New CIRCULAIR Publications 

New Publications

We are happy to announce the publication of three peer-reviewed papers by project partners Aarhus University (AU), Eni, Universidad Complutense de Madrid (UCM) and University of Hohenheim (UHOH).

1- Schuck, C.E., Chiaberge, S., Anastasakis K., Biller P. (2025). Exothermicity study of wet oxidation of hydrothermal liquefaction aqueous phase using high-pressure differential scanning calorimetry. Carbon Resources Conversion, 100397. https://doi.org/10.1016/j.crcon.2025.100397

This study, co-authored by AU and Eni, quantifies the heat release from wet oxidation of hydrothermal liquefaction aqueous phases and shows that the exothermic potential is governed by the composition of dissolved organic compounds in the aqueous phase. The results provide a quantitative basis for the autothermal integration of HTL and WO, enabling energy-efficient aqueous phase treatment and recovery of valuable intermediates. This directly supports CIRCULAIR’s objective of advancing circular carbon conversion through energy-integrated valorisation of biogenic process streams.

2- Martín-Gutiérrez, D., Barras, D., Suárez-Rodríguez, P., Biller, P., Schuck, C. E., Águeda Maté, V. I., Larriba, M. (2026). Solvent selection and optimisation of the liquid-liquid extraction of volatile fatty acids from the aqueous stream of the HTL-WO process for the production of aviation biofuels. Separation and Purification Technology, 390, 136923. https://doi.org/10.1016/j.seppur.2026.136923

This paper co-authored by UCM and AU, demonstrates the recovery of volatile fatty acids (VFAs) from aqueous streams generated during hydrothermal liquefaction and wet oxidation process (HTL-WO) using terpene-based green solvents. Experimental liquid–liquid extraction achieved high VFA recoveries and was successfully simulated at an industrial scale, contributing to circular integration and resource recovery within HTL processes.

3- De Freitas Batista, G., Kruse, A., Becker, G. C., (2026). Mitigating phytotoxicity of hydrothermal liquefaction hydrochar toward potential agricultural applications. Journal of Hazardous Materials Advances, 21. https://doi.org/10.1016/j.hazadv.2026.101080

HTL-hydrochar derived from a mixture of manure and straw residues was upgraded through scalable post-treatments to eliminate phytotoxicity and enable safe agricultural application. Washing and mild pyrolysis removed organic inhibitory compounds, producing modified chars that enhanced plant growth without heavy-metal uptake. These results delivered by UHOH support further agronomic testing, contributing to nutrient loop closure, soil carbon storage, and the development of a CIRCULAIR valorization pathway for a challenging HTL by-product.