Bioremediation-From the Lab to the Field

1
Bioremediation-From the Lab to the Field
Mitch Lasat, Ph.D. NCER/ORD
1
2
Presentation Outline

• What is Bioremediation?
• Why Bioremediation works?
• Contaminants amenable to Bioremediation
• Limiting factors (why bioremediation doesnt
  work?)
• Engineering strategies for Bioremediation
• Is bioremediation a hot research topic for the
  EPA?
• Bioremediation research

2
3
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
4
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)

4
5
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
  

5
6
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

6
7
Factors that limit the potential for
Bioremediation (why Bioremediation doesnt work)

• 1) Contaminant-related limitations
• Synthetic vs. natural contaminants
• -bioremediation potential greater for
  natural compounds
• Physical characteristics
• -density, Henrys constant, solubility,
  octanol/water partition coefficient
• Molecular structure of the contaminant
• extent of chlorination, linear vs. branched
  structure, saturated vs.
• unsaturated compounds

7
8
Factors that limit the potential for
Bioremediation (why Bioremediation doesnt work)

• 2) Environmental conditions
• Hydrogeology permeability/hydraulic
  conductivity, heterogeneity,
• fracture bed rocks, soil properties, pH
• Nutrients CNP-100101
• 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

8
9
Engineering Strategies for Bioremediation

• Intrinsic bioremediation/natural attenuation
• Enhanced/engineered bioremediation
• -addition of nutrients, oxygen
• Bioaugmentation
• -introduction of appropriate organisms

9
10
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)

10
11
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

11
12

• Bioremediation research I

• ORDs 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

12
13

• 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

13