Abstract:
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Water used in Managed Aquifer Recharge (MAR) systems can contain organic
micropollutants, which can contaminate the aquifer. The degradation rates of many of
these compounds can be enhanced by cometabolism linked to redox processes. Previous
studies have shown that the addition of Dissolved Organic Carbon (DOC) into the
recharge flow enhances micropollutant degradation rates by promoting redox reactions.
With the aim of improving the reactivity of the system by enhancing mixing between the
recharge solution and groundwater, an Engineered Injection and Extraction protocol has
been proposed and numerically optimized to generate chaotic advection around the
recharge area. As a second goal of the project, a laboratory experiment to test a reducedscale
version of the system has been designed. The results show that the optimal stirring
protocol depends on the hydraulics and chemistry of the aquifer and the MAR system.
For the specific configuration of the laboratory experiment, several stirring protocols
displayed close to optimal performance according to the optimization results. Four of
them were tested in a conservative transport numerical model. For all of them, results
show a dramatic increase in mixing. This suggests that this kind of EIE systems have a
potential to enhance micropollutant degradation in MAR systems when combined with
DOC addition to the recharge solution. |