Hydrogen production from biomass and organic waste using dark fermentation. An analysis of the effect of operating parameters on process performance in literature studies

In the context of hydrogen production from biomass or organic waste with dark fermentation, this study analysed 55 literature studies (339 experiments) looking for the effect of operating parameters on process performance. The effect of substrate concentration, pH, temperature and residence time on hydrogen yield, productivity and content in the biogas was analysed. In addition, a linear regression model was developed to also account for the effect of: nature and pre-treatment of the substrate; inhibition of methanogenesis; continuous or batch operating mode. The analysis showed that the hydrogen yield was mainly affected by pH and residence time, with the highest yields obtained for low pH and short residence time. High hydrogen productivity was favoured by high feed concentration, short residence time and low pH. More modest was the effect on the hydrogen content. The mean values of hydrogen yield, productivity and content were, respectively, 6.49 % COD COD-1, 135 mg l-1 d-1, 51 % v/v, while 10 % of the considered experiments obtained yield, productivity and content of or higher than 15.55 % COD COD-1, 305.16 mg l-1 d-1, 64 % v/v. Overall this study gives insight on how to select the optimum operating conditions to obtain the desired hydrogen production.