Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Biodegradation study of diesel and surrogate compounds of


Published on

A laboratory study of biodegradati

Published in: Education
  • Be the first to comment

Biodegradation study of diesel and surrogate compounds of

  1. 1. Biodegradation Study of Diesel and Surrogate Compounds of Diesel Todd R. Crawford Crawford Independent Analysts
  2. 2. Biodegradation <ul><li>…the biologically catalyzed reduction in complexity of chemicals… (Alexander 1994) </li></ul><ul><li>Organic compounds are frequently biodegraded to inorganic chemicals – mineralization </li></ul><ul><li>A desirable approach to site remediation </li></ul>
  3. 3. Incomplete Biodegradation <ul><li>A threshold concentration is reached </li></ul><ul><li>Remaining material cannot be biodegraded by: </li></ul><ul><ul><li>Aeration, or </li></ul></ul><ul><ul><li>Addition of nutrients </li></ul></ul><ul><li>This phenomenon is seen for most organic chemicals biodegrading in soil </li></ul>
  4. 4. Causes of Incomplete Biodegradation <ul><li>Contaminant may be adsorbed into micropores </li></ul><ul><li>Contaminant may be adsorbed into soil organic carbon </li></ul><ul><li>Microorganisms may be inhibited by some biodegradation byproduct </li></ul><ul><li>Amount of contaminant may not be sufficient to support biological activity </li></ul><ul><li>Remaining contaminant may not be composed of biodegradable material </li></ul>
  5. 5. Diesel Fuel <ul><li>Several thousand chemicals </li></ul><ul><li>Mostly carbon and hydrogen (hydrocarbons) </li></ul><ul><li>Aliphatics </li></ul><ul><ul><li>Straight chain alkane </li></ul></ul><ul><ul><li>Branched chain alkane </li></ul></ul><ul><li>Aromatics </li></ul><ul><ul><li>Polycyclic Aromatic Hydrocarbons (PAHs) </li></ul></ul>
  6. 6. GC-FID trace of diesel fuel
  7. 7. Site <ul><li>Rhode Island </li></ul><ul><li>Former petroleum distribution terminal </li></ul><ul><li>Approximately 100 acres </li></ul><ul><li>Approximately 150,000 cy diesel contaminated soil </li></ul><ul><li>Remediation goal 500 ppm TPH </li></ul><ul><li>Ex situ biodegradation </li></ul>
  8. 8. Incomplete Biodegradation <ul><li>Biodegradation ceased around 1000 ppm TPH </li></ul><ul><li>Weekly tilling (aeration) did not stimulate biodegradation </li></ul><ul><li>Soil amendments did not stimulate biodegradation </li></ul><ul><li>Holding up the project! </li></ul>
  9. 9. Soils <ul><li>U2A – treatment soil </li></ul><ul><ul><li>Silty sand from shore area </li></ul></ul><ul><ul><li>Initial TPH concentration ~3000 ppm </li></ul></ul><ul><ul><li>Final TPH concentration ~1000 ppm </li></ul></ul><ul><ul><li>Air-dried for 24 hours </li></ul></ul><ul><ul><li>Sieved </li></ul></ul><ul><ul><li>Air-dried for 24 hours </li></ul></ul><ul><ul><li>Stored in 1-Liter glass jars in refrigerator until used </li></ul></ul>
  10. 10. Biodegradation Study <ul><li>Is the petroleum sequestered in the soil – not available to biodegradation? </li></ul><ul><li>Is the remaining petroleum not biodegradable? </li></ul>
  11. 11. TPH Redistribution Experiment <ul><li>If petroleum is sequestered in soil, then let’s redistribute it… </li></ul><ul><li>Out of soil pores onto soil surface where it is bioavailable… </li></ul><ul><li>Out of soil onto another soil where it may be more bioavailable… </li></ul>
  12. 12. Redistribution setup <ul><li>U2A soil </li></ul><ul><li>U2A soil shaken with methylene chloride and evaporated at room temperature </li></ul><ul><li>U2A soil extract (methylene chloride) transferred to sandy soil and evaporated at room temperature </li></ul><ul><li>Diesel fuel in sand </li></ul>
  13. 14. Indications <ul><li>Little or no significant biodegradation of the remaining diesel in: </li></ul><ul><ul><li>U2A soil without redistribution </li></ul></ul><ul><ul><li>U2A soil with redistribution </li></ul></ul><ul><ul><li>Sand with U2A soil extract </li></ul></ul><ul><li>Biodegradation did occur for diesel in sand – the setup should biodegrade the contaminant </li></ul>
  14. 15. Surrogate Biodegradation Experiment <ul><li>Is the remaining petroleum non-biodegradable – not bioavailable? </li></ul><ul><li>Add surrogates of diesel to soil </li></ul><ul><li>Add surrogates of diesel to soil extract in another soil </li></ul>
  15. 16. Selected Diesel Surrogates <ul><li>Hexadecane – straight C-16 alkane </li></ul><ul><li>Octacosane – straight C-28 alkane </li></ul><ul><li>Pristane – branched C-19 alkane </li></ul><ul><li>Squalane – branched C-30 alkane </li></ul><ul><li>Phenanthrene – C-14 PAH </li></ul><ul><li>100 ppm of each surrogate added to soils </li></ul>
  16. 20. Observations <ul><li>Branched alkanes are biodegrading slowly </li></ul><ul><li>Longer alkanes are biodegrading slower than shorter alkanes </li></ul><ul><li>Phenanthrene is biodegrading faster than other surrogates!? </li></ul>
  17. 21. Conclusions <ul><li>Biodegradation is inhibited in the site soils by a chemical that is transferred with the methylene chloride extract </li></ul><ul><li>And/Or </li></ul><ul><li>Most of the remaining material is branched alkanes </li></ul>
  18. 22. Acknowledgements <ul><li>Jim Smith and Les Eng, Trillium Inc. </li></ul><ul><li>John E. Ross, CTEH LLC </li></ul><ul><li>José A. Amador, URI </li></ul>