SNCR脱硝技术在循环流化床中的应用

利用CFD进行数学建模,分析了某厂220 t/h CFB锅炉的温度及流场分布情况。在此基础上,针对性的设计开发了满足工艺要求的喷枪并对喷射位置进行了优化,模拟了还原剂与烟气混合情况,确定了工程设计参数。工程测试结果表明,系统脱硝效率及氨逃逸率均达到设计要求,其中脱硝效率最高可超过75%。     

Screening the emission sources of volatile organic compounds (VOCs) in China by multi-effects evaluation

We develop a multi-effect evaluation method to assess integrated impact of VOCs. Enable policy-makers to identify important emission sources, regions, and key species. Solvent usage and industrial process are the most important anthropogenic sources. Styrene, toluene, ethylene, benzene, and m/p-xylene are key species to be cut. Volatile organic compounds (VOCs) play important roles in the atmosphere via three main pathways: photochemical ozone formation, secondary organic aerosol production, and direct toxicity to humans. Few studies have integrated these effects to prioritize control measures for VOCs sources. In this study, we developed a multi-effects evaluation methodology based on updated emission inventories and source profiles, by combining the ozone formation potential (OFP), secondary organic aerosol potential (SOAP), and VOC toxicity data. We derived species-specific emission inventories for 152 sources. The OFPs, SOAPs, and toxicity of each source were estimated, the contribution and sharing of source to each of these adverse effects were calculated. Weightings were given to the three adverse effects by expert scoring, and then the integrated effect was determined. Taking 2012 as the base year, solvent use and industrial process were found to be the most important anthropogenic sources, accounting for 24.2% and 23.1% of the integrated effect, respectively, followed by biomass burning, transportation, and fossil fuel combustion, each had a similar contribution ranging from 16.7% to 18.6%. The top five industrial sources, including plastic products, rubber products, chemical fiber products, the chemical industry, and oil refining, accounted for nearly 70.0% of industrial emissions. Beijing, Chongqing, Shanghai, Jiangsu, and Guangdong were the five provinces contributing the largest integrated effects. For the VOC species from emissions showed the largest contributions were styrene, toluene, ethylene, benzene, and m/p-xylene.     

保守性离子在包气带层状土中运移规律研究

为研究溶质在多层层状包气带土中运移规律,选取5种颗粒配比不同的土样填装成由粗及细和由细及粗两分层顺序相反的土柱,通过室内试验研究保守性Br-在两种不同结构层状土中基本运移规律。研究得出:当土体表层遭受浓度为200 g/L Na Br一次性污染,在15 mm/12 h降雨强度下,Br-在第1、2层土体浓度经历快速上升段、峰值段、下降段3个阶段变化,第3、4、5层土体浓度经历上升段、平稳下降段。试验结束时,Br-在由粗及细的土柱中分布较均匀,在由细及粗的土柱中集中在表层;溶质穿透整个土柱的时间,由粗及细结构比由细及粗结构提前96 h。结果表明,在截污性能和延缓溶质向地下水补给方面,由细及粗结构均要优于由粗及细的结构。     

混凝-Fenton法预处理模拟电脱盐废水

采用混凝-Fenton法对模拟电脱盐废水进行预处理,筛选出最佳混凝和氧化条件。结果表明:FeSO4.7H2O和聚丙烯酰胺投加量分别为1000 mg/L和7 mg/L,Fenton反应初始pH值为7,H2O2投加量为0.06 mL/mL(分两次投加),n(H2O2)∶n(Fe2+)=10∶1,反应2 h的条件下,经此法处理后硫化物和COD去除率分别达99%和90%以上,废水中较低浓度的Fe3+和Mn2+有利于Fenton氧化反应。     

Effect of technology development on potential environmental impacts from heavy metals in waste smartphones

Technology development has brought beneficial changes in the functions of smartphones but has the potential to impact the environment due to the high generation of waste smartphones. Thus, this study evaluates and compares environmental impact potentials from metals in waste smartphones to figure out the effect of smartphone model replacements on hazardous waste, resource depletion, and toxicity potentials. The total threshold limit concentration (TTLC) analysis is used to determine whether the waste smartphones would be classified as hazardous waste, and the life-cycle impact assessment methods are used to evaluate resource depletion, cancer, non-cancer, and ecotoxicity potentials. The TTLC results showed that the smartphone technology development did not reduce hazardous waste potentials. The life-cycle impact assessment results showed that the technology development overall reduced resource depletion potential but increased toxicity potential. In addition, priority metals contributing to the potentials were identified to effectively manage their environmental impacts. This study can provide fundamental information for smartphone manufacturers, waste smartphone recyclers and disposers, and e-waste policymakers to circulate resources and to prevent environmental pollutions from hazardous and toxic materials.     

