EPA/600/R-94/202
November 1994
CONTAMINANTS AND REMEDIAL OPTIONS AT
PESTICIDE SITES
Rajeshmal Singhvi
U.S. Environmental Protection Agency
Environmental Response: Team
Edison, NJ 08837-3(579
Richard N. Koustas
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
Edison, NJ 08837-3(379
and
Michael Mohn
Roy F. Weston, Inc.
Edison, NJ 08837-3(379
Contract # 68-03-3482
Project Officer
Richard N. Koustas
Technical Support Branch
Superfund Technology Demonstration Division
Edison, NJ 08837
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
Printed on Recycled Paper
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NOTICE
The information in this document has been funded wholly or in part by the United SStates Environmental
Protection Agency (EPA or the Agency) under contract 68-C4-0022 to Roy F. Weston, Inc. It has been
subjected to the Agency's peer and administrative review, and it has been approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
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FOREWORD
Today's rapidly developing and changing technologies and industrial products and practices frequently carry
with them the increased generation of materials that, if improperly dealt with, can threaten both public health
and the environment. The U.S. Environmental Protection Agency (EPA or the Agency) is charged by Congress
with protecting the nation's land, air, and water resources. Under a mandate of national environmental laws,
the Agency strives to formulate and implement actions leading to a compatible balance between human
activities and the ability of natural resources to support and nurture life. These laws direct EPA to perform
research to define our environmental problems, measure the impacts, and search for solutions.
The Risk Reduction Engineering Laboratory (RREL) is responsible for planning, implementing, and managing
research, development, and demonstration programs to provide an authoritative, defensible engineering basis
in support of the policies, programs, and. regulations of EPA with respect to drinking water, wastewater,
pesticides, toxic substances, solid and hazardous wastes, and Siuperfund-related activities. This publication
is one of the products of that research and provides a vital communication link between the researcher and
the user community.
This document provides information specific to pesticide sites to assist federal and state remedial project
managers (RPMs), potentially responsible parties (PRPs), and remedial contractors in identifying remedial
options, planning, developing treatment systems, and implementing remedies at,sites contaminated with
pesticides. It is intended to facilitate remedy selection and to accelerate cleanup at these sites.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
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ABSTRACT
This document provides information that facilitates treatment technologies and services selection at pesticide
sites in order to meet the acceptable levels of cleanliness stipulated in applicable regulations. It does not
provide risk-assessment information or policy guidance related to the determination of cleanup levels. It will
assist federal, state, or private site removal and remedial managers operating under Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA), Resource Conservation and Recovery
Act (RCRA), or state rules.
Pesticide contamination results from manufacturing, improper storage, handling, or disposal, and/or agricultural
processes and includes a wide variety of compounds. It can occur in soil, sediment, and sludge and lead to
secondary contamination of underlying soils and groundwater pollution. Remediation of pesticide wastes is
complicated since most pesticides are mixtures of different compounds.
The remedial manager faces the challenge of selecting remedial options that meet established cleanup levels.
The principal options are immobilization, destruction, and separation/concentration. Separation/concentration
technologies prepare contaminated media for further remediation by reducing their volume. A treatment train
is another technique that is widely used and exists when more than one technology, including pre- and post-
treatment components, is implemented for a pesticide site's remediation strategy.
This document is designed for use with other remedial guidance documents issued for RCRA, CERCLA, and/or
other state mandated cleanups to accelerate the remediation of pesticide sites. Section 1 provides an
introduction to the document and its organization and contains considerations for the selection of a remediation
strategy. Section 2, Contaminants at Pesticide Sites, identifies the sources and types of pesticide
contaminants, characterizes them, and describes their behavior in the environment.
Section 3, Remedial Options, covers innovative and emerging technologies, and proven treatments; it includes
discussion about the status of implementation of a technology and its selection for cleanup at Superfund sites.
The technology performance data provided can assist the remedial manager in narrowing options to those
most likely to succeed in achieving site-specific cleanup goals. Treatment trains are explained and examples
are included in this section to emphasize their importance to the remedial strategy.
This report was submitted in fulfillment of Contract No. 68-C4-0022 by Roy F. Weston, Inc. under the
sponsorship of the U.S. Environmental Protection Agency.
IV
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CONTENTS
Notice ,. ii
Foreword iii
Abstract iv
Figures vii
Tables .... viii
Abbreviations x
Acronyms xi
Acknowledgments — xii
Section 1. INTRODUCTION ..... 1
Purpose 1
Organization 1
Essential References and Sources of Information 1
Policy 1
Technical 1
Remediation Strategy and Selection of Options 3
Considerations for Cost Estimation 6
References for Section 1 7
Section 2. CONTAMINANTS AT PESTICIDE SITES '. 10
Introduction 10
Historical Use of Pesticides 10
Regulation of Pesticides ..: 10
Pesticide Chemicals ". , 11
Sources of Contamination at Pesticide Sites 15
Contaminant Behavior, Fate, and Transport 15
Predicting Contaminant Behavior 15
Chemical Formulation and Its Influence on Pesticide Toxicity,
Migration, and Transformation 17
Chemical Structure 17
Pesticide Concentration 17
Formulations and Carriers 18
Surfactants 19
Contaminant Behavior Related to Waste Groups 19
Inorganics (WG01) 19
Halogenated Water Insoluble Organics (WG02) 19
Halogenated Sparingly Water Soluble Organics and
Organo-Linked Compounds (WG03) 20
Nonhalogenated Organics and Organo-Linked
Compounds (WG04) 20
References for Section 2 20
Section 3. REMEDIAL OPTIONS 22
Introduction 22
Immobilization Options 25
Containment Technologies 25
Capping Systems 25
Vertical Barriers 27
Horizontal Barriers .29
Stabilization/Solidification Technologies 30
Applicability 30
Vitrification Technologies 34
Applicability 35
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CONTENTS (Continued)
Section 3. (Continued)
Destruction Options 36
Thermal Destruction Technologies 37
Incineration 37
Ultra High Temperature Process 40
Chemical Destruction Technologies 41
Chemical Oxidation 41
Dehalogenation/Hydrodehalogenation 44
Hydroprocessing/Heteroatom Removal 48
Hydrolysis/Neutralization 49
Biological Destruction Technologies 51
Bioremediation/Microbial Degradation 51
Separation/Concentration Options 56
In-Situ Separation/Concentration Technologies 57
Soil Flushing 57
Soil Vapor Extraction (SVE) 60
Steam Extraction 61
Radio Frequency Heating 63
Ex-Situ Separation/Concentration Technologies 65
Soil Washing 65
Thermal Desorption 68
Solvent Extraction 71
Treatment Technology Options for Contaminated Groundwater 74
Destruction Technologies 75
Chemical Oxidation 75
Chemical Reduction 77
Hydrolysis/Neutralization 79
Bioremediation 81
Separation/Concentration Technologies 83
Adsorption 83
Filtration 85
Ion Exchange 86
Evaporation 87
Summary : 89
References for Section 3 89
Appendix A TABLES 96
VI
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FIGURES
Number
PAGE
1-1
3-1 a
3-1 b
3-1 c
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
3-11
3-12
3-13
3-14
3-15
3-16
3-17
3-18
3-19
Effect of Site Size on Incinerator Cost 7
Conceptual Presentation of Remedial Options for Soil and Sediment 23
Conceptual Presentation of Remedial Options for Soils and Sediment 24
Conceptual Presentation of Remedial Options for Soils and Sediment 24
Schematic for Incineration of Pesticide-Contaminated Soils,
Sediments, and Sludges 39
Schematic for Chemical Oxidation (Ex-Situ) of Pesticide-Contaminated Soils,
Sediments, and Sludges Using Ozone and UV 43
Schematic for Dehalogenation (Ex-Situ) of Pesticide-Contaminated Soils,
Sediments, and Sludges 47
Schematic for Hydrolysis/Neutralization (In-Situ) of Pesticide-Contaminated Soils 50
Schematic for Slurry-Phase Bioremediation (Ex-Situ) for Pesticide-Contaminated
Soils, Sediments, and Sludges 52
Schematic for In-Situ Bioremediation Using Injection
for Pesticide-Contaminated Soils 53
Schematic for Soil Flushing (In-Situ) of Pesticide-Contaminated Soils 58
Schematic for Steam Extraction (In-Situ) of Pesticide-Contaminated Soils 62
Schematic for Soil Washing of Pesticide-Contaminated
Soils, Sediments, and Sludges .67
Schematic for Thermal Desorption (Ex-Situ) of Pesticide-Contaminated Soils,
Sediments, and Sludges .. 70
Schematic for Solvent Extraction (Ex-Situ) of Pesticides from Contaminated
Soils, Sediments, and Sludges 73
Schematic for Chemical Oxidation of Pesticide-Contaminated Groundwater 76
Schematic for Chemical Reduction of Pesticide-Contaminated Groundwater 78
Schematic for Hydrolysis/Neutralization (In-Situ) of Pesticide-Contaminated
Groundwater 80
Schematic for Bioremediation (In-Situ) of Pesticide-Contaminated Groundwater 82
Schematic for Carbon Adsorption of Pesticide-Contaminated Groundwater 84
Schematic for Filtration of Pesticide-Contaminated Groundwater 85
Schematic for Evaporation of Pesticide-Contaminated Groundwater 88
VII
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TABLES
Number PAGE
2-1 Distribution Among Pesticide Products 10
2-2 Pesticide Chemical Waste Groups 13
2-3 Pesticide Contamination Sources 15
3-1 Treatment Trains with Innovative Treatment Technologies in Superfuncl
Remedial Actions 23
3-2 Typical Cost Considerations - Caps 26
3-3 Data Needs for Capping Alternatives 27
3-4 Typical Cost Considerations - Vertical Barriers 28
3-5 Vertical Barriers Data Needs 29
3-6 Data Needs for Horizontal Barriers 30
3-7 Stabilization/Solidification Technology Used at the Velsicol Chemical Site 32
3-8 Treatability Test Results for S/S Treatment of RCRA Metals 33
3-9 Data Needs for Solidification/Stabilization Treatment 34
3-10 Pesticide Destruction/Removal Efficiencies Using ISV 35
3-11 Performance Data on In-Situ Vitrification 35
3-12 Data Needs for In-Situ Vitrification Technologies 36
3-13 Incineration Destruction Results 38
3-14 Data Needs for Incineration 40
3-15 Reductions in Pesticide Levels Achieved Using Oxidation Methods 42
3-16 Effect of UV Oxidation on Carbofuran and Malathion 42
3-17 Data Needs for Chemical Oxidation 44
3-18 Hydrodechlorination Results 45
3-19 Data Needs for Dehalogenation/Hydrodehalogenation 47
3-20 Data Needs for Hydroprocessing 49
3-21 Results from Hydrolysis Treatment of Pesticide-Contaminated Soil 49
3-22 Data Needs for Hydrolysis/Neutralization 51
3-23 Results from Bioremediation Tests When Used to Treat
Pesticide-Contaminated Soils 54
3-24 Bioremediation Cost Ranges 55
3-25 Data Needs for Bioremediation 55
3-26 Data Needs for Soil Flushing 59
3-27 Data Needs for Soil Vapor Extraction 61
3-28 Results of Pilot Test Program at Rocky Mountain Arsenal 63
3-29 Data Needs for RF Heating 65
3-30 Soil Washing Remediation at Four Superfund Sites 66
3-31 Data Needs for Soil Washing 67
3-32 Results of LTTA Thermal Desorption Study 69
3-33 Data Needs for Thermal Desorption 71
3-34 RCC B.E.S.T. Treated Pesticide-Contaminated Soil - Bench Scale 72
3-35 Results from Solvent Extraction Tests 72
3-36 Data Needs for Solvent Extraction 74
3-37 Typical Treatment Combinations and Trains for Pesticide-Contaminated Water 75
3-38 Results of Chemical Oxidation Treatment 76
3-39 Data Needs for Chemical Oxidation 77
3-40 Data Needs for Chemical Reduction ,79
VIII
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TABLES (Continued)
Number
3-41
3-42
3-43
3-44
3-45
3-46
PAGE
Data Needs for Hydrolysis/Neutralization
Data Needs for Bioremediation
Data Needs for Adsorption
Data Needs for Filtration
Data Needs for Ion Exchange
Data Needs for Vaporization
80
82
84
86
87
88
IX
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ABBREVIATIONS
Al
APEG
BNAs
CEC
CPE
ODD
DDE
DDT
DMSO
EC
EDB
ETU
FML
ft2
GAG
HOPE
KPEG
Ib
LDPE
LTTA
MCL
MCPA
NAPL
O&M
PAC
PAH
PCB
PGP
PEG
ppb
ppm
PVC
SOM
S/S
TCDD
UV
VOCs
WP
yd3
active ingredient
alkaline metal hydroxide/polyethylene glycol
base/neutral acid extractables
cation exchange capacity
chlorinated polyethylene
dichlorodiphenyldichloroethane
dichlorodiphenyidichloroethylene
dichlorodiphenyltrichloroethane
dimethyl sulphoxide
emulsifiable concentrates
ethylene dibromide
ethylenethiourea
flexible membrane liner
square feet
granular activated carbon
high density polyethylene
potassium hydroxide/polyethylene glycol
pound
low density polyethylene
low temperature thermal aeration
maximum contaminant levels
2-methyl-4-chlorophenoxyaceticacid
nonaqueous phase liquid
operations and maintenance
powder activated carbon
polyaromatic hydrocarbons
polychlorinated biphenyls
pentachlorophenol
polyethylene glycol
parts per billion
parts per million
polyvinyl chloride
soil organic matter
solidification/stabilization
2,3,7,8-tetrachlorodibezo-o-dioxin
ultraviolet
volatile organic compounds
wettable powders
cubic yard
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ACRONYMS
B.E.S.T. Basic Extractive Sludge Treatment (a process patented by RCC)
BOAT Best Demonstrated Available Technology
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CWS Community Water System
POD Department of Defense
DOE Department of Energy '
DOI Department of Interior
EPA U.S. Environmental Protection Agency
ERT Environmental Response Team
FIFRA Federal Insecticide, Fungicide, and Rodenticide Act
MTG Minimum Technical Guidance
NJDEPE New Jersey Department of Environmental Protection and Energy
NPL National Priorities List
NSH Nascent State Hydrodechlorination
NTIS National Technical Information Service
ODW Office of Drinking Water (within EPA)
OERR Office of Emergency and Remedial Response
OPP Office of Pesticide Program (within EPA)
ORD Office of Research and Development
POTW Publicly-Owned Treatment Works
PRPs Potentially Responsible Parties
RCRA Resource Conservation and Recovery Act
RFI RCRA Facility Investigation (Guidance)
RI/FS Remedial Investigation/Feasibility Study
ROD Records of Decision
RPM(s) Remedial Project Manger(s)
RREL Risk Reduction Engineering Laboratory
S/S Stabilization and Solidification
SDWA State Drinking Water Act
SITE Superfund Innovative Technology Evaluation
SVE Soil Vapor Extraction
TCLP Toxicity Characteristic Leaching Procedure
TSD Treatment, Storage, and Disposal
TWA Treatment Work Approval
USAGE U.S. Army Corps of Engineers
VISITT Vendor Information System for Innovative Treatment
XI
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ACKNOWLEDGMENTS
This reference is the product of a cooperative effort between the U.S. Environmental Protection Agency
(EPA) Office of Emergency and Remedial Response (OERR) and the Office of Research and Development
(ORD). Roy F. Weston, Inc. (WESTON®) prepared the text under EPA Contract No. 68-C4-0022. The EPA
Work Assignment Manager was Richard Koustas of the Risk Reduction Engineering Laboratory (RREL)
Technical Assistance Section, Superfund Technology Demonstration Division. Gregg Beatty served as the
WESTON Project Leader. Stephen Smith and Anuj Saha, P.E., were the original authors. Larry Lin, Ph.D.,
P.E., Nicole Adaniya, and Michael Mohn were the co-authors, and Laura A. Barletta incorporated review
comments and performed technical editing for the final report.
The authors express their appreciation to the following persons who contributed to portions of major
sections: John Matthews of the Robert S. Kerr Environmental Research Laboratory (Contaminants at
Pesticide Sites), Ada, Oklahoma, and Robert Landreth, Patricia Erickson, and Carlton Wiles of RREL
(Immobilization Options).
Special recognition is extended to the Tennessee Valley Authority (TVA) National Fertilizer and
Environmental Research Center in Muscle Shoals, Alabama, for their invaluable recommendations and
essential comments and to Frank Freestone of RREL for his ongoing support, suggestions, and technical
insight.
The following reviewers each contributed to the depth of this report through comments based on their
considerable expertise:
Patrick Augustin, EPA RREL
Dr. John E. Brugger, Ph.D., EPA RREL
JoAnn Camacho, EPA/Environmental Response Team (ERT)
Paul de Percin, EPA RREL
Linda Fiedler, EPA TIO
Johnathan Josephs, EPA Region II
William Lowe, Ph.D., P.E., WESTON
Shahid Mahmud, EPA OERR
Verrill M. Norwood, Jr., Pioneer Chlor-Alkali Co., Inc.
Michael Royer, EPA RREL
Kevin Rumery, DYNAMAC
Michelle Simon, EPA RREL
Don Stenitze, DYNAMAC
Ronald J. Turner, EPA RREL
Kenneth Wilkowski, Ph.D., EPA RREL
Walter Wujcik, Ph.D., P.E., WESTON
Andre Zownir, EPA/ERT
The authors express their appreciation to Patricia M. Sobota for technical editing, Angie GJresham and Amy
Doran for word processing, and Catherine McKeever and David Livingston for graphics.
XII
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SECTION 1
INTRODUCTION
PURPOSE
- This guide is designed to, assist remedial project managers (RPMs) in selecting appropriate treatment
technologies. It outlines the contaminants and remedial options for pesticide sites. Along with use of existing
United States Environmental Protection Agency (EPA or the Agency) guidance, it is intended to facilitate
remediation activities at sites where pesticides are the major contaminants. The information provided herein
should prove to be a useful tool for all remedial managers whether their efforts fall under federal, state, or
private authority within the Resource Conservation Recovery Act (RCRA), the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA), and/or equivalent state programs.
ORGANIZATION
This document identifies the types and sources of pesticide contamination (Section 2 - Pesticide
Chemicals and Sources of Contamination at Pesticide Sites) by characterizing contaminants and defining their
behavior in the environment (Section 2 - Pesticide Contaminant Behavior, Fate, and Transport) and evaluating
the available remedial technologies for use on pesticide sites (Section 3 - Remedial Options). The Remedial
Options section (Section 3) discusses the process specifics, media and pesticide waste groups applicability,
associated costs, status of implementation, performance, and data needs of the technologies for each of the
principal remediation options.
ESSENTIAL REFERENCES AND SOURCES OF INFORMATION
Readers of this document should be familiar with appropriate policy issues and applicable regulations
(RCRA, CERCLA, and state), risk assessment, and the determination of cleanup levels. Familiarity with the
references listed below is also necessary.
Policy
Corrective Action for Solid Waste
Management Units at Hazardous
Management Facilities; Proposed Rule [1].
Technical
Guidance for Conducting Remedial
Investigations and Feasibility Studies
under CERCLA [2].
Guidance for Conducting Treatability
Studies Under CERCLA - Interim Final [3].
This is the proposed Subpart S rule which defines
requirements for conducting remedial investigations and
selecting and implementing remedies at RCRA facilities.
This document provides an overall understanding of the
remedial investigation/feasibility study (RI/FS) process.
This booklet (currently under revision) describes the
necessary steps in conducting treatability studies to
determine technology effectiveness when remediating a
CERCLA site.
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Technical (Continued^
Innovative Treatment Technologies:
Annual Status Report, Fifth Edition [4]
Innovative Treatment Technologies: Semi-
Annual Status Report, Fourth Edition [5]
Superfund Innovative Technology
Evaluation Program: Technology Profiles,
Fourth Edition [6]
Superfund Innovative Technology
Evaluation Program: Technology Profiles,
Sixth Edition [7]
Guide for Conducting Treatability Studies
forCERCLA: Aerobic Biodegradation
Remedy Screening Guide [8]
This report documents the selection and use of innovative
treatments in the Superfund program and at non-Superfund
sites within the Department of Defense (DOD) and
Department of Energy (DOE).
This report provides information on innovative treatments
used in the Superfund Program and at non-Superfund,
DOD, and DOE sites.
This document profiles 129 demonstration, emerging, and
monitoring and measurement technologies being evaluated
by the Superfund Innovative Technology [Evaluation (SITE)
program.
In this document, 170 profiles are examined for
demonstration, emerging, and measurement technologies
being evaluated by the SITE program.
This document describes the necessary steps in conducting
treatability studies specifically for aerobic biodegradation
remedy screening.
Handbook on In Situ Treatment of
Hazardous Waste Contaminated Soils [9]
Summary of Treatment Technology
Effectiveness for Contaminated Soil [10]
Technology Screening Guide for
Treatment of CERCLA Soils and Sludges
[11]
RCRA Facility Investigation (RFI)
Guidance Volumes 1-4 [12]
This handbook provides state-of-the art information on in-
situ technologies for use on contaminated soils.
This report contains information on a number of treatment
options that apply to excavated soils, and explains the best
demonstrated and available technology (BOAT) contaminant
classifications.
This guide contains information on technologies which may
be suitable for managing soil and sludge containing
CERCLA waste.
These documents recommend procedures for conducting an
investigation and gathering and interpreting the data from
the investigation.
In addition, EPA has published engineering bulletins that discuss single technologies, including the
following:
Chemical Dehalogenation Treatment: APEG Treatment[13]
Chemical Oxidation Treatment [\ 4]
Granular Activated Carbon Treatment[15]
In Situ Soil Vapor Extraction Treatment [16]
In Situ Steam Extraction Treatment [17]
Mobile/Transportable Incineration Treatment [18]
Soil Washing Treatment119]
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• In Situ Soil Flushing [20]
• Solvent Extraction Treatment [21]
• Slurry Biodegradation [22]
• Thermal Desorption Treatment[23]
• Air Stripping of Aqueous Solutions [24]
Slurry'Walls [25]
• Rotating Biological Contactors [26]
• Pyrolysis Treatment [27]
• Supercritical Water Oxidation [28]
Much of this information is being collected on databases for quick retrieval, and many sources can
be found in the following documents:
• The Federal Data Base Finder [29] A comprehensive listing of federal databases and
data files.
Technical Support Services for
Superfund Site Remediation [30]
Bibliography of Federal Reports and
Publications Describing Alternative
and Innovative Technologies for
Corrective Action and Site
Remediation [31]
Bibliography of Articles from On-Line
Databases Describing Alternative
and Innovative Technologies for
Corrective Action and Site
Remediation [32]
Alternative Treatment Technology
Information Center (ATTIC) [33]
Vendor Information System for
Innovative Treatment Database
(VISITT) [34]
Identifies technical support services available to
field staff.
Contains references for documents and reports
from EPA,.U.S. Army, U.S. Army Corps of
Engineers (USAGE), U.S. Navy, U.S. Air Force,
DOE, and U.S. Department of the Interior (DOI).
Provides information for EPA remedial managers
and contractors who are evaluating cleanup
remedies.
A compendium of information from many available
databases. Data relevant to the use of treatment
technologies in Superfund actions are collected
and stored in ATTIC.
A database that contains information about
vendors of innovative technologies used for
treating groundwater (in situ), soils, sludges, and
sediments.
REMEDIATION STRATEGY AND SELECTION OF OPTIONS
The selection of remediation technology is based primarily on site specifications and established
cleanup goals. These goals are rooted in existing regulations arid determined after a site characterization is
completed. Site characterization includes toxicity, exposure, and risk assessments and identifies
contaminants, sources of contamination, and contaminated media matrices in order to quantify the magnitude
and extent of contamination and the threats posed by a site.
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Although explaining the site characterization and goal setting process is not the purpose of this
document, specific elements of these processes that relate to pesticide site cleanup are discussed.
Discussion of the pesticide site-specific contaminants and potential sources of pesticide contamination can
be found in Section 2. In this document, the discussion of the technologies is broken down into separate
subsections that address technologies by remediation option and media. The major matrices are broken down
into two groups: (1) soil, sediments, and sludges and (2) water. Air emissions (from destruction or
separation/concentration technologies) and their treatment are discussed herein as they relate to each of the
technologies. These media matrices are defined as the following.
• Soil, Sediments, and Sludges: This media group includes soils and particulate matter
intermixed with water or other aqueous components. Sludges may include metal hydroxides,
carbonaceous materials, silicates, and other industrial byproducts formed into a solids-liquid
mixture.
• Water: This media group includes groundwater, surface water, and contaminated washwater
or process water from soil, sediment, and sludge treatment processes.
• Air Emissions: This media group includes incidental air emissions relative to soils,
sediments, and sludge and water remediation activities.
The technologies available for remediation can be grouped by the methods used and their degree of
success in achieving a reduction of the toxicity, mobility, and/or volume of a contaminated media. The three
options, or basic approaches, include immobilization, destruction, and separation/concentration, as explained
below:
1. Immobilization technologies minimize or prevent contaminant migration. These
technologies use physical barriers to reduce the flow of contaminated groundwater or water
through contaminated media. Additionally, they use chemical reactions, physical interactions,
or both to retain or stabilize a contaminant and prevent its migration or interaction into the
environment. Immobilization technologies function only to limit the environmental mobility of
pesticides with no detoxification or volume reduction.
2. Destruction technologies use thermal, chemical, or biological processes to reduce or
eliminate toxicity and may result in significant volume and mobility reductions. Pretreatment
activities such as concentrating contaminants or contaminated materials are often required
to prepare media for processing with the final destruction technologies.
3. Separation/concentration technologies use physical or chemical processes to separate
contaminants from their media matrix for further treatment and possibly to reduce the volume
of contaminated material. These technologies do not alter the fundamental nature of the
contaminant toxicity or mobility, but rather collect contaminants into a concentrated form and
smaller volume or transform them into a different medium (such as by soil washing) that is
easier to handle for further treatment and disposal. Typically, separation/concentration
technologies prepare pesticides for further remediation by destruction or immobilization
technologies.
Remediation strategies for pesticide-contaminated sites may incorporate several distinct technologies
assembled into a treatment train to attain specific site cleanup goals. Combining technologies sequentially
or in parallel is often the best way to achieve site-specific objectives and acceptable residual contaminant
levels.
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The DeRewal Chemical Company site in Kingwood Township, New Jersey, is one site where
technologies are being implemented into a treatment train. This chemical manufacturing and storage facility
is contaminated with a fungicide, metals, volatile organics, and semivolatile organics. Organics were found
in the first 2 feet of topsoil, and inorganics were found to 4-feet deep. Several remediation strategies were
reviewed. The remedy selected in the Record of Decision (ROD) was a treatment train with a pretreatment
phase of contaminated soil excavation and a primary technology of thermal treatment of the organics-
contaminated soil [35]. The secondary treatment phase includes on-site solidification/stabilization of
inorganics-contaminated soil with residual soil from the thermal treatment that exceeded the New Jersey
Department of Environmental Protection and Energy (NJDEPE) action levels. Emissions from the thermal
treatment will be treated to remove organics and particulates to meet the provisions of the Clean Air Act.
To meet New Jersey Safe Drinking Water Act (SDWA) maximum contaminant levels (MCLs), the
treatment train selected in the ROD for groundwater remediation includes extraction of the shallow aquifer
followed by off-site treatment at an industrial wastewater treatment facility. Although this technology was not
the least expensive, it was one of the most effective solutions for long-term reduction of toxicity, mobility, and
volume of contaminated media.
Treatment trains that consist of volume reduction and containment processes as well as associated
material handling operations, separation/concentration technologies, and residual management make up a
complete remediation strategy to achieve contaminant levels within the established media cleanup goals. In
this document, the sections on treatment combinations and trains include tables to assist managers in
considering and selecting combinations of technologies. The treatment technologies at the center of the
treatment trains are discussed in detail. The following lists the information provided on each technology:
Applicability to pesticides
Status of implementation at pesticide sites
Treatment performance relative to pesticides or analogous compounds
Process specifics
Associated costs
Data needs of site-specific characteristics that could affect the technology's effectiveness
The technologies available under each of the remediation options are in different stages of application
and development. These stages are defined as the following:
• Proven (or established) technologies are those that have been used on a commercial
scale and established for use in full-scale remediations [e.g., incineration, capping,
solidification/stabilization (S/S)].
• Innovative treatment technologies are alternative treatment technologies (i.e., those
"alternative" to land disposal) for which use at Superf und-type sites is inhibited by lack of data
on cost and performance. According to EPA's current definition, these technologies include
the following [36]:
Chemical treatment
Dechlorination
Ex-situ bioremediation
In-situ bioremediation
In-situ flushing
In-situ vitrification
Microfiltration/membranes
Soil vapor extraction (SVE)
-------
Soil washing
Solvent extraction
Thermal desorption
Other technologies
Emerging technologies are those still being designed, modified, and tested in the laboratory
or on a pilot scale. They are not available for full-scale implementation (e.g., plasma-arc ultra
high temperature process, hydrodehalogenation, etc.).
It is important to consider how the selection of innovative vs. established technologies may affect the
completeness of the remediation. Innovative technologies may allow greater contamination and volume
reductions. They may cost more or take longer to implement because of the need for preliminary testing to
determine their appropriateness for full-scale use at a particular site. Since costs are rising for land disposal
and long-term operations and maintenance (O&M) for technologies such as capping, innovative technologies
that offer a more permanent solution may be worthwhile depending on the site and remediation goals.
