Production of methane gas from Japanese cedar chips pretreated by various delignification methods

Methane fermentation of woody waste was carried out using various pretreatment methods for delignification in order to evaluate the efficient pretreatment method for producing methane gas from woody waste. Japanese cedar (Cryptomeria japonica) chips were used as sample of woody waste. As pretreatment methods, refiner treatment, steaming treatment, steaming treatment followed by refiner treatment, basidiomycete fungi treatment, and steam explosion treatment were attempted and the methane gas evolved from treated wood chips were compared. The steam explosion treatment resulted in the most effective pretreatment method for methane fermentation from woody waste among the pretreatment methods. The steam explosion at a steam pressure of 4.51 MPa and a steaming time of 5 min was the optimal pretreatment method for obtaining a large amount of methane gas in energy saving manner. The strong correlation between the amount of methane gas evolved and the ratio of amount of Klason lignin was observed. The study confirmed the necessity of pretreatment for delignification of cedar wood waste.