Bacillus thuringiensis (BT) spores and B. anthracis Sterne (BA) spores were used to investigate the effectiveness of electrochemical disinfection processes using different solution and operational conditions. We tested several anode materials for disinfection and found that the most efficient material was the quaternary metal oxide (TiO2-Sb2O5-Sn)2-RuO2). An open free gassing cell was used in the batch and flow configurations to test the quaternary oxide anodes for disinfection. The flow configurations had the advantage of a more stable operation compared to the batch methods that resulted in gradual heat buildup and electrolyte pH decrease. The solution composition and current density were varied to achieve the optimal disinfection conditions. The presence of sodium chloride at low concentrations (in the range from 1mM to 5mM) was found to be critical for the effective disinfection of BT spores. Active chlorine was produced in-situ by anodic oxidation chloride content at the anode. Moreover, soluble chlorine species, produced in-situ electrochemically resulted in chlorine residual that continued to kill spores after passage through the EC cell. Local tap water was used as a realistic test solution to measure disinfection of the BT spores. Scanning electronic images of the EC treated spores indicate damage to the outer membranes resulting in disruption and leakage of the spore contents. Electrochemical (EC) water disinfection using inexpensive electrode materials and water (with low levels of either native or introduced chloride ions) could serve as a viable alternative technology to chlorination or ozonation against difficult to disinfect biological threats.
Citation: Water Research
Pub Type: Journals
driking water disinfection, bacillus spores, electrochemistry, quaternary oxide electrodes