生活垃圾填埋场恶臭污染的时空变化与膜阻隔效果

Temporal and Spatial Variation in Odor Pollution and Membrane Barrier Effect in Municipal Solid Waste Landfill

为探究生活垃圾填埋场恶臭污染的源特征和时空变化规律,采样分析了东部沿海某填埋场不同暴露状态填埋区域冬夏两季的昼夜间气体样品.定量检测到的各种恶臭物质合计浓度最高可达60000μg·m^(-3),夏季检出的恶臭物质种类多于冬季,且各采样点平均浓度高于冬季30~300倍,其中,硫系物高于冬季4.7~136.7倍.含氧化合物是物质浓度最高的恶臭组分,各采样点硫系物合计浓度不足恶臭物质合计浓度的10%,但换算的理论恶臭浓度贡献率超过理论恶臭合计浓度的90%,甲硫醇和丙硫醇等硫系物是填埋场恶臭污染的关键物质.填埋单元覆膜后堆体表层恶臭物质浓度和理论恶臭浓度随时间呈现出一定的上升趋势,说明覆膜具有一定的恶臭阻隔效果,但填埋单元仍有较大的恶臭释放潜力.相似度分析显示,作业后临时覆盖和未抽气区盖膜单元内累积的恶臭气体可以通过膜搭接缝隙和膜破裂位置等处释放至环境,导致填埋场周边夜间恶臭污染高于白天.

In order to explore the source characteristics as well as the temporal and spatial variations in odor pollution in municipal waste landfills,gas samples were collected from a landfill in an eastern coastal area of China throughout winter and summer.The total concentration of malodorous substances reached 60000μg·m^(-3).There were more types of odor pollutants detected in summer than in winter,the average concentration was 30-300 times higher than that in winter,and the concentration of sulfur compounds increased by 4.7-136.7 times in summer.Oxygenated compounds had the highest concentration,and the total concentration of sulfur compounds accounted for less than 10%of malodorous substances.However,sulfur compounds contributed more than 90%to the theoretical odor concentration.Sulfur compounds such as methyl mercaptan and propane mercaptan were the key odorants in the landfill.After the landfill unit was covered,the concentration of odorous substances and the theoretical odor concentration on the surface of the landfill showed an increasing trend with time,indicating that the covering had a certain odor barrier effect;however,the landfill unit still had a large odor release potential.The similarity analysis showed that the odorous gas accumulated in the unit with temporary cover and without an exhaust system could be released to the environment through the overlapping gap of the membrane and the location of membrane rupture,resulting in more serious odor pollution around the landfill at night than that during the day.