ABSTRACT
In this study, a field-scale photo-chemical remediation reactor is designed and constructed. The reactor is used for destruction of vapor-phase volatile organic compounds (VOC), particularly chlorinated hydrocarbons, based on ultra violet (UV) photo-chemical reactions. UV light, when emitted at an effective absorption frequency, will cleave a VOCs carbon-chlorine bond, initiating long-chain radical reactions, thus reducing harmful contaminants to harmless products. The reactor consists of a stainless steel tubular vessel with internal dimensions 31.9 cm in diameter and 1.05 m in length. Three stainless steel baffles are welded inside the reactor to create a well-mixed vapor phase and homogeneous UV contact time. Sixteen Suprasil glass sleeves (Heraeus, Inc.) with external dimensions of 25 mm in diameter and 1.1 m in length are inserted along the length of the reactor positioned in a geometrical pattern to provide maximum UV exposure. The Suprasil glass sleeves are attached and sealed to the stainless steel reactor using a “stuffing-box” compression fitting. An amalgam UV lamp (Heraeus, Inc. NIQ 200/110) 257is placed inside every Suprasil glass sleeve. The Suprasil glass sleeves provide barrier protection between the UV lamps and the vapor-phase contaminant, and at the same time allow transmission of UV light at the primary wavelengths of 185 and 254 nm to the interior of the reactor. This design allows easy alteration and maintenance of UV lamps. The reactor is designed to operate with a vapor-phase temperature range from ambient to up to 300 degrees Celsius. A gas heater is installed to increase the influent vapor phase temperature. The reactor is mounted on a mobile frame to allow transport to field sites. The technology can be effectively applied to gaseous or liquid waste streams containing chlorocarbons. The next phase of the study will be to examine the destruction efficiency of various VOCs. Contaminants of interest include tetrachloroethylene (PCE) and trichloroethylene (TCE).
