&EPA
Environmental Protection
Agency
industrial environmental
Research Laboratory
Cincinnati OH 45268
EPA 600 2-78 004f
April 1978
Research and Development
Source Assessment:
Reclaiming
of Waste Solvents,
State of the Art
Environmental Protection
Technology Series
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-78-004f
April 1978
SOURCE ASSESSMENT:
RECLAIMING OF WASTE SOLVENTS
State of the Art
by
D. R. Tierney and T. W. Hughes
Monsanto Research Corporation
Dayton, Ohio 45407
Contract No. 68-02-1874
Task Officer
Ronald J. Turner
Industrial Pollution Control Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory-Cincinnati, U.S. Environmental Protection
Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency> nor does mention of
trade names or commercial products constitute endorsement or
recommendation for use.
XI
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FOREWORD
When energy and material resources are extracted, processed,
converted, and used> the related pollutional impacts on our
environment and even on our health often require that new and
increasingly more efficient pollution control methods be used.
The Industrial Environmental Research Laboratory - Cincinnati
(lERL-Ci) assists in developing and demonstrating new and
improved methodologies that will meet these needs both effi-
ciently and economically.
This report contains an assessment of air emissions from the
reclaiming of waste solvents. This study was conducted to pro-
vide a better understanding of the distribution and character-
istics of emissions from reclaiming operations. Further infor-
mation on this subject may be obtained from the Organic Chemicals
and Products Branch, Industrial Pollution Control Division.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
111
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PREFACE
The Industrial Environmental Research Laboratory (IERL) of the
U.S. Environmental Protection Agency (EPA) has the responsibility
for insuring that pollution control technology is available .for
stationary sources to meet the requirements of the Clean Air Act,
the Federal Water Pollution Control Act, and solid waste legis-
lation. If control technology is unavailable, inadequate, or
uneconomical, then financial support is provided for the develop-
ment of the needed control techniques for industrial and extrac-
tive process industries. Approaches considered include: process
modifications, feedstock modifications, add-on control devices,
and complete process substitution. The scale of the control
technology programs ranges from bench- to full-scale demonstra-
tion plants.
IERL has the responsibility for developing control technology for
a large number of operations (greater than 500) in the chemical
and related industries. As in any technical program, the first
step is to identify the unsolved problems. Each of the indus-
tries is to be examined in detail to determine if there is
sufficient potential environmental risk to justify the develop-
ment of control technology by IERL.
Monsanto Research Corporation (MRC) has contracted with EPA to
investigate the environmental impact of various industries that
represent sources of pollutants in accordance with EPA's respon-
sibility, as outlined above. Dr. Robert C. Binning serves as
MRC Program Manager in this overall program, entitled "Source
Assessment," which includes the investigation of sources in each
of four categories: combustion, organic materials, inorganic
materials, and open sources. Dr. Dale A. Denny of the Industrial
Processes Division at Research Triangle Park serves as EPA Pro-
ject Officer for this series. Reports prepared in this program
are of two types: Source Assessment Documents and State-of-the-
Art Reports.
Source Assessment Documents contain data on pollutants from
specific industries. Such data are gathered from the literature,
government agencies, and cooperating companies. Sampling and
analysis are also performed by the contractor when the available
information does not adequately characterize the source pollu-
tants. These documents contain all of the information necessary
for IERL to decide whether a need exists to develop additional
control technology for specific industries.
iv
-------
State-of-the-Art Reports include data on pollutants from specific
industries which are also gathered from the literature, govern-
ment agencies and cooperating companies. However, no extensive
sampling is conducted by the contractor for such industries.
Results from such studies are published as State-of-the-Art
Reports for potential utility by the government, industry, and
others having specific needs and interests.
This study of the reclaiming of waste solvents was conducted for
the Organic Chemicals and Products Branch, Industrial Pollution
Control Division, lERL-Cincinnati. Mr. Ronald J. Turner served
as EPA Task Officer.
v
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ABSTRACT
This document reviews the state of the art of air emissions from
the reclaiming of waste solvents. The composition, quantity,
and rate of emissions are described.
Waste solvents are organic dissolving agents which are contami-
nated with suspended and dissolved solids, orgariics, water, other
solvents, and/or any substance not added to the solvent during
its manufacture. Reclaiming is the process of restoring a waste
solvent to a condition that permits its reuse. Industries that
produce waste solvents include solvent refining, vegetable oil
extraction, polymerization processes, and cleaning operations.
Hydrocarbon and particulate emissions result from the reclaiming
of waste solvents. Emission points at solvent reclaiming plants
are storage tank vents, condenser vents, incinerator stacks and
fugitive losses.
A representative plant was defined in order to determine the
source severity of emissions from the solvent reclaiming industry.
Source severity was defined as ratio of the maximum ground level
concentration of a pollutant divided by a hazard factor. Ambient
air quality .standards were used as hazard factors for criteria
pollutants; modified threshold limit values were used as hazard
'factors for noncriteria pollutants. A representative plant was
found to have a hydrocarbon source severity of 0.31 and a par-
ticulate source- severity of 0.0085. Using selected solvents as
noncriteria pollutants ranging from acetone to butanol, source
severities ranged from 0.0063 to 0.05. Approximately 78 persons
are affected by air emissions from a representative solvent
reclaiming operation in the area surrounding the operation in
which the source severity is 0.1 or greater.
Control equipment for hydrocarbon emissions includes floating
roofs, refrigeration, and conservation vents for storage tanks,
and packed scrubbers and secondary condensers for distillation
units. Particulate control from incinerator stacks is accom-
plished with wet scrubbers.
This report was submitted -in partial fulfillment of Contract
68-02-1874 by Monsanto Research Corporation under the sponsor-
ship of the U.S. Environmental Protection Agency.
VI
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CONTENTS
Foreword iii
Preface iv
Abstract vi
Figures viii
Tables ix
Abbreviations and Symbols xi
Conversion Factors and Metric Prefixes xii
1. Introduction 1
2. Summary 2
3. Source Description 4
Process description 7
Materials flow . 17
Geographical distribution 17
4. Emissions 25
Selected pollutants 25
Emission factors 26
Definition of a representative source 29
Environmental effects 30
5. Control Technology 34
State of the art 34
Future considerations 37
6. Growth and Nature of the Industry 38
Present technology 38
Emerging technology 38
Industry production trends 39
References 40
Appendices
A, Names and locations of private contractors
reclaiming waste solvents in the United
States 44
B. Results and samples calculations at presurvey
sampling at a private contractor solvent
reclaiming plant 47
Glossary 53
Vll
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FIGURES'
Number Page
1 General reclamation scheme for solvent reuse 7
2 Cone settling tank for removal of undissolved
solids from waste solvent . 11
3 Distillation process for solvent reclaiming 12
4 Thin-film evaporator 13
5 Barometric condenser with steam ejector
for distillation 14
6 Incinerator for liquid waste disposal 16
7 Reclaiming of solvent from vegetable oil extraction
with direct feedback to main process 18
8 Reclaiming of single-component ink solvent
without distillation 19
9 Solvent reclaiming process used by a private
contractor 20
10 Process schematic and equipment diagram of a
solvent recovery unit 21
11 Material balance for the reclaiming of waste
solvents 22
12 Geographical distribution of solvent reclaiming
operations in the United States '.' . . 23
13 Typical countercurrent vent gas scrubber 35
Vlll
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TABLES
Number Page
1 Distribution of U.S. Solvent Recovered by
Industry . 5
2 Solvent Reclamation by Industry ........... 6
3 Factors Determining the Suitability of Initial
Treatment Methods . 8
4 Analysis of Sludge from Solvent Reclaiming by
Private Contractors 16
5 State Distribution of Solvent Reclaiming
Operations .............. 24
6 Emission Factors for Solvent Reclaiming . . 27
(•- - .
7 Contribution of Criteria Pollutants from
Solvent Reclaiming to National Stationary
Source Emissions .................. 27
8 Solvent Reclaiming Contributions to State
Emissions of Criteria Pollutants ..... 28
9 Population Densities for Randomly Selected
Plants Reclaiming Waste Solvents .... 29
10 Emission Height Data for Private Contractors
Reclaiming Waste "Solvents 30
11 Summary of Data for a Representative Plant 31
12 Emission Rate, XmaX, *max and Source Severity
for Emissions from a Representative Solvent
Reclaiming Plant 32
i
13 Source Severity for Total Hydrocarbons Emitted
from a Representative Plant 32
14 Threshold Limit Values for Selected Solvents 33
15 Source Severity for Selected Solvents 33
ix
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TABLES (continued)
Number Page
16 Affected Population for a Representative Plant .... 33
17 Source Severities for Reclaiming Plants
With and Without Control Equipment 37
18 Growth Rates for Oxygenated Solvents 39
x
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ABBREVIATIONS AND SYMBOLS
C — diameter factor
Cap — production capacity
D — tank diameter
e — 2.72
E — emission factor, g/kg
E1 — emission factor, Ib/ton
F — hazard exposure level
Fg — equivalent gasoline working loss
Fp — paint factor
H — effective emission height
H1 — tank outage
K — equilibrium constant
KT — turnover factor
L — total petrochemical loss
Lj — petrochemical loss
Ly —'equivalent gasoline breathing loss
M — molecular weight of chemical stored
N — number of turnovers per year
P — vapor pressure of material stored at bulk
temperature
Q — mass emission rate
S — source severity
t — averaging time
tQ — short-term averaging time
AT — averaging ambient temperature change
TLV — threshold limit value
u — average wind speed
V — tank capacity
W — liquid density of chemical stored
Xmax — maximum ground level concentration
X_ — time-averaged ground level concentration
Xmax — time-averaged maximum ground level concentration
XI
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CONVERSION FACTORS AND METRIC PREFIXES
CONVERSION FACTORS
To convert from
Barrel (bbl, 42 gal)
Degree Fahrenheit (°F)
Degree Celsius (°C)
Foot (ft)
Kilogram (kg)
to
Kilometer2
Meter (m)
Meter3 (m3)
Meter3
Meter3
Metric ton
Metric ton
(km2)
\ --- /
(m3)
(m3)
Milliliter (mJl)
Pounds-force/inch2
(psi)
Pound-mass (Ib mass)
Meter3
Degree Celsius
Degree Fahrenheit
Meter
Pound-mass (Ib mass
avoirdupois)
Mile2
Foot
Foot3
Gallon (U.S. liquid)
Liter (a)
Pound-mass
Ton (short, 2,000 Ib
mass)
Meter3
Pascal (Pa)
Kilogram
Multiply by
tc =
1.590 x 10
o
-1
- 32)/1.8
= 1.8 tc + 32
3.048 x 10"1
2.205
3.860 x 10-1
3.281
3.531 x 101
2.642 x 102
1.000 x 103
2.205 x 103
1.102
1.000 x 10~6
6.895 x 103
4.536 x ID"1
METRIC PREFIXES
Multiplication
Prefix Symbol factor
Kilo k 103
Milli m 10~3
Example
Ikg=lxl03 grams
1 mg = 1 x 10~3 gram
Standard for Metric Practice. ANSI/ASTM Designation:
E 380-76e, IEEE Std 268-1976, American Society for Testing and
Materials, Philadelphia, Pennsylvania, February 1976. 37 pp.
XII
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SECTION 1
INTRODUCTION
Organic solvents are used by industry for extractions, for clean-
ing, and as chemical mediums or intermediates. To meet the
variety of industrial needs, solvents are available as halogen-
ated, aliphatic, and aromatic hydrocarbons, as alcohols, esters,
glycol ethers, ketones, and nitroparaffins, and as miscellaneous
other compounds such as tetrahydrofuran. This classification
includes solvents such as methyl ethyl ketone, benzene, per-
chloroethylene, and isopropanol.
A solvent which is not consumed during industrial use will
usually become contaminated and therefore, will be unacceptable
for further use. If used solvents are reclaimed, they can be
reused for their original purpose or for different industrial
needs. The reclaiming of waste solvents has become important
since solvent supply and cost are dependent upon the petroleum
industry. The rising cost of virgin solvents and the cost of
waste solvent disposal have provided an incentive for industry
to recover their solvents for reuse.
The purpose of this study is to assess the atmospheric emissions
from the reclaiming of waste solvents. The composition, quan-
tity, and rate of emissions are described.
