title: Removal of phosphorus from livestock effluents.
abstract: For removal of phosphorus (P) from swine liquid manure before land application, we developed a treatment process that produces low P effluents and a valuable P by-product with minimal chemical addition and ammonia losses. The new wastewater process included two sequential steps: (i) biological nitrification and (ii) increasing the pH of the nitrified wastewater to precipitate P. We hypothesized that by reduction of inorganic buffers (NH(4)(+) and carbonate alkalinity) via nitrification, P could be selectively removed by subsequent hydrated lime [Ca(OH)(2)] addition. The objective of the study was to assess if this new treatment could consistently reduce inorganic buffer capacity with varied initial concentrations of N (100-723 mg NH(4)(+) L(-1)), P (26-85 mg TP L(-1)), and alkalinity (953-3063 mg CaCO(3) L(-1)), and then efficiently remove P from swine lagoon liquid. The process was tested with surface lagoon liquids from 10 typical swine farms in North Carolina. Each lagoon liquid received treatment in a nitrification bioreactor, followed by chemical treatment with Ca(OH)(2) at Ca rates of 0, 2, 4, 6, 8, 10, and 12 mmol L(-1) to precipitate P. This configuration was compared with a control that received the same Ca rates but without the nitrification pretreatment. The new process significantly reduced >90% the inorganic buffers concentrations compared with the control and prevented ammonia losses. Subsequent lime addition resulted in efficient pH increase to > or = 9.5 for optimum P precipitation in the nitrified liquid and significant reduction of effluent total P concentration versus the control. With this new process, the total P concentration in treated liquid effluent can be adjusted for on-farm use with up to >90% of P removal. The recovered solid Ca phosphate material can be easily exported from the farm and reused as P fertilizer. Therefore, the new process can be used to reduce the P content in livestock effluents to levels that would diminish problems of excess P accumulation in waste-amended soils.
authors.affiliation: USDA-ARS Coastal Plains Soil, Water and Plant Research Center, 2611 W. Lucas St., Florence, SC 29501-1242, USA. Ariel.Szogi@ARS.USDA.GOV
authors.forename: Ariel A
authors.initials: AA
authors.lastname: Szogi
authors.forename: Matias B
authors.initials: MB
authors.lastname: Vanotti
mesh_terms: D000818:Animals; D019149:Bioreactors; D017610:Calcium Compounds / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry; D011232:Chemical Precipitation; D006863:Hydrogen-Ion Concentration; D010087:Oxides / Q000737:chemistry; D010758:Phosphorus / Q000302:isolation & purification*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D013552:Swine; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D017610:Calcium Compounds; D002254:Carbonates; D010087:Oxides; D000644:Quaternary Ammonium Compounds; D010758:Phosphorus; C016538:lime