United States
                         Environmental Protection
                                     Risk Reduction
                                     Engineering Laboratory
                                     Cincinnati OH 45268
                         Research and Development
                                    EPA/600/S-92/019 May 1992
                         Waste Minimization Assessment for a
                     Manufacturer of Metal-Plated Display Racks

                               Gwen P. Looby and F. William Kirsch*
The U.S. Environmental Protection Agency (EPA) has funded a
pilot project to assist small- and medium-size manufacturers
who want to minimize their generation of waste but who lack the
expertise to do so. Waste  Minimization  Assessment Centers
(WMACs) were established  at selected universities and proce-
dures were adapted from the EPA Wasfe Minimization Opportu-
nity Assessment Manual (EPA/625/7-88/003, July 1988). The
WMAC team at the University of  Tennessee performed  an
assessment at a plant manufacturing metal-plated display racks.
Steel wire, tubing,  and sheets undergo machining operations,
and the resulting parts are then nickel and brass-plated, nickel-
plated, zinc-plated, nickel and chrome-plated, or painted. The
various finished parts are assembled  into display racks. The
team's report, detailing findings  and  recommendations, indi-
cated that the majority of waste was generated by the plating
lines and that the  greatest  waste reduction would result from
utilizing a Zero Discharge Recovery system in the nickel-plating

This Research Brief was developed by the principal investiga-
tors and EPA's Risk Reduction Engineering Laboratory, Cincin-
nati, OH, to announce key findings of an ongoing research
project that is fully documented in a separate report of the same
title available from the authors.

The amount of waste generated by industrial plants has be-
come an increasingly costly problem for manufacturers and an
additional stress on the environment. One solution to the prob-
lem of 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 manufacturers
who want to minimize their formation of waste but who lack the
                        in-house expertise to do so. Under agreement with EPA's Risk
                        Reduction Engineering Laboratory, the Science Center has es-
                        tablished three WMACs. This assessment was done by engi-
                        neering faculty and students at the University of Tennessee's
                        (Knoxville) WMAC. The assessment teams have considerable
                        direct experience with process operations in manufacturing plants
                        and also have the knowledge and skills needed to minimize
                        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 an-
                        nual sales not exceeding $50 million, employ no more than 500
                        persons, and lack  in-house expertise in waste minimization.

                        The potential benefits of the pilot project include minimization of
                        the amount  of  waste generated  by manufacturers, reduced
                        waste treatment and disposal costs  for participating plants,
                        valuable experience for graduate and undergraduate students
                        who  participate in the program,  and a cleaner environment
                        without more regulations and higher costs for manufacturers.

                        Methodology of Assessments
                        The waste minimization assessments require several site visits
                        to each client served. In general, the WMACs follow the proce-
                        dures outlined in the EPA Waste Minimization Opportunity As-
                        sessment Manual (EPA/625/7-88/003, July  1988). The WMAC
                        staff locates the sources of 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 supporting tech-
                        nological and economic information is  developed.  Finally,  a
                        confidential report that details the WMAC's findings and recom-

mandations (Including cost savings, implementation costs, and
payback times) is prepared for each client.

Plant Background
This plant manufactures metal-plated display racks. The plant's
200 employees process approximately ten million Ibs of metal
annually and operate the plant 4,160 hr/yr.

Manufacturing Process
        Raw materials for the display racks include steel wire,
tubing,  and sheets; nickel,  zinc, and  brass plating anodes;
cleaning agents and  plating  solution chemicals;  and powder
and liquid paints. Approximately 40% of the finished products
are nickel and brass-plated,  26%  are  nickel-plated,  24%  are
zinc-plated, and 10% are nickel and chrome-plated.

The steel wire, tubing, and sheets undergo stamping, bending,
forming, shaping, welding, and riveting. The parts to be plated
are then sent  through one of the three following plating lines.
Other parts are sent to the paint line, which is also described

Barrel Plating Line
Smalt fabricated parts are cleaned  prior  to plating to remove
residual oils and grease by using either a vibrating cleaning unit
or a rotating  abrasive tub. The vibrating tub cleans parts by
Vibrating them In  a chemical  solution. Spent cleaning solution
and rinse water are sent  to the plant's wastewater treatment
facility.  In the other method, the parts and abrasive pellets are
placed  in small rotating tubs for cleaning. Spent abrasive is
disposed of In a landfill.

The cleaned parts are placed in hollow barrels which are at-
tached  to an  overhead  conveyor system. The  barrels,  which
have holes along the length of their surfaces, are slowly rotated
while being submerged for a specified amount of time  in the
various tanks of the plating line.

