Multivariate optimization of phosphate removal and recovery from aqueous solution by struvite crystallization in a fluidized-bed reactor

Abstract

AbstractStruvite crystallization has been widely studied for phosphate removal and recovery from aqueous systems. In this study, struvite crystallization was carried out in a fluidized-bed reactor. Multivariate optimization was conducted using Box–Behnken design (BBD) with influent pH, influent phosphate concentration, and Mg/P molar ratio as independent variables. The output variables comprised total and dissolved phosphate concentrations, ammonium and magnesium concentrations, and fines concentrations. Experimental values of the total phosphate and dissolved phosphate concentrations ranged from 25.6 to 109.4 mg/L and from 7.6 to 39.3 mg/L, respectively, while the fines concentration varied from 5.2 to 101.6 mg/L. Quadratic mathematical models describing the response behavior of experimental BBD data were generated for total phosphate, dissolved phosphate, and fines concentration. The model p-values ( 0.05) were insignificant. Numerical optimiza...