Testing the Suitability of Zerovalent Iron Materials for Reactive Walls

Chicgoua Noubactep,B J Merkel,Günther Meinrath,Martin Sauter,Peter Dietrich

doi:10.1071/en04014

Chicgoua Noubactep, B J Merkel + Show 3 more

Open Access

https://doi.org/10.1071/en04014

Copy DOI

Abstract

Environmental Context. Groundwater remediation is generally a costly, long-term process. In situ remediation using permeable reactive barriers, through which the groundwaters pass, is a potential solution. For redox-sensitive contaminants in groundwater, a metallic iron barrier (zerovalent iron, ZVI) can immobilize or degrade these dissolved pollutants. Scrap iron materials are a low-cost ZVI material but, because of the wide variation of scrap metal compositions, testing methods for characterizing the corrosion behaviour need to be developed. Abstract. Zerovalent iron (ZVI) has been proposed as reactive material in permeable in situ walls for contaminated groundwater. An economically feasible ZVI-based reactive wall requires cheap but efficient iron materials. From an uranium treatability study and results of iron dissolution in 0.002 M EDTA by five selected ZVI materials, it is shown that current research and field implementation is not based on a rational selection of application-specific iron metal sources. An experimental procedure is proposed which could enable a better material characterization. This procedure consists of mixing ZVI materials and reactive additives, including contaminant releasing materials (CRMs), in long-term batch experiments and characterizing the contaminant concentration over the time.

Highlights

Groundwater contamination is one of the most difficult and expensive environmental problems.[1, 2, 3] The most common technology used for remediating groundwater has been to pump the water and treat it at the surface.[4]
The aim of this paper is to propose an experimental method efficient at: (1) characterizing the reactivity of a Zerovalent iron (ZVI) for field application irrespective from the nature of the pollutant, and (2) investigating the long term reactivity of ZVI under specific conditions using reactive materials to create simulated conditions
Uranium removal: Table 3 compares the percent of irreversible U(VI) fixation (PU) by the five tested ZVI materials

Summary

Introduction

Groundwater contamination is one of the most difficult and expensive environmental problems.[1, 2, 3] The most common technology used for remediating groundwater has been to pump the water and treat it at the surface (pump-and-treat technology).[4]. Operating permeable reactive walls treat contamination as halogenated hydrocarbons, chromium, nitrate and uranium.[1, 3, 8,9,10]. A permeable reactive wall is constructed from appropriate treatment media (mixed with sand and) installed downgradient of a pollution source perpendicular to the groundwater flow direction to immobilise or degrade dissolved pollutants.[11] The mitigation effect on the pollutant has to be assured for the entire lifespan of the treatment system. The most commonly used reactive material is granular ZVI. ZVI walls are assumed to be active for several decades,[1, 3] even though the long-term reactivity of these materials is currently under investigation[12,13,14,15]

Objectives

Results

Conclusion