【作者】 章晶晓；

【导师】 陈建孟；

【作者基本信息】 浙江工业大学 ， 环境工程， 2009， 硕士

【摘要】 本研究首先以Methylibium petroleiphilum PM1菌降解甲基叔丁基醚(MTBE),分析其降解的特性和机理。结果表明,所采用的PM1菌在降解MTBE的过程中需要有氧气的参与,较适宜的pH值为7.0。当细胞浓度为0.92g/L时,47mg/L的MTBE能在3h内降解完全,显示了PM1菌较高的代谢能力。在初始细胞浓度为3.1×10~6cells/mL的反应体系中,检测到叔丁醇(TBA)、2-羟基异丁酸(HIBA)和甲酸等中间产物,并且推测之前文献大量报道的异丙醇可能不是MTBE的代谢中间产物。此外,研究发现通过在反应培养基中添加酵母粉、牛肉膏、胰蛋白胨等传统有机生长基质可以促进MTBE的降解。以颗粒活性炭吸附水相中MTBE的实验结果表明,本研究所采用的颗粒活性炭对MTBE有较高的吸附容量,Langmuir和Freundlich等温吸附线模型均可以较好的拟合其吸附,在活性炭浓度为1g/L时,静态最大吸附容量为204.1mg/g。通过对颗粒活性炭吸附MTBE的过程分析,表明在吸附初始阶段,表面扩散是吸附速率控制步骤。当活性炭表面吸附的MTBE达到一定量后,颗粒内扩散成为整个吸附过程的速率控制步骤。在菌浓度为0.12g/L的条件下,活性炭再生率为52.9%,微生物连续降解化合物的作用,使得被吸附化合物不断从颗粒活性炭中解吸出来,使吸附位再次打开,构成了吸附和降解的协同作用。最后,建立上流式固定床反应器,以颗粒活性炭做为挂膜载体和吸附剂,研究吸附-生物降解协同去除MTBE的过程。通过活性污泥挂膜和纯菌挂膜两种方式的比较,发现以PM1纯菌挂膜的反应器对MTBE的去除效果较好。虽然该方法的挂膜时间较长,但是其去除率并不低,在挂膜前期,活性炭可以发挥其对MTBE的高效吸附作用,以弥补PM1菌浓度不高导致的低降解效率。反应器挂膜成功后稳定运行,去除效率维持在90%以上,在出水中检测到了MTBE生物降解过程中重要的中间产物TBA。应用PCR-DGGE指纹图分析,表明反应器在稳定运行过程中微生物种群结构基本未发生变化,PM1为优势降解菌,其数量有所增加,并且发现添加酵母粉可以提高反应器中MTBE的去除率。更多还原

【Abstract】 Biodegradation of MTBE by Methylibium petroleiphilum PM1 was investigated in this paper.The results showed that the optimum pH was 7.0 for PM1 and oxygen was essential to the degradation.In the reaction system with cells of 0.92g/L,47mg/LMTBE could be degraded completely in three hours which reflected the high metabolic capability of PM1.The intermediates such as ter/-butyl alcohol(TBA),2-hydroxy isobutyrate (HIBA) and formic acid were detected during MTBE degradation.It was presumed that isopropanol was not the intermediate of MTBE degradation. Furthermore,the degradation of MTBE could be enhanced by the addition of readily metabolizable organic substrates such as yeast extract,beef extract and tryptone.The adsorption equilibrium and kinetics of MTBE onto granular activated carbon(GAC) have been studied in the present work.The equilibrium data could be fitted by both the Langmuir isotherm model and the Freundlich isotherm model which reflected that GAC had good capacity adsorbing MTBE.The maximum sorption capacity of GAC for MTBE was 204.1mg/g.Analysis of mechanism revealed that at the initial stage of adsorption,external mass transfer was the main rate controlling step.When the amounts of organic molecule which have reached external activated carbon increased to a certain degree,the sorption process became intraparticle-diffusion-controlled.In the solution with cells of 0.12g/L,the regeneration rate of activated carbon was 52.9%.The biodegration by PM1 made MTBE desorb from GAC,so the adsorption sites opened again forming the function of adsorption cooperated with biodegration.The packed-bed reactor with GAC to degrade MTBE continuously was developed.Compared with the two bio-membrance treatments respectively using activated sludge and pure strain of PM1,it was found the reactor with pure strain of PM1 could remove MTBE more efficiently. Though this treatment required more time before the membrane started up successfully,the removal rate was still high,because the GAC could adsorb MTBE efficiently when the cells concentration was low.The removal rate kept above 90%since the biomembrane hung up successfully and TBA was deteceted in the effluent water.The result of microbial community DNA profiling determined by denaturing gradient gel electrophoresis(DGGE) indicated that PM1 was the predominant bacterium during the whole stable operation.Moreover,the removal rate of the reactor could be advanced by the addition of yeast extract.更多还原