EPA-600/2-77-241
December 1977
Environmental Protection Technology Series
                   CLOSED  PROCESS  WATER LOOP  IN
       NSSC CORRUGATING  MEDIUM MANUFACTURE
                                  industrial Environmental Research Laboratory
                                       Office of Research and Development
                                      U.S. Environmental Protection Agency
                                              Cincinnati, Ohio 45268

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                RESEARCH REPORTING SERIES

Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology.  Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:

      1.   Environmental  Health Effects Research
      2.   Environmental  Protection Technology
      3.   Ecological Research
      4.   Environmental  Monitoring
      5.   Socioeconomic Environmental Studies
      6.   Scientific and Technical  Assessment Reports (STAR)
      7.   Interagency Energy-Environment Research and Development
      8.   "Special"  Reports
      9.   Miscellaneous Reports

This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia  22161.

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                                              EPA-600/2-77-241
                                              December 1977
               CLOSED PROCESS WATER LOOP
         IN  NSSC  CORRUGATING MEDIUM MANUFACTURE
                          by

                  Gerald 0. Walraven
                   William R. Nelson
                   Peter E. DeRossi
                  Richard L. Wisneski
               Green Bay Packaging Inc.
              Green Bay, Wisconsin  54305
                  Grant No. S-800520
                    Project Officer

                    Ralph H. Scott
             Food and Wood Products Branch
Industrial Environmental Research Laboratory-Cincinnati
                Corvallis Field Station
               Corvallis, Oregon  97330
     INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
          OFFICE OF RESEARCH AND DEVELOPMENT
         U. S. ENVIRONMENTAL PROTECTION AGENCY
                CINCINNATI, OHIO  45268

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                           DISCLAIMER


     This report has been reviewed by the Industrial Environ-
mental Research Laboratory-Cincinnati, U. S. Environmental
Protection Agency, and approved for publication.  Approval does
not signify that the contents necessarily reflect the views and
policies of the U. S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorse-
ment or recommendation for use.
                               11

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                            FOREWORD
     When energy and material resources are extracted, processed,
converted, and used, the related pollutional impacts on our en-
vironment and even on our health often require the new and in-
creasingly more efficient pollution control methods be used.  The
Industrial Research Laboratory - Cincinnati (IERL-CI) assists in
developing and demonstrating new and improved methodologies that
will meet these needs both efficiently and economically.

     This report describes means and methods employed to develop
a nearly closed system for wastewaters produced from the manu-
facture of neutral sulfite semi-chemical corrugating medium, a
significant portion of the effort concerning in-plant recycling
and control.  This program has been supplemented by the first
full-scale commercial reverse osmosis system operating in the
pulp and paper industry.  The reverse osmosis facility is employ-
ed to process those accidental losses not controlled by the in-
plant recycling system.  The combination of tight in-plant con-
trol and reverse osmosis processing has permitted the industry to
satisfy discharge permit requirements without the use of any ex-
ternal treatment for wastewaters.  The information will be of
value to other segments of the industry, consultants and reverse
osmosis equipment suppliers.  For further information please con-
tact the Food and Wood Products Branch of the Industrial Environ-
mental Research Laboratory, Cincinnati.

                       David G- Stephan
                           Director
         Industrial Environmental Research Laboratory
                          Cincinnati
                               111

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                            ABSTRACT

     From 1972 to 1976, the Green Bay Packaging corrugating mill
was redesigned to reuse enough water to nearly close the pro-
cess water system.  Less water enters the system during the
cooking of chips and repulping of secondary fiber than leaves
the system with the sheet to the paper machine dryers.   Many
small, dilute water streams, therefore, can be brought into the
system without upsetting the water balance.

     When extraneous water inputs do upset the system balance,
the condition is correctable by removing water, using either
thermal evaporation or reverse osmosis,  The reverse osmosis
plant design operating performance and economics are described.
Although many reverse osmosis operating problems have been
solved, flux rates are somewhat lower than had been predicted.
Other system additions and revisions for process water entrap-
ment, recycling, and surge protection are described.

     A monitoring system is in use for early spill detection
and problem correction.  Included in key areas is standby
equipment for use to correct failures quickly.

     Levels of BOD loss have been reduced from the 9072 kg per
day range (20,000 Ib/day) of 1971 to less than 454 kg per day
(1000 Ib/day) as a monthly average for 1975.  The daily maximum
of 1814 kg (4000 Ib) had not been exceeded in any mill-operating
day during 1975.

     This report was submitted in fulfillment of Grant Number
S-800520 under (partial) sponsorship of the Office of Research
and Development, U.S. Environmental Protection Agency.  This
report covers the period from July 19, 1972, through February 2,
1976.  Progress will be reported annually for an additional
five-year period.
                               IV

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                          CONTENTS
Foreword	iii
Abstract	iv
Figures	vi
Tables	vii
Abbreviations and Symbols  	  viii
Acknowledgment 	  ix

   1.  Introduction  	 1
   2.  Conclusions 	 3
   3.  Recommendations	5
   4.  Materials and Methods 	 6
          Process description  	 6
          Process water system closure 	 9
          Mill system water recycling	26
          Internal water monitoring and alarm system .   .  . .28
          Reverse osmosis system	31
   5.  Operating Experience	42
          In-plant environmental effects of mill water
             system closure  .	42
          Process water system additives	43
          Process water system ash buildup	44
          Reverse osmosis plant operating philosophy .   .  . .46
          Reverse osmosis module fiberglass membrane
             support tube failure	48
          Reverse osmosis membrane fouling	55
          Reverse osmosis pump and pump seal problems   .  . .58
   6.  Results and Discussion	60
          Resume of mill operating experience	60
          Medium strength characteristics and
             conversion behavior	66
          Economic evaluation of reverse osmosis vs.
             evaporation	68

References	71
Appendices

   A.  Analytical and test procedures and equations  ...  .72
   B.  Institute of Paper Chemistry summary on medium
          quality	76
   C.  Project visitors	79

Glossary	82
                              v

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                            FIGURES

Number                                                      Page
  1   Mill process	7
  2   Pulp mill—combustion plant liquor flow	8
  3   Historical mill discharge performance	10
  4   Mill discharge stream—1971	11
  5   Mill discharge stream—1975	12
  6   Paper machine floor collection system—1971	14
  7   Paper machine floor collection system—1975	18
  8   Pulp mill floor collection system—1971	20
  9   Pulp mill floor collection system—1975	21
 10   Mill effluent sources	25
 11   Process water reuse system 	 27
 12   Paper machine effluent system—alarm points	30
 13   Reverse osmosis plant interface	34
 14   Reverse osmosis plant	35
 15   Pump assembly rack	36
 16   Module rack	38
 17   Reverse osmosis flow diagram 	 39
 18   Reverse osmosis plant control	41
 19   Grit removal system	45
 20   Flux performance comparison	49
 21   Cleaned module flux data	. .  . 50
 22   Photomicrographs—new and aged tubes	52
 23   "Original" vs.  "improved" module failure experience.  . 54
 24   Relationship of percent dissolved solids 	 61
 25   Paper machine productivity 	 62
 26   Total mill cost factors	64
                              VI

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                            TABLES


Number                                                      Page

  1   Mill Discharge Streams—1971 	 13

  2   Mill Discharge Streams—1975 	 13

  3   Inventory of Potential Problems as of 1971 and
        Disposition as of 1975—East Machine Room
        Discharge	15

  4   Inventory of Potential Problems as of 1971 and
        Disposition as of 1975—West Machine Room
        Discharge	16

  5   Inventory of Potential Problems as of 1971 and
        Disposition as of 1975—Dilution Streams 	 17

  6   Inventory of Potential Problems as of 1971 and
        Disposition as of 1975—Pulp Mill Discharge	22

  7   Inventory of Potential Problems as of 1971 and
        Disposition as of 1975—Recovery Plant Area	23

  8   Inventory of Potential Problems as of 1971 and
        Disposition as of 1975—Wood Room Discharge	23

  9   Inventory of Potential Problems as of 1971 and
        Disposition as of 1975—Tank Storage Area	24

 10   Total Reverse Osmosis Plant Average Operating
        Parameters	61

 11   Strength Comparison—Open to Closed System	67
                             VII

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                LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS

BOD 5
Btu
E.D.T.A. Na4
gfd
gpm
HP
MGD
NSSC
PH
psi
#

SYMBOLS

HC1
Mg
Na2C03
Na2S04
five-day biochemical oxygen demand
British thermal unit
sodium salt of ethylenediaminetetra acetic acid
flux units—gallons per ft2-day
gallons per minute
horsepower, electrical
million gallons per day
Neutral Sulfite SemiChemical
hydrogen ion concentration, logarithmic form
measure of pressure—pounds per square inch
pounds, mass
hydrochloric acid
magnesium
sodium carbonate
sodium sulfate
                              viii

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                         ACKNOWLEDGMENTS
     This project was performed under the direction of
Mr. Ralph H. Scott, Chief, Wood Products Staff, U. S. Environ-
mental Protection Agency, federal Project Officer.  Project
Director for Green Bay Packaging was Mr. William R. Nelson;
Project Manager was Mr. Gerald 0. Walraven.  Other Green Bay
Packaging personnel participating in the project were Messrs.
David C. Morris  (now with Weyerhaeuser Co.), Scott Brown (now
with Simons-Eastern Co.), and Peter E. DeRossi, Chemical
Engineers; Messrs. Orv Rautmann and Dave Meverden, Chemists;
Mr. Richard Wisneski, Engineering Technician; Mr. Frank Piechota,
Process Technician; and Mrs. Kathy Pitts, Secretary.

     The close cooperation and assistance of Universal Oil
Products, Fluid Systems Division (previously Fluid Sciences
Division), is gratefully acknowledged.  Key personnel were
Messrs. Kenneth E. Anderson, Richard A. Walker, Richard B.
Hartupee, and Dr. Jay Sobel of Corporate Research.

     The long-standing and excellent support of the staff of the
Institute of Paper Chemistry is also acknowledged.

     The privilege to present project interim reports through
both the Technical Association of the Pulp and Paper Industry
and American Institute of Chemical Engineers, Environmental
Division, is gratefully acknowledged.
                                IX

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                            SECTION 1

                          INTRODUCTION


     Green Bay Packaging Inc. operates a pulp and paperboard mill
adjacent to the Fox River in Green Bay, Wisconsin.  The mill pro-
duces approximately 270 metric tons per day of corrugating medium
from a combination of virgin mixed hardwood, neutral sulfite
semichemical  (NSSC) pulp, and recycled corrugated box plant waste
fiber.

     The organic products of reaction  (pulping liquors) from the
sodium NSSC pulping operations are separated at their highest
concentration from the virgin pulp fibers produced.  The strong
pulping liquors are screened to minimize the loss of usable
fiber, inventoried, and eventually burned in a Dorr-Oliver fluid
bed combustion plant to destroy the organics and produce a mar-
ketable inorganic ash.  The residual  (approximately 25%) pulping
liquor organics remaining with the pulp fibers subsequently leach
into the process water, which conveys the fibers through the'con-
ventional fiber processing and papermaking process.

     The corrugated box plant wastes are returned to the paper-
board mill process for reuse by repulping in excess paper machine
process water at elevated temperature.  Residual soluble mate-
rials become redissolved in the process water as the waste fibers
are separated and resuspended.  The resulting recycled fiber is
eventually combined with the NSSC pulp fiber and passed through
the normal processing stages, finally being made into corrugating
medium at the paper machine.

     Earlier construction and operation of the fluid bed combus-
tion plant had satisfactorily solved the strong NSSC pulping
liquor waste problem.  It has been necessary to address the
problem of residual pollutional losses as they appear in both
variable and constant excess process water losses containing low
concentrations of solubles from both the virgin NSSC and the
recycled pulping and papermaking operations.

     The efforts of the company to further reduce the pollutional
effect of the mill discharge to the Fox River have been directed
primarily at identifying, in both quality and quantity parame-
ters, the many uses of the process water system and to identify
methods of collection and control, reuse, or treatment to prevent
the losses of such excess process waters to the river.

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      Encouraging progress had been made in the reuse of excess
 process waters  at the Green Bay mill concurrent with a pilot
 plant evaluation project on the reverse osmosis process for con-
 centrating  such excess process waters under a Demonstration Grant
 from  the  Office of Research and Monitoring of the U. S. Environ-
 mental Protection Agency.  The information generated at that time
 has been  reported in Water Pollution Control Research Series
 12040 FUB,  published by the U. S. Environmental Protection Agency
 in January,  1972.  The results achieved during that time are the
 basis for the project here reported.

      In June, 1972, a Research, Development, and Demonstration
 Grant offer was made to Green Bay Packaging Inc. in support of a
 mill  scale,  multifaceted effort to demonstrate a "Closed Process
 Water Loop  in NSSC Corrugating Medium Manufacture."  The project
 objective was to accomplish the maximum closure of water use loop
 in an integrated pulp and paperboard mill by recycling contami-
 nated process waters for direct reuse; by providing a protective
 collection  and  surge system for such excess surge volumes as
 might occur during both normal operations and process upset con-
 ditions;  by providing a continuous system of loss monitoring
 capability  to support operator decisions; and by providing a
 reverse osmosis plant of appropriate capacity to separate pollu-
 tional constituents from such excess volumes as might occur,
 prior to  their  discharge from the mill, while recycling permeate
 so produced to  the maximum practical extent.

      A secondary objective of the project was to demonstrate the
 results of  paperboard making operations under such high water
 reuse conditions and to report useful techniques of operating.
 The project was visualized as a one-year operation under maximum
 closure conditions to fully demonstrate the effects on production
 efficiency,  maintenance, product quality, and mill pollutipnal
 control.  A further objective of the project was to report the
 operating performance of the reverse osmosis facility over one
 year  of continuous operation, together with capital and operating
 costs of  the reverse osmosis facility.

      Although the project completion was anticipated in 32
 months, actual  completion has required 48 months due to time con-
 suming problem  analysis and correction in certain areas.  In
 general,  the time extensions were required to allow for exper-
 ience in  proprietary reverse osmosis equipment corrections, which
 in turn allowed for a more comprehensive evaluation of the over-
 all system performance.  The application of membrane technology
 in this instance is a direct substitution for conventional ther-
mal evaporation procedures.  In addition, the project objectives
present an opportunity to evaluate membrane separation perfor-
mance, as well  as a cost competitive technology, in comparison
with water removal operations of another form.

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                            SECTION 2

                           CONCLUSIONS
     Intensive recycling to minimize system losses has proven to
be the simplest and best course for our mill.   For three years,
the program to entrap, contain, and reuse water has proven suc-
cessful, as demonstrated by continued low losses while maintain-
ing production of a quality corrugating medium.  This approach
can apply generally, but even a simple change  in equipment—batch
to continuous digesters, screw presses to washers—may change the
water balance to preclude complete recycling,  through either cost
or physical impracticability.

     All constituents of a closed process water system tend to
increase in concentration to a new equilibrium, depending on
system conditions.   Calcium can reach a concentration where
objectionable scale will form in the process water or liquor
systems.  Sodium chloride, at increased concentrations, can
accelerate corrosion to the point where replacement materials of
construction are required, or it may interfere with a liquor
burning operation.   The modifications necessary for recycling
will necessarily be highly dependent on the existing plant and
process configuration.  An option of excess contaminated process
water collection, containment, and reuse open  to one plant may
not be a valid option for another.

     A small commercial reverse osmosis plant  has been able, on
demand, to maintain the reuse system volume within the limita-
tions of the available surge storage.  Although most reverse
osmosis operating problems have been solved, flux rates are
somewhat lower than had been predicted.  The actual operating
flux was 3.02 liters per square meter-hr (5.13 gal/ft^-day)
compared to the predicted flux of 3.94 liters  per square meter-hr
(6.68 gal/ft2-day).

     The life expectancy of the reverse osmosis module hardware
has been greatly improved through the efforts  of our supplier.
The project objective to identify module and membrane life
expectancy has not yet been realized.  The substitution of
reverse osmosis for conventional steam evaporation has been
successfully demonstrated.

     The low energy need for water removal from the process water
system has been offset by a higher capital cost for equipment.

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The relative economics prevailing at a given plant site will
determine whether membrane separation can offer advantages over
thermal evaporation.

