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

In this work, effects of agitation speed, inoculum ratio, initial substrate concentraion and incubation temperature were investigated for anaerobic biohydrogen production. 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 degrees C. Under these conditions, 1257 mL H-2 production, 17.06 mL H-2/g COD yield and 6.441 mL H-2/L maximum H-2 production rate was reached. For first order elementary reaction rate model, reaction rate constants were calculated as 6.5x10(-5) min(-1) and 7.92x10(-5) min(-1) for temperatures of 28 degrees C and 37 degrees C, respectively. Arrhenius constant and activation energy were calculated as 9.74x10 34 min(-1) and 229.20 kJ/mol respectively. For Michaelis-Menten model, maximum H-2 production rates, Michaelis constants and R-2 values were calculated as 11.47 mL H-2/L.min, 74.66 mL H-2/L.min, 181.9 g COD/L, 447.7 g COD/L and 0.9458, 0.9505 for 28 degrees C and 37 degrees C temperatures, respectively. Using modified Gompertz model, all R-2 values were obtained greater than 0.99, maximum H(2 )production potentials were found as 2.126 L H-2/L, 2.777 L H-2/L at 28 degrees C and 37 degrees C with 32.4 g COD/L, respectively. Maximum H-2 production rate was reached as 15.250 mL H-2/L.min at 37 degrees C and 27 g COD/L initial substrate concentration.