Title: Permeable Reactive Barrier for uranium contaminated groundwater 
Resource Type: document --> technical publication --> methodology description 
Country: Hungary 
Year: 2005 
Availability: In: K.E. Roehl, T. Meggyes, F.-G. Simon and D.I. Stuart: Long-term Performance of Permeable Reactive Barriers. ELSEVIER, 2005 
Author 1/Producer: Mihály Csõvári 
Author / Producer Type: Consultancy, contractor or other service provider 
Publisher: Elsevier 
EUGRIS Keyword(s): Contaminated land-->Contaminated land overview
Contaminated land-->Remediation options-->Permeable reactive barriers
Contaminated land-->Remediation options-->Remediation options overview
 
Short description: The site-results demonstrate the practical usability of the permeable reactive barriers for remediation of the uranium-contaminated groundwater 
Long description: The used groundwater remediation technology is based on the reduction of uranium from six-valent form into four-valent form with metallic iron. The reduced form of uranium precipitates (because of lower solubility) and remains in the barrier. Beside this principal process the iron reacts with the other constituents of the water. The result of these reactions is the increasing of the pH of water and the substantial decreasing of the TDS of water and as a result the formation of precipitate. The formed precipitate can block the reactivity of the barrier after some years. The goal of the project is the monitoring of the long-term performance of the permeable reactive barriers using zero valent iron. The permeable reactive barrier consists of four separate layers: Role of the layers: 1st layer: upstream water distributing layer on the entering into the barrier (sand) 0.5 m; 2nd layer: 1st reactive zone for removing of the oxygen from the entering groundwater. Iron content in the mixture:0.38 t/m3, width: 0.5 m; 3rd layer: 2nd reactive zone with high iron content (1.27 t/m3 ) in the mixture, width: 1.0 m; 4th layer: downstream water distributing layer (sand) 0.5 m. The remedial strategy adopted for the work comprised the following: • Phase I – Baseline groundwater monitoring, • Phase II – Laboratory, pilot-scale test and small-scale field test for characterisation selection of reactive material, • Phase III – Excavation of the needed trench, · Phase IV Placing the reactive mixture (mixture of iron and sand), • Phase V – Building of groundwater monitoring system, · Phase VI – Ongoing monitoring. Water from monitoring wells are sampled periodically usually on half-year basis and analysed for macro constituents (SO4, HCO3, Cl, Na, K, Ca, Mg, TDS) and trace elements by ICP, and of course for uranium and Ra. Up to now the reactive barrier is highly effective for removing of uranium. The efficiency in the barrier is >95-99 %. 
Submitted By: Dr Katalin Gruiz WhoDoesWhat?      Last update: 14/02/2006