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                              POLLUTION PREVENTION

             AT AN AGING MIDWESTERN MANUFACTURING FACILITY
       This  report describes the results of an  Industrial  Pollution Prevention Project (IP3)
 demonstration project in Nebraska.  The goal of the project was to demonstrate the adoption of
 pollution prevention (P2) practices by a rural and aging manufacturing facility.

 INTRODUCTION

       The manufacturing facility is located in a predominantly agricultural area. The plant site is
 a 100 acre area on which several buildings are located -- the largest of which is the manufacturing
 facility (805,000 square feet).  The facility produces fabricated metal products for farm and industrial
 uses including structural steel members and plates, farm gates, fencing, and livestock watering tanks,
 in addition to a wide variety of structural bolts, fasteners, etc.   Because of the nature of its
 manufacturing, the  facility is licensed as a hazardous waste generator and is permitted under the
 RCRA and NPDES systems.

       In its various  manufacturing processes,  the facility performs many operations including
 electroplating, conversion coating, cleaning, machining, grinding, impact deformation, shearing,
 welding, sand blasting, hot-dip coating, painting, assembly and testing.  Many of these processes
 result  in the production of a variety of pollutants that have to be disposed of in some fashion
 depending on their nature.  For example, the electroplating line results in the production of acids and
 rinse water containing zinc and chromium, and the hot-dip galvanizing process results in the
 production of acids and rinse water containing  zinc, lead, and iron, which must be treated as a
 hazardous substance containing heavy metals. The painting processes result in the production of
 used industrial cleaners, acids, solvents, and chemicals used in the cleaning and degreasing of metal
 components.

       All process wastewaters produced at this facility are treated in accordance with stipulations
 of the discharge permit. The wastewater is treated by lime and polymer addition and pH adjustment
 before discharge.  In the past, waste disposal at this facility has resulted in potential problems to both
 surface and ground water resources in the area. The waste disposal systems at the facility  constitute
 a major expense. The management at the facility  recognized that the economic viability of the
 facility depended on reducing pollution control expenses and lowering or eliminating the  burden of
 regulation the company must endure.

 P2 OPPORTUNITY ASSESSMENT

       A work plan for the  P2 assessment program was developed identifying  several tasks,
including:

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     1. Development of  a detailed assessment  and  evaluation  of  current  practices and
        characterization of all wastes produced by the facility.

     2. Identification and delineation of all possible P2 opportunities.

     3. Economic and technical evaluation of all waste prevention and minimization alternatives
        including short-term as well as long-term impacts of these alternatives.

     4. Development of recommendations to be made to the management of the manufacturing
        facility for P2 implementation that would be based on economic priority in terms of greatest
        benefit and shortest pay-back periods.

     5. Providing technical assistance, where appropriate, during the process of implementation
        of the recommended alternatives.

     6. Review of the results and impacts after implementation of the recommendations.

       In  developing the work  plan, a multi-media  approach was  emphasized in  developing
pollution prevention and  minimization strategies affecting all operations and processes.
The waste stream evaluation process conducted at the facility followed procedures outlined by the
U.S. Environmental Protection Agency (see References  section at the end of this report: U.S. EPA,
1990; 1992; 1993).

       In  conducting  the P2 opportunity assessment, emphasis became focused on finding those
areas where the impact on reducing the total pollutant  load produced  by this facility could be the
greatest. Those areas were the electroplating, hot-dip galvanizing and  the painting lines as well as
the tube-mill production area.  Because these areas produced the bulk of the wastes with the greatest
toxicity and hazard, it was judged that improvements in  these areas  would produce the greatest
impacts.

The Electroplating Systems

       The manufacturing facility operates both an automated line and  a manual electroplating line.
These lines  are used to deposit a thin zinc film onto small items such  as bolts, fasteners and nuts,
which  are then used  in  the construction of larger  plant products such as farm buildings. The
automatic  electroplating line is a barrel system which plates about 65 kgs (145 Ibs) of work per load.
The barrels are moved by a conveyor chain.

       The automated electroplating line processes an  average of 65 kgs (145 Ibs) of work pieces
per barrel. There are 36 stations on the line, with an approximate cycle time of 3.5 minutes at each
station (about two  hours per barrel).  The work is first cleaned  in  a soak  cleaner and  an
electrocleaning solution. It is then rinsed, pickled in  a hydrochloric  acid bath, and rinsed again
before going into a chloride-zinc electroplating bath. After residing  in the plating bath for about an
hour and ten minutes (20 stations), the work is rinsed. A light yellow chromate finish is added. A

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short rinse (20 seconds) follows the chromating process after which the work is dried at 65 C
(150F). The electroplating solution is circulated through a filter to remove impurities. Particles
removed by the filter are rinsed into the treatment system. The total rinse water use in the automatic
electroplating line at this facility was estimated at 166 liters per minute (20 gpm) during 8 hours of
operation daily.

       The manual process is more operator intensive, which requires hand moving of barrels from
station to station. The barrels are bigger, but the average load of work per barrel is also 65 kgs (145
Ibs). This line is used  more often than the automated line, especially when small quantities need to
be plated. The work is cleaned in a soak cleaning bath (no electrocleaning) for about  15 minutes.
It is then rinsed, pickled in hydrochloric acid, and rinsed again before being placed in the chloride-
zinc electroplating tank (stainless steel pieces are dipped in nitric acid, instead of hydrochloric acid).
The work pieces are plated for an average of 1 to 1.5 hours before being removed from the tank. A
short rinse precedes the chromate coating; which can  be clear or yellow, depending on  customer
preference. After a final short rinse, the pieces are placed on a table to air dry. A  more detailed
analysis of these electroplating lines is given by Parr (1994).

       Pollution Prevention Opportunities in the Electroplating Systems

       House Keeping Practices. To obtain better product quality and assure  that the lower flow
rates will not compromise rinsing efficiency, it was recommended that housekeeping practices be
changed.  There needed to be a thorough cleaning of the electroplating area  including all tanks
(inside and out), floor, and all equipment related to the electroplating process. A system needed to
be established for recording when maintenance is done,  tanks are emptied, chemicals are added, and
testing on tank parameters is performed (e.g. pH, temperature, chemical concentration).

       Rinse Water Use.  The suggested process changes were designed to reduce  waste of both
rinse water and electroplating chemicals. To achieve  these reductions, improved cleanliness and
more careful chemistry control were required. It was recommended that the rinse rates be reduced
to decrease the amount of wastewater  being discharged to the treatment  plant.  For both the
automated and manual electroplating lines, reactive rinsing was recommended in order to decrease
water use from the rinses following the acid dip (pickling) and alkali cleaning processes (Tsai and
Nixon, 1989; Hunt, 1988). Water from the rinse after pickling would no longer go down the drain,
but would instead flow to the rinse tanks following alkali cleaning.  Rinse water flow calculations
showed that for these  two  processes, the required flow on each line could be as low as 8 liters per
minute (2 gpm) (Durney, 1984).

       At this plant, it was found that the effluent from the rinsing step after the acid dip could be
directed to the rinse tanks after the cleaning process. This change would save a total of about 76 m3
(20,000 gal.) of water per day resulting in a cost savings of about $150 per day  in waste treatment,
sludge disposal, and water costs.  Counter-current tanks  similar to those on the automated line (after
the cleaning and acid dip processes) would be needed on the manual line to incorporate this change.
The cost of these counter-current tanks was estimated at $1,000.

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       It was  recommended that the rinse processes after the electroplating tanks on both the
automatic and manual lines be changed to counter-current with a rinse flow rate of 20 liters per
minute (5.3 gpm) each.  About 24 m3 (6,400 gal.) of water per day can be saved, resulting in a cost
reduction of $50 per day. The cost associated with these changes was estimated at $1,000 for the
counter-current tank system.

       Electroplating Chemistry.  The testing of chemical and operating parameters in the tanks
needed to be done on a daily basis for several variables. Electroplating tank variables included pH
and temperature in addition to the concentrations of cleaners, acid dips, zinc metal, boric acid, total
chlorides, and the wetting agent.  Chromating tank variables included pH, temperature, and chromate
concentration.

       Other Changes.  Other recommended changes that were needed to improve  the process
included increasing the temperature of the cleaning tanks on the automatic line from 71 C to 93 C
(160F to 200F). It was noted that a certain amount of grease originating at the machining steps
of bolt production was accumulating in the automatic electroplating line's cleaning tanks.  Grease
skimming from the top of the cleaning tanks needed to be improved to remove more of the grease
and  oil before it carries over  into the downstream  processes.    The filtering system  on the
electroplating tanks needed to be repaired, as it was inoperative. Once the filtering system is repaired
(on both lines), it should be possible to  determine if these  systems are adequate to maintain
contaminants at proper low levels.  In fact, it was recommended that a  new filtering system be
installed.

       It was noted that anode bags should be used to keep contaminants and dirt from the zinc balls
out of the electroplating solution. Also, a drain board needed to be installed over the drip tank after
the chromate rinse (on the auto line) to direct all dragout back into the rinse tank.

       By using a trivalent chrome conversion coating process instead of the hexavalent chrome
process that was being used, the facility should reduce the toxicity of the waste produced. Lower
treatment costs would  be realized since hexavalent chrome must  be chemically reduced to its
trivalent form, which is less expensive to  treat, before  sending it to waste treatment plant.  The
potential disadvantages of these changes would be: a slight reduction in corrosion protection, the
need for closer monitoring and testing of the process,  and  that trivalent chrome coats are only
available in a bright blue color instead of the customary light yellow.

       To recapture some of the chemical dragout from the electroplating and chromating, it was
recommended that still rinse tanks be used after these processes. It is estimated that about 50% of
the chemical  lost to dragout can  be  recaptured by this method (Hunt, 1988).  It  was  also
recommended that air agitation be used in the tanks to increase rinsing efficiency.

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       The electroplating process should be supplied with as clean a water as possible. It was noted
 that the  facility had a reverse osmosis (RO) purification unit which was not in  use, so it was
 recommended that the RO unit be used to supply water to the electroplating, chromating, and still
 rinse tanks. This change would remove potential contaminants in tap water including total dissolved
 solids (TDS) and hardness, thereby increasing process efficiency.

       The barrel withdrawal rates were measured at 5.2 m/min (17 ft/min) in the automated line
 and 8.2 m/min (27 ft/min) in the manual line. According to Foecke (1993), the maximum rate of
 withdrawal should be about 2.4 m/min (8 ft/min). This change would help decrease the amount of
 dragout from each tank resulting in decreased chemical usage.

       It was also recommended that the hang time of the barrels over the tanks be increased by
 pausing longer before moving to next station.  The barrel hang time on the auto line was 23 seconds.
 There was still significant dripping from the barrels after this time period. The hang time over tanks
 on the manual line varied according to operator discretion.  For the most part, hang time was
 observed to be minimal, and dragout was consequently significant.

       Results of Implemented Changes in The Electroplating Systems

       Recommended changes to the automatic electroplating line were presented to the facility. To
 date, four recommendations have been implemented, the results of which are summarized in this
 section.

       The first recommendation to be implemented was to clean the outside and inside of all the
 tanks on the plating line and  remove bottom sludge that had developed. In particular, the bath
 contents of the electroplating tank were pumped into a temporary holding tank and the bottom sludge
 was shoveled into eight 55-gallon drums for disposal (this sludge is not listed as hazardous under
 RCRA regulations). The liquid portion of the plating bath was then pumped back into the plating
 tank and additional chemicals  and water were added to restore them to normal levels.

       Another recommendation that was implemented was regular testing of the cleaning, acid dip,
 electroplating, and chromating processes to maintain chemical  concentrations at their optimum
 levels.

       The third implemented  recommendation  was the  hiring of an employee with suitable
 chemistry background to perform operational control testing (among other duties including the
 galvanizing system chemistry, as discussed below) and report results back to the plating operator so
 that any required chemical additions can be made. The results of this testing are being documented,
 and chemical additions are now being made on a regular basis.

       The fourth implemented recommendation was the reducing of all rinse flows.  Flow control
devices have been installed on  the rinses after the alkaline cleaning and acid dip processes to
maintain  flow rates at the recommended levels. The two systems have not been connected together
as was recommended. The flow rate for the two rinses after electroplating also have been reduced,

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although neither a countercurrent system nor flow control devices have been installed. The new rates
have not been measured, and it has also not been determined if they are being maintained at a
consistent level.  According to the plating operator, the valves controlling flow are not turned on as
far as in the past.  The flows still appear to be above recommended levels (as judged by visual
observation), but until flow control valves  are installed or some other way of producing a consistent
flow is devised, the current method will be continued.

       The  implemented changes also have resulted in significant product quality increases as
evidenced by the results of the 5% neutral salt spray testing (as per ASTM B-l 17) done on  bolts
plated on the automated line before and after the changes were initiated.  These results are presented
in Table 1 below, and show a 1,000% increase in white rust protection and a 550% increase in red
rust protection.
       Table 1.  Results of 5% neutral salt spray tests
Parameter
Hours to White Rust
Hours to Red Rust
Pre-Change
Results
16
48
Post-Change
Results
168
264
Typical
Values
96 - 250
200 - 350
       In conclusion, the facility has been very encouraged by these positive results. Also,
from a waste prevention and minimization  perspective, the  implemented changes have  been
effective. The reduction in rinse flows will no doubt lead to less wastewater needing to be treated
at the waste treatment plant. The cleaning of tanks, removal of sludge, and use of oil absorbent pads
on the cleaning baths should help reduce the drag-out of dirt,  grease, and other contaminants to
downstream processes. This will help to increase bath life which will result in fewer bath dumps and
reduced chemical use.  The costs associated with these implemented changes have been modest.

The Galvanizing System

       The galvanizing process at the facility is a five-step procedure consisting of pickling, rinsing,
prefluxing, galvanizing, and final rinsing.  The  pickling step  prepares work for galvanizing by
removing oxides from the steel surface using a 10% sulfuric acid solution at a temperature of 70 C
(158F). The work pieces are dipped in the pickling acid for varying lengths of time, and then taken
away to be rinsed.

       After pickling, work pieces are rinsed to remove the acid.  The preferred rinsing method is
to dip work pieces in the rinse tank, which is filled with unheated municipal water.  The rinse water
is agitated by moving the work pieces back and forth in the rinse tank.

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       After the first rinsing, work pieces are placed in the preflux tank, which is a crucial step in
the "dry kettle" galvanizing process. The work is coated with flux chemicals (ZnCl2 and NH3C1)
prior to entering the zinc kettle.  The preflux tank is kept at 70C. Normally, the preflux solution
should be allowed to dry thoroughly before proceeding with galvanizing.

       Galvanizing is accomplished by immersing steel in a tank filled with molten zinc for 2 to 3
minutes.  Livestock fencing, the majority of the steel  galvanized at this plant, uses the wet kettle
galvanizing method. This means that a flux  layer is floated on top of the galvanizing kettle. A flux
layer covers the kettle, and work pieces pass through it as they enter and leave the kettle.  For
galvanizing other materials such as building  components, the kettle flux layer is skimmed to the side
and not used.

       The work pieces are cooled by rinsing them in a second  rinse booth located next to the
galvanizing kettle.  This final rinse is needed to cool the work to below 200C (390F), which stops
the possible growth of a brittle zinc-steel alloy layer. Cooling also makes it easier for operators to
handle the work pieces.  A detailed analysis of the galvanizing system at this facility is given by
Montag(1993).

       Pollution Prevention Opportunities in the Galvanizing Process

       Pollution prevention efforts in the  galvanizing area were concentrated  on reducing the
volume and metal content of rinse water since this is the principal medium through which metal is
lost. Volume reductions can be accomplished by installing additional galvanizing equipment. Metal
content reductions are possible by  either discontinuing use of the kettle flux, or switching to a
different kettle flux.

       Rinse Water Use. The galvanizing system at this plant initially used about 265 m3 of rinse
water per day.  Flow through the first rinse booth was measured during the waste stream assessment
period at  1,200 liters per minute. Freshly galvanized pieces are cooled in the second rinse booth.
Flow through this booth nowadays is estimated at approximately 1,200 liters per minute, a reduction
in flow which is due to recent modifications  after the assessment was completed. The rinse booths
operate only when there are  materials to be  rinsed being carried through them.

       Rinsing in a rinse tank, instead of a rinse booth, after galvanizing is the most important step
in decreasing galvanizing water use. Use  of rinse tanks after pickling is also important. The rinse
booths could be replaced by rinse tanks linked in a counter-current flow arrangement. The benefit
of such a system is  that it allows water to be  reused several times before it is discharged to the drain,
in addition to the fact that work pieces are always rinsed using the cleanest water as they leave the
process line.

       A  rinse test was conducted  to verify  the usefulness of the rinse tank concept. This test
successfully demonstrated the feasibility  of continuous-flow rinsing.  Based on the results of the
rinse test,  a continuous rinse  water flow rate of 24 liters per minute (6.3  gal/min) will  remove
pickling acid adequately for two rinse tanks in series.  This flow rate will adequately cool the work,

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preventing the water temperature from rising high enough as to pose a worker safety problem. The
proposed system would use about 35 m3 of water (or less) per day.  This represents a savings of
about 83%.  One of the changes resulting from the study was the replacement of the spray orifices
(nozzles) in the rinse booths by water-saving (low-flow) ones.  This ch'ange resulted in an immediate
reduction in  the water use by 60% and resulted in savings in water use and waste treatment costs of
about $250 per day.

       The cost of the proposed galvanizing equipment changes is estimated at about $70,000, and
ventilation system improvements required to remove pickling solution vapors from the proposed
pickling tank location would cost $25,000.  Due to the expense of the suggested galvanizing changes,
phased  installation was  recommended.   The estimated  payback period  on  the suggested
modifications is about 10 months.

       Galvanizing Chemistry.  Fencing currently is being fluxed twice: once in the preflux tank,
and a second time as it enters the kettle. For galvanizing of objects other than fence panels (such as
building parts), the kettle flux is skimmed to the side and is not used. The kettle flux is 98% ZnCl2
and  contains a small amount of KC1.  Kettle flux adds significantly to the metal content  of
galvanizing rinse water, so discontinuing the use of kettle flux would enhance pollution prevention.

       Prefluxing is crucial in dry kettle galvanizing.  To obtain good fluxing, proper concentrations
of ZnCl2 and NH4C1 must be maintained, and iron and sulfate concentrations must be minimized.
Frequent sampling is required.

       In the preflux chemistry, two terms (i.e., degrees Baume (Be), and Ammonium Chloride
Number (ACN)) are important to the operation of the system.  The Be is a unit of density which is
directly related to the ZnCl2 concentration.  Optimum density ranges from 12 to 15 Be (1.09 g/mL
to 1.12 g/mL), measured at 20C. The ACN of a preflux is  the ratio of the NH4C1 concentration
divided by the concentration  of all other components in solution.  An optimum ACN value is
difficult  to  ascertain.  In U.S.  practice,  recommended values range from  1.17, used  by most
galvanizers,  to 1.8 recommended by Cook (1982). Sjoukes (1990), a galvanizing expert from the
Netherlands, recommends ACN values of 1.75 to 2.5.

       The plant currently collects samples of the preflux solution for detailed analysis, including
ACN, three or four times a year.  More frequent ACN determinations (at least monthly) are needed
for galvanizing strictly by the "dry kettle" method. This becomes more important if the kettle flux
continues to be used after installing the recommended counter-current flow rinse system. This is
because zinc chloride will be dragged into the preflux from the post-pickling rinse.

       In-house testing was recommended  for faster data acquisition. It was also recommended that
a chemist be hired to perform chemical testing on a continuous basis. The same chemist would
conduct tests associated with the electroplating lines, as pointed out above.

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        Additionally, a recommendation was made to the facility to switch from the zinc chloride
 preflux to a mixture of mostly ammonium chloride and some zinc chloride, or ammonium chloride
 alone.  This recommendation was based on the work of Sjoukes (1990).  This would probably
 produce better results by enhancing product quality, since the proposed counter-current flow system
 (with fresh water being added at the final rinse tank) would not complicate preflux chemistry.

        Another problem associated the galvanizing operation was a layer of oil floating on the
 surface of the acid bath. This was not surprising since there was no cleaning stage prior to pickling.
 The oil problem could be minimized  by installing a skimmer system to remove the oil  layer
 periodically. A better alternative is to reduce the amount of oil being left on the work pieces during
 fabricating by careful monitoring of oil  usage during that step.

 The Painting System

        The painting operation at the facility is a sequential system consisting of washing, etching,
 oven drying, spray painting, and oven curing. The paints used at the facility are of the traditional
 solvent-based variety which contain volatile organic compounds (VOC's).  In 1992, the painting
 operation was estimated to have emitted about 37,500 kg (82,500 Ibs)  of xylene,  and 11,000 kg
 (24,200 Ibs) of toluene.  Xylene and toluene are defined as hazardous under the 1990 Clean Air Act
 (CAA), and will be regulated strictly in the near future. Reducing emissions of these VOC's should
 receive a high priority.

