Activated carbon

Activated carbon is a simple, highly effective solution for removing low concentrations of pollutants and odorous compounds from air streams. In industrial applications where emission limits are stringent and conventional treatment technologies become uneconomical, activated carbon provides a cost-effective way to achieve compliance. Specialized impregnated carbon grades are available to target specific contaminants and further enhance performance.

How does it work?

Where used?

Tailored to your needs

FAQ

What is activated carbon and how does it work?

Activated carbon is a form of carbon that has been thermally treated to create a highly porous structure. As a result, a relatively small amount of activated carbon can have an internal surface area of hundreds to thousands of square metres.

This vast surface area provides countless adsorption sites where pollutant molecules can attach and become trapped. As a polluted air stream passes through a bed of activated carbon, contaminants are adsorbed onto the carbon surface, allowing clean air to pass through.

Over time, the available adsorption sites become occupied and the carbon gradually becomes saturated. At this point, the activated carbon is removed and sent to a specialized regeneration facility. During regeneration, the captured pollutants are destroyed or recovered, and the carbon is thermally reactivated so it can be reused, making activated carbon a circular and sustainable treatment solution.

Where is activated carbon used?

Activated carbon is one of the most effective technologies for removing pollutants from air streams and can achieve extremely low outlet concentrations. However, because the operating cost is directly related to the amount of pollutant captured, it is generally more economical for applications with relatively low pollutant loads.

Activated carbon is particularly effective for non-polar, moderately volatile compounds, including many VOCs, solvents, and odorous organic substances. Pollutants with a high affinity for carbon can often be removed to extremely low residual concentrations.

Some pollutants require specialized carbon grades. For example, acidic compounds such as HCl, HF, and SOx are typically removed using impregnated activated carbon rather than standard carbon. Conversely, highly volatile compounds such as methane, ethane, and propane are generally not adsorbed effectively and are therefore not suitable for treatment with activated carbon.

As a result, activated carbon is most commonly used:

For air streams with low pollutant concentrations or a low average pollutant load.
As a polishing step downstream of other abatement technologies when very low emission limits must be achieved.
For the removal of trace contaminants that are difficult to capture using other treatment technologies.
For odor control applications, where even very small concentrations of pollutants can cause nuisance

Configurations tailored to your needs

Activated carbon is often used as a polishing step in a broader air treatment system. To ensure reliable and cost-effective operation, the activated carbon unit is typically installed downstream of:

A primary treatment technology that removes the bulk of the pollutants.
Air conditioning equipment that adjusts the temperature and humidity of the air stream to the optimal range for adsorption.

Because every air stream is different, the complete treatment system must be tailored to the specific process conditions, pollutant composition, and emission requirements.

For applications requiring uninterrupted operation, two activated carbon vessels are often installed in parallel. This configuration allows the system to switch from one vessel to the other when the carbon becomes saturated, ensuring continuous operation during maintenance or carbon replacement.

In more complex applications, where different pollutants require different activated carbon grades, multiple vessels can be installed in series. This allows each vessel to be filled with the most suitable carbon type, maximizing removal efficiency and extending carbon lifetime.

Frequently asked questions about activated carbon

How do I know when the carbon is saturated?

The degree of carbon saturation is typically determined by monitoring pollutant concentrations at the outlet of the activated carbon system. This can be done continuously using online analyzers or through periodic sampling and analysis.

When pollutants begin to break through the carbon bed and are detected at the outlet, the activated carbon should be replaced or regenerated. For applications requiring uninterrupted operation, systems are often designed with two vessels operating in parallel and equipped with changeover valves, allowing maintenance to be carried out without production downtime.

Can activated carbon deal with odorous compounds?

Yes. Activated carbon is one of the most widely used technologies for odor control.

Many odorous compounds have a strong affinity for activated carbon, allowing them to be effectively removed even at very low concentrations. Combined with the very low residual concentrations that can be achieved after treatment, this makes activated carbon an effective and reliable solution for a wide range of odor control applications.

How effective is activated carbon?

When properly selected and designed, activated carbon can achieve very high removal efficiencies and reduce pollutant concentrations to extremely low levels.

The actual performance depends on several factors, including the type of activated carbon, the nature of the pollutants, the condition of the incoming air stream, the degree of carbon saturation, and the design of the carbon bed. Proper air stream conditioning is often essential to achieve optimal performance.

Can any airstream be treated with activated carbon?

No.

Activated carbon performs best when the air stream is sufficiently cool and dry. In general, temperatures below 40°C are preferred, while performance decreases significantly at temperatures above 60°C.

High humidity can also negatively impact performance. Under certain conditions, water may condense within the carbon bed, blocking adsorption sites and reducing the effectiveness of the activated carbon. If necessary, the air stream should be conditioned through cooling, heating, dehumidification, or other pretreatment steps before entering the activated carbon system.

When is activated carbon a good solution?

Activated carbon is most effective when:

The total pollutant load is relatively low.
The pollutants can be effectively adsorbed by activated carbon, or a suitable impregnated carbon grade is available.
Very low outlet concentrations are required.

For air streams with a high pollutant load, other abatement technologies are often more cost-effective for removing the bulk of the contaminants. In these cases, activated carbon is commonly used as a polishing step to achieve the required emission limits.

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