Parametric Optimization of Biohydrogen Production from Potato Waste and Scale-Up Study Using Immobilized Anaerobic Mixed Sludge

Abstract

Response surface methodology (RSM) using the central composite design (CCD) approach was used in the parametric optimization of biohydrogen production from potato waste and the scale-up study was investigated using immobilized anaerobic mixed sludge. A two-level-four-factor (24)-CCD obtained via a statistical software (STATISTICA 8 release 7) was used to generate 26 fermentation experiments. The experimental results were used to generate a second-order polynomial regression equation relating the biohydrogen production to the parameters considered (potato waste concentration, pH, temperature, and fermentation time). The optimum conditions for biohydrogen production were 39.56 g/L, 7.86, 37.87 °C and 82.58 h for potato waste concentration, pH, temperature, and fermentation time, respectively with a corresponding biohydrogen yield of 68.54 mL H2/g total volatile solids (TVS). A coefficient of determination (R2) of 0.99 was obtained by solving the polynomial regression equation. The obtained optimized conditions were further validated experimentally resulting in biohydrogen yield of 79.43 mL H2/g TVS, indicating a 15.9% biohydrogen increase. Scale-up conducted at the validated optimized conditions with the immobilized bacteria generated 298.11 mL H2/g TVS with maximum fraction of 56.38%. Therefore, these results demonstrate the potential of up-scaling biohydrogen production using immobilized bacteria which could be instrumental towards its large-scale production.