Date of Award

1997

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

First Advisor

Roger K. Seals

Second Advisor

John H. Pardue

Abstract

Electrokinetics is one of the most viable alternatives for injecting/extracting water, organic and ionic species in low permeability soils as well as heterogeneous media because the transport processes are independent of the pore sizes. A better understanding of the principles offers the opportunity to employ multi-component species transport under electrical fields to inject electron acceptors, nutrients and other process additives for enhancement of in-situ bioremediation in low permeability and heterogeneous media. This study assesses the potential to employ and exploit the principles of multi-component species transport under electrical fields as mean to supplement, enhance and engineer in-situ bioremediation. It was determined that ammonium, sulfate, nitrate and phosphate ions can be injected in different types of soils and in a layered deposit with significantly different hydraulic and electrical conductivities. Ions transport rates of 8 to 20 cm/day occurred under current densities of 15 to 150 mA/cm$\sp2$ and voltage gradients less than 1 V/cm. A uniform distribution of the process additives could be achieved across the electrodes. These results are quite encouraging and demonstrate that the electrokinetics injection scheme has significant potential for in-situ bioremediation in low permeability soil as well as heterogeneous media. The transportability of the injected ions also depend on the charge concentration of the other competing ions on the pore fluid. The accumulation of these pore fluid ions in the system would decrease the transference number of the injected ions. The transportability of the injected ions could be increased by flushing intermittently or continuously the electrodes compartments to decrease the conductivity at the boundaries, which would increase the initial pore fluid ions to be flushed out from the system.

ISBN

9780591724141

Pages

221

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