title: Optimization of phosphorus precipitation from swine manure slurries to enhance recovery.
abstract: Laboratory experiments were conducted using magnesium chloride (MgCl2 x 6H2O, 64% solution) to force the precipitation of phosphorus and reduce the concentration of soluble phosphorus (PO4(3-)) in two swine wastes. One of the swine wastes tested contained a high concentration of PO4(3-) (initially approximately 1,000 mg/L), and the other swine waste tested contained a low concentration of PO4(3-) (initially approximately 230 mg/L). The precipitation reactions were performed to determine the required reaction time, pH, magnesium addition rate and seed material for future precipitate recovery work. For the high and low concentration waste, a 10-minute reaction time at a pH of 8.6 was sufficient to remove 98 and 96% of the PO4(3-) from solution. A molar ratio of Mg2+:PO4(3-) of 1.6:1 was determined to be effective for PO4(3-) removal from both the low and high strength wastes. At a molar ratio of 1.6:1, the PO3- in the high concentration waste was reduced from 590 to 12 mg/L. In the low concentration waste, the PO4(3-) concentration was reduced from 157 to 15 mg/L. Seeding the reaction did not significantly enhance the recovery process.
authors.affiliation: The University of Tennessee, Biosystems Engineering and Environmental Science, 2506 E.J. Chapman Drive, Knoxville, Tennessee 37996-4531, USA. rburns@utk.edu
authors.forename: R T
authors.initials: RT
authors.lastname: Burns
authors.forename: L B
authors.initials: LB
authors.lastname: Moody
authors.forename: I
authors.initials: I
authors.lastname: Celen
authors.forename: J R
authors.initials: JR
authors.lastname: Buchanan
mesh_terms: D000818:Animals; D011232:Chemical Precipitation; D003247:Conservation of Natural Resources; D015636:Magnesium Chloride / Q000737:chemistry; D008372:Manure; D010758:Phosphorus / Q000737:chemistry* / Q000302:isolation & purification*; D012995:Solubility; D013552:Swine; D014865:Waste Disposal, Fluid; D014876:Water Pollution / Q000517:prevention & control
chemical_list: D008372:Manure; D015636:Magnesium Chloride; D010758:Phosphorus