Some Factors in Minimizing Precipitator Costs

This paper is directed to those individuals involved in design of electrostatic precipitators. The Deutsch-Anderson model is usually employed by industry for the design of electrostatic precipitators. The so-called process design variable in this approach is the total capture area in the precipitator. Unfortunately, little is available on the equipment design of this unit, i.e., the geometric arrangement of the plates that constitute the capture area and the external dimensions of the physical structure that houses the precipitator components. These are important economic considerations, and it is to this subject that this paper is directed. It is relatively easy to predict equipment costs for “off-the-shelf” electrostatic precipitators; it is more difficult to closely predict the cost for a custom-made unit, which is more often the case encountered in practice. Once the capture area is calculated, the total precipitator cost becomes a strong function of the outer casing and outer accessories of the physical system. In this paper, a model is presented that can help minimize precipitator cost. An illustrative example complements the development of the model.     

Balancing of Industrial Ventilation Systems

The body of information contained in this paper is directed to those individuals involved in the design and installation of air pollution control systems. When several sources are connected to one ventilation system, a critical part of the overall design is directed to assuring that the system is balanced so that the correct volume is exhausted from each point. The preferable technique for accomplishing this in industrial ventilation systems is the slide gate adjustment method, which can require extensive field adjustment to determine the final slide gate positions. In this study the pressure loss characteristics of slide gate dampers have been measured as a function of damper position, for both round and rectangular ductwork. Generalized graphs are presented that allow for the determination of damper position during the design phase, based on the amount of resistance that must be added to a given branch. Application of this technique indicates it to be both accurate and reliable and significantly reduces the time required to balance a system.     

On the scientific basis for global warming scenarios

The scientific basis for current projections of significant warming due to enhanced minor greenhouse gases in the atmosphere is reviewed. Care is taken to distinguish the issue of changes in radiative forcing at the earth's surface from the issue of the climatic response to this forcing. With respect to the former, it is noted that the predicted forcing is, in fact, small (2 W m(-2) at the surface for a doubling of CO(2), or less than 1% of the absorbed solar flux). With respect to the latter, it is noted that predictions of significant warming are dependent on the presence of large positive feedbacks serving to amplify the response. The largest of these feedbacks in current models involves water vapor at upper levels in the troposphere. This feedback appears to be largely a model artifact, and evidence is presented that models may even have the wrong sign for this feedback. The possibility is examined that the response of climate to major volcanic eruptions may provide a test of the climate system's amplification. The basis for this possibility is the fact that the response delay of the ocean-atmosphere system is proportional to the system gain.     

压力溶气气浮工艺中溶气效率测定方法述评

气浮工艺中溶气效率高低直接影响到回流水量的大小 ,即决定着运行费用的高低。对气浮工艺设计者和运营者来讲 ,达到并维持较高溶气效率是优先考虑的问题 ,而对新型气浮设备研发者而言 ,了解并确定其在不同工况下的溶气效率也是至关重要的。就已有溶气效率的测定方法进行了分类介绍与评价。     

The effect of dissolved glyphosate upon the sorption of copper by three selected soils

The effect of the pesticide glyphosate (GPS) on adsorption processes of copper onto three soils of different characteristics has been studied. Cu adsorption decreases in general with increasing GPS concentration in solution, due principally to the lower equilibrium pHs, although this is not the only variable affecting copper adsorption. For the same pH values, Cu adsorption is higher in two of the three soils in the presence of GPS, but for the third soil, Cu adsorption is higher in the absence of GPS. This behavior is explained by the possibility of GPS adsorption on these soils and by the formation of Cu-GPS complexes in solution. The soils showing a higher Cu adsorption in the presence of GPS than in its absence for the same pH are able to adsorb this pesticide. In these soils, copper can be adsorbed directly on the soil surfaces, and also through the formation of bonds with GPS previously adsorbed. The third soil was not able to adsorb GPS. Consequently, all the pesticide remained in solution, forming strong Cu complexes with low tendency to be adsorbed on this soil. For this reason, the concentration of free Cu in solution is drastically reduced, and the adsorption of copper on this soil is lower.     

A method for mapping the air pollution in cities with the combined use of measured and calculated concentrations

The aim of this paper is to develop the technique for mapping the air pollution in cities using measured and computed concentrations. It is based on the combined use of deterministic and stochastic modelling. Two different approaches are applied to extrapolate the measurements to the regular grid points covering the city. The first uses the method of the principal components, and the second is based on optimal interpolation or 'kriging' of meteorological fields. The results of the application of this model for the mapping of air pollution in the city of Pskov, Russia, are given.     

