Is In-Service Granular Activated Carbon Biologically Active? An Evaluation of Alternative Experimental Methods to Distinguish Adsorption and Biodegradation in GAC

In-service granular activated carbon (GAC) may transform into biological activated carbon (BAC) and remove contaminants through both adsorption and biodegradation, but it is difficult to determine its biodegradative capacity. One approach to understand the GAC biodegradative capacity is to compare t...

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Bibliographic Details
Published in:Environmental science & technology 2022-11, Vol.56 (22), p.16125-16133
Main Authors: Yuan, Jie, Fox, Fiona, Crowe, Grace, Mortazavian, Soroosh, Passeport, Elodie, Hofmann, Ron
Format: Article
Language:English
Subjects:
Activated carbon
Adsorption
Autoclaving
Biodegradation
Biodegradation, Environmental
Biological activity
Carbon
Charcoal
Contaminants
Experimental methods
Filtration - methods
Gamma irradiation
Irradiation
Microorganisms
Pollutant removal
Sodium
Sodium Azide
Sodium azides
Sterilization
Treatment and Resource Recovery
Water Pollutants, Chemical - metabolism
Water Purification - methods
γ Radiation
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Summary:In-service granular activated carbon (GAC) may transform into biological activated carbon (BAC) and remove contaminants through both adsorption and biodegradation, but it is difficult to determine its biodegradative capacity. One approach to understand the GAC biodegradative capacity is to compare the performance between unsterilized and sterilized GAC, but the sterilization methods may not ensure effective microbial inhibition and may affect adsorption. This study identified the 14C-glucose respiration rate as the best metric to evaluate the effectiveness of three sterilization methods: sodium azide addition, autoclaving, and γ irradiation. The sterilization protocols were refined, including continuously feeding 300 mg/L of sodium azide, three cycles of autoclaving, and 10–12 kGy of γ irradiation. Parallel minicolumn tests were conducted to identify sodium azide addition as the most broadly effective sterilization method with an insignificant effect on adsorption in most cases, except for the adsorption of anionic compounds under certain conditions. Nevertheless, this problem was solved by decreasing the azide dosage as long as it is still sufficient to provide effective microbial inhibition. This study helps to develop an approach that differentiates adsorption and biodegradation in GAC, which could be used by future studies to advance our understanding of BAC filtration.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.2c03639