Model of the anaerobic metabolism of the biological phosphorus removal process: Stoichiometry and pH influence

TLDR

In anaerobic biological phosphorus removal, acetate is converted to poly‑β‑hydroxybutyrate using energy from polyphosphate degradation and glycogen conversion, and the phosphate/acetate ratio varies with pH. The study develops a structured metabolic model to describe the anaerobic phase of phosphorus removal. The model assumes glycogen supplies the reduction equivalents and incorporates the pH‑dependent energy requirement for acetate uptake. The model reproduces the experimental phosphate/acetate ratio variation of 0.25–0.75 P‑mol/C‑mol across pH 5.5–8.5 and shows that glycogen provides the necessary reduction equivalents and energy for acetate conversion to PHB. © 1994 John Wiley & Sons, Inc.

Abstract

In the anaerobic phase of a biological phosphorus removal process, acetate is taken up and converted to PHB utilizing both energy generated in the degradation of polyphosphate to phosphate, which is released, and energy generated in the conversion of glycogen to poly-beta-hydroxy butyrate (PHB). The phosphate/acetate ratio cannot be considered a metabolic constant, because the energy requirement for the uptake of acetate is strongly influenced by the pH value. The observed phosphate/acetate ratio shows a variation of 0.25 to 0.75 P-mol/C-mol in a pH range of 5.5 to 8.5. It is shown that stored glycogen takes part in the metabolism to provide reduction equivalents and energy for the conversion of acetate to PHB. A structured metabolic model, based on glycogen as the source of the reduction equivalents in the anaerobic phase and the effect of the pH on the energy requirement of the uptake of acetate, is developed. The model explains the experimental results satisfactorily. (c) 1994 John Wiley & Sons, Inc.