Lee Chun Man, Lin Xue Rui, Lan Chong Yu, Lo Samuel Chun Lap, Chan Gilbert Yuk Sing
Dep. of Applied Biology and Chemical Technology, Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China.
J Environ Qual. 2002 Sep-Oct;31(5):1502-8. doi: 10.2134/jeq2002.1502.
Landfill leachate recirculation is efficient in reducing the leachate quantity handled by a leachate treatment plant. However, after land application of leachate, nitrification and denitrification of the ammoniacal N becomes possible and the greenhouse gas nitrous oxide (N2O) is produced. Lack of information on the effects of leachate recirculation on N2O production led to a field study being conducted in the Likang Landfill (Guangzhou, China) where leachate recirculation had been practiced for 8 yr. Monthly productions and fluxes of N2O from leachate and soil were studied from June to November 2000. Environmental and chemical factors regulating N2O production were also accessed. An impermeable top liner was not used at this site; municipal solid waste was simply covered by inert soil and compacted by bulldozers. A high N2O emission rate (113 mg m-2 h-1) was detected from a leachate pond purposely formed on topsoil within the landfill boundary after leachate irrigation. A high N2O level (1.09 micrograms L-1) was detected in a gas sample emitted from topsoil 1 m from the leachate pond. Nitrous oxide production from denitrification in leachate-contaminated soil was at least 20 times higher than that from nitrification based on laboratory incubation studies. The N2O levels emitted from leachate ponds were compared with figures reported for different ecosystems and showed that the results of the present study were 68.7 to 88.6 times higher. Leachate recirculation can be a cost-effective operation in reducing the volume of leachate to be treated in landfill. However, to reduce N2O flux, leachate should be applied to underground soil rather than being irrigated and allowed to flow on topsoil.
垃圾渗滤液再循环对于减少渗滤液处理厂处理的渗滤液量很有效。然而，在将渗滤液用于土地后，氨氮的硝化和反硝化成为可能，并且会产生温室气体氧化亚氮（N₂O）。由于缺乏关于渗滤液再循环对N₂O产生影响的信息，因此在中国广州的李坑垃圾填埋场进行了一项实地研究，该填埋场已进行了8年的渗滤液再循环。研究了2000年6月至11月渗滤液和土壤中N₂O的月产量和通量。还研究了调节N₂O产生的环境和化学因素。该场地未使用不透水的顶部衬垫；城市固体废物仅用惰性土壤覆盖，并用推土机压实。在渗滤液灌溉后，在填埋场边界内表土上特意形成的一个渗滤液池中检测到较高的N₂O排放速率（113 mg m⁻² h⁻¹）。在距渗滤液池1 m的表土排放的气体样品中检测到较高的N₂O水平（1.09微克 L⁻¹）。基于实验室培养研究，渗滤液污染土壤中反硝化产生的N₂O至少比硝化产生的N₂O高20倍。将渗滤液池排放的N₂O水平与不同生态系统报告的数据进行比较，结果表明本研究的结果高68.7至88.6倍。渗滤液再循环在减少填埋场中待处理渗滤液的体积方面可能是一种具有成本效益的操作。然而，为了减少N₂O通量，渗滤液应施用于地下土壤，而不是进行灌溉并使其在表土上流动。
