Phosphorus Speciation in Drinking Water Treatment Residuals (WTRs) and Biosolids-Amended Soils Using XANES Spectroscopy

Abstract

X-ray absorption near-edge structure (XANES) spectroscopy (a non-destructive chemical-speciation technique) is a useful technique available for determining the speciation of P in various environmental samplesTwo incubation studies were conducted to assess the P species formed in an originally neutral and alkaline soil in response to high biosolids and/or WTRs applications using P K-edge X-ray absorption near edge structure (XANES) spectroscopy. The results indicated that combination of P standards yielding the best linear combination fits for biosolids were phytic acid (26.03%) and Cu₃(PO₄)₂ (73.09%) and a little of P-sorbed to Al hydroxide (0.89%). However, The combination of P standards yielding the best linear combination fits for WTRs were P-sorbed to Fe hydroxide (64.19%), phytic acid (30.72%) and P-sorbed to Al hydroxide (5.07%). The P speciation in 10 g kg^-1-treated clay soils were phytic acid (19.08%), Mn₃ (PO₄)₂ (0.79%), Phytic acid(K,Mg salt)(11.22%), Cu₃(PO₄)₂ (7.26%), and hydroxyapatite (57.98%). Addition of WTRs modified the P speciation in biosolids-amended soils, and the changes varied depending on biosolids and WTRs application rates. The P speciation in soils depends on the soil type and application rates of biosolids and WTRs.

Keywords: Biosolids, P, XANES, WTRs, Soils