Hazardous Waste Reduction and Me

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					W-163 Boynton Health Service                                                                           Twin Cities Area:        (612) 625-4949
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University of Minnesota                          Executive Summary
Minneapolis, Minnesota 55455

                                           1985 Summer Intern Report

                                           by Prasad M. Kuchibhotla
                        Project conducted at Sperry Corp., Roseville, MN
            Sperry Corporation is a computer manufacturer with facilities
            throughout the U.S. The Roseville Building 2 operations are
            concentrated on the manufacture of printed circuit boards and the
            assembly of computer components. Wastewater from this facility
            is treated using hydroside precipitation to remove hazardous
            materials as sludge before discharge. The objective of this
            intern project was to evaluate alternative methods of wastewater
            The results of an in-plant survey indicated that the plant
            generates an-average 60 gallons per minute of wastewater
            containing copper, chrome, lead and tin, with copper being the
            major constituent. There are also 1700 gallons per week of batch
            dumps being tree ted. The existing pretreatment system yields 2-
            3 drums of sludge per day. Chelated wastestreams and batch dumps
            are handled separately. Complete characterize lion of all waste
            and process streams was made.
            Based on this work, process modifications and layout changes were
            recommended in order to reduce waste generation to segregate
            wastestreams for pretreatment. After analysis of the waste-
            streams based on these revisions, options for waste reduction
            were identified and evaluated. The following technologies were
            seen as having possible application at Sperry Corp.:
                    o Evaporation
                    o Reverse osmosis
                    o Electrodialysis
                    o Ion exchange/electrolytic recovery
             Problems and advantages associated with these technologies are
             reviewed in the full report.
             Sperry Corp. currently spends more than $100,000 per year on
             sludge disposal and is striving to eliminate that cost and
             liability or reduce it significantly. The use of ion exchange.
             followed by electrolytic recovery of the metals was believed at
             the time of this report to be the most feasible system for

                 The Minnesota Technical Assistance Program is funded through a grant provided by the Waste Management Board.



     I am grateful to the Facilities Department of Sperry
Corporation, Roseville, Minnesota, for giving me an opportunity
to work on this project. I express by gratitude to Duane
Dittberner for helping me in this work, Will Paul for his
guidance, and other Sperry personnel for their cooperation.

     I express by thanks to Cindy McComas, MnTAP Director, for
organizing the program and MnTAP (the Minnesota Technical
Assistance Program) for financially supporting this project.

     Sperry Corporation, with its corporate headquarters in Blue

Bell, Pennsylvania, has various facilities throughout the U.S.A.

It is the major manufacturer of large and small scale computers.

The Roseville/St. Paul, Minnesota (at Building 2) operations

primarily concentrate on the manufacture of printed circuit

boards and assembly of computer components.      Hazardous wastes are

generated as a result of printed circuit board manufacturing,

component board cleaning and soldering, spray painting of frame

parts and general maintenance.

      The wastewater generated by the Multilayer Printed Circuit

Board facility is sent to the wastewater pre-treatment plant,

where it is treated for metals (primarily copper) by a

conventional precipitation method, designed by Lancy

International.      The process flow diagram of the operation is

represented in Figure 1.

      The Printed Circuit Board facility at Sperry Corporation,

Roseville,   manufactures multilayer printed circuit boards for

internal use in the manufacture of their Sperry computers.         The

process is mostly automated technology.      The equipment involved

includes photo developer, cupric chloride etcher, resist

stripper, alkaline etcher and various rinse and batch tanks.         All

these processes produce various quantities of wastewater

containing different organic and inorganic chemicals in addition

to other metals like copper, chromium, tin and lead.      Copper is

the major constituent of the waste stream with other metals present
in smaller quantities.

     The water is separated into rinse streams and batch dumps.

The rinse streams are pumped to equalization tanks, then sent to

the first stage reactor and kept under acidic medium by the

addition of sulfuric acid.     Ferrous sulfate is continuously added

to this reactor to break the chelated copper bonds.       The second

stage reactor separates the soluble form of copper as insoluble

copper hydroxide by the addition of lime solution (which is kept

under constant circulation).      Sodium bisulfite is added to this

tank to reduce the hexavalent chrome to a more insoluble form of

trivalent chrome.    These suspended particles are then
agglomerated in the third stage reactor by the addition of

anionic polymer.    Consequently, the water upon entering the

clarifier separates out solids which are pumped to a settling

tank and then to a filter press, where the sludge is removed and

collected in barrels.    The water separated out from the sludge in

the clarifier flows by gravity to a tank for pH adjustment,

where the copper concentration is also continuously monitored

before release into the sewer.

