Evaluation of Photocatalysis for Gas-phase Air Cleaning Part 2: Economics and Utilization

Several approaches to estimate the cost of installing and operating a photocatalytic oxidation (PCO) device for application in various treatment concerns are presented. First, a simplified approach for estimating the cost of a PCO device using laboratory data is presented in some detail. Second, the cost of ownership of a PCO device for treating out gases from soils contaminated with liquid solvents is compared with other treatment technologies, including granular activated carbon (GAC) and groundwater extraction with liquid phase UV/peroxidation. Third, a study based on a consortium of semi-conductor companies demonstrated that the cost of ownership of PCO for point-of-use (POU) applications is not likely to cost less on a "per CFM basis" than existing end-of-pipe (EOP) technologies. However, the study findings indicated that in a number of specific cases, PCO may provide a cost-effective alternative to EOP technologies. Last, a report was published comparing the first and operating costs of PCO vs. GAC. The study reported that (1) due to the high first and operating costs of a PCO device compared with the GAC approach, PCO is not likely to replace GAC as a technology for treating a steady-state inlet feed of VOCs: and (2) PCO can improve in this comparison (to GAC) if improved catalysts capable of high reaction rates and quantum yields are developed and if lower cost, low-pressure mercury-vapor lamps can be employed as a substitute for the medium-pressure lamps.