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ENVIRONMENTALSCIENCEANDENGINEERING(BCE101)
RequirmentofHumanBeing:
Energy Water Quantitative&Qualitative Food
EnvironmentEngineersWorkToprovidegoodqualityofwater
(Watertreatmentplant)
WastewatertreatmentControlonAirPollutiontoMaintaintheAirQuality
(Temperature,Pressure,Wind,Moisture)
ControlonWaterPollutionSolidWasteManagement
(Storage,Separation&Transportation)
1BookEnvironmentEngineeringByGerardKiely2H.S.PeavyD.R.RoweG.TechnobanogLous3WaterSupplyEngineeringbyS.K.Garg
1.1 EcologicalPerspective:
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The environmental engineer is interested to use the varies physicalresourcessuchasnaturalenergy (waves,wind,minerals,hydroelectric)andwaterfordomestic&livingpurpose.
Therefore, It has tounderstand the functioningwith the living systemanditsinteractionwiththeenvironment.
Environment(orEcosystem)Itconsistsoffourmajorelementsuchas(i) Land(ii) Water(iii) Airand(iv) LivingOrganism(Plant&Animals)
Environment(Ecosystem)
PhysicalEnvironment BiologicalEnvironment(Abiotic) (Biotic)
LivingOrganisms(Planteanimals,Viruses,Bacteria,Fungi)
Hydrosphere Lithosphere Atmosphere(Waterovertheearth (Solidearth&soils) (airuptoadistance&insidetheearth) of700km.)
Livingorganismsaredependentoneachother&dependson thephysicalenvironment.
Ex. Plansgrowonland&inwater.Herbivorousanimalsusetheplantasfood.Carnivorousanimalseatherbivorousanimals.
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1.2 ValueofEnvironment:orResources
NaturalResources
Renewable Nonrenewable(Energyfromsun,water (Fossil,Fuel,Mineralsetc)andBiologicalcycles)Itisrecycled&reused. Theyarenot
Replaced.ForestPlantation Amountarefinite.
Abstract(Animal,plantandnaturalsightusedfortourism)
1.3 EnvironmentAuditing:Listingofalltheresourcesofanarea
Differenttypesofdevelopmentalworkgoaheadinanareadependsontheeconomicalconsideration.
Ithastorestricttheeconomy(money)cased.
Therefore,Wehavetoauditormakealistofalltheresourcesofthearea.(Environmentalauditing)
Auditing
Nosofspecies(Livingorganisms)exist
Usesofthelivingenvironment.
Directuses Indirectuses
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Food,Industrial&Commercialproducts,tourism,medicinesetc.
1.3.1 DirectuseFoodPlantsordomesticatedanimalproducts
Industrial & commercial products: Mineral, fossil, fuel, wools, cotton,jute,rubberetc.
Medicines
1.3.2
IndirectUses
9 Biodiversityisthebiologicalprocessesthemselvesthatprovidethevalue.Itisregardingaboutindirectusesofenvironments.
9 Environmentconsistsofpopulationsofspecieswithair,water,land.
Populationofonespecies(Environment)
Biological mixedtogetherwithother
Processhelps species
Theentiresystem. Communities
Manycommunitiesare
Combined
Landscape
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9 Therefore, biodiversity is a basic resourcewhich acts as a human lifesupportsystem.
9Biodiversity
Sail formation,wastedegradation,air&waterpurification,solarenergyabsorption,andmaintenanceofhydrologicalcyclesetc.
LossofBiologicalresources
Reductionofonecommonspecies. 1Depletionofaoncecommonspecies
2Localorglobalspeciesextinction
3 Ecosystemdisruption
Environment may be changed due to habitat destructionextinction means the potential of the particular species to beappearedinfuture.
1.4.0 CostBenefitAnalysis:
Afterenvironmentalauditing,wehavetocalculatethecostfor
thedevelopmentalwork.
Someof the environmental process or services are excluded fromthecalculationsuchas:
9 Pollutionabsorptionbybioticsystem9 Ecosystemstability9 Recreationalvalue
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9 Historicimportance.
Environmental parameters to be incorporated is based on WorldConservationStrategy(IUCN,1980).
1.5 BioticComponent:
Everythingintheglobalenvironmentisinonecomponentcanaffectmanyothersoverspace&time.
Sixmajorlevelsofecologicalorganizationarerecognized
9 Individual(Physiologicalfunctions)Singlespecies
9 Population(Birth,death,populationgrowthrate)9 Community(Interactionbetweendifferentspecies)
Bothplants&animals
9 Ecosystem(Interactionbetweenliving&(biotic)
Nonlivingcomponent.)
Abiotic
Biotic
CommunityofLiving
Hydrosphere
(Water)
Lithosphere
(earth,soil)
Atmosphere
(Air)
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ABiotic
Fig1Interactionsbetweenvariouscomponent
EnergyflowoccursatthelevelofEcosystem
9 Biomes: Environmental conditions are similar indifferentpartsofcountry.
Exclimate.Vegetationtype.
9 Biosphere: Part of earth & atmosphere in which lifeexists.(Lithosphere, Atmosphere & Hydrosphere comes intocontactinBiosphere)
1.6 EcosystemProcess:
Ecosystemistheinteractionbetweenbiotic&abioticcomponents(Fig1).
Processoccurredatecologicallevelare
9 Energyflow9 Nutrientcycling
1.6.1 EnergyFlow
Interactions between living organism & environment is because ofrequirementoffoodwhichsupplyenergytosurvive
Italsohelpstoconstructbodytissues&gamesforreproductionofspecies. (child/nextgeneration)
Energysources
converted1Lightenergychemicalenergy
(storedinlivingorganism)
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SolarenergySun(ultimatesourcesofenergy)
2EnergyinEnvironment
AutotrophicHeterotrophic(Energyoriginated
Fromprimaryproductioninotherecosystem.)
twoways1Productionofenergybygreenplantsinpresenceoflightthroughtheprocessof
photosynthesis.2Bysulphuroxidizingbacteriaindeepseaecosystems.
PhotosynthesisGranplantscreatetheirownfoodthroughaseriesofchemicalreactions.12H2O+6CO2+LightChlorophyII+enzymes
Water709kcalC6H12O6+6O2+6H2OCarbohydrate(toair)(Glucose)+Sugarmolecules.
Photosynthesisiscarriedoutindaylightinleaves&instemsofsomegreenplants.
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Plantrequireinorganicsubstancelike
9 Nitrogen9 Phosphorusobtainedfromsoils.9 Magnesium9 Iron
Glucose+chemicalreactionFat,Proteins&Nucleicacid(usedtoformbodytissues)PrimaryproductionProductionoforganicmatterbyplants.
Whenanyorganismrequiresenergy,thereversereactiontophotosynthesisoccurs,celledrespiration.C6H12O6+6O2metabolicenzymes
CO2+H2O+EnergyforworkPrimaryProductionTheproductionoforganicmatterbyplantsiscalledprimaryproduction.
The rate of photosynthesis & primary production plays a vital role in theecosystem.Therefore,Ithastoconsidertheamountofprimaryproductionindifferentecosystem.Netprimaryproduction=GrossPrimaryproductionrespirationGrossprimaryproduction is thetotalamountofchemicalenergystoredbyplantsperunitareaperunittime.Theprimaryproductionisaffectedbytheenvironmentalfactors,
9 Water9 Light9 Soilnutrients9 Temperature.
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Foodchain
Autotrophs(plants)cancreatetheirownfood,butheterotrophscannot.
(animals)
Heterotrophdirectlyorindirectlydependsonprimarysourceoffood.
Primaryproductionplant
(chemicalenergy)
+Organicmatter
(GrossProduction)
1.6.2 Decomposition&NutrientRecycling
Nutrient:aminoacids,minerals,sugar,salts&vitamins.
With flowof energy through food chain, nutrients arepassed fromone organismtoanotherduringfeeding.
AutotrophOrganicmatter
Photosynthesis
respiratory Netproduction
to
Herbivores
Carnivores
SunlightPhotosynthesis Respiratory
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Sunsenergy
R
R
R
R
Fig4Energyflow
Plant
Primaryproducer
Decomposer Primaryconsumer
Secondaryconsumer
Soil Rain
Primaryproduct
DecomposerPrimaryconsumer
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Herbivores
Carnivores
Fig5Nutrientcycle
1.7EnvironmentalGradients&Tolerance:
Eachspeciesisnotfoundineverytypeofhabitat(area)Unevendistributionoforganism
Thisisbecauseofseveralfactors
9 Light9 Temperature9 PH9 Food9 Water9 Shelter9 Predictor&competitorsinteraction.
Theaboveenvironmentalfactorsvariesfromtheequatortowardsnorthorsouth;iscalledenvironmentalgradient.
Theplotbetweenenvironmental&populationsizeiscalledtolerancecarve.
++++++++++++
A=Speciesabsent
B=Lowpopulation
Secondaryconsumer
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Rangeofoptimum:Areaofgreatestnumbers.
ConceptofHydrology2.1Hydrologicalcycle:
Water evaporates from oceans & other water bodies, and from landsurfaces. The evaporated water rises into the atmosphere until the watervapour condness. Then the condensed water vapour condenses. Then thecondensedwatervapourintheformofrain&sometimesassnow.
++++++++++++++++
Fig2.1Hydrologicalcycle.2.2Waterbalance:
Theaccountingofwaterforaparticularcatchment,regionorearthiscalledwaterbalance.
Therefore,waterbalanceistheaccountofhydrologicalcycle.Moreover,theinputtothehydrologicalcycleisduetoprecipitation.
theequaforwaterbalanceis
P=Precipitation,mm/day
R=Streamrunoff
E=Evaporation
S=Changeinsoilmoisturestatus
G=Changeingroundwaterstatus
2.3 Energybudget/balance:
P=R+E SG
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Thesourceofenergyissolarradiation.Earthsurfaceabsorbssolarradiation.
Theenergyabsorbedbyearthsurfaceisreflectedbacktotheatmosphere& some enters into the earth. Furthermore, the earth also reradiates somesolarenergy.
The energy balance is the accounting of distribution of the solar radiationthrough atmosphere and onto the earths surface of land and ocean.Moreover, It accounts for the outgoing terrestrial radiation from the earthssurface.
