Anaerobic co-digestion of sewage sludge and food waste for hydrogen and VFA production with microbial community analysis

In this study, the anaerobic co-digestion of food waste (FW) and sewage sludge (SS) was investigated for the production of hydrogen and volatile fatty acids (VFAs). The results showed that the anaerobic co-digestion of these materials enhanced the hydrogen content by 62.4% (v/v), 29.89% higher than that obtained by FW digestion alone, and the total VFA production reached at 281.84 mg/g volatile solid (VS), a 8.38% increase. This enhancement was primarily resulted from improvements in the multi substrate characteristics, which were obtained by supplying a higher soluble chemical oxygen demand (23.78-32.14 g/L) and suitable a pH (6.12-6.51), decreasing total ammonia nitrogen by 18.67% and ensuring a proper carbon/nitrogen ratio (15.01-23.01). Furthermore, maximal hydrogen (62.39 mL/g VS) and total VFA production potential (294.63 mg/g VS) were estimated using response surface methodology optimization, which yielded FW percentages of 85.17% and 79.87%, respectively. Based on a pyrosequencing analysis, the dominant bacteria associated with VFA and hydrogen production were promoted under optimized condition, including members of genera Veillonella and Clostridium and the orders Bacteroidales and Lactobacillales. (C) 2018 Elsevier Ltd. All rights reserved.