Enhanced biohydrogen production of anaerobic fermentation by the Fe3O4 modified mycelial pellets-based anaerobic granular sludge

Abstract

To improve the catalytic efficiency and stability of hydrogen-producing bacteria (HPB), the Fe3O4 nanoparticles modified Aspergillus tubingensis mycelial pellets (AT)-based anaerobic granular sludge (Fe3O4@AT-AGS) was developed. The Fe3O4@AT-AGS protected flora with abundant extracellular polymeric substances, which increased diversity and stability of flora in early and late stage. The porous structure enhanced mass transfer efficiency, thus promoted dominant flora transferred from lactate-producing bacteria (LPB) to HPB in middle stage. The Fe3O4 improved biomass of mycelial by 19.5 %. The enhancement of dehydrogenase and conductivity of Fe3O4 increased the HPB proportion, electron transfer, and butyrate fermentation in early and middle stage. The Fe3O4@AT-AGS enhanced HPB abundance, dehydrogenase activity and stability, and significantly inhibited propionate fermentation. The biohydrogen production and yield respectively reached 2792 mL/L and 2.56 mol/mol glucose. Clostridium sensu stricto 11 as dominant microbes reached 77.3 %. This provided strategy for alleviating inhibition of LPB and improving competitiveness of HPB during biohydrogen production.