Innovative brackish water treatment using ultrasound-reduced microbubbles and hydrogen peroxide

Abstract

This study investigated an innovative method combining microbubbles (MBs), ultrasound, and hydrogen peroxide (H2O2) to enhance both oxidation–reduction potential (ORP) and dissolved oxygen (DO) and disinfect Vibrio alginolyticus in brackish water. Ultrasound reduced the size of MBs and increased the saturation of DO and ORP, particularly under high-salinity conditions. This synergistic approach not only elevated ORP and DO levels but also significantly improved disinfection efficiency, showing positive correlations with flow rates (p < 0.001). Under the initial conditions of 105 ̶ 106-CFU mL⁻1 bacterial density and 20 ‰ salinity, using ultrasound (28 kHz, 100 W), H2O2 (0.9 mg L⁻1), and MBs (airflow rate of 2.0 L min⁻1) achieved a 5.3-log inactivation of V. alginolyticus in only 45 min, with a synergistic inactivation value of 4.1-log. In contrast, individual treatments with ultrasound and H2O2 resulted in only 0.6 and 1.7 log reductions after 60 min, respectively. Higher flow rates further enhanced the bactericidal effectiveness, achieving the lowest D-value of 8.76 min. These findings highlight the significant potential of this approach for brackish water treatment, as it can improve water quality while minimizing environmental impacts.

Keywords

• Oxidation–reduction potential
• Ultrasound
• H2O2
• Microbubbles
• Disinfection, water treatment