EPA-670/2-75-050a
June 1975
Environmental Protection Technology Series
                                                National Environmental Research Center
                                                  Office of Research and Development
                                                         jnmental Protection Agency
                                                             Cincinnati, Onto 45288

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                                          EPA-670/2-75-050a
                                          June 1975
       DIRECT  FILTRATION OF LAKE  SUPERIOR

       WATER FOR ASBESTIFORM FIBER REMOVAL
                       By

      Black § Veatch, Consulting Engineers
          Kansas City, Missouri  64114
           Program Element No. 1CB047
         Contract No. DACW 37-74-C-0079
      Interagency Agreement EPA-IAG-DA-0388
USEPA, Region V and Corps of Engineers, St. Paul
                 Project Officer

                 Gary S. Logsdon
        Water Supply Research Laboratory
     National Environmental Research Center
             Cincinnati, Ohio  45268
     NATIONAL ENVIRONMENTAL  RESEARCH CENTER
       OFFICE OF  RESEARCH AND DEVELOPMENT
     U.S.  ENVIRONMENTAL  PROTECTION AGENCY
             CINCINNATI,  OHIO  45268

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                             REVIEW NOTICE

The National Environmental Research  Center, Cincinnati, has reviewed this report
and  approved  its publication.  Approval does  riot 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
endorsement or recommendation for use.
                                     11

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                              FOREWORD
     Man and his environment must be protected from the adverse
effects of pesticides, radiation, noise and other forms of pollution,
and the unwise management of solid waste.   Efforts to protect the
environment require a focus that recognizes the interplay between
the components of our physical environment -- air, water, and land.
The National Environmental Research Centers provide this multidis-
ciplinary focus through programs engaged in

     •    studies on the effects of environmental
          contaminants on man and the biosphere, and

     •    a search for ways to prevent contamination
          and to recycle valuable resources.

     This report presents the results obtained and conclusions
drawn from pilot plant filtration research for the removal of
asbestiform fibers from drinking water.  The appendices, which are
available separately, present detailed information on water quality,
pilot plant equipment and operation, individual filter run data,
asbestiform fiber and amphibole mass concentrations in raw and
filtered water, and diatomite filter optimization.

     Arrangements for performance of this research were made
through an interagency agreement between EPA Region V and the Corps
of Engineers, St. Paul, Minnesota.
                                       A. W. Breidenbach, Ph.D.
                                       Director
                                       National Environmental
                                       Research Center, Cincinnati
                                 in

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                                 ABSTRACT

Pilot  plant research conducted in 1974 at Duluth, Minnesota, demonstrated that
asbestiform  fiber counts in Lake Superior water could be effectively reduced by
municipal filtration plants. During the study, engineering data were also obtained
for making  cost  estimates for construction  and operation of both granular and
diatomaceous  earth (DE) media filtration  plants ranging in size from 0.03 to
30 mgd.

Both  dual and  mixed-media  granular filters using alum and  nonionic  polymer,
employing flash mix and flocculation  without settling, and DE filters with alum
coated DE as precoat and/or body feed or with Catfloc B added to raw water,
produced effluents  with  amphibole  fiber  counts below electron  microscope
detection limits. Turbidity was not a direct measure of fiber count, but amphibole
counts were generally lowest  at  effluent turbidities sO.l TU.  Chrysotile removal
was more difficult,  but  mixed media  granular filtration with alum and  nonionic
polymer,  and  DE  filtration  with  anionic  polymer conditioned  DE frequently
reduced chrysotile fiber counts markedly.

Systems  for  economic  reasons  recommended  for  consideration  during design
studies are:

1.  Mixed media direct filtration, 5 gpm/ft2, multiple-stage flash mix.
2.  Dual media filtration, 4 gpm/ft2, single stage flash  mix.

3.  Pressure  DE filtration 1  gpm/ft2, alum conditioning of  precoats and body
feed,  or  alum  conditioning of  precoat  only,  and cationic polymer  fed to raw
water.
                                    IV

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                                CONTENTS
Abstract                                                                 ii




List of Figures                                                            iv




List  of Tables                                                            vi




Acknowledgments                                                         viii





Sections




I      Conclusions                                                          1




II     Recommendations                                                    4




III     Introduction                                                         6




IV     Equipment Design, Installation and Operation                           9




V     Sampling and Analysis                                               27




VI     Results                                                             33




VII    Discussion                                                          70




VIII    References                                                         102




IX     Glossary                                                           103




X     Index of Appendices                                                105

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                                FIGURES

No.                                                                  Page
 1       Flow Diagram for MM-1                                         13
 2       Flow Diagram for MM-2                                         14
 3       Alternative Mixing Modes for MM-2                               15
 4       Flow Diagram for BIF (Alt. 1)                                    20
 5       Flow Diagram for ERD                                          22
 6       Raw Water and Effluent Turbidity Curves                          39
         Unit MM-1 Run 31
 7       Raw Water and Effluent Turbidity Curves                          40
         Unit MM-1 Run 32
 8       Head Loss and Effluent Turbidity Curves                          45
         Unit MM-2 Run 107
 9       Head Loss and Effluent Turbidity Curves                          46
         Unit MM-2 Run 109
10       Raw Water and Effluent Turbidity Curves                          53
         Unit ERD-2 Run 47
11       Raw Water and Effluent Turbidity Curves                          54
         Unit BIF Run 25
12       Head Loss and Effluent Turbidity Curves                          55
         Unit BIF Run 110
13       Head Loss and Effluent Turbidity Curves                          56
         Unit ERD-2 Run 79
14       Head Loss and Effluent Turbidity Curves                          57
         Unit ERD-2 Run 21
15       Head Loss and Effluent Turbidity Curves                          58
         Unit ERD-2 Run 34
16       Typical MM- 2 Filtered Water Turbidity Readings                  66
         Obtained with HACH 2100A and HACH 1720 Turbidimeters
17       Typical MM-2 Raw Water Turbidity Readings                      67
         Obtained with HACH 2100A and Monitek Turbidimeters
18       Typical ERD Filtered Water Turbidity Readings                    68
         Obtained with HACH 2100A and Monitek Turbidimeters
                                   VI

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                         FIGURES (CONTINUED)
No.
                                                                        age
19       Typical MM-1 Filtered Water Turbidity Readings                   69
         Obtained with HACH 2100A and Monitek Turbidimeters
20       Relationship Between Raw Water Turbidity at Duluth               71
         Lakewood Intake and ORF Amphibole Fiber Counts
21       Relationship Between Raw Water Turbidity at Duluth               72
         Lakewood Intake and ORF Chrysotile Fiber Counts
22       Relationship Between Raw Water Turbidity at Duluth               73
         Lakewood Intake and NWQL Amphibole Mass Concentration
23       Relationship Between Raw Water Turbidity at Duluth               74
         Lakewood Intake and NWQL Suspended  Solids  Concentration
24       Effluent Turbidity vs. Amphibole Fiber Count                      79
         Granular Media
25       Effluent Turbidity vs. Chrysotile Fiber Count                      81
         Granular Media
26       Effluent Turbidity vs. Amphibole Fiber Count                      85
         Vacuum DE Filtration
27       Effluent Turbidity vs. Chrysotile Fiber Count                      86
         Vacuum DE Filtration
28       Effluent Turbidity vs. Amphibole Fiber Count                      87
         Pressure DE Filtration
29       Effluent Turbidity vs.  Chrysotile Fiber Count                      88
         Pressure DE Filtration
                                   VII

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                                 TABLES

No.                                                                    Page
 1       Dimensions of Unit Process of Granular Filters                     11
 2       Sieve Analysis of Filter Media                                    17
 3       Polymers Utilized in Filter Runs                                  18
 4       Dimensions of DE Units                                          19
 5       Equivalent DE Filter Aids                                        24
 6       Comparative Physical Properties of Amphibole and                  30
         Chrysotile Fibers in Lake  Superior Water
 7       Granular Media Filtration  (MM-1) Summary of Asbestiform          35
         Fiber Removal by Category
 8       Granular Media Filtration  (MM-2) Summary of Asbestiform          36
         Fiber Removal by Category
 9       Number of Runs Made at  or Near Indicated Filter Rate             41
10       Results Obtained Using Dual and Tri-Media Filter Beds              43
11       Relationship of Backwash Solids to Sludge Volume                 47
         Unit MM-2
12       Vacuum Diatomaceous Earth Filtration Summary of                50
         Asbestiform Fiber Removal by Category
13       Pressure Diatomaceous Earth  Filtration Summary of                51
         Asbestiform Fiber Removal by Category
14       Relationship of Backwash Solids to Sludge Volume                 64
         DE Units
15       Granular Media Filtration  (MM-2) Amphibole and                   75
         Chrysotile Removal (ORF Data)
16       Comments on Chrysotile Removal                                 76
17       Granular Media Filtration  (MM-2) Filter Rates                      78
         5 gpm/ft2 and Greater (ORF Data)
18       Vacuum (BIF) and Pressure (ERD) Diatomaceous Earth             82
         Filtration Selected Filter Runs (ORF Data)
19       Water Treatment Plant Economic Analysis — Granular Media         90
         Filtration 30 MGD Plant Design — Lake Superior Intake
         at Lakewood
                                  Vlll

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                         TABLES (CONTINUED)
No.                                                                   Page

20       Water Treatment Plant Economic Analysis - Pressure               92
         Diatomaceous Earth Filtration 30 MGD Plant Design —
         Lake Superior Intake at Lakewood
21       Ranges of Initial Capital Costs of Various Plant                    95
         Capacities Utilizing Granular Media and Pressure
         DE Filtration for Asbestiform Fiber Removal
22       Summary of NWQL Results                                      97
23       Comparison of Amphibole Mass and EM Results in                 98
         Filtered Water Samples
24       Mean  Suspended Solids in Filtrate                               100
                                   IX

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                           ACKNOWLEDGMENTS

 The cooperation and the assistance of the City of Duluth, Minnesota, throughout
 the  pilot filtration study, is gratefully acknowledged. A special thanks is due to
 Mr.  Dave Peterson, Director of Water and Gas, for his help in providing working
 space, electrical power, and other assistance during, the study. Invaluable assistance
 was  also  provided by Mr. Art Biele, Chief  Chemist,  and  Mr. Ted  Olson,  Chief
 Operator, at the Lakewood Pumping Station. Other City personnel assisting in the
 study  were Mr.  Tom Parr, Mr.  Bill  Holmes, Mr. Arvid Benson,  and Mr.  Terry
 Schumann, the pilot plant operator provided by the City.

 The  assistance of several local Federal personnel from the U. S.  Environmental
Protection Agency-National Water Quality Laboratory at Duluth and the United
States  Army Corps of Engineers  at Duluth also is acknowledged. The  laboratory
and  administrative  services  they  provided were  essential to a successful study.
They were:

     Dr. Donald  Mount             National Water Quality Laboratory
                                   Duluth,  Minnesota
     Mr. Mike Lubratovich         National Water Quality Laboratory
                                   Duluth, Minnesota
     Dr. Phil Cook                  National Water Quality Laboratory
                                   Duluth, Minnesota
     Dr. Gary Glass                 National Water Quality Laboratory
                                   Duluth, Minnesota
     Mr. Court Mueller              U. S. Army Corps of Engineers
                                   Duluth, Minnesota
     Mr. Leo Zygmanski             U. S. Army Corps of Engineers
                                   Duluth, Minnesota

The   cooperation and   assistance  of the  following  manufacturers  and  their
representatives  who provided both materials  and  assistance  is gratefully acknow-
ledged :

     Mr. E. E. Halverson            Northwestern Power Equipment Co., Inc.
                                  St.  Paul, Minnesota
     Mr. Clifford  Powell            Johns-Manville Products Corp.
                                  Chicago, Illinois

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    Mr. William Graves

    Mr. Roger Winters

    Mr. Bryce Johnson

    Mr. Bob Miller


    Mr. T. W. Hubner


    Mr. Paul Coffman



    Mr. Dean Newby

    Mr. John  Ebeling


    Mr. Patrick Jayne

    Mr. Don Anspach

    Mr. Henry Mueller
    Mr. Walter Conley
    Mr. Frederick Siegele

    Mr. J. W. HcHugh
Eagle-Picher Industries, Inc.
Minneapolis, Minnesota

Jeno's
Duluth, Minnesota
Johns-Manville Sales Corp.
N. Kansas City, Missouri
Dicalite Division-Grefco, Inc.
St.  Louis, Missouri

Calgon Corp.
Tulsa, Oklahoma

Coffman Industries, Inc.
Builders Iron Foundry
Kansas City, Kansas
Eagle Picher Industries, Inc.
Cincinnati, Ohio
Eagle Picher Industries, Inc.
St. Louis, Missouri

Dow Chemical Co.
Shawnee Mission, Kansas

R.  P. Adams Co.
Buffalo, New  York
Neptune MicroFLOC,  Inc.
Corvallis, Oregon
American Cyanamid Co.
Chicago, Illinois
Builders Iron  Foundry
West Warwick, Rhode Island
The  assistance of  Professor  Walter  Johnson  of  the  University  of Minnesota
involving the loan of a pilot water filter apparatus is sincerely appreciated.
                                     XI

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                                 SECTION I
                               CONCLUSIONS
GENERAL
1.   The  raw water turbidity experienced at the Duluth Lakewood Intake during
the pilot studies ranged from 0.4 to 6.3 TU, but was less than 1.0 TU 90 per cent
of the time.

2.   Heavy rainfall and high  winds  resulted  in  increases of  suspended solids,
turbidity, and  bacteriological  counts  as well  as  changes in  temperature in the
Duluth raw water; however, only high winds, generally from  the east and north-
east, resulted in increases in amphibole fiber concentrations.

3.   A general  link was evident  between the turbidity and the suspended solids
concentration of the raw water from the Duluth Lakewood  Intake.

4.   The  data indicate  a close connection in turbidity readings utilizing a Hach
2100A laboratory turbidimeter, a Hach  1720 in-line  turbidimeter, and a Monitek
in-line turbidimeter.

5.  No discernible tie was evident between the Duluth raw water turbidities and
the asbestiform fiber levels.

6.  At finished water turbidities of less than 0.1  TU,  the  amphibole fiber count
and mass determinations were usually below the detection  limits of the analytical
method used.

7.  A general  association  was  indicated between the  NWQL amphibole  mass
concentration and the ORF amphibole fiber counts in the Duluth raw water.

8.  No  relationship was observed between the counts  of the amphibole and the
chrysotile fibers in the  Duluth raw water.

9.  Proposed  treatment facilities are capable of meeting  the  new Federal  Safe
Drinking Water Act standards which  establish  a  maximum turbidity in  drinking
water of 1.0 TU.

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TREATMENT FOR ASBESTIFORM FIBER REMOVAL

Granular Media Filtration

Based  on achieving BDL or near it,  32 of 34 MM-2 (granular) runs and 21 of 23
MM-1  runs were successful for amphibole removal. Only 8 of 34 MM-2 runs and 2
of 23 MM-1 runs were successful for  chrysotile removal.

Diatomaceous Earth Filtration

For the ERD (pressure)  runs, 19 of 27 were successful for amphibole removal but
only 4 of 27 were successful for chrysotile removal. Vacuum DE filtration (BIF)
was not found suitable for treating the raw water being tested.

TREATMENT FOR TURBIDITY REMOVAL

Granular Media Filtration

1.   Within the range  of  raw water turbidities experienced during the pilot study,
the effluent  turbidity, length of filter run, sludge production,  and asbestiform
fiber removal were more affected by the choice and amount of chemicals than by
the raw water turbidity.

2.   Alum was a more effective coagulant  than ferric chloride in the Duluth  raw
water,  producing lower effluent turbidities  and longer filter runs.

3.   Of the polymers tested in the pilot study, a nonionic polymer, 985N, was the
most effective in preventing turbidity breakthrough.

4.   Resistance to  turbidity breakthrough was greater with two-stage flash mixers
than with in-line  mixers.  Both systems were more effective in terms of filter run
length  and turbidity removal than single-stage mixing.

5.   Sedimentation prior  to filtration  increased  filter run length in proportion to
the amount  of solids  removed in the sedimentation process, but did not increase
fiber removal.

6.   A  sludge production  of approximately 0.03 pound  per  1000 gallons and a
backwash  volume  of  approximately  1.4  percent of the  treated water  resulted
from an average granular  media filter  run.

7.   Amphibole fiber  removal accomplished by the tri-media filter  exceeded that
accomplished by the dual media filters and the DE filters.

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8.   Tri-media filtration  with  two  stage  flash  mixing resulted  in the  lowest
chemical costs.

9.   For  raw  water conditions similar  to those  experienced  during the pilot
studies, granular  filters operated under positive head conditions would minimize
air binding of the filter.

10.  Granular filtration rates  approaching 352  m3/m2  day (6  gpm/ft2) were
effective in the removal of turbidity and amphibole fibers.

11.  The amphibole content of settled backwash wastewater was found to be the
same order of magnitude as that of the raw water.

Diatomaceous Earth Filtration
1.   The vacuum DE unit  was  affected more  adversely by the release of dissolved
gases from the raw water  than the  pressure DE  unit, resulting in turbidity break-
through and  passage of DE through the filter septum.

2.   Total precoat  weights of 0.731 to 0.974 kilogram per square meter (0.15 to
0.2  pound  per square foot) of filter area were required to eliminate high effluent
turbidity and to maintain stability in the precoat.

3.   A  change in grade  of DE in  the body feed application from  fine  to coarse
resulted in an increase in the filter run length  and higher effluent turbidities.

4.   The rate of head loss buildup and length of filter run in the DE units were
affected more  by the type  of precoat and the type and  amount  of DE and
chemicals in the body feed process  than by the turbidity of the raw water.

 5.   A  medium grade  precoat  and   a  fine grade  body feed were most effective in
turbidity and asbestiform fiber removal.

 6.   For the Duluth  raw water, two treatment conditions, alum and  soda  ash
 added to the precoat with a cationic polymer introduced  to the raw water, and an
 anionic polymer  added to the precoat,  were  most  effective in  turbidity and
 asbestiform fiber removal.

 7.  Although an optimum flow rate of 94 m3/m2 day (1.6 gpm/ft2) is theoreti-
 cally  obtainable, the  rate  of  60 m3/m2 day (1.0 gpm/ft2) as  employed in the
 pilot study will result in substantial turbidity and asbestiform fiber removal.

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                                 SECTION II
                            RECOMMENDATIONS
 GENERAL
 1.   Quality  control of  the  filter  operation  should  be based on  maintaining  a
 finished water having a turbidity not greater  than 0.1  TU.

 2.   In-line turbidimeters should  be used for continuous monitoring of the raw
 and finished  water turbidity.

 3.   Electron microscope analysis  for  asbestiform fiber  counts should be per-
 formed periodically on raw and finished water samples to check on the effective-
 ness of the treatment processes for fiber removal.

 4.   Analysis for amphibole mass by X-ray diffraction in raw and  finished  water
 should  be  performed more frequently  than  electron microscope analysis due to
 the lower costs and more rapidly obtainable results involved.

 5.   Costly and time-consuming electron microscope analysis for asbestiform fiber
 counts  should  be replaced by  improved analytical techniques as  soon as they
 become available.

 6.   For large capacity  plants, granular  filtration of Lake  Superior water  is re-
 commended  over  diatomaceous earth  filtration. For  small plants, diatomaceous
 earth filtration should also be considered.

 GRANULAR MEDIA FILTRATION

 1.  Two stage  flash mixing followed by flocculation is recommended for  condi-
 tioning the raw water prior to filtration.

 2.  A positive  head tri-media filter designed to operate at a rate of  290 m3/m2
              ^
day  (5  gpm/ftz) at design flow is recommended.

3.  For  treatment of Lake Superior water at  the Duluth Lakewood Intake, alum
at 12-20mg/l and 985N or an  equivalent nonionic polymer  at 0.05 mg/1  is re-
commended when the raw water turbidity is near 1.0 TU.

4.  Although sedimentation is  not required  for fiber removal, presedimentation
could be used to reduce  the solids  loading to the filters and to extend filter run
lengths.

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5.  Provision  should  be made for the introduction  of polymer to  the  flash
mixers, the flocculation chambers,  the filter beds, or to  any combination of the
three  locations.  In addition, provision  for the  addition of a  second polymer
should similarly be made as a potential aid in chrysotile removal.

6.  Backwash wastewater should be discharged to a sludge lagoon, with return  of
the supernatant to the treatment plant.

D1ATOMACEOUS EARTH  FILTRATION
1.  For the conditions experienced during the pilot studies, pressure DE filtration
is recommended with provisions for addition of chemical aids to the precoat, the
body  feed, and the raw water.
                                                                      O   n
2.  The DE filters should be designed for a flow rate of approximately 60 m /m
day (1.0 gpm/sq ft2).

3.  A medium grade DE at approximately 0.974 kilogram  per square meter (0.2
pounds per  square foot) of filter  area coated with alum at O.Olg/g of DE and
soda  ash at  0.005 g/g of DE and a cationic polymer at 0.5 mg/1  added to the raw
water or  an equal grade and  amount of DE coated with an anionic polymer  at
0.00005  g/g  of DE should  be  used for precoating for treatment of Lake Superior
water at  the  Duluth Lakewood Intake.

4.  A fine grade of DE at  a rate of 20 to 30 mg/1 should be used for body feed
for treatment of Lake Superior water at  the Duluth Lakewood Intake.

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                                 SECTION III

                               INTRODUCTION
 PURPOSE OF STUDY
 The pilot filtration study  was conducted  to determine which  of the  filtration
 systems  studies was most effective  in  the  removal of asbestiform fibers, and to
 obtain for each system the necessary data for design of a full-scale water treat-
 ment plant. Data to be obtained included raw and  filtered turbidities, asbestiform
 fiber removal  efficiencies,  length of  filter run, rate of head loss buildup,  and
 sludge produced per 1,000 gallons (gal) of water treated.

 BACKGROUND

 Prior to initiation of the pilot filtration study, little was known about the removal
 of asbestiform fibers from  water. However, studies  conducted by  the  Corps of
 Engineers did  indicate  a  substantial portion  of the  asbestiform fibers  could  be
 removed  from the  water  using  pressure  diatomaceous earth  (DE) filters.  In
 addition,  studies at the U. S.  Environmental Protection Agency (EPA) laboratory
 in Cincinnati indicated  that granular filters  could also effectively remove much of
 the asbestiform fibers from  the water. The selection of granular and DE filters for
 testing during  the  pilot  filtration study was made  on  the  basis  of  the work
 conducted by the U. S.  Army  Corps of Engineers and  the EPA.

 SCOPE OF STUDY

 During the  period  from April through September, 1974, four pilot filter units
 were operated in Duluth, Minnesota, on Lake Superior water. The primary goal of
 the pilot  filtration study was  the  investigation of the ability of various  filtration
 systems  to  remove  the  asbestiform fibers and  turbidity found  in  the water
 supplies of the Duluth-Superior-Cloquet area,  with  emphasis on removal of fibers
 and  turbidity from the raw water obtained at the Lakewood Intake in Duluth,
 Minnesota. Filtration  processes investigated  included  granular  filtration, pressure
 DE filtration, and  vacuum DE filtration. The study  was originally scheduled to be
 completed after a period of  4 months,  but results obtained  during this  period
indicated  further  study would be beneficial. The study was  therefore  extended
 for  5  weeks, with additional variables  in operation investigated,  especially  to
increase the removal of chrysotile fibers. A total of 227 granular filter runs and
 228  DE  filter  runs were conducted. Limitations of  time and money prevented
study of  other methods  of water treatment which might have been considered.

