铜抗性菌株的筛选及其对Cu2+的吸附性能

利用选择性培养基分离出铜抗性细菌BX,经鉴定该菌为产碱普罗威登斯菌(Providencia alcalifaciens)。考察了细菌BX对环境的适应性,讨论了pH、初始Cu²⁺浓度等对其吸附铜离子的影响,分析了吸附过程的动力学及等温吸附特性,并以多孔陶瓷为载体对其进行固定化。结果表明,该菌对Cu²⁺和NaCl的抗性浓度分别为7 mmol·L^-1和7.5%,可生长于pH4.0～11.0、15～50℃的环境中;其最佳吸附条件为pH5.5、温度30℃、起始Cu²⁺浓度100 mg·L^-1,在该条件下,Cu²⁺吸附率达85.84%,吸附量为128.74 mg·g^-1;其对Cu²⁺的吸附符合准二级动力学方程和Freundlich等温吸附模型;采用曝气挂膜法将细菌固定于多孔陶瓷上,形成的菌膜对50 mg·L^-1铜离子的吸附率达92.53%。表明细菌BX对Cu²⁺有较强的吸附能力,对含Cu²⁺废水的处理具有良好的应用前景。

Isolation and Cu2+ biosorption of metal-tolerant bacterium

The metal-tolerant bacterium strain BX,was isolated from polluted soils.The result of 16S rDNA sequence analysis indicated that the bacterium was Providencia alcalifaciens.The adaptability of bacterium BX to surroundings was discussed.The effects of the adsorption conditions,such as pH and temperature on the adsorption capacity by the bacterium BX from aqueous solutions were also investigated. Kinetic and isothermal study of BX toward Cu²⁺ was carried out.Immobilization was performed taking porous ceramics as carrier.The results showed that the bacterium BX could tolerant 7 mmol·L^-1 of Cu²⁺ and 7.5% of NaCl,and its growth was observed at conditions of pH4.0-11.0 and 15-50℃.The bacterium BX removed 85.84% of Cu²⁺ after 240 min of incubation in a solution containing 100 mg·L^-1 of Cu²⁺ at pH5.5,and the adsorption capacity of Cu²⁺ reached 128.74 mg·g^-1(dry bacterium).Kinetic study showed that the pseudo-second-order kinetic model fitted well with the experimental data whereas intraparticle diffusion could not be ignored,suggesting a chemical reaction mechanism.This would indicate that the adsorption of Cu²⁺ is a complex mix of surface adsorption occurring in the boundary layer of the bacterial particle and intraparticle diffusion.The isotherm biosorption of BX toward Cu²⁺ was in accordance with the Freundlich model,suggesting that the adsorption process followed a monolayer sorption.After the formation of biofilm on the porous ceramics,the adsorption rate of BX on 50 mg·L^-1 copper ion solution reached 92.53%.The experimental results demonstrated the potential application of the tested bacterium BX in the treatment of heavy metal wastewater for the strong adsorption under a wide range of environmental conditions.