REVIEW DRAFT
TECHNOLOGY SCREENING GUIDE
FOR TREATMENT OF
CONTAMINATED SOILS AND SLUDGES
Submitted to:
L:nda Galer
Office of Solid Waste and Emergency Response
Office of Emergency and Remedial Response
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
In Response to:
USEPA Contract.,No. 68-01-7053
Work Assignment No. 11
March 5, 1987
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TABLE OF CONTENTS
Section Page No.
.1 INTRODUCTION 1-1
2 WASTE CHARACTERIZATION 2-1
3 WASTE/TECHNOLOGY MATRICES 3-1
4 TECHNOLOGY SUMMARY TABLES 4-1
5 PRETREATMENT TABLES 5-1
6 APPROACH TO USE 6-1
6.1 Single Waste Contaminant 6-1
6.2 Multiple Waste Contaminants 6-2
7 APPLICATION OF THE TECHNOLOGY SCREENING 7-1
PROCEDURES TO A HYPOTHETICAL WASTE
8 REFERENCES 8-1
Property of U.S. Environmental
Protection Agency Library MD-108
FEB 41988
1200 Sixth Avenue/Seattle, WA 96101
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Table No.
LIST OF TABLES
1 Waste/Technology Matrix: Soils
2 Waste/Technology Matrix: Sludges
3 Categorization of 129 Priority Pollutants
4 Technology Summary: Soils and Sludges - High
Temperature Thermal Treatment (general)
5 Technology Summary: Soils - Fluidized Bed
Incineration
6 Technology Summary: Soils and Sludges
Infrared Thermal Treatment
7 Technology Summary: Soils and Sludges
Rotary Kiln Incineration
8 Technology Summary: Sludges - Wet Air
Oxidation
9 Technology Summary: Soils - Advanced
Electric Reactor
10 Technology Summary: Sludg«s - Evaporation/
Dewatering
11 Technology Summary: Sludges - Basic Extractive
Sludge Treatment
12 Technology Summary: Sludges - Filtration
13 Technology Summary: Soils - Soils Washing
14 Technology Summary: Soils - In-Situ Soils Flushing
15 Technology Summary: Soils - Potassium/Polyethylene
Glycol (KPEG) Dechlorination
16 Technology Summary: Soils - Low Temperature
Thermal Stripping
17 Technology Summary: Soils - In-Situ Vacuum
Extraction
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LIST OF TABLES (cont'd)
Table No.
18 Technology Summary: Soils - Cement-Based
Immobilization
19 Technology Summary: Soils and Sludges - Lime
Stabilization
20 Technology Summary: Sludges - Chemical Reduction-
Oxidation
21 Technology Summary: Sludges - Neutralization
22 Technology Summary: SIudges - Composting
23 Technology Summary: $4>ils - In-Situ
Biodegradation
24 Pretreatment Methods: Slm$^es
25 Pretreatment Methods: Soils
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LIST OF FIGURES
Figure No.
1 Fluidized Bed Incineration
2 Infrared Thermal Treatment
3 Rotary Kiln
4 Wet Air Oxidation
5 Advanced Electric Reactor
6 Evaporation/Dewatering
7 Basic Extractive Sludge Treatment
8 Filtration
9 Soil Washing
10 In-Situ Soil Flushing
11 Potassium Polyethylene Glycol (KPEG)
Dechlorination
12 Low Temperature Thermal Stripping
13 In-Situ Vacuum Extraction
14 Chemical Reduction-Oxidation
15 Neutralization
16 In-Situ Biodegradation
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1. INTRODUCTION
This guide for the screening of treatment alternatives for soils and
sludges has been developed to issist CERCLA site managers in identifying
potentially applicable treatment technologies. The guide is not designed
to select the best technology for a articular waste, but rather to
identify all of the treatment technologies potentially applicable to that
waste.
The matrices and technology summaries screen potentially applicable
technologies by:
1. Identifying the treatment technologies that appear applicable to
remediate the many types of wastes found at CERCLA sites; and
2. Identifying restrictive waste/substrate characteristics,
treatment process limitations, and pretreatment options that
must be considered when evaluating a potential treatment system
in detail.
The above infbrmation is provided in threi iroups of tables:
(1) waste technology matrices for specific waste groups, (2) technology
summary tables for each technology, and (3) pretreatment tables to
identify potential pretreatment and materials handling systems. The
tables are designed to be used by both technical and nontechnical
personnel; therefore, no specific technical background is required to
identify applicable technologies.
The tables assist in identifying waste, site, arjd technology factors
that should be considered in the evaluation or implementation of
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treatment systems. Specifically, this guide's tables identify the data
necessary for a more detailed evaluation of the technologies. Once these
data are collected, the guide can be used to identify potentially
applicable technologies warranting continued evaluation and eliminate
technologies that are not technically feasible. A more detailed analysis
of each potentially applicable alternative identified by this guide would
include cost, performance, and environmental impacts. This guide is not
meant to be used for such an in-depth analysis, but rather, is designed
to provide a preliminary screening of treatment alternatives and to
identify data needs. EPA is currently developing detailed guidance on
the in-depth evaluation of treatment alternatives for superfund wastes.
The remaining contents of this guide are organized as follows:
• Section 2 outlines the waste characterization process;
• Section 3 describes the waste/technology matrices and defines
how a technology's effectiveness was determined;
• Section 4 discusses the content and utility of the technology
summary tables;
• The purpose and use of the pretreatment tables are summarized
, in Section 5;
• A step-by step approach for the proper use of this guide is
contained in Section 6;
• Section 7 presents an example of how to use the guide with a
hypothetical waste;
• References are presented in Section 8;
• following the above sections, are the waste/technology
raatricies, Tables 1 and 2, which identify the applicability of
the technologies for each waste group;
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• Table 3 presents examples of each waste group;
• Then, for each technology a process schematic (where
available), a technology description, and a technology summary
table is presented.
• Finally, Tables 24 and 25 present pretreatment methods.
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2. WASTE CHARACTERIZATION
The potentially applicable technologies are identified on the basis
of the characteristics of the waste to be treated and (1) must be able to
destroy or remove the contaminants found in the waste and (2) must be
compatible with or applicable to the waste matrix.
Therefore, in order to properly use the matrices and tables In this
guide, data on the physical form and contaminants of the waste must be
obtained. The waste characterization process Involves Identification of
the physical form or waste matrix (soil or sludge for this guide) and the
contaminants or waste group for which treatment is required.
This guide Is designed to be used for two general categories of
physical form or matrix common to wastes encountered at CERCLA sites:
soils and sludges. For the purpose of this guide, sludges are defined as
pumpable materials of both natural and man-made origin with a solids
content of 10 to 85. percent, the remainder being liquid. Soi l.s are
defined as nonpumpable inert dirt, sand, silt, cl&y, rock, and similar
earth materials with a solids content of greater than 85 percent. Wastes
with a solids content of less than 10 percent are defined as liquids and
are not covered In this guide.
The waste contaminants or waste group(s) to be treated have to be
identified, usually through chemical analysis. The waste groups used In
this document are listed 1n the left margin of the waste/technology
matrices. Table 3 has been Included to assist the reader In selecting
2-1
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the appropriate waste group(s). The majority of CERCLA soils and sludges
will be contaminated with more than one waste group; therefore, if this
guide is to be used properly, all waste groups must be identified. Once
potential treatment methods are identified based on the information
obtained from a waste characterization, the guide can be used to
ascertain other waste characteristics that must be determined for a more
thorough evaluation of the potentially applicable alternatives.
2-2
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3. WASTE/TECHNOLOGY MATRICES
This guide contains two waste/technology matrices. Table 1 for soils
and Table 2 for sludges, designed to identify the potential applicability
and effectiveness of technologies on specific waste groups. The
waste/technology matrices assume that the user has completed the waste
characterization described in Section 2. The waste characterization
allows the user to Identify the waste as a soil or sludge and determine
the major contaminants or waste groups. The waste groups are listed
vertically down the left margin, and the technologies are listed
horizontally across the top of the tables.
The waste groups in the waste/technology matrices are organized
according to their basic chemical nature, which often reflects similar
treatability characteristics (e.g., volatility, blodegradabi1ity, Btu
content). High profile contaminants such as PCBs and pesticides are
presented separately from other halogenated organlcs because of their
unique characteristics and the special emphasis placed on their
remediation.
The following criteria were used to evaluate the applicability of the
technologies to each waste group:
1. Demonstrated effectiveness - (Symbol 9) The technology has been
used successfully on a commercial scale for treating hazardous
CERCLA waste In repeated applications (e.g., rotary k11n
Incineration of most organlcs).
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2. Potential effectiveness - (Symbol 8) The technology appears to
have the basic characteristics needed for successful application
but has not been proved for CERCLA waste on a commercial scale
or on a continuous basis. Effectiveness may depend on specific
waste or soil characteristics (e.g., soil flushing of organics),
or pretreatment may be required. Economic or environmental
feasibility Is uncertain. A decision on feasibility requires
careful consideration of waste-related limitations or mixture
interferences and may require bench and/or pilot testing.
3. No effectiveness - (Symbol 0) The technology Is not expected to
remove or destroy the contaminant to a significant degree, but
the contaminant does hot generate interference or adverse
Impacts on the process (e.g., vacuum extraction for metal
contaminated soiIs).
4. Adverse Impacts - (Symbol X) The contaminant Is likely to
generate significant Interference or adversely Impact either the
environment or the effectiveness, safety, cost, or reliability
of the treatment process (e.g., 1n-s1tu biodegradatlon for soils
contaminated with blotoxic metals or pesticides).
3-2
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4. TECHNOLOGY SUMMARY TABLES
Following the identification of potentially applicable treatment
technologies, the user should refer to the appropriate technology summary
tables to identify potentially restrictive contaminant or substrate
characteristics that can interfere with process feasibility and/or
operation. To determine whether these restrictive characteristics apply
to the specific waste to be treated, additional data on the waste or soil
may be required.
