Part 1 Aerobic Treatment of Wastewater

8/10/2019 Part 1 Aerobic Treatment of Wastewater

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NDWRCDP Disclaimer NDWRCDP Disclaimer This work was supported by the National Decentralized WaterThis work was supported by the National Decentralized WaterResources Capacity Development Project (NDWRCDP) withResources Capacity Development Project (NDWRCDP) with

funding provided by the U.S. Environmental Protection Agencyfunding provided by the U.S. Environmental Protection Agencythrough a Cooperative Agreement (EPA No. CR827881through a Cooperative Agreement (EPA No. CR827881 --0101 --0)0)

with Washington University in St. Louis. These materials havewith Washington University in St. Louis. These materials havenot been reviewed by the U.S. Environmental Protectionnot been reviewed by the U.S. Environmental Protection

Agency. These materials have been reviewed by Agency. These materials have been reviewed by

representatives of the NDWRCDP. The contentsrepresentatives of the NDWRCDP. The contentsof these materials do not necessarily reflect the views andof these materials do not necessarily reflect the views andpolicies of the NDWRCDP, Washington University, or the U.S.policies of the NDWRCDP, Washington University, or the U.S.

Environmental Protection Agency, nor does the mention of tradeEnvironmental Protection Agency, nor does the mention of tradenames or commercial products constitute their endorsement ornames or commercial products constitute their endorsement or

recommendation for use.recommendation for use.


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CIDWT/University Disclaimer CIDWT/University Disclaimer

These materials are the collective effort of individuals fromThese materials are the collective effort of individuals fromacademic, regulatory, and private sectors of theacademic, regulatory, and private sectors of the

onsite/decentralized wastewater industry. These materials haveonsite/decentralized wastewater industry. These materials havebeen peer been peer --reviewed and represent the current state ofreviewed and represent the current state of

knowledge/science in this field. They were developed through aknowledge/science in this field. They were developed through aseries of writing and review meetings with the goal of formulatiseries of writing and review meetings with the goal of formulati ngnga consensus on the materials presented. These materials do nota consensus on the materials presented. These materials do not

necessarily reflect the views and policies of University ofnecessarily reflect the views and policies of University of Arkansas, and/or the Consortium of Institutes for Decentralized Arkansas, and/or the Consortium of Institutes for DecentralizedWastewater Treatment (CIDWT). The mention of trade names orWastewater Treatment (CIDWT). The mention of trade names or

commercial products does not constitute an endorsement orcommercial products does not constitute an endorsement orrecommendation for use from these individuals or entities, norrecommendation for use from these individuals or entities, nor

does it constitute criticism for similar ones not mentioned.does it constitute criticism for similar ones not mentioned.


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CitationCitation

Seabloom, R.W. and J.R Buchanan. 2005. AerobicSeabloom, R.W. and J.R Buchanan. 2005. Aerobic

Treatment of WastewaterTreatment of Wastewater PowerPointPowerPointPresentation.Presentation. inin (M.A. Gross and N.E. Deal,(M.A. Gross and N.E. Deal,eds.) University Curriculum Development foreds.) University Curriculum Development for

Decentralized Wastewater Management.Decentralized Wastewater Management.National Decentralized Water ResourcesNational Decentralized Water ResourcesCapacity Development Project. University ofCapacity Development Project. University of

Arkansas, Fayetteville, AR. Arkansas, Fayetteville, AR.


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Aerobic Treatment of Aerobic Treatment of

Wastewater Wastewater ObjectivesObjectives

review of how aerobic microorganisms canreview of how aerobic microorganisms canbiochemically oxidize soluble and colloidalbiochemically oxidize soluble and colloidalorganic compounds, and how nitrogenousorganic compounds, and how nitrogenouscompounds are oxidizes into nitrate.compounds are oxidizes into nitrate.review the processes that create an oxygenreview the processes that create an oxygen

demand and how aeration can be provide todemand and how aeration can be provide tomeet the oxygen demandmeet the oxygen demand


