ARS | Publication request: PAM and manure liquid-solids separation and nutrient management

Submitted to: Soil and Water Conservation Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 15, 2002
Publication Date: July 15, 2002
Citation: Vanotti, M.B. 2002. PAM and manure liquid-solids separation and nutrient management [abstract]. Soil and Water Conservation Society 2002 Annual Conference, July 13-17, 2002, Indianapolis, Indiana.

Technical Abstract: The continued trend towards fewer but larger operations means that more manure nutrients are being generated within relatively small areas. This spatial distribution problem could be solved if the solids are separated from the liquid phase and moved short distances, mostly within a county. The challenge is that most of the organic nutrient elements ( nitrogen and phosphorus) in manure are contained in very fine suspended particles (<0.3 mm) that are not separated by mechanical separators. Polyacrylamide (PAM) polymers offer a solution to this problem because they increase separation of suspended and colloidal solids and therefore capture the nutrients contained in the small particles. PAM action is by binding together the small particles into larger particles (flocs) that separate from the liquid and dewater more readily. The treatment is more efficient when liquid strength is higher. Various filter materials such as screens, filter presses, filter belts, and sand filters have been successfully used for dewatering flocculated manure. In general, PAM treatment can provide separation efficiencies higher than 90% for total suspended solids, volatile suspended solids, and organic P and N. This treatment also increases the N:P ratio of the effluent from about 5 to 12, which results in a more balanced effluent for nutrient needs. Thus, the treated liquid can be land applied with reduced risk of accumulating P in the soil. Transport of solids and treatment and handling of remaining liquid are made easier, with accompanying implications for improved management of nutrients in areas where animal production is concentrated.