Optimization of volatile fatty acids yield in acidogenic phase of anaerobic fermentation of livestock manure

In order to determine the optimum conditions for volatile fatty acids (VFAs) yield in acidogenic phase of anaerobic fermentation of livestock manure, the individual effects and interactive effects of temperature, percentage of pig manure in broth, and initial pH on the VFAs yield were investigated in this study. The experiment results showed that the individual effects and interactive effects of temperature, percentage of pig manure in broth, and initial pH were statistically significant. A quadratic regression equation for VFAs yield was built, and maximum VFAs yield 0.13 g /g VS_resovled was estimated under the optimum conditions for temperature of 35°C, percentage of pig manure in broth of 27.67% and initial pH of 6.93. Under the optimized conditions, the VFAs yield in the latter verification experiment was 0.12 g /g VS_resovled.