'' Beyond Compliance In today's competitive metal finishing industry, PW- efficiency i s the key to success ...

by GRtchen Gillespie, &vilumxe solrrtions

Thattef6ciMcymustnowabmdto

regulations and the associabed costs ofcvmpHaneAsoneofthelargest metal finkhing job shops in the Chicago area. C J. SapolitO Plating C o m p y mnfmnted this ongoing WengeTypicaIofmcstjobshops, saporit0 employs a bmad array of platingpmzessestoao"odatea highlydiveKsiedcustom€Tbase.

the - tightening envimmenM

with various types of generated

ment pluedlms proved edmnely

Wastes, implementing affordable and sucessfd wastewatex treat-

challenging. Initidy, the company's sole inhouse treatment consisted of a traditional metal hydroxide precipitation p~ocgs. This technol- ogy did not satisfy the intemal waste "izatisr \bjectives set forth by the company. Thedore, a seaxh for alternative waste mini- mization processes was initiated. In the summer of 1990 the Head of Operations, Environmental En- gineer Regulatory Manager and En- vironmental Consultant, teamed together to address tightening

oneffiaq.Inatwoyearsearchfor answers, saporit0 learned a great deal. This is a story of that journey and what was Ieamed.

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--- * s- RNI-IO REMOVES WASTE WATER

CONTAMINANTS

8 FI-- Appliwliomlndnde: f Emulsified Oils Washdown Water J

4 Vibratory deburring , suspended wids Ei finishing d in Waste Water Metalworkingla"

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Parts Washer Water HeavyMetals

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COUOlO ENVlRONUENTAL TECHNOLOGES COMPANY

l%X?WerlSnmeDrive- A.rlinglon Heignls. IL 6 0 W la%- US& lTJ2.58M. lek. I l l 433ou1 . F & X 708606.6150 ," , , .

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Factors For Implementation

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In the past the company has repeatedly demonstrated foresight in their continual efforts to optimize pmcesses. This includes madmized inventory cost contml. continuous- ~

ly impmved chemical usage, and in- novative waste minimization process techniques. There are several examples of changed processes or implemented tech- nologies early in their development despite the presumed risk and cost. For example, in looking to eliminate cyanide from all processes, the com- pany prompted the research and development efforts of a popular

MAXI- POLISH POUSHES WASTE IREATMENT

DISCHARGE TO LESS MAN 0.5 ppm

0 TOTALLY AUTOMATIC - SELF CLEANING 0 NO LABOR MPENSE 0 PERMANENT MELW

16 FINISHERS' MANAGEMENT, JUNUJULY 1994

DIRECTION OF FLOW - > . F L O W CONTROL

- C O U N T E R . F L O W RINSE TANK

I PUMP

4b

1 b

Q U A L I T Y F I L T R A T I O N I N D I C A T O R

D E V I C E

Figure 1. Cadmium Metal Recovery Deionizer System: Recirculation To Rinse Tank.

chemical supplier. As a result,Sapo- electroplaters with cyanide-free Frequently these initiatives in- r i t o w a s o n e of t h e f i r s t cadmiumandzincbaths. clude the use of vendors or consult-

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CONSIDER THIS ... Our minimum waste ion exchange systems eliminate over 80% of the regeneration waste by proprietary regeneration tech- niques, makiig evaporation economically feasible. This allows for a truly "zero dis- charge" system. For more information:

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17 FINISHERS MANAGEMENT, JUNUJULY 1994

ants specializing in the metal finish- ing industry, which provide a fresh perspective to particular situations and the detailed information neces- sary to research technology. Given the historical successes of outside resources, the company used the same strategy in addressing waste minimization. An industry en- gineer, familiar with the plating and anodizing facility, was brought in to work withthe project team. The con- sulting engineer brought a needed perspective to the project: the

knowledge that comes from years of experience gained from handling similar problems in a variety of situations.

The first step was to completely understand where, how and why the waste streams are generated. This sounds elementary, but it is es- sential in selecting efficient waste minimization processes to address each issue within the facility No one standard treatment system can effi- ciently handle the varied streams generated in plating shops. But the

Leadineedge, costaeffective solutions for your process

recycle, reuse, ind discharge compliance requirements.

We will evaluate your present wastewater treatment and recommend the best system for the recycling and reuse of your process rinsewaters. We'll also recommend the best way to separate toxic heavy metals and residual organics for discharge compliance.

Pilot systems available to demonstrate effectiveness in your plant.

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Prosy5 Corporation, 187 Billerica Road, Chelmrford, MA01824

- - - - - - - - - -

Tel: (508) 250-4940 Fax: (508) 250-4977

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. . . ' smart application of various iech- nologies on segregated streams can be the solution.

