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.     

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。     

运用对策论分析和思考城市更新的若干问题

对策论是一种重要的社会科学研究方法,在经济、社会、环境等领域有广泛的应用。该文在介绍对策论基本内容的基础上,运用对策论理论分析城市更新中的一些典型问题,进而从对策论求解的角度提出改善措施,最后通过城市更新实例来说明该措施的可操作性。     

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.     

国外“无废城市”的相关理论、评价方法与实践经验

消费驱动的生活模式导致城市废物问题日益严峻,促使城市向无废化转变成为城市研究与实践领域的重要问题。论文梳理了国外有关无废城市的相关研究,首先辨析了无废城市的概念、内涵与相关理论,其次分类介绍了国外评价无废城市的指标体系,最后从如何引导、谁来买单、系统怎样、谁更有效4个角度,阐述了国外城市无废化实践的相关经验。     

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.     

基于博弈论的建设工程投标报价模型分析

从投标报价行为的竞争性角度对最低价中标机制下投标者的报价问题进行研究。在分析报价博弈过程的基础上,建立了基于不完全信息博弈论的报价数学模型,结合企业追求期望利润最大化的目标,对企业竞标成功的概率进行详细的分析,并给出了满足企业期望效益最大的最优报价方法。     

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.     

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.     

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。     

从博弈观点论北台湾历史街区保护中参与者的反身性

从博弈观点赛局理论之角度探讨北台湾历史街区保护规划设计中参与者的角色与立场之转变,从不合作赛局的冲突,转变为半合作赛局的妥协,到合作赛局的均衡解,寻求互利共荣的规划设计与施工过程,探讨历史街区保护规划中参与者的反身性与能动性.     

城市规划实施的博弈分析及立法建议

城市规划行政审批中主管部门与开发建设单位之间存在大量的利益博弈现象,基于双方合意的均衡博弈结果的形成有赖于"激励与制约"共有的法律机制的建立,为此,需将政务公开与信息共享纳入法制轨道,设计有效的规划许可审批程序,确立重大事项听证制度和说明理由制度,建立城市规划实施效果预测制度.     

建筑垃圾管理:一个有待重视的领域

随着我国经济的高速发展,建筑垃圾不断增加,已占了城市固体垃圾的很大一部分比例。提出了对建筑垃圾应该加强管理,从建筑垃圾产出的源头要做减量化的工作,在建筑垃圾的下游应该做资源化的管理,这对于建筑业的可持续发展有着重要的意义。     

Solid wastes generation in India and their recycling potential in building materials

Presently in India, about 960 million tonnes of solid waste is being generated annually as by-products during industrial, mining, municipal, agricultural and other processes. Of this ∼350 million tonnes are organic wastes from agricultural sources; ∼290 million tonnes are inorganic waste of industrial and mining sectors and ∼4.5 million tonnes are hazardous in nature. Advances in solid waste management resulted in alternative construction materials as a substitute to traditional materials like bricks, blocks, tiles, aggregates, ceramics, cement, lime, soil, timber and paint. To safeguard the environment, efforts are being made for recycling different wastes and utilise them in value added applications. In this paper, present status on generation and utilization of both non-hazardous and hazardous solid wastes in India, their recycling potentials and environmental implication are reported and discussed in details.     

Is production outside management?

It is contended that the root cause for disagreement between lean construction proponents and management scholars is related to the new direction of management research which was proposed in 1959 in two influential books, by R.A. Gordon and J.E. Howell and by F.C. Pierson. It was argued that management was to be approached through three root stems: behavioural science, economics and quantitative modelling. The mainstream academic work on management has followed the guidelines presented in these books. Unfortunately, this kind of management science has also attracted vocal and wide criticism regarding its practical relevance. The 1959 work rejected the production-centric scientific management tradition – a tradition on which lean construction has been based. Thus, the underlying disagreement is about the role of production in management: is production a starting point for management or outside management? This root disagreement is demonstrated through two research topics at the heart of the development of management science after 1959: organizational theory, as developed by J.R. Galbraith, and transaction cost economics, initiated by O. Williamson. Based on evidence from the analyses made, it is suggested that the failure to include production in theory has been one major cause for the problematic situation of management science in the last 50 years.

Il est soutenu que la cause première du désaccord entre les partisans de la construction rationalisée et les chercheurs en gestion est liée à la nouvelle orientation de la recherche en gestion qui a été proposée en 1959 dans deux livres influents de R.A. Gordon et J.E. Howell et de F.C. Pierson. Il était avancé que la gestion devait être abordée selon trois branches principales: les sciences du comportement, les sciences économiques, et la modélisation quantitative. Le courant dominant des travaux universitaires en gestion a suivi les directives exposées dans ces livres. Malheureusement, ce type de sciences de gestion s'est également attiré de vigoureuses et larges critiques à l'égard de sa pertinence pratique. L'ouvrage de 1959 rejetait la tradition d'une gestion scientifique centrée sur la production – une tradition sur laquelle s'est fondée la construction rationalisée. Ainsi, le désaccord sous-jacent porte-t-il sur le rôle de la production dans la gestion: la production est-elle un point de départ pour la gestion ou se situe-t-elle en dehors de la gestion? Ce désaccord de fond est démontré à travers deux thèmes de recherche se situant au coeur du développement des sciences de gestion après 1959: la théorie organisationnelle, telle qu'elle a été élaborée par J.R. Galbraith, et l'économie des coûts de transaction, dont O. Williamson est l'initiateur. Sur la base des éléments probants apportés par les analyses faites, il est suggéré que le fait de ne pas avoir inclus la production dans la théorie a été l'une des causes principales de la situation problématique des sciences de gestion ces cinquante dernières années.

Mots clés: gestion de la construction?construction rationalisée?théorie du design organisationnel?économie des coûts de transaction?déchets     

不完全契约视角下PPP项目合作剩余分配的博弈分析

PPP作为一种典型的项目融资模式,为基础设施建设和公共物品服务提供了一种新的思路,解决了公共部门资金匮乏和运营效率低等问题,并在世界各国得到了广泛推广和应用。然而PPP因自身的项目特点使其契约具有不完全性,在公私合作双方达成初始契约后的合作协商阶段,初始契约中未明确规定的事项通过双方协商合作,可以获得初始契约中未涉及的合作剩余收益。针对该部分合作剩余收益,合作双方对分配份额进行谈判,考虑合作双方地位的非对称性以及信息不对称性,建立不完全信息动态博弈模型,求解精炼纳什均衡解,分析影响分配结果的因素,得出博弈方的信息类型对博弈结果影响最为显著,从而为PPP项目合作剩余分配谈判提供了有益参考。     

汶川地区地震后城市垃圾综合处理策略探讨

城市废墟清理和垃圾处理是地震后城市重建工作的首要内容。从地震灾害对汶川地区的影响出发,分析震后城市垃圾处理的特殊性,研究城市废墟中垃圾的来源分类与构成。在深入研究国内外城市震后垃圾处理经验的基础上.针对汶川地区自身特点,提出在灾后重建过程中垃圾处理的主要内容及综合处理策略,从而指导灾后的重建工作。