United States
                         Environmental Protection
                         Agency
                         Research and Development
           Risk Reduction
           Engineering Laboratory
           Cincinnati, OH 45268
           EPA/600/S-92/030   Sept. 1992
                         ENVIRONMENTAL
                         RESEARCH   BRIEF
                          Waste Minimization Assessment for a
                     Manufacturer of Finished Metal Components

                             Harry W. Edwards and Michael F. Kostrzewa*
                             F. William Kirsch and J. Clifford Maginn"
Abstract
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 Waste Minimization Oppor-
tunity Assessment Manual (EPA/625/7-88/003, July 1988). The
WMAC team at Colorado State University performed an as-
sessment at a plant manufacturing finished metal components
— approximately 260,000 sq ft/yr. Customer-specified coatings
and surface treatments are applied to prefabricated  aluminum
and stainless steel parts. Aluminum parts may be finished by
hard-coat or soft-coat anodizing, and chromate conversioq
coating. Stainless steel parts are finished by surface passivation.
Parts are also processed for surface inspection using a fluo-
rescent dye and ultraviolet light. The team's report, detailing
findings and recommendations, indicated that most waste was
generated  in the aluminum anodizing process, and that the
greatest savings could be obtained by using hot  deionized
water instead of nickel acetate solution to seal pores  in the
aluminum oxide coating applied by anodizing.

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


Introduction
The amount of waste generated by industrial plants has be-
come an increasingly costly problem for manufacturers and an
' Colorado State University, Department of Mechanical Engineering
" University City Science Center, Philadelphia, PA
additional stress on  the environment.  One solution  to the
problem 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 hazardous waste but
who lack the inhouse expertise to do so. Under agreement
with EPA's Risk Reduction Engineering Laboratory, the Science
Center has established three WMACs. This assessment 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 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 $75 million, employ no more than
500 persons, and lack inhouse 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 pro-
cedures outlined in the EPA Waste Minimization Opportunity
Assessment Manual (EPA/625/7-88/003,  July  1988). The
                                                                               Printed on Recycled Paper

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  WMAC staff locate  the  sources of waste  in the plant and
  identify 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
  technological and economic information is developed  Finally
  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 is  a metal-finishing job shop that applies coatings
  and surface treatments to prefabricated metal parts. The plant
  operates 2,448 hr/yr to produce approximately 280,000 sq ft of
  finished metal parts.


  Manufacturing Process
  This plant does hard-coat and soft-coat anodizing, chromate
  conversion  coating, and surface inspection of aluminum parts.
  Processing  of stainless steel parts involves surface passivation
  surface inspection, or both. The raw  materials used include
  aluminum cleaner, NaOH aluminum etch, nitric/hydrofluoric (HF)
  acid deoxidizer, sulfuric acid, dyes, nickel  acetate,  sodium
  dichromate,  chromate conversion coatings,  nitric acid,  hy-
  drofluoric acid, oil-base penetrant, developer, water washable
  penetrant, and hydrophilic emulsifier.

  The following steps are  carried out  in the surface finishinq
  operations:

   • The aluminum anodizing  line involves alkaline  cleaning
     and etching, acidic deoxidizing to remove smut left after
     etching, anodizing in an  electrolytic solution of  sulfuric
     acid, dyeing, and  sealing  the  aluminum oxide layer with
     aqueous nickel acetate.
   • Chromate conversion  coating of  aluminum involves alka-
     line cleaning and etching, acidic deoxidizing, clear or gold-
     colored  chromate conversion coating, and rinsing in deion-
     ized water.
   •  For stainless steel passivation, parts are degreased, etched,
     and immersed in a passivating acid solution.
   •  For surface inspection, parts are first degreased and etched
     A fluorescent dye is then applied  and the surface is illumi-
     nated with ultraviolet light to reveal surface flaws.

 An abbreviated process flow diagram is shown in Figure 1.


 Existing Waste Management Practices
  •  Two-stage and three-stage counterftow rinses in the anod-
     izing and  chromate conversion lines reduce  water  con-
     sumption and waste generation.
  •  Process  solutions  are  made up with deionized water to
     reduce sludge formation.
  •  Drain boards are used between solution tanks to reduce
     dragout.
  •  Spent  etching  solution  is  used for  adjusting  the  Ph of
     spent rinse water.


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 man-
agement costs are given in Table 1.
  Table 2 shows the opportunities for waste minimization that the
  WMAC team recommended for the  plant. The type of waste
  the minimization opportunity, the possible waste reduction and
  associated savings, and the implementation cost along with the
  payback time are given in the table. The quantities of hazardous
  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, in most cases, the economic savings of
  the minimization opportunities  result from the need for less raw
  material and from reduced present and future costs associated
  with hazardous waste 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 opportunities are implemented in  a package.

