Wastewater Treatment

Jae K. (Jim) ParkDepartment of Civil and Environmental

Engineering

University of Wisconsin-Madison

1

2

Microorganisms – ClassificationsEnergy Solar radiation: Photo-synthetic autotrophs,

e.g., algaeOrganics: Heterotrophs, e.g., activated sludge

biomass, denitrifiers, etc.Inorganics: Chemoautotrophs, e.g., nitrifiersOxygen useObligate (strict): use only one condition for

growthFacultative: use either dissolved oxygen or

chemically derived oxygen (from nitrate, sulfate or carbonate) for respiration and use organic materials for energy and growth

Temperature Psychrophiles: < 20°C., opt. 13°CMesophiles: 20~45°C, opt. 35°CThermophiles: 45~60°C, opt. 55°C

Organic Matter Energy for Mircoorganisms

3

Carbonaceous Energy: Carbon as energy

sourceHeterotrophs

Nitrogenous Energy: Nitrogen as energy

sourceChemoautotrophs

4

Energy Measurement (1)

Theoretical Oxygen Demand (ThOD)Chemical Oxygen Demand (COD)Biochemical (Biological) Oxygen

Demand (BOD)Carbonaceous BOD (C)Nitrogenous BOD (N)

Total Organic Carbon (TOC)

5

Energy Measurement (2)Theoretical Oxygen Demand (ThOD)1. Carbonaceous demand: C CO2; N NH3

2. Nitrogenous demand: NH3 HNO2; HNO2 HNO3

3. ThOD = O2 req. in steps 1& 2

Ex. Glycine (10 mg/L) [CH2(NH2)COOH] (MW = 75 g/mol)

1. Carbonaceous demandCH2(NH2)COOH + 1.5O2 2CO2 + H2O + NH3

2. Nitrogenous demandNH3 + 1.5O2 HNO2 + H2O; HNO2 + 0.5O2 HNO3

3. ThOD = [1.5 + (1.5+0.5)] mol O2/mol glycine

= 3.5 × 32 g O2/mol = 112 g O2/mol = 112 75 g/mol = 1.49 g O2/g

glycineThus, ThOD = 1.49 x 10 mg/L = 14.9 mg/LCannot be used if chemical composition is not

known.

Energy Measurement (3)

6

H2SO4

322

272ban 2cCrOH

28ca

nCO 8cHOcCrOHC HeatCatalyst

silver sulfateDichromate

3b

6a

32n

c

Chemical Oxygen Demand (COD) O2 req. for oxidation of organics Oxidize carbonaceous matter with a strong

oxidant (e.g., hot dichromate sol. with sulfuric acid)

Reduction of O2

4e- + 4H+ + O2 2H2O1 mole of O2 (32 g) 4e- equivalents1 g COD 1 g O2 1/8 electron equiv.

NH3 not oxidized (carbonaceous energy only) Aromatic hydrocarbons (benzene and

toluene) and pyridines are not oxidized

Domestic WastewaterCOD Fractionation

Influent COD(Sti)

Particulateunbiodeg.COD (Supi)

Sol. readilybiodegradable

COD (Sbsi)

Solubleunbiodeg.COD (Susii)

Partic. slowlybiodegradable

COD (Sbpi)

BiodegradableCOD (Sbi)

UnbiodegradableCOD (Sui)

100%

~80%

~20% ~60% ~7% ~13%

~20%

7

Energy Measurement (4)

Oxygen consumption by microorganisms

8

Carbonaceousenergy

Time, days

DO

con

sum

ed

, m

g/L

Nitrogenousenergy

5

BOD5

BODu

Biochemical (Biological) Oxygen Demand (BOD) O2 required for microbial decomposition

Inadequate to assess the electron donor capacity; after 5 days, still some biodegradable matters exist.

~30

9

Biochemical (Biological) Oxygen Demand (BOD) Carbonaceous BOD: aerobic heterotrophs

Decompose organic molecules to minerals (CO2) and residues

Obtain their cell carbon from the organic material

Nitrogenous BOD: obligate aerobic chemoautotrophs

Characteristics of nitrifiers (chemoautotrophs)DO < 2 mg/L action slowDO < 0.5 mg/L action ceasesOptimum pH: 8.0; pH < 7.2: slows downMore sensitive than heterotrophs to

toxinsSlow growers (longer sludge age

required)

Energy Measurement (5)

10

Inert Organic MatterMeasured with CODNot biodegraded, thus not measured with

BOD5

Polymerized waste productInert material from lysed cellsRefractory organics: humic acid (M.W. -

5000~100,000); fulvic acid (2,000~10,000)Certain high M.W. carbohydrates alone or in

combination with humic material are resistant to microbial attack.

