生化联合处理浓缩果汁废水外文翻译二

本科生毕业设计外文翻译TreatmentofconcentratedfruitjuicewastewaterbythecombinationofbiologicalandchemicalprocessesConcentratedfruitjuiceindustriesuseawidevolumeofwaterforwashingandfruitprocessing,generatingalargevolumeofwastewater.Thisworkstudiedthecombinationofanaerobicbiologicalprocesswithachemicalcoagulation/flocculationsteptotreatahighconcentratedfruitjuicewastewater.Thiswastewaterpresentsagoodbiodegradability(BOD5/COD=0.66)allowingachemicaloxygendemand(COD)removalabove90%inmostreactors.Thebestresultsinaerobicbiologicaltreatmentwereobtainedinreactorsinitiallyloadedwith2gVSSL−1ofbiomassconcentrationand20gCODL−1oforganicmatterconcentration.Threedifferentkineticmodelswereevaluated.TheHaldane-inhibitionmodelwastheonethatbestfittedtheCODbiodegradation.AQUASIMsoftwareallowedcalculatethefollowingkineticconstantsrangesforaerobicbiodegradation:Ks:6–20gCODL-1;Vmax:2.0–5.1gCODg-1VSSday-1andKivalues:0.10–0.50gCODL-1.Theseconstantscorrespondstomaximumremovalrates(v∗)between0.11and0.26gCODg-1VSSday-1forsubstrateconcentrations(S∗)from0.77to3.16gCODL-1.Atertiarycoagulation/flocculationprocessimprovedtheefficiencyofthebiologicalpre-treatment.Ferricchloridewasselectedasbestcompromisetotreatthiswastewater.Optimalconditionswere0.44gL-1ofcoagulantatpH=5.5,achieving94.4%and99.6%onturbidityandCODremoval.Foodandbeveragesprocessingindustriestransformagriculturalrawmaterialsintointermediatefoodsandedibleproducts.Inthecaseoffruitjuices,rawfruitsareusuallyusedthroughaseriesofsequentialoperationsandprocessestoproducejuiceconcentrates.Duringtheseoperationslargevolumesofwaterareconsumedwithconsequentwastewatergeneration,whicharehighlycontaminatedwithorganicmatterandsuspendedsolids.Dependingonthemethodsandequipmentsusedwastewaterswillpresentdifferentphysicochemicalcharacteristics.Fruitjuicewastewaters(FJW),likeallwastewaters,mustbeproperlytreateduptoanecessaryleveltocomplywiththeregulationsofdischargeintosurfacewaters.Alternatively,itcanbereusedinagriculturalpractices.Biologicaltreatmentmethodshavebeenrecognizedasareasonableoptiontotreatwastewaterswithahighorganiccontent.However,thepresenceofbiorecalcitrantcompoundsfrequentlymakesimpossibletoachieveanefficienttreatmentofthesewastewaters.Apossiblesolutiontooverpassthissituationcanbethroughthecombinationofbiologicalandchemicalprocesses.Biologicaltreatmentmineralizesthelargebiodegradableportion,reducingeffectivelytheCODofthewastewater.Finally,thechemicaltreatmentdegradestheremainingpersistentcompounds.Physicochemicaltreatmentssuchascoagulation/flocculationcanbeasuitabletechniquetoreducethepollutingloadofeffluentsand,particularly,thecolloidalparticlesandnaturalorganicmatter.Colloidalparticlestypicallyhaveanegativesurfacecharge.Thesizeofcolloids(from0.01to1µm)issuchthattheattractivebodyforcesbetweenparticlesareconsiderablylessthantherepellingforcesoftheelectricalcharge.Coagulationisacommonlyusedprocessinwater/wastewatertreatment,wherecompoundssuchasaluminiumandironsaltsareaddedintoeffluentstodestabilizethecolloidalmaterialandagglomeratesmallparticlesintolargerandsettleableflocs.Severalstudieshavereportedtheapplicationofcoagulation/flocculationprocessestotreatindustrialwastewaters,determiningtheoptimalexperimentalconditions,suchaspH,coagulantdosageandtheinfluenceofflocculantconcentration.Thisresearchworkintendstoinvestigateasimpleandlow-costtreatmentsystem,throughthecombinationofanaerobicbiologicalprocessandacoagulation/flocculationpolishing.ThemaingoalistocomplywiththePortugueselegislationofwastewaterdischargeintonaturalwaterbodies.Theaerobicbiologicalstepwillevaluatetheremovalofdissolvedorganicmatterusingdifferentaerationperiods.Thepost-coagulation/flocculationprocessaimistoimprovethefinalcharacteristicsofthebiologicallypretreatedeffluentthroughtheselectionoftheoptimalcoagulantdosageandpH.COD,totalpolyphenols(TP),totalsuspendedsolids(TSS),volatilesuspendedsolids(VSS)andturbiditywillbemonitored.Wastewatersampleswerecollectedinaconcentratedfruitjuiceindustry,locatedinthecentreofPortugal,wherepearandappleconcentratedsyrupsareproduced.Theeffluentpresentsadarkcolorandstrongodourcharacteristicofthefruitsusedintheprocess.FromdataitispossibletoverifythatthesewastewaterspresenthighCOD,TOCandBOD5concentrationsalliedtoaconsiderableamountofsuspendandvolatilesolids.TheBOD5/CODratio(0.66)revealsawastewaterwithhighbiodegradability.Aerobicbiodegradationexperimentswerecarriedoutin4Lcylindricalaeratedbiologicalbatchreactors.Thesereactors,workingatenvironmentaltemperature(20◦C),wereprovidedwithcoverscontaininginletsforfeedbubblingatmosphericairandoutletsforsamplingandventing.Theairflowwasfedtothereactingmediumthroughabubblegasspargerataconstantflowrateof125Lh-1withthreedifferentaerationperiods:6,12and18h/day.Theactivatedsludgeusedasinoculumwasobtainedfromanaerobicstageofafull-scaleurbanwastewatertreatmentplantandpreviouslyacclimatedtofruitjuicewastewaterfor3days.Bioreactorswereinitiallyloadedwiththefruitjuicewastewaterandtheinoculumsludge.Experimentswereperformedvaryingtheinitialbiomassconcentration(X)andtheinitialorga