     The batch dumps (acid, alkaline and electroless copper) are
treated separately and the sludge from the treated water is

pumped out to the settling tank, where it is mixed with the

continuous rinse stream sludge from the clarifier.

     The wastewater pretreatment process produces about 2-3

barrels of sludge a day.     In addition, approximately 60 gallons/
minute of rinse streams and an average of 1700 gallons of batch

dumps a week are treated.


      Currently this wastewater, approximately 60 GPM, is treated

for its organics from photo developing, inorganics and metals.

The treatment process is a standard chemical treatment to

precipitate out the metals in the form of sludge.    The total cost

of disposal including the drum, transportation, etc., is about

$200 per drum.   Assuming that at least ten drums of sludge are

produced each week, the total cost of disposal is about $100,000

annually.    This cost is in addition to the chemicals used in the

waste treatment process, operating personal and other utilities

such as water, electricity, etc.

      In the coming few years, the number of hazardous waste

disposal sites will be reduced drastically.    EPA and other state

environmental control agencies may totally ban the burying of the

hazardous wastes.    In view of this most important reason, and the

continually increasing cost of disposal of wastes, the

environmental management personnel at Roseville, Sperry

Corporation decided to seek alternatives for sludge disposal.

      Many technologies have been developed in recent years to

effectively recover the metals in wastewater streams.     Thus, the

objective of this project was to characterize the waste streams,
and evaluate and install equipment for metals recovery at the

Roseville,   Sperry Corporation facility.

       The work began with an "in-plant survey".   This survey

included the collection of various technical, process and

analytical data on all the waste streams from the Multilayer

Printed Circuit Board Facility.

       This survey included collection of information on tank

volumes, chemical compositions of the streams of all the process

tanks, etchers, developer and gold tab lines.

       The next part of the work involved the segregation of the

waste-water streams.    Based on their acidity, alkalinity,

chelated and non-chelated properties, etc.,   it was decided that

these streams were to be segregated in order to effectively

implement the metal recovery technology.

       The old schematic diagram was modified to reflect the

current process modifications.    This process was also redrawn

taking into consideration the developments to be expected in the

next few months at Sperry.
       The next step in the process was the selection of suitable

equipment for waste sludge reduction.    This involved careful
consideration of all the data in consultation with one of

Sperry's Senior Production Engineers.    Various vendors were

contacted for technical information for this purpose.     Selecting
the equipment such as ion exchange columns, electrolytic metal

recovery and others that suited Sperry's needs involved
telephoning and visiting various off-site plant facilities to

hear about and see the efficiency of in-place operation.

      Sperry's primary goal was to eliminate sludge production

completely.     Realistically, however, the attainability of this goal

will likely be restrained by reasonable costs and equipment



      The in-plant survey data is contained in the Appendix of

this report.     A brief description and analysis of the data is

given below.

      Appendix Tables 1 and 2 contain the analytical results for

all the rinse and batch tanks (total number of tanks involved in

the process is 68), which includes pH values and concentration of

coppers chrome,    lead, and tin.       For rinse tanks and batch tanks,

the flow rates and dump schedule, respectively, are reported.

      Table 3 contains the information on the type of process,

chemical composition, temperature of operation, chemical make-up

and destination of the streams.          The plating process uses de-

ionized water or city water, depending on the type of process in

the reaction tank.

      Table 4 details the characterization of all the streams

based on the metal contents in each tank.          They are categorized

as rich or lean and chelated or non-chelated.          This is

particularly useful information because it is vary important in
the equipment selection process.         Table 5 explains the process type

and the destination of the streams.          Some of the streams do not
need any treatment and are therefore directly sewered.           They are

within discharge limits.    Table 6 provides information on sources

of water for the plating line.

     Figures 2 and 3 present the percentages of different waste-

water streams based on: acid dump, alkaline dump or electroless


     Figure 3 details the quality and quantity of dumps that

contribute to the wastewater streams each week.     This is a

material balance for Sperry's wastewater streams.

      Initially,   there was a problem of the material balance of

the waste streams coming into the treatment room.     After the

installation of flow restrictors on all the rinse tanks, it

became particularly easy to make a material balance.     Now,   it is

possible to account for all the water flowing into the wastewater

treatment room.


