Injections and transfer

EKOGRID™ technology can be used in conjunction with other remediation methods when treating contaminated soils and groundwater. The most frequently used combinations to date include coupling EKOGRID with pump & treat systems and with other additive based enhanced bioremediation solutions.

In standard remediation (induced electrolysis) mode, EKOGRID™ pulses are equally timed in both directions between the electrode rows. In addition to inducing electrolysis the low voltage current makes the charged contents of the pore water move back and forward resulting in the electrokinetic mixing effects at the soil particle level but no bulk movement in the direction of any electrode.

In transfer mode the EKOGRID™ control unit generates longer pulse in one direction than in the other direction. The uneven pulse pattern results in the movement of soil cations, other soluble elements and water through the soil and groundwater in a direction determined by the transfer pulse.

The transfer mode set up can be used in a wide variety of setups.  It is typically used in conjunction with the standard EKOGRID (even pulse) set up on remediation projects. The control unit will be switched to transfer mode when nutrient additives are applied in order to spread the nutrients through the soil. Soil nutrient content is often the limiting factor with enhanced bioremediation. The control unit will then be switched back to an even pulse pattern to continue the electrokinetic enhance bioremediation processes.

The transfer mode can also be used purely to increase the effectiveness of other remediation approaches:

• Pump and Treat: Cathodes are installed in the pumping wells and anodes to areas where the contaminants are located. The transfer pulse is set to enhance movement towards the cathodes. Flow of water is enhanced significantly and the gradient towards the well is increased.
• Distributing additives: When adding remediation additives, whether they be nutrients, enzymes, surfactants or other chemicals, getting the additives to distribute through the area of contaminated land can be challenging. The utilization of the EKOGRID system in transfer mode can vastly speed up the spread of additives. Additives can be applied by a drip-line type of irrigation system between the electrode rows or perforated tubular electrodes can be used and the additives injected into the soil directly at the electrodes.

The diagram below illustrates the operation of a transfer pulse with the longer pulse set from blue electrodes to red electrodes, thus creating a push of water and additives towards the red electrodes.