地下水LNAPL层的原位曝气模拟研究

曝气法(Air sparging,AS)已经成为修复地下水、土壤有机污染的重要技术,与数值模拟技术相结合可优化修复条件。文章利用TMVOC多相流模型研究了地下水位处LNAPL层的迁移转化,并通过情景模拟比较曝气法对污染修复的贡献率。只考虑地下水水流的对流-弥散作用时,目标污染物苯并没有得到彻底去除,只是通过下边界流出。60 d苯的质量损失率仅为1.79%;而连续曝气30 d后苯的去除率就可达到31.4%,最终脉冲曝气苯的损失率为44.8%。增大曝气量能提高气相渗透率及气相-液相接触面积,扩大污染物修复范围;当超过某一值(12 m3/h),其增量对污染物修复影响甚微。当曝气点位于低渗透岩层下方时,低渗透岩层会阻碍气流的垂向迁移,位于低渗透岩层上方的污染物很难得到除去。曝气法适用于溶解、挥发性较好的污染物。     

水蕴草对不同程度富营养化水体中氮磷去除能力的研究

通过静态模拟试验,研究了沉水植物水蕴草[Elodeadensa（Planch.）Casp.]对5种不同程度富营养化水体中氮、磷的去除能力。实验结果表明,水蕴草在5种不同程度富营养化水体中均能正常生长,且对水体中的氮、磷均表现出良好的净化效果。5种不同程度富营养化水体的TN、NO₃-N、NH₄-N、TP浓度分别由初始的3～36、2.25～27、1.2～9、1.2～14.4 mg/L降至0.29～6.82、0.3～5.8、0～1.035、0.022～5.51 mg/L。在模拟的不同营养浓度条件下,水蕴草对5种水体中TN、NO₃-N、NH₄-N、TP的累积去除率分别为:17%～28%、62%～88%、30%～70%、60%～100%。研究同时发现,水蕴草可以较好地净化不同程度的富营养化水体,并能保持清洁水体水质。     

五种挺水植物对矿山废水中锰的去除效能比较

以水葱、香蒲、芦苇、灯芯草和野茭白五种挺水植物为研究对象,通过实验室模拟人工湿地系统,研究在投加不同浓度梯度人工拟合酸性矿山废水条件下各植物对重金属锰的去除效能以及植物各部位对锰的富集能力。结果表明,野茭白和水葱的去除效能最显著,第七天的去除率达到90%和76%以上,香蒲的相对较差,为56%以上。五种植物各部位对重金属锰的富集能力均遵循同一规律:对于无茎植物,根富集浓度大于叶富集浓度;对于有茎植物,则为根大于茎大于叶。     

Technological Progress,Structural Change and China’s Energy Efficiency

Abstract

China has witnessed rapid economic development since 1978, and during the time, energy production and consumption developed at a tremendous speed as well. Energy efficiency which can be measured by energy consumption per unit of GDP, however, experienced continuous decrease. Theoretically, the change of energy efficiency can be attributed to industry structural change and technological change. In order to explain the transformation of Chinese energy efficiency, we adopt logarithmic mean Divisia index techniques to decompose changes in energy intensity in the period of 1994–2005. We find that technological change is the dominant contributor in the decline of energy intensity, but the contribution has declined since 2001. The change in industry structure has decreased the energy intensity before 1998, but raised the intensity after 1998. Decomposed technological effects for all sectors indicate that technological progresses in high energy consuming industries such as raw chemical materials and chemical products, smelting and pressing of ferrous metals, manufacture of non-metallic mineral products and household contribute are the principal drivers of China’s declining energy intensity.     

