal2006).
3.
Mechanical-biologicaltreatmentMechanical-biological(MB)treatmentofwasteisbecomingpopularinEurope(Steiner2005).
InMBtreatment,thewastematerialundergoesaseriesofmechanicalandbiolo-gicaloperationsthataimtoreducethevolumeofthewasteaswellasstabilizeittoreduceemissionsfromfinaldispo-sal.
BiotreatmentofgaseousstreamsInthewastegastreatments(odoursandvolatileorganiccompounds,VOC)biotechnologyhasbeenappliedtofindgreenandlowcostenvironmentalprocesses(Devinnyetal.
1999;PenciuandGavrilescu2003;LeCloirecetal.
2005).
Odorousemissionsrepresentaseriousproblemrelatedtobiowastetreatmentfacilitiesastheymaybeatroubletothelocalresidentssincetheymayresultincomplaintsandalackofacceptanceofthefacilitybecauseodoursmaybecarriedawayseveralkilometers,dependingonweatherandtopographicalconditions(Hérouxetal.
2004).
Table11showsthesubstancesanalyzedintheexhaustairofanenclosedcompostingfacility.
AscanbeseenfromTable11theexhaustairmainlycontainsalcohols,esters,ketonesandaldehydes,aswellasterpenes(Schlegelmilchetal.
2005).
Mostofthemareproductsofbiologicaldegra-dation,withalcohols,esters,ketones,holdingthemainpor-Table10Systematicoverviewoffermentationprocessesandessentialstepsinthetreatmentoforganicwaste(TBVGmbH2000).
1.
Requirementsconcerningthecompositionoftheinputmaterial(s)i.
e.
:limits,e.
g.
,TScontent,fibercontentandlength,particlesize,viscosity,foreign-substancecontent2.
Pretreatmentforreducingthepollutantandinert-materialcontentse.
g.
:manualsorting,mechanical/magneticseparation,wetprocessing3.
Pretreatmentrequiredfortheprocesse.
g.
:sizereductionandsubstanceexclusion:mechanical,chemical,enzymatic,thermal,bacteriological[methods,employedprocessadditives]TS-contentrange:admixtureofprocesswater[dry/wetfermentationprocesses],monochargesrequiringadmixtureofotherfermentablestartingmaterials4.
Processesa1)Single-phasefermentationa2)Two-phasefermentationSingle-stageprocessMultiple-stageprocessStationarysolidphase/mobileliquidphaseMobilesolidphase/StationaryliquidphaseUpgrading(concentration)Downgrading(deconcentration)b)Fermentationtemperaturerange(s)(mesophilic/thermophilic)c)Stirring/mixing-stirring/mixingsystemd)Interstageconveyance[e.
g.
,pump,gravimetric]e)In-processseparationofsediments/floatingmatterf)Retentiontime(s)g)Equipmentforcontrollingtheprocessmilieuh)Phaseseparationattheendoffermentation5.
Post-treatmentprocessesSecondaryfermentation(e.
g.
,timespanfordegreeoffermentationV,timehistoryoftemperatureduringsecondaryfermentation),drying,disinfection,reductionof(nutrient)salinity,wastewatertreatment6.
Endproduct(s)i.
e.
:specificationaccordingtorecognizedcriteriae.
g.
,degreeoffermentation,degreeofhygienization,nitrate/saltcontentTable11Chemicalcompositionofwastegasofcompostingplant(Heroldetal.
2002).
AlcoholsEstersKetones/aldehydesTerpenesOthersEthanolEthylacetateAcetone-PineneAceticacidButanol(2)EthylpropionateButanoneCamphene2-Ethylfurane2-Me-propanolPropylacetate3-Me-butanal-PhellandreneToulenen-ButanolEthylbutyrate3-Me-butanone(2)-PineneXyleneCyclopentanoli-ButylacetatePentanone(2)-MyrceneDibutylphthalate3-Me-butanol(1)MethylbutyrateMe-isobutylketone3-CareneBis-2-Ethylhexyl-adipinate2-Me-butanol(1)PropylpropionateHexanone(2)Limonenen-PentanolMethylpentoate5-Me-Hexanone(2)Thujonen-HexanolEt-2-Me-butyrateBenzaldehydeCamphorPropylbutyrateNonanalThymolEthylpentanoateDecanalThujopreneMethylhexanoateBornylacetateEthylhexanoatePropylhexaonateEthylheptanoate18Environmentalbiotechnology.
MariaGavrilescution(Heroldetal.
2002;Schlegelmilchetal.
2005).
Biofiltersareoneofthemainbiologicalsystemsused,whichworkatnormaloperatingconditionsoftemperatureandpressure.
Thereforetheyarerelativelycheap,withhighefficiencieswhenthewastegasischaracterizedbyhighflowandlowpollutantconcentration(Gavrilescuetal.
2005;Andresetal.
2006).
Biologicalwasteairtreatmentusingbiofiltersandbiotricklingfilterswasdevelopedasareliableandcost-effectivetechnologyfortreatmentofpol-lutedairstreams(Cohen2001;Coxetal.
2001;Iranpouretal.
2002;Penciuetal.
2004).
Thebiodegradationofpol-lutantsbymicroorganismsleadstoharmlessend-products(KennesandThalasso1998;PenciuandGavrilescu2004).
Becausemicrobialpopulationsinbiofiltersandbiotricklingfiltersgenerallyareverydiverse,thesetypesofreactorscansimultaneouslyremovecomplexmixturesofpollutants,whichwouldotherwiserequireaseriesofalternativetech-nologies(Deshusses1997;CoxandDeshusses1998;CoxandDeshusses2001;KennesandVeiga2001;Shareefdeenetal.
2005).
Bioscrubber/biofiltercombinationsalsoprovedtobeanefficientsystemtotreatodorousoff-gasesfromcompostingprocesses.
Resultsrevealedthatthemainpartoftheodourloadwasdegradedwithinthebiofilter(Schlegelmilchetal.
2005).
BiodegradationofhydrocarbonsHydrocarbonscangeneratesignificantpollutionbecausetheyareamongthemostcommoncontaminantsofground-water,soilandseawhenoilisspilled(Mohn1997;Staple-tonetal.
1998).
Thedamagecausedbyoilspillsinmarineorfreshwatersystemsisusuallycausedbythewater-in-oilemulsion.
Varioustypesofmicroorganismscandegradehydrocar-bons:bacteria,yeasts,filamentousfungi,butnoneofthemdegradeallofthepossiblehydrocarbonmoleculesatthesamerate.
Eachorganismmayhaveadifferentspectrumofactivityandadefinitepreferentialuseofcertainchainlengthshydrocarbonstructures.
Almostallpetroleumhydrocarbonscanbeoxidizedtomainlywaterandcarbondioxide,buttherateatwhichtheprocesstakesplaceisdependentontheirnature,amountandthephysicalandchemicalpropertiesthatinfluencetheirpersistenceandbiodegradability(Atlas1981;LeahyandColwell1990;EIBE2000;BaheriandMeysami2002;Tor-kianetal.
2003).
Hydrocarbonsaresubjecttobothaerobicandanaerobicoxidation.
Usually,thefirststageofbiodeg-radationofinsolublehydrocarbonsispredominantlyaero-bic,whiletheorganiccarboncontentisreducedbytheac-tionofanaerobicorganisms.
Table12presentssomegroupsofmicroorganismsthatcandegradevarioushydrocarbons,whileinTable13theadequacyofaerobicoranaerobicdeg-radationisdoneaccordingtovarioustypesofcontaminantsfrompetroleumderivatives.
Theprevailingenvironmentalfactorsandthetypes,numbersandcapabilitiesofthemicroorganismspresentaf-fectthebiodegradationoccurrenceandrate.
Factorsaffec-tinghydrocarbonbiodegradationincontaminatedsoilscanbe:theoccurrenceofoptimalenvironmentalconditionstostimulatebiodegradativeactivity;thepredominanthydro-carbontypesinthecontaminatedmatrix;thebioavailabilityofthecontaminantstomicroorganisms;dispersionandemulsificationenhancingratesinaquaticsystemsandab-sorptionbysoilparticulates(LeahyandColwell1990;Kastneretal.
1998;Marques-Rochaetal.
2000).
Hydrocarbonshavedifferentsolubilityinwaterwheretheyareonlydegraded.
Duetodifferenthydrophobicityandlowsolubilityinwaterofthehydrocarbons,theprocessshouldbeintensifiedbyenhancingphysicalcontactbetweenmicroorganismsandoilbyaddingadjuvantstoimprovethecontactareasorbyinjectingofmixturesofmicroorganisms,duringtheso-calledbioaugmentation(BaheriandMeysami2002;Baptistaetal.
2006;MalinaandZawierucha2007).
Itisalsoknownthattheactivityofbacteriaandfungiabletooxidizehydrocarbonscouldbeimprovedbysup-plementationwithvariousnutrients(sourcesofnitrogenandphosphorous).
Differentorganismsneeddifferenttypesofnutrients.
Bioenhancementisappliedtostimulatetheacti-vityofbacteriaalreadypresentinthesoilatawastesitebyaddingdifferentnutrients(BaheriandMeysami2002;GuptaandSeagren2005).
BiosorptionBiosorptionisafastandreversibleprocessfortheremovaloftoxicmetalionsfromwastewaterbyliveordriedbio-mass,whichresemblesadsorptionandinsomecasesionexchange(Volesky1990;Voleskyetal.
1993;Seideletal.
2002;Gavrilescu2004a).
Thebiosorptionoffersanalterna-tivetotheremediationofindustrialeffluentsaswellastherecoveryofmetalscontainedinothermedia.
Biosorbentsarepreparedfromnaturallyabundantand/orwastebiomass.