Considerations for Cost Estimation [37]
For each cleanup strategy considered relevant to site-specific characteristics and goals, estimates
for capital and O&M costs should be performed. Capital costs can be subdivided further into direct capital
costs, which are defined as the following:
* Direct capital costs:
Remedial action construction
Component equipment
Land and site development
Building and services costs
Relocation of affected population
Disposal of waste material
• Indirect capital costs:
Engineering expenses
Contingency costs
Project management
• Operation and maintenance costs are those incurred after construction, but during the
remediation phase, to ensure continued efficiency of the treatment process. The major
components of O&M costs include:
Operating labor
Maintenance materials and labor
Auxiliary materials and energy
Residuals disposal
Purchased services
Administrative expenses
Insurance, taxes, and licenses
Maintenance reserve and contingency costs
-------
Many of the capital costs are at least partially independent of the size of the site to be remediated.
Operation and maintenance costs, however, may vary greatly depending on the type and amount of waste
treated. While total costs vary as a function of site size, the treatment cost per ton often decreases
dramatically as the site size increases. For example, Figure 1-1 [38] illustrates the effect of site size on the
cost of icineration.
94P-2OO2 4/7/a
1, OOO-
very Small Smai:. Medium
^5,000 5,000-15,OO015,000-30,000
Site Size (Tons Treated)
FIGURE 1-1 Effect of Site Size on Incinerator Cost [38]
REFERENCES FOR SECTION 1
1. "Corrective Action for Solid Waste Management Units at Hazardous Waste Management Facilities,
Proposed Rule," 55 Federal Register (27 July 1990) p. 30798.
2. USEPA. 1989. Guidance for Conducting Remedial Investigations and Feasibility Studies Under
CERCLA. EPA-540-2-89-004.
3. USEPA. 1989. Guidance for Conducting Treatability Studies Under CERCLA - Interim Final. EPA-
540-2-89-058.
4. USEPA. 1993. Innovative Treatment Technologies: Annual Status Report. Fifth Edition. EPA
542-R-93-003. Office of Solid Waste and Emergency Response, Washington D.C.
5. USEPA. 1992. Innovative Treatment Technologies: Semi-Annual Status Report. Fourth Edition.
EPA 542-R-92-011. Office of Solid Waste and Emergency Response, Washington D.C.
6. USEPA. 1991. The Superfund Innovative Technology Evaluation Program: Technology Profiles.
Fourth Edition. EPA 540-5-91-008. Office of Solid Waste and Emergency Response, Washington
D.C.
7. USEPA. 1993. Superfund Innovative Technology Evaluation Program. EPA-540-R-93-526. Office
of Solid Waste and Emergency Response, Washington D.C.
-------
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
USEPA. July 1991. Guide for Conducting Treatability Studies Under CERCLA- Aerobic
Biodegradation Remedy Screening Guide. EPA-540-2-91 -13a.
USEPA. January 1990. Handbook on In Situ Treatment of Hazardous Waste Contaminated Soils
EPA-540-2-90-002.
USEPA. June 1990. Summary of Treatment Technology Effectiveness for Contaminated Soil
OSWER-9355.4-06.
USEPA. 1988. Technology Screening Guide for Treatment of CERCLA Soils and Sludges EPA-
540-2-88-004.
USEPA. May 1989. RCRA Facility Investigation (RFI) Guidance (Volumes 1-4). EPA-530-SW-89-
03 i.
USEPA. 1990. Engineering Bulletin: Chemical Dehalogenation Treatment: APEG Treatment. EPA-
540-2-90-015. EPA Office of Emergency and Remedial Response, Washington, DC.
USEPA. 1991. Engineering Bulletin: Chemical Oxidation Treatment, Draft. ORD, Cincinnati, OH
and Office of Emergency and Remedial Response, Washington, DC.
USEPA. 1991. Engineering Bulletin: Granular Activated Carbon Treatment. EPA-540-2-90-024
EPA Office of Emergency and Remedial Response, Washington, DC.
USEPA. 1990. Engineering Bulletin: In Situ Soil Vapor Extraction Treatment. EPA-540-2-90-006.
EPA Office of Emergency and Remedial Response, Washington, DC, and Office of Research and
Development, Cincinnati, OH.
USEPA. 1991. Engineering Bulletin: In Situ Steam Extraction Treatment. EPA-540-2-90-005 EPA
Office of Emergency and Remedial Response, Washington, DC.
USEPA. 1990. Engineering Bulletin: Mobile/Transportable Incineration Treatment. EPA-540-2-90-
014. EPA Office of Emergency and Remedial Response, Washington, DC.
USEPA. 1990. Engineering Bulletin: Soil Washing Treatment. EPA-540-2-90-017. EPA Office of
Emergency and Remedial Response, Washington, DC, and Office of Research and Development
Cincinnati, OH.
USEPA. 1991. Engineering Bulletin: In Situ Soil Flushing. EPA-540-2-91-021. EPA Office of
Emergency and Remedial Response, Washington, DC, and Office of Research and Development
Cincinnati, OH.
USEPA. 1990. Engineering Bulletin: Solvent Extraction Treatment. EPA-540-2-90-013. EPA Office
of Emergency and Remedial Response, Washington, DC, and Office of Research and Development
Cincinnati, OH.
USEPA. 1990. Engineering Bulletin: Slurry Biodegradation. EPA-540-2-90-016. EPA Office of
Emergency and Remedial Response, Washington, DC.
USEPA. 1990. Engineering Bulletin: Thermal Desorption Treatment. EPA-540-2-90-008. EPA
Office of Emergency and Remedial Response, Washington, DC.
-------
24. USEPA. 1991. Engineering Bulletin: Air Stripping of Aqueous Solutions. EPA-540-2-91-022.
Office of Emergency and Remedial Response, Washington D.C., and Office of Research and
Development, Cincinnati, OH.
25. USEPA. 1992. Engineering Bulletin: Slurry Walls. EPA-540-S-92-008. Office of Emergency and
Remedial Response, Washington D.C., and Office of Research and Development, Cincinnati, OH.
26. USEPA. 1992. Engineering Bulletin: Rotating Biological Contactors. EPA-540-S-92-010. Office
of Emergency and Remedial Response, Washington D.C., and Office of Research and Development,
Cincinnati, OH.
27. USEPA. 1992. Engineering Bulletin: Pyrolysis Treatment. EPA-540-S-92-10. Office of Emergency
and Remedial Response, Washington D.C., and Office of Research and Development, Cincinnati,
OH.
28. USEPA. 1992. Engineering Bulletin: Supercritical Water Oxidation. EPA-540-S-92-010. Office
of Emergency and Remedial Response, Washington D.C., and Office of Research and Development,
Cincinnati, OH.
29. Information USA. 1990. The Federal Data Base Finder - A Directory of Free and Fee-Based Data
Bases and Files Available from the Federal Government, Third Edition. Kensington, MD.
30. USEPA. 1990. Technical Support Services for Supeiiund Site Remediation, Second Edition. EPA-
540-8-90-011. EPA Office of Solid Waste and Emergency Response, Washington, DC.
31. USEPA. 1991. Bibliography of Federal Reports and Publications Describing Alternative and
Innovative Treatment Technologies for Corrective Action and Site Remediation. EPA-540-8-91 -007.
Center for Environmental Research Information, Cincinnati, OH.
32. USEPA. 1991. Bibliography of Articles from Commercial Online Databases Describing Alternative
and Innovative Technologies for Correction Action and Site Remediation. Information Management
Services Division, Washington, DC.
33. ATTIC (Alternative Treatment Technology Information Center) Online System, computerized
database and electronic bulletin board on treatment of contaminated materials. Information: J.
Perdek, EPA, (908) 321-4380; Modem Access: (301) 670-3808.
34. VISITT (Vendor Information System for Innovative Treatment), computerized database of innovative
treatment technologies for hazardous waste remediation. Information: L. Fiedler, EPA, (800)
245-4505, (703) 283-8448.
35. USEPA. n.d. ROD (Record of Decision): EPA-ROD-RO2-89-087.
36. USEPA. April 1992. Innovative Treatment Technologies: Semi-Annual Report. EPA-540-2-91-001.
37. USEPA. October 1987. Remedial Action Costing Procedures Manual. EPA Contract 68-03-3113,
EPA, Office of Emergency and Remedial Response, Washington, DC.
38. Roy F. Weston, IncVREAC and Foster Wheeler Enviresponse, Inc. 1993. EPA Contracts 68-03-3482
and 68-C9-0033. "Contaminants and Remedial Options at Solvent-Contaminated Sites." Draft
Document. Roy F. Weston, Inc. and Foster Wheeler. Edison, NJ.
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SECTION 2
CONTAMINANTS AT PESTICIDE SITES
INTRODUCTION
Pesticides are defined in the U.S. Federal Environmental Pesticide Control Act as ".. any substance
or mixture of substances intended for preventing, destroying, repelling, or mitigating any insect, rodent
nematode, fungus, weed or any other form of terrestrial or aquatic plant or animal life or virus, bacteria or other
microorganism which the Administrator declares to be a pest" with the exception of human diseases [11
These include any substance or mixture of substances intended for use as a plant regulator, defoliant or
desiccant. Pesticides do not include fertilizers or veterinary medicines.
HISTORICAL USE OF PESTICIDES
The quantity and diversity of pesticides in production and use has coincided with the rapid growth of
the synthetic organic chemical industry which began during the 1930s and 1940s. Prior to World War II, the
most commonly used pesticides were inorganic chemicals and naturally occurring organics, primarily plant
extracts such as nicotine, pyrethrum, and derris [2]. The most common inorganic pesticides included the
arsenical compounds such as lead arsenate [3] and sulfur and mercury compounds [2]. The insecticidal
properties of dichlorodiphenyltrichlorethane (DDT) were discovered in 1939 [2], and the use of synthetic
organic insecticides in the United States grew from approximately 140 tons in 1940 to 8,000 tons in 1944.
By 1965, approximately 300 organic pesticides in over 10,000 formulations were on the market [4]-
In 1980, more than 1,850 pesticide chemicals were used as active ingredients in some 33,600 pesticide
products registered by EPA with approximately 4,300 world-wide manufacturers and distributors [3]. By 1991,
the list of registered pesticide products had grown to approximately 23,400, with 900 registered active
ingredients (Al). Total U.S. production of pesticides in 1988 was estimated at 640,000 tons [5]. The
distribution of these products among common pesticide types is illustrated in Table 2-1. However, the number
of active ingredients in those pesticide products considered principal site pollutants is significantly smaller than
those described below.
TABLE 2-1. DISTRIBUTION AMONG PESTICIDE PRODUCTS T31
Type
Percent of Total
Insecticides
Diversified Household/Industrial Pesticides
Herbicides
Fungicides
Rodenticldes
49.3%
23.1%
15.4%
9.1%
3.1%
REGULATION OF PESTICIDES
The production, use, and disposal of pesticides in the United States is regulated under the Federal
Insecticide, Fungicide, and Rodenticide Act (FIFRA) [1], originally enacted in 1947 and subsequently amended
in 1972, 1975, 1978, 1988, and 1990. The current regulatory program is based primarily upon the 1972
amendment, known as the Federal Environmental Pesticide Control Act.
10
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Among other provisions, FIFRA requires the registration of all pesticide products with the EPA prior
to distribution, sale, or use in the United States. Pesticides are classified for either "general" or "restricted"
use. General use pesticides are those which the EPA determines generally will not cause unreasonable
adverse effects on the environment. Restricted use pesticides are those determined to cause, without
additional regulatory restrictions, unreasonable adverse environmental effects, including injury to the
applicator. Provisions exist in the law for cancelling the registration of a pesticide under certain
circumstances.
Through administration of the pesticide registration program and site investigation, EPA has
developed extensive data on specific pesticide products and wastes [6,7,8]. These data may be useful to
remedial managers for evaluating sites where specific pesticides and pesticide products were produced,
formulated, used, or disposed.
Additionally, FIFRA provides for the certification of private and certified applicators of pesticides,
registration, and inspection of production facilities, establishment of disposal requirements, and enforcement
provisions. FIFRA does not include cleanup requirements or the authority to require cleanup of released
pesticides. This authority lies with Superfund, RCRA, and state or local regulations.
PESTICIDE CHEMICALS
The term pesticide is applied to literally thousands of different, specific chemical-end products.
Pesticides include insecticides, fungicides, herbicides, acaricides, nematocides, and rodenticides. There are
several commonly used classification criteria which can be used to group pesticides for purposes of
discussion. Conventional methods of classifying pesticides base categorization on the applicability of a
substance or product to the type of pest control desired. (For example, DDT is used typically as an
insecticide.) The RCRA hazardous waste classification system is based on waste characterization and
sources. Neither of these classification formats is suitable for use in this document since they have no bearing
- on applicable pesticide treatment technologies. Nor is it within the scope of this document to present a
complete listing of all pesticides. Such information is available in the referenced literature [11-18], and readers
should refer to these and other publications for more detailed information whenever possible.
For the purpose of evaluating the treatment technology effectiveness for contaminated soil, EPA has
categorized chemical contaminants commonly found at Superfund sites into 13 waste groups [9]. This
Superfund method was considered for similar application to pesticides named in this document. This grouping
system has been reduced based on the available treatment options and is categorized into the following four
waste groups:
• WG01 - Inorganic pesticides
• WG02 - Halogenated water insoluble organics
• WG03 - Halogenated sparingly water soluble organics and organo-linked compounds
• WG04 - Nonhalogenated organics and organo-linked compounds
The four waste groups will facilitate discussion and evaluation of various technologies to control
pesticide contamination (Section 3). Table 2-2 is a list of the four pesticide waste groups, examples of
commonly found pesticides, and their respective uses (as insecticide, herbicide, fungicide, acaricide,
nematocide, or rodenticide). These four groups are subdivided further to show their relationship with the EPA
Superfund treatability waste groups [9]. Additionally, these groups are broken down into "families" of chemical
classes according to their molecular structure or key functional groups in order to illustrate the nature of
various pesticides. A functional group is "a collection of atoms that occurs in many carbon compounds and
that behaves roughly the same way in all compounds [10]."
11
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This classification scheme is pertinent to the site remediation strategy because the chemical structure
of the pesticide compound itself (sometimes in combination with other components of the pesticide formulation
such as solvents and carriers) directly affects (1) toxicity and potential environmental hazards, (2) mobility and
transport through and between environmental media, and (3) applicability of various remedial treatment
technologies in terms of removal/destruction efficiencies, residual products and concentrations, pre- and post-
treatment requirements, and costs. These effects are derived from the influence of chemical structure/
functional groups on such properties as solubility, volatility, octanol/water partition coefficient, adsorption
characteristics, etc. Additionally, the response of a particular pesticide to any treatment selected is influenced
by its chemical structure.
To avoid misunderstanding or misuse of waste groups or the information listed in Table 2-2, readers
should be aware of the following factors which affect the nature of contamination at any given site.
• Since pesticide contamination is often a complex problem, for a site to be properly
characterized, extensive sampling and testing are required.
• Most pesticide wastes are complex mixtures of chemicals and not pure pesticides.
• Pesticide wastes or a contaminated site may contain pesticides from more than one waste
group.
• Contaminants listed in Table 2-2 are mainly chemicals marketed as pesticides. Some raw
materials (e.g., hexachlorocyclopentadiene and other solvents), by-product chemicals (e.g.,
dioxins and furans), and intermediate products of degradation [e.g., ODD,
dichlorodiphenyldichloroethylene (DDE), ethyleneiourea (ETU)] can be major contaminants
at pesticide waste sites, but may not be listed as pesticide wastes in Table 2-2.
• In particular, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other dioxins and furans are
often byproducts of high temperature processes employed during the manufacture of certain
pesticides (e.g., 2,4-D herbicide). Because of the extreme toxicity of these compounds at
very low concentrations and because of special regulatory requirements for certain
polychlorinated dioxin and furan wastes under RCRA, the presence of these compounds has
determined the direction of cleanup efforts at many pesticide waste sites even though they
are not pesticides.
• Pesticides listed within the halogenated water insoluble organics waste group (WG02) may
still be soluble at very trace concentrations and may leach from contaminated soils,
sediments, and sludges into the groundwater.
• Pesticides are often formulated with carriers or emulsifiers that greatly affect the solubility,
mobility, and extent of site contamination.
To use this guide effectively, the remedial manager should have (1) the identity of the pesticide(s) of
concern in a given remediation application, and (2) a basic knowledge and understanding of chemistry or
affiliation with a colleague who does (i.e., contractors, chemists, etc). If the identity of the pesticide is known,
its chemical structure can be determined by consulting one or more of the references listed in this document.
Then, the pesticide can be classified into one of the four pesticide chemical waste groups listed in Table 2-2,
which also contains possible treatment alternatives for each waste group. Alternatively, if a pesticide's EPA
Superfund classification is known (see reference [9]), it can be categorized within its waste group. The Merck
Indexed] and the Herbicide Handbook of the Weed Science Society of America [20] are helpful for obtaining
information about pesticide properties.
12
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NOTE: For proper placement, additional information is required for compounds classified in the EPA
Superfund groups W03, W05, W06, or W13 since theses groups may belong to more than one
pesticide chemical waste group.
SOURCES OF CONTAMINATION AT PESTICIDE SITES
In addition to identifying the contaminants of concern at a site, the remedial manager must identify
the potential primary and secondary sources of pesticide contamination. There are several possible sources
of pesticide contamination at manufacturing, storage, or user sites. The most serious examples of pesticide
contamination are typically the result of poor production and waste management practices at pesticide
manufacturing, formulation, and application facilities. Improper storage, handling, and disposal also have
resulted in pesticide contamination at these sites and at landfills. Table 2-3 lists possible pesticide
contamination sources for several facility types.
The mode of contamination may provide insight into factors that may affect pesticide distribution and
migration. For example, the low water solubility of DDT normally suggests relatively low potential for
groundwater-borne migration. However, if a site had been used for DDT manufacture, chemicals used in the
manufacturing process (e.g., chlorinated benzenes) may have been introduced as contaminants. These
chemicals may increase the mobility of DDT substantially through cosolvent effects, resulting in significant
groundwater contamination. Likewise, the solvents and carriers used at pesticide preparation or application
sites may affect the mobility of the pesticide constituents. Because of such possibilities, the importance of
adequate historical investigation at pesticide sites is necessary to effectively characterize the potential areas
of contamination and to assist in the evaluation of appropriate control technologies.
TABLE 2-3. PESTICIDE CONTAMINATION SOURCES
Facility Type
Manufacturing/Formulation
Storage
Application
Disposal
Possible Sources of Contamination
Poor production and waste management practices
Wastewater and sludge impoundments
Spillage/Leakage in processing equipment and sewer lines
Leaching drums or other containers
Heavy application
Aerial Application
Improper procedures at mixing areas
Landfills
Improper/Unauthorized disposal
CONTAMINANT BEHAVIOR, FATE, AND TRANSPORT
Predicting Contaminant Behavior
Predicting the fate of the contaminant requires the acquisition and interpretation of complex site
characterization data for each chemical compound of concern. Selecting a remedial strategy includes
considering the individual contaminant's toxicity, persistence, migration pathways, and rate of transport from
a site. Based on these characteristics, the remedial manager can prioritize needs to control toxicity and
15
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mobility, to characterize adequately the potential areas of site contamination, and to assist in the evaluation
of appropriate control technology. The following are mechanisms of pesticides fate and transport that affect
the extent of site contamination:
• Adsorption on soils
• Biodegradation
• Volatilization
• Downward migration
• Lateral migration
• Photolysis
Adsorption of pesticides on the soil surface is a dominant factor that affects the site contamination's
extent. Because smaller soil particles have greater total surface areas, soils consisting mainly of silt and clay
tend to adsorb higher concentrations of contaminants than coarser soils such as sand. Most pesticides are
adsorbed easily on soils because of their relatively high molecular weight. Other factors that affect the degree
of adsorption include: soil moisture, organic content, pH, cation exchange capacity of soils, and the
physical/chemical characteristics of various pesticide compounds.
Biodegradation of pesticides to relatively harmless end or intermediate products by soil bacteria
under natural (unenhanced) conditions is usually a relatively slow process because of the inhibitory effect of
pesticides (particularly at high concentrations), lack of proper nutrients and oxygen, unfavorable pH or
moisture conditions, and lack of acclimated culture. Highly halogenated pesticides are typically more difficult
to degrade biologically and often persist in the environment for a long time. Nevertheless, bioremediation may
be applicable to many types of pesticides, particularly if it is enhanced (such as by adding nutrients and
oxygen) to increase the rate of degradation.
Volatilization is a process by which a chemical compound is released to the atmosphere in the form
of a vapor or gas. Few pesticides are known to be volatile. Most of these belong to the lower molecular
weight halogenated aliphatic compounds (e.g., ethylene dibromide, dibromochloropropane, and methyl
bromide) within waste group WG03. Other chemical compounds that are not pesticides but are used as
solvents in the manufacturing process or as carriers in the formulation of pesticides may be volatile and exist
at a contaminated site. The rate of volatilization for an individual compound is controlled mainly by the Henry's
law constant, which is the ratio of the concentration of contaminant in the vapor phase to the concentration
of contaminant in the liquid equilibrium phase [21,22]. Other factors that affect the rates of volatilization
include diffusion within the soil media (which, in turn, is affected by the soil particle sizes), soil moisture and
temperature, soil organic matter content, and wind speed.
Downward migration (leaching) of pesticides is caused mainly by percolation of stormwater through
the contaminated soil media, which causes the dissolved portion of organic or inorganic compounds to enter
the groundwater aquifer and be carried away. A major factor controlling the downward migration of pesticides
is the solubility of chemical compounds in water. Additionally, sometimes nonaqueous phase liquid (NAPL)
of organic compounds may migrate downward without first being solubilized into water.
Lateral migration occurs when contaminant plumes containing pesticides disperse and move
horizontally through the groundwater aquifer. Plume migration is affected mainly by the hydraulic conductivity
of the soil media in the groundwater saturated zone and the hydraulic gradient of the water table. Lateral
migration of contaminated plumes often can be controlled by the use of slurry walls to create barriers of low
hydraulic conductivity and/or controlled pumping at strategic well points to change the hydraulic gradients of
the water table within or near a site.
16
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Photolysis is the process by which chemical bonds in pesticides are broken under the influence of
light. Light sources may be of natural or artificial origin and include the ultraviolet (UV) and visible range. In
photolysis, light energy is absorbed by a pesticide molecule which disrupts the pesticide's chemical structure
(i.e., a chemical break in the chemical bond occurs). This results in the formation of new chemical species
[23].
Chemical Formulation and Its Influence on Pesticide Toxicity. Migration, and Transformation
Selecting a remedial action for site cleanup should be based upon a clear understanding of the
physical, chemical, and biological processes influencing the toxicity, degradation, and movement of a
pesticide.
Chemical Structure-
The type, number, and positioning of atoms that form a pesticide's molecular structure govern its
biological, chemical, and physical attributes. Seemingly minor structural modifications may dramatically alter
behavior. Substituting a hydroxyl group for a chlorine atom on hexachlorobenzene to form pentachlorophenol
(PCP), for example, increases water solubility from 0.0062 parts per million (ppm) to 1950 ppm at 25 °C [24].
Removing a chlorine atom from linuron to form monolinuron raises water solubility from 75 ppm at 25 °C [24]
to 580 ppm at 20 °C [17]. Repositioning atoms from a beta to gamma isomer configuration for BHC elevates
water solubility from 0.24 ppm to 31.4 ppm at 25 °C [24].
Behavioral differences are often greatest between compounds with dissimilar functional groups. In
the previous example, differences in water solubility were greatest between organochlorine and
aryloxyalkanoic acid functional groups (i.e., hexachlorobenzene and PCP, respectively). Molecular alterations
not directly involving a functional group often invoke less dramatic changes. For example, dechlorination of
linuron to monolinuron probably elevates water solubility to a lesser degree because urea functional groups
remain unchanged during the dechlorination process. Property variations ascribed to isomers are normally
less than differences stemming from dissimilar functional grouping (e.g., water solubility of the
hexachlorohexane isomers alpha and gamma BHC).
While there may be many exceptions to the rule, the functional group of a compound normally has
the greatest influence on a pesticide's properties. Once general properties associated with a particular
functional group are known, the remedial design engineer can use this information to screen out impractical
remedial options. For example, if past experience with a site has proven aryloxyalkanoic extraction by "pump
and treat" systems as unsuccessful, attempts at removal of cyclodienes by the same method under analogous
conditions probably will be unsuccessful as well.
Pesticide Concentration-
When applied at manufacturer-recommended concentrations, most pesticides slowly migrate through
the vadose zone and reach the water table in very dilute form. Adsorptive forces, bolstered by the presence
of soil organic matter (OM) may retain a high percentage of lipophilic compounds in the rooting zone. In some
cases, when no free nonaqueous phase liquid (NAPL) is present, concentrations are well below the solubility
limit, and degradative mechanisms may commence after a relatively short period of acclimation. Only a small
fraction of the original (undegraded) compound may ever reach the water table.
Mobility and degradation patterns may be radically altered when concentrated pesticide from a point
or line source is involved. Aboveground spills and subterranean leakage from disposal sites and piping may
jntroduce concentrated aqueous phase and NAPL pesticides to the subsurface. Pesticides manufactured in
granular, pelletized, or encapsulated form which are spilled inadvertently may solubilize and infiltrate into soil
under the influence of percolating water (Table 2-2). Pesticide percolation may move rapidly to the water table
when concentrations are excessive.
17
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While the literature is replete with information on the mobility and degradability of many pesticides at
low, nonpoint source concentrations, little available information addresses loading rates spanning levels found
at hazardous waste sites. A study conducted at the University of Florida, Gainesville [23] found that
subsurface mobility for high concentrations of atrazine (WG02), 2,4-D (WG03), methyl parathion (WG03)
terbacil (WG03), and trifluralin (WG03) was related inversely to pesticide concentration in the soil solution
phase. For high concentrations of 2,4-D in groundwater, mobility could be underestimated by two orders of
magnitude.
The rate of microbial transformation and mineralization of a pesticide is influenced also by the
compound's concentration and toxicity. Response of microbial activity to high pesticide soil solution
concentrations may range from a simple extension of the acclimation (lag) period to sterilization. The
Gainesville report indicated that the time required for (microbial) degradation to begin was longer for high
concentrations (>50 ppm] than for low concentrations and that the lag period was directly related to pesticide
concentration [25].
Using a low concentration pesticide property data to predict mobility, degradation rates, etc., can lead
to erroneous predictions and selection of inappropriate remedial measures. A more conservative approach
considers the significance of the concentration/mobility correlation before a method of site cleanup was
selected.
Formulations and Carriers-
Generally, pesticides are manufactured at technical grade [90+ percent active ingredient (Al)] except
when they can be sprayed neat (undiluted). Most popular pesticides are formulated as dusts, emulsifiable
concentrates (EC), granules, solutions, and wettable powders (WPs) [24]. Dusts are a popular way of
applying insecticides and fungicides, but they are not used in herbicide applications. The form produced by
the manufacturer depends upon the properties of the Al, e.g., chemical stability in the presence of heat,
moisture, and oxygen; density; melting point; dissolution rate; miscibility; and oil/water solubility [26].
An emulsion is a stable dispersion of one liquid in a second immiscible liquid. Many pesticides are
dissolved in suitable oils or organic solvents with the addition of emulsifiers and are packaged as ECs which
typically contain from 0.12 to 0.48 kilograms (kg) of active ingredient per liter (kg Al/liter) [26]. Trifluralin and
ester formulations of 2,4-D, 2,4,5-T (silvex), and 2-methyl-4-chlorophenoxyacetic acid (MCPA) (WG03) and
other oil-soluble pesticides are formulated as emulsions and acquire a milky-white appearance when mixed
with water. Both volatile and nonvolatile solvents are used in the formulation of ECs. Volatiles, such as
toluene and xylene, evaporate after spraying and leave pesticide residue on the sprayed area. In contrast,
nonvolatiles, such as alkylated naphthalenes or petroleum oil, leave a mixture of pesticide and oil on the
treated surface after the water carrier has evaporated.
Wettable powders are formed by applying pesticides to finely ground clay particles treated with a
wetting agent. The mixture is suspended in oil with emulsifiers to produce a flowable product. Pesticide
granules are made by diluting pesticide with both inert and functional ingredients permitting a gradual release
of Al over time.
In the past, petroleum fuel fractions were used singly or as a pesticide "carrier." Additionally,
petroleum fuel fractions were used to treat mosquito larvae and livestock parasites; as adjuvants they
enhanced herbicide and fungicide activity. In either application, petroleum hydrocarbons were mixed with an
emulsifier to permit dilution with water.
The properties of a formulation not only affect the target organism, but also suggest how it will behave
in contaminated media. Consideration of the chemical formulation and resulting behavior is necessary to
understand the mobility and toxicity characteristics of the pesticide and to evaluate applicable control options.
18
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Surfactants--
Surfactants (surface active agents) are long-chain hydrocarbons with ionizable functional groups
(anionic or cationic) or nonionized molecules consisting of a hydrocarbon portion connected to multiple glycol
ether linkages (nonionic). Typically, they are used as detergents, dispersants, emulsifiers, spreading agents,
wetting agents, etc. One or more surfactants are used with nearly all herbicides because the hydrophobia
nature of many pesticides makes them nearly immiscible in water. They are able to disperse or solubilize an
otherwise insoluble, nonpolar pesticide into water by reducing the surface tension of an aqueous solution.
Mixing and adhesion problems are surmounted by the addition of surfactants to pesticide/carrier
admixtures. Surfactants dramatically alter many of the physical, chemical, and a pesticide's biological
properties. Changes in a pesticide's viscosity, water solubility, and toxicity may be influenced by the type and
concentration of the surfactant. A pesticide's toxicity and persistence may be altered by addition of either an
inappropriate surfactant or a suitable surfactant at the wrong concentration. Because activity and persistence
reactions highly depend upon surfactant/pesticide concentration interactions, selecting the most appropriate
combination is often made on a case-by-case basis or upon manufacturer's recommendations.
