Submitted to: Recycling of Agricultural Municipal and Industrial Residues
Publication Type: Proceedings
Publication Acceptance Date: May 1, 2001
Publication Date: May 14, 2002
Citation: Vanotti, M.B., Millner, P.D., Hunt, P.G., Ellison, A.Q. 2002. Destruction of pathogens in liquid swine manure by biological nitrogen removal and phosphorus treatment. In: Proceedings of the Recycling of Agricultural Municipal and Industrial Residues in Agriculture 10th International Conference Hygiene Safety, May 14-18, 2002, Slovak Republic. p. 31-35. Technical Abstract: Concern has greatly increased about the potential for contamination of water, food, and air by pathogens present in manure, byproducts, and bioaerosols. We evaluated pathogen reduction in a multistage system where first the solids and liquid in swine manure are separated with polymer, followed by biological N removal using nitrification and denitrification and then P extraction through lime precipitation. Each step of the treatment system was evaluated for its effectiveness in reducing pathogens by counting total and fecal coliforms, enterococci, and salmonellae on selective and differential nutrient media. Before treatment, concentrations of total and fecal coliforms were 1.10 x 10**7 colony forming units (cfu)/mL and 1.28 x 10**6 cfu/mL, respectively. Enterococci concentration was 9.52 x 10**5 cfu/mL and salmonella concentration was 2.3 x 10**4 cfu/mL. Results showed a consistent trend in reduction of pathogens as a result of each step in the treatment system. Solids separation reduced 67 to 83% of the pathogens compared with 98% removal of volatile suspended solids in the same process step. Biological N removal with alternating anoxic and oxic conditions destroyed a large amount of the microbes with total reductions of 5 logs (99.997%) for total coliforms, 4 logs for fecal coliforms and enterococci, and 2 logs for salmonellae. Salmonellae and pathogen indicators were eliminated with the phosphorus treatment in the sequence due to elevated pH (10.3); there were no colonies to count at the upper threshold limit value of <3 x 10**1 cfu/mL. Our results indicate that nitrification/denitrification treatment is very effective in reducing pathogens in liquid swine manure and that the phosphorus removal step via calcium precipitation produces a sanitized effluent which may be important for biosecurity reasons.