Synchronous algae and phosphorus removal by Ceramsite@Fe2O3 (FC) via taking the algae as crystal nuclei of hydroxylapatite

Abstract Excessive phosphorus in the freshwater commonly cause eutrophication and even harmful algal blooms (HABs). In this study, the modified ceramsite loaded Fe2O3 nano-particles (Ceramsite@Fe2O3 referred to as FC) was synthesized successfully to remove algae and phosphorus synchronously accompanying the slow and sustained release of Ca2+. It exhibits superior synergistic removal performance with 100% removal of algae (3.2 × 106 cells/mL) and phosphorus (5 mg/L) within 60 h, respectively. Hererin, the loaded Fe2O3 can continuously adsorb phosphorus to restrain the re-growth of algae (The concentration of algae is 0 cells/mL after 30 days of re-increasing the phosphorus). Meanwhile, negatively charged algae would adsorb positively charged Ca2+ released from FC, and then combined with phosphate to from hydroxylapatite (Ca10(PO4)6(OH)2). Finally, the synchronous removal of algae and phosphorus was achieved by the hydroxylapatite through the co-precipitation. In brief, this work provide a simple-efficient method for the treatment of eutrophic water.