除尘风机工况调节的实践

对常用的几种风机工况点调节方法进行了概述,并结合自身的实践论述了它的优点和缺点。     

石灰石沟-堆肥湿地系统处理酸性矿山废水的研究

为探讨石灰石沟-潜流堆肥湿地系统处理酸性矿山废水(AMD)的效果及影响因素,进行了6个月模拟试验,测定出水水质和植物生长等相关的影响因素.结果表明,石灰石沟可有效提高AMD的pH值,降低其酸度与重金属含量,但随着石灰石沟中氢氧化物的积累,后期处理性能下降;堆肥湿地可显著降低AMD的酸度与重金属,出水酸度随时间持续降低,出水的Cd、Pb在检测限以下,Zn、Cu平均浓度分别为1.8mg/L, 2.6μg/L,均达到农业灌溉水标准,而无前置堆肥的普通湿地后期Cd、Zn、Cu偏高;东南景天在湿地系统也能正常富积Cd/Zn;狭叶香蒲使堆肥湿地的产碱过程受到抑制,出水酸度升高,但其对堆肥湿地的重金属去除没有产生显著影响.     

湖南省绥宁县黄桑坪自然保护区植物群落多样性分析

通过对湖南省绥宁县黄桑自然保护区的植物群落特征及物种多样性的分析,结果表明:1)可将黄桑自然保护区的滩地、撂荒地和山坡地划分为3种群落类型:鱼腥草-蕨群丛、早熟禾-井栏边草群丛和杉木+马尾松-三尖杉+水苏-莎草+地稔群丛;2)植物多样性指数的大小顺序为:Patrick丰富度指数(R)、Simpson指数(D)和ShannonWiener指数(H)的大小顺序为:山坡地(S,D,H)撂荒地(S,D,H)滩地(S,D,H),Pielou均匀度指数(E)的大小顺序为:潍地(E)撂荒地(E)山坡地(E);3)3种样地之间的物种Czekanowski相似性系数(CC)较低,在0.0001~0.356 8之间,样地内的物种相似性指数(CC)沿滩地→撂荒地→山坡地的顺序递减;(4)相关分析表明:S、D、H之间呈极显著正相关(P0.01),E与S、D、H呈显著负相关(P0.05).生境条件差异是物种多样性差异形成的直接原因.表3,参16.     

高效絮凝剂产生菌的筛选及培养条件

从活性污泥中分离出36株菌株,培养、筛选得到具有絮凝活性的菌株9株,其中有一株絮凝活性较高,命名为B-8,同时考察了培养时间、温度、pH和碳源对絮凝效果的影响。结果表明,培养时间72h,最佳温度为37℃,pH为7.0,葡萄糖为最佳碳源时,该微生物所产生的絮凝剂的絮凝效果最好,絮凝率可达95.75%。     

城市停车场火灾风险性的评价

城市大型停车场的数量随着经济的发展在迅速增长,这些新建的停车场均向高层和地下空间发展,其投资费用都较大,一旦发生火灾,往往会造成严重的经济损失和人员伤亡事故,国内外停车场发生的一系列火灾事故充分证明了这一点.因此,对停车场进行火灾风险评价具有十分重要的意义.分析了停车场火灾的特点,并从停车场的火灾场景、发生轰燃的烟气条件、释放辐射热的大小、对面汽车被引燃的临界条件等几方面对停车场潜在的火灾风险性进行了探讨.以某地下停车场为例,对其火灾风险性进行了具体评价.     

Influence of the chemical and mineralogical composition on the acidity of an abandoned copper mine in the Bor river valley (eastern Serbia)

Since the end of operations in 1987, the flotation tailing pond in the area of the former Bor River valley has been left without any type of remediation, leading to a great environmental impact on the wider surrounding area. Because the relative abundance of minerals is critical in determining the quality of the water draining from such materials, research to define the influence of the chemical and mineralogical characteristics on the acidity of the Bor flotation tailing was performed. With this aim in mind, core sampling from eight, 20-m deep drilling holes was undertaken, followed by mineralogical analysis of the composites from each drilling hole and chemical analysis of the composites of the holes and samples taken every 5 m. In addition, the tailing acidity was measured on samples from all drilling holes taken every 1 m from the surface to the base of the tailing using distilled water and 1 M KCl. The average tailing acidity was very high, with a pH value between 2.2 and 4.0 along the depth of the holes, indicating that pyrite, as the dominant sulphide mineral, was oxidised even in the deepest layers of flotation tailing.     

