Submitted to: Recycling of Agricultural Municipal and Industrial Residues
Publication Type: Proceedings
Publication Acceptance Date: 7/6/2006
Publication Date: 8/15/2006
Citation: Szogi, A.A., Vanotti, M.B., Bauer, P.J., Scheckel, K.G., Hudnall, W.H. 2006. Innovative technology for recycling of manure phosphorus with rapid amorphous phosphate precipitation. In: Petersen, S.O., editor. Proceedings of 12th Recycling of Agricultural Municipal and Industrial Residues (RAMIRAN), September 9-12, 2006, Aarhus, Denmark. p. 103-105.
Technical Abstract: Phosphorus (P) recovery from liquid swine manure is an attractive technology when soils on the farm are saturated with P and on-farm land application is not an option. A technology was developed for recovery of soluble P from liquid swine manure as amorphous calcium phosphate (ACP). Soluble P is recovered as a P precipitate by increasing the pH of wastewater adding controlled amounts of hydrated lime after manure solids removal and biological N treatment. The P precipitate is further dewatered using a combination of polymer treatment (anionic polyacrylamide) and polypropylene filter bags. A study was conducted to determine the chemical, mineralogical composition, and potential use as a phosphate fertilizer of precipitates obtained from one pilot and one full-scale treatment plants designed to replace the anaerobic lagoon treatment that is typical in the USA. Samples of the precipitate were subjected to chemical, x-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. Chemical analysis indicated that the precipitate contained >20% P2O5, mostly as plant available P; XRD revealed the predominance of an amorphous mineral phase (ACP); while SEM confirmed the predominance of the amorphous structure of the precipitate. A soil fertility test showed that the recovered phosphate was an excellent source of P for crops with ryegrass yields similar to commercial triple superphosphate. This technology is useful for solving distribution problems of excess manure P in soils and allowing significant amounts of this nutrient to be transported off the farm in concentrated form and recycled as plant fertilizer.