Electrochemically Assisted Remediation of Contaminated Soils: Fundamentals, Technologies, Combined Processes and Pre-Pilot and Scale-Up Applications (Environmental Pollution, 30)

This book provides an overview of the current development status of remediation technologies involving electrochemical processes, which are used to clean up soils that are contaminated with different types of contaminants (organics, inorganics, metalloids and radioactive). Written by internationally recognized experts, it comprises 21 chapters describing the characteristics and theoretical foundations of various electrochemical applications of soil remediation. The book’s opening section discusses the fundamental properties and characteristics of the soil, which are essential to understand the processes that can most effectively remove organic and inorganic compounds. This part also focuses on the primary processes that contribute to the application of electrochemically assisted remediation, hydrodynamic aspects and kinetics of contaminants in the soil. It also reviews the techniques that have been developed for the treatment of contaminated soils using electrochemistry, and discusses different strategies used to enhance performance, the type of electrode and electrolyte, and the most important operating conditions. In turn, the book’s second part deals with practical applications of technologies related to the separation of pollutants from soil. Special emphasis is given to the characteristics of these technologies regarding transport of the contaminants and soil toxicity after treatment. The third part is dedicated to new technologies, including electrokinetic remediation and hybrid approaches, for the treatment of emerging contaminants by ex-situ and in-situ production of strong oxidant species used for soil remediation. It also discusses pre-pilot scale for soil treatment and the use of solar photovoltaic panels as an energy source for powering electrochemical systems, which can reduce both the investment and maintenance costs of electrochemically assisted processes. Preface Contents Part I: Fundamentals Physicochemical and Hydrodynamic Aspects of Soil 1 Introduction 2 Origin of Soils 3 Distribution of the Phases of a Soil 3.1 Phases of a Soil: Phase Diagram 3.2 Experimental Determination and Soil Phase Relations 4 The Solid Phase 4.1 Soil Mineralogy 4.2 Soil Texture 5 The Liquid Phase 5.1 Water 5.2 Solutes in the Liquid Phase 5.3 Electrical Conductivity 6 The Gas Phase 7 Coupled Hydromechanical Behavior of Soils 8 Flows in Soils 9 Conclusions References Fundamental of Electrokinetic Processes 1 Introduction 2 Electromigration 3 Electrophoresis 4 Electroosmosis 5 Applications of Electrokinetic Processes 6 Conclusions References Fundamental of Reactive and Thermal Processes in Electrochemically Assisted Soil Remediation 1 Introduction 2 Reactive Processes in Electrokinetic Soil Remediation: Electrolysis 3 Thermal Processes in Electrokinetic Soil Remediation: Electrical Heating 4 Development of Reactive and Thermal Processes in Electrokinetic Soil Remediation 5 Conclusion References Conceptual and Mathematical Modeling of the Transport of Pollutants in Soil by Electric Fields 1 Introduction 2 State of the Art 3 Numerical Evaluation of an EKR Process 3.1 Conceptual Model 3.1.1 Water Mass Balance 3.1.2 Chemical Species Mass Balance 3.1.3 Electric Charge Balance 3.1.4 Chemical Speciation 3.1.5 Mass Balance in Electrolyte Compartments 3.2 Numerical Model 3.3 Description of the Simulation Case 3.4 Simulation Results 3.4.1 Analysis of the Hydraulic Behavior 3.4.2 Analysis of Chemical Behavior 3.4.3 Analysis of Electrical Behavior 4 Conclusions References Part II: Technologies Treatment of Soil Washing Solutions by Electrochemical Advanced Oxidation 1 Introduction 2 EAOPs Involving Homogeneous Catalysis 2.1 Mechanisms of Electro-Fenton Process 2.2 Influence of Operating Parameters and Matrix Effects 3 EAOPs Involving Heterogeneous Catalysis 3.1 Electrode