title: Effects of ferrous iron on the performance and microbial community in aerobic granular sludge in relation to nutrient removal.
abstract: Lab-scale experiments were conducted to investigate the effects of ferrous iron on nutrient removal performance and variations in the microbial community inside aerobic granular sludge for 408 days. Two reactors were simultaneously operated, one without added ferrous iron (SBR1), and one with 10 mg Fe2+L-1of added ferrous iron (SBR2). A total of 1 mg Fe2+L-1of added ferrous iron was applied to SBR1 starting from the 191st day to observe the resulting variations in the nutrient removal performance and the microbial community. The results show that ammonia-oxidizing bacteria (AOB) could not oxidize ammonia due to a lack of iron compounds, but they could survive in the aerobic granular sludge. Limited ferrous iron addition encouraged nitrification. Enhanced biological phosphorus removal (EBPR) from both reactors could not be maintained regardless of the amount of ferrous iron that was applied. EBPR was established in both reactors when the concentration of mixed liquor suspended solid (MLSS) and the percentage of Accumulibacteria increased. A total of 10 mg Fe2+L-1of added ferrous iron had a relatively adverse effect on the growth of AOB species compared to 1 mg Fe2+L-1of added ferrous iron, but it encouraged the growth of Nitrospira sp. and Accumulibacteria, which requires further study. It could be said that the compact and stable structure of aerobic granular sludge preserved AOB and NOB from Fe-deficient conditions, and wash-out during the disintegration period. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:716-725, 2017.
authors.affiliation: Department of Environmental Engineering, Istanbul University, Avcilar, Istanbul, 34320, Turkey.
authors.forename: Gulsum
authors.identifier: http://orcid.org/0000-0002-7692-6024
authors.initials: G
authors.lastname: Yilmaz
authors.affiliation: Department of Environmental Engineering, Istanbul University, Avcilar, Istanbul, 34320, Turkey.
authors.forename: Ender
authors.initials: E
authors.lastname: Cetin
authors.affiliation: Department of Environmental Engineering, Istanbul University, Avcilar, Istanbul, 34320, Turkey.
authors.forename: Umit
authors.initials: U
authors.lastname: Bozkurt
authors.affiliation: Department of Environmental Engineering, Istanbul University, Avcilar, Istanbul, 34320, Turkey.
authors.forename: Karin
authors.initials: K
authors.lastname: Aleksanyan Magden
mesh_terms: D000332:Aerobiosis / Q000187:drug effects; D007501:Iron / Q000494:pharmacology*; D058465:Nitrification / Q000187:drug effects; D009584:Nitrogen / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*
chemical_list: D012722:Sewage; D010758:Phosphorus; D007501:Iron; D009584:Nitrogen
keywords: aerobic granular sludge; ferrous iron; microbial community; nitrification; phosphorus removal