分段进水A/O工艺流量分配方法与策略研究

分段进水缺氧/好氧(A/O)工艺是一种高效的污水生物脱氮工艺。但原水多点投配给该工艺带来诸多好处的同时, 也为其优化运行带来一定困难。其中,可行的流量分配方法的建立是分段进水工艺发挥其优势并高效运行的瓶颈问题。提出3种不同的流量分配方法并进行相应的理论分析: (1) 采用等负荷流量分配法,其遵循的原则是保证各段硝化菌负荷相同, 以利于硝化菌生长,优先满足系统硝化, 最大程度地降低出水氨氮浓度; (2)采用流量分配系数, 原则是各缺氧段进水有机物质恰好可以为上段好氧区产生的硝酸盐氮反硝化提供充足的电子供体。 利用该方法可以充分利用原水中碳源,发挥缺氧区反硝化潜力,并保证最后一段进水量最少, 降低出水硝酸盐氮含量; (3)末端集中进水,用于暴雨等产生洪峰流量时, 将进水点向系统末端移动, 并加大末端进水量, 以减小二沉池固体负荷, 避免污泥冲刷流失。3种流量分配方法的提出,可以应对水厂不同的进水水质和出水要求,增强分段进水A/O生物脱氮工艺的实际可操作性,提高处理效率,为目前采用分段进水A/O工艺的污水厂的优化运行管理提供可靠的理论借鉴。     

Impact of wildfires on the air quality of Mexico City, 1992-1999

Wildfires in Mexico increased in 1998, compared to information for the last 6 years. The average number of wildfires in the Mexico City Metropolitan Area (MCMA) for this year (1998) were 58% (1916 events) more events than the 1992-1997 (average cases 1217 events). Mexico City affected area corresponds to 1.3% of the national affected area. The purpose of this paper is to evaluate the impact on the particles air quality due to the wildfire emissions at the MCMA and surrounding areas. Using the corresponding US EPA emission factors for wildfires, the tons of particulate matter, nitrogen oxides, carbon monoxide, and total hydrocarbons emitted by this source for the MCMA case were obtained. The calculated emissions during wildfires were correlated with the levels of particles present in the atmosphere. A comparison of the concentration levels of particles, both as PM10 as well as TSP, were made for the years 1992-1998, during wet and dry season, being March, April, and May the critical months due to the presence of wildfires. A good correlation is observed between particulate wildfire emissions and particulate air quality, being stronger for TSP. A clear impact on the particles air quality due to the increase of wildfires in 1998, is observed when this year is compared with 1997, presenting an increment of 200-300% for some monitoring stations.     

Statistical Analysis of Trends in Urban Ozone Air Quality

The purpose of this paper is to demonstrate the use of some statistical methods for examining trends in ambient ozone air quality downwind of major urban areas. To this end, daily maximum 1 -hr ozone concentrations measured over New Jersey, metropolitan New York City and Connecticut for the period 1980 to 1989 were assembled and analyzed. This paper discusses the application of the bootstrap method, extreme value statistics and a nonparametric test for evaluating trends in urban ozone air quality. The results indicate that although there is an improvement in ozone air quality downwind of New York City, there has been little change in ozone levels upwind of New York City during this ten-year period.     

Estimation of the exchange of sulphur pollution over the Balkan region in 1995–2000

The Bulgarian dispersion model 'Eulerian Model for Air Pollution' (EMAP) is used to estimate the sulphur pollution over the Balkan region for the period 1995–2000. A subdomain of the European Monitoring and Evaluation Programme (EMEP) grid is chosen containing 12 countries. The computational grid in this domain has a space step of 25 km, twice as fine as the EMEP grid. The former operational DWD 'Europa-Model' is used as meteorological driver. The source input is the official EMEP emission data. Monthly calculations are made having the last moment fields from the previous month as initial conditions for the next one. The boundary conditions are set to zero, so the influence of other European sources is not accounted for in this study. According to the EMEP methodology, multiple runs are made setting every time the sources of various countries to zero. The impact of every country in the pollution of all others is estimated.     

An air quality data analysis system for interrelating effects, standards, and needed source reductions: Part 13--Applying the EPA Proposed Guidelines for Carcinogen Risk Assessment to a set of asbestos lung cancer mortality data

The Clean Air Act Amendments of 1990 (CAAA-90) list 189 hazardous air pollutants (HAPs) for which "safe" ambient concentrations are to be determined. The primary purpose of this paper is to develop two mathematical models, lognormal and logarithmic, that effectively express excess lung cancer mortality as a function of asbestos concentration for an example set of data and also to suggest using these two models for additional HAPs. The secondary purpose of this paper is to calculate a "safe" asbestos concentration by first assuming a default linear extrapolation (to one excess death per million people, as specified for carcinogenic HAPs). The resulting "safe" concentration is an impossible-to-achieve 1/1000 of present background asbestos concentrations. A letter to the editor and a response in this Journal issue use additional asbestos data that suggest that the "safe" concentration should be about 730 times higher than first calculated here and that a default nonlinear extrapolation should be used instead, with the "safe" concentration proportional to the desired mortality level raised to the 0.39 power. These results suggest that the most important problem in setting a "safe" concentration for each carcinogenic HAP is to determine the correct nonlinear extrapolation to use for each HAP.     

