Advanced photocatalytic oxidation processes for micropollutant elimination from municipal and industrial water

Abstract

The objective of this study was to develop and validate an innovative technology to ensure efficient elimination of different types of micropollutants and toxic compounds in waste water. The process is a tertiary treatment process, which can be easily integrated into municipal and industrial waste water treatment plants. It is based on oxidation by ozone and subsequent photocatalytic treatment. After development and validation of this system at laboratory scale, the solution was tested at pilot scale. The first part of this work was to develop a TiO₂-based film on glass substrate, characterize its physico-chemical properties and optimize its composition at laboratory scale to be photoactive on the degradation of model water containing several pollutants. The model water consisted of a mixture of 22 major micropollutants including pesticides, plasticizers, brominated compounds, and pharmaceuticals. The best photocatalyst for the degradation of the selected micropollutants was a TiO₂ coating doped with 2 wt% of Ag and where 10 wt% P25 was added. Then, in order to scale up the process, its deposition on steel substrates was tested with dip and spray coating at laboratory scale. Calcination parameters were optimized to limit steel corrosion while keeping similar photoactive properties regarding the degradation of the model polluted water. The optimized solution was deposited by spray coating in a pilot scale reactor in order to assess its efficiency in a pilot water treatment plant.

Keywords: Photocatalysis; Pilot reactor; Sol-gel process; TiO(2)-Based film; Waste water treatment.