Surfactants can extend a pesticide's persistence in environmental media. Two months after
application, Lichtenstein [27] found concentrations in soil of parathion and diazinon mixed with anionic
surfactants to be 13 and 5 times higher, respectively, than in soils receiving insecticides alone.
Contaminant Behavior Related to the Four Waste Groups
There is a wide range of physical and chemical properties exhibited by pesticides within any given
waste group. Because physical and chemical properties greatly influence the treatment technologies that
prove effective for a particular pesticide, this information should be used only as a guide. Additional
information specific to the pesticide(s) in a particular remediation application should be obtained in order to
effectively identify and optimize the treatment options available.
Inorganics (WG01)--
Most of the inorganic pesticides, such as lead arsenate, zinc phosphide, and other sulfur-containing
compounds, were developed prior to World War II for control of agricultural pests. These pesticides have
been mostly replaced by the more effective organic compounds prepared by modern synthetic methods. The
aforementioned inorganic pesticides tend to persist in the environment for a long time. However, depending
on pH levels, the inorganic pesticides eventually may become dissolved in water and migrate downward or
laterally and can cause contamination in waterways or grouindwater.
Halogenated Water Insoluble Organics (WG02)--
Although the halogenated water insoluble organics (WG02) group of pesticides is classified as "water
insoluble," (Table 2-2) most of the compounds, depending on polarity, can be dissolved in water at
concentrations that, while very low, still may be toxic to aquatic life.
Most halogenated aromatic and alicyclic hydrocarbon pesticides tend to become tightly adsorbed on
soils, particularly when they have high clay, silt, and organic carbon contents. Usually, it is difficult to remove
the contaminated material from the groundwater below contaminated soils by the "pump and treat" methods.
Once the soils are contaminated by this waste group of pesticides, excavation of contaminated soils followed
by treatment (such as acid digestion and soil washing) often is required to achieve cleanup goals. Depending
on the type of compounds and their biodegradability, an in-situ bioremediation method may be employed;
however, this approach can involve long-term treatment and subsequent monitoring to cleanup a site.
19
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Halogenated Sparingly Water Soluble Organics and Organo-Linked Compounds (WG03)-
The halogenated sparingly water soluble organics and organo-linked compounds are most likely to
cause groundwater pollution problems because they tend to dissolve in water. (See Table 2-2 for examples.)
The halogenated aliphatics within this waste group are mostly volatile and often can be removed from
contaminated soils or groundwater by in-situ volatilization, a relatively inexpensive method. Other compounds
may require additional treatment methods, particularly if some of the complex compounds are tightly bound
by a soil matrix containing a large fraction of fine particles and organic matter.
Nonhalogenated Organics and Organo-Linked Compounds (WG04)--
Because of the chemical diversity of the nonhalogenate'd organics and organo-linked compounds,
some compounds may be partially water soluble while others may be tightly bound on contaminated soils.
A combination of various treatment methods for a contaminated site, such as groundwater "pump and treat,"
in-situ bioremediation, and/or excavation of contaminated soils followed by soil washing and other destruction
methods may be necessary for site cleanup. Extensive site investigation and laboratory treatability or pilot
tests usually are required for proper determination of the best action for each specific case.
REFERENCES FOR SECTION 2
1. Federal Insecticide, Fungicide, and Rodenticide Act, Public Law 92-516.
2. Newman, J.F. 1978. "Pesticides." Pesticide Microbiology. I.R. Hilland and S.J.L Wright, Editors.
Academic Press.
3. Sheets, TJ. 1980. "Agricultural Pollutants." Introduction to Environmental Toxicity, Frank E. Guthrie
and Jerome J. Perry, Editors. Elsevier North Holland Inc.
4. Mitchell, L.E. 1966. "Pesticides: Properties and Prognosis," Organic Pesticides in the Environment,
Advances in Chemistry Series 60. American Chemical Society.
5. Aspeling, A..L, A.H. Grube, and R. Torla. 1992. "Pesticides Industry Sales and Usage: 1990 and
1991 Market Estimates." USEPA, Economic Analysis Branch, Biological and Economic Analysis
Div., Office of Pesticide Programs.
6. USEPA. 1988. Pesticides in Ground Water Data Base: 1988 Interim Report. Environmental
Fate & Ground Water Branch, Environmental Fate & Effects Division, Office of Pesticide
Programs, EPA 540-09-89-036.
7. USEPA. 1991. FATE: The Environmental Fate Constants Information System Database.
Environmental Research Laboratory, Office of Research and Development, Athens, GA.
8. USEPA. 1990. National Survey of Pesticides in Drinking Water Wells. EPA 570-9-90-015.
9. Camp, Dresser, and McKee (COM). August 1989. Superfund Treatability Clearinghouse
Abstract. EPA-540-2-89-001.
10. Morrison, J.D. 1979. Organic Chemistry. Wadsworth Publishing Co., Belmont, CA.
11. Buchel, K.H., Editor. 1983. Chemistry of Pesticides. John Wiley & Sons, New York.
12. Eto, M. 1974. Organophosphorus Pesticides: Organic and Biological Chemistry. CRC Press,
Boca Raton, FL.
20
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13. Fukuto, T.R. 1987. "Organophosphorus and Carbamate Esters: The Anticholinesterase
Insecticides." Fate of Pesticides in the Environment, J.W. Biggar and J.N. Seiber, Editors.
Ag. Exper. Sta., Univ. Cal, Oakland, CA., Pub 3320, pp. 3-18.
14. Lee, H.B., A.S.Y. Chau, and F. Kawahara. 1982. "Oirganochlorine Pesticides." Analysis of
Pesticides in Water, Chau, A.S.Y. and B.K. Afghan, Editors. CRC Press, Boca Raton, Fl., Vol 2,
pp. 60.
15. Loos, M.A. 1975. "Phenoxyalkanoic Acids." Chemistry, Degradation, and Mode of Action,
Second edition, P.C. Kearney and D.D. Kaufman, Editors. Marcel Dekker, New York., Vol 1., pp
1-128.
16. Farm Chemicals Handbook. 1991. C. Sine, Editor. Meister Publishing Co., Willoughby, OH.
17. Royal Society of Chemistry. 1987. The Agrochemicals Handbook. Second Edition. Nottingham,
England.
18. Smith, A.E. 1988. "Transformations in Soil." Environmental Chemistry of Herbicides, R. Graver,
Editor. CRC Press., Boca Raton, Florida, Vol.1, pp. 171-200.
19. The Merck Index. 1989. Eleventh Edition. Susan Budavari, Editor. Merck & Co., Inc., Rahway,
NJ.
20. Herbicide Handbook of the Weed Science Society of America. 1989. Sixth Edition. Weed
Science Society of America, Champaign, IL.
21. Treybal, R.E. 1980. Mass Transfer Operations. Third Edition. McGrawHill.
22. Perry, H. and D. Green. 1990. Perry's Chemical Engineer's Handbook. Sixth Edition. McGraw
Hill. ,
23. CHEMFATE and BIODEG online databases. 1991. Syracuse Research Corporation, Syracuse,
NY.
24. Kiang, Yen-Hsiung and Amire Metry. 1982. Hazardous Waste Processing Technology. Ann
Arbor Science Publishing, Inc., Ann Arbor, Ml.
25. USEPA. 1980. Adsorption, Movement, and Biological Degradation of Large Concentrations of
Selected Pesticides in Soil, Phase I Report. EPA-600-2-80-124.
26. Himel, C.M., H. Loats, and G.W. Bailey. 1990. "Pesticide Sources to the Soil and Principles of
Spray Physics." Pesticides in the Soil Environment: Processes, Impacts, and Modeling, H.H.
Cheng, Editor. Soil Science Society of America, Madison, Wl.
27. Lichtenstein, E.P. 1966. "Increase of Persistence and Toxicity of Parathion and Diazinon in Soils
with Detergents." Journal of Economic Entomology, 59:985-993.
21
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SECTION 3
REMEDIAL OPTIONS
INTRODUCTION
This section discusses all available remediation technologies (other than off-site land disposal) and
focuses on the key factors that influence their appropriateness for use at pesticide-contaminated sites.
Information on each technology's applicability, implementation status, treatment performance data, process
specifics, cost, and data needs is provided to assist the remedial manager in determining whether the
implementation of a particular technology, remediation strategy, or treatment train will be successful in meeting
site goals. Within the scope of this document, a treatment train is defined as a combination of at least two unit
operations required (1) to reduce the volume of material requiring further treatment or (2) to remediate multiple
contaminants within a medium. At least one of the unit operations within the treatment trairi consists of a
contaminant remediation process.
Each technology's subsection includes a treatment train table outlining the various unit processes that
can be built around the primary treatment technology. Note that a technology chosen as the principal
component of the treatment train [e.g., incineration as the primary treatment of soil with secondary
solidification/stabilization (S/S) of the residuals] could be the secondary component in another train (e.g.,
desorption as the primary treatment and incineration for secondary treatment of the extracted contaminants).
The remedial manager must consider each element in a system, from excavation or pumping to treatment of
residual streams, both for applicability and cost projection.
Data specific to treatment trains used at Superfund remedial action are presented in Table 3-1. While
not every remedial action occurred at a pesticide-contaminated site, each treatment train included uses one
or more innovative technologies. Pesticide sites with more stringent cleanup goals probably need a
technology that requires a higher energy input. Figures 3-1 a, b, and c illustrate available technologies under
each option for the remediation of soil, sediments, and sludges in terms of their relative energy use and
residual concentrations in the media after their application. Some pesticides may require more or less energy
than indicated to break down or remove them, and some may not be amenable to all of the technologies listed.
A combination of technologies may be required to meet cleanup levels without implementing more energy
consuming or expensive technologies.
The cost information presented includes the capital and O&M costs discussed in Section 1. It is
intended to be used as a guide only, giving an order-of-magnitude sense of what a particular technology might
cost. Specific cost information for the technologies is not readily available and is highly variable depending
on the vendors and specific site conditions. The treatment costs for well developed field-tested components
(such as incineration and capping systems) can be reasonably reliable, but estimates for innovative and
emerging technologies become increasingly unreliable. Because of the current lack of ultimate disposal sites
and rapidly escalating disposal costs, for each project, detailed cost estimates should be prepared based on
specific process sizing of all required facilities, specific O&M needs, and a properly defined approach for
handling the ultimate disposal of residuals.
The data needs for each technology contain information regarding parameters relative to the waste
and site's chemical and physical characteristics that may affect the technology's effectiveness. The
technology's applicability and performance may be altered by these factors, rendering it ineffective for
achieving site goals. The data needs are meant to serve as a guide to general information needed to assess
the applicability of a remediation technology during the site characterization phase.
22
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TABLE 3-1. TREATMENT TRAINS WITH INNOVATIVE TREATMENT TECHNOLOGIES IN
SUPERFUND REMEDIAL ACTIONS [1]
Treatment Train
Soil washing followed by:
Bioremediation
Incineration
S/S
Thermal desorption/
Incineration
S/S
Dehalogenation
Soil vapor extraction/
In-situ bioremediation
In-situ soil flushing
S/S
Soil washing
Dechlorination/Soil Washing
Solvent extraction/
S/S
Soil washing
Incineration
Bioremediation/S/S
In-situ soil flushing/ln-situ bioremediation
Number of
Sites That
Use It
-7
3
1
5
5
3
1
2
1
1
1
1
1
1
3
2
RELATIVE CONTAINMENT EFFECTIVENESS
Figure* 3-1 a Conceptual Presentation of Remedial Options for Soli and Sediment.
23
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Incineration
Ultra High
Temperature
Processes
Gnomical Ox I dot I
Dehalogenatlo
Hydroprocosaln
Heteroatom
Removal
Hydrolysis/
Neutralization
Ex-sltu
Bio remediation
In-altu
Blorornadlatlon
RELATIVE RESIDUAL PESTICIDE CONCENTRATIONS IN SOILS
FIguro 3-1 b Conceptual Presentation of Remedial Options for Soil and Sediment.
RELATIVE RESIDUAL PESTICIDE CONCENTRATIONS IN SOILS
Figure 3-1 c Conceptual Presentation of Remedial Options for Soil and Sediment.
24
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IMMOBILIZATION OPTIONS
Technologies used for the immobilization of pesticide-contaminated media are categorized and
discussed in this subsection and include containment technologies, S/S technologies, and vitrification.
Containment technologies employ physical barriers (i.e., capping systems, vertical and horizontal barriers)
to reduce the flow of water (through contaminated media) or contaminated groundwater. Stabilization/
solidification and vitrification techniques use chemical reactions and/or physical interactions to retain
contaminants and prevent their migration or interaction with the environment. Immobilization technologies,
except for vitrification (reaction with volume reduction), contain the migration of contaminants, but they do not
reduce the volume of contaminated media or the toxicity of, the contaminant.
Containment Technologies
Containment of contaminant plumes is a common component of the overall remediation of a pesticide-
contaminated site. Containment technologies include both surface capping to limit infiltration of
uncontaminated surface water, and vertical or horizontal barriers within the subgrade to limit lateral or vertical
migration of the contaminated groundwater. Frequently, these technologies are used in conjunction with
groundwater extraction/treatment systems, or as an interim measure to limit pesticide mobilization pending
selection and implementation of a final remedial treatment option.
Capping Systems-
The selection of an appropriate cap design depends upon the remedial objectives, risk factors, site-
specific regulations, and the identified site cleanup goals. Typically, capping systems are used to isolate or
provide impermeable cover to concentrated waste accumulations. However, capping systems may be
appropriate also for limited areas of highly concentrated pesticide contamination, particularly where
groundwater resources and aquifers are at risk from inorganic (WG01) or sparingly water-soluble organic
(WG03) pesticide compounds that can be mobilized by surfaces water infiltration. Capping systems may be
useful in preventing the transport of pesticides in waste groups WG02, WG03, and WG04 that are absorbed
onto colloidal substances. Where remedial treatments are not recommended (because of cost, risk, or
implementation issues), construction of permanent caps may provide long-term, sustained isolation of
pesticide contaminants and prevent mobilization of soluble pesticides.
Capping systems are considered proven technologies for site remediation, but may also represent
a viable interim control option to contain pesticide-contaminated soils and sludges pending selection of final
treatment technologies. Once in place, however, the cap may hinder treatment of the contaminated material.
Capping systems are designed to reduce surface water infiltration, control gas and odor emissions,
improve aesthetics, and provide a stable surface over the waste [2]. They can be as simple as a native soil
cover to more complex full composite barrier covers [3]. The EPA has developed several computer-aided
models to assist in the design and selection of appropriate systems. They evaluate the infiltration, design,
and vegetative cover considerations, and they are available through EPA Risk Reduction Engineering
Laboratory (RREL) in Cincinnati, Ohio. Three types of cap designs are discussed in this section.
• Composite caps are used at regulated landfill closures and other high density waste areas.
• Hardened caps are appropriate in arid climates where the vegetative cover cannot survive
without irrigation, in urban areas where a vegetative cover can provide a visual nuisance, and
industrial areas where the site can be used for parking lots or light construction.
25
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• Multimedia caps isolate soluble contaminants (WG03) from surface infiltration and
subsequent plume migration to underlying groundwater resources or adjacent soils.
Capping alternatives have been selected as part of the ROD at six Superfund cleanup sites primarily
contaminated with pesticides (see Table A-1 in Appendix A), and at one non-NPL site, S&S Flying Service
in Florida (see Table A-2). In all cases, capping technologies were applied as part of a site-wide remediation,
typically in combination with groundwater treatment, vertical containment, and/or remedial activities.
Additionally, capping technologies have been used principally at sites where media are co-contaminated with
pesticide compounds and other wastes and residues.
C_asj£--Cap construction costs are dependent on the number of components in the final cap system.
Cap construction elements and considerations affecting costs are presented in Table 3-2, Significant costs
are associated with the barrier and drainage components. Additionally, costs escalate with increasing
topographic relief. Side slopes steeper than 3H:1V result in stability and equipment operation problems that
can increase the unit costs presented here dramatically.
TABLE 3-2. TYPICAL COST CONSIDERATIONS - CAPS
Technology
Bedding Layer
Gas Collection Layer
Composite Barrier-Clay
Composite Barrier-
Geomembrane
Drainage Layer
Protective Layer
Vegetative Layer
Asphalt Hardened Cap
Concrete Hardened
Cap
Cost Considerations
On-site excavation, hauling, spreading, compaction (labor and eguipment)
• 12-inch granular: Off-site excavation, hauling, spreading, and collector
pipes (labor, equipment, borrow)
• Geonet alternative (single banded-installed)
• On-site excavation, hauling, spreading, compaction (labor/equipment)
• Bentonite board alternative (installed)
• Add for Off-site clay (<20 mile haul)
• Installed - HOPE - 60 mil
- PVC - 40 mil
• 12-inch granular: off-site excavation, hauling, spreading, and collector pipes
(labor, equipment, borrow)
• Geonet alternative (single-bonded, installed)
On-site excavation, hauling, spreading, compaction (labor/equipment)
Topsoil (sandy loam), hauling, spreading, and grading (labor, eguip, borrow)
4-6 inch: exclude protective and vegetative layers, hauling, spreading, rolling of
asphalt
4-inch: exclude protective and vegetative layers, on-site mixing, hauling,
spreading, finishing of concrete, joint sealing
Typical Costs
(1 992$)
$1.00-2.50/yd3
$12.00-18.00/yd2
$0.55/ft2
$2.40-6.00/yd3
$.85/ft2
$8.00-14.00/yd3
$0.50/ft2
$0.35/ft2
$12.00-18.00/yd2
$0.55/ft2
$1.00-2.50/yd3
$1 0.00-1 6.00/yd3
$8.00-1 1.00/yd2
$30.00-40.00/yd2
Data Needs-Data needs relative to capping alternatives are presented in Table 3-3.
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TABLE 3-3. DATA NEEDS FOR CAPPING ALTERNATIVES
Data Needs
Depth to groundwater beneath waste
Availability of cover materials
Rate or magnitude of waste subsidence
Steepness of slopes
Maximum frost depth
Anticipated weather conditions >
Proximity to residential, commercial, or industrial units
Future site land use
Annual/seasonal precipitation rates
Possible Effects
Affects determination of travel time for existing leachate within
the waste mass as well as stormwater infiltration following
capping
Affects costs of capping system construction
Determines the required slope of the cover system and the
grading plan of the landfill surface
May result in movement of cap components relative to one
another at component interface
Influences the thickness of protective cover soil that must be
placed above the underlying soil or other capping system
components
Affects construction of capping system components, e.g., clay
liners cannot be compacted effectively during wet weather
Affects construction noise and dust
Affects the required degree of integrity required of the cap
system and, therefore, construction material selection and
thickness
Affects the quantity of liquid that will penetrate the cap, i.e., cap
design (infiltration of 5% of rainfall volume is considered
unacceptable)
Vertical Barriers (Cutoff Walls) [4,5]--
Vertical barriers are proven technologies that can minimize the movement of contaminated
groundwater off site or limit the flow of uncontaminated groundwater on site when used at the perimeter of a
pesticide remediation area. Common vertical barrier systems include slurry walls placed in excavated
trenches and grout curtain walls formed by injecting grout into soil borings. Groundwater extraction wells are
frequently used with vertical barrier walls to reduce groundwater flow gradients and to recover contaminated
groundwater for treatment. Although they are proven technologies and frequently used, vertical barriers alone
are rarely an effective containment system. Typically, they are used in conjunction with an effective capping
system and/or recovery well system.
Several principal vertical barrier systems have been used extensively to restrict contaminant mobility
and offer varying potential advantages at pesticide-contaminated sites, including.
• Slurry Wall Vertical Barriers: Slurry walls are the most common form of vertical barrier
used on remediation sites; however, typically their use is limited to sites which are relatively
flat and level. High concentrations of electrolytes such as sodium, calcium, and pesticides
containing heavy metals (WG01) in the groundwater can lead to flocculation of the bentonite
from the slurry. Also, pesticides that behave as strong organic or inorganic acids and bases
can dissolve or alter the bentonite or soil component of the trench backfill. Laboratory tests
should be performed to test the site-specific compatibility of the grout.
27
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• Grout Curtain Cutoff Walls: Grout curtain cutoff walls can be constructed by injecting a
grout into soil borings or voids formed as a previously driven steel I-beam is withdrawn from
the subgrade. Such injection methods are usually three times as costly as the slurry trench
method but do not require excavation of potentially contaminated soils or significant work
surface areas. This can be advantageous where exposure to volatilized pesticide
contaminants or remobilization of pesticides may occur during site excavation.
• Sheet Pile Walls: Vertical groundwater barriers have been constructed using driven steel
sheet piling in thousands of conventional construction applications. A large number of
experienced contractors are able to perform this method, and the materials are available
worldwide. However, the carbon steel used in sheet piles can corrode quickly in acidic
conditions, so this method is not recommended at sites with acidic pesticide compounds or
acid comingled wastes.
• Geomembrane Curtains: Geomembranes can be used to form vertical barriers in those
applications where chemical degradation of conventional grouts is anticipated. They can be
used for liners in lagoons and landfills where significant chemical resistance data are
available.
Sjaius_--Vertical barrier techniques have been selected in the RODs of four Superfund sites primarily
contaminated with pesticides. (See Table A-1 in Appendix A.) Most vertical barrier systems are selected for
use with capping and/or groundwater extraction systems to achieve site-wide remediation and to prevent
further contamination. Additionally, french drains and leachate collection are used in conjunction with vertical
barriers to collect mobile pesticides that accumulate at the interface of the barrier and the aquitard or bedrock.
C_osjs.~Construction costs for vertical barriers are influenced by the type of barrier material used and
the method of placing it. The most economical shallow vertical barriers are soil-bentonite trenches excavated
with conventional backhoes, and the most economical deep vertical barrier is a cement-bentonite barrier
placed using a vibrating beam. Significant variations are common in vertical barrier costs due to difficult
groundwater or subgrade conditions. Various vertical barrier technologies and considerations affecting their
costs are presented in Table 3-4.
TABLE 3-4. TYPICAL COST CONSIDERATIONS - VERTICAL BARRIERS
Technology
Soil-Bentonite Slurry Wall
Cement- Bentonite Slurry Wall
Sheet Pile Wall
Cost Considerations
To 30 feet deep
30 to 50 feet deep
50 to 125 feet deep
Vibrating beam prices comparable to soil-bentonite slurry wall.
Injection grouting is 3 to 5 times more expensive than soil-bentonite
slurry wall
Typical Costs
(1990$)
$3.00 to 7.00/ft2
$6.00to11.00/ft2
$9.00to15.00/ft2
Same as above
$16to28/ft2
Data Needs-Data needs and possible effects for vertical barrier alternatives are presented in
Table 3-5.
28
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TABLE 3-5. VERTICAL BARRIER DATA NEEDS
Data Needs
Existing topography
Subsurface stratigraphy
Depth to aquitard or bedrock
Groundwater flow velocities and direction
Chemical characteristics of the leachate
Annual/seasonal precipitation rates
Possible Effects
Affects required depth of slurry wall or grout curtain
Defines Initial need for vertical barrier
Directly affects required depth of the slurry wall or grout curtain
Influences the plan geometry of the slurry wall or grout curtain;
flow velocity affects the quantity of water that can migrate
laterally through the slurry wall or grout curtain
Directly affects materials of construction for slurry walls or
grout curtains
Determines groundwater levels within the subsurface
stratigraphy
Horizontal Barriers-
Horizontal barriers are emerging technologies that act by developing a horizontal barrier to the
downward migration of pesticides and other contaminants, principally to contain the contamination plume or
isolate the underlying groundwater resources. Current feasible technologies are limited to grouting techniques
which reduce the permeability of the underlying soil layers. Several horizontal barrier options are currently
available, including grout injection (vertical and horizontal borings) and block displacement, that may be
effective for reducing the mobility of pesticide contaminants.
• Grout Injection - Vertical Borings: The vertical boring grout injection is applicable to those
pesticide-contaminated sites where an impermeable aquitard is sufficiently near the ground
surface.
• Grout Injection - Horizontal Drilling: The horizontal drilling grout injection is applicable to
contaminated sites where an impermeable aquitard is located too deep to allow the use of
vertical boring grout injection.
• Block Displacement: The block displacement barrier system [6] is a patented technique
that is particularly applicable to those pesticide contamination sites where an impermeable
aquitard is not sufficiently near the ground surface to allow use of vertical barriers.
Status-Horizontal barriers have yet to demonstrate practical applicability and have not been selected
for any sites as a remediation technology. Work by the U.S. Army Corps of Engineers (USAGE) for EPA has
shown that it is very difficult to establish effective horizontal barriers. Studies performed by the U.S. Army
Toxic and Hazardous Materials Agency [7] indicate that conventional grout technology cannot produce an
impermeable horizontal barrier because of an inability to uniformly control the lateral growth of the grout bulb.
Costs-Too few horizontal barriers have been constructed to enable accurate cost predictions. The
costs are influenced mainly by the number of borings that are required. Typical installation equipment costs
range from $1,200 to $3,000 per day. Total horizontal barrier costs may quickly exceed $80.00/square foot
for boring and injection alone.
29
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Data Needs-Data needs and possible effects for horizontal barrier alternatives are presented in
Table 3-6.
TABLE 3-6. DATA NEEDS FOR HORIZONTAL BARRIERS
Data Needs
Existing topography
Subsurface stratigraphy
Depth to aquitard or bedrock
Groundwaterflow velocities and direction
Chemical characteristics of the leachate
Annual/seasonal precipitation rates
Can affect required depth of barrier at given locations, possible
need for specialized grouting equipment
Can influence required depth of horizontal barrier
Can influence depth to horizontal barrier
Affects groundwater flow velocities and direction, influences
quantity of vertical leakage through the barrier
Directly affects selection of grout for horizontal barrier
construction
Determines groundwater levels within the subsurface
stratigraphy
Stabilization/Solidification Technologies
Stabilization and solidification techniques are proven remediation technologies that reduce the mobility
of a contaminant, either by chemically altering or binding it to reduce its mobility (stabilization), or by physically
restricting its contact with a mobile phase (solidification). Solidification also refers to the use of binders for
waste bulking to improve the handling characteristics of liquid or flowable wastes. While stabilization can be
achieved with no solidification, usually solidification is accompanied by some stabilization, i.e., contaminant
or waste interactions with the binder. Like other containment technologies (e.g., capping), S/S technologies
function by limiting the mobility of a pesticide contaminant through environmental media, usually without
toxicity reduction. They can be performed by in-situ or ex-situ application for pesticide-contaminated soil,
sediments, or sludges.
In many cases, the S/S process is applied to the contaminated soils or residues after they have been
pretreated by other technologies such as incineration or soil washing. When incineration is used as the
primary treatment method, the residues may not pass the toxicity characteristic leaching procedure (TCLP)
tests; thus, the S/S process may be applied cost effectively to the residues. Pretreatment by other methods,
such as soil washing, steam stripping, or solvent extraction, may be appropriate prior to the use of S/S,
particularly if the organic content of the contaminated soils is too high to use the process directly.
Applicability-
Treatment by S/S is not a preferred remediation method for organic and alkylated metal pesticides
because the organic fractions can be degraded by biotic and abiotic methods and the possibility exists for
volatilization during treatment. Stabilization/solidification can be helpful when (1) used to control residual
contamination following primary treatment for removal or destruction of organic pesticides and (2) solidification
is used to improve liquid and sludge handling properties prior to remedial treatment. In the first case, metals
are likely to be the residual contaminants since they cannot be destroyed or removed by the primary treatment
process. Organic and inorganic pesticide incineration may result in air emissions of metals, particularly volatile
mercury compounds, that may need to be stabilized in the residues from air pollution control devices.
30
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Metals-Commonly. S/S has been applied to wastes and soils containing regulated metals [8]. Unlike
organic compounds that can be destroyed, metal-containing pesticide compounds (WG01) can be changed
only in oxidation state, chemical species, or physical form. The goal of S/S, then, is to convert the metal to
a less mobile form and physically restrict its exposure to water a.nd air. Cementitious binders are used most
often. In addition to the solidification process, the calcium hydroxide present in these binders may precipitate
many types of metals as sparingly soluble oxyhydroxides, which limits their mobility. Metals can be sorbed
also to the aluminosilicate matrix or replace ions normally present in the crystalline structures of cement.
The high alkalinity that favors precipitation of most metals can be a hindrance to immobilization of
metals that form soluble anionic hydroxides at high pH. For example, cadmium (Cd) can be precipitated at
moderately alkaline pH as Cd(OH)2 but becomes increasingly soluble at a higher pH because an anionic
cadmium hydroxide is formed. Since the pH of minimum solubility is different for each metal, it may not be
possible to form insoluble hydroxides of all metals under one set of conditions.
Pesticide wastes containing alkyl-substituted arsenic or mercury may pose an additional problem
because the organic ligands can increase the volatility of the metallic compounds. Determining the speciation
of metal forms in the waste and mass balances on the metals during treatability tests is important to eliminate
losses. Sulfide additives may be useful in immobilization of mercury.
Another complication in S/S treatment is the speciation of metals in the raw waste. Chromium,
arsenic, and other metals form both soluble cation species and soluble oxyanions (e.g., chromates and
arsenates). These compounds cannot be precipitated as hydroxides and are sorbed differently than cationic
species in a cement matrix. Analysis of raw wastes and their leachates for redox potential and chemical
species is important in designing the most effective immobilization treatment.
Organic Compounds-When remediation alternatives are evaluated during laboratory S/S treatability
tests, there are two considerations for organic pesticides (WG02, WG03, and WG04): (1) immobilization of
the organic contaminant and (2) the organic compounds effects on matrix solidification or immobilization of
other contaminants. Cementitious binders work by surrounding the contaminant and waste particles with an
impermeable matrix. The interior of the cement-based matrix is a high-pH, ionic environment that repels
hydrophobic organic compounds. Lack of affinity between the contaminant and binder precludes the
stabilization of many organics that exists in contaminated soils or wastes.
