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Updated: Apr 22, 2026

Estimating Sediment Denitrification Rates Using Cores and N2O Microsensors
Published on: December 6, 2018
Mitigation of nitrous oxide (N2O) emissions from denitrifying fluidized bed bioreactors (DFBBRs) using calcium
Ahmed Eldyasti1, George Nakhla2, Jesse Zhu3
1Department of Civil Engineering, Lassonde School of Engineering, York University, Toronto, Ontario M3J 1P3, Canada; Department of Civil and Environmental Engineering, The University of Western Ontario, London, Ontario N6A 5B9, Canada.
Abstract:
Nitrous oxide (N2O) is a significant anthropogenic greenhouse gases (AnGHGs) emitted from biological nutrient removal (BNR) processes. In this study, N2O production from denitrifying fluidized bed bioreactors (DFBBR) was reduced using calcium (Ca2+) dosage. The DFBBRs were operated on a synthetic municipal wastewater at four different calcium concentrations ranging from the typical municipal wastewater Ca2+ concentration (60 mg Ca2+/L) to 240 mg Ca2+/L at two different COD/N ratios. N2O emission rates, extracellular polymeric substances (EPS), water quality parameters, and microscopic images were monitored regularly in both phases. Calcium concentrations played a significant role in biofilm morphology with the detachment rates for R120Ca, R180Ca, and R240Ca 75% lower than for R60Ca, respectively. The N2O conversion rate at the typical municipal wastewater Ca2+ concentration (R60Ca) was about 0.53% of the influent nitrogen loading as compared with 0.34%, 0.42%, and 0.41% for R120Ca, R180Ca, and R240Ca, respectively corresponding to 21-36% reduction.
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