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Proceedings available at: http://www.extension.org/67742
A study was conducted to evaluate the pathogen inactivation on 9 dairy facilities in Wisconsin with a combination of anaerobic digestion and solid/liquid separation technologies. Samples were collected every 2 weeks over the course of eight months to assess dairy pathogen inactivation in full-scale operational digesters and solid/liquid separators. Samples were then analyzed by qPCR for pathogens including protozoa, bacteria. bovine viruses, and indicators.
Preliminary results indicate full-scale anaerobic digesters reduce pathogen levels by 99% to 99.9%. And after digestion and separation of the digestate, the liquid fraction contains the majority of pathogens. Although the solids fraction contained fewer pathogens, the concentration could still be above the infectious dose, particularly for calves. Results have implications for a variety of digestate end uses including bedding and land spreading.