Catalytic oxidation of groundwater stripping emissions

Air stripping has been shown to be an efficient and cost effective method of removing volatile organic contaminants from groundwater and soil. The removal of dissolved fuel fractions and chlorinated solvents at efficiencies in excess of 95% has been demonstrated on several occasions. Unfortunately, these contaminants are transferred to the air where they may continue to pose an environmental and health threat. Regulation of such emissions has already been considered in many states including Michigan and California. However, few options are available for their control. Vapor phase carbon adsorption and thermal incineration are the two treatment methods which have been applied most often. These technologies have some disadvantages. Adsorption merely transfers the contaminant to a solid phase, which in turn requires disposal or regeneration. Thermal incineration may be expensive, since it requires a substantial energy input to destroy dilute gas phase contaminants. A new alternative is appearing in the form of catalytic oxidation. Like thermal incineration, it is an ultimate disposal method, but since it operates at much lower temperatures, the energy costs are also lower. This paper reviews the applicability of catalytic oxidation to control groundwater air stripping gaseous effluents with special attention given to system designs and case histories. The variety of contaminants and catalyst poisons encountered in stripping operations are also reviewed.