RETRACTED: Stoichiometry of Anaerobic Protein Fermentation

Abstract

Abstract The stoichiometric reactions that characterize protein fermentation during anaerobic wastewater treatment were investigated using bovine serum albumin (BSA) as the model protein. A methodology was developed to describe anaerobic protein degradation to volatile fatty acids (VFAs) using a single reaction step based on the dominant amino acid fermentation pathways. The importance of this work stems from the burgeoning need for resource recovery by production of VFAs from waste activated sludge at municipal wastewater treatment plants. The optimum initial fermentation conditions for BSA degradation to organic acids were first established at a pH of 8 and fermentation time of 3 days. The results from two batch experiments of BSA at concentrations of 2 g/L and 4 g/L showed that the stoichiometric coefficients for acetic, butyric, and valeric acids generally compared very well with the theoretical except for propionic acid which resulted from an alternative fermentation pathway for arginine and proline without propionic acid production. The organic acids produced at each BSA concentration varied respectively by ± 15 % and ± 12 % from the theoretical and the amino acid fermentation pathways remained the same irrespective of concentration differences. The experimental stoichiometric coefficients for iso-butyric and iso-valeric acids were within 10%–15% of the theoretical values, thus validating the use of a single stoichiometry for the overall catabolic reaction of anaerobic protein fermentation to organic acids.