Nutrients balance for hydrogen potential upgrading from fruit and vegetable peels via fermentation process

The sole, dual and multi-fermentations of fruit and vegetable peels (FVPs) were investigated in order to balance nutrition hierarchy for maximizing hydrogen potential via Batch experiments. The highest volumetric hydrogen production of 2.55 +/- 0.07 L/L and hydrogen content of 64.7 +/- 3.7% were registered for multi-fermentation of M-PTBO (25% pea +25% tomato + 25% banana +25% orange). These values outperformed sole and dual fermentation. The multi-fermentation of FVPs provided sufficient nutrients and trace elements for anaerobes, where C/N and C/P ratios were at levels of 24.7 +/- 0.2 and 113.2 +/- 9.4, respectively. In specific, harmonizing of macro and micro-nutrients remarkably maximized activities of amylase, protease and lipase to 4.23 +/- 0.42, 0.035 +/- 0.002 and 0.31 +/- 0.02 U/mL, respectively, as well as, substantially incremented counts of Clostridium and Enterobacter sp. up to 5.81 +/- 0.23 x 10(5) and 2.17 +/- 0.09 x 10(6) cfu/mL, respectively. Furthermore, multi fermentation of M-PTBO achieved the maximum net energy gain and profit of 1.82 kJ/g(feedstock) and 4.11 $/kg(feedstock), respectively. Nutrients balance significantly develops bacterial activity in terms of hydrogen productivity, anaerobes reproduction, enzyme activities and soluble metabolites. As a result, overall fermentation bioprocess performance was improved.