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Primary GoalPrimary GoalUse aerobic microorganisms to provideUse aerobic microorganisms to providesecondary treatment to domesticsecondary treatment to domesticwastewater wastewater

secondary treatment focuses on the removalsecondary treatment focuses on the removal

of biodegradable organics and suspendedof biodegradable organics and suspendedsolidssolidsusually accomplished with biological reactorsusually accomplished with biological reactors

Biodegradable organics must be removedBiodegradable organics must be removedfrom wastewater stream to minimize thefrom wastewater stream to minimize the

impact on the subsequent processesimpact on the subsequent processes


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Biochemical Oxygen DemandBiochemical Oxygen Demand(BOD)(BOD)

Mass of Dissolved Oxygen Consumed byMass of Dissolved Oxygen Consumed by Aerobic Microbes while Biodegrading Aerobic Microbes while BiodegradingOrganic Compounds and while ConvertingOrganic Compounds and while Converting

Ammonium to Nitrate Ammonium to Nitratea measure of the potential impact a pollutanta measure of the potential impact a pollutant

may have on a receiving streammay have on a receiving streama higha high --BOD waste will cause the consumptionBOD waste will cause the consumptionof dissolved oxygen out of the water at aof dissolved oxygen out of the water at agreater rate than natural aeration.greater rate than natural aeration.


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BOD NomenclatureBOD NomenclaturecBODcBOD

Carbonaceous BODCarbonaceous BOD oxygen demand due to carbon oxidationoxygen demand due to carbon oxidation usually reported as BODusually reported as BOD 55 and potential nitrificationand potential nitrification

is suppressed during measurementis suppressed during measurement

nBODnBODNitrogenous BODNitrogenous BOD

oxygen demand due to nitrogen oxidationoxygen demand due to nitrogen oxidationuBODuBOD

Ultimate BODUltimate BOD oxygen demand measured over long time periodsoxygen demand measured over long time periods


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Oxygen Demand with TimeOxygen Demand with Time

From Academic Curriculum chapter: Onsite Nitrogen Removal, By Stewart Oakley


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Organics, Microbes & OxygenOrganics, Microbes & Oxygen

Bioavailable organic compounds provideBioavailable organic compounds provide

food and energy to microbesfood and energy to microbesnaturallynaturally --occurring microorganisms consumeoccurring microorganisms consumefood, and create more microorganismsfood, and create more microorganismsthe more microorganisms, the more foodthe more microorganisms, the more foodconsumedconsumed

the more food consumed, more dissolvedthe more food consumed, more dissolvedoxygen is requiredoxygen is required


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Basic EquationBasic Equation -- CarbonCarbon

2 2 2

aerobicmicroorganismsOrganic Carbon + O Energy + CO + H O + Residue

2 2 2new aerobic

microorganisms+ O Energy + CO + H O + Residue

2 2 2new aerobicmicroorganisms+ O Energy + CO + H O + Residue


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Biological NitrificationBiological Nitrification

Organically bound nitrogen is released whenOrganically bound nitrogen is released when

the organic compound is oxidizedthe organic compound is oxidizedreleased as the ammonium cation (NHreleased as the ammonium cation (NH 44 ++))Nitrification is a twoNitrification is a two --step autotrophic processstep autotrophic process

the conversion from ammonium to nitratethe conversion from ammonium to nitrate

Nitrosomonas NitrosomonasStep 1:Step 1: NHNH 44++ + 3/2O+ 3/2O 22 NONO 2222-- + 2H+ 2H ++ + H+ H 22OO

Nitrobacter Nitrobacter Step 2:Step 2: NONO 22-- + 1/2O+ 1/2O 22 NONO 33--



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Biological NitrificationBiological NitrificationDuring this energy yielding reactionDuring this energy yielding reaction

some of the NHsome of the NH 44++

is synthesized into cellis synthesized into celltissue giving the following overall oxidationtissue giving the following overall oxidationand synthesis reaction:and synthesis reaction:

Nitrifiers use CONitrifiers use CO 22 instead of organic carboninstead of organic carbonas their carbon source for cell synthesis andas their carbon source for cell synthesis and

for the conversion of NHfor the conversion of NH 44 ++ to NOto NO 33 ----N.N.