This document is divided into six sections. Section 2 summarizes
the major findings of this study. Section 3 provides a detailed
description of the solvent reclaiming industry. Section 4 gives
data on emissions and provides an assessment of the environmental
impact of the source on the basis of source severity and affected
population. Section 5 discusses present and future emission con-
trol technology for the solvent reclaiming industry. Section 6
relates the growth and nature of the industry.
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SECTION 2
SUMMARY
Waste solvents are organic dissolving agents which are contami-
nated with suspended and dissolved solids, organics, water,
other solvents, and/or any substance not added to the solvent
during its manufacture. Reclaiming is the process of restoring
a waste solvent to a condition that permits its reuse. Reclaim-
ing is accomplished by removing materials that have contaminated
the solvent during industrial use. Recovery is another term used
to describe the process of restoring a waste solvent for the pur-
pose of reuse.
ir
Industries that produce waste solvents include solvent refining,
vegetable oil extraction, polymerization processes, and cleaning
operations. From a technological standpoint any solvent can be
reclaimed to a point where it can be reused, for an alternative
use if not for its original purpose. The limiting factor deter-
mining whether a solvent is to be reclaimed is economic. The
cost of reclaiming a waste solvent may be higher than the cost of
the virgin material.
The process used to reclaim waste solvents has been termed "The
General Reclamation Scheme for Solvent Reuse." This process has
been broken down into the unit operations of storage and hand-
ling, initial treatment, distillation, purification, and waste
disposal. The total amount of solvent reclaimed by this process
is estimated to be 103.7 x 106 metric ton/yra.
Hydrocarbon and particulate emissions result from the reclaiming
of waste solvents. Noncriteria pollutants include any solvent
being reclaimed by a particular plant. Emission points from
plants reclaiming waste solvents are storage tank vents, con-
denser vents, incinerator stacks, and fugitive losses.
A representative plant was defined in order to determine the
severity of emissions from the solvent reclaiming industry.
Plant parameters used in determining a representative plant
include production capacity, population density, and emission
heights. These data were taken from information on the reclaim-
ing of waste solvents by private contractors.
al metric ton = 105 grams; conversion factors and metric system
prefixes are presented in the prefatory pages of this report.
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Parameters used to assess the impact of the solvent reclaiming
industry include source severity, state and national emission
contributions, and affected population.
Source severity has been defined as the maximum ground level con-
centration divided by a hazard factor. The ground level concen-
tration is determined by Gaussian plume methodology, and ambient
air quality standards are used to represent hazard factors for
criteria pollutants. Modified threshold limit values are used
to determine hazard factors for noncriteria pollutants. A repre-
sentative plant was found to have a hydrocarbon source severity
of 0.31 and a source severity for particulates of 0.0085. Using
selected solvents as noncriteria pollutants ranging from acetone
to butanol, source severities ranged from 0.0063 to 0.05.
Emissions from solvent reclaiming plants on a national scale
were found to total 218,000 metric ton/yr for hydrocarbons and
73,000 metric tons/yr for particulates. This accounts for 0.87%
and 0.41% respectively, of the total national emissions from
stationary sources.
Kentucky was the only state where hydrocarbon emissions from
reclaiming operations contributed greater than 0.01% of the
state's total hydrocarbon emissions. Solvent reclaiming opera-
tions contributed 0.001% or less of total particulate emissions
for any one state.
The area affected by a source severity of 0.1 from solvent
reclaiming operations has been calculated to be 0.12 km2. Pop-
ulation densities for plants of private contractors ranged from
24 persons/km2 to 2,223 persons/km2, with a mean value of 653
persons/km2. Thus the affected population for a representative
solvent reclaiming operation is 78 persons.
The rate of growth for private contractors reclaiming waste
solvents is a 5% annual increase in the amount of solvent re-
claimed. Using this percent increase, the total increase of
hydrocarbon emissions from 1977 through 1980 has been calculated
to be 0.03% or 59 metric tons.
Control equipment for hydrocarbon emissions includes floating
roofs, refrigeration, conservation vents for storage tanks,
packed scrubbers, and secondary condensers for distillation
units. Control of particulates from incinerator stacks is accom-
plished with wet scrubbers.
Fugitive emissions are a major source of emissions, comprising
at least 21% of the total hydrocarbon emission factor. Control
of fugitive emissions is accomplished by proper plant mainte-
nance, by improved loading procedures such as submerged filling,
and by reducing the number of solvent sources open to the
atmosphere.
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SECTION 3
SOURCE DESCRIPTION
The reclaiming of solvents is accomplished by industry as a main
process by private contractors, as an integral part of a main
process such as solvent refining, or as an add-on process seen
in the surface coating and cleaning industries. Table 1 (1-9)
identifies industries that reclaim solvents and the type and
(1) 1976 Refining Process Handbook. Hydrocarbon Processing,
55(9):189-230, 1976-
(2) Cantrell, A. Annual Refining Survey. The Oil and Gas
Journal, 74 (13):124-156, 1976.
(3) Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 18. John Wiley & Sons, Inc., New York, New
York, 1969. pp. 549-563.
(4) Formica, P. N. Controlled and Uncontrolled Emission Rates
and Applicable Limitations for Eighty Processes. Contract
68-02-1382, Task, 12, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, September 1976.
pp. V-43/V-46.
(5) Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 8. John Wiley & Sons, Inc., New York, New
York, 1965. pp. 796-797.
(6) Shreve, R. N. The Chemical Process Industries, Third Edition.
McGraw-Hill Book Company, Inc., New York, New York, 1969.
pp. 876-879.
(7) Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 14. John Wiley & Sons, Inc., New York, New
York, 1969. pp. 695-697.
(8) Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 7. John Wiley & Sons, Inc., New York, New
York, 1965. pp. 307-309.
(9) Scofield, F., J. Levin, G. Beeland, and T. Laird. Assessment
of Industrial Hazardous Waste Practices, Paint and Allied
Products Industry, Contract Solvent Reclaiming Operations,
and Factory Application of Coatings. EPA/530/SW-119c, U.S.
Environmental Protection Agency, Washington, B.C., September
1975. pp. 189-220.
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Ul
TABLE 1. DISTRIBUTION OF U.S. SOLVENT RECOVERED BY INDUSTRY
(103 metric tons/yr)
Vegetable
Solvent Polymerization oil Metallurgical
refining processes manufacture operations
Solvent (1, 2) (3, 4) (3, 5, 6) (3)
Halogenated hydrocarbons
Carbon tetrachloride
Fluorocarbons u
Methylene chloride
Perchloroethylene
Trichloroethylene
1 , 1 , 1-Tr ichloroethane
Hydrocarbons
b b
Hexane . -,
b b
Benzene -v
toluene
Xylene
Cyclohexane 73
Ethers
Mineral spirits .
Naphthas '
Ke tones
b
Acetone - -.
Methyl ethyl ketone -?
Methyl isobutyl ketone
Cyclohexanone
Alcohols
Methanol
Ethanol
Isopropanol
Butyl alcohol
Arayl alcohol
Esters
Amyl, butyl, ethyl acetates
b b
Others
c r c
TOTAL 92,000 250 9,100
Solvent
reclaimers
Pharmaceutical cleaning (private
manufacture operations contractors) Other
(3, 6, 7) . (3, 8) (9) industries
bh
L)
" c "b
1 QA
1|0 -b
"b "b
b
•"•
" D
~h
w
"b
~b
~b
\J
~b
~b
b
~b
L'
h "h
u u
~h
U
b b
~b
U
~b
b ~b
\J LI
~b
v
_b _b
b
V
c c
23 2,100 190
a
Blanks indicate data not available.
Particular solvent is reclaimed but quantity is unknown.
MRC estimates.
-------
amount of solvent recovered by each. Table 2 (1-4, 8-11) gives
the amount of solvent recovered by specific source and the number
of plants recovering solvent by industry. It is estimated that
these industries account for more than 80% of all solvent
recovered by industrial sources in the United States.
TABLE 2. SOLVENT RECLAMATION BY INDUSTRY3
Source
Number of
plants (2, 9-11)
Percent of
total plants
reclaiming solvents
Amount of solvent
reclaimed (1-4, 8) Weight
103 metric ton/yr percent
Solvent refining
Polymerization processes
Vegetable oil manufacture
Metallurgical operations
Pharmaceutical manufacture
Cleaning operations
Private contractors
43b
19b
240b
22?
20,160b
110b
0.21
0.09
1.2
0.11
97.89
0.5
92,000b
250D
9,100
V.
23°
2,100a
190a
88.8
0.2
8.8
0.02
2.0
0.18
TOTAL
20,594L
100
103,663
100
Blanks indicate data not available.
bMRC estimates.
In solvent refining, lube oils and waxes are prepared by solvent
extraction (1). After extraction, solvent is reclaimed and re-
used in the refining process. The manufacture of high-density
polyethylene and polypropylene utilizes solvents as chemical
mediums (3, 4). After polymerization, solvents are reclaimed
and recycled back to the polymerization process. Vegetable oil
manufacture, metallurgical operations, and pharmaceutical manu-
facture utilize solvents for extraction purposes and then reclaim
them for reuse in the main process (6, 12). Cleaning operations
include drycleaning and degreasing of metal (3). Private con-
tractors reclaim solvents from any industry that produces waste
solvents from solvent usage. The companies in this field can
differ greatly one from another, not only in the waste solvents
they process and resell, but also in their self-images. The
field is shared by such different companies as those who consider
themselves to be specialty chemical manufacturers and use waste
solvents as part of their raw material inputs; by companies who
only buy waste solvents for direct sale to others with or without
(10) 1972 Census of Manufacturers, Industry Series (SIC Industry
Group 207), Fats and Oils. MC72(2)-20G, U.S. Department of
Commerce, Washington, D.C., January 1975. 38 pp.
(11) Suprenant, K. S., and D- W. Richards. New Source Perform-
ance Study to Support Standards for Solvent Metal Cleaning
Operations, Appendix Reports (Appendix A). Contract
68-02-1329, U.S. Environmencal Protection Agency, Durham,
North Carolina, June 30, 1976. 87 pp.
(12) Clegg, J. W., and D. D. Foley. Uranium Ore Processing.
Addison-Wesley Publishing Company, Inc., Reading,
Massachusetts, 1958. 437 pp.
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processing; and by companies who process a variety of materials,
sell what is marketable, and handle their own final disposal
problems through incineration and landfill. Solvent use and re-
clamation by other operations such as the coating industry are
covered in Table 1 under "Other Industries."
The solvent reclaiming proce'ss is described by the unit opera-
tions shown in Figure 1, General Reclamation Scheme for Solvent
Reuse. All solvent recovery operations are included under this
prpcess description.
STORAGE FUGITIVE FUGITIVE
TANK VENT EMISSIONS EMISSIONS
CONDENSER FUGITIVE FUGITIVE
VENT EMISSIONS EMISSIONS
STORAGE FUGITIVE
TANK VENT EMISSIONS
WASTE
SOLVENTS
RECLAIMED
SOLVENT
INCINERATOR STACK
FUGITIVE EMISSIONS
Figure 1. General reclamation scheme for solvent reuse.
Methods employed in each unit operation are described in this
section. Criteria determining which methods are appropriate in
reclaiming a particular waste solvent are provided in the
description of each unit operation.
PROCESS DESCRIPTION
Solvent Storage and Handling
Solvents are stored before and after reclamation. For example,
private contractors reclaim .solvents from various industries such
as paint manufacturers and degreasing operations. The solvents
are transported from the industrial site, in tank cars and drums,
to the reclaiming plant, where they are recovered and then re-
turned to the site or sold to another plant for reuse. This pro-
cedure involves continuous storage and handling since solvent
must be loaded on and off tank cars and trucks and stored until
processing time is available.
Solvents are stored in containers ranging in size from 0.208 m3
(55-gal) drums to tanks with capacities of 75 m3 (20,000 gal) or
more. Storage tanks are of fixed or floating roof design.
Fixed-roof tanks are metal cylinders or boxes of rigid construc-
tion. Venting systems are used to prevent solvent vapors from
creating excessive pressure inside the tanks. Floating-roof
-------
tanks have movable tops which float on the surface of the con-
tained solvent while forming an airtight seal with the tank
walls (13).
