EPA-R 2-73-169
 FEBRUARY 1973             Environmental Protection Technology Series
Dewatering  of  Mine Drainage Sludge
                                    Office of Research and Monitoring

                                    U.S. Environmental Protection Agency

                                    Washington, D.C. 20460

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            RESEARCH REPORTING SERIES
Research reports of the  Office  of  Research  and
Monitoring,  Environmental Protection Agency, have
been grouped into five series.  These  five  broad
categories  were established to facilitate further
development  and  application   of   environmental
technology.   Elimination  of traditional grouping
was  consciously  planned  to  foster   technology
transfer   and  a  maximum  interface  in  related
fields.  The five series are:

   1.  Environmental Health Effects Research
   2.  Environmental Protection Technology
   3.  Ecological Research
   4.  Environmental Monitoring
   5.  Socioeconomic Environmental studies

This report has been assigned to the ENVIRONMENTAL
PROTECTION   TECHNOLOGY   series.    This   series
describes   research   performed  to  develop  and
demonstrate   instrumentation,    equipment    and
methodology  to  repair  or  prevent environmental
degradation from point and  non-point  sources  of
pollution.  This work provides the new or improved
technology  required for the control and treatment
of pollution sources to meet environmental quality
standards.

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                                                       EPA-R2-73-169
                                                       February 1973
          DEWATERING OF MINE DRAINAGE  SLUDGE

                        Phase II
                            By

                   David J.  Akers, Jr.
                     Edward A.  Moss
                    Project  14010 FJX
                     Project Officer

                    Roger  C. Wilmoth
            Environmental Protection  Agency
                    Crown  Field Site
            Rivesville, West Virginia 26588
                      Prepared for

           OFFICE OF RESEARCH AND MONITORING
         U.S.  ENVIRONMENTAL PROTECTION AGENCY
                 WASHINGTON, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402
              Price $2.10 domestic postpaid or $1.76 GPO Bookstore

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                           EPA Review Notice
This report has been reviewed by the Environmental Protection Agency and
approved for publication.  Approval does not signify that the contents
necessarily reflect the views and policies of the Environmental
Protection Agency nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
                                    ii

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                               ABSTRACT
This report is a study of various acid mine drainage sludge conditioning
methods and dewatering systems and includes an acid mine drainage and
sludge characterization program.  During this characterization program
four sludges were selected as being representative of the various types
of sludges produced by the lime/limestone neutralization of acid mine
drainage.  Three of these sludges were produced by lime neutralization
and one by limestone neutralization.

The conditioning methods studied were freezing, use of flocculants
and use of filter aids.  Freezing was studied as a method of reducing
sludge volume.  Flocculants and filter aids were studied as methods of
improving filtration rates.  Flocculants were also studied on a limited
basis as an aid to clarification.

Six dewatering systems were evaluated:

1.  Conventional Rotary Vacuum Filtration
2.  Rotary Precoat Vacuum Filtration
3.  Pressure Filtration
4.  Porous Bed Filtration
5.  Thermal Spray Drying
6.  Centrifugation

No single dewatering system was found best for all acid mine drainage
sludges.  However, on the basis of cost, the most promising acid mine
drainage sludge dewatering techniques appear to be centrifugation,
conventional rotary vacuum filtration, and rotary precoat vacuum
filtration.

This report is submitted in partial fulfillment of Grant 14010 FJX
under the sponsorship of the Environmental Protection Agency and
the Coal Research Bureau of West Virginia University.
                                  iii

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                           TABLE OF CONTENTS


SECTION                                                             PAGK

     I.  Conclusions                                                  1

    II.  Recommendations                                              3

   III.  Introduction                                                 5

    IV.  Sludge and Acid Water Characterization                       7

                 A.  Shannopin No. 1 Air Shaft Treatment Plant        7
                 B.  Banning No. 4 Treatment Plant                    8
                 C.  Norton Treatment Plant                          H
                 D.  Edgell Treatment Plant                          H
                 E.  Sampling Program                                14

                        1.  Mine Water Sampling Procedure            14
                        2.  Mine Water Chemical Analysis
                            Procedure                                14
                        3.  Mine Water Chemical Analysis Results     15

                 F.  Sludge Chemical and Physical Analyses           15

                        1.  Sludge Sampling Procedure                20
                        2.  Sludge Settling Tests                    20
                        3.  Sludge Solids Content                    20
                        4.  Sludge Chemical Analyses                 22
                        5.  Sludge Physical Analysis Results         22
                        6.  Sludge Chemical Analysis Results         26

     V.  Sludge Conditioning                                         27

                 A.  Sludge Freezing                                 27

                        1.  General                                  27
                        2.  Test Equipment - Description             28
                        3.  Test Procedure                           28
                        4.  Test Results                             28

                 B.  Conditioning for Dewatering and Clarification   35

                        1.  General                                  35
                        2.  Equipment                                36
                        3.  Filtration Procedure                     36

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                           TABLE OF CONTENTS
                              (Continued)
SECTION
                        4.  Settling Rate (Clarification)             38
                        5.  Filtration Results                       39
                        6.  Clarification Results                    39

    VI.  Sludge Dewatering                                           61

                 A.  Conventional Vacuum Filtration                  62

                        1.  General                                  62
                        2.  Test Apparatus - Description             63
                        3.  Procedure                                63
                        4.  Results                                  65

                 B.  Rotary Precoat Vacuum Filtration                70

                        1.  General                                  70
                        2.  Test Apparatus - Description             71
                        3.  Procedure                                73
                        4.  Results                                  74

                 C.  Pressure Filtration                             77

                        1.  General                                  77
                        2.  Test Apparatus - Description             77
                        3.  Procedure                                77
                        4.  Results                                  80

                 D.  Porous Bed Filtration                           86

                        1.  General                                  86
                        2.  Test Apparatus - Description             88
                        3.  Procedure                                88
                        4.  Results                                  90

                 E.  Thermal Spray Drying                            93

                        1.  General                                  93
                        2.  Test Apparatus - Description             93
                        3.  Procedure                                93
                        4.  Results                                  95
                                  VI

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                           TABLE OF CONTENTS
                              (Continued)

SECTION                                                             PAGE

                 F,  Centrifugation                                  98

                        1.  General                                  98
                        2.  Test Apparatus - Description             98
                        3.  Procedure                               100
                        4.  Results                                 101

                 G.  Summary of Results on Dewatering Attempts      102

  VII.  Economic Evaluation of Sludge Dewatering Attempts
                 A.  Conventional Vacuum Filtration                 113
                 B.  Rotary Precoat Vacuum Filtration               113
                 C.  Pressure Filtration                            114
                 D.  Porous Bed Filtration                          114
                 E.  Thermal Spray Drying                           115
                 F.  Centrifugation                                 116
                 G.  Summary                                        117

VIII.  Acknowledgments                                              123

  IX.  References                                                   125

   X.  Appendices                                                   127
                                  vii

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                                FIGURES


NO.                                                                PAGE

 1          Shannopin Treatment Plant Schematic Diagram              9

 2          Banning Treatment Plant Schematic Diagram               10

 3          Norton Treatment Plant Schematic Diagram                12

 4          Edgell Treatment Plant Schematic Diagram                ^3

 5          Settling Rate of Mixing Tank Sludge From Shannopin      23
            Treatment Plant

 6          Settling Rate of Aerator Sludge From Banning            2^
            Treatment Plant

 7          Settling Rate of Aerator Sludge From Edgell Treat-      25
            ment Plant

 8          Relationship of Freezing Time and Volume of Solids      31
            for Sludge from Shannopin Treatment Plant

 9          Relationship of Freezing Time and Volume of Solids      32
            for Sludge from Banning Treatment Plant

 10          Relationship of Freezing Time and Volume of Solids      33
            for Sludge from Norton Treatment Plant

 11          Relationship of Freezing Time and Volume of Solids      34
            for Sludge from Edgell Treatment Plant

 12          Buchner Funnel Apparatus                                37

 13          Settling Rate of Conditioned Mixing Tank Sludge         58
            from Shannopin Treatment Plant

 14          Settling Rate of Conditioned Aerator Sludge from        59
            Banning Treatment Plant

 15          Settling Rate of Conditioned Aerator Sludge from         60
            Edgell Treatment Plant

 16          Filter Leaf Apparatus                                    64

 17          Precoat Filter Leaf Apparatus                           72
                                  viii

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                                FIGURES
                              (Continued)
NO.                                                                 PAGE

18          Pressure Filtration Apparatus                           78

19          Pressure Filtration Tests of Sludge from                82
            Shannopin Treatment Plant

20          Pressure Filtration Tests of Sludge from                83
            Banning Treatment Plant

21          Pressure Filtration Tests of Sludge from Norton         84
            Treatment Plant

22          Pressure Filtration Tests of Sludge from Edgell         85
            Treatment Plant

23          Porous Bed Filtration Apparatus                         89
            (a) Top and Front View (b) Side View

24          Relationship of Drying Time and Solids Loading          92
            for Sludge from Edgell Treatment Plant

25          Spray Drying Apparatus After Bowen Engineering'  '       94

26          Centrifugation Apparatus                                99

27          Centrifugation Tests of Sludge from Shannopin
            Treatment Plant

28          Centrifugation Tests of Sludge from Banning Treat-
            raent Plant

29          Centrifugation Tests of Sludge from Norton
            Treatment Plant

30          Centrifugation Tests of Sludge from Norton
            Treatment Plant
                                  ix

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                                TABLES


NO.                                                                PAGE

 1          Shannopin Treatment Plant Chemical Analysis               ^

 2          Banning Treatment Plant Chemical Analysis                 ^

 3          Norton Treatment Plant Chemical Analysis                 18

 4          Edgell Treatment Plant Chemical Analysis                 19

 5          Sludge Sample Point Locations                            21-

 6          Summary of Results from Sludge Freezing Tests             29

 7          Effect of Flocculants  on Filtrate Increase Lime       41-48
            Sludges

 8          Effect of Filter Aids  on Filtrate Increase               49
            Norton Treatment Plant Sludge

 9          Effect of Selected Flocculants on Filtrate Increase   50,51
            Shannopin Treatment Plant Sludge

10          Effect of Selected Flocculants on Filtrate Increase   52,53
            Banning Treatment Plant Sludge

11          Effect of Selected Flocculants on Filtrate Increase   54,55
            Norton Treatment Plant Sludge

12          Effect of Selected Flocculants on Filtrate Increase   56,57
            Edgell Treatment Plant Sludge

13          Conventional Vacuum Filtration Shannopin Treatment        6^
            Plant Sludge

14          Conventional Vacuum Filtration Banning  Treatment          67
            Plant Sludge

15          Conventional Vacuum Filtration Norton Treatment          68
            Plant Sludge

16          Conventional Vacuum Filtration Edgell Treatment          69
            Plant Sludge

17          Optimum Conditions for Rotary Precoat Vacuum             76
            Filtration

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                                TABLES
                              (Continued)

NO.                                                                 PAGE

18          Pressure Filtration Tests at 5.0 pslg                     81

19          Pressure Filtration Cake Data                             87

20          Data From Drying Bed Tests                                91

21          Test Data From Spray Drying                           96,97

22          Centrifugation Tests Shannopin Treatment Plant           107
            Sludge

23          Centrifugation Tests Banning Treatment Plant Sludge      108

24          Centrifugation Tests Norton Treatment Plant Sludge       109

25          Cost Summation for Shannopin Treatment Plant             119

26          Cost Summation for Banning Treatment Plant               120

27          Cost Summation for Norton Treatment Plant                121

28          Cost Summation for Edgell Treatment Plant                122

29          Conventional Vacuum Filtration - Norton Treatment        127
            Plant Sludge

30          Rotary Precoat Vacuum Filtration - Shannopin         128,129
            Treatment Plant Sludge

31          Rotary Precoat Vacuum Filtration - Banning           130,131
            Treatment Plant Sludge

32          Rotary Precoat Vacuum Filtration - Edgell Treat-     132,133
            ment Plant Sludge

33          Pressure Filtration - Shannopin Treatment Plant      134,135
            Sludge

34          Pressure Filtration - Banning Treatment Plant        136,137
            Sludge

35          Pressure Filtration - Norton Treatment Plant         138,139
            Sludge
                                  xi

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                                TABLES
                              (Continued)

NO.                                                                PAGE

36          Pressure Filtration - Edgell Treatment Plant        140,141
            Sludge

37          Thermal Spray Drying - Shannopin Treatment Plant     142,143
            Sludge

38          Thermal Spray Drying - Banning  Treatment Plant      144,145
            Sludge

39          Thermal Spray Drying - Norton Treatment Plant       146,147
            Sludge

40          Thermal Spray Drying - Edgell Treatment Plant       148,149
            Sludge

41          Centrifugation - Shannopin Treatment Plant              15°
            Sludge

42          Centrifugation - Banning  Treatment Plant Sludge          151

43          Centrifugation - Norton Treatment Plant Sludge
                                 xii

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                               SECTION I

                              CONCLUSIONS


The major conclusions drawn from this study of four sludges produced
by the lime/limestone treatment of acid mine drainage are:

1.  The primary factors which affect the rate at which acid mine
drainage sludge can be dewatered are the solids content of the sludge
and the type of neutralizing agent used at the treatment plant.

2.  Flocculants can improve the dewaterability of the acid mine drain-
age sludges tested by as much as 74 percent.

3.  Filter aids can improve the dewaterability of the acid mine
drainage sludges tested by as much as 11 percent.

4.  It is technically feasible to dewater all sludges tested by all
dewatering systems tested except as noted below.

5.  Norton sludge, a limestone sludge, was not applicable to dewatering
by rotary precoat vacuum filtration.

6.  Conventional vacuum filtration was the least expensive method of
dewatering Norton sludge and centrifugation was the least expensive
method of dewatering Shannopin sludge.  Centrifugation and rotary precoat
vacuum filtration were the least expensive methods of dewatering Banning
sludge.

7.  Freezing acid mine drainage sludge and then thawing it signifi-
cantly reduces the settled volume of the sludge.

8.  Only systems utilizing a precoat or porous bed filtration produced
a reasonably clear filtrate.  All other systems would require recycling
the effluent to the clarifier.

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                              SECTION II

                            RECOMMENDATIONS
Additional research is needed to:

1.  Optimize the concentration of flocculants used in dewatering
systems in terms of costs rather than maximum filtration rates.

2.  Generate better data and cost figures for the dewatering systems
studied, especially conventional vacuum filtration and centrifugation,
by pilot plant studies.

3.  Optimize on a cost basis an entire treatment process including
either a conventional vacuum filtration or centrifugation dewatering
system.

4.  Improve the efficiency of porous bed filtration by optimizing
depth of bed flooding and studying methods such as the use of floc-
culants and filter aids to increase the rate of drying of the sludge.

5.  Determine the optimum operating parameters and the costs of freezing
acid mine drainage sludge.

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                              SECTION III

                             INTRODUCTION
This is the final report on Environmental Protection Agency Grant
14010 FJX'entitled "The Thickening and Dewatering of Precipitates
from the Lime/Limestone Treatment of Mine Drainage."  Work on this
program was conducted at the Coal Research Bureau, School of Mines,
West Virginia University.

One product of the neutralization of acid mine drainage by either
lime or limestone is a precipitate (sludge) of less than 10 percent
solids.  Currently, this waste product is either permanently impounded
in large earthen lagoons or pumped into mined out underground workings
or abandoned surface mines.

In situations where underground disposal is not practical, the permanent
impoundment of3 this precipitate is proving to be costly in view of
rising land values.  Also permanent impoundment requires the construc-
tion of large earthen lagoons which may be expensive to build, mar the
landscape, create a potential hazard when abandoned and represent a very
inefficient use of land. ,

The purpose of this project was to evaluate a number of methods of de-
watering this precipitate in order to reduce the problem of its disposal.
After studying methods used in the United States and abroad to dewater
other sludges such as the sludge produced by pickle liquor neutraliza-
tion and sewage sludge, a series of dewatering systems was selected.
Each system was studied individually (generally by using bench scale
equipment) as to the feasibility of its application in the dewatering
of coal mine drainage sludge.  All the systems were then compared on
the basis of cost and overall efficiency.