      Since Sperry had a general concept regarding what equipment

may be required for the recovery process, various vendors that

supply this type of equipment (Lancy International and DMP) were

contacted.   Technical information on this equipment was collected

from these vendors and Sperry is currently in the process of

selecting the most appropriate equipment.

                                    FIGURE 2.

      Percentage of different kinds of dumps in 16 week period.

AD    =       Acid dump

AKD =         Alkaline dump

ECD       =    Electroless copper dump

Total flow =      28,950 gallons.
              FIGURE 3.

Pattern of weekly dump quantities (gal.)

        As needed ECD: 570

        AD = Acid dump
        AKD = Alkaline dump
        ECD    =   Electroless copper dump
      The most commonly-used recovery technologies for

electroplating baths are: drag-out recovery, evaporation/concen-

tration, reverse osmosis, electrodialysis,   ion exchange and


      Drag-out recovery is an often overlooked method that can

recover up to 60% of the losses due to drag-out.    Evaporative

recovery is the oldest and most energy-intensive.    Reverse

osmosis is one of the newer technologies to be applied to

recovery of metals from rinse-water.    It is less energy-intensive

than evaporative recovery but it has a number of drawbacks.       One

drawback is the limitation of the membranes, which are fragile,

easily fouled and difficult to replace; second is that the

effluent from this process is not very concentrated due to

pressure limitations.    The major economic factor is the life of

the membrane, which is short, even under ideal working conditions.

      Electrodialysis is more energy efficient than reverse

osmosis but it is also a membrane technology and so has similar

limitations.    Both reverse osmosis and electrodialysis require a

high level of skill on the part of the operator and should be

closely monitored.

      Ion exchange is the most energy efficient of the recovery

methods.   Metals can be selectively recovered as a slab using
an electrolytic metal recovery cell.

      A more practical way to achieve a high surface area cathode

where the metal can be taken out as slabs is to use stainless

steel wool or a porous carbon for the cathode.     The use of carbon

fibers increases the surface area 25,000 times and hence more

metal is removed even-at the low concentrations.    This process of

electro-winning and electro-refining can be achieved with a

recovery cell manufactured by Metal Removal Systems (MTS).

After metal removal, the remaining water can be disposed of to

the sewer.

     Currently,   Sperry is in the process of designing and

evaluating equipment.    This is a very important and interesting

part of the project.    With the help of retained consultants (who

are concurrently in the process of collecting some kinetic data

from the waste streams) and Sperry's Senior Production Engineer,

Sperry is well on its way to choosing the best design for

its needs.

     A preliminary design of the equipment was made based      on   the

segregation and properties of the streams.     The details of the

work are shown in Figure 4.    The rinses and dumps are separated

into chelated and non-chelated constituents.     The total flow

rates and total concentrations of each metal in the segregated

streams were calculated.    Based on the available capacities of

ion-exchange columns and electrolytic cells, the streams were
directed to different equipment.    Chrome rinses and dumps are to

be separately treated: the process is not yet finalized.       The
nitric strip solution, where there is major copper constituent,

presents an additional unresolved recovery problem.     Now,   Sperry

is looking at the practical aspects of this preliminary design to

recover most of the metal without drastically affecting the

efficiency of the equipment.


       The technology that will be proposed for the recovery system

involves significant capital investment.      The purchase of ion

exchange columns, electrolytic recovery cells, a sludge dryer and

piping layout modification are the primary cost incurring

portions of Sperry's project.      An investment of this magnitude

is justifiable based on the following reasoning:      The production

of a hazardous waste sludge, while resulting in an acceptable

discharge effluent, represents a tremendous liability to any

company.    Currently,   most sludges are either landfilled in bulk

or 55-gallon drums; while this may be expensive, it does get rid

of the waste.    Unfortunately,   it does not eliminate the "cradle

to grave" liability associated with it.      All hazardous waste

landfill sites are someday likely to be on an EPA clean-up list

(no site is 100% secure).      When this happens it almost always

costs all the contributing generators.      To avoid this scenario a

generator's best alternative it to generate as small a volume of

hazardous waste as possible.      For large or small companies, metal

recovery can not only achieve this goal but also recycles a

valuable resource and promotes a safer environment.      Metals

recovery is not just economical to large companies.      A number of

technologies are available to the small generator which can be

scaled down for small volumes to recover metals cost effectively.

This is especially true when one considers the cost of sludge

disposal in the future and the potential future liability.


