(Anaerobic-Aerobic Sequential Bioremediation of PCE)
ABB Environmental Services, Inc. (ABB-ES), has demonstrated that sequential anaerobic-aerobic biodegradation of tetrachloroethene (PCE) is feasible under the proper conditions. The anaerobic process can dechlorinate PCE completely; however, dechlorination of the least-chlorinated ethenes (1,2-dichloroethene [DCE] and vinyl chloride [VC]) is the slowest step in this process. Of the chlorinated ethenes, VC is the most amenable to treatment by aerobic cometabolic processes. Therefore, a two-step process is thought to be the most efficient treatment methodology to address highly chlorinated solvents.
The first step in the ABB-ES technology is anaerobic biodegradation, which rapidly dechlorinates PCE and trichloroethene (TCE) to produce DCE and VC. Since the anaerobic dechlorination of DCE and VC to ethene can be quite slow, a second, aerobic biodegradation step is implemented that more quickly completes the remediation process. The schematic diagram below illustrates this technology.
This technology removes PCE, TCE, DCE, and VC from groundwater.
This technology was accepted into the SITE Emerging Technology Program in July 1994. ABB-ES will field-test its technology by creating and maintaining the proper in situ conditions for chlorinated ethene degradation in an aquifer. To achieve this goal, ABB-ES will test methods of carbon and mineral nutrient injection and delivery into an aquifer contaminated with PCE or TCE. Groundwater chemical conditions will be monitored within and downgradient of the anaerobic treatment zone to gauge the efficiency of the anaerobic process. If volatile organic compound analyses show that dechlorination of less-chlorinated ethenes is very slow under anaerobic conditions, oxygen and methane will be added to the groundwater to stimulate aerobic degradation by indigenous methanotrophic bacteria.
EPA PROJECT MANAGER:
Ronald Lewis
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7856
Fax: 513-569-7105
TECHNOLOGY DEVELOPER CONTACT:
Willard Murray
ABB Environmental Services, Inc.
Corporate Place 128
107 Audubon Road
Wakefield, MA 01880
617-245-6606
Fax: 617-246-5060