The effect of sonication on microbial disinfection using hypochlorite

Area of Science:

• Microbiology
• Acoustics
• Biocidal Efficacy

Background:

• Low-power ultrasound can enhance biocide effectiveness.
• Sodium hypochlorite is a common biocide.
• Escherichia coli is a target bacterium.

Purpose of the Study:

• To investigate the impact of ultrasonic treatment timing on sodium hypochlorite's biocidal efficiency.
• To explore frequency-dependent effects of ultrasound (20 kHz vs. 850 kHz).

Main Methods:

• Exposure of Escherichia coli suspensions to sodium hypochlorite.
• Application of ultrasound at 20 kHz and 850 kHz at different timings relative to biocide addition.
• Assessment of bacterial kill rates.

Main Results:

• A frequency-dependent effect of ultrasound timing was observed.
• At 20 kHz, simultaneous ultrasound and biocide application yielded the greatest improvement.
• At 850 kHz, pre-treatment with ultrasound immediately followed by biocide addition was most effective.
• Similar kill rates were achieved with 850 kHz pre-treatment and 20 kHz simultaneous treatment.
• 850 kHz pre-treatment required less acoustic energy, indicating higher efficiency.

Conclusions:

• Ultrasound significantly enhances the biocidal efficacy of sodium hypochlorite.
• Optimal timing of ultrasonic application is frequency-dependent.
• 850 kHz ultrasound as a pre-treatment is a more energy-efficient method for enhancing sodium hypochlorite's bactericidal activity against Escherichia coli.