Which Advanced Oxidation Process is Best? An Effective Method for Micropollutant Removal in Contaminated Groundwater

The treatment of groundwater and other waste streams contaminated with hard-to-degrade micro pollutants is one of the most challenging applications for state of the art water treatment systems. Increasing regulatory requirements for the reduction or elimination of these contaminants requires alternative treatment processes. The thresholds given by the authorities for these micro pollutants are often close to the limits of their detection. Especially in California (USA) these regulations have extended the capabilities of conventional treatment processes to their limits.The combination of different treatment processes, such as ozonation with UV-irradiation, or with the addition of hydrogen peroxide results in more powerful combination processes, called AOP (Advanced – Oxidation – Process). Such processes are able to reduce these micro pollutants efficiently and in accordance with the authority's regulations.Pilot trials were carried out to treat groundwater of an industrial site contaminated with1.4 dioxane and chlorinated compounds like tetrachlorethene (PCE) and trichlorethene (TCE). Different AOP's (ozone // UV ˜ hydrogen peroxide // ozone ˜ hydrogen peroxide // UV) were tested and compared in terms of reduction rate and cost aspects. In this case the combination of ozone and hydrogen peroxide gave the best results.