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                              SECTION IV

                SLUDGE AND ACID WATER CHARACTERIZATION
Before a study of the dewatering and conditioning characteristics of
various coal mine drainage sludges could begin it was necessary to
select a few sludges which would be representative of the range of
sludge types commonly produced.  Therefore field trips were taken to
a number of treatment plants utilizing either limestone or lime
neutralizing agents.

It was found that two factors affected the type of sludge that was pro-
duced from the treatment process.  The first factor was the type of
acid water being treated.  Four types of coal mine waters xrore of
interest.  The first was an acid discharge, characterized by a low pH,
high acidity and high mineral content (the mineral content as used
in this report refers to the minerals in solution).  The second vmter
represented mine drainages with a pH of abotit 5.0 with most of the iron
in the ferrous state.  The third type of water represented mine x
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operated in the Pittsburgh bituminous coal seam using continuous mining
methods.  The acid water treated was of the type which had a low pH,
high acidity and high mineral content.

The Shannopin Mine No. 1 Air Shaft Treatment Plant treated 700,000
gallons per day (gpd) of acid water and consumed 5 to 6 tons of quick-
lime per day.  A schematic diagram of this treatment plant is presented in
Figure 1.

Acid water was pumped from the mine into a 3,500,000 gallon holding
pond that had a retention time of five days.  Part of the acid water
flowed by gravity to a slake tank where it was mixed with quicklime which
was also fed by gravity using a screw feeder.  The slaked lime was mixed
with acid water in a small mixing tank creating a lime slurry that had
a pH of between 11 and 12.  The lime slurry flowed from the mixing tank
into a sluiceway.  Approximately 20 feet along the sluiceway, after
leaving the mixing tank, two pipes added more mine water from the holding
pond to the lime slurry lowering the pH to approximately 8.5.  Since
the sluiceway was about 200 yards long the lime slurry and mine water
were extensively mixed and further aerated as they flowed toward the
settling pond.

When the plant was first constructed, a surface aerator was used, but
it was found that sufficient ferrous oxidation occurred in the holding
pond to make further aeration unnecessary.  After mixing, the slurry
flowed into one of two large settling lagoons (30,000,000 gallon capac-
ity and 72,000,000 gallon capacity).  When one settling lagoon was
being used, the other lagoon was drained of as much water as possible
and the sludge allowed to dry and compact.  The two lagoons were alter-
nated in this manner and the sludgy permanently impounded in these
lagoons.
                     Banning No. 4 Treatment Plant

Banning Treatment Plant treated water from the Banning No. 4 Mine which
worked the Pittsburgh seam using continuous mining methods.  The acid
water treated was fairly representative of the type with a pH of around
5.0 and most of the iron in the ferrous state.  The pH of this water
was, however, found to be lower than 5.0, averaging around 3.1.  This
plant operated on a four day per week, twenty-four hour per day schedule
and treated 2,200 gpm of acid water using hydrated lime at the'rate of
one-half  ton per hour.  Figure 2 is a diagram of this treatment plant.

Banning started its operation by mixing treated water with hydrated lime
to form a two percent lime slurry.  Mine water was pumped directly from
the mine sump to the aerator tank where it was combined with the lime
slurry.  A pH probe located in the aerator t?ank regulated the flow of

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          3,500,000
          GALLON
          HOLDING
          LAGOON
                                                           30,000,000 GALLON
                                                           SETTLING  LAGOON
                                                    (UNDERGOING COMPACTION AT PRESENT)
                                  QUICKLIME
                                  STORAGE
                                  BIN
                                                            STEEL
                                                            SLUICEWAY
                                     SLURRY
                                     TANK
                                                              72,000,000 GALLON
                                                              SETTLING LAGOON
UNDERGROUND
PUMP
                                                                               EFFLUENT
                                                                               TO STREAM
Figure I-SHANNOPIN TREATMENT PLANT SCHEMATIC  DIAGRAM.

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                                                                HYDRATED
                                                                LIME
                                                                STORAGE
                                                                BIN
 SLUDGE TO
 WASTE DUMP
                       EFFLUENT TO SLURRY MIXING TANK
       EFFLUENT
       TO STREAM*
                                                            SLURRY
                                                            MIXING
                                                            TANK
                            104 FT.  DIAMETER
                          CLARIFIER WITH  RAKE
SURFACE
AERATORS

	
1— — —



1^ 	 ^J
SLOW
MIX
TANK
                                                                      UNDERG
                                                                      PUMP
Figure 2- BANNING TREATMENT PLANT SCHEMATIC DIAGRAM.

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lime slurry to maintain a treatment pH of approximately 8.5.  Two
floating aerators mixed the acid water and lime slurry while aerating
the mixture.  After 30 minutes retention time in the aeration tank, the
slurry flowed to a slow mix tank and then into a 104 foot diameter
thickener clarifier.  The settled sludge was moved to the center of the
thickener by a rake mechanism.  The sludge was then pumped for permanent
storage into a settling basin that was also being used to store coal
refuse.  Part of the settled sludge (30-40 percent) was recirculated to
the aeration tank.
                        Norton Treatment Plant

Acid water treated at Norton was pumped from the Grassy Run stream which
was heavily polluted from abandoned coal mines.  The water from this
stream was highly acidic (pH 2.8) with nearly all of the iron in the
water in the ferric state.  This treatment plant, operated by the
Environmental Protection Agency, was used for experimental purposes
only.  A diagram of the treatment plant is presented as Figure 3.

The acid water was pumped from Grassy Run through a sand filter into a
500 gallon holding tank.  From the holding tank the acid water was then
pumped at the rate of 15 gallons per minute into two 150 gallon mixing
tanks where the water was mixed with limestone rock dust.  The limestone
addition was regulated by a pH recorder which maintains a pH range within
the mix tank of 4.9 to 5.1.  The treated water from each mix tank was
then pumped into its individual 11,700 gallon settling tank.  Total re-
tention time for this system was approximately 14 hours.  The treated
effluent was then drawn off the settling tank and flowed back into the
Grassy Run stream.  Sludge was pumped off the bottom of the settling
tanks into a 11,700 gallon sludge holding basin for further dewatering.
Final sludge disposal was accomplished by dumping the sludge into mined
out workings for perpetual storage.
                        Edgell Treatment Plant

Mine water at  the Edgell Treatment Plant was pumped directly from a
sump located at the western end of the Williams Mine.  The Williams
Mine was being operated by continuous mining methods and was mining part
of the Pittsburgh coal seam.  The acid water was of the type which was
nearly neutral and contained iron primarily in the ferrous state.  Part
of the untreated mine water was used to mix the slurry in the slurry mix
tank (lime consumption 480 pounds/hour) and the remainder of the mine
water was directed into the flash mixer for complete neutralization (see
Figure 4).  The treatment pH for this operation was 8.0 to 8.4.  The
neutralized water then flowed by gravity into an earthen aerating lagoon
that had a 15  hp surface aerator.  The aerating lagoon had two outlets
which allowed  the sludge and treated water to flow by gravity into
                                  11

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EFFLUENT
   *
TO STREAM
               11,700 GALLON
               SETTLING TANK
11,700 GALLON
SETTLING TANK
                         LIMESTONE
                         STORAGE
                         BINS
                          ISO GALLON
                          MIXING TANKS
                                                                             11,700  GALLON
                                                                             SLUDGE HOLDING
                                                                             BASIN
                              EFFLUENT
                              TO STREAM
SLUDGE
TRUCKED
AWAY
                                                                                         MINE WATER
                                                                                         FROM STREAM
                                 SAND
                                 FILTER
                                                                                            £3
                                                                              500  GALLON
                                                                              HOLDING TANK
        Figure 3- NORTON  TREATMENT  PLANT  SCHEMATIC DIAGRAM

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              HYDRATED
              LIME
              STORAGE
              BIN
              SLURRY
              MIXING fe
              TANK
                                        SURFACE
                                        AERATOR
                                                         EARTHEN SLUICEWAYS/
                                                55,000,000
                                                GALLON
                                                SETTLING
                                                LAGOON
• ^^^^^B I
Q
UNDERGROUND
PUMP
EFFLUENT
TO STREAM
 Figure 4-EDGELL TREATMENT PLANT  SCHEMATIC DIAGRAM.

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separate ends of the settling pond.  The settling pond had a capacity
of 55,000,000 gallons and was used to perpetually store the sludge.
The Edgell Plant treated mine water at the rate of 1,000 gallons per
minute and ran on a twenty-four hour per day, seven day per week
schedule.

                           Sampling Program

A sludge and acid water sampling and analysis program was conducted at
each of the four characteristic treatment plants between June 22, 1970
and November 24, 1971.  The purpose of this program was to provide
information as to the variability of acid water and sludge at each
treatment site and to collect sludge for the dewatering investigations.
Since the primary purpose of this study was concerned with dewatering,
no attempt was made to collect samples from the treatment sites at
regular intervals, but rather samples were taken when additional sludge
was needed for the dewatering studies.

Mine Water Sampling Procedure

Mine drainage chemical composition, especially the ferrous to ferric
iron ratio, was very unstable and began to change upon formation.  The
main difficulty encountered in the sampling of mine drainage was keeping
the iron constituents ratio stable long enough for the sample to be
transported to the laboratory for analysis.

In order to completely determine the concentrations of the ferrous iron
present in mine drainage, the following sampling and analytical procedure
was devised.  A mine water sample was taken at the point of treatment
and was placed in a polyethylene bottle.  The bottle was filled to its
top to exclude as much air as possible.  A second mine water sample was
filtered through Whatman No. 40 filter paper into a polyethylene bottle
that contained 100 milliliters (mis) of 3 normal hydrochloric acid.
A third sample of mine water was placed into a polyethylene bottle
that contained 20 mis of an acid mix of equal parts of sulfuric and
phosphoric acid.  All three mine water samples were returned to the
laboratory for immediate analysis.

Mine Water Chemical Analysis Procedure

Mine water was analyzed for total iron, ferric iron, ferrous iron,
silicon, aluminum, magnesium, calcium, acidity, alkalinity and sul-
fates in order to determine the major chemical parameters of the water.
The chemical analysis was initiated in the field by determing the pH
using a portable battery operated pH meter.  The remaining analyses
were performed in the laboratory.

The first water sample was immediately analyzed for acidity and alka-
linity.   Acidity analyses were performed by the Salotto Method.

                                  14

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Alkalinity determinations were made using the method subscribed to by
the American Water Works Association.(2)  This latter method of analysis
was used to determine the carbonate, bicarbonate and hydroxide alkalin-
ity properties, and enabled the calculation of total alkalinity based
on these results.

The second mine water sample had been filtered to remove all the precipi-
tated ferric hydroxide in the raw water.  The 3N hydrochloric acid added
to the sample minimized further iron oxidation and precipitation.  The
sample was analyzed for silicon, aluminum, magnesium, calcium and total
iron using a Perkin-Elmer Model 303 Atomic Absorption Spectrometer
equipped with a DCR-1 digital readout device.  Sulfates were analyzed
using the barium chloride gravimetric method.

The third mine water sample which had been acidified with tfye sulfuric-
phosphoric acid mixture was analyzed for ferrous iron by the potassium
dichromate method described by Hall.(3)

The ferric iron was determined by subtracting the ferrous iron result
from total iron as determined by atomic absorption.
 Mine Water Chemical Analysis Results

 Shannopin acid water was  the most highly mineralized of the four waters
 studied as shown in Tables  1 through 4.  Norton acid water was the
 lowest in mineral content.  The Shannopin acid water was particularly
 high in aluminum and total  iron relative to the other three waters.
 The Shannopin water, however, was relatively low in ferrous iron content
 presumably due to aeration  or bacterial oxidation occurring within the
 holding pond.  The Norton acid water was by far the lowest in ferrous
 iron as it was collected  from a stream and was well aerated by natural
 processes.

 No carbonate or  hydroxide alkalinity was found in any of the samples;
 however, bicarbonate was  detected in some Edgell samples.

 The four acid waters studied represented a wide range of chemical compo-
 sition and should therefore be reasonably representative of the range
 of mine drainage normally encountered.  Mine water types of such quality
 as to not require treatment were not included in this survey
                 Sludge Chemical and Physical Analyses

 The  following  information was determined in order to define the major
 physical and chemical parameters of the sludges.

 1.   Settling rate of slurries.
 2.   Percent solids of slurries and settled sludge.

                                  15

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                               Table 1



             Shannopin Treatment Plant Chemical Analysis




                       Analysis of Raw Water

PH
Ca (ppm)
Mg (ppm)
Al (ppm)
Si (ppm)
SOf (ppm)
Fe4"4" (ppm)
Fe44* (ppm)
Total Fe (ppm)
Acidity (ppm CaC03)
HCO* (ppm CaC03)
Analysis

Ca (ppm)
Mg (ppm)
Al (ppm)
Si (ppm)
S0« (ppm)
Total Fe (ppm)
Nonfilterable Solids (ppm)
High
2.9
430
200
150
40
5,000
180
500
670
2,400
0
of Slurry
High
2,100
200
150
60
5,000
640
39,300
Low
2.7
400
150
120
30
4,300
10
430
510
1,800
0

Low
1,400
180
130
0
4,400
470
3,800
Mean
2.8*
410
170
140
35
4,500
100
480
580
2,000
• 0

Mean
1,600
190
140
40
4,600
550
14,300
Median Value
16

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                               Table 2



              Banning Treatment Plant Chemical Analysis



                       Analysis of Raw Water

pH
Ca (ppm)
Mg (ppm)
Al (ppm)
Si (ppm)
SO^ (ppm)
Fe44 (ppm)
Fe444 (ppm)
Total Fe (ppm)
Acidity (ppm Ca(X>3)
HCO- (ppm CaC03)


Ca (ppm)
Mg (ppm)
Al (ppm)
Si (ppm)
SO? (ppm)
Total Fe (ppm)
Nonfilterable Solids
High
3.3
490
140
40
30
2,900
180
90
260
850
0
Analysis of Slurry
High
950
130
50
25
2,800
300
(ppm) 3,400
Low
2.8
420
120
25
20
2,400
140
50
200
530
0

Low
770
120
40
25
2,700
210
1,400
Mean
3.1*
450
130
35
20
2,700
160
60
220
680
0

Mean
860
130
45
25
2,700
260
2,400
Median Value
17

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                               Table 3



             Norton Treatment Plant Chemical Analysis



                      Analysis of Raw Water

PH
Ca (ppm)
Mg (ppm)
Al (ppm)
Si (ppm)
SOg (ppm)
Fe"*"1" (ppm)
Fe*1*"1" (ppm)
Total Fe (ppm)
Acidity (ppm CaC03)
HCO* (ppm CaC03)


Ca (ppm)
Mg (ppm)
Al (ppm)
Si (ppm)
SOjj (ppm)
Total Fe (ppra)
Nonfilterable Solids
High
2.9
160
35
40
20
1,000
3
120
120
670
0
Analysis of Slurry
High
500
35
35
15
1,100
120
(ppm) 250
Low
2.8
100
25
20
10
600
1
55
60
360
0

Low
180
25
20
7
610
50
45
Mean
2.9*
120
30
30
10
800
2
90
90
520
0

Mean
310
30
25
10
790
90
140
Median Value
18

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Edgell


pH
Ca (ppm)
Mg (ppm)
Al (ppm)
Si (ppm)
S0« (ppm)
Pe4"*" ppm
Pe44* ppm
Total Fe (ppm)
Acidity (ppm CaC03)
HCO- (ppm CaC03)


Ca (ppm)
Mg (ppm)
Al (ppm)
Si (ppra)
SO^ (ppm)
Total Fe (ppm)
Nonfilterable Solids
Table 4
Treatment Plant Chemical
Analysis of Raw Water
High
6.7
480
150
50
25
5,900
870
80
870
1, 700
440
Analysis of Slurry
High
1,400
80
75
20
4,300
340
(ppm) 3,100

Analysis

Low
4.6
280
75
2
5
4,100
210
0
220
50
0

Low
620
70
8
9
4,200
220
760



Mean
6.0*
370
95
20
15
4,800
460
30
490
660
110

Mean
920
75
35
15
4,200
260
2,200
Median Value
19

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3.  Chemical composition of slurries.
Sludge Sampling Procedure

Two types of sludge were taken during the sludge sampling and analysis
program.  The first sample was the sludge slurry that was formed by the
neutralization process.  This sample reflected the characteristics of
the treatment plant at the time of sampling.  These samples were taken
prior to discharge in the settling lagoon.  Settled sludge was the second
sample taken and it was used in the evaluation of the various dewatering
apparatus examined.  In all cases, except for the Banning Treatment Plant,
settled sludge was pumped from the bottom of the settling lagoon near
the slurry discharge point in order to get as fresh a sample as possible.
Settled sludge samples from the Banning Treatment Plant were taken from
a bleeder line off the sludge recirculation system located in the main
treatment plant building.  All sludge samples were brought back to the
laboratory in five gallon plastic jugs or 55 gallon drums.