Where available, quantitative data on restrictive characteristics
have been included.-in the tables only to assist the user in evaluating
potential technologies. The data have been extracted from general and
specific sources and should only be used as a guidline or crude estimate
for applicability purposes, and are therefore not transferable to.every
application.
The data collection tasks, or at least the requisite sampling tasks,
should be undertaken early in the remedial investigation/feasibility
study (RI/FS) process. Thus, data collection will be more efficient and
economical and potential treatment alternatives can be identified early.
Also, the feasibility study process is expedited by having pertinent
treatability and/or process data available. Viable treatment
alternatives can be evaluated more efficiently, and infeasible
alternatives will be screened out early.
These tables can be used at several stages of the remedial
investigation or site sampling process to further refine the technically
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feasible treatment method. However, this guide is designed only to
screen alternatives and identify data needed to evaluate technical
feasibility. The potential technologies identified must be further
evaluated using the references provided, contacts with technology experts
(including vendors), bench and/or pilot scale testing, etc.
4-2
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5. PRETREATHENT TABLES
Identification of materials handling or pretreatment requirements
that may be applicable to the wastes under consideration is also useful.
Pretreatment, materials handling, or processing requirements for a waste
are often not recognized until the advanced stages of pilot testing or
implementation of a treatment system. This may cause significant delays
and escalate costs while the waste and/or equipment 1s modified. For
example, vendors of mobile incineration systems consider materials
handling and processing to be the key problems at a site rather than the
technical performance of the incineration system itself. Handling of
dense, viscous sludges can be particularly problematic because of
adhesion, equipment fouling, and variation in pumpability.
When materials handling requirements are identified early in the
planning process, systems can be designed or modified to handle the
particular physical or chemical characteristics of the waste. The
pretreatment tables (Tables 24 and 25) are provided to give a general
overview of materials handling systems for soils and sludges. Specific
systems are highly dependent on the characteristics of the waste and the
conditions at the site. The necessary Information on site conditions and
physical characteristics can be collected concurrently with data
collection or sampling conducted to identify restrictive chemical and
physical characteristics of the wastes.
5-1
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6. APPROACH TO USE
The use of this guide varies depending on whether the waste soil or
sludge contains one or more major contaminants or waste groups.
Therefore, the first step is to complete the waste characterization
described in Section 2. This allows the user to Identify the waste
matrix, I.e., soil or sludge, and the contaminants or waste groups in a
soil or sludge. Section 6.1 describes the approach for soils and sludges
containing a single waste group, while Section 6.2 discusses soils and
sludges containing multiple waste groups.
6.1 Single Haste Contaminant
After identifying the waste matrix and waste group (contaminant), the
user should then consult the appropriate waste/technology matrix, i.e.
Table 1 for soils or Table 2 for sludges. The next step is to find the
contaminant or waste group in the left margin, read across the table, and
list those technologies identified as having demonstrated or potential
effectiveness. Next, the technology summary table for each potential
technology should be evaluated to identify possible restrictive waste
characteristics, process limitations, and data collection requirements
needed for further evaluation. A number of tables direct the user to the
pretreatment tables, Table 24 for soils or Table 25 for sludges. These
tables contain common material handling, processing, and pretreatment
options that may eliminate or reduce restrictive waste characteristics
6-1
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6.2 Multiple Waste Contaminants
This guide can also be used to evaluate the treatability of waste
soils or sludges containing more than one contaminant or waste group.
When evaluating wastes with multiple waste groups, the first step 1s to
evaluate each waste group Independentaly, as described 1nSect1on 6.1.
The next step is to use the waste/technology matrices to compare
against the 11st of technologies Identified for the waste groups. The
Ideal solution would be to find one or more technologies that have
demonstrated effectiveness on all of the waste groups of concern. If
such a technology can be identified, its technology summary table should
be carefully evaluated against each waste group for possible restrictive
characteristics and data collection requirements.
The next best alternative would be a technology that has at least
potential effectiveness on all of the waste groups. As above, the
technology summary tables should be carefully evaluated against each
waste group.
If a single technology with demonstrated or potential effectiveness
cannot be Identified, combinations of technologies or treatment trains
that can successfully treat the waste should be Identified. A treatment
train 1s composed of two or morfe technologies used 1n series. Each
technology 1s Included to remove or destroy a certain waste group or
contaminant; therefore, each technology need be effective only on Its
target waste group. Technologies that are effective on one waste group
6-2
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but are adversely impacted by another can be used as part of a treatment
train provided the impacting waste group is treated or pretreated prior
to reaching the impacted technology. Each technology summary table
should, therefore, be thoroughly evaluated against each waste group to
identify contaminants that must be treated prior to application of
particular technologies. This step allows the user to develop the order
of the technologies within a potential treatment train.
Following review of the matrices, technology tables, and pretreatment
tables, the user should be familiar with possible treatment systems, the
restrictive waste characteristics that can affect the system, the data
collection requirements necessary to Identify potential problems, and the
pretreatment needed to resolve various waste handling problems. By using
this information and the referenced documentation, it is then possible to
initiate advanced planning for in-depth feasibility studies and/or
bench/pilot testing of potential treatment technologies.
6-3
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7. APPLICATION OF THE TECHNOLOGY SCREENING
PROCEDURES TO A HYPOTHETICAL WASTE
To illustrate the use of this guide, this section screens a
hypothetical waste for potential treatment technologies. The procedure
used is described in Section 6; the example is a soil contaminated with
trichloroethylene (TCE) and nickel.
The two waste groups are initially screened separately. From the
waste characterization, TCE Is Identified as a halogenated volatile
organic and nickel as a nonvolatile metal.
Table 1 Identifies the following technologies as having demonstrated
or potential effectiveness on soils contaminated with halogenated
volatiles such as TCE:
• Rotary kiln incineration (demonstrated);
• Cement-based Immobilization (demonstrated);
• F1u1dized bed incineration;
• Infrared thermal treatment;
• Advanced electric reactor;
• Soil washing;
• Dechlorination;
• Low temperature thermal stripping;
• Vacuum extraction; and
• In-situ biodegradation.
According to Table 1, three technologies have demonstrated or
potential effectiveness on soils contaminated with nonvolatile metals
such as nickel:
• Cement-based Immobllizatlon (demonstrated);
• Soil washing; and
• L1me stabl Hzatlon.
7-1
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Comparison of the two lists reveals three technologies that could
potentially treat both waste groups in a single step. Cement-based
immobilization is identified as having demonstrated effectiveness on both
waste groups, and soil washing and lime stabilization are potentially
effective on both waste groups.
The next step 1s to consult the technology summaries for these three
technologies to determine restrictive waste characteristics.
Cement-based Immobilization (Table 18) - The table indicates that
volatile organlcs are not effectively Immobilized and recommends analysis
for volatile organlcs and bench-scale testing. The waste
characterization has already Identified a volatile organic, TCE;
therefore, bench-scale testing would be required to further evaluate this
technology's effectiveness on TCE. No restrictive characteristics are
identified for nickel.
Lime Stabilization (Table 19) - The table states that volatile
organlcs are not Immobilized and that metals may not be permanently
immobilized.
SoU Hashing. (Table 14) - The table Indtcates the formulation of a
suitable washing fluid would be difficult for wastes containing mixtures
of organlcs (i.e., TCE) and metals (1. e., nickel). The technology's
effectiveness also appears highly dependent upon the soil's
characteristics.
From the review of the technology summary tables, It Is unlikely that
a single technology can effectively treat soil contaminated with both TCE
and nickel. Cement-based immobilization and lime stabilization cannot
7-2
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Immobilize volatile organics (TCE) and treatment of wastes containing
organics and metals would be difficult with soil washing. The next step,
therefore, Is to identify and evaluate each possible multistep treatment
process or treatment train. Obviously, there are too many possibilities
to cover here; however, one possible treatment train will be investigated
to Illustrate the process.
One possible TCE-nlckel treatment train is low temperature thermal
stripping of TCE followed by cement-based immobl1Ization of the nickel
compounds. Table 1 indicates that low temperature thermal stripping is
potentially effective on TCE but has no effect on nickel. Table 16
indicates that the technology is not effective on metals. This
restrictive characteristic would preclude the use of this technology for
removing both contaminants; however, the soil flushing segment of the
train is included only for TCE removal. No restrictive characteristics
are listed in Table 16 for volatile organics (TCE), although the
technology's effectiveness appears highly dependent on soil
characteristics. Therefore, further evaluation of this technology should
concentrate on defining site-specific soil characteristics.
The second segment of the treatment train would involve cement-based
Immobilization of the nickel. Table 18 states that volatile organics are
not effectively immobilized. However, the majority of the volatile
organic, TCE in this example, would have been removed by the low
temperature thermal treatment step of the treatment train. Furthermore,
this segment of the treatment train Is only targeted at nickel removal,
and therefore, its effectiveness on TCE is not Important.
7-3
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Based upon the Information contained in this guide, a low temperature
thermal treatment/cement-based immobilization treatment train would
appear to be potentially feasible and warrant further investigation as
part of a RI/FS.
7-4
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8. REFERENCES
(1) Akers, C.K., R.J. Pilie, and J.G. Michalouic. 1981. Guidelines for
the Use of Chemicals in Removing Hazardous Substance Discharges.
EPA - 600/52-81-25.
(2) Ellis, W.O., and J.R. Payne. The Development of Chemical
Countermeasures for Hazardous Waste Contaminated Soil. Oil and
Hazardous Materials Spills Branch, U.S. EPA Edison, N,J. 08837.
(3) In Situ Flushing and Soils Washing Technologies for Superfund
Sites: Presented at RCRA/Superfttnd Engineering Technology Transfer
Symposium by HWERL, U.S. EPA, Cincinnati, Gfeio 45268 1985.
