title: An electrokinetic/Fe0 permeable reactive barrier system for the treatment of nitrate-contaminated subsurface soils.
abstract: Effective nitrate removal by Fe(0) permeable reactive barriers (Fe(0) PRB) has been recognized as a challenging task because the iron corrosion product foamed on Fe(0) hinders effective electron transfer from Fe(0) to surface-bound nitrate. The objectives of this study were (i) to demonstrate the effectiveness of an electrokinetic/Fe(0) PRB system for remediating nitrate-contaminated low permeability soils using a bench-scale system and (ii) to deepen the understanding of the behavior and fate of nitrate in the system. Bench-scale laboratory experiments were designed to investigate the influence of the Fe(0) content in the permeable reactive barrier, the pH in the anode well, and the applied voltage on remediation efficiency. The experimental results showed that the major reaction product of nitrate reduction by Fe(0) was ammonium and that nitrate reduction efficiency was significantly influenced by the variables investigated in this study. Nitrate reduction efficiency was enhanced by either increasing the Fe(0) content in the Fe(0) reactive barrier or decreasing the initial anode pH. However, nitrate reduction efficiency was reduced by increasing the applied voltage from 10 V to 40 V due to the insufficient reaction time during nitrate migration through the Fe(0) PRB. For all experimental conditions, nearly all nitrate nitrogen was recovered in either anode or cathode wells as nitrate or ammonium within 100 h, demonstrating the effectiveness of the system for remediating nitrate-contaminated subsurface soils.
authors.affiliation: Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan. tsuzuki@yamaguchi-u.ac.jp
authors.forename: Tasuma
authors.initials: T
authors.lastname: Suzuki
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Oyama
authors.forename: Mai
authors.initials: M
authors.lastname: Moribe
authors.forename: Masakazu
authors.initials: M
authors.lastname: Niinae
mesh_terms: D004560:Electricity; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D004787:Environmental Pollution / Q000032:analysis*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D006108:Graphite / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D009566:Nitrates / Q000032:analysis / Q000302:isolation & purification*; D009584:Nitrogen / Q000032:analysis; D010084:Oxidation-Reduction; D010539:Permeability; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000302:isolation & purification*
chemical_list: D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D012987:Soil; D012989:Soil Pollutants; D006108:Graphite; D007501:Iron; D009584:Nitrogen