The sludge sampling points for each treatment plant are summarized in
Table 5.
 Sludge Settling Tests

 Settling  tests were conducted in the field using 1,000 ml volumetric
 flasks, 1,000 ml graduated cylinders, and a timer.  A settling test
 was  initiated by filling a volumetric flask with slurry and immediately
 transferring the slurry to the graduated cylinder.  The initial height
 of the slurry and starting time were recorded.  As the sludge settled
 in the graduated cylinder, periodic readings of the sludge interface
 were taken and the data plotted.

 Settling  tests performed in the field were conducted to determine the
 sludge settling rate for the first few hours.  Additional samples were
 brought back to the laboratory in order to determine the final settled
 volume.   The rate of settling was also recorded for the samples re-
 turned to the laboratory in order to determine the effect of previous
 settling  on the settling rate.
Sludge Solids Content

Percent solids determinations were performed routinely on the slurry
and the settled sludge.  The methods of analyses used for determination
of percent solids of slurry and settled sludge (nonfilterable) were
essentially the same as the procedures described in the Federal Water
Pollution Control Administration Manual.(4)

                                  20

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                                             Table 5

                                  Sludge Sample Point  Locations


    Type of Sludge        Banning Plant        Edgell  Plant      Norton Plant        Shannopin Plant
to
M
    Slurry              At slow mix tank       At discharge      At discharge       At discharge point
                                               point from       points into        in lagoon
                                               aerator          settling  tank


    Settled sludge      From bleeder line      Off shore  of      From settling      Off shore of
                        located in treat--      settling         tank               settling lagoon
                        ment plant             lagoon

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 Sludge  Chemical Analyses

 Chemical  analyses were performed on  the slurry sludge.  The purpose
 of  the  chemical analyses was  to observe the change in sludge chemical
 constituents  as the raw water changed.  Iron, calcium, magnesium,
 aluminum,  silicon and sulfates were  routinely determined for all  the
 sludge  samples.  Atomic absorption analysis was used for the determin-
 ation of  metallic ions after  dry precipitates present in the sample
 were dissolved with hydrochloric acid.  Sulfates were determined  by  the
 barium  chloride gravimetric method.  Tables 1 through 4 summarize the
 chemical  data for each slurry*
 Sludge Physical Analysis Results

 Sludge treated at  the Edgell Treatment Plant settled faster  than  the
 other two  lime sludges examined; the next fastest being Banning sludge
 followed by  the Shannopin sludge.  Norton sludge did not settle with
 a distinguishable  interface and so its rate of settling was  not eval-
 uated.  From the settling tests conducted it can be concluded that
 most of the  settling for each sludge was complete in three hours  or
 less.  The settling rates for the three sludges which settled with
 a distinct interface are shown in Figures 5 through 7.  These figures
 also show  a  comparison between the settling rate for each sludge
 upon collection and its settling rate approximately 24 hours later
 when the sample was resettled in the laboratory.

 Each sludge  occupied a different volume after settling and compaction
 were complete.The  Norton sludge settled to the lowest settled volume
 (1.1 percent).  The Edgell sludge settled to the next higher volume,
 (4.0 percent) followed by Banning (8.0 percent) and then Shannopin,
 (25.0 percent).  All sludge volumes are given in terms of percent of the
 original slurry volume.

 The  general  settling properties of the sludges studied are similar to
 other mine drainage sludges reported in the literature.  The limestone
 sludge settles to a very small volume which agrees with previous work
 conducted by Wilmoth et al.W; however, since the Norton water was
 the  lowest in mineral content of those studied, its relatively smaller
 sludge volume cannot be attributed only to the use of limestone but also
 to the small amount of sludge forming minerals in the water.  In the
 report by Wilmoth et al.  a direct comparison was made between lime and
 limestone sludge.  Norton sludge (the limestone sludge) was found
 to occupy only two thirds of the volume of the lime sludge.  Similarly
 the Shannopin sludge,  which is created from a highly mineralized mine
water neutralized with quicklime,  had a large final settled volume.  As
would be expected,  sludge from Shannopin and Banning settled faster in
the laboratory than in the field since any surface change on the labor-


                                  22

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          100
ro
           GO
     SETTLED

      SOLIDS-
     % VOLUME
           40
                     10
20       30       40       50
    SETTLING TIME - MINUTES
60
     Figure 5-SETTLING RATE OF MIXING TANK SLUDGE FROM  SHANNOPIN  TREATMENT PLANT

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     too
     80
     60
SETTLED

 SOLIDS-

% VOLUME
     40
     20
       0       10      20       30      40       50       60
                             SETTLING  TIME-MINUTES

      6- SETTLING RATE OF AERATOR  SLUDGE FROM BANNING TREATMENT PLANT.

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          100
N)
in
          80
      60
SETTLED
 SOLIDS-
%VOLUME
      40
           20
            "0        10      20       30       40       50       60
                                     SETTLING TIME-MINUTES
    Figure 7- SETTLING  RATE OF AERATOR SLUDGE FROM EDGELL TREATMENT PLANT.

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atory sample had been dissipated by previous settling.  Edgell sludge
showed little change in settling rates after previous settling, indica-
ting that settling had little effect on the physical character of the
sludge particles.
Sludge Chemical Analysis Results

The results of the sludge characterization program are summarized in
Tables 1 through 4.  The Shannopin slurry was the highest in elemental
concentrations of the four sludges studied and also was highest in
nonfilterable solids.  This was to be expected since Shannopin water
had the highest mineral content of the four waters.  The Norton slurry
was the lox^est in elemental concentrations and again this is to be
expected since Norton water x?as the lowest of the four in mineral con-
tent.

The four slurries represented a fairly wide range of chemical composition
and should therefore represent a fair cross section of the various
types of sludges.
                                 26

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                               SECTION V

                          SLUDGE CONDITIONING
Several sludge conditioning methods were examined in order to re-
duce sludge volume and/or increase filtration rates during sludge
dewatering processes.  A unique conditioning process called sludge
freezing was investigated as a method of reducing sludge volume and
numerous flocculants and filter aids were investigated as conditioning
agents to increase filtration rates.  Since the purpose'of this report
was primarily to determine the feasibility and efficiency of various
coal mine drainage sludge dewatering systems, flocculants were
evaluated primarily as they related to dewatering.  However, it was
reasoned that if a flocculant was to be utilized at a treatment site
for dewatering, it could be applied to the slurry before it entered
the clarifier and simultaneously enhance both settling rates and
dewaterability.  Accordingly, clarification studies were also conducted
on various sludges using flocculants which were selected with improved
filtration rates as a criteria.
                            Sludge Freezing
General

Freezing, as a sludge conditioning process, has been investigated by
a number of researchers with sewage and water works sludges.  Early
investigations found that, after freezing, sludge solids settled at
a faster rate and settled to a smaller volume than did unfrozen
sludge solids.  The nature of the freezing process is not exactly known;
however, freezing appears to destroy the gelatinous structure of the
sludge allowing the entrapped water and solids to separate.

The early research into sludge freezing has resulted in the construc-
tion of several plants that freeze conditioned waterworks sludge.  Due
to the relatively high cost per unit volume of freezing, secondary
sludge thickening was especially attractive and is generally utilized
at these plants.  The designers found, for example, in one plant that
by slow stirring, the quantity of sludge to be frozen could be reduced
from 33,000 gpd at .5 percent solids to 6900 gpd at 2.4 percent solids.
Following the thickening process the sludge was pumped to a freezing
tank where it was frozen and then thawed.  The sludge solids and liquid
were then allowed to separate by gravity draining.^

From the early research it was found that sludge must be completely
frozen but at a relatively slow rate.(?)  Recent studies on sewage
sludge have shown that sludge freezing can be achieved by using the
film-freezing principle.  Film freezing of sludge operates on prin-
ciples similar to extended freezing but freezing time is reduced since ,
the sludge is frozen as a thin film.^
                                   27

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The cost of freezing waterworks sludge was found to be high.  In one
case, the freezing cost was $6.78 per 1000 gallons of sludge as compared
to $5.04 per 1000 gallons of sludge dumped into lagoons.  One of the
major justifications of the extra cost was the use of the land for
agricultural purposes that would have otherwise been used for la-
goons
Test Equipment - Description

To observe the effects of freezing on different types of coal mine
drainage sludge, laboratory scale freezing tests were conducted on the
four characteristic sludges.

Equipment used for this series of experiments consisted of a conven-
tional freezing compartment of a household refrigerator, plastic
beakers, graduated cylinders, a thermometer, and a timing device.
Test Procedure

In order to observe the general effects of freezing on sludge proper-
ties, a standard was established for comparison.  This was accomplished
by taking 500 ml samples of the 4 sludges described in the sludge and
acid water characterization section, allowing each to settle for
six hours, and determining the final settled volume of the sludge.
Following the establishment of a standard unfrozen settled volume for
each sludge, 500 ml samples of the four sludges were then introduced
into a freezing environment (-14°C) for 4, 5, 6, 7, 8, and 24 hours.
After freezing, each sample was allowed to thaw and then was reintro-
duced into a 500 ml graduated cylinder.  The sludge was allowed to
settle for six hours and the final settled volume was determined along
with percent solids of the settled sludge.
Test Results

Artificial freezing was found to reduce the volume of coal mine drain-
age sludge.  Table 6 summarizes the results from the sludge freezing
experiments.

Freezing appeared to have the greatest effect on the sludges that were
produced from lime treatment.  This was evidenced by the similarity in
the reduction of settled sludge volume (approximately 90 percent)
following freezing from the Shannopin, Banning and Edgell sludges.
These plants used either hydrated lime or slaked quicklime for water
treatment.  However, in the case of the Norton sludge which was
                                  28

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                                Table 6

             Summary of Results from Sludge Freezing Tests
Treatment Plant

  Norton

  Edgell

  Banning

  Shannopin
  Sludge Solids Content
After Freezing (percent)*

          21.0

          17.8

           6.3

          13.9
       Reduction in
  Settled Sludge Volume
After Freezing (percent)**

         47.0

         90.6

         90.5

         88.5
   6 hours of settling and water over sludge removed
 **
   6 hours of settling
                                  29

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treated with limestone, a reduction in settled volume of only 47.0
percent was observed.

The reasons for the substantially greater decrease in settled sludge
volume after freezing for lime sludges compared to the limestone sludge
are not exactly known.  However, it is known that the sludges created
from lime treatment are substantially more gelatinous in structure and
hold more water than sludges from limestone treatment.  Since the effect
of freezing is thought to be due to a breaking down of the gelatinous
structure of the sludge, a greater degree of volume reduction following
freezing would be expected with lime sludges.

                                           •,
Figures 8, 9, 10 and 11 illustrate the relationship of degree of
freezing to settled sludge volume.  It can be seen from the graphs that
as the time the sludge was in the freezing environment increased, the
settled volume of the sludge generally decreased.

The graphs, to a certain degree, suggest a near linear relationship
between the degree of freezing and final settled sludge volume at least
for the first portion of the curves.

The time necessary to completely freeze the quantities of sludge that
were studied is undoubtedly less than 24 hours.  It was the intention,
however, to guarantee complete sludge freezing, therefore, an arbitrary
24 hour maximum freezing time period was chosen.

It can be concluded from the graphs that the full effects of freezing
do not take place until the sludge is completely frozen.  This fact
agrees with research conducted on other types of sludge.(9)

Accompanying the substantial reduction in sludge settled volume fol-
lowing freezing was the requisite increase in sludge percent solids as
shown in Table 6.  The final percent solids of the frozen sludge was
determined following six hours of settling with the clarified water
over the top of the sludge removed.

To summarize, artificial freezing of coal mine drainage sludge can
in most cases substantially reduce the final settled volume and con-
currently increase the sludge solids content.  The research conducted
on freezing of coal mine drainage sludge suggests that the success
achieved with a commercial waterworks sludge freezing process could
be emulated with coal mine drainage sludge.  The ultimate application
will, of course, relate to the economics of the process.
                                  30

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     100
      80
      60
SETTLED
SOL IDS-

% VOLUME
      40
      20
                                 345
                                 FREEZING TIME - HOURS
8
Figure 8-RELATIONSHIP OF  FREEZING  TIME AND VOLUME  OF SOLIDS FOR SLUDGE FROM SHANNOPIN
       TREATMENT PLANT

-------
      100
       80
       60
 SETTLED
  SOLIDS-
 %VOLUME
       40
OJ
       20
        012345
                                  FREEZING TIME-HOURS

 Figure 9-RELATIONSHIP OF FREEZING TIME AND VOLUME OF SOLIDS FOR SLUDGE  FROM  BANNING
        TREATMENT PLANT.

-------
      80
      60
 SETTLED

 SOLIDS-

 %VOLUME
      40
U)
      20
                 I
       ^


 24 Hours \ >
8
                                                                                 1/tr
                         234567
                                  FREEZING TIME - HOURS
Figure 10-RELATIONSHIP  OF  FREEZING TIME  AND VOLUME OF SOLIDS FOR SLUDGE FROM NORTON
        TREATMENT PLANT.

-------
     100
      60
SETTLED

SOLIDS

%VOLUME
      40
      20
                                 345
                                 FREEZING TIME-HOURS
6
 Figured- RELATIONSHIP OF FREEZING TIME AND VOLUME OF SOLIDS  FOR SLUDGE FROM
         EDGELL  lf*EATMENT  PLANT.

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               Conditioning For Dewatering and Clarification

General

Chemical conditioning (the use of chemicals to alter sludge character-
istics) of sewage and industrial sludges has been studied by various
workers and found to be a reasonably successful method of improving
solid-liquid separation.  This success prompted the investigation
of chemical conditioning of coal mine drainage sludge.

After a thorough search of the technical literature, it was concluded
that chamical conditioning with flocculants and filter aids might be
promising.  Flocculants are generally high molecular weight, water
soluble synthetic polymers that improve solid-liquid separation by a
combination of several mechanisms such as surface charge reduction
and absorption.

Charge reduction or neutralization occurs when electrical charges on
the surface of the solid particles are reduced.  The solid particles
are then no longer repellent and can adhere or coagulate when they
come in contact with each other.

Absorption is achieved when the polymer molecules attract and hold
particulate matter.  The polymers may also attach to each other in
a bridging action which can result in the formation of clumps of
particles many times larger than the original particles.

The result of charge reduction and absorption is flocculation which
produces heavier, faster settling particles thereby improving
solids-liquid separation.

Filter aids are chemicals which increase the permeability of a
filter cake (a relatively compact sludge layer on a dewatering appar-
atus such as a vacuum filter).  Filter aids generally increase perme-
ability by physically disrupting the packing of the sludge as the filter
cake forms, providing more channels or openings through which water
may pass.                                                     [

Recognizing the versatility of these types of conditioners, two
different, but related studies were conducted.  The major study dealt
with the application of flocculants and filter aids as an aid to
filtration operations.  The second study dealt with the application
of the same flocculants as an aid to clarification.

