Dimensionality of heavy metal distribution in waste disposal sites using nonlinear dynamics

Mapping of heavy metal contamination in mining and waste disposal sites usually relies on geostatistical approaches and linear stochastic dynamics. The present paper aims to identify, using the Grassberger-Procaccia correlation dimension (CD) algorithm, the existence of a nonlinear deterministic and chaotic dynamic behaviour in the spatial pattern of arsenic, manganese and zinc concentration in a Russian coal waste disposal site. The analysis carried out yielded embedding dimension values ranging between 7 and 8 suggesting thus from a chaotic dynamic perspective that arsenic, manganese and zinc concentration in space is a medium dimensional problem for the regionalized scale considered in this study. This alternative nonlinear dynamics approach may complement conventional geostatistical studies and may be also used for the estimation of risk and the subsequent screening and selection of a feasible remediation scheme in wider mining and waste disposal sites. Finally, the synergistic effect of this study may be further elaborated if additional factors including among others presence of hot spots, density and depth of sampling, mineralogy of wastes and sensitivity of analytical techniques are taken into account.     

Biosphere models in radioactive waste disposal assessment

This paper briefly discusses the uncertainties associated with predictions made using biosphere models in assessments of radioactive waste repositories. Typical models, processes influencing transport and accumulation of radionuclides and the subsequent pathways evaluation are described. Reducible and non-reducible uncertainties are presented as well as some conclusions about the predictive power of the models.     

Risk management and the landfill in hazardous waste disposal

Amidst the current dialogue surrounding drives at state and federal levels to ban the use of landfills for certain hazardous wastes, it is easy to lose     

Treatment of waste printed wire boards in electronic waste for safe disposal

The printed wire boards (PWBs) in electronic waste (E-waste) have been found to contain large amounts of toxic substances. Studies have concluded that the waste PWBs are hazardous wastes because they fails the toxicity characteristic leaching procedure (TCLP) test with high level of lead (Pb) leaching out. In this study, two treatment methods - high-pressure compaction and cement solidification - were explored for rendering the PWBs into non-hazardous forms so that they may be safely disposed or used. The high-pressure compaction method could turn the PWBs into high-density compacts with significant volume reduction, but the impact resistance of the compacts was too low to keep them intact in the environment for a long run. In contrast, the cement solidification could turn the PWBs into strong monoliths with high impact resistance and relatively high compressive strength. The leaching of the toxic heavy metal Pb from the solidified samples was evaluated by both a dynamic leaching test and the TCLP test. The dynamic leaching results revealed that Pb could be effectively confined in the solidified products under very harsh environmental conditions. The TCLP test results showed that the leaching level of Pb was far below the regulatory level of 5mg/L, suggesting that the solidified PWBs are no longer hazardous. It was concluded that the cement solidification is an effective way to render the waste PWBs into environmentally benign forms so that they can be disposed of as ordinary solid wastes or beneficially used in the place of concrete in some applications.     

浅谈印铁设备的管理

设备管理既是企业生产组织结构的基础,又是企业正常生产经营的保障,其管理水平的高低不仅直接影响企业的产品质量和生产效益,而且还关系着企业的外在形象和市场竞争实力.印铁生产线一般都比较昂贵,如何最大可能地延长其使用寿命和使用效率,成为印铁企业设备管理的关键.本文结合本厂的实际情况,主要谈谈在不增加企业成本的基础上,如何调动人的积极性和主动性,将人和机器有机地结合起来,最大限度地提高设备的开机率?     

Understanding environmental impacts on initial atmospheric corrosion based on corrosion monitoring sensors

Atmospheric corrosion monitoring(ACM)sensors were employed to study the initial atmospheric corrosion of carbon steels over a one-month period in six outdoor dynamic atmospheric environments in China.Based on the~250,000 corrosion data sets collected,the environmental impacts of relative humidity,temperature and rainfall on the initial corrosion behavior of carbon steels were investigated.The results showed that rainfall was the strongest environmental factor influencing the initial atmospheric corrosion rate.Relative humidity significantly influenced the corrosion of carbon steels in low-precipitation environments and non-rainfall period.     

