United Stales
                                Environmental Protection
                                  Risk Reduction
                                  Engineering Laboratory
                                  Cincinnati, OH 45268
                                Research and Development
                                  EPA/600/M-91/046  Oct. 1991
              Waste Minimization Assessment for a Manufacturer of
                             Speed Reduction Equipment

                            F. William Kirsch and J. Clifford Maginn*

 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
 lack the expertise to do so. Waste Minimization Assessment
 Centers (WMACs) were established at selected universities
 and procedures were adapted from the EPA Waste Minimiza-
 tion Opportunity Assessment Manual (EPA/625/7-88/003 July
 1988). The WMAC team at Colorado State University per-
 formed an assessment at a plant manufacturing speed reduc-
 tion equipment - approximately 110,000 speed reduction units/
 yr. Plant operations include machining and assembling parts
 for worm gear shafts and other shafts, worm gear bodies hubs
 and housings, bearings and seals. Keyed and threaded shafts
 are case-hardened, ground with athread grinder, and deburred.
 Component parts are washed with an aqueous cleaner before
 assembly, and finished assemblies are spray painted with
 solvent-based paints and lacquer thinner. Spent cutting fluid
 and sludge, including turnings, and spent wash water are
 shipped offsite for disposal. Spent hydraulic oil and nonaqueous
 cutting fluid are shipped to a recycler. Waste paint and spent
 lacquer thinner are shipped offsite for incineration. The team's
 report, detailing findings and recommendations, indicated that
 most waste consists of spent aqueous cutting fluid, and that the
•University City Science Center. Philadelphia, PA 19104.
               greatest savings could be obtained by ultrafiltration and recycle
               of spent wash water.

               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 aseparate 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
               who want to minimize their formation of hazardous waste but
               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 (FortCollins) WMAC. The assessmentteams 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

                                    {g/y Printed on Recycled Paper

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 lackinhouse 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
procedures outlined in the EPA Waste Minimization Opportu-
nity Assessment Manual (EPA/625/7-88/003, July 1988). The
WM AC 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.
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 produces  speed-reduction equipment. The plant
operates 7,480 hr/yr to produce approximately 110,000 speed
reduction units.

Manufacturing Process
The plant machines and assembles parts for worm gear shafts
and other shafts, worm gear bodies, hubs and housings,
bearings and seals. (The term "worm gear" refers to a compo-
nent part of speed reduction units.) Except for bearings, motors
and cast housings, all speed reduction unit parts are made in
the plant. Raw materials include steel and bronze bar stock,
aluminum and iron castings, cutting fluids, paint and lacquer

The following operations are involved in making the speed
 reduction units:

   • Worm gear shafts are machined from bar stock. Key slots
     are cut, and a thread mill cuts worm gear threads in the
     shafts. After case-hardening in  a gas-fired carburizing
     furnace, the shafts are ground with a thread grinder and
     deburred in a tumbler with ceramic chips and an aqueous
     slurry of aluminum oxide.
   • Worm gear bodies, made of a bronze alloy, are machined
     on a numerically controlled machine and pressed on the
   • Spent cutting fluid and sludge containing metal turnings
     are shipped for offs'rte disposal.  Spent hydraulic oil and
     nonaqueous cutting fluid  are shipped to a waste oil recy-
   • Most component parts are washed with a water soluble
     cleaner before  assembly.  Spent wash water and mop
     water from cleanup around machinery are shipped offs'rte
     for disposal.
   • Many of the finished assemblies are spray painted using
     solvent-based paints and lacquerthinner. Waste paint and
    spent lacquerthinner are shipped offs'rte for incineration in
    a cement plant. Spent paint-booth air-filter elements are
    discarded with conventional trash.

Existing Waste Management Practices
  • Metal scraps and chips are segregated and sold to a scrap
    metal dealer for recycling.
  • For drilling and tapping operations the plant uses a lubri-
    cant with reduced emission of volatile organic compounds
    (VOCs). Nonhazardous waste oil is processed offs'rte by a
    recycler and blended into industrial boiler fuel. Solvent-
    based cleaners have been replaced by a nonhazardous
    aqueous cleaning solution.
  • Spent cutting fluid is occasionally filtered  and re-used.
  • Dry booths are used for painting, eliminating the aqueous
    paint-laden wastes  associated with wet paint booths.

