Sammendrag
Decentralized wastewater treatment and reuse emerges as an alternative approach to conventional water management with the potential to alleviate escalating pressures on the water cycle and secure future supply. This study performs a complete environmental assessment of a building-scale system capable of recycling urban wastewater on-site and treating rainwater to drinking water quality.
Material flow analysis and life cycle assessment are performed with the aim to quantify the impacts of extreme decentralization in a European setting and compare the environmental profile of the system with that of traditional, centralized treatment. The impact assessment is performed in Brightway2 following the ReCiPe (H) v1.03 methodology and covers both the construction and operation of the technology. The comparison with the centralized approach considers all infrastructure involved in water management. Four site-specific implementation scenarios are modelled to evaluate the sensitivity of the results to regional parameters.
The results confirm the environmental benefits of implementing decentralized water reuse systems in terms of resource recovery and life cycle impacts. The assessed reuse layout can double the nutrient and energy recovery potential of conventional treatment and outperforms the centralized approach in 10/15 of the studied ReCiPe midpoint indicators. The operation of the system dominates impacts to all environmental indicators and is greatly influenced by the switch of regional factors (esp. national electricity mixes), which contrastingly have a limited influence on the construction phase. The inclusion of rainwater capture and treatment equipment yields positive results in all studied locations. However, it must be accompanied by site-specific assessments as insufficient rainfall can cause avoided impacts from water recycling to be lower than those caused by installation of the necessary equipment.