Abstract

The object of research is the process of water disinfection at the influence of gas from bacteria of a particular genus with different amounts per unit volume of water. Due to the annual increase in the amount of pollutants in natural waters, new opportunities to improve microbiological indicators of water quality are being explored. There are many different ways to disinfect it, both physical and chemical. However, no single method has been found to purify aqueous media from microorganisms that would ensure their effective destruction. It is proposed to study the activity of specific microorganisms during the bubbling of inert gas through the aqueous medium. The microorganisms studied were rod-shaped sporogenic cells of Bacillus cereus bacteria type. The test gas was inert helium. The study used continuous gas bubbling throughout the process, which allowed to mix microbial water efficiently and prevent the formation of stagnant zones in the reaction medium. In particular, active gas mixing facilitates its access to each cell. The gas supply rate corresponded to 0.2 cm3/s, and its flow rate was 0.7 dm3 for one hour of bubbling through microbial water. The duration of the entire research process was 7200 s. The constant temperature of the microbial water (T=288±1 K) was maintained during the experiment by cooling the glass reactor with running water. An in-depth method of culturing bacterial cells was used. A decrease in the number of microorganisms was observed throughout the helium supply process, despite the different initial amounts in the water. The highest destruction degree of bacillus (77.06 %) was obtained at the lowest studied concentration in water (NM01=3.4·104 CFU/cm3). This is due to the fact that less microbial load provides better conditions for access of helium to the cell and their effective destruction. The proposed method of water purification allowed to achieve a sufficiently high degree of water disinfection from sporogenic rod-shaped bacteria after the action of helium alone. In particular, it has been experimentally proven that the efficiency of the water disinfection process depends on the concentration of microorganisms per unit volume of water. Due to the treatment of contaminated water with gas, it is possible to obtain high rates of its purification and the application of this method for practical purposes in water treatment technology.

Highlights

  • The processes of water purification from various micro­ organisms are still being studied by scientists, because water contains pollutants of chemical and biological pollutants [1,2,3]

  • It is important to study the viability of microorganisms under the influence of helium, the action of which has not been studied in the processes of water disinfection

  • The aim of research is to study the change of microorganisms number in the aqueous medium in the helium atmosphere

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Summary

Introduction

The processes of water purification from various micro­ organisms are still being studied by scientists, because water contains pollutants of chemical and biological pollutants [1,2,3]. The oxygen effect on aerobic bacteria was studied in [11], where studies have identified and described the processes of accumulation and reduction of microbial counts in the water. At low concentrations of Bacillus bacteria, their active reproduction in an oxygen atmosphere was studied, and at high concentrations, a decrease in the number of cells in water was observed [11]. The influence of hydrogen, argon, oxygen, air and low-intensity ultrasound on the viability of Saccharomyces cerevisiae yeast is described in [12]. It is important to study the viability of microorganisms under the influence of helium, the action of which has not been studied in the processes of water disinfection. The aim of research is to study the change of microorganisms number in the aqueous medium in the helium atmosphere

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