Optimization of Hydrolysis-Acidogenesis Phase of Swine Manure for Biogas Production Using Two-Stage Anaerobic Fermentation

The traditional pig manure wastewater treatment in Taiwan has been low methane production efficiency due to unstable influent concentration, volume, and quality. Two-stage anaerobic systems, contrast, have the advantage of buffering organic loading rate first stage (hydrolysis-acidogenesis phase), allowing a more constant feeding second (methanogenesis phase). Response surface methodology was applied optimize operational period (0.5–2.0 d) initial pH (4–10) for hydrolysis acidogenesis swine (total solid 5.3%) at 35 °C batch operation mode. A methanogenesis verification experiment with optimal condition 1.5 d 6.5 using resulted peak volatile acid 7 g COD/L, (MPR) 0.3 L-CH4/L-d, yield (MY) 92 mL-CH4/g-CODre (chemical oxygen demand removed). Moreover, two-stage system including hydrolysis-acidogenesis reactor operating provided an average MPR 163 mL/L-d MY 38 mL/g solids, which values are 60% higher than those single-stage system; both systems similar dominant methane-producing species Firmicutes Bacteroidetes each having around 30%–40%. advantages fermentation treating biogas obvious.