P/EPA
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati OH 45268
EPA/625/4-89/021
September 1989
Technology Transfer
Seminar Publication
Solvent Waste Reduction
Alternatives
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EPA/625/4-89/021
September 1989
Seminar Publication
Solvent Waste Reduction Alternatives
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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Disclaimer
This document has been reviewed in accordance with U.S. Environmental Protection
Agency policy and approved for publication. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
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Contents
Tables vi
Figures vii
Acknowledgments viii
Chapter 1 Land and Liquid Disposal Bans 1
Introduction 1
Treatment Standards (Section 268.40) 2
Variances and Extensions '. 4
Treatment in Surface Impoundment Exemption (Section 268.4) 5
Prohibition on Dilution (Section 268.3) . . . 6
Storage Prohibition (Section 268.50) 6
Permit Program 7
Testing and Recordkeeping (Section 268.7) 7
Treatment Standards for Solvents (Section 268.41) 8
Treatment Standards for Dioxins (Section 268.41) 10
Information Requirements 10
Chapter 2 Title III SARA - The Community's Right to Know 13
Introduction 13
An Overview of Title III 13
Emergency Notification - Section 304 13
Community Right-to-Know Reporting Requirements - Sections 311 - 312 14
Toxic Chemical Release Reporting - Section 313 15
Conclusions 16
Chapter 3 Solvent Waste Burning Regulations 17
Chapter 4 Waste Minimization Liability Issues 19
Introduction 19
HSWA - Waste Treatment and Minimization Requirements 19
Complying with Waste Treatment and Minimization Requirements:
Generation Options and the "Liability Hierarchy" 23
References 27
Chapter 5 Minimization of Process Equipment Cleaning Waste 31
Why Equipment is Cleaned 31
Reduction of Cleaning Frequency 32
Inhibition of Fouling 32
Reduction of Quantity and Toxicity of Cleanup Waste 33
Cost of Cleaning 36
Summary 36
References 37
HI
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Contents (continued)
Chapter 6 Source Reduction - Parts Cleaning 39
Introduction 39
Industry Response to Reduce Solvents Usage 39
Cleaning Concept 39
Resolution 40
Summary 45
Chapter 7 Solvent Waste Minimization by the Coatings Industry 47
Functions of Coatings 47
Coating Formulation 48
Solvent Reduction 48
Recent Advances 49
Chapter 8 What to do with Hazardous Waste: Regulations, Management, and Disposal 51
Introduction 51
Priority Pollutants 52
Chemical Feedstock Procurement and Usage 54
Assessing Data for Objective Control Strategies 55
Summary 65
References 68
Chapter 9 Waste Reduction for Chlorinated Solvents Users 69
Waste Reduction: Background 69
Trends in Chlorinated Solvents Use 70
Recycling Through Contract Reclamation 70
Recycling Through In-House Reclamation 70
Waste Reduction: Customer Assistance 73
Factors Influencing Solvent Consumption 74
Waste Disposal Issues 77
Conclusion: The Benefits of Waste Reduction 77
Appendix A 78
Appendix B 79
Appendix C 80
Chapter 10 On-Site Reuse and Recycle of Solvents 81
Introduction 81
Types of Solvents Used 81
Generation and Properties of Used Solvents 82
Options for Reuse and Recycling 83
Hazardous Waste Reduction Practices and Examples 86
Conclusions 90
Chapter 11 Commercial (Off-Site) Solvent Reclamation 93
Introduction 93
Types of Recycling 94
Reclamation Technology 95
Quality Control 97
Recycling Capacity 97
Selecting a Recycling Facility 98
IV
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Contents (continued)
Chapter 12 Making the Most of Bottoms and Residuals
101
Chapter 13 Treatment: Solvent Wastestreams 105
Introduction ^c
Description of Solvents Used by Various Industries . 105
Commercially Available Treatment Technologies '.'.'.'.'.'.'.'.'.'. 106
Conclusions 10o
Chapter 14 Treatment of Spent Solvent Wastewaters: Focus on Changing Economics ....... 109
Introduction ^ ng
Steam Stripping '.'.'.'.'. 109
Carbon Adsorption '.'.'.'.'.'.'. no
Biological Treatment '.'.'.'.'.'.'.]'.'.'.'"''' 111
Cost Optimization Example '.'.'.'.'.'.'. 111
Conclusions 112
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Tables
No.
Page
1-1. Schedule for Land Disposal Prohibitions 1
1 -2. Solvent Treatment Standards
Table CCWE 9
1-3. Dioxin Treatment StandardsTable CCWE 10
2-1. Selected Key Dates for Reporting Under Title III 14
2-2. Summary of Chemical Lists for Title III 15
5-1. Typical Routes and Origins of Deposit Formation in Process Equipment 32
5-2. Some Chemical Cleaning Compounds and their Usage 34
5-3. Relative Heat Exchanger Costs 36
7-1. EPA Guidelines for Maximum Volatile Organic Content of Coatings 49
7-2. Consequences of Improved Solids and Transfer Efficiency 50
8-1. Regulatory Standards Addressing Usage and Control of
Commonly Used Solvents 53
8-2. Mobility Characteristics of Organic Compounds 54
8-3. Proposed Toxicity Characteristic Contaminants and Regulatory Levels 55
8-4. Chemical Feedstock Characteristics 55
8-5. Off-site Disposal Guidelines 57
8-6. Precipitation Reactions 58
8-7. Typical Properties and Content of Metal Hydroxide Sludges . 60
9-1. Contract Reclamation 70
10-1. Properties of Used and Recycled Mineral Spirits 83
10-2. Waste Audit Outline 86
10-3. Standard Waste Audit Format - Automotive Repairs 86
10-4. Summary of Segregation Recommendations for
Reclamation and Disposal of Solvents 88
10-5. Suppliers of Solvent Recycling Equipment Suitable for
On-Site Reclamation - Single-plate Packaged Stills 89
10-6. Suppliers of Solvent Recycling Equipment Suitable for On-Site
Reclamation - Custom Builders of Fractional Distillation Units 91
10-7. Suppliers of Solvent Recycling Equipment Suitable for
On-Site Reclamation - Thin-film Evaporation 91
14-1. Cost Optimization Summary 112
VI
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Figures
No.
Page
5-1. Waste minimization of equipment cleaning waste: summary of approaches 36
8-1. Technical approach to reviewing material balances in
waste reduction audits 56
8-2. Waste management strategies having application to wastewaters. '..'...' 59
8-3. Waste management strategies applicable to metal hydroxide sludges. ; 61
8-4. Percent total solids as function of treatment 63
8-5. Residual volatile organics as function of treatment 63
8-6. An overall strategy applicable to the control management of
solvent-laden residues 64
8-7. Waste management practices applicable, to
solvent-laden residue 65
8-8. Waste management strategies for solvent-laden residue. 66
8-9. Strategies applicable to solid by-products of drying operations. ....'. . 66
8-10. Control management strategies for packaged laboratory chemicals. , 67
8-11. Control management strategies for containers of waste solvent. . 67
8-12. Management strategies applicable to residues categorized as
waste oils and oily residues 68
9-1. WRAP flow chart '. ., . 69
9-2. Applications/end uses for specialty chlorinated solvents 71
9-3. U.S. demand for chlorinated solvents 72
9-4. Hazardous waste disposition flow chart 74
10r1. Plots of solvent volumes vs. payback period (years) for
solvents of different costs 85
12-.1. Acid-clay process 102
12-2. Distillation clay process 103
12-3. Solvent recycling 104
VII
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Acknowledgments
This seminar publication is based wholly on edited versions of presentations made at
U.S. Environmental Protection Agency (EPA) Technology Transfer Seminars titled
"Solvent Waste Reduction Alternatives." These seminars were held in Atlanta, GA
(February 23-24, 1988); Boston, MA (March 3-4, 1988); Seattle, WA (March 16-17,
1988); Chicago, IL (April 7-8, 1988); and Kansas City, MO (April 26-27, 1988).
Guidance in the preparation of this publication was provided by Norman Kulujian and
Denis Lussier, U.S. EPA, CERI, Cincinnati, OH; and Jim Berlow, U.S. EPA, Technology
Waste Treatment Branch, Washington, DC. Editorial and review assistance was
provided by Chuck Marshall and Sheree Gold, JACA Corp., Fort Washington, PA.
Appreciation for peer review is expressed to Sherryl Livingston, MN Pollution Control
Agency, Hazardous Waste Division; Janet Bearden, OTS; David Stephan, PhD, RREL;
Dwight Hlustick and Robert Holloway, OSW; and Justice Manning, CERI; all of EPA.
VIII
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Chapter 1
Land and Liquid Disposal Bans
Stephen Weil
Mitch Kidwell
U.S. Environmental Protection Agency
Office of Solid Waste
Land Disposal Restrictions Branch
Washington, DC 20460
Introduction
The Hazardous and Solid Waste Amendments
(HSWA) to the Resource Conservation and Recovery
Act (RCRA) were enacted on November 8, 1984.
Among other things, these far-reaching amendments
require EPA to evaluate all hazardous wastes
according to a strict schedule to determine whether
land disposal of these wastes is protective of human
health and the environment. For wastes that are
restricted from land disposal, the amendments require
EPA to set levels or methods of treatment which
substantially diminish a waste's toxicity or reduce the
likelihood that a waste's hazardous constituents will
migrate. Beyond specified dates, restricted wastes
which do not meet the treatment standards (or are
otherwise exempt as discussed in this chapter) are
prohibited from land disposal (see Table 1-1).
According to HSWA, if EPA fails to set treatment
standards for a particular waste by specified
deadlines, that waste is automatically prohibited from
land disposal. These so-called "hammer provisions"
provide the impetus for EPA to keep to the strict
schedule.
On November 7, 1986, EPA promulgated the first
phase of the land disposal restrictions (51 FR 40638
[codified at 40CFR268.2(a)]). In.the November 7,
1986, final rule, EPA established the framework for
implementing the land disposal restrictions program.
EPA also established specific treatment standards and
effective dates for the first category of wastes subject
to the restrictions, F001-F005 spent solvent wastes,
and F020-F023 and F026-F028 dioxin-containing
wastes. This chapter summarizes the November 7,
1986, rulemaking and describes the key regulatory
requirements pertaining to treatment standards,
variances, and extensions. The booklet also outlines
the new responsibilities of generators, treatment
facilities, and disposal facilities under the rule. Finally^
Table 1-1. Schedule for Land Disposal Prohibitions
November 8, 1986
JulyS, 1987
Augusts, 1988
Novembers, 1988
June 8, 1989
May 8, 1990
Within 6 months of
listing /identification
(these wastes are not
subject to the
automatic land disposal
prohibition)
Dioxin-containing wastes (F020, F021,
F022, F023, F026, F027, F028)
Spent solvents (F001, F002, F003, F004,
F005)
California list wastes (Liquid hazardous
wastes containing: free cyanides, PCBs,
and certain metals at or above specified
concentration levels, and those liquid
hazardous wastes having a pH of less than
or equal to 2.0. Also, both liquid and non-
liquid hazardous wastes containing
halogenated organic compounds at or
above specified concentration levels.)
At least one-third of all listed hazardous
wastes
Wastes disposed of in injection wells
Contaminated soil and debris from
CERCLA Section 104 or 106 response
actions and RCRA corrective actions
At least two-thirds of all listed hazardous
wastes
All remaining listed hazardous wastes
All characteristic listed hazardous wastes
Newly listed wastes
it provides an overview of the specific treatment
standards for solvent- and dioxin-containing wastes,
the first wastes that EPA has evaluated for the land
disposal restrictions. The booklet is geared to
individuals who are familiar with EPA's hazardous
waste regulatory program. While it presents a
summary of the land disposal restrictions program, it
is not intended to be a comprehensive review of all
regulatory issues associated with the November 7
rulemaking. For further information, contact the
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RCRA/Superfund Hotline at (800) 424-9346 (toll free)
or (202) 382-3000 in the Washington, DC,
metropolitan area.
In the final rule, EPA defined land disposal to include,
but not limited to, any placement of hazardous waste
in:
Landfills.
Surface impoundments.
* Waste piles.
Injection wells.
Land treatment facilities.
Salt domes or salt bed formations.
Underground mines or caves.
Concrete vaults or bunkers.
The land disposal restrictions rule covers hazardous
wastes placed in land disposal units after the effective
dates of the prohibitions. Wastes disposed of before
November 7, 1986, do not have to be removed from
land disposal for treatment. However, if wastes are
removed from land disposal, the wastes must meet
the applicable treatment standards before subsequent
new placement in or on the land, or they must be the
subject of a variance or extension as discussed in this
booklet. Contaminated soil and debris from the
Comprehensive Environmental Response, Compen-
sation, and Liability Act of 1980 (CERCLA) Section
104 and 106 response actions and RCRA corrective
actions became subject to the land disposal
restrictions rule on November 8, 1988. In addition,
wastes disposed of in underground injection wells
became subject to the land disposal restrictions on
August 8, 1988.
Wastes which were placed into storage prior to the
effective date are not subject to the restrictions on
storage. However, once taken out of storage, these
wastes must meet the applicable treatment standards
prior to land disposal, or they must be the subject of a
variance or extension as discussed in this booklet.
Wastes may he treated in surface impoundments that
meet minimum technological requirements provided
that (among other things discussed in this booklet)
treatment residuals which do not meet the treatment
standards are removed within one year of placement
of the waste in the impoundment.
Both interim status and permitted facilities are subject
to the land disposal restrictions rule; these restrictions
supersede 40 CFR 270.4(a), which currently provides
that compliance with a RCRA permit constitutes
compliance with Subtitle C). However, small quantity
generators of less than 100 kg/month of hazardous
waste (or less than 1 kg/month of acute hazardous
waste) are not subject to the restrictions.
The November 7, 1986, final rule outlines the
Agency's approach to implementing the
congressionally mandated restrictions on land disposal
of hazardous waste. The rule includes:
Procedures for setting treatment standards.
Procedures for obtaining variances from the
treatment standards.
Procedures for granting nationwide variances from
the effective dates of the land disposal restrictions
due to insufficient alternative treatment capacity.
Procedures for obtaining extensions to the
effective dates of the land disposal restrictions on
a case-by-case basis.
Procedures for petitioning to obtain a variance
from the land disposal restrictions based on a
finding that there will be no migration of hazardous
constituents from the disposal unit or injection
zone for as long as the wastes remain hazardous.
Provisions for allowing restricted wastes to he
treated in surface impoundments.
Provisions for prohibiting dilution as a substitute
for adequate treatment to achieve the treatment
standards.
Provisions for tabulating the storage of restricted
hazardous wastes.
Provisions for modifying permits.
Requirements for testing and recordkeeping.
Specific treatment standards for certain dioxin-
and spent solvent-containing wastes.
Treatment Standards (Section 268.40)
HSWA prohibits land disposal of restricted wastes
unless EPA determines that continued land disposal is
protective of human health and the environment, or
unless the applicable treatment standards have been
met. HSWA requires EPA to set levels or methods of
treatment which substantially diminish the toxicity of a
waste or substantially reduce the likelihood that
hazardous constituents will migrate from a waste.
These levels or methods, referred to as treatment
standards, must minimize short- and long-term threats
to human health and the environment. After the
effective dates of the prohibitions, hazardous wastes
that do not comply with the treatment standards are
prohibited from being placed in land disposal units
unless:
EPA has approved a petition demonstrating that
hazardous constituents will not migrate from the
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land disposal unit for as long as the wastes
remain hazardous.
EPA has granted an extension to the effective
date of the prohibition.
How Are the Treatment Standards Established?
To establish treatment standards, EPA identifies
wastes with similar characteristics (i.e., similar
physical and chemical properties). EPA then
categorizes these similar wastes into broad "waste
treatability groups" and subgroups. The treatability
groups take into account differences in the types and
effectiveness of treatment for those particular wastes.
Treatability groups may be formed by grouping wastes
by industries or manufacturing processes which
generate wastes with similar treatability characteristics
EPA then evaluates identified technologies used to
treat the wastes to determine the best demonstrated
available technology (BOAT) for each waste
treatability group.
What Is the Best Demonstrated Available
Technology (BOAT)?
BOAT is the best available method of treatment
demonstrated to be achievable for each waste
treatability group. To establish BOAT for a particular
waste treatability group, EPA first collects and
analyzes data on existing treatment technologies for
that waste group that are demonstrated by full-scale
operation. EPA will not consider pilot- and bench-scale
operations in identifying "demonstrated" treatment
technologies.
Once EPA has identified "demonstrated"
technologies, 'the Agency then determines whether
these technologies may be considered "available,"
based on three criteria:
The technology must be commercially available.
The technology must present less risk to human
health and the environment than land disposal of
the untreated waste.
The technology must provide substantial
treatment.
Technologies considered in setting BOAT must be
found to be commercially available (i.e., either the
technology itself, or the services of the technology,
may be purchased). A proprietary or patented
treatment technology must be able to be purchased
from the proprietor. If it cannot be purchased, the
technology is considered unavailable and the
treatment standard will be based on the next best
technology that is available.
EPA then compares the risks to human health and the
environment associated with treatment of the wastes
by the demonstrated technologies to the risks
associated with the land disposal of untreated wastes.
Based on this comparative risk assessment, those
treatment technologies that present greater risks than
land disposal of the untreated wastes will be
considered unavailable and will be excluded as a basis
for establishing treatment standards.
If all demonstrated treatment technologies present
greater risks than land disposal for a particular waste,
EPA will not set a treatment standard for that waste.
Therefore, the restricted waste will be prohibited from
land disposal (unless it is the subject of an approved
"no migration" petition) until a new or improved
technology emerges that does not pose a greater risk
than land disposal.
EPA will not consider treatment technologies that are
prohibited under RCRA Section 3004(n) because of
the potential for air emissions of hazardous
constituents as available for purposes of establishing
treatment standards.
Also, to be considered an available technology, the
technology must provide substantial treatment, that is,
it must substantially diminish the toxicity of the waste
or reduce the likelihood of migration of the waste's
hazardous constituents. This excludes technologies
that would provide treatment only for the sake of
treatment without providing substantial reduction in
risk to human health and the environment.
Once the demonstrated available treatment
technologies are identified, EPA then evaluates
performance data on these technologies to determine
if the data are representative of well-designed and
well-operated systems. Only data from well-designed
and well-operated systems will be considered in
setting BOAT. These performance data are then
analyzed to determine the best demonstrated available
technology.
When treatment data are available for several different
technologies, EPA uses a statistical method known as
analysis of variance to determine the level of
performance that represents BOAT. EPA also uses a
process variability factor in setting BOAT which
considers normal variability in well-designed and well-
operated treatment processes.
Setting the Treatment Standards
Once BOAT is identified, EPA establishes the
treatment standards as either a specific technology (or
group of technologies) or as a performance level (i.e.,
the concentration level of hazardous constituents in a
waste or extract of the waste that is representative of
treatment by BOAT; for the November 7, 1986 rule
covering solvents and dioxins, this is expressed as a
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concentration level of hazardous constituents in an
extract of the waste developed by using the Toxicity
Characteristic Leaching Procedure [TCLP]). Wherever
possible, EPA attempts to set concentration-based
performance standards since they provide the most
flexibility to the regulated community. Treatment
technologies that are not used in setting treatment
standards may still be used to comply with treatment
standards expressed as performance levels.
What Is the TCLP?
The TCLP is an analytical method used to determine
whether the concentrations of hazardous constituents
in a waste extract or an extract of the treatment
residual meet the applicable treatment standards. EPA
promulgated the TCLP for use only in the solvents
and dioxins final rule, and only when treatment
standards are expressed as concentration levels of
hazardous constituents in an extract. As new
developments occur, EPA will revise the TCLP with
due consideration of public comments, including those
received on the June 13, 1986, Organic Toxicity
Characteristic proposed rule (51 FR 21648).
Variances and Extensions
Under certain conditions, EPA may grant a variance
from treatment standard, an extension to the effective
date of the land disposal prohibition, or an exemption
from the prohibition for a specific waste at a specific
site. In the November 7, 1986 rulemaking, EPA
established four types of variances and extensions:
Variance from the treatment standard.
Two-year national capacity variance.
Case-by-case extension.
"No migration" petition.
Variance from the Treatment Standard (Section
268,44)
EPA established the variance from the treatment
standard to account for wastes that are significantly
different from the wastes evaluated by EPA in setting
treatment standards and, therefore, cannot be treated
to meet the applicable treatment standard; for
example, exotic wastes, wastes formed by inadvertent
mixing, and wastes that require the use of
technologies different from those used to set the
treatment standard. If a petitioner can successfully
demonstrate that a waste is significantly different from
the wastes in its treatability group such that it cannot
meet the treatment standard, EPA will grant a
variance from the treatment standard for that
particular waste. In granting a variance, EPA will
establish a new treatability group for that waste (and
all similar wastes) and set a new treatment standard.
For EPA to grant a variance, the petitioner must not
only successfully demonstrate that the waste is
significantly different from the wastes evaluated by
EPA in setting the treatment standards, but also
demonstrate that treatment of the waste cannot meet
the treatment standard. The petitioner must show (by
actual treatment attempts that fail, or by extensive
analyses of the waste) that treatment of the waste by
well-designed and well-operated technologies is
unsuccessful in meeting the specified levels, or that
the waste cannot be treated by the specified
technology.
Anyone submitting a petition for a variance from the
treatment standard must certify that all information in
the petition (see page 10) is true, accurate, and
complete. In addition, they must comply with all
applicable hazardous waste management regulations
during the petition evaluation process.
In considering variance petitions, EPA first will
compare the physical and chemical characteristics of
the petitioner's waste with the physical and chemical
characteristics of the wastes evaluated by the Agency
in setting the treatment standard. This comparison will
enable EPA to reexamine its treatment standard for
the waste. EPA will then determine whether the
petitioner's treatment system (if any) is well designed
and well operated, and whether the system reflects
treatment by BOAT (although the restricted wastes
are not required to be treated by BOAT).
Two-Year National Capacity Variance (Section
268.30)
Certain wastes may continue to be land disposed
without treatment for up to two years past the
statutory effective dates of the restrictions rule if EPA
determines that adequate treatment capacity is not
available on a nationwide basis. In determining the
need for a national capacity variance, EPA will
consider, on a nationwide basis, both the capacity of
alternative treatment technologies and the quantity of
restricted waste generated. If sufficient waste
treatment capacity is available, the restriction on land
disposal of that waste goes into effect on the statutory
deadline. If there is a significant shortage of national
capacity to treat all the restricted waste, EPA may set
an alternative effective date based on the earliest date
on which adequate treatment capacity becomes
available.
In determining available capacity, EPA will consider
both permitted and interim status on-line facilities.
EPA will also consider planned facilities and capacity
extensions that will be on-line by the effective date of
a land disposal prohibition. On line facilities will
include on-site and off-site facilities, as well as
stationary and mobile facilities. EPA will not consider
underground injection in its capacity determinations
until the Agency has determined whether such
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injection is fully protective of human health and the
environment
EPA will compare available treatment capacity
nationwide to the quantities of the restricted waste
generated annually nationwide. Available capacity will
include:
Commercially available capacity.
Private facility capacity which can be used to
manage additional waste generated by that facility.
Private facility capacity which can be used to
manage wastes generated by other facilities (i.e.,
can act as a commercial facility).
Case-by-Case Extensions (Section 268.5)
In cases where alternative treatment of disposal
capacity cannot reasonably be made available by the
effective date of the land disposal prohibitions,
interested parties may petition EPA for an extension of
the effective date on a case-by-case basis. EPA may
grant a case-by-case extension of up to one year.
This extension is renewable only once.
To be considered for a case-by-case extension, a
petitioner must demonstrate a good faith effort to
locate and contract with hazardous waste treatment,
recovery, or disposal facilities nationwide to manage
the waste. A petitioner must also demonstrate that he
has entered into a binding contract to construct or
otherwise provide adequate treatment, recovery, or
disposal capacity sufficient to manage the entire
volume of wastes. In addition, a petitioner must
demonstrate that, due to circumstances beyond his
control, alternative treatment, recovery, or disposal
capacity cannot reasonably be made available by the
effective date.
Anyone submitting a petition for a case-by-case
extension must certify that all information in the
petition (see page 10) is true, accurate, and complete.
In addition, they must comply with all applicable
hazardous waste management regulations during the
petition evaluation process.
If wastes that receive an extension to the effective
date (either a 2-year national variance or a case-by-
case extension) are to be placed in or on the land,
then they must be placed in a facility that is in
compliance with the minimum technological
requirements. These requirements, including a double
liner, leachate collection system, and ground-water
monitoring system, apply to new units, replacement
units, or lateral expansions of existing landfills or
surface impoundments at existing facilities. Wastes
receiving an extension may also be placed in such
facilities that meet other alternative operating
practices, design features, or siting characteristics
determined by the EPA Administrator to be equally
protective of human health and the environment.
"No Migration" Petitions (Section 268.6)
EPA will consider allowing land disposal of restricted
wastes if a petitioner can demonstrate, to a
reasonable degree of certainty, that such disposal will
not allow migration of hazardous constituents from the
disposal unit or injection zone for as long as the
wastes remain hazardous. In general, a successful
"no migration" petition (see page 11 for petition
requirements) will allow only land disposal of a
specific waste at a specific unit.
EPA believes that there will be very few instances
when "no migration" demonstrations can be
successfully made. However, candidates for a
successful petition include cases where wastes
containing relatively immobile hazardous constituents
are placed in monofills located in arid climates with no
ground-water recharge. Other candidates for "no
migration" petitions are cases where a small amount
of compatible waste is placed in a massive and stable
geological formation such as a salt dome.
Rulemaking Procedures
All variances and extensions are rulemaking
procedures. Variances from the treatment standard,
case-by-case extensions, and "no migration"
exemptions are petition processes (the two-year
national capacity variance is solely an EPA
determination). EPA will publish its tentative
determination on a petition in the Federal Register.
After a 30-day comment period, EPA will publish its
final decision in the Federal Register.
Treatment in Surface Impoundment
Exemption (Section 268.4)
EPA will allow hazardous wastes to be treated in
surface impoundments under the following conditions:
Treatment residuals not meeting the treatment
standards can remain in a surface impoundment
for up to one year. Beyond that time period, the
' treatment residuals that do not meet the treatment
standards must be removed and treated to meet
the treatment standards before being disposed,
and may not be placed into another surface
impoundment (treatment residuals that do meet
the treatment standards may remain in the surface
impoundment). In cases where the volume of
liquid wastes annually flowing through an
impoundment (or series of impoundments) is
greater than the capacity of the impoundment, this
flow-through may constitute annual removal of the
supernatant for the purposes of this requirement
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(this will not, however, constitute removal of any
sludge residues requiring annual removal).
* The surface impoundment must meet minimum
technological requirements including a double
liner, leachate collection system, and ground-
water monitoring system, or
The surface impoundment must meet other
alternative operating practices, design features, or
siting characteristics determined by the EPA
Administrator to be equally protective of human
health and the environment.
A surface impoundment may receive a waiver from
the double liner and leachate collection system
requirements if EPA determines that it meets certain
other conditions, including:
It has at least one liner that is not leaking; it is
located more than one-quarter mile from an
underground drinking water source; and it is in
compliance with the applicable ground-water
monitoring requirements of RCRA Section 3005.
or
It is located, designed, and operated so as to
ensure that no hazardous constituents will migrate
to ground water or surface water in the future.
Owners or operators seeking an exemption for
treatment in surface impoundments must certify to the
EPA Regional Administrator that the impoundment
meets the minimum technological requirements (or is
exempt as discussed above) and must submit a copy
of the facility's waste analysis plan.
Prohibition on Dilution (Section 268.3)
The land disposal restrictions rule prohibits the dilution
of restricted wastes as a substitute for adequate
treatment to meet the treatment standards. This
provision ensures that no individual circumvents the
intent of EPA's concentration-based regulations by
simply adding material to wastes that do not meet the
treatment standards, rather than treating the wastes.
Dilution as a necessary part of the waste treatment
process is allowed under the final rule. For example,
the addition of an acidic or basic reagent to a waste in
a neutralization pond does not merely dilute the waste
into a larger volume of waste; rather, the addition of
the reagent is a necessary part of the process of
chemically altering the waste so as to render it less
hazardous.
Storage Prohibition (Section 268.50)
Under the land disposal restrictions rule, storage of
restricted wastes is prohibited except where storage is
solely for the purpose of accumulating sufficient
quantities of wastes to facilitate proper treatment,
recovery, or disposal. Treatment, storage, and
disposal facilities may store restricted wastes for as
long as needed, provided that such storage is solely
for this purpose. However, if the facility stores a
restricted waste for more than one year, it bears the
burden of proof, in the event of an enforcement
action, that the storage was solely for this purpose
(there is no notification requirement for storage of
more than one year). For storage of less than one
year, EPA bears the burden of proof that such storage
was not for the sole purpose of accumulating
sufficient quantities of wastes to facilitate proper
treatment, recovery, or disposal. This prohibition on
storage does not apply to wastes which meet the
treatment standard, wastes which have been granted
an extension to the effective date, and wastes which
are the subject of a "no migration" exemption.
For generators without a RCRA permit or interim
status, the rules governing storage (Section 262.34)
have not changed under the land disposal restrictions
rule. Large quantity generators may store restricted
hazardous wastes on-site for 90 days or less without a
permit or interim status. Small quantity generators of
100 to 1,000 kg of hazardous wastes per month may
accumulate wastes for up to 180 days, or 270 days if
the waste must be transported 200 miles or more to a
treatment, storage, or disposal facility. (The EPA
Regional Administrator may grant a 30-day extension
to these storage limits on a case-by-case basis.) The
land disposal restrictions now impose the additional
requirement that such storage must be solely for the
purpose of accumulating sufficient quantities of waste
to facilitate proper treatment, recovery, or disposal.
As prior to the land disposal restrictions, all generator
storage must comply with the applicable standards of
RCRA Part 265, including contingency planning,
preparedness and prevention, and personnel training.
In addition, generators must store their wastes in
containers or tanks that are clearly marked with the
words "Hazardous Waste" and with the date on which
the tanks or containers enter storage. All container
markings must be clearly visible for inspection.
If compliance with the land disposal restrictions
requires storage beyond 90 days (or 180 days for
small quantity generator waste), generators must
obtain RCRA interim status or a RCRA permit For a
generator to qualify for interim status, the wastes must
have been placed into storage in tanks or containers
before the effective date of the restrictions. A
generator must also demonstrate that the additional
storage time is necessary to comply with the land
disposal restrictions. Generators who need to obtain
interim status must submit a Part A application to EPA
by the earlier of two deadlines:
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Six months after publication of regulations which
first require the facility to comply with RCRA Part
265.
Thirty days after the date the facility first becomes
subject to the Part 265 standards. This is the
most likely deadline for most generators since a
generator first becomes subject to the permitting
requirements when the accumulation time limit is
exceeded.
Interim status granted under these conditions will
apply only to those restricted wastes identified in the
Part A application.
Generators who obtain interim status are subject to
the applicable RCRA Part 265 standards. EPA can
take corrective action against these generators
pursuant to Section 3008(h) for failure to comply with
these standards. EPA can also require the generator
to submit a Part B permit application.
The rules governing storage at transfer facilities
(Section 263.12) have not changed under the land
disposal restrictions. Transporters may store restricted
wastes at a transfer facility for up to 10 days without a
permit or interim status.
Permit Program
Interim Status Facilities
Under RCRA, treatment facilities operating under
interim status may make certain changes to their
operations which enable them to handle new wastes.
These changes include:
Accepting new wastes.
Increasing design capacity (if the facilities can
demonstrate to EPA that there is a lack of
available capacity).
Changing treatment, storage or disposal
processes as necessary to comply with state or
local laws.
To accept new wastes, interim status facilities must
revise their Part A permit applications. To increase the
design capacity or change a treatment, storage, or
disposal process, an interim status facility must obtain
prior approval from EPA. RCRA limits these changes
to facility alterations and expansions that do not
exceed 50 percent of the capital cost of a comparable
new facility.
In a notice published in the Federal Register on
December 11, 1986, EPA proposed to give interim
status treatment and storage facilities more flexibility
in managing wastes restricted from land disposal. EPA
proposed to allow these interim status facilities to
expand their operations by more than 50 percent in
order to treat or store restricted wastes in tanks or
containers.
Permitted Facilities (Section 270.42)
Prior to the November 7, 1986, land disposal restric-
tions rule, permitted treatment facilities did not have
the same flexibility to make waste management
changes as interim status facilities. In the November
7th rulemaking, EPA made some changes (Section
270.42) which will allow permitted facilities to treat
restricted wastes more promptly and to increase the
availability of treatment capacity. A permitted facility
may now treat restricted wastes not identified in the
permit if the treatment is such that the treatment
residual meets the applicable treatment standards. In
addition, permitted facilities may treat new wastes as
long as such treatment does not pose substantially
different risks from the risks associated with wastes
included in the permit. These changes require an
EPA-approved minor permit modification.
EPA proposed in the December 11, 1986, notice to
give permitted treatment and storage facilities more
flexibility in managing wastes restricted from land
disposal. EPA proposed to allow these permitted
facilities, through the minor permit modification
process, to change their operations so as to treat or
store restricted wastes in tanks or containers. The
proposed rule would allow only those changes needed
to comply with the land disposal restrictions rule.
These permitted facilities would be required to submit
a major modification request, which EPA would
process at a later date, and to comply with all
applicable requirements of the RCRA Part 264
standards.
Testing and Recordkeeping (Section
268.7)
The testing and recordkeeping requirements of the
land disposal restrictions rule reflect EPA's philosophy
of tracking wastes from generation to ultimate
disposal. All restricted wastes, whether treated and
disposed on-site or sent off-site to a RCRA treatment
or disposal facility or to a non-RCRA recycling facility,
are subject to some testing and recordkeeping
requirements. Although recycling facilities may be
exempt from RCRA regulation, the wastes they
receive and the resulting residues are regulated by
RCRA and are subject to the land disposal
restrictions. Generators, treatment facilities, and land
disposal facilities each have specific responsibilities
under the land disposal restrictions rule; however, the
land disposal facility bears the ultimate responsibility
for ensuring that only wastes meeting the treatment
standards (or wastes that are subject to an exemption
or variance) are land disposed.
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Generator Responsibilities
The generator is responsible for testing his waste or
an extract of his waste (developed by using the
TCLP), or using knowledge of his waste, to determine
if his waste is restricted from land disposal. If the
generator determines that he is managing a restricted
waste, he is responsible for determining whether his
waste meets the applicable treatment standard. The
generator can also make this determination based
either on knowledge of the waste, or by testing the
waste or waste extract (developed by using the
TCLP). If the generator has used knowledge of his
waste (whether it is sent to a treatment facility or a
disposal facility) to determine the applicable treatment
standard, or to determine if the applicable standard
has been met without treatment, he must maintain
records (at the location where the waste is generated)
of all supporting data used to make the determination.
As prior to the land disposal restrictions, the generator
must also conduct a waste analysis if there is any
reason to believe that the waste composition or the
generating process has changed; he cannot rely on
his knowledge of the waste in such cases.
If the waste meets the treatment standard, the
generator may transport the waste directly to the
disposal facility, providing a notice with the following
information:
The EPA Hazardous Waste Number(s).
The applicable treatment standard(s).
The manifest number associated with the waste
shipment.
The waste analysis data (if available).
The generator must also provide a certification which
states that the waste delivered to the disposal facility
meets the treatment standard, and that the information
included in the notice is true, accurate, and complete.
If EPA has granted an extension to the effective date
for a particular waste, it is the generator's
responsibility to notify the land disposal facility.
For restricted wastes that do not meet the treatment
standard, the generator must send a notice with each
shipment to the treatment facility. The generator must
determine the appropriate treatment standard based
on waste analysis data, knowledge of the waste, or
both.
Generators which treat and/or dispose of restricted
waste on-site must also comply with the record-
keeping requirements of treatment and/or disposal
facilities (except for the manifest number).
Treatment Facility Responsibilities
Treatment facilities are responsible for treating
restricted wastes to the levels specified by the
applicable treatment standards or by the specified
technology(ies). A treatment facility also is responsible
for:
Keeping a copy of the notice and any available
waste analysis data provided by the generator in
the treatment facility's operating record.
Testing the treatment residual using the TCLP
(according to the frequency established in the
facility's waste analysis plan) to determine
whether it meets the waste extract concentration
level.
Conducting a waste analysis if there is any reason
to believe that the waste composition or the
treatment process has changed.
Where treatment residuals meet the treatment
standards, the treatment facility, like the generator
who ships waste directly to a disposal facility, must
submit a notice and certification to the disposal
facility. The certification must state that the treatment
standards have been met in accordance with the
prohibition on dilution, and that the information is true,
accurate, and complete.
Where treatment residuals do not meet the treatment
standards and the facility ships the residuals off-site to
another treatment facility for further treatment, the
notice requirements are the same as for the original
generator sending the wastes to the treatment facility.
Land Disposal Facility Responsibilities
Land disposal facilities are responsible for ensuring
that only wastes meeting the treatment standards (or
wastes that are subject to an exemption or variance)
are land disposed. In addition, land disposal facilities
must document that the waste has been treated in
accordance with the applicable EPA treatment
standards. The results of any waste analyses must be
placed in the land disposal facility's operating record,
along with a copy of all certifications and notices.
Treatment Standards for Solvents
(Section 268.41)
What Solvent Wastes Are Covered Under the
F001-F005 Listing? (Section 268.31)
Only solvent constituents listed in Table CCWE (Table
1-2), when used to solubilize (dissolve) or mobilize
other constituents, are considered spent solvents
under the land disposal restrictions rule. A solvent is
considered "spent" when it has been used and is no
longer fit for use without being regenerated,
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Table 1-2. Solvent Treatment Standards3 Table CCWE
Constituents of F001-F005
Spent Solvent Wastes
Acetone
n-Butyl alcohol
Carbon disulfide
Carbon tetrachloride
Chlorobenzene
Cresols (cresylic acid)
Cyclohexanone
1 ,2-Dichlorobenzene
Ethyl acetate
Ethylbenzene
Ethyl ether
Isobutanol
Methanol
Methylene chloride
Methyl ethyl ketone
Methyl isobutyl ketone
Nitrobenzene
Pyridine
Tetrachloroethylene
Toluene
1,1,1 -Trichloroethane
l,1,2-Trochloro-l,2,2-
trifluoroethane
Trichloroethylene
Trichlorofluoromethane
Xvlene
Extract Concentrations (mg/l)
Wastewater
0.05
5.00
1.05
0.05
0.15
2.82
0.125
0.65
0.05
0.05
0.05
5.00
0.25
0.20b
0.05
0.05
0.66
1.12
0.079
1.12
1.05
1.05
0.062
0.05
0.05
Other
0.59
5.00
4.81
0.96
0.05
0.75
0.75
0.125
0.75
0.053
0.75
5.00
0.75
0.96
0.75
0.33
0.125
0.33
0.05
0.33
0.41
0.96
0.091
0.96
0.15
a For determining the applicable treatment Standard, wastewaters
are defined as solvent-water mixtures containing less than or equal
to 1 percent total organic carbon.
& Treatment standard for wastewaters generated from
pharmaceutical plants is 12.7 mg/l.
reclaimed, or otherwise reprocessed. Examples of
spent solvents include solvents that are used as
degreasers, cleaners, fabric scourers, diluents,
extractants, and reaction and synthesis media.
Manufacturing process wastes containing F001-F005
solvent constituents are not spent solvents where the
solvent constituents "are reactants and not carriers
(solvents) in the process.
Basis for the Solvent Treatment Standards
EPA identified nine treatment technologies that are
demonstrated and commercially available for F001-
F005 spent solvents. Using data that represented only
well-designed and well-operated systems, EPA
calculated average performance values for each
specific waste treated with a particular technology.
Where one technology performed better than others,
EPA based the treatment standard on the best
technology. If several technologies performed equally
well, EPA averaged the performance values and
multiplied the average value by a variability factor to
derive the treatment standard. The variability factor
was calculated in to account for fluctuations inherent
in the normal process of well-designed and well-
operated treatment systems.
EPA established three separate treatability groups for
spent solvent wastes:
Wastewaters (defined for the purposes of Table
CCWE as solvent-water mixtures containing less
than or equal to 1 percent total organic carbon
(TOG) by weight).
Methylene chloride-containing wastewaters
containing less than or equal to 1 percent TOC
generated from pharmaceutical plants.
All other spent solvent wastes, including
wastewaters containing greater than 1 percent
TOC, solvent-containing solids, solvent-con-taining
sludges, and solvent contaminated soils.
Of the nine demonstrated treatment technologies,, the
following four technologies formed the basis for the
solvent treatment standards:
Steam stripping.
Biological treatment.
Activated carbon treatment.
Incineration.
The solvent treatment standards are set as
concentration levels based on the above technologies;
EPA is not requiring that these specific technologies
be used to meet the treatment standards. Table 1-2
lists the spent solvent treatment standards expressed
as eoncentrations in the treatment residual extract.
Effective Date of Solvent Land Disposal
Restrictions (Section 268,30)
The following spent solvent wastes (F001-F005) have
been granted the maximum two-year national
variance. Effective November 8, 1988, these wastes
are prohibited from disposal.
Wastes generated by small quantity generators of
100 to 1,000 kg/month of hazardous wastes.
Wastes resulting from CERCLA response actions
and RCRA corrective actions.
Solvent-water mixtures, solvent-containing sludges
or solids, and solvent-contaminated soil containing
less than one percent total F001-F005 solvent
constituents.
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Treatment Standards for Dioxins (Section
268.41)
The treatment standards for dioxin-containing wastes
F020, F021, F022, F023, F026, F027, and F028 are
based on incineration to 99.9999 percent destruction
and removal efficiency. The standards require
treatment to a level below the routinely achievable
detection limit of 1 ppb (using Method 8280 in SW-
846) in the waste extract for the specific isomers of
tetra-, penta-, and hexachloro-dibenzo-p-dioxins and -
dibenzofurans listed in Table CCWE. The treatment
standards for the chlorophenols also require treatment
to a level below the routinely achievable detection limit
in the waste extract as listed in Table CCWE.
The dioxin-containing waste treatment standards
expressed as concentrations in the treatment residual
extract are shown in Table 3.
