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Chemical Fractionation of Phosphorus in Stabilized Biosolids
Author(s) -
Huang XiaoLan,
Chen Yona,
Shenker Moshe
Publication year - 2008
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2007.0220
Subject(s) - biosolids , fractionation , chemistry , alum , extraction (chemistry) , compost , sewage sludge , ferrous , sulfate , environmental chemistry , phosphorus , calcium oxide , nuclear chemistry , sewage treatment , environmental engineering , chromatography , waste management , organic chemistry , engineering
Three chemicals—ferrous sulfate (FeSul), calcium oxide (CaO), and aluminum sulfate (alum)—were applied at different rates to stabilize P in fresh, anaerobically digested biosolids (FBS) obtained from an activated sewage treatment plant. A modified Hedley fractionation procedure was used to assess P forms in these sludge‐borne materials and in a biosolids compost (BSC) prepared from the same FBS. Each biosolids material exhibited a unique pattern of P distribution among fractions. The most available P forms, namely: (i) water‐soluble P (WSP); (ii) membrane‐P; and (iii) NaHCO 3 –P, were stabilized by small rates of each of the chemicals; but the P transformation into more stable forms depended on the type of chemical added. The stabilized P forms were enhanced by high rates of CaO and FeSul, but were reduced by high rates of alum. The organic P (P o ) in the first three fractions of the FeSul‐ and alum‐stabilized biosolids was enhanced by the chemical addition, and P o transformation from NaOH‐P o into NaHCO 3 –P o was found in calcium‐stabilized biosolids. A positive relationship was found between NaHCO 3 –P o and the NaHCO 3 –extracted organic C in all chemically stabilized biosolids. One‐step extraction by NaHCO 3 or NaOH underestimated P extraction compared to the stepwise extraction. The reported results are consistent with solid‐state P speciation reported earlier and contribute important information for optimizing biosolids stabilization to reduce P loss after incorporation in soils and for maximizing soil capacity to safely store pre‐stabilized biosolids.