Progress 07/01/23 to 06/30/24

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Summary Report of The Findings from HGF and the University at Albany for USDA Phase I SBIR/STTR Project Submitted to: Lee Khan, Co-PI of this project, Founder, HGF Prepared by: Dr. Manisha Choudhary Department of Civil and Environmental Engineering, University of Maine, Orono, ME 04469 May 21, 2024 Correspondence: manisha.choudhary@maine.edu The summary report consolidates findings from HGF and the University at Albany (UAlbany), focused on using biochar-enhanced phytoremediation to extract and destroy per- and polyfluoroalkyl substances (PFAS) from contaminated soils. The findings of this research provide a step towards the development of a solution for small and mid-sized farms by demonstrating the effectiveness of biochar-enhanced phytoremediation and thermal destruction methods in removing and destroying PFAS from contaminated soils. This aims to improve the condition of PFAS-contaminated agricultural lands, ensuring farm produce's safety after the soil remediation. The project has two main objectives: (i) Enhance PFAS uptake in plants: Investigate whether adding biochar to the contaminated farm soil improves the uptake of PFAS by plants, and (ii) Destroy PFAS in biomass: Evaluate the effectiveness of hydrothermal liquefaction (HTL) and high-temperature gasification process in destroying PFAS contained within the harvested plant biomass. To achieve the first goal, three PFAS-contaminated sites in Maine were identified, and the contaminated soils were analyzed to determine the various types of PFAS and their concentrations. These soils were then amended with varying concentrations of biochar to determine the optimal amount for enhancing PFAS uptake by plants. Subsequently, three suitable crop species were selected for the uptake of PFAS from these contaminated soils. To identify the soils for this project, three locations in Maine - Presque Isle (PI), Arundel (AR), and Machias Airport (KMVM) - were selected based on the different types of soils and different sources of PFAS contamination. The soil from PI was Conant Silt Loam, and the source of PFAS contamination was septic sludge spread on the ground adjacent to the water/sewer dewatering facility. AR was Buxton Silt Loam and the PFAS contamination source was Kennebunk sludge from the water/sewer department, with the spreading starting in the 1980s. MA was Lamoine Silt loam to Lamoine Scantic complex, and the contamination originated due to firefighter foam sprayed at the airport. The soil samples were analyzed at UAlbany using EPA Draft Method 1633. Seven PFAS, including PFOA, PFNA, PFDA, PFBS, PFHxS, PFOS, and NEtFOSAA, were detected in all soils from all the sites. Among all quantified PFAS, the concentration of PFOS was highest, followed by PFDA and PFOA. The same three soil samples were also analyzed by a commercial lab (the name and details of the lab are not mentioned in the provided report). Almost similar results were provided by the commercial lab; however, a report with the detailed method used by this commercial lab was not provided. The analysis report, titled Interim Technical Report-March 22, 2024, is attached with this summary. In the following step, the study utilized three different soil samples from the aforementioned sites. The soils were amended with varying concentrations of biochar (0.05, 0.2, and 1%, dry weight based) and planted with hemp and two types of native species of grasses: orchard grass (OG) and timothy grass (TG). The plants were maintained in the greenhouse at constant temperature and humidity. The analysis of biomass amount (plant growth measurement) and PFAS update by the shoots of plants (above-ground biomass) was monitored after 45 and 90 days of the growth period. Overall, it was observed that biochar has the potential to increase the growth of all three plants. However, the exact effect depends on the soil type, plant species, and biochar dose. It should be noted that no controls without biochar amendment were established. The lack of this set of controls restricts the conclusion of how plants grow in the original soils, which will be addressed in future work, as mentioned by Co-PI Lee Khan. Furthermore, the removal of PFAS was highest from the KMVM soil among all three soils. This is consistent with the superior growth of all three plants in this soil during the greenhouse growth period. The results showed that hemp was generally more effective than the two grass species in up-taking total PFAS at biochar dosing of 0.05% from all the soils. For TG, the optimum dose of biochar for all the oils for the highest PFAS update was 0.2%. The optimum dose of biochar to achieve the highest PFAS uptake varied from soil to soil. It was observed that biochar has the potential to enhance the uptake of PFAS by all three plants. However, the exact effect depends on the soil type, plant species, biochar dose and type of PFAS. For example, when three different soils were amended with 0.05% biochar, the hemp plant showed total PFAS uptake of 90%, 14%, and 72%, whereas the OG species exhibited total PFAS uptake of 40%, 6%, and 14% from PI, AR, and KMVM soil, respectively. On the other hand, the uptake of total PFAS by TG species was 10%, 1%, and 12% from the same soils, respectively. The plants removed short-chain PFAAs more efficiently than long chains, and PFCAs were removed more effectively than PFSAs when the carbon chain length was the same. However, in this project, controls without biochar amendment were not established. Thus, it is unknown whether biochar at a minimum dose can truly exert a positive effect on the uptake of PFAS by the three plants. This will be addressed in the Phase Two application, as mentioned by Co-PI Lee Khan (May 20th, 2024, Zoom meeting). It should be noted that by the end of the growth period experiments, evaluating PFAS uptake by plant roots proved challenging due to the fibrous nature of tiny roots, resulting in inconsistent results for the analysis of PFAS concentrations in the roots of the plants. The analysis reports have been attached along with the summary, titled Final results of analysis of samples received on March 14, 2024. In the subsequent stage, a preliminary study was carried out for the second objective of this project. After the completion of plant growth experiments, 50% of the PFAS-laden biomass from all the plants was pyrolyzed to produce biochar and further analyzed for 28 PFAS residues in the synthesized biochar. The results indicated a non-detect down to 500 ppt (Minimum Reporting Level (MRL) = 500 ppt) for all 28 targeted PFAS, highlighting the potential of the pyrolysis method in breaking down the PFAS compounds. The soil amended with biochar should also be analyzed for PFAS at the end of the growth experiments to address whether the biochar can retain PFAS and release them back into the soil in the long term. Lee Khan provided the following information via email conversations with UAlbany: UAlbany has previously observed that in the case of liquefaction of PFAS-laden hemp plants, the degradation of PFAS by HTL was nearly 100% for carboxylic acids, but a portion of sulfonic acids remained. HTL also decreased precursor PFAS and extractable organic fluorine. The results are reported in the file titled Maine Laboratories Test Results. Overall, this study demonstrated that: 1) Biochar has the potential to increase the growth of all three selected plants. However, the exact effect depends on the soil type, plant species, and biochar dose; 2) Phytoremediation can be effective for removing short-chain PFAS in soil; 3) PFAS uptake rate and mass are highly dependent on the plant species, soil quality, biochar dose and type of PFAS; and 4) Complexity of the plant-soil-PFAS systems necessitates site-specific investigations to gather information, draw conclusions, and make recommendations tailored to each site. ?

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