anaerobic wasterwater treatment

8/12/2019 Anaerobic Wasterwater Treatment

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The Wastewater Treatment


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INTRO: WWT Process Categories

Suspended Growth Process microorganisms

are maintained afloat in the reactor by an

appropriate mixing method, i.e. activatedsludge, ponds and lagoons, and digesters.

Attached Growth Process microorganisms

are fixed to some object, i.e. trickling filters,

rotating biological contactors.


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INTRO: Types of Treatment

Aerobic Treatment with oxygen

Anaerobic Treatment without

oxygen

Anoxic Treatment BNR

NOTE: selection depends on degreeof treatment and pollution load


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Anaerobic WWT Process

Breakdown of organic matter bymicrobiological population in an

oxygen-free environment

Literally means without air

Used for high organic load


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Anaerobic WWT Process

a multi-stage process occurringsimultaneously

Every stage is accomplished bydifferent group of bacteria eachproducing by-products


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Anaerobic Metabolic Steps


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Acidogenesis & Acetogenesis


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Acidogenesis

acid production process

fermenting bacteria

volatile acids (butyric, propionic),alcohol, carbon dioxide, and

hydrogen


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Acidogenesis & Acetogenesis


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Methanogenesis

production of methane

aceticlastic and H2-oxidizing

methanogens (domain Archaea)methane and carbon dioxide

N.B. within a certain range of pH (6.5-

7.6) and temperature (35-37)


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A Closer Look at the H2Productionvia Anaerobic Oxidation

Rxn2 FermentationH2 produced is small

Most H2 comes from

oxidation of volatileand long chain fattyacids, Rxns 3 & 4called anaerobicoxidation

Rxns inhibited byhigh H2 partialpressures


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Interspecies Hydrogen Transport


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where vikis the stoichiometric coefficient for component i in

reaction k withmkcomponents, a

iis the activity of component

i, R is the universal gas constant, and T is absolute temperature

A close syntrophic relationship exist among microbial species

The same relationship and phenomenon occurs with butyrate

and propionate conversion to acetic acid and H2


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where J is the flux of H2bet. the organisms

(mol.sec-1); Rtis the H2 turnover rate (sec-1),Mdis the H2 mass in solution (mol); Az is thedistancebetween species (cm); C, and C, arethe H2concentrations at the surface of theH2-producing and H2-consuming species,respectively (mol.cm-3); and A is the cross-sectional area across which diffusion occurs(cm2); D is the molecular diffusivity of H2inwater (cm2 sec-1).

Diffusion drives the H2 transportbetween producing and

consuming species


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Typical SRT in Anaerobic at 35oC


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Dis/Advantagesof Anaerobic Systems

Low production of sludge/biosolids

High treatment efficiency, up to

90% COD removalLow capital cost, reactor tank

No O2, low power reqt

Methane prodn, biofuel

Sensitive to temperature and pH


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THANK YOU


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The Case of Biofilm


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The Case of Biofilm


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The Case of Biofilm


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The Case of Biofilm

anaerobic wasterwater treatment

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