Investigation of possible synergic effects of different exoelectrogenic bacteria combinations on hydrogen production via microbial electrolysis

In this study, microbial electrolysis and fermentation experiments were performed at 0.5; 0.7 and 1.0 V application potentials using Shewanella oneidensis MR-1 and Geobacter metallireducens bacteria cultures in presence of anaerobe sludge and a standard solution (glucose (60 g/L), peptone (10 g/L), yeast extract (0,6 g/L), MgSO4.7H2O (0,25 g/L), K2HPO4 (1 g/L), KH2PO4 (1 g/L), L-cysteine HCl.H2O (0,1 g/L) ve NaCl (2 g/L)). The cell used in microbial electrolysis was set up in one compartment with a special design. The experiments were carried out at two different temperatures (30 and 35ºC) via continuously mixing in 300 rpm for 19 hours. The electrodes used in these experiments were Pt gauze as anode and cathode; EPPG as anode and 5%Pt doped EPPG as cathode. The microbial electrolysis of Shewanella oneidensis MR-1 and Geobacter metallireducens mixture by using Pt gauzes electrodes at 0.5 V potential produced 1405 ml of gas mixture which composed of 37.2% of hydrogen. When same experiments were perfomed with Geobacter metallireducens bacteria culture using EPPG electrodes, 1220 ml of gas mixture that consisted of 42.2% of hydrogen were generated. The rest of gas composition in all electrolysis experiments was CO2.