Study Of Enhanced Ozone Mass Transfer Technology Based On Microbubble

The drinking water treatment plant adopting O3-BAC process now are usingporous aeration plate for ozone contact. To reach high ozone absorptivity, the ozonationcontact tank are designed deep, which increases the structure construction costs, ozoneequipment investment and operation costs. The problem limits the development ofO3-BAC technology. Therefore, efficient new ozone contact technologies are neededwhich have important theoretical significance and practical value.This study was designed to evaluate the bubble diameter distribution, the apparentmass transfer coefficient of ozone, the ozone absorption rate and utilization rate and theorganic matter removal efficiency in ozone microbubble contact way and traditionalcontact way. Also compared the strengths and weaknesses of two kinds of ozone contactway.Based on this study, the following conclusions were drawn:(1) With the water flowrate rising from10L/min to15L/min, the sauter mean diameter of bubbles increasesgradually and the apparent mass transfer coefficient of ozone increases from0.16min-1to0.22min-1in microbubble contact way.(2) With the water depth rising from1.0m to2.0m, the sauter mean diameter of bubbles decreases gradually and the apparent masstransfer coefficient of ozone increases from0.20min-1to0.26min-1in microbubblecontact way.(3) When the water flow rate is15L/min and the water depth is2.0m, thesauter mean diameter of microbubbles generated in microbubble contact way isone-tenth of that bubbles generated in traditional contact way. Besides, the apparentmass transfer coefficient of ozone in microbubble contact way is about2.4times that ofthe traditional contact way.(4) In both microbubble contact way and traditional contactway, ozone absorption rate and utilization rate decrease with the increase of ozonedosage, increase with the increase of empty bed contact time(EBCT), and the ozoneabsorption rate also increase with the increase of water depth. The highest ozoneabsorption rate can be99.42%and the highest ozone utilization rate can be95.55%inmicrobubble contact way. On the other hand, the highest ozone absorption rate can be86.82%and the highest ozone utilization rate can be77.26%in traditional contact way. (5) In the water depths1.0~2.0m, EBCT1.2~5.0min or ozone dosage0.5~2.0mg/L,the organic matter removal efficiency of microbubble contact way is higher than that oftraditional contact way. The highest discrepancy of CODMnremoval rate can be24%.And the highest discrepancy of average unit ozone dosage of CODMnremoval can be2.5mg/mg.