Abstract
Unlike many other water disinfection methods, hydroxyl radicals (HO•) produced by the Fenton reaction (Fe2+/H2O2) can inactivate pathogens regardless of taxonomic identity of genetic potential and do not generate halogenated disinfection by-products. Hydrogen peroxide (H2O2) required for the process is typically electrogenerated using various carbonaceous materials as cathodes. However, high costs and necessary modifications to the cathodes still present a challenge to large-scale implementation. In this work, we use granular activated carbon (GAC) as a cathode to generate H2O2 for water disinfection through the electro-Fenton process. GAC is a low-cost amorphous carbon with abundant oxygen- and carbon-containing groups that are favored for oxygen reduction into H2O2. Results indicate that H2O2 production at the GAC cathode is higher with more GAC, lower pH, and smaller reactor volume. Through the addition of iron ions, the electrogenerated H2O2 is transformed into HO• that efficiently inactivated model pathogen (Escherichia coli) under various water chemistry conditions. Chick–Watson modeling results further showed the strong lethality of produced HO• from the electro-Fenton process. This inactivation coupled with high H2O2 yield, excellent reusability, and relatively low cost of GAC proves that GAC is a promising cathodic material for large-scale water disinfection.
Highlights
IntroductionTo minimize the likelihood of contamination, drinking water is typically treated using a multi-barrier approach including disinfection and maintenance of a disinfectant residual during distribution of drinking water to the consumers
The burden of waterborne pathogens is significant and can lead to severe health complications [1,2].To minimize the likelihood of contamination, drinking water is typically treated using a multi-barrier approach including disinfection and maintenance of a disinfectant residual during distribution of drinking water to the consumers
Through the addition of iron ions, the electrogenerated H2 O2 is transformed into HO that efficiently inactivated model pathogen (Escherichia coli) under various water chemistry conditions
Summary
To minimize the likelihood of contamination, drinking water is typically treated using a multi-barrier approach including disinfection and maintenance of a disinfectant residual during distribution of drinking water to the consumers. Most commonly used disinfection methods include ozonation, chlorination, chloramination, UV irradiation, and their combinations [3,4,5]. While each of these methods can be effective, they have key limitations. Chlorination can result in formation of carcinogenic disinfection byproducts (DBP) [8], which may require pre-chlorination approaches to minimize DBP formation and additional significant efforts to manage post-chlorination DBP concentrations [9]. UV irradiation kills microorganisms by damaging double-stranded DNA [10,11], but this strategy is ineffective in turbid conditions; cells might reverse the DNA damage through a repair mechanism [12,13,14]
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