Triangular shaped container to simulate radial flow fields
Figure 1. Triangular shaped container to simulate radial flow fields
I have written my PhD thesis on the work I have been performing at the Research Facility for Subsurface Remediation, VEGAS, which is a department of the Institute for Modelling Hydraulic and Environmental Systems at the University of Stuttgart
I had my exam on July 19, 2012, a link to an online version of my dissertation will follow.

In my research I worked with nano sized zero valent iron (nZVI) colloids. These colloids are capable of dechlorinating chlorinated hydrocarbons (e.g. PCE).
The research focussed on the feasibility of applying these colloids for in-situ remediation. My main focus was on the behavior of nZVI colloids during the injection into a porous medium.

My Ph.D. reviewing committee consisted of the following three professors:
Rainer Helmig, Ruud Schotting, Rajandrea Sethi

Transport of Nano Sized Zero Valent Iron Colloids during Injection into the Subsurface

My dissertation can be downloaded from OPUS

Structure of the Dissertation

To obtain a better description and understanding of the transport behavior of nZVI in porous media the research started at the fundamental of colloid filtration and worked this out through 1-D and 2-D experiments and numerical simulations to recommendations for the field, covering a wide range of scales. For this need, it was found that no non-destructive and direct measuring technique was available and thus had to be developed to describe and understand the transport behavior (Figure 2).

Overview of the dissertation
Figure 2. Overview of the structure of the dissertation

The work distinguishes four main chapters beside the introduction (Chapter 1).
Chapter 2 presents the developed quantitative non-destructive measuring and detection techniques based on the ferro magnetic property of nZVI to measure the nZVI concentration in the porous medium at the column, container and field scale. A chemical (destructive) analysis method was furthermore developed to provide a chemical verification method of the non-destructive measurements as well as to characterize nZVI suspensions.
Chapter 3 provides a description of colloid transport and constitutive relationships derived from the colloid filtration theory, column experiments and numerical simulations of the column experiments.
Chapter 4 focuses on the transport in a radial flow field. A large scale container experiment (Figure 1) is presented. The results of this experiment were used to verify a quick screening column experiment and a numerical predictive model.
Chapter 5 shows how the experiments and the numerical simulations provide a method to test the injection feasibility and can be used to design a field application. Recommendations and the preferred approach for the design are presented.
At the end of the work the answers on the research questions are summarized in the conclusion and an outlook provides further research topics that could be performed.

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