        Two major types of paint are in use at the plant. One is a solvent-based paint, which is used
 for painting gates, and the other is a silicone polyester paint used for painting building panels. In
 1992, 74% of paint used by the automatic paint line  was used in painting farm gates. In addition,
 large quantities of a mixture of several aromatic solvents are used for purposes such as cleaning paint
 supply piping. About 2,200 liters (580 gallons) of this  solvent are consumed each month.  A detailed
 analysis of the painting system at this facility is given by Montag (1993).

       Painting  Alternatives. The only  practical way to significantly reduce VOC emissions is to
 change paint materials. There are several possible materials and alternative painting methods to
 consider. One choice is to use water-based paint for gates, which accounts for over 74% of the
 plant's paint use. If water-based paints are applied electrostatically, a high transfer efficiency can be
 obtained. Installation of new spray equipment is the only facility change that will be required, and
 therefore, the investment should be relatively small. Consequently, testing of water-based painting
 alternatives was  recommended for immediate consideration.

       Another method to reduce VOC emissions from painting gates, and also to eliminate chromic
 acid etching of galvanized building panels, is to switch to an autophoretic painting process.  This
 process involves dipping  metal to be painted into tanks filled with paint. Immersion  is required
because the coating is deposited by a chemical reaction between the paint and the metal which takes
 several minutes to occur.  The autophoretic process resembles electrocoating, except that no electric
current is required.  Metal painted by this process reportedly has withstood salt spray tests of up to
3,000 hours without coating failure (Anonymous, 1992). The paint reportedly exhibits a high degree

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of hardness and good resistance to chalking from ultraviolet light exposure. An autophoretic system
to coat gates was estimated to cost about $300,000.  A detailed analysis of this painting method
would be required.  A  serious drawback of this painting  method is that color varies  with the
dissolved iron concentration in the paint, which increases slowly due to contact of the paint with the
steel being painted. Another drawback is the fact that a separate paint tank is needed for each desired
color.

       A third alternative for painting is to consider the use of powder coating.  Agricultural gates
are ideally suited for powder coating because they are made in only two colors. Transfer efficiency
is not an issue in this method because overspray is captured and blended with fresh powder for reuse.
Powder coating would entirely eliminate volatile organics from the paints used for farm gates. An
industrial supply contractor estimated that powder coating could be added to the existing paint line
at this plant for as little as about $40,000.  However, installation costs were estimated to be much
higher than this estimate because the automatic paint line is quite old, and therefore must be replaced
entirely.  A new paint line was estimated to cost about $200,000.

       Pollution prevention in the painting area at this plant will not be offset by significant savings
in terms of  reduced waste disposal costs at the present  time.  However, the Clean Air Act
requirements will soon demand that action be taken. Estimates of the installation costs  for various
painting alternatives are shown in Table 2. As a result of this study, the plant has experimented with
water-based paints as well as a powder coating system.  The facility has requested bids to construct
a powder coating system.
       Table 2.  Summary of costs of painting alternatives at the plant


      	OPTION	COST	

       Water-based Spray Painting                                $25,000

       Autophoretic Coating                                     $300,000

       Powder coating	$200,000	


The Tubing Manufacture System

       A tube mill is used at the manufacturing facility to form metal pipe from coils of sheet steel.
The plant makes the tubing for all its gates, and for sale to other companies. The major tube mill
components include the coil unwinder, the feeder, the initial cold rolls, the welder, the re-galvanizer,
the final  cold rolls, the metering cutter, and the coolant distribution system.
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       A water-based fluid coolant is used by plant for lubrication and cooling of the tube mill.
About 800 liters (210 gallons) of coolant per month are consumed at a cost of about $800. The
coolant flows from its application points into sumps below the components. The sumps, in turn,
drain by gravity to a large collection tank.  The collection tank contains an oil removal system,
consisting of a plastic tube pulled through the liquid coolant. Floating oil adheres to the polyethylene
tube, and is removed by a scraper. The oil removal system is not able to remove oil fast enough.

       The oil in the coolant originates from grease leaking out of the tube mill gearboxes.  Over
the years, oil and grease leaks have covered the tube mill and the surrounding area. Grease combines
with the metal filings created when excess metal is scraped off the fresh welds, and together they
make a black substance that fills the bottom of the sumps in about a month. The mill is occasionally
shut down while operators scoop out all the grease. About two-thirds of the coolant is lost each time
the sumps are cleaned, and this is the only time coolant is discharged from the system.  A detailed
analysis of the tube mill system at this facility is given by Montag (1993).

       Recommended Tube Mill Changes. Recommendations for the tube mill area at this plant are
mostly concerned with changes which would minimize grease contamination of the coolant. The old
oil removal system needs to be replaced and an efficient oil removal system, which should allow the
coolant to be used for several times its current life.  A suitable new oil removal unit was estimated
to cost less than $2,500. The payback period was estimated at less than six months assuming that
the coolant's useable life is only doubled. Beyond that, the  actual payback period could be even
shorter.

       There is also  a  problem with the coolant turning rancid.  Coolant rancidity usually is
controlled by adding one of several possible biocides.  If rancidity problems continue after  an
improved oil removal system is installed, a new biocide may be needed.

       It should be possible to prevent gearbox leakage, or at least reduce leakage from falling into
the  sumps through regular maintenance. Also, preventing metal filings from falling into the sump
below  the weld scraper would keep them from combining with  the grease.  It  was strongly
recommend that the entire area be shutdown for a short period of time for a thorough cleaning. This
would vastly improve the operation of the system. The cleaning should include all equipment, floor
grates, and the return trough.
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SUMMARY AND CONCLUSIONS

       In this report, the preliminary results of an extensive pollution prevention program at a metals
fabricating and finishing facility are reported.  The plant is a large, fairly aged, facility located in the
midwestern United States.  The principal operations involved at this facility include electroplating,
conversion coating, cleaning, machining, grinding, impact deformation, shearing, welding, sand
blasting, hot-dip galvanizing, painting, assembly and testing of various metallic components that are
being made. The discussion in this report has centered on the principal operations that produce the
bulk  of the  wastes  at this  facility including  electroplating, galvanizing, painting, and tube
manufacturing.  Additional information regarding the manufacturing facility and its processes can
be found in Dahab and Montag (1993),  Dahab et al. (1994), Montag (1993) and Parr (1994). (See
the references at the end of this report.)

       This project  has entailed  an extensive and  systematic  waste  stream assessment and
evaluation.  The operations and processes at this  facility result in the production of large quantities
of wastewater with significant concentrations of metals that require expensive treatment. One of the
major constraints in making recommendations was the fact that the facility was fairly old and not
very profitable.  Consequently, all of the  recommendations for process and operational modifications
resulting from the P2 opportunity assessment had to meet critical economic payback periods.

       The pollution prevention recommendations in the  electroplating system,  to date, have
contributed to significant reductions in the amount of wastewater that needs to treated as well as a
significant increase in the product quality.  The product quality increase is clearly demonstrated by
the 550 % and 1000 % increase in the level of protection against white and red rust, respectively, in
the neutral salt spray tests conducted on  the products before and after project implementation. The
plant  management has been quite pleased by these results since numerous claims have been made
against the facility because of corroded fasteners.

       The principal modification to the galvanizing process centered on dramatic reductions in the
amount of wastewater produced  in this process  while improving product quality.  As indicated, it
was apparent that rinse water use could be reduced by as much as 83 percent of what the process was
using prior to the waste stream assessment.  One of the changes resulting from the study was the
replacement of the spray nozzles in the rinse booths by water-saving (low-flow) ones. This change
resulted in an immediate reduction in the water use by 60% and resulted in savings in water use and
waste treatment costs of about $250 per day. The process modifications were estimated to have a
payback period of about  10 months.  Product quality should  improve with  the suggested
improvements in process chemistry.

       Pollution prevention in the painting line was concentrated on reducing VOC emissions which
soon  will be  regulated under the Clean Air Act of 1990. The costs of proposed  modifications
probably could not be justified  in terms of savings  due simply to reduced waste.  Installation
expenses will have to be recovered through adjustments in the pricing of products. However, the
modifications are well justified in terms of expected regulatory requirements.
                                            12

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       The tube mill system was associated with excessive coolant loss as well as rancidity.  The
proposed changes were expected to significantly reduce coolant loss with an estimated payback of
less than six months by installing a better oil and grease removal system. As it turned out, the
facility was able to install a suitable oil removal system for a fraction of the estimate made during
waste stream assessment.
EPILOGUE

       The P2 Opportunity Assessment for the facility conducted in this project also produced
longer-term recommendations  in  addition  to  the  recommendations reported here (see the
Recommendations Reports in the Appendices to this report).  The facility will continue over the
coming months and years to adopt additional recommendations from the assessment.

       For example, subsequent to the implemented changes described above, the company has also:

       (1)     added a new sludge containment area, which conforms to modern RCRA standards
              (compared to the past when they  simply piled up sludge outside until it was hauled
              away);

       (2)     revised their wastewater treatment plant system by installing a new sludge filter press
              to produce much drier sludge than before;

       (3)     with the hiring of the new  chemist (as recommended), the  facility  continues to
              optimize the process lines in both the electroplating and galvanizing lines; and

       (4)     as  of May 1995, the company  indicated that they  were well  on their way in
              revamping the painting lines including the possible purchase of a new power coating
              system.

       In conclusion, implementing pollution prevention and improving facility performance and
profitability will be an ongoing work at this manufacturing site in Nebraska.
                                           13

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REFERENCES

Anonymous. (1992). Steelcase Inc. replaces zinc plating lines, Finishers Management, March, pp.
      17-20.
Cook, T. H., Mergen, D.E., and Clark, D.L. (1986). Increasing profits in hot dip galvanizing, Metal
     Finishing 84(23):23-27.
Cook T.H.  and Horton, W.S. (1982). Ammonium chloride control in galvanizing preflux, Metal
     Finishing 80(19): 19-23.
Dahab,  M.F. and D. Montag. (1993). Waste minimization in a metal-finishing industry: a  pilot
     project,  Presented at the Third  International Conference on Waste Management in the
     Chemical and Petrochemical Industries, Salvador-Bahia, Brazil, October 20-23.
Dahab,  M.F., D. Montag and J. Parr,  1994, "Pollution prevention  and  waste minimization at a
     galvanizing and electroplating facility,"  Water Science and Technology, (In Press).
Durney, L.J. (1984).  Electroplating Engineering  Handbook, Lewis Publishers,  Inc. Chelsea,
     Michigan.
Foecke, T.  (1992). Lecture Notes,  Training  in  pollution  prevention  through  rinsing process
     modifications,   Waste Reduction Institute  for Training  and  Applications  Research,
     Minneapolis, MN. USA.
Hunt, G.E.  (1988). Waste Reduction in the Metal Finishing Industry, Journal of the Air Pollution
     Control Association 38(5):672-680.
Montag, D. (1993). Pollution prevention in the metal finishing industry, Master of Science Thesis,
     University of Nebraska-Lincoln Libraries, December.
Sjoukes, F. (1990). Chemical reactions in fluxes for hot dip galvanizing, Anti-Corrosion Methods
     and Materials 37(4): 12-14.
Parr, J.  (1994). Waste Minimization opportunities for the electroplating industry: a case study,
     Master of Science Thesis, University of Nebraska-Lincoln Libraries, February.
Tsai, E.G. and Nixon, R. (1989). Simple  Techniques for Source Reduction of Wastes from Metal
     Plating Operations, Hazardous Waste & Hazardous Materials 6(l):67-78.
U.S. Environmental Protection Agency. (1990). Guides to Pollution Prevention - The Fabricated
     Metal Products Industry, EPA Report No. EPA/625/7-90/006, July.
U.S. Environmental Protection Agency. (1992). Facility Pollution Prevention Guide, EPA Report
     No. EPA/600/R-92/088, May.
U.S. Environmental Protection Agency. (1993). A Primer for Financial Analysis of Pollution
     Prevention Projects, EPA Report  No. EPA/600/R-93/059, April.
University of Tennessee Center for Industrial Services. (1990). Waste Reduction Assessment and
     Technology Transfer. Second edition, 9/22-9.
Wentz, C.A. (1989). Hazardous waste management, McGraw-Hill Book Company, New York.
                                           14

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APPENDICES
    15

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The Appendices include the following:
                     The interim and final reports on recommendations for implementing
                     P2, which were submitted to Behlen Manufacturing  Company
                     officials.

                     Abstracts and tables of contents of two lengthy and highly technical
                     reports on the project and the technologies considered in the project.
                     (These two reports are referenced at the end of the above report as
                     Montag, D. (1993) and Parr, J.  (1994) and are  available  in their
                     entirety  as Masters  of Science Theses  from the  University  of
                     Nebraska-Lincoln libraries.)

                     An article from the November 1994 issue of Environmental Solutions.
                     (Reprinted by permission of Advanstar Communications Inc.)
                                      16

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INDUSTRIAL POLLUTION PREVENTION PILOT PROJECT
                 An Interim Report
                 Submitted to the

               Behlen Manufacturing
                Columbus, Nebraska
                   Submitted by

              M.F. Dahab, Ph.D., P.E.
                Principal Investigator

           Department of Civil Engineering
            University of Nebraska-Lincoln
              Lincoln, NE 68588-0531
            This Project is funded by the
        U.S. Environmental Protection Agency
                  Office of Water
                 Washington, D.C.

          Steve Wurtz,  EPA Region VII, and
    James Lund, EPA Washington, Project Managers
                 February 8, 1993

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                               INTRODUCTION

      Work began in early 1992 on an industrial pollution prevention pilot project for
Behlen Manufacturing  Company of Columbus,  Nebraska.   The project, which is
partially funded by the  U.S. EPA, is part of an effort by the University of Nebraska-
Lincoln to establish a pollution prevention and waste minimization program throughout
Nebraska.

      Behlen Mfg. Co.  produces fabricated metal parts for farm and industrial uses.
The areas of electroplating, galvanizing,  painting, tubing manufacture, and water use
are being studied for ways to prevent pollution.

      This report begins with a section on electroplating, and then covers galvanizing,
painting, tubing manufacture, water use, and the waste treatment plant. Each of the
sections  describes  the process and  then gives preliminary recommendations for
minimizing  waste production and/or improving product quality.
                        SECTION 1 - ELECTROPLATING

      Behlen currently operates both automated and manual electro- plating lines.
These lines electroplate zinc onto small items such as nuts and bolts which are then
used in the construction of larger products such as fabricated metal farm buildings.
A diagram of each line is included in the appendix section of this document.

Automated Electroplating Process Description

      The automated electroplating line processes an average of 140 pounds of work
per barrel. There are 40 stations on  the line, with an approximate cycle time of 3.5
minutes per station (about 2 hours and twenty minutes total run time per barrel). This
includes a 23 second hang time over the tank to  allow solution to drip off the barrel
before going to the next station. The barrels rotate while in the tank to help keep the
work and solution well mixed.

      Stations  1  and 2 (tanks  1 and 2  -- 200 gallons each) are filled with a soak
cleaner called Metex S 1651 (8 to 12 ounces per gallon of water) and are maintained
at a temperature of 150 to 170F. According to the product information sheet, Metex
S 1651 has a biodegradable surfactant which aids in the removal of dirt and oils from
the surface of the work, and it works in hard water. The cleaner contains 12% sodium
hydroxide,  which  acts to  remove oil from  work  pieces through a saponification


                                      1

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reaction. The sodium hydroxide also breaks down organic compounds and dissolves
amphoteric metals.

      Stations 3 and 4 (tank 3 -- 400 gallons) involve a cleaning process known as
electrocleaning. Electrocleaning works by applying a positive charge to the work and
a negative charge to plates hung at the edge of the tank. Rust, burrs, and smut are
repelled from  the parts, and are attracted to the  negatively charged plates.  The
chemical used in this tank is Metex E 1726 (8 to 12 ounces per gallon of water). The
tank temperature is  maintained at 150  to 170F.  Metex E  1726 is 50%  sodium
hydroxide, and helps to removes oils missed by the soak cleaner tanks.

      The contents  of  the cleaning tanks (soak cleaner  and electrocleaner)  are
discharged to the waste treatment system about every one to four months. The tanks
are dumped if either the  chemical addition  indicated by daily testing equals  the
chemicals needed to  mix a new batch, or if the operator judges that the tank is dirty
and should be changed.

NOTE:  The first eight tanks of the plating line (this includes cleaning,  rinsing, and
hydrochloric acid pickling)  are all emptied at the same time.

      Stations 5 and 6 (tanks 4 and 5 -- 200 gallons each)  involve rinsing the work
with ambient  temperature water to  remove loosened  dirt and oils, and  cleaning
solution dragout. Flow through the rinse  tanks is counter-current (fresh water  flows
into tank 5 overflows into tank 4, and then overflows out to waste treatment  system)
and about 15 gallons per minute is used.  The rinse tanks are cleaned when they are
emptied, and any accumulation of metal sludge is rinsed into the waste treatment
system.

      After rinsing, the barrels continue through the process to stations 7 and 8 (tank
6 -- 400 gallons) where the work is pickled in hydrochloric acid. HCI acts to remove
alkalinity and the thin film of  oxide or tarnish that develops on pieces due to  the
previous cleaning processes. The tank contains about 12% hydrochloric acid  at room
temperature.  Vapor rising from the tank due to the pickling process enters a hood and
is exhausted outdoors.

      Stations 9 and 10 (tanks 7 and 8 -- 200 gallons each) involve rinsing the pieces
with ambient temperature  water to remove all remaining contaminants prior to  the
electroplating process. Flow through the  two  rinse tanks is counter-current at a rate
of about 12 gallons per minute.

      The ninth tank (stations  11 through 30) is the electroplating tank, which holds
5,500 gallons of solution. Work stays in the tank for 20 stations (about 70 minutes).
The electroplating solution contains zinc, potassium chloride, sodium chloride, boric
acid, a  leveling agent, a wetting agent, and a  brightener  at a pH of  about 5. A

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monthly check of the solution is done (by the John Schneider Company) to see if any
chemical additions are needed. Balls of zinc are held in titanium baskets along the side
of the tank.  A potential difference of 8 volts is applied between the zinc balls and the
work pieces (the zinc being positively charged and the work negative). About 1,000
amps  of current is drawn by this process. The current acts to dissolve and  then
deposit zinc from the balls onto the work in the barrel.

      The electroplating solution is circulated through a filter to remove impurities,
and a heat exchanger helps to  cool tank contents to room temperature. The filter is
cleaned in the hydrochloric acid tank on the manual electroplating line and rinsed in
the rinse tank following the HCI tank (also on the manual line).

      Stations 31 and 32 (tanks  10 and 11-- 200 gallons each) involve rinsing the
pieces with water to remove chemicals and loose  zinc particles incurred during the
electroplating process.
Rinse water flow in each tank is approximately 9 gallons per minute. The waste water
drains to the waste treatment plant.

      Tank 12 (station 33) is a drip tank where the barrel hangs above the tank to
allow dragout from  the  rinse  tanks to drip off.  The waste water drains  to the
treatment plant.

      Station  34 (tank 13 - 200  gallons) involves a  yellow chromate conversion
coating process. Tank contents include chromic acid, formic acid, carboxylic acid, anc
nitric  acid at a temperature of 80 F. The barrel  is dipped  into the tank for only 40
seconds during which time a  yellow chromate coating  of  about one half  micron
thickness is deposited on the work. The barrel rotates about 20% of the time while
in the tank compared to continuous rotation at the other stations (this is to prevent
the chromate coating from being knocked off). The chromate tank is disposed of every
three  days, and  prior to entering the waste treatment system, the  chromium VI is
reduced  to chromium III  with  sodium  bisulfite and sulfuric  acid.  Fumes from the
chromate tank and the chromate  rinse tank are collected  by exhaust hoods  and
directed  outdoors.

      Station 35 (tank 14 -- 200 gallons) is a static rinse tank in which the barrel i;>
dipped to remove excess chromic acid solution. This rinse tank is emptied daily. Prior
to emptying, the rinse tank's  contents  must be treated with sodium bisulfite and
sulfuric acid.

      Station 36 (tank 15 -- 200 gallons) is a drip tank to allow dragout from the rinse
tank to drip off (tank contents  must be  neutralized with sodium bisulfite and sulfuric
acid before emptying to waste treatment plant).

      Following  the drip tank, tanks 16  and 17 (stations 37 and 38) are drying areas.

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150F air is blown through the barrels to speed drying of the work inside.

      At stations 39 and 40, the pieces are allowed to cool before being removed
from the barrel. At this point, the empty barrels have come full circle and are ready
to be filled with a new load of work to be electroplated.
Automatic Electroplating Recommendations
      Operation of the soak cleaner tanks can be improved in several ways:

      Temperature should  be  increased from  the current 150 to 170F to the
      temperature recommended by the soak cleaner manufacturer (200 to 205F).
      Tank temperature  and  concentration should  be  monitored  daily.  This will
      improve the effectiveness of the cleaner.