Table 1-3. Dioxin Treatment Standards
Table CCWE
F020-FQ23 and F026-F028 Dioxin-Containing Extract
Wastes Concentrations
HxCOD - All Hexachlorodibenzo-p-dioxins < 1 ppb
HxCDF - All Hexachlorodibenzofurans < 1 ppb
PoCDD - All Pentach!orodibenzo-p-dioxins < 1 ppb
PoCOF - AH Pentachlorodibenzofurans < 1 ppb
TCDO - AH Tetrachlordibenzo-p-dioxins < 1 ppb
TCDF - AH Telrachlorodibenzofurans < 1 ppb
2,4,5-Trichtofophenol <0.05 ppm
2,4,6-TrtchlorophenoJ <0.05 ppm
2,3,4,6-Tetrachtorophenol <0.10 ppm
Penlachtorophenol <0.0i ppm
ppb-yg/l
Effective Date of Dioxin Land Disposal
Restrictions (Section 268.31)
EPA has determined that there is a lack of treatment
capacity nationwide to handle dioxin wastes; therefore,
EPA has granted the maximum two-year national
variance to the effective date of the dioxin land
disposal restrictions to allow time for the regulated
community to develop the necessary capacity.
Effective November 8, 1988, the F020-F023 and
F026-F028 dioxin-containing wastes are prohibited
from land disposal.
Information Requirements
Petition for a Variance From the Treatment
Standard
A petition from the treatment standard must include
the following information:
The petitioner's name and address.
The name, address, phone number, and EPA
identification number of the generating facility and
of the facility contact person.
A description of the waste generating processes
and feed materials.
A detailed description of the petitioner's waste
(including data and information on the physical
and chemical characteristics of the waste) that
EPA can use to compare the petitioner's waste to
the wastes considered by EPA in developing
BOAT.
If the waste has been treated, a description of the
treatment system, including the process design,
operating conditions, and an explanation of why
the treatment standards cannot be achieved using
the treatment system, or an explanation of why
the specified treatment technology is inappropriate
for the petitioner's waste.
If the waste has not been treated, an explanation
of why the petitioner believes the waste will react
to treatment differently from the wastes evaluated
by EPA in developing the treatment standard.
A description of any alternative treatment systems
examined by the petitioner, and, as appropriate,
the concentrations in the treatment residual (using
the TCLP) that can be achieved by applying such
treatment to the waste.
The dates of the sampling and testing.
A description of the methodologies and equipment
used to obtain representative samples.
A description of the sample handling and
preparation techniques.
A description of the tests performed (including
results).
Petition for a Case-by-Case Extension to the
Effective Date
A case-by-case petition must include the following
information:
A demonstration that a good faith effort has been
made to locate and contract with hazardous waste
treatment, recovery, or disposal facilities
nationwide to handle the waste.
A demonstration that the petitioner has entered
into a binding contract to construct or otherwise
provide adequate treatment, recovery, or disposal
capacity for the waste.
A demonstration that, due to circumstances
beyond the petitioner's control, alternative
treatment, recovery, or disposal capacity cannot
10
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reasonably be made available by the effective
date of the land disposal restriction.
A demonstration that the capacity being con-
structed or otherwise provided will be sufficient to
manage the waste.
A detailed schedule for obtaining all necessary
operating and construction permits and an outline
of how and when alternative capacity will be
available.
A demonstration that arrangements have been
made for adequate capacity to manage the waste
during the extension. This demonstration must
include an identification and description of all
waste management sites.
Petition for a "No Migration" Exemption
A "no migration" petition must include the following
information:
The identification and a full characterization of the
specific waste, including a comprehensive
chemical and physical characterization
The identification and a comprehensive
characterization of the disposal unit, including
background air, soil and water quality.
A demonstration that all waste and environmental
sampling, test, and analysis data are accurate and
reproducible.
A demonstration that EPA-approved sampling,
testing, and estimation techniques were used.
A demonstration that all simulation models for the
specific waste and disposal site conditions were
calibrated and that the models were verified by
actual measurements.
Analyses performed to identify and quantify any
aspects that could contribute significantly to
uncertainty regarding the suitability of the site,
including the potential for damage from
earthquakes, floods, severe storms, droughts, or
other natural phenomena.
A quality assurance and quality control plan that
addresses all aspects of the "no migration"
demonstration.
11
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Chapter 2
Title III
The Community's Right to Know
Introduction
In October 1986, Congress passed the Emergency
Planning and Community Right-to-Know Act as Title III
of the Superfund Amendments and Reauthorization
Act (SARA). Title ill establishes requirements for
federal, state, and local governments and industry
regarding emergency planning and community right-
to-know reporting on hazardous and toxic chemicals.
This act is expected to stimulate a wealth of new
information on the quantities and sources of
hazardous substances in the environment.
An Overview of Title III
There are four major sections included under Title III.
These are:
Emergency Planning - Sections 301-303.
Emergency Notification - Section 304.
Community Right-to-Know Reporting Require-
ments - Sections 311-312.
Toxic Chemical Release Reporting - Section 313.
Under Sections 301-303, state governors are required
to designate state emergency response commissions,
who in turn designate local emergency planning
districts and local emergency planning committees
(LEPC). As of late 1988, state commissions have
designated over 4,000 LEPCs. Each LEPC is
responsible for developing an emergency response
plan, which was due by October 1988.
Facilities with "reportable quantities" of the specified
366 "extremely hazardous substances" must
cooperate with state and local planning authorities to
prepare comprehensive emergency plans. Section
304 specifies that facilities which produce, use, or
store specified hazardous substances must report
accidental releases of those substances above certain
quantities to state and local response officials. Under
Sections 311-312, all facilities that are required to
prepare Material Safety Data Sheets (MSDSs) on the
hazardous chemicals used, processed, or stored at
the facility in certain quantities, must submit copies of
the MSDSs or a list of the materials (for which
MSDSs are available) to state and local authorities.
These authorities, including fire departments, must
have reports on the inventories of chemicals for which
MSDSs exist at each facility. This report should also
include locations of these materials.
Section 313 specifies that owners and operators of
certain facilities that manufacture, process, or
otherwise use one of the listed chemicals must
annually report releases to the environment. This
report is sometimes referred to as the Toxic
Chemicals Release Inventory. Facilities handling
solvents are likely to be subject to the reporting
requirements under one or more of the sections of
Title III.
The list of key dates for reporting under Title III is
shown in Table 2-1.
Emergency Notification - Section 304
Under Title III, Section 304, facilities must immediately
notify the local emergency planning committee and
the state emergency response commission if there is
a release of a listed substance beyond the reportable
quantity. These substances were listed in the Federal
Register on November 17, 1986, and are summarized
in Table 2-2. This initial notification can be done by
telephone, radio, or in person. The notification must
include:
Chemical name.
An indication of whether the substance is
extremely hazardous.
A quantity estimate for environmental release.
The time and duration of the release.
The medium into which the release occurred.
The known or anticipated acute or chronic health
risks associated with the material. This should
include recommendations for medical attention, if
this is applicable.
The proper precautions.
« The name and telephone number of the contact
person at the facility.
13
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Tablo 2-1. Selected Key Dates for Reporting Under Title III
Date
Title
November 17,1986
November 17,1986
January 27.1987
March 17,1987
April 17, 1987
April 28, 1987
May 17, 1987
Jtm04, 1987
July 17, 1987
August 17,1987, (or 30 days after desig-
nation of districts, whichever is sooner)
September 17,1987, (or 30 days after
committee is formed, whichever is sooner)
October 17,1987
March 1,1988 (and annually thereafter)
June 1988
July 1,1988, (and annually thereafter)
October 17,1988
March 1,1989 (and annually thereafter)
April 30,1989
March 1,1990 (and annually thereafter)
June 20,1991
October 17,1991
EPA published Interim List of Extremely Hazardous Substances and Planning Threshold Quantities
(EHS and PTQ) in Federal Register (§302, 303, 304)
EPA initiates comprehensive review of emergency systems (§305(b))
Format for Emergency Inventory Forms and reporting requirements published in federal Register
(§311,312)
National Response Team published guidance for preparation and implementation of emergency
plans (§303(f))
Governors appoint State Emergency Response Commissions (SERC) (§301 (a))
EPA published Final List of EHS and PTQ in FR (§302, 3, 4)
Facilities subject to §302 planning requirements notify SERC (§302(c))
Interim report on emergency system review due to Congress (§305(b))
EPA published proposed toxic chemical release (i.e., emissions inventory) form (§3l3(g))
SERC designates emergency planning districts (§301 (b))
SERC appoints members of local emergency planning committees (§301 (c))
Covered facility notifies local planning committee of selection of a facility representative (§303(d)(i))
MSDS or list of MSDS chemicals submitted to state commission, local committee, and local fire
department by covered manufacturing and importing facility (§311 (d))
Covered facilities submit their inventory forms to state commission, local committee, and local fire
department (§312(a)(2))
Final report on emergency systems study submitted to Congress (§305(b))
Covered facilities submit initial toxic chemical forms to EPA and designated state officials (§3l3(a))
Local emergency planning committees (LEPC) complete preparation of an emergency plan (§303(a))
Covered non-manufacturing facilities submit inventory reports to SERC, LEPC, and fire department
(§312(a)(2))
Covered construction facilities submit MSDS or list of MSDS chemicals to SERC, LEPC, and fire
department (§311 (d)).
Covered construction facilities submit inventory reports to SERC, LEPC, and fire department
(§3l2(a)(2))
Comptroller General report to Congress, on toxic chemical release information collection, use, and
availability (§313(K)) '
EPA report to Congress on Mass Balance Study (§313(1))
This notification must be followed by a written report
which will include an update of the initial report as well
as information on the response actions which were
taken. The report must be made to the appropriate
state and local committee or to the designated
officials.
Community Right-to-Know Reporting
Requirements - Sections 311 - 312
Under Section 311, those facilities which must
prepare or have available MSDSs under Occupational
Safety and Health Administration (OSHA) regulations
(29 CFR 1910.1200 - the Hazard Communication
Standard), are required to submit copies of the
MSDSs or a list of the chemicals for which MSDSs
are kept. This information must be sent to:
The local emergency planning committee.
The state emergency response commission.
*
The local fire department.
The list must be organized in the categories of health
and physical hazards as defined by OSHA in the
Hazard Communication Standard (29 CFR
1910.1200). If the list alone is sent, the MSDS must
be provided if requested by any of the agencies
involved. It is necessary to update the MSDSs on file
as new information becomes available.
Section 312 requires the submission of emergency
and hazardous chemical inventory forms to:
The local emergency planning committee.
The state emergency response commission.
The local fire department.
14
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The same chemicals are reported under Section 312
and Section 311. Section 312, however, is a two-
tiered submission. Tier I reporting includes:
An estimated (in ranges) maximum of each
chemical hazard category present on a calendar
year and an average daily basis.
The general location of the hazardous chemicals
for each category.
Tier II reporting includes (upon request):
The chemical or common name of the substance.
An estimate (in ranges) of the maximum inventory
and of average daily amount for the preceding
calendar year.
A description of the chemical storage.
The location of the chemical at the facility.
An indication of whether the specific location
information is to be withheld from public
disclosure.
Under Section 312, the public may request copies of
the Tier II information from the state and local
authorities.
Toxic Chemical Release Reporting -
Section 313
The Environmental Protection Agency, under Title III,
is required to establish an inventory of these toxic
chemical emissions.
Facilities are required to report to EPA and to their
respective state releases of covered chemicals to air,
water, or land and those transferred to off-site
facilities. These reports are required from owners and
Table 2-2. Summary of Chemical Lists for Title III
List
Section
operators of facilities in Standard Industrial
Classification Codes 20 - 39:
That have 10 or more full-time employees; and ,
That manufacture, process, or otherwise use a
listed chemical in excess of the threshold
quantities.
The listed materials are those which are included on
the combined Maryland and New Jersey toxic
substances list as required by the law. EPA can
modify this list, if necessary, when considering the
following factors:
Is the substance known to cause cancer or
serious reproductive or neurological disorders,
genetic mutations, or chronic health effects?
Can the substance cause serious health effects
as a result of releases to the environment?
Can the substance cause an adverse effect on
the environment because of its toxicity,
persistence, or bioaccumulation?
Chemicals can be deleted from this list as well if there
is insufficient evidence to establish any of these same
factors. The lists used in Title HI reporting are
summarized in Table 2-2.
The Toxic Chemical Release Reporting Form includes
the following facility-specific information:
The name, location, and type of business.
Whether the chemical is manufactured,
processed, or otherwise used, and the general
categories of use of the chemical.
Purpose
List of Extremely Hazardous Substances
(FR 11/17/86)
Substances requiring noti-fication under
Section 103(a) of CERCLA
Hazardous chemicals considered physical
or health hazards under OSHA's Hazard
Communication Standard
Toxic chemicals identified in the law
§302: Emergency
Planning
§304: Emergency
Notification
§311/:MSDSS and
312 Emergency
Inventory
§304: Emergency
Notification
§304: Emergency
Notification
§311: Materials Safety
Data Sheets
§312: Emergency
Inventory
§313: Toxic Chemical
Release
Reporting
Facilities with more than estimated planning quantities of these
substances must notify the SERC and LEPC
Initial focus for preparation of emergency plans by LEPCs
Certain releases of these substances trigger §304 notification to SERC
and LEPC
Separate and lower thresholds are established for these substances of
concern for the MSDS and Tier l/ll reporting requirements
Certain releases of these substances trigger §304 notification to state
commissions and local committees as well as §!03(a) requirement for
National Response Center notification
Identifies facilities subject to emergency notification requirements
MSDSs or lists of MSDS chemicals provided by covered facilities to
state commission, local committee, and local fire department
Covered facilities provide site-specific information on chemicals to state
commission, local committee, and local fire departments
Tier l/ll inventory forms must be provided by facilities to SERC, LEPC,
and fire departments
These chemicals are reported on an emissions inventory to inform
government officials and the public about releases of toxic chemicals into
the environment
15
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An estimate (range) of the maximum amounts of
the toxic chemical present at the facility at any
one time during the preceding year.
Waste treatment/disposal methods and the
efficiency of the methods for each waste stream.
* Quantity of the chemical .entering each
environmental medium annually.
A certification by a senior official that the report is
complete and accurate.
The total quantity of a chemical released during the
year must be reported. This will include both
accidental spills and routine emissions, even those
which are covered by permits. Separate estimates
must be provided for releases to air, water, and land.
If waste materials are shipped to off-site locations,
these must be identified along with the quantities sent.
There must be a valid basis or documentation for the
estimates made of these quantities.
EPA is required by law to make the data in the reports
available to the public through a computer database
and by other means. The public can thus access the
information easily, which is an unprecedented
situation.
Conclusions
Industry, environmental groups, and state and local
governments, working in conjunction with the EPA,
have a responsibility to help the public understand the
significance of hazardous substances in the
environment. More must be done than to simply
collect and verify the information and make it available
to the public. Educational programs are being
developed to help inform community leaders, the
news media, and citizens about the relationship
between hazardous substances in the environment
and human health. With this information, America's
communities should be better prepared than they
have been in the past to make informed, reasoned
risk decisions that will best reflect the needs and
values of their citizens.
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Chapter 3
Solvent Waste Burning Regulations
Joseph Galbraith
U.S. Environmental Protection Agency
Region VII
Kansas City, KS 66101
The terms "resource conservation" and "recovery" in
the Resource Conservation and Recovery Act (RCRA)
are misleading. Many pages in the Federal Register
and the Code of Federal Regulations deal with
treating, storing, and disposing of various materials
without reference to recycling, reuse, etc., which are
considered exemptions.
Spent solvents and other hazardous wastes first
became subject to regulation on May 19, 1980. The
regulations differentiated between energy recovery
and disposal. They controlled the incineration of
hazardous waste but exempted the burning of
hazardous wastes for energy recovery. Storage and
transportation were covered when the waste was
burned on-site or when it was sent directly to a
burner. If the wastes were processed by a middleman,
they were subject to the regulation until they went
through the refining process. Any waste that was
characteristic (ignitable) that was not a sludge being
stored or sent for energy recovery, was exempt. This
allowed the introduction of foreign materials into
waste. In 1983, EPA developed an enforcement policy
to ensure that only legitimate waste would be burned
for energy recovery. This policy was published in the
Federal Register on March 16, 1983, and is still in
effect. It states that a waste must have a heat content
of 5,000 to 8,000 btu per pound and a chlorine
content of two to five percent to be legitimate for
burning for energy recovery. A waste with a lower
heating value is considered sham recycling and
subject to the incineration regulations. A higher
chlorine content is detrimental to the process being
used (e.g., boiler tubes, cement kilns).
In its January 1985 revision to the definition of solid
waste, EPA stated that listed wastes and sludges
were subject to storage and transportation prior to
burning, including the processing and blending by a
third party or parties that neither generated nor burned
the materials. In November 1985, EPA published
burner/blender regulations, which identified storage,
transportation, and administrative controls for
hazardous wastes that were used as fuels or to
produce a fuel.
Wastes that were hazardous only because they were
characteristic were no longer exempt. In addition, the
rule prohibited the burning of hazardous waste fuel in
any nonindustrial boiler unless that boiler complied
with the incinerator regulations. A nonindustrial boiler
may not be used for burning hazardous waste fuel
even today. Notification requirements were also
required under these burner/blender regulations. All
parties - generators, blenders, marketers, and the
burning facility - are required to notify EPA and/or the
states in accordance with 40 CFR Part 266.
In addition to RCRA materials, the Toxic Substances
Control Act (TSCA) regulates polychlorinated
biphenyls (PCBs), which are found in used oil and
occasionally in solvents. Solvents containing
detectable PCBs may not be burned for energy
recovery.
Hazardous waste may not be burned in any
nonindustrial boiler. Hazardous waste with a heating
value greater than 5,000 to 8,000 btu per pound may
be used for energy recovery in utility boilers, boilers
that generate electricity, industrial boilers, and
industrial furnaces. Regional limitations on chlorine
content may also be imposed on these fuels: The
notification requirements in 40 CFR Part 266 must be
met. Residues from burning in these boilers are
subject to regulation except for coal-fired boilers
where coal is greater than 50 percent of the fuel.
Residues from hazardous waste fuel burned in gas-
and oil-fired boilers are subject to regulation. Residue
from a coal-fired boiler with fuel that is <50 percent
coal are subject to regulation. Conditionally-exempt
small-quantity generators must comply with the
notification requirements but are exempt from the
regulations governing permit acquisition. Their
regulations are listed in Part 261.
In May 1987, EPA proposed new regulations for
boilers and industrial furnaces. Because of criticism, it
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is revising them and developing incinerator
regulations. Many of the comments that were received
urged EPA to use a standard approach to both boilers
and incinerators. As a result, a new set of proposed
boiler regulations is under review. The proposed
regulations are similar to Part 264 Subpart O, which
deals with incinerators.
Under the proposed boiler regulations, all
nonindustrial, industrial, and utility boilers and all
industrial furnaces that burn hazardous wastes will be
required to have permits. The performance standards
are risk-based and are similar to Part 264, Subpart 0
incinerator standards. Most units will be required to
conduct trial burns, but there are provisions for an
exemption to the trial burn. Time frames for interim
status notification, filing of applications, and the
installation of required monitoring equipment will be
included in the proposed regulations. At this time, the
proposal calls for the regulations to be promulgated
under Part 266. EPA will probably request comments
on permitting them under Part 264, which will make
the same set of standards apply to both boilers and
incinerators.
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Chapter 4
Waste Minimization Liability Issues
Robert A. Wyman
Amanda E. Register
Latham & Watkins
Los Angeles, CA 90071
Introduction
This country spends more than $70 billion each year
on environmental protection and compliance. A large
part of this expenditure has been directed towards the
proper management and disposal of hazardous
wastes as specified in the Resource Conservation and
Recovery Act of 1976 (RCRA),1 and the
Comprehensive Environmental Response, Compen-
sation, and Liability Act of 1980 (CERCLA).2
The Office of Technology Assessment (OTA)
estimates that industry today produces at least 575
million tons of hazardous wastes per year.
Furthermore, EPA has concluded that many parts of
the country lack or will soon lack adequate treatment
and disposal capacity to deal with the volume of
hazardous waste generated. Even where there is
sufficient treatment and disposal capacity, the
treatment or disposal methods have failed to
eliminate, or even reduce to acceptable levels, the
risk of an unintentional release. At the same time,
industry has sought ways to reduce liabilities
associated with hazardous substance handling and
disposal. These trends have motivated federal and
state legislatures to focus attention towards waste
reduction strategies such as recycling and source
reduction and away from "end-of-the-pipe" solutions
such as the permitting of new landfills and waste
treatment, storage, and disposal (TSD) facilities.
By amending RCRA in 1984, Congress established
hazardous waste reduction as a national priority.3
These amendments, known as the Hazardous and
Solid Waste Amendments of 1984 (HSWA), impose
substantial new legal responsibilities on hazardous
waste generators, treaters, and disposers. HSWA
creates a presumption against land-based disposal by
requiring that hazardous waste generators voluntarily
institute in-house waste minimization programs, meet
pre-disposal treatment standards for certain hazardous
wastes, and equip new landfills and other waste
disposal facilities with additional technological controls
prior to receiving wastes.
This chapter addresses the legal incentives that
HSWA and related EPA regulations create to reduce
hazardous waste production. (Note: Specific land
disposal and waste minimization requirements of
HSWA are described in Chapter 1 but are
summarized with more complete references and notes
here.) A discussion follows of three compliance
options available to hazardous waste generators:
source reduction, recycling and resource recovery,
and treatment and land disposal. Each compliance
option is analyzed in terms of the liability risks and/or
protections it provides, as well as other general short-
and long-term considerations that a generator should
take into account before selecting a particular option.
HSWA - Waste Treatment and
Minimization Requirements
Land Disposal Ban
Disposal Prohibitions
HSWA mandates that the continued land disposal of
untreated hazardous wastes beyond specified dates is
prohibited4 unless EPA determines that the prohibition
is not necessary in order to protect human health and
the environment for as long as the waste remains
hazardous.5 In addition, HSWA requires EPA to
identify levels or methods of treatment, if any, that
substantially diminish the toxicity or migration potential
of a waste and minimize threats to human health and
the environment. Wastes treated in accordance with
standards set under this section are not subject to the
prohibition and may be land-disposed.6-7
Timetable for Compliance
HSWA sets forth a detailed timeline for EPA
determination of treatment standards. If the agency
fails to meet a statutory deadline, further land disposal
of the affected group of wastes is automatically
prohibited or conditionally prohibited under a
"hammer" provision. EPA was required to set
treatment standards for F001 to F005 solvents and
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dioxin wastes by November 8, 1986, and for
"California List" wastes by July 8, 1987. The agency
has completed both sets of standards.8 Furthermore,
the agency must review and set standards for the first
one-third of its remaining listed wastes by August 8,
1988; the second one-third by June 8, 1989; and the
last one-third by May 8, 1990.9
Exemptions and Variances
A generator (or any interested person) may petition
that a certain waste be exempted from the land
disposal restrictions. The petitioner must demonstrate,
to a reasonable degree of certainty, that there will be
no migration of hazardous constituents from the land
disposal unit or injection zone (including air emissions)
for as long as the waste remains hazardous.10
In addition to an exemption, three types of variances
are available under the statute: 1) a variance based on
lack of national capacity; 2) a variance from the
treatment standard; and 3) a case-by-case extension.
First, EPA can grant a national variance of up to two
years if the agency determines that there is a
nationwide lack of capacity to treat specific wastes.
Because EPA has determined that the land disposal
restrictions will create a national shortage of
wastewater treatment and incineration capacity, the
agency has granted such a variance for: 1) small
quantity generators of 100 to 1,000 kg of non-acute
hazardous waste per month or less than 1 kg of acute
hazardous waste per month; 2) solvent wastes
generated by response or corrective actions taken
under CERCLA or RCRA; and 3) dilute F001 to F005
solvent wastes containing less than one percent total
organic constituents.11 As a result, these subgroups
do not have to comply with treatment standards until
November 8, 1988, provided that their wastes are
managed in facilities that are in compliance with the
requirements' of RCRA 3004(o). Landfills or other
hazardous waste facilities receiving permits after
November 8, 1984, must contain double liners with
leachate collection and leak detection systems and
ground-water monitors.12
Second, a generator may request a variance from the
treatment standard if the waste produced is a unique
waste that cannot be treated to the levels specified as
the treatment standard because, for example, the
waste does not fit into one of the Best Demonstrated
Available Technology (BOAT) treatability groups.13
Third, the agency will consider granting individual
extensions of up to two years if the applicant can
demonstrate: 1) that a good-faith effort has been
made to locate and contract with alternative
technologies nationwide; 2) that a binding contract has
been entered into to construct or otherwise provide
alternative treatment, recovery, or disposal capacity
that cannot reasonably be made available by the
applicable effective date due to circumstances beyond
the applicant's control. In demonstrating that capacity
cannot reasonably be made available, the applicant
may show that it is not feasible to provide such
capacity because of technical and practical difficulties;
and 3) that the capacity will be sufficient to manage all
of the waste covered by the application. In addition,
an applicant must provide a detailed schedule for
providing capacity and document locations with
adequate capacity to manage its wastes during the
extension. Any landfill or surface impoundment
receiving waste during the extension must comply
with the technology requirements of RCRA 3004(o).i*
In the event that an extension is granted, an applicant
is exempted from the disposal restrictions for the
length of the extension, including the conditional
storage prohibitions discussed below.
Storage Prohibitions
The agency has set forth three different time limits for
the storage of restricted wastes. First, facility owners
and operators may store restricted wastes as needed
to accumulate sufficient quantities necessary for
proper recovery, treatment, or disposal. If storage
exceeds one year, however, the burden of proof is on
the owner/operator to show that such storage is
necessary. Second, transporters of restricted wastes
are subject to a 10-day storage limit. Third, generators
who store restricted wastes in excess of the
accumulation time limits set forth in 40 CFR .262.34
must obtain interim status and eventually a permit.15
For large quantity generators, the applicable time limit
is 90 days; small quantity generators can store wastes
for 180 or 270 days depending on transportation
distances.
Treatment Standards
Congress has required EPA to use a Best
Demonstrated Available Technology (BOAT)
framework to establish treatment standards for
restricted wastes. H§WA specifies that BOAT rrtay.be
expressed as either a performance standard or a
method of treatment. The agency has expressed a
preference for concentration-based performance
standards to ensure that the technology is properly
operated and to allow those regulated the greatest
degree of flexibility possible.16 In order to determine
whether a waste requires treatment and whether
applicable treatment standards have been met, the
Toxicity Characteristic Leaching Procedure (TCLP)
must be used. ........
Treatment Standards for F001 to F005 Spent Solvents
EPA determined final BOAT treatment standards for
spent solvents on November 7, 1986.17 The
standards are expressed as concentrations in the
treatment residual extract and therefore allow use of
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any technology that can meet the standard. The
technologies utilized by EPA in setting the standards
were steam stripping, biological treatment, carbon
adsorption, and incineration.18 Dilution is specifically
prohibited as a substitute for treatment. 19
Industries most affected by the "solvent wastes
standards include those where solvents are used as
reactant carriers, for surface preparation, for
degreasing, or as a base for paint and ink.
Testing and Recordkeeping Requirements
Although the agency has acknowledged that the
ultimate responsibility for proper disposal of restricted
wastes lies with the land disposal facilities, it has
imposed substantial waste analysis, notice, and
recordkeeping requirements on generators and
treatment facilities as well.
Generator Requirements
The generator must first test its hazardous wastes
either by using the Toxicity Characteristic Leaching
Procedure or by relying on its knowledge of the waste
to determine if the waste is restricted from land
disposal.20
If the waste is restricted, the generator must notify the
treatment or recycling facility in writing at the time of
shipment of the appropriate treatment standard for the
waste, the EPA Hazardous Waste Number, the
manifest number associated with the shipment of
waste, and any available waste analysis data. The
treatment or recycling facility (or the generator itself if
it is also the TSD facility) must keep a record of the
notice.21
A generator that determines that the waste can be
land-disposed without treatment must submit to the
disposal facility a certification statement22 and a
notice which contains the EPA Hazardous Waste
Number, the manifest number, the applicable
treatment standard(s), and any available waste
analysis data. Generators disposing on-site must keep
the same information in the operating record. The
above requirements apply to all generators dealing
with restricted wastes, whether they are land
disposing the wastes or merely recycling or reusing
them.23
Treatment Facility Requirements
The treatment facility is responsible for treating the
waste in accordance with the applicable treatment
standard, and must test waste residues under its
waste analysis plan and certify24 its results to the the
disposal facility. The same requirements would apply
to a recycling facility disposing of hazardous waste
residues. If further treatment is required such that the
waste must be shipped to another treatment or
recycling facility, the treatment or recycling facility
initiating shipment is subject to the notice
requirements applicable to generators.25
Land Disposal Facility Requirements
In addition to maintaining all notices, certifications, and
waste data in its operating records, a land disposal
facility must have a testing procedure for ensuring that
the wastes received conform to the certifications
made by generators and treatment facilities and are in
compliance with the applicable treatment standards,^
Generator Liability for Noncompliance with Land
Disposal Restrictions
A generator could be held liable for noncompiiance
with land disposal restrictions in at least two ways.
First, if a generator's hazardous wastes were not
being treated properly and, therefore, exceeding
treatment standard levels at the time of disposal, EPA
could track the wastes back to the generator through
the manifest system and impose penalties of up to
$25,000 per day for noncompiiance with RCRA
requirements.27 Such a result could occur even if the
generator were to send its wastes to a recycler and
the recycler failed to treat the wastes properly prior to
disposal. As a practical matter, however, EPA may
choose to institute enforcement proceedings against
the the noncomplying TSD facility before trying to
locate the responsible generator.
Second, a generator could be held criminally liable
under RCRA 3008(d) (3) if, in sending its wastes
directly to a land disposal facility, the generator fails to
certify or falsely certifies under 40 CFR 268.7 that the
wastes can be land-disposed without further
treatment.
Waste Minimization
Statutory Requirements
HSWA mandates that as of September 1, 1985,
generators are required to certify on hazardous waste
manifests and on-site treatment, storage, and disposal
permit applications that: 1) the generator has a
program in place to reduce the volume or quantity and
toxicity of hazardous wastes to the degree determined
by the generator to be economically practicable; and
2) that the waste management methods used by the
generator minimize present and future threats to
human health and the environment.28 EPA has
revised the Uniform Hazardous Waste Manifest Form
to include a supplemental statement in Item 16
containing the required certification.29.30 |n addition,
generators must report to EPA at least biannually on
the results of efforts undertaken during the year to
minimize wastes.31
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EPA has published 1987 waste minimization reporting
forms (EPA Form 8700-13A, 5-80, Rev. 11-85 and 12-
87) to be completed by all generators that, in 1987,
met or exceeded the minimum quantity reporting
requirements (1,000 kg or more of hazardous waste
per month or accumulated at any time; more than 1
kg of acute hazardous waste per month or
accumulated at any time; or more than 100 kg of spill
cleanup material contaminated with acute hazardous
waste accumulated at any time). Generators must
comply with state reporting requirements if the state
has been authorized to administer a RCRA program.
The reporting forms were due by April 1, 1988, with
written requests for extensions to May 1, 1988,
allowed. No information may be withheld on the basis
of confidentiality, although a business may assert a
confidentiality claim.
Description of Waste Minimization Activities
In its October 1986 Report to Congress, EPA broadly
defines waste minimization as: "The reduction, to the
extent feasible, of hazardous waste that is generated
or subsequently treated, stored, or disposed of. It
includes any source reduction of recycling activity
undertaken by a generator that results in either: 1) the
reduction of total volume or quantity of hazardous
waste; or 2) the reduction of toxicity of hazardous
waste, or both, so long as such reduction is
consistent with the goal of minimizing present and
future threats to human health and the environment.32
Included in the definition of waste minimization is the
concept of waste treatment, encompassing
technologies such as incineration, chemical detox-
ification, and biological treatments.33 In addition, EPA
has indicated that in certain circumstances waste
concentration and encapsulation techniques, or even
volume reduction alone, may be beneficial waste
minimization practices if they enhance protection of
the environment.34
Although EPA has defined waste minimization
practices broadly to include source reduction,
recycling, and treatment techniques, its preferred
waste management hierarchy, in descending order, is
as follows:
Waste reduction: Reducing the amount of waste
at the source through changes in industrial
processes, including some types of treatment
processes, process modifications, feedstock
substitutions or improvements in feedstock purity,
various housekeeping and management practices,
increases in the" efficiency of machinery, and
recycling within a process.
Waste separation and concentration: Isolating
wastes from mixtures in which they occur.
Waste exchange: Transferring wastes through
clearinghouses so that they can be recycled in
industrial processes.
Energy/material Recovery: Revising and recycling
wastes for the original or some other purpose,
such as fo'r materials recovery or energy
production.
Incineration/treatment: Destroying, detoxifying, and
neutralizing wastes into less harmful substances.
Secure land disposal: Depositing wastes on land
using volume reduction, encapsulation, leachate
containment, monitoring, and controlled air and
surface/subsidence water releases.35
Generator Liability for Noncompliance With Waste
Minimization Requirements
Although the HSWA waste minimization provisions
require several certifications from the generator,
legislative reports make it clear that these provisions
are solely intended to encourage generators to
voluntarily institute waste reduction programs on the
basis of economic practicability. As such, the
amendments require only that generators make a
good faith effort to reduce wastes in light of individual
circumstances; judgments made by generators are not
subject to external regulatory action, nor do they
create civil or criminal liabilities.36 Thus, from an
enforcement perspective, EPA will be concerned
primarily with compliance with the certification
signatory requirements.37
Waste minimization programs are strictly voluntary at
this point, but legal responsibilities for generators
could change in the near future. Although EPA
recommended in its October 1986 report that the
consideration of mandatory programs, including
performance standards and required management
practices, be deferred until additional data on
hazardous waste generation and management could
be gathered and analyzed, the agency has committed
to report back to Congress in December of 1990 on
the desirability and feasibility of a prescriptive
approach. Furthermore, EPA has stated that if
mandatory controls are needed in the interim, it will
institute them under the authority that currently exists
under such provisions as Section 6 of the Toxic
Substances Control Act (TSCA).S8 EPA's short-term
strategy includes: 1) publication of nonbinding
guidelines to generators on what constitutes
acceptable waste minimization practices; 2) provision
of technical and informational assistance to
generators;3^ and 3) encouragement of voluntary
waste minimization concepts within the review of new
chemicals under TSCA Section 5.40 EPA could also
recommend legislative amendments to Congress as
part of the next RCRA reauthorization, such as: 1)
prohibiting consideration of certain types of waste
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management practices as waste minimization (e.g.,
those practices that result in adverse cross-media
pollution transfers); 2) providing formal guidance as to
what may be certified as waste minimization; and 3)
requiring written support from generators who certify
that there is no economically practical alternative to
waste management practices which the agency has
not approved.41.42
If EPA-recommended waste reduction techniques are
to become mandatory in the future, those companies
that invest in such techniques at an early stage will
find the transition easier. Therefore, as a practical
matter, there is a substantial incentive even under this
voluntary program for generators to conduct waste
audits and implement programs now. Generators may
seek EPA clarification on waste minimization practices
by letter to the agency.43
A final liability consideration under the waste
minimization requirements deals with possible suits
against generators by persons alleging injury from
improper exposure to wastes produced by the
generator. If the defendant generator has not instituted
waste reduction measures in its plant, but the majority
of its industry has (either voluntarily or by law), such
noncompliance could conceivably be used against the
generator as evidence of negligence.
Liability Considerations
Because source reduction is in effect a waste
avoidance technique that utilizes in-house practices to
reduce waste generation, there is very little, if any,
liability risk associated with this option (assuming
proper management and no leaks or spills within the
facility).45 Coupled with potentially huge economic
savings for a company, the reduced liability aspects of
source reduction can make it an attractive compliance
option for generators. However, many products cannot
be manufactured without producing some hazardous
wastes; therefore, source reduction techniques will
usually have to be combined with other compliance
options such as recycling or treatment.
Other Considerations
Other factors may present practical limitations to
source reduction and prevent a company from fully
utilizing this option. Such factors include lack of
sufficient capital to institute process changes,
technical barriers such as lack of suitable engineering
information, and regulatory barriers such as the
possibility that the installation of new equipment will
be considered treatment under RCRA and require a
treatment, storage, and disposal facility (TSDF)
permit.46'47
Complying with Waste Treatment and
Minimization Requirements: Generation
Options and the "Liability Hierarchy"
Several management options exist for a generator
required to dispose of wastes in accordance with the
HSWA land disposal and waste minimization
requirements, including: 1) reducing waste at the
source; 2) on-site recycling and resource recovery; 3)
off-site recycling and resource recovery; 4) on-site
treatment and disposal of wastes (or obtaining a
variance from the land disposal restrictions and
disposing of wastes untreated); or 5) off-site treatment
and disposal of wastes (or obtaining a variance from
the land disposal restrictions and disposing of wastes
untreated). This section discusses these options in
order of increasing potential generator liability, and will
highlight short- and long-term considerations important
for generators intending to use a specific option or
combination of options.
Option One: Source Reduction
As discussed previously, EPA has defined source
reduction as any action that reduces the amount of
waste exiting from a process.44 Source reduction
techniques include process modifications, feedstock
substitutions or improvements in feedstock purity,
various housekeeping and management practices, and
increases in machinery efficiency.
Option Two: Recycling and Resource Recovery
A material is recycled if it is used, reused, or
reclaimed.48 A material is used or reused if it is either
employed as an ingredient in an industrial process to
make a product or employed in a particular function or
application as an effective substitute for a commercial
product.49 A material is reclaimed if it is processed to
recover a usable product or if it is regenerated, such
as regeneration of spent solvents.50
Some recycled materials are considered solid wastes
under RCRA 6903(27) and therefore are subject to
RCRA regulation. The residues resulting from these
recycled materials are also regulated under RCRA
unless they are formally delisted under 40 CFR
260.22.51
EPA determines whether a recycled material is a
RCRA solid waste by examining the nature of the
material and of the recycling activity involved. The
agency has identified five categories of secondary
materials, which include spent materials, sludges, by-
products, commercial chemical products, and scrap
metal. According to EPA, these secondary materials
are RCRA solid wastes when they are disposed of;
burned for energy recovery, or used to produce a fuel;
reclaimed; accumulated speculatively; or inherently
wastelike, such as dioxin-containing wastes.52
According to the 1985 EPA regulations, secondary
materials were not considered to be RCRA solid
wastes if they were: 1) used or reused as ingredients
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or feedstocks in production processes without first
being reclaimed; 2) used or reused as effective
substitutes for commercial products; or 3) returned
to the original primary production process in which
they were generated without first being reclaimed
(closed-loop exception).53 Thus, EPA drew a
distinction in the 1985 regulations between wastes
that were discarded or reclaimed prior to reuse and
those that were immediately reinserted into an on-site
production process. The former EPA considered to be
RCRA solid wastes; the latter were not solid wastes
and therefore not regulated under RCRA.
In the 1987 case of American Mining Congress v.
EPA, however, the DC Appellate Court ruled that
EPA's 1985 interpretation of recycled wastes was too
stringent. The court held that materials used or reused
in an ongoing manufacturing or industrial process are
not subject to RCRA's jurisdiction, even if these
materials are reclaimed first.54 The court explained
that these materials are not within RCRA's jurisdiction
because "they have not yet become part of the waste
disposal problem; rather, they are destined for
beneficial reuse or recycling in a continuous process
by the generating industry itself."55 Both petroleum
refiners and mining industries were involved in the
case.
In response to the American Mining case, EPA
published proposed amendments to the recycling
regulations on January 8, 1988.56 The proposed
amendments carve out a narrow exemption for
reclaimed sludges and by-products that are used in
ongoing manufacturing operations such as refining
and smelting processes, and are characterized by
continuous extraction of material values from an
original raw material. Materials that are used in this
manner are not considered to be solid wastes and
therefore are exempt from RCRA regulation. EPA
considers the following factors in determining whether
the use of a reclaimed sludge or by-product qualifies
as part of an'ongoing manufacturing process: 1)
industry practice; 2) process continuity; 3) similarity to
the principal activity; 4) manner of handling; 5) nature
of the material; 6) objective of the activity; and 7)
location of the activity.57. 58
Liability Considerations
Because some secondary materials and all waste
residues are still considered by EPA to be hazardous
and regulated under RCRA Subtitle C unless they
meet the delisting criteria of'40 CFR 260.22, a
generator that recycles its wastes is subject to the
same type (though perhaps not the same degree) of
liability risks as a generator that treats and land
disposes of its wastes without first recycling.59 Thus,
a generator recycling and disposing on-site must be
concerned about liability resulting from improper
disposal of the residue. For a generator recycling and
disposing off-site, liability could result under common
law, RCRA, or CERCLA if the transporter, recycler, or
disposal facility mishandles the waste in a way that
results in an unauthorized release of the waste into
the environment.
Furthermore, courts have made it clear that a
generator must monitor the activities of future
possessors of its wastes, including recyclers, in order
to minimize the risk of liability. This is true whether
ownership of the waste is transferred from the
generator to the transporter, recycler, or disposal
company.so or the transaction between generator and
recycler is characterized as a "sale" of commercial
goods rather than an "arrangement" for disposal
under CERCLA I07(a)(3).6i
Other Considerations
In addition to liability considerations, a generator may
be required to obtain permits in order to recycle, an
often costly and time-consuming process. A generator
shipping wastes off-site to be recycled must comply
with the applicable requirements of 40 CFR Parts 262
and 263 and the notification requirements of RCRA.
3010.62 Generators recycling on-site (as well as any
owner or operator of a recycyling facility) must also
comply with all applicable requirements of 40 CFR
Sections 265.71 and 265.72 and RCRA 3010
notification requirements. If the recyclable materials
are stored prior to recycling, all applicable provisions
at 40 CFR Parts 264 (subparts A-L), 265 (subparts A-
L), 266, 270, and 124 and RCRA 3010 notification
requirements must be followed.63
Furthermore, logistical considerations may prevent a
generator from recycling wastes. For example, even if
the waste is technically recyclable, it may be difficult
to accumulate sufficient quantities on-site to make the
process economically attractive, or it may be difficult
to synchronize generator and recycler needs.
