Lee Clapp and Andrew Ernest Texas A&M University - Kingsville Presented at HBCU/MI Kickoff Meeting

1. A Permeable Reactive Barrier Remediation Technology Using Membrane-Attached Methanotrophic Biofilms HBCU/MI Lee Clapp and Andrew Ernest Texas A&M University - Kingsville Presented at HBCU/MI Kickoff Meeting March 10-11, 2003

2. Problem: Contaminated groundwater due to improper disposal of chlorinated solvents

3. Magnitude of Problem: HBCU/MI • DOE • 10,500 identified contaminated sites (1996) • 25% contaminated with chlorinated solvents. • Estimated cost of remediation - $63 billion • Estimated time for remediation - 75 years NEED - Development of technologies to reduce chlorinated solvent remediation costs. (Ref: EPA-542-R-96-005)

4. Hollow-Fiber Membrane Semi-Passive Permeable Reactive Barrier DCE CO2 + Cl- VC CO2 + Cl- CH4 Water Table CH4 Groundwater flow CH4 Confining Contaminant Biofilm Bacterium Layer Plume Hollow Fiber Membrane Overall Research Goal HBCU/MI To develop a semi-passive permeable reactive barrier (PRB) remediation technology that fosters biological destruction of chlorinated organic compounds by the controlled delivery of soluble methane & oxygen gas to membrane-attached methanotrophic biofilms in the subsurface.

5. Membrane-attached methanotrophic biofilm HBCU/MI

6. gas added to membranes in wells direction of groundwater flow Use of In-situ hollow-fiber membranes for passive gas transfer to subsurface

7. air compressor compressed CH4 tank TCE Cl- TCE plume CH4 CO2 CH4 O2

8. Research objectives: HBCU/MI • Evaluate effect of inter- and intra-well pumping on groundwater flow patterns & well capture zones. • Quantify effect of copper loading on “soluble methane monooxygenase” (sMMO) activity within membrane-attached biofilms.

9. Groundwater modeling studies: HBCU/MI • Phase 1: Characterize relationship between well-spacing, inter- and intra-well pumping rate, and capture zone. • Phase 2: Characterize relationship between well-spacing, inter- and intra-well pumping rate, and DCE removal efficiency.

10. Capture zone without pumping Unpumped Well Unpumped Well

11. Capture zone with inter-well pumping injection well extraction well injection well extraction well

12. Conceptualized flow field capture vs. number of wells & pumping rates HBCU/MI

13. sMMO expression studies: HBCU/MI • Cultivate membrane-attached methanotrophic biofilms in simple chemostat systems. • Characterize sMMO expression as a function of copper loading rate.

14. sMMO pMMO pMMO Problem with copper sMMO repression HBCU/MI low copper high copper Type II Type I

15. growing cells utilizing CH4 non-growing cells cometabolizing TCE inactivated cells adsorbing copper CH4 & O2 continuous flux of new cells erosion Biofilm stratification may select for sMMO membrane

16. flux of new cells SEM of biofilm cross-section

17. Membrane-attached biofilms

18. Expected Results HBCU/MI sMMO DCE degradation rate pMMO YJCH4 /JCU

19. Deliverables: HBCU/MI • Fundamental engineering data required to assess the feasibility of the semi-passive PRB technology. • Technical reports and peer-reviewed articles on the science & engineering of the technology.