【作者】 纪志永；

【导师】 李鑫钢；

【作者基本信息】 天津大学 ， 化学工程， 2007， 博士

【摘要】 膜气提(Membrane Air Stripping,MAS)及生物强化技术对治理与修复水体挥发性有机物(Volatile Organic Compounds,VOCs)污染具有较大的优势和广阔的前景。MAS是一种新兴的水污染修复技术,适于处理含各种浓度范围的VOCs污染水体,从经济角度考虑更宜处理较高浓度污染水体;生物强化处理含VOCs浓度较低的污染水体更为绿色经济。本文以VOCs中典型且难处理的甲基叔丁基醚(Methyl Tert-Butyl Ether,MTBE)污水体系为主要修复对象,从MAS去除MTBE和生物强化去除MTBE两个方面进行了系统研究,并结合它们的特点对MAS与生物强化复合去除MTBE进行了研究。根据连续性方程、动量方程和传质方程,建立了MAS过程的二维轴对称数学模型。MAS去除MTBE的实验研究表明:系统温度升高、气液流速增大均能有效促进对MTBE的去除;MTBE初始浓度和气液相压力对去除效果影响很小。模拟结果与实验数据基本吻合,说明该模型能够描述MAS去除MTBE的过程。MAS过程也具有膜供氧效果,二者可同步操作。在理论上对氧传质过程进行了四步划分;当气压大于液压时,微气泡层存在且对供氧效果产生影响;氧的体积传质系数在一定条件下随气相操作压力的升高而增大。通过对被石化产品污染土壤中的土著微生物进行驯化、分离,得到一株降解MTBE的优势菌株NERC0401,根据菌株形态特征和16S rDNA测序结果,初步鉴定为产酸克雷伯菌(Klebsiella oxytoca)。它的较佳好氧降解条件为:接种量20%,pH 7.0~8.0,温度25~32℃。对该菌株的进一步强化研究表明:初始溶解氧的增大会增强对MTBE的降解去除效果;初始浓度一定的乙醇与MTBE共存时,会促进对MTBE的生物去除;经海藻酸钙包埋固定化的优势菌株对MTBE的去除效果显著提高,同时对污染水体pH和MTBE初始浓度的适应性增强。建立了MAS与生物强化复合工艺中固定床生物反应柱的一维数学模型。模型计算结果和实验数据表明,停留时间是影响生物去除效果的一个关键因素。模型对设计合理的生物装填柱长度与选取适宜的废水流量具有指导作用。MAS与生物强化复合去除水中MTBE的实验研究初步表明,复合工艺对去除水中VOCs是切实可行的,具有广阔的应用前景。更多还原

【Abstract】 Membrane air stripping (MAS) and bioenhancement technology are predominant and promising treatment methods for removing volatile organic compounds (VOCs) from wastewater. MAS is an innovatory removal and recovery technique which fits for treating VOCs contaminated water at a wide range of concentration, especially economic for high VOC levels, whereas bioenhancement technology is more clean and effective at low VOC concentrations. This study mainly focused on the removal of methyl tert-butyl ether (MTBE), which is one of the most typical VOCs, from model wastewater when membrane air stripping or/and bioenhancement involved.A two-dimension axial symmetry model was presented to describe mass transfer in the process of membrane air stripping based on equations of continuity, motion and mass transfer. The removal of MTBE from model water was studied using membrane air stripping. Results showed that the increase of temperature, air/liquid flux was helpful to the removal of dissolved MTBE, but the initial concentration, air/liquid pressure was hardly influenced on the the removal of MTBE. Simulation result was in good agreement with the experimental data.Oxygen dissolved into wastewater through membrane during the membrane air stripping process. As a result, oxygen supply and removal/recovery VOCs by membrane air stripping could be simultaneouslly performed using one setting. The course of oxygen transfer from air into water through membrane comprised four steps; the layer of micro-bubble could influence the effectiveness of oxygen supply when the pressure of air was larger than that of liquid; and the coefficient of oxygen mass transfer increased as air pressure increased.One stain NERC0401 identified as Klebsiella oxytoca that could degrade MTBE quickly was isolated by enriching, screening and culturing from the soil at Dagang Oil Field, Tianjin, China, and the proper conditions for MTBE aerobic biodegradation were determined by experiments. The bioenhancement results showed that the enhancement of dissolved oxygen (DO) could improve the biodegradation of MTBE by strain NERC0401, and the coexiting of ethanol at some concentrations was helpful for the process. In addition, the degradation ability of NERC0401 could be improved when the microbe was immobilized by calcium alginate.A one-dimension model of column filled with immobilized microbe, which was used as one part of combined technics of membrane air stripping and bioenhancement, was developed for forecasting the removal of MTBE. Simulation results fitted well with the experimental data, and the residence time was a key factor for MTBE biodegradation. This study will be useful for treating VOCs contaminated water by using the combined technics.更多还原