Mg-Fe bimetallic oxide nanocomposite for superior phosphate removal and recovery from aquatic environment: Synergistic effects of sorption and struvite crystallization

Achieving efficient phosphorus removal and recovery from the aquatic environment is crucial for wastewater engineering, surface water management, and sustainable development. Herein, magnetic and cost-effective Mg-Fe bimetallic oxide nanocomposite was developed via the thermal transformation of Mg-Fe bimetallic hydroxide. The effects of solution pH, dosage concentration, N/P ratio, composition proportion, contact time, and initial phosphorus concentration on the nutrient recovery efficiency were extensively examined by the batch experiments. The magnetic Mg-Fe bimetallic oxide nanocomposite exhibited superior removal for nutrients with the maximum removal capacities of 318.6 mg P/g and 138.2 mg N/g. Quantitative and qualitative analyses demonstrated that the struvite was harvested in high phosphate concentration effluent, and the mechanism involved was synergistic of sorption and struvite crystallization. Notably, due to the coupling sorption effects of Fe3O4 and MgO in nanocomposite, ultralow-level phosphate (below 0.01 mg/L) could be achieved after the treatment of low-level phosphate by the Mg-Fe bimetallic oxide nanocomposite. The results indicated that the designed magnetic Mg-Fe bimetallic oxide nanocomposite could be potentially used for sustainable and efficient phosphate removal and recovery from aquatic environment.