The first decision made was that ion exchange held the most promise for achieving the basic goals. Numerous ion exchange vendors were contacted and various designs, implementation plans and system prices were discussed. The topic of cost was important to confirm affor- dability prior to further work. Once cost was determined, selection of an ion exchange supplier was next. Be- cause of the wide variety of proces- ses within the facility, developing a practical system required careful planning and commitment. This in- cluded a vendor who provided:

An understanding of resin

.

technology and how to apply it to metal finishing applications.

numerous processes and waste streams. Ion exchange expert for the project team. Ion exchange service rather than just capital equipment, thereby reducing capital outlay Off-site regeneration and recovery capability thereby eliminating in-house recovery and reducing disposal costs and liability. Flexibility and credibility of ion exchange products and services. The supplier selected was Enviro-

Pure Solutions, (formerly known as Interlake Environmental Systems, of Broadview, Illinois) because it also had the ability to reduce "cradle to grave" responsibilities associated with hazardous waste generation without having to become recovery specialists.

The ion exchange service eliminates the hazardous nature of waste by producing metal by- products and chemicals from the regenerant at an off-site resin regeneration facility. These former F006 wastes are converted to valu- able materials and are reused in a variety of industries. This means the amoun t of hazardous waste produced is dramatically reduced, satisfying waste minimization

Assistance in analyzing the

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18 FINISHERS MANAGEMENT, JUNE/JULY 1994

FILTRATION I 1 I 1 CATION CATION ANION ANION

Figure 2. Chrome Metal Recovery Deionlzer System: “Closed-loop” and Self Regenerating.

regulations, fulfilling internal objec- tives and eliminating environmen- tal liability.

An appealing aspect of the system was inherent flexibility. This is in- creasingly important as a variety of process lines are adopted and aban- doned in efforts to meet the demands of a diverse customer base. This is especially valuable given the promise of new plating markets such as zinc-nickel and black chromate processing. Because the ion exchange service system is modular, system changes are easy to execute.

Feasibility Study After reviewing the project goals,

the next step was to study each waste stream targeted for ion ex- change. This stage was more critical to achieving design goals than pre- viously thought. Using sampling and testing of rinses planned for treatment, lab analyses and bench- top ion exchange column studies were completed using these samples. The results were used to develop the system’s process design and sizing and determine operating performance, effluent quality, regeneration frequency and operat- ingcosts. Proper andvalid sampling representing average conditions and identifying minimum and max- imum contamination levels are ex- tremely important to a successful

FINISHERS MANAGEMENT, JUNE/JULY 1994

Circle 17 on Postcard

19

feasibility program. If a too limited sam- pling is done, the system's process design will be based more on a snapshot of the rinse water con- tamination rather t h a n t h e actual average rinse water conditions.

The study indi- cated excessive ionic contaminants due to tap water impurities. Both softened and deionized make-up feed water to the rin- s e s w e r e i n c o r - p o r a t e d i n t h e d e s i g n . T h i s p r e t r e a t m e n t -moves the normal tap water ions which otherwise compete for capacity in the

120

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C.J. Saporito Plating Company Zinc System FEED & WORKER ANALYSIS .llll...lll "_l .... "

EXCHPNGE I A - m Zn FEED

e x h a g e Figure 3. Analyses Indicates ion exchange regeneration frequencies, columns, thereby causing shorter bed

A// C/arifier Sysfems Are NOT Creafed Equal

Optimum wastewater treatment requires more than standard equipment components. It reqJires appropriate cnemical pretreatment and a complete integrated system of segregation. pretreatment. sett.ing. dewatering. ano slLdge handling.

Memtek, with over 300 clarifiers installed. is a recognized expen in wastewater management. We develop specific pretrearment and integrated oesign to make a clarifier system work effectively.

We offer complete turnkey capabilities, from treataoility testing ana integrated system deslgn to installation, srarl-up. and regLlar service. Our system components include:

-. _. .. . .

I----

Inclined plate settlers Multimedia filters TOTALTREAT'" compact clarifier systems Tanks, filter presses, and all auxilliary equipment

We are committeo to meeting yodr wastewater treatment needs wdh the most effective so ld on. Call 1-800-527-0433 for information. I hi Wheehbrator Engneered Systems lnc: Memtek

28 Cook St., Billerica, MA 01821 (508) 667-2828 Fax (508) 667-1731

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20 FINISHERS' MANAGEMENT, JUNE/JULY 1994

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life, higher regeneration frequencies and increased costs. Generally, when deionized water is incor- porated, the system can acclimate a closed-loop design allowing for full reuse of the water.