Option Three: Treatment and Land Disposal
A third option available to a hazardous waste
generator is to treat the waste to meet RCRA 3004
treatment standards and then dispose of the residual
waste in a RCRA permitted landfill or other disposal
facility (or obtain a variance from the land disposal
restrictions and dispose of the waste untreated). If the
waste volume and/or toxicity has not been reduced
through any intermediate processing techniques prior
to treatment and disposal (i.e., the waste is shipped
directly from its point of generation to the TSD
facility), this disposal method can be the most
expensive and liability-prone option.64 Generators who
are responsible for the disposal of hazardous wastes
or waste residues must therefore make efforts to
minimize RCRA, CERCLA, and common law liability
risks. Some of these protective steps are discussed
later in this paper.
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Liability Considerations
Statutory Liability
RCRA - Under RCRA 7003, codified at 42 U.S.C.
6973, the government is authorized to initiate
injunctive action or issue remedial orders when past
or present handling, storage, treatment, transportation,
or disposal of any solid or hazardous waste may
present an imminent and substantial endangerment to
health or the environment.
The HSWA 1984 amendments to this section make it
clear that past and present generators that have
contributed to the site are among those potentially
liable. Similarly, courts have interpreted 7003 to apply
retroactively to past and present generators, and
where the injury occurring is indivisible, to impose
joint and several liability. In addition, liability can be
strictly imposed without fault or negligence on the part
of the generator; to establish a prima facie case of
liability, the government need only show: 1) that the
conditions at the site present an imminent and
substantial endangerment; 2) that the endangerment
stems from the handling, storage, treatment,
transportation, or disposal of any solid or hazardous
wastes; and 3) that the defendant has contributed or
is contributing to such handling, storage, treatment,
transportation, or disposal.65 Thus, a non-negligent
generator could be held strictly and solely liable under
RCRA 7003 for releases or spills caused by its
transporter or treatment and disposal facility.
In addition, RCRA 3008(d), codified at 42 U.S.C.
6928, imposes criminal penalties upon any person
who knowingly transports or causes to be transported
or knowingly treats, stores, or disposes of any RCRA
hazardous waste without a permit or in noncompliance
with the manifest system. Violation of this section can
result in fines of up to $50,000 per day of violation or
imprisonment of two to five years. In one case where
a generator was found guilty of knowingly shipping
wastes to an unlicensed recycling facility, the court
concluded that knowledge does not require certainty,
and that a defendant acts knowingly if he willfully fails
to determine the permit status of the facility.66
CERCLA - Generators can also be held liable for
corrective action and response costs under CERCLA
Sections 106 and 107.67 Section 106 allows the
government, through the use of administrative orders
and judicial relief, to abate an "imminent and
substantial" threat to the public health which results
from an actual or threatened release of a hazardous
substance. CERCLA 107 allows the government to
recover response costs for cleanup of wastes from
four classes of defendants: current owners of a
disposal site, past owners of a disposal site,
generators who arrange for disposal at a site, and
transporters of waste to a site from which the waste is
released or is threatened to be released.
Courts have interpreted these provisions of CERCLA
broadly, and have determined that liability under them
is strict, joint, and several. Furthermore, the proof of
causation needed to impose liability is minimal.68,69
Once the requisite nexis is established, the burden of
proof is on the defendant to show that it meets one of
the affirmative defenses set out in CERCLA 107(b).
The government therefore is not required to fingerprint
a generator's waste (i.e., prove that that particular
generator's waste caused the damage), but need only
show that the generator disposed of its hazardous
substances at a facility which now contains hazardous
substances of the sort disposed of by the generator
and a release of that or some other type of hazardous
substance causes the incurrence of response costs.70
Because CERCLA 107(a)(3) only requires that the
generator arrange for disposal "at any facility owned
or operated by another party" from which there is a
release, many courts have rejected the notion that a
generator must have chosen the site at which its
wastes are actually disposed in order to incur
liability.71 Thus, a non-negligent generator can be held
liable under CERCLA 106 and 107 for releases
caused by the actions of its transporter or treatment
and disposal facility (even if it is not a facility that the
generator selected).
Furthermore, because the person arranging for
disposal is not required under CERCLA to actually
own or possess the hazardous waste or the facility
from which it is removed for disposal, courts have
interpreted the term "person" to include both the
generator corporation and individual employees of the
generator corporation. Thus, those persons that
actively exercise control over the place and manner of
disposal can be potentially liable under the
statute.72,73
Common Law Liability
A plaintiff bringing suit against a generator for injury
resulting from improper management or disposal of
hazardous wastes could base the claim on five
possible common law theories: negligence, trespass,
nuisance, strict liability, and vicarious liability.74
Because of the difficulties of proving causation under
negligence, the limitation of trespass solely to injuries
to land, and the burden of establishing the equities in
one's favor under nuisance law, a plaintiff is most
likely to be successful under theories of either strict or
vicarious liability.
Under strict liability, a generator could be held liable
on the ground that it is making a "non-natural" use of
its land (the Rylands approach) or on the ground that
it is engaging in an "abnormally dangerous" activity
(the Restatement approach). Courts that have held
generators liable under a strict liability theory have
analogized to strict products liability and have justified
it on the basis that the generator economically
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benefits from the activity and therefore should bear
the costs of injury.75 Before a successful claim can be
made under strict liability, however, the plaintiff must
show that the generator's activity is inherently or
abnormally dangerous and prove a causal connection
between the generator's activity and the harm
incurred76.
Under a vicarious liability theory, a plaintiff could claim
that the generator should be held liable for improper
management of wastes by its transporter or disposal
facility because the generator arranged for the
disposal. The plaintiff would have to prove, however,
that the work contracted for between the generator
and the transporter or disposal facility is inherently or
intrinsically dangerous or likely to result in a nuisance
or a trespass77.
Recommendations
Because a generator faces continuing liability risks for
hazardous waste releases, it should attempt to
minimize these risks when dealing with transporters,
recyclers, and treatment, storage and disposal (TSD)
facilities. Some practical suggestions follow:
First, generators should exercise due care in selecting
a transporter, recycler, or TSD facility. In choosing a
transporter, the generator should verify permits,
licenses, and equipment and require the transporter to
post a security or performance bond. In choosing a
recycler or TSD facility, the generator should be
satisfied that the facility has the capacity to handle its
waste, has the proper state and federal permits, is in
good standing with the appropriate environmental
agencies, and has sufficient insurance coverage. A
generator may also want to conduct an on-site
evaluation of the plant and talk with other customers
about their experiences.
Second, a generator should monitor its wastes. With
respect to transporters, a generator should make sure
that it receives a manifest copy to ensure that the
waste has reached the proper disposal facility. In
addition, some companies periodically follow their
transporter's vehicle to make certain that the waste is
actually delivered to the proper destination^. With
respect to a recycler or TSD facility, monitoring
means ensuring that permits and insurance coverage
are current and verifying that wastes are treated to
meet the land disposal treatment standards prior to
disposal.
Finally, generators should protect themselves through
indemnity agreements with transporters, recyclers, or
TSD facilities. Any contract for transport, treatment, or
disposal should precisely state that the indemnitor
(transporter, recycler, or TSD facility) will indemnify
the generator against liability resulting from strict
liability or the indemnitor's negligent actions, or from
failure to comply with statutes, ordinances, regulations
(including treatment standards), or permit conditions.
In accepting an indemnity, of course, the generator
should investigate the indemnitor's financial
resources, to ensure that the indemnity is of value. In
addition, the generator should consider a contract
provision requiring the transporter or facility to carry
environmental impairment insurance for the protection
of both parties (waiving subrogation) and naming the
generator as an additional insured partySO.
Other Considerations
Obtaining an Exemption or Variance From the Land
Disposal Restrictions
A generator could apply for an exemption or variance
from the land disposal treatment standards and
continue to dispose of its wastes untreated. In order
to obtain an exemption, a generator must demonstrate
to a reasonable degree of certainty that no hazardous
constituents will migrate from the disposal unit. Initially
EPA proposed that the applicant need only show that
any migration from the disposal site would be at
concentrations that did not pose a threat to human
health and the environment. The agency changed its
position in promulgating its final rule, however, and
now requires a showing of no migration whatsoever.
The agency has acknowledged that the new no
migration standard is more stringent, and it expects
relatively few cases in which the demonstration will be
made81.
Alternatively, a generator could obtain a variance from
the land disposal restrictions by showing that it has
entered into a binding contract to construct or
otherwise provide alternative capacity that cannot
reasonably be made available by the applicable
restriction date due to circumstances beyond the
generator's control. Such a solution is temporary,
however, as an extension cannot be granted beyond
two years. Furthermore, treatment, storage, and
disposal facilities may be reluctant to accept wastes
purported to be exempt from the treatment standards
because they cannot easily verify that such is the
case. A final consideration in obtaining a variance
from EPA is that state law may impose more stringent
treatment standards or even prohibit variances
altogether based on regional capacity determinations.
Off-Site Treatment and Disposal: Capacity Limitations
A generator treating and disposing of wastes off-site
will have to consider short-term and perhaps even
permanent treatment capacity shortages that have
resulted from implementation of the land disposal
restrictions and siting and permitting difficulties
encountered by new facilities. Such shortages, along
with more stringent design and construction standards
for RCRA-approved landfills, are likely to drive up the
costs of treatment and disposal significantly82.
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EPA has already identified shortages of treatment
capacity for solvent and dioxin wastes. For solvents,
the agency estimates a shortfall of approximately 378
million gallons per year for wastewater treatment
capacity and 42.7 million gallons per year for
incineration^. The agency concluded that there are
currently four wastewater treatment facilities and 12
commercial incinerator facilities available to accept
solvent wastes84-85.
Whether capacity shortages will continue into the
future depends upon how quickly the marketplace can
install more capacity to respond to the land disposal
restrictions and at what cost. Two significant market
impediments to the siting of new facilities are public
opposition to the construction of new waste sites and
the financial liability requirements applicants must
meet in order to secure a TSDF permit. Public
concern about the risks posed by hazardous wastes
creates a "not in my community" syndrome, and
leads to opposition against local transportation and
disposal of the wastes. Typically such resistance is
extremely difficult to overcome.
Furthermore, assuming that a facility receives
construction approval, a TSDF operator must comply
with extensive RCRA permit requirements such as
ground-water monitoring, minimum technological
construction requirements, preparedness and
prevention requirements, recordkeeping and reporting
requirements, and post-closure monitoring re-
quirements. The permit process is costly and usually
takes several years to complete. Applicants are also
subject to the corrective action provisions of RCRA
3004 (u) and (v), which require corrective action for all
releases of hazardous waste constituents from any
unit at a TSD facility seeking a permit regardless of
when the release occurred.
Finally, a TSDF applicant must demonstrate financial
responsibility for bodily injury and property damage
arising from both sudden accidental and nonsudden
accidental occurrences. This requirement can be
satisfied through liability insurance, corporate
guarantee, or a combination of the two.86 EPA has
concluded that units at over 1,000 of 1,551 land
disposal facilities have lost RCRA interim status
because of their inability to certify compliance with
these financial responsibility requirements.87 In fact,
unavailability of adequate insurance coverage is the
primary reason that TSDF owners and operators are
unable to comply. Because insurers consider
pollution-related risks to be so high, they have
decreased the types of insurance available to TSDF
owners and operators while substantially raising the
costs of obtaining insurance. Policy premiums "have
increased 50 to 300 percent, and many companies
have difficulty obtaining coverage at all. Coverage for
environmental claims (at least for those based on
sudden and accidental releases) was previously
available to TSDF owners and operators to protect
themselves in part from third party and government
claims. However, such coverage is now generally
unavailable.88
The above factors-public opposition to new TSD
facilities, costly and time-consuming permit
requirements, and difficulties in obtaining adequate
liability insurance-will combine to further prolong the
treatment and disposal capacity shortage that
hazardous waste generators are currently
experiencing.
On-Site Treatment and Disposal: Permitting Difficulties
A generator may consider on-site treatment and
disposal of wastes for the following reasons: 1) to limit
transportation and disposal costs; 2) to reduce the risk
of incurring cleanup costs under RCRA or CERCLA
for a hazardous waste release; and 3) to assure future
treatment and disposal capacity. While on-site
treatment and disposal may be an economically
feasible alternative, a generator applying for an on-site
permit will face the same difficulties as commercial
TSDF applicants, including public opposition and
substantial permitting and financial responsibility
requirements.
References
1. 42 U.S.C. 6901 etseq.
2. 42 U.S.C. 9601 et seq.
3. 42 U.S.C. 6902(b).
4. The disposal restrictions apply prospectively to
persons who generate or transport hazardous
waste and to owners and operators of
hazardous waste treatment, storage, and
disposal facilities, including both interim status
and permitted facilities. (51 Fed. Reg. 40638
[Nov. 7, 1986], to be codified at 40 CFR
268.1.) Land disposal is defined to include
placement in a landfill, surface impoundment,
waste pile, injection well, land treatment facility,
salt dome formation, salt bed formation,
underground mine or cave, concrete vault, or
bunker intended for disposal purposes, or
placement in or on land by means of open
detonation and open burning where the
residues continue to exhibit one or more
characteristics of hazardous waste. (51 Fed.
Reg. 40638 [Nov. 7, 1986], to be codified at 40
CFR 268.2(a).)
5. RCRA 3004(d),(e),(g); 42 U.S.C. 6924
(d),(e),(g).
6. RCRA3004(m).
7. Determinations regarding injection well and
surface impoundment disposal are treated
differently. Under RCRA 3004(f), EPA is to
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8.
9.
review deep well injection methods for liquid
hazardous wastes, solvents, and dioxins by
August 1988. Under RCRA 3005(j), wastes
treated in surface impoundments are exempted
from the land disposal if the impoundments
meet the minimum technological requirements
of RCRA 3004(0) (with limited exceptions) and
the treatment residues which are hazardous are
removed for subsequent management within
one year of the entry of the waste into the
surface impoundment.
51 Fed. Reg. 40642 (Nov. 7, 1986), to be
codified at 40 CFR 268 Subpart D; 52 Fed.
Reg. 25760 (July 8, 1987), to be codified at 40
CFR 268.4.
For a schedule of specific listed wastes to be
evaluated, see 40 CFR Subpart B,
268.10-.13.
10. RCRA3004(d)(1),(e)(1), and (g)(5).
11. The variance granted by EPA for dilute solvent
wastes is currently being challenged by the
Hazardous Waste Treatment Council (HWTC)
and other groups (HWTC v. EPA, CADC No.
86-1657). These groups claim that EPA's
interpretation of the variance provisions, which
allows exempted wastes to be disposed of in
RCRA-approved facilities, will allow these
wastes to be disposed of in old units that do
not have to meet the minimum technological
requirements under RCRA 3004(0) for new
facilities. Plaintiffs contend that such an
interpretation will penalize companies that have
made big investments to comply with the
minimum technological requirements and are
currently able to accept the exempted wastes.
12. 51 Fed. Reg. 40579 (Nov. 7, 1986), to be
codified at 40 CFR 268.30.
13. 51 Fed. Reg. 40605 (Nov. 7, 1986).
14. 51 Fed. Reg. 40639, (Nov. 7, 1986), to be
codified at 40 CFR 268.5.
15. 51 Fed. Reg. 40642-43 (Nov. 7, 1986), to be
codified at 40 CFR 268.50.
16. 51 Fed. Reg. 40580 (Nov. 7, 1986).
17. 51 Fed. Reg. 40607 (Nov. 7, 1986).
18. 51 Fed. Reg. 40610 (Nov. 7, 1986).
19. 51 Fed. Reg. 40639" (Nov. 7, 1986), to be
codified at 40 CFR 268.3.
20. 51 Fed. Reg. 40641 (Nov. 7, 1986), to be
codified at 40 CFR 268.7(a).
21. 51 Fed. Reg. 40641 (Nov. 7, 1986), to be
codified at 40 CFR 268.7(a)(1).
22. The certification must be signed by an
authorized representative and must state the
following: "I certify under penalty of law that I
personally have examined and am familiar with
the waste through analysis and testing or
through knowledge of the waste to support this
certification that the waste complies with the
treatment standards specified in 40 CFR Part
268 Subpart D. I believe that the information I
submitted is true, accurate and complete. I am
aware that there are significant penalties for
submitting a false certification, including the
possibility of a fine and imprisonment." (51
Fed. Reg. 40641 [Nov. 7, 1986], to be codified
at 40 CFR 268.7(a)(2)(ii).)
23. 51 Fed. Reg. 40641 (Nov. 7, 1986), to be
codified at 40 CFR 268.7(a)(2) and (3).
24. The certification must be signed by the treater
or his authorized representative and must state
the following: "I certify under penalty of law that
I have personally examined and am familiar with
the treatment technology and operation of the
treatment process used to support this
certification and that, based on my inquiry of
those individuals immediately responsible for
obtaining this information, I believe that the
treatment process has been operated and
maintained properly so as to achieve the
treatment standards of the specified technology
without dilution of the prohibited waste. I am
aware that there are significant penalties for
submitting a false certification including the
possibility of fine and imprisonment." (51 Fed.
Reg. 40641 [Nov. 7, 1986], to be codified at 40
CFR 268.7(b)(2)(i).)
51 Fed. Reg. 40641 (Nov. 7, 1986), to be
codified at 40 CFR 268.7(b).
25.
26.
27.
28.
51 Fed. Reg. 40641 (Nov. 7, 1986), to be
codified at 40 CFR 268.7(c).
RCRA 3008(a)(3); 42 U.S.C. 6928(a)(3).
RCRA 3002; 42 U.S.C. 6922.
29. 51 Fed. Reg. 35190,35193 (Oct. 1, 1986).
30. Small quantity generators must certify that a
good faith effort has been made to minimize
waste generation and to select the best waste
management method that is available and
affordable. (51 Fed. Reg. at 35193 [Oct. 1,
1986]).
31. RCRA 3005, 42 U.S.C. 6925.
32. U.S. Environmental Protection Agency, Office
of Solid Waste. Report to Congress on
minimization of hazardous waste, Oct. 1986, p.
6.
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33. Id. at pp. iii-iv.
34. Id. at pp. iv, 13-14.
35. Id. at pp. 5-6.
36. See, e.g., 98th Cong., 1st Sess. 66. Senate
Environment and Public Works Committee
Report No. 284, 1983.
37. 50 Fed. Reg. 28734 (July 15, 1985).
38. EPA Report at pp. xxiii, 77.
39. Two senate bills (S.1331 and S.1429) have
been introduced in order to provide such
assistance.
40. EPA Report at pp. xxiii-iv.
41. Other groups are in strong support of such
recommendations. See, for example, OTA
Report, From Pollution to Prevention: A
Progress Report on Waste Reduction, June
1987; Biden, A New Direction for Environmental
Policy: Hazardous Waste Prevention, Not
Disposal, 17 ELR 10400, 10402, (October
1987). In addition, some states are considering
mandatory reductions. For example, a bill
pending in Massachusetts would require
companies to reduce their total inventory of
hazardous wastes by 15 percent each year. (18
Evt. Rptr. 1588 [10-23-87]).
42. EPA Report at pp. xxiv-xxv.
43. EPA Report at p. 67.
44. EPA Report at p. 7.
45. Of course, any company that uses hazardous
substances must continue to comply with
applicable provisions of federal and state law
governing the use of hazardous substances,
including, inter alia, the reporting and
notification requirements of Title III of the
Superfund Amendments and Reauthorization
Act of 1986 (SARA) and the Hazard
Communication Standard (HCS) of the
Occupational Safety and Health Act (OSHA),
and similar statutory provisions.
46. Regulatory barriers in other contexts are also
not uncommon. In some air pollution control
districts, for example, even process changes
resulting in a net reduction in air emissions may
still trigger new source review, including the
requirements for purchasing offsets and the
installation of Best Available Control
Technology. See, e.g., South Coast Air Quality
Management District Regulation XIII.
47. EPA Report at pp. x-xii.
48. .40CFR261.1(b)(7).
49. 40CFR261.1(c)(5).
50. 40CFR261.1(c)(4).
51. 50 Fed. Reg. 619 (Jan. 4, 1985).
52. 50 Fed. Reg. 618-19, 664 (Jan. 4, 1985).
53. 40 CFR261.2(e).
54. 26 ERG 1345 (July 31, 1987).
55. Id. at 1352.
56. 53 Fed. Reg. 519 (Jan. 8, 1988).
57. It should be noted that the proposed
amendments, when finalized, will be applicable
only in states that do not have RCRA interim or
final authorization. In authorized states, the
amendments will not become effective until the
state revises its program to adopt equivalent
requirements under state laws. Furthermore,
authorized states are not obligated to modify
their RCRA programs because the
amendments reduce the scope of the federal
program and make it less stringent; states are
only required to adopt new federal
requirements that are more stringent. RCRA
authorized states therefore have the option of
retaining the more stringent 1985 recycling
requirements. (See 53 Fed. Reg. at 528 [Jan.
8, 1988]).
58. 53 Fed. Reg. 526 (Jan. 8, 1988); 50 Fed. Reg.
654 (Jan 4, 1985).
59. In most circumstances, recycling will have a
liability advantage over treatment and disposal
because the residue resulting from recycling
will be lower in volume than unrecycled waste.
Furthermore, the residue may be less haz-
ardous than its waste predecessor and
therefore easier to delist, or could be in a form
that is easier to delist, or could be in a form
that is easier to dispose of and more resistant
to leaching. In other situations, however, a
recycling or treatment process could concen-
trate the hazardous constituents of a waste,
making the waste more toxic and difficult to
dispose of.
60. U.S. v. Wade, 577 F. Suppl. 1326 (E.D. Pa.
1983).
61. U.S. v. A&F Materials, 582 F. Supp. 842, 845
(S.D. III. 1984) - spent caustic solution sold by
generator to highest bidder; U.S. v. Ward, 618
F. Supp. 884, 895 (E.D. N.C. 1985) - sale of
PCBs by generator to a transporter; N.Y. v.
General Electric Co., 592 F. Supp. 291, 297
(N.D. N.Y. 1984) - generator sold used
transformer oil to a dragway to be used as
dragway owner saw fit.
62. 40CFR261.6(b).
63. 40 CFR 261.6(c)(1) and (2).
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64.
65.
66.
68.
This would obviously not be the case if the
generator could delist its waste after treatment
and dispose of it under RCRA Subtitle D. Then
direct treatment and disposal could be an
attractive option from both an economic and
liability standpoint. RCRA delisting may not
protect the generator from CERCLA liability,
however.
Sec, e.g., U.S. v. Northwestern Pharmaceutical
and Chemical Co., 810 F. 2d 726 (8th Cir.
1986); U.S. v. Bliss, 667 F. Supp. 1298 (E.D.
Mo. 1987); U.S. v. Conservation Chemical Co.,
619 F. Supp. 162 (W.D. Mo. 1985).
U.S. v. Hayes International Corp., 786 F. 2d
1499, 1504 (11th Cir. 1986) citing Boyce Motor
Lines V. U.S., 342 U.S. 337 (1952).
67. 42 U.S.C. 9606-07.
Congress affirmed the courts' interpretation of
CERCLA in the legislative history to the
Superfund Amendments and Reauthorization
Act of 1986 (SARA). (See, e.g., H.R. Rep. No.
253, 99th Cong., 1st Sess., pt. 3 at 15 [1985]
[Judiciary Committee]).
69. See, e.g., U.S. v. Wade, 577 F. Supp. 1326
(E.D. Pa. 1983); U.S. v. Price, 577 F. Supp.
1103 (D. N.J. 1983); U.S. v. Chem-Dyne Corp.,
572 F. Supp. 802 (S.D. Ohio 1983); U.S. v.
Northwestern Pharmaceutical and Chemical
Co., 810 F. 2d 726 (8th Cir. 1986); U.S. v. A&F
Materials Co. Inc., 578 F. Supp. 1249 (S.D. III.
1984); U.S. v. Conservation Chemical Co., 619
F. Supp. 162 (W.D. Ma. 1985).
70. Wade at 1333. See Also Violet v. Picillo, No.
83-0787P, slip op. (D.R.I. Nov. 10, 1986); U.S.
v. Miami Drum Services, Inc., No. 85-0038, slip
op. (S.D. Fla. Dec. 12, 1986).
71. See Wade at 1333 n. 3; Picillo at 8;
Conservation Chemical Co. at 234; U.S. v.
Ward, 618 F. Supp. 884, 895 (E.D. N.C. 1985).
72. See U.S. v. Northwestern Pharmaceutical &
Chemical Co., 579 F. Supp. 823, 847 (W.D.
Mo. 1984), aff'd, 810 F. 2d 726 (8th Cir.
1986) - vice president as well as president of
the facility, held liable; U.S. v. Bliss, 667 F.
Supp. 1298 (E.D. Mo. 1987) - waste broker
held liable; Jersey City Redevelopment Authority
v. PPG Industries, 655 F. Supp. 1257 (D. N.J.
1987) - defendant company within the scope oi
CERCLA 107 when it arranged to sell mud from
its property as fill even though company was
unaware that the mud was contaminated with
hazardous chromium.
73. The New Jersey court did note that lack of
knowledge could possibly be an affirmative
defense.
74. See J. DiBenedetto, General liability under the
common law and federal and state statutes. 39
Bus. Calc. 611, 1984.
75. See, e.g., City of Bridgeton v. British Petroleum
Oil, Inc., 369 A. 2d 49 (N.W. Super. Ct. Law
Div. 1976); State of New Jersey Dept. of
Environmental Protection v. Ventron Corp., 463
A. 2d 893 (N.J. 1983).
76. DiBenedetto at 621.
77. DiBenedetto at 622.
78. See R.T. Murphy. Generator responsibilities in
selecting treatment, storage, and disposal
services. 39 Bus. Law. 309, 1983.
79. Murphy at 313.
80. See C.F. Lettow and J.T. Byam. Generator-
disposer indemnity agreements. 39 Bus. Law.
315, 1983.
81. 51 Fed. Reg. 40578 (Nov. 7, 1986).
82. EPA estimates that these new requirements
have already pushed the price of land disposal
from $10 to $15 per metric ton in the early
1970s to $240 per metric ton. EPA Report at
15.
83. 51 Fed. Reg. 40614 (Nov. 7, 1986).
84. Id.
85. One recent development that may help to
alleviate capacity problems is the new mobile
treatment unit (MTU) permit program, which
was finalized by EPA in early 1988. 52 Fed.
Reg. 20914 (June 3, 1987). An MTU permit
would allow commercial companies to treat
wastes at the generator's site rather than
requiring transport of the wastes to a treatment
facility.
86. RCRA 3004(a)(6) and 3005(e)(2); 40 CFR
264.147(a) and (b).
87. EPA Report at 23.
88. EPA Report at 22-23.
30
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Chapter 5
Minimization of Process Equipment Cleaning Waste
Carl H. Fromm
Srinivas Budaraju
Susanne A. Cordery
Jacobs Engineering Group, Inc.
HTM Division
Pasadena, CA 91101
The waste associated with cleaning of process
equipment is probably a significant contributor to the
total waste volume generated by industry. This paper
addresses the following aspects related to equipment
cleaning waste generation:
Review of reasons for cleaning process
equipment.
Reduction of cleaning frequency.
Reduction of quantity and toxicity of cleaning
waste. »
Costs associated with cleaning.
Equipment cleaning techniques, media, and their
applications are reviewed. Reduction of cleaning
frequency is addressed in terms of inhibition of fouling
through proper equipment design and operation,
maximization of equipment dedication, proper
production scheduling, and avoidance of unnecessary
cleaning. When cleaning has to be performed, the
quantity and toxicity of the resulting waste can be
minimized by reducing clingage, decreasing the
amount of cleaning solution, choosing a less toxic
cleaning solution, reusing cleaning solution, and other
approaches. Application examples are given to
illustrate each approach.
The current costs of waste disposal and treatment,
regulatory pressure, and concerns about legal
liabilities have been forcing U.S. industries to
scrutinize their hazardous waste generation
practices.1 A primary objective of these efforts has
been to minimize waste generation, i.e., to reduce the
quantity and toxicity of the waste.
Of the many industrial waste-generating operations,
process equipment cleaning (PEC) is nearly universal
in its application, as it is practiced in all segments of
manufacturing industry. PEC is of particular impor-
tance for discrete processes such as batch reactions,
compounding, surface coating operations, etc. This is
because the cleaning frequency for discrete proces-
ses is generally much higher than for continuous
processes. However, this does not mean that cleanup
wastes from continuous processes can be ignored.
Disposal of sludges from cleaning of heat exchanger
fouling deposits, for example, is often of concern to
the operators of petroleum refining, petrochemical,
and chemical process facilities.
The intent of this chapter is to review basic waste
minimization strategies applicable to cleaning
operations. A structured classification of strategies will
be provided in the form of a prototype checklist which
can be used to help focus and plan a concerted
attack on waste.
Why Equipment is Cleaned
Equipment cleaning is a maintenance function typically
performed for the following reasons:
To restore or maintain the operating efficiency of
equipment, e.g., to restore adequate heat transfer
rate and low pressure drop in heat exchangers.
To avoid or limit product contamination, e.g.,
when a paint mix tank needs to be cleaned
between batches of varying paint formulations.
To minimize corrosion and extend equipment
lifetime.
To allow for inspection and repair of equipment.
To improve appearance (exterior surfaces only).
The need for cleaning is a direct consequence of
deposits formed on the surfaces exposed to the
process environment. Some of the major routes and
origins of deposit formation are summarized in Table
5-1 along with descriptions and some examples.
Understanding how and why the deposits are formed
31
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is a critical first step in any waste minimization effort.
It is an especially important aspect for equipment and
process designers, because the need for equipment
cleaning can often be reduced or eliminated through
design modifications at minimal expense during the
design stage.
Table 5-1. Typical Routes and Origins of Deposit
Formation in Process Equipment
Route/Origin
Description
Crystallization
Sedimentation
Chemical reactions
arid polymerization
High temperature
coking
Corrosion
Bactonal growth
(btfouling)
Clingage (of
importance to solvent
cleaning applications)
Major problem in evaporators and
crystaliizers (e.g., very frequent in food
processing).
Major problem in petroleum refinery crude
unit desalters and oil storage tanks. Also
present in cooling tower basins.
Buildup on the internal reactor surfaces is
often encountered (e.g., allyl chloride
synthesis). Also of importance in crude oil
storage tanks.
Carbonaceous material depositing on walls
of furnace tubes (e.g., furnace for ethylene
chloride pyrolysis).
Common problem in heat exchangers in
chemical and allied product industries.
Major problem on cooling-water-side of
heat exchangers in electric power
production
Residual coat of process liquid left after
drainage; major problem in reactors and
mixers in the paint manufacturing industry
and generally in all high-viscosity liquid
transfer operations
A common-sense approach to minimizing waste from
equipment cleaning operations is to pose and answer
the following questions:
Why is the deposit present?
How can cleaning be curtailed or avoided (i.e.,
cleaning frequency reduced)?
When cleaning is necessary, which cleaning
method and medium will generate the least
amount of least toxic waste?
Sections below address major aspects related to the
last two questions.
Reduction of Cleaning Frequency
Generally, the need for cleaning can be reduced or
avoided altogether by the application of the following
measures:
Inhibition of fouling or deposit formation rate.
Maximizing dedication of process equipment to a
single formulation or function.
Proper production campaign scheduling.
Avoidance of unnecessary cleaning.
Inhibition of Fouling
Inhibition of fouling is of particular importance in heat
transfer applications where it can be accomplished
through a variety of means, including use of smooth
heat transfer surfaces, lower film temperatures,
increased turbulence, control of fouling precursors,
and proper choice of exchanger type.
The use of smooth heat exchanger surfaces results in
lowering the adhesion of the deposit or its precursor
to the surface. Application of electropolished stainless
steel tubes in a forced circulation evaporator used in a
black liquor service in a paper mill resulted in a
dramatic reduction of cleaning frequency from once a
week to once a year.2 Smooth non-stick surfaces can
also be provided with Teflon. Teflon heat exchanger
designs are commercially available, as are designs
utilizing Teflon-coated steel. In a separate application,
condensers using Teflon-coated tubes have been
shown to drastically reduce fouling and resist
corrosion while maintaining high thermal efficiency.
The higher cost of material was weighed against
reduced energy cost to show a 69 percent return on
investment in the first year before taxes.s If reduced
cleaning costs were to be added, the Return on
Investment (ROI) would have been higher.
The rate of heat exchanger fouling in a given service
is dependent upon fluid velocity and, quite often, on
film temperature. Film temperature controls the speed
of chemical reactions which result in deposit-forming
compounds while fluid velocity controls the shear rate
at the fluid-deposit interface.
Hence, lowering the temperature of the heating
medium and increasing the fluid velocity (e.g., by
recirculation) can produce a desired reduction of the
fouling rate. An economic trade-off analysis between
the increase in pumping cost and the decrease in the
cost of cleaning and other possible savings appears
warranted in investigations relating the degree of
oversizing to cleaning waste generation. A general
review of thermal and hydrodynamic aspects of heat
exchanger fouling was provided by Knudsen.4
Control of deposit precursors is often an obvious
practical consideration. Proper maintenance of cooling
water quality in open circulating systems is of
paramount importance to water-side heat exchanger
fouling. Control of hardness, pH, corrosivity and
biofouling tendency is accomplished through careful
monitoring of water quality.5 In particular, biocides
added in treatment must propagate the entire cooling
fluid path to be deposited and function at all locations
in the exchanger. Acid feed equipment to maintain the
pH in the non-scaling range of 6 to 7 must be reliable
or else rapid scaling or corrosion problems occur.4
The choice of heat exchanger type can influence
cleaning frequency. For example, spiral plate
32
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exchangers are often specified over other designs in
fermentation plants, owing to the ease of solid
resuspension, absence of pockets, and nonplugging
characteristics. Rod baffle design provides more
effective shell-side turbulence at lower pressure drop
compared to a more conventional segmented baffle
design. Therefore, the rod baffle design can be
expected to exhibit superior shell-side fouling
characteristics.
Slowing down the rate of deposit formation is not
limited to heat exchangers, but also is important for
other types of equipment. For. example, crude oil's
exposure to atmospheric oxygen can cause formation
of gums and resins during long exposure periods
inside storage tanks. The use of floating roof tanks or
inert gas blanketing has been suggested as a way to
reduce tank deposit buildup.6 Similarly, in paint
manufacturing, exposure to air causes formation of
solid films that adhere strongly to the internal surface
of the mixers. This can be avoided ;by using closed
storage and transfer systems, as evidenced by
experience at Ford Motor Company. At Ford, the paint
storage and transfer system was enclosed and
redesigned for full recirculation resulting in less
frequent and easier cleanups and an improvement in
paint quality.7 Other applications of fouling inhibition
include coating of reactor internals with special
chemicals to prevent scale formation. These practices
have been used in the suspension polymerization
process for polyvinyl chloride.8
Maximizing Dedication of Process Equipment
Maximizing dedication of process equipment to a
single process function or formulation will reduce
cleaning frequency, as the frequency of switching to
different formulations will diminish. Maximum
dedication means either converting from a batch to a
continuous process or using the equipment
intermittently just for one formulation.
Historically, the changeover from batch or cyclic to
continuous operations has been common in the
chemical industry, owing to increased product
demand, increased labor costs, and technological
progress. The advantages of the continuous process
over batch include the ease of automation and control
(which minimizes human error leading to inferior
product quality) and lower labor requirements.
The choice between the continuous or batch mode is
governed primarily by production volume and related
trade-offs between capital and operating costs. The
batch process is advantageous in situations where
production volumes are small and product diversity
large. Batch processes have proven advantageous
even for certain large volume products, such as
neoprene rubber and phenolic resins, where
continuous alternatives were developed but failed to
find wide application.9>1o
Dedicating a piece of equipment to a single
formulation in the batch process means that the
equipment remains dormant between individual
production campaigns. Cleaning after each campaign
can be avoided, provided that materials left in
equipment do not deteriorate with time or corrode the
internal parts. Also, the cost penalties associated with
equipment under-utilization must be outweighed by
cleaning costs incurred when the equipment is used
with more than one formulation.
Proper Production Scheduling
Proper production scheduling is a commonly-invoked
method to decrease cleaning frequency. Equipment
utilization strategies and the resulting production
schedules should be derived through optimization
analysis, where the objective is to meet the desired
production goals with due consideration of such
constraints as available equipment, cost of
turnaround, labor availability, storage, etc. Meeting
production goals is to be accomplished with minimum
cost, which includes minimization of cleaning
frequency. A general review of optimum strategy
formulation was given by Peters and Timmerhaus.11
However, in a typical situation a formal optimization
analysis is not often used. Rather, a common-sense
approach to production scheduling is used based on
trial-and-error preparation of production bar charts. To
reduce cleaning waste, it is generally desirable to
schedule long campaign runs, as opposed to short
and more frequent runs. Production schedulers now
must be aware of the current waste disposal costs, an
aspect that previously could have been ignored.
Avoidance of Unnecessary Cleaning
Avoidance of unnecessary cleaning should be one of
the goals of waste minimization audits. At times,
equipment cleaning is performed routinely with little or
no consideration of the rationale for the cleaning
activity. An actual case is known where a ball mill was
used periodically to wetgrind a certain powder. The
ball mill with corrosion-proof internal parts was totally
dedicated to the same formulation, a stable mixture of
inorganic powders. Yet the ball mill was cleaned after
each use for no apparent reason. Upon questioning,
the only justification provided was that the other
nondedicated ball mills at the facility were cleaned
after every use.
Reduction of Quantity and Toxicity of
Cleanup Waste
When cleaning has to be performed, it should be
performed effectively with minimal generation of
waste. Typical considerations include the choice of
cleaning medium, cleaning technique, and waste
disposal option. A brief overview of these choices
33
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(with the exception of waste disposal) is provided in
the following paragraphs.
A distinction can be made between chemical and
mechanical cleaning. Chemical cleaning requires the
use of substances such as those shown in Table
5-2, which are employed to chemically attack the
deposits and render them either solvent or water-
soluble. The basic reaction types include oxidation,
reduction, chelation, or conversion of insoluble oxides
into soluble salts. Cleaning formulations also include
surfactants to lower surface tension of solution to
allow for faster penetration and breakup of deposits.
Physical or mechanical cleaning relies on breaking the
adhesion of the deposit to a surface using mechanical
devices, such as scrapers, squeegees, rags, drag
lines, "pigs," lances, or through the use of high
velocity water jets (hydroblasting). Often mechanical
and chemical cleaning are combined, e.g., when high
velocity jets are employed with caustic solutions to
attack deposits in paint mix tanks.
According to a classification developed by Loucks,12
six separate cleaning techniques are distinguished:
Fill-and-empty technique.
* Circulation technique.
Flow over technique.
Gas propel technique.
Process simulation technique.
Onstream cleaning technique.
In the fill-and-empty technique, a process vessel is
isolated from other equipment and filled with an
appropriate cleaning solution. The solution can be
heated and agitated and after a period of four to eight
hours it is drained. Rinse water or diluted alkali or acid
solutions are then used to remove residual cleaning
chemical. Drained chemicals and subsequent rinses
are reused, treated, recycled, or land-filled depending
on their composition and the availability of disposal
options at the particular site. The method uses large
quantities of chemicals and requires substantial
downtime. It is typically applicable to small vessels,
tanks, or heat exchangers.
In the circulation technique, the vessel is filled with
cleaning solution to an overflow and allowed to stand
for a short time period, after which the solution is
circulated with an auxiliary pump. Fresh make-up
solution can be pumped in if used solution is
withdrawn. In boilers, nitrogen gas is used to provide
agitation for more effective scale removal.
The flow over technique consists of spraying the
solution onto the surface. It is applicable to large tanks
where cleaning by filling or recirculation would require
excessive quantities of cleaning solution. Extra safety
precautions are usually necessary.
The gas propel technique utilizes cleaning agents that
are not overly corrosive at higher temperatures when
steam is used to propel them through the system.
This technique is useful for pipelines, where inhibited
organic acids or chelants are entrained into a flow of
steam which carries the liquid drops and solids debris
through hydraulic obstacles of the system.
The process simulation technique is applied to
equipment that is easily fouled and where spare
parallel units are provided. Fouled equipment is
cleaned by simulated process operation, where the
equipment is isolated, drained of process fluid, and
filled with the cleaning solution using process pumps
Table 5-2. Some Chemical Cleaning Compounds and their Usage
Cleaning Compound Chemical Action
Usage
Remarks
Hydrochloric acid
Suifunc acid
Nilnc acid
Hydrofluoric acid
Suifamic acid
Citric acid
Dissolves most water scales and
corrosion products
Dissolves most corrosion products
Same as HCI
Dissolves silicate deposits
Dissolves calcium salts
Dissolves iron oxides
Causlro soda, soda ash Dissolves oil and grease
Ammonia
Eihytene diamine letra-
acalaie (EDTA)
Forms soluble complexes with
copper ions
Dissolves water scales at alkaline
pHs
Used on boilers, heat exchangers,
pipelines, etc.
Limited use
Used for stainless steel and
aluminum
Used as an additive to HCI (as
ammonium bifluoride)
Used as an additive to HCI
Used mostly to clean boilers;
frequently with added ammonia and
oxidizers
Used to remove oil and grease
before acid cleaning and to
neutralize the acid after cleaning
Used to remove copper from large
boilers
Used for cleaning water systems
without shutdown
Corrosive to steel; temperatures
must be below 175°F
Cannot remove water scales
Cannot be used for copper and
ferrous alloys
Very dangerous to handle
Easy to handle; soluble calcium
salts
Not good for water scale removal
Dangerous to handle
Needs to be handled carefully
Expensive
34
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and controls to maintain flow and temperature. An
example is removal of iron oxide and copper deposits
from high pressure steam generators using
ammoniated EDTA solution.
The on-stream cleaning technique is probably the
most preferable method, as it relies on process fluid
to do the cleaning during normal operation. Often
auxiliary mechanical devices are used along with
additives, such as EDTA or acids to promote deposit
removal. This technique is used for cleaning reactor
jackets, gas compression station engines, heat
exchangers, and other equipment. In-service cleaning
of large circulating cooling water systems is often
done through intermittent pH swing to the acid side of
neutral and back again. Among many mechanical
devices used in conjunction with on-stream cleaning,
one could mention ram valves for rodding out plugged
nozzles and moveable heat exchanger tube inserts
propelled by reversing process fluid.13 In a separate
example, fluidized beds of inert solids (e.g., sand)
were found useful in heat transfer applications
characterized by extreme fouling, such as heat
recovery from geothermal brines. Solid particles
constantly abrade the deposit away from the heat
transfer surface, maintaining high transfer rates.
The choice of cleaning method and media, apart from
cost, should also be based on the following
environmental considerations:
Minimize the amount of cleaning solution used;
Choose the medium ultimately resulting in the
least toxic waste; and
Determine ahead of time how the cleaning waste
is going to be disposed of.
