Chemical fractionation of phosphorus in stabilized biosolids.
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.
Huang
Xiao-Lan
XL
Dep. of Soil and Water Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew Univ. of Jerusalem, Rehovot 76-100, Israel.
Chen
Yona
Y
Shenker
Moshe
M
D000534:Alum Compounds / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry*; D012987:Soil
D000534:Alum Compounds; D017610:Calcium Compounds; D005296:Ferrous Compounds; D010087:Oxides; D012722:Sewage; D012987:Soil; D010758:Phosphorus; C041524:aluminum sulfate; C020748:ferrous sulfate; D002244:Carbon; C016538:lime