STUDYING THE METHANOGENIC ABILITY OF A MICROORGANISMS CONSORTIUM IN ARTIFICIAL MINERAL MEDIA WITH DIFFERENT CARBON SOURCES
In the search for future energy sources, the benefits of biological conversion methods are considered. In laboratory setting, we have studied the dynamics of forming methane, carbon dioxide, hydrogen, and liquid metabolism products by an artificially created consortium of microorganisms in the process of the methane fermentation of synthetic substrates. Initial substrates were methyl alcohol, glucose, and acetic acid (acetate). The microorganisms were isolated and defined to their species from natural sources. Data obtained from studying the growth and methanogenesis of the microorganisms consortium on methanol shows that, along with methane, acetate and carbon dioxide are formed within the system. Moreover, the release of certain amounts of hydrogen is observed at early stages, which is quickly consumed. We have studied the dependency of the rate of releasing methane, carbon dioxide, and hydrogen on the concentration of the hydrogen ions within the medium, i.e., on pH of the medium. In the studies performed, we have found that the region of the pH values optimal for methanogenesis is within the range of 6.5-7.5. The (artificially obtained) association of microorganisms forms biogas from methanol, glucose, and acetate. It is found that acetate is the most preferable methanogenesis substrate for the consortium under research. The acetate contents in the initial substrate and at the end of methane fermentation were found using the Lurie-Rybnikova method. Methane is shown to be formed from acetate in equimolar amounts. In methane fermentation, a biogas is formed that consists of methane (up to 80%), carbon dioxide (15-20%), and small amounts of water vapor, sulfureted hydrogen, oxygen, ammonia, hydrogen, and nitrogen oxides. The composition of the forming biogas in dynamics was identified using gas chromatography. As a result of cleaning the biogas from CO2, biomethane is obtained, i.e., a key energy source. The biogas can also be used in heat production. To evaluate the biogas quality, yield, and amounts, we find it reasonable to relate everything to methane with its specified parameters. Organic substances used in obtaining the biogas are basically the wastes of various industries, such as livestock farming, poultry farming, agriculture, etc.