Powdered Activated Carbon (PAC)

Powdered Activated Carbon (PAC) consists of very fine particles with a large external surface area, allowing contaminants to be adsorbed quickly. It is commonly used where contamination is temporary, seasonal or varies over time, as it can be added directly into the treatment process whenever required.

Advantages

• High adsorption rate due to its fine particle size

• Suitable for batch dosing and intermittent treatment

• Cost-effective for short-term or seasonal contamination

• Can be integrated into existing water treatment systems with minimal modifications

• Effective in removing colour, odour, taste and dissolved organic compounds

Common applications

PAC is widely used in:

• Municipal drinking water treatment

• Wastewater treatment

• Sugar and sweetener purification

• Edible oil refining

• Pharmaceutical process liquids

• Chemical processing

• Emergency contamination treatment

Limitations

While PAC offers fast adsorption, it is generally not regenerated after use. It also requires downstream filtration to remove the spent carbon, resulting in higher carbon losses compared to fixed-bed systems. Because of its fine particle size, PAC is not suitable for continuous gas-phase applications.

Granular Activated Carbon (GAC)

Granular Activated Carbon (GAC) is designed for continuous treatment processes where the carbon remains inside a fixed-bed adsorption system. Its larger particle size allows liquids to flow efficiently while providing high adsorption capacity over longer operating cycles.

One of its biggest advantages is that it can often be thermally regenerated, making it suitable for applications where long-term operating costs are an important consideration.

Advantages

• Suitable for continuous fixed-bed adsorption systems

• Good balance between adsorption capacity and flow performance

• Can often be thermally regenerated and reused

• Long operational life with relatively low operating costs

• Available in different mesh sizes to suit various process requirements

Common Applications

GAC is commonly used in:

• Drinking water filtration

• Industrial water treatment

• Groundwater remediation

• Gold recovery (CIP, CIL and CIC)

• Food and beverage purification

• Aquaculture filtration

• Low-flow VOC removal

• Catalyst support

Limitations

Compared to PAC, GAC adsorbs contaminants at a slower rate. It can also experience abrasion if handled improperly, leading to the formation of fines. While it performs well in liquid treatment systems, it is generally less suitable than pelletised carbon for high-velocity gas streams.

Pelletised (Extruded) Activated Carbon (EAC)

Pelletised Activated Carbon, also known as Extruded Activated Carbon (EAC), is primarily used in gas and air purification systems. Its uniform cylindrical shape allows gases to pass through with lower pressure drop while maintaining high mechanical strength.

These characteristics make it particularly suitable for continuous industrial air treatment applications.

Advantages

• Low pressure drop during operation

• High mechanical strength with minimal dust formation

• Well suited for continuous gas-phase purification

• Uniform pellet size for consistent performance

• Long service life and regeneration capability in many industrial applications

Common Applications

EAC is widely used for:

• Air purification

• VOC removal

• Solvent recovery

• Natural gas purification

• Biogas upgrading

• Mercury removal

• Hydrogen sulphide (H₂S) removal

• Industrial odour control

• Semiconductor process air

• Catalyst protection

Limitations

Pelletised carbon is generally not the preferred option for liquid-phase adsorption. It also has a lower external surface area than PAC and typically involves a higher initial investment. To deliver optimum performance, it should be used in properly designed adsorption vessels.

Choosing the Right Form

Rather than asking which activated carbon is ‘best,’ the better question is which form is best suited to your process.

• PAC is ideal for batch treatment, intermittent dosing and situations where contaminants appear suddenly or seasonally.

• GAC is the preferred choice for continuous liquid purification and is widely used in water treatment and gold recovery because of its long service life and regeneration potential.

• EAC is designed for gas and air treatment, where low pressure drop, high durability and consistent airflow are critical.

The right choice depends on factors such as operating conditions, flow characteristics, regeneration requirements and the design of your treatment system.