It includes evaporation flux, sensible heat flux & net radiant emission bysurface.
Ourinterestisfindthenetincomingradiationattheearthssurface.
Quantityofradiantenergyremainingattheearthssurface.
WhereRn=Specificfluxofnetincomingradiation,W/m2
L=Latentheatofvaporization(Doesntincreasethetemperature)
E=specificfluxenergyofsensibleheatintotheatmosphere(watt/m2)
G=Specificfluxofheatintooroutofthesoil
PS=Photosyntheticenergyfixedbyplants
M=Energyforrespiration&heatstorageinacropcanopy.
NeglectingPS&M,wehave
2.4Precipitation:
Rn=LE+H+G+PS+M
Rn=LE+H+G
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Preciptionisintheformofrain,hailorsnow.Weareinterestedtodeterminetheamount,rate&durationofprecipitation.
Themagnitudeofrainfallisdeterminedbythreewayssuchas:
9 Precipitationgauges9 RaderInstruments9 Satelliteremotesensing
Precipitationcanbecalculatedfromdifferentmethodanalysisresultsi.e.
9 Areaprecipitation9 Deptareadurationanalysis9 Precipitationdurationfrequencyanalysis.9 Intensitydurationfrequencyanalysis.9 Extremevaluesofprecipitation.
Areaprecipitation
P1=.dx
MeanareaTotalaccumulationPrecipitationofprecipitationatallpointx1inthecatchment
Timeaveragedmainareaprecipitation
MP2=
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I=1AATotalprecipitationatx&timeti.Where
A=CatchmentareaT=Totalstormperiod.
Depthareadurationanalysis.Generally,astheareaofacatchmentincreases,thedepthofprecipitation
decreases.Therefore,anareareductionfactor(ARF)Isusedforprecipitationinthisanalysis.
Precipitationfrequency
Rainfallrecordoveraperiodoftimewithaspecificmagnitude.(No.oftimes)
+++++++++++++++++Fig2.3DepthareadurationcurveIntensitydurationfrequencyanalysis(IDF)
FromIDFcurves,asrainfallintensityincreases,itsdurationdecreasesi.e.
Runoff(Q)=CIA
Catchmentarea(km2)
Localityconstants.
2.5 Infiltration:
Itisthemovementofwaterfromsoilsurfaceintothesoil.About76%ofprecipitationinfiltrateintothesoil.
I
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1 Thepropertiesofsoilwhichresponsibleforinfiltrationare
9 Bulkdensity9 Particledensity9 Porosity9 Volumetricwatercontent9 DegreeofSaturation.
Bulkdensityofasoilis:
(b)
Md=Drymassofasoilvolume
Vt=totalvolume(Undriedcondn)
Particledensity(m)=
Vd=dryvolume
Typicalvalueformostsailsis2.65kg/m
Porosity()==1
Va=volumeofair
Va=volumeofwater
Vs=volumeofsolids
b=()
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VolumetricWatercontent()==
Degree of saturation (S) is the proportion of water containing pores. of the
measureofwetness.
S==
SoilhorizonsandHydraulicconductivityHydraulicconductivityistherateof
movementofwaterintothesoil.
Deadleavesvegetation(Grass,tree)
UnsaturatedzoneAHorizon
BHorizon
CHorizon
3Soilmoisturecontentorsoilwatercontent
Eachsoilhasamaximummoisturemagnitude/capacity,whenitissaturated.
+++++++++++++++
Aerationzone:istheupperzonewheretheporesareoccupiedbyair.
Capacityzone:isthezonethroughwhichwaterwillrisethroughthesoilpores
bycapillaryaction.
Groundwaterzone:existsbelowthewatertable.
2.6Evaporation&Evapotranspiration:
Soil
Subsoil
Saturatedsoil
BedRock
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Evaporation is the process by which water is returned to the
atmosphere,fromliquid&soildintothevapourstate.
Evaporationintotheatmosphereoccursthroughthetranspirationofleaf
partsofplants.Theprocessistermedasevapotranspiration.
30% of rainfall flows in the form of runoff. Therefore, on the ocean
surfaceofearththereismoreevaporationthanprecipitation.
Thetypeofevaporation/evaporatranspirationare:
9Evaporationfromlakesurface(Eo)9Actualevapotranspiation,(ET)9Potentialevapotranspiration(PE)
Evaporationfromlakeoropenwaterbodysurface.
Itincludestheevaporation&transpirationfromalandsurface,&vegetated.It
willvarydependingonthepresentsoilmoisturestatus.
Potential evapotranspioration is determined for catchment research
projects,whenradiation&heatbalanceareconsidered.
Factors causing evaporation from any surface are: 1 Latent heat of
vapourization&(2)wind
2.7Groundwater:
Groundwaterisdefinedasthewaterbelowthewatertable.
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The levelof soilbelowwhich theporespace is100%occupiedby
water.
2.7.1Aquifers
Watertable
+++++++++++++++
An aquifier is a water bearing rock formation that contains sufficient
amountsofwatertobeexploited&broughttothesurfacebywells.
Aquifersaretwotypesinnature:
9 Contined9 Uncontined
Upperaquiferisunconfined&ithasanaturalwatertableline.
Freetomoveup&down
The impermeable strata between unconfined aquifer& confined aquifer is
calledaquaclude.
Whenwellsaredrilledintoconfinedaquiferwaterwillrise&attainitsown
watertableline.
2.8Groundwaterchemistry:
(quality/properties)
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Thequality of groundwaterdependson the subsoil& rocks that it passes
through.
Ex:hardness,iron,manganese
1 Hardness
WhenGroundwaterpassthroughthelimestone,itdissolves/mixedwith
calcium & magnesium compounds; which cause hardness. (200 to 400
mg/litr)
2 Iron&Manganese
Excessamountofironsdontcausehealthproblem(Tasteproblems)
Itwillgiveametabolictastetowater.
Manganesecauseablackdiscolorationofwater.
Iron&manganesearegoodindicatorofwaterpollution.
3 Hydrogensulphide(gas)
H2Sispresentinwaterfromrockslikelimestonesorshales.
ItcreatethesameproblemasinthecaseofIron.
4 Sulphate(800mg/lit)
5 SodiumChloride(Nacl)
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Thisproblemoccursinareaswhererocksarehighlypermeable.
2.9 Ground water contamination: internet Make impure which will
becomeharmful
TheindicatorsofthesourceofcontaminationareE.coli,nitrate,ammonia,
potassium,chloride,iron,manganeseetc.
1 Bacteria&Viruses.
E. coli is the parameter which indicates the presence of bacteria &
viruses.
Presence of bacteria in ground water causes typhoid fever, diarrhea,
gastrointestinalinfectionetc.
EcoliBacteriaFromseptictankeffluent,landfillsites&birdsetc.
2 Nitrate
Nitraterichwatercausemathaemoglobinaemia(bluebabysyndrome)to
youngchildren.
3 Ammonia
Ithasalowmobilityinsoil&subsoil.
4 Potassium(K)
Itisimmobileinsoil.
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5 Chloride(Cl)
6 Iron&Manganese
2.10Groundwaterpollutioncontrol/prevention:
WaterQualityRequirement:
3.1InStreamStandards:
Waterqualityrequirements&waterqualitystandard.
Manyfactorsaffectstream
Qualityex:Wastewaterdischarge&humanactivities
3.2Portablewaterstandard:
+++++++++++++
3.3Wastewatereffluentstandards:
Decomposition:Theprocessofdecaycausedbybacteria&fungi
:WaterQualityinRivers:
4.1OrganiccontentparameterDO&BODinstreams
DODissolvedoxygen.
Waterbodiessupportavarietyoffishandanimals.Theyrequire
oxygen&astream/rivermusthaveaminimumdissolvedoxygenabout
2mg/litr.
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Whenanorganicwasteisdischargedtoastream,theorganiccontent
undergoesbiochemicalreaction.Thisreactionaconsumesoxygenfrom
waterbodies.
Organiccontent+O2microorganism
New+Co2+H2O+stableproducts
Biomass
Theamountofdissolvedoxygenusedupfromwatersamplebymicro
organismforthebiochemicalreactionistermedasBOD.
TherelationbetweenDO&BODisdevelopedbyStricter&Phelps
model.
Follow=K1LtK2DO
otherbook=
Lo=Oxygendemandatt=to
Lt=CBOD(mg/Litr)
=Carbonaceousbiochemicaloxygendemand
amountofoxygen
Remainingattimet
ConstantsK1dexygenationrate(1/day)
K2reactionrate(day1)
(LoLt)Oxygenconsumed.
K1L0eK1tK2DO
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Thedissolvedoxygen(Do)decreasesinariver/streambydegradationof
BOD.ThevariationofDOinthestream/riverw.r.tBODwasderivedby
Streeter&helpsmodel.
Seededwater
Deoxygenation
ChemicalOxygenDemand(COD):Aquickchemicaltesttomeasurethe
oxygenequivalentoftheorganicmattercontentofwastewaterthatis
susceptibletooxidationbyastrongchemical.(organic&inorganic)
(both)
OrCODisameasureofthetotalorganiccarbonwiththeexceptionof
certainaromaticsuchasbenzenewhicharenotcompletelyoxidizedin
thereaction.
Organicmaterialssuchascellulose,phenolsetc.resistbiodegrationalong
withpesticides&thesematerialsareoxidizedintheCODtest.
*Theorganiccontentofawastewaterstreamisdeterminedbyfollowing
tests.
BOD5:conc.OfDoatday5
COD
TOC:Totalorganiccarbon,
atdayOatday5
BOD5=P(DOiDos)
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Dilationfactor.
4.2Transformationprocessinwaterbodies:
TheconstituentsinwaterbodiesareDO,BOD,temperature,salinity,
nitrogen(asorganic,ammonia&nitrateetc),phosphursetc,(considering
waterquality).
Thetransformationprocessinwaterbodiesare:
1 Influentcleanflows
2 Influentwasteflows
3 Biologicaloxidationofcarbonaceous&nitrogenousorganicmatter.
4 Reparationofsurfacelayer
5 ReductionofBOD(sedimentation)
6 Photosynthesis
7 Respiration
8 Oxygendiffusion
9 COD(Chemicaloxygendemand)
4.3Transportprocessinwaterbodies:
Transportprocessesare
1 Advection(heat,humidity&solidityinocean)
2Difusion:theprocessbywhichmodelsSeeS.K.Garg
intermingleasaresultoftheir&otherBook
extwogasesmixK.E.ofrandommotion.Fordestination
-
withcostivelyoftheprocess
3Buoyancy:isanupwardforexertedby
fluidthatopposestheweighofimmersedobject.
