Lawrence Livermore National Laboratory’s Environmental Restoration Division has deployed two systems on site that facilitate treatment of groundwater contaminated with chlorinated hydrocarbons and tritium. The systems use catalytic reductive dehalogenation (CRD), a process developed in collaboration with researchers at Stanford University, to break the molecular structure of contaminants like trichloroethylene and perchloroethylene. CRD by dissolved hydrogen in the presence of a catalyst yields environmentally harmless ethane or methane and free chloride ion. The process does not produce dangerous intermediate chlorinated compounds, such as vinyl chloride.

LLNL deployed the first of the units in September 1998, placing the closed-loop treatment system within a dual-screened well. Groundwater contaminated with tritium and chlorinated hydrocarbons (up to 5 parts per million, primarily TCE) is extracted from a low screened section. After hydrogen is injected, the water passes through palladium catalyst material in stainless steel cylinders before reinjection into the subsurface through an upper screened section.

The rapid reaction rates enable the treatment to occur in a closed-loop system, keeping the tritium contamination below ground to attenuate via radioactive decay. This in-well configuration is advantageous in instances where treatment of contaminated groundwater in surface facilities would require enhanced safety measures. The system can treat approximately 3 gallons of water per minute, though the permeability of the surrounding soils is so low that only about 1 gallon per minute is available.

A second unit was activated in September 2000 to meet a regulatory milestone. In a location where contaminant concentrations are 50 to 100 percent higher than at the first installation, this unit functions aboveground, served by two extraction wells and two injection wells. This configuration—which allows for easier construction and maintenance, faster throughput rates, and round-the-clock operation—is engineered with physical and operational safety features. Both systems’ destruction efficiency for 2000 was over 90%.


For further information on CRD, contact Hannibal Joma, DOE Oakland Operations, (925) 422-0830, hannibal.joma@oak.doe.gov or Bob Bainer, Lawrence Livermore National Laboratory, (925) 422-4635, bainer1@llnl.gov. Companies interested in commercializing CRD can contact Catherine Elizondo, Business Development Specialist, at (925) 422-0801, elizondo1@llnl.gov or Lawrence Livermore National Laboratory, 7000 East Avenue, L-795, Livermore, CA 94550.