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Looking beyond Sorption in GAC Filters: How Extended Contact Times and Functionally Distinct Microbial Biomass Enable
Sema Karakurt-Fischer1, Janek Greskowiak2, Kathrin Fenner1,3
1Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf 8600, Switzerland.
Environmental Science & Technology
|July 1, 2026
Summary
Granular activated carbon (GAC) filters enhance micropollutant removal through biodegradation, not just sorption. GAC
Area of Science:
- Environmental Engineering
- Water Treatment
- Environmental Chemistry
Background:
- Micropollutant abatement in granular activated carbon (GAC) filters involves sorption and biodegradation.
- Limited understanding exists regarding which micropollutants biodegrade, the extent of biodegradation's contribution, and GAC's influence on this process.
Purpose of the Study:
- To investigate the fate of 45 micropollutants in GAC and sand filters.
- To quantify the role of biodegradation in micropollutant removal by GAC.
- To elucidate how GAC properties affect biodegradation processes.
Main Methods:
- Combined reactive transport modeling with pilot-scale experiments.
- Investigated 45 micropollutants in parallel GAC and sand filters up to 100 min contact times.
- Utilized tracer tests to determine solute-biomass contact times.
Main Results:
- GAC's intragrain porosity (40%) extended solute-biomass contact times by 1.7x compared to sand.
- Enhanced abatement observed for 25 of 45 micropollutants at contact times >25 min, indicating biodegradation.
- Biotransformation products confirmed biodegradation of diclofenac, venlafaxine, and hydrochlorothiazide exclusively in GAC.
Conclusions:
- GAC facilitates biodegradation of more micropollutants (24) than sand (16), irrespective of sorption affinity.
- Intragrain porosity in GAC is crucial for prolonging contact times, benefiting the biodegradation of less sorptive compounds.
- GAC supports distinct microbial communities capable of unique biotransformations compared to sand.
Keywords:
biodegradationconservative and reactive solute transfer modelingmicropollutant abatementporous media filtrationsolute contact timesorptionMore Related Videos
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