Biohydrogen production in cassava processing wastewater using microbial consortia: Process optimization and kinetic analysis of the microbial community

[Display omitted] •Two heat-treated new microbial consortia were used for the production of H2.•The conditions for the production of bioH2 were optimized for both consortia.•The kinetic parameters µ, g, k, and q were higher in both consortia in hydrolyzed media.•Relative abundance of microorganisms changes during the fermentation process. Biohydrogen production was evaluated using cassava processing wastewater (CPW) and two microbial consortia (Vir and Gal) from different Brazilian environments. The biohydrogen production was optimized using a Box-Behnken design (T, pH, C/N, and % v/v inoculum). Maximum yields were obtained with hydrolyzed substrate: 4.12 and 3.80 mol H2 / for Vir and Gal, respectively. Similarly, the kinetic parameters µ, k, and q were higher with hydrolyzed CPW in both consortia. The molecular analysis of the consortia through Illumina high-throughput sequencing showed the presence of bacteria from the families Porphyromonadaceae, Clostridiaceae, Ruminococcaceae, and Enterococcaceae. The relative abundance of microbial families varies as fermentation progresses. In both consortia, Clostridiaceae reached the maximum relative abundance in the media between 16 and 24 h, interval in which approximately 90% of the biohydrogen is generated.