Struvite crystallization in fed-batch pilot scale and description of solution chemistry of struvite

Abstract

Struvite (MgNH4PO4·6H2O) encrusts naturally in high turbulence zones of nutrient rich wastewater. Struvite has a potential to be used as slow release boutique fertilizer. This study aims to evaluate struvite precipitation potential using thermodynamic modelling. The thermodynamic model was developed using gPROMS process simulation software, incorporating the solution chemistry of magnesium, ammonium and phosphate. The simulation results describe the detailed speciation of solution used in fed-batch struvite crystallization. The solution speciation of struvite incorporates the concentration of free ions and the relevant complexes together with the solubility status of solution. Finally, this paper includes the investigation of struvite drying temperature using moisture analysing technique, together with the elemental analysis using powder XRD technique and the identification of struvite morphology using electron micrograph.