Work

Comparative environmental assessment of integrated anaerobic digestion and pyrolysis systems for sewage sludge treatment: impact assessment using ReCiPe and USEtox methods

Year: 2025

Type: article

Abstract: Growing concerns over pollutants in sewage sludge have increased interest in integrating anaerobic digestion (AD) and pyrolysis (Py) to enhance energy recovery, reduce toxic compounds, and minimize environmental impacts. This study evaluates six treatment scenarios: standalone AD or Py, and four integrated AD-Py configurations, with or without aqueous pyrolysis liquid (APL) recycling. Environmental impacts were assessed using ReCiPe 2016 and USEtox® methods. Scenario S4:AD-Py-AD, which recycles APL to AD, achieved the highest climate change mitigation but also showed elevated freshwater ecotoxicity due to persistent organic pollutants’ emissions. Scenario S3:AD-Py, without APL recycling, demonstrated the best overall environmental performance, with low climate impact and ecotoxicity. In contrast, S6:ADCo-Py-AD, which includes a high-rate AD reactor and APL recycling, had the poorest performance due to high ecotoxicity. These findings highlight that the pyrolysis of digestate can be a beneficial pathway for sewage sludge treatment, showing the best environmental benefits compared to stand-alone processes.

Source: Bioresource Technology

DOI: 10.1016/j.biortech.2025.133431

Authors: Thea Lucia Indrebø, Gudny Øyre Flatabø, Ketil Stoknes, Gamunu Samarakoon Arachchige

Institutions: University of South-Eastern Norway, Lindum (Norway)

Language: English

Topic: Anaerobic Digestion and Biogas Production

Subfield: Building and Construction

Field: Engineering

Domain: Physical Sciences

SDGs: Responsible consumption and production, Clean water and sanitation, Climate action

Open Access status: hybrid

Estimated APC paid: $4,880