Dynamic Nutrient Cycle for Waste Stabilization Ponds

Stabilization ponds provide a simple, economic, and effective method of waste treatment. There is a critical need for a reliable, predictive method for the design and analysis of stabilization ponds that goes beyond the steady state BOD approach and considers biological and nutrient dynamics. A fully-mixed, dynamic model containing eight state variables and describing the transformations of three elements—carbon, nitrogen, and phosphorus—is developed. The model reflects the cycling of elements between organic and inorganic forms and is capable of predicting oxygen demand, fecal coliform, nitrogen, and phosphorus concentrations on a time-variable basis. The model structure adequately simulates the stabilization pond environment. Calibration and verification runs have established values and ranges for the rate coefficients.