     The large number of process modules necessary to build
reverse osmosis capacity presents serious problems to the appli-
cation of membrane technology to high volume, continuous duty
applications.  The experience of this project suggests continued
efforts be directed towards improving reliability of reverse
osmosis support structures and their associated equipment.

     The issue of trace contamination in tightly closed mill
water reuse systems deserves further attention.  Relatively rapid
changes in unexplained membrane fouling and the forms of fouling
experienced suggest that transient contaminants can seriously
affect the overall performance (and costs)  of a reverse osmosis
operation processing internal plant reuse waters.

     The project experience demonstrates the ability to recycle
process waters in the Green Bay Packaging mill without serious
detrimental effects on-production or product quality.  Changes in
raw materials, such as a high calcium water supply or inputs of
higher amounts of sodium chloride in cooking chemicals, will
create new equilibrium conditions in a closed system.  This con-
clusion only applies to the solubles present in this water reuse
system.  Application to another system must be predicated on
pilot experience on the reuse stream existing in that system.
Therefore, it should not be presumed that our experience is di-
rectly applicable to all unbleached board mills or even those
producing the same grade of NSSC corrugating medium because of
the vast differences in the raw materials used and the construc-
tion and age of many of these facilities.

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                            SECTION 3

                         RECOMMENDATIONS
     To become more economically attractive, vendors of reverse
osmosis equipment should produce membranes both capable of
higher flux rates and functional over wider ranges of pH and
temperature.  These advances in membrane technology would lead to
reduced capital costs for equipment and lower plant operating
costs, hopefully to a point where much broader application will
be realized.  Also, even though much progress has been made in
membrane support structures, there is still a need to improve
reliability and increase module life by improving the chemical
resistance of the materials presently used.  Module maintenance
and replacement costs, although not yet available from our
project data, will represent a large part of overall operating
costs.

     The causes and mechanisms of membrane fouling are not well
understood.  Additional efforts are needed to develop more under-
standing of fouling and methods of prevention and effective,
rapid cleaning.

     Development of better, higher volume high pressure pumps is
needed for all applications, particularly for feed streams which
act chemically to deteriorate existing industrial materials of
pump construction.

     When planning new installations or expanding old ones, more
consideration should be given to higher consistency pulp pro-
cessing methods.  The costs and advantages of maintaining a
balanced water system with internal disposal of pollutants should
be weighed against existing conventional systems, typically
utilizing end-of-the-line treatment systems.

     The corrosion problems associated with tightly closed water
reuse systems, inherently more severe because of increased tem-
peratures and electromotive activity, should be addressed by
basic equipment manufacturers and process design engineers.
Improved chemical resistance of all materials exposed to recycled
process water is a necessary objective to improve system reli-
ability and to reduce maintenance and operating costs.

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                            SECTION 4

                      MATERIALS AND METHODS
 PROCESS  DESCRIPTION

      The mill  produces  272 metric tons  (300 short tons) per day
 of  corrugating medium from NSSC pulp with mixed hardwoods and
 from recycled  box  plant clippings.  Figure 1 shows the mill pro-
 cess.  Four  rotary digesters produce about 181 metric tons  (200
 short tons)  per  day  of  pulp using a vapor phase cook.  Paper
 machine  process  water is added to the chips during the blow-down
 period to  aid  in the recovery of spent  liquor.  Partially pulped
 chips leave  the  screw presses at about  55% solids.  Paper machine
 process  water  is used for washing in the presses.  This process
 water is also  used to dilute the pressed chips to 26% consistency
 for primary  refining.   Secondary fiber, slurried in process
 water, is  added  to the  pulp prior to finish refining.  Further
 dilution to  headbox  consistencies with  paper machine process
 water precedes both  a coarse cleaner and a two-stage final cen-
 trifugal cleaning  system before the paper machine.

      Figure  2  shows  a more detailed layout of the process streams
 in  the pulp  mill,  as well as those going to the fluidized bed
 reactor  liquor system.  In the pulp mill, liquor is separated
 from the cooked  chips by two screw presses, combined with
 digester wash  and  blow  liquor, and screened to reclaim usable
 fiber.

     The screened  liquor, containing about 18% dissolved solids
 and  8.4  grams  per  liter (70 lb/1000 gal) of very fine suspended
 solids,  is stored  in a  227.1-cubic meter  (60,000-gal) insulated
 tank before  going  to the evaporators.   The smaller portion is fed
 to the Aqua-Chem spray-film evaporators and concentrated to about
 25%  solids.  The evaporated liquor can  be stored in either of two
 large insulated  tanks.  The smaller of  the two is the normal pro-
 cess storage and can hold a maximum of  557.7 cubic meters
 (150,000 gal).   The  other tank is used  for long-term storage for
 reactor  shutdowns  and can store up to 946.2 additional cubic
meters (250,000  gal).   The combined liquor storage will allow for
 a reactor shutdown of as long as ten days.  The normal turnaround
 time for reactor shutdown, cleanout, and repairs is about five
days.

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                  GASES - WATER - CO,
     SALT  CAKE
   32  TONS/DAY
     STEAM
      WOOD
  250  TONS/DAY

   CHEMICALS
 SODIUM SULFITE
  30 TONS/DAY

SODIUM CARBONATE
   8 TONS/DAY
 FLUIDIZED
BED REACTOR
                                                               CENTRIFUGAL
                                                                CLEANERS
                                                        CORRUGATING
                                                           MEDIUM
                                                       300  TONS/DAY
PRIMARY
REFINERS
                                FINISHING
                                 REFINER
                               CORRUGATING
                                 WASTE
                                 FIBER
                              100 TONS/DAY
                                                        REPULPER
                                                    DILUTION
                                                                                    PROCESS
                                                                                    WATER
                                 Figure 1.  Mill process.

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oo
     CLARIFIED
     WHITE WATER
     R-0  CONCENTRATE
                             PULP  MILL  WASH
                             DILUTION  TANK
                              I
                           DIGESTERS
       LIQUOR  RETURN
                  TANK
                  CHEMICAL
                  MIXING TANK
 SCREW
PRESSES
     (HL)  HIGH LEVEL  ALARM
                                     FLUIDIZED
                                       BED
                                     REACTOR
                         PULP MILL
                         WASTE  LIQUOR
                         STORAGE TANK
                EMERGENCY
               WASTE LIQUOR
               STORAGE  TANK
                                          EVAPORATED
                                            WASTE
                                            LIQUOR
                                           STORAGE
                                            TANK
                       Figure  2.   Pulp mill—combustion plant liquor flow,

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     Pulp mill  liquor  is  combined with the 25%  liquor,  and the
mixture  is  fed  to the  Venturi scrubber/evaporator and concen-
trated to 43% by the reactor hot gas stream,  A portion of the
43%  liquor  is fed to the  reactor as  fuel.   The  ratio of 18% and
25%  liquor  is adjusted for solids and water inventory control in
the  reactor Venturi loop.   Additional information on the Dorr-
Oliver Fluidized Bed Reactor system  can be found in the
August 17,  1970, issue of Paper  Trade Journal.(1)

PROCESS  WATER SYSTEM CLOSURE

     Much progress has been made since 1971 in  reducing BOD dis-
charge from the mill by a series of  steps  leading to an essen-
tially closed process  water reuse system (Figure 3).  Levels have
been reduced from the  44,091 kilograms per day  (20,000  Ib/day)
range  in early  1971 to less than 2200 kilograms per day
 (1000  Ib/day)—monthly average—for  1976.   The  total mill BOD
generated approximates 99,000 kilograms per day (45,000 Ib/day).
Note also the progress in reducing daily maxima so that 8800
kilograms per day (4000 Ib/day)  has  not been exceeded in any mill
operating day in the last year.

     Figures 4  and 5 are  averages of the discharge streams from
the  operating segment  of  the mill for 1971 and  1975,  respec-
tively.   Keys for the  losses for each stream are in Tables 1 and
2.   A  major step had already been accomplished  by the spring of
1971,  with  process water  successfully replacing fresh water on
most of  the paper machine showers.   Table  1 indicates the magni-
tude of  the losses that still existed in 1971 after the shower
conversion.  That year, the evolution of a closed process water
system started  in earnest with the preparation  of an inventory of
discharge streams according to priorities.  The improvements ob-
tained from 1971 to 1975  are observed by comparing the  differ-
ences  in each outfall  and the total  mill discharge in Table 2
with those  of Table 1.

     Figure 6,  the paper  machine basement  trench system diagram
in 1971, is an  example of the type of inventory for losses which
proved extremely useful in conquering the  problems that existed
at a given  outfall.  The  steps taken to eliminate losses and re-
vise the paper  machine system are indicated in  Tables 3, 4, and 5.
When completely revised, the paper machine  water collection
system appeared as is  shown in Figure 7.

     The highest priority  was assigned to  those contributions
whose  elimination was necessary  to reach 1973 permit limits.
These  included  pit and  tank overflows and  gutter or floor drain
flows  that could be recycled by  the  addition of more pumps and
tankage.  Uncontaminated cooling water was  repiped to bypass the
recycle  loop (see Table 5,  Inventory of Dilution Streams).  Addi-
tional screened process water washup hoses  were added at the
paper machine so that city water is  used only at the final step

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   26,000


   24,000

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    MILL DISCHARGE
FLOW      -   1.80 MGD
TOT.  SO LI D S - 2847 7 */ DAY
SUS. SOLIDS-  II22*/DAY
BOD 5      -  59 3 2*/ DAY
                                                TO  RIVER
    FLUIDIZED BED
       REACTOR
    RIVER  WATER IN
FLOW       -   1.20 MGD
TOT. SOLIDS - 3450?VDAY
SUS. SOLIDS -   I90*/DAY
BODs       -   115V DAY
                                                                 Q-SEE TABLE-1
                                                             BOILER  FLYASH
                                                                POND
                                                                 CITY WATER  IN
                                                             FLOW
                                                             TOT. SOLIDS-
                                                             SUS. SOLIDS -
                                                             BOD5
                                                                             0.7  MGD
                                                                           75O*/DAY
                                                                              O^DAY
                                                                              0*/DAY
                                                                           1
                                                           CORRUGATED
                                                             WASTE
                                                            REPULPER
                                                               MACHINE  ROOM

                                                                              1
                      Figure 4.  Mill discharge  stream—1971.

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          MILL  DISCHARGED
       FLOW       -   Tio^MGD
       TOT, SOLIDS-  7343*/DAY
       SUS. SOLIDS-   420*/DAY
       BOD 5       -   I008#/DAY
          FLUIDIZED  BED
            REACTOR
N)
    RIVER  WATER  IN
FLOW      -    1,20 MOD
TOT. SOLIDS -  2968%DAY
SUS. SOLIDS -   281*/DAY
BODs      -    83*/DAY
                                                                   Q- SEE TABLE-2
BOILER  FLYASH
    POND
ROOM

*AGE
PULP MILL

CITY WATER IN
FLOW - 0.5 MGD
TOT. SOLIDS- 700 */ DAY
SUS. SOLIDS- 0*/DAY
BOD 5 - 0*V DAY

CORRUGATED
WASTE
REPULPER
L- 1
1
1
1
1
1
1
1
1
1 MACHINE ROOM
1
                                                    1
                  1
                            Figure 5.  Mill discharge stream--1975.

-------
TABLE 1.  MILL DISCHARGE  STREAMS—1971
           (Key for Figure 4)




1.

' 2.

3.
4.
5.
6.

7.



Stream
East machine
room
West machine
room
Pulp mill
Tanks
Wood room
Fluidized bed
reactor
Total mill
discharge
Total
Flow solids
(MGD) (f/day)

1.070 11,887

0.029 2,100
0.287 2,100
0.047 9,929
0.040 393

0.327 2,031

1.800 28,477
Total
suspended
solids
(#/day)

377

137
184
329
45

50

1,122

BOD5
(i/day)

2,350

490
327
2,400
0

365

5,932



TABLE 2.

MILL DISCHARGE STREAMS — 1975
(Key for Figure 5)







1.

2.

3.
4.
5.
6.

7.




Stream
East machine
room
West machine
room
Pulp mill
Tanks
Wood room
Fluidized bed
reactor
Total mill
discharge

Total
Flow solids
(MGD) (#/day)

1.140 5,637

(Discontinued)
0.250 610
0.001 430
0.040 108

0.170 558

1.600 7,343
Total
suspended
solids
(#/day)

125


281
14
0

0

420


BODs
(tt/day)

832


19
107
0

50

1,008
                   13

-------
         REPULPER
                   TO  REUSE
        KEY  REFER TO TABLES 3,4,5

        NUMBER - POTENTIAL  LOSS

      H> LETTER-DILUTION
                            PROCESS WATER
                            COLLECTION  PIT
                               FINISHING
                               REFINER
WEST MACHINE
ROOM DISCHARGE
OQO
                                               VACUUM  PUMPS
                                MAIN  EFFLUENT  LINE
 EAST  MACHINE
ROOM  DISCHARGE
            Figure  6.   Paper machine  floor collection  system—1971.

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      TABLE 3.   INVENTORY OF POTENTIAL PROBLEMS  AS OF 1971
     AND DISPOSITION  AS  OF  1975—EAST  MACHINE ROOM DISCHARGE

                          (In Order  of  Priority)


	(Code  for  Machine Room Discharges, See Figures  6 and 7)	

            1971 - Problem                                1975 - Status

Number 1 Priority:  Urgent—elimination necessary to meet  1973 limits

1) Seal pit and paper machine process         Combined  pits; installed larger pumps;
   water collection pit overflow; shut-       installed spare pump;  installed high
   down and startup surges or pump            level alarm
   failure
     Amount:   3000 gal
     Frequency:  once/day

2) Losses from paper machine gutters          All losses directed to process  water
   and floor  drains from normal seepage       pit by new piping
   and washup
     Amount:   2-5 gal/min

3) Periodic entrainment of process water      Installed conductivity alarm and  manual
   in Centri-Cleaner vacuum pump seal         vacuum breaker; modified vacuum pump
   water                ,                     seal water system
     Amount:   5 gal/min
     Frequency:  30 min/wk

Number 2 Priority:  Needed to ensure stable operation and  better closure

   None in this category

Number 3 Priority:  May be postponed until after  1973—more information is required
4) Overflow of Centri-Cleaner reject          Discharges to enclosed sewer and  is
   tank; shutdowns and failure of pump        recycled  with sump pump
     Amount:   50 gal
     Frequency:  each shutdown,
                2-3 times/wk

5) Couch and wet press vacuum pump    •       Unresolved
   carryover
     Amount:   3-5 gal process water/min

6) Trap dumping Magna Cleaner finishing       Now dumps to closed sewer and is
   refiner                                   recycled  by  sump pump
     Amount:   20 gal process water
     Frequency:  once each.8 hr

7) Trap dumping Magna Cleaner secondary       Now dumps to closed sewer and is
   Centri-Cleaner system                      recycled  by  sump pump
     Amount:   20 gal process water
     Frequency:  once each hr

8) Overflow from overfilling paper            Now is in closed sewer area; stock is
   machine stock storage chests               manually  washed back to sump pump for
     Amount:   600-1000 gal process water      recycle
              and fiber
     Frequency:  once/mo
Number 4 Priority:  Insignificant or poorly defined

9) Paper machine area pumps and side          Most leaks are located in area of
   agitator seal leaks                        enclosed  sewer and are recycled with
     Amount:   small but continuous            sump pump

10) Seepage from area under paper             Unresolved
    machine wet presses
      Amount:  small but continuous,
              some fiber loss
                                        15

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      TABLE 4.  INVENTORY OF POTENTIAL PROBLEMS AS OF 1971
     AND DISPOSITION AS OF 1975—WEST MACHINE ROOM DISCHARGE
                     (In Order of Priority)

	(Code for Machine Room Discharges, See Figures 6 and 7)	

        1971 - Problem                     1975 - Status

West sump pump is not used presently.