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Variables studied during the pilot plant operation are summarized below:

ELEMENTS OF STUDY
Granular Media Filtration
 1.  Filtration with and without prior sedimentation.
 2.  Effectiveness of combinations of iron salt and polymers and aluminum salt
     and polymers.
 3.  Dual media versus tri-media filter bed.
 4.  Effect of filtration rate.
 5.  Rate of head loss buildup.
 6.  Sludge production.
 7.  Effect of seasonal conditions.
 8.  Effect of raw water turbidity on filter  performance.
 9.  One-stage versus two-stage flash mixing.
 10.* Flash mixing chambers versus in-line mixers.
 11.* Techniques for increased removal of chrysotile as well as amphibole fibers.
 12.* The effect of higher raw water algal  counts on  filter performance (no algal
     blooms occurred).

 Diatomaceous Earth Filtration
  1.  One-step versus two-step precoating.
  2.  Effect of body feed concentration.
  3.  Addition of chemical aids to precoat and/or body feed.
  4.  Rate of head loss buildup.
  5.  Sludge production.
  6.  Effect of seasonal  conditions.
  7.  Effect of raw water turbidity on filter performance.

 *  Variables studied during the 5 week extension.

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  8.* Techniques for increased removal of chrysotile as well as amphibole fibers.




  9.* The effect of higher raw water algal counts on filter performance.




 10.* Generation of adequate data for input to the POPO computer program.
* Variables studied during the 5 week extension.

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                               SECTION IV
          EQUIPMENT DESIGN, INSTALLATION, AND OPERATION

GENERAL
The pilot filtration  study was conducted with two granular filters and  four DE
filters installed at the Lakewood  Pumping  Station in Duluth, Minnesota.  The
granular  filters were a skid-mounted and a trailer  mounted  "WATER-BOY"  unit
as manufactured  by Neptune MicroFLOC,  Incorporated,  Corvallis, Oregon.  The
DE filters were two pressure DE units supplied by the Corps of Engineers and
two  vacuum DE units  as manufactured  by  the  BIF  Corporation,  Providence,
Rhode Island.

RAW  WATER SOURCES
With the exception  of three runs on  the MM-2 units, all runs on the pilot filtra-
tion units were made using the Lakewood wetwell as the raw water source. The
intake of the  Lakewood Pumping  Station extended approximately  1,500ft out
into  Lake Superior and  was  about 70 ft below the surface of the lake. Suction
hoses were placed directly in the wetwell and raw water was pumped to each of
the filter units so that the raw water  supplied to  the units  was the  same as that
being supplied to  the City of Duluth.

Raw water from the Cloquet Pipeline  Intake was used for three runs on the MM-2
units.  The  Cloquet raw  water was  transported  from  the Cloquet raw water
pumping station on  Minnesota Point to the Lakewood Pumping Station in a 4,800
gal tank truck. After the truck arrived at Lakewood,  the suction of one of the
pilot plant raw water pumps  was connected  to the discharge from the tank truck
and the  water pumped  to the MM-2 unit.

PERSONNEL
The  operation of the pilot  filtration  systems was conducted by three  operators
and a field engineer. The pilot  filters  were operated in 8-hour  shifts, 24 hours  a
day, 5 days a week for a period of 5 months extending from  April 19, 1974 to
September 20, 1974. The study was conducted in three phases:

1.  A preliminary  test  phase  to train the  operators, develop testing and  data
recording procedures, and gain plant  operating experience.

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 2.   A treatment efficiency phase  to  determine which  treatment  methods  gave
 promise of effectively removing asbestiform fibers from the raw water.

 3.   An  "optimum-design"  phase.  The operation of the  DE  filters during this
 phase  was conducted to determine filter cake resistance measurements necessary
 for  optimum design  of  DE filters to  provide  least cost of  filtration of Lake
 Superior  water. The granular filters were operated during this  phase with several
 variations in  the physical  set-up of the filter systems to determine the best process
 scheme for asbestiform fiber removal.
AMBIENT CONDITIONS

To determine  if any relationship existed  between  ambient conditions and the
quality of the raw  water  at the  Lakewood Pumping Station, daily records were
maintained on temperature, wind velocity  and direction, precipitation, and  lake
level.  The daily  temperatures  and wind  velocities and  directions were obtained
from records kept by the operators at the Pumping Station.  The Pumping Station
records are  not official, but because  of the wide discrepancy between weather
conditions at the Pumping  Station and the National Weather Service Station, it was
decided that the unofficial records would better represent the conditions at the
Pumping  Station Intake. No  record of  precipitation was kept at the Pumping
Station. Therefore, official National Weather Service data were used for precipi-
tation values. Lake level data were obtained from the  Corps of Engineers station in
Duluth, and are based on  International Great Lakes  datum.  Records of tempera-
ture,  wind velocity  and direction, precipitation, and lake level are presented in
Appendix A-l.

A record  was also maintained of the Lakewood raw water  pumping schedule. This
record is presented in Appendix A-2. All data in the tables refer to Pump No.  2 as
this was the only raw water pump which the City operated during the course of
the pilot filtration study.
GRANULAR UNITS

Because  the  turbidity  of  Lake Superior  water is  generally low  and  in  such
circumstances  direct  filtration  has  been  found to  be successful  for  turbidity
removal, this  process  was tried  for fiber  removal.  In direct filtration, water  is
conditioned with an  inorganic coagulant  and polymer  and  filtered  (usually
                                      10

-------
through dual or mixed media) without sedimentation.  Selection of the particular
granular media used was  based  on the wide  and successful experience with the
media chosen.

Size and Type
The two  granular units used  in the filtration study were designated as MM-1 and
MM-2. The only difference in the basic set-up  of the two filters was in the size of
the settling basins. MM-1  had a  settling basin  with a volume of 1,708 liters (451
gal) and MM-2 a settling basin with a volume of 693 liters (183 gal) allowing for
approximately 30 centimeters of freeboard at  the design rate utilized. Dimensions
of each of the granular units are presented in Table 1. Further details appear in
Appendices B-l and B-2.

TABLE 1.    DIMENSIONS OF UNIT PROCESSES OF GRANULAR FILTERS
Pilot Unit
MM-1
Mixing chamber
Flocculation chamber
Sedimentation chamber
Filter chamber
Clearwell
MM-2
Mixing chamber
Two-stage mixing chamber0
Kenics mixers
Flocculation chamber
Flocculation chamber0
Sedimentation basinc
Filter chamber
Clearwell
Length
cm

62.2
65.5
154.2
62.7
-

62.0
—
52.7
62.0
152.4
152.4
62.2
152.4
Width
cm

29.5
62.2
91.2
62.2
137.93

29.2
—
5.08a
61.5
30.0
30.0
62.0
91.4
Depth
cm

182.9
182.9
Varied 163 to
182.9
152.4

184.2
—
—
184.2
Varied 157 to
Varied 157 to
184.2
177.8




183







178
178


a  Diameter rather than width.
b  208 liter (55 gal) drum.
c  Used for flocculation on all runs except Run 140.

Mixing and Settling Variations

A  flow diagram of the MM-1  (granular) unit is presented on Figure 1. Raw water
entered  the  flash-mixing  chamber of the unit where the  coagulant was added.
Detention time in the mixing chamber was  5.1 minutes (min) at a nominal flow
rate  of  87  cubic meters per day (m^/day), or  16 gallons per  minute (gpm).
                                     11

-------
Calculation of  all detention  times  was  based on flow rates and unit volumes.
From  the  mixing  chamber, the  water entered the flocculation chamber where
the polymer  was  added.   With  sedimentation,  the   polymer   was  added at
the entrance to  the  sedimentation  chamber  (Figure 1).  Detention  time in the
flocculation chamber was  12.3  min.  After flocculation,  the water was discharged
either  into the sedimentation basin  or directly onto the filter, depending upon
which  mode of operation  was being used. A dual media  filter bed with  an
effective surface area of 0.37 square  meter (m2), or 4 square feet (ft2) was used in
all runs  conducted with the MM-1  unit. Flow through the filter bed was main-
tained  at a constant rate by a float valve located on the effluent discharge line. A
water  meter  was  installed in  the effluent  line to  determine the rate  of flow
through the unit and the total volume of water treated during each run.

Sedimentation ahead of the filter was provided by removal of a bypass line and
installation of tube settlers in the sedimentation chamber. The tube  settlers were
hexagonal-shaped,  installed on  a slope of 5  degrees, with a  diameter of 2.54 cm
(1 in)  and  a  length of 1.2 meters  (4 ft).  A  detention time of approximately
28 min was provided in the sedimentation chamber at a nominal flow rate of 87
m3/day (16gpm).

Flow  diagrams  of the MM-2 (granular unit) are presented on Figures 2 and 3. Raw
water  was introduced  into one of  several  points described  below for chemical
mixing:

1.  A flash mixing chamber.
2.  A sequence of two  208 liter (55  gal) external flash mixing drums.
3.  A sequence of Kenics  in-line static mixers external to the  unit.

The flash mix chamber provided a detention time of 5.0 min at a filter rate of 87
m^/day (16 gpm). Flow from the  flash mix chamber was discharged into a floc-
culation  chamber, with a  detention  time of 10.3 min, where  the polymer was
added.

For the sequential backmix system, flash  mixing occurred in two steps in two 208
liter (55 gal) drums. The  primary coagulant was added  at Point C, (Figure 3)and
the polymer  was added at Point  D  (Figure 3).  At  a  filter rate  of 87 m^/day
(16 gpm),  the  theoretical detention  time was  2.8 min in  the first drum and 2.2
min in the second drum.  When three treatment chemicals were used  in sequence,
the third was added at  Point D  (Figure 2).
                                     12

-------
   -FROM LAKEWOOD
    WETWELL
           FLASH MIXER

                  FLOCCULATOR  DRIVE
                          FLOAT VALVE TO
                          CONTROL  FLOW
                          THRU FILTER
-THROTTLING
 VALVE
BACKWASH
TO WASTE
                                    FILTER
                                    MEDIA-
                                                  HOSE BIBB TO
                                                  MONITEK
                                                  TURBIDIMETER
O                            WATER  METER
                             THROTTLING
                             VALVE

                             .
                            TUBE
                            SETTLERS
BACKWASH
VALVE
                                                                     ''OVERFLOW
                                                                     TO WASTE
                                                EFFLUENT  PUMP
                                                          BACKWASH PUMP
 MIXING     FLOCCULATION SEDIMENTATION
 CHAMBER      CHAMBER        BASIN
                              FILTER
                                BED
                        CLEARWELL
                 FIGURE   I  . FLOW DIAGRAM FOR MM-I.

-------
  FLASH
  MIXER
   FLOCCULATOR
   DRIVE
                                              WATER METER
COMPRESSED
AIR-
         FLOAT VALVE TO
         CONTROL  FLOW
         THRU FILTER
                                    FILTER
                                    MEDIA"
                              BACKWASH
                              TO WASTE
                           BACKWASH
                           VALVE
  /HOSE BIBB TO
( HACH IN-LINE
1  TURBIDIMETER
?
    RAW WATER
                                                                        Cm/i
                                                           OVERFLOW
                                                           TO WASTE
                                                              EFFLUENT  PUMP
                                                          BACKWASH PUMP
    MIXING
   CHAMBER
(SEE  FIGURE  3
FOR ADDITIONAL
MIXING MODES)
FLOCCULATION FLOCCULATION    FILTER
  CHAMBER     CHAMBER        BED
                             CLEARWELL
                   FIGURE  2   . FLOW  DIAGRAM  FOR MM-2.

-------
1725 RPM MIXER-)      TO  FLOC
                    CHAMBER
                                         TO  FLOC  CHAMBER
rl fZJ) NPM MIXEK1

X]      D
"t
^a

9

1
^a

9
.TO FLOC
/CHAMBER
V
 55 GALLON  DRUMS'

RAW  WATER
                  KINECS CORP.
                  STATIC MIXER
                       RAW WATER
                                         KINECS  CORP.
                                         STATIC  MIXER
                                          RAW WATER
                                              XXHX
      FIGURE 3   .ALTERNATIVE MIXING  MODES FOR  MM-2 .

-------
With the sequential in-line  mixing, shown on Figure 3, a combination of three or
six  5.08 cm (2 in) diameter Kenics static mixers were used. Provision was made
for  adding up to three different treatment chemicals at  Points E, F, and  G.
Mixing  of water  and chemical occurred in  either one or two mixers before the
next chemical  was added. At a filter flow rate of 87  m^/day (16gpm), the
detention time in each static  mixer module was 1.1 seconds.

Flow  from the mixing portion of the  process was discharged into a flocculation
chamber, with a detention time  of  10.3  min  at  a filter rate  of 87  m^/day,
(16 gpm).  An  additional 11.4 min of flocculation was provided by removing the
tube settlers from the sedimentation chamber of the MM-2 unit and bubbling air
up through the flow  as it passed through the chamber.

From the  sedimentation chamber, the  flow was discharged  onto the filter. A dual
media  filter bed was used in 76  runs and a  tri-media   filter  bed  in  64 runs
conducted with the  MM-2 unit.  The filter  bed  had an effective surface area of
       9     9
0.37 mz (4  ftz). Flow through the filter was maintained at  a constant rate by a
float valve located on the effluent discharge  line. A  water  meter  was installed in
the effluent  line to establish filter flow rates and  to determine the total volume of
water treated during  each run.

Filtration Rates

All  runs on  the MM-1 unit were  conducted at a flow rate  of approximately 232
                                     o   9
cubic meters per square meter day  (nr/mz day), or 4 gallons per minute   per
square  foot (gpm/ft2).

Most of the runs on the MM-2  unit were conducted at a flow rate of approxi-
              -3  ^               s-\
mately  232  m /m   day (4 gpm/ft  ). However, to determine the effects of flow
rate on the  performance of the filter,  14 runs were  conducted  at a  flow rate of
approximately 290 m3/m2 day (5  gpm/ft2), 3  runs at about  116  m3/m2 day
(2 gpm/ft2), and 22  runs at approximately 350  m3/m2 day  (6 gpm/ft2).

Media  Description

The results of a sieve analysis on the various medias and the composition of the
dual and tri-media beds  used during the pilot  study are given in Table 2.
                                     16

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TABLE 2.     SIEVE ANALYSIS OF FILTER MEDIA3
Media
Anthracite
Brady sand
Fine illmenite
Coarse illmenite
Very coarse illmenite
Effective Size
mm
1.10
0.42
0.22
1.02
1.75
Uniformity
Coefficient
1.60
1.52
1.66
1.55
2.06
Media
Thickness
Dual Media Tri Media
cm cm
53.3
22.9
—
--
—
41.9
22.9
11.4
3.8
3.8
a Analysis performed by Neptune MicroFLOC, Incorporated.


The dual media bed was used for all runs on MM-1 and  76 runs on MM-2 and was
placed directly on the carborundum filter bed supports provided with each of the
granular units. The tri-media bed was used for the last 64 runs en the MM-2 unit.
To  insure that none  of the fine illmenite  would pass  through the  carborundum
support,  two coarser  sizes of illmenite were placed on  the carborundum  support
prior to installation of the bed.

The  dual media beds were installed under the  supervision and  direction of  a
representative of Neptune MicroFLOC,  Inc.  The tri-media bed was installed by
the field  engineer with assistance from the pilot plant  operators. The placement of
the beds was accomplished by  adding  an  excess of the bottom layer of media,
backwashing the  filter, skimming  about one-half the  excess media off,  back-
washing again and skimming off the remainder of the excess media. This procedure
was repeated for each media.

Chemical Additions
Alum  and ferric  chloride (FeCl-^)  were used as the primary coagulants in  the
testing of the granular  filters.  The  coagulant solutions were mixed daily at  the
pilot plant site to a 1.19 percent solution  strength using dry chemicals and raw
water from the Lakewood Intake.

The polymers used in the pilot filtration study were selected partially on the basis
of availability and partially on the  basis of jar tests  conducted at the Lakewood
laboratory. The  polymers utilized in the  filtration study are presented in Table 3.
                                     17

-------
TABLE 3.     POLYMERS UTILIZED IN FILTER  RUNS
Polymera
A-23
847A
Separan NP-10
Catfloc B
C-31
573C
985N
N17
Type
Anionic
Anionic
Weak Anionic
Cationic
Cationic
Cationic
Nonionic
Nonionic
Manufacturer
Dow
Cyanamid
Dow
Calgon
Dow
Cyanamid
Cyanamid
Dow
Home Office
Midland, Mich.
Chicago, 111.
Midland, Mich.
Pittsburg, Pa.
Midland, Mich.
Chicago, 111.
Chicago, 111.
Midland, Mich.

a Each of these polymers is  approved by the EPA for potable water use.


The liquid  polymers were  generally mixed for at least 30 min before use and the
powdered polymers were mixed in excess of 1 hour before use.

Backwashing

Backwashing  of  the granular units  was initiated for one of two reasons,  either
excessive head loss through  the  filter  or   excessive   effluent   turbidity. If
effluent quality  was satisfactory, the filter was backwashed whenever  the  head
loss  through the  filter  exceeded  8 ft of  water.  Effluent  quality controlled
initiation of the backwash cycle whenever the turbidity exceeded 1.0 TU or the
turbidity of the  raw water, whichever was lower, or whenever it became evident
that turbidity breakthrough had occurred. Turbidity breakthrough was evidenced
by a sudden and continuous rise in effluent turbidity readings.

A water only backwash with no surface wash was used for cleaning the granular
unit filter bed. To determine the amount of backwash water used and the rate of
backwashing, the length of backwash, and the level of water in the backwash tank
before and after each backwash cycle were recorded. Backwashing rates and length
                                                "30               0
of backwash  varied,  but were  usually about  755 m^/m  day (13gpm/ftz)  and 7
min respectively.

DIATOMACEOUS EARTH UNITS

Four  DE filter units were installed  at the pilot plant site, two vacuum filters and
two pressure  filters. Both vacuum and pressure units were installed to determine if
                                     18

-------
release  of dissolved  gases under vacuum conditions would be detrimental  to the
filtration  process. Although two vacuum filters were installed, only one was used
for the pilot study, with  the second filter  provided as  a standby  unit.  The
vacuum DE  filter was designated  as the  BIF unit. The pressure DE filters were
designated ERD-1 and ERD-2,but  the two pressure filters were identical and all
data and  discussion  will  be  presented under the heading ERD. The dimensions of
the units are given in Table 4.

TABLE 4.    DIMENSIONS OF DE UNITS
Pilot Unit Length
cm
Width
cm
Depth
cm
BIF
   Filter section            78.7          20.32            Varied  72.4 to 76.2
   Raw water tank           -           68.6a                    92.7
   DE slurry or polymer tank -           35.Oa                    50.8
ERD
   Water treatment section    -     Varied 67.3 to 221.03         147
   Filter section             -     Varied  7.6 to  40.6a         137
   DE slurry or polymer tank -           61.0                     91
a Diameter rather than width

Vacuum  Unit

A flow diagram of the BIF unit is presented on Figure 4. Raw water entered the
mixing chamber where  chemical  or body feed additions, if any, were made and
mixing was accomplished. The water level in the mixing chamber was controlled
by a float valve installed  on the influent raw water line. Dry body feed was added
by  a  helix feeder.  If alum-coated  body feed was  being  used, a  DE  slurry was
mixed  in a slurry tank and fed to the mixing chamber.  From the mixing chamber,
the water  flowed into  the filter section  of  the unit where  the water passed
through the filter elements due to suction  from the effluent pump, and was dis-
charged into the waste sump. The filter had an  effective  surface area of 0.93 m^
     T
(10ftz).  A water  meter was installed  in  the  effluent line to set  flow rates and
determine the total amount of water treated during each run.
                                     19

-------
Isi
O
      FINISHED
      WATER
       WATER
       METER
       HEADLOSS
                             ^-
                            f
TEN SQ.FT.
DE FILTER
                           -0*3-
                             •BODY FEEDER
                                        •475 RPM
                                        MIXER
                                       HOSE BIBB FOR
                                       BACKWASH-
                                              RAW
                                              WATER
                                       DRAIN TO WASTE
                                       VRAW  WATER PLUS
                                        BODY  FEED
                                 ^RECIRCULATION  LINE
                 •EFFLUENT AND
                 RECIRCULATION PUMP
                                        ^VALVE  CONT-
                                          ROLLED BY
                                          WATER LEVEL
                                          IN  TANK
                                      ^DRAIN TO WASTE
                      FIGURE  4   .FLOW  DIAGRAM  FOR BIF(ALT.I)

-------
Pressure Unit
A flow diagram of the ERD unit is presented on Figure 5. The unit consisted of a
water  treatment  section,  a filter  section,  and  a drain  tank. The water treatment
section was designed to remove organic and suspended matter in the raw water to
a level suitable for further treatment in the filter section.  However, the quality of
the raw water at the Lakewood Pumping  Station was such that treatment of the
water  ahead of  the filter section  was not considered necessary.  Therefore,  no
coagulants were  added in the water  treatment  section.  Because of the piping
configuration of the unit, water did  flow through this section.

Each  DE  filter was a two-part cylinder containing six cylindrical elements, with
                                                      9         9
each element having an effective surface area of 0.15 rcr  (1.67 ftz),  providing a
total  filtration area of 0.9 m^  (lOft^) per filter. Each filter was equipped with
gages  for  indicating influent and effluent pressure, a precoat funnel, an air release
valve, and a rate of flow controller in the effluent discharge line.

Filtration Rates
All runs on the BIF and ERD units were  made at a flow rate  of approximately
     ^  0              "~)
58 m  /m   day (1 gpm/ft  ), using raw water from the Lakewood Intake, and were
made without sedimentation prior to filtration.

Precoat Methods

Although  the  ERD  unit is a pressure  type filter and the  BIF unit a vacuum type
filter, the principle of operation for the units is essentially the same. DE filtration
as conducted during the pilot filtration study consists of three basic steps:

1.  Precoating
2.  Filtration
3.  Backwash

The purpose of the precoat  is to give  immediate clarity and to prevent the filter
septa  from becoming clogged by impurities contained in the raw water. Precoating
is accomplished by circulating a  slurry of DE through the filter  septa.   Since
most  of the DE particles  are  larger than  the openings  in the filter  septum, they
form  a precoat by  bridging these openings. After the precoat  is formed on the
filter septa, the filtration process is begun by positioning appropriate valves on the
unit from the recirculation to  the filter position,  and initiating body feed to the
flow of water.  This normal precoat procedure was altered somewhat when it was
                                     21

-------
                                             RECIRCULATION  LINE
    BODY FEEDER-*
                   r
UPFLOW CLARIFIER
    TO MONITEK
 RAW WATER-
                  -M-
                            EDUCTOR
            AIR  RELEASE
            VALVE
  FILTER PUMPH
TO BIF
•FILTER WASH
 VALVE
                                                             PRESSURE
                                                            kGAGE
                                                                 FILTER
                                                                 RECYCLE
                                                                 VALVE
                                -TO WASTE
                                SUMP
                                     FINISHED WATER
                                                                RATE  OF
                                                                FLOW
                                                                CONTROLLER
                                            FLOW METER
            FIGURE  5  . FLOW DIAGRAM FOR  ERD (ALT. I)

-------
discovered early  in  the  research through analysis that a portion of the DE was
passing through the filter into the  treated water. A two-step precoating procedure
was initiated in an effort to eliminate the DE bleed-through. The procedure when
precoating in two steps was similar to  that used when  precoating in one-step
except that two  DE slurries were mixed,  one using a  coarse DE and one using a
fine  DE.  After  mixing  the two slurries and filling  the filter  section with raw
water, the recirculation  pump was started and the coarse  DE slurry poured into
the filter  section. The unit was placed  in recirculation until the  water cleared and
then the fine DE slurry was poured  into the filter section. The  unit continued to
recirculate until  the water  once again cleared, at which  time the recirculation
valve  was closed  and the effluent valve opened to  the position  giving the desired
flow through the filter  unit. Bleed-through  of DE through the filter septa was
discovered during the first week of testing. The two-step precoat method utilized
was successful in eliminating the  bleed-through problem.

