Pathogen Control in Liquid Swine Manure Using Advanced Treatment in Usa

The usefulness of composting, heat drying, and alkaline stabilization treatment processes to destroy infectious microorganisms contained in solid manure and biosolids in general is well known. However, little is known about rates of pathogen reduction during treatment of liquid manure and livestock wastewater effluents. We evaluated pathogen reduction in liquid swine manure in a multistage system where first the solids and liquid are separated with polymer, followed by biological nitrogen 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. Results indicated 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.