Methane

Natural resources will definitely end sometimes, and we seem to get buried under giant heaps of rubbish. Where mankind should put all these wastes? Many countries have found a nice solution for this burning problem and even get profit of it. Russia recently also started working in this direction.

Any kinds of wastes of organic origin can be degraded by means of microorganisms. When oxygen is excluded from the process, organic wastes are turned into biogas, mainly consisting of methane and carbon dioxide. Currently biogas is synthesized from wastes in so-called bioreactors. Methane from biogas (over 95%) is of technical grade and can be forwarded to gas pipelines or used for producing electric or thermal energy.

In Russia there are many landfill sites for storing solid wastes. These sites are a strong source of biogas, which can be captured by special facilities and used for abovementioned purposes.
Anaerobic fermentation, a biogas-forming process, is performed by three groups of microbes, connected by eating preferences. Each group lives on metabolites of another one. First stage of the process involves hydrolytic organisms; second – acid-producing microbes, and the third one – methane-producing organisms. Microbiologists have created many microbial consortia, which   start processing wastes almost immediately. The bioreactor is filled with organic wastes, most commonly with manure. Oxygen is expelled at the very beginning, and all a bioreactor needs is refilling from time to time.

Apart from biogas, these bioreactors are able to produce high-quality organic fertilizers, which an extremely valuable feature for farmers. Microbial fertilizers are more “nutritious”, than ordinary composts, because composting loses up to 40% of nitrogen and other essential elements to the atmosphere. Russian microbiologists have developed optimal conditions for development of mentioned microbial consortium, and now happy microorganisms are able to produce much more biogas, than their European relatives.

Another problem, successfully solved by Russian microbiologists, is creating a new efficient technique for biological methane purification. Three techniques for methane purification exist to date: chemical adsorption of unwanted contaminants, membrane separation, and cryogenic technique (freezing).  Russian researcher have combined two of them and developed a membrane-adsorption method of methane purification, which combines advantages of both employed technologies and lacks their drawbacks. Using mentioned technique with patented membranes helps avoid additional energy spending, which in traditional purification techniques are required for heating sorbing agent, for gas mixture cooling or for biogas pressure increasing.

What researchers need now, is putting their membranes into commercial production in order to make them cheaper. We need to pay more attention to microorganisms, since they can be a good help in synthesizing valuable substances or processing unwanted ones.

Source: Science & Technologies

Anna Kizilova