Effect of aluminum ions on struvite reaction crystallization from wastewaters from phosphorus fertilizer industry

摘要

Struvite was crystallized from aq. solns. contg. PO43- 1.0, 0.445 or 0.20% by mass and AI(3+) 6.4, 20 or 100 mg/kg after addn. of Mg and NH4 ions. The reaction crystn. of struvite ran under stoichiometric conditions and at 20% excess of Mg ions in a crystallizer with internal circulation at 298 K, pH 9 or 11, for suspension residence time of tau 900 or 3600 s. The struvite crystals (size 16.7-56.7 mu m) were pptd. The presence of Al ions resulted in improving the product quality (struvite crystals size increased by ca. 8 mu m in av.). Presence of struvite crystals with MOH), particles (up to 1.9% by mass) was evidented. The results were compared with quality of the products recovered from real wastewater from PO43- fertilizer industry.