THE EFFICIENCY OF THE WATER PURIFICATION PROCESS FROM BACTERIA DEPENDING ON THE GAS NATURE
Lviv Рolytechnic National University, Lviv, Ukraine
Keywords: Bacillus cereus, gas, water purification, bacteria destruction
A study of the influence of different gas nature on the efficiency of water purification from rod-shaped bacteria of the Bacillus cereus type is presented. The action of oxygen, carbon dioxide and inert argon and helium were used. The investigated water was model microbial water obtained on the basis of deaerated distilled water with the introduction of a pure culture of bacteria in the amount of 7 · 104 CFU/cm3. The total duration of the process was 2 hours at a reaction medium with temperature of 288 ± 1 K. The change in the number of microorganisms from the duration of gas bubbling is shown, depending on its nature. The degrees of destroyed microorganisms were calculated after each sampling of water (Dd), which was taken after each 30 min of the process. Studying the influence of different modes of water treatment, the largest number of destroyed bacterial cells was studied in an atmosphere of carbon dioxide (Dd = 91.0 %), and the smallest - in an atmosphere of oxygen (Dd = 34.73%). A two-stage process of number of microorganisms change was detected in the oxygen atmosphere: an increase in the first stage during 1800 s and a subsequent decrease in the second stage. After CO2 bubbling with a rate of 0.2 cm3/s through an aqueous medium with a volume of 75 cm3, the microbial count decreased by two orders of magnitude, which is apparently due to an increase in the acidity of the test medium. Having found a high efficiency of CO2 on the process of bacterial cells destruction, this gas should be used in water treatment processes, as well as in combination with other reagents or physical methods of water treatment to enhance the destructive effect on micro-objects.
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