Each batch of  parts to be plated undergoes specific steps in the
line. All of the pieces pass through most of the same prepara-
tory stages, while later stages in the line are reserved for one
type of plated part only. Spent solutions from all tanks except
the plating baths are dumped to the plant's wastewater treat-
ment facility.  Plated parts are then  sent to other  areas  of the
plant for assembly.

Zinc Plating  Line
Larger-sized metal pieces are manually  hung on  racks attached
to an overhead conveyor system which is used to dip parts in
the 22 tanks of the line. All spent tank solutions are piped to the
plant's  wastewater treatment facility.  Plated  parts are  trans-
ferred to the assembly areas of the plant.

Frame Plating Line
The frame plating line is used to plate nickel, nickel and chrome,
and nickel and brass  onto large display rack frames.  Parts are
hung on racks as In the zinc-plating line; some tanks in this line
are bypassed  depending on which type of  plating is required.
Spent tank solutions  are sent to the plant's wastewater treat-
ment facility.  Finished parts  are transferred to the assembly
areas of the plant.
Paint Line                           ;
Miscellaneous metal pieces which do not require plating are
sent to the three-stage washer and paint I areas. The parts are
hung on a small conveyer system which transports them through
an enclosed washer line containing three different solution-filled
tanks.  Spent solutions are dumped directly to the  municipal
sewer.           .                     i

After cleaning and drying,  parts are painted using electrostatic
powder coating  or  liquid  dip painting.  Overspray  powder  is
collected and reused. Drag-out from dip painting is collected on
cardboard or plastic sheets which are disposed of in a landfill.
After drying, the painted parts are transferred to the assembly
areas of the plant.                     :

Existing Waste Minimization Practices

     •   The plant operates an electrostatic powder paint
        system to reduce  the amount of paint wastes it
        generates.                     i

     •   Water-based, nonhazardous liquid paints are used.

     •   Filtering systems  recover zinc and nickel from
        spent plating solutions.         '

        Cyanide-laden brass plating water is stored in a
        holding tank and used as rinse water in several of
        the plating line stages.          i

        All wastewater is  treated onstte before release to
        the municipal sewer.           ;

        A natural gas-fired dryer is used to reduce the
        volume of sludge  resulting from the filter press
Waste Minimization Opportunities
The type of waste currently generated by; the plant, the source
of the waste, the quantity of the waste, jand the annual  treat-
ment and disposal costs are given in Table 1.

Table 2 shows the opportunities for waste, minimization that the
WMAC team recommended for the plant. Jhe type of waste, the
minimization opportunity, the possible waste reduction and as-
sociated savings, and the implementatioh  cost along with the
payback time are given in the table. Thfe quantities  of waste
currently generated by the plant and possible waste reduction
depend on the  production level of the plant. All values should
be considered in that context.           |

It  should be noted that the economic sayings  of the minimiza-
tion opportunity, in most cases, results from the need for less
raw material and from reduced present and future costs associ-
ated with treatment and disposal. Other savings not quantifiable
by this  study include a wide  variety of possible  future  costs
related to changing emissions standards, liability, and employee
health. It should also be noted that the savings given for each
opportunity reflect the savings achievable when implementing
each waste minimization opportunity independently and do not
reflect duplication of savings that would result  when the oppor-
tunities are implemented in a package.

This research brief summarizes a part of the work done under , tal Protection Agency. The EPA Project Officer was Emma Lou
Cooperative Agreement No. CR-814903 by the University City   George.
Science Center under the sponsorship of the U.S. Environmen-
Table 1.  Summary of Current Waste Generation
Waste Stream
Barrel Plating Line
Waste Management Method
Treated onsite and sewered
Annual Quantity
208,000 gal
Annual Waste
Management Cost
     Contaminated wash and rinse water
     from cleaning process

     Spent abrasive from cleaning process

     Contaminated plating, wash, and rinse water

Zinc-Plating Line

     Contaminated plating, wash, and rinse water

Frame Plating Line

     Contaminated plating, wash, and rinse water

Paint Line

     Contaminated wash and rinse water

     Paint overspray on cardboard and plastic
     sheets        •  .