Flocculants were evaluated primarily as they applied to dewatering;
however, these conditioners could be applied to a slurry before it
entered the clarifier and simultaneously enhance both settling rates
and dewaterability.  Accordingly, a flocculant was selected for each
                                  35

-------
sludge in terms of improved dewaterability.  The same flocculant
was then evaluted for any secondary benefits such as increased set-
tling rates.
Equipment

Sludge conditioning investigations emphasizing filtration applications
were conducted using a Buchner funnel filtrate recovery test.  The
Buchner funnel test was used because it is a commonly accepted labor-
atory procedure that simulates vacuum filtration operations.  An
illustration of the Buchner funnel apparatus is presented in Figure
12.  The equipment used for the tests was an 11 centimeter Buchner
funnel, Whatman Number 5 filter paper, two 1000 milliliter vacuum
flasks, a vacutim gauge and a small vacuum pump.  The two vacuum
flasks were connected in series to the vacuum pump, the one closest
to  the pump fitted with the vacuum gauge and the other holding the
Buchner funnel.  A glass "T" was placed in the hose between the vacuum
gauge and the pump with a short piece of tubing and a pinch clamp
attached to the leg of the "T".  The pinch clamp was used as a relief
valve to control the vacuum.

The settling rate (clarification) tests were performed using two 1000
milliliter graduated cylinders and two 1000 milliliter volumetric
flasks.
 Filtration Procedure

 The initial  step in performing a Buchner funnel filtrate recovery test
 was preparation of the  flocculant sample.  Each flocculant examined was
 mixed with distilled water to obtain a 0.25 weight percent stock solu-
 tion.   The proper amount of stock solution to give the desired floccu-
 lant concentration was  volumetrically added to a graduated cylinder
 and diluted  with distilled water to a volume of 30 milliliters.  In this
 manner  the percent solids concentration of the sludge was always altered
 by  a fixed amount for each test and variations in filtrate recovery were
 not due to a change in  solids content.

 The 30  milliliter flocculant solution was placed in one beaker and 100
 milliliters  of the sludge to be tested was placed in another beaker.  The
 contents of  the beakers were mixed by pouring the flocculant into the
 sludge  and then pouring the mixture from one beaker to the other five
 times.   The  degree of mixing was thereby held constant.

 A piece of filter paper was placed in the Buchner funnel, wetted and
 vacuum  applied to seal  the paper to the funnel.  The vacuum was then
 released,  the flask emptied and the conditioned sludge poured into
 the funnel.   The vacuum was applied for one minute, released and the

                                  36

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Figure 12- BUCHNER FUNNEL  APPARATUS

-------
amount of filtrate recovered was measured and recorded.

For control purposes, the untreated sludge was tested using 30 mis
of distilled water and the filtrate recovery was compared to the
filtrate recovery results from the same test using conditioned
sludge.

A total of 62 flocculants were examined in the first series of tests
in conjunction with a lime sludge using the Buchner funnel test.  Each
flocculant was tested at various concentrations ranging from approximately
1 ppm to 115 ppm.  The increase in filtrate recovery and optimum concen-
trations were recorded for a large number of cationic, anionic and
non-ionic flocculants.

Filter aids (materials like diatomaceous earth which act to improve
the porosity of a filter cake) were studied in !a similar manner
except that the desired amount of dry filter aid was poured into a
graduated cylinder and distilled water was added to create a total
volume of 30 milliliters.  The 30 milliliter filter aid-water mix-
ture was then mixed with 100 milliliters of the sludge.  The sludge-
filter aid mixture was then examined against an untreated sludge
using the Buchner funnel test.

Six different filter aids were used on Norton sludge (a limestone
treatment sludge) and the results examined.

Following the first series of tests, the best flocculants and/or
filter aids were selected using a 30 percent or greater increase in
filtrate recovery over the control filtrate recovery as a criteria.
Using the Buchner funnel test again these selected flocculants were
then tested against the four characteristic mine drainage sludges.
From these tests the best conditioner and its optimum concentration
was determined for each sludge.
Settling Rate  (Clarification)

Sludge conditioning studies using flocculants were carried further into
the area of clarification.  Settling rate tests were conducted at the
respective treatment plants using the flocculant at its optimum con-
centration found for that sludge from the previous Buchner funnel
tests.
            ;    •   i            '

Two 1000 milliliter volumetric flasks were prepared, one having a 100
milliliter flocculant solution in it and the other 100 milliliters of
distilled water.  Both flasks were then filled with 900 milliliters of
sludge slurry collected just before it entered the settling lagoon or
clarifier.'  The two flasks were emptied into 1000 milliliter graduated
                                  38

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cylinders and Che timing clock started.  As the sludges settled, in-
terface readings were taken at various times during the test along with
remarks as to the relative clarity of the water above the interface.
In the case of the Norton slurry, this procedure could not be followed
as a definite interface did not form.  On those occasions the only data
taken was a relative clarity, with and without flocculants, at
various time intervals.
Filtration Results

Based upon the results of the initial screening test presented in
Table 7, 14 flocculants were found to give an increase in filtrate
recovered of 30 percent or greater.  These 14 selected flocculants
were all anionic and had a medium to high atomic weight relative
to the other flocculants tested.  The results of the initial
screening test for filter aids is shown in Table 8.  None of the
filter aids gave an increase in filtrate recovered of over 30 per-
cent.  Filter aids were thereby eliminated from further study.

The results of the detailed evaluation of the 14 selected flocculants
are shown in Tables 9 -through 12.  Shannopin sludge responded best
to the use of flocculants; however, it required a relatively large
dosage for maximum effect.  Norton sludge on the other hand responded
the least to the use of flocculants although maximum effect was obtained
at a relatively small dosage.  From this latter series of tests a floc-
culant for each of the four sludges was selected on the basis of greatest
increase in filtrate recovered for that sludge.  Each sludge was con-
ditioned with its best flocculant in later dewatering studies.  The
selected flocculants are listed below:

1.  Shannopin Sludge - Nalcolyte 673 at 111.0 ppm
2.  Banning Sludge - Coagulant 2350 at 37.0 ppm
3.  Edgell Sludge - Hercofloc 831 at 111.0 ppm
4.  Norton Sludge - Decolyte 940 at 37.0 ppm
Clarification Results

The settling curves for Shannopin, Banning and Edgell sludges, all of
which settle with a distinct interface, are shown on Figures 13 through
15.  The settling curves for sludges without flocculant may differ
somewhat from those shown in Figures 5 through 7 due to variances
in the water treated at the same treatment plant on different days.
The variance in the water treated causes a variance in the sludge
produced and therefore alters the settling rates.

All of the sludges settled faster with a flocculant and all showed
some increase in water clarity; however, the improvement is probably
                                  39

-------
not enough to justify their use for clarification alone.  In interpre-
ting these settling curves it must be remembered that these flocculants
were selected with increased filtration rates as a criteria rather
than increased settling rates.

Norton sludge was tested with a flocculant and while no interface
could be detected the sludge did not appear to settle faster with a
flocculant and did not produce a clearer water.
                                  40

-------
                                Table 7

              Effect of Flocculants on Filtrate Increase
                             Lime Sludges

    (Unit costs based on purchase quantity of 1,000 pounds,  F.O.B.)
Unit
Cost
$1.25/lb.
$1.25/lb.
$1.25/lb.
$1.25/lb.
$1.35/lb.
$1.25/lb.
$0.24/lb.
Flocculant
Flocculant Tested Type
*Allied Colloids, Inc. anionic
Percol 139
Allied Colloids, Inc. cationic
Percol 140
Allied Colloids, Inc. anionic
Percol 155
*Allied Collids, Inc. anionic
Percol 156
Allied Colloids, Inc. cationic
Percol 292
Allied Colloids, Inc. nonionic
Percol 351
American Cyanamid Co. cationic
Optimum
Flocculant
Concentration
(ppm)
11.1
2.9
11.1
18.5
5.8
3.9
111.0
Filtrate
Increase Flocculant
With Cost Per
Flocculant 1000
(percent) Gallons
39.7 $0.12
5.1 $0.03
23.2 $0.12
63.2 $0.19
1.6 $0.06
7.3 $0.04
9.0 $0.22;
Magnifloc 521 C

-------
                           Table 7  (Continued)
Unit
Cost
$0.28/lb.
**NA
**NA
$1.35/lb.
$1.35/lb.
$1.50/lb.
$1.50/lb.
$1.25/lb.
$1.25/lb.
Flocculant Tested
American Cyanamid Co.
Magnifloc 560 C
American Cyanamid Co.
Magnifloc 570 C
American Cyanamid Co.
Magnifloc 571 C
American Cyanamid Co.
Magnifloc 835 A
American Cyanamid Co.
Magnifloc 836 A
American Cyanamid Co.
Magnifloc 837 A
American Cyanamid Co.
Magnifloc 905 N
American Cyanamid Co.
Superfloc 16
American Cyanamid Co.
Flocculant
Type
cationic
cationic
cationic
anionic
anionic
anionic
nonionic
nonionic
nonionic
Optimum
Flocculant
Concentration
(ppm)
	
3.7
37.0
18,5
3.7
w
—
2.9
2.9
Filtrate
Increase
With
Flocculant
(percent)
0.0
0.5
3.4
20.1
25.8
23.0
0.0
1.6
4.2
Flocculant
Cost Per
1000
Gallons
	
NA
NA
$0.21
$0.04
$0.02
	
$0.03
$0.03
Superfloc 20

-------
                           Table 7 (Continued)


Unit
Cost
$1.30/lb.

$1.30/lb.

$1.25/ Ib.

$0.40/lb.

$1.65/lb.

$2.25/lb.

$2.25/lb.

$1.92/lb.

$1.92/lb.



Flocculant Tested
American Cyanamid Co.
Superflpc 84
American Cyananid Co.
Superfloc 127
American Cyanamid Co.
Superfloc 202
American Cyanamid Co.
Superfloc 310
*Calgon Corp.
Calgon 240
Calgon Corp.
Coagulant 2256
Calgon Corp.
Coagulant 2260
Calgon Corp.
Coagulant 2300
Calgon Corp.


Flocculant
Type
nonionic

nonionic

anionic

cationic

anionic

cationic

cationic

nonionic

anionic
Optimum
Flocculant
Concentration
(ppm)
3.9

1.9

1.9

1.9

25.9

5.8

5.8

5.8

3.9
Filtrate
Increase
With
Flocculant
(percent)
6.9

5.7

21.7

1.8

68.3

0.5

3.8

1.8

3.7
Flocculant
Cost Per
1000
Gallons
$0.04

$0.02

$0.02

$0.01

$0.04

$0.11

$0.11

$0.09

$0 . 06
Coagulant 2325

-------
                                         Table 7 (Continued)
Unit
Cost
$1.92/lb.
$1.92/lb.
$1.92/lb.
*• **NA
**NA
«.«/».
**NA
Flocculant Tested
*Calgon Corp.
Coagulant 2350
*Calgon Corp.
Coagulant 2400
*Calgon Corp.
Coagulant 2425
Diamond Shamrock Corp.
Decolyte 710
Diamond Shamrock Corp.
Decolyte 720
*Diamond Shamrock Corp.
Decolyte 930
*Diaraond Shamrock Corp.
Flocculant
Type
anionic
anionic
anionic
cationic
cationic
anionic
anionic
Optimum
Flocculant
Concentration
(ppm)
55.5
18.5
111.0
3.7
1.9
3.7
Filtrate
Increase
With
Flocculant
(percent)
37.0
41.9
50.0
0.0
3.6
32.9
45.3
Flocculant
Cost Per
1000
Gallons
$0.09
$0.30
$1.78
NA
$0.04
NA
**NA
**NA
Decolyte 940

Diamond Shamrock Corp.
Decolyte 950

*Dow Chemical Co.
Purifloc A-21
anionic
anionic
  3.7
111.0
28.0
40.4
NA
NA

-------
                                              Table 7 (Continued)
Ui
Unit
Cost
$1.30/lb.
$1.35/lb.
$0.45/lb.
$0.45/lb.
$1.50/lb.
$1.50/lb.
$1.50/lb.
*NA
$0.30/lb.
Flocculant Tested
Dow Chemical Co.
Separan AF 30
*Dow Chemical Co.
Separan AP 273
Drew Chemical Corp.
Drewfloc 3
Drew Chemical Corp.
Drewfloc 3
Drew Chemical Corp.
Drewfloc 6
Drew Chemical Corp.
Drewfloc 6
Drew Chemical Corp.
Drewfloc 230
Drew Chemical Corp.
Drewfloc 230
Drew Chemical Corp.
Flocculant
Type
anionic
anionic
anionic
cationic
anionic
cationic
anionic
cationic
anionic
Optimum
Flocculant
Concentr a tion
(ppra)
37.0
11.1
1.9
	
0.4
5.8
2.9
1.9
0.6
Filtrate
Increase
With
Flocculant
(percent)
23.3
31.3
12.0
0.0
9.8
5.7
8.0
5.7
10.2
Flocculant
Cost Per
1000
Gallons
$0.40
$0.13
$0.01
	
$0.01
$0.07
$0.04
NA
$0.01
                    Drewfloc 410

-------
                            Table 7 (Continued)
Unit
Cost
$1.35/lb.
$1.50/lb.
$1.25/lb.
$1.25/lb.
$1.25/lb.
$1.25/ Ib.
$1.25/lb.
$0.49/lb.
$0.31/lb.
Flocculant Tested
Hercules , Inc .
Hercofloc 812
Hercules, Inc.
Hercofloc 815
*Hercules, Inc.
Hercofloc 818
Hercules , Inc .
Hercofloc 821
Hercules, Inc.
Hercofloc 827
*Hercules, Inc.
Hercofloc 831
Hercules, Inc.
Hercofloc 834
Nalco Chemical Co.
Nalcolyte 110 A
Nalco Chemical Co.
Flocculant
Type
cationic
cationic
anionic
anionic
nonionic
anionic
cationic
nonionic
cationic
Optimum
Flocculant
Concentration
(ppm)
2.9
5.8
11.1
5.8
1.0
18.5
1.9
1.0
0.2
Filtrate
Increase
With
Flocculant
(percent)
1.9
12.7
57.4
21.2
4.5
60.3
12.5
3.2
3.3
Flocculant
Cost Per
1000
Gallons
$0.03
$0.07
$0.12
$0.06
$0.01
$0.19
$0.02
$0.01
$0.01
Nalcolyte 603

-------
                                         Table 7 (Continued)
Unit
Cost
$1.37/lb.
$2.06/lb.
$1.76/lb.
$1.73/lb.
$0.11/lb.
Flocculant Tested
Nalco Chemical Co.
Nalcolyte 670
Nalco Chemical Co.
Nalcolyte 672
*Nalco Chemical Co.
Nalcolyte 673
Nalco Chemical Co.
Nalcolyte 675 H
Narvon Mining and
Flocculant
Type
nonionic
anionic
anionic
anionic
cationic
Optimum
Flocculant
Concentration
(ppm)
	
1.9
18.5
5.8
1.9
Filtrate
Increase
With
Flocculant
(percent)
0.0
11.4
41.7
19.4
6.8
Flocculant
Cost Per
1000
Gallons
	
$0.03
$0.27
$0.08
$0.01
$0.117Ib.
  Chemical Co.
Zeta Floe S

*Narvon Mining and
  Chemical Co.
Zeta Floe WA

Narvon Mining and
  Chemical Co.
Zeta Floe WA3

Narvon Mining and
  Chemical Co.
Zeta Floe WA5
                                             anionic
anionic
                                             anionic
                   5.8
1.9
                   1.9
                 31.4
13.7
                 19.0
                $0.01
$0.01
                                                                                                 $0.01

-------
                                             Table 7 (Continued)
  Unit
  Cost

$17.75/100
    $0.18/lb.
  Flocculant Tested

National Starch and
  Chemical Co.
Natron 86

Rohm and Hass Co.
Primafloc A 10
                                               Flocculant
                                                  Type

                                                cationic
anionic
                  Optimum
                 Flocculant
                Concentration
                    (ppm)
5.8
             Filtrate
             Increase
               With
             Flocculant
              (percent)

                 0.0
26.6
             Flocculant
              Cost Per
                1000
              Gallons
                                                                                                 $0.01
00
           Average increase in recovery for all flocculants  - 17.3%
                 Average increase in recovery with anionics  - 30.0%
                Average increase in recovery with cationics  -  3.9%
                Average increase in recovery with nonionics  -  3.5%
     Selected for further study.
    **
     This  flocculant no longer manufactured,  price not available.