High M.W. carbohydrates are excreted at the end of the logarithmic growth phase and help forming flocs by bridging of bacterial cells.

11

Acclimated Culture

Selection of populations by controlling environmental factors to encourage only the desired species.

An increase in the biodegradation rate of a chemical after exposure of the microbial community to the chemical for some period of time.

Example of Acclimation

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0 5 10 15 20 25 30 35 40Days

0

5

10

15

20

25

Con

cent

ratio

n, m

g/L

Result of acclimation

CO2 production

Microbial biomass

Chemical concentration

Lag phaseAcclimation

Bio

mass co

nc., m

g/L

CO

2 pro

ductio

n, v

ol.

13

Example AcclimationHazardous Industrial Wastewater

Biological Treatment

RB

W

Day 1

RB

WN

BW

Day 2

RB

WN

BW

Day 3

RB W

NB

W

Day 4N

BW

Day 5

Feedratio

RBW: Readily biodegradable wastewater, e.g., glucose, methanol, domestic wastewater, etc.

NBW:Not readily biodegradable wastewater, e.g., industrial wastewater, hazardous wastewater, polychlorinated biphenyls (PCBs), pentachlorophenol, etc.

Influence of Acclimated Biomass

on COD of Treated Wastewaters

14

CO

D, m

g/L

UntreatedRaw

Treated withunacclimated

biomass

Treated withacclimated

biomass

BOD5 equivalents

Not readilyBiodegradabl

eCOD

Non-biodegradableCOD

BOD: Not affected by acclimationCOD: Significantly affected by acclimation

Total COD – BOD5

BOD, CODCr, CODMn, TOC

Organic matter

Biodegradable Unbiodegradable

TOC

CODCr

CODMn

BOD5

Cl-, H2S

Cl-, H2S

Nitrification

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Total Organic Carbon (TOC) Oxidize in a combustion chamber with O2

Easy to measureGlucose, C6H12O6 (M.W. = 180)C6H12O6 + 6 O2 6 CO2 + 6 H2O6 moles O2 6 4 = 24 e-

24/6 = 4 e- available per unit organic CEx. 100 mg/L of glucose: TOC and COD = ? TOC: (6 12)/180 100 = 40 mg/L C COD: (6 32)/180 100 = 107 mg/L OGlycerol, C3H8O3 (M.W. = 92)C3H8O3 + 7/2 O2 3 CO2 + 4 H2O7/2 moles O2 7/2 4 = 14 e-

14/3 = 4.67 e- available per unit organic CEx. 100 mg/L of glycerol: TOC and COD = ? TOC: (3 12)/92 100 = 39 mg/L C COD: (3.5 32)/92 100 = 122 mg/L O

• TOC values are very similar for both glucose and glycerol; however, COD values are quite different.

• Thus, waste specific; cannot apply the result to other WWTPs.

• Good as an operational tool with previous historical data.Similar

Different

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Energy Measurement (6)O2 + 4H+ + 4 e- = 2 H2O

Energy Measurement (7)

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BOD5/COD ratio: a good indicator for biodegradability of a specific wastewater

Domestic wastewater BOD5/COD 0.4 ~ 0.8 BOD5/TOC 1.0 ~ 1.6

BOD5/COD 0.6: can be decomposed completely, biological treatment feasible

BOD5/COD 0.2: cannot be decomposed easily, chemical or physical treatment desired

BOD5/COD 0: has toxic materials

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TOC Analyzer

On-Line TOC Analyzer: a reagentless analyzer designed for continuous monitoring of organics.

Measure the amount of total organic carbon present in a liquid sample;

Convert inorganic carbon in the sample to CO2 after adding acid and strip CO2 by a sparge carrier gas;

Oxidize organic carbon by either combustion, UV persulfate oxidation, ozone promoted, or UV fluorescence; and

Measure CO2 stripped using the conductivity or non-dispersive infrared (NDIR) detection system.

