Effects of Liquid Level on Velocity Distribution of Fluid in Multi-Flora Biological Wastewater Treatment Reactor

The flow characteristics and effects of liquid level on velocity distribution of the fluid in main reaction zone of multi flora biological wastewater treatment reactor were studied with clean water. Experimental results demonstrated that the fluid in main reaction zone formed non-symmetrical cycle flow in the vertical plane with lower flow velocity in the central area and higher flow velocity in the peripheral area under the lifting action of the bubbles from perforated aerated pipe. As the liquid level varied from h=525 mm to h=55 mm, the position and the flow rate of the central zone with lower velocity in the main reaction zone had not changed distinctly; With the decrease of liquid level height, the scope of water circulation decreased in the main reaction zone, but the velocity gradient from the center to the left and right increased gradually, and velocity distribution in the horizontal direction appeared the more obvious non symmetry. For the design and operation of multi-flora biological wastewater treatment reactor, the results had important guiding significances that were listed out.