Document ID: EPA-HQ-OW-2020-0582-0081
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2021-03-17T04:00Z

Summary of Chemours Fayetteville Works GAC Testing Data
                                 June 8, 2020
Background: Under the consent order filed in February 25, 2019 (https://www.chemours.com/en/about-chemours/global-reach/fayetteville-works/compliance-testing), the Chemours Fayetteville Works facility began its required pilot testing a Granular Activated Carbon (GAC) treatment system in September 2019 to study removal efficiencies for multiple PFAS compounds.  The treatment system consisted of pretreatment steps leading to four GAC columns arranged in series. Two studies were performed, the first study consisted of a singular treatment train utilizing Calgon F400 GAC while the second consisted of two treatment trains run in parallel to test two separate types of GAC, Calgon F400 and Calgon DSR-A. The treatment train utilizing 4 GAC units packed with Calgon F400 GAC was labeled the "`A' Train" and the other train consisting of 4 GAC units packed with Calgon DSR-A was labeled the "'B' Train". Samples were collected from the untreated influent, pretreated influent, and the effluent from each of the four columns and then tested utilizing the Table 3+ Method and Modified 537 MAX methods to determine concentrations of various PFAS compounds. 
Treatment System Design: The influent water was collected from a location at Old Outfall 2, which used to receive process wastewater but is no longer active, and transported via truck to an 18,000-gallon Frac tank, which is most commonly utilized as a water storage tank when a well is being fractured. This tank was utilized to provide consistent contaminated groundwater for several weeks of testing.  
The influent water was then pumped from the Frac tank through the batch pretreatment process which consisted of aeration, mixing, pH adjustment, polymer addition, flocculation and settling and filtration.  The influent was aerated for 30 minutes and then mixed for 15 minutes with the addition of 50% sodium hydroxide (to precipitate and remove iron) and 0.5-1.0 mg/L of anionic polymer (to enhance flocculation); the mixer was then turned off to allow for flocculation and settling. After the solids had settled, the batch was pumped through two cartridge filters (to remove fugitive solids) to a batch holding tank.  
After pretreatment, the water was continuously pumped through the GAC columns operating in series.  These columns were operated with a flow rate of 0.11 gpm which provided a hydraulic loading rate across the GAC columns of 5 gpm/ft[2]. In addition, the empty bed contact volume in each column was 5 minutes. The two treatment trains, `A' and `B' were operated in the same fashion utilizing the two types of GAC from Calgon. As a note, Calgon DSR-A, used in the `B' train, is a regenerated GAC product that is used in industrial and remediation applications.
Sampling Design: This GAC project was split into two studies. Study #1 was performed in June of 2019 and showed results on the Calgon F400 GAC. Sampling occurred for the influent, treated influent, and effluent of all 4 GAC columns. The sampling frequencies were as follows: 
 Weekly sampling for untreated influent
 Weekly sampling for pretreated influent
 Daily sampling for column 1 effluent
 3X weekly sampling for column 2 effluent
 2X weekly sampling for column 3 and 4 effluents
Sampling occurred using two different methods, the Table 3+ and the Modified 537 MAX method. The Table 3+ Method showed the concentrations of 20 PFAS analytes while the Modified 537 MAX method showed concentration for 33 PFAS analytes.
Study #2 was performed in August of 2019 and showed the difference in effectiveness between Calgon F400 GAC and Calgon DSR-A GAC. In this study, two sets of 4 GAC columns were run in parallel on the same pretreated effluent to determine which GAC was more effective. Again, the sample points, locations, and analytical methods were the same as Study #1.
Data Available: Data drawn from the testing included flow data as well as concentration data. The flow data included the elapsed time (from the sampling event), the cumulative treated flow, and the Empty Bed Contact Volumes (EBCVs) for each of the four columns. For Study #1, this data ranged from 6/14/2019 to 8/6/2019 and included 49 data points. For Study #2, this data ranged from 8/7/2019 to 9/25/2019 and included 46 data points.
For the concentration data, Study #1 was run using only Calgon F400 GAC. The data includes samples evaluated by the Table 3+ Method and the Modified 537 MAX Method. Sampling occurred between 6/13/19 and 8/1/2019 utilizing both methods on the same sampling dates. Results for the Table 3+ Method gave concentrations for 20 PFAS compounds while results for the Modified 537 MAX Method gave concentration results for 33 PFAS compounds. Study #2 was completed in the same fashion but contained 2 sets of results for each sampling date. One set of results contained data from the `A' Train, which utilized Calgon F400 GAC while the other set contained data for the `B' Train, which utilized Calgon DSR-A GAC.
Data Use: This data will be used in order to gauge the effectiveness of two different types of GAC with respect to PFAS removal efficiency. From the data, removal percentages can be calculated to show the removal efficiency for each individual PFAS compound which would determine the effectiveness of removing long- and short-chain PFAS compounds. The effectiveness of the new GAC, Calgon F400, can also be compared to that of the regenerated GAC, Calgon DSR-A.