Bioremediation

Сентябрь 10, 2022

Содержание

2. What is Bioremediation?? Using subsurface microorganisms to transform hazardous contaminants into relatively harmless byproducts, such as
3. Bioremediation Background Natural Attenuation is Not fast enough, Not complete enough, Not frequently occurring enough to
4. Historical Perspective ~1900 Advent of biological processes to treat organics derived from human or animal wastes
5. Soil and Subsurface Contaminants Benzene and related fuel components (BTEX) Pyrene and other polynuclear aromatics Chlorinated
6. Sources of Contamination Industrial spills and leaks Surface impoundments Storage tanks and pipes Landfills Burial areas
7. Current Water Issues Associated with Gasoline Use Widespread contamination Major treat to drinking water resources Components
8. Typical Fuel (BTEX) Spill
9. Chlorinated Background Groundwater plumes of chlorinated solvents are widespread due to their extensive use at industrial,
10. Routes of DNAPL Migration
11. DNAPL Our Most Difficult Challenge DNAPL source Residual phase Trapped on lenses Pools in low areas
12. Treatment Techniques Soil Extraction Pump and Treat Physical and/or reactive barriers Air and Hydrogen Sparging Biological
13. Why use Bioremediation? No additional disposal costs Low maintenance Does not create an eyesore Capable of
14. Source Zone Treatment vs. Plume Treatment
15. Fundamentals of Biodegradation All organics are biodegradable, BUT biodegradation requires specific conditions There is no Superbug
16. Biotic Transformations Result of metabolic activity of microbes Aerobic and anaerobic biodegradation Reduces aqueous concentrations of
17. Bioremediation Processes Conversion of contaminants to mineralized (e.g. CO2, H2O, and salts) end-products via biological mechanisms
18. How Microbes Use the Contaminant Contaminants may serve as: Primary substrate enough available to be the
19. Requirements for Microbial Growth
20. Electron Exchange
21. Aerobic v. Anaerobic If oxygen is the terminal electron acceptor, the process is called aerobic biodegradation
22. Aerobic Oxidation Cometabolism Anaerobic Denitrification Manganese reduction Iron reduction Sulfate reduction Methanogenesis Bacterial Metabolism
23. Electron Acceptor Zones After O2 is depleted, begin using NO3– Continue down the list in this
24. Electron Acceptor Condition
25. Bioremediation Practice Understand physical and chemical characteristics of the contaminants of interest Understand the possible catabolic
26. Oxygen is of Primary Importance Most of the time oxygen is the primary factor limiting in
27. Two ways to introduce oxygen in situ Dissolved in water : Actively pumped: H2 O2 ,
28. Dehalogenation Stripping halogens (generally Chlorine) from an organic molecule Generally an anaerobic process, and is often
29. Dehalorespiration Certain chlorinated organics can serve as a terminal electron acceptor, rather than as a donor
30. Reductive Dechlorination An electron donor, such as hydrogen, and an electron acceptor is needed to transfer
31. Added Danger Dechlorination of PCE and TCE should be encouraged, but monitored closely The dechlorination products
32. Cometabolism Fortuitous transformation of a compound by a microbe relying on some other primary substrate Generally
33. Selective Enhancement of Reductive Dechlorination Competition for available H2 in subsurface Dechlorinators can utilize H2 at
34. Electron Donors Alcohols and acids Almost any common fermentable compound Hydrogen apparently universal electron donor, but
35. Electron Donors Acetate Hydrogen - Pickle liquor Acetic acid biochemical Polylactate esters Benzoate electrochemical Propionate Butyrate
36. Enhanced Bioattenuation Petroleum Chlorinated Technology Hydrocarbons Solvents (e– acceptor) (e– donor) Liquid Delivery Oxygen Benzoate Nitrate
37. Formation of a Usable Form of Electron Donor COD=Lactate + Acetate + Propionate
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Слайд 2

What is Bioremediation??
Using subsurface microorganisms to transform hazardous contaminants into relatively

harmless byproducts, such as ethene and water
Biodegrade
Mineralize
Biotransform
Techniques or types of bioremediation:
A component of Natural Attenuation
Enhanced Bioremediation
Bioaugmentation

Слайд 3

Bioremediation Background
Natural Attenuation is Not fast enough, Not complete enough, Not

frequently occurring enough to be broadly used for some compounds, especially chlorinated solvents
The current trend is to stimulate/enhance a site’s indigenous subsurface microorganisms by the addition of nutrients and electron donor
In some cases, bioaugmentation is necessary when metabolic capabilities are not naturally present.

