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

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.