4.4StricterPhelpsOxygenSagModel:
Therateofdecompositionoforganicmatterisproportionaltotheamountoforganicmatteravailable;i.e.
11
Lt=BODremainingattimet,K1=deoxygeneationratecoefficientperday
Integrateequation1between(Lo)to(Lt)
Wehave2
WhereLo=UltimateBOD
=(BODattintO)=initialBOD
BODconsumedattimet.
(BOD)t=LoLt
=LoLoeK1t
=Lo(1eK1t)
Solve
Ex7.1
=K1Lt
Lt=Loek1t
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7.3
Whenbiodegradablewastewasdischargedtoastream/river,Itconsumed
oxygen.
Thedeticienyofdissolvesoxygenismaintainedthroughreaertionfrom
atmosphere.
Hence,eqa1canbewrittenas
=K1LtK2(DO)
=K1Loek1tK2(DO)
3
WhereDO=DOdeficit(oxygendeficit).
=maintainDOactualDO
LtOxygenremainingattimet
K1deoxygenationrateperday
K2=reparationrateperday
Integratingeq,wehave
DO(t)=(ek1tek2t)+
DOek2t
4
WhereLo=Oxygendemandatt=to
Doo=dissolvedoxygendeficitatt=to
Dissolvedoxygensaturationdeficitatanytimet.
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Equ4isthestreeterPhelpsoxygensagformula.
Solveex7.5
InitialDODOcDOsagcurve
DeficitminReaertimDO(mg/lit)
deoxygenation
time
FigDissolvedoxygensagcurve
DocMinimumormaximumdissolvedoxygendeficit
differentiateequ4w.r.ttot&setitequaltozero.Wehave
tc=.Ln1
timeofoccurrenceofminimumDOormaximum
dissolvedoxygendeficitDOc
=DO(t)DOo
Dissolvedoxygensaturationdeficitattime.
ChemicalPretreatment:toremoveundesirablepropertiesofwater(excess
colourofalgae)Photosyntheticalghe.(doubt)
Unit(NTU:Nephelonetricturbidityunit)
Prechorinctinfor(Lowturbiditywater)
-
Activaledcarbon
(Turbidity:Shouldbe
-
OxygenO2contentisincreasedtorechesthebadtaste(metabolic
taste).
Additionofoxygenhelpstoseparatethesubstance(Iron&
manganses)inasolidform.
Adsorption:theaccumulationofgas,liquidorsolutesonthesurface
asolid/media.
Sedimentationtank(settingtank):(I)dissolveparticiple
=
Flowvelocityinhorizontaldegree.
Vs=settingvelocity
Therearethreezonesinthetank.
1 Inletzone
2 Outletzone
3 Sludgezone
Sedimentationofflocculentparticles:(II)
Settingofflocculentparticles.
V=()xVs
-
Coagulationisthefirstprocessofaddingthecoagulantwhichchanges
theparticleselectriccharges&thenhelpstoaggregateinmass.
Flocculationisthesecondprocessofgettingthecoagulatedmixto
formlargerflocs.
Beforeflocculationcolloidalparticlesaresuspendedinaliquid¬
dissolvedinthesolution.
Incoagulationprocesscoagulantswithoppositechargetothe
suspendedsolidareweldedtoneutralizethevechargesondispersed
nonsettablesolids.
Ex7.1Asampleofwastewaterisdilutedwithaseededwater&isplaced
inanairtightbottle.MeasuretheconcentrationofDOatignitionday.
1 PretratmentProcess:
9 Screening:Coarseserreemy(25mm100mmsize)9 Storage9 Aeration(ToreleaseexcessH2S,CO2,O2)9 Chemicalpretreatment.(Prechlorination&Activatedcarbon)
Screeny
Coarsesereeny(25mmdiabar&100mmspellingisusedtopreventlargefloatingmaterial)
FixSereen(6mmdiaopening)Aobstructionis
Microscreen(2040Nmopening)madewithwovensteel
Wirenet.
-
Storagetankareusedforsettlementofsuspendedparticles
(initialsettingtank)
9 Thismaybeusefultoreelncepathogensbyexposuretodaylight.9 Timeofstorageisabout12hr.Aration:issupplyofoxygenfromatmospheretowatertochangequalityofwater.
(PH,hardness,manganese,H2Setcinaspecifiedanomy)
Aerationisusedtorelease(H2S),which
releaseCO2,whichiscorrosiveinnature.
:WaterTreatment:
5.1Watersources&theirquality:
Differentwatersourcesare
9 Rivers9 Lake&reservoir9 GroundwaterQualityofwaterare:
PH,Acidity,Alkalinity,Colour,Turbidity,DO,etc.
Disonfeet
Sedimentation,Coagulation(Fitration)
5.2WaterTreatmentOperation:
5.2.1Sedimentation
Pretreatment Primarytreating Secondarytreatment
-
Theseparationofsuspendedsolidsfromtheliquidbygravitysetting
processisreferredassedimentation.
Sedimentationofdiscreteparticles(I)
Separatepart
9 Settingtanksarecircular/rectangular.Particlessettleoutindividuality.Thedesignofsuchtanksarebasedonsettingvelocity.
Aparticlewillaccelerateverticallydownwardsuntilthedragforce
(FD)equalstoimpellingforce(F1).Thenparticlewillsettleata
constantvelocity.
Stokesvelocity(V2)
F1=(sw)V
s=densityofsolidparticles(Psg)
w=densityofsolidwater(Pwg)
V=Volumeofparticles
FD=CDAsPw
CD=Dragcolficient
=0.4forspheres.
As=spheresectionarea.
Vs=stokesvelocity
-
V=kinematicviscosity=
Sedimentationofflocculentparticles(I)
Flocculent:cloudlikeaggregations.
Flocculentparticlesarethoseparticlesthatarechemically(Addthechemical)
assistedtocometogether&producelargeparticle&settle.
5.2.2(Coagulation:
Iftheparticlesizerangeisbetter107to101mm,thenbecauseofsmall
size,thesuspendedmatterhasnegligiblevelocity.Tosettletheseparticles,we
usechemicalcoagulanttocollecttheparticlesinmass.
Coagulant:Aluminumsulphate,ferrous,sulphete&ferricchloride.
Whenalumisaddedtorawwater,thereactionis:
Al2(SO4)3.14H2O+3Ca(HCO3)2
Alumcalciumbicarbonate
PH=PotentialofHydrogen(VariesfromOto14)
=Itisthelogarithmofthereciprocalofhydrogenionconcentrationingram
atomsperlitre.
=7(Basic/alkalining)
-
FlocGelatinousparticle(Asmalljellyaggregatemassformed.)
Itthereisinsufficientalkalinityinwater,limeisaddedtowater.Thereaction
is:
Al2(SO4).14H2O+3Ca(OH)2
CalciumHydroxide
Then,thesmallparticlesattachedwiththeflockmass&producealarger
mass&itsettlesdown.
Solve.
Ex.11.3,11.4
5.2.3Filtrationistheprocessofpassingwaterthroughaporousmedium.,(ex
sandlayer).
Usuallysandfiltrationhasbeenusedfortheporousmedium.
Classificationoftitrationsystemare
9 Gravityorpressure9 Rapid/slowfiltration9 Depth/cakefiltration
Gravityfiltrationistheprocesswherewatergoesthroughfilteronly
bygravityforce.
PressurefiltersWaterisforcedthroughthefiltermediaunder
pressure.
-
Slow/rapidfiltration
Slow:filtrationrate(0.1to0.2m/hmeter)
Rapid:filtrationrate(5to20m/h)
Depthfiltrationiswheremostofthedepthofthefiltermediumis
activeinthefiltrationprocess.
SlowSandFilteration
Supernatantwater
Schmutzdecke
Sandfiltered
Inlet
Structure
Systemofunderdrain.
Waterenterthroughinletandflowerontheschmutzdeckelayer.
Thislayeriscomposedofliving&deadmicroorganisms.
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TheSupernatantwaterprovidessufficientwatertodrivethrough
thesandfilter.
Thefilterbdisoffinesand(0.15to0.3mm)
Inshowsandfiltration
Totalcoliformbacteriaremoval(99.4%)
Removalofparticlewithsizes1to60r&m
Colourremovalisnotsignificant.
Turbiding(waterwithfineclay/mueldyparticles)removalis25%
Slowsandfiltrationfiltersabout26month.
RapidGravityFilters
InfluentWaterheadcoarsematerialFinesand
+++++++++++++++++++++++++++++++
Rapidgravityfiltersareusedtofilterchemicallycoagulatedwater&
producehighqualitydrinkingwater.
Biologicalactivityoccurinthebreakdownofammoniatonitrateas
innitrification:
NH4+2O2NO3+
-
AmmoniaBacteriaNitrate
2H++H2O
Filtrationoperateswithaheadofabout1mofwater.
Maintainsamefiltrationrate
Waterorcompressedairfrombottomissentupthroughbackwash.
(BackwashVelocity>0.3melm/min)
Waterisrecycledthroughtheplant.
Filtrationoperatedonhydraulicprinciple.
Vf=Vtxf4.5
Porosity
Terminalvelocitytowashmediumfrombed
5.2.4Disinfection
Itreferstooperationsusedtokillpathogenicmicroorganisms.
Sterilizationistheprocessforthecompletedestructionofallliving
matter.
Disinfectiondoesntindicatetosterilizationprocess.
-
90%ofbacteria&virusesareremovedbycoagulation&filtration
process.
Therateofdestructionofmicroorganismisalchemicalreaction
(chickslaw)
=kNt
solun
Nt=Nooforganismsattimet
No=
K=rateconstantofthetypeofdisinfectant,microorganism
Thecommonuseddisinfectantsare
9 Chlorinedioxide.9 Chloramines9 Ozone9 Ultravidetradiaction9 Chlorination.
1Makeashortnoteontheuse&effectofdifferentdisinfectants.