北京大气颗粒物数浓度粒径分布特征及与气象条件的相关性

2011年11月~2012年8月,采用WPS宽范围粒径谱仪在北京地区连续监测10nm~10μm间不同粒径大气颗粒物数浓度,并同步记录气象参数.结果表明,颗粒物数浓度均值为25014个/cm3,多呈单峰或双峰模式分布,其中冬季均值为31007个/cm3,春季23152个/cm3,夏季20882个/cm3,冬季明显高于其他季节.爱根核模态及积聚模态均呈现冬季高、春夏低的态势;核模态春季显著高于其他季节.各气象因素中,风速影响最为显著,粒径大于20nm颗粒物数浓度与风速呈反比.核模态与爱根核模态粒子数浓度在交通早高峰、正午与晚间高于其他时段,积聚模态粒子数浓度变化则相对平缓,夜间显著升高.     

石家庄春季大气气溶胶的散射特征

利用2010年5月积分浊度仪、PCASP-X2和能见度仪的观测资料,分析了石家庄大气气溶胶的散射特征及其与气溶胶粒子浓度、能见度、气象条件的关系.结果表明,观测期间,450,550,700nm 3个波段的气溶胶散射系数平均值±标准差分别为(257±293),(199±237)和(143±173)Mm-1,散射系数的变化很大,但气溶胶微物理特征相对比较稳定.散射系数日变化呈3峰分布,峰值出现在8:00、13:00和0:00.以550nm波长为例,气溶胶散射系数的变化范围为144~308Mm-1,夜间散射系数大于白天,非晴天散射系数平均值(524.9Mm-1)是晴天散射系数(112.3Mm-1)的4.7倍.气溶胶3个波段后向散射比均大于0.15,说明石家庄细粒子污染比较严重.散射系数和体积浓度成正比,但由于局地气象条件和污染源的影响,有气溶胶体积浓度变大,散射系数变化不大的情况出现.气溶胶散射系数和能见度呈负相关;根据Koschmieder公式计算得到的能见度,能较好反映实际观测情况.当大气相对湿度较高时,气溶胶散射系数随湿度增大呈现两种不同的变化趋势,即一部分气溶胶的散射系数有明显的增大,而另一部分则随着相对湿度的增加并未增大,反而比干气溶胶散射系数要小.局地风场也会影响气溶胶散射特性.     

ZrO2掺杂的V2O5/TiO2催化剂表征及催化还原NOx

采用共沉淀法制备出不同锆掺杂量的钛锆复合载体(TiO2-ZrO2),运用XRD和BET研究其微观结构,结果显示钛锆物质的量之比1∶1时复合载体具有最大的比表面积,可达256.01 m.2g-1.以此为载体制备了V2O5/TiO2-ZrO2催化剂,并添加少量CeO2对其改性.采用XRD、BET、H2-TPR、原位FT-IR等手段研究其活性组分的表面分散状态、氧化还原特性和表面酸性.结果显示,V2O5高度分散在载体上;与纯V2O5相比,复合载体上V2O5的还原峰向低温方向发生了偏移;催化剂表面包含了大量的B酸和L酸.模拟氨气催化还原NO(NH3-SCR)的脱硝反应活性测试表明,V2O5/TiO2-ZrO2催化剂具有较好的热稳定性和较宽的活性窗口,少量CeO2的加入提高了催化剂的低温活性.     

Sediment geochemistry and arsenic mobilization in shallow aquifers of the Datong basin,northern China

Understanding the mechanism of arsenic (As) mobilization from sediments to groundwater is important for water quality management in areas of endemic arsenic poisoning, such as the Datong basin in northern China. The bulk geochemistry analysis of sediment samples from three 50-m boreholes drilled specifically for this study at As-contaminated aquifers, the groundwaters of which have an As concentration up to 1060 μg/l, revealed that the average bulk concentrations of major and trace elements of the samples are similar to those of the average upper continental crust. The average As content of the sediment samples (18.7 mg/kg) is higher than that of modern unconsolidated sediments (5–10 mg/kg). Moreover, the abundance of elements varied with grain size, with higher concentrations in finer fractions of the sediments, such as silt and clay. The concentration of NH₂OH–HCl-extracted iron (Fe) strongly correlated with that of extracted As, suggesting that Fe oxyhydroxides may be the major sink of As in the aquifer. The results of microcosm experiments showed that As mobilization from sediments to groundwater is probably mainly related to changes in the redox conditions, with moderately reducing conditions being favorable for As release from sediments into groundwater.