The use of chemical cleaning (e.g., with mineral or
organic acids) results in appreciable quantities of
hazardous cleaning wastes which need to be treated
before disposal. As appropriate treatment facilities are
not available onsite in every case, mechanical
cleaning and on-stream cleaning appear preferable to
chemical cleaning. According to information obtained
from various cleaning contractors, these factors are
gaining recognition as the recent trend has been more
toward hydroblasting and on-stream cleaning and
away from chemical cleaning. This was attributed to
the rising costs of waste disposal and treatment.
When chemical cleaning is unavoidable, the least toxic
medium should be chosen. For example, an alkaline
cleaner would be preferable over a halogenated
solvent. However, if the toxicity of the soil to be
removed is the controlling factor, the cleaning agent
with a higher potential for recovery and reuse should
be used.
An attractive alternative to those cleaning methods
that require disassembly of equipment for cleaning, is
a clean-in-place (CIP) system. The system is
composed of tanks, heat exchangers, filters, pumps,
piping, and instrumentation permanently installed as
an auxiliary system designed to circulate a controlled
inventory of cleaning solution through isolated process
equipment often using spray manifolds or liquid jet
nozzles inside production vessels. The CIP systems
generally reduce the use of cleaning medium. They
are especially effective when coupled with high
velocity automated jet manifolds and staged counter-
current rinsing: an 80 to 90 percent reduction in
aqueous waste was achieved by paint manufacturers
after installing high pressure spray nozzles for tank
rinsing.14 CIP systems are popular in food,
pharmaceutical, and paint industries; however, they
are utilized less frequently in the chemical processing
industry.15
Reuse of cleaning solutions is common in CIP
systems. In general, reuse of cleaning solutions is
highly desirable, especially if they can be utilized as
part of formulation. For example, a considerable
reduction in reactor cleanup waste was achieved by
Borden Chemical where a two-step rinse sequence
was applied to a batch kettle arrangement used for
phenolic resin synthesis. The first rinse used a small
amount of water generating a concentrated stream
which could be recycled to the process. The second
full-volume rinse generated wastewater with a much
lower content of toxic material than a previously used
single rinse method.16 Other examples include reuse
of rinse water from latex tank cleaning as part of latex
formulation in the paint industry17 and use of warm oil
for flushing the deposits out from crude oil storage
tanks in an oil refinery, followed by solids separation
in the slop oil system.18
The preceding sections were concerned with
reduction of cleaning frequency and with the choice of
the least waste-intensive cleaning methodology. There
is a related but independent aspect of cleaning waste
reduction, i.e, reduction of clingage. As defined in
Table 5-1, clingage is the amount of process material
left inside the vessel or other equipment after draining.
In operations involving viscous fluids, such as paint
manufacturing and resin compounding, clingage is an
important consideration as it not only results in waste
which is expensive to dispose of, but also represents
a direct loss of product or raw material.
To reduce clingage, the following measures should be
considered:
Provision of adequate drainage time;
Use of low-adherence surfaces, e.g., fluorocarbon
or electropolished steel;
Use of mechanical wall wipers (dual shaft mixers);
Use of manual wipers or squeegees;
35
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Choice of square, cylindrical, or spherical
geometry to minimize wetted surface; and
Rotation of agitator after batch dumping to reduce
clingage on the blade.
All of the above measures are self-explanatory and do
not require elaboration. Most are practiced extensively
throughout industry. The use of tank linings as a
means of reducing adherence and preventing
corrosion has been addressed by Zolin19 and Keys.20
The use of dual shaft mixers with slow scraper blades
wiping the walls and the bottom of mixing tanks is
common in applications involving viscous liquids.21
Cost of Cleaning
The cost of cleaning can be viewed as being
composed of the following elements:
Direct Costs
Equipment assembly/disassembly.
Cleaning chemicals and supplies.
* Waste treatment and disposal.
* Cleaning labor and supervision.
Cleaning equipment depreciation.
* Utility costs.
Indirect Costs
Planning and scheduling.
Cost of lost production.
* Cost of lost raw materials inventory.
Inspection and testing.
Process equipment deterioration.
Often equipment cleaning is performed by outside
contractors with specialized equipment that assume
the responsibility for hauling away the waste and for
disposing of it properly.
Costs of cleaning vary widely depending upon the
medium, method, and application. Recent inquiries
into the cost of cleaning of heat exchangers
established the compilation of relative heat exchanger
cleaning costs using various contracted services
shown in Table 5-3.
In many cases the cost of cleaning (taken as direct
cost only) is lumped together with other maintenance
costs. As a result, plant management may not know
the actual costs of cleaning, which may impede
management's support for waste minimization efforts.
Table 5-3.
Relative Heat Exchanger
Costs
Method
Relative Cost
Hydroblasting
Podding
Chemical Cleaning:
Without waste disposal
With waste disposal
1.0
4 to 5
0.3 to 3
2.1 to 4
Often, when plant management learns of the true
cost, action to lower cleaning costs is quickly initiated.
Summary
As mentioned in the introduction, the intent of this
chapter is to provide a brief review of techniques,
approaches, and strategies for minimizing equipment
cleaning waste, and to provide a classification scheme
that may serve as an initial guide to those interested
in waste minimization. Such a classification or
summary is provided in Figure 5-1. This serves as a
prototype checklist for addressing all waste
minimization issues in a logical sequence.
Figure 5-1. Waste minimization of equipment cleaning
waste: summary of approaches.
Why is Deposit Present?
Reduce Clean ng Frequency
1.
2.
3.
4.
Inhibition of fouling rate
- smooth heat transfer surfaces
- lower film temperature/higher
turbulence
- control of fouling precursors
- choice of heat exchanger type
Maximize process equipment
dedication
- conversion from batch to
continuous operation
- dedication to single composition
Proper production scheduling
Avoidance of unnecessary cleaning
Reduce Quantity and Toxicity of Waste
1.
2.
Minimize amount of cleaning solution
- high pressure nozzles
- flow-over technique
- on-stream cleaning
- use of CIP systems with stages
or counter-current rinsing
- reuse of cleaning solution
Minimize toxicity of spent cleaning
solutions
- clingage reduction
- mechanical (hydroblasting) over
chemical cleaning
36
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The subject of equipment cleaning is quite diverse as
the function is performed in virtually every industry.
Generalizations presented in this paper must be
translated into site-specific and exacting requirements
in any waste minimization effort.
References
1. League of Women Voters of Massachusetts.
Waste reduction: the untold story. Conference
held June 19-21, 1985 at National Academy of
Sciences Conference Center, Woods Hole, MA.
2. Uddeholm Corporation (Sweden). Technical
brochure on Tubec Tubes and communications
with Avesta Stainless, Inc., Totowa, NJ.
3. Paschke, L.F. Condensing heat exchangers save
heat. Chem. Eng. Progress, pp. 70-74, July 1984.
4. Knudsen, J.G. Fouling of heat exchangers: are we
solving the problem? Chem. Eng. Progress. Feb.
1984, pp. 63-69.
5. Betz Laboratories Inc. Handbook of Industrial
Water Conditioning, 8th Ed., Trevose, PA, 1980.
6. Jacobs Engineering Group, Inc. Alternatives for
hazardous waste management practices in the
petroleum refining industry. EPA-530-SW-172C,
U.S. Environmental Protection Agency,
Washington, DC, 1979.
7. Colleta, V. and Powers, J. Chem P oc. 44(4):20-1,
1981.
8. Cameron, J.B. Lundeen, A.J., and McCulley, J.H.,
Jr. Hydroc. Proc. 59(3):39-50, 1980.
9. Euleco S.P.A. Euleco continuous process:
technical bulletin, 1975.
10. Shell International Research, Inc., Brit. Patent No.
136, 189. Issued Dec. 11, 1968.
11. Peters, M.E. and Timmerhaus, K.D. Plant Design
& Economics for Chemical Engineers, 3rd Edition.
McGraw Hill Book Co., 1980.
12. Loucks, C.M. Boosting capacities with chemicals.
Chem. Eng. (deskbook issue). 80(5):79-84, 1973.
13. Water Services of America, Inc. Superscrubber
technical bulletin, 1985.
14. U.S. Environmental Protection Agency, Office of
Water & Waste Management. Development
document for proposed effluent guidelines, new
source performance standards and pretreatment
standards for the paint formulating, point source
category. EPA-440-1-79-0496, Washington, DC,
1979.
15. Hyde, J.M. New development in CIP practices.
Chem Eng. Progress. 81(1):39-41, 1985.
16. Huisingh, D., et al. Proven Profit from Pollution
Prevention. The Institute for Local Self-Reliance,
Washington, DC, 1985.
17. Riley, J.E. Development document for effluent
limitation guidelines, new source performance
standards for the, tire and synthetic segment of
the rubber processing industry, point source
category. EPA-440-1-74-013A, U.S. Environmental
Protection Agency, Washington, DC, 1974.
18. Barnett, J.W. Better ways to clean crude storage
tanks and desalters. Hydroc. Proc. 60(1):82-86,
1980.
19. Zolin, B.I. Chem. Proc. 47(9):63-5, 1984.
20. Kays, W.B. Construction of Lining for Reservoirs,
Tanks & Pollution Control Facilities. Wiley, New
York, 1979.
21. Myers Mixing Company. Private communication,
1985.
37
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Chapter 6
Source Reduction - Parts Cleaning
Edward A. Rodzewich
Parker and Amchem
Ambler, PA 19002
Introduction
Source reduction of solvents for parts cleaning can
occur in several ways: 1) through complete elimination
of solvents; 2) through reduction of the absolute
quantity of solvents to the minimum; or 3) through the
use of operational procedures such as counterflow
mechanics to control solvent usage.
The possibility and probability of using any of these
techniques for source reduction depends to a great
extent on the degree of cleanliness required and on
the type of surface or combinations of surfaces to be
cleaned.
Complicated or complex-shaped parts must be
cleaned periodically during the course of manufacture.
Cutting oils, machining turnings, and sanding fines are
typical soils to be removed. The purpose of cleaning
for such applications is to provide a surface suitable
for inspection. It is generally not a requirement for
such surfaces to be absolutely free from all soil. The
probability of eliminating solvents from such cleaning
is very high.
If the part is to be painted, corrosion resistance and
adhesion become extremely important. To attain the
maximum quality, all .of the soil, inorganic and organic,
must be removed. The degree of cleaning required is
very high and the probability of eliminating solvents is
lower.
Solvents have been used widely to clean surfaces,
either by themselves or in combination with alkaline or
acidic builders and surfactants. The most commonly
used solvents for parts cleaning are the aromatic and
aliphatic hydrocarbons, ketones, esters, butyl
cellosolve, and various halogenated types such as
methylene chloride or perchlorethylene. These are
very effective for removing greases, fats, and waxes
from metal, glass, and plastic surfaces. The
halogenated solvents such as methylene chloride are
exceptional as paint strippers.
With the increased knowledge of the harmful effects
of exposure to a large number of solvents and the
increased number of regulations governing solvent
emissions and air quality, however, there is a shifting
away from solvent usage in cleaners.
Industry Response to Reduce Solvents
Usage
The automotive industry is so diverse that its needs
can be considered to be representative of all
industries. Thousands of parts from hundreds of job
shops and subcontractors are produced according to
industry specifications. As a result of high buying
power, they are able to exert considerable influence
on their suppliers to use safe and effective chemicals
which are environmentally acceptable. Their use of
the task force concept with several of their suppliers
has resulted in many new products and man-
ufacturing changes, particularly in the area of solvent
reduction. Many of the solvent-free cleaners
developed for the automotive industry are now being
used in a variety of manufacturing industries as well
as*in the home and office.
Since this industry makes use of a wide variety of
cleaning techniques, it will be used as a model for
solvent source reduction. With minor modifications at
best, the products and applications it uses to manage
and control solvent usage are applicable to all
industries.
Cleaning Concept
The most comprehensive definition of a clean surface
is one which is free of all physical and chemical
contamination, is compatible with subsequent
treatments, and results in a quality product.
Subsequent treatments to achieve an ultra-clean
surface condition may include simple inspection for
maintenance and repair, application of conversion
coatings and paint, or electroplating of metals such as
zinc or chromium.
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In many cases, an ultra-clean surface may not be
desirable and may lead to unwanted problems, such
as in-plant rusting during storage or fabrication. A
single part may be cleaned two or three times in the
course of the assembly process primarily for
inspection and maintenance purposes. This type of
cleaning is called in-process cleaning and will be
examined next.
In-Process Cleaning
The starting point for many parts is a coil of metal
such as cold rolled steel, hot dip galvanized steel,
electrogalvanized steel, or aluminum. The parts are
stamped or formed in a central stamping plant and are
subsequently packed in large bins and shipped by rail
or truck to the assembly plants. Typical parts include
frames, leaf springs, hoods, fenders, grills, bumpers,
and hinges.
In the plant, the automobile is assembled in steps.
During this phase many oils and greases are applied
to the parts: they are sanded, spot welded, and in
general there is a lot of handling. Several times during
this assembly operation, the partly assembled unit
must be cleaned to remove the large quantity of soil
adhering to it in order to perform a quality inspection.
Cleaning is accomplished using one- or two-stage
spray washers. Until only recently, the most
commonly used cleaning compositions consisted of
petroleum fractions and emulsifiers mixed with water.
These cleaning compositions were capable of
removing only 90 to 95 percent of the soils and left
the surface with a thin film of solvent that was capable
of providing some degree of temporary, rust-inhibiting
properties. The cleaning baths were prepared by
adding between 10 and 20 percent by volume of the
petroleum fraction concentrate. Cleaning baths were
drained and recharged frequently, on the average of
once a week, depending on the soil loading.
Despite the existence of exhaust fans located at the
entrance and exit ends of the spray washer, solvent
fumes were present in the immediate area where the
personnel were working. The concentration of solvent
odor was enhanced by solvent evaporation from the
film remaining on the units exiting the washer. Skin
contact with the solvent film was inevitable as the
assembly and sanding operations continued.
Oleum Deck
After the unit has been assembled, it is conveyed to
the phosphating stage for final cleaning, phosphating,
and painting. As the unit enters this area, it passes
through the oleum deck where it is sprayed
completely by means of a horseshoe harness using V-
jet or fan-type nozzles. Usually, four to six people,
equipped with soft brushes and/or hand pads routinely
scrub all of the surfaces they can reach. Sometimes
they reach inside the units.
The cleaning compounds used for this application are
similar to those used for in-process cleaning. Since
the degree of cleaning required for phosphating is
considerably higher, however, the cleaner
concentration is also used at a higher level, probably
closer to 20 percent by volume. Buckets are available
for hand cleaning of heavily soiled areas, and contain
the solvent at a 1:1 concentration. The odor, at times,
is intense and cases of eye and skin irritation are
frequent despite the use of protective gloves, clothing,
and solvent masks.
Resolution
The in-process and oleum deck were among the very
first solvent problem areas to be addressed. As the
industry moved from a predominantly steel surface to
one that was mainly electrogalvanized, new problems
associated with cleaning these surfaces became
apparent. Electrogalvanized surfaces were more
active than steel. The initial alkaline cleaners were
capable of forming white stains which were readily
seen through the phosphate coating and subsequent
painting. The appearance of the paint film resembled
a mapping texture and required sanding after the
prime, to correct. At times, the alkaline cleaners
formed a pinpoint white spot, slightly raised from the
surface. These areas increased in size during
phosphating and were responsible for some cratering
and protrusions through the paint film. This required
sanding prior to top-coat application. These stains
were surface analyzed using scanning electron
microscope (SEM) and energy dispersive analysis of
x-rays (EDAX) techniques and found to be comprised
of zinc oxides.
Eventually, a relatively neutral to mildly alkaline
cleaner operating in the pH range between 7.5 and
9.5 was found to provide the desired degree of
cleaning for these applications. Frequently, a small
amount of water-soluble inhibitors is used. The
inhibitors do nothing to aid in the removal of the soil,
but they are capable of eliminating the staining
problem and impart some temporary in-plant rust
protection. Neutral cleaners are now widely used,
displacing the solvent-based cleaners. They have
been proven to be safe for handling by line personnel,
they are solvent-free, they are easily waste-treated,
and they require no equipment or manufacturing
changes. Solvent reduction for these applications as a
direct result of the use of neutral-type cleaners is in
the order of thousands of gallons of pure solvent per
year per plant.
General, Neutral Cleaner Applications
This concept of using solvent-free, neutral cleaners
extends far beyond the automotive industry. Other
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uses include the steam cleaning of large parts such
as equipment, tanks, engine blocks, tools, and a
variety of painted and unpainted surfaces. It forms the
basis of cleaners for floor scrubbing (automatic and
manual) and glass, plastic, and hand wiping cleaners
for walls and fixtures. The use of solvents in cleaning
aids for these applications has been curtailed. Since
the solvent-free cleaners are neutral in pH, they are
safe to use on galvanized, steel, and aluminum
surfaces. The problem of skin irritation in personnel
who might come in contact with the concentrate or its
dilute solutions is also minimized.
The neutral cleaners do have some limitations. They
cannot be used for cleaning electrical motors.
Stubborn soils may require higher concentration levels
to be effective, resulting in a cost penalty over
solvent-based products. Organism growth is higher for
neutral cleaners which can adversely affect their
cleaning efficiency and often leads to odor problems,
particularly in aged solutions. Organism growth can be
controlled, but at an additional cost penalty and with
higher skin irritation probability.
Cleaners Before Phosphating
The degree of cleaning effected by in-process
cleaning does not reach the level required for
phosphating. Therefore, subsequent to the in-process
and oleum deck cleaning, the parts must be
processed through either one or two additional
cleaning steps. The clean surface needed for
phosphating must have a water break-free surface
after cleaning, a surface free of oxide and oil
polymerization stains, and a low surface-carbon
content. The surface carbon is a measure of organic
carbonaceous soils such as lubricants, rolling oils, and
inorganic carbon. It does not measure alloyed carbon.
The measurement of the surface carbon is a
laboratory procedure based on coulometric
measurements involving pyrolytic oxidation
techniques. The surface carbon content must be
below 0.4 mg/ft2 if a high quality phosphate coating is
to be achieved. Higher values of surface carbon can
lead to phosphate coatings that possess marginal
adhesion and corrosion protection.
Excellent cleaning, which meets all of the
requirements for phosphating, is achieved using hot
cleaners operating at about. 150 to 160°F. The
cleaning method could be spray, spray-dip, or
immersion. In recent years, a considerable need
developed for low-temperature cleaners because of
the high cost of energy.
Initially, low temperature cleaning was made possible
by solvent additions to conventional cleaners. The
results achieved were satisfactory. Solvents such as
kerosene, mineral spirits, or butyl cellosolve were
found suitable. Cleaning temperatures were reduced
from 150°F to 100 to 110°F with no sacrifice in
quality. However, solvent usage necessitated better
control of the rinse stages to prevent solvent carry-
over. Knock-off risers at the exit of the cleaning and
rinse stages helped to control solvent carry-over.
These emulsion-type cleaners are in use today, but in
view of the EPA and OSHA interests in minimizing
solvent emissions their use is destined to be short
lived.
The average solvent content in these cleaners varies
between 5 and 10 percent by weight of the
concentrate. For a 10,000 gal. cleaner tank operating
at a nominal 3 oz/gal., the solvent content is at least
187 Ibs. Cleaners are dumped frequently and
recharged every two to three weeks. Over a period of
one year, this amounts to over 3,000 Ibs. of solvent
per cleaning tank that must be waste-treated. This
quantity is actually understated, because the
calculations do not include the normal replenishment
of cleaner which takes place to maintain cleaner
efficiency.
In the automotive industry, the newer generation
phosphating machines are being constructed with
tanks in the 90,000 to 100,000 gal. range. The use of
solvent or emulsion cleaning in these large tanks
would further magnify the problem.
Most, if not all, of these solvent-containing cleaners in
the automotive industry have been replaced or will be
replaced by low temperature, solvent-free cleaners.
This direction is taking place primarily due to the
strong influence of local and state regulations
governing solvent emissions and very conscientious
monitoring by the officials.
The development of efficient low-temperature cleaners
was performed in concert with the steel companies,
lubricant suppliers, and the R&D staff of the
automotive companies. Lubricants and rolling oils
were modified or changed completely to make them
more receptive to cleaning. Steel mills modified their
practice and control in making the metal coils to
reduce surface carbon contamination, and the
chemical suppliers modified the cleaning composition.
The R&D staff monitored and evaluated the activities
of the suppliers and modified cleaning equipment
where necessary.
In general, the low-temperature cleaners are more
alkaline and equally aggressive when compared with
hot cleaners. They differ in the type and variety of
surfactants and emulsifiers to provide low to no
foaming characteristics. Soil retention in the cleaner
bath was found to be better; soil redeposition
characteristics were improved primarily because of the
lower cleaning temperatures and the variety of
surfactants employed.
Short high-pressure (1,000 psig) cleaning zones were
installed, in some instances, between the oleum deck
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and the first cleaner stage. The high pressure was
capable of physically removing very tenacious soils
such as carbon and loose sealants not removed
earlier.
Thermal oil separators have been installed in
conjunction with the first cleaning stage. This works
on the principle of heat. Periodically the oil-laden
cleaner bath is transferred to a large tank equipped
with a heater. As the cleaner bath is heated, the oil
separates and floats to the top where it is collected in
a suitable vessel. The oil-free cleaner bath is then
piped back to the cleaner stage. This technique
increases the bath life of the cleaner and decreases
the frequency of dumping. This procedure is not
successful for solvent-based cleaners because the
solvent would be effectively removed with the oils and
cause the cleaning efficiency to fall off.
Ultrafiltration has also been attempted to accomplish
the same purpose as thermal oil separators, but it has
not been readily accepted by industry due to its
comparatively high cost and maintenance
requirements.
Low-temperature, solvent-free cleaners of this type
and some of the techniques and equipment
modifications are presently in use in many spray and
immersion cleaning tanks in the automotive, coil, and
fabricated metal industries.
Such cleaner formulations are characterized as being
heavy duty and find application where very difficult
cleaning problems exist. They can be formulated for
soak or spray use. As a maintenance cleaner they are
capable of removing heavy greases, burnt-on soil,
pigmented buffing compounds, and even light rust on
steel and galvanized surfaces. Because they are so
aggressive in cleaning action, they are very effective
in cleaning recessed and hidden areas, the only
criterion being that the solution is able to reach that
area. Typical applications are soak cleaning of all
types of fasteners, pumps, engine components, and
similar uses where emulsion cleaning is commonly
used. Frequently ultrasonic equipment is also used.
Care must be exercised in using these cleaners since
they operate at relatively high pH levels. Skin contact
can lead to burns or irritation and personnel must be
cautioned accordingly. Aluminum surfaces and
galvanized surfaces can be etched and painted
surfaces can be softened and even stripped. In such
cases, it may not be possible to replace solvents. The
use of such aggressive cleaners should be
determined on a case-by-case basis.
Add Cleaning
Parts which have been stored for any period of time
may become slightly oxidized despite being treated
with a protective oil film. This condition is visible on
steel parts as a light yellow coloration or in more
severe cases, red rust. Galvanized surfaces may
show evidence of white rusting. Aluminum oxidation
appears as white to black pitting. Protective oils can
sometimes oxidize and in the process react with the
metal surface to produce a hard, impervious, varnish-
type film. These films, frequently called polymerized
oil spots, resist alkaline cleaning and generally lend
themselves to acid cleaning. Some of the metal must
be dissolved to reach under the polymeric film which
is then lifted from the surface. If these oxidation
products are not removed completely, poor
phosphating and paint quality will result. If not
removed, these oxidized areas will either prevent
phosphating completely or will allow an improperly
formed or marginal coating to be formed. Adhesion of
phosphate coating and, therefore, the paint film also
will be inferior. These sites will be prime areas for
paint chipping and corrosion.
Acid cleaning is the most effective method to remove
this surface condition. While serious, these conditions
are generally localized and should be addressed on a
case-by-case basis. An operator using a brush or a
sponge soaked with the cleaner manually wipes the
area until the contamination has been removed. A
light wiping with a water-soaked sponge removes the
excess cleaner and stops the cleaning action.
Phosphoric- or citric-acid based cleaners have found
use in this application. In addition, surfactants and
emulsifiers along with solvents such as alcohol or
butyl cellosolve are incorporated into the mixture to
aid in soil removal and acid penetration. The use of
acid cleaning does not approach that of alkaline
cleaning. Acid cleaners are usually purchased in
several drum lots and placed in the various areas
where inspection and repair work is performed.
However, this type of cleaner is found in all
automotive plants and job shops and is even sold over
the counter in automotive retail shops and paint
stores. Thus, it is a source of solvent emission.
Solvent content varies but averages about 10 percent
by weight of the concentrate. A single 650 Ib net drum
would contain 65 Ibs of solvent. Most of these
products are found being used in areas having only
general ventilation, which is very questionable and
could be harmful.
The citric acid-based formulations are superior to the
phosphoric acid products because they do not
passivate the cleaned area. Any residue remaining on
the surface after cleaning is easily removed in the
alkaline cleaner stage. Phosphoric acid products can
react with the metal to form a thin phosphate
conversion coating that will interfere with subsequent
steps. On the other hand, if subsequent phosphating
will not be performed, this thin film does provide a
base for paint bonding, but not one of high quality.
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These products have been reformulated without
solvent. In place of the solvent a mixture of high HLB
(hydrophilic, lipophilic balance) and low HLB
surfactants are used. Surfactants having HLB values
around 3 readily solubilize the oily deposits on the
surface and allow quick and effective action of the
acid on the oxidation sites. High HLB surfactants
(values of 10 or greater) allow rapid soil emulsification
and make it easier to rinse off the reaction products of
the cleaning action and excess unused acid.
Acid cleaning of this nature, while being of a
magnitude of use lower than alkaline cleaning, does
have a place in industry.
Vapor Degreasing
Vapor degreasing units basically are devices for
heating a volatile solvent. By providing a simple
cooling jacket above the liquid solvent, the zone
between the liquid and the cooling jacket becomes
enriched with solvent vapor. The freeboard area
above the water cooling jacket is equipped with
condensing coils to help control any solvent emission
into the workplace. Cleaning takes place by the hot
vapors condensing on the part. This vapor
condensation continues until the part reaches the
temperature of the vapor. The commonly used
solvents are 1,1,1 trichloroethane, trichloroethylene,
perchloroethylene, and methylene chloride. Vapor
degreasing is used for cleaning many surfaces
including glass, plastics, and combinations of metals
and plastics provided the solvent does not react with
any of these surfaces.
Vapor degreasing is a very effective cleaning method
but it is not capable of producing a chemically clean
surface. In addition, it has a number of limitations. It is
not an effective method for removing heavily
pigmented soils, often leaving residues of the pigment
which resist subsequent removal. Thin sections of
metal heat almost instantly to the vapor temperature
of the solvent and little to no soil is removed. To
produce a truly clean surface to the degree required
for phosphating or plating, a subsequent alkaline or
acid cleaning step is required.
Several modifications to existing vapor degreasing
units can be made to reduce solvent air emissions.
Increasing the freeboard area above the water cooling
jacket and reducing the time of transfer of the parts in
and out of the unit will improve the situation.
Mechanizing the lowering and raising of the cover of
the tank to minimize open cover time and using fully
loaded racks are very important. Where the parts to
be cleaned are of a uniform size, equipment designed
with openings preferably fitted with cold dry air knives
can be very effective. Maintaining the equipment in
good operating condition and keeping the
water/separator functioning properly will prolong the
life of the vapor degreasing system.
Another alternative is to replace the vapor degreasing
unit with an alkaline or acidic, aqueous-based cleaner.
Alkaline cleaning is finding favor and in certain areas
has been proven to be more effective than vapor
degreasing. Typical examples where this has occurred
are in the manufacture of aluminum computer discs
and production items such as television tube grids or
radio panels which contain a screen-like series of
minute holes across the surface.
The computer discs are highly polished and mirror-like
in appearance. It is important to retain this appearance
throughout the manufacturing sequence. This is a
highly technical application where cleanliness reigns
supreme. Immersion alkaline cleaners based on
builders such as complex phosphates, biodegradable
free rinsing, and water soluble surfactants together
with specially formulated silicates to prevent any
possible metal attack, are being used for this purpose.
Such cleaners are very safe to use from a personnel
viewpoint and require minimal control to continue
effective.
Cleaning of television shadow masks or other similar
shapes which contain a series of tiny holes was
always considered ideal for vapor degreasing. It was
considered to be the only way cleaning could be
accomplished inside the holes. However, it was
determined that spray alkaline cleaning was a superior
method for this application. Highly sequestered
cleaners free from silicates or soda ash, which have a
tendency to precipitate hard water salts, and very low
surface tension producing surfactants are required.
After cleaning, the part is rinsed with a final de-ionized
water rinse and dried in a low heat convection oven.
This approach leaves the surface chemically clean,
free of cleaner residue, and free of thin oily films
commonly found after vapor degreasing. Surfaces
thus produced are suitable for phosphating, plating, or
otfier applications.
Paint Strippers
In every job shop or manufacturing site where parts
are cleaned and painted, there is a need for paint
strippers. Methylene chloride is the most widely-used
solvent for removing paint from steel and aluminum
surfaces. There is a nationwide research goal to find a
viable substitute for methylene chloride as a paint
stripping agent, but to date, none has been found
despite many claims being made to that end.
Methylene chloride by itself is not too effective as a
paint stripper. It needs the help of various acidic
activators, such as formic or acetic acid, to be truly
effective. Formic acid is far and away the most
effective activator available. Inhibitors are added to the
mixture to protect the metal surfaces against acid
attack during the stripping process and to prevent the
stripped bare surface from flash rusting while the parts
are drying.
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Stripping tanks vary in size from several gallons to
several hundred gallons. The methylene chloride
content averages 90 to 95 percent. Because of its low
boiling point of 105°F, the tanks generally are fitted
with lids that can be mechanically raised or lowered
during use to prevent evaporative losses. This
technique to reduce evaporative losses is helpful but
not truly effective. At times water seals are employed,
but these are seriously lacking in their capability to
prevent evaporative losses, and, in addition, their use
serves to decrease the life expectancy of the stripper
bath. The organic acid activators preferentially migrate
from the solvent layer to the water layer, where they
are more soluble. As the migration progresses, the
stripping efficiency falls off until it is no longer
effective for the purpose intended.
Seals are available commercially that have proven to
be very effective. These seals consist of highly polar
components which are insoluble in methylene
chloride, but are soluble in water. These seals, being
lighter than methylene chloride, float on the surface.
As the stripped part is being removed from the tank, it
passes through the seal layer where the seal layer
displaces the methylene chloride solvent, leaving a
thin film of a water soluble component. By
incorporating a rust inhibitor in the seal layer, flash
rusting during drying is eliminated. Evaporation
savings using these seal layers can be as high as 40
percent. There is little to no tendency for the
activators to migrate into the layer because they are
more soluble in the methylene chloride. As a result,
paint stripping efficiency remains constant for the life
of the bath.
Products have recently become available where the
methylene chloride content has been reduced by 60
percent. Techniques have been found to produce a
stable solution of methylene chloride in an aqueous
medium. In effect, the methylene chloride molecule
becomes surrounded by water molecules resulting in
an in situ water seal. This approach is certainly novel
and it is tremendously effective in reducing
evaporative losses. The activity of the acid activators
and inhibitors commonly employed has been found to
be enhanced in such a medium. This technique
effectively minimizes evaporation losses and because
of the lower usage of methylene chloride, it is a viable
method for source reduction of a powerful paint
stripping solvent.
Many of the techniques to minimize solvent emissions
for vapor degreasers can be applied to cold paint
strippers. The other approach to eliminate solvents in
paint stripping is to consider the use of alkaline
materials based on caustic soda. As a rule, these are
solvent free but to be effective they must be used at
temperatures near boiling.
Alkaline strippers are very useful for stripping all types
of paint. Several disadvantages exist with their use,
however. Extreme care must be exercised by the
operating personnel to prevent burns resulting from
skin contact with hot stripping solutions. The risk of
skin irritation is always present if the ventilation is
faulty and caustic mist escapes into the air. The
alkaline strippers cannot be used to strip paint from
aluminum or galvanized substrates since these metals
are readily dissolved by hot alkaline solutions. Thus,
while alkaline strippers are widely used, they are
restricted to removal of paints from steel surfaces.
Booth Coating Compounds
Booth coating compounds are removable temporary
barrier coatings which are applied to spray booth
walls, gratings, and floors to facilitate entrapment and
disposal of accumulated overspray paint. In addition,
they serve to provide an excellent light-reflecting
surface which is very beneficial in application of paint
and results in a reduced number of rejects. The white,
dry, flexible, barrier coatings are considered the best
type to use because they afford the best light
reflection. As the paint overspray accumulates, the
barrier coating is simply peeled from the surface,
discarded, and a new barrier coating is applied either
by brushing or by means of a paint spray gun. The
entire sequence of peeling the coating from the walls
of the paint booth and the application of a new film
takes about one hour, depending on the size of the
booth. Half of that time is used to allow the coating to
dry before use.
A typical white, booth-coating compound consists of
an acrylic copolymer resin dissolved in a mixture of
methylene chloride, xylene, and toluene and
pigmented with titanium dioxide to form a stable
emulsion. Small amounts of plasticizer are used to
keep the dry film flexible and pliable. Approximately 50
percent by weight of these compositions consists of
solvent which escapes during drying. One gal. usually
is capable of covering about 500 ft2 of area at 1 to 3
mils thickness. Each gallon contains about 6 to 7 Ibs
of solvent. Very good local ventilation is required
during the application process, and spray equipment
which contains any aluminum or galvanized steel parts
must be avoided because of the danger of hydrogen
gas forming. Stainless steel spray equipment is an
absolute requirement. There have been instances
reported of asphyxiation resulting because of
inadequate or inoperative ventilation. Fortunately, this
was a temporary condition and the personnel
recovered completely after being removed to fresh air.
Recently, high solid formulations have been
developed and sold commercially. About 85 percent
by weight represents the total solids content of
waterborne co-polymer emulsion and titanium dioxide
pigment. The remainder is water and a small amount
of a cellosolve-type solvent. Average VOC content of
commercially available booth coating compounds of
this type is 0.2 to 0.3 Ib per gal.
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These products perform as well as the solvent-based
products, and they possess several advantages over
the solvent-based materials:
They are non-flammable;
They provide 10 to 20 percent greater coverage;
and
There is no restriction as to construction of spray
guns.
The high solids, water-based booth coating
compounds are rapidly replacing the solvent-based
products and they are considerably safer to apply.
These products are used wherever parts are painted.
Summary
This brief review highlights the use of solvents for
parts cleaning and illustrates some of the measures
being taken by industry to reduce or eliminate
solvents. Not all of the alternatives discussed are
effective or desirable as a replacement for solvents in
every case. However, viable alternatives for solvents
are continuing to be sought through R&D.
In areas where solvent usage is necessary, redesign
of equipment, modification of operating procedures,
and improvements in solvent reclamation techniques
have been examined successfully and implemented as
a solvent source reduction method.
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Chapter 7
Solvent Waste Minimization by the Coatings Industry
Neil H. Frick
Gerald W. Grafter
PPG Industries, Inc.
Alison Park, PA 15101
The issue of waste disposal is of national concern.
Solvent waste reduction is especially relevant in the
coatings industry, because the $30 billion worldwide
coatings market has traditionally relied upon solvents
in large quantities to manufacture, apply, and clean up
coatings. The intent of this paper is to develop the
reasons for solvent use in coatings through looking at
the product requirements, and then to inform you of
the actions being taken by coatings manufacturers,
application equipment manufacturers, and end users
to reduce solvent usage.
Functions of Coatings
Coatings can be broadly defined as decorative and/or
functional materials which are applied to the surface
of an object. Inks, adhesives, and sealants can be
viewed similarly. Some common examples of coated
objects include:
Bridges
Autos
Buildings
Photographic film
Wall coverings
Mirrors
Furniture
» Aircraft
Storage tanks
Appliances
These examples will help us to illustrate some
coatings product requirements. A significant fraction of
the list employs metal substrates:
Bridges
Autos
Buildings
Mirrors
Aircraft
Storage tanks
All of these products are subject to corrosion, and it is
through the use of coatings that we are able to build
long-lasting products from metal. Conse-quently,
corrosion protection represents one of the most
important functional purposes of coatings.
Some other common functional properties of coatings
are:
Aesthetics
Durability
Chemical resistance
Flexibility
Adhesion
One property on the list is aesthetics. Each of these
product groups has color, gloss, and appearance
requirements. It is no longer true that you can have
your Model T in any color you want, so long as it is
black. The mirror finish of your automobile and the
non-reflective finish of a metal building are made
possible through coatings. In addition, we expect the
appearance of these products to remain unchanged
after years of exposure to sunshine, smog, and rain.
Let's call this durability. Range tops are exposed to
extremes in temperature as well as to a variety of
aggressive materials ranging from abrasive cleaners to
hot grease to spaghetti sauce stains. This is thermal
and chemical resistance.
Aluminum siding is a good example to illustrate
flexibility. It is manufactured by painting wide strips of
metal, cutting the strips to the appropriate width, and
forming the final shape. The coating must survive the
47
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cutting and forming, and then retain color and gloss
on your home for many years.
House paint is an excellent example of a product
which must be field applied on a wide range of
surfaces - bare wood, brick, vinyl, metal, new, old,
previously painted, wet, dry, hot, cold. We expect it to
adhere and provide years of protection and beauty.
Plastics represent an additional set of opportunities:
adhesion, impact resistance, surface defect coverage,
barrier properties, weatherability enhancement, and
others.
So far, we've talked only about the functional
properties of coatings. Many additional considerations
go into the design of a coating:
Functionality
Product safety
Dry/cure speed
Environmental safety
* Aesthetics
Economics
Product safety requires a product which can be
manufactured, transported, used, and disposed of
safely. This necessitates extensive testing of raw
materials and finished products for health and
environmental effects, flammability, reactivity, and
corrosivity. Unacceptable materials are deleted from
candidacy.
The mention of paint creates an image of a paint roller
and house paint, hard work, several hours' drying
time, and as much as several days to achieve full
properties. I would like especially to call your attention
to drying time. Model Ts required several days for
painting. This was a consequence of several coats of
solvent paint and drying times of hours for each coat.
Imagine today's automotive assembly lines producing
greater than 60 cars, per hour, but being bottlenecked
for days while the finish dries and is recoated.
Production speed requirements thus have become
another requirement for coatings design.
We spoke briefly of aesthetics from the point of view
of requirements, but how does one achieve a smooth,
sag- and pop-free finished product?
The answer is that it is a design criterion, just like
color or corrosion protection. Products are applied by
a wide range of methods, including spray, dip, roll,
curtain, and electrodeposition. Traditionally, large
quantities of solvents have played a major role in
achieving acceptable appearance, and only in recent
times have alternatives begun to be available.
Coating Formulation
Early coatings were essentially all solvent-reduced
products derived from natural products such as
lacquer, coal tar, and oils. These products were
severely limited by today's standards in their ability to
deliver corrosion protection, durability, and quick
drying.
Deficiencies such as these, together with the
availability of a wide variety of synthetic organic
building blocks, have led to the development of a wide
variety of synthetic polymers. Some examples include:
Epoxies
Acrylics
Fluorocarbons
Polyesters
Urethanes
Polyamides
These materials provide substantial improvements in
corrosion protection, adhesion, durability, flexibility,
drying rate, and other properties. " But this first
generation of synthetic polymers did little to reduce
the organic solvent requirement.
Reduction and elimination of solvents in coatings has
been a priority for many years at PPG. One obvious
reason is environmental legislation which limits the
allowable solvent emission by industry. EPA guidelines
for VOCs in coatings are shown in Table 7-1.
Solvent Reduction
The EPA limits the amount of solvent allowed per
gallon of paint used in various industries. These
guidelines are of very limited use today, because state
and local rules, on a case-by-case basis, provide for
more or less solvent usage. Perhaps more
importantly, the industry has been able to do better
than these guidelines in at least some cases.
Container sprayliners, basecoats, and varnishes
surpass the guidelines. Coil coating lends itself to
incineration, and this is widely practiced. So clearly
there are other motivations for reducing solvent
usage. Some reasons for the reduction of solvent
usage are:
Environmental
Product safety
Economics
Productivity
In addition to environmental safety, solvent reduction
or elimination can improve product safety through
reduced chemical exposure and flammability. Solvents
normally do not become part of the finished product,
and as such become an expense both in use and
disposal, which does not add to the ultimate product
value. Henry Ford used several coats of lacquer
48
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Table 7-1.
EPA Guidelines-for Maximum Volatile
Organic Content of Coatings*
Process
Limitation
(Ib/gal)
Can coating
Sheet basecoat& overvarnish; two- (2.0) 2.8
piece can exterior
Two-, three-piece can interior body (3.6) 4.2
spray, two-piece can exterior end
Side-seam spray 5.5
End sealing compound 3.7
Coil coating (0) 2.6
Fabric coating 2.9
Vinyl 3.8
Paper 2.9
Auto and light-duty truck
Prime 1,9
Topcoat 2.8
Repair 4.8
Metal furniture 3.0
Magnet wire 1.7
Large appliance , 2.8
Miscellaneous metal parts 0.4-4.4
Wood paneling
Printed interior ' 1.7
Natural finish hardwood . 3.2
Class II hardboard 2.7
* Source: R.W. Tess and G.W. Poehlein, Applied Polymer
Science, Second Edition, ACS Symposium Series 285, p.
689.
because the solids were so low that several coats
were required to provide the required properties, and
consequently days were invested in painting each car.
Improved solids and solventless coatings can provide
more film build per coat, and thus also improve
productivity by requiring fewer coats.
Recent Advances
Some recent advances in coatings technology are:
High solids coatings
Water reducible coatings
Powder coatings
100 percent reactive coatings
Electrodeposition
Application efficiency improvements
High solids describes coatings with improved volume
solids. While natural lacquers and early synthetics
could be applied at 20 to 40 percent volume solids,
high solids products rely not upon drying alone, but
also upon polymerizing (curing) as they dry. This
allows the use of lower molecular weight materials
with reduced solution viscosities; therefore, volume
solids of 60 to 80 percent can be achieved. Where
high solids coatings have replaced conventional solids
materials, solvent reductions on the order of 50
percent have been achieved. As we shall see later,
equipment innovations multiply this improvement.