2Drawthelayoutofthewatertreatmentplant.
Nt=Noekt
-
*BrakpointChlorination:Duetothereactivityofchlorine,itreactswitha
multitudeofinorganic&organicmaterialspresentinwater.Insomecases,itis
usedasanoxidizingagentfirsttobreakdownthesematerials.Thistypeof
chlorinationiscalledbreakpointchlorination.Duetohighdosagesofchlorine
normallyemployed,thisprocedureisnolongerperformedinGermany,butstill
widelyusedinUS&othercountries.
:WasteWaterTreatment:
6.1Wastewatercharacteristics:
Wastewatersareeitherfromthesourcofindustrialwastewaterorfrom
municipalwastewater.
Componentsofwastewateraresuspendedsolids,biodegradableorganics,
andpathogens.
Suspendedsolidsareorganicinnature.ExBodywaste,foodwaste,paper&
biologicalcells.
Solubleorganicsinwastewaterareofproteins,carbohydratesandlipids.
Waterbornepathogensmaybefoundindomesticwastewater.
6.2wastewatertreatmentprocesses:
Domestic&industrialwastewatercontainmainlyorganicwaste.
-
So,themaintreatmentprocessesareusedtowardsorganicremoval.
Processare:
9 Pretreatment9 Primarytreatment9 Secondarytreatment9 Advancedtreatment
6.3Pretreatment:
Thefloatingdebrisdestinationproductofbuildingdebris&grit,&oilydictionaryscumsareremovedfromwaste
Vegetationprolentwater,inthepretreatmentprocess
Sometimes,thepHofwastewaterisinsucharangethatwateriseithertooacidicortooalkalineforoptimumbiologicaldegradation.ItneedpHcorrection.ThePHcorrectionisachievedbytheadditionofsulphuricacid(H2SO4)orlime.
6.3.1Screening
Theobjectiveofscreeningistoremovelargefloatingmaterial&soprotectdownstreammechanicalequipments.
9 Corasescreenwithopening(removelargematerial>6mm)
9 Finescreenswithopening(1.6mmto6mmmaterial)(Foractivatedsludge)
9 Veryfinescreenopening(0.2to1.5mm)9 Microscreenwithopening(0.001to0.3mm)
-
Fat,oil,greases
6.3.2Gritchannels
Gritisinorganicsandorgravelparticlesdofsizeabout1mm.
Theyarewashedintosewercollectionsystemsfromroad&pavement.
Gritdoesntexistinindustrialprocessofwastewater.
Gritcanabrademechanicalequipments.
Municipalwastewater
screens
Gritfacilities
FOG
flotation
BalancingpH,
Organic,nutrient
Primarytreatment
-
Gritcollectiondevicesare:
9 Helicalflowaeratedgritchamber9 Horizontalflowgritchannel.
Airentersonesideofchannelnearthebottom&thiscauseaspiralmotionIarto
themainflowdirection.
Airsupply
Grit
FigHelicalflowaerated
gritchannel
Heaviergritparticlessettlewhilethelighterorganicmatter
remaininsuspension.
Aeratedgritchambersaremoreefficientthanhorizontalflow
type.
Thedesignofgritchannelisbasedonsettingofparticle
F1=FD
-
(sw)V=CDAsfw
Sp=Specificgravityofparticiples
CD=dragcoefficient
=
V=Kinematicviscosity
=
Ex12.4Designahorizontalflowgritchambertoremovegritofsize
greaterthan0.2mmifthethroughflowis10,000M3/d.thespecific
gravityoftheparticlesis1.9.
Solution
Settingvelocity(Vs)=.( p w)d2
=x(1.91)x(0.2)2
=19.6mm/see
=0.02m/see
AssumeDepth(D)=1.5xwidth(w)
Vs=(Sp1)d2
-
C/sarea=A=WxD
=1.5w2
A===0.39m2
6.3.3 Flotation : Flotation is usedwhen suspended particles have low setting
velocitythattheyarenotsettleableinsedimentationtank.
Sedimentation, in watertreatment chapter, is the gravity unit process of
separatingsolidsfromliquids.
Flotationisthebuoyancyunitprocessofseparatingsolidparticlesfromaliquid
phase.
Inmunicipalwork,solidsarefats,oils&grases(FOG).
Theprocessof separation involves introducing air bubbles at thebottomof a
flotationtank.
+++++++++++++++++++++++++++++++++++
Fig:DissolvedAirFlotation
Airbubbleattacheswithparticulate(composedofdistunitparticles)dictionary)
matter&thecombinedbuoyancyhelpstheparticletorisetothesurface.Then,itis
removedbyskimming.Dictionary.
-
9 Gravityflotation9 VacuumMakeashortnote9 Electroflotation9 Dissolvedairflotation(DAF)9 Airflotation
6.3.4Equalization:Uniformity/balancing
Wastewater treatment plant receives the waste matter (effluent),
uniformity/balancingisrequiredforthat.
Thisincludes
9 Flowequalization9 Organicequalization9 Nutrientbalancing9 PHbalancing(PHcorrection)
(6.5to8.5)
Flowequalization/balancingoperates&balanced7days.
OverflowRawScreensstructureToprimaryWastewaterGritremovalsedimentation
EqualizationFlowcontrol
1 2 3A
3B 4
-
6.4PrimaryTreatment:
Primarytreatmentisoftencalledclarification,sedimentationorsetting.
Thewastewater isallowed tosettle foraperiod (about2hr) ina setting tank
andproduceclarifiedliquideffluentinonestream.
Therefore, the objective is to produce a suitable for the secondary biological
treatment&achieveasolidseparation.
Hence,theprimarytreatmentinclude
9 Reductioninsuspendedsolids9 ReductioninBOD9 Reductionintheamountofwasteactivatedsludge(WAS)9 Removaloffloatingmaterial.9 Partialequalizationofflowrates&organicload.
++++++++++++++++
FigC/sofatypicalcircularprimaryclarificationtank.
9 Wastewaterentersthroughthediffusionbox.Thetankissizedso,thattheretentiontime isabout2hr. inthisperiod,thesuspendedparticles
settledownassludge&liftupwardsthroughacentralhopper.
6.4.1Chemicallyenhancedprimarysedimentation
Theadditionofcoagulantchemicals
-
(iron,salts,lime,alum)
Beforesedimentationmakesthesuspendedfineparticlesintosettleableflocs.
This process increases. The efficiency of suspended solid & BOD removal
rates.
+++++++++++++++++++++++++++++++++++++++++++++++
Surfaceoverflowratem3/d/m2)
Asthesurfaceoverflowrateincreases,theremovalefficiencydecreases.
Themechanismofchemicallyenhancedprimarysedimentationistousean
aerationtank&addcoagulants.
6.4.2Sludgequantitiesfromprimarysetting:
Theamountofsludgeproducedduringprimarysettingwilldependonthe
totalsuspendedsolids&theefficiencyofsolidremoval.
6.5Secondarytreatment:
Inprimary settingprocess.About60%of suspended solids&30%ofBOD
removedfromwestwater.
Thepurposeofsecondarytreatment is toreducetheBODwhichdoesnot
benefitasmuchassuspendedsolidsfromprimarysetting.
Secondarytreatmentprocessproducesnonpollutingandproductsfromthe
-
(H2O,CO2,Sludge)Biodegradableorganicmatter:
Theendproductshouldntprovideafoodsourceforaerobicbacteria.
(Liquidefficient)
Theremovaloforganicmatterincludestheprocesses:
9 Biodegradation9 Airstripping:removalofcovering9 Adsorption
(accumulation ofmolecules particles to form a thin filmon surface of
water)
9 Activatedsludgesystem9 Attachedgrowthsystem
6.5.1Activatedsludgesystem
Thecommonactivatedsludgesystemsare
9 Completemixreactors.9 Plugflowreactors.9 Oxidationditch9 Contactstabilization9 Sequencingbatchreactors
CompleteMixReactors
-
Ithasuniformcharacteristicsthroughouttheentirereactor.
Aerationisprovidedbysurfaceaerators.
Dissolved oxygen (DO) levels are maintained throughout the process
(2mg/L).
Thereturnedactivatedsludge(RAS)fromtheclarifier is feddirectlytothe
aerationbasin
bacteriaOrganic+O2CO2+NH3+newbiomassOliodProcess
PlugFlowReactors
Plugflowmeansaplugofsubstrateinfluenttoanaerationbasinismoved
forward, without too much interaction with plug. This means satisfacting
mixingoccursinthelateraldirection,butnoneinlongitudinaldirection.
InfluentEffluent
Thereisahighorganicloadingattheinfluentendofthebasin.
Thereisanexcessoffoodsubstrateattheinfluentendshortageoffood
substrateatthedownstreamend.
Throughtheaerationbasinthefoodsubstrate.Decreaseswhilemicro
organismconcentrationincreases.
OxidationDitch
+++++++++++++
Plug
-
FigLayoutofanoxidationditchsystem.
ContactStabilization
Aerationiscarriedoutintwophasesintwodifferenttanks.
Influenteffluent
Sludgesludgewasterecycle,Aeratortank Incontact tank the suspendedorganicmatter isadsorbedby themicrobialmassand
thedissolvedorganicmatterisabsorbedbythebiomass.
Sequencingbatchreactors
Itisacomplexmixactivatedsludgesystemwithoutasecondaryclarifier.
Fivedifferentsequencesarefollowedwithinthesingleaerationbasin.
Aeration&clarificationarecarriedoutinonetank.
++++++++++++++++++++
6.5.2Attachedgrowthsystems(Writeashortnote)
Itallowamicrobiallayertogrowonthesurfaceofthemedia(stone,plastic)
Itexposedtotheatmospherefromwhereitdrawsitsoxygen.
Themicrobiallayerissprayedwiththewastewater.
Contacttank Clarifier
-
Inthisprocess,themicrobiallayerconventsthebiodegradeableorganicwastewaterto
biomass&byproducts.
Microbial:involving/causedbymicrobas
ThemicrobiallayerhelpstoreducetheBODofeffluents.
PercolatingFilters(TrickingFilters)
Thesearegenerallycylindricalorrectangularboxesofconcreteorsteel,containing
stonemedia.
Themediaisangularratherthanrounded(exlimestoneisabetterchoice).
