Pollution control considerations

Waste treatment prior to disposal may introduce phase changes which result in quite different pollution control considerations. For example, the gases generated by incineration of a solid waste can be scrubbed with liquid in order to meet an acceptable discharge criterion hence, in addition to ash for disposal, a liquid effluent stream is produced and requires treatment. Other waste treatment processes may result in the liberation of flammable or toxic gaseous emissions as exemplified in Table 16.5. 

Because zinc-based alloys have low melting points, energy savings in the melting operation are substantial and the foundry operation is essentially free of fume. With the current trend of increasing energy costs and pollution control, cost benefits can be considerable (114). 

Fixed Granttlar-Bed Filters Fixed-bed filters composed of granules have received considerable theoretical and experimental study [Thomas and Yoder, AMA Arch. Ind. Health, 13, 545 (1956) 13, 550 (1956) Knettig and Beeckmans, Can. J. Chem. Eng., 52, 703 (1974) Schmidt et al., J. Air Pollut. Control Assoc., 28, 143 (1978) Tardos et al.,y. Air Pollut. Control Assoc., 28, 354 (1978) and Gutfin-ger and Tardos, Atmos. Environ., 13, 853 (1979)]. The theoretical approach is the same as that used in the treatment of deep-bed fibrous filters. 

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. 

Our survey of the activities of the Government, industry and voluntary bodies in the control of pollution discloses several issues which need further enquiry. The first and most difficult of these is how to balance the considerations which determine the levels of public and private expenditure on pollution control. Some forms of pollution bear more heavily on society than others some forms are cheaper than others to control and the public are more willing to pay for some forms of pollution control than for others. There are also short and long-term considerations in the short-term the incidence of pollution control on individual industries or categories of labor may be heavy but. . . what may appear to be the cheapest policy in the short-term may prove in the long-term to have been a false economy. 

First order parameters affecting dispersion stem from meteorological conditions. These, as much as any other consideration, determine how a stack is to be designed for air pollution control purposes. Since the operant transport mechanisms are determined by the micro-meteorological conditions, any attempt to predict ground-level pollutant concentrations is dependent on a reasonable estimate of the convective and dispersive potential of the local air. The following are meteorological conditions which need to be determined ... 

Engineering Considerations To effect the good engineering design of an activated carbon adsorption system, it is first necessary to obtain information on the following the actual cubic feet per minute (ACFM) of air to be processed by the adsorber, the temperature of gas stream, the material(s) to be absorbed, the concentration of the material to be adsorbed, and if the intended application is air pollution control such as odor control - then the odor threshold of the material to be adsorbed. In addition, data is needed on the presence of other constituents in the gas stream, and whether or not solvent recovery is economical. 

This example points out one of the central problems in stack design for pollution control local, short-term effects may be the most important stack design consideration, but will usually be the aspect of the problem about which the least information is available. 

If one is considering the recovery of aroma compounds from waste gas streams, one should investigate the pollution-control literature. There are a large number of patents and scientific articles that deal with this issue. The techniques used are generally aimed at the removal of trace volatiles in air streams and are potentially suited to aroma recovery. The primary consideration is whether the techniques yield an isolate safe for human consumption. 

Energy demand, the implementation of sulfur oxide pollution controls, and the future commercialization of coal gasification and liquefaction have increased the potential for the development of considerable supplies of sulfur and sulfuric acid as a result of abatement, desulfurization and conversion processes. Lesser potential sources include shale oil, domestic tar sands and heavy oil, and unconventional sources of natural gas. Current supply sources of saleable sulfur values include refineries, sour natural gas processing and smelting operations. To this, Frasch sulfur production must be added. 

Vigon, B. W. Rubin, A.J. (1989). Practical considerations in the surfactant-aided mobilization of contaminants in aquifers. Journal of the Water Pollution Control Federation, 6l, 1233-40. 

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