August 1992
ON-SITE WASTE INK RECYCLING
Technology Evaluation Report
by
Arun R. Gavaskar, Robert F. Olfenbuttel, and Jody A. Jones
Battelle
Columbus, Ohio 43201
Contract No. 68-CO-0003
Work Assignment No. 0-06
Project Officer
Lisa Brown
Waste Minimization, Destruction, and Disposal Research Division
Risk Reduction Engineering Laboratory
Cincinnati, Ohio 45268
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI. OHIO 45268
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NOTICE
This material has been funded wholly or in part by the U.S. Environmental Protection
Agency (EPA) under Contract No. 68-CO-0003 to Battelle. It has been subjected to the Agency's
peer and administrative review and approved for publication as an EPA document. Approval does
not signify that the contents necessarily reflect the views and policies of the U.S. Environmental
Protection Agency or Battelle; nor does mention of trade names or commercial products constitute
endorsement or recommendation for use. This document is intended as advisory guidance only to
the printing industry in developing approaches to waste reduction. Compliance with environmental
and occupational safety and health laws is the responsibility of each individual business and is not
the focus of this document.
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FOREWORD
Today's rapidly developing and changing technologies and industrial products and
practices frequently carry with them the increased generation of materials that, if improperly dealt
with, can threaten both public health and the environment. The U.S. Environmental Protection
Agency (EPA) is charged by Congress with protecting the Nation's land, air, and water resources.
Under a mandate of national environmental laws, the agency strives to formulate and implement
actions leading to a compatible balance between human activities and the ability of natural systems
to support and nurture life. These laws direct the EPA to perform research to define our
environmental problems, measure the impacts, and search for solutions. :
The Risk Reduction Engineering Laboratory is responsible for planning, implementing,
and managing research, development, and demonstration programs to provide an authoritative,
defensible engineering basis in support of the policies, programs, and regulations of the EPA with
respect to drinking water, wastewater, pesticides, toxic substances, solid and hazardous wastes,
Superfund-related activities, and pollution prevention. This publication is one of the products of
that research and provides a vital communication link between the researcher and the user
community.
Passage of the Pollution Prevention Act of 1990 marked a strong change in the U.S.
policies concerning the generation of hazardous and nonhazardous wastes. This bill implements the
national objective of pollution prevention by establishing a source reduction program at the EPA and
by assisting States in providing information and technical assistance regarding source reduction. In
support of the emphasis on pollution prevention, the "Waste Reduction Innovative Technology
Evaluation (WRITE) Program" has been designed to identify, evaluate, and/or demonstrate new
ideas and technologies that lead to waste reduction. The WRITE Program emphasizes source
reduction and on-site recycling. These methods reduce or eliminate transportation, handling,
treatment, and disposal of hazardous materials in the environment. The technology evaluation
project discussed in this report emphasizes the study and development of methods to reduce
waste. ' i
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
iii
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ABSTRACT
This evaluation addresses the product quality, waste reduction, and economic issues
involved in recycling a printing ink in a facility such as The Hartford Courant newspaper in Hartford,
Connecticut. The specific recycling unit evaluated is based on the technology of distillation and
filtration. Ink recycling was found to have good potential as a means of waste reduction and long-
term cost saving. Product quality was evaluated by conducting selected performance tests and
comparisons of the printed material by qualified professionals of the spent, recycled, and virgin
inks. A good product quality of the recycled ink was also achieved by this unit. The recycled ink
fared well in laboratory performance tests such as viscosity, grind, residue, tack, tinting strength,
water content, and water pickup. Ink and solvent that would have gone to waste were recovered
and reused. The resulting cost saving gave a payback period of about ten years.
This report was submitted in partial fulfillment of Contract Number 68-CO-0003, Work
Assignment 0-06, under the sponsorship of the U.S. Environmental Protection Agency. This report
covers the period from September 10, 1990 to August 30, 1992, and work was completed as of
August 30, 1992.
IV
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TABLE OF CONTENTS
Page
NOTICE ii
FOREWORD j iii
ABSTRACT iv
ACKNOWLEDGEMENTS . viii
LIST OF TABLES vii
LIST OF FIGURES vii
SECTION 1
PROJECT DESCRIPTION . . . . . 1
PROJECT OBJECTIVES . 1
DESCRIPTION OF THE SITE , . . 2
DESCRIPTION OF THE TECHNOLOGY 2
SUMMARY OF APPROACH 4
Product Quality Evaluation . . . . 4
Waste Reduction Evaluation 4
Economic Evaluation 5
SECTION 2
PRODUCT QUALITY EVALUATION . . 6
ON-SITE TESTING 6
ANALYTICAL RESULTS 8
Viscosity 8
Grind , . . 10
Residue 10
Tack 11
Relative Tinting Strength 11
Water Content 12
Water Pickup and Bleeding 12
PRINTABILITY OF THE RECYCLED INK . 13
Densitometer Test '.. 13
Viewe'r Evaluation 16
PRODUCT QUALITY ASSESSMENT 19
SECTION 3
WASJTE REDUCTION POTENTIAL 21
WASTE VOLUME REDUCTION 21
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TABLE OF CONTENTS
(Continued) Page
POLLUTANT REDUCTION . . . . . 22
WASTE REDUCTION ASSESSMENT ; 27
SECTION 4
ECONOMIC EVALUATION 28
MAJOR OPERATING COSTS . 28
REVENUE FROM RECYCLED PRODUCT 28
VALUE OF PAYBACK-PRELIMINARY ESTIMATE 30
ECONOMIC ANALYSIS 30
Capital Costs j 30
Operating Cost/Revenue 32
Results of Economic Analysis 32
ECONOMIC ASSESSMENT 32
SECTION 5
QUALITY ASSURANCE 38
ON-SITE TESTING 38
LABORATORY ANALYSIS 38
LIMITATIONS AND QUALIFICATIONS . '. 39
SECTION 6
CONCLUSIONS AND DISCUSSION 4.1
SECTION 7
REFERENCES 43
LIST OF APPENDICES
APPENDIX A
DESCRIPTION OF PRINTING PROCESSES 44
APPENDIX B
DESCRIPTION OF PRINTING INKS 46
APPENDIX C
DENSITOMETER TEST DISCUSSION 48
APPENDIX D
THE HARTFORD COURANT INK RECYCLING SYSTEM
OPERATING COST ESTIMATE t. 50
VI
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LIST OF TABLES
Pace
TABLE 1. ON-SITE TESTING DESCRIPTION 7
TABLE 2. RESULTS OF PRODUCT QUALITY ANALYSES ; 9
TABLE 3. RESULTS OF DENSITOMETER READINGS ON THE NEWSPAPERS 14
TABLE 4. MEANS AND STANDARD DEVIATIONS FOR DENSITOMETER i
READINGS ACCORDING TO INK TYPE AND SIDE OF PAGE . 15
TABLE 5. RESULTS OF VISUAL JUDGING FOR PRODUCT QUALITY 18
TABLE 6. WASTE REDUCTION POTENTIAL : 21
TABLE 7. RESULTS OF ORGANIC ANALYSIS OF WASTEWATER 23
TABLE 8. RESULTS OF METALS ANALYSIS OF WASTEWATER (//G/L) 24
TABLE 9. ACUTE TOXICITY ANALYSIS OF WASTEWATER--SCREEN TEST 25
TABLE 10. ACUTE TOXICITY ANALYSIS-DEFINITIVE TEST 26
TABLE 11. MAJOR OPERATING COSTS 29
TABLE 12. CAPITAL COSTS FOR THE ECONOMICS WORKSHEET 31
TABLE 13. ANNUAL OPERATING COST/REVENUE INPUTS ;
TO THE ECONOMICS WORKSHEET :. . . .' 33
TABLE 14. INCREASED ANNUAL REVENUES AND OPERATING
SAVINGS FROM RECYCLING . . 34
TABLE 15. RETURN ON INVESTMENT (ROD . 35
TABLE 16. PRECISION DATA FOR METALS ANALYjS 39
TABLE 17. ACCURACY DATA FOR WASTEWATER ANALYSES 40
LIST OF FIGURES ;
Figure 1. Waste Ink Recycling Process 3
Figure 2. Comparison Between Newspapers Printed with
Virgin Ink and Recycled Inks 17
Figure A. Offset Planographic (Lithographic) Printing 45
VII
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ACKNOWLEDGEMENTS
The U.S. Environmental Agency and Battelle wish to thank Sumner Kaufman of ESSAR
Environmental Servjces (consultant to the Connecticut Hazardous Waste Management Service),
who located the technology and site for this project, and encouraged its inclusion in the WRITE
Program. The authors also appreciate the efforts of Paul Reynolds of The Hartford Courant for his
time;, input, and support during the evaluation.
VIII
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SECTION 1
PROJECT DESCRIPTION
This study, performed under the U.S. Environmental Protection Agency's (EPA) Waste
Reduction and Innovative Technology Evaluation (WRITE) Program, was a cooperative effort among
EPA's Risk Reduction Engineering Laboratory (RREL), Connecticut Hazardous Waste Management
Service (CHWMS), and The Hartford Courant. The objective of the WRITE Program is to evaluate,
in a typical workplace environment, examples of prototype or innovative commercial technologies
that have potential for reducing waste. In general, for each technology to be evaluated, three
issues should be addressed.
First, it must be determined whether the technology is effective. Since waste
reduction technologies usually involve recycling or reusing materials, or using substitute materials
or techniques, it is important to verify that the quality of the recycled product is satisfactory for the
intended purpose. Second, it must be demonstrated that using the technology has a measurable
positive effect on reducing waste. Third, the economics of the new technology must be quantified
and compared with the economics of the existing technology. It should be clear, however, that
improved economics is not the only criterion for the use of the new technology. There may be
justifications other than saving money that would encourage adoption of new operating
approaches. Nonetheless, information about the economic implications of any such potential
change is important.
