Effect of Electrode Type on Bacteria Removal and Chlorine and Radical Production in Electrochemical Water Disinfection

Abstract

Formation and contamination of malicious microorganisms and viruses remain to be major problem of water resources. This is mostly due to the fact that, groundwater, which constitutes a large share of available fresh water content, is prone to contamination from urban and industrial wastes. In this work, electrochemical treatment is considered as a disinfection mechanism. The literature presents several cases of individual of electrochemical disinfection experiments. In this particular work, we aim to focus on the comparative disinfection efficiency of Boron-doped diamond electrodes, Iridium metal-oxide electrodes and Graphite plate electrodes at various electrochemical settings, whilst monitoring formation of toxic bi-products, such as chlorine and other radicals. Experiments of electrochemical water disinfection were carried out on real groundwater samples deliberately contaminated with E. coli culture. During the reaction, microorganisms die due to both direct physical damage and due to the electrochemically generated radicals. Therefore, there is a gentle balance of bacteria elimination versus avoiding excessive radical production in the treated water. Since the biological behaviour of the microorganisms and the chemical properties of the available groundwater cannot be changed, the research parameters boil down to experimenting through various popular electrode types and electrical current settings. In both continuous-flow and recursive systems, the Boron-doped diamond electrodes are observed to provide desirable level of disinfection (as good as Iridium metal-oxide), while yielding lower radicals (as low as those of Graphite-plate), making an ideal compromise for the process.