Application of novel enzyme preparations for biogas production in practice

The effectiveness of enzyme preparations was investigated under real-life conditions in a commercially operated full-scale biogas plant, aiming to bridge the gap between promising laboratory results and the challenges of practical application. The selected biogas plant represents a typical agricultural setup, processing a feedstock mixture with high proportions of cattle slurry and manure (each up to 29% of the fresh mass input), combined with feed rye and grass silage. These components are considered difficult to degrade, which suggested a high potential for enzymatic treatment. The enzyme products used are characterized by a combination of different enzymatic activities, enabling the breakdown of both dung and straw contained in manure, as well as viscous components from grass and whole crop silages. Due to the substrate-specific nature of enzymatic activity, the selected enzyme products and the applied feedstock mixture appeared to be an excellent match. A comparison between a 14-week reference phase and a 12-week phase with enzyme application revealed a clear impact on plant performance. The specific methane yield increased by 18% during the application period, reaching an average of 346 m³ CH₄/t oDM. This resulted in an average surplus of 210 kWh of electrical energy per ton of oDM. Power self-consumption remained stable at an average of 6.7%. The observed effects confirm the suitability of the applied enzyme products and are based on an exceptionally large dataset, including daily monitoring of plant performance and weekly feedstock characterization.