Groundwater Pollution - PowerPoint PPT Presentation

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Groundwater Pollution

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Title: Groundwater Pollution


1
Groundwater Pollution
  • Some sample exam questions

2
  • 1. You have just started investigations at a
    hazardous waste site and you discover a drum
    nesta pile of old 200 liter drums and other
    debris. A quick check of the pile shows that it
    remains contaminated with organic chemicals. You
    cannot remove the drums and debris until you get
    further into your site cleanup, but you want to
    cover it for now to prevent rainfall from
    infiltrating the waste and spreading contaminants
    to soil and ground water. You may need to keep it
    covered for as long as a year or two. What type
    of liner material would you specify for covering
    the pile?

3
  • The cover is only needed for a short time.
  • Best would be a flexible membrane liner (some
    type of plastic).
  • It must be able to stay in sunlight (UV).
  • It must be strong and flexible to cover the
    drums.
  • It must be able to stand chemicals.
  • Using clay directly on the waste doesnt work
    because it could soak up waste and would need
    further disposal.

4
  • 2. What is natural attenuation?
  • What happens in natural attenuation?
  • People say it is not a do nothing method. What
    do they mean?

5
  • Natural attenuation is where there is no human
    action to remediate the pollution. The pollution
    is naturally reduced.
  • Monitoring is used to make sure that the
    pollution is being reduced.

6
  • 3. An underground leak (at a 3 m depth) at a gas
    station resulted in the loss of several thousands
    of liters of gasoline into subsoil. The gasoline
    then contaminated the ground water that is 4 m
    below the surface.
  • Give 2 possible remediation techniques for the
    vadose zone and 2 techniques that could be used
    to clean up the ground water.
  • For both the vadose zone and the ground water say
    which one of the two methods you would use and
    also say why you would use them.

7
  • Vadose zone dig up the soil and incinerate, or
    wash etc.
  • - use soil vapor extraction (SVE) to evaporate
    and remove the gasoline.
  • - use bioremediation, adding nutrients, water air
    etc to increase microorganisms.
  • If the volume is small use dig and treat, if the
    volume is big use SVE maybe with bioremediation.

8
  • Groundwater pump and treat with air stripping.
  • - use in-situ bioremediation, adding nutrients,
    air etc to increase microorganisms.
  • In-situ bioremediation is cheaper but takes
    longer.

9
  • 4. Draw a picture of showing possible groundwater
    contamination with DNAPL.
  • What is DNAPL?
  • What methods would you use to remediate this
    contamination?

10
A diagram showing the migration of DNAPLs
11
  • The liquids with very low solubility are called
    non-aqueous phase liquids (or NAPLs)
  • Dense NAPL (DNAPL) is more dense than water. It
    will move down through the groundwater.

12
  • Remediation depends on the contaminant.
  • eg. - could use sorption barriers
  • - add methane, H2 or other electron donor to give
    reductive dechlorination.
  • - deep DNAPL pools need to be removed, maybe
    using heat or detergent to flush out the
    pollutant.

13
  • 5. Draw a picture of showing possible groundwater
    contamination with LNAPL.
  • What is LNAPL?
  • What methods would you use to remediate this
    contamination?

14
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15
  • The liquids with very low solubility are called
    non-aqueous phase liquids (or NAPLs)
  • Light NAPL (LNAPL) is lighter than water. It will
    float on the groundwater.

16
  • Treat the vadose zone and the groundwater.
  • Remove the LNAPL from the surface of the
    groundwater, maybe by bioslurping.
  • Use sparging, bioremediation, SVE etc.

17
  • 6. Draw a picture showing possible groundwater
    contamination with metal.
  • What methods would you use to treat this
    contamination?

18
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19
  • Possible treatments
  • - Dig and treat
  • - Solidification
  • - Enclosing in barriers
  • - Maybe precipitate with Na2S, or other compounds
  • - Use a permeable reactive barrier.

20
  • 7. Draw a diagram of the different electron
    acceptor zones of an oil spill.

21
Draw a diagram of the different electron acceptor
zones of an oil spill.
22
  • 8. How can some metal oxides be used to remove
    organic contaminants from the soil or
    groundwater?

