XANES speciation of P in environmental samples: an assessment of filter media for on-site wastewater treatment.
X-ray absorption near edge structure (XANES) spectroscopy is a useful technique for characterization of chemical species of phosphorus in complex environmental samples. To develop and evaluate bed filters as sustainable on-site wastewater treatment solutions, our objective in this study was to determine the chemical forms of accumulated phosphorus in a selection of promising filter materials: Filtralite P, Filtra P, Polonite, Absol, blast furnace slag, and wollastonite. Full-scale operational wastewater-treatment systems were sampled and in addition, filter samples collected from laboratory studies provided access to additional media and complementary samples. Phosphorus species were characterized using phosphorus K-edge XANES spectroscopy, complemented by X-ray powder diffraction (XRPD) and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). No systematic differences could be seen in the results between laboratory- and full-scale samples. All six filter media contained significant amounts of crystalline calcium phosphates. Some samples also contained amorphous calcium phosphate (>60% of total P in Absol). In Filtralite P and blast furnace slag, more than 35% of the accumulated phosphorus was associated with Fe or Al. Both the power and shortcomings of XANES analysis for characterizing P species in these filter media are discussed.
Eveborn
David
D
Department of Land and Water Resources Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden. eveborn@kth.se
Gustafsson
Ion Petter
IP
Hesterberg
Dean
D
Hillier
Stephen
S
D005374:Filtration / Q000295:instrumentation; D010758:Phosphorus / Q000032:analysis*; D012015:Reference Standards; D017550:Spectroscopy, Fourier Transform Infrared; D013057:Spectrum Analysis / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D014961:X-Ray Diffraction; D014965:X-Rays
D014874:Water Pollutants, Chemical; D010758:Phosphorus