As shown in Table 6, reduced particle size of straw indeed could
improve the gas production, but not mean that the smaller straw
diameter the higher gas production. Under the optimal FW/Straw
ratio of 5:1 with total organic load of 6 g VS/L, the highest GP
reached 0.52m3/kg-VS when the straw were 0.45e0.6 mm, and the
methane content and the MPY reached 60.29% and 0.31m3 CH4/kg-
VS, respectively. However, given the economical efficiency and
energy-saving, straw particle size of 0.3e1 mm could be applied.