【作者】 张瑞玲；

【导师】 李鑫钢；

【作者基本信息】 天津大学 ， 化学工程， 2007， 博士

【摘要】 甲基叔丁基醚(Methyl tert-Butyl Ether,MTBE)作为一种汽油添加剂,广泛应用到汽油当中,其对土壤地下水环境造成的危害已引起人们的高度重视。生物修复是一种MTBE有效去除的环境治理技术。本论文在获得MTBE高效降解菌株的基础上,系统深入地研究了MTBE的降解特性、降解机理及生物修复中微生物的迁移规律。本文从MTBE污染场地中筛选获得优势降解菌株A-3,经鉴定该菌株为Chryseobacterium sp.细菌,该菌株的获得为MTBE的降解提供了新的菌源。在此基础上,研究了该菌株降解MTBE的最佳环境条件如温度、pH值、接种量、溶解氧以及底物浓度等;通过比较Chryseobacterium sp. A-3在葡萄糖和MTBE为碳源培养基中的生长情况,分析了菌株在MTBE中生长缓慢的原因;并进行了MTBE生物降解的矿化率实验来解释该分离菌对MTBE的降解能力。为了更深入了解MTBE的降解机理,采用SPM-GC-MS方法对生物降解MTBE的中间产物进行了检测。研究了中间产物TBA对MTBE降解的影响,分析了生物降解MTBE与TBA过程中关键酶系的异同。粗蛋白SDS-PAGE分析结果表明MTBE与TBA诱导出均有7条相同蛋白带的细胞蛋白图谱。降解质粒的提取与消除实验证实MTBE的降解基因存在于染色体上而非质粒上。为了进一步提高MTBE的生物降解能力,研究了环状糊精对MTBE生物降解的促进作用。通过非烷烃物质对MTBE共代谢的研究得出,适当浓度的丙三醇能够有效共代谢MTBE。这些都为MTBE的去除提供了新的方案。另外还考察了该菌的环境适应性以及环境中BTEX对MTBE降解的影响。为了使生物修复更好地应用于现场,研究了微生物在土壤地下水环境中的迁移规律及影响因素。对微生物的吸附过程提出了吸附双过程模型,对模型进行了实验验证并考察了流速与微生物浓度对吸附过程的影响。在此基础上,以污染物作为限制底物,综合考虑了降解菌的吸附、解析、生长、衰亡以及底物的迁移转化,建立了迁移规律理论模型。应用此模型描述了微生物在生物修复中的迁移过程,比较了微生物与污染物的迁移特点。更多还原

【Abstract】 Methyl tert-butyl ether (MTBE) is widely used in gasoline additive and causes severe environmental pollutions. Recently, it attracts more attention due to its toxic and recalcitrant properties in the environment. Compared with conventional methods, biodegradation is more economical and effective for the remediation of MTBE pollution. In this study, a bacterial culture possessing effective degradation ability was isolated. Based on which, the systematical studies on the degradation characteristics, mechanism and bacterial transport in the bioremediation process were carried out.A bacterial culture named A-3 which could effectively degrade MTBE was isolated from the MTBE contaminated soil. It was identified as Chryseobacterium sp., a new species capable of degrading MTBE. The effects of environmental factors such as temperature, pH values, inoculating sizes and MTBE concentrations on MTBE degradation were optimized. The ability of this isolate growing in glucose and MTBE as carbon source was compared and the slow growth in MTBE was explained. The mineralization experiments of MTBE biodegradation were also conducted to estimate the ability of the isolate.To better understand of the mechanism involved in MTBE biodegradation, the main metabolic intermediates were determined by SPE-GC/MS analytical method. Furthermore, the effect of tert-butyl alcohol (TBA) on MTBE degradation was also investigated, and the difference of the key enzymes involved in biodegradation between MTBE and TBA was examined. SDS-PAGE analysis of the crude extracts obtained from the cells growing in MTBE and TBA cultures demonstrated that there presence seven similar peptides in both extracts. The experiments in plasmid purification and elimination further suggested that the degrading function might be controlled by chromosome DNA other than plasmid.In order to improve the degradation ability of Chryseobacterium sp.,β-cyclodextrin was used to enhance the MTBE degradation rate. The effects of cometabolic substrates on the degradation of MTBE were also explored and the results indicated that glycerol was the best cometabolic substrate to promote the degradation rate and shorten the period. All the mentioned researches give new approached for MTBE removing. To predict the behavior of MTBE, the adaptability of the isolate and the effects of BTEX on the degradation of MTBE were examined.In order to apply Chryseobacterium sp. into the bioremediation in MTBE contaminated site, the transport of bacteria in porous media and the influence factors were investigated. A mathematical model describing the adsorption with two fractions was proposed. Based on the model analysis and simulation, the effects of infiltration rate and bacteria concentration on transport were discussed. Moreover,a completely coupled model for microbial and substrate transport in soil were developed combining bacterial adsorption, desorption, growth and decay. The transport performances of Chryseobacterium sp. and substrate in the bioremediation processes were described.更多还原