19

Use of BOD5, COD, and TOCBOD5Good for regulating organic loading to a

receiving water body for DO depletion by heterotrophs

Not good for design since some organics biodegrade slowly or after acclimation

CODNot good for regulation since it does not reflect

true organic loading impact to aqua systemsGood for design if the input and output within

a biological system is monitored; true energy count for carbonaceous energy only

TOCGood for operating a wastewater treatment

plant due to real time monitoring capabilityValues cannot be transferred to other

wastewater due to specificity of carbon in the wastewater in terms of electro donor capability

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Priority PollutantsDesignated by EPA in 1979 A list of 126 specific pollutants that includes

14 heavy metals and 112 specific organic chemicals

Heavy Metals (Total and Dissolved): heavy, dense, metallic elements that occur only at trace levels in water, but are very toxic and tend to accumulate

Pesticides: DDT, Aldrin, Chlordane, Endosulfan, Endrin, Heptachlor, and Diazinon

Polycyclic Aromatic Hydrocarbons (PAHs): naphthalene, anthracene, pyrene, and benzo(a)pyrene

Polychlorinated biphenyls (PCBs): organic chemicals that formerly had widespread use in electrical transformers and hydraulic equipment

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Fats, Oils, and Grease (FOG)

Sewage backups and overflows can lead to costly clean ups and repairs, as well as public health concerns.

Many utilities acknowledge fat, oil, and grease (FOG) as the main cause of sewer clogging.

EPA estimated that utilities spend on average $33,000 per mile of sewer per year on capital project and $8,000 per mile for O&M (2004).

The capital investment in wastewater infrastructure is over $13 billion annually (EPA, 2002).

Local government and utilities pay up to 90% of capital expenditures on wastewater infrastructure (AMSA and WEF, 1999).

Causes of Sanitary Sewer Overflow

Blockages (48%)

Wet weather I/I (26%)

EPA, 2004

Mechanical orpower

failures (11%)

Misc. (5%)Line breaks (10%)

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Causes of Sewer Clogging

FOG (47%)

Grit, rock, and other debris (27%)

Roots (22%)

Roots and FOG (4%)

EPA, 200423

Sewer Clogging

24

FOG

Wastewater

Consequences of Sewer CloggingSewer overflow

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Consequences of Sewer CloggingOdor

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H2S + 2O2 H2SO4Crown corrosion of concrete pipes

Bacteria

Consequences of Sewer CloggingOdor

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Trans Fatty Acids (TFA)Created in an industrial process that adds

hydrogen to liquid vegetable oils to make them more solid

Easy to use, inexpensive to produce, and last a long time

Give foods a desirable taste and textureUse trans fats to deep-fry foods because

oils with trans fats can be used many times in commercial fryers

Raise bad LDL (low density lipoproteins ) cholesterol levels and lower your good HDL (high density lipoproteins) cholesterol levels

28

Use of Zero Trans Fatty Acids

Inefficient removal in conventional grease removal systems

Potential foaming in wastewater treatment plant aeration basins

No knowledge on the fate of zero trans fatty acids in sewers and wastewater treatment plants

29

Prevention of Sewer Clogging (1)

Grease trap or interceptors, exhaust hood filters, and floor mats

Proprietary grease removal devices

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Prevention of Sewer Clogging (2)

Chemicals and additives (emulsifiers, detergents or caustic substances) that claim to dissolve grease Prohibited for use as an additive because these

substances reduce the efficiency of the interceptor or trap

Best Management Practices (BMP) during daily operations to keep FOG out of drains leading to the sewer

EnzymesProhibited as additives due to the same effect as

emulsifiersMicroorganisms

Not prohibited as an additiveEducation

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32

NitrogenMain species

Organic nitrogenNH4

+: Ionized ammonia, nutrient to algae

NH3: Free (unionized) ammonia, toxic to fish

NO2-: Intermediate byproduct of

nitirification, < 1 mg/L, causes the hemoglobin in the blood to change to methemoglobin, cause methemoglobinemia (‘blue baby’ syndrome)

NO3-: Final product of nitrification,

undeveloped digestive tracts of an infant possess bacteria that convert nitrate into nitrite, < 10 mg/L

Nitrogen Transformationin Biological Treatment

ProcessesOrganic nitrogen(proteins, urea,

etc.)

