Batch anaerobic co-digestion of proteins and carbohydrates

Batch anaerobic studies were conducted using five mixtures (M1-M5) of bovine serum albumin (BSA) and starch. The results showed that co-digestion of BSA and starch had a positive impact on the methane production. The highest methane production of 288 mL, the highest methane yield of 360 mL CH4/g CODadded, and the highest maximum methane production rate of 62 mL CH4/d were achieved for M4 (20% BSA and 80% starch). Most of the particulate proteins (90%) as well as particulate carbohydrates (95%) were degraded in the first 3 days. The hydrolysis coefficients of particulate proteins and particulate carbohydrates ranged from 0.65 to 1.01 d(-1) and from 0.53 to 1.06 d(-1), respectively. The highest methane production was achieved at C:N ratio of 12.8 for M4. For BSA only, propionic acid was the main volatile fatty acid (VFA), while for the starch only, butyric acid was the predominant VFA. (C) 2012 Elsevier Ltd. All rights reserved.