      Fresh water use can be  decreased  by using  water  from rinse tank #4 as
      makeup for the soak cleaner and electrocleaner tanks.

      Filtration could prevent sludge build-up in the bottom of the soak cleaner tanks.
      Raising the temperature and filtering tank contents should improve product
      cleanliness  and increase tank life.

      A grease skimmer and trap should be used to remove grease  and oil from the
      surface of the tank solution to minimize carryover to downstream tanks.
2.    Electrocleaning recommendations are similar to those for the soak cleaners and
      include:

      Increasing temperature to 200F, using a grease skimmer and trap, monitoring
      temperature and concentration daily, filtering solution, and using water from
      tank #4 as  makeup.

3.    Recommendations for the rinsing process after both cleaning and pickling are
      as follows:

      The flow of rinse water through rinse tanks 4, 5, 7, and 8 can be reduced. As
      before, fresh water should enter tank #8, but at a reduced rate of about 0.6
      gallons per minute (gpm) (flow control valves to maintain specific flow rates are
      about 35 dollars -- not installed). The flow is directed counter current into tank
      #7. Water  overflowing from tank #7 would  be directed to tank #5, and then
      countercurrentto tank #4.  Rinse water flow can be cut from a total  of 27 gpm

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      to about 0.6 gpm, a savings of 26.4 gpm. Since it costs about 0.275 cents
      to treat a gallon of waste (based on Behlen estimates), 35 dollars per day could
      be saved. Also, the acid rinsed from the pieces in tank 7 will help to neutralize
      alkalinity from the cleaning tanks (stations 1 through 4) thus increasing the
      effectiveness of rinse tanks 5 and 4.

      NOTE: All  rinse water flow estimates are based on the use of deionized water
      and standard conditions. Flow estimates will increase if tap water is used and
      current housekeeping conditions  prevail.

      A 50 gallon tank could be used to store water overflowing from rinse tank #4.
      This water could  be used as makeup for tanks #1, #2, and #3.

4.    The hydrochloric  acid  tank pH  should be checked  daily to  increase tank
      effectiveness.

5.    Operation  of the electroplating process can be improved in the following ways:

      Electroplating  tank chemistry should  be checked  daily.   Chlorides,  zinc,
      temperature, and  pH should be tested.

      The electroplating solution should be filtered more rapidly to aid in the removal
      of impurities. A typical  plating tank filtration system filters 2 bath volumes per
      hour.

      Air agitation would facilitate better mixing of electroplating tank contents. This
      will improve plating results.

      The use of  anode bags would decrease bath contamination from insoluble
      anode material.

      Perform regular maintenance on  rectifiers, filter system, and barrel and tank
      anodes to optimize plating performance.

6.    The  following  changes are  recommended for the rinsing  and  chromating
      following the electroplating process:

      Eliminate the drip tank prior to chromating (tank 12).  By eliminating the drip
      tank,  tanks #11 and #12 can be used as counter-current rinses with a flow rate
      of about 0.3 gallons per minute (gpm). Tank #10 could then be used as a static
      rinse  (no flow), and the water from this tank could be used as make-up for the
      electroplating  tank. Air agitation of  this still rinse tank would improve rinsing
      efficiency if the plating solution  is highly contaminated. This set  of changes
      should decrease rinse water use from the current level of 17 gpm (combined

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      flow rate for tanks 10 and 11 now) to 0.3 gpm. This would result in a water
      savings of about 8,016 gallons per day, or $22 per day in waste treatment cost
      savings. As previously stated, flow control valves for specific flow  rates are
      available for about 35 dollars.

      NOTE - There is adequate space on the line to move the chromate tank down
      one space (to tank 14) if a drip tank is desired prior to chromating.

      Substituting trivalent chromium for hexavalent chromium should be considered.
      This could help remove a hazardous waste from the process. Chromate  tank
      concentration and temperature should  be monitored daily.
7.    Changes to the process after chromating are as follows:
      A static rinse tank should be used after chromating. A float and pump system
      can be used to withdraw water from the rinse tank to use as makeup for the
      chromate tank.

      A drain board should be installed over the drip tank so that solution falling over
      the tank  is directed back to the rinse tank.
Manual Electroplating Process Description

      The manual electroplating line is more labor intensive than the automated line.
The barrels are hooked onto a chain conveyor system and the operator physically
moves the barrels from station to station using the conveyor system. The barrels are
bigger than those used on the automated line, but the average load of work is still
about 140 pounds. The barrels rotate while in the tanks to promote mixing.

      There is  no  electrocleaning process on this line. Also, a nitric acid tank is
available for pickling stainless steel pieces (this doesn't occur often), and a yellow or
clear chromate  finish may be added after the zinc electroplating process (depending
on customer preference).

      Station 1  (tank 1  -- 600 gallons) is the soak cleaning  station. The tank can
accommodate three  barrels at one time. The barrels are left in the  soak cleaner
solution (Metex S 1651) for about 15 minutes. The process is heated to about 200
F and as stated in the automated section, acts to remove dirt and oil from the work
in the barrel.

      Stations 2 and 3 (tanks 2 and 3-100 gallons) are fresh water rinse stations.
The barrels are  dipped into either tank 2 or tank 3 for a period of about 30 seconds
to remove dragout from the soak cleaning tank. The flow rate through the tanks is 2

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gallons per minute for tank 2, and 7 gallons per minute for tank 3. The barrels hang
over the tank for about 5 seconds and then move to the next station (HCI pickling).

      Station 4 (tank 4 --  200 gallons) is hydrochloric Acid pickling. The barrel is
dipped into this tank for about 10 minutes to remove oxides, tarnish, and  alkalinity.
This tank  is also used to clean the filter from  the electroplating tank pump on the
automated line.  Tanks  1, 2, 3, and  4 are emptied at the same time,  usually about
once every 3 months.

      Station 5  is  a rinse tank (tank 5 -- 100 gallons) used to capture dragout from
the hydrochloric acid tank. The flow rate through this tank is about 7.5 gallons per
minute. The barrel is dipped into this tank for one complete rotation and then removed
(about 10  seconds). This tank is also used to rinse off barrels after being dipped in the
nitric acid tank (station 6), and to rinse the filter from the automated  electroplating
tank.

      Station 6  (tank 6 -- 100 gallons) is the nitric acid tank
which is used to pickle stainless steel parts. This tank is not used very often and is
covered with a heavy piece of plastic between uses.

      Station 7  (tank 7 -- 900 gallons) is the electroplating tank. The chemicals used
are the same as for the automated electroplating tank. There  is no filtering system on
this tank, and the tank solution is checked monthly to determine if chemical additions
are needed. Barrels are dipped into the tank for a period of between 45 minutes to 1.5
hours (depends on customer specifications). The electroplating of zinc onto the work
pieces is similar  to that described for the automated line.

      Station 8  (Tank 9 -- 100 gallons) is a rinse tank  with a flow rate of about 6
gallons per minute. The barrel must be lifted over tank 8 (clear chromate tank) to get
to this rinse tank (the chromate tank is covered  with a heavy  plastic sheet during this
time). This rinse tank is only used to rinse barrels coming from the electroplating tank.

      Station 9  (tank 8 --  100 gallons) is the  clear chromate tank. This solution is
similar to the yellow chromate finish described on the automated line except that it
leaves a clear finish on the  pieces instead of a yellow finish.  This clear finish is used
if preferred by the  customer. The barrel is dipped into the tank for a period of about
3/4 to 1 full rotation (about 10 seconds. It is then allowed to  hang over the tank until
most of the dragout has dripped back into the tank. The barrel is then rinsed in tank
11  for about 20 seconds and then taken to the drying tables (station 12) where the
work is removed and allowed to dry.

      The chromate tank is emptied about once every  6 months. The hexavalent
chromium (Cr VI) is neutralized to trivalent chromium (Cr III) with sodium bisulfite and
sulfuric acid before emptying to the waste treatment  system.

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      Station 10 (tank 10 -- 100 gallons) is the yellow chromate station. It is similar
to the yellow chromate tank described on the automated line (including temperature
of about 80 F).  The barrel is dipped into the tank for about 1 full rotation (about 10
seconds) and then  allowed to hang over the tank until most of the solution dragout
has dripped back into the tank. This yellow chromate finish is used as per customer
preference. The contents are treated as previously described before being emptied to
the  waste treatment system (tank is emptied about once every 4 months).

      Station 11 (tank 11 -- 100 gallons) is a  rinse station used  after a barrel has
been dipped into the yellow or clear chromate tanks. The barrel is dipped into the tank
for about 20 seconds (2 full rotations) and then allowed to hang above until most of
dragout has dripped off. This  is a still rinse tank (flow  is not continuous) and is
emptied about once a month (chromates are neutralized before emptying to the waste
treatment plant.

      Station 12 is a drying area where finished  pieces are taken out of the barrel and
allowed to air dry.
Manual Electroplating Recommendations

1.    All recommendations for the soak cleaning tank are similar to those made for
      the auto line including:

      installation of a  grease skimmer  and  trap, daily  monitoring  of  solution
      temperature (already at 200 degrees Fahrenheit) and concentration, solution
      filtration to remove  sludge build-up, and use of rinse water  from tank #2 to
      make up for evaporation and dragout losses.

2.    Changes recommended for the process after cleaning and before electroplating
      (tanks 2,  3, 4, 5, and 6) are as follows:

      By moving the nitric acid tank next  to the hydrochloric acid tank (tank 5) and
      using one of the empty tanks  at the end of this side of the line  (tank 7)  (see
      figure in appendix for the manual line), it is possible to create two  counter
      current systems that would be  similar to those on the automated line. The fresh
      water flow would originate  in  tank #7 at 0.6 gpm (using flow control valves)
      and then  be allowed to gravity flow to tanks #6, #3, and  finally #2 where it
      could be collected in a 50 gallon tank and used for make-up in the soak cleaner
      tank. This would result in a savings of about 16 gpm (the current 16.5  gpm
      versus 0.6 for the proposed method) and a waste treatment  savings of about
      21 dollars per day.

      Daily testing of the hydrochloric acid tank concentration and pH would optimize


                                     8

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      pickling results.

      NOTE: The use of disposable filters on all filtration systems (especially the Auto
      electroplating tank) will eliminate the use of the hydrochloric acid tank for filter
      cleaning as is currently done. This will  result  in extending the bath life and
      better results in the plating process that follows.

3.    Recommendations for the electroplating tank are similar to those made for the
      auto electroplating tank:

      Daily  monitoring of solution pH, temperature,  total chloride and zinc levels,
      installation of an efficient filtering system to remove impurities and dirt (no filter
      currently  on  this  tank),  air  agitation,  use  of  anode  bags,  and  regular
      maintenance of the  rectifiers, filters, and anodes.

4.    Changes proposed for rinsing after electroplating include:

      A system  similar to  that proposed for the auto  line  should be considered with
      a still rinse immediately after the electroplating tank and 2 counter current
      tanks following with a flow of 0.3 gpm (using flow control nozzles). The still
      rinse could be used  for make-up into the electroplating tank and the rinse tank
      following  the  still  rinse could be used for  make-up into the still  rinse (as
      needed).

      NOTE: This change would entail moving the  clear and yellow chromate tanks
      next to each other. Secure lids would prevent contamination of  one tank while
      the other was being used.

5.    Changes to the chromating process  and rinsing after are as follows:

      The use of trivalent  chrome instead of hexavalent chrome must  be considered.

      As  stated above, secure lids on each of the chromate tanks (clear and yellow)
      would prevent contamination when  barrels pass over the tanks.

      The use of one static rinse tank (no flow) followed by a drip area consisting of
      a drain board (to drain rinse  dragout back into the rinse tank) would be the
      desirable method.
      Recommendations for both Auto and Manual Electroplating Lines

1.  Housekeeping:

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      Conduct a thorough clean-up of the electroplating area, including tanks and
      floor. The dirt, grease and grime that has built up around and in the tanks has
      a detrimental effect on product quality. The placement of lids over the tanks
      when not in use might be beneficial.

      All tanks should be checked for leaks and other potential hazards.

      Establish strict routines for:

      1) regular maintenance of the electroplating area including the equipment used
      (e.g. rectifiers, pumps, heaters, barrels, and barrel anodes)

      2) tank emptying and cleaning

      3) chemical additions to tanks (in between emptying)

      4) regular  testing  of  tank   contents  (in the case  of the  soak cleaner,
      electrocleaner,  electroplating, and chromate  tanks) to make sure they  are
      operating at optimum conditions

      NOTE:  All of the above should be  incorporated  into a written  procedures
      manual for each line.

2.    Hire a chemist to monitor and direct the operation of each line:

      The current operator can run the line but he has no knowledge of the chemistry
      involved in the electroplating process. A person with a thorough understanding
      of how cleaning, rinsing, and  plating work would help create a more efficient
      and cost effective electroplating operation.

3.    Use of deionized water in all  process and  rinse tanks:

      The current water used  (from the Columbus Municipal supply) has extremely
      high values for hardness (300 mg/l as CaC03), alkalinity (304 mg/l as CaC03),
      and TDS (total dissolved  solids) (440 mg/l).  Deionized water would make
      chemical processes (e.g. cleaning and electroplating) more effective and would
      help in the  rinsing process as well. It would also extend the life of the baths
      which would result  in less chemical use.  This should  lead to  a higher quality
      product while decreasing water usage.

4.    Slower withdrawal rates for barrels from the tank solution:

      Current rates are 17  ft/min.  for the automated line  and  27 ft/min.  for the
      manual line.  According to the literature, the  maximum rate for  withdrawal


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      should be about 8 ft/min. This change would help decrease the amount of
      dragout from each tank resulting in decreased chemical usage.

5.    Increase barrel hang time over the tank to decrease-dragout into the next tank:

      The current hang time on the auto line is 23 seconds. There is still significant
      dripping from the barrels after this time period. The hang time over tanks on the
      manual line  varies with operator discretion. For the most part it is minimal or
      non-existent, and dragout is  visually significant. A study must be done to see
      how increasing the hang time affects the dragout rate from the barrels.

      NOTE: It will be necessary to see how increased hang time affects the amount
      of water used per barrel in the rinsing process (since rinse tanks are continuous
      flow).

6.    Decrease flow rates used in  the rinse tanks:

      Combined rinse tank flow rates for both the auto  and manual lines are  64.5
      gallons per minute (gpm). This adds up to a rinse water usage of about 31,000
      gallons per day (based on an 8  hour work day) which must be treated at the
      waste  treatment plant at an average cost of 0.275 cents per gallon (85 dollars
      per day or 22,150 dollars per year).

      Average rinse  water rates  seen in the literature are  10 gpm  for single
      continuous flow tanks and 0.3 gpm  for counter current flow rinses using 2
      tanks (e.g. rinse tanks after  electrocleaning and acid tanks on the auto  line).
      Counter current flow using 2 tanks can contribute  significantly to a reduction
      in water use. Currently the rinse system uses between 2 and 15 gallons per
      minute per tank, with the two  counter current systems (after  the soak and
      electrocleaner tanks, and  the acid tank) using  15 and  12  gpm respectively.

      Note: It may be necessary to delay implementation of this recommendation
            until after deionized water is  used which will improve the effectiveness
            of the rinsing process.
                            Section 2 - Galvanizing

      Galvanizing is a  five step  process  consisting of pickling,  rinsing, prefluxing,
galvanizing, and final rinsing. The next few paragraphs describe galvanizing in greater
detail.
                                     11

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Pickling

      Pickling prepares work  for galvanizing by  removing oxides from the  steel
surface.  The pickling tank is maintained at a temperature of 155 to 160  degrees
fahrenheit.  It holds a  10% (by weight) sulfuric acid bath, which is inhibited with
Rodine 85.  The work  pieces are  dipped in the pickling acid  for varying lengths of
time, and then taken away to be rinsed.

      Pickling time is very important because, while the time must be sufficiently long
to remove oxides, excessive pickling can dissolve the base steel. The "proper" time
depends  on how much  mill-scale is  present, and  is chosen based  on operator
experience.  Fencing is pickled for 5 to 10 minutes.

      Pickling consumes  17,000 pounds  of 66 degree Baume sulfuric acid  each
month.  Some of the acid is lost by evaporation and drag-out, but most of the acid
used is hauled away as hazardous waste. The pickling tank is emptied once every five
weeks, due to  the  slow rate of pickling when  the  acid becomes spent.  Envirite
Corporation of  Harvey, Illinois hauls away the used pickling acid, and  recycles it.
Envirite charges Behlen $5,500 each time the pickling tank is emptied.

      Behlen has purchased a sulfuric  acid recovery system to recycle the acid bath
contents.  The  acid recovery system is installed and operating.  It precipitates iron
sulfate and zinc sulfate by cooling the pickling solution. Operating principles of the
system  are explained  in  an  attached summary, which  was published  by the
manufacturer.

      The pickling tank contains a small amount of  Rodine 85, an inhibitor. Inhibitors
are chemicals which minimize acid attack on the base metal during pickling.  Page 9
of Pickling of Steels (Mulcahy, 1973) explains inhibitor action.

      Rodine 85 is composed of 40-50% substituted triazine, 1-5%  thiourea,      -1
10% hydrochloric acid, < 1 % formaldehyde and <  1 % ortho toluidine. 1.5 gallons of
Rodine 85 are added to each fresh tank of acid, and a total 60 gallons of Rodine 85
are used each year.  The recovery system does not remove inhibitor, so less inhibitor
will be used in the future.
Rinsing

      After pickling, the work is rinsed with city water to remove all pickling acid.
The preferred rinsing method is to dip work pieces in the rinse tank, which is filled
with unheated city water. The rinse water is agitated by moving the crane back and
forth while the work is submerged. When pickling is finished, the work is withdrawn,
and held over the  rinse tank to allow excess  water to drip off before going to the

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preflux tank. The steel surface must not be allowed to dry completely, or oxidation
will result.

      As  could  be  expected,  contaminants  build up in the rinse tank.  A recent
analysis of rinse tank water indicated that it contains 297 mg/l total iron and 473 mg/l
total zinc. In order to prevent excessive buildup of chemicals in the rinse water, 2000
gallons from the rinse tank are emptied to the waste treatment plant each week.
Alternate rinse

      The rinse booth located between the pickling tank and the rinse tank can be
used as a substitute for the rinse bath.  Operators say the rinse tank water is too
dirty, so the rinse  booth  is almost always used (fencing is  rinsed for  about 17
seconds). The  booth drains directly to the treatment plant without storing water for
further use.  Flow  rate  through the rinse  booth  was recently measured by David
Montag at 300 gallons per minute.
Prefluxing

      After the first rinsing comes prefluxing, which is a crucial step in the dry kettle
galvanizing process. The work is coated with flux chemicals prior to entering the zinc
kettle. The preflux tank is kept at 160 degrees fahrenheit, and is filled with water
containing  zinc chloride and  ammonium chloride.  Work  pieces are dipped  in the
preflux tank and withdrawn. The preflux solution should be allowed to dry thoroughly
before proceeding with galvanizing.

      Behlen uses 1,006 pounds  per month of  zinc  ammonium chloride mixture
(ZnCI2-2NH4CI with 56 wt%  ZnCI2 and 44 wt% NH4CI), and about 482 pounds per
month of additional ammonium chloride is used.

      To obtain good fluxing, proper concentrations of zinc chloride and ammonium
chloride must be maintained, and iron and sulfate concentrations must be minimized.
Frequent sampling is  required for  good chemistry  control.  Preflux sampling and
sample frequencies are described below.

      Two of the terms used in preflux chemistry may be unfamiliar to the reader.
These terms are degrees Baume (Be), and Ammonium Chloride Number (ACM).  Be
is a unit of density, and any density expressed in Be  can be converted to other, more
familiar, units.  A density conversion table is included in the appendix.

      The  preflux  density depends almost  entirely on ZnCI2 concentration.  The
desired density  range is about 1 2 to 1 5 Be (1.09 g/ml to 1.12 g/ml) measured at 70


                                     13

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to 75F.

      The ACN of a preflux is a  ratio of the NH4CI concentration divided by the
concentration of all other components in the solution. Opinions about the best ACN
differ: Mineral Research Corporation recommends 1.17, Dr. T.H. Cook recommends
1.4 to 1.8, and Sjoukes recommends 1.75 to 2.5.

      Mr. Richard Robak,  the  galvanizing  team leader,  draws all preflux samples.
Density is checked daily, and iron and sulfate samples are drawn every 3 to 4 days.
Behlen's maximum specification for iron is 1 %, and the max for sulfate is 1.5 to 2%.
Every three or four months, Mr. Robak sends a preflux sample to Mineral Research
Development Corp. of Charlotte, N.C.. Mineral Research performs a detailed analysis,
including ACN determination.

