The Sensitivity of a Specific Denitrification Rate under the Dissolved Oxygen Pressure

Area of Science:

• Environmental Engineering
• Microbiology
• Water Treatment

Background:

• Biological denitrification is vital for nitrogen removal in wastewater treatment.
• Anoxic conditions are necessary, but the effect of residual dissolved oxygen (DO) on efficiency remains unclear.
• Specific denitrification rate at 20°C (SDNR20°C) is key for reactor design.

Purpose of the Study:

• To investigate the impact of dissolved oxygen (DO) on the specific denitrification rate (SDNR).
• To analyze the sensitivity of SDNR20°C to DO variations using established and novel models.
• To provide insights for optimizing denitrification processes in full-scale plants.

Main Methods:

• Sensitivity analysis of SDNR20°C to DO variations.
• Utilized two empirical models from literature and a new deterministic model.
• Validated the deterministic model with full-scale plant data.

Main Results:

• SDNR20°C exhibits a significant logarithmic decrease with increasing DO, particularly pronounced at low concentrations.
• The food-to-microorganism ratio (F:M) has a minor influence on SDNR20°C and its relationship with DO.
• Low DO levels are critical for maintaining high denitrification efficiency.

Conclusions:

• Minimizing DO in denitrification reactors is essential for process efficiency.
• Limiting oxygen transport via influent and mixed liquor recycle is recommended.
• The findings support strategies for enhancing nitrogen removal in biological treatment systems.