Body Feed

The purpose of the body feed is to  maintain the permeability  of the filter  cake.
The  amount of  body feed  added  is dependent  upon the  concentration  of sus-
pended solids  contained in  the  raw water and must  be carefully  controlled to
achieve the  maximum  filter cake permeability.  Too much  DE relative to the
suspended solids  concentration will add excessive  thickness to the filter cake and
reduce the cake  permeability. Too little DE  will  not  sufficiently offset the effect
of the raw water suspended solids, and will either allow breakthrough of solids or
result in a reduction in the filter  cake permeability.

DE Filter Aids

DE filter aids are  produced by several  manufacturers in  several  grades. Table 5 lists
the filter  aids utilized in the pilot  filtration study. The table lists the trade name
of filter aid grades  from several manufacturers that are "equivalent". Filter aids
are considered  "equivalent"  when they produce approximately the same  flow rate
and clarity under the same operating  conditions.
                                     23

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TABLE 5.    EQUIVALENT DE FILTER AIDS
Brand Name
Celatom FW-6a

Celatom FW-12a
Celatom FW-20a
Celatom FW-50a
Celatom FW-60a
Mean Particle
Size
urn
6

8
12
15
19
Structure
Flux
Calcined
Flux
Calcined
Flux
Calcined
Flux
Calcined
Flux
Calcined
Equivalent Filter Aid
Celite 5126
Special Speedflowc
Hyflo Super Celb
Speedplusc
Celite 503b
Speedexc
Celite 53 5b
4200C
Celite 545b
4500C
a Manufactured by Eagle-Pitcher Industries, Inc.
 Manufactured by Johns-Manville Products Corporation.
cManufactured by Dicalite Division Grefco, Inc.

DE Conditioning

Modifications made in the operation of the DE units  during the course of the
pilot filtration study to enhance asbestiform fiber removal included:

1.   Addition of chemical aids to the precoat
2.   Two-step precoating
3.   Addition of chemical aids to the body feed
4.   The addition of polymer along with body feed into the raw water

Runs made  with a single  precoat  and no chemical  aids in the  precoat or body
feed did not have satisfactory finished water turbidities. In an attempt to lower
the effluent turbidities, an anionic or cationic polymer was added to the precoat.
The precoat procedure when polymer was  used in  the precoat was unchanged
from the  above  except that  polymer was added to  the DE slurry prior  to  pre-
coating. The anionic  polymer was added  to  the DE slurry as a 0.01 per cent
solution and from 0.00001 to 0.00005 gram of polymer per gram of DE (g/g DE)
                                     24

-------
was added. The cationic polymer was added as a 0.1 per cent  solution and from
0.0003 to 0.0006 g/g DE was added.

Several two-step precoats were made using a  chemical aid in both the coarse and
fine  steps. Polymers  were added to the  precoats in the same manner as when  a
single precoat was used. Alum was  added to the precoats as a 5 per cent solution
and from 0.01 to 0.11 g/g DE was  added. In addition,  whenever alum was added
to the precoats, sufficient  soda ash, partly purified sodium  carbonate, was added
to prevent depression of the  pH to a value lower than  7.0. To allow time for alum
coating of the DE, the alum, soda  ash, and DE were added  to 3.78  liters (1 gal)
of water, the mixture was stirred, restirred after 5 min of quiescent settling, again
restirred  after another 5 min of  quiescent settling, and then  poured into the filter
section.  All  other  steps in  the  precoat  procedure were  the same as  previously
described in this section.

The  use  of chemical  aids in  both precoats sometimes resulted  in plugging of the
filter  septa.  To  prevent  plugging,   the  chemical   aid  was  added  only  to   the
second precoat, with  the first precoat being used as  a  protective coat for the filter
septa.

Backwashing

As the permeability  of the filter cake  decreased, the  head loss through the filter
increased until it reached a point where the unit must be backwashed. To control
the operation of the  filters,  the  turbidity of the raw and finished  water  and the
head loss through the filters  were recorded hourly for each of  the DE units. The
total  head loss through the  filter which could  be tolerated varied due  to several
factors, with one of  the more important being type of filter system  used, i.e., a
pressure  or a vacuum system. A pressure system  could be operated at a much
higher  pressure differential than  a vacuum system. During the backwashing of the
unit, the DE, including the precoat, was completely flushed from the  filter septa.
The unit was then ready for  a subsequent precoat-filtration-backwash  cycle.

Backwashing  of the units was initiated for one of three reasons:

1.  Excessive head loss through the  filter
2.  Excessive effluent turbidity
3.  Time limitations
                                      25

-------
 If effluent quality was satisfactory and  the length of filter run had not exceeded
 24 hours, the BIF  unit was backwashed when the head loss through the filter
 reached  17 ft of water (7.5 psi).

 If effluent quality was satisfactory and  the length of filter run had not exceeded
 24 hours, the  ERD  unit  was backwashed when  head loss  through the  filter
 reached  103 ft of water (45 psi).

 At the beginning  of the pilot filter study, if the turbidity of the finished water
 exceeded 1.0 TU  or the  turbidity of the raw  water,  whichever was lower, the
 units  were backwashed regardless of head loss or length of filter run. However, as
 the study progressed, it was decided  that  a lower limit on  effluent turbidity was
 necessary and during the last  6 weeks of the study, the units were backwashed
 whenever the effluent turbidity exceeded 0.20 TU.

 If the effluent turbidity was satisfactory and the  head  loss  through the units had
not reached terminal limits within 24 hours, the units were backwashed  due to
time  limitations. It  was believed that any useful data which could be obtained
from  a  particular  run would be  obtained within this  period  and  that  any
extension of run length would not  be beneficial.
                                    26

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                                SECTION V

                        SAMPLING AND ANALYSIS

SAMPLING

A  1 liter grab sample of raw water and treated water from each unit was collected
during each 8-hour  shift for analysis in  the  laboratory at the Lakewood Pumping
Station. Color,  pH,  alkalinity,  hardness,  odor, and temperature were  run on each
sample and  certain  samples  were  also  analyzed for  aluminum and iron  to
determine  if there  was any  carryover of  coagulant  into  the treated  water.
Aluminum content  was analyzed  to determine the amount  of alum which passed
through the filters as a measure of treatment effectiveness. Grab  samples of treat-
ed water were  taken during periods when coliform counts in the raw water were
high to determine the efficiency of the units in removing bacteria. When problems
occurred with air binding of the  filter units, samples were collected to determine
the dissolved oxygen content of the water.

Backwash water samples were  collected  from Run 43 and all subsequent runs on
MM-2, and Run 14 and all subsequent runs on MM-1. Depending  upon  which
mode of operation  was  being used, i.e., sedimentation  or no sedimentation, the
backwash sample was collected either from above the filter bed and also the drain
from  the sedimentation basin, or only from above the filter bed. Most backwash
samples were collected by grabbing  a portion of backwash water  at the  beginning,
the middle, and near the end of the backwash cycle. However, subsequent to Run
120, a continuous  sampling technique was used to collect backwash samples from
MM-2. The continuous sampling  technique consisted of placing  a siphon hose in
the backwash water discharge  and collecting  a sample throughout the duration of
the backwash cycle.

Grab  samples for asbestiform fiber  analysis were usually collected twice per week
from  the Lakewood Intake wetwell and also from the effluent of  each of the
pilot  filters. The 1 liter samples occupied approximately 2/3  of the volume  of the
sample bottles.  Most samples were collected in  triplicate, with a portion going to
Ontario Research Foundation  (ORF), to the School of Medicine  at the  University
of Minnesota at Duluth (UMD),  and to  NWQL at Duluth. Samples for ORF and
UMD were collected in 1  liter  plastic  containers and  samples  for  NWQL were
collected in 18.9 liter (5 gal)  plastic containers. The containers used  to  collect
samples  for asbestiform fiber analysis  were either  new or had  been specially
                                     27

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cleaned prior to use. In addition,  each container  was thoroughly rinsed  three
times with sample before sample collection.

CONVENTIONAL WATER QUALITY ANALYSES

Except for temperature, which was taken at the  time of sample  collection,
analyses of the 1 liter samples collected during each shift were made daily. Color
tests were  conducted using Nessler tube color standards prepared according to the
13th Edition of Standard Methods.1

The pH of each  sample was determined using a Beckman Model H-2  pH meter.
Odor tests were  subjective and results  were recorded only as odor or no odor.
Alkalinity, hardness, aluminum, and iron  were determined  using  premeasured
reagents obtained from Hach Chemical Corporation,  Ames, Iowa.  Bacteriological
tests were  made  according to the 13th Edition of Standard Methods1, using the
membrane  filter  technique, and included total coliform, fecal  coliform, and  fecal
streptococci tests. The suspended solids analyses made  on the backwash samples
and the dissolved oxygen tests were also conducted  as  set forth in the 13th Edi-
tion of Standard  Methods.1 Results of these tests are provided  in Appendices A-3,
A-4, and A-5.

TURBIDITY ANALYSES

Turbidity  measurements  were  made  with  three different  lurbidimeters, a  Hach
Model  2100A Laboratory Turbidimeter, a Hach Model  1720 Low Range  In-Line
Turbidimeter,  and a Monitek  Model 215/130  In-Line Turbidimeter.  The  Hach
2100A  unit was  used during  the entire study period,  but the two in-line  units
were used only during the last 6 l/2 weeks of the study. The two types  of turbidi-
meters were studied in order to learn  whether 15°  forward  scatter or 90° side
scatter  turbidimeters would  be  more effective in  detecting  fiber or turbidity
breakthrough.  No significant difference was observed.

The Hach 2100 A utilizes a nephelometric principle of operation. Light is passed
up  through the sample and light striking any suspended matter in  the sample  is
scattered at right angles to the light path. The  scattered light is received  by a
photomultiplier tube which converts  the light  energy into  an  electrical signal for
readout on a meter.  Standardization  of the instrument is accomplished with a set
of permanent turbidity standards which simulated Formazin solutions.

The Hach  low range turbidimeter   also  utilizes a nephelometric principle  of
operation  but  is a continuous flow unit requiring a sample flow rate of  from % to
                                     28

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Vi gpm.  Light passes  through the  sample and is scattered at right  angles and
received by two photoconductive cells which convert the light energy into an elec-
trical signal for readout on  a meter. Standardization can  be performed  with a
standard reflectance rod equivalent to 5.0 turbidity units (TU), but  during the
pilot filtration study, the unit was standardized using the Hach 2100A unit.

The  Monitek Model 215/130 turbidimeter utilizes a combination of forward light
scattering and dual-beam ratio computation. The unit consists of two sub-systems,
the  Model  215  transmitter  and the  Model  130  converter.  The  transmitter
measures the turbidity of the liquid flowing through it by projecting a  thin ribbon
of light through  the  flowing stream.  A direct beam detector  measures the
intensity of the source  light on the far side of the  sight glass and the scattered
light from particles in the flow is  measured by  a  scattered beam detector. The
scattered  beam detector measures  only light scattered in the  15° forward  di-
rection. Signals from the transmitter are received  by the Model 130 converter for
amplification  and indication. Standardization of the  unit was accomplished using
a Formazin solution.

ASBESTIFORM FIBER ANALYSES
Asbestos is a non-mineralogical term for asbestiform mineral  material which can
be used commercially.  Most of the world's asbestiform minerals are either chryso-
tile,  a fibrous serpentine, or  members of the amphibole  group of silicate minerals.
Chrysotile is  a hydrous magnesium  silicate.2 Electron  micrographs of chrysotile
indicate that  the fibrils are in the form  of a hollow tube and chrysotile fibers,
therefore,  have an  extremely large surface  area. The  chemical composition  of
chrysotile is hydrous magnesium silicate with trace quantities of iron and calcium.
One of the most important properties of chrysotile is its positive surface electrical
charge, compared  to  the  negative  surface  electrical  charge  of  fibrils in  the
amphibole group and  almost all  of the  commonly used filter media such as sand,
diatomite, and cellulose.  This may account, in part,  for the difficulty in  the
removal of chrysotile  fibers as  compared  to amphibole fibers.

The  amphibole  group  consists of crocidolite, anthophyllite,  and  tremolite.
Amphibole  fibers contain  primarily iron, magnesium, calcium, and sodium and are
solid and larger in  diameter than chrysotile, but with a much smaller surface area
on a per mass basis. A physical  comparison of amphibole and chrysotile fibers is
presented  in  Table 6. Several analytical  techniques  have been developed  for
analysis of asbestiform fiber content in water.  In  order to  provide the  most
definitive quantitative  and qualitative data  on fiber removal in the  pilot water
                                     29

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 treatment units, all available techniques were investigated prior to operation as to
 their effectiveness. An attempt was made to balance the accuracy of each method
 against the cost and time involved prior to making the final selection.
 TABLE 6.     COMPARATIVE PHYSICAL PROPERTIES OF AMPHIBOLE
 	CHRYSOTILE FIBERS IN LAKE SUPERIOR WATER
                                                  Diameter
   Fiber	^m	      in x id15"
 Amphibole                       0.084-3.377                     3.36-135.08
 Chrysotile	0.054-0.168	1.92-  5.96


 Transmission Electron Microscopy

 The transmission  electron  microscope combined  with electron  diffraction  has
 proven  quite  effective  in  the analysis of  asbestiform fibers  in  water samples.
 Electron diffraction patterns  from fibers of chrysotile have been measured with
 diameters in the range of 0.02 Mm to 0.025 Mm and lengths in the range of 0.10
 Mm to 0.15 Mm. With electron diffraction, a specific identification  of the minerals
 present  can be made using wavelength dispersive X-ray spectrometers. Two general
 methods of specimen  preparation technique  are  utilized but  in  both cases  the
 fibers are specifically identified by electron diffraction patterns as they are being
 counted. Results from  this technique are reported  in number of fibers per volume
 of sample analyzed  for both fiber groups.

 The Ontario Research Foundation (ORF) in Sheridan Park, Mississaugu, Ontario,
 Canada  utilized the transmission  electron microscopy process and reported results
 as the number of f/1 for both the serpentine (chrysotile) and  amphibole groups.
 Results  given as fiber counts and  separated  into amphibole  and chrysotile counts
 will refer to data from ORF. This laboratory has been employed by the EPA on a
 contract basis for related western  Lake Superior studies.

 The ORF procedure involved collecting solid material from the  water sample on a
 0.1   Mm pore size  membrane filter by filtering approximately 200 ml  of sample.
The membrane filter was then ashed in  a clean glass vial at a temperature of 70 °C
using a  plasma microincineration technique.  While  no  decomposition of  the
mineral  fibers occurs,  organic materials in  the  water and  the  filter  itself  are
oxidized to  carbon  dioxide.  The resultant  residue was  then  redispersed ultra-
sonically in filtered  distilled water and  centrifuged  onto a 1  cm diameter glass

                                     30

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cover disc. The disc was dried and a carbon coating applied by evaporation that
was scored and floated off onto  water, carrying the fibers with it. Pieces of this
material were then picked  up on  200 mesh copper grids. A maximum of 10 grid
squares were searched for asbestos fibers at a magnification of about 25,000 using
a JEOL Model No. JEM 100U transmission electron microscope. The fibers were
identified by  electron diffraction and measured for both  length and width. The
fiber  counts were  processed by a computer program which calculated and plotted
the  fiber  number and  mass  concentrations.   The  process was  sensitive  to  a
concentraton of 2  x 104 f/1 in water, below which the data were reported as below
detectable limits (BDL).3

Results of all ORF analyses are presented in Appendix E.

X-Ray Diffraction

The X-ray diffraction analysis  process is also specific to the mineral type present
and  will provide identification  by fiber group.  It  will  not  distinguish, however,
between  massive  forms of  the minerals  and  their fibrous  counterparts.   The
detection limit of  X-ray diffraction is generally not as slow as that  of transmission
electron  microscopy.  It does  provide,  however, a  more rapid and inexpensive
determination of  amphibole  mass concentration in water which  compares  well
with average electron microscope fiber counts for the same samples.

The EPA National Water Quality Laboratory (NWQL) in Duluth utilized the X-ray
diffraction technique and reported  the  concentration  of suspended  solids and
amphibole  mass in the water  samples. Results from this technique were reported in
mg/1 of suspended  solids and amphibole mass concentration. Results which  refer
to amphibole mass will refer to data from NWQL.  The NWQL has had consider-
able experience in the analysis of water for asbestiform fibers through  sampling
provided for  related  studies involving many raw water  and potable water intake
sources in the western Lake Superior area. The results they reported could be
readily compared with data from  other sources they evaluated  as well as provide  a
determination of the effectiveness of the  various removal processes  tested in the
pilot plant  operation. In  addition, unavoidable sample storage time due to ship-
ment  delays  prior to analysis could be  held  to  a  minimum  to preclude any
potential problems associated with long-term sample containment.

The NWQL  procedure involved pressure filtering, at approximately 50 psi, of 25
to 40 liter samples through  a  preweighed  Millipore 0.45 pm membrane filter. The
filter was dried  in  an oven at  70 ° C and the total suspended solids in mg/1 deter-
                                     31

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mined by the difference. A weighing correction factor was applied to compensate
for a small filter weight loss due to  leaching. The dry membrane filter with the
sample  was  then fastened to  a glass slide  using  a thin film  of lacquer  and
examined  with  a Philips  Model  No. APD-3500  vertical  X-ray  diffractometer
system. Amphibole mass analysis was generally  sensitive to 0.005 mg/1, with the
exact detection  limit dependent upon  the  individual sample.  When results were
reported as "less than",  the lower  detection  limit of the technique had been
reached. Work  by Cook'* indicates a  standard  deviation of ±3  per cent for
determining amphibole  concentrations in  typical  samples  with 0.1-0.3 mg/1
amphibole. For  samples having lower amphibole concentrations (< 0.1 mg/1) and
suspended solids ( >1.0 mg/1), this precision is reduced to ±25 per  cent. ^

Results of all NWQL analyses are presented in Appendix F.

Laboratory Selection

The  two laboratories  utilized  for  asbestiform  fiber analyses,  ORF and NWQL,
were  selected by EPA for use  in the pilot plant  study as  representative of a
number of qualified laboratories.  One additional facility, the University of Min-
nesota at Duluth, was utilized  for fiber analysis. Data from this facility are pre-
sented in Appendix G.
                                     32

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                                SECTION VI

                                  RESULTS

SEASONAL CONDITIONS
Raw water  quality parameters such as pH, alkalinity, hardness,  aluminum, and
iron are affected very  little by ambient conditions. Parameters which are affected
by  ambient  and  seasonal  conditions  include turbidity,  water temperature,
suspended solids, amphibole concentration,  and bacteriological counts. Changes in
climatologically related raw water quality parameters  generally follow  the climato-
logical events by 1 to  2 days. This relationship is evidenced by the relatively high
raw water turbidities of 5.6 TU and 6.3 TU which occurred on June  7, 1974 and
June  10, 1974,  respectively. These high turbidities were each preceded by a day
on  which rainfall in  excess of 1 in,  and wind  velocities of  10  miles per hour
(mph) or  higher were  recorded.  Other related data are presented in   Appen-
dices A-3, A-4 and A-5.

Work by Cook^'5 shows that the suspended solids concentration of the raw water
may be increased following heavy rainfall  or extended  periods of high winds from
the east or northeast.  If the suspended solids increase  is caused by heavy rainfall,
generally no  increase in amphibole concentration occurs. Rainfall does not cause
an  increase  in  amphibole concentrations  because the  suspended solids increase  is
the result of river runoff which  contains very little amphibole mass.  However, a
suspended solids concentration increase caused by high  wind usually results in a
corresponding increase in  amphibole concentration. Most  of the  amphibole mass
contained in the raw water comes  from a taconite tailings discharge at Silver Bay,
Minnesota. The prevailing water  circulation in western Lake Superior is counter-
clockwise, which results in the amphibole  fibers contained in the tailings from
Silver  Bay being transported to the Lakewood  Intake. Winds from the northeast
and  east  promote  this  counterclockwise circulation,  and  during  periods  of
sustained  east-northeasterly winds, water  with increased amphibole concentration
is transported  to the  Lakewood  Intake. High winds may  also  cause the resus-
pension of amphibole-rich sediment in the vicinity of  the intake.  Ice  cover, which
begins in  January and remains until late February or  March, prevents  wind-
generated resuspension of lake sediment.

According to Cook,^  amphibole concentrations in  raw water  from the  Lake-
wood  Intake  decrease  during  the  summer  until  fall  overturn occurs. Peak
amphibole concentrations occur in  spring  and in late fall.
                                      33

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This trend is also evident in the amphibole data obtained by the X-ray diffraction
technique  during the  pilot  filtration  study. Maximum  raw  water amphibole
concentrations  occurred  from April  19  to July 19, 1974 and ranged from 0.07 to
0.26 mg/1, with an average concentration of 0.15 mg/1. From July 19, 1974 to the
conclusion of the pilot filter study, the raw water amphibole concentration ranged
from 0.02 mg/1 to 0.10 mg/1, with an average concentration of 0.067 mg/1.

During  the  summer months,  changes in  raw  water temperature are often wind-
related. Offshore winds  cause upwelling which brings colder water  to the intake
and  easterly or  northeasterly winds  can  push  warm surface water  into the
Lakewood  Intake area,  causing  higher  water  temperatures.  This phenomenon  is
evidenced by the dramatic increase in raw water temperature which occurred on
July 9,  1974. The water temperature increased from 40 °F to55°F during a period
of sustained high winds  from the east.

GRANULAR MEDIA FILTRATION

Asbestiform Fiber Removal

For purposes of comparison and evaluation, experimental filter runs conducted on
the pilot units have been placed  in categories that  employed  similar  treatment
configurations.  The design and operational differences of the several pilot  units
have been  described previously  as have the  physical  modifications of  the  units,
made to vary  the treatment parameters. A  summary of the  results from  each
category of operation for the granular media  filters is  presented in Tables 7 and
8. The  tables present results  for  asbestiform  fiber removal summarized for each
category in  terms  of a selected fiber removal  goal. The successful goal chosen for
either amphibole or chrysotile fiber removal is below  detectable limits  (BDL), or
 40,000 fibers  per liter,  and  for  amphibole  mass removal less  than 0.005 mg/1.
Details of each individual granular media run  are provided in Appendices C-l and
C-2.

