Application of Photodynamic Oxidation to the Disinfection of Tapwater, Sea Water, and Sewage Contaminated With Poliovirus

Poliovirus when added to tapwater, sewage or seawater was readily photoinactivated by methylene blue and visible light. Typically, almost 2.5 logs of virus could be inactivated upon a 5‐min exposure to 670 nm light (20 W/m 2 ) in solutions containing 13 μ M methylene blue at pH 10.0. A biphasic inactivation curve was produced for poliovirus, regardless of dye concentration, pH, temperature, sensitization time, nature of suspending solution or sequence of light exposure. These results indicated that a multi‐hit inactivation event was occurring. Preincubation of the dye‐virus mixture at 24°C increased the rate of virus photoinactivation. Dye concentrations above 26 μ M have little advantage in increasing the amount of virus photoinactivated. Significant inactivation of the virus in the dark occurred at high dye concentrations (52–130μ M ).