      A detailed preflux analysis was performed on a sample drawn on 6/16/92.  The
density was 15.99 degrees Baume, and the ACN was 0.92.  This means that Behlen's
flux has more zinc chloride than necessary and too little ammonium chloride.  A low
concentration  of  ammonium  chloride in the preflux causes poor  fluxing  for dry
galvanizing (Cook, 1982; Sjoukes, 1990). The low ACN indicated by Behlen's most
recent preflux  sample analysis should be corrected immediately.   A letter from Mr.
Mark Keffer of Mineral Research to Mr. Dick Robak  of Behlen recommends adding
more ammonium  chloride to Behlen's preflux.  Mr. Keffer's letter is included in the
appendix. Other suggested chemistry changes are given at the end of the galvanizing
section.
Galvanizing

      Galvanizing is accomplished by immersing steel in a tank filled with molten zinc
for 2 to 3 minutes. Livestock fencing, the majority of the steel being galvanized, uses
the wet kettle galvanizing method. This means that a flux layer floats on top of the
galvanizing kettle.  A flux layer covers the kettle, and work pieces pass through the
layer when entering and leaving the kettle.  For galvanizing other than fence panels,
such as building parts, the kettle flux layer is skimmed to the side and not  used.

      The flux used by Behlen is called Preact, and is supplied by Mineral Research
Corporation.  Preact is 98% zinc chloride, and contains a small amount of potassium
chloride. Behlen uses 16,300 pounds of Preact flux per month.  Fencing galvanized
without using the  kettle  flux always comes  out covered with sharp zinc  "icicles".
Since the icicles could cut farm animals, the smoother finish obtained by using a kettle
flux is  considered necessary.
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                               POLLUTION PREVENTION

             AT AN AGING MIDWESTERN MANUFACTURING FACILITY
        This report  describes the results of  an  Industrial  Pollution Prevention  Project (IP3)
 demonstration project in Nebraska.  The goal of the project was to demonstrate the adoption of
 pollution prevention (P2) practices by a rural and aging manufacturing facility.

 INTRODUCTION

        The manufacturing facility is located in a predominantly agricultural area. The plant site is
 a 100 acre area on which several buildings are located -- the largest of which is the manufacturing
 facility (805,000 square feet).  The facility produces fabricated metal products for farm and industrial
 uses including structural steel members and plates, farm gates, fencing, and livestock watering tanks,
 in addition to a wide variety of structural bolts, fasteners,  etc.   Because of the nature of its
 manufacturing, the facility is licensed as a hazardous waste generator and is permitted under the
 RCRA and NPDES systems.

        In its various manufacturing processes, the facility performs many operations including
 electroplating, conversion coating, cleaning, machining, grinding, impact deformation, shearing,
 welding, sand blasting, hot-dip coating, painting, assembly and testing.  Many of these processes
 result  in the production of a variety of pollutants that have  to be disposed of in some fashion
 depending on their nature.  For example, the electroplating line results in the production of acids and
 rinse water containing zinc and chromium, and the hot-dip galvanizing process results in the
 production of acids and rinse water containing zinc, lead, and iron, which must be treated as a
 hazardous substance containing heavy metals.  The painting processes result in the production of
 used industrial cleaners, acids, solvents, and chemicals used in the cleaning and degreasing of metal
 components.

       All process wastewaters produced at this facility are treated in accordance with stipulations
 of the discharge permit. The wastewater is treated by lime and polymer addition and pH adjustment
 before discharge.  In the past, waste disposal at this facility has resulted in potential problems to both
 surface and ground water resources in the area. The waste disposal systems at the facility  constitute
 a major expense.  The management at the facility  recognized that the economic viability of the
 facility depended on reducing pollution control expenses and lowering or eliminating the  burden of
 regulation the company must endure.

P2 OPPORTUNITY ASSESSMENT

       A work plan for the  P2 assessment program was developed identifying several tasks,
including:

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     1. Development  of  a detailed  assessment  and  evaluation  of current  practices and
        characterization of all wastes produced by the facility.

     2. Identification and delineation of all possible P2 opportunities.

     3. Economic and technical evaluation of all waste prevention and minimization alternatives
        including short-term as well as long-term impacts of these alternatives.

     4. Development of recommendations to be made to the management of the  manufacturing
        facility for P2 implementation that would be based on economic priority in terms of greatest
        benefit and shortest pay-back periods.

     5. Providing technical assistance, where appropriate, during the process of implementation
        of the recommended alternatives.

     6. Review of the results and impacts after implementation of the recommendations.

       In  developing the work  plan, a multi-media  approach was  emphasized  in  developing
pollution prevention and minimization strategies affecting all operations and processes.
The waste stream evaluation process conducted at the facility followed procedures outlined by the
U.S. Environmental Protection Agency (see References  section at the end of this report: U.S. EPA,
1990; 1992; 1993).

       In  conducting the P2 opportunity assessment, emphasis became focused on finding those
areas where the impact on reducing the total pollutant  load produced  by this facility could be the
greatest. Those areas were the electroplating, hot-dip galvanizing and  the painting lines as well as
the tube-mill production area. Because these areas produced the bulk of the wastes with the greatest
toxicity and hazard, it was judged that improvements in  these areas  would produce the greatest
impacts.

The Electroplating Systems

       The manufacturing facility operates both an automated line and  a manual electroplating line.
These lines are used to deposit a thin zinc film onto small items such  as bolts, fasteners and nuts,
which  are then used in the construction of larger  plant products such as  farm buildings. The
automatic  electroplating line is a barrel system which plates about 65 kgs (145 Ibs) of work per load.
The barrels are moved by a conveyor chain.

       The automated electroplating line processes an  average of 65 kgs (145 Ibs)  of work pieces
per barrel. There are 36 stations on the line, with an approximate cycle time of 3.5 minutes at each
station (about two hours per barrel).  The work is first cleaned  in  a  soak cleaner and  an
electrocleaning solution. It is then rinsed, pickled in  a hydrochloric  acid bath, and rinsed again
before going into a chloride-zinc electroplating bath. After residing  in the plating bath for about an
hour and ten minutes (20 stations), the work is rinsed. A light yellow chromate finish is added. A

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short rinse (20 seconds) follows the chromating process after which the work is dried at 65C
(150F).  The electroplating solution is circulated through a filter to remove impurities. Particles
removed by the filter are rinsed into the treatment system. The total rinse water use in the automatic
electroplating line at this facility was estimated at 166 liters per minute (20 gpm) during 8 hours of
operation daily.

       The manual process is more operator intensive, which requires hand moving of barrels from
station to station.  The barrels are bigger, but the average load of work per barrel is also 65 kgs (145
Ibs). This line is used more often than the automated line, especially when small quantities need to
be plated. The work is cleaned in a soak cleaning bath (no electrocleaning) for about  15 minutes.
It is then rinsed, pickled in hydrochloric acid, and rinsed again before being placed in the chloride-
zinc electroplating tank (stainless steel pieces are dipped in nitric acid, instead of hydrochloric acid).
The work pieces are plated for an average  of 1 to 1.5 hours before being removed from the tank. A
short rinse precedes the chromate coating; which can be clear or yellow, depending on customer
preference.  After a final short rinse, the pieces are placed on a table to air  dry. A more detailed
analysis of these electroplating lines is given by Parr (1994).

       Pollution Prevention Opportunities in the Electroplating Systems

       House Keeping Practices. To obtain better product quality and assure that the lower flow
rates will not compromise rinsing efficiency, it was recommended that housekeeping practices be
changed.  There needed to be a thorough cleaning of the electroplating area including all tanks
(inside and out), floor, and all equipment related to the electroplating process. A system needed to
be established for recording when maintenance is done, tanks are emptied, chemicals are added, and
testing on tank parameters is performed (e.g. pH, temperature, chemical concentration).

       Rinse Water Use.  The suggested process  changes were designed to reduce waste of both
rinse water and electroplating chemicals.  To achieve these reductions, improved cleanliness and
more careful chemistry control were required. It was recommended that the rinse rates be reduced
to decrease  the amount of wastewater being discharged to the treatment plant.  For both the
automated and manual electroplating lines, reactive rinsing was recommended in order to decrease
water use from the rinses following the  acid dip (pickling) and alkali cleaning processes (Tsai and
Nixon, 1989; Hunt,  1988).  Water from the rinse after pickling would no longer go down the drain,
but would instead flow to the rinse tanks following alkali cleaning.  Rinse water flow calculations
showed that for these two processes, the required flow on each line could be as low as 8 liters per
minute (2 gpm) (Durney, 1984).

       At this plant, it was found that the effluent  from the rinsing step after the acid dip could be
directed to the rinse tanks after the cleaning process. This change would save  a total of about 76 m3
(20,000 gal.) of water per day resulting in  a cost savings of about $150 per day in waste treatment,
sludge disposal, and water costs. Counter-current tanks similar to those on the automated line (after
the cleaning and acid dip processes) would be needed on the manual line to incorporate this change.
The cost  of these counter-current tanks  was estimated at $ 1,000.

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       It was  recommended that the rinse processes after the electroplating tanks on both the
automatic and manual lines be changed to counter-current with a rinse flow rate of 20 liters per
minute (5.3 gpm) each.  About 24 m3 (6,400 gal.) of water per day can be saved, resulting in a cost
reduction of $50 per day. The cost associated with these changes was estimated at $1,000 for the
counter-current tank system.

       Electroplating Chemistry. The testing of chemical and operating parameters in the  tanks
needed to be done on a daily basis for several variables. Electroplating tank variables included pH
and temperature in addition to the concentrations of cleaners, acid dips, zinc metal, boric acid, total
chlorides, and the wetting agent.  Chromating tank variables included pH, temperature, and chromate
concentration.

       Other Changes.  Other recommended changes that were needed to improve the process
included increasing the temperature of the cleaning tanks on the automatic line from 71 C to  93 C
(160F to 200F). It was noted that a certain amount of grease originating at the machining steps
of bolt production was accumulating in the automatic electroplating line's cleaning tanks.  Grease
skimming from the  top of the cleaning tanks needed to be  improved to remove more of the grease
and  oil before it carries  over into the  downstream  processes.   The  filtering system  on the
electroplating tanks needed to be repaired, as it was inoperative. Once the filtering system is repaired
(on both lines), it  should be possible to determine if these  systems are adequate to maintain
contaminants at proper low levels.  In fact, it was recommended that a new filtering system be
installed.

       It was noted  that anode bags should be used to keep contaminants and dirt from the zinc balls
out of the electroplating solution. Also, a drain board needed to be installed over the drip tank after
the chromate rinse (on the auto line) to direct all dragout back into the rinse tank.

       By using a trivalent chrome conversion coating  process instead of the hexavalent chrome
process that was being used, the facility should reduce the toxicity of the waste produced. Lower
treatment costs would be realized since hexavalent chrome must be chemically reduced  to its
trivalent form, which is less expensive to treat, before  sending it to waste treatment plant. The
potential disadvantages of these changes  would be: a slight reduction in corrosion protection, the
need for closer monitoring and testing of the process, and that trivalent chrome coats are only
available in a bright blue color instead of the customary light yellow.

       To recapture some of the chemical dragout from the electroplating and chromating, it was
recommended that still rinse tanks be used after these processes. It is estimated that about 50% of
the chemical  lost  to dragout can  be  recaptured by  this method  (Hunt,  1988).  It was also
recommended that air agitation be used in the  tanks to increase rinsing efficiency.

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       The electroplating process should be supplied with as clean a water as possible. It was noted
that the facility had a reverse osmosis (RO) purification unit which was not in use, so it was
recommended that the RO unit be used to supply water to the electroplating, chromating, and still
rinse tanks. This change would remove potential contaminants in tap water including total dissolved
solids (TDS) and hardness, thereby increasing  process efficiency.

       The barrel withdrawal rates were measured at 5.2 m/min (17 ft/min) in the automated line
and 8.2 m/min (27 ft/min) in the manual  line.  According to Foecke (1993), the maximum rate of
withdrawal should be about 2.4 m/min (8 ft/min). This change would help decrease the amount of
dragout from each tank resulting in decreased chemical usage.

       It was also recommended that the hang time of the barrels over the tanks be increased by
pausing longer before moving to next station.  The barrel hang time on the auto line was 23 seconds.
There was still significant dripping from the barrels after this time period.  The hang time over tanks
on the manual line  varied according to  operator discretion.  For the most part, hang time was
observed to be minimal,  and dragout was consequently significant.

       Results of Implemented Changes in The Electroplating Systems

       Recommended changes to the automatic electroplating line were presented to the facility. To
date, four recommendations have been implemented, the results of which are summarized in this
section.

       The first recommendation to be implemented was to clean the outside and inside of all the
tanks on the plating line and remove bottom sludge that had developed.  In particular, the bath
contents of the electroplating tank were pumped into a temporary holding tank and the bottom sludge
was shoveled into eight 55-gallon drums  for disposal (this sludge is not listed as hazardous under
RCRA regulations). The liquid  portion of the plating bath was then pumped back into the plating
tank and additional chemicals and water were added to restore them to normal levels.

       Another recommendation that was implemented was regular testing of the cleaning, acid dip,
electroplating, and chromating processes to maintain chemical  concentrations at their optimum
levels.

       The third  implemented  recommendation  was the hiring of an employee with suitable
chemistry background to perform operational control testing (among other duties including the
galvanizing system chemistry, as discussed below) and report results back to the plating operator so
that any required chemical additions can be made. The results of this testing are being  documented,
and chemical additions are now being made on a regular basis.

       The fourth implemented recommendation was the reducing of all rinse flows.  Flow control
devices have been installed on the rinses after the alkaline cleaning and acid dip  processes to
maintain flow rates at the recommended levels.  The two systems have not been connected together
as was recommended. The flow rate for the two rinses after electroplating also have been reduced,

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although neither a countercurrent system nor flow control devices have been installed. The new rates
have not been measured, and it has also not been determined if they are being maintained at a
consistent level.  According to the plating operator, the valves controlling flow are not turned on as
far as in the past.  The flows still appear to be above recommended levels (as judged by visual
observation), but until flow control valves are installed or some other way of producing a consistent
flow is devised, the current method will be continued.

       The implemented changes also have resulted in significant product quality increases as
evidenced by the results of the 5% neutral salt spray testing (as per ASTM B-l 17) done on bolts
plated on the automated line before and after the changes were initiated.  These results are presented
in Table 1 below, and show a 1,000% increase in white rust protection and a 550% increase in red
rust protection.
       Table 1.  Results of 5% neutral salt spray tests
Parameter
Hours to White Rust
Hours to Red Rust
Pre-Change
Results
16
48
Post-Change
Results
168
264
Typical
Values
96 - 250
200 - 350
       In conclusion, the facility has been very encouraged by these positive results. Also,
from a waste prevention and minimization  perspective, the  implemented changes have  been
effective.  The reduction in rinse flows will no doubt lead to less wastewater needing to be treated
at the waste treatment plant. The cleaning of tanks, removal of sludge, and use of oil absorbent pads
on the cleaning baths should help reduce the drag-out of dirt,  grease, and other contaminants to
downstream processes. This will help to increase bath life which  will result in fewer bath dumps and
reduced chemical use.  The costs associated with these implemented changes have been modest.

The Galvanizing System

       The galvanizing process at the facility is a five-step procedure consisting of pickling, rinsing,
prefluxing, galvanizing, and final rinsing.  The  pickling step  prepares work for galvanizing by
removing oxides from the steel surface using a 10% sulfuric acid solution at a temperature of 70C
(158F). The work pieces are dipped in the pickling acid for varying lengths of time, and then taken
away to be rinsed.

       After pickling, work pieces are rinsed to remove the acid.  The preferred rinsing method is
to dip work pieces in the rinse tank, which is filled with unheated municipal water.  The rinse water
is agitated by moving the work pieces back and forth in the rinse tank.

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       After the first rinsing, work pieces are placed in the preflux tank, which is a crucial step in
the "dry kettle" galvanizing process. The work is coated with flux chemicals (ZnCl2 and NH3C1)
prior to entering the zinc kettle.  The preflux tank is kept at 70C. Normally, the preflux solution
should be allowed to dry thoroughly before proceeding with galvanizing.

       Galvanizing is accomplished by immersing steel in a tank filled with molten zinc for 2 to 3
minutes.  Livestock fencing, the majority of the steel  galvanized at this plant, uses the wet kettle
galvanizing method. This means that a flux  layer is floated on top of the galvanizing kettle. A flux
layer covers the kettle, and work pieces pass through it as they enter and leave  the kettle.  For
galvanizing other materials such as building  components, the kettle flux layer is skimmed to the side
and not used.

       The work pieces are cooled by rinsing them in a second  rinse booth located next to the
galvanizing kettle.  This final rinse is needed to cool the work to below 200C (390F), which stops
the possible growth of a brittle zinc-steel alloy layer. Cooling also makes it easier  for operators to
handle the work pieces.  A detailed analysis of the galvanizing  system at this facility is given by
Montag(1993).

       Pollution Prevention Opportunities in the Galvanizing Process

       Pollution prevention efforts in the  galvanizing area were concentrated on  reducing the
volume and metal content of rinse water since this is the principal medium through which metal is
lost. Volume reductions can be accomplished by installing additional galvanizing equipment. Metal
content reductions are possible by  either discontinuing use of  the kettle flux, or switching to a
different kettle flux.

       Rinse Water Use. The galvanizing system at this plant initially used about 265 m3 of rinse
water per day.  Flow through the first rinse booth was measured during the waste stream assessment
period at  1,200 liters per minute. Freshly galvanized pieces are cooled in the second rinse booth.
Flow through this booth nowadays is estimated at approximately 1,200 liters per minute, a reduction
in flow which is due to recent modifications  after the assessment  was completed. The rinse booths
operate only when there are materials to be  rinsed being carried  through them.

       Rinsing in a rinse tank, instead of a rinse booth, after galvanizing is the most important step
in decreasing galvanizing water use.  Use  of rinse tanks after pickling is also important. The rinse
booths could be replaced by rinse tanks linked in a counter-current flow arrangement. The benefit
of such a system is that it allows water to be  reused several times before it is discharged to the drain,
in addition to the fact that work pieces are always rinsed using the cleanest water as they leave the
process line.

       A  rinse test was conducted  to verify  the usefulness of the rinse tank concept. This test
successfully demonstrated the feasibility  of continuous-flow rinsing.  Based on the results of the
rinse test,  a continuous rinse  water flow rate of 24 liters per minute (6.3  gal/min) will  remove
pickling acid adequately for two rinse tanks in series.  This flow rate will adequately cool the work,

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preventing the water temperature from rising high enough as to pose a worker safety problem. The
proposed system would use about 35 m3 of water (or less) per day. This represents a savings of
about 83%. One of the changes resulting from the study was the replacement of the spray orifices
(nozzles) in the rinse booths by water-saving (low-flow) ones. This ch'ange resulted in an immediate
reduction in the water use by 60%  and resulted in savings in water use and waste treatment costs of
about $250 per day.

       The cost of the proposed galvanizing equipment changes is estimated at about $70,000, and
ventilation system improvements required to remove pickling solution vapors from the  proposed
pickling tank location  would cost $25,000. Due to the expense of the suggested galvanizing changes,
phased  installation  was  recommended.   The estimated payback  period  on  the suggested
modifications is about 10 months.

       Galvanizing Chemistry. Fencing currently is being fluxed twice: once in the preflux tank,
and a second time as it enters the kettle.  For galvanizing of objects other than fence panels (such as
building parts), the kettle flux is skimmed to the side and is not used. The kettle flux is 98% ZnCl2
and  contains a small amount of KC1.  Kettle flux  adds significantly to the metal content of
galvanizing rinse water, so discontinuing the use of kettle flux would enhance pollution prevention.

       Prefluxing is crucial in dry kettle galvanizing. To obtain good fluxing, proper concentrations
of ZnCU and NH4C1 must be maintained, and iron and sulfate concentrations must be minimized.
Frequent sampling is  required.

       In the preflux chemistry, two terms (i.e., degrees Baume (Be), and Ammonium Chloride
Number (ACN)) are important to the operation of the system. The Be is a unit of density which is
directly related to the ZnCl2 concentration.  Optimum density ranges from 12 to 15 Be (1.09 g/mL
to 1.12 g/mL), measured at 20C. The ACN of a preflux is the ratio of the NH4C1 concentration
divided by the concentration of  all  other components  in solution. An optimum ACN value is
difficult  to ascertain.  In U.S. practice, recommended values range  from 1.17, used by most
galvanizers, to 1.8 recommended  by  Cook (1982). Sjoukes (1990), a galvanizing expert from the
Netherlands, recommends ACN values of 1.75 to 2.5.

       The plant currently collects samples of the preflux solution for detailed analysis,  including
ACN, three or four times a year. More frequent ACN determinations (at least monthly) are needed
for galvanizing strictly by the "dry kettle" method. This becomes more important if the kettle flux
continues to be used after installing the recommended counter-current flow rinse system.  This is
because zinc chloride will be dragged into the preflux from the post-pickling rinse.

       In-house testing was recommended for faster data acquisition. It was also recommended that
a chemist be hired to perform chemical testing  on a continuous basis.  The same chemist would
conduct tests associated with the electroplating lines, as pointed out above.

