Continuous Reaction Crystallization of Struvite in a DTM Type Crystallizer With Jet Pump of Ascending Suspension Flow in a Mixing Chamber–Kinetic Approach of the Process

Agata Mazienczuk, Andrzej Matynia, Krzysztof Piotrowski, Boguslawa Wierzbowska

Silesian University of Technology, Department of Chemical & Process Engineering, Gliwice, Poland.
Wroclaw University of Technology, Faculty of Chemistry, Wroclaw, Poland.

DOI: 10.4236/jcpt.2012.23012                

Abstract

Reaction crystallization of struvite in water solutions containing 0.20 mass % of phosphate(V) ions by magnesium and ammonium ions addition was investigated experimentally. Process was carried out in DTM type crystallizer with liquid jet pump device in 298 K assuming stoichiometric conditions. Struvite crystals of mean size L_m 5.2-23.0 μm were produced depending on pH (9-11) and mean residence time of suspension in a crystallizer τ (900-3600 s). Under these conditions linear growth rate of struvite crystals (SIG MSMPR kinetic model) decreased 2-time with the increase in pH and 3-time with the elongation of mean residence time of crystal suspension from 7.11×10^-9 m/s (pH 9, τ900 s) to 1.65×10^-9 m/s (pH 11, τ3600 s). Nucleation rate varied within the 7.9×10⁸-1.8×10¹⁰ 1/(sm³) limits. Struvite product of maximal linear size exceeded 100 μm with 10 vol. % of < 3 μm fraction corresponded to pH 9 and τ3600 s.

Keywords

Struvite; Crystal Size Distribution (CSD); Reaction Crystallization Kinetics; Continuous DTM Type Crystallizer; Jet Pump

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	S. A. Parsons, “Recent Scientific and Technical Developments: Struvite Precipitation,” CEEP Scope Newslett., No. 41, 2001, pp. 15-22.
[2]	J. Doyle and S. A. Parsons, “Struvite Formation, Control and Recovery,” Wat. Res., Vol. 36, 2002, pp. 3925-3940. doi:10.1016/S0043-1354(02)00126-4.
[3]	K. S. Le Corre, E. Valsami-Jones, P. Hobbs and S. A. Parsons, “Phosphorus Recovery From Wastewater by Struvite Crystallization: A Review,” Crit. Rev. Environ. Sci. Technol., Vol. 39, No. 6, 2009, pp. 433-477. doi:10.1080/10643380701640573.
[4]	A. Matynia, J. Koralewska, K. Piotrowski and B. Wierzbowska, “The Influence of the Process Parameters on the Struvite Continuous Crystallization Kinetics,” Chem. Eng. Comm., Vol. 193, No. 2, 2006, pp. 160-176. doi:10.1080/009864490949008.
[5]	J. Koralewska, K. Piotrowski, B. Wierzbowska and A. Matynia, “Kinetics of Reaction-Crystallization of Struvite in the Continuous Draft Tube Magma Type Crystallizers-Influence of Different Internal Hydrodynamics,” Chinese J. Chem. Eng., Vol. 17, No. 2, 2009, pp. 330-339. doi:10.1016/S1004-9541(08)60212-8.
[6]	A. Matynia, A. Mazienczuk, B. Wierzbowska, A. Kozik and K. Piotrowski, “New Crystallizers With a Compressed Air-driven Jet Pump in the Process of Precipitating Struvite From Diluted Water Solutions Containing Phosphate Ions,” Chemik, Vol. 64, No. 11, 2010, pp. 753-758 (in Polish).
[7]	L. E. de-Bashan and Y. Bashan, “Recent Advances in Removing Phosphorus From Wastewater and Its Future Use as Fertilizer,” Wat. Res., Vol. 38, 2004, pp. 4222-4246. doi:10.1016/j.waters.2004.07.014.
[8]	J. W. Mullin, “Crystallization,” Butterworth-Heinemann., Oxford, 1993.
[9]	Z. Rojkowski and J. Synowiec, “Crystallization and the Crystallizers,” 1st Edition, WNT, Warszawa, 1991 (in Polish).
[10]	P. Synowiec, “Industrial Crystallization From Solution,” 1st Edition, WNT, Warszawa, 2008 (in Polish).
[11]	A. Matynia, “Crystallizers With a Jet Pump,” Inz. Ap. Chem. Vol. 36, No. 6, 1997, pp. 9-14 (in Polish).
[12]	A. D. Randolph and M. A. Larson, “Theory of Particulate Processes: Analysis and Techniques of Continuous Crystallization,” 2nd Edition, Academic Press, New York, 1988.
[13]	J. Koralewska, K. Piotrowski, B. Wierzbowska and A. Matynia, “Reaction-Crystallization of Struvite in a Continuous Liquid Jet Pump DTM MSMPR Crystallizer With Upward Circulation of Suspension in a Mixing Chamber – an SDG Kinetic Approach,” Chem. Eng. Technol., Vol. 30, No. 11, 2007, pp. 1576-1583. doi:10,1002/ceat.200700229.
[14]	J. Koralewska, N. Hutnik, K. Piotrowski, B. Wierzbowska and A. Matynia, “Effect of Reaction Crystallization Parameters on the Quality of Struvite Crystals Produced in a Continuous Draft Tube Magma Crystallizer With a Jet Pump Fed With Recirculated Mother Solution,” Przem. Chem., Vol. 88, No. 5, 2009, pp. 472-476 (in Polish).
[15]	J. Koralewska, N. Hutnik, B. Wierzbowska, K. Piotrowski and A. Matynia, “Separation of Crystalline Struvite From Diluted Solutions in a DTM Crystallizer With Liquid Jet Pump of Descending Suspension Flow in a Mixing Chamber,” Przem. Chem., Vol. 89, No. 8, 2010, pp. 1087-1091 (in Polish).