This evaluation addresses the issues involved in using a particular commercially
available technology offered by a particular manufacturer for recycling waste printing ink. The
recycling unit used in this study is a mobile unit offered by Separation Technologies Inc. Other
recycling units and technologies (with varying capabilities) applicable to the same wastestream
(waste ink) are also commercially available.
PROJECT OBJECTIVES
The goal of this study was to evaluate a technology that could be used to recycle
waste printing ink for reuse in lithographic (newspaper) printing operations. This study had the
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following critical objectives:
* Evaluate the effectiveness of the recycling unit in generating an ink of acceptable
quality
Evaluate the waste reduction potential of this technology '
Evaluate the cost of recycling versus the cost of former practice (disposal).
DESCRIPTION OF THE SITE
The ink recycling technology was tested at The Hartford Courant, a newspaper located
in Hartford, Connecticut. The Courant, which employs about 1,500 people, has a daily circulation
,of 225,000 and a Sunday circulation of 320,000. Approximately 200 gallons of waste ink are
collected per week. Most of the waste ink is black ink with a small amount of colored ink.
Previously, the ink was sent to Solvents Recovery Services and blended with other solvents to
create a supplemental fuel. Since October of 1990, waste ink has been recycled on-site and
reused for printing.
DESCRIPTION OF THE TECHNOLOGY
A detailed description of various types of printing processes and printing inks is
provided in Appendices A and B. The Courant uses the web-fed lithographic printing process.
During printing, excess ink contaminated with the blanket wash solvent, fountain solution (mostly
water), and paper dust is collected in trays underneath the presses. The black and colored waste
inks are collected together and processed through the recycling unit into a reusable black ink
product. The colored waste ink also ends up as black ink through this process.
The recycling process is shown in Figure 1. The major components qf the recycling
unit at the Courant were purchased on a skid from Separations Technologies Inc. Other equipment
was added as required. Trays containing waste ink from the press room are emptied on a 1/4-inch
wire mesh to remove nuts, bolts, and other gross contaminants. The waste ink then goes to a
large waste ink storage tank. When enough ink is available in this tank, a batch is processed.
Processing primarily involves vacuum distillation, filtration, and blending.
Waste ink from the storage tank is transferred to the distillation still and distilled at
140°C under vacuum. Solvent and water from the waste ink are vaporized, condensed (by a
chiller), and collected in a separator tank where water and solvent separate out into two phases
2
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Black and
Colored Waste
ma Larger Particles
| 1/4 in. J Wire Mesh
Press Room
l r
i
Waste Ink
Black Recycled Storage
Ink to Tank
t H
1
1 Final
Filter
J Virgin
Black i
Ink Y
Holding Tank <- Tank^_
L'ra*- _^_->^
(Recycled Ink)
'
Vaci
,
Mixer
i '
urn
i
Distlllatior
IS,,,,
r- - ^L"
r - <><*
\
' ^. Coarse
Filters
Condenser
1 ' v
Tn
" Reuse *- - Solvent
To *- - Water
Municipal
Drain o««-»«*«i'
separator
"*. ~l Tank
1
1
1
Fine
u -» Filters
- -^ J
Process Skid
Figure 1. Waste Ink Recycling Process.
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under gravity. The water is drained off and discharged to the municipal sewer (under permit), and
the solvent is reused in the presses. The ink in the distillation still is sent through 100 and 325
mesh filters to remove paper dust, and then transferred to a blending tank. At this point, a grind
test and a drawdown test are performed and the amount of virgin black ink required (typically three
to four tjmes the amount of the processed ink) for blending is determined. The virgin ink is added
to improve the color, consistency, and other functional properties of the processed ink to an
acceptable range. The processed ink, after the virgin black ink is blended into it, is now referred to
as the final "recycled" ink.
After blending, the recycled ink is transferred to a clean holding tank. On demand,
valves in the ink supply lines switch the supply from virgin to recycled on certain presses. The
recycled ink is then drawn by a pump through a final 40-micron filter to the presses.
SUMMARY OF APPROACH
A Quality Assurance Project Plan (QAPP), prepared at the beginning of this study
(Battelle 1991), describes the detailed approach and scientific rationale used to evaluate the
recycling unit. The evaluation covered product quality testing, waste reduction estimation, and
economic analysis.
Product Quality Evaluation
A product quality evaluation must show that the quality of recycled ink is acceptable
compared with virgin ink (new off-the-shelf ink). This was accomplished by running the same
series of standard analytical and performance tests on the recycled (blended) and virgin inks and
comparing results. Whenever possible, a sample of waste ink was also analyzed,; and the results
were compared with those for the recycled ink to estimate the improvement in quality. Two
batches of waste ink were processed and sampled to ensure repeatability.
Waste Reduction Evaluation
The waste reduction evaluation was based on the amount of waste ink generated
annually by the Courant that is prevented from entering the environment as a result of recycling.
Recycling sidestreams were measured, namely, (a) the wastewater distillate that collects in the
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separator and (b) the residue on the filters. At the time of this evaluation, the wastewater was
being stored for eventual discharge to the municipal sewer line, following permission from the local
publicly owned treatment works (POTW). The filter residue is hauled away for incineration as a
supplemental fuel at an off-site contractor location. During this evaluation, the wastewater
distillate generated was collected and analyzed for parameters that are typically required by
POTWs.
Economic Evaluation .
The economic analysis included a comparison of operating costs for the new
technology (recycling) with the costs for the former practice (disposal). A return on investment
(ROD and payback period for the purchase of the recycling process equipment were also calculated.
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SECTION 2 ;
PRODUCT QUALITY EVALUATION \
As described in Appendix B, inks used for the offset lithographic printing process are
classified as oil or paste inks. Inks are composed of coloring matter (dyes or pigments) and a
vehicle or carrier (usually a mineral oil). Pigments, which can be organic or inorganic compounds,
are finely dispersed in the vehicle. During the printing process, the excess (waste) ink is collected
underneath the presses, along with excess fountain solution (water) and the blanket wash solution
(typically an aliphatic-aromatic blend solvent). Paper dust and fibers generated by the newsprint
also enter the waste ink. The recycling process should remove these impurities and restore the
properties of the ink.
Two batches of waste ink were processed through the recycling unit and samples of
the waste and recycled (blended) ink were collected for analysis. Samples of the virgin (new) ink
used at the Courant were also collected and analyzed. A comparison of the analytical results of
the waste and recycled inks indicates the improvement achieved by recycling. A comparison of the
analyses of recycled and virgin inks indicates how closely the recycled product approximates the
virgin product.
QN-8ITE TESTING
Table 1 describes the on-site testing conducted during this evaluation. Exact volumes
entering and leaving the various stages of the recycling system could not be measured. The best
estimates based on level indicators on the various tanks in the process are provided in Table 1.
The average volumes reported by the Courant during past operation are also mentioned and can be
used as representative of the system.
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TABLE 1. ON-SITE TESTING DESCRIPTION
Batch No.
1
2
Average15
Waste Ink
Volume8
(gallons)
<200
<200
200
Solvent
Distillate
(gallons)
negligible
negligible
<10
Wastewater
Distillate8
(gallons)
<80
<60
<70
Filter
Residue >
(gallons)
1 _ ;
1 ;
1
Processed
Ink8
(gallons)
<150
<150
120
8 Before blending. Volumes estimated from level indicators on each tank.
b Average from past operations. '
Both batches (Batch 1 and 2) processed during this evaluation had a processing time of about
48 to 50 hours. However, actual operator involvement was only 1 to 2 hours because most of the
i
recycling process is automated. Enough waste ink (75% black and 25% colored) had been
previously collected in the waste ink storage tank to run two batches for this evaluation. A sample
of the waste ink from the holding tank was collected with a bailer (a long tube open at both ends).
This ensured that the sample was representative of all levels in the tank. Considerable
inhomogeneity was noticed in the tank especially with respect to water, which was immiscible and
appeared to be accumulating in pockets at various points in the ink.
Each batch was transferred to the distillation still and processed at 140°F under vacuum.
Water was distilled off and collected in the separator tank. Usually a layer of solvent also distills
off and forms a separate layer on top of the water in the separator tank. However, in the two test
batches run, very little solvent was noticed in the distillate. Courant staff mentioned that solvent
volumes vary with each batch depending upon printing press operational variations. The water was
drained off from the separator tank and stored for municipal sewer disposal. At the time of the
evaluation, the Courant had applied for and received verbal approval from the local POTW for
discharge of this wastewater. The water was being stored pending formal approval. The solvent
generated in the distillate is reused as blanket wash in the presses.
After codling-to room temperature, the residual ink in the still was recirculated several times
through coarse (100 mesh) and fine (325 mesh) filters to remove paper fibers and other
particulates. After filtration, the ink was transferred to the blending tank. An intermediate sample
of the ink, at this stage, was subjected to a grind test (see following text) and a drawdown test by
Courant staff. These tests indicated how much virgin ink was to be blended into the processed ink
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to get an acceptable quality. The drawdown test was especially useful in comparing the processed
ink with virgin ink. In this test, about half a teaspoonful each of processed and virgin inks were
poured side-by-side on a piece of white paper. With an ink knife, the two inks were smeared in a
single stroke (drawdown) across the length of the paper. The two smears were then compared
visually. The virgin ink smear looked perfectly black and hid the whiteness of the paper. The
processed ink smear looked lighter and bled a bit of red along the edges of the smear (probably
from red pigment in the original waste ink). For both test batches, Courant staff determined that
3:1, virgin.-processed inks, was an acceptable ratio. According to Courant staff, this ratio can vary
between 3:1 and 5:1. A test mix was prepared at this ratio in a beaker and again subjected to the
grind and drawdown tests. Considerable improvement was noticed after blending in both grind and
drawdown tests. Thus, a proportional amount of virgin ink was added to the blending tank and
mixed with the processed ink. The resulting recycled ink was transferred to the recycled ink
holding tank for reuse. Samples of this recycled (blended) ink were collected for analysis. The
printability of recycled ink from Batch 1 was tested by switching from virgin to recycled ink
midway though a press run for the Sunday paper. Thus, the same image was printed several
times, first with virgin ink, and then with recycled ink. The two sets of newspapers were shown to
eleven people (not associated with the Courant) familiar on a day-to-day basis with printing and
imaging to compare the print quality.
