Processes for metal-to-char encapsulation

The research project deals with the conversion of biomass from plants to biochar. Thereby heavy metals which were taken up from the soil by the plants and are therefore contained in the plant parts shall be transferred to the biochar. The biochar will finally be subjected to treatment in order to reduce the reactivity, which is the tendency of biochar and heavy metals to react with other chemical compounds. This so-called encapsulation allows for a storage of the final product in underground repositories, that is safe from environmental impacts Thus, two important environmental issues can be addressed at once. First, soils with a locally high concentration of heavy metals can be purified. This contamination with heavy metals might be due to historical exploitation of these metals nearby. In their polluted state, these grounds are not suitable for agriculture, but they can be decontaminated through the cultivation of plants, that take up the heavy metals along with nutrients. In order to avoid further pollution of the environment it has to be made sure that with the disposal of the plants after harvesting no heavy metals end up in the environment anew. For that purpose, biomass is to be converted to biochar which should still contain most of the heavy metals and the chars is then prepared for long-term underground storage through subsequent encapsulation. This leads to the second big impact, which is carbon capture and sequestration or CCS. CCS is a broad term for techniques, that take CO2 out of the atmosphere and store it underground. This leads to a net negative CO2 -balance, which is an important step towards fighting climate change. The CO2 , which is consumed by the plants via photosynthesis, is not released to the atmosphere, but kept in solid state in the biochar. Thereby the long-term storage of the biochar combines heavy metal and carbon reduction above ground. Hence this project will also contribute to the fight against the climate change.