Hydrogen production potential comparison of sucrose and crude glycerol using different inoculums sources

The hydrogen production potential from crude glycerol was evaluated using a batch test, at four different food microrganisms ratios (F/M) and the results were compared with sucrose, a substrate considered a degradation model. It was used two different inoculums, one generated by natural fermentation of the used substrates and the other by direct inoculum, using pretreated anaerobic sludge. The obtained results indicated low hydrogen potential production using natural inoculum. The predominant volatile fatty acids (VFA) were acetic and butyric acids, and when used direct inoculation, the acidification degree reached of up to 50%. The productivities were close to and even higher than those obtained with sucrose, with direct inoculum, reaching a maximum value of 8.5 mL H-2/L center dot h at F/M 2. It was observed a decrease of the crude glycerol conversion efficiency when higher F/M ratios were used, possible by high concentrations of glycerol cause an inhibitory effect on H-2 production.