Electro-oxidation treatment of sewage water using mixed metal oxide anodes for microbial decontamination

Abstract

Electrochemical technologies provide an alluring decentralized wastewater treatment system to remove microbial load from contaminated water. The mixed metal oxide (MMO) anodes used for this electrooxidation (EO) technology are stable due to the presence of titanium, ruthenium, iridium, and platinum oxides. This EO technology works by passing current in the presence of minimum electrolyte concentration, sufficient to kill the bacteria present in sewage and simulated water. This technology can be used in sewage pre-treatment plants so that the microbes present in sewage water will not come into the environment, thus, preventing the spread of an epidemic. The lab-scale electrochemical disinfection experiments were performed under batch conditions to see the inactivation efficacy of the EO system with eight different bacteria (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Salmonella enterica, Acinetobacter calcoacetius, Serratia marcescens, Listeria sp., Enterococcus faecalis). The results showed that at an optimized condition of current density (2.38 mA/cm2), NaCl concentration (1 g/300 mL), treatment time (2 min), 100% inactivation of all the eight bacteria in simulated water was achieved. Under the same optimized conditions, 100% inactivation was achieved with actual sewage water with a treatment time of 8 min. Further, potassium ion leakage and vital staining tests were performed to confirm the complete inactivation of bacteria. The electrodes used in this study were durable even after 80 cycles, as demonstrated through FE-SEM/EDS, XRD, and Raman spectra. Thus, this developed EO system with inexpensive MMO electrodes would open up new channels in treating waterborne epidemics, especially in healthcare facilities.