The Adsorption/Degradation Of BDE-47 By Pseudomonas Stutters Combined With Nano-fe

In this study, the contribution of Pseudomonas stutzier KS0013(Ps) among biosorption, biodegradation in the removal of 2, 2’, 4, 4’-Tetrabromodiphenylether(BDE-47) and the influence of additional glucose on the biodegradation efficiencies was investigated. The optimizing strategy of influencing factors of biosorption was determined using response surface method(RSM). Isotherm and adsorption kinetic experiments for BDE-47 were performed using batch sorption experiment. The portion of adsorption and degradation amount with additional rhamnolipids were measured to elucidate the mechanism of biosorption. Besides, the influence of Nano-Fe in the removal of BDE-47 by Ps was investigated.Numerous chemical groups such as hydroxyl, carbonyl and carboxyl, thiol, amide, phosphonic acid ester and phosphorus ester have played an important role in the adsorption of BDE-47. And, the intensity at the position of 284.2 C-C and C-H decreased significantly, illustrated that the C-C and C-H groups played a key role in the BDE-47 adsorption. Moreover, the sorption capacity of live Ps was significantly larger than that of heat-killed Ps indicating biosorption of BDE-47 by live Ps was metabolically mediated. The primary mechanism of sorption for dead Ps is partitioning into cell, while the bioaccumulation of BDE-47 plays an important role in biosorption for live Ps.Response surface analysis showed that the initial BDE-47 concentration was the most important factor for adsorption amount by Ps, followed by ionic strength and temperature. For the ballence time, temperature was more important than ionic strength. Taken the two response into consideration, the optimum adsorption conditions are as follows: 33.4°C, ionic strength of 3.03‰, the initial BDE-47 concentration of 0.11 mg·L-1.The growing of Ps and the degradation of BDE-47 without additional carbon sources showed that Ps was able to use BDE-47 as a sole carbon source. However, its biodegradation efficiency was slow with only 29.08±0.96% BDE-47 degradated. During 12-day incubation, biodegradation efficiency of BDE-47 increased from 29.08±0.96% to 65.64±2.43%,73.06 ± 3.12% with addition of 0.2g·L-1 and 0.5 g·L-1 glucose, respectively. In the remove process, BDE-47 was rapidly adsorbed by Ps at the initial stage, and degradation was observed only after 4 hours. Based on the Kp values, the distribution of BDE-47 in water/Ps remained stable.Though the cell surface hydrophobicity of Ps was significantly enhanced with additional rhamnolipid, the addition of rhamnolipids caused an undesired competition in the adsorption of BDE-47. Meanwhile, rhamnolipids was being sorbed to BDE-47 binding sites and subsequently blocking BDE-47 biosorption, therefore posed an adverse effect on biodegradation.The degradation efficiency of BDE-47 with 0.5 and 1.0 g·L-1 Nano-Fe achieved 14 and 22% after 4hrs. Besides, The degradation of BDE-47 by Ps was enhanced with additional Nano-Fe.