Sequential electrocoagulation-electrooxidation for virus mitigation in drinking water

Electrochemical water treatment is a promising alternative for small-scale and remote water systems that lack operational capacity or convenient access to reagents for chemical coagulation and disinfection. In this study, the mitigation of viruses was investigated using electrocoagulation as a pretreatment prior to electrooxidation treatment using boron-doped diamond electrodes. This research is the first to investigate a sequential electrocoagulation-electrooxidation treatment system for virus removal. Bench-scale, batch reactors were used to evaluate mitigation of viruses in variable water quality via: a) electrooxidation, and b) a sequential electrocoagulation-electrooxidation treatment train. Electrooxidation of two bacteriophages, MS2 and ΦX174, was inhibited by natural organic matter and turbidity, indicating the probable need for pretreatment. However, the electrocoagulation-electrooxidation treatment train was beneficial only in the model surface waters employed. In model groundwaters, electrocoagulation alone was as good or better than the combined electrocoagulation-electrooxidation treatment train. Reduction of human echovirus was significantly lower than one or both bacteriophages in all model waters, though bacteriophage ΦX174 was a more representative surrogate than MS2 in the presence of natural organic matter and turbidity. Compared to conventional treatment by ferric salt coagulant and free chlorine disinfection, the electrocoagulation-electrooxidation system was less effective in model surface waters but more effective in model groundwaters. Sequential electrocoagulation-electrooxidation was beneficial for some applications, though practical considerations may currently outweigh the benefits.