(4) EPA. 1986. Mobile Treatment Technologies for Superfund Wastes, by
Office of Solid Waste and Emergency Response. #540/2-86/003(f)
Washington D.C. 20460.
(5) EPA. 1979. Survey of Solidification/Stabilization Technology for
Hazardous Industrial Waste by Environmental Laboratory - U.S. Army
Engineer Waterways Experiment Station, Vicksburg, Miss. #600/2-
79/056.
(6) EPA. 1985 Handbook - Remedial Action at Waste Disposal Sites.
Hazardous Waste Engineering Research Laboratory - Office of Research
and Development US EPA Cincinnati, Ohio. #625-6-85-006.
(7) Roy F. Weston, Inc. In Situ Air Stripping of Soils Pilot Study, Roy
F. Weston, Inc., under contract to U.S. Army Toxic and Hazardous
Materials Agency Aberdeen Proving Ground, Edgewood, Md. 21010.
(8) Malot, J. 1985. Vacuum Extraction of VOC Contamination in Soils,
Terra Vac, Inc., P.O. Box 550 Dorado, Puerto Rico 00646.
(9) Noland, N.W., N. McDevitt and D. Koltuniak. Low Temperature Thermal
Stripping of Volatile Organic Compounds from Soils, 1985. U.S. Army
Toxic and Hazardous Materials Agency, Aberdeen Proving Ground,
Edgewood, Md. 21010.
(10) EPA. 1986. Superfund Treatment Technologies: A Vendor Inventory by
Office of Solid Waste and Emergency Response, Washington, D.C:
20460. #540/2-86/004.
(11) Versar, Inc. 1985. Assessment of Treatment Technologies for
Hqazardous Waste and Their Restrictive Waste Characteristics, Vol.
1A-D for EPA Office of Solid Waste, Washington, D.C. 20460.
(12) Niessen, Walter R. 1978. Combustion and Incineration Processes.
Marcel Dekker, Inc., New York.
8-1
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(13) Personal Communication with Robert Peterson, Galson Research Corp.,
December 22, 1986.
(14) Berkowitz, J., et al. 1978. Unit Operations for Treatment of
Hazardous Industrial Wastes.
(15) Allen, C. and Blaney, B. 1985. Techniques for Treating Hazardous
Wastes to Remove Volatile Organic Constituents. Hazardous Waste
Management.
(16) Personal Communication with Larry Weimar, Resources Conservation
Co., El 1icott City, Md. December 17, 1986.
(17) Versar, Inc. 1986. Assessment of Technological Options for
Management of Hazardous Wastes: Chemical Monographs for the First
Third P and U Waste Codes. Vol. 1. Washington, D.C.: U.S.
Environmental Protection Agency, Office of Solid Waste.
(18) Personal Communication with Darrell B. Oerrington, Jr., P.E.,
Versar, Inc., February 2, 1987.
8-2
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Technology
TABLE 1
WASTE / TECHNOLOGY MATRIX
SOILS
Contaminant
Organic
Halogenated Volatiles
Halogenated Non-Volatiles
Non-Halogenated Volatiles
<>lon-Halogenated Non-Volatiles
PCBs / Dioxins
Pesticides
Organic Corrosives
Inoraanir.
Volatile Metals (Cd, Zn, Ag, Hg, Sn, Pb)
Non-Volatile Metals (Cr, Ni, Cu, Be)
Asbestos
Radioactive
Inorganic Corrosives
Nonmetallic Toxic Elements (As, F, Sb, Bi)
Jyanides
Reactive
Oxidizers
Reducers
Explosives
TABLE #
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-------
TABLE 2
Technology
VvaSTE/TECHNOLOGY MATRIX
SLUDGES
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Organic TABLE #
5 6 7 8
10 11 12
18 19
20 21
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Halogenated Non-Volatiles
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Table 3.
HALOGENATED VOLATILES
Carbon tetrachloride
Chlorobenxene
1,2-D1chloroobenzene
1.1.1-Trlchloroethane
1,1-dlchloroethane
1.1-D1chloroethylene
1.1.2-Trlchloroethane
1,1,2,2-Tetrachloroethane
Chloroethane
2-Chloroethyl Vinyl Ether
Chloroform
1.2-D1chloropropane
1.3-D1chloropropene
Methylene Chloride
Methyl chloride
Methyl bromide
Bromoform
D1 chlorobromomethane
D1 chlorod1f1uoromethane
Ch1orod1bromomethane
Tetrachloroethylene
Trlchloroethylene
Vinyl Chloride
1,2-trans-D1chloroethylene
B1 s(Chloromethyl)ether
HALOGENATED NONVOLATILES
1.2-D1-chlorobenzene
1.3-D1-chlorobenzene
1.4-D1-chlorobenzene
Hexachlorobenzene
Hexachloroethane
Hexachlorobenzene
1.2.3-Trlchlorobenzene
B1 s(2-Chloroethyoxy)methane
2-Chloronaphthalene
4-Bromophenyl Phenyl Ether
4-Chlorophenyl Phenyl Ether
3,3-D1c h1orobe nz1d1ne
B1s<2-Chloroethyl> Ether
Hexachlorocyclopentadlene
Bfs(2-Chloro1sopropyl> Ether
Waste Group Examples
NONHALOGENATED VOLATILES
Acrolein
Acrylonltr1le
Benzene
Toluene
Ethylbenzene
NONHALOGENATED NONVOLATILES
Naphthalene
Isophorane
Nitrobenzene
2,4-D1n1troto1uene
2,6-D1n1trotoluene
B1s(2-Ethylhexyl)Phthalate
D1-n-octy1 phthalate
Dimethyl phthalate
Diethyl phthalate
D1-n-butyl phthalate
Acenaphthylene
Acenaphthene
Butyl Benzyl phthalate
Fluorene
Fluoranthene
Chrysene
4,6-D1n1tro-o-creosol
•2,4-D1methylphenol
Pyrene
Phenanthrene
Anthracene
Benzo(a>anthracene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
BenzoCa)pyrene
IndenoCl,2,3-c,d)pyrene
D1benzo(a,h)anthracene
Benzo(g, h, 1)pery1e ne
Benzidine
1,2-D1phenylhydraz1ne
N-N1trosodlphenyl amine
N^N1 trosodl tnethyl ami ne
N-Nltrosodlmethylamlne
N-N1trosodl-n-propylamine
Phenol
2-N1trophenol
4-N1trophenol
2,4-D1n1trophenol
-------
Table 3. (continued)
PESTICIDES
Endosulfan (2 isomers)
Endosulfan Sulfate
BHC (4 isomers)
Aldrin
Dieldrin
4,4'-DDE
4,4'-DDD
4,4'-DDT
Endrin
Endrin Aldehyde
Heptachlor
Heptachlor Epoxide
Chlordane
Toxaphene
VOLATILE METALS
Cadmium
Zinc
Si lver
Mercury
Tin
Lead
NONMETALLIC TOXIC ELEMENTS
Arsenic
Antimony
OTHER CATEGORIES
Asbestos
INORGANIC CORROSIVES
Hydrochloric acid
Nitric acid
Hydrofluoric acid
Sulfuric acid
Sodium hydroxide
Calcium hydroxide
Calcium carbonate
Potassium carbonate
fxplosives
Trinitrotoluene (TNT)
CycloSr"?methylene trinitramine (RDX)
prRs/DIOXINS
Arochlor (1016, 122^' !232'
1242, 1248, 1254, 1264)
2%, 7,8-Tetrachl oro-d 1 benzo-p-
dioxln (TCDD)
npr.AMTr CORROSIVES.
Acetic acid
Formic acid
Acetyl chloride
Aromatic Sulfonic acids
NONVOLATILE METALS
Chromlum
Nickel
Copper
Beryllium
Selenium
padioactives
Radioactive Isotopes of
Iodine, Barium, Uranium
CYANIDES
Cyanide
Metallic cyanides (ferrlcyanide,
sodium cyanide)
OXIDIZERS
Chlorates
Chromates
REDUCERS
Sulfides
Phosphides
Nitrides
-------
0U5g
Table J. Technology Summary
Waste Type: Soils and Sludges
Technology: High Temperature Thermal Treatment (General)
Waste cnaracteristics
impacting process
T ccS '.L> 1 1 Ity
Data
collect ion
Reason for restriction requirements Reference
High moisture content
Moisture content affects
handling and feeding and
has major impact on process
energy requirement.
Percent moisture
12
Elevated levels of
halogenated organic
compounds
Halogens form HC1, HBr, or Quantitative
HF when thermally treated;
acid gases may attack
refractory material and/or
impact air emissions.
analysis for
organic CI, Br,
and F
4,10,11
Presence of PCBs,
Dioxins
PCBs and dioxins are
required to be incinerated
at higher temperatures and
long residence times.
Thermal systems must
receive special permits for
incineration of these
wastes.
Analysis for
priority pollutant
4.10
Presence of toxic
elements
Presence of other toxic
elements (e.g., Cr, Ni,
Be, Cu)
Elements (either pure
or as oxides, hydroxides,
or salts) that volatilize
at high temperatures
(e.g., Cd, As, Hg, Pb,
Sn, Ag) may vaporize
during incineration.
These emissions are
difficult to remove
using conventional air
pollution control
equipment.
Elements cannot be broken
down to nonhazardous
substances by any treatment
method: Therefore, thermal
treatment is not useful for
soils with heavy metals as
the primary contaminant.
Additionally, an element
such as trivalent chrom-ium
(Cr+^) can be oxidized
to a more toxic valence
state, hexavalent chromium
(Cr*®), in combustion
systems with oxidizing
atmospheres.
