氧化沟水力特性对处理效果和能耗的影响

Hydrodynamic Effects of the Oxidation Ditch on the Removal Efficiency and Energy Consumption

氧化沟水力特性对沟内溶解氧浓度和混合液流速梯度分布影响很大,可对最终的处理效果和能耗产生重要的影响.以处理能力500 m3/d的单沟型Passver氧化沟为例,对沟内的流场分布进行了计算模拟与实测,提出了改善氧化沟水力特性的措施,并分析了改善措施对运行能耗的影响,结果表明,在曝气转刷下游的弯道处分别设置张角90°,150°,180°的导流墙均可降低局部阻力,且随着张角的增大,效果越为显著,当张角为180°时,可降低局部能耗10%左右;在转刷转速72 r/min的条件下,增设张角180°的导流墙不会对溶解氧的分布产生较大影响.根据氧化沟处理低浓度生活污水的实际运行结果,采用活性污泥模拟软件对水力特性改善前后的处理效果进行了模拟计算,结果表明,设置导流墙前后出水水质变化不大.

The hydrodynamic characteristics in the oxidation ditch have great effects on the distributions of the dissolved oxygen and the velocity gradient, and then make important effects on the removal efficiency and energy consumption. The single-ditch Passver oxidation ditch with the capacity of 500 m^3/d was investigated. The measurement and computer simulation were carried out on the velocity gradient and the ways to improve the hydrodynamic characteristics were pointed out. Furthermore, its effect on the energy consumption was discussed. The results showed that the local resistance could be decreased by installing the guided wall with opening angle 90°, 150°, 180° ,respectively, which lied on the corner of the downriver of the aerator. The local energy consumption could be decreased by 10 % after the guided wall with 180° opening angle was installed. Under the condition that the velocity of the aerator was 72 r/min,the installation of the 180° guided wall could not effect the distribution of DO concentration. According to the operation results of treating the municipal wastewater with low concentration, the IAWPRC model was used to simulate the water qualities in the oxidation ditch with the 180° guided wall or not ,respectively. The simulation results showed that the water qualities in the effluent didn＇t change a lot after the 180° guided wall installed.