Environmental Engineering Reference
Stage II: Photofermentation (photosynthetic bacteria)
In the irst step, biomass is fermented to acetate, carbon dioxide, and
hydrogen by thermophilic dark fermentation, while in the second step, acetate
is converted to hydrogen and carbon dioxide.
Starch, cellulose or hemicellulose content of wastes, carbohydrate rich
food industry efluents or waste biological sludge can be further processed
to convert the carbohydrates to organic acids and then to hydrogen gas by
using proper bioprocessing technologies. Figure 4.4 shows schematic diagram
for biohydrogen production from food industry wastewaters and agricultural
wastes by two stages, anaerobic dark and photofermentations .
FIGURE 4.4 A schematic diagram for biohydrogen production from cellulose/starch containing agri-
cultural wastes and food industry wastewaters. Source : Reproduced with permission from Kapdan and