Growth rate kinetics for struvite crystallization

Harrison, Michael. L., Johns, Michael. R., White, Edward. T. and Mehta, Chirag. M. (2011). Growth rate kinetics for struvite crystallization. In: Jiří Jaromír Klemeš, Petar S. Varbanov and Hon Loong Lam, Pres'11. 14th Conference Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction. Proceedings. Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (14th, PRES, 2011), Firenze, Italy, (309-314). 8–11 May 2011. doi:10.3303/CET1125052

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Author Harrison, Michael. L.
Johns, Michael. R.
White, Edward. T.
Mehta, Chirag. M.
Title of paper Growth rate kinetics for struvite crystallization
Conference name Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (14th, PRES, 2011)
Conference location Firenze, Italy
Conference dates 8–11 May 2011
Proceedings title Pres'11. 14th Conference Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction. Proceedings
Journal name Chemical Engineering Transactions
Place of Publication Milan, Italy
Publisher The Italian Association of Chemical Engineering (AIDIC Servizi)
Publication Year 2011
Sub-type Fully published paper
DOI 10.3303/CET1125052
ISBN 9788895608167
889560816X
ISSN 1974-9791
Editor Jiří Jaromír Klemeš
Petar S. Varbanov
Hon Loong Lam
Volume 25
Start page 309
End page 314
Total pages 6
Collection year 2012
Language eng
Formatted Abstract/Summary
The crystallisation of struvite is one means of removing phosphate (and nitrogen) from nutrient-rich wastewater. As with all crystallisation processes, the growth rate of the crystals and its dependence on supersaturation is of considerable interest in designing processing equipment. Modelling of struvite solubility using the computer package MINTEQA2 showed that struvite exhibits a minimum solubility in moderately alkaline conditions, with increasing solubility in acidic and strongly alkaline solutions, while temperature has only a minimal effect on struvite solubility. To measure the growth rate of struvite crystals, laboratory measurements were conducted in an isothermal batch 1 L stirred seeded crystallizer. Experiments were performed in aqueous solution at three pH levels (7.5, 8.0 and 8.5) and three temperatures (25, 35 and 40°C) for similar initial ionic concentrations with phosphate being the limiting ion. These conditions were chosen to cover the pH values at which struvite readily crystallises without excessive adjustment of the wastewater pH, and at temperatures typical of many wastewaters. The increase in crystal size with time together with the decrease in the concentration of the ionic species in solution were followed. Rapid crystallisation kinetics were observed in the solution, with growth rates over 20 μm/min at pH 8.5. A second order dependence of growth rate on supersaturation (as phosphate concentration) was observed, and the growth rate constant increased as pH increased but was insensitive to temperature over the range of conditions used. Results from a 200 L pilot-scale trial of struvite crystallisation at a local abattoir were consistent with the laboratory results.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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Created: Wed, 13 Jul 2011, 11:28:11 EST by Mr Chirag Mehta on behalf of Advanced Water Management Centre