Duetothehighuptakecapacityandverycost-effectivesourceoftherawmaterial,biosorptionisaprogressiontowardsaperspectivemethod.
Ithasbeendemonstratedthatbothlivingandnon-livingbiomassmaybeutilizedinbiosorptiveprocesses,astheyoftenexhibitamarkedtolerancetowardsmetalsandotheradversecondi-tions(BrinzaandGavrilescu2003;Gavrilescu2004a,2005;Table12Degradationofpetroleumcompoundsandfuelcomponentsbydifferentgroupsofmicroorganisms(Riser-Roberts1998).
MicroorganismCompoundYeastsThrichosporon,Pichiarhodosporidium,Rhodotorula,Debraryomyces,Endomycopsis,Candidaparapsilasis,C.
tropicalis,C.
guilliermondii,C.
lipolytica,C.
maltosa,Debaramyceshansenii,Trichosporonsp.
,RhodosporiumtaruloidlesHexadecaneandkerosene(naphthalene,biphenyl,benzo(a)pyrene)ActinomycetesNocardiaspp.
n-Paraffins:pentane,hexane,heptane,octane,2-methylbutane,2-methylpentane,3-methylpentane,2,2,4-trimethylpentane,ethylbenzene,hexadecane,keroseneAlgaeSelanastrumcapricornatumBenzene,toluene,naphthalene,phenanthrene,pyreneCyanobacteria(blue-greenalgae)MicrocystisaeruginosaBenzene,toluene,naphthalene,phenanthrene,pyreneMixedcultures(yeasts,molds,protozoa,bacteria;activatedsludge)AcrylonitrileActivatedsludgeDibenzanthraceneSewagesludgeFluorantheneAcinetobactercalcoaceticusPetroleumderivatesStrainsofPseudomonasputidaPhenolcresolsTrichosporonpullulansParaffinsAeromoniumsp.
TotalpetroleumhydrocarbonsMycobacteriumsp.
n-Undecane19DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksKicsietal.
2006a,2006b;Brinzaetal.
2007).
Metalionscanbindtocellsbydifferentphysiochemicalmechanisms,dependingonthebacterialstrainandenviron-mentalconditions(Fig.
7).
Becauseofthisvariability,cur-rentknowledgeoftheseprocessesisincomplete.
Ingeneral,bacterialcellwallsarepolyelectrolytesandinteractwithionsinsolutionsoastomaintainelectroneutrality.
Themechanismsbywhichmetalionsbindontothecellsurfacemostlikelyincludeelectrostaticinteractions,vanderWaalsforces,covalentbonding,redoxinteractions,andextracel-lularprecipitation,orsomecombinationoftheseprocesses(Blanco2000;Gavrilescu2004a).
Biosorptionofheavymetalsbyalgalbiomassisanadvantageousalternative,anappropriateandeconomicallyfeasiblemethodusedforwastewaterandwastecleanup,becauseitusesalgalbiomasssometimesconsideredwastefromsomebiotechnologicalprocesses(Sandauetal.
1996;FengandAldrich,2004;Vilaretal.
2007)orsimplyitshighavailabilityincostalareasmakesitsuitablefordevelopingnewby-productsforwastewatertreatmentplants(Sandauetal.
1996;Brinzaetal.
2005a,2005b;Brinzaetal.
2007).
BiodegradationofrefractorypollutantsandwasteThebiodegradabilityofrefractorypollutantswasinvesti-gatedandappliedbynumerousresearchers,sincethisbecomesmoreandmoreastringentproblemoftheenviron-mentbecauseofpreviousorcurrentpollution.
1.
CyanideremovalEffluentscontainingcyanidefromvariousindustriesmustbetreatedbeforedischargingintotheenvironment.
Theconventionalphysico-chemicalprocessesforremovalofcyanidesfromwastewaterprovedtopresentadvantages,butalsodisadvantagesburdenedwithhighreagentandliabilitycosts.
Bioremoval/biotreatmentwasseenasanenvironmen-tallyfriendlyalternativetreatmentprocessabletoachievehighdegradationefficiencyatlowcosts(Camposetal.
2006;Dashetal.
2008;Chenetal.
2008;Dashetal.
2009).
Inbiologicaltreatmentofcyanide,bacteriaconvertfreeandmetal-complexcyanidestobicarbonateandammonia.
Thefreemetalsarefurtheradsorbedorprecipitatedfromsolu-tion.
Themicroorganismsresponsibleforcyanidedegrada-tioncouldbebacteriaorfungi,whichusecyanideasasourceofnitrogenandcarbon(Table14).
2.
DistilleryspentwashThisisaliquidwastegeneratedduringalcoholproduction,whichconfersunpleasantodorsforwastewater,posingaseriousthreattowaterquality.
Disposalofdistilleryspentwashonlandismoreoverhazardoustothevegetation,sinceitreducessoilalkalinityandmanganeseavailability,thusinhibitingseedregeneration(Kumaretal.
1997;Mohanaetal.
2009).
Anumberofcleanuptechnologiesareusedtoprocessthiseffluentefficientlyandeconomicallyandnovelbiore-mediationapproachesfortreatmentofdistilleryspentwasharebeingworkedout(Table14).
3.
RadionuclidesRadionuclidelikeuraniumorthoriumareofparticularcon-cerninenvironmentalimpactandremediationresearchesduetotheirhightoxicityandlonghalf-lives,thustheyareconsideredsevereecologicalandpublichealthhazards(Gavrilescuetal.
2008;Kazietal.
2008)(Table14).
Biosorptiveaccumulationofuraniumandotherradio-nuclidesisofgreatinterestforthedevelopmentofmicrobe-basedbioremediationstrategies(Kazietal.
2008).
4.
HeavymetalsTheapplicationofbiotechnologicalprocessesfortheeffec-tiveremovalofheavymetalsfromcontaminatedwaste-watershasemergedasanalternativetoconventionalreme-diationtechniques.
Heavymetalpollutionisusuallygene-ratedfromelectroplating,plasticsmanufacturing,fertilizers,pigments,mining,andmetalurgicalprocesses(Gavrilescu2004b;Zamboulisetal.
2004).
Theapplicationofconventionaltreatmentsissome-timesrestrictedduetotechnologicalandeconomicalcon-straints.
Metalaccumulationonbiomasscanbepassive(bio-sorptive),whennon-livingbiomassisusedasbiosorbent,orTable13Somecontaminantsaspetroleumderivativesremovablethroughbioremediation(Vidali2001).
ContaminantsBiotreatmentClassExamplesAerobicAnaerobicPotentialsourcesChlorinatedsolventsTrichloroethylenePerchloroethyleneinsitubioremediation-reductivedechlorationwithfreshcheesewheyasasubstrateDrycleanersChemicalmanufacturePolychlorinatedbiphenyls4-Chlorobiphenyl4,4-DichlorobiphenylyesElectricalmanufacturingPowerstationRailwayyardsChlorinatedphenolsPentachlorophenolTrichlorophenolTetrachlorophenolyesTimbertreatmentLandfillsinsituaerobicbiodegradation-indigenoussoilbacteriarespirationactivitystimulatedwithairinput(venting,airsparging)andnutirentsolutiondeliveryBTEXBenzeneTolueneEthylbenzeneXylenein-situbioremediation(i.
e.
aerobicenhancementbyfertilizerandnutrientadditionplusapplicationofchosenallochthonousbacterialstrains)yesOilproductionandstorageGasworksitesAirportsPaintmanufacturePortfacilitiesRailwayyardsChemicalmanufacturePolyaromatichydrocarbons(PAHs)NaphthaleneAntraceneFluorenePyreneBenzo(a)pyreneyesOilproductionandstorageGasworksitesCokeplantsEngineworksLandfillsTarproductionandstorageBoilerashdumpsitesPowerstations20Environmentalbiotechnology.
MariaGavrilescuTable14Removalmethodsforsomerefractorypollutantsandwaste.
CompoundsRemovalmethodAdvantagesDisadvantagesReferencesCyanideBiologicaloxidation/biodegradation-hydrolyticreactions-oxidativereactions-reductivereactions-substitution/transferreactionsNaturalapproach,receivedwellbypublicandbyregulatorsUseheapsasreactors,reducingtotalwashedvolume,andpossiblereachlowflowareasoftheheapmoreeffectivelyRelativelyinexpensiveNochemicalhandlingequipmentorexpensivecontrolneededBiomasscanbeactivatedbyaerationNotoxicby-productsCantreatcyanideswithoutgeneratinganotherwastestreamInnovativetechnologynotwellestablishedTendstobeverysitespecificwithspecificevaluationandstudyrequiredforeachtypeofcompoundandsiteCannottreathighconcentrationPatilandPakniar2000Camposetal.
2006Chenetal.
2008Dashetal.
2008Dashetal.
2009DistilleryspentwashBiodegradation:-Anaerobicsystemsxsinglephase,biphasicsystemxanaerobiclagoonsxhighrateanaerobicreactors-Aerobicsystems(mayfollowtheanaerobictreatment)xfungalsystemsxbacterialsystemsxcyanobacterial/algalsystemsxphytoremediation/constructedwetlandsBiomethanationofdistilleryspentwashisawellestablishedtechnologyBiologicalaerobictreatmentemployingfungiandbacteriaisveryeffectiveforthedecolorizationofdistilleryspentwashResearchonadvancedanaerobictreatmenttechnologiesarefurthernecessarytobringintopracticeoutstandingtechnologiesforecologicalrestorationAerobictreatmentneedstobeimplementedwithadditionalnutrientsaswellasdilutingtheeffluentforobtainingoptimalmicrobialactivityNeedstobesometimescombinedsequentiallywithphysico-chemicaltreatmentKumaretal.
1997Fitzgibbonetal.
2007Kumaretal.
2007Mohanaetal.
2009SatyawaliandBalakrishanan2008Mohanaetal.
2009Radionuclides(Uranium,Thorium)Biosorption/microbebasedimmobilization-sequestrationInnovative/emergingtechnology,stilltobestudiedinmoredetailsGavrilescuetal.
2008HeavymetalsBiosorptionusingbiomaterials,bacteria,fungi,yeasts,algae,naturalmaterials,industrialandagriculturalwasteCost-effectivebiotechnologyforthetreatmentofhighvolumeandlowconcentrationcomplexwastewaters(1-100mg/L)MicroorganismsprovidealargecontactareathatcaninteractwithmetalBiosorptionisbasicallyatlabscaleinspiteofitsdevelopmentforyearsThemechanismisnotfullyunderstoodandshortcomingsofbiosorptiontechnologylimitapplicationBeolcini1977Gavrilescu2004Zouboulisetal.
2004WangandChen2006Gasoline,ethers,benzene,toluene,n-hexane,methyl-cyclopentane,mtthyltert-butylether(MTBE)Anaerobicbiodegradationusingelectronacceptors(nitrate,FeIII,sulfate,bicarbonate)AerobicbiodegradationofMTBEcombinedwithanothercarbonsource(tertiarybuthanol,buthylformate,isopropanol,acetone,pyruvate)(mixedandpurecultures)CosteffectiveandfeasibleEnvironmentallyfriendlyprocessSimpler,lessexpensivealternativetochemicalandphysicalprocessesAerobicbiodegradationofMTBEisstillarareoccurrencebecausepfthedifficultyoforganismstobiodegradeMTBECulturecompositionandreactorconfigurationarekeyfactorsFayolleetal.
2003Linetal.
2007RaynalandPruden2008Wauletal.
2009PolychlorinatedbiphenylsAerobicbiofilmdevelopedusingmixedmicrobialcultureisolatedfromPCB-contaminatedsoil,acclimatizedtoPCBsbyfeedingthereactoralternatelywithbiphenylandPCBsAccumulationofchlorobenzoicacidsandchlorophenylglyoxylicacidintheenvironmentSayleretal.
1982Borjaetal.
2006Trichloroethylene(TCE)Anaerobically(TCEactsasanelectronacceptorinreductivedehalogenationbymethanotropicorganisms)Aerobicbiodegradationusinginducersforcometabolismandenzymeproduction(astoluene)andelectronacceptors(hydrogenperoxide)Anaerobicbioremediationwhereelectronacceptors,othersthanoxygenareneededtobeusedisapotentialadvantageDegradationefficiencyhigherthan80%forTCEconcentrationsupto700mg/LMixedculturesaregenerallypreferredTheratesofTCEremovaldependontheconditions,reactors,electronacceptorsTheeffectofbiostimulationofmultiplegroupsofbacteriaonTCEmetabolismnotentirelyknownWilsonandWilson1985Leeetal.
1998LyewandGuiot2003CutrightandMeza2007Shuklaetal.
2009TextileazodyesAnaerobictreatment(whiterotfungi,duetoextracellularenzymestheyproduce)Aerobically,byusingbacterialconsortia,actinomycetes,fungi,algaeInexpensive,eco-friendly,produceslessamountofsludgecomparativetophysico-chemicalmethodsAerobictreatmentissaferbecausetoxicintermediatesdonotappearTheeffectivenessofmicrobialdecolorizationdependsontheadaptabilityandtheactivityofselectedmicroorganismsIndividualbacteriastrainusuallycannotdegradeazodyescompletelyandtheintermediateproductsareoftencarcinogenicandmutagenicaromateaminesThedecolorizationratedependsontheoxidationpotentialoftheazodyesLopezetal.
2004SenanandAbraham2004Steffanetal.
2005Joshietal.
2008Sarataleetal.
200921DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksbioaccumulative,byapplyinglivingcells(Veglioetal.
1996;Zamboulisetal.
2002;Zamboulisetal.
2004)(Table14).
5.
Gasolineethers,methyltert-butylether(MTBE)Thecontaminationofmethyltert-butylether(MTBE)inwaterandespeciallyinundergroundwaterhasbecomeaproblemofgreatconcernallovertheworld(FiorenzaandRifai2003;Linetal.
2007;Zhongetal.
2007).
ThemassiveproductionofMTBE,aprimaryconstituentofreformulatedgasoline,combinedwithitsmobility,persistenceandtoxi-city,makesitanimportantpollutant.
SomestudiesofMTBEnaturalattenuationhaveattrib-utedmasslosstobiodegradation,whileothersattributedmasslosstodilutionanddispersion(FiorenzaandRifai2003).
MTBEdegradationisknowntobedifficultinnatu-ralenvironments(Martienssenetal.
2006).
Currently,therearefewreportsintheliteraturewhichhavedocumentedanaerobicdegradationofgasolineoxygenates(FiorenzaandRifai2003;Wauletal.
2009).
Inparallel,aerobicdegrada-tionofMTBEandsimilarcompundswasalsodemonstratedwithbothmixedandpurecultures(Zanardinietal.
2002;FiorenzeandRifai2003;Zhongetal.
2007)(Table14).
Itwasdemonstratedthatmixedculturesaregenerallymoreeffectivethanpurecultures.
Supplementswithreadilymeta-bolizableorganicsubstrateswereinvestigatedtoincreasethebiomassandenhancedegradationofMTBE(Martien-ssenetal.
2006;Zhongetal.
2007)(Table14).
6.
Trichloroethylene(TCE)Pollutantsincludinghaloalkenes(astrichloroethylene)enterintothebiosphereandcontaminatethesoilandground-waters.
Trichloroethyleneisoneofthemostimportantvola-tilechlorinatedorganiccompoundsusedassolventinvari-ousindustries(LyewandGoniat2003;Shuklaetal.
2009).
Itisgenerallyresistanttobiodegradation,asmicroorga-nismsdonotuseitasacarbonandenergysource(WilsonandWilson1985;Shuklaetal.
2009).
Aerobicbacterialculturesthatutilizevariouscarbonandenergysourcescanbeused(Ferhan2003).
Also,anae-robicbioremediationcanbeappliedforTCEbiodegrade-tionathigherTCEmetabolicratesundermixedelectronacceptorconditions(BoopathyandPeters2001).
ThemixedpopulationofmicroorganismswiththeabilitytodegradevariousorganiccompoundssuchasTCEmayfollowdiversemetabolicwaysandphysiologicalcharacteristicsdependingonworkingconditions(CutrughtandMeza2007).
7.
TextileazodyesAzodyesareusedfornumeroustextiledyestuff,producedbecauseoftheircost-effectivesynthesisandtheirstabilityandvarietyofcolorscomparedtonaturaldyes.
Also,azodyesareusedinpaper,food,leather,cosmetics,pharmaceu-ticalindustries(Changetal.
2001;Sarataleetal.
2009).
Bacteria,fungi,yeasts,actinomycetes,algaeareabletodegradeazodyes,byamechanismwhichinvolvesthere-ductivebreakingofazobonds.
Theprocesscanbecarriedoutinanaerobicconditionswiththehelpofazoreductaze.
Theresultingintermediatemetabolitescanbefurtherdeg-radedaerobicallyoranaerobically(Changetal.
2000;Rar-shettietal.
2007;Sarataleetal.
2009).
Microbialdegrada-tionofazodyesusuallystartsinanaerobicconditionswithareductivecleavageoftheazobond,followedbyanaero-bicstepnecessaryforthedegradationofthearomaticaminesformed(Steffanetal.
2005;Joshietal.
2008;Sara-taleetal.
2009)(Table14).
ENVIRONMENTALBIOTECHNOLOGYINPOLLUTIONDETECTIONANDMONITORINGEnvironmentalmonitoringdealswiththeassessmentofenvironmentalquality,essentiallybymeasuringasetofselectedparametersonaregularbasis.
Ingeneral,twomethods–physicochemicalandbiological–areavailableformeasuringandquantifyingtheextentofpollution(Jamil2001;LamandGray2003;Haggeretal.
2006;HartandMartínez2006;Conti2007).
Inthepastdecadesenvironmentalmonitoringprog-rammesconcentratedonthemeasurementofphysicalandchemicalvariables,whilebiologicalvariableswereoc-casionallyincorporated.
Physicochemicalmethodsinvolvetheuseofanalyticalequipment,havingaslimitationstheircost(becauseofthecomplexityofthesamplesandtheex-pertiseoftheoperatorsneededtoconducttheanalysis)andthelackofhazardandtoxicologicalinformation(CannonsandHarwood2004;Guetal.
2004).
Environmentalmonitoringisofgreatimportanceforitsprotection.
Theharmfuleffectoftoxicchemicalsonnaturalecosystemshasledtoanincreasingdemandforearly-war-ningsystemstodetectthosetoxicantsatverylowconcen-trationslevels(Durrieuetal.
2006).
Typicallycontaminantmonitoringinvolvestheregularandfrequentmeasurementofvariouschemicalsinwater,soil,sedimentandairoverafixedtimeperiod,e.
g.
,ayear.
Integrationofenvironmentalbiotechnologywithinfor-mationtechnologyhasrevolutionedthecapacitytomonitorandcontrolprocessesatmolecularlevels"inordertoachievereal-timeinformationandcomputationalanalysisincomplexenvironmentalsystems"(HasimandUjang2004).
Bioindicators/biomarkersMorerecently,environmentalmonitoringprogrammeshave,apartfromchemicalmeasurementsinphysicalcompart-ments,includedthedeterminationofcontaminantlevelsinbiota,aswellastheassessmentofvariousresponses/para-metersofbiological/ecologicalsystems.
