Thermal and hydrometallurgical recovery methods of heavy metals from municipal solid waste fly ash

Heavy metals in fly ash from municipal solid waste incinerators are present in high concentrations. Therefore fly ash must be treated as a hazardous material. On the other hand, it may be a potential source of heavy metals. Zinc, lead, cadmium, and copper can be relatively easily removed during the thermal treatment of fly ash, e.g. in the form of chlorides. In return, wet extraction methods could provide promising results for these elements including chromium and nickel. The aim of this study was to investigate and compare thermal and hydrometallurgical treatment of municipal solid waste fly ash. Thermal treatment of fly ash was performed in a rotary reactor at temperatures between 950 and 1050 °C and in a muffle oven at temperatures from 500 to 1200 °C. The removal more than 90% was reached by easy volatile heavy metals such as cadmium and lead and also by copper, however at higher temperature in the muffle oven. The alkaline (sodium hydroxide) and acid (sulphuric acid) leaching of the fly ash was carried out while the influence of temperature, time, concentration, and liquid/solid ratio were investigated. The combination of alkaline-acidic leaching enhanced the removal of, namely, zinc, chromium and nickel.     

Emissions associated with meeting the future global wheat demand: A case study of UK production under climate change constraints

Climate change, population growth and socio-structural changes will make meeting future food demands extremely challenging. As wheat is a globally traded food commodity central to the food security of many nations, this paper uses it as an example to explore the impact of climate change on global food supply and quantify the resulting greenhouse gas emissions. Published data on projected wheat production is used to analyse how global production can be increased to match projected demand. The results show that the largest projected wheat demand increases are in areas most likely to suffer severe climate change impacts, but that global demand could be met if northern hemisphere producers exploit climate change benefits to increase production and narrow their yield gaps. Life cycle assessment of different climate change scenarios shows that in the case of one of the most important wheat producers (the UK) it may be possible to improve yields with an increase of only 0.6% in the emission intensity per unit of wheat produced in a 2 °C scenario. However, UK production would need to rise substantially, increasing total UK wheat production emissions by 26%. This demonstrates how national emission inventories and associated targets do not incentivise minimisation of global greenhouse gas emissions while meeting increased food demands, highlighting a triad of challenges: meeting the rising demand for food, adapting to climate change and reducing emissions.     

BOD_5样品分析中稀释倍数的确定探讨

首先正确估计出样品ＢＯＤ５浓度范围，并测定稀释水的溶解氧，然后根据稀释倍数公式计算出三个适当的稀释倍数，与其它方法相比，本方法省时、可靠、适用性强、能够确保ＢＯＤ５样品分析一次成功，在ＢＯＤ５样品分析中具有广泛的应用价值．     

城市老工业区土壤重金属污染状况与健康风险评价

本文对西部某老工业区土壤中As、Pb、Cr、Cd、Hg、Zn的含量、空间分布状况展开了研究,并依据《污染场地风险评估技术导则》对该老工业区的健康风险进行了评价。研究结果表明,该老工业区土壤重金属污染严重,6种元素与陕西土壤背景值相比超标100%,表明其不适宜作为居住用地开发。健康风险评价结果显示,As、Pb、Cr、Cd元素的非致癌风险值分别为3.83、1.7、1.94、1.09,均超过非致癌风险可接受值1,表明该老工业区对人们存在非致癌健康风险;对于致癌风险,As、Cr、Cd元素的致癌风险值远大于致癌风险边界值,分别超过致癌风险值的2个数量级(2.64×10-4)、4个数量级(1.94×10-2)、1个数量级(6.12×10-5),表示As和Cr已经达到了显著致癌风险的水平。     

Using Sound to Reduce Visual Distraction from In-vehicle Human–Machine Interfaces

Objective: Driver distraction and inattention are the main causes of accidents. The fact that devices such as navigation displays and media players are part of the distraction problem has led to the formulation of guidelines advocating various means for minimizing the visual distraction from such interfaces. However, although design guidelines and recommendations are followed, certain interface interactions, such as menu browsing, still require off-road visual attention that increases crash risk. In this article, we investigate whether adding sound to an in-vehicle user interface can provide the support necessary to create a significant reduction in glances toward a visual display when browsing menus.

Methods: Two sound concepts were developed and studied; spearcons (time-compressed speech sounds) and earcons (musical sounds). A simulator study was conducted in which 14 participants between the ages of 36 and 59 took part. Participants performed 6 different interface tasks while driving along a highway route. A 3 × 6 within-group factorial design was employed with sound (no sound /earcons/spearcons) and task (6 different task types) as factors. Eye glances and corresponding measures were recorded using a head-mounted eye tracker. Participants’ self-assessed driving performance was also collected after each task with a 10-point scale ranging from 1 = very bad to 10 = very good. Separate analyses of variance (ANOVAs) were conducted for different eye glance measures and self-rated driving performance.

Results: It was found that the added spearcon sounds significantly reduced total glance time as well as number of glances while retaining task time as compared to the baseline (= no sound) condition (total glance time M = 4.15 for spearcons vs. M = 7.56 for baseline, p =.03). The earcon sounds did not result in such distraction-reducing effects. Furthermore, participants ratings of their driving performance were statistically significantly higher in the spearcon conditions compared to the baseline and earcon conditions (M = 7.08 vs. M = 6.05 and M = 5.99 respectively, p =.035 and p =.002).

Conclusions: The spearcon sounds seem to efficiently reduce visual distraction, whereas the earcon sounds did not reduce distraction measures or increase subjective driving performance. An aspect that must be further investigated is how well spearcons and other types of auditory displays are accepted by drivers in general and how they work in real traffic.     

