微生物絮凝剂产生菌的絮凝性能

从废水处理厂和土壤中分离产絮凝剂的菌株,其中一株产絮凝剂的细菌W7—1对高岭土的絮凝活性达94％,初步鉴定该菌为Klebiella sp．,W7—1对产絮凝剂的培养条件要求简单,产絮凝剂的最佳碳源和氮源为蔗糖和牛肉膏,pH在5～10的范围内都适应絮凝剂的产生,但pH为8．0时絮凝活性最高。絮凝剂的添加量为10mL／L、絮凝体系pH为7～10时絮凝活性好,提纯后的絮凝剂产量高于其它絮凝剂近10倍,分析表明,絮凝剂成分为多糖,且有很好的热稳定性,加热至100℃、30min后絮凝活性不变。     

DSF-1菌产生的絮凝剂及处理洗煤废水的试验研究

对絮凝剂产生菌DSF 1的最适碳源、氮源进行探讨 ,考察了培养过程中培养液的粘度、絮凝活性的相互关系。提取、纯化所产絮凝剂 ,对其成分进行分析 ,并研究其在洗煤废水处理中的应用 ,同时初步探讨了该种絮凝剂的絮凝机理。结果表明 ,蔗糖与葡萄糖是DSF 1的理想碳源 ,而无机铵盐类则可作为其氮源 ;粘度和絮凝活性呈正相关性 ;DSF 1产生的絮凝剂活性成分可基本判定是阴离子型多糖 ,当用量为 0 5mL 5 0 0mg/L时 ,DSF 1产生的絮凝剂对pH =12 0、5 0mL 10g/L的模拟洗煤废水处理效果最好 ,低价 (+1,+2 )金属阳离子 (Ca2 + 、Mg2 + 、K+ 和Na+ )可以增强絮凝活性     

THE EPIDEMIOLOGY OF MONITORING1

ABSTRACT: An informal sample of 30 flawed monitoring projects was examined to identify the most common problems and to determine how they could have been prevented. Problems fall into two general categories: 70 percent of the sampled projects had design problems, and 50 percent of the sampled projects had procedural problems. Monitoring projects implemented by land‐management agencies tended to have a higher proportion of procedural problems than did university‐based programs (generally graduate student research), while the frequency of design problems was similar between agencies and universities. The most common problems were poorly trained or unmotivated field crews (37 percent of projects, a procedural problem), a sampling plan that was not capable of measuring what was needed to meet project objectives (30 percent, design), delays in analyzing data (27 percent, procedure), inadequate monitoring durations (27 percent, design), and absence of the collateral information needed to interpret results (20 percent, procedure). Most of the problems could have been avoided by submission of the study design to thorough technical and statistical review, active participation of the principal investigators in field data collection, and analysis of at least some of the data as soon as information was collected so that problems could be recognized early enough to be corrected.     

Unified correlations for vent sizing of enclosures at atmospheric and elevated pressures

Innovative vent sizing technology is presented for explosion safety design of equipment at atmospheric and elevated initial pressures. Unified correlations for vent sizing are suggested. They are modifications of previously reported correlations verified thoroughly for experimental data on vented gaseous deflagrations under different conditions but only at initial atmospheric pressure. Suggested correlations are based on experimental data on vented deflagrations of quiescent and turbulent propane–air mixtures at initial pressures up to 0.7 MPa. Typical values of turbulence factor and deflagration–outflow interaction number are obtained for experimental vented deflagrations at initial pressures higher than atmospheric.

“Blind” examination of new vent sizing technology on another set of experiments with methane–air and propane–air mixtures has shown that predictions by suggested vent sizing technology are better than by the NFPA 68 guide for “Venting of Deflagrations”.

In the development of recently reported results for initial atmospheric pressure it has been concluded that the innovative vent sizing technology is more reliable compared to the NFPA 68 guide at elevated initial pressures as well. Moreover it is crucial that the calculation procedure remains the same for arbitrary deflagration conditions.     