-------
                               Table 8

             Effect of Filter Aids on Filtrate Increase
                    Norton Treatment Plant Sludge
                    (Average Percent Solids 4.1)

   (Unit costs based on purchase quantity of 1,000 pounds, F.O.B.)


Unit
Cost
*- $0.50/ ton
\O
$50.80/ton

$160.00/ton
•
$160.00/ton

$160.00/ton

$0.50/ ton

Optimum
Material Used As Concentration
Filter Aid (ppm)
Municipal Incinerator 	
Fly ash
-Bituminous Coal 3,850
crushed to -60 mesh
Johns-Manville 3,850
Hyflo Super-Cell
Johns-Manville 3,850
Celite 501
Johns-Manville 3,850
Celite 503
Wet Collected

Filtrate Increase With
Filter Aid
(percent)
0.0

6.2

8.4

10.8

3.2


Flocculant
Cost Per
1000
Gallons


$0.82

$2.57

$2.57

$2.57


limestone modified
flyash
40,000
2.7
$0.08

-------
                                  Table 9

             Effect of Selected Flocculants on Filtrate Increase
                      Shannopin Treatment Plant Sludge
                        (Average Percent Solids 5.3)

       (Unit costs based on purchase quantity of 1,000 pounds, F.O.B.)
Unit
Cost
$1.25/lb.
$1.25/lb.
$1.65/lb.
$1.92/lb.
$1.92/lb.
$1.92/lb.
$1.41/lb.
Flocculant Tested
Allied Colloids, Inc.
Percol 139
Allied Colloids, Inc.
Percol 156
Calgon Corp.
Calgon 240
Calgon Corp.
Coagulant 2350
Calgon Corp.
Coagulant 2400
Calgon Corp.
Coagulant 2425
Diamond Shamrock Corp.
Optimum Flocculant
Concentration (ppm)
55.5
37.0
74.0
44.4
44.4
44.4
111.0
Filtrate Increase
With Flocculant
(percent)
56.5
54.2
58.3
61.7
57.4
56.0
10.1
Flocculant
Cost Per
1000
Gallons
$0.58
$0.39
$1.02
$0.71
$0.71
$0.71
$1.31
Decolyte 930

-------
                                         Table 9  (Continued)
Unit
Cost
**NA
**NA
$1.35/lb.
$1.25/lb.
$1.25/lb.
$1.76/lb.
$0.11/lb.

Flocculant Tested
Diamond Shamrock Corp.
Decolyte 940
Dow Chemical Co.
Purif loc A 21
Dow Chemical Co.
Separan AP 273
Hercules, Inc,
Hercofloc 818
Hercules, Inc.
Hercofloc 831
Nalco Chemical Co.
Nalcolyte 673
Narvon Mining and
Chemical Co.
Zeta Floe WA
Average
Optimum Flocculant
Concentration (ppm)
111.0
111.0
55.5
44.4
74.0
111.0
111.0
73.5
Filtrate Increase
With Flocculant
(percent)
32.1
58.7
60.0
50.0
65.9
13.7
13.7
50.1
Flocculant
Cost Per
1000
Gallons
NA
NA
$0.63
$0.46
$0.77
$1.63
$0.10

**
 This flocculant no longer manufactured, price not available.

-------
                                                 Table 10

                            Effect of Selected Flocculants on Filtrate Increase
                                        Banning Treatment Plant Sludge
                                          (Average Percent Solids 1.2)

                       (Unit costs based on purchase quantity of 1,000 pounds,  F.O.B.)
N>
Unit
Cost
$1.25/lb
$1.25/lb.
$1.65/lb.
$1.92/lb.
$1.92/lb.
$1.92/lb.
$1.4l/lb.
Flocculant Tested
Allied Colloids, Inc.
Percol 139
Allied Colloids, Inc.
Percol 156
Calgon Corp.
Calgon 240
Calgon Corp.
Coagulant 2350
Calgon Corp.
Coagulant 2400
Calgon Corp.
Coagulant 2425
Diamond Shamrock Corp.
Optimum Flocculant
Concentration (ppm)
11.1
25.9
25.9
37.0
37.0
18.5
1.9
Filtrate Increase
With Flocculant
(percent)
19.3
25.3
23.7
42.8
32.9
30.3
32.9
Flocculant
Cost Per
1000
Gallons
$0.12
$0.27
$0.36
$0.59
$0.59
$0.30
$0.02
               Decolyte 930

-------
                                        Table 10 (Continued)
Unit
Cost
**NA
**NA
$1.35/lb.
$1.25/lb.
$1.25/lb.
$1.76/lb.
$0.11/ln.

Flocculant Tested
Diamond Shamrock Corp.
Decoiyte 940
Dow Chemical Co.
Purifloc A 21
Dow Chemical Co.
Separan AP 273
Hercules, Inc.
Hereof loc 818
Hercules, Inc.
Hercofloc 831
Nalco Chemical Co.
Nalcolyte 673
Narvon Mining and
Chemical Co.
Zeta Floe WA
Average
Optimum Flocculant
Concentration (ppm)
3.7
37.0
11.1
11.1
25.9
111.0
37.0
28.2
Filtrate Increase
With Flocculant
(percent)
41.1
25.6
31.3
19.0
37.1
26.7
33.8
30.1
Flocculant
Cost Per
1000
Gallons
NA
NA
$0.12
$0.12
$0.27
$1.63
$0.03

**
 This flocculant no longer manufactured, price not available.

-------
                                  Table 11

             Effect of Selected Flocculants on Filtrate Increase
                        Norton Treatment Plant Sludge
                         (Average Percent Solids 4.1)

        (Unit costs based on purchase quantity of 1,000 pounds, F.O.B.)


Unit
Cost
$1.25/lb.
$1.25/lb.
$1.65/lb.
$1.92/lb.
$1.92/lb.
$1.92/lb.
$1.41/lb.


Flocculant Tested
Allied Colloids, Inc.
Percol 139
Allied Colloids, Inc.
Percol 156
Calgon Corp.
Calgon 240
Calgon Corp.
Coagulant 2350
Calgon Corp.
Coagulant 2400
Calgon Corp.
Coagulant 2425
Diamond Shamrock Corp.


Optimum Flocculant
Concentration (ppm)
3.7
9.3
55.5
11.1
18.5
7.4
25.9

Filtrate Increase
With Flocculant
(percent)
15.7
12.6
12.7
6.5
14.9
18.4
.26.1
Flocculant
Cost Per
1000
Gallons
$0.04
$0.10
$0.76
$0.18
$0.30
$0.12
$0.30
Decolyte 930

-------
                                        Table 11 (Continued)
Unit
Cost
**NA
**NA
$1.35/lb.
$1.25/lb.
$1.25/lb.
$1.76/lb.
$0.11/lb.

Flocculant Tested
Diamond Shamrock Corp.
Decolyte 940
.*•
Dow Chemical Co.
Purifloc A 21
Dow Chemical Co.
Separan AP 273
Hercules , Inc .
Hercofloc 818
Hercules , Inc .
Hercofloc 831
Nalco Chemical Co.
Nalcolyte 673
Narvon Mining and
Chemical Co.
Zeta Floe WA
Avet
Optimum Flocculant
Concentration (ppm)
37.0
55.5
37.0
37.0
37.0
37.0
111.0
:age 34.5
Filtrate Increase
With Flocculant
(percent)
31.7
25.6
13.5
20.8
13.5
17.3
12.2
17.3
Flocculant
Cost Per
1000
Gallons
NA
NA
$0.42
$0.39
$0.39
$0.54
$0.10

**
 This flocculant no longer manufactured, price not available,

-------
                                  Table 12

             Effect of Selected Flocculants on Filtrate Increase
                         Edgell Treatment Plant Sludge
                           (Average Percent Solids 3.6)

        (Unit costs based on purchase quantity of 1,000 pounds, F.O.B.)
Unit
Cost
$1.25/lb.
$1.25/lb.
$1.65/lb.
$l,92/lb.
$1.92/lb.
$1.92/lb.
$1.41/lb.
Flocculant Tested
Allied Colloids, Inc.
Percol 139
Allied Colloids, Inc.
Percol 156
Calgon Corp.
Calgon 240
Calgon Corp.
Coagulant 2350
Calgon Corp.
Coagulant 2400
Calgon Corp.
Coagulant 2425
Diamond Shamrock Corp.
Optimum Flocculant
Concentration (ppm)
25.9
92.5
37.0
37.0
92.5
74.0
111.0
Filtrate Increase
With Flocculant
(percent)
16.7
42.2
67.8
50.0
35.4
55.8
19.8
Flocculant
Cost Per
1000
Gallons
$0.27
$0.96
$0.51
$0.59
$1.48
$1.19
$1.30
Decolyte 930

-------
                                        Table 12 (Continued)
Unit
Cost
**NA
**NA
$1.35/lb.
u. $1.25/lb.
•>4
$1.25/lb.
$l,76/lb.
$0.11/lb.

Flocculant Tested
Diamond Shamrock Corp.
Decolyte 940
Dow Chemical Co.
Purif loc A 21
Dow Chemical Co.
Separan AP 273
Hercules, Inc.
Hercofloc 818
Hercules, Inc.
Hercofloc 831
Nalco Chemical Co.
Nalcolyte 673
Narvon Mining and
Chemical Co.
Zeta Floe WA
Averai
Optimum Flocculant
Concentration (ppm)
111.0
92.5
81.4
111.0
111.0
111.0
111.0
ee 85.6
Filtrate Increase
With Flocculant
(percent)
24.0
22.2
55.8
50.0
73.8
53.3
4.5
40.8
Flocculant
Cost Per
1000
Gallons
NA
NA
$0.92
$1.15
$1.15
$1.63
$0.10

**
 This flocculant no longer manufactured, price no available.

-------
             100
oo
              80
     60
SETTLED

SO LIDS -

% VOLUME
     40
             20
                        10
                        20       30      40
                        SETTLING TIME-MINUTES
50
60
        Figure 13- SETTLING RATE OF CONDITIONED MIXING TANK SLUDGE
                 FROM  SHANNOPIN TREATMENT PLANT

-------
           100
vO
            80
      60
SETTLED
SOLIDS-
%VOLUME
      4O
            20
                        With Floccu I ant ( Cocci
                               20       30      40
                               SETTLING TIME-MINUTES

      Figure 14-SETTLING RATE OF CONDITIONED  AERATOR SLUDGE  FROM
               BANNING TREATMENT PLANT

-------
     100
      80
     60
SETTLED
SOLIDS-
%VOLUME
     40
     20
                          ant (Hereof toe 831 )
                10
50
                         20       30      40
                          SETTLING TIME-MINUTES
Figure 15-SETTLING RATE OF CONDITIONED AERATOR SLUDGE FROM
         EDGELL  TREATMENT PLANT
60

-------
                              SECTION VI

                           SLUDGE DEWATERING

The primary objective of this research was to evaluate various de-
watering systems as they apply to the sludge produced by the neutrali^
zation of acid mine drainage.  The systems evaluated were:

1.  Conventional Rotary Vacuum Filtration
2.  Rotary Precoat Vacuum Filtration
3.  Pressure Filtration
4.  Porous Bed Filtration
5.  Thermal Spray Drying
6.  Centrifugation

The evaluation of each of the above dewatering systems is presented
in four parts.  The first part is a brief discussion of the dewatering
system as used in industry.  This section includes a brief description
of a commercial size unit of the dewatering system and its general
method of operation.  The second part is a description of the test
apparatus used.  Generally the test equipment was bench scale; however,
some of the dewatering systems were studied on a semi-pilot plant
scale.  The procedure used in making the dewatering tests is described
in the third section.  And the fourth section is a discussion of the
results of the bench scale tests.  The results section is intended
to show whether it is technically feasible to dewater each of the
four sludges by the method in question and to compare the relative
efficiency of this method on each sludge.

The results obtained with these different systems vary with changes in
the solids content of the sludge to be dewatered.  Also, the sludge
collected from the settling lagoons of Shannopin, Norton and Edgell
varied in solids content with each field trip.  Since the sludge was
pumped from below several feet of water varying amounts of water would
be pulled into the pump with the sludge.  Banning sludge was collected
as underflow from the clarifier and showed no significant change in
solids content, averaging very close to 0.5 percent solids.  In order
to maintain a fair basis for comparison of the various dewatering
systems it was necessary to assign a solids content for each sludge
as follows:  Shannopin sludge 2.1 percent, Edgell sludge 2.7 percent
and Norton sludge 8.0 percent.  In some cases additional work was
done at a higher or lower solids content than that specified in order
to determine the effect of a variance in solids content on a specific
dewatering system.  If the solids content of a sludge as collected
was found to be less than the desired solids content, it was allowed
to settle and some water decanted until the correct solids content
was obtained.  In cases where the solids content as collected was too
high, treated water from the plant in question was added until the
solids content was correct.
                                  61

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                    Conventional Vacuum Filtration
General

A conventional rotary vacuum filtration unit consists of a horizontal
drum covered with a filter media.  Vacuum is applied to segments of  the
filter media from within the drum as the drum is rotated.  As the
filtrate is pulled through the filter media the solids are deposited
on the media.

Rotary vacuum filtration may be divided into three phases.  The first
phase is filtration which occurs on a portion of the drum during the
time when that portion of the drum is submerged in the sludge.  As a
segment of the drum rotates into the sludge, vacuum is applied and fil-
trate is drawn through the filter media and discharged.  Concurrently,
sludge solids are deposited on the filter media face to form a cake.
As the sludge cake becomes thicker, its resistance to the passage of
filtrate increases.  The drum speed and amount of submergence of the
drum are adjusted such that each segment of the drum leaves the slurry
before the increasing cake resistance reduces the filtrate flow rate
below an acceptable level.

The second phase of the operation occurs during the time a segment of
the drum leaves the sludge and before the cake is removed.  It is during
this time that the cake is dried.  As the drum leaves the sludge the
cake is still under vacuum and additional moisture contained within
the cake is drawn out.  This phase may be of varying length de-
pending on the desired dryness of the cake and the time required to
achieve this dryness.  The cake has reached its highest practical degree
of dryness when it cracks as air will then be drawn through the cracks
in the cake rather than through the cake itself.

The third phase, cake removal, begins after the cake has reached
acceptable dryness.  At this point the vacuum is removed and the
cake is discharged.  The most common types of conventional cake dis-
charge devices are a scraper discharge, a wire discharge or a string
discharge.  The scraper, the most commonly used type, is a sharp
blade which is mounted on the side of the filter tank and scrapes
the filter cake from the drum.  However, when thin sticky cakes are
encountered, a taut longitudinal wire may be used.  The longitudinal
wire is under great tension and is fixed in the same position as the
scraper tip; this allows the cake to be peeled off the drum.  When
cakes which adhere strongly to the filter cloth are encountered a
string type discharge may be used.  With the string type discharge,
annular strings are spaced about 3/8 inch apart and are around the
drum and on top of the filter cloth.  The strings are led from the
discharge point on the drum to a small roller away from the drum and
then back to the drum again.  The cake is supported by these strings.
As the strings leave the drum the cake is led off the drum and is
                                  62

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discharged at the sharp bend made by  the  roller  in  returning  the
string to the drum.t10'  All of  the operations described  are  of a
continuous nature so all three phases are occurring simultaneously
on different portions of the drums surface.
Test Apparatus - Description

Bench scale experiments were performed with a 0,1 square foot surface
area, Dorr-Oliver filter leaf apparatus shown in Figure 16.  This
leaf was designed to simulate the  function of an equal area on the sur-
face of a full size conventional rotary vacuum  filtration drum.

