Effect of limonene on batch anaerobic digestion of citrus peel waste

The effect of (R)-limonene (0-3000 mg L−1) on the batch anaerobic digestion of microcrystalline cellulose was also assessed. The half maximal inhibitory concentration, IC50, was 423 mg kg−1 in an initial run and 669 mg kg−1 in a second run of batch experiments. The methane course and IC50 values indicate that there are reversible inhibition and biomass activity recovery during the anaerobic digestion process, despite the non-reversible antimicrobial mechanism described in the literature for limonene to date.