Geochemical demobilization of metallic pollutants in solid waste—implications for arsenic in waterworks sludges

During stabilization or demobilization of contaminants in solid waste materials, different approaches can be taken, which also can be combined: (1) sufficient long-term buffer capacity can be provided, according to the environmental conditions; (2) permeability for dissolved contaminants can be reduced by secondary mineral precipitations or by soft gels injected into the pore space of the waste body; and (3) new formations of ‘reservoir minerals' can incorporate potential pollutants in their internal structure. Emphasizing the geochemical engineering approach, two examples are presented from the field of water management, both focussing on the demobilization of arsenic species. The first example (after Driehaus, W., 1994. Arsenentfernung mit Mangandioxid und Eisenhydroxid in der Trinkwasseraufbereitung. Vol. 133, Ser. 15, VDI-Reports, Düsseldorf, 117 pp.) relates to the problems during purification of arsenic-rich raw water, suggesting the potential application of iron and manganese oxide minerals as oxidizing agents and mineral lattice structures for the elimination of arsenic. In the second example, contaminated sludges from water treatment plants were investigated for their leaching characteristics and long-term stability. A pH-stat test procedure was used to assess the leaching characteristics of metals at typical pH values. Due to the presence of iron and manganese oxides pentavalent arsenic is protected against conversion into the mobile trivalent form at neutral to low pH. Experimental data suggest that co-disposal with reducing organic matter and alkaline stabilization material or wastes could negatively influence the binding properties and, therefore, should be avoided.     

Integrated use of hydrochemistry and resistivity methods in groundwater contamination caused by a recently closed solid waste site

 In order to investigate the groundwater contamination by solid waste disposal using both hydrochemical and geophysical methods, the Halkalı (I˙stanbul) solid waste disposal site which was closed in 1994 was investigated. The disposal site lies on a ridge between two valleys filled with alluvium. A total of six boreholes were drilled on two lines across the Menekşe valley adjacent to the Halkalı site. Groundwater samples collected from these boreholes were analyzed for various contaminant parameters. The results indicate that TDS and chloride concentrations decrease horizontally away from the waste site whereas they increase with depth. Electrical soundings carried out at 12 locations yielded high resistivity values at the upstream part of Menekşe valley while lower values were obtained from the locations near the leachate seepage points. Received: 11 November 1997 · Accepted: 23 February 1998     

采矿活动对生态环境的污染及治理

通过对国内、国外几个矿区的实例介绍，对历史上采矿活动中对生态环境的污染作了简要的叙述。表明采矿活动对生态环境的污染包括水系、岸边植物、水中微生物、鱼类以及地下水、农业、大气、土壤等，甚至直接危险人体健康，还叙述了采矿污染的原因并简要介绍了几种对采矿污染的治理方法。     

核废物地质处置中岩石选用现状及其开发研究

核废物处置已成为当务之急,其目的是要保证人类与环境的安全。普遍采用的方法是地质处置,即保寻安全封闭的天然屏障。为此,岩石的研究就至关重要。目前,各国选用的岩石不一,并不断变化,主要为石盐、粘土和花岗岩。开发研究总趋势是建立地下实验室,进行现场试验。     

Stability of waste spoils in an area strip mine—geological and geotechnical considerations

Results of investigations into the stability of coal mine spoil consisting of thick clay, saturated sand, and shale overburden in an areal strip mine are presented. Atterberg limits, particle size distributions, and compaction tests were performed to provide index characteristics of the materials. Unconsolidated undrained and consolidated undrained triaxial compression test results on 10·2 cm diameter samples of compacted shale and shale-soil mixtures were used to investigate the short-term and the long-term conditions respectively of the spoil slope. There is evidence that the failure envelope of mine spoil made up of shale or shale-soil mixture is curved. However, stability analyses reveal that the use of strength parameters defined by a linear Mohr-Coulomb envelope yields results that are comparable with those obtained when the non-linear failure envelope is used, provided that such strength parameters are defined at the operating normal stress level on the failure surface. The study illustrates a very good case of spoil instability resulting from very thick overburden soils of low strength and high water content. Results show that the key to achieving stability in such areas lies in an almost total segregation of the soils from the rocks.     

多元桩复合地基在高层建筑地基处理中的应用

介绍了钻孔夯底灌注桩———上部为灌注桩、下部为夯扩桩与钻孔夯扩挤密灰渣土桩相结合形成的多元桩复合地基在某工程中的应用 ,其中利用钻孔夯底灌注桩主要提高承载力和控制建筑物沉降 ,利用钻孔夯扩挤密灰渣土桩主要挤密桩间土 ,降低回填土层压缩性。通过分析计算得出了最佳地基处理方案 ,为类似工程提供了应用实例     

垃圾填埋场设计中的若干问题研究--以襄樊洪山头填埋场为例

襄樊市洪山头垃圾填埋场投资和建设周期均受控于压实粘土坝和渗滤液与沼气收集系统两个关键因素,技术难度大。基于有限元分析结果确定土坝边坡的最佳坡度,采用土工格栅加筋土和包裹式坡面结构新技术加固坝体边坡。介绍一种收集管设置在砾石盲沟内的渗滤液与沼气收集系统,该系统的渗滤液收集和防淤塞能力强,可有效防止收集管弯曲和断裂。     

利用排矸石配制钢纤维高强混凝土的试验研究

大巴沟隧道排矸将对环境造成污染。同时，阜新地区石料相对缺乏，再生利用隧道排矸石和开发新的石料供应基地具有十分重要的现实意义。论文对大巴沟隧道排矸石的物理力学性质进行了试验研究，获得了排矸石的物理力学性能指标。为了进一步研究其力学性质，将其粉碎后，作为粗骨料配制成钢纤维混凝土，并测定其抗压强度和劈裂抗拉强度等指标。利用均匀设计方法对试验结果进行优化，得到了回归方程，具有重要的科学价值。同时得到在此试验条件下，排矸石钢纤维混凝土的抗压强度值可达到83．683MPa，抗拉强度可达到9．378MPa。试验和理论分析结果表明，排矸石钢纤维混凝土具有抗拉强度大、抗变形能力强等特点。可广泛应用于建筑工程、桥梁工程、路基路面工程、港口和海洋工程中。具有广泛的推广应用前景和显著的社会效益、经济效益与环境效益。     

高放废物深地质处置缓冲/回填材料研究进展

综述了高放废物深地质处置库缓冲／回填材料的作用和性能要求。介绍了缓冲／回填材料在透水性、热性质、膨胀性等方面已取得了的成果和新进展。最后简述了缓冲／回填材料研究的发展趋势。     

利用钾长石尾矿制备矿物聚合材料的实验研究

以福建沙县田口钾长石尾矿粉体为主要原料，以煅烧高岭石作配料，硅酸钠作结构模板剂，氢氧化钠作激活剂，进行了制备矿物聚合材料的实验研究，实验样品静置固化7－28d，其抗压强度高达19.4-24.9MPa。耐酸性，耐碱性指标均优于相似建材的国家标准。在配料组成中，控制高岭石用量为20％，适当提高硅酸钠的用量和固／液化，有利于提高制品的力学性能。实验表明，材料抗中度随固化时间的延长而叶抛物线式发展，矿物聚合材料的形成过程为：铝硅酸盐固体组分的溶解络合，分散迁移，浓缩聚合，脱水硬化。由铝硅酸盐凝胶相固化而在的基体相，其化学组成与沸石相近，微观结构极可能与蛋白质类似，物理形态上呈三维网状结构，将未溶解的晶质颗粒胶结为坚硬块体，是矿物聚合材料获得良好力学性能的结构基础。