EUBCE 2026 - Gabriel DE FREITAS BATISTA - Soil Responses to Hydrothermal Liquefaction Hydrochar Application: Greenhouse Gas Emissions and Earthworm Avoidance

Soil Responses to Hydrothermal Liquefaction Hydrochar Application: Greenhouse Gas Emissions and Earthworm Avoidance

Short Introductive summary

Hydrothermal liquefaction (HTL) converts wet biomass into biocrude and a nutrient- and carbon-rich solid by-product, HTL-Char. This material offers potential for carbon capture and nutrient loop closure through soil application, yet its effects on soil systems remain largely unknown. This study investigates the influence of HTL-Char on (i) greenhouse gas (GHG) fluxes, to assess its carbon storage potential, and (ii) earthworm behavior, as an indicator of ecotoxicity. HTL-Char was produced from cattle manure and straw in a continuous HTL pilot plant at Aarhus University and further treated by pyrolysis (400°C, 600°C) or water washing. Both untreated and treated chars were applied (1 and 3 wt.%) to a southern German soil and incubated for 80 days to monitor GHG fluxes. The GHG emission experiment is still ongoing. A 21-day earthworm avoidance test (1 wt.%) revealed no avoidance behavior (47–59%), indicating no ecotoxic effects. Pyrolyzed HTL-Char showed the lowest avoidance. These results suggest HTL-Char’s potential for safe agricultural use, carbon sequestration, and nutrient recycling, with pyrolysis enhancing its suitability.

G.F. Batista, University of Hohenheim, Stuttgart, GERMANY
A. Kruse, University of Hohenheim, Stuttgart, GERMANY
S. Marhan, University of Hohenheim, Stuttgart, GERMANY
G. Becker, University of Hohenheim, Stuttgart, GERMANY