Helena Joyce
Gaseous pollutants can be controlled through absorption, which involves the transfer of a gaseous pollutant from the air into a contacting liquid, such as water. Wet scrubbers are a common method of absorption, and can be used to control suspended particulates. Gas absorption can also be carried out in packed scrubbers, or towers, in which the liquid is present on a wetted surface rather than as droplets suspended in the air.
| Characteristics | Values |
|---|---|
| Absorption | The transfer of a gaseous pollutant from the air into a contacting liquid, such as water |
| Wet scrubbers | Similar to those used for controlling suspended particulates |
| Packed scrubbers | Liquid is present on a wetted surface rather than as droplets suspended in the air |
| Countercurrent tower | A common type of packed scrubber |
| Incineration | A waste treatment process that involves the combustion of organic substances |
| Electrostatic precipitator (ESP) | A filterless device that removes fine particles, like dust and smoke, from a flowing gas using the force of an induced electrostatic charge |
Absorption
Gas absorption can also be carried out in packed scrubbers or towers, where the liquid is present on a wetted surface rather than as droplets suspended in the air. A common type of packed scrubber is the countercurrent tower.
However, absorption may not be suitable for all gas streams. If the target gas stream contains particulates or biological impurities, these can increase the potential for plugging media, biologic growth, and pump and piping degradation. Therefore, absorption is just one of several technologies available for controlling gaseous pollutants, with alternatives including oxidation and incineration.
Preserving the Anacostia: Preventing Pollution for a Healthy Future
You may want to see also
Wet scrubbers
The process of gas absorption can also be carried out in packed scrubbers or towers, where the liquid is present on a wetted surface rather than as droplets suspended in the air. A common type of packed scrubber is the countercurrent tower.
Human Pollution: Everywhere Impacting Our Environment
You may want to see also
Packed scrubbers
In the context of air pollution control, absorption involves the transfer of a gaseous pollutant from the air into a contacting liquid, such as water. The liquid must be able to serve as a solvent for the pollutant or to capture it by means of a chemical reaction.
Wet scrubbers are the most common form of absorption. They are a generic name for a control device that uses the process of absorption to separate the pollutant from a gas stream.
Air Pollutants: A Cancer Risk?
You may want to see also
Incineration
During incineration, the waste is fed into a combustion chamber, where it is burned in the presence of oxygen. This process releases heat energy, which can be captured and used to generate electricity. The combustion of organic substances results in the formation of ash, which can be disposed of in landfills or used in other applications, such as construction materials.
One of the key advantages of incineration is its ability to reduce the volume of waste that requires disposal. Incineration can also help to recover energy from waste materials, contributing to a more sustainable and circular economy. Additionally, incineration can effectively destroy harmful organic substances, reducing their impact on the environment and human health.
However, it is important to note that incineration can also result in the formation of air pollutants, such as nitrogen oxides (NOx) and sulfur oxides (SOx). These pollutants can contribute to acid rain and have negative impacts on air quality. Therefore, it is crucial to implement proper pollution control measures, such as scrubbers or electrostatic precipitators, to capture and remove these pollutants before they are released into the atmosphere.
Polluting Plants: Growth Impact and Environmental Concerns
You may want to see also
Electrostatic precipitators
Dry electrostatic precipitators operate above the dew point of the gas stream to remove impurities from smoke and dust. Wet electrostatic precipitators, in contrast, operate with saturated airstreams that have 100% relative humidity. Wet precipitators are commonly used to remove liquid droplets, including oil, resin, tar, and sulfuric acid mist, from gas streams in industrial settings. They are applied where the gases are laden with humidity, contain combustible particulates, or have particles that can be sticky.
In an ESP, particles are removed when the dirty gas stream passes across high-voltage wires, usually carrying a large negative DC voltage. The particles are electrically charged on passage past these electrodes and then migrate through the electrostatic field to a grounded collection electrode. ESPs are capable of collection efficiencies greater than 99%. An ESP is primarily made up of the following four components: gas distribution plates, discharge electrodes, collection surfaces (either plates or pipes) and rappers. The gas distribution plates consist of several perforated plates which help maintain proper flow distribution of the entering gas stream.
Lead's Dark Cloud: Air Quality's Silent Polluter
You may want to see also
Frequently asked questions
Absorption is one method, which involves the transfer of a gaseous pollutant from the air into a contacting liquid, such as water.
Absorption can be carried out in packed scrubbers, or towers, in which the liquid is present on a wetted surface rather than as droplets suspended in the air. A common type of packed scrubber is the countercurrent tower.
Gaseous air pollutants can be natural or synthetic and include acid gases, inorganic gases and organic gases.
Examples of gaseous air pollutants include hydrochloric acid, sulfuric acid, hydrogen sulfide, sulfur oxides, nitrogen oxides, ammonia, ethylene, benzene, ethanol and volatile organic compounds (VOCs).
