Study on the removal of fluoride from water by modified phosphogypsum and microbial mineralization

Abstract BACKGROUND Fluoride contamination in water and the large‐scale accumulation of phosphogypsum represent two persistent environmental challenges. Conventional fluoride‐removal technologies often rely on specially synthesized adsorbents or soluble calcium salts, while the potential of calcium‐rich phosphogypsum as a functional substrate for biomineralization remains insufficiently explored. This study therefore coupled a fluoride‐tolerant bacterial isolate with modified phosphogypsum (MPG) to simultaneously enhance fluoride removal and promote phosphogypsum valorization. RESULTS Achromobacter sp. strain F‐24 maintained growth over a pH range of 5–9 and showed tolerance to low‐to‐moderate fluoride concentrations. At an initial fluoride concentration of 5 mg L −1 and an MPG dosage of 4 g L −1 , the combined F‐24–MPG system achieved a fluoride removal efficiency of 75–77%, compared with approximately 20–30% for strain F‐24 alone and 22–24% for MPG alone. Fluoride uptake by MPG was better described by the pseudo‐first‐order kinetic model, while the equilibrium data were more consistent with the Freundlich isotherm model. Scanning electron microscopy, X‐ray diffraction, and Fourier transform infrared analyses revealed changes in surface morphology, mineral characteristics, and functional groups after bacterial treatment, indicating biomineralization‐associated precipitation and increased fluoride‐retention sites. CONCLUSION The integration of strain F‐24 with MPG substantially improved fluoride removal relative to either component alone. The main innovation of this work lies in using MPG not only as a calcium‐containing substrate for bacterial biomineralization but also as a waste‐derived functional material for fluoride treatment. This coupled strategy provides a proof‐of‐concept route for linking water defluoridation with phosphogypsum resource utilization, although fluoride‐release stability and strain‐specific biosafety require further evaluation before practical application. © 2026 Society of Chemical Industry (SCI).