Pesqueira, Joana; Silva, Adrián M. T.; Pereira, Manuel F. R.

The Sustainable Development Goal nº 6 aims to “ensure availability and sustainable management of water and sanitation for all”. Urban wastewater treatment plants (UWWTPs) combine technologies to improve the quality of wastewaters before discharge to water bodies or reuse. However, conventional solutions are unable to remove some micropollutants (pharmaceuticals, UV filters, pesticides, among others). These are found in water bodies at concentrations up to µg L-1. Despite such low concentrations, they may have long-term toxicological effects and advanced technologies can be applied in UWWTPs for their removal. The sustainability of these treatment options must be assessed, the United Nations suggesting LCA as a scientific tool for the development of environmentally-sound solutions for wastewater treatment. In this context, a literature review on the LCA of advanced treatments for the removal of micropollutants from secondary urban wastewaters was performed (J. Clean. Prod. 261 (2020) 121078). These studies were found to be scarce, especially when based on membranes, and most do not consider micropollutants in the assessment and use lab-scale data or calculations from literature averages. Only one report considered heterogeneous photocatalysis. Ozonation, Fenton-based processes and activated carbon adsorption were the most assessed processes. One of the reasons why LCA is seldom applied to this type of studies is the lack of approved characterization factors for micropollutants. Energy and chemical production were the main responsible for most environmental impacts. Hence, it is crucial to find alternatives for the reagents and bet on cleaner energy sources. In this communication, the state-of-the-art is presented along with the LCA of different solar-based treatments: heterogeneous TiO2-photocatalysis (with and without H2O2) and the photo-Fenton process, TiO2 without H2O2 addition being the preferred option if the photocatalyst is reused at least 5 times.