SIMULTANEOUS ACTION OF CAVITATION AND INERT GASES ON THE WATER PURIFICATION FROM BACTERIAL CELLS

Abstract

The simultaneous effect of cavitation and inert gases (argon and helium) on the process of microorganisms (MO) destruction has been studied. Sporogenic rod-shaped bacteria of the Bacillus cereus type were used for the study. The initial microbial load was 104 cells per 1 cm3 of test water. The volume of water for the study was 75 cm3. The source of the cavitation phenomenon was an ultrasonic generator with a frequency of 22 kHz. The gas was bubbled through the water system at a rate of 0.2 cm3/s throughout the duration of the process (2 h) with a total flow rate of 0.7 dm3/h. After every 30 min of simultaneous action of gas/cavitation, water samples were taken to determine the dynamics of the number of microorganisms (NM) from the time of water treatment. The change in the NM for each gas is given depending on the duration of the process and the initial number of cells per unit volume of water. To compare the effectiveness of the studied gases, the values of the effective rate constant of bacterial destruction (kd) were calculated according to the kinetic equation of the first-order reaction. According to the calculated kd values, the higher efficiency of bacterial destruction during argon bubbling under cavitation conditions was noted, in comparison with helium in similar experimental conditions. It is shown that kd(Ar/US) > kd(He/US). The efficiency of the process of water purification from pollutants of biological origin under cavitation conditions depends on the nature of the bubbled gas.