In addition to possible contaminant/cement incompatibility, heat able to cause the release of volatile
and semivolatiie organics can evolve during the mixing process. Although there are few volatile pesticides,
the heat generated within the cement-stabilized matrix may be sufficient to cause the organic vapors of
concern to be released. Wastes or soils that have been treated for removal or destruction of organic
pesticides may contain some trace amounts of these agents, partial decomposition products, or residual
concentrations of other hazardous organics that require further remediation. High-molecular-weight,
low-volatility residual compounds may be amenable to conventional S/S treatment.
According to some, certain organic compounds will retard or prevent setting (hardening) of typical S/S
matrices. For example, Conner [9] reviewed the available literature related to hazardous waste treatment and
cement chemistry to compile a list of known effects of organic compounds on S/S systems. Many classes
of organics had adverse effects on such factors as set/cure times and cement hydration. Additionally,
properties of the cured product, such as unconfined compressive strength, were affected. To date, no
threshold concentrations have been established regarding interference with conventional binder systems (due
to pesticides or other organic compounds). Certain organic compounds may form soluble complexes with
metals targeted for immobilization. Complex formation can inhibit the contaminant-binder interactions that
provide stabilization and the solidification of metals; whether any pesticides exhibit this tendency is unknown.
31
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Numerous binder and additive systems are designed to overcome the negative effects of organics
on S/S treatment of metals or to immobilize organic contaminants. In the laboratory, modified clays, in which
large organic cations replace exchangeable cations on natural clay, have been proven to sorb several classes
of organic compounds including halogenated phenols [10,11,12]. Halogenated phenols [e.g.,
pentachlorophenol (PCP)] are contained within waste group WG03. These additives can be incorporated with
the normal cementitious matrix for S/S treatment of mixed organic/inorganic wastes. Asphaltic and polymeric
matrices may be suitable for some organic contaminants (possibly including pesticides), but both chemical
treatment and contaminant volatilization during high-temperature processing need to be considered.
Because S/S is not a conventional technology for immobilizing organics, little guidance exists on how
to design such systems. Most data from treatability tests done on mixed organic/inorganic wastes are not
useful, because the necessary measurements (residual organic concentrations in the treated mass and
vapor-phase concentrations during treatment) rarely have been reported. Apparent stabilization, measured
as decreased leachate concentration, actually may be a reflection of significant organic contaminant losses
during treatment [13]. Organics extracted from the treated matrix and identification of low concentrations of
all the organic constituents in a complex extract requires painstaking preparation, method validation, and
quality control. Sims [14] provides an excellent discussion of the mass balance approach for waste treatment
applications and its limitations.
SJitjus-Velsicol Chemical employed a full-scale operation of the solidification process for application
to pesticide-containing waste [8]. Site data related to operations at the Velsicol Chemical site are presented
in Table 3-7. Bench-scale studies of an S/S technology using a cement-base thermoplastic polymer were
conducted at the James River site in Virginia on ketone-contaminated sediments [8]. In the ROD for the
Arlington Blending and Packaging site (Region III), S/S was identified as one of the remediation technologies
for pesticide-contaminated soils (see Table A-1). Two non-NPL sites used S/S alternatives during on-site
removal actions. (See Table A-2 in Appendix A.)
TABLE 3-7. STABILIZATION/SOLIDIFICATION TECHNOLOGY USED
Item
Contaminant
Treatment Volume
Physical Form
Chemical Pretreatment
Binders Added
Volume Increase
Treatment
Disposal
Site Data
Pesticides and orqanics (resins, etc.)
20 million gallons
up to 45% organic
Sludges, variable
No
Portland cement (5 to 15%), kiln dust
Varied, 10% or less
and proprietary agent
In-situ
On-site
Performance-Treatability test data compiled from numerous sources [15] indicate that many types
of metals are amenable to S/S. Whether or not a particular S/S system will perform well on a given
contaminated material must be determined by screening and treatability tests. The information in Table 3-8
is intended to serve as a starting point for designing the test plan for a particular waste.
32
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TABLE 3-8. TREATABILITY TEST RESULTS FOR S/S TREATMENT OF RCRA METALS [15]
Metal Trials
Arsenic
Barium
Cadmium
Chromium
Mercury
Lead
Selenium
Silver
Number of Test Runs
90-100% Reduction
55
14
114
32
16
219
9
16
50-89% Reduction
43
3
32
37
2
87
0
1
<50% Reduction
3
26
26
38
6
84
8
9
Costs-Qualitative screening tests for S/S technology application to a specific site range from $10,000
to $50,000, and are used to establish quickly and inexpensively the validity of alternative technologies in an
application [16]. However, for these technologies, more quantitative bench-scale evaluation costs are typically
higher and more variable depending on the matrix types, binder ratios, and water contents to be investigated.
Associated analytical costs increase dramatically as the number of organic compounds being analyzed is
increased. Total costs of $50,000 or more are not unusual for treatability studies with high associated
analytical costs.
In addition to compliance with contaminant- or site-specific TCLP limits, the screening tests identify
the S/S mix that achieves immobilization at a balance between cost and volume increase. The increase in
volume during S/S treatment can have a significant impact on disposal options, i.e., available on-site space
or transport and landfill disposal cost.
Conner [9] estimated the costs of treatment, transportation, and landfill disposal for some common
S/S systems. Costs ranged from $74 to $397 per ton for on-site landfilling, and from $119 to $517 for
landfilling 200 miles off site. Overall price is dependent on solids volume because more binder is required to
solidify low-solids wastes. Waste products (fly ash, kiln dust) are inexpensive S/S agents if available locally,
but manufactured treatment agents (organic polymers) can be expensive. An accurate cost estimate for
materials, treatment (equipment and personnel), and disposal should be developed during the feasibility study
so that cost factors can be evaluated along with treatment performance.
Data Needs-Data needs and possible effects related to the parameters are listed in Table 3-9 below.
A detailed description of how to evaluate S/S technology as a remedial method for a particular waste is given
in EPA's Stabilization/Solidification of CERCLA and RCRA Wastes Document [8].
33
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TABLE 3-9. DATA NEEDS FOR SOLIDIFICATION/STABILIZATION TREATMENT F17.18 191
Data Needs
Cyanide content
Halide content
Inorganic salts content
Oil and grease content
Organic content
Particle size
Phenol concentration
Semlvolalile organics, polyaromatic
hydrocarbon content
Sodium arsenate, borate, phosphate, iodate,
suilide, sulfate, carbohydrate concentrations
Solids content
Volatile organic concentrations
Coal or lignite content
Effects
Affects bonding (in concentrations >3,000 ppm), interferes with bonding of
waste materials, increases setting time in concentrations > 3,000 ppm
increases setting time; leaches easily
Reduces product strength and curing rates (soluble sails or manganese, tin,
zinc, copper, and lead), reduces dimensional stability of the cured matrix and
leaching potential
Weakens bonds between waste particles and cement in concentrations
>10%
Inhibits setting, curing, and bonding in concentration >20 to 45 wt%
Can inhibit setting, and curing, and bonding (insoluble material passing
through a No. 2 sieve); small particles can coat larger particles, weakening
bonds between particles, cement, and other reagents, affects bonding (<200
mesh or >1/4")
Decreases compressive strength at concentrations >5%
Inhibits bonding in concentrations >10%
Retards setting and curing of cement, decreases final strength of product
Requires large amounts of reagents if solids content is <15%
Volatiles not effectively immobilized, driven off by heat of the reaction
Inhibits setting and curing, reduces product strength
Vitrification Technologies
Vitrification converts waste into a high-strength, glass-like substance. It can treat excavated waste
or soil in situ. In-situ vitrification (ISV) presents two advantages: (1) materials need not be excavated and (2)
they remain buried on site. Vitrification of excavated materials provides improved process control since
volatilized organics and metals can be captured and treated further. Ex-situ vitrification uses plasma arc,
microwave heating, kiln, and other mixed thermal methods to accomplish the conversion. Although it is a
promising technique, particularly for those sites contaminated with inorganic pesticides (WG01), it has not
been used at any Superfund site. However, vitrification has been selected for use at three pesticide-
contaminated Superfund sites:
• Parsons Chemical, Ml - contaminants included chlordane, dioxin, and metals
• Rocky Mountain Arsenal, CO - contaminants included aldrin, dieldrin, endrin, isoclrin, volatile organic
compounds (VOCs), and metals
• Wasatch Chemical, UT - contaminants included chlordane and DDT
In-situ vitrification converts contaminated soils into glass-like materials by passing an electric current,
which generates heat (up to 3,600 °C), through the soil [20]. Because dry soils do not conduct electricity, a
34
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the glass matrix, and many metallic materials fuse or vaporize. The fused waste material then resides in a
chemically inert and stable glass and crystalline mass that has low teachability rates and almost the same
chemical stability as granite. A hood above the treating area draiws off process gases and vapors for further
treatment [21].
Applicability-
Vitrification can treat, destroy, or capture organics (WG02, WG03, WG04) and/or immobilize inorganics
(WG01) in contaminated soils and sludges.
Status--ln-situ vitrification has been selected for soil remediation at three pesticide- (and other
compounds) contaminated Superfund sites. These sites (Parsons Chemical, Rocky Mountain Arsenal, and
Wasatch Chemical) are listed in Table A-1 in Appendix A.
Performance-Tables 3-10 and 3-11 contain experimental results obtained from ISV treatment of
pesticide-contaminated soil during a development and testing program.
TABLE 3-10. PESTICIDE DESTRUCTION/REMOVAL EFFICIENCIES USING ISV F221
Pesticide
4,4 DDD/DDE/DDT
Aldrin
Chlordane
Dieldrin
Heptachlor
Concentration
(PPb)
21-240,000
113
535,000
24,000
61
Percent Destruction
99.9-99.99
>97
99.95
98-99.9
98.7
Percent Removal
>99.9
>99.9
>99.9
>99.9
>99.9
Total
Destruction/Removal
Efficiency (DRE)%
99.9999
99.99
99.9999
99.99
99.99
TABLE 3-11. PERFORMANCE DATA ON IN-SITU VITRIFICATION
Pesticide
Dioxin
Furan
PCB
PCP
Initial
Concentration
(PPb)
>47,000
>9,400
19,400,000
>4,000,000
Destruction (%)
99.9 to 99.99
99.9 to 99.99
99.9 to 99.99
99.995
Costs-Costs for ISV range from $161 to $400 per cubic yard [23,24,25]. A large-scale ISV of 1,300
yd3 of soil was estimated to cost $386/yd3 [24].
Data Needs-Table 3-12 lists data needs for and possible effects of ISV.
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TABLE 3-12. DATA NEEDS FOR IN-SITU VITRIFICATION TECHNOLOGIES [22,26,27.28.291
Data Needs
Whole rock analysis
Vapor passage capabilities of soil
Moisture content
Organlcs content
Overall depth
Depth to groundwater
Presence of drums, sealed containers
Metals and volatile organic compounds (VOC)
content
Presence of debris and rubble
Possible Effects
Silica and oxide composition of rocks and soil determines properties such as
'fusion, ISV melting temperature and melt viscosity, and electrical conductivity
Water vapor generation rates should not exceed ability of dry zone; May
result in operational difficulties; can affect soil processing rates
Increases energy consumption and power costs
Affects sizing and processing capacity of off-gas collection/treatment
equipment at levels above 5-1 0%
Maximum soil processing depth of 20 feet
May require means for removal/recharge limitation such as wells, barrier
walls, or french drains
May interfere with formation and advancement of melt
Presence of VOCs and high mercury, cadmium, and lead soil levels can
result in volatilization and contamination of off-gas which may require
treatment
Affects total processing and treatment costs
DESTRUCTION OPTIONS
The destruction technologies for remediation of pesticide-contaminated soils, sludges, and sediments
are broadly divided into the categories listed below:
• Thermal destruction technologies
• Chemical destruction technologies
• Biological destruction technologies
• Vitrification
Destruction technologies are advantageous because pesticides are removed permanently by reducing
or eliminating toxicity and mobility of contaminants. Although not discussed in this guide, site-specific
regulatory compliance and regulatory disposal criteria for residuals must be addressed. Key issues include
the management and disposal of process residuals (e.g., ashes from incineration) and site-specific regulatory
compliance.
Treatment trains for ex-situ applications typically contain several material handling steps (e.g.,
excavation, dewatering, dredging, conveying, and screening) that are required to prepare and deliver the
contaminated media for destruction treatment. Separation/concentration of the contaminants may be required
as an initial pretreatment to increase the treatment effectiveness of some destruction technologies or reduce
the total volume of materials to be treated.
For in-situ bioremediation and chemical treatment, the media may need to be plowed periodically to
ensure aeration and/or proper contact between the contaminants and the reactants. In-situ treatment requires
proper drainage and recirculation systems to ensure continuous contact between the contaminants and the
reactants.
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Thermal Destruction Technologies
The thermal treatment technologies for contaminated soil, sludges, and sediments can be classified
into two types: incineration and ultra high temperature (e.g., plasma-arc). (Thermal desorption is addressed
in the Separation/Concentration Technologies subsection. Although it is a thermal process, it volatilizes
contaminants from the affected media without destroying them.)
Incineration--
Incineration is a proven, commercially available technology that is being used at several Superfund
sites, including those contaminated with organic pesticides. It is a combustion process whereby thermal
energy and oxygen are applied to a contaminated mass (soil, sludge, and sediments) to oxidize the organic
contaminants which are converted into carbon dioxide, water, hydrogen, chloride, and oxides of nitrogen and
sulfur. Incineration usually consists of a two-stage process. The first is a primary combustion stage that
usually operates in the range of 1,000-1,800 °F and typically evsiporates moisture, volatilizes compounds, and
partially combusts the contaminants. The secondary stage operates in the range of 1,600-2,200 °F and results
in the complete combustion of the contaminants. Off-gases require treatment through air pollution control
equipment such as a venturi scrubber, baghouse, electrostatic precipitator, etc., to remove particulates and
acid gases (e.g., HCI, NOX, SOX, etc.).
Applicability-Incineration technologies can be applied to remediate pesticide-contaminated soils,
sludges, and sediments from waste groups WG02, WG.03, and WG04. Incineration does not destroy inorganic
pesticides (WG01) and it may in fact volatilize metals or concentrate contaminants in ash. It can provide
virtually complete destruction for most pesticide-contaminated media by destroying the organic compounds
and eliminating the waste's toxicity.
Status-Incineration is a proven technology available for full-scale implementation. To date,
incineration has been selected as the remediation technology art 11 pesticide-contaminated Superfund sites
(listed in Table A-1 in Appendix A). (Some of these may be operational or remediated.) Incineration has been
implemented as part of removal action cleanup at three non-MPL sites (listed in Table A-2 in Appendix A).
Rotary kiln, the most widely used incineration type for contaminated soil, has been demonstrated full-scale
for several Superfund sites [30,31,32]. Fluidized bed technology has been successfully demonstrated for a
large PCB-contaminated site in Alaska [33]. Polychlorinated biphenyls (PCBs) are very similar in chemical
structure to chlorinated pesticides like DDT and dichlorodiphenyldichloroethane (ODD) (WG02).
Performance-Incineration technologies demonstrate high efficiencies (greater than 99.99 percent)
for destruction of pesticides in soils [31,32, 32a]. Although data are scarce, the same degree of destruction
efficiency is expected for sediments and sludges. The contaminant destruction efficiency in an incinerator is
dependent on the temperature, residence time, and excess oxygen level. Table 3-13 lists (for several
pesticides) destruction results obtained from three incineration applications.
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TABLE 3-13. INCINERATION DESTRUCTION RESULTS
Pesticide
BHC
DDT
Heptachlor
ODD
2,4-D
2,4,5-T
Initial
Concentration
(ppm)
200
150
30
130
50-3,000
100-510
K.AA
4A1
Final
Concentration
(ppm)
<0.0025
<0.0020
<0.0005
<0.0020
<0.02
<0.002
Mnt HeteptoH
Mnt HotertoH
Removal (%)
99.99
99.999
99.999
99.999
99.96-99.999
99.998-99.999
Process Specifics-Incineration can provide virtually complete destruction of organic pesticides
(typically greater than 99.99 percent destruction) in waste groups WG02, WG03 and WG04 by rupturing and
converting the chlorine and heteroatoms (P, S, N, etc.) to acid gases (HCI, NOX, P2O5, SOX, etc.) and oxidizing
carbon-based molecular structures (either aromatic or aliphatic) to carbon dioxide and water. For pesticides
containing toxic inorganic compounds from waste group WG01, incineration can provide only partial
destruction of the pesticide molecule by destroying any organic portion associated with the heavy metals (As,
cadmium, and lead). During incineration, the volatile heavy metals partition between the incinerator residues
(ash) and the off-gas stream, splitting the contamination between the two phases. Premixing the additives
(lime, alum, etc.) with the soil to suppress heavy metal volatilization has shown limited success [34].
Incineration does not reduce the mobility of the toxic heavy metals from the treated residues, but may actually
cause an increase in the mobility of these metals through off-gas dispersion or improper residual
management.
Generally, incineration requires front-end material handling steps to prepare and feed the
contaminated medium to the incinerator. Sludges may require dewatering, and sediment may require
dredging and dewatering. Aqueous sludge or sediment may be suitable for incineration if they contain a
substantial amount of organic matter. However, the large amount of energy required to evaporate the water
may make the incinerator energy-inefficient and necessitate adding a front-end dewatering step. Wastewater
treatment or discharge options are required where front-end dewatering steps are incorporated into the
treatment train for sediments and sludges. Incineration of pesticide-contaminated media requires air pollution
control to scrub the off-gas particulates and neutralize the acid gases. After proper analysis, such as the
(TCLP) test for metals, the incinerator residue (ash) may be disposed in an approved landfill if it is below
levels considered hazardous to human health and the environment. Figure 3-2 is a schematic diagram of a
typical incineration treatment train.
Several types of incinerators can be used. A rotary kiln incinerator is a cylindrical refractory-lined
shell that is mounted at a slight incline. Rotary kiln incinerators are versatile units that can incinerate solid
waste, heavy tar, sludges, waste drums, and liquid wastes. A fluidized bed incinerator consists of a vertical
refractory-lined vessel that contains a bed of inert sand-like material. An upward flow of air through the bed
results in turbulent mixing and causes fluidization of the bed material. (Solids, liquids, or sludges can be
ignited directly into the bed or at its surface.) A circulating bed cumbustor is similar to the fluidized bed
incinerator, but it uses higher velocity air and circulating solids to create a larger and higher turbulent
combustion zone for increased combustion efficiency.
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Soils, sludges, and sediments containing a high concentration of alkali metals (e.g., Na or K) can
cause a severe refractory attack and form a sticky, low-melting eutectic compound which can cause
plugging in the air pollution control system. The heating value of the feed material affects the feed
capacity and the fuel usage of the incinerator. The heat content of the contaminated media can limit the
incinerator feed processing rate and bulk efficiencies. Chlorinated pesticides generally require a higher
temperature (>1,800 °F), longer residence time (>2 seconds), and 30 to 100 percent excess oxygen to
achieve high destruction efficiencies.
are:
Incineration of soils, sediments, and sludges generates four major effluent/residual streams. They
• Ash (treated medium) and solid residuals from the air pollution control system
• Wastewater from the air pollution control system if wet and caustic scrubbing is used
e Off-gas emissions from the air pollution control system
• Contaminated wastewater (from the dewatering step)
The ash and the solid residues can be reclaimed after proper analysis. The scrubber wastewater
can be treated further on-site (e.g., by neutralization and carbon adsorption) or pretreated and discharged
to a publicly-owned treatment work (POTW). The off-gas streams may require continuous monitoring.
Air-Operated
Sludge/Sediment
Transfer Pump
t
I
Sludge/Sediment
Dewatering Unit
Filtrate to
Additional
Treatment
Dewaterad
._ — „ Sludge/
Contaminated M Bypass Sediment
f e Sludge or Sediment
-------
Data Needs-Implementation of incineration technologies requires extensive physical and
chemical characterization of the contaminated medium parameters. Data needs and possible effects
related to these parameters are presented below in Table 3-14.
TABLE 3-14. DATA NEEDS FOR INCINERATION [26,36]
Data Needs
Moisture content
Ash content
Ash fusion temperature
Particle size (fines)
Heating value (BTU content)
Waste matrix characteristic
Metals
Hatogenated organic compound
concentration
Potassium and sodium and organic
phosphorous
PCBs and dioxln
Possible Effects
Higher moisture content affects heating value and material handling steps.
Determines the amount of residual material requiring disposal or additional
treatment
Can cause inorganic salts to melt, resulting in slagging and damage to refractory
Oversize material may require size reduction and may hinder processing; Fines
cause high particulate loading in the off gas stream
Auxiliary fuel is required to incinerate waste with heating value of <8,000 BTU
May require separation to remove oversize pieces or debris; muddy soils or wet
sludges may require pretreatment to prevent feed system pluqqinq
May require ash and flue gas treatment to immobilize or remove
Forms acid gases which may attack refractory material and/or impact air
emissions
Can cause severe refractory attack and slagging; may require blending of feed
stock to reduce levels of these substances
May require higher temperatures and longer residence times to achieve
adequate destruction efficiency
Ultra High Temperature Process-
Ultra high temperature process, e.g., plasma-arc, is an emerging ex-situ technology that uses
electrical energy to generate ultra high temperatures to destroy toxic organic compounds. The
contaminant mass is heated to an extremely high temperature (3,500 to 10,000 °F) where the organic
compounds are broken down to elements, and elemental oxides are transformed into gaseous and ionized
phases. The detoxified ionized phase reactor effluents require recombination and treatment through air
pollution control equipment before discharge through a stack. Plasma-arc destruction can be performed in
a single or multistage reactor. This technology has not been used on pesticides or in a full-scale
remediation but has the potential to be an effective technology for organic pesticides. Due to the higher
temperatures achieved in this technology (related to incineration), it is likely that more complete
destruction of chlorinated pesticides and other refractory compounds will occur.
Applicability—Ultra high temperature processes can be applied to remediate soils, sludges, and
sediments contaminated with pesticides in waste groups WG02, WG03, and WG04. Conceivably, the
plasma-arc technology, can provide the highest degree of destruction on pesticides when compared to the
other technologies discussed above.
Status-To date, plasma-arc technology has no demonstrated application for pesticide-
contaminated media; however, the technology has been demonstrated successfully in the remediation of
PCB-contaminated soils and dioxins [37]. No ROD has been issued which calls for the use of plasma-arc
or other similar high temperature processes at a pesticide-contaminated Superfund site.
40
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Performance-The plasma-arc has been demonstrated for PCB- and dioxin-contaminated soils at
Bloomington, Indiana, and the Love Canal site, New York. In both of the applications, a destruction
efficiency of 99.9999 percent was achieved [37]. Currently, performance data for this treatment (as used
on pesticide-contaminated soils) is not available. However, they should be similar because of the likeness
between PCBs and chlorinated pesticides.
Process Specifics-Plasma-arc technology can be applied to destroy pesticide molecules. Like
other thermal treatment technologies, application of plasma-arc requires front-end material handling steps
to prepare and feed the material to the reactor. A front-end extraction/concentration step is required for
soils and nonpumpable sludges. The treated media can be returned for reclamation. The schematic of a
typical treatment train for plasma-arc destruction is very similar to that of incineration (see Figure 3-2).
Plasma-arc requires more rigorous off-gas cooling, condensation, and recovery units than incineration.
The gaseous effluent from the plasma-arc reactor requires quenching and treatment using air
pollution control equipment. The acid gases (HCI, SO2, NOX) generated from pesticide destruction require
neutralization before emission through a stack. The acidic scrubber water must be neutralized and then
discharged to a POTW or disposed of off site according to regulatory guidelines.
Dste-Dewatering and excavation must be carried out in preparation of contaminated soils in the
pretreatment phase. Air pollution control, management of scrubber effluent, and ash disposal costs are
factors that should be considered in the post-remediation phase. Factoring the pre- and post-treatments,
typical plasma-arc destruction costs could be greater than $1,000 per ton (1991).
Data Needs-Implementation of this technology requires extensive physical and chemical
characterization of the contaminated medium. The concentration of pesticides and the physical form of
the contaminated medium determines if the technology should be applied directly to the contaminated
medium or to a solvent extract phase rich in pesticide concentration. The selection of the medium to be
treated is influenced by the relative costs associated, such as media pretreatment requirements, need for
auxiliary supplements, process efficiency, etc. Data needs and possible effects related to these
parameters are similar to those required for incineration. (See Table 3-14.) The ionization temperature
and potential of the contaminants are also significant factors that alter the effectiveness of ultra high
temperature processes.
Chemical Destruction Technologies
The chemical destruction technologies with potential application for ex-situ remediation of
contaminated soil, sludges, and sediments are as follows:
• Chemical oxidation
• Dehalogenation/hydrodehalogenation
• Hydroprocessing/heteroatom removal
• Hydrolysis/neutralization
Chemical Oxidation--
Chemical oxidation is an innovative technology that has been used at three pesticide-
contaminated sites. The process oxidizes organic contaminants through the addition of chemical oxidizing
agents (such as ozone or hydrogen peroxide) which liberate free radical oxygen. Chemical oxidation is
enhanced by the presence of heat and a catalyst. The catalysts used are typically metals, namely Fe, Al,
Cu, etc. Additionally, ultraviolet radiation is used often to facilitate the oxidation process, but only in the
aqueous phase. The presence of photosensitive material (e.g., TiO2) during oxidation can enhance
significantly the oxidation of highly halogenated organic contaminants. Catalytic or photocatalytic
oxidation C9nverts organic contaminants to products like CO2 and H2O. The chlorine and heteroatoms (N,
P, S, etc.) present in the organic molecule are converted to acid gases like HCI, SOX, NOX or P2OS, etc.
Chemical oxidation can be carried out in reactor configuration in aqueous or slurry phase. Generally,
chemical oxidation units do not require extensive air pollution control equipment.
41
-------
Applicability-Chemical oxidation can be used to treat soils, sludges, and sediments contaminated
with pesticides from waste groups WG02, WG03, and WG04. Since it is a nonselective treatment
technology, oxidation is not well suited for high strength complex waste streams. This results in a relatively
large chemical demand [26,38]. Catalytic oxidation may provide a high degree of destruction of organic
pesticides. This destruction can reduce greatly the toxicity of the pesticides within the treated medium.
However, the possible formation of hazardous intermediate compounds due to partial oxidation of
pesticides should be considered.
Status-Chemical oxidation is a proven technology that has been used by the chemical process
industry. However, its application in environmental remediation has been limited thus far. To date,
chemical oxidation (as a remediation technology) has been used at three non-NPL sites only, listed in
Table A-2 in Appendix A. Field testing at a U.S. Air Force base site has demonstrated successful
photolytic oxidation of the herbicide Agent Orange [39]. Various versions of chemical oxidation technology
have been tried on a bench and pilot scale [40 through 43].
Performance-Contained in Tables 3-15 and 3-16 are data that illustrate reductions in pesticide
levels achieved using several oxidation methods.
TABLE 3-15. REDUCTIONS IN PESTICIDE LEVELS ACHIEVED USING OXIDATION METHODS
Oxidation
Technology
Photocatalytic
Ozone
Fenton's Reagent
Acid
Pesticide
2,4 -D
2.4,5 -T
Undane
Aldrin
Dleldrin
PCP
Initial
Concentration
(ppb)
490
977
.
-
-
-
Final
Concentration
(ppb)
82
31
.
-
-
.
% Removal
83.3
96.8
75
100
100
79.5
Reference
32
34
36
TABLE 3-16. EFFECT OF UV OXIDATION ON CARBOFURAN AND MALATHION [42]
Pesticide Concentration (ppm)
10
10
Oxidation Time (min)
22
66
% Removal
90
Process Specifics-Catalytic/photocatalytic chemical oxidation can be performed in a slurry ,
reactor. Unlike dehalogenation, chemical oxidation can accomplish a high degree of destruction by
rupturing the aromatic ring to produce CO2 and H2O while at the same time converting the chlorine and
heteroatoms (N, P, S) to acid gases (HCI, NOX, P2OS, SOX, etc.). The decision to apply the technology
(direct treatment vs. extract phase treatment) is site-specific, and the impact on relative costs and
attainment of desired cleanup levels must be investigated thoroughly before implementation. Figure 3-3 is
a schematic diagram of a treatment train in which catalytic oxidation destruction technology is the primary
treatment process.
42
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Catalytic/photocatalytic chemical oxidation can be carried out with a variety of oxidants, namely
hydrogen peroxide (H?O2), O3, fluorine, hypochlorite, nascent oxygen, etc. Although fluorine has the
highest relative oxidation power, it is not widely used because of associated hazards. A widely used and
effective combination is reaction between ferrous ion (Fe++) and H2O2, which liberates the hydroxyl (OH')
free radical. The hydroxyl free radical has the second best oxidizing power after fluorine and provides an
effective oxidation reaction. Additionally, the OH' radical can be .generated by the photolysis of H2O2 by
UV light. The presence of a photocatalyst (e.g., TiO2) during OH' formation enhances the rate of oxidation
by several fold [43]. The catalytic/photocatalytic oxidation process is dependent on concentration and
temperature. Neutral to slightly acidic pH (6 to 7) and elevated temperature (50 to 80 »C) produce higher
oxidation efficiencies for chlorinated organics (WG02 and WG03).
Ozone is an oxidant with a pungent odor that is utilized in the oxidation process. Since it
decomposes rapidly, it must be generated on site prior to application. Ozone's rate of decomposition is
strongly influenced by pH. Pesticides that are highly halogenated are difficult to oxidize with ozone.