Ammonia nitrogen(NH3-N)

Nitrite (NO2-)

Bacterial decompositionand hydrolysis

Organic nitrogen(bacterial cells)

Organic nitrogen(net growth)

Assimilation

Nitrate (NO3-)

O2

O2

Lysis and autooxidation

Nitrogen gas (N2)Denitrification

Organic carbon(substrate)

Nit

rifica

t ion

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Subdivision of Total Influent TKN

Influent TKN(Nti)

Unbiodegrad.soluble N

(Nui)

Biodegrad.N

(Nai)

Organicallybound N (Nti - Nai)

Unbiodegrad.Particulate N

(Npi)~3% ~10% ~12%

~75% ~25%

100%

NH3&NH4-

(Nai)

34

Total Kjeldahl Nitrogen (TKN): sum of organic nitrogen, ammonia(NH3), and ammonium (NH4

+) in biological wastewater treatment

Free Ammonia (Unionized, NH3) and Ionized (NH4

+) Ammonia

Temperature effectMoretoxic

Moretoxic

pH effect

Ammonia not regulated in winter

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36

Nitrification: Chemoautotrophs (1)

Oxygen demand

N gO g

3.43N

molg

14mol 1

O 2molg

16mol 1.5

NO to NHof Conversion 24

N gO g

1.14N

molg

14mol 1

O 2molg

16mol 0.5

NO to NOof Conversion 3-2

Nitrification: Conversion from ammonia to NO2

- / NO3-

Total oxygen demand for nitrification: 4.57 g O/g N

NH4+ + 1.5O2 NO2

- + H2O + 2H+ + New biomass

Nitrosomonas

NO2- + 0.5O2 NO3

- + New biomassNitrobactor

37

Nitrification: Chemoautotrophs (2)

CO2 (carbonate): carbon source

Ammonia: energy transfer source in a non-assimilative way so only a small amount of biomass (sludge) is produced

H+ +CO32-

→ HCO3-; H+ +HCO3

- → H2CO3

Alkalinity2H+ 1 mol alkalinity [CaCO3

(40+12+16×3=100 g/mol)]100 g Alk/14 g N = 7.14 g Alk consumed/g

N nitrified

NH4+ + 1.5O2 NO2

- + H2O + 2H+ + New biomass

Nitrosomonas

38

Nitrification: Chemoautotrophs (3)

Example Influent TKN = 42 mg N/L; Effluent TKN 2

mg/LAlkalinity = 200 mg/L as CaCO3

Oxygen demand?4.57 g O/g N × (42 – 2) mg N/L = 182.8 mg

O/L Alkalinity after nitrification?7.14 g Alk/g N × (42 – 2) mg N/L = 285.6

mg/L as CaCO3 Unless additional alkalinity (CaO, Na2CO3,

NaOH, etc.) is added, nitrification will stop (see the next slide).

Since the influent is 200 mg/L, 85.6 mg/L + 10~15 mg/L (residual) = 95.6~100.6 mg/L as CaCO3 required

Effect of pH on Nitrification

Operational range

Nitrifiers: very sensitive to pHThus, buffer capacity (alkalinity) of wastewater important

39

40

Denitrification: Heterotrophs (1)

2NO3- + 10e- + 12H+ → N2

+ 6H2O

N/e g 2.8e 10

molN g

14 mol 2

O2 + 4e- + 4H+ → 2H2O

O/e g 8

e 4mol

O g16 mol 1 2

N gO g

2.86

eN g

2.8

eO g

8

saved O 63%100tion)(nitrifica

N gO g

4.57

cation)(denitrifiN gO g

2.86

41

Denitrification : Heterotrophs (2)

~1 mol of H+ is recovered from denitrification

Thus, Alk of 3.57 g/g N recovered

For low alkalinity water, denitrification is recommended.

