United States
                         Environmental Protection
                                     Risk Reduction
                                     Engineering Laboratory
                                     Cincinnati OH 45268
                         Research and Development
                                     EPA/600/S-92/015 April 1992
           Waste  Minimization Assessment for a Manufacturer of Metal
                        Bands, Clamps, Retainers, and Tooling

                               F. William Kirsch and Gwen P. Looby*
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 hazardous waste but
who lack the expertise to do so. Waste Minimization Assess-
ment Centers (WMACs) were established at selected universi-
ties and procedures were adapted from the EPA Waste Mini-
mization Opportunity Assessment Manual (EPA/625/7-88/003,
July 1988). The WMAC team at Colorado State University
performed an assessment at a plant that  manufactures metal
bands, clamps, retainers, and tooling—approximately 2 million
Ib/yr of product. Metal undergoes cutting, machining, cleaning,
and electroplating as  required. The specific processes are
determined  by  the particular product  being produced. The
team's report, detailing findings and recommendations, indi-
cated the most waste was generated by metal cleaning and
that the greatest cost savings would result from using deion-
ized water instead of tap water to make up and maintain the
reagent baths in the metal cleaning and electroplating lines.

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 the authors.
The amount of hazardous waste generated by industrial plants
has become an increasingly costly problem for manufacturers
and an additional stress on the environment. One solution 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 manufacturers

* University City Science Center, Philadelphia, PA 19104
                         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 manu-
                         facturing 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.

                         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
                          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-

                                                   «S> Printed on Recycled Paper

 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
 This plant manufactures metal clamps, bands, retainers, and
 tools used to install clamps and fittings. The plant's 125 em-
 ployees operate  the plant 4,680 hours  per year to produce
 approximately 2 million Ib of product annually.

 Manufacturing Process
 The raw material for the manufacture of bands is received in
 24-in. wide stainless steel coils. The coils are  cut into several
 narrower coils with carbide cutters in a continuous process and
 are wound onto  spools. Sharp edges are  removed and  the
 coils are beveled. Scrap stainless steel from these operations
 Is sold to a scrap-metal dealer.

 Two types of clamps, a closed clamp, with the band threaded
 through the buckle to form a round slip-on clamp, and an open-
 ended clamp, with the buckle attached to the  end of a band,
 are manufactured.

 Clamp fabrication begins by punching out buckles of stainless
 and carbon steel on a hydraulic punch press. The buckles  are
 combined with strips of stainless steel to form the clamps.  For
 a closed clamp, a buckle is crimped onto one end of the band,
 and the other end is inserted into the buckle to form a cylindri-
 cal clamp. Open-ended clamps  are fabricated by  crimping
 buckles  onto the end of the  flat  band  material.  Following
 inspection, the bands are packaged and stored in the ware-
 house prior to final shipment.

 For customers who prefer to purchase the band material and
 the buckles separately, specialized tools to apply and install
 clamps  and fittings are also fabricated by this plant. Iron blanks
 are forged off-site by  a third party and  machined on-site by
 drilling holes, tapping threads, cutting slots,  and creating vari-
 ous surface finishes. Waste cutting fluid  and hydraulic oil  are
 sent to an incinerator. To remove in-situ stresses created from
 machining, the tools are heated to about 1700°F, quenched in
 oil, washed with a caustic cleaner, and annealed in one of two
 draw furnaces.

 The tools are then placed in electroplating barrels in prepara-
 tion for further processing. The barrels are immersed in  the
 following tanks which make up the metal cleaning line: caustic
 cleaner, electrosoap, tap-water rinse, acidic cleaner, cascade
 rinse (consists of two tanks), and acid stripper.

 The caustic cleaning solution is prepared from a concentrate
 that contains sodium hydroxide  and sodium metasilicate and is
 maintained at 180°F. The 560-gal tank is dumped about every
 6  months; the spent solution, along with other waste liquids
 from the metal-cleaning line, drains into a small sump, is tested
 and balanced for proper pH in a surge tank,  and is discharged
to the sewer system  as  industrial waste water. Usually, very
 little pH adjustment is required because the  spent cleaning
 solution is mixed with spent acidic solutions.

