as microbiology – good actors and bad seth terry, ph.d

AS Microbiology – Good Actors and Bad

AS Microbiology – Good Actors and Bad

Seth Terry, Ph.D.

2 – AS Microbiology, Vail PWO Conference 2006

GoodGood


BadBad


UGLY!UGLY!


A key question for operatorsA key question for operators

Of course, settleability represents only one aspect of ‘goodness’

So, as an operator, you have to ask yourself the question:

“Do you stand for ‘goodness’, or - for ‘badness’?”

Judge Smails, Caddyshack (1980)


What makes a sludge “good”What makes a sludge “good”

Controllable settling

Appropriate microbiology


ControllabilityControllability

Indicated by an ABSENCE of filaments

??????

NO! A widespread misconception

Sludges without filaments generally settle too quickly, leaving behind turbid effluent

Sludges with too many filaments generally produce crystal clear supernatants, but settle at rates incompatible with secondary clarifiers

The ‘sweet spot’ lies somewhere in between


Appropriate MicrobiologyAppropriate Microbiology

Growing the right bugs To control settleability

Relative proliferation of filaments

To achieve permit compliance BOD oxidizers

Nitrifiers

Denitrifiers

Polyphosphate-accumulating organisms (PAOs)

Fermenting facultative organisms

To avoid odor Minimizing sulfate reducing bacteria (SRBs)


Population ControlPopulation Control

Clearly, we would like to control the bacterial population in our aeration tanks

We do so indirectly

Bacteria are very effective at exploiting environmental niches

Food source, DO level, temperature, water chemistry, metabolites from other bacteria

Environment controls population

Microbiology BasicsMicrobiology Basics


‘Bugs’ Are Not ‘True Bugs’‘Bugs’ Are Not ‘True Bugs’

Two pairs of wings

Partially hardened first pair

Jointed piercing and sucking mouthparts

Series of nymphal stages in development

Phylum Arthropoda, class Insecta, order Hemiptera


Bugs in Wastewater TreatmentBugs in Wastewater Treatment

Bacteria – Single-celled organisms

Prokaryotes

Lack discrete nuclear membrane

Protozoa – Single-celled animals

Eukaryotes

DNA housed in nuclear membrane

Metazoa – Multi-celled animals

Specialization of cellular functions


Bacterial TypesBacterial Types

OriginEnteric

Soil

FeedHeterotrophic (organic)

Autotrophic (inorganic)

Growth PatternFloc former

Filament

Final Electron Acceptor

Aerobic respiration

O2

Anaerobic respiration

NO3-

SO42-

CO32-

Anaerobic fermentation

Organic acids & alcohols

Methane


Phylogenetic ClassificationPhylogenetic Classification

Tending to replace out-dated system based on phenotypic relationships, particularly in microbiology

Latest system uses genetic differences detected by molecular techniques (molecular chronometer)

Root = primeval organism, the ‘Universal Ancestor’ Domains: Bacteria, Archaea, Eukarya, (Korarchaeota)

Kingdoms: at least 14, but probably >50!

(Class)

(Order)

(Family)

Genus: usually 93% to 95% molecular similarity

Species: isolated monoculture (single bacteria culture)

} Academic work!


Metabolic ClassificationMetabolic Classification

All Organisms

Chemotrophs:Light not required

Phototrophs:Light required

Chemolithotrophs:Electrons from

inorganic chemicals

Chemoorganotrophs:Electrons AND C

from organic chemicals(‘HETEROTROPHS’)

Chemolithoautotrophs:C from CO2

(‘AUTOTROPHS’)

Mixotrophs:C from organic source(‘HETEROTROPHS’)

Photoautotrophs:C from CO2

(ALGEA)

Photoheterotrophs:C from organic source

(purple non-sulfur bacteria)

First distinction is made on relation to light

Second distinction may be made on electron source

Third distinction is made on carbon source for cell growth

Adapted from Brock, 9th Ed.


Classification Based on e--acceptorClassification Based on e--acceptor

Distinction based upon relationship to oxygen

Class Sub-group Relationship to O2 Types of Metabolism

Obligate DO required Aerobic respiration

MicroaerophilicDO required, but only at relatively low concentrations

Aerobic respiration

FacultativeDO not required, but provides optimum growth rate

Aerobic/anaerobic respiration, fermentation

Obligate DO harmful or lethal Anaerobic respiration, fermentation

AerotolerantOrganisms are indifferent to presence of DO Fermentation

Aerobes

Anaerobes

Adapted from Brock, 10th Ed.


