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 (CO2) and a liquid-film-forming apparatus for disinfection of seawater. The sensitivity of Escherichia coli to the pressurized CO2 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 CO2 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 CO2 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 CO2 could be a potentially useful disinfection method for water treatment.
Part of the book: Escherichia coli