Слайд 4

Historical Perspective
~1900 Advent of biological processes to treat organics derived from

human or animal wastes (and the sludges produced)
~1950 Approaches to extend wastewater treatment to industrial wastes
~1960 Investigations into the bioremediation of synthetic chemicals in wastewaters
~1970 Application in hydrocarbon contamination such as oil spills and petroleum in groundwater
~1980 Investigations of bioremediation applications for substituted organics
~1990 Natural Attenuation of ’70 and ’90, and the development of barrier approaches
~2000 High-rate in situ bioremediation; source zone reduction; bioaugmentation

Слайд 5

Soil and Subsurface Contaminants
Benzene and related fuel components (BTEX)
Pyrene and other

polynuclear aromatics
Chlorinated aromatics and solvents
Herbicides and pesticides
Nitroaromatic explosives and plasticizers

Слайд 6

Sources of Contamination
Industrial spills and leaks
Surface impoundments
Storage tanks and pipes
Landfills
Burial areas

and dumps
Injection wells

Слайд 7

Current Water Issues Associated with Gasoline Use
Widespread contamination
Major treat to drinking

water resources
Components of fuels are known carcinogens
Current fuel oxygenate, MTBE, very mobile and not very degradable
Ethanol is due to replace MTBE, but its behavior in the subsurface is not yet understood

Слайд 8

Typical Fuel (BTEX) Spill

Слайд 9

Chlorinated Background
Groundwater plumes of chlorinated solvents are widespread due to their

extensive use at industrial, DOD, and dry cleaner sites.
Chlorinated compounds commonly exist as dense nonaqueous-phase liquids (DNAPLs) that act as long-term, continuing sources that slowly solubilize into groundwater.
Known carcinogenic and toxic effects
Not a primary substrate for any known bacteria

Слайд 10

Routes of DNAPL Migration

Слайд 11

DNAPL Our Most Difficult Challenge
DNAPL source
Residual phase
Trapped on lenses
Pools in low

areas
Creates soluble plumes for years
Extremely hard to remediate

Слайд 12

Treatment Techniques
Soil Extraction
Pump and Treat
Physical and/or reactive barriers
Air and Hydrogen

Sparging
Biological (microbes)
Chemical (surfactants)

Слайд 13

Why use Bioremediation?
No additional disposal costs
Low maintenance
Does not create an eyesore
Capable

of impacting source zones and thus, decreasing site clean-up time

Слайд 14

Source Zone Treatment vs. Plume Treatment

Слайд 15

Fundamentals of Biodegradation
All organics are biodegradable, BUT biodegradation requires specific conditions
There

is no Superbug
Contaminants must be bioavailable
Biodegradation rate and extent is controlled by a “limiting factor”

Слайд 16

Biotic Transformations
Result of metabolic activity of microbes
Aerobic and anaerobic biodegradation
Reduces aqueous

concentrations of contaminant
Reduction of contaminant mass
Most significant process resulting in reduction of contaminant mass in a system

Слайд 17

Bioremediation Processes
Conversion of contaminants to mineralized (e.g. CO2, H2O, and salts)

end-products via biological mechanisms
Biotransformation refers to a biological process where the end-products are not minerals (e.g., transforming TCE to DCE)
Biodegradation involves the process of extracting energy from organic chemicals via oxidation of the organic chemicals

Слайд 18

How Microbes Use the Contaminant
Contaminants may serve as:
Primary substrate
enough available

to be the sole energy source
Secondary substrate
provides energy, not available in high enough concentration
Cometabolic substrate
fortuitous transformation of a compound by a microbe relying on some other primary substrate

