When KW and PM were added to RS at a ratio of 0.8:1.2, reactor C produced 29.6 mL/(g VS d) of biogas on the first day, containing a low CH4 concentration of 18.7% and a small H2 fraction of 0.4%, as well as a high CO2 concentration of 67.4%; this indicates that fermentation was due to acidogenesis during this period (Kleyböckeret al., 2012).