Application of a novel biological-nanoparticle pretreatment to Oscillatoria acuminata biomass and coculture dark fermentation for improving hydrogen production

Abstract

BackgroundEnergy is the basis and assurance for a world's stable development; however, as traditional non-renewable energy sources deplete, the development and study of renewable clean energy have emerged. Using microalgae as a carbon source for anaerobic bacteria to generate biohydrogen is a clean energy generation system that both local and global peers see as promising.ResultsKlebsiella pneumonia, Enterobacter cloacae, and their coculture were used to synthesize biohydrogen using Oscillatoria acuminata biomass via dark fermentation. The total carbohydrate content in O. acuminata was 237.39 mg/L. To enhance the content of fermentable reducing sugars, thermochemical, biological, and biological with magnesium zinc ferrite nanoparticles (Mg-Zn Fe2O4-NPs) pretreatments were applied. Crude hydrolytic enzymes extracted from Trichoderma harzianum of biological pretreatment were enhanced by Mg-Zn Fe2O4-NPs and significantly increased reducing sugars (230.48 mg/g) four times than thermochemical pretreatment (45.34 mg/g). K. pneumonia demonstrated a greater accumulated hydrogen level (1022 mLH2/L) than E. cloacae (813 mLH2/L), while their coculture showed superior results (1520 mLH2/L) and shortened the production time to 48 h instead of 72 h in single culture pretreatments. Biological pretreatment + Mg-Zn Fe2O4 NPs using coculture significantly stimulated hydrogen yield (3254 mLH2/L), hydrogen efficiency)216.9 mL H2/g reducing sugar( and hydrogen production rate (67.7 mL/L/h) to the maximum among all pretreatments.ConclusionThese results confirm the effectiveness of biological treatments + Mg-Zn Fe2O4-NPs and coculture dark fermentation in upregulating biohydrogen production.