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Induced Polarisation (IP) Laboratory Measurements on Escherichia Coli (E. Coli)-Sand Mixtures
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 25th European Meeting of Environmental and Engineering Geophysics, Sep 2019, Volume 2019, p.1 - 5
Abstract
Summary
For the characterization and monitoring of in-situ remediation of chlorinated hydrocarbon contamination, interdisciplinary approaches and geophysical methods are needed to secure water supply of sufficient quality and quantity. Geophysical methods, such as IP (induced polarisation) could be used to investigate bioremediation processes. However, to interpret geophysical field IP data, lab investigations with different kinds of bacteria are necessary to assess the sensitivity of the methods for these specific applications. Therefore, a first experiment was conducted with E. coli bacteria in sterilised Ottawa sand environment. These bacteria-sand-mixtures were harvested at different days and measured with e.g., SIP (spectral IP) under laboratory conditions. A slight increase in phase and a decrease in resistivity were observed after several days of bacterial growth with sand, with a later decrease in phase appearing to coincide with die-off of the bacteria. Scanning electron microscope (SEM) images showed bacteria attached to the sand grains which could modify the grain surface (e.g. increasing the grain surface area and/or form a biofilm) and thus impact IP measurements. In future, the number of bacteria present in the sand will be determined using quantitative polymerase chain reaction (qPCR) to detect bacterial DNA (deoxyribonucleic acid).
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