Siegfried Müller

Design and characterization of a multi-phase annular falling-film reactor for water treatment using advanced oxidation processes

In this work, a laboratory-scale of a 3-phase [(I) immobilized photocatalyst, (II) polluted water and (III) oxygen or ozone] falling-film reactor was designed and developed for heterogenous advanced oxidation processes. Characterization and assessment of the annular falling film reactor for handling different advanced oxidation methods was performed. Degussa P-25 TiO2 particles were immobilized on borosilicate glass (BSG) and polymethylmethacrylate (PMMA) tubes and used as a photocatalyst in this study. The characteristics of the falling film reactor, such as the thickness and distribution of falling films and the level of gas absorption into the liquid falling films, as well as the effect of UVA irradiation on the decomposition of ozone inside the falling film reactor, were studied. The adsorption of a model compound on the surface of the immobilized catalyst was measured and the photoactivity of the immobilized photocatalyst was evaluated for the degradation of the model compound. Oxalic acid was chosen as the model compound in this study.

Synergistic effect of the combination of immobilized TiO2, UVA and ozone on the decomposition of dichloroacetic acid

The performance of a heterogeneous photocatalytic ozonation system (TiO2/UVA/O3) was evaluated on the degradation and mineralization of dichloroacetic acid as a contaminant in aqueous solutions by means of a planar reactor. The commercial product “Pilkington ActiveTM glass” was used as the immobilized TiO2 photocatalyst and it was irradiated by near UV light in this study. The synergistic interaction between ozone and the photoactivated TiO2 surface was discussed and highlighted. Furthermore, the influences of initial concentration and temperature on the degradation rate of dichloroacetic acid and the ozone consumption level during the oxidation process were investigated. The concentrations of dichloroacetic acid and chloride anions produced during degradation were measured using ion chromatography. The mineralization of dichloroacetic acid was evaluated by Total Organic Carbon (TOC) measurements. The degradation of dichloroacetic acid by photocatalytic ozonation showed good agreement with the kinetics of first-order reactions with respect to dichloroacetic acid.

Decolorization of Wastewater Produced in a Pyrolysis Process by Ozone: Enhancing the Performance of Ozonation

This paper shows the results of color removal from a wastewater produced in a plastic pyrolysis process by ozonation. The influence of parameters such as temperature, reactor geometry, UVA, ozone input, and finally spraying of wastewater on performance enhancement of the decolorization process will be discussed. Due to the long residence time of O3 molecules in the gaseous phase, recycling and spraying the wastewater in a pre-filled ozone chamber show a remarkable effect on decreasing the decolorization process time. At the end of this paper, an application of “micro-bubble producer” in this field, and its advantages will be introduced.