Effects of Redox Potential and pH Changes on Phosphorus Retention by Melter Slag Filters Treating Wastewater

Pratt, C., Shilton, A., Pratt, S., Haverkamp, R. G. and Elmetri, I. (2007) Effects of Redox Potential and pH Changes on Phosphorus Retention by Melter Slag Filters Treating Wastewater. Environmental Science and Technology, 41 18: 6585-6590. doi:10.1021/es070914m


Author Pratt, C.
Shilton, A.
Pratt, S.
Haverkamp, R. G.
Elmetri, I.
Title Effects of Redox Potential and pH Changes on Phosphorus Retention by Melter Slag Filters Treating Wastewater
Journal name Environmental Science and Technology   Check publisher's open access policy
ISSN 0013-936X
Publication date 2007-08-17
Sub-type Article (original research)
DOI 10.1021/es070914m
Volume 41
Issue 18
Start page 6585
End page 6590
Total pages 6
Editor Jerald Schnoor
Place of publication Washington, D.C.
Publisher American Chemical Society
Language eng
Subject 090409 Wastewater Treatment Processes
Abstract The release of phosphorus (P) and iron (Fe) from a melter slag filter in solutions of varying Eh and pH was examined. The filter had been removing P from waste stabilization pond effluent for several years. The study revealed that the highest P (95% of total P) and Fe (25% of total Fe) release from the slag occurred in the solution with the lowest Eh (−400 mV, relative to the standard hydrogen electrode, SHE) and lowest pH (4.9). Solutions with high pH (9.1) also proved favorable for P release (20 to 40% of total P) from the slag, at both reducing (−400 mV) and oxidizing (+300 mV) Eh. By contrast, solutions with pH 4.9 and 6.7 and oxidizing Eh (+300 mV) liberated the lowest P and Fe contents into the aqueous phase (<1% for both elements). The findings showed that Eh and pH are important parameters affecting P release from slag filters. At low Eh and low pH, P is released due to the dissolution of Fe oxides/oxyhydroxides, as supported by scanning electron microscopy (SEM)/energy dispersive spectrometry (EDS). At high pH, P is desorbed from negatively charged Fe oxide/oxyhydroxide surfaces. The results of this investigation are pertinent to the design and operation of melter slag filters that treat all forms of P-rich waters, such as wastewater, stormwater, and farm runoff. The study demonstrated that P retention by melter slag filters is optimal in water bodies characterized by near-neutral pH and oxidizing Eh because these conditions favor P adsorption onto Fe oxides/oxyhydroxides.
Q-Index Code C1
Additional Notes Variant title: ES & T

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
Advanced Water Management Centre Publications
 
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