Operational and physiological strategies for co-fermentation of solid and liquid brewery waste to produce hydrogen and organic acids using Plackett-Burman design

Autochthonous fermentative inoculum was obtained and applied in a Plackett-Burman factorial design to hydrogen production by dark fermentation, investigating the influence of the variables: initial pH (4.5-6.5), brewery wastewater (3.0-9.0 g COD. L- 1), brewery spent grain (20-40 TVS. L- 1), inoculum (1.0-3.0 g VSS. L- 1), and yeast extract (1.0-2.0 g L- 1). The condition with the maximum hydrogen production (37.06 +/- 1.55 mL g- 1 TVS) was conducted with pH of 6.5, 3.0 g TVS. L- 1 of inoculum, 9.0 g COD. L- 1 of wastewater, 20 g TVS. L- 1 of brewery spent grain, and 1.5 g L- 1 of yeast extract, which favored butyric fermentation (1764.0 mg L- 1) and predominance of Clostridium (91.1%), Prevotella (4.2%), and Lactobacillus (1.7%). These results can promote cost reduction by adjusting parameters and may pose an advance in circular economy in the brewery industry.