ANALYTICAL RESULTS
The waste, recycled (blended), and virgin ink samples collected during the on-site testing were
analyzed in the laboratory for various characteristics. The results are shown in Table 2 and
described below.
Viscosity .
Inks are generally non-Newtonian fluids. The rheology of ink is an important factor in
controlling roller-to-plate transfer, fidelity of printing, drying speed, holdout, and trapping properties
obtained on the substrate (paper). Rheology is also a good indicator of color strength
(pigmentation). Viscosity, the resistance to flow, is the property generally used to describe
rheology. Viscosity does not completely describe the rheology of inks, but is useful in controlling
the ink quality during production and for specification acceptance between supplier and purchaser.
8
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TABLE 2. RESULTS OF PRODUCT QUALITY ANALYSES
CO
Analytical Tests8
o
Batch
No.
1,2
1
2
--
'
Sample Type
Waste Ink
Recycled lnkd
Recycled lnkd
Virgin Ink
Industry Standard
^^
&
'w ~
8.2
w o
NA
19
21
20
-
«-^
E
" *"
"Rib
r~
o ^
NA
0.4/0.3
0.6/0.3
0.3/0.0
0.4/0.2
3.4
4.4
3.9
4.0
3.7-4.3
.c
O) o>
~ =
c ^-
P W)
69
96
92
100
93
c
o
c
o
u
-M
CO
5
23.6
0.102
0.049
0.057
-
0.
D
O
Q.
0)
to '^
§ ~
NA
86
80
50
-
8 NA = Not analyzed. Tests could not be performed because of the large amount of water in the sample.
b 4/10 refers to 4 or 10 scratches at reported endpoints.
c Strength of recycled ink was compared to the virgin ink and given as a percentage of the virgin ink strength.
d Processed ink blended with virgin ink in the ratio 1:3.
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Ink viscosity was measured by ASTM D 4040-89 (Table 2). The viscosity of the spent ink
sample could not be measured because a considerable amount of immiscible water was present
throughout the ink mass, forming a separate phase. The viscosity of both recycled samples was
close to that of the virgin ink (within +_ 1 Poise) and in the normal range for newspaper inks,
indicating that this parameter had been restored during recycling.
Grind
This test (ASTM D 1316-87) uses an NPIRI Standard Grindometer to evaluate the fineness of
grind of printing inks, that is, the prevalence of oversize particles (contaminants) in the ink
dispersion. This NPIRI gauge runs 1 mil deep to flush. The ink is drawn down over this gauge, and
the depths at which 4 and 10 scratches in the ink film (caused by particles) appear are recorded (as
4-scratch and 10-scratch endpoints). The test measures the size of the largest particles in the
finished "dispersion arid not the average particle size or concentration of sizes. Oversize particles in
the ink may damage a printing plate and disrupt the appearance of ink films. Industry-suggested
guidelines recommend that there should not be 4 scratches above 0.4 mil or 10 scratches above
0.2 mil. ;
The spent ink could not be analyzed because its high water content caused it to run and form a
separate phase. The virgin ink sample was within the industry guidelines mentioned above. The
recycled ink came close, but exceeded both endpoints by 0.1 mil in Batch 1 and by 0.2 (4-scratch)
and 0.1 mil (10-scratch) in Batch 2. This indicates that some fine particulates were retained in the
recycled ink. .
Residue
The grind test indicates the size of the largest particles present in the ink. The residue test,
also called the wash-out test, measures the weight percentage of the solid particles (impurities)
larger than 325 mesh in the ink. In this test, 100 g of ink was mixed for 30 minutes with 50 mL of
naphtha. This mixture was poured through a 325-mesh standard sieve, and the residue on the
sieve was weighed. The percent by weight of this residue is reported in Table 2.
This test could not be performed on the spent ink sample because the naphtha formed a gei
with the contaminant water. The virgin ink showed very little residue (0.0019%}J The residue in
the recycled samples was an order of magnitude higher (0.0817% and 0.0735%), Industry
10
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recommends a level of around 0.01 % for newspaper inks. The higher residue content in the
recycled samples indicates that spent ink contains particles smaller than 325-mesh, or paper fibers
with a diameter less than 325-mesh, that escape the fine filters on the recycling unit. Blending
virgin ink at ratios greater than 3:1 {used for the test batches) would be one way of reducing the
residue percentage in the recycled ink, although the current residue levels do not appear to have
caused a significant difference in print quality (see subsection titled Printability of the Recycled Ink).
Tack
Tack is a Theological parameter representative of internal cohesion of the fluid. Tack of the ink
controls its high-speed transfer properties. It is a function of the force required to split a thin fluid
film of ink between two rapidly separating surfaces, such as between the plate cylinder and the
offset cylinder or between the offset cylinder and the newsprint. Tack (ASTM D 4361-39) was
measured as the frictional torque on a three-roller distribution system (B101 Electronic Inkometer)
in units of gram-meters (g-m). Tack was measured at speeds specific to the Courant (1200 rpm at
1 min for web-fed inks).
Industry recommends a range between 3.7 to 4.3 g-m for tack for this type of ink. The virgin
sample and the recycled sample from Batch 2 were 'vithin this range (Table 2). The recycled
sample from Batch 1 was slightly above this range. Press operators at the Courant did not think
that this slight deviation was of any significant concern. The waste ink sample was well below
acceptable range, indicating that recycling had considerably improved this parameter.
Relative Tinting Strenq.h
The waste ink at the Courant contains, in addition to black ink, some amounts of colored ink.
During recycling, the processed ink is blended with black virgin ink to restore its color and strength.
Color and strength are therefore important parameters of the recycled ink. Tinting strength of the
ink was measured by a method similar to ASTM Methods D 387, D 2745, and D 4838.
In this test (commonly called the bleach test), a standard white tinting base or bleach (white
pigment dispersed in a suitable vehicle) is added side-by-side to the virgin and recycled inks. The
amounts of bleach required to get equivalent color strength in the recycled samples and the virgin
sample is the relative tinting strength.
11
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Table 2 shows that if the virgin ink at the Courant Is used as the reference (100% relative
strength), the recycled ink in Batches 1 and 2 were within 4 and 8% respectively of the virgin ink.
The waste ink had a relative strength of only 69% (31 % deviation from virgin), indicating that
considerable improvement in tinting strength was achieved by recycling. Industry recommends that
relative tinting strength be within _+. 7% of the standard. If virgin (new) ink is considered as the
standard. Batch 1 was within the acceptable range and Batch 2 was slightly out of range. This
could have been corrected by blending virgin ink into Batch 2 at a ratio greater than the 3:1 used
for this batch, although current tinting strength values appeared to provide an acceptable print
quality (see subsection titled Printability of the Recycled Ink).
Water Content
Water gets into the waste ink because of the fountain solution used in lithographic printing.
This water alters the consistency and functional properties of the ink and has to be removed during
recycling. Water content of the ink samples was measured by ASTM D 1744-83 and results are
reported in Table 2. Water content was reduced by recycling from 23.6% in the waste ink to
levels comparable with those in virgin ink, indicating that most of the water was removed during
the distillation step.
Water Pickup and Bleeding _
The lithographic printing process requires that some fountain solution (mostly 'water) be
emulsified in the ink. This emulsifying capability of the ink was measured by the water pickup test
(ASTM D 4942-89). A measured amount of fountain solution (the same one used at the Courant)
is thoroughly mixed with the ink. Any unemulsified or free water is returned (decanted out of the
ink). The percent of water (fountain solution) picked up by the ink relative to its own weight is
recorded in Table 2. As part of this test, the color, pH, and conductivity of the return (free) water
was also measured. This test .was not performed on the waste ink because it already had a large
quantity of water. ,
The water pickup of recycled inks from Batches 1 and 2 was 86 and 80% respectively,
compared with 50% for the virgin ink. The water pickup of most inks is between 40 to 80% of
the weight of the ink. Newspaper inks are sometimes formulated to pick up far more fountain
solution depending on the type of press.
12
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Inks that bleed into the fountain solution could cause tinting in the non-image areas of the
newspaper. The virgin and recycled inks did not change the fountain solution to black, but the
recycled as well as virgin samples did change the returned {unemulsified) fountain solution from
clear to pink. The pH of the fountain solution as used was 6.5 before the test and changed by 0.1
pH units or less after the test (as measured in the unemulsified or returned fountain solution). A
drift of less than 0.5 pH is recommended, and the virgin as well as recycled samples were well
within this range.
PRINTABILITY OF THE RECYCLED INK
The above analytical tests indicate the quality of the recycled {blended) ink in terms of
laboratory measured parameters. The visual effect and behavior of the recycled ink, once it is
printed on a newspaper, was evaluated by (a) taking densitometer readings on black image areas of
newspaper pages printed with virgin and recycled inks and (b) requesting 11 experienced viewers
to record their preference for newspaper pages printed with recycled or virgin inks.
