title: Phosphates (V) recovery from phosphorus mineral fertilizers industry wastewater by continuous struvite reaction crystallization process.
abstract: Continuous DT MSMPR (Draft Tube Mixed Suspension Mixed Product Removal) crystallizer was provided with typical wastewater from phosphorus mineral fertilizers industry (pH < 4, 0.445 mass % of PO4(3-), inorganic impurities presence), dissolved substrates (magnesium and ammonium chlorides) and solution alkalising the environment of struvite MgNH4PO4·6H2O reaction crystallization process. Research ran in constant temperature 298 K assuming stoichiometric proportions of substrates or 20% excess of magnesium ions. Influence of pH (8.5-10) and mean residence time (900-3600 s) on product size distribution, its chemical composition, crystals shape, size-homogeneity and process kinetics was identified. Crystals of mean size ca. 25-37 μm and homogeneity CV 70-83% were produced. The largest crystals, of acceptable homogeneity, were produced using 20% excess of magnesium ions, pH 9 and mean residence time 3600 s. Under these conditions nucleation rate did not exceed 9 × 10(7) 1/(s m(3)) according to SIG (Size Independent Growth) MSMPR kinetic model. Linear crystal growth rate was 4.27 × 10(-9) m/s. Excess of magnesium ions influenced struvite reaction crystallization process yield advantageously. Concentration of phosphate(V) ions decreased from 0.445 to 9.2 × 10(-4) mass %. This can be regarded as a very good process result. In product crystals, besides main component - struvite, all impurities from wastewater were detected analytically.
authors.affiliation: Wroclaw University of Technology, Faculty of Chemistry, Wroclaw, Poland. nina.hutnik@pwr.wroc.pl
authors.forename: Nina
authors.initials: N
authors.lastname: Hutnik
authors.forename: Anna
authors.initials: A
authors.lastname: Kozik
authors.forename: Agata
authors.initials: A
authors.lastname: Mazienczuk
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Piotrowski
authors.forename: Boguslawa
authors.initials: B
authors.lastname: Wierzbowska
authors.forename: Andrzej
authors.initials: A
authors.lastname: Matynia
mesh_terms: D003460:Crystallization / Q000379:methods*; D005308:Fertilizers; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry; D017616:Magnesium Compounds / Q000737:chemistry / Q000302:isolation & purification*; D010710:Phosphates / Q000737:chemistry / Q000302:isolation & purification*; D000069877:Struvite; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D005308:Fertilizers; D007220:Industrial Waste; D008274:Magnesium; D017616:Magnesium Compounds; D010710:Phosphates; D000069877:Struvite; D062065:Wastewater