Review of the atmospheric corrosion of magnesium alloys

Mg atmospheric corrosion is induced by a thin surface aqueous layer. Controlling factors are microgalvanic acceleration between different phases, protection by a continuous second phase distribution, protection by corrosion products, and degradation of protective layers by aggressive species such as chloride ions. The Mg atmospheric corrosion rate increases with relative humidity (RH) and concentrations of aggressive species. Temperature increases the corrosion rate unless a protective film causes a decrease. O₂, SO₂ and NO₂ accelerate the atmospheric corrosion rate, whereas the corrosion rate is decreased by CO₂. The traditional gravimetric method can evaluate effectively the corrosion behavior of Mg alloys.     

Evolution of corrosion products and metal release from Galvalume coatings on steel during short and long-term atmospheric exposures

Non-treated Galvalume (55% Al, 43.4% Zn and 1.6% Si by weight) coatings have been studied through a combination of surface, near surface and bulk analysis after exposure at marine conditions, and for comparison also in an urban test site and in successively more complex short-term laboratory exposures. Slightly polished Galvalume surfaces exhibit dendritic aluminum-rich areas with higher Volta potential compared with interdendritic zinc-rich areas. These effects were not observed on bare as-received surfaces due to the overall presence of aluminum oxide. As a result, preferential corrosion occurred initially in interdendritic areas. The zinc release rate followed the same time-dependence as the surface coverage of zinc-containing phases at the marine exposure condition with zinc predominantly released compared to aluminum. Short term laboratory exposures generated the same main phases as formed at marine conditions. This confirms that the evolution of corrosion products and time dependence of zinc release rates can be explained by the uniform formation of less soluble Al₂O₃, AlOOH and Al(OH)₃ compared to observed zinc-containing phases, e.g. ZnO, zinc hydroxycarbonate and zinc hydroxychloride. The same underlying mechanism is believed to operate also during exposure of Galvalume in the urban site studied.     

Review on modelling of corrosion under droplet electrolyte for predicting atmospheric corrosion rate

Atmospheric corrosion of metals is the most common type of corrosion which has a significant impact on the environment and operational safety in various situations of everyday life.Some of the common examples can be observed in land,water and air transportation systems,electronic circuit boards,urban and offshore infrastructures.The dew drops formed on metal surface due to condensation of atmospheric moisture facilitates corrosion as an electrolyte.The corrosion mechanisms under these droplets are different from classically known bulk electrolyte corrosion.Due to thin and non-uniform geometric thickness of the droplet electrolyte,the atmospheric oxygen requires a shorter diffusion path to reach the metal surface.The corrosion under a droplet is driven by the depletion of oxygen in the center of the droplet compared to the edge,known as differential aeration.In case of a larger droplet,differential aeration leads to preferential cathodic activity at the edge and is controlled by the droplet geometry.Whereas,for a smaller droplet,the oxygen concentration remains uniform and hence cathodic activity is not controlled by droplet geometry.The geometry of condensed droplets varies dynamically with changing environmental parameters,influencing corrosion mechanisms as the droplets evolve in size.In this review,various modelling approaches used to simulate the corrosion under droplet electrolytes are presented.In the efforts of developing a comprehensive model to estimate corrosion rates,it has been noted from this review that the influence of geometric evolution of the droplet due to condensation/evaporation processes on corrosion mechanisms are yet to be modelled.Dynamically varying external factors like environmental temperature,relative humidity,presence of hygroscopic salts and pollutants influence the evolution of droplet electrolyte,making it a complex phenomenon to investigate.Therefore,an overview of available dropwise condensation and evaporation models which describes the formation and the evolution of droplet geometry are also presented from an atmo s pheric corrosion viewpoint.     

Introduction to atmospheric corrosion research in China

In this paper, we introduce the research on atmospheric corrosion in China. We describe the climate characteristics and the classification of atmospheric corrosivity across the whole country. We also describe the rusting evolution under simulated wet/dry cyclic conditions.     

Introduction to atmospheric corrosion research in China

In this paper, we introduce the research on atmospheric corrosion in China. We describe the climate characteristics and the classification of atmospheric corrosivity across the whole country. We also describe the rusting evolution under simulated wet/dry cyclic conditions.     

A conflict model for the international hazardous waste disposal dispute

A multi-stage conflict model is developed to analyze international hazardous waste disposal disputes. More specifically, the ongoing toxic waste conflicts are divided into two stages consisting of the dumping prevention and dispute resolution stages. The modeling and analyses, based on the methodology of graph model for conflict resolution (GMCR), are used in both stages in order to grasp the structure and implications of a given conflict from a strategic viewpoint. Furthermore, a specific case study is investigated for the Ivory Coast hazardous waste conflict. In addition to the stability analysis, sensitivity and attitude analyses are conducted to capture various strategic features of this type of complicated dispute.     

