Granular Activated Carbon (GAC) plays an essential role in modern water purification technologies, known for its superior ability to adsorb impurities from water. This highly effective filtration media, derived from organic materials, is used in various applications to enhance water quality by removing organic contaminants, undesirable tastes, odors, and certain harmful chemicals, including Per- and Polyfluoroalkyl Substances (PFAS).
Granular Activated Carbon (GAC) is a form of activated carbon that has been treated to create a vast network of microscopic pores, giving it a highly porous structure. This structure allows GAC to adsorb (not absorb) contaminants, effectively removing harmful substances from water and air. It is primarily produced from organic carbon-rich materials such as wood, coal, peat, or coconut shells, which are subjected to high heat and chemical activation.
The adsorption process is central to GAC’s role in water purification. As water passes through a GAC filter, the contaminants within the water are attracted to and adhere to the surface of the activated carbon granules. The highly porous internal structure of GAC provides an extensive surface area for contaminants to be adsorbed, ensuring that even trace amounts of harmful substances are captured.
While GAC effectively removes a wide range of organic compounds, it is particularly noted for its ability to filter out chemicals that produce unpleasant odors and tastes in water, such as chlorine and hydrogen sulfide. Additionally, GAC has become a critical technology in the removal of Per- and Polyfluoroalkyl Substances (PFAS), a class of harmful chemicals that have become a growing environmental concern.
GAC is widely used in both residential and industrial water treatment systems due to its versatile and efficient filtration capabilities. The most common applications include:
GAC can be installed in two primary configurations: Point-of-Use (POU) and Point-of-Entry (POE).
Point-of-Use Filters (POU): These are installed at a specific point in a water supply, usually under the kitchen sink, providing purified water directly from the tap. POU systems are ideal for removing volatile organic compounds (VOCs), pesticides, and other contaminants that affect water quality.
Point-of-Entry Filters (POE): Installed at the main water supply line entering a home or building, POE filters treat all water that flows through the plumbing system. These systems are generally used for removing more persistent contaminants, such as chlorine, chemicals causing odors, and other VOCs.
Municipalities and industries often use GAC for large-scale water treatment, especially for removing contaminants that affect water safety and taste. In public water supplies, GAC filters can be used to target contaminants like PFAS, chlorine, and other persistent organic pollutants. The high capacity of GAC filters allows them to handle large volumes of water, making them crucial in meeting water safety standards.
GAC is also extensively used in advanced tertiary treatment systems for wastewater management. In these systems, GAC plays a crucial role in polishing treated water to remove residual contaminants, improving water quality before discharge into the environment or for reuse. The tertiary filtration process can remove residual dissolved organic matter, certain pathogens, and harmful chemicals that are not eliminated during primary and secondary treatment stages.
The use of activated carbon in water treatment dates back to the early 20th century, with notable advancements that have shaped its modern applications:
The first applications of activated carbon for water purification emerged in the early 1900s. In 1906, activated charcoal was first used for dechlorination in the U.S., and by 1910, granular activated carbon was introduced in Reading, England, as part of an effort to dechlorinate drinking water. The technique was revolutionary at the time, providing a cost-effective solution for improving water taste and quality.
The development of gas masks during World War I highlighted the importance of activated carbon for filtering toxic gases. This application spurred the industrial-scale production of GAC and its subsequent use in civilian water treatment. By 1929, the first GAC filters were installed in Germany, followed by installations in the United States by 1930.
1961: The first major GAC filter was installed in a public water supply at Hopewell, Virginia, marking a significant milestone in the use of GAC in large-scale water treatment.
1965: The incorporation of GAC into a full-scale advanced tertiary wastewater treatment system in South Lake Tahoe, California, further demonstrated the versatility of GAC in handling complex contaminants.
GAC filter systems are broadly classified into two categories: whole-house filters (Point-of-Entry) and Point-of-Use filters.
Whole-house filters are installed at the main water line entering a home or building. They treat all water used within the household, providing a comprehensive solution for removing chemicals that affect water quality throughout the entire plumbing system. Whole-house filters are typically used to treat volatile organic compounds (VOCs), pesticides, herbicides, and chlorine.
Point-of-use filters are installed at specific locations, such as under the kitchen sink, to treat water at the point where it is consumed. These filters are ideal for addressing localized issues, such as the removal of chlorine, odors, and certain organic chemicals that may affect the taste of drinking water.
When used correctly in water filtration systems, GAC is not hazardous and poses no risk to water quality. However, caution must be exercised during its handling and storage, as improper use—such as inhalation of GAC dust or exposure to wet activated carbon in enclosed spaces—can lead to safety hazards. Activated carbon filters should be properly maintained and replaced according to the manufacturer's guidelines to ensure optimal performance.
Granular Activated Carbon (GAC) has become an indispensable tool in the field of water purification, offering efficient and reliable filtration for both residential and industrial applications. Its ability to adsorb a wide range of contaminants, from organic compounds to harmful chemicals like PFAS, makes it a vital technology for ensuring safe, clean drinking water. Whether used in point-of-use or whole-house systems, GAC continues to evolve, driven by its critical role in safeguarding public health and improving water quality across the globe.
Huamei Carbon Company is the leading activated carbon manufacturer in China, we supply various sizes of granular activated carbon made from bituminous coal and coconut shell.
