Enhanced activated carbon production from lignin waste for treatment of As(V) and Cd(II) in wastewater: Sustainability and technological insights by prospective life cycle assessment

This study assessed the environmental impacts of producing activated carbon from technical lignin (TL-AC) for the removal of As(V) and Cd(II) from water, at the laboratory scale, and provided insights for future upscaling. An attributional LCA was initially conducted for seven laboratory-scale experimental setups, varying the temperature and the KOH:TL ratio. After identifying the best-performing scenario, three prospective (TL-2S-AC-3, TL-1S-AC-3, TL-1S-AC) and one baseline (Coal-1S-AC) scenarios were evaluated using a prospective life cycle assessment ( p LCA). A global prospection identified favorable locations for upscaling the technology, and an emission intensity indicator was proposed to improve sustainability comparisons across adsorbent materials. The results indicated that KOH use and energy consumption were key contributors to the global warming potential (GWP). TL-AC-3 achieved the best sustainability among the laboratory scenarios, with the lowest emission intensity per mass of As(V) (1.5×10 −4 kg CO 2 -eq mgAs −1 ) and Cd(II) (3.4×10 −4 kg CO 2 -eq mgCd −1 ) removed, demonstrating environmental advantages over commercial and other materials. In prospective assessments, the TL-1S-AC-3 scenario, featuring a simplified one-step pretreatment, showed potential GWP reductions of up to 60% (6.6 kg CO 2 -eq FU −1 ), compared to the laboratory-scale results. Brazil emerged as a favorable location for industrial deployment, due to its renewable energy matrix, with GWP values below 10 kg CO 2 -eq FU −1 across all prospective scenarios. These results highlighted TL-AC as an effective, lower-impact solution for arsenic and cadmium removal, with scalability potential in resource-abundant regions. • LCA and p LCA were conducted for an activated carbon from technical lignin. • Optimized scenario showed a Global Warming Potential (GWP) of 11.9 kg CO 2 -eq FU −1 . • Optimized scenario showed lower emission intensity than materials in the literature. • Reducing unit operations during pretreatment could decrease GWP by 60%. • Activated carbon from technical lignin has greater sustainability potential if developed in Brazil.