Further contributions to nitrogen removal modelling in waste stabilization ponds

Area of Science:

• Environmental Engineering
• Wastewater Treatment
• Aquatic Ecosystems

Background:

• Facultative and maturation ponds are crucial for wastewater treatment, particularly for nitrogen removal.
• Accurate modeling of ammonium and total nitrogen (TN) removal is essential for efficient pond design and operation.
• Existing models require validation against real-world data to assess their predictive capabilities.

Purpose of the Study:

• To verify the agreement between field results and predictions from widely accepted models for ammonium and TN removal in ponds.
• To develop a new, pH-independent linear model for predicting ammonium removal based on surface loading rates.
• To evaluate the performance of existing models in predicting varying effluent concentrations.

Main Methods:

• Utilized a large database from an experimental maturation pond system in Brazil.
• Compared field data with predictions from established ammonium and TN removal models.
• Derived a new linear model for ammonium removal, focusing on pH independence and surface loading rate.

Main Results:

• Most widely accepted models provided reasonable predictions for ammonium and TN removal.
• Models tended to overestimate low ammonium effluent concentrations and underestimate higher values.
• The newly derived pH-independent model demonstrated that ammonium removal is primarily a function of the ammonium surface loading rate.

Conclusions:

• Existing models offer a useful, though imperfect, tool for predicting nitrogen removal in ponds.
• The developed pH-independent model offers a simpler, effective alternative for predicting ammonium removal based on loading rates.
• Further refinement of models is needed to improve accuracy across the full range of effluent concentrations.