Zero-valent iron reactive materials for hazardous waste and inorganics removal

360 Pages·2006·19.733 MB·English

by  Irene M. C. Lo, Rao Surampalli & Keith C.K. Lai (Editors)

ZERO-VALENTIRON
REACTIVE MATERIALS FOR
HAZARDOUS WASTE AND
INORGANICS REMOVAL
SPONSORED BY
Hazardous, Toxic, and Radioactive Waste Management Committee
Environmental and Water Resources Institute (EWRI)
of the American Society of Civil Engineers
EDITED BY
Irene M. C. Lo
Rao Y. Surampalli
Keith C. K. Lai
ASCE
Published by the American Society of Civil Engineers
Library of Congress Cataloging-in-Publication Data
Zero-valent iron reactive materials for hazardous waste and inorganics removal / sponsored
by Hazardous, Toxic, and Radioactive Waste Management Committee, Environmental and
Water Resources Institute (EWRI) of the American Society of Civil Engineers ; edited by
Irene M. C. Lo, Rao Y. Surampalli, Keith C. K. Lai
p. cm.
Includes bibliographical references and index.
ISBN-13: 978-0-7844-0881-0
ISBN-10: 0-7844-0881-5
1. Groundwater—Purification. 2. Hazardous waste site remediation. 3. Membrane
separation. 4. Iron--Oxidation. 5. Ionic solutions. I. Lo, Irene Man-Chi. II.
Surampalli, Rao Y. III. Lai, Keith C. K. IV. Environmental and Water Resources Institute
(U.S.). Hazardous, Toxic, and Radioactive Waste Management Committee
TD426.Z42 2006
628.1 '68—dc22 2006028834
American Society of Civil Engineers
1801 Alexander Bell Drive
Reston, Virginia, 20191-4400
www.pubs.asce.org
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Copyright © 2007 by the American Society of Civil Engineers. All Rights Reserved.
ISBN 13: 978-0-7844-0881-0 ISBN 10: 0-7844-0881-5
Manufactured in the United States of America.
Preface
Zero-valent iron (Fe°) was first proposed as a reactive material for the removal
of chlorinated aliphatic hydrocarbons (CAHs) in groundwater in early 1990s. The
success of the corresponding laboratory experiments and the promising results from
the first field demonstration in mid 1990s showed the great potential of using Fe° for
groundwater remediation. This finding thereafter triggered the publication of a raft of
research papers related to the application of Fe° for the removal of other recalcitrant
hazardous wastes and inorganic contaminants, such as hexavalent chromium, nitrate
and arsenic etc, in water. Generally, Fe° is used as reactive media in permeable
reactive barrier (PRB) technology for groundwater remediation in which Fe° PRBs
are installed into subsurface to intercept the flow path of the contaminant plume.
Once the contaminated groundwater passively flows into the Fe° reactive media of the
PRBs, the contaminants are removed from the groundwater. After a decade of
scientific study and development, the maturity, credibility and applicability of the Fe°
PRB technology for hazardous waste and inorganic removal have been increased
substantially. Nowadays, Fe° PRBs have been widely recognized as an alternative to
groundwater remediation in addition to the conventional pump-and-treat system.
Despite of the fact that the operating principle of Fe° PRB technology is simple, its
design methodology is complicated. Furthermore, thorough understanding of the
hydraulic characteristic, geochemical behavior and reactivity of Fe°, and the involved
removal mechanisms is required so as to obtain good performance of Fe° for
contaminant removals. Primarily, this book is written to describe the mechanisms for
the removal of various hazardous wastes and inorganics by conventional Fe° and
innovative Fe°-based reactive materials, which aims to provide the engineers and
decision-makers an enough background to decide whether Fe° is cost-effective to be
applied in their sites for contaminant removals. Furthermore, this book discusses
some practical issues related to the design, construction and performance monitoring
of Fe° PRBs for providing engineers some technical solutions about the engineering
application of Fe for hazardous waste and inorganic removal.
Chapter 1 is the introductory chapter which describes the historical development of
Fe° and the advantages of Fe° PRBs over conventional pump-and-treat systems for
removal of hazardous wastes in groundwater, and the maximum contaminant level
(MCL) of various contaminants in groundwater and surface water. Section 1 (chapters
2 to 5) focuses on the removal of CAHs and hexavalent chromium using Fe° in which
chapter 2 compares the Fe° reactivity in the removal of CAHs between laboratory Fe°
column and a full-scale Fe° PRB. Chapters 3 and 4 address the simultaneous removal
of CAHs and hexavalent chromium in water. The former chapter studies the
application of a mixture Fe° and organo-clay for the removal of mixed contaminants,
whereas the latter chapter evaluates the competitive effect from other CAHs on the
