Total-solids-controlled microbial response and volatile fatty acids production in sludge and chicken manure co-fermentation.

With the aim of exploring the association between microbial response and volatile fatty acids (VFAs) production in sludge and chicken manure co-fermentation with total solids (TS) controlled, four fermentation experimental groups (TS = 20, 40, 60, and 80 g/L) were established in this study. The results demonstrated that the yield of VFAs reached the peak (530.08 mg COD/g VSS) at the 40 g-TS group. For microbial characteristics, Firmicutes, Bacteroidota, Spirochaetota, and Proteobacteria were the main dominant phyla in each experimental group. Meanwhile, it could be proven that the enrichment of functional strains had a significant effect on the production and accumulation of VFAs at the 40 g-TS group through α analysis and microbial community structure analysis. In addition, Bacteroidota was predicted to be the main producer of VFAs in the experimental co-fermentation systems through the Faprotax function prediction. This study revealed the effects of different TS concentrations on microbial communities in sludge and chicken manure co-fermentation, and investigated the relationship between microbial community and VFAs production.