Continuous-sterilization system that uses photosemiconductor powders.

Area of Science:

• Photochemistry
• Materials Science
• Environmental Engineering

Background:

• Photochemical methods offer potential for microbial sterilization.
• Titanium dioxide (TiO2) is a known photocatalyst effective against bacteria.
• Separation of photocatalyst particles from treated water is a practical challenge.

Purpose of the Study:

• To develop and evaluate a continuous photochemical sterilization system for Escherichia coli.
• To immobilize titanium oxide (TiO2) powders onto acetylcellulose membranes for efficient separation.
• To assess the reusability and efficacy of the developed sterilization system.

Main Methods:

• Immobilization of TiO2 semiconductor powders onto acetylcellulose membranes.
• Construction of a continuous-flow reactor system incorporating the TiO2 membrane, a mercury lamp, and a pump.
• Testing the system's sterilization efficiency against Escherichia coli suspensions under varying irradiation conditions.

Main Results:

• The TiO2-immobilized membrane system demonstrated effective sterilization of Escherichia coli.
• Complete sterilization (less than 1% survival) was achieved for E. coli suspensions at 10(2) cells/ml.
• Sterilization occurred at a mean residence time of 16.0 minutes under irradiation of 1,800 microeinsteins/m2 per s.
• The system proved to be reusable over multiple cycles.

Conclusions:

• Immobilizing TiO2 on acetylcellulose membranes provides an effective method for photochemical sterilization.
• The continuous-flow system is a viable and reusable technology for water disinfection.
• This approach addresses the challenge of photocatalyst separation in practical applications.