Kinetics of di-(2-ethylhexyl)phthalate mineralization in sludge-amended soil
- Aalborg Univ. (Denmark). Environmental Engineering Lab.
Sewage sludge is frequently used as a soil fertilizer although it may contain elevated concentrations of priority pollutants including di-(2-ethylhexyl)phthalate (DEHP). In the present study, the kinetics of microbial [[sup 14]C]DEHP mineralization was studied in laboratory microcosms with sewage sludge and agricultural soil. A biphasic model with two independent kinetic expressions was used to fit the mineralization data. The initial mineralization activity was described well by first-order kinetics, whereas mineralization in long-term incubations was described better by fractional power kinetics. The mineralization activity was much lower in the late phase presumably due to a decline in the bioavailability of DEHP caused by diffusion-limited desorption. The initial DEHP mineralization rate in sludge-amended soil varied between 3.7 and 20.3 ng of DEHP (g dw)[sup [minus]1]d[sup [minus]1] depending on incubation conditions. Aerobic DEHP mineralization was 4--5 times faster than anaerobic mineralization, DEHP mineralization in sludge-amended soil was much more temperature sensitive than was DEHP mineralization in soil without sludge. Indigenous microorganisms in the sewage sludge appeared to dominate DEHP degradation in sludge-amended soil. It was estimated that > 41% of the DEHP in sludge-amended soil will have escaped mineralization after 1 year. In the absence of oxygen, > 68% of the DEHP will not be mineralized within 1 year. Collectively, the data suggest that a significant fraction of the DEHP in sludge-amended soils may escape mineralization under in situ conditions.
- OSTI ID:
- 6377730
- Journal Information:
- Environmental Science and Technology, Journal Name: Environmental Science and Technology Vol. 33:15; ISSN ESTHAG; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
BIOLOGICAL AVAILABILITY
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
CARBOXYLIC ACID SALTS
CHEMISTRY
GROUND DISPOSAL
MANAGEMENT
MATERIALS
MATHEMATICAL MODELS
MICROCOSMS
MINERALIZATION
PHTHALATES
SEWAGE
SEWAGE SLUDGE
SLUDGES
SOIL CHEMISTRY
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES