Multicomponent anion exchange simulation of phosphate removal and recovery from municipal wastewater using Aspen Adsorption

Phosphorus (P) is a finite resource. The depletion of P resources is expected to be reached within a few hundred years. P recovery from municipal wastewater is essential for mitigating eutrophication and ensuring sustainable resource use. Adsorption and ion exchange (IEX) represent promising alternatives to conventional removal methods, offering selective recovery and compliance with increasingly stringent discharge limits. This study presents the first application of Aspen Adsorption to simulate multicomponent continuous-flow P removal and recovery from actual wastewater. The tested sorbent is pyroaurite, a Fe-rich hydrotalcite with high phosphate selectivity. Experimental breakthrough and regeneration tests were reproduced through an Aspen-based multi-component ion exchange model incorporating competition from chloride, sulphate, and bicarbonate. A hybrid parameter estimation procedure enabled robust calibration of equilibrium constants and mass transfer coefficients, overcoming convergence challenges. The validated model successfully predicted (i) the scale-up from 20 to 60 cm packed beds, (ii) repeated adsorption/desorption cycles through the Cycle Organizer, and (iii) the impact of salinity increases relevant to coastal wastewater scenarios. Results showed high correlation between simulations and experimental data (R2 >= 0.90) and demonstrated that pyroaurite maintained effective P removal under saline conditions, with only moderate efficiency losses. These findings highlight Aspen Adsorption as a powerful tool for the design, optimization, and scale-up of phosphate recovery processes, contributing to bridge the gap between lab-scale testing and full-scale application.