In Situ Remediation Basics

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  • ARS Technologies 2000
  • ARS Technologies 2000 For injection to be successful you need to pick the right chemistry and get good delivery of the injected fluid
  • Hydrogeology: to design good delivery system Geochemistry: is the site aerobic, anaerobic Contaminants: which chemistry is best Microbial population: are the right bacteria there, are they healthy ARS Technologies 2000
  • Metals: to bind up the metals so they do not migrate Petroleum VOCs: can use biodegradation, either aerobic or anaerobic; can use oxidation; can inject heat to volatilize Chlorinated VOCs: can use anaerobic biodegradation; can use oxidation; can use chemical reduction SVOCs and PCBs: typically use oxidation ARS Technologies 2000
  • Successful remediation requires understanding the contaminants Define the source area, the dissolved plume, what are the concentrations Are the contaminants being degraded by native microbes, can the degradation be enhanced by injection ARS Technologies 2000
  • ARS Technologies 2000 Types of in-situ remediation Chemical reduction is using zero valent iron
  • Direct oxidation reduces contaminants to basic materials; water, chlorine, carbon dioxide, ethene/ethane/methane gases ARS Technologies 2000
  • Chemical reduction: a patented method (by Adventus) of remediation using zero valent iron ARS Technologies 2000
  • For petroleum: adding oxygen to the ground to enhance the natural bacteria that eat the hydrocarbons Oxygen release products: like ORC, PermeOx, EHC-O ARS Technologies 2000
  • Sulfate reducing bacteria can reduce petroleum products Dehalogenating bacteria can break down chlorinated hydrocarbons when sufficient hydrogen is present Typical hydrogen sources are complex carbon compounds such as fatty acids, oils, sugars ARS Technologies 2000
  • ARS Technologies 2000
  • Objective is long-term creation of hydrogen that feeds the bacteria that will break down the contamination Sugars like molasses are inefficient sources; can take 5 times as long, and can stop degrading midway, leaving vinyl chloride behind ARS Technologies 2000
  • Dehalococcoides etheneogenes (DHC) is only known halorespirer that degrades ethenes and ethanes ARS Technologies 2000
  • ARS Technologies 2000
  • In Situ Remediation Basics

