Improving flow distribution in influent channels using computational fluid dynamics

Abstract

Although the flow distribution in an influent channel where the inflow is split into each treatment process in a wastewater treatment plant greatly affects the efficiency of the process, and a weir is the typical structure for the flow distribution, to the authors' knowledge, there is a paucity of research on the flow distribution in an open channel with a weir. In this study, the influent channel of a real-scale wastewater treatment plant was used, installing a suppressed rectangular weir that has a horizontal crest to cross the full channel width. The flow distribution in the influent channel was analyzed using a validated computational fluid dynamics model to investigate (1) the comparison of single-phase and two-phase simulation, (2) the improved procedure of the prototype channel, and (3) the effect of the inflow rate on flow distribution. The results show that two-phase simulation is more reliable due to the description of the free-surface fluctuations. It should first be considered for improving flow distribution to prevent a short-circuit flow, and the difference in the kinetic energy with the inflow rate makes flow distribution trends different. The authors believe that this case study is helpful for improving flow distribution in an influent channel.

Numerical method and program for computing inlet flow distribution in sedimentation tanks

“…Flocculation units must receive flows distributed equally among the same units failing which those units with shorter retention time can experience floc break up and floatation of sludge [1]. An unusually long retention time in wastewater treatment units because of non-uniform flow distribution can result in large sludge age and sludge decay [2].…”

“…Practical observation showed that water treatment efficiencies were impaired as a result [7,8]. A more accurate three dimensional analysis such as using computational fluid dynamics (CFD) modelling would be able to handle complicated flow distribution geometry [2].…”