Content and fractionation of heavy metals in water treatment sludges

Journal Article · · Journal of Environmental Quality; (USA)

DOI:https://doi.org/10.2134/jeq1990.00472425001900020021x· OSTI ID:6174504

Elliott, H A; Dempsey, B A; Maille, P J ^[1]

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1. Pennsylvania State Univ., University Park (USA)

The composition and distribution of Cd, Cu, Cr, Ni, Pb, and Zn in eight alum and FeCl{sub 3} coagulation sludges were investigated using a five-step chemical fractionation procedure to assess potential impacts following soil incorporation. The mean total metal levels (mg kg{sup {minus}1} dry wt.) for these sludges were Cd (<2), Cu (234), Cr (187), Ni (102), Pb (230), and Zn (557), which are well below maximum allowable levels for land-applied wastes. Two individual FeCl{sub 3} sludges had Ni levels slightly above maximum allowable concentrations. Mean total Cr and Ni concentrations in the FeCl{sub 3} sludges were, respectively, 5.4 and 3.1 times the corresponding alum sludge levels, reflecting elevated concentrations in the FeCl{sub 3} coagulant. The Cu, Cr, Ni, Pb, and Zn in sludges were predominantly bound within the oxide or silicate components. A small portion of the sludge Cd was in a readily exchangeable form, whereas the dilute acid extractable and organically bound fractions contained the majority of nonresidual Cd. Fractionation results suggest sludge Cd would potentially be mobile under acidic soil conditions, but the total Cd levels were very low (1-2 mg kg{sup {minus}1} compared with an allowable maximum of 25 mg kg{sup {minus}1}). Although fractionation data must be interpreted cautiously, the results suggest most metals in water treatment sludges occur predominantly in weakly mobile, nonbioavailable forms.

• OSTI ID: 6174504
• Journal Information: Journal of Environmental Quality; (USA), Journal Name: Journal of Environmental Quality; (USA) Vol. 19:2; ISSN JEVQA; ISSN 0047-2425
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540210* -- Environment
Terrestrial-- Basic Studies-- (1990-)
BIOLOGICAL AVAILABILITY
CADMIUM
CHEMICAL COMPOSITION
CHROMIUM
COPPER
ELEMENTS
FRACTIONATION
GROUND DISPOSAL
LEAD
MANAGEMENT
METALS
NICKEL
SEPARATION PROCESSES
SEWAGE
SEWAGE SLUDGE
SLUDGES
SOILS
TRANSITION ELEMENTS
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER TREATMENT
ZINC