城市生活固体废弃物处置规划和场地选址方向探讨

城市生活固体废弃物已成为重要环境污染问题之一,地质环境工作应为废弃物的填埋选址,防治污染提供服务。北京地质环境部门受北京市主管部门委托开展了全市生活固体废弃物填埋场地适宜性区划,卫生填埋场地环境地质影响评价,其成果已为市规划、环境行政部门所利用。     

西安市固体废弃物卫生填埋场建设中的环境岩土工程问题研究

人与环境的和谐共处是当今社会可持续发展的重要内容,面对城市固体废弃物激增所带来的人与环境之间的各种问题,卫生填埋法作为最广泛也是最彻底的固体废弃物处理方法得到了越来越多的关注和研究。卫生填埋场的建设与环境岩土工程领域内的诸多方面密切相关,针对卫生填埋场的建设中涉及到的环境岩土工程问题,在依据已有资料概括介绍国内外相关发展现状的同时,结合西安地区的特点,在填埋场场址和类型选择、废弃物工程性质指标、填埋场防渗处理、填埋场沉降计算和边坡稳定这5个方面对西安地区城市固体废弃物卫生填埋场建设中的环境岩土工程问题进行了论述,提出了相应建议,展望了研究方向。     

考虑生物降解的填埋场长期沉降研究

填埋场沉降是环境岩土工程主要研究课题,填埋场沉降主要由堆载瞬时沉降、与时间有关的填埋体骨架蠕变和有机物生物降解引起的沉降等3部分组成。迄今为止,国内外学者建立了许多估算填埋体沉降的数学模型。根据总结归纳的典型填埋体沉降计算模型,结合某填埋场沉降实测资料,探讨了计算模型的适用性。     

生活垃圾填埋过程中的沉降分析与计算

结合生活垃圾PTH蠕变方程式中的相关参数,依据重庆市长生桥垃圾卫生填埋场的填埋工艺和填埋方案,得出填埋历程与填埋高度的关系曲线。通过与土压缩理论计算方法相比较发现,土压缩理论中参数选取主要以经验为主,假设条件也与实际情况不符,而PTH蠕变模型中各参数均可由室内压缩蠕变试验得出,依据充分。计算表明,重庆市长生桥垃圾卫生填埋场在填埋过程中产生的沉降达25.72%,在容量估算中如果忽略这一数据则会对填埋场的经济性分析产生一定影响。     

南京市生活垃圾处置场适宜性评价及环境地质问题

通过南京市生活垃圾处置场现状调查评价与选址课题研究,基本查明了南京市生活垃圾填埋的历史与现状、填埋量、填埋场分布;用层次分析法对正在使用的6个填埋场进行适宜性评价,有三分之二的填埋场地表水、地下水遭受不同程度的污染,尤其是轿子山垃圾填埋场的运营对南京东郊地下水源地影响较大。分析了导致污染的主要环境地质问题,对已污染填埋场的治理和未来填埋场的选址具有指导意义。     

岩溶地区垃圾填埋场的选址评价探讨

岩溶地区的垃圾填埋选址较为困难,现行的垃圾填埋场选址评价方法又存在较大局限。笔者等依据垃圾填埋场的建设宗旨和选址基本原则,结合岩溶地区的环境地质特点,探讨提出一套适用于岩溶地区的垃圾填埋场选址评价方法。通过实例应用表明,该方法可在现行较难选出垃圾填埋场的岩溶地区,优选出适宜性较好的未来垃圾填埋场,能够担当起解决岩溶地区的垃圾无害化、减量化填埋处置的难题和重任。     

威海市城市垃圾填埋场选址地质环境适宜性评价

威海是＂最适宜人类居住的地方＂,但随着城市建设的快速发展,城市垃圾产生量不断增加,垃圾填埋场选址问题亟待解决。以威海市环翠区为研究对象,综合考虑地形地貌、土地利用规划、交通、水利规划、气象、地质、水文地质、工程地质、环境地质等多方面因素及经济效益和环境效益,从地质环境角度出发,选取5个层次共15个评价因子,采用层次—网格法进行了垃圾填埋场选址区划分析研究,划分出垃圾可填埋区、限制填埋区、禁止填埋区。并在限制填埋区和可填埋区,进一步优选出几个垃圾填埋场地的首选场址,可供规划、设计部门参考。     

淮安市垃圾填埋场地质特征及其防渗评价

正确分析评价垃圾填埋场的地质特征和防渗方案,对垃圾填埋场的选址、设计以及施工运营极为重要。从自然环境、地层结构及岩性特征等方面阐述了淮安市某垃圾填埋场的地质特征,分析了填埋区含水层分布、厚度、赋水性等水文地质条件;结合室内试验和野外试验,综合确定了填埋区岩土层渗透系数大于1×10^-7cm／s,表明填埋区不具备天然防渗的条件,需采用人工防渗系统才能有效的阻滞垃圾渗滤液对周边环境的影响。     