23
  • Organic contaminants can be naturally degraded by
    redox reactions. Mn and Fe-oxides can oxidize
    aromatic pollutants.

24
  • 9. What is the first and most important step of a
    typical soil and/or groundwater remediation
    project?

25
  • The first and most important step of a typical
    soil and/or groundwater remediation project is to
    find out the extent of contamination.
  • Site characterization determines the conditions
    at the site.

26
  • 10. The pollution can occur in groundwater in a
    plume. Give three questions that could be asked
    about the contaminant plume.

27
  • The questions to ask about the contaminant plume
    are
  • Where is the contaminant plume?
  • What is in the plume?
  • How big is the plume?
  • How long has it been there?
  • Where is it going?
  • How fast will it go?

28
  • 11. What is a redox reaction?
  • What do we call the chemical which gains
    electrons?
  • What do we call the chemical which loses
    electrons?

29
  • A redox reaction is a half-reaction of oxidation
    and a half-reaction of reduction.  
  • Both half reactions involve the transfer of
    electrons between the chemicals in the system.
  • The chemical gaining electrons in the
    half-reaction of reduction is the oxidizing
    agent.
  • The chemical which loses electrons in the
    half-reaction of oxidation is the reducing agent.

30
  • 12. Describe the difference between attenuation
    of organic compounds and attenuation of metals.

31
  • The difference between attenuation of organic
    compounds and attenuation of metals is
  • Naturally occurring biodegradation can completely
    convert some organic contaminants to harmless
    products.
  • Metals can only be transformed to forms that are
    less mobile or less toxic.

32
  • 13. Why arent Pump and Treat systems of
    groundwater remediation be used all the time?

33
  • Pump and Treat systems of groundwater
    remediation arent used all the time because they
    are not very successful in removing all
    contaminants.

34
  • 14. Describe two different in-situ remediation
    methods.
  • Include what contaminant each is used for, what
    are some advantages and disadvantages.

35
  • http//www.epa.gov/tio/download/citizens/bioremedi
    ation.pdf
  • http//www.epa.gov/tio/download/citizens/chem-deha
    lo.pdf
  • http//www.epa.gov/tio/download/citizens/insituflu
    shing.pdf
  • http//www.epa.gov/tio/download/citizens/insituthe
    rm.pdf
  • http//www.epa.gov/tio/download/citizens/mna.pdf
  • http//www.epa.gov/tio/download/citizens/citprb.pd
    f
  • http//www.epa.gov/tio/download/citizens/citphyto.
    pdf
  • http//www.epa.gov/tio/download/citizens/citsve.pd
    f

36
  • 15. Describe two different ex-situ remediation
    methods.
  • Include what contaminant each is used for, what
    are some advantages and disadvantages.

37
  • See handout

38
  • 16. How can some metal oxides be used to remove
    organic contaminants from the soil or
    groundwater?

39
  • Organic contaminants can be naturally degraded by
    redox reactions. Mn and Fe-oxides can oxidize
    aromatic pollutants.
  • Another example

40
  • 17. How does sorption affect the movement of
    contaminants through the groundwater?

41
  • Sorption is the attraction of an aqueous chemical
    to the surface of a solid. It involves bonding
    between the contaminant and adsorption receptor
    sites on the solid.
  • Sorption slows the traveling of contaminants
    though the groundwater.
  • Adsorption is the attraction between the outer
    surface of a solid particle and a contaminant.
  • Absorption is the uptake of the contaminant into
    the physical structure of the solid.

42
  • 18. Draw a diagram showing how a reactive barrier
    works.
  • What are some pollutants which can be treated
    with a reactive barrier?

43
  • ABIOTIC AND BIOLOGICALLY MEDIATED ABIOTIC
    ATTENUATION METHODS
  • REACTIVE BARRIERS

example
44
  • 19. What is bioaugmentation?
  • Give an example

45
  • Bioaugmentation involves seeding aquifers with
    microorganisms.
  • For example, adding halorespiring microorganisms
    in anaerobic plumes that contain electron donors
    and chlorinated solvents.
  • The microorganisms should spread and grow and
    increase the natural attenuation capacity.
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