Performance assessment of water reuse strategies using integrated framework of urban water metabolism and water-energy-pollution nexus

This paper evaluates the metabolism-based performance of a number of centralised and decentralised water reuse strategies and their impact on integrated urban water systems (UWS) based on the nexus of water-energy-pollution. The performance assessment is based on a comprehensive and quantitative framework of urban water metabolism developed for integrated UWS over a long-term planning horizon. UWS performance is quantified based on the tracking down of mass balance flows/fluxes of water, energy, materials, costs, pollutants, and other environmental impacts using the WaterMet2 tool. The assessment framework is defined as a set of key performance indicators (KPIs) within the context of the water-energy-pollution nexus. The strategies comprise six decentralised water reuse configurations (greywater or domestic wastewater) and three centralised ones, all within three proportions of adoption by domestic users (i.e. 20, 50, and 100%). This methodology was demonstrated in the real-world case study of San Francisco del Rincon and Purisima del Rincon cities in Mexico. The results indicate that decentralised water reuse strategies using domestic wastewater can provide the best performance in the UWS with respect to water conservation, green house gas (GHG) emissions, and eutrophication indicators, while energy saving is almost negligible. On the other hand, centralised strategies can achieve the best performance for energy saving among the water reuse strategies. The results also show metabolism performance assessment in a complex system such as integrated UWS can reveal the magnitude of the interactions between the nexus elements (i.e. water, energy, and pollution). In addition, it can also reveal any unexpected influences of these elements that might exist between the UWS components and overall system

Water-Energy-Pollutant Nexus Assessment of Water Reuse Strategies in Urban Water Systems using Metabolism Based Approach

This study analyses the water-energy-pollutant nexus performance of urban water reuse strategies by using urban water metabolism for a long-term planning period. A nexus assessment framework is developed for an Urban Water System (UWS) based on the WaterMet2 tool to track down water, energy and eutrophication flows over the main components of the UWS. A set of key performance indicators is then selected to represent the water-energy-pollutants nexus. The suggested method is demonstrated in a real case study in Mexico for eight hypothetical reuse strategies including six greywater (GW) recycling options (decentralised) and two reclaimed water distribution (centralised) that are compared with Business As Usual (BAU) strategy ('do nothing') in the UWS. The intervention options are set up at either 10% or 50% of adoption rates (proportional to household and demands within the UWS) to be implemented at years 10 and 20. The results show that greywater strategies consume more energy than the BAU if aerated technologies are implemented but the same strategies can reduce eutrophication due to reduction of untreated discharge of pollutions into receiving water bodies and potable water saving. Combining low-energy GW options with high adoption rates results in highly efficient performance with respect to nexus approach. The proposed metabolic-nexus based approach is able to provide useful information about the performance and environmental impacts of centralised and decentralised water reuse options to support management decisions