Densitometer Test
Three complete copies of the June 30, 1991 edition of the Hartford Courant were printed using
virgin ink, and three copies using recycled ink. All printing was done on the same press. The
switch from virgin to recycled ink was done within minutes to minimize other sources of variation.
From these six newspapers, an outer page (a "wrapper" page) and an inner page (a "core" page)
were selected, in order to gauge the effects of the two sides of the newsprint on the ink
evaluation. The same two pages were selected from each newspaper; thus all selected wrapper
pages contained identical printing, as did all selected core pages.
Densitometer readings were obtained on each selected page from three areas of solid ink
shading. The densitometer measures the concentration of black dots per unit area of the page,
thus indicating the uniformity and color strength of the ink layer on the newsprint. The three areas
selected for densitometer analysis on a given page were the same for each wrapper page and for
each core page. Table 3 contains the densitometer readings obtained from each area of the tested
pages. Higher densitometer readings indicated a higher ink density.
The statistical objective of the densitometer analysis was to determine primary sources of
variability present in the densitometer readings, and to determine whether the readings were
13
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TABLE 3, RESULTS OF DENSITOMETER READINGS ON THE NEWSPAPERS
Paper Type8
Wrapper -
Newspaper 1
Wrapper -
Newspaper 2
Wrapper -
Newspaper 3
Core -
Newspaper 1
Core -
Newspaper 2
Core -
Newspaper 3
Location
on
Pageb
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
Densitometer Readings (units)
Paper Printed Paper Printed
with with % Difference*1
Virgin Ink Recycled Ink0 (Recycled to Virgin)
0.95
0.99
0.98
0.91
0.95
1.00
0.94
0.97
0.91
1.05
1.00
1.02
» 1.08
1.02
1.01
1.05
1.01
0.97
1,10
1.00
1.09
1.08
1.03
1,11
1.07
1.02
1.04
0.99
1.01
0.92
1.06
1.01
1.02
1.01
0.97
0.98
14.6
1.0
10.6
17.1
8.1
10.4
12.9
5.0
; 13.3
-5.9
1.0
-10.3
-1.9
; -1.0
-1 .0
-3.9
-4.0
1.0
0 Wrapper refers to the exterior pages of a newspaper section while core refers to the interior
pages. Three complete editions were printed with virgin ink, and three with recycled ink.
b The same three locations were tested on each wrapper page and each core page.
0 Processed ink blended with virgin ink in the ratio 1:3,
d A positive % difference indicates that the tested areas were denser for recycled ink according
to the densitometer, and vice versa.
14
-------
statistically higher or lower for one ink than another. To meet this objective, an analysis of
variance procedure was applied to the densitometer readings. Based on the experimental design
used in the densitometer analysis, the effects of each of the following factors on the densitometer
reading were able to be estimated:
Ink used (recycled or virgin)
Type of page (wrapper or core)
« Location on the page (three distinct locations).
The results of the statistical analysis on densitometer readings inferred that the readings tended
to differ between the side of the page and the ink used. Table 4 contains the means and standard
deviations of the readings for each page side and ink, A more detailed discussion of the
differences in densitometer readings is included in Appendix C.
TABLE 4. MEANS AND STANDARD DEVIATIONS FOR DENSITOMETER READINGS
ACCORDING TO INK TYPE AND SIDE OF PAGE
Ink Type
Virgin
Recycled8
All Inks
Wrapper Page
0.9856 (0.0324)
1 .0600 (0.0387)
1 .0078 (0.0639)
Means (and Standard Deviations)
Core Page
1 .0233 (0.0324)
0.9967 (0.0387)
1.0100 (0.0373)
All Pages
0.9894 (0.0470)
1 .0283 (0.0497)
" Processed ink blended with virgin ink in the ratio 1:3.
In summaryi the densitometer readings (concentrations of black dots) were significantly higher
for recycled ink on the wrapper side (level of significance was 99.99%). On the core side, the
densitometer readings were marginally higher for virgin ink (level of significance was 93.46%).
Generally the differences were small and the denseness quality of the recycled and virgin inks can
be said to be comparable.
15
-------
Viewer Evaluation
A subjective comparison of the two inks was performed by having eleven viewers rate their
preferences between recycled ink and virgin ink as printed on newsprint. The viewers were experts
in the printing and printed material field. The visual examination was conducted .within five days
after printing because the print needs to be stable over this period, especially for the Sunday
edition. The criteria which the viewers used to rate their preferences were the following:
glossiness .
smoothness
« opacity
rub resistance-
» blackness
absorption/bleed-through
sharpness
Two pairs of pages were given to the viewers for subjective rating. One pair consisted of two
wrapper pages and one pair contained two core pages. Within each pair, one page was printed
using recycled ink and one with virgin ink. The two pages, both containing identical printing, were
labelled "page A" and "page B" to prevent the viewer from knowing the type of ink used in the
printing. These pages were selected for evaluation according to the type of imaging printed,
ensuring that both pages had at least some black patches, some half-tones, and some lettering of
different fonts and sizes. For each pair of pages, the viewers were asked to determine whether
they preferred page A or page 8 according to each criteria above. A non-preference response was
also permitted. A copy of the rating instrument used by the viewers is found in Figure 2.
In the subjective evaluation, it was of interest to determine the proportion of preferences for
virgin ink versus recycled ink, and not vice versa. Thus all non-preference responses were
combined with those responses indicating a preference for recycled ink. Table 5 contains a
summary of the numbers of viewers preferring virgin ink, according to each of the above criteria.
The results in Table 5 show that few, if any, viewers preferred virgin ink over recycled ink when
rating the wrapper page by the above criteria. The most viewers rating virgin ink over
16
-------
Figure 2
COMPARISON BETWEEN NEWSPAPERS PRINTED WITH VIRGIN AND RECYCLED INKS
We are trying to compare the quality of a newspaper printed with
virgin (newly manufactured) ink to that of a newspaper printed with
recycled ink. Recycled ink is ink reclaimed by processing the waste ink
collected underneath lithographic printing presses.
Please use your best personal judgement to compare the two pages of
the newspaper marked "A" with the corresponding two pages of the
newspaper marked "B" for the following qualities and mark your preference
in the following columns. If you cannot see any noticeable; difference in
the print quality of the two newspapers please mark the column "no
noticeable difference".
For page H-10
"A" looks better "B".looks better No noticeable
than "S" than "A" difference
SI oss
Smoothness
Opacity
Rub resistance
Quality of blackness
Absorption/bleed thru'.
Sharpness
For page J-4 ; -
A" looks better "i" looks better No significant
than "8" than "A" difference
Gloss
Smoothness
Opacity
Rub resistance
Quality of blackness
Absorption/bleed thru'_
Sharpness
Thank you for your cooperation.
17
-------
TABLE 5. RESULTS OF VISUAL JUDGING FOR PRODUCT QUALITY
oo
Wrapper Page (outer)
Upper 95%
Parameter
Glossiness
Smoothness
Opacity
Rub Resistance
Blackness
Absorption/
Bleed-Through
Sharpness
# Viewers
Preferring
Virgin Ink
0
0
0
3
0
2
1
# Viewers With
No Preference
or Preferring
Recycled Ink8
11
11
11
8
11
9
10
Confidence
Bound on the
Proportion
Preferring
Virgin Ink
0.238
0,238
0.238
0.564
0.238
0.470
0.364
# Viewers
Preferring
Virgin Ink
2
4
4
1
4
1
3
Core Page (inner)
# Viewers With
No Preference
or Preferring
Recycled Ink8
9
7
7
10
7
10
8
Upper 95%
Confidence
Bound on the
Proportion
Preferring
Virgin Ink
0.470
0.650
0.650
0.364
0.650
0.364
0.564
"Processed ink blended with virgin ink in the ratio.1:3.
-------
recycled ink did so according to rub resistance, and only three of the eleven viewers did so. No
viewers preferred virgin ink to recycled ink on the wrapper page according to glossiness,
smoothness, opacity, or blackness. :
When rating the core page, at least one viewer rated virgin ink over recycled ink in each of the
criteria. However, no more than four viewers preferred virgin ink for any one of the criteria for the
core page.
To determine the extent of variability in the proportion of viewers preferring virgin ink, a series
of upper 95% confidence bounds on the true proportion were calculated for each of the seven
criteria. These confidence bounds were calculated as follows, and are discussed further in
Hollander & Wolfe (1973):
11-x
upper conf. bound = 1 - '
(11-x) + (x + 1)*F(2(x + 1),2(11-x))
where x is the number of viewers preferring virgin to recycled ink, and F(A,B) is the 95th percentile
of the F distribution with A numerator degrees of freedom and B denominator degrees of freedom.
The calculated bounds are included in Table 5 for the wrapper and core pages. Note that when
two or less of the eleven viewers preferred virgin ink, the upper 95% confidence bound on the
proportion is less than 0.5. This states that the proportion of viewers preferring virgin ink is
significantly less than 0.5. In summary, there was no significant difference in print quality between
the virgin and recycled inks in the opinion of experienced viewers.
PRODUCT QUALITY ASSESSMENT ~
The product quality of the recycled ink was very good. In most of the laboratory tests
described above, the recycled ink matched the properties of the virgin ink. In some cases, the
recycled ink properties were slightly outside industry recommended ranges, although it should be
noted that these ranges are recommended by industry for newly manufactured inks. No standards
exist specifically for recycled inks, .and it is left to the users to determine acceptable ranges for the
ink. Recycled ink quality has been found to be acceptable at The Hartford Courant, where recycled
ink is regularly used for printing both the daily and Sunday newspapers, without any drop in
quality. Regular readers of the Courant have not noticed any difference in print quality. The panel
19
-------
of experienced viewers that evaluated the newspaper printed with virgin and recycled inks did not
notice any significant difference in quality either.