Слайд 19

Requirements for Microbial Growth

Слайд 20

Electron Exchange

Слайд 21

Aerobic v. Anaerobic
If oxygen is the terminal electron acceptor, the process

is called aerobic biodegradation
All other biological degradation processes are classified as anaerobic biodegradation
In most cases, bacteria can only use one terminal electron acceptor
Facultative aerobes use oxygen, but can switch to nitrate in the absence of oxygen

Слайд 22

Aerobic
Oxidation
Cometabolism
Anaerobic
Denitrification
Manganese reduction
Iron reduction
Sulfate reduction
Methanogenesis
Bacterial Metabolism

Слайд 23

Electron Acceptor Zones
After O2 is depleted, begin using NO3–
Continue down the

list in this order
O2 ––> NO3– ––> Fe3+ ––> SO42– ––> CO2

Слайд 24

Electron Acceptor Condition

Слайд 25

Bioremediation Practice
Understand physical and chemical characteristics of the contaminants of interest
Understand

the possible catabolic pathways of metabolism and the organisms that possess that capability
Understand the environmental conditions required to:
Promote growth of desirable organisms
Provide for the expression of needed organisms
Engineer the environmental conditions needed to establish favorable conditions and contact organisms and contaminants

Слайд 26

Oxygen is of Primary Importance
Most of the time oxygen is

the primary factor limiting in situ biodegradation
In most cases if adequate oxygen can be supplied then biodegradation rates are adequate for remediation
Other limiting factors exist, but are usually secondary to oxygen

Degradation for Benzene: C6H6 + 7.5O2 ––> 6CO2 + 3H2O

Слайд 27

Two ways to introduce oxygen in situ
Dissolved in water :

Actively pumped: H2 O2 , aerated water
Passively: ORC ® , membrane, aeration
In gaseous form, usually air
Bioventing above the water table
Air sparging below the water table

Oxygen Supply is the Key to Aerobic
In Situ Bioremediation

Слайд 28

Dehalogenation
Stripping halogens (generally Chlorine) from an organic molecule
Generally an anaerobic process,

and is often referred to as reductive dechlorination
R–Cl + 2e– + H+ ––> R–H + Cl–
Can occur via
Dehalorespiration (anaerobic)
Cometabolism (aerobic)

Слайд 29

Dehalorespiration
Certain chlorinated organics can serve as a terminal electron acceptor,

rather than as a donor
Confirmed only for chlorinated ethenes
Rapid, compared to cometabolism
High percentage of electron donor goes toward dechlorination
Dehalorespiring bacteria depend on hydrogen-producing bacteria to produce H2, which is the preferred primary substrate

Слайд 30

Reductive Dechlorination
An electron donor, such as hydrogen, and an electron acceptor

is needed to transfer from one product to the next

Слайд 31

Added Danger
Dechlorination of PCE and TCE should be encouraged, but monitored

closely
The dechlorination products of PCE are more hazardous than the parent compound
DCE is 50 times more hazardous than TCE
Vinyl Chloride is a known carcinogen

Слайд 32

Cometabolism
Fortuitous transformation of a compound by a microbe relying on some

other primary substrate
Generally a slow process - Chlorinated solvents don’t provide much energy to the microbe
Most oxidation is of primary substrate, with only a few percent of the electron donor consumption going toward dechlorination of the contaminant
Not all chlorinated solvents susceptible to cometabolism (e.g., PCE and carbon tetrachloride)

Слайд 33

Selective Enhancement of Reductive Dechlorination
Competition for available H2 in subsurface
Dechlorinators can

utilize H2 at lower concentrations than methanogens or sulfate-reducers
Addition of more complex substrates that can only be fermented at low H2 partial pressures may provide competitive advantage to dechlorinators

Слайд 34

Electron Donors
Alcohols and acids
Almost any common fermentable compound
Hydrogen apparently universal electron

donor, but no universal substrate
Laboratory or small-scale field studies required to determine if particular substrate will support dechlorination at particular site

Слайд 35

Electron Donors
Acetate Hydrogen - Pickle liquor
Acetic acid biochemical Polylactate esters
Benzoate electrochemical Propionate
Butyrate gas

sparge Propionic acid
Cheese whey Humic acids - Sucrose
Chicken manure naturally occurring Surfactants -
Corn steep liquor Isopropanol Terigitol5-S-12
Ethanol Lactate Witconol 2722
Glucose Lactic acid Tetraalkoxsilanes
Hydrocarbon Methanol Wastewater
contaminants Molasses Yeast extract
Mulch