Number 1 Priority:  Urgent—elimination necessary to meet 1973
                    limits

12) Kraft clippings repulper       Installed bar screen for large
    sump pump failure; me-         junk; can now be diverted to
    chanical or plugged with       process water pit for complete
    large junk                     pump failure
      Amount:  5000 gal
      Frequency:  once/two mo

13) Losses of process water        Eliminated at end of pilot
    and fiber from pilot DSM       work
    screen for reverse osmosis
    pilot work; coarse fraction
    only
      Amount:  5 gal/min

14) DSM screen supply tank         Installed interlock system
    overflow                       high level; installed larger
      Amount:  2000-3000 gal       pump to DSM screen; added one
      Frequency:  twice/mo         screen section to DSM screen

Number 2 Priority:  Needed to ensure stable operation and better
                    closure

    None in this category

Number 3 Priority:  May be postponed until after 1973—more
                    information is required

    None in this category

Number 4 Priority:  Insignificant or poorly defined

15) DSM supply tank area;          Added new sewer trench to
    pumps and agitator seal        discharge to recycle system
    leaks
      Amount:  small but
               continuous
                                16

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      TABLE 5.  INVENTORY OF POTENTIAL PROBLEMS AS OF 1971
                   AND DISPOSITION AS OF 1975

         Inventory of Dilution Streams Entering Process

                        East Machine Room

           (Code for East Machine Room Dilution Streams)
                      (See Figures 6 and 7)
        1971 - Problem
        1975 - Status
A) Air conditioner cooling
   water, three units
     Amount:  25 gal/min

B) Oil coolers and air
   compressor cooling water
     Amount:  17 gal/min

C) Washup hoses, used on
   paper breaks
     Amount:  1000 gal/day
D) Centri-Cleaner vacuum pump
   seal water
     Amount:  9 gal/min
Piped out of closed system
Piped out of closed system
Two hoses connected to clari-
fied process water; city water
hose used only for final
washing
  Amount:  300 gal/day

Piped out of closed system but
alarmed for process water en-
trainment; see Item 3—East
Machine Room Discharge
                        West Machine Room
   None in this category
                            Pulp Mill

    (Code for Pulp Mill Dilution Streams, See Figures 8 and 9)
A) Oil coolers
     Amount:  10 gal/min

B) Digester blow line sample
   condenser
     Amount:  8 gal/min

C) Pulp mill testing station
   sinks
     Amount:  2 gal/min
Rerouted directly to main
effluent line

Rerouted directly to main
effluent line
Rerouted to sanitary sewer
                               17

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00
 WEST  MACHINE
ROOM  DISCHARGE
 (DISCONTINUED)
                                                               KEY  -REFER TO TABLES 3,4,5

                                                            (H)  NUMBER - POTENTIAL  LOSS

                                                            ffft  LETTER - DILUTION
                                       PROCESS  WATER
                                      COLLECTION  PIT
                                              i
                                     bOO
                                              CHESTS
                                          FINISHING
                                          REFINER
     \ w Ah
000
                                                          VACUUM
                                           MAIN  EFFLUENT LINE
            PUMPS
                                                                                  EAST MACHINE
                                                                                 ROOM  DISCHARGE
                       Figure  7.   Paper machine floor collection system—1975.

-------
in washup.  City water, in small amounts, is still used on the
cut squirts due to their tiny nozzles and at other critical
points, such as the breast roll shower and suction roll box
seals.

     The same type of approach was used in the other operating
areas of the mill.  Figures 8 and 9 and Tables 5 and 6 are the
result of a similar study made for the pulp mill.  Tables 7, 8,
and 9 indicate the problems and changes made in the reactor area,
wood room, and tank storage area, respectively.  No diagrams are
included, but most items are self-explanatory.

     In a lower priority category were steps that were needed to
ensure stable operation and better closure.  These included such
steps as collection of evaporator cleanout streams and steam
tracing and insulating of storage tank transfer lines formerly
dumped to avoid freezing.

     In a third priority category were items which could be
deferred until after 1973 or which required more information.
Some of these are now being evaluated, for example, a cyclonic
mist separator on the couch vacuum pump.  Others are unresolved
at this time.  Some have been taken care of more recently,
including collection and recycling of both the acid scale removal
waste stream from the bimonthly cleaning of recovery plant piping
and the caustic from the evaporator demister pad wash.  An unre-
solved problem is the acid condensate from the evaporator, adding
22.7 kilograms per day  (50 Ib/day) of BOD to the effluent.
Another continuing problem is leaking of strong liquor from pump
and agitator packing in the storage tank area.

     The list of problems and solutions may not be complete, and
will not apply directly to other mills, but should convey that
reaching complete closure is an evolutionary process consisting
of a great many separate steps, requiring diligence in seeking
out and identifying even the minor contributions.  Figure 10
summarizes the mill effluent sources as they now exist.

     Although the total flow was reduced by only 11% since 1971,
the total suspended solids and BOD loads were reduced by 63% and
83%, respectively.  Most of the mill discharge is made up of
river water which receives no treatment other than coarse screen-
ing.  It is used, without recirculation, as seal water on vacuum
pumps, for evaporator cooling, and for wood slab washing.  The
remainder of the effluent is uncontaminated city water used for
cooling of air conditioners, air compressors, and oil coolers.

     Present losses are characterized either as routine during
stable operation or as upset losses.  The largest routine loss is
the mist of process water carried into the vacuum pump seal
water.  The upset losses arise during nonroutine conditions, such
                                19

-------
to
o
                            SCREW
                       SUMP  PRESSES
                                            REFINERS
                                         DDDQ
     SUMP
                                   HYDRASIEVE
       DO Din
                                              REFINERS
                                                    |
\5)
±
                                 KEY -REFER TO TABLES 5 and 6
                                 x
                                  NUMBER - POTENTIAL  LOSS

                                  LETTER-DILUTION
      RIVER
      WATER
      SCREEN
                         MAIN EFFLUENT  LINE
               Figure 8.  Pulp mill floor collection system—1971.

-------
N)
        SCREW
SUMP   PRESSES
                                                                                          TO
                                                                                        SANITARY
                                                                                         SEWER
                                                                       REFINERS  /
                                                   KEY  -REFER TO TABLES 5 and 61

                                                    NUMBER - POTENTIAL  LOSS

                                                    LETTER-DILUTION
          RIVER
          WATER
         SCREEN
                                       MAIN   EFFLUENT  LINE
                        Figure 9.  Pulp  mill floor collection system—1975.

-------
      TABLE 6.  INVENTORY OF POTENTIAL PROBLEMS AS OF 1971
         AND DISPOSITION AS OF 1975—PULP MILL DISCHARGE
                      (In Order of Priority)

        (Code for Pulp Mill Discharge, See Figures 8 and 9)
        1971 - Problem
                       1975 - Status
Number 1 Priority:
Urgent—elimination necessary to meet 1973
limits
1) Periodic overflow of press
   and digester process water
   wash tank
     Amount:  100-200 gpm
     Frequency:  5 min/wk

2) Weak liquor seepage in
   screen area from splashes
   and leaks; concentrated
   liquor
     Amount:  1/4 gpm,
              continuous

3) Screw press tank overflow
   from plugging with fiber
   and chips
     Amount:  25 gpm
     Frequency:  5 min,
                 twice/day

4) Overflow from pulp mill
   tank for fiber recovered
   from waste liquor
     Amount:  150 gal
     Frequency:  each mill
                 shutdown,
                 2-3 times/wk
               Control of makeup to tank
               improved; overflow to closed
               pulp mill liquor sump
               Directed to closed pulp mill
               liquor sump
               Directed to closed pulp mill
               liquor sump
               Directed to closed pulp mill
               liquor sump
Number 2 Priority:
Needed to ensure stable operation and better
closure
5) Dump of Hydrasieve effluent
   tank to clean out sand
     Amount:  100 gal/wk

6) Stock pump pit seepage
     Amount:  small but con-
              tinuous, stock and
              process water
               Directed to closed pulp mill
               liquor sump; installed contin-
               uous sand removal system

               Directed to closed pulp mill
               liquor sump
                               22

-------
      TABLE  7.    INVENTORY  OF  POTENTIAL PROBLEMS AS  OF  1971

          AND DISPOSITION AS OF 1975—RECOVERY  PLANT AREA
                         (In Order of  Priority)
                                                           •**
	(Not Diagramed)	

           1971 - Problem                             1975 - Status

Number 2  Priority:  Needed to ensure stable operation and better closure

1) Dumping of  Merco motor driven filter      Installed  small collection  tank and
   sludge                                  pump to divert to unclarified process
     Amount:   2 gal 40% liquor               water surge tank
     Frequency:  once/hr

2) Flushing of gorator pump for repairs      Flushes to recovery plant collection
     Amount:   100 gal                       tank
     Frequency:  once/120 days

3) Evaporator  cleaning with water and        Pump directly to unclarified process
   NaOH                                    water surge tank or weak liquor tank
     Amount:   300-500 gal
     Frequency:  once/wk

Number 3  Priority:  May be postponed until after 1973—more information is required

4) Acid used to remove scale from            Pumped to  recovery plant collection
   liquor feeding lines                     tank                            '
     Amount:   400 gal
     Frequency:  once/2 mo

5) Caustic wash for evaporator demister      Pumped to  recovery plant collection
   pads       ,                             tank
     Amount:   250 gal
     Frequency:  once/wk

6) Acid condensate from evaporators          Unresolved; evaporator usage is about
     Amount:   20 gpm                        1/3 of what it was in 1971—501
     Frequency:  150-200# BOD/day            BOD/day
      TABLE  8.    INVENTORY  OF  POTENTIAL PROBLEMS AS  OF  1971
          AND DISPOSITION AS OF 1975—WOOD  ROOM DISCHARGE
                         (In Order of  Priority)

	(Not Diagramed)	

           1971 - Problem                              1975 - Status

Number 3 Priority:  May be postponed until  after 1973—more information is required

1)  Losses  of fiber, bark,  and small          Sweco screen and sump added to remove
   chips                                    debris
                                      23

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       TABLE  9.   INVENTORY  OF POTENTIAL PROBLEMS  AS  OF  1971
            AND DISPOSITION  AS OF 1975—TANK  STORAGE  AREA
                           (In Order of  Priority)
                                (Not  Diagramed)
            1971 -  Problem
                                                      1975 - Status
Number 1 Priority:

1)
                 Urgent—elimination necessary to meet 1973 limits
Seal pit and paper machine process
water collection pit overflow; shut-
down and startup surges  or pump
failure
  Amount:  3000 gal
  Frequency:  once/day
                                             Combined pits; installed larger pumps;
                                             installed spare pump; installed high
                                             level alarm
2)
                                          All losses directed to process water
                                          pit by new piping
3)
    Losses from paper machine gutters
    and  floor drains from normal seepage
    and  washup
     Amount:  2-5 gal/min

    Periodic entrainment of process  water
    in Centri-Cleaner vacuum pump seal
    water
     Amount:  5 gal/min
     Frequency:  30 min/wk

Number  2 Priority:  Needed to ensure stable operation and better closure

    None in this category
Number  3 Priority:  May be postponed until after 1973—more information is required
                                          Installed conductivity alarm  and manual
                                          vacuum breaker;  modified  vacuum pump
                                          seal water system
4)
5)
6)
Overflow of Centri-Cleaner reject
tank; shutdowns and  failure of pump
  Amount:  50 gal
  Frequency:  each shutdown,
              2-3  times/wk

Couch and wet press  vacuum pump
carryover
  Amount:  3-5 gal process water/min
                                             Discharges to enclosed sewer and is
                                             recycled with sump pump
                                             Unresolved
                                          Now dumps to closed sewer and is
                                          recycled by sump pump
   Trap dumping Magna Cleaner  finishing
   refiner
     Amount:  20 gal process water
     Frequency:  once each.8 hr

7) Trap dumping Magna Cleaner  secondary
   Centri-Cleaner system
     Amount:  20 gal process water
     Frequency:  once each hr

8) Overflow from overfilling paper
   machine stock storage chests
     Amount:  600-1000 gal process water
              and fiber
     Frequency:  once/mo
Number 4 Priority:   Insignificant or poorly defined

9) Paper machine area pumps and side          Most leaks are located in area of
   agitator seal leaks                       enclosed sewer and are recycled with
     Amount:  small but continuous            sump pump

10)  Seepage from area under paper             Unresolved
    machine wet presses
      Amount:   small but continuous,
               some fiber loss
                                             Now dumps to closed  sewer and  is
                                             recycled by sump pump
                                             Now is in closed sewer  area;  stock  is
                                             manually washed back to sump  pump for
                                             recycle
                                        24

-------
       RIVER
       WATER
RIVER
WATER
SCREEN
to
                                       WET  PRESS
                                      VACUUM  PUMP
                                       SEAL  WATER
                       REVERSE
                       OSMOSIS
                       PERMEATE
       CITY WATER
       FOR  COOLING
 AIR CONDITIONERS
 OIL COOLERS
 AIR COMPRESSORS
COUCH  ROLL
VACUUM  PUMP
SEAL WATER
                                             WOOD  ROOM
                                              SLAB  WASH
                                               FILTRATE
                                            BOILER
                                            FLYASH
                                             POND
                                                       FLAT  BOX
                                                       VACUUM PUMP
                                                       SEAL  WATER
                                              PAPER MILL DISCHARGE
            fcl  CONDUCTIVITY
EVAPORATOR
 CONDENSER
   WATER
                                                              ACID
                                                          CONDENSATE
                                                                           COOLING
                                                                           WATER
                                                                      MAIN  EFFLUENT LINE
                               Figure  10.   Mill effluent sources.

-------
as shutdowns for machine clothing changes or failures in controls,
equipment, and/or human judgment.

MILL SYSTEM WATER RECYCLING

     The  fresh water input to the process system was reduced from
3.21 cubic meters per minute  (850 gpm) a few years ago to 0.491
cubic meters per minute  (130 gpm) today.  The 0.491 cubic meters
per minute of water that does enter the process water system is
either carried with the raw chips or is from certain small four-
drinier showers and many pump shaft seals.

     All  the excess water produced at the paper machine is
directed  to the main collecting point, which is the process water
collection pit  (Figure 11).  This pit also receives the water
from the  paper machine floor washup drains and the floor gutters
along the fourdrinier and wet presses.  The collected water from
the process water collection pit, containing about 2.16 grams of
suspended solids per liter  (18 lb/1000 gal), is pumped to our
unclarified process water surge tank and is then supplied for
direct reuse to the areas insensitive to suspended solids.  These
uses are  waste paper repulping, machine broke repulping, all
stock dilution, and cooking liquor makeup.

     The  excess unclarified process water not needed for the
above operations is metered, based on unclarified process water
surge tank level, into a large stream being used for corrugated
waste repulping.  This dilute stock is processed over a vacuum-
less thickener.  Due to the gentle driving force removing water
on the thickener, the thick mat containing long kraft fibers acts
as an excellent filter medium for the retention of fiber, and the
filtrate  contains only 0.66 grams of suspended solids per liter
(5.5 lb/1000 gal) with very little long fiber.  The excess por-
tion of this clarified filtrate is then pumped at a constant
nozzle pressure of 2.81 kilograms per square centimeter  (40 psi)
over a four-bank, 150-micron DSM slotted screen for removal of
any remaining long fiber down to 0.0096 grams per liter  (0.08 lb/
1000 gal).  The treated water will still contain from 0.24 to
0.60 grams per liter (2 to 5 lb/1000 gal) of extremely fine sus-
pended solids.  The clarified water is stored in our clarified
process water tank and is reused on all paper machine showers
except cut squirts, the breast roll shower, and the seal water
showers on the suction roll boxes.

     Process water showers were selected after extensive testing
of a variety of designs.  The Bird Aqua-Purge shower was selected
for its simplicity and absence of parts subject to deterioration.
A key element in the successful operation of these process water
showers is the completely closed design of tanks and other ele-
ments following the DSM screen cleaning step.  This assures the
absence of debris that might otherwise cause plugging.
                                26

-------
      CLARIFIED
      PROCESS
      WATER TANK
to
                                       FIBER TO PROCESS
                                                                                       FIBER
                                                                                     THICKENER
                                                                     FIBER  TO
                                                                      PROCESS
         DSM
         FILTRATE
         TANK
                 PAPER
                MACHINE
                SHOWERS
           PROCESS  WATER
           COLLECTION   PIT
VACUUM BOX
  SEAL  PIT
REVERSE
OSMOSIS
PLANT
T>
w
                                 CONCENTRATE
                                 TO PULP MILL WASH
                                 DILUTION  TANK
          PERMEATE  TO
       EAST  PAPER MILL DISCHARGE
       (fift HIGH  LEVEL  ALARM

       ^F> PUMP  FAILURE

k
.M*
M £
SUP
5CREEN
PLY
                                                                                           RECYCLED
                                                                                             FIBER
                                                                                           REPULPER
                                                                     UNCLARIFIED
                                                                     PROCESS WATER
                                                                     SURGE TANK
                                                                          HEAT
                                                                        RECOVERY
                                                                        SCRUBBER
                                                          REFINING
                                                          WATER SUPPLY
                                                          TANK
                                                                                             REFINERS
                                                                          TO
                                                                         BROKE
                                                                         PULPER
                                                                        DILUTION
                                                                                                       TO PROCESS
                                          UNCLARIFIED
                                          PROCESS WATER
                                          STORAGE TANK
                                    Figure  11.   Process  water reuse  system.

