Zero-Valent Iron Permeable Reactive Barrier for In-Situ Remediation of Nitrate-Contaminated Aquifers

Abstract

Nitrate contamination in groundwater aquifers has become a critical environmental issue due to intensive agricultural practices, industrial discharge, and improper waste management, posing significant risks to drinking water quality and human health. The present study investigates the application of a zero-valent iron permeable reactive barrier for the in-situ remediation of nitrate-contaminated aquifers under varying hydrogeological conditions. The research focuses on evaluating nitrate removal efficiency, reaction mechanisms, hydraulic performance, and long-term operational stability of the reactive barrier system. Experimental analysis was conducted to examine the influence of groundwater flow rate, initial nitrate concentration, pH, reactive media composition, and residence time on nitrate reduction and contaminant transformation behavior. Results demonstrate that zero-valent iron effectively promotes nitrate reduction through abiotic redox reactions, converting nitrate into less harmful nitrogen species while simultaneously reducing contaminant mobility within the aquifer system. The study further reveals that optimized reactive barrier design and groundwater contact conditions significantly enhance treatment performance and improve remediation efficiency. Corrosion products generated during iron oxidation were found to contribute to additional adsorption and co-precipitation mechanisms that support nitrate removal. Comparative assessment with conventional ex-situ groundwater treatment technologies confirms that permeable reactive barriers provide advantages including lower operational costs, minimal energy requirements, and continuous passive remediation capability. In addition, the in-situ treatment approach minimizes disturbance to aquifer systems and supports long-term groundwater restoration.