Measurement of H2 consumption and its role in continuous fermentative hydrogen production

To maximise the yield from fermentative H(2) production, H(2) consumption must be minimised. This work demonstrated for the first time that H(2) consumption exists in an established continuous-flow biohydrogen system. The rate of H(2) consumption was found to be related to the concentration of CO(2), with H(2) consumption inhibited at both low and high CO(2). N(2) sparging of the continuous reactor at 31 mL/min/L-liquid increased the H(2) yield from 1.31 to 1.87 mol H(2)/mol glucose, but did not significantly change the in-situ rate of H(2) consumption (0.07-0.09 mM/h). Assuming sparging completely inhibited H(2) consumption, it could only account for 2-11% of the H(2) yield increase during sparging, based on H(2) consumption rates measured in the reactor and in vials. Therefore, H(2) consumption may be of minor concern for continuous biohydrogen systems.