Demographic Effects of Harvesting Epiphytic Bromeliads and an Alternative Approach to Collection

Abstract: Hundreds of epiphytic bromeliads species are harvested from the wild for trade and for cultural uses, but little is known about the effects of this harvest. We assessed the potential demographic effects of harvesting from the wild on 2 epiphytic bromeliads: Tillandsia macdougallii, an atmospheric bromeliad (adsorbs water and nutrients directly from the atmosphere), and T. violaceae, a tank bromeliad (accumulates water and organic material between its leaves). We also examined an alternative to harvesting bromeliads from trees—the collection of fallen bromeliads from the forest floor. We censused populations of T. macdougallii each year from 2005 to 2010 and of T. violaceae from 2005 to 2008, in Oaxaca, Mexico. We also measured monthly fall rates of bromeliads over 1 year and monitored the survival of fallen bromeliads on the forest floor. The tank bromeliad had significantly higher rates of survival, reproduction, and stochastic population growth rates (λ_s) than the atmospheric bromeliad, but λ_s for both species were <1, which suggests that the populations will decline even without harvest. Elasticity patterns differed between species, but in both, survival of large individuals had high elasticity values. No fallen bromeliads survived more than 1.5 years on the forest floor and the rate of bromeliad fall was comparable to current harvest rates. Low rates of population growth recorded for the species we studied and other epiphytic bromeliads and high elasticity values for the vital rates that were most affected by harvest suggest that commercial harvesting in the wild of these species is not sustainable. We propose the collection of fallen bromeliads as an ecologically and, potentially, economically viable alternative.     

电梯井加压送风全尺寸火灾试验研究

为了研究电梯井烟囱效应、电梯运行活塞效应对电梯井加压送风的影响,获得电梯井有效防烟的临界参数,在10层高的建筑内,利用一部运行速度为1.5 m/s的电梯,开展全尺寸火灾试验。试验包括正、逆烟囱效应的工况,火灾发生在房间和通道的工况,在此基础上得到单梯井低速电梯在火灾中运行的气流特性和压差变化,电梯井有效防烟的技术参数。研究结果表明,合理的电梯井加压送风能够有效控制火灾烟气,使火灾时使用电梯疏散具有可行性。     

Modelling large-scale vented gas explosions in a twin-compartment enclosure

Natural gas and LPG are common fuels that have been used relatively safely in the home for many decades. However, when there is a release of gas within a dwelling, or gas from a leaking external pipeline migrates into a building, an explosion may occur. Most of the experimental research into vented gas explosions has been conducted in single enclosure, cuboid or spherical geometries which are not representative of accidental explosions in dwellings or process industries. This paper discusses the findings of a comprehensive large-scale experimental programme undertaken by British Gas Research and Development and also compares FLACS CFD (Computational Fluid Dynamics) simulations against a number of these experiments. The results suggest that the software is useful in gaining a greater understanding of the dynamics of explosion development in dwellings. The paper highlights areas of good performance of the software as well as areas of shortcomings where further understanding and modelling effort is needed.     

综合环境试验系统中受试产品表面Cl元素沉降聚积效果正交分析

针对综合环境试验系统中受试产品表面检出Cl元素的异常现象,提出基于正交试验的受试产品表面Cl元素沉降聚积效果分析方法。介绍试验系统工作原理与Cl元素检测方法,明确试验目标,通过前期实验筛除试验系统中与Cl元素沉降聚积无关的因素,最终确定三因素两水平的正交试验,对通风、吸波材料、试验时间等进行组合研究。通过对正交试验结果分析,发现了导致Cl元素沉降聚积量最大的多因素组合,从而为大量开展的综合环境试验中Cl元素的控制提供参考。     

脉冲清灰系统选型的理论估算及试验

脉冲清灰系统是袋式除尘器和电袋除尘器的关键技术之一。通过理论估算的方法确定系统关键参数的初值,并依靠在脉冲喷吹试验平台试验的方法来获得最优的设计参数。     

基于工作过程的高职环境实验课程教学方法研究

中国环境管理干部学院在多年环境实验教学经验的基础上,对原有实验教学模式进行改革,提出了“基于工作过程”的环境实验课程的全新教学模式。传统实验教学内容和教学方法单一,学生被动学习,不适用于新的教学模式下高职学生的培养需要。基于工作过程的高职环境实验课程教学方法以工作任务为导向,学生在实践中学习,学习中实践,教学效果良好。介绍了基于工作过程的教学方法体系确定的原则和程序,并以基于工作过程的环境实验课程为例,介绍了本课程的多模式教学方法体系及其应用。