Intensification of Ozone Mass Transfer and Generation of Hydroxyl Radicals by Ceramic Membrane

ABSTRACT The strengthening ability of ozone to treat the reverse osmosis concentrate (ROC) of landfill leachate is a crucial issue. From the standpoint of coupling intensification, a ceramic membrane/ozone (CM/O3) system was developed to improve the oxidation performance of ozone. The results showed that CM/O3 system could significantly improve the ozone concentration and the generation of hydroxyl radicals (·OH) when compared to the traditional O3 bubble system. The reaction condition, such as inlet ozone concentration and ozone flow, ceramic membrane pore size, transmembrane pressure, and temperature on the concentration of ozone in the liquid phase and the formation of ·OH, has been considered. Experimental results showed that the concentration of ozone and OH in the liquid increased with the increase in the inlet ozone concentration and ozone flow. Moreover, a certain degree of reduction in membrane pores was facilitated to intensify the mass transfer of ozone. The increase of pressure was able to raise the concentration of ozone. However, there was a slight effect on ·OH concentration. As for the temperature, a low-temperature situation was conducive to strengthen ozone dissolution. In terms of the generation of ·OH, a high-temperature situation was a better favorable environment. In order to evaluate the performance of the reactor system, three treatment processes (CM/O3, CM alone and O3 alone) were compared to treat ROC. In the CM/O3 system, the final removal efficiency of Chemical Oxygen Demand (COD) was 81.9%, and the final removal efficiency of Total Organic Carbon (TOC) was 62.6%.