呼吸型填埋场覆盖层技术研究Ⅰ:热动力自充氧装置构建

Development of a breathing landfill biocover technique I:Construction of passive air venting system based on aerothermodynamics

填埋场最终覆盖层(以下简称"覆盖层")中的氧气含量是影响甲烷氧化效果的重要因素.本研究基于空气热力学原理提出了一种呼吸型覆盖层技术,构建了利用垃圾堆体与外界环境的温差而实现覆盖层自充氧的热动力自充氧装置,并优化了其空气/氧气充气效率.结果表明,导气管路内空气流速(v)与温差(ΔT)呈线性关系(v=0.0281ΔT-0.5258),增加导气管路长度和进气管径可提升自充氧效果,本研究中实验所得的导气管路内最大空气流速为2.0m·s-1(温差35℃、导气管长2.5m).热动力自充氧装置应用于模拟覆盖层时,40cm厚的自充氧覆盖层内各层O2含量始终大于20%,而对照覆盖层内最低O2含量为15.7%,自充氧技术有效地改善了模拟覆盖层内O2的分布状况.基于该技术开发的热动力自充氧装置克服了传统覆盖层技术中含氧层浅的瓶颈,为填埋场覆盖层控制温室气体排放提供了改进手段和发展方向.

Oxygen （O2） content is a key factor for methane oxidation in landfill cover layer.In this study,a breathing landfill biocover technique was proposed.A passive air venting system based on aerothermodynamics was constructed as the key component of the breathing biocover system,and its air/O2 supply efficiency was optimized.The result showed that the air velocity in venting pipe has a linear relationship with the temperature discrepancy （V=0.0281ΔT-0.5258）.The air velocity in the venting pipe can be further improved by increasing the length of the vertical venting pipe and diameter of horizontal inlet pipes.The highest velocity （2.0 m·s-1） was achieved at the temperature discrepancy of 35 ℃ and with a 2.5 m vertical venting pipe.When the passive air venting system was introduced into a simulated landfill cover reactor,it significantly improved the level and distribution of O2 in 40 cm cover layers as the data showed that the average O2 content in every layer kept more than 20%,while that was 15.7% in the control trail.The study proved that this novel breathing biocover can be applied as an effective way for greenhouse gas emission control in landfill by enhancing biodegradation of methane in landfill gas.