Base-Catalyzed Dechlorination (BCD) Process
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. BCD is initiated in a medium temperature thermal desorber (MTTD), at temperatures ranging from 600 to 800 °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. The BCD process then chemically detoxifies the chlorinated organic contaminants by removing chlorine from the contaminants and replacing it with hydrogen. The result is a clean, inexpensive, permanent remedy where all process residuals (including dehalogenated organics) are recyclable or recoverable.
ETG Environmental, Inc. (ETG), and Separation and Recovery Systems (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 ther-mally 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 4 to 6 hours to dechlorinate the remaining organics. The treated residuals are recycled or disposed of using standard, commercially available methods, including solvent reuse and fuel substitution. Treated, clean soil can be recycled as on-site backfill.
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)
· Polychlorinated dioxins and furans
STATUS:
The combined BCD process was successfully demonstrated at the Koppers Company Superfund site in Morrisville, North Carolina, from August through September 1993. The process removed PCP and polychlorinated dioxins and furans from clay soils to levels below those specified in the record of decision. As a result, EPA Region 4 approved BCD for the full-scale site remediation.
For information on the SAREX® system, see the profile for SRS in the Demonstration Program section (ongoing projects).
DEMONSTRATION RESULTS:
The demonstration consisted of four test runs in the MTTD and two test runs in the LTR. Feed soil consisted of a dry, clayey silt which was processed at a rate of 250 pounds per hour in the MTTD at 800 °F; retention time was approximately 1 hour. The oil in each LTR test run was batch-processed for six hours at 650 °F.
Based on preliminary analytical results, key findings from the SITE demonstration are summarized as follows:
· The MTTD achieved removal efficien-cies of 99.97 percent or better for PCP and 99.56 percent or better for total dioxins and total furans.
· All SVOCs in treated soil were well below toxicity characteristic leaching procedure limits.
· Treated soil met the cleanup goals of 95 parts per million PCP in all test runs, and 7 micrograms per kilogram 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in test runs where processed soils contained sodium bicarbonate additive.
· 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:
Carl Brunner
U.S. EPA
National Risk Management Research
Laboratory
26 West Martin Luther King Drive, MS-443
Cincinnati, OH 45268
513-569-7655
Fax: 513-569-7787 or 7677
Yei-Shong Shieh or Steven Detwiler
ETG Environmental, Inc.
660 Sentry Parkway
Blue Bell, PA 19422
610-832-0700
Fax: 610-828-6976