Denitrification conditionsNo O2Readily biodegradable soluble substrate (COD)

For complete removal of nitrogen species from wastewater: nitrification followed by denitrification

Substrate Requirementfor Denitrification

CODutilized = CODbiomass + O2 utilized = fcv X + O2 utilized = YCOD CODutilized + O2 utilized

fcv = COD/VSS = CODbiomass/X (mg COD/mg VSS)YCOD = CODbiomass/CODutilized (mg COD/mg COD)

O2 utilized = (1 - YCOD) CODutilized YCOD = fcv Yh (mg VSS/mg COD)

C5H7O2N + 5O2 5CO2 + 2H2O + NH3

(5 × 16 × 2 g) (1 × 113 g) = 1.42 mg COD/mg VSSCOD/VSS = 1.42 mg COD/mg VSS

O2 = (1 - fcvYh) CODutilized

Nitrate consumption per mg COD utilized2.86 mg O2/mg NO3

- N (1 - 1.42·0.47) mg O2/mg COD = 8.6 mg COD req./mg NO3

--N denitrified42

Biomassempirical formula

0.67

0.67 0.33

43

COD Requirement for Denitrification

ExampleCODinf = 400 mg/L, CODeff = 50 mg/L, TKNinf =

55 mg N/L, TKNeff = 5 mg N/L, Q = 10 MGDCOD (methanol) required for denitrification?Solution(55-5) mg N/L × 8.6 mg COD/mg N = 430 mg

COD/L req.[430-(400-50)] mg/L = 80 mg COD/L req.Methanol (CH3OH) (MW = 32 g/mol)CH3OH + 1.5O2 → CO2 + 2H2O80 mg COD/L×10 MGD 1.5×16×2 g COD/32

g MeOH = 202 kg/day = 445 lb of MeOH/day

Subdivision of Total Influent PInfluent TP

(Pti)

Organicallybound P (Pti - Pbi)

70 ~ 90% 10 ~ 30%

100%

10 ~ 20%in the activatedsludge process

Sol. PO4- (Psi)

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Source: human body waste, food waste, various household detergents

Phosphorus

Forms of Phosphate

45

Old Now Forms5 4 Orthophosphate3 0 Tripolyphosphate (detergents)1 0 Pyrophosphate (breakdown of tri-

P)1 1 Organic phosphates0 ? Hexametaphosphate (corrosion

inhibitor)10 5 Total

mg/L

Why? Ban of phosphate-based detergents

Phosphorus in Wastewater

Addition to waterCorrosion (and scale) control in drinking water

Industrial water softeningBoiler watersCleaning compounds

Sewage1.2 lb/capita/yr from human and food waste

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PAOs

Mechanisms of Polyphosphate-Accumulating Organisms (PAOs)

Anaerobic condition Aerobic condition

Poly-P

PO4 3- PAOs

New Cell

PHA

GlycogenPHA

Glycogen

NADH, ATP

Short chain fatty acids

(SCFAs)(Acetate)

Organic substrate

Facultative microbes

ATP

Poly-P

PO4 3-

ATP

47PHA: Polyhydroxyalkanoates

Observations in Biological Phosphorus Removal (BPR)

Systems

Ortho-P

PHA

Acetate

Glycogen

AN O

Poly-P

BulkLiquid

Biomass

Reaction Time 48PHA: Polyhydroxyalkanoates

BPR Mechanism

Anaerobic Aerobicm

g/L

Time

Poly-β-hydroxybutyrate (PHB)(Storage) PHB Poly-

PPoly-P 49

Biomass Biomass

Acetate

Ortho-P

Anaerobic/Oxic Process

Excess sludgeBetter SRT control

Readily biodegradablesoluble COD

Vital for P Uptake

SRT: Solid retention time, sludge age, or mean cell residence time (MCRT); total biomass in the system/biomass wasted/loss

50

51

Whole Effluent Toxicity

Bioassay

52

Bioassay

52

Mysidopsis bahia, female, approx. 6 mm in length

Ceriodaphnia dubia

Part of whole effluent toxicity (WET) tests for NPDES permit

Use of a biological organism to test for chemical toxicity

53

Use of Toxicity Testing in Water Quality Based

Toxics ControlTo characterize and measure the aggregate toxicity of an effluent or ambient waters

To measure compliance with whole effluent toxicity limits

As an investigative tool and to measure progress in a toxicity reduction program

As an ambient instream measure of toxicity to identify pollution sources

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54

BioassayTested sample: most commonly, effluent from

industrial or municipal wastewater dischargesSample holding time: max. 36 hrs stored at

4°CTest organisms

Ceriodaphnia dubia (water flea) Pimephales promelas (fathead minnow) Cyprinella leedsi (bannerfin shiner) Mysidopsis bahia (mysid shrimp) Menidia beryllina (tidewater silverside)

