Activated carbon is clean, porous carbon that efficiently captures impurities while letting the purified air or liquid pass through. Activated carbon has numerous applications. For example, it is suitable for filtering drinking water or recycled wastewater and for removing impurities or odors from gases.
Activated carbon can be made for example from wood, coal, or coconut husk. The ingredient affects the filtration properties of the activated carbon. Therefore, activated carbons made from different materials are suitable for different applications. The pores inside the wood-based activated carbon are large, making it optimal for retaining certain impurities with large particles. The coal-based activated carbon, in turn, is denser and more durable. Therefore, it is especially suitable for drinking water treatment. The coconut-based activated carbon is optimal for applications that require high purity because it has a very low ash content. However, the coconut carbon is dense and is therefore not suitable for capturing larger impurity particles. The best activated carbon type for each process can be determined based on laboratory or pilot testing. Haarla also offers its vast experience to recommend the right activated carbon for different applications.
Treatment of activated carbon during production
During production, activated carbon can be treated to enhance its properties. Agglomerated activated carbon is made more efficient by first pulverizing the carbon and then putting it together with a binder to reform particles. The agglomeration process increases the active surface of the activated carbon and improves its wettability and adsoption properties. Acid washed activated carbon refers to activated carbon that has been acid washed to remove the water-soluble ash. In this way, no impurities are dissolved during the commissioning, which allows for better pH control in the filter and requires shorter initial backwash time. Impregnated activated carbon means that the carbon is treated throughout with chemicals which enhance the adsorption properties of the carbon for the treatment of liquids or gases during filtration. Impregnation increases the selectivity of the activated carbon towards certain impurities. Impregnated activated carbon is well suited for filtering for example hydrogen sulfide or mercury.
Classification of activated carbon according to granular size
The production of activated carbon results in different sizes of carbon particles. These particles are sorted through sieves. The so-called Mesh size reveals the particle size of the activated carbon. The higher the Mesh size, the smaller the particle size.
Activated carbons can be categorized according to their particle size and shape. Granular Activated Carbon (GAC) is used for treating liquids and gases to remove impurities, odors, and colors. GAC, which usually has a granular size between 0.2 and 0.5 mm, requires a long contact time with the purified material, for example in a fixed filter bed. Powdered Activated Carbon (PAC) is suitable for purifying flue gases at incineration plants and for quick purification of liquid materials. Its contact time with the material is short; the activated carbon is dosed into the flowing liquid or gas and filtered out before the next process stage. The granule size of PAC is small, usually less than 0.045 mm. Pellet Activated Carbon is efficiently used for example for removing VOC’s (Volatile Organic Compounds), sulfur compounds and ammonia from gases. It requires fixed filters where the treated material passes through. The cylindrical pellets typically have a diameter of 3 or 4 mm. The large pellets are beneficial for gas applications as they cause a relatively low pressure drop.
Responsible activated carbon
Haarla has decades of experience in delivering activated carbon solutions for example for water treatment plants and the food and beverage industry. Responsible sourcing of activated carbon is important for us. Our partner Chemviron Carbon is one the world’s largest and most responsible suppliers of activated carbon. The company has achieved the EcoVadis Platinum sustainability medal, which is given to only 1% of all the companies reviewed by EcoVadis. In addition to virgin activated carbon, we also offer activated carbon reactivation services.
Our experts are at your service!
Markus Peräkylä
COO, Enviro Team Lead
markus.perakyla@haarla.com
+358 40 723 5262
