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.
Gongting Wang,Wenqing Luo,Zedong Teng,Xin Zhao,Yuxin Cheng,Yanzhong Wang,Bin Liu,Mengnan Lu,Min Li
Cadmium (Cd) pollution in sediments has become an urgent environmental problem. Humus mediated dissimilatory iron reduction and phosphorus solubilizing bacteria (PSB) were widely used for Cd immobilization. Here, we utilized humic acid (HA) and fulvic acid (FA) to promote the efficiency of iron reduction by Geobacter metallireducens GS-15 to immobilize Cd with the involvement of PSB. The results showed that both HA and FA can facilitate the reduction of Fe(III) and the release of P in ferric phosphate minerals, and then the immobilization of Cd. The immobilization of dissolved Cd 2 + in HA, FA and BCK groups were 76.25 %, 65.25 % and 63.58 %, respectively. HA and FA promoted the growth of PSB and the secretion of acetic acid, high concentration of acetic acid provided sufficient nutrients for the growth of iron-reducing bacteria. Thereby, high concentration of Fe(II) facilitated the recrystallization, which effectively immobilized Cd 2+ . Compared to the CK group, the HA and the FA groups increased the proportion of exchanged Cd converted to combined Cd in secondary minerals by 25.32 % and 19.16 %, respectively. The findings reveal that enhanced effect of HA on microbial iron reduction coupled with PSB can facilitate the immobilization of Cd, providing a promising strategy for the remediation of Cd-contaminated sediments.
危险品化学品经营许可证（带存储）