Materials 3.2 Technical Advantages Over Homogeneous Catalysis 3.3 Degradation and Mineralization Effectiveness 3.4 Electrooxidation Mechanisms 3.5 Selective Degradation of Soil Pollutants and SW Solution Reuse 4 Combination of Homogeneous and Heterogeneous Catalysis: Efficiency, Modeling, and Engineering Aspects 4.1 Efficiency of Combined Catalytic Processes 4.2 Charge Transfer vs Mass Transfer Competition 4.3 Reactor Design: Towards Transfer Intensification 5 Concluding Remarks References Electrokinetic Soil Flushing 1 Introduction 2 Basis of Electrokinetic Remediation 3 Removal of Organic Contaminants by Electrokinetics 4 Electrokinetic Removal of Soluble Organics 5 Electrokinetics with Co-solvents 6 Enhancing Solubility with Surfactants 7 Selective Complexation with Cyclodextrins 8 Polycyclic Aromatic Hydrocarbons 9 Chlorinated Aliphatic Hydrocarbons, Chlorophenols, and Chlorobenzenes 10 Herbicides and Pesticides 11 Nitroaromatic Compounds 12 Mixtures of Heavy Metals and Organic Pollutants 13 Coupled Electrokinetic-Chemical Oxidation/Reduction 14 Nanoparticle Transport by Electrokinetics 15 Coupled Electrokinetic-Permeable Reactive Barriers 15.1 Electrokinetic Bio-barriers 15.2 Reactive Electrolytic Barriers 16 Bioelectroremediation 17 Electric Amendment of Phytoremediation 18 Future Perspectives References Electrokinetic Remediation of Soil Polluted with Inorganic Ionic Species 1 Introduction 2 Fundamentals of Electrokinetic Remediation 3 Evolution of the Technology and Its Applications 3.1 Contamination by Complex Organic Compounds 3.2 Petroleum 3.3 Pesticides and Herbicides 4 Electrokinetic Removal of Heavy Metals 4.1 Electrokinetic Treatment of Complex Contaminations 4.2 Mathematical Modeling of Electrochemical Remediation 5 Conclusions References Fenton Processes for Remediation of Polluted Soils 1 Introduction 2 Influencing Parameters 2.1 Fenton Reagents Dosage 2.1.1 H2O2 Concentration 2.1.2 H2O2 Injection Point 2.1.3 Metal Content 2.1.4 Metal Addition 2.2 Types of Electrode Materials and Placement 2.3 Electric Field 2.4 pH Control and Electrolytes 2.5 Solubilizing and Stabilizer Agents 2.6 Soil Properties 3 Future Challenges 4 Conclusions References Coupling of Anodic Oxidation and Soil Remediation Processes 1 Introduction 2 Soil Remediation Processes 3 Coupling of SW/EKSR and Anodic Oxidation References Persulfate in Remediation of Soil and Groundwater Contaminated by Organic Compounds 1 Introduction 2 Thermal Activation of Persulfate (TAP) 3 Persulfate Activated by Transition Metals 4 Alkaline (Base) Activation of PS (BAP) 5 Persulfate Activation by Hydrogen Peroxide (HAP) 6 Conclusions References Electro-Phytoremediation of Cropland and Mine Tailings Polluted by Mercury, Using IrO2-Ta2O5/Ti Electrodes, Lavandula vera, and Solanum tuberosum 1 Introduction 2 Methodology 2.1 Phytoremediation of Soil with Lavandula vera 2.2 Phytoremediation of Soil with Solanum tuberosum 3 Discussion 3.1 Electro-Phytoremediation of Soil with Lavandula vera 3.2 Electro-Phytoremediation of Soil with Solanum tuberosum 4 Conclusion References Electrobioremediation of Polluted Soils 1 Bioremediation of Polluted Soil 2 Electrobioremediation of Polluted Soil. Concepts and Objectives 3 Microbial Transport and Activity Under Electrokinetics 4 Electrokinetic Biostimulation 4.1 pH Control into the Soil 4.2 Availability and Supply of Inorganic Nutrients and Electron Acceptors 4.3 Bioavailability of Nonpolar Pollutants. Surfactant Applications 5 Electrokinetic Bioaugmentation 6 Research Needs References The Soil and Groundwater Remediation with Zero-Valent Iron Nanoparticles 1 Introduction 2 The Zero-Valent Iron Nanoparticles 2.1 The Environmental Impact of the Use of Nanoparticles 3 The Tested Area Framework 3.1 Geologic and Hydrogeological Local Context 4 The Site Investigation 4.1 Baseline Situation: Soil Contaminants 4.2 Laboratory Evaluation on the nZVI Application Effectiveness 4.3 Site Injection Method and Monitoring 4.3.1 Definition of