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 manage-
ment costs are given in  Table 1.

Table 2 shows the opportunities for waste minimization that the
WMACteam recommended forthe 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 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, four additional measures were considered.
These measures were not completely analyzed  because of
 insufficient data  or minimal savings as indicated below. They
were brought to the plant's  attention for future reference,
 however, since  these  approaches to waste reduction may
 increase in attractiveness with changing plant conditions.

   • Treat spent wash water and mop water containing sulf uric
     acid to separate organic and aqueous phases. The organ-
     ics would be shipped for offs'rte disposal, but the water
     phase could be sewered to a local industrial wastewater
     treatment facility.  Because the plant does not have  an
      industrial sewer connection.at this time, this measure was
      not recommended. Ultrafiltration was recommended  in-
      stead, because it provides an aqueous phase suitable for
      discharge to the POTW sewer or re-use as mop water.
   •  Install a tramp-oil separator and two outside atmospheric
      evaporators to reduce the quantity of wastewater shipped

      offsite for disposal. Because expected savings are small,
      with a long payback period, this measure was not recom-
      Replace two water-soluble cutting fluids now in use with a
      single standardized cutting fluid. Because the resulting
      waste reduction and  savings resist quantification, this
      measure was not recommended. However, if the recom-
      mendation to recycle the cutting fluid is implemented, use
      of a single cutting fluid will reduce substantially the cost of
      equipment and operating costs.
 Table 1. Summary of Current Waste Generation
                                            •  Install tramp-oil separators on the washers to allow recycle
                                               of the alkaline wash water. The extended life of the wash
                                               water would result in waste reduction, but the expected
                                               cost savings would be small in comparison to operating

                                          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
Waste Generated
Spent cutting fluid
Cutting fluid sludge
Cutting fluid and rainwater
Spend hydraulic oil and
nonaqueous cutting oil
Source of Waste
Decanted from metal chips produced in machining operations.
Shipped for offsite disposal.
Metal chips sludge produced in machining operations.
Shipped for offsite disposal.
Runoff to pit drainage from metal chips collection bins.
Drained from machinery when no longer effective. Shipped
to a waste oil recyder.
Annual Quantity
61. 380 gal
650 gal
12,480 gal
3,000 gal
Annual Waste
Management Cost
 Waste paint (sludge) and
       Sludge formed as the paint becomes too thick and the
       thinner no longer useful for thinning or cleaning. Shipped for
       incineration in a cement plant.
                                     2,150 gal
 Spent air filter elements      Paint booth ventilation air filtration. Conventional trash disposal.
Spent wash water
Spent mop water
Spent aqueous cleaning solution from cleaning finished metal
parts before assembly. Shipped for offsite disposal.
Soapy mop water from cleanup around plant machinery. Shipped
for offsite disposal.
1,200 gal
9,420 gal
 Table 2.  Summary of Recommended Waste Minimization Opportunities
Waste Generated
 Minimization Opportunity
Annual Waste Reduction         Net        Implementation   Payback
 Quantity     Percent    Annual Savings        Cost          Years
Paint waste from
cleaning spray guns
Spent aqueous
cutting fluids
 Use waste-based paints instead of    2,150 gal
 solvent-based paints to eliminate
 solvent and thinner and produce only
 conventional,  nonhazardous waste.

 Filter and recycle the aqueous     31,340 gal
 cutting fluids.
Spent mop water from  Install an ultrafiltration system to     9,420 gal
cleanup around        process spent wash water for use as
machinery            mop water. Excess treated water can
                     be discharged to the POTW. Only the
                     separated oil layer need be shipped
                     for disposal.








Spent cutting fluid
from chip collection
Use a portable sump cleaner to
remove accumulated cutting fluid
from chip collection bins for filtration
and recycle (as proposed above for
recycle of spent cutting fluid).
 12,480 gal
'Includes savings on raw materials.
                                                                       •ArU.S. GOVERNMENT PRINTING OFFICE: 1991 - 548428/40074

United States
Environmental Protection
Center for Environmental Research
Cincinnati OH 45268
Official Business
Penalty for Private Use $300