        An expansion of about 20 additional tanks to the existing

electroplating line is expected in the near future.     The new

Printed Circuit Development (PCD) laboratory is nearly complete

and the operation of their electroplating tanks may begin at any

time.     In view of these two recent developments, some additional

wastewater (as rinses and dumps) is expected to be treated for

recovery.     An in-plant survey will be done for the above

mentioned new processes.     This survey will add to the already

collected information and will be used in the selection and

sizing of recovery equipment.


                                            TABLE 1.                             July 25, 1985
                                        CONTINUOUS RINSE
TankNo.         pH         Cu, mg/l    Cr, mg/l    Pb, mg/l    Sn, mg/l   Flow,GPM
                          (0.95-1.0) (220-260)
    3         2.95                                                           5
                              1.2       210
                          (0.1-0.25) (0.10-0.45)
    6         5.93                                                           3
                            <0.l        40.1

    9                     (8.8-20.5) <0.05-0.05)
           4.6-5.94                                                          3
                             2.2       < 0.1

   13         3.62        (0.2-0.3)    (<0.05)
                              0.5       <0.1                                 3

   17                    (0.15-0.50)
           4.72-5.93       40.1                                              5
                                                    40.2          1.0
   20          4.51                                                          3
                                                    (0.2        (1.0
   25                      (1.0-2.7)
               4.91                                                          3
                         (10-45)                   (0.2-2.2)
   33          4.63                                                          3
                              4.1                     10          2

   37                     (0.2-1.1)
               5.07                                                          5

   39                     (2.6-6.8)
            4.95-5.12                                                        3

   48                     (3.8-12.0)
            5.06-5.23                                                        3

   52                       (<0.05)                (0.9-1.6)
               5.18         40.1                                  <1.0       3

   59                     (35-48)                  (<0.21
            5.3-5.39         0.8                                             3
                                                    40.2        < 1.0

   63                     (2.4-3.8)
            5.51-5.58                                                        3

   67                    (0.05-O.1)
            5.7-5.83                                                         3
Alkaline                                                                             Operates
Etcher                      0.9              Total Chloride: 60 PPM          8
Resist                                                                               Operates
Stripper       6.64          0.1                                            20
                                                                                      15 hrs/day

NOTE:   The values in the parantheses are taken on 6/84
        Ihe values without parantheses are taken 7/85
                                 SYSTEM BATCH DUMPS
Tank No.   pH         Cu, mg/l     Cr, mg/l    Pb, mg/l   Sn, mg/l    Dump Schedule; weeks

                                                                     Operates at 90-170°F.
    1      0.03            1,750      928,000                        Returned to Vendor.
                                                                        16 weeks.
    2      0.02            1,200      861,000

    5      4.00                65          85                                    2
    8      9.4                 60        < 2                          130 F, 2

   11      0.96            8,200         < 2                                         2
   12      0.7                 50                                                2
   14      0.49              250                            < l                      8
   15      2.05                 3.7                        4 1                       8
   16      0.22               125                         8,000                      8
   19       1.7                40                            43                      3
   22      12.61           3,200                                     (
   23      4.5             3,200                                     ( As needed
   24      2.48            3,200                                     (
   28      0.54               580                                                2
   29      0.28            16,400                                    (
                                                                     (                   11
   30      0.57            18,300                                    (
   31      0.3         24,700                                        (

   34      0.1         110,000                                                   1
   36       1.78              580                                                1
   38      0.73             7,300                                                        2
   40      0.5                 90                                                    2
                             TABLE 2.   (continued)

TankNo.   pH      Cu, mg/l      Cr, mg/l     Pb, mg/l   Sn, mg/l    Dump Schedule; week

   41     0.84      18,000

   42     0.64      17,100

   43     0.33      20,600

   44     0.35      19,200
   45     0.4       17,600

   46     0.39      21,400

   47     0.44      16,200

   50     0.38      18,000

   51     1.27           4                    10,200       15,100              13
   54     1.35           2                        50          100          1

   55     1.1            4                    11,400       14,400              13

   56     1.0          <2                     12,000       14,400              13

   57     0.96          25                    11,000       14,900              l3

   58     11.21         20                                                     2

   62     0.29       1,000                                                 1

   66     10.05         20                                          Operates at 200°F.