Thefloorofthetankhasanunderdrainsystemforcollectingtheunderdrainsystemfor
collectingthetreatedwastewater.
Q.1Operationoftrickingfilterwithdiagram.
Factorsaffectingtheefficiencyofatrickingfilter.
Granularmediafiltration:
Themediamaynatural/syntheticmedia&filtertypeiseitherofpressureorgranting.
Adsorption:(Activatedcarbonadsorption)
OrganiccompoundmayberemovedbyPACorgranulatedactivatedurban(GAC).Powered.Chemicaltreatment:Inthisprocess,thePHofeffluentrisesto10.811.5,sothat
ammonia(wastewater)
Nitrogenconvertedtoammoniagas&itreleasedtoatmosphere.
++++++++++++++
-
6.6SecondaryClarification:
Theretentiontimeinsecondaryclarificatorisabout2hrssameasinprimaryclarification.Butitisprovidedwithadeepsettingtank.(about4.5m)Theaimisthatnosolidsshouldescapeintheclarifiedeffluent.
Thesolidsarebiologicalinnature.
(Biodegradableorganicmatter)
Itmayrequireoxygendemandfromwaterbodyforthedecomposition.
Theimportantparameterforsecondaryclarificationis
surfaceoverflowrate(SOR)=discharge
AreaofC/S
6.7AdvancedTreatmentProcess(Filtration)
9 Granularmediafiltration:Itcomposedofonetypeofgrains9 Adsorption(Sand/stoneek)9 Chemicaltreatment9 AirstrippingRemovalofammonia;9 Chlorinationwhenammonialevels
arehighineffluent
(wastewater)
6.8WastewaterDisinfection
Theobjectiveofdisinfectionistoeliminatepathogenicorganisms.
Thedisinfectionproducerforwastewaterare?
9 Chlorine9 Ozone
-
9 Chlorinedioxide9 Ultravidetradiation.
6.9Layoutofwastewatertreatmentplant
+++++++++++++++++++++
Figlayoutofatypicalwastewatersystemincludingfiltration.
:Anaerobicdigestion:
Processofdecomposingtheorganicmatter.
7.1Introduction:
Itisusedforthetreatmentofindustrial,agricultural&municipalwastewater.
Anaerobicdigestionistheuseofmicroorganismsforthestabilizationoforganic
(intheabsenceofoxygen)
matterstotheformofmethaneandotherinorganicproducts.
Organicmatter+H2OmicrobialCH4+CO2+
organism
New+NH3+H2S+HeatBiomassItoccursintheabsenceofoxygen.
Concentratedwastewatersledgesmayreactwithwastewater&hena,canproduce
badproductsorgasestotheenvironment.
-
Therefore,Ithastomakethesludgesasinertpriortodisposal.ThecommonNoreaction
withwaterorotherelements.Noreactionwithwaterorotherelements.
Processisbiologicaldegradation.Thisprocessconvertthesolidstononcellularend
products.(dictionary)Notdividedintocells
Theprocessiscommonlytermedassludgedigestion.
2 Sludgedigestionreducesthevolumeofthickensludgeaswellasmakesthe
remainingsolidasinert.
Aerobicdigestion
Anaerobicdigestion
Aerobes:Microorganismsrequireoxygenfortheirsurvival,arecalledaerobes.
Anaerobes:Othermicroorganismscantsurviveintheoxygenenvironment,areknown
asanaerobes.
3 Primarysludgecontainslargeamountsofavailableorganicsthatwouldinducearapidgrowthofbiomassiftreatedaerobically.(dictionary)totalmassoflivingmatter
4 Anaerobicdecompositionproduceslessamountofbiomasscomparedtoaerobicprocesses.
The aim of anaerobic digestion process is to convert as much as sludge to end
productssuchasliquids&gases;whileproducingalittleresidualbiomass.
7.2MicrobiologyofAnaerobicdigestion:
Fourdifferentmicrobiologicalgroups(bacteria)arerecognized.
9 Hydrolytic bacteria compound reacts with water & produce othercompound.
-
9 Acidogenicbacteriaformationofacid.9 AceticlasticMethanogens.9 HydrogenophilicMethanogens.
Proteincarbohydrates.Lipids.HydrolysisProcessHydrologicBacteria.
Acidogenicbacteria
Acidogonesisprocess
Aceticlastic
Complexwaste(sludge)
Aminoacid,sugar Faltyacid,alcohols.
IntermediateProducts.
AcetateH2,CO2
-
BacteriaHydrogenophilicMethanogens
7.3MethaneProclcetion:
Anaerobicsludgedigestiondividesintotwogroups,theacidformers&methane
formers.
Theinfluentsludgeentersthetankclosetothetopatthesupernatantlayer(purified
liquidlayer)
Thereisaactivitydigestingsludgelayerbelowtosupertentlayer.
Finallythedecomposed(digested)sludgestabilizedatthebottomoftank.
Gasreleased.
InfluentsludgeScam
Supernantreleased.
AActivitydigestingsludge.
Stabilizedsludge
Digestedsludge
ExC6H12O63CO2+3CH4
Methane,CO2
-
7.4Applicationofanaerobicdigestion:
Agriculturalwastewatertreatment
Industrial
Municipal
:AirPollution:Mancanhardlysurvivefor5minuteswithoutair.
However,hecansurvive5dayswithoutwater&for5weekswithoutfood.
Whenairgetspolluted,itcausesanumberofdiseasesinhumanbody(animals).
Hence,thepollutedairisharmfultoalltypesoflife(plant,animals).
8.1Airpollutants:
Thepollutedairgetscontactwiththenonlivingmaterials(metal,wood,stoneetc)&
corrosiveactionofpollutedairorduetothechemicalattackofairpollutants.
Primarypollutants
Sulphuroxides(SO2),carbonmonoxide(CO),Nitrogenoxides(NO&NO2),Lead(Pb),
hydrocarbons,allergicagents&radioactivesubstances,H2S,H2F,&methylðyl
mercaptans.
Theprimarypollutantsreactwitheachother&withwatervapour&producesnew
pollutants,calledsecondarypollutants.
Secondarypollutantsareproducedfromhechemicalreactionsduetooxidationcaused
byenergyofsun.
Secondarypollutantsaremoreharmfulthantheoriginalprimarypollutants.
Thepollutantsare:
9 H2SO4(Sulpharicacid)
-
9 Ozone(O3)9 Formaldehydes(HCHO)orCH2O9 Peronyacylnitrate(PAN)(NOz)
1 Sulpherdioxide(SO2)
Itisanirritantgas&wheninhaled,itincreasesthebreathingrate&causesoxygen
deficitinthebody.
exPatientsofasthmaareaffectedbythispollutions.
SO2mayoxidizetoformSO3,whichwheninhaled,maydissolveinbodyfluidtoform
sulphuricacid(H2SO4).H2SO4isaverystrongcorrosiveacid.
SO3causesseverebranchspasm.(dictionary):difficultyinexhalationSO2originatesfromrefineries&chemicalplants,smeltingoperation&burningof
(dictionary):formationmetalsby
heating
fulls.ThermalpowerplantalsoemitsSO2.
ThequantityofSO2inairis0.03ppm
(SpecifiedAirStandard)*
*Contentationofpollutant(Unitofmeasurement)
9 Generallytheconcentrationofpollutantcanbeexpressedasmicrogramspercubismetre(g/m3)atatmospherictemp&pressure.
9 Iftheconcentrationisexpressedincum(m3)permillioncumofair,itiscalledasppm(partspermillion).
9 Therelationbetwnppm&g/m3is:1g/m3=
-
X103
Liter
Molmolecule
( /mol)VolumeinLiteroccupiedbyonemolecule.
2 Carbonmonoxide.(CO)
COhas200timesaffinitytowardsbloodhemoglobin(Hb)thanoxygen.
Wheninhaled,COreplacesO2fromhaemoglobin&formcarboxyhaemoglobin
(COH6).
Ithasnouseinrespiratoryprocess.Hence,helfofthebloodisused
Carbonmonoxideisresponsibleforheartattack.
SourcesCOoriginatesfromautomobileexhausts&incompletecombinationof
organicmatter.(dictionary):(Processinwhich
substancesreactswithoxygen.)
Incities,theconcentrationofCOis54ppm.
Specifiedstandard(9ppm).
3 OxidesofNitrogen(NO,NO2)
NitricoxideNitrogendioxide.
Eye&NasalirritationsarecausesbyNO2(whenconcentrationis15)
Respiratorydiscomfort(concentrationis25ppm)
Itoriginatesfromautomobileexhausts:(dictionary)Furnacesmokes
-
SpecifiedstandardforNO2is0.05ppm
4 HydrogenSulphide(H2S)
H2Sisafoulsmellinggaswithaodourofrottenegg.(dictionary)dirty(dictionary):Damaged/useless
Thisgascauseheadaches,sleeplessness&painineyes.
HigherconcentrationofH2Smayblockoxygentransfer&damagetonervetissues.
H2Sisrarelyfoundinatmosphere,therefore,Itisnotincludedintheairquality
standers.(Nospecifiedstandardconcentration)
Itisproducedinindustrieslikeoilrefinibg,rubber,artificial,silketc.
5 Methyl&EthyleMecaptans
Ethylmercaption:C2H3SH
Thesecompoundsarenotharmfultous.
Theyhavestrongodours.
6 HydrogenFluoride&OtherFluorides
Allfluoridecompoundsareextremelyirritantgas&corrosiveinnature.
Theirsmallerconcentrationmayproducesfluorosisincattle&plants
dictionaryapathologicalcondition.
Itisnotharmfultohumanbeings.
SourcesTheyareemittedintoatmospherefromaluminumplant,steelplant,
phosphatefrtiliserplantsetc&byburningofcoal.
-
Itsconcentrationincityairisveryless(around0.025ppm).Itisnotincludedinair
qualitystandard.
7 Lead(Pb)
SourcesItisejectedintotheatmospherethroughexhaustedofautomobile.(Gasemittedfromtheautomobileengine)Itmaycauseirritationofmucousmucousmembranesofnose,throat&lungs,
when(athinlayerinsideofnose&mouth&outsideofotherpartofbodyinhaledair.
