Volatile fatty acid production from spent mushroom compost: Effect of total solid content

To improve volatile fatty acids (VFAs) production from spent mushroom compost (SMC), the effect of total solid (TS) content was studied. The protein and polysaccharide solubilization, ammonium (NH4+-N) and phosphate (PO43−-P) release, and VFAs production were analyzed. Results showed that the optimal fermentation time was 4 day for VFAs production, longer fermentation time led to VFAs consumption and methane production. Within the TS range from 6% to 18%, a TS of 15% was the optimal for VFAs production, the highest VFAs concentration reached 2781 mg/L, and acetate and propionate acids accounted for about 71% of total VFAs. In addition, the maximum concentration of soluble protein and polysaccharide reached approximately 1648 mg/L and 1394 mg/L, respectively. The NH4+-N and PO43−-P release was in a range of 2.11-7.59 mg/gVS and 0.26-1.13 mg/gVS, respectively. If the NH4+-N and PO43−-P can be removed, the application of VFAs utilization might be significantly enhanced.