Solid phosphorus phase in aluminum- and iron-treated biosolids.
J Environ Qual
; 36(2): 549-56, 2007.
Article
em En
| MEDLINE
| ID: mdl-17332259
ABSTRACT
Stabilization of phosphorus (P) in sewage sludge (biosolids) to reduce water-soluble P concentrations is essential for minimizing P loss from amended soils and maximizing the capacity of the soil to safely serve as an outlet for this waste material. The chemical form at which P is retained in biosolids stabilized by Al(2)(SO(4))(3) x 18H(2)O (alum) or FeSO(4) x 7H(2)O (FeSul) was investigated by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray elemental spectrometry (EDXS) and by X-ray diffraction (XRD). Both treatments resulted in the formation of a Ca-P phase, probably brushite. Phosphorus was further retained in the alum-treated biosolids by precipitation of an Al-P phase with an Al/P molar ratio of about 11, while in the FeSul-treated biosolids, P was retained by both precipitation with Fe/P molar ratios of 11 or 1.51, and by adsorption onto newly formed Fe hydroxides exhibiting an Fe/P molar ratio of up to 111. All of these mechanisms efficiently reduced P solubility and are crucial in biosolids environmentally safe agronomic beneficial use for this waste product; however, each P phase formed may react differently in the amended soil, depending on soil properties. Thus, the proper P stabilization method would depend on the target soil.
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MEDLINE
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Idioma:
En
Ano de publicação:
2007
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Article