title: Chemical interferences when using high gradient magnetic separation for phosphate removal: consequences for lake restoration.
abstract: A promising method for lake restoration is the treatment of lake inlets through the specific adsorption of phosphate (P) on strongly magnetizable particles (Fe) and their subsequent removal using in-flow high gradient magnetic separation (HGMS) techniques. In this work, we report an extensive investigation on the chemical interferences affecting P removal efficiencies in natural waters from 20 Mediterranean ponds and reservoirs. A set of three treatments were considered based on different Fe particles/P concentration ratios. High P removal efficiencies (>80%) were found in freshwater lakes (conductivities<600 μ S cm(-1)). However, a significant reduction in P removal was observed for extremely high mineralized waters. Correlation analysis showed that major cations (Mg(2+), Na(+) and K(+)) and anions (SO(4)(2-) and Cl(-)) played an essential role in P removal efficiency. Comparison between different treatments have shown that when increasing P and Fe concentrations at the same rate or when increasing Fe concentrations for a fixed P concentration, there exist systematic reductions in the slope of the regression lines relating P removal efficiency and the concentration of different chemical variables. These results evidence a general reduction in the chemical competition between P and other ions for adsorption sites on Fe particles. Additional analyses also revealed a reduction in water color, dissolved organic carbon (DOC) and reactive silicate (Si) concentrations with the addition of Fe microparticles.
authors: Instituto del Agua, Universidad de Granada, 18071 Spain. ivicente@ugr.es
authors: I
authors: I
authors: de Vicente
authors: A
authors: A
authors: Merino-Martos
authors: F
authors: F
authors: Guerrero
authors: V
authors: V
authors: Amores
authors: J
authors: J
authors: de Vicente
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000032:analysis; D002412:Cations; D002621:Chemistry / Q000379:methods*; D005618:Fresh Water; D007477:Ions / Q000032:analysis; D060106:Lakes; D008956:Models, Chemical; D009930:Organic Chemicals; D010710:Phosphates / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis; D061005:Ponds; D012044:Regression Analysis; D017640:Silicates / Q000032:analysis; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods*
chemical_list: D002412:Cations; D007477:Ions; D009930:Organic Chemicals; D010710:Phosphates; D017640:Silicates; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D002244:Carbon