【作者】 焦妍；

【导师】 刘志军；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2011， 硕士

【摘要】 基质在生物膜内的质量传递过程是生物膜法污水处理技术的重要研究内容,是生物膜技术理论的本质和基础。随着科技的发展与理论的更新,这一领域被不断赋予新的研究内容。在前人研究成果的基础上,本文以生物膜多孔介质为研究对象,在生物膜传质模型中引入渗流理论,细化模型结构,通过数值模拟和实验研究的手段,对生物膜的传质过程进行了深入的研究,数值模拟结果与实验测试结果吻合较好。本文主要内容包括：1.将渗流理论引入生物膜内的质量传递过程,建立生物膜“对流-扩散-反应”模型。对生物膜模型进行分层处理,使模型物性参数更接近实际生物膜内的真实状态。采用Runge-Kutta法对传质模型进行数值求解,从而研究了不同进料液浓度和渗流速度,不同生物膜孔道弯曲因子和孔隙率条件下的生物膜内传质规律。结果表明：随着各参数值的逐渐增大,基质在生物膜内的渗透深度逐渐增加；进水浓度、生物膜孔隙率和渗流速度对传质影响较大,弯曲因子对基质的渗透影响较小。分层生物膜模型中基质渗透深度大于均一化生物膜模型的结果,分层模型对基质的传质阻力比均一化生物膜模型小。2.建立了一套10L的固定床好氧生物膜反应器实验装置,研究反应器中水力停留时间(HRT)、进水COD浓度和曝气量等参数对COD去除率的影响,同时利用微电极技术检测了不同参数条件下溶解氧在生物膜内的浓度分布规律。结果表明：较小的液相流速对生物膜内的传质过程影响不大,较高的COD浓度会增大生物膜内的耗氧速率,当COD=800 mg/L时,微生物生长不再受COD浓度的影响；实验测得反应器的最佳运行条件为：HRT=6-8 h,进水COD=600 mg/L,曝气量Qg=0.1 m3/h；3.根据批实验数据,拟合出反应器内底物基质的生物反应速率方程,得到氧的最大消耗速率为0.0099 min-1,半饱和浓度为6.94 mg/L；葡萄糖的最大降解速率为0.0095min-1,半饱和浓度为485.71 mg/L。用实验测得的参数对生物膜“对流-扩散-反应”传质方程进行分层处理并求解,得到生物膜内基质浓度的分布,计算值与实验值的误差在1.91%-18%之间,表明分层生物膜模型比均一化模型更符合实际传质情况,该模型可用于预测生物膜内的传质过程。更多还原

【Abstract】 The process of the substrates mass transfer in the biofilm plays a very important role in wastewater treatment technology using biofilm, which is the essence or basis of biofilm theory. With technology development and theory updates, this research field is constantly given new contents. Basing on previous work in this area, this thesis added percolation theory to mass transfer model within biofilm porous medium and make an intensive research of mass transfer process in biofilm by means of numerical simulation and experiment. The results of numerical simulation agree well with experimental results.The contents of this study include:1. Introduce percolation theory to the process of mass transfer within biofilm and build a "convection-diffusion-reaction" model. The model was stratified so that physical parameters of biofilm can be closer to actual situation, and numerically calculated by Runge-Kutta method. The influence of substrate concentration and seepage velocity, tortuosity and porosity to mass transfer within biofilm was investigated accordinglly. The numerical results showed that as the value of each parameter increased, the substrate penetration depth increased. Besides, most of these parameters had significantly influence on mass transfer within biofilm except the tortuosity. The substrate penetrates deeper into stratified biofilms than it does into homogeneous biofilms, the stratified biofilm model shows the lower mass transfer resistance to the substrate penetrate.2. A fixed-bed aerobic biofilm reactor of 10 L was established. The COD of effluent was monitored with HRT、COD of influent and aeration rate changing. The results show that smaller liquid flow rate has little effect on mass transfer within biofilm and higher COD influent concentration will increase the oxygen consumption rate of aerobic biofilm. When the value of COD reached to 800 mg/L, the COD was no longer the limiting factor for microbial growth.The best operating conditions in this experiment are listed as follows: HRT=6-8 h,COD in influent=600 mg/L, the aeration rate Qg=0.1m3/h.3. According to batch test data, the aerobic biofilm reaction rate equation was fitted, namely the largest oxygen consumption is 0.0099 min-1, half-saturation 6.94 mg/L, Glucose maximum degradation rate 0.0095 min-1, half-saturation 485.71 mg/L. Substrate concentration distribution within biofilm can be determined by numerically calculating mass transfer equcation with above-mentioned parameters. The error of the result between that obtained by stratified biofilm model and the convection-diffusion-reaction equation is 1.91%-18%. It was also verified that the stratified biofilm model is more suitable for actual mass transfer than the homogeneous biofilm model, thus can be used to predict the mass transfer process within the biofilm.更多还原