A Filter Test Method For Rapid Weight Distribution Of Dust in Gas Streams To Evaluate Dust Collectors

The purpose of this paper is to describe a simple gravimetric test method that was used as a field tool to diagnose variations and malfunctions in dust collector performance. This method is not considered a replacement for accepted standard test methods for stacks.^1,2,3 Nevertheless, the reproducibility, ease, and value of this short term monitor test method over a two year period, covering over 1000 tests suggest that this method may be used effectively in the field.

The article published below is a condensed version of a paper (67-117) presented at 1967 Annual Meeting.     

Ecochemical assessment of environmental chemicals: Draft guideline of the test procedure to evaluate metabolism and degradationof chemicals by plant cell cultures

A guideline is drafted describing the screening procedure in detail. The aim for this is to facilitate an adoption of this test by bodies supervising environmental chemicals. Successful introduction of this method into the respective laboratories will cause no problems, as the procedure has been collaboratively established and improved.     

烟道喷射石灰(石)烟气脱硫技术综述

本文介绍了近几年发展起来的一种简单、中效、适合燃烧中低硫煤的工业锅炉的烟气脱硫技术———烟道喷射石灰 (石 )烟气脱硫技术。从湿法、干法、半干法 3种工艺对烟道喷射烟气脱硫进行了介绍 ,并提出新型脱硫吸收剂是提高烟道脱硫效率的可行方法。最后指出烟道脱硫今后的研究方向     

Visual modflow在模拟实验室含水砂槽中柴油运移特征中的应用

Visual modflow是一个可以对三维地下水水流和溶质运移进行数值模拟评价的标准可视化专业软件.建立了砂箱物理实验模型来研究柴油在含水砂槽中的迁移特征.通过模型检验,各个监测时期观测值和预测值相关系数r值在0.564 ～0.669之间,证明这种建模方法是合理的和有效的.利用校正的模型对实验室含水砂槽中柴油运移特征进行模拟,发现所建模型可以较为准确地反映出含水砂槽中柴油污染物的分布特征,拟合、验证和预测结果显示该模型可作为地下水管理的有效工具,这为深入研究柴油污染地下水提供理论依据.     

Revisiting the plant hyperaccumulation criteria to rare plants and earth abundant elements

The several established criteria to define a hyperaccumulator plant were applied to a rare and endangered species, Plantago almogravensis, and to the 3rd most abundant element in the earth crust, Al. Using the most common criteria, P. almogravensis undoubtedly is an Al hyperaccumulator plant. If the recent proposed requirements were considered, most of them matching those for a plant to be used in phytoextraction, it can only be considered an unusual accumulator of Al. A discussion is made concerning the several criteria of a hyperaccumulator plant in order to include rare and endemic ones and abundant elements. In ecological terms, the enrichment in Al and Fe observed may account for the differences in the vegetation pattern. Due to the rarity and endangered nature of this plant, the contribution of this work is also relevant for the ecological understanding and the development of conservation options of this endemic species.     

Omega-3 nutraceuticals,climate change and threats to the environment: The cases of Antarctic krill and Calanus finmarchicus

The nutraceutical market for EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) is promoting fishing for Euphasia superba (Antarctic krill) in the Southern Ocean and Calanus finmarchicus in Norwegian waters. This industry argues that these species are underexploited, but they are essential in their ecosystems, and climate change is altering their geographical distribution. In this perspective, we advocate the cessation of fishing for these species to produce nutraceuticals with EPA and DHA. We argue that this is possible because, contrary to what this industry promotes, the benefits of these fatty acids only seem significant to specific population groups, and not for the general population. Next, we explain that this is desirable because there is evidence that these fisheries may interact with the impact of climate change. Greener sources of EPA and DHA are already available on the market, and their reasonable use would ease pressure on the Arctic and Antarctic ecosystems.     

Development of the Tehran car driving cycle

This paper describes the development of the car driving cycle for the capital city of Tehran. Driving cycle is an essential requirement for the evaluation of the exhaust emissions using the chassis dynamometer test. In this study, the driving data are collected from several cars under real traffic conditions. The method used in this study for data analysis is based on the definition and the classification of the microtrips. The developed cycle is named TEH_CAR. The results reveal that the TEH_CAR cycle characteristics are close to the transient FTP cycle and different from the synthetic ECE cycle.     

Control of Odors and Aerosols from Spent Grain Dryers

The information contained in this paper is directed to research workers concerned with odor identification and the development of methods for removal of odorous components from hot, moist stack gases and to application engineers faced with the practical problem of selecting effective, yet economical, odor control equipment for industrial operations. The new techniques described here demonstrate the beneficial uses of gas phase reactions as a conditioning step preceding absorption in a chemically reactive solution. Cost comparisons show markedly lower costs for full-scale reactor-absorbers than for gas incinerators for equal contaminant removal. Other methods of removing odors at the source, e.g., injection of ozone, use of nonvolatile oxidizing agents in solution, and adsorption on activated charcoal, were found to be impractical, ineffective, or both. The application of reactor-absorbers to spent grain drying is discussed in detail and reference is made to the use of this technique for other food industry waste treatment processes including rendering and fish and poultry meal production.