title: Basic Oxygen Furnace steel slag aggregates for phosphorus treatment. Evaluation of its potential use as a substrate in constructed wetlands.
abstract: Basic Oxygen Furnace (BOF) steel slag aggregates from NW Spain were tested in batch and column experiments to evaluate its potential use as a substrate in constructed wetlands (CWs). The objectives of this study were to identify the main P removal mechanisms of BOF steel slag and determine its P removal capacity. Also, the results were used to discuss the suitability of this material as a substrate to be used in CWs. Batch experiments with BOF slag aggregates and increasing initial phosphate concentrations showed phosphate removal efficiencies between 84 and 99% and phosphate removal capacities from 0.12 to 8.78 mg P/g slag. A continuous flow column experiment filled with BOF slag aggregates receiving an influent synthetic solution of 15 mg P/L during 213 days showed a removal efficiency greater than 99% and a phosphate removal capacity of 3.1 mg P/g slag. In both experiments the main P removal mechanism was found to be calcium phosphate precipitation which depends on Ca(2+) and OH(-) release from the BOF steel slag after dissolution of Ca(OH)2 in water. P saturation of slag was reached within the upper sections of the column which showed phosphate removal capacities between 1.7 and 2.5 mg P/g slag. Once Ca(OH)2 was completely dissolved in these column sections, removal efficiencies declined gradually from 99% until reaching stable outlet concentrations with P removal efficiencies around 7% which depended on influent Ca(2+) for limited continuous calcium phosphate precipitation.
authors.affiliation: Instituto de Medio ambiente, Recursos Naturales y Biodiversidad, Universidad de León, Calle La Serna, nº 56, 24071, León, Spain. Electronic address: ivan.blanco@unileon.es.
authors.forename: Ivan
authors.initials: I
authors.lastname: Blanco
authors.affiliation: Wastewater Treatment Team, Freshwater System, Ecology and Pollution Research Unit, Irstea, 5 rue de la Doua, CS70077, 69626, Villeurbanne Cedex, France. Electronic address: pascal.molle@irstea.fr.
authors.forename: Pascal
authors.initials: P
authors.lastname: Molle
authors.affiliation: Departamento de Biología Molecular, Universidad de León, Campus de Vegazana s/n, 24071, León, Spain. Electronic address: luis.saenzdemiera@unileon.es.
authors.forename: Luis E
authors.initials: LE
authors.lastname: Sáenz de Miera
authors.affiliation: Departamento de Biodiversidad y Gestión Ambiental, Universidad de León, Campus de Vegazana s/n, CP: 24071, León, Spain. Electronic address: gemma.ansola@unileon.es.
authors.forename: Gemma
authors.initials: G
authors.lastname: Ansola
mesh_terms: D002118:Calcium / Q000737:chemistry; D007220:Industrial Waste; D010758:Phosphorus / Q000737:chemistry*; D013030:Spain; D013232:Steel; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D053833:Wetlands
chemical_list: D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D013232:Steel; D010758:Phosphorus; D002118:Calcium
keywords: Batch experiment; Column experiment; Constructed wetland; Phosphorus; Steel slag