某危险废物安全填埋场的设计与工艺

通过某危险废物安全填埋场项目,介绍了安全填埋工程的总体设计工艺,包括危险废物填埋处置总体流程、预处理系统、填埋库体结构、防渗系统、终场覆盖及环境监测等。结合工程设计实践,探讨了危险废物填埋场设计工艺要点。分析认为在沿海软土地区,采用双衬层水平防渗和垂直防渗相结合的半刚性结构方式,可以达到有效保护库区环境的目的。     

城市固体废弃物填埋场的岩土工程问题

论述了国内外城市卫生填埋场相关的岩土工程问题及其研究现状,包括卫生填埋场填埋体物理力学性质、卫生填埋场的防渗系统和边坡稳定等一系列岩土工程问题,在此基础上初步探讨了我国城市卫生填埋场相关岩土工程问题的发展前景。     

垃圾填埋场地特征及其工程地质问题分析

以徐州某垃圾填埋场工程为例,以勘察工作成果为基础,对区域稳定性、地震效应等方面进行了探讨。重点研究和评价了水文地质条件,分析了垃圾填埋场建设所涉及的主要工程地质问题。研究结果表明:本场地的变形特性、边坡稳定性等满足填埋场使用要求,不会出现承压水突涌现象,填埋场的修建不会对地下水产生不良影响,场地作为垃圾填埋场的建筑场地是适宜的。      

Analysis of flow behavior in a landfill with cover soil of low hydraulic conductivity

 This paper presents the results of field tests of hydrologic parameters in a landfill and the results of numerical simulation to find the efficiency of the pumping method to reduce leachate levels in the landfill. The field hydraulic conductivity and storativity of waste and buried cover soils in the landfill are measured by pumping and slug tests. The hydrologic condition inside the landfill is first calibrated using the drawdown-time curve obtained from the pumping test, and the flow behavior of leachate during pumping in the landfill, when various layers of waste and buried cover soil exist, is analyzed through three-dimensional numerical simulation of flow. The results of the field investigation show that the buried cover soil of low hydraulic conductivity forms an impermeable layer preventing the downward flow of leachate and upward flow of landfill gas. The hydraulic conductivities of the pumping test and slug tests were quite close on the same order of magnitude. It was also possible to match the drawdown-time data of the field tests with those of the model using input data close to the hydrologic property obtained from the field tests. The numerical flow analysis showed that pumping was possible up to 120 tons/day for a single well without a drain, while the pumping rate could be increased to 300 tons/day for the same well with the drain. From the vertical section of the flow vector with a horizontal drain, the barrier role of buried cover soil is identified, which was proposed by examining the water contents of the disposed cover soil and waste in the field. Received: 15 May 1998 · Accepted: 4 January 1999     

层次分析法在垃圾填埋场适宜性评价中的应用

中国生活垃圾填埋场以简易填埋场为主,已对环境造成了一定污染,垃圾填埋场地的适宜性越来越受到重视.本文在对河北省县级以上城镇生活垃圾填埋场调查的基础上,首次采用层次分析法,综合考虑地质环境条件、垃圾填埋场自身条件、环境保护条件、经济条件、场地条件五大因素,对河北省垃圾填埋场的适宜性进行了评价,提出了一套评价标准.通过实例应用表明,该方法选取的评价因素较全面,客观反映了河北平原垃圾填埋场的实际情况,取得了较满意的评价结果.     

Modeling municipal solid waste landfill settlement

A good prediction of solid waste landfill settlement is important for landfill design and rehabilitation. A one-dimensional model which accounts for mechanical settlement and biodegradation processes is developed to simulate the settlement behavior of municipal solid waste landfill. The derivation of analytical solutions for specific conditions is introduced. The numerical approach, capable of coping with more general conditions, is also presented to estimate the spatial and temporal distribution of landfill settlement. The proposed model can simulate typical features of short- and long-term landfill settlement behaviors. With proper selection of parameter values, field measurements are well simulated by this model. The effects of some design parameters on the settlement behavior of municipal solid waste landfills are also examined with the help of this model.     

Behavior of a municipal landfill from field measurement data during a waste-disposal period

The behavior of a municipal waste landfill on marine clay was analyzed from field measurement data. Instruments, e.g., a groundwater level sensor, piezometer, earth pressure gauge, settlement plates, inclinometer, etc., were installed and operated during the disposal period from October 1992 to November 2000. A database system was developed to manage the data from this landfill using Access (Microsoft) with Delphi programs. From the analyses, it was determined that the settlement of the landfill during the initial period of waste disposal was small because of the high leachate level in the landfill. As the level of waste became higher than the leachate level, the settlement of the landfill increased significantly due to the increasing effective pressure within the landfill. From a stability point of view, the critical time for the landfill in this study was the initial period of landfill disposal, which was caused by either the impact load of waste disposal or the time schedule of waste disposal, which was faster than the consolidation of foundation clay caused by the waste load.     

