title: Using a chemical equilibrium model to predict amendments required to precipitate phosphorus as struvite in liquid swine manure.
abstract: Precipitation of phosphate minerals from liquid swine manure is an established means of reducing the orthophosphate (OP) concentration. This project investigated the usefulness of a chemical equilibrium model, Visual Minteq, for prescribing the amendments needed to maximize struvite precipitation from liquid swine manure and thus reduce the OP phosphorus concentration. The actual concentrations of Mg(2+), Ca(2+), K(+), OP, NH(4)(+), alkalinity and pH from a liquid swine manure system were used as inputs to the model. The model was modified to remove species with extremely low formation rates, because they would not significantly precipitate in the reaction occurring in a short retention-time process such as those envisioned for swine manure struvite-formation reactors. Using the model's output, a series of 19-L reactors were used to verify the results. Verification results demonstrated that Visual Minteq can be used to pre-determine the concentration of amendments required to maximize struvite recovery.
authors.affiliation: Biosystems Engineering and Soil Science, The University of Tennessee, Knoxville, 2506 E. J. Chapman Drive, Knoxville, TN 37996 4531, USA.
authors.forename: Ipek
authors.initials: I
authors.lastname: Celen
authors.forename: John R
authors.initials: JR
authors.lastname: Buchanan
authors.forename: Robert T
authors.initials: RT
authors.lastname: Burns
authors.forename: R Bruce
authors.initials: RB
authors.lastname: Robinson
authors.forename: D Raj
authors.initials: DR
authors.lastname: Raman
mesh_terms: D000641:Ammonia / Q000737:chemistry; D000822:Animal Husbandry; D000818:Animals; D002118:Calcium / Q000737:chemistry; D011232:Chemical Precipitation; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D008274:Magnesium / Q000737:chemistry*; D017616:Magnesium Compounds / Q000737:chemistry*; D008372:Manure; D008956:Models, Chemical; D010710:Phosphates / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry; D015203:Reproducibility of Results; D000069877:Struvite; D013552:Swine; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D007220:Industrial Waste; D017616:Magnesium Compounds; D008372:Manure; D010710:Phosphates; D000641:Ammonia; D000069877:Struvite; D008274:Magnesium; D011188:Potassium; D002118:Calcium