This suggests that’s that the PPW-1 was inhibited by the generated higher concentration VFAs as comparing to PPW-FR-1. At the same time, the pH values of digester PPW-1 and PPW-FR-1 were increased from 7.0 to around 8.0, and the control AD remained at 7.5. The TP levels were found to have no significant difference before and after digestion and