title: Phosphorus removal performance and speciation in virgin and modified argon oxygen decarburisation slag designed for wastewater treatment.
abstract: Argon oxygen decarburisation (AOD) slag may be used for phosphorus (P) removal, as its high pH and weatherable calcium (Ca) minerals provide sufficient Ca(2+) and OH(-) for calcium phosphate (Ca-PO4) precipitation. This study examined the P removal performance of AOD slag for use as wastewater treatment material. Batch experiments were carried out using both synthetic P solution and real wastewater, followed by chemical modelling and X-ray absorption near edge structure (XANES) spectroscopy. The influences of initial P concentration, slag dose and modification by polyethylene glycol (PEG), an effective agent for generation of porous materials, were investigated to determine the optimal conditions for P removal by AOD slag. It was found that virgin AOD slag removed 94.8% of P from a synthetic P solution in 4 h and 97.8% in 10 h. This high P removal was accompanied by a rapid increase in pH from 7.0 to 10.74. The maximum P removal capacity (PRC) from synthetic P solution ranged from 1.3 to 27.5 mg P g(-1). The optimal AOD dose for P removal from wastewater, determined in 8-h batch experiments, was 25 g L(-1). PEG modification increased the reaction rate and resulted in higher final pH, increasing PRC by 47.9%. Combined Visual MINTEQ and XANES analysis for detailed examination of P removal mechanisms revealed that the main P removal mechanism was precipitation of calcium phosphate. According to the XANES analysis, the main Ca-PO4 precipitate formed on virgin AOD slag under low initial P concentration and high pH was apatite, while brushite was the dominant product at high initial P concentration and low pH.
authors.affiliation: Division of Land and Water Resources Engineering, KTH Royal Institute of Technology, Teknikringen 76, SE-100 44 Stockholm, Sweden. Electronic address: minyu@kth.se.
authors.forename: Minyu
authors.initials: M
authors.lastname: Zuo
authors.affiliation: Division of Land and Water Resources Engineering, KTH Royal Institute of Technology, Teknikringen 76, SE-100 44 Stockholm, Sweden. Electronic address: gunno@kth.se.
authors.forename: Gunno
authors.initials: G
authors.lastname: Renman
authors.affiliation: Division of Land and Water Resources Engineering, KTH Royal Institute of Technology, Teknikringen 76, SE-100 44 Stockholm, Sweden; Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, SE-750 07 Uppsala, Sweden. Electronic address: gustafjp@kth.se.
authors.forename: Jon Petter
authors.initials: JP
authors.lastname: Gustafsson
authors.affiliation: Division of Land and Water Resources Engineering, KTH Royal Institute of Technology, Teknikringen 76, SE-100 44 Stockholm, Sweden. Electronic address: agak@kth.se.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Renman
mesh_terms: D001128:Argon / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D010758:Phosphorus / Q000032:analysis*; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D001128:Argon; D010100:Oxygen; D010758:Phosphorus; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Apatite; Brushite; Phosphorus; Slag; Visual MINTEQ; XANES