Floc-Forming Bacterial SpeciesFloc-Forming Bacterial Species

Pseudomonas

Flavobacterium

Achromobacter

Bacillus

Alcaligenes

Micrococcus


Electron Photo of a “Floccy” FlocElectron Photo of a “Floccy” Floc


Electron Photo of a Filamentous FlocElectron Photo of a Filamentous Floc

a.k.a “The Sponge”


Filamentous Bacterial SpeciesFilamentous Bacterial Species

Sphaerotilus natans

Beggiatoa

Haliscomenobacter hydrossis

Microthrix parvicella

Nocardia-forms

Nostocoida limicola

Thiothrix


Common Eikelboom “Type” FilamentsCommon Eikelboom “Type” Filaments

0041

0092

021N

0675

0914

0961

1701

1851


Filament Growth EnvironmentsFilament Growth Environments

Low DO

Septic/Sulfide

Organic loading rate and biodegradability

pH

Nutrient deficiency

Completely mixed, continuously fed


F/M vs. Protozoa/Metazoa PopulationsF/M vs. Protozoa/Metazoa Populations

0 .1 .2 .3 .4 .5 .6

F/M lb BOD/lb MLSS (Eikelboom, 2000)

MetazoaShelled Am.CarnivoresStalksCrawlersFree-Swim.FlagellatesAmoeba

Range

MostCommon

Elements of ControlElements of Control


Environmental FactorsEnvironmental Factors

Physical

Chemical

Biological

Controlled

Uncontrolled


Physical FactorsPhysical Factors

Temperature

Mixing

DO

Hydraulics

Detention time

Mixing


Chemical FactorsChemical Factors

BODForm of food

Availability of food

Basic water chemistry pH

Generally between 7.0 and 7.5

AlkalinityNitrification requirement

Nutrients

Toxins


Biological FactorsBiological Factors

Terminal electron acceptor

Aerobic

Anoxic

Anaerobic

Sludge age

Mean cell residence time (MCRT)


Energy Production/UtilizationEnergy Production/Utilization

OrganicMatter

Electrons

Bacteria


Final Electron AcceptorsFinal Electron Acceptors

O2 – aerobic

NO3- – anoxic

SO42- – anaerobic

CO32- – anaerobic

Organic compounds

Fermentation

Alcohols

Acids


Energy DistributionEnergy Distribution

Aerobic

33% Heat

67% maintenance & growth

Maintenance

50% high load

70% low load

Growth

50% high load

30% low load

Anaerobic

4.6% heat

95.4% maintenance & growth

Maintenance

88.5%

Growth

6.9%


Food to Microorganism RatioFood to Microorganism Ratio

F/M or F:M

lb BOD removed per lb MLVSS in system

Basis

System F/M – 24 hour period

Instantaneous F/M – Right now

Highest at head of tank, gets smaller down the tank

Related to MCRT


Log #Viable

Organisms

Time

Heterotrophic Growth Curve

Autotrophic Growth Curve

Log

StationaryDeath

Lag

Bacterial Growth CurveBacterial Growth Curve

Declining Growth

Accelerated Growth


Active Microorganism NumbersActive Microorganism Numbers

Time or Distance Down the Aeration Tank

# V

iabl

e M

icro

orga

nism

s

Log growthphase

Declininggrowth phase Endogenous phase


Changing F/MChanging F/M

Q

RAS

F/M

M

F


Growth Curve with FeedGrowth Curve with Feed

Aeration period

# A

ctiv

e M

icro

orga

nism

s Raw waste Raw waste

Length of Aeration TankReturn to Aeration Tank


Primary and Secondary GrowthPrimary and Secondary Growth

Time

Num

bers

of

mic

roor

gani

sms Secondary predominancePrimary predominance

Secondary organisms feedupon cell-lysis products,primarily protein


Soluble BOD vs. TimeSoluble BOD vs. Time

Aeration period

5-da

y B

.O.D

.B.O.D. determined on settled supernatant

Biosorption zone


Primary and Secondary OrganismsPrimary and Secondary Organisms

Primary

Carbohydrates

Metabolized by many different genera

Organic acids, aldehydes, ketones, alcohols

Pseudomonas

Micrococcus

Bacillus

Achromobacter


Primary and Secondary OrganismsPrimary and Secondary Organisms

Secondary

Proteins

Lysis of bacterial cells

Cell contents primarily protein

Alcaligenes

Flavobacterium


Measures of MetabolismMeasures of Metabolism

Direct growth methods

Micro-counting

Particle counting

Indirect methods

SOUR/Respiration Rate

ORP

Direct biochemical methods

NADH


SOUR vs. A-Tank LengthSOUR vs. A-Tank Length

Distance along aeration tank

Oxy

gen

util

izat

ion

QuestionsQuestions

as microbiology – good actors and bad seth terry, ph.d

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