Sediment remediation by La-MOF/PP fabric coupled with phosphate solubilizing bacteria: Phosphate activation and removal

Endogenous phosphorus (P) release is one of the key factors leading to eutrophication of water body. Phosphorus in sediments is difficult to be removed or recovered due to its chemical stability and complex morphology. Meanwhile, lanthanide metal organic framework (La-MOF) shows high efficiency in phosphate adsorption, but faces challenges in solid-liquid separation due to its powder form. In this study, the phosphorus solubilizing bacteria (PSB), Leclercia adecarboxylata L1–5, was used to transform some fractions of insoluble phosphorus in sediment into soluble phosphorus, and the La-MOF/Polypropylene (La-MOF/PP) fabric was innovatively prepared for phosphate adsorption. Solvothermal method was used for the preparation of La-MOF/PP fabric and the optimum synthesis time was 12 h. The best effect of phosphate removal was achieved when the La-MOF/PP fabric dosage was 1 g/L and the pH was 7. The regeneration efficiency of the material remained stable after five cycles of adsorption and desorption. Furthermore, the simulation results showed that PSB can release dissolved phosphate up to 5.40 mg P/L from sediment. After coupling with the La-MOF/PP fabric, the concentration of phosphate in the overlying water was significantly reduced to 0.38 mg P/L, which was much lower than that in the CK group (2.4 mg P/L). This study demonstrated that the coupled system of PSB and La-MOF/PP fabric could effectively reduce the sediment phosphate content, mitigate the negative impact of possible release of sediment phosphorus and degradation of the overlying water quality. It provided a promising technique for in-situ remediation of sediment phosphate.