Disinfection of Ebola Virus in Sterilized Municipal Wastewater

Concerns have been raised regarding handling of Ebola virus contaminated wastewater, as well as the adequacy of proposed disinfection approaches. In the current study, we investigate the inactivation of Ebola virus in sterilized domestic wastewater utilizing sodium hypochlorite addition and pH adjustment. No viral inactivation was observed in the one-hour tests without sodium hypochlorite addition or pH adjustment. No virus was recovered after 20 seconds (i.e. 4.2 log10 unit inactivation to detection limit) following the addition of 5 and 10 mg L-1 sodium hypochlorite, which resulted in immediate free chlorine residuals of 0.52 and 1.11 mg L-1, respectively. The addition of 1 mg L-1 sodium hypochlorite resulted in an immediate free chlorine residual of 0.16 mg L-1, which inactivated 3.5 log10 units of Ebola virus in 20 seconds. Further inactivation was not evident due to the rapid consumption of the chlorine residual. Elevating the pH to 11.2 was found to significantly increase viral decay over ambient conditions. These results indicate the high susceptibility of the enveloped Ebola virus to disinfection in the presence of free chlorine in municipal wastewater; however, we caution that extension to more complex matrices (e.g. bodily fluids) will require additional verification.
Author Summary Ebola virus infected individuals may generate up to nine liters of potentially infectious liquid waste per day. Previous recommendations were to directly dispose of this waste into a sanitary sewer or latrine; however, release of infectious virus raised the concern of environmental transmission through unintentional contact with contaminated wastewater. One possibility to reduce or eliminate the release of infectious virus is disinfection of Ebola virus contaminated liquid waste. A hurdle to making recommendations for liquid waste disinfection is the lack of data on disinfection efficacy. Here we demonstrate that Ebola virus in municipal wastewater is highly sensitive to disinfection in the presence of free chlorine. In addition, elevating the pH to 11.2 significantly increased the rate of decay over neutral pH conditions. These results provide a basis to develop recommendations for the disinfection of Ebola virus contaminated wastewater.