Phosphate recovery by struvite production from synthetic wastewater using a highly scalable 3D printed filter-press electrochemical flowcell

This study demonstrates the continuous production of value-added struvite (MgNH₄PO₄) from synthetic wastewater at pre-pilot scale using a 3D printed filter-press electrochemical flowcell. The system was operated in full-recirculation mode for 3 hr at a flowrate of 0.62 L/min to create turbulent conditions in the reactor and across the electrode surfaces. Experiments were conducted at pH 8.5 at a current density of 1.7 mA/cm². An average PO₄³ ⁻ recovery of 85 % was achieved, with a struvite yield of 40 %. Precipitates formed on the anode (24 %), in the bulk solution (14 %), and on the cathode (2 %). Although struvite nucleates preferentially on the anode surface, results suggest that the turbulent flow induced partial detachment of struvite from the anode surface. The successful struvite formation was verified with attenuated reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, energy dispersive spectroscopy (EDS) in a scanning electron microscope (SEM), and X-ray diffraction (XRD). All these techniques showed good agreement with known pure struvite characteristics. The results suggest potential extension to industrial and municipal wastewater systems, with future studies addressing process optimization approaches aimed at mitigating anode passivation and enhancing struvite recovery. Overall, the results point to the flexibility and scalability of electrochemical filter-press flowcells for integration into continuous, green wastewater treatment and resource recovery systems.