Process Design Treatability was determined for

each of the 80 flowing rinses in the facility. Metal content, concentra- tion and compatibility determined the design of the system. Each rinse required a specific method of treat- ment so a scheme was designed to segregate the compatible rinses and direct the various wastewaters to their proper treatment area. By segregating the rinse waters, cross- contamination between the metals is eliminated, making ion exchange treatment easier and leaving a purer metal on the resin for off-site reclamation.

Thirty small segregation tanks were installed at various points throughout the plant to serve as holding areas for the untreated water. Several rinse tanks may share a segregation tank based on the metal in the rinse and proximity to a particular tank. Each segregation tank has a float-activated pump to transfer the water, via overhead pipes, to the centralized ion ex- change system. The rinses to be t reated by metal-hydroxide precipitation flow by gravity through underground pipes to the collection pit for this conventional treatment.

The ion exchange system was finalized, equipment ordered, in- stalled and started-up in September of 1992. The final design included six separate systems working in unison to remove all metals of con- cern. These include hexavalent and trivalent chromium, cadmium, nickel, copper and zinc. The use of separate systems was implemented to provide for the segregated recovery of the metals. Mixing the metal types would severely limit the recovery options and increase costs.

To complement the ion exchange system, Saporito removed the exist- ing precipitation system and in- stalled a smaller and more efficient metal-hydroxide precipitation sys-

tem. This system is used for rinses not compatible with ion exchange technologies, as well as for spent acids, cleaners and other various bath dumps.

Cadmium System Design All six systems have similar

process design feahves for remov- ing metals and to allow reuse of the water. The cadmium system treats two separate cadmium plating lines at the facility, each with rinses for cleaners, acids, and plating baths. Flowing water from cadmium plat- ing and acid rinses gravity feeds into the cadmium segregation tanks behind each line. Each runs at three

gpm for a total system flow of twelve gpm. Contaminantsrange in concentration from 30 to 50 mg/L cadmium and to 15 mg/L iron.

The water is then pumped to a large collection tank where it is held and pH adjusted if necessq. The wastewater is prefiltered to remove particulates, then runs through a series of three canisters (Figure I).

Canister 1 has a bed of activated carbon to remove any organics such as starters or brighteners. The wastewater is then passed through two canisters each containing cation resin.

In the cation worker, or canister 2, the positively charged cadmium

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FINISHERS MANAGEMENT, JUNE/JULY 1994 21

ions are adsorbed into the resin, and hydrogen ions are liberated into the water. The effluent of the cation worker is generally less than 0.1 mg/L cadmium metal.

Canister 3, or the cation polisher, removes any residual cadmium that may have passed through the cation worker. The effluent is then pumped back to the two cadmium lines to be used in cleaner rinses. The slightly acidic nature of the effluent, due to the excess of hydrogen ions

generated, aids in the cleaning cycle. Not only is the amount of fresh water needed for the line reduced, but the quality of the water has im- proved. After the water is used in the cleaner rinses, no further treat- ment is needed prior to discharge except perhaps pH adjustment.

Copper, Nickel, Zinc Systems Process Designs

The nickel, copper and zinc sys-

Circle 20 on Postcard

tems process designs are almost identical to the cadmium system. The copper system differs from the others in that it is of a smaller scale and the effluent is not recycled due to the small water flow. Instead, it is pH adjusted, if needed, and dis- charged.

Closed-Loop Chrome Removal

The chrome system has several process differences compared to the other systems. This system is a com- pletely self contained "closed-loop" design and the resins and media used are different from the other systems due to the nature of the chrome metals. Because both hexavalent and trivalent chromium are used in the various plating processes, a method was required to remove both species in the com- bined waste streams. Hexavalent chromium exists as an anion and can only be removed using cation resin. The resins are used in series with no complications. There are methods where all the chromium could be converted to the trivalent species, but they were rejected by the project team, because the chemistry is not conducive to the predefined goals.

The water from various chromat- ing and chromic acid rinses is pumped through segregation tanks to the ion exchange system and prefiltered for solids removal. The overall rinse water contains about 20 to 30 mg/L chromium, mostly hexavalent, and flows at 60 gpm. The water is not carbon filtered for several reasons, but mainly duk to the limited amount of organics in the chromating process. The water f lows through two canisters (worker and polisher) each contain- ing special an ion resin for hexavalent chromium removal. Since most of the chromium is in the hexavalent form, the anioncanisters are changed more frequently

It was originally planned that the effluent from the anion resin, be- cause of the excess of hydroxide ions, would be returned to the plat- ing lines with an expected pH > 7.

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22 FINISHERS'MANAGEMENT, JUNE/JULY 1994

.. - However, due to other anionic species in the waste water, the pH of the effluent soon dropped below usable levels even though the resin canisters were still removing the metals. The system was later modified to incorporate on an on- site regenerating anion unit at the end of the chrome train. This addi- tional anion unit was installed to reduce the system operating costs.

