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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. In an effort to assist these manufacturers 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). That document has been superseded by the Facility Pollution Prevention

Guide (EPA/600/R-92/088). The WMAC team at the University

of Tennessee performed an assessment at a plant that fabricates and finishes metal components that are assembled into

several types of locking devices. Raw materials are machined

and then shipped offsite for heat-treating, stored until needed,

or buffed and cleaned. Then, all parts other than those made

of stainless steel are electroplated, electrostatically powder

coated, or lacquer coated. The various component parts are

then assembled into the locking devices. The assessment

team’s report, detailing findings and recommendations, indicated that the vapor degreasers generate a significant amount

of waste and that vapor degreasing could be replaced with an

aqueous cleaning system for intermediate cleaning.

This Research Brief was developed by the principal investigators and EPA’s National Risk Management Research Laboratory, Cincinnati, 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 become an increasingly costly problem for manufacturers and an

additional stress on the environment. One solution to the

problem of waste generation 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 generation of waste but who lack

the in-house expertise to do so. Under agreement with EPA’s

National Risk Management Research Laboratory, the Science

Center has established three WMACs. This assessment was

done by engineering faculty and students at the University of

Tennessee 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 pollution prevention 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 in-house expertise in pollution prevention.

The potential benefits of the pilot project include minimization

of the amount of waste generated by manufacturers, and

reduction of waste treatment and disposal costs for participating plants. In addition, the project provides valuable experience for graduate and undergraduate students who participate

in the program, and a cleaner environment without more regulations and higher costs for manufacturers.

Pollution Prevention Assessment for a Manufacturer

of Locking Devices

ENVIRONMENTAL

RESEARCH BRIEF

Richard J. Jendrucko*, Brian T. Hurst*,

and Gwen P. Looby

E AP

United States

Environmental Protection

Agency

National Risk Management

Research Laboratory

Cincinnati, OH 45268

Research and Development EPA/600/S-95/013 August 1995

* University of Tennessee, Department of Engineering Science and Mechanics ** University City Science Center, Philadelphia, PA
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Methodology of Assessments

The pollution prevention opportunity assessments require several site visits to each client served. In general, the WMACs

follow the procedures outlined in the EPA Waste Minimization

Opportunity Assessment Manual (EPA/625/7-88/003, July 1988).

The 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

This plant fabricates and finishes metal components which are

assembled into several types of locking devices. Approximately one million units are produced annually by this plant

during 5,880 hr/yr of operation.

Manufacturing Process

The operations used by this plant are described below.

Component Parts Manufacturing

The major raw materials used by the plant include zinc die

castings and carbon and stainless steel, brass, and bronze in

bars, coils, and rods. Raw materials are moved by forklift to

the metal fabrication area where cutting, bending and shaping,

drilling, milling, screwing, and tapping operations are performed.

Prior to subsequent finishing operations, residual machining

lubricant is removed from the parts in one of two vapor

degreasers utilizing trichloroethylene. Contaminated trichloroethylene is distilled onsite and reused.

After cleaning, the parts are processed in one of three ways.

Some of the steel parts are shipped offsite for heat treatment

and then returned to the plant for further processing. A portion

of the parts is placed into storage until needed for production at

a later time. The majority of parts which become external

locking device parts are buffed to improve their appearance,

either by hand or in an automatic system. Parts that have

been buffed are cleaned in a third vapor degreaser.

All parts except those made of stainless steel require a surface

coating. Most of the parts require one or more layers of

electroplating. The second major type of coating used is

electrostatic coating, and the third type is lacquer application to

prevent tarnishing.

After the necessary coating process is complete, the component parts are transported to the assembly area where the

different locking devices are assembled and packaged.

Electroplating Operations

Because the electroplating operations generate a significant

amount of waste they are described in more detail in this

section.

Parts that are to be plated that have not been buffed are first

placed into vibratory devices for removal of any surface irregularities. Those parts are then conveyed through a small vapor

degreaser, washed in a series of two wash tanks, and rinsed.

Three different plating lines are used by the plant. A small

quantity of special parts is plated in a small-scale hand-plating

line. Typical plating runs include chrome-or black chrome-,

bronze-, or brass-plating and hot water rinsing between each

plating stage and at conclusion.

Smaller parts that are used on the majority of the locking

devices are placed into barrels for plating in the barrel-plating

line. For corrosion protection, typical plating includes copper

striking and plating, dull and bright nickel plating, and chrome

plating with hot water rinsing between each stage and at a final

rinsing station.

Larger parts are placed onto racks and mechanically carried

through the rack-plating line. These parts are plated with zinc,

copper strike and plating, bronze, brass, nickel, and chrome for

decoration.

After parts have been processed through the appropriate plating line, they are removed from the conveying devices, allowed

to air dry, and carried to the assembly area.

An abbreviated process flow diagram for this plant is shown in

Figure 1.

Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes.

• A filter press and a drying oven are used to reduce the volume

of hazardous wastewater treatment sludge shipped offsite.

• Each vapor degreaser is served by a distillation unit for the

recycle and reuse of spent trichloroethylene.

• Counterflow rinsing is used in the plating operations.

• Flow restrictors have been installed on the water removal

lines of the electroplating rinse tanks to reduce the volume of

wastewater generated.

• A compactor is used to reduce the volume of nonhazardous

solid waste shipped to the municipal landfill.

• Water-based coolant and cutting oil is removed from metal

shavings using a centrifuge and returned to the metal fabrication units.

• Scrap metal shavings are recycled offsite.

• Canvas coverings have been installed over the openings of

the vapor degreaser units to reduce evaporative losses of

solvent.

