CAJ | 학술논문

该文采用粒子图像测速技术研究了1、1.5、2.5 mm 3种不同曝气孔径下不同曝气强度对近膜面流场特性的影响规律，试验中分别研究了以上3种曝气孔径在所给定不同曝气强度下近膜面湍流强度值和液相平均速度值的变化规律。结果表明：近膜面液相平均速度值随曝气强度的增加呈现出先增大后趋于稳定的变化趋势。当曝气强度在24～140 L/h范围内时，湍流强度值随曝气强度呈正相关变化；曝气强度为140 L/h时，随曝气孔中心轴线高度的增大，湍流强度处于高低起伏的波动变化状态，这种波动更有利于膜污染的控制。因此，在此试验条件下最佳曝气强度为140 L/h。该研究为优化膜生物反应器内流场进而改善膜污染提供了一定的理论依据。
해문채용입자도상측속기술연구료1、1.5、2.5 mm 3충불동폭기공경하불동폭기강도대근막면류장특성적영향규률，시험중분별연구료이상3충폭기공경재소급정불동폭기강도하근막면단류강도치화액상평균속도치적변화규률。결과표명：근막면액상평균속도치수폭기강도적증가정현출선증대후추우은정적변화추세。당폭기강도재24～140 L/h범위내시，단류강도치수폭기강도정정상관변화；폭기강도위140 L/h시，수폭기공중심축선고도적증대，단류강도처우고저기복적파동변화상태，저충파동경유리우막오염적공제。인차，재차시험조건하최가폭기강도위140 L/h。해연구위우화막생물반응기내류장진이개선막오염제공료일정적이론의거。
This study built the test system of membrane surface flow field. The system was built under the condition of photo-metric optical fiber instead of hollow fiber membrane filaments. The paper analyzed the affection regularity of aeration intensity to fluid mechanics characteristics of hollow fiber membrane surface under the condition of clear water and three different aeration pore sizes of 1, 1.5, 2.5 mm based on the particle image velocimetry (PIV) technology. Further experiments were carried out on the variation of turbulence intensity values of hollow fiber membrane surface and liquid velocity values under the condition of different aeration intensities for three different aeration pore sizes. The movement of continuous phase (liquid) in PIV technology was marked by fluorescent particles to identify the velocity field of liquid. Under the conditions of this experiment, the trajectory of the bubble itself could reflect its velocity vector substantially, and the velocity field of each phase can be obtained after the phases were separated when we used the image processing techniques of each single phase. The results indicated that the increasing range of the average liquid velocity on the surface of the membrane appeared to be the highest when the aeration intensity was 140 L/h;and when over 140 L/h, it decreased to be much lower, so under the condition of this experiment, the optimum aeration intensity is 140 L/h, and more optimal turbulence intensity values are corresponding to this aeration intensity. In the project, according to optimized parameters, we can not only save the cost of system operating, but also eliminate the cake layer on the membrane surface and reduce the concentration polarization on both sides of the membrane surface. Under the condition of three different aeration pore sizes, the average speed of the liquid near the membrane surface is basically consistent with the aeration intensity;when the aeration is at 1 mm aperture, the velocity vectors of liquid near the surface of the membrane increase with the increase of aeration intensity, when the aeration intensity is over 140 L/h, the liquid velocity vectors near the membrane surface are basically the same;at lower aeration intensity, the liquid velocity of the membrane surface near the aeration pore is significantly higher than the ones which locate other places, and the liquid appears the phenomenon of rocking after affected by the bubble rising trajectory; at higher aeration intensity, liquid velocity value increases significantly in the horizontal direction; with the increase of the liquid velocity, the ranges of membrane filaments influenced correspondingly increase; and when the aeration intensity reaches 140 L/h, 6 membrane filaments are influenced at different degrees, and the shaking of the bubbles causes the rocking of the membrane filaments, which can play an active role in controlling the pollution of the membrane. This research provides a theoretic foundation for the optimization of flow field in membrane bioreactor so as to improve the membrane fouling problem.