The handling of solvent includes the loading of waste solvent :
into process equipment and the filling of drums and tanks prior
to transport and storage. Filling of tanks and drums is done .
through splash or subsurface loading (14). Splash loading is
the filling of the tank or drum from the top, allowing solvent
to fall free to the bottom of the container. Subsurface filling
is accomplished by pumping the solvent into the bottom of the
solvent container.
Initial Treatment
Waste solvents are initially treated by vapor recovery or mechan-
ical separation. Vapor recovery entails removal of solvent
vapors from a gas stream in preparation for further reclaiming
operations. In mechanical separation undissolved contaminants
such as metal fines are removed from liquid waste solvents.
The initial treatment method chosen depends upon the factors
listed in Table'3 (15).
TABLE 3. FACTORS DETERMINING THE SUITABILITY
.OF INITIAL TREATMENT METHODS (15) . -
Waste solvent vapor
solvent vapor composition
air concentration of gas stream
solvent boiling point
solvent reactivity
gas stream composition
solvent vapor concentration
solvent solubility
Liquid waste solvent
• solvent miscibility
• solids content of waste solvent
(13) Chemical Engineers' Handbook, Fifth Edition. J. H.'. Perry
and C. H. Chilton, eds. McGraw-Hill Book Company, New York,
New York, 1973.
(14) Wachter, R. A., T. R. Blackwood, and P. K. Chalekode. Sturdy
to Determine Need for Standards of Performance for New
Sources of Waste Solvents and Solvent Reclaiming. Contract
68^02-1411, Task 15, U.S. Environmental Protection Agency
Research Triangle Park, North Carolina, February 1977.
106 pp.
(15) Drew/ J. W. Design for solvent Recovery. Chemical
Engineering Progress, 71(2):92-99, 1975.
8
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Absorption, adsorption, and condensation are initial treatment
techniques used for collecting solvent vapors from gas streams
(16). The technique most suitable for recovering a particular
solvent vapor is determined by the factors listed in Table 3
under waste solvent vapor. Industries which make use of vapor
recovery systems include magnetic tape production and rubber
manufacture (17, 18).
Condensation of solvent vapors is accomplished by water-cooled
condensers and refrigeration units. Condensers are capable of
reaching temperatures of 15°C, while refrigeration units go as
low as 10°C (16). The feasibility of condensation for vapor re-
covery is dependent upon solvent concentration and the tempera-
ture required for condensation. For adequate recovery, solvent
components must be above the saturation concentration at the
condensing temperature. A solvent vapor concentration well above
20 mg/m3 is required for effective recovery of solvent vapors by
condensation (19) .
To avoid explosive mixtures of solvent and air in the process
gas stream, air is replaced with an inert ga;s such as nitrogen.
Solvent vapors which escape condensation are recycled through
the main process stream or recovered by further initial treatment
with adsorption or absorption.
Solvent vapors are also recovered by adsorption on activated car-
bon. Process gas streams are passed through a bed of activated
carbon where solvent vapors are adsorbed. When solvent concen-
trations in the carbon bed approach saturation level, the gas
stream is directed to a second bed, and the first bed is
regenerated with live steam. A vapor mixture of solvent and
steam is condensed and sent to further recovery processing (19).
Activated carbon adsorption systems are capable of recovering
solvent vapors in concentrations below 4 mg/m3 of air (19). If
solvent vapor concentrations are above 20 mg/m3 of air, pre-
liminary recovery of solvent by condensation is used to allow a
maximum amount of solvent-laden air to pass through the carbon
(16) Scheflan, L., and M. B. Jacobs. The Handbook of Solvents.
D. Van Nostrand Company, Inc., New York, New York, 1953.
728 pp.
(17) Solvent Recovery System Proves a Speedy Payout. Rubber
World, 165(5):44, 1972.
(18) Reynen, F., and'K.. L. Kunel. Solvent Recovery System Nets
Plant Approximately $50,000/yr Savings. Chemical Process-
ing 38(9):9, 1975.
(19) Darvin, R. L. Recovery and Reuse of Organic Ink Solvents.
C and I'Birdler, Inc., Louisville, Kentucky, September 1975.
25 pp.
-------
bed before desorption is necessary. Two factors that affect the
technical feasibility of recovering solvent vapors are the molec-
ular weight and boiling point of the solvent. Activated carbon-'
will not recover solvents having a molecular weight of less than
30 from air streams (20). Also, solvents with boiling points of
200°G or more do not desorb effectively from activated carbon
with low pressure steam (20).
Absorption of solvent vapors by a liquid medium provides an
alternative to adsorption schemes. The waste gas stream is
passed through a liquid by means of scrubbing towers or spray
chambers. Mineral oils have been used as absorbing liquids (16).
Solvent vapors from oil seed extraction processes have been
recovered by absorption (21).
The (-ffectiveness of solvent recovery by absorption is dependent
upon the solubility of the solvent vapor in the absorbing liquid.
Solubility is expressed in the form of an equilibrium constant
(K) which equals the mole fraction of the solvent in the gas
phase divided by the mole fraction of solvent in the liquid
phase. K will vary with changes in temperature, pressure and
composition of the solvent and absorbing liquid (13).
Further reclaiming procedures are required after solvent vapors
are collected by condensation, adsorption or absorption. Re-
covery of solvent by condensation and adsorption results in a
mixture of water and liquid solvent. Absorption recovery
results in a mixture of oil and solvent. Both mixtures are
ready for further reclaiming by distillation.
Distillation is not necessary if recovered solvent mixtures can
be reused without separation and the solvents are immiscible in
water (22). In this case solvent-water mixtures are sent
directly to purification where the water is removed and the sol-
vent is prepared for reuse (23).
(20) Enneking, J. C. Control Vapor Emissions by Adsorption.
Union Carbide Corporation, New York, New York, 1973. 6 pp.
(21) Oil Absorption System for Vent Solvent Recovery. Engineer-
ing Management, Inc., Park Ridge, Illinois. 1 p.
(22) Pickett, G. E., J. A. Jacomet, and L. J. Nowacki. Disposi-
tion of Organic Solvents Recovered in Carbon Adsorption
Systems in the Industrial Surface Coatings Industry. Con-
tract 68-01-3159, Task 5, U.S. Environmental Protection
Agency, Cincinnati, Ohio, December 1976. 43 pp.
(23) Solvent Loss by Evaporation Cut 95% by Recovery System.
Chemical Processing, 38(1):25, 1975.
10
-------
Undissolved solids and water are removed from liquid waste sol-
vents by initial treatment through mechanical separation. This
means of separating water from solvent is feasible if the solvent
is immiscible in water. Methods for mechanical separation
include decanting, filtering, draining, settling, and use of a
(centrifuge. Decanting is used to separate water from immiscible
solvent, while the other methods are used to remove undissolved
solids from the waste solvent. A simple cone tank used for
settling out solids from waste solvent is shown in Figure 2.
WASTE SOLVENT
I
VENT
SOLVENT
VALVE
SOLVENT TO DISTILLATION
SLUDGE
SLUDGE PUMP
Figure 2. Cone settling tank for removal
of undissolved solids from
waste solvent.
A combination of initial treatment methods may be necessary to
prepare a waste solvent for further processing. For example, a
contaminated liquid solvent is filtered to remove undissolved
solids and then decanted to remove water before distillation.
In another instance solvent vapors are recovered by adsorption
and the resulting liquid solvent is decanted to remove water
before separation of the solvent mixture by distillation.
11
-------
Distillation
After initial treatment, waste solvents are distilled to separate
solvent mixtures and to remove dissolved impurities (24). De-
tails of the distillation unit operation are shown in Figure 3.
Waste solvents are distilled by one of the five distillation
methods listed below (13):
• Simple batch distillation
• Simple continuous distillation
• Steam distillation
• Batch rectification
• Continuous rectification
I
SOLVENT VAPOR
WASTE SOLVENT ^
STEAM
'
EVAPOI
1
I REFLUX
SOLVENT I 1
VAPOR | i
JATIHM -. . . ^J Pf? A PTIHM ATlftM 1 ^HMT
n 1 !
f
1ENSATION
1
SLUDGE
DISTILLED SOLVENT
Figure 3. Distillation process for solvent reclaiming (9).
In simple batch distillation a quantity of waste solvent is
charged to the evaporator. After charging, vapors are contin-
uously removed and condensed. The resulting sludge or still
bottom is removed from the evaporator after solvent evaporation.
Simple continuous distillation is the same as batch distillation
except that solvent is continuously fed to the evaporator during
distillation, and still bottoms are continuously drawn off. In
steam distillation solvents are vaporized by direct contact with
steam which is injected into the evaporator. Batch, continuous,
and steam distillations follow path I of the distillation proc-
ess shown in Figure 3. These three methods are suitable for
separating solvents from their dissolved contaminants.
(24) Solvent Recovery and Pollution Control Using Industrial
Distillation-Equipment. No. FB-118, Hoffman Filtration
Systems, New York, New York, 1974. 32 pp.
12
-------
The separation of mixed solvents requires multiple simple distil-
lations or rectification. Batch and continuous rectification are
represented by path II in Figure 3. In batch rectification,
solvent vapors pass through a fractionating column where they
contact condensed solvent (reflux) entering at the top of the
column. Solvent not returned as reflux is drawn off as overhead
product. In continuous rectification, the waste solvent feed
enters continuously at an intermediate point in the column. The
more volatile solvents are drawn off at the top of the column
while higher boiling point solvents collect at the bottom.
Design criteria for evaporating vessels depend upon waste solvent
composition. Resinous or viscous contaminants can coat heat
transfer surfaces, resulting in a loss of evaporator efficiency.
Evaporators with heating coils exposed to waste solvent are only
suitable for solvents with less than 5% solids content (9). Two
evaporators that prevent contaminants from fouling heating sur-
faces are of the'scraped surface or thin-film design. In the
scraped-surface type, rotating scrapers keep contaminants from
adhering to the heated evaporator walls. For heat sensitive or
viscous materials thin-film evaporators are the most suitable
(25). With this design, solvent is forced into a thin film along
the heated evaporator walls by rotating blades. These blades
agitate the solvent while maintaining a small clearance from the
evaporator walls to prevent contaminant buildup on heating sur-
faces. Figure 4 shows a typical thin-film evaporator.
SCUWILC-SEfflU
{]} HEATING JACKET
(!) CYLINDRICAL EVAPORATOR
UALL
13) ROTO
(4) SEPARATOR SECTION WITH
FIXED STATIONARY BAFFLES
(5) CONNECTIONS FOR HEATING
MEDIUM
(A) FEED INLET
(8) EXIT FOR LIQUI
SO VAPOR EXIT
Sr.HFWTlC CROSS SFCTlOii
(1) HEATING JACKET
(2) CYLINDRICAL EVAPORATOR
MALL
(3) ROTOR
(a) BLADE TIP CLEARANCE
UID PRODUCT
Figure 4. Thin-film evaporator (25)
(25) Reay, W. H. Recent Advances in Thin-Film Evaporation. Luwa
(U.K.)Ltd., London, England (reprinted from The Industrial
Chemist, June 1963). 5 pp.
13
-------
Condensation of solvent vapors during distillation is accom-
plished by shell and tube or barometric condensers. The shell
and tube design consists of parallel tubes running through a
cylindrical shell. Condensation of solvent is accomplished by
the flow of cooling water through the tubes, which are in contact
with solvent vapors in the shell. This arrangement prevents the
mixing of reclaimed solvent and cooling water. In barometric
condensers vapor is condensed by rising against a rain of cooling
water (13). Condensation of vapor results in a mixture of sol-
vent and cooling water. A barometric condenser is pictured in
Figure 5 (26, 27).
CONDENSER WATER
SOLVENT VAPORS
BAROMETRIC-^
CONDENSERS
y JET STEAM
2nd STAGE
f
TO ATMOSPHERE
OR TO A
CONDENSER FOR
JET STEAM
BAROMETRIC LEG
Figure 5. Barometric condenser with steam ejector
for distillation (26, 27).
(26) Nelson, W. L. Petroleum Refinery Engineering, Fourth
Edition. McGraw-Hill Book Company, New York, New York, 1958
pp. 252-261.