Nowadays,tempo-ralandspatialchangesinselectedbiologicalsystems/para-meterscanandareusedtoreflectchangesinenvironmentalquality/conditionsthroughbiomonitoring(Marketetal.
2003;Conti2007;Lam2009).
Inthiscontext,someorganismsorcommunitiesmayreacttoanenvironmentaleffectbychangingameasurablebiologicalfunctionand/ortheirchemicalcomposition.
Thiswayitispossibletoinfersignificantenvironmentalchangeandtheirresponsesarereferredtoasbioindicators/bio-markers(NRC1987;Jamil2001;Marketetal.
2003;Conti2007).
Biomarkersarethususedinbiomonitoringprog-rammestogivebiologicalinformation,i.
e.
theeffectsofpollutantsonlivingorganisms.
Threemaintypesofindi-cationscanbeobtained:onexposure,effect,andsuscepti-bility.
Biomarkersthathavepotentialforuseinbiomonitoringare:-molecular(geneexpression,DNAintegrity)-biochemical(enzymatic,specificproteinsorindica-torcompounds)-histo-cytopathological(cytological,histopathologi-cal)-physiological-behaviouralUnfortunately,fieldapplicationofbiomarkersissubjecttovariousconstraints(e.
g.
,theavailabilityoflivingmate-rial)thatcanlimitdataacquisitionandpreventtheuseofmultivariatemethodsduringstatisticalanalysis.
Besides,theyshouldhavethefollowingattributes:besensitive(sothatitcanactasanearly-warning),specific(eithertoasin-glecompoundoraclassofcompounds),broadapplicable,easytouse,reliableandrobust,goodforqualitycontrol,abletobereadilytaughttothepersonnel,providethedataandinformationnecessary(BeliaeffandBurgeot2002;Lam2009).
22Environmentalbiotechnology.
MariaGavrilescuBiosensorsforenvironmentalmonitoringResearchonbiosensingtechniquesanddevicesforenviron-ment,togetherwiththatingeneticengineeringforsensorcelldevelopmenthaveexpandedinthelatesttime.
Environmentalbiosensorsareanalyticaldevicescom-posedofabiologicalsensingelementorbiomarker(en-zyme,receptorantibodyorDNA)inintimatecontactwithaphysicaltransducer(optical,massorelectrochemical),whichtogetherrelatetheconcentrationofananalytetoameasurableelectricalsignal(ReisandHartmeier1999;Rodríguez-Mozazetal.
2004).
Thebiosensorsexploitbiologicalspecificitytoproducesignalsthatcanbeusedtomeasurepollutionlevels.
Gene-rallyspeaking,biosensorisabroadtermthatreferstoanysystemthatdetectsthepresenceofasubstratebyuseofabiologicalcomponentwhichthenprovidesasignalthatcanbequantified.
Thesignalmaybeelectrical(Fig.
16),orintheformofadyethatchangescolour.
Theycompriseabio-logicalrecognitionelementsuchasanenzyme,antibodyorcellthatwillreactwiththematerialtobedetected.
Biosensorsbasedonacombinationofabiologicalsensingelementandanelectronicsignal-transducingele-mentthatofferhighselectivity,highsensitivity,short-res-ponsetime,portabilityandlowcost,areidealformoni-toringpollutantsinenvironment(LamandGray2003;Rod-ríguez-Mozazetal.
2006).
AsitcanbeseenfromTable15,variousbiologicalreactionscanbeusedforpollutantdetec-tion.
Biosensorsusebothprotein(enzyme,metal-bindingproteinandantibody)-basedandwhole-cell(naturalandgeneticallyengineeredmicroorganisms)-basedapproachesTable15,Infact,biosensorsrepresentasynergisticcombi-nationofbiotechnologyandmicroelectronics(VermaandSingh2005).
Theyhavefoundaplaceinmonitoringforevaluationofasampleanditsecologicaltoxicity.
Thesensingelementcanbeenzymes,antibodies(asinimmunosensors),DNA,ormicroorganisms;andthetransducermaybeelectroche-mical,optical,oracoustic(Biotech,2000)(Fig.
17).
Useofbiosensorsenablesrepeatedmeasurementswiththesamerecognitionelementandcanbeappliedtoawiderangeofenvironmentalpollutantsaswellasbiologicalpro-ducts(Fig.
16).
Thebiocatalyst(3)convertsthesubstratetoproduct.
Thisreactionisdeterminedbythetransducer(5)whichconvertsittoanelectricalsignal.
Theoutputfromthetransducerisamplified(6),processed(7)anddisplayed(8).
Whole-cellbiosensorsbasedeitheronchlorophyllfluo-rescenceorenzyme(phosphataseandesterase)inhibitionareconstructedforreal-timedetectionandon-linemoni-toring.
Ageneticallymodifiedyeastwasusedasbiosensortodetectendocrinedisruptorssuchasoestrogenor17-oestra-diol.
Althoughitwasinitiallydevelopedforuseinhumantherapeutics,thereisthepotentialuseinpollutiondetection(TuckerandFields2001;EvansandFurlong2003).
Avarietyofwhole-cell-basedbiosensorshasbeendeve-lopedusingnumerousnativeandrecombinantbiosensingcells.
Thesebiosensorsutilizingmicroorganismsaddressandovercomemanyoftheconcernswhicharosewithotherconventionalmethods,becausetheyareusuallycheapandAI11234567Fig.
16Detectionchainforabiosensor(abiologicalsensingelementandanelectronicalsignal-transducingelement).
1–substrate;2–membrane;3–immobilizedbiodetectorforrecognitionofasystemofbiologicaloriginlikeenzymes,antibodies,microorganisms;4–productresultedfromthereactionofsubstratewiththebiodetector;5–transducer(detectstheproductandconvertsitinanelectricalsignal);6–amplifier;7–interfaceforsignalprocessing;8–displayerofoutputsignal.
(AdaptedfromMulchandaniandRogers1998).
Table15Somebiosensorsfordetectionofenvironmentalpollution.
PrinciplemodeofdetectionPollutantsdetectedReferencesHydrothermallygrownZnOnanorod/nanotubeandmetalbindingpeptideHeavymetalsJiaetal.
2007Proteinbased:SyntheticphytochelatinsHeavymetals(Hg2+,Cd2+,Pb2+,Cu2+,Zn2+)Bontideanetal.
2003ChloroplastD1proteinHerbicidePiletskaetal.
2006EnzymesimmobilizedbyelectropolymerizationHeavymetals(Hg2+:anestablishedglucosebiosensorbasedonglucoseoxidaseimmobilizedinpoly-o-phenylendiamine)MalitesteandGuasceto2005EnzymaticreactionormicrobialmetabolismPesticides,phenols,halogenatedhydrocarbonsRiedeletal.
1991Rogers1995RecombinantbioluminescentbacteriaOrganiccompounds(inair,water,soil),heavymetalsHyunetal.
1993TescioneandBelfort1993Gu2005EnzymeinhibitionPesticides,heavymetals,herbicidesMartietal.
1993Botrèetal.
2000KuswandiandMascini2005PhotosyntheticactivityHerbicidesDurrieuetal.
2006Giardietal.
2007Wangetal.
2007Campàsetal.
2008MolecularlyimprintedmembranesPesticidesSchelleretal.
1997HauptandMosbach2000Uluda÷etal.
2007Vo-Dinh2007ImmunochemistryOrganiccompounds,pesticides,herbicides,PCBsChemnitiusetal.
1996Martyetal.
1998Ashleyetal.
200823DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBookseasytomaintainwhileofferingasensitiveresponsetothetoxicityofasample(Guetal.
2004).
Resultsshowthatthesedevicesaresensitivetoheavymetalsandpesticides(Durrieuetal.
2006;Mauritzetal.
2006).
Averyhighselectiveandsensitivesensorwasdeve-lopedasa"microchip"bycombiningbiologicalactivitywithnanowireelectronics(Cuietal.
2001),whichisabletodetectanelectriccurrentequivalenttothebindingofasin-glemolecule(EvansandFurlong2003).
Plantsarealsousedasbiologicalindicators,namelysensitiveandresistantwhiteclover(Trifoliumrepens)clones(asdescriptorsofbiomassreductionincropsspe-cies)andCentaureajacea(brownknapweed)asamodelspecies,theleavesofBrassicaoleraceavar.
acephala,usedasbiosampler,commonspeciesoftrees(wildolive,holmoak,whitepoplar)(Bargagli1998;Mertensetal.
2005;Madejonetal.
2006;Nalietal.
2006;Zelanoetal.
2006).
Invertebratespecies(targetandnon-targetinsects),crustaceanscanbealsousedforbiomonitoring(Lagadicetal.
2004;Raeymaekers2006).
Biosensorscanbeappliedfor:-toxicityscreeningofsamplesusingbioluminescenceorfluorescence(Rabbowetal.
2002;Weitzetal.
2002;Guetal.
2004;Rodriguez-Mozazetal.
2004)-waterqualitymonitoring(Ramsden1999;Ashboltetal.
2001;CannonsandHarwood2004;Starodubetal.
2005;Mauritzetal.
2006;Mwinyihijaetal.
2006)-atmosphericqualitybiomonitoring(Nalietal.
2006;Zelanoetal.
2006)-soil-contaminationbiomonitoring(DoranandParkin1994;Tom-Petersenetal.
2003;Guetal.
2004;Ahnetal.
2005;Tarazonaetal.
2005).
ENVIRONMENTALBIOTECHNOLOGYFORPOLLUTIONPREVENTIONANDCLEANERPRODUCTIONRoleofbiotechnologyinintegratedenvironmentalprotectionapproachBiotechnologyisregardedasthemotorforintegratedenvi-ronmentalprotection.