the Testing Areas 4.3.2 Instrumentation 4.4 The nZVI Application 4.4.1 Equipment 4.4.2 Dosage 4.4.3 Injection 4.4.4 Monitoring 4.4.5 Main Actions Calendar 4.5 Results 5 Conclusions References Adsorption and Ion Exchange Permeable Reactive Barriers 1 Introduction 2 Fundamentals of Permeable Reactive Barriers (PRBs) 3 Mechanism of Removal and Reactive Materials 4 Activated Carbon 5 Zeolite 6 Mixed Materials 7 Coupling PRBs and Electrokinetics for Soil Remediation 8 Pesticides 9 Petroleum 10 Inorganic Contaminants 11 Simultaneous Inorganic and Organic Remediation References Electrochemically Assisted Thermal-Based Technologies for Soil Remediation 1 Introduction 1.1 Non-electrochemical ISTR 1.2 Electrochemically-Assisted Thermal-Based Technologies 2 Additional Fundamentals of Electrothermal Techniques Reviewed and Mathematical Considerations 3 Applications and Setups 3.1 Selected Applications Showing the Impact of Electro-Thermal Effect 3.2 Observation of the Scale Effect 4 Real Case Studies and Companies in the Sector 5 Conclusions References Electrochemically Assisted Dewatering 1 Introduction 2 Discussion 2.1 Electrochemical Transport Processes 2.2 Principles of Electro-osmosis 2.2.1 Double Diffuse Layer 2.2.2 Theory of Helmholtz–Smoluchowski 2.3 Electro-osmosis Setup in Field Applications 2.3.1 Experimental Operation Conditions 2.4 Applications 2.4.1 Consolidation of Fine-Grained Matrices 2.4.2 Removal of Contaminants 2.4.3 Other Matrices 3 Conclusion References Part III: Scale-up Fundamentals of the Scale-Up of the Electrochemically Assisted Soil Remediation Processes 1 Introduction 2 From Lab Scale to Full Application: Main Aims and Cell Design 3 Technological Outcomes 4 Conclusions References Electrochemical Technologies for Petroleum Contaminated Soils 1 Introduction and Background 2 Electrokinetic Extraction and Recovery 2.1 Extraction/Treatment of VOCs, PAHs, and Organic Acids 2.2 Extraction of Crude Oil 2.3 Laboratory Evidence of Crude Oil Transport by Water Displacement 3 Electrokinetically Enhanced Transformations 3.1 Evidence of Transformation of Inorganic Compounds 3.2 Evidence of Transformation of Crude Oil 4 Summary and Conclusions References Treatment of Gaseous Effluents Produced During Electrochemically Assisted Soil Remediation Processes 1 Introduction 2 Generation of Gaseous Effluents by Electrochemically Assisted Soil Remediation Processes 3 Treatment of Gaseous Effluents Generated by Soil Remediation Processes 3.1 Adsorption 3.2 Thermal and Catalytic Oxidation Processes 3.3 Absorption 3.4 Other Processes 4 Comparison Between Treatment Processes and Final Considerations References Solar-Powered Electrokinetic Remediation for Treatment to Soil Polluted with Organic Compounds 1 Introduction 2 Basic Principles and Main Characteristics of the Electroremediation 3 Use of Photovoltaic Panels in Electrochemical Processes 3.1 Performance of a Photovoltaic Panel 3.2 Use of Photovoltaic Panels in Electrochemical Processes 3.3 State of the Art of Photovoltaic Solar Powered Electroremediation 4 Design of a Real Electroremediation System Supplied with Photovoltaic Panels 4.1 General Considerations 4.1.1 Electroremediation System Directly Supplied with a Photovoltaic Solar Plant 4.2 Design Choices for ERem-PV Systems. Examples Based on a Real Case 4.2.1 ERem-PV System Without Batteries 4.2.2 ERem-PV System with a Battery Pack 4.2.3 Comparison Between ERem-PV Systems Without and with a Pack of Batteries References Electrokinetic Processes: Directions for Future Research and Constraints 1 Introduction 2 Factors Affecting EKR Technology 2.1 Soil Condition 2.2 Designing the Electrokinetic System 2.3 Advantages and Disadvantages of EKR Technology 2.4 Electrokinetic Removal of Heavy Metals in Field-Scale Tests 2.5 Electrokinetic Remediation of Organic Pollutants from Contaminated Soils 3 Integrated Remediation Technologies 4 Research and Directions for Future Research on Electrokinetic Remediation 5 Conclusion References Index