Accession Number:

ADA499385

Title:

In Situ Catalytic Groundwater Treatment Using Pd-Catalysts and Horizontal Flow Treatment Wells

Descriptive Note:

Final rept.

Corporate Author:

NAVAL FACILITIES ENGINEERING SERVICE CENTER PORT HUENEME CA

Report Date:

2007-02-01

Pagination or Media Count:

270.0

Abstract:

The U.S. Environmental Protection Agency EPA estimated in 1996 that approximately 70 of the 8,336 Department of Defense DoD sites requiring cleanup had contaminated groundwater, usually from chlorinated solvents such as trichloroethylene TCE and tetrachloroethylene PCE. Palladium Pd catalysis is a rapid destruction method that, in the presence of hydrogen gas, transforms many chlorinated ethylenes into ethane and some other halogenated volatile organic compounds VOCs into their respective hydrocarbon compounds. The dechlorination reactions for chlorinated ethylenes are complete and rapid and occur in water under ambient temperature, pH and pressure conditions. Hydrogen gas is used as the reducing agent, with residence times on the order of minutes. Catalytic contaminant destruction in a one-pass process has many potential advantages such as eliminating the secondary waste stream created by other processes that transfer contaminants to another medium e.g. air or activated carbon. The technology is also effective in areas of high contaminant concentrations making it applicable to source control. The objective of this project was to demonstrate the feasibility of catalytic destruction of chlorinated VOCs in groundwater using reactors containing palladium-coated beads that were operated in-situ within two previously established horizontal flow treatment wells HFTWs. Although installation of the reactors inside the treatment wells could be possible in a full scale application, it is not recommended due to complications associated with installing feed lines for backflushing and regenerating reactors coupled with high costs for removing reactors from the wells for maintenance, leak checks, etc.

Subject Categories:

  • Water Pollution and Control
  • Organic Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE