KAI Antenna System
KAI TECHNOLOGIES, INC./
BROWN AND ROOT ENVIRONMENTAL
(Radio Frequency Heating)
TECHNOLOGY DESCRIPTION:
Radio frequency heating (RFH) is an in situ process that uses electromagnetic energy to heat soil and enhance soil vapor extraction (SVE). The patented RFH technique, developed by KAI Technologies, Inc. (KAI), uses an antenna-like applicator inserted in a single borehole to heat a volume of soil. Large volumes of soil can be treated by RFH employing a control system and an array of applicators. When energy is applied by the applicator to the soil, heating begins near the borehole and proceeds radially outward. This technique can achieve a soil temperature in excess of 250 °C.
RFH enhances SVE in two ways: (1) contami-nant vapor pressures are increased by heating; and (2) soil permeability is increased by drying. Extracted vapor can then be treated by a variety of existing technologies.
WASTE APPLICABILITY:
The RFH technique has been tested using pilot-scale vertical and horizontal antenna orientations to remove petroleum hydrocarbons and volatile and semivolatile organics from soils. The technology is most efficient in subsurface areas with low groundwater recharge. In theory, the technology should be applicable to any polar compound in any nonmetallic medium. The flexible design permits easy access for in situ treatment of organics and pesticides under buildings or fuel storage tanks.
STATUS:
The KAI RFH technique was accepted into the SITE Demonstration Program in summer 1992. The technique was demonstrated between January and July 1994 at Kelly Air Force Base, Texas, as part of a joint project with the U.S. Air Force Armstrong Laboratory. Brown and Root Environmental was the prime contractor evaluating and implementing RFH for the U.S. Air Force. A field demonstration of the IIT Research Institute RFH technology was completed in summer 1993 at the same site for comparison. The Demonstration Bulletin (EPA/540/MR-94/528) and the Technology Capsule (EPA/540/R-94/528a) are available from EPA. For further information on the IIT Research Institute technology, see the profile in the Demonstration Program section (completed projects).
DEMONSTRATION RESULTS:
For this demonstration, the original treatment zone was 10 feet wide, 15 feet long, and 20 feet deep. This treatment zone was based on RFH, operation at 13.56 megahertz (MHz); however, RFH was applied at 27.12 MHz to the top 10 feet of the original treatment zone to reduce the time on-site by half. Demonstration results were as follows:
· Uniform heating within the revised heating zone: significant regions had soil temperatures in excess of 100 °C with soil temperatures within a 3-foot radius of the antenna exceeding 120 °C.
· Significant amounts of liquid were heated to around 240 °C as strongly suggested by a measurement of 233.9 °C on the outside wall of the heating well liner.
· Soil permeability increased by a factor of 20 within the revised treatment zone.
· In the original treatment zone, the mean removal for TRPH was 30 percent at the 90 percent confidence level. Concen-trations in the pretreatment samples varied from less than 169 to 105,000 ppm; posttreatment concentrations varied from less than 33 to 69,200 ppm.
· In the revised treatment zone, the mean removal for total recoverable petroleum hydrocarbons (TRPH) was 49 percent at the 95 percent confidence level. Con-centrations in the pretreatment samples varied from less than 169 to 6,910 parts per million (ppm); posttreatment concen-trations varied from less than 33 to 4,510 ppm.
· Benzo(o)fluoranthene, benzo(a)pyrene, and bis(2-ethylhexyl)phthalate exhibited statistically significant removals within the original treatment zone. Benzo(o)-fluoranthene, benzo(a)pyrene, chrysene, pyrene, and fluoranthene exhibited statistically significant removals within the revised treatment zone.
· Contaminants may have migrated into and out of the revised treatment zone due to the design and operation of the SVE system.
· Cleanup costs are estimated to range from less than $100 per ton for large scale to between $150 to $250 per ton for small scale (hot spot) treatments.
FOR FURTHER INFORMATION:
EPA PROJECT MANAGER:
Laurel Staley
U.S. EPA
National Risk Management Research
Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7863
Fax: 513-569-7620
TECHNOLOGY DEVELOPER CONTACTS:
Raymond Kasevich
KAI Technologies, Inc.
170 West Road, Suite 4
Portsmouth, NH 03801
603-431-2266
Fax: 603-431-4920
Major Mark Smith
U.S. Air Force Armstrong Laboratory
Site Remediation Division, AL/EQW
139 Barnes Drive, Suite 2
Tyndall AFB, FL 32403-5323
904-283-6244
Fax: 904-283-6286
Clifton Blanchard
Brown and Root Environmental
800 Oak Ridge Turnpike
Jackson Plaza, A-600
Oak Ridge, TN 37830
615-483-9900
Fax: 615-483-2014