Waste-to-energy: Cellulase induced waste activated sludge and paper waste co-fermentation for efficient volatile fatty acids production and underlying mechanisms

This study mainly investigated the feasibility of utilizing cellulase to enhance waste activated sludge (WAS) and paper waste (PW) co-fermentation for the generation of volatile fatty acids (VFAs). The introduction of cellulase effectively enhanced the co-fermentation efficiency, and the maximum VFAs generation reached 3014 mg COD/L with 60 mg cellulase/g TSS while it was 1512 mg COD/L in the control reactor. The presence of cellulase evidently improved the concentration of soluble bioavailable substrates (e.g., carbohydrates and proteins) via inducing the EPS disintegration and PW disruption. More importantly, the functional anaerobes (i.e., Macellibacteroides and Bacteroides) and the microbial activities (i.e., ATP, key acid-forming enzymes, and genetic expressions) that related with the VFAs biosynthesis were enriched and enhanced due to the stimulation of cellulase, contributing to the ultimate VFAs promotion. This study provided a novel strategy to recover valuable products from waste biomass with constructive mechanistic exploration.

Automated summary

This study found that utilizing cellulase can effectively enhance the co-fermentation efficiency of waste activated sludge and paper waste, increasing the production of volatile fatty acids. The presence of cellulase promotes the concentration of soluble bioavailable substrates, enriches functional anaerobes and microbial activities related to VFAs biosynthesis, ultimately promoting the generation of VFAs.