Zero-Valent Iron Reactive Materials for Hazardous Waste and Inorganics Removal Table of Contents Chapter 1 Introduction 1 1.1 Historical Development of Zero-Valent Iron for Hazardous Waste Removal 1 1.2 Groundwater and Surface Water Standards 2 1.3 Comparison of the Fe 0 -Based Permeable Reactive Barriers and Pump-and-Treat Systems in Hazardous Waste Removal 5 1.4 References 6 Section I Removals of Chlorinated Aliphatic Hydrocarbons and Hexavalent Chromium Using Zero-Valent Iron Chapter 2 Removals of Chlorinated Aliphatic Hydrocarbons by Fe 0 : Full-Scale PRB vs Column Study 9 2.1 Introduction 9 2.2 Experimental Section 12 2.2.1 Full-scale Fe 0 PRB Installed at Vapokon Site, Denmark 12 2.2.2 Laboratory Column Experiment 12 2.2.3 Groundwater Sample Measurements 16 2.3 Data Analysis 16 2.3.1 Determination of Longitudinal Dispersivity 16 2.3.2 Calculation of the Observed First-order Dechlorination Rate Constant 17 2.4 Results and Discussion 19 i
2.4.1 Longitudinal Dispersivity of the Fe 0 Packed Media 19 2.4.2 Influence of the Longitudinal Dispersivity on the CAH Concentration along Fe 0 Packed Media 21 2.4.3 The Performance on CAH Dechlorination 23 2.4.4 A Factor of Safety for the Designed Fe 0 PRB Thickness 27 2.5 Conclusions 29 2.6 References 30 Chapter 3 Zero-Valent Iron and Organo-Clay for Chromate Removal in the Presence of Trichloroethylene 35 3.1 Introduction 35 3.2 Experimental Section 36 3.2.1 Materials and Their Characterization Methods 36 3.2.2 Preparation of Organo-bentonite 36 3.2.3 Column Experiments 37 3.2.4 Data Analysis 38 3.3 Results and Discussion 39 3.4 Conclusions 45 3.5 References 45 Chapter 4 Competitive Effects on the Dechlorination of Chlorinated Aliphatic Hydrocarbons by Zero-Valent Iron 47 4.1 Introduction 48 4.2 Materials and Methods 49 4.2.1 Materials 49 4.2.2 Experimental Methods 50 4.2.3 Data Analysis 51 4.3 Results and Discussion 52 4.3.1 Dechlorination of CAHs by Fe 0 52 4.3.2 Competition between TCE and 1,1,1-TCA 52 4.3.3 Competition among TCE, 1,1,1-TCA and TCM at Various Temperatures 54 4.3.4 Competition between TCE and Cr(VI) 55 ii
4.4 Conclusions 58 4.5 References 58 Chapter 5 Removal of Hexavalent Chromium from Groundwater Using Zero-Valent Iron Media 61 5.1 Introduction 61 5.2 Removal Mechanisms 62 5.3 Reaction Kinetics 63 5.4 Other In Situ Cr(VI) Removal Methods 69 5.5 Case Studies 70 5.5.1 Elizabeth City, North Carolina 70 5.5.2 Kolding, Denmark 72 5.6 Conclusions 72 5.7 References 73 Section II Removals of Nitrate and Arsenic using Zero-valent Iron Chapter 6 Aqueous Nitrate Reduction by Zero-Valent Iron Powder 77 6.1 Introduction 77 6.2 Experimental Section 79 6.2.1 Material and Reagents 79 6.2.2 Reaction Systems and Operation 80 6.2.3 Instrumental Analyses 80 6.3 Results and Discussion 81 6.3.1 Fe 0 /H 2 SO 4 System 81 6.3.1.1 Effect of ph 81 6.3.1.2 Effect of Fe 0 Dosage 82 6.3.1.3 Effect of Species with Hydroxyl Group 83 6.3.2 Fe 0 /CO 2 System 84 6.3.2.1 Effect of CO 2 Bubbling 84 6.3.2.2 Effect of Initial Nitrate Concentration 85 6.3.2.3 Effect of Humic Acid 86 6.3.2.4 Effect of Cations and Anions 87 iii
