Biohydrogen production from soft drink industry wastewater in an anaerobic fluidized bed reactor

Abstract

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.