Life cycle assessment of ultra-low emission technologies in China's MSW incineration plants

Incineration is a dominant municipal solid waste (MSW) management method in China, but stricter emission standards necessitate advanced air pollution control (APC) technologies, such as selective catalytic reduction (SCR) and wet scrubbing (WS), into MSW incineration plants to achieve ultra-low emissions (ULE). While effective in reducing targeted air pollutants, these ULE technologies increase energy and material consumption, potentially leading to environmental trade-offs. This study employs life cycle assessment to evaluate these trade-offs by comparing conventional APC systems with ULE technologies in China's MSW incineration plants. Three process inventories, representing a conventional (APCDs1) and two ULE (APCDs2: SCR-first; APCDs3: WS-first) systems, were developed per tonne of MSW incinerated. The footprint methods version 3.1 was applied to assess environmental impacts. The results indicate that the APCDs1 had the lowest overall environmental impact potential (8.37 × 10^-3), followed by the APCDs3 (8.67 × 10^-3) and APCDs2 (8.72 × 10^-3). The increased global warming potential from higher energy and material consumption in ULE systems often outweighs the benefits from reduced air pollutants in other impact categories. This suggests that prioritizing short-process, co-control pollution technologies offering balanced environmental performance may be more sustainable than complex, resource-intensive ULE retrofits in China. The findings provide crucial empirical evidence for informed technology selection and policy development in the MSW incineration sector.