Known for its ability to remove a variety of contaminants through adsorption, granular activated carbon (GAC) is a widely used material in water treatment. Whether it’s treating a municipality’s drinking water or addressing industrial wastewater challenges, GAC plays a crucial role in ensuring clean, safe water.
In this guide, the adsorption experts at General Carbon will explore all there is to know about granular activated carbon and why you should choose it for water treatment in both industrial and municipal applications.
What is Granular Activated Carbon?
Let’s start with the basics. Granular activated carbon is an organic, highly porous material used for the adsorption of contaminants from air and water. It is made from raw, carbon-rich materials, such as wood, coconut shells, or coal, and processed at extremely high temperatures to create a large internal pore structure.
This high surface area allows GAC to efficiently adsorb a wide range of impurities and organic contaminants, including chlorine, volatile organic compounds (VOCs), pesticides, and other pollutants.
The Process of Using Granular Activated Carbon in Water Treatment
In water treatment, GAC adsorbers purify water via the process of adsorption. Physical adsorption is when organic molecules adsorb into the internal pore structure using Van der Waal’s forces. Chemical adsorption is a reaction that takes place on the surface of the carbon particle. The impurities that get adsorbed include:
- Organic compounds (chemicals such as pesticides, herbicides, VOCs, and industrial solvents) are physically adsorbed.
- Chlorine and chloramine (used in some municipal water systems as disinfectants) are chemically adsorbed.
- Unpleasant tastes and odors are physically adsorbed.
- Trace amounts of heavy metals are both chemically and physically adsorbed.
To meet treatment objectives, GAC adsorbers are frequently used in conjunction with other unit processes, such as reverse osmosis, sediment filtration, and UV disinfection.
Key Advantages of Granular Activated Carbon in Water Treatment Systems
For water treatment applications, granular activated carbon offers several key benefits:
- Superior adsorption capabilities for a wide range of contaminants.
- High porosity and surface area for efficient adsorption.
- Versatile usage in both point-of-entry (POE) systems and industrial filtration.
- Environmentally safe and chemical-free adsorption method that doesn’t introduce chemicals into the water.
- Cost-effective, affordable medium that is easy to maintain and replace.
- Compatible with other unit processes, such as reverse osmosis, to provide a comprehensive water treatment solution.
Bituminous Coal-Based GAC vs. Other Carbon Types
As previously mentioned, granular activated carbon can be made from a variety of carbon sources, but the most common sources are bituminous coal, coconut shells, and wood. Each source offers its own distinct characteristics in terms of performance and suitability for specific water treatment applications.
Bituminous coal is a fossil fuel processed at high temperatures to make activated carbon and is one of the most widely used sources for GAC production. It has a dense structure that allows for the adsorption of a broad size range of organic molecules, and hardness that makes it durable and gives it a longer lifespan. It is most beneficial for the removal of chlorine, and a broad range of organic molecules.
Coconut shell-based GAC is made from the outer shells of coconuts that have undergone a special activation process to increase the porosity. This type of activated carbon has the highest porosity and is ideal for adsorbing smaller molecules, such as small VOCs. It is especially effective in drinking water purification.
Wood-based GAC is made from hardwoods or softwoods that have been pulverized, carbonized at high temperatures, and then heated in an activation kiln where it’s exposed to steam, carbon dioxide, or air to oxidize it. This type of GAC is best for removing taste, color, and odor from water, due to its larger internal pore structure.
How Granular Activated Carbon Enhances Point-of-Entry Water Filtration Systems
Also known as a whole-house water treatment system, a point-of-entry (POE) water treatment system is an installed device that uses GAC adsorbers to treat water that enters a home or building before it reaches any faucets, appliances, or industrial equipment. This type of system is typically installed at the main water line. By contrast, a point-of-use (POU) system is a device installed on a single faucet that treats water at only this one tap (e.g., under the kitchen sink).
For residential users, POE systems provide comprehensive water treatment for the whole house and have the following benefits:
- Removes chlorine, VOCs, and heavy metals, especially helpful for houses dependent on well water.
- Cleaner water for drinking, cleaning skin and hair, and providing protection against waterborne diseases.
- Meets drinking water quality standards.
- Reduces sediment, scale, and corrosion in plumbing and appliances.
In industrial applications, POE systems can help industrial processes run more efficiently and have the following benefits:
- Consistent water quality across the facility, which is critical for industries where water quality can directly affect the product outcomes.
- Removes contaminants from wastewater and water used in industrial processes.
- Reduces maintenance costs and improves efficiency of industrial equipment.
- Meets industrial water quality standards (e.g., EPA, FDA).
- Protects machinery, boilers, and cooling systems from damage due to poor water quality.
Granular Activated Carbon: Large-Scale Solutions For Industrial Applications
GAC is widely used in large-scale industrial water treatment systems — especially in industries such as chemical processing, food and beverage, and pharmaceuticals — where water quality is critical for operational efficiency and regulatory compliance. In these sectors, the high adsorption capacity of GAC allows it to trap and remove harmful contaminants that could damage equipment and ruin water quality.
In addition, GAC is critical in helping maintain compliance with strict environmental regulations. By removing pollutants and improving water quality, GAC adsorbers contribute to sustainability and reduce the risk of incurring costly fines from a lapse in compliance.
Selecting the Best Granular Activated Carbon for Effective Water Treatment
Selecting the appropriate GAC adsorber is essential to ensure optimal removal efficiency and long-term performance. The type of granular activated carbon you choose should be based on your specific water treatment needs. The following are some factors to consider:
- Carbon source
- Particle size
- Adsorption capacity
- Intended use (residential, commercial, industrial)
- Type and amount of contaminants in the water
- How the water is being used
Note that bituminous coal-based GAC is the most appropriate choice for large-scale, high-flow industrial and municipal applications, where the removal of a broad range of contaminants and industrial pollutants are of top concern. An example of activated carbon made from bituminous coal is our GC 8×30.
Always choose GAC from a reputable source with a proven track record in industrial adsorption, such as General Carbon. Checking customer reviews from other industry clients can also be helpful.
The Environmental Impact and Sustainability of Using Granular Activated Carbon
GAC is made from renewable resources that make it more environmentally sustainable than other media that rely on non-renewable sources. Coconut shell-based GAC is the most environmentally friendly type of activated carbon since it doesn’t introduce any chemicals into the water.
In addition, while GAC loses its usefulness once it becomes saturated with contaminants, GAC can be thermally reactivated, which allows adsorbed contaminants to be released from the pore structure. Essentially, the GAC can be reused, which, ultimately, helps reduce waste.
To adhere to EPA standards, municipalities can benefit from using treatment systems with select grades of GAC to treat drinking water for lead and PFOA/PFOs (lab-made chemicals found in water that have negative health and environmental consequences). When drinking water is not properly treated, it can lead to a city-wide water crisis that endangers its population.
The Flint, Michigan, Water Crisis that began over a decade ago is a prime example of city officials failing to properly treat the highly corrosive river water being pumped to its citizens. As a result, lead leached into the water supply of thousands of homes. Water from the tap tasted bad, smelled foul, and caused severe elevation of blood-lead levels in children.
The Importance of Granular Activated Carbon in Water Treatment
Due to its high adsorption capacity and versatility in various systems, GAC is a highly effective media in both residential and industrial water treatment applications. By understanding GAC and its unique benefits, you can make an informed choice that ensures clean, safe water for a variety of applications.
Industries searching for optimal adsorption solutions for improved water quality should consider GAC for their water treatment systems. To learn more or to purchase granular activated carbon, contact General Carbon today by using the form below or calling (973) 523-2223.