Complementarytopollutioncontrolwhichstrugglesforthetailendoftheprocessesandmana-gespollutiononceithasbeengenerated,pollutionpreven-tionworkstostoppollutionatitssourcebyapplyinganum-berofpractices,suchas:-usingmoreefficientrawmaterials-substitutinglessharmfulsubstancesforhazardousmaterials-eliminatingtoxicsubstancesfromproductionprocess-changingprocesses-othersThestrengtheningofconcernsfortheglobalenviron-mentisresultinginincreasedpressureforeconomicalbran-ches(industry,agriculture,transport,market)tofocusonpollutionpreventionratherthanend-of-pipecleanup.
Fromanoverallmaterialconsumptionperspective,excessivequantitiesofwasteinsocietyresultfrominefficientproduc-tionprocesses(ontheindustrialside),andunsustainableconsumptionpatternscombinedwithlowsustainabilityofgoods(ontheconsumerside)(Cheremisinoff2003;Gavri-lescu2004b;GavrilescuandNicu2005).
Modernenviron-mentalprotectionstartswiththepreventionofharmfulsub-stancespriortoandduringindustrialproductionprocesses.
DobleandKruthiventi(2007)havecharacterizedanidealprocessasfollows:anidealprocessissimple,requiresonestep,issafe,usesrenewableresources,isenvironmentallyacceptable,hastotalyield,produceszerowaste,isatom-efficient,andconsistsofsimpleseparationsteps(Fig.
18).
Sincebiotechnologycancontributetotheeliminationofhazardouspollutantsattheirsourcebeforetheyentertheenvironment,industrialandenvironmentalbiotechnology-biotech'sthirdwave-usesbiologicalprocessestomakeindustriallyusefulproductsinamoreefficient,environ-mentallyfriendlyway,bycuttingwastebyproducts,airemissions,energyconsumptionandtoxicchemicalsinseve-ralindustries(Bull1995;Olguin1999;GavrilescuandChisti2005).
Althoughenvironmentalbiotechnologyhasprimarilyfocusedonthedevelopmentoftechnologiestotreataque-ous,solidandgaseouswastesatpresent,thebasicinforma-tiononhow"biotechnologycanhandlethesewasteshasEnvironmentalbiosensorsBiologicalrecognitionelementPhysicaltransducerENZYMEScatalytictransformationofpollutantsmodificationofenzymaticactivitybypollutantsspecificinhibitionofenzymaticactivitybypollutantMICROORGANISMSinhibitionofcellularrespirationbypollutantpromotorrecognitionbyspecificpollutantfollowedbygeneexpression,enzymesynthesis,catalyticactivityidentificationandenumerationofmicroorganismsbyimmunocaptureorDNAsequencehybridizationsensormethodANTIBODIEScompoundorclassspecificaffinitytowardthepollutantELECTROCHEMICALpotentiometricamperometricpotentiometricstrippinganalysisOPTICALELECTRONIClight-addressablepotentiometricsensorsurfaceplasmonresonanceOPTICALabsorbanceluminescencefluorescencetotalreflectancefluorescenceACOUSTICquartzcrystalmicrobalancesurfaceacousticwavesurfacetransversewaveFig.
17Structureofenvironmentalbiosensors.
(AdaptedfromMulchandaniandRogers1998;Rodriguez-Mozazetal.
2004,2006).
24Environmentalbiotechnology.
MariaGavrilescubeengainedandthefocalpointisnowontheimplementa-tionoftheseprocessesasBestAvailableTechnologyNotEntailingExcessiveCosts(BATNEEC)intheframeworkofstrictandtransparentenvironmentallegislation"(GrommenandVerstraete2002).
Theapplicationofbiotechnologyasanenvironmentallyfriendlyalternativeinconventionalmanufacturingprovestobeveryusefulforpollutionpreventionthroughsourcere-duction,wasteminimization,recyclingandreuse.
Inmostcases,thisresultsinlowerproductioncosts,lesspollutionandresourceconservationandmaybeconsideredastaskforceofbiotechnologyforsustainabilityinindustrialdeve-lopment.
Themainareasinwhichbiotechnologycontribu-tionmayberelevantfallintothreebroadcategories(EvansandFurlong2003):processchanges,biologicalcontrol,bio-substitutions.
Becausebiotechnologicalprocesses,oncesetupareconsideredcheaperthantraditionalmethods,changesinproductionprocesseswillnotonlycontributetoenviron-mentalprotection,butalsohelpcompaniessavemoneyandcontinuouslyimprovetheirpublicimage(Olguin1999;EvansandFurlong2003;GavrilescuandNicu2005;Willkeetal.
2006).
Inthecontextofpollutionpreventionpractices,biotech-nologycancontributetosubstitutemultistepchemicalpro-cesseswithaone-stepbiologicalprocessusinggeneticallymodifiedorganisms(GMOs)aswell(Reisetal.
2006).
Thisactionshouldhaveotherbeneficialresultsbecauselanddis-posalofhazardouswaste,wastewaterloadings,airemis-sionsandproductioncostsaregreatlyreduced.
Also,pre-ventionpracticesassistedbyenvironmentalbiotechnologymayproveinstrumentalinpermittingproceduralchanges.
ProcessmodificationandproductinnovationThetechniquesofmodernmolecularbiologyareappliedintheindustryandenvironmenttoimproveefficiencyanddiminishtheenvironmentalimpact.
Processinnovation,thedevelopmentofnewbiologicalprocesses,andthemodifica-tionorreplacementofexistingprocessesbytheintroduc-tionofbiologicalstepsbasedonmicrobialorenzymeactionareincreasinglybeingusedinindustrialoperationsasanimportantpotentialareaofprimarypollutionprevention(Olguin1999;Gavrilescu2004b;GavrilescuandNicu2005)(Table16).
Similarly,theuseofnewbiofuelsandbiomaterialsthathavelittleornoenvironmentalimpactisexpandingrapidly.
Biodegradation,biotransformationandbiocatalysisarethreeprocessesthatoccurasaresultofmicrobialmeta-bolism.
Amanufacturerusingmicrobialmetabolismissaidtobeconductingabiotransformationortobeusingbiocata-lysis.
Insomecases,theseinterestscanoverlap(Fig.
19).
Biotransformationinvolvesmodificationsoforganicmoleculesintoproductsofdefinedstructure,inthepresenceofmicrobe,plantoranimalcellsorenzymes.
Biotransformationsbymicrobesfurnishbothregio-andstereospecificproducts,thereactionscanberunundergen-tleandcontrolledconditionsandnewproductscanbebio-synthesized.
AsurveycarriedoutbytheFraunhoferInstituteforSystemsandInnovationResearchinKarlsruheonbehalfoftheMinistryoftheEnvironmentinStuttgartrevealedthatthepotentialofproduct-integratedenvironmentalbiotech-nologyisenormous:reducedenvironmentalpollution(70%),reducedprocesscosts(64%)andimprovedproductquality(22%).
Initsspecificuseinproductionandproductprocessing,biotechnologyhelpssaveenergyandrawmaterialsintheproductionoftextiles,food,washingdetergents,pharma-ceuticals,bymeansofgeneticallymodifiedenzymes.
Theyalsohelpavoidundesiredwasteproductsduringproduction.
Biotechnologicalprocessesgenerallyoperateundergentleconditions,usebiodegradablerawmaterialsandinter-mediatesandwaterisusuallythesolvent.
Asaresultofhighenzymaticspecificity,biologicalsynthesiscanleadtoincreasedyieldsandlessby-products,thussavingadditionalIdealprocessRenewableresourcesEnvironmentallyfriendly100%yieldZerowasteAtom-efficientSimpleseparationMinimumnumberofsteps(onestep)SafeFig.
18Criteriaforanidealproductionprocess.
BiodegradationBiotransformationBiocatalysisNewpathwaysNewenzymesImprovedbiodegradabilityWasteminimizationProcessdevelopmentNewreactionsNewtargetsFeasibilityofdesiredreactionsModifiedsubstraterangeReactionmechanismsMathematicalandphysicaldescriptionFig.
19Interdependenceofthethreemainapplicationareasofenzymecatalysis.
(Paralesetal.
2002).
25DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksTable16Industrialprocessesorproductschangedbyestablishingbiotechnologicalsteps.