Improvements that can be made in the recycling system, as it now exists, should be in the area
of fine particulates removal. This could be addressed by increasing the blending ratio of
virgin.-processed inks from 3:1 (in this evaluation) to 4:1, which would further reduce the
concentration of the fine particulates in the ink. In fact, the Courant could automatically blend
virgin ink into the processed ink at ratios of 5:1 or higher given that the amount of processed ink is
such a small percentage of the total amount of ink required for production.
Another improvement could be to increase the efficiency of filtration. The fact that the residue
test showed some residue on the 325-mesh sieve in the laboratory indicates that the 325-mesh
filters on the recycling units may not be fully efficient. One difficulty could be that paper fibers
may have a lengthwise dimension greater than 325 mesh, but a fiber diameter of less than 325
mesh. Depending on its orientation, this fiber could either pass through or be retained on the filter.
Several more passes through the recycling unit filters may be required before such fibers are
removed. However, the slightly elevated levels of fine particulates in the recycled ink, compared to
virgin ink, did not noticeably influence the performance or printability of the recycled ink.
20
-------
SECTION 3
WASTE REDUCTION POTENTIAL
The waste reduction potential was measured in terms of (a) volume reduction and
(b) pollutant reduction. Volume reduction addresses the gross wastestream and affects
environmental resources (e.g., landfill space) expended during disposal (e.g., waste ink), whereas
pollutant reduction addresses the specific hazards of individual pollutants (e.g., heavy metals) in
the gross wastestream. . '
WASTE VOLUME REDUCTION
The waste-volume-reduction potential of this technology involves the amount of waste
ink prevented from being disposed into the environment (by landfilling, waste incineration or as
supplemental fuel). Table 6 lists the various wastestreams and waste volumes generated by
disposal and by recycling. The Courant generates approximately 175 gal/week qr 9,100 gal/yr
waste ink. Every 200 gal of waste ink contains, on average, about 80 gal of water and solvent
(mostly water), and the rest (120 gal) is ink. Previously, this waste ink was being disposed by a
waste hauler by incineration as supplemental fuel.
TABLE 6. WASTE REDUCTION POTENTIAL
i>
Wastestream Generated Amount Per Year
Current Practice \
1. Waste Ink 9,100 gal ;
With Recycling ;
i
1. Wastewater . . 3,049 gal
2. Residue (paper dust) 46 gal
21
-------
By recycling, the ink is recovered. The recycling wastestreams consist of water
(wastewater) from the separator and the paper-dust paste residue from the filters. Any solvent
that distills off is reused in the printing process. At the time of tnis evaluation, the wastewater
was being stored for discharging down the municipal sewer. The Courant it considering installing
an activated carbon filter for polishing off the organics in the wastewater, so that the water can be
used again. The paper-dust residue (about 1 gal/200 gal of waste ink processed) is disposed of by
off-site contractor incineration as supplemental fuel.
POLLUTANT REDUCTION
Individual pollutants present in the wastestreams are discussed in this section. As
described in Appendix B, the waste ink contains a number of components that potentially could
render it hazardous. The waste ink at the Courant has been tested and is not considered a
hazardous waste per RCRA, and can be disposed of according to state regulations for oily wastes.
However, solvent washes for other inks that contain lead or chromium in their formulation are listed
as hazardous waste (EPA Waste Number K086) under RCRA. In addition, other waste inks could
contain constituents that render them flammable or toxic. Many toxicity problems are caused by
the pigments used. Lead, chromium, barium, and organic compounds are common toxics in
pigments. Solvents in the waste ink are usually aliphatic-aromatic blends. These solvents may
contain hazardous organic constituents. By recycling, virtually all of these potential pollutants in
the waste ink are reused and thus prevented from entering the environment.
The recycling process generates paper-dust residue, which is basically a paste-like
substance containing paper fibers covered with a thick mass of ink. The hazai ds associated with
this residue are the same as discussed above for the ink, the advantage being that, for every 200
gal of waste ink, less than 1 gal of residue is generated.
The recycling process also generates wastewater as a wastestream. which the
Courant plans to discharge to the municipal sewer, after approval from the POTW is obtained. This
wastewater was analyzed for potential hazards during this evaluation. Two samples of the
wastewater, both from Batch 1, were collected. Two samples were collected because the
separator tank had to be emptied halfway through the distillation of Batch 1 to make room for more
distillate. The two samples represent the initial distillate and the later distillate. Results for the
chemical analysis are reported in Tables 7 and 8. A blank consisting of tap water collected at the
22
-------
TABLE 7. RESULTS OF ORGANIC ANALYSIS OF WASTEWATER
Aromatic Organtcs (mg/L)
c
o
e
a
1
Batch
No.
Sample
Type
SI
e
01
m
O
A
O
o
a
0)
c
o -
m
X)
o
o
5
C
C
jg
JC
3
O
X
u
1
(initial)
Wastewater 67.9
43.9
<0.0025 <0.002S <0.0025 <0.002S <0.0025 <0.0025
0.0177
0.425
1
(later)
Waste water 31.5
56.9
<0.0025 <0.0025 <0.0025
<0.0025
<0.0025
<0.0025
<0.0025
0.373
Blank
1.06
<0.5
<0.0025 <0.0025 <0.0025
<0.002S
<0.002S
< 0.0025
<0.0025
<0.0025
-------
TABLE 8, RESULTS OF METALS ANALYSIS OF WASTEWATER
Batch
No.
1 (initial)
1 (later)
..
Sample
Type
Wastewater
Wastewater
Blank
£
o |j
to 12
OJ «?
_i U
89.2 <4.1
17.3 <4.1
14.6 <4.1
E
.2
o
JC
U
<4.4
<4.4
<4.4
o
c
N
831
42.3
14.4
01
.*
.y
z
6.9
<3.4
69.0
i~
CD
o
o
14,600
662
95.1
-------
Courant was also analyzed to check for any extraneous contamination (from the tap water or
during sampling and analysis). The blank did not contain any significant levels of the analytes.
The organic analysis of the wastewater showed elevated levels of oil, grease, total
hydrocarbons, toluene, and xylene. The metals analysis of the wastewater showed elevated levels
of lead, zinc, and copper. These pollutants in the wastewater are components of the ink (vehicle
and pigment) or the blanket wash solvent that get carried over into the distillate., Because of these
pollutants, the wastewater cannot be discharged directly to natural waters but has to be treated.
At the time of the evaluation, the Courant had obtained verbal approval from thelPOTW for
discharging this wastewater to the local wastewater treatment plant where these pollutants will be
removed. The Courant is expected to generate approximately, 67 gal of wastewater per 200 gal of
waste ink, or 3,049 gal/yr. ;
Because toxicity of influents is a growing concern among POTWs, acute aquatic
toxicity tests were conducted on the wastewater. A distilled water control sample was also run
alongside each test sample. Before the test, the wastewater was gently aerated (as required by
the standard method) to increase dissolved oxygen from 4.7 mg/L to 9.0 mg/L, ahd pH was
adjusted from 4.7 to 8.4 with hydroxide. Acute toxicity was measured on two aquatic organisms
C. dubia (daphnids) and P. promelas (fathead minnows) according to EPA method 600/4-85/013.
In the screening test using 100% wastewater (as received), all organisms of both species died
within the first day after they were introduced into the wastewater (Table 9). Therefore a
definitive test (Table 10) was conducted with various dilutions of the wastewater to determine the
LC50 (lethal concentration at which at least half the organisms die). The definitive test was
conducted in duplicate for each dilution on the minnows.
TABLE 9. ACUTE TOXICITY ANALYSIS OF WASTEWATER--SCREEN TEST
Number of Live Organisms
Day
1
2
3
4
C. dubia"
100%
Wastewater
o
NA
NA
NA
Control
5
5
5
5
P. Dromelasb
100% ,
Wastewater
0
NA ;
NA
NA
Control
10
10
10
10
25
-------
" Five C. dubia (daphnids) were introduced into each tank on Day 0.
b Ten P. promelas (fathead minnows) were introduced into each tank on Day 0.
NA: Not applicable.
TABLE 10. ACUTE TOXICITY ANALYSIS-DEFINITIVE TEST
Water
Concentration
(%)
Control
6
12
25
50
100
£L
Day
1
5
0
0
0
0
0
dubia8
Number
2
5
NA
NA
NA
NA
NA
P. promelasb
Day Number
1
10/10
10/8
2/0
0/0
"0/0
0/0
2
10/10
7/7
0/NA
NA
NA
NA
' 3 ,
10/10
5/5;
NA
NA
NA
NA
4
10/10
4/3
NA
NA
NA
NA
a Five C. dubia {daphnids) were introduced into each tank on Day 0. |
b Ten P. promelas (fathead minnows) were introduced into each tank on Day 0. Test was
conducted in duplicate for each dilution,
NA: Not applicable.
The static acute toxicity test on the daphnids indicated that the LC50 for both 24-hr
and 48-hr tests was below 6%, the lowest concentration tested. The definitive test on the
minnows indicated that the 24-hr, 484ir, 72-hr, and 96-hr LC50s were 8.5%, 7,0%, 6.0%, and
<6%, respectively. The results show that the wastewater from the recycling process is highly
toxic and would need to be diluted at least 10 to 20 times to make it non-toxic. The swiftness
with which the' aquatic organisms died appears to indicate that toxicity is caused primarily by
organic constituents in the wastewater (when inorganic constituents such as heavy metals cause
toxicity, the organisms tend to die more slowly). Organic analysis of the wastewater (Table 7)
showed elevated levels of oil, grease, total hydrocarbons, toluene, and xylene. ;
This result indicates that the part of the solvent that co-distills out into the separator
tank may not be forming a separate phase easily. This would mean that (a) wastewater is
26 :. .
