Department of Civil, Construction, and Environmental Engineering,North Carolina State University, Campus Box 7908, Raleigh, North Carolina 27695-7908, United States.
Environ Sci Technol. 2021 Oct 19;55(20):13583-13592. doi: 10.1021/acs.est.1c02526. Epub 2021 Oct 1.
Landfills receive over half of all U.S. municipal solid waste (MSW) and are the third largest source of anthropogenic methane emissions. Life-cycle assessment (LCA) of landfills is complicated by the long duration of waste disposal, gas generation and control, and the time over which the engineered infrastructure must perform. The objective of this study is to develop an LCA model for a representative U.S. MSW landfill that is responsive to landfill size, regulatory thresholds for landfill gas (LFG) collection and control, practices for LFG management (i.e., passive venting, flare, combustion for energy recovery), and four alternative schedules for LFG collection well installation. Material production required for construction and operation contributes 68-75% to toxicity impacts, while LFG emissions contribute 50-99% to global warming, ozone depletion, and smog impacts. The current non-methane organic compound regulatory threshold (34 Mg yr) reduces methane emissions by <7% relative to the former threshold (50 Mg yr). Requiring landfills to continue collecting LFG until the flow rate is <10 m min reduces emissions by 20-52%, depending on the waste decay rate. In general, for landfills already required to collect gas, collecting gas longer is more important than collecting gas earlier to reduce methane emissions.
垃圾填埋场接收了美国超过一半的城市固体废物（MSW），是人为甲烷排放的第三大来源。垃圾填埋场的生命周期评估（LCA）由于废物处置、气体产生和控制的持续时间长，以及工程基础设施必须执行的时间长而变得复杂。本研究的目的是开发一个具有代表性的美国 MSW 垃圾填埋场的 LCA 模型，该模型对垃圾填埋场的规模、垃圾填埋气（LFG）收集和控制的监管阈值、LFG 管理实践（即被动通风、火炬燃烧、能源回收燃烧）以及 LFG 收集井安装的四个替代时间表具有响应能力。建设和运营所需的材料生产对毒性影响的贡献为 68-75%，而 LFG 排放对全球变暖、臭氧消耗和烟雾影响的贡献为 50-99%。当前非甲烷有机化合物监管阈值（34 Mg yr）使甲烷排放量相对于前一个阈值（50 Mg yr）减少了<7%。要求垃圾填埋场继续收集 LFG，直到流量<10 m min，这将根据废物衰减率减少 20-52%的排放。一般来说，对于已经需要收集气体的垃圾填埋场，延长收集气体的时间比提前收集气体更重要，以减少甲烷排放。
