Extractability of heavy metals in wastewater solids undergoing anaerobic digestion
The extractability of heavy metals in wastewater sludge undergoing anaerobic digestion was investigated. Using batch laboratory digesters, raw wastewater sludge was anaerobically digested at different raw sludge solids loadings and two temperatures. From each of the laboratory digesters, wastewater sludge was sampled at three day intervals and sequentially separated into seven extraction fractions and analyzed for the metals Cu, Cr, Cd, Fe, Ni, and Pb. The seven step sequential extraction was for metal species: (a) soluble, (b) displaced-exchangeable, (c) adsorbed, (d) organic, (e) carbonate, (f) sulfide-acid soluble, and (g) residual. At the 35/sup 0/C digestion temperature the distribution of metals in the extractant fractions between the raw and anaerobically digested sludges were significantly different. For the 45/sup 0/C digestion temperature the distribution of metals in the raw and digested sludge extractant fractions were different and different compared to the 35/sup 0/C system. The 45/sup 0/C raw sludge showed greater percent metal in the organic and sulfide-acid soluble fraction than the digested sludge. At the 45/sup 0/C anaerobic digestion temperature the percent of raw sludge solids loading in the digester had a greater effect on changes in metal extractability and proposed metal species than the 35/sup 0/C.
- Research Organization:
- Rutgers--the State Univ., New Brunswick, NJ (USA)
- OSTI ID:
- 5244398
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ANAEROBIC DIGESTION
BIOCONVERSION
CADMIUM
CHROMIUM
COPPER
DIGESTION
ELEMENTS
EXTRACTION
HYDROGEN COMPOUNDS
IRON
LEAD
LIQUID WASTES
MANAGEMENT
METALS
NICKEL
OXYGEN COMPOUNDS
PROCESSING
SEPARATION PROCESSES
SLUDGES
TRANSITION ELEMENTS
WASTE MANAGEMENT
WASTE PROCESSING
WASTE WATER
WASTES
WATER