Optimization and modelling of dark fermentative hydrogen production from cheese whey by Enterobacter aerogenes 2822

In India, annually about 3.3-5 million tons of cheese whey is produced which may causes serious problems for the environment if left untreated. In this study, pretreated cheese whey was utilized to produce hydrogen via dark fermentation by Enterobacter aerogenes 2822 cells in 2 L double walled cylindrical bioreactor having working volume of 1.5 L. Effect of change in total carbohydrate concentration in cheese whey (CWTC, 20-45 g L-1), temperature (T, 25-37 degrees C) and pH (5.5-7.5) was investigated on volumetric hydrogen production rate (VHPR) using Box Behnken design (BBD). Experimental VHPR of 24.7 mL L-1 h(-1) was attained at an optimum concentration of 32.5 g L-1 CWTC, 31 degrees C T and 6.5 pH, which was in good correlation with predicted rate of 23.2 mL L-1 h(-1). Mathematical models based on Monod and logistic equations were developed to describe the kinetics of substrate consumption and growth profile of E. aerogenes 2822 under optimum conditions. While for the modelling of fermentative hydrogen production in batch mode, Modified Gompertz equation and Leudeking-Piret models were used which gave proper simulated fitting. These results will add significant values to cheese whey by converting it into a clean form of bioenergy. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.