Removal of trichloroethylene from waste gases via the peroxone process

In dealing with chlorinated organic compounds in waste gases, traditional treatment techniques show some severe shortcomings. Thermal oxidation may lead to the formation of dioxins, active carbon adsorption does not degrade the pollutants and biotechnological treatment is difficult since microorganisms do not always possess efficient degradation pathways for these compounds. These drawbacks explain the growing interest of the waste gas treatment sector for Advanced Oxidation Processes (AOPs) which were initially developed as water treatment techniques. AOPs generate highly reactive hydroxyl radicals that efficiently oxidise organic pollutants. In the peroxone process, this is done by a combination of ozone and hydrogen peroxide. In this work, the peroxone process is applied in an oxidative scrubber for the removal of trichloroethylene (TCE). Rapid oxidation of absorbed TCE in the liquid phase enhances TCE absorption. Practically, a gas stream contaminated with TCE is mixed with an ozone loaded gas stream. The mixture is led through a bubble column that is fed with a buffered hydrogen peroxide solution. The effect of different process parameters (flow rates, buffer concentration, pH, hydrogen peroxide/ozone dosage ratio, TCE dosage) on TCE removal was investigated. Depending on the operating conditions, removal efficiencies up to 98% could be attained.