If properly engineered and applied, catalytic and photocatalytic oxidation can reduce significantly
the toxicity, mobility, and volume associated with the pesticide contaminants. Following ex-situ oxidation,
the treated soils, sludges, or sediments may require washing and dewatering prior to reclamation and
catalyst recovery for reuse. The washwater/filtrate can either be recycled for reuse or disposed of in
accordance with regulatory guidelines.
-------
Costs-ln the pretreatment phase, plowing, excavation, dewatering, dredging, conveying, screening,
and size reduction may be necessary. For the post-treatment phase, washing, dewatering, and disposal or
replacement are necessary. Including these, estimated costs range between $200 to $300 per ton and $50
to $100 per ton, respectively, for ex-situ and in-situ modes of treatment [24,35].
Data Needs-Data needs and possible effects related to these parameters are listed in Table
3-17, below.
TABLE 3-17. DATA NEEDS FOR CHEMICAL OXIDATION [26,38]
Data Needs
PH
Clay, silt, and humlc content
Contact time
Number of Contaminants
Moisture content
Presence of chromium (+3), mercury, lead, and
silver
Oxidation potential
Pesticide photosensltlvlty
Reaction type: exothermic vs. endothermic
Oil and grease content
Chlorinated organlcs
Possible Effects
Process requires optimum pH; suboptimal pH may inhibit oxidation
reaction and result in need for additional treatment
Increases reaction time and temperature
Must be sufficient to allow maximum effectiveness of oxidant(s) used
Complex wastes containing large numbers of contaminants may require
excessive amounts of chemicals
Soils or sludges containing solids levels greater than approximately 3%
may require moisture addition to allow intimate contaminant-oxidant
contact
Oxidation of organic sludges will oxidize these metals to their more toxic
and mobile forms
Affects the driving force and rate of the chemical oxidation reactlon(s)
Affects the tendency of a pesticide to oxidize as a result of exposure to
light
If exothermic, no or little energy input is required; if exothermic, energy
input (heat, light, etc.) is required.
Oil and grease concentrations greater than 1% interfere with contaminant-
oxidant contact
Requires excessive reagent, temperature, and catalyst
Dehalogenation/Hydrodehalogenation--
Dehalogenation is a chemical detoxification process that removes and/or substitutes halogen atoms
from an organic molecule. When hydrogen is used as a means for halogen atom substitution, the process
is referred to as hydrodehalogenation. In halogenated toxic organic compounds, the halogen atoms are
typically the primary source of toxicity. Dehalogenation/hydrodehalogenation removes the toxicity associated
with the halogenated atoms. Dehalogenation/hydrodehalogenation processes can be applied to contaminated
media by the introduction of chemical reagents and catalysts over a wide pH and temperature range. If the
contaminants are to be hydrodehalogenated, a source of hydrogen is required.
Dehalogenation/hydrodehalogenation can be applied in a slurry or aqueous phase reactor configuration.
Dehalogenation processes generally do not require extensive air pollution control equipment.
Applicability-Catalytic dehalogenation/hydrodehalogenation can be applied to treat soils, sludges,
and sediments contaminated with chlorinated pesticides in the waste groups WG02 and WG03. Some
examples of WG02 group pesticides that could be remediated by this technology are DDT, DDE, lindane,
toxaphene, heptachlor, aldrin, and dieldrin. Examples of WG03 group pesticides are ethylene dibromide,
chlorpicrin, and 2,4-D. These technologies can provide only partial destruction by removal of the halogen
atom (e.g., CI).
44
-------
Status-Catalytic dehalogenation/hydrodehalogenation is an innovative technology. To date, this
technology has been selected for use at two non-NPL sites (listed in Table A-1 in Appendix A) for the
remediation of pesticides. It has been tested, mainly on a bench scale, to treat pesticides in a soil medium.
Additionally, catalytic dehalogenation has been widely tested in pilot-scale studies to treat PCB-contaminated
soil [44]. A Superfund site, Wide Beach Development in New York, used the chemical dehalogenation
technology [potassium hydroxide/polyethylene glycol (KPEG)/alkaline metal hydroxide/polyethylene glycol
(APEG)] as a full-scale remediation technology to treat PCB-contaminated media. The applicability of this
technology to organics like PCBs indicates that it may be applicable to organic pesticides. Nascent state
hydrodechlorination (NSH), a form of hydrodehalogenation technology, has been tested on a field scale [45].
Results indicate essentially complete conversion of endrin and partial conversion of dieldrin to significantly
less toxic chemical compounds [45].
Performance-Contained in Table 3-18 are the results of several tests in which variants of the
hydrodechlorination technology were evaluated for pesticide-contaminant soils.
TABLE 3-18. HYDRODECHLORINATION RESULTS
Hydro-
dechlorination
technology
Zn/acid/acetone
Zn/acid/catalyst
NaBH4/Ni,N
Pesticide
Dieldrin
Endrin
DDT
Lindane
Initial
Concentration
(ppm)
.
>7,000
-
Filial
Concentration
(ppm)
-
<1
-
% Removal
>90
>90
99.99
100
Reference
45
46
47
Process Specifics-Full-scale application of dehalogenation/hydrodehalogenation technology requires
front-end material handling steps such as excavation, dewatering, or dredging. Excavation is required for
soils, whereas sludges may need dewatering and sediments require dredging. The media is conveyed near
the reactor where additional material handling steps such as size reduction and screening/classification may
have to be performed to separate large objects (stones, rubble, etc.) to protect the reactor. Figure 3-4 is a
schematic diagram of the treatment train for the ex-situ dehalogenation/hydrodehalogenation treatment
process.
Dehalogenation/hydrodehalogenation can be performed in a slurry reactor configuration. Catalytic
chemical dehalogenation/hydrodehalogenation removes the chlorine atoms from aromatic chlorinated
pesticides (WG02). Removal of chlorine atoms partially detoxifies the pesticides. However, the
dehalogenation normally does not destroy the ring structure of the pesticides which may contribute to the
residual toxicity remaining in the treated soils/sludges/sediments. Site-specific treatability studies are needed
to determine if additional treatment is necessary.
When used in conjunction with the solvent extraction or soil washing separation process,
dehalogenation/ hydrodehalogenation can be applied to the extract phase rich in concentrated pesticides
removed from soils, sludges, or sediments. However, for some types of dehalogenation/hydrodehalogenation
technologies, an initial separation/concentration step may not increase the treatment effectiveness and only
add additional cost and technical difficulties.
45
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Chemical dehalogenation (KPEG/APEG) is an innovative technology that uses alkaline reaction
conditions to detoxify the pesticides. The contaminated medium is allowed to react with a mixture of
potassium hydroxide (KOH) and polyethylene glycol (PEG) in the presence of a co-solvent, namely, dimethyl
sulphoxide (DMSO). The reactor contents are heated to an elevated temperature (150 to 180 °C) for a few
hours. After the reaction is complete, the contents are filtered and washed at least three times to remove the
residual reactants which can either be recycled and reused or disposed of following regulatory guidelines.
The treated media are analyzed for TCLP and Treatment Work Approval (TWA) components before
reclamation.
The KPEG total waste analysis removes chlorine atoms from the pesticides present in the
soil/sediment/sludges. For some pesticides in waste group WG02 (e.g., DDT, DDE, etc), KPEG has
demonstrated 99.99 percent dechlorination efficiency [46]. The dechlorination effectiveness of KPEG
technology is influenced minimally by variations of pH, moisture, and clay content,of the soils, sludges, and
sediments. KPEG-type dechlorination technology cannot remove heavy metals (e.g., Pb, As, or Cd) in
pesticide group WG01 which may be present as co-contaminants in the media. However, the KPEG
dehalogenation.treatment substantially can reduce the toxicity resulting from pesticides of waste group WG02
and WG03.
An emerging chemical hydrodehalogenation technology, NSH has shown promising results for the
treatment of soils contaminated with DDT and DDE (WG02) [45,46]. The process^uses zinc (Zn) and an
organic acid to generate nascent hydrogen which selectively replaces the chlorine atoms from the pesticide
molecule. A metallic catalyst (e.g., Ni) that occludes hydrogen effectively catalyzes the reaction. The process
can be performed in a reactor configuration where the contaminated soil, sludge, or slurry can be mixed with
Zn, acid, and catalyst. Typically, the reactants are heated to 80 to 95 °C for 2 to 6 hours. It produces
numerous intermediate products, such as zinc salts, which require additional studies to determine a method
for their safe removal. The potential for hydrogen gas release also presents a danger and may affect the
viability of this technology. Like KPEG, NSH type treatments may be applied effectively to soils, sludges, or
sediments. The front-end material handling and post-treatment operations are expected to be similar to KPEG
treatment.
Nascent state hydrodechlorination has achieved 99.99 percent efficiency in hydrodechlorinating
pesticides in waste group WG02. It can remove both aliphatic and the aromatic chlorine atoms. Its treatment
efficiency is minimally influenced by the physical characteristics of the environmental media (e.g., pH, particle
size, moisture, and clay content). One advantage of NSH over KPEG is the use of acidic reaction conditions
which permit concurrent leaching of heavy metals contaminants while hydrodechlorinating the pesticides. This
process, like KPEG, significantly reduces the toxicity of the treated media but may not reduce greatly the
environmental mobility of the pesticide residual.
Sodium borohydride hydrodehalogenation is an emerging technology that uses sodium borohydride
(NaBH4) to detoxify chlorinated pesticides. Sodium borohydride provides the source of hydrogen that
selectively replaces the chlorine atoms from the pesticides. The efficiency for hydrodehalogenation has
approached 100 percent for chlorinated pesticides like lindane using nickel boride catalyst [47]. The treatment
can be performed in a reactor configuration similar to KPEG or NSH treatment. The pre- and post-treatment
unit operations are expected to be similar to treatment trains used in KPEG and NSH technologies.
Borohydride hydrodehalogenation has been demonstrated in soil medium for treatment of paraquat for a small
scale in-situ application. NaBH4 was added to the soil using an alkaline solution containing NaOH.
The borohydride hydrodehalogenation can be applied to soils, sludges and sediments. Dewatering
may not be necessary for treatment of sludges and sediments since the process is carried out in slurry phase
containing water. Like KPEG, the NaBH4 process is not expected to remove heavy metal co-contaminants
present with the pesticides. NaBH4 treatment can significantly reduce the toxicity of the treated media but may
only achieve limited mobility reduction of residual pesticide contaminants.
46
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Sludgo/Sadlment
-Tr«n»Tor F»ump
Excavation
&. Mixing
Equipment
Atmonpriore
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Ado.orbc.i-a I *
|
; .'••^ll>'t: '•'-.' I-r. "-.:•": •-•/..
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, ,
fc I J-CT-l
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F=I0uro 3-4 Schema*!
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;ic_Toi- Dohalogoncatl^on oT
Cosls-ln the pretreatment phase, plowing, excavation/dewatering, dredging/conveying,
screening/size reduction or separation of soil are required costs. In the post-treatment phase washing,
dewatering, disposal, and recycling are cost factors. Typically, dehalogenation/hydrodehalogenation costs
$200 to $300 per ton and $50 to $100 per ton, respectively, for ex-situ and in-situ modes of treatment (1991
$).
Data Needs-Data needs and possible effects related to these parameters are listed in Table 3-19
below. Another factor that may alter the effectiveness of dehalogenation is the redox potential of the
contaminants.
TABLE 3-19. DATA NEEDS FOR
DEHALOGENATION/HYDRODEHAI.OGENATION [19,26]
Data Needs
Moisture content
pH
Clay, silt, and humic content
Chlorinated organic content
Aliphatic organics, inorganics, and metals
Aluminum and other alkaline reactive materials
Particle size
Redox potential
Possible Effects
Pressure of moisture levels greater than 20% require excessive amounts
of reagent since water reacts with and dilutes the reagent; higher
moisture content also increases feed handling and energy requirements
May require additions of large amounts of alkali to achieve optimum pH
since process operates under highly alkaline conditions
Increases reaction time due to binding of contaminants
May require excessive amounts of reaqent in concentration > 5%
Technology is effective only with aromatic halides
May increase reaaent demand
Oversized material may hinder processing and size reduction
Affects the driving force and rate of the reaction
47
-------
Hydroprocessing/Heteroatom Removal-
Hydroprocessing/heteroatom removal, an emerging technology, is an ex-situ chemical detoxification
process for the removal and/or substitution of the chlorine and heteroatoms (N, P, S, etc.) present in an
organic or organometallic contaminant, detoxifying the molecule. This technology, although not yet selected
for a full- scale pesticide remediation, has the potential to be an effective pesticide remediation technology.
Hydroprocessing, a broader version of hydrodehalogenation, can be performed with either atomic or molecular
hydrogen. Hydroprocessing is applied in reactor configuration to a contaminated medium by the introduction
of a liquid that solubilizes the contaminants. Gaseous hydrogen and a catalyst are introduced to the mass
and the contents are heated under pressure. Under the operating condition, the heteroatoms present in the
contaminant are removed selectively and replaced with hydrogen. Like dehalogenation processes,
hydroprocessing generally does not require extensive air pollution control equipment.
Applicability-Catalytic hydroprocessing is a broader version of catalytic hydrodehalogenation
technology and is capable of removing a wide range of heteroatoms from pesticide molecules. This
technology is applicable for treatment of pesticides in the waste groups WG02, WG03, and WG04. Catalytic
hydroprocessing can be applied to soils, sediments, and sludges in the ex-situ mode of treatment. The pre-
and post-treatment unit operations are similar to those required for catalytic dechlorination/hydrodechlorination
technologies. Catalytic hydroprocessing requires a source of molecular hydrogen (H2) at the treatment site.
It is a partial detoxification technology because it cannot destroy the ring structure of aromatic organic
pesticides. The treated media may require further detoxification/immobilization treatment.
SlatUS-Hydroprocessing technology is used widely in petroleum refining to remove heteroatoms from
crude oil. It is a viable yet undemonstrated process for pesticide remediation. Hydroprocessing has been
demonstrated successfully in bench-scale studies for chlorinated base/neutral/acid-extractable compounds
(BNAs) (such as chlorobenzene, etc.), which are chemically similar to pesticides in the waste groups WG02
and WG03 [48]. Additionally, a novel version of the technology has been demonstrated in bench scale studies
for a wide variety of pesticides [49]. While this technology has potential effectiveness for pesticide
remediation, no ROD for this technology has been issued to remediate pesticide contamination at Superfund
sites.
Performance--ln a bench-scale study, chlorinated pesticides were hydroprocessed with liquid
ammonia-alkali metals. The treatment showed nearly complete dehalogenation (i.e., removal of chlorine
atoms from the ring structure) of the chlorinated pesticides [49].
Process gpecifjc?--Like catalytic hydrodechlorination, this technology can be applied in reactor
configuration using a three-phase heterogeneous catalytic reaction. The contaminated soil is mixed with a
solvent that solubilizes the pesticides and brings them in close contact with gaseous hydrogen. The gaseous
hydrogen can either be fed from an external source or generated in a reactor by reaction between liquid
ammonia and metallic sodium [49]. Catalytic hydroprocessing, like hydrodehalogenation, cannot destroy the
ring structure of the organic pesticides. As a result, catalytic hydroprocessing cannot accomplish complete
destruction of the pesticides; however, depending on their type and structure, the toxicity can be reduced
substantially. The destruction efficiency for hydroprocessing is expected to be marginally dependent on the
moisture, pH, clay, and humic content of the soils, sludges or sediments. Trace quantities of heavy metals
in the media may serve to catalyze hydroprocessing.
Cjssls-Plowing, excavation/dewatering, dredging/conveying, and screening of the soil must be carried
out in the pre-treatment phase. In the post-treatment phase, washing, dewatering, disposal and recycling of
the catalysts must be performed. Including the pre- and post-treatments, estimated typical cost for ex-situ
operation range between $200 to $300 per ton (1991 $).
Data Needs-Data needs and possible effects for hydroprocessing are noted in Table 3-20.
48
-------
TABLE 3-20. DATA NEEDS FOR HYDHOPROCESSING [19,26]
Data Needs
Hydrogen consumption
Reaction products
Elemental analysis (N, P,S, Cl, etc.)
Nature of reaction
Optimum reaction conditions
Moisture content
Possible Effects -
Depends on type and concentration of contaminant(s) present;
affects treatment costs
Incompletely reacted or destroyed contaminants may form
reaction products that exhibit toxicity
Affects hydrogen requirement
Dictates selection of chemical reagents and process control
variables!
Required in order to achieve most efficient reaction rates and
lowest costs
May require removal of water due to possible incompatibility
with chemical reagents, e.g. metallic sodium; presence of water
may present safety problems and result in excessive reagent
usage
Hydrolysis/Neutralization-
Hydrolysis/neutralization, an emerging technology, is a chemical treatment process that uses aqueous
acidic or alkaline solution to decompose organic and inorganic contaminants, yielding smaller innocuous
molecules. This technology may only have limited potential as a pesticide remediation technology.
Hydrolysis/neutralization reactions can be enhanced by the presence of heat and catalyst. Incomplete or
improper hydrolysis of contaminants can often produce by-products that are more toxic than the initial
contaminants. Hydrolysis/neutralization treatment can be performed in either in-situ or ex-situ mode of
treatment. Ex-situ hydrolysis can be performed in reactor configuration. Hydrolysis/neutralization treatments
generally do not require extensive air pollution control equipment.
Applicability-Hydrolysis/neutralization technology can be used to detoxify pesticides in waste groups
WG03 and WG04 and can be applied to treat soils, sludges, or sediments.
Status-The hydrolysis/neutralization process has been demonstrated on both bench- and field-scale
studies with limited success [50,51]. No vendor information is currently available regarding the marketing of
the technology. To date, no ROD has been issued for cleanup of any pesticide-contaminated site using
hydrolysis/neutralization.
Performance-Table 3-21 contains the results from hydrolysis treatment of pesticide-contaminated soil.
TABLE 3-21. RESULTS FROM HYDROLYSIS TREATMENT OF PESTICIDE-CONTAMINATED SOIL
Pesticide
Methyl parathion
Ethvl oarathion
Reduction {%)
98
76
Reference
50
—
49
-------
Process Specifics-Hydrolysis/neutralization reactions are influenced by pH, temperature, degree
of sorption on the contaminated media, and presence of other compounds that might act as catalysts.
Generally, organophosphorus pesticides and carbamate pesticides (WG04) can be degraded by
hydrolysis under alkaline conditions. Malathion, parathion, and methyl parathion (WG04) have been
degraded by alkaline hydrolysis processes. Figure 3-5 shows a schematic of an in-situ treatment train
using hydrolysis/neutralization technology as the primary destructive treatment.
Incomplete or improper hydrolysis due to poor contact or choice of improper reagent or catalyst
may produce reaction byproducts equal to or more toxic than the original pesticide contamination. It is
prudent to note that the inorganic pesticides cannot be detoxified by the hydrolysis process because of the
presence of toxic heavy metals. When reacted with dilute acid, inorganic pesticides such as lead arsenate
and zinc phosphide in WG01 can form hydrogen (H2) gas and metal hydrides (AsH3, PH3). The gas is
explosive and the hydrides produce toxic fumes. When these pesticides are reacted with alkaline solution
(NaOH), the acidic components (As, P, etc.) are neutralized and convert to sodium arsenate and sodium
phosphate types of compounds.
Hydrolysis/neutralization can be influenced considerably by the pH, moisture, clay, and humic
contents of the soil, sludge or sediment. The pre- and post-treatment unit operations for application of this
technology are similar to those used for catalytic dehalogenation or catalytic hydroprocessing. The
residual streams from post-treatment operations can either be recycled for reuse or disposed of following
regulatory guidelines.
_'eisrt Wator
to Disposal
>r Further
Contaminated
Q round wettor
Extraction
Wolis
Satu retted
Figure 3-S Schematic for Hydrolysis/Neutralization CI«-Sltu>
of Peatlclde-Gontamlnated Soils.
, excavation, dewatering, dredging/conveying, screening, and separating methods
must be carried out for the preparation of the soil. Air pollution control, washing, dewatering, disposal and
recycling facilities must be included in the post-treatment phase. Factoring the pre- and post-treatment
activities, typical costs involved are $150 to $250 per ton and $50 to $100 per ton, respectively, for ex-situ
and In-situ modes of treatment (1991 $).
Data Needs-Data needs and possible effects related to these parameters are listed in Table 3-22,
below. Other factors that may affect the applicability of this technology include the nature of the resulting
reaction products and whether the reaction is exothermic or endothermic in nature.
50
-------
TABLE 3-22. DATA NEEDS FOR HYDROLYSIS/NEUTRALIZATION [18]
Data Needs
PH
Contact time
Chemical Reagent
Moisture content
Clay, silt, and humic content
Chlorinated organic content
Possible Effects
Suboptimal pH may inhibit reaction and result in need for additional
treatment; acid or alkaline reaction conditions may require specialized
materials of construction for equipment.
Must be sufficient to allow maximum effectiveness of chemical reagents
used
Physical state (solid or liquid) influences material handling and processing
equipment needs
Determines reagent requirements
Increases reaction time requirements
Requires addition of excessive amounts of reagent due to increased
demand
Biological Destruction Technologies
Bioremediation/Microbial Degradation-
Bioremediation (also known as microbial degradation or biodegradation) is an innovative
technology that has been selected 'for the remediation of one NPL and two non-NPL pesticide-
contaminated sites. This is a destruction process for treatment of media contaminated with low levels of
toxic organics. Microbial degradation uses microorganisms in the presence of oxygen and nutrients to
metabolize toxic organic compounds and converts them to simpler and less toxic products, although some
intermediate products may be more toxic. Often, biodegradation can be applied to a contaminated
medium by the introduction of nutrients (mainly in the form of nitrogen and phosphorus) and oxygen.
Addition of microbial cultures may or may not be necessary depending on whether the native media
contain microbes which can be acclimated to metabolize the contaminants. There is little or no evidence
to indicate that augmentation with cultured microorganisms enhances the natural bioremediation process.
The biological destruction technologies can be broken down into two broad categories, namely, ex-situ
bioremediation and in-situ bioremediation.
Ex-Situ Bioremediation--Ex-situ bioremediation can be performed in various reactor configurations
utilizing liquid slurry or solid phase and can be broken down into the following process types:
• Slurry-phase bioremediation (in slurry reactors)
• Solid-phase bioremediation, including
Land farming
Composting . .
Slurry-phase bioremediation includes the mixing of excavated soil or sludge with water in a
reactor (or series of reactors) to create a slurry, which is agitated mechanically. The process adds
appropriate nutrients and controls the levels of oxygen, pH, and temperature (if necessary). The
degradation of pesticides can be enhanced by treatment with photolytic or photocatalytic processes.
Slurry-phase bioremediation is suitable for high concentrations of organic contaminants in soil and sludge.
However, the presence of heavy metals or pesticides in WG01 can inhibit microbial metabolism. The
concentrations necessary to inhibit microbial activity vary depending on the particular metal(s) present and
should be evaluated on an individual basis.
51
-------
Figure 3-6 is a schematic diagram of slurry-phase biodegradation. If the treated and dewatered
solids contain organic contaminants, they may need further treatment. When these solids are
contaminated with heavy metals, stabilization may be necessary. The process water may also require on-
site treatment prior to discharge. Depending on the waste characteristics, air pollution control measures
(such as adsorption by activated carbon) may be necessary.
. tod
Soil to
FRaolamatlo
Waah Wator to Rocyclo or Furtrtor Treatment
Solid-phase bioremediation is employed to treat excavated soil or sludge biologically without the
addition of water to create a liquid medium for biological growth. Landfarming and composting are two
forms of solid-phase bioremediation which have been used extensively for nonhazardous and hazardous
applications.
In landfarming, contaminated soil is placed in a lined bed to which nutrients such as nitrogen and
phosphorous are added. The bed is usually lined with clay and plastic liners; furnished with irrigation,
drainage, and soil-water monitoring systems; and surrounded by a berm. Aeration, temperature control,
and a leachate collection system may increase efficiency. This process is one of the older and more
widely used technologies for hazardous-waste treatment. It has been successful in the United States,
especially at petroleum refinery (treated under RCRA) and creosote-contaminated sites.
Composting is a variation of solid-phase bioremediation. Waste decomposition occurs at higher
temperatures resulting from the increased biological activity within the bed. The composting process can
treat highly contaminated material by mixing contaminated soil with a bulking agent (wood chips, straw,
bark, manure), piling it, and aerating it (with natural convection or forced air) in a contained system~or by
mechanically turning the pile. When added to compost, bulking agents, improve texture, workability, and
aeration; carbon additives provide a source of metabolic heat. One significant disadvantage of
composting is the increased volume of treated material due to the addition of bulking agents. Simple
irrigation techniques can optimize moisture for biological growth; an enclosed system can achieve volatile
emissions control. Where temperature is critical to removal rates, other sources of organic matter can be
added to the contaminated soils or sludge to increase the biological activity and, therefore, the
temperature of the system.
52
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In-Situ Bioremediation-ln-situ biodegradation promotes and accelerates natural processes in
undisturbed soil. It can use recirculation of extracted groundwater that is supplemented aboveground with
nutrients and oxygen. Alternatively, vacuum or injection methods can supply oxygen to the subsurface soil.
In-situ biodegradation requires proper liquid drainage collection and a recirculation system to ensure proper
contact as well as sufficient aeration to support aerobic bacterial growth.
Under appropriate condition's, this technology can destroy organic contaminants in place without the
high costs of excavation and materials handling. It can also minimize the release of volatile contaminants into
the air. However, in-situ bioremed|ation normally requires time to achieve remediation goals. Figure 3-7
presents a schematic diagram of|an in-situ biodegradation process. Surface treatment of recovered
groundwater may accompany this process.
Nutrient
Adjustment
pH
Adjustment
Metering
Pump
Air
Blower
Air
Injection
Metering
Punp
Infiltration Gallery
Contaminated
Soil
MP-IS7I VIM
Figures-? Schematic lor In-Situ Btoremedtetion Using Injection
for Pesticide-Contaminated Soill.
Applicability-Bioremediation can be applied to treat soil, sludges, and sediments contaminated with
pesticides from waste groups WG02, WG03, and WG04. It can be applied to both in-situ and ex-situ modes
of treatment. ,
Bioremediation is not effective for inorganic pesticides (WG01) containing toxic heavy metals (As, Pb,
etc.). It requires the longest treatment period of the various technologies considered for pesticides; however,
the process has the potential of being the lowest cost alternative, and there are minimal residual management
steps compared to other options. Studies performed using anaerobic degradation indicate that microbial
degradation of DDT is rapid, but the common product of this reaction is ODD, which is resistant to further
anaerobic degradation. Aerobic degradation may cleave the aromatic ring, but thus far aerobic degradation
seems to require low concentrations of pesticide and carefully controlled conditions. In addition, the
degradation rates for DDT are slow [52]. ,
53
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SiaiUS-Bioremediation is an innovative destruction technology suited for the treatment of pesticide-
contaminated soil, sludges, and sediments. The basic technology is available on a full-scale basis. To date,
bioremediation has been selected as the remediation technology in one ROD, for the Leetown Pesticide site.
(See Table A-1 in Appendix A.) Additionally, it was named as part of the cleanup removal action at two non-
NPL sites. (See Table A-2 in Appendix A.) At Koppers Company, Inc. (the Oroville plant) in California, a wood-
preserving site, an in-situ bioremediation system with nutrient addition and oxygen supply is being used to
remediate 110,000 yd3 of soil to a depth of 10 ft [53]. Other ongoing bench- and pilot-scale development works
aim to enhance biodegradation by using various microbes or side stream treatment with UV photolysis and
photocataiysis. The objective of the development studies is to improve the kinetics and degradation conversion
efficiency intrinsic to most of the microbial degradation processes.
Performance—Table 3-23 lists the results from tests in which bioremediation was used to treat
pesticide-contaminated soils.
TABLE 3-23. RESULTS FROM BIOREMEDIATION TESTS WHEN USED
TO TREAT PESTICIDE-CONTAMINATED SOILS
Pesticide
2,4 -D
2,4.5 -T
2,4,6 - triazine
Parathton
Heptachlor
Dieldrln
Initial Concentration
(ppm)
300
-
-
300
1.46
1.44
Final Concentration
(ppm)
30
-
-
30
0.05
0.8
Removal (%)
90
90
90
90
96.6
44.4
Reference
54
—
—
—
55
—
Process Specifics-Microorganisms (principally soil bacteria, actinomycetes, and fungi) make up the
most significant group of organisms involved in bioremediation. Soil, sludge, and sediment environments
contain a diverse naturally occurring microbial population. In general, bioremediation is affected by the pH,
moisture content, oxygen content, and nutrient concentration of the environmental media. Bioremediation can
be performed in either aerobic or anaerobic treatment conditions. Pesticides containing high percentages of
chlorine are more resistant to bioremediation. For example, DDT (WG02) a highly chlorinated pesticide, has
a faiodegradation rate constant of 0.00013 day"1 in soil medium, whereas parathion (WG04), a nonhalogenated
organophosphorus pesticide has a biodegradation rate constant of 0.029 day"1 [52]. This means it would take
over 5,300 days for bacteria to biologically degrade the DDT concentration by 50 percent in soil medium,
whereas parathion would be biologically degraded to 50 percent of its initial concentration in approximately 24
days.
For highly chlorinated pesticides, photolysis or photocataiysis can enhance the kinetics and
effectiveness of biodegradation. Photocatalytic microbial degradation of soils, sludges, and sediments can be
carried out in a recirculating slurry reactor using UV light and a photocatalyst such as titanium dioxide(TiO2).
In powder form TiO2 is mixed with the contaminated media undergoing biodegradation. To date, TiO2
enhancement is experimental.
