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NRSC 333 > 8. Bioremediation Treatments > Flashcards

8. Bioremediation Treatments Flashcards

1
Q

Les grandes lignes of bioremediation (4 steps)

A
  1. Put bacteria on the contaminated site
  2. The bacteria secrete enzymes that attack fats, oil, grease, sugar, starch, breaking them down
  3. Bacteria can then eat the leftover smaller bits
  4. Bacteria excrete CO2 and water
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2
Q

BTEX

A

benzene, toluene, ethylbenzene, xylene

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3
Q

ppm

A

parts per million = mg pollutant / kg or L of sample

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4
Q

ppb

A

parts per billion = μm pollutant / kg or L of sample

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5
Q

TPH

A

Total Petroleum Hydrocarbons

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6
Q

What is TPH for?

A

It is a common chemical procudure used to quantify the amount of hydrocarbons in a contaminated sample

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7
Q

4 common modes of biodegradation of organic compounds

A
  1. Cellular metabolism
  2. Detoxifying enzymatic reactions
  3. Non-enzymatic reactions
  4. Cometabolism
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8
Q

Two types of cellular metabolism

A
  1. Catabolism
  2. Anabolism
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9
Q

What are we doing with carbon in catabolism

A

C used as a source of energy and CO2 released

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10
Q

What are we doing with carbon in anabolism

A

C converted to biomass

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11
Q

In cellular metabolsim, what are the pollutants converted to? (3)

A
  • Cells (biomass)
  • Residual organics
  • Inorganics (CO2, etc.)
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12
Q

What are types of detoxifying enzymatic reactions? (2)

A
  • Antibiotic degradation
  • Metal transformations
  • i.e. transforming heavy metals into there less toxic forms
  • e.g. transforming methylmercury to Hg2+ to Hg 0 and transforming uranium 6+ to U4+)
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13
Q

Non-enzymatic reactions

A

When by-products of microbial metabolism change the environment

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14
Q

How do non-enzymatic reactions occur? (4)

A
  • Depletion of O2
  • Change in pH
  • Production of reactive compounds like H2O2 → strong oxidant
  • SO4 via SRB can be transformed to H2S which reacts with heavy metals (Zn, Cd, Pb) to create insoluble metal sulfides
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15
Q

Cometabolism

A
  • Compound modified but NOT used for generation of energy or biomass
  • Enzymes with low specifity
  • Often via excreted enzymes i.e. extracellular enzymes
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16
Q

Is an integrated multi-disciplinary approach needed for bioremediation?

A

yes

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17
Q

Some fields involved in the successful use of bioremediation (5)

A
  • Waste
  • Optimal microbiology
  • Remediation technology
  • Analystical methods
  • Statistical sampling
  • Regulatory approval
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18
Q

Parameters involved in successful use of bioremediation (14)

A
  • composition properties
  • nutrients
  • moisture
  • aeration
  • inoculum
  • land treatment
  • bioslurry
  • composting
  • bioventing
  • correct method
  • QA/QC (quality assurance/quality control)
  • statistic procedures
  • cleanup standards
  • closure requiremetns
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19
Q

Remediation technologies in order of most expensive to least expensive:
* above ground bioremediation
* thermal desoprtion
* landfill
* incineration
* soil washing

A
  • incineration
  • landfill
  • thermal incineration
  • soil washing
  • aboveground bioremedation
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20
Q

Conventional remediation technologies (5)

A
  • Soil excavation
  • Incineration
  • Containement: landfill, land farming, solidification/stabilization (tar ponds example)
  • Chemical additions
  • Soil washing
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21
Q

Sydney Tar Ponds example
What were the contaminants? (4)

A
  • hydrocarbons
  • PAHs
  • heavy metals
  • PCBs
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22
Q

Sydney Tar Ponds example

Remediation strategy

A

Solidification / Stabilization (S/S) with cement

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23
Q

Sydney Tar Ponds example

What is Solidification / Stabilization (S/S) with cement?

