Stimulating the Fermentation Process of Industrial Food Waste via Nonionic Surfactant/Graphene Nanosheet Combined Supplementation

The synergistic impact of Tween 80 (T80) and reduced graphene oxide (RGO) on the codigestion process of food waste and biscuit wastewater via an anaerobic sequential batch reactor was investigated in this study. The T80/RGO-amended reactor exhibited a hydrogen yield of 313.2 ± 89.3 mL/gCOD_initial, which is 1.98-fold higher than that of the control. This increase was a consequence of the increase of hydrogenase enzyme activity from 0.24 ± 0.11 to 0.46 ± 0.15 mg MB_reduced/min, as well as the stimulation of hydrolytic enzyme activities (i.e., α-amylase, xylanase, CM-cellulase, polygalacturonase, protease, and lipase). Likewise, microbial community analysis revealed that the relative abundances of genera Acinetobacter, Syntrophomonas, and Clostridium (H₂-producing species) were enhanced from 3.9, 2.3, and 2.8% to 10.8, 9.1, and 3.6%, respectively, when T80/RGO was supplemented. On the other hand, molecular docking analysis was performed to explore the interaction of the hydrogenase protein with RGO (binding score: -10.1 kcal/mol) and T80 (binding score: -4.1 kcal/mol) as possible targets with active site residues. Eventually, supplementation of the T80/RGO mixture could stimulate the efficiency of the fermentative hydrogen process and, consequently, be used in practical engineering applications.