Effect of alternative sources of input substrates on biogas production and its quality from anaerobic digestion by using wet fermentation
¹Slovak University of Agriculture in Nitra, Faculty of Engineering, Department of Machines and Production Biosystems, Tr.A. Hlinku 2, SK949 76 Nitra, Slovakia
²Slovak University of Agriculture in Nitra, Faculty of European Studies and Regional Development, Department of Regional Bioenergy, Tr.A. Hlinku 2, SK949 76 Nitra, Slovakia
*Correspondence: koloman.kristof@uniag.sk
Abstract:
The aim of the study was to confirm the suitability of alternative input substrates for production of biogas in order to decrease the need of utilization of high quality maize silage. All of the experiments were conducted by employment of wet fermentation process in mesophilic conditions (temperature in fermentor 40 ± 1 °C) in experimental fermentor with volume 5 m3. The experiments were realised in operating conditions of biogas station designed for utilization of agricultural biowaste. The experiments were divided into two alternatives (I and II cycle) and one control input substrates. In the first alternative (I cycle) was daily dosage formed by 33 kg of Amaranth and 250 L of control manure mixture. In this cycle, more than 3–times greater specific production of biogas was observed with average methane content 63.9% in comparison with control manure mixture (80 : 20%, liquid manure and manure). In the second alternative (II cycle) was daily dosage formed by 19.5 kg of sugar beer cuts, 3.3 kg of maize silage, 1.9 kg of oil-seed rape moldings, 2.5 kg of glycerin and 250 L of control manure mixture. In this cycle, more than 5.9–times greater specific production of biogas was observed. The decrease in average methane content 55.1% however also decrease in average content of hydrogen sulfide (128 ppm) was observed as well. An unquestionable advantage for both tested alternative mixed substrates was increase in biogas production and its quality in comparison with control substrate based on manure. At the basis of these findings can be concluded that both tested alternative input substrate mixtures are suitable as co–fermentation substances with great potential to increase the biogas production and its quality in case of wet fermentation processes.
Key words:
anaerobic digestion, biogas, co-fermentation, co-substrates, wet fermentation