United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/M-91/025 July 1991
$EPA ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment for a Manufacturer of
Aluminum Cans
F. William Kirsch and Gwen P. Looby*
Abstract
The U.S. Environmental Protection Agency (EPA) has
funded a pilot project to assist small- and medium- size manu-
facturers who want to minimize their generation of hazardous
waste but lack the expertise to do so. Waste Minimization
Assessment Centers (WMACs) were established at selected
universities and procedures were adapted from the EPA Waste
Minimization Opportunity Assessment Manual (EPA/625/7-
88/003, July 1988). The WMACteam at Colorado State Univer-
sity inspected a plant producing more than one billion alumi-
num cans each year for a local beverage producer. After the
cans have been formed, they are cleaned and painted. These
two operations generate the waste: most can cleaning wastes
are treated and sewered, and the hazardous painting and
inking operations' wastes are shipped to a hazardous waste
disposal facility. The on-site treatment facility treats the can
washing effluent so that the oil can be hauled to an oil recycler,
the sludge disposed of off-site, and the clarified liquid dis-
charged to the sewer. Because the plant had already initiated
many steps to minimize and manage its wastes, the WMAC's
team report, detailing theirf indings and recommendations, was
only able to suggest that a nonhazardous reagent be substi-
tuted for the presently used reagent that contains from 2% to
4% ammonium fluozirconate. The can washing sludge would
then be nonhazardous, and all of the hazardous waste disposal
costs could be saved.
This Research Brief was developed by the principal inves-
tigators and EPA's Risk Reduction Engineering Laboratory,
Cincinnati, OH, to announce key findings of an ongoing re-
search project that is fully documented in a separate report of
the same title available from the authors.
Introduction
The amount of hazardous waste generated by industrial
plants has become an increasingly costly problem for manufac-
turers and an additional stress on the environment. One solu-
tion to the problem of hazardous waste is to reduce or eliminate
the waste at its source.
University City Science Center (Philadelphia, PA) has
begun a pilot project to assist small- and medium- size manu-
facturers who want to minimize their formation of hazardous
waste but lack the inhouse expertise to do so. Under agree-
ment with EPA's Risk Reduction Engineering Laboratory, the
Science Center has established three WMACs. This assess-
ment was done by engineering faculty and students at Colorado
State University's (Fort Collins) WMAC. The assessment teams
have considerable direct experience with process operations in
manufacturing plants and also have the knowledge and skills
needed to minimize hazardous waste generation.
The waste minimization assessments are done for small-
and medium-size manufacturers at no out-of-pocket cost to the
client. To qualify for the assessment, each client must fall within
Standard Industrial Classification Code 20-39, have gross
annual sales not exceeding $50 million, employ no more than
500 persons, and lack inhouse expertise in waste minimization.
'University City Science Center, Philadelphia, PA 19104
'A// Printed on Recycled Paper
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The potential benefits of the pilot project include minimiza-
tion of the amount of waste generated by manufacturers, re-
duced waste treatment and disposal costs for participating
plants, valuable experience for graduate and undergraduate
students who participate in the program, and a cleaner environ-
ment without more regulations and higher costs for manufactur-
ers.
Methodology of Assessments
The waste minimization assessments require several site
visits to each client served. In general, the WMACs follow the
procedures outlined in the EPA Waste Minimization Opportu-
nity Assessment Manual (EPA/625/7- 88/003, July 1988). The
WMAC staff locates the sources of hazardous waste in the plant
and identifies the current disposal or treatment methods and
their associated costs. They then identify and analyze a variety
of ways to reduce or eliminate the waste. Specific measures to
achieve that goal are recommended and the essential support-
ing technological and economic information is developed. Fi-
nally, a confidential report that details the WMAC's findings and
recommendations (including cost savings, implementation costs,
and payback times) is prepared for each client.
Plant Background
The plant evaluated for this waste minimization assess-
ment produces 12-ounce aluminum cans for a local beverage
producer. It operates 24 hr/day, 7 day/wk, virtually year-round to
produce more than one billion cans annually. The facility oper-
ates two identical process lines.
Manufacturing Process
Aluminum coil stock is the major raw material used to
manufacture aluminum beverage cans.
The aluminum coils are placed onto spools feeding the
cupper machines. As the coils are unwound, they pass through
a lubricator. Lubricating the aluminum protects the dies in the
cupper machines. The aluminum is hydraulically pushed into the
cup dies to produce cups. The cups are then fed into extruders
where a ram pushes the cups through dies to form can bodies.
After the cans leave the extruders, they are trimmed to the
proper depth. A pneumatic conveyor system then moves the
cans from the extruders through automated spray- washing
machines.
The can washing process consists of a pre-wash, a wash,
a rinse, a treatment stage, a city-water rinse, and a deionized
water rinse. Incoming city water enters the process at the city-
water rinse stage and flows in a countercurrent direction through
the rinse and pre-wash stages. Spent rinse water flows to the on-
site wastewater treatment facility, which will be discussed be-
low.
Proprietary reagents containing sulfuric acid and hydroflu-
oric acid are added to water in the wash stage to clean the inner
surfaces of the cans. A proprietary reagent that contains nitric
acid, hydrofluoric acid, and ammonium f luozirconate is added to
water in the treatment stage to provide smooth inner can
surfaces.
