Bio-electrochemically hydrogen and methane production from co-digestion of wastes

The batch study was carried out to investigate the potential of the bioelectrochemical system in solid-state anaerobic digestion for hydrogen and methane production under thermophilic conditions. The sewage sludge was co-digested with agricultural waste and food wastes for a total solids contents (>15%) in a single chamber bioelectrolysis reactor. Hydrogen production was observed in all the bioreactors including control, whereas methane production of 7.67 ml/gCOD and 6.13 +/- 0.01 ml/gCOD were observed in the bioreactors operated at 120 mV applied voltage (R-120) and control (R-CONT) respectively. Maximum hydrogen production was observed during the first 5 days of digestion, whereas methanogenesis starts after 5 days of the incubation period. The maximum hydrogen of 38.25 +/- 0.02 ml/gCOD production was observed in reactor R-80, while it was 21.9 +/- 0.03 ml/gCOD in the R-Con. The VFAs accumulations was more in bioelectrochemical digesters as compared to control. Different kinetic models, i.e. Gompertz model, Richard model, and Logistic model well elucidate the cumulative hydrogen and methane production. The best-fitted model was compared using the RMSE and NRMSE error functions. (C) 2020 Elsevier Ltd. All rights reserved.