Increasing the methane production rate of hydrogenotrophic methanogens using biochar as a biocarrier

The existence of CO₂ in biogas will affect its practicality, so the methanation of CO₂ is of great significance. Carrier materials play a key role in bioconversion of CO₂ to methane during biogas upgrading. Herein, different materials were used to evaluate the bioconversion process of CO₂ to methane, which consisted of black ceramsite (BC) and biochars prepared from corn straw and digestate. The results showed that after adding the carrier materials, the methane production rate increased by more than 20%, and the corn straw biochar (CSB) group even increased by more than 70%. This may be attributed to the large specific surface area and more functional groups in corn straw biochar which was suitable for the immobilization of hydrogenotrophic methanogens (HMs). Therefore, corn straw biochar is a good carrier material for the accelerated bioconversion of CO₂ to methane.