Analysis for heavy 4,10,11
metals
Analysis for heavy 4,10,11
metals
-------
014Sg
Table 4. (continued)
Waste Type: Soils and Sludges
Technology: High Temperature Thermal Treatment (General)
Waste character 1stics Data
impacting process collection
feasibility Reason for restriction requirements Reference
Elevated levels of During combustion Analysis for 4,10
organic phosphorus processes, organic phosphorus
compounds phosphorus compounds form
phosphoric acid anhydride
(P2O5)• which contributes
to refractory attack and
slagging problems.
-------
8OLID RAW
FEED IN
AUXILARY FUEL
LIQUID FUEL
ATOMIZER
TO
ATMOSPHERE
INLET
RECEIVING TANK
SOLIDS FEEDER
FROM
ATM08PHERE
BAQHOU8E OR
WET 8CRUBBER
|cOMBU8TION
AIR
HID
FLUIDIZED
BED
\\v-y.:-:s\
¦:->f nY.il!
MEAT
EXCHANQER
PREHEATED
COMBU8TION AIR
8OLID8 TO
WA8TE DISPOSAL
. 8AN0 .
md STORAGE
T
8AND 8UPPLY
IN
8PENT SAND
OUT
SOURCE: CDM
Figure 1. Fluidized Bed Incineration
Technology Description
Fluidized bed Incinerators are used to Incinerate organic solids, sludges,
slurries, and liquids. Contaminants such as halogenated and nonhalogenated
organlcs. PCBs, and phenolic wastes can be potentially processed. Fluidized
bed systems can also process contaminated soil.
The fluidized bed consists of a refractory lined vessel containing a bed
of Inert granular material, such as silica sand. Combustion air 1s forced
upward through the bed, heating the granular bed. Waste material 1s injected
radially Into the bed and quickly heated, dried, and burned. The heat of
combustion from the waste 1s transferred back to the bed. Secondary
combustion chambers are employed to permit adequate time for complete
combustion. If contaminated soil 1s being processed, the soil acts as a bed
material. Detoxified soil 1s withdrawn from the bottom of the fluidized bed.
-------
004 bo
Table 5. Technology Summary
Waste Type: Soils and Sludges
Technology: Fluidized 6ed Incineration*
Waste character liti
ii'oacting process
f ea i, 1 b 1111>
Reason for restriction
Data collection
requirements
Reference
Feed particle size
Lo.v-melt ing point
(less than 1600 F)
constituents, partic-
ularly alkali metal
s.n'its ana halogens
Large particle size
affects feeding and
solids removal from the
bed. Solids greater
than 1 inch (2.5cm) must
be reduced in size by
shredding, crushing, or
grinding (see Tables
24 and 25). Soil feeds
containing fine parti-
cles (clays, silts) result
in high particulate
loading in flue gases.
Defluidization of the
bed may occur at high
temperatures when par-
ticles begin to melt and
become "sticky." Melt-
ing point reduction
(eutectics) may also
occur. Alkali metal
salts greater than 5%
(dry weight) and halo-
gens greater than 8%
(dry weight) contribute
to such refractory
attack, defluidization,
and slagging problems.
Size, form,
quantity of solid
material. Size
reduction
engineering data.
Soil particle
size distribution,
USGS soil
classif icat ion
4,10.11,12
Ash fusion
temperature
4.11
Ash content
Ash contents greater than
64% can foul the bed.
Ash content
11
Waste density
As waste density in-
creases, particle size
must be decreased for
intimate mixing and '
heat transfer to occur.
Waste-bed density
comparison
11
Presence of
cnlormated or
sulfonated wastes
Tnese wastes require
the addition -gf sorbents
such as lime or sodium
carbonate into the bed
to absorb acidic gases.
Analysis for
priority pollu-
tants
11
* See also: Table 4, High TemperJture .Theniia 1 Treatment (General)
-------
OCESStNQ/OE-WATeftlNQ
Figure 2. Infrared Thermal Treatment
Technology Description
Infrared processing systems are designed to destroy hazardous wastes with
infrared energy generated from heating elements. Most types of solid wastes
and sludges (Including contaminated soils and spent activated carbon) can be
treated with the total system (I.e., Including use of the primary and
secondary combustion chamber). Liquids and gaseous wastes may also be
processed.
Wastes travel on a woven, metal alloy conveyor belt through the furnace
for a precise residence time. After the wastes pass under Infrared heating
elements, ash residue 1s discharged to a hopper and the off-gases are
exhausted to a secondary chamber (fired with oil or gas) to ensure complete
combustion. Exhaust gases from.the secondary chamber then pass through
appropriate air pollution control equipment prior to release through a stack.
-------
014 5g
Table 6. Technology Summary
Waste Type: Soils and Sludges
Tecnno'iogy: Infrared Thermal Treatment*
Wjtie cnaracterlitics Data
impacting process collection
feasibility Reason for restriction requirements Reference
Nonhomogeneous feed s ize
Nonuniform feed size
affects remediation,
feeding, and conveyance
through the system. The
largest solid particle
size processable is 1 to
1-1/2 inches (such as
rocks, roots, containers);
must be crushed or shredded
to allow for feeding.**
Size, form, 10
quantity of solid
material. Size
reduct ion
engineering data
Moisture content Since waste material is Percent moisture 10
conveyed through the
system on a metal
conveyor belt, soils and
sludges must be firm
enough (usually >2Z%
solids) to allow for
proper conveyance. Soils
and sludges with excess
water content (e.g.,
lagoon sediments) require
dewatering prior to
feeding.**
* See also: Table 4. High Temperature Thermal Treatment (General).
** See Tables 24 and 25.
-------
SOURCE:
ENSCO ENVIRONMENTAL SERVICES
Figure 3. Rotary K1ln Incineration
Tprhnnioov Description
Rotary kiln Incinerators are Inclined, refractory-lined cylinders used
primarily for the combustion of organic solids and sludges. Including
contaminated soils.
Wastes are Injected Into the high end of the kiln and passed through the
combustion zona as the kiln rotates. Rotation of the combustion chamber
creates turbulence and Improves the degree of burnout of the solIds. Wastes
are substantially oxidized to gases and Inert ash within this zone. Ash 1s
removed at the bottom end of the kiln. Flue gases are passed through a
secondary combustion chamber and then through air pollution control units for
particulate and acid gas removal.
Although organic solids combustion Is the primary us* of rotary kiln
Incinerators, liquid and gaseous organic wastes can also be handled by
Injection Into either the feed end of the kiln or the secondary chamber.
Wastes having high Inorganic slat content (e.g.. sodium sulfate) are not
recommended for Incineration In this manner because of the potential for
degradation of the refractory and slagging of the ash. Similarly, the
combustion of wastes with high toxic metal content can result in elevated
emissions of toxic air pollutants, which are difficult to collect with
conventional air pollution control equipment.
-------
0046g
Table 7. Technology Suirmary
Waste Type: Soils and Sludges
Technology: Rotary Kiln Incineration*
Wjitc character lit ics
impact, inr, process
r'eas lb 11 it y
Reason for restriction
Data col lection
requirements
Reference
Oversized debris such
as rocks, tree roots,
fiber, and steel drums
Difficult to handle and
feed; may cause refractory
loss through abrasion. Size
reduction equipment
such as shredders must
be provided to reduce solid
particle size.** Most current
systems have a maximum feed
chute opening of 13 inches.
Size, form,
quantity of over-
sized debris.
Size reduction
engineering data
4,10.11
Alkali metal salts,
particularly sodium and
potassium sulfate
Cause refractory attack
and slagging at high
temperatures. Slagging
can impede solids re-
moval from the kiln.
% Na, K
4,11
t-'ine particle size of
of soil feeds such as
c lay. silts
Results in high
particulate loading
in flue gases due to the
turbulence in the rotary
kiln.
Soi 1 particle size
distribut ion,
USuS so i 1
classification
11,12
Spherical or
cylindrical wastes
Such wastes may roll
through the kiln before
complete combustion can
occur.
Physical inspection
of the waste
11
Ash fusion temperature
of waste
Operation of the kiln
at or near the waste
ash fusion temperature
can cause melting and
agglomeration of in-
organic salts.
Ash fusion
temperature
11
Heating value of waste
Auxiliary fuel required
to incinerate wastes with
a heating value of less
than 8,000 Btu.
Btu content
17
* See also: Table 4, High Temperature Thermal Treatment (General).
** See Tables 24 and 25.
-------
. 0X1DIZABLE
WASTE
FED
PUMP
PROCESS
HEAT
EXCHANGER
REACTOR
PCV
AIR
COMPRESSOR
OXIDIZED
WASTEWATER
SOURCE: ZIMPRO, INC.
Figure 4. Wet A1r Oxidation
Technology Description
Wet air oxidation 1s a thermal treatment technology that breaks down
organic materials by oxidation In a high temperature, high pressure, aqueous
environment. Wet air oxidation Is used primarily to treat biological
wastewater treatment sludges. It has. however, potential application to
concentrated waste streams containing organic and oxldlzable Inorganic wastes
(including halogenated organlcs. Inorganic/organ1c sludges. 1norgan1c/organ1c
cyanide, and phenols).
In this process. waste 1s mixed with compressed air. The waste-air
mixture passes through a heat exchanger and then into the reactor where
exothermic reactions Increase the temperature to a desired level. The exit
stream from the reactor 1s passed through the heat exchanger, heating the
Incoming material. A separator 1s then used to separate the resultant gas
stream (primarily air and carbon dioxide) from the oxidized liquid stream.
-------
014 Sg
Table 8. Technology Summary
Waste Type: Sludges
Technology: Wet Air Oxidation
Waste character in ics Data
impacting process collection
feasibility Reason for restriction requirements Reference
Solids content
Solids should not unduly Physical
foul heat transfer inspection
surfaces.
4.10
Viscosity of sludge
The waste must be in a
pumpable liquid or liquid-
like form, with a viscosity
of less than 10.000 SSU.
