Superfund Research Program
Green Remediation by Solar Energy Conversion into Electrolysis in Groundwater
Project Leader: Akram N. Alshawabkeh
Grant Number: P42ES017198
Funding Period: 2010-2024
Project Summary (2010-2014)
The US EPA supports the adoption of green remediation, which considers all environmental effects and incorporates strategies to maximize the net environmental benefit. Dr. Akram Alshawabkeh’s long-term goal is to develop a green remediation process based on conversion of solar energy into iron electrolysis in groundwater. Electrolysis of sacrificial iron anodes will cause chemical reduction of contaminants, including chlorinated solvents in groundwater. The kinetics of iron redox in a two-electrode electrolysis system and release of ferrous ions and hydrogen gas can be optimized by controlling the electric current density and polarity for effective transformation of contaminants. The process is suited for karstic groundwater aquifers because the dynamic flow conditions in channels and fractures require controlled rates of iron reactivity. The process uses solar energy and will not produce adverse effects on groundwater environment. Dr. Alshawabkeh is:
- evaluating the effect of iron electrolysis on groundwater geochemistry,
- demonstrating the transformation of trichloroethylene (TCE) as a model nonpolar organic contaminant in groundwater by iron electrolysis under batch and flow conditions,
- evaluating the effects of polarity reversal and voltage/current intensity,
- developing a predictive tool "model" for transformation,
- evaluating the effects on the physical properties of the aquifer, assess the cytotoxicity of treated water, and
- evaluating any adverse effects on the fate of other contaminants (e.g., semipolar organics such as phthalates).
The researchers are conducting experiments in cells using karst aquifer characteristics, including experimental setups that are constructed of limestone blocks. The plan includes 2D lab pilot-scale testing using the GeoBed (developed by Dr. Ingrid Padilla) and a small-scale field test. The primary experimental variables being controlled are the water flow rate, electric current/voltage and electrolyte type. The primary dependent variables that are being monitored are pH, ORP, Dissolved Oxygen, alkalinity, cation and anion concentrations, contaminant concentration, ferrous and ferric ion concentrations, precipitates, electrical conductivity, and voltage/current. A model that couples Faraday's law for iron electrolysis and reactive flow are being developed and verified. The researchers are assessing power requirements and engineering a strategy that utilizes solar panels for field implementation.