The filter leaf was connected to two graduated  receivers by hoses and
a two way valve.  The vacuum source was connected to  the receivers in
a like manner so that one receiver could be collecting filtrate while
the other was being vented and drained.  The vacuum source consisted
of a small vacuum pump which was connected by a hose  to a 1000 milli-
liter volumetric flask.  The flask was equipped with  a vacuum gage
which registered inches of mercury and an air bleed to reduce vacuum
to the leaf.  The purpose of the flask was to keep water from being
pulled into the vacuum pump.  The  test apparatus also included a four
liter container which held the sludge to be tested.   The sludge was
stirred manually with a glass rod  in order to keep the sludge parti-
cles in suspension.

Various filter cloths from Eimco Filter Media Corporation and National
Filter Media Corporation were used in these tests.
Procedure

The three phases of a rotary vacuum  filtration  cycle were duplicated
with the filter leaf.  First the  filter  leaf was  submerged  in the
sludge container under vacuum  to  duplicate  the  filtration phase of
the filter drum's cycle.  Second  the filter leaf  was lifted from the
sludge and placed face up on a ring  stand to duplicate  the  drying
phase.  The third phase involved  removing the built up  sludge cake
by scraping it away after air  had been applied  behind the filter media
to loosen the cake.  As with rotary  vacuum  filtration,  the  filter media
was under vacuum for the entire cycle except for  cake discharge.
The amount of vacuum used was  24  to  25 inches of  Hg.

Since a minimum cake thickness of 1/8 inch  was  necessary to permit
proper discharge of the cake from the filter cloth,C11' the conditions
necessary to produce a 1/8 inch thick cake  were determined. Length
of the first phase of a conventional rotary vacuum  filtration cycle
(the submergence time of the leaf into the  sludge)  determines the
thickness of the cake formed.   By experimentation the length of time

                                  63

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Second
Timer
                                                         Two-Way
                                                          Valve
              Two-Way
               Valve
 Ring Stand With
Platform to Hold Test
Leaf While Drying
               Vacuum
                Gage
   Air Bleed to
     Reduce
  Vacuum to Leaf


To Vacuum
  Source
                                                               Rubber
                                                                Hose ""
                                                           Stirring
                                                            Rod\
                       Filter
                       Leaf
                                                        Slurry
                                                        Container
                                 To  Drain
 Figure  16-FILTER  LEAF APPARATUS

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required for a 1/8 inch cake build up for each  sludge was  found.  This
time was the minimum submergence time for the cycle.  For  the  second
phase the leaf was placed on a ring stand and vacuum dried.  The  dry-
ing time was found experimentally by allowing the  cake  to  dry  until
it cracked, at which time the cake had reached  its highest practical
degree of dryness.  The third phase of the cycle  (the time required
to remove the cake from the filter cloth) is constant depending upon
the type of machinery used.  The amount of filtrate recovered  each
cycle and the time required for the cake to crack  during drying along with
any observations as to condition of the sludge  cake were recorded.
After the optimum cycle time was established for a sludge, the sludge
cake formed was analyzed for solids content on  an  Ohaus moisture
determination balance.

All four sludges, with and without flocculants, were studied in the
same manner.  The sludge was conditioned with the  flocculant that
was found in the earlier Buchner funnel tests to give the  highest
increase in filtration rates.
Results

Results obtained with conventional  rotary vacuum  filtration were
good for Norton sludge but poor  for Banning, Edgell and Shannopin
sludges.

In the  tests 38 filter cloths  from  Eimco Corporation and 5 filter
cloths  from National Corporation were  investigated with a lime neu-
tralized sludge.  Of these 43  different cloths  four were chosen
according to best filtrate clarity  and best  filtration rates obtained.
These four cloths were all from  Eimco  Corporation and were NY-301,
CO-3, NY-518F, and Popr-913F.  These cloths  were  tested with each
of the  four sludges both with  and without the optimum concentration
of flocculant added as determined by Buchner funnel tests.  It was
found that filter cloth CO-3 gave the  best results for Banning, Edgell
and Norton sludges and cloth NY-301 gave the best results for Shannopin
sludge.  Results on the four sludges and their  respective filter cloths
are shown in Tables 13 through 16.

A minimum sludge cake build up of 1/8  inch is necessary to allow
proper  discharge of the cake from the  filter cloth.  Vacuum filters
are normally designed with a variable  speed  drive to operate at
between 1 to 10 minutes per revolution (mpr).   This would mean
that cake formation time for a 1/3  submergence  drum cannot exceed
3 1/3 minutes.  A drum with 1/2  or  greater submergence was not
considered due to high capital and  operating costs.  If a cake
thickness of 1/8 inch or greater can be formed  in this time, a
conventional vacuum filter should be considered.  If the cake thick-
                                   65

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                                             Table 13

                                   Conventional Vacuum Filtration
                                  Shannopin Treatment Plant Sludge

                                     Filter Cloth - Eimco NY  301
                                                           Filtrate
Feed
Solids
(percent)
2.4
2.4*
4.2
4.0*
Dip
Time
(min)
•^"••••••MMB*
10
10
10
5
Time
to
Crack
(sec)
120
17
30
420
Sludge
Dewatered
(gal/sq ft/min)
0.0576
0.0731
0 .0280
0.0474
Quality
Nonfilterable
Solids
(ppm)
997
23
343
25
Cake
Thickness
(in)
0.1250
0.1250
0.3750
0.1875
Solids
(percent)
17.0
12.6
15.1
15.5
With Nalcolyte 673 added  (flocculant)

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                                             Table 14

                                  Conventional Vacuum Filtration
                                  Banning Treatment Plant Sludge

                                     Filter Cloth - Eimco CO-3
                                                           Filtrate
Feed
Solids
(percent)
0.4
0.4*
2.2
2.1*
Dip
Time
(min)
5
10
5
5
Time
to
Crack
(sec)
25
20
120
120
Sludge
Dewatered
(gal/sq ft /min)
0.1237
0.0845
0.0694
0.0712
Quality
Nonfilterable
Solids
(ppm)
618
23
42
3
Cake
Thickness
(in)
0.125
0.125
0.250
0.250
Solids
(percent)
11.2
9.2
8.8
10.1
With Coagulant 2350 added (flocculant)

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                                                   Table  15

                                        Conventional  Vacuum  Filtration
                                        Norton  Treatment Plant  Sludge

                                        Filter  Cloth - Emico  -  CO-3
                                                                 Filtrate
00
Feed
Solids
(percent)
8.1
8.1*
12.3
12.3*
Dip
Tine
(min)
20
20
20
20
Time
to
Crack
(sec)
15
10
20
20
Sludge
Dewatered
(gal/sq f t/min)
0.1140
0.1910
0.1660
0.1660
Quality
Nonfilterable
Solids
(pptn)
33
13
-

Cake
Thickness
(in)
0.1250
0.1875
0.3750
0.3750
Solids
(percent)
19.8
19.2
21.3
20.3
     With Decolyte 940 (flocculant)

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                                                  Table 16

                                       Conventional Vacuum Filtration
                                        Edgell Treatment Plant Sludge

                                         Filter Cloth - Emico - CO-3
                                                                Filtrate
AO
Feed
Solids
(percent)
3.0
3.0*
6.8
7.2*
Dip
Time
(min)
10
10
10
10
Time
to
Crack
(sec)
70
60
300
260
Sludge
Dewatered
(gal/sq ft/min)
0.0323
0.0396
0.0321
0*0272
Quality
Nonfilterable
Solids
(ppm)
100
58
30
"
Cake
Thickness
(in)
0.0625
0.125
0.25
0.1875
Solids
(percent)
30.9
24.2
28.0
29.0
     With Hercofloc 831 added (flocculant)

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ness is less than this, then a precoat filter should be considered.

Of the four representative sludges only Norton produced a discharge-
able cake within the time limitation (3-1/3 minutes) imposed by a
conventional rotary vacuum filter unit.  It might be possible to use
special equipment to handle the other three sludges by conventional
vacuum filtration; however, the cost of such equipment would be high.

Norton sludge was tested at 8.1 and 12.3 percent solids both with
and without flocculant conditioning.  At 8.1 percent solids without
flocculant the best dip or submergence time was found to be 20 seconds.
This gave a cycle time of one minute at 1/3 submergence which is the
minimum cycle time required for conventional rotary vacuum filtration
and the minimum cake thickness of 1/8 inch was obtained.

When the flocculant was added to the 8.1 percent solids Norton sludge
there was an increase in filtration rate, filtrate clarity and cake
thickness.  These increases were not observed when the flocculant
was applied to the 12.3 percent solids Norton sludge.  However, the
final percent solids of the cake was not changed significantly with
the addition of the flocculant to the sludge for either the 8.1 or
the 12.3 percent solids Norton sludge.

The filtrate obtained from each of the four sludges using the best
available filter cloth generally was not of sufficiently high clarity
to warrant its discharge into a stream.
                   Rotary Precoat Vacuum Filtration

General

Rotary precoat vacuum filtration is similar to conventional rotary
vacuum filtration with one major exception; the application of a
precoat (generally diatomite) to the filter prior to actual filtra-
tion.  Diatomite is the siliceous skeletal remains of single - celled
aquatic plant life called diatoms.  The diatoms form a permeable
coating on the filter that allows the filtrate to pass through easily
while sludge solids are trapped, thereby producing a filtrate of very
high clarity.

The rotary precoat vacuum filtration unit, like the conventional rotary
vacuum filtration unit, consists of a horizontal drum that is covered
with a filter media.  Vacuum is applied to segments of the filter media
from within the drum and the drum is rotated.  Initially the drum is
immersed in a slurry of the precoat and an increasingly thick cake of
diatomite is formed on the drum as the fluid is pulled through the filter
media and the solids deposited on the media.  After the precoat has
                                  70

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reached sufficient thickness (several inches depending on the length
of time the filter is to be continuously operated), it is shaved
smooth and dewatering can now begin,

Rotary precoat vacuum filtration may be divided into three phases.  The
first and second phases are essentially the same as in conventional
rotary vacuum filtration.  The third phase, cake removal, begins when
the cake has reached acceptable dryness.  In practice the cake must
be removed before it cracks as cracking in the cake tends to cause
cracking and gouging of the precoat.  Before cracking occurs the cake
and a few thousandths of an inch of precoat are cut away by means of
a continuously advancing knife.  The sludge cake and the precoat are
then discharged.  The fresh surface of precoat now exposed by the cut
is rotated into the sludge once more to again start the filtration phase.
Test Apparatus - Description

Bench scale experiments were performed with a 0.1 square foot surface
area precoat filter leaf apparatus  rented  from Johns-Manville Research
Center.  This leaf, shown in Figure 17, was designed  to simulate the
function of an equal area on the surface of a full size rotary precoat
vacuum filtration drum.

The filter leaf was composed of two parts:  a collar  and within the
collar, a moveable septum that together act as a system to hold and
advance the precoat.

The septum (or filter media) was circular  and mounted on top of
a screw shaft that moves the septum up or  down within the cylindrical
collar.  An indicator fixed to the  screw regulates, in thousands of an
inch, movement of the septum within the collar.  The  filter leaf was
connected to two graduated receivers by hoses and a two way valve.
The vacuum source was connected to  the receiver in such a manner that
one receiver was collecting filtrate while the other  was vented and
being drained.  This dual setup allowed tests of indefinite duration
since one receiver could easily be  drained as the other was filled and
the flow of filtrate diverted to the freshly drained  receiver with
minimal effect on filtrate recovery.

To assure the stability of the apparatus the filter leaf was attached to
a mounting that provided support.   In addition to providing support the
mounting also allowed the leaf to rotate in both the  horizontal and
vertical directions.

The test apparatus also included a  small slurry tank  that had a 1.5
liter capacity.  The slurry tank was equipped with a  variable speed
agitator used to keep the sludge particles in suspension.

                                  71

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1 •
                                        . ...?..
                 Figure 17- PRECOAT  FILTER LEAF APPARATUS

-------
Procedure

Preparing the precoat filter leaf  for experimentation was done
in such a manner as to simulate the  formation of a precoat on a
full sized filter drum.  Precoating  was initiated by pouring
approximately 400 mis of a 2 percent by weight precoat slurry on
the filter leaf, allowing the precoat layer  to filter dry and repeating
the process until the desired precoat thickness was reached.  Alter-
nately adding slurry and filtering it dry produces a cake with a
laminar structure similar to that  which forms on a filter drum.
Great care had to be taken to avoid  erosion  when adding slurry onto an
already formed precoat.  After the precoat cake was formed, shrinkage
cracks were repaired by spooning the slurry  onto the surface and the
surface was shaved smooth.

Following the precoating operation,  the three phases of a rotary pre-
coat vacuum filtration cycle were  duplicated with  the filter leaf.
The filter leaf was submerged in the slurry  tank under vacuum to
duplicate the filtration phase of  a  filter drum's  cycle.  The filter
leaf was then lifted from the sludge and rotated to a vertical posi-
tion to duplicate the drying phase.  The third phase involved rotating
the leaf to a horizontal position, advancing the cake and cutting away
the sludge cake and a few mils of  precoat with a sharp knife.  When
the cake was advanced, a portion of  the precoat extended beyond the collar
of the filter leaf could easily be cut away. The  filter leaf was under
vacuum for the entire cycle.  The  vacuum used was  about 25 inches of Hg.

Four variables were examined during  the precoat filter leaf dip tests:
cycle time, depth of cut, type of  precoat and flocculant effects.

A test was initiated by first determining the optimum cycle time for a
sludge.  The following cycle times examined, which represent submer-
gence, drying and cutting times respectively, are  considered typical
for difficult to dewater sludges in  industrial operations:  20-15-10
seconds, 30-20-10 seconds and 45-35-10 seconds.  The cycle chosen
as being best was that which produced the highest  filtrate recovery
and an acceptably smooth cut.

After the best cycle time was chosen, the second variable, depth of
cut, was evaluated.  Depth of cut  refers to  the thickness of precoat
cut away with the sludge cake.  As a sludge  cake forms on the precoat
there was some penetration of the  precoat by the sludge particles.  The
depth of penetration depended on the sludge  being  dewatered and the
type of precoat used.  If the sludge particles were not removed from the
precoat they would cause a decrease  in permeability which is sometimes
called blinding.  To alleviate this  blinding during each cycle  the cut
had to be deep enough to remove all  of the particles.  Starting with the
15 mil cut used during the previous  cycle time  the cut was made progres-

                                   73

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sively shallower until filtration rates began to drop.  The point at
which filtration rates dropped represents the minimum usage of precoat
concurrent with the maximum filtration rates.

Following the study of the best cut for the initial type of precoat,
a different precoat was then evaluated.  The cycle time did not change
when investigating different precoats on the same sludge.  Therefore,
the optimum cut to allow maximum filtration was the only data taken
following a change from one precoat to another.

The last variable studied was the use of a flocculant to increase fil-
tration rates.  The sludge was conditioned with the flocculant that was
found by the Buchner funnel tests to give the highest increase in
filtration rates.  The same battery of tests (cycle time, depth of cut)
were employed on the flocculant conditioned sludge and the results
compared.  All four sludges were studied both preconditioned and non-
conditioned in the same manner using the tests described above.

The amount of filtrate recovered in each cycle was recorded along
with any observations as to sludge cake or precoat condition.  Since
in some cases much difficulty was encountered in obtaining a smooth
cut, each cut was rated on an arbitrary scale of smooth, slight gouging
and gouging.  When the optimum combination of the four variables for
a sludge was found, the sludge cake formed by those variables and the
precoat cut away with it were analyzed for solids content on the Ohaus
determination moisture balance.
Results

The results obtained with precoat vacuum filtration were generally good
for Edgell, Shannopin and Banning sludges and rather poor for Norton
sludge.

