Analysis of Biogas Component Production during Anaerobic Digestion of Sour Cabbage in Microaeration Conditions under Different pH Conditions

Influences of following anaerobic digestion (AD) parameters like microaeration, pH, and VSS (Volatile Suspended Solid) using sour cabbage as substrate was checked in the publication. Results of fermentation of sour cabbage under the condition of small oxygen addition presented in this research can be classified as dark fermentation (DF—a special case of AD) or hydrogenotrophic anaerobic digestion. The investigations were carried out for two concentrations of 5 g VSS/L and 10 g VSS/L of sour cabbage at pH 6.0. The oxygen flow rates (OFR) for 5 g VSS/L were in the range of 0.53 to 3.3 mL/h for obtaining 2% to 8% of oxygen. At low pH and microaeration, ethylene production was observed at a level below 0.05% in biogas. The highest volume of hydrogen for 5 g VSS/L was obtained for flow rate 0.58 O2 mL/h, giving hydrogen concentration in biogas in the range of 0 to 20%. For VSS 5 g/L and oxygen flow rate 0.58 mL/h; 0.021 L of hydrogen was produced per gram of VSS. At VSS 10 g/L and oxygen flow rate 1.4 mL/h at pH 6.0, 0.03 L of hydrogen was generated per gram. Microaeration from 0.58 mL/h to 0.87 mL/h was propitious for hydrogen production at 5 g VSS/L of sour cabbage and 1.4 mL/h for 10 g VSS/L. Another relevant factor is the volatile suspended solid factor of a substrate. Optimal hydrogen production from sour cabbage was for VSS 89.32%.