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INNOVATIVE TECHNOLOGY FOR RECYCLING OF MANURE PHOSPHORUS WITH RAPID AMORPHOUS PHOSPHATE PRECIPITATION
Citation:
SZOGI, A. A., M. B. VANOTTI, P. J. BAUER, K. G. SCHECKEL, AND W. H. HUDNALL. INNOVATIVE TECHNOLOGY FOR RECYCLING OF MANURE PHOSPHORUS WITH RAPID AMORPHOUS PHOSPHATE PRECIPITATION. Presented at 12th RAMIRAN (Network on Recycling of Agricultural, Municipal and Industrial Residues in Agriculture) International Conference, Copenhagen, DENMARK, September 11 - 13, 2006.
Impact/Purpose:
to present information
Description:
Phosphorus (P) recovery from liquid swine manure is an attractive technology when soils in 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). This technology is highly desirable because the precipitation process is rapid, and compared to crystallizers, it does not require adding a substrate such as sand grains or mineral seeding inside the reaction chamber to promote phosphate precipitation. Soluble P is recovered after manure solids removal and biological N treatment by increasing the pH of wastewater by adding controlled amounts of hydrated lime [Ca(OH)2] to rapidly form a P prcipitate. 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 a field pilot treatment plant designed for swine manure 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 in land areas where it is needed.