Characteristics and exposure risks of potential pathogens and toxic metal(loid)s in aerosols from wastewater treatment plants

Abstract

Aerosols from wastewater treatment plants (WWTPs) are considered to be potentially hazardous to on-site employees and surrounding residents. However, their harmful components and their effects remain poorly understood. In this study, the characteristics, responsible factors, sources and exposure risks of potential pathogens and toxic metal(loid)s in aerosols from four WWTPs were investigated. There were 21 potential pathogens and 15 toxic metal(loid)s detected in the aerosols. Arcobacter and Fe were the dominant taxa responsible for the dissimilarity of the potential pathogen population and toxic metal(loid) composition between the aerosols and the wastewater/sludge, respectively. Both meteorological factors and sources affected pathogen and toxic metal(loid) composition. The potential pathogens and toxic metal(loid)s in indoor aerosols mainly originated from wastewater/sludge, while those in outdoor aerosols originated from wastewater/sludge and ambient air. The highest respirable fraction (<3.30 μm) concentrations and proportions were detected at the aeration units. Non-carcinogenic and carcinogenic risks of toxic metal(loid)s for both adults and children were found within and/or around WWTPs, and non-carcinogenic risks of bacteria for children were found at downwind, suggesting the need for active safeguard procedures, such as that employees wear masks and work clothes, covering the main emission sites, and collecting and destroying of aerosols.