Monitoring of dry anaerobic fermentation in experimental facility with use of biofilm reactor

SINKORA, M., HAVLICEK, M.: Monitoring of dry anaerobic fermentation in experimental facility with use of biofi lm reactor. Acta univ. agric. et silvic. Mendel. Brun., 2011, LIX, No. 6, pp. 343–354 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 off ers 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, o en 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 fi h. “Percolate strategy” is another phrase used for sustaining the anaerobic fermentation; material is sprinkled on the percolate in the precisely defi ned 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 socalled biofi lm reactor. An external reactor with a cultivated bacterial biofi lm on an immovable carrier with the percolate fl owing 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 infl uences the process of anaerobic fermentation. biogas, dry anaerobic fermentation, percolate strategy, farm waste, fermentation residue, biofi lm reactor Biologically degradable waste represents a considerable part of all waste being created in households as well as within industry. The terms biomethanization, anaerobic fermentation or anaerobic digestion have been encountered with increasing frequency within the specialized literature in connection with sustainable sources of energy. 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 hermetically sealed environment. A wide range of aerobic microorganisms participate in the process at the beginning. Then comes the anaerobe facultative and lastly the bacteria strictly necessitating the absence of oxygen. These produce methane which is one of the two 344 M. Sinkora, M. Havlicek basic elements of biogas. Even the smallest amount of oxygen present results in their perishing and the whole process of anaerobic stabilisation comes to an end (STRAKA, 2006). 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% (25% and even more as presented in diff erent sources), is a frequently discussed topic nowadays. It is 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. The problem of draining the digestive has been frequently discussed in the fi eld of raw materials and biological waste processing (in the branch of liquid anaerobic fermentation). Thus, it is more than possible that dry fermentation, capable of processing the material with a dry matter percentage of up to 60%, will become more competitive with “traditional biogas plants”. The issue of processing biodegradable waste by the method of dry fermentation may be denoted as very rarely spread within the Czech Republic and Slovakia. There are only two facilities in operation within the whole of the Czech Republic. The founders of the idea of dry fermentation are the German companies Bekon and Bioferm. Companies which use the system with continual operation are Dranco (Belgium), Kompogas (Switzerland), Anacom (Switzerland), and Valorga (France). These technologies are suitable for the mechanicalbiological adjustment of communal waste and are suitable for use within the community sphere (BRKO). With regard to the world wide situation, where the increase in the proportion of the energy from sustainable sources is demanded, anaerobic fermentation off ers a possibility of transforming farm waste, farm products, municipality waste of biological character into electricity. This electricity may subsequently become an interesting source of income for various subjects. The off er may be proposed to agricultural companies as well as to municipality corporations. Two years ago, the technologies producing “renewable energy”, especially the photovoltaic technology, which has so o en become a victim of fi nancial speculation, experienced a start with a rocket speed. Nowadays, a more cool-headed approach to the division of the sources of energy has been taken. This gives a big chance for biomass processing to stand out from other sources. The “photovoltaic boom” has created a media portrayal which has thrown other technologies and sustainable sources of energy into the shade. Nonetheless, new, promising technologies have come into existence and there is still a lot to explore, research and develop. The aim of this paper is to analyze the conduct of biological materials processed via dry fermentation in laboratory conditions and in the experimental facility; then to compare the biogas yield with the standard values. The methane biofi lm reactor has been found to increase the biogas yield; this reactor has been inserted between the substrate reactor and percolate tank. The process of mechanization running for 26 to 33 days has been depicted in the graphs. A partial aim of this paper is to assign and asses the percolate strategy by means of statistical dependence. The aim is to describe the infl uence of the percolate amount and the number of the percolate cycles on the volume of the produced biogas. The reduction potential and pH are other benchmark values.