Geotechnical properties of municipal solid waste at different phases of biodegradation

This paper presents the results of laboratory investigation conducted to determine the variation of geotechnical properties of synthetic municipal solid waste (MSW) at different phases of degradation. Synthetic MSW samples were prepared based on the composition of MSW generated in the United States and were degraded in bioreactors with leachate recirculation. Degradation of the synthetic MSW was quantified based on the gas composition and organic content, and the samples exhumed from the bioreactor cells at different phases of degradation were tested for the geotechnical properties. Hydraulic conductivity, compressibility and shear strength of initial and degraded synthetic MSW were all determined at constant initial moisture content of 50% on wet weight basis. Hydraulic conductivity of synthetic MSW was reduced by two orders of magnitude due to degradation. Compression ratio was reduced from 0.34 for initial fresh waste to 0.15 for the mostly degraded waste. Direct shear tests showed that the fresh and degraded synthetic MSW exhibited continuous strength gain with increase in horizontal deformation, with the cohesion increased from 1 kPa for fresh MSW to 16–40 kPa for degraded MSW and the friction angle decreased from 35° for fresh MSW to 28° for degraded MSW. During the triaxial tests under CU condition, the total strength parameters, cohesion and friction angle, were found to vary from 21 to 57 kPa and 1° to 9°, respectively, while the effective strength parameters, cohesion and friction angle varied from 18 to 56 kPa and from 1° to 11°, respectively. Similar to direct shear test results, as the waste degrades an increase in cohesion and slight decrease in friction angle was observed. Decreased friction angle and increased cohesion with increased degradation is believed to be due to the highly cohesive nature of the synthetic MSW. Variation of synthetic MSW properties from this study also suggests that significant changes in geotechnical properties of MSW can occur due to enhanced degradation induced by leachate recirculation.     

垃圾填埋场填埋气产生与迁移计算机模拟

准确预测填埋场内填埋气随时间和空间的变化规律,对填埋场的管理和填埋气的合理应用具有重要作用.以多孔介质流体动力学理论为基础,构建了填埋场中气体迁移转化过程三维模型.应用有限单元法和迭代法对模型的非线性方程组进行了求解,计算了填埋场中气体的压力分布情况.结果表明,填埋初期气压随深度和时间的增加而增加;而后气压随时间增加逐渐减小.     

A mathematical model to estimate errors associated with closed flux chambers

Errors associated with the closed flux chamber technique, used to measure surface emissions from landfills, were investigated by using a combination of numerical modeling and laboratory studies. A transient-state, advective–dispersive–reactive model was developed and used in conjunction with its steady-state version to quantify the errors associated with closed flux chambers. In developing the model, all four major gases, CH₄, O₂, CO₂, and N₂, and the oxidation of CH₄ to CO₂ were considered. Laboratory experiments were conducted on a monolayered as well as a two-layered landfill cover system to calibrate and verify the model. The model was used to develop a plot of the percentage errors associated with closed flux chambers of different dimensions and surface flux rates.     

人工湿地系统在垃圾渗滤液处理中的应用

介绍了人工湿地的组成和类型,人工湿地去除渗滤液中有机物、氮、磷和重金属的机制。分析了影响人工湿地处理渗滤液效率的因子,并且结合人工湿地设计和运行维护提出了相关建议。根据国内外成功的工程实例,分析了人工湿地处理垃圾渗滤液的经济优势、生态优势,展示了该处理技术广泛的应用前景,对以后的研究进行了展望。     

垃圾填埋与焚烧渗滤液全(多)氟化合物赋存特征

采样分析了来自中国西南地区6个生活垃圾填埋场的渗滤液、3个生活垃圾焚烧厂的渗滤液原液及场内处理出水，发现3种水样中17种全（多）氟化合物（PFAS）浓度分别在1805~43310，7228~16565和55~185ng/L之间；呈现以全氟丁烷羧酸（PFBA）和全氟丁烷磺酸（PFBS）等短链、偶数链PFAS为主的污染特征.对比位于相近地理区域的焚烧厂和填埋场渗滤液，发现两者PFAS组成类似，而前者PFAS浓度与运行时间为2a的填埋场渗滤液相似，高于运行时间较长（15a）的填埋场渗滤液.研究结果将为我国西南地区垃圾渗滤液PFAS赋存现状提供基础信息，并为预防和控制PFAS产品生产和使用带来的环境污染提供重要数据支持.     