                                        TABLE 3
                          PLATING LINE PROCESS PARAMETERS
                                                      Tank Volume   Chemical    Schedule     Destiny of
TankNo.    Process Name   Chem. Comp.     Temp. F        (Gal.)     Make-up      (Weeks)     the Stream

     1,2   Org. Etch      CrO3              150           170       13 gal.        16        AD

      5    Reducer        Na2S2O5           RT            160       100 lbs.        2        AD

      8    Soak           Alk. Clean        150           170       10 gal.         2        AKD

     11    Sodium         Na 2 S 2 O 8      RT            170       62 lbs          2        AD
           Persulfate     H2S04                                      3 gals.
     12    Acid           H2SO4             RT            160       13 gal.         2        AD

     14    Pre-dip        HCl               RT            160       5 gal.          8        AD
                          Pre-dip                                   balance
                          (mixture of
                          inorg. salts)
 l5,16     Activator      HCL               RT            170       5 gal.          8        AD
                          Activator                                 5 gal.
                          Pre-dip                                   balance
     12    Conditioner    Acid              RT            160        25 gal.        3        AD

22-24      Electroless    Copper Mix        RT            170        15 gal.    As needed    ECD
             Copper       (Copper Salts,
     28    Acid           H 2 SO 4          RT            160        13 gal.        2        AD

 29-31     Copper Plate   CuSO4             RT            300        70 gal.       11        AD/CT1
                          H2SO4                                      26 gal.

     34    Nitric Strip   HNO3              RT            160        90 gal.        1        AD

     36    Acid Clean     Cleaner           150           170        50 gal.        1        AD
                          (Org. acid,
     38    Sodium         Na2S2O8           RT            170        225 lbs        2         AD
           Persulfate     H 2 SO 4                                     3 gal.
40         Acid           H2SO4             RT            160         13 gal.       2         AD

41-47,50   Copperplate    CuSO4             RT            300         70 gal.      11         AD/CT1
                          H2S04                                       26 gal.

     51    Solder         HBF4              RT            300                      13         AD/CR
                          Sn + 2
                                     TABLE 3.    (continued)

                                                         Tank Volume   Chemical   Schedule   Destiny of
Tank No.   Process Name   Chem. Comp.      Temp. F          (Gal.)     Make-up     (Weeks)   the Stream

   54      Acid           HBF4                  RT           160       l3 gal.         1     AD

55-57      Solder         HBF4                  RT           300                      l3     AD/CT2
                          Sn 2

  58       Alk. Clean      Alkali               150          170       100 lbs.        2

   61      Copper Chloride from CuCl2           RT           170       170             1     AD

   63      Acid             HCl                 RT           160        26 gal.        1     AD

  65-66    Oxide treat    NaOH                  210          170       1.2gal.(50%)   16     AKD
                          Na3PO4                                        16 lbs.
                          NaClO3                                        50 lbs.

                                   RT    = Room Temperature
                                   AD    = Acid Dump
                                   AKD =    Alkaline Dump
                                   CT1 = Carbon Treatment 1
                                   CR = Carbon Treatment 2
                                   ECD = Electroless Copper Dump
                                      TABLE 4.

                             COPPER         CHROMIUM           LEAD            TIN- -
Tank No.   Chelated       Rich* Lean      Rich* Lean
                                               -           Rich*
                                                           -        Lean
                                                                       -   Rich* Lean
    1                        X
    2                        X
    3                              X
    5                        X
    6                              X
    8          X         x
    9                        X
   11                        X
   12                        X
   13                              X                X
   14                        X                                                       X
   35                        X                                                       X
   16                        X                                              X
   17                              X                                   X             X
   19          X             X                                              X
   20                              X                                                 X
   22          X             X
   23          X             X                                         X             X
   24          X             X
   25                              X
   28                        x
   29                        X
   30                        X

   36                        X
   37                              X
   38                        X
   39                              X
   40                        X
   41                        X
   42                        X
TABLE 4.   (continued)

                                        TABLE 5.

     PROCESS NAME                          DESTINY OF THE STREAM

1. Gold Tab                                Continuous Rinse (max. 10 GPM)

2. CuCl2 Etcher                             1. Vendor
                                           2. Tank 25 & final pH adjustment
                                           3. Sewer

3.     Deburr                               Sewer

4. Alkaline Etcher                         Continuous Rinse (max.   10 GPM)

5. Scrubbers                                Sewer

6. Developer                               1. Sewer
                                           2. Tank 25 & final pH adjustment
                          TABLE 6.

Total rinse flow of DI Water          6 gpm
Total rinse flow of City Water       48 gpm