ProcessorproductConventionalmanufacturingprocessNewindustrialbiotechprocessCostsandenvironmentalbenefitsDetergentPhosphatesaddedasabrighteningandcleaningagentsGeneticallyenhancedmicrobesorfungiengineeredtomakeenzymesAdditionofbiotechnologyenzymesasbrighteningandcleaningagents:ProteasesremoveproteinstainsLipasesremovegreasestainsAmylasesremovestarchstainsEliminationofwaterpollutionfromphosphatesBrighter,cleanerclotheswithlowertemperaturewashwaterEnergysavingsBreadPotassiumbromate,asuspectedcancer-causingagentatcertainlevels,addedasapreservativeandadoughstrengtheningagentMicroorganismsgeneticallyenhancedtoproducebakingenzymes(directedevolutionandrecombinantDNA)Additionofbiotechnologyenzymesto:enhancerisingstrengthendoughprolongfreshnessHigh-qualitybreadLongershelflifeNopotassiumbromatePolyesterbeddingPolyesterproducedchemicallyfrompetroleumfeedstockExistingbacillusmicrobeusedtofermentcornsugartolacticacid;lacticacidconvertedtoabiodegradablepolymerbyheating;polymermadeintoplasticproductsandpolyesterBiotechpolyester(PLA)producedfromcornstarchfeedstockPLApolyesterdoesnotharborbodyodorlikeotherfibersBiodegradableNotmadefrompetroleumDoesnotgiveofftoxicsmokeifburnedPlasticsPetroleumisusedasfeedstock,crackedinmonomersPolymerizationincludeseveralsteps,polymersareprocessedfurtherintoplasticsUseplantsugars,lignocellulosicbiomass,straworcornresiduesTheprocessharnessescarbonstoredinplantstocreatethePLApolymerPLAplasticsarebiodegradableUpto80%reductioninpetroleumusageAntibioticsChlorinatedsolventsandhazardouschemicalsusedtoproduceantibioticsthroughchemicalsynthesisGeneticallyenhancedorganismdevelopedtoproducethekeyintermediateofcertainantibiotics(recombinantDNA)One-stepbiologicalprocessusesdirectfermentationtoproduceantibioticintermediate65%reductioninenergyconsumptionOverallcostsavingsReducedenvironmentalimpactReducesgreenhousegasemissionsVitaminB2ProductionstartswithglucosefollowedbysixchemicalstepsusinghazardouschemicalsandgeneratinghazardouswasteToxicchemicals,suchasaniline,usedinchemicalsynthesisprocessGeneticallyenhancedmicrobedevelopedtoproducevitaminB2(directedevolution)One-stepfermentationprocessusesvegetableoilandglucoseasafeedstockCruderiboflavinisproduceddirectlyfromglucosewithageneticallymodifiedstrainofBacillussubtilis(agram-positivebacterium)A10-stepchemicalprocesswasreplacedbyasinglefermentationprocess,eliminatingtheuseofnumeroustoxicchemicalsandreducingtheacidityofthewastewaterproducedBiologicallyproducedwithoutchemicalsLesschemicallyintensiveBasedoftheuseonarenewablerawmaterial(glucose)Reducedlanddisposalofhazardouswaste,waste-to-waterdischargeby66%,airemissionsby50%,andcostsby50%TextilefinishingStonewashedBlueJeansTextilebleachingbyusinghydrogenperoxideChemicaltreatmentusinghotsodiumhydroxidetoremoveimpuritiesOpen-pitminingofpumicefabricwashedwithcrushedpumicestoneand/oracidtoscuffitTextileenzymesproducedbygeneticallyenhancedmicrobe(extremophilesandrecombinantDNA)EnzymesusedinhighlyspecializedtextilefinishingprocessFabricwashedwithbiotechnologyenzyme(cellulase)tofadeandsoftenjeansorkhakis(biostoning)LessminingSofterfabricSuperiorproductssuchasmoredurablecarpeting,lightweightbulletproofmaterial,strongersilkUpto18%reductionoftheamountofbleachingagentsandwaterReducedenergyconsumptionLowercostReducedenvironmentalimpactPaperbleachingDe-inkingrecycledpaperWoodchipsboiledinaharshchemicalsolutionthenbleachedwithchlorinetoyieldpulpforpapermakingWood-bleachingenzymesproducedbygeneticallyenhancedmicrobes(recombinantDNA)EnzymesselectivelydegradeligninandbreakdownwoodcellwallsduringpulpingReducesuseofchlorinebleachandreducestoxicdioxinintheenvironmentUpto15%reductionofchlorineinwastewaterUpto40%reductionofenergyusageCostsavingsduetolowerenergyandchemicalcostsFuelbasedonethanolFoodandfeedgrainsfermentedintoethanol(atechnologythatisthousandsofyearsold)Geneticallyenhancedorganismdevelopedtoproduceenzymesthatconvertagriculturalwastesintofermentablesugars(directedevolution,geneshuffling)Cellulaseenzymetechnologycanconvertcellulosetoitsconstituentsugars,whicharethenfermentedanddistilledtomakebioethanol(andotherchemicalsandproductsifdesired)Cellulaseenzymetechnologyallowsconversionofcropresidues(stems,leaves,straw,andhulls)tosugarsthatarethenconvertedtoethanolRenewablefeedstockIncreasesdomesticenergyproductionReducesgreenhousegasemissionsTheuseofcropresidueratherthanthegraincropitselfallowsforsignificantreductionsinenergyinputsandpollutionrelatedtobioethanolproductionBioethanolfromcellulosegenerates8to10timesasmuchnetenergyasisrequiredforitsproductionCosmeticsIsopropylmyristaleproduction,asmoisturingagent;Largeenergyrequirementprocess(hightemperatureandpressure);TheproductsneedsfurtherrefinementEnzyme-basedesterificationprocessReducingtheenvironmentalimpactbyderivingacleaner,odorfreeproductHighyieldsLowerenergyrequirementLesswastefordisposal26Environmentalbiotechnology.
MariaGavrilescucostsforfurtherpurification.
Biotechnologicalandgeneticengineeringmethodsarealsoabletoreducetheenviron-mentalloadinthefieldofrenewablerawmaterials("meta-bolicdesign").
Thepracticehasdemonstratedthatbiotechnologycan-notsolvealltheproblemsassociatedwithpollutionpreven-tionandcleanerproduction,butithasprovenitselftobeapowerfulandflexiblemeansinarangeofindustrysectors(pulpandpaper,finechemicals,plastics,mining,energy)(Table16).
Biotechnologicalprocessescancontributetosustaina-bility,providedtheyreplacechemicalproductionmethods.
PulpandpaperindustryPulpandpaperindustryhasachievedanimpressiverecordinbecominganenvironmentallycleanerindustry.
Alongtermobjectivereferstothegeneticengineeringthatcanex-ploititsabilitytorevolutionizetheforestssothattreeswithfibershavingoptimalpapermakingpropertieswillgrow(Pullmanetal.
1998).
Fungiareusedforlignindegradationduringbiopulping,thetreatmentofwoodchipsandotherlignocellulosicmaterialspriortothermomechanicalpulping.
Thisisawaytoreducetherequirementsforchemicalsandenergy,whichwouldalsodecreasetheenvironmentalim-pactofpulpingprocess.
In2004,twoindustriessponsoredconsortiaand22pulpandpaperandrelatedcompaniesofU.
S.
Ahavereportedthetechnicalandeconomicfeasibilityofbiopulping(Shuklaetal.
2004).
Also,thebiobleachingofpulpwithenzymes(laccase/mediator,xylanases,manga-neseperoxidase,lignolyticenzymes)hasgainedsignificantinterestbecauseofitsselectivityandthepossibilitytosaveupto25%ofchlorinecontainingbleachingchemicalsortoestablishachlorine-freebleachingprocess(Lemaetal.
1999;Balakshinetal.
2001;Sasakietal.
2001;ChakarandRagauskas2004;Shuklaetal.
2004).
Also,paperrecyclingtriestochangefromthechemical-baseddeinkingprocessthatcurrentlyusessodiumhydroxideandavarietyoffloc-culants,dispersants,andsurfactantstowardanalternativewhichisbasedonmicrobialenzymes.
Asidefromthat,thein-plantwastewaterbiotreatmentcouldremovedissolvedandcolloidalorganicmaterialandmetalionsinordertopreventdepositandslimeproblems(Ah-Youetal.
2000;Gavrilescuetal.
2008).
Enzymeshavefoundwideapplicationsinthetextileindustryforimprovingproductionmethodsandfabricfini-shing,forexampletoremovelubricants,whichareintro-ducedinnaturalfibersproductiontopreventsnaggingandreducethreadbreakageduringspinning(Novozymes2001;EvansandFurlong2003).
Theprocessofbioscouringforwoolandcottonwhichusesenzymestendstoreplacethetraditionalchemicaltreatment.
TechnicalsupportwasofferedtoanIndiantextilemillinordertoapplyabiolo-gicalscouringprocessforremovalofnon-cellulosiccom-ponentsandotherimpuritiesfoundinnativecotton,whichledtoa90%reductionofchemicals(Novozymes2001).
Biopolishinginvolvesenzymesinshearingoffcottonmicrofibrestoimprovematerialsoftness.
Acurrentapplicationofbiotechnologyisthebleachingofdenimfabrics.
Theuseofbiotechnologicalproceduresemployingenzymesreducesenergyconsumption,aswellaswastewaterpollution,becauseenzymesremovetheresidualbleachfromtextiles.
Intheleatherindustry,theuseofenzymesnotonlyleadstomoreconsistentquality,betterfinalcolor,butalsoconsiderablyreducesVOCandsurfactants.
Microbialdesulphurizationofcoalandoilisanimpor-tantsectorwhereenvironmentalbiotechnologyisinvolved.
Theuseofmicroorganismsmayincreasethesulphuroxida-tionrateinacertainbioreactorconfiguration.
Thedevelop-mentofbiocatalyticdesulphurizationprocessandbioreac-torsisanimportantadvanceinenvironmentalfriendlybio-technologicalprocesses(Monticello2000;Lietal.
2005;Killbane2006).
BiofuelsProductionofbioethanol,biodiesel,biogasusingagricultu-ralsubstrates,wastes(forestry,landfill,municipal,indus-trial,farming)vegetableoils(soybean,canola,sunflower)byenzymaticconversionordigestionisalreadyinforceasaresultofexcellentresearchanddevelopmentcapacitiesinindustry,universitiesandotherlaboratoriesinterestedinapplicationofbiotechnologyforenergysaving,resourceconservation,wastemanagementandenvironmentalprotec-tion(Ah-Youetal.
2000;DaleandKim2006;Willkeetal.
2006).
Anumberofdifferentapplicationshavedevelopedtheideaofanaerobicdigestionformethaneproduction,notablyinthewastemanagement,sewagetreatment,agriculturalandfoodprocessingindustries.
Biogasisamethane-richgasresultingfromtheactivitiesofanaerobicbacteria,res-ponsibleforthebreakdownofcomplexorganicmolecules,asshowninFig.
20.
Itiscombustible,withanenergyvaluetypicallyintherangeof21–28MJ/m3(Dobleetal.
2004).