Turbidity Removal

It is difficult to made  definitive  statements  concerning the effect  of raw  water
turbidity on the  effluent turbidity from the pilot  filter units, because  of the
narrow  range of raw water turbidities which  occurred during the pilot  filtration
study.  In the range of raw water turbidities which occurred, the effluent turbidity
was affected more by type and  amount of chemicals added than by the turbidity
of the raw water, particularly with the granular media filters.
                                     34

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         TABLE 7.
GRANULAR MEDIA FILTRATION (MM-1) SUMMARY OF ASBESTIFORM FIBER REMOVAL BY CATEGORY
	 Categories 	
Alum & Anionic Polymer


Filtration w/o





MM-1-
Dual
Media





Sedimentation
4 gpm/sq.ft.
(Runs 1-40)

- (Separan NP-10 or 847A)
(Runs 1,2,20-24)



Alum & Nonionic Polymer
- (N-17 or 98SN)
(Runs 4-19, 25-40)



Alum & Nonionic


Sedimentation
Tube Settlers

4gpm/sq.ft.
(Runs 41 -87)


i— Polymer (98SN)
(Runs 41-44, 64-86)
Alum & Nonionic Polymer
(985N) and Coagulant

Aid (Bentonite)
(Run 87)
FeCl3 & Nonionic
1— Polymer (985N)
(Runs 45-63)
NWQL Amphibole
Mass Results
Samples
Analyzed
with Detection Samples with
Limit <0.005 mg/1 filtrate £0.005 mg/1
0





3





12


1



2


0





2





12


1



1


ORF Amphibole
Fiber Count Results
Samples with
Samples <0.04x!06
Analyzed f/1
0





7





13


1



2


0





6





13


0



2


ORF Chrysotile
Fiber Count Results
Samples with
Samples 
-------
TABLE 8. GRANULAR MEDIA FILTRATION (MM-2) SUMMARY OF ASBESTIFORM FIBER REMOVAL BY CATEGORY
. Categories
Alum & Nonionic
Polymer (985N)


Cloquet





Dual
»*- ji_

(Runs 1-76)



(Runs 75,76)


2 gpm/sq.ft.
(Run 76)


Alum & Nonionic
Polymer(985N)
4 gpm/sq.ft.
(Run 75)
Alum & Nonionic
Polymer (985N)



Lake wood
(Runs 1-74)












2 gpm/sq.ft.
(Runs 54-56)
FeCls & Cationic
Polymer (C-31)
4 gpm/sq.ft.
(Runs 1-13,16)
FeC13 & Nonionic
_ Polymer (N-17)
4 gpm/sq.ft.
(Runs 19-23)
Alum & Nonionic
Polymer
— (N-17 & 985N)
4 gpm/sq.ft.
(Runs 24-53)
Alum & Nonionic
Polymer (985N)
6-8 gpm/sq.ft.
(Runs 57-74)
NWQL Amphibole
Mass Results
Samples
Analyzed
with Detection Samples with
Limit £0.005 me/1 filtrate £0.00 5 mg/1
1





0



2



0



0



2




0



1





0



2



0



0



2




0



ORF Amphibole
Fiber Count Results
Samples with
Samples * 0.04x106
Analyzed f/1
1





0



2



2



0



3




3



1





0



1



2



0



3




2



ORF Chrysolite
Fiber Count Results
Samples with
Samples *0.04xlo6
Analyzed f/1
1





0



2



2



0



3




3



o









0



1



0



0




0




-------
   TABLE 8.
(CONTINUED)
Categories
Chem. Add. Alum & Nonionic Polymer
/~*ln<-...A* +~ 4...~. 171 — t, Jt «._« /~n f* SnocKT\








Tri.
Media
(Runs
77—140


uri
^4



	 *^»w*fi*w» 	 i\j iwu i loan — — — -T gfjui/ 314.1 1. \_7oji^y
(Run 106) Mixers (Run 106)
Chem. Add. Alum & Nonionic Polymer
















— Lakewood —
(Runs 77-105,
107-137)









-to Mixing — — 4 gpm/sq.ft. (985N)
Chamber (Runs 77-81, 84-92)
Alum & Nonionic Polymer
4 gpm/sq.ft. (985N)









Chem. Add.
-to two Flash
Mixers


(Runs 93-105,
107-113,115,140a)
Alum & Nonionic Polymer
— 2 gpm/sq.ft. (98 5N)
(Run 114)

Alum&Anionic&Cationic Poly.
— (A-23&Catfloc B or C-31)
4 gpm/sq.ft. (Run 116,118,139)
Alum & Cationic Polymer
— 4 gpm/sq.ft. (Catfloc B)
(Run 117)
Alum & Anionie & Nonionic
Polymers (A-23 & 985N)
4 gpm/sq.ft.
(Runs 119,120,138)
Alum & Nonionic Polymer








Mixers





1 — 4 gpm/sq.ft. (98 5N)
(Runs 121,122,123)
Alum & Nonionic & Anionie
— Polymers (985N & A-23)
4 gpm/sq.ft. (Runs 124,127,128)
Alum & Anionie & Cationic
Pr»l vtn»»re ( A 0 "\ XT C* "31^
• r oiyrners \z\ — i j QE> v^ — o i )
4 gpm/sq.ft. (Runs 125,126)
Alum & Nonionic Polymer
— 6 gpm/sq.ft. (985N)
(Runs 129-133)
Alum & Cationic Polymer
1 	 4 gpm/sq.ft. (C-31)
(Runs 134-137)
NWQL Amphibole
Mass Results
Samples
Analyzed
with Detection Samples with
Limit SO. 00 5 mg/1 filtrate iO.OO 5 mg/1
1


1


5



1



2


0


2



1


2


1


2


1


1


1


5



1



2


0


2



1


2


1


2


1


ORF Amphibole
Fiber Count Results
Samples with
Samples <0.04xl06
Analyzed f/1
1


1


5



1



2


0


2



1


2


1


2


1


1


1


5



1



2


0


2



1


2


1


2


1


ORF Chrysotile
Fiber Count Results
Samples with
Samples S0.04xl06
Analyzed f/1
1


1


5



1



2


0


2



1


2


1


2


1


1


0


2



0



0


0


0



1


0


1


0


0


Sedimentation Tube Settlers (Run 140)

-------
 A plot  of raw water turbidity and  effluent turbidity versus time  for Run 31 on
 MM-1 is presented on Figure 6. Although the raw water turbidity  increased from
 0.8 TU  to 4.6 TU  during  the run,  the effluent turbidity  changed only slightly,
 increasing from about  0.07 TU to 0.16 TU. No changes in chemical feeds or flow
 rate were  made  at  the time  of the turbidity  increase.  A  similar plot of the
 subsequent run  on  the  MM-1  unit  on Figure 7  indicates that  although the  raw
 water turbidity  varied  from  1.4  to 5.6 TU, the effluent  turbidity only ranged
 from 0.07  to 0.27 TU and the low and high effluent turbidities did not follow the
 low and high raw water turbidities. The chemical dosages on this run were slightly
 lower than those of  Run 31 and turbidity breakthrough was beginning to occur at
 the conclusion of Run 32.

 The effect  of raw water turbidity on filter run lengths of the granular filters was
 twofold.  First was the  direct effect: the higher solids loading associated with a
 higher turbidity  resulted in a more  rapid rate of head loss buildup. Second  was
 the indirect effect: higher turbidities  required higher chemical dosages to maintain
 satisfactory effluent  turbidity  and  these higher chemical  dosages resulted in  a
 more rapid rate  of  head  loss buildup. For  the range of  raw water  turbidities
 experienced during the pilot filtration study, the effect of the  increased chemical
 dosages was much greater than the effect of the increased solids loading associated
 with a higher turbidity.

 Operational Variations

 Where possible, analysis  of the effects  of the various treatment  configurations
 included all of one or more of the major categories listed in Tables  7 and 8. How-
 ever, in many instances, a further  breakdown  of a major category into  subsets or
 series of runs within that category was necessary. In  this manner,  a base line of
 treatment  could  be  established in which all  treatment variables would  be held
 constant except for those being compared.

 Runs conducted on  the  MM-2 unit during the  period of high turbidity were made
 at flow rates of 116 m3/m2 day (2 gpm/ft2) and 350 m3/m2 day (6 gpm/ft2) and
results were similar to those obtained on the MM-1 unit. Seventy-three runs with
sufficient chemical dosages had satisfactory effluent turbidities  regardless of raw
water turbidity  (within the range of raw water turbidities experienced during  the
pilot  filtration  study), and  those without sufficient chemical  addition  had high
effluent turbidities even when the raw water turbidity was less than  1.0 TU.

Table 9  shows  the  number of runs made  on granular filters  at  filter rates of
4 gpm/ft2 or higher.  All of the MM-1 runs were made at 4 gpm/ft2 and this unit

                                      38

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  6.0

  5.0

  4.0


  3.0



  2.0
p:  os
 •  0.8

t  °7
5  0.6
CD
(T  0.5
   0.4
   0.3
   0.2
   O.I
   .09
   .08
   .07

   .06
       I
                   rv
                              *
                                        RAW WATER
                                        EFFLUENT
		1	1—I—I—I	1	1—I—I	1
      0  2  4  6  8  10  12 14 16  18  20 22 24 26  28  30 32 34
                            HOURS
      FIGURE  6 . RAW WATER AND EFFLUENT TURBIDITY
                 CURVES. UNIT MM-I RUN 31 .
                           39

-------
6.0

5.0

4.0


3.0



2.0
•=>  i.o
I-  0.9
>_" 0.8
t  0.7
5  0.6
CD
*  0.5
0.4
0.3
0.2
O.I
.09
.08
.07

.06
           I   1   I
                                   WATER
                      •-•	-*  EFFLUENT
                                     I
                             V
   0  2  4  6  8  10  12  14 16  18  20  22  24  26  28  30 32  34
                          HOURS

   FIGURE  7 . RAW WATER AND EFFLUENT TURBIDITY
               CURVES. UNIT MM-I  RUN 32
                         40

-------
                                                               •~\
was operated exclusively with dual media. Thirty-six runs at 5 gpm/ftz and higher
rates were made on the MM-2 filter unit. Of these, 23 were made with dual media
and 13 with tri-media.

TABLE 9.     NUMBER OF RUNS MADE AT  OR NEAR  INDICATED
              FILTER RATES
Pilot Unit
MM-1
MM-2
4 gpm/ft2
73
85
5 gpm/ft2
0
14
6 gpm/ft2
0
8
7 gpm/ft2
0
14
Chemical Additions
Either alum or FeClg  was used as a coagulant in all of the granular media unit
filter  runs. A comparison of their relative effectiveness in the  MM-1  unit can be
made by  examining the  data  from  two  major categories in  which a nonionic
polymer, 985N, was utilized. The data in App.G4show that, overall, the average
raw and filtered turbidities appear to be quite similar for  Runs 41-44 and 64-86
in which alum was used  and Runs 45-63 in which FeCl^ was used. The length of
those filter runs in which alum was used was longer, however; averaging 23 hours
as compared  to 13 hours in those runs using
A more direct  comparison of the two coagulants may be made between Runs
41-44, utilizing alum,  and Runs 45-49, utilizing FeC^. In these runs, the polymer
was introduced to the floe chamber of the MM-1 unit in both cases,- essentially
equating  the treatment  processes except  for the difference in coagulant.    The
data,  from Appendix  C-l, show that a  slight but significant increase in turbidity
removal was achieved  with alum as a coagulant when the average raw and effluent
turbidities of the  alum  runs, 0.97 TUand 0.09 TU, are compared to the average
raw and  effluent turbidities of the FeCl3  runs, 0.68 TU  and 0.13TU. In these
runs,  the  alum  dosage averaged  16.5mg/l and  the FeCl-^ dosage averaged
12.1 mg/1. Filter run lengths again were longer with the alum runs, averaging 22.3
hours compared to 16.8  hours with the FeQ3.  Sludge solids produced  and back-
wash  volume as a per cent of the  treated water were both higher in the FeCl-^
runs,  averaging  0.051 lb/1000  gal  and  2.42 per cent, as compared  to 0.018
lb/1000 gal and 1.88 per cent in the alum runs.

A similar  comparison  can be made between alum and  FeClo in the MM-2 unit by
examining Runs 24-53 in which alum was used and Runs 19-23 in which

                                     41

-------
was used. In both categories,  the coagulants were used with a nonionic polymer,
N-17  or 985N. As  shown  in App.O2 the overall results in the two  categories
demonstrated a slightly  better turbidity removal  with alum as the coagulant by
comparing  average  effluent turbidities  of 0.20 TU with  alum to 0.36  TU  with
FeCl^. Longer  filter runs were also achieved with alum as the coagulant in these
categories.  The data from Appendix C-2 show an average length  of 14.6 hours as
compared to 10.6 hours with
Comparing directly Runs 20, 22, and  23,  in which FeCl3 was used, with Runs
24-27  and 34-41, in which  alum was  used, the  data  from Appendix C-2 again
show that  slightly better turbidity removals were achieved in the alum runs. In
both  sets of runs, the  coagulant was introduced  to the mixing chamber of the
MM-2  unit  and the  polymer,  N-17  in both series, was introduced  to the first
flocculation chamber  of the unit. The average raw and effluent turbidities of the
FeC^  runs were  0.68 TU and  0.35 TU while  the  average  raw  and effluent
turbidities of the alum runs were 1.09 TU and 0.20 TU.  The lengths of filter runs
also were better with those runs using alum, averaging 15.1 hours as compared to
1 2. 1 hours in  the  FeCl^ runs. In these  runs, the FeCl^ dosage averaged 1 1 .4 mg/1
and the alum averaged 18.6 rng/1 while the dosage of N-17 averaged approximately
0.25 mg/1 in both sets of runs.

A  total of four different coagulant aids  or polymers were utilized  in  the MM-1
unit to improve the results of  the  use  of the  coagulants. The  polymers  were
intended primarily to extend filter runs and prevent breakthrough in the filter by
strengthening the chemical floe. Two  anionic polymers,  Separan NP-10 and 847 A,
and two nonionic polymers, N-17 and 985N, were  used.

Mixing accomplished by the external flash mixers and the in-line mixers was more
effective than  the  mixing provided by the pilot unit mixing system as evidenced
by better turbidity removals  and longer filter runs. That the external flash mixers
and in-line mixers consisted  of  more than  one stage is the probable reason for
increased effectiveness. The staged systems greatly  reduced  the possibility of short
circuiting  during the mixing process and,  therefore, improved  the overall  pilot
plant operation.

As  indicated in Table 10 certain filter  runs with  the in-line  mixers produced a
lower effluent  turbidity  than the two-stage  external mixers, but at a higher cost
and with  a  much  greater possibility  of turbidity  breakthrough. In addition, the
effluent turbidity of the runs conducted with the two-stage mixers  could probably
be lowered by a slight increase in  alum dosage.
                                     42

-------
Dual and Tri-Media Filter Beds
The filter bed in the MM-2  unit was utilized in both a dual and a tri-media con-
figuration to investigate the differences that the two filter beds would have on the
raw water at the Duluth Lakewood Pumping Station. The results obtained using
dual and tri-media filter beds are presented  in Table 10.  All runs selected for use
in calculating the values presented in the table met the following conditions:
1.  Filtration without sedimentation
2.  Filter rate of 214-277 m3/m2 day (3.4-4.4 gpm/ft2)
3.  Filtered water temperature of 37° F to 44° F
4.  Raw water turbidity of 0.46 to 0.95 TU
5.  Run length is equal to time required to reach 8 ft of water head loss or 0.20
TU in effluent
6.  Alum and 985N used for chemical treatment

TABLE 10.       RESULTS  OBTAINED USING DUAL AND TRI-MEDIA
                 FILTER BEDS
Media
Dual

Tri

Tri

Tri
Mixing No. of Avg. length
mode runs of runs,
hr
Alum @ rapid mix 5 19.4
Poly @ flocculator
Alum @ rapid mix 3 11.1
Poly @ flocculator
Two-stage 7 1 8.9
flash mix
In-line mixers 3 20.3
Avg. effl. Avg. chem.
turb., costs
TU S/1000 gal
0.12 0.0051

0.10 0.0044

0.10 0.0039

0.06 0.0042
Based  on data  presented in Table 10, the tri-media filter bed produced lower
effluent turbidities at lower  chemical costs than did the dual-media filter bed. The
lowest chemical cost was obtained using  two-stage flash mixing prior to  the tri-
media  filter bed and the lowest effluent turbidity was obtained using the Kenics
in-line mixers prior to filtration. However, problems with turbidity breakthrough
were encountered when using the  in-line mixers which did not occur when using
two-stage  flash mixing. An increase in alum dosage probably would have lowered
the effluent turbidity during those  runs with two-stage flash mixing.
                                     43

-------
 Filter runs conducted with Duluth raw water in the dual media bed configuration
 in MM-2 included three categories of filter rates. Runs 54-56 were conducted at
 116m3/m2 day  (2 gpm/ft2), Runs  42-53 at  232 m3/m2 day (4 gpm/ft2)  and
 Runs 57-74  at  348-464  m3/m2 day  (6-8  gpm/ft2).  For comparison purposes,
 those runs utilizing alum  and a nonionic polymer, 985N, introduced at the same
 point in the  treatment process were  analyzed. The data in Table 8, Appendix C-l,
 and  Appendix C-2 again  show that little difference resulted in the finished water
 quality, with  average  effluent qualities of  0.14 TU,  0.18 TU,  and  0.18 TU,
 respectively.  The rate of head loss  buildup  did  vary proportionately,  however,
 with  average  filter  run   lengths  of 41.8  hours,  18.1  hours and  10.3 hours,
 respectively.

 Two  comparisions  of  filtration  rates can  be  made  in  the  tri-media  filter bed
 configuration in the MM-2 unit involving alum and a  nonionic polymer, 985N.
 The  first, utilizing chemical addition to the two external flash mixers as shown in
 Table 8 shows a slightly better turbidity  removal  at 116 m3/m2 day (2 gpm/ft2),
                      ^   9               "*)
 as compared  to 232 m^/m^  day (4 gpm/ftz).  However, since only one  run was
                      ^
 involved at the 2 gpm/ftz rate, no definitive conclusions can be made.

 The  second comparison involves chemical addition through in-line mixers  at fil-
 tration rates of 232 m3/m2 day (4 gpm/ft2) and 348 m3/m2 day (6 gpm/ft2). As
 shown in Table  8,  turbidity  removals were approximately the same, with average
 effluent turbidities  of  0.06 TU and  0.10 TU,  respectively. As the filter runs at
      O   O              f\
 232  nrVmz day (4 gpm/ftz) were not carried to terminal conditions, no definitive
 comparisons of filter run lengths can  be made in these  two categories.

 Head Loss, Filter Run Length, and Terminal Turbidity

The  rate of head loss, the length of the filter run,  and the terminal turbidity
were factors used to evaluate the performance  of the  various  filter configurations
utilized  in  this study. Ideally, terminal head loss  at about 8 ft of water  and  the
beginning  of  turbidity  breakthrough would  occur  at  the  same time  with  a
resultant optimum filter run length.

 Figure 8 shows  the head  loss and effluent  turbidity curves  of Run 107 of the
MM-2 unit. These  curves show  that turbidity breakthrough  began  to  occur at
about the  28th  hour of the  filter run, a point where the head loss was about
4.5 ft of water, considerably below a  terminal head loss condition.

Figure 9,  the head  loss and  effluent turbidity curves of Run 109 of the MM-2
unit, shows terminal head loss and turbidity breakthrough occurring at about the
                                    44

-------
                         HEAD  LOSS  IN  FEET OF  WATER
     O
     c
     :o
     m


     09
3) CD I
c — m
z 5 >
  H O
  0 2
  c w
  3 0)
  <
  m >
  o> z
  •   o
     m
             ro
o>
  ro
     c
     x
     i
                   p
                   01
                        ro

                        b
ro
bi
OJ

6
                                                       t
                                     I
                              I
                                           ro
                                           O
                   ro    o»

                   TURBIDITY,TU
                                                ro
                                                      ro
                                                            ro
                      V

                      i

                      i  *
                      5  o
pi
b
                                                               a
                                                                           N


                                                                           P


                                                                           g

-------
  10.0
  9.0
  8.0
CC

£7.0
u_
O  6.0

I-
UJ
UJ
^  5.0
V)
V) 4.0
O
< 3.0
UJ
X
  2.0
   1.0
                       Average Raw Turbidity = 0.62 TU
                     HEAD  LOSS

                     TURBIDITY
      -cr
                                .36
                                .32
                                .28
                                .24
                                .20  «
                                   >-
                                   H

                                   O


                                   cr

                                   h-
                                .12
                                .08
                                .04
                           I
I
I
                    10    14     18     22

                              HOURS
            26     30    34    38
         FIGURE  9  .HEAD  LOSS  AND EFFLUENT  TURBIDITY

                       CURVES. UNIT MM-2  RUN 109.
                                  46

-------
same  time.  This  particular  run was conducted for 4 hours  before  the  run was
terminated,  with an average raw  turbidity of 0.62 TU  and an average effluent
turbidity of 0.10 TU.

The terminal head loss, in feet of water, terminal turbidity, in TU,  and the length
of filter run, in hours, are presented in Appendices C-l and C-2  for each filter run
of the granular  media units. These data reflect the progressively increasing filter
run lengths that  occurred with no sacrifice in effluent quality. This was due to
the optimum selection  of coagulants  and  polymers and their  dosage rates that
occurred  as  the study  progressed and  operating experience was gained. In
addition, utilization of certain unit processes that provided better chemical mixing
and flocculation, as well  as better filtration,  also produced  a marked increase in
filter  run  lengths as well as increased turbidity and asbestiform  fiber  removal. For
the most  part, the type and method of coagulant addition or the rate of filtration
had the  most effect on  the  rate  of  head loss  buildup and  filter run lengths.
Individual head loss and turbidity curves for each granular media run are provided
in Appendices D-l and D-2.

Backwash Solids

The relationship  of backwash  solids to sludge volume  is presented in  Table 11.
The values  presented are based on SS  tests and settleable solids tests performed
on  backwash water samples  collected during  the  pilot filtration study.  Sludge
production given in the table is in terms of sludge  produced per 1000 gallons of
water treated.

TABLE 11.      RELATIONSHIP  OF BACKWASH SOLIDS TO SLUDGE
                 VOLUME - UNIT MM-2
Run
132
133
134
137
138
139
Backwash
solids,
lb/1000 gala
0.060
0.061
0.046
0.055
0.038
0.043
SS
mg/1
166
L06
227
1-24
208
132
Cone, after
60 min,
%
0.72
0.62
0.38
0.44
1.09
1.47
Gal of
sludge
per 1000 gal
1.00
1.17
1.46
1.49
0.42
0.35

'Based on theoretical solids production
                                      47

-------
Backwash Water

In order to determine the asbestiform fiber concentration of the backwash water,
a sample  of the backwash water from the MM-2 unit,  Run  138, was allowed to
settle for approximately  10  days.  Supernatant  from the sample was withdrawn
and  submitted  for  analysis. The results  indicate a low concentration of asbesti-
form fibers in  the  supernatant  with 0.0152 x  10°  f/1  of amphibole and 0.57 x
10" f/l amphibole  and  1.3  x   10"  f/1  chrysotile  as reported  by this same
laboratory.  This  would  indicate that supernatant  from settled backwash  water
could be recycled for treatment after a sufficient period  allowed for settling.

Filtration With  and  Without Sedimentation

The  MM-1 unit was operated  in two configurations, filtration without sedimenta-
tion  in Runs 1-40  and filtration preceded by  sedimentation in tube settlers in
Runs 41-87.  The purpose of this dual operation was to investigate the effects of-
sedimentation on effluent turbidity, filter breakthrough,  and filter run lengths.

A comparison of the relative  effects of the two  configurations may be made with
the  results of two series of filter runs: Runs 2540 which were conducted without
sedimentation, and Runs 77-86 which were conducted with sedimentation prior to
filtration.  Runs 77-86  were  selected  for  comparison  as a measurement  of the
solids retained  in the sedimentation basin  which was made independently  of the
solids backwashed from the  filter bed. In both series of runs, alum  was used as
the   coagulant at approximately  25 mg/1  and  985N as the polymer at approx-
imately 0.05 mg/1. Turbidity  removal was slightly better with sedimentation than
without sedimentation. Average  raw and effluent turbidities for Runs 25-40 were
1.65  TU  and 0.13TU  while  the average  raw  and effluent  turbidities for Runs
77-86 were 0.79 TU and 0.09  TU.

In addition,  the data from Appendix C-l indicate  that the average run lengths
without sedimentation were  considerably shorter than  those with sedimentation,
17.8 hours as compared to 25.1 hours. An examination of the backwash solids for
those runs with sedimentation revealed  that the solids loading on  the filter was
reduced by approximately 27 per  cent  by the sedimentation step.  It would be
expected  that the filter run length would be  increased 37  per cent by the re-
duction in solids loading. In actuality, the run length increased 41 per cent.
                                      48

-------
 This  observation is reinforced  by examining  the  data in Appendix C-2 for  Run
 115 and  Run  140 on  the  MM-2 unit. Both  of these runs  were conducted with
 alum as the coagulant  at approximately  14.5 mg/1 and  985N  as the polymer at
 approximately  0.045 mg/1.  Run  115 was  conducted  without sedimentation  and
 Run  140 was conducted with sedimentation prior  to filtration.  Again, the average
 raw and effluent turbidities were about the same, 0.77 TU  and 0.09 TU for  Run
 115,  and 0.47 TU and 0.06 TU for Run 140. The run length, however, was longer
 with  Run 140  which  included  sedimentation, 33.6 hours  as compared to 24.8
 hours with  Run 115. Analysis  of backwash solids  samples from Run 140 showed
 that the majority  of the total  solids removed  were removed from  the filter bed,
 70 per cent, as compared to  30 per cent from the sedimentation  basin.

