title: Phosphate Adsorption from Membrane Bioreactor Effluent Using Dowex 21K XLT and Recovery as Struvite and Hydroxyapatite.
abstract: Discharging phosphate through wastewaters into waterways poses a danger to the natural environment due to the serious risks of eutrophication and health of aquatic organisms. However, this phosphate, if economically recovered, can partly overcome the anticipated future scarcity of phosphorus (P) resulting from exhaustion of natural phosphate rock reserves. An experiment was conducted to determine the efficiency of removing phosphate from a membrane bioreactor effluent (pH 7.0-7.5, 20, 35 mg phosphate/L) produced in a water reclamation plant by adsorption onto Dowex 21K XLT ion exchange resin and recover the phosphate as fertilisers. The data satisfactorily fitted to Langmuir adsorption isotherm with a maximum adsorption capacity of 38.6 mg · P/g. The adsorbed phosphate was quantitatively desorbed by leaching the column with 0.1 M NaCl solution. The desorbed phosphate was recovered as struvite when ammonium and magnesium were added at the molar ratio of phosphate, ammonium and magnesium of 1:1:1 at pH 9.5. Phosphate was also recovered from the desorbed solution as hydroxyapatite precipitate by adding calcium hydroxide to the solution at a phosphate to calcium molar ratio of 1:2 at pH 7.0. The P contents of struvite and hydroxyapatite produced were close to those of the respective commercial phosphate fertilisers.
authors.affiliation: Centre for Technology in Water and Wastewater, Faculty of Engineering and Information Technology, University of Technology Sydney, Broadway, Sydney NSW 2007, Australia. Tanjina.Nur@uts.edu.au.
authors.forename: Tanjina
authors.initials: T
authors.lastname: Nur
authors.affiliation: Centre for Technology in Water and Wastewater, Faculty of Engineering and Information Technology, University of Technology Sydney, Broadway, Sydney NSW 2007, Australia. pari.loganathan@yahoo.com.
authors.forename: Paripurnanda
authors.initials: P
authors.lastname: Loganathan
authors.affiliation: Centre for Technology in Water and Wastewater, Faculty of Engineering and Information Technology, University of Technology Sydney, Broadway, Sydney NSW 2007, Australia. jaya.kandasamy@uts.edu.au.
authors.forename: Jaya
authors.initials: J
authors.lastname: Kandasamy
authors.affiliation: Centre for Technology in Water and Wastewater, Faculty of Engineering and Information Technology, University of Technology Sydney, Broadway, Sydney NSW 2007, Australia. s.vigneswaran@uts.edu.au.
authors.forename: Saravanamuthu
authors.initials: S
authors.lastname: Vigneswaran
mesh_terms: D000327:Adsorption; D000818:Animals; D019149:Bioreactors; D002118:Calcium / Q000737:chemistry; D011232:Chemical Precipitation; D017886:Durapatite / Q000737:chemistry; D005068:Eutrophication; D005308:Fertilizers / Q000009:adverse effects; D006801:Humans; D056127:Hydrobiology; D008274:Magnesium / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry / Q000302:isolation & purification; D012117:Resins, Synthetic / Q000737:chemistry; D012995:Solubility; D000069877:Struvite / Q000737:chemistry; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000009:adverse effects / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D005308:Fertilizers; D012117:Resins, Synthetic; D014874:Water Pollutants, Chemical; D010758:Phosphorus; C027972:Dowex; D017886:Durapatite; D000069877:Struvite; D008274:Magnesium; D002118:Calcium
keywords: adsorption; fertiliser; hydroxyapatite; phosphate; struvite; wastewater