Performance and microbial community of carbon nanotube fixed-bed microbial fuel cell continuously fed with hydrothermal liquefied cornstalk biomass

• MFC was continuously fed with hydrothermal liquefied cornstalk biomass.
• 80% of COD and TOC was removed from cornstalk hydrolysate with low BOD/COD (0.16).
• Illumina MiSeq sequencing was used to analyze the microbial structure in MFC.
• Dominant bacteria was related to cellulose degradation, and was not Proteobacteria.

Hydrothermal liquefaction (HTL) is a green technology for biomass pretreatment with the omission of hazardous chemicals. This study reports a novel integration of HTL and carbon nanotubes (CNTs) fixed-bed microbial fuel cell (FBMFC) for continuous electricity generation from cornstalk biomass. Two FBMFCs in parallel achieved similar performance fed with cornstalk hydrolysate at different organic loading rates (OLRs) (0.82–8.16 g/L/d). About 80% of Chemical oxygen demand (COD) and Total organic carbon (TOC) was removed from low-Biochemical oxygen demand (BOD)/COD (0.16) cornstalk hydrolysate at 8.16 g/L/d, whereas a maximum power density (680 mW/m3) was obtained at 2.41 g/L/d, and a smallest internal resistance (Rin) (28 Ω) at 3.01 g/L/d. Illumina MiSeq sequencing reveals the diverse microbial structure induced by the complex composition of cornstalk hydrolysate. Distinguished from Proteobacteria, which a number of exoelectrogens belong to, the identified dominant genus Rhizobium in FBMFC was closely related to degradation of cellulosic biomass.