庭院垃圾对填埋场甲烷的减量化研究

Mitigation of methane emission from landfill by using yard waste

将熟化时间为24个月和2个月的庭院垃圾分别用于建设0.9 m厚的1#和2#两个生物覆盖层单元,并进行了为期15个月的野外试验,以验证庭院垃圾能否作为生物覆盖层材料用于减少垃圾填埋场甲烷的排放,以及利用同位素和质量守恒方法量化生物覆盖层对垃圾填埋场甲烷的氧化能力.结果表明,两个生物覆盖层对甲烷的氧化能力在建设初期达到整个观测期的最高值,分别为（141±10）g·m-2·d-1和（197±27）g·m-2·d-1,随后生物覆盖单元的甲烷氧化能力随季节交替降低至18～120 g·m-2·d-1和23～70 g·m-2·d-1.试验的中后期,在两个生物覆盖单元中均观测到明显数量的甲烷产出.试验结果表明24个月和2个月熟化时间的庭院垃圾作为生物覆盖填料,均具有较好的甲烷减量化能力,但所含不稳定有机质在厌氧条件下的降解会造成额外的甲烷释放.除此之外,在利用质量守恒方法量化甲烷氧化率时,忽略非甲烷氧化菌的呼吸作用会高估庭院垃圾对甲烷的减量化能力。

Two 0. 9 m thick biocovers marked with 1#and 2#were built by 24-month and 2-month old yard wastes,respectively. A field experiment for 15 months was conducted for validating the capability of yard waste as biocover material and quantifying the oxidative capacity of biocover on mitigating methane emissions from landfills by isotope and mass balance method. Results suggested that both biocovers reached maximum methane oxidation of（ 141± 10） g·m- 2·d- 1and（ 197 ± 27） g·m- 2·d- 1in early tests,and then decreased to 18 ～ 120 g·m- 2·d- 1and 23 ～ 70 g·m- 2·d- 1respectively associated with seasonal variation. Significant amounts of CH4 were generated in both biocovers in the middle and later stages of experiment. Results indicated that biocovers filled with yard wastes had good performance in mitigating CH4 emissions. However,part of unstable organic matter in yard wastes generated CH4 under anaerobic condition. Additionally,the performance of methane mitigation might be overestimated when respiration of nonmethanotrophs was not taken into account.