Autotrophic Autotrophic1.00NH1.00NH ++ + 1.89O+ 1.89O 22 + 0.08CO+ 0.08CO 22 0.98NO0.98NO 33-- + 0.016C+ 0.016C 55HH77OO22 N + 0.95H N + 0.95H 22O + 1.98HO + 1.98H ++

Bacteria Bacteria new bacterial cellsnew bacterial cells



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Overall, the Result.Overall, the Result.

If Dissolved Oxygen is Consumed FasterIf Dissolved Oxygen is Consumed Faster

than Aeration, then Anaerobic Conditionsthan Aeration, then Anaerobic ConditionsOccur Occur

anaerobic microbes will continue theanaerobic microbes will continue thedegradation processdegradation process

but at a much slower rate than aerobic microbesbut at a much slower rate than aerobic microbes aquatic species that depend on dissolved oxygen willaquatic species that depend on dissolved oxygen will

either move or perisheither move or perish

aquatic species that cannot survive underaquatic species that cannot survive under

anaerobic conditions add to the excessanaerobic conditions add to the excessorganic matter in the systemorganic matter in the system


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Thus,Thus,

BOD can be used as a measure ofBOD can be used as a measure of

wastewater strengthwastewater strengtha high BOD suggests that the organica high BOD suggests that the organiccompounds are easily biodegradablecompounds are easily biodegradableindicates the mass of dissolved oxygen thatindicates the mass of dissolved oxygen thatcould be removed by aerobic microbescould be removed by aerobic microbes

SecondarySecondary --treatment devices reduce thetreatment devices reduce theoxygen demand of a wastewater oxygen demand of a wastewater


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Providing Dissolved OxygenProviding Dissolved Oxygen

Aerobic treatment Systems take Aerobic treatment Systems take

advantage of this Natural Process byadvantage of this Natural Process byProviding Plenty of DOProviding Plenty of DO

highhigh --rate carbon removal and ammonificationrate carbon removal and ammonificationoccupies a smalloccupies a small --footprintfootprintrequires energy to maximize oxygen transfer requires energy to maximize oxygen transfer

biological reactor biological reactor


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Microbes as WorkhorsesMicrobes as Workhorses

Microorganisms are usedMicroorganisms are used

to convert colloidal and dissolvedto convert colloidal and dissolvedcarbonaceous organic matter into variouscarbonaceous organic matter into variousgases and into cell tissuegases and into cell tissue

gases evolve (CO2, N2, and others)gases evolve (CO2, N2, and others) new cells can be settlednew cells can be settled thus carbon is removedthus carbon is removed

break other nutrients out of organicbreak other nutrients out of organiccompoundscompounds nitrogenous compoundsnitrogenous compounds

phosphorus speciesphosphorus species


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Optimizing a Natural ProcessOptimizing a Natural Process

Bioreactors are built to maximize theBioreactors are built to maximize the

production of beneficial endproduction of beneficial end --productsproductsalcohols (beer)alcohols (beer)insulininsulinother medicationsother medications

And Andconvert wastewater into secondaryconvert wastewater into secondary --qualityqualityeffluenteffluent


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Wastewater TreatmentWastewater Treatment

Examples of Aerobic Bioreactors used forExamples of Aerobic Bioreactors used for

Secondary TreatmentSecondary Treatmentactivated sludge plantsactivated sludge plantsrotating biological contactorsrotating biological contactorspackedpacked --bed media filtersbed media filters

HighlyHighly --Engineered Systems that UtilizeEngineered Systems that UtilizeMicrobial Metabolism to Convert OrganicMicrobial Metabolism to Convert OrganicCompounds into Cells and Carbon DioxideCompounds into Cells and Carbon Dioxide


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Microbial MetabolismMicrobial Metabolism

Chemical Activities Performed by CellsChemical Activities Performed by Cells

CatabolismCatabolism biochemical process that degrades substratebiochemical process that degrades substrate

(food) down to end(food) down to end --products with the release ofproducts with the release of

energyenergy energy is held in chemical form for future useenergy is held in chemical form for future use