Numerical simulation of premixed methane–air deflagration in a semi-confined obstructed chamber

In this paper, large eddy simulation coupled with a turbulent flame speed cloure (TFC) subgrid combustion model has been utilized to simulate premixed methane–air deflagration in a semi-confined chamber with three obstacles mounted inside.The computational results are in good agreement with published experimental data, including flame structures, pressure time history and flame speed. The attention is focused on the flame flow field interaction, pressure dynamics, as well as the mechanism of obstacle-induced deflagration. It is found that there is a positive feedback mechanism established between the flame propagation and the flow field. The pressure time history can be divided into four stages and the pseudo-combustion concept is proposed to explain the pressure oscillation phenomenon. The obstacle-induction mechanism includes direct effect and indirect effect, but do not always occur at the same time.     

The Effect of Local Biomass Projects on Energy Balance and GHG Emission: A Life Cycle Approach

Emerging attention has been given to the use of biomass in local areas for its contribution to reducing fossil fuel dependence and mitigating global warming. The objective of the present study is to develop a method that quantitatively assesses the effects of local biomass projects on fossil fuel consumption and greenhouse gas (GHG) emission. A practical method based on a life cycle approach is proposed and applied to a case of bioethanol project in Miyako Islands of Japan. The project is aiming to produce bioethanol from molasses within the islands, and to replace the entire gasoline consumed in the islands to E3 fuel (i.e., a mixture of 3% ethanol and 97% gasoline by volume). The assessment using the developed method revealed that, first, the complete shift from gasoline to E3 fuel allows for decreases in fossil fuel consumption and GHG emission. Second, the performance of the project is improved by the integration of the ethanol plant and the sugar factory. Moreover, the assessment found that, in small-scale bioethanol projects, the contribution of capital goods to life cycle fuel consumption and GHG emission is not negligible.     

德兴铜矿不同年份废石产酸规律研究

矿山选矿废石、尾矿在长期堆积过程中氧化产生的酸性废水会对环境造成严重危害.实验选取德兴铜矿1、5、10和20年废石进行产酸规律研究,静态评价结果显示,4种废石均有产酸潜势,且除1年废石以外均已产酸.为期9个月的动态评价结果表明,4个年份的废石pH均与电导率呈显著负相关,检出离子主要为氟化物、Cu2+、Zn2+、SO2-4、Fe3+.1年废石在整个实验进行中并未产酸,5、10年废石产酸稳定,20年废石产酸缓慢,可推断废石的产酸过程为:不产酸-高速产酸-稳定产酸-产酸速率下降.     

Interspecific and intraspecific identification of Dendrobium based on the psbAtrnH intergenic region sequences and the 5S rRNA gene spacer sequences北大核心CSCD

This research aimed to investigate the interspecific and intraspecific identification of Dendrobium by using the multi-locus method so as to provide a molecular basis for Dendrobium identification through the combination of chloroplast psbA-trnH intergenic region sequences and ribosome 5S rRNA gene spacer sequences. PCR direct sequencing was applied to detect the chloroplast psbA-trnH intergenic region sequences as well as the ribosome 5S rRNA gene spacer sequences of 12 Dendrobium species, while the psbA-trnH intergenic region sequences of Dendrobium denneanum dq-2 variety and dq- 5line were cloned and sequenced for single nucleotide polymorphism (SNP) analyzing. The sequences were analyzed by the software Sequencher4.14, Bioedit7.0, MEGA5.2 and Dansp5.0; the interspecific and intraspecific Kimara-2-Parameter(K2P) distances were also calculated. The phylogenetic tree (using Neighbor joining method) was constructed with Bulbophyllum odoratissimum and Bletilla striata as outgroup. The results showed an average length of chloroplast psbA-trnH gene sequences in Dendrobium as 742.3 bp, with 72 variable sites, including 33 information sites; the average length of the ribosome 5S rRNA gene spacer sequences in Dendrobium was 336.4 bp, with 213 variable sites including 139 information sites. Using psbAtrnH intergenic region sequences in combination with ribosome 5S rRNA gene spacer sequences can not only identify D. denneanum, D. hancockil, D. thysiflorum, D. devonianum, D. moniliforme, D. chrysotoxum, D. officinale, D. heterocarpum and D. nobile, but also differentiate D. officinale from different geographical populations, and distinguish the dq-2 variety and dq 5line with SNP in the multi locus of D. denneanum.     

Application of an odd/even predominance of n-alkanes in oil–source rock correlation: taking the lower Paleozoic strata of the Tarim Basin as an example

The composition and distribution of n-alkanes carbon numbers reflect the source of kerogenic organic matter, sedimentary environment, and maturity of the rocks. The comparison results of the n-alkanes GC (gas chromatography) chromatograms in the Tazhong Low Uplift show that the n-alkanes of the source rocks in Upper Ordovician display an odd carbon number predominance. At the same time, Cambrian–Lower Ordovician exhibit an even carbon number predominance. The correlation between oil and source rock illustrates that crude oils in the fields of well TZ10-12 and well TZ24 stem from the Upper Ordovician source rocks. The origins of the crude oils in the fields of well TZ161-162 and well TZ45 are Cambrian–Lower Ordovician. The strata corresponding to the crude oils with odd/even carbon number predominance match the oil–source rock correlation. Thus, the characteristics of odd/even carbon number predominance in n-alkane compounds are effective for oil–source rock correlation in the Tazhong Low Uplift, Tarim Basin.