Quantification of Airborne Biological Contaminants Associated with Land-Applied Biosolids

Greater than 50% of all class B biosolids produced in the US are reused by application to agricultural land. The goal of this research was to pair a comprehensive literature review with a field aerosol sampling campaign to characterize aerosols emitted during the land application process and provide a simplified framework for evaluating exposure to on-site workers and off-site residents. Three aerosolization scenarios for dewatered biosolids were considered and include spreading biosolids onto land by side slinging, disk incorporating into soils, and aerosolization of land applied biosolids due to high wind events. Particulate mater, metal aerosols, and biological aerosols of biosolids origin were in the respirable size range and were markedly greater downwind of land application than in upwind ambient control sites. Low level aerosolization of field applied biosolids were detected during high wind events, and biosolids derived aerosols were detected at 170 meters downwind of disk incorporation. 
The ability to reconstruct source aerosol concentration from PM10 measurements and the linear correlations made between bulk biosolids concentrations and source emission rates serve as a framework for determining relevant aerosol concentrations without the requirement of biological or chemical aerosol sampling. Application of this framework eliminates the inherent limitations and costs associated with monitoring low aerosol concentration of toxic compounds and pathogens. 
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