Tray for cleaning waste air - inside

Effective waste air purification systems

Waste air purification is an important process in various industries to remove harmful contaminants from exhaust air. In this article, we will look at the basics of exhaust air purification, consider different types of exhaust air purification systems, examine their applications in different industries, discuss how to choose the right waste air purification systems and take a look at the future of waste air purification.

Basics of waste air purification

Waste air purification refers to the process of removing harmful contaminants from the waste air generated during industrial processes. This improves air quality and reduces negative effects on the environment and human health. Absorptive waste air purification is an important part of many industries, including the chemical industry, metal processing and power generation. By using efficient waste air purification systems, companies can control their emissions and ensure compliance with environmental regulations.

What is waste air purification?
Waste air purification involves the use of various technologies and systems to remove harmful particles, gases or vapors from waste air. Their concentration is reduced by filters or chemical treatment. There are different types of waste air purification systems, including separators, filter systems, adsorption systems and catalytic converters. Each system has their own advantages and disadvantages and is used depending on the type of contaminants and the specific requirements of the industry.

Why is waste air purification important?
Waste air purification is important to reduce harmful emissions and reduce environmental pollution. Industrial processes can generate pollutants that can contaminate air, water and soil. The contaminants can be controlled and reduced through the use of exhaust air purification systems. Waste air purification can also protect the health of the employees in industrial facilities. Harmful contaminants in the exhaust air can lead to respiratory diseases, allergies and other health issues. The risk of such health effects is minimized by removing these contaminants. Waste air purification is also an important part of environmental compliance. Many countries have strict regulations on the emission of contaminants. Companies must ensure that they comply with these regulations in order to avoid penalties and maintain their reputation as an environmentally conscious company.

Industrial chimney
Industrial chimney
Depending on the type of contamination and the specific requirements of the industry, there are different types of waste air purification systems that can be used.

Variants for cleaning waste air


Activated carbon has a large surface area that can adsorb dissolved particles. The carbon acts as a reducing agent and can absorb oxidizing agents such as ozone and chlorine from the waste air and from process and waste water. The absorbed substances concentrate in the carbon. Depending on the type of activated carbon, concentrations of ten to around 20 percent by weight are possible. Then a breakthrough occurs. Exhausted activated carbon is replaced. The absorbed solids increase the filter resistance and have to be removed from the filter bed. The filter can be regenerated by washing, heating or replacing the activated carbon.

Thermal post-combustion:

Thermal post-combustion requires temperatures of up to 900°C and sufficient residence time in the combustion area. In the simplest case, thermal post-combustion can take place in other industrial combustion plants (e.g. boiler houses). Otherwise, the necessary temperature must be generated by additional fuels. The process then becomes very complex and generates additional air pollution. During thermal post-combustion, the waste gases are completely converted to water and carbon dioxide, except for the foreign elements nitrogen, sulphur and halogens. 


Contaminants from the waste gas are condensed by the cooling of the waste gas line. The concentration of a solvent (e.g. nitrogen or air) depends on the temperature. At lower temperatures, less volatile gases can be absorbed. The waste air is cooled to a temperature that complies with the legally prescribed limit values by condensing the solvents. The highly volatile, organic components in the waste air stream are present as liquid condensate after the process. They can either be returned to the production process, purified, disposed or sold. The cryo-condensation process is typically used to separate alcohols, alkanes, chlorinated hydrocarbons or aromatics. Cryo-condensation offers an efficient and sustainable solution to make waste air purification economical.

Physical waste air purification systems:

Physical waste air purification systems use physical processes like filtration, absorption or adsorption to remove contaminants from waste air. These technologies are effective in removing particles and suspended solids.
An example of a physical waste air purification system is a dust filter. This filter consists of different layers that trap the particles in the exhaust air. The waste air is cleaned and cleared of harmful substances through filtration. Physical waste air purification systems can also use absorption or adsorption processes. Physical waste air purification systems can also use absorption or adsorption processes. In absorption, the contaminants are absorbed by an absorbent material. In adsorption, the contaminants stick to the surface of an adsorbent material

Chemical waste air purification systems:

Chemical waste air purification systems use chemical reactions to neutralize or convert harmful gases or vapours in the waste air. This is often achieved through the use of chemicals or catalysts. An example for a chemical waste air purification system is a scrubber system. This system uses a liquid that is brought into contact with the harmful gases or vapors. Chemical reactions neutralize the contaminants and the purified waste air is released.
Catalysts are also an important component of chemical waste air purification systems. They accelerate the chemical reactions and enable a more efficient conversion of the harmful compounds.

Biological waste air purification systems:
Biological waste air purification systems can be especially effective in the treatment of organic compounds. Biological processes such as microorganisms or plants break down or recycle harmful contaminants in the exhaust air. An example for a biological waste air purification system is a biofilter system. In this system, the harmful contaminants are broken down by microorganisms. The waste air is passed through a filter filled with a mixture of organic material and microorganisms. The microorganisms decompose the contaminants and convert them into harmless substances. In addition to biofilter systems, plants can also be used to clean the exhaust air. Plants have the ability to absorb harmful substances and convert them into oxygen. This process, known as phytoremediation, can be an effective and sustainable method of exhaust air purification in certain cases.

Application of waste air purification systems in various industries

Waste air purification systems are used in various industries to help break down contaminants and ensure compliance with environmental regulations.

Waste air purification in the food industry

In the food industry, waste air purification systems are used to remove odors and vapors. These can occur during cooking or roasting. Purification helps to improve the air quality in production facilities and protects employees from harmful vapors. One example of the use of waste air purification systems in the food industry is the processing of coffee beans. During the roasting process, various volatile organic compounds are released that can cause unpleasant odors. By using waste air purification systems, these odors can be effectively removed to create a pleasant working environment for employees. In addition, waste air purification systems are also used in baking ovens to extract and purify the vapors generated during the production of baked goods. This helps to improve the air quality in bakehouses and ensures compliance with hygiene regulations.

Factory premises
Factory premises

Waste air purification in the chemical industry

The chemical industry often produces harmful gases or vapors that can be released into the air. Waste air purification systems play an important role in capturing and cleaning these contaminants to prevent air pollution and ensure the safety of employees.In chemical production plants, exhaust air purification systems are used to separate hazardous chemical compounds from the exhaust air. Specialized filters and separators can efficiently remove harmful substances.In addition to cleaning the waste air, waste air purification systems are often used in the chemical industry to optimize energy consumption. The thermal energy in the waste air can be recovered by heat recovery systems and used for other processes in the production system.

Loaded waste air filter
Loaded waste air filter

Waste air purification in the metalworking industry

In the metalworking industry, harmful particles or gases are often released during the processing of metals. Welding, for example, produces harmful welding fumes that can be hazardous to health. These welding fumes can be extracted and cleaned using waste air purification systems in order to protect the health of employees.Exhaust air purification systems are also used for the surface treatment of metals. Chemical coatings or solvents can produce harmful vapors that can be removed by waste air purification systems. This helps to improve the air quality in production facilities and ensures compliance with environmental regulations.

Metalwork in the industry
Metalwork in the industry

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