Pollutants control techniques

For VOC destruction, catalytic oxidation is one of the most in ortant air pollution control techniques. In this process VOC s are oxidised over a catalyst at temperatures much lower than those required for thermal oxidation. The temperature for 100% conversion of a given... 

Emission quotas, which include emission density zoning as a quota variant, continue to receive attention as an air pollution control technique. Their basic function is to relate allowable increments in pollution to designated land uses. They achieve... 

Furthermore, environmental quality depends on our ability to control air and water pollution. Pollution control techniques employ various materials. In addition, materials processing and refinement methods need to be improved so that they produce less environmental degradation—that is, less pollution and less despoilage of the landscape from the mining of raw materials. Also, in some materials manufacturing processes, toxic substances are produced, and the ecological impact of their disposal must be considered. 

Pohution prevention techniques must be evaluated through a thorough consideration of ah media, hence the term multimedia. This approach is a clear departure from previous pollution treatment or control techniques where it was acceptable to transfer a pollutant from one source to another in order to solve a waste problem. Such strategies merely provide short-term solutions to an ever increasing problem. As an example, air pollution control equipment prevents or reduces the discharge of waste into the air but at the same time can produce a solid (hazardous) waste problem. 

Houghland, E. S., Air quality monitoring network design by analytical techniques 111, in "Quality Assurance in Air Pollution Measurement" (E. D. Frederick, ed.). Air Pollution Control Association, Pittsburgh, 1979, pp. 181-187. 

Control Techniques for Beryllium Air Pollutants," EPA Pub. No. AP-116. U.S. Environmental Protection Agency, Research Triangle Park, NC, 1973. 

Control Technique Guidelines (CTG) EPA documents designed to assist state and local pollution authorities to achieve and maintain air quality standards for certain sources (e.g., organic emissions from solvent metal cleaning known as degreasing) through reasonably available control technologies (RACT). 

The economic factors must be considered in every application. It is important to find a technique that will meet both the technical and economical requirements. In short, pollution control costs depend on the system characteristics and the application. Some cost equations that generalize the economics of the managing systems are available in the literature. Most of these equations give rough estimates and have an accuracy of only about 30% to 50%. For a comprehensive cost comparison of different units, a detailed cost analysis based on the equipment tender proposals and the special characteristics of the project is necessary. 

Adsorption is the most widely used solvent-recovery technique and is also used for odor control. The latter application is necessary to meet statutory air pollution control requirements. Depending on the application, adsorption can be used alone or with other techniques such as incineration. " ... 

During the forties and fifties, episodes of severe air pollution occurred In a number of urban and Industrial areas. They were responsible for 111 health and In some cases caused death among the populations concerned. As the scientific and public Information base on the adverse effects of urban air pollution Increased, so did public demand for control measures. As a result, many Industrial countries Introduced comprehensive air pollution control laws at various times from the mid-fifties onwards. Industrial response to these laws led to the application of control techniques which effectively reduced the emissions of some pollutants. However there are other sources and factors which can obscure the benefits of these control actions. For example, consider urban growth. In 1980 there were 35 cities with populations over 4 million. By the year 2000 this number will nearly double to 66, and by the 2025, this number will more than double to an estimated 135 (9). In developing countries, from 1980 to the year 2000, It Is estimated that twice as many people will live In cities of a total population of 1 million or more In Latin America (101 million to 232 million) and East Asia (132 million to 262 million). Three times as many people will live In cities of 1 million or more In South Asia (106 million to 328 million) and four times as many In Africa (36 million to 155 million) (10). Accompanying this rapid growth are Increases In Industrial activity... 

Facilities for separating steam from brine and for power generation were designed by mechanical, chemical, and electrical engineers. Dissolved salts in the brine cause severe scaling and corrosion in wells and pipelines. Chemists and chemical engineers developed new production techniques to overcome these problems, as well as pollution control technology for the operation. 

Other plant-scale applications to pollution control include the flotation of suspended sewage particles by depressurizing so as to release dissolved air [Jenkins, Scherfig, and Eckhoff, Applications of Adsorptive Bubble Separation Techniques to Wastewater Treatment, in Lemlich (ed.). Adsorptive Bubble Separation Techniques, Academic, New York, 1972, chap. 14 and Richter, Internat. Chem. Eng, 16,614 (1976)]. Dissolved-air flotation is also employed in treating waste-water from pulp and paper mills [Coertze, Prog. Water TechnoL, 10, 449(1978) and Severeid, TAPPl 62(2), 61, 1979]. In addition, there is the flotation, with electrolytically released bubbles [Chambers and Cottrell, Chem. Eng, 83(16), 95 (1976)], of oily iron dust [Ellwood, Chem. Eng, 75(16), 82 (1968)] and of a variety of wastes from surface-treatment processes at the maintenance and overhaul base of an airline [Roth and Ferguson, Desalination, 23, 49 (1977)]. 

The techniques of process integration have been expanded for use in optimising mass transfer operations, and have been applied in waste reduction, water conservation, and pollution control, see Dunn and El-Halwagi (2003). 

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