Pollution Prevention Opportunities

The type of waste currently generated by the plant, the source

of the waste, the waste management method, the quantity of

the waste, and the annual treatment and disposal cost for each

waste stream identified are given in Table 1.

Table 2 shows the opportunities for pollution prevention that

the WMAC team recommended for the plant. The opportunity,

the type of waste, the possible waste reduction and associated

savings, and the implementation cost along with the simple

payback time are given in the table. The quantities of waste
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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 savings of the opportunity, in most cases, results from the reduction in raw material

and costs associated with 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 also should be noted that the

savings given for each opportunity reflect that pollution prevention opportunity alone and do not reflect duplication of savings

that may result when the opportunities are implemented in a

package.

Additional Recommendations

In addition to the opportunities recommended and analyzed by

the WMAC team, two other measures were considered. These

measures were not analyzed completely because of a lack of

sufficient information for analysis or an anticipated lengthy

payback period. Since these approaches to pollution prevention may, however, increase in attractiveness with changing

conditions in the plant, they were brought to the plant’s attention for future consideration.

• Install rinse devices above each plating and wash tank to

spray water onto each part as it is removed from the tank in

order to return plating and wash solutions to their tanks

before drag-out occurs. In order to compensate for the

increased amount of water being added to the tanks, it is

proposed that fan units be used to blow air across the surface

of each tank to promote evaporation of excess water. Dragout boards should be installed on each tank.

• Implement electrostatic application of lacquer coating to

component surfaces to reduce the current level of overspray

and raw material purchases.

This research brief summarizes a part of the work done under

Cooperation 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.
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Figure 1. Abbreviated process flow diagram for locking device fabrication.

Storage

Offsite

heat-treating

Metal

fabrication

Vapor

degreasing

Buffing

Vapor

degreasing

Electroplating

Electroplating

powder coating

Spray laquer

application

Assembly Finished locking

devices stored

until shipped

Metal

stock
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Table 1. Summary of Current Waste Generation

Annual Quantity Annual Waste

Waste Stream Generated Source of Waste Waste Management Method Generated (lb/yr) Management Cost1

Cardboard packaging Raw material shipments Compacted; shipped to municipal landfill 218,400 $30,740

Wooden pallets Raw material shipments Compacted; shipped to municipal landfill 46,800 6,590

Miscellaneous solid waste Raw material shipments, buffing, electrostatic coating Compacted; shipped to municipal landfill 47,200 6,640

Brass shavings Machining Lubricant removed; sold to recycler 390,200 -314,990

 (net revenue received)

Steel shavings Machining Lubricant removed; sold to recycler 1,069,700 -11,210

 (net revenue received)

Mixed metal shavings Machining Lubricant removed; sold to recycler 247,370 -48,020

 (net revenue received)

Spent trichloroethylene Annual draining of vapor degreasers Shipped offsite for disposal as hazardous waste 28,700 41,590

Trichloroethylene still bottoms Onsite distillation units for trichloroethylene reuse Shipped offsite for disposal as hazardous waste 3,000 11,590

Evaporated trichloroethylene Vapor degreasers Evaporates to plant air 143,500 73,540

Cooling water Vapor degreasers Sewered 140,000,000 26,750

Corrosive solids Lacquer removal tanks for defectively coated parts Shipped offsite for disposal as hazardous waste 5,010 17,250

Waste lacquer thinner Lacquer application error Shipped offsite for disposal as hazardous waste 1,960 10,470

Wastewater Electroplating Treated in onsite wastewater treatment plant 140,000,000 19,310

 piped to surface waters under NPDES permit

Wastewater treatment sludge Onsite wastewater treatment plant Shipped offsite for disposal as hazardous waste 51,040 57,900

1Includes waste treatment, disposal, and handling costs, and applicable raw material costs.
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Table 2. Summary of Recommended Pollution Prevention Opportunities

Annual Waste Reduction

Net Annual Implementation Simple

Pollution Prevention Opportunity Waste Reduced Quantity (lb/yr) Per cent Savings Cost Payback (yr)

Discontinue the use of the primary vapor Spent trichloroethylene 8,610 30 $28,680 $56,700 2.0

degreasing unit for intermediate cleaning

during machining operations. Install an Trichloroethylene still bottoms 900 30

aqueous cleaning solution system to remove lubricant residues and then dry the Evaporated trichloroethylene 43,050 30

parts with forced-air blowers. Secondary

degreasing units should be used for the

final removal of surface contaminants

prior to electroplating operations. A nonhazardous water/detergent waste stream

will be generated if this opportunity is implemented.

Re-train the vapor degreaser operators to Evaporated trichloroethylene 71,750 50 32,290 0 0

lower the existing canvas covers over the

entrance and exit openings of each degreaser unit in order to decrease trichloroethylene evaporative losses. Currently, the

canvas coverings are not routinely used.

Institute a recycling program to segregate Cardboard packaging —- —- 15,7851 0 0

cardboard and wood material from other

solid wastes for cardboard recycling and Wooden pallets —- —-

sale of wood for domestic heating. Implementation of this measure will lead to Miscellaneous solid waste —- —-

revenue generation through the sale of

waste material and reduced landfill costs.

No waste reduction will result from this

measure.

Install a cooling tower in order to recycle Cooling water 133,000,000 95 22,1701 59,000 2.7

the cooling water used to reduce evaporative losses from the vapor degreasers.

Currently, water is delivered to the units

continuously and carried directly to the

POTW.

1Total annual savings have been reduced by an annual operating cost required for implementation.
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BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

United States

Environmental Protection Agency

National Risk Management Research Laboratory (G-72)

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/S-95/013