 DIATOMACEOUS EARTH FILTRATION

 Asbestiform Fiber Removal

 Two  major types of DE media units were  used  in  the pilot plant study.  The
 design and  operational differences of the two units have been described  pre-
 viously.  An examination of the results  of  the  various processes  utilized is
 presented in this section and is  summarized below.

 The DE unit designated as BIF was used exclusively  to  provide data on vacuum
 filtration. One other vacuum DE unit was available, but was held in reserve. Data
 from  vacuum DE filtration  runs will be  referred to  as BIF  data. Two DE units,
 designated as ERD-1  and  ERD-2,  were  used  exclusively  to  provide  data on
 pressure  filtration. Since the physical configuration of these two units was identi-
 cal, data  gathered from filter runs on these  two  pressure  units have been com-
 bined and will be referred to as ERD data.

 The data listed in Tables 12 and 13 summarize  the results  of the BIF and ERD
 runs and are used to  compare sets of runs with similar treatment configurations.
 Details of each individual DE run are provided  in Appendices C-3 and C-4.

 Filter runs with the  BIF unit and especially with the ERD  units were quite long
 when conducted to their respective maximum  head loss differentials. Under good
 quality effluent  production  conditions (effluent turbidity 0.2 TU or less), filter
run lengths  of 30  to 40 hours  could be achieved easily with the BIF unit. Under
 similar conditions, the ERD unit could easily produce filter runs of over 60 to 70
hours duration. Once  a  maximum filter run length for a particular test condition
had been established,  filter  runs were limited  to a maximum of 24  hours to
                                     49

-------
en
O
TABLE 12. VACUUM DIATOMACEOUS EARTH FILTRATION SUMMARY OF ASBESTIFORM FIBER REMOVAL BY CATEGORY
Categories
One
Step
Precoat






BIF-













Igpm/sqft
(Runs
1T-14T
-Precoat & Body Feed only (Runs 1T-5T,6,7)
-Anionic Polymer (A-23) to Precoat (Runs 8T-14T.8)
-Nonionic Polymer (985N) to Precoat (Runs 1-5)

-Cationic Polymer (C-31 or S73C) to Precoat (Runs 9-17)
1-17)




Medium
Coarse








Two
Step
L Precoat —
Igpm/sqft
(Runs
18-122)






Step of
Precoat




p Cationic Polymer (S73C) to
Total Precoat (Runs 18-24,26,29-35)
— Anionic Polymer (A— 23) to
Total Precoat (Runs 36-41)
-Alum to 2nd Step of
Precoat (Runs 42,46,47,49-51)

— Alum & Soda Ash to 2nd
Step of Precoat (Runs 60,61)

- Alum & Soda Ash to 2nd Step
of Precoat and to Body Feed
(Runs 62)
— Anionic Polymer (A-23) to 2nd
Step of Precoat, Alum & Soda
Ash to Body Feed (Runs 63-66,69-74)








Very
Coarse
LDE in 1st —
Step of
Precoat






p Cationic Polymer (573C) to
Total Precoat (Runs 25,28)
—Alum to 2nd Step of
Precoat (Runs 52-57)

- Alum & Soda Ash to 2nd Step
of Precoat (Runs 58,59,89-103)
-Anionic Polymer (A— 23) to 2nd Step
of Precoat, Alum & Soda Ash to
Body Feed (Runs 75-78,111, 112)

— Anionic Polymer (A— 23) to 2nd
Step of Precoat (Runs 79, 80)
- Cationic Polymer (Catfloc B) to
Raw Water (Runs 82-84, 86-88)
- Alum & Soda Ash to 2nd Step of
Precoat and to Body Feed
(Runs 104-109,120-122)
—Alum & Soda Ash to 2nd Step of
Precoat, Cationic Polymer (Catfloc B)
to Raw Water (Runs 110,113-119)
Mass Results
Samples
Analyzed Samples with
with Detection SO. 00 5 mg/1
Limit sn.nnfi mg/l Amnh. mass
0
2
0

0
3

0

1


0

0


3


0

0


2

2



1

1

2


4


0
1
0

0
2

0

1


0

0


2


0

o


2

2



0

1

2


4


ORF Amphibole Fiber
Count Results
Samples with
Samples <0.04xl06
Analyzed f/1
0
3
0

' 1
4

1

2


0

0


3


1

o


2

2



1

3

3


4


0
2
0

0
1

1

o


0

o


3


0

o


o

2



1

3

2


4


ORF Chrysotile Fiber
Count Results
Samples with
Samples <0.04xlfl6
Analyzed f/1
0
3
0

1
4

0

2


0

o


3


1

0


2

2



1

3

3


4


0
1
o

0
o

1




0

o


1


0

0


0

0



1

o

o


o



-------
TABLE 13. PRESSURE DIATOMACEOUS EARTH FILTRATION SUMMARY OF ASBESTIFORM FIBER REMOVAL BY CATEGORY
Categories

One


ERD 1&2 —




Step
Precoat
Igpm/sq.ft.
(Runs 1A-6A,
1-27)





Two
Step
Precoat
Igpm/sq.ft.
(Runs 2 8-86)

Precoat & Body Feed only
(Runs 2,7-11)
Cationic Polymer to Precoat
	 (C— 31 or 573C)
(Runs 1A-6A, 12-15,20)
Alum to Precoat
(Runs 21-27)
Anionic Polymer to Precoat
1 	 (A-23) (Run 3)
Anionic I'olymer (A-23) to 2nd Step
	 of Precoat, Alum & Soda Ash to
Body Feed (Run 72)
Alum to 2nd Step of Precoat (Runs 28-37)
Alum & Soda Ash 10 2nd Step of Precoat
(Runs 38-44, 54-60, 62-66)
Cationic Polymer to Raw Water
(Catfloc B) (Runs 45-51;
Alum & Soda Ash to 2nd Step of Precoat
and to Body Feed
(Runs 67-71,82,85,86)
Alum & Soda Ash to 2nd Step of Precoat,
Cationic Polymer (Catfloc B) to Raw Water
(Runs 73-76, 78-81)
NWQL Amphibole Mass
Results
Samples
Analyzed Samples with
with Detection < 0.005 mg/1
Limit SO. 005 mg/1 Amphibole mass
1
5
0
0
1
1
6
5
3
3
1
5
0
0
1
1
6
5
3
3
ORF Amphibole Fiber
Count Results
Samples with
Samples = 0.04x106
Analyzed f/1
1
6
1
0
1
2
6
5
3
3
0
3
1
0
1
0
3
5
3
3
ORF Chrysotile Fiber
Count Results
Samples with
Samples S0.04xlfl6
Analyzed f/1
1
6
1
0
1
2
6
5
3
3
0
1
0
0
0
0
1
2
0
0

-------
permit  variations of  treatment  within  the  test  condition. Because of  this,
comparisons of filter run lengths cannot always be made and quality of effluent
and asbestiform fiber removal must be relied upon for judgment criteria.

Turbidity Removal

High raw water turbidities occurred from  June 6 to June  15. No other extended
periods of raw water turbidities over  1.5 TU  were experienced  during the  pilot
filtration  study and  fluctuations in raw water turbidities  in the range of 0.8 to
1.5 TU did not appear  to  affect effluent turbidities. A plot of raw water  and
effluent  turbidities  versus  time for  Run  47  on the  ERD-2  unit is given on
Figure 10.  Raw water turbidities during this run varied from 0.84 to 1.3 TU and
effluent turbidities varied from 0.08 to 0.18TU. However,  fluctuations in effluent
turbidity did not follow  the increases and decreases of the raw water turbidity.

As with the pressure DE unit, all  runs conducted on the BIF  unit during the
period of high turbidities, which began on June 6, 1974,  had very  high effluent
turbidities. A plot of raw water and effluent turbidities for Run 25 on the  BIF
unit is given on Figure 11.

A review of the data for BIF in  Appendix C-3  shows that, on runs where the
average raw water turbidity was greater than 1.5TU, the  lowest average effluent
turbidity  attained  was  0.3 TU.  This  inability to attain low effluent  turbidities
would seem to be the result of high raw water turbidity.

Two head loss and effluent  turbidity  curves are presented on Figures 12 and  13.
Figure 12 representing Run 110 of the BIF  unit, demonstrates the steady, almost
straightline head  loss buildup and rather constant effluent turbidity characterized
by vacuum DE units. Figure  13, representing Run 79 of the ERD-2 unit, demon-
strates a  typical  head loss curve with  a gradually diminishing  rate of head loss
buildup. This type of head loss curve  is due to the cylindrical shape of the filter
septa in which the filter surface increases as  the filter cake  increases, thus negating
somewhat the head loss  buildup in  the  filter cake.

Figures 14 and  15 are included to demonstrate the effect of the  two-step precoat
process on the  initial effluent turbidity. On Figure 14, a single-step precoat  pro-
cedure was used with a subsequently high initial effluent turbidity. Approximately
4 hours were required  to attain the  necessary filter permeability  to  produce  a
steady effluent  turbidity. On Figure 15, however, a two step precoat application
produced  an  almost  immediate steady state level  in the effluent turbidity. With
                                      52

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  6.0

  5.0

  4.0


  3.0



  2.0
  1.0
  0.9
  0.8
  0.7
  0.6
g05
CD
tr. 0.4
  0.3
  0.2
  O.I
  .09
  .08
  .0 7
  .06
                   RAW WATER
            •-	• EFFLUENT
v\
    0  2  4  6  8  10 12 14  16  18 20 22 24 26 28 30 32 34
                         HOURS

    FIGURE  10 . RAW WATER AND EFFLUENT TURBIDITY
               CURVES. UNIT ERD-2 RUN 47.
                         53

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  6.0

  5.0

  4.0

  3.0


  2.0
(- 9.0
>T8.0
±7.0
m
  5.0
  4:0
  3.0
  2.0
  0. I
  .09
  .08
  .07
  .06
        RAW WATER
  	•• EFFLUENT
i   i   i   i
               i  i   i
     0  2   4  6   8  10 12  14  16  18  20 22 24 26 28 30 32  34
                            HOURS
     FIGURE II .  RAW WATER AND EFFLUENT  TURBIDITY
                 CURVES.  UNIT BIF RUN 25.
                           54

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                                        HEAD  LOSS  IN  FEET  OF WATER
                                    IV)
                                                     Ol
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                                           TURBIDITY   TU

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  30
  25
UI2O
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a
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                      Av»rog* Raw Turbidity = 0.42 TU
               •O HEAD LOSS
           ——^ TURBIDITY
V)
V)
O
  10
UJ
X
                   -AY7
                                                 .08
                      .06
                                               -  .04  Q
                                               - .02
                                                    m
                                                    IE
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                10   14    IB    22

                        HOURS
         26
          30
34
       FIGURE  13 . HEAD  LOSS AND EFFLUENT

                  TURBIDITY  CURVES.  UNIT
                  ERD-2  RUN 79.
                          56

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  60
                       Average Raw Turbidity - 1.16 TU
  55
  50
  45
  40
tr
LJ
h-
UJ
LU
  30
  25
CO
(O 20
O
Q
<  15
LU
X
  10
                 HEAD LOSS

                 TURBIDITY
                                                       -» .36
                                                         .32
                                                         .28
                                                         .24
                                .20
                                                            Q

                                                            CD
                                .16
                                .12
                                .08
                                                         .04
                    10
14
   18

HOURS
22
26
30
                                                       34
        FIGURE  14 .  HEAD LOSS AND EFFLUENT TUR-

                      BIDITY  CURVES. UNIT  ERD-2

                      RUN  21.
                             57

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  64
  60
cr
LJ
< 56
                       Average Raw Turbidity = 0.66 TU
                 HEAD LOSS
          '——••  TURBIDITY
  62
Ld
LU
  48
CO
CO
3
Q

X
  44
                               I
10
                         14     18
                            HOURS
                                     22
26
30
                                                        .16
                                                        .12 13
                                                        .08 H
                                                           Q
                                                           CD
                                                        .04 ?5
34
        FIGURE 15  .  HEAD  LOSS  AND EFFLUENT   TUR-
                     BIDITY  CURVES. UNIT  ERD-2
                     RUN  34.
                             58

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properly designed filter septa,  two-step precoating might  not be necessary for
production of low initial effluent turbidities.

Operational Variations
The data listed in Tables 12 and  13 summarize the results  of the BIF and  ERD
runs and are used to compare sets of runs with similar treatment configurations.
Filter runs with the DE units were quite long when conducted to their respective
maximum head  loss differentials. Under  good  quality  effluent  production
conditions (effluent  turbidity 0.1 TU or less), filter run lengths of 30 to 40 hours
with  the BIF  unit and 60 to  70 hours with the ERD  unit  could  be achieved
easily. Therefore, filter runs for the  DE units were  limited  to a maximum of 24
hours to permit variations of treatment configurations.

Individual  head  loss  and  turbidity curves  for each  DE  run  are  provided in
Appendices D-3 and D-4.

Precoat Application
Several series of runs  were conducted in both the  BIF and ERD units utilizing a
single  level of DE for  the precoat. Substantial operational  and effluent turbidity
problems were encountered with this procedure.

The data from Tables  12 and  13  show the relatively high effluent turbidity levels
that resulted with the  single precoat application. In Runs 1T-14T and 1-17 in the
BIF unit,  average effluent turbidity results when using a single precoat, averaged
0.47,  0.18,  0.26,  and 0.35 TU.  In addition, Appendix C-3  shows  that  several
additional attempts at  filter runs in  the BIF unit were  aborted  shortly after
initiation,  due to initially high  effluent turbidity,  in all cases greater  than  1.0 TU.
Similar results were found when  a single  grade DE was used as a precoat in the
ERD units.  Runs 1A-6A and  1-27 produced  average effluent turbidities of 0.30,
0.22,  0.10, and 0.82 TU. As  with the BIF unit, several runs in the ERD  single
precoat  series  were aborted for reasons of initially high  effluent turbidity, again
greater than 1.0 TU, shown in Appendix C-4.

Results of the amphibole mass analysis  from the NWQL listed in Tables 12 and 13
show that a significant amount of DE was passing through the filter  septa  in both
the BIF and  ERD units upon application of  a  single precoat of  DE. This ac-
counted,^ part, for  the relatively high  effluent turbidity  results. These conditions
were particularly noticeable when the  single layer of DE involved was a relatively
fine  grade of DE.   It  is  probable  that  the openings  in  the  filter septa  used
                                      59

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 during  the pilot  study  were not designed to retain the finer grades of DE which
 were required to attain the low effluent turbidities desired.  For instance, Run 2T
 in the  BIF unit and Run 2 in the ERD units utilized Hyflo Super Cel as a precoat
 media,  a  relatively  fine grade  of DE, with  resultant  average  effluent turbidity
 levels of 0.65 and 0.56  TU, respectively.

 Initially,  in  an attempt to prevent the DE passage through the filter septa and
 improve the effluent turbidity  levels, two  grades of DE, fine  and coarse, were
 mixed  and   then  coated  with  alum  or polymer.  Results  from  Table  12  for
 the BIF unit indicate that some success was achieved. Average  effluent turbidity
 levels dropped from 0.47 TU to 0.18 TU in the  case of Runs 8T-14T and  Run 8
 in which an anionic polymer, A-23, was added to a precoat composed of a  fine
 and  a  coarse DE.  Similarly, results from  Table 13 for the ERD  units indicate
 average effluent  turbidity  reductions  from 0.30 to 0.10TU  in  Runs 21-27 in
 which alum  was added to a  precoat composed  of a fine and a coarse DE.

 The  runs conducted implementing  the above two steps produced a serious  opera-
 tional  problem  involving backwashing of  the  filter septa.  Single  step  precoat
 applications  to which  coagulants  were added so coated the  filter septa with the
 precoat that ordinary  backwashing procedures were ineffective in removing the
 solution in preparation for a subsequent run.

 The  two-step precoat procedure was used in a series of runs with the BIF unit. In
 some runs, a medium coarse DE such as FW-20 or Celite 503 was used as the first
 precoat step  while a very coarse DE such as FW-50 or Celite 545 was used  in the
 remaining runs as the  first  precoat step. Polymers were added  to both the first
 and  second   precoat steps  in some runs.  Although the average effluent  turbi-
 dities were somewhat  improved  by the  addition  of polymers, the operational
 problem of  the precoat adhering to the filter septa during backwashing still per-
 sisted.  Runs  in which  either coagulants  or polymers  were added to only  the
 second  step  of the precoat  eliminated this  operational problem.  In addition,
average  effluent turbidity  results were improved to levels  as  low as 0.10 and
 0.08 TU in some chemical-precoat combinations.

The  series of runs in  the  ERD  units utilizing  the two-step precoat  procedure
produced  even better results. The  problem of the precoat adhering to the filter
media  was  eliminated  and  average effluent turbidities were reduced to  levels
consistently   below 0.10TU  in almost all chemical-precoat  combinations.  In
addition to  the elimination of the aforementioned operational  problem and  the
passage  of DE through  the  filter septa, asbestiform fiber removal results became
                                     60

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more  consistent  between the three reporting laboratories, especially in those runs
in which optimum concentrations of chemicals were utilized.

One other variable that was considered in the precoat application process was  the
amount of weight of precoat per square foot of filter surface area. The initial runs
conducted with  the BIF unit  (Runs 1T-11T) used  0.48  kg/m2  (0.1  lb/ft2). The
precoat was increased to 0.73 kg/m2 (0.15  lb/ft2)  in Runs 12T-14T  and 1-24 in
an  effort to build a more cohesive  precoat and  prevent DE passage  through  the
filter  media. This same  amount, 0.73 kg/m2  (0.15 lb/ft2), was also used in  the
ERD  units in Runs 1-27.  It was found, however, that during the initial phases of
the runs, the  effluent turbidity was quite high and required as  long  as 1 hour to
be  reduced  to a consistent and acceptable level. The amount of DE in the precoat
was then increased to 0.968 kg/m2  (0.20 lb/ft2) in a successful effort to reduce
the initially high effluent turbidity. The results of this practice are  reflected in the
data  from  Runs 25-100  in the BIF unit and Runs 28-86 in the ERD  units. It  was
also found  that the stability and integrity of the precoat were enhanced  in that
hydraulic surges during  the  initial stages of  the  filter run would not cause the
precoat  to rupture. The amount  of precoat used with the BIF unit was increased
to  0.25 lb/ft2 in Runs 101-122.

Body Feed
Body feed  application in  the BIF  unit was generally  divided into two major
groupings. Runs 1-61 utilized  three basic grades of DE  in varying concentrations
without the addition of any  chemicals. Runs 62-122 utilized  these same grades in
varying  concentrations, with the addition of chemicals such as alum  and soda ash
and a cationic polymer, Catfloc  B.  The three basic grades of DE utilized in Runs
 1-61  included fine grades such as FW-6, Celite 512 or Speedflow, medium grades
 such as FW-12  or Hyflo Super Cel, or medium  coarse grades such as Celite  503.
 The  initial selection of a fine grade DE for Runs  1T-14T,  1-16  and 46-61  was
 made to produce a  finished water with a  low effluent turbidity level. However,
 with the discovery of the DE bleed-through  problem discussed previously, and in
 an effort to  lengthen the filter runs by reducing the rate of head loss buildup, a
 change  was made to a coarser or medium  grade DE in Runs 17-42. This change,
 in combination with the two step precoat  process, was successful in reducing the
 passage of  DE  through the filter septa and preventing the accumulation of DE  on
 the septa during the backwash procedure.  Data  from Table 12 have already been
 cited as showing the subsequent improved effluent turbidity levels.
                                      61

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 The rates  of  body  feed  application in Runs  1-61  varied from approximately
 40  mg/1 to 340 mg/1 in the case of fine media, 60 mg/1 to 300 mg/1 for medium
 grade media, and 370 mg/1 for  the medium  coarse media. The general effect of
 increasing the  dosage rate in all  cases was to  decrease the  filter run length due to
 a faster rate of head  loss  buildup and increase the level of effluent turbidity re-
 moval. The increase  in rate of head loss buildup with an increase in body feed
 rate would indicate that the body feed rates were above  the optimum  feed rate.

 Varying the grade and dosage of body feed DE was accomplished in BIF Runs
 62-122 in which chemicals were added to the body feed.  A fine grade of DE was
 used with alum and  soda  ash in Runs 62-78, 107-109, and 111-112. Dosage rates
 varied in this  series  of runs  from approximately  15 mg/1 to 110 mg/1.  The data
 show  the general decrease in filter run lengths with an  increase in dosage rate of
 body  feed  DE. For example, in Runs 107-109,  body feed dosages of Celite 512
 varied  from  30 mg/1  to   100 mg/1,  respectively,  while  the  filter run  lengths
 decreased  from  20.5  hours to  8.5  hours. This same observation was made in
 Runs 104-106  in which Hyflo   Super Cel, a slightly  coarser grade of DE, was
 used as the body feed. Filter run lengths varied from 22 hours with a dosage rate
 of 12 mg/1 to 9 hours with a dosage rate of 84 mg/1.

 The concentration  of body feed in  the  ERD units  varied  considerably, ranging
 from 30 mg/1 to 200 mg/1 for the finer grades and 25 mg/1 to 100 mg/1 for the
 coarser grades  such as Celite 545  and FW-50. It was found that the coagulants
 and  polymers used in  the precoat and  body  feed  processes produced  a greater
 effect  on the effluent turbidity and the rate of head loss  than did the grade and
 amount of body feed. This was probably due  to the greater pressure  differential
 produced across  the  filter media in  the  ERD units  that  tended  to dampen the
 effects on  the  head loss produced by the various grades  of media. In  addition,
 contrary to the operation  of the BIF  unit, effective filter  area of the ERD units
 tends to increase with increasing  amounts of DE applied as body  feed due to the
 cylindrical  shapes of the septa. Consequently,  the rate of head loss buildup would
 not be as rapid  for these particular units.

 Length of filter run of the DE units appeared to be affected more by changes in
raw  water turbidity than was the filter run length on the granular units. However,
filter run length of the DE units was also affected by  the amount  of body feed
used in proportion to the raw water suspended solids. If the body  feed rate is not
increased sufficiently whenever an increase in raw water suspended  solids occurs, a
higher  rate of head loss buildup will occur, with a resultant reduction in filter run
                                    62

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length. If the body feed is increased  too much in proportion to the suspended
solids,  excessive  thickness will be added to the filter cake, again resulting in rapid
head loss buildup and a shorter filter run. Optimum body feed rates, based on the
suspended solids concentration of the  raw water, were not used during the pilot
filtration study.

Chemical Additions
Two series of runs were conducted utilizing an anionic polymer, A-23, introduced
to the total precoat in Runs 36-41 and to the second step of the precoat in Runs
79  and  80.  Comparatively better effluent turbidity  levels  were achieved, with
averages  of 0.15 and 0.22 TU. In addition, it was found that introduction of the
polymers to the second step of the precoat eliminated the backwashing problems
previously  noted.  Subsequent runs were then conducted utilizing this procedure.

Alum  was used in two series of runs in which it was introduced in the  second
precoat  step.  These  were Runs 42, 46,  47,  and 49-51 and Runs  52-57 which
produced average effluent turbidity levels  of 0.27 and 0.29 TU. An additional two
series  of runs were conducted in which soda ash was introduced with the alum.
This procedure  was designed  to maintain  the pH of the precoat solution   above
7.0  so that aluminum  hydroxide would form on the DE precoat.  The data
from these  two series, Runs  58-61 and 89-103, show average effluent turbidity
levels  of 0.35 and  0.23 TU.

