ENERGY AND ENVIRONMENTAL RESEARCH CORPORATION

(Reactor Filter System)

TECHNOLOGY DESCRIPTION:

The Energy and Environmental Research Corporation (EER) Reactor Filter System (RFS) technology is designed to control gaseous and entrained particulate matter emissions from the primary thermal treatment of sludges, soils, and sediments. Most Superfund sites are contaminated with toxic organic chemicals and metals. Currently available thermal treatment systems for detoxifying these materials release products of incomplete combustion (PIC) and volatile toxic metals. Also, the large air pollution control devices (APCD) often required to control PICs and metals are generally not suitable for transport to remote Superfund sites. EER designed the RFS to avoid some of these logistical problems. The RFS uses a fabric filter installed immediately downstream of the thermal treatment process to control toxic metals, particulates, and unburned organic species. The RFS involves the following three steps:

• First, solids are thermally treated with a primary thermal process, such as a rotary kiln, fluidized bed, or other system designed for thermal treatment.
• Next, a low-cost, aluminosilicate sorbent, such as kaolinite, is injected into the flue gases at temperatures near 1,300 C (2,370 F). The sorbent reacts with volatile metal species such as lead, cadmium, and arsenic in the gas stream and chemically adsorbs onto the surfaces of the sorbent particles. This adsorbtion forms insoluble, nonleachable alumino-silicate complexes similar to cementitious species.
• Finally, high-temperature fabric filtration, operating at temperatures up to 1,000 C (1,830 F), provides additional residence time for the sorbent/metal reaction to produce nonleachable by-products. This step also provides additional time for destruction of organic compounds associated with particulate matter, reducing ash toxicity. Because of the established link between PIC formation and gas-particle chemistry, this process can virtually eliminate potential polychlorinated dioxin formation.

The RFS may improve the performance of existing thermal treatment systems for Superfund wastes containing metals and organics. During incineration, hazardous organics are often attached to the particulate matter that escapes burning in the primary zone. The RFS provides sufficient residence time at sufficiently high temperatures to destroy such organics. Also, by increasing gas-solid contact parameters, the system can decrease metal emissions by preventing the release of metals as vapors or retained on entrained particles.

The figure shows the RFS installed immediately downstream of the primary thermal treatment zone at EER's Spouted Bed Combustion Facility. Because the spouted bed generates a highly particulate-laden gas stream, a high-temperature cyclone is used to remove coarse particulate matter upstream of the RFS. Sorbent is injected into the flue gas upstream of the high temperature fabric filter. A conventional baghouse is available for comparison with RFS performance during the demonstration. However, the baghouse is not needed in typical RFS applications since the high-temperature filtration medium has shown similar performance to conventional fabric filtration media.

WASTE APPLICABILITY:

The RFS is designed to remove entrained particulates, volatile toxic metals, and condensed-phase organics present in high-temperature (800 to 1,000 C) gas streams generated from the thermal treatment of contaminated soils, sludges, and sediments. Many conventional treatments can be combined with the RFS technology. Process residuals will consist of nonleachable particulates that are essentially free of organic compounds, thus reducing toxicity, handling risks, and landfill disposal.

STATUS:

The RFS was accepted into the Emerging Technology Program in 1993. EER developed the pilot-scale process through a series of bench-scale screening studies, which were completed in September 1994. These screening studies guided the sorbent selection and operating conditions for the pilot-scale demonstration. The tests were completed in 1996; the final report will be available from the National Technical Information Service.

FOR FURTHER INFORMATION:

EPA PROJECT MANAGER:
Steven Rock
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7149
Fax: 513-569-7105

TECHNOLOGY DEVELOPER CONTACT:
Neil Widmer
Energy and Environmental
Research Corporation
18 Mason Street
Irvine, CA 92718
714-859-8851
Fax: 714-859-3194