不同喷嘴类型静电旋风水膜除尘系统配置优化实验研究*

为对比加宽版吹风喷头、1 mm孔径广角实心喷嘴和组合型喷嘴配置下的静电旋风水膜除尘系统的除尘效果,对进口风速、静电电压和单位面积流量3个单因素进行实验。研究结果表明:借助SPSS软件正交实验设计得出各喷嘴最佳参数、除尘效率影响因素排序均为进口风速＞静电电压＞单位面积流量。在各喷嘴最佳参数下,除尘性能排序为组合型喷嘴>加宽版吹风喷头>1 mm孔径广角实心喷嘴。在组合型喷嘴最佳参数（进口风速12.03 m/s、单位面积流量1.02 L/(m2·s)、电压45 kV）下,当进口风速不变时,除尘系统的分级除尘效率随粉尘颗粒粒径的增大而增大,但增幅不断地变缓,粒径约为40 μm时分级效率近似达到100%;当粉尘颗粒粒径不变时,分级效率随进口风速的增大呈现递减的趋势,粒径越大下的分级效率越接近。     

Heat loss analysis: An approach toward the revival of parabolic dish type solar cooker

Present work investigates a noble approach toward the heat loss analysis of parabolic dish type solar cooker. Various experiments have been done on cooking pot to get the input parameter for calculation purposes. Cooking pot was kept at the focus of a parabolic dish type concentrator and repeated experiments have been done to measure solar radiation intensity (direct and Indirect) using a pyrometer, temperature at the focus of parabolic dish using a thermocouple and air velocity using hot wire anemometer to investigate the heat losses from the cooking pot. In the present article, a numerical approach has been performed to define the new parameter called performance index of the cooking pot which decides how the useful energy of working fluid inside the cooking pot approaches concentration ratio of the parabolic dish type solar cooker. The present analysis shows that the performance index varies from 15.45 to 17.66 and efficiency varies from 85.83% to 98.10% with the time of the day.     

铁炭曝气微电解对炸药废水的试验研究

采用铁炭曝气微电解对炸药废水进行预处理,处理结果表明:当炸药废水调节pH值为2,反应时间2h,物质A投加量2g/L,铁屑与活性炭体积比为1∶1时,进水TOC为2600mg/L,COD为2500mg/L,NH3-N为190mg/L,出水TOC为250mg/L,COD为400mg/L,NH3-N为20mg/L,去除率分别为90.5%、82%和89.6%,BOD5/COD由0.16提高到0.38。     

缓释肥侧条施肥技术对水稻产量和氮素利用效率的影响

利用田间小区试验,系统研究了基于缓释肥料的侧条施肥技术对水稻产量和氮素利用效率的影响。试验结果表明：与农民常规施肥处理（FP）比较,侧条施肥技术高缓释肥处理（HF）水稻氮素投入比农民常规施肥处理（FP）降低约40%,水稻产量没有显著降低,穗粒数比农民常规施肥处理增加了8.36%。侧条施肥技术显著提高了水稻地上部吸氮量和氮肥偏生产力,降低了氮素的表观损失量。侧条施肥各处理氮肥偏生产力在39.1～67.8之间,显著高于FP处理的23.7。FP处理氮素表观损失量高达174.2 kg＆#183;hm-2,侧条施肥各处理表观损失量在23.2～61.9 kg＆#183;hm-2之间。综合考虑水稻产量和环境因素,基于缓释肥料的侧条施肥技术是一种资源节约和环境友好的施肥技术。     

基于DEA-Malmquist指数的辽宁省城市建设用地配置效率研究

从提高城市建设用地配置效率角度出发,运用DEA-Malmquist指数模型,通过选择投入产出要素对辽宁省2006-2012年城市建设用地全要素生产率进行分析,对全省及各市城市建设用地配置效率的变化和技术效率、技术进步对城市建设用地配置效率的影响做出评价.研究表明,研究期内各城市全要素生产率处于小幅增长态势,平均增长率为1.1％,纯技术效率呈波动性增减,表明各城市尚未充分利用先进技术和资源优化配置,规模效率普遍偏低,平均值为0.996＜1,未向最优规模靠近,技术进步对全要素生产率变化指数的增长贡献率不高.