ChemicalsBulkchemicalsynthesisfromrenewableresourcesisstilllimited,butitisconfirmedthatthebioconversionofrenew-ablebiomassfeedstocksuchasagriculturalandwoodwastesintoethanolorotherfuelscanleadtomajorenviron-mentalandeconomicbenefits(GavrilescuandChisti2005;Willkeetal.
2006;Chisti2007).
ThecompanyDuPontin-tendstoproduceanimportantvolumeofitsproducts(e.
g.
plastics)fromrenewableresources,startingwith2010(Willkeetal.
2006).
Currently,traditionalmethodsarestillusedinfineche-micalindustries,whichcontinuetogeneratesevereenviron-mentalproblems.
AnEco-EfficiencyAnalysis,performedbySaling(2005)withtheaimtoharmonizeeconomicalandecologi-calfeaturesofvitaminB2fabricationdemonstratedwhichvitaminB2productionprocess(biotechnologicalandche-mical)isthemosteco-efficient.
Thebiotechnologicalpro-cesswasmoreeco-efficient,sinceithadtheloweroverallenvironmentalimpactandthelowercost.
Progressinbio-andgeneticengineeringhasshownthatvitaminB2(riboflavin)canbeproducedusingbiotechnolo-gicaltools,atcostsreducedby50%,andalsoinmoreenvi-ronmentally-soundways(BIO–PRO2008).
Aonestep,purelyfermentativeprocessreplacedthetraditionalmethod,insixsteps.
Theremarkablepotentialofmicrobesinthetransforma-tionofsteroidsthroughhydroxylationledtothedevelop-mentofantiarthriticsteroids.
Variousstrainsweretested,suchas:Rhizopusarrhizus(DuttaandSamantha1997),BiowasteHydrolysisHydrolyticbacteriaAcidogenesisAcetogensAcetogenesisHydrogenotrophesAcetoclastsMethanogenesisMethaneandcarbondioxideFig.
20Schematicrepresentationofthereactionpathwaysforbiowastemethanisation.
(AdaptedformBlonskajaandVaalu2006).
27DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksSyncephalastrumracemosum(SenandSamantha1981).
Newsemisyntheticpenicillinswereproducedandusedinchemotherapy,6-aminopenicillanicacid(6-APA)beingthekeyintermediateusedforthesynthesisofthesepeni-cillins.
Thebiologicalsynthesisof6-APAis20%cheaperthanchemicalsynthesis.
InadditionitmeetssomecriteriaforanidealprocessshowninFig.
18.
DetergentenzymesEnzymeshavebeenusedindetergentssincethe1960s.
Theuseofenzymesindetergentsprovidesconsumerswithwellprovenbenefits.
Detergentenzymespresentnorisktocon-sumers,ortoemployeesinenzymeproduction.
Enzymescanreducetheenvironmentalloadofdeter-gentproductssincetheymeetthefollowingcriteria(Fig.
18):xSaveenergybyenablingalowerwashtemperaturexPartlyreplaceother,oftenlessdesirable,chemicalsindetergentsxArebiodegradable,leavingnoharmfulresiduesxHavenonegativeenvironmentalimpactonsewagetreatmentprocessesxDonotpresentarisktoaquaticlifeTheuseofenzymes,togetherwithdevelopmentsindetergents,hasreducedwashingtemperaturesto30-40deg-rees,temperatureswhichareexpectedtobereducedevenfurther.
Scarcityofwaterandincreasingoilandwaterpricesareexpectedtofurtherthedevelopment.
CalculationsshowthatinDenmarkwithfivemillioninhabitants,are-ductionofwashtemperaturefrom60to40°Cwouldleadtoanenergysavingequivalenttoapprox.
40,000tonnesofcoalayear.
Bycomparison,lessthan300tonnesofcoalayearwouldbeneededtoproducetheenzymesthatenablelowerwashtemperature.
Althoughtheirbiotechnologicalproductionismaterialandenergyconsuming,theresultsincleanlinessobtainedwithenzyme-containingdetergentsarefarsuperiortothoseobtainedwithtraditionalphosphate-containingwashingdetergents.
Also,duetotheirspecificcleansingeffect,en-zymesreducetheamountofwashingdetergentsandadditives,thewashingtemperatureandenergyconsumption.
Somecompaniesusedwild-typeandnaturalenzymes,butalsogeneticallymodifiedenzymesascomponentsofwashingdetergents.
BioplasticsPlasticsproductionfromsyntheticpolymersconsumesvastquantitiesofnon-renewableresources,whiletheyrepresentamajorenvironmentalproblemastheyarenon-biodegra-dable(Stevens2002;Chiellinietal.
2003;Reddyetal.
2003).
Theproductionofnewbiomaterialslikebioplasticsbasedonsugars,oils,proteins,fibersandothernaturalsub-stancesextractedfromplantsavoidstheuseofnon-renew-ableresourceslikefossilfuels,withlessenergy,fewerresources,andreducingglobalgreenhouse-gasesemissions.
Microbescanbeinducedtoproduceenzymesneededtoconvertplantandvegetablematerialsintobuildingblocksforbiodegradableplastics(Luengoetal.
2003;Reddyetal.
2003;Moldesetal.
2004).
Bothbioplasticproductionfromorganicwastematerialandplasticreductionwiththecontributionofenzymeshaveattainedtwoenvironmentalobjectives:-thereleaseofplasticproductionfromfossilfuels-biodegradationoftheplasticmaterialtoreducewaste,especiallyinfoodpackagingandfield-coveringplasticThereportreleasedbyOECD(2001)assessedthewide-spreadingofindustrialbiotechnologybasedon21com-paniescasestudydata,includingpharmaceutical,chemical,paper,textilesandenergysectors.
Thisreporthasshownthatindustrialbiotechnologyledtocleanerproductionandproducts,havinganenvironmentallysoundprofoundcha-racter.
ReducingtheenvironmentalimpactofagriculturalpesticidesTheexcessiveuseofchemicalherbicides,pesticides,fungi-cidesandfertilizersasanintegralpartofintensiveagri-culturecausedenvironmentalhazardsasaresultoflowbio-degradability.
Theuseofgeneticallymodifiedplantvarietieswhichareresistanttoinsectsand/ordiseasesmayconsiderablydiminishtheuseofpesticides.
Biopesticides(alsoknownasbiologicalpesticides)arederivedfromnaturalmaterials(animals,plants,bacteria,minerals)andareconsideredlesstoxicthanconventionalpesticides.
USEPA(2008)indicatesthatattheendof2001therewereapproximately195registeredbiopesticideactiveingredientsand780products(MennandHall1999).
Theycanbeclassifiedas(Fraser2005;USEPA2008):-microbialpesticides,containingamicroorganism(bacterium,fungus,virusorprotozoa)asactiveingre-dients(Table17).
-plant-incorporatedprotectants,whichmeansthattheactivepesticideisproducedbyplantsfromgeneticmaterialsaddedtotheplant.
-biochemicalpesticides,includesubstanceswhichTable17Organismgeneratingbiopesticidesandtheircontroltargets(MCD2008).
TargetOrganismExampleBacteriaBacillusthuringiensisBacillussphaericusPaenibacilluspopillaeSerratiaentomophilaVirusesnuclearpolyhedrosisvirusesgranulosisvirusesnon-occludedbaculovirusesFungiBeauveriaspp.
MetarhiziumEntomophagaZoopthoraPaecilomycesfumosoroseusNornuraeaLecanicilliumlecaniiProtozoaNosemaThelohaniaVairimorphaEntomopathogenicnematodesSteinernemaspp.
Heterorhabditidspp.
InsectsOtherspheromonesparasitoidspredatorsmicrobialbyproductsWeedcontrolFungiColletotrichumgloeosporioidesChondrostereumpurpureumCylindrobasidiumlaeveXanthomonascampestrisFungiAmpelomycesquisqualisCandidaspp.
ClonostachysroseaCompetitiveinnoculantsConiothyriumminitansPseudozymaflocculosaTrichodermaspp.
PlantdiseasecontrolComposts,soilinnoculantsBacillumpumilusBacillussubtilisPseudomonasspp.
StreptomycesgriseoviridisBurkholderiacepaciaNematodetrappingfungiMyrotheciumverrucariaPaecilomyceslilacinusBacteriaBacillusfirmusPasteruriapenetransNematicidesMolluscpanasiticnematodePhasmarhabitishermaphrodita28Environmentalbiotechnology.
MariaGavrilescucontrolpestsbynontoxicmechanismsBiopesticidesareofteneffectiveinverysmallquantitiesandoftendecomposequickly,andtheexposureislow(Boyetchkoetal.
1999),sothattheirusecouldresultinreducedrisktohumanhealthandtheenvironment.
Bio-pesticidesexhibitoneormoreofthefollowingcharacteris-tics(Fraser2005):lowtoxicitytonontargetorganisms,lowpotentialtocontaminateenvironmentalcomponentsandre-sources,lowrisktohumanhealth.
Examplesofbiopesti-cidesandtheirtargetsaregiveninTable17(MCD2008).
Theuseofgeneticallymodifiedplantvarietiesthatareresistanttoinsectsand/ordiseasesmayconsiderablydimi-nishtheuseofpesticides.
Insect-protectedcropsallowforlesspotentialexposureoffarmersandgroundwatertoche-micalresidues.
IntegrationofnanotechnologywithenvironmentalbiotechnologyThenanoscalebioscienceandbiotechnologyintegrationleadstopotentialandactualbreakthroughsinareassuchasmaterialsandmanufacturing,medicine,healthcare,energy,environment,chemicals,agriculture,informationtechno-logyetc.
(HasimandUjiang2004).
Theemergenceofnano-biotechnologyandtheincorporationoflivingmicroorga-nismsinbiomicroelectronicdevicesarerevolutionizinginterdisciplinaryopportunitiesformicrobiologistsandbio-technologiststoparticipateinunderstandingmicrobialprocessesinandfromtheenvironment.
