Horizontal Electrode Arrays for In-Situ Soil Remediation
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Solution Overview
Problem
Conventional in-situ soil remediation methods, such as soil vapor extraction, are ineffective in less permeable soils, limiting the treatment area and efficiency, and previous electric soil heating systems have not shown consistent results in contaminant mobilization.
Innovation Solution
The method involves placing horizontally oriented electrodes with electrically conductive particulate matter in bore holes to create an electric field, inducing contaminant mobilization through electromigration, and optionally using heating to increase contaminant volatility for enhanced removal via vapor extraction or flushing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If soil vapor extraction is used to treat contaminated subsurface soil, then contaminants can be removed from the soil, but the method is ineffective in less permeable soils, limiting the treatment area and efficiency
Solution Approach 1:
The patent applies electrical parameters (voltage, current, electric field strength) to change the physical state and mobility of contaminants in the soil. By controlling the electrical field parameters, the system can effectively treat contaminants in less permeable soils where traditional vapor extraction fails, thus changing the operational parameters to adapt to different soil permeability conditions
Solution Approach 2:
The patent replaces the mechanical vacuum-based vapor extraction system with an electrical field-based remediation system. Instead of relying on mechanical suction through permeable pathways, the system uses electrical forces (electromigration, electroosmosis, electrophoresis) to mobilize and transport contaminants, making it effective in soils with low permeability where mechanical methods fail
2Area of stationary object
If pneumatic fracturing or heat treating methods are used to increase soil permeability, then the effective range of soil vapor extraction can be increased, but the process becomes more complex and resource intensive
Solution Approach 1:
The electrical field system performs multiple functions simultaneously: it mobilizes contaminants through electromigration, transports them via electroosmosis, and can heat the soil to enhance contaminant volatility. This multi-functionality eliminates the need for separate permeability enhancement treatments like pneumatic fracturing or heat treating, reducing overall system complexity while expanding treatment area
Solution Approach 2:
The patent combines contaminant mobilization, transport, and soil heating functions into a single electrical field-based system. By merging these functions that were previously achieved through separate complex processes (pneumatic fracturing, heat treating), the system achieves broader treatment area coverage with reduced operational complexity
3Temperature
If electric soil heating systems are used to mobilize contaminants, then contaminant volatility can be increased, but previous attempts have not shown consistent or promising results
Solution Approach 1:
The system uses a composite approach combining electrical heating with electrically conductive particulate materials (such as carbon or graphite) mixed with the soil. This composite structure ensures uniform heat distribution and consistent electrical field application, leading to reliable and consistent contaminant mobilization and soil heating results that previous single-method systems failed to achieve
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach extends the treatment area and enhances contaminant removal efficiency in less permeable soils by creating a uniform electrical field and concentrating contaminants around electrodes, allowing for fewer bore holes and more effective contaminant extraction.
Implementation Method 1
passing an electric current between the first electrode and second electrode through the soil between the first electrode and second electrode, using the first electrode and second electrode, the first electrode having opposite charge from the second electrode, to induce mobilization of contaminants in the soil between the first electrode and second electrode towards at least one of: the first electrode and second electrode
Implementation Method 2
heat treating methods to decrease the viscosity and increase the volatility of fluids in the soil
Data Source
AI summary
A method for in-situ soil remediation is provided. Electrodes are placed below the ground surface extending horizontally. The electrodes are positioned such that a first electrode is positioned above a second electrode and the electrodes surround a region of soil containing contaminants. A plurality of electrodes can be placed in an upper plane corresponding with a plurality of electrodes placed in a lower plane. By passing a current between the electrodes contaminants are mobilized towards the electrodes where the contaminants can be extracted. The electrodes are constructed by boring substantially horizontal bore holes, inserting a well screen in the bore hole and packing an annulus formed between the well screen and the bore hole with electrically conductive particulate matter.