(27) Nelson, W. L. Questions on Technology: Noncondensable
Gases Handled During Vacuum Distillation. The-Oil and Gas
Journal, 49:100, April 1951.
14
-------
Azeotropic solvent mixtures are separated during distillation by
the addition of a third solvent component. For example, the
addition of phenol to cyclohexane-benzene mixtures during distil-
lation causes the activity coefficients for cyclohexane to be
nearly twice as large as those for benzene (13). This factor
causes the volatility of cyclohexane to be nearly twice that of
benzene, allowing for their separation by distillation.
Operating conditions for distillation are dependent upon the
particular .waste solvent and its desired purity after reclama-
tion. Solvents with boiling points in the range of high flash
naphthas (155°C) are most effectively distilled under vacuum (24).
Its use reduces heating requirements since the solvent boiling
point is lowered by vacuum conditions in the evaporator. A
vacuum can be achieved by vacuum pumps or steam ejectors. Dis-
tillation rate must be carefully controlled if contaminants are
not to be carried over into the condenser. Temperature control
is also necessary since excessive heat can chemically alter the
original solvent composition. Purity requirements for the re-
claimed solvent will determine the number of distillations
needed, reflux ratios, and processing time.
Purification
After distillation, water is removed from solvent by decanting
or salting. Decanting is accomplished with immiscible solvent
and water which, when condensed, form separate liquid layers, one
or the other of which can be drawn off mechanically. Additional
cooling of the solvent-water mix before decanting increases the
separation of the two components by reducing their solubility.
In salting, solvent is passed through a calcium chloride bed
where water is removed by absorption.
During purification reclaimed solvents are stabilized if neces-
sary. Buffers are added to virgin solvents to insure that pH is
kept constant during use. Reclaiming the solvent may cause a
loss of buffering capacity. To renew it, special additives are
used during purification. The composition of these additives is
considered proprietary.
Waste Disposal
Waste materials separated from solvents during initial treatment
and distillation are disposed of by incineration, landfilling or
deep-well injection. The composition of the waste material will
vary depending on the original use of the solvent. Up to 50% of
waste material from the reclaiming process will be unreclaimed
solvent. Not distilling all of the solvent from the waste en-
ables it to remain in a viscous yet liquid form, facilitating
pumping and handling procedures. The following components are
present in the waste from solvent reclaiming:
15
-------
• oils • metal .fines
• greases • dissolved metals
• waxes • organics
• detergents • vegetable fibers
• pigments • resins
A chemical analysis of specific wastes is given in Table 4.
These samples were taken from a presurvey study of a private con-
tractor who reclaims waste solvents.
TABLE 4. ANALYSIS OF SLUDGE FROM SOLVENT RECLAIMING
BY PRIVATE CONTRACTORS3
Percent
unreclaimed Percent composition of selected elements
solvent Al Ba B Ca Cd Co Cr' Fe MCL Mn Na Pb Sb
43 1.1 2.0 0.02 0.29 0.003 0.03' 0.15 2.7 2.7 0.007 0.20 3.3 0.05 0.02 0.08 0.05 23 0.03 0.38 0.06 0.06
Data obtained from presurvey sampling.
Incinerators capable of burning liquid wastes are used to dispose
of waste from solvent reclaiming operations. Figure 6 (28) shows
such an incinerator design. It is estimated that 80% of the
waste from solvent reclaiming by private contractors is disposed
of in this manner (9).
AIR INLETS
( COMBUSTION CHAMBER / ! REACTION.TAIL PIPE
WASTE INLET- ' '
AUXILIARY
FUEL INLET
Figure 6. Incinerator for liquid waste disposal (28).
Wastes are also disposed of by landfill deposition. Drums con-
taining solvent reclaiming wastes are dumped into the landfill.
Waste not contained in drums can be applied directly to the site,
Deep-well injection is used to dispose of reclaiming wastes if
injection sites are available. Wastes are injected between im-
permeable geologic strata. Dilution of viscous wastes may be
necessary for pumping them to the desired strata level.
(28) Clausen, J. R., R. J. Johnson, and C. A. Zee. Destroying
Chemical Wastes in Commercial Scale Incinerators, Facility
Report No. 1. Contract 68-01-2966, U.S. Environmental Pro-
tection Agency, Washington, D.C., October 1976. 116 pp.
16
-------
Industrial operations are capable of reclaiming their waste
solvents without incorporating all unit operations shown in
Figure 1. If solvent reclamation is part of a main process,
storage and handling of solvent during recovery is avoided since
solvent is continuously reclaimed and fed back into the main
process directly through pipes and/or pumps. Initial treatment
is not necessary if liquid waste solvents contain no undissolved
contaminants. Distillation can be avoided if solvent vapors con-
sist of only one water immiscible solvent. These one-component
vapors are collected, liquefied, purified, and reused without
distillation. Examples are given in Figures 7 and 8. Figure 7
shows the reclaiming of hexane without the need for storage and
handling of solvent during recovery (3). Figure 8 shows the
reclaiming of single-component ink solvent vapors by carbon
adsorption without the need for distillation (19).
The unit operations described in this section (storage and hand-
ling, initial treatment, distillation, and purification) are shown
in Figure 9 (29). In this figure a typical solvent reclaiming
process is being operated by a private contractor. Figure 10
illustrates distillation and purification operations of a solvent
reclaiming system utilizing thermal fluid for evaporation (30, 31).
MATERIALS FLOW
A simple material balance for a plant reclaiming 5,000 metric
tons/yr of solvent is shown in Figure 11. The legend indicates
the percent of total hydrocarbons emitted by each process opera-
tion. These percentages were estimated from emission factors
shown in Section 4.
GEOGRAPHICAL DISTRIBUTION
The number of cleaning operations reclaiming waste solvents out-
number other solvent reclaiming operations by a factor of 40.
More than 80% of cleaning operations reclaiming waste solvents
are drycleaning plants whose geographical locations are popula-
tion sensitive (8). The remaining cleaning operations are metal
degreasing plants. Their distribution and the distribution of
(29) Brighton Solvent Reclaiming Systems. Bulletin No. RS-4,
Brighton Corporation, Cincinnati, Ohio. 6 pp.
(30) System Strips Solvents, Separates Solids Simultaneously.
Chemical Engineering, 83(25):93-94, 1976.
(31) Continuous Purification of Waste Solvents. Chemical Proc-
essing (London), 20(1):17, 1974.
17
-------
CO
FLAKES
O
8
SOLVENT
O
PUMP
EXTRACTOR
HEAT EXCHANGER -
SOLVENT VAPOR
D
WATER
CONDENSER
REFRIGERANT
SOLVENT
AIR VENT
_L
DECANTER
T
WATER
n-J
~
DRYER
rJ— 1—
5 1 tMIVl
^
•*-
DESOLVENTI ZED FLAKES
1 — 1 m~
OIL PLUS
SOLVENT
STEAM
STEAM
WATER
CONDENSER
SOLVENT
"VAPOR
EVAPORATOR
STEAM
STEAM
STEAM
WATER
i *
1 11
OIL
Figure 7. Reclaiming of solvent from vegetable oil extraction with
direct feedback to main process (3).
-------
COOL ING WATER IN
WATER OUT
DRYER
CONDENSER
DECANTER
Figure 8. Reclaiming of single-component ink
solvent without distillation (19).
-------
LEVEL CONTROL
WASTE SOLVENT
LOADING AREA
Figure 9. Solvent reclaiming process used by a private contractor (29).
-------
r~
LEGEND
...... CLEAN SOLVENT
--- SLUDGE
---- THERMAL FLU ID
--- VACUUM
WATER
VACUUM
soivetfl..
:'.'-i-. SOLVENT VAPORS
WASTE SOLVENT
I
»STE
VENT
»
&
SOLVENT I
METERING !
VALVE 1
1
THERMAL aU ID !
CIRCULATION r^\
PUMP LIT"
L
LIQUID-RING
VACUUM PUMP
-CLEAN SOLVENT
COOLING WATER OUT
RUPTURE DISK
PUMP SEALING LIQUID
COOLING .WATER IN
// SUMP
_ SLUDGE VALVE
1 CAROUSEL
ewe-
1 RESERVOIR
FILTER BAGS
(1) THERMAL FLUID HEATING UNIT
( 2) EVAPORATOR
( 3 ) WASTE SOLVENT STORAGE TANK
(4) CONDENSER
( 5 ) VACUUM PUMP
(6) COOLING UNIT
(7 ) DECANTER
( 8 ) RECLAIMED SOLVENT
Figure 10.
Process schematic and equipment diagram
of a solvent recovery unit (30, 31).
21
-------
STEAM
1, 136 n
AIR EMISSIONS AIR EMISSIONS
WASTE
ron/rf!iT STORAGEAND SOLVENT INITIAL 4, 500 metric tons / yr
10 5, 000 Metric tons /yr HANDUNG TREATMENT 'WASTE SOLVENT '
N)
TOTAL HYDROCARBONS EMITTED BY PROCESS OPERATIONS
IN A 5,000 METRIC TOWS/YR SOLVENT RECLAIMING PLANT
Hydrocarbons'
Operation emitted, %
Storage and handling 0.3
Distillation 77.8
letric tons/
STEAM
yr 1
AIR
EMISSIONS
8. 25 kg 7 yr
SOLVENT
t
- DISTILLATION
WASTE SLUDGE
250 metric tons / yr SOLVENT
i 250 metric tons / yr CONTAMINANTS
WASTE DISPOSAL
( INCINERATION)
Incineration 0 . 5
Storage and handling i
Initial treatment I Fugitive emissions 21.4
Purification >
136 metric tons / yr
AIR EMISSIONS
WATER "
?nf) mfltrtr trine / vr ^
2, 250 metric tons / yr RECLAIMED SOLVENT
•" PUKIHoAt [UN »•
WASTE SOLVENT 2, 050 metric tons / yr
WASTE SLUDGE
. 1, 250 metric tons / yr SOLVENT
1,000 metric tons /yr CONTAMINANTS
AIR EMISSIONS
*~ 27.5 kg / yr HYDROCARBONS
1,980 kg /yr PARTI CULATES
Figure 11. Material balance for the reclaiming of waste solvents.
-------
NJ
U)
PERCENT OF TOTAL
PLANTS PER STATE
Figure 12. Geographical distribution of solvent reclaiming
operations in the United States (2, 9-11, 32).
-------
the other industries given in Table 1 are shown in Figure 12
(2, 9-11, 32). The number of sites in this category, which
excludes drycleaning operations, is estimated to be 4,158 plants
(2, 9-11, 32). Table 5 gives the estimated number of plants in
each state.
TABLE 5. STATE DISTRIBUTION OF SOLVENT RECLAIMING
OPERATIONS (2, 9-11, 32)
State
Alabama
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Number
of plants
72
37
39
424
44
60
12
141
98
14
224
113
59
49
70
83
19
83
85
178
76
45
98
15
Percent
of total
1.8
0.94
0.99
10.
0.16
1.5
0.35
3.5
2.4
0.4
5.5
2.8
1.4
1.2
1.7
2.0
0.5
2.0
2.0
4.3
1.8
1.1
2.3
0.41
State
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
TOTAL
Number
of plants
30
10
13
153
21
372
105
13
213
56
40
245
21
55
13
83
242
21
8
97
72
41
90
6
4,158
Percent
of total
0.77
0.29
0.38
3.7
0.57
8.9
2.5
0.37
5.1
1.3
1.1
5.9
0.57
1.3
0.36
2.0
5.8
0.56
0.24
2.3
1.7
0.99
2.2
0.14
100
(32) Marn, P. J., T. J. Hoogheem, D. A. Horn, and T. W. Hughes.
Source Assessment: Solvent Evaporation - Degreasing. Con-
tract 68-02-1874, U.S. Environmental Protection Agency,
Cincinnati, Ohio. (Final document submitted to the EPA- by
Monsanto Research Corporation, January 1977.) 180 pp.
24
-------
SECTION 4
EMISSIONS
Air emissions from a typical solvent reclaiming operation are
described in this section. Criteria pollutants emitted from.
solvent reclaiming operations include hydrocarbons and partic-
ulates. Emissions and their locations were shown earlier in
Figure 1. Emissions from solvent storage, distillation, and
waste disposal are discussed, and possible fugitive emission
points in the solvent reclaiming process are described.
