Abstract
The surface characteristics, including rheological, fractal characteristics, hydrophobicity as well as surface free energy, of H2-producing sludge in acidogenic fermentative process were investigated in this study. Both rheological and fractal characteristics of the H2-producing sludge changed slightly in the acidogenesis. The sludge fractal dimension was larger than those of other microbial aggregates, whereas the affinity of the microbial cells for the hydrocarbon had a peak value in the fermentation process. Both specific H2 and volatile fatty acids/ethanol production rates of the sludge had a peak of 108 mL-H2 L-1 h-1 g-VSS-1 and 480 mg L-1 h-1 g-VSS-1. There was a relationship between the hydrophobicity of the H2-producing sludge and its specific H2-producing activity. The surface free energy of the H2-producing microorganisms had a lowest value in their growth process.
