Influence of fermentation metabolites on redox potential in anaerobic digestion of proteinaceous solid wastes by Synergistes sp

The anaerobic digestion of animal fleshing from tannery solid waste was investigated with regard to hydrolytic enzymes, protease and lipase, fermentative enzyme deaminase, soluble protein and amino acids, redox potential (Eh), volatile fatty acids, ammonia and carbon dioxide up to 120 h of retention time. The release of these fermentation metabolites at various retention times greatly influenced the Eh. In the hydrolytic phase, the maximum value of Eh was −50 mV and it reached the minimum of −350 mV in 24 h in the fermentative phase. The minimum and maximum values of Eh were −387 and −452 mV at 80 h of anaerobic digestion. The release of extracellular metabolites was confirmed by HPLC and GC‐MS. In this study, we have found that the ammonia and pH had a substantial influence on the Eh during the anaerobic digestion of animal fleshing.