Kinetics of methane production and hydrolysis in anaerobic digestion of corn stover.

In order to develop a time-saving method for determination of ultimate methane production, obtain the hydrolysis kinetic constant, and identify a determination method for the nonbiodegradable organic fraction of substrate ( VS NB ) of green and air-dried corn stover, the kinetics of methane production and hydrolysis were studied using batch tests. The results showed that the conventional first-order hydrolysis kinetic model was not suitable for describing the entire hydrolysis process of corn stover, because there were two first-order decay periods for hydrolysis of corn stover. The hydrolysis kinetic constants k H,1 and k H,2 of the first and second periods were 0.1701 and 0.0415 1/d for green stover and 0.1052 and 0.0360 1/d for air-dried stover. The value of VS NB could be obtained by the graphical method rather than by the hydrolysis kinetic model. The obtained VS NB contents were 12.9% and 24.7% of VS (volatile solid) for green and air-dried stover, respectively. The ultimate methane production and corresponding digestion time could be understood through the methane production kinetic model by digestion experiments within a short time. The ultimate methane productions were 347.1 and 319.4 mL/g based on VS and the corresponding digestion times were 69.2 and 182.3 days for green and air-dried stover, respectively. [ABSTRACT FROM AUTHOR]