6.3.2.5 Effect of Operating Modes 89 6.3.3 Issue of Undesired Byproducts and its Resolution 90 6.4 Conclusions and Recommendations 92 6.5 References 93 Chapter 7 Removal of Nitrate from Water by a Combination of Metallic Iron Reduction and Clinoptilolite Ion Exchange Process 95 7.1 Introduction 95 7.2 Materials and Methods 98 7.2.1 Chemicals 98 7.2.2 Nitrate Reduction Experiments 98 7.2.3 Ion Exchange Experiments 99 7.3 Results and Discussions 100 7.3.1 Effect of ph 100 7.3.2 Effect of Nitrate Loading 101 7.3.3 Overall Nitrate Reduction Efficiency 103 7.3.4 Removal of Ammonia in the Presence of Fe(II) Ions 104 7.4 Summary 107 7.5 References 107 Chapter 8 Utilization of Zero-Valent Iron for Arsenic Removal from Groundwater and Wastewater 111 8.1 Introduction 111 8.2 Batch Tests with Non Mine-Impacted Waters 114 8.3 Batch Test with Acid Mine Drainage 121 8.4 Effects of Competing Inorganic Anions on Arsenic Removal by Zero-Valent Iron 122 8.5 Column Tests and Field Applications 127 8.6 Mechanisms of Arsenic Removal by Zero-Valent Iron 131 8.7 Alternative Materials of Iron and Aluminum Oxides for Arsenic Removal 140 8.8 Knowledge Gaps and Research Needs 141 8.9 Conclusions 142 8.10 References 143 iv
Chapter 9 Removal of Arsenic from Groundwater Mechanisms, Kinetics, Field/Pilot and Modeling Studies 151 9.1 Introduction 151 9.2 Mechanism of Removal and Competing Ion Effects 154 9.3 Field/Pilot Studies and Modeling 157 9.4 Design Considerations 163 9.5 Conclusions 164 9.6 References 164 Section III Innovative Iron-based Reactive Materials Chapter 10 The Performance of Palladized Granular Iron: Enhancement and Deactivation 172 10.1 Introduction 173 10.2 Experimental Section 174 10.2.1 Chemicals and Materials 174 10.2.2 Column Tests 175 10.2.3 Chemical Analyses 175 10.2.4 Auger Electron Spectroscopy (AES) 176 10.2.5 X-Ray Photoelectron Spectroscopy (XPS) 176 10.3 Results and Discussion 176 10.3.1 Pd Plating Efficiency 176 10.3.2 Column Tests 177 10.3.3 Surface Analysis 180 10.4 Conclusions 184 10.5 References 185 Chapter 11 Nanoscale Bimetallic Pd/Fe Particles for Remediation of Halogenated Methanes 187 11.1 Introduction 187 11.2 Experimental Section 191 11.2.1 Batch Experiments 191 11.2.2 Headspace Analysis 191 v
11.2.3 Kinetic Analysis 191 11.2.4 Materials and Chemicals 192 11.3 Results 192 11.3.1 Product Distributions and Reaction Rates 192 11.3.2 Correlation Analysis 194 11.3.3 Kinetic Simulation 196 11.4 Discussion 201 11.5 Conclusions 203 11.6 References 203 Chapter 12 Reduction by Bimetallic Reactive Materials Containing Zero-Valent Iron 206 12.1 Introduction 206 12.2 Noble Metals as Reduction Catalysts 207 12.3 Preparation of Bimetallic Reductants 209 12.4 Reduction Reactions of Bimetallic Materials 210 12.4.1 Direct Adsorption of Atomic Hydrogen 211 12.4.2 Dissociative Adsorption of Diatomic Hydrogen 213 12.4.3 Roles of Iron as the Primary Metal 213 12.5 Factors Affecting Reaction of Bimetallic Reductants 215 12.5.1 Effect of the Type of Noble Metal 215 12.5.2 Effect of Noble Metal Content and Surface Area 215 12.5.3 Effect of Solution Chemistry 216 12.6 Deactivation of Bimetallic Reductants 216 12.7 Nano-sized Bimetallic Reductants 217 12.8 Conclusions 218 12.9 References 218 Section IV Zero-Valent Iron Reactive Barrier: Configuration, Construction, Design Methodology, and Hydraulic Performance Chapter 13 Configuration and Construction of Zero-Valent Iron Reactive Barriers 224 vi
