Experimental investigation of dark fermentation of poplar leaves for biohydrogen production

Abstract

Biohydrogen, a sustainable and environmentally friendly energy alternative, is pivotal in transitioning to a more energy-efficient future. Thesis research explores the variations of H2 hydrogen production potential of poplar leaves as a substrate for biohydrogen production via dark fermentation, an underexplored area. Through a series of 58 experimental trials, insightful findings were obtained about the hydrogen production process. The Gompertz function is used to model the experimental trial results which represent cumulative hydrogen production rate. The hydrogen production rate varies between 0.14 to 2.73 ml/h. Moreover, variations were observed in the maximum hydrogen production per gram of substrate, between 0.02 ml/g to 0.46 ml/g. The ideal maximum hydrogen using the experimental data. production rate was estimated at approximately 0.2 ml/h, with an optimal time constant of about 1 hour. A comprehensive analysis of influential parameters was conducted using Design-Expert statistical software, identifying biomass quantity as a critical determinant of hydrogen production. The research also identified optimal operational conditions for maximizing hydrogen production: an acid concentration of 10%, a biomass quantity of 2.009 grams, an initial pH of 7.65, a temperature of 39.9 °C, and a mixing ratio of 325.66 rpm. These conditions were projected to produce a maximum hydrogen production of 0.76 mL/g. The results suggest that a biochemical reactor designed in this study effectively reduced the salinity of water and chemical oxygen demand (COD) of biomass by approximately 51% and 75%, respectively.