Carbonation of brine impacted fractionated coal fly ash: implications for CO2 sequestration

Coal combustion by-products such as fly ash (FA), brine and CO(2) from coal fired power plants have the potential to impact negatively on the environment. FA and brine can contaminate the soil, surface and ground water through leaching of toxic elements present in their matrices while CO(2) has been identified as a green house gas that contributes significantly towards the global warming effect. Reaction of CO(2) with FA/brine slurry can potentially provide a viable route for CO(2) sequestration via formation of mineral carbonates. Fractionated FA has varying amounts of CaO which not only increases the brine pH but can also be converted into an environmentally benign calcite. Carbonation efficiency of fractionated and brine impacted FA was investigated in this study. Controlled carbonation reactions were carried out in a reactor set-up to evaluate the effect of fractionation on the carbonation efficiency of FA. Chemical and mineralogical characteristics of fresh and carbonated ash were evaluated using XRF, SEM, and XRD. Brine effluents were characterized using ICP-MS and IC. A factorial experimental approach was employed in testing the variables. The 20-150 μm size fraction was observed to have the highest CO(2) sequestration potential of 71.84 kg of CO(2) per ton of FA while the >150 μm particles had the lowest potential of 36.47 kg of CO(2) per ton of FA. Carbonation using brine resulted in higher degree of calcite formation compared to the ultra-pure water carbonated residues.     

S-TE剩余污泥溶解过程中VSS的变化研究

从土壤中筛选出1株能分泌胞外酶、促进污泥溶解的嗜热脂肪芽孢杆菌Bacillus stearothermophilusAT07-1,将AT07-1培养液接种到不同浓度（TSS约为7.5、14.5、20.5 g/L）的剩余污泥中,于65℃进行嗜热菌溶解试验,并与未接种试验进行对比。结果表明,接种嗜热菌AT07-1促进了污泥中悬浮固体的溶解。60h时接种试验VSS的溶解率分别为61.41%、53.79%、41.86%,比不接种试验同期分别提高了27.57%、25.24%、16.26%。试验条件下VSS溶解过程在初始阶段（t=3d）符合一级反应动力学模型,接种后溶解速率常数Kd显著提高,从0.12 d-1、0.08 d-1、0.09 d^-1分别增加到0.27 d^-1、0.24 d^-1、0.13 d^-1。     

氮肥运筹和少免耕对麦田氮素径流流失的影响

采用田间小区定位试验研究了自然降雨条件下氮肥运筹和少免耕措施对稻麦两熟农田麦季氮素径流流失特征的影响。结果表明：自然降雨后麦田耕层土壤平均水分质量分数26.34%为径流事件发生的临界土壤水分质量分数。常规施肥（T0）条件下,麦季径流水量达2185.05 m3·hm-2,径流侵蚀泥沙量达716.08 kg.hm-2,少免耕（T2）处理增加麦田径流水量达29.67%,减少径流侵蚀泥沙量达13.96%,而肥料运筹（T1）与T0处理差异不显著;就整个麦季而言,T0处理条件下,径流水全氮（TN）平均质量浓度和径流侵蚀泥沙TN平均质量分数分别为10.51 mg·L-1和1.19 g·kg-1,T1处理显著降低径流水TN质量浓度和侵蚀泥沙TN质量分数分别达11.63%和5.93%,T2处理显著降低径流侵蚀泥沙TN质量分数达7.95%;麦季氮素径流流失主要集中在小麦生育前期,包括径流水氮素流失量和径流侵蚀过程中由泥沙流失的氮素量。T0处理条件下,氮素流失总量达31.76 kg·hm-2,其中,径流水氮素流失量占麦季氮素总流失量95%以上,T1处理减少麦季氮素总流失量达9.25%,而T2处理则增加麦季氮素总流失量达16.75%。     

Precipitation of Magnesium Carbonates as a Function of Temperature, Solution Composition, and Presence of a Silicate Mineral Substrate

Abstract Precipitation of carbonate minerals can play important roles in geological carbon sequestration and engineered processes for mineral carbonation. Influences of temperature, solution composition, and the presence of a solid substrate on the nucleation and precipitation of magnesium carbonate minerals were examined in a set of batch experiments. Conditions studied are relevant to full-scale geological carbon sequestration systems. Aqueous phase analysis by inductively coupled plasma mass spectrometry quantified the extent of precipitation. X-ray diffraction analysis was conducted to identify solids. Temperature significantly affected the identity of the solid obtained. At 25°C and 60°C the solids were magnesium carbonate minerals, and at 100°C the solid phase was identified as brucite [Mg(OH)2]. Although magnesite (MgCO3) was predicted to be the most thermodynamically stable magnesium carbonate phase, no magnesite precipitated and instead metastable magnesium carbonate phases formed. Evolution of d...     

