Opportunities for Water Reuse Implementation in Metropolitan Areas in a Complex Approach with an LCA Analysis, Taking Warsaw, Poland as an Example

Abstract

Water shortages are currently becoming a more global than local issue. This paper aims to demonstrate a complex, universal urban water reuse system, allowing for a reduction of freshwater withdrawal. Opportunities for improvement were analyzed in the categories of municipal services: power and heat production, greenery irrigation, landscaping, street and public transport fleet cleaning. Technical possibilities were coupled with current international legislative requirements. Two scenarios for universal, complex water reuse systems in the municipal area were evaluated, including all essential city services. Results of the case study show that ozonation and filtration of treated wastewater should be sufficient to obtain the desired water quality for urban purposes. Current legislation mainly addresses agricultural water reuse, so their requirements should be adjusted to assess the water quality needed for other applications. When water is used in public spaces, constant monitoring for the presence of pathogens should be maintained due to the risk of human exposure. A life cycle assessment was conducted to evaluate the environmental impacts associated with the topic of water transportation in urban areas, which is infrequently considered in such studies. Two scenarios including different means of transport were compared. It was shown that with constant daily operation, it is necessary to build an independent water network, since the environmental impact of water delivery by tank lorries increases substantially.