-------
evacuated from the separator tank without allowing enough time for the solvent to separate out
into a separate phase on top of the water or (b) that the solvent has some solubility in water or
may be forming a micro-emulsion. In the first case, the Courant could allow the Water to settle for
an extended period of time before draining the separator tank. In the second case, some other
means such as activated carbon filtration of the wastewater could be used, although the Courant is
not currently required to do so. It should be noted that the amount of wastewater generated
through the recycling process is so small (less than 80 gal/week) that it is not expected to cause
problems at the POTW, where it would get diluted several times by other influents and the
treatment process would remove the organics. However, to avoid letting the water go to waste, it
would be desirable to run it through an activated carbon filter and reuse it. The Courant is
considering such an addition.
WASTE REDUCTION ASSESSMENT
There is considerable potential for waste reduction by recycling waste ink. Valuable
resources such as ink and solvent, are recovered from the waste ink and reused. In the case of the
Courant, the amount of waste disposed has been reduced from 9,100 gal/yr of waste ink to 46
gal/yr of paper-dust and 3,049 gal/yr of wastewater. The wastewater is a lower hazard compared
to the waste ink. The volume of the wastewater stream can also be reduced considerably by
installing an activated carbon filter and reusing the water.
27
-------
SECTION 4
ECONOMIC EVALUATION
MAJOR OPERATING COSTS
The major operating costs associated with the disposal option and the recycling option
are given in Table 11. With disposal, the main cost is the fee charged by the waste hauler to take
the waste ink away for incineration. The Courant was paying $200/55-gal drum for disposal, plus
the cost of the empty drum itself ($30/drum).
With recycling, the major operating costs are for utilities (energy), labor, and disposal
of wastewater and paper-dust residue. Utility costs were estimated to be $105/batch (see
Appendix D for details). Utility costs were based on the energy requirements of the distillation still
(steam heat generated by a gas-fire boiler), distillation still agitator, ink pump, water pump, vacuum
pump, blend tank pump, blend tank mixer, day tank pump, and chiller (compressor, fan motor, and
coolant pump).
At The Hartford Courant no additional labor (other than that already employed for
disposal operations) was needed to operate the recycling equipment. Although no extra labor was
needed at the Courant, one hour of operator time per batch (including time for intermediate quality
tests on the ink) was considered for the economic analysis. The paper-dust residue on the filters is
hauled away for incineration at a cost of $250/55-gal drum. The wastewater from the separator
would be discharged to the POTW at a sewer charge of $0.10/1,000 gal.
VALUE OF RECYCLED PRODUCT
Recycling waste ink at The Hartford Courant has resulted in savings (or revenue) from
reduced virgin ink and solvent purchases. According to the Courant, for every 200 gal of waste
ink generated, 120 gal of ink and 12 gal of solvent are reclaimed. The Courant generates
9,100 gal of waste ink per year, therefore, 5,460 gal of ink and 546 gal of solvent are reclaimed.
28
-------
TABLE 11. MAJOR OPERATING COSTS
Item
Quantity /Yr.
Unit Cost ($)
Total Cost ($/Yr)
Former Practice
Disposal:
Waste Ink
Drums
Current Practice
Disposal:
Water disposal
Residue disposal
Drums
Recycling:
Electricity
Gas
Labor
9,100 gal
165
200/55 gal drum
30
33,100
4.950
Total 38,050
3,049 gal
46 gal
1
59 batches
59 batches
59 hrs
0.10/1,000 gal
250/55 gal
30
75.62/batch
29.70/batch
10.00/hr
negligible
250
30
: 4,462
I 1,752
i 590
Total 7,084
29
-------
the Courant currently pays $3.32/gal for virgin ink and $2.95/gal for new solvent.
The resulting savings are equal to $18,127/year of ink value and $1,611/year of solvent value, or a
total of $19,738/year. ' . I
PAYBACK - - PRELIMINARY ESTIMATE
A simple payback period calculation can be performed with just the major operating
costs in Table 11.
Payback period (in years) = (Purchase Cost)
(Annual Reduction in Operating Cost) + (Annual Value of Recycled Product)
The purchased cost of the unit is $318,000 including installation. The reduction in
major operating costs can be obtained from Table 11 as $30,966/year. The value of the recovered
ink and solvent is $19,738/year. A simple payback calculation results in a payback period of 7
years. This simple payback calculation is presented as a rough estimate of how long it would take
to recover the investment. It does not include inflationary costs, tax rates, maintenance, etc. A
more through payback calculation is presented in the following text.
ECONOMIC ANALYSIS
The return on investment and payback period for recycling were based on the
worksheets provided in the Waste Minimization Opportunity Assessment Manual (U.S. EPA, 1988).
Capital Costs
Table 12 provides the capital cost inputs used in the worksheet. j
Equipment costs are $318,000, which includes installation, and modifications to
the room where the equipment is stored.
« Installation costs are included above. :
Plant engineering.costs are included above.
Contingency costs are assumed to be $500. ;
Working capital is negligible. -
30
-------
TABLE 12, CAPITAL COSTS FOR THE ECONOMICS WORKSHEET
INPUT
Capital Cost
Capital Cost
Equipment
Materials (inct.)
.Installation fmcl.)
Plant Engineering
Contractor/Engineering
Permitting Costs
Contingency
Working Capital
Start-up Costs
% Equity
% Debt
Interest Rate on Debt, %
Debt Repayment, years
Depreciation period
Income Tax Rate, %
. .. _. . .
Escalation Rates, %
Cost of Capital
$318,000
$0
$0
$0
$0
$1.000
$500
$0
$1,200
100%
0%
0.00%
0
7
43.00%
5.0%
. 15.00%
,
OUTPUT
CAPITAL REQUIREMENT
Construction Year
Capital Expenditures
Equipment
Materials
Installation
Plant Engineering
Contractor/Engineering
Permitting Costs
Contingency
Start-up Costs
Depreciable Capital
Working Capital
Subtotal
Interest on Debt
Total Capital Requirement
Equity Investment
Debt Principal
Interest on Debt
Total Financing
1
$318,000
$0
$0
$0
$0
$1,000
$500
$1,200
$320,700
$0
$320,700
$0
$320,700
$320,700
$0
$0
$320,700
-------
Start-up costs are based on 40 hours of operator time.
100% equity is assumed, that is, The Hartford Courant self-financed the unit. If a
loan were taken, the percent debt and interest rate would have been entered here.
The tax rate is based on The Hartford Courant's rate of 43%.
Escalation (inflation) rate is assumed to be 5%.
Operating Cost/Revenue
Table 13 provides the operating cost/revenue inputs used. i
No raw materials are needed for this process.
Utility costs are based on the energy and gas costs in Table 11
1 hour per batch of additional labor was needed for recycling (as compared to
disposal).
Operating supply costs are based on the miscellaneous solvents and rags.
Maintenance costs are based on a percentage of capital costs.
Overhead costs are based on supervision costs (10% of O&M labor costs), plant
overhead (25% of O&M labor and supervision), and labor burden (28% of O&M
labor and supervision).
Revenue is based.on the value of the recycled ink and solvent as discussed in
Section 4.2.
Results of Economic Analysis
Tables 14 and 15 indicate the results of the economic analysis. A return on
investment is obtained in the tenth year of recycling. A firm that has a cost of capital of 9% or
less would find this investment economical. :
ECONOMIC ASSESSMENT
i
The recycling equipment is a large investment, even for a medium- to large-size
newspaper such as the Courant. At a payback period of ten years or more, this system could be
32
-------
TABLE 13. ANNUAL OPERATING COST/REVENUE INPUTS TO THE ECONOMICS WORKSHEET
GO
Operating Cost/Revenue
Marketable By-products
Recycled Ink
Recycled Solvent
Total $/yr.
Utilities
Gas
Electric
Total $/yr.
Raw Materials
Total, $/yr.
Waste Disposal Savings
Offsite Fees, $
Storage Drums $
Total Disposal Savings
--- - -
$18,127
$1,611
$19,738
$1,752
$4,462
$6,214
$0
$32,850
$4,920
$37,770
Operating Labor
Operator hrs/batch
Batches/year
Wage rate, $/hr.
Operating Supplies
Total $/yr.
Maintenance Costs
(% of Capital Costs)
Labor
Materials
Supervision
(% of O&M Labor)
Overhead Costs
(% of O&M Labor + SupJ
Plant Overhead
Home Office
Labor Burden
1
59
$10.00
10
$10
0.50%
0.50%
10.0%
r.)
25.0%
0.0%
-28.0%
-------
TABLE 14. INCREASED ANNUAL REVENUES AND OPERAT.NG SAVINGS FROM RECYCLING
CJ
REVENUE AND COST FACTORS
Operating Year Number
Escalation Factor
INCREASED REVENUES
increased Production
Marketable By-products
Annual Revenue
1.000
1
1.050
$0
$20,725
$20,725
2
1.103
$0
$21,761
$21,761
OPERATING SAVINGS (Numbers in parentheses indicate net expense)
Raw Materials
Disposal Costs
Maintenance Labor
Maintenance Supplies
Operating Labor
Operating Supplies
Utilities
Supervision
Labor Burden
Plant Overhead
Home Office Overhead
Total Operating Savings
,
- --'- --
*» "
$0
$39,659
($1,670)
($1.670)
($620)
($11)
($6,525)
($229)
($705)
($629)
$0
$27,601
$0
$41,641
($1,753)
($1,753)
($650)
($11)
^$6,851J
($240)
($740)
($661)
$0
- $28,981
-------
TABLE 15. RETURN ON INVESTMENT IRQI)
RETURN ON INVESTMENT
.
