PFAS Characteristics and Treatment for Landfill Leachate
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-02-21 |
| Journal | Highlights in Science Engineering and Technology |
| Authors | Boting Chen |
| Institutions | University of Florida |
| Citations | 1 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis paper analyzes the characteristics of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) in landfill leachate and evaluates advanced remedial technologies for their removal and destruction.
- PFAS Challenge: Landfill leachate is a significant source of highly persistent, mobile PFAS (primarily short-chain PFAAs like PFOA and PFOS), posing a substantial environmental risk due to their non-degradability.
- Adsorption Efficacy: Activated Carbon (AC) remains a highly efficient physical removal method for long-chain PFAS, achieving 90% to 99% removal in contaminated water and >97% removal of PFOA in bench-scale leachate tests.
- Foam Fractionation (FF): FF is a sustainable physical alternative, demonstrating high removal (up to 99%) of terminal PFAS, though its efficiency is lower (<80%) for complex precursor compounds found in leachate.
- Advanced Oxidation (AOP): Chemical degradation is essential for destruction. Gallium oxide (Ga2O3) photocatalysis achieved 100% PFOA removal in 1.5 hours under optimal acidic conditions (pH 3).
- Electrochemical Destruction: Boron-Doped Diamond (BBD) anodes show great potential for full-scale application, achieving approximately 80% destruction of PFOA and PFOS in complex leachate due to the BBD materialâs durability and strong oxidative power.
- Future Strategy: A combination of treatment methods (e.g., AC adsorption for bulk removal followed by BBD oxidation for destruction) is recommended as a feasible, environmentally and economically sound solution.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes key performance data extracted from the remediation studies discussed in the paper.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| PFOA Removal (AC) | 90 to 99 | % | Groundwater treatment [8] |
| PFOA Removal (AC + Fe) | >97 | % | Bench-scale leachate treatment [9] |
| PFOS/PFOA Recovery (FF) | Up to 99 | % | Optimized with 11.5 mM Ferric Iron [14] |
| PFOA Degradation Time (Ga2O3) | 1.5 | hours | 100% removal achieved at optimal pH [16] |
| Optimal pH (Ga2O3 Oxidation) | 3 | - | Acidic condition for PFOA destruction [16] |
| Terminal PFAS Removal (FF) | ≥90 | % | Landfill leachate analysis [15] |
| Precursor PFAS Removal (FF) | <80 | % | Landfill leachate analysis [15] |
| PFOA Removal (Electrochemical) | 96 | % | Concentrated waste streams [17] |
| PFOS Removal (Electrochemical) | 99 | % | Concentrated waste streams [17] |
| PFOA/PFOS Removal (BBD Anodes) | ~80 | % | Landfill leachate treatment [20] |
Key Methodologies
Section titled âKey MethodologiesâThe primary methodologies explored for PFAS removal and destruction from landfill leachate include physical separation and chemical/electrochemical degradation.
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Activated Carbon (AC) Adsorption:
- Mechanism: Hydrophobic contact and electrostatic interactions are utilized to bind PFAS molecules to the high-porosity carbon surface.
- Parameters Studied: The effect of temperature (higher temperature increased adsorption), pH, and competition from other contaminants (e.g., phosphate) were examined using both Powdered AC (PAC) and Granular AC (GAC) [11].
- Enhancement: Bench-scale tests showed improved PFOA removal when AC was combined with Fe (iron) [9].
-
Foam Fractionation (FF):
- Mechanism: Adsorptive bubble separation relies on the amphiphilic nature of PFAS, which concentrate at the air-water interface of generated bubbles.
- Optimization: Efficiency was maximized by adding metallic activators, specifically 11.5 mM of ferric iron (Fe3+), with performance being sensitive to lower pH conditions [14].
-
Chemical Oxidation (Gallium Oxide):
- Process: Advanced oxidation using highly reactive gallium oxide (Ga2O3) photocatalysis, often assisted by peroxymonosulfate (PMS) and UV light.
- Conditioning: The PFOA destruction process was highly dependent on pH, achieving optimal performance in acidic conditions (pH 3) [16].
-
Electrochemical Anodic Oxidation (Boron-Doped Diamond - BBD):
- Electrode Material: BBD anodes were selected for their unique properties: extreme durability, resistance to corrosion, and high overpotential, which facilitates the generation of powerful hydroxyl radicals for C-F bond cleavage.
- Application: Tested successfully on both concentrated waste streams and complex landfill leachate. Further studies explored the addition of zinc anodes to enhance the degradation of long-chain PFAS [18, 20].
Commercial Applications
Section titled âCommercial ApplicationsâThe technologies discussed are critical for environmental engineering and materials science sectors focused on persistent pollutant remediation.
- Wastewater Treatment Infrastructure: Implementation of full-scale adsorption systems (GAC/PAC) and advanced oxidation reactors for municipal and industrial wastewater treatment plants (WWTPs) handling landfill leachate.
- High-Performance Electrode Manufacturing: Commercial production of Boron-Doped Diamond (BBD) electrodes for electrochemical reactors, leveraging the materialâs stability and high oxidative power for PFAS destruction.
- Water Remediation Services: Specialized services offering mobile or fixed-base Foam Fractionation (FF) units for groundwater and leachate cleanup, focusing on cost-effective physical separation of terminal PFAS.
- Catalyst and AOP System Development: Design and deployment of advanced oxidation systems utilizing novel catalysts (e.g., Ga2O3) and UV/PMS activation for complete destruction of recalcitrant organic pollutants.
- Environmental Materials Recycling: Development of processes for the regeneration and safe disposal of spent adsorbent materials (AC) saturated with highly toxic PFAS compounds, potentially involving high-temperature incineration or solvent extraction (e.g., methanol).
View Original Abstract
Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are manmade chemicals which has been extensively used, resulting in great potential for human and environmental accumulation due to high persistence. PFASs can be divided to two parts, terminal and precursor compounds, based on how many fluorine atoms link to the carbon bonds. Many studies have examined the removal ability of method including activated carbon (AC), Foam fractionation (FF), chemical oxidation and boron-doped diamond anodes (BBD). This paper focus on introducing advanced remedial technology for PFAS treatment from landfill leachate. The details about PFASs are introduced, including the chemical structure, source, and properties. Then, different types of PFASs from landfill leachate are demonstrated. Some of PFAS, especially short-chain, are prone to stay as liquid phase. Activated carbon, a great model of adsorption, shows excellent performance on removal of PFOS and PFOA. In addition, boron-doped diamond anodes technique which belongs to the electrochemical anodic oxidation, have a great potential on landfill leachate in the future. Last but not least, the conclusion makes a summary and shows possible treatment to landfill in the future.