Nowadays, the transition from an economy dependent upon fossil resources to a sustainable bio-based economy is becoming a priority for the society. One of the most promising developments in this regard is the conversion of biomass into energy sources (biofuels, biogas), making the optimization of these conversion strategies an essential step to reach such transition. For the efficient conversion of biomass or agricultural, industrial and municipal waste into fermentable sugars, chemical building blocks or bio-based materials, enzymes play an indispensable role. However, enzymes have not been specifically developed for the biogas production so far, but enzymes efficiency is largely evaluated by trial and error. Thus far, the use of enzymes has not lived up to the expectations as little or no effects could be observed. Hence, efficient enzyme-enabled biomass conversion requires the availability of enzymes that have proven to be effective in practice and can be produced at an industrial scale. GIBV has developed a new enzyme product derived from the fungus Myceliophthora thermophila C1, that has proven to have the potential to increase biogas production by at least 10%. Although the efficacy of the enzyme has been shown, the current fermentation process does not provide sufficient yield in industrial production to be cost-effective for large-scale application. The DEMETER project aimed to optimize the fermentation process of the C1 product and demonstrate this on industrial scale. The objective of DEMETER was to increase the yield of this industrial fermentation process by at least 20%, improve the product recovery process by 40%, and reduce overall product costs by at least 15% while increasing the productivity of the process. In addition, DEMETER demonstrated the efficiency of the enzyme in nine field trials in biogas plants.
The newly developed fermentation process was successfully implemented on industrial scale, resulting in an increase of 60% in protein yield and the downstream processing was improved by 50%. The effect of enzyme addition to the anaerobic digestion was investigated in lab scale and large scale for both wet and dry fermentations. Parameters such as biogas yield, VFA production and viscosity were measured. A clear and statistically significant decrease of viscosity after enzyme application was measured. The enzyme also had a positive effect on the production of VFA in dry fermentations. The data showed that the enzyme may attribute to higher biogas yield and a more stable process. Observations of almost all plant operators revealed a positive influence of enzyme application on the flow behavior of digestate.
