Determination of suitable operating conditions for biohydrogen production from potato production medium by dark fermentation and kinetic analysis

Purpose: In this work, effects of agitation speed, inoculum ratio, initial substrate concentraion and incubation temperature were investigated for anaerobic biohydrogen production using Clostridium butyricum microorganism in potato production medium were investigated. Using the data obtained, the relationship between substrate concentration and product production was evaluated by kinetic analysis. Theory and Methods: Batch anaerobic biohydrogen production using Clostridium butyricum NRRL B-1024 microorganism in potato production medium was investigated. The effect of inoculum ratio was examined at 1:10, 1:50, 1: 100 and 1: 200 (v / v) inoculum ratios. The effect of agitation speed on biohydrogen production was examined in a shaking incubator under 0 rpm / 100 rpm / 200 rpm conditions. In the studies which examined the effects of the substrate concentration and temperature, bioreactors containing production media of 10,8, 16,2, 21,6, 27 and 32,4 g COD / L concentrations were inoculated with a ratio of 1:10 (v / v). Fermentations were performed at 28° C and 37° C. The relationship between substrate concentration and product production was evaluated using elementary reaction rate model, Michaelis-Menten reaction rate model and modified Gompertz models. Results: The most suitable parameters were determined as agitation speed 200 rpm, microorganism inoculum ratio 1:10 v/v, initial substrate concentration 32.4 g COD/L and temperature 37°C. Under these conditions, 1257 mL H2production, 17.06 mL H2/g COD yield and 6.441 mL H2/L maximum H2production rate was reached. For first order elementary reaction rate model, reaction rate constant was calculated as 7.92x10-5min-1. Arrhenius constant and activation energy were calculated as 9.74×1034min-1and 229.20 kJ/mol respectively. For Michaelis-Menten model, maximum H2production rate, Michaelis constant and R2value were calculated as, 74.66 mL H2/L.min, 447.7 g COD/L and 0.9505. Using modified Gompertz model, all R2values were obtained greater than 0.99, maximum H2production potential was found as 2.777 L H2/L. Maximum H2production rate was reached as 15.250 mL H2/L.min under 27 g COD/L initial substrate concentration condition. Conclusion: The results showed that high H2production potential, highest H2production rate and low lag phase values were observed in comparison to the previously reported results in literature. © 2018 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.