ItmaydamagetoLiver,kidney&gastrointestinaltracts(systems).(dictionary)system.Specifiedstandardforleadinairqualitystandardis1.5g/m3
8 Hydrocarbons(Alkane,Alkene,Alkynes.)
Alkenesarehighlyreactiveinatmospherethroughphotochemicalrealn.
Itreactswithotherpollutantgases&formsnewpollutants.
SourcesHydrocarbonsreleasedtothetmospherebyautomobileexhausts&by
smokesofincinerators&fromOilrefineries.
Hydrocarbonsarefoundtocausebodycancers.
Formaldehydecauseirritationofeyes,skins&lungs.
Airqualitystandardis160g/m3(0.24ppm)
9 AllergicAgents
Microscopicsubstancesinairmaycauseallergicreactionsinhumanbodies,called
aeroallergens.(Physicalmatterofwhichthing/personconsist)
-
Sneezing,asthma,skintroublesareduetoallergicagents.
SourcesItOriginatesfromplants&animals.
Finallypoweredindustrialmaterialsmaycauseallergicreacnwithsensitivepersons.
Poweredlikematerialformseasonalplants.
10RadioactiveIsotopesexTitrium(H3) Carbon11,14,18
Radioactive emissions leads to anemia, cancers & shortening of life spans& geneticeffects.(Itsnuclicareunstable&itdisputeenergybyemittingradiationinthefromof,&rays)&accidentialdischargesfromatomic&nuclearreactors.
11Ozone(O3)
The presence of ozone gas in air may cause irritation in the respiratory (dictionary)tract.System.
itmaybeproducedbyphotochemicalprocess
Twopollutantsunittogetherinthepresenceofsunlight,producingathirdpollutant.
In day time, It is also produced by photochemical realn of hydrocarbons & nitrogenoxide.(inhighlymotorizedareas)vehicleused(dictionary)
Theairstandardforozoneis0.12ppm
Environmentprotectionagency
8.2Criteria&Noncriteriapollutants:
-
Criteriapollutantsare:
9 CO9 NO29 O39 SO29 Lead9 Particlematter(dia
-
Theratewilldiffer fromplacetoplace&fromtimetotime(daytoday)at thesameplace.
Lapserateataparticularplace&timeisdetermined
bysendingabarbonequippedwithathermometer&
aselfrecordingmechanism.
Ambientlapserate/Environmentallapserate
surrounding.
Whenaparcelofair,whichishotter&lighterthanthesurroundingair,isreleased,the
Emittedgases
ittendstoriseup
Untilitreachestoalevel,whereitsowntemperature&densitybecomesequaltothatofsurroundingair.
Therateofdecreaseoftemperaturemaybedifferentthanambientlapserate.ThisiscalledadiabaticLapserate.
Withouttheadditionoflossofheat
2000
Heightin
meter
500
5101520
-
To
EnvironmentalLapserate=
Theemittedgasiscalledplume.(Lapseratevsdisperstmot)pollution
EmittedplumeLoppingplumeLoftyplume
BehaveinNeutralplumefumigatingplume
airunderConingplumeTrappingplume
theseconditions.Fanningplume
8.3.2Impactsofwinds
Themovingairisknownaswind.
Themovementinairisduetounequaldistributionofatmospherictemn&pressureovertheearthssurface&alsobecauseofrotationofearth.
Thedirectionofwindisfromhighpressureareastolowpressurearea.
Quickerheating&coolingofearthcomparedtoseamaycauseflowofair.
9 Daytime(fromseatoland)9 Nighttime(fromlandtosea)
Thismayaffecttotheairpollutionproblemwindspeedismeasuredbyanemometer.
Thevelocityofwindatanyheightzis:
U=Uok
-
WhereU0=windspeedatheightZo
9 K=constforlargelapserate.=(averagevalue)
Thedirection&speedofwindwillinfluencethediffusionofpollutedgases.&emissionofparticulatesfromfactoriesorautomobiles.
unit
8.3.3Impactofpressure
High pressure systems (clear SR/, Light ward condition) cause a bad dispersion ofpollutants.
Lowpressuresystemsleadstogoodmixing&rapiddispersionofpollutions.
8.3.4Impactofmoister
The presence ofmoisture blocks& obstructs the solar radiation reaching to ground,whichaffecttheairquality.
Humidityleadstoformationofdog&increasesthecorrosiveactionofairpollutants.
Excessivemoisture inatmospherewill leadtorain,whichwillbehelpful in improvingthequalityofambientair.
Becauseitwashdownthepollutantstotheearth.
RemovedofatmosphericSO2throughraincauseproblemsduetoreactionofSO2withwater,formingH2SO4.
:Watertreatmentprocess:
Ex.11.3Determinethedailyrequirementofalum,Lime&polyelectrolytetocoagulateaflowof200L/S,ifthejartestindicatesthatqrtimumcoagulationoccurswhen1Litreof
-
waterisdosedwith3mlof10g/Lalumsolution,1.8mlof5g/Lsuspensionoflime&0.2mg/Lofpolyelectrolyte.
AnsCoagulantsaresometimesassistedwithfurtherchemicals,knownascoagulantaids.
Ex1Polyelectrolyte.
Limealkalinityaddition
PHcorrection:Lime,sulphuric,acid(H2SO4)Theamountofchemicalcoagulantpolyelectrolyterequiredforparticularrawwater
qualitycanbedeterminedusinglaboratoryJartest.
Electrolyte:Asolutionthatconductelectrolyte.
transmissionof
electricity
Polyelectrolyte:Aelectrolyteofhighmolecularweight.
Solution1min1hr
Dailyflowrate=200x60x60x24
=17.28x106L1day
Alumrequirement3mLof10g/L
=30mg/Lx17.28x106L
=518.4kg/day
Linerequirement1.8mLof5g/L
=9mg/Lx17.28x106L
=155.5kg/day
Polyelectrolyte=0.2mg/Lx17.28x106L
=3.46kg/day
Ex9.2S.K.Garg
-
The maximum daily demand at a water treatment/purification plant has been
estimatedas12millionlitresperday.Designthedimensionsofasuitablesedimentation
tank for the rawwater supplies, assumingadetensionperiodof6hrs& thevelocityof
flowas20cm/minute.(assumebasinwithinis10m)
Solution
GivenQuantityofwatertreatedin24hrs(daily)
=12x106liters
Quantityofwatertreatedduringdetentionperiod
=(x6)
=3x106litres
=3000cu.m(m3)
Thecapacityoftankrequired=3000m3
Givendata(Velocityofflowtobemaintainedthroughoutthetank)=20
=(0.2)
Lengthoftankrequired=(velocityofflow)xt
(Detentiontime(t)=)Lengthoftank
Velocityoftank
=0.2x6x60
=72matres
C/Sareaoftank=
=
=41.7m2
GivenBasinwidth=10m
Waterdepth==4.17
=4.2m
-
Ex9.6S.K.Garg
In a continuous flow setting tank 3m deep 60m long, what flow velocity of water
wouldyourecommendforeffectiveremovalof0.025mmparticlesat250C.thesp.Gravity
ofparticlesis2.65&kinematicvisocityvforwatermaybetakenas0.01cm2/see
SohtimVs=(Sp1)d2
SettingvelocitydiaofparticlesSp.gravityofparticlesKinematicviscoeity=v = ( s w)d2
So,
Kinematicviscocity
vs=x(2.651)(0.0025)2
vs=0.0562
Settingvelocity
InletAD
Depthof(=H)
water
sludgezone
Vs=(sp1)d2
-
V=flowvelocityinhorizontaldirect
Vs=settingvelocity
FromthevectordiagramfromAtoC,wecanwrite.
Flowvelocity
V=)xVs
=x0.0562
=1.35cm/see.
Derivationofstokeslaw:
Vs=(Sp1)
Kinematicvisocityofwater(m2/see)
Sp=Sp.Growthofparticle
F1F1=Impellingfor=densityofparticle
FDFD=Dragforcedensityofwater
Dragforceincreaseswithincreaseofvelocity,tillitbecomesequaltoeffectiveweightofparticlei.e.(V=Vs)
Effectiveweightofparticle(F1)
=TotalweightBuoyancy
=)ys)yw
-
VolumeVolumeofsperialparticle
=r3(VsVa)
Unitwt.ofwater
Unitweightofparticle
=(
Dragforce(FD)
(Areaofparticle)(r2)=CDAs.Pw.
CD=dragcolt.
=
=0.4(forsphericalparticles)
V=dynamicvisocityofwaterdensityinkg/m3(m2/see)
F1=FDVs=Vs=
WhereSp=V=*Dragforcereferstoforcesactingoppositetotherelativemotionofanyobjectmoving
withrespecttothesurroundingfluid.
:NoisePollution:
9.1Introduction:
(Sp1)
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Noiseisdefinedasanunwantedsound.Theunwantedsoundproducesseveral
undesirableeffectsonourbodyhealth,therefore,itcanbecalledasapollutant.
Itinterfereswithonesactivitieslikework,rest,sleepetc.&producesundesirable
physiological&psychologicaleffectsinbody.
Itismainlyinhighlyindustrializedcountries,characterizedbyhighvolumeoftraffic;&
sportingactivities&lowflyingaireaftetc.
Itreducesthequalityoflife&causesasignificanthealthhazard.
Ex1)Peoplelivingadjacenttobusyroadtendtohavehigherbloodpressure.
2)Highnoiselevelsofsufficientdurationcanresulttemporary/permanenthearingloss.
3)Irritation,headacheetc.
9.2Physicalpropertiesofsound:
Soundisproducedintheenvironmentbyalternatingpressurechangesintheair
becauseofvibrationsofsolidobjects.orseparationoffluids.
Alternatingpressurevariationproducessoundwaveswhichpropagateintheformof
sinusoidalwavepattern/cosinewavepattern.
T
A
(+ve)
SoundPressure
(ve)T
A=Amplitude
T=Wavelength=Distmabetwntwosuccessivecrests.
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Timeperiod:Thetimerequiredforacompleterotationoscillation
Frequency:Thenoofcompletedcyclesperunittime.
Mostsoundsarenotpurelysinusoided.Theyvarybothinfrequency&magnitude.
Soundpressure(Prms)
Rootmeansqure.
=(P2)=1/2
(P=pressureateachinstantoftime.)
