微曝氧化沟工艺污水处理的气泡羽流行为及流体动力学效应

The micro-porous aeration system is the core of the micro-porous aeration oxidation ditch. Its operation condition cooperated with flowmaker and the oxygen transfer efficiency in the ditch are the main factors of the final sewage treatment performance, and are directly associated with operation cost. This project aims at studying the motion law of the gas-liquid two phase flow in the non-Newtonian fluid and revealing the function mechanism of cross flow and Coanda effect on the movement of bubble plume. According to the measurement of dissolved oxygen concentration in the experimental oxidation ditch with water and CMC solution under the condition of various structure of bubble plume, the oxygen transfer coefficient is determined and the relationship among oxygen transfer efficiency, bubble plume property and plug flow strength is established in union of gas-liquid two phase flow simulation. In the actual operation condition, the spatial and temporal distribution of physicochemical properties and rheological property of mixed liquor is measured and oxygen uptake rate of biomass and oxygen transfer coefficient are calculated. Based on measured data, the model coupling multiphase flow model, dissolved oxygen transport model and activated sludge model is developed and verified. According to the measured data and simulated results, the effects of bubble plume on the distribution of dissolved oxygen and the effluent quality are revealed, and the resolution for improving the aeration performance and lower the energy cost is proposed.

微孔曝气系统是整个微曝氧化沟污水处理过程的核心，其与推流设备配合运行状态及沟道内氧转移效率的高低直接影响到最终污水处理效果，并与运行成本直接相关。本项目拟研究不同曝气条件下非牛顿流体中气液两相体系的运动规律，探明横向流动和附壁效应对气泡羽流的作用机制；通过对氧化沟实验装置内清水和CMC水溶液中不同气泡羽流运动特征条件下溶解氧溶度的时空分布的测量，确定氧的总转移系数，结合气液两相流模型模拟分析，确立氧传质效率与气泡羽流特征、推流强度等参数的关系；测量实际运行条件下污泥污水混合液理化特性和流变性时空分布规律，确定氧的总转移系数和微生物耗氧速率；根据获取的实验数据，建立并验证多相流模型、溶解氧输运模型和生化模型的耦合模型；分析实验数据和数值模拟结果，探明气泡羽流对氧化沟内溶解氧分布和出水水质的影响规律，提出改善微曝氧化沟曝气效率和降低能耗的解决方案。

微孔曝气系统是整个微曝氧化沟污水处理过程的核心，其与推流设备配合运行状态及沟道内氧转移效率的高低直接影响到最终污水处理效果，并与运行成本直接相关。本项目研究了不同曝气条件下非牛顿流体中气液两相体系的运动规律，探明了横向流动和附壁效应对气泡羽流的作用机制，确定了曝气盘在非牛顿流体中的布置方法；明确了全混流态下气泡羽流的运动规律、卷吸特性和传质规律。通过对氧化沟实验装置内清水和CMC水溶液中不同气泡羽流运动特征条件下溶解氧溶度的时空分布的测量，确定了氧的总转移系数，结合气液两相流模型模拟分析，确立了氧传质效率与气泡羽流特征、推流强度等参数的关系。建立减速微曝氧化沟中试实验平台，测量了实际运行条件下污泥污水混合液理化特性和流变特性，确定了微曝氧化沟内溶解氧的变化规律和污水处理的影响因素；根据获取的实验数据，建立并验证了气液两相流动、溶解氧输运模型和生化模型的耦合模型；分析实验数据和数值模拟结果，探明了气泡羽流对氧化沟内溶解氧分布和出水水质的影响规律，提出了改善微曝氧化沟曝气效率和降低能耗的解决方案。