Acute test: 24, 48, or 96 hrs (species specific)Chronic test (short-term): 4~10 (7) days

Rules for Conducting Toxicity Tests

40 CFR 136.3 - Table 1A (List of Approved Biological Methods)

Effective November 15, 1995

Amended November 19, 2002 and effective December 19, 2002

Methods must be followed as they are written

Incorporate by Reference

Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms. 5th Edition, USEPA, Office of Water, October 2002, EPA 821-R-02-012

Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. 4th Edition, USEPA, Office of Water, October 2002, October 2002, EPA 821-R-02-013

Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine Organisms. 3rd Edition. USEPA, Office of Water, October 2002, EPA 821-R-02-014 56

USEPA Methods Documents

Health and safetyQuality assuranceFacilities, equipment and suppliesTest organisms and culture methodsDilution waterEffluent sampling and handlingEndpoints and data analysisIndividual test methodsReport preparation and test review

57

Test Types

Acute and Short-term Chronic TestsStatic non-renewalStatic renewalFlow through

Test Species dependentUse dependent

58

Test Design5 Concentrations + Control

Serial dilution’s of effluent and “control water” (also termed “dilution water”)

Dilution series of 0.5 or greaterSingle concentration test

Replicates

Randomization (organisms/chambers)

Acute Toxicity TestsTest Procedures

96 hours or less (species specific)Mortality is the measured endpointFor daphnia mortality determined by immobilization

AdvantagesLess expensive and time consuming than chronic

Endpoint is easy to quantifyDisadvantages

Indicates only lethal concentrationsOnly the effects of fast acting chemicals are exhibited 60

Acute Test Acceptability Criteria

Minimum control survival at least 90%

Temperature maintained at 20±1o C

Maximum test organism age at start:14 days for fish5 days for Mysid shrimp24 hours for daphnids (Ceriodaphnia dubia and Daphnia magna)

61

Short-term Chronic Toxicity Tests

Test ProceduresTypically 4-10 daysMortality, growth, fecundity, reproduction

AdvantagesMore sensitive than acute, assess

parameters other than lethalityMay better reflect real world

LimitationsMore costly and time intensive than acuteMore sensitive to low level contamination

62

Chronic Test Acceptability Criteria

Minimum control survival 80%Minimum control dry weight (average):

0.25 mg for fish0.20 mg for Mysid shrimp

Minimum of 15 young (average) for control C. dubia

Temperature maintained @ 25 +/- 1o CMaximum test organism age at start:

48 hours for fish7 days for Mysid shrimp24 hours for daphnids

63

Selection of Dilution Water

May be either a standard laboratory water or the receiving water

Choice of water is dependent on the objectives of the testAbsolute toxicity use standard waterEstimate of toxicity in uncontaminated receiving water, use receiving water

Contaminated receiving water, use laboratory water

64

Acute Test Endpoints

LC50 - Concentration of effluent that is lethal to 50 percent of the exposed organisms at a specific time of observation (e.g. 96 hr LC50), (expressed as % effluent)

NOAEC - No Observed Adverse Effect ConcentrationLowest concentration at which survival is not significantly different from the control

always set equal to 100% effluentEC - Effect Concentration

65

Test Data

Typical dose response where mortality increases as the concentration of effluent in the mixture increases.

LC50 would be somewhere between 25% effluent and 50% effluent.

0% mortality

6.25 %

Effluent0%

Mortality

Control

20 % Mortality

12.5 %

Effluent 40%

Mortality

25.0% Efflue

nt80%

Mortality

50.0% Efflue

nt100%

Mortality

100.0%

Effluent

66

Chronic Test Endpoints

IC25 - Inhibition Concentration - Concentration of effluent which has an inhibitory effect on 25% of the test organisms for the monitored effect, as compared to the control (expressed as % effluent).

NOEC - No Observable Effect Concentration - Highest concentration of effluent tested which shows no statistically significant effect on the organisms as compared to the control (expressed as % effluent).

67

Toxicity Values

NPDES permits in the past used a “no observable effect concentration” (NOEC) to measure chronic toxicity and a 96-hour lethal concentration 50 (LC50) to measure acute toxicity.

