title: Optimization of C/N and current density in a heterotrophic/biofilm-electrode autotrophic denitrification reactor (HAD-BER).
abstract: In this study, central composite design (CCD) and response surface methodology (RSM) were applied to optimize the C/N and current density in a heterotrophic/biofilm-electrode autotrophic denitrification reactor (HAD-BER). Results showed that nitrate could be effectively reduced over a wide range of C/Ns (0.84-1.3535) and current densities (96.8-370.0 mA/m(2)); however, an optimum C/N of 1.13 and optimum current density of 239.6 mA/m(2) were obtained by RSM. Moreover, the HAD-BER performance under the optimum conditions resulted in almost 100% nitrate-N removal efficiency and low nitrite-N and ammonia-N accumulation. Furthermore, under the optimum conditions, H2 generated from water electrolysis matched the CO2 produced by heterotrophic denitrification by stoichiometric calculation. Therefore, CCD and RSM could be used to acquire optimum operational conditions and improve the nitrate removal efficiency and energy consumption in the HAD-BER.
authors.affiliation: Key Laboratory of Groundwater Circulation and Evolution (China University of Geosciences Beijing), Ministry of Education, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Tong
authors.affiliation: Key Laboratory of Groundwater Circulation and Evolution (China University of Geosciences Beijing), Ministry of Education, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Chen
authors.affiliation: School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China.
authors.forename: Heng
authors.initials: H
authors.lastname: Wang
authors.affiliation: School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China.
authors.forename: Hengyuan
authors.initials: H
authors.lastname: Liu
authors.affiliation: School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Tao
authors.affiliation: Key Laboratory of Groundwater Circulation and Evolution (China University of Geosciences Beijing), Ministry of Education, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China. Electronic address: fengchuanping@gmail.com.
authors.forename: Chuanping
authors.initials: C
authors.lastname: Feng
authors.affiliation: School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China.
authors.forename: Baogang
authors.initials: B
authors.lastname: Zhang
authors.affiliation: School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China.
authors.forename: Chunbo
authors.initials: C
authors.lastname: Hao
authors.affiliation: School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China.
authors.forename: Jiaoyang
authors.initials: J
authors.lastname: Pu
authors.affiliation: School of Water Resources and Environment, China University of Geosciences Beijing, Beijing 100083, China.
authors.forename: Jiamin
authors.initials: J
authors.lastname: Zhao
mesh_terms: D000704:Analysis of Variance; D001419:Bacteria / Q000378:metabolism*; D018441:Biofilms; D019149:Bioreactors; D002244:Carbon / Q000032:analysis; D002245:Carbon Dioxide / Q000378:metabolism; D058440:Denitrification / Q000502:physiology*; D004572:Electrolysis; D060587:Groundwater / Q000737:chemistry*; D052836:Heterotrophic Processes / Q000502:physiology; D006859:Hydrogen / Q000302:isolation & purification; D009566:Nitrates / Q000378:metabolism*; D009584:Nitrogen / Q000032:analysis; D012722:Sewage / Q000382:microbiology; D013056:Spectrophotometry, Ultraviolet; D018508:Water Purification / Q000379:methods*
chemical_list: D009566:Nitrates; D012722:Sewage; D002245:Carbon Dioxide; D002244:Carbon; D006859:Hydrogen; D009584:Nitrogen
keywords: Central composite design (CCD); HAD-BER; Nitrate reduction; Optimization; Response surface methodology (RSM)