Powder coatings are solventless. These powders melt
and fuse into *a continuous coating when heated.
Obviously, they represent a 100 percent reduction in
solvent usage. They are particularly useful in thick
films where excellent chemical resistance is required.
Dishwasher rack coatings represent an excellent
application of powder coatings. On the other hand,
uses which require excellent smoothness, thin films,
or low cure temperature are only now becoming
possible with powder coatings.
A technology that does an excellent job of handling
thermally sensitive substrates such as plastics, paper,
and wood, is radiation-curable coatings. With this
technology, solvent is replaced by reactive molecules
which polymerize in place upon activation by
ultraviolet light or electrons. The weaknesses in this
technology include adhesion-sensitive substrates and
complex-shaped particles, although this latter problem
is now being addressed with a 3D-UV curing process.
A traditional problem with waterborne polymers is
water sensitivity. Progress has been made, however.
Crosslinkable waterborne polymers, reactive
solubilizing groups, and improved surfactants
represent advances which have allowed the use of
waterborne polymers in some industries. Humidity
variations and flow limitations currently prevent
broader application of these products, especially in
spray applications. Where waterborne products can be
used, solvent reductions ranging up to 100 percent
can be realized.
A specialized variety of waterborne coatings are
electrodepositable. These coatings are applied by
immersing the article to be painted in a coating bath
and electrically depositing the paint film on the article.
The process is exceptionally effective at coating
obscured areas of complex articles. The coatings can
be designed to provide outstanding corrosion
protection,'and indeed, cathodic electrodeposition is
largely responsible for the improved corrosion
resistance of today's automobiles. Electrodeposition is
limited to electrically conductive substrates. It also
serves to introduce another concept: transfer
efficiency.
In the past few years, great strides in spray
application efficiencies have been made by close
cooperation of the coatings user, equipment
manufacturer, and coatings supplier. In the past,
spray efficiencies in the range of 20 to 30 percent on
49
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automotive lines (meaning that only 20 to 30 percent
of each gallon of paint would come to rest on the part)
were not unusual. Today, application efficiencies in
the range of 60 to 80 percent with coating solids near
60 percent are not unusual.
The consequences of improved solids and transfer
efficiency as compared to low solids, nonelectrostatic
application, in terms of the amount of coating used to
apply one kilogram of dry product, are illustrated in
Table 7-2.
Table 7-2.
Consequences of Improved Solids and Transfer
Efficiency
Transfer Efficiency
Kg of Reduced
Coating Necessary
for 1 kg Dry Applied
Low Solids (21%)
Low Application Efficiency (30%) 1/(.21) (.3)
High SotkJs (60%)
Hioh Application Efficiency (65%) V(.6) (.65)
16 ± kg
2.5 ± kg
results in enormous labor savings and substantially
improved labor costs.
You may think of electrodeposition as a process for
applying primers, but one-coat finishes are now
commonplace, without compromising performance.
Powders are commonly recycled. Other spray
technologies can be recycled, if attention is paid to
the composition of the recycled material as compared
with that of the fresh material.
In the future you will see more waterborne coatings,
with little or no solvent, being electrostatically sprayed
in industries where water products did not traditionally
achieve the performance criteria. Already, high solids
products have improved application latitude and
performance as compared with early high solids
offerings.
The difference between the 16 and 2.5 kg of wet
coating supplied amounts to a reduction of about 80
percent in the amount of solvent used. This
represents a cost saving for the paint user in
purchase volume, storage and inventory costs, and
disposal costs of liquid and solid waste.
Other methods of applying coatings are even more
efficient. Electrodeposition of coatings onto metal
substrates improves the efficiency in two ways. A
more uniform film results from this process (as
compared to spraying), and this reduces paint usage,
while the engineering of coating tank, rinse recovery
system, and chemistry used allows nearly 100 percent
coating application efficiency.
Roll coating (for flat substrates) also allows for nearly
100 percent'coating utilization. Advances in polymer
mechanical properties have allowed more
manufacturers to change from spraying coatings in
their facility, to the purchase of precoated stock which
is then fabricated and assembled.
Alternative coatings technologies and improved
transfer efficiency can reduce solvent usage and
minimize waste generation. What may be less obvious
is that improved product performance and application
latitude may make it possible for you to dramatically
change your operation. Improved coil coatings are
causing the home appliance industry to move from
postpainting to prepainted metal, thereby eliminating
metal cleaning, pretreatment and painting operations,
and the associated waste.
The furniture industry around the world is moving to
flatline finishing and away from postpainting. This
50
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Chapter 8
What to do with Hazardous Waste: Regulations, Management, and Disposal
Thomas F. Stanczyk
Recra Environmental, Inc.
Amherst, A/Y 74750
Throughout this country, industries as well as
governmental agencies are confronted with a number
of issues focusing on the subject of how hazardous
and contaminated solid waste should be properly
managed and controlled. These issues are receiving
increased attention as regulatory legislation governing
the management of waste magnifies in terms of
enforcement and performance standards.
As new regulatory standards are promulgated, the
volumes of hazardous waste could increase,
magnifying concerns over capacity, waste acceptance
criteria, and rising disposal costs. The services
associated with waste transportation and disposal will
continue to increase in cost through the 1990s.
These issues dictate that generators" re-assess their
existing waste management practices with the
objective of instituting policies, procedures, and
operating modifications which collectively ensure
optimum chemical control and waste minimization.
This chapter focuses on source control strategies
which are effective in reducing waste volumes. Using
categorical waste types, emphasis is placed on
reduction strategies that are effective in eliminating
and/or reducing chemical concentrations causing
hazards and mobility concerns.
Introduction
In addition to the federally-mandated treatment
performance and hazard identification criteria, several
state regulatory agencies are placing restrictions and
waste limitations on commercial TSD operations. The
waste acceptance criteria associated with treatment,
incineration, and land disposal services are becoming
increasingly more stringent and restrictive, placing
additional burdens on generators as well as
commercial facilities to quantify the degree of
environmental concern by substantiating the
properties and content of each wastestream.
Generators are finding that the chemistry of a waste
needs to be well understood to ensure optimum
treatment performance as dictated by the regulatory
standards governing waste disposal. In addition, this
understanding aids in the elimination of costly options
and off-spec shipments.
In an industrial society that relies on a multitude of
complex, hazardous chemicals, environmentalists,
scientists, engineers, and lawyers find it is
increasingly important to understand the chemistry of
wastes and their potential for environmental
impairment. The creativity of many of our nation's
scientists has led to the development of literally
hundreds of thousands of "unnatural" chemicals
posing variable concerns relative to environmental
fate.
About 50,000 chemicals which have been prepared
commercially or have been identified as potentially
useful chemicals are estimated to appear on the
Environmental Protection Agency's chemical inventory
list of compounds. The exact number of chemical
substances is unknown, but Chemical Abstracts
Service's best estimate ranges from 6 to 8 million
substances. In the United States alone, there are over
5,000 chemical producers and petroleum refiners that
manufacture 50,000 to 70,000 chemicals. Approx-
imately 1,000 new chemicals are introduced into the
market every year. The complexity of this vast array
of inorganic and organic matrices raises environmental
issues with waste generation. Waste elimination,
prevention, and optimum control management each
require a scientific mentality that incorporates a multi-
disciplinary approach to understanding the factors
responsible .for waste generation.
Recent and on-going regulatory attention to the issues
and standards dictating waste minimization, land
disposal bans, and BOAT performance criteria
magnifies the importance of chemistry and its role in
the selection of technologies, process equipment,
chemical controls, and waste management practices.
Operable hazardous waste management units (i.e.,
incineration, secure landfills, and treatment facilities)
are being faced with stringent waste acceptance
criteria encompassing variable degrees of chemical
51
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content verification and hazard assessment. Design
performance specifications must account for concerns
centering around pollutant mobility as defined by the
potential for transport in air and/or water environ-
ments. Proposed hazardous waste identification cri-
teria employing the analytical procedures involved with
the Toxicity Characteristic Leaching Procedure (TCLP)
places additional emphasis on the importance of
understanding mobility concerns within variable waste
matrices.
Industry must develop a better understanding of
chemical behavior to avoid serious environmental
concerns resulting from the management of
contaminated waste residues as well as chemical
residues which could occur from future process
formulations. This should take into account process
mechanisms involving chemical transport, trans-
formation, and accumulation mechanisms before
wastes are generated and treated. Material balances
need to describe where and at what concentrations
chemical contaminants are accumulating and affecting
reduction strategies applicable to recycling or source
implementation. The combined factors can be readily
identified using an audit approach that emphasizes
chemical and physical waste properties and their
impact on waste generation and strategic planning.
During the last decade, this country has seen the
institution of several health, safety, and environmental
laws protecting human health and the environment
from an increasing number of known, quantifiable
toxic substances. This legislation includes:
The Toxic Substances Control Act (TSCA)
The Resource Conservation and Recovery Act
(:RCRA)
The Occupational Safety and Health Act (OSHA)
The Hazardous and Solid Waste Amendments
(HSWA)
The Federal Water Pollution Control Act (FWPCA)
The Clean Air Act (CAA)
The Safe Drinking Water Act (SDWA)
The Food, Drug, and Cosmetic Act (FDCA)
The Federal Insecticides, Fungicides, and
Rodenticides Act (FIFRA)
In each law, a commonality exists which addresses
chemical substances, potential routes of mobility, and
hazard assessments measuring health and potential
environmental risks. On-going advances in design
performance standards have resulted in variable
degrees of analytical sophistication allowing for
detection and confirmation of complex pollutants
within various waste matrices. Regulatory per-
formance standards mitigating toxicological impacts
have dictated sensitive analyses covering an array of
inorganic and organic pollutants typically characterized
as priority pollutants.
Priority Pollutants
Waste reduction audits quantifying feedstock usage
and material flow must take into account individual
constituents and their potential for being found in
wastes as priority pollutants. Typical classifications
warranting review are summarized below.
Cyanides
Compounds classified as cyanide compounds,
thiocyanates, and isocyanates are all different in terms
of mobility and hazard potential. Isocyanates are
hydrolyzed in air to the corresponding carbamic acid
intermediate. Under normal conditions, thiocyanates
do not dissociate to free cyanide; however, under
elevated temperatures and/or conditions with acids,
decomposition occurs yielding emissions of highly
toxic cyanide fumes. Cyanide and ferricyanide are
soluble in water with mobility being accelerated in the
presence of alkaline conditions.
Photographic Processing Waste
Wastes classified under this heading generally include
hydroquinone,, methyl ethyl ketone, formaldehyde,
acetic acid, acetone, silver nitrate, silver iodide, silver
bromide, and potassium carbonate. The organic
constituents range from high volatility (ethanol and
acetone) to low volatility (2,4-dinitrophenol). Waste
types generally contain water soluble constituents
(i.e., chloroform, ether, acetone, benzene, and
alcohol). Other constituents are preferentially miscible
with soluble oils (acetic acid, acetone, and methyl
ethyl ketone). Organic and inorganic constituents
associated with processing wastes are classified as
mildly to highly toxic.
Phthalate Esters
Phthalate esters used predominantly in relation to
plastics manufacturing are generally insoluble in water
and pose minimal concern in terms of volatility.
Compounds typically found in this group include
diethylphthalate, benzyl butyl phthalate, di-n-octyl
phthalate, di-n-butyl phthalate, and bis-(2-ethyl hexyl)
phthalate. The stated compounds are generally
classified as irritants, with low toxicities and poor
affinity to photolytic decomposition or hydrolysis.
Volatile Organics
The non-halogenated volatile organics are soluble in
water to varying degrees. Aromaticity will affect
mobility and adsorption mechanisms. The halogenated
organics are slightly soluble in water but they
generally are all very volatile.
52
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Aliphatic Hydrocarbons
Typical compounds (isopentone, neopentahe, and
isobutone) vary in terms of properties influencing
pollutant mobility and stability. Most aliphatics are only
slightly water soluble. Compounds of high water
solubility are adsorbed to a lesser extent than the less
soluble compounds. Hydrocarbon degradation is likely
to be greater in the oxidized surface layer.
Petroleum Products
Oils categorized as petroleum-based generally contain
straight chain and cyclic aliphatic hydrocarbons. Oils
typically used in industry can contain low boiling
aromatic hydrocarbons (benzene, toluene, ethyl
benzene, xylenes) and higher boiling polycyclic
aromatic hydrocarbons (naphthalene, anthracene,
phenanthrene). Sulfurized fats, polyisobutylene, and
proprietary agents may be used in lubricating oils.
Refined mineral oil, ethylene-propylene, and
chlorinated paraffin may be present in cutting oils,
while sodium sulfonate, sodium rosinate, and sodium
naphenate are used in soluble oils. Many of these
constituents can pose mobility problems if allowed to
interact with other highly toxic and volatile
constituents.
Correlating the presence/absence of these
constituents with feedstock usage and process by-
product generation becomes even more important
when it is necessary to account for Appendix IX,
Hazardous Substance List (CERCLA), Appendix III
(California List), and several state-mandated land
disposal bans accounting for total organic content. A
cross-reference of some of the regulations governing
chemical constituents normally detected in variable
waste matrices is given in Table 8-1.
Wastestreams shipped off-site for treatment and
disposal are being evaluated for the presence of
constituents which would restrict acceptance.
Some of the criteria requiring review are:
Physical State:
Free liquid test determinations are dictating the
need for volume reduction (liquid-solid), phase
separation, and chemical stabilization effective in
pollutant immobilization.
Solubility:
Iri addition to EP Toxicity and TCLP, several
states have placed solubility limitations on
common contaminants including metals, metal
salts, inorganic non-metallics, reactives, and
oxidizers. Values exceeding accepted concen-
trations require pollutant removal and/or
immobilization.
Table 8-1. Regulatory Standards Addressing Usage
and Control of Commonly Used Solvents
Applicable Regulatory Listing
TCLP
(Part
Chemical 351
Constituents PP SARA HSL App. Ill App. IX Prop.)
Acetone
N-Butyl
alcohol
Chloroben- *
zene
Methyl ethyl
ketone
Methyl
isobutyl
ketone
Methylene
Chloride
Perchloro-
ethylene
Toluene
1,1,1-
Trichloro- ^
ethane
o,m,p-
Xylenes
App Appendix
PP Priority Pollutant
HSL Hazardous Substance List
Flash Point/Vapor Pressure:
In addition to restrictions on total organic content,
several states have restrictions on flash point and
volatility, forcing generators to treat wastes in a
manner that will suppress flash point or remove
constituents of concern.
Total Volatile Organic Content:
Federal and state land disposal acceptance
criteria have limited the total content of volatile
organics which can be present in a waste being
considered for land disposal.
Total Organic Content:
Restrictions are in place which dictate total
allowable quantities of organic constituents that
can be present in a waste categorized as toxic.
There are several other limitations and restrictions
addressing mode of handling, special cover, reactivity,
compatibility, and leachability.
In terms of leachability, the proposed TCLP procedure
could significantly increase waste volumes impacting
large volumes of solid waste that may, by the nature
of the generator's current mode of handling, contain
hazardous substances deemed mobile under the
proposed tests. Some of the mobility characteristics of
53
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organic constituents identified by the TCLP organic
fraction are shown in Table 8-2.
Table 8-2. Mobility Characteristics of Organic Compounds
Volatility at
Ambient
Boiling Point Solubility in Water at Temp, (mm
°C Ambient Temp. Hg)
Chtorobenzone
Cresds
1,2-Dtchloro-
bonzcno
Ethylacclata
Methyl clhyl ketone
Methyl isobutyl
kolone
Toluene
1,1.1-Trichloro-
elhano
Trichloroethylene
Xylene
Melhytene chlondo
132
192
180
77
80
116
111
75
87
137-144
40
472 ppm
24,000-31,000 ppm
145 ppm
100 ppm
353,000 ppm
200.000 ppm
535 ppm
4,400 ppm
1,000 ppm
183 ppm
16,700 ppm
9.0 (Extrap.)
0.012 (25°)
1.5 (25°)
73.0 (20°)
77.5 (20°)
15.7 (20°)
28.7 (25°)
96.0 (20°)
6.0 (25°)
362.0 (20°)
A review of the proposed extract limitations,
referenced in Table 8-3, raises concerns that many of
the wastes commonly containing these constituents
will fail the test, thus resulting in their re-definition as a
hazardous waste.
In retrospect, a waste reduction strategy can utilize a
cause-effect approach incorporating existing waste
management practices and wastestream charac-
teristics. By defining pollutants of concern, individual
waste types can be prioritized on the basis of volume,
pollutant loadings, and environmental impact, taking
into account restrictions on current disposal practices.
This approach will generally result in a re-assessment
of existing waste management practices with
emphasis being placed on source reduction/treatment
alternatives effective in removing pollutants. It is
applicable as well to wastewaters, oils, solvents, air
emissions, and other waste types not typically
managed by land disposal. Waste generation profiles
will allow for objective assessments of source
reduction, recycling, and treatment. Some of the basic
questions which need to be addressed with each
waste evaluation are:
Is the waste amenable to treatment and land
disposal in its existing form? If not, can the waste
be modified in a manner acceptable to the
process as well as the final mode of disposal?
Will the treatment process create a waste by-
product more hazardous and/or toxic than the
waste originally generated?
Can the waste and/or constituent(s) be
segregated in a manner that would eliminate
and/or reduce hazard potential and/or toxicity?
Can the chemical and/or process resulting in the
hazardous by-product be replaced or modified in a
manner eliminating the problem?
Chemical Feedstock Procurement and
Usage
One of the source control strategies warranting review
and implementation deals with the generator's policies
and procedures for chemical feedstock procurement,
storage, distribution, and usage. Some of industry's
problems with excess waste generation occur from:
excess volumes of inventory, off-spec reagents, poor
controls over purchasing and distribution, no
accountability of ancillary process chemical usage,
and a basic lack of hazard awareness.
One of the objectives of a source control strategy is to
establish a tracking system that, in addition to
accounting for inventory, distribution, and usage, will
allow the generator to correlate the presence of
hazardous substances with feedstock. The lack of
hazard awareness is generally one of the major
contributors to waste generation. In most cases, the
problems are not process by-products but ancillary
chemicals (i.e., maintenance chemicals and/or
pollutant abatement reagents), which contribute to the
hazard characteristics of a spent residue (liquid or
solid) by interaction (gaseous, liquid, or solid).
Material Safety Data Sheets, chemical technical
assays, and in-house laboratory quality control
samples all generate chemical data indicative of
hazard potential. In addition to recognizing special
precautions for handling, storage, and disposal, these
data must be assessed for their impact on waste
generation. The implication of these data is often
overlooked. For example, listed in Table 8-4 are the
properties and hazard identification potential of some
common chemicals used by maintenance and/or
process generators. The presence of highly mobile
constituents that are predominately covered on all of
the stated regulatory lists can contribute to hazardous
waste generation, especially since trade-name
chemicals are rarely assessed for impact on waste
volume. By recognizing their potential impact,
generators will be able to develop strategies effective
in product substitution and/or segregation. In addition
to eliminating hazards, the generator will benefit from
a number of cost savings.
In terms of correlating waste generation with origin
and feedstock usage, it is important to assess material
balances. A typical material balance, depicted in
Figure 8-1, can be expanded to allow for an evaluation
of the criteria.
In addition to identifying chemical loadings and causes
of waste generation, this assessment will provide
strategies for eliminating the cause by feedstock
substitution or process change and/or treating the
54
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Table 8-3. Proposed Toxicity Characteristic Contaminants and Regulatory Levels
Regulatory Level Regulatory Level
HWNO Contaminants (mg/l) HWNO Contaminants (mg/l)
D018 Acrylonitrile 5.0
D004 Arsenic 5.0
D005 Barium 100.0
D019 Benzene 0.07
D020 Bis (2-chloroethyl) ether 0.05
D006 Cadmium 1.0
D021 Carbon disulfide 14.4
D022 Carbon tetrachloride 0.07
D023 Chlordane . .0.03
D024 Chlorobenzene 1.4
D025 Chloroform 0.07
D007 Chromium 5.0
D026 o-Cresol 10.0
D127 m-Cresol 10.0
D028 p-Cresol 10.0
D016 2,4-D 1.4
D029 1 ,2-Dichlorobenzene 4.3
D030 1 ,4-Dichlorobenzene 10.8
D031 1 ,2-Dichloroethane 0.40
D032 1,1-Dichloroethylene 1.0
D033 2,4-Dinitrotoluene 0.13
D0 12 Endrin 0.003
D034 Heptachlor (and its hydroxide) 0.001
D035 Hexachlorobenzene 0.13
D036 Hexachlorabutadiene 0.72
D037 Hexachloraethane 4.3
Table 8-4. Chemical Feedstock Characteristics
Hazardous Potential Regulatory
Feedstock Substance Impact
Kermak 100-W Naphtha RCRA Hazardous
(Spray Lubricant) Waste D001
Heavi-Bodied Paint Methylene CERCLA RQ 1 Ib.
Remover chloride RCRA Hazardous
Waste U080, F002
Cleaner 0954 (Brush Methyl ethyl CERCLA 5,000 Ibs.
Wash) ketone RCRA Hazardous
Waste U 159, D001,
F005
Inhibisol 1,1,1- CERCLA RQ 1 Ib.
Trichloroethane RCRA Hazardous
Waste F002, U226
Oakite 32 (Scale and Hydrochloric CWA & CERCLA RQ
Rust Remover) acid 5,000 Ibs.
RCRA Hazardous
Waste D002
M -50 Solvent 1,1,1- CERCLA RQ 1 Ib.
Trichloroethane RCRA Hazardous
Waste U226, F002
Lubrisil 1,1,1- CERCLA RQ I Ib.
Trichloroethane RCRA Hazardous
Waste U226, F002
D038 Isobutanol 36.0
D008 Lead 5.0
D013 Lindane 0.06
D0 14 Methoxychlor 1.4
D039 Methylene Chloride 8.6
D040 Methyl ethyl ketone 7.2
D041 Nitrobenzene 0.13
D042 Pentachloraphenol 3.6
D043 Phenol 14.4
D044 Pyridine 5.0
D0 10 Selenium 1.0
D011 Silver 5.0
D045 1,1,1,2-Tetrachloroethane 10.0
D046 1 , 1 ,2,2-Tetrachloroethane 1 .3
D047 Tetrachloroethylene 0.1
D048 2,3,4,6-Tetrachlorophenol 1.5
D049 Toluene 14.4
D015 Toxaphene 0.07
D050 1,1,1 -Trichloroethane 30.0
D051 1,1,2-Trichloroethane 1.2
D052 Trichloroethylene 0.07
D053 2,4,5-Trichlorophenol 5.8
D054 2,4,6-Trichlorophenol 0.30
D017 2,4,5-TP (Silvex) 0.14
D055 Vinyl Chloride 0.05
> - - .
waste in a manner that will allow for preferential
removal, potential re-use, and/or optimum
immobilization.
Assessing Data for Objective Control
Strategies
This section identifies specific concerns and
strategies for several generic waste types and/or
constituents amenable to minimization by source
control, recycling, and treatment. A summary of
applicable off-site disposal guidelines for various
categorical waste types is shown in Table 8-5. Within
the context of this paper, emphasis is placed on the
reduction strategies for metal-bearing wastewaters,
heavy metal sludges, oils, and solvent-laden residues.
The feasibility of technology usage and cost analyses
is subject to waste matrices and applicable treatment
performance standards.
Metal-Bearing Liquids
There are several mechanisms for isolating metal
waste matrix. Precipitation, co-precipitation, or co-
55
-------
Figure 8-1. Technical approach to reviewing material balances in waste reduction audits.
Input
Output:
Taskl
Chemical Loadings
Physical Properties
Chemical Content,
Volatile Organics,
Metals, Soluble Metals,
Toxic Organics and Inorganics
Physical Properties
Reactivity,
Stability,
Phase Loadings,
Free Liuqid Potential,
Solubility,
Volatility,
Flammability,
Redox Potential
Chemical Properties
Screening Protocol indicative of product quality,
Hazardous Substances,
Priority Pollutants,
Appendix III,
Specific Restricted Parameters identified by
available, current modes of disposal
Task 2
Materials Balance
Input: Synthesis,
Controls Use,
Storage,
Ancillary Chemical Usage and Storage
Output: Production Records
By-Product Releases and Locations
Variations in Releases,
Impacts of Continuous, Intermittent, Batch
Operations
Reaction By-Products
Ancillary Chemical Waste Generation
I
Task 3
Mobility Profile
Air: pathways, releases, quantities
Water: characteristics, dispersion
Soil: factors influencing loadings
Task 4
Strategic Prioritization of Pollutants of
Concern Using Cause-Effect Rating Model
Depicting Origins and Impact
Task 5
Conceptually Strategize Options for
Pollutant Substitution, Removal,
Degradation and Attenuation
crystallization are among the common approaches to
isolating metal pollutants in aquatic media. Typical
reaction mechanisms are depicted in Table 8-6.
Beryllium and antimony can be quantitatively co-
precipitated with a variety of hydroxides depending on
the pH used. Sulfides, sulfur, calcium silicate, several
phosphates, sulfates, and several carbonates are all
documented for their specific application to co-
precipitation of metals including, but not limited to,
mercury, arsenic, and selenium.
There are several mechanisms whereby organics can
be applied as metal co-precipitates providing the
proper state of the metal is well understood. As+3,
Se + 4, Cr + s, pb + 2, Fe + 2, and Fe + 3 Can be
concentrated by co-precipitation using diethyl-
dithiocarbamate. Thionalide has been used as a co-
precipitate for arsenic and antimony at ppb levels in
highly elevated salt environments. Other reagents
having documented success and potential applicability
to source reduction include co-precipitations with
quanidates, thioxinates, EDTA, alphamercapto-
benzothiazole, cupferron, and phenylfluorone.
Another strategy having application to metal isolation
and potential recycling is electrodeposition.
Other methods, each having specific application to the
isolation and concentration of metals include:
evaporation; freezing; sorption, which includes
absorption, adsorption, ion-exchange, membrane, and
combinations thereof; solvent extraction; and reverse
osmosis. Despite the many advantages of pre-
concentration techniques, physical and chemical
variables having the potential for reducing
performance efficiency must be considered. Some
56
-------
Table 8-5. Off-site Disposal Guidelines
Reclamation
Treatment
Disposal
Categorical
Waste
Types
Sol- oils
vents
Neu- Oxida- De- De- Phys- Phys- Fuel Incin-
traliza- tion wat- vola- ical ical Sup- era-
tion ering tiliza- Stabi- Blend- pie- tion
tion lization ing ment
Secure Waste
Landfills Water
Treat-
ment
Deep Treat-
Wells ment
Facil-
ities
Soluble Oils
Insoluble
Oils
Halogenat-
ed Solvents
Non-
Halogenat-
ed Solvents
Solvent-
Laden
Residue
Oily
Residue
Paint
Residue
Concen-
trated Acids
Alkali
Cleaners
Oxidizers
Aqueous
Neutral
Solutions
Aqueous
Solutions
Contaning
Soluble
Organics
Cyanide
Solutions
Reactive
Solids
Sulfide
Solutions
Contamin-
ated Floor
Sweepings
Solvent-
Laden Rags
Metallic
Sludges
Soaps/De-
tergents
Organic
Tars/
Sludges
Toxic
Organics/
Pesticides
57
-------
Table 8-6. Precipitation reactions.
Cd+2
Cr*3
Co+2
Cll + 2
Ba*2
Ba*2
Pb+2
Pb*2
Mn*2
Mn*2
Hg*2
Ni*2
Zn*2
+ 2OH'
+ 3OH-
+ 2OH'
+ 2OH"
f CO3-2
( S04-"
+ C03-3
+ 2OH'
+ C03-2
» 2OH'
+ SO4-2
+ 2OIT
+ 2OH'
-> Cd(OH)2
-> Cr(OH)3
-> Co(OH)2
-> Cu(OH)2
-» BaCO3
-* BaSO4
-^ PbCO3
-> Pb(OH)2
-* MnCO3
-» Mn(OH)2
-^ HgS04
-* Ni(OH)2
^ Zn(OH)2
i,
1,
1,
i.
i,
i,
1.
i.
i,
i,
i,
1,
1,
Ksp -
Ksp =
Ksp =
KSP =
Ksp =
Ksp =
Ksp =
Ksp =
Ksp =
Ksp =
Ksp =
Ksp =
Ksp =
2.8
7
2
2.2
1.6
1
1.5
4
8.8
1.6
6.8
2
7
X
X
X
X
X
X
X
X
X
X
X
X
X
10-14
10-31
10-16
10-20
10-9
10-1°
10-13
10-15
10-11
10-13
10-7
10-18
10-18
@ 25°C
@ 25°C
@ 25°C
@ 25°C
@ 25°C
@ 25°C
@ 25°C
@ 25°C
@ 25 °C
@ 25°C
@ 25°C
@ 25°C
@ 25°C
Ksp - Solubility product value
examples of the stated metal removal strategies are
summarized as follows:
Evaporation of wastewaters to recover metals of
specific reuse value (e.g., mercury).
Evaporation with reduction to remove metal
halides and oxyhalides of selenium and tellurium.
Activated carbon, oxidized with nitric acid, has
been used to extract divalent nickel, cadmium,
cobalt, zinc, manganese, and mercury, from
wastewaters including brine solutions.
Zeolite extraction of copper, nickel, zinc, and
cobalt.
Starch xanthate as an insoluble material was used
to extract metals without pH dependency.
Several natural materials (e.g., peat moss);
protein-containing species (wool, hair, feathers);
peanut skins; walnut meal; and various woods,
including cellulosic materials, have extracted
metals from aqueous media.
Shredded tires, including carbon black, were
documented as additives to remove mercury from
aqueous solutions.
Chelating polymer resins are employed to remove
trace metals.
Cation exchange resins have been used to
separate many transition metals such as Fe(lll),
Cu(ll), Zn(ll), Ni(ll), Ag(l), Mn(il), etc.
Chelate-type complexes have been documented
with oximes, hydroxyquinolines, nitrosophenols,
naphthols, dithiocarbamates, xanthates, and high
molecular weight amines.
Some of the summarized waste management
strategies having application to industrial wastewaters
including those containing metals as prime
contaminants are illustrated in Figure 8-2.
Heavy Metal Sludges
Chemical precipitation of wastewaters containing
soluble and/or suspended concentrations of metallics
and salts (sulfate, phosphate, fluoride) will generally
produce insoluble by-products requiring liquid-solid
phase separation. The separation technologies may
involve one of many commercially available
dewatering units including units having application to
thermal drying.
The resulting solid by-products are generally referred
to as sludge. The physical properties (e.g., solid
content, free liquid potential) and chemical content of
these sludges can vary significantly as summarized in
Table 8-7. The concentrations of hazardous
constituents in the sludge matrix will generally be
dictated by chemical usage and the type of
operation(s). However, these are not the only factors
influencing waste properties and the requirements for
additional sludge treatment. Plant practices generally
governing source control (i.e., material usage,
transfer, segregation, packaging, and/or storage) can
play an important role in any treatment strategy
encompassing sludge reduction, purification, and/or
immobilization. Many of the wastewaters contributing
to the sludge matrix have the potential for containing
variable concentrations of soluble organics. These
58
-------
Figure 8-2. Waste management strategies having application to wastewaters.
Wastewaters
Containing
Preferential
Pollutant
Removal and
Reuse
s-TOC
Air Stripping
Steam Stripping
Precipitation
Hydrolysis
Oxidation
UV
Adsorption
Absorption
Biological
Oxidation
Thermal
Distillation
1
Preferential
Pollutant Removal
for Detoxification
and/or Potential
Reuse.
organics can originate from residual oil and grease,
cleaning solutions, metal finishing operations, and
chemical detergents. These organics can be mobile in
aqueous media as well as attenuated and
concentrated in the sludge matrix. The resulting
properties could pose problems relative to optimum
treatment performance, sludge stabilization, and
disposal costs. As such, optional strategies should
focus either on liquid/solid phase separation strategies
and/or immobilization technologies. An overall strategy
is summarized in Figure 8-3. Some of the operating
considerations impacting selection and performance
are summarized below.
Liquid-Solid Phase Separation
As previously noted, the total solids content as well as
the chemical loadings of heavy metal sludges can
vary significantly. The organic content will typically
represent the volatile fraction, but the presence of
higher molecular weight aliphatic and aromatic
organics cannot be discounted. For example,
phenolics can be found in many sludges as a result of
their use as a biocide in many soluble oils which are
partially absorbed during the chemical precipitation
process. '
Liquid-solid phase separation strategies can focus
primarily on optimum volume reduction, but this
approach may not ensure optimum immobilization of
the pollutants. Ideally, soluble organics should be
removed before the chemical precipitation phase;
however, if this approach is not feasible, reduction
strategies should be assessed^ in terms of reducing
volume as well as hazards potentially characteristic of
the constituents comprising the sludge. In this regard,
emphasis should be placed on technical options which
are effective in optimizing, the removal of entrained
liquids, whereas liquids can be defined in this context
as water as well as volatile solvents.
Moisture removal by mechanical means (e.g.,
vacuum, centrifugal, and/or pressure dewatering
systems) can prove effective in reducing volume;
however, the entrained organic content is generally
concentrated, jn some cases, dewatering can
increase pollutant concentrations to an extent where
59
-------
Table 8-7. Typical Properties and Content
of Metal Hydroxide Sludges
Constituent/Characteristic
Cadmium
Hexavalent chromium
Nickel
Cyanide (complexed)
Copper
Zinc
Aluminum
Arsenic
Barium
Mercury
Silver
Lead
Selenium
Tin
Chromium (total)
Titanium
Iron
Phenol
Volatile organics
Fluoride
Ammonia
Water
Phosphates
Detergents
Alkalinity
T.O.C.
Sulfide
Specific gravity
DH
Cone. Range (%)
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
0-50
1.0-1.5
5-14 units
the resulting sludge properties are more hazardous
than the waste originally generated.
Unlike moisture removal by mechanical means, the
option of thermal drying relies on heat to evaporate
moisture and other volatile liquids producing as a by-
product a dry, granular solid. Upstream processing
can create chemical and physical variations in particle
size, level of impurities, and capillary size, each
variable having distinct effects on the residual by-
products and drying performance. A number of new
innovations in drying are making this option attractive
and optimum in terms of preventing fouling, reducing
residence time, and off-setting energy costs by
increases in disposal costs. The technology can have
wide applications yielding a number of benefits if the
chemistry of the sludge and the factors influencing the
mobility of water and/or volatile constituents are well
understood. Consider the following benefits achievable
with drying:
Filter cakes can be reduced an additional 60 to 80
percent by volume optimizing reduction of waste
volume.
The dried residues will display physical properties
amenable to direct disposal via landfill.
Purification techniques requiring metal reclamation
and reuse can be made feasible, minimizing
requirements for treatment.
The dried residues can be treated in a manner
that will remove volatile organic constituents to
levels that will meet EPA's land disposal
standards including the TCLP performance
standards.
The metal constituents found in the sludges are
effectively immobilized and amenable to potential
delisting of hazardous characteristics.
Disposal costs can be significantly reduced by as
much as 60 to 70 percent.
Pay-out analysis shows capital investment
recovery within relatively short periods of time.
The risks associated with large volumes of waste
being shipped off-site will be significantly reduced.
Off-spec charges and the potential need for
solidification are eliminated.
Stabilization/Solidification
In light of the stated regulatory trends,
stabilization/solidification (S/S) technologies have been
applied with inorganic and, to a limited degree,
organic wastes with the primary goal of ensuring the
safe, ultimate disposal of hazardous waste through
landfilling or other applicable alternatives. The primary
goals of S/S, irrespective of methodology, are:
To improve the handling, load bearing capacity,
and physical characteristics of the waste.
To decrease the surface area across which
transfer or loss of contained pollutants can occur.
To limit the solubility of any pollutants contained in
the waste.
To detoxify and/or remove pollutants of concern.
S/S technologies utilizing cementitious/pozzolanic
reagent(s) have been successful in attaining the
stated goals for wastes categorized primarily as
inorganic. S/S technologies have reportedly
demonstrated limited success in preventing the
dissolution of organic constituents into the
environment. This is not to say that an organic waste
cannot be physically solidified; it simply implies that
conventional S/S applications have had limited
success in actually stabilizing an organic; whereby
stabilization may be defined as a process of fully or
partially bonding organic waste by addition of a
60
-------
Figure 8-3. Waste management strategies applicable to metal hydroxide sludges.
Consolidate Sludge on the
Basis of Hazard
Characteristics
Optimize Liquid-Solid
Phase Separation
Conventional
Application
lime
kiln dust
cement
alkali/pozzolanic
Cement/Polymeric
Application
20-50%
Reduction
Thermal Drying
Continuous
Semi-Continuous
I Encapsulation
60-80%
Reduction
Extraction for
Metals Recovery
Consolidate sludge on the
Basis of Hazard
Characteristics
Thermal
Degradation
Pelletize/
Densification
Chemically
Stabilize
and Delist
Purification/
Reuse
Detoxification
supporting medium, a binder, or, if necessary, a
modifier. In the context of the stated goafs, a
stabilization process will involve a chemical interaction
between the waste and a binding agent. Few
incentives' for the development of stabilization
techniques for organic waste have been available until
recently promulgated regulatory trends have made it
economically attractive to optimize the performance
and applicability of stabilization technologies for
organic waste.
With respect to organic waste, literature provides
limited references to the potential mechanisms of
bonding or of interferences to bonding in stabilized
waste. The following mechanisms are generally cited
and utilized:
macroencapsulation;
microencapsulation;
adsorption; and
physical/chemical fixation.
With organics, the stated mechanisms may involve
one or more of the following bonding mechanisms:
Physical entrapment within an impermeable
coating which is indefinitely stable under physical
and chemical conditions. This mechanism, which
is strictly questionable, would appear to have
limited applicability in attaining EPA's proposed
performance standards.
61
-------
Physical entrapment in which the waste is
heterogeneously, but fairly, dispersed within a
solid matrix. The concepts of microencapsulation,
which generally entails blending of incompatible
chemicals, warrant additional evaluation in light of
recent developments involving cement/polymer
techniques.
Chemical fixation which, unlike microencap-
sulation, will rely on chemical interaction varying
from the relatively weak London dispersion forces
of two non-polar materials to very strong chemical
bonds.
Fixation which involves dispersing a waste in a
porous solid matrix and relies on physical
adsorption (London dispersion or Van der Waals
forces) or chemisorbtion (formation of chemical
bonds).
Colloidal dispersion of a waste in a solid. This
combination of microencapsulation and chemical
fixation techniques warrants additional evaluation
in terms of defining the mode of bonding and the
factors influencing intermolecular interactions or
chemical bonds.
Polymerization and waste interaction allowing for
the generation of solid hydrophobic material. This
concept would appear applicable to the inclusion
of unreactive waste materials. Expanding this
concept in line with conventional S/S concepts
warrants further development.
With each stabilization strategy, a major factor
influencing performance is the chemical content of the
waste. One of the problems generally encountered in
developing a stabilization process centers around the
complexity and variability of constituents and their
respective properties under the conditions of each
treatment scenario. As an example, petroleum refining
products contain numerous and varied intermediate
and finished products, including but not limited to oil,
benzene, butadiene, coke, kerosene, paraffin wax,
and phenol. Once the waste properties have been
identified, individual mechanisms can be developed in
a manner that will produce a stabilized product
displaying properties meeting EPA's performance
standards for land disposal.
Additional information which must be surmised from
waste characterizations will include data quantifying
hazard potential. In this regard, evaluated strategies
should quantify issues pertinent to waste stability, free
liquid generation, gaseous emissions, material
handling, reactivity, toxicity, ignitability, chemical
compatibility, the need for liquid-solid and/or liquid-
liquid phase separation, and the need for chemical
pre-treatment.
With the presence of organics in a sludge matrix, the
majority of the constituents of concern are generally
volatile in nature. As such, developmental activities
need to account for factors which could inhibit the
application of conventional S/S technologies, such as:
material handling requirements;
reagent selection and dosage;
mode of reagent application;
potential for chemical waste interaction;
pretreatment of waste lending itself to pollutant
removal and/or detoxification; and
verification of product specifications and bonding
mechanisms.
For the purpose of a comparative analysis, the results
attained after dewatering, solidifying, and drying a
control residue containing a high concentration of
volatile organics and water were identified in terms of
changes in total solids and residual volatiles. The
results are schematically illustrated in Figures 8-4 and
8-5.
Solvent-Laden Residues
Solvents comprised of alcohols, amines, ketones,
esters, and other aliphatic/aromatic hydrocarbons
have a number of principal end-use markets
encompassing paints, coatings, inks, process use,
metal cleaning, dry cleaning, and adhesives.
Applications generally include aerosol propellants,
carriers for coatings, disinfecting agents, reaction
medium, chemical intermediates, and dissolved
mediums for cleaning. The wastes generated from
these applications include contaminated inerts (rags,
filters); residues from the manufacture of paints and
inks; spent solvents from dry cleaning, parts
degreasing, and electronic manufacturing; semisolid
recovery/distillate residues: wastewaters containing
soluble solvents; unused inventory; and contaminated
soils. An overall control strategy for solvent wastes is
depicted in Figure 8-6. Waste management practices
applicable to solvent-laden residues are summarized
in Figure 8-7.
Distillation, whether it involves fractional or batch
processing, has found wide application for the
recovery of solvents. Many of the byproducts,
characterized as bottoms or still residues, still display
hazardous characteristics reflecting the presence of
residual concentrations of solvents. The solvent
fractions typically found in these residues can vary
significantly, raising issue with environmental con-
cerns dealing with waste compatibility, mobility,
ignitability, and toxicity. Many of the commonly utilized
solvents characteristically display relatively high water
solubilities causing concern over their effects on
TCLP results. The properties of these residues are
restricting land disposal and dictating thermal
destruction. As an alternative to incineration, the
62
-------
Figure 8-4. Percent total solids as function of treatment.
Drying
Solidification
Dewatering
Control
20
40
60
80
100
Figure 8-5. Residual volatile organics as function of treatment.
Control
Air Stripping
Steam
Stripping
Dewatering
Drying
Solidification
20 40 60
Volatiles (Weight Basis)
80
100
63
-------
Figure 8-6. An overall strategy applicable to the control
management of solvent-laden residues.