Precoat vacuum filtration was not found to be feasible for Norton sludge
as it was not possible to obtain a smooth cut.  The Norton sludge would
often crack the precoat and would always gouge it with the result that
on successive cuts the gouged portion of the precoat face would not be
cleaned of sludge.  Various precoats were tried, the drying time was
reduced to as little as one second, and both flocculants and body feed
were added in an attempt to eliminate the gouging, but with little
success.  It appeared as though the Norton sludge attached itself
unusually well to the precoat during filtration and as the sludge cake
shrunk during drying, pieces of precoat were pulled away from the
precoat cake.

Precoat vacuum filtration was found to be feasible for Edgell, Shannopin,
and Banning sludges.  Smooth cuts were obtained and in general it was

                                  74

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found that these three sludges would be suitable  for dewatering by
precoat vacuum filtration.

The results of the precoat filter leaf tests are  summarized in Table 17.
The best cycle time for all three sludges was  20  seconds filtration,
15 seconds drying and 10 seconds cutting.  This means a total drum
speed of 45 seconds per revolution which is generally considered to be
the fastest practical drum speed.  A fast drum speed was necessary for
efficient operation due to the rapid increase  in  cake resistance during
filtration shown by a sharp decrease in filtrate  flow rate with
time.  In addition a quick formation of cracks in the filter cake
during drying was observed which means that only  a short drying may be
used since the cake must be removed before it  cracks.  When a short fil-
tration time is indicated it could be achieved by a low submergence;
however, since this would increase the drying  time another solution had
to be found.  The only other mechanism available  to reduce filtration
time was drum speed and therefore a fast drum  speed was used to provide
a short filtration time and a short drying time.

The best precoat was generally Celite 501 although Hyflo Super-Gel
proved best in two cases.  These are both "fairly tight" precoats
(capable of retaining fine particles) as would be expected since the
sludge particles were small in size.

In the absence of detailed cost figures, as would be generated by a
pilot plant operation, it was felt that the most  realistic approach to
the problem of precoat usage versus filtrate recovery rates was to max-
imize filtrate recovery rates.  Using this criteria the optimum cut
was determined to be either 4 or 5 mils per minute for all sludges
tested with or without flocculants.

The highest filtrate recovery rates without a  flocculant were obtained
with Banning sludge which has the lowest solids content of the three
sludges which were found to be suitable for dewatering by precoat
vacuum filtration.  The lowest recovery rates  were obtained with
Edgell sludge which has the highest solids content.  The only un-
expected development in recovery rates was the high recovery rate of
Shannopin sludge with flocculants.  The average recovery rate of floc-
culated Shannopin sludge was slightly higher than that for flocculated
Edgell sludge.

The highest cake solids was obtained with Edgell  sludge both with and
without flocculant.  In all cases the solids content of the filter
cakes dropped with the use of flocculants, apparently due to the for-
mation of a thicker (and therefore more difficult to dry) cake produced
by the higher filtration rates.  A strong inverse relationship may be
noticed between filtration rates and cake solids  content.
                                   75

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                       Table 17




Optimum Conditions for Rotary Precoat Vacuum Filtration
Sludge
Shannopin
Shannopin
Banning
Banning
Edgell
Edgell
Flocculant
None
Nalcolyte 673
None
Coagulant 2350
None
Hercofloc 831
Cycle Knife
Time Advance
Filter/Dry/Cut Rate
(seconds) Precoat (mils/min)
20/15/10
20/15/10
20/15/10
20/15/10
20/15/10
20/15/10
Hyflo Super-Gel
Celite 501
Celite 501
Hyflo Super-Cel
Celite 501
Celite 501
5
4
5
4
4
5
Cake
Sludge Solids
Dewatered Content
(gal/f t^/min) (percent)
0.294
0.550
0.472
0.527
0.223
0.353
22.9
11.4
17.2
15.5
35.1
30.0

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The filtrate produced, as is typical with a precoat, was of excellent
clarity.  The filtrate from rotary precoat vacuum filtration could be
discharged into a stream without any further treatment.
                          Pressure Filtration

General

Pressure filtration is a process in which  the slurry to be dewatered
is forced into the filter press under high pressure and a porous media
in the press retains  the solids while allowing the liquid to pass.
A filter press generally consists of a series of chambers with plates
on either side.  The  plates are covered with a suitable filtering media
and have a drainage surface pattern of grooves, cones, diamonds, or
other forms through which the  filtrate may pass to the discharge line.
The chambers are formed by either recessing the plates or placing
distance spacer frames between them.  The  plates and frames are closed
together with sufficient pressure, normally applied either hydraulically
or by powered screws, to seal  the faces and prevent leakage.

After the slurry enters the chamber under  pressure and the filtrate
passes through the filter media and is discharged, the press is opened
and the cake removed.
 Test  Apparatus  - Description

 The bench scale experiments were performed with  a  D. R. Sperry and
 Company stainless steel 3-5/8 inch laboratory filter press, as shown
 in Figure 18.   The press was designed to duplicate the operation  of
 one-half of a  filter press cell,  The filter media was placed over the
 plate at the bottom of the unit, the sludge  poured into the chamber
 above the filter media, the upper plate with gasket added  and the screw
 tightened to prevent leakage.  The pressure  for  filtration was supplied
 by air from a  tank of compressed air.
 Procedure

 Initial tests performed by D. R. Sperry and Company and later confirmed
 by this work showed that a precoat would be necessary for the efficient
 operation of the filter press when dewatering acid mine drainage sludge.
 The use of a precoat eliminates the need to recycle part of the filtrate,
 improves filtrate clarity and eases cake discharge.

 Pressure filtration tests were initiated by precoating the pressure
 filter.  This operation was done by adding enough of a 2 percent precoat


                                   77

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Figure  18-PRESSURE  FILTRATION APPARATUS
                    78

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slurry (by weight) to the filter  to  form  a  cake  approximately  1/8  inch
thick as this size precoat was  found to be  the thinnest  precoat which
would not be eroded when the  sludge  was added to the  pressure  filter
chamber.  Pressure was applied  to the precoat slurry  and the slurry
filtered to dryness.  Next a  measured amount of  sludge was  carefully
added to the pressure filter  so as not to disturb the precoat,
pressure was applied, the time  recorded and all  the filtrate produced
was collected in graduated cylinders. The  amount of  filtrate  collected
in the graduated cylinders was  recorded at  intervals.

As the tests conducted were of  a  fairly long duration, it was  necessary
to periodically release the pressure, open  the unit and  add a measured
amount of additional sludge.  The fresh sludge was always added before
the level of the sludge in the  filter dropped below the  top of the sludge
cake so as not to disrupt the continuity  of the  test.

A test was near completion when either one  of two conditions were  met:
(1) the pressure filter chamber filled with sludge, (2)  a drop or
leveling off of filtrate recovery rate occurred.

When either of the conditions were met the  pressure was  continued  until
the filter cake cracked.  After the  cake  cracked, air was allowed  to
flow through the cake in order  to increase  cake  dryness.  At the end
of each test the cake was carefully  removed from the  chamber and the
precoat scraped off.  The cake  was then measured for  thickness and
weighed.

Pressure variation, the use of  flocculants  and the length of the
filter run were the variables studied in  these pressure  filtration
tests.  It was learned from talks with Calvin Mohr, a representative
of D. R. Sperry and Company and an expert in the area of pressure
filtration, that filtration rates could drop off at high pressures.
This was due either to blinding of the precoat and/or to greater cake
compression which caused a decrease  in cake permeability and porosity.

In order to select the optimum  operating  conditions,  various pressures
were examined and three pressures were chosen.   The lower pressure,
60 psig, was the lowest pressure  that could produce sufficiently high
filtration rates to dewater the large volumes of sludge  created by acid
mine drainage treatment.  The highest pressure,  100 psig, was  the
highest pressure at which the laboratory  filter  press could be safely
operated.  The third pressure,  80 psig, represented an intermediate
pressure between the high and low pressures.

The second important variable investigated  was the use of a flocculant
to increase filtration rates.  The most efficient flocculant at its
optimum concentration for each  sludge, as determined  by  Buchner funnel
tests, was examined.  Each sludge was investigated with  and without
                                   79

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flocculants and the results compared.

During each test, the amounts of sludge added to the filter and the
amounts of filtrate recovered with increasing time were recorded.
As the cake increased in thickness, the resistance of the cake to
the passage of filtrate increased, eventually reaching a point at which
the time required to remove the cake would be more than offset by the
increased filtration rates obtained after its removal.  Establishment
of this point gave the optimum length (time) of a filter run.  Having
established the time of a filter run and the volume of sludge dewatered,
it was possible to use this data to determine the size of a filter
press necessary to dewater a given volume of sludge in a given length
of time.  At the end of each test, the cake was weighed and measured.
From this data, the volume of cake produced by a given volume of
sludge, under the conditions of the test in question, and the density
(weight per unit volume) of that cake were calculated.  The volume
of cake produced must be known for the proper selection of a pressure
unit in order to allow sufficiently large chambers to contain the
cake.  The density of the cake was used to calculate the weight which
the unit and its supporting foundation must bear.  The percent solids
of the cake was determined in order to evaluate the dewatering effici-
ency of the variables under study and to allow for a better comparison
of the various dewatering methods.
Results

Pressure filtration was found to be a feasible dewatering system foi
all four sludges.  The results of tests performed with and without
flocculants added to the four representative sludges at a low pressure
(5 psig) are shown in Table 18.  This table shows that the addition of
flocculants gave a large increase in filtrate recovered in one
minute with the final percent solids of the cake being slightly lowered.

However, after talks with and testing by D. R. Sperry and Company it
was decided that sufficiently high rates could be obtained without the
use of flocculants.  Also pressures lower than 60 psig should not be
considered since the main advantage of pressure filtration is high fil-
tration rates per unit of filter surface area which requires high
pressures.  Low pressures were inefficient from a cost standpoint.
Preliminary tests by D. R. Sperry and Company indicated that a pre-
coat was necessary due to the fine particle content of the sludge.
Recommendations were made that Johns-Manville Hyflo Super-Gel precoat
be used along with Sperry No. 3 Cotton Twill Filter Cloth with Sperry
No. 11 Filter Paper placed over it.  Therefore these filter media
were used in all pressure filtration tests.

Results of long duration tests are shown in Figures 19 through 22
                                  80

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00
                                          Table 18




                            Pressure Filtration Tests at 5.0 psig
Sludge
Norton
Norton
Edgell
Edgell
Banning
Banning
Shannopin
Shannopin
Flocculant
None
Decolyte 940
None
Hercofloc 831
None
Coagulant 2350
None
Nalcolyte 673
Filtrate
In One
Min.
(mis)
72
104
29
32
71
145
20
27
Increase
In Filtrate
Recovered
With Floe.
(percent)

44.4

10.3

104.2

35.0
Final
Solids
(percent)
26.3
25.8
17.2
16.0
10.8
8.8
17.7
16.4

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             ZOOOr
             1500
      TOTAL
      FILTRATE
QO
VOLUME-
      MLS.
             1000
              500
JOO PSI
  O PSI
-60 PS/
                                 2       3
                                 TIME-HOURS
                 Figure 19 - PRESSURE FILTRATION TESTS OF SLUDGE
                          FROM SHANNOPIN  TREATMENT PLANT

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             3000
oo
OJ
             2500
             2000

            TOTAL
           FILTRATE
             1500
            VOLUME
                                  2       3       4
                                      TIME-HOURS
             Figure20-PRESSURE FILTRATION TESTS OF SLUDGE FROM BANNING
                     TREATMENT PLANT

-------
            2000
00
            1500

      TOTAL

      FILTRATE
            1000
      VOLUME-
      MLS.
             500
                                         100 PSI

                                            PSI
-60 PSI
                0123456

                                   TIME-HOURS

       Figure 21 - PRESSURE  FILTRATION TEST OF SLUDGE  FROM NORTON
                TREATMENT PLANT

-------
oo
Ul
             2000
             1500
      TOTAL

      FILTRATE
      VOLUME-
      MLS.
              1000
              500
                 0
>80 PSI
        -60 PSI
         100 PSI
       3       4

    TIME-HOURS
         Figure 22- PRESSURE FILTRATION  TESTS  OF SLUDGE FROM EDGELL

                  TREATMENT  PLANT

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and in Table 19.  All four sludges were tested at 60, 80 and 100 psig.

Since Shannopin sludge showed nearly the same filtration rates at
all three pressures, 60 psig was selected as the best operating
pressure.
                                           i
For Banning sludge 100 psig was selected as the best operating pres-
sure due to the large increase in filtration rates at this pressure
as compared to filtration rates at 60 and 80 psig.  100 psig was
the only pressure at which cake data was taken for Banning sludge.
The cake data is presented in Table 19.

Norton sludge produced a very thick cake and had nearly the same
filtration rates at all three pressures.  Therefore 60 psig was
selected as the most economical operating pressure.  This is the
only pressure reported for Norton in Table 19.

With Edgell sludge the filtration rate dropped off at 100 psig due to
either blinding of the precoat and/or to greater cake compaction
which caused a decrease in cake permeability and porosity.  The best
operating pressure for Edgell sludge appeared to be 60 psig, as only
a relatively small increase in filtrate recovery was realized by
increasing the pressure to 80 psig.

In all tests performed a clear filtrate was recovered.

                v       ^
                        Porous Bed Filtration
                *?
General

Drying beds utilizing sand, coal, or other filtering media have been
used to successfully dewater sewage and industrial sludges.  Drying
beds are generally constructed to hold a graded (a gradual change in
particle size in a vertical direction) filtering material.  A bed
of coarse gravel is frequently laid over an under drain and then
followed with a finer material.  The finest material (placed on top
of the bed) must be of sufficiently small particle size that the voids
between particles are smaller than the particles of the sludge being
filtered.  When sludge is introduced onto the surface of the sludge
drying bed, drainage immediately takes place as the filtrate percolates
through the filter media and the solid particles are trapped on the
surface.  Following the initial drainage stage, evaporation then
takes place.  As the sludge becomes dryer, a point of dryness is
reached when the sludge can be lifted from the surface of the drying bed.
Depending upon the type of sludge being dewatered, conditioning agents
can be added that accelerate the drainage cycle.  To prevent rain from
entering the drying bed, a covering can be placed over it.
                                  86

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                                                 Table 19




                                       Pressure Filtration Cake Data
00
Sludge
Used
Norton
Edgell
Edgell
Edgell
Banning
Shannopin
Shannopin
Shannopin
Pressure
(Ibs/sq. in.)
60
60
80
100
100
60
80
100
Thickness
of
Final Cake
(inches)
7.5000
0.5000
0.3750
0.5625
0.8750
2.3750
2.7500
2.8750
Filtration Time
To Produce
Cake
(minutes)
179
198
138
175
219
170
180
200
Final
Solids Of
Cake
(percent)
20.8
26.2
26.0
26.0
11.8
8.7
12.0
10.9
     All sludges were air blown for 5 minutes after break.

-------
Test Apparatus - Description

The test apparatus used for the drying bed experiments was construc-
ted of clear plastic and is shown in Figure 23.  Essentially this
apparatus was a tapered tank with a valve fitted at one end.

Preliminary tests were performed to find the smallest filter particle
size that would completely stop the mine drainage sludge from penetrating
the surface.  It was found that 40 x 60 mesh wet screened sand or coal
could serve as the top layer of the filter bed.

Coal was the first filter media examined.  A wet screened 1.5 inch
thick bed of 1 x 1/4 inch bone coal was laid down followed by 1.5
inches of 1/4 inch thick bone coal.  The lower layer of coal, placed
atop the bone coal, was 10 x 20 mesh, the second 20 x 40 mesh and
the top 40 x 60 mesh.  This layering of progressively smaller size
fractions formed an approximately 6 inch thick filter bed grading from
coarse at the bottom to fine at the top.

