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5 – AS Microbiology, Vail PWO Conference 2006
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)
6 – AS Microbiology, Vail PWO Conference 2006
What makes a sludge “good”What makes a sludge “good”
Controllable settling
Appropriate microbiology
7 – AS Microbiology, Vail PWO Conference 2006
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
8 – AS Microbiology, Vail PWO Conference 2006
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)
9 – AS Microbiology, Vail PWO Conference 2006
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
11 – AS Microbiology, Vail PWO Conference 2006
‘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
12 – AS Microbiology, Vail PWO Conference 2006
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
13 – AS Microbiology, Vail PWO Conference 2006
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
14 – AS Microbiology, Vail PWO Conference 2006
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!
15 – AS Microbiology, Vail PWO Conference 2006
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.
16 – AS Microbiology, Vail PWO Conference 2006
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.
17 – AS Microbiology, Vail PWO Conference 2006
Floc-Forming Bacterial SpeciesFloc-Forming Bacterial Species
Pseudomonas
Flavobacterium
Achromobacter
Bacillus
Alcaligenes
Micrococcus
18 – AS Microbiology, Vail PWO Conference 2006
Electron Photo of a “Floccy” FlocElectron Photo of a “Floccy” Floc
19 – AS Microbiology, Vail PWO Conference 2006
Electron Photo of a Filamentous FlocElectron Photo of a Filamentous Floc
a.k.a “The Sponge”
20 – AS Microbiology, Vail PWO Conference 2006
Filamentous Bacterial SpeciesFilamentous Bacterial Species
Sphaerotilus natans
Beggiatoa
Haliscomenobacter hydrossis
Microthrix parvicella
Nocardia-forms
Nostocoida limicola
Thiothrix
21 – AS Microbiology, Vail PWO Conference 2006
Common Eikelboom “Type” FilamentsCommon Eikelboom “Type” Filaments
0041
0092
021N
0675
0914
0961
1701
1851
22 – AS Microbiology, Vail PWO Conference 2006
Filament Growth EnvironmentsFilament Growth Environments
Low DO
Septic/Sulfide
Organic loading rate and biodegradability
pH
Nutrient deficiency
Completely mixed, continuously fed
23 – AS Microbiology, Vail PWO Conference 2006
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
25 – AS Microbiology, Vail PWO Conference 2006
Environmental FactorsEnvironmental Factors
Physical
Chemical
Biological
Controlled
Uncontrolled
26 – AS Microbiology, Vail PWO Conference 2006
Physical FactorsPhysical Factors
Temperature
Mixing
DO
Hydraulics
Detention time
Mixing
27 – AS Microbiology, Vail PWO Conference 2006
Chemical FactorsChemical Factors
BODForm of food
Availability of food
Basic water chemistry pH
Generally between 7.0 and 7.5
AlkalinityNitrification requirement
Nutrients
Toxins
28 – AS Microbiology, Vail PWO Conference 2006
Biological FactorsBiological Factors
Terminal electron acceptor
Aerobic
Anoxic
Anaerobic
Sludge age
Mean cell residence time (MCRT)
29 – AS Microbiology, Vail PWO Conference 2006
Energy Production/UtilizationEnergy Production/Utilization
OrganicMatter
Electrons
Bacteria
30 – AS Microbiology, Vail PWO Conference 2006
Final Electron AcceptorsFinal Electron Acceptors
O2 – aerobic
NO3- – anoxic
SO42- – anaerobic
CO32- – anaerobic
Organic compounds
Fermentation
Alcohols
Acids
31 – AS Microbiology, Vail PWO Conference 2006
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%
32 – AS Microbiology, Vail PWO Conference 2006
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
33 – AS Microbiology, Vail PWO Conference 2006
Log #Viable
Organisms
Time
Heterotrophic Growth Curve
Autotrophic Growth Curve
Log
StationaryDeath
Lag
Bacterial Growth CurveBacterial Growth Curve
Declining Growth
Accelerated Growth
34 – AS Microbiology, Vail PWO Conference 2006
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
36 – AS Microbiology, Vail PWO Conference 2006
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
37 – AS Microbiology, Vail PWO Conference 2006
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
38 – AS Microbiology, Vail PWO Conference 2006
Soluble BOD vs. TimeSoluble BOD vs. Time
Aeration period
5-da
y B
.O.D
.B.O.D. determined on settled supernatant
Biosorption zone
39 – AS Microbiology, Vail PWO Conference 2006
Primary and Secondary OrganismsPrimary and Secondary Organisms
Primary
Carbohydrates
Metabolized by many different genera
Organic acids, aldehydes, ketones, alcohols
Pseudomonas
Micrococcus
Bacillus
Achromobacter
40 – AS Microbiology, Vail PWO Conference 2006
Primary and Secondary OrganismsPrimary and Secondary Organisms
Secondary
Proteins
Lysis of bacterial cells
Cell contents primarily protein
Alcaligenes
Flavobacterium
41 – AS Microbiology, Vail PWO Conference 2006
Measures of MetabolismMeasures of Metabolism
Direct growth methods
Micro-counting
Particle counting
Indirect methods
SOUR/Respiration Rate
ORP
Direct biochemical methods
NADH
42 – AS Microbiology, Vail PWO Conference 2006
SOUR vs. A-Tank LengthSOUR vs. A-Tank Length
Distance along aeration tank
Oxy
gen
util
izat
ion