The Basic Technologies of Mass Transfer and Their Progress in the Field of Upgrading Biogas

Biogas is a gaseous mixture which is produced by the anaerobic digestion of organic matter. Biogas cleaning and modification of the composition means a decrease in the content of CO2, an increase in CH4 and the removal of undesirable components. The ratio between CH4 and CO2 is important for energy (and economic) values. Undesirable components have a negative effect on the technological use of biogas. It is possible to produce gas with 80 – 99.9 vol. methane % by cleaning and upgrading the biogas. This gas is called biomethane in order to highlight its non-fossil origin. Basic technologies of mass transfer, such as absorption and adsorption (or a combination of these processes – applied in a membrane), are used for cleaning biogas. The basic description and progress of these processes in recent years is described in the text as well as a summary of their advantages and disadvantages.