| The method of anaerobic solid-state digestion was used to examine the effects of different total solid contents on methane yield and organic removal rate from distiller′s grains and food waste at total solid content of 15%, 20%, 25% and 30% with activated sludge as inocula. Combined with various procedure parameters such as VFA, alkalinity and pH value, solid-state fermentation process was also analysed. The results showed that due to the high nutrient content, increasing total solid content within a certain extent could boost the production of methane, but decrease reaction speed and prolong fermentation period because of low metabolites from microbiology. After 50-days of fermentation, the highest accumulated methane yield of all the groups was 238.48 mL·g-1 TS at total solid content of 25% with optimal TS removal of 55.65% and VS removal of 72.15%. Keeping increasing total solid content lead to less methane yield. The irreversible acidification of the digestion resulting from the rapid hydrolysis and acidogenesis was the major challenge in solid-state anaerobic digestion considering that it could inhibit methanogenesis or dictate the failure of the digestion. And the higher total solid content could cause more obvious inhabitation. In addition, the cumulative methane production rate basically fitted the first order kinetic model, and R2 of all the groups were higher than 0.94. As the total solid contents increased, methane producing potential enhanced, the kinetic constants slowed down and the degree of compliance with the model lowered gradually. |
