Site Specific Risk Assessment Tools for Land Applied Biosolids

Abstract

This project compiled information on the fate, transport, and risk presented by pathogens in land-applied biosolids into a spreadsheet based risk assessment model. The model was applied to an example field. This report describes the integration of knowledge to assess microbial risks from the land application of biosolids. This knowledge has been incorporated into an environmental dispersion, exposure, and risk model, known as the Spreadsheet Microbial Assessment of Risk: Tool for Biosolids (“SMART Biosolids”). The SMART Biosolids model includes a user's manual that enables wastewater utilities, land applicators, and regulators, to estimate microbial risk from biosolids land application under a variety of scenarios and thereby gain insight into effective management practices. In addition, this project conducted field monitoring to assess the fate and transport of microbes from land application during wet weather events. The field monitoring did not find detectable quantities of pathogens after transport through several feet of soil in the field. However, the study did quantify some desorption of pathogens and indicators into ponded surface water, suggesting that runoff from biosolids amended fields may have trace amounts of pathogens. The risk assessment model was applied to quantify the risks such runoff might pose to surface waterbodies on a site-specific basis. The example scenarios run suggest that microbial risk due to contamination of surface waters from land application runoff would be below existing risk standards for recreational surface waters. The risk modeling estimated that exposure due to the incidental ingestion of soil appears to be the pathway of most concern and adenovirus was found to be the organism presenting the highest risk over the different pathways considered. Adenovirus is a common pathogen that is not associated with life threatening illness. The results are based on extremely limited monitoring for adenovirus (N=5). An important goal of knowledge integration efforts such as this is to identify and help prioritize knowledge gaps. The need for better information on the occurrence and persistence of adenovirus in land-applied biosolids is a key research need identified by this study. This title belongs to WERF Research Report Series . ISBN: 9781843392590 (eBook)