In-situ biogas upgrading during anaerobic digestion of food waste amended with walnut shell biochar at bench scale.

A modified version of an in-situ CO removal process was applied during anaerobic digestion of food waste with two types of walnut shell biochar at bench scale under batch operating mode. Compared with the coarse walnut shell biochar, the fine walnut shell biochar has a higher ash content (43 vs. 36 wt%) and higher concentrations of calcium (31 vs.