Land Application of Biosolids and the Concentration of Pathogens in Aerosol Form - Reaserch Proposal
The research proposal for this group will help advance the risk assessment of exposure to pathogens, or viruses, such as Salmonella and Coxackie, from the land application of biosolids. Biosolids, stabilized sewage sludge, can be used as a soil amendment/fertilizer but are also disposed of when land application uses are not available or accessible, and too costly. When land applied, biosolids are generally used in four forms: as a rich, moist soil amendment, dried pellet, liquid, or compost. Class A biosolids are essentially free of pathogens prior to land application. The metal contents requirements under the Part 503 Rule are the same for Class A and Class B biosolids. Class B biosolids may have low levels of pathogens. This research is focusing on the Class B biosolids only.
The study is looking at the land application of biosolids from a tractor onto a field. The study will have a receptor downwind of the tractor while the application is taking place that measures the amount of aerosol exposure. This is to focus on the maximum exposure to help set parameters for minimum distances for homes from the application site and will help make recommendations for regulatory policy. The research will help to form a user-friendly spreadsheet to help local areas to modify using their own conditions.
My research aspect has been to verify that our model can reproduce the results from the study by Swee Yang Low reported in the article “Off-Site Exposure to Respirable Aerosols Produced during the disk-Incorporation of Class B Biosolids.” I am using the spreadsheet model that the study is developing to match what the Low study observed. The data given in the Low study identified a few parameters; tractor speed, area of the plot, height of the receptor, the distances from the applicator at which the measurements were taken, and the average wind speeds. The other parameters must be fixed or assumed and are variables that must be adjusted to fit the data. The spreadsheet model is using the Gaussian Plume Model with a dispersion equation and will compare the application and concentration over time. As time permits, our model will use other field data sets to reproduce results from additional studies. Using additional field data as support for the model will aid in verifying our developed spreadsheet model.