Title page for ETD etd-04122005-200025
|Type of Document
||Fountain, Kenneth Alexander
|Author's Email Address
||Mathematical Models for Estimating Volatile Chemical Emissions from Dredging Operations
||Master of Science in Chemical Engineering (M.S.Ch.E.)
|Louis J. Thibodeaux
|Kalliat T. Valsaraj
|William M Moe
- chemical flux
|Date of Defense
Dredging operations have been a common remediation for contaminated sediment in an effort to reduce the harmful impact on the environment. The objective of this research was to create models used for estimating chemical release to air from remediating the Indiana Harbor and Canal (IHC) as three separate dredging operations; the Dredge Site, Exposed DM CDF, and Ponded CDF. The evaporative flux estimations are based on a two-resistance mass transport path inclusive of both the molecular diffusion in porous media and interfacial airside mass transport resistances. Several chemodynamic algorithms were used in calculating key transport parameters. Laboratory tests were performed to measure sediment-to-water partitioning and Henry's constant for IHC sediment.
A large portion of the research effort involved investigating by experiments and theoretical models dedicated to the chemical emissions from exposed dredge material. The study of the short term effects of exposure to these contaminants are very important because of the chemical flux quick release at the initial stages from filling and reworking of the dredged material (DM). Data is available for PAH/PCB volatilization from laboratory and pilot-scale flux chamber experiments using DM. However, larger scale or field sites data are required to further validate or test existing predictive mathematical models. A wind tunnel enclosure (16 ft length x 4 ft height x 3 ft width) fitted atop a lysimeter (1.5 ft depth) suited for simulating CDF conditions was used to measure chemical flux release from the DM. Most algorithms previously developed for estimating the chemical release from sediment are based on transport through natural surface soils, which are simpler than those for DM. The latter undergo dramatic physical changes as consequences of water consolidation and evaporation. The model flux estimates were generally lower than the measured ones. Apparently the copious quantities of water and its upward movement delivered fine particles containing enhanced chemical concentrations onto the surface layer and this higher than bulk concentration was driving the measured flux.
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