Analyzing environmental hotspots of proposed landfill extension and advanced incineration facility in Hong Kong using life cycle assessment

• Environmental impacts of major sub-processes of LFE and AIF are evaluated.
• Biological reactions at landfill cells of LFE provide most burden on human health.
• Sludge collection and treatment of LFE incurs most burden on ecosystem quality.
• Among the sub-processes of AIF, stack discharge system influences most.
• Overall, AIF is better than LFE for human health but vice versa for ecosystem quality.

This paper evaluates the environmental impacts and identifies the hotspots associated with the sub-processes of the proposed landfill extension (LFE) and advanced incineration facility (AIF) for municipal solid waste (MSW) disposal in Hong Kong using life cycle assessment methodology. On the basis of the data collected, assumptions made, and system boundary defined, results show that sub-processes of LFE that provide most burdens on human health and ecosystem quality are biological reactions at landfill cells and sludge collection and treatment system, respectively. Meanwhile, stack discharge system in the AIF has highest impact on human health and ecosystem quality. Overall, the LFE performs more poorly than the AIF in view of human health but vice versa for ecosystem quality. The comparison of the LFE and AIF, with and without energy recovery systems, indicates quantitatively that the energy recovery systems provide benefits in regard to climate change, respiratory inorganics and acidification/eutrophication. Energy recovery in the waste sector could be enhanced through technological improvement and economic incentives. The environmental performances by applying Hong Kong's target emission levels for the stack discharge system in the AIF are also more favorable with respect to human health and ecosystem quality than those of Mainland China's and U.S.EPA standards. This study provides an additional view to the stakeholders in decision making process for pledging a sustainable management of MSW disposal in Hong Kong.

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