Anabolism Anabolism biochemical process that synthesizes new cells.biochemical process that synthesizes new cells. energy from catabolism is used to drive theenergy from catabolism is used to drive the

processprocess


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CatabolismCatabolismFermentationFermentation

first step in biodegradationfirst step in biodegradation

does not depend on presence of oxygendoes not depend on presence of oxygenboth aerobic and anaerobic microbes use thisboth aerobic and anaerobic microbes use thisstepstep

this is why methane and alcohol production must bethis is why methane and alcohol production must beanaerobicanaerobic

however, anaerobic microbes cannot further oxidize thehowever, anaerobic microbes cannot further oxidize the

VFAVFA

2 2 4

volatileCOHNS heterotrophic

fatty + CO + H O + CH + energy + residualsmicrobesorganic compounds acids


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CatabolismCatabolism

RespirationRespiration

second step for aerobic microbessecond step for aerobic microbes simple organic compounds can be oxidized tosimple organic compounds can be oxidized to

carbon dioxide and water carbon dioxide and water

requires the presence of dissolved oxygenrequires the presence of dissolved oxygen

2 2 2

volatileaerobicfatty + O energy + CO + H O + residuals

microbesacids


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Anabolism Anabolism

Building of Cell ProtoplasmBuilding of Cell Protoplasm

energy from fermentation and/or respiration isenergy from fermentation and/or respiration isused to assemble the characteristic chemicalused to assemble the characteristic chemicalcomponents of cells from simple precursorscomponents of cells from simple precursors

precursors provide carbon, hydrogen, nitrogen andprecursors provide carbon, hydrogen, nitrogen andother elements found in cellular structureother elements found in cellular structure

chemical energy in adenosine triphosphate (ATP)chemical energy in adenosine triphosphate (ATP)

60 87 12 23simple C H N O Pmicrobes energyprecursors new cells


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Endogenous RespirationEndogenous Respiration

Aerobic Degradation of Cellular Material Aerobic Degradation of Cellular Material

microbes are organic compoundsmicrobes are organic compoundsunder substrateunder substrate --limiting conditions, microbeslimiting conditions, microbeswill feed on each other at a higher rate thanwill feed on each other at a higher rate thannew microbes can be formednew microbes can be formed

60 87 12 232 2 2 4 3

C H N O P aerobic + O CO + H O + PO + NH + residualsmicrobescellular material


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Environmental EffectsEnvironmental Effects

Microbes need more than organic carbon,Microbes need more than organic carbon,

dissolved oxygen and water dissolved oxygen and water temperature must be lifetemperature must be life --sustainingsustainingneed steady supply of food to maintain stableneed steady supply of food to maintain stable

microbial populationmicrobial populationpH needs to be monitoredpH needs to be monitored

low alkalinity can cause large changes in pHlow alkalinity can cause large changes in pH

Be careful with biocidesBe careful with biocides acid drain cleaner acid drain cleaner antibioticsantibiotics


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TemperatureTemperatureOverall, as Temperature Rises, MicrobialOverall, as Temperature Rises, Microbial

Activity Increases (but not too hot) Activity Increases (but not too hot)Microbes can be grouped by temperatureMicrobes can be grouped by temperaturepreferencepreference

Psychrophilic microorganismsPsychrophilic microorganisms optimum temperature 12optimum temperature 12 to 18to 18 CC

Mesophilic microorganismsMesophilic microorganisms optimum temperature 25optimum temperature 25 to 40to 40 CC

Thermophilic microorganismsThermophilic microorganisms optimum temperature 55optimum temperature 55 to 65to 65 CC


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SummarySummary

Aerobic Treatment of Wastewater Aerobic Treatment of Wastewater

takes advantage of a natural processtakes advantage of a natural processprocess can be easily engineered into aprocess can be easily engineered into abiological reactor for highbiological reactor for high --rate wastewaterrate wastewatertreatmenttreatmentremoves the oxygen demand fromremoves the oxygen demand from

wastewater before being discharged back intowastewater before being discharged back intothe hydrologic cyclethe hydrologic cycle

Carbon is transformed into cell mass andCarbon is transformed into cell mass andinto carbon dioxideinto carbon dioxide


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Part 1 Aerobic Treatment of Wastewater