Source Control Technology

Air quality management sets the tools to control air pollutant emissions. This control technology or control measurements describes the equipment, processes or actions used to reduce air pollution. The extent of pollution reduction varies among technologies and measures. In general, control technologies and measures that do the best job of reducing pollution will be required in the areas with the worst pollution. The selection of control technologies depends on environmental, engineering, economic factors and pollutant type.

Some techniques to control air pollutant emissions do not require additional equipment, while other techniques require "add-on" controls. Add-on controls are equipment added to a pollution generating process to destroy or capture the pollutants. Techniques to curb air pollutant emissions without using add-on controls include: process changes, changes in fuel, good operating practices and plant shutdowns. These control methods work equally well for gaseous and particulate pollutants. An example of a process change might be the conversion from a power source using fossil fuel to one using solar or hydroelectric power. Solar and hydroelectric power generators produce less air pollution than do generators that burn fossil fuels. An example of a change in fuel would be to use coal with low sulfur content, rather than coal with high sulfur content. This would reduce the amount of sulfur dioxide emissions. Another example of a fuel change would be to replace coal with natural gas, a less polluting fuel.

Good operating practices include common sense measures, such as good housekeeping and proper maintenance. An example is the use of a regular inspection and maintenance system to ensure that volatile organic compounds are not emitted by leaking equipment in a chemical plant. Equipment leaks can be a large source of volatile organic compound emissions. A regular inspection program using simple leak detection devices, coupled with a prompt repair and maintenance system, can greatly reduce this source of emissions. In addition to reducing emissions, good housekeeping and maintenance practices can also result in cost savings to a plant by reducing losses of valuable materials.

Finally, plant shutdowns are an effective pollution reduction technique. Plant shutdowns might be necessary in extreme cases, such as during an air pollution episode. Replacing old and outdated plants with modernized facilities is also effective in reducing air pollution. In this unit we will describe some techniques used to control particulate and gaseous pollutants from stationary sources and pollutants from mobile sources.