\
SELECTED POLLUTANTS
Solvent Storage
The storage of solvents results in hydrocarbon emissions from
solvent evaporation. Fixed-roof storage tanks are equipped with
vents that emit hydrocarbon vapors during solvent storage. Since
tanks are continually in use during processing, solvent storage
is considered a continuous source of emissions.
Distillation
The venting of gases from distillation units occurs during con-
densation of solvent vapors. When steam ejectors are used to
produce a vacuum in the distillation unit, condensers emit steam,
noncondensables, and solvent vapors. The use of pumps for vacuum
conditions causes condensers to emit solvent vapors and noncon-
densables. Hydrocarbons emitted from condensers are a continuous
source of emissions.
Waste Disposal
The combustion of still bottom wastes results in emissions from
the incinerator stack. Solid contaminants in the sludge are
oxidized and released as particulates along with combustion
gases. Unburned hydrocarbons are also emitted with combustion
stack gases. Particulates and hydrocarbons from incinerators
are a continuous source of emissions.
Fugitive Emissions
Emissions from solvent loading, equipment leaks, solvent spills
and open solvent sources are classified as fugitive emissions.
25
-------
Hydrocarbon emissions from solvent loading and spills are inter-
mittent, while emissions from equipment leaks and open solvent
sources are continuous.
When solvent is agitated during loading procedures, it is atom-
ized into droplets which quickly evaporate and are emitted as
solvent vapors. Loading of fixed-roof tanks causes displacement
of the vapor space inside the tank by fresh solvent. This vapor
space contains solvent vapors evaporated during storage which
are then emitted to the atmosphere as hydrocarbon emissions.
Accidental spillage of solvent durina loading procedures also
results in hydrocarbon emissions from, solvent evaporation, as do
process equipment leaks.
i
Other sources of hydrocarbon emissions include open containers of
solvents and sludges. Settling tanks with open tops emit solvent
vapors during settling and sludge draw-off. During startup of
the distillation process an initial amount of distilled solvent
may be drawn off in an open drum to remove residual contamination
in the distillation equipment. This procedure constitutes an
intermittent source of hydrocarbon emissions. Open sources of
fugitive emissions include sludge draw-off and storage from dis-
tillation and initial treatment operations. Fugitive solvent
emissions can result from all of the unit operations described in
Section 3.
-------
TABLE 6. EMISSION FACTORS FOR SOLVENT RECLAIMING9
Source
Criteria
pollutant
Emission factor Emission factor
range, average,
,g/kg g/kg
Storage tank ventc
Condenser vent
Incinerator stack
Fugitive emissions
Spillage
Loading
Leaks
Open sources
TOTAL
TOTAL
Hydrocarbons
Hydrocarbons
Hydrocarbons
Particulates
0.002 to 0.004 0.0072 ± 0.0038
0.26 to 4.17 1.65 ± 1.38
0.01C 0.01C
0.55 to 1.0 0.72 ± 0.61
Hydrocarbons rj o.095
Hydrocarbons ; 0.00012 to 0.71
Hydrocarbons
Hydrocarbons
Hydrocarbons-
Particulates
0.38 to 5.0
0.55 to 1.0
0.095
0.36 ± 0.24
2.1
0.72
Data obtained from state air pollution control agencies and pre-
survey sampling. All emission factors are for uncontrolled process
equipment except those for the incinerator, stack. Blanks indicate
data not available. '-»
3 ' . '- > O '•
Storage tank is of the fixed-roof des.ign.
"*
"Only one value available. ;
TABLE 7. CONTRIBUTION OF CRITERIA POLLUTANTS
FROM SOLVENT RECLAIMING TO NATIONAL
STATIONARY SOURCE EMISSIONS3
Criteria
pollutant
Hydrocarbons
Particulates
Total national
emissions (33) ,
metric tons/yr
25 x 106
18 x 106
«,
Emissions from
solvent reclaiming,
metric tons/yr
218,000
73,000
Percent of
national
emissions
0.87
0.41
Data derived from material balance.
27
-------
TABLE 8. SOLVENT RECLAIMING CONTRIBUTIONS TO STATE
EMISSIONS OF CRITERIA POLLUTANTS9
00
State
Alabama
California
Connecticut
Florida
Georgia
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
New Jersey
New York
North Carolina
Ohio
Oklahoma
Oregon
Pennsylvania
South Carolina
Tennessee
Texas
Virginia
Washington
Wisconsin
State
emissions,
10 metric tons/yr
643.4
2,161
219.7
619.9
458
1,826
600.5
316.6
309.6
26.3
1,920
295.9
440.5
717.9
1,761
196
413.1
819.5
1,262
447.2
1,153
341.3
234.7
891.8
907.8
362.9
2,219
369.4
344.6
523.9
Hydrocarbons
Emissions from
solvent reclaiming,
metric tons/yr
3.9
21.8
3.3
7.6
5.2
12.0
6.1
3.0
2.6
3.7
4.3
4.3
4.3
9.3
3.9
2.4
5.0
8.1
19
5.4
11.0
2.8
2.4
13
2.8
4.3
13
5.0
3.7
4.8
Particulates
Percent of
. state
emissions
0.0006
0.001
0.0015
0.0012
0.0011
0.0007
0.0001
0.0094
0.0008
0.014
0.0002
0.0015
0.001
0.0013
0.0002
0.0012
0.0012
0.001
0.0015
0.0012
0.0009
0.0008
0.001
0.0015
0.0003
0.0012
0.0006
0.0013
0.001
0.0009
State
emissions,
10 3 metric tons/yr
1,179
1,010
40.07
226.5
404.6
1,143
748.4
216.5
348.3
546.2
380.6
494.9
96.16
705.9
266
168,. 3
202.4
151.8
160
481
1,766
93.6
169.4
1,811
198.8
409.7
549.4
477.5
161.9
411.6
Emissions from
solvent reclaiming,
metric tons/yr
1.3
7.5
1.1
2.6
1.8
4.1
2.1
1.0
0.89
1.3
1.5
1.5
1.5
3.2
1.3
0.82
1.7
2.8
6.6
1.9
3.8
0.97
0.82
4.4
0.97
1.5
4.3
1.7
1.3
1.6
Percent of
state
emissions
0.0001
0.0007
0.0027
0.0011
0.0044
0.0003
0.0003
0.0005
0.0002
0.0002
0.0004
0.0003
0.0015
0.0005
0.0004
0. 0005
0.0008
0.002
0.0041
0.0004
0.0002
0.001
0.0005
0.0002
0.0005
0.0003
0.0008
0.0003
0.0008
0.0004
aStates where solvent reclaiming operations , comprise £1.0% of the total number of known reclaiming operations are not
considered.
-------
DEFINITION OF A REPRESENTATIVE SOURCE
A representative plant reclaiming waste solvents is defined in
order to determine source severity. The population density for
a representative plant was determined from data on the locations
of private contractors reclaiming waste solvents. Population
data for 30 randomly selected plants are given in Table 9.
Production capacity for a representative plant was determined
TABLE 9. POPULATION DENSITIES FOR RANDOMLY SELECTED
PLANTS RECLAIMING WASTE SOLVENTS9
Plant
Location
Population density,
persons/km2
Dyna-Clean Labs
Kho-Chem
Davis Chemical
Solvent Distilling Service
Solvent Recovery Service
Ansec Chemical
Rho-Chemical
Midwest Solvent Recovery
American Chemical Services
Hammond Solvent Recovery Service
Galaxy Chemicals
Silvesim Chemical
Gold Shield Solvents
Chemical Recovery Systems
Clayton Chemicals
Marisol '
C.P.S.
Frontier... Chemical Waste Processing
Hukill Chemical
Systech Waste Treatment
Jones Chemical Reclaiming
Jadco
Mid-State Solvent Recovery
Nuclear Sources and Services
Western Processing
North Central Chemical
Romie Chemical
Custom Organics
Perk Chemical
Chemical Recycling
Phoenix, AR
Inglewood, CA
Los Angeles, CA
San Jose, CA
Southington, CT
Douglasville, GA
Joliet, IL
Chicago, IL
Griffith, IN
Hammond, IN
Elkton, MD
Lowell, MA
Detroit, MI
Romulus, MI
St. Louis, MO
Middlesex, NJ
Old Bridge, NJ
Niagara Falls, NY
Cleveland, OH
Franklin, OH
Erie, PA
Greenville, SC
LeVerque, TN
Houston, TX
Seattle, WA
Madison, WI
Palo Alto, CA
Chicago, IL
Elizabeth, NJ
Wyllie, TX
Mean value (95% confidence limit)
40.8
668.1
668.1
316.7
426.7
54.8
23.7
2,223.5
411.1
411.1
56.8
654.0
1,704.2
1,704.2
736.4
722.5
722.5
171.1
1,457.1
31.4
126.8
117.4
25.2
390.3
210.4
93.5
565.3
2,223.5
2,036.0
596.8
653 + 212.6
Thirty private contractor sites were selected at random in order to deter-
mine mean population.
29
-------
by taking the total amount of solvent reclaimed by private con-
tractors averaged over the number of sites. Emission height data
available from plant visits and presurvey sampling of private
contractors are shown in Table 10.
TABLE 10. EMISSION HEIGHT DATA FOR PRIVATE CONTRACTORS
RECLAIMING WASTE SOLVENTS
Emission point Height, m
Storage tank vent 9.1
3.7
12.2
12.2
12.2
12.2
9.1
9.1
7.3
7.3
7.9
7.9
mean (95% confidence limit) 9.2 + 1.6
Condenser vent 5.5
7.6
6.1
3.7
9.1
mean (95% confidence limit) 6.4 + 2.6
Incinerator stack 18.3 18.3a~
Fugitive emissions 2.4 2.4a
Only one numerical value available.
Emission factors from Table 6 were used for a representative
plant. Table li summarizes the data for a representative plant,
ENVIRONMENTAL EFFECTS
Maximum Ground Level Concentration
The maximum ground level concentration, Xmax, for materials
emitted by solvent reclamation was estimated by Gaussian plume
dispersion theory.
Time-Averaged Maximum Ground Level Concentration
The maximum ground level concentration averaged over a given
period of time, Xmax, is calculated from Xmax by the following
equation:
30
'
-------
TABLE 11. SUMMARY OF DATA FOR A REPRESENTATIVE PLANT
Value for
Parameter representative plant
Process Solvent reclaiming
Raw material Waste solvent
Population density, persons/km2 653 ± 33%
Production capacity,-metric tons/yr 1,737 ± 30%
Emission heights, m
Storage tank vent 9.2 ± 17%
Condenser vent 6.4 ± 41%
Incinerator stack 18.3
Fugitive emissions 2.4
Emission factor, g/kg
Storage tank vent 0.0072 ± 53%
Condenser vent 1.65 + 84%
Incinerator stack
Particulates 0.72 ± 84%
Hydrocarbons 0.01
Fugitive emissions 0.455
X" = X I r2 ) (1)
max max \ t /
where t = averaging time, min
t = short-term averaging time, <3 min
The averaging times for particulates and hydrocarbons are 24 hr
and 3 hr, respectively.
Source Severity
The hazard potential of solvent reclaiming operations can be
quantified by determining a source severity, S, which is defined
as the ratio of the time-averaged maximum ground level concentra-
tion to F, the hazard exposure level for a pollutant. Since only
criteria pollutants are being considered at this point, the
primary ambient air quality standards for hydrocarbons and par-
ticulates represent the hazard exposure level, F. The source
severity is thus calculated in the following manner:
s = L (2)
Table 12 gives the emission rate, maximum ground level concentra-
tion, time-averaged maximum ground level concentration and source
severity of the emission points described in this section for a
representative solvent reclaiming plant.
31
-------
TABLE 12. EMISSION RATE,
XT
AND SOURCE SEVERITY
J_*J.J. J~ fcj LJ JLWI.N XxTlX JLJ f X /A •T1.JLV1-' t_J W WiX^A-l (-*J-J v JUi *•**«. J
FOR EMISSIONS FR8$XA R§ffelSENTATIVE SOLVENT
RECLAIMING PLANT
Emission rate,
Emission point g/s
Storage tank vent
Condenser
Incinerator stack
Particulates
Hydrocarbons
Fugitive emissions
0.
