Presentation Date: Feb 14, 2026
AGSA Abstract
Chemical disinfection is the cheapest and most common method used in wastewater treatment. However, the generation of disinfection byproducts and greenhouse gases (GHG) remains a huge challenge. Our preliminary data and nitrogen balance estimations show that massive, unaccounted N2O emissions are present in water resource recovery facilities (WRRF) by biological production of hydroxylamine (NH2OH) and subsequent oxidation to N2O during disinfection (chlorination). Furthermore, chlorine has significant side effects, is harmful to aquatic life, and when combined with organics in wastewater streams, can form trichloromethane, which is carcinogenic. We demonstrate that photocatalysis is a viable alternative for the chemical-free disinfection of wastewater while mitigating N2O generation. Photocatalytic water treatment has been an active area of research for decades, but has yet to be commercially viable. Mass transport limitations, poor light management, and high rates of recombination result in impractically low energy efficiency. Our photocatalyst consists of commercial titania nanoparticles (P25) immobilised on quartz fibres, resulting in a high surface area photocatalyst on a UV-transparent support. The high photocatalyst surface area to reactor volume ratio (940,000 m2/m3) is advantageous for overcoming mass-transfer limitations, and the UV-transparent support improves photon management. In this work, we achieved the degradation of NH2OH with an electrical energy per order (EEO) of 0.4 and reduced N2O generation by 86 %. As a basis for future efforts in process scale-up and optimisation, an investigation into the reaction mechanism of NH2OH decomposition was performed. Using in-situ ATR-IR spectroscopy, we observe the adsorption of NH2OH to P25 via H2O desorption and the appearance of the N—O stretch band. Subsequently, under UV irradiation, we noticed the return of H2O bands as well as deformation of the N—O stretch band, indicating hydroxylamine breakdown. We hypothesise that surface reactions on the surface of P25 drive the decomposition of hydroxylamine.
