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Bioremediation-From the Lab to the Field. Mitch Lasat, Ph.D. NCER/ORD. 1. Presentation Outline. What is Bioremediation? Why Bioremediation works? Contaminants amenable to Bioremediation Limiting factors (why bioremediation doesn’t work?) Engineering strategies for Bioremediation

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Bioremediation-From the Lab to the Field

Mitch Lasat, Ph.D.

NCER/ORD

1

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Presentation Outline

  • What is Bioremediation?
  • Why Bioremediation works?
  • Contaminants amenable to Bioremediation
  • Limiting factors (why bioremediation doesn’t work?)
  • Engineering strategies for Bioremediation
  • Is bioremediation a “hot” research topic for the EPA?
  • Bioremediation research

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What is Bioremediation?

  • the use of biota to degrade/mitigate environmental contamination

-bioremediation- by microorganisms (soil, groundwater-organic contaminants)

-phytoremediation- by plants (mostly soil and surface water)

3

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Why Bioremediation works?

  • microorganisms obtain energy for growth by degrading organic contaminants

in an enzyme-mediated process- direct metabolism

-aerobic biodegradation of BTEX in the presence of an oxygenase (Pseudomonas)

  • some enzymes are not very specific and in addition to the growth substrate

transform other compounds-cometabolism

-oxygenases are not very substrate-specific and can also degrade TCE

(however TCE cannot be used as a growth substrate)

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Contaminants amenable to Bioremediation I

  • Hydrocarbons:

- BTEX (aerobic and anaerobic biodegradation)

- PAH (less amenable)

- aerobic degradation via cometabolism

  • - anaerobic biodegradation (naphtalene-denitrification)
  • Chlorinated Aliphatic Hydrocarbons
  • - aerobic electron donor (DCM, CM, DCA)
  • - anaerobic electron donor (TCE, DCE)
  • - anaerobic acceptor (PCE, TCE)- dehalorespiration
  • - cometabolism (aerobic, anaerobic-reductive dechlorination)
  • Chlorinated aromatic hydrocarbons
  • - PCB (in general bioremediation recalcitrant)
  • -aerobic, less chlorinated
  • -anaerobic (dehalorespiration)
  • - PCP; aerobic, anaerobic (groundwater-reductive dechlorination)
  • - Dioxins; highly resistant to Bioremediation

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Contaminants amenable to Bioremediation II

  • Pesticides

-chlorinated; highly resistant to aerobic transformation

-phosphorus based and carbamate; quickly hydrolyzed

-triazine; biodegradable

  • Explosives
    • -biotransformation is partial (TNT) or slow (RDX)
  • Inorganics

-bacterial reduction of Hg2+ to Hg0

-bacterial reduction of Cr6+ to Cr3+

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Factors that limit the potential for Bioremediation

(why Bioremediation doesn’t work)

  • 1) Contaminant-related limitations:
  • Synthetic vs. natural contaminants

-bioremediation potential greater for natural compounds

  • Physical characteristics

-density, Henry’s constant, solubility, octanol/water partition coefficient

  • Molecular structure of the contaminant
    • extent of chlorination, linear vs. branched structure, saturated vs.
    • unsaturated compounds

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Factors that limit the potential for Bioremediation

(why Bioremediation doesn’t work)

  • 2) Environmental conditions:
  • Hydrogeology: permeability/hydraulic conductivity, heterogeneity,

fracture bed rocks, soil properties, pH

  • Nutrients: C:N:P-100:10:1
  • Electron acceptor: oxygen (3 parts of oxygen to converts 1 part of

hydrocarbon to CO2), nitrate, sulfate, ferric iron

3) Microorganisms presence:

  • Assessment of microbial activity, introduced microorganisms

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Engineering Strategies for Bioremediation

  • Intrinsic bioremediation/natural attenuation
  • Enhanced/engineered bioremediation

-addition of nutrients, oxygen

  • Bioaugmentation

-introduction of appropriate organisms

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Phytoremediation

  • Phytoextraction (removal/extraction of toxic metals- Pb)
  • Phytodegradation (organics degradation in roots and shoots-

TPH, PAHs, BTEX, pesticides, CAHs)

  • Phytovolatilization (CAHs, Hg, Se)
  • Evapotranspiration/Hydraulic control (plume reduction)

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Is bioremediation a “hot” research topic for the EPA?

  • Cross-agency research advisory workgroup for Goal 3; Bioremediation- a

priority technology for remediation of contaminated sediments,

groundwater and soil

  • ORD GOAL 3 MYP-long-term goal oriented with annual progress measured

by completion of APG/APM-of the approximately 70 remediation-related

APMs, approximately half pertain to bioremediation:

- Report on biodegradation of PAHs in sediments

- Report on solvent-enhanced residual biotreatment of residual DNAPL

- Develop and evaluate microbial populations for effective TCE biodegradation

- Develop and evaluate cost-effective methods for nutrient mixing and delivery for bioremediation of chlorinated aliphatic hydrocarbons

- Synthesis report on 5 DNAPL remediation technologies

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Bioremediation research I

  • ORD’s Goal 3research program is designed to provide a better understanding

of the traditional risk management options (dredging, capping, pump and

treat), and to investigate alternative options (bioremediation, MNA)

  • Problem-driven research program, supporting research needs of:
  • - Office of Solid Waste
  • - Superfund
  • - Leaking Underground Storage Tank Corrective Action
  • - Oil Spills
  • Contacts: NPD-Randy Wentsel

NRMRL-Trish Erickson

NCER-Mitch Lasat

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Bioremediation research II

  • NCER Bioremediation research:
  • - 1997-2001; several RFAs on Bioremediation and Phytoremediation
  • - 2001; HSRC program was recompeted, research focus on contaminated
  • sediments, VOC-contaminated groundwater, mine wastes,
  • phytoremediation
  • http://es.epa.gov/ncer/grants/
  • Case studies/performance data:

http://clu-in.org/techfocus/

  • - site general information
  • - contaminants
  • - site hydrology
  • - media
  • - cleanup goals
  • - technology used
  • - results/costs
  • - lessons learned

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