Influence of pH on fermentative hydrogen production from sweet sorghum extract

Georgia Antonopoulou, Hariklia N. Gavala, Ioannis V. Skiadas, Gerasimos Lyberatos

Research output: Contribution to journalJournal articleResearchpeer-review


The present study focused on the influence of pH on the fermentative hydrogen production from the sugars of sweet sorghum extract, in a continuous stirred tank bioreactor. The reactor was operated at a Hydraulic Retention Time of 12 h and a pH range of 3 5-6 5 The maximum hydrogen production rate and yield were obtained at pH 5 3 and were 1752 54 ml. H2/d or 3.50 +/- 0 07 L H2/L reactor/d and 0 93 +/- 0 03 mol H2/mol glucose consumed or 10.51 L H2/kg sweet sorghum, respectively The main metabolic product at this pH value was butyric acid The hydrogen productivity and yield were still at high levels for the pH range of 5 3-4 7, suggesting a pH value of 4 7 as optimum for hydrogen production from an economical point of view, since the energy demand for chemicals is lower at this pH At this pH range, the dominant fermentation product was butyric acid but when the pH culture sharply decreased to 3 5, hydrogen evolution ceased and the dominant metabolic products were lactic acid and ethanol.
Original languageEnglish
JournalInternational Journal of Hydrogen Energy
Pages (from-to)1921-1928
Publication statusPublished - 2010
Externally publishedYes


  • Sweet sorghum
  • Hydrogen
  • pH
  • Continuous fermentation
  • Biohydrogen


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