The uncertainty analysis of life cycle assessment for water and wastewater systems: Review of literature

Abstract

Water and wastewater systems play an essential role in sustainable development and public human health, which have multiple environmental impacts that must be regarded. Life cycle assessment (LCA) is a promising and effective environmental evaluation framework to consider the potential impacts of WWSs and processes. Over the last two decades, there has been a significant increase in the literature on LCA of WWSs, still despite LCA s’ advantages, it has some limitation due to the intensive data needed for this analysis, which cause uncertainty in results. The reliability of LCA results is unavoidably affected by uncertainty, which can have unintended consequences on decision-making. Failure to account for uncertainty in LCA researches can decrease confidence in the outcomes. Thus, it is essential to consider the different types of LCA uncertainty to obtain valid results for appropriate decision-making. Despite the significance of uncertainty, no review paper has yet focused on considering uncertainty in LCA research for water and wastewater systems. Therefore, this study aims to provide an overview of the uncertainty in LCA for water and wastewater systems. This review includes a detailed and in-depth review of different types of considered uncertainty and detected research gaps, and proposes ideas for future researches. The analysis indicates that 77 % of the papers only considered input data uncertainty and data variability using the Pedigree matrix. This is crucial given LCA's sensitivity to data, although it should be noted that the Pedigree matrix relies heavily on expert judgment and lacks a documented empirical foundation. As a result, the accuracy of results derived from this method may be less than ideal. In addition to input data uncertainty, both model and scenario uncertainty can have a considerable effect on LCA results accuracy. However, only 13 % of the papers included model uncertainty, and no studies focused on scenario uncertainty in water and wastewater systems research.