The continuous trend towards increasing urbanization brings to the fore the issue of urban sustainability. As part of urban systems, the urban water cycle should limit its environmental impact while providing sufficient drinking water supply and waste water treatment to growing cities.
The AQUAENVEC project (funded by the European Commission) aims to provide decision-making tools to optimize eco-efficiency in the urban water cycle, through environmental and economic life-cycle approach (LCA and LCC). The recently released ISO14045 on eco-efficiency is proposed as a new framework to address the integration of economic and environmental performance. The environmental and economic impact of the urban water cycle activities (water extraction, drinking water treatment, transport and distribution, sewer networks and waste water treatment) and their reduction potential are analysed in parallel and merged by relating the environmental assessment to the product system value assessment.
In a first step, the methodology is applied to two case studies: one in the Mediterranean area, on the east coast of Spain (Catalonia) and the other on the Atlantic coast (Galicia). Catalonia and Galicia have different climates: in the Mediterranean area, precipitation is scarce, with high seasonal and yearly variability, while Galicia receives more constant rain amounts throughout the year. The water stress in Catalonia is increased by a high population density, which reaches twice that of Galicia. Different characterisation factors are used for each region, which enables to analyse how disparities in water availability and water use patterns affect the sustainability of the urban water cycle.
The two main challenges in this first step are the implementation of correct regionalisation factors and the inclusion of water use as an impact category linked to resource depletion. In addition, water quality parameters of inlet and outlet water effluents in treatment plants should be included in order to account for the higher removal efficiency of more polluting technologies. In addition, further research on specific inventory data for the water sector is being carried out, especially for chemicals used in water, waste water and sludge treatment.
The second phase focuses on the development of an eco-efficiency assessment tool, applicable to any urban area, which enables decision-makers to obtain guidelines as to best-practices to improve eco-efficiency of the urban water cycle. Indicators promoting the sustainable use of natural resources and reuse of end-products will be integrated to the generic tool thus aiming to achieve a sustainable management of the urban water cycle.