Reactive media in permeable reactive barriers for selenium removal

Overview

The proposed solution involves a passive permeable reactive barrier (PRB) design that employs a combination of sulfidized zero-valent iron (S-ZVI), granulated drinking water treatment residuals (WTRs), and Filtrasorb-400 (F-400) to effectively remove selenium from groundwater. This innovative approach capitalizes on the natural groundwater flow, eliminating the need for active pumping or chemical feeds. The S-ZVI component is engineered with a controlled sulfur-to-iron ratio, creating an FeS-rich surface that enhances electron transfer and accelerates the reduction of selenium compounds to less mobile forms. The WTRs provide additional adsorption sites for selenium and arsenic, while F-400 adds structural stability and supplemental adsorption capacity.

Technical specifications

• S-ZVI preparation: Controlled S/Fe molar ratio for optimal FeS surface formation.
• WTRs: Fe/Al-oxides/hydroxides-rich material for oxyanion adsorption.
• F-400: High-surface-area carbon support for enhanced hydraulic stability.
• Layered PRB structure: Incorporates S-ZVI/WTR/F-400 core with WTR conditioning and polishing layers.
• Functionality: Passive operation under natural gradients, no external power or chemical input required.

Technology readiness level

Currently, the technology is at a TRL 2 stage, involving lab-scale validation and development of an optimized media recipe and PRB design for scale-up. Initial tests focus on media characterization, batch testing, and lab-scale column trials to refine media combinations and configurations for effective selenium and arsenic management.