新型微米曝气设备的研制及其性能

Development of a new microbubble system and its performance

引言 曝气是污水生物处理系统的一个重要工艺环节，其主要作用是向反应池内充氧，保证微生物好氧代谢所需的溶解氧，并保持反应器内的混合和物质传递，为微生物培养提供必要的条件。曝气也是污水生物处理系统中运转费用最高的工艺环节，曝气充氧电耗一般占总动力消耗的60％～70％。目前的好氧曝气方法普遍存在效率低、成本和能耗高的问题。

Microbubbles are defined as bubbles with diameters less than 50 μm.Microbubbles have many advantages,such as huge interfacial area,low rising velocity in liquid phase,high inner pressure and fast dissolution.In this study,an accelerator was developed,and a system consisted of a conventional water pump and the accelerator was used as a microbubble aerator,with the expectation that it could be low in cost and easy to scale up.The produced microbubbles had a mean count diameter of less than 40 μm.In the experiments of 20 L volume,when the liquid flow rate was 20 L·min-1 and the gas flow rate was 2.67 L·min-1,the mass transfer coefficient of oxygen was more than 1.7 min-1 and the oxygen utilization efficiency was higher than 42%.Higher temperature was good for the mass transfer from the gas phase to the liquid phase.In the pilot-scale study of 90 L volume,a mass transfer coefficient of more than 0.18 min-1 and an oxygen utilization efficiency of more than 27% were achieved at a liquid flow rate of more than 14 L·min-1 and the gas flow rate of lower than 2 L·min-1.Compared with the Nikuni system,this system allows higher gas flux,generates smaller microbubbles,consumes less energy and performs better in mass transfer and oxygen-supply capacity.