Viscosity, total
solids analysis
4,10
COD J 15,000 mg/1iter
COD : 200,000 mg/1iter
Wastes with COD concentra-
tions outside this range
are either too dilute or
too concentrated for a
feasible application.
COD analysis
4,10
Toxic metals
Toxic metals are not
treated, but are passed
through the system.
Analysis for
heavy metals
10
Abrasive and/or acidic
characteristics
Wastes that have high
abrasive and/or acidic
characteristics (e.g.,
titanium) may require
more expensive equipment
and materials.
Treatability
testing
4,10
Highly chlorinated
organics (e.g., PCBs)
Highly chlorinated organics Analysis for
are not effectively t organic
destroyed by this process chlorine
due to the relatively low
operating tempertures.
4.10
Organic content Uncatalyzed systems can Analysis for total 11
treat wastes containing up organic carbon
to 3% organics, catalyzed
systems can treat wastes
containing up to b%
organics.
-------
Figure S. Advanced Electric Reactor
Tffttng1nov Description
An advanced electric reactor (AER) 1s a relatively new thermal technology
being developed specifically for the detoxification of contaminated soils,
although other solid and Hqutd wastes may also be destroyed. The destruction
1s achieved In a reactor vessel where Intense radiation is used to reduce
toxic compounds to their elemental constituents.
The reactor vessel consists of a porous carbon core surrounded by carbon
electrodes. The core and electrodes are enclosed by a radiation heat shield
Inside a double wall cooling Jacket. Reactants are isolated from the reactor
core by a gaseous blanket that 1s formed by nitrogen flowing radially inward
through the porous core wall. The inert gas also serves as a heat transfer
medium.between the electrodes and the core.
For solid waste treatment, the solid feed 1s introduced at the top of the
reactor with a metered screw feeder. The wastes pass through the Core via
gravity where they are exposed to a temperature of approximately 4000°F. the
exit gases and waste solids from the reactor then enter two post-reactor
treatment zones to ensure complete destruction. After passing through these
zones, the remaining solid residue 1s collected In a bin. Exit gases pass
through air pollution control equipment for removal of particulates and other
emissions prior to discharge.
-------
017 lg
TABLE S. Technology Summary
Waste Type: Soils
Technology: Advanced Electric Reactor*
Waite characteristics
impacting process
feasibi 1 lty
Reason for restriction
Data collect ion
requirements
Reference
Feed part icle size
Size reduction is required,
nominally to -10 mesh. Destruction
removal efficiency is a function
of particle size, and tests have
not been performed to determine
maximum particle size at given
destruction rates.
Particle size
distribution
16
Maintainability
and reliability
Full-scale units need to be
operated in the field to
demonstrate technology
effect iveness.
F ield operat ing
data
Its
Sludge wastes
Can be fed; however, require
extensive feed pretreatment
(i.e., solidification of sludges).
Treatment data
for sludges
16
*See also: Table 4, High Temperature Thermal Treatment (General)
-------
TYPICAL SINGLE EFFECT EVAPORATOR - FALLING FILM TYPE
* SOURCE: CDM
Figure 6. Evaporat1on/Dewater1ng
¦
Technology Description
Evaporation/dewaterlng is a unit process used to reduce the moisture
content of liquid solutions, slurries, or sludges by vaporizing the more
volatile components of the waste. The result of this process Is a
concentrated slurry or semi-sol1d that can be handled and treated more
effectively.
An agitated th1n-f1lm evaporation process 1s most cmmonly used for
evaporation/dewaterlng. Basically, this system consists of a Urge diameter
heating surface on which a thin film of material 1s continuously wiped. The
volatile components are vaporized leaving concentrated sem1-solIds behind.
The process works efficiently only when applied to liquid solutions,
because solids tend to foul the heat transfer surfaces as the volatile
components are driven off. special techniques have been developed to counter
this problem (e.g.. the Carver-Greenfteld Process), but there Is little or no
experience 1n the application of these techniques to the processing of CERCLA
wastes. Dewaterlng of sludges with a Mgti solids content can be better
accomplished using the filtration techniques described in Figure S and
Table 11.
-------
0048g
Table 10. Technology Summary
Waste Type: Sludges
Technology: Evaporat ion/Dewatering
Waste chjra^teristici
impacting
f easibi 1 uy
Reason for restriction
Data collection
'requirements
Reference
Sludge viscosity
greater than iOO
poise
Thickness of sludge
prevents organics from
volatilizing effectively.
Viscosity
15
Size of solids in
sludge >2.5 ram
Solids >2.5 mm do not fit
below the clearance of
agitator blades.
Analysis of solids
size
15
Reactive wastes
that polymerize
Cause foaming and
restrict dewatering.
Analysis for
priority pollu-
tants
Finely divided
sol ids
Become entrainer in
vaporized organics.
Total suspended
sol ids
Certain si/'c'jted
organic compounds,
i.e., ammonium lauryl
sulfate, sodium
lauryl sulfate
Sulfates can cause foaming
and entrainment of solids.
Sulfate analysis
Variation in waste
composition
Evaporation/dewatering
is not selective.
Hazardous and nonhazard-
ous wastes may not be
completely separated.
Statist ical
sampling, analysis
for priority
pollutant
14
Dissolved sol ids
Crystallization of dissolved
solids forms an insulating
layer on the equipment,
thereby inhibiting heat
transfer.
Total dissolved
solids
11
Boiling point
Technology most effective
on wastes with boiling
points less than 200 C.
Boiling point
11
Suspended solids
High solids content can
cause erosion of the
equipment.
Total suspended
solids
11
Vapor pressure
Technology most effective
on low vapor pressure
wastes.
Vapor pressure
11
-------
SOURCE: RESOURCE CONSERVATION COMPANY
Figure 7. Basic Extractive Sludge Treatment
Technology Description
The Basic Extractive Sludge Treatment (BEST) process 1s used to separate
contaminants from hydrocarbon sludges. It can be modified to handle a range
of sludge types containing Insoluble, organlcs and water.
In the BEST units, an aliphatic amine solvent Is mixed at low temperature
With oil and water present 1n many sludges. The solvent breaks oil-water
emulsions and releases bound water. The solids are separated 1n a centrifuge
or filter and sent to a dryer from which the solids emerge free of oil, water,
and amine solvent.
The aliphatic amine solvent solution 1s then warmed, resulting in the
separation of solvent and oil from the water. This allows the water to be
removed for biotreatment. The remaining solvent and oil are separated by
stripping to recover the solvent for recycle.
-------
014 :,g
Table 11. Technology Summary
Waste Type: Sludges
Technology: Basic Extractive Sludge Treatment
Waste characteristics Data
impacting process collection
feasibility Reason for restriction requirements Reference
Presence of high
molecular weight
asphaltic compounds
Acidic pH
Presence of elevated
levels of volatiles
Metal compounds soluble
in organics (e.g.
tetraethyl lead)
Metals (e.g. aluminum) or
other compounds reacting
under highly alkaline
conditions.
Requires excessive time
for breakdown of sludge
by solvent.
Metals removal optimized
at alkaline pH. Sludge pH
adjustment required.
Volatiles combine with
process solvent requiring
an additional separation
step.
MfctaIs wi11 not be
separated from organic
phases during treatment.
Uncontrolled reactions may
occur during treatment
process due to alkaline pH.
Full physical 16
characterization
of sludges
pH and alkalinity 16
measurement
Volatile organic 16
analysis
Pi lot test ing 16
Metals analysis 16
Presence of highly water
soluble organics (e.g.
acetone, methyl ethyl
ketone)
Organics soluble in water
will not be separated by
process solvent.
Solubility data 16
for organics
-------
Packaged granular madia gravity filter.
Wash Trough
V
Adjustable Weir
Influent
Piping
Backwash
Inlet
Backwash
Effluent
Note:
Arrows Indicate Route
of Backwash
Vacuum filter.
Rotary
Drum
SOURCE: CDM
Figure 8. Filtration
Tfchnmoqy 0«crlPtlQn
The two primary uses of filtration processes are: (1) removal of
suspended solids from a fluid by passage of the fluid through a bed of
granular material, and (2) dewaterlng of sludges and oils using a vacuum, high
positive pressure, or gravity system. It should be noted that filtration Is
not a destructive process, as it does not separate hazardous and nonhazardous
wastes. Filtration 1s often used as a pretreatment operation to Increase the
suspended solids content of sludges, thereby reducing the volume of sludge
that must be treated.
Pressurized and gravity fed granular media filtration system are used for
aqueous waste streams containing suspended solids.
Vacuum, belt press, and chamber pressure miration piare
primarily used to dewater sludge.
-------
0145g
Table 12. Technology Sunmary
Waste Type: Sludges
Technology: Filtration
Waste cnaractenst lcs Data
impacting process collection
feasibility Reason for restriction requirements Reference
Solids contents
of sludge (<5~A)
Require pretreatment
operation that will
increase solids
concentration.
Settling/
thickening
characterist ics,
bench-scale
testing
Toxicity of sludge
Filtration is a
non-destructive
process. After
filtration, a highly
concentrated sludge
must be treated.
Analysis for
priority
pollutants
Variation in waste
compos it ion
Filtration is not
selective. Hazardous
and nonhazardous
wastes are not
separated. Additional
treatment is necessary.
Statistical
sampling, priority
pollutant
analysis
F i ltrat lor,
Clogging of fiIter
media necessitates
addition of chemicals
to improve dewatering
characteristics.
Pilot scale test
Oil and grease
content
Oil and grease con-
centrates of greater
than 200 ppm will
adversely affect
filtration.
Oil and grease
analysis
17
Particle size
Viscosity
To achieve solid/liquid
separation, the
particles must be much
larger than the size of
the filters pores-.