The final, closed-bop rinse of deionized water removes
mineral residues left by the city water. After the rinse, the
contaminated water is pumped through activated carbon ad-
sorption filters and an ion exchange unit. The anion and cation
exchange resins are regenerated about every 1-1/2 months
using hydrochloric acid and sodium hydroxide. Effluent from
resin regeneration is neutralized separately from the remainder
of the wastewater and discharged to the sewer. The carbon
filters are backwashed when the pressure drop across the filters
reaches about 6 psi. The backwash is neutralized with the resin
regeneration effluent and discharged to the sewer.
The cans are dried in gas-fired drying ovens at a tempera-
ture of 106°F. A base coat of paint is then applied to the outside
of the cans and is dried in a gas-fired oven. Next, the customer's
insignia is printed on the outside of the cans with ink; the cans
are dried again after printing. A final coat of clear lacquer is
applied to the outer can surface. The inside surfaces of the cans
are painted with a water-based vinyl coating. A final 30 sec
drying stage at 385°F serves as a final cure for all coats of paint.
Liquid hazardous wastes are generated from the painting
and inking operations in the form of excess paint and ink cleaned
from machinery. Most of the paint wastes are from the water-
based paint used to coat the inner can surfaces. Although the
paints and inks are water-based, they contain ethylene glycol
monobutyl ether, n-butyl alcohol, dimethylethanolamine, and 2-
butoxyethanol; the paint wastes are considered hazardous and
are shipped to a hazardous waste disposal facility.
Af langing process is used to provide the cans with a necked
top. The finished cans are inspected, palletized, and stored in
the warehouse to await shipping.
Wastewater from the various stages of the can washer
flows to a series of overflowing tanks for the initial stages of
treatment. In the first tank, ferric chloride is added, and the pH
is adjusted to less than 3 with sulf uric acid. The second tank
contains an absorbent cloth oil skimmer that generally operates
for 15 min/hr. The oil that is recovered flows to a 10,000-gal split
tank. Sulf uric acid is added to that tank to lower the pH to 4 and
to break most of the oil-water emulsion that forms. The remain-
ing emulsion is de- emulsified by heating to 160°F. Waste oil is
collected in a storage tank and is periodically hauled to an oil
recycler who filters and distills the used oil and sells the product
as industrial fuel.
Lime is added in the third tank to raise the pH to about 9 and
to precipitate aluminum hydroxide, calcium fluoride, calcium
sulfate, ferric hydroxide, and magnesium hydroxide from the
wastewater. The fourth tank is an overflow tank for the precipi-
tates and supernatant. A polymer is added in that fourth tank to
flocculate the solids and clarify the liquid.
The effluent from the fourth tank flows to the center of a
large clarifier. Flocculated solids settle to the bottom of the
clarifier and form a sludge. The clarified liquid meets the effluent
limits set by the local publicly owned treatment works (POTW)
and is discharged to the sewer.
Sludge is periodically pumped from the bottom of the
clarifier to a storage tank. A pump transfers the sludge to a filter
press to remove excess water before shipping and disposal. The
sludge from the filter press contains about 67% solids by weight.
Existing Waste Management Practices
Before the WMAC team's assessment, this plant had taken
the following steps to minimize and manage its hazardous
wastes:
collects scrap aluminum for recycling;
has reduced water use in the can wash ing operation
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to the lowest possible rate;
has reduced the concentrations of chemicals used
in the can washing operations to the bwest possible
values;
uses a filter press to reduce the water content of
hazardous sludge before shipment off-site for
disposal; and
has an oil recycler collect waste oil from the
extruder coolant system.
Waste Generation
Most of the hazardous waste generated by this plant comes
from the can washing operation. Water laden with oil, hydroflu-
oric acid, sulfuric acid, nitric acid, and ammonium fluozirconate
is treated on-site and discharged to the sewer. Sludge contain-
ing calcium fluoride, calcium sulfate, magnesium suffate. and
ammonium fluozirconate is precipitated from the rinse water
treatment process and hauled off-site for disposal.
Liquid hazardous wastes are generated by the painting and
inking lines.
Table 1 summarizes the principal sources of waste, their
amounts, and the treatment and disposal costs.
Summary of Recommended Waste Minimization
Table 2 briefly describes the current plant practice, the
recommended waste minimization opportunity (WMO), and
savings and cost data.
This Research Brief summarizes a part of the work done
under Cooperative Agreement No. CR-814903 by the University
City Science Center under the sponsorship of the U.S. Environ-
mental Protection Agency. The EPA Project Officer was Brian A.
Westfall.
The EPA contact, Emma L. George, 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 Source of Waste
Tap-water rinses
Paint wastes
Sludge
Can washer
Painting line
Waste water treatment
Annual Quantity Annual Waste Manaaement Costs
Generated Treatment
30,699,000 gal $55,000
5,400 gal
888,300 Ib
Disposal
$11,850
35.200
147,800
Table 2. Summary of Recommended Waste Minimization Opportunity
Present Practice
Proposed Action
Waste Reduction and Associated Savings
The reagent used to treat the
surface of the cans contains 2%
to 4% ammonium fluozirconate.
Substitute a nonhazardous reagent that
contains nitric acid and hydrofluoric acid
for the hazardous reagent currently used.
Replacing the present reagent with one that
will not produce a hazardous sludge will
eliminate the need for disposal at a
hazardous waste disposal facility. There is
no cost difference between these two reagents.
Waste reduction = 888,300 Ib
Cost reduction = $133,060
Implementation cost = $0
Payback is immediate.
•A-U.S. GOVERNMENT PRINTING OFFICE: 1994 • 55O-067/JWI7I
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United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
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EPA/600/M-91/025
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