 The  alkaline  electrosoap solution is prepared from a reagent
that contains sodium hydroxide and sodium  silicate. A voltage
 is applied to provide anodic electrocleaning. This  solution is
 maintained at 180°F, and the 281-gal tank is dumped about
 every 6  months.  Spent solution is treated  with other waste
water from the cleaning line.
Sludge, which  contains precipitated  hard-water ions,  surface
contaminants removed from the parts, and heavy  metals from
cleaning buckles and reworked material, accumulates in the
bottoms of the  caustic cleaner and electrosoap tanks.  Periodi-
cally, the sludge is removed from the tanks,  drummed,  and
shipped off-site for hazardous waste disposal.

The tap-water rinse and the cascade  rinse are continuous-flow
rinses. Most of  the liquid waste from the cleaning line consists
of water from the tap-water rinse following the electrosoap bath
and the cascade rinse  following the acidic  cleaner. The two
effluents mix in the sump and tend to neutralize and thus,  little
pH adjustment  is required.            ;

The acidic cleaner solution is prepared by diluting a cleaning
reagent that consists  of sodium fluoride. The 281-gal tank is
drained about every 6 months. Spent cleaner is treated with
other waste from the cleaning line.

The last tank of the metal cleaning  line  is the acid stripping
tank. The  acid  stripping solution which  consists of sulfuric,
hydrochloric, phosphoric acids,  and soaps, is used to  remove
zinc plating from rejected parts. There is no continuous  dis-
charge from this tank; the solution lifetime is at least 2 years.
Spent stripper is shipped to an off-site hazardous waste facility
for disposal.

After the metal cleaning  line, the electroplating barrels are then
sent through the zinc electroplating line which consists of the
following 6 tanks:  acid zinc plating, 2-tank cascade rinse,
brightener, tap-water rinse,  and  hot rinse. The acid zinc plating
solution contains sulfuric acid and ammonium chloride. Hydro-
gen peroxide is added weekly to the plating solution for  mainte-
nance, and the  solution is filtered to remove any solid contami-
nants. To provide optimum plating conditions, the solution  is
cooled to below 80°F.  Spent plating solution is shipped off-site
for hazardous waste disposal.

Rinse water from the zinc plating line  is treated to remove zinc
and reused. Lime is added for pH adjustment prior to treatment
in an electrpcoagulation unit which  consists of two  parallel
tubes containing aluminum anodes. Current  applied to  the
sacrificial anodes precipitates metal hydroxides. Treated water
flows through a filter press to remove  hydroxides and is reused
as rinse water.  Sludge is shipped off-site for hazardous waste
disposal. The barrels containing the plated parts are then sent
through the cascade rinse.

The brightener tank, which follows,  contains a solution pre-
pared from an acidic reagent that consists of nitric acid, chro-
mic nitrate, and ammonium bifluoride. The 281-gal tank is not
dumped during  normal  operations, although the solution  is
periodically drained and  replenished.  Spent  brightener  is
drummed and shipped off-site for hazardous  waste disposal.

Following  an air-agitated, recycled-water  rinse,  is a  heated
rinse. Effluent from the heated rinse is treated with other rinse
waters and sewered.                 !

The plated tools are combined with assorted fittings and parts
in the assembly area. After inspection, the tools are packaged
and stored to await shipment.

Minor liquid waste streams include kerosene and quenching
oil. Kerosene is used as  a cleaning solvent in  the  air-tool
assembly  area. The minor amounts that are used typically
evaporate; no waste kerosene is manifested and shipped off-

site for disposal, so this waste stream was not included in
Table 1. About 700 gallons of petroleum-based quenching oil
are used in the heat treating operations. The oil typically lasts
about 7 years before disposal is required, so this waste was
not evaluated for this assessment.
Existing Waste Management Practices
This plant has taken the following steps to manage and mini-
mize its wastes:
        Excess metal is segregated on-site and sold to a
        scrap-metal dealer for recycling.

    •   Rinse water from the plating line is treated to
        remove metal contaminants and reused.

    •   Air-agitation is used for rinses in the zinc plating

    •   The zinc plating solution is filtered to remove
        solid contaminants.

    •   The use of leaded steel for banding tools has
        been discontinued.

    •   Cascade rinses are used in the metal cleaning
        and zinc plating lines.
Waste Minimization Opportunities
Table 1 shows the sources of the plant's waste streams, the
amounts of waste generated, the management method used,
and the associated costs.

