Comparative life cycle assessment of system solution scenarios for residual municipal solid waste management in NSW, Australia

Life cycle assessment (LCA) is a promising tool to evaluate the environmental impacts of different technologies for sustainable waste management. This study employs LCA to assess environmental impacts of alternative scenarios for residual municipal solid waste (MSW) management in New South Wales (NSW) based on current conditions and policies. Six different scenarios including a baseline scenario (landfilling) were applied for NSW waste management for energy production and their impacts on environment. The initial results showed that the scenario 3 that employed anaerobic digestion for food waste, incineration for combustible waste and plastic waste, and landfilling for non-combustible waste produced electricity of 625 kWh/t, which was maximum compared to the other scenarios. LCA results further suggested that among all scenarios, scenario 5 (similar to scenario 3 except combustible waste was treated through gasification and plastic waste was recycled) has the lowest level of environmental burdens in global warming, freshwater and marine ecotoxicity, and human non-carcinogenic toxicity. The sensitivity analysis for energy conversion rates (23-30%) for incineration and plastic recycling rate (66-91.3%) for MSW was further conducted and the results showed that energy conversion rate of 30% makes scenario 3 more valuable for electricity generation and less impactful for ecosystems damage category compared to scenario 5. On the other hand, plastic recycling rate of 91.3% has the lowest environmental burdens and by decreasing recycling rate to 66% the environmental impacts increase; however, it was noticed that reduction in recycling rate does not make any change in the order of scenarios. Overall, the study suggests that each waste type in NSW should be treated with a specific technology to achieve the highest resource recovery and lowest environmental impacts where energy conversion and plastic recycling rates have significant impacts.