Batch anaerobic co-digestion of proteins and carbohydrates

► Anaerobic codigestion of five mixtures of proteins and carbohydrates were evaluated. ► Mixing ratio of 20% protein and 80% starch was superior to all other mixtures. ► Hydrolysis constants of proteins and carbohydrates ranged from 0.53 to 1.06 d−1. ► Propionate and butyrate were the main acids of protein and starch, respectively. ► The highest methane production was achieved at C:N ratio of 12.8.