Source control
Control purchasing
Hazard awareness
training
Tracking chemical
distribution and
usage
General housekeeping
Assess potential for
chemicai substitution
Accountability
Segregate feedstock
on the basis of
compatibility
Treatment
Blend for off-site
purification/reuse
Segregate and blend
for off-site fuels
Segregate and blend
for off-site
detoxification
Blend for treatment
and volume
reduction
Safe disposal
Recycling
Return unused
chemicals to
vendors
Assess need on waste
exchange
Assess potential reuse
applications at other
plants
Segregate for off-site
product reclamation
Segregate for reuse
as fuel supplement
whereas others require that the physical properties be
modified to allow for direct application. Equipment
evaluation criteria will take into account moisture
content, bulk density, particle size, pH, boiling point,
temperature, abrasiveness, explosive limits, and
sensitivity to heat. Among the units available for
treatment are the:
Blaw-Knox Vacuum Drum Dryer;
Luwa Thin Film Drying and FILMTRUDER Polymer
Processing Systems;
Nara Paddle Dryer/Processor;
HoloFlite Processor; and
VRS System.
There are a number of other systems available, each
dictating evaluation in terms of optimum treatment
performance.
In terms of removing all residual solvents and
eliminating the hazard characteristics, drying can
prove feasible; however, each application is subject to
verification. Some of the strategies applicable to the
solid by-products of drying are summarized in Figure
8-9.
mobility concerns can be eliminated by preferentially
removing solvents that are found in the bottoms matrix
as mechanically and chemically bound liquid. One
option for removing these liquids deals with recent
innovations in drying with and without agitation.
Innovations with indirect treating sources, i.e., thin-film
dryers, have made this- option feasible for
devolatilizing very viscous residues including polymers
and adhesives. In the context of a master strategy for
solvent-laden residues, drying does compare favorably
with alternative thermal destruction techniques
especially if the treated byproducts can be reclaimed.
A typical strategy is referenced in Rgure 8-8.
With drying, it is important to remember that heat
transfer varies with each phase of drying. In retrospect
of the objective requiring optimum reduction and
solvent removal, the "system must compensate for the
operating conditions typically experienced after the
critical moisture point (i.e., the point in the drying
cycle where the drying rate drops and the liquids
which wetted the solids disappear). The falling rate
can be controlled by the physical properties of the
entrained liquid and solids, capillary size, glazing,
pressure gradients between trapped liquids, and
vapors. Agitation can enhance treatment performance
by rapidly bringing particles into contact with the heat
transfer surface.
There are a number of commercially available dryers
having application to hazardous waste residues. Some
of the units are capable of treating wastes directly,
Packaged Laboratory Chemicals
A number of waste categories representing small
quantity hazardous wastes can be very costly to
package, control, and dispose of. This category of
waste, often referred to as packaged laboratory
chemicals, is also being scrutinized in terms of
verifying contents and conformance with the
acceptance criteria of a commercial TSD facility. The
costs for disposal can be significantly reduced by
instituting a control management program that will
allow constituents to be segregated on the basis of
their properties, composition, and hazard. Control
management strategies are summarized in Figure 8-
10.
Within this category are problems generally associated
with the disposal of small containers of solvent. A
typical control management strategy having
application to these wastes is referenced in Figure 8-
11.
Waste O//s and Oily Residues
Waste oils, for the most part, can be categorized as
soluble and insoluble. The degree of contamination
and their potential hazards generally will be dictated
by usage and control management practices.
Common contaminants may vary within one or more
of the following chemical categories: metafiles, volatile
halogenated and non-halogenated organics,
64
-------
Figure 8-7. Waste management practices applicable to solvent-laden residue.
Characterize
Residue on the
Basis of Content,
Matrix and Mobility
Reclamation N
Reuse J
~L
Halogenated Aromatics
Non-Halogenated
Aromatics
Halogenated Aliphatics
Non-Halogenated
Aliphatics
Semi-Volatile
Halogenated
Non-Halogenated
Combined Mixtures
Solid
Content
Ash
Flash Point
BTU/lb
Layering
Viscosity
Reactivity
Treatment to
Enhance
Recovery
Elimiric-i Concerns
Relating , Volatility
semivolatile organics, toxic organics, and inorganic
salts.
Strategies typically will focus on phase separation with
the objective of purifying the oils for fuel supplements,
re-use, and/or alternative industrial application. Some
of the applicable strategies are summarized in Figure
8-12.
Summary
This paper provided a number of strategies and
justification for managing and controlling hazardous
and contaminated solid waste. The trends in disposal
costs, available TSD services, and regulatory
legislation are providing the impetus to re-assess
existing practices, to minimize waste generation, and,
wherever feasible, to eliminate hazard potential.
To ensure compliance with new treatment
performance standards, the chemical composition and
properties of a waste need to be well understood. The
chemistry of hazardous waste is becoming a very
sophisticated science dealing with the structure,
composition, and properties influencing the
transformation, mobility, and toxicity of chemical
constituents within a multimedia environment.
Control management must focus on the source as
well as the "end of the pipe." In-plant policies and
procedures should complement treatment in a manner
that yields a control strategy that enhances the
potential for waste reclamation and reduction.
The cost/benefits associated with any one of the
described source control strategies can be easily
recognized. Disposal costs for services involving land
disposal could conceivably triple over current prices
by the mid-1990s. To sustain current price schedules
for residues dictating land disposal through the 1990s,
generators will need to achieve a 60 to 70 percent
reduction in waste volumes typically generated at "the
end of pipe."
65
-------
Figure 8-8. Waste management strategies for solvent-laden residue.
f Waste So.vent ~) > I vSKSro
^ Uquids/Semi-Solids J ^ Recove^euse
L incmerati
* >
^ still Residue
1 Viscous Sludges ]
\ -*
^ A. " uryiny
Content 0.5-30% '
J| Pretreatment 1
-J
^ (_ Treatment J
^ Water J)
. Solvent
* Reuse/Disposal
v ^
r
, ,
[ Solid ]
1 Soil/Debris I 1 Reuse/Disposal 1
Figure 8-9. Strategies applicable to solid by-products of drying operations.
Sludges
Viscous Paints,
Adhesive
Inks
nissions /
Soils ^
tydroxide
s,
oatings,
Debris i
^
A
\ nt
k * u>
^
Cv
vinn h DfV Solids
Vastewater^
Recovery/Reuse Options
Extract, Metals
Pigment Reuse
Resin Recovery
Aggregate Reuse
Feedstock Reuse
Optional Pretreatment
Disposal Options
Direct Landfill
Pelletize, Encapsulate and
Landfill
Extract, Burn as Solid Fuel
Pelletize, Burn as Solid
Fuel
Direct Incineration
Aggregate, Stabilize
66
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Figure 8-10. Control management strategies for packaged
laboratory chemicals.
Combine compatible liquids
Where feasible blend in 55-gallon
containers
Segregate chemicals on the
basis of chemical content
and hazard potential
Corrosives
Oxidizers
Flammable solids
Reactive substances
Organic solids
Packaging guidelines
Remove and bulk consolidated liquids where feasible
Minimize void space in bottles containing chemicals
Optimize placement of containers in each drum
Establish satellite segregation and consolidate at the source
Figure 8-11. Control management strategies for containers of waste solvent.
Segregate containers on the basis of properties, chemical
content and compatibility
1
Liquids
Segregate halogenated and nonhalogenated liquid solvent
Optional removal of immiscible water layers and/or
suspended solids
Blend compatible mixtures of solvent in 55-gallon containers
and/or tanks
Resulting blends shipped off-site for
- Reclamation
- Synthetic Fuel
- Treatment
Semi-Solids/Solids
Segregate halogenated and nonhalogenated residue
Optional removal of free liquid
Sub-segregate categories on the basis of flash point,
chemical content and toxicity
Blend compatible residues
Resulting blends and/or individual containers:
- Off-site reclamation
- Off-site incineration
- Off-site treatment
followed by stabilization
67
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Figure 8-12. Management strategies applicable to residues categorized as waste oils and oily residues.
Chemical Properties
Metallics
Volatile Organics
Semi-Volatiles
Toxic Organics
Salts
Characterize Residues
_£
Segregate on the Basis of
Physical/Chemical Properties
Soluble Oils
Emulsified Oils
Insoluble Oils
Oily Sludges
PCB-Contaminated Oils
Liquid/Solid Phase
Separation
Decantation
J C
Filtration
Membrane
Treatment
Distillation
Devolitalization J
Stabilization
Biodegradation _J
Extraction
Fuel Blending
Extraction
jr
Distillation
j f Absorption j f Chemical | [
' v > (Treatment J ^
Halogenation
1
1
r
Thermal
Treatment
(f Purification ^)
(^ Detoxify ^)
Fuel
Blending
Reclamation/
Reuse
I [ Recycle ]
References
1. Environmental Protection Agency, 40 CFR Part
268, Appendix III List of Halogenated Organic
Compounds Regulated Under Section 268.32.
2. Environmental Protection Agency, 40 CFR Part
264, Appendix IX Groundwater Monitoring List.
3. Environmental Protection Agency, 40 CFR Part
372 SARA, Toxic Chemical Release Reporting,
Community Right-to-Know.
4. Environmental Protection Agency, 40 CFR Volume
51, No. 114, Part 261.24, June 13, 1986 Proposal
TCLB.
5. Stanczyk, Thomas F. "Reduction Strategies for
Solvent-Laden Residues, Heavy Metal Hydrozide
Sludges." 1987 Technical Strategies for
Hazardous Waste Production and Control,
Government Institutes.
68
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Chapter 9
Waste Reduction for Chlorinated Solvents Users
E. Richard Randolph
Dow Chemical, USA
Midland, Ml 48674
Numerous examples have shown that waste reduction
programs result in a cleaner environment, less worker
exposure to chemicals, and significant savings in fuel,
feedstock, and environmental control costs.
To illustrate some principles of waste management,
internal and external efforts to reduce waste from the
use of specialty chlorinated solvents (including a
description of in-house recycling), factors influencing
solvent consumption, and issues in solvent waste
disposal are described.
Waste Reduction: Background
Dow has practiced waste reduction since the 1960s
when Chief Executive Officer Carl Gerstacker
developed a pollution control plan that called for
employee involvement and rewards for achievement.
He sought to improve yields, reduce waste, and find
ways to use waste. Waste disposal was a last resort.
Significant dates in the regulatory and legislative
history of waste reduction include: 1976, when the
Environmental Protection Agency listed waste
reduction at the top of a preferred hierarchy for waste
management; and 1984, when Congress defined the
desirability of waste reduction as a national policy.
In 1987, the internal efforts that grew from
Gerstacker's plan were grouped under a program
called WRAP - Waste Reduction Always Pays.
The importance of a plan such as WRAP is that it is
long-term, and formalizes past, present, and future
waste reduction efforts to track progress and chart a
course (see Figure 9-1). Goals are to:
Reduce waste in all media.
Create a disposition toward waste reduction.
Provide incentives to reduce waste.
Recognize excellence in waste reduction efforts.
Save money (including avoided costs).
Lessen future liability.
Figure 9-1. WRAP flow chart.
Develop historical benchmark for each process
Inventory all losses to air, water, land (quantity and quality)
Identify source of losses
Prioritize (volume and screening method)
Determine cost effective actions
Allocate resources
Implement actions
Document and report progress routinely
Communicate internal and external
Plan for future reduction
Waste reduction can be defined as:
Any in-plant practice or process that avoids,
eliminates, or reduces waste so as to reduce
environmental risk to any media.
The treatment, reuse, or recycling of any material
that reduces the volume and/or toxicity of waste
prior to final disposition.
69
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The Louisiana Operations Division - a large,
diversified, manufacturing division - provides excellent
examples of success in waste reduction. In the past
decade, hydrocarbon emissions dropped by 92
percent and chlorinated hydrocarbon discharges to
water dropped by 98 percent, while production
increased from about 8 billion to 12 billion Ib/yr.
The division utilized techniques such as improving the
purity of raw materials, improving instrumentation,
using on-stream analyzers, using process analysis by
statistical methods, and improving maintenance.
Trends in Chlorinated Solvents Use
Specialty chlorinated solvents include 1,1,1-
trichloroethane, trichloroethylene, methylene chloride,
and perchloroethylene. The diverse applications for
these products include metal cleaning (by means of
cold cleaning and vapor degreasing), dry cleaning,
chemical processing, and production of fluorocarbons,
aerosols, paint removers, adhesives, coatings/inks,
and blowing agents.
The demand for metal-cleaning solvents far outweighs
the demand for chlorinated solvents for any other
application (see Figure 9-2). It is more than twice the
demand for dry cleaning solvents and three times the
demand for fluorocarfaon production solvents. Dry
cleaning and fluorocarbon production are the second
and third largest applications for chlorinated solvents,
respectively.
Metal-cleaning solvents represented 38.2 percent of
the total demand for chlorinated solvents in 1984, and
34.6 percent of the total in 1987. Although demand for
metal-cleaning solvents dropped 139 million Ibs in
those three years - a decline disproportionate to the
194-million-lb drop in total demand - metal cleaning
still is the most significant application for these four
chlorinated solvents in the United States.
Conservation and efforts to encourage more efficient
use of solvents have contributed to both the decline in
demand for all virgin chlorinated solvents and the
decline in use of virgin chlorinated solvents for metal-
cleaning applications.
Recycling Through Contract Reclamation
Many chlorinated solvents users hire companies with
the technology to reclaim solvents from waste
sludges. The growth of contract reclamation is
illustrated in Table 9-1.
When recycled solvents enter the marketplace, the
demand for virgin solvents drops correspondingly.
Recycled solvents come primarily from metal-cleaning
applications.
Table 9-1. Contract Reclamation
% of all solvents
Pounds reclaimed (in users buying
Year millions) reclaimed solvents
1977
1982
1986
1990
69
147
268
310 (estimate)
20-25
75-80
As shown in Figure 9-3, the demand for virgin
chlorinated solvents was sluggish between 1971 and
1980 and has fallen since 1980. That decline
corresponds almost directly to the increase in total
pounds of reclaimed solvents on the market since
1980.
Some of the characteristics of contract reclamation
are that it:
Can provide analysis.
Can provide partially or fully restabilized recycled
solvent.
Is an environmentally secure process.
Allows for disposal to fuel blending.
Recycling Through In-House Reclamation
While the contract reclamation industry was growing,
chlorinated solvents users also were finding ways to
recover solvents in-house. In 1983, 52 percent of the
customers that Dow knew were using chlorinated
solvents, were recovering in-house. That figure was
up to 64 percent in 1987.
The use of in-house stills to recover solvent and
concentrate waste typically results in up to a 20
percent reduction in solvent use. In-house solvent
recovery is tantamount to source reduction because it
eliminates a need for virgin material.
Some of the characteristics of in-house reclamation
are that:
Solvent usually is not cross-contaminated.
Recycled solvent can be blended with virgin
solvent for reuse.
Solvent must be analyzed for stabilizer strength.
Waste sludges go to a disposal contractor or
reclaimer.
Distillation recovery equipment falls into three
categories: process stills, in-house solvent recovery
equipment, and thin-film evaporators. In addition, the
vapor degreaser can be used as a quasi-still by
means of the boil-down procedure (see Appendix A).
Process stills are used in conjunction with vapor
degreasers. Dirty solvent from the sump of the
70
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Figure 9-2. Applications/end uses for specialty chlorinated solvents.
1984 Volume
(MM Ibs.)
800
700
600
500
400
300
200
100
754
344
208
186
203
137
Metal Dry- Fluoro-
Cleaning cleaning carbons
Produc-
tion
Aerosols
Chemical
Processing
Industry
Paint
Removers
Other
degreaser is pumped to the still for distillation, then
returned to the degreaser's offset clean solvent
storage tank.
A degreaser with a still does not have to be shut down
and cleaned ,to remove contaminants as often as a
degreaser without a still. Periodically, the still is
opened and the sludge removed while the degreaser
continues operating. This process is called continuous
distillation and can produce a waste that is
approximately 25 to 50 percent solvent.
Process stills are often steam heated, but can also be
electrically heated or steam fired. Their recovery rates
are expressed in gallons per hour, and typically run
from 30 to 200 gal/h. About 62 percent of Dow's
larger customers recovering solvents on-site use
process stills.
In-house solvent recovery equipment offers a
specialty technique for minimizing solvent waste and
eliminating the need to send spent solvent to an
outside reclaimer. To recover solvent, spent solvent is
collected and stored until enough accumulates to fill a
still. The contaminated solvent is pumped into the still,
distilled, and recovered in drums or storage tanks.
This is called batch distillation and removes 70 to 95
percent of the solvent in the waste.
Larger units use the same type of equipment as
process stills, except that they are not necessarily
used in conjunction with vapor degreasers.
Some newer, small-capacity units (5 to 25 gal per
batch) are electrically heated and recover solvent over
a long period, typically about eight hours. Based on
hundreds of calls on customers over the past four
years, Dow estimates only about one to two percent
of customers recovering solvents on-site are using
these mini-stills.
71
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Figure 9-3. U.S. demand for chlorinated solvents.
2,500 r-
2,000
1,500
MMLb
1,000
500
Total Virgin
Virgin MC
Reclaim
1971
1974
1977
1980
1984
1987
1990
Thin-film evaporators are used for high-volume solvent
recovery. Their application is primarily for continuous
feed, and capacities range "from 50 to 500 gal/hr.
Solvent recovery is 90 to 95 percent.
Recovered solvent fits into one of these three
categories:
Clean solvent.
Clean solvent with the measured addition of acid
acceptor.
Clean solvent, analyzed for inhibitor content and
restabilized with both acid acceptor and metal
stabilizers as required.
The latter two categories usually are obtainable only
through contract reclaimers.
The recovered solvents that are obtained from in-
house distillation usually can be used directly in the
cold cleaning or vapor decreasing process as a
replacement for some virgin solvents. However,
because the quality of recycled solvent can vary, it
should be monitored by analysis and used only as a
blend with virgin solvent. The user of either in-house
or contract-recovered solvent should be aware of its
relative quality to be sure it is suitable for the intended
use.
Fortunately, in-house distillation is not often subject to
cross-contamination, and blending with virgin solvents
during reuse should keep stabilizers within satisfactory
limits.
In some cases, however, it is necessary to restabilize
recycled solvents in-house when inhibitor depletion is
excessive and unavoidable. An example would be to
add acid acceptor to trichloroethylene that has been
depleted by carbon adsorption recovery. Some, not
all, stabilizers are provided commercially in a safe and
effective manner.
The quality of recovered solvents may vary for
reasons including stabilizer depletion and cross-
contamination with other solvents or compounds.
Problems that can occur because of improperly
stabilized solvent include:
Dilution of fresh solvent, which can shorten
solvent life.
72
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Reduced acid acceptor content. This can
decrease the margin of safety before an acid
condition develops in cases of stress.
Reduced metal stabilizer content, which
decreases or eliminates protection from corrosion.
Corrosion produces acid that degrades solvent
and consumes acid acceptor.
Excess stabilizer content, a potential flammability
hazard.
Improper stabilizer ratio, which reduces the
effectiveness of metal stabilizers.
Contaminated solvent. Such contaminants as
aromatics in methylene chloride and 1,1,1-
trichloroethane in trichloroethylene can cause
reactions that result in an acid condition,
especially in the presence of aluminum.
Excess water. This shortens solvent life, causes
greater vapor loss, and creates corrosion and/or
spotting on the work.
Depending on the equipment utilized and the nature of
the production process, waste solvents and residues
from in-house distillation are sent out for further
reclamation or disposal (see Figure 9-4). As a broad
rule of thumb, solvent wastes containing up to 30
percent oil are forwarded to contract reclaimers.
Solvent wastes containing 30 to 90 percent oil are
sent to fuel blenders through a waste broker. Wastes
with more than 90 percent oil are sent directly to
disposal via thermal destruction.
Fuel blending is by far the most common and most
cost-effective way to dispose of solvent waste.
Because the hazardous waste-burning facility usually
is large, it works on a bulk-fuel basis. Therefore, the
average waste generator does not deal directly with
the burner, and probably not even with the large bulk-
fuel blender that is supplying that burner. Rather, the
average generator deals with an intermediary such as
a reclaimer, waste broker, or solvent distributor who
can bulk up the waste volumes economically.
Some chlorinated solvents users enhance solvent
recovery with steam sparging, stripping, or specialized
collection systems such as double distillation. Such
techniques, practiced on large quantities of waste,
allow chlorinated solvents users to reduce their waste
production substantially and fall more in the realm of
waste management than waste reduction.
The major incentive to practice solvent reclamation is
to save money. For the same reason, solvents users
are insisting on tighter machines that waste less
solvent, and are looking for even more ways to use
solvent more efficiently.
Waste Reduction: Customer Assistance
In 1976, the Environmental Protection Agency
contracted a study to support new source
performance standards for solvent metal-cleaning
operations.
Under that contract, K.S. Surprenant and D.W.
Richards identified and quantified emission control
techniques being practiced at that time. They included
use of covers, liquid absorption, carbon adsorption,
use of refrigerated freeboard chillers, refrigeration
condensation, and good operating techniques.
The study indicated that inefficient cold cleaning and
vapor degreasing were responsible for a large portion
of the solvents that were emitted to the atmosphere
and therefore wasted. Since there were many
techniques to improve efficiency and reduce waste
during these operations, the study reinforced the need
and commitment to assist solvents users.
The effort has become the Waste Reduction
Assistance Program, which has four elements: field
support services, product stewardship, training and
seminars, and literature.
Field Support Services
In 1986, 44 percent of the calls made by chlorinated
solvents technical service personnel related to waste
reduction. In 1987, 53 percent involved waste
reduction. Waste reduction-related field support
services include:
Process troubleshooting, including visiting the
plant to identify problems, as well as handling
inquiries over the phone.
Vapor degreaser inspections to determine if there
are problems with the design or maintenance of
the degreaser or associated equipment.
Recommendations covering all phases of
degreaser operation, including heat balance, water
handling, and parts handling.
o Engineering consultations involving cleaning of
metal and design of equipment.
Waste- and emission-reduction recommenda-
tions.
Product Stewardship
Examples of product stewardship as it relates to waste
reduction are locating and monitoring vapor
concentrations in the workplace and suggesting ways
to reduce them. Monitoring includes taking halide
meter readings and. dosimeter readings, as well as
73
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Figure 9-4. Hazardous waste disposition flow chart.
conducting professional industrial hygiene surveys in
some cases.
solvents and reduces the volume of solvents requiring
recycling or disposal.
Training and Seminars
Training is one of the most important facets of waste
reduction. Topics include product application,
maintenance, the theory of vapor cleaning,
environmental and regulatory updates, and safety.
Programs can take place in groups or one on one and
are available to distributors of chlorinated solvents,
distributors' customers, direct customers, and the
producer's own field personnel.
Literature
Waste reduction is covered in solvent Material Safety
Data Sheets, Product Stewardship Manuals,
application brochures, newsletters (see Appendix B),
and other publications.
These four elements, practiced together, constitute a
formidable solvent-management- program that is much
stronger than any one of them practiced alone.
Factors Influencing Solvent Consumption
Most of the techniques for reducing waste during cold
cleaning and vapor degreasing are easy to follow and
improve the efficiency with which the operations use
solvents. Every pound of solvent conserved results in
the equivalent pound of reduced" demand for virgin
Cold Cleaning
Good operating practices are essential to curb solvent
consumption during cold cleaning - and they are
mostly a matter of common sense.
To minimize evaporative losses:
Use covers.
Use a water layer on top of the solvent where
acceptable.
Use a coarse spray or solid stream of solvent
instead of a fine spray.
Control ventilation.
Place wipe rags in a closed container and use
them again wherever possible.
Minimize open surface area.
Use a deep tank with a high freeboard.
Use specially designed containers with automatic
lids and drains.
Drain parts properly to capture as much of the
solvent as possible.
74
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Don't use compressed air sprays to blow dry parts
or to mix cleaning baths.
To reclaim solvent:
Capture and distill any waste.
If a vapor degreaser is available that uses the
same solvent, the waste cold cleaning solvent
simply can be added to it.
Vapor Degreasing
Reclamation of reusable solvent from waste sludges is
important, but only about 15 to 30 percent of the
solvent used for metal cleaning by vapor degreasing
becomes waste. The other 70 to 85 percent is
eventually lost to evaporation - after multiple uses in
the system - through inefficient operation and
maintenance of the degreaser and associated
equipment. Techniques to reduce overall emissions
from a degreaser, and to fine tune degreaser
operation, conserve some of that 70 to 85 percent.
Specific suggestions for minimizing solvent loss and
reducing the cost of using solvent during vapor
degreasing fit into seven general categories.
1. . Ensure proper degreaser operation.
Leave the unit on to maintain the vapor level
unless it will not be in use for long periods of time.
Do not expose heating coils to vapor. This
could result in a breakdown of the solvent and
corrosion problems in the unit, in addition to loss
of solvent.
Provide proper maintenance. Remove visible
corrosion and repair leaks. Repairing leaks alone
can result in up to a 50 percent reduction in
solvent loss.
Use and maintain appropriate design and
safety devices. These devices include solvent
level controls and vapor, condenser water, and
boiling sump thermostats.
2. Maintain proper heat balance.
Use the least amount of heat required to keep
the solvent at a slow boil and to give adequate
vapor production. High heat provides only rapid
vapor recovery, not improved cleaning.
Regulate the cooling level either by adjusting
the temperature of the cooling water or by altering
the flow rate of the cooling water. The vapor level
should balance at the midpoint of the condensing
coils; a fluctuating vapor level pumps the vapor-air
mixture out of the unit.
3. Minimize vapor diffusion.
Reduce exhaust velocities to provide adequate
protection of workers, yet not draw vapors out of
the degreaser. Adjusting exhaust velocities can
achieve up to a 50 percent reduction in solvent
loss.
Cover open-top degreasers, especially during
idle times. This is the most significant solvent
conservation method; it can reduce solvent loss
up to 55 percent. Sliding covers do not cause
turbulence when moved, unlike hinged covers.
Extend the freeboard. Units with freeboard
heights that are 40 percent of the width of the
degreaser can use up to 40 percent more solvent
than units with ratios of 75 to 100 percent.
Use cold traps, an upper set of very cold coils
that cool the air above the vapors. Properly used,
cold traps provide a dense air blanket that helps
prevent vapor escape.
Cover the water separator to prevent any
possible vapor loss.
Check the water jacket for proper water flow and
temperature on the outside of the degreaser to
prevent migration of hot vapor up the side walls,
Prevent drafts over the degreaser. Fans, air
conditioners, heaters, windows, doors, general
plant air movement, and equipment movement
can blow the vapor-air mixture out of the
degreaser. Locate the degreaser to minimize
natural drafts or use baffles to prevent upset of
the vapors and achieve up to a 30 percent
reduction in solvent loss.
Also, vapor control with lip vent or hood exhaust
may be too forceful, so reduce exhaust velocity
to the minimum level that provides proper vapor
control in the working area.
Some semi-closed machine designs tend to
channel and reinforce air current through the
machine, especially if power-exhausted.
Rearranging air movement in the room helps to
eliminate the windtunnel effect.
4. Minimize water contamination.
Avoid adding water. This is important to prevent
depletion of stabilizers, which results in solvent
decomposition and corrosion from acid formation
by hydrolysis. Condenser coils, cold trap coils,
and the water jacket can be too cold, resulting in
75
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condensation of atmospheric moisture. Also, wet
parts can introduce water, particularly as a
component of water-soluble cutting oils.
Dewater the solvent. A water separator should
be able to reduce dissolved water in the solvent.
Also, skim floating water off the top of the solvent,
since this represents excessive water content.
Water and solvent form an azeotrope at boiling
temperatures. The azeotrope has a lower density
and higher diffusion rate than dry solvent vapors
and is harder to contain.
Install a separate water trough for refrigerated
coils. Cold trap coils can build up a heavy dew. A
separate discharge for this condensate is
necessary to avoid introducing the water to the
solvent at a common water separator, which
reduces the water separator's effectiveness and
perhaps could overload its capacity.
5. Establish proper workload handling.
Ensure parts are up to temperature before
removal. The cleaning cycle isn't complete until
the parts have reached the temperature of the
vapor so that condensation has ceased. If
condensation is still forming, solvent carryout will
increase.
When cleaning metal parts with spray, spray
below the vapor zone. Spraying above the vapor
zone generates a vapor-air mixture which is
immediately lost. Also, falling droplets of solvent
disrupt vapor interface, causing more vapor-air
mixing. Spraying below" the vapor zone can
achieve up to a five percent reduction in solvent
loss.
Move the work slowly. (See Appendix C for
instructions on using the stop-and-go technique.)
Control the hoist speed to less than 11 ft/min of
vertical travel and ensure the proper conveyor
speed.
Don't overload the degreaser. Too large a mass
of metal creates inefficient cleaning, excessive
vapor drop, slow vapor recovery, and longer
cleaning cycle, resulting in increased solvent
consumption.
Use properly sized baskets. Large baskets that
fill the area of the degreaser opening create a
piston action when entering and leaving. This
forces vapor out, which creates more solvent-
vapor-air mixing. The basket should have an area
of less than 50 percent of the degreaser opening.
Drain the parts. Solvent not allowed to drain
properly from parts is lost immediately to
evaporation outside the degreaser. Adjust the
spacing in the baskets or the racks so drainage
can occur.
6. Avoid solvent carriers and solvent-absorbent
materials.
This includes such items as ropes, spacers, and
wooden covers. Also, don't clean shop rags or
gloves in the degreaser. Up to five percent
savings in solvent are possible here.
7. Ensure proper solvent condition.
Remove metal fines and parts, sludge, and oil
buildup. Oil content should not go above 25 to 30
percent. Accumulation of metal fines and debris is
one of the major causes of acid degreasers.
Maintain inhibitor levels. Depletion of inhibitor
levels could result in a catalytic breakdown of the
solvent to form hydrochloric acid or metal chloride
complexes, causing corrosion.
Use the boil-down procedure to conserve
solvent. (See Appendix A.)
Modifications to Existing Degreasers
To improve the efficiency with which a degreaser
uses solvent:
Install automatic slide covers.
Increase freeboard height.
Install refrigerated freeboard chillers.
Use carbon adsorption lip exhaust.
Install programmable transporters.
Case Histories
*
Below are two examples of how waste reduction
benefited chlorinated solvents users.
One user consumed 500,000 Ibs of trichloroethylene
per year in eight large cross-rod degreasers with
process stills attached. Waste from the stills was
dumped into a storage tank about every two days,
then collected in drums for disposal. Waste amounting
to about 20 drums a month was collected from each
still.
To minimize waste and reclaim more solvent, thus
reducing costs, the user now pumps the waste from
each still into a holding tank. About every two weeks,
the waste is redistilled and steam sparged to remove
as much solvent as possible.
76
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This procedure reduces waste from 20 drums a
month to five drums a month and reduces virgin
solvent consumption by 15 drums a month.
The second user has a 3 ft-by-5 ft, open-top vapor
degreaser to clean and finish parts from other
companies. Investigation of why the degreaser was
cleaning poorly turned up two problems.
=.. First, the cleaning basket was too large. It was acting
as a piston, pushing out vapors each time it was
lowered into the degreaser. This increased the vapor-
collapse amount and shortened the actual cleaning
time.
Second, the disk-like metal parts were stacked too
closely in the basket, resulting in inadequate cleaning
and solvent entrapment.
Reducing the size of the cleaning basket and stacking
parts differently allowed the user to improve cleaning
and reduce virgin solvent consumption by up to 50
percent by reducing dragout and eliminating the
pumping action from the excessive vapor collapse.
Waste Disposal Issues
Even with the most efficient waste reduction efforts,
waste disposal still is necessary. That means
environmentally sound reclaimers, proper disposal,
and fuel blending/burning - usually in cement kilns or
industrial furnaces - are important.
Many commercial reclaimers manage their wastes as
fuel. In 1981, 18 percent of the waste from
commercial reclamation of chlorinated solvents was
managed as fuel. By 1986, the total was 49 percent.
Some experts would put today's figure at more than
90 percent. Disposing of this type of waste through
fuel blending/burning has become even more
significant as restrictions on disposal in landfills have
increased.
Burning wastes that have been blended into fuel in
cement kilns is particularly efficient. Not only are
wastes used as energy, but the chloride ions from
chlorinated-solvents waste are incorporated into the
cement. Without fuel blending and subsequent burning
in cement kilns, there would .be inadequate
commercial incineration capacity for the wastes that
are being generated in the United States today.
Conclusion: The Benefits of Waste
Reduction
Reducing waste from the use of chlorinated solvents
for metal cleaning means lower solvent costs and
lower waste-disposal costs. The improved efficiency
that helps reduce waste also means improved
cleaning with no increase in solvent usage, another
savings.
Assisting chlorinated solvents users with waste
reduction attracts new customers, maintains existing
customers, reduces their liability exposure, and
maintains the viability of the solvents marketplace - all
economic motives.
Other significant reasons for practicing waste
reduction - to lower worker exposure to vapors, to
reduce solvent loss to the environment, and to comply
with health and environmental laws - also have
economic benefits.
Since many of the benefits of solvent waste reduction
relate to cost savings, more credibility is given to the
assertion that voluntary waste reduction will work.
Waste reduction efforts and long-standing environ-
mental and product stewardship programs
demonstrate a commitment to protecting the
environment. But waste reduction is just one part of
waste management. So safe, permanent waste
disposal and compliance with state and federal laws
still are top priorities.
Yet the bottom line really is that electing to take a
responsible approach to waste reduction makes good
economic sense. WASTE REDUCTION ALWAYS
PAYS.
77
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Appendix A
Procedure for boil down of a still/degreaser
When the temperature in the boiling sump of the still
reaches 194°F (using trichloroethylene as an
example), concentrate the sludge in the still. Turn off
the transfer pump and close the gate valve in the dirty
solvent line. Continue to distill until the liquid level
reaches the recommended minimum level of two
inches above the heating element(s).
Turn off the heat in the boiling sump and allow the
solvent sludge to cool to 90 to 100°F before draining.
Drain the solvent into a 55-gal drum(s). Remove parts,
metallic fines and chips, or other insolubles by
filtration or decantation. Give particular attention to the
area under the heating elements.
Close the drain valve. Open the gate valve in the
solvent line from the degreaser boiling sump to the
still boiling sump. Turn on the transfer pump.
Once the liquid level reaches 2 inches above the
heating element(s), turn on the heat. Add the
necessary virgin solvent to the clean dip of the
degreaser to properly maintain the needed liquid
levels in all chambers of the degreaser and still.
Add the sludge solvent that was placed in the drum(s)
back into the still boiling sump at the next boil-down
when the solvent reaches the minimum level of two
inches above the heating coils.
After the third or fourth boil down, send a sample from
the sludge drum to a laboratory for determination of
nonvolatile content. When the oil concentration
reaches 60 to 70 percent, dispose of the sludge
material in compliance with regulations governing the
disposal of waste products. Thermal destruction
through fuel blending or incineration is recommended.
78
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Appendix B
SOLVENT
Specify Do^ ... For Quality Solvents, Unmatched Technical Support
Vol. 2 Number 1 January 1988
Waste Reduction «> Waste Minimization
The management of hazardous waste in toxicity and/or hazard potential, and can
the United States has become an impor- result in reduced volumes of \
tarn issue to industry, government, en- duced. Wasti
vironmental groups, the public, and Uic_
media. Government reg
mil pro
\anges" include im-
\ procurement prac-
\>uming that lead to
olume, toxicity or
waste products
V refer to modifi-
nent or installs-
( resulting in a
e. The addition
tes that reduce
Solvent
^-SSSS;
'Mss-sw^
*^0SlUeV*eoor
frw
.C°"S
Vse of ta-House Solvent Reclamation
Basing for G~*»--
final recovery.
79
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Appendix C
Stop-and-go technique
The following procedure was developed to reduce
solvent concentration in the ambient air near the
degreaser. It also will reduce the solvent loss from a
degreaser.
Lower the work load into the vapor zone at a slow
speed. Otherwise, an excessive wave formation of the
vapors will push an unnecessary amount of the vapors
out of the degreaser.
The vapors will collapse as the work load enters the
vapor zone. Whenever the vapors have dropped two
to four inches, stop the load until the vapors stabilize
or start to recover. At this point, lower the load further
until the vapors have dropped another two to four
inches.
This stop-and-go method of entry prevents solvent
vapors from being pushed out of the degreaser by the
plunger effect of the work load. It allows maximum
vapor recovery with shorter cleaning cycles.
Once the work load is covered by the vapors, it need
not be lowered further. Maximum area between the
work load and the boiling sump gives optimum vapor
recovery. The work load should never sit on top of the
boiling sump.
Remove the work load in increments of two to four
inches with pauses to allow the vapors to be
entrapped in the freeboard area. This decreases vapor
drag out. Once the work load has cleared the vapor
zone, it should remain in the freeboard area until all
parts are dry and no solvent drips from the work load.
NOTICE:
Dow believes the information and recommendations
herein to be accurate and reliable. However, since
any assistance furnished by Dow with reference to the
proper use and disposal of its products is provided
without charge, and since use conditions and disposal
are not within its control, Dow assumes no obligation
or liability for such assistance and does not guarantee
results from use of such products or other information
herein; no warranty, express or implied, is given nor is
freedom from any patent owned by Dow or others to
be inferred. Information herein concerning laws and
regulations is based on U.S. federal laws and
regulations except where specific reference is made
to those of other jurisdictions. Since use conditions
and governmental regulations may differ from one
location to another and may change with time, it is the
buyer's responsibility to determine whether Dow's
products and services are appropriate for buyer's use,
and to assure buyer's workplace and disposal
practices are in compliance with laws, regulations,
ordinances, and other governmental enactments
applicable in the jurisdiction(s) having authority over
buyer's operations.
80
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Chapter 10
On-Site Reuse and Recycle of Solvents
Robert H. Salvesen
Robert H. Salvesen Associates
Red Bank, NJ 07701
In-plant reuse and recycle of solvents is an accepted
practice in many industries. This paper reviews
practices and equipment which are appropriate for
cleaners of parts and equipment.
Only non-halogenated solvents are discussed. The
major types of solvents utilized are hydrocarbon (such
as mineral spirits and naphthas) and oxygenated (e.g.,
MEK, MIBK, ethyl acetate, and alcohols) materials. By
proper segregation, labeling, and management,
essentially all solvents can be recycled.
Information is provided on the types of solvents which
can be recycled, equipment available, and economic
factors for consideration. In addition, examples from
industry on how recycling works are provided.
Introduction
Solvents used in most industrial operations serve as
cleaning agents or reaction media. In most cases, the
solvents are not consumed, but are contaminated by
other substances. The solvents are disposed when
the contaminant level exceeds certain criteria limits.
These limits can vary widely depending upon the
particular process. For example, for engine parts
cleaning, the solvent may contain 30 to 40 percent
fuels, oils, water, and solids before it needs to be
replaced. In other cases, high purity is required and
contamination exceeding a few parts per million
signals a time to change solvents. Thus, while the
composition of used solvents can vary considerably,
the methods for reuse and recycling are applicable to
many process operations.
This chapter deals with non-halogenated solvents
used in parts and equipment cleaning and will cover
the following:
Types of solvents used.
Generation and properties of used solvents.
Options for reuse/recycling.
Waste reduction practices and examples.
Types of Solvents Used
Hydrocarbons
Hydrocarbon solvents used for parts and equipment
cleaning may be derived from petroleum, coal tar, or
natural sources. Petroleum and coal tar products
include the following:
Aliphatic naphtha such as VM&P naphtha and
mineral spirits (low and high flash).
Aromatic naphtha.
Toluene.
Xylene.
Isoparaffinic solvents.
The most common natural hydrocarbon solvent is
turpentine. Some proprietary solvents may contain
mixtures of some of the above along with lanolin (to
reduce skin irritation), detergents (for water rinsing),
colorants, perfumes, and other additives.
Paint Thinners
Paint thinners vary in composition to suit the specific
paints used. These types of solvents can contain one
or more of the following hydrocarbon or oxygenated
materials:
Petroleum or coal tar naphtha.
Isoparaffinic (odorless) solvents.
Toluene.
Xylene.
Ketones.
- MEK (Methyl ethyl ketone).
- MIBK (Methyl isobutyl ketone).
- Others.
Esters.
- Ethyl acetate.
81
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- Butyl acetate.
Alcohols.
- Methyl.
- Ethyl.
- Isopropyl.
Glycol Ethers.
- Cellosolve (butyl, etc.).
Paint thinners are included because cleaning of parts
and equipment may often precede painting and you
may wish to recycle thinners along with other
solvents.
Other Materials
For the sake of completeness, mention is made of
other organic and inorganic materials used for parts
cleaning. These are heavy-duty cleaners and paint
strippers, as noted below.
Organic Materials
These are generally mixtures of three or more of the
following solvents:
Methylene chloride.
Mineral spirits.
Toluene and/or xylene.
Ketones.
Esters.
Alcohols.
Phenol or cresols.
Glycol ethers.
Wetting agents.
Suppliers produce proprietary mixtures which may
also contain surfactants, colorants, perfumes, etc.
Since the above are mixtures, common practice is not
to recycle these materials in-house, but large volume
users could do so. The recycled product should be
reformulated; however, and thus the recycler must be
knowledgeable in this technology.
Aqueous Systems
Acid and alkaline solutions have been used for heavy-
duty cleaning for many years. Included in these
categories are organic amines, which are alkaline
ammonium type compounds. This chapter will not
cover recycling of these materiajs.
Generation and Properties of Used
Solvents
Generation Processes
Used solvents may be defined as any solvent
contaminated with other liquids and/or solids which
render it unsuitable for its intended purpose. Cleaning
solvents are generally used in operations involving
spraying, physical or vapor washing, dipping, hand
brushing, etc. The major contaminants are fuels, oil,
grease, water, dirt, metals, paint, and other
substances, depending upon the usage.
Cold Cleaning
The major nonvapor methods for cleaning parts and
equipment involve the following:
Wash Stations - in this operation, solvent
generally is circulated by pump and the part
washed continuously with a stream of liquid.
Dissolved materials accumulate in the solvent,
and solids are often removed with screens or
filters.
Spray Booth - solvent is aspirated from a
container, mixed with air, and impacts the part to
be cleaned. The sprayed solvent is collected and
recirculated. Soluble materials accumulate and
solids are removed as noted above. Organic
vapors generally are carried out the exhaust and
may or may not be collected and recycled.
Dip Tank - a large container of solvent is used for
immersion of the part in solvent. Mixers may be
added to accelerate cleaning. As above, soluble
and insoluble materials accumulate. Some solids
may settle out.
