Photobiohydrogen production and high-performance photobioreactor - Solar Energy Sciences and Engineering Applications - page 364

Figure 11.4.7 The groove-type photobioreactor (Zhang et al., 2010).
inhibition. In addition, long term retention of biomass promotes the application of the
biofilm technique in industrialization. Therefore, the immobilized-cell system with the
biofilm formation is regarded as a more promising technique for continuous photo-
biohydrogen production (Hallenbeck and Benemann, 2002). Typically, the biofilm can
be formed onto the inner surface of the photobioreactor surface or packed materials
surface, which have been widely explored.
Tsygankov et al. (1993) found that the planar glass surface modified by silane cou-
pling reagents could improve the hydrophobicity of the surface, which greatly increased
the bacterial attachment. In addition, Zhang et al. (2010) developed a groove-type
photobioreactor (Figure 11.4.7), in which the grooves were successfully incised on a
transparent panel for the cell immobilization. Their results showed that the perfor-
mance of the photobiohydrogen production of the groove-type photobioreactor was
about 75% higher than that of the flat panel photobioreactor due to the enriched
immobilized biomass, the higher specific surface area of the photobioreactor and
enhanced convective mass transfer for both substrate and metabolic products of the
photo-fermentation. Liao's team in Chongqing University has also carried out extensive
works on the biofilm technique for the photobiohydrogen production. They used a thin
glass slide as carrier to immobilize photosynthetic bacteria in a flat panel photobioreac-
tor and manufactured a transparent microchannel photobioreactor (Figure 11.4.8) to
visualize the colony formation of photosynthetic bacteria, Rhodopseudomonas palus-
tris CQK 01, as well as the biogas bubble behavior within the microstructure (Liao
et al., 2010; Qu et al., 2011; Wang et al., 2011). The results showed that the biomass
concentration, light penetration and mass transport were significantly affected by the
biofilm microstructure.
It should be mentioned that the cell immobilization on the planar surface has a
problem of low specific surface area. Immobilizing cells on the solid particles or fibers