Following the filtration tests using coal as the filter media, high
quartz silica sand was examined.  The base of the vessel was covered
by 1.5 inches of screened 1 x 1/4 inch gravel followed by a 1.5 inch
layer of 1/4 inch x 10 mesh gravel.  Three one inch layers of sand
were then deposited on the gravel base.  The lower layer was 10 x 20
mesh, the middle layer was 20 x 40 mesh and the top layer was 40 x
60 mesh.  All mesh sizes given are U. 8. Standard sieve series.  The
total filter thickness was 6 inches which duplicated the thickness
and grading of the coal filter.  A glass tube was inserted into the
filter media at one end of the vessel to vent the filter system and
allow the filtrate collected at the bottom of the filter to drain
freely.  The effective filter area in the test vessel was approxi-
mately 4 square feet.
Procedure

A test was initiated by first filling the vessel with tap water so as
to moisten and protect the bed from erosion.  The sludge was then
allowed to flow from a large container by gravity onto a splash pan
located in the center of the filter bed.  The splash pan was introduced
as part of the apparatus to minimize bed surface disturbances as the
sludge was introduced.  As soon as sufficient sludge was on the bed to
prevent erosion the splash pan was removed.

Two tests were conducted on the coal bed filter.  In each test, a
40,000 ml sample of Edgell sludge containing 6 percent solids was
introduced into the vessel.  One test was conducted with sludge that
had been conditioned with 111 ppm Hercofloc (shown to be the best
flocculant for this sludge from the conditioning studies) while the

                                  88

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                     (a)
                    (b)
Figure 23- POROUS  BED FILTRATION  APPARATUS
         (a) TOP 8 FRONT  VIEW  (b)SIDE VIEW
                  89

-------
second test was conducted with unconditioned sludge.

A series of three tests was conducted using sand as a filter media.
The first test was performed with a 40,000 ml sample of 6 percent
solids Edgell sludge.  A second test was conducted using a 2.3 per-
cent solids Edgell sludge and a third test was performed using 2.7
percent solids Edgell sludge conditioned with 111 ppro Hercofloc.

During each test the clarity of the filtrate was observed and a per-
cent solids determination of the sludge cake was made at various
times following the introduction of the sludge into the drying vessel,
Results

From the preliminary tests conducted, porous bed filtration appeared to
be a technically feasible method of dewatering coal mine drainage sludge.

Data collected from the sand bed and coal bed drying tests is presented
in Table 20.  Using an arbitrary figure of 20 percent solids of the dried
cake as a criteria for liftable conditions, it appears from Figure 24
that there is a linear relationship between solids loading (weight of
solids per unit of surface area) and drying time.

The drying tests conducted using flocculant conditioned sludges
indicated that conditioning did not significantly improve sludge de-
waterability in this case.  The flocculants used were selected on the
basis of increased filtration rates and would be expected to speed
up the filtration rate (or draining) of the sludge.  However, the
filtration phase of porous bed drying is short compared to the
evaporation phase and even a relatively large decrease in the time
required for the filtration phase has only a slight effect on total
drying time.

It was noted that shortly after the drainage or filtration phase
was completed, cracking was observed in the cake.  This was due
primarily to shrinkage of the sludge cake during drying and is
similar to "mud cracks".

From the point of view of increasing the rate of drying, cake cracking
appears to hold two advantages.  First, as the number of cracks in-
crease, the total surface area of the sludge cake exposed to atmospheric
conditions increases.  Secondly, if drying beds were used out of doors,
rain water would be able, at least in part, to move through the cake
surface cracks and filter bed rather than sit on the surface of the
cake., There does not appear to be any advantage between either coal
or sand as a filter media.  No significant difference in drying time
                                  90

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vo
I-1
                                                   Table 20


                                          Data From Drying Bed Tests

Coal Bed
Coal Bed
Sand Bed
Sand Bed
Sand Bed
Test
No.
1
2
3
4
5
Solids
Loading
(lb/sq. ft.)
1.190*
1.026
1.010
0.403
0.0379*
Temperature
(°F) + 5
75
75
75
75
75
Drying
Time**
(Days)
26
25
24
13
12
Volume of Sludge
Dewatered (ml)
40,000
35,000
40,000
40,000
40,000
       Treated with 111 ppm Hereofloc 831 flocculant,
     **
       Time to achieve 20 percent solids content in cake.

-------
  SOLIDS

  LOADING I

  LBS/FT
vO
NJ
         10
12
14
 16       18      20
DRYING TIME - DAYS
22
24
26
  Figure 24 - RELATIONSHIP OF DRYING TIME AND  SOLIDS LOADING FOR SLUDGE FROM
             EDGELL TREATMENT PLANT

-------
or filtrate quality was observed.

The quality of the filtrate  from both  the  coal  filter and sand
filter was quite high as indicated by  an absence of non-filterable
solids in the filtrate.
                      Thermal  Spray  Drying

General

Thermal spray drying  is  a  technique  that uses  contact with hot gases
to remove moisture  from  solids.   It  involves the  following operations:
(1) atomizing the sludge;  (2)  combining  hot gases with atomized sludge
droplets;  (3) collecting and separating  the dried product and the
air.

Since spray drying  operates  essentially  by evaporating the water
from the sludge directly,  the  single most important cost variable is
the amount of water to be  removed from the sludge or the evaporative
load.  The costs of this system,  for a given material, tend to vary
inversely with the  water content  of  the  feed sludge.  In order to
minimize costs, a spray  drying apparatus, especially for a low solids
sludge, would most  likely  be preceded by a mechanical sludge thickening
operation.


Test Apparatus - Description

Spray drying tests  were  conducted using  a Bowen Conical Laboratory
Spray Dryer, which  is shown  diagramatically in Figure 25.

Air for drying was  heated  by natural gas burners  placed under a hood
after which the air passed into  the  drying chamber.

The conical drying  chamber was approximately 6 feet high, 30 inches in
diameter at its widest point and  constructed of type 316 stainless
steel.  The drying  chamber had an open,  uncluttered interior and an
included angle of 40° to prevent  an  accumulation  of the dried product
which would be detrimental to  efficiency by interfering with smooth
passage of air and  dried product  from the chamber.

The cyclone collector was  conical in shape and had roughly one-fourth
the volume of the drying chamber. The dried product was discharged
from the bottom of  the collector  and the air from the top.
Procedure

Each sludge was atomized  through a spray nozzle at the top  of  the

                                   93

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                SLUDGE FED TO  ATOMIZER
                    BY MOYNO PUMP
     THERMOMETER
       L
 AIR
HEATER
      A A A
     HEATED BY
    GAS  BURNERS
i
         -ATOMIZER
         INSPECTION
            PORT
          CT
                    THERMOMETER
                               /
                        CYCLONE
                       COLLECTOR
                                                             GLASS
                                                           PRODUCT JAR
Figure 25- SPRAY DRYING APPARATUS  AFTER  BOWEN ENGINEERING
                                                          (13)

-------
conical chamber.  Sludge was delivered  to  the atomizer by a Moyno pump.
Several types of atomizers are available;  however,  the standard model
with six air holes surrounding a  central hole through which the sludge
was pumped, proved adequate for mine drainage sludge.  The seven hole
nozzle was covered with a rounded cap with a single hole in the center
through which the atomized sludge was sprayed into  the drying chamber.

Hot air was drawn into the conical drying  chamber near the atomizing
nozzle by a blower located on the hot air  exhaust portion of the
apparatus.  This same blower pulls the  air (unheated) used to atomize
the sludge through the spray nozzle.  The  hot air inlet is so positioned
as to cause the air  to travel through the  drying chamber in a spiral
configuration.  This spiraling effect increases retention time of
the hot air and sludge in the chamber and  promotes  good mixing.
Hot air which is now thoroughly mixed with the finely divided dry sludge
particles passes out of  the bottom of the  chamber,  through duct work,
and into a cyclone collector where the  sludge particles are removed.
The hot air then passes  through the blower and is exhausted.  If it
should prove necessary,  a wet scrubber  could be installed at this point
to remove any remaining  sludge particles or perhaps a second cyclone
collector could be utilized.

In the laboratory tests  performed at Bowen Engineering, Inc., the
temperature of the heated air entering  the conical  chamber was held
at 1000°F  (the maximum possible with the equipment  used).  The
temperature of the air leaving the chamber was modified by varying
the flow rate of the sludges.  Laboratory  tests established the
lowest exit temperature  (or highest flow rate) which would allow the
sludge to dry sufficiently so that it would not stick to the chamber
walls or the duct work and clog the equipment.  This lowest exit
temperature represented  the most  efficient use of heat possible in
thermal spray drying and therefore the  most economical operating condi-
tions.  Data collected on the spray drying tests is summarized in
Table 21.

The four sludges were tested at a solids content different from that
employed in the other dewatering  systems  (Table 21).  The solids contents
used in the spray drying tests were chosen by Bowen Engineering, Inc.
to allow them to better  evaluate  the spray drying characteristics of
the sludges.
 Results

 All four sludges could be reduced to a very fine powder  of  light
 brown to reddish brown color with a solids  content of  about 90 per-
 cent.  The dewatered solids content was higher  than that produced by
 any other method under consideration.   Whether  or not  spray drying
 would be an acceptable method  of  dewatering sludge is  largely a
 matter of economics.

                                   95

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                                   Table 21


                          Test Data From Spray Drying
       Run No.               1


FEED CONDITIONS;


Mine Drainage Sludge       Norton


Wt. % Solids - Typical     8.0


Wt. % Solids Used in Test  8.5


Spec. Gravity              1.05
                             £

Temperature °F             70


Feed Rate Mls/Min          560-600


Total Feed, Mis            1,800
OPERATING CONDITIONS;


Inlet Temp. °F


Outlet Temp. °F


Type Heat


Atomizer Type


Atomizing Force,
   Air Press, PSIG
Shannopin
2.1
11.0
1.08
70
590-630
4,100
970-985
325
Banning
0.5
9.5
1.08
70
900-961
4,050
990
265-280
Edgell
2.7
1.0
1.00
70
650-700
7,400
990-1,000
305-315
995


340


Direct Gas Used For All


Two Fluid Nozzle Used For All
95
100
95
                                             95

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                                        Table 21 (Continued)
•-o
•vj
                Run No.


         OPERATING CONDITIONS:
(Continued)
Chamber Conditions
MATERIAL BALANCE:
Cyclone Collector, Cms.
Chamber Wall, Gms.
Total Collected, Gms.
Total Solids Fed, Gms.
% Recovery, Wet Basis

Light
Static
Accumula-
tion
105
25
130
160.5
81.0

Damp Spot
Upper cone
260
100
360
486
74.1

Wet Spot
on Cone
and Wall
145
280
425
415
100+

Wet
and
30
nil
30
74
40.6

Wall
Cone






-------
                            jtentrifugation

General

Centrifugation is a method of separating materials of different densi-
ties by the use of centrifugal force.  There are many types of commer-
cial centrifuges but all consist of a feed system which delivers the
material to be dewatered, a revolving basket or bowl to collect the
solid particles, a discharge line and a system for removing the built
up solids.

Material to be dewatered is fed into the bowl or basket and during
the operation solids are forced away from the axis of rotation of
the bowl and deposited on the wall, while the centrate fills the bowl.
When the bowl is filled to capacity, the effluent is discharged,
generally over the sides of the bowl, and exits through a discharge
line.

The solid material is then removed by an automatic scraper blade or
some other device designed to remove the material.

A solid bowl centrifuge of the type studied in this work has two
methods of solids removal.  The first method, skimming,  is performed
whenever the clarity of the effluent drops below an acceptable level.
Skimming removes the softer, less compact sludge solids.  The second
method of solids removal involves scraping the harder, more compact
sludge solids collected along the circumference of the bowl.  These
solids are removed when they have accumulated to the point that they
have reduced the capacity of the bowl and made the time between
skimming operations prohibitively short.
Test Apparatus - Description

The bench scale experiments were performed with a 14" diameter basket
Fletcher Mark III centrifuge of the solid bowl type which operates
at variable speeds and is electrically powered.  The machine was rented
from Sharpies-Stokes Division of Pennwalt Corporation and is shown in
Figure 26.  This centrifuge was designed to duplicate a large indus-
trial type centrifuge.

A gravitational feed system was used to supply sludge to the centri-
fuge.  The sludge was siphoned from an elevated 55 gallon drum through
a 1/2 inch pipe equipped with a globe type valve into a secondary
20 gallon cylindrical plastic container.  The sludge was discharged
from the secondary container into the centrifuge.  Various flow rates
to the centrifuge were maintained by the use of a predetermined piezo-
metric head within the secondary container for each flow rate.  The
                                  98

-------
Figure  26- CENTRIFUGATION APPARATUS
                  99

-------
sludge was kept thoroughly mixed by the use of a 1/2 horsepower
electrically powered Lightnin mixer.

The solid bowl, which was cylindrical shaped, was 14 inches in diameter
by 6 inches in height and had a 1 7/8 inch lip ring around the top.
A truncated cone approximately 6 inches in diameter at the base and
2 inches in diameter at the top by 4 inches in height was bolted to
three mounts at the bottom of the bowl.  These mounts were approximate-
ly 1/4 inch in height and one inch square; therefore three slots 1/4  ,
inch in height were situated under the conical section.  Sludge entered
the centrifuge through a 1 inch diameter pipe into the top of the
conical section and was dispersed uniformly under the bottom of the
cone; this assures flow throughout the bowl from bottom to top.  Cen-
trate flowed over the lip ring on the top of the bowl when the bowl's
capacity of 1.5 gallons was reached.

The discharge line was a 2 inch hose running from the bottom of the
centrifuge to the drain.

The sludge skimmer pipe was 3/8 inch diameter and passed through the
lid of the centrifuge with one end of the pipe (entrance)  inside the
bowl and pointing in the opposite direction to the bowls rotation.
The exit end of the skimmer protruded vertically from the top
of the centrifuge and was bent 90° to the front of the machine.  A
rachet arrangement was used to advance the skimmer manually from the
center of the bowl towards the side while the bowl was in rotational
operation.  Centrifugal force in the bowl forced the thick sludge
out of the pipe when the skimmer was activated.
Procedure

Sludge to be used for each test was put into a 55 gallon drum equipped
with a Lightnin mixer and a siphon pipe.  The mixer was started
and it continued to run for the duration of the test to keep the sludge
thoroughly mixed.  The siphon was started and sludge was added to the
secondary plastic container and the desired predetermined piezometric
head for each particular run was obtained.  The flow rate was checked
by measuring the amount of slurry which flowed in one minute.

The variable speed centrifuge was activated and stabilized at a
rotational speed of 2750 revolutions per minute.  This speed vras re-
commended by the manufacturers of the Sharpies-Fletcher centrifuge,
and was based on acid mine drainage sludge tests performed earlier
using a limestone sludge.

At the beginning of each test the time was recorded and samples of
the effluent discharged were taken at one minute intervals, starting
                                 100

-------
with the initial discharge  and ending  with the  termination of a  test.
As the test progressed  the  howl accumulated more  and more sludge which
reduced its effective volume.   The  reduction of the bowl's effective
volJime reduced the retention  time of  the  slurry which  reduced the
effectiveness of solids  removal.  The  centrifuge  operation was con-
timied until the effluent discharged had  approximately the same  per-
cent solids concentration as  the feed  going into  the howl; this  is
done hy comparing the clarity  of a  bottle of sludge feed to a bottle
of effluent.

Sludge feed was then stopped,  but the  operation of the centrifuge
continued.  The effluent which remained in the bowl was skimmed  by
advancing the skimmer pipe  into the bowl  until the liquid-solid  inter-
face was reached.  At this  point the distance from the skimmer to the
outer circumference of  the  bowl was recorded and  was a direct measure of
the amount of sludge in  the bowl.   Most of the sludge  which remