Evaluation of the stability of hydrogen production and microbial diversity by anaerobic sludge with chloroform treatment

The stability of biological H2 production and microbial diversity by anaerobic sludge treated chloroform with different concentrations were investigated in this work. Taking into account the cumulative H2 production, H2 percentage, maximum H2 production rate, H2 yield and substrate utilization efficiency together, 0.050% of CHCl3 concentration was found to be appropriate for enhancing anaerobic H2 production. The repeated batch tests revealed a good stability of H2 production with the inocula treated by chloroform at different concentrations. Denaturing gradient gel electrophoresis (DGGE) analysis demonstrates that CHCl3 showed desirable selective inhibition on methanogens, rather than H2-producing bacteria. The favorable microbial communities for fermentative H2 production by anaerobic sludge were uncultured bacterium clones nbt176c01, Janthinobacterium sp.7, Megasphaera paucivorans strain VTT E−03234, Clostridium cellulosi strain D3 and Clostridium sp. HPB-4.

► The feasibility applying chloroform with different concentrations to enrich H2-producing bacteria in anaerobic sludge was explored.
► The H2 production stability was evaluated by a repeated batch mode and microbial community structure was also investigated using denaturing gradient gel electrophoresis.
► Considerable improvement of dark fermentative H2 production was achieved by using chloroform treatment.