Filters are limited
to pumpable waste
streams with a
viscosity of less than
10.000 SSU.
Particle size
distribution,
filter pore
size (from
manufacturer)
Viscosity
11
11
Suspended solids
Most filters can
treat sludges with
suspended solids of
10 to 20%.
Tota 1
suspended solids
11
-------
~2mm SCRUBBED SOIL
SPENT
CARBON
SOURCE: EPA
Figure 9. Soil Uashing
Technology Description
The soil washing process extracts contaminants from sludge or soil
matrices using a liquid medium as the washing solution. This process can be
used on excavated soils that are fed into a washing unit.. The washing fluid
may be composed of water, organic solvents, waster/chelating agents,
water/surfactants, acids, or bases, depending on the contaminant to be removed.
Contaminated soil enters the system through a feeder where oversized
non-soil materials and debris that cannot be treated are removed with a coarse
screen. The waste passes into a soil scrubber where It 1s sprayed with
washing fluid. Soil particles greater than 2 mn in diameter leave the
scrubber and are settled en a drying bed. The remaining soil enters a
countercurrent chemical extractor where washing fluid 1s passed countercurrent
to it, removing the contaminants. The treated solids are then settled on a
drying bed. The remainder of the process 1s a multistep, treatment for removal
of contaminants from the washing fluid prior to its recycling.
-------
014 5cj
Table 13. Technology Summary
Waste Type: Soils
Technology: Soi1 Washing
Waste characteristics
impacting process
feasibility
Reason for restriction
Data
collection
requirements
Reference
Unfavorable separation
coefficient for
contaminant
Excessive volumes of
leaching medium required.
Equilibrium
partition
coefficient
Complex mixtures of waste Formulation of suitable
types (e.g., metals with washing fluids difficult,
organics)
Analysis for
priority
pollutants,
solubility data
Variation in waste
composit ion.
May require frequent
reformulation of washing
fluid.
Statistical 4
sampling, analyses
for priority
pollutants
Unfavorable soil
characteristics
- High humus content
Inhibition of desorption.
Analysis for
organic matter
1.2,3.4
- Soil, solvent reactions
May reduce contaminant
mobility.
Pilot testing
3.4
- Fine particle size
(siIt and clay)
Fine particles difficult
to remove from washing
fluid.
Soil particle size
distribution. USGS
soil classification
Unfavorable washing fluid
characteristics
- Difficult recovery of
solvent or surfactant
High cost if recovery low.
Bench-scale
test ing
- Poor treatability of
washing fluid
Requires replacement of
washing fluid.
Bench-scale
testing, conven-
tional analysis*
Reduction of soil
permeabi1ity
Surfactant adheres to soil
to reduce effective
porosity.
Permeability
pilot testing
-------
0 ] 4 Sg
Table 13. (continued)
Waste Type: Soils
Technology: Soil Washing
Waste characteristics Data
impacting process collection
feasibility Reason for restriction requirements Reference
High toxicity of Soil may require additional Toxicity of
washing fluid treatment for detoxifica- washing fluid
tion. Fluid processing
requires caution.
Conventional analysis should include organic content (i.e., BOD. COD, TOC), solids content
iron, manganese, and leachate pH.
-------
Contaminant I Re-injection of
Treatments I Treated
Removal [Groundwate^
RECYCLED
GROUND
WATER
[—1 CONTAMINANT
Source: FMC Aquifer Remediation Systems
ORIGINAL
WATER TABLE
<
<
: csure 10. In-Situ So 1 Flushing
. "?c.-r,; lcav Description
Sot) flushing is a process applied to unexcavated soils using a ground
water extract ion¦re-injection system. The technology is often used for
removal of volatile organics from permeable soils.
Fi.mp jnd treatment systems for ground water are often combined with re-
injection of treated grouno water upgradient of the extraction wells to
produce accelerated flushing and decontamination of soils in situ.
Surfactants or chelating agents may be added to the re-injecteo ground water,
provided these compounds do not pose risks of additional contamination.
I
-------
014Sg
Table 14. Technology Summary
Waste Type: Soils
Technology: In-Situ Soil Flushing
Waste characteristics
impacting process
feasibility
Reason for restriction
Data
collection
requirements
Reference
Presence of:
- metals
- heavy orgamcs
Flushing process only
effective for mobile or
soluble contaminants.
Analysis for
priority
pollutants
Unfavorable separation
coefficient for
contaminant
Excessive voliases of
surfactants required.
Equl1ibrium
partition
coefficient
Complex mixtures of waste
types (i.e., metals with
organ-,cs)
Formulation ef suitable
washing fluids
difficult.
Analysis for
priority
pollutants,
elemental analysis
Variation in waste
composition
May require frequent
reformulation of washing
fluid.
Statistical
sampling, analyses
for priority
pollutants
UnfavoraDle soil
characteristics
Variable soil
conditions
Inconsistent flushing.
Soil mapping
3.4
- High organic content
Inhibition of desorption.
Analysts for 1,2,3,
organic matter
- low permeability (high Reduces percolation,
clay content)
Percolation test- 1.4
Soil, solvent reactions May reduce contaminant
mobility.
Pilot testing 3.4
Unfavorable site hydrology Groundwater flow must
permit recapture of soil
flushing fluids.
Site hydrogeology 3.4
must be well
defined
Unfavorable washing fluid
characteristics
- High toxicity or
volatility
Health risks.
Solvent
characterization
3.4
-------
C145g
Table 14. (continued)
Waste Type: Soils
Technology: In-situ Soil Flushing
Wast* characteristics Data
impacting process collection
feasibility Reason for restriction requirements Reference
Difficult recovery of
solvent or surfactant
Poor treatability of
washing fluid
High cost 1f recovery low.
Requires replacement of
washing fluid.
Bench-scale
testing
Bench-scale
testing, conven-
tional analysis*
Reduction of soil
permeability
Surfactant adheres to soil
to reduce effective
porosity.
Permeability pilot
test ing
'Conventional analysis should include organic content (i.e., BOD. COD, TOC) solids content
iron, manganese, and leachate pH.
-------
XPEG DECHLORINATION
MAKEUP WATER
WATER
VAPOR
CONTAMINATED
SOIL
CLEAN
SOIL
SOURCE: GALSON RESEARCH CORP.
Figurt n. Potasslua Polyethylene Glycol (KKG) Dechlorination
Ttcmwlwr Pucrlntlon
Potassium/polyethylene glycol (KKG) dechlorination is a process useful
for dechlorination of soils contaalnatod at low levels with certain classes of
chlorinated ergaMcs (i.e.. aronatlc bailees). Mhlch Includes KSs. dloxlns.
chlorophenols. and chlorofeonsenes. The dechlorination process includes
excavation of contaminated soil, contacting the soil with the KKG reagent In
a put will or ceaent alxer, removal of the reagent solution, and finally a two
to three cycle rinsing of the treated sell with water in a counter-current
extractor.
The KKC dechlorination process 1s still in (he development stages. It is
currently being tested on dloxln contaminated soils In Gulfport. Mississippi.
-------
014 Sg
Table IS. Technology Summary
Waste Type: Soils
Technology: Potassium/Polyethylene Glycol (KPEG) Dechlorination
Waste cnoracter istics. Data
impacting process collection
feasibility Reason for restriction requirements Reference
Elevated concentrations
of chlorinated organics
Concentrations greater
than 5% require excessive
volianes of reagent (low
ppm is optimum).
Aim lysis for 13
priority
pollutants
Presence of:
- aliphatic organ ics
- inorganics
- metals
Hign moisture content
(greater than 20/.)
Reagent only effective with
aromatic ha 1 ides (PC8s,
dtoxins, chlorophenols,
chlorofcencenes).
Water requires excessive
volumes of reagent.
Analysis for 13
prisrity
pollutants
Soil moisture 13
content
Low pn (pri less tnan 2)
Process operates under
highly alkaline
conditions.
ph testing
13
Presence of alkaline
reactive metals
(e.g., A1)
Uncontrolled reactions
with these metals could
occur under highly
alkaline conditions.
Hetals analysis
13
-------
SOURCE: U. S. ARMY TOXIC AND HAZARDOUS MATERIALS
hGENCY aberceen proving ground
HOT OIL
RESERVOIR
OIL HEATINO
SYSTEM
AIR IN
AIR TO
ATMOSPHERE
AIR CONTAINING
STRIPPED VOC'S
AJ
COMBUSTION AIR
¦ LOWER
AIR
Figure 12. Low Temperature TIwmI Stripping
Technology P««rr1nMnn
Low taaperaturo thonaal stripping i/ttan consist of nixing contaminated
soils In a pug mill or.rotary drum system equipped with haat transfer
surface*. An iiMucee air flow conveys the dosorbed volatile organ1c/a1r
mixture threogn a careen adsorption unit or combust1 on afterburner for the
destruction of the or«an1cs. The air stream is then discharged through a
stock.
Low temperature thermal stripping may he used to remove volatile organic
compounds (Henry's Uw constant > J.S x ig-» atm-aT'/toole) from soils or
startler solids.
-------
014Sg
Table 16. Technology Summary
Waste Type: Soils
Technology: Low Temperature Tnermal Stripping
Waste characteristics
impact ing process
feasibility
Reason for restriction
Data
collection
requirements
Reference
Presence of:
- metals
- inorganics
- nonvolatile organIcs
Presence of mercury (Hg)
Process effective only for
volatile organIcs.
Boiling point of mercury
(356 C) close to operating
temperature for process
(>00 to 300 C).
Analysis for
priority
pollutants
Analysis for
mercury
Unfavorable soil
characteristics
nigh . of clay or silt
Fugitive dust emissions Grain size
during handling.* analysis
- tightly aggregated
soil or hardpan
Incomplete devolatilization
during heating.
Soil sampling
and mapping
- rocKy soii or
glacial till
Rock fragments interfere
with processing.
