title: Heterotrophic-autotrophic sequential system for reductive nitrate and perchlorate removal.
abstract: Nitrate and perchlorate were identified as significant water contaminants all over the world. This study aims at evaluating the performances of the heterotrophic-autotrophic sequential denitrification process for reductive nitrate and perchlorate removal from drinking water. The reduced nitrate concentration in the heterotrophic reactor increased with increasing methanol concentrations and the remaining nitrate/nitrite was further removed in the following autotrophic denitrifying process. The performances of the sequential process were studied under varying nitrate loads of [Formula: see text] at a fixed hydraulic retention time of 2 h. The C/N ratio in the heterotrophic reactor varied between 1.24 and 2.77 throughout the study. Nitrate and perchlorate reduced completely with maximum initial concentrations of [Formula: see text] and 1000 µg/L, respectively. The maximum denitrification rate for the heterotrophic reactor was [Formula: see text] when the bioreactor was fed with [Formula: see text] and 277 mg/L methanol. For the autotrophic reactor, the highest denitrification rate was [Formula: see text] in the first period when the heterotrophic reactor performance was low. Perchlorate reduction was initiated in the heterotrophic reactor, but completed in the following autotrophic process. Effluent sulphate concentration was below the drinking water standard level of 250 mg/L and pH was in the neutral level.
authors.affiliation: a Environmental Engineering Department , Faculty of Civil Engineering, Istanbul Technical University , Maslak, Istanbul 34469 , Turkey.|b Environmental Engineering Department , Faculty of Engineering, Harran University , Sanlıurfa 63100 , Turkey.
authors.forename: Deniz
authors.initials: D
authors.lastname: Ucar
authors.affiliation: a Environmental Engineering Department , Faculty of Civil Engineering, Istanbul Technical University , Maslak, Istanbul 34469 , Turkey.
authors.forename: Emine Ubay
authors.initials: EU
authors.lastname: Cokgor
authors.affiliation: c Bioengineering Department , Faculty of Engineering and Architecture, Istanbul Medeniyet University , Goztepe, Istanbul 34730 , Turkey.
authors.forename: Erkan
authors.initials: E
authors.lastname: Sahinkaya
mesh_terms: D052818:Autotrophic Processes; D019149:Bioreactors; D058440:Denitrification; D060766:Drinking Water / Q000032:analysis*; D052836:Heterotrophic Processes; D009566:Nitrates / Q000378:metabolism*; D010084:Oxidation-Reduction; D010472:Perchlorates / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D018508:Water Purification / Q000379:methods*
chemical_list: D060766:Drinking Water; D009566:Nitrates; D010472:Perchlorates; D014874:Water Pollutants, Chemical; C494474:perchlorate
keywords: elemental sulphur; heterotrophic process; nitrate reduction; perchlorate reduction; sequential system