How to Choose Activated Carbon for Water Treatment

Activated carbon is one of the most widely used materials in water treatment. It removes chlorine, bad tastes and odours, and many organic contaminants. But not all activated carbon performs the same, and choosing the wrong grade can mean poor results or frequent replacement. This guide explains the key factors to consider.

1. Choose the right raw material

Activated carbon is made from several raw materials, and each gives a different pore structure:

• Coconut shell carbon has mostly very small pores (micropores). It is excellent at removing small molecules such as chlorine, taste and odour compounds and volatile organic compounds (VOCs). It is also very hard, so it produces less dust and lasts longer in filter beds. It is the usual first choice for drinking water and many industrial water systems.
• Coal-based carbon has a wider range of pore sizes, which makes it better for larger organic molecules, such as those that cause colour in water.
• Wood-based carbon has larger pores and is mainly used as powdered carbon for decolourising liquids.

2. Granular or powdered?

Granular activated carbon (GAC) is packed into filter vessels that water flows through continuously. It suits drinking water, process water and point-of-use filters. Powdered activated carbon (PAC) is dosed directly into water and later removed by settling or filtration. It suits treatment plants that need to deal with occasional taste, odour or algae problems.

3. Pick a mesh size

Mesh size describes the particle size range. Smaller particles adsorb faster but create more pressure drop through the filter.

• 8×30 and 12×40: the most common sizes for water filtration.
• 4×8 and 6×12: larger granules used for gold recovery (CIP/CIL) and air or gas treatment.

4. Check the key specifications

• Iodine value (mg/g): an indicator of internal surface area and adsorption capacity. For water treatment, 900–1100 mg/g is a typical good-quality range.
• Hardness: higher hardness means less breakdown and dust during backwashing. Coconut shell carbon is usually 95% or higher.
• Ash content: lower ash usually means purer carbon and less effect on water chemistry.
• Moisture: typically 5% or less as supplied.

5. Match the carbon to your contaminant

Activated carbon is very effective for chlorine, taste, odour and many organic chemicals. It is not an effective way to remove dissolved iron and manganese, hardness, nitrates or most dissolved salts. For iron and manganese, a catalytic media such as Birm filter media is the better choice, often installed before the carbon filter.

6. Plan for replacement

Carbon gradually becomes saturated and stops adsorbing. How long it lasts depends on water quality, flow rate and the contaminants present. Signs that it needs replacing include returning chlorine taste or odour. Regular testing of the treated water is the most reliable way to decide when to change it.

Need help choosing a grade?

MDNR Resources supplies coconut shell activated carbon in 4×8, 8×30, 12×40 and custom grades, in 25 kg bags and 500 kg jumbo sacks, with COA and MSDS. Tell us your application and flow rate through our Request a Quote form and we will recommend a suitable grade.