Enhancement of Biohydrogen Production via Thermophilic Cell Culture Immobilized on Glass Beads and Raschig Rings of Different Sizes in a Packed Bed Reactor

E. A. Pekguzel, T. Keskin and N. Azbar

Abstract
In this study, two different types of support material of different size, namely glass bead and Raschig ring, packed in a plug flow reactor, were used in order to compare their biohydrogen production performances with that of a CSTR reactor. All experiments were conducted under thermophilic conditions (55 °C ± 2 °C). The best results in terms of volumetric hydrogen productivity were obtained with large-sized glass beads (LSG: 2.98 L H2 L–1 bioreactor day–1) at 3 h hydraulic retention time (HRT). Raschig ring materials were able to produce 42 % less hydrogen than glass beads. Hydrogen productivity in the CSTR type reactor was 0.5 L H2 L–1 bioreactor day–1. In conclusion, the immobilized cell type bioreactor configuration provided 7–11 times better results in terms of volumetric hydrogen production values compared to the CSTR reactor. It was demonstrated that both glass beads and Raschig ring type support materials, which are readily available, showed promising results for hydrogen production.

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Keywords
biohydrogen, immobilization, mixed culture, glass bead, Raschig ring