Chang-Keun Wang

Effects of longitudinal baffles on particles settling in a sedimentation basin

This study was conducted to evaluate the effects of longitudinal baffles on particles settling performance within a full-scale sedimentation basin with a flow rate of 1,000 m(3)/hr. Comparative experiments on turbidity removal efficiency and sludge deposit distribution were performed in longitudinally baffled and non-baffled sedimentation basins. The turbidity removal rate in the baffled sedimentation basin was observed to be higher than that in the non-baffled basin. In addition, the depth of the sludge deposit in the baffled sedimentation basin was approximately 20% less than that in the non-baffled sedimentation basin, and the sludge concentration was 10% higher. To explain these results and to further investigate the effects of longitudinal baffles, the authors performed computational fluid dynamics (CFD) simulation for both basin types. The results of this CFD simulation indicated that the flow, particularly near the outlet orifice, was more stable in the longitudinally baffled sedimentation basin. Moreover, it could be concluded that the longitudinal baffle enables a fully developed flow and is thus more effective for sedimentation.

Process control system of granular media filter considering daily flow-rate fluctuation

AbstractIn this study, to investigate the influence of fluctuation in hydraulic loads on both the operation of filtration process and the quality of filtered water for a domestic water treatment plant, two different control methods were analyzed and compared with each other: (1) constant-rate filtration using a flow meter and a flow modulation valve (rate control method; RC method), (2) constant-level filtration using equal-flow splitting inlet weirs, water level sensors, and a flow modulator valve (level control method; LC method). From the results of experiments, it could be showed that a sudden flow surge may cause significant particle detachment in terms of particle count in filtered water under conditions of LC method. In addition, this method can lead to difficulty in maintaining residual chlorine at the outlet of clear well. On the other hand, the RC method, in two aspects – the process operation and the quality, is evaluated to be more appropriate than the LC method with seriously large fluctuatio...

Fluid Flow Characteristics for Minimizing the Area of Rapid Flow Inside the Water Tank to which the Multiple Hoe Screw Nozzle Incurrent Canal is Applied, by Using the Computational Fluid Dynamics (CFD) Simulation

This study was carried out for the purpose of minimizing the area of rapid flow inside the water tank. And the shape of incurrent canal was improved, and then the characteristics of fluid flow occurring inside the water tank was analyzed by using the Computational Fluid Dynamics (CFD) simulation method. better multiple hoe screw nozzle incurrent canal was used instead of conventional drop current canal used for the water tank. And according to the results of analyzing the characteristics of fluid flow, in case a screw blade was installed inside the nozzle, fluid flow was sprayed wide. And wide fluid flow was shown inside the cylindrical water tank too. Besides, a tracer simulation was carried out, in case of installing 1 and 2 multiple hoe screw nozzle incurrent canals at the cubic water tank. As a result, MODAL, MODAL index value was close to 1, in case of installing 2 canals. Therefore, it was possible to obtain the results of being close to the characteristics of plug flow.

Examining the Equality of Multi-Outlet Flow Rates within a Dual Open Channel

This study was conducted to qualify the equality of the flow distribution from open channel between rapid mixing basin and flocculation basins in a domestic S_ water treatment plant, and to suggest a remedy for improving the equality. In order to evaluate the feasibility of the suggested remedy, computational fluid dynamics (CFD) technique are used, and for verifying the CFD simulation results tracer tests were carried out. From the results of CFD simulation and tracer tests, it was investigated that the modification of hydraulic structure in the distribution channel, which is to install the longitudinal orifice baffle in flow direction, could improve the equality of the flow distribution over 75%.