0.
0.
0.
0.
0004
09
04
0005
03
2.
1.
6.
7.
2.
Xmax ' Xnu
g/m3 g/i
5
1
3
8
7
x
x
X
X
X
ID'7
10-"
10~6
10- 8
10-"
1.2
5.5
2.2
3.9
1.3
x
X
X
X
X
*$'
n3 Source severity
10- 7
ID'5
10"6
10"8
10-"
0
0
0
0
0
.00075
.34
.0085
.00024
.84
The source severity for total hydrocarbons emitted by a represen-
tative solvent reclaiming plant has been calculated. A mean
emission height of 8-6 ±1.8 m was used with a total hydrocarbon
emission rate of 0.12 g/s. Table 13 gives the results of this
calculation.
TABLE 13. SOURCE SEVERITY FOR TOTAL HYDROCARBONS EMITTED FROM A
REPRESENTATIVE PLANT (UNCONTROLLED EMISSIONS)
Emission
Emission
g/s
rate ,
Xmax'
g/m~
Xmax '
g/m3
Source
severity
Hydrocarbons
0.12
1.0 x 10-'
5."0 x 10
-5
0.31
Table 14 lists threshold limit values (TLV®) (34) for commonly
reclaimed solvents. Source severities for selected solvents
are shown in Table 15.
Affected Population
The population affected by a solvent reclaiming operation is
determined from representative plant data. Since no source
severity greater than 1.0 was determined, the population affected
by a source severity greater than 0^_1 was .utilized. Table 16
gives the affected population whenx/F > 0-1 over an area of
0.12 km2. This affected population was obtained by calculating
the area within the isopleth for x
ITLclX
(34) TLVs® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1976. American Conference of Governmental
Industrial Hygienists, Cincinnati, Ohio, 1976. 97 pp.
32
-------
TABLE 14. THRESHOLD LIMIT VALUES
FOR SELECTED SOLVENTS
Solvent
Acetone
Amyl acetate
Benzene
Butanol
Cyclohexane
Ethyl acetate
Ethanol
Hexane
Isopropanol
Methyl ethyl ketone
Methyl isobutyl ketone
Methylene chloride
Perchloroethylene
Toluene
1,1,1-Trichloroethane
Trichloroethylene
Xylene
TLV,
mg/m3
2,400
650
80
300
1,050
1,400
1,900
1,800
980
590
410
360
670
375
1,900
535
435
TABLE 15. SOURCE SEVERITY FOR SELECTED SOLVENTS'
Solvent
Acetone
Isopropanol
Methyl ethyl ketone
Toluene
Butanol
TLV,
g/m3
2.4
0.98
0.59
0.37
0.3
Xmax'
g/m 3
5.0 x 10-5
5.0 x 10~5
5.0 x 10~5
5.0 x 10~5
5.0 x 10~5
Source severity
0.0063
0.015
0.026
0.042
0.05
Data for emission rate,
Table 12.
xmax' and xmax were taken from
TABLE 16. AFFECTED POPULATION FOR A REPRESENTATIVE
PLANT (UNCONTROLLED EMISSIONS)
Parameter
Value for
representative plant
Population density, persons/km2
Emission height, m
Emission rate, g/s
Pollutant type
Source severity
Affected area, km2
Affected population, persons
653
8.6
0.12
hydrocarbons
0.31
0.12
78
33
-------
SECTION 5
CONTROL TECHNOLOGY
STATE OF THE ART
Solvent reclamation is viewed by industry as a form of control
technology in itself. For industries where hydrocarbons are
emitted, such as in ink printing operations;^'reclaiming of sol-
vent vapors provides a means of emission control while recovering
a valuable production material (19). In this case the cost of
control technology is defrayed by the value of recovered solvent.
Reclamation of liquid waste solvents is also a form of control
technology since their disposal rather than reuse would cause
additional emissions to the atmosphere.
Control technology is described below for three areas of solvent
reclaiming operations: storage and handling, distillation, and
waste disposal. The number of plants that employ control tech-
nology is not known. Estimates have been given that less than
50% of the plants run by private contractors utilize control
technology (9) .
,')
Hydrocarbon emissions from the storage of solvents are reduced
by improved storage tank design. Floating-roof tanks emit 94%
to 98% less hydrocarbons by weight, as compared to fixed-roof
designs, by reducing the available surface area of stored solvent
exposed to air and by eliminating vapor space between the solvent
surface and storage tank roof (35) . Reduction of hydrocarbon
emissions by a floating-roof tank is dependent upon solvent evap-
oration rate, ambient temperature, loading rate, and tank
capacity.
Control technology may be added to fixed-roof tanks to reduce
hydrocarbon emissions from stored solvents. Tanks are refrig-
erated to reduce emissions by decreasing the evaporation rate of
the stored solvent. Conservation vents are also used to control
emissions from stored solvent. These vents are equipped with
breather valves designed to prevent either the inflow of air or
the escape of vapors from the tank until some preset vacuum or
(35) Manual on Disposal of Refinery Wastes, Volume on Atmospheric
Emissions. American Petroleum Institute, Washington, D.C.,
February 1976. pp. 7-1 through 7-14.
34
-------
pressure develops (36). This system prevents stored solvent
from contact with the atmosphere unless the tank is being filled
or drained of solvent.
Submerged filling of storage tanks and tank cars, rather than
splash filling, can reduce solvent emissions by more than half
(35). Submerged filling minimizes agitation and atomization of
liquid solvent when it is pumped into the tank.
Proper plant maintenance and loading procedures reduce solvent
emissions from leaks and spills. Fugitive emissions from process
equipment leaks pose a problem not only as air pollutants but
also as a safety hazard, especially'when reclaiming flammable
solvents. Leaks can be controlled by replacing worn-out equip-
ment and performing, regular .maintenance procedures. Careful
loading procedures can , seduce the number of solvent spills and
consequent emissions ' f row ..spilled solvent evaporation.
-!• ,-• . I "*• >~
Solvent vapors vented during distillation?are controlled by
scrubbers and additional condensers. A countercurrent packed
scrubber has been used to control vent gases from solvent dis-
tillation. In this type of unit vent gases enter from the bottom
and travel up through the scrubber, which is filled with packing
material. An absorbing liquid enters the scrubber from the top
and passes through concurrently to the flow of vent gases..;,, Con-
tact between absorbing liquid and vent gases occurs in the packed
section of the scrubber. Gases not absorbed by the liquid are
released to the atmosphere from the top of the scrubber. One
private contractor reclaiming waste solvents reported a 99% con-
trol efficiency for a gas scrubber installed in line with
condenser vents. In Figure 13, a packed scrubber is shown (37).
6AS OUTLET
MIST ELIMINATOR
SECTION
PflCKED SCRUBBING
SECTION
GAS INLET
LIQUID INLET
S'.-I I J1
LIQUID OUTLET
Figure 13. Typical countercurrent vent gas scrubber (37).
(36) Evaporation Loss in the Petroleum Industry - Causes and
Control. Bulletin No. 25B, American Petroleum Institute,
Washington, D.C., 1959. 59 pp. r-;-
(37) Liptak, B. G. Environmental Engineer's Handbook, Vol. 2.
Chilton Book Company, Radnor, Pennsylvania, 1974. 1340 pp.
35
-------
Solvent vapors vented by the condenser during distillation are
also reduced by addition of a secondary condenser in series with
the first. Vent gases are condensed in the secondary condenser
to yield distilled solvent which had passed through the primary
condenser.
Afterburners can be used to control noncondensables and solvent
vapors not condensed during distillation. Two types of after-
burners used to control solvent vapors are direct flame and
catalytic. The time necessary for complete combustion of solvent
vapors by an afterburner will depend on the flammability of the
solvent. For most solvents 0.3 s to 0.6 s at 1,193°C to 1,306°C
is required for effective control of vent gases (38). Condenser
emissions have also, been controlled with the afterburner prin-
ciple by venting gases to a boiler firebox where they are
combusted (39).
Control of vent gases in the manufacture of vegetable oils has
been accomplished by refrigerated condenser vents or the addi-
tion of vapor control devices utilizing carbon adsorption or oil
adsorption (40).
In wet scrubbers, which are used to remove particulates from
incinerator exhaust gases, gas flow is constricted by a venturi
throat where water is atomized to remove particulates by impac-
tion. Submicron particulates are not effectively controlled by
wet scrubbers. One plant reclaiming wastes solvents reported
metal oxide emissions from their incinerator stack after gas
stream scrubbing (9).
Source severity for a representative plant with control equip-
ment is shown in Table 17.
(38) Control Techniques for Hydrocarbon and Organic Solvent
Emissions from Stationary Sources. National Air Pollution
Control Administration Publication No. AP-68, U.S. Depart-
ment of Health, Education, and Welfare, Washington, D.C.,
March 1970. 1-1 to 7-3 pp.
(39) Air Pollution Engineering Manual, Second Edition, J. A.
Danielson, ed. Publication No. AP-40, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina,
May 1973. 987 pp.
(40) Background Information for Establishment of National Stand-
ards of Performance for New Sources, Vegetable Oil Industry
(Draft). Contract CPA 70-142, Task 9h, U.S. Environmental
Protection Agency, Raleigh, North Carolina, July 1971. 64 pp.
36
-------
TABLE 17. SOURCE SEVERITIES FOR RECLAIMING PLANTS
WITH AND WITHOUT CONTROL EQUIPMENT9
Source u
Control equipment used severity
None 0.31
Floating-roof storage tanks 0.23
Vent gas scrubber 0.12
Floating-roof storage tank and vent gas scrubber 0.082
Submerged loading 0.22
Data from a representative plant and control equipment
efficiencies were used to calculate source severity.
All source severities refer to total hydrocarbons emitted
from a representative plant. Calculation of these source
severities is the same as that used in Table 13. Values
shown represent the source severity for total hydrocarbons
when various control equipment is utilized. Values should
not be compared with source severities in Table 12 as they
are for specific uncontrolled emission points at various
heights.
FUTURE CONSIDERATIONS
Due to the increase in the price of virgin solvent, industry will
strive for increased efficiencies when reclaiming solvents (9).
Operations reclaiming up to 4.5 x 106 metric ton/yr of solvent
must achieve recovery efficiencies of greater than 90% if capital
losses from solvent consumption are to be avoided (3). Improved
efficiency of recovery operations stimulated by the higher costs
of solvents will serve as a means of emission reduction'. Also,
federal, state, and local emission standards for hydrocarbons
are becoming increasingly stringent (41).
The cost of disposal for waste from solvent reclaiming has more
than doubled in the past 5 years. This has been caused by the
increasing scarcity of acceptable landfill sites and the imposi-
tion of emission regulations on the disposal of liquid wastes by
incineration. As an alternative to disposal, new applications
for reclaimed solvent wastes are being tried. One application is
the use of reclaiming wastes as asphalt extenders and concrete
block fillers (9) . At a paint manufacturing plant, wastes
from spent solvent reclamation are reused in the main paint
production process (42).
(41) Teale, J. M. Fast Payout From In-Plant Recovery of Spent
Solvents. Chemical Engineering, 84 (3) :98-100, 1977.
(42) Emmerling, J. Economical Recovery of Waste Solvent Pro-
vided by System. Chemical Processing, 38(4):22-24, 1975.
37
-------
SECTION 6
GROWTH AND NATURE OF THE INDUSTRY
PRESENT TECHNOLOGY
Technology for the reclaiming of waste solvents is well estab-
lished (9). The operations described in this document will con-
tinue to be used for all aspects of solvent reclaiming.
EMERGING TECHNOLOGY
Though solvent reclaiming technology is well established,
collection of waste solvent vapors and liquids is not always
economically or technically feasible. Established plants emit-
ting waste solvents were not designed with vapor collection in
mind. These plants find that the cost of installing present-day
venting systems is prohibitive or that the systems are not cap-
able of collecting a major portion of the solvent vapors emitted.
New plants where waste solvents are produced from solvent usage
will be designed with solvent collection and reclamation as part
of the main process. Small plants using only 500 kg/day of sol-
vent find on-site solvent reclamation uneconomical in terms of
manpower and equipment needs. Recent engineering estimates,
however, have shown that small on-site reclaiming systems can
cover installation and operating costs through the value of the.
reclaimed solvent (41).