Soil mapping
- high moisture content
High energy input required.
Dewatertng my bt required
as pretreatment.*
Soil Moisture
content
* See Table 25.
-------
VACUUM PUMP
CARBON
ADSORPTION
MONITORING
WELL
iL
I
0
)l±-
d.
CONDENSER
T
PRODUCTION
WELL
RECOVERY TANK
FUNCTIONAL UNITS OF PILOT VACUUM EXTRACTION SYSTEM
SOURCE:CDM
Figure 13. In-SItu Vacuum Extraction
Technology Pierian on
Vacuum extraction systems consist of a high volume vacuum pump connected
via a ploe system to a network of berahfles or wills drilled In the
contaminated soil zone. Excavation is not required for this system. The
vacuum pulls air through the contaminated soils, stripping volatile organlcs.
The air is subsequently fed through a condenser to recover free product,
and/or through an emissions control system (1.*., a water scrubber or vapor
phase carbon adsorption system).
Vacuum attraction may be hm« to strip volatile organic compounds (Henry's
Law constant > 1.8 x atm-m^/mole) freei sells or porous solids.
-------
Ol-ISg
Tafcle 17- Technology Summary
Waste Type: Soils
Tecnnology: In-Sutu Vacuum Extraction
Waste characteristics Data
impacting process collection
feasibility Reason for restriction requirements Reference
Presence of
- nonvolatile organics
- metals
- cyanides
- inorganics
Only volatile compounds
can be removed (Henry's
Law constant greater than
3 x 10"3 aUMr/nole).
Analysis for
priority pollutants.
Henry's Law
constant, or vapor
pressures for
organics
High solubility of
volatile organics
in water
Dissolved organics are
more mobile and harder
to remove from aqueous
phase.
Contaminant
solubilities
Unfavorai "it soil
characterus
- Low permeability
Hinders movement of air
through soil matrix.
Percolation test,
pilot vapor
extraction tests
Variable soil
conditions
Inconsistent removal rates. Soil mapping
- High huinic content
Inhibition of
volatilization.
Analysis for
organic matter
High moisture content
Hinders movement of air
through so)1.
Analysis of soil
moisture content
Depth to the water
table
Air flow only effective
above water table.
Water table
mapping
-------
Cement-based Inmobilization
Technology Description
Immobilization methods are designed to render contaminants insoluble,
prevent leaching of the contaminants from the solidified soil or sludge,
improve waste handling characteristics, and detoxify the waste.
Equipment required for treatment includes standard cement mixing and
handling equipment end excavation equipment. Because the techniques of cement
mixing and handling are Mell developed, this process can handle many
variations in the soil and sludge composition.
lnmobilization is well suited for solidifying sludges and soils containing
heavy metals, inorganics (generally no more than 20 percent by volume),
asbestos, solidified plastic, resins, and latex.
-------
014Sg
Tade lo. Tecnnology Summary
Waste Type: Soils and Sludges
Technology: Cement-Based Imrobi1ization
Waste characteristics
impacting process
feoSll.il 1 lty
Data
collect ion
Reason for restriction requirements Reference
Organic content should
be no greater than
20-45>; by weight
Organics interfere
with waste materials
bonding.
Analysis for
volatile solids,
total organic
carbon
4.5
Wastes with less than
15X solids
Large volumes of cement
required for immobili-
zation.
Analysis for total
solids
Fine particle size
Insoluble material
passing through a
No. 200 mesh sieve can
delay setting and
curing. Small parti-
cles can also coat
larger particles,
weakening bonds between
particles and cement.
Soil particle
size distribution
Soluble salts of
manganese, tin, zinc,
copper, lead
Reduced physical
strength of final product,
causes large variations in
setting time.
Analysis for
inorganics
4.5
Sodium arsenate,
borate, phosphate,
iodate, sulfide
Retards setting and
curing and weakens
strength of final
product.
Bench-scale
test ing
4.5
Sulfates
Retards setting and
causes swelling and
spalling.
Analysis for
sulfate
4.6
Volatile organics
Volatiles not
effectively
immobilized.
Analysis for
volatile organics,
bench-scale
test ing
Presence of highly'
soluble metals
New stringent
requirements for
leach tests could
make delisting
difficult.
Analysis for
priority
pollutants, bench-
scale testing
4.5
Presence of coal
or lignite
Coals and lignite
can cause problems
with setting, curing,
and permanence of the
end product.
Soil type
distribution
-------
Lime Stab)ligation
Technology Description
Lime siab1112at ion is a process frequently used as a pretreatment step for
sludges cr contaminated soils. Lime serves to-neutralize acids that are
present, and. by raising the pH into the alkaline range (pH 6-10). can
imnobilue heavy metals and reduce leaching. Line stabilization is similar to
cement-based inmobilization in many ways, but is not as permanent as
irnnobi1ization and cannot handle organic* at any level. Lima stabilization is
primarily a pretreatment step used prior to other treatment steps.
-------
014 Sg
Table 19. Technology Summary
Waste Type: Soils and Sludges
Technology: Lime Stabilization
Waste characteristics Data
impacting process collection
feasibility Reason for restriction requirements Reference
Presence of:
- volatile organics
- nonvolatile
organics
- cyanides
Lime used primarily as a
pretreatment step or
interim measure. Lime
only acts to reduce metal
solubilities; it does not
imwbllize organics,
cyanides, or metals.
Analysis for
priority pollutant
Unfavorable soil
Characteristics
variable soil
conditions
Inconsistent stabilization. Soil mapping
5. 6
- low pfenneab'i 1 ity
Variable waste
distnbut ion
Reduction of percolation. Percolation test 5. o
Inconsistent stabilization. Contaminant S. 6
distribution
High leaching or
flushing rate
lime may not immobilize
metals permanently.
Surface hydrology
and precipitation
patterns, bench-
scale test,
leachate testing
-------
TO FILTRATION/
MMMCNTATION
MIXING TANK
MMMM TANK
"igure 14. Chemica* Reouctlon-Oxldatlor
TastmBlBBY ttticrlatun
The cnemical reduction-oxidation (redox) process is emoloyed for the
cntmical transformation of reectants in which tnc oxidation state of one
reactant 1s raised while that of another is lowered. The net result is the
destruction or reduction of the toxicity of hazardous constituents. A
significant use of chemical redox Is the reduction of hexavalent cnromlum to
the less toxic chromium Cr'+.
Chemical redox has limited applications to sludges, oecause other
reoudble components, as well as the material to to reduced, may be attached,
and because of difficulties in achieving intimate contact between the reducing
agent and the hazardous constituent. Chemical reduction 1s used primarily for
aqueous wastes containing
-------
014Sg
Table 20. Technology Summary
Waste Type: Sludges
Technology: Chemical Reduction-Oxidation
Waste characteristics Data
impacting process collection
feasibility Reason for restriction requirements Reference
Organic content
A high organic in the
sludge requires large
•Mounts of oxidation/
reduction reagent.
Analysts for
priority pollutants
Variation in waste
composition
Chemical redox la
indiscriminate;
unwanted side effects
could occur.
Statistical
sampling.
priority pollutant
analysis
1.4
Chromium (*3)
Organic oxidation of
sludges will oxidue
chromium (+3) to the
more toxic and mobile
chromium (+6).
Total chromiun
High viscosity
Subsequent need
for addition of
liquid to aid mixing.
Bench-scale
testing
Low ph of sludge
A low pH (<2) may
interfere with redox
reagents.
pH testing
Oil and grease
content
Oil and grease content of
greater than IX by weight
interferes with reactant/
waste contact.
Analysis for
oil and grease
11
Suspended solids
content
A suspend solids content
of greater than 3X by
weight can interfere with
reductant/waste contact
Inhibiting reduction.
Sludges therefore will
need to be slurried
prior to treatment
(see Table 24).
Total suspended
solids
U
-------
ACIO
STORAGE
PH CONTROLLER
I—1 *
ACIO PCSD PUMP
ALKALI
STORAGE
"T
I
I
I
I
H ~ OH " HjO & SALT
TREATED KMLUKNT
(TO CLARIPIEft IP NECESSARY)
ALKALI PECO PUMP
NEUTRALIZATION TANK
Figure IS. Neutralization
Taehnol—v tftcrlaMan
Neutralization 1s used to change the pH of waste stream. This change is
•ecompHshed through the interaction of an acid (pH 9) with
• waste stream. Acids are used to lower the pH; bases are used to increase
It. The ootlmal range for the final pH is 6.S-9.0.
Changing the pH results In the breaking of emulsions, precipitation of
certain chemical species, and provides control if chemical reaction rates.
The equipment for neutralization consists of a chemical feed and control
system en# a r*p1d ml King process. Sodium hytfrmride. 11m, or sulfuric acid
ore the most eesnon reagents Added to neutral in a wast*. The quantity and
concentration depend en the influent and desired affluent pN.
-------
0145g
Table 21. Technology Summary
Waste Type: Sludges
Technology: Neutralization
Waste cnaractenstics
impacting process
feasibi1lty
Reason for restriction
Oat a
collection
requirements
Reference
High solids content,
high viscosity
Sludge may require
excessive dosages of
chemicals because of the
difficulty of achieving
complete mixing and
contacting. Sludges
containing »3X by weight
suspended solids must be
slurried before treatment.*
Total suspended
solids, viscosity
2, 11
High buffer capacity
potential
Excessive dosage of
neutralizing agent.
Alkalinity
hign heav) iw-tils
concept rat ion
Precipitation of
significant.volume of
heavy metal sludge and
subsequent additional
treatment.
Metals analysis
Sulfuric acid
content (>0.6/;)
If neutralization is
taking place in a
limestone bed, CaS04
produced will coat the
limestone and stop
neutralization.
Sulfuric acid
content
Al*3, Fe*3
concent rat ions
Format ton of hydrox ide
precipitates and cessation
of neutralization.