The addition  of alum and soda ash to the second precoat step and  to the body
feed  was investigated in Runs 62, 104-109,  and 120-122.  It was felt that the
initial positive  charge  resulting  from the  addition of alum and soda ash only
in the second step of the precoat was counteracted by the addition of the DE in
the  body feed. Constant addition of the body feed would  eventually produce a
net  negative charge in  the filter cake. With the addition of  alum and soda ash in
the  body  feed,  a filter cake with  a net positive charge  could be  maintained.
Following this procedure, average effluent  turbidities of 0.15 TU were produced.

In  Runs 75-78,  111, and 112, an anionic polymer, A-23, was introduced in the
second precoat  step  and alum and soda ash were added to the body feed.  In the
series  in which a  very coarse DE was used  in the first  step of the precoat, ex-
tremely  good turbidity results were achieved, with an average effluent turbidity of
 0.10TU.

 A cationic polymer, Catfloc B, was introduced to the raw water prior to filtration
 in  Runs 82-84 and 86-88. Effluent turbidity levels averaged 0.23 TU.  In Runs 110
                                      63

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 and 113-119, this procedure was carried a step further with the addition of alum
 and soda ash to the second  step of the precoat. Extremely good effluent turbidity
 results, averaging 0.08 TU, were recorded.

 A program of chemical addition similar to  the one followed with the BIF unit
 was conducted  utilizing  the  ERD units.  A single run  was conducted, with  an
 anionic polymer, A-23,  added to the second precoat step,and alum and soda ash
 added to  body  feed. Excellent results  were achieved, with an average  effluent
 turbidity of 0.05 TU.

 Three series  of  runs were conducted using alum without polymers. In the first,
 Runs 28-37, alum  was  added only  to the second step of the precoat. The data
 show that  effluent  turbidities of 0.12 TU were achieved. As in the case with the
 BIF unit, soda ash was added to the alum in the next series, Runs 38-44, 54-60,
 and  62-66, to promote  the  alum coating process. In  this series of runs, the
 effluent  turbidities  averaged 0.10TU. In the final series of runs in this grouping,
 alum and soda ash were added both to the second precoat  step and to the body
 feed. Effluent turbidities were extremely low, averaging 0.06 TU.

 Runs 45-51, 73-76, and  78-81  utilized a cationic polymer, Catfloc B, added to the
 raw  water  prior  to  filtration. In the  first series, Runs 45-51, an effluent  with an
 average turbidity of 0.12TU was produced.  In Runs 73-76 and 78-81, with the
 addition of alum and soda  ash to the  second  precoat step, the average  effluent
 turbidity was further reduced to 0.06 TU.

 Backwash Solids

 The  relationship  of backwash solids to sludge  volume is presented in Table 14.
 The  data  given  is  based upon results  of settleable  solids tests  performed  on
 samples of backwash water from the BIF and  ERD units. Sludge production shown
 in the table  is in terms of  sludge produced per  1000 gallons of water  treated.

 TABLE 14.   RELATIONSHIP OF BACKWASH SOLIDS TO SLUDGE VOLUME
              DE UNITS
Pilot
Unit
BIF
BIF
ERD-2
Run
11-4
121
85
B.W. SS,
lb/1000 gala
2.05
0.90
0.93
B.W. SS,
mg/1
89,156
20,112
14,504
Cone. @
60 min,
%
36.4
15.5
90.6
Sludge
volume,
gal/ 1000 gal
0.68
0.70
0.122
a Based on theoretical solids production

                                     64

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COMPARISON OF TURBIDIMETERS
Parallel turbidity readings  on the effluent from the MM-2 unit were made using
the Hach  2100A and the Hach  1720 turbidimeters. Typical data from the 2100A
and 1720 units are plotted on Figure 16 and all the data collected with the units
are tabulated  in Appendix H. Readings  obtained  with the 1720 unit correlate
reasonably well with those  obtained with the 2100A turbidimeter.

Parallel readings  on  the raw  water  were taken with  both Monitek turbidimeters
and the  Hach  Model 2100A  turbidimeter.  Readings  on  the  Monitek units were
very erratic and did  not correlate to readings obtained with the Hach 2100A unit
until after one of the Monitek units was disassembled, the sight glass cleaned, and
the unit reassembled with an air purge connected. The air purge had  been tried
previously with no effect on the performance of the units, apparently because the
sight  glass was so  dirty that the source light was being deflected as it passed
through the sight glass.

After the. sight glass was cleaned  and raw water readings on the Hach 2100A and
the  Monitek  appeared  to correlate, parallel  readings  were also taken  on  the
finished  waters from the  ERD  unit and the  MM-1  unit. Typical data from the
Hach  2100A  and the Monitek  unit  are presented on Figures 17, 18, and 19 and
the  data  are  tabulated  in Appendix  H.

All turbidity  measurements  discussed in comparisons  of the  various  pilot filter
units tested will refer to data  collected with the Hach 2100A unit.
                                      65

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                          99
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6
         FIGURE 18 .TYPICAL ERD  FILTERED  WATER

                    TURBIDITY  READINGS OBTAINED WITH

                    HACH 2100 A AND MONITEK TURBIDI-

                    METERS.
                          68

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                                           I
                                           8
                                              a
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q

d
FIGURE 19 . TYPICAL  MM-I  FILTERED WATER

          TURBIDITY READINGS  OBTAINED

          WITH HACH 2IOOA  AND  MONITEK

          TURBIDIMETERS.
                 69

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                                SECTION VII

                                DISCUSSION

 RELATIONSHIP  OF TURBIDITY,  ASBESTIFORM  FIBER COUNT  AND
 AMPHIBOLE MASS IN RAW WATER

 Figures 20, 21, 22,  and 23 present the relationships of raw water turbidity, ORF
 amphibole  and chrysotile fiber  counts,  and NWQL  amphibole and  suspended
 solids concentrations, respectively.  It was determined from the raw water asbesti-
 form data that no discernible  link was evident between the  raw water turbidity
 and the asbestiform  levels.  Appendices E, F and G give asbestiform analytical data
 reported by ORF, NWQL and UMD, respectively.

 GRANULAR MEDIA FILTRATION

 Asbestiform Fiber Removal

 In  terms  of fiber removal, either  amphibole or chrysotile, a test run has been
 considered successful if BDL  or a value near BDL ( < 40,000  f/l)was reached  in
 the  filtered water.

 Table 15  summarizes the ORF  data on  amphibole and chrysotile removal for the
 MM-2  runs and shows that  32 of 34  MM-2 runs  for amphibole removal were
 successful. The two unsuccessful runs (54 and 57) were made early in  the study
 and  used  dual media and single-stage mixing, which were  not as  effective  as
 tri-media and two-stage mixing.  Table  7  presented data  on  MM-1 and indicated 21
 of 23 runs achieved BDL or near it for amphibole removal, but only 2 of 23 were
 successful  for chrysotile removal. There appears to be evidence that contamination
 of samples may have occurred  either in the process of collection or perhaps  in
 sample preparation in the laboratory.  The effects of long  storage (2-7 weeks) on
 the  detection  results are  not definitely known but this, too, might  have  had a
 bearing on some  of the fiber counts. Hopefully, future studies  will remove any
 uncertainties and  provide  more reliable chrysotile data. In spite  of these points,
 certain evaluations on treatment effectiveness for chrysotile removal can be made
 and are presented in Table 16.

 To  achieve BDL, or  close to  BDL  for chrysotile, it  was found that the  minimum
alum dosage should be approximately 15 mg/1. Although MM-2 Runs 96, 105 and
 122  prove to be exceptions to this by reaching BDL or near it with alum dosages
less than 15 mg/1, Runs 53,  54, 55,  57, 61, 71, 99, 101, 111 and 131  (which used  •
                                    70

-------
      4.0
      3.0
 Q Q
 8
  CD
£ cr
LL) ID
   o:
   LJ
   I-
      2.0
 Q <
   cr  I.O
                     1.0          2.0          3.0

               AMPHIBOLE  FIBERS /LITER X  I06
               ONTARIO  RESEARCH  FOUNDATION
                                                           4.0
FIGURE 20. RELATIONSHIP  BETWEEN RAW  WATER  TURBIDITY  AT DULUTH
          LAKEWOOD  INTAKE AND  ORF AMPHIBOLE  FIBER COUNTS.
                              71

-------
          4.0
         3.0
     z >•
     o m
       s
    Q <
       o:
         2.0
                       1
             I
                       1.0
2.0
                                               3.0
                        4.0
                CHRYSOTILE  FIBERS/LITER  X  |Q6
                ONTARIO RESEARCH  FOUNDATION
FIGURE  21 .   RELATIONSHIP BETWEEN RAW WATER TURBIDITY AT DULUTH
            LAKEWOOD  INTAKE  AND ORF CHRYSOTILE  FIBER COUNTS.
                             72

-------
        4.0
        3.0
   Q Q
   O m
    _l —
      UJ
    IS
    §1
      cr
        2.0
                      I
1
                     O.I          0.2         0.3         0.4
             AMPHIBOLE  FIBER  CONCENTRATION  (mg/l)
               NATIONAL  WATER  QUALITY  LABORATORY
FIGURE 22 .  RELATIONSHIP  BETWEEN  RAW WATER  TURBIDITY AT DULUTH
           LAKEWOOD INTAKE AND NWQL  AMPHIBOLE MASS CONCEN-
           TRATION .
                            73

-------
         4.01—
    Uj ^

    5    30
    
-------
TABLE 15.   GRANULAR  MEDIA  FILTRATION  (HH-2)  AHPHIBOLE AND CHRYSOTILE  REMOVAL  (ORF DATA)


Run Date
1 H/19
7 4/25
37 5/16
50 5/30
53 6/4
- 54 6/6
55 6/11
57 4/13
61 6/17
71 6/24
76 6/28
78 7/3
96 7/19
99 7/23
101 7/25
105 7/30
106 7/31
107 8/1
109 6/6
III 8/8
113 8/13
114 8/15
118 8/20
119 8/23
122 8/28
124 8/30
126 9/4
128 9/6
131 9/10
133 9/11
137 9/13
133 9/16
139 9/17
140 9/19
Filter
Rate
gpm/ft2
4.96
4.26
3.86
4.01
4.15
1.97
1.86
6.31
6.77
6.86
1.79
3.15
3.75
4.41
4.55
4.41
4.17
3.20
3.38
4.47
3.88
1.97
4.01
4.24
4.33
3.92
4.00
4.12
6. 18
5.98
3.98
4.29
4.35
3.85
6 Alum dosage probably
Cheni ca)
Turbidity

Amphi bole

Chemicals (mg/l)
FeCl3(8.22). C-3l(0.il8)
FeCI3(8.6l), C-3IJ0.626)
Alun(l8.62), N-I7J0.24)
Alumjie.O), 985-NJ0.054)
Alunjll. 19), 985-N(0.053)
Alun(l2.8), 985-N(0.052)
Alun(l3.72), 985-N(0.050)
A1um(M.I7), 985-N(0.05l)
AlunjlO.25), 985-K(0.037)
Alun (7.10), 985-0(0.079)
Alum(26.89), 98S-NJO.I59)
Alum(|iL66), 985-KJ0.079)
Alum(6.98), 985-N(0.060)
Alun(8.77), 985-NJ0.029)
Alun(9.99), 98E-N(0.0!3)
Alun(l0.97), 985-H(0.029)
Alira(20.97), 985-NJO.I22)
AIun(l6.l9), 985-HJ0.04)
Alum(l5. 10), 985-N(0.043)
Aluffl(ll.73), 985-NJ0.034)
Alum(l5.30), 98£-N(0.04l)
Aluro(l8.93-), 985-HJ0.042)
Alum(l5.43), C-B(0.56), A-23(0.65)
Alun(l4.24), 985-N(0.0>}2), A-23(0.28)
Alurajl 1.58), 985-11(0.049)
A-23JO.I60), Alun(l4.93), 965-11(0.064)
A-23(O.I58), Alun (16.95), C-3IJO.S67)
A-23(O.I24), Alum(l3.38), 985-NJ0.060)
Alum(l3.36), 985-NJ0.053)
Alum(24.56), 985-NJ0.077)
Alum(l9.66), C-3I(0.790)
Alun(l4.62). A-23(O.I26), 985-K(0.065)
Alum(l4.70), A-23JO.I23), C-3I(0.622)
Alum(l4.02), 985 11(0.066)
too low for effective chrysotile removal


Media
Dua
Dua
Dua
Dua
Dua
Dua
Dua
Dua
Dua
Dua
Dua
Tri
Trl
Tri
Tri
Tri
Tri
Tri
Tri
Tri
Tri
Tri
Tri
Tri
Tri
Tri
Tri
Tri
Trl
Tri
Tri
Tri
Tri
Tri


Stage
Mixing











2
2
2
2
2
2
2
2
2
2
2
2
2
in-lin
in-1 i n
in-1 in
in-lin
in-1 in
in-lin
in-1 in
2
2
2


Fibers x I06/l
Raw
0.304
0.348
2.61
1.43
1.74
1.5
1.0
0.48
0.61
1.0
0.91
0.56
0.52
0.54
O.I!
0.11
0.33
0.22
0.6
0.06
0.13
0.09
0.30
0.72
0.39
0.78
1.61
0.72
0.6
0.3
0.02
0.9
0.2
0.6


Filt.
BDL
BDL
BDL
BDL
BDL
0.09
BDL
0.15
0.04
0.02
BDL
0.02
0.02
BDL
BDL
BDL
BDL
BDL
BOL
BDL
BDL
0.02
0.02
BDL
BDL
0.02
BDL
BDL
BDL
0.02
0.02
0.02
BDL
BDL


Chry«otil«
Fibers x I0«/l
Raw
0.217
0.174
1.35
1.83
2.91
2.3
1.6
0.41
2.15
3.9
3.35
3.57
0.35
0.09
1.43
O.I 1
0.22
0.15
0.3
0.09
0.2
0.17
0.72
0.44
0.48
0.33
0.3
0.39
0.5
0.3
0.06
O.I
0. 1
0.09


Filt.
0.04
0.348
0.174
0.913
1.87
0.09
2.3
2.02
0.37
0.98
0.52
0.5
0.04
0.20
0.15
0.04
BDL
BDL
8DL
0.09
1.4
0.22
2.1
0.28
0.04
0.30
BDL
0.37
0.6
0.3
O.I
0.3
O.I
0.3


Filter Sun
Hrs.
14.6
15.0
12.2
23.7
24.0
67.3
33.1
15.6
11.6
12.8
9.4
23.7
7.8
17.9
14.7
25. 8
4.0
30.8
34.3
25.6
22.6
£8.6
20.2
21.8
19.9
19.6
17.8
21.0
10.0
7.4
9.6
21.8
21.4
31.9


Tin* to
Sample
Hrs.
6.5
4.5
9.8
7.5
4.7
25.6
26.9
13.5
4.0
4.3
4.9
3.3
2.1
7.4
13.1
4.3
2.4
17.9
23.5
9.9
22.3
45.7
1.9
18.5
3.7
3.7
9.6
8.7
2.9
4.3
5.3
1.9
I.S
i.e


Avg Filtered
Turbidity
T.U. Fenarkt
0.4
0.3
0.2
O.I
O.I
O.I
O.IS
0.25
O.IS
O.IS
0.07
O.I
O.IS
O.I ,d,f
0.15
0.10
0.06
0.08
0.07
0.09 ,d
0.06 ,d,f
0.06 ,f
0.10 ,f
0.08
0.06
0.07
0.06
0.07
0.07 a,c
g
0.07 c,d
0.06 d.e
0.07 d,«
0.06 b.d


breakthrough in less than 9 hours
d
8 A-23 interference wi
.


removal sat

sf actor i ly














     Contamination of sanple or laboratory problems suspected
     Great variation in final turbidity - poor run

-------
TABLE  16.      GRANULAR MEDIA FILTRATION - COMMENTS ON
                 CHRYSOTILE  REMOVAL (MM-2)
Run
Chrysotile
106
107
109
126
Chrysotile
96
105
122
Runs with
37a
soa
76a
78b
113C
114°
137C
139C
140°
118C
119C
124C
138°
Filt. Rate
gpm/ft2
Runs Which Achi
4.17
3.20
3.38
4.00
Chemicals Media
eved BDL
Alum (20.97)
985-N (0.122) Tri
Alum (16.19)
985-N (0.04) Tri
Alum (15.10)
985-N (0.43) Tri
Alum (16.95)
A-23 (0.158)
C-31 (0.567) Tri
Mixing
2 Stage
2 Stage
2 Stage
In-Line
Filtered
Chrysotile
(Fibers x 106/1)
BDL
BDL
BDL
BDL
Runs Which Achieved 0.04 x IO6 fibers/1
3.75
4.41
4.33
Similar Treatment
3.86
4.01
1.79
3.15
3.88
1.97
3.98
4.35
3.85
4.01
4.24
3.92
4.29
Alum (6.98)
985-N (0.060) Tri
Alum (10.97)
985-N (0.029) Tri
Alum (11.58)
985-N (0.049) Tri
Which Did Not Achieve Desired Goal
Alum (18.62)
N-17 (0.24) Dual
Alum (16.0)
985-N (0.054) Dual
Alum (26.89)
985-N (0.1 59) Dual
Alum (14.66)
985-N (0.079) Tri
Alum (15.3)
985-N (0.041) Tri
Alum (18.9)
985-N (0.042) Tri
Alum (19.66)
C-31 (0.790) Tri
Alum (14.7)
C-31 (0.622)
A-23 (0.125) Tri
Alum (14.02)
985-N (0.066) Tri
A-23 (0.65)
Alum (15.43)
Catfloc B (0.56) Tri
A-23 (0.28)
Alum (14.24)
985-N (0.042) Tri
A-23 (0.160)
Alum (14.93)
985-N (0.064) Tri
A-23 (0.126)
Alum (14.62)
985-N (0.065) Tri
2 Stage
2 Stage
In-Line
Single
Single
Single
2 Stage
2 Stage
2 Stage
In-Line
2 Stage
2 Stage
2 Stage
2 Stage
In-Line
2 Staee
0.04
0.04
0.04
0.174
0.913
0.52
0.50
1.4
0.22
0.1
0.1
0.3
2.1
0.28
0.30
0.3
a Utilized dual media and single stage flash mixing.
bNo apparent reason for not achieving desired goal.
 Alum dosage too low.
                                      76

-------
low  alum  dosages and  985-N)  support this statement in that BDL  was  not
reached.  Runs 37, 50, and  76, although utilizing alum in excess of 15 mg/1, were
not successful probably due to the use of single stage flash mix and perhaps dual
media. Run 78  did  not achieve BDL, and there are no apparent reasons why it
did not. Runs  113,114,  137, 139, and  140 failed to achieve BDL  principally as a
result of the  effect  of  low chrysotile in the influent. When  influent  chrysotile
values are  low,  differentation between influent and effluent values  is apparently
lost. Finally, Runs 118,  119,  124, 138, and   139 were not successful due to the
suspected interference of A-23 and alum. This  apparently was overcome in  Run
126  by  the presence  of C-31 where an effluent chrysotile of BDL was achieved.
In Run  118,  Catfloc B was unable  to offset  the  substantial dosage of A-23.  Run
126  employed three in-line mixers arranged in series, with three separate chemicals
fed,  one upstream from each mixer.

Turbidity Removal

Table 15 shows filtered water average turbidity achieved in all MM-2 runs where
asbestiform analyses were made. Raw water turbidity usually was quite low during
the  pilot  plant  study, generally less than 1.0 TU and only rarely increasing to
about 4 TU.  Filtered water turbidity averages  in  Table  15 reached  a  maximum
of 0.4 TU for Run 1  but decreased steadily  as experience led  to  better chemical
treatment,  mixing, and tri-media filtration. As shown in the table, the  average final
turbidities  quickly dropped  to less than 0.2 TU  and during the last  16  runs,
nearly all values were less than  0.1  TU. It is felt that granular filtration employing
tri-media,  together with proper chemical treatment  and  mixing, is capable of
producing consistently a filtered water turbidity less than 0.1 TU.

Although turbidity removals were approximately the same in runs where alum was
used  as  the  coagulant, compared  to runs in which FeCl^ was  used,  filter  run
lengths  were  consistently  longer in those runs where  alum was  used.

Design Filter Rate

Table 17 shows data  on 25 additional MM-2  runs where no fiber removal analyses
were made plus  6 runs with fiber analyses  data.  All  runs were  made at about
        ^\
5 gpm/ft   or  higher.  This  information has significance when  interpreted on the
basis of Figure 24 which shows the relationship between filtered  water turbidity
and  amphibole fiber count. This figure clearly shows that when a turbidity of  0.2
TU or less was achieved, the corresponding amphibole count was 0.02 x 10° f/1 in
the vast  majority  of the samples.  This fiber  level was reported as BDL by  ORF.
                                     77

-------
TABLE 17.   GRANULAR MEDIA FILTRATION (MM-2) FILTER RATES
           5 gpm/ft2 AND GREATER
Run
Group
30
51
58
59
60
62
63
64
65
66
67
68
69
70
72
73
74
85
86
87
88
89
129
130
132
Group
1
57
61
71
131
133
Date
Filter Avg. Turb.
Rate Treated Water
gpm/ft^ TU
Filtered Water
Amphibole Chrysotile
Fibers x 10°/1
1 (No Fiber Analysis Made)
5/10
5/31
6/13
6/14
6/14
6/18
6/18
6/19
6/19
6/20
6/20
6/20
6/21
6/21
6/25
6/25
6/25
7/10
7/11
7/11
7/12
7/12
9/9
9/10
9/11
2 (Fiber Analysis
4/19
6/13
6/17
6/24
9/10
9/11
5.28
5.09
5.33
5.65
6.82
6.84
6.91
6.86
6.87
7.82
6.82
6.89
7.47
6.78
6.17
6.64
6.91
4.85
4.91
4.94
4.86
4.79
6.16
6.09
5.97
Data Available)
4.96
6.31
6.77
6.86
6.18
5.98
0.09
0.43
0.10
0.13
0.13
0.19
0.17
0.18
0.14
0.12
0.12
0.15
0.22
0.30
0.12
0.15
0.35
0.12
0.08
0.14
0.13
0.08
0.12
0.07
0.16

0.40
0.25
0.15
0.15
0.07
—
_
— —
— —
— — .
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— -

BDL 0.04
0.15 2.02
0.04 0.37
0.02 0.98
BDL 0.50
0.02 0.30
                             78

-------
            1.0
   0.14
   0.12
   0.10-
₯.  0.08


CO

-------
For purposes of this study, final fiber counts of 40,000 f/1 or less, or BDL were
considered to be successful. As shown on Figure 25, the  same relationship was not
apparent between effluent turbidity and chrysotile fiber  count.

Table 17 shows under Group  1  that  22 of 25 runs at filter rates of 5 gpm/ft^ or
greater achieved an average  turbidity of  0.2  TU or less and quite likely would
have reached BDL or close  to it, had asbestiform analyses been made. This data
suggests that, as an initial operational guide,filter runs be terminated when turbi-
dities reach 0.2 TU.  Because some  of the runs should have  been  terminated
earlier,  this would  have  avoided some  high  turbidity data  and could  have
produced additional successful runs.

Runs 1, 61, 71, 131, and 133 shown  in Table 17 under  Group 2 were operated at
                     ^
filter  rates  of  5 gpm/ftz  or  greater and were successful  for amphibole removal.
                                    •^
The  only other run at above 5 gpm/ftz (Run 5 7)was unsuccessful for  amphibole
removal and this is attributed to dual  media and  single-stage mixing. On this basis,
5 of  6  runs at high filter rates where fiber  removal analyses were made, were
successful for  amphibole  removal.  One  of the  6 runs  under Group  2 was suc-
cessful for chrysotile removal. Poor chrysotile removals may have been due to low
alum dosage, dual media, and single stage mixing  in Runs 57, 61 and 71.  Low alum
dosage could have been the  reason  in Run 131.  Possible sample  contamination,
long storage, or laboratory problems might explain why  Run 133 was unsuccessful
for chrysotile removal.

