Study on reclamation method for a sanitary landfill with environmental problem by semi-aerobic structures

本研究通过对某封闭式垃圾填埋场被动式抽气井内温度和填埋气成分的测量，评价抽气井对垃圾填埋场稳定性的促进作用。多口井显示温度剖面高，甲烷气浓度低。特别是气温上升到60度，检测到高浓度的二氧化碳。这意味着发生了活性好氧生物降解。然后温度下降，气体成分是71%的氮和29%的氧(就像空气一样)。所以这口井周围的区域已经稳定下来了。然而，大多数井显示甲烷浓度高(10%以上)，温度低(不到25度)，以厌氧生物降解为主。通过对温度和填埋气成分的观察，被动式垃圾填埋气提取井对填埋体中的主动好氧生物降解几乎没有贡献。几口井的填埋气剖面显示垂直方向甲烷浓度较高，氧气浓度较低。最后，用数值方法模拟了垃圾填埋气的运移现象。该方法包括对流、扩散和垃圾填埋气的产生。模拟结果较好地反映了垃圾填埋场的气体分布。该井可有助于提取在垃圾填埋体中产生的垃圾填埋气。径向近10m是该井收集垃圾填埋气的区域。模拟结果表明，该井可降低甲烷浓度，增加二氧化碳浓度。

This research examines to measure temperatures and landfill gas components in passive landfill gas extraction wells of a closed landfill and evaluate the effect of the wells for accelerate the stabilization of the landfill. Several wells show the high temperature profile and low methane gas concentration. Especially the temperatures rose up to 60 degrees and high concentration of carbon dioxide was detected. This means active aerobic biodegradation occurred. Then the temperature declined and the gas composition was 71% of nitrogen and 29% of oxygen (like as the air). So the area around this well has stabilized. However, most of the wells show the high concentration of methane (more than 10%) and low temperatures (less than 25 degrees) and anaerobic biodegradation is dominant. Through observations of temperatures and landfill gas components passive landfill gas extraction wells hardly contribute to active aerobic biodegradation in this landfill body. Landfill gas profile in several wells shows the higher concentration of methane and the lower concentration of oxygen in vertical direction.Finally landfill gas transport phenomena simulated by numerical method. The method includes convection, diffusion and generation of landfill gas. Landfill gas profile is well presented by this simulation. The well may contribute to extraction of landfill gas generated in the landfill body. Nearly 10m in radial direction is the area of landfill gas collection by the well. The simulation shows the concentration of methane may decrease and the concentration of carbon dioxide may increase by the well.