An Improved Flow-Through Photocatalysis Device for the Removal of Emerging Contaminants

Cost-effective procedures can't achieve complete removal of priority contaminants present in water at very low concentrations (as pesticides or pharmaceuticals). Advanced oxidation processes and photo-degradation are considered promising technologies for such tasks. However, while on one hand, hundreds of scientific publications based on such processes are published every month, on the other hand, only a few fully operational devices can be found in the water industry due to technical problems, making the implementation of the scientific achievements expensive or ineffective at a large scale. This study presents a device planned to overcome the difficulties exhibiting efficient light-catalyst-pollutant contact while enabling the combination of catalytic processes, including the separation of solid phase catalysts. The device is based on a flow-through chamber with a UVC lamp, pumps that dose the reactants (hydrogen peroxide solution, solid catalyst suspension) into the effluent as required, and a membrane filter that recirculates the solid catalysts. The device was tested for the removal of iohexol (with addition of low concentrations of hydrogen peroxide), and acesulfame (as photolysis only) at low concentration, and complete removal was achieved in a few minutes. The device was also successfully tested in raw and spiked wastewater treatment plant effluents. We concluded that such a system can be the skeleton of future, relatively cheap and effective AOP devices working at full industrial scale.