噪声背景值修正问题研究

为了解和掌握环境背景噪声对边界噪声监测结果的影响情况,本文就此作了相应的探讨。结果显示：当测量值与背景值的差值超过10dB（A）时,可以忽略背景值对测量结果的影响;当测量值与背景值的差值为3～10dB（A）时,应分段考虑背景值的修正;当测量值与背景值的差值小于3dB（A）时,应重新选择时间进行测定。     

Effects of iodoacetic acid drinking water disinfection byproduct on the gut microbiota and its metabolism in rats

Iodoacetic acid(IAA) is an unregulated disinfection byproduct in drinking water and has been shown to exert cytotoxicity, genotoxicity, tumorigenicity, and reproductive and developmental toxicity. However, the effects of IAA on gut microbiota and its metabolism are still unknown, especially the association between gut microbiota and the metabolism and toxicity of IAA. In this study, female and male Sprague–Dawley rats were exposed to IAA at 0 and 16 mg/kg bw/day daily for 8 weeks by oral gavage....     

Potential of different species for use in removal of DDT from the contaminated soils

Dichlorodiphenyltrichloroethane (DDT) and its main metabolites, p,p'-DDD and p,p'-DDE (DDTs in this study included DDT, DDD and DDE), are frequently detected in agricultural soils even though its usage in agriculture was banned in 1980s or earlier. In this study, eleven plants including eight maize (Zea mays) cultivars and three forage species (alfalfa, ryegrass and teosinte) widely cultivated in China were grown in the soils spiked with DDTs to investigate their potential for removal of DDT from the contaminated soils. The plants varied largely in their ability to accumulate and translocate DDTs, with the bioconcentration factor (BCF; DDT concentration ratio of the plant tissues to the soils) ranging from 0.014 to 0.25 and the translocation factor (TF; DDT concentration ratio of the shoots to the roots) varying from 0.35 (Zea mays cv Chaotian-23) to 0.76 (Zea mays spp. mexicana). The amount of DDT phytoextraction ranged from 3.89mug (ryegrass) to 27.0mug (teosinte) and accounted for <0.1% of the total initial DDTs spiked in the soils. After 70d, the removal rates reached 47.1-70.3% of the total initial DDTs spiked in the soils with plants while that was only 15.4% in the soils without plant. Moreover, the higher removal rates of DDTs occurred at the first 20d of experiment, and then the removal rate decreased with time. The highest amount of DDTs phytoextracted was observed in teosinte, followed by Zea mays spp. mexicana, but the highest removal rate of DDTs was found in maize (Zea mays cv Jinhai-6). Even though phytoextraction is not the main removal process for DDTs, the plant species especially Zea mays cv Jinhai-6 showed high potential for removing DDTs from the contaminated soils.     

Symmetrizing cathode-anode response to speed up charging of nanoporous supercapacitors

Asymmetric behaviors of capacitance and charging dynamics in the cathode and anode are general for nanoporous supercapacitors. Understanding this behavior is essential for the optimal design of supercapacitors. Herein, we perform constant-potential molecular dynamics simulations to reveal asymmetric features of porous supercapacitors and their effects on capacitance and charging dynamics. Our simulations show that, counterintuitively, charging dynamics can be fast in pores providing slow ion dif...     

中国排污权有偿使用定价及政策影响研究

排放配额的价格是排污权有偿使用政策的关键要素之一。本研究从分析排污权有偿使用政策的内涵出发,厘清有偿使用政策与已有排污收费政策的区别,排污收费是企业为污染物排放造成对环境损害而支付的补偿,而有偿使用费是企业为污染物排放占用环境容量资源支付的稀缺租金。本研究同时考虑了现行排污收费政策和总量控制政策的影响,基于最优化控制理论建立了COD和NH_3-N两种水污染物为独立变量的价格模型,并对有偿使用政策执行后可能带来的影响进行了模拟预测。