Metals analysis
* See Table 24.
-------
Composting
technology Descriot ion
Composting involves the storage of high-strength organic sludges and
solids in piles or pits for decomposition, and aerating by periodic
turning. Composting is enhanced by waste size uniformity. Adequate
aerating, optimum temperature, moisture and nutrient contents, and the
presence of the mixed microbial population are necessary to accelerate
decomposition of all organics, phosphorus- and nitrogen-containing
compounds, and oil by hydrolysis or oxidation reactions. Aeration is
accomplished by turning. This is the only biological treatment process
relatively insensitive to toxicants, and it encourages adsorption of
metals. Mesophilic and thermophilic bacteria are active Uien the wfcient
temperature is between 10 C and 45 C or 50 C and 70 C. Alkaline aerooic
conditions are maintained to minimize metal toxicity to microorganisms.
Mfetdls removed by either adsorption or precipitation. The process ii
unsuitable for halogenated aromatic hydrocarbons and refractory organics.
The process can be made environmentally safe by providing means to
iol'ie;t ledchate and runoff water from the coir4>o$ting beds. The protest,
fs not widely used because §n Insufficient market exists for the
resulting end product, humus.
-------
CMsg
Table 22. Technology Summary
Waste Type: Sludges
Techno logy: Compost ing
Wo-.te LOarjicier lit ICS Data
impacting process collection
feasibility Reason for restriction requirements Reference
Variable waste
compos it ion
Inconsistent
biodegradation caused
by variation in
biological activity.
Waste
compos it ion
Water solubility
Contaminants with low
solubility are harder
to biodegrade.
Solubility
Biodegradability
•H-.gh concentration of
toxic contaminants
(metals, complex
organict)
Temperature outsioe
25-70 C range
Nutrient/def iciency
Low biodegradablllty
inhibits process.
High concentrations
may be toxic to
microbes.
Larger, more diverse
microbial population
present in this range.
Lack of adequate
nutrients for bio-
logical activity
(although nutrient
supplements may be
added).
Chemical constit-
uents, presence
of metals/salts,
bench-scale
test ing
Biotoxicity
levels, bench-
scale testing
Temperature
monitoring
C/N/S ratio
6,11
Moisture content
A moisture content
of greater than 79%
affects bacterial
activity and avail-
ability of oxygen.
Ratio of air
to water in
interstices,
porosity of com-
posting mass
6,11
Halogen content
Halogenated organics
are unsuitable for
composting.
Analysis for
total organic
halogen
11
-------
014 Sa
Table 22. (Continued)
Waste Type: Sludges
Tecnnology: Composting
Waste cnorjcter v„t ici
impact ing process
feasibility
Reason for restriction
Data
collection
requirements
Reference
pH outside 4.5-7.5
range
Microbial population
Inhibition of biological
activity.
If indigenous micro-
organisms not present,
cultured strains can be
added.
Sludge pH testing
Culture test
Water and air emissions
and discharges
Potential environmental
and/or health impacts
(control achieved through
air scrubbing, carbon
filtration, forced aeration,
cement liner).
Concentrat ions
of contaminants
Compaction of compost
Particles tend to coalesce
and form an amorpnous mass
that is not easily
maintained in an aerobic
environment (wood chips or
shredded tires may be added
as bulking agents).
Oetermine integrity,
physical nature
of material
Nonuniform particle
Waste mixtures must be of Particle size 11
uniform particle size. distribution
-------
(
Source: FMC Aquifer Remediation Systems
I
Figure 16. In-S1tu Biodegradation
Technology Description
In-situ biodegradation is the process of biodegrading wastes in the soil
using indigenous or Introduced bacterial strains. The process can be
optimized by controlling the dissolved oxygen level, adding nutrients, and
adjusting environmental parameters such as pri and alkalinity.
In-situ biodegradation has been applied to spills of gasoline, fuel oils,
hydrocarbon solvents, nonhalogenated aromatics. alcohols, ketones, ethers, and
glycol.
RECYCLED
GROUND
WATER
Undegraded
Contaminant
Treatment &
Removal
Addition ot
Nutrient &
Oxygen
n nutrient flow
[==j BIOACTIVE
r~l CONTAMINANT
ORIGINAL '
WATER TABLE
-------
C14 c»g
Table 23. Technology Summary
Waste Type: Soils
Technology: In-Situ Biodegradation
Waste L'o'acterlilies
lmpdct'.ng process
feasibility
Reason for restriction
Data
collection
requirements
Reference
Presence of elevated
levels of:
- heavy metals
- highly chlorinated
organics
- some pesticides,
herbicides
- inorganic salts
Can be highly toxic to
microorganisms.
Analysis for
priority pollutant
4. 10
Unt'avora&le soil
characteristics
lo.v oeriiieaui 1 ity
Hinders movement of water Percolation
and nutrients through testing
contaminated area.
4. 10
- variable i.oi 1
conditions
Inconsistent biodegradation
due to variation in
biological activity.
Soil mapping
low soil pH
(less than pH 5.5)
Inhibition of biological
activity.
Soil pH testing
low soil organic
content
Lack of organic substrate
for biological growth.
Soil hunus content
low moisture content
(less than 10ft)
Subsurface biological
growth requires adequate
moisture.
Soil moisture
content
Unfavorable site
hydrology
Groundwater flow patterns
must permit pumping for
extraction and reinject ion.
Site hydrogeology
must be well
defined
4. 10
Unfavorable groundwater
quality parameters
- low aissolved oxygen
Oxygen necessary for
biological growth.
Dissolved oxygen
in ground water
4. 10
low pn. alkalinity
Inhibition of
biological activity.
pH and alkal inity
of ground water
4. 10
-------
014'q
Table 24 Pretreatment Methods
Sludge
PrOL. lem
Treatment/Solution
Material transport Dragline
and excavat ion
Crane-operated excavator bucket to dredge
or scrape sludge from lagoons, ponds, or
pits.
Excessive water
content
Backhoes,
excavators
Hudcat
Positive
displacement pump
(e.g., cement pump)
Mo/no pump
Evaporator
Filter press
Belt filter
Useful for subsurface excavation at the
original ground level.
A bulldozer or loader muck like a crawler
capable of moving through sludge.
This punp can handle high density sludges
containing abrasives such as sand and
gravel.
A progressing cavity pump that can pump
high viscosity sludges.
Excess water can be evaporated from sludge.
The Carver-Greenfield process is a
potentially applicable technology. The
sludge is mixed with oil to form a slurry
and the moisture is evaporated through a
multiple-effect evapof-ator.
Sludge is pumped into cavities formed by a
series of plates covered by a filter
cloth. The liquid seeps through the
filter cloth, and the sludge solids remain.
Sludge drops onto a perforated belt, where
gravity drainage takes place. The
thickened sludge is pressed between a
series of rollers to produce a dry cake.
Vacuum f iIter
- Sludge is fed onto a rotating perforated
drum with an internal vacuum, which
extracts liquid phase.
-------
0X4Sg
Table 24. (continued)
Sludge
Problem Treatment/Solution
Excessive water
content (continued)
Centrifuge
(solid bowl)
Drying
Gravity thickening
- Sludge feeds through a central pipe that
sprays sludge into the rotating bowl.
Centrate escapes out the large end of the
bowl, and the solids are removed from the
tapered end of the bowl by means of a
screw conveyer.
- Rotary drying, flash drying, sand ted.
- Slurry enters thickener and settles into
circular tank. The sludge thickens and
compacts at the bottom of the tank, and
the sludge blanket remains to help further
concentration.
Excessive sludge Slurry
v 1 scot-it >
- Addition of water or solvent.
Extreme pH
Neutralization ->• Lime is a widely used alkaline material
for neutralizing acid wastes, and sulfuric
acid is used to neutralize alkaline wastes.
Oversize material
removal, disaggre-
gation, sorting
See Table 25
(Soils)
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014 tg
Table 25. Pretreatment Methods
Soi Is
Treatment/Soliit ion
?! Oi iem
Mater id 1 transport Dragline
and excavation
Backhoe
Heavy earth
moving equipment
Conveyers
Oversize material Vibrating screen
removal. disaggre-
gation. sorting
Static screen
Grizzlies
Hamner mill
- Crane-operated excavator bucket to scrape
or dredge soil to depths and farther
reaches.
- Useful for subsurface excavation or at the
original ground level.
- Includes bulldozers, excavators, dumptrucks
for excavation and transport.
- May be useful for large volume transport
or feed to treatment unit.
- Vibrates for screening of fine particles
from dry materials. There is a large
capacity per area of screen, and high
efficiency. Can be clogged by very wet
material.
- A wedge bar screen consists of parallel
bars that are frame-mounted on accrued
deck. A slurry flows down through the
feed inlet and flows tangentially down the
surface of the screen. The curved
surfaces of the screen and the velocity of
the slurry provide a centrifugal force
that separates small particles.
- Grizzlies are parallel bars that are frame-
mounted at an angle to promote materials
flow and separation. Grizzlies are used
to remove a small amount of oversized
material from predominantly fines.
- Used to reduce particle size of softer
materials.
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OI45g
Table 25. (continued)
Soils
Problem
Treatment/Solution
Impact crushers
Fugitive Missions
Dewatering
Dust suppressant
Negative pressure
air systems
Belt filter press,
centrifuge
Break up feed particles by impact with
rotating hammers or bars. Impact crushing
writs best with material that has several
planes of weakness, such as impurities or
cracks.
Natural (e.g., water) or synthetic
materials that strengthen bonds between,
soil particles.
Vacuu* systems may be used to collect
vapors and or dust particles and prevent
release into atmosphere.
' Useful for dewatering of very wet soils
(lagoon sediments, wetlands).
Rotating dryer
- Additional drying may permit higher feed
rates for thermal treatment systems.
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