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Institute of Hydraulic Engineering

Research: VEGAS - Research Facility for Subsurface Remediation

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Alcohol Flushing: Parameter Estimation for a cost efficient in-situ remediation of an aquifer contaminated with DNAPL
Project manager:Jürgen Braun, Ph.D.
Deputy:Dr.-Ing. Hans-Peter Koschitzky, AD
Research assistants:Dr.-Ing. Philipp Greiner
Dipl.-Ing.(FH) Johannes Schnieders
Dipl.-Ing.(FH) Oliver Trötschler
Dr. rer.nat. Karolin Weber, M.Sc.
Duration:1.1.2001 - 31.12.2004
Funding:Bundesministerium für Bildung und Forschung (BMBF)
Project Partners:Institut für Hydromechanik der Universität Karlsruhe (IfH)
Comments:

This project is part of the research area:
In-Situ Remediation Technologies

Publications: Link

Abstract:

The intention of this project is to develop an efficient in-situ-technology to remove chlorinated hydrocharbons from the saturated zone. Using a groundwater circulation well (GCW) the alcohol cocktail is injected into the aquifer and flushed through the contaminated zone. The solubilised and controlled mobilised contaminant is subsequently extracted by a GCW from the aquifer.

The Institute for Hydromechanics (Universität Karlsruhe) is working on the hydraulically controlled alcohol injection using a GCW. The solubilisation and controlled mobilisation of chlorinated hydrocharbons is investigated at the Institute of Hydraulic Engineering (University of Stuttgart).

Based on different scale experiments and numerical modelling, an effective in-situ-remediation technology is being developed.

In batch- and column experiments, a suitable alcohol cocktail was selected and its behaviour in the porous media and with the contaminant was investigated. 2D-box and large tank experiments were used to investigate the hydraulic system and to estimate the remediation time. Also, experiments on different scales were conducted to investigate the use of partitioning tracer tests (PTT) to detect DNAPL source zones.

The experimental results were used to develop a new mode for the numerical model STOMP. The equations for the relevant parameters (density-, viscosity changes, phase behaviour and change of the interfacial tension) were implemented in the numerical model.

A large tank experiment was conducted in the VEGAS block model (length: 9 m, width: 6 m, height: 4,5 m). By injecting 15,36 kg
(= 9,5 l) of PCE a contaminated zone with the extention of approx. 1,5 m * 0,7 m* 0,9 m (l*w*h) was created. A GCW was drilled through the contaminated zone. Using the GCW an alcohol cocktail consisting of 54% 2-propanol, 23% water and 23% 1-hexanol was injected into the aquifer with a pumping rate of 540 l/h for 8 h. Afterwards, a mixture consiting of water and 2-propanol was injected for 6 h with a pumping rate of 330 l/h followed by the injection of pure water for 12 h with the same pumping rate. After a test duration of 26 h the contamination was safely and efficiently removed from the artificial aquifer.

In a next step the efficiency of this technique will be demonstrated in a field pilot test.

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