Hand/Bucket Cleaning - this is the simplest
operation, commonly used by small operators.
Brushes or rags are often used to remove tough
dirt.
In all of the above processes, the solvent continuously
degrades in quality because of accumulation of both
soluble and insoluble materials. The amounts of
various soluble and insoluble contaminants allowed to
accumulate before changing solvent are a function of
process requirements.
Vapor Degreasing
In vapor degreasing, the parts to be cleaned are
suspended above the liquid and are cleansed by warm
vapor condensing on the component. The condensed
solvent and contaminants are returned to a reservoir
where water, dirt, oils, and other contaminants are
collected. Clean vapors are continuously available to
wash the parts. Solvent is changed only when
contaminants and sludge build up enough to interfere
with vapor cleaning. Many units have separate solvent
distillation equipment as an integral part of the system.
Properties of Used Solvents
Typical properties of used and virgin (or recycled)
hydrocarbon solvent (mineral spirits) are given in
Table 10-1. This example would be typical of usage
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Table 10-1. Properties of Used and Recycled
Test Test method
Flash point, TCC, °F ASTM-D-56
Distillation, °F ASTM-D-86
IBP
10%
20%
30%
40%
50%
60%
70%
80%
90%
FBP
Residue
Chlorine content
Water, oil & sediment,
% ASTM-D-95
Appearance Visual
Mineral Spirits
Used solvent
< 100-1 20
150-330
150-340
170-340
300-345
320-350
325-350
330-370
340-390
350-400
400-600
Above 500
30 % Vol (max)
<0.1
2-20
Brown/black
Reclaimed solvent
102-110
315-330
320-340
325-350
330-365
350-400
2-5 %Vol
<0.1
<0.1
Clear/white
for cleaning gasoline engine parts. The major
contaminants are as indicated below.
Gasoline - this is indicated by the low flash point
and low boiling (less than 320° F) components.
The used solvent may contain 10 to 12 percent
gasoline.
Water - water can be detected by various means.
In the example given, it might show up as a
separate fraction during the distillation. It would
also be detected in the Water, Oil, and Sediment
Test.
Oil and Sediment - dissolved lube and other oils
would be detected in this test as well as sediment.
By proper distillation, the contaminants can be
removed and the reclaimed solvent will meet new
or virgin product specifications.
Other pure organic materials which might be used as
cleaners, such as MEK, ethyl acetate, and others,
might have similar contaminants, and can be
reclaimed to original specifications.
Paint thinners are a special case. Since thinners are
blended products and formulated to meet specific
volatility and solubility requirements, their reclamation
for use as paint thinners generally is not
recommended. However, used paint thinners are
generated mainly from cleaning of brushes, spray
guns, and other application equipment. For these
purposes, product specifications are not usually of
significance.
Thus, used paint thinners can be reclaimed readily by
gravity settling, filtering, distillation, or other means.
Reclaimed paint thinner is usually satisfactory for
cleaning equipment, but is not recommended for
thinning paints.
Options for Reuse and Recycling
Consideration of options for reuse and recycling of
solvents should include segregation practices,
substitutes and downgrading, equipment
requirements, costs, and environmental regulations.
These concerns are discussed below.
Increasing Reuse and Recyclability
Segregation
Segregation of solvents is one of the most important
management practices affecting reuse and
recyclability. Past practices often have neglected
segregation and changes sometimes are difficult to
implement. What to segregate depends upon which
downstream operations will be used. Generally,
solvents need to * be segregated strictly by each
individual type. Mixing solvents often makes in-house
recycling impossible. Proper labeling and/or color
coding and adequate containers for collection of used
solvents enhances segregation.
83
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Substitutes
Replacement of one solvent for another is often easier
said than done, but it needs to be considered and can
lead to easier recycling. Several examples follow.
If chlorinated solvents are used for cleaning electrical
parts and hydrocarbon solvents for machine parts,
using hydrocarbon solvent for both may simplify
recycling. While hydrocarbons often are used for both,
some users may prefer not to use these solvents
because they evaporate more slowly and are
flammable.
Ethyl acetate is sometimes used for cleaning
purposes. Replacement with a hydrocarbon solvent
often can provide similar results and simplifies
reclamation.
Proprietary hydrocarbon solvents often contain
emulsifiers, lanolin, colorants, odorants, etc., which
may or may not be essential to the cleaning process.
Recycling this type of mixture reclaims only the
hydrocarbon fraction. Thus, the recovered material is
not the same as the proprietary solvent. Reformulation
of the solvent can be done by a knowledgeable
person, if desired.
Emulsifiers
Emulsifiers are used to aid in solvent penetration of
water-wet oil, grease, or dirt. The emulsifiers also
enable the solvent to be washed off with water. If
these properties are not essential, emulsifiers are not
needed.
Lanolin
Lanolin is added to provide residual oil, thus reducing
skin irritation and dryness caused by contact with the
solvent. This ingredient is not essential to the cleaning
process and solvent users should wear gloves or use
a hand cream after contact.
Colorants and Odorants
Colorants, odorants and some other ingredients are
added for product identification and customer
acceptance. While these factors can be of some
importance, they are not essential for cleaning
purposes.
Aqueous Emulsion Systems
Aqueous emulsion systems have, been offered as
substitutes for cleaning solvents and are claimed to be
effective for cleaning engine and electrical parts.
These systems may be satisfactory for a number of
applications. However, there are two major concerns.
One is that water-based systems may require drying
to eliminate residues. A second problem is disposal of
the dirty water. If significant quantities of oil, grease,
or other organic materials are carried off in the water,
some treatment may be required prior to discharge.
Downgrading
In-plant reuse by downgrading is a common practice
where a number of cleaning operations are
conducted. Following are two examples:
Cleaning of bearings often requires use of high
purity, virgin solvent. Since these bearings are
relatively clean to start with, the used solvent from
this operation can readily be downgraded for use
in cleaning dirtier engine components.
Calibrating fluid used for fuel system components
is often a special grade of mineral spirits. After
initial usage, this material can be downgraded for
other solvent purposes.
Economics
The economics of solvent recycling is dependent
upon the following costs:
* Solvent.
Percent of recoverable solvent.
Collection and segregation.
Equipment and installation.
Operations.
Quality assurance/quality control.
Disposal.
A generalized cost estimate for solvent recovery and
payback of equipment costs is given in Figure 10-1 for
solvents costing from $1 to $11/gallon. As observed,
both solvent costs and volume have a significant
impact on payback periods. More detailed cost studies
are needed for specific cost/benefit analysis.
Processes and Equipment Used
A number of processes utilize equipment for
separating and recycling used solvents. Most
operations for in-plant use are simple, but a wide
range of options are available, where appropriate.
These methods are discussed briefly in this section
and another paper covers this subject in greater
detail.
Gravity Separation
Simple settling of solids and water is often practiced
for reuse of solvents. Paint thinners may be reused
many times if solids are allowed to settle. The
supernatant liquid can be removed for cleaning
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Figure 10-1. Plots of solvent volumes vs. payback period (years) for solvents of different costs.
Plots of Solvent Volumes vs Payback Period Years
for Solvents ofDifferent Costs
$1/gal (i.e.. Heptane)
$1.5/gal(i.e., P-D-680)
$2/gal (Non-halogenated)
$3/gal (Halogenated)
$4/gal (i.e., MeCI, TCE, TCA)
$11/gal (Freon 113) - Equipment
costs higher than for above
456
Years to Payoff Investment
purposes. Centrifuges are also used to accelerate
gravity separation.
Batch Stills
This type of equipment may be described as a flash,
pot, or single-plate batch still. The used solvent is
heated, vaporized, and the vapors condensed into a
separate vessel. Solids of high-boiling liquids remain
in the pot or distillation vessel as a residue. Liquids
boiling up to about 400 °F can be recovered. If mixed
liquids are used they will not be separated unless the
final boiling point of one solvent is about 50 to 60° F
below the initial boiling point of the other solvent.
Batch stills are supplied by numerous vendors. Major
design variations include the following:
Size - from 5 to 500 gallon capacity
Heating
- Electrical
- Steam jacket
- Direct steam injection
- Heat transfer fluids
With or without vacuum attachment
Materials of construction
Clean out
- Bottom
- Side
- Top
- Lift-out trays
- Plastic bag liners
Controls
Costs range from $2,000 to $3,000 for 5-gallon units
to well over $100,000 for the largest stills. These units
are capable of reclaiming solvents to purity standards
meeting or exceeding new product specifications.
Fractionation Units
For separation of solvent mixtures, fractionation units
may be required. These are generally custom-made
and can be provided to meet almost any separation
requirement. Size, efficiency, and design can be
varied to suit the user's needs. Costs generally range
from $30,000 and up.
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Thin-Film Evaporators
This type of unit is a variation of flash stills in which a
thin film of the used material is deposited on a
rotating, hot metal surface. The solvent is flashed off,
vaporized, and either condensed or passed on to a
fractionating unit for separation of specific solvents.
These units are very versatile and specially suited for
viscous liquids. Costs range from about $30,000 and
up.
Vapor Degreasers With/Without Recycle
For continuous cleaning operations, and those
desiring excellent solvent penetration, vapor
degreasers are often preferred. Only the vapors
contact the parts and condensate is returned to a
sump. Some designs have condensers around the
sides of the vessel and others at the top. Fresh, clean
solvent is continuously vaporized to clean parts. In
systems without internal recycle the solvent can
become contaminated with components that vaporize
with the solvent to reduce cleaning effectiveness. To
avoid this, the dirty solvent may be recycled in a
separate unit where the contaminants are removed.
Generally, vapor degreasers are fairly large units
containing from about 50 to several hundred gallons of
solvent. Costs are also proportionately large, ranging
from $100,000 and upwards.
Toll Recyclers
A variation of in-plant recycling can be accomplished
by toll recyclers. While the solvent is not recycled on-
site, the solvent is replaced on-site. Solvent wash
stations are often serviced by companies in this
business. Service charges may vary from 50 to 90
percent of new solvent costs.
Hazardous Waste Reduction Practices
and Examples
Audit
Any waste reduction program should start with an
audit. This can be a do-it-yourself activity or larger
facilities may wish to hire an outside consultant. The
basic components of a waste audit are outlined in
Table 10-2 and a format for actual use is given in
Table 10-3. Audits should be conducted by personnel
familiar with the solvents used; process operations;
and handling, treatment, and disposal options.
Illustrative examples include:
At a large shop, a decision was made to use a
proprietary solvent when a less expensive
nonproprietary solvent would have saved money
and been easier to recycle.
A salesman recommended replacement of a
chlorinated solvent by an odorless paint thinner for
engine parts cleaning. The user did not realize
that common mineral spirits would have done a
better job and cost about 50 percent less.
Table 10-2. Waste Audit Outline
Sfep 1 - Collect Information
Tabulate existing data
Mass balance assessment
Check completeness of data
Sfep 2 - Evaluate Waste Handling
Raw materials
Housekeeping
Costs
Sources
Practices of personnel involved
Sfep 3 - Management Alternatives
Approach for each waste
Employee requirements and training
Housekeeping improvements
Segregation of waste
Capital investments
Reformulation
Reuse
Technical, economic, and liability assessments
Sfep 4 - Review and Update
Assess progress
Track and assess changes in
- Raw materials
- Processes
- Products
- Technology
- Regulations
Table 10-3. Standard Waste Audit Format - Automotive
Repairs
Name and location of shop or business
Name of audit personnel
Date of audit
Type of shop
- Automotive repair
- New car dealer
- Diesel repair
- Transmission repair
- Brake/muffler shop
- Radiator service
- Alignment
- Suspension/chassis
- Scheduled maintenance
- Quick lube changes
- Body/painting
Size of shop
- Vehicles serviced per week
- Number of service bays available
Services provided
Number of employees
Raw materials used
Raw material storage (complete for each item)
- Raw material (brand name/common name)
- Item number
- Volume in inventory
- Describe usage
- Describe disposal practice
- Describe storage facilities
(i.e.) 55-gal drum (Continued)
86
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Table 10-3. (Continued)
Containers (volume)
Above or underground tank,
Covered/open
Indoor/outdoor
Secured
- Delivery system
(i.e.) Gravity
Funnel
Pump
- Material control practices
(i.e.) Stockroom attendant
Access (limited/unlimited)
Signout sheet
Material usage (describe for each type)
- Sink (size/description/location)
- Dip tank (size/description/location) ,
- Jet spray (size/description/location)
- Spray hood (size/description/location)
Waste material management
- Segregation practiced (if yes, describe)
- If no segregation, describe practice
- Options available for segregation
- Storage facilities (describe)
- Disposal practices
- (i.e.) On-site recycling
- Serviced by equipment leasee/maintenance contractor
- Picked up by contractor
- Disposed in municipal solid waste
- Disposed to municipal sewer
- Disposal costs
(i.e.) Oils
Solvents
Residues/sludges
Anti-freeze
Aqueous materials
Other
Material losses
Provide a schematic for waste management practices
Prioritized sites of significant waste generation
Waste management options
Source reduction options
- Material substitutions
- Process changes
- Housekeeping
Regulatory compliance evaluation and needs
Recommendations for improved management
Selection of the Best Option
After completion of an environmental audit and
consideration of viable options, economics, and
applicable regulations, selection of the best option
should be relatively easy. The major management
practices which need to be selected are discussed
below.
Segregation
Uncontrolled mixing of used solvents yields waste
slops with little or no economic value and little chance
of recycling. In addition, because waste mixtures are
often designated as hazardous wastes, their disposal
is becoming more costly. A summary of
recommended options for a number of solvents is
given in Table 10-4. Segregation by each individual
solvent is generally the best means of optimizing
recovery and minimizing costs. Alternate options are
usually less desirable and not as cost effective.
Example
We have all seen or heard of locations with vast
numbers of drums of mixed solvents and other
materials. These were accumulated because plant
operators were not concerned about disposal or were
not willing to pay disposal costs. My experience has
been that many plant managers believed these drums
contained valuable materials which should have been
marketable, but realistically, were not.
Many Superfund sites were created because of
improper management and disposal. With a minimum
of segregation, many of these waste drum fields could
have been disposed to cement kiln operators that had
capabilities for burning a variety of mixtures.
Collection
Adequately marked containers must be provided to
encourage and ensure proper collection and
segregation. Good practice includes color coding,
visible and legible labels, and a manifest system.
Color coding can simplify identification and is easy to
implement. Labels can be hung on walls, placed on
top of a container, or stenciled on collection drums.
Labels stenciled on both sides of a container work
well; those only on top can be obliterated by a spill. A
manifest should be used even for internal recycling.
The generator should fill out a manifest form, attach it
to the container, and have a copy sent to the recipient
and to a central control person.
Recycling
Recycling or reclamation of used solvents, can be
accomplished with in-house equipment and facilities
for almost all pure solvents, but is generally not
practical for some mixed solvents. This discussion
covers solvents segregated and collected after use as
well as solvents recovered in vapor recovery units.
Recyclable and Nonrecyclable Solvents
Solvents which can be recycled readily are listed in
Table 10-4. These materials can generally be recycled
to meet original solvent specifications.
In addition to those noted above, paint thinners can
also be recycled. Since most thinners are mixtures
and lose volatile solvents in use, the recycled solvent
is not the same as virgin material. Thus, reclaimed
thinner should not be used as a paint thinner, but can
be used to clean paint equipment.
Typical nonrecyclable solvents are noted below, along
with brief comments.
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Table 10-4. Summary of Segregation Recommendations for Reclamation and Disposal of Solvents
Solvent Segregation Guidelines
Preferred Option
Alternate Options
Hydrocarbons Group A
Calibrating Fluid
Coal Tar Naphtha
Dry Cleaning Solvent
-100SF Min. Flash Point
-140°F Min. Flash Point
Naphtha, Aromatic
Segregate and reclaim for original use
Mix and reclaim as a general cleaner or wash solvent.
Can mix with chlorinated and oxygenated solvents for
disposal to selected cement kiln operators.
Hydrocarbons Group B
Thinner, Paint
Xytene
Agitene
Naphtha, Aliphatic
Toluene
Halogenated
Methylene Chloride
Tetrachtoroethane
1,1,1 -Trichloroethane
1,1,2-Trichloro-
1,1,2 tritluoroethane
Oxygenated
Acetone
Ethyl Acetate
Ethyl Alcohol
Isopropyl Alcohol
Methyl Alcohol
Methyl Ethyl Ketone
Methyl Isobutyl Ketone
Segregate and reclaim for original use
Segregate and reclaim for original use
Segregate and reclaim for original use
DO NOT MIX WITH GROUP A
Can mix with chlorinated and oxygenated solvents for
disposal to selected cement kiln operators.
Mix and reclaim as a general cleaner or wash solvent.
All chlorinated, hydrocarbon and oxygenated solvents can be
mixed and disposed to selected cement kiln operators
Can mix with all chlorinated and hydrocarbon solvents for
disposal to selected cement kiln operators.
Carbon Removers and Paint Strippers.These mixtures
are generally quite toxic since many contain phenolic
compounds and thus in-house recycling is not
recommended.
Proprietary Solvents. Many proprietary cleaning
solvents contain additives (as noted above) which are
not recovered in distillation. Therefore, the recycled
material is not the same as the original solvent,
The major processes and equipment used are
discussed briefly below:
Gravity Separation. Gravity separation is used
mainly for paint thinners.
Batch Stills. Many companies manufacture, sell
and service batch stills for in-house recycling of
solvents. A list of the major suppliers is given in
Table 10-5 along with some general data on the
types, ranges, feature's, and costs of this
equipment.
These units will not separate solvents and must
be used for only one solvent at a time. They can
be used for a variety of solvents with cleaning
between batches.
Examples
Navy
At the Naval Shipyard in Portsmouth, VA, a 15-
gal/day batch still has been successfully used to
recover mineral spirits and paint thinners. Savings
amount to about $15,000 per year and the
equipment was paid off in less than six months*.
Air Force
Bobbins AFB has a number of different units for
recycling over 50,000 gallons per year of various
solvents. Total savings are reported to be over
$600,000 per year.
Industries
Many industries have successfully recovered
solvents with in-house units, thereby saving
This information was obtained from an article dated 11/5/85 that
appeared in. the Virginia Pilot (a local Portsmouth, .VA, newspaper).
88
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Table 10-5. Suppliers of Solvent Recycling Equipment Suitable for On-Site Reclamation - Single-Plate Packaged Stills
I Supplier
Alternative Resource Management
7134S. Yate (Suite 400)
Tulsa, OK 741 36
918-495-0535
Baron Blakeslee
2001 N. Janice Ave.
MelrosePark, IL60160
312-450-3900
Branson Cleaning Equip. Corp.
P.O. Box 768
Shelton, CT 06484
203-796-0400
BR Instrument Corp.
P.O. Box 7
Pasadena, MD 21122
301-647-2894
DC I International
1229 Country Club Rd.
Indianapolis, IN 46234
317-271-4001
Detrex Chemical Ind. Inc.
P.O. Box 501
Detroit, Ml 48232
313-358-5800
Disti Inc.
131 Prince St.
New York, NY 100 12
212-505-0611
Finnish Eng. Co. (Extratec)
921 Greengarden Rd.
Erie, PA 16501-1591
814-455-4478
Finishing Equip. Inc.
3640 Kenneber Dr.
St. Paul, MN 55722
612-452-1860
Giant Distillation & Recovery Co.
3156 BellevueRd.
Toledo, OH 43606
Hoyt Corp.
Forge Rd.
Westport, MA 02990
617-636-8811
Lenape Equipment Co.
P.O. Box 285
Manasquan, NJ 08736
201-681-2442
National Ultrasonic
Chicago, IL 60626
312-465-6780
Throughput1
(gal/hr)
1.5-100
10-120
12-60
1-2
250
30-180
2-70
15-380
No
Available
Data
1.5-10
4-8
4-45-
No
Available
Data
Solvent
Capacity
(gals)
5-100
8-95
10-60
3-6
250
50-200
10-50
5-50
No
Available
Data
5-60
25-50
5-30
No
Available
Data
Heating
Options
Electric/
Steam
Electric/
Steam
Electric/
Steam
Electric
Dir.
Steam
Injection
Electric/
Steam
Steam/
Hot Oil
Electric/
Steam
Electric/
Steam
Electric/
Oil
Oil
Electric
No
Available
Data
89
Cooling
Options
Refrig/
Water
Refrig/
Water
Refrig/
Water
Water
Water
Water
Water
Water
Water
Water
Water
Refrig/
Water
No
Available
Data
Explosion
Proof
Yes
No
No
Yes
Yes
No
Yes
Yes
No
Yes
No
No
No
Available
Data
Cost $K
2.5-
100 +
5-8
4-10
9-12
No
Available
Data
5-10
8-54
5-80
No
Available
Data
5-100
No
Available
Data
3-20
No
Available
Data
Solvent
Types
Designed
for
All
Halogen-
ated
Halogen-
ated
All
All
Halogen-
ated
All
All
Halogen-
ated
All
Halogen-
ated
Halogen-
ated
Halogen-
ated
Comments
Atmospheric
& Vacuum
Models
Available
For Lab
Operations
For Removal
of Solvents
from Oils
Make a Wide
Range of
ATM. &
VAC. Models
Atmospheric
& Vacuum
Models
Available
Also Make
Vapor
Recovery
Units
(Continued)
-------
Table 10-5. (Continued)
Supplier
Solvent
Solvent Explo- Types
Throughput1 Capacity Heating Cooling sion Designed
(gal/hr) (gals) Options Options Proof Cost $K for Comments
Phillips Mfg. Co.
7334 No. Clark St
Chicago, IL 60626
312-338-6200
Progressive Recovery Inc.
1976 Congressional Dr.
SI. Louis. MO 63146
314-567-7963
Ramco Equipment
32 Montgomery St.
Hillside, NJ 07205
201-687-6700
Rocyclene
1910 Trade Zone Blvd.
San Jose, CA95131
408-945-8600
Vaco Sdv Co.
P.O. BOX 26147
Cincinnati, OH 45226
513-321-9178
Westinghouse Electric Co.
Box 300
Sytesvilte, MD 21784
301-795-2800
5-125 15-125 Electric/ Water No
Steam
7-15 Halogen-
ated
5-35 5-25 Hot Oil Water Yes 8-30 All
25-200 30-135 Electric/ Water No 7-20
Steam
2-20 15-35 Electric/ Water Yes 4-21
Heated
Oil
1.6-10 5-60 Electric Air Yes 10-3
Halogen-
ated
All
Also Make
Custom
Designs
All No Cooling
Needed
15-30 18-50 Electric Refrig/ No 7-10 Halogen-
Water ated
For the lowest volatility solvent.
valuable resources, and eliminating or drastically
reducing disposal requirements.
Fractionation Units. Custom-made fractionation
units can be obtained from companies such as
those noted in Figure 10-6.
Thin-Film Evaporators. To recover solvents from
high viscosity fluids, thin film evaporators or wiped
surface evaporators are generally recommended.
In some cases, these units may be followed by
fractional distillation units for better separation of
solvents. Suppliers of this equipment are noted in
Figure 10-7.
Example
Navy
The Navy has been recovering Freon 113 at the
Naval Shipyard in Portsmouth, VA, for many years
and saving $20,000 to 30,000 per year.
Vapor Degreasers with and without Recycle.
Vapor degreasers are usually large units which
generally have a freeboard area for condensing
vapors above the vapor cleaning section. Some
units contain internal solvent recycle systems,.
thereby minimizing the need for cleanout. Most
vapor degreasers utilize halogenated solvents.
Disposal
Disposal of sludge bottoms from most distillation units
is still necessary. Experience has shown that for
solvents used in precision cleaning, only a small
volume of fine solids is obtained. These solids can
often be disposed as a non-hazardous solid waste. At
the other extreme are sludges from paint thinners.
These residues can be taken to dryness and disposed
as a hazardous waste.
Interesting exceptions are still bottoms from mineral
spirits used for engine cleaning. The residues are
mainly oils and can often be blended with waste oils
for disposal.
In almost all cases where solvents are recycled, some
residues remain which have to be disposed as
hazardous wastes. Options include land filling,
incineration, encapsulation, blending with asphalt, and
others.
Conclusions
ln-plant recycle and reuse of solvents can be
achieved for most solvents. The major concerns are:
90
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Table 10-6. Suppliers of Solvent Recycling Equipment Suitable for On-Site Reclamation -
Custom Builders of Fractional Distillation Units
Type of Equipment Available
Throughput1 Solvent Capacity
Supplier (gal/hr) (gals)
Advanced Process Systems ' 5-100 5-100
1 0400 Linn Station Rd., Suite 31 0
Louisville, KY 40223
Artisan Ind. Inc. 10-50 10-50
73 Pond Rd.
Waltham, MA 02154 617-893-6800
Chem-Pro Equip. Co. 5-50 10-50
27 Daniel Rd.
Fairfield, NJ 07006 201-575-1924
Distillation Eng. Co. 5-50 10-50
1 05 Dorsa Ave.
Livingston, NJ 07039 201-992-9620
Ferguson Ind. Inc. N/A2 N/A
1 900 W. Northwest Hwy.
Dallas, TX 75220 214-556-0010
Finish Eng. Co. 5-50 10-50
921 Greengardens Blvd.
Erie, PA 16501 814-455-4478
Progressive Recovery Inc. 3-30 10-50
1 976 Congressional Dr.
St Louis, MO 63146 314-567-7963
Explosion
Proof Price $K
Yes 20-50 +
Yes 20-30 +
Yes 20-30 +
Yes 20-30 +
Yes 20-30 +
Yes 20-30 +
Yes 20-40 -t-
' For the lowest volatility solvent.
2 N/A = No data available.
Table 10-7. Suppliers of Solvent Recycling Equipment Suitable for On-Site Reclamation - Thin-Film Evaporation
Supplier
Throughpuf Solvent Capacity
(gal/hr) (gals) Heating Options
Price Range
Cooling Options $K
Alpha Laval Inc.
2115 Lin wood Ave.
Ft. Lee, NJ 07024
201-592-7800
Artisan Ind. Inc.
73 Pond Rd.
Waltham, MA 02154
617-893-6800
Brighton Crop.
11861 Mosteller Rd.
Cincinnati, OH 45241
513-771-2300
Luwa Crop.
P.O. Box 16348
Charlotte, NC28216
704-394-8341
Progressive Recov. ,lnc.
1976 Congressional Dr.
St. Louis, MO 63146
314-567-7963
5-50
5-50
7.5-200 5-200
50-1200 Cont.
15-300 15-300
Hot oil
Steam/Oil
Steam/Hot oil
Steam/Hot oil
Steam/Hot oil
Refrig/Water 50 +
Refrig/Water 50-130 +
Water
Water
Water
18-43
25-50 +
40-120
"For the lowest volatility solvent
91
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Quality and quantity of used solvents.
Segregation and handling practices.
Selection of recycling equipment.
Management practices.
Costs for operation and maintenance.
After completion of an environmental audit and review
of the above, experience has shown that in-house
recycling is often the most cost-effective and
environmentally-preferred option.
92
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Chapter 11
Commercial (Off-Site) Solvent Reclamation
Brian R. Dawson
Solvent Resource Recovery, Inc.
West Carrollton, OH 45449
Introduction
Solvents are an important part of most industrial
operations. Almost all plants use solvents, usually for
cleaning, degreasing, painting, paint stripping, or
extraction purposes. Therefore, proper management
of solvent wastes is of widespread concern. There are
several disposal methods available to solvent users,
but in many cases the most environmentally sound
and economical choice is not to dispose of the solvent
at all, but to recycle it.
If we briefly review the generally accepted priority list
of hazardous waste management, we see that first, it
is' incumbent upon generators of waste to institute a
program to reduce the amount of waste generated.
Second, after the amount of waste generated has
been minimized, recycling is considered the next most
appropriate alternative. Third on most lists is
incineration, and fourth is chemical or biological
treatment to render the waste nonhazardous. Landfills,
deep-well injection, and other methods fall further
down the list.
Recycling is ranked very high on the priority list of
alternatives for hazardous waste management. This is
because it accomplishes two very important
objectives: one, it further minimizes the quantity of
waste to be handled; and two, it conserves precious
natural resources. Waste minimization is
accomplished because the reclaimed solvent
becomes a usable product, no longer a waste. Natural
resource conservation is accomplished because the
petrochemical building blocks necessary for virgin
manufacture are not required, and the utility
requirements (such as electricity and steam) to
reclaim are a fraction of the requirement for virgin
manufacture.
There are many types of solvents that are commonly
recycled. Most prevalent are paint solvents. Almost
any industrial process involves painting, and requires
solvent for application, cleaning of paint masks, spray
equipment, and line flushing. Even the manufacture of
paint requires solvents for cleaning of mixing
equipment and transfer lines. The solvents generally
used for these purposes are various mixtures of
ketones (such as acetone, methyl ethyl ketone, and
methyl isobutyl ketone), esters (such as ethyl acetate,
n-butyl acetate, and isopropyl acetate), alcohols (such
as ethanol, isopropanol, and n-butanol), and aromatic
hydrocarbons (such as toluene and xylene).
In the metal working industry, lubricating oils, cutting
oils, and greases are used in the processes, and must
be removed prior to further work, such as plating or
painting. The solvents used for this type of cleaning
include chlorinated hydrocarbons and petroleum
distillates such as various mineral spirits* toluene, and
xylene.
In the printing industry, solvents are used as ink
additives, and also for cleaning of rollers and presses.
Commonly used are alcohols, esters, and aromatic
hydrocarbons, as well as various mixtures thereof.
The electronics industry uses many solvents for
cleaning, stripping, defluxing, and even as a photo-
resist developer for printed circuit boards. Chlorinated
and fluorinated hydrocarbons are generally used.
There are also thousands of small commercial
establishments, such as auto repair garages, auto
body shops, and dry cleaners using solvents such as
petroleum hydrocarbons, paint thinners, and
perchloroethylene.
Virtually all solvent-use applications are physical in
nature, not chemical. In other words, the chemical
structure of the solvent is not altered. It is merely
contaminated, so the purpose of solvent reclamation
is to remove the impurities, making the solvent
available for reuse. The reclamation process also
does not chemically alter the solvents, therefore, there
is no limit to the number of times a solvent may be
recycled or reused.
On-site reclamation, where practical, is generally
preferred to off-site reclamation to avoid the risk and
liability of transportation. If on-site reclamation is not
93
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practical because of economic or quality limitations,
off-site reclamation should be considered as the next
alternative.
Types of Recycling
Two basic types of off-site or commercial solvent
recycling are available: custom toll recycling and open
market recycling. In custom toll recycling, the
generator's spent solvents are kept segregated, batch
processed separately to the generator's specification,
and then returned for reuse. While the requirements
vary among different processes, the minimum batch
size is generally 1,000 to 2,000 gal, so this option
usually is limited to larger generators of waste.
The batch size limitations are caused by processing
equipment size, economies of scale, and sometimes
transportation costs. The processing equipment is
engineered to handle large volumes of waste, and
small batches will not "wet" the system, causing a
very low percentage of recovery. If the distillation
system is designed to circulate 500 gal through the
heat exchanger, a 1,000-gal batch of waste processed
can yield a maximum of 50 percent recovery.
However, a 2,000-gal batch can yield 75 percent
recovery, a 3,000 gal batch can yield 83 percent
recovery, a 4,000-gal batch can yield 80 percent, and
so on.
Economies of scale realized from larger batch sizes
come from the charge or fill time, heat up time, still
bottoms pumping time, and cleanout time. Each of
these steps is necessary for all batches, and requires
approximately the same amount of time whether
processing 1,000 gal or 4,000 gal.
Transportation costs are often identical, whether
shipping full truckloads or partial truckloads, so the
larger quantity' shipped translates to a lower cost per
gallon.
If the above limitations can be overcome, significant
benefits can be realized. The generator can be
assured that the reclaimed solvent returned is not
contaminated with any solvent foreign to his system,
since the waste is kept segregated through all
processing steps, thereby simplifying quality
assurance and quality control. The generator is also
dealing with a known entity, i.e., the solvent returned
is coming from solvent waste already used in his
operations. This can simplify SARA Title III and
Worker Right-to-Know concerns.'
Economics of custom toll recycling are governed by
four key factors. The first is processing costs.
Processing costs not only entail the usual items such
as labor, utilities, and equipment investment, but also
the administrative costs associated with maintaining
environmental compliance. Processing costs are also
affected by specifications required. The narrower or
tighter the specification for the reclaimed solvent, the
higher the cost, especially if drying is required.
Second is the disposal cost of the still bottom
residues, or otherwise unrecovered portions of the
waste stream. Third is transportation cost. Last,
though probably most important, is the percent
recovery, or yield. The higher the yield the lower the
unit processing cost, disposal cost, and unit
transportation cost.
Generally, after all costs are considered, the
reclaimed solvent is returned to the generator at a
price similar to or slightly lower than virgin solvent
purchase. While this may not seem to be very
motivating, we must not forget to consider the
alternative - if the spent solvent is not recycled, it
must be disposed, and disposal costs are very high
these days. Therefore, recycling avoids the disposal
alternative, and makes the natural resource available
for reuse.
The second form of commercial reclamation is known
as open market recycling, where the spent solvents
are co-mingled with like or similar wastes from many
generators, and processed to specification for resale
and reuse in the marketplace as refined solvent. This
option is available to virtually all generators of spent
solvents, so long as the recycling facility offers the
service (some companies specialize in only custom
toll recycling), and there is a resale market for the
refined product. One other potential limitation involves
waste segregation - if a generator is using several
different solvents in different parts of his operation,
and co-mingles the.waste, there is a strong likelihood
that the refined solvent from the waste may not be
suitable for resale, leaving disposal as the only
alternative.
Though there are exceptions, most solvent waste
streams are suitable for recovery. Since the recycler
will be deriving revenue from the resale of the
product, the benefit to the generator can be a lower
disposal cost. Also, the generator can be assured that
his waste is being managed in an environmentally
acceptable manner, with the corresponding benefit of
natural resource conservation.
The charges assessed for the management of spent
solvents through open market recycling vary with the
relative resale value of the refined solvent. The
general rule of thumb in the industry is that refined
solvents selling for less than $0.20 per pound are
marketed at 80 percent of virgin price, and those
selling for more then $0.20 per pound are marketed at
90 percent of virgin price. Since the costs associated
with recycling have no relationship to market price, a
recycler must assess disposal charges to make a
profit on low-priced reclaimed solvent. While the
charges will vary depending on quantity and
transportation, the disposal price is in the range of
94
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$50 to $100 per drum for most nonchlorinated
solvents.
Most chlorinated solvents have a higher resale value,
and under certain circumstances, some generators
are even paid for their chlorinated waste. More
frequently, though, the charges range from zero to
$50 per drum.
The three key factors affecting the disposal cost
(other than chlorinated vs. nonchlorinated) are
quantity, transportation, and character of the
impurities. It takes exactly the same amount of time to
process the paperwork and perform the analyses for
one drum as for 40, so the more drums
shipped/received, the lower the unit processing cost.
Transportation costs are affected in a similar manner.
The key factor, though, is the character of the
impurities. If water is present in the waste, it too
becomes a waste that must be properly managed at
high cost. Solid or nonpumpable impurities are not
recoverable, and must be properly disposed at high
cost. Last, foreign objects, such as rags, gloves, nuts,
bolts, filter cartridges, pop cans, paper cups, etc.
present in the waste must be separated and properly
disposed as waste, usually by incineration. When
waste minimization techniques are being considered,
care should be taken to avoid these impurities, as
they add significantly to the processing cost of solvent
waste.
Reclamation Technology
Technologies exist today to assure high quality
reusable solvent. The prevailing method of processing
is distillation or vaporization. All recyclers use the
same basic systems and technology, but they apply
those systems in a highly individualized manner.
Many solvents can be processed into a reusable state
by simple vaporization. This is usually done in a pot
still or thin-film evaporator.
In the pot still, the spent solvent is charged to the
system, then heated to boiling by steam or hot oil heat
exchangers. The heat exchangers can be either
internal or external. Once boiling, the solvent vapors
exit the system to a water-cooled heat exchanger, and
are then cooled to a clean solvent liquid. The
nonvolatile residues, or still bottoms, are then pumped
to storage awaiting final disposal. With strict land
disposal regulations in effect, the usual, most cost-
efficient disposal method is through a waste derived
fuel program. This is accomplished by blending the
still bottoms to a prearranged specification for
consumption as a fuel in a cement or lightweight
aggregate kiln. This disposal method has the
advantage of assuring destruction ratio efficiencies
comparable to those of an incinerator, but at
significantly lower cost. Also, there is sufficient
capacity available in the market for this disposal, while
commercial incineration capacity is limited.
Similar to pot stills in reclamation technology are thin-
film or wipe-film evaporators. The difference is that in
a pot still the spent solvents are cooked, while in the
thin-film evaporator the waste is pumped into the top
of the unit, where it is then spread in a thin layer on
the internal surface by rotating wiper blades. The
internal surface is heated by a steam or hot oil jacket.
By exposing the solvent waste to this heat in a thin
layer, the organic solvents are flash evaporated, once
again to a heat exchanger, to be condensed as clean
solvent liquid. In these systems, the nonvolatile
residues continuously exit the bottom of the
evaporator, to be handled in the same manner as pot
still bottoms. The advantage of the thin-film evaporator
over the pot still is that the batch size is not limited by
the size of the pot, since the system is fed from an
external storage tank, and operated continuously.
Also, some nonvolatile residues are subject to
chemical breakdown when cooked, which can cause
odor or color problems in the reclaimed solvent. If
thermal breakdown is not a concern, the pot still has
the advantage of giving higher recovery yields.
Both pot still and thin-film evaporators are often
operated under vacuum, to reduce the boiling point of
the solvent, thus reducing the amount of energy
required, and also enabling the recovery of some high
boiling solvents.
The disadvantage of both these systems is that they
have no separation capability, other than volatile
organics from nonvolatile organics. In other words, all
the volatile organic solvents entering the systems will
exit as product. So long as the solvent waste has
been kept properly segregated, and the recoverable
solvent portion is pure, this is acceptable. But if
volatile organic impurities are present in the waste,
they will be present in the reclaimed solvent. This may
cause quality problems; to address the situation, some
recyclers have installed fractionating columns.
Fractional distillation is an extremely complex
technology, with several different types of columns
and a vast variety of sizes and configurations. The
most common types of columns are packed columns
(usually the porcelain saddles), bubble cap columns,
sieve plate columns, and valve tray columns. The
taller the column design, the more trays, enabling
more separation or clarification capability. As the
diameter of the columns increases, more throughput
capacity is obtained.
The underlying principle of operation of all fractioning
columns is the same. The volatile organics are heated
by steam or hot oil by means of internal or external
heat exchangers. As the solvent wastes reach the
boiling point, the vapors enter the column. The lower
boiling components migrate to the top of the column,
95
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with the column design promoting internal
condensation of higher boiling components, with
subsequent migration to the lower part of the column.
As the lower boiling vapors exit the top of the column,
they are condensed to a liquid. During the initial start
up operations of a batch run, all the condensed liquid
(clean solvent) is pumped back into the top of the
column as reflux, further promoting internal
condensation and migration. When equilibrium is
reached in the system, part of the reflux condensate
is pumped to product storage, 'with the remainder
continuing back to the column. The amount returned
to the column compared with the amount pumped as
product is known as the reflux ratio.
When separating solvents with a narrow spread
between their boiling points, the reflux ratio may be
very high - as much as 5:1. This means that for every
6 gal boiled out of the system, 5 gal go back, with 1
gal of product produced.
The reflux system enables a high purity portion of the
lower boiling solvent to be reclaimed. As the lowest
boiling component is removed to clean product
storage, the next highest boiling component will
migrate to the top of the column. No fractional
distillation is 100 percent efficient, so there will be a
small intermediate cut of the mixture of the two
components, taken to separate storage. This may be
fed back to subsequent batches.
After the intermediate cut, the next component is
removed in the same manner as the first cut,
maintaining adequate reflux to assure separation from
even higher boiling solvents. The batch is thus
continued until all sought-after solvent components
are reclaimed. The unrecovered residues are then
handled in the same manner as those from pot stills
or thin-film evaporators.
Theoretically, any solvent mixture can be separated
by fractional distillation if the equipment design is
adequate. Practical considerations of operating
economics and equipment investment, however,
generally limit efficient separation to solvents having a
boiling point spread,of 20° to 30°C. Even this is an
improvement over" capabilities available in the
recycling industry 20 years ago. By varying solvent
waste feed points, reflux ratios, and use of vacuum, a
great deal of flexibility is created to process many
different solvents previously considered either
uneconomical or impractical.' Quality refined products
are being produced that can be used in almost all
phases of industry, including pharmaceutical
applications to manufacture drugs.
Subsequent processing may involve extraction,
filtering, restabilization, or drying, depending on the
refined solvent specification requirements. The most
common problem associated with refined solvent
quality is excessive moisture, or water. Moisture
contamination may create corrosion problems, or
coating problems with paint solvents, or hydrolytic
breakdown problems with chlorinated solvents.
Several techniques are available to address these
problems.
Since water forms an azeotropic, or constant boiling
mixture, with many solvents, those recyclers with
fractionating capability may use distillation techniques
for moisture removal. Depending on the azeotropic
mixture and the quantity of water to be removed, this
method can be very effective, though usually quite
costly.
Another option available is physical or mechanical
removal. This involves filtering the refined solvent
through an absorbing or adsorbing dessicant.
Anhydrous calcium chloride is sometimes used for
this technique, and can be very effective for removal
of trace water contamination. For refined solvents
containing less than 0.5 percent moisture
contamination, calcium chloride can dry them down to
200 ppm. Disadvantages are that when spent, the
calcium chloride cannot be regenerated, creating a
potential disposal problem, and there is the possibility
of free halogen contamination of the refined solvent,
causing a potential corrosion problem.
Another method effective for trace water
contamination removal is ion exchange resin. This
method uses adsorption, with the water molecules
attaching to the resin, and the subsequent dry solvent
passing through. It has repeatedly demonstrated the
ability to reduce moisture levels from 0.2 percent to
0.3 percent down to less than 100 ppm, and has the
advantage of being able to regenerate. A
disadvantage, though, is that this method is not
effective on refined solvents with more than 0.5
percent moisture contamination.
Probably the best available technology today for
moisture removal is the molecular sieve bed. It
functions by actually trapping the water molecules in
the interstices of the molecular sieve, allowing the dry
solvent to pass through. This method has the
advantage of being able to handle gross amounts of
water contamination (drying from five percent down to
less than one percent), as well as the trace moisture
contaminated solvents (drying from 0.5 percent down
to less than 200 ppm). It also can be regenerated for
continued use.