54
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Addition of nutrients (such as nitrogen and phosphorus) to the contaminant matrix is required for both
in-situ and ex-situ applications to ensure viability of microbiall populations. Following biodegradation, the
photocatalyst, if used, may be recovered, recycled, and reused. The treated media are suitable for
reclamation.
The front-end unit operations for application of ex-situ bioremediation are similar to those required for
catalytic dehalogenation or hydroprocessing. In-situ bioremediation of soils and sediments may require
periodic plowing to ensure adequate contact between the- pesticides and the microorganisms. In-situ
application requires installation of a drainage, dispersion, and recirculation system to supply nutrients and
oxygen to the pesticide-contaminated matrix. ^ ' .
i* - •
Costs-A list of bioremediation treatment cost ranges? js contained in Table 3-24. A 5-acre area with
a thickness of 2 feet was treated by in-situ bioremediation for 3 years, Capital costs were $250,000, and first
year O&M costs were $1,500,000 (1989) [22,30]. In anothercase, the treatment of 50,000 yd3 of material in
a soil slurry bipreactor for 3 years incurred $3,000,000 in capital costs and $581,000 in first year O&M costs
(1989) [24,35]. '.':'..
TABLE 3-24. BIOREMEDIATION COST RANGES
In-Situ Treatment
$50-1 00 per ton
* ", Ex-situ Treatment
$50-200 per ton;
Data Needs-The data needs and possible results relative to each parameter are presented below in
Table 3-25. Other factors that could affect the applicability and performance of this technology include the type
of native microorganisms, the photosensitMy of organisms present in a system, and the degradation constants
of the various components of contaminants.
TABLE 3-25. DATA NEEDS FOR BIOREMEDIATION [17,19,56]
Data Needs
Moisture content
pH
Particle size
Water solubility of contaminant
Oxygen availability
Temperature
Variable waste composition
Possible Effects
May inhibit solid-phase aerobic remediation (land planning) of soils if >80%
saturation. Soil remediation is inhibited if <40% saturation; soil slurry reactions
may have 60-90% moisture content; liquid phase reaction may have >99%
moisture content
pH outside of optimal range (4.5-7.5) reduces process effectiveness
Highly variable particle size may reduce contaminant-microorganism contact,
thus reducina rate of bioremediation
Low solubility can hinder biodeqradation
Determines the rate of microbial growth and sustains aerobic activity (.2 mg/L
dissolved), which inhibits anaerobic activitv (.1%)
Determines process viability and affects biodegradation rate. Inhibits microbial
activity if outside of optimum range of 15-35°c
Causes inconsistent microbial growth. 'Large variations affect biological activity
and result in inconsistent biodegradation rates
55
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TABLE 3-25. (Continued)
Data Needs
Heavy metals, highly chlorinated organics, some
pesticides and inorganic salts
Nutrients (C, N & P)
Biodegradability
Soil permeability
Organic content
Site hydrology and hydrogeology
Possible Effects
Can harm and retard growth of microorganisms
Lack of nutrients affect activity, which results in limited microbial growth
(suggested C/N/P ratio: 120/10/1)
Low biodeqradability inhibits process.
Allows movement of water, air, and nutrients throuah contaminated area
Lack of organics substance can limit biological growth; oil and grease levels
>5% may inhibit microbial activity
Must provide groundwater flow patterns that permit pumping for extraction and
re-injection
SEPARATION/CONCENTRATION OPTIONS
This technology category primarily presents a means of separating contaminant pesticides from soils,
sediments, and sludges, thereby reducing the volume of hazardous waste that must be treated or disposed.
Typically, volume reduction methods include techniques that segregate nonhazardous from hazardous wastes
and are primarily used as a pretreatment step. Separation/concentration technologies are capable of limiting
environmental mobility of pesticide contaminants by separating the toxic components into a controlled phase
for further management; however, no destruction or reduction of toxicity is attained.
By separating and treating the hazardous waste from the matrix, reductions in the treatment volume
and costs may be achieved. Separation/concentration techniques are mass transfer processes that are
necessary to produce isolated or concentrated streams that can be treated by destruction or immobilization
technologies. The separation/concentration technologies for potential remediation of pesticide-contaminated
soils, sludges and sediments can be classified as follows:
• In-situ technologies:
Soil flushing
Soil vapor extraction (SVE)
Steam extraction.
Radio frequency (RF) heating
• Ex-situ technologies (excavated soils):
Soil washing
Thermal desorption
Solvent extraction
The decision to select and implement separation/concentration techniques for remediation of soils,
sludge, and sediments rests primarily on action levels established for the site, acceptable residuals
management, and further need for treatment of concentrated pesticide wastes. Additionally, in-situ
technologies may be used to remediate excavated soil. Additional post-treatment and residuals management
56
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expenses must be considered as part of the overall site remediation and O&M costs. A key issue for the
separation/concentration technologies is the management and dispqsal options for the process extract phase.
Although not discussed in this guide, regulatory compliance artWdisposal criteria for extract phase materials
must be addressed.
In-Situ Separation/Concentration Technologies
Soil Flushing-
Soil flushing is an innovative treatment technology that has been selected at two Superfund sites for
the remediation of pesticide-contaminated materials. It is a physical separation process in which water or some
other aqueous liquid is injected into contaminated soil to extract pesticides or other contaminants dispersed
in environmental media. I'
The system incudes extraction wells in the area of contaminated soil, injection wells upgradient of the
contaminated area, and a wastewater treatment system. Soil flushing must be used in conjunction with an
effective containment/collection system, i.e., slurry walls or other impermeable barriers, in order to prevent
migration of contaminants and extraction fluids to uncontaminated areas of the aquifer [26,57].
In soil, the organic and inorganic contaminants tend to become adsorbed on the clay and silt particles.
The process of soil flushing uses water or aqueous detergent solutions to extract the pesticide contaminants
from the media to a concentrated form. Soil flushing technologies do not destroy the toxicity characteristics
associated with the pesticides and the mobility of pesticides could be increased if in-situ soil flushing is
employed. The soil flushing process uses various additives such as surfactants, acids, chelating agents, etc.,
to increase separation effectiveness. The flush water, which is rich in contaminants, can be treated on or off
site.
Applicability-Soil flushing is suitable for separating and concentrating a wide variety of heavy metals
and organic contaminants. Potentially, these technologies can be applied to separate/concentrate pesticides
from all waste groups (WG01, WG02, WG03, and WG04) dispensed in environmental media including soils,
sludges and sediments, although it is best suited to WG01 contaminants in sandy/gravelly soils: Soil flushing
technologies could be used on piles. Extreme caution must be taken to control the infiltration of flushing
solution and removal of groundwater so as to capture all of the solubilized contaminants. If this is not achieved,
the flushing solution may increase the mobility of the contaminamt in the environment.
Soil flushing is likely to be most effective on permeable soils, such as coarse sand and gravel. The
presence of higher percentages of clay, silt, and humic content can affect soil flushing efficiencies adversely
because of the high degree of pesticide adsorption. In addition, soil with high cation exchange capacity (CEC)
tends to bind some organic and organo-metallic pesticides, which may be very difficult to separate by soil
flushing. ,
Often, hydrophilic organic pesticides (WG03) are separated easily by soil flushing using water alone.
Hydrophobic organic pesticides (WG02) may require the aid of compatible surfactants to flush the compounds
from soils, sludge, or sediment.
Status-Soil flushing is an innovative technology that has had limited application in the United States.
Soil flushing technologies are available for full-scale implementation. To date, soil flushing has been selected
as the remediation technology for pesticide-contaminated soil at two Superfund sites, the Ciba-Giegy
Corporation and Vineland Chemical sites. (See1 Table A-1 in Appendix A.) Contaminants of concern at Ciba-
Giegy were DDT and lindane (WG02), while those at Vineland Chemical were arsenic herbicides (WG01).
57
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Eerforrnance-Soil flushing has been effective for selected pesticides in soil medium.
Process gpecifics-Soil flushing requires an effective collection system to prevent migration of
pesticide contaminants and potential contamination of groundwater. Additionally, in-situ applications require
mobile tanks and pumps to apply the flush water and the additives/chemicals. The liquid flushed out of the
media containing the pesticide contaminants typically requires separation of the contaminants before it can
be recycled and reused. Figure 3-8 shows a schematic of the treatment train for an in-situ application of soil
flushing.
Soil flushing is a time-consuming process because of the numerous diffusional resistances that can
be encountered by the aqueous liquids in making contact with the contaminants. Media containing high
percentages of clay and silt tend to adsorb the organic pesticides, which may be very difficult to separate by
flushing. Bacterial fouling of infiltration and recovery systems may present a problem particularly if high iron
concentrations are present in the groundwater. Flushing additives such as surfactants and chelants may
increase flushing effectiveness but may also pose additional problems for post-treatment requirements for
management of the flush streams.
The major residual stream from flushing is wastewater generated from the process. The wastewater
is expected to contain the pesticide contaminants as well as any additives used to aid flushing. To the extent
possible, this wastewater should be separated from the contaminants and reused. The wastewater treatment
process sludges and solid residuals in the contaminant stream can be sent to a RCRA/TSD facility for disposal
or can be treated on-site.
Figure 3-8 Schematic for Soil Flushing (In-SItu) of Pesticide-Contaminated Soils.
£2SlS-The costs associated with this technology include the installation of the flushing system in the
pretreatment phase and washwater treatment, recycling and disposal of additives, and disposal of the
contaminant in the post-treatment phase. Typical costs for the entire treatment train range from $50 to $120
per ton. Soil flushing treatment of a 1,000 ft2 area (no depth data reported) incurred $4,700,000 in capital
expenditures and $530,000 in first year O&M costs (1989) [24,35].
58
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Data Needs-Implementation of flushing operations requires information on site remediation
objectives, as well as a physical and chemical characterization of the site. Treatability tests should be
performed to determine the effectiveness of a specific soil flushing process and additives. Data needs and
possible effects relative to these parameters are listed below in Table 3-26. Other factors that may influence
the effectiveness of this technology include the solubility and partition coefficients of contaminants in the
presence of surfactants and chelants and the silt, clay, and, humic content of soil. Reference 58 contains a
worksheet for evaluating the feasibility of soil flushing treatment at pesticide-contaminated sites. SVE
technology may also be applicable to sites having significant levels of VOC contamination due to the pressure
of carrier solvents used during the application of pesticides. •
TABLE 3-26. DATA NEEDS FOR SOIL. FLUSHING [19,26,57]
Data Needs
Soil permeability
Soil porosity
pH, buffering capacity
Moisture content
Cation exchange capacity (CEC)
Site hydrogeology
Heavy metals
Number and type of contaminant(s)
Total Organic Carbon (TOG)
Variation in soil composition
Silt, clay, and humic content of soil
Solubility/partition coefficient of contaminants)
in presence of surfactants or chelants
Groundwater hydrogeology
Possible Effects
Affects treatment time and process efficiency; process is most effective in
permeable (K> 1 x 10"3 cm/sec) soils
Determines moisture capacity of soil at saturation
Affects pretreatment requirements; high buffering capacity may increase
reagent requirements. pH may influence solubility of contaminants
Affects flushing fluid transfer requirements; high moisture content decreases
flushing fluid transfer
May affect treatment of metallic compounds; high CEC (>1 00 meg) interferes
with metals removal
Affects flow patterns that permit recovery of flushed contaminants
May require pH adjustment (leaching) for removal
Formulation of suitable Hushing fluids difficult in applications with complex
contaminant mixture
Increasing TOC levels cause increasing contaminant adsorption, resulting in
greater difficulty in removal by flushing
May require frequent reformation of flushing fluid
May cause increased adsorption of contaminants, resulting in greater
difficulty in removal by flushing
Affects selection of flushing fluids for optimum results
Critical in controlling recovery of injected fluids and contaminants
59
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Soil Vapor Extraction (SVE)»
Soil vapor extraction is an innovative in-situ treatmejjygchnplogy that extracts VOCs from the vadose
zone in the contaminated subsurface soils. This technology is known in the industry by various other names
such as vacuum extraction, in-situ volatilization, soil venting, etc.
SVE can be applied in forced and/or suction mode. The forced mode uses hot air or other carrier gas
to force the volatile organic vapors out of the soil toward vent pipes installed into the ground. The suction
mode of operation applies a vacuum to the vents to withdraw the VOC vapors out of the soil. The extracted
VOC vapor can either be condensed and sent off site for further disposal or treated in the vapor phase using
carbon adsorbers or a suitable destruction technology. The noncondensable gases (e.g., air, CO2, etc.)
associated with the extract phase can be vented to the atmosphere after treatment through carbon adsorbers
to remove trace quantities of VOCs.
Applicability-Soil vapor extraction treatment can be effectively applied to soils contaminated with
pesticides having vapor pressures greater than 0.5 mm mercury (Hg). Chemicals with vapor pressures less
than this would not be expected to respond well to SVE treatment. Therefore, SVE may be applicable only
for media contaminated with chlorinated aliphatics (WG03) or other pesticide compounds, such as
thiocarbomates and oxime N-acylcarbomates (WG04), which have relatively high vapor pressures. These
compounds tend to volatilize in ambient air and are diffused in the soil gas. Most other pesticides, including
inorganics (WG02) and halogenated water insoluble organics (WG02), are typically nonvolatile and do not
have sufficient vapor pressure to make the soil vapor extraction process a feasible treatment option for
pesticide remediation. For example, endrin (WG02) has a vapor pressure of 2 x 10'7 mm Hg at 25°c.
Status-This technology is being implemented at the Sand Creek Industrial site in Colorado which has
pesticides and volatile organics contamination (see Table A-1 in Appendix A). Volatile organic compounds
are the target contaminants for the use of SVE technology at this site.
Performance-No specific data are available for this technology's performance on pesticide-
contaminated soils.
Costs-Soil vapor extraction of a 40,000 ft2 area with 30-foot-deep wells incurred $620,000 in capital
expenditures and $130,000 in first year O&M costs (1989) [24,35]. Typical costs for SVE treatment range
from$10to150/ton.
Data Needs-Data needs and possible effects related to these parameters are presented below in
Table 3-27. Reference 4 contains a nomograph for evaluating the feasibility of utilizing SVE treatment at
pesticide-contaminated sites.
60
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TABLE 3-27. DATA NEEDS FOR SOIL VAPOR EXTRACTION [19,59,60]
Data Needs
Vapor pressure
Henry's law constant
Soiltemperature
Water solubility
Soil permeability
Clay, silt, and humic content
Depth to groundwater
Moisture content
Possible Effects
Affects removal efficiencies; high contaminant vapor pressure increases
removal efficiency (should be at least 0.5 mm Hg fo.r removal)
Affects normal effectiveness (should be at least 0.01 for removal)
Affects vapor pressure of contaminant(s); vapor pressure increases greatly
with increasing temperature
High water solubility decreases treatment effectiveness
Permits solvent removal if permeable (gravel, sand); removal efficiency
decreases for low permeability soils (permeability less than 1 0"4 cm/sec)
Reduces soil permeability, decreasing removal efficiency
Process cost increases for soil below water table
Reduces air permeability in soil severely when saturation is greater than 50%
Steam Extraction-
Steam extraction, an innovative treatment technology, is a physical separation process for the removal
of volatile and semivolatile organic compounds dispersed in soils, sediments, and sludges. The steam
extraction process uses thermal energy generated by steam, hot air, infrared elements, or electrical systems
to volatilize and transport the contaminants through media. For highly volatile contaminants, in-situ steam
extraction is preferred to prevent volatilization and dispersion of the contaminants during material handling.
This technology may be limited in terms of achieving higher desorption temperatures required for separating
higher boiling point or vapor pressure organics from the contaminated media. The extracted contaminants
in the vapor phase can be condensed, adsorbed, or destroyed using a suitable technology. The
noncondensable gases associated with the vapor phase can be vented after passing through a 'carbon
adsorber to remove trace quantities of organic contaminants.
Applicability-Steam extraction technologies can be applied to remove volatile and semivolatile
pesticides from soil, sludges, and sediments. This technology is applicable at sites contaminated with
pesticides that are less volatile than those that are treatable using SVE methods [61 [. Potentially, steam or
hot air extraction can strip low boiling point liquid pesticides (boiling point range 100 °F to 300 °F) for pesticides
in the waste groups WG03 and WG04. Some examples are malathion, ethylene dibromide, and chloropicrin,
etc. Steam or hot air extraction is limited in terms of generating higher temperatures (>300 °F) required to strip
higher boiling solid pesticides (e.g. DDT in waste group WG02).
Toxicity is not affected by steam extraction technologies; however, toxic compounds are removed
from environmental media for subsequent treatment or management. The extracted pesticide vapors can be
treated either in the vapor phase or can be condensed and treated in the liquid phase.
Status-Steam extraction technologies are common processes used in the chemical industry.
However, steam extraction has not been selected in a ROD to remediate pesticide-contaminated soils.
61
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• Perforrnanqe-Although the technology has been demonstrated for priority pollutants such as VOCs
and BNAs, data for demonstration of this technology for pesticide-contaminated soil, sludge or sediment are
not currently available.
Process Specifics-Steam extraction normally refers to removal of volatile or semivolatile organic
compounds from their vapor phase, which is in equilibrium with soluble concentrations in their liquid phase.
Steam extraction can generally be achieved by using one of the following two alternative processes:
• A process in which steam is used to enhance stripping of volatile and semivolatile organic
compounds by producing the effect of steam distillation
• A hot air process in which ambient or hot air is used to strip volatile and semivolatile organic
compounds from contaminated soil media
Some modified versions of the technology, e.g., RF heating, have also been shown to be successfully
applied in the in-situ mode of treatment.
Steam extraction can be used as a front-end technology to separate/concentrate the contaminants
into another phase for subsequent treatment. Steam extraction does not destroy the pesticide toxicity;
however, it transfers the contaminants into a phase that can be managed readily. Like other in-situ
technologies, steam extraction is effective for soils containing higher percentages of sahd and gravel.
In-situ steam extraction requires proper containment and vapor collection/condensation systems.
Figure 3-9 is a schematic diagram of an in-situ steam extraction application. Steam extraction generates a
vapor phase rich in pesticide concentration that contains steam which produces an aqueous layer upon
condensation. Depending upon the solubility of the pesticide in water, the aqueous layer may require separate
treatment. The condensed layer of pesticide can be processed using destruction technologies.
Steam
Vent
Wator
Supply -
(Air, Non-Condensables)
Vapor
Phase
Carbon
Adsorber
Light Organic
Liquid Phase to
Further Treatment/
Recovery
Aqueous Phase to
Further Treatment/
Discharge
Heavy Organic Liquid
Phase (if any) to
Further Treatment/
Recovery
WP-4JM 10104
Figure 3-9 Schematic for Steam Extraction (In-Situ) of Contaminated Soils.
62
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Costs-Post-treatment costs for this technology are dependent on the disposal of the contaminant,
air pollution control, off-gas and scrubber water treatment, carbon replacement/regeneration, etc. Typical
treatment costs for this technology train are $100 to $300 per ton for the in-situ mode of treatment [24,25].
Data Needs-Implementation of the steam extraction technology requires complete physical and
chemical characterization of the media and contaminants. Bench- and pilot-scale studies should be performed
before the technology is implemented full scale. Data needs and possible effects related to these parameters
are similar to those contained in Table 3-17. Other factors that may influence this technology's effectiveness
include the boiling point, vapor pressure, adsorptive properties, and water solubility of the contaminants.
Radio Frequency Heating-
Radio frequency (RF) heating is an in-situ soil treatment technology designed to heat large volumes
of contaminated soil rapidly and uniformly. Originally, the technology was developed for the processing and
recovery of petroleum hydrocarbons, but it has been an effective treatment method for soils contaminated with
fuels, polyaromatic hydrocarbons (PAHs), volatiles, chlorinated hydrocarbons, PCBs, and pesticides
[62,63,64].
The process utilizes electromagnetic energy in the frequency range of 2 to 13 megahertz (MHz) to
heat soil as high as 300°C. This results in the removal of organic contaminants through a combination of
vaporization, boiling, and steam stripping. Steam stripping has an additional benefit due to the presence of
soil moisture.
Applicability-Radio frequency heating can be used to remediate soils contaminated with pesticides
that typically volatilize in the temperature range of 80°C to 300°C, such as halogenated volatile aliphatics
(WG03). Other pesticides that have been removed include aldrin (WG02), dieldrin (WG02), endrin (WG02),
and isodrin (WG02). Additionally, experiments have shown that contaminants with high boiling points can be
removed from the soil at much lower temperatures than their actual boiling points [64,65]. For example,
removal of PAH compounds with boiling points up to 400°C was achieved in the temperature range of 200 to
300°C [65]. This technology may have similar applicability to sites contaminated with pesticides that have high
boiling points. ' ' ., ' '
Status—Although previously used in the petroleum industry for oil recovery, only recently has RF
heating been used for the cleanup of hazardous waste sites contaminated with pesticides and other organic
compounds. It is currently in the pilot- and field-scale stage and has been demonstrated at the Rocky
Mountain Arsenal in Colorado [66].
Performance-Table 3-28 contains field demonstration results from a pilot RF heating program
conducted at the Rocky Mountain Arsenal. Initial concentrations are the average of 36 samples at depths of
7 to 17 feet. Final concentrations are the average of soil samples in the 200-250°C, 250-300°C, and >300°C
temperature ranges.
TABLE 3-28. RESULTS OF PILOT TEST PROGRAM AT ROCKY MOUNTAIN ARSENAL [64]
Pesticide
Aldrin
Dieldrin
Endrin
Isodrin
Soil Concentrations (ppm)
Initial
1100
490
630
2000
Final
11
3.2
2.8
33
% Contaminant Removal
99.0
99.3
99.6
98.4
63
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Process Specifics-Radio frequency heating is performed by applying electromagnetic energy in the
radio frequency band to contaminated soil. Electrodes, located in holes drilled in the soil, are used to transmit
the energy from a modified radio transmitter to the soil. The radio frequency used for each remedial application
is selected after characterizing the dielectric properties of the soil matrix and determining the size of the area
to be treated [63].
This process is similar to what occurs in a microwave oven, except that the operating frequency is
different and the size of the area to be heated is much larger. In systems heated using RF, soil temperature
rise occurs as a result of ohmic or dielectric heating mechanisms. Ohmic heating results from ionic
(conduction) current in the soil that is created by the applied electric field. Dielectric heating is due to the
physical distortion and vibration of polar molecules in response to the applied electric field. The RF power level
to be applied in a given remediation application is dependent on the dielectric properties of the soil [63].
Decontamination with RF typically involves two steps that occur concurrently once the average
temperature of the soil rises above 50°C.. These steps are (1) heating the soil and (2) contaminant vaporization
and recovery [64,65].
Initially, the soil is heated as high as 200°C by the electrodes placed in the bored holes. The electrodes
are designed specifically to apply RF power and, at the same time, to collect subsurface vapors and gases
using a vacuum. Fugitive emissions are prevented from escaping by a vapor containment barrier which also
provides thermal insulation to prevent excessive heat loss from the soil near the surface. The system utilizes
horizontally-placed gas collection lines located beneath the vapor barrier in order to capture gases and vapors
at the soil surface [65].
The second step of the process consists of collection, recovery, and on-site treatment of the vapors
and gases. After collection, the gases are transported to an on-site treatment system, which consists of cooling
and dehumidification, followed by treatment with activated carbon, combustion in an afterburner, and/or gas
scrubbing to remove acid gases. The specific gas treatment options selected are dependent on the particular
contaminants present in a given application. Condensed liquids are separated into aqueous and organic
fractions. The aqueous phase is treated using a combination of activated carbon and filtration. The organic
phase is collected and destroyed at an approved treatment facility [64,65].
A complete RF heating system for treatment of contaminated soils requires at least four major
subsystems:
1) An RF energy application electrode array
2) An RF power generation, transmission, monitoring, and control system
3) A vapor barrier/contaminant system
4) Gas and liquid condensate treatment systems [63]
Costs-Costs for RF heating vary between $60 and $180 per ton of soil, depending on the soil moisture
content, the nature of contaminants, the final treatment temperature, and the method used for on-site vapor
treatment [64].
Data Needs-Listed in Table 3-29 are data needs for RF heating.
64
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TABLE 3-29. DATA NEEDS FOR RIF HEATING [64,651
Data Needs
Type of soil
Presence of metal drums or metallic debris
Type of contaminant(s)
Moisture content
Flow rate and depth of groundwater table
Potential Effect
Low permeability soils increase costs and decrease
contaminant recovery; dielectric properties of soil determine
RF power requirement
Disrupts current flow; may interfere with electrode placement
Requires supplementation with other treatment methods if
nonvolatile contaminants (boiling points > 300°C), heavy
metals, or inorganic salts are present
High moisture content increases energy requirements and
impacts removal efficiency of organic contaminants
Presence of fast moving groundwater in heated zone acts as
an energy sink and negatively impacts process cost; may
require diversion of water from heated zone by slurry walls,
etc.
Ex-Situ Separation/Concentration Technologies
Soil Washing-
Soil washing is an innovative treatment technology in which contaminants are removed from soils by
dissolving or suspending them in a wash solution which is treated later by conventional wastewater treatment
or particle size separation methods. Because most organic and inorganic contaminants tend to bind (either
chemically or physically) to clay and silt particles, washing processes that separate the fine particles from
coarser sand and gravel effectively separate and concentrate the contaminants in a smaller volume of soil
which then can be treated by another technology. The silt and clay, in turn, tend to attach to the coarser sand
and gravel particles. The soil washing process separates the contaminants from the clay and silt particles and
suspends or dissolves them in an aqueous medium to facilitate further treatment by another method, such as
biodegradation.
Soil washing is an ex-situ mode of treatment unlike soil flushing, which generally is used in the in-situ
mode. Soil washing is suitable for separating and concentrating a wide variety of heavy metals and organic
contaminants. This process uses various additives such as surfactants, acids, chelating agents, etc., to
increase separation effectiveness. The wash phase, which has a high contaminant concentration, can be
treated. After several passes of washing, the soil may be suitable for reclamation depending on the
effectiveness of the washing agent.
Applicability-Soil washing can be applied to separate/concentrate pesticides from all waste groups
(WG01, WG02, WG03, and WG04) dispersed in environmental media including soils, sludges and sediments.
These technologies can reduce the volume of affected media associated with the contaminants by transferring
them to a concentrate phase.
65
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The presence of higher percentages of clay, silt, and humic content can affect soil washing
efficiencies adversely because of the high degree of pesticide adsorption and large amounts of contaminated
fines that require treatment. Environmental media with high cation exchange capacity (CEC) tend to bind
some organic and organo-metallic pesticides and may be very difficult to separate by soil washing.
Hydrophilic organic pesticides (WG03) are potential candidates for soil washing using water alone.
Hydrophobia organic pesticides (WG02) usually require the aid of compatible surfactants to wash the
compounds from a soil, sludge, or sediment. Surfactants that have used in-soil washing tests include
Witcolate WAC-LA, Tergitol 15-S9, and a 50/50 blend of Adsee 799 and Witcomol NP-100 [67].
Status-Soil washing is an innovative technology that is available for full-scale implementation. To
date, soil washing has been selected as a remediation technology at four Superfund sites (listed in Appendix
A). Table 3-30 contains information regarding these sites.
TABLE 3-30. SOIL WASHING REMEDIATION AT FOUR SUPERFUND SITES
Site
Myers Property
Sand Creek Industries
FMC (Fresno)
Vlneland Chemical
Pesticide
DDT
Heptachlor
Dieldrin
DDT
EDB
Toxaphene
Chlordane
Arsenic herbicides
Region
II
VIII
IX
II
Status
Remedial action phase
Record of decision
Remedial design
Not available
Performance-Trie EPA performed pilot-scale treatability studies at the Sand Creek site, Denver,
Colorado, using the Office of Research and Development's Volume Reduction Unit. The Agency found that
soil washing can reduce dieldrin and heptachlor levels with 90 to 95 percent efficiency in soils larger than 200
mesh using a single wash and rinse stage. Initial concentrations for the two pesticides were in the range of
20 to 80 ppm and 200 to 300 ppm, respectively. Residual contamination after one wash/rinse stage for
dieldrin ranged from 2 to 5 ppm and from 5 to 20 ppm for heptachlor. Additional wash/rinse stages would
continue to reduce the contamination levels.
Bench-scale soil washing tests were performed at the FMC Fresno Superfund site [49]. The tests
showed that contaminant reduction for any particular size fraction (greater than 200 mesh) depends on the
number and type of washes used. For example, a single wash removed about 77 percent of the dieldrin from
the soil, whereas three washes using a surfactant removed 99 percent [68].
Additional bench scale soil washing tests were performed for the same site using a froth flotation type
of soil washing. Treatability data for this type of soil washing indicate that surfactant-assisted washing can
obtain average removal efficiencies for organochloro pesticides (WG02 and WG03) in the range of 80 to 85
percent for a single wash and 92 to 99 percent for a triple wash [68]. Froth flotation of organophosphorus
pesticides (WG04) can be removed by a single wash with efficiencies in the range of 81 to 85 percent [68].
Process Specifics-Hydrophobic organic pesticides (WG02) may require the aid of compatible
surfactants to wash the compounds from a soil, sludge, or sediment. Washing additives such as surfactants
and chelants may increase the technology's effectiveness but may also pose additional requirements for post-
treatment steps for wash stream management. Figure 3-10 is a schematic diagram of soil washing for
pesticide contaminated soils, sediments, and sludges.
66
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Wastewater generated from the technology process is the major residual stream from washing. It is
expected to contain the pesticide contaminants as well as any additives used to aid washing. The pesticide-
containing wastewater requires separation of the contaminants and fine particles before it can be recycled and
reused. The process sludges and solid residuals in the contaminant stream can be sent to a RCRA/TSD
facility for disposal or treated on site using destruction, carbon adsorption, or other treatment technologies.
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Figure 3-10 Schematic for Soil Washing of Pesticide-Contaminated Soils, Sediments, and Sludges.
