Periodic Reporting for period 2 - DEMETER (Demonstrating more efficient enzyme production to increase biogas yields)
Période du rapport: 2018-02-01 au 2020-01-31
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.
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.
During 42 months of DEMETER activities, many results were achieved. An improved fermentation process for enzyme production at lab-scale was developed and scaled-up to industrial scale. The improved fermentation process showed an improved yield in 150L, 1.500L and 15 m3 scale fermenters: 60% more protein has been produced. The downstream process for enzymes purification has been optimized: the recovery has been improved with 50%.
Laboratory tests in batch and semi-continuous scale for wet and dry biogas fermentation processes have been performed. All together eight semi-continuous biogas tests with a substrate mixture of straw plus cow manure and rye-silage in combination cow manure have been operated. The effect of the enzyme addition has been very limited. A dry biogas process has been tested on different types of organic waste materials. For each substrate, 4 reactors have been run: 2 without enzyme and 2 with enzyme addition. Also here, only a small effect of the enzyme has been observed in the digesters (2-8% more biogas produced and a higher process stability). No effect of the enzyme on the total solids and/or volatile solids content was observed. Nine biogas plants, representing very different technical concepts and each designed for a specific range of input materials, were involved in the full-scale trials. As the majority of the plants is operated under commercial aspects, trial runs were superimposed by a number of factors which influenced the final result and made them difficult to interpret. Results show differences between wet and dry fermentation systems: effects on substrate degradation efficiency are higher at dry fermentation systems. The full-scale trials at waste processing plants showed quite non-uniform results. There was no scientific provable effect of enzyme application found, but subjective observations of plant operators revealed a distinct positive influence of enzyme application regarding to an improved flow behavior of digestate. For the trials at agricultural plants, a small positive effect of enzyme application on substrate degradation efficiency was observed, however out of statistical evidence. A clearly positive effect was shown on rheology behavior. Next to that, a felt improved flow behavior of digestate and a better overall digestate quality was reported by the majority of plant operators.
Based on the data gathered during the project period, a techno-economic evaluation and an LCA analysis have been performed. A business strategy for the DEMETER commercially-exploitable assets has been developed based on the above-mentioned results in combination with the market analysis that has been done. A dissemination plan was made at the start of the project and was executed accordingly.
Laboratory tests in batch and semi-continuous scale for wet and dry biogas fermentation processes have been performed. All together eight semi-continuous biogas tests with a substrate mixture of straw plus cow manure and rye-silage in combination cow manure have been operated. The effect of the enzyme addition has been very limited. A dry biogas process has been tested on different types of organic waste materials. For each substrate, 4 reactors have been run: 2 without enzyme and 2 with enzyme addition. Also here, only a small effect of the enzyme has been observed in the digesters (2-8% more biogas produced and a higher process stability). No effect of the enzyme on the total solids and/or volatile solids content was observed. Nine biogas plants, representing very different technical concepts and each designed for a specific range of input materials, were involved in the full-scale trials. As the majority of the plants is operated under commercial aspects, trial runs were superimposed by a number of factors which influenced the final result and made them difficult to interpret. Results show differences between wet and dry fermentation systems: effects on substrate degradation efficiency are higher at dry fermentation systems. The full-scale trials at waste processing plants showed quite non-uniform results. There was no scientific provable effect of enzyme application found, but subjective observations of plant operators revealed a distinct positive influence of enzyme application regarding to an improved flow behavior of digestate. For the trials at agricultural plants, a small positive effect of enzyme application on substrate degradation efficiency was observed, however out of statistical evidence. A clearly positive effect was shown on rheology behavior. Next to that, a felt improved flow behavior of digestate and a better overall digestate quality was reported by the majority of plant operators.
Based on the data gathered during the project period, a techno-economic evaluation and an LCA analysis have been performed. A business strategy for the DEMETER commercially-exploitable assets has been developed based on the above-mentioned results in combination with the market analysis that has been done. A dissemination plan was made at the start of the project and was executed accordingly.
DEMETER has brought innovation to both the fermentation process used for production of the enzyme, and to the use of enzyme-enhanced fermentation in production of biogas. The C1 platform is an industrial platform to produce specific fungal enzymes to a very high titer and purity. The development of the fermentation process for the C1 enzyme has been approached by analyzing the intracellular pathways of the production organism during the production of enzymes, which has resulted in the identification of nutrient limitations during fermentation that hamper production. All results obtained so far have been used to develop a mathematical model for the fermentation. This model has been used to further optimize the fermentation process. The optimized fermentation protocol has been tested on pilot and industrial scale and clearly showed improved yields, as well as the optimized downstream processing process. In DEMETER the effect of the C1 enzyme on the biogas process has been tested and used to develop a numerical model. Lab scale trials and nine field trials have been used to collect the data. This way, a model-based assessment of an individual biogas plant can be made, and the expected effect of the enzyme can be quantified in advance. This not only increases the specific effect of the enzymes, but also increases the economic impact. Next to this, a pipe viscosity meter has been developed to measure the viscosity of digestate. Which resulted in clear viscosity data that showed that the enzyme had a reducing effect on the viscosity.