MODELING THE INITIAL STAGE OF GRAIN STILLAGE BIOGAS FERMENTATION IN A LABORATORY REACTOR

• Date: 2026
• Main Authors: Kulichkova , H., Ivanova , T., Samarin , V., Vovk , E., Tsygankov , S.
• Format: Article
• Language: Ukrainian
• Published: Institute of Renewable Energy National Academy of Sciences of Ukraine 2026
• Subjects: biogas; methane fermentation; stillage; waste utilization; bioethanol; microorganisms; biotechnology.
• Online Access: https://ve.org.ua/index.php/journal/article/view/616
• Journal Title: Vidnovluvana energetika

Bioethanol plants face challenges in the maintenance of using production waste, such as stillage. For every 1 liter of bioethanol, 10-15 liters of stillage are generated. It can be used as a raw material for the production of concentrated feed, or stillage, which is subjected to methane fermentation to obtain a gaseous energy carrier - biogas. In this way, this Thus, the production waste is valorized, and there is a the possibility of replacing fossil fuels in the production of bioethanol appears. The commissioning of industrial biogas reactors is associated with certain difficulties. Our task was to generate a model simulate the commissioning of a reactor start-up for biogas fermentation of stillage, which comes from an operating plant with a capacity of 170 m3 of bioethanol per day. To carry out the biogas fermentation process, a laboratory reactor with a working volume of 300 l was used, equipped with a temperature stabilization system (electric heating), an electric mixer, devices for periodic loading of the substrate and removal of the fermented liquid, a gas removal and accounting system using a meter. Methane fermentation was controlled by FOS/TAC indicators. The substrate (stillage) was taken directly from the plant, with a stable technological mode of bioethanol production throughout the experiments. The inoculum was digestate (a by-product of biogas production) collected from an operating industrial biogas plant. During the work, the composition of the raw material and inoculum was studied, and the pH and temperature of the biogas process were controlled. The methanogenesis process took place under thermophilic conditions, at 45-50 °C, the substrate load on dry matter was 4 ± 0.4 kg/m3 per day. The specific biogas yield during the experiment was 48.5±1.0 m3 per m3 of bard. The methane content in biogas during the period of stable fermentation (13…25 days) was 60.7 ± 0.8% by volume. Based on the results of the experiments, it can be concluded that the addition of lignocellulosic substrate will increase the biogas yield. Given the level of FOS/TAC, when commissioning and operating an industrial reactor for wort fermentation, the organic matter loading can be recommended to 5…6 kg/m3 per day. The data obtained will be used when commissioning reactors of an industrial biogas plant for stillage processing in an amount of 1000…1100 m3 per day.