Comparative Disinfection of Indicator Bacteria and Poliovirus by Chlorine Dioxide

The effectiveness of ClO₂ to disinfect poliovirus and indicator bacteria in clean water and sewage was determined. Clostridiumperfringens was the most resistant to disinfection by ClO₂, followed by poliovirus, s. faecalis (fecal streptococcus) and E. coli (fecal coliform). These results suggest that reduction in concentrations of C. perfringens. but not fecal coliform or fecal streptococcus, can be used as a simple monitoring assay to determine if ClO₂ treatment conditions to disinfect human enteric viruses had been achieved. In sewage effluent a small and variable fraction of fecal coliform and fecal streptococcus were highly resistant to disinfection by ClO₂ and often persisted longer than the measurable levels of poliovirus. This resistant fraction of indicator bacteria was determined to be associated with particulate matter which protected the bacteria from disinfection.