Biohydrogen production by co-digesting whey and glycerin in an AnSBBR: Performance optimization, metabolic pathway kinetic modeling and phylogenetic characterization

• Published in: Biochemical engineering journal Vol. 128; pp. 93 - 105
• Main Authors: Lovato, G., Lazaro, C.Z., Zaiat, M., Ratusznei, S.M., Rodrigues, J.A.D.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-12-2017
• Subjects: Ethanoligenens; Hydrogen; Megasphaera; Metabolic model; SBR; Metabolic model; SBR; Megasphaera; Hydrogen; Ethanoligenens
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2017.09.011

•H2 production from co-digestion of cheese whey and glycerin in AnSBBR.•Best condition: 75% of cheese whey, 25% of glycerin, AVOL 23.9kgCODm−3d−1.•Productivity gain was 145% and 27% comparing to AD of whey and glycerin alone.•A kinetic model was fitted to data to help the understanding of the metabolic routes.•The dominant bacteria were affiliated to Ethanoligenens and Megasphaera genera.
The co-digestion of cheese whey with glycerin for biohydrogen production, in an anaerobic sequencing batch biofilm reactor (AnSBBR) with recirculation of the liquid phase (at 30°C with 3.5L of working volume and treating 1.5L per cycle), was assessed. The feeding time (1.5h) was equal to half of the cycle length (3 h). Two variables were studied: the ratio between whey and glycerin (100:0; 75:25; 50:50; 25:75; 0:100% on a COD basis) and the organic loading rate (from 10.1 to 23.9kgCODm−3d−1) by altering the influent concentration (from 3 to 7kgCODm−3). The highest hydrogen productivity (129.0molH2m−3d−1) and yield (5.4molH2kgCOD−1) with complete inhibition of methanogenisis were achieved when the reactor was fed with 75% cheese whey and 25% glycerin with an applied volumetric organic load of 23.9kgCODm−3d−1; an increase in productivity of almost 145% and 27% when compared to the anaerobic digestion of cheese whey and glycerin separately, respectively, showing the significant benefit of glycerin addition for anaerobic whey digestion, most likely due to its buffering capacity. A kinetic metabolic model was efficiently fitted to the process to help understand the metabolic routes. Cloning analyses targeting 16S rRNA genes indicated the dominant microorganisms were phylogenetic affiliated to Ethanoligenens and Megasphaera genera.