Presented at the WEAO 2025 Technical Conference – London, Ontario

As the wastewater industry intensifies its efforts to reduce greenhouse gas (GHG) emissions, understanding nitrous oxide (N₂O) generation in emerging treatment technologies is critical. This study investigates N₂O emissions in a partial denitrification (PDN) process using rope-type fixed-film biofilm media (BioCord® Reactors) developed by Bishop Water.

Conducted in collaboration with Western University, the research involved two bench-scale BioCord reactors operating for 267 days to evaluate the impact of carbon source (acetate vs. methanol), COD/N ratios, and scouring conditions on nitrate removal, nitrite accumulation, and N₂O emissions.

Key findings include:

• Peak nitrite accumulation (60%) was achieved with scouring, higher COD:N ratio (3), and acetate as the carbon source.
• Scouring enhanced biofilm performance, enabling controlled thickness and promoting efficient PDN.
• Higher N₂O emissions occurred under carbon-limited conditions (C/N = 1.5), reaching up to 0.053 g N₂O-N/m²/day, equivalent to 14.44 g CO₂e/m²/day.
• Optimal N₂O mitigation occurred with higher COD/N ratios and reduced biofilm thickness via scouring.

This study is one of the first to systematically examine how operational strategies affect N₂O generation in immobilized biofilm systems designed for nitrogen removal. Results underscore the importance of optimizing reactor conditions for both treatment performance and environmental sustainability.

📄 Download the full paper to explore the experimental design, data analysis, and recommendations for applying PDN in real-world wastewater systems.