No abstract

No abstract

The application of a general model for nitrification denitrification biological excess phosphorus removal (NDBEPR) activated‐sludge systems is demonstrated. Results of simulations show the model is capable of predicting sludge production and oxygen use for a range of system types and configurations, and of tracking changes in a number of parameters including soluble phosphorus and nitrate concentrations. Application of the model is demonstrated for aerobic and anoxic–aerobic systems and for a number of nutrient removal systems for both steady‐state and for dynamic conditions.

Results of model simulations indicate that without the assumption of COD loss, predictions of oxygen consumption and volatile suspended solids production are significantly over-estimated for biological excess phosphorus removal (BEPR) activated sludge systems (and to a lesser extent anoxic-aerobic systems). These systems apparently consume less oxygen and produce less volatile solids than aerobic systems for the same amount of COD removal. A general model for biological nutrient removal systems has recently been presented by Barker and Dold. Three mechanisms for COD loss are suggested, based on results of COD balances for different types of activated sludge system. Model simulation results with and without the assumption of COD loss are discussed, as well as the influence of influent COD composition on predictions of volatile suspended solids concentration/production and oxygen consumption.