Based  on the  above data,  it  is reasonable  to conclude that a  filter rate of
        ^
5 gpm/ftz  with proper chemical  treatment  and  good  mixing should 'achieve
excellent results (BDL or near it) for  amphibole fiber removals.

DIATOMACEOUS EARTH FILTRATION

Asbestiform Fiber Removal

Table 18 shows fiber removal data for selected BIF (vacuum) DE runs. Three runs
(8,  10T, and  12T)  employing  A-23 polymer  in one  precoat  step treatment
achieved success for amphibole  removal in two of the  runs but in only one for
chrysotile removal. Four runs (37, 70, 72, and 79) used A-23 in the second  pre-
coat step and all runs were  successful for amphibole removal.  Two of the four
runs reached BDL or near it for chrysotile removal.  Runs 77 and 111  used A-23
in the second  precoat step but  in addition added alum and soda ash to the body
feed.  Both runs  were successful for amphibole  removal, but  neither was suc-
cessful  for  chrysotile  removal.   Runs 82,  84,  and  88  used  Catfloc B
                                    80

-------
         23x10°

          187 xlO6
Z.OxlO6
          2.1 » IO
  1.6
  1.4
  1.2
en
a:
a
UJ
O 0.8
CO
>-
o:
x
o


Z 0.6
UJ
u.
UJ
  0.4
  0.2
             0.2
0.4
0.6
0.8
1.0
      BDL'S
                EFFLUENT TURBIDITY, TU
     FIGURE 25 .EFFLUENT  TURBIDITY VS. CHRYSOTILE

                 FIBER COUNT GRANULAR MEDIA.

-------
TABLE 16.   VACUUM (BIF) AND PRESSURE (ERD) DIATOHACEOUS   EARTH FILTRATION SELECTED FILTER RUNS (ORF DATA)
Run
Date
Vacuum
8 5/16
IOT
121
37
79
70
72
no "
OO
to '"
82
84
88
113
116
117
h8
Pre!
11
73
78
79
45
46
48
49
51
5/7
5/9
6/24
8/1
7/19
7/23
7/30
9/6
8/6
8/8
8/13
9/9
9/11
9/13
9/16
syre
9/6
9/9
9/13
9/16
7/30
8/1
8/6
8/8
8/13
Filter
Rate
jpm/ft*
0.948
1.035
0.979
0.866
0.877
0.925
0.920
0.958
0.946
0.818
0.826
0.914
1.002
0.862
0.330
0.826
.108
.146
.093
.092
.01
.087
.261
.266
.059
Feed To
Raw Mater
lbs/1000 gal

	
- - - .
	
....
	
	 .

....
Cat Floe 8(0. Oil)
Cat Floe 8(0.0016)
Cat Floe 6(0.0032)
Cat Floe 6(0.0024)
Cat Floe 8(0.0046)
Cat Floe 6(0.0036)
Cat Floe 6(0.0049)
...
Cat Floe 8(0.0047)
Cat Floe 8(0.0050)
Cat Floe 6(0.0028)
Cat Floe 8(0.0040)
Cat Floe 8(0.0037)
Cat Floe 8(0.0044)
Cat Floe 8(0.0044)
Cat Floe 8(0.0057)
Fir.t Precoat
Ibj/IOOO gal
FW-50(0.079), FW-6(0.039). A-23(0. 000001 . 18)
512(0.070), A-23(0. 000002.1)
Speed flow (0.138), A-23(0. 000004. 1 )
503(0.174)
546(0.066)
FW-20(0.099)
503(0.063)
546(0.063)
FW-50(0. 166)
645(0.051)
546(0.114)
545(0.036)
FW-50(O.I09)
FW-50(0. 131)
FM-5P(O.I30)
F»-50(0. 141)
FW-50( 0.067)
FW-50J0.068)
FW-50(O.III)
FW-50( 0.077)
545(0.036)
546(0.054)
545(0.050)
545(0.030)
FW-50(0.066)




FW-6(O.I74)
545(0.056),
512(0.099),
512(0.063),
545(0.053),
512(0.111),
512(0.051)
Second Precoat
lbi/1000 gal
. - - -
....
_ _ _ •_
A-23(0.000007.0)
A-23(0. 000002. 82)
A-23JO. 000001. 98)
A-23JO. 000001. 89)
A-23(0.000002.67)
A-23(0.000003.32)

Super Cel (0.114)
612(0.036)
512(0.072),
612(0.088),
.512(0.086),
'512(0.094),
512(0.067),
512(0.068),
512(0.111),
512(0.077),
512(0.036)
512(0.054)
512(0.050)
Super Cel(0
Super Cel(0

Alum(0.0060), Soda A»h(0.0040)
Alum(0.0096), Soda Ath(0.0048)
Alum(0.0095), Soda A»h(0.0048)
Alum(O.OIO), Soda Asn(0.0052)
A-23( 0.000002. 02)
Alum(0.0074), Soda Ash(0.0037)
Alum(O.OI2), Soda Ash(0.006l)
Alum(0.0085), Soda Ash(0.0042)



030)
066)
Body Feed
lbi/1000 gal
FV-6(0.550)
512(0.483)
512(0.51!)
FW-6(0.677)
512(0.577)
512(0.243)
512(0.174)
512(0.213), Alun(O.OI2), Soda Ath(O.OOSI)
512(0.229). Alum(0.025), Soda A«h(O.OI3)
512(0.306)
512(0.469 )<
FW-50(0.877)
Super Cel (0.952)
6I2(0.4CO)
Aqua Cel(0.58B)
Aqua Cel(l.29l)
512(0.233). Alun(0.026), Joda A.h(O.OI3)
Super Cel (0.171)
512(0.407)
Aqua Cel (0.228)
545(0.486)
545(0.882)
545(0.351)
FW-SO(0.48t)
FW-SOJ0.676)
Aiwnibola
Fiben > IC*/|
Raw
2.61
0.522
0.870
1.0
0.72
0.52
0.54
0.11
0.72
0.6
0.06
0.13
1.0
0.3
0.02
0.9
0.72
1.0
0.02
0.9
0.11
0.22
0.6
0.06
0.13
Filter
0.565
BDL
BOL
BDL
BDL
BDL
BDL
BDL
0.02
BDL
BDL
BDL
O.OK
BDL
0.02
BDL
BDL
BDL
BDL
0.02
BDL
BDL
0.02
BDL
0.04
ChrytotiU
Fiberi > 106/1
RaH
1.35
0.130
1.78
3.9
0.15
0.35
0.09
0.11
0.39
0.28
0.09
0.2
oh
0.3
0.06
0.15
0.39
0.5
0.06
O.I
0.11
O.IS
0.3
0.09
0.20
Filter
0.652
1.43
B'DL
0.2
0.04
BDL
0.76
0.07
0.59
0.06
0.4
O.I
1.0
0.13
0.4
1.3
1.67
1.0
0.06
0.06
0.07
0.13
IDL
0.04
0.5

-------
added to the raw water and all three were successful for amphibole removal but
none for chrysotile.  Runs 113, 115,  117, and 118 had Catfloc B added to the raw
water and alum  and soda ash  to the second precoat step. All runs were successful
for amphibole removal but none for chrysotile.

It  is clear  that  several treatment  processes in  vacuum DE  filtration will remove
amphibole  fibers successfully  but the picture  for  chrysotile  removal  is far less
clear.  Part  of the problem may be due to  sample contamination, long storage, or
laboratory  problems.  Based  on  the  data, however, the most promising treatment
for chrysotile removal of those attempted  appears  to require  the  use of A-23 in
the second precoat step.  This would appear to  be a good  starting point in any
future research.

Table 18 shows  fiber removal data for selected ERD  (pressure) DE runs. Run 72
employed A-23  in  the second precoat  step and  alum and  soda ash in  the  body
feed and  achieved  BDL for amphibole  but was unsuccessful  for  chrysotile
removal.  Run 73 employed  Catfloc B added to the raw water and alum and soda
ash added to the second precoat step. This run  resulted in BDL for amphibole but
was  unsuccessful for chrysotile removal, Runs 78 and  79  were performed with
Catfloc  B added to the raw water and alum and soda ash added to first precoat
step. Amphibole removal  was  successfully accomplished in both runs, but neither
run achieved  satisfactory chrysotile removals.  In Runs  45, 46, 48, 49 and 51,
Catfloc  B was added to  the raw water. Amphibole removal was successful  in all
5 runs but of chrysotile  removal was successful in only  2 of  the 5 runs.

It  is evident that a  number of treatment processes in pressure DE filtration will
remove  amphibole fibers  but  successful  treatment  for chrysotile removal is less
apparent. Reasons for the  difficulties in chrysotile removal may not all be in  treat-
ment as mentioned previously, but also in collection, transporting, and processing
samples in the  laboratory. Using the available data, however,  the most  promising
treatment for chrysotile removal of those  attempted appears to require addition
of Catfloc B to the  raw water.  Addition  of alum and  soda  ash to the second
precoat step  may also be worth further  testing. Together with testing addition of
Catfloc  B to the raw water, these two processes appear to be good starting points
for future studies.

Turbidity Removal
The  effectiveness  of DE media filters  for removal  of suspended material was
clearly shown by  the results  of the pilot study. Because  vacuum DE filtration
                                     83

-------
caused problems due to dissolved gases, this treatment was not considered suitable
for treatment of Lake Superior water. Figures 26, 27, 28, and  29 show the rela-
tionship of amphibole  and chrysotile fibers vs.  effluent turbidity for both vacuum
and pressure DE  filtration.

Appendices  C-3  and  C-4  provide  data on  pressure DE filtration. Data in  these
Appendices  show that  initial runs (1-30) produced final turbidities which generally
were  below  0.5 TU but  sometimes  approached  0.8 TU. Runs 31-60  produced
lower final turbidities,generally about 0.1 TU, due to improved chemical  treatment
resulting from  the  experiences  gained   in the earlier runs.  Beginning at Run 62
and continuing to the  final Run 86, 21  runs  produced final turbidities which were
consistently below  0.1 TU.  Of the  21  runs,  8  employed  addition of Catfloc B to
the raw water, and  8  others utilized  alum and soda ash  in the body feed. All 21
used alum and soda ash in the second precoat step. It is apparent that for the  raw
water turbidity range  encountered during the pilot  plant study it is possible to
produce  consistently  a  final  water  turbidity of 0.1 TU, or  less,  with  proper
chemical treatment  and mixing.

SUMMARY OF COST ANALYSIS

Analysis of the results  presented in Section VII indicates several categories of treat-
ment  that were essentially similar in their effectiveness for removal of asbestiform
fibers and other suspended solids. These  categories were examined initially in
Section VII  considering such  parameters as  success in amphibole  fiber and mass
removal, turbidity  removal, length of  filter run, rate  of head loss buildup,  and
amount of suspended  solids in backwash water. Due to the similarity of results in
the various  categories  and in  order to  compare the two  basic types of treatment
processes, granular media  filtration and  diatomaceous earth filtration, an economic
analysis was conducted. In this manner the  cost  of treating water on a per 1,000
gallon basis could be determined for each category selected and an economic com-
parison made among all the categories.

In the economic analysis  the construction or  capital costs were based  on recent
costs  of construction  for  facilities with similar  design and operating  parameters
and  on costs  supplied by equipment  manufacturers.  A  treatment plant  with  a
nominal capacity of 30 mgd was selected for a detailed analysis utilizing the same
water supply as tested in the various pilot units. All cost  estimates were based on
December 1974  price levels. A 25 percent contingency allowance for  omissions,
engineering,  legal and administration  costs was included  in the capital costs. No
factor for inflation  was assumed.
                                      84

-------
  1.6
*>
QL
UJ
CD 1 0
Ul

o

X
Q.
2
Ld
   0.6
UJ
   0.4
   0.2
           1.
                     0.4
0.6
                                      0.8
       BDL'S
             0.2
                EFFLUENT TURBIDITY, TU
     FIGURE 26. EFFLUENT TURBIDITY VS. AMPHIBOLE
                 FIBER COUNT VACUUM DE FILTRATION.

-------
           I.IXIO*
   1.6 r
  1.4
   1.2
I
2] 1.0
OD
UJ
O
(O
>-
cc

o
o
do
  0.6
UJ
  0.2
                     1.83 X (O*
     BDL'S
f^ri
                     0.4
0.6
0.8
1.0
               EFFLUENT TURBIDITY, TU
     FIGURE 27. EFFLUENT TURBIDITY  VS. CHRYSOTILE

                FIBER COUNT VACUUM DE FILTRATION.
                         86

-------
  1.6
O


tr


iil
UJ

O
50.8
i
CL
2
<

£0.6
UJ

u.
u.
UJ
  0.4
  0.2
•fttit
 XX XXXX XX
 X X X X
 BDL'S
            0.2      04      06      08      1.0

              EFFLUENT TURBIDITY,TU
     FIGURE  28. EFFLUENT TURBIDITY VS . AMPHIBOLE
               FIBER  COUNT PRESSURE DE FILTRATION.
                       87

-------
       . 53XI06     , 9.3 XIO6
  t 6 r
  1.4
  1.2
CO
(r
ui
00 1.0
LU
  08
CE
X
o
  0.6
UJ


u.
  0.4
  0.2
    BDL
0.2      0.4      0.6      0.8

   EFFLUENT TURBIDITY, TU
                                               i.o
     FIGURE 29 .EFFLUENT TURBIDITY VS. CHRYSOTILE

                FIBER COUNT PRESSURE DE  FILTRATION.
                         88

-------
Operation and maintenance  cost  estimates were  based  on those chemical costs
actually  incurred in the  pilot plant  operation  and by  existing  water treatment
plants with similar treatment  processes as those considered. Solids produced in the
backwash process were based  on  calculated  amounts  rather  than the  lower
amounts found in samples analyzed during  the  runs, to  correct for any potential
sampling error.  An  average  flow  rate of  20 mgd  was assumed  as  the  basis for
determining operation and maintenance costs.

A  50 year economic analysis was performed on each treatment process selected
utilizing  a  discount  rate  of  5.625 per  cent as required by  the  Federal Water
Resources Council for  making economic comparisons of alternative projects. Total
first costs,  replacement costs, average annual  costs,  and  cost per 1,000 gallons of
water treated were determined.

Granular Media Filtration

Three categories of treatment were selected from the runs utilizing granular media
filtration. The  selection of these  categories had,  as a common  base, amphibole
fiber count  and mass removal to a level near or  below the detectable limits (BDL)
of the analytical equipment  and  an average effluent turbidity of 0.1 TU or less.
Economically,  the three  categories were quite attractive, with average chemical
costs of 0.35, 0.4, and 0.5 £/1000 gallons,  respectively,  as compared to  the range
of average chemical costs for all granular media runs  of 0.35  to  1.26 9/1000
gallons.

The first category, or treatment process, selected  utilized dual media filtration with
single-stage mixing as  represented by MM-1  Runs 28,  29,  30,  39, and 40 and
MM-2 Runs 50 and  53. Alum and a  nonionic polymer, 985N,  were  introduced at
average   rates of  15  and 0.05 mg/1, respectively, with  a  filter   flow rate  of
      ^9                  9
235 mj/m    day  (4.0 gpm/ftz),   producing  an  average effluent   turbidity  of
0.1 TU.  Amphibole fiber  count and mass removals were  excellent,with 4 out of 4
amphibole fiber counts  and 4 out of 4 amphibole mass removals  achieving the
above stated removal goal. The economic analysis of this treatment  process, based
on  a  30 mgd treatment  plant design, is presented in Table 19  and shows that
treated water could be produced for approximately 7.2 (j;/1000 gallons.

The second granular media filtration  category  selected  utilized  a tri-media filter
                                                               o    9
bed  with two-stage flash mixing  at a filter flow rate  of 293 irr/mz  day (5.0
      s\
gpm/ftz).  This category is  represented by MM-2  Runs 93, 94, 103,  104, and
105. Alum and a nonionic polymer, 985N,  were introduced at  average rates of 11
                                     89

-------
        TABLE 19.
             WATER TREATMENT PLANT ECONOMIC ANALYSIS - GRANULAR MEDIA FILTRATION
             30 MOD PLANT DESIGN - LAKE SUPERIOR INTAKE AT LAKEWOOD
             Process Category
                                    Dual Media Bed
                                  Q = 235 m3/m2 day
                                  Single Stage Mixing
                                Alum & Nonionic Polymer
<£>
O
Capital Costs
    First
    Replacement-present worth
     of replacement equipment
    Total-present worth of all
     capital costs, 50 year
     analysis at 5-5/8%
                                            Actual Costs
                                                                     Tri-Media Bed
                                                                  Q = 293 m3/m2 day
                                                                 Two-Stage Flash Mixing
                                                                 Alum & Nonionic Polymer
                                              5.50
                                              0.66
                                              6.16
Actual Costs
   $x!Q6

   5.25
   0.63
                                                                         5.88
                           Tri-Media Bed
                        Q = 293 m3/m2 day
                           In-Line Mixing
                      Alum & Nonionic Polymer
Actual Costs
   SxlQ6

   5.25
   0.63
                                                                                                     5.88
Average Annual Costs
First
Replacement
O&M - calculated at 20 mgd
Total
Costs per 1000 gallons
First
Replacement
O&M - calculated at 20 mgd
Total
SxlO6
0.33
0.04
0.13
0.50
6/1000 gal
4.70
0.60
1.90
7.20
SxlO6
0.32
0.04
0.12
0.48
6/lOOOgal
4.49
0.57
1.73
6.79
SxlO6
0 32
0 04
0 12
0.48
$/l OOP gal
449
0 57
1 79
6.85

-------
and 0.03 mg/1, respectively, producing an average  effluent of 0.1 TU. Amphibole
fiber count and mass removals again were excellent, with the desired removal goals
achieved for both the amphibole fiber count  and mass  removal. The  economic
analysis of this category of treatment, based on a 30 mgd treatment plant design,
is  presented in  Table 19 and  shows that treated water  could be produced  for
approximately 6.79 6/1000 gallons.

The  third  granular  media  filtration category selected  also  utilized  tri-media
filtration at a filter flow rate of 293  m3/m2 day (5.0 gpm/ft2) and is represented
by  MM-2 Runs  121, 122, and 123.  Alum and a nonionic polymer, 985N, were
introduced  through a  series  of in-line  mixers at  rates of 12  and  0.05 mg/1,
producing  an average effluent turbidity  of 0.06 TU. Amphibole fiber count and
mass  removals were excellent, with  amphibole fiber count  and amphibole mass
removal achieving the desired goal for the single test  performed. With a treatment
plant designed for 30 mgd,  treated  water could be  produced for approximately
6.85 6/1000 gallons as shown by the  economic analysis presented in Table 19.

Diatomaceous Earth Filtration

Three categories of treatment also were selected  for economic analysis from the
runs  utilizing pressure diatomaceous  earth filtration. The selection of these cate-
gories had, as a common base, amphibole fiber count and mass removal to a level
near  or below the detectable  limits  of the analytical equipment and  an average
effluent turbidity  of 0.1  TU or less. The  three categories were the  most eco-
nomically  attractive of the various categories screened, with  average chemical and
DE costs  of 2.7, 2.3,  and  2.9  6/1000  gallons, respectively, as compared to the
range  of average  chemical  costs  for  all pressure  DE runs of 2.2 to 4.5  £/1000
gallons.

The first  category selected  utilized  a medium grade DE precoat applied at 0.73
kg/m2  (0.15 lb/ft2) of filter surface area coated  with alum and soda ash at rates
of 0.11 g/g of DE and 0.055  g/g of  DE, respectively. This category is represented
by ERD-2  Runs 67, 68, and 69. A  fine grade body feed was applied at a rate of
 27.5 mg/1, with  alum at 3 mg/1 and  soda  ash at 1.5 mg/1 added to the  body feed.
 A  filter rate of 61 m3/m2 day (1.04 gpm/ft2) was utilized to produce  an effluent
 with an average turbidity of 0.06 TU.  Amphibole fiber  count and mass removal
 achieved the removal goal in 2  out  of 2 tests. The  economic analysis  of  a treat-
 ment  plant designed for  30  mgd and based  on this treatment is presented  in
 Table 20.  The analyses indicate that a treated water could be produced for 11.97
 6/1000 gallons.
                                       91

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TABLE 20.
WATER TREATMENT PLANT ECONOMIC ANALYSIS - PRESSURE DIATOMACEOUS EARTH
FILTRATION 30 MOD PLANT DESIGN - LAKE SUPERIOR INTAKE AT LAKEWOOD
       Process Category
                                   *}
                       Q = 61 rrr/mz day
                      Alum & Soda Ash to
                      Precoat and Body Feed
                        Fine Body Feed
 Q = 67 m3/m2 day
 Alum & Soda Ash to
   Precoat-Cationic
Polymer to Raw Water
   Fine Body Feed
   Q = 64 m3/m2 day
  Alum & Soda Ash to
    Precoat-Cationic
 Polymer to  Raw Water
Medium Fine Body Feed
Capital Costs
    First
    Replacement-present worth
     of replacement equipment
    Total-present worth of all
     capital costs, 50 year
     analysis at  5-5/8%
                          Actual Costs
                             $xlQ6
                              6.50
                              0.50
                              7.00
    Actual Costs
       $xlQ6
        6.10
        0.46
       6.56
     Actual Costs
        $xlQ6
         6.35
         0.49
                                                                                6.84
Average Annual Costs
First
Replacement
O&M - calculated at 20 mgd
Total
Cost per 1000 gallons
rirst
Replacement
O&M - calculated at 20 mgd
Total
$x!06
0.39
0.01
0.43
0.83
£/1000gal
5.43
0.14
6.40
11.97
SxlO6
0.37
0.01
0.39
0.77
6/1 000 gal
5.09
0.14
5.80
11.03
SxlO6
0.38
0.01
0.44
0.83
£/1000gal
5.30
0.14
6.56
12.00

-------
                                                                           ^
The second category utilized a medium grade DE precoat applied at 0.73 kg/m
(0.15  lb/ft2)   of filter surface area coated with alum and soda ash at rates of
0.11 g/g of DE and 0.055 g/g of DE, respectively. This category is represented by
ERD-2 Runs 73, 74, and  75. A  fine grade body feed was applied at a rate of
20.5 mg/1.  A cationic polymer, Catfloc B, was added to the raw water at a rate of
0.56mg/l.  A finished water with an average effluent  turbidity  of 0.06 TU  was
produced.  Amphibole fiber  count  and mass removals were excellent, achieving the
removal goal in 2 out  of 2 tests. The  economic  analysis presented in Table 20
shows that for this category a treated water could be produced for 11.03 6/1000
gallons.
                                                                            <•}
The third  category utilized  a  medium grade DE precoat applied  at 0.73 kg/m
(0.15  lb/ft2)   coated with alum  and soda ash  at rates of 0.11 g/g and 0.055 g/g
of DE, respectively.  This category is represented by  ERD-2 Runs 79, 80, and 81.
A fine grade of body feed was applied at a rate of 27.3 mg/1. A cationic polymer,
Catfloc B, was added  to  the  raw  water at  a rate  of 0.33 mg/1  to  produce a
finished  water with  an average effluent turbidity of  0.06 TU.  Amphibole fiber
count and mass removals were  excellent, achieving the removal goal in 2 out  of 2
tests. The  economic analysis.presented in Table 20 shows that for this  category
treated water  could be  produced for approximately 12.0 £/1000 gallons.

Two  other pressure  DE categories with equally  attractive chemical costs that were
examined  utilized only alum and soda ash applied to  the precoat. These categories
were  represented by ERD  Runs 59, 60,  and 62 and  ERD Runs 55,  57, and 58,
Turbidity  removal was  not  as successful, however, with average effluent turbidities
in both categories greater than 0.1 TU.

