Sustainability and Strategic Assessment of Water and Energy Integration Systems: Case Studies of the Process Industry in Portugal

The most recent sustainability policies of each region of the world conjointly define that economic activities shall follow the principles of natural resource use minimisation, as well as eco-efficiency and circular economy promotion, in addition to the specific objectives defined in each policy. Most recently, a group of researchers has proposed innovative conceptual systems designated Water and Energy Integration Systems (WEIS) for issues related to water and energy use (two prominent categories of natural resources). These are based on engineering projects encompassing a multitude of processes and technologies. In this work, an assessment based on the determination of several sustainability and strategic-aims-related indicators is performed for two WEIS case studies set in the Portuguese process industry (in this case, a ceramic plant). Such an assessment serves as an expansion of previously performed studies on the economic and environmental viability associated with the installation of this type of system with the ultimate goal of proving the effective compliance of water- and energy-use-reduction-related results with sustainability and strategic aims (namely, the ones associated with the most recent policies and aspects associated with the social, economic, and environmental pillars of sustainability). The results for the overall assessment proved that the conceptualised WEIS are robust in terms of eco-efficiency, circular economy potential, and strategic objective achievement potential (with a 6.46% and 4.00% improvement for the aggregated eco-efficiency indicator having been obtained for, respectively, case studies 1 and 2, a null water discharge for both case studies, and a level of 8.58% and 6.69% of recirculated heat over total energy consumption, respectively). The obtained results prove the sustainability promotion effectiveness of the WEIS as conceptual systems. The overall set of indicators defined in this work are part of a methodology that may be used and adapted for further studies considering the innovative WEIS approach, with the specific results obtained in this work presented with the aim of their being used for comparison.