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Pilot project adds  polish
to  metal finisher's
pollution prevention  efforts
BY M.F. DAHAB AND JIM LUND


      AN AGING MIDWESTERN MANUFAC-
      turing facility that produces fabricated
      metal products for farm and indus-
      trial uses was chosen as the site for an
      industrial pollution prevention and
waste minimization pilot project The project
goal was to demonstrate that using appropri-
%ate management and operating procedures
can reduce the total pollution produced by an
industrial operation. The facility is a licensed
hazardous waste generator.
  The plant engages in a variety of pollu-
tion-generating activities, including electro-
plating, conversion coating, cleaning,
machining, grinding, impact deformation,
shearing, welding, sand blasting, hot-dip
coating, painting, assembly and testing. The
hot-dip galvanizing process results in pro-
duction of rinsewater containing such heavy
metals as zinc and iron. Painting processes
generate used industrial cleaners, acids, sol-
vents, and chemicals used in cleaning and
degreasing metal components.
   Process wastewaters are treated by adding   tion and minimization opportunities;
lime and polymer, and adjusting pH before      Evaluating economic and technical
discharge. Past disposal practices at the facil-   aspects of waste prevention and rninimiza-
ity had threatened area
surface and groundwater.
Waste disposal is a major
operating expense.
  Procedures and
methods. The waste-
stream evaluation fol-
lowed Environmental
Protection Agency guid-
ance. A pollution pre-
vention assessment work
plan identified several
tasks, including:
    Developing  a
detailed assessment and
evaluation of current
practices, and characteri-
zation of all wastes pro-
duced by the facility,
   Identifying possible pollution preven-
Past disposal
practices at he tacity
bad threatened area
surface and ground-
water. Waste fcposal
is a major operating
expense.
              tion alternatives, and
              their short- and long-
              term impacts;
                 Developing rec-
              ommendations to man-
              agement       for
              implementation based
              on greatest benefit and
              shortest payback peri-
              ods;
                 Providing techni-
              cal assistance during
              implementation of rec-
              ommended alternatives;
              and
                 Reviewing the
              results and impacts on
              waste prevention after
implementing the alternatives.
  In developing the pilot project:, empha-
            Reprinted with permission from the November 1994 issue of Environmental Solutions.
            Copyright 6 1994 Advanstar Communications Inc.

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sis was placed on areas in which the impact
on reducing total pollutant load would be
greatest  the electroplating, hot-dip gal-
vanizing and painting lines, and tube-mill
production areas. Strategy development
stressed a multimedia approach to prevent-
ing and minimizing pollution.
   Electroplating systems. The facility
operates an automated and a manual elec-
troplating line to deposit a thin zinc film onto
such items as bolts, fasteners and nuts, which
are used to construct larger plant products.
The automatic line is a barrel system that
plates about 145 pounds of work per load.
Barrels are moved by a conveyor chain. An
average of 145 pounds of pieces per barrel
are processed by 36 stations on the line. The
cycle takes about 3.5 minutes per station, or
about two hours per barrel.
   The work first is soaked in cleaner and
an electrocleaning solution. It then is rinsed,
pickled in a hydrochloric acid bath, and
rinsed again before entering a chloride-zinc
electroplating bath. After about an 70 min-
utes in the plating bath (20 stations), the
work is rinsed, and a light yellow chromate
finish is added. A short rinse  (20 seconds)
follows the chromating process, after which
work is dried at 65 degrees Celsius.
   The electroplating solution is circulated
through a filter to remove impurities, which
are rinsed into the treatment system. Total
rinsewater use in the automatic electroplat-
ing line, which operates eight hours a day,
was estimated at 166 liters per minute.
   The manual process requires operators
to move barrels from station to station. The
barrels are bigger, but the average load of
work per barrel is the same as in the auto-
mated process. The manual line is used more
than the automated line, especially when
plating small quantities. The work is cleaned
in a soak cleaning bath (no electrocleaning)
for about 15  minutes. It then is rinsed, pick-
led and re-rinsed before entering the chlo-
ride-zinc electroplating tank (Stainless steel
pieces are dipped in nitric acid instead of
hydrochloric acid.) Pieces are plated 60 to
90 minutes before being removed. A short
rinse precedes the chromate coating, which
can be clear or yellow. After a final short
rinse, pieces  are placed on a table to dry.
   To obtain better product quality and
ensure that the lower flow rates would not
compromise rinsing efficiency, housekeep-
ing changes were recommended. These
included a thorough cleaning of the elec-
troplating area (tanks, floor and electro-
plating process  equipment),  and  a
maintenance recordkeeping system.
   The suggestions, designed to reduce nn-
sewater and electroplating chemical waste,
called for improved cleanliness and better
chemistry control. Also recommended was
reducing rinse rates to decrease the amount
of wastewater discharged to the treatment
plant. Reactive rinsing was recommended
for both electroplating lines to decrease water
     Use of still rinse tanks
     (olio wing electroplating
     and chromating was
     recommended to
     recapture some of the
     chemical dragout from
     these processes.
use from the rinses following pickling and
alkali cleaning. Pickling rinsewater no longer
would go down the drain, but instead flow
to rinse tanks following alkali cleaning.
   Effluent from the rinsing step after the
acid dip could be directed to the rinse tanks
after the cleaning process, saving about 76
cubic meters of water and $150 per day in
waste treatment, sludge disposal and water
costs. Countercurrent tanks similar to diose
on the automated line would be needed on
the manual line to incorporate this change, at
a cost of about $ 1,000. It was recommended
mat rinse processes following electroplating
on both lines be changed to countercurrent
widi a rinse flow rate of 20 liters per minute
each. About 24 cubic meters of water a day
can be saved, saving $50 per day.
   Daily testing of chemical and operating
parameters in the tanks needed to be per-
formed for several variables. Electroplating
tank variables included pH and temperature
in addition to concentrations of cleaners, acid
dips, zinc metal, boric acid, total chlorides
and the wetting agent Chromating tank vari-
ables included pH, temperature and chro-
mate concentration.
   Other recommended changes included
increasing the temperature of automatic line
cleaning tanks from 71 degrees Celsius to
93 degrees Celsius. Grease skimming needed
improvement, because grease originating
from the machining steps of bolt production
accumulated in the automatic electroplating
line's cleaning tanks. An  inoperative filter
system on the electroplating tanks also
needed repairs. Once the repairs are made
on both lines, it should be possible to deter-
mine whether the systems are adequate to
maintain contaminants at low levels;.
Installing a new filtering system was recom-
mended.
   Anode bags were recommended to keep
contaminants and dirt from the zinc balls
out of the electroplating solution. Addition-
ally, a drain board was needed over the dri p
tank following the chromate rinse on the
automatic line to direct dragout back to the
rinse tank. By changing to a trivalent-
chrome-conversion coating process instead
of the hexavalent chrome  process, the facil-
ity should decrease the toxicity of the waste
it produces. This would save on treatment
costs, because hexavalent chrome  must  be
reduced chemically to its trivalent form  
which is less toxic and less expensive to treat
 before it is sent to a treatment plant.
   Some potential disadvantages of these
changes are a slight reduction in corrosion
protection, the necessity of closer process
monitoring and testing, and the fact that triva-
lent chrome coats are available only in bright
blue instead of the customary light yellow.
   Use of still rinse tanks following elec-
troplating and chromating was  recom-
mended to recapture some of die chemical
dragout from these processes. This
method  should recapture about half of the
chemical lost to dragout. It was also rec-
ommended that air agitation be used in the
tanks to increase rinsing efficiency.
   The water supplied to  the electroplating
process should be as clean as possible. It was
recommended that the facility's reverse
osmosis purification unit  be used to supply
water to the electroplating, chromating and
still rinse tanks. This would remove poten -

-------
tial contaminants in tap water, including
total dissolved solids and hardness, before
its use in the electroplating line, increasing
process efficiency.
   The barrel withdrawal rates were mea-
sured at 5.2 meters per minute in the auto-
mated line and 8.2 meters per minute in the
manual line. The maximum withdrawal rate
should be about 2.4 meters  per minute.
Changing this would decrease die amount
of dragout from each tank,  resulting in
decreased chemical use.
   It was also recommended that the hang
time of barrels over the tanks  be increased
by pausing longer before moving to the next
station. Although hang time on the auto-
mated line was 23 seconds, significant drip-
ping from barrels occurred after this time.
Hang time over tanks on the manual line
varied. Generally, hang time was observed
to be minimal, and dragout was significant.
   Results of system changes. Several
recommended changes to the automatic
electroplating line were implemented. All
tanks were cleaned, inside and outside, on
the plating line, and accumulated bottom
sludge was removed. The bath contents of
the electroplating tank were pumped into
a temporary holding tank, and nonhaz-
ardous bottom sludge was shoveled into
eight 55-gallon drums for disposal. The liq-
uid portion of me plating bath  was pumped
back into the plating tank, and additional
chemicals and water were added to restore
them to normal levels.
   Other changes included:
    Regular testing of cleaning, acid dip,
electroplating and chromating processes to
maintain optimal-level chemical concen-
trations;
    Hiring a qualified individual to per-
form operational control  testing and work
with the plating operator to make required
chemical additions; and
    Reducing rinse flows, and installing
flow measurement and  countercurrent
rinsing.
   Flow control devices have been installed
on the rinses following the alkaline clean-
ing and acid-dip processes to maintain flow
rates at recommended levels. The two sys-
tems have not been connected as recom-
mended. Flow rates for the two rinses
following electroplating also have been
reduced* The new rates have not been mea-
sured, so it has not been determined
whether diey are being maintained consis-
tently. The plating operator reports the
valves that control flow are not opened as
far as in the past. Besides decreasing the rin-
sewater flow rate, adding the countercur-
rent system to the manual line should
increase the rinsewater's utility.
   Product quality has been increased sig-
nificantly, as evidenced  by results of the 5
percent neutral salt spray testing performed
on bolts plated on the automated line before
and after die changes occurred. The results
      Tank clearing, sludge
      removal and use of oi
      absorbent pads on the
      cleaning baths should
      reduce the dragout of
      dft, grease and other
      contaminants to down-
      stream processes.
show a 1,000 percent increase in white rust
protection and a 550 percent increase in red
rust protection.
   From a waste prevention and minimiza-
tion  perspective, the changes have been
effective. Reduction in rinse flows should
lead to less wastewater for treatment at an
onsite facility. Tank cleaning, sludge removal
and use of oil absorbent pads on the clean-
ing baths should reduce the dragout of dirt,
grease  and other contaminants to down-
stream processes. This will increase bath life,
resulting in fewer bath dumps and reduced
chemical use. Costs of implementing these
changes have been modest.
   The galvanizing system. The facili-
ty's galvanizing process consists of pickling,
rinsing, prefluxing, galvanizing and final
rinsing. The pickling step prepares work
for galvanizing by removing oxides from
 the steel surface using a 10 percent sulfuric
 acid solution at 70 degrees Celsius.
   Work pieces are rinsed after pickling.
 The preferred method is to dip them in the
 rinse tank, which is filled with unheated
 municipal water. The rinsewater is agitated
 by moving the pieces back and forth in die
 tank. After the  first rinsing, work pieces are
 placed in the preflux tank, a crucial step in
 the dry-kettle galvanizing process. Work is
 coated with flux chemicals before entering
 the zinc kettle. The preflux tank is main-
 tained at 70 degrees Celsius.  The preflux
 solution generally is allowed  to dry thor-
 oughly before galvanizing.
   Galvanizing is accomplished by immers-
 ing steel in a tank rilled with molten zinc for
 two to three minutes. Most steel galvanized
 at this plant uses the wet-kettle method. A
 flux layer is floated on top of the galvanizing
 kettle, and work pieces pass through it as they
 enter and leave the kettle. For galvanizing
 materials, such  as building components, the
 kettle flux layer is skimmed to the side and
 not used. Work pieces are cooled by rinsing
 them in a second rinse booth next to the gal-
 vanizing kettle. This final rinse is needed to
 cool the work to below 200 degrees Celsius,
 which prevents growth of a brittle ;dnc-steel
 alloy layer. Cooling also allows operators to
 handle the pieces.
   Galvanizing operations. Pollution
 prevention efforts in galvanizing were con-
 centrated on reducing the volume imd metal
 content of rinsewater, as this is the princi-
 pal medium through which metal is  lost.
 Volume reductions can be accomplished by
 installing additional galvanizing equipment.
 Metal content reductions are possible by
 discontinuing use of the kettle flux or
 switching to a different kettle flax.
   The galvanizing system initially used
 about 265 cubic meters of rinsewater per
 day. Flow through the first rinse booth was
 measured during wastestream assessment
 at 1,200 liters per minute. Freshly galva-
 nized pieces are cooled in the second rinse
 booth. Flow through this booth was esti-
 mated at about  1,200 liters per minute. The
 rinse booths operate only while materials
 to be rinsed are carried through diem.
   Rinsing in a tank instead of a booth is
die most important step in decreasing gal-
vanizing water use. Using rinse tanks after
pickling also is important. It was recom-

-------
mended that rinse booths be replaced by
rinse tanks linked in a countercurrent flow
arrangement. This allows water to be reused
several times before being discharged and
ensures that work pieces are rinsed with clean
water as they leave the process line.
   A rinse test conducted to verity' die use-
fulness of the rinse tank concept successfully
demonstrated the feasibility of continuous-
flow rinsing. Based on die results, a contin-
uous rinsewater flow rate ot 24 liters per
minute removes pickling acid adequately for
two rinse tanks in series.  This flow rate cools
the work, preventing the water temperature
from rising  high enough to pose a safety
problem. The proposed system would use
no more than 3 5 cubic meters of water per
day, representing a savings ot about 83 per-
cent. As a result of the study, water-saving
(low-flow) nozzles were  installed in the rinse
booths. This immediately reduced water use
by 60 percent, yielding water and waste treat-
ment savings of about $250 per day.
   The proposed galvanizing equipment
changes cost about $70,000. Ventilation sys-
tem improvements to remove pickling solu-
tion vapors from the proposed pickling tank
location would cost $25,000. Due to the
expense, phased  installation of suggested gal-
vanizing changes was recommended. The
payback period is estimated at about 10
months.
   Livestock fencing is being fluxed twice
 once in the preflux tank and again as it
enters the kettle. For galvanizing objects
other than fence panels, kettle flux is not
used. The kettle flux is 98 percent zinc chlo-
ride and contains a small amount of potas-
sium chloride. Kettle flux adds significandy
to the metal content of galvanizing rinse-
water, so that discontinuing its use would aid
pollution prevention.
   Prerluxing is crucial in dry-ketde galva-
nizing. To obtain good  fluxing, proper con-
centrations of zinc chloride and ammonium
chloride must be maintained, and iron and
sulfate concentrations minimized. Frequent
sampling is required.
   Switching from zinc  chloride preflux to a
mixture of mosdy ammonium chloride and
some zinc chloride or ammonium chloride
alone was recommended. This probably would
enhance product quality,  because the proposed
countercurrent flow system (with fresh water
being added at the final rinse tank) would not
complicate preflux chemistry.
   Another problem with the galvanizing
operation was a layer of oil floating on the
surface of the acid bath. The oil could be
minimized by iastalling a skimmer to remove
it periodically or to reduce oil use in the fab-
ricating step.
   The painting system. The  painting
operation at the facility consists ot  washing,
etching,  oven drying, spray painting and
oven curing. The plant's painting operation
in 1992 was estimated to have emitted about
37,500 kilograms of xylene and 11,000 kilo-
grams of toluene. Reducing emissions of
these volatile organic compounds should be
        was to switch to an
        process to reduce
        VOC emissions and
        eliminate chromic-
a top priority.
   Two types of paint are used at the plant.
A solvent-based paint is used for painting
gates, and a silicone polyester paint is used
for coating building panels. Seventy-four per-
cent of die paint used in the automatic paint
line in 1992 was used to paint farm gates.
About 2,200 liters per month of a mixture of
aromatic solvents are used for such purposes
as cleaning paint-supply piping.
   The only practical way to reduce VOC
emissions significantly is to change paint
materials. One alternative is to use water-
based paint for the gates. If water-based
paints are applied electrostatically, a high
transfer efficiency  can be obtained. The
investment should be relatively small,
because the only facility change required is
installing new spray equipment. Immediate
testing of water-based paints was recom-
mended.
   Another suggestion was to switch to an
autophoretic painting process to reduce
VOC emissions and eliminate chromic-acid
etching. This involves dipping metal to be
painted into tanks filled with paint The coat-
ing is deposited via a chemical reaction
between the paint and metal which requires
several minutes of immersion. The auto-
phoretic process resembles electrocoating
but requires no electric current. Metal
painted using this process reportedly has
withstood salt spray tests up to 3,000 hours
without coating failure. The paint report-
edly exhibits a high degree of hardness and
good resistance to chalking from ultraviolet
light exposure.
   The estimated cost of an autophoretic sys-
tem to coat gates was $300,000. A serious
drawback of diis method is that color varies
with the dissolved iron concentration in die
paint, which increases slowly due to contact
ot the paint with the steel being painted.
Another drawback is the tact that a separate
paint tank is needed for each color.
   Another alternative is powder coating.
Agricultural gates are ideally suited for pow-
der coating, because they are made in only
two colors. Transfer efficiency is not an issue,
because overspray is captured and blended
with fresh powder for reuse,  and VOCs are
not emitted. An industrial supply contractor
estimated  that powder coating could be
added to the existing paint line for about
$40,000. However, installation costs prob-
ably would  be higher, because the automatic
paint line is old and should be replaced. A
new paint line was estimated to cost about
$200,000.
   Pollution prevention in die painting area
at this plant will not be offset by significant
savings in disposal costs.However, the Cleim
Air Act will require that action be taken soon.
As a result ot this study, the plant has exper-
imented with water-based paints and
requested bids to construct a powder coat-
ing system.
   Tubing manufacture system. A tube
mill at the facility forms metal pipe from
coils of sheet steel. The plant makes tubing
for all its gates and also sells tubing to other
companies. The major tube mill compo-
nents include a coil unwinder, feeder, ini-
tial cold rolls, welder, re-galvanizer, final
cold rolls, metering cutter and coolant dis-
tribution system. A water-based fluid ax)lant
is used to lubricate and cool the tube mill.

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   About 800 liters of coolant per month are
consumed at a cost of" about $800. The
coolant flows from application points into
sumps below the components. The sumps
drain by gravity to a large collection tank,
which contains an oil removal system con-
sisting of a plastic tube pulled through the liq-
uid coolant. Floating oil adheres to the
polyethylene tube and is removed by a scraper.
However, the oil removal system is unable to
remove oil quickly enough.
   Oil in the coolant originates from grease
leaking out of the tube mill gearboxes. Over
the years, oil and grease leaks have covered
the tube mill and the surrounding area.
Grease combines with metal filings created
when excess metal is scraped from fresh
welds. Together, the grease and filings form
a black substance that fills the bottom of the
sumps in about a month. The mill occa-
sionally is shut down while operators scoop
out the grease. About two-thirds of the
coolant is lost  each time the sumps are
cleaned, and this is the only time coolant is
discharged from the system.
   Recommendations for the tube mill focus
on minimizing grease contamination of the
coolant. The old oil-removal system should
be replaced with a system  that would allow
coolant reuse. A suitable unit was estimated
to cost less than S2,500. The payback period
was estimated at less than six months, assum-
ing the coolant's usable life is doubled. If
coolant could be used longer, the payback
period would be shorter.
   The coolant also turns rancid. Coolant
rancidity usually is controlled by adding a bio-
cide. If rancidity problems  continue after an
improved oil removal system is installed, a dif-
ferent biocide may be needed. Gearbox leak-
age should be prevented or kept from falling
into the sumps through regular maintenance.
 In addition, preventing metal filings from
 falling into the sump below the weld scraper
 would keep them from combining with the
 grease. It was recommend that the entire area
 be shut down for thorough cleaning, as this
 would vastly improve system operation.
 Cleaning should include equipment, floor
 grates and the return trough.           ^]

   M.F. Dahab is an associate professor of civil
 engineering and biological systems engineering
 at the University of Nebraska-Lincoln. Jim Limd
 is director of the Industrial Pollution Prevention
 Project in the Environmental Protection Agen-
 cy's Office of Water.
   The project on vchich this report is based iras
funded jointly by  EPA and the University of
 Nebraska-Lincoln Center for Infrastructure
 Research.