A
  • Contaminated sediments are mixed with cement powder
  • This solidifies the contaminated soil and prevent pollutants from moving
    * such as rain causing leaching of pollutants into the groundwater or being carried into streams by rain or snowmelt
  • So it’s just stabilizing the contaminants so they don’t go anywhere, not removing them
24
Q

Sydney Tar Ponds example

What happens after the completion of the S/S process

A
  • The solidified areas get covered with an engineered cap consiting of a high-density polyethylene liner or clay, folllowed by layers of gravel or soil.
  • Then, the surface was planted with grass and other vegetation
25
Q

Sydney Tar Ponds example

Weakenesses of S/S (2)

A
  • high cost
  • pollutant not necessarily destroyed, as they may be converted to another form which are still pollutants and/or moved to another environment
26
Q

Sydney Tar Ponds example

Bioremediation is usually better than conventional technologies because … ? (2 pros + 1 con)

A
  • The pollutants are usually totally destroyed
  • The cost is generally lower
  • But sometimes it is slower and with an unpredictable outcome
27
Q

Types of bioremediaiton (2)

A
  1. Bioremediation following excavation
  2. In situ bioremediation
28
Q

Types of In situ bioremediation (2)

A
  1. Intrinsic bioremediation
  2. Enhanced in situ bioremediation
29
Q

What is intrinsic bioremediation? + characteristics (4)

A
  • No intervention
  • Rely on existing microbes, nutrients and other environmental parameters
  • Inexpensive but destruction of pollutant could take a long time or never be completed
  • Requires a comprehensive monitoring program to ensure contamination is not travelling off-site, limited toxicity, and contamination concentrations are being reduced
30
Q

What is enhanced in situ bioremediation?

A
  • Enhanced by additions but no excavation
  • Can speed up degradation time and percent reduction in pollutant concentration
31
Q

What are the two ways to do enhanced in situ bioremediation?

A
  1. Bioaugmentation
  2. Biostimulation
32
Q

What is bioaugmentation?

A

Addition of microbes (natural or genetically engineered) known to break down the pollutant

33
Q

Bioaugmentation isn’t as commonly used because it doesn’t work as well. Why is that?

A
  • Problem is that these new microbes require other growth factors and so they will deplete other nutrients in the site
  • Another problem is that there is a reason that the already present microbes are not doing their job currently, there is probably something missing, such that stimulation should work better
34
Q

What is biostimulation

A

Addition of something to the contaminated site to stimulate the already present microbes in proceeding with bioremediation

35
Q

Biostimulation

What can you add to stimulate? (4)

A
  • Addition of O2 (air) or another electron acceptor
  • Addition of fertilizers to optimize the C:N:P ratio, ensuring that growth is not limited by a nutrient and thus the growth rate of biodegrading microbes is maximized
  • Addition of inducers (of gene expression) i.e. CH4 stimulates production of methane monooxygenase (MMO), known for ability to degrade some pollutants via cometabolism
  • Alteration of any other important environmental parameter
36
Q

How does one know what to add and in what proportions?

Need to preform a bioremediation assessment study to determine 4 elements… and then what do you do with those 4 elements

A
  1. Are the contaminants biodegradable
  2. Are biodegradive microbes present in the contaminated sites?
  3. Are the contaminated environement parameters (temp, pH) optimal for biodegradation to occur?
  4. Identify any paramaters that may be limiting biodegradive activity

Then, using the assessment, develop a bioremediation treatment strategy
* Optimize biostimulation parameters to maximise metabolize activity related to the biodegradation of the pollutant
* Apply optimized parameters to the field for in situ bioremediaiton strategy

37
Q

Bioremediation assessment: Procedures for understanding the biodegradation processes: 2 PHASES

A

Phase 1
* Use of controls and methods for detection of pollutants or biodegradation end-products, detecting and quantifying pollutant-degrading microorganisms
* e.g. 14C labelling, analytical chemistry
* Lab test and determine optimal bioremediation treatments

Phase 2
* Overview examples of how biodegradation processes are worked out, understood
* Once basic processes are understood, they can be utilized in a bioremediation strategy

38
Q

Bioremediation following excavation

A

Enhancing bioremediation with additions, as in in situ

39
Q

Solid soils → Land farming (spread, toill to aerate), Biopiles

i dont understand this slide for real but at least u are seeing the info

A

Slurries via lagoons, vessel reactos (i.e. anaerobic sludge digesters)

40
Q

What was the pollution problem in Eureka?