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 indepen-
                    dently  and do  not  reflect duplication of savings that would
                    result when the opportunities are implemented in  a package.

                    Additional Recommendations
                    In addition to the opportunities recommended and analyzed by
                    the WMAC team,  several additional measures were consid-
                    ered. These measures were  not analyzed completely because
                    of insufficient data,  implementation difficulty, or a  projected
                    lengthy payback as indicated below. Since one or more of
                    these approaches to waste reduction may, however, increase
                    in attractiveness with changing conditions in the plant, they
                    were brought to the plant's attention for future consideration.

                        •   Institute a formal cutting-fluid management pro-
                            gram to reduce the volume of spent cutting-fluid
                            wastes that require disposal.

                        •   Replace the kerosene, which is used as  a clean-
                            ing solvent in the assembly area, with a  non-
                            hazardous aqueous cleaner.

                        •   Install  an automated pH-adjuster to regulate the
                            pH of the effluent from the metal cleaning line in
                            order to prevent potential compliance problems.
                    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. Environmen-
                    tal Protection Agency. The EPA Project Officer was Emma Lou
Table 1. Summary of Current Waste Generation
 Waste Stream
    Disposal Method
 Waste Disposal
Annual Quantity
Annual Cost
Liquid waste
         Metal Cleaning
               Caustic cleaner
               Acidic cleaner
               Cascade rinse
               Acid stripper
               Zinc Plating

               Waste oil/cutting fluid

Solid waste
         Metal cleaning
               Caustic cleaner/electro-
               soap sludge

         Zinc plating
               Water recycler sludge
pH adjusted and sewered
pH adjusted and sewered
pH adjusted and sewered
pH adjusted and sewered
pH adjusted and sewered
Off-site disposal

Off-site disposal
Off-site disposal
Off-site incineration
Off-site disposal
Off-site disposal

  $  0

                                                                                   •US. Government Printing Office: 1992 — 648-060/60077

Tnbto2.  Summary of Recommended Waste Minimization Opportunitas
Present Practice
Proposed Action
Waste Reduction and Associated Savings
Tha tap-water rinse In the
metal cleaning process line
uses tap-water as make-up
Higher-grade scrap metals are
combined with hwergra.de
scrap before being sent to the
metal recyder. The recycling
credit fs reduced because of
this practice.

Tap-water is uesed to make and
maintain the reagent baths In
the metal cleaning and zinc
electroplating process lines.
The drainage time of parts
over tftfl cawstfc cleaner and
eloctfosoap tanks Is about 5
Rinse water rates set by
opertors In the tap-water and
cascade rinses of the metal
cleaning line are often higher than
required by the process.
Redirect the rinse water overflow from the
cascade rinse in the metal cleaning process
line to replace the tap-water make-up. Waste
reduction and cost savings will result from
the reduced amount of water that must be
purchased and sewered.

Improve the segregation of stainless steel
scrap, iron turnings, and ohter scrap metals.
No waste reduction will result from this
measure, but the amount of cash received from
the recyder will increase.
Use deionized water to make and maintain the
caustic cleaner, electrosoap, acid cleaner,
zinc electroplating, and brightener solutions.
Less sludge will thereby be generated in the
caustic cleaner tank.
Increase the drainage time over the caustic
cleaner and electrosoap tanks to ten seconds.
The volume of solution which drains back into
the tanks will increase and therefore the
bath lifetimes will increase..

Reduce water usage by installing flow
reducers and flow meters on the rinse tanks
In the metal cleaning line.
Waste reduction = 650,000 gal/yr
Cost savings = $1,110/yr
Operating cost of required pump = $20/yr
Net cost savings = $1,090/yr
Implementation cost = $470
Simple payback - 0.4 yr

Cost savings = $950/yr  :
Implementation cost = $0
Simple payback is immediate.
Waste reduction = 150 gal/yr
Cost savings = $1,820/yr.
Operating cost of the required Ion exchange
     unit = $450/yr
Net cost savings = $1,370/yr
Implementation cost => $0
     (The ion exhange unit will be rented and
     that cost is included,In the above operating
Simple payback is immediate.

Waste reduction = 250 gal/yr
Cost savings = $340/yr
Implementation cost = $0
Simple payback is immediate.
Waste reduction = 124,800 gal/yr
Cost savings = $220/yr
Implementation cost = $130
Simple payback - 0.6yr
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