From a technical point of view, any solvent can be
reclaimed to a point where it can be reused. The only
limiting factor is economics, and with disposal costs
escalating so rapidly, recycling is becoming the
method of choice for a wider range of solvents. In
some cases, the cost for disposal is higher than the
original cost of the virgin product, and once a material
96
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is disposed, it is gone forever, with a corresponding
loss of precious natural resources.
Quality Control
Let's look at what happens to a solvent during the
recycling process to assure quality. First, the waste is
collected, in either drums or bulk tank truck transport,
and sent to the recycling facility. There, the waste is
analyzed to verify that the contents agree with the
waste manifest. Then the waste is pumped to bulk
storage. When enough material has been
accumulated for an economical run, the waste is
processed through the distillation system. The
resulting refined product is then analyzed again to
determine conformance with established specifi-
cations. If further steps are required, such as drying or
restabilization, the product is checked again prior to
pumping to final storage. From there, the refined
solvent is packaged to customer order in either drums
or bulk tanker, with yet another quality control check
before shipment. The still bottoms are also thoroughly
analyzed to measure conformance with fuel blending
specifications.
A typical recycling facility lab is equipped with gas
chromatographs (GCs), Karl-Fischer titrimeters,
calorimeters, and atomic absorption spectro-
photometers, as well as other ancillary equipment
such as pH meters, color testers, and specific gravity
measurement equipment.
The gas chromatograph is the key analytical tool for
quality control in the recycling lab. Various
instruments are available, but a well-equipped lab will
have multiple capability - a unit with a thermal
conductivity detector for macro analysis of solvent
components, a flame ionization detector for analysis of
micro (or components in the 100 ppm to 1,000 ppm
range), and an electron capture detector for even
greater sensitivity (to check for trace PCF
contamination, for instance). The GCs can also be
equipped with automatic integrators and automatic
injection, and controlled by computer to increase
analytical reproducibility and reliability.
The Karl-Fischer titrimeter is used to measure water
content. Depending on analytical technique, the
instrument may be sensitive down to less than 50
ppm.
Color testers and pH meters are used for obvious
purposes, since color is occasionally a quality problem
for customers, and pH can affect corrosion properties
of the refined solvent.
The calorimeter is used to measure BTU content of
the still bottoms, with subsequent wet chemistry
testing for halogen content. Both of these parameters
are key specifications for waste-derived fuel
programs.
Another key parameter for still bottoms blending into
waste derived fuels is heavy metal content, such as
lead, zinc, chrome, etc. Typically, the recycler will use
atomic absorption spectrophotometry to measure
heavy metals.
If refined chlorinated solvents are intended for reuse
in vapor degreasing, stabilizer content is an important
quality control parameter. While some individual
stabilizers can be measured.by gas chromatograph, a
better method for checking total stabilizer content is
through wet chemistry titration of acid acceptance.
If the recycler carefully follows all the quality control
steps, industry is assured of receiving a quality
product, appropriate for almost any use. In my
experience, there are very few applications where
refined solvents cannot be used. While there are
perceptions in the market that refined solvent is not as
good as virgin solvent, this is very seldom true. Even
some of the obvious differences between the two,
such as purity, color, and odor very seldom actually
affect the performance of the solvent during reuse.
Recycling Capacity
By dealing with a recycler equipped to service even
the small generator, the economic and environmental
advantages of recycling can be realized. The solvent
recycling market is relatively mature and well-
established, though in a state of change today. While
some companies have been in business for as long as
50 years, and many for as long as 20 years, there are
very few new entrants to the field. Dramatically
increased regulatory and permitting requirements
make it very difficult to stay in business, let alone
make a new entry. Five years ago, market estimates
indicated about 150 recyclers in business in the
United States. Today, that number is less than 100,
and by 1992 is projected to be less than 50. The
trend in the market is towards consolidation, as larger
companies, with greater assets and resources, absorb
smaller companies unable to comply with the
regulations.
There should still be plenty of capacity available,
though, as no recycler of which I am aware is
operating at more than about 60 percent utilization.
Also, most of the decrease from 100 recyclers to 50
will be via consolidation, i.e., they will be acquired,
and continue to operate, rather than cease to exist.
Therefore, plenty of available opportunity should exist
for generators to take advantage of off-site recycling
within their economic transportation service area,
generally considered to be 300 to 400 miles.
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Selecting a Recycling Facility
We have looked at both custom toll recycling and
open market recycling: the criteria for selecting the
proper method varies with individual needs. A more
important consideration, though, is selection of the
proper company to service your requirements. Several
key factors should be examined. Since the hazardous
waste generator forever retains ultimate liability for the
waste, and many more of us are now subject to the
regulations, this has far reaching implications and
should weigh heavily in deciding where to have
solvent waste recycled.
The refined solvent resold in the marketplace is
considered a product, and is no longer subject to the
provisions of RCRA. Since no solvent waste is 100
percent recoverable, residues still must be managed
properly to minimize risk and potential liability.
In the past, many industrial and governmental waste
generators selected their TSD facility based upon
impressive oral and written assurances and
representations of proper procedures; however, these
assurances were no protection against liability. Then,
most firms began requiring copies of appropriate
permits from those facilities being used or considered
for use. Alas, this has proven no more effective, as
most Superfund priority sites appear to have been
properly permitted during the course of their
operation. Once again, no protection from liability.
How, then, since you as generators retain ultimate
liability for the management of your hazardous waste,
can you minimize the risks of damage to the
environment, or to your company's assets and
reputation? By the way, it is my considered opinion
that those of you who may be categorized as small
generators need to assign as much or more attention
to this decision than do General Motors, IBM, Xerox,
and other corporate giants. As an illustration, at the
Berlin and Farro site in Michigan, cleanup costs of
S14 million were paid by 87 generators. General
Motors' share was $8.4 million, Dow Coming's was
$1.2 million, NL Industries was $129,000, Ford Motor
Company's was $212,000, Grand Trunk Railroad's
was $144,000, and Monsanto's was $100,000. These
costs, which were published in the newspaper, are
embarrassing to the companies involved, as well as
damaging to profitability. Beyond that, however, there
will be no discernible adverse effect. Each considers it
an expensive lesson learned, and business life
continues as normal. How would your company react
to such a penalty or to one of $5,000 $10,000, or
$50,000? In some cases, I dare say that your
business...your whole life would suffer severe
consequences.
As a beginning to your decision making process, I
strongly urge you to inspect those facilities you are
using or considering for use, at least once each year.
No responsibly operated TSD site of which I am
aware would refuse such a visit. Any that would
should be eliminated from consideration.
When inspecting the site, five critical areas should be
addressed:
Owners/Operators of the Site
- The financial status and capabilities should be
examined. General Motors would not have
had to pay $8.4 million to clean up Berlin &
Farro, if Berlin & Farro had not gone bankrupt.
- Are the transporters and other TSD facilities
used by the site in question capable,
reputable, and reliable?
Does the facility have adequate insurance
coverage? Environmental Impairment Liability
insurance is very difficult to obtain today, and is
very costly. Without adequate financial capability,
it is the only protection you have from CERCLA
costs.
Site Personnel
- Is the staff qualified and experienced?
- Do training programs exist to assure
continuance of qualified people operating the
site?
How are documents and records managed?
Poorly maintained records may indicate a poorly-
run facility.
Site Situation
- Is the facility located in a residential area,
subject to the inherent risks and complaints?
- Is the site located where potential spills may
endanger nearby well water? What types of
wastes are handled that may pose ultimate
risk? Your liabilities do not end/begin at the
point in time at which you commence
business. The liabilities are potentially all-
inclusive.
Regulatory Compliance Status
- Are the necessary permits held? Any doubts
can be resolved by the appropriate regulatory
agencies. Copies of the permits should be
examined.
- What is the compliance history of the site? A
consent order or other sign of difficulty does
not necessarily rule out consideration, since
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any site more than eight years old probably
has past problems to correct, but compliance
monitoring in such cases should be examined.
Operations
- Do health and safety practices appear
adequate?
- Is equipment properly maintained?
- Is there secondary, and preferably tertiary,
containment of solvent storage and handling
areas? Is there a spill control plan?
- Is there a contingency plan?
- Are there adequate warning and security
signs?
- Are there internal inspection procedures? Are
they documented? All of these are required of
a properly-run facility.
- Finally, how are the unrecoverable residues
handled? Some residues are suitable for
chemical-based fuels programs, such as
cement kilns. But what happens to those
residues not sent for fuel? Those materials
should be sent to an approved, permitted,
commercial incinerator.
In addition, every recycler is burdened with a water
disposal problem. Most incoming wastes have
associated water contamination to be removed. Also,
water is the most commonly-used medium to clean
out process equipment to prevent cross-
contamination. We send these waters to DuPont in
New Jersey for biological and chemical treatment,
with the resulting effluent being not only
nonhazardous, but meeting drinking water standards.
These practices assure that the portion of waste that
is not recovered as quality product is destroyed, so it
will not come back to haunt us or our customers.
If these five critical areas of concern have been
adequately addressed, you may rest assured that you
have done your job properly, and selected ac-
cordingly.
While recycling can be shown to be an economical
alternative to disposal, our options have deeper
significance. We should also view recycling as a
viable means to conserve increasingly finite
resources, and to preserve our environment for our
children and future generations. We consider
ourselves part of the solution, not part of the problem.
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Chapter 12
Making the Most of Bottoms and Residuals
Steven F. Miller, Ph.D., P.E.
Dames & Moore
San Francisco, CA 94105
Historically, most oil rerefining and solvent recovery
processes have focused on recovery of supernatants
and distillates and consigned the bottoms and
residuals to disposal. That approach often left the
most valuable molecules in the discarded fraction,
which typically went to landfill. The land bans which
began taking effect in November 1986 were expected
to increase solvent recycling. Instead, they appear to
have had the opposite effect. This is because solvent
recyclers that had generally discarded their bottoms to
landfill have now discovered better economics in
sending unrecovered solvents to RCRA fuel blending
programs (e.g., to cement kilns and industrial boilers)
compared with recovering distillates and destroying
the resulting bottoms in commercial incinerators. The
exceptions would include those few recyclers that
have captive incineration capacity.
Actually, halogenated solvents continue to be recycled
because they cannot be consumed directly in RCRA
fuels programs since the halogen levels are too high.
Disposal of the bottoms from these halogenated
solvent distillations via RCRA fuels programs requires
the use of diluents to meet maximum chloride, solids,
and viscosity requirements. Unrecovered
nonhalogenated waste solvents are being used as
those diluents. Thus, recovery of the nonhalogenated
solvents has been the most drastically curtailed.
One oil and solvent recycling company's very
successful waste minimization program focused on
the reuse of waste streams, making possible virtually
total recycle of an increasing variety of hazardous
wastes. The benefit of total recycle was, of course,
reduced cost and liability. The key to the program was
to persistently look for ways to utilize the parts of
process streams which would otherwise become
disposal problems. Of particular interest here were the
distillation bottoms and residuals. What we will be
discussing is not restricted technology, and similar
approaches can be taken by other facilities if they
choose.
The company we will be discussing was originally a
marketer of lubricating oils, which decided to produce
its own base stocks for those lubricants. In the 1950s,
it began collecting and rerefining used lubricating oils
and reselling the resulting oils. It elected to rerefine its
oil by the acid-clay process which was popular at the
time because it produced a very high quality finished
product. Automotive lubrication requirements were
relatively simple in the 1950s, and the used motor oils
contained few additives. Thus, the acid process was
relatively easy to operate. During the 1960s, 1970s,
and 1980s, lube oil additive requirements increased
significantly, which made the acid process more
difficult to operate and increased the quantity of waste
produced.
The acid process, as depicted in Figure 12-1,
consisted of dehydration or heating of the waste oil to
remove water and a light fuel fraction and to crack the
dispersant part of the additive packages in the oil.
Then the oil was cooled and treated with strong acid,
typically 98 percent H2SO4 (sulfuric acid), which
sulfated and precipitated most components which
weren't stable lube oil molecules. Fifteen to 20
percent of the liquid was drawn off the bottom as a
heavy, tarry "acid sludge" waste. This obnoxious
waste, which was high in lead and sulfuric acid, was
neutralized with limestone (CaCOa) prior to landfill
disposal. Many plants in the U.S. simply disposed of
the acid sludge in landfills without neutralization.
Growing environmental pressures in reaction to these
and other disposal practices caused many oil refining
plants which did not neutralize this acid sludge to
close down.
Following this acid treatment step, the supernatant
lube oil fraction was again heated, this time in the
presence of activated clay to remove color bodies.
The spent clay was then separated by filtration and
disposed of in landfills.
The water removed from the process was treated by
addition of lime and alum in a reactor/clarifier, with the
treated water sent to the POTW, and the resulting
lime/alum sludge sent to landfill.
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Figure 12-1. Acid-clay process.
Flare
POTW
> Landfill
H2SO4
I
> Light Oil
Clay
30 Weight Oil
Spent Clay Landfill
Acid Sludge
Landfill
CaCO
All three landfilled materials presented potential long-
term environmental liabilities. At this point, the
company was purchased and I came on board with an
agreement that I would be allowed to modify the
process to eliminate waste generation.
A few attempts were made to recycle the acid sludge
by burning it at a sulfuric acid production plant which
normally produced H2SC>4 by burning sulfur and
supplemental fuels. The acid sludge was
approximately 30 percent sulfate and 70 percent
burnable organic compounds, making it very attractive
to the company which owned the acid plant. This was
technologically feasible, and the company I am
employed by today has actually made arrangements
to recycle very old acid sludge pits by this means.
However, in the case we are now discussing, the
recycle approach involved shipping the acid sludge
about 750 miles via bulk truck, which became
prohibitively expensive.
By January 1982, the facility was modified to operate
a distillation/ clay process, depicted in Figure 12-2,
which had been developed to eliminate production of
the acid sludge waste. Variations of the distillation
process have become the most common waste oil
rerefining processes today. In place of the acid sludge
waste, a viscous, high flash (typically 550°F) bottoms
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Figure 12-2. Distillation clay process.
Flare
Truck Diesel
Used Oil
O
oo oo
Polymeric Waste
Roofing
Asphalt Flux
Clay
Lube Oil
Spent Clay
Kiln
Lightweight Block
Water
Polymer
Oil/Polymer Recycle
POTW
product can be produced which is useful as an
asphalt oil cut-back or asphalt viscosity reducing
agent. At first, the bottoms product, which was called
asphalt flux, went to Phillips Petroleum to be used for
cutting back' road asphalt at about the price of the
road asphalt itself. Shortly thereafter, concern over the
legal definition of "putting bottoms on the ground"
resulted in selling all the asphalt flux to refineries to
cut back roofing asphalt prior to the air blowing steps
in which the final roofing asphalt product qualities are
achieved.
Here we should note that the "impurities" present in
the used motor oils, such as the polymer additives
used to provide multigrade viscosity (e.g., 10W30,
15W40) contributed to final roofing product quality and
that the metals present from additives and from use
(e.g., zinc and lead) catalyzed the air-blowing process,
thus increasing refinery throughput. Arrangement with
its main new refinery customer became a profitable
gallon-for-gallon trade of one gallon of asphalt flux for
one gallon of virgin lubricating oil also produced by
that same customer.
The lime/alum waste water process was replaced by
polymer addition. Combinations of polymer types were
used. The material recovered was recycled to the
asphalt flux tower along with the incoming used oil.
That left only the spent clay waste, containing oil and
color bodies but no significant metals, going as a
nonhazardous industrial waste to landfill. The
company considered hydrotreating the oil as a
substitute for the clay finishing step, as this would
have eliminated potential future landfill liability, but the
capital cost was too high. It therefore contracted with
a plant which burned coal and shale to make
lightweight aggregate for lightweight concrete block
(e.g., cinder block). The plant burned the spent, clay
(which was approximately 30 percent lube oil and
carbon) in place of coal. The 70 percent clay ash was
incorporated in the cinder block product. This proved
beneficial to both parties and thus the last landfill
stream was eliminated.
As the company examined what was achieved via
waste minimization other observations were made.
Along with waste oil it had been receiving caustic
cleaning wastes from the local drum reconditioners
and processing those wastes along with the ordinary
used oil. This stream was rich in paint polymer
stripped from the drum outsides by the caustic
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cleaning process. Bench tests indicated that this
waste stream had only positive effects on both the
asphalt flux product, which was itself already rich in
polymers and on the final roofing product's ductility.
Therefore, other drum conditioners were sought out
as suppliers. These drum reconditioners were
delighted to have an alternative to local landfills. The
search was expanded for other polymeric-bearing
feedstocks which could be made compatible with the
asphalt flux.
At this point, the company's RCRA history is worth
mentioning. It had originally received Part A status as
a generator and treater of acid sludge, a characteristic
waste. Because used oil is typically potentially
contaminated by a variety of listed solvents, the
company expanded its Part A status to include
receiving and processing of such oil, just in case.
Later it further expanded Part A to include permission
to receive listed solvents for recycle or burning for
energy recovery in its industrial process heaters. It
also received approval for caustic and acidic wastes
which it used in the processes. It was then granted
Part B status on the basis of all Part A activities.
Originally, the company had taken measures to
minimize solvents in its feedstocks recognizing that
the contaminated distillates would make less desirable
fuels. Later, with the oil distillation process operating
well, the company became interested in solvent
recycling per se, and thus began to examine individual
solvent waste streams for their compatibility with the
new process. Solvent wastes typically contain
concentrated dissolved and suspended components
and contaminants accumulated in the solvent during
formulation and use, including a range of polymers,
resins, dirts, oils, and greases, etc. The following
approach became apparent:
A polymer or oil-bearing solvent waste could be added
to previously conditioned asphalt flux (550 °F flash
point, prestripped of all light volatile matter) as
depicted in Figure 12-3, the solvent stripped overhead
through a distillation system, and the polymer retained
and recovered in the flux. The extreme temperatures
assured no significantly measurable solvent would
remain in the bottoms product which was then equal
or superior to the original flux product.
Not all solvent wastes are compatible with the flux, so
bench testing of the candidate stream was the key to
success. Initially, it was hard to model the high
temperature operation at the bench and so at first
many streams were rejected, a number of which were
later made compatible.
Recycling waste printing inks became a major activity
at the facility. Most oil-based printing inks recycled
directly as if they were used motor oil. The solvent-
based and solvent-contaminated ink systems were
more difficult, but the majority were compatible with
Figure 12-3. Solvent recycling.
Recovered
Solvent
Solvent
Purification
Solvent Waste
oo oo
Flux Tower
Roofing Asphalt
the asphalt flux product. Certain methylene chloride-
stripped paint wastes and a surprising variety of other
waste streams were discovered to be flux compatible.
Degreasing solvents containing oil and grease (and a
relatively small quantity of dirt) were also flux
compatible.
To review, I have described the evolution of a
company which began as a lube oil marketer, decided
to use waste oil as raw material, and thus became a
waste generator. That company undertook an
ambitious waste minimization program through
utilization of bottoms and residuals, expanded its
RCRA licensing, and thus was able to expand its oil
and solvent utilization. It was always careful in
selecting suitable wastes as feedstocks. Bench and
pilot tests were employed to check compatibility of
residuals with the bottoms product, to maintain
bottoms product quality, and to avoid
coking/decomposition in process units. Unsuitable
waste streams were always rejected.
I believe that the examples of utilization of bottoms
and residuals given here indicate a general direction
which should be further explored in the recovery of
bottoms in valued product streams. If you have such
streams in your plant or are a recycling facility, I
encourage you to persist in finding a home for your
liabilities in a saleable product stream.
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Chapter 13
Treatment: Solvent Wastestreams
Robert H. Salvesen
Robert H. Salvesen Associates
Red Bank, NJ 07701
Treatment of used solvents is an option often selected
as a means of waste minimization or source
reduction. While the preferred treatment is recycling
for the original use, other technologies are available
which enable solvents to be used for other purposes.
General types of solvents (excluding halogenated
materials) utilized by industry and commercially
available treatment technologies are discussed in this
chapter.
Introduction ,
Solvents are used in many industries, mainly for
cleaning and as reaction media. Due to'their generally
high initial cost and recent mandates to minimize
waste generation and disposal, it is prudent to
consider how to maximize their recycle and reuse. A
separate paper on recycle and reuse is included in
this proceedings document. -
Solvent treatment technologies (excluding recycle),
which can provide reuse and disposal options, will be
discussed in this chapter. The major topics to be
covered are:
Description of solvents used by various industries.
- Metal cleaning
- Paints, coatings, inks
- Process
- Adhesives
Commercially available treatment technologies.
- Downgrading/waste exchange
- Fuel use in boilers and cement & asphalt kilns
- Stripping
- Incineration
- Biodegradation
- Oxidation
- Encapsulation .:
Examples of the above will also be provided.
Description of Solvents Used by Various
Industries
This section will cover the major solvents used in
industry, but is not intended as an all-inclusive
discussion.
Metal Cleaning
Hydrocarbons, halogenated solvents, oxygenated
solvents, and mixtures of these solvents are used, for
cleaning of metals containing carbon, oils, grease, dirt,
etc., and for paint stripping. Except for the
halogenated materials, these solvents are described
briefly below:
Hydrocarbons
Mineral spirits, naphthas, toluene, and xylene are the
most common types.
Oxygenated
Ketones (MEK, MIBK), esters (ethyl or butyl acetate),
alcohols (methyl, ethyl, isopropyl), glycol ethers
(ethylene gylcol), phenols, and cresols are the major
types used.
Mixtures
Mixtures of the above materials as well as chlorinated
solvents are used mainly for tough cleaning and paint
stripping. Proprietary solvents often contain special
additives such as emulsifiers, lanolin, colorants, and
odorants.
Paint, Coatings, and Ink
Paint, coating, and ink industries mainly utilize
hydrocarbons and oxygenated solvents as vehicles
and solvents. The latter are also widely used for
cleanup operations.
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Process
A wide variety of processes utilize a broad range of
solvents as reaction media, for finishing, and for
cleanup operations. Several examples are:
Chemical reactions are often carried out in the
presence of solvents such as toluene, xylene,
MEK, etc. These solvents are also used to clean
up equipment. Many processes already include
solvent recycle.
In the manufacture of Pharmaceuticals, for
example, drugs encapsulated in gelatin often
require a finishing step such as washing with a
high-purity hydrocarbon solvent.
Decaffination of coffee includes an extraction
using high-purity hexane or heptane. These
solvents are recycled.
Adhesives
For the manufacture and application of adhesives,
solvents are essential. Hydrocarbons as well as
oxygenated solvents are used. Generally low boiling,
volatile solvents are desired.
Commercially Available Treatment
Technologies
Downgrading/Waste Exchange
Downgrading is the term applied when a contaminated
solvent is utilized for another purpose within a plant.
Waste exchange is the term used when a used
solvent is sold or exchanged for credit or another
material in another plant or industry. There are a
number of community, industry, environmental, and
government agencies operating waste exchanges.
Both activities involve used solvent which can be
employed in another operation with little or no
treatment. Several examples follow:
Precision bearings need very high-purity solvents
for cleaning. The solvents acquire very little
contaminant in usage and can be downgraded or
exchanged for other less demanding cleaning
operations.
A special grade of mineral spirits is often used as
a calibrating fluid for pumps, fuel nozzles, meters,
etc. This material can readily be downgraded or
exchanged for cleaning purposes. The military and
other industries utilize large volumes of this type
of calibrating fluid.
Fuel Use
Boilers in industry, operating on any type of fuel, can
be adapted to burn waste solvents, provided certain
requirements are satisfied. Generally, boiler fuels
requite a minimum flash point of about 135°F. Thus,
only a few solvents such as high flash mineral spirits
(minimum flash point of 140°F) are suitable. The only
treatment required is to blend the used solvent with
whatever existing liquid fuel is employed. If gas or
solid fuels are normally burned, a separate fuel
handling system and appropriate burners would be
required.
Cement Kilns
Cement kilns consume a lot of fuel and operate at
sufficiently high temperatures (about
2,100°C/3,844°F) to decompose most organic
compounds including halogenated solvents. Studies
by EPA have indicated that wet kiln operators
throughout the U.S. and Canada have successfully
burned many types of organic wastes. Costs for
disposal by this method may range from $0.10 to
0.50/gal, but this is usually much less than alternate
treatment or disposal options.
Asphalt Kilns
Almost any low-cost liquid material can be burned in
asphalt kilns as fuel. However, since the ingredients
are not alkaline like cement, these kilns are not
capable of handling halogenated solvents.
Stripping
Mixtures of organic solvents and oils can be treated
by stripping the solvent to recover both fractions for
use as fuels or other purposes. Several examples
follow:
Hydraulic systems are often cleaned out with
solvents such as chlorinated or freon solvents. By
steam, stripping the solvent from the oil, the
solvent can be reclaimed and the oil burned as a
fuel.
Used anti-freeze is stripped of water and the
remaining ethylene glycol burned as a fuel.
Soils and other solids contaminated with volatile
solvents can often be stripped by passage of .air
through these media. Depending upon the
concentrations of solvents in the air, the exhaust
stream may be vented, incinerated, or passed
through an absorbent such as activated carbon.
The solvent can be regenerated from the latter by
steam stripping.
Incineration
Treatment and disposal of used solvents by
incineration is often a last resort for low flash and
mixed solvents. Except for incineration by cement or
asphalt kilns as noted above, this method is generally
quite costly due to high operating and emission
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control costs. The major types of incinerators (along
with brief comments on each) are described below.
Vortex - This is a relatively simple unit and occupies
little area for the throughput achieved. A high-velocity
air jet atomizes the feed and causes a spiral-flame
effect. This flame insures a long residence time which
generally assures fairly high combustion efficiency.
Most operating problems are caused by refractory
failure due to inadequate temperature control. This is
caused by variations in feed quality or slagging.
Erosion through impingement of materials o'n the
internals is also a major problem. Incineration of
halogenated materials requires efficient gas treatment.
Rotary Hearth - This unit is a slowly rotating,
refractory-lined chamber. The design is similar to a
vortex incinerator except that it is horizontal and
rotates. The advantage over a vortex incinerator is
that the rotary hearth can handle solids. Problems with
linings similar to those of vortex incinerators can
occur.
Rotary Kiln - This unit can handle a wide variety of
liquid and solid wastes. Many units have an
afterburner if the outlet temperature from the main
chamber is expected to fall below 800°C. Refractory
linings and mechanical stresses are the major
operating problems.
Multiple Hearth - This is a vertical unit with grates
through which the wastes move from top to bottom
and burn in successive stages. Liquid and semi-solid
wastes may be burned. Rotating arms or tines move
the waste around. In the upper stages, rising hot
combustion gases dry the incoming materials. Lining
materials and mechanical stresses are the major
problems in operation.
Fluidized Bed - In this unit, wastes to be burned may
be liquid, semi-solid, or solid. The material is mixed
into a fluidized granular bed of special sand (1 to 3
mm diameter) which is heated to combustion
temperature's. This method assures good mixing of
the wastes and hot gases to provide complete
combustion. Compressed, preheated air is the
fluidizing agent. The fluidizing bed may contain special
absorbents, i.e., limestone, to react with combustion
gases such as HCI, SO2, etc., to reduce or eliminate
effluent treatment requirements. Generally, cyclones
are required to remove entrained solids from the off-
gases. This type of unit is very flexible, but does have
problems with linings and slagging in the fluidizer,
depending upon the design and materials combusted.
Circulating Bed - This unit is an alternate to fluid bed
combustors and reportedly: operates at higher
velocities with fine sorbents to obtain a more compact
unit that is easier to feed. Such units operate at high
combustion efficiencies and produce lower emissions
using less sorbent materials. Generally, no off-gas
scrubber is required and heat recovery can be
achieved to produce steam, electricity, hot water, or
hot air. This unit is very flexible and can burn
gaseous, liquid, slurry, and solid wastes, but has
problems similar to those noted above for fluid bed
combusters.
Fume - These systems are used to burn off vapors
prior to emission to the atmosphere where recovery is
not desired. Incineration facilities work best on air
streams which contain solvents at 25 percent of their
lower explosive limit (LEL). The minimum acceptable
concentration is 15 percent of LEL. (For a typical
solvent stream with a one percent LEL, this amounts
to a 1,500 to 2,500 ppm concentration.) At 25 percent
LEL, such equipment can provide a high calorific
credit for the solvent burned. Incinerators are not
efficient at low concentration effluents from, for
example, a spray booth. Facilities such as paint or
coating bake ovens, where solvent vapor
concentrations are high, could profitably utilize fume
incinerators.
Biodegradation
Biodegradation of organic materials is a natural
process that has been practiced on a broad range of
substances. Bacteria and microorganisms to
decompose almost anything can be found in nature.
Most organisms are ubiquitous, but for commercial
use in treatment and disposal of used wastes such as
solvents, the rates of decomposition of the specific
wastes and how to maximize their rate of degradation
in the desired environment must be defined.
Extensive studies on petroleum products have shown
both land-based and water-borne organisms can
biodegrade these materials in as little as one to six
months. The decomposition products are humic acids
which generally are beneficial to most soils.
This treatment method has potential for the following
solvents:
Aliphatic hydrocarbons
Ethers
Alcohols
Glycols/Epoxides
Esters
Benzene
Phenols
Biodegradation is not a panacea for all types of
solvents or other wastes. However, the potential for
this method has not been fully utilized and needs
extensive testing to define acceptable conditions for
various substances.
Oxidation
Oxidation by organisms, air, ozone, and other
oxidizing agents is commonly used for treatment of
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many substances. In recent years, claims have been
made for accelerating biodegradation of organics such
as solvents by addition of peroxides, or other oxidizing
agents.
Encapsu/atfo/7
An optional means of land disposal of wastes such as
paint sludges containing paint thinners is by means of
encapsulation. Agents such as fly ash, silica gel,
epoxy resins, glass, and other vitreous materials can
be used for encapsulation. While these treatment
methods are mainly used for sludges, some such
materials can contain solvents. Caution should be
used in encapsulating these materials since the
solvents may become mobile over a period of time.
Conclusions
Used solvents from most industrial operations can be
treated for recycle, reuse, or disposal. Recycle
normally involves practices such as segregation and
redistillation to produce solvents meeting new product
specifications. Other treatment methods such as
blending for fuels, stripping, incineration,
biodegradation, oxidation, and encapsulation are viable
options for handling various types of used solvent.
Commercial experience has proven the benefits of
these treatment technologies.
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Chapter 14
Treatment of Spent Solvent Wastewaters: Focus on Changing Economics
David Pepson
Versar, Inc.
Springfield, VA 22151
Introduction
Treatment technologies that are commonly used to
treat spent solvent wastewaters are steam stripping,
carbon adsorption, and biological treatment. These
technologies have also been determined by EPA to
represent Best Demonstrated Available Technology
(BOAT) for wastewaters containing any of the 25
spent solvents that are defined under the hazardous
waste listings of F001 through F005. All of these
technologies are demonstrated and a considerable
amount of information exists on the waste
characteristics that affect performance. Therefore, it
needs to be evaluated regarding technology selection
and use. One area of treatment design that has not
been examined to any great extent, however, is
whether past cost optimization studies are still valid in
view of changes in treatment requirements associated
with the land disposal regulations (LDR) and other
regulations under the Hazardous and Solid Waste
Amendments (HSWA) of 1984.
The principal purposes of this paper are to examine
some of the new cost elements associated with each
of the technologies mentioned previously and to
provide some "food for thought" in designing
new/modifying existing treatment systems. This paper,
while providing some information on the operation and
applications of these technologies, will focus on the
changing economics of wastewater treatment and
associated changes "in the selection and sizing of
these technologies. Following a discussion of each of
these technologies, I have performed an optimization
analysis which shows the impact of the land disposal
restrictions rule on treatment economics.
Steam Stripping
Description
Because the term "steam stripping" is often used
interchangeably with batch distillation, an important
first step in describing the operation and application of
this technology is the definition of terms. Steam
stripping, as used here, and described in EPA's spent
solvent final rule of November 1986, refers to a type
of distillation technology that is used to treat
wastewaters that contain low concentrations of volatile
organic compounds. It is distinguished in two
significant ways from the technology of batch
distillation which uses steam to strip volatile
compounds. First, steam stripping is used for low
concentration wastestreams, with roughly less tha,n
one percent spent solvent content, compared to batch
distillation which generally is used for waste§
containing 50 to 90 percent spent solvents. Secqnd,
the primary purpose of steam stripping is to comply
with wastewater treatment standards. The organics
removed can be recovered, however, and somewhat
offset treatment costs. For batch distillation, the
primary purpose is economic recovery of spent
solvents.
Application
A stream stripping unit consists of a boiler, a stripping
section, a condenser, and a collection tank. The
number of equilibrium stages needed (either in the
form of trays or packing) in the stripping sectipn
depends on the particular waste to be treated.
In practice, steam stripping is used by a number, of
manufacturing facilities including those that
manufacture agricultural intermediates or
Pharmaceuticals, where solvents are used as carrier
solvents. Some commercial solvent recovery facilities
use steam stripping where wastes have significant
concentrations of water. Facilities also use steam
stripping to treat residuals from solvent extraction
recovery processes.
Steam stripping can be used to treat most of the FQ01
to F005 spent solvent compounds. EPA based BOAT
on steam stripping for only 12 of the 25 spent
solvents; however, the rulemaking record makes clear
that for many of the compounds, treatment data were
not available for steam stripping. Regardless, steam
stripping can be used, provided the required
standards can be achieved. Waste parameters that
affect the selection of steam stripping are filterable.
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solids, oil and grease, total organic carbon, and other
hazardous constituents that are minimally volatile.
rather, to the appropriate federal, state, and local
regulations.
Selection and Optimization Considerations
For facilities that plan to use, or are using, steam
stripping as a treatment technology, a number of
design and operating factors should be re-examined in
light of the LDR and other regulations under HSWA.
First, and foremost, facilities need to examine the size
of the steam stripper. Prior to the land disposal rule,
many facilities would size steam strippers for 90 to 95
percent removal, and then use carbon as a polishing
step. Under EPA's "derived from" rules, the spent
carbon is also a hazardous waste that will now require
treatment prior to land disposal. As a consequence of
the treatment costs associated with the spent carbon,
it may now be more cost effective to increase the size
of the steam stripper and either eliminate the carbon
system or significantly reduce the pollutant loading on
the carbon system so that disposal costs are
significantly reduced.
Another aspect to consider in the design of steam
strippers is the type of trays. Some trays provide
better contact and, therefore, increased efficiency.
They may be more difficult to clean, however, and as
a consequence, generate larger quantities of material
to dispose. Again, under EPA's "derived from" rule,
the cleaning waste is also hazardous. Along this same
line, facilities may also want to consider pretreatment
with polishing filters to reduce fouling and associated
cleaning costs.
EPA also has proposed regulations which govern air
emissions from steam strippers (as part of the
Hazardous and Solid Waste Amendments of 1984,
Section 3004). As a consequence, facilities still in the
planning stages should investigate various
optimization scenarios for the stripper condenser.
Examples include comparing the costs of chilled water
versus the use of carbon adsorption downstream from
the condenser. Another possibility is a larger
condenser instead of add-on carbon adsorption to
remove hazardous organic compounds. It would also
be prudent to consider how you could modify the
system if regulations were to become more stringent.
Given the fact that many areas of the country are
looking to further reduce VOC air emissions, facilities
may want to build systems that can easily be
modified. For example, you may want to pipe the
system so that a second condenser could be easily
retrofitted.
A final point regarding the use of steam stripping is
that many of the facilities that use this technology will
discharge the streams to POTWs or surface waters
covered by an NPDES permit. These discharges
would not be subject to land disposal restrictions, but
Carbon Adsorption
Description
Carbon adsorption can be used to treat spent solvent
wastewaters by adsorbing the organic compounds
onto specially prepared carbon granules. Activated
carbon is derived from virtually any carbonaceous
material including wood, coal, coke, and petroleum
residues. The treatment system itself is quite simple,
consisting of a packed column in which the
wastewater generally enters from the top and
discharges after the distribution plate. This plate
serves to minimize the potential for channeling in the
carbon bed.
Carbon can be purchased with a range of properties
depending on the particular needs. These properties
include surface area, pore size, particle size,
hardness, and iodine numbers. The latter
characteristic refers to a bench-scale test where the
amount of iodine adsorbed is measured and used as
an indicator of adsorption for low molecular weight
organics.
Application
Carbon adsorption can be used for a wide range of
F001 to F005 spent-solvent wastewaters. EPA
determined that carbon adsorption, alone or in
combination with other technologies, represents BOAT
for eight of the 25 F001 to F005 compounds. The
waste parameters that should be considered in
selecting this technology are type and concentration
of organic compounds, filterable solids content, oil and
grease, and the type and concentration of various
metals present in the waste.
Selection and Optimization Considerations
An important consideration regarding whether to use
carbon adsorption is the regeneration and/or disposal
of the carbon. As noted earlier, the spent carbon is
considered a hazardous waste under EPA's "derived
from" rule and facilities would therefore need to
comply with RCRA provisions and incur associated
costs for storing, transporting, and disposing of this
material.
As a result, an important new consideration in
optimizing the size of the beds is the number of times
that the spent carbon has to be transported. It might
be advantageous to increase the size of the beds to
minimize the number of times that the spent carbon
has to be transported as a hazardous waste. Of
course, these costs would need to be compared with
other offsetting costs including higher pumping costs
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associated with the greater pressure drop across the
larger bed.
Another factor that plays an important role in cost
optimization is the type of carbon selected. It may "be
possible to use a carbon that is more expensive
initially, but can be used for longer periods of time
before regeneration.
Biological Treatment
Description
Biological treatment involves the use of naturally-
occurring, acclimated, or genetically-altered micro-
organisms to degrade organic contaminants in the
wastewater. Aerobic treatment is the most common,
wherein organic constituents are converted by
microorganisms to carbon dioxide, water, and cell
protein. In the absence of oxygen (known as
anaerobic treatment), wastes are converted to
methane and carbon monoxide.
Application
Biological treatment can be used for most of the F001
to F005 spent solvents. EPA has determined that this
technology, alone or in combination with steam
stripping or biological treatment, represents best
demonstrated available technology for nine of the 25
F001 to F005 spent solvents. Waste parameters that
affect the selection of this technology include filterable
solids, oil and grease, the presence of toxic metals,
surfactants, and the presence of refractory organic
compounds.
Selection and Optimization Considerations
Biological treatment can result in the generation of
solid residuals that would be classified as hazardous
under EPA's "derived from" rule. Accordingly,
facilities that plan to use this technology need to
evaluate costs associated with storage, transport, and
disposal of these hazardous residuals. Facilities may
also want to take a closer look at technologies that
have been developed more recently, such as wet air
oxidation to replace or enhance biological treatment.
Wet air oxidation would likely be more energy
intensive than biological treatment, for example, but
the fact that less residual material is generated may
result in an overall savings. Additionally, biological
treatment of certain compounds can result in air
emissions which the EPA is studying with respect to
the need for regulation. A final point with regard to the
use of biological treatment is that it may be possible
to delist the treated residuals. If this is the case, then
the economics would not change significantly.
'
Cost Optimization Example
Below is a cost optimization example that compares
treatment costs for two systems prior to and after
implementation of the land disposal requirements.
While this example uses a number of simplifying
assumptions, it provides a good illustration of the
potential impact that the land disposal rules can have
on treatment costs. The particular wastestream being
evaluated is one that contains 500 mg/L of methylene
chloride and trace amounts of other constituents.,
including filterable solids and oil and grease. The
technologies being compared are steam stripping (10-
tray column) in combination with carbon adsorption
and steam stripping alone, but with 50 equilbrium
stages. The cost analysis has been simplified and
includes only capital costs for the various technologies
and annual costs associated with disposal of the spent
carbon. An actual cost analysis would be much more
complex, including such annual costs as regeneration
of carbon prior to the need for disposal (remember
also, that any wastewater generated as part of
regenerating the carbon is also hazardous), disposal
costs for non-reuseable material from steam stripping;
and costs for air emission controls on the steam
stripper. Many of these annual costs have been
considered in past optimization studies.
In this example, the facility needs to reduce the
concentration of methylene chloride from 500 mg/L to
0.5 mg/L to comply with federal wastewater treatment
requirements. It is assumed that a 10-tray column can
reduce the methylene chloride content by 99 percent
to 5 ppm, and that addition of the carbon system will
achieve the 0.5 mg/L standard. It is also assumed a
50-tray steam stripper can achieve a reduction of 99.9
percent and, therefore, achieve the treatment
standard alone without the need for carbon
adsorption. Prior to the LDR, one could assume min-
imal costs for land disposal; however, today the
treater must include treatment costs for incineration at
an approved incinerator prior to land disposal of the
spent carbon. The analysis assumes that the carbon
is regenerated once every seven days, and after the
fifth regeneration cycle it is no longer useful and must
be disposed as a hazardous waste. Disposal costs are
$300/drum and transportation costs are $500 per trip.
As shown in Table 14-1, the inclusion of treatment
costs due to the LDRs reverses the treatment
selection picture. Without these costs, the
combination system (i.e., steam stripper plus carbon
adsorption) is $76,000 less than the 50-tray steam
stripper; with these increased treatment and disposal
costs converted to capital dollars, the steam stripper
is $212,000 less expensive than the combination
system based on a present-worth analysis.
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Tablo 14-1. Cost Optimization Summary
Method Case I" Case II *
Steam stripping (10 trays) $224,000 $512,000
and carbon adsorption
Steam stripping (50 trays) $300,000 $300,000
" Assumes minimal cost for disposal of spent
carbon.
* Includes cost for incineration of spent carbon prior
to land disposal.
Conclusions
Effective treatment of spent solvent wastewaters can
be accomplished with a variety of individual
technologies or technology trains. With the
promulgation of the land disposal restriction rules and
other regulations being developed under the
Hazardous and Solid Waste Amendments of 1986,
facilities may want to re-examine the economics of the
wastewater treatment technologies either planned or
now being used.
One important aspect of these recent regulations may
well be that past practices of including polishing or
back-up systems as part of treatment trains is no
longer cost effective. Under today's requirements,
facilities may find improved control systems to be a
better alternative. One possibility is continuous
monitoring of the wastestream and automatic
diversion to holding tanks when the waste does not
comply with regulatory requirements.
U.S. GOVERNMENT PRINTING OFFICE* 993 -750 -002/ 60117
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