A study on the Evenness Improvement of Influent Flow rates Distributed to Parallel-arrayed Grit chambers using CFD simulation technique

Abstract

Objectives : The objectives of this study are to assess the degree of uniformity of the flow rate flowing into four grit chamber for actual waste water treatment and to to improve hydraulic structure of the existing distribution channel.Methods : Mobile ultrasonic flow meter was used to measure each flow rate flowing into four grit chambers, and the CFD technique was used to suggest several hydraulic structure improvements for enhancing flow rate evenness.Results and Discussion : From the results of the actual measurement using ultrasonic flowmeter and CFD simulation, The flow rates distributed to four grit chamber through the existing complicated open channels (four outlets) showed a severe unevenness. It was revealed that the flow rate passing through the outlets 1 and 4 at both right anf left ends showed a difference of more than 20% compared to those through outlets 2 and 3 installed in the center.Conclusion : As a result of examining the data of the water level, flow rate, and distribution percentages passing through the 4 distribution channels using the CFD simulation, it was found that case 4 (the case to install the orifice walls on both sides) had the most even flow rate distribution effect. However, as a result of comparing the water levels in case 4 and case 6, the case installing both orifice walls make relatively higher head loss.