title: Mitigation of nitrous oxide (N2O) emissions from denitrifying fluidized bed bioreactors (DFBBRs) using calcium.
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.
authors.affiliation: Department 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.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Eldyasti
authors.affiliation: Department of Civil and Environmental Engineering, The University of Western Ontario, London, Ontario N6A 5B9, Canada; Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, Ontario N6A 5B9, Canada. Electronic address: gnakhla@eng.uwo.ca.
authors.forename: George
authors.initials: G
authors.lastname: Nakhla
authors.affiliation: Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, Ontario N6A 5B9, Canada.
authors.forename: Jesse
authors.initials: J
authors.lastname: Zhu
mesh_terms: D019149:Bioreactors; D002118:Calcium / Q000737:chemistry*; D009609:Nitrous Oxide / Q000737:chemistry*
chemical_list: D009609:Nitrous Oxide; D002118:Calcium
keywords: Biofilm; Denitrification; Extracellular polymeric substances (EPS); Fluidized bed bioreactor; Nitrous oxide