title: Effects of hydraulic retention time and [Formula: see text] ratio on thiosulfate-driven autotrophic denitrification for nitrate removal from micro-polluted surface water.
abstract: This study was carried out to investigate the possibility of a thiosulfate-driven autotrophic denitrification for nitrate-N removal from micro-polluted surface water. The aim was to study the effects of [Formula: see text] ratio (S/N molar ratio) and hydraulic retention time (HRT) on the autotrophic denitrification performance. Besides, utilization efficiencies of [Formula: see text] along the biofilter and the restart-up of the bioreactor were also investigated. Autotrophic denitrification using thiosulfate as an electron donor for treating micro-polluted surface water without the addition of external alkalinity proved to be feasible and the biofilter could be readied in two weeks. Average nitrate-N removal efficiencies at HRTs of 0.5, 1 and 2 h were 78.7%, 87.8% and 97.4%, respectively, and corresponding removal rates were 186.24, 103.92 and 58.56 g [Formula: see text], respectively. When water temperature was in the range of 8-12°C and HRT was 1 h, average nitrate-N removal efficiencies of 41.9%, 97.1% and 97.0%, nitrite accumulation concentrations of 1.45, 0.46 and 0.22 mg/L and thiosulfate utilization efficiencies of 100%, 98.8% and 92.1% were obtained at S/N ratios of 1.0, 1.2 and 1.5, respectively. Besides, the autotrophic denitrification rate in the filtration media layer was the highest along the biofilter at an S/N ratio of 1.5. Finally, after a one-month period of starvation, the biofilter could be restarted successfully in three weeks without inoculation of seed sludge.
authors.affiliation: a School of Environmental Science and Engineering , Shanghai Jiaotong University , Shanghai , People's Republic of China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.affiliation: a School of Environmental Science and Engineering , Shanghai Jiaotong University , Shanghai , People's Republic of China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Fei
authors.affiliation: a School of Environmental Science and Engineering , Shanghai Jiaotong University , Shanghai , People's Republic of China.
authors.forename: Sheng-Bing
authors.initials: SB
authors.lastname: He
authors.affiliation: a School of Environmental Science and Engineering , Shanghai Jiaotong University , Shanghai , People's Republic of China.
authors.forename: Jung-Chen
authors.initials: JC
authors.lastname: Huang
authors.affiliation: a School of Environmental Science and Engineering , Shanghai Jiaotong University , Shanghai , People's Republic of China.
authors.forename: Wei-Li
authors.initials: WL
authors.lastname: Zhou
mesh_terms: D052818:Autotrophic Processes; D019149:Bioreactors; D058440:Denitrification; D005374:Filtration; D009566:Nitrates / Q000378:metabolism*; D013885:Thiosulfates / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D009566:Nitrates; D013885:Thiosulfates; D014874:Water Pollutants, Chemical
keywords: Nitrate removal; biofilter; micro-polluted surface water; removal efficiency; thiosulfate-driven autotrophic denitrification