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The CHA Corporation has completed a US Air Force Phase II Small Business Innovation Research program to investigate the feasibility of using a novel microwave-based process for the removal and destruction of volatile organic compounds (VOCs) in effluents from non-combustion sources such as paint booth ventilation streams. Removal of solvents by adsorption followed by regeneration of saturated granular activated carbon (GAO) by microwave energy was accomplished in a single, fixed-bed reactor. Microwave regeneration of the saturated carbon in the fixed bed restored the original adsorption capacity of the GAO. During microwave regeneration the concentrated desorbed paint solvent was easily oxidized by passing the mixture of vapors through a fixed bed of an oxidation catalyst mixed with silicon carbide. After completing the fixed-bed pilot testing we assembled a pilot-scale continuous system and tested it during a three-month, continuous demonstration at McZClellan Air Force Base from 15 January to 16 April 1999. For this demonstration a 1OO-cfm stream of extracted soil vapors was continuously passed through the pilot system, and the airborne VOCs were removed. The success of this demonstration and piot-scale testing at CHA Corporation show the technical feasibility of using this system at an Air Force spray painting operation to continuously clean ventilation air. Laboratory and prototype test results were discussed., Presented at the 93rd Annual Conference Air and Waste Management Association at Salt Lake City, Utah.

The CHA Corporation has completed an U.S. Air Force Phase II Small Business Innovation Research program to investigate the feasibility of using a novel microwave-based filter device to remove and destroy unwanted by-products of combustion in exhaust gases. A Corning ceramic monolith soot filter that has about 90% soot removal efficiency was placed in a housing that allowed for microwave regeneration. Two filters were installed in parallel into the exhaust piping of a diesel engine. After 4-hour periods of operation, the filters were successfully regenerated with microwave energy for over 50 cycles. A prototype device for the destruction of NOx in exhaust gas generated by a 58- hp diesel engine was constructed and tested. The NOx control device comprised two separate fixed-bed reactors filled with catalyst beads. In the first, a Pt/Pd catalyst was used to convert NO into NO2 in the diesel exhaust. A reducing agent (JP-8) and microwaves were supplied to the second reactor, containing alumina-SiC pellets coated with a Pt/Rh/Pd catalyst, to destroy NO2. Because NO oxidation efficiency (45-55%) is suppressed by the high concentration of water in diesel engine exhaust, NOx destruction efficiencies were 30-40%, 10-20% lower than the NOx destruction obtained from smaller reactors. Test results obtained for this prototype microwave device clearly identified technical and economic advantages as well as technical difficulties of applying microwave-based filter devices to control pollutants in diesel exhaust. Preliminary experimental data indicate that the microwave reactor system developed for NOx destruction can be used to destroy waste rocket fuels including hydrazine and unsymmetric dimethylhydrazine in nitrogen or air streams. Laboratory and prototype test results will be presented.