LCA of biochar filters – removal of pharmaceutical residues in wastewater

Sammanfattning

Pharmaceutical residues in wastewater have become an increasing environmental concern due to their potential impacts on aquatic ecosystems and human health. In response, the revised EU Urban Wastewater Treatment Directive introduces new requirements for quaternary treatment at wastewater treatment plants. Biochar filters have shown promising removal efficiencies for pharmaceutical residues, but their environmental performance from a life cycle perspective remains relatively unexplored. This study aimed to assess the climate change and toxicity impacts of biochar filters for quaternary wastewater treatment using life cycle assessment (LCA). Biochar produced from forest biomass and sewage sludge were compared in different scenarios including energy source and end of life treatment. A cradle to grave LCA was conducted which included feedstock production, transportation, pyrolysis, filter usage, and end of life treatment. The results showed that forest biomass was associated with lower environmental impacts than sewage sludge across all impact categories. The energy source strongly influenced climate change impacts, while feedstock selection was the dominant factor for toxicity related impacts. The forest biomass and sewage sludge biochar were characterized by different environmental hotspots associating with reference use and ash treatment respectively. The filter reduced the toxicity associated with measured pharmaceutical residues in treated wastewater by more than 90%. The study highlights the importance of applying a life cycle perspective when evaluating quaternary wastewater treatment technologies, as reductions in pharmaceutical emissions may be associated with environmental impacts elsewhere in the system.