Construction Year
Operating Year
Book Value
Depreciation (by straight- line)
Depreciation (by double DB)
Depreciation
Cash Flows
Construction Year
Operating Year
Revenues
+ Operating Savings
Net Revenues
- Depreciation
Taxable Income
- Income Tax
Profit after Tax
+ Depreciation
After-Tax Cash Flow
Cash Flow for ROI
Net Present Value
Return on Investment
1
$320,700
1
($320,700;
($320,700)
1
$229,071
$45,814
$91,629
$91,629
1
$20,725
$27,601
$48,326
$91,629
($43,302)
($18,620)
($24,682)
$91,629
$66,946
$66,946
($262,486)
-79.12%
2
$163,622
$45,814
$65,449
$65,449
2
$21,761
$28,981
$50,743
$65,449
($14,706
($6,324)
($8,383)
$65,449
$57,066
$57,066
($219,335)
-46.11%
3
$116,873
$45,814
$46,749
$46,749
3
$22,849
$30,431
$53,280
$46,749
$6,530
$2,808
$3,722
$46,749
$50,472
$50,472
($186,150)
-26.16%
4
$71,059
$45,814
$33,392
$45,814
4
$23,992
$31,952
$55,944
$45,814
$10,129
$4,356
$5,774
$45,814
$51,588
$51,588
($156,654)
-13.18%
_,
5
$25,245
$45,814
$20,303
$45,814
5
$25,191
$33,550
$58,741
$45,814
$12,927
$5,558
$7,368
$45,814
$53,182
$53,182
($130,213)
-4.61%
01
(Continued)
-------
TABLE 15. (Continued)
RETURN ON INVESTMENT
Construction Year
Operating Year
Book Value
Depreciation (by straight -line)
Depreciation (by double DB)
Depreciation
Cash Flows
Construction Year
Operating Year
Revenues
+ Operating Savings
Net Revenues
- Depreciation
Taxable Income
- Income Tax
Profit after Tax
+ Depreciation
After-Tax Cash Flow
Cash Flow for ROI
Net Present Value
Return on Investment
6
$0
$45,814
$7,213
$25,245
6
$26,451
$35,227
$61,678
$25,245
$36,433
$15,666
$20,767
$25,245
$46,012
$46,012
($110,321)
0.43%
7
$0
$0
$0
$0
7
$27,773
$36,989
$64,762
$0
$64,762
$27,848
$36,914
$0
$36,914
$36,914
($96,443)
3.41%
8
$0
$0
$0
$0
8
$29,162
$38,838
$68,000
$0
$68,000
$29,240
$38,760
$0
$38,760
$38,760
($83,773)
5.79%
9
$0
$0
$0
$0
9
$30,620
$40,780
$71,400
$0
$71,400
$30,702
$40,698
$0
$40,698
$40,698
($72,204)
7.69%
10
$0
$0
$0
$0
10
$32,151
$42,819
$74,970
$0
$74,970
$32,237
$42,733
$0
$42,733
$42,733
($61,641!
9.21%
to
o>
-------
very expensive for smaller printers. However, smaller modules with similar capabilities are
commercially available and could be considered by smaller newspapers. Also, as the cost of
disposal continues to grow (as indicated by current trends) and issues of long-term liability assume
greater importance, the economic attractiveness of this system can be expected to increase.
37
-------
SECTION 5
QUALITY ASSURANCE
A Quality Assurance Project Plan (QAPjP) was prepared and approved by the EPA
before testing began (Battelle 1991). This QAPjP contains a detailed design for conducting this
study. The experimental design, field testing procedures, and laboratory analytical procedures are
covered. The QA objectives outlined in this QAPjP are discussed below.
ON-SITE TESTING
On-site testing was conducted as planned in the QAPjP, which the following
variations. Two samples of the wastewater from the separator were collected and analyzed
instead of the one sample planned because the capacity of the separator tank is smaller than the
amount of water that comes out as distillate. During processing, the tank was filled while more
distillate was being generated. The contents of the separator tank were emptied to make room for
fresh distillate. Because the fresh distillate may be of a different composition than the first
distillate, the original contents of the tank as well as the fresh distillate were sampled for chemical
analysis. -
LABORATORY ANALYSIS
All analyses were performed as planned, except that a duplicate analysis for oil and
grease in the wastewater samples could not be performed because the laboratory;was unable to
conserve enough sample volume for a second analysis. Also some tests, i.e., viscosity, grind,
residue, and water pickup, could not be performed on the waste ink samples because the large
amount of water present in the samples tended to split off into a separate phase.
Grind test results were reported as the mean of readings from four paths. Tack results
were reported as the average of two determinations. All aquatic toxicity tests were conducted
with at least one replicate for each dilution.
38
-------
Table 16 lists the precision data for the chemical analysis of the wastewater. All
precision data were in the acceptable range (_+. 25% precision). Table 17 lists the accuracy data
for the chemical analysis. All matrix spike recoveries were in the acceptable range (75% to 125%
recovery).
LIMITATIONS AND QUALIFICATIONS
Based on the above QA data, the results of the on-site and laboratory testing can be
considered as a valid basis for drawing conclusions about product quality and waste reduction.
Data for economic analysis were obtained primarily from records kept by the Courant. Any
assumptions made are specified so that the readers can adjust them to their own,case.
TABLE 16. PRECISION DATA FOR METALS ANALYSIS '
Parameter
Cadmium
Chromium
Copper
Lead
Nickel
Zinc
Sample
No.
HC2WW
HC2WW
HC2WW
HC2WW
HC2WW
HC2WW
Regular
Sample
<4.1
<4.4
661.8
17.3
<3.4
42,3
Duplicate
<4.1
<4.4
700.5
15.1
<3.4
39,7
Precision*
<%)
NC
NC
5.7
13.6
NC
6.3
a NC =. Not Calculable.
39
-------
. TABLE 17. ACCURACY DATA FOR WASTEWATER ANALYSES
Parameter
Oil & Grease
Total Hydrocarbons
Benzene
Toluene
Chlorobenzene
Cadmium
Chromium
Copper
Lead
Nickel
Zinc
Sample
No.
HC-2-WW
HC-2-WW
HC-1-BL
HC-1-BL
HC-1-BL
HC-2-WW
'- HC-2-WW
HC-2-WW
HC-2-WW
HC-2-WW
HC-2-WW
Regular
Sample
(mg/L)
31.5
56.9
<2.5
<2.5
<2.5
<4.1
<4.4
661.8
17.3
<3.4
42.3
Matrix
Spike Level
(mg/L)
25
50
50
50
50
500
500
500
500
500
500
Matrix Spike
Measured
(mg/L) '
59.4
111.9 :
41.57
39.32
38.82
446.5
424.7 i
1,069 j
420.5
425.3
458.2
Accuracy
%
Recovered
112
110
83
79
78
89
85
81
81
85
83
40
-------
SECTION 6
CONCLUSIONS AND DISCUSSION
The ink recycling system installed at The Hartford Courant newspaper succeeded in
restoring the waste ink to a satisfactory quality. The recycled ink (processed waste ink blended
with virgin ink) fared well in laboratory performance tests, including viscosity, grind, residue, tack,
tinting strength, water content, and water pickup. In most of the tests, there was no noticeable
difference between the performance of the recycled and virgin inks. When the same newspaper
pages were printed first with virgin ink and then with recycled ink, viewers experienced with
printed materials could not tell the difference with respect to glossiness, smoothness, opacity, rub
resistance, tone, absorption/bleed-through, and sharpness, Densitometer measurements taken on
the black image areas on the newspapers, showed that both recycled and virgin inks produced the
same uniform layer on the newsprint. j
The ink going to waste can be virtually eliminated by recycling. Over 99% of the ink
in the waste can be recovered. A small fraction sticks to the paper-dust residue on the filters and
has to be disposed. The blanket wash solvent in the waste-can be recovered and reused. The
wastewater (generated from the fountain solution component of the waste) contains some levels of
contaminants that make it toxic. However, the small volume of this wastewater (254 gal/month)
should not be a problem for a POTW. Nevertheless, it may be desirable from a resource recovery
standpoint, to treat this water on-site by an activated carbon filter and reuse it.
Economic incentive for recycling is the value of the ink and solvent recovered, as well
as reduced disposal costs and potentially reduced liabilities through direct control over potentially
hazardous waste. The payback period for the recycling system at the Courant was 10 years.
According to preliminary data published by the American Newspaper Publishers
Association (ANPA 1991), there are 49 daily newspapers with circulation above 250,000, 96
dailies with circulation between 100,000 to 250,000, and 1,466 dailies with circulation below
100,000, The Courant has a daily circulation of 225,000 and can be considered as a medium-
sized newspaper. A much smaller recycling system than the one installed at the Courant would be
required for smaller newspapers. The technology (distillation and filtration) used at the Courant is
fairly straightforward, and smaller scale units can be assembled. Several smaller vacuum
41 ;
-------
distillation batch stills are commercially available at much lower cost. Some smaller newspapers
have designed their own reclamation systems, essentially filtration units (Rosenberg 1988).
Another option for smaller newspapers is to utilize the services of a mobile truck-mounted recycling
system that goes from site to site and recycles waste ink for a charge. One such mobile unit is
being operated by a vendor in California. The advantage of this system is that the generator does
not have to invest in capital equipment. Potential savings by recycling exist even! for generators
that produce a single drum (or less) of waste ink per month. !
