Combination of Hydrothermal Carbonization (HTC) and Biogas Production

Laufzeit


Biogas production by anaerobic digestion (AD) has attracted growing interest all over the world. However, how to store and make use of the resulting digestates is still problematic. Digestates from livestock manure usually contain animal pathogens, which can increase the health risks when these digestates are applied for fertilizer without sterilization. In addition, transportation cost and seasonal demand of digestates add to the disposal difficulty.

Since the incomplete conversion of lignocellulosic feedstocks and high water content of resulting digestates from anaerobic digestion, hydrothermal carbonization (HTC) has been particularly suitable for processing of the digestates. Hydrothermal carbonization is defined as a thermochemical transformation process for low value wet biomass to a solid product termed as hydrochar. Hydrochar has been reported as a coal-like powder which has the potential for soil amendment and energetic use.

In this project, the resulting digestates will be hydrothermal carbonized into carbon-rich and stable lignite-like hydrochar by various conditions and catalysts. The hydrochar addition during anaerobic digestion and the anaerobic digestion of process water have been investigated by previous researches; however, it is not clear about the degradation of the phytotoxic compounds of fresh hydrochar and process water during anaerobic digestion. Therefore, the effect of integration of hydrochar and process water in anaerobic digestion is also interesting to understand. Further applications of hydrochar and process water involve soil amendment, activated carbon, and nutrient recovery. Another goal is the identification of the economic feasibility and energy efficiency of the overall procedures under respective process conditions.

The anaerobic digestion experiments will be performed in cooperation with State Institute of Agricultural Engineering and Bioenergy at the University of Hohenheim and a part of experiments and analyses are going to be carried out in Karlsruhe Institute of Technology.