Life cycle assessment of sewage sludge treatment: Comparison of pyrolysis with traditional methods in two Swedish municipalities

• Published in: Journal of cleaner production 2024-05, Vol.455, p.142375, Article 142375
• Main Authors: Hosseinian, Aida, Brancoli, Pedro, Vali, Naeimeh, Ylä-Mella, Jenni, Pettersson, Anita, Pongrácz, Eva
• Format: Article
• Language: English
• Subjects: Biochar; Circular economy; LCA; Nutrient recovery; Pyrolysis; Resource Recovery; Resursåtervinning
• ISSN: 0959-6526; 1879-1786; 1879-1786
• DOI: 10.1016/j.jclepro.2024.142375

To achieve a closed nutrient cycle and more sustainable food production, enhanced nutrient recycling in the agri-food system is a necessity. Pyrolysis is an emerging technology to recycle the nutrient content of sewage sludge. The produced biochar can be used to reduce the need for mineral fertilizers; in addition, pyrolysis can also handle potential pollutants such as microplastics and pathogens present in sewage sludge. In this research, a life cycle assessment (LCA) was carried out to determine the environmental impact of sewage sludge pyrolysis as an alternative to current practices of two different cases of sewage sludge treatment in two municipalities in Sweden. The results indicated that avoiding mineral fertilizer production by using biochar has a significant influence on the environmental benefits. Furthermore, it showed that an integrated system of anaerobic digestion followed by pyrolysis could perform as the most environmental-friendly option for sewage sludge treatment with a lower risk of transferring pollution to the soil. [Display omitted] •Life cycle assessment has been performed to compare the current practice of sewage sludge treatment with alternative of pyrolysis.•Midpoint impact assessments results have been combined with analysis of other factors such as contamination transfer risk to soil, carbon sequestration and legislative aspects.•Avoided mineral fertilizer production shows a significant contribution to the environmental benefit of treatment methods.•Results show that pyrolysis could be an environmental preferable treatment for sewage sludge.•Future research should focus on innovative solutions of sewage sludge treatment which satisfy environment and human health simultaneously.