The application of process systems engineering to the development of struvite recovery systems

Abstract

A model for struvite suspension crystallisation from seed, incorporating solution thermodynamics and crystal growth kinetics, is developed. The set of differential algebraic equations is implemented within the gPROMS simulation environment. The aqueous phase chemical equilibria employed in the model are validated against PHREEQc. Unknown kinetic model parameters related to crystal growth rates were successfully estimated, by combining this model with an ensemble of data generated in three separate experiments carried out in a 44-l suspension crystalliser. In principle this model can be used for more confident process design of suspension crystallisation of struvite. The approach described can potentially be applied to precipitation-based struvite recovery systems.