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 Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

In Europe, sewage sludge is mostly used in agriculture (49%) or incinerated (25%). Technologies for sludge management that can support the transformation of wastewater treatment plants (WWTPs) to water resource recovery facilities (WRRFs) are emerging. Sludge pyrolysis is one of them. It can generate two main high-value co-products: heat and biochar. Moreover, biochar can be transformed into activated carbon. The economic and environmental impacts of sludge pyrolysis and its comparison to the direct application of sludge in agriculture and incineration are unknown. Therefore, we applied a life cycle assessment (LCA) and a cost-benefit analysis (CBA) of sludge pyrolysis. We quantified environmental externalities in an LCA and then applied the benefit transfer method to monetize these externalities, which were included in an economic CBA. Pyrolysis reduced impacts in five to nine LCA categories and had a positive economic net present value (NPV) compared to using sludge in agriculture. Pyrolysis with biochar production was not better than incineration, showing increased impacts in nine categories and negative NPVs (−19 to −22 €/t sludge). The factor driving differences between the alternatives was the assumed CO 2 externality price (164 €/ton CO 2 -eq) and the removal rate of pharmaceutical micropollutants of the sludge-based activated carbon. High uncertainty in environmental prices is one of the limitations of our study.

No abstract