| Title |
Effects of pCO2 on the Characteristics of Organic Matter Degradation , Bacterial Trophic Populations and Metabolic Activity in Methanogenic Phase |
| Abstract |
Effects of CO₂ Partial pressure(pCO₂) on the characteristics of organic matter degradation, bacterial trophic populations and metabolic activity in methanogenic phase has been investigated by using CSTR anaerobic digester fed with VFA(Volatile fatty acids) as the major organic carbon source. Three kinds of single substrates contain acetic, propionic, and butyric acid were used in this study. The pCO₂ of the methanogenic phase was controlled in the range from 0.2 to 0.8atm. The substrate removal efficiency decreased significantly when pCO₂ exceeded 0.7atm at the acetic acid reactor. The substrate removal efficiency of propionic acid and butyric acid were not much influenced by the change in pCO₂. The number of acetate consuming methanogenic bacteria(AMB) and H₂ consuming methanogenic bacteria(HMB) enumerated by the most probable number method, decreased when pCO₂ exceeded 0.7atm. pCO₂ does not have much effect on the bacterial numbers of sulfate reducing bacteria, bacteria degrading propionate and butyrate. The specific substrate utilizing activity(SUA) and specific methanogenic activity(SMA) of AMB increased as pCO₂ increased from 0.3 to 0.6atm. It was considered that the inhibition of methanogenic bacteria at pCO₂ above 0.7atm would depend on free CO₂ concentration in solution. |