oEPA
United States
Environmental Protection
Agency
Research and Development
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
EPA/600/S-92/039 Oct. 1992
ENVIRONMENTAL
RESEARCH BRIEF
Waste Reduction Activities and Options for a
Manufacturer of Finished Leather
Patrick Eyraud and Daniel J. Watts*
Abstract
The U.S. Environmental Protection Agency (EPA) funded a
project with the New Jersey Department of Environmental
Protection and Energy (NJDEPE) to assist in conducting waste
minimization assessments at 30 small- to medium-sized busi-
nesses in the state of New Jersey. One of the sites selected
was a manufacturer of finished leather. A site visit was made in
1990 during which several opportunities for waste minimization
were identified. Recommendations included 1) changeover to
water-based coatings; 2) installation of a solvent recovery/
reuse capability; 3) use of a hand pump to reduce spillage
during transfer and physical layout considerations to reduce
the distances materials must be moved; 4) reducing the volume
of the container for test mixes; 5) improvements to the computer-
controlled spray-coating operation to reduce overspray; and 6)
the use of covers over formulated coating mixtures to reduce
air emissions. Implementation of the identified waste minimiza-
tion opportunities was not part of the program. Percent waste
reduction, net annual savings, implementation costs and pay-
back periods were estimated.
This Research Brief was developed by the Principal Investiga-
tors and EPA's Risk Reduction Engineering Laboratory in Cin-
cinnati, OH, to announce key findings of this completed as-
sessment.
Introduction
The environmental issues facing industry today have expanded
considerably beyond traditional concerns. Wastewater, air
emissions, potential soil and groundwater contamination, solid
waste disposal, and employee health and safety have become
increasingly important concerns. The management and dis-
* New Jersey Institute of Technology, Newark, NJ 07102
posal of hazardous substances, including both process-related
wastes and residues from waste treatment, receive significant
attention because of regulation and economics.
As environmental issues have become more complex, the
strategies for waste management and control have become
more systematic and integrated. The positive role of waste
minimization and pollution prevention within industrial operations
at each stage of product life is recognized throughout the
world. An ideal goal is to manufacture products while generat-
ing the least amount of waste possible.
The Hazardous Waste Advisement Program (HWAP) of the
Division of Hazardous Waste Management, NJDEPE, is pursu-
ing the goals of waste minimization awareness and program
implementation in the state. HWAP, with the help of an EPA
grant from the Risk Reduction Engineering Laboratory, con-
ducted an Assessment of Reduction and Recycling Opportuni-
ties for Hazardous Waste (ARROW) project. ARROW was
designed to assess waste minimization potential across a
broad range of New Jersey industries. The project targeted 30
sites to perform waste minimization assessments following the
approach outlined in EPA's Waste Minimization Opportunity
Assessment Manual (EPA/625/7-88/003). Under contract to
NJDEPE, the Hazardous Substance Management Research
Center at NJIT assisted in conducting the assessments. This
research brief presents an assessment of a manufacturer of
finished leather (1 of the 30 assessments performed) and
provides recommendations for waste minimization options re-
sulting from the assessment.
Methodology of Assessments
The assessment process was coordinated by a team of techni-
cal staff from NJIT with experience in process operations,
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basic chemistry, and environmental concerns and needs. Be-
cause the EPA waste minimization manual is designed to be
primarily applied by the inhouse staff of the facility, the degree
of involvement of the NJIT team varied according to the ease
with which the facility staff could apply the manual. In some
cases, NJITs role was to provide advice. In others, NJIT
conducted essentially the entire evaluation.
The goal of the project was to encourage participation in the
assessment process by management and staff at the facility.
To do this, the participants were encouraged to proceed through
the organizational steps outlined in the manual. These steps
can be summarized as follows:
• Obtaining corporate commitment to a waste minimization
initiative
• Organizing a task force or similar group to carry out the
assessment
• Developing a policy statement regarding waste minimiza-
tion for issuance by corporate management
• Establishing tentative waste reduction goals to be achieved
by the program
• Identifying waste-generating sites and processes
• Conducting a detailed site inspection
• Developing a list of options which may lead to the waste
reduction goal
• Formally analyzing the feasibility of the various options
• Measuring the effectiveness of the options and continuing
the assessment.
Not every facility was able to follow these steps as presented.
In each case, however, the identification of waste-generating
sites and processes, detailed site inspections, and development
of options was carried out. Frequently, it was necessary for a
high degree of involvement by NJIT to accomplish these steps.
Two common reasons for needing outside participation were a
shortage of technical staff within the company and a need to
develop an agenda for technical action before corporate com-
mitment and policy statements could be obtained.
It was not a goal of the ARROW project to participate in the
feasibility analysis or implementation steps. However, NJIT
offered to provide advice for feasibility analysis if requested.
In each case, the NJIT team made several site visits to the
facility. Initially, visits were made to explain the EPA manual
and to encourage the facility through the organizational stages.
If delays and complications developed, the team offered assis-
tance in the technical review, inspections, and option develop-
ment.
Facility Background
The plant produces finished leathers which are sold to manu-
facturers of leather goods such as handbags, belts, shoes, and
other items. The operation of the plant varies according to
customer demand. Many different colors, textures, and designs
must be incorporated into the product to meet varying cus-
tomer requirements, forcing the operation of several special
production steps on an irregular basis. The facility formerly
tanned raw hides, but that process has been phased out as a
result of changing supply and market conditions.
Manufacturing Process
This facility receives tanned leather from various sources and
transforms it into a product of higher commercial value by
applying various coatings and other surface modifications to
make it more usable and appropriate for finished consumer
products. The raw materials include, in addition to the leather
itself, various water- and solvent-based coatings as well as
some specialized colorants and other surface modification
products. The solvents in the coatings typically are aromatic
and aliphatic hydrocarbons, esters, and alcohols.
The following processes are carried out in the facility but not
every hide necessarily receives each finishing process.
Back Coating
Base Coating
Plating Top
Tipping (hand made)
Color Top
Clear top
A typical hide in the manufacturing process might receive the
following finishing steps.
Newly received hides are prepared for finishing by washing,
retanning if necessary, and drying. The aqueous wastes from
these steps are sent to the POTW with regular monitoring to
assure compliance.
Some hides undergo surface modification by mechanical buff-
ing. The resulting dust is classified as a hazardous waste and
is disposed of offsite.
The back coating step applies essentially the final finish to the
back of the leather while the base coating of the smooth side
serves as the primer for additional finishes to be applied. The
coatings are applied using an automated spray system. The
facility has shifted largely to water-based coating for these
steps resulting in a significant decrease in solvent use. Any
over-spray is captured by a water-screen or by filters and
disposed of offsite.
The next coating steps are accomplished using solvent-based
materials. No satisfactory non-solvent based coatings have yet
been identified for these finishing steps. The applied finishes
are thermally dried with venting of solvent vapors to the atmo-
sphere.
The final steps in the manufacturing process are ironing, grad-
ing, measuring, and shipping—operations which are not sig-
nificant waste-generating activities.
Existing Waste Management Activities
The facility has shifted to the use of water-based coatings where
possible. Moreover, the technical staff continues to evaluate new
commercial reduced-solvent products in order to make further re-
ductions. An optical/computer interfaced system has been used to
determine the shape and position of each hide presented for coating
which is used to control the automated spray coating system,
resulting in significant reduction of overspray.
Waste Minimization Opportunities
The type of waste currently generated by the plant, the source of the
waste, the quantity of the waste, and the annual treatment and
disposal costs (where known and available) are given in Table 1.
Table 2 presents the opportunities for pollution prevention
which were identified during the assessment. The type of
waste, the minimization opportunity, and the possible waste
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reductions, are presented in the table. When available or esti-
mable, the associated saving, and implementation costs along
with payback times are also given, However, because the
feasibility analysis was to be carried out by the staff of the
facility, that information is not always readily available.
