Reducing inventory data requirements for scenario representation in comparative life cycle assessment (LCA), demonstrated on the urban wastewater system

Wastewater reuse has become an attractive option for alleviating the stress from water resources. Centralized wastewater reuse is a common and continuously expanding practice worldwide, but the advantages of centralized over decentralized approaches are lately being questioned. Life cycle assessment (LCA) is a well-accepted means of assessing the overall environmental performance of service systems, however, construction of a life cycle inventory (LCI) for complex systems such as urban wastewater systems, is very time consuming. Lack of resources and unavailability of data often enforce constraints on the scope of the assessment. In such cases it may be beneficial to consider the approach presented here, which manifests the differences between the studied alternatives. By eliminating processes that remain unchanged, less data and human resources are required in building the inventory, and less parameter uncertainty is introduced into the analysis. The proposed approach is demonstrated through the conceptual modeling steps of an assessment of decentralized urban wastewater reuse alternatives.