The project consistently surpassed the current state of the art (SOTA) across its individual technological steps. The first major outcome was in CO2 conversion to C1-Building Blocks, primarily formic acid (FA). A chemo-enzymatic CO2 purification process achieved over 95% CO2 purity from real industrial off-gases, with a 25% energy cost reduction for solvent regeneration. The electrochemical CO2 reduction for FA production demonstrated robust lab-scale performance, reaching 0.77 g/(L·h) with high efficiencies (85% coulombic, 41% carbon conversion). Crucially, the FA production process showed scalability (up to 400 cm2 electrodes) and exceptional long-term stability, operating for over 4000 hours with high Faradaic efficiency, advancing this technology to TRL 5.
The second key outcome focused on bioelectrochemical nutrient recovery from industrial wastewater. Ammonia recovery rates significantly exceeded targets, reaching up to 175 g N/m2/d. The energy demand was remarkably low at 1.5 kWh/kg N, alongside efficient hydrogen (H2) production. Recovered nutrients were successfully validated as microbial feedstock for fermentation processes, moving this component to TRL 5.
Thirdly, in yeast-based fermentation for organic acids, engineered P. pastoris strains achieved impressive titers, with SA and IA surpassing 100 g/L, and high theoretical yields (97% for SA, 77% for IA). A significant breakthrough was the successful single-reactor integration of CO2 reduction, fermentation, and IA production, simplifying the process and advancing it to TRL 5.
Fourth, novel downstream processing validated high purities for all four organic acids (LA >90%, SA >96%, IA >97%, 3-HP >96%). Bio-succinic acid was successfully used for biodegradable bioplastics, and bio-lactic acid for livestock growth, demonstrating real-world applicability and reaching TRL 5.
A comprehensive sustainability assessment provided robust data confirming the positive environmental, economic, and social balance of VIVALDI solutions, identifying exploitable products and technologies. This multi-faceted assessment identified two out of five organic acids and bioelectrochemical system technologies as economically exploitable with payback periods under 20 years, with FA profitability sensitive to electricity prices. The project also assessed socio-economic impacts across five case study locations.
Proactive engagement with stakeholders, including two innovation workshops and bilateral meetings with innovation/investment companies, fostered market feedback and collaboration. The project also identified regulatory barriers and contributed to shaping supportive policy frameworks for carbon capture and utilization technologies. Synergies were created with six other Horizon 2020 projects on decarbonization.
Finally, VIVALDI partners made extensive communication and dissemination efforts, completing all planned activities by M48. This included collaborations with other Horizon 2020 projects, 3 thematic workshops, 4 training sessions/webinars, 71 participations in scientific conferences/workshops, 26 publications in peer-reviewed scientific journals, 10 news releases, and 8 bilateral meetings with stakeholders.
