Sustainable methods for the removal of bacteria and NOM from drinking water

Abstract

Climate change alters natural organic matter (NOM) and pathogen concentrations in surface waters, causing increasing strain on water treatment infrastructure. More effective NOM and pathogen removal from drinking water supplies is required to develop a robust and versatile water treatment process for the future. Photocatalysis has been regularly reported to have high efficacy for the removal of NOM, as well as pathogens, from water at laboratory scale. This Thesis aims to assess the practical limitations of photocatalytic water treatment with the goal of making it suitable for implementation at industrial scale.

Primarily this work uses recent advancements in UV-LED technologies and catalyst design and setup to explore how they have made photocatalytic disinfection and NOM treatment more viable for use in industrial water treatment, to alleviate the growing pressures presented on current infrastructure. Shorter wavelength LEDs, such as UVA-LEDs, with significantly higher energy efficiencies and highly tuned wavelength emissions compared to traditional alternatives, have only recently become commercially available, and are therefore sparsely investigated. In addition, this Thesis utilises seldom-used real surface water samples to bridge the gap between lab research and industry application, and modified catalysts, previously untested in their ability to remove NOM from water.

Results from this Thesis show how LED-driven photocatalysis, although not currently viable for use in industry, could prove invaluable as a sustainable water treatment technology as LED technologies continue to develop, provided that the recommendations for operating conditions outlined in this Thesis are considered. Investigations found that inclusion as a tertiary polishing step, given its capacity to remove NOM and pathogens before disinfection, could be effective at reducing threats to public health and drinking water infrastructure.