Enhanced biohydrogen production from beverage industrial wastewater using external nitrogen sources and bioaugmentation with facultative anaerobic strains

•Bioaugmentation of E. coli and heat-treated sludge enhance hydrogen production.•Addition of external nitrogen sources yeast extract and tryptone significantly improve hydrogen formation.•Peak hydrogen production attained at 5 g COD/L of beverage wastewater.

In this work biohydrogen generation and its improvement possibilities from beverage industrial wastewater were sought. Firstly, mesophilic hydrogen fermentations were conducted in batch vials by applying heat-treated (80°C, 30 min) sludge and liquid (LB-grown) cultures of Escherichia coli XL1-Blue/Enterobacter cloacae DSM 16657 strains for bioaugmentation purposes. The results showed that there was a remarkable increase in hydrogen production capacities when facultative anaerobes were added in the form of inoculum. Furthermore, experiments were carried out in order to reveal whether the increment occurred either due to the efficient contribution of the facultative anaerobic microorganisms or the culture ingredients (in particular yeast extract and tryptone) supplied when the bacterial suspensions (LB media-based inocula) were mixed with the sludge. The outcome of these tests was that both the applied nitrogen sources and the bacteria (E. coli) could individually enhance hydrogen formation. Nevertheless, the highest increase took place when they were used together. Finally, the optimal initial wastewater concentration was determined as 5 g/L.