Life Cycle Environmental Impacts of Sewage Sludge Pyrolysis and Their Dynamic Evolution

Abstract

Thermal methods, especially pyrolysis with biochar production, are emerging as potential solutions for sewage sludge treatment. Life cycle assessment (LCA) is commonly used to evaluate environmental impacts, and the promising performance of pyrolysis has been demonstrated in previous LCA studies. This study goes into further detail in impact analysis by applying prospective and dynamic LCA while incorporating multiple approaches to consider biogenic carbon emissions. The results show that the system provides climate benefits over a 100 year period, with findings remaining robust despite variability in facility parameters and uncertainties in model assumptions. The prospective LCA results indicate that the climate balance of the system is expected to improve over the years. The dynamic analysis demonstrates that the system provides significant temporal carbon capture, which gradually decreases as biochar decomposes in soil. Taking two perspectives on biogenic carbon accounting reveals how the results can be affected by methodological decisions. This study offers a more detailed view of the dynamic evolution of climate impacts across the facility’s entire operational lifetime.