  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. Environmental
  Protection Agency. The EPA Project Officer was Emma  Lou
  George.
Aluminum Parts
from Customers'
    Surface Inspection
    - Cleaning
    - Etching
    • Inspection
                   Anodizing

                   - Cleaning
                   - Etching
                   - Anodizing
                   - Dyeing
                   - Sealing
             Chromate
             Conversion Coating

             - Cleaning
             - Chromate Conversion
Stainless Steel
Parts from 	
Customers
Surface Inspection
- Cleaning
- Etching
- Inspection
                 Passivation
                 - Cleaning
                 - Passivation
Finished
Parts
Shipped
to Customers
                                                             Figure 1.  Abbreviated process flow diagram.

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Table 1. Summary of Current Waste Generation
Waste Generated
 Source of Waste
Spent rinse water
Spent anodizing solutions
Spent chromate conversion
coating solutions
Spent passivation solutions




Spent acidic etchant solution



Spent penetrants



Batch treatment sludge
Annual Quantity
Generated (gal)
  Annual Waste
Management Cost
Rinse waters from anodizing, chromate conversion           1,547,734
coating, and surface inspection are Ph adjusted
and discarded as industrial wastewater.

Aluminum cleaner, alkaline etch bath, acidic                    5,000
deoxidizer solution, anodizing reagent solution,
and dyeing and nickel acetate seal solutions are
batch treated (Ph adjusted) and discarded with
rinse water as industrial wastewater.

Hexa valent chromate solutions are reduced with                  641
sodium metabisulfite; then, with aluminum cleaner,
alkaline etch bath, and acidic deoxidizer solution,
are batch treated (Ph adjusted) and discarded
with rinse water as industrial wastewater.

Hexavalent chromium solutions are reduced with                 125
sodium metabisulfite and, with nitric acid solutions,
are batch treated (Ph adjusted) and discarded with
rinse water as industrial wastewater.

Spent acidic etchant from surface inspection is                    40
batch treated to adjust Ph and precipitate  dissolved
metals then discarded as industrial wastewater.

Spent dyes, developer,  and emulsifier from surface                 20
inspection are shipped as hazardous  waste for use
as cement kiln fuel.

Sludge (metal hydroxides and trivalent chromium                 150
compounds) from treatment of spent process
solutions and rinse waters is disposed of as
hazardous waste.
                        $19,963
                          8,589
                            759
                            306
                            123
                            985
                                                                                                                 5,191
                                                                              •fru.g. GOVERNMENT PUNTING OFFICE: MM - 55»4C7/M)Ma

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 Table 2.  Summary of Recommended Waste Minimization Opportunities
 Waste Generated
Minimization Opportunity
                                                       Annual Waste Reduction
                                                                Net
                                                     Quantity (gal)
                                          Implementation
              Percent    Annual Savings        Costs
                                            Payback
                                              Years
Spent nickel acetate
seal solution

Nickel hydroxide
sludge from treatment
of spent nickel acetate
solution
Spent anodizing
solutions
Spent reagent solutions
from chromate
conversion coating
Anodizing and chromate
conversion coating
water rinses
Alkaline etch
water rinses
Anodizing and chromate
conversion coating
water rinses
 Use hot deionized water instead
 of nickel acetate as a seal after
 anodizing.
 Use hot deionized water instead
 of nickel acetate as a seal after
 anodizing.

 Neutralize the spent solutions with
 50% aqueous caustic instead of
 sodium hydroxide pellets. Use
 automated metering equipment to
 reduce raw material and labor costs.
 Allow increased drainage time above
 the chromate conversion coating
 line reagent baths. Increased solution
 life will result in waste reduction and
 cost savings.
 Eliminate the soft-coat anodizing
 rinse (use the hard-coat rinses for
 both treatments),  and install timer
 switches to shut off all flowing rinses
 when not in use.
 Use spent acidic deoxidizer rinse
 water instead of tap water for the
 anodizing and chromate conversion
 coating alkaline etch rinses.
 Install flow reducers and flow
 meters on flowing water rinses in
 the anodizing and chromate
 conversion coating lines to avoid
 excessive use of rinse water.
  2,275
    104
100


100
   1,292
651,346
259,820
144,015
 20
 42
 17
 10
$3,094


  1,109



  2,933




  2,498




  2,351




   756



   419
$ 1,020


     0



  1,140
                              2,081
                                                260
                                               1,210
0.3


  0



0.4
                                                                0.9
                                                               0.3
                                               2.9
  United States
  Environmental Protection Agency
  Center for Environmental Research Information
  Cincinnati, OH 45268

  Official Business
  Penalty for Private Use
  $300
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                                                                              PERMIT No. G-35
  EPA/600/S-92/030

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