 More reading
   Anonymous, "Steelcase Inc. replaces zinc
 plating lines," Finishers Management, March
 1992, pp. 17-20.
   Cook, T.H., D.E. Mergen and D.L.
 Clark, "Increasing profits in hot dip galva-
 nizing," .MetalFinishing, Vol. 84, No. 23,
 1986, pp. 23-27.
   Cook, T.H. and W.S. Horton, "Ammo-
 nium chloride control in galvanizing pre-
 flux," Metal Finishing, Vol. 80, No. 19, 1982,
 pp. 19-23.
   Dahab, M.F. and D. Montag, "Waste
 minimization in a metal-finishing industry:
 A pilot project,"  Third International Confer-
 ence on Waste \Ianagement in the Chemical and
 Petrochemical Industries, Salvador-Bahia, Brazil,
 Oct. 20-23, 1993.
   Dahab, ME, D. Montag and J. Parr, "Pol-
 lution prevention and waste minimization at
 a galvanizing and electroplating facility," Water
 Science and Technology, in press, 1994.
   Durney, L.J., Electroplating Engineering
Handbook. Chelsea, Mich.: Lewis Publishers
Inc., 1984.
   Hunt, G.E., "Waste reduction in the
metal finishing industry," Journal of the Air
Pollution Control Association, Vol. 38, No. 5,
1988, pp. 672-680.
   Montag, D., Pollution Prevention in the
Metal Finishing Industry (master's thesis). Lin-
coln, Neb.:  University of Nebraska-Lincoln
Libraries, December 1993.
   Sjoukes, F., "Chemical reactions in fluxes
for hot dip galvanizing," Anti-Corrosion Meth-
ods and Materials, Vol. 37, No. 4, 1990, pp.
12-14.
   Parr,J.,  Waste Minimization Opportuni-
ties for the electroplating industry: A Case Study
(M.S. thesis).  Lincoln, Neb.: University of
Nebraska-Lincoln Libraries, February 1994.
   Tsai, E.C. and R. Nixon, "Simple tech-
niques for source reduction of wastes from
metal plating operations," Hazardous Waste
& Hazardous Materials, Vol. 6, No. 1, 1989,
pp. 67-78.
   U.S. Environmental Protection Agency,
Guides to Pollution Prevention-The Fabricated
Metal Products Industry. Washington, D.C.,
EPA Report No. EPA/625/7-90/006, July
1990.
   	Facility Pollution Prevention Guide.
Washington, D.C., EPA  Report  No.
EPA/600/R-92/088, May 1992.
   	.-I Primer for Financial Analysis of
Pollution Prevention  Projects. Washington,
D.C., EPA Report No. EPA/600/R-93/059,
April  1993.
   University of Tennessee Center for
Industrial Services. Waste. Reduction Assess-
ment and Technology  Transfer, 2nd edition,
9/22-9.
   Wentz, CA Hazardous Waste blanagement
New York: McGraw-Hill Book Go., 1989.
                         Reprinted from ENVIRONMENTAL SOLUTIONS, November 1994
                                     AN ADVANSTAR     PUBLICATION  Printed in U.S.A.

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            INDUSTRIAL POLLUTION PREVENTION PILOT PROJECT

                                  A Summary Report
Introduction

       This project is intended to develop an industrial pollution prevention and minimization
pilot project  in  Nebraska.   The  goal  of the project  is to demonstrate that  through  proper
management and operating practices, the total pollution produced by an industrial operation can
effectively be reduced significantly. The net effect of this pollution prevention program is to
improve the economic net-worth of the industry by lowering expenditures on pollution  control
measures as well as minimizing the burden of regulation imposed by the government.  Behlen
Manufacturing Company of Columbus, Nebraska, has agreed  to be the  demonstration site for
this project.

       Behlen Manufacturing is an employee-owned facility engaged largely in the production
of fabricated metal products for farm and industrial uses.  The facility is located in Columbus,
NE in  a predominantly rural area.  The plant site is a 97 acre  area on which several buildings
are located. The largest of these buildings is a 805,000 square foot manufacturing facility and
a 42,000 square foot office complex.   Because of the nature  of its manufacturing, Behlen is
permitted  under the RCRA and  the NPDES systems.

       In  its various  manufacturing processes, Behlen performs  many operations  including
electroplating, conversion coating, cleaning, machining, grinding, impact  deformation, shearing,
welding, sand blasting, hot-dip coating, painting, assembly and testing.  Many of these processes
result in the production of a variety of pollutants (gaseous, solid, and liquid) that have to be
disposed of in some fashion depending on their nature. For example, the hot-dip galvanizing
process results in the production of rinse water which must be  treated as a hazardous substance
containing heavy metals (e.g. zinc and  iron) in addition to being highly corrosive.  The painting
processes  result in the production of used  industrial  cleaners,  acids, hexavalent chromium,
solvents, and chemicals used in the cleaning  and de-greasing of metal components.

       All process wastewaters produced at this facility are treated in accordance to stipulations
under the NPDES permit.  The wastewater  is treated by  lime and polymer addition and pH
adjustment before discharge to the Loup Power Canal. In the past, waste disposal at this facility
resulted in potential problems to both surface  and ground water  resources  in the area.  The waste
disposal systems at Behlen undoubtedly  constitute a  major  expense  to this facility.  The
management  at Behlen welcomes any improvement  in its economic picture  by reducing its
pollution control expenses and lowering or eliminating the burden of regulation the company
must endure.

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Project Tasks

       In developing the demonstration pilot project at Behlen, emphasis was placed on areas
where the impact on reducing the total pollutant load produced by this facility was greatest.
These areas are electroplating, hot-dip galvanizing, the painting line, and the tube-mill area.  As
pointed out above, these areas produce the bulk of the wastes with the greatest toxicity and
hazard, and consequently any improvements in these areas should result in the greatest impacts.
In developing a work plan,  a multi-media approach was emphasized in developing pollution
prevention and minimization strategies affecting all operations and processes  at Behlen.  The
work plan consisted of several tasks. These tasks are summarized as follows:

  1.    A detailed assessment and evaluation of the current practices in the areas identified above
       along with a detailed characterization of all wastes (gaseous, liquid, and solid) produced
       at this facility.

  2.    Identification  and  delineation of  all possible  pollution prevention  and minimization
       opportunities.

  3.    Economic and technical evaluation of all  waste prevention and minimization alternatives
       including short as well as long term impacts  of these alternatives.

  4.    Recommendation to  Behlen Manufacturing  for implementation  based  on economic
       priority in  terms of greatest benefit and shortest pay-back periods.

  5.    Providing  technical  assistance, where appropriate,  to Behlen  during  the  process of
       implementation of the recommended alternatives.

  6.    Review of the results and impacts on waste prevention after the implementation of the
       alternatives.

  7.    Development of a demonstration program involving technical workshops, if appropriate,
       and informational materials such as capsule and summary  reports  for use by interested
       individuals and corporations.

  8.    Reporting  of  the study results to  the U.S.  EPA in  generic terms for use by other
       industries  with similar processes and operations.
       This report provides a summary of all activities completed to date and essentially covers
Tasks 1 through 4, as identified above. A detailed summary report will be provided to Behlen
Manufacturing at the conclusion of this study.

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Project Recommendations
       The initial phases of this study were begun in early 1992 with a detailed waste stream
assessment  of all operations at Behlen Manufacturing.  In this report, the recommendations
presented to Behlen for consideration are discussed sequentially by process category, as indicated
above.
Galvanizing

       The galvanizing process at Behlen is a five step process consisting of pickling, rinsing,
prefluxing, galvanizing, and final rinsing.  Pollution prevention efforts in the galvanizing area
should concentrate on reducing the volume and metal content of rinse water since this is  the
principal medium through which metal  is lost.  Volume reductions can be accomplished by
installing additional galvanizing  equipment.   Metal content reductions are possible by either
discontinuing use of the kettle  flux, or switching to a different kettle flux.
Rinse Water Use

       The galvanizer uses about 55,000 gallons of rinse water per day.  The rinse booth located
between the acid tank and the rinse tank is used for spray rinsing after pickling. Flow through
the booth was measured during the waste stream assessment period at 300 gallons per minute.
Freshly galvanized pieces are cooled in the booth next to the galvanizing kettle. Flow through
this booth these days is estimated at approximately  300 gallons per  minute.   The flow  rate
estimate for the second rinse booth has been reduced to reflect  recent modifications after the
assessment was completed.

       Rinsing in  a rinse tank (instead of a rinse booth) after galvanizing is the most important
step in decreasing galvanizing water use.  Use  of rinse  tanks after pickling is also important.
As discussed at the March 19th meeting at Behlen, the rinse booths could be replaced by rinse
tanks linked in a counter-current flow arrangement as shown in Figure 1.  The benefit of such
a system  is  that it allows water to be reused several times before it goes down the drain,  in
addition to the fact that work pieces are always rinsed using the cleanest water as they leave the
process line.

       A  rinse  test was conducted on April 1,  1993  which successfully demonstrated the
feasibility of continuous-flow rinsing.  Based on the results of the rinse test, a continuous rinse
water flow rate of 7 gallons per minute will remove pickling acid adequately for two rinse tanks
in series.  A flow rate of 7 gpm flow will cool the work, preventing the water temperature from
rising high enough as to pose a worker safety problem.

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       The proposed system would use about 10,000 gallons per day. This represents a savings
of about 45,000 gallons of water per day.  The cost of these proposed galvanizing  equipment
changes is estimated at  about  $70,000,  and ventilation system  improvements required to
remove pickling solution vapors from the proposed pickling tank location would cost $25,000.
Due to the expense of the  suggested galvanizing changes, phased  installation is recommended.
The final cooling tank could be added first and linked to the existing system as shown in Figure
2.; entitled Interim Solution.  For a cost of about $17,000, the rinse tank at the West end of
the line could be installed in a pit on the East end where the second rinse booth is now located.
The costs and  payback  periods  for  the recommended galvanizing system  and  for  the
recommended  interim solution are summarized in Table 1.
Table 1.  Costs and pay-back periods for the recommended changes to the galvanizing line.
OPTION
Adding 3 rinse tanks as in
Figure 1 - Proposed System
Using the existing rinse
tank in place of the second
rinse booth as in Fig. 2
COST
$95,000
$17,000
PAYBACK
10 months
3 months
Galvanizing Chemistry

       Fencing currently is being fluxed twice: once in the preflux tank, and a second time as
it enters the kettle.  For galvanizing of objects other than fence panels (such as building parts),
the kettle flux is skimmed to the side and is not used.   The kettle flux is called Preact, and is
supplied by Mineral Research Corporation.  Preact is 98% zinc chloride, and contains a small
amount of potassium chloride.  Behlen uses 16,300 pounds of Preact each month, at a cost of
about $8,500. Kettle flux adds significantly to the metal content of galvanizing rinse water, so
discontinuing the use of kettle flux would enhance pollution prevention.

       Prefluxing is crucial in dry kettle galvanizing.  The preflux tank holds a solution of zinc
chloride  (ZnCl2)  and  ammonium chloride  (NH4C1).   To  obtain  good  fluxing,  proper
concentrations of ZnCl2 and NH4C1 must be  maintained, and iron and sulfate concentrations
must be minimized.  Frequent sampling is required.

       Two preflux chemistry terms which may be unfamiliar are degrees Baume (Be), and
Ammonium Chloride Number (ACN).   The Be is a unit of density.  Preflux density is directly
related to the ZnCl2 concentration.  Optimum density ranges from 12 to 15  Be (1.09 g/ml to
1.12 g/ml)  as measured at  70  to  75F. The ACN of a preflux  is the ratio of the  NH4C1
concentration divided by the concentration of all other components in the solution.  Opinions

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about the best ACN differ. For example, Mineral Research Corporation recommends 1.17 while
Dr. T.H. Cook (America's most prominent galvanizing researcher) recommends 1.4 to 1.8, and
F. Sjoukes (European galvanizing expert) recommends 1.75 to 2.5. Every three or four months,
Mr.  Dick Robak (of Behlen) sends a preflux sample to Mineral Research  Development Corp.
of Charlotte, N.C.  Mineral Research  performs a detailed analysis, including ACN.  More
frequent ACN determinations (about every 2 weeks) would be helpful in attempting to galvanize
strictly by the "dry kettle" method.

       If the kettle flux continues  to  be used after  installing a counter  flow rinse system,
frequent preflux sampling will be needed in order to maintain a proper ACN.  This is because
zinc chloride will be dragged into the preflux from the post-pickling rinse. The magnitude of
zinc chloride drag-in will be established when samples taken at Behlen during a June 16th rinse
test  are fully analyzed.   Tony Raimondo  Jr.  (of Behlen) indicated  that Mineral  Research
Development would probably be willing to analyze samples more frequently, and that they would
still  provide  the service for free.  Also,  in-house preflux  testing is possible.  In his article:
"Ammonium Chloride Control in Galvanizing Preflux," Cook (1982), Dr. T.H. Cook described
a procedure for determining ammonium chloride concentration.  The procedure is relatively
simple, but  it utilizes strong a strong acid and  a strong base,  and  therefore,  an experienced
chemist should perform the test.  It should be possible for  either Mr. Will or Mr. Zobel (of
Behlen)  to conduct such a test.

       In addition,  if a kettle flux must be maintained, it would be helpful to switch to one that
is a mixture of zinc chloride and ammonium chloride, or even to pure ammonium chloride.  Use
of pure ammonium chloride  kettle  flux  is  described by  F.  Sjoukes in an  article  entitled:
"Chemical Reactions in Fluxes for Hot Dip Galvanizing" (Sjoukes, 1990).  A different kettle
flux would probably give better results,  and with different flux, the proposed counter  flow
system  with  fresh  water  being added to the final rinse tank  would  not complicate preflux
chemistry.

       Another problem associated  the galvanizing operation is the  oil floating on the surface
of the acid bath. This is not surprising since there is no caustic cleaning stage prior to pickling.
The oil problem could  be minimized by installing a trough into which oil can  be  skimmed
periodically.  An attempt should be made to minimize oil on steel to be galvanized.
Painting

       Painting  is a sequential  process  consisting of washing, etching,  oven drying, spray
painting, and oven curing. The paints used at Behlen are of the traditional solvent based variety,
and contain volatile organic compounds (VOC's). Last year the painting operation was estimated
to have emitted about 82,000 pounds of xylene, and 23,000 pounds  of toluene.  Xylene and
toluene are defined as hazardous by the 1990 Clean Air Act, and will be regulated strictly in the
near future, so reducing emissions of these VOC's should receive a high priority.

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       The two major types of paint in use at Behlen are Farmmaster paint, which is used for
painting gates,  and Pratt and  Lambert silicone  polyester paint,  which is used for painting
building panels.  Last year (1992), 34,567 of the 47,312 gallons of paint consumed by the
automatic paint line were used  in painting gates.  Additionally, large quantities of a solvent
named "Vanblend 99" are used.  This is a mixture of several aromatic solvents, and is used with
Farmmaster paint for such purposes as line  cleaning between colors.  Approximately, 570
gallons of Vanblend 99 are consumed each month.
Painting Alternatives

       The  only practical way to significantly  reduce VOC emissions is to change paint
materials.  There are several possible materials from which to choose.

       One choice is to use water based  paint for gates,  which accounts for over 70%  of
Behlen's paint use. If water based paints are applied electrostatically, a high transfer efficiency
can be obtained.   New spraying equipment is all  that would be required to  make this change,
and therefore, the investment should be minimal.  George Werner has reservations about water
based spray painting systems,  so there are  no plans to test such equipment.

       With regard to painting, it is necessary that everyone concerned be kept aware of the
importance of making progress toward reducing VOC emissions.  Something really needs to be
done about VOC's, and since using water based paint is the lowest cost solution, testing of water
based painting alternatives should be conducted.

       Another way to reduce VOC emissions from painting gates;  and possibly to eliminate
chromic acid etching of galvanized building panels; is to switch to an autophoretic painting
process; an example of  which is  manufactured by Parker  Amchem.   This process  involves
dipping metal to be painted into tanks filled  with paint.  Immersion is required because the
coating is deposited by a chemical reaction  between the paint and the  metal which takes several
minutes to occur.  The autophoretic process resembles  electrocoating, except that  no electric
current is required.  Metal painted by  this  process reportedly has withstood salt spray tests of
up to 3,000 hours without coating failure.  The paint exhibits a high degree of hardness, and
good resistance to chalking from ultraviolet  light exposure.  An autophoretic system to coat gates
would cost about $300,000.  Parker Amchem has never built an autophoretic  coating system
large enough to coat building panels, so detailed analysis would be required  to ensure that it is
possible.  Another difficulty is that the red and green vary somewhat in color.   The variation
is due to  the changing iron content of the paint as corrosion  products  enter the paint  and as
makeup chemicals are added.   Since each  color requires a separate tank, and building  panels
come in several colors, the only color which would be practical for building  panels probably is
a clear coating which could be used as a base coat for pigmented paints.  Since an autophoretic
coating is a good primer, the top coat can be an inexpensive paint.  Companies using this system
have reported the cost of applying autophoretic paint to be about 3 cents per square foot.  Parker

                                            8

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 Amchem is willing to assist Behlen in planning an autophoretic coating system.

       Agricultural gates are ideally suited to powder coating because they come in only two
 colors. Transfer efficiency is not an issue in powder coating because overspray is captured and
 blended with fresh powder for reuse.  Powder coating  gates would eliminate VOC's from about
 70% of the current production.  Industrial Finishing Systems, which is one of Behlen's long-time
 painting equipment suppliers, indicated that powder coating could be added to the existing  paint
 line for as little as $40,000. Unfortunately, the real cost of a powder coating system would be
 much higher.   This is because  the automatic paint line is quite old, so powder coating should
 be installed on a new line.  A new line would cost about $200,000.  The pollution prevention
 measures in the painting area probably will not pay for themselves in terms of  reduced current
 waste disposal costs,  but Clean Air Act requirements will  soon mandate that action be taken.
 Estimates of the installation costs for various painting alternatives are  shown in Table 2.
Table 2. Estimated costs of painting alternatives.
OPTION
Water Based Spray Painting
Autophoretic Coating
Powder coating
COST
$25,000a
$300,000
$200,000
 Approximate; industrial rimsning Systems is preparing a detailed estimate.
Tubing Manufacture

       A water-based fluid coolant (Metkool 711) is used by Behlen for lubrication and cooling
of the tube mill.  About 195 gallons per month are consumed at a cost of about $800.  The
coolant flows from  its application points into sumps below the components, and the sumps, in
turn,  drain by gravity to a large collection tank.  The collection tank contains an oil removal
system, consisting of a plastic (tygon) tube  pulled through the liquid coolant.   Floating oil
adheres to the polyethylene tube, and is removed by a scraper.  The oil removal system is not
able to remove oil fast enough.

       The oil in the coolant comes from grease leaking out of the gearboxes.  In addition, oil
and grease cover the  tube mill and the surrounding area.  Grease  and metal filings from the;
scarfer combine to make a black substance that fills the bottom of the sumps in about a month.
The mill is occasionally shut down while operators scoop out all the grease.  About two-thirds;
of the coolant is  lost each time the sumps are cleaned, and this is the only  time  coolant is
discharged  from the system.

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Recommended Tube Mill Changes

       Recommendations for the tube mill are mostly concerned  with  changes which would
minimize grease contamination of the coolant:

       The old oil removal system needs to be replaced.  A suitable oil removal system can be
furnished by Production Supplies Inc. An efficient oil removal system should allow the coolant
to be used for several times its current life.  The new oil removal unit only costs $2,500.
Doubling the coolant's useable life would pay for a new oil removal system  in  6 months.
Beyond that, the actual pay-off period could be even shorter.

       There is a  problem with the coolant  turning rancid.   Coolant rancidity  is usually
controlled by adding one of several possible  biocides.  If rancidity problems continue after an
improved oil removal system is installed, a new biocide may be needed.

       It should be possible to prevent gearbox leakage, or at least reduce leakage from falling
into the sumps through regular maintenance.  Also, preventing metal filings from falling into the
sump below the scraper which removes excess metal from the fresh weld, and thus keep them
from  combining with the grease.

       We strongly recommend shutting down the entire area for a short period of time for a
thorough cleaning.  This would vastly the improve operation of the system.  The cleaning should
include all equipment, floor grates, and the return trough.
 Automated and Manual Electroplating

       Behlen Manufacturing currently operates both an automated and a manual electroplating
line.  The processes are shown in Figures 3 and 4. These lines are used to deposit (electroplate)
a thin zinc film onto small items such as  nuts and bolts, which are then used in the construction
of larger plant products such as farm buildings.

       The automated electroplating line  processes an average of 140 pounds of work per barrel.
There are 36 stations on the line, with an approximate cycle time of 3.5 minutes at each station
(about two hours per barrel). The work is first cleaned in a soak cleaner and an electrocleaning
solution.  It is then rinsed, pickled in a  hydrochloric acid bath, and rinsed again before going
into a chloride-zinc electroplating bath.  After being in the plating bath for about an hour and
ten minutes (20 stations),  the work is rinsed. A light yellow chromate finish is added.  A short
rinse (20 seconds)  follows the chromating process after which the work is  dried at 150 F.

