Application of a continuous FB MSZ type crystallizer with jet pump driven by compressed air for recovery of phosphate(V) ions from mineral fertilizer industry wastewater

Year 2013, Volume: 3 Issue: 4, 26 - 34, 23.07.2016

Agata Mazienczuk Nina Hutnik Krzysztof Piotrowski Anna Kozik Andrzej Matynia

Abstract

New original construction of continuous FB MSZ (Fluidized Bed with Mixed Suspension Zone) crystallizer with internal circulation of suspension driven by jet pump fed with compressed air was used for continuous reaction crystallization of struvite MgNH4PO4∙6H2O from phosphorus fertilizers industry wastewater by magnesium and ammonium ions addition. This wastewater of pH < 4 contained 0.445 mass % of phosphate(V) ions and impurities: aluminium, calcium, copper, iron, potassium, magnesium, titanium, zinc, fluosilicate, fluoride and sulphate(VI) ions. Tests were carried out in 298 K, in stoichiometric conditions and at 20% excess of magnesium ions. Crystals of mean size. 27 – 43 µm were produced. Struvite crystals of the largest sizes and acceptable homogeneity were produced at 20% excess of magnesium ions, at pH 9 and elongated mean residence time of suspension 3600 s. Corresponding crystal linear growth rate was 8.52⋅10–9 m/s according to SIG MSMPR (Size Independent Growth, Mixed Suspension Mixed Product Removal) kinetic model. Concentration of phosphate(V) ions decreased from 0.445 mass % in a feed to 9.3∙10–4 mass % in a postprocessed mother solution. In a product, besides main crystalline component – struvite, also all impurities from wastewater appeared in a form of hydroxides, phosphates(V) and other salts

Keywords

Struvite, FB MSZ crystallizer, industrial wastewater, continuous reaction crystallization, product quality, kinetics, phosphorus recycling

References

• de–Bashan, L.E. & Bashan, Y. (2004). Recent advances in removing phosphorus from wastewater and its future use as fertilizer. Wat. Res. 38, 4222–4246.
• Corre, K.S. Le, Valsami–Jones, E., Hobbs, P. & Parsons, S.A. (2009). Phosphorus recovery from wastewater by struvite crystallization: A review. Crit. Rev. Environ. Sci. Technol. 39, 433–477.
• Doyle, J. & Parsons, S.A. (2002). Struvite formation, control and recovery. Wat. Res. 36, 3925–3940.
• Hutnik, N., Piotrowski, K., Gluzinska, J. & Matynia, A. (2011). Effect of selected inorganic impurities present in real phosphate(V) solutions on the quality of struvite crystals produced in continuous reaction crystallization process. Progr. Environ. Sci. Technol. 3, 559–566.
• Hutnik, N., Wierzbowska, B. & Matynia, A. (2012). Effect of inorganic impurities on quality of struvite in continuous reaction crystallization at the excess of magnesium ions. Przem. Chem. 91, 762–766 (in Polish).
• Kozik, A., Matynia, A. & Piotrowski, K. (2012). Recovery o struvite from diluted aqueous solutions of phosphate(V) ions in the presence of magnesium ions excess. In: J. Markoš (Ed.): Proceedings of the 39th International Conference of Slovak Society of Chemical Engineering, Tatranskě Matliare, Slovakia, 742–749.
• Matynia, A. (1997). Crystallizers with a jet pump. Inż. Ap. Chem. 36(6), 9–14 (in Polish).
• Matynia, A., Piotrowski, K., Ciesielski, T. & Liszka, R. (2009). New constructions of crystallizer with a compressed air driven jet–pump in the phosphorus recycling technology. Przem. Chem. 88, 505–508 (in Polish).
• Mullin, J.W. (1993). Crystallization. Oxford: Butterworth–Heinemann. Parsons, S.A. (2001). Recent scientific and technical developments: Struvite precipitation. CEEP Scope Newslett. 41, 15–22. Randolph, A.D. & Larson, M.A. (1988). Theory of particulate processes: Analysis and techniques of continuous crystallization. New York: Academia Press. Synowiec, P. (2008). Industrial crystallization from solution. Warszawa: WNT (in Polish).