The Life Cycle Assessment of Methane Production with anaerobic digestion integrated with pyrolysis techniques for Sludge waste minimization

Abstract

Anaerobic digestion (AD) is an effective method widely used for treating organic waste and converting treated waste into biogas, a renewable energy source. Recently, there has been a focus on combining anaerobic digestion with pyrolysis because of its possibility to increase biogas yield and better utilization of wastes. The main purpose of this research was to compare two potential biogas production systems fed with municipal sludge in terms of the effects they had on the environment. The anaerobic digestion of municipal waste sludge is depicted in the two following scenarios: Scenario 1 is focused on a simple anaerobic digestion process whereas Scenario 2 involves a combination of anaerobic digestion with pyrolysis. The objective of the study was to understand and evaluate the following scenarios that would lead to the least environmental impacts throughout the production lifecycle. An LCIA method can be used in order to systematically compare the environmental profile of both scenarios within a cradle-to-gate concept. When comparing the two scenarios, the analysis proved that Scenario 2, which introduced pyrolysis, had higher immediate environmental impacts which resulted from a more complicated process and energy needs. This analysis demonstrates that the selection of process efficiency and sustainability objectives is crucial and that additional progress in energy efficiency or emissions reduction may enable Scenario 2 to be an energy-efficient and environmentally superior method of biogas generation. The potential long-term benefits of integrating pyrolysis, such as reduced waste and valuable byproducts, suggest that Scenario 2 could become a more sustainable approach to biogas production with improvements in energy efficiency and emissions control.