Acidogenic fermentation of proteinaceous solid waste and characterization of different bioconversion stages and extracellular products

The purpose of this study was to investigate hydrolysis of animal fleshing (ANFL), a predominant tannery solid waste and to characterize the acetogenic fermentation products of anaerobic digestion. The acidogenic digestibility of the tannery solid wastes were evaluated up to 120 h using batch anaerobic digestion tests performed under mesophilic condition at 37 degrees C. The degradation of ANFL starts with non-fibrillar proteins and proceeds with fibrillar proteins. The release of aliphatic amino acid in the early stages of hydrolysis (24 h) and followed by aromatic amino acids (24-72 h) were evidenced by HPLC analysis. The maximum production of propionic and valeric acid were observed in 72 h followed by rapid increase in acetic acid in 96 h using GC-MS. Breakdown of ANFL and formations of other metabolites were evidenced by FT-IR and (1)H-NMR spectroscopy.