The creosote content of used railway crossties as compared with European stipulations for hazardous waste

Through the history of railways, wooden crossties impregnated with potentially hazardous creosote tar have supported the rails. With impregnated crossties having a lifespan of approximately 50 years, their creosote content is considered as quite safely stored while in dug-down usage. This situation of relative safety does, however, change into acute risk upon replacement and destruction. Carrying a highly flammable content, creosote crossties discharge a pulse of carcinogenic PAH compounds if burnt as ordinary waste. Safe destruction is therefore required if concentrations exceed a critical limit stipulated by the European Union. Since safe destruction is a process of considerable expense, there is a tendency among financial stakeholders to underestimate the creosote content of used railway crossties. In order to actually test whether concentrations generally exceed the critical limit, a set of used creosote ties was therefore sampled while still situated in the railway embankment. With a standard sum of sixteen PAH compounds used as an expression of their total creosote content, the generic concentration was formally inferred and found to significantly exceed the critical limit. The same applies to the fraction of seven carcinogenic PAH compounds, that alone exceed the stipulated limit for hazardous waste. It was also found that the material of railway embankments, whether or not the crossties were used in switches and/or railway yards, and sample depth within the crossties, has a significant effect on creosote concentrations. Regardless of the status of these factors, the concentrations significantly exceed the critical limit that defines hazardous waste within the European Union.     

国内外低、中放射性水平废物管理实践概述及启示

低中放射性水平废物管理是各国面临的长期的、挑战性的问题。本文归纳了监管方式与政策框架、放射性废物分类、处置设施建设、资金管理机制等,概述了国内外低中放射性水平废物管理实践,对比了国内外低中放射性废物管理经验,提出了我国在完善法规体系、优化分类管理、加强技术创新和建立长效资金保障机制等方面的建议。     

水泥窑协同处置危险废物热盘炉技术应用及废液处置路线改造研究

利用水泥窑协同处置危险废物技术,是一种有效、经济的危废处置方式,具有减量化、无害化、资源化等特点。浆渣系统和废液系统是水泥窑协同处置的两种典型技术路线,传统的处置方式是将浆渣直接入分解炉、废液直接入窑头处置,这样通常会引起水泥窑工况波动从而造成处置量偏低。本文主要从浆渣系统和废液系统常规处置路线的缺点进行分析,通过引进热盘炉技术对浆渣系统进行改造,提高浆渣系统的处置量;在此基础上,结合蠕动泵对废液系统处置路线进行改造,将传统工艺无法处置的废液泵送至热盘炉内,从而实现废液处置量的提升。     

Trials on sludge of lime treated spent liquor of pickling unit for use in the cement concrete and its leaching characteristics

Disposal of sludge of lime treated spent liquor pickling unit, as per the Act of Hazardous Waste (Management and Handling) Rules, 1989 is not easy. Its transportation and construction of lined disposal sites pose very severe problem. In the normal practice, sludge is being disposed off on sides of roads and railway tracks to generally fill the low-lying areas. This may cause severe health hazards. An attempt has therefore been made to utilize the treated spent liquor sludge in cement concrete. Design mix M20 has been prepared with varying concentration of sludge in the laboratory. Toxicity characteristics leaching procedure (TCLP) test as per USEPA has been carried out on cement concrete cubes.     

Removal of arsenic(V) from spent ion exchange brine using a new class of starch-bridged magnetite nanoparticles

