Characterization and potential of three temperature ranges for hydrogen fermentation of cellulose by means of activity test and 16s rRNA sequence analysis

• The characterization of three temperature ranges of H2 fermentation was evaluated.
• The H2 gas produced effectively at 55 and 65 °C, while the CH4 produced at 35 °C.
• The highest activity of 521 mL H2/g VSS d was obtained by TMC at 55 °C.
• The H2 producing bacteria were close to Enterobacter genus in the MMC.
• The H2 producing bacteria were close to Thermoanaerobacterium in the TMC & HMC.

A series of standardized activity experiments were performed to characterize three different temperature ranges of hydrogen fermentation from different carbon sources. 16S rRNA sequences analysis showed that the bacteria were close to Enterobacter genus in the mesophilic mixed culture (MMC) and Thermoanaerobacterium genus in the thermophilic and hyper-thermophilic mixed cultures (TMC and HMC). The MMC was able to utilize the glucose and cellulose to produce methane gas within a temperature range between 25 and 45 °C and hydrogen gas from 35 to 60 °C. While, the TMC and HMC produced only hydrogen gas at all temperature ranges and the highest activity of 521.4 ml H2/g VSS d was obtained by TMC. The thermodynamic analysis showed that more energy is consumed by hydrogen production from cellulose than from glucose. The experimental results could help to improve the economic feasibility of cellulosic biomass energy using three-phase technology to produce hythane.

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