Слайд 36

Enhanced Bioattenuation
Petroleum Chlorinated
Technology Hydrocarbons Solvents
(e– acceptor) (e– donor)
Liquid Delivery Oxygen Benzoate
Nitrate Lactate
Sulfate Molasses
Carbohydrates
Biosparge Air (oxygen) Ammonia
Hydrogen
Propane
Slow-release Oxygen Hydrogen

(ORC) (HRC)

Слайд 37

Formation of a Usable Form of Electron Donor
COD=Lactate + Acetate

+ Propionate

Bioremediation

Содержание

What is Bioremediation??Using subsurface microorganisms to transform hazardous contaminants into relatively

Bioremediation BackgroundNatural Attenuation is Not fast enough, Not complete enough, Not

Historical Perspective~1900 Advent of biological processes to treat organics derived from

Soil and Subsurface ContaminantsBenzene and related fuel components (BTEX)Pyrene and other

Sources of ContaminationIndustrial spills and leaksSurface impoundmentsStorage tanks and pipesLandfillsBurial areas

Current Water Issues Associated with Gasoline UseWidespread contaminationMajor treat to drinking

Typical Fuel (BTEX) Spill

Chlorinated BackgroundGroundwater plumes of chlorinated solvents are widespread due to their

Routes of DNAPL Migration

DNAPL Our Most Difficult ChallengeDNAPL sourceResidual phaseTrapped on lensesPools in low

Treatment TechniquesSoil Extraction Pump and TreatPhysical and/or reactive barriersAir and Hydrogen

Why use Bioremediation?No additional disposal costsLow maintenanceDoes not create an eyesoreCapable

Source Zone Treatment vs. Plume Treatment

Fundamentals of BiodegradationAll organics are biodegradable, BUT biodegradation requires specific conditionsThere

Biotic TransformationsResult of metabolic activity of microbesAerobic and anaerobic biodegradationReduces aqueous

Bioremediation ProcessesConversion of contaminants to mineralized (e.g. CO2, H2O, and salts)

How Microbes Use the ContaminantContaminants may serve as:Primary substrate enough available

Requirements for Microbial Growth

Electron Exchange

Aerobic v. AnaerobicIf oxygen is the terminal electron acceptor, the process

AerobicOxidation CometabolismAnaerobicDenitrificationManganese reductionIron reductionSulfate reductionMethanogenesisBacterial Metabolism

Electron Acceptor ZonesAfter O2 is depleted, begin using NO3–Continue down the

Electron Acceptor Condition

Bioremediation PracticeUnderstand physical and chemical characteristics of the contaminants of interestUnderstand

Oxygen is of Primary Importance Most of the time oxygen is

Two ways to introduce oxygen in situ Dissolved in water :

DehalogenationStripping halogens (generally Chlorine) from an organic moleculeGenerally an anaerobic process,

Dehalorespiration Certain chlorinated organics can serve as a terminal electron acceptor,

Reductive DechlorinationAn electron donor, such as hydrogen, and an electron acceptor

Added DangerDechlorination of PCE and TCE should be encouraged, but monitored

CometabolismFortuitous transformation of a compound by a microbe relying on some

Selective Enhancement of Reductive DechlorinationCompetition for available H2 in subsurfaceDechlorinators can

Electron DonorsAlcohols and acidsAlmost any common fermentable compoundHydrogen apparently universal electron

Electron DonorsAcetate Hydrogen - Pickle liquor Acetic acid biochemical Polylactate estersBenzoate electrochemical Propionate Butyrate gas

Enhanced Bioattenuation Petroleum ChlorinatedTechnology Hydrocarbons Solvents (e– acceptor) (e– donor)Liquid Delivery Oxygen Benzoate Nitrate Lactate Sulfate Molasses CarbohydratesBiosparge Air (oxygen) Ammonia Hydrogen PropaneSlow-release Oxygen Hydrogen

Formation of a Usable Form of Electron Donor COD=Lactate + Acetate

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