Wastewater Treatment

     Waste solids
Offsite landfill

Treated onsite and sewered

Treated onsite and sewered

Treated onsite and sewered


Offisite landfill

Treated onsite and sewered

Offsite landfill
     6,000 Ib

 817,860 gal

1,201,080 gal

1,067,260 gal

 153,360 gal

     110 gal

 262,000 gal

    4,180 gal







Table 2. Summary of Recommended Waste Minimization Opportunities
Present Practice
                                                    Proposed Action
                                        Waste Reduction and Associated Savings
Contaminated plating, wash, and rinse water from
the barrel, zinc and frame plating lines and
contaminated wash and rinse water from the paint
line are treated onsite and sewered.
As the nickel plating baths in the barrel and frame
plating lines become contaminated, they are emptied
into dedicated filtering units which are used to recover
a large portion of the paniculate nickel in the solutions.
The filtering units are periodically cleaned by back-
flushing with a weak acid solution. The acid solution,
which contains contaminants, is sent to the plant's
waste water treatment facility. Currently, a significant
amount of nickel is discharged in the waste water
sludge which, as a result, is classified as hazardous
   Install a piping system to recycle
   treated waste water within the plant
   to reduce purchases of water.
   If necessary, improve the current
   methods of waste water filtering to
   provide sufficiently clean water.
    Estimated waste reduction = 3,114,290 gal/yr
    Raw material cost savings =$11,120/yr
    Operating cost = $3,840/yr
    Total cost savings = $7,280/yr
    Implementation cost = $56,380/yr
    Simple payback = 7.8 yr
   Modify the plating lines in question to
   incorporated the utilization of a Zero
   Discharge Recovery (ZDR) system.
   It is recommended that the sytem use
   reverse osmosis technology to recover
   plating bath solutions at plant-specific
   concentration levels. The system will
   operate in a closed-loop manner and
   therefore the amount of nickel dishcarged
   to the wastewater treatment facility will
   be reduced. A portion of the  chemicals
   .required by the baths and by the water
   treatment facility will no longer be needed.
   Approximately the same amount of sludge
   will be generated, but it will be classified
   as nonhazardous.
    Estimated waste reduction = none
    Waste disposal cost savings = $24,460/yr
    Raw material cost savings = $6,250/yr
    Operating cost = $8,000/yr
    Total cost savings = $22,710/yr
    Implementation cost = $70,000
    Simple Payback = 3.1 yr
                                                                        •fru.S. GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40267

Tebla 2, Summary of Recommended Waste Minimization Opportunities (concluded)
Present Practice
Proposed Action
Waste Reduction ar\d Associated Savings
Acid wash tanks, which are used in each of the
plating lines for cleaning of metal parts, are
dumped to the waste water treatment facilitiy as
they become contaminated
RJnstog in the plating lines is accomplished by
dipping parts In rinse tanks. As a result,
considerable drag-out and contamination occur.
Spent water from the rinsing tanks is dumped to the
onslta waste water treatment facility, treated, and
released to the municipal sewer.

Drag-out ki the three plating lines currently
accounts for an estimated 10% loss in chemical
 Varotis tanks In the plating and paint lines are
 steam-heated, Condensate is not returned to boiler
 because of concerns about possible contamination;
 it Is sent to the waste water treatment facility.
Recover and reuse the spent salt/
add solution from the contaminated
wash tanks. It is estimated that 70%
of the acid salt can be recovered
using an evaporator and reused.
Implementation of this recommendation
will lead to a reduction in the amount
of acid salt purchases.

Wherever possible, modify the zinc and
frame plating lines to utilize spray rinsing
techniques instead of dipping in tanks.
Install rinse devices above each plating
and wash tank in the zinc and frame plat-
ing lines to spray water on parts as they
are removed from tanks. As a result,
plating solutions will be returned to their
tanks before drag-out occurs.

Install individual heat exhangers to serve
each heated wash tank and plating bath.
The proposed units should transfer heat
from the main steam line to smaller lines
feeding each  tank. Therefore, the steam
will not come in contact with any process
fluids and can be returned to the boiler.
Estimated waste reduction = 42 gal/yr
    (waste solids) + 30,860 gal/yr water
Waste management cost savings = $390/yr
Rasw material cost savings =$7,700/yr
Total cost savings = $B,090/yr
Implementation cost = $29,440
Simple payback = 3.6yr
Estimated waste reduction = 617,760 gal/yr
Raw material cost savings = $2,200/yr
Implementation cost = $16,900
Simple payback = 7.7yr
Estimated waste reduction = none
Raw material cost savings = $2,800/yr
Implementation cost = $17,940
Simple payback = 6.4 yr
Estimated waste reduction = 262,00 gal/yr
Raw material cost savings = $940fyr
Energy cost savings = $870/yr
Boiler feedwater chemical cost savings
     = $3,SOO/yr  '
Total cost savings = $S,310/yr
Implementation cost = $33,700
Simple payback = 6.3 yr
 United States
 Environmental Protection
     Center for Environmental
     Research Information
     Cincinnati, OH 45268
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