Ion exchange (IX) is considered by US EPA as one of the best available technologies for removing arsenic from drinking water. However, typical IX processes will generate large volumes of arsenic-laden regenerant brine that requires costly further handling and disposal. This study aimed to develop an engineered strategy to minimize the production and arsenic leachability of the process waste residual. We prepared and tested a new class of starch-bridged magnetite nanoparticles for removal of arsenate from spent IX brine. A low-cost, “green” starch at 0.049% (w/w) was used as a stabilizer to prevent the nanoparticles from agglomerating and as a bridging agent allowing the nanoparticles to flocculate and precipitate while maintaining their high arsenic sorption capacity. When applied to a simulated spent IX brine containing 300 mg/L As and 6% (w/w) NaCl, nearly 100% removal of arsenic was achieved within 1 h using the starch-bridged nanoparticles at an Fe-to-As molar ratio of 7.6, compared to only 20% removal when bare magnetite particles were used. Increasing NaCl in the brine from 0 to 10% (w/w) had little effect on the arsenic sorption capacity. Maximum uptake was observed within a pH range of 4-6. The Langmuir capacity coefficient was determined to be 248 mg/g at pH 5.0. The final treatment sludge was able to pass the TCLP (Toxicity Characteristic Leaching Procedure) based leachability of 5 mg/L as As.     

对城乡规划管理的探索与思考

从城市规划管理的角度，探讨了城市规划的设计层次可分为区域规划、总体规划及控制性详细规划，并从规划管理体制的层面思考了城市规划管理工作，从而适应发展需要。     

Life-cycle flow of mercury and recycling scenario of fluorescent lamps in Japan

A greenhouse pot experiment was conducted to evaluate the feasibility of using biosolids and Lolium perenne for the phytostabilization of copper mine tailings and to evaluate the patterns of metal accumulation and translocation in plants. Biosolids were applied either on the surface or mixed with the tailings at rates of 0, 6, and 12% w/w. All pots were seeded with L. perenne and after six months, the plants were harvested and separated into roots and shoots for metal concentrations analyses as well as some physiological characteristics of the plants. In order to correlate the metal content in plant tissues with some chemical properties, the pore-water of the substrates was analyzed for metals, pH and dissolved organic carbon. Results showed that biosolids application increased the dry biomass production of L. perenne and the shoot concentrations of N and chlorophyll. On the other hand, biosolids increased the concentration of Cu and Zn in the pore-water and in plant tissues. Despite this, there were no evident symptoms of phytotoxicity and the concentration of metals was within the normal ranges described for plants and below the maximum tolerable level for animals. In addition, plant tissue analysis showed that the application of biosolids could significantly reduce Mo uptake and shoot accumulation in plants. The metals were taken up by plants in the following order: Cu>Zn>Mo>Cd. The distribution patterns of metals in plants showed that metals were mainly accumulated in the roots and only a small amount of them were transported to the shoots. These results suggest that mixed application of biosolids (6%) and the use of L. perenne could be appropriate for use in programs of phytostabilization of copper mine tailings. However, these results should be tested under field conditions in order to confirm their efficacy under semi-arid Mediterranean climate conditions.     

项目管理规划初探

介绍了项目管理规划的种类、内容及编制依据，程序和分工，提出了项目管理实施规划的管理要求，分析了项目管理规划与施工组织设计的关系，以期进一步规范建设工程项目管理。     

重庆某矸石山特点及其滑坡防治技术研究

以重庆市为例,结合具体实例,分析了煤矿矸石山对社会及环境造成的灾害,通过调研,论述了对既有矸石山实施治理的必要性,针对性地提出了相应的治理方案并进行了具体阐述,以期改善矿区环境,避免地质灾害隐患。     

Emissions of metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs) from Portland cement manufacturing plants: inter-kiln variability and dependence on fuel-types

Emissions from Portland cement manufacturing facilities may increase health risks in nearby populations and are thus subject to stringent regulations. Direct testing of pollutant concentrations in exhaust gases provides the best basis for assessing the extent of these risks. However, these tests (i) are often conducted under stressed, rather than typical, operating conditions, (ii) may be limited in number and duration, and (iii) may be influenced by specific fuel-types and attributes of individual kilns. We report here on the results of more than 150 emissions-tests conducted of two kilns at a Portland cement manufacturing plant in Portugal. The tests measured various regulated metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs). Stack-gas concentrations of pollutants were found to be highly variable, with standard deviations on the order of mean values. Emission rates of many pollutants were higher when coal was used as the main kiln fuel (instead of petroleum coke). Use of various supplemental fuels, however, had little effect on stack emissions, and few statistically significant differences were observed when hazardous waste was included in the fuel mix. Significant differences in emissions for some pollutants were observed between the two kilns despite their similar designs and uses of similar fuels. All measured values were found to be within applicable regulatory limits.     

