Solid-state anaerobic fermentation of spent mushroom compost for volatile fatty acids production by pH regulation

To enhance volatile fatty acid (VFA) production from spent mushroom compost (SMC), the effect of pH from 4.0 to 12.0 was investigated in this study. The results indicated that higher VFA concentration was achieved under alkaline condition compared to acid condition and control. The maximal VFA concentration was 3479.59 mg/L at a pH of 10.0, which was 50.63% higher than the control without pH control. Acetate accounted for more than 50% of total VFAs in all pH values. The NH4+-N and PO43−-P release was in range of 19.56-27.12 mg/g VS and 3.47-15.76 mg/g VS, respectively. Furthermore, the Logistic-based model could well explained the VFA production in this study. Therefore, alkaline fermentation can be considered a promising technology for VFA production from SMC and the optimal pH should be selected as 10.0.