Permits are now being issued with an inhibition concentration 25% (IC25).

68

Limit: more stringent

LC50, IC25

LC50, IC25, NOAEC

Toxicity

Toxic Units (TU’s)

Reciprocal of the fractional LC50, NOEC, IC25 value

Calculated by dividing the value into 100TUa = 100/LC50TUc = 100/IC25

69

70

Methodology for Setting Limits (1)

IC25 is a calculation based on the design flow of the POTW and the seven-day low flow over 10 years in the receiving stream (7Q10) as follows:IC25 = design flow/(7Q10 + design flow) × 100

Example:The low flow for the receiving stream (7Q10) is

23 MGD. The design flow for the POTW is 4 MGD.IC25 = 4/(23+4) × 100

IC25 = 14.8% The POTW demonstrates toxicity if the test value

is less than or equal to the calculated value of 14.8%. This constitutes a violation of the NPDES permit.

71

A serial dilution that the laboratory: 59.2, 29.6, 14.8, 7.4, 3.7 and a control with 0% effluent.

Toxicity is demonstrated if there is a statistical significant difference in any dilution from the control set.

The difference can be in any of the three parameters: survival, reproduction, or growth.

In the example, the effluent fails if toxicity appears in the 14.8% or 7.4% or 3.7% dilutions.

Methodology for Setting Limits (2)

Redox Reaction

Organic molecule (C+H+O+N+S+P)

(wastewater, hazardous chemicals, etc.)

CO2, H+, and e-

A molecule

Oxidized

Reduced

Electron donor

Electron accepto

r72

Aerobic Condition

Aerobic respiration O2 present

Electron acceptor: O2 (→ H2O) Good for large volumes of dilute

wastewater (< 500 mg BOD5/L) High growth rates, thus high

sludge production (0.3~1 lb VSS/lb BOD5)

Produce a more stable end product

O

73

Anoxic Condition

Anaerobic respiration (denitrification)

No dissolved oxygen

NO3- and NO2

- present

Electron acceptor: NO2- and NO3

- (→ N2 + H2O)

Relatively high sludge production

Should be avoided in the clarifier

AX

74

Fermentation No O2, NO3

-, NO2-, or SO4

2- present Electron acceptor: endogenously generated

by the microorganism Good for concentrated wastes (> 1000 mg

BOD5/L) Low sludge production

Complex organic compounds

Low molecular weight fatty acids

CH4, CO2, and H2O

Anaerobic ConditionAN

75

Microbial Classification

76

ChemoautotrophH2 bacteriaSulfur bacteriaNitrifiersIron bacteria

ChemoheterotrophAnimalsMost bacteriaFungiProtozoa

H2, S, H2S, Fe2+, NH3, NO3-Organics (reduced)

Organics (reduced)H2O, S, H2S

PhotoautotrophGreen plantsAlgaePurple bacteriaGreen bacteria

PhotoheterotrophFew algaeCyanobactorSome purple & green bacteria

Chemical

Electron donor

Electron donor

Light

EnergyCarbon

CO2 Organics

77

Oxidation-Reduction Potential (ORP)

+300

+200

+100

0

-100

-200

-300

-400

ORPmV

Process

12

3

4

56 7

8

O2

SO42-

Carbonaceous organics

Electron acceptors

Conditions

Oxicor

aerobic

Anoxic

Fermentative anaerobic

1. Organic carbon oxidation2. Polyphosphate release3. Nitrification

4. Denitrification5. Polyphosphate uptake6. Sulfide formation

7. Acid formation8. Methane formation

NO3-

78

Three Origins of Life

Origin of life

Bacteria

Archaea

Eukarya

Phylogenetic Tree

The phylogenetic tree shows that the Eukarya are more closely related to the Archaea than they are to the Bacteria.

PROCARYOTA

79

ArchaeaA group of single-celled microorganismsRequires neither sunlight for photosynthesis

as do plants, nor oxygen. Absorbs CO2, N2, or H2S and gives off

methane gas as a waste product.

80

BacteriaSingle-celled microorganisms which can exist

either as independent (free-living) organisms or as parasites, typically 0.5–5.0 µm length

Shape

Ability to form spores Method of energy

production (glycolysis for anaerobes, cellular respiration for aerobes)

Nutritional requirements Reaction to the Gram stain

Classification

E. Coli