-------
     A third very large tank—946.2 cubic meters (250,000 gal)—
serves as long-term storage.  This tank, designated as the un-
clarified process water storage tank, is held at a constant level
by water flowing in a loop from the unclarified process water
surge tank and back to the same tank at equal rates.

     Two precautions are necessary in a closed water system.  The
first is to keep the process water hot; the second, to have no
dead storage areas where cooling can take place and sludge can
form.  An area that is cool and/or dead will promote aerobic or
anaerobic bacteria growth.

     If in the course of operating an excess of water occurs
either in the unclarified process water surge tank or clarified
process water tank, the flow in the loop from the unclarified
process water storage tank is lessened or stopped until the
excess is removed from the system and stored in the unclarified
process water storage tank.  Then the normal equal flow in and
out of this tank will resume.  Likewise, a deficiency in either
the clarified process water tank or unclarified process water
surge tank will cause an increase in the returning flow rate from
the unclarified process water storage tank until the need is
satisfied.

     Although there has been a substantial increase in wire pit
suspended solids (from 0.2% to 0.3% as a result of closure),
there has not been a loss of machine speed.  Higher process water
temperature—71°C  (160°F)—and higher average sheet moisture
(computer control)  have undoubtedly been compensating factors.
Furthermore, the increase in water extractables in the final
sheet—increased from 20 to 41 kilograms per metric ton  (40 to
180 Ib/ton) due to closure—has been accompanied by a reduction
in fiber content at the same basis weight and, presumably, a
corresponding reduction in drainage resistance.  No stiffness-
related strength loss is associated with this change in compo-
sition.

INTERNAL WATER MONITORING AND ALARM SYSTEM

     An important aspect of running a tightly closed mill is
knowing when and where process problems occur, as system upsets
and resulting spills remain a potential source of excessive dis-
charge from a normally tight system.  A good monitoring  system
is necessary to know as quickly as possible the location and  de-
gree of BOD and suspended solids losses.

     The monitoring system put into use at Green Bay Packaging
contains generally two types of sensors:  storage level  alarms
and effluent concentration measurement by conductivity.

     The monitoring and alarm system provides the following
information at a central location:


                               28

-------
      (1)  A continuous record of the total mill effluent
          dissolved solids level.

      (2)  A continuous monitoring of potentially high pollutant
          discharges at selected locations throughout the mill.
          Mill personnel are informed by an annunciating alarm
          panel of the upset conditions.

      (3)  A continuous record of each upset occurrence and its
          duration; also, "on time" event and duration of
          standby equipment, such as backup pumps.

      (4)  A continuous record of the dissolved solids concen-
          tration measured by each of the conductivity sensors.

      In addition, this system is flexible to revision and is a
source of dependable information which can be relied upon for
overall supervision of a closed mill water balance.

      It is worth noting that much work was done to determine the
relationship between conductivity and dissolved solids concen-
tration of the mill process water.  This was necessary as con-
ductivity measurement was to be the tool for the system monitor-
ing.  Once conductivity was selected as the means of system
monitoring, the number and locations of the sensors were deter-
mined .

      Four locations have been selected for the conductivity
sensors.  The sensors are presented in sequential order as they
occur in the mill effluent system.  The first sensor is on the
vacuum pump discharge from the centrifugal cleaners.  Although
this  discharge is normally fresh water, the vacuum seal can
break, allowing process water with 5% dissolved solids to be dis-
charged to the main clear water sewer in the mill.  The next
conductivity sensor is in the trench receiving the paper machine
vacuum pump discharge.  This flow is primarily river water; how-
ever, the main sewer trench also directs its flow past this
sensor so that upsets occurring in the mill basement can be de-
tected  (see Figure 12).  Another sensor is in the recovery plant
discharge leading to the main effluent line.  Ordinarily, this
stream consists of cooling water from the evaporator condensers;
however, an occasional strong liquor spill in the recovery plant
can reach this stream (see Figure 10, page 25).  Finally (on the
same  diagram), a conductivity sensor is at the flume.  Its pur-
pose  is to monitor total mill effluent concentration.  This
sensor provides information on the relative strength of the
effluent reaching the river.

      In addition to relative strengths of streams within the mill
system, liquid levels are monitored on five tanks and two sumps.
High  level alarms using conductance probes alert mill personnel
of impending problems prior to overflow.  Enough advance notice

                               29

-------
       REPULPER
        SUMP
TO REUSE
SUMP
 WEST MACHINE
ROOM  DISCHARGE
(DISCONTINUED)
   HIGH LEVEL ALARM

F> PUMP FAILURE

(T> CONDUCTIVITY
                     PROCESS WATER
                    COLLECTION PIT
                       MACHINE CHESTS
                  ooo
                    VACUUM PUMPS
          MAIN  EFFLUENT LINE
                EAST MACHINE
               ROOM DISCHARGE
        Figure 12.  Paper machine effluent system—alarm points,

-------
is given to allow for corrective action to be taken; thus, if the
spill can not be averted, its impact will certainly be dimin-
ished.  The seven items monitored are:

      (1)  Chemical mixing tank.

      (2)  Clarified process water tank.

      (3)  Unclarified process water surge tank.

      (4)  Refining water supply tank.

      (5)  Pulp mill wash dilution tank.

      (6)  Process water collection pit.

      (7)  Repulper sump.

      Two pumps are also included in this monitoring system.  The
first is a pump supplying process water to the DSM screen for
clarification.  Should this pump fail, an alarm will be triggered
by a  pressure switch indicating low discharge pressure.

      The second is the backup pump for the main sewer effluent
pump.   This pump is monitored for "on-time" only, an indication
of primary pump failure or excessive flow to the flume.

      Figure 11  (page 27) and Figure 2  (page 8 ) indicate the lo-
cation  of alarms and sensors schematically.

      As with any complex mechanical-electrical system, a period
of operational development must be endured.  As an example, poly-
shrink  tubing and time delays had to be installed on the tank
high  level probes to keep them from reporting falsely high read-
ings  caused by splashing.

      Although the monitoring system has not, and will not, elimi-
nate  upsets, it is safe to say that the adverse impact of many
potentially severe upsets has been either averted or greatly
minimized by this system.

REVERSE OSMOSIS SYSTEM

      By the spring of 1973, the revision of sewers and surge con-
trols had stabilized the mill process water system to the degree
that  the losses caused by variable water inputs taxing the volume
limit of the system became evident.  Over a period of months of
analyzing loss data, it was determined that during these times
when  excess volume was entering the system the normal rate of
buildup was from one to a maximum of 56.7 liters per minute
(15 gpm).  It was subsequently decided that, with the surge
storage available for sudden shifts of inventory, a reverse

                               31

-------
osmosis plant capable of 75.7 liters per minute  (20 gpm) of
product water would be suitable to keep the long-term system
volume under control.  The plant feed flow of 340.6 liters per
minute  (90 gpm) of clarified process water was then set by the
Fluid Sciences Division of Universal Oil Products Company, based
on striking an optimum between feed pumping power requirements
and limiting solids increase through the plant, because the
higher the solids the less driving force for water production.

Plant Feed Characteristics

     The feed stream to the reverse osmosis plant is clarified
process water taken from the line supplying the paper machine
showers.  Chemically, it is a solution of 4-6% dissolved solids
containing wood extractives and sodium lignosulfonates character-
istic of high yield NSSC hardwood pulping.  The stream also con-
tains an average of 300 ppm of suspended solids, which are by
nature a mixture of semicolloidal solids and small fiber debris.
The feed is supplied to the reverse osmosis plant from the mill
process at a temperature of 60-65°C (140-150°F), a pressure of
7.03 kilograms per square centimeter (100 psi), and a pH ranging
from 5.6 to 6.0.

Reverse Osmosis Theory

     Osmosis is defined as the tendency of a fluid (water) to
pass through a semipermeable membrane (cellulose acetate) into a
solution of higher concentration, so as to equalize concentra-
tions on both sides of the membrane.  If a pressure is exerted
on the more concentrated solution side, the flow will be de-
creased.  As the pressure on the concentrated solution is in-
creased, a point will be reached at which the osmotic flow has
stopped entirely.  This pressure is called the osmotic pressure
of the solution and is a property of the solution.  The osmotic
pressure is a function of not only the type of solution but also
the soluble solids concentration and temperature.  For example,
our process water has an osmotic pressure at 35°C  (95°F) of about
12.3 kilograms per square centimeter (175 psi) at 5% soluble
solids and 24.6 kilograms per square centimeter  (350 psi) at  10%,
whereas a sodium chloride solution at the same temperature has an
osmotic pressure of 42.4 kilograms per square centimeter  (603
psi)  at 5% and 94.2 kilograms per square centimeter  (1340 psi) at
10% soluble solids.

     Increasing the pressure beyond the osmotic pressure at a
given solution condition of temperature and percent solute causes
a reversal in osmotic flow of the solvent and is the basis of
the reverse osmosis process.

     The peculiarities of the osmotic passage of a solvent
through a membrane is the most important difference between the
filtration and reverse osmosis processes.  Osmosis depends on the


                               32

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selective property of a membrane, that is, solvent can pass
through the membrane, while one or more of the soluble components
can not do so.  Therefore, in the reverse osmosis process, re-
moval of the solvent increases the concentration; and, therefore,
the osmotic pressure of the concentrating solution increases with
a subsequent decrease of the flow of the solvent under a fixed
pressure.

     In a plant where the goal is to remove water and not to gain
concentration, it can easily be seen why a maximum plant feed
flow is necessary to minimize this concentration effect.  This
also is the basis for a lower limit on velocity passing the mem-
brane surface so that a concentration gradient is not created by
laminar flow.  Velocity effects will be discussed further under
fouling problems.

Reverse Osmosis Plant Interface

     The role of the reverse osmosis plant in the general mill
scheme has been previously described.  Figure 13 illustrates the
interface of this operation to other mill processes.  As the
temperature of the module membrane is limited to 40°C (105°F),
the plant feed is cooled to 38°C  (100°F) in a plate-style heat
exchanger; boiler makeup water is used as the cooling medium.
There are two product streams from the reverse osmosis plant
permeate  (product water) and a concentrate.  Initially, the
permeate was to substitute for a portion of the city water used
for pump and agitator seals.  In order to avoid corrosion, this
was not done as all small pipelines in this system are steel or
copper; and although low in BOD, the permeate has a pH of 4.5
due to a trace of acetic acid.

     The concentrate, or the second stream, can be routed back,
when necessary, to the process water collection pit; but it
normally flows to the pulp mill wash dilution tank to be used in
the countercurrent liquor washing operation.  This use helps
increase final liquor solids and promotes minimum evaporator
usage.

Reverse Osmosis Hardware

     The equipment received from Universal Oil Products
(Figure 14)  consisted of three separate packages:  the pump
assembly (right side), control center (center), and six module
racks (left side).  The pump rack consists of eight Goulds multi-
stage booster centrifugal diffuser-type pumps of which two are
25 Hp 47-stage feed pumps and six are 10 Hp 23-stage recycle
pumps.   Also included in the pump package are the magnetic flow
meters,  valves, and sensors (Figure 15).

     The control center is primarily electronic.  The right panel
consists of amp meters, pump controls, and electrical switches


                               33

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CLARIFIED  PROCESS WATER
  TO MACHINE SHOWERS
                                                                   DISCHARGE
                                                     PERMEATE
                 BOILER  MAKEUP
                 (CITY WATER)
                      1
                     HEAT
                   EXCHANGER
        REVERSE
         OSMOSIS
         PLANT
                                                                 PULP MILL WASH
                                                                 DILUTION TANK
                                                     CONCENTRATE
HEATED
MAKEUP
                                       BOILER
                                       WATER
PROCESS  WATER
     PIT
                   Figure 13.  Reverse  osmosis  plant interface.

-------
.
                             Figure 14.   Reverse osmosis plant.

-------
Figure 15.  Pump assembly rack




               36

-------
for starting and stopping the reverse osmosis unit.  The left
panel has the alarm annunciator panel; power, flow, and opera-
tional hour totalizers; adjustable timers; recording charts; and
necessary controllers.

     The 288 modules are incorporated equally on the six racks
with 16 rows on each rack and three modules in each row.  Each
module contains 18 porous tubes which are fiberglass, filament
wound, and resin bonded.  The membrane, formed from cellulose
acetate, is on the inner surface of the fiberglass tubes and pro-
vides 1.55 square meters (16.7 ft2) of membrane surface per
18-tube module.  These tubes, approximately 2.23 meters long
(88 in), are contained within a hexagonal shroud and connected
internally in series by means of two molded heads.
                   /
     Feed is piped into either of the two ports at the high pres-
sure end; and after nine complete round trips (18 tube lengths),
it exits at the same end as it entered.  The other port in the
feed end becomes the concentrate exit  (near the wall, Figure 16).
Water molecules permeate outward from the 18 pressurized tubes
through the semipermeable membrane and the porous tube wall into
the shroud.  Permeate is collected inside the shroud and exits
from the outlets at the opposite end under low pressure.

Reverse Osmosis Process Plant Flows

     The clarified process water feed flow, under conditions of
full plant operation  (Figure 17), is 340.6 liters per minute
(90 gpm).  The two feed pumps pressurize this literage to 31.6
kilograms per square centimeter  (450 psi) before it combines with
the recycled concentrate; the combined flows—946 liters per
minute  (250 gpm)—are boosted by the six recycle pumps to 42.2
kilograms per square centimeter  (600 psi).  This module feed is
supplied to the six identical module rack assemblies arranged in
parallel.  After passage through the 96 module rows, the indi-
vidual rack concentrate flows are recombined in the return
header; a portion, the concentrate discharge—255 liters per
minute  (67.5 gpm)—is returned to the pulp mill, and the remain-
der, still under pressure, is recombined with fresh feed to main-
tain the high velocities necessary to minimize fouling.

     The permeate is collected in small tanks above the six
module racks before combining as the total permeate flow.  The
tanks are necessary to return permeate to the modules during the
pause or rest cycle, during which osmotic backflow removes accu-
mulated material (fiber debris) from the membrane surface.  The
modules are sloped to ensure that the individual tubes are
surrounded by permeate  (Figure 16).
                                37

-------
Figure 16.  Module rack,




            38

-------
     CLARIFIED
      PROCESS
       WATER
       FEED
vo
                                                                               PERMEATE
                                                                               RESERVOIR
                         CONCENTRATE
                           RETURN
                                                                      PERMEATE
             FEED PUMPS
                                         DISCHARGE

                               CONCENTRATE
 RECYCLED
CONCENTRATE
                              RECYCLE
                               PUMPS
                                           MODULE
                                            FEED
                          MODULE  RACK
                          TYPICAL I OF 6
                                                                       MODULE ROW
                                                                        TYPICAL
                                                                         I OF 16
                                                                        PER RACK
                            Figure 17.   Reverse osmosis flow diagram.

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Reverse Osmosis Plant Controls

     The control and monitoring instruments for the plant are
relatively straightforward (Figure 18).  The feed flow and total
module feed are measured, controlled, and totalized.  The per-
meate is measured and totalized.  Pressure on the modules is
maintained by controlling concentrate flow.  Other necessary
variables are measured and recorded—electrical power consump-
tion, pH, temperature, conductivity of the permeate, etc.  All
the indicating and recording devices were provided to ensure
ample data for reporting the performance of this demonstration
plant.  Also, adjustable timers controlling the pause and
operating cycle times are included.
                               40

-------
  CLARIFIED
PROCESS WATER
     FEED
                                          PERMEATE
           PH  SENSOR

           TEMPERATURE  SENSOR

           SOLUBLE  SOLIDS ANALYZER
          MAGMETER
                               CONDUCTIVITY
                                  SENSOR
                                   TURBINE
                                    METER
                    |_FLOW _CO_NTRO_L_
                        SIGNAL
             FEED
            PUMPS (2)
&4-^
  >  ^
                                                                 MAGMETER
                                          RECYCLE
                                          PUMPS (6)
                                   T
                    |_FLQW __ CONTROL^ J
                         SIGNAL
                                                                            MODULES
                                                          (__ PRESSURE
                                                            CONTROL
                                                                           CONCENTRATE
                      Figure 18.  Reverse osmosis plant  control.

