Upgrading volatile fatty acids production through anaerobic co-fermentation of mushroom residue and sewage sludge: Performance evaluation and kinetic analysis
Résumé
Due to complex inherent structure of lignocellulosic biomass, inefficient hydrolysis and acidification limits
fermentative volatile fatty acids (VFA) production of mushroom residues. Meanwhile, the mushroom residues
present insufficient nutrient with a high C/N ratio. To solve this issue, anaerobic co-fermentation of celluloserich Oyster champost and sewage sludge was tested to enhance the VFA production, and the effect of proportion
of mixed substrate was investigated in this study. The results indicated that the sewage sludge yielded higher
VFAs than the Oyster champost in single-substrate fermentative system. The maximal VFA yield of 595 mgCOD/
gVSadded was achieved when the proportion of sewage sludge increased to 50% in the mixed substrate. In the cofermentation system, the optimal C/N ratio and features of mixed substrate contributed to the enhancement in
hydrolysis and acidification in terms of organic solubilization and VFA production, respectively. But the cofermentation could not increase VFA/SCOD ratio, probably due to the existence of refractory products such as
humic-like and protein-like materials. Besides, this co-fermentation system had strong buffer capacity and it was
not necessary to dose chemicals to control the system pH for stable VFA production. Acetate was the dominant
VFA product in co-fermentation systems. A modified-Logistic model fitted co-fermentation of sludge and Oyster
champost well, and presented a faster rate and higher efficiency of VFA production
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