Wroclaw University of Technology, Faculty of Chemistry, Wroclaw, Poland.
Water Res. 2013 Jul 1;47(11):3635-43. doi: 10.1016/j.watres.2013.04.026. Epub 2013 Apr 24.
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.
连续 DT MSMPR（Draft Tube Mixed Suspension Mixed Product Removal）结晶器中提供了典型的磷矿肥料工业废水（pH < 4，0.445 质量%的 PO4(3-)，存在无机杂质），溶解的基质（氯化镁和氯化铵）和溶液碱化了 MgNH4PO4·6H2O 反应结晶过程的环境。研究在恒定温度 298 K 下进行，假设基质的化学计量比或镁离子的 20%过量。研究了 pH（8.5-10）和平均停留时间（900-3600 s）对产品粒度分布、化学组成、晶体形状、大小均匀性和过程动力学的影响。生成了平均粒径约为 25-37 μm、均匀性 CV 为 70-83%的晶体。使用 20%过量的镁离子、pH 9 和平均停留时间 3600 s 可以生成具有可接受均匀性的最大晶体。在这些条件下，根据 SIG（Size Independent Growth）MSMPR 动力学模型，成核速率不超过 9 × 10(7) 1/(s m(3))。线性晶体生长速率为 4.27 × 10(-9) m/s。镁离子的过量有利于水合碳酸镁反应结晶过程的收率。五价磷酸盐（PO4(V)）离子的浓度从 0.445 降至 9.2 × 10(-4)质量%。这可以被认为是一个非常好的工艺结果。在产物晶体中，除了主要成分水合碳酸镁外，还分析检测到了废水中的所有杂质。
