Water treatment and wastewater treatment are the greatest engineering achievements of the 20th century in terms of public health. Wastewater systems have helped drastically reduce the incidence of enteric (gastrointestinal) disease, which remains a leading cause of childhood mortality in developing nations. The recent outbreak of Ebola virus disease has raised new concerns about the potential for exposure to the virus in wastewater, not only through direct contact but also through inhalation of aerosolized droplets. Prior work has shown that toilets, sewer systems, and wastewater treatment plants (WWTPs) can generate bioaerosols. It is often assumed that medical care in the developed world is superior to that in less developed areas, but there are certain technological aspects that may in fact lead to less desirable consequences. Research is needed in order to determine the extent to which Ebola virus could in fact be aerosolized by wastewater systems, from the point of use at a toilet to the sewer environment and ultimately in WWTPs. There are several critical knowledge gaps regarding the potential for aerosolization of Ebola virus from wastewater systems. Prior studies have not examined the aerosolization of filamentous viruses from wastewater systems, and even fundamental information, such as the size distribution and total number of aerosols generated from wastewater systems, is not available. Partitioning of microorganisms from human waste to liquid, aerosols, and surfaces in wastewater systems has not been considered. Additionally, it is not known whether Ebola virus is able to survive after being aerosolized from wastewater. Given the high mortality rate of Ebola virus disease and the many unanswered questions surrounding aerosolization from wastewater, this research is critical for ensuring the safety of workers who may come into contact with wastewater. Results from this project will support practical solutions, such as installing toilet lids or informing recommendations for safe work practices and use of personal protective equipment.
The overall goal of this research is to assess the potential for inhalation exposure to Ebola virus that is aerosolized during the regular operation and maintenance of wastewater systems. We will seed Ebola virus surrogates into three wastewater systems (flush toilets, a laboratory-scale sewer model, and a laboratory-scale aeration basin), quantify the amount aerosolized, and measure the size distribution of the carrier aerosols. Using this information, the PIs will predict the fate of the virus and the dose inhaled by nearby workers. The specific objectives are to (1) quantify the emission rate and size distribution of Ebola virus surrogates and total aerosols produced by wastewater systems; (2) determine the partitioning of Ebola virus surrogates between water, stool, and surfaces; (3) predict the fate of the aerosolized viruses and potential inhaled dose. This project will produce novel data about the number of aerosolized viruses and the size of the carrier aerosols produced by wastewater systems, including toilets, sewers, and aeration basins. Because aerosol size largely dictates fate in the atmosphere, this knowledge is critical for predicting the risk posed by aerosolization of Ebola virus from wastewater systems. While bioaerosol formation in sewers and WWTPs has been surveyed in the field, we will examine generation of bioaerosols for the first time under controlled laboratory conditions. This project will also produce novel information about the partitioning of an enveloped virus between water, solids, and surfaces in wastewater systems. Finally, this project will provide the first quantitative estimate of the potential for inhalation exposure to Ebola virus that is aerosolized during the regular operation and maintenance of wastewater systems.
