Psychrophilic dry anaerobic digestion of cow dung for methane production: Effect of inoculum

Abstract

Stabilizing organic solid wastes economically is a challenge, particularly in cold and hilly regions where the temperature can be below 20 °C. Inocula sampled from psychrophilic and mesophilic environments were introduced and their effects on psychrophilic dry anaerobic digestion of cow dung for methane production at 15 °C were investigated in single-stage batch reactors for 84 days. The results showed that the specific methane yield and volatile-solid removal in the fermentation system inoculated with psychrotroph flora had been enhanced by 28.3% and 28.6%, respectively, compared to a system inoculated with mesophilic flora. Furthermore, the start up and performance of the process had been improved. The specific methane yield was greatest when the psychrophilic dry anaerobic fermentation process was inoculated with a weight of 50% of the substrate, among the systems with psychrophilic inocula of 30%, 50%, and 70%.