title: Precipitation of ammonium from concentrated industrial wastes as struvite: a search for the optimal reagents.
abstract: Precipitation of struvite (MgNH4PO4) is a known process for purification of wastewater from high concentrations of ammonium. The optimal conditions for precipitation are basic pH (around 9) and sufficient concentrations of magnesium and phosphate ions. In this work, we accomplished efficient precipitation of ammonium from concentrated industrial waste stream by using magnesium oxide (MgO) both as a source of magnesium ions and as a base. Best results were obtained with technical-grade MgO, which provided 99% removal of ammonium. Moreover, ammonium removal occurred already at pH 7, and the residual ammonium concentration (50 mg/L) remained constant upon addition of more MgO without rising again, as occurs with sodium hydroxide (NaOH). This process may have two other advantages; it also can be relevant for the problem of uncontrolled precipitation of struvite in the supernatant of anaerobic sludge treatment plants, and the precipitate can be used as a fertilizer.
authors.affiliation: Department of Analytical Chemistry, Nuclear Research Center-Negev, P.O. Box 9001, Be'er Sheva 84190, Israel.
authors.forename: Eitan J C
authors.initials: EJ
authors.lastname: Borojovich
authors.forename: Meshulam
authors.initials: M
authors.lastname: Münster
authors.forename: Gennady
authors.initials: G
authors.lastname: Rafailov
authors.forename: Ze'ev
authors.initials: Z
authors.lastname: Porat
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry; D007202:Indicators and Reagents / Q000737:chemistry*; D007220:Industrial Waste; D017616:Magnesium Compounds / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D000069877:Struvite; D014961:X-Ray Diffraction
chemical_list: D017610:Calcium Compounds; D007202:Indicators and Reagents; D007220:Industrial Waste; D017616:Magnesium Compounds; D010087:Oxides; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D000069877:Struvite; C016538:lime