Yanpeng Li 1,2, Haifeng Zhang1, Xionghui Qiu3, Yanru Zhang1, Huanran Wang 4
Received:
September 15, 2012
Revised:
February 27, 2013
Accepted:
February 27, 2013
Download Citation:
||https://doi.org/10.4209/aaqr.2012.09.0245
Cite this article:
Li, Y., Zhang, H., Qiu, X., Zhang, Y. and Wang, H. (2013). Dispersion and Risk Assessment of Bacterial Aerosols Emitted from Rotating-Brush Aerator during Summer in a Wastewater Treatment Plant of Xi’an, China.
Aerosol Air Qual. Res.
13: 1807-1814. https://doi.org/10.4209/aaqr.2012.09.0245
A microbial risk assessment was carried out for the rotating-brush aerator used during summer in a wastewater treatment plant (WWTP) of Xi’an, China. Bacterial aerosols were first collected by an Andersen cascade impactor at selected sampling sites near the rotating-brush aerator. The concentrations of airborne bacteria were used to obtain microbial emission rate by back calculation. The downwind concentrations of airborne bacteria were then calculated by a modified Gaussian dispersion model accounting for environmental impact and microorganism decay. Subsequently, the exposure parameters suitable for Chinese people were incorporated into a risk assessment model to evaluate non-carcinogenic risks of airborne mesophilic bacteria to sewage workers and surrounding residents. The results indicate that both mean bacterial concentrations at ground level and the exposure hazard quotient decrease rapidly with downwind distance. The exposure hazard quotient by inhalation route is over 105 times more than by dermal contact route for both children and adults, suggesting that inhalation route is the major exposure pathway of microbial aerosol intake for surrounding people. Although the present model gives acceptable low risk values at various downwind distances, it is worth noting that health risks of microbial aerosols associated with rotating-brush aeration for children are generally much more than those for adults.
ABSTRACT
Keywords:
Microbial aerosols; Dispersion; Risk assessment; Wastewater treatment plant; Rotating-brush aerator