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United States Department of Agriculture

Agricultural Research Service

Title: Dewatering of Phosphorus Extracted from Liquid Swine Waste

Authors
item Szogi, Ariel
item Vanotti, Matias
item Hunt, Patrick

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 2, 2005
Publication Date: September 12, 2005
Citation: Szogi, A.A., Vanotti, M.B., Hunt, P.G. 2005. Dewatering of phosphorus extracted from liquid swine waste. Bioresource Technology 97:183-190.

Interpretive Summary: Phosphorus (P) recovery from liquid swine manure is an attractive technology when on-farm application of liquid swine manure is not an option. We developed a technology that recovers this P, but its high moisture content makes transportation difficult. We investigated dewatering procedures to concentrate the P product. Sludge with high P content was obtained using a field prototype and further dewatered using a combination of flocculation treatment and filter bags. The flocculation treatment was effective to thicken P-rich sludge which enhanced filtration and dewatering. Without flocculation, filtration was incomplete due to clogging of filters. Filter bags retained more than 99 percent of suspended solids and total P. Solids content increased from about 1.5 percent to more than 90 percent. These dewatered solids can be transported more economically off the farm for use as a valuable fertilizer material.

Technical Abstract: Phosphorus (P) recovery from liquid swine manure is an attractive technology when on-farm application of liquid swine manure is not an option. We developed a technology that recovers this P, but its high moisture content makes transportation difficult. In this work, we investigated dewatering procedures to concentrate the P product. High grade calcium phosphate sludge (more than 20 percent P2O5) was obtained using a field prototype and further dewatered using a combination of polymer treatment and filter bags. Anionic polyacrylamide polymer treatment (20 mg/L or higher) was effective to flocculate P-rich sludge which enhanced filtration and dewatering. Without polymer, filtration was incomplete due to clogging of filters. Non-woven polypropylene and monofilament filter bag fabrics with mesh size smaller than 200 µm retained more than 99 percent of suspended solids and total P. Solids content increased from about 1.5 percent to more than 90 percent. These dewatered solids can be transported more economically off the farm for use as a valuable fertilizer material.

Last Modified: 11/28/2014
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