Additional Options Identified
In addition to the options previously discussed two other options
were suggested. It was observed that the wooden pallets and
cardboard used for shipping hides to the facility might have
increased value if recycled. Second, the future use of a spray
coating system based upon supercritical carbon dioxide as a
solvent/carrier was identified. However, such a system depends
not only on the availability of the hardware, but also on the
manufacture of coatings compatible with the spray system and
capable of providing the required quality for the finished leather.
Such coatings are not presently available.
Regulatory Implications
The significant regulatory issue at a facility such as this is the
impending requirement for more efficient air emission control
practices. This concern is driving the interest in pollution pre-
vention. Unfortunately, the apparent best solution—changing to
water based coatings—is not technically feasible. It is unknown
if the perhaps next best solution—solvent capture and recovery
from the process air emissions—would be acceptable to the
regulatory authorities in light of better known thermal oxidation
systems which have less source reduction potential. If a facility
has capital resources to install only one system, it is uncertain
what position and role a regulatory authority will take.
This Research Brief summarizes a part of the work done under
cooperative Agreement No. CR-815165 by the New Jersey
Institute of Technology under the sponsorship of the New
Jersey Department of Environmental Protection and Energy
and the U.S. Environmental Protection Agency. The EPA Project
Officer was Mary Ann Curran. She can be reached at:
Pollution Prevention Research Branch
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
Table 1. Summary of Current Waste Generation
Waste Generated
Washing Waters
Buffing Dust
Evaporated Coating
Source of Waste
Cleaning of
incoming hides
Mechanical abrasion
of hide surface
Application of back
Annual Quantity
Generated
130,000 gal
<100lb
130 tons
Annual
Costs
$30
$325
These are either
Solvent
Solvents and Coatings
coating, base coating,
plating top, color top,
and clear top to hides.
Most solvent evaporation
occurs during oven assisted
drying. Some loss also
occurs as a result of
spills and leaks during
material mixing and trans-
fer.
Excess coatings and solvent
from equipment cleaning
12,300 gal
fugitive emissions
or regulated emissions
to the atmosphere, and
therefore have no management
costs except the loss of
potential recovery value.
$61,000
ft U.S. GOVERNMENT PRINTING OFFICE: 1*94 - 5S0-4M7/MK8
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Table 2. Summary of Waste Minimization Opportunities
Waste Generated Minimization Opportunity
Annual Waste Reduction Net Implementation Payback
Quantity Percent Annual Savings Cost Years*
Buffing Dust
Evaporated Solvent
Solvents and
Coatings
Evaporated Solvent
Sale for beneficial reuse
in resin-based composite
product.
Continue changeover to water
based coatings subject to
development of satisfactory
materials by coating manu-
facturers.
Prepare test formulations in
smaller quantities.
Reprogram automated spray
coating equipment to compensate
for required angle spraying.
100 Ib
1.3 tons
300 Ib
100%
10%
2%
$325
immed
The savings will come from avoided treatment
from an air emissions control system not yet
installed. The facility is clearly dependent
upon the coating production industry and can-
not make progress in this area alone.
$900
immed
up to 65% when
angle spraying is
required.
12.7 tons 9.7%
$25,000 $5,000 0.2
More savings will result from avoided treatment costs
from the new control system not yet installed.
Install covers on coating
reservoir containers during
spray coating operations.
variable depending
upon solvent
volatility
500 Ib 0.2 %
$500
$1,000
2.0
Install solvent capture
system allowing capture
and reuse. Possibilities
include a carbon system
with steam distillation
regeneration capability
permitting recovery of
the captured solvent.
Distillation and reuse
of the solvent is possible
if the solvent mixture is
not too complex. Difficult
mixtures may have to be distilled
offsite where more efficient
columns are available.
up to 90%
depending upon
type of solvent.
117 tons
90%
$200,000
$300,000
1.5
(A system of this type could serve as the emission
control device assuming that the regulatory
authority would approve it instead of more usual
equipment.)
Savings result from reduced raw material, and treatment and disposal costs when implementing each minimization opportunity independently.
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
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EPA
PERMIT No. G-35
EPA/600/S-92/039
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