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                            SECTION 5

                      OPERATING EXPERIENCE


 IN-PLANT ENVIRONMENTAL EFFECTS OF MILL WATER SYSTEM CLOSURE

     From  1968 to  1973, the total dissolved solids in the mill
 process water rose from 0.7% to 5.2%.  This was a consequence of
 intensive  process  water reuse.

     Several effects from the increased dissolved solids were
 noticed.   First, the buildup of dried liquor solids on paper ma-
 chine  surfaces increased.  This was particularly true on the
 underside  of the machine above the wire pit.  A first approach
 to correcting this problem was to install under-machine, side
 entry, atomizing steam showers to increase the humidity and thus
 prevent the drying of soluble solids.  Because of adverse mist
 outside the machine, this eventually gave way to installing vinyl
 side curtains on the machine and abandoning the atomizing steam
 showers.   The side curtains appear to avoid air circulation and
 trap the necessary humidity under the fourdrinier.

     By reusing process water, the system temperature also in-
 creased.   The rise was approximately from 60°C  (140°F) to 71°C
 (160°F).   This temperature rise made necessary the reconstruction
 of the machine room ventilating system.  A canopy had to be
 placed above the fourdrinier to keep condensed water vapor from
 falling onto the paper machine wire.  More air was needed to re-
 duce the room air  temperature as well as remove excess humidity.
 An additional 30 Hp was required to bring in fresh air and prop-
 erly distribute it, and another 30 Hp was required for a second
 roof fan above the fourdrinier paper machine to expel warm, humid
 air.  In addition  to the above changes, the machine tender aisle
 ventilation system was reworked, with another 25-Hp fan capacity
 added to this system.

     These changes have not only improved employee comfort but
 they have  also reduced the in-house fallout of process water
 solids.  These modifications were made over a period of several
years at a cost of approximately $115,000.
                                42

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PROCESS WATER SYSTEM ADDITIVES

Slimicides

     The potential for slime growth is significantly enhanced by
closing the process water loop.  This is mainly due to the in-
creased nutrient concentration in the system.  Bacteriological
slime, a gelatinous secretion of undetermined type bacteria,
under certain conditions can detach from vessels and pipe walls
to create runnability problems for the paper machine.

     The general level of slime growth can be controlled by the
use of slimicides and by maintaining a sufficiently high system
temperature.  In the early weeks of system closure, little in-
crease in slime growth was noted.  However, the first time the
mill's recovery plant had a lengthy shutdown after closure, the
process water system temperature dropped due to lack of makeup
heat from the recovery plant.  With the cooling of the now en-
riched process water, the bacterial growth mushroomed.  The re-
sultant increase in loosened slime globules caused numerous
breaks of the wet web leaving the couch roll on the paper machine.
The immediate remedy was to return to fresh water on the paper
machine showers, followed by a thorough cleaning of the entire
process water system.

     Slimicide was then used to suppress new growths of slime-
forming bacteria.  The level of slimicide addition was then ad-
justed to the minimum amount while just maintaining control of
bacterial growth.

     Currently, two types of slimicide are used, an organic
dibrominate and methylene-bis-thiocyanate.  These materials are
alternated from drum to drum.  The slimicide addition occurs
every four hours with 22.7 to 45.4 kilograms per day  (50 to 100
Ib/day) being added to the DSM screen supply tank.

     Samples of process water are taken at four locations:  the
inlet to the headbox, the clarified process water storage tank,
the process water collection pit, and the reverse osmosis plant.
Normally, the desired level for total colony count is 100,000
or less at the headbox and 500,000 or less in the rest of the
system.  Although these are desired levels, actual counts may
vary from 1000 to several million for short periods without any
visible indication of slime.

     The daily process water samples are cultured in  100 x 15
millimeter Petri dishes using tryptone glucose extract agar as
the culture medium.  The cultures are incubated at 37°C  (100°F)
for 48 hours.
                                43

-------
 Defoamers

      The closing of the process water loop caused the temperature
 to  rise to  a high of  71°C  (160°F) at the paper machine headbox
 and a low of 62.8°C  (145°F) at the surge capacity storage tanks.
 The defoamer used prior to the closed system was a combination of
 oils (steric fats and fatty acids) and isopropyl alcohol.  The
 defoamers had to be heated to affect solution and were water
 emulsifiable.  The combination of higher temperatures and dis-
 solved solids made this type of defoamer ineffective.

      After  an extensive investigation, a defoamer was found which
 met all the necessary pH range and temperature requirements of a
 closed system.  Basically, the defoamer was a mineral oil carrier
 with a silicone coated silica suspension.  The defoamer was sur-
 face active and immiscible with water.  The application was on
 and around  the paper  machine with a daily rate of usage at
 approximately 13.6 to 59.1 kilograms per day  (30 to 130 Ib/day),
 depending on machine  conditions.  The system for addition of the
 defoamer is completely automated and will respond according to
 existing conditions.

      A different defoamer was used in the secondary fiber re-
 pulping system, specifically on the water dropleg on the Impco
 thickener.  Foam develops here due to the cascading of process
 water into  the standpipe.  This defoamer is similar to the one
 on  the paper machine  but has some esters added.  The machine
 defoamer can be used  in this area also, but doesn't have the same
 efficiencies.  Use at this point amounts to approximately 90.9
 kilograms per day  (200 Ib/day).

 PROCESS WATER SYSTEM  ASH BUILDUP

      Although ash buildup in a closed paper mill water system is
 not  easily  observed or measured as is slime or soluble solids
 buildup, it is real and can be a problem due to increased refiner
 plate wear.  Following the same pattern as that of soluble solids
 with  system close-up,  ash continued to increase until 1975 when
 a means was found to  remove the normally recirculated ash from
 the  system  in a concentrated, reasonably dry form.  Approximately
 one-third of the ash  percent is normally silica, and the remain-
 der is calcium oxalate.

      Figure 19 is a diagram of the complete centrifugal cleaning
 and reject  refining system.  Abrasive material is removed at two
points.  The first is  relatively coarse sand, gravel, and metal
removed by  a MagnaCleaner just before the second stage of
centrifugal cleaners.  The second is the reject stream from a
 13-centimeter (5-in)  centrifugal cleaner operating on the efflu-
ent from a Hydrasieve.  The fine recirculated ash in this loop is
at its greatest concentration of any point in the system.  After
                                44

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              13 PRIMARY CLEANERS
               WITH VACUUM  TANK
^ 	
TO PAPER
MACHINE
m
• •
• mm



                                                                     HYDRASIEVE
cn
                                    MAGNACLEANER
                                                         4 SECONDARY
                                                        CLEANERS WITH
                                                          STOCSAVERS
                                                                                    PRIMARY
                                                                                    REFINING
                                                             REJECTS
                                                             14  TONS
                                                             PER DAY
COARSE SAND
 AND METAL
 400 */ DAY
                                                                                   TO MACHINE
                                                                                      CHEST
                                                   TO  REFINERS
                                            5  INCH CLEANER
                                            WITH  STOCSAVER
       FAN  PUMP
                                     INERTS  700**  DAY
                                     PRESSED CHIPS
                                     FROM WASHING
                                     SCREW PRESS
                                 Figure  19.   Grit removal system.

-------
being rejected  from the small centrifugal cleaner, the separated
ash  is dewatered in a grit chamber and removed by a lift screw
to be hauled away to landfill.

REVERSE OSMOSIS PLANT OPERATING PHILOSOPHY

     The reverse osmosis plant has operated 60% of the mill
operating time  during the two years since it was installed.  The
excess inventory of process water required its use only about 15%
of the mill operating time.  The plant was run as continuously as
possible because of the project goal to determine membrane life
and  rejection efficiency over an extended period of time.

     The 40% downtime was the result of a number of problems—
plant control system and piping revisions, pump maintenance,
module replacement, and plant descaling.

Reverse Osmosis Plant Performance

     After a few initial revisions in the instrument control
scheme and hardware, the plant control has been very complete and
maintenance has been minimal.  The automatic features of the
plant have resulted in reliable unattended operation.

     The pumps  have operated well to produce the intermittent
high pressures  necessary for plant operation but have required
a high degree of maintenance to keep them efficient.  This
aspect is more  completely described in the section entitled
"Reverse Osmosis Pump and Pump Seal Problems."

     The third  component of the plant, the modules, constituted
the  main research and development area of the project.  This part
of the project was slowed considerably by problems relative to
the  porous fiberglass support tubes for which details are also
described under "Reverse Osmosis Module Fiberglass Membrane
Support Tube Failure."

     The module membrane used in this plant is of a medium per-
meability grade.  The quality of the permeate from this membrane
has  been better than specified in the listing of plant bid re-
quirements.  This property, as well as the other normal operating
parameters, are listed in Table 10.

     Power consumption of 82.0 kilowatt-hours per 3785 liters
(1000 gal)  of permeate has been less than other alternate evapor-
ative methods of pure water removal.  Comparative costs are
described in the report section "Economic Evaluation of Reverse
Osmosis vs. Evaporation."

     The only disappointment has been in the area of reduced
productivity brought about by membrane aging.
                                46

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           TABLE 10.   TOTAL REVERSE OSMOSIS PLANT
                AVERAGE OPERATING PARAMETERS

   (See Appendix A for Test Procedures and Calculations)
Item
Soluble solids
Sodium
BOD 5
Color
PH
Item
Soluble solids
Sodium
BOD 5
Color
PH
Feed
(ppm)
54,400
6,500
13,900
112,500
5.8
Permeate
(ppm)
372
62
1,005
65
4.1
Concentrate
(ppm)
66,900
8,000
17,600
146,800
5.8
% Rejection







Specified Actual
98.0 99
none 99
96.0 98
99.0 99
—
.86
.86
.56
.94
-
                Item
Design
Actual
       Flux gallons
         (per day per sq ft)
         at 5% feed solids,
         600 psi  (41.4 bar)
         module feed pressure,
         and 100°F (3?OC)
 6.65
 5.13*
Power consumption per 1000 gallons permeate  =  82.0 kwh*
*average for two years
                              47

-------
     Figure  20 is a comparison of the flux at 5% dissolved solids
obtained on  two different plant complements of modules over a
period of approximately 2000 hours of exposure.  This figure is
limited to the operational time data we have available on a full
plant basis  as of this date.  The original modules supplied with
the plant were replaced due to a material defect, allowing the
evaluation of a second set.  In both cases, the flux decreased
gradually over the 2000 hours as the modules aged.  The differ-
ence observed in the flux levels shown by the two groups has not
been determined but is believed to be related to the original
membrane characteristics.  All attempts to return to starting or
even design  flux—11.29 liters per square meter-hr (6.65 GFD) at
5% dissolved solids—have been futile.  This rate of drop in flux
does not continue indefinitely but tends to level out after
approximately 2500 hours.  This can be observed by the longer
term flux exposure times on the individual module (replacement)
racks installed over the last 14 months  (Figure 21).  Evidence of
the long-term flux stability after the initial drop can be seen
up to the longest rack exposure time of 7000 hours.   The initial
drop in flux which occurs within a 24-hour period after the mem-
brane is installed is recognized in the industry and is known to
be caused by initial compaction of the membrane.  Whether the
drop after this is continued slow compaction or some other phe-
nomenon is not known at this time.  There has been no deterio-
ration in membrane rejection of soluble solids or color during
this period  of 7000 hours.

REVERSE OSMOSIS MODULE FIBERGLASS MEMBRANE SUPPORT TUBE FAILURE

     The first six months after plant acceptance saw module
failure, due to tube structural strength loss, reaching an
untenable number, as high as 21 modules per 100 hours of exposure*
Initial failures, generally occurring close to the ends of the
tubes, were  thought to be caused by questionable manufacturing
processes or lack of employee care in positioning the tubes for
the delicate tube cut-off operation.  When further ruptures
occurred randomly spaced along the entire length of tubes, it was
realized that these new failures were a result of some mysterious
and unknown  cause.

     An analysis of tube processing and qualification data showed
no correlation of the rupture phenomenon with various manufac-
turing variables.  The location of failed tubes within the
module appeared to have no correlation with failure incidence.
The one ominous feature that did correlate was the length of
exposure to  the process water feed stream.  The history of 4000+
hours of successful piloting with several modules was of little
benefit in the light of this new reality in which tubes were
rupturing in less than 300 hours.

     Tube burst strengths had dropped during exposure from 276
bars (4000 psi), as originally manufactured, to as low as

                                48

-------
•c*.
vo
     o

     9
     Q
     U.
      I

     X
                                                               •-ORIGINAL MODULES

                                                               A-REPLACEMENT  MODULES
                     2OO
4OO
600     800    1000     1200    I40O

     OPERATING  EXPOSURE, HOURS
1600
I8OO
                            Figure 20.  Flux performance comparison.

-------
01
o
ID -*


n ,
0
m
fO 7
'
1 0 '
CO
.
3
Li- d


;




t
b

if
n A
i






10






oO°






OO 20






yv
 O












3 n





O A RACK
A B RACK
O C RACK
Do





A On
n ^





RACK





o





00 3000 4000 5000 6000 70













00
                                            OPERATING  EXPOSURE,  HOURS
                             Figure  21.   Cleaned module flux data.

-------
166 bars (2400 psi) and even 124 bars  (1800 psi).  With all manu-
facturing processes and quality control procedures tightened to
eliminate any possible causes from the manufacturing end, it was
recognized these premature ruptures could only be caused by the
chemistry of the feed stream as it related to and affected the
mechanical integrity of the tube structure itself.  Samples of
raw and aged tubes plus samples of feed and permeate liquids were
submitted to Universal Oil Products' Corporate Research Group for
analytical investigation.

     Analyses of permeate and feed showed acetic acid present in
both, demonstrating the tube was being exposed to an acidic
environment continuously, albeit in low concentrations.  Ele-
mental analysis of the tubes' resin system showed no leaching
of the components.  Ash contents of raw and aged tubes were also
similar.  Submitting the tube samples to Scanning Electron
Microscopy showed the glass fibers had been corroded and etched
severely, giving them the appearance of "swiss cheese" rather
than a long, smooth, and round filament.  Xray analysis indicated
a loss of Mg and a higher ratio of calcium-to-silica content in
the aged fiber.  The glass then being used contained basic glass
elements in a certain ratio.  It was determined that the acetic
acid of the feed stream and the permeate altered the chemical
composition of the glass itself, allowing the acidic water to
etch the more soluble elemental' portions.

     The photographs obtained with the Scanning Electron Micro-
scope are presented in Figure 22.  An unexposed fiberglass tube
is shown in the top two photos at different magnifications.  The
lower two frames are duplicate magnifications of a tube exposed
to acid permeate.

     The conclusion was drawn that failure of the tubes at Green
Bay was due to corrosion degradation of glass fibers by the
acidic permeate.  Continued exposure time caused a sudden drop of
strength from 124 bars  (1800 psi) to the 41 bars  (600 psi) opera-
ting pressure due to the failure of microcracks, introduced by
the leaching process, and the growth of these cracks by flexure
during startup and shutdown cycling.

Action Taken to Correct the Problem

     In addition to their Corporate Research's efforts, Universal
Oil Products' Norplex Division, with experience in the production
of composite laminates using resinous glass fiber-filled tech-    :
nology, Owens Corning Fiberglas' Technical Center personnel, and
a consultant, experienced in resin/glass fiber structures, were
all engaged to assist in finding a solution.  The search was
begun to find a glass and resin combination that would stand up
to Green Bay's feed stream and operating conditions.
                                51

-------
Figure 22.  Photomicrographs—new (top) and aged tubes  (bottom)
              (furnished through the courtesy of
         Universal Oil Products, Corporate Research).
                               52

-------
     A major problem in developing an  improved tube structure
centered about finding tests that would provide accelerated data
which could quickly and reliably correlate to long-term exposure
in the commercial application.  Selection was finally made of a
water boil test over predetermined time periods from two to as
long as 1200 hours.  Additionally, a rapid cycle life test was
developed in which tubes were subjected to an acidic water
solution at 49°C  (12QOF) while full modules were pressurized to
41 bars (600 psi), held for 60 seconds at pressure, and then de-
pressurized to atmospheric pressure for 30 seconds to complete
one cycle.  This cycle was repeated, usually many thousand of
times, until failure occurred.

