Phosphorus Retention Mechanisms of a Water Treatment Residual
- 1 September 2003
- journal article
- Published by Wiley in Journal of Environmental Quality
- Vol. 32 (5), 1857-1864
- https://doi.org/10.2134/jeq2003.1857
Abstract
Water treatment residuals (WTRs) are a by-product of municipal drinking water treatment plants and can have the capacity to adsorb tremendous amounts of P. Understanding the WTR phosphorus adsorption process is important for discerning the mechanism and tenacity of P retention. We studied P adsorbing mechanism(s) of an aluminum-based [Al2(SO4)3·14H2O] WTR from Englewood, CO. In a laboratory study, we shook mixtures of P-loaded WTR for 1 to 211 d followed by solution pH analysis, and solution Ca, Al, and P analysis via inductively coupled plasma atomic emission spectroscopy. After shaking periods, we also examined the solids fraction by X-ray diffraction (XRD) and electron microprobe analysis using wavelength dispersive spectroscopy (EMPA–WDS). The shaking results indicated an increase in pH from 7.2 to 8.2, an increase in desorbed Ca and Al concentrations, and a decrease in desorbed P concentration. The pH and desorbed Ca concentration increases suggested that CaCO3 controlled Ca solubility. Increased desorbed Al concentration may have been due to Al OH − 4 formation. Decreased P content, in conjunction with the pH increase, was consistent with calcium phosphate formation or precipitation. The system appeared to be undersaturated with respect to dicalcium phosphate (DCP; CaHPO4) and supersaturated with respect to octacalcium phosphate [OCP; Ca4H(PO4)3·2.5H2O]. The Ca and Al increases, as well as OCP formation, were supported by MINTEQA2 modeling. The XRD and EMPA–WDS results for all shaking times, however, suggested surface P chemisorption as an amorphous Al–P mineral phase. Copyright © 2003. American Society of Agronomy, Crop Science Society of America, Soil Science Society . ASA, CSSA, SSSAKeywords
This publication has 37 references indexed in Scilit:
- Co‐Application Effects of Water Treatment Residuals and Biosolids on Two Range GrassesJournal of Environmental Quality, 1999
- Phosphate sorption by calcareous Vertisols and Inceptisols as evaluated from extended P‐sorption curvesEuropean Journal of Soil Science, 1998
- Phosphate Mineralogy and Equilibria in Two Kentucky Alfisols Derived from Ordovician LimestonesSoil Science Society of America Journal, 1991
- Phosphorus Chemistry and Mineralogy in Excessively Fertilized Soils: Solubility EquilibriaSoil Science Society of America Journal, 1990
- Phosphorus Chemistry and Mineralogy in Excessively Fertilized Soils: Quantitative Analysis of Phosphorus‐rich ParticlesSoil Science Society of America Journal, 1990
- Phosphorus Chemistry and Mineralogy in Excessively Fertilized Soils: Descriptions of Phosphorus‐rich ParticlesSoil Science Society of America Journal, 1990
- Effect of water treatment sludge on growth and elemental composition of tomato (Lycopersicon esculentum) shootsCommunications in Soil Science and Plant Analysis, 1988
- Residual Available Phosphorus in Near-Neutral and Alkaline Soils: I. Solubility and Capacity RelationshipsSoil Science Society of America Journal, 1982
- The Interaction of Phosphate with CalciteSoil Science Society of America Journal, 1973
- Electron Microprobe Analysis of Phosphates in Soils and SedimentsSoil Science Society of America Journal, 1973