Abstract
In this study, the effects of bioactive reagent (saponin) on the anaerobic digestion were investigated. In order to clarify the effectiveness of saponin, continuous experiments with the presence of saponin were conducted at mesophilic temperature (38°C) on the mixed substrate of night soil and garbage. The amounts of added saponin were 0, 20, 50ppm. The obtained results are as follows.
1) The rates of hydrolytic, acidogenenic and methanogenenic were increased by the saponin addition. The increments of the rates were 1.3, 1.4 and 1.2 times, respectively. These result shows that the addition of saponin is effective for upgrading of anaerobic digestion. The acidogenesis rate was especially increased.
2) The increment of acidogenenic rate was 1.2 times higher than that of methanogenesis by the saponin addition. This caused the accumulation of volatile fatty acid. It indicates that methanogenesis is rate-limiting step in the over all process of anaerobic digestion.
3) Compared with the results of 20ppm and 50ppm of saponin addition, there was little difference between all process of anaerobic digestion. It seems that the addition of 20ppm of saponin is enough for the rate increase of the reaction at the condition of this study.