Leaching of CCA-treated wood: implications for waste disposal

Leaching of arsenic, chromium, and copper from chromated copper arsenate (CCA)-treated wood poses possible environmental risk when disposed. Samples of un-weathered CCA-treated wood were tested using a variety of the US regulatory leaching procedures, including the toxicity characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), extraction procedure toxicity method (EPTOX), waste extraction test (WET), multiple extraction procedure (MEP), and modifications of these procedures which utilized actual MSW landfill leachates, a construction and demolition (C and D) debris leachate, and a concrete enhanced leachate. Additional experiments were conducted to assess factors affecting leaching, such as particle size, pH, and leaching contact time. Results from the regulatory leaching tests provided similar results with the exception of the WET, which extracted greater quantities of metals. Experiments conducted using actual MSW leachate, C and D debris leachate, and concrete enhanced leachate provided results that were within the same order of magnitude as results obtained from TCLP, SPLP, and EPTOX. Eleven of 13 samples of CCA-treated dimensional lumber exceeded the US EPA's toxicity characteristic (TC) threshold for arsenic (5 mg/L). If un-weathered arsenic-treated wood were not otherwise excluded from the definition of hazardous waste, it frequently would require management as such. When extracted with simulated rainwater (SPLP), 9 of the 13 samples leached arsenic at concentrations above 5 mg/L. Metal leachability tended to increase with decreasing particle size and at pH extremes. All three metals leached above the drinking water standards thus possibly posing a potential risk to groundwater. Arsenic is a major concern from a disposal point of view with respect to ground water quality.     

竹材废弃物作为工业锅炉燃料的研究

我国竹材资源在传统制作和工业加工过程中的重量利用率低于40%,有60%以上的竹材成为加工剩余物,竹材生物资源量巨大.竹材的硫和灰分含量仅为洁净煤质燃料的1/5~1/3,是一种非常洁净的燃料.竹材作为工业锅炉燃料时,含水量应控制在20%以下.燃煤锅炉改烧竹材燃料时,需对配风方案、进料机构和局部结构进行改进.竹材废弃物代油燃烧,具有明显的价格优势和环保效益.经济性分析结果表明,在竹材废弃物丰富的地区,开发燃用竹材废弃物的工业锅炉具有良好的经济性.     

In-bed corrosion of alloys in atmospheric fluidized bed combustors

A series of tests, each of 250 h duration, which is designed to examine the effect of changes in operational parameters on in-bed corrosion, is in progress using a 0.3 m-square atmospheric fluidized bed combustor (AFBC). A 2000-h test has been conducted on a 1.1 mdiameter AFBC, partly to determine the comparability between the results of the tests in the small unit and those in more realistically sized beds, and partly to assess the performance of candidate materials of construction in a longer-term test. The results indicatethat the smaller unit is indeed a satisfactory representation of large AFBCs. Variables such as coal type, coal sulphur content, acceptor type, excess combustion air and bed temperature appear to have relatively little effect on in-bed oxidation/ sulphidation corrosion, certainly within the limits likely in normal operation. Several materials which appear to be suitable for construction of a fluidized bed boiler are identified, although it is emphasized that extrapolation of short-term tests is particularly dangerous for this form of corrosion.     

Distribution of corrosion pits on a metal surface

The distribution of corrosion pits on the surface of stainless steel samples treated in a 3% NaCl solution is studied. It is established that the distributions are thermodynamically optimized and can be described by the Gibbs expression for a canonical distribution of the thermodynamic probability of energy fluctuations. A wide occurrence of the pitting corrosion and the broad scatter of pits with respect to size are explained.     

Geostatistical risk estimation at waste disposal sites in the presence of hot spots

The present paper aims to estimate risk by using geostatistics at the wider coal mining/waste disposal site of Belkovskaya, Tula region, in Russia. In this area the presence of hot spots causes a spatial trend in the mean value of the random field and a non-Gaussian data distribution. Prior to application of geostatistics, subtraction of trend and appropriate smoothing and transformation of the data into a Gaussian form were carried out; risk maps were then generated for the wider study area in order to assess the probability of exceeding risk thresholds. Finally, the present paper discusses the need for homogenization of soil risk thresholds regarding hazardous elements that will enhance reliability of risk estimation and enable application of appropriate rehabilitation actions in contaminated areas.