Sand supported TiO2 photocatalyst in a tray photo-reactor for the removal of emerging contaminants in wastewater

There have been rising concerns about micro-pollutants that are not efficiently removed by conventional wastewater treatment plants. TiO2 photocatalysis is one of the most promising methods for their removal. One of the major challenges to the widespread application of TiO2 photocatalytic treatment is the use of fine TiO2 particles in suspension. A tray photocatalytic reactor based on using supported TiO2 as a photocatalyst was designed and constructed. The reactor maintains a thin water film over TiO2 supported on sand grains. Reactor performance for the degradation of phenol as a model compound was evaluated using 3 different approaches: (1) direct immobilization using the sol gel technique, (2) coating with TiO2/cement grout; and (3) binding with TiO2-epoxy coating. The recirculating tray configuration achieved photocatalyst activation, turbulent flow, avoiding treatment dead zones, and continuous water oxygenation. The reactor performance using the epoxy TiO2 sand composite was satisfactory in terms of degradation efficiency. The water turbidity remained unchanged indicating photocatalyst resistance to abrasion. Successful operation of the tray photo-reactor in the continuous mode was also achieved. The tray reactor is suitable for scale-up and commercialization due to five distinctive features which are: modular design; integrated storage; ease of continuous mode operation; absence of need for UV transmitting components; robustness and low cost of the epoxy-TiO2-sand composite.