QA intro here

The Process

How does granular activated carbon (GAC) remove PFAS from water sources?

GAC works through a process known as adsorption. In this process, the activated carbon can be thought of as a magnet that is removing contaminants from water as it passes through. Once that activated carbon is no longer removing contaminants, it is replaced with fresh or reactivated carbon so that you have continuous removal.

What is reactivated carbon?

Reactivated carbon is GAC that has been thermally treated once it is at the end of its useful service life, when it is known as spent carbon. It goes through a process that vaporizes and destroys adsorbed contaminants at extremely high temperatures and restores the GAC to a near-virgin state so it can be reused.

What exactly does the reactivation process look like?

In reactivation, the spent activated carbon travels through a multi-hearth furnace or rotary kiln, which restores the activated carbon to a virgin-like state. Using thermal treatment at high temperatures of up to 1750 degrees Fahrenheit, this step vaporizes and destroys contaminants in the furnace or kiln itself. The goal of this first step of reactivation is to restore the structure of the activated carbon, and the operating conditions (temperature and steam addition) are tuned for that purpose. 

What happens to the contaminants after they are removed from the GAC?

Any contaminants that survive the high-temperature furnace travel to the abatement system for further destruction. Wanting to know what happens to the PFAS, we were the first activated carbon company to include the abatement part of the process. 

What does the abatement system look like?

The pollution abatement system for reactivation consists of a thermal oxidizer / afterburner, a scrubber, and a baghouse. Our abatement system is designed to destroy organics to meet regulatory limits, typically to at least 99.99% efficiency. The system also neutralizes acid gases formed during the process and captures particulates.

Are there other processes that can be used to remove contaminants from GAC?

There is carbon regeneration, which uses a lower-temperature treatment – typically below 400 degrees Fahrenheit with steam, nitrogen, or other hot gas – for short periods of time to remove only a portion of the adsorbed contaminants, producing a partially spent carbon that contains some, and potentially all, of the original contaminants.

We do not use the carbon regeneration process, but instead a reactivation process that relies on thermal treatment at high temperatures greater than 1700 degrees Fahrenheit for hours at a time.


Our FILTRASORB is a re-agglomerated GAC produced from bituminous coal that has demonstrated superior PFAS-removal capabilities compared to other carbons and acts as a high-performing carbon for a variety of other compounds as well.

We offer a full range of GAC adsorption equipment and activated carbon products to treat PFAS. This simple and effective solution requires little operator involvement. Our equipment is uniquely designed to ensure no water escapes without being in contact with our activated carbon product. In an application with no room for error, choosing the right equipment and the right carbon is critical.

The Research

Why did Calgon Carbon conduct a study on the reactivation processes?

To address questions that have persisted about the effectiveness of the reactivation process for the destruction of PFAS, we did a thorough stack testing program at a full-scale, company-owned GAC reactivation facility during the reactivation of a load of GAC known to contain a high level of adsorbed PFAS.

What did Calgon Carbon find in its study?

The data from our stack testing program demonstrate that reactivation of PFAS-laden GAC in a facility operating a multi-hearth furnace with appropriate abatement system results in high levels of destruction of PFAS compounds – including full removal of PFAS compounds from GAC and greater than 99.99% destruction of PFAS compounds through the furnace and abatement system.

What was the most significant finding of the study?

The most significant finding is the confirmation that not only is PFAS removed from the activated carbon to below detectable levels, but PFAS destruction occurs in the reactivation furnace and robust abatement systems.

Why are the findings of the study important?

Our research is critical in this space. Everyone wants to know what happens to PFAS once they are removed from water. This research demonstrates that, through our proprietary reactivation process, we can remove PFAS from the activated carbon and destroy them to greater than 99.99%. The research is critical in answering the question, “What happens to PFAS once they are removed from the water?”

Was anyone else involved in this study?

We contracted with a third-party vendor specializing in manufacturing emissions testing to determine the emission rates of PFAS and hydrogen fluoride per established methodology. Additional outside vendors tested air samples for 36 PFAS compounds and analyzed well water and treated motive water samples for PFAS and analyzed samples of spent carbon, reactivated carbon, abatement dust, and bicarbonate raw materials for extraction and targeted PFAS.

About Calgon Carbon

Who is Calgon Carbon?

We are the unrivaled authority in the treatment of PFAS, combining proven and effective products, processes, and testing programs with a team of professionals focused on safeguarding local water supplies.

We are the largest, most capable and most diverse activated carbon manufacturer and supplier. 

We set the standard for the industry with hundreds of patents and a team of scientists and engineers dedicated to developing new processes, standards, and methods.

What does Calgon Carbon specialize in?

We specialize in on-site support, providing a host of top-notch field services to install and remove carbon in the most efficient and safe manner – maximizing the customer’s economic benefits and minimizing disruptions to the operations.

How did Calgon Carbon get started?

We started in the 1940s, providing activated carbon solutions for the U.S. military. Over time, we evolved. We became pioneers in drinking water treatment and have a long legacy of solving customer problems for a variety of applications. With more than 75 years of experience, we are trusted, and we are proven.

What are the treatment solutions that Calgon Carbon offers?

For its industrial customers, we treat not just water but also the environment. The company offers a wide range of treatment solutions depending on the site challenge and discharge permit criteria. We offer PFAS treatment solutions for wastewater, air, process water, landfill leachate, and groundwater remediation.

How do I go about implementing the PFAS treatment process?

Our technical team can assist with testing and simulation to determine the optimal PFAS treatment configuration for municipal and industrial settings.  This collaboration offers the most cost-effective investment process, which helps clients avoid mistakes that could increase the cost and timeline for effective treatment.

How do I know Calgon Carbon is reliable?

Our technical experts know that testing helps them determine the best treatment option. As a result, we perform more tests than any other manufacturer and have more capabilities than our competitors. Thorough testing determines the best course of treatment, including ion exchange or GAC.