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removal of trichloroethylene (TCE) or hexavalent chromium by Fe°. Chapter 5 gives
an in-depth review of the mechanism and reaction kinetics involved in the removal of
hexavalent chromium.
Section 2 (chapters 6 to 9) discusses the removal of aqueous nitrate and arsenic using
Fe°. Chapter 6 covers the fundamental study of the nitrate removal process by Fe°
including the effect of pH, Fe° dosage, nitrate concentration and humic acid etc on the
nitrate removal efficiency. Chapter 7 focuses on the application of clinoptilolite to
adsorb the byproduct (i.e., ammonium ion) generated during the nitrate removal
process by Fe°. Chapters 8 and 9 present the arsenic removal mechanism and kinetics
induced by Fe°, evaluate the influence of the presence of competing inorganic anions
on the arsenic removal efficiency, and discuss the mathematical model which is valid
to describe the arsenic removal process by Fe°.
Unlike sections 1 and 2 focusing on the contaminant removal processes using
conventional granular Fe° as reactive materials, section 3 (chapters 10 to 12) describes
the performance of various innovative Fe°-based reactive materials on the hazardous
waste removal, and the underlying theories and mechanisms involved. Chapter 10
compares the reactivity of conventional granular Fe° to that of the palladized granular
Fe° in the removal of TCE. Chapter 11 presents the complicated pathways involved in
the removal of halogenated methanes using nanoscale bimetallic palladized Fe°.
Chapter 12 evaluates the role of noble metal and Fe° in a bimetallic Fe° in the
removal of chlorinated hydrocarbons, and investigates the factors affecting the
reactivity of the bimetallic Fe°.
Section 4 (chapters 13 to 17) concerns the practical issues pertained to the design,
installation and performance monitoring of Fe° PRBs for groundwater remediation.
Chapter 13 presents the conventional and innovative configurations, and the
construction methods available for Fe° PRBs. On the other hand, chapter 14 describes
the methodology, such as treatability testing and hydrogeologic modeling, used to
design Fe° PRBs for hazardous waste and inorganic removal from groundwater.
Chapter 15 addresses the hydraulic issues of the Fe° PRBs associated with the
hydraulic characteris itniadceqsua toe fch agracrteariznatiuonl aofr p lFumee
t
hydrogeology, construction methods and geochemistry behavior of the Fe° PRBs.
Both chapters 16 and 17 focus on the evaluation of the performance of the full-scale
Fe° PRBs using the tracer experiment. The former chapter discusses the application of
reactive and conservative tracers in both natural gradient and forced gradient tracer
experiments to evaluate the hydraulic behavior and reactivity of the Fe° PRBs.
Chapter 17 gives a comprehensive description of the experimental method and theory
required for conducting a natural gradient tracer experiment to evaluate the flow
pattern of groundwater and groundwater velocity inside the Fe° reactive medium of
the PRBs.
iv
The efficacy and efficiency of the Fe° in the PRBs for contaminant removal are
enhanced because of the continuous advent of innovative Fe°-based reactive materials
and the increasing understanding of the factors affecting Fe° reactivity and the
relevant contaminant removal mechanisms. We hope that this book can give the
engineers, decision-makers and researchers an in-depth understanding of the
fundamental and environmental application of Fe° reactive materials for hazardous
waste and inorganic removal.
V
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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°-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°:
Full-Scale PRB vs Column Study 9
2.1 Introduction 9
2.2 Experimental Section 12
2.2.1 Full-scale Fe° 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
2.4.1 Longitudinal Dispersivity of the Fe° Packed Media 19
2.4.2 Influence of the Longitudinal Dispersivity on the CAH
Concentration along Fe° Packed Media 21
2.4.3 The Performance on CAH Dechlorination 23
2.4.4 A Factor of Safety for the Designed Fe° PRB Thickness 27
2.5 Conclusions 29
2.6 References 30
vii
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 3 6
3.2.2 Preparation of Organo-bentonite 3 6
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° 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
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
viii
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°/H SO System 81
2 4
6.3.1.1 Effect of pH 81
6.3.1.2 Effect of Fe° Dosage 82
6.3.1.3 Effect of Species with Hydroxyl Group 83
6.3.2 Fe°/C0 System 84
2
6.3.2.1 Effect of CO Bubbling 84
2
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
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
ix