The correct activated carbon is selected according to the pollutants present in the contaminated air, their concentrations and the conditions in which the filtration system will operate. Different activated carbon media have different adsorption properties, so choosing the appropriate grade is essential for reliable odour and emission control.
A carbon that performs well against volatile organic compounds (VOCs), for example, may not provide the same performance against hydrogen sulphide or ammonia. Specialist or chemically impregnated carbons can therefore be used to increase the media’s affinity for particular contaminants.
Exeon’s hi-flo™ activated carbon systems are designed around the individual application, with the carbon media selected according to the expected contaminant profile and required treatment performance.
Are There Different Types of Activated Carbon?
Yes. Activated carbon can be produced from different raw materials, including coal, wood and coconut-based materials, and can be supplied in granular or pellet form.
The carbon is processed to create a highly porous internal structure with a very large surface area. When contaminated air passes through this pore structure, suitable pollutant molecules become attached to the carbon surface through adsorption.
Different manufacturing and treatment processes alter the characteristics of the finished media. Exeon provides more detail on this process in its guide to activated carbon air treatment.
Which Carbon Is Used for Hydrogen Sulphide and Ammonia?
For contaminants such as hydrogen sulphide, mercaptans and ammonia, chemically treated or impregnated activated carbon may be selected.
Impregnation introduces chemical agents that enhance the carbon’s ability to capture or neutralise particular gases. This allows the media to be matched more closely to the pollutants found within sewage treatment, anaerobic digestion, waste handling and other industrial air streams.
Selecting an unsuitable carbon can result in reduced removal efficiency or cause the media to reach exhaustion earlier than expected.
For this reason, the contaminant profile should be understood before the carbon bed is specified rather than treating activated carbon as a single universal media.
What Factors Affect Activated Carbon Selection?
The contaminants themselves are only one part of the selection process. Factors that should be considered include:
- Type of pollutant
- Normal and peak contaminant concentrations
- Airflow rate
- Temperature
- Relative humidity
- Required removal efficiency
- Required contact time
- Presence of dust or particulate matter
- Expected operating hours
- Potential changes in process conditions
Humidity and temperature can be particularly important because they can influence adsorption performance. Exeon can incorporate pre-filtration or pre-treatment where necessary to help ensure incoming air reaches the carbon bed under appropriate conditions.
How Is the Best Carbon Confirmed for an Application?
Selecting activated carbon should begin with reliable information about the process and emissions. This may include process data, airflow measurements, gas monitoring or air sampling to determine which contaminants are present and their expected concentrations.
This information allows the carbon type, bed depth and overall treatment system to be designed together.
In some circumstances, activated carbon may not be the most appropriate primary treatment technology. Exeon also provides airo-flo™ biological filtration and scrubX™ wet scrubber systems for applications better suited to biological or liquid-phase treatment.
By considering the complete air stream rather than selecting carbon media in isolation, Exeon can design an industrial odour and emission control system that balances contaminant removal, carbon life, airflow performance and ongoing operating costs.
Correct carbon selection is therefore fundamental to achieving effective treatment and avoiding unnecessary media replacement over the working life of the system.
Contact Exeon today to arrange a site consultation or request a tailored proposal. Our technical team will assess your airflow volumes and contaminant profile to design a system that delivers consistent emission control.