Does improved waste treatment have demonstrable biological benefits?

Since 1972, 10 benthic surveys and 9 static fish bioassays have been conducted to assess the impact of AVTEX Fibers, Inc. effluent on the lower South Fork of the Shenandoah River. AVTEX (formerly FMC Corp.) is a rayon and polyester fibers plant located in Front Royal, Virginia. Benthic samples were taken at four stations, one above and three below the plant discharges. Single surveys in 1972 and 1973 indicated a severe impact on the benthic community along the right side of the river, below the plant, as a result of the channelized effluent. Diversity values (¯d) were low (0–2.42) and numbers of taxa and organisms were reduced. A fish bioassay in 1973 indicated the effluent to be acutely toxic at the 34.5% level (mixture of effluent and river water). In early 1974, FMC Corp. constructed an activated sludge treatment system to reduce BOD and supplement the neutralization and chemical precipitation (zinc hydroxide and liquid-solid separation) facilities that had been used to treat waste waters since 1948. After the new equipment was placed in operation, the previously stressed area became more stable. In 1975 and 1976 the stressed area exhibited greater ¯d values (1.19–3.39) and an increased number of taxa and organisms. Bioassays showed the effluent to be acutely toxic to fish only once since 1973. The major improvements in the effluent were a 70% reduction in BOD₅ and a 60% reduction in the amount of zinc entering the river. Community conditions in 1977 indicated a partial remission of improvement, probably due to drought conditions.The rehabilitation of damaged ecosystems is a process important to all biologists. An important factor in encouraging industry to participate in this activity is evidence that improved waste treatment will often have demonstrable biological benefits rather soon. As data accumulate on the recovery process it may be possible to predict the degree of rehabilitation and time required more precisely.     

Temperature, Salinity, and Fluorescence in Southern North Sea: High-Resolution Data Sampled from a Ferry

/ In 1991 and 1992, temperature, salinity, and fluorescence were measured by automatic continuous registration using instrumentation on a ferry crossing the southern North Sea daily along a transect between Zeebrugge, Belgium, and Hull, United Kingdom. The temperature ranged between 4 and 21 degrees C off the Belgian coast and between 6 and 17 degrees C in the middle of the transect. Salinity varied between 34 and 35.5 PSU in the offshore part of the transect, but showed much larger variation along the Belgian and UK estuarine coasts. Fluorescence, which was used as a measure of phytoplankton biomass, was highest at the continental coast and lowest near the English coast. Spring blooms of phytoplankton were found along the continental coast and in the channel-influenced water; in 1991 the blooms were denser than in 1992. Some summer blooms were also recorded. Water masses could be distinguished on the basis of salinity and fluorescence patterns. The general patterns in the data are compared with the literature and discussed in relation to river discharge, light penetration, and wind speed and direction. Finally, the value of automatic and frequent measurements of fluorescence for monitoring phytoplankton is compared with less frequent observations at selected stations. It is concluded that accurate information about phytoplankton biomass can only be established from the high-frequency data. KEY WORDS: Monitoring; Sampling; North Sea; Ferry; Fluorescence; Salinity; Temperature     

Explosion temperatures and pressures of metals and other elemental dust clouds

The Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) conducted a study of the explosibility of various metals and other elemental dusts, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating explosion hazards in the minerals and metals processing industries. The dusts studied included boron, carbon, magnesium, aluminum, silicon, sulfur, titanium, chromium, iron, nickel, copper, zinc, niobium, molybdenum, tin, hafnium, tantalum, tungsten, and lead. The dusts were chosen to cover a wide range of physical properties—from the more volatile materials such as magnesium, aluminum, sulfur, and zinc to the highly “refractory” elements such as carbon, niobium, molybdenum, tantalum, and tungsten. These flammability studies were conducted in a 20-L chamber, using strong pyrotechnic ignitors. A unique multiwavelength infrared pyrometer was used to measure the temperatures. For the elemental dusts studied, all ignited and burned as air-dispersed dust clouds except for nickel, copper, molybdenum, and lead. The measured maximum explosion temperatures ranged from 1550 K for tin and tungsten powders to 2800 K for aluminum, magnesium, and titanium powders. The measured temperatures are compared to the calculated, adiabatic flame temperatures.     

Combining HAZOP with dynamic simulation—Applications for safety education

A quantitative variation of the hazard and operability analysis (HAZOP) procedure is demonstrated. The process is divided into sections and dynamic models of the separate sections are prepared. Those models are used in the framework of the HAZOP procedure to determine the magnitude of the deviations from normal operation conditions that may lead to serious accidents and to test design modification to improve the safety characteristic of the process. A process involving an exothermic reaction conducted in a semi-batch reactor is used to demonstrate the advantages of the proposed procedure and its application for safety education and operator training. The programs used for simulating the reactor are available at: ftp://ftp.bgu.ac.il/shacham/OctanoneProd/.