     The ultimate test, of course, in  order to check the effec-
tiveness of any improved tube structure, was in their being
placed in actual operation on the Green Bay unit.  Each tube
improvement showing significant results in both static water boil
and dynamic life cycle tests was duplicated to get the required
number of tubes to assemble into a module for placement in ser-
vice.  Ultimately, 17 tube improvements were placed in service
after prescreening (by the accelerated tests at Fluid Systems)
suggested their ultimate success in the field.

     Eventually, one tube's resin/glass composition emerged as
superior to all others.  It consisted of a more chemically inert
glass fiber and new resin combination  that overcame an encoun-
tered, secondary problem of loss of old resin to new glass
adhesion.  The final new resin/new glass combination provided
an adequate matrix for glass bonding, glass distribution, and
tube poro s i ty.

     With on-board accelerated testing continuing to show good
results, and units at Green Bay with several hundred hours ex-
posure to the process water feed, it was decided to retube the
entire plant with the new version.  The rebuild of the Green Bay
plant commenced January, 1975, and has continued through the
present date with the final 75 modules, including 26 spares,
scheduled for installation in February, 1976.  A tremendous
improvement in support tube life was achieved with the new resin/
glass composition.  This improved life is shown graphically in
Figure 23.  The originally supplied modules are compared with the
new modules based on cumulative percent failures with exposure
hours.  Unfortunately, we have only an exposure time of 6000
hours on the new tubes and cannot predict what the maximum effec-
tive module life will be.  To date there have been fewer than two
dozen module failures which have been ascribed to tube ruptures,
and these few have been determined to have been caused by manu-
facturing variances rather than structural deficiencies.  When a
failure is caused by a flaw, correction requires only the replace-
ment of one tube of the 18, and the module can be placed back in
service.   This was not the case previously with the original
modules,  as commonly all the tubes were structurally weakened by


                               53

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m
     UJ
     o
Q
LU
<3O —
fiO
7A
fiO
crx
2in

OU
20 —
iu —
f\









A








A
A
1 • • '




A '
An,
A



,H • •!










1 " '

A "ORIGINAL" MODULE FAILURES
• "IMPROVED" MODULE FAILURES








• 1








• I
1





















                     1000
                         2000      3000      4000      5000


                                OPERATING   EXPOSURE,  HOURS
6000
7000
               Figure 23.  "Original" vs. "improved" module failure experience.

-------
etching when the first failure occurred.  The oldest tubes of
improved structure have over 8000 hours exposure and show signs
of lasting well into the second year of operation, considerably
beyond the warranty period.

     As a result of the problem experienced at Green Bay and its
ultimate solution, Fluid Systems has incorporated the new im-
proved tube as its standard product for all high pressure reverse
osmosis applications, a technical development which has already
paid bonus benefits in providing the answer to another applica-
tion where the older tube version showed shortened life in the
field.

REVERSE OSMOSIS MEMBRANE FOULING

     Membrane fouling continues to be an area warranting further
research and development.  For a more definitive explanation of
membrane fouling, reference is made to the work done by the
Institute of Paper Chemistry, entitled Reverse Osmosis Concen-
tration of Dilute Pulp and Paper Effluents, USEPA, 12040 EEL,
02/72. (2)

Observed Nature of Membrane Fouling

     Membrane fouling by mill process water takes place by
seemingly multiple, complicated, and not well understood mecha-
nisms; however, the fouling observed in the Havens-type tubular
module can be classified into two distinct types.

     The first type of fouling is caused by fiber debris and
wood fines.  Although the process water passing the membrane con-
tains only a small amount of filterable fines, after prolonged
exposure, debris collecting on the membrane will significantly
reduce the membrane permeability.  This debris is always present.
It is that passing the two-step filtering process to make the
water suitable for use on paper machine showers.

     The second type of observed fouling is scale buildup.  After
an operating exposure of 750 to 1000 hours, a tough scale can
form on the membrane surface, reducing the membrane flux from
1.7 to 5.1 liters per square meter-hr  (1 to 3 gal/ft2-day).
Analysis indicates that the process water system is normally
saturated with respect to calcium; therefore, the propensity to
form insoluble calcium salts is extremely great.  Calcium oxalate
has been identified as the major foulant material in module scale
examined by Scanning Electron Microscopy.  The oxalate anion is
a naturally occurring constituent found in varying amounts in
hardwood bark.  Red oak contains a relatively high concentration
of oxalate.  Red oak chips are regularly received as a component
of the mixed hardwood wood supply to the mill.  Calcium oxalate
will salt out of solution upon cooling to form an extremely
                                55

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insoluble scale.  As the process water feed to the reverse
osmosis plant must be cooled from 65°C (150°F) to 38°C  (100°F),
the reaction takes place quite readily on heat exchanger, pump,
and piping, as well as membrane surfaces.

     In addition to the observed long-term fouling, data analysis
indicates short-term effects can be experienced as well.  As an
example, the startup of the fluidized bed reactor requires bed
material  (granular Na2S04 and Na2COs) to be transferred into the
reactor.  Dust carryover of fines is scrubbed out in the
reactor's Venturi evaporator/scrubber.  Normally, this dust
carryover is not a problem as liquor is used as the scrubbing
agent; but during startup, process water and not liquor is pumped
to the Venturi evaporator/scrubber.  This process water, too
dilute for combustion, is brought back to the mill, saturated
with soluble sodium sulfate and carbonate.  The formation and
deposition of relatively insoluble sulfate, carbonate, and
bicarbonate salts accounts for the blinding of the membrane in a
matter of hours.  To avoid this rapid flux drop, the precaution
has been taken not to run the reverse osmosis plant during or
immediately following a reactor startup.  The observed coinci-
dence of reactor startup and drastic membrane flux loss has
ceased since this change was made.

Countermeasures Currently in Use to Remove Fouling

     It was determined in the pilot plant work that an osmotic
backflush would be necessary for 12 minutes in every 120 minutes
of operation.  This osmotic backflush allows for a lifting of
deposited material that has not become physiochemically attached
to the membrane surface.  For further information regarding the
development of this technique, consult the previously mentioned
reference and Recycle of Papermill Waste Waters and Application
of Reverse Osmosis, USEPA, 12040 FUB, 01/72.(3)

     In addition to maintaining a turbulent flow velocity of
1.2 to 1.5 meters per second (4 to 5 ft/sec) and using the
osmotic backflush, it was determined that a daily high velocity
flush with process feed water was necessary to further prevent
the deposition of fiber debris.  This technique involves flushing
one-half the modules at a time for 10 minutes per day using the
full pumping capacity of the plant, directing the discharge back
to the process water recycle system.

     Although these practices are valuable in preventing the
buildup of inordinate amounts of fiber debris, they are not
effective in eliminating the fouling due to insoluble precipi-
tated salts.  It became evident that a cleaning procedure would
be necessary; thus, recommendations were sought from Universal
Oil Products on chemical cleaning techniques that would remove
the foulants without harming the membrane or its support tubes.
                               56

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     The cleaning procedure recommended involves flushing all of
the process water from the modules as a first step.  Next, a 2%
solution of E.D.T.A. Na4 prepared with tap water and pH adjusted
to 7.0 with HCl is recycled through the modules for two to four
hours at a flow rate of at least 13.2 liters per minute (3.5 gpm)
per module row.  A previously recommended 45-hour quiescent soak
period was eventually deleted as no improvement in flux was ob-
served after the initial 4-hour dynamic treatment.  After the
E.D.T.A. treatment, the plant is purged with tap water and flux
checks are made prior to returning the plant to process water.
All discharges of flushing and cleaning waters are returned to
the process water recycle system.

     The flux rate of a given group of modules can be improved
from 1.7 to 5.1 liters per square meter-hr  (1 to 3 gal/ft2-day),
depending on the condition of the modules prior to the time of
cleaning.  In general, this cleaning will return the plant flux
to a level of 8.5 to 10.2 liters per square meter-hr (5 to 6
gal/ft2-day), close to the design capacity.

     Because of the cost of E.D.T.A. treatment, other types of
cleaning agents have been investigated.  One that appears to
show promise is a combination of sodium tripolyphosphate and
enzymatic cleaning agents.  It is commercially available as BIZ,
a home laundry product.  The procedure used to date requires
purging the plant of process water, introducing a 1% solution of
BIZ, pH adjusted to 7.0 with HCl, and allowing this solution to
dynamically wash the modules for three to four hours.  The plant
is then allowed to soak for 12 to 18 hours prior to being flushed
and put back on line.  Limited experience with BIZ indicates the
same type of flux recovery as provided by E.D.T.A., but at
considerably less cost.

Areas of Anomalous Behavior Requiring Further Study     (

     Four years of pilot study and two and one-half years of
full-scale operation have not provided all of the information
needed to understand some of the anomalous behavior observed in
membrane fouling.

     Knowing the many chemical and physical constituents present
in the mill's process water, it is not possible at this time to
explain why on some occasions a flux drop of 3.4 to 5.1 liters
per square meter-hr (2 to 3 gal/ft2-day) will recover without
having changed any operating factors and without cleaning.  It
appears that, on some occasions, factors causing the fouling are
countered by other unidentified changes occurring in the process
water system.

     Six modules have been set apart in a pilot plant receiving
the same feed, at feed conditions, as the main plant.  However,
                                57

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 the means are available on the pilot unit to test various
 techniques of foulant inhibitors and cleaning agents.

     The work to be done in the ensuing year will be aimed at
 identifying  the nature and mechanisms of fouling and developing
 a better understanding of mill operation as it affects reverse
 osmosis plant function.

 REVERSE OSMOSIS PUMP AND PUMP SEAL PROBLEMS

     The pump assembly for the reverse osmosis plant came as a
 completely piped unit consisting of six pumps, valving, and
 interconnecting piping.  There are two feed pumps and four
 recycle pumps of multistage centrifugal design.  The feed pumps
 are Goulds,  Type 3933, with 47 stages; and the recycle pumps are
 Goulds, Type 3933, with 23 stages.

     The first eight months of operation for the pumps seemed to
 indicate acceptable performance.  Then, in the ninth month, a
 critical problem appeared which has been partially resolved at
 this time.   A dramatic drop in pump amperage indicated a loss of
 capacity.  Upon disassembling the affected pumps, it was found
 that a severe degradation of the plastic impellers had occurred.
 The impellers are constructed in two pieces by injection molding
 and then assembled using a solvent bond.  The nature of the
 damage to the impellers indicated that the components had separa-
 ted and then had begun to disintegrate.  Because of the multi-
 staging, the damage was extensive as broken pieces of impeller
 were forced  through the successive units causing further damage.
 Chemical analysis of the process water indicated the presence of
 constituents which could adversely affect the life of the bond
 between the  two impeller components.

     To overcome the problem of impeller disintegration, an
 impeller of  more substantial construction was substituted for the
 original type.  This has significantly reduced the disintegra-
 tion; however, the bond separation continues to be a problem at
 the time of  this writing.

     To further complicate the resolution of the pump problems,
 it became evident that the main support bearings for the impeller
 drive shaft  were deteriorating with use.  The feed pumps have
 five such bearings and the recycle pumps three each.  The problem
 appeared to  be caused by the swelling of the Buna-N bearing.  The
 impeller shaft has a stainless steel sleeve which was abraded
 away by the  swollen bearing.  Once there was sufficient reduction
 of the sleeve cross section, the shaft was no longer firmly held
 in place.  As the drive shaft began to travel eccentrically, this
 caused the plastic impellers to contact the sides of the stain-
 less steel bowls.  The result was debonding of the impeller com-
ponents and  some physical wear to the bowls themselves.
                                58

-------
     In attempting to overcome the bearing problem, new ceramic-
coated stainless sleeves were used to replace the original sleeve
type.  This did not completely eliminate the problem; therefore,
the remaining corrective measure appears to be replacing the
Buna-N bearing material.  A composition bearing has been sub-
stituted for the Buna-N type on one of the pumps.  The bearing
material is a bronze impregnated fluorocarbon polymer that has a
steel backing.  The bearings have functioned for three months in
which time the pump has shown no amp loss or increase in vibra-
tion.  An actual operating exposure of a year or more will be
needed to demonstrate any superiority over the original bearing
type.

     The motor end pump rotary mechanical seals have also re-
quired attention.  Leakage around these seals causes considerable
housekeeping duty as the spray of process water from the leaking
pumps can be extensive.  A new supplier's seal is being substi-
tuted for the original with some success to date.  In addition,
the shaft sleeve at this location on the drive shaft has been
affixed with cementing agents to reduce leakage between the shaft
and the seal shaft sleeve.

     For two years, total plant maintenance cost for parts and
labor  (excluding modules) was $22,330.26.  Of this cost,
$15,877.00 was for pump repairs.  It is hoped the pump repair
costs will be reduced in future years with changes that are
presently being evaluated.
                                59

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                            SECTION 6

                     RESULTS AND DISCUSSION
 RESUME OF MILL OPERATING EXPERIENCE

     The use of  intensive recycling has created some new require-
 ments and costs,  such as replacement of traditional materials
 with more expensive resistant materials; but in many ways, re-
 cycling has resulted in cost reductions, as well.  Production
 cost comparisons  (see pages 61, 62, and 64) illustrate some of
 these cost reductions.  This experience contrasts with increases
 in operating costs required by end of the pipe biological treat-
 ment methods and  thus illustrates the cost advantages of in-plant
 reuse, where possible.

     In obtaining the present point of equilibrium, the process
 water soluble solids content rose from 2.5% in 1970 to as high as
 5.4% in 1974  (Figure 24).  The peak concentration during this
 six-year period was 7.5%.  The system temperature also increased
 from the 54-60°C  range  (130-140°F) to the 65-71°C range  (150-
 160°F).  Both factors affect the corrosive properties of the
 process water.  Also, as has been previously described under
 "Process Water System Ash Buildup," the circulated ash followed
 the same pattern  as the soluble solids until a method was found
 to remove it in  a concentrated form from the system.  How much of
 the increase in  cost of refiner plates  (Figure 24) and wires
 (Figure 25) can be attributed to wear as a result of ash circula-
 tion is open to  conjecture, but it is certainly a major factor.
 The other factors of increased temperature and solubles were
 unchanged in 1975 when costs for both were decreased as ash
 decreased.  In an effort to make a valid comparison, all costs
 related in these  graphs are adjusted for inflation at 9% per
 year.  It is still difficult to make good comparisons for wire
 and felt cost because of the changes in materials made during
 these years.  During the base year, 1971, bronze wires were used;
but from 1972 through 1975, most wires were stainless steel.

     A normal stainless wire will run on the machine about 40 to
 50 days, as compared to seven to ten days for a bronze wire.  We
have tried a few  plastic wires with mixed success initially but
with good results so far in 1976.  Paper machine wet felt costs
                                60

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           PROCESS   WATER  SOLUBLE
            SOLIDS  CONCENTRATION
    1970
        SECONDARY REJECT SYSTEM -ASH
          CONTENT, ACTUAL  PERCENT

    1971 •H^KH 7. f%

    1972

    1973

    1974

    1975
    1971
           REFINER  PLATE  COST
             RELATED  TO  1971
 Figure 24.  Relationship of percent dissolved solids,
secondary reject  system percent ash, and refiner plate
 cost per short ton  product, as percent of 1971 costs.
                           61

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           PAPER MACHINE  PRODUCTIVITY

                 ACTUAL  PERCENT
      1970
      1971
            WIRES-RELATED TO 1971
           WET  FELTS - RELATED   TO   1971


      i97i HiiHBHL I0° %

          l^^mi&vz&M.ajaiiajijaauuanimaBm'm
      1972
      1975
Figure  25.   Paper machine productivity  and clothing  costs
    per short ton product, as percent of 1971 costs.
                             62

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are not any easier to compare.  In 1971, the construction was
mostly wool; but increasing amounts of synthetics have been used
since then so that presently they are 100% synthetic.  As can be
seen, the number of felts used did decrease even though the cost
per ton was slightly higher.

