The effects that climate change could have on the future availability and quality of fresh water are growing concern for experts and the society as a whole. Thus, it is increasingly necessary to assess in an objective and rigorous way the environmental impacts of different infrastructures for wastewater management and treatment, such as sewers and wastewater treatment plants (WWTPs).
Life Cycle Assessment (LCA) is a very powerful tool to identify and quantify the different environmental impacts of a product or process: greenhouse effect, water and soil toxicity, ozone layer depletion… Unlike other methodologies, LCA considers all the stages of the product from “cradle to grave” (i.e., from raw material extraction through materials processing, manufacture, distribution, use, repair and maintenance, to disposal or recycling). Therefore, for urban wastewater treatment LCA can be used to assess the environmental impacts of the manufacture and construction of sewers and WWTPs, their operation and the dismantling. Another tool to assess environmental impacts that has gained special relevance in the past few years is water footprint. Based on the principles of life cycle assessment, water footprint measures the amount of different water fluxes used to produce a good or service, and assesses their environmental impacts.
The doctoral thesis entitled “Comprehensive inventories for Life Cycle Assessment in urban wastewater systems” by Sadurní Morera i Carbonell is a significant step forward for a better development of the life cycle assessment methodology and its application to urban water cycle. The thesis was carried out at UdG LEQUIA research group and was directed by Drs Joaquim Comas (LEQUIA-UdG, ICRA), Lluís Corominas (ICRA) and Miquel Rigola (LEQUIA-UdG). To achieve his goals, Sadurní Morera used data from wastewater treatment plants of six Catalan municipalities (Girona, Navàs, Balaguer, Manlleu, l’Escala and La Garriga-Granollers), with two different management strategies. Not only are the outcomes relevant from the methodological point of view, but also regarding the resulting assessment of the 6 WWTPs taken into account.
Thus, the researcher has developed a new procedure to treat inventory data for the construction of WWTPs in a reliable, consistent and, at the same time, fast and versatile way. Among its functionalities, we find the possibility of carrying out modular analysis of each of the subprocesses of the construction, maintenance and operation stages; a semi-automatic tool to assess sewers construction; and regressions that correlate materials and energy depending on the size of the plant, valid for WWPTs of 1.500 – 21.000 m3/h capacity. Concerning the environmental impact assessment of the 6 WWTPs, the relevance of sewers renovation and WWTP civil work and equipment – two elements which had been discarded in other studies – was interestingly high. The thesis also applies the water footprint assessment methodology to the operation stage of one WWTP (La Garriga). Nevertheless, one of its most valuable outcomes of the thesis is perhaps the flexible and innovative application of LCA to urban wastewater treatment, which could revert to a wider acceptance of the methodology among decision makers (practitioners, managers, politicians…).