Design parameters and economic factors are considered in deter-
mining whether an on-site reclaiming system is a worthwhile
venture for a particular plant. The size of the distillation
unit, steam requirements, and manpower needs can be calculated
from the type and amount of solvent used during plant operation.
Knowledge of the physical and chemical properties of contaminants
which are removed from the waste solvent during reclamation is
also important. Design of the distillation unit, cost of mate-
rials on its construction, and percentage of solvent recovered
are determined by the extent and characterization of contamina-
tion present in the waste solvent. These considerations will
influence the decision as to whether a waste solvent is more
economically reclaimed on site, recovered by a private contractor
or simply disposed of by landfilling or incineration.
Waste solvents reclaimed from a paint manufacturing operation
results in highly corrosive and viscous stillbottoms. Corrosive-
resistant materials must be employed in the construction of the
38
-------
distillation apparatus to insure a reasonable period of use from
the equipment. The percentage of solvent recovered from the
waste solvent is about 40% to 50%. If more solvent was distilled
off, the stillbottoms would present an additional handling and
disposal problem due to their increasingly high viscosity.
At a printing operation, however, 80% of the waste solvent can
be recovered with a distillation unit of lower material stand-
ards. Ink contaminants are less corrosive to materials used in
the distillation apparatus. Recovery of a greater percentage of
solvent is also possible since the resulting stillbottoms are
less viscous than those produced from the reclamation of solvents
used in paint manufacturing.
When investigating the feasibility of on-site solvent reclamation
by a particular plant, reviewing alternatives based on economy
is necessary. Differences in the cost of virgin solvent utili-
zation, waste solvent disposal, private contractor reclamation,
and on-site reclamation become important criteria in determining
the practicality of any solvent reuse scheme.
INDUSTRY PRODUCTION TRENDS
Growth rates for solvent reclaiming operations depend upon the
rate of growth of solvent usage. In industries such as solvent
refining and vegetable oil extraction, where solvent recovery
is well established, the growth of solvent reclaiming will fol-
low the growth of the industry itself. For industries such as
coating applications and degreasing operations, where solvent
recovery is not consistent throughout all plants, the growth of
solvent reclamation will be governed by solvent availability and
cost. A growth rate for private contractors has been estimated
at a 5% increase annually in the amount of solvent reclaimed (9).
It is expected that the growth of solvent reclaiming operations
will follow the growth of future solvent usage. Table 18 gives
expected growth rates for solvent usage through 1980 (14).
TABLE 18. GROWTH RATES FOR SELECTED SOLVENTS (14)
(Percent)
Solvent
Ketones
Esters
Glycol-ethers
Amyl, butyl, ethyl and
isopropyl alcohols
Methyl chloride
Methylene chloride
Chloroform
Carbon tetrachloride
Trichlorethylene
1,1, 1-Trichloroethane
1975 to 1980
0.2
0.7
1.9
0.7
3.5
6.0
9.0
3.4
1.3
7.5
39
-------
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40
-------
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j
18. Reynen, F., and K. L. Kunel. Solvent Recovery System Nets
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20. Enneking, J. C. Control Vapor Emissions by Adsorption.
Union Carbide Corporation, New York, New York, 1973. 6 pp.
21. Oil Absorption System for Vent Solvent Recovery. Engineer-
ing Management, Inc., Park Ridge, Illinois. 1 p.
22. Pickett, G. E., J. A. Jacomet, and L. J. Nowacki. Disposi-
tion of Organic Solvents Recovered in Carbon Adsorption
Systems in the Industrial Surface Coatings Industry. Con-
tract 68-01-3159, Task 5, U.S. Environmental Protection
Agency, Cincinnati, Ohio, December 1976. 43 pp.
r 41
-------
23. Solvent Loss by Evaporation Cut 95% by Recovery System.
Chemical Processing, 38(1):25, 1975.
24. Solvent Recovery and Pollution Control Using Industrial
Distillation Equipment. No. FB-118, Hoffman Filtration
Systems, New York, New York, 1974. 32 pp.
25. Reay, W. H. Recent Advances in Thin-Film Evaporation.
Luwa (U.K.) Ltd., London, England (reprinted from The
Industrial Chemist, June 1963). 5 pp.
i
26- Nelson, W. L. Petroleum Refinery Engineering, Fourth
Edition. McGraw-Hill Book Company, New York, New York,
1958. pp. 252-261.
27. Nelson, W. L. Questions on Technology: Non-Condensable
Gases Handled During Vacuum Distillation. The Oil and Gas
Journal, 49(April 5):100, 1951.
28. Clausen, J. F., R. J. Johnson, and C. A. Zee. Destroying
Chemical Wastes in Commercial Scale Incinerators, Facility
Report No. 1. Contract 68-01-2966, U.S. Environmental .Pro-
tection Agency, Washington, D-C., October 1976. 116 pp.
29. Brighton Solvent Reclaiming Systems. Bulletin No. RS-4,
Brighton Corporation, Cincinnati, Ohio. 6 pp.
30. System Strips Solvents, Separates Solids Simultaneously.
Chemical Engineering, 83 (25):93-94, 1976.
31. Continuous Purification of Waste Solvents. Chemical Pro-
cessing (London), 20(1):17, 1974.
32. Marn, P. J., T. J. Hoogheem, D. A. Horn, and T. W. Hughes.
Source Assessment: Solvent Evaporation - Degreasing.
Contract 68-02-1874, U.S. Environmental Protection Agency,
Cincinnati, Ohio. (Final document submitted to the EPA by
Monsanto Research Corporation, January 1977.) 180 pp.
33. 1972 National Emissions Report; National Emissions Data
System (NEDS) of the Aerometric and Emissions Reporting
System (AEROS). EPA-450/2-74-012, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina,
June~1974. 434 pp.
34. TLVs® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1976. American Conference of Governmental
Industrial Hygienists, Cincinnati, Ohio, 1976. 97 pp.
42
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35. Manual on Disposal of Refinery Wastes, Volume on Atmos-
pheric Emissions. American Petroleum. Institute, Washington,
D.C., February 1976. pp. 7-1 through 7-14.
36. Evaporation Loss in the Petroleum Industry-Causes and
Control Bulletin No. 25B, American Petroleum Institute,
Washington, D.C., 1959. 59 pp.
37. Liptak, B. G. Environmental Engineer's Handbook, Vol. 2.
Chilton Book Company, Radnor, Pennsylvania, 1974. 1340 pp.
38. Control Techniques for Hydrocarbon and Organic Solvent
Emissions from Stationary Sources. National Air Pollution
Control Administration Publication No. AP-68, U.S. Depart-
ment of Health, Education, and Welfare, Washington, D.C.,
March 1970. pp. 1-1 to 7-3.
39. Air Pollution Engineering Manual, Second Edition. J. A.
Danielson, ed. Publication No. AP-40, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina,
May 1973. 987 pp.
40. Background Information for Establishment of National Stan-
dards of Performance for New Sources, Vegetable Oil Industry
(Draft). Contract CPA 70-142, Task 9h, U.S. Environmental
Protection Agency, Raleigh, North Carolina, July 1971.
64 pp.
41. Te'ale, J. M. Fast Payout from In-Plant Recovery of Spent
Solvents. Chemical Engineering, 84 (3):98-100, 1977.
42. Emmerling, J. Economical Recovery of Waste Solvent Provided
by System. Chemical Processing, 38(4):22-24, 1975.
43. Evaporation Loss from Fixed Roof Tanks. API Bulletin 2518,
American Petroleum Institute, New York, New York, 1962.
38 pp.
44. Use of Variable Vapor Space Systems to Reduce Evaporation
Loss. API Bulletin 2520, American Petroleum Institute,
New York, New York, 1964. 14 pp.
45. Petrochemical Evaporation Loss from Storage Tanks. API
Bulletin 2523, American Petroleum Institute, New York,
New York, 1969. 14 pp.
43
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APPENDIX A
NAMES AND LOCATIONS OF PRIVATE CONTRACTORS RECLAIMING
WASTE SOLVENTS IN THE 'UNITED STATES
Table A-l lists private U.S. contractors engaged in solvent
recovery.
TABLE A-l. PLANTS ENGAGED IN SOLVENT RECOVERY
AS PRIVATE CONTRACTORS9
State
Plant
Arizona
4
California
Colorado
Connecticut
Delaware
Florida
Georgia
Illinois
10
Dyna-Clean Labs, Phoenix
Fluid Conditioning Co., Phoenix
Western Oil Co., Phoenix
Southwest Solvents, Phoenix
RHO-CHEM, Inglewood
James B. Bachelor Co., Whittier
Baron Blakeslee, Belmont
Chem-Serv., Pinedale
Davis'Chemical Co., Los Angeles
Gold Shield Solvents; Los Angeles
Oil and Solvent Process, Azusa
Romie Chemical Corp., Palo Alto
Solvent Distilling Serv., San Jose
Bateman Chemicals, San Diego
Zero Waste Systems, San Francisco
Mountain Chemicals, Denver
Solvent Recovery Service, Southington
Aldorado Chemical Services, Wilmington
Gold Coast Oil Corp., Miami
City Chemicals, Orlando
Arisec Chemical Co., Douglasville
M and J Solvents Co., Atlanta
Acme Solvent Reclaiming Inc., Rockford
Fisher-Calb Chemicals and Solvent Co.,
Chicago
Rho Chemical Co., Joliet
Data obtained from industry contacts and Reference 9.
(continued)
44
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TABLE A-l (continued).
State
Plant
Illinois
Indiana
Kansas
Kentucky
Maryland
Massachusetts
Michigan
e
Missouri
New Jersey
10
Custom Organics, Chicago
Refining Products Division, Chicago
Syn-Sol Corp., Chicago
Midwest Solvent Recovery Co., Chicago
Crest Chemical Services, Inc., Chicago
American Ceca Corp., Oakbrook
Barker Chemical Co.
American Chemical Services, Griffith
Seymour Manufacturing Co., Seymour
Conservation Chemical Co., Indianapolis
Hammond Solvents Recovery Service, Hammond
Inland Chemical Corp,, .Fort Wayne
Chemical Commodities, Olathe
George Whitesides, Louisville
Inland Chemical, New Castle
Galaxy Chemicals, Inc., Elkton
Browning-Ferris, Baltimore
Montvale Laboratories, Stoneham
Re-solve, .Inc., New Bedford
Silvesim Chemical Corp., Lowell
Marylin Engineering Corporation, Boston
Cannons Engineering Corp., Boston
Mancor Chemical and Equipment Co., Boston
Gold Shield Solvents, Detroit
Gold Shield Solvents, Grand Rapids
Organic Chemicals, Grand Rapids
Nelson Chemicals, Detroit
Thomas Solvent Co., Detroit
Chemical Recovery Systems, Inc., Romulus
U.S. Chemical Co., Detroit
Spartan Chemical Co., Grand Rapids
Conservation Chemical Co., Kansas City
Clayton Chemicals, St. Louis
National Converters
General Scientific
Gold Shield Solvents, Riverton
Hogan Solvents and Chemicals, Kearny
Marisol Inc. , Middlesex
Perk Chemical Co-, Elizabeth
Scientific Chemical Processing, Carlstadt
Solvent Recovery Service,
C.P.S., Old Bridge
Swope Oil and Chemical Co.
Linden
Pennsauken
(continued)
45
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TABLE A-l (continued).
