Theoretical Background and Objectives
Biochar can have a range of positive effects on anaerobic digestion. Due to its high specific surface area, it provides ample surface area for microbial growth, potentially leading to more efficient methane production. Additionally, its ability to adsorb contaminants can enhance the process stability of anaerobic digestion [1].
One method for producing biochar is vapothermal carbonization (VTC), where biomass is heated under pressure with saturated steam at temperatures of around 180–250°C. This process drives off some volatile substances from the biomass, thereby increasing the carbon content in the remaining solid material. Compared to other methods like hydrothermal carbonization (carbonization in hot water under pressure), VTC can achieve higher solid recovery rates, and the resulting biochar can have rougher surface structures and higher porosity [2]. So far, the use of VTC biochar in anaerobic digestion has been scarcely studied.
This master's thesis aims to investigate the extent to which biochar produced from reed stalks—a byproduct of constructed wetlands—via the VTC process is suitable for stabilizing the anaerobic digestion process. In particular, it will be examined whether the addition of ground VTC biochar can prevent acidification during digestion in batch experiments with high acetate addition. If successful, this could serve as a starting point for further investigations on a continuous scale—successful implementation of such a process could potentially lead to significantly higher organic loading rates in biogas plants in the future.
[1] Zhao, W. et al. (2021), A review of biochar in anaerobic digestion to improve biogas production: Performances, mechanisms and economic assessments, Bioresource Technology 341, 125797
[2] Yan, M. et al. (2024), Innovative carbonization techniques for food waste: A comparative study of hydrothermal carbonization (HTC) and vapor-thermal carbonization (VTC), Journal of Analytical and Applied Pyrolysis 182, 106685
Tasks
Part 1: Literature Review
- Search for relevant scientific articles
- Critical analysis of the literature
Part 2: Laboratory Work
Biochar Production
- Production of biochar using the VTC process
- Investigation of the physical and chemical properties of VTC biochar and selection of the most promising carbonization conditions for use in anaerobic digestion (based on porosity and buffering capacity)
Anaerobic Digestion
- Conducting batch tests for anaerobic digestion according to VDI 4630
- Accompanying analytics (including fatty acid analysis, determination of FOS/TAC value, measurement of methane content in biogas)
Laboratory Organization
- Proper storage and disposal of samples
- Ensuring and adhering to safety and hygiene regulations
Part 3: Data Interpretation and Preparation
- Regular data processing and consultation with the supervisor
- Comparison of results with literature data
- Analysis of experimental data using statistical methods
If you are interested, please send your application with CV and references to:
Marvin Scherzinger
Building N Room 1019
E-Mail: marvin.scherzinger@tuhh.de
Tel.: +49 40 42878 4829