A

~37 000 L of diesel fuel in 1990

hydrocarbons

41
Q

What was the best method to bioeremediate in Eureka?

A

Fertilizer + water

42
Q

NWT Gold Mine Site - what was the pollutant?

A

Hydrocarbons!

43
Q

NWT Gold Mine: What were the two bioremediation strategies used?

A
  1. Addition of fertilzier and air
  2. Covered biopile to maintain higher temperature
44
Q

Are treating aquifers harder than soil?

A

Yes

45
Q

Why is it harder to treat aquifers than soil? (3)

A
  1. Large area
  2. Flow is slow and unmoving
  3. Oxygen is the limiting element, and the system becomes anaerobic often
46
Q

What are three ways to bioremediate contaminated aquifers?

A
  1. Bioventing of vadose zone soils
  2. Biosparging
  3. Permeable reactive barriers
47
Q

How does bioventing of vardose zone soils work? (3)

A
  • In situ
  • Vacuum applied to bore hole, draws out volatile contaminants
  • Promotes air flow in permeable soils

3 holes, 2 push air down the other is a vaccuum sucking up the fumes

48
Q

How does biosparging work? (3)

A
  • In situ
  • Pumps air or O2 into the contaminates zones to increase aerobic biodegradive activity
  • Requires a porous environment
49
Q

How do permeable reactive barriers work? (4)

A
  • A trench or engineered barrier is placed across ground water flow in a treatment zone
  • The barrier passively captures a plume of contaminants and removes or breaks down the contaminants, releasing uncontaminated water
  • Primary removal methods include
    1. Sorption and precipitation
    2. Chemical reaction
    3. Biodegradation mechanisms
  • only for shallow aquifers
50
Q

Pollution problem in Alberta Tar Sands

What are the issues with the tailing sands and tailing waters?

A
  • Increased ion content, e.g. Na+
  • Alkaline pH
  • Nutrient depleted
  • Residual hydrocarbons
51
Q

Pollution problem in Alberta Tar Sands

What remediation can be used to solve this issue?

A

Phytoremediation

52
Q

What is phytoremediation?

A
  • Exploitation of plants and associated microbes that are capable of bioremediation
  • Huge potential for treating large multi-contaminated sites
  • Efficiency depends on plant-microbe interactions
53
Q

Benefits of phytoremediation (8)

A
  • Wide public acceptance (less so for transgenics)
  • Inexpensive
  • Energy efficient (solar-powered)
  • Can occur in situ
  • Sequester heavy metals and stimulate organic biodegradation
  • Production of biomass for fuel (use of the plants for biofuel)
  • Pioneer species
  • Soil reconstruction
  • Detoxifying the soil via the remediation
54
Q

Pros of phytoremediation (5)

A
  • One of the few methods for removing heavy metals from soil and shallow aquifers
  • Inexpensive
  • Can promote soil regeneration
  • Additional uses for plant material (e.g. biofuels, C sequestration)
  • In some cases, leads to effective stimulation of petroleum breakdown
55
Q

Cons of phytoremediation (5)

A
  • Can be slow remediation (15-100 years)
  • Difficult to predict
  • How to treat multi-contaminated sites? (plants thay can grow with one toxic contaminant, might not be able to grow with more than one, aka site too toxic for plant growth)
  • Contaminant concentration thresholds can be hard to achieve
  • May give a false image of site restoration
56
Q

Phytoremediation summary (4 points)

A
  • Plants contribute to phytoremediation both directly (e.g. accumulation of metals) and indirectly (e.g. stimulation of microbes that degrade organics).
  • Optimizing phytoremediation means increasing plant growth and stimulating microbes that are efficient bioremediators.
  • Phytoremediation can bring additional benefits (e.g. biomass production, habitat restoration) which will assist with its acceptance and utility in the future.
  • A technology still under development!

NRSC 333 (23 decks)

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