Modelling Phosphorus Recovery from Urban Wastewater

Calcium phosphate and struvite crystallization has been widely studied for phosphate removal and recovery from urban wastewater. In this study, calcium phosphate and struvite crystallization were carried out in a fluidized-bed reactor. Experimental values of the P concentration ranged from 117-1000 mg P/l in feed water and 37-457 mg P/l in the bottom of the reactor. Black-box approach to model the two processes was conducted using multiple linear regression. Pearson correlation analysis describes the correlations of experimental data generated for all parameters. With regard of inflow, chemicals dosing, pH, related ion concentrations, and molar ratio (Ca/P and NH4/P) were selected as independent variables. They are found to be significant through Pearson’s correlation analysis and knowledge of crystallization process. The output variable comprises P crystallization fraction. Consequently, the information used to generate model equations. Both models, calcium phosphate and struvite acquired R2 higher than 0.7 and low Std. Error (<10) allowing good prediction models. Experimental data and generated predicted values are close to each other. In addition, if applied in a realistic setting, the models show over-estimated values, which need to be considered in the economic analysis.