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Retention of Metals in Sewage Sludge I: Constituent Heavy Metals
Author(s) -
Lagerwerff J. V.,
Biersdorf G. T.,
Brower D. L.
Publication year - 1976
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/jeq1976.00472425000500010003x
Subject(s) - chemistry , leachate , leaching (pedology) , sewage sludge , environmental chemistry , aqueous solution , metal , fractionation , heavy metals , nuclear chemistry , sewage , soil water , chromatography , environmental engineering , geology , organic chemistry , soil science , engineering
Sewage sludge from Baltimore, Md. was compared to that of Washington, D.C. in terms of the tendency to release heavy metals under a variety of circumstances. Total and 1.0 N HCl‐extractable concentrations of Cd, Cu, Pb, and Zn were determined by atomic absorption spectrophotometry. Fractionation of the metals by leaching columned samples of Baltimore sludge, with either a CaCl 2 solution or H 2 O over extended periods of time, showed Cd and especially Zn were more leachable than Cu and Pb. Except for Pb, leachability of the metals was much lower in the sludge from Washington, D.C. than in the Baltimore sludge. Regarding the sign of charge of Cu species as a function of the progression of leaching of Baltimore sludge, anionic and, especially, amphoteric species increased, as cationic ones decreased. When aqueous sludge leachates were stored for 13 months at 5C, amphoteric Cu strongly increased, while all other Cu species decreased. In contrast, nearly all Zn species in the stored leachates were cationic. When sludge samples were subjected to simulated weathering by stirring with either H 2 O 2 in a number of concentrations, or H 2 O, followed by steambath drying, the extractability of heavy metals with H 2 O and 0.01 N HCl increased. Extractability of Cu increased more than that of Cd or Zn, suggesting that the stability of the amphoteric Cu species depended strongly on acidity. Because of the H 2 O 2 treatments, the cation exchange capacity of the sludges diminished by 15 to 25% depending on their origin, although no C was lost. Compared with Washington, D.C. sewage sludge, Baltimore sludge had a greater heavy metal contaminating potential for soil amended with it.