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Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Pp. 612-619 in the Ninth International Animal, Agricultural and Food Processing Wastes Proceedings of the 12-15 October 2003 Symposium (Research Triangle Park, North Carolina USA), Publication Date 12 October 2003.  701P1203.(doi:10.13031/2013.15299)
Authors:   A. A. Szögi, M. B. Vanotti, and P. G. Hunt
Keywords:   Phosphorus removal, animal waste treatment, swine wastewater, N/P ratio, CAFO, manure P, hog lagoons

A major problem in sustainability of animal production is excess of manure phosphorus (P) exceeding land assimilative capacity. Land application of manure results in P buildup in soil and increased potential for P losses through runoff and subsequent eutrophication of surface waters. A wastewater treatment process was developed for removal of P from livestock wastewater. Phosphorus is selectively precipitated using an alkaline earth metal after carbon and ammonia buffers are reduced with a nitrification pretreatment. The method was tested with wastewater collected from nine hog lagoons in North Carolina. In all cases, the soluble P was effectively recovered as P precipitate. When used as a lagoon retrofit, the technology enables precision control of the N:P ratio of the treated effluent to desired levels to match specific crop needs or to solve problems of P accumulation in soil or remediation of contaminated spray fields. The final product is calcium phosphate that can be exported from the farm and reused as fertilizer.

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