Costs-The costs for this technology include the excavation, conveying, screening and size reduction
in the pretreatment phase, and washwater treatment or disposal, and the recycling/disposal of surfactants or
chelants in the post-treatment phase. Typical costs for the entire treatment train range from $50 to $200 per
ton.
Data Needs-Data needs and possible effects relative to these parameters are listed below in Table
3-31. Solubility and the partition coefficients of contaminants in the presence of surfactants and chelants are
other factors that may influence the effectiveness of this technology.
TABLE 3-31. DATA NEEDS FOR SOIL WASHING [26,69]
Data Needs
Particle size distribution
Soil type
Complex waste mixtures
Wash solution
Possible Effects
Affects efficiency of removal from wash liquid; particles >2 inches in diameter require
pretreatment for oversized particles; particles <0.063 mm in diameter are difficult to wash
Affects pretreatment and transfer requirements; high clay and silt levels make it difficult to
remove contaminants because of their strong adsorption to the particles
Increases difficulty in formulating suitable washing fluid; solubility of different contaminants
may vary
Presence of surfactants or other reagents in wash solution may cause difficulties in
wastewater and sludge treatment/disposal
67
-------
TABLE 3-31. (Continued)
Data Needs
Particle size distribution
Metal content
Organic content
Partition coefficient
pH, buffering capacity
Possible Effects
Affects efficiency of removal from wash liquid; particles >2 inches in diameter require
pretreatment for oversized particles; particles <0.063 mm in diameter are difficult to wash
Concentrations and species affect selection of wash fluid, mobility of metals, and post-
treatment
Concentration and species affect selection of wash fluid, contaminant mobility and post-
treatment
High coefficient requires excessive volumes of washing fluid since contaminant is highly
bound
Can affect pretreatment requirements, wash fluid selection, and choice of materials of
construction for equipment
Thermal Desorption--
Thermal desorption is an innovative treatment technology that has been selected at three Superfund
sites for the remediation of pesticide-contaminated soils. It is a separation process for the removal of volatile
and semivolatile organic compounds dispersed in an environmental media such as soil, sediment or sludge.
Desorption refers to the removal of low to medium boiling point organic compounds from media surface.
Often, this is accomplished by raising their temperatures to above their boiling points to overcome the surface
adsorption force, followed by removal of organic vapor by a carrier gas. Desorption processes use thermal
energies to volatilize and transport the contaminants to the desorbed phase.
Thermal desorption includes a broad range of processes in which thermal energy (e.g., heated air,
infrared volatilization, laser-induced desorption, etc.) is utilized to desorb semivolatile and low-to-medium
boiling point organic compounds (including those with boiling points of up to 1,000 °F) from contaminated soil
media. The contaminants in vapor phase are either destroyed or treated by carbon adsorbtion.
Applicability-Thermal desorption technologies can be applied to remove semivolatile and low-to-
medium boiling point pesticides from soils, sludges, and sediments. Desorption can be applied to remediate
the aforementioned media contaminated with pesticides from waste groups WG02, WG03, and WG04.
Inorganic pesticides containing volatile metals (WG01) also may be volatilized by thermal desorption [70].
Desorption is generally suitable.for application in the ex-situ mode of treatment. Toxicity is not
affected by the thermal desorption technology; however, toxic compounds are removed from environmental
media for subsequent treatment or management. The desorbed pesticide vapors are either treated in the
vapor phase or can be condensed and treated in the liquid phase.
Status-During a field operation, the Low Temperature Thermal Aeration (LTTA) technology,
developed by Canonie Environmental Services Corporation, successfully treated pesticide-contaminated soils
[71]. During field-scale testing at a U.S. Air Force base site in Florida, thermal desorption technology
successfully removed agent orange containing 2,4-D and 2,4,5-T from contaminated soils [72]. Three
sites—the Ciba-Geigy Corporation in Alabama, Aberdeen Pesticide Dumps in North Carolina, and Arlington
Blending and Packaging Company in Tennessee-are implementing thermal desorption to remediate pesticide-
contaminated soils. (See Table A-1 in Appendix A.)
68
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Performance-Several remedial actions have been conducted using thermal desorption technology.
Two removal actions were conducted to remove atrazine, diazinon, prometryn, and simiazine at the Ciba-Geigy
site. Additional actions were conducted at the Aberdeen (for DDT, toxaphene, benzene hexachloride removal)
and Sand Creek sites. Table 3-32 lists the test results from a thermal desorption study conducted using the
LTTA system for contaminated soil at a western Arizona site.
TABLE 3-32. RESULTS OF LTTA THERMAL DESORPTION STUDY [71]
Pesticide | % Removal
Toxaphene
DDT
ODD
DDE .
Endosulfan I
Dieldrin
Endrin
>99.4->99.9
99.8-99.9
>98.8->99.9
81.9-97.8
>98.8->99.9
>98.6->99.8
>99.6->99.9
Process Specifics-Thermal desorption is used to desorb low-and-medium boiling point liquid organic
pesticides dispersed in environmental media. The operating temperatures for thermal desorption processes
are generally lower (200 to 1,000 °F) than incineration (1,600 to 2,000 °F). Thermal desorption above 1,000
°F is avoided because it leads to severe pyrolysis and the formation of other intermediate toxic products.
Desorption temperatures should be kept as low as possible (preferably in the range of 200 °F to 300 °F);
however, this may not be effective in desorbing medium- to-high boiling point organic pesticides.
Like incineration, thermal desorption requires front-end material handling steps for ex-situ modes of
operation. Soil requires excavation, sludge requires dewatering and, sediment requires dredging. High
percentages of free moisture in the waste require higher energy usage to volatilize the desired contaminants.
However, high percentages of free moisture may also enhance the volatilization of medium boiling point
organic pesticides by producing the effects of steam distillation.
If necessary, the vapors generated from a thermal desorption process can be destroyed/oxidized
further in an afterburner with an extra stoichiometric quantity of air. The afterburners are operated at higher
temperatures (>1,600 °F) and at a fluid residence time sufficient to achieve greater than 99.99 percent
destruction efficiency. The off-gases from the afterburner are cooled, filtered, and scrubbed/neutralized using
air pollution control equipment. Figure 3-11 is a schematic diagram of a treatment train using a desorber/
volatilization unit and afterburner as the primary destruction technology with associated material handling steps
and residual streams.
Thermal desorption technologies have demonstrated high efficiencies for pesticide removal from
contaminated soil media. The overall removal efficiency is highly dependent on the effectiveness of its units
and techniques. The efficiency of thermal desorption is primarily dependent on the bed temperature and
residence time of the medium in the desorber. Selection of appropriate bed temperature is critical when
thermal desorption is applied to a media contaminated with a mixture of pesticides that have a wide range of
boiling points.
For example, a contaminated soil containing four pesticides, e.g., lindane (WG02), malathion (WG04),
chloropicrin (WG03), and zinc-phosphide (WG01), has widely divergent boiling points. The boiling points of
the pesticides at 1 atmospheric pressure are: lindane, 613 °F; malathion, 313 °F; chloropicrin, 234 °F; and zinc-
phosphide, 2,000 °F. The sample soil mixture, when thermally desorbed at 500 °F, volatilizes chloropicrin and
malathion only. If the desorption temperature is raised to 800 °F, lindane can be desorbed along with malathion
and chloropicrin; however, it is not realistic to remove zinc-phosphide by thermal desorption due to its high
boiling point. A temperature differential (AT) of approximately 200 °F higher than the boiling point of a pesticide
is required to achieve complete desorption and overcome the intrinsic heat transfer resistances present in the
medium.
69
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of a pesticide is required to achieve complete desorption and overcome the intrinsic heat transfer resistances
present in the medium.
Thermal desorption units require the contaminated media to contain at least 20 to 30 percent solids
by weight. For treatment of sludges and sediments, this translates to substantial front-end dewatering before
feeding to the desorber. For some thermal desorption units, the total organic loading is limited to 10 percent
of the contaminated media's total weight.
Thermal desorption technologies produce three residual streams. They are:
• Soils, sludges, or sediments stripped of the pesticide contaminants
• Scrubber wastewater from the air pollution control system
• Off-gas emissions from the air pollution control system
The soils, sludges, or sediments may be reclaimed after proper analysis. The scrubber wastewater
can be discharged to a publicly-owned treatment works (POTW) or treated on site. The off-gas may require
air pollution control before it can be vented through a stack.
Vsnt
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Decontaminated Soil
Suitable for Reclamation
Figure 3-11 Schematic lor Therm a I Desorption (Ex-S'rtu) for Pesticide Contaminated Soils, Sediments, and Sludges.
Costs-Excavation, dewatering, dredging, conveying, screening and size reduction are necessary for
the preparation of the soil in the pretreatment phase. Air pollution control and scrubber effluent and ash
disposal are required in the post-treatment phase. Including pre- and post-treatment, typical costs are $250
to $350 per ton for the ex-situ mode of treatment [24,25],
Data Needs-Data needs and possible effects relative to these parameters are listed below in
Table 3-33.
70
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TABLE 3-33. DATA NEEDS FOR THERMAL DESORPTION F16.19.701
Data Needs .-.....--..
Moisture content
Particle size distribution
Total solids content
PH
Contaminant concentrations
Presence of metals or inorganics
Volatile metals
Total chlorine
Vapor pressure
Boiling point
Adsorptive properties of contaminant
Possible Effects
High moisture content >20%) increases energy requirement; dewatering or
pretreatment may be required
Oversize (>1-1 .5 in.) particles may require size reduction or screening;
presence of fine silt or clay may generate fugitive dust loading for air pollution
control equipment
Usually a minimum of 20-30% solids is required
Very high (>1 1 ) or low (<:5) soil pH may result in corrosion of system
components
Total organic bonding is limited to approximately 10%; higher organic
bonding may result in incomplete processing
Are not likely or be treated effectively
May concentrate in off-gas and require additional treatment
May affect volatilization of some metals
Affects removal effectiveness; high contaminant vapor pressure increases
removal efficiency and requires less energy for contaminant removal
Affects process temperature and removal effectiveness; low boiling point
reduces energy requirements for contaminant removal
Affects amount of energy required to desorb contaminant from soil particles
Solvent Extraction-
Solvent extraction, an innovative treatment technology, is a separation process for isolating
contaminants dispersed in environmental media-like soil, sludges, or sediments. These processes use
organic solvents to extract organic contaminants whereas soil washing generally uses water or water-based
solution. Solvent extraction is used rarely for inorganic compounds and metals. It provides volume reduction
by removing contaminants from the soil and concentrating them into an extract phase. This technology,
although not selected for a full-scale pesticide remediation, has the potential to be an effective pesticide
remediation technology.
Solvent extraction processes can be divided into two broad categories: conventional solvent extraction
and supercritical fluid extraction. Conventional solvent extraction uses organic solvents to extract the
contaminants of concern selectively. Several passes are required to extract a contaminant to a desired level.
The solvent can be stripped to separate it from the contaminants, and then condensed, recycled, and reused
to provide further contaminant volume reduction and efficiency.
Supercritical fluid extraction uses a highly compressed gas (such as carbon dioxide) above its critical
temperature to extract contaminants that cannot be extracted by a conventional method. The highly
compressed gaseous fluid provides additional diffusive/solvating power over conventional extraction, which
may be required to extract certain contaminants from interstitial spaces in an environmental media. This
process uses pressure and temperature higher than those in conventional solvent extraction.
Applicability-Potentially, solvent extraction technology can be applied to separate/concentrate
pesticides from waste groups WG02, WG03, and WG04 dispersed in environmental media including soils,
sediments, and sludges.
71
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Status-Solvent extraction is a commonly used technology in chemical processing industries, but its
application for environmental remediation has been limited. To date, no ROD has been issued to remediate
any pesticide-contaminated Superfund site using solvent extraction. This technology is, however, available
for full-scale implementation and is a viable option for pesticide remediation considering the solubility
characteristics of many pesticide compounds.
Performance-ln a bench-scale treatability study, use of the B.E.S.T.™ [a patented solvent extraction
process marketed by Resource Conservation Company (RCC), Bellevue, Washington] solvent extraction
process demonstrated 99 percent removal efficiency for a variety of pesticides in waste groups WG02 and
WG03 as shown in Table 3-34 [73]. This process was tested, at bench scale, to remove pesticides from
contaminated soil at the FMC Fresno Superfund site. The results showed that organochloro pesticides,
including DDT, toxaphene, and chlordane, were extracted in the range of 96 percent (single extraction) to 99
percent (triple extraction) [68]. Organophosphorus (WG04) pesticides also were shown to be removed with
90 percent efficiency [68]. Table 3-34 includes results from the RCC B.E.S.T. bench-scale study. Table 3-34
contains the results of bench-scale tests in which a proprietary solvent extraction process was used to treat
pesticide-contaminated soil.
TABLE 3-34. RCC B.E.S.T. TREATED PESTICIDE-CONTAMINATED SOIL — BENCH SCALE
Analyrte
p,p«-DDT
p,p«-DDE
p,p«-DDD
Endosulfan-l
Endosulfan-II
Endrtn
Dleldrin
Toxaphene
BHC-Beta
BHC-Gamma (Llndane)
Pentachlorophenol
Feedstock (ppm)
500
84
190
250
140
140
37
2,600
<30
<30
150
Product Solids (ppm)
0.2
0.5
0.05
<0.02
<0.02
0.02
<0.02
0.9
<0.13
<0.07
1.9
Removal Efficiency (%)
99.96
99.4
99.97
>99.99
99.99
99.99
<99.95
99.97
98.7
TABLE 3-35. RESULTS FROM SOLVENT EXTRACTION TESTS
I Pesticide
Chlordane
DDE
Removal %
>99
>99
Reference
53
—
Process Specifics-Solvent extraction is not a stand-alone technology; however, it can be used as
a front-end technology to extract/concentrate the pesticide contaminants into a small volume for further
treatment. Solvent extraction processes do not destroy the toxicity and hazard associated with the
pesticide contaminants. The affected media, however, can be decontaminated for return to site while the
contaminants are reduced to a small volume for further treatment or disposal.
72
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Solvent selection for extraction plays a key role in achieving high efficiency. The solvent used to
extract a particular pesticide contaminant must be selective, nonreactive, and noninterfering with the other
constituents present in the media. For example, soils contaminated with lindane (WG02) and extracted with
ethanol (solubility: 6.4 gms of lindane/100 gms of ethanol) are significantly less selective and effective per
pass of extraction than an extraction with acetone (solubility: 43.5 gms of lindane/100 gms of acetone).
Normally, in-situ solvent extraction is considered inappropriate because of the potential for pesticide
contaminants and solvents to migrate into the groundwater. Ex-situ applications require front-end material
handling steps to prepare and feed the materials to the extractors. For sludges or sediments, dewatering of
the contaminated media is necessary to provide increased solvent/contaminant contact potential. Figure 3-12
is a schematic diagram of the treatment train for an ex-situ-extraction process using a continuous
countercurrent extractor along with the pre- and post-treatment remediation steps.
Solvent extraction has been effective for several pesticides in the soil medium. Although data are
relatively scarce, it is expected that pesticide-containing sludges and sediments can be extracted using
selective solvents after an initial dewatering step.
The performance of solvent extraction can be affected negatively by the presence of detergents and
emulsifiers in the contaminated media. Water-soluble detergents may dissolve and retain organic pollutants
and prevent transfer to the extraction solvent. Traces of organic solvent present in the treated media may
volatilize and create air pollution hazards. Some of the solvefits required for pesticide extraction may be
flammable and toxic; therefore, residual solvent in the soil may jip hazardous and toxic. Proper precautions
against health and safety hazards must be exercised when handling those solvents.
Solvent extraction generates an extract, a wash stream, and a raffinate phase consisting of the
remediated medium. The extract phase, rich in pesticide concentration, can be processed further using
destruction, adsorption, or other treatment. The raffinate phase (treated soil/sludge/sediment) may be
returned to the site for reclamation if analytical results indicate that remedial goals have been achieved. The
washwater may need to undergo further on-site treatment prior to discharge to a POTW or be sent to an
RCRA/TSD facility for final disposal.
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Contaminated Soils, Sediments, and Sludges.
73
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fiOSlS-Pretreatment costs for this technology include the excavation, dewatering, dredging and
conveying the soil. The post-treatment costs include treatment and disposal of the concentrated contaminants
and wash water. Typical costs associated with solvent extraction are $100 to $400 per ton (1991 $).
Data Needs-Like soil flushing, implementation of solvent extraction requires complete physical and
chemical characterization of the media and contaminants. Treatability tests should be conducted to
determine which solvent or combination thereof is best suited for a particular application. Additionally, tests
should determine whether mass transfer or equilibrium is a controlling factor in the process [74]. Data needs
and possible effects relative to these parameters are listed below in Table 3-36.
TABLE 3-36. DATA NEEDS FOR SOLVENT EXTRACTION [741
Data Needs
Complexity of waste mixture
Particle size
PH
Contaminant size
Temperature
Metals
Organically bound metals
Detergents/emulsifiers
Soil permeability
Solvent characteristics
>
Affects solvent selection
Oversize particles (>2 in.) may require size reduction prelreatment
Must be in a range compatible with extracting solvent
Affects solvent selection and process efficiency; solvent extraction is least
effective for very high molecular weiqht and verv hvdroDhilic oraanics
May impact solubility of contaminants in extraction solvent-this affects
extraction efficiency
Strong reaction may occur during treatment process because of caustic
additions
May be extracted along with organic pollutants and cause disposal/recycling
difficulties
May retain organic contaminants and reduce effectiveness of process; may
cause foaming, which hinders settling and separation characteristics
Affects solvent-contaminant contact; low permeability soils may require
additional contact time for effective treatment
TREATMENT TECHNOLOGY OPTIONS FOR CONTAMINATED GROUNDWATER
EPA's Office of Drinking Water (ODW) and Office of Pesticide Programs (OPP) conducted a survey
[75] in 1990 to determine the nature and extent of pesticide contamination in drinking water wells within the
U.S. The study's objective was to establish a relationship between the use/presence of pesticides and the
contamination of water. The results of the survey (which included 127 analytes) showed that although there
is no widespread health problem linked with pesticides in drinking water, a sufficient number of wells,
especially those from rural areas, showed high levels of pesticide contamination.
There are approximately 94,600 community water system (CWS) wells and 10,500,000 rural domestic
wells in the U. S. Of these, about 10.4 percent of CWS wells (9,850) and 4.2 percent of the rural community
wells (441,000) are contaminated above acceptable limits [75]. After analyzing the results, EPA determined
that there is a need for continued attention and further analysis of the problem posed by pesticide-
contaminated water [76]. To address this concern, various technologies related to pesticide remediation were
evaluated. These technologies are classified in two major categories: destruction technologies and
separation/concentration technologies.
74
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Table 3-37 presents typical treatment combinations for the remediation of pesticide-contaminated
water. It includes pre- and post-treatment requirements, mode of applicafiori, and the status of the particular
technology. The relationship between the applicable media and the pesticide waste groups to the treatment
train processes are given as well.
TABLE 3-37. TYPICAL TREATMENT COMBINATIONS AND TRAINS FOR
PESTICIDE-CONTAMINATED WATER
Technology
Carbon adsorption
Bioremediation
Filtration
Chemical reduction
Chemical oxidation
Hydrolysis /
Neutralization
Evaporation
Ion exchange
Pretreatment/
Materials Handling
Pumping, filtration
Pumping, air injection,
recirculation
Pumping, precoat
handling
Pumping, filtration
Pumping, filtration
Pumping, filtration,
Acid/Base handling
Pumping, filtration
Pumping, filtration
Post-Treatment •
Residual Management
Disposal or regeneration
of spent adsorbents
Gas collection, sludge
disposal, microbes
recycle
Regeneration of filter
bed, disposal of precoat
and filter cake
Catalyst recovery,
disposal of spent
cartridges
Disposal of spent filter
cartridges and spent
catalysts
Collection and disposal
of washwater
Treatment of concentrate
Disposal or regeneration
of exchange resins
Applicability for
Waste Group/Mode
WG01, WG02, WG03,
WG04/Ex-situ
WG02, WG03,
WG04/ln-situ
WG01,WG02,WG03,
WG04/Ex-situ
WG02, WG03,
WG04/Ex-situ
WG02, WG03,
WG04/Ex-situ
WG03, WG04/ln-situ
and ex-situ
WG01.WG02, WG03,
WG04/Ex-situ
WG01 /Ex-situ
Status
Three
pesticide sites
Full scale
One pesticide
site
Full scale
Full scale
Bench scale
Bench scale
Bench scale
Bench scale.
Full scale
Destruction Technologies
Available technologies for destruction of pesticides in water can be further divided into two major
groups: chemical destruction technologies and biological destruction technologies. Chemical destruction
technologies include oxidation, reduction, and hydrolysis/neutralization.
Chemical Oxidation-
Chemical oxidation can be applied to the contaminated water by a photochemical process where
peroxide or ozone and UV light are used to degrade the organic contaminants.
Applicability-Chemical oxidation can be used to treat contaminated water containing low levels of
pesticides from waste groups WG02, WG03, and WG04. Chemical oxidation can be enhanced by the use of
photolysis or photocatalysis. Photolytic or photocatalytic chemical oxidation can be applied only for ex-situ
modes of treatment. Chemical oxidation provides a reduction of toxicity, mobility, and volume of contaminants.
75
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SlatUS-Various versions of chemical oxidation technology have been demonstrated to treat
wastewater containing VOCs and chlorinated BNAs (e.g., chlorophenol and PCP). To date, chemical
oxidation has not been chosen as a treatment in any ROD.
Performanqe-Table 3-38 contains the results of chemical oxidation studies conducted using pesticide-
contaminated water.
TABLE 3-38. RESULTS OF CHEMICAL OXIDATION TREATMENT
Oxidation Technoloqy
Ozone
Ozone
Ozone
Wet
Air
Pesticide
Lindane
Aldrin
Dieldrin
PCP
Triazine
Dinoseb
Carbamic acid
Removal %
75
100
100
•100
•100
95
80
RofcrGncGS
77
78
79
80
Process Specifics-Chemical oxidation reactions can be controlled and are well suited for aqueous
waste streams containing low organic concentrations. Available oxidizing agents include sodium or calcium
hypochlorite, chlorine, ozone, potassium permanganate, and hydrogen peroxide. Pesticide oxidation reactions
occur at ambient conditions; however, these reactions commonly are enhanced by higher temperatures,
catalysts, and UV light. Full-scale application of chemical oxidation technology requires tanks, pumps, and
pipings to apply the oxidants to the contaminated water. Figure 3-13 is a schematic diagram of a typical
treatment train.
Catalyst
Tank
Prefilter
(Optional)
Groundwater ,,„,
Extraction V|^
Wells Zo
ase
ne
I
t_
Met:
Pu
Conveying
& Screening
Equipment
. •
Metering
Pump
Pump
Treated Water
to Discharge
or Recharge
WP-1578 &OW
Figure 3-13 Schematic for Chemical Oxidation of Pesticide-Contaminated Groundwater.
76
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Cosls-Pretreatment costs associated with oxidation include pumping and filtration costs. Post-
treatment costs include the disposal of spent filter cartridges and spent catalysts. Total estimated oxidation
costs for treating pesticide-contaminated water range from $0.20-$0.50 per gallon (1985) [81].
Photolytic/catalytic chemical oxidation of VOC-contaminated groundwater costs $5.35 per 1,000 gallons for
capital costs, O&M is $41,000 a year, and electric power costs $19,480 (1988) [24,82].
Data Needs-Significant parameters that may limit the effectiveness of this technology are listed in
Table 3-39.
TABLE 3-39. DATA NEEDS FOR CHEMICAL OXIDATION [26,83]
Data Needs
PH
Oxidation potential
Temperature
Oil and grease content
High contaminant concentrations
Type of catalyst
Contact time
Optimum treatment conditions
Possible Effects
Suboptimai pH may inhibit chemical reaction and result in a
need for additional treatment contact time
Affects the driving force and rate of chemical oxidation
reaction(s)
Reaction rate may be negatively affected in cold weather; as
temperature increases, so does chemical reaction rate
Presence of oil and grease may increase oxidant demand
since oxidation is nonselective
Highly contaminated wastewater requires large amounts of
oxidant and increases treatment costs
If applicable, presence of catalyst may increase oxidation rate
Must be sufficient to allow maximum effectiveness of oxidant(s)
used
Affects efficiency and treatment process costs; Optimum
treatment conditions vary depending on oxidant used and
contaminants present
Chemical Reduction-
The chemical reduction process uses a reducing agent to lower a compound's oxidation state.
Chlorinated organic compounds in waste groups WG02 and WG03 can be treated to remove chlorine from
the compounds by hydrodechlorination. Chemical reduction by hydroprocessing using molecular hydrogen
can be applied only in ex-situ mode of treatment.
Applicability-Chemical reduction such as hydrodechlorination can be applied to treat groundwater
contaminated with pesticides from waste groups WG02, WG03, and WG04. The technology is applicable
mainly to ex-situ modes of treatment for contaminated water.
Status-Chemical reduction has not been tested thoroughly enough for it to be used to treat pesticide-
contaminated water. However, the technology has been tested for the treatment of pesticide-contaminated
soil. To date, chemical reduction has not been chosen as a treatment for groundwater in any ROD.
77
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Eerformaoeg-Currently, no performance data are'available regarding the use of chemical reduction
processes for treatment of groundwater contaminated with chlorinated pesticides. It is uncertain whether
reduction methods can achieve acceptable reduction of toxicity, mobility, and volume.
Process Specifics-Full-scale application of chemical reduction technologies require pumps, tanks,
and pipings to add the chemicals to the contaminated water. Figure 3-14 is a schematic diagram of a typical
treatment train. Chemical reduction technologies are not expected to degrade the aromatic ring structure
associated with the pesticides which could retain toxicity after treatment. Justification for use of this
technology to treat pesticide-contaminated water depends on factors such as type and concentration of
contaminants, site access and locations, and treatment goals and objectives.
Prefilter „
(Optional)
Groundwalar ,,_,
Extraction vl°
Wells *°
ose
ne
t_
Mete
Pu
Conveying
& Screening
Equipment
<
Recovered
Catalyst
for Reuse
DF^q—r?—»
Filter £=•!
Filter
Feed Pump
Treated Water
to Discharge
or Recharge
Figure 3-14 Schematic for Chemical Reduction of Pesticide-Contaminated Groundwater.
jQosJs-Pretreatment costs include those associated with pumping and filtration. Post-treatment costs
include catalyst recovery and disposal of spent cartridges. Total estimated reduction costs for reduction
processes range from $0.20 to $0.50 per gallon (1985) [81].
Data Needs-Table 3-40 lists the data needs and possible effects of chemical reduction for treating
contaminated groundwater.
78
-------
TABLE 3-40. DATA NEEDS FOR CHEMICAL REDUCTION [26,83]
Data Needs
Reduction potential
PH
Oxidation reduction potential
Temperature
Oil and grease content
High contaminant concentrations
Type of catalyst
Contact time
Optimum treatment conditions
Possible Effects
Affects the driving force and rate of chemical reduction reaction
Suboptimal pH may inhibit chemical reaction and result in a
need for additional treatment contact time •
Affects the driving force and rate of chemical reduction
reaction(s)
Reaction rate may be negatively affected in cold weather; as
temperature increases, so does chemical reaction rate
Presence of oil and grease may increase oxidant demand since
reduction is nonselective
Highly contaminated wastewater requires large amounts of
reducing agent and increases treatment costs
If applicable, presence of catalyst may increase reduction rate
Must be sufficient to allow maximum effectiveness of reducing
agent(s) used
Affects efficiency and treatment process costs; Optimum
treatment conditions vary depending on oxidant used and
contaminants present
Hydrolysis/Neutralization-
Hydrolysis/neutralization is a chemical treatment process that uses an acidic or alkaline solution to
partially decompose and neutralize organic and inorganic contaminants. Heat and a catalyst can enhance
hydrolysis/neutralization reactions. Incomplete or improper hydrolysis of contaminants may produce by-
products that are more toxic than the initial contaminants. Ex-situ hydrolysis can be performed in a reactor
configuration. Hydrolysis/neutralization treatments generally do not require extensive air pollution control
equipment.
Applicabitity-Hydrolysis/neutralization is a method applicable to organophosphorus and carbamate
pesticides belonging to the waste groups WG03 and WG04. The technology can be applied for both in-situ
and ex-situ modes of treatment.
Stalys—Hydrolysis/neutralization has not been tested thoroughly enough for treating pesticide-
contaminated water. However, the technology has been used to degrade pesticides in soil. To date, no ROD
has been issued for the remediation of pesticide-contaminated water using this technology.
Performance--ln a bench-scale study of organophosphorus pesticides, 100 percent efficiency was
achieved in converting a variety of pesticides [84]. Those treated include phorate, trichlorform, and carbamic
acid. In an in-situ treatment of parathion in a site near Phoenix, Arizona, alkaline hydrolysis was carried out
to degrade ethyl/methyl parathion. Concentration of ethyl parathion was decreased by more than 50 percent
and 76 percent after 15 and 69 days, respectively. Concentration of methyl parathion decreased by 81 percent
and 98 percent after 15 and 69 days, respectively [85]. The effect of hydrolysis on carbamate pesticides
yielded 100 percent conversion in a bench scale study, where 31 organophosphate and 5 carbamate
pesticides were treated [86].
Process Specifics-Full-scale implementation of this technology to treat water requires pumps, tanks,
and pilings to add the chemicals to the contaminated water. Figure 3-15 is a schematic diagram of a typical
treatment train.
79
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Generally, hydrolysis of pesticides is affected by pH and temperature. Caution must be exercised
when performing hydrolysis to prevent formation of toxic byproducts. The treatment conditions must be
evaluated through bench- and/or pilot-scale treatability studies. Reaction products and byproducts must be
identified and analyzed fortoxicity. Normally, hydrolysis of pesticide-contaminated water does not require air
pollution control equipment.