A theoretical  optimization was  performed for the  three  selected pressure DE
filtration  categories to simulate the least cost  performance for  each process and
the optimum design characteristics of the treatment  plants in  each case.   Pilot
study data from the  three  runs involved  in  each  of the three  categories  were
utilized  to predict the buildup of filter  aid density  for that category. From this
value, values for the filtration rate, terminal head loss, body feed rate, filter  area,
optimum  length  of filter  run,  and the optimum  filter operating  costs  were
 calculated. For each category, a filter flow rate of 94 m3/m2 day   (1.6 gpm/ft2)
 was  predicted as compared to 60 m3/m2  (1.0 gpm/ft2)  utilized  in the  pilot
 studies.  Body feed  rates calculated  were substantially lower than those actually
 run in the pilot studies, averaging between 5  and 10 mg/1 as compared to 20 to
 30 mg/1. Details on the DE optimization  process are provided in Appendix I.
                                      93

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The optimization resulted in lower capital and average annual operation costs for
all  three  of the selected categories. The costs in £/1000 gallons  of treated water
were optimized at 10.55, 8.50, and 8.14, respectively for  the three categories, as
compared to costs in 
-------
pressure DE filtration. The O&M costs, composed of chemical,  power, and labor
costs, constitute approximately 25 per cent of the total costs for the granular me-
dia filtration as compared to approximately 53  per cent for the pressure DE filtra-
tion. This owuld mean that increases in O&M  costs due to inflation would affect
future  costs in C/1000 gallons  for  pressure  DE  filtration more  than  granular
media  filtration.

The choice  between pressure or vacuum DE filtration and granular media filtration
would  be dependent  upon the specific application. Several factors,such as quality
of  raw water and  quantity of water  to  be treated, would have to be examined
before a  definite  selection could be made. In  the case of a treatment  plant at
Duluth designed for 30 mgd  and  utilizing  Lake  Superior water  at  the Duluth
Lakewood  Intake,  the  choice can be made based on the  economic evaluation
presented.  However, the choice of treatment plants for very small capacity instal-
lations utilizing water with different quality parameters would  require a detailed
study  of the specific conditions at each potential site.

TABLE 21.   RANGES OF  INITIAL CAPITAL  COSTS OF VARIOUS PLANT
              CAPACITIES  UTILIZING GRANULAR  MEDIA AND PRESSURE
              DE FILTRATION FOR ASBESTIFORM FIBER REMOVALa
Plant Capacity (mgd)
Process
Granular Media
Pressure DE
0.03
$x!06
0.04-0.05
0.05-0.06
1.0
$x!06
0.19-0.24
0.22-0.25
10.0
$x!06
2.9-3.4
3.1-3.5
30.0
$x!06
5.2-5.5
6.1-6.5
a Costs presented  do  not  consider replacement costs or  costs associated with pretreatment.
  Items such as existing equipment or facilities, existing distribution and storage, raw water
  quality, and site location would modify the general cost ranges presented.
 MONITORING  PLANT OPERATION
 Purpose of Monitoring

 It is customary to monitor the quality of drinking water after it is treated by a
 water  utility. This is  done for a number of reasons, including assuring both the
 consumers and  regulatory authorities that the water meet appropriate standards,
 and assuring  utility operators  and managers that the treatment plant is being
                                     95

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operated  properly and  that the  goals  of the  treatment  processes are  being
achieved.

Monitoring  techniques  vary.  The efficacy  of  clarification can be  monitored by
measuring turbidity. Waters are disinfected to kill pathogenic microorganisms, but
judgments on the achievement of this goal are made on the basis of the presence
or absence of indicator microorganisms, along with measurements of turbidity and
chlorine residual, rather than on specific tests for pathogens.

Because at the present  time there is no rapid  analytical method for detection of
asbestiform  fibers in water, treatment plant operators shall have to rely on  indi-
cators and the use of proper operational procedures to assure the  production of
water  low  in asbestiform fiber  content, just as operators now rely on indicators
for pathogens.

Effluent Turbidity

One treatment goal that  should aid in the production  of water with amphibole
fibers  present in low quantities is the attainment of an  effluent turbidity at or
below 0.1 TU. Turbidity is not a  direct measure of amphibole fiber count in
water, but  Figure 24 shows that high amphibole fiber counts were more  likely to
occur  when  effluent turbidities exceeded 0.2 TU. Filters should  be backwashed
when the effluent turbidity rises to 0.2 TU.  For chrysotile, however, there did not
appear  to be any relationship between effluent turbidity and fiber count. High
fiber  counts  occurred with both high  and  low effluent turbidities, as shown on
Figures 24  to 29. This relationship  was demonstrated for certain types of filters
and processes treating Lake Superior water.  It should not be assumed to hold true
in other parts of the country until demonstrated so by experimentation.

X-Ray Analysis for Amphibole Mass

Even  though an  effluent  turbidity goal can be stated, it is highly  desirable  that
some  monitoring capability exists, so that  an  operator  can verify that following
established  procedures  actually  does cause the reduction of asbestiform fiber
count. Ultimate proof of this now is obtained by electron microscope analysis of
water samples, a  costly and time-consuming technique. To assure that amphibole
fibers are being removed, a type of indicator test, X-ray diffraction analysis can be
performed. This  method gives results in terms of milligrams of amphibole mass
per liter of water, and it is quite useful.
                                    96

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The amphibole mass tests done at NWQL for this research were used as a guide to
planning further filtration research, because of the time delay involved in getting
back  electron microscope results. In addition, the amphibole  mass data  provided
independent verification of the ability of filters to remove amphibole fibers.

The performance of the four filtration processes as measured by amphibole mass
analysis is presented in Table 22.

TABLE 22.   SUMMARY OF NWQL RESULTS	
  Process
  Total No. Of
Samples Submitted
No. of samples with measurable
    Amphibole cone, and/or
   detection limit <0.005 mg/1
                                                                 No. of samples
                                                                 with amphibole
                                                                cone. C0.005 mg/1
Dual Media
Mixed Media
Vacuum DE
Pressure DE
32
24
29
27
24
24
21
25
22
23
17
23
 Data in this table are presented in three categories because the detection limit of
 the  X-ray  method varied,  depending in large measure on the volume  of water
 filtered. This in  turn was a function of the suspended solids content of the water,
 with higher quantities of suspended solids plugging the  membrane filter  sooner,
 resulting in higher detection limits. Thus  we  are concerned not only with how
 many samples were  submitted for X-ray analysis, but  also  with the number of
 samples to which a  definite  amphibole mass  concentration could be assigned, or
 which had an amphibole mass  concentration < 0.005 mg/1. Finally, the number of
 filtered  samples having ^0.005  mg/1 amphibole mass are tabulated.

 In  general,  each  process performed reasonably well for amphibole  removal.
 However,  the vacuum  filtration  process failed  to  achieve  10.005 mg/1 in the
 filtrate in four instances vs. one or two for the other processes.

 Amphibole Mass vs. Fiber Count - Filtered Water
 The amphibole  mass X-ray  analysis was  the principal analytical method relied
 upon for making week-to-week operating decisions during the  filtration research.
 In addition,  it has provided independent verification of the capability of filtration
 processes  to remove  amphibole fibers.  Finally, X-ray analysis  offers the  operator.
                                       97

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 of a municipal filtration plant the opportunity to monitor for amphibole removal
 at a cost much lower than electron microscope analysis.

 It can be shown statistically that X-ray analysis is useful for monitoring in place
 of electron microscope testing.  In analysis  of data from this research, a desired
 goal for amphibole fibers in filtered water was <0.04 x 106 f/1. A desired goal for
 amphibole mass was  <0.005 mg/1. One can  ask to what  extent the desired goals
 were  simultaneously  either  attained  or not attained.  If <0.04 x 10^ f/1  and
 £0.005 mg/1 generally tend to be observed together in filtered water,  then X-ray
 analysis would be a valuable tool for monitoring filter effluent.

 In order to  do  such a statistical analysis, it is necessary first to pair data from
 NWQL  and ORF.  The NWQL X-ray data had a varying detection limit,  because of
 the suspended solids  in  water filtered for  analysis. It is necessary to know if
 amphibole  mass  exceeds  0.005 mg/1,  so  for  samples  with  amphibole  mass
 expressed as  an  indefinite value below  a detection limit,   the data  could be
 considered only if the detection limit  was 0.005 mg/1 or less.  For example, a value
 expressed as 0.01 mg/1 could be greater than or less than 0.005 mg/1, so such data
 would have to be omitted in this analysis. Data are grouped according to filtration
 process, not unit, arid the only runs not included in  the statistical analysis  are
 those rejected because  of the high amphibole mass detection limit.

 The results are presented in Table 23.
TABLE 23.   COMPARISON OF AMPHIBOLE MASS AND EM RESULTS IN
              FILTERED WATER SAMPLES
                           Pairs of data         Pairs of data with simultaneous
                       amphibole mass known    occurrence of  0.04 x 106 f/1
                          to  be above or               and  0.005 mg/1 or
Process below 0.005 mg/1
Granular Dual Media
Granular Mixed Media
Pressure DE
Vacuum DE
23 -
23
24
21
<0.04 x 106 f/l and < 0.005 mg/1
20
23
18
14
Since the simultaneous  attainment of the selected values occurred in all but three
data pairs for  dual media  filtration and for every data pair  for mixed media
filtration, analysis was  made  on the basis of probability rather than by using a
                                     98

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chi-square  table. For  each process,  the hypothesis was made that  there  is no
relationship between EM and  X-ray  data. Thus the probability for simultaneous
occurrence of high  or low values  becomes  0.5, and  the significance  of the ex-
perimental results can be tested. At the 99 per cent confidence level, simultaneous
occurrences of high or low EM and X-ray values was significantly greater than one
would expect for random events for dual media, mixed media, and pressure DE
filtration. The difference was not statistically greater for vacuum DE data.

On the basis of the analysis of the probability of the observed events,  it can be
stated that for  dual and mixed media granular filtration and  for pressure DE fil-
tration,  the X-ray  amphibole mass analysis  can  be  used  to indicate if the
amphibole  fiber count of the filtered water would  be equal to  or  less than  a
count of 0.04 x 106 f/1 by ORF. Although amphibole mass should  not be used as
an indicator  for  chrysotile,  the X-ray analysis is faster  and  cheaper than EM
analysis and it  is a useful indicator method for monitoring water  for amphibole
fibers.

 Suspended Solids  Data - NWQL
 The  difference in  performance between the  vacuum  filtration process and the
 other processes can be related in part to the inability of the vacuum filter unit to
 prevent the passage  of  DE  through the  septum. In  the  suspended solids  data
 reported by NWQL, there is often a footnote beside the  BIF (vacuum DE) data
 stating that the solids were mostly DE. This judgment was based upon  visual and
 optical microscope observations.

 It can be demonstrated statistically, by comparing  mean filtered suspended solids,
 that the vacuum filtration  process  was not as effective for removing  suspended
 solids. For purposes of this comparison, data are grouped by process,  so that dual
 media filtration  includes  data from MM-1 and  MM-2.  In  order to  assess the
 capabilities of  the  processes, early  runs involving  less  successful techniques were
 excluded.  Thus in dual  media filtration  data, runs involving alum  and anionic
 polymer and all ferric chloride runs are deleted. In the mixed media  data, a run
 deliberately sampled  after turbidity  breakthrough  was deleted. All single precoat
 step runs  and  all runs involving  conditioning with  575 C polymer were deleted
 from ERD and BIF data.  The results are presented  in Table 24.
                                   99

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 TABLE 24.    SUSPENDED SOLIDS IN FILTRATE
Process
Granular Dual Media
Granular Mixed Media
Pressure DE
Vacuum DE
No. of
Samples
28
23
20
20
Mean
Suspended
Solids Standard
mg/1 Deviation
0.084 0.066
0.067 0.040
0.079 0.146
0.408 0.190
Significantly different
from BIF @ 99%
Confidence Level
Yes
Yes
Yes
—
 It is evident that the  mean suspended solids from the granular filtration and the
 pressure DE processes were  considerably lower than the solids from the vacuum
 DE  filter, and  these  differences  were statistically  significant.  This is additional
 evidence  that   the  vacuum  filtration process experienced  operating  problems
 throughout the  testing period, at  least in part because of bubble formation in the
 DE, a problem  brought about  by low water  temperatures and the  saturation of
 the raw water with dissolved  gases.

 Efforts to Develop Rapid Detection Methods

 A limited effort to learn about rapid  detection of asbestiform fibers was made in
 this research, but the  principal objective was to  learn about fiber removal by fil-
 tration. Other efforts  to develop a rapid fiber detection method are underway,
 sponsored  by EPA  and other Federal agencies.  One method being investigated
 involves placing  a water  sample  in  a  laser light  beam measuring scattered light
 from  incident  angles  of about  10°  and 135°  and relating variations  of light
 intensity and incidence  angle to the  types of particles present in water.  One  of
 the goals of these efforts is to provide a technique that is practical for monitoring
 both  amphibole  and  chrysotile asbestiform fibers  in water  at  filtration plants.
 Such  a technique should be rapid enough to permit a plant operator to make
 meaningful changes in  the treatment process in order to hold fiber content of the
 filtered water to a minimum.  Until a  more rapid method  is available, water filtra-
tion  plants on Lake Superior  should use the X-ray diffraction method, along with
occasional EM analyses.
                                      100

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FUTURE RESEARCH

Information developed in this pilot plant research permits a number of questions
to be formulated for future study. Among the ideas that could be investigated are
the following:

1.  Ways to improve chrysotile removal by anionic polymer conditioning  of DE
or  by the  use  of three-stage mixing  and combinations  of three  conditioning
chemicals in granular filtration.

2.  Effect of high algal counts on filter performance.

3.  Fiber removal during times of highest amphibole mass and fiber count.

4.  Verification of POPO optimization.

5.  Additional filtration experiments at 5 to 6 gpm/ft^ with granular filters.

6.  Effect of mixing intensity on filtration, and a comparison of back-mixing vs.
in-line mixing.
7.   Further laboratory  development,  followed  by  pilot  plant  tests,  of an
operator's method for monitoring the presence of asbestiform fibers in water.

A number of the  suggestions for future work represent an extension of past work
into  promising  study  areas.  Additional  research  is needed  to  increase  the
knowledge of the water  treatment profession  on the  topic  of asbestiform  fiber
removal by filtration.
                                     101

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                               SECTION VIII

                               REFERENCES


1.    American Public  Health Association. Standard Methods for the Examination
     of Water and Wastewater, Thirteenth Edition.  New  York, American  Public
     Health Association, 1971.  874 p.

2.    Gusmer,  J.  H.  Asbestos-Containing  Filter  Materials.  Filter  Materials,  Inc.
     (Presented at the  Joint Filtration  Symposium of the  78th National Meeting
     American Institute of Chemical Engineers. Salt  Lake City. August 19,  1974.)
     12 p.

3.    Chatfield, E. J. Quantitative  Analysis of Asbestos Minerals in Air and  Water.
     Ontario  Research  Foundation.  (Presented   at  the   32nd  Annual  Process
     Electron Microscopy Society of America. St. Louis 1974.) 2 p.

4.    Cook,  P.M.   Semi-Quantitative  Determination  of  Asbestiform  Amphibole
     Mineral  Concentrations in Western Lake Superior Water Samples.  Environ-
     mental  Protection Agency. (Presented at the 23rd Annual Denver  Conference
     on Application of X-ray Analysis. Denver. August 10,  1974.) 11 p.

5.    Cook. P.M.,  G. E. Glass, and J. H. Tucker. Asbestiform Amphibole Minerals
     Detection  and Measurement  of High  Concentrations in Municipal  Watei
     Supplies. Science.  185: pp 853-855, September, 1974.

6.    Fairless,  B.  Laboratories  That Have  Demonstrated An Ability To Analyzi
     Water Samples For Asbestiform Fibers. Environmental Protection Agency
     Chicago, 111.  Memorandum. February 24, 1975.

7.    Baumann, E. R. Diatomite Filtration of Potable Water In: Water Quality an
     Treatment, The American Water Works  Association, Inc. New York,
     Hill Book Company, 1971. p. 280-294.
                                    102

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                               SECTION IX
                               GLOSSARY

alum — aluminum sulfate
B.W. — backwash
BDL — below detectable limits
BIF —  vacuum diatomaceous earth filtration unit
cm — centimeter
m^ — cubic meter
  •3  ••}
rn^/m^ day — cubic meters per square meter day
°C - degree Centigrade
°F — degree Fahrenheit
DE — diatomaceous earth
DO —  dissolved oxygen
S/1000 gal - dollars per 1000 gallons of treated water
EPA - Environmental Protection Agency, U. S.
ERD — pressure diatomaceous earth filtration units
ERD-1  - standby ERD unit
ERD-2 - main  ERD unit
FeCl^  — ferric chloride
f/1 — fibers per liter
ft - foot
gal — gallon
gpm — gallons per minute
       ^
gpm/ftz — gallons per minute per square foot
g - gram
g/g DE —  grams per gram of diatomaceous earth
HL -  head loss
hp — horsepower
in — inch
kg - kilogram
                                  103

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kg/hr — kilograms per hour
     ^
kg/mz - kilograms per square meter
m — meter
Mm — micrometer
mph — miles per  hour
mg — milligram
mg/1 — milligrams per liter
ml — milliliter
MGD — million gallons per day
MM-1 - granular  media filtration unit designated No. 1
MM-2 - granular  media filtration unit designated No. 2
min  — minute
NWQL - National Water  Quality Laboratory
ORF - Ontario Research Foundation
Ib — pound
Ib/hr — pounds per hour
    ^
lb/ftz — pounds per square foot
psi — pounds per  square inch
lb/1000 gal - pounds per 1000 gallons
rpm  — revolutions per minute
soda ash — partly purified sodium carbonate
   9
cmz/g — square centimeters per gram
ft — square  foot
  9
m  — square  meter
SS — suspended solids
TU — turbidity unit
UMD — University of Minnesota at Duluth, School of Medicine
w/o — without
yr - year
                                      104

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                                SECTION X

                         INDEX OF APPENDICES

A-l      Weather  and Lake Level Data, Duluth  Lakewood Pumping Station,
         1974.
A-2      Raw  Water  Pumping  Schedule, Duluth  Lakewood Pumping Station,
         1974.
A-3      Raw and Effluent Water Sample Parameters, Duluth Lakewood Pumping
         Station, 1974.
A-4      Dissolved  Oxygen  Data,  Duluth Lakewood Pumping  Station Raw and
         Finished Water, 1974.
A-5      Bacteriological  Data,  Duluth  Lakewood  Pumping  Station  Raw and
         Finished Water, 1974.

B-l      Equipment Design  and Installation
B-2      Operation of Pilot  Plant Filters

C-l      Granular Media Filtration (MM-1) Summary of Individual Runs
C-2      Granular Media Filtration (MM-2) Summary of Individual Runs
C-3      Vacuum  Diatomaceous  Earth  Filtration (BIF) Summary of Individual
         Runs
C-4      Pressure  Diatomaceous  Earth Filtration (ERD)  Summary of Individual
         Runs

D-l      Granular Media Filtration (MM-1) Head Loss and Turbidity Curves
D-2      Granular Media Filtration (MM-2) Head Loss and Turbidity Curves
D-3      Vacuum  Diatomaceous  Earth Filtration (BIF) Head  Loss and Turbidity
         Curves
D-4      Pressure  Diatomaceous  Earth Filtration (ERD) Head Loss and Turbidity
         Curves

E       Ontario  Research  Foundation Electron  Microscope  Analysis Results .of
         Pilot Water  Treatment Units, Raw Water From Duluth Lakewood  Intake

F       EPA National  Water  Quality  Laboratory X-Ray  Diffraction  Analysis
          Results  of  Pilot  Water Treatment  Units,  Raw  Water  From  Duluth
          Lakewood Intake

G        University of Minnesota at Duluth Electron Microscope Analysis Results
         of Pilot  Water  Treatment Units,  Raw Water From  Duluth Lakewood
          Intake
                                    105

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H        Comparison  of  Turbidimeters, Duluth  Lakewood  Pumping  Station,
         1974.
          Diatomaceous Earth Filtration Optimization
                                  106

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
 1. REPORT NO.
     EPA-670/2-75-050a
                              2.
                                                           3. RECIPIENT'S \CCESSIOWNO.
 4. TITLE AND SUBTITLE
  DIRECT FILTRATION OF  LAKE  SUPERIOR WATER FOR
  ASBESTIFORM FIBER REMOVAL
             5. REPORT DATE
              June 1975; Issuing  Date
             6. PERFORMING ORGANIZATION CODE
 7. AUTHOR(S)
                                                           8. PERFORMING ORGANIZATION REPORT NO.
  Black § Veatch, Consulting  Engineers
9. PERFORMING ORGANIZATION NAME AND ADDRESS

  Black £ Veatch, Consulting  Engineers
  1500 Meadow Lake Parkway
  Kansas City, Missouri   64114
             10. PROGRAM ELEMENT NO.

              1CB047; ROAP 21AQB; Task  024
             11. CONTRACT/OBMflXT NO.
              DACW 37-74-C-0079
              IAG #EPA-IAG-D4-0388
 12. SPONSORING AGENCY NAME AND ADDRESS
  National Environmental Research Center
  Office of Research and Development
  U.S.  Environmental Protection  Agency
  Cincinnati,  Ohio  45268
             13. TYPE OF REPORT AND PERIOD COVERED
              Final
             14. SPONSORING AGENCY CODE
 15. SUPPLEMENTARY NOTES
  This work conducted through  interagency agreement between  EPA Region V and the Corps
  of Engineers, St. Paul District.   See also EPA-670/2-75-OSOb,  c,  d,  e, f, and g.
 16. ABSTRACT
  Pilot  plant research conducted  in  1974 at Duluth, Minnesota,  demonstrated that
  asbestiform fiber counts in  Lake Superior water could be  effectively reduced by
  municipal filtration plants.  During the study, engineering data  were also obtained
  for  making cost estimates for construction and operation  and  both granular and
  diatomaceous earth (DE) media filtration plants ranging in size from 0.03 to 30 mgd.
  Both dual and mixed-media granular filters using alum and nonionic polymer, employing
  flash  mix and flocculation without settling and DE filters with alum coated DE as
  precoat  and/or body feed or  with Catfloc B added to raw water, produced effluents
  with amphibole fiber counts  below  electron microscope detection limits.   Turbidity
  was  not  a direct measure of  fiber  count, but amphibole counts were generally lowest
  at effluent turbidities £0.1 TU.   Chrysotile removal was more difficult,  but mixed
  media  granular filtration with  alum and nonionic polymer, and DE  filtration with
  anionic  polymer conditioned  DE  frequently reduced chrysotile  fiber counts markedly.
  Systems  for economic reasons recommended for consideration during design  studies are:
  (1)  mixed media direct filtration,  5 gpm/ft2,  multiple-stage  flash mix;  (2) dual media
  filtration,  4 gpm/ft2, single stage flash mix; and (3) pressure DE filtration, 1 gpm/
  ft2, alum conditioning of precoats  and body feed, or alum conditioning of precoat
  only,  and cationic polymer fed  to  raw water.
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                              b.IDENTIFIERS/OPEN ENDED TERMS
                           c.  COS AT I Field/Group
 Asbestos
 Amphiboles
 Serpentine
 Water supply
 Filtration
 Water treatment
 Pilot plants
 Mixed media filtration
 Diatomaceous earth  fil-
   tration
 Asbestiform
 Chrysotile
 Fiber removal
 Duluth (Minnesota)
 Lake Superior
13B
18. DISTRIBUTION STATEMENT
 RELEASE TO PUBLIC
                                              19. SECURITY CLASS (This Report)
                                                   UNCLASSIFIED
                           21. NO. OF PAGES
                                 119
20. SECURITY CLASS (Thispage)
     UNCLASSIFIED
                                                                        22. PRICE
EPA Form 2220-1 (9-73)
                                             107
                                                    U. S. GOVERNMENT PRINTING OFFICE: 1975-657-59V539't Region No. 5-1 I

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