Soundpower&intensity
Therateatwhichenergyistransmittedbysoundwavesiscalledthesoundpower(W)
measuredinwatt.
Theaveragesoundpowerperunitareanormaltothedirectionofpropagationofa
soundwaveistermedthesoundintensity.
I=Wetts/m2metre.
I=soundintensity/acousticintensityatadistancerfromthesoundwave.
9.3Noisecriteria:
Loudnessofasoundisdeterminedbyitssoundpressurelevel&frequency.
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9.4Noisestandard:(x)
Soundpowerisindifferentrange.
Deeibel:Soundpowerlevelismeasuredindecibel(db).Itisthereferencepowerlevel;
1012watts(db).
Soundpower(watts)
Soundpowerlevelindb
9.5 Noisemeasurement:
Soundpowercantbemeasureddirectly,whereassoundintensitycanbemeasured
withmoderninstrumentation.
9 Soundlevelmeter.(Readthe
Lw=10log10
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9.6Noisecontrol:
Whennoiselevelisexcessive,thesolutioninvolvesthreesteps.
(a) SourceSourcecouldbemodifiedbythetreatmenttomachinesurfaces.
(b) TransmissionpathCouldbemodifiedbycontainingthesource(machine)insidea
soundinsulatorandbyconstructinganoisebarrio(absorbingmaterial)
(c) ReceiverProtectionofthereceiver(ear)byprovidingearprotection.
Soundprotectioninbuilding
Externalsoundwillenterabuildingthroughtheweakesttransmissionpath.(maybewindow)Whensoundpressurewavemeetawall/buildingsurface,thebuildingvibrates&
soundisradiatedbuckintospace.
Partofsoundenergyisreflected,partisabsorbedbysurface&remainderis
transmitted.
Vibrationwillbelargeratthenaturalfromofelement(will/building).
Naturalfromdependsonweight,surfacearea&rigidityofbuildingelement.
Soundreductionisbetterforhighernaturalfrequency
:10.SolidWasteManagement:
10.1Introduction:
Solidwastesincludepaper,plastics,glass,foodwaste,ashetc.italsoinclude
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paints,oldmedicines,etc.liquidwates
Fromhealthpointofview,solidwastesare
9 Humanpathogens(exHandkerchiefs,contaminatedfood&surgicaldressing)
9 Animalpathogens(exWastefrompets)9 Soilpathogens(exGardenwaste)
10.2Sources&classification
Solidwaste/municipalsolidwasteiscollectedfromdomestic,commercial&industrial
sources.
SourceTypesofwaste
Domestic(Singlefamilyhouse,Food,paper,packaging,glass
MultiFamilyhouse.Low,medicinemetal,ashes.
&highriseapartments)otherhouseholdwaste
Commercial(shop,restaurants,Types
Markets,office,Food,paper,
Buildings,hotelsPackaging,glass,
&institutions)metals,ashes.
(sameasdomestic)
Industrial(Fabrication,Types
Manufacturing,refineries,Industrial,process
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chemicalplants,miningwastes,oil,metal,plasticsetc.
Construction&demolition.Soil,concrete,
(destruction)timber,steel,
Plastics,glass.
10.3CompositionofMSW:
Municipalsolidwaste.
Thebasicideaistoidentifywasteasbeingorganicornonorganic(Inorganic).
Organic:Food,vegetables,paper,
Cardboard,plastics,
Clothing,gardenwaste,
Wood,bone.
Inorganic:Metals,glassash,
Stone,brick,etc.
WHO(Worldhealthorganization,1991)
Categorytheindustrialwasteintothreetypes:
9 Nonhazardousindustrialwaste.9 Hazardouswaste.9 Hospitalwaste.
10.4PropertiesofMSN:
Wastehandlersneednttoknowthephysical,
Chemical&biologicalpropertiesofsolidwaste.
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Forproperwastemanagement(disposal,transformation,reuse&recycling),wehavetoknowthephysical,chemical&biologicalpropertiesofsolidwaste.
Physicalpropertiesare:
9 Density&moisturecontent(kg/m3)9 Particlesizedistribution.(mm)
(LxBxH)9 Fieldcapacity(%)metre9 Hydraulicconductivity(m/day)9 Shearstrength(KN/m2)
Fieldcapacityisthemaximumpercentageofvolumetricsoilmoisturethatasoilsamplewillholdfreelyagainstgravity.
Density&moisturecontentofMSWisabout20040kg/m3&is1sto40%forthecompaction(density)(moisture)
Ofsoildswasteinlandfill.
Hydrauliccontectingistherateofmovementofwaterintosoil.Sludgeresiststhemovementofwarterdownthroughthesolidwaste.
Densewaste:7x106m/s/Loosewaste:15x1015M/S
Filedcapacity=0.60.55
W=Overburdenweightofsolidwasteinlift.
ShearstrengthofsludgeinLandfillisaboutzero.
Hardness:isdefinedastheconcentrationofmultivalentmetalliccationsInsolution.
Organics:Thesearecarboncompoundproducts.
Biodegradableorganic
Nonbiodegradableorganic
Biodegradableorganic:Materialscanbecetilizedforfoodbynaturallyoccurringmicroorganizations.Thesematerialsconsistsofstarches,facts,proteins,alcohols,acidetc.
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NonbiodegradableOrganics:Someorganicmaterialshavetheresistanttobiologicaldegradation.
Aeration:Itisaprocessusedinpreparingthepotablewater.
(drinking)
9 ItmaybeusedtoremoveundesirablegasesdissolvedinwaterBiochemicalprocess:Thesechemicalreactionsarenotspontaneousbutrequireexternalsourceofenergyforinitiation.
Turbidity:isameasureoftheextenttowhichLightiseitherabsorbedorscatteredbysuspendedmaterialinwater.
Itisnotaquantitativemeasurementofsuspendedmaterial.
Sp.Gravity:Thedensityofasubstmee/particlerelativetothedensityofwater.
Effluent:Watermixedwithwastematter
Viscocity:Resistanceofliquidtoshearforceinflow.
PH:Potentialofhydrogen(Logarithmofthereciprocalofhydrogenionconcentrationingmatomsperlitre).
Diffusion:themovementofasubstancefromanareaofhighconcentrationofthatsubstancetoanareaoflowerconcentration.Sludge:theprecipateproducedbysewagetreatment.
Sewage:wastemattercarriedawayinsewers
Decant:Causetoflowoutfromacontainer.
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.4 PropertiesofMSW:MostoftheMSWwasdumpedsoitnotnecessarytofindthechemicalproperties.Sincerecycle,reuse&transformationtechnologyfollowed,wearedeterminingthechemicalpropertiesof
MSW.ChemicalPropertiesTechnology/Analysisprocessusedtofindthechemicalpropertiesas:
9 Proximateanalysis9 Ultimate9 Energycontent.
Proximateanalysisinclude
(a) Moisturecontentbypercentageweight(b) Voletinematter(c) Fixedcarbon(d) Noncombustiblefraction(ash).
Theenergycontentisbasedinheatvalue.
Heatenergyproduced,itthe
Solidwasteisburnt
(Joule/kg)/orMI/kg
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(Hu)=(HawfxB2.445xw)
Easilyburning
B=Flammablefraction.(%)
(Volatilematter+fixedcarbon)
W=moisturecontentfractionbyweight(%)
Ultimateanalysisisfollowedtoknowtheenergyproducedbycombustionorbiologicaltransformationofsolidwaste.
1)
(Dulongequation)
WhereC,
Ultimateanalysisincludethe%oftheaboveelement.
2) Khanetal(1991)
E=0.051
Energycontentin F=%offrombyweightCP=%ofcarboard&paperbyweight.
PLR=%ofplastic&rubberbyweight.
BiologicalpropertiesDuetoaerobic/anerobicdigestion,solidwasteistransformedintoenergy&otherendproducts.
Anerobicdigestionprocessisresponsibleforthedecompositionoffoodwastestoendproductmethane,Thesolidwaterrelatedtobiodegradation.AreOil,fat,proteins,celluloseetc.Therefore,thebiodegradationoffoodfractionofMSWisdeterminedby
Lignincontent(%)Biodegradationfractionexpressedonavolatilesolidbasic.
LCLignincontent(dryweight)ofVolatilesolid.
LigninAcomplexpolymerconstituteofwood
otherthancarbohydrate.
BF=0.830.028LC
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VolatileSubstancethatchangesreadilyfromsolid/liquidto
vapouratnormaltemperature.
Dispose:toarrangethings/orpeopleinaparticularway/position.
Disposal:theactofgettingridof5th.
tobefreeofsb/thing
thathasbeenannoyingyou
haulier:aperson/companywhosebusinessistransportinggoodsbyroads/railways.
10.5 Separation:
Separationofdifferentfractionofwastefromthetotalsolidwastecanbedoneatsource(household/orindustry)oratfinaldestination.
Basedonseparation,thetotalMSWisdividedinto:
9 Wastesthataredesirablyseparatedatsource9 Allotherhouseholdwaste.
Wastesthataredesirableseparatedatsource
(sourceseparation)
9 Foodwaste9 Paper&cardboard9 Plasticaverythickpaper9 Metals9 Glass.
Otherhouseholdwastesare
9 Bulkywaste(tyres,furnitureetc)9 Hazardoushouseholdwaste.9 Yardwaste.
Anareaoutsideabuilding(withasurroundingwell)
10.6) Storage&transportofMSW:
Differenttypes&sizesofstoragecontainersareusedforMSW.
Therangeforsizevaryfrom25Lcapacityto40000litre.
Forapartmentbuilding,thesizeofcontainerisfrom600to1000Litre.
Thetypesofstoragedependonthecollectionfacility.
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9 Haulierforbulkyitems.aperson/companywhosebusinessistransportinggoodsbyroad/railways.
9 Doorstepcollection(areaveryclosetodoor.)
9 Regularkerbcollection(sideofroad)
9 Vacuumtrucketc.(emptyspace)
Typesofstoragesareplasticbag,wheeled,bin,vaccum,truck,paperbagetc.
(alargecontainerwithacover/aid)
10.7) MSWManagement:
Thetechnologiesusedfortreatment&disposalofMSWare:
9 Wasteminimization9 Reuse&recycling9 Biologicaltreatment9 Thermaltreatment(combination/incineraton)9 Landfiling
10.8) Wasteminimization:
Itfollowsthereductioninamountofsolidwastegeneratedatsources.