:3%2#%2%2^^
t4P»te?< a/am*
Figure 3-15 Schematic for Hydrolysis/Neutralization (In-Situ) of Pesticide-Contaminated Groundwater.
C_Qsls--Pretreatment costs include those associated with pumping, filtration, and acid/base handling.
Post-treatment costs include the collection and disposal of washwater. Total estimated
hydrolysis/neutralization expenditures can range from $0.15 to $0.40 per gallon (1985) [81].
Data Needs-Table 3-41 lists the parameters that may influence the effectiveness of this technology.
TABLE 3-41. DATA NEEDS FOR HYDROLYSIS/NEUTRALIZATION [26.83]
Data Needs
pH
Temperature
Type of catalyst
Reaction products and byproducts
Optimum treatment conditions
Possible Effects
Suboptima! pH may inhibit chemical reaction and result in a
need for additional treatment contact time
Reaction rate may be negatively affected in cold weather; as
temperature increases, so does chemical reaction rate
If applicable, presence of catalyst may increase reduction rate
May require additional treatment if toxic
Affects efficiency and treatment process costs; Optimum
treatment conditions vary depending on reducing agent used
and contaminants present
80
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Bioremediation-
Bioremediation is a destruction process .for treatment of water contaminated with toxic organics. It
uses microorganisms in the presence of oxygen and nutrients to metabolize toxic organic compounds and
convert them to less toxic products. Bioremediation is used mainly to degrade the biodegradable organic
substances in wastewater. The organic wastes are converted into carbon dioxide and biological cells, which
can be removed by settling. The need for nutrients is important for the metabolism of the microbial population.
If necessary, bioremediation can be enhanced by pretreatment with UV radiation (photolysis) or a photocatalyst
(TiO2) during the UV photolysis. Ex-situ bioremediation can be performed in various reactor configurations
utilizing suspended solids or fixed median form.
Applicability--Bioremediation can be applied to treat grouindwater and surface water contaminated with
low levels of pesticides belonging to waste groups WG02, WG03, and WG04. The degradation process can
be applied to both in-situ and ex-situ modes of treatment. Bioremediation can provide reduction of the mobility,
toxicity, and volume associated with the aqueous-phase pesticides.
Status--The Ciba-Geigy Corporation site (see Table A-1 in Appendix A) implemented bioremediation
to treat pesticide-contaminated groundwater. Bioremediation has been effective in aerobic lagoons for pilot-
scale studies. Activated sludge processes have been a convenient way to remediate pesticides in water in
bench-scale, pilot-scale, and full-scale studies. Trickling biological filters have been used on a full scale to
remediate pesticide contamination in water.
Performance-Aerobic lagoons have removed greater than 80 percent of Hndane [87] and 98 percent
of PCP [88]. In a bench-scale study, the wastewater from the manufacture of carbaryl was treated in an
activated sludge process which resulted in nearly 100 percent removal of carbamic acid [89]. Several bench-
scale continuous-flow activated sludge process studies were conducted, and 100 percent PCP removal was
achieved [90]. Pursuant to Section 3004(M) of RCRA, EPA is establishing treatment standards based on BOAT
for organophosphorus wastes.
Under this program, the pesticide parathion was treated at 99.94 percent efficiency in a full-scale
bioremediation experiment [91]. In another full-scale activated sludge study, six Dutch municipal treatment
plants were monitored and the treatment efficiencies of two pesticides, cyclohexane and lindane, showed 78
percent and 88 percent removal, respectively [92].
Process Specifics-Wastewater contaminated with pesticides can be treated by aerobic methods. The
wastewater flows into an aeration basin where a mixed liquor of suspended microbial organisms degrades the
waste while producing new cells. The new cells settle in a clarifier in the form of sludge, a part of which is
recycled in the aeration basin to maintain a steady microbial population.
Application of biotechnology for degradation of pesticides-contaminated water can be both aerobic and
anaerobic. Aerobic types of treatment include activated sludges, aerated lagoons, trickling filters, and rotating
biological contractors. Anaerobic types include anaerobic suspended growth, fixed- film filters, and fluidized
beds.
Acclimation of the bacteria is a key factor in the decomposition of the organic pesticide material in the
wastewater; proper conditions should be maintained so that the growth rate of the bacteria is not affected.
Other features that could affect the bioremediation of pesticides negatively include the presence of toxic heavy
metals, elevated concentrations of halogenated compounds, lack of nutrients, acidic or alkaline pH conditions,
and extreme temperatures. Figure 3-16 is a schematic diagram of bioremediation for treatment of
contaminated water.
81
-------
Nulrlenl
Adjustment
pH
AdjuslmeiK
LS~£
Air
Blower
Election
Wei
To Recharge
Conlamlnaled
Groundwalar
To Further
^ Treatment
or Discharge
Graundwaler
Exlracta
Wells
Vadose
Zone
Submersible
Saturated
Zone
Figure 3-16 Schematic for Bfofemedtetlon (In-SRu) of Pesticide-Contaminated Groundwater.
£QSl§-The pretreatment costs for bioremediation include those associated with pumping, air injection
and recirculation. The post-treatment costs include those incurred by emission control sludge disposal and
microbe recycle systems. The estimated costs for an activated sludge process system are approximately $6.0
million (1985) for a plant size of one million gallons per day (mgd) [81].
Date Needs-The data needs and possible effects relative to these parameters are presented below
in Table 3-42. Other factors that may influence the effectiveness of this technology include the specific type
of bacteria and the solubility and degradation rates of contaminants.
TABLE 3-42. DATA NEEDS FOR BIOREMEDIATION [93]
Data Needs
Temperature
Variable waste composition
Heavy metals, highly chlorinated organlcs, some
pesticides, herbicides
Water and air emissions
Nutrients (C, N, P)
Blodegradabllity
Microbial population
Oxygen
PH
Possible Effects
Optimum temperature range is 15-35 °C; less microbial activity outside
optimum range
May result in inconsistent biodegradation cause by variation in
biological activity
Can be highly toxic to microorganisms.
May have environmental and/or health impacts and require
monitoring/treatment
Lack of adequate nutrients may inhibit biological activity
Low destruction rate inhibits process
Insufficient population may result in low biodegradation rate; bacterial
population may not be able to biodegrade contaminant(s) completely
Lack of oxygen inhibits aerobic processes; presence of oxygen inhibits
anaerobic processes
May inhibit microbial activity if outside the optimum pH range of 4 5-8 8
82
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Separation/Concentration Technologies
Adsorption-
In adsorption, contaminants are adsorbed onto a high surface area adsorbent material [such as
granular activated carbon (GAG)] and transferred and concentrated on the adsorbent. Adsorption can be
used effectively to separate various contaminants from aqueous streams and is widely used to remediate
contaminated water.
Applicability-Adsorption techniques can be used to remediate both surface water and groundwater
contaminated with pesticides belonging to waste groups WG02, WG03, and WG04, and some from WG01
are expected to be removed. Adsorption by GAG is an effective way to remediate organics of low solubility
such as pesticides from aqueous phase. This process normally is performed in an ex-situ mode of operation.
Status-Adsorption of organics from aqueous waste streams is a widely used technology in chemical
and allied industries. Adsorption systems are available for full-scale implementation. To date, carbon
adsorption technology has been selected to treat contaminated groundwater at three Superfund sites. (See
Tables A-1 and A-2 in Appendix A.)
Performance-Adsorption by GAG is a cost-effective method of removing pesticides from
contaminated groundwater. Most of the agrichemicals, which included atrazine, alachlor, cyanazine,
carbofuran, linuron, etc., were removed with an efficiency of more than 80 percent [79]. In another bench-
scale application, washwater from pesticides applicators were treated with adsorption techniques, and 90
percent of the pesticides isopropyl carbanilate and triazine, etc., were removed [94]. A full-scale study on a
GAG treatment system was effective for a small generator with a removal efficiency of 90 percent for
isopropoxylphenyl methylcarbamate and dichlorophenoxyacetic acid [95].
V
Process Specifics-GAC or powder activated carbon (PAG) is used typically for adsorption of
pesticides from affected water flowing through columns or beds. Adsorption is a widely used and reliable
technique for removal of water soluble pesticides. Generally, the affinity for adsorption is greatest for aromatic
organochloro pesticides, followed by cyclical carbon compounds, organophosphorus material, carbamates,
and aliphatics. Inorganic and organometallic pesticides are least adsorbed by GAG or PAG. Effectiveness
of adsorption depends on the strength of the molecular attraction between the adsorbent and the adsorbate,
the molecular weight of the adsorbate, contact time, type of adsorbent, pH, and the available surface area.
Full-scale implementation of adsorption technologies require pumps, pipings, and tanks as depicted
in Figure 3-17. Depending on the paniculate loading of the contaminated water, a prefiltration step may be
required before feeding the water to the adsorber. Adsorption systems most often do not require any air
pollution control equipment. The carbon bed can be regenerated thermally and reused once it has been
saturated with the pesticides.
83
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Contaminated
Groundwater
Groundwater
Extraction
Wells
Submersible
"MWXfXIC&iW,
Vadose
Zone
Saturated
Zone
'•ff^^^S^^
Carbon
Adsorbers
Treated Water
to Discharge
or Recharge
Figure 3-17 Schematic for Carbon Adsorption of Pesticide-Contaminated Groundwater.
C_Q£ii--Pretreatment costs for adsorption include pumping and filtration; post-treatment costs are
based on the disposal and/or regeneration of spent adsorbents. Typical adsorption costs range from $0.10
to $0.40/gallon (1985) [81]. The estimated costs include system purchase or rental, carbon, transportation,
and labor to erect systems and other equipment.
Use of GAG adsorption for treatment of groundwater contaminated with chlorinated volatile organics
incurred $230,000 in capital costs and $82,000 in first year O&M. The system pumped 50 gpm and consumed
31,068 pounds per year of carbon (1989) [24,35]. Another site, which employed an air stripper and carbon
adsorption groundwater treatment system, incurred $366,700 in capital costs and $157,734 in annual
operating costs (1986). The system had a flow rate of 1 mgd [24,96]..
Data Needs-The data needs and possible effects associated with these parameters are presented
below in Table 3-43.
TABLE 3-43. DATA NEEDS FOR ADSORPTION [971
Data Needs
Molecular weight
Polarity
Suspended solids
Otl and grease
Biological organisms
Humlc and fulvic adds
Possible Effects
Low molecular weight compounds are removed with less efficiency
High polarity compounds are removed with less efficiency
Levels >50 mq/L may foul carbon
Levels of >1 0 mg/L may foul carbon
May foul carbon
May cause interference in adsorption of targeted organic contaminants;
may cause carbon exhaustion
84
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Filtration--
Filtration is an ex-situ separation process in which solic|pj^rticle,s are isolated from a fluid stream using
a porous medium. The driving force in the filtration process is1:he gravitational force or pressure differential
across the filtration medium. Filtration techniques include the application of pressure or gravity differential
across the granular or porus media as a means of separating the solids from the fluid. Filtration can be used
to separate various contaminant particulates from an aqueous stream.
Applicability-Filtration techniques can be used to separate pesticide-contaminated water in particulate
form belonging to all four waste groups, but they are not applicable for pesticides which are soluble. Filtration
is applicable for ex-situ modes of treatment only.
Status-Filtration is a commonly used unit operation technique for environmental remediation. There
are numerous versions of filtration systems and techniques available for full-scale use. To date, no ROD has
been issued in which filtration is the selected technology to remediate pesticide-contaminated groundwater.
Performance-ln a bench-scale study, PCPs were reduced by 72 percent in the wastewater generated
from an animal pharmaceutical plant [98].
Process Specifics-Full-scale implementation of filtration technologies requires tanks, pumps, and
pipings to force the contaminated water through the filter unit. Figure 3-18 is a schematic diagram of a
groundwater treatment train using precoat filtration.
Spray
Water
Contaminated
Groundwater
Holding
Tank
Filter Feed
Pump
Groundwater
Extraction
Wells
Submersible
./- Pump
Vadose
Zone
Saturated
Zone
Slurry
Pump
•i
_IA
Precoat
Filter
Spent
Precoat
Material
to Disposal
Treated Water
to Discharge
or Recharge
j<^%^%%%%^^
94P-15B1 8/2/94
Figure 3-18 Schematic for Filtration of Pesticide-Contaminated Groundwater.
QQSJs-Pretreatment costs include those associated with pumping, filtration, and precoat (a disposable
layer of very fine material, such as diatomaceous earth, that acts as a prefilter) handling. Post-treatment costs
include the regeneration of the filter bed and the disposal of the precoat. Total filtration costs can be in the
range of $0.10 to $0.25 per gallon (1985) [81]. A filtration unit with a flow rate of 500 gpm incurred $1,100,000
in capital costs and $110,000 in first year O&M costs (1989) [24,35].
85
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Data Needs-Implementation of appropriate filtration technologies to treat contaminated water requires
characterization of the influent streams for suspended solids content and particle size distribution. Bench-
and/or pilot-scale treatability studies are useful in developing design parameters. The data needs for this
technology and their possible effects are listed in Table 3-44.
TABLE 3-44. DATA NEEDS FOR FILTRATION
Data Needs
Row rate
Resistance of filtration
Temperature
Viscosity
Oil and grease content
Particle size
Possible Effects
Affects sizing and media selection of filtration unit
Affects filtration rate, which directly impacts overall filter
performance; rapid sand filters typically are operated at 2
gpm/ft2
May affect solubility of contaminants in waste stream and
result in seasonal variation in filter performance
Affects filtration rate; are removed with less efficiency; lower
viscosity liquids will pass through a filter faster than higher
ones
May reduce filter effectiveness by causing filter blinding
Filter media particle size affects filtration quality and filtration
rate; as particle size decreases, filtrate quality generally
increases while filtration rate decreases
Ion Exchange-
Ion exchange is a separation process in which cations (or anions) in the aqueous phase are
exchanged with others that are attached to the exchange resins. Normally, ion exchange materials are
synthetic resins made from organic materials that contain ionic functional groups to which exchangeable ions
are attached. Apart from synthetic organic resins, there are other inorganic and natural polymeric materials
that can be used as an ion-exchange material to remove trace quantities of ionic contaminants from aqueous
streams. After the resins have been used to remove certain selected undesirable ions, they can be wasted
or regenerated for reuse.
Applicability-Ion exchange technologies are applicable mainly for inorganic pesticides of waste group
WG01 containing heavy metal cations like lead, cadmium, arsenic, chromium, etc. Pesticides from waste
groups WG02, WG03, and WG04 are generally nonionic and cannot be separated by ion exchange.
£iiiU£--lon exchange is a well established separation technology that is available for full-scale
implementation. A wide range of ion exchange media are available to selectively separate certain
contaminants. To date, no ROD has been issued which names ion exchange as a groundwater remediation
technology to address inorganic pesticide related contamination.
Performance-Currently, no specific data are available regarding the effectiveness of this method in
the remediation of inorganic pesticides in water.
Process Specifics-Implementation of ion exchange technology to remediate contaminated
groundwater is a relatively straightforward process. A typical treatment train for the remediation of
groundwater using ion exchange is very similar to a treatment train using carbon adsorption, except additional
facilities for regeneration of resins may be needed.
86
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Commercially available weak and strong acid cation exchange synthetic resins can be used to treat
groundwater contaminated with inorganic pesticide. Selective exchange materials, like natural zeolites, have
been effective in removing trace quantities of lead and arsenic from contaminated water. The depleted ion
exchange media can either be regenerated and reused or disposed of as a spent material.
Costs-A 500-gpm ion exchange unit to remove metal ions from groundwater incurred $5,500,000 in
capital costs and $730,000 in first year O&M costs (1989) [24,35].
Data Needs-Data needs for ion exchange are noted in Table 3-45.
TABLE 3-45. DATA NEEDS FOR ION EXCHANGE [99]
Data Needs
Pretreatment
Type of contaminant
Hardness (Ca, Mg)
Oil and grease
PH
Oxldants
Possible Effects
Water must be pretreated to remove suspended solids,
precipitates, and biological growth and prevent resin fouling;
suspended solids should be present at levels lower than 50
mg/L
Affects selection of ion exchange resin(s); many resins exhibit
varying levels of compatibility and selectivity
May be adsorbed by resin and increase level of backwashing
required
May clog resin and inhibit process effectiveness
May inhibit effectiveness of ion exchange resin; adsorption
varies with resin type
May damage resins
Evaporation-
Evaporation is the transformation of liquid into vapor. Evaporation techniques are suitable for a
solution that consists of a liquid and a solute which is essentially nonvolatile. The concentration of the solute
is achieved by removing the liquid as a vapor, and the residue becomes part of a concentrated liquid.
Evaporation processes can separate nonvolatile parts of contaminants from water or other solvents.
Applicability-Evaporation techniques treat pesticides from all four waste groups. Usually, evaporation
is carried out in the ex-situ mode of operation.
Status-Evaporation is a widely used and proven technology in chemical processing industries.
However, its application in environmental remediation has been limited thus far. To date, no ROD has been
issued which calls for the treatment of pesticide-contaminated water using this technique; however, this
process has the potential for use as a pesticide remediation technology.
Performance-Currentlv. no data are available regarding the performance of this energy-intensive
method in the remediation of pesticides in water.
Process Specifics-Several types of evaporators are commercially available. Figure 3-19 is a
schematic diagram of a vapor recompression evaporation system for treating pesticide-contaminated
groundwater. The concentrated liquid from the evaporator can be processed further in a crystallizer for
reduction of volume, in an incinerator for destruction, or to another treatment/disposal site for ultimate
disposal.
87
-------
Mechanical
Vapor
Recomprosslon
Evaporator
<#2#%22%^^
Concentrate
Storage Tank
HP.ISI2 IWM
Figure 3-19 Schematic for Evaporation of Pesticide-Contaminated Groundwater.
Pesticide
. Containing
Concentrate
to Further
Treatment
and Disposal
GfiSiS-Pretreatment costs include those associated with pumping and filtration. Post-treatment costs
include the treatment/disposal of concentrate. The total estimated treatment expenditures for evaporation can
range from $0.15 to $0.40 per gallon (1985) [81].
Data Needs-Data needs for vaporization are noted in Table 3-46.
TABLE 3-46. DATA NEEDS FOR VAPORIZATION
Data Needs
Heat of vaporization
Heat transfer coefficient
Thermal conductivity
Boiling point rise
Presence of volatiles and noncondensables
Possible Effects
Affects amount of energy required to evaporate liquid
Determines ratio of heat applied to heat absorbed by liquid; the
more heat absorbed by the liquid to be evaporated for a given
quantity of heat applied, the greater the effectiveness of the
process
Affects the rate at which heat is absorbed; as thermal
conductivity increases, energy absorption increases
Determined by the amount of dissolved substance in the water;
the greater the concentration of dissolved substance, the
greater the increase in boiling point; this increases the energy
required to boil the liquid
May affect requirement for off-qas treatment
88
-------
SUMMARY
The remedial options discussed in Section 3 are applicable treatment alternatives for pesticide-
contaminated soils, sediments, sludges, and groundwater. As indicated, not every treatment technology is
a viable option for all types of pesticide contamination. However, the range of treatments worth evaluating in
a given application may be greatly reduced once the contaminants of concern and their physical properties
have been identified.
Therefore, this section of the document can be used to increase the reader's general understanding
of the process specifics, status, performance, and costs associated with each of the technologies examined.
This information should enable the reader to select the most useful technologies for his or her specific needs
with the caveat that the facts contained herein are intended only as general guidelines since site-specific
characteristics, waste matrices, cleanup criteria, etc. can vary widely.
REFERENCES FOR SECTION 3
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89
-------
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90
-------
26". USEPA. 1988. Technology Screening 'Guide for Treatment of CERCLA Soils and Sludges. EPA-540-
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28. Geosafe Corporation. May 1992. In Situ Vitrification Technology Update. Richland, WA.
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No. 2473. Three Bridges, NJ.
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38. USEPA. 1991. Engineering Bulletin: Chemical Oxidation Treatment. EPA-540-2-91-025. Off ice of
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39. Helsel, R., T. Stoddart, and H. Williams. Technology Demonstration of Thermal Desorption UV
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Degradation ofDieldrin andEndrin in the Field Using Acidified Zinc, EPA-600/J-81-074.
46. USEPA. February 1990. RI/FS Treatability Study for Myers Property Superfund Site, Document
Control No. 4200-03-AAFB, Work Assignment NO-003-2LC9.
47. Dennis, Jr., W.H., and W.J. Cooper. April 1979. Nickel Boride Catalyzed Dechlorination of Several
Organochlorine Pesticides, U.S. Army Medical Bioengineering Research and Development
Laboratory, Technical Report 7702.
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of Chlorinated Benzene, AICH Summer National meeting, Paper No. 65C.
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Pesticide Disposal," Journal of Environmental Quality, Vol. 1, No. 1, January- March 1972.
50. King, J., et al. November 1985. In-Situ Treatment of Pesticide Contaminated Soil, Proceedings of
6th National Conference on Management of Uncontrolled Hazardous Waste Sites, Washington, DC.
51. Faust, S.D. and M.H. Gomaa. 1972. "Chemical Hydrolysis of Some Organic Phosphorus and
Carbamate Pesticides in Aquatic Environments," Environmental Letters, 3(3), pp. 171-201.
52. Lawless, E.W., Ferguson, T.L., Meiner, A.F. June 1975. Guidelines for the Disposal of Small
Quantities of Unused Pesticides, EPA-670/2-75-057, EPA, National Environmental Research Center,
Cincinnati, OH.
53. USEPA. April 1992. Innovative Treatment Technologies: Semi-Annual Report. EPA/540/2-91/001
54. Hall, C.V., et al. February 1982. Safe Disposal Methods for Agricultural Pesticide Wastes, EPA-
600/2-82-028, EPA, Washington, DC.
55. Freeman, HP., A.W. Taylor, and W.M. Edwards. 1975. "Heptachlor and Dieldrin Disappearance
from a Field Soil Measured by Annual Residue Determinations," Journal of Agricultural and Food
Chemistry, Vol. 23, No. 6, pp. 1101 -1105.
56. USEPA. 1990. Engineering Bulletin: Slurry Biodegradation. EPA-540-2-90-016. Office of
Emergency and Remedial Response, Washington D.C., Office of Research and Development,
Cincinnati, OH.
57. USEPA. 1991. Engineering Bulletin: In Situ Soil Flushing. EPA-540-2-91-021. Off ice of Emergency
and Remedial Response, Washington D.C., Office of Research and Development, Cincinnati, OH.
92
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58.
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71.
72.
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Unsaturated Zone Treatment Technologies. EPA-600-2-90-001. Risk Reduction Enqineerinq
Laboratory, Cincinnati, OH.
USEPA. 1991. Soil Vapor Extraction Technology Reference Handbook. EPA-540-2-91-003 Office
of Research and Development, Washington D.C.
USEPA. 1991. Engineering Bulletin: In Situ Soil Vapor Extraction Treatment. EPA-540-2-91-006
Office of Emergency and Remedial Response, Washington D.C., Office of Research and
Development, Cincinnati, OH.
USEPA. 1991. Engineering Bulletin: In Situ Steam Extraction Treatment. EPA-540-2-91-005. Office
of Emergency and Remedial Response,,Washington D.C., Office of Research and Development
Cincinnati, OH. .
Houthoofd, Janet, Guggilam Sresty, and Harsh Dev, In Situ Soil Decontamination by Radio
Frequency Heating. USEPA, Cincinnati, OH, III Research Institute, Chicago, IL.
Dev, Harsh, et al. Field Test of the Radio Frequency In Situ Soil Decontamination Process. ITT
Research Institute, Chicago IL, U.S. Air Force HQ Engineering and Services Center, Tyndall Air Force
Base, FL.
Dev, Harsh and Tom Bajzek. Hydrocarbon Removal by In Situ Heating of Soil by Electrical Enerqv.
IIT Research Institute, Chicago, IL.
Dev, Harsh, Guggilam Sresty, and Paul Carpenter. In Situ Soil Decontamination by Radio Frequency
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WESTON (Roy F. Weston). 1992. Final Rocky Mountain Arsenal In Situ Radio Frequency
Heating/Vapor Extractions Pilot Test Report. Volume 1. Contract No. DAAA 15-88-D-0023
Lakewood, CO.
URS Consultants, Inc. and Harza Environmental Services, Inc. 1992. "Pilot-Scale Soil Washing
Study, Sand Creek Superfund Site, Commerce City, Colorado." Draft Test Report. Contract No
68-W9-0053. Commerce City, CO.
Bechtel Environmental, Inc. 1990. "Feasibility Study for the FMC Fresno Plant Superfund Site
Report to MC Corp., San Francisco, CA.
USEPA. 1990. Engineering Bulletin: Soil Washing Treatment. EPA-540-2-90-017. Office of
Emergency and Remedial Response, Washington D.C., Office of Research and Development
Cincinnati, OH.
USEPA. 1991. Engineering Bulletin: Thermal Desorption Treatment. EPA-540-2-91-008. Office of
Emergency and Remedial Response, Washington D.C., Office of Research and Development
Cincinnati, OH.
Canonie Environmental Services Corporation. 1994. "Low Temperature Thermal Aeration (LTTA)
Processing." Volume 1.
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Photolysis Process for Decontaminating Soils Containing Herbicide Orange.
93
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73. D.A. Austin. 1988. The B.E.S.T. Process - An Innovative and Demonstrated Process for Treating
Hazardous Sludges and Contaminated Soils. Presented at 81st Annual Meeting of APCA, preprint
88-68.7, Dallas, TX.
74. USEPA. 1990. Engineering Bulletin: Solvent Extraction Treatment. EPA-540-2-90-013. Office of
Emergency and Remedial Response, Washington D.C., Office of Research and Development,
Cincinnati, OH.
75. USEPA. November 1990. National Survey of Pesticides in Drinking Water Well; Phase I report; EPA
570/9-90-015.
76. USEPA. Fall 1990. National Pesticide Survey, Project Summary.
77. Buescher, C.A., J.H. Dougherty, and R.T. Skride. 1964. "Chemical Oxidation of Selected Organic
Pesticides," Journal of WPCF, Vol. 36, No. 8, pp. 1005-1014.
78. Randall, T.L and P.V. Knopp. 1980. "Detoxification of Specific Organic Substances by Wet
Oxidation." Journal WPCF, Vol. 52, No. 8, pp. 2117-2130.
79. Miltner, R.J., D.B. Baker, T.F. Speth, and C.A. Frank. 1988. Treatment of Seasonal Pesticides in
Surface Waters, EPA/600/0-88/133, EPA, Water Engineering Research Laboratory, Cincinnati.
80. Dietrich, M.J., T.L. Randall, and PJ. Canney. 1985. "Wet Air Oxidation of Hazardous Organics in
Wastewater," Environmental Progress, Vol. 4, No. 3, pp. 171-177. August 1985.
81. USEPA. September 1985. Compendium of Costs of Remedial Technologies at Hazardous Waste
Sites, Final Report, Office of Emergency and Remedial Response, Washington, DC.
82. D.A. Cheuvront, C.L. Giggy, C.G. Lovan, and G.H. Swett. 1988. "Groundwater Treatment with Zero
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833-849.
83. USEPA. Engineering Bulletin: Chemical Oxidation Treatment. EPA-540-2-01-025. Office of
Emergency and Remedial Response, Washington D.C., Office of Research and Development,
Cincinnati, OH.
84. Ruzicka, J.H., J. Thomson, and B.B. Wheals. 1967. "The Gas Chromatographic Determination of
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85. USEPA. January 1990. Handbook on In-Situ Treatment of Hazardous Waste Contaminated Soil,
EPA/540/2-90/002, p. 21.
86. Faust, S.D. and H.M. Gomaa. 1972. "Chemical Hydrolysis of Some Organic Phosphorus and
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94
-------
89. Monning, E., M. Murphy, R. Zweidinger, and L. Little. April 1980. Treatability Studies of Pesticide
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90. Melcer, H. and W.K. Bedford. "Removal of Pentachlorophenol in Municipal Activated Sludge
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91. April, R. and M. Cunningham. June 1989. Best Demonstrated Available Technology (BOAT)
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Emergency and Remedial Response, Washington D.C., Office of Research and Development,
Cincinnati, OH.
94. Nye, J.C. 1984. Treating Pesticide-Contaminated Waste Water Development and Evaluation of a
System, Report No. 0097-6.56/84/0259-0153, American Chemical Society, Washington, DC,
95. Kobylinski, E.A. and W.H. Dennis. August 1983. Pesticide-Laden Wastewater Treatment for Small
Waste Generators, Technical Report No. 8203, U.S. Army Medical Bioengineering Research &
Development Laboratory, Ft. Detrick, MD.
96. Radian Corporation. November 1988. Phase I - Technical Feasibility of Methane Use for Water
Treatment: Task 2. Preliminary Economic Analysis, DCN 88-263-017-02.
97. USEPA. 1991. Engineering Bulletin: Granular Activated Carbon Treatment. EPA-540-2-92-024.
Office of Emergency and Remedial Response, Washington D.C., Office of Research and
Development, Cincinnati, OH.
98. Kincannon, D.F. and Ayoub Esfandi. February 1981. Performance Comparison of Activated Sludge,
PAC Activated Sludge, Granular Activated Carbon and a Resin Column for Removing Priority
Pollutants from a Pharmaceutical Wastewater, Proceedings of the 35th Industrial Waste Conference,
Ann Arbor Science, Ml.
99. Pontiero, F. Editor. 1971. Water Quality and Treatment. American Water Works Association. Fourth
Edition. McGraw-Hill, Inc., New York, NY.
95
-------
-------
APPENDIX A
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