Life-cycle assessment of selected management options for air pollution control residues from waste incineration

Based on available technology and emission data seven selected management options for air-pollution-control (APC) residues from waste incineration were evaluated by life-cycle assessment (LCA) using the EASEWASTE model. Scenarios were evaluated with respect to both non-toxicity impact categories (e.g. global warming) and toxicity related impact categories (e.g. ecotoxicity and human toxicity). The assessment addressed treatment and final placement of 1 tonne of APC residue in seven scenarios: 1) direct landfilling without treatment (baseline), 2) backfilling in salt mines, 3) neutralization of waste acid, 4) filler material in asphalt, 5) Ferrox stabilization, 6) vitrification, and 7) melting with automobile shredder residues (ASR). The management scenarios were selected as examples of the wide range of different technologies available worldwide while at the same time using realistic technology data. Results from the LCA were discussed with respect to importance of: energy consumption/substitution, material substitution, leaching, air emissions, time horizon aspects for the assessment, and transportation distances. The LCA modeling showed that thermal processes were associated with the highest loads in the non-toxicity categories (energy consumption), while differences between the remaining alternatives were small and generally considered insignificant. In the toxicity categories, all treatment/utilization options were significantly better than direct landfilling without treatment (lower leaching), although the thermal processes had somewhat higher impacts than the others options (air emissions). Transportation distances did not affect the overall ranking of the management alternatives.     

网络计划技术在投标工作中的应用

介绍了网络计划的重要性及网络计划的编制程序，结合工程实例探讨了投标工作中网络图的绘制及应用，对网络图在施工组织设计中的作用进行了重点阐述，以提高网络计划技术在投标工作中的应用水平。     

浅谈施工组织设计

介绍了施工组织设计的概念和分类，探讨了施工组织设计的编制要点及管理方法，阐明了编制施工组织设计的重要性，表明了施工组织设计对于工程项目具有重大作用。     

流溪河灌区用水计划在执行中的建议

结合广州市流溪灌区的实际用水情况,对灌溉计划用水的管理工作提出了建议,阐述了灌溉计划的执行要掌握的三个环节,分析了现阶段灌溉管理要注意和存在的问题,以加强灌溉管理,提高灌溉水的有效利用率。     

浅谈市政工程中安全技术措施的编制与实施

对安全技术措施及重要性进行了介绍，从调查分析、编制审批、交底实施、监督检查、总结完善五个阶段阐述了市政工程中安全技术措施的编制与实施，以增强对事故预测预控的可靠性，促进企业的安全生产管理。     

德国建筑废弃物层级管理及其对中国的启示

分析德国建筑废弃物层级管理的基本框架内容,从防止产生、再利用、再生利用、处置等方面剖析影响建筑废弃物各层级管理有效实施的因素,在此基础上提出我国的建筑废弃物管理应借鉴德国的成熟经验,通过明确和细化我国建筑废弃物管理的层级结构,优先强调建筑废弃物的源头预防与控制,构建健康有序的再生建筑产品市场,合理运用经济工具规制建筑废弃物处置来有效推进建筑废弃物的层级管理。     

项目管理实施规划在施工项目管理中的作用

分析了项目管理实施规划管理的必要性和重要性，介绍了项目管理实施规划编制的重点及应注意的有关问题，分析了实施规划的效益，从而促进企业的规范化管理。     

南京市垃圾分类体系试行现状与改善建议

以南京市垃圾分类锁金社区试点为例,重点调查了垃圾分类政策实施的各个环节,通过实地调研及相关部门的访谈了解到垃圾分类在各个环节所取得的成果以及相应存在的问题,并且客观分析评价了南京市目前的垃圾分类处理系统：在垃圾分类管理及终端处理等方面提出了相关改善建议。