ผลของคลื่นเหนือเสียงต่อการกรองระดับจุลภาคในเครื่องกรองแบบหมุน / พุธพรรณ จรูญรัตน์ = Effects of the ultrasonic wave on microfiltration in a rotating filter / Phutphan Charoonrat
This present research is an application of ultrasound in the rotating filter micorfiltration system. The objective of this work is to reduce the rate of agglomeration of filtered particles on the membrane surface thoroughly in order to enhance the filtration efficiency without an increase of the number of the ultrasonic transducers. Ultrasound is pronounced by the reduction of the filtration resistance with the phenomenon called the cavitation and the turbulent movement of the fluid. These phenomenon have resulted in the removal of the particles deposited on the membrane surface within the area of which is radiated by ultrasound. To optimize the number of the ultrasonic transducers used to cover the whole area of the membrane surface, the rotating filter coupling with an ultrasonic transducer on the outside cylindrical wall is thus implemented. The factors affecting the filtration flux of the rotating filter system with ultrasound have been studied i.e. the baker's yeast solution 5, 10 and 20 g/l, the transmembrane pressure 0.22, 0.35 and 0.46 bar, the ultrasonic intensity 0.44, 1.76 and 3.09 w/cm2, the rotation speed 0-100 rpm. It has been found that in this system there is no effect from the shear force caused by the Taylor vortice of which would reduce the cake formation and consequently an increase of the flux. The experimental results have shown that the rotation speed has also no effect on the steady-state flux. It is also found that under ultrasonic irradiation the filtration flux is increased by 2 times with the rotating filter compared with the case without the rotation. The less the feed concentration, the more the effect of the ultrasonic on the flux. An increase of the ultrasonic intensity affects on the increase of the effect of the cavitation in the removal of the particles deposited on the membrane. An increase of the transmembrane pressure also enhances the flux under an ultrasonic irradiation. From the experimental results, it is found that the optimum condition is at an ultrasonic intensity 3.09 W/cm2, the feed concentration 10 g/l, the transmembrane pressure 0.46 bar, the speed rotation of 5-100 rpm, the flux can be increased by 3-5 times when compared with the case without ultrasonic and rotation. In the range of the studied ultrasonic intensity, the effects of ultrasonic on the percent rejection of the membrane and the characteristics of yeast have not found.
