The aim of this work is to identify the optimum process parameters of sonication, manosonication and thermosonication for deactivating E. coli ATCC 25922 in water-based suspension. The influence of ultrasonic intensity, frequency, pressure, temperature and treatment time on the efficiency of ultrasonic treatments was investigated in this study theoretically and experimentally. The theoretical part of this study involved solving the Rayleigh-Plesset equation with different parameters and evaluating their effects on the collapse pressure of a bubble with initial radius of 0.01mm. The experimental part of the work was conducted using ultrasonic horn reactor at three levels of intensities; low (17.56 W/cm2), intermediate (21.49 W/cm2) and high (24.17 W/cm2) with fixed frequency. Thermosonication and manosonication experiments were conducted at the sub-lethal temperatures of E. coli; 45, 50, 55 and 60°C and pressures of 2, 3 and 4 bars. The optimum treatment conditions of sonication, manosonication and thermosonication were evaluated through calculating the specific energy required to obtain 5 log reduction of E. coli in each treatment. Thermosonication treatment at 21.49W/cm2 and 45°C for 4 minutes was found to be the optimum treatment conditions to deactivate E. coli in water-based suspension.
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