From laboratory study to full-scale application: Treating groundwater for TCE removal using catalyzed reductive dechlorination


Martin Reinhard,, Dept. Civil and Env. Eng, Stanford University, Stanford, CA 94305-4020, Gary D. Hopkins,, Dept. Civil Env. Eng, Stanford University, Stanford, CA 94305-4020, Jeff Cunningham,, Dept. of Civil & Environmental Engineering, University of South Florida, 4202 E. Fowler Ave., ENB 118, Tampa, FL 33620, and Carmen A. Lebrón,, ESC411, NFESC, 1100 23rd. Ave., Port Hueneme, CA 93043.
Chlorinated solvents such as trichloroethylene (TCE) and tetrachloroethylene (PCE) and their biological metabolites are difficult to treat groundwater contaminants. Palladium catalyzed reductive dechlorination (CRD) of chlorinated ethylenes has been studied in the laboratory and demonstrated in the field. CRD efficiently destroys the contaminants, is safe and requires only a small foot-print. This presentation summarizes the transformation mechanism, catalyst fouling and regeneration and experiences with full-scale implementation. Information from laboratory experiments was used for the design and operation of full-scale systems but found inadequate for specifying requirements for process control, reactor maintenance and safety. The level of robustness required for full-scale operation is difficult to gauge from laboratory and pilot studies. A CRD reactor for treating chlorinated ethylenes was tested at the Edwards AFB in Southern California. Operating and biofouling control conditions were adapted to the nearly anaerobic groundwater. Long-term removal TCE from groundwater containing nearly 1 mg/L TCE was 99.2%.