Photoelectrocatalytic disinfection of water

Abstract

The development of new technologies that can treat water at the household level are essential to help achieve the United Nations sustainable development goal 6 ‘Water for All’ by 2030. This research focused on the development of a photoelectrocatalytic (PEC) system to disinfect water using solar irradiation.

A PEC cell with a TiO2 nanotube photoanode was tested under solar simulated irradiation. The initial work displayed a 5-log reduction of E. coli in 30 min. experiments using stream water showed a 3.7 log reduction in 3 h and a 28% reduction in total organic carbon. Only irradiation displayed 1.1 log reduction and 7.5% reduction in TOC.

Subsequently, a CPC reactor with TiO2 nanotube photoanode and a carbon felt counter electrode was tested in South Africa under real sun for the disinfection of harvested rainwater. The PEC had a 6.2 log reduction of E.coli (2.8 log photo-inactivation) and P.aeruginosa had a 5.4 log reduction (1.4 log photo-inactivation). The viability was examined using EMA-qPCR, with the PEC having superior results. The current correlated to the UV intensity, which could be used to calculate the UV intensity and potentially provide some feedback control for the system.

Analysis of the electrodes, electrolyte, UV intensity and the surface-to-volume ratio was examined. The generation of H2O2 at the cathode played an important role in the overall rate of inactivation. At the photoanode, hydroxyl radical and superoxide radical anion was detected. A high surface-to-volume ratio reactor concluded that the minimal distance between the electrodes overcomes the adverse effects of low conductivity and the presence of dissolved organic matter, resulting in a 5.0 log reduction of E. coli in 20 min.

This research demonstrates that PEC is a potential household treatment option for the disinfection of water. More work is needed to improve solar efficiency and for testing under real conditions.

Date of Award	Sept 2021
Original language	English
Sponsors	Department for the Economy & Royal Society - Newton Mobility Grants
Supervisor	John Byrne (Supervisor) & Pilar Fernandez-Ibanez (Supervisor)