An integrated modelling framework to assess cascade water reuse in urban areas

In the recent years water scarcity has been an increasing problem for many countries worldwide. For this reason, there is currently a strong focus on increasing reclaimed wastewater reuse, especially for agriculture purposes (Fernandes and Cunha Marques, 2023). Besides, the cost of energy from conventional resources is increasing, thus the energy sector is moving towards more distributed and efficient use of heat sources across urban areas. Typical applications are heat pumps using local groundwater reservoirs and subsequently discharging in the nearby surface water bodies/artificial channels (recipients). Furthermore, for a better quality of these recipients and for a better performance of wastewater treatment plants (WWTP), stormwater can be collected in separated sewers discharging only the urban runoff to the recipient. In this context, water is subjected to multiple uses, with potential cross-contaminations across different compartments, posing a risk for the environment. Hence, there is a strong need for tools capable of supporting stakeholders towards a wiser and safer use of water resources, to ensure long-term resilience, stability, sustainability and security of the society with regard to water use. An integrated model was developed to simulate the fate and associated risk of hazardous contaminants in a cascade water reuse system.