A METABOLIC MODEL FOR BIOLOGICAL PHOSPHORUS REMOVAL BY DENITRIFYING ORGANISMS

A metabolic model for biological phosphorus removal under denitrifying conditions has been established. The model is based on previous work with aerobic phosphorus removal. The form of the kinetic equations use d is the same as for the aerobic model. The main difference is the val ue of P/NADH(2) ratio in the electron transport phosphorylation with n itrate (delta(N)). This value was determined independently from batch tests with an enriched culture of denitrifying phosphorus-removing bac teria. The measured delta(N) was approximately 1.0 mol ATP/mol NADH(2) . This indicates that the energy production efficiency with nitrate co mpared to oxygen is approximately 40% lower. These batch tests were al so used to identify a proper set of kinetic parameters. The obtained m odel was subsequently applied for the simulation of cyclic behavior in an anaerobic-anoxic sequencing batch reactor at different biomass ret ention times. The simulation results showed that the metabolic model c an be used successfully for the denitrifying dephosphatation process. The obtained kinetic parameters for denitrifying enrichment cultures, however, deviated from those obtained for the aerobic enrichment cultu res. (C) 1996 John Wiley & Sons, Inc.