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.