    1. 1. In-Situ Remediation Applications
    2. 2. <ul><li>Key Factors for Success </li></ul><ul><ul><li>The Right Chemistry </li></ul></ul><ul><ul><ul><li>fundamental understanding of geochemistry and microbiology to pick right chemistry </li></ul></ul></ul><ul><ul><li>Good Delivery </li></ul></ul><ul><ul><ul><li>contact with the contamination </li></ul></ul></ul><ul><ul><ul><li>intensity of the delivery and distribution </li></ul></ul></ul>
    3. 3. <ul><li>Understand the Site </li></ul><ul><ul><li>Hydrogeology </li></ul></ul><ul><ul><li>Geochemistry </li></ul></ul><ul><ul><li>Contaminants </li></ul></ul><ul><ul><li>Microbial populations </li></ul></ul><ul><li>A good understanding of contaminant source, contaminant migration, means a better design for remediation plan </li></ul>
    4. 4. <ul><ul><li>Metals </li></ul></ul><ul><ul><ul><li>Objective: change the valence state to bind metals and restrict migration </li></ul></ul></ul><ul><ul><li>VOCs: </li></ul></ul><ul><ul><ul><li>Petroleum: can use biodegradation, either aerobic (oxygen) or anaerobic (sulfate); oxidation; inject heat to volatilize and enhance extraction </li></ul></ul></ul><ul><ul><ul><li>Chlorinated: anaerobic bio; oxidation; chemical reduction </li></ul></ul></ul><ul><ul><li>SVOCs: oxidation </li></ul></ul><ul><ul><li>PCBs: oxidation </li></ul></ul>
    5. 5. <ul><li>Concentrations </li></ul><ul><ul><li>Define source area </li></ul></ul><ul><ul><li>Delineate dissolved plume </li></ul></ul><ul><li>Transformations </li></ul><ul><ul><li>Degradation products of solvents indicate the types of bacteria present, can they be utilized or need to be augmented </li></ul></ul><ul><ul><ul><li>Will there be complete degradation to ethene/ethane, a stall at cis-DCE, or a vinyl chloride build-up </li></ul></ul></ul>
    6. 6. <ul><li>Chemical Oxidation </li></ul><ul><li>Chemical Reduction </li></ul><ul><ul><li>(zero valent iron) </li></ul></ul><ul><li>Aerobic Bioremediation </li></ul><ul><li>Anaerobic Bioremediation </li></ul><ul><li>Thermal (steam) injection </li></ul><ul><li>Metals Stabilization </li></ul>
    7. 7. <ul><li>Chemical Oxidation </li></ul><ul><ul><li>Direct chemical destruction of volatile organics, petroleum and chlorinated hydrocarbons </li></ul></ul><ul><ul><li>Typical oxidants: </li></ul></ul><ul><ul><ul><li>Potassium and sodium permanganate </li></ul></ul></ul><ul><ul><ul><li>Sodium persulfate </li></ul></ul></ul><ul><ul><ul><li>Hydrogen peroxide, Fenton’s chemistry </li></ul></ul></ul><ul><ul><ul><li>Ozone </li></ul></ul></ul><ul><ul><li>Typical response time: immediate to 4 months </li></ul></ul>
    8. 8. <ul><li>Chemical Reduction </li></ul><ul><ul><li>Direct destruction of volatile organics through abiotic reduction </li></ul></ul><ul><ul><li>Zero valent iron (ZVI) </li></ul></ul><ul><ul><ul><li>Typically injected, placed as a reactive wall or barrier </li></ul></ul></ul><ul><ul><ul><li>Commonly used for chlorinated hydrocarbons </li></ul></ul></ul><ul><ul><li>Typical response time: immediate to years </li></ul></ul>
    9. 9. <ul><li>Aerobic Bioremediation </li></ul><ul><ul><li>Addition of oxygen source to feed bacteria that consume petroleum hydrocarbons </li></ul></ul><ul><ul><ul><li>Air sparging </li></ul></ul></ul><ul><ul><ul><li>Oxygen release products </li></ul></ul></ul><ul><ul><ul><li>Oxygenated water injection </li></ul></ul></ul><ul><ul><li>Typical effective treatment: 1 to 6 months, or the length of sparging period </li></ul></ul>
    10. 10. <ul><li>Anaerobic Bioremediation </li></ul><ul><ul><li>Sulfate reduction of petroleum </li></ul></ul><ul><ul><ul><li>Magnesium sulfate (Epsom salt, EAS®), gypsum </li></ul></ul></ul><ul><ul><li>Chlorinated hydrocarbon enhanced reductive dechlorination (ERD) </li></ul></ul><ul><ul><ul><li>Adding hydrogen source to feed bacteria </li></ul></ul></ul><ul><ul><ul><ul><li>Fatty acids </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Edible oil </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Sodium/ethyl lactate esters </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Molasses and sugars </li></ul></ul></ul></ul><ul><ul><li>Typical effective treatment: 6 to 24 months </li></ul></ul>
    11. 11. <ul><li>Why enhanced? </li></ul><ul><li>Aquifers are sometimes limited by carbon (or food) source for bacteria </li></ul><ul><li>In some instances, the proper bacteria (e.g. dehalogenators) are not present </li></ul><ul><ul><li>Can bioaugment with D ehalococcoides ethenogenes </li></ul></ul>
    12. 12. <ul><li>Lactates, fatty acids , edible oils ferment anaerobically: </li></ul><ul><ul><li>Hydrogen is produced plus a new shortened fatty acid (lactic, linoleic, palmitic, propionitic acids); the shortened fatty acid is then cleaved, forming more hydrogen and acetic acid. The acetic acid breaks down to methane and carbon dioxide </li></ul></ul><ul><ul><li>Breakdown product acids degrade under lower hydrogen partial pressures, serve as a hydrogen storage, provide a longer hydrogen source </li></ul></ul><ul><ul><li>Does not overstimulate (typical problem when using sugars): </li></ul></ul><ul><ul><ul><li>Sugar overstimulates methanogens; much slower breakdown, incomplete degradation, excess methane gas produced (health hazard) </li></ul></ul></ul>
    13. 13. <ul><li>Anaerobic microorganisms that degrade chlorinated organics (halorespirers) use the hydrogen as an electron donor and the chlorinated organics as electron acceptors </li></ul><ul><li>First notice a decline in parent material (PCE, TCE, TCA) with a corresponding increase in cis-DCE; then vinyl chloride. Then degradation products are degraded, resulting in ethenes/ethanes. </li></ul>
    14. 14. <ul><li>Can use a mixture of hydrogen source plus ZVI </li></ul><ul><ul><li>Combines anaerobic bioremediation and chemical reduction (from ZVI) </li></ul></ul><ul><li>Less likely to form vinyl chloride </li></ul><ul><li>Adventus holds patent to add ZVI to carbon amendment </li></ul>
    15. 15. <ul><li>Volume, rates of injection are monitored for each well for the duration of the injection </li></ul>
    16. 16. Direct Push (Geoprobe) Injection

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