Student Research: Gabriela Depavia
Pathogenic microorganisms are known to be present throughout the Wastewater Treatment (WWT) process. These microorganisms are found not only in the wastewater and sludge, but also in aerosols which are generated throughout the treatment process. Hence, WWT workers are potentially exposed to a variety of infectious agents from both contact of contaminated surfaces and aerosolized wastewater. Previous studies suggest that WWT workers have higher incidents of a number of symptoms and diseases. However, most of these studies did not qualitatively or quantitatively determine the etiologic agents. The objective of this study was to determine the potential exposure to microbial pathogens at various stages of the WWT process. The approach was to determine microbial load at each stage of the WWT process. Wastewater, sludge, and air samples were collected at different sites of the treatment plant including the bar screen, primary sedimentation basins, secondary sedimentation basin, sludge handling building (gravity belt room), sludge loading dock, and office. In addition, air samples were also taken in a wastewater pump station. After collection, the concentration of total plate count, Gram-negative counts and fecal coliform counts were determined in the air samples. The wastewater and air samples were also analyzed for the presence of a selected list of microbial pathogens using the polymerase chain reaction method. Results of this study showed that gastrointestinal and respiratory pathogens are present in the wastewater and/or air at different phases of the WWT process. In addition, the highest concentrations of microorganisms in the wastewater and in the air were found at the gravity belt room and at the bar screen room. The high concentration of microorganisms in the wastewater and air, and the presence of pathogens throughout the system pose a potential risk for adverse health effects in WWTP workers.