4. Biogas valorization

Biogas from biomass anaerobic digestion units is mainly composed of methane and carbon dioxide (table 11 ). Some other gases are also formed during the biological transformation of the material: sulfur compounds (H ₂ S, mercaptans), ammonia NH ₃ , halogen compounds (F, Cl...), organo-silicon compounds (siloxanes)... The biogas produced contains water vapor at saturation but also gases from volatile molecules present in the original substrate. In certain batch processes requiring regular opening of the digesters for their feed, the biogas may also contain N ₂ nitrogen. Some of these minority gases will then have an impact...