简易生活垃圾填埋场污染的控制

结合工程实例的介绍,阐述了简易生活垃圾填埋场的污染、危害及其控制的主要工程措施,指出了实现减量化、稳定化、无害化是我国该类填埋场污染治理的根本思路。     

填埋垃圾和渗滤液中CH4氧化菌的丰度研究

应用实时荧光定量聚合酶链式反应(Real-Time Quantitative Polymerase Chain Reaction,简称实时荧光定量PCR)技术对填埋场垃圾和渗滤液中CH₄氧化菌的pmoA基因进行定量分析. 结果表明:实时荧光定量PCR技术可用于渗滤液和垃圾中CH₄氧化菌的定量分析. 对于厌氧和准好氧填埋,初期渗滤液中CH₄氧化菌的数量均高于稳定期;准好氧填埋体渗滤液中CH₄氧化菌的数量均高于厌氧填埋体. 准好氧填埋垃圾中CH₄氧化菌的数量随着填埋龄的增加呈先增加后降低的趋势,并在填埋后的9个月左右达到最大值,与准好氧填埋体CH₄产生的规律相似. 同时,准好氧填埋垃圾中CH₄氧化菌的数量随着距导气管距离的增加而降低,但不同填埋时期的变幅不同,与准好氧填埋体O₂和CH₄的迁移规律有关. 此外,对渗滤液和垃圾样品的研究表明,准好氧填埋体垃圾填埋层内部存在大量的CH₄氧化菌,具有显著的CH₄氧化能力.      

小城镇生活垃圾填埋场优化布点

运用系统的观点对小城镇生活垃圾填埋场选址进行多因素、多层次的分析,建立了小城镇生活垃圾填埋场综合评判系统的层次结构模型,确定了小城镇生活垃圾填埋场布点的适宜度等级。以重庆市小城镇为研究对象,以区域性联合集中处理为前提,以22.2 km为县域镇区域联合半径,利用ArcCatalog和ArcMap软件对所收集到的数据进行了图形数字化、关键区域的提取、缓存区分析、建设地形适宜度分析和地质灾害区划分析,并进行了各影响因素图层的叠加计算和关键区域的叠加计算,最终得到了重庆市小城镇填埋场优化布点图,为有关部门提供决策支持。     

矿化垃圾中氧化甲烷兼性营养菌的筛选与生物特性研究

从填埋了10 a的矿化垃圾中分离得到1株能以甲烷为碳源和能源生长的菌株DH,经NCBI比对发现,该菌株的16S rDNA序列与微杆菌(Microbacterium sp.)3个菌株的同源性在99%以上.目前该菌株已经在中国典型培养物保藏中心申请了专利保藏,保藏号为M2010099.微杆菌DH具有极强的温度耐受性,最佳培养pH为6.5,以甲烷为碳源可实现高密度生长,菌液D560 nm值可达到1.1～1.2.微杆菌DH对甘露糖、果糖和葡萄糖3种单糖以及蔗糖和乳糖2种双糖的利用效果较好.当以蔗糖和甘露糖为碳源时,菌液D560 nm值分别达到了0.758和0.742.与对照组相比,喷洒DH菌液可以提高矿化垃圾的甲烷氧化率1倍以上.微杆菌DH的发现克服了专一营养甲烷氧化菌难于扩大培养、活性低等工程应用问题,为该类细菌在实际工程应用提供了生物学基础.