Two types of recycling systems are commercially available. One is the distillation type
at the Courant. The other is the filtration type. Depending on the operation of the presses, the
blanket wash solvent and fountain solution can be segregated from the rest of the waste ink. In
that case, the only contaminant in the waste ink is the paper dust, which can be removed by
filtration making distillation unnecessary. Some printers have been able to recycle waste ink just
by blending it with virgin ink and reusing it (Cross 1989). Besides newspapers, other printers (e.g.,
advertising companies) may be able to use similar technologies.
42
-------
SECTION 7
REFERENCES
American Newspaper Publishers Association (ANPA). Facts About Newspapers. Washington, D.C.
April 1991. ;
Battelle. Quality Assurance Project Plan (QAPiP) for a Waste Ink Recycling Study. Columbus,
Ohio, 1991.
Cross, Lisa. "Ink Waste Disposal". Graphic Arts Monthly. May 1989, pp. 118-120.
Hollander, M, and Wolfe, DA. Nonparametric Statistical Methods. 1973.
New York: John Wiley & Sons.
Rosenberg, J. "Ink Reclamation by Newspapers is Catching On". Editor & Publisher. October 29,
1988, p. 37. i
U.S. EPA. Waste Minimization Opportunity Assessment Manual. July 1988. EPA/625/7-88/003.
43
-------
APPENDIX A
DESCRIPTION OF PRINTING PROCESSES
Printing processes can be classified into four main categories: relief (letterpress and
flexographic), gravure (intaglio), stencil or porous (screen) and planography (lithography). Relief
printing involves image carriers in which the printing image is raised above the carrier. Ink is
applied only to this raised surface and then transferred to the paper or other medium. The gravure
carrier is the reverse of the relief, in that the printing image is recessed, usually to different depths.
Ink is applied to the whole carrier and then removed from the top surface, before being transferred
to the paper. Stencil printing uses porous carriers (silk or steel screens) and the ink flows through
the carrier to the paper. The image is determined by controlling the porosity of different areas of
the carrier. The process which we are most concerned with for this project is planography, which
is described in more detail in the following paragraphs.
In planoaraphv the carrier is generally a flat surface which is divided into areas that
attract oil (hydrophobic), and areas that repel oil (hydrophilic). The ink adheres to those surfaces
that are hydrophobic. A slightly acidic water-based fountain solution, which adheres to the
hydrophilic surfaces, is applied before inking. i
The planographic printing process can be divided into four separate methods: stone
lithography, direct lithography, offset lithography, and collotype. Of these, offset lithography is the
mosit widely used, and is shown in Figure A-1. The printed image on the metal plate cylinder is
transferred (offset) to an offset cylinder that transfers the image to the paper. The offset cylinder
is a rubber-covered blanket cylinder which is better able to conform to the irregularities in the paper
surface than the metal cylinder. The use of the offset cylinder also results in a thinner ink film
applied to the paper and therefore the speed of drying is increased. Trays are placed beneath the
cylinders to collect excess ink, fountain solution, solvent, and paper dust. The cpntents of these
trays constitute the waste ink. |
44
-------
Ink Reservoir
. Fountain
Solution
/Plata
( (Printing)
V Cylinder
/ Offset
/ (Transfer)
I Blanket
A Cylinder
Figure A. Offset Planographic (Lithographic) Printing
45
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-APPENDIX B
DESCRIPTION OF PRINTING INKS
Inks vary according to the printing process, the consistency required, the kind of
paper, the kind of drying, and other printing qualities required. Often, printing inks are classified as
oil or paste inks and solvent or liquid inks. Lithographic and letterpress processes use oil or paste
inks and flexographic and rotogravure processes use solvent or liquid inks. The focus will be on
those inks used in the newspaper industry for offset lithographic printing (described in A.1).
In the lithographic process the ink comes in contact with a water-based fountain
solution. The ink should not mix with, or become emulsified in this solution. This is prevented by
using a water-insoluble ink with high viscosity. In offset printing the ink is transferred to the paper
by way of an intermediate cylinder, therefore the ink is thinned out. For this reason, the
concentration of the coloring matter needs to be increased to maintain a dark print.
Ink is composed of a coloring matter and a vehicle. The coloring matter in most
commercial inks is a dry pigment dispersed in the vehicle. Besides being responsible for the color
of the ink, the pigment also affects properties of viscosity, drying, useful life of printed material,
and chemical resistance. In the lithographic process, the pigment must not be able to bleed in the
water solution.
Pigments are grouped as organic and inorganic. Organic pigments can be in the form
of toners, that are insoluble in pure form or in the form of lakes, which require a metal or inorganic
base for precipitation. Organic pigments can be divided into six categories: 1) Azo insoluble which
are insoluble in water (toluidine, para-chlorinated nitroanalines, naphthol reds, Hansa, benzidine and
dinitroanaline orange). 2) Acid-azo which contain acid groups (lithol, tartrazine, red lake C, Persian
orange). 3) Anthraquinone (alizarine, madder lake, indathrene, vat colors). 4) Indigoid (Indigo blue
and maroons). 5) Phthalocyanine (phthalocyanine green and blue) 6) Basic { PMA, PTA-PMA and
PTA toners and lakes, rhodamine, malachite green, methyl violet, Victoria blue). (Kent, 1983)
Inorganic pigments include the following: all white, some colors, black, extenders, and
metallic pigments. The pigment compounds include zinc oxides, barytes, iron oxides, lead and zinc
chromates, redt lead^ chromium oxides, and nickel titanate. Though there is a variety of compounds
used in pigments, the most commpn in the newspaper industry is carbon black, an organic
pigment. Carbon black yields the blackest color of the pigments, and has the highest tinting
strength and opacity. :
46
-------
The pigment is combined with a vehicle, which usually acts to bind the pigment to the
paper. The vehicle contributes properties of glossiness, wear resistance, and drying qualities such
as type and speed of drying. Linseed oil in an aliphatic hydrocarbon solvent, is a common vehicle
used in lithographic printing. A solvent is used to reduce the viscosity of the ink and then
evaporate off after application. In determining the vehicle for lithographic printing the type of press
used must be considered. There are sheet-fed and web-fed presses. Web-offset presses operate
at higher linear printing speeds and therefore a lower ink tack or "stickiness" should be used.
The resulting waste ink from the printing process will not only contain the ink but also
the fountain solution, solvents and other additives. These must be considered in the recycling
process. The fountain solution is a slightly acidic water-based solution. Solvents are either
hydrocarbon solvents, alcohols, or glycols. Other ingredients may include driers, waxes, anti-
oxidants, lubricants, gellants, defoamers and other additives.
47
-------
APPENDIX C
DENSITOMETER TEST DISCUSSION
When considering data from both inks simultaneously, the difference in .average
densitometer readings between wrapper and core pages was not significantly different from zero
(observed difference was -0.0022). However, when observing this difference for the two inks
individually, highly significant differences were noted. The difference in average readings between
wrapper and core for virgin ink was -0.0677, which was significantly different from zero at the
0.0001 significance level. This stated that the readings averaged significantly higher on the core
page than on the wrapper page when virgin ink was used. In contrast, the difference in average
readings between wrapper and core for recycled ink was 0.0633. This difference was also
significantly different from zero at the 0.0001 significance level, but in the opposite direction from
what was observed with the virgin ink. Thus the readings averaged significantly higher on the
wrapper page than on the core page when recycled ink was used. These conclusions indicate that
the type of ink must be considered when comparing densitometer readings for the two page types.
A similar difference in conclusions was observed between printed pages when
i
comparing densitometer readings between the two inks. The difference in average readings
between virgin ink and recycled ink was -0.1044 for the wrapper page, which was significantly
different from zero at the 0.0001 significance level. This result stated that readings for virgin ink
averaged significantly lower then for recycled ink on the wrapper page. In contrast, the difference
in averages was 0.0267 for core page readings, stating that'virgin ink averaged highpr than
recycled ink on the core page. This difference was significantly different from zero Only at the
i
0.0654 significance level. The distinct results between wrapper and core page implies that overall
conclusions on densitometer readings between the two inks cannot be made without considering
the type of printed page. '
The effect on densitometer readings of location on the page was also included in the
analysis of various procedure. However, this effect was not statistically significant. ;
Thus, in summary, densitometer readings were significantly higher for recycled ink
than for virgin ink on the wrapper page. The readings averaged slightly higher for virgin ink than
for recycled ink on the core page, but this difference was only marginally significant.
48
-------
Likewise, the readings were significantly different between the wrapper and the core page, but the
difference depended on the ink used. Significantly higher readings were noted on the wrapper
page when using recycled ink, while significantly higher readings were noted on the core page
when using virgin ink. These findings indicate that statistical conclusions on differences in
densitometer readings between inks cannot be made without considering whether the printed page
is wrapper or core. !
49
-------
APPENDIX D
The Hartford Courant
Ink Recycling System Operating Cost Estimate
item
skid mixer
ink pump
water pump
vacuum pump
blend tank pump
blend tank mixer
day tank pump
chiller
compressor
fan motor
coolant pump
volts
460
460
208
460
460
460
460
460
230
460
phase
3
3
3
3
3
3
3
3
1
3
>er batch at
amps
1.8
1.6
1.8
2.8
6.5
4.5
6.8
6.2
2.9
2.2
$0.08
hours
per
batch
50
2
1
'.' 50
50
25
50
37.5
; 50
50
total
per kwh -
kwh
per
batch
60.9
2.2
0.6
94.8
220.1
76.2
230 . 3
157.5
28.3
74.5
945 . 3
$75.62
gas cost per batch
at
utility cost per batch
P. J. Reynolds 8/16/91
45 ccf per batch
$0.66 per ccf
. $29.70
tsasasas:
$105.32
50
------- |