Rotating packed bed as a novel disinfection contactor for the inactivation of E. coli by ozone

The intensification of mass transfer and mixing in ozone-based disinfection processes is very important in order to achieve a certain disinfection effect at a reasonable cost. This study employed rotating packed bed (RPB), an efficient process intensification device, as an ozone-disinfection contactor, and its performance on disinfection and mass transfer was evaluated by the inactivation of Escherichia coli (E. coli) and mass transfer coefficient (k_La). The ozone exposure (Ct value) and the log inactivation of E. coli in the RPB reached 0.0008-0.0014 min mg L^-1 and 6.8-7.3 in phosphate buffered saline buffer, respectively. And the k_La in RPB rose from 0.030 to 0.186 s^-1 with the increase of liquid flow rate from 10 to 60 L h^-1. The increase of rotation speed of the RPB enhanced the log inactivation and k_La simultaneously. It was also noted that a higher gaseous ozone concentration at the identical applied ozone dosage is favorable for the inactivation of E. coli. The calculation of Hatta number indicated that the inactivation of E. coli in RPB is a diffusion-controlled process for which RPB is well suited. Compared to the conventional bubble reactor, the achievement of high disinfection efficacy at a low Ct value in RPB revealed that RPB is an efficient ozone disinfection contactor for the inactivation of microorganisms in water.