This system keeps the pH high by introducing additional hydroxide ions into the effluent. Use of an on- site regenerating unit contradicted the project's original goals, but was utilized because the unit does not remove any metals a n d the regenerate from the system is not difficult to treat. Treatment consist of pH adjustment and discharge. This system has worked very well and the complete recirculation of water has been successful.

System Performance Tips

With all the systems at Saporito, the metal is removed from the waste stream in the worker canister leav- ing the polisher canister to catch any trace metal breakthrough that may occur. Once breakthrough of the tar- get metal on a specific canister oc- curs at a significant level (equal to the influent ppm level), the canister is considered spent and must be removed for regeneration. Analyses performed on each canister effluent indicate when exchanges must be made (see figure 2). Once the spent worker is pulled from service the former polisher is moved into the worker position, and a new canister is placed into the polisher position. This process ensures that no metal passes through the system, and that canisters are not exchanged too early Ongoing analyses of each sys- tem effluent is critical to determine exchange frequency trends, provid- ing for optimum exchanges and cost efficiency.

The use of untreated tap water for any make-up to replace water loss due to dragout and evaporation should be minimized. Tap water contains many ionic species which will compete with the target metal for capacity on the resin. These ions

can be easily and economically removed with a tap water treatment system. Hardness contaminates such as magnesium, calcium and dissolved iron can be removed with a water softener.

Removal of all the tap water im- purities, beyond the hardness ions, is recommended when reuse or a "closed-loop" process is preferred. This allows the metals recovery ion exchange system to remove only those contaminates generated from the process itself. Use of tap water deionization is cost justified given the significant savings in water and sewer costs. The Saporito chrome system utilizes a separate tap water

deionizer for all make-up water ad- ditions.

System Performance Evaluation

During the planning stage, goals were set which would justify the in- stallation of the ion exchange sys- tem. These goals were to:

1. Meet Discharge Requirements

First and foremost was the goal to continue to comply with the dis- charge guidelines prescribed by the Metropolitan Water Reclamation District of Greater Chicago.

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FINISHERS' MANAGEMENT, JUNE/JULY 1994 23

2. Reduce waste generation, along with related costs and liabilities.

Before the installation of the ion exchange system, all wastewater was treated by metal-hydroxide precipitation, which produced a sludge that was treated and landfilled. Not only is the sludge ex- pensive to treat, but Saporito, as the generator, is liable for the sludge in- definitely due to "cradle to grave" responsibilities. The ion exchange

system has reduced the amount of sludge produced, cut the costs of treatment and landfilling, and reduced future company environ- mental liabilities.

3. Reduce water usage and related costs

After the installation of the ion ex- change system in September of 1992, the reduction of water con- sumption was targeted to reduce operating costs. Water recyclingwas made possible through planning of

Recycling technology from EPI. Environmentally sound. Economically efficient.

U

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the ionexchange system. Prior to the installation of the ion exchange sys- tem water was used at the rate of 160 to 170 gpm. But due to recycling it has been cut to 110 to 120 gpm, while the plating lines have benefited from an increased recirculating water flow and increased rinse water quality.

4. Reduce operating and maintenance costs

Another area wherecost reductions have been realized is in system main- tenance. Where the precipitation sys- tem required constant attention, the ion exchange system needs minimal supervision. Brief inspections are performed daily to make sure all equipment is functioning properly, i.e. that filters are not clogged, and that pH adjust chemical tanks are filled. Periodic cleaning and routine maintenance are required to keep the system running at peak levels. Analyses are done three times a week on each canister effluent to predict when a canister will be spent and will require changing (see Figure 3). All analyses are loaded onto a computer to chart trends and to facilitate ef- ficiency improvements.

5. Reduce treatment problems If a problem comes up segregation

makes it easy to locate and remedy. If a particular segregation tank has a contamination that is not com- patible with the ion exchange sys- tem, it can be shut off and the water

Waste/powder volume comparison Recycling ends a generator's paint waste liability and meets

U.S. EPA guidelines for waste reduction protocols.

can be sent to the precipitation sys- tem. Once the problem has been rec- tified, the segregation tank can resume its designated purpose.

Conclusion Call us and learn how to recycle

End your paint waste liability By relying on state-of-the-art ion exchange technology, CJ. Saporito Plating Company has proven ion exchange technology as applied to waste minimization. Not only does this waste treatment approach keep the company in compliance, but it has enabled them to maintain their reputation for technology leader- ship in the industry. Finally, having implemented the system some twenty-one months ago, Saporito can conclusively confirm the achievement of their goals. El

24 FINISHERS MANAGEMENT, JUNE/JULY 1994

ENVIRONMENTAL PURIFICATION INDUSTRIES 419-727-0495 FAX: 419-7274 595

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