Publication Details (including relevant citation information):
J. Environ. Eng., ASCE. 2010, 136(5), 501-507.
To optimize the design parameters of rectangular primary settling tanks, we used two-dimensional laser Doppler velocimetry (2D LDV) to conduct flow field measurements in five cases and used a previous model to simulate the flow field. The relative baffle submergence height and the ratio of tank length to height were optimized in a low suspended solid (LSS) concentration (LSS<150–200 mg/L). The experimental and simulation results show that a large recirculation zone exists behind the reaction baffle and the flow magnitude is small in the recirculation region; the length of recirculation increases with an increasing flow rate; the length of recirculation increases as the depth of the submerged reaction baffle increases; and the variation of the reaction baffle height can affect the flow field more significantly than does the variation of the flow rate. We also determined that to reach a higher removal rate and to optimize the area dimensions of a sedimentation tank, a length-to-height design ratio between 8 and 12 is optimal.