     The last factor, and most important, is paper machine pro-
ductivity.  This is the ratio of the maximum tonnage the paper
machine could produce with no downtime or paper breaks to the
actual tonnage produced.  As can be observed, this aspect was
essentially unchanged by recycling.  Also, although there has
been a substantial increase in wire pit suspended solids  (from
0.2% to 0.3% as a result of closure), there has not been a loss
of machine speed.  Higher process water temperature and higher
average sheet moisture  (computer control) have undoubtedly been
compensating factors.  Furthermore, the increase in water-
extractables in the final sheet—increased from 20 to 41 kilo-
grams per metric ton  (40 to 180 Ib/ton) due to closure—has been
accompanied by a reduction in fiber content at the same basis
weight and, presumably, a corresponding reduction in drainage
resistance.

     A number of other important cost factors are graphed in
Figure 26.  In all cases adjusted for inflation, improvements
were made on the base year of 1971.

     The cost reduction for water and steam are easily recon-
cilable as a result of closing the water system.  Some portion of
the cost of electricity may also be related to water recycle, but
most of this reduction is due to a conscious effort to conserve
power instituted as a management program.

     The last item, maintenance, is the one that might be antici-
pated to rise dramatically; but this was not the case.  Fortu-
nately, most of the mill system in 1971 was stainless steel.  The
two principal non-stainless areas were parts of the fourdrinier
and many of the process pumps.  Pump cases in cast iron con-
struction that had previously lasted two to three years corroded
in as little as five months.  As gradual replacement was neces-
sary, it was made in all stainless pump construction.

     Also, some changes and modifications had to be made at the
fourdrinier.  Grills, catwalks, and general machine components
required more frequent cleaning.  Corrosion of cast iron bearing
housings on wire return rolls was accelerated and required more
frequent replacement until these were replaced in stainless.
Higher temperature greases were required for wire return roll
bearings.  The wire return roll doctor blades had to be changed
from micarta to polyethylene because the life had decreased from
six months to one week.  Corrosion of the fourdrinier main frame
and soleplate is a problem.  There have been recent attempts to
apply an epoxy coating  (Trowelon) similar to that used


                                63

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                MAINTENANCE, LABOR
                    AND  PARTS
                     1OO %
                  ELECTRICITY
                   KWH/TON
                      IOO % I
                     STEAM
                    IO3#/TON
                     WATER
                   GALLONS/TON
                     100 %
Figure 26.  Total mill cost factors per short ton product
       expressed as  percent of 1971 requirements.
                            64

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successfully on concrete in the wire and seal pits.  Only time
will indicate how successful this approach is for long-term pro-
tection of these vulnerable components.  With all the problems,
it is a testimonial to the people involved that maintenance costs
have actually decreased during this period of ever-increasing
recycling.  This decrease, in most part, is due to the proper
selection of materials and good management by the maintenance
staff.

     There have been some process changes relative to recycling
that are continuing problems.  Chemical requirements for sizing
can be increased from two to three times over that required for
washed stock; but as these are not costly chemicals, this can be
tolerated.  We did find it uneconomical to produce wet strength
grades because chemical requirements for equal wet strength are
three to four times greater than those required for washed NSSC
stock, and this additive is an expensive chemical.

     Contaminants from waste paper sources  (such as latex, hot
melts, and asphalt) accumulate in the process water and have a
greater chance of being deposited on paper machine wires and
press rolls.  We have found ways to minimize the problem but not
to eliminate it.

     Any additive to the process water system in a closed loop
becomes a potential hazard in that it may react with other chemi-
cals or with itself at some concentration to produce a chemical
slime.  Therefore, it is necessary to have an overall deposit-
control program, and its control merits the sustained attention
of operating mill management.  Any new additive or change in rate
of an established additive must be carefully scrutinized before
implementation and watched closely for problems after a change
is made.

     Mill shutdowns and subsequent startups can be problems, par-
ticularly if the downtime is of long duration.  The large volume
of process water—1134 to 1512 cubic meters (300,000 to 400,000
gal) in our system—becomes increasingly susceptible to bacterial
growth as it cools.  Increased dosage of the same slimicides used
for control under operating conditions can deter microbiological
activity up to two days in stagnant storage.  If a shutdown is to
be for three days or longer, provision must be made to add addi-
tional amounts of slimicide at two-day intervals and to mix the
stored water by good agitation or by circulation with pumps.

     For long shutdowns (up to two weeks), we have run out our
inventory of paper stock completely, even if the last reels are
not salable.  The machine system is completely emptied and washed.
All process water is stored in three large tanks, which can be
circulated for slimicide addition.  Insulation of these tanks is
                                65

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helpful to retain temperature as long as possible.  In our cold
climate, exposed pipelines must be steam traced and insulated
to avoid freezing.

     Another mill may choose different options to avoid biolog-
ical deterioration of stored water, as each mill has its own
unique system and problems.

MEDIUM STRENGTH CHARACTERISTICS AND CONVERSION BEHAVIOR

     One of the concerns during the progressive closure of the
mill process system was the effect on strength and runnability
as the retained soluble matter in the sheet increased.  A number
of approaches were used to try to evaluate the consequences of
process water closure:

      (1)  Physical testing at the paper machine.

      (2)  A thorough investigation of all customer complaints,
          even minor ones.

      (3)  Continuous monitoring of our own largest corrugating
          plant for changes in strength or runnability.

      (4)  A study was sponsored under the U. S. Environmental
          Protection Agency project to try to determine the
          effects of degree of closure on medium properties
          by testing it under laboratory conditions at the
          Institute of Paper Chemistry.

     The changes at the paper machine were so gradual that is was
impossible to show any immediate, clear-cut effects.  After an
extended period of observation, it has been concluded that the
soluble solids retained in the sheet do have some effect on fiber
bonding.  The change is small up to our normal maximum solubles
level of 6% and affects mullen, tear, and tensile strength but
shows little effect in tests related to stiffness, such as con-
cora and ring crush.  The measured reduction in mullen brought
about by increasing solubles in the process water from 1% to 5%
was a drop from 17.7 to 15.9 kilograms  (39 to 35 Ib), or approx-
imately 10%.

     Reductions in tensile strength would appear to be of the
same magnitude; and tear may be just slightly greater, but our
data are not complete enough to give precise numbers.  Mullen is
run on each set off the paper machine as a routine test, so good,
continuous data are available.  Tear and tensile are not normal
tests.  Based on laboratory testing, there is also some indica-
tion of a reduction in wet web strength with increasing sheet
soluble levels, again of about the same 10% magnitude.
                               66

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     The complaints from our customers were not very indicative
of problems related to mill closure.  There were some intermit-
tent problems involving two' corrugators using archaic tension
systems, but these problems had existed before closure.

     Our Green Bay Corrugated Division is a very modern operation
with an extensive quality control program.  This continuous
quality program was well established before 1971, so comparison
figures were readily available for strength.  Also, our corruga-
tors are run on an incentive program, as are most in this indus-
try, so that any interference with normal operations would be
indicated immediately.  Again, no trends were observed during
closure that could be attributed to the increased solubles level
in the medium.  Table 11 is a comparison of medium and corrugated
board strength for 1970 and 1975, representing open system and
almost completely closed system, respectively.
       TABLE 11.  STRENGTH COMPARISON—OPEN SYSTEM, 1970,
       	      TO CLOSED SYSTEM, 1975
                   Item
                                            Year
 1970
 1975
          Paper machine

            Basis weight
             (pounds/1000 sq ft)

            Concora  (pounds)

            Mullen  (pounds)

          Corrugator

            Flat crush
             (pounds/sq in)

            A Flute

            B Flute

            C Flute

          Standard box, top to
            bottom compression
            strength
             (percent of standard)
 26.3      26.1

 71.8      70.6

 42.0      34.0
 30.8

 48.1

 46.5
100.6
 30.1

 55.0

 40.3
107.4
     The summary of the work carried out at the Institute of
Paper Chemistry is reported in Appendix B.
                                67

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     The slight reduction in bonding strength has not been a
problem involving the paper machine or corrugator.  The problem
has been negated to some degree by the use of slightly more long
fiber in the sheet in recent years.  This is added to the system
in the form of corrugator plant clippings and/or recycled corru-
gated boxes, depending on market conditions.  The percentage has
increased from less than 20% to approximately 30%.  This change
has helped wet web strength, and therefore minimized breaks
occurring at the couch and press sections with no loss of concora
strength.

ECONOMIC EVALUATION OF REVERSE OSMOSIS VS. EVAPORATION

     An economic comparison is presented to show the relative
costs of water removal by reverse osmosis and evaporation.  Up-
dated capital cost data are provided for Green Bay Packaging * s
reverse osmosis plant and the company's two effect evaporator.
Energy cost and maintenance cost data are also provided.

     To provide an effective evaluation, the capital and oper-
ating costs are also provided for a vapor compression evaporative
system.  However, maintenance cost data are based on limited
field experience from other users of vapor compression evapora-
tion.

     For design comparison, it is assumed that the following con-
ditions would hold true for each system:

      (1)  Daily water removal capacity—109 cubic meters
          per day (28,800 gal/day).

      (2)  Annual water removal—19,100 cubic meters
          (5.05 x 106 gal) for 60% annual operating time.

      (3)  Mill process water feed would be essentially free
          of suspended solids with a dissolved solids concen-
          tration of 5% average.

      (4)  Concentrated product will be approximately 7%
          dissolved solids.

      (5)  Product quality should be equally low in
          contaminants.

     For such water removal capacity, the purchased reverse osmo-
sis plant has 288 modules, or 445.9 square meters  (4800 ft^) of
permeable membrane.  It is powered by two 25-Hp feed pumps and
six 10-Hp recycle pumps.  There is also a 1%-Hp permeate pump for
ultimate disposal of the permeate.

     The comparable two effect evaporator would be essentially
the same size as the existing liquor evaporator at the mill's


                                68

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recovery plant.  As the existing evaporator is designed to pro-
duce 150 cubic meters per day  (39,700 gal/day) of condensate, a
somewhat smaller tube surface area would be required than
actually is in use in the recovery plant evaporator.  The two
effect evaporator is designed to use 123 kilograms per square
centimeter (175 psi) steam and up to 1.66 cubic meters per
minute (440 gpm) condenser cooling water.  A normal economy for
this device is 0.68 kilograms  (1.5 Ib) condensate per 0.45 kilo-
grams (1 Ib) steam.

     The vapor compression evaporator would consist of two units
with combined capacity of 109 cubic meters  (28,800 gal) daily.
The necessary heat exchangers would be provided to transfer all
available heat to the feed stream to raise the feed to boiling.
Essentially all energy input is electrical with a small fraction
as steam.
                 1976 Capital and Installed Costs

                                                     Comparable
                                                        Vapor
                           Reverse     Two Effect    Compression
                           Osmosis     Evaporator    Evaporator

 Total installed cost      $324,572     $200,000      $250,000


               1974-1975 Operating Cost Experience

 Operating cost—$/3.785 cubic meters  (1000 gal) purified water

 Energy consumption          $1.70        $8.60         $3.34

 Depreciation                 6.45         3.18          3.71

 Maintenance and labor        2.58          .91           .99

 Total cost—$/3.785 m3     $10.73       $12.69         $8.04


     The total installed costs for reverse osmosis and the two
effect evaporation have been updated from the original costs by
the use of CHEMICAL ENGINEERING plant cost indices.  The vapor
compression installed cost estimate was supplied by the manu-
facturer of such equipment.

     Energy input costs are given based on electricity and steam
costs at the mill for 1974 and 1975.  The vapor compression
energy cost is based on a conservative estimate of 118.8 kilo-
gram-calorie per kilogram (66 Btu/lb) evaporation and is
considered to be a cost of electrical energy.  This energy


                               69

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consumption value is based on the experience of an existing evap-
orator used in a pulp mill application.

     Depreciation charges are assumed to be for a 12-year useful
life on all hardware.  It should be noted that the expected use-
ful module life in reverse osmosis is given at five years—this
may be conservative.

     Maintenance and labor costs for reverse osmosis and two
effect evaporation are based on mill experience for 1974 and
1975.  These costs for reverse osmosis may be excessive because
of the developmental nature of the changes required in the pump-
in system.  The maintenance costs for vapor compression are based
on limited field experience and the assumption that maintenance
will cost 2% per year of the installed cost.
                               70

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                           REFERENCES
1.   Miles, H.   Spent Liquor Disposal Via FluoSolids Combustion
    at an NSSC Mill.  Paper Trade Journal, 154(33):26-31,
    (Aug. 17,  1970).

2.   Wiley, A.  J.,  G. A. Dubey, and I. K. Bansal.   Reverse  Osmosis
    Concentration of Dilute Pulp and Paper Effluents.   U.  S.
    Environmental Protection Agency, Program #12040 EEL,  02/72.

3.   Morris, D. C., W. R. Nelson, and G. 0. Walraven.  Recycle
    of Papermill Waste Waters and Application of Reverse  Osmosis.
    U. S. Environmental Protection Agency, Program #12040  FUB,
    01/72.
                                71

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                           APPENDIX A

          ANALYTICAL AND TEST PROCEDURES AND EQUATIONS
                  USED IN REVERSE OSMOSIS PLANT
     The analytical samples were collected when the operating
conditions of the units were stable.  This required that the
samples be taken at the middle of each pause-operate-pause cycle,
as  the conditions close to the depressurization  (pause) period
were not representative of the majority of the operating period.
Operating data, e.g. pressures, were recorded at the time of
taking samples.

     Frequent measurements were made of the total solids in the
feed and concentrate.  The sample is weighed in an oven-dried
tared beaker, dried overnight at 105°C, cooled in a desiccator,
and reweighed.

     Soluble solids and suspended solids were determined by
standard filtration and oven drying.  A sample is filtered
through a glass fiber pad  (Reeve Angel 934 AH, 11 cm), and the
filtrate is collected.  The pad is oven-dried, cooled in a
desiccator, and reweighed for suspended solids.  The filtrate is
weighed in an oven-dried tared beaker, dried overnight at 105°C,
cooled in a desiccator, and reweighed for soluble solids.
Samples of product water from the reverse osmosis units required
no  filtering.

     Sodium content was determined with a Model 303 Perkin-Elmer
atomic absorption spectrophotometer.  The sample is prepared to
the proper working range using distilled water for dilution.  The
spectrophotometer is operated according to Perkin-Elmer1s
Analytical Methods Manual.

     Analysis of incubated bottles for five-day biochemical
oxygen demand (BODs) was measured according to procedures out-
lined by the Yellow Springs Instrument Company using their
Model 54 Dissolved Oxygen Meter.  Chemical requirements, sample
preparation, apparatus, and calculations described in Standard
Methods for the Examination of Water and Waste Water  (APHA-AWWA-
WPCF), 13th edition, 1971, page 489, Method 219, were used for
the remainder of the analysis.  Volumetric flasks and pipettes
are utilized for measurement and dilution.  A sample, two cubic
centimeters or larger, is pipetted directly into the BOD bottle.
                                72

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     Color is determined by spectrophotometric comparison of the
sample with known concentration of colored solutions.  The proce-
dure is described in NCASI Stream Improvement Technical Bulletin
No. 253, December, 1971.

