Abstract
<jats:p>To address the dual environmental challenges of phosphorus resource scarcity and aquatic eutrophication, and to resolve acid mine drainage (AMD) pollution, this study proposes a synergistic resource recovery strategy based on the principle of "waste treatment with waste". It utilizes the abundant Fe(II) in AMD to recover the high - value ferrous phosphate mineral, vivianite (Fe3(PO4)2·8H2O) from phosphorus - containing wastewater. Comprehensive static experiments identified the optimal vivianite crystallization parameters: pH = 7 and Fe/P molar ratio = 2:1. Under these conditions, the Fe2+ removal rate reached 86.25%. The synthesized vivianite exhibited a well-defined structure with an Fe/P atomic ratio of 1.54, close to the theoretical value, and the highest purity. The interference mechanism of coexisting ions was revealed: Mg2+ competes with PO43− and NH4+ to form struvite (MgNH4PO4·6H2O); under anaerobic conditions, the reduction of SO42− in an anaerobic environment competes with PO43− for Fe (II) to form FeS, which destroys the vivianite structure and releases PO43−. Building upon the results of the static experiments, a fluidized bed crystallization reactor was established for engineering verification. Under the optimized operational conditions (pH = 7, Fe/P molar ratio = 1.5:1, upflow velocity = 2.12 cm/min), the reactor operated stably, and the product was identified as vivianite via physicochemical characterization. This process realized the simultaneous purification of AMD and recovery of phosphorus resources, while the Fe/P molar ratio under dynamic conditions is reduced to the theoretical value (1.5:1), substantially lowering iron source consumption and offering a viable technical approach for the circular economy.</jats:p>