Modeling of variations in nitrogen trichloride concentration over time in swimming pool water

In water, chlorine reacts with nitrogen-containing compounds to produce disinfection by-products such as nitrogen trichloride which induces ocular and respiratory irritations in swimming pool workers. This study proposes a model to predict variations in NCl₃ concentration over time in a traditional indoor swimming pool as a function of its operating parameters and attendance. The model was developed taking into consideration the reaction mechanisms, thermodynamic equilibria, physico-chemical properties, and transfer mechanisms occurring at the pool's surface. This model was validated through a robust series of experiments over two days and two nights in a real swimming pool. The model was found to satisfactorily predict variations over time in the concentrations of the chemical species investigated, including nitrogen trichloride. The work presented constitutes a first step to extend the model at different swimming pools. This approach may also be used to study the influence of the main operating parameters and to evaluate the impact of setting up water treatment systems on nitrogen trichloride concentration.     

丹东凤凰山山上与山下降水酸度迥异原因分析

采用分段监测的方法研究了辽宁丹东凤凰山垂直高度上的降水酸度及组分特征,并利用后向气流轨迹与分段离子相关性叠加分析的方法,对山上与山下降水酸度的差异成因进行了分析。结果表明：凤凰山4次降水中,pH值山上均低于山下,总离子浓度山上均低于山下,说明近地面大气污染物对酸雨起到一定的中和作用;山上降水酸度主要受大气远距离传输影响,山下降水酸度受本地源和远距离传输的共同作用。     

黄河北徙与北宋城市适应方式探析

黄河变迁史上的第三次大改道导致黄河突发北徙,彻底改变了泛滥区城市的自然和人文环境,是开展复杂人地耦合系统研究的理想区域。利用水平横剖面法、数理统计与GIS手段相结合的方法,探索黄泛城市的数目、时空变化特征和适应性类型。结果表明：（1）黄河7个行河期的决溢泛滥,产生29座受灾城市;（2）受灾城市总体分布广泛,但又相对集中分布在黄河决口所形成的洪积扇顶部附近,地势低洼的冀中平原以及黄、御等河流交汇处;（3）黄泛城市主要呈现出避河患迁城、因河患省并、原址加固防御、直接湮废四种适应性类型,以避河患迁城型居多,占45%;（4）朝廷政策和城市规模是影响城市在黄河突发灾害下的空间分异和适应性举措的重要人文因素。黄泛区受灾城市具有重要的地方性保存和可持续发展演进模式。建议将其纳入“黄河流域生态保护和高质量发展”国家战略,作为讲好黄河故事的重要区域。     

我国森林碳汇市场综述与展望

在对近几年相关研究文献进行梳理的基础上,试图厘清现阶段我国森林碳汇市场的研究现状,并追溯我国森林碳汇市场研究的发展脉络.主要从构建我国森林碳汇市场的必要性、可行性与意义,森林碳汇储量测量、森林碳汇市场运行模式与运行机制等方面进行评述,并提出进一步研究展望.认为未来研究应在创新整合森林碳汇储量测量方法,从政治、法律、制度、政策、环境与市场机制方面整体考虑提升我国森林碳汇市场的选择路径,从供需视角加强对市场交易主体的微观层面研究等方面突破.     

糠醛树脂防砂工艺在临盘油田的应用

针对临盘油田盘河区块地层砂粒细、泥质含量偏高,导致油井实施高压充填防砂后大面积堵塞、小井眼防砂措施有效率偏低两方面的问题,成功试验引进糠醛树脂防砂工艺。2010年初至2011年末,共在临盘油田试验22口井,有效率达86.3%,累计增油13 319.1t。该技术在临盘油田的成功应用,为同类油藏的防砂和开发提供了宝贵的经验和数据,具有重要的理论和实践意义。     

型式试验过程中机械振动试验方法的研究

本文以正弦振动为例,结合相应的国标指导,介绍了电工电子和(或)核仪器类产品进行型式试验过程中机械振动试验方法的研究,以考察产品能否经受住预定的振动条件,并根据经受试验不同严酷等级的能力来划分设备等级。