It is shown that the use of those programs can enhance considerably the safety education by providing tools for systematic screening of process deviation associated with possible hazardous events, determining the threshold values that may lead to such events and enabling the examination of a particular design for the adequate safe range of operation.     

不同盐度、温度下的废泥浆固化处理技术

钻井过程中产生的废钻井液对环境危害性极大,而固化处理是现阶段钻井液处理的主要研究方向。本文结合国内外关于废泥浆处理的技术资料并吸收其研究方法和已有成果,利用研发出的KG系列固化剂,根据不同盐度、温度下的废泥浆、污泥、岩屑的污染情况,研究出与之适应的固化处理方法,从而在经济和技术上保证川西地区和新疆油田的废泥浆固化处理能够有效施行。本研究改进了目前不同的盐度、温度下固化作业施工中如何确保施工质量的问题,优化了现有技术水平。     

基于DYRESM模型的太湖全年水温模拟及其在水华预警中的应用

水温是湖泊生态系统的重要驱动因子,太湖蓝藻水华暴发过程与湖泊全年水温变化密切相关。本文从水温角度出发,运用澳大利亚西澳大学水研究中心开发的一维DYRESM水动力学模型模拟了太湖2005全年的水温变化状况,并通过太湖2005年水温实测值进行了验证,模型结果较好的反应了2005年太湖逐日水温的变化情况。另外从水温角度对太湖蓝藻水华暴发阶段作出分析,为太湖蓝藻水华暴发的预测预警研究进行了方法上的准备和探索。     

脉冲燃烧控制技术在加热炉中的环保节能应用

党的十七大提出"加强能源资源节约和生态环境保护,增强可持续发展能力",这是我们党科学发展、和谐发展理念的一次升华。开发低碳能源是建设低碳城市的基本保证,清洁生产是建设低碳城市的关键。传统燃煤加热炉能耗高、污染重。P-HTAC是在蓄热式加热炉的基础上研制的先进技术,采用脉冲方式控制燃烧系统,使燃烧更充分、炉温控制更精确,为企业走上一条经济效益好、资源消耗低、环境污染少的可持续发展道路铺垫了坚实的技术基础。     

Thermal evaluation of junction and connection boxes in explosion protection

To reliably avoid potential ignition sources and thus ignition of the potentially explosive atmosphere in junction and connection boxes of type of protection Increased Safety ‘e', the self-heating shall not exceed a specified level depending on the temperature class. For the conformity assessment of such products, complex thermal tests are necessary due to the great variety of mounting types and arrangements of terminal blocks in the enclosure, depending on the enclosure size. These tests are very time-consuming for the manufacturer of junction and connection boxes or for the testing laboratory and are therefore associated with considerable costs. To reduce this effort and to ensure a uniform assessment in the conformity evaluation by a certification body, it is therefore essential to create fitting charts depending on the enclosure size.This work introduces a calculation tool by means of systematic investigations on different enclosure sizes and with different assemblies, which enables the calculation of fitting charts with justifiable effort. For this purpose, the maximum temperature in the enclosure was determined as a function of the current and the assembly at 20 ± 5 °C ambient temperature. From this, electrical and enclosure-specific constants such as the maximum permissible current per conductor and a conductor specific factor were determined and combined with an exponential dependence of the power dissipation. It is shown that this relationship is valid for an overtemperature of 40 K for compliance with temperature class T6 up to an ambient temperature of +40 °C. Finally, to verify the reliability of the calculation tool, the results are compared with the enclosure-specific rated value of the maximum power dissipation according to IEC 60079-7, 5.7.     

细水雾灭火系统作用下特大断面公路隧道火灾特性数值模拟研究

细水雾灭火系统在公路隧道中的应用引发了较多关注,但是针对特大断面公路隧道的研究仍然不足。以2种大断面及4种特大断面公路隧道为研究对象,选取额定流量35 L/min、额定压力10 MPa的高压细水雾喷头,选择4种喷头布置形式,考虑火源功率、位置、遮挡物等影响因素,以隧道顶棚达到耐火极限的临界温度和相邻车辆被引燃的临界热辐射强度为判据,利用FDS模拟软件分析得到适用于隧道的细水雾喷头布置方案。结果表明对于特大断面隧道,细水雾单排顶喷布置不能有效抑制30 MW的大货车火灾,应采用增加顶喷或侧喷喷头的布置形式,从而保护隧道结构安全,防止相邻车辆被引燃。     

pH值、温度对反硝化的影响

在悬浮污泥系统中,当以挥发性脂肪酸为碳源时,适宜的ｐＨ值是７．５。当ｐＨ偏离这一适宜值时,反硝化速率逐渐降低,亚硝酸盐出现累积。经驯化后,氮去除率会有所改善。随着温度的上升,反硝化速率会平行地提高,温度常数Ｋ_ｔ值是０．０３（１０～３０℃）。本文还讨论了亚硝酸盐积累的原因和避免的方法。