       The manual process  is more operator intensive, which requires hand moving of barrels
from station to station. The barrels are  bigger but the average load of work per barrel is still
 140 pounds.  This line is  used more often than the automated line,  especially  when  small
quantities need to be plated. The work  is cleaned in a soak cleaning bath  (no electrocleaning)

                                            10

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 for about 15 minutes.  It is then rinsed, pickled in hydrochloric acid, and rinsed again before
 being placed in the chloride-zinc electroplating tank (stainless steel pieces are dipped in nitric
 acid, instead of hydrochloric acid -- this does not occur  often).   The work is plated for an
 average of 1 to 1.5 hours before being removed from the tank.   A short rinse precedes the
 chromate coating; which can be clear or yellow, depending on customer preference.  After a
 final short rinse the pieces are placed  on a table to air dry.
Recommended Changes to the Electroplating Process:

       Rinse rates should be reduced to decrease the amount of wastewater being discharged to
the treatment plant.  We believe that the rinse flow rate after the cleaning and acid dip processes
on both, the automated and manual  electroplating  lines, can be reduced to as  low as 2 gallons
per minute (gpm). This value needs to be confirmed by actual rinse testing (as should the other
rinse changes recommended).  The  effluent from  rinsing after the acid dip should be directed
to the rinse tanks after the cleaning process.  This change would save a total of about  19,000
gallons  of water per  day resulting  in a cost savings of about $150.00 per day  for  waste
treatment,  sludge  disposal, and water costs.   Counter-current  tanks similar to those  on the
automated line (after the cleaning and acid dip processes) will be needed on the manual line to
incorporate this change.  The cost of these counter-current tanks is estimated at $1,000.00. The
estimated cost of flow control nozzles to maintain the 2 gpm flow rate  is about $45.00.  A
summary of costs associated  with changes in the electroplating line are shown in Table 3.

       The rinse process  after the electroplating tank on both the automatic and manual lines
should be changed to counter-current with a rinse flow of 5 gpm. About 6000 gallons of water
per day can be saved resulting in a cost reduction of $50.00 per day. The  costs associated with
these changes  are estimated at $1,000 for the counter-current tanks system and $45 for the flow
control nozzle.

       To obtain better product quality and assure that the lower flow rates will not compromise
rinsing efficiency it  is  recommended that housekeeping practices be changed.  There needs to
be a thorough clean-up of the electroplating area including the tanks (inside and out), floor, and
all equipment related  to the electroplating process.  Records should  be kept to show  when
maintenance is done, tanks are emptied, chemicals  are added, and testing on tank parameters is
done (e.g. pH, temperature, chemical concentration).  The testing of tank parameters should be
done on a daily basis  for such variables as  temperature and concentration of  the cleaners,
concentration  of the acid dips, zinc metal, boric acid, total  chlorides,  pH,  and the wetting
solution in the electroplating tanks as well as pH, temperature, and concentration of the chromate
in the chromating tanks.
                                           11

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       Other recommended housekeeping changes  needed to improve the process  include
increasing the temperature of the cleaning tanks on the automatic line from 160F to 180F.
Grease skimming from the top of the cleaning tanks  must be improved to remove more of the
grease and oil before it carries over into the downstream processes. The filtering system on the
electroplating tanks needs to be repaired or improved.  Once the current  filtering system  is
repaired  (on both lines), it will be possible to determine if this system is enough to maintain
contaminants at proper levels.  It is recommended that a new filtering system be installed if this
is not the case.  Anode bags should be used to keep contaminants and dirt in the titanium baskets
(used to  hold zinc balls) and out of the electroplating solution.  Also, a drain board should be
installed  over the drip tank after the chromate rinse (on the auto line) to direct all dragout back
into the rinse tank.

       By using a trivalent chrome conversion coat  process instead  of the current hexavalent
chrome process, Behlen could reduce the toxicity of a hazardous  waste, lower  treatment costs
(hexavalent  chrome must be chemically reduced to trivalent before sending it to waste treatment
plant), and maintain overall costs at current levels.   The disadvantages of these change would
be a  reduction in corrosion protection, the operator must monitor the process closely, and
trivalent  chrome coats are only available in a "bright blue" color.

       To recapture some of the chemical dragout from the electroplating and chromating, it is
recommended that still rinse tanks  be used after these processes.  It is estimated  that about 50%
of the chemical lost to dragout can be recaptured by  this method.  It is also recommended that
air agitation be used in  the tanks to increase rinsing efficiency.

       Since Behlen has a reverse  osmosis (RO) purification unit which is currently not in use,
it is recommended that RO water be used to supply water to the electroplating, chromating, and
still rinse tanks. This change would remove contaminants in tap water including total dissolved
solids (TDS) and hardness thereby increasing  process efficiency.

       Current barrel withdrawal rates are 17 ft/min. for the automated line and 27 ft/min. for
the manual line.  According to information received from WRITAR (Waste Reduction Institute
for Training and Applications Research), the maximum  rate of withdrawal should be  about 8
ft/min. This change would help decrease the  amount of dragout  from each tank resulting  in
decreased chemical usage.

       It is  also recommended  that the hang time of the barrels over the tank  (before moving
to next station) be  increased.  The  current barrel hang time  on the auto  line is 23  seconds.
There is still significant dripping from the barrels after this time period.  The  hang  time over
tanks on the manual line varies with operator discretion. For the most part it is  minimal or non-
existent, and dragout is visually significant.
                                            14

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Acknowledgements

       The project team  acknowledges the valuable assistance received  from  all Behlen
Manufacturing employees during this study.  In particular, we would like to acknowledge Mr.
Dick  Goc, Mr.  Tony  Raimondo,  Jr. and  Rod  Gering for  their constant cooperation ami
assistance.  This  project is funded, in part, by the U.S. Environmental Protection Agency, and
in part by the University of Nebraska-Lincoln Center  for Infrastructure Research (CIR) under
the Nebraska Research Initiative. The Project Officers for the U.S. EPA are Mr. James Lund,
of the Office of  Water, Washington,  D.C., and Mr.  Carl Blomgren,  of EPA Region VII in
Kansas City.
                                          15

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    Table 3.  Summary of costs and  advantages  of recommended changes  in  the electroplating lines.
                    CHANGE
                                                                      COST
                                                                                                               SAVINGS
                                                                                     Est. Payback
                                                                                     Period
1) Lower Rinse Flow Rates
   a) auto line - after cleaning and acid pickling,
              and after electroplating

   c) manual line  after cleaning and acid pickling,
                and after electroplating
 $90 (two flow control valves)
 $50 (to hook up acid and cleaner rinses)

 $3,000 (three counter current tank)  see(3)
    $135 (three flow control valves)
24,760 gpd  see(l)
$138/day in WTX (2), sludge disposal,
and water costs

7,680 gpd
$59/day in WTX, sludge disposal,
and water costs
5 weeks
                                                                                                                                            2 months
2) Soak Cleaners and Electrocleaners
   a) increase temperature from 160F to  180F
     (auto line only)

   b) more efficient grease skimmer
   c) testing concentration of cleaning solution (daily)

   d) filtering solution (to remove dirt and metals)
$0.08/day + heat loss from tank and
solution surface  see(4)

$140 (not installed) for float valve system
(also considering a squeegee system)  see(4)
test kit free from ISA (5)

see (4)
less chemical dragout, cleaner work



less organic contamination, cleaner work

more efficient process, cleaner work

longer tank life
 see (6)
3) HC1 Acid Pickling
   a) testing concentration of acid (daily)

   b) testing iron contamination
$20 (Baume) density hydrometer) or
$0.54/test (test kit from JSA)

see (4)
more efficient process
                                            see (6)
4) Electroplating
   a) testing:
       1) iron contamination, pH and temperature,
        total  chlorides, zinc, boric acid, and wetter

   b) filtering tank solution
       1) auto line

       2) manual line

    c) peroxide  addition (daily)

    d) anode bags over titanium baskets
a total of only $7.30/week

$7,212 for 2 filtering units - one on each end
of tank (Serfilco Inc.)

$3,607 one filter unit (Surfilco Inc.)

minimal, see (4)

< $100, see (4)
more efficient process, better plating




cleaner tank solution, better plating


removal of iron contamination

capture contaminant metals and dirt
 see (6)




 see (7)


 see (6)

 see (6)
5) Chromating
   a) testing:
       1) pH, temp, and chromate concentration
   b) replace hex-chrome with tri-chrome process
no cost (time only)
see (4)
more efficient process, better conversion
coating

less toxic process, less WTX and
disposal costs
                                                                                                                                              see (4)
    (1) gpd = gallons per day
    (2) WTX =  waste treatment system
    (3) estimate from Imperial Co., in process of obtaining other estimates
    (4) In process of obtaining estimate
    (5) JSA = John Schneider Company
    (6) difficult to estimate, will result in a better product and more efficient process
    (7) difficult to estimate, will result in better plating and less chemical use.
                                                                         16

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    POLLUTION PREVENTION IN THE METAL FINISHING INDUSTRY
                      Mohamed F. Dahab
                      David L.  Montag
                          ABSTRACT
     The concept of pollution prevention has recently received
much  attention  in  the  media.    Minimizing  harm  to  the
environment by  reducing  the generation of pollution  at  its
source  is  a logical  approach to  pollution  problems.   The
University of Nebraska Lincoln (UNL)  is encouraging Nebraska
businesses to adopt pollution prevention.

     One part  of this  effort has been  a research  project
focused on industrial pollution prevention.   During 1992  and
1993, a pollution prevention project was conducted at a large
metal  finishing  company  in  Nebraska.   The  manufacturing
processes studied were electroplating, galvanizing, painting,
and tubing fabrication.

     By examining the available  literature  and interviewing
experts in the  metal  finishing industry, UNL researchers were
able  to  identify several   promising  pollution  prevention
options.  Tubing manufacture used a water based metalworking
fluid  that  was  susceptible  to  decomposition by  anaerobic
bacteria.    The  bacterial   growth was  encouraged  by  oil
contamination  from  leaking gearboxes.   This  problem  was
minimized by replacing grease  seals on the  gearboxes  and by
installing  an   improved  oil  removal  system  to  purify  the
coolant.

     The  paint  used  by  the  company  contained  volatile
solvents, which evaporate as the  paint dries and eventually
contribute  to   smog   (ozone  pollution).    Volatile  organic
compound emissions can be avoided by using coating materials
other  than  traditional  solvent  based paint.   Alternative
materials  studied  were  water  based  paint,  autophoretic
coatings, and powder  coating.  At  the  time  of this writing,
the  company  was  seriously  considering installing  a  powder
coating line.

     The galvanizing process produced large volumes of rinse
water which was contaminated with sulfuric acid, and zinc, and
which required expensive treatment prior to disposal.  A test
was  conducted  that successfully  demonstrated that a counter
current continuous flow rinse could reduce water use.   Tests
were  also  conducted  to prove  the feasibility  of using  a
                              11

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continuous  flow rinse  to remove  flux  chemicals from  the
surface  of  freshly  galvanized  parts.   These  tests  were
unsuccessful.   Testing  was  also  conducted  to  change  the
process chemistry to  avoid depositing a flux chemical film on
the finished work.   In this way, the need to rinse could be
avoided.   Unfortunately  the chemistry changes  resulted in
unacceptable product  quality, and the proposed rinsing system
was not considered feasible.  A rinse water flow reduction of
about  21  percent was achieved,  however,  by  installing  new
spray nozzles in the existing spray booths.
                              in

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                      TABLE  OF  CONTENTS
ACKNOWLEDGEMENTS  	  i
ABSTRACT	'.'.'. ii
TABLE OF CONTENTS	'. iv
LIST OF FIGURES	vi
LIST OF TABLES	vi
LIST OF SYMBOLS AND ABBREVIATIONS	vii

CHAPTER 1
INTRODUCTION  	  1
  1.1  Objectives. 	  3
  1.2  Literature Review  	  4
     1.2.1   General Pollution Prevention 	  4
     1.2.2   Barriers to Pollution Prevention 	  7
     1.2.3   Metal Finishing Pollution Prevention  ....  8
     1.2.4   Metalworking Fluid Pollution Prevention   .  . 10
     1.2.5   Paint Application Pollution Prevention ... 12
     1.2.6   Galvanizing Pollution Prevention 	 15
     1.2.7   Waste Minimization Assessment Methods  ... 19
     1.2.8   Measuring the Success of Pollution
             Prevention Programs  	 21

CHAPTER 2
CASE STUDY	23

CHAPTER 3
TUBING MANUFACTURE  	 25
  3.1   Recommended Tube Mill Changes	28

Chapter 4
PAINTING	30
  4.1   Washing	31
  4.2   Rinsing	31
  4.3   Etching	32
  4.4   Rinsing	33
  4.5   Drying	33
  4.6   Painting	33
  4.7   Flow Coating	36
  4.8   Oven Curing	36
  4.9   Painting Changes  	 37
  4.10  Water Based Paint 	 37
  4.11  Autophoretic Coating  	 39
  4.12  Powder Coating	40

CHAPTER 5
GALVANIZING	43
  5.1   Galvanizing Proposals 	 45
  5.2   Rinse Tank System	46
  5.3   Post Pickling Rinse Test	48
                             iv

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  5.4   Interim Galvanizing System  	  52
  5.5   Initial Cooling Rinse Test	53
  5.6   Dry Kettle Galvanizing	57
  5.7   Preflux Chemistry Adjustments 	  60
  5.8   Second Cooling Rinse Test	61

CHAPTER 6
DISCUSSION AND CONCLUSIONS  	  65

REFERENCES	68

APPENDIX	76

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                                                           11
          Waste Minimization Opportunities For the

           Electroplating Industry:  A Case Study

                      Mohamed F. Dahab
                         Gary  Keefer
                      John Parr,  M.S.

                          ABSTRACT

     Standard waste minimization and assessment

methodologies were applied to an aging electroplating

(manual and automated lines) facility that produced zinc

plated nuts and bolts.  The recommendations made and the

results of implemented changes are reported in this thesis.

In addition, an extensive literature review was performed

concerning waste minimization opportunities for the

electroplating process and includes sections on improving

rinsing efficiency, housekeeping, drag-out reduction and/or

return, material substitution, and recovery and recycling

techniques.

     The waste assessment involved documenting the

electroplating processes and recommending changes that would

reduce waste and increase product quality.  The most

profound change recommended dealt with the rinsing processes

after the alkaline cleaning, acid dip, and zinc

electroplating processes.  The use of countercurrent rinses

and reduced rinse flows were estimated to result in a

savings of $209.00 per day in process wastewater treatment,

sludge disposal, and water costs.  Total cost for these

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                                                           ill




recommended changes is about $4,600.00 with an overall



payback period of about 22 days.



     Some of the recommended changes have been implemented



and include: a thorough clean-up of the electroplating area



including inside and outside the tanks; regularly testing



chemical concentrations in the process tanks and making



additions as needed; the hiring of a chemist to perform the



testing and oversee all chemical processes on the lines; and



reducing rinse flow rates.  Since these changes have been in



effect, product quality has improved, as documented by a



1000% increase in white rust protection, and a 550% increase



in red rust protection.

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                                                           IV

                    TABLE OF  CONTENTS

TOPIC	      PAGE

ACKNOWLEDGEMENTS                                           1
ABSTRACT                                                  ii
TABLE OF CONTENTS                                         iv
LIST OF TABLES                                           vil
LIST OF FIGURES                                           ix

Chapter 1.  Introduction and Objectives                    1
1.1  Introduction                                          JL
1.2  Objectives                                            4

Chapter 2.  Literature Review                              5
2.1  Electroplating                                        5
     2.1.1  Electroplating Theory                          5
     2.1.2  Other Types of Metal Finishes                  6
     2.1.3  Types of Metals Plated                         8
     2.1.4  Processes involved in Electroplating           9
2.2  Rinsing in the Electroplating Process                1].
     2.2.1  Rinsing Theory                                12
     2.2.2  Requirements for Efficient Rinsing            15
     2.2.3  Calculating Contaminant Concentration         16
     2.2.4  Calculating Adequate Rinse Water Volumes      19
     2.2.5  Countercurrent Rinsing                        20
2.3  Wastes Produced From the Electroplating Process      21
     2.3.1  Make-up of Generated Wastes                   22
     2.3.2  Identifying Hazardous Wastes                  23
     2.3.3  Effluent Discharge Limits                     25
2.4  Waste Minimization Opportunities                     28
     2.4.1  Opportunities for Improving Housekeeping      28
     2.4.2  Opportunities for Increasing Bath Life        31
     2.4.3  Opportunities for Improving Rinse Efficiency  33
     2.4.4  Opportunities for Drag-out Reduction          35
     2.4.5  Opportunities for Material Substitution       39
     2.4.6  Opportunities for Recovery and Recycling      41

Chapter 3.   Overview and Application of Waste
            Assessment Procedure                          46

Chapter 4.   Case Study Introduction and Electroplating
            Process Description                           51
4.1  Case Study Introduction                              51
4.2  Electroplating Process Description                   52
     4.2.1  Overview of Electroplating Operations         52
     4.2.2  Description of Chemical Processes             54
     4.2.3  Description of Rinsing Processes              62
     4.2.4  Description of Other Processes Involved       64

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               TABLE OF CONTENTS  (Continued)
TOPIC
                                      PAGE
Chapter 5.  Methods and Materials

Chapter 6.  Results of Preliminary Testing
6.1  Testing Results
6.2  Calculating Recommended Rinse Flows From
     Drag-Out Testing Results

Chapter 7.  Recommended Changes to the Automated and
            Manual Electroplating Processes
7.1  Housekeeping Recommendations
7.2  Rinsing Process Recommendations
     7.2.1  Changes to Automated Line Rinsing Processes
     7.2.2  Changes to Manual Line Rinsing Processes
     7.2.3  Summary of Rinse Water and Cost Savings
     7.2.4  General Rinse Process Changes
7.3  Other Recommendations to the Automated and
     Manual Electroplating Lines
     7.3.1  Changes to Process Bath Operations
     7.3.2  Changes to Reduce or Contain Drag-out
            Contaminants
     7.3.3  Change to Improve Process Efficiency

Chapter 8.  Results of Implemented Changes to the
            Automated and Manual Electroplating Lines

Chapter 9.  Conclusions
REFERENCES

APPENDICES
     Appendix A;
     Appendix B
     Appendix C

     Appendix D
Testing Procedures Used to Determine
Chemical Concentrations of Undiluted
Process Tank Samples
Data From Drag-Out Testing
Calculating Recommended Rinse
Flow rates
Data from Lowered Rinse Flow
Testing
                                        65

                                        72
                                        72
                                        74
                                        75
                                        75
                                        77
                                        79
                                        82
                                        87
                                        88
                                        89

                                        89
                                        91

                                        93
 94

 99

103


108
113
123

125

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Pilot  project  adds polish
to  metal  finisher's
pollution  prevention  efforts
BY M.F. DAHAB AND JIM LUND


      AN AGING MIDWESTERN MANUFAC-
      turing facility that produces fabricated
      metal products for farm and indus-
      trial uses was chosen as the site for an
      industrial pollution prevention and
waste minimization pilot project The project
goal was to demonstrate that using appropri-
%ate management and operating procedures
can reduce the total pollution produced by an
industrial operation. The facility is a licensed
hazardous waste generator.
   The plant engages in a variety of pollu-
tion-generating activities, including electro-
plating, conversion coating, cleaning,
machining, grinding, impact deformation,
shearing, welding, sand blasting, hot-dip
coating, painting, assembly and testing. The
hot-dip galvanizing process results in pro-
duction of rinsewater containing such heavy
metals as zinc and iron. Painting processes
generate used industrial cleaners, acids, sol-
vents, and chemicals used in cleaning and
degreasing metal components.
  Process wastewaters are treated by adding  tion and minimization opportunities;
lime and polymer, and adjusting pH before      Evaluating economic and technical
discharge. Past disposal practices at the facil-  aspects of waste prevention and mimmiza-
ity had threatened area
surface and groundwater.
Waste disposal is a major
operating expense.
  Procedures and
methods. The waste-
stream evaluation fol-
lowed Environmental
Protection Agency guid-
ance. A pollution pre-
vention assessment work
plan identified several
tasks, including:
    Developing  a
detailed assessment and
evaluation of current
practices, and characteri-
zation of all wastes pro-
duced by the facility,
Past disposal
(i^fcesatBiefacity
had threatened area
surface and ground-
water. Waste dfeposal
expense.
tion alternatives, and
their short- and long-
term impacts;
   Developing rec-
ommendations to man-
agfiment       for
implementation based
on greatest benefit and
shortest payback peri-
ods;
   Providing techni-
cal assistance during
implementation of rec-
ommended alternatives;
and
   Reviewing the
results and impacts on
waste prevention after
            implementing the alternatives.
    Identifying possible pollution preven-    In developing the pilot project, empha-
            Reprinted with permission from the November 1994 issue of Environmental Solutions.
            Copyright  1994 Advanstar Communications Inc.

