Usage of phosphoric acid plant's circulate pond waters in struvite precipitation—Effect of conditions

Struvite is a suitable fertilizer, and electrochemical precipitation of nutrients from industrial waters provides one answer to the circular economy. Molar ratio between ammonium and phosphate is crucial: Water suitable for the precipitation includes more or at least the same amount ammonium than phosphate. That kind of water typically does not exist in industry. Therefore, ammonium‐rich industrial water was mixed with phosphorus‐rich water to obtain a suitable molar ratio for struvite precipitation. Parameters were studied to determine their effect on removal‐% and struvite yield. 100% struvite yield was obtained under several conditions even without pH control with pH 7–9. The highest phosphate removal (99.7%) was occurred with the molar ratio 1.7:2:1 for Mg:NH4:PO4 (pH 9.0). Waters dilution prevents magnesium anode corrosion. Formed struvite has potential as recycled fertilizer due to low bioavailability of metals and high leachability of nutrients studied by four‐stage sequential leaching. Electrochemical precipitation was used to prepare struvite from phosphoric acid plant's circulate pond waters. Over 99% phosphate removal was achieved, and purity of struvite was analysed by XRD.