13.1 Introduction 224 13.2 Permeable Reactive Barrier Configurations 225 13.2.1 Continuous Permeable Reactive Barriers 226 13.2.2 Funnel-and-gate Permeable Reactive Barriers 226 13.2.3 Caisson Permeable Reactive Barriers 227 13.2.4 Trench Permeable Reactive Barriers 228 13.2.5 GeoSiphon TM /GeoFlow 228 13.3 Emplacement Techniques for Permeable Reactive Barriers 229 13.3.1 Emplacement Techniques for Permeable Treatment Zone 230 13.3.1.1 Trench Excavation 230 13.3.1.2 Caisson-Based Emplacement 231 13.3.1.3 Mandrel-Based Emplacement 231 13.3.1.4 Continuous Trenching 232 13.3.2 Emplacement Techniques for Impermeable Funnels 232 13.3.2.1 Steel Sheet Piling 232 13.3.2.2 Slurry Wall 233 13.3.3 Innovative Technologies for the Emplacement of Permeable Treatment Zone and Impermeable Funnels 233 13.3.3.1 Jetting 234 13.3.3.2 Hydraulic Fracturing 234 13.3.3.3 Deep Soil Mixing 234 13.4 Case Studies 235 13.4.1 Configuration and Construction of a Permeable Reactive Barrier at Vapokon Site, Denmark 235 13.4.2 Configuration and Construction of a Permeable Reactive Barrier at United States Coast Guard (USCG) Support Centre in Elizabeth City, North Carolina 237 13.4.3 Configuration and Construction of a Permeable Reactive Barrier at an Industrial Site in Belfast, Northern Ireland 238 13.5 Summary 239 13.6 References 239 Chapter 14 Design Methodology for the Application of a Permeable vii
Reactive Barrier for Groundwater Remediation 243 14.1 Introduction 243 14.2 Preliminary Assessment 245 14.3 Site Characterization 247 14.4 Reactive Media Selection 247 14.5 Treatability Testing 250 14.6 Hydrogeologic and Geochemical Modelings 254 14.7 Monitoring Plan 257 14.8 Permeable Reactive Barrier Economics 259 14.9 Summary 261 14.10 References 261 Chapter 15 Hydraulic Issues Related to Granular Iron Permeable Reactive Barriers 267 15.1 Introduction 267 15.2 Hydraulic Characteristics of Granular Iron and Impact on PRB Design 268 15.3 Influence of Inadequate Characterization of Plume Hydrogeology on Hydraulic Performance 271 15.4 Influence of Construction Methods on Hydraulic Performance 272 15.5 Influence of Long-Term Geochemical Changes on Hydraulic Performance 275 15.6 Summary 278 15.7 References 278 Chapter 16 Tracer Experiments in Zero-Valent Iron Permeable Reactive Barriers 282 16.1 Introduction 282 16.2 Tracer Experiments in Laboratory Columns 285 16.3 Tracer Experiments at PRB Sites 289 16.3.1 Rheine Site PRB 291 16.3.2 Tübingen Site PRB 294 16.4 Conclusions 300 viii
16.5 References 301 Chapter 17 Hydraulic Studies of Zero-Valent Iron in Permeable Reactive Barriers Using Tracer Experiment 309 17.1 Introduction 309 17.2 Vapokon Site Description and Fe 0 PRB Emplacement 311 17.3 Natural Gradient Tracer Experiment for the Hydraulic Performance Monitoring of the Fe 0 PRB at Vapokon Site 312 17.3.1 Selection of Suitable Tracer Materials 312 17.3.2 Groundwater Modeling 314 17.3.2.1 Design Parameters for the Tracer Injection System 314 17.3.2.2 Design Parameters for the Groundwater Sampling System 315 17.3.2.3 Groundwater Flow Model and Solute Transport Program 316 17.3.3 Injection Wells and System 317 17.3.4 Groundwater Sampling Network and Systems 320 17.3.5 Collection of Groundwater Samples and Chemical Analysis of Tracers 320 17.3.6 Data Analysis Spatial Moments Analysis for the Lithium Plume 322 17.4 Results and Discussion 324 17.4.1 Flow Pattern of the Lithium Plume 324 17.4.2 Breakthrough Curves of Bromide 328 17.4.3 Mass of Lithium Flowing through the Fe 0 Reactive Medium 329 17.4.4 Groundwater Velocity 331 17.5 Conclusions 331 17.6 References 332 Appendix 337 Subject Index 339 ix