Efficiency of Co-substrates Application and Thermal Processing in the Field of Methane Fermentation of the Distillers Grains

Abstract

The aim of the work is to consider the influence of thermal processing and dosing of target components in order to maintain optimal parameters of the methanation process of the distillers grains and optimal pH level. Molasses and aluminium phosphate were indicated as intentional supplements. The purpose of the additives is to increase the alkalinity buffer in terms of acidogenesis and hydrolysis. In order to achieve the aim of the study, the following methods were used: methodology according to DIN 38 414 s8 and methodological guidelines related to the determination of physical and chemical parameters of the distillery brew, target additives and inoculum. In the study the following determination was made: volume of biogas and concentrations of biogas components such as CH4, CO2, H2S, O2. The yield of biogas was compared with reference to: mixtures of distillers grains, not thermally processed and thermally processed in the presence of the indicated ingredients. The thermal method of distillers grains processing allowed to accelerate the hydrolysis process and changed the pH of the substrate only slightly. Distillers grains not thermally treated showed a biogas yield that was about 67% higher than the unprocessed distillers grains. The best results of the pH stabilization process for the distillers grains were obtained for the mixture with molasses. The biogas yield of the mixture has increased by 2.7 times in relation to the heated WDGS.