循环推流式固定化微生物反应器的设计及优化研究

发布时间：2018-01-02 13:33

本文关键词：循环推流式固定化微生物反应器的设计及优化研究　出处：《广西大学》2015年硕士论文　论文类型：学位论文

【摘要】：城镇生活污水是一种潜在的水资源,对其净化处理并再利用,既能减轻水体污染程度,改善生态环境,又能解决城镇的缺水问题。固定化微生物技术因其独特的优越性成为污水处理及环境保护领域的研究热点。然而现有的固定化微生物反应器不适用于较为分散、难以收集且多滞留在水深较浅的湖塘、水洼等区域的城镇生活污水。针对广西壮族自治区宁明县爱店村某生物氧化塘污水处理项目,尝试研发设计一种循环推流式固定化微生物反应器。主要包括反应器筒体设计、固定化微生物载体的选择以及曝气系统的设计。反应器内流场的流体力学行为十分复杂。通过对气-液-固三相模型的简化、气液两相流的形态研究、气-液相间氧的传质以及循环推流原理分析,有助于明确影响反应器性能的设计参数,为进一步改善和优化反应器的结构提供依据。根据曝气头安装高度分别为650 mm,750 mm,850 mm,定义方案A、B、C为三种不同结构反应器。利用计算流体力学软件Fluent 6.3对反应器内部流场进行数值模拟。通过对流体速度云图、速度矢量图以及液相出口速度分布图进行分析,结果表明方案A中曝气头上方出现大的漩涡,且液相流速小于0.25 m·s1；方案C中曝气产生的轴向力不能充分带动液相流上升,且二分之一出口面积的液相速度小于0.05 m·s-1；方案B既有充足的升程供空气与水之间的氧的传质,又有较高的液相出口速度保证流体的循环。因此方案B是最佳方案,即最佳曝气安装高度为750 mm。同样方法对曝气量不同的方案B、D、E进行数值模拟,其模拟结果为方案E,即曝气量为0.5 kg·h-1 时,液相出口速率最大,有利于流体循环。为验证数值模拟结果的准确性和可靠性,设计一套试验方案：以清水作为试验对象,利用Na2SO3作为还原剂进行消氧,CoCl2作为催化剂加快消氧速率。由不同曝气头安装高度的溶解氧变化曲线图可知,与方案A和方案C相比,方案B充氧速率较快；由不同曝气量的的溶解氧变化曲线图可知,方案E的充氧速率最快。实验结果均与数值模拟结果一致。将优化后的反应器置于氧化塘内运行,经过30天的水质监测,水体中化学需氧量浓度(COD)从58 g·m-3下降到14 g·m-3,总磷浓度从0.76 g·m-3下降到0.19 g·m-3。氨氮浓度虽然有一定的波动,但整体呈下降趋势,从11g·m-3降至7 g·m-3。氧化塘内鱼类大面积死亡现象消失,恶臭味道不在,水藻横生的状况解决,整个水体中的生物圈体系得以改善,提升了氧化塘的自我降解能力。
[Abstract]:Urban domestic sewage is a kind of potential water resources. Purifying it and reusing it can not only reduce the pollution degree of water body, but also improve the ecological environment. Immobilized microorganism technology has become a research hotspot in the field of sewage treatment and environmental protection because of its unique advantages. However, the existing immobilized microbial reactor is not suitable for dispersion. It is difficult to collect and stay in shallow lake ponds, water pools and other areas of urban domestic sewage. Aiming at a biological oxidation pond sewage treatment project in Edian Village, Ningming County, Guangxi Zhuang Autonomous region. This paper attempts to develop and design a circulating push-flow immobilized microbial reactor, which mainly includes the design of reactor cylinder. The selection of immobilized microorganism carrier and the design of aeration system. The hydrodynamic behavior of the flow field in the reactor is very complicated. By simplifying the gas-liquid-solid three-phase model, the morphology of gas-liquid two-phase flow is studied. The mass transfer between gas and liquid phase and the analysis of circulation pushing principle are helpful to clarify the design parameters that affect the reactor performance. In order to further improve and optimize the reactor structure, according to the aeration head installation height of 650 mm 750mm / 850mm, defined scheme AHB. C is three kinds of reactors with different structures. The flow field in the reactor is simulated by the computational fluid dynamics software Fluent 6.3. The flow velocity cloud diagram is used to simulate the flow field in the reactor. The velocity vector diagram and the velocity distribution chart of liquid phase exit are analyzed. The results show that there is a large vortex above the aeration head in scheme A, and the liquid velocity is less than 0.25 m 路s ~ (-1). The axial force produced by aeration in scheme C can not fully drive up the liquid phase flow, and the liquid phase velocity of 1/2 exit area is less than 0.05 m 路s-1; Scheme B not only has sufficient lift for oxygen transfer between air and water, but also has high liquid phase exit velocity to ensure fluid circulation. Therefore, scheme B is the best scheme. The best aeration installation height is 750 mm. the same method is used to simulate the different aeration rate scheme BGDNE, the simulation result is scheme E, that is, when the aeration rate is 0.5 kg 路h ~ (-1), the simulation results are as follows: (1) the best aeration installation height is 750 mm 路h ~ (-1). In order to verify the accuracy and reliability of the numerical simulation results, a set of test scheme is designed: water is taken as the test object. Na2SO3 was used as reducing agent to deoxidize oxygen and CoCl2 was used as catalyst to accelerate the deoxygenation rate. According to the curves of dissolved oxygen with different aeration heads, it was compared with schemes A and C. The oxygenation rate of scheme B is faster; According to the dissolved oxygen curve of different aeration rate, the oxygen filling rate of scheme E is the fastest. The experimental results are consistent with the results of numerical simulation. The optimized reactor is put into the oxidation pond to run. After 30 days of water quality monitoring, COD) decreased from 58 g 路m -3 to 14 g 路m -3. Total phosphorus concentration decreased from 0.76 g 路m -3 to 0.19 g 路m -3. From 11g 路m-3 to 7g 路m-3.The phenomenon of fish death disappeared in the oxidation pond, the odor was not found, and the algal growth was solved, and the whole biosphere system in the water was improved. Improved the oxidation pond self-degradation ability.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;X172

【参考文献】