Evaluation of pathogen disinfection efficiency of electrochemical advanced oxidation to become a sustainable technology for water reuse

Water treatment , reuse is gaining acceptance as a strategy to fight against water contamination and scarcity, but it usually requires complex treatments to ensure safety. Consequently, the electrochemical advanced pro-cesses have emerged as an effective alternative for water remediation. The main objective here is to perform a systematic study that quantifies the efficiency of a laboratory-scale electrochemical system to inactivate bacteria, bacterial spores, protozoa, bacteriophages and viruses in synthetic water, as well as in urban wastewater once treated in a wetland for reuse in irrigation. A Ti|RuO2-based plate and Si|BDD thin-film were comparatively employed as the anode, which was combined with a stainless-steel cathode in an undivided cell operating at 12 V. Despite the low resulting current density (<15 mA/cm2), both anodes demonstrated the production of oxi-dants in wetland effluent water. The disinfection efficiency was high for the bacteriophage MS2 (T99 in less than 7.1 min) and bacteria (T99 in about 30 min as maximum), but limited for CBV5 and TuV, spores and amoebas (T99 in more than 300 min). MS2 presented a rapid exponential inactivation regardless of the anode and bacteria showed similar sigmoidal curves, whereas human viruses, spores , amoebas resulted in linear profiles. Due the different sensitivity of microorganisms, different models must be considered to predict their inactivation kinetics. On this basis, it can be concluded that evaluating the viral inactivation from inactivation profiles determined for bacteria or some bacteriophages may be misleading. Therefore, neither bacteria nor bacteriophages are suitable models for the disinfection of water containing enteric viruses. The electrochemical treatment added as a final disinfection step enhances the inactivation of microorganisms, which could contribute to safe water reuse for irrigation. Considering the calculated low energy consumption, decentralized water treatment units powered by photovoltaic modules might be a near reality.

Automated summary

Water treatment and reuse have gained acceptance as effective strategies to combat water contamination and scarcity. Electrochemical advanced processes have emerged as a viable alternative for water remediation, offering efficient disinfection of microorganisms. The study aimed to quantify the efficiency of a laboratory-scale electrochemical system in inactivating various microorganisms in synthetic water and urban wastewater. The use of Ti|RuO2-based plate and Si|BDD thin-film as anodes, combined with a stainless-steel cathode, resulted in the production of oxidants and high disinfection efficiency for bacteria and bacteriophages. However, the efficiency was limited for certain microorganisms such as spores and amoebas. Different models must be considered to predict the inactivation kinetics based on the sensitivity of microorganisms.