Find in Library

Anaerobic fermentation is a process in which almost any organic mass may be transformed into an energetically rich biogas and a fermentation residue. Only strictly anaerobic microorganisms enter into the process; thus the process may take place only in a hermetically sealed environment. With regard to the world wide situation, where the increase in the proportion of energy from sustainable sources is in demand, anaerobic fermentation offers the possibility of transforming farm waste, farm products and municipality waste of biological character into electricity. This electricity may subsequently become an interesting source of income. The system may be proposed to agricultural companies as well as to municipality corporations. The process of fermentation may be carried out as dry fermentation or as liquid fermentation. Dry fermentation, working with materials where the percentage of dry matter exceeds 15 %, is the topic of this paper. This method has been frequently discussed as a method of processing organic material without waste water and thus the volume of material as well as the size of the biogas plant considerably decreases. To enable progress in the process, it is necessary to use a biologically active liquid solution containing the essential micro-organisms, often termed “percolate”. To activate a fresh substrate, fermented material adulterant containing cultivated microorganisms from previous processes is used; the ratio in which it is used is approximately one third to one fifth. “Percolate strategy” is another phrase used for sustaining the anaerobic fermentation; material is sprinkled on the percolate in the precisely defined cycles. In addition, the biologically active liquid solution contains organic substances washed out from the fermented material. With regard to its amount, this paper has become an impulse for the research in the amount of biogas which may be subsequently produced from the percolate in the so-called biofilm reactor. An external reactor with a cultivated bacterial biofilm on an immovable carrier with the percolate flowing through it has been constructed in laboratory conditions for this purpose. The choice of suitable percolate strategy (this means the frequency of sprinkling) and the amount of percolate directly influences the process of anaerobic fermentation.