Evaluation of EOC removal processes during artificial recharge through a reactive barrier

Area of Science:

• Environmental Engineering
• Water Resource Management
• Geochemistry

Background:

• Emerging organic compounds (EOCs) pose risks to water resources.
• Infiltration basins are crucial for groundwater recharge but require contaminant removal.
• Engineered reactive barriers offer a potential solution for EOC remediation.

Purpose of the Study:

• To assess the efficacy of a reactive barrier in removing EOCs from recharge water.
• To quantify degradation rates and retardation factors of EOCs within the barrier.
• To evaluate the barrier's performance compared to natural aquifer conditions and previous studies.

Main Methods:

• Installation of a reactive barrier (vegetable compost, iron oxide, clay) in an infiltration basin.
• Utilizing a multilayer reactive transport model calibrated with hydraulic head and tracer tests.
• Estimating first-order degradation rates and retardation factors for 10 EOCs across different redox and organic matter zones.
• Automated calibration against measured EOC concentrations at nine monitoring points.

Main Results:

• The reactive barrier exhibited the fastest degradation rates for most EOCs (8/10 compounds).
• Estimated degradation rates were comparable to or exceeded those from prior column and field experiments.
• Retardation coefficients in the barrier were higher than in the surrounding aquifer for most compounds (8/10).
• The barrier demonstrated significantly higher EOC retention compared to previous studies.

Conclusions:

• The engineered reactive barrier effectively enhances the removal of emerging organic compounds.
• The barrier's design promotes faster degradation and greater retention of EOCs in recharge water.
• This approach shows significant promise for improving the quality of infiltrated water resources.