Batch fluidized bed reactor based modified biosynthetic crystals: Optimization of adsorptive properties and application in fluoride removal from groundwater

A batch fluidized bed reactor (BFBR) with modified biosynthetic crystals (MBC), derived from Pseudomonas sp. HXF1, was investigated for the treatment of the groundwater containing fluoride (F−). Impacts of different hydraulic retention time (HRT), pH, and initial F− concentration on F− removal were examined and the maximum defluorination efficiency was recorded as 95.20%. Moreover, recycling experiments were performed to evaluate the stability of repeated use. BFBR/MBC system showed a long-term effective treatment outcome with low fluctuation in the concentrations of residual Ca2+ and F−. The formed precipitates were characterized by SEM, XPS, XRD, and FTIR. The defluorination mechanisms of BFBR/MBC system were defined as the chemisorption and induced crystallization of Ca5(PO4)3F on the MBC surface. As a feasible, economical, and environment-friendly technique, the method has a long-term value, which suggests promising applications in F− removal and resourceful treatment. [Display omitted] •A batch fluidized bed reactor was developed with modified biosynthetic crystals.•Under the optimum conditions, fluoride (F−) removal reached to 95.20%.•Residual Ca2+ and F− remained below 120 and 0.4 mg L−1 after 42 cycles.•F− removal occurred simultaneously by both coprecipitation and adsorption.