Field-monitored settlement and other behavior of a multi-stage municipal waste landfill, Korea

The behavior of the Gimpo #2 landfill, which is an active landfill and the largest in Korea, is analyzed using field measurement data obtained from various field instruments installed within the landfill. The data included in this analysis are the leachate head within the landfill, waste load data using soil pressure plate and settlement data from settlement plate on the surface of the waste of each stage fill including the settlement of the soft foundation clay soil. Landfill blocks are selected both near the embankment and in the center area of the landfill. The analysis of the field-monitored data showed that the leachate head increase was negligible near the embankment. It was significant in the central block as the waste loads increase and reached 15 m at the fourth stage of waste disposal. The reason that the leachate head is higher in the central block than near the embankment is due to the long drainage path and the loss of gradient of drain pipes. The range of unit weight of the waste converted from the measurement data of earth pressure cell was 0.91–1.24 t/m³ and the average value was 1.05 t/m³. The values reflect well the waste compositions recently buried in GML #2, since from 1998 the waste disposed in GML #2 did not contain food waste. The magnitude of final settlements that occurred in each stage loading of 5 m thickness in the peripheral block was very close to 120 cm. The settlement rate of the waste by dividing the thickness of waste was 24 %. This rate can be divided into 10 % by waste loading and 14 % by waste decomposition. The delay of settlements is recognized in each waste layer for second and third loading in the central block due to the accumulation of leachate within the landfill.     

Shear strength characterization of municipal solid waste at the Suzhou landfill, China

The current practice of slope stability analysis for a municipal solid waste (MSW) landfill usually overlooks the dependence of waste properties on the fill age or embedment depth. Changes in shear strength of MSW as a function of fill age were investigated by performing field and laboratory studies on the Suzhou landfill in China. The field study included sampling from five boreholes advanced to the bottom of the landfill, cone penetration tests and monitoring of pore fluid pressures. Twenty-six borehole samples representative of different fill ages (0 to 13 years) were used to perform drained triaxial compression tests. The field and laboratory study showed that the waste body in the landfill can be sub-divided into several strata corresponding to different ranges of fill age. Each of the waste strata has individual composition and shear strength characteristics. The triaxial test results showed that the MSW samples exhibited a strain-hardening and contractive behavior. As the fill age of the waste increased from 1.7 years to 11 years, the cohesion mobilized at a strain level of 10% was found to decrease from 23.3 kPa to 0 kPa, and the mobilized friction angle at the same strain level increasing from 9.9° to 26°. For a confinement stress level greater than 50 kPa, the shear strength of the recently-placed MSW seemed to be lower than that of the older MSW. This behavior was consistent with the cone penetration test results. The field measurement of pore pressures revealed a perched leachate mound above an intermediate cover of soils and a substantial leachate mound near the bottom of the landfill. The measurements of shear strength properties and pore pressures were utilized to assess the slope stability of the Suzhou landfill.     

Electromagnetic methods to characterize the Savoia di Lucania waste dump (Southern Italy)

The aim of this work is the joint application and integration of non-invasive geoelectrical methods for studying the landfill of Savoia di Lucania (Southern Italy). This landfill for its engineering features and small dimensions (70 m × 30 m × 6 m) represents an optimal test site to assess a geophysical survey protocol for municipal solid waste landfills investigation and monitoring. The landfill of Savoia di Lucania has been built with a reinforced concrete material and coated with a high-density polyethylene (HDPE) liner. Three electrical resistivity tomographies (ERT), two self-potential (SP) map surveys and one induced polarization (IP) section have been performed, both in the surrounding area and inside the waste landfill. The geophysical investigations have well defined some buried boundaries of the landfill basin and localized the leachate accumulation zones inside the dumpsite. Comparison of our results with other engineering and geological investigations could be the key for evaluating the integrity of the HDPE liner. Finally, the joint use of the ERT, IP and SP methods seems to be a promising tool for studying and designing new monitoring systems able to perform a time-lapse analysis of waste landfill geometry and integrity.     

A comparative study of waste landfill disposal in different countries

This study draws attention to the fact that natural processes can mobilize thallium （Tl）, a highly toxic metal, which may enter the food chain with severe health impacts on the local human population. A rural area having independent Tl mineralization in southwestern Guizhou, China, was chosen for a pilot study. Tl contents of soils extracted by HNO3 in the study area range from 35-165 mg/kg in soils from the mining area, 14-78 mg/kg in alluvial deposits downstream, and 〈0.2-0.5 mg/kg in soils from the background area. Tl contents in ammonium acetate EDTA-extracted fraction are 0.013-1.3 mg/kg, less than 1% of concentration in HNO3-extracted fraction. The amounts of Tl in NH4Ac-extracted fraction were thought to be more exchangeable and bioavailable, i.e., immediately available to plants and/or available to plant roots over a period of years. Tl concentration in crops exhibits species-dependent preferences. The enrichment of Tl in edible crop species decreases in the following order： green cabbage〉chili〉Chinese cabbage〉rice〉com. The highest level of Tl in green cabbage is up to 500 mg/kg （DW）, surpassing the values of Tl in the soils （13-59 mg/kg）. The enrichment factor for TI in green cabbage is up to 1-10 when considering the HNO3-extracted Tl, but the factor highly rises to 30-1300 while considering the NH4Ac-extracted Tl. The average daily uptake of Tl by the local villagers through consumption of locally planted crops was estimated at about 1.9 mg per person, which is 50 times the daily ingestion from the Tl-free background area.