Life cycle assessment of sewage sludge treatment and disposal technologies based on carbon emissions and environmental impacts

This study aimed to create a comprehensive evaluation method for sewage sludge (SS) treatment and disposal technologies, considering carbon emission and environmental impacts. Life cycle assessment (LCA) were conducted on six SS treatment and disposal technologies in China. The assessments used the IPCC emission factor approach to calculate carbon emissions and the CML2001 method to determine environmental impact factors. Additionally, a colour-coded method was implemented to quantify the evaluation results. The study found that S1 (anaerobic digestion + land application) had the lowest carbon emissions and environmental impact, making it the optimal technology. The S1 scenario had carbon emissions of 669 kg CO₂(t DS)^-1 and environmental impacts of 5.20E-10. A sensitivity analysis was conducted to show the impacts of each unit in the six technologies on total carbon emissions and environmental impacts. The results showed that landfilling has a high sensitivity to carbon emissions and environmental impacts. Therefore, controlling greenhouse gases and toxic substances in sludge landfills is crucial for reducing carbon emissions and environmental pollution.