ARTICLE
BioCord® Reactors demonstrate partial denitrification process and mitigation of nitrous oxide emissions
New research sheds light on the optimized conditions for BioCord Reactors to achieve partial denitrification (PDN) for nitrite accumulation while significantly reducing emission of nitrous oxide (N20), a potent greenhouse gas. BioCord Reactors are a semi-passive, rope-type biofilm system that can cost-effectively enhance nitrogen removal even in cold temperatures.
The research was presented at the 2025 WEAO Technical Symposium by Dr. Wudneh Shewa, Bishop Water’s Technical Solutions and Project Manager.
Partial denitrification is an important step for wastewater treatment plants that are designed for total nitrogen removal using the anammox process. However, during denitrification, denitrifying bacteria convert nitrate (NO3) into nitrogen gas (N2), with nitrous oxide (N2O) released as a byproduct.
Industry-leading research
To date, little research has been conducted to understand N20 emissions from co-diffusion biofilm-based nitrogen removal technologies such as BioCord Reactors. The research, which was conducted at the Biofilm Engineering and Wastewater Resource Recovery Laboratory (BEWRR) of Western University (London, ON), provides an in-depth study and evaluates several approaches to mitigate N20 emissions.
The comprehensive study examined several factors to determine the impact on nitrite accumulation and N2O emission including varying chemical oxygen demand to nitrogen ratios (COD:N), carbon sources, hydraulic retention times and scouring vs. non-scouring modes.
By using acetate as the carbon source, maintaining a COD:N ratio of 3, and incorporating biofilm scouring, researchers achieved the best balance of nitrite accumulation and minimal N2O production.
After increasing COD:N from 1.5 to 3, the BioCord Reactor system experienced an increase in NO3 removal and NO2 accumulation and a significant reduction in N2O emission.
The findings underscored the necessity of balancing carbon source selection and operational parameters to optimize PDN performance, reduce GHG emissions, and maximize nitrite accumulation in biofilm-based systems. This study lays the groundwork for advancing sustainable nitrogen management strategies in wastewater treatment.
We are grateful to Dr. Martha Dagnew at the Biofilm Engineering and Wastewater Resource Recovery Laboratory (BEWRR) of Western University (London, ON) and Dr. Lin Sun for conducting all the experiments and required wastewater and off-gas analyses. This research was financially funded by Mitacs and the Ontario Water Consortium’s Water Industry Growth Program (WIG).
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