-------
sis was placed on areas in which the impact
on reducing total pollutant load would be
greatest  the electroplating, hot-dip gal-
vanizing and painting lines, and tube-mill
production areas. Strategy- development
stressed a multimedia approach to prevent-
ing and minimizing pollution.
   Electroplating systems. The facility
operates an automated and a manual elec-
troplating line to deposit a thin zinc film onto
such items as bolts, fasteners and nuts, which
are used to construct larger plant products.
The automatic line  is a barrel system that
plates about 145 pounds of work per load.
Barrels are moved by a conveyor chain. An
average of 145 pounds of pieces per barrel
are processed by 36 stations on the line. The
cycle takes about 3.5 minutes per station, or
about two hours per barrel.
   The work first is soaked in cleaner and
an electrocleaning solution. It then is rinsed,
pickled in a hydrochloric acid bath, and
rinsed again before entering a chloride-zinc
electroplating bath. After about an 70 min-
utes in the plating bath (20 stations), the
work is rinsed, and a light yellow chromate
finish is added. A short rinse (20 seconds)
follows the chromating process, after which
work is dried at 65 degrees Celsius.
   The electroplating solution is circulated
through a filter to remove  impurities, which
are rinsed into the treatment system. Total
rinsewater use in the automatic electroplat-
ing line, which operates eight hours a day,
was estimated at 166 liters per minute.
   The manual process requires operators
to move barrels from station to station. The
barrels are bigger, but the average load of
work per barrel is the same as in the auto-
mated process. The manual line is used more
than the automated line, especially when
plating small quantities. The work is cleaned
in a soak cleaning bath (no electrocleaning)
for about 15 minutes. It then is rinsed, pick-
 led and re-rinsed before entering the chlo-
 ride-zinc electroplating tank (Stainless steel
 pieces are dipped in nitric acid instead of
 hydrochloric acid.) Pieces are plated 60 to
 90 minutes before being removed. A short
 rinse precedes the chromate coating, which
 can be clear or yellow. After a final short
 rinse, pieces are placed on a table to dry.
    To obtain better product quality and
 ensure that the lower flow rates would not
 compromise rinsing efficiency, housekeep-
ing changes were recommended. These
included a thorough cleaning of the elec-
troplating area (tanks, floor and electro-
plating process  equipment),  and  a
maintenance recordkeeping system.
   The suggestions, designed to reduce rin-
sewater and electroplating chemical waste,
called for improved cleanliness and better
chemistry control. Also recommended was
reducing rinse rates to decrease the amount
of wastewater discharged to the treatment
plant. Reactive rinsing was recommended
for both electroplating lines to decrease water
     Use of still rinse tanks
     folio wing electroplating
     and chromating was
     recommended to
     recapture some of the
     chemical dragout from
     these processes.
 use from the rinses following pickling and
 alkali cleaning. Pickling rinsewater no longer
 would aro down the drain, but instead flow
       w
 to rinse tanks following alkali cleaning.
   Effluent from the rinsing step after the
 acid dip could be directed to the rinse tanks
 after the cleaning process, saving about 76
 cubic meters of water and $150 per day in
 waste treatment, sludge disposal and water
 costs. Countercurrent tanks similar to those
 on the automated line would be needed on
 the manual line to incorporate this change, at
 a cost of about SI,000. It was recommended
 that rinse processes following electroplating
 on both lines be changed to countercurrent
 with a rinse flow rate of 20 liters per minute
 each. About 24 cubic meters of water a day
 can be saved, saving $50 per day.
   Daily testing of chemical and operating
 parameters in the  tanks needed to be per-
 formed for several variables. Electroplating
 tank variables included pH and temperature
in addition to concentrations of cleaners, acid
dips, zinc metal, boric acid, total chlorides
and the wetting agent. Chromating tank vari-
ables included pH, temperature and chro-
mate concentration.
   Other recommended changes included
increasing the temperature of automatic line
cleaning tanks from 71 degrees Celsius to
93 degrees Celsius. Grease skimming needed
improvement, because grease originating
from the machining steps of bolt produc tion
accumulated in the automatic electroplating
line's cleaning tanks. An inoperative filter
system on  the electroplating tanks also
needed repairs. Once the repairs are made
on both lines, it should be possible to deter-
mine whether the systems are adequate to
maintain contaminants at low  levels.
Installing a  new filtering system was recom-
mended.
   Anode bags were recommended to keep
contaminants and dirt from the zinc balls
out of the electroplating solution. Addition-
ally, a drain board was needed over the drip
tank following the chromate rinse or the
automatic line to direct dragout back to the
rinse tank. By changing to a trivalent-
chrome-conversion coa'ting process instead
of the hexavalent chrome process, the facil-
ity should decrease the toxicity of the waste
it produces. This would save on treatment
costs, because hexavalent chrome must be
reduced chemically to its trivalent form 
which  is less toxic and less expensive to treat
 before  it is sent to a treatment plant.
    Some potential disadvantages of these
changes are a slight reduction in corrosion
protection, the necessity of closer process
monitoring and testing, and the tact that iiiva-
lent chrome coats are available only in bright
blue instead of the customary light yellow.
    Use of still rinse tanks following elec-
troplating and chromating was  recom-
mended to recapture some of the chemical
dragout from these processes. This
method should recapture about half of the
chemical lost to dragout. It was also rec-
ommended that air agitation be used in the
tanks to increase rinsing efficiency.
    The water supplied to the electroplating
process should be as clean as possible. It was
recommended that the facility's reverse
osmosis purification unit be used to supply
water to the electroplating, chromating and
still rinse tanks. This would remove poten-

-------
tial contaminants in tap water, including
total dissolved solids and hardness, before
its use in the electroplating line, increasing
process efficiency.
   The barrel withdrawal rates were mea-
sured at 5.2 meters per minute in the auto-
mated line and 8.2 meters per minute in the
manual line. The maximum withdrawal rate
should be about 2.4 meters per minute.
Changing this would decrease the amount
of dragout from each tank, resulting in
decreased chemical use.
   It was also recommended that the hang
time of barrels over the tanks be increased
by pausing longer before moving to the next
station. Although hang time on the auto-
mated line was 23 seconds, significant drip-
ping from barrels occurred after this time.
Hang time over tanks on the manual line
varied. Generally, hang time was observed
to be minimal, and dragout was significant.
   Results of system changes. Several
recommended changes to the automatic
electroplating line were implemented. All
tanks were cleaned, inside and outside, on
the plating line, and  accumulated bottom
sludge was removed.  The bath contents of
the electroplating tank were pumped into
a temporary holding tank, and nonhaz-
ardous bottom sludge was shoveled into
eight 55-gallon drums for disposal. The liq-
uid portion of the plating bath was pumped
back into the plating tank, and additional
chemicals and water were added to restore
them to normal levels.
   Other changes included:
     Regular testing of cleaning, acid dip,
electroplating and chromating processes to
maintain optimal-level chemical concen-
trations;
     Hiring a qualified individual to per-
form operational  control testing and work
with the plating operator to make required
chemical additions; and
     Reducing rinse flows, and installing
flow measurement  and countercurrent
rinsing.
   Flow control devices have been installed
on the rinses following the alkaline clean-
ing and acid-dip processes to maintain flow
rates at recommended levels. The two sys-
tems have not been connected as recom-
mended. Flow rates for the two rinses
following electroplating also have  been
reduced* The new rates have not been mea-
sured, so it has not been determined
whether they are being maintained consis-
tently. The plating operator reports the
valves that control flow are not opened as
tar as in the past. Besides decreasing the rin-
sewater flow rate, adding the countercur-
rent system to the manual line should
increase the rinsewater's utility.
   Product quality has been increased sig-
nificantly, as evidenced by results of the 5
percent neutral salt spray testing performed
on bolts plated on the automated line before
and after the changes occurred.  The results
      Tank cleaning, stadge
      removal and use of oi
      absorbent pads on Hie
      cleaning baths should
      reduce the dragout of
      drt, grease and other
     stream processes.
show a 1,000 percent increase in white rust
protection and a 550 percent increase in red
rust protection.
   From a waste prevention and minimiza-
tion perspective, the changes have been
effective. Reduction in rinse flows should
lead to less wastewater for treatment at an
onsite facility. Tank cleaning, sludge removal
and use of oil absorbent pads on the clean-
ing baths should reduce the dragout of dirt,
grease  and other contaminants to down-
stream processes. This will increase bath life,
resulting in fewer bath dumps and reduced
chemical use. Costs of implementing these
changes have been modest.
   The galvanizing system. The facili-
ty's galvanizing process consists of pickling,
rinsing, prefluxing, galvanizing and final
rinsing. The pickling step prepares work
for galvanizing by removing oxides from
the steel surface using a 10 percent sulfuric
acid solution at 70 degrees Celsius.
   Work pieces are rinsed after pickling.
The preferred method is to dip them in the
rinse tank, which is filled with unheated
municipal water. The rinsewater is a^tated
by moving the pieces back and forth in the
tank. After the first rinsing, work pieces are
placed in the preflux tank, a crucial step in
the dry-kettle galvanizing process. Work is
coated with flux chemicals before entering
the zinc kettle. The preflux tank is main-
tained at 70 degrees Celsius. The preflux
solution generally is allowed to dry thor-
oughly before galvanizing.
   Galvanizing is accomplished by immers-
ing steel in a tank filled with molten zinc for
two to three minutes. Most steel galvanized
at this plant uses the wret-kettle method. A
flux layer is floated on top of the galvanizing
kettle, and work pieces pass through it as they
enter and leave the kettle. For galvanizing
materials, such as building components, the
kettle flux layer is skimmed to the side and
not used. Work pieces  are cooled by rinsing
them in a second rinse booth next to the gal-
vanizing kettle. This final rinse is needed to
cool the work to below 200 degrees Celsius,
which prevents growth of a brittle zinc-steel
alloy layer. Cooling also allows operators to
handle the pieces.
   Galvanizing operations.  Pollution
prevention efforts in galvanizing were con-
centrated on reducing the volume and metal
content of rinsewater, as this is the princi-
pal medium through  which metal is lost.
Volume reductions can be accomplished by
installing additional galvanizing equipment.
Metal content reductions are possible by
discontinuing use of the kettle flux or
switching to a different kettle flux.
   The galvanizing system initially used
about 265  cubic meters of rinsewarer per
day. Flow through the first rinse booth was
measured during wastestream assessment
at 1,200 liters per minute. Freshly galva-
nized pieces are cooled in the second rinse
booth. Flow through  this booth was esti-
mated at about 1,200 liters per minute. The
rinse booths operate only while materials
to be rinsed are carried through  them.
   Rinsing in a tank instead of a booth is
the most important step in decreasing gal-
vanizing water use. Using rinse tanks after
pickling also is important.  It was recom-

-------
mended that rinse booths he replaced by
rinse tanks linked in a countercurrent flow
arrangement. This allows water to he reused
several times before being discharged and
ensures that work pieces are rinsed with clean
water as they leave the process line.
   A rinse test conducted to verity the use-
fulness of the rinse tank concept successfully
demonstrated the feasibility of continuous-
flow rinsing. Based on the results, a contin-
uous rinsewater flow rate of 24 liters per
minute removes pickling acid adequately tor
two rinse tanks in series. This flow rate cools
the work, preventing the water temperature
from rising high enough to pose  a satety
problem. The proposed system would use
no more than 35 cubic meters of water per
day,  representing a savings ot about S3 per-
cent. As a result of the study, water-saving
(low-flow) nozzles were installed in the rinse
booths. This immediately reduced water use
by 60 percent, yielding water and waste treat-
ment savings of about $250  per day.
   The proposed galvanizing  equipment
changes cost about $70,000. Ventilation sys-
tem improvements to remove pickling solu-
tion vapors from the proposed pickling tank
location would cost $25,000.  Due to the
expense, phased installation ot suggested gal-
vanizing changes was recommended. The
payback period is estimated at about 10
months.
   Livestock fencing is being fluxed twice
 once in the  preflux tank and again as it
enters the kettle. For galvanizing objects
other than  fence panels, kettle flux is not
used. The kettle flax is 98  percent zinc chlo-
ride and contains a small  amount of potas-
sium chloride. Kettle flux adds sigruficandy
 to the metal content of galvanizing rinse-
 water, so that discontinuing its use would aid
 pollution prevention.
    Pre'fluxing is crucial in dry-kettle galva-
 nizing. To obtain good fluxing, proper con-
 centrations of zinc chloride and ammonium
 chloride must be maintained, and iron and
 sulfate concentrations minimized. Frequent
 sampling is required.
    Switching from zinc chloride preflux to a
 mixture of mosdy ammonium chloride and
 some zinc chloride or ammonium chloride
 alone was recommended. This probably would
 enhance product quality, because the proposed
 countercurrent flow system (with fresh water
 being added at the final rinse tank) would not
complicate preflux chemistry.
   Another problem with the galvanizing
operation was a layer of oil floating on the
surface of the acid bath. The oil could be
minimized by installing a skimmer to remove
it periodically or to reduce oil use in the fab-
ricating step.
   The painting system. The painting
operation at the tacility consists of washing,
etching,  oven drying, spray painting and
oven curing. The plant's painting operation
in 1992 was estimated to have emitted about
37,500 kilograms of xylene and 11,000 kilo-
grams of toluene. Reducing emissions of
these volatile organic compounds should be


        Another suggestion

        was to switch to an

        autophoretic painting
        eliminate chromic
        acid etching.
 a top priority.
    Two types of paint are used at the plant.
 A solvent-based paint is used for painting
 gates, and a silicone polyester paint is used
 for coating building panels. Seventy-tour per-
 cent of the paint used in the automatic paint
 line in 1992 was used to paint farm gates.
 About 2,200 liters per month of a mixture of
 aromatic solvents are used for such purposes
 as  cleaning paint-supply piping.
    The  only practical way to reduce VOC
 emissions significantly is to change paint
 materials. One alternative is to use water-
 based paint for the gates. If water-based
 paints are applied electrostatically, a high
 transfer efficiency can be obtained. The
 investment should be relatively small,
 because the only facility change required is
 installing new spray equipment. Immediate
 testing of water-based  paints was recom-
 mended.
    Another suggestion was to switch to an
autophoretic painting process to reduce
VOC emissions and eliminate chromic-acid
etching. This involves dipping metal to be
painted into tanks filled with paint The coat-
ing is deposited via a chemical reaction
between the paint and metal which requires
several minutes of immersion. The auto-
phoretic process resembles electrocoating
but requires no electric current. Metal
painted using this process reportedly has
withstood salt spray tests up to 3,000 hours
without coating failure. The paint report-
edly exhibits a high degree of hardness and
good resistance to chalking from ultraviolet
light exposure.
   The estimated cost of an autophoretic: sys-
tem to coat gates  was $300,000. A serious
drawback of this method is that color varies
with the dissolved iron concentration in the
paint, which increases slowly due to contact
of the paint with the steel being painted.
Another drawback is the fact that a separate
paint tank is needed for each color.
   Another alternative is powder coating.
Agricultural gates are ideally suited for JKW-
der coating, because they are made in only
two colors. Transfer efficiency is not an issue,
because overspray is captured and blended
with fresh powder for reuse, and VOCs are
not emitted. An industrial supply contractor
estimated that powder coating could be
added to the existing paint line for about
$40,000. However, installation costs prob-
ably would be higher, because the automatic
paint line is old and should be replaced. A
new paint line was estimated to cost about
$200,000.
    Pollution prevention in the painting area
at this plant will not be offset by significant
savings in disposal costs.However, the Clean
Air Act will require that action be taken soon.
As a result of this study, the plant has exper-
 imented with water-based paints and
 requested bids to construct a powder coat-
 ing system.
    Tubing manufacture system. A tube
 mill at the facility forms metal pipe trom
 coils of sheet steel. The plant makes tubing
 for all its gates and also sells tubing to other
 companies. The major tube  mill compo-
 nents include a coil unwinder, feeder, ini-
 tial cold rolls, welder, re-galvanizer, final
 cold rolls, metering cutter and coolant dis-
 tribution system. A water-based fluid coolant
 is used to lubricate and cool the tube mill.

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   About 800 liters of coolant per month are
consumed at a cost of about S800. The
coolant flows from application points into
sumps below the components. The sumps
drain by gravity to a large collection tank,
which contains an oil removal system con-
sisting of a plastic tube pulled through the liq-
uid coolant. Floating oil adheres to the
polyethylene tube and is removed by a scraper.
However, the oil removal system is unable to
remove oil quickly enough.
   Oil in the coolant originates from grease
leaking out of the tube  mill gearboxes. Over
the years, oil and grease leaks have covered
the tube mill and the surrounding area.
Grease combines with metal filings created
when excess metal is  scraped from fresh
welds. Together, the grease and filings form
a black substance that fills the bottom of the
sumps in about a month. The mill occa-
sionally is shut down while operators scoop
out the grease. About two-thirds of the
coolant is lost each time the sumps are
cleaned, and this is the only time coolant is
discharged from the system.
   Recommendations for the tube mill focus
on minimizing grease contamination of the
coolant. The old oil-removal system should
be replaced with a system  that would allow
coolant reuse. A suitable unit was estimated
to cost less than $2,500. The payback period
was estimated at less than six months, assum-
ing the coolant's usable life is doubled. If
coolant could be used  longer, the payback
period would be shorter.
   The coolant also turns rancid. Coolant
rancidity usually is controlled by adding a bio-
cide. If rancidity problems  continue after an
improved oil removal system is installed, a dif-
ferent biocide may be needed. Gearbox leak-
age should be prevented or kept from falling
into the sumps through  regular maintenance.
 In addition, preventing metal filings from
 falling into the sump below the weld scraper
 would keep them from combining with the
 grease. It was recommend that the entire area
 be shut down for thorough cleaning, as this
 would vastly improve system operation.
 Cleaning should include equipment, floor
 grates and the return trough.           IT

   M.F. Dahab is an associate professor of civil
 engineering and biological systems engineering
 at the University of Nebraska-Lincoln. Jim Lund
 is director of the Industrial Pollution Prevention
 Project in the Environmental Protection Agen-
 cy's Office of Water.
   The project on ivhich this report is hosed icas
funded jointly by  EPA and the University of
 Nebraska-Lincoln Center for Infrastructure
 Research.

 More reading
   Anonymous, "Steelcase Inc. replaces zinc
 plating lines," Finishers Management, March
 1992, pp. 17-20.
   Cook, T.H., D.E. Mergen and D.L.
 Clark, "Increasing profits in hot dip galva-
 nizing," Metal Finishing, Vol. 84, No. 23,
 1986, pp. 23-27.
   Cook, T.H. and W.S. Horton, "Ammo-
 nium chloride control in galvanizing pre-
 flux," Metal Finishing, Vol. 80, No. 19, 1982,
 pp. 19-23.
   Dahab, M.F. and D. Montag, "Waste
 minimization in a metal-finishing industry:
 A pilot project,"  Third International Confer-
 ence on Waste Management in the Chemical and
 Petrochemical Industries, Salvador-Bahia, Brazil,
 Oct. 20-23, 1993.
   Dahab, ME, D. Montag and J. Parr, "Pol-
 lution prevention and waste minimization at
 a galvanizing and electroplating facility," Water
 Science and Technology, in press, 1994.
   Durney, L.J., Electroplating Engineering
 Handbook. Chelsea, Mich.: Lewis Publishers
 Inc., 1984.
   Hunt, G.E., "Waste reduction in the
 metal finishing industry, "Journal of the Air
 Pollution Control Association, Vol. 38, No. 5,
 1988, pp. 672-680.
   Montag, D., Pollution Prevention in the
 Metal Finishing Industty (master's thesis). Lin-
 coln, Neb.: University of Nebraska-Lincoln
 Libraries, December 1993.
   Sjoukes, F., "Chemical reaction*; in fluxes
 for hot dip galvanizing," Anti-Corrosnon Meth-
 ods and Materials, Vol. 37, No. 4, 1990, pp.
 12-14.
   Parr, J., Waste Minimization Opportuni-
 ties for the electroplating industry: A Case Study
 (M.S. thesis). Lincoln, Neb.: University of
 Nebraska-Lincoln Libraries, Febrairy 1994.
   Tsai, E.C. and R. Nixon, "Simple tech-
 niques for source reduction of was tes from
 metal plating operations," Hazardous Waste
 6-Hazardous Materials, Vol. 6, No. 1,  1989,
 pp. 67-78.
   U.S. Environmental Protection Agency,
 Guides to Pollution Prevention-The Fabricated
Metal Products Industry. Washington, D.C.,
 EPA Report No. EPA/625/7-90/006, July
 1990.
   	Facility Pollution Preventivn Guide.
Washington, D.C., EPA Report  No.
EPA/600/R-92/088, May 1992.
   	A Primer for Financial Analysis of
Pollution Prevention Projects. Washington,
D.C., EPA Report No. EPA/600/R-93/059,
April  1993.
   University of Tennessee Center for
Industrial Services. Waste Reduction Assess-
ment and Technology Transfer, 2nd edition,
9/22-9.
   Wentz, CA Hazardous Waste MaiiagenKnt
New York: McGraw-Hill Book Co., 1989.
                         Reprinted from ENVIRONMENTAL SOLUTIONS, November 1994
                                     AN AOVANSTAR 


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