X‐Ray Spectroscopic Quantification of Struvite and Dittmarite Recovered from Wastewater
- Dep. of Earth and Environmental Sciences California State Univ. East Bay 25800 Carlos Bee Blvd., North Science Building, Room N329 Hayward CA 94542
Phosphorus recovery from wastewater as struvite (MgNH 4 PO 4 ⋅6H 2 O) or dittmarite (MgNH 4 PO 4 ⋅H 2 O) can decrease water pollution risk, as well as produce a P‐rich material suitable as fertilizer. However, most studies to date have focused on the removal of P from wastewater, rather than on characterization of the recovered P materials. The objective of this work was to apply microfocused X‐ray fluorescence (XRF) spectroscopy, and both bulk and microfused X‐ray absorption near edge structure (XANES) spectroscopy, to provide insight into the speciation of recovered P in various struvite‐containing and struvite‐like materials. Three materials were investigated: homogeneous crystalline struvite on apatite seed, homogeneous dittmarite, and heterogeneous struvite with sand contamination (referred to as the “sandy” material). The struvite materials were recovered from dairy wastewater, whereas the dittmarite was from a cheese processing plant. Phosphorus speciation in the crystalline struvite on apatite seed material was ∼17% apatite and 83% struvite; in the “sandy” material, P was ∼24% apatite and ∼76% struvite, with an uncertainty of approximately ±15%. The P K ‐edge XANES spectra of recovered dittmarite appeared pure. These findings highlight the heterogeneity of recovered P materials and underscore the importance of P speciation to understand P release behavior and bioavailability from recovered phosphates.
Core Ideas
Multiple methods should be used to corroborate spectroscopic estimates of P speciation.
Dittmarite P K ‐edge XANES spectra are distinct from spectra of chemically similar struvite.
Phosphorus K ‐edge XANES spectroscopy can quantify Mg‐associated P >15 atom% P.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1582083
- Journal Information:
- Journal of Environmental Quality, Journal Name: Journal of Environmental Quality Journal Issue: 1 Vol. 48; ISSN 0047-2425
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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