Determination of Anaerobic Co-fermentation of Brewery Wastewater and Brewer's Spent Grains for Bio-hydrogen Production

The present study evaluated the anaerobic co-fermentation of brewery by-products for hydrogen production. The biochemical hydrogen potential was conducted at thermophilic (55 degrees C) and acidogenic conditions (pH around 5) mixing brewery wastewater, brewer's spent grains (BSG), and sludge from the brewery wastewater treatment plant. The results revealed that the removal efficiency of total volatile solids (TVS) reached a maximum of 30.86%. The dominant volatile fatty acids produced were acetic (3648.86 mg L-1) and butyric (2300.22 mg L-1), while propionic (765.56 mg L-1) and isovaleric (827.80 mg L-1) were detected in much lower amounts. The reactor operated only with wastewater decreased the nitrogen concentration at the end of co-fermentation (190 mg N-NH3 L-1), while the addition of BSG promoted an increase of nitrogen (>300 mg N-NH3 L-1). The highest hydrogen yield was obtained for the reactor operated only with wastewater (25.11 mL H-2 g(-1) TVS), and the yield decreased according to the addition of BSG, reaching 9.55 mL H-2 g(-1) TVS for the reactor containing 17.5% of BSG. The suppression of hydrogen production with BSG addition can be associated with the ammonia inhibition. The Gompertz, Cone, and first-order kinetic models predicted the hydrogen production with a difference lower than 1.5% of the experimental volume obtained. Finally, this study advanced our knowledge regarding the use of BSG and the inhibition of hydrogen production due to excessive ammonia generation during the dark fermentation of brewery by-products.