Carbon footprints of incineration, pyrolysis, and gasification for sewage sludge treatment

• Published in: Resources, conservation and recycling conservation and recycling, 2025-01, Vol.212, p.107939, Article 107939
• Main Authors: Chang, Huimin, Yuan, Jiayi, Zhao, Yan, Bisinella, Valentina, Damgaard, Anders, Christensen, Thomas H.
• Format: Article
• Language: English
• Subjects: Global sensitivity analysis; Life cycle assessment; Sewage sludge; Thermal technologies; Uncertainty analysis
• ISSN: 0921-3449
• DOI: 10.1016/j.resconrec.2024.107939

•Pyrolysis and gasification technical configurations shifted GWP from loads to savings with greener energy system exchange.•Lower temperature pyrolysis and gasification with char as AC has over 70 % probability to get lower GWP than incineration.•Climate change impact uncertainties in TCs were influenced by TS and VS contents in sewage sludge.•Optimizing processes like thermal drying and syngas production is critical for stable technology evaluations.•Higher TS and VS contents in sludge reduce climate impacts due to lower energy demands and better energy recovery. Thermal technologies have gained increasing attention in sludge management. This study applied life cycle assessment to assess the impacts to climate change of ten technological configurations (TCs) treating sludge with incineration, gasification, and pyrolysis. We used distributions of process parameters for quantifying the associated uncertainties and considered different energy exchanges. In a 55 %-fossil energy system, the TCs with various thermal processes showed impacts to climate change in a wide range of −2000 to 2000 kg CO2 eq/t total solid. A probabilistic comparison indicated that with a 10 %-fossil energy system, TCs with gasification and pyrolysis showed a > 95 % probability of performing better than TCs with incineration. Energy consumption and dewatering parameters contributed significantly to the uncertainty due to their large variation and sensitivity. This study emphasized the potential of optimizing key parameters and provided evidence from a climate change perspective for better technological selection and development in sludge management. [Display omitted]