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용존공기부상법 ( DAF ) 에서 미세기포와 입자간 충돌이론의 실험적 증명
독고석(Seok Dockko),한무영(Moo Young Han),박중현(Chung Hyun Park),남기진(Ki Jin Nam) 한국물환경학회 1999 한국물환경학회지 Vol.15 No.2
In this research, the theoretical modeling of DAF which was obtained by trajectory analysis has been verified. Especially, the effects of electrostatic nature and particle size of bubble and particle (floc) was focused. To measure the electrostatic nature of bubble, zeta potential measuring setup was made in a well controlled laboratory. The effects of several operational parameters in DAF process are investigated on a system composed of batch DAF reactor, microscope and video system. The effect of pH on the removal efficiency of DAF is presented. The effect of mixing time is presented. The effect of zeta potential of floc and bubbles with the addition of coagulant is presented. It is found that all the phenomena can be explained primarily from the electrostatic nature of bubble and particle and secondarily from the effect of particle size. The findings from this research are compared and verified with the results of DAF modeling by α_(bp). This research will be helpful to understand and explain the process better and possibly can be used to modify and improve the DAF process.
독고석,곽동희,김영환 대한상하수도학회 2004 상하수도학회지 Vol.18 No.2
The dissolved air flotation(DAF) process has been widely used for removing suspended solids with low density in water. It has been known as measuring the size of microbubbles precisely which move upward rapidly in contact zone is difficult. In this study particle counter monitoring (PCM) method is used to measure the rising microbubble after injection from a nozzle. Size and distribution curve of microbubbles are evaluated at different conditions such as pressure drop at intermediate valve, length of pipeline between saturation tank and nozzle and low pressure. And the efficiency is also checked when it collides with different size floc. The experimental results show the following fact. As the final pressure drop occurred closer to a nozzle, the bubble size became smaller. And small bubble collides with large floc as well as small one because of its physical characteristic. However large bubble collides well with large floc rather than small one since hydrodynamic flow in streamline interferes to collide between two. With performing computational process by mathematical model we have analyzed and verified the size effect between bubble and floc. Collision efficiency is the highest when P/B ratio shows in the range of 0.75 < P/B ratio (R_(particle/Rbubble)) < 2.0.