NATIONAL RISK MANAGEMENT
RESEARCH LABORATORY

(Base-Catalyzed Decomposition Process)

TECHNOLOGY DESCRIPTION:

The base-catalyzed decomposition (BCD) process is a chemical dehalogenation technology developed by the National Risk Management Research Laboratory in Cincinnati, Ohio. The process is initiated in a medium-temperature thermal desorber (MTTD) at temperatures ranging from 600 to 950 °F. Sodium bicarbonate is added to contaminated soils, sediments, or sludge matrices containing hazardous chlorinated organics including polychlorinated biphenyls (PCB) and polychlorinated dioxins and furans. Chlorinated contaminants that are thermally desorbed from the matrix are condensed and treated by the BCD process. The BCD process chemically detoxifies the condensed chlorinated organic contaminants by removing chlorine from the contaminants and replacing it with hydrogen.

ETG Environmental, Inc. (ETG), and Separation and Recovery Systems, Inc. (SRS), developed the THERM-O-DETOX® and SAREX® systems and combined them with the BCD process chemistry. The combined process begins by initiating solid- phase dechlorination in the MTTD step (see figure below). In addition to the dechlorination that occurs in the MTTD, organics are thermally desorbed from the matrix, and are condensed and sent to the BCD liquid tank reactor (LTR).

Reagents are then added and heated to 600 to 650 °F for 3 to 6 hours to dechlorinate the remaining organics. The treated residuals are recycled or disposed of using standard, commercially available methods. Treated, clean soil can be recycled as on-site backfill.

ETG has continued to develop the THERM-O-DETOX® system and now offers continuous systems and batch vacuum systems. The batch vacuum system offers greater operational flexibility for removal and destruction of high hazard, high boiling point contaminants to ensure that treatment standards are met. The vapor recovery system can be set up to use noncontact condensers or chillers and additional final polishing steps to meet the most stringent air emission standards.

WASTE APPLICABILITY:

The BCD process can treat soils, sediments, and sludges contaminated with the following chlorinated compounds: halogenated semivolatile organic compounds (SVOC), including herbicides and pesticides; PCBs; pentachlorophenol (PCP) and other chlorinated phenols; and polychlorinated dioxins and furans.

STATUS:

The combined BCD process was demonstrated under the SITE Program at the Koppers Company Superfund site in Morrisville, North Carolina from August through September 1993. The process removed PCP from clay soils to levels below those specified in the record of decision. The process also removed dioxins and furans from contaminated soil to 2,3,7,8-tetrachlorodibenzo-p-dioxins equivalent concentrations less than the concentration specified in the Record of Decision.

ETG is also currently operating the batch vacuum system at a New York State Department of Environmental Conservation cleanup site in Binghamton, New York. Approximately 1500 cubic yards of soil contaminated with herbicides pesticides, dioxins, and furans (F027 waste) are being treated. The Michigan Department of Natural Resources has also approved BCD for a project involving treatment of about 200 cubic yards of F027 soils. At another site, multiple systems will treat soils contaminated with chlorinated volatile organic compounds and high boiling point (800-1150 °F) organic lubricants. The batch vacuum system has also been used to treat sludges at an operating refinery in Puerto Rico and a chemical company in Texas.

For information on the SAREX® system, see the profile for SRS in the Demonstration Program section (ongoing projects).

DEMONSTRATION RESULTS:

The SITE demonstration consisted of four test runs in the MTTD and two test runs in the LTR. Feed soil consisted of a dry, clayey silt and had a residence time of 1 to 2 hours in the MTTD, which was heated to 790 °F to 850 °F. The MTTD off-gases were treated by passing through an oil scrubber, water scrubbers, and carbon filters. The oil from the oil scrubber was transferred to the LTR for BCD treatment. The oil in each LTR test run was batch-processed for 3 to 4 hours at 600 to 630 °F.

Key findings from the SITE demonstration are summarized as follows:

• The MTTD achieved removal efficiencies of 99.97 percent or better for PCP and 99.56 percent or better for total dioxins and total furans.
• The treated soils were well below toxicity characteristic leaching procedure limits for SVOCs.
• Treated soil met the cleanup goals of 95 parts per million PCP in all test runs. Treated soil also met a cleanup goal of 7 micrograms per kilogram 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in all test runs.
• The LTR batch tests reduced PCP concentrations by 96.89 percent or better, and total dioxin and total furan concentrations by 99.97 percent or better.

FOR FURTHER INFORMATION:

EPA PROJECT MANAGER:
Terrence Lyons
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7589
Fax: 513-569-7676

TECHNOLOGY DEVELOPER CONTACTS:
George Huffman
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive, MS-445
Cincinnati, OH 45268
513-569-7431
Fax: 513-569-7549

Yei-Shong Shieh or Steven Detwiler
ETG Environmental, Inc.
16 Hagerty Boulevard
West Chester, PA 19382-7594
610-431-9100
Fax: 610-431-9140