*Escherichia coli* **Inactivation Using Pressurized Carbon Dioxide as an Innovative Method for Water Disinfection**

Tsuyoshi Imai and Thanh-Loc Thi Dang

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.68310

### **Abstract**

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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 CO<sup>2</sup> could be a potentially useful disinfection method for water treatment.

**Keywords:** bactericidal performance, *Escherichia coli*, inactivation effect, pressurized carbon dioxide, water disinfection
