Biogenic H₂ production from mixed microalgae biomass: Impact of pH control and methanogenic inhibitor (BESA) addition

Hydrogen production from mixed microalgae biomass, predominantly containing Scendesmus and chlorella species, was investigated with a focus on enhancement strategies, in particular (i) pH control (at 5.5) and (ii) methanogenic inhibitor (BESA) addition along with pH control at 5.5. The results obtained showed that the later condition remarkably increased the performances. This was mainly ascribed to the occurrence of a suitable environment for the hydrogen producers to perform actively. Hydrogen production under these conditions (i.e., both pH 5.5 and pH 5.5+BESA) was significantly higher than that of the control experiment. Using the pH control at 5.5 and BESA addition, peak hydrogen production rate (HPR) and hydrogen yield (HY) were attained as 210 mL/L/d and 29.5 mL/g VS_added, respectively. This improvement was nearly 3-folds higher compared with the control experiment with an HPR of 62 mL/L/d and an HY of 9.5 mL/g VS_added.