Examplesofsourcesare:
1 Productionunitsforfood&householdproducts.(Industry)
2 Productionunitsforcommercialproducts.3 Shoppingoutlets(Businessplace)4 Households5 Office,institutes&commercialproperties.
10.9) Reuse&Recycling:
Aluminiumcansareconsideredforrecyclingpurpose.
(dictionary)container
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Paper&cardboardareusedasarecyclingsolidwastematerial.
Glasswaswellrecycled.
Exdifferenttypesofbottles.
Plasticsaremostlynonbiodegradable.
Hence,itisundesirableinlandfilling.
Therefore,plasticsarerecycled.
Yardwaste,organicfoodfractionetc.
10.10)BiologicalTreatment:
9 AerobicorcompostingItisanaerobicprocessWhichdecomposetheorganic
foodwaste.9 AnaerobicorBiogas9 Combinedanaerobivc&aerobic
1 Compostingisanaerobicprocesswheremicroorganismsdecomposetheorganicfoodwasteinanoxygenenvironment.
aerobicbacteria
Organicmatter+O2Newcells+CO2+H2O+NH2+SO4
Thefinalproduct(compost)consistsofminerals&complexorganicmaterial.
Therequiredparametersforthecompostingprocessare:
9 Temperature*9 Moisturecontent(%)9 Oxygen(%ofoxygen)9 (range68)9 Biochemicalcomposition
(Itinfluencestheprocessrate)
2 Anaerobicdigestion(Absenceofoxygen)
Organicmatter+H2ONewcells+CO2+CH4+NH3+H2S
anaerobicbacteria
ThebeneficialendproductistheCH4(methane).
ThisprocessdecomposethefoodwastetoCH4.
3 Combinedanaerobic&aerobicprocess
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Anaerobicdigestionfollowedbyinvesselaerobiccomposting.
(1stprocess) (2ndprocess)
10.11)ThermalTreatment:
Thermaldegradationoforganicmaterialcanbecarriedoutwith/withoutoxygen.
Thermaldegradationwithexcessoxygeniscalledcombustion.
Whenthefuelisawaste,thethermaldegradationprocessiscalledincineration.
IncinerationOrganicmaterialisconvertedintoheatenergy,gas,slag.
10.12)Landfill:
*Aschematic(Layout)oflandfillprocess.
:11HazardousWasteTreatment:
11.1) Hazardouswaste&itsgeneration:
Hazardouswastemeans
9 Itcausesfire(Ignitable)9 Itreactswithother(reactive)9 Itdestroy/corrodeother(corrosive)
Tissue/material9 Solidwasteisdangertohealth.(toxic)
Itpollutewater,food&air
Itmaybemedicalhazardouswaste.
orhouseholdhazardouswasteorfromindustry.
Examples
Copper(Cu),Zine(Zn),Lead(Pb)&
Mercury(Hg)etc.
Lubricatingoil,drillingoil,syntheticoil
NO2,Organics,hydrocarbons,etc.
TaskWriteexamplesofhazard/solidwastesfrommedical/household/industry.
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11.2 TreatmentforHazardousWaste:
*Incineration
Hazardouswastecanbemanaged/treatedbyincineration/Landfillingprocess.
Intheincinerator,thewasteisoxidizedinanoxygenrichenvironmentatelevatedtemperature.
Themostimportantcriteriaforhazardouswasteincineratorsisthecompletedestructionofthemajorhazardouscompounds.
Thecombustionefficiency(CE)iscalculatedas:
Where
Incinerationisacontrolledhightempratureoxidationofprimarilyorganiccompoundtoproducecarbondioxide&water.
OrganicwasteIncinerationCO2+H2O+Byprotein
Thenetheatvalue(NHV)forwasteinincinerationprocessis
NHV=1.25(T15)x
[1+0.268(NHV+EA)]
WhereT=(therequiredtemperatureforincineration,OC)
=15+
EA=Heatcapacityofexcesssirof1.25KJ/Kg.OC
Duringincineration,heattransferoccurredbyconduction,convection& radiation.(lowtempn)
at(hightempn)
Energyspreadsintheformofwaverays.
Convection:transferofheat Conduction:transmissionofheat
throughfluid(liquid&gas)(transferfromonemediumtoanothermedium.)
Typesofincinerators
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Incineratortypedependsonageofstructure&economics.
9 Rotarykiln9 Liquidinjectionfor(liquidorganicwaste)9 Plasmaarcelectricalconductionthroughagas9 Wetairoxidation9 Fluidizedbed.
Theuseofanelectricalarcforwastetreatmentgenerallyitisusedwithinchemical&metallurgicalindustryastooltoprovidehightemperature.(280000C)
Wetoxidationisanaqueousphaseoxidationwhereorganic&inorganicmaterialssuspendedordissolvedinwateeareexposedtooxygen/(gaseoussource).
11.3) Handlingoftreatmentplantresidences:
Residuefromincineratorare:
9 Slagfromrotarykiln9 Dustfromheatboiler9 Reactionendproducts
Residuefrominorganicplantare:
9 Filtercakes9 Wastewater
Theabovewastesrequirefurthertreatment.
*Securelandgfill*Stabilization(solidification)
SecureLandfill
Securelandfillarethedisposalsitesforfiltercakes,slag,dustfromafulltreatmentfacility(treatmentplant).
ThedesignofasecurelandfillissimilartothatMSWlandfill.
9 SiteLocation9 Designoflandfill9 Constructionoflandfill9 Operation
Stabilization(Solidification)
WhenhazardoussolidwasteisnottreatedbyLandfillingprocess,stabilizationisthenextchoiceforfurthertreatment.
Allingredientsaremixedinacontinuousmixter
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Wasteacid
Batchreacts
SolidationPlant
11.2 Treatmentforhazardouswaste(Continued)
1 RotaryKiln
Rotarykilnisusedinthecement,lime,clay,iron,coal&phosphateindustry.
Traditionalcementkilnsarenowchoosenashazardouswasteincinerators.
Rotarykilnprovidetheprocessesforincineration
9 Mixingofsolids9 Containmentofheatforheatexchange.(cantspread)/topreventaccidentalrecycle
ofradioactivematerial.
9 Chemicalreaction
Blastfurnaceash
WasteSolid(or)
sladgeCement Water
Contineousmixer
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Rotarykilnsarecapabletotreatbulksolids,sledges,liquidsetc.
2 Liquidinjectionincineration
ItisusuallyusedtoidealLiquidwastestreamscontainingminor
concentrationoforganiccontaminants.makesimpure
(substancethatcontaminates)
InLiquidinjectionincinerator,thewastedontcontainthenecessaryheatvaluetosustainitsowncombustion.
10.12MSWLandfill:
ThetraditionalmethodofdisposingofMSWisLandfill.
ThedesignofLandfill&secureLandfillsaresimilarinnature.
ParameterfordesignofLandfilltosatisfyimpermeabilityinmaterial(generallyconcock).
&topreventleahate(PenetrationofLiquidthroughthematerial).
LandfillDesign:
1) Foundationdesign2) Linerdesign(Toavoidseepageofleachete.)
Aprotectingcoverthatconstructsinsideoflandfilltoprotectthesurface.
3) Leachatecollection&gascollection.(Lechate&Landfillgasisreleased)
4) Drainagedesign5) Fillingdesign6) Runoffcollectionsurfacewelfer7) Closuredesign
ReactionsInLandfill
Gascollection
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(Liquidwaste)
Leachateisthecontaminatedwaterinlandfill,whichproductsthroughexternalprecipitation.
(makeharmful/impure)
LandfillOperation:
wasteitems,Loads,typeetc.
(solid,liquid)
(organic/inorganic)
Cell/compartmentforhazardouswaste.
Cell/compartmentfornonhazardouswaste.
Landfilltypes:
Landfillsaretwotypes1)Attentuate&dispersesites.
tomake5thweaker.
2)Containmentsites.Attenuate&dispersesites
Leachatedisperses/spreadsthrough
OldPores&fissuresintotheunderlyingsaturatedzone.Type
Newlandfillsarecontainmentsites.Leachate&Landfillgasarecollectedwithspecialdesignprocedure,whichisisolatedfromthesurroundingenvironment.
Leachatecollection
Lechatetreatment
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:EnvironmentalImpactAssessment:
12.1Introduction:
EIAisaprocessthatrequiresenvironmental&publicparticipationinthedecisionmakingprocess
ofprojectdevelopment.
EIAincludesthefollowingprocedures:
9 Screening(Todecidewhichprojectshouldbesubjecttoenvironmentassessment.)
9 Scoping(Issuesshouldbeincludedinenvironmentalassessment)9 EISpreparation(Scientific&objectiveanalysisofpreparationof
documentation.)
Environmental1ReviewMethodsdevelopedImpactstatementtoassiststhetask.
Defuissurveyistobetakenbyagovernmentorganization/agency.Thereviewpanelguidesthestudy&thenadvicesthedecisionmakers.
Wetairoxidation:(continuingfrompreviouspages)Air/oxygen
(coolingwater)
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Heatexchanger.
Thetemperatureofoperationisfrom150to3250C&operationalpressureisfrom2000
kpato20,000kpa
Theprocessisitcarriesinabatchreactor.
Batchreactor:Itconsistsofatankwithmovingorshakingfacility&auditionedheating&
coolingsystem.Avarietyofoperationsuchasmixing,dissolution.chemicalreach&crystulization
canbedoneinsidethebatchreactor.
Due tohighpressure&high temperature, the constructionmaterial of reactor.Must
havetheresistancetowardscorrosiveactionofhazardoceswaste.
An extentwaterbased cooling system is provided. If thewaste is in suspension, it is
directlypumpedintothereactor.
Duringtreatmentinahorizontalreactor,oxygen/airareinjectedatcertainpositioninto
thereactor.Acontinuousoxidationtakesplace&majorityoftheorganiccompoundsareoxidized.
FluidizedBedCombustion:Consistsof
9 Airfluidizationsystem9 Bedmaterial9 Fluidizedbedvessel9 Wastefeedsystem9 Fluegascleaningequipment.