Abstract
The wastewater from carbonated soft drinks production was used as substrate in an anaerobic fluidized bed reactor (AFBR) to evaluate the production of biohydrogen as a renewable energy. The hydraulic retention time (HRT) ranged from 8 to 0.5 hours (7.92 to 137.09 kg COD m−3 day−1) throughout the experiment and expanded clay was used as support material for biomass adhesion. The average composition of hydrogen in the biogas under the conditions of this experiment was 34%. The maximum hydrogen yield (HY) and the maximum hydrogen production rate (HPR) was 5.87 mol H2/mol substrate and 2.74 L H2 h−1 L−1, respectively, obtained in the HRT of 0.5 hour. Acetic acid was the predominant soluble metabolite detected (88%). Propionic, butyric and caproic acids were quantified with low production (7%, 4% and 1% of soluble metabolites production (SMP)). The anaerobic fluidized bed reactor optimized the average of hydrogen yield by 17% in relation to packed-bed reactors, in a HRT of 0.5 h. The natural fermentation process and operating conditions were favorable to the inhibition of hydrogen-consuming organisms, such as methanogenic archaeas.