Effects of $PCO_2$ on Methane Production Rate and Matter degradation in Anaerobic Digestion

혐기성소화의 물질분해 및 메탄생성에 대한 $CO_2$ 분압의 영향

Effects of carbon dioxide partial pressure(PCO2) on bacterial population, methane production rate and matter degradation in anaerobic digestion were investigated by using anaerobic chemostat type reactors at 35$\pm$1$^{\circ}C$, at the HRT of 7 days. At PCO2 of 0.5 atm, the specific methane production rate and specific substrate removal rate reached the maximum rates. The methane production rates in the reactors fed by mixed substrate were 26% higher than those obtained under the controlled condition. The number of acetate consuming methanogenic bacteria enumerated by the MPN(most probable number) method, decreased when PCO2 exceeded 0.7 atm. Hydrogen consuming methanogenic bacteria and homoacetogenic bacteria increased as PCO2 increased from 0.1 to 0.6 atm, however, decreased slightly at PCO2 above 0.7 atm. The number of hydrolytic bacteria, sulfate-reducing bacteria and H2-producing acetogenic bacterial were not much influenced by the change of PCO2. The potential methanogenic activity reached the maximum at PCO2 0.5 atm, however, decreased significantly when PCO2 exceeded 0.7 atm, would depend on free PCO2 concentration in solution.