EQUATIONS

     All flux data (unless indicated otherwise) are reported at
standardized conditions of plant design of 38°C (100°F), a feed
soluble solids of 5%, and a plant feed pressure of 41.4 bars
(600 psi), and have either been obtained at these conditions or
have been corrected to these conditions by the following formula.
Correction is avoided when possible because of additional lab
work and errors in measurement of average module soluble solids.
Permeate flux in gallons per day per sq ft of membrane


                        PPF x T  x 1440              AMFP - 185
                                      2
             No. of modules x 16.67 ft  per module   AMFP - TT
where   PPF = plant permeate flow in gallons per minute
       AMFP = average module feed pressure in pounds per sq in

         "TC  = actual osmotic pressure
          ° = 37* x percent average module soluble solids

         T  = temperature correction to 38°C (decrease by
          c   2.3% above 38OC, or increase by 2.3% below 38Oc)
        185 = osmotic pressure at 5% soluble solids
            = 37* x 5
       1440 = minutes per day
       *average measured osmotic pressure of process water at
        1% soluble solids, as observed at Green Bay Packaging
     Material balances and percent rejections for soluble solids,
BOD, sodium, and color are obtained using plant measurements,
laboratory data, and the following expressions.
                                73

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     Flow Balance:

                          V, = V  + V
                           f    c    p


where   V = volume per unit time of plant flow for feed (f) ,

            concentrate ( ), or permeate ( ).   These are
                         c                p
            obtained from plant instrument measurement and
            checked by actual timed volume collection in a

            container of known volume.
     Mass Balance:
                            - = W  + W
                            f    c    p
where   W = component weight per unit time in each stream of
            sodium, soluble solids, BOD, or color.  These are
            obtained from analytical determination of concentra-
            tion described previously, and the expression for
            each is as follows:
            Wf = Vf x specific gravity x concentration
     Percent rejection for each component is then calculated as
follows:
                   % Rejection =  (1 - W /Wf)100
                                       P  •*•
                                74

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                   Figure A-l.   Typical  routine  reverse  osmosis  data sheet.
Entry
No.
608
609
610
611
612
613
614
615
616
617
618
619
620
Date
1976
2/06
2/10
2/11
2/12
2/13
2/24
2/25
2/26
3/01
3/05
3/09
3/10
3/11
Clock
Hrs.
10378.9
10459.8
10480.0
10501.1
10521.8
10553.9
10570.3
10594.5
10676.0
10762.7
10848.0
10868.5
10889.5
Raw (Process Water) Feed
Flow
Rate
(gpm)
79.5
82.0
81.5
81.0
81.5
82.0
82.0
82.0
81.5
79.5
80.0
80.0
80.0
Temp.
(°F)
98
98
98
98
100
100
100
105
99
99
101
97
98
No. of
Modules
In Service
261
261
258
258
261
261
261
261
258
258
255
258
258
Dis.
Sol.
(%)
5.15
5.08
4.17
5.04
5.12
5.33
5.46
5.12
4.29
5.23
5.64
6.02
6.29
PH
5.6
5.5
5.4
5.5
5.5
5.6
5.6
5.7
6.0
5.7
5.8
5.8
5.9
Module Feed
Flow
(gpm)
240
245
244
244
246
246
240
245
245
240
220
228
237
Feed,-
Press.
(psi)
600
600
600
600
600
600
600
600
600
600
600
600
600
Back
Press .
(psi)
460
450
460
455
451
461
490
471
452
450
450
445
446
Permeate
Conduc-
tivity
(/*mhos )
410
370
280
345
335
385
330
290
260
370
450
500
570
Flow
(gpm)
17.4
16.8
19.8
16.8
17.5
16.5
16.5
16.8
17.1
12.0
11.4
10.8
9.6
en

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                           APPENDIX B

                THE INSTITUTE OF PAPER CHEMISTRY

                       Appleton, Wisconsin

             EFFECT OF MILL WATER SYSTEM CLOSURE ON
                   CORRUGATING MEDIUM QUALITY


                             SUMMARY
     This study was carried out under the sponsorship of Green
Bay Packaging Inc. with the objective of determining the effect
of the degree of closure of their corrugating medium mill process
water system on selected corrugating medium quality character-
istics.  For this purpose, three 30-centimeter  (12-in) wide rolls
of corrugating medium were obtained for each of the following
degrees of mill water system closure:

     1.  "Partially" closed system—process water solubles, 2.9%.

     2.  "Fully" closed system—process water solubles, 5.6%.

     It should be noted that it was originally planned to evalu-
ate a third mill process water condition, namely, an "open"
system, to serve as the reference condition; however, these
samples could not be obtained for the study by the cooperator.

     Each roll of medium was fabricated into single-faced board
shortly after arrival at the Institute and after 60 days storage
to determine its conversion quality.  Conversion quality was
evaluated in terms of (1) the maximum runnability conditions of
corrugator speed and web tensions which could be employed without
causing fractured flutes, (2) flute height,  (3) average differ-
ence in flute height (related to high-low flute formation), and
(4) draw factor.  At each time of fabrication, samples of the
corrugating medium were obtained and evaluated for selected
physical characteristics.

     The following results were obtained:

     1.  In general, the mediums representing both the "partial"
         and "fully" closed mill water system exhibited
                                76

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    satisfactory conversion behavior on the corrugator.  The
    "partial" closure water system medium generally exhib-
    ited somewhat higher physical property levels than the
    "fully" closed system mediums.  However, the differences
    in physical properties may not be of commercial impor-
    tance in many cases.  A more detailed summary of the
    results is as follows:

2.  Conversion Behavior.

    a.  Runnability.

        When evaluated on arrival, the maximum web tensions
        which could be employed without fracture at a
        corrugator speed of 183 meters per minute (600 fpm)
        ranged from 272 to 363 grams per centimeter (1.5 to
        2.0 lb/in) and averaged 327 grams per centimeter
        (1.8 lb/in) for the "partially" closed system
        mediums.  The corresponding results for the mediums
        representing the "fully" closed system ranged from
        182 to 363 grams per centimeter (1.0 to 2.0 lb/in)
        and averaged 272 grams per centimeter (1.5 lb/in).
        The difference in average runnability is not con-
        sidered to be significant in view of the variability
        from roll-to-roll and the levels appear to fall
        within the usual commercial range for good runnabil-
        ity.  After the 60-day storage period, the maximum
        runnabilities of the "partial" system closure medium
        rolls decreased about 109 grams per centimeter
        (0.6 lb/in) on the average.  A decrease of this
        magnitude due to aging is not uncommon.   The medium
        rolls representing the "fully" closed system exhib-
        ited about the same maximum runnability tension
        after aging as was obtained on arrival.

    b.  Flute height and high-low flute formation.

        The degree of system closure did not have any marked
        effect on the flute height of the single-faced
        boards or the tendency of the mediums to form
        high-low flutes.

3.  Physical Characteristics of Medium.

    a.  The Concora flat crush strengths of the "partially"
        closed system mediums averaged 2.7% higher than that
        of the "fully" closed system mediums in the "on
        arrival" tests but the difference was not statisti-
        cally significant.
                          77

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b.  The degree of closure did not have a statistically
    significant effect on the cross-direction edgewise
    compression strength of the medium.

c.  The "partially" closed system mediums exhibited a
    slightly higher water drop time on arrival which was
    statistically significant but the difference may not
    be of commercial importance.

d.  The "partially" closed system mediums exhibited
    significantly higher tearing strengths and tensile
    properties than the fully closed system mediums in
    the "on arrival" tests, but the differences may not
    be of commercial importance in many applications.
                      78

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                           APPENDIX C

                        PROJECT VISITORS

                MAY, 1972, THROUGH DECEMBER,  1976


Number                     Organization or Affiliation

                U. S. Industrial Companies

   2            A & P, National Dairy Division
   3            Aqua-Chem, Inc.
   1            Butter Manufacturing
   1            Chrysler Outboard Corporation
   2            Clark & Vicario
   2            Continental Can Co., Inc.
   2            Dresser Industries, Inc.
   2      '      Eastman Chemical International Co.
   1            W. D. Ehrke Co.
   4            Fabric Research Laboratories, Inc./Albany
                  International Co.
   2            Hammermill Paper Co.
   2            Kenics Corporation
   1            Kimberly Clark Corporation
   1            McGark Strapp & Associates
   2            McMaster-Carr
   1            Milk Specialties Co.
   5            Nicolet Paper Co.
   5            Owens-Illinois
   2            H. C. Prange Co.
   2            Proctor & Gamble
   1            Reed Paper Ltd.
   1            Rex Chainbelt, Inc.
   3            St. Regis Paper Co.
   1            L. D. Schreiber Cheese Co., Ltd.
   1            Scott Paper
   5            Sonoco Products Co.
   5            Stone Container
   1            3M Co.
   2            Universal Foods
   1            Ward's Cheese
   2            WesCor Corporation
   1            Westinghouse
   2            Weston Paper and Mfg. Co.
   2            Whirlpool Corporation


                                79

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Number                     Organization or Affiliation

                Foreign Concerns

   3            ASSI Development Laboratory (Sweden)
   1            Australian Paper Manufacturers, Ltd.
   2            B.D.M.R. Consultants (Canada)
   2            T. W. Beak Consultants Ltd. (Canada)
   3            Broby Industrier AB (Sweden)
   3            Cellulose Attisholz AG (Switzerland)
   3            Daicel, Ltd. (Japan)
   7            Domtar, Ltd. (Canada)
   2            Emsland Staerke (Germany)
   5            Fiskeby AB  (Sweden)
   1            IVL Consulting Ltd. (Sweden)
   1            IVL Swedish Pollution Control Co.
   1            IVL Swedish Water and Air Pollution Research
                  Laboratory
   2            Kon. Scholten Honig. (Netherlands)
   2            LaRochette-Venize Mill (France)
   1            Mitsubishi Heavy Industries, Ltd. (Japan)
   1            Mitsui & Co. (Japan)
   4            MoDoCell (Sweden)
   1            National Environmental Board (Sweden)
   1            ttrebro Pappersbruk AB (Sweden)
   1            Osaka Municipal Technical Research Institute
                  (Japan)
   1            Papeteries de L'Epte (France)
   2            Paterson Candy International,  Ltd.  (England)
   3            Sanyo-Kokusaku Pulp Co.,  Ltd.   (Japan)
   3            Sasakura Engineering (Japan)
   1            South African Pulp and Paper Industries, Ltd.
   1            Tomoegawa Paper Mfg. Co., Ltd.  (Japan)
   1            Woodall-Duckham Pacific Ltd. (Australia)

                Government

   4            Environmental Protection Service  (Canada)
   1            Federal Elected Official
   1            Illinois State Water Survey Division,
                  Department of Registration and Education
   3            U. S. Environmental Protection Agency
   4            Wisconsin Department of Natural Resources

                Tour Groups

   9            American Society for Quality Control Sponsored
                  Tour
   5            Bay City Alternative School
  35            CESA Environmental Education Trainees
  27            East DePere High School
                               80

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Number                     Organization or Affiliation

                Tour Groups  (continued)

  12            Forest Industry Council Sponsored Tour of News
                  Personnel
  13            Green Bay Chamber of Commerce Environmental
                  Committee
  65            Institute of Paper Chemistry
   6            Institute of Paper Chemistry Technical Advisory
                  Committee
  39            Instrument Society of America Sponsored Tour
  22            International Fibre Box Association
  75            Northeast Wisconsin TAPPI Sponsored Tour
  19            Northeastern Wisconsin Dairy Technical Society
  10            TAPPI Sulfite and SemiChemical Pulping Committee
  19            Third SemiChemical Corrugating Medium
                  Superintendents' Meeting Tour
 108            University of Wisconsin-Green Bay
  10            University of Wisconsin-Madison
  12            University of Wisconsin-Stevens Point

                Educators

  13            Institute of Paper Chemistry
   1            Yokohama National University (Japan)
   2            University of Wisconsin-Madison

                Miscellaneous

   1            Chamber of Commerce
   3            News Media  (Press and TV)
   1            Pulp and Paper Magazine
                                81

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                            GLOSSARY
3005:  Biochemical oxygen demand based on oxygen requirements
     needed during a five-day period for stabilization of
     decomposing organic matter in an aerobic biochemical action.

CentriCleaner:  Trade name.  Free vortex cone type cleaner for
     centrifugal separation of shives, dirt, bark, etc., from
     normal wood fiber by density, size, and shape.

compaction:  Decrease of water permeation rate through a membrane
     with time at a fixed pressure and temperature.

concentrate:  The solution exiting from the reverse osmosis unit
     after removal of a portion of the water through the
     membrane.

consistency:  The percentage, by weight, of air dry fibrous
     material in a stock suspension.

DSM screen:  Trade name.  Pressurized nozzle feed screen with a
     curved screen surface.

fluidized bed reactor:  Fluid solids process of burning spent
     liquor to obtain a dry ash in the form of inorganic pellets.

flux rate:  Rate of permeation or transport of water through the
     membrane.

Hydrasieve:  Trade name.  Stationary, three-slope, stainless
     steel, wedge bar screen.

NSSC:  Neutral Sulfite SemiChemical pulping, usually with sodium
     bisulfite, but other bases such as ammonia are also used.

osmosis:  Diffusion through a semipermeable membrane separating
     a solvent and a solution that tends to equalize their
     concentrations.

osmotic pressure:  The hydrostatic pressure required to stop the
     diffusion across a semipermeable membrane between two
     solutions of dissimilar concentrations.
                                82

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pause:  Periodic reduction of the pressure from an operating
     level to atmospheric for the purpose of restoring the flux
     rate lost by the deposition of a fouling material on the
     membrane surface.

process water:  A general term for all waters of a paper mill
     which have been separated from the stock or pulp suspension,
     either on the paper machine or accessory equipment, such as
     thickeners, washers, and savealls.  In a closed system, the
     water which recirculates throughout the mill for pulp
     dilution and showers.

reverse osmosis:  Osmosis in reverse flow through a semipermeable
     membrane when external pressure in excess of the osmotic
     pressure is applied.

spent liquor:  Waste liquor separated from cooked chips and pulp
     containing the residual cooking chemicals and dissolved
     constituents from the chemical cooking of wood chips.
                                83

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                                    TECHNICAL REPORT DATA
                             (Please read Instructions on the reverse before completing)
 i. REPORT NO.
   EPA-600/2-77-241
                 3. RECIPIENT'S ACCESSIOr+NO.
 4. TITLE AND SUBTITLE
  CLOSED PROCESS WATER LOOP IN NSSC  CORRUGATING MEDIUM
  MANUFACTURE
                 5. REPORT DATE
                  December 1977 issuing date
                 6. PERFORMING ORGANIZATION CODE
 7. AUTHOR(S)
  Gerald 0.  Walraven, William  R.  Nelson,  Peter E. DeRossi,
  Richard L. Wisneski
                 8. PERFORMING ORGANIZATION REPORT NO.
 9. PERFORMING ORGANIZATION NAME AND ADDRESS
  Green Bay Packaging Incorporated
  P.  0.  Box 1107
  Green Bay, WI  54305
                  10. PROGRAM ELEMENT NO.
                  1BB610
                  11. CONTRACT/GRANT NO.
                      S-800520
 12. SPONSORING AGENCY NAME AND ADDRESS
  Industrial Environmental Research Lab.
  Office of Research 6  Development
  U.  S.  Environmental Protection Agency
  Cincinnati, Ohio  45268
- Gin., OH
13. TYPE OF REPORT AND PERIOD COVERED
 Final
                  14. SPONSORING AGENCY CODE
                    EPA/600/12
 15. SUPPLEMENTARY NOTES
 16. ABSTRACT
        Over the last 5 years,  the  Green Bay Packaging corrugating medium mill has con-
 verted to an essentially  closed process water system.  The mill is  a net consumer of
 water.  This is due to the greater amount of water carried out of the system with the
 sheet compared to the lower water content entering the process system in raw materials
 Many small dilute water streams are accepted into the process without upsetting the
 water balance.
        When extraneous water inputs do upset the system balance, the condition is cor-
 rectable by thermal evaporation or reverse osmosis'.  The reverse osmosis plant design
 operating performance and economics are described.  Although many reverse osmosis op-
 erating problems have been solved, flux rates are somewhat lower than had been pre-
 dicted.  Other system additions and revisions for process water entrapment, recycle,
 and surge protection are  described.
        When a spill cannot be  prevented, a monitoring system is used by production per-
 sonnel for early detection and correction.  Included in key areas is redundant equip-
 ment to help correct failures quickly.
        Levels of BOD loss  have been reduced from the 20,000 pounds per day range (9072
 kg/day)—1971— to less than  1000 pounds per day  (454 kg/day)—monthly average— for
 1975.   The daily maxima of 4000 pounds per day (1814 kg/day) has not been exceeded in
 any mill operating day during 1975.
             report covers  a period from July 19. 1972. through  February 2, 1976.	
 7.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
    b.IDENTIFIERS/OPEN ENDED TERMS
                                                                           COSATI Field/Group
   Circulation, Water Pollution,  Color,
   Biochemical Oxygen Demand
     Pulping,  Closed  System,
    Reverse Osmosis  Waste
     oncentration, Physical
    Separation, Product
    Quality,Waste Monitoring
    Total Suspended  Solids,
    Waste Control
                  13B
 3. DISTRIBUTION STATEMENT

    RELEASE TO PUBLIC
    19. SECURITY CLASS (ThisReport)
       UNCLASSIFIED
              21. NO. OF PAGES
    20. SECURITY CLASS (Thispage)
       UNCLASSIFIED
             22. PRICE
EPA Form 2220-1 (9-73)
                                                                    4 U.S. GOVERNMENT PRINTING OFFICE; 1978— 757-140 / 66 49

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