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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #410006
Research Project: Innovative Manure Treatment Technologies and Enhanced Soil Health for Agricultural Systems of the Southeastern Coastal Plain

Location: Coastal Plain Soil, Water and Plant Conservation Research

Title: Maximizing the value of liquid product and minimizing carbon loss in hydrothermal processing: an evolution from carbonization to humification

Author
item MARZBAN, NADER - Leibniz Institute
item LIBRA, JUDY - Leibniz Institute
item ROTTER, VERA - Technical University Of Berlin
item HOFFMANN, THOMAS - Leibniz Institute
item HERRMANN, CHRISTIANE - Leibniz Institute
item Ro, Kyoung
item FLORNENKO, SVITLANA - Max Planck Institute Of Colloids And Interfaces
item ANTONIETTI, MARKUS - Max Planck Institute Of Colloids And Interfaces

Submitted to: Biochar
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Hydrothermal carbonization (HTC) has been used to convert the low-value wet biomass wastes into value-added carbonaceous solid called hydrochar without drying the wet feedstock. In this research, we investigated the products from hydrothermally treating cow manure digestate in alkaline condition. Because the main organic chemicals from this process are humic acids, this process is called hydrothermal humification (HTH). We found that the HTH yielded 37.4% artificial humic acids (A-HA) from both solid and liquid products, which are about twice that of HTC. The HTH reduced aromatic compounds by more than 70% in solids and 90% in liquid while significantly increasing organic acids and sugars. As a result, anaerobic digestion of HTH liquid would yield much higher biomethane than from raw digestate or HTC liquid. The HTH is a potentially promising technology in converting wet biomass waste into humic acid rich products and bioenergy production.

Technical Abstract: Hydrothermal carbonization (HTC) converts wet biomass into hydrochar and a process liquid, but aromatic compounds has been reported as inhibitor for germination, plant growth, and soil microbial activity. We compared HTC and hydrothermal humification (HTH) of cow manure digestate with increased initial alkaline content. HTH yielded 37.4% artificial humic acids (A-HAs) from both solid and liquid, twice that of HTC. HTH reduced aromatic compounds by over 70% in solids and 90% in liquids. The HTH liquid had 60% more total organic carbon (TOC) than HTC. Although one-third of TOC can be recovered as humic acid, a high TOC concentration remains in the liquid, mainly as organic acids. A-HAs in HTH resemble natural humic acids. We evaluated the effect of HTC and HTH liquid on anaerobic biomethane production and found that HTH liquid increased methane production by 46% compared to fresh cow manure, while HTC showed only 21% increase. Compared to feedstock itself, digestate cow manure (18%), the HTH significantly increased the methane yield, while HTC liquid produced only a 3% increase. The reduction of acetic acid and COD in HTH liquid indicates the potential for converting byproducts into methane during biogas production, preventing its release into the soil while maintaining humic acid levels.