State
Plant
New York
1
North Carolina
Ohio
1
Oregon
Pennsylvania
Rhode Island
South Carolina
Tennessee
Texas
Washington
Wisconsin
Bell Chemical Co., Long Island
Chemical and Solvent Distillers, Astoria
Chem-Trol Pollution Services, Model City
Recycling Laboratories, Syracuse
Ajax Chemical Corp., Floral Park
Aceto Chemical Co., Flushing
Frontier Chemical Waste Processing Co.,
Niagara Falls
Gold Shield Solvents, Charlotte
Seaborg Chemical, Jamestown
Chemical Solvent Inc., Cleveland
Chemtron Corp., Avon
Hukill Chemical Corp., Cleveland
Chemical Recovery Systems, Elyria
Spray-Dyne Corp., Fernald
Klor Kleen, Inc., Cincinnati
Systech Waste Treatment, Franklin
Chempro of Oregon, Portland
Spe-de-Way Products Co., Portland
Tri State Chemicals, Inc., Philadelphia
Jones Chemical Reclaiming, Erie
Roberts Solvent Co., Philadelphia
Colonial Chemical Co., Johnstown
G. M. Gannon Co., Inc., Warwick
Jadco Corp., Greenville
Groce Laboratories, Greer
George Mills Industries, Nashville
G-M Solvent and Material Recycling, Nashville
Mid-State Solvent Recovery, LaVergne
Chemical Recycling Inc., Willie
Western States Refining co., Dallas
Lortep Laboratories, Inc., Houston
Nuclear Sources and Services, Houston
Emchem Corp., Houston
Chemet Corp., Houston
Chemical Processors, Inc., Seattle
Western Processing Co., Seattle
Seattle Chemical Co., Seattle
Milwaukee Solvents and Chemicals, Menom Falls
Rogers Laboratories, Milwaukee
Waste Research and Reclamation Co., Eau Claire
North Central Chemical, Inc., Madison
Commerce Industrial Chemicals, Milwaukee
46
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APPENDIX B
RESULTS AND SAMPLE CALCULATIONS FOR PRESURVEY SAMPLING
AT A PRIVATE CONTRACTOR SOLVENT RECLAIMING PLANT9
Air emissions from a condenser vent at a solvent reclaiming plant
were sampled for total hydrocarbons in two 1-hr periods. The
samples, both in aqueous suspensions, were analyzed for total
organic carbon with the following results:
First Run Sample A 1,295 mg carbon
Second Run Sample B 1,977 mg carbon
An emission factor was calculated in grams of hydrocarbons
emitted per kilogram of solvent reclaimed, using the following
data:
Sample A Composition: 1,295 mg carbon
100 m£ distilled H2O
33.6 m2, process steam
699 kg solvent/hr reclaimed
2.27 x 10^ m£ process steam/hr utilized
First, total hydrocarbons (HC) were calculated by converting the
mass of carbon to an equivalent mass of methane (CH^):
/1.298 g carbonV 1 mole carbon \ / 1 mole CH^ \ /16.043 g CHU\
\ 1 /V12.011 g carbon/ \1 mole carbon/ \ 1 mole CH^ /
= 1.734 g HC
An emission factor was then calculated using the known amount of
solvent reclaimed by the plant over time and the amount of steam
utilized by the plant per hour:
/ 1.734 g HC \ / 2.27 x IP*4 m£ steam \ = 1.7 g HC
\33.6 m£ steam/\699 kg reclaimed solvent/ kg reclaimed solvent
An emission factor of 1.8 g HC/kg reclaimed solvent was deter-
mined for Sample B utilizing the above calculations.
aNonmetric units are used in this appendix since they correspond
to those used in presurvey data calculations.
47
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Five storage tanks containing wastes on reclaimed solvents were
loaded on site at the plant. Solvent is emitted as a vapor from
such tanks during daily ambient temperature changes and loading
procedures. Emission factors were determined for these tanks by
calculating their breathing and working losses of stored solvent,
based on the following equations, which were developed and
reported in the referenced API Bulletins (35, 43-45).
Step 1. Calculate the equivalent gasoline breathing loss:
T - 24 I P \° ' 68 nl.73 /HMO. 51 /AT\0.50 p n (B-l}
LY ~ TTOOO" \14.7 - P) D (H } (AT) FPC (B L)
where L = equivalent gasoline breathing loss, bbl/yr
P = vapor pressure of material stored at bulk
temperature, psia
D = tank diameter, ft
H' = tank outage, ft
AT = average ambient temperature change, °F
F_. = paint factor
i ir l
C = diameter factor
The yearly average bulk temperature of stored solvent was esti-
mated to be 60°F. A vapor pressure for the solvent was estimated
by reviewing vapor pressures of selected solvents at 60°F. Tank
dimensions were given by plant personnel at the time of sampling.
The average ambient temperature change, AT, was taken as 19°F,
the national average value. The paint factors, F , were deter-
mined by the outside colors of the tanks. Diameter factors, C,
were determined from a graph given in Reference 42; they are
between 0.25 and 1.0.
(43) Evaporation Loss from Fixed Roof Tanks. API Bulletin 2518,
American Petroleum Institute, New York, New York, 1962.
38 pp.
(44) Use of Variable Vapor Space Systems to Reduce Evaporation
Loss. API Bulletin 2520, American Petroleum Institute,
New York, New York, 1964. 14 pp.
(45) Petrochemical Evaporation Loss from Storage Tanks. API
Bulletin 2523, American Petroleum Institute, New York,
New York, 1969. 14 pp.
48
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Step 2. Calculate the equivalent gasoline working loss:
Fg = T07MO PVNKT
where F = equivalent gasoline working loss, bbl/yr
V = tank capacity, bbl
N = number of turnovers per year
K = turnover factor = 1.0 for N 1 36
-S for N > 36
Step 3 . Compute total equivalent gasoline loss, L :
Lg = Ly + Fg CB-3)
Step 4 . Compute petrochemical losses:
L = 0.08(|)Lg (B-4)
where L = total petrochemical loss, bbl/yr
M = molecular weight of chemical stored
W = liquid density of chemical stored, Ib/gal
Step 5. Calculate emission factor:
L; = L(42) (W) (B-5)
E' o Li- (B-6)
E = |^- (B-7)
where Lj = petrochemical loss, Ib/yr
Cap = production capacity, ton/yr
E1 = emission factor, Ib/ton
E = emission factor, g/kg
Table B-l lists the input data for each storage tank and its
calculated emission factor. The number of turnovers for each
tank was estimated by noting the plant production capacity and
tank size.
49
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TABLE B-l.
INPUT DATA AND EMISSION FACTORS FOR FIXED-ROOF STORAGE
TANKS AT A SOLVENT RECLAIMING PLANT (PRESURVEY STUDY)
Input Date
Annual production capacity, tons/yr
Average ambient temperature, °F
Average ambient temperature change, °F
Molecular weight of stored material, Ib/lb-mole
Liquid density, Ib/gal
True vapor pressure at bulk temperature, psia
Bulk temperature, °F
Tank diameter, ft
Tank height, ft
Paint factor
Diameter factor
Turnover factor
Number of turnovers per year
Tank capacity, bbl
1
4,800
60
19
74.20
7.0
1.67
60
8.0
18.0
1.46
0.4
0.4
137
167
2
4,800
60
19
74.20
7.0
1.67
60
8.0
8.0
1.20
0.4
0.3
228
72
3
4,800
60
19
74.20
7.0
1.67
60
8.0
8.0
1.2
0.4
0.4
137
72
4
4,800
60
19
74.20
7.0
1.67
. 60
8.0
8.0
1.2
0.4
0.4
137
72
5
4,800
60
19
74.20
7.0
1.67
60
11.0
15.0
1.46
0.55
0.70
52
228
Emission factor, g/kg
0.1566
0.0775
0.0648
0.0648
0.1821
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A source severity was calculated for the plant from condenser
vent and storage tank emission data. To determine source severity,
a maximum ground level concentration, xm=v, is calculated as
follows: m="
2 Q
xmax = -
where Q = mass emission rate, g/s
u = average wind speed, m/s
H = effective emission height, m
e = 2.72
= _ (2) (0.44) _
xmax (3.14) (6Z) (2.72) (4.5)
= 6'36 x W
The mass emission rate, 0.44 g/s, was determined by the emission
factor and plant production capacity. The national average wind
speed of 4.5 m/s was used for the average wind speed, u. The
effective emission height for the plant has been given as 6 m.
Since the plant is a continuously emitting source and xmax repre-
sents a value for a short-term averaging time (approximately 3
min) , a maximum mean ground level concentration, X^ax f°r time
intervals between 3 min and 24 hr is estimated:
- 17
7 = x I o (B-9)
Amax Amax —
where t = short-term averaging time (3 min)
t = averaging time, min
Hydrocarbons are a criteria pollutant; the averaging time is
therefore 180 min by definition at the primary ambient air
quality standard, and:
3 \ 0. 17
X = 6.36 x -
Amax
= 3.17 x 10
-If
Source severity in this case is defined as the ratio of
to the primary standard for hydrocarbons, which is
1.6 x I0~k g/m3.
S =
51
-------
where F = the primary standard for hydrocarbons
= 3.17 x IP"1*
b 1.6 x 10-1*
S = 1.9
Still bottom wastes from the distillation operation were land-
filled rather than incinerated. No particulate emissions were
evident from the solvent reclaiming operation. The composition
of the still bottom wastes is shown in the total in Table 4.
52
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GLOSSARY
affected population: Number of nonplant persons.exposed to con-
centrations of airborne materials which ,,are present in
concentrations greater than a determined hazard potential
factor.
* /
criteria pollutants: Emission species for which ambient air
quality standards have been established; these include
particulates, sulfur oxides, nitrogen oxides, carbon
monoxide.
emission factor: Weight of material emitted to the atmosphere
per unit of produced acrylonitrile, e.g., g material/kg
product.
incinerator: Thermal oxidizer used for ultimate disposal of
acetonitrile and hydrogen cyanide byproducts and plant
residues.
material: Term used in reference to waste in reclaimed solvents,
reflux: Condensed solvent which flows countercurrently to
rising solvent vapors in the rectification column during
distillation.
sludge: Contaminants which have been separated from solvents
during their reclamation.
solvent recovery or reclamation: Process of restoring a waste
solvent to a condition where it can be reused by industry.
source severity: Ratio of the maximum mean ground level concen-
tration of emitted species to the hazard factor for the
species.
still bottom: Sludge which has been separated from solvents
during distillation; usually drawn off from the
evaporation.
threshold limit value: Refers to airborne concentrations of
substances and represents conditions under which it is
believed that nearly all workers may be repeatedly exposed
day after day without adverse effect (34).
waste solvent: Solvent which has become contaminated through
industrial use.
53
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TECHNICAL REPORT DATA
(Please nod Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-78-004f
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
SOURCE ASSESSMENT:
RECLAIMING OF WASTE SOLVENTS,
State of the Art
6. REPORT DATE
April 1978 issuing date
8. PERFORMING ORGANIZATION CODE
. AUTHOR(S)
D. R. Tierney and T. W. Hughes
8. PERFORMING ORGANIZATION REPORT NO
MRC-DA-727
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
10. PROGRAM ELEMENT NO.
1AB604
11. CONTRACT/GRANT NO.
68-02-1874
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory-Cin., OH
Office Of Research and Development
U.S. Environmental Protection Agency
Cincinnati. Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Task Final 8/76 - 11/77
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
IERL-Ci Task Officer for this report is R. J. Turner, 513/684-4481.
16. ABSTRACT
This document reviews the state of the art of air emissions from the reclaiming
of waste solvents. The composition, quantity, and rate of emissions are
described. Waste solvents are organic dissolving agents which are contaminated
with suspended and dissolved solids, organics, water, other solvents, and/or
other substances. Reclaiming consists of restoring a,waste solvent to a con-
dition that permits its reuse. A representative plant was defined in order to
determine the potential environmental impact of the solvent reclaiming industry-
Source severity was defined as the ratio of the time-averaged maximum ground
level concentration of a pollutant to a hazard factor. For criteria pollutants,
the hazard factor is the ambient air quality standard; for noncriteria pollutants,
it is a reduced TLV. In a representative plant, the hydrocarbon source severity
is 0.31, and particulate source severity is 0.0085; for selected solvents
ranging from acetone to butanol, source severities ranged from 0.0063 to 0.05.
Hydrocarbon emissions are controlled using floating roofs, refrigeration, and
conservation vents for storage tanks, and packed scrubbers and secondary con-
densers for distillation units. Particulate control from incinerator stacks is
accomplished using wet scrubbers.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
Air Pollution
Assessments
Solvents
Hydroc arbons
Air Pollution Control
Source Assessment
Particulate
c. COSATI Field/Group
68A
8. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS {This Rtport)
Unclassified
1. NO. Of PAGES
66
2O. SECURITY CLASS (Thispage)
Unclassified
27. PRICE
CPA Form 2220-1 (t-73)
54
*U.& GOVERNMENT PRINTING OFFICE:1978 260-880/49 1-3
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