Effect of Temperature and Total Solid Content on the Dry Fermentation of Stillage
Effect of temperatures and total solid content on the dry fermentation of stillage was investigated in this study.It was found that the degradation rates of cellulose and hemicelluloses increased with the increase of temperature(from 25 ℃to 55℃),which significantly promoted the methane yield and productivity.The accumulative methane yield under 55℃ was three times higher than that under 25℃ and several gas production peaks were observed during the fermentation.When the total solid content(TS)increased from 15％to 20％,the acid accumulation was not found and the pH value in the fermen-tors stabilized around 7.0,the methane yield and volatile solid(VS)removal rate were promoted with the increase in TS content.However,further increasing the TS(25％～30％)would reduce the pH,which results in the reduction of substrate removal,restricts the fermentation processes,and finally lowers the methane yield and productivity.Thus,the 55℃ and TS content of 20％were the optimal conditions for methane production from the stillage.The results will provide some theoreti-cal foundation for the dry fermentation of the stillage.
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