Date of Award

Spring 1999

Document Type

Thesis

Degree Name

Master of Science in Environmental Engineering - (M.S.)

Department

Civil and Environmental Engineering

First Advisor

Jay N. Meegoda

Second Advisor

John R. Schuring

Third Advisor

Robert Dresnack

Abstract

In this research, it was attempted to decontaminate and separate dredged sediments contaminated with organic compounds by the application of ultrasound energy coupled with sub-atmospheric pressures. The decontamination and separation of contaminated sediments was achieved by integrated two processes. For Process 1, ultrasound energy was used to decontaminate the sandy fraction in dredged sediments, and sub-atmospheric pressure was used to separate and remove fines. For Process 2, ultrasound was again used to decontaminate fines with bulk fluid, and sub-atmospheric pressure was used to remove the contaminants with water. Process 1 was evaluated and found to have four variables contributing to its performance: power, solvent to sediment ratio, pressure, and sonication time. Process 2 was evaluated with and without surfactants. Process 2 without surfactant had three variables: power, solvent to sediment ratio, and sonication time, while Process 2 with surfactant had four variable contributing to its performance: power, solvent to sediment ratio, surfactant concentration, and sonication time. Both processes were optimized by analyzing experimental data using SAS statistical software. The percentage of removal efficiency was considered as the dependent variable. Statistical models were developed based on the experimental results to optimize the process conditions. Statistical analysis showed that Process 1 had 98% contaminant removal efficiency at 58% power, 14:1 solvent to sediment ratio, 16-psi vacuum pressure, and 8 minutes of sonication time. Similarly, Process 2 without the surfactant had 99% contaminant removal efficiency at 75% power, 41:1 solvent to sediment ratio, and 95 minutes of sonication time. Process 2 with the surfactant had 99% contaminant removal efficiency at 57% power, 32:1 solvent to sediment ratio, 0.08% surfactant concentration, and 74 minutes of sonication time.

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