Assessing the environmental sustainability of decentralized photocatalytic treatment in healthcare facilities

Abstract

The rapid increase in pharmaceutical pollutants in aquatic ecosystems has driven the need for innovative wastewater treatment solutions. This study evaluates the environmental performance of a Fe₃O₄/ZnO nanocomposite-based photocatalytic reactor, applied as a tertiary treatment for hospital wastewater. Life cycle assessment was used to compare four operational scenarios of the photocatalytic reactor, varying oxidant concentration and light intensity. The results show that the reactor is able to achieve 80 % removal efficiency for a complex wastewater mixture of nine micropollutants, meeting the standards outlined in the European legislation. However, compliance with legislation for some highly recalcitrant pollutants (e.g., trimethoprim) may require an increase in equipment size and operation time, resulting in a higher climate change impact (4.94 kg CO2/m3) if compared to other compounds that could be used as reference (e.g., 0.37–3.02 kg CO2/m3 for diclofenac and 17α-ethynylestradiol, respectively). Since most of the environmental impact of technology comes from the use of electricity in the lamps (65 % of the impact profile), strategies should be developed to offset this high resource demand. Ideally, the solutions should result in an environmental trade-off for freshwater ecotoxicity with lower impacts than direct discharge (3.6 CTUe/m3). While the variability between scenarios is in the range of 1.07–10.94 CTUe/m3, the most preferable option resulted in impacts in ecotoxicity of 2.79 CTUe/m3 and greenhouse gas emissions of 1.20 kg CO2eq./m3. This scenario not only resulted in lower direct and indirect environmental impacts on aquatic ecosystems compared to the case where no treatment was applied, but it also nearly fulfilled legislative requirements and remained competitive with other existing technologies such as solar-powered photocatalysis, photo-Fenton, electro-Fenton, and adsorption.