<i>Escherichia coli</i> Inactivation Using Pressurized Carbon Dioxide as an Innovative Method for Water Disinfection

Abstract

Advanced water disinfection technologies that do not produce harmful by-products would be highly desirable. This study presents results for the use of pressurized carbon dioxide (CO 2) and a liquid-film-forming apparatus for disinfection of seawater. The sensitivity of Escherichia coli to the pressurized CO 2 was examined for various conditions of pressure, temperature, working volume ratios (WVRs), flow rates, and pressure cycling. Morphology of E. coli was observed by using scanning electron microscopy (SEM). A strong correlation between the E. coli inactivation efficiency and pressure cycling was detected (p < 0.001). The frequency and magnitude of pressure cycling were the key factors responsible for high rates of E. coli inactivation during the pressurized CO 2 treatment. The results from linear regression analyses suggest that the model can explain about 91% of the E. coli inactivation efficiency (p < 0.001). The pressurized CO 2 treatment (at 0.7 MPa, 20°C, 50% WVR) in the process involving pressure cycling (∆P = 0.12 MPa, 15 cycles) resulted in complete inactivation (5.2 log reduction) of E. coli within 3 min. These findings suggest that pressurized CO 2 could be a potentially useful disinfection method for water treatment.