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 doesn’t 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 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 7

8. 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 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 • 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 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