Moreover,itoffersrevolutionaryperspectivestodevelopandexploitthesepro-cessesincompletelynewways.
"Biomedicalandbiotechnologicalapplicationsofnano-particleshavebeenofspecialrecentresearchanddevelop-mentinterest,withpotentialapplicationsthatincludeuseofnanoparticlesasdrug(orDNA)deliveryvehicles,andascomponentsinmedicaldiagnostickits,biosensorsandmembranesforbioseparations"(KohliandMartin2005).
Carbonnanotubes,anotherexcitingareaofresearchanddevelopmentinthenano-world,canbecoatedwithreac-tionspecificbiocatalystsandotherproteinsforspecializedapplications,makingthemevenmoreenvironmentallyfriendlyandeconomicallyattractive.
Scientistshavedeve-lopedversatilemethodsfortargetingcarbonnanotubestospecifictypesofcellsthatcouldspurthedevelopmentofnewanticanceragentsthatrelyontheuniquephysicalcha-racteristicsofcarbonnanotubes.
Suchbio-nano-systemsleadtoanewgenerationofintegratedsystemsthatcombineuniquepropertiesofthecarbonnanotube(CNT)withbiolo-gicalrecognitioncapabilities(Alivisatos2004;GaoandKong2004;WongShiKametal.
2005).
Though,highoperativecosts,expenditureforresearchanddevelopmentaswellasinvestmentstilllimittheestab-lishmentofbiotechnologicalprocesses.
BioenergyfrombiomassUsingbiomasstogenerateenergyhaspositiveenvironmen-talimplicationsandcreatesagreatpotentialtocontributeconsiderablymoretotherenewableenergysector,particu-larlywhenconvertedtomodernenergycarrierssuchaselectricityandliquidandgaseousfuels(IBEP2006;Gavri-lescu2008).
Bytheyear2120,3.
6%ofelectricpowerand6-7%ofthetotalenergywillcomefromrenewableresources(Lakoetal.
2008).
BiorefiningThebiorefiningconceptisananalogueoftoday'spetroleumrefineriesproducingmultiplefuelsandprodcutsfrompetro-leum.
Bycombiningchemistry,biotechnology,engineeringandsystemapproach,biorefinerycouldproducefood,ferti-lizers,industrialchemicals,fuels,powerfrombiomass(Gravitisetal.
1998;KammandKamm2004).
ENVIRONMENTALBIOTECHNOLOGYANDECO-EFFICIENCYEco-efficiencyanalysiscanoffercomprehensibleinforma-tionforalargenumberofapplicationsconcerningmultifac-torialproblemswithinrelativelyshorttimesandatrela-tivelylowcost,sinceitwasdiscernedasanimportantassessmentmethodforresearchanddevelopment,produc-tionandmarketing(Saling2005).
Thereisnodoubtthatenvironmentalbiotechnologyhasagreatpotentialtobeanecologicallybeneficialandatthesametimeeconomicallyprofitableinmanyareas.
Environ-mentalchallengesincreasinglyaffectthecompetitiveness,notonlyintermsofclean-upandpollution-controlcostsbutalsointhemarketplace.
WorldBusinessCouncilforSustainableDevelopment(WBCSD)developedeco-efficiencyasawayforanopera-tionalsustainabledevelopmentdrivingforcefromabusi-nessperspective(WBCDS2000).
Eco-efficiencyismoreandmorebecomingtheheartofsuccessintheeconomicworldasawaytomaximizeefficiency,whileminimizingtheimpactontheenvironment.
Itisachievedinpracticebymeansofthreekeyobjectivesthatregardincreasingproductorservicevalue,optimizingtheuseofresources,reducingenvironmentalimpact(GabrielandBraune2005;Gavri-lescuandChisti2005;Bidoki2006).
Becauseoftheoppor-tunityforcostsavingsassociatedwitheachoftheseobjec-tives,eco-efficienttechnologiesandpracticesdemonstratethateco-efficiencystimulatesproductivityandinnovation,increasescompetitivenessandimprovesenvironmentalper-formancethatmeanscreatingmorevaluewithlessimpact(Bidoki2006).
Biotechnology–ingeneral,andenviron-mentalbiotechnology–inparticularcanbeconsideredoneofthemostusefulmeanstoattaineco-efficiencyandfordecision-makingbecauseoffersanumberofpracticalbene-fits,illustratedin(Table18)(Wall-Markowskietal.
2004;Saling2005).
Forexample,minimizationofpesticideuseisoneofthemainpracticesforsustainablefarming,butalsoaproactiveconsiderationforthefutureofaneco-efficientagriculture,asanillustrationforoneelementofeco-effici-ency:reducetoxicdispersion.
Also,eco-efficiencygoeshand-in-handwithpollutionpreventionandeco-designpracticesthatessentiallyinvolvereductioninthematerialandenergyflowintensity,improvedrecyclability,maxi-mumuseofrenewableresourcesinordertoensuresus-tainableproductionandconsumption(Olguin1999;WBCSD2000;Gavrilescu2004b;GavrilescuandNicu2005).
AstudyofOECDemphasizesthatgreatindustrialcom-paniesarebecomingawareoftheimportanceofsustainabledevelopmentandofthegreatpotentialofbiotechnologythatcanhelpthemimprovetheenvironmentalfriendlinessofindustrialactivitiesandlowerbothcapitalexpenditureandoperatingcosts,operatingasanenvironmentally-soundbasisforeconomyandsociety(OECD2001).
SomecasestudiespresentedbyEuropaBioasaresultofTable18Someofthepracticalbenefitsoftheeco-efficiencybybiotechnology.
Eco-efficiencypracticalbenefitMeanstoachievereducedcoststhroughmoreefficientuseofenergyandmaterialsreducedriskandliabilitybydesigningouttheneedfortoxicsubstancesincreasedrevenuebydevelopinginnovativeproductsandincreasingmarketshareenhancedbrandimagethroughmarketingandcommunicatingtheimprovementeffortsincreasedproductivityandemployeeconfidencethroughcloseralignmentofcompanyvalueswiththepersonalvaluesoftheemployeesimprovedenvironmentalperformancebyreducingtoxicemissions,andincreasingtherecoveryandreuseofwastematerial29DynamicBiochemistry,ProcessBiotechnologyandMolecularBiology4(1),1-362010GlobalScienceBooksEco-Efficiencyanalysesshowedthatthereissomepotentialforbiobasedmaterialsandwhitebiotechnology,andthatthegreatestimpactofwhitebiotechnologymaybeinthefinechemicalssegment,whereupto60%ofproductsmayusebiotechnology(EuropaBio2004;Saling2005).
Inaddition,theeconomicandenvironmentalimpactsarefavourable(Table19)(Saling2005).
CONCLUDINGREMARKS-ENVIRONMENTALBIOTECHNOLOGYCHALLENGESANDPERSPECTIVESNewenvironmentalchallengescontinuetoevolveandnewtechnologiesforenvironmentalprotectionandcontrolarecurrentlyunderdevelopment.
Also,newapproachescon-tinuetogainmoreandmoregroundinpractice,harnessingthepotentialofmicroorganismsandplantsaseco-efficientandrobustcleanupagentsinavarietyofpracticalsituationssuchas(Urbainetal.
1996;vanWyk2001;GrommenandVerstraete2002;Cicek2003;KohliandMartin2005):enzymeengineeringforimprovedbiodegradationevolutionaryandgenomicapproachestobiodegrada-tiondesigningstrainsforenhancedbiodegradationprocessengineeringforimprovedbiodegradationre-useoftreatedwastewaterbiomembranereactortechnologydesignwastewatertreatmentbasedondecentralizedsanitationandreuseimplementationofanaerobicdigestiontotreatbio-wastebiodevelopmentofbiowasteasanalternativeandrenewableenergyresourceemergingandgrowing-uptechnologicalapplicationsofsoilremediationandcleanupofcontaminatedsitesAlongwithawidegroupoftechnologieswiththepot-entialtoaccomplishtheobjectivesofsustainability,bio-technologywillcontinuetoplayanimportantroleinthefieldsoffoodproduction,renewablerawmaterialsandenergy,pollutionprevention,bioremediation.
Sinceenvironmentalbiotechnologyprovedtohavealargepotentialtocontributetotheprevention,detectionandremediationofenvironmentalpollutionanddegradation,itisasustainablewaytodevelopcleanprocessesandpro-ducts,lessharmful,withreducedenvironmentalimpactthantheirforerunners,andthisroleisillustratedwithrefer-encetocleantechnologyoptionsintheindustrial,agrofor-estry,food,rawmaterials,andmineralssectors.
Sincesomenewtechniquesmakeuseofgeneticallymodifiedorganisms,regulationtoguaranteesafeapplica-tionofnewormodifiedorganismsintheenvironmentisimportant.
Awiderangeofbiologicalmethodsarealreadyinusetodetectpollutionincidentsandforthecontinuousmoni-toringofpollutants,butnewdevelopmentsareexpected.
Environmentalandeconomicbenefitsthatbiotechno-logycanofferinmanufacturing,monitoringandwastemanagementareinbalancewithtechnicalandeconomicproblemswhichstillneedtobesolved.
Allthisisbeingachievedwithreducedenvironmentalimpactandenhancedsustainability.
Anevaluationoftheconsequences,opportunitiesandchallengesofmodernbiotechnologyisimportantbothforpolicymakersandtheindustry.
ACKNOWLEDGEMENTSThisworkwassupportedbytheProgramIDEI,GrantID_595,ContractNo.
132/2007,intheframeoftheNationalProgramforResearch,DevelopmentandInnovationII—MinistryofEducationandResearch,Romania.
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