Decomposition of detergents present in car-wash sewage by titania photo-assisted oxidation

Advanced oxidation process (AOP) has been shown to be effective in water and air decontamination. Ultraviolet-oxidation has been evaluated for most contaminants. In this work UV/TiO2/O-2 version of AOP method was used to decompose surfactants and, applied in car washing installations, commercial products. The influence of such parameters like the amount of TiO2 catalyst's dose, the acidity of aqueous solution and the type of applied UV lamp were examined. Additionally, in order to evaluate the effects associated with photocatalysis, studies of the contributions like adsorption of surfactants on catalysts and photooxidation were undertaken. Photocatalytic oxidation of Cleentex aqueous solution was investigated, using TiO2 and 10% - TiO2/SiO2 as catalysts The most efficient process appeared to occur in weakly basic solution pH = 8.9 with TiO2 catalyst dose about 1.5 g dm(-1). The photo-efficiency of UV lamps should be verified in order to avoid the excessive losses of light power. All detergents showed a high affinity for photocatalytic decomposition and final degree of COD reduction was in the range 35-60%, depending on detergent composition. The degree of TOC reduction was slightly lower.