Bioenergy recovery from food waste through dark fermentation direction

Abstract

Abstract The increase in food waste generation has encouraged the scientific community to convert it into value-added resources. Hydrogen energy provides a sustainable option to fossil fuels due to its purity, high energy content, and reduction of global warming. This study investigates the batch fermentative biohydrogen production from food waste, which takes into account the effects on the process stability and energy recovery. Experiments were carried out at different ranges of pH (5.5, 6.0, and 6.5), FW concentration (1, 5, 10, 15, 20, 25, and 30 g-VS/L) at mesophilic (37˚C) and thermophilic (55˚C) temperature through 24h incubation of batch dark fermentation process. The FW concentration of 15–20 g-VS.L− 1 was found to be the proper concentration for biohydrogen production at 55˚C fermentation with the highest yield of 80.41 ml-H2/g-VS.L− 1, hydrogen content of 76.53%, at pH 6.0. Under mesophilic temperature, a lower hydrogen yield of 49.36 ml-H2/g-VS.L− 1and hydrogen content of 60.53% was produced in the same substrate concentration and pH. The COD removal efficiencies at 37 ˚C and 55 ˚C increased from 16.66–21.87%, and 20.83–29.09% at pH 6.0 with an increase in FW concentration from 1 to 20 g-VS.L− 1. Further increase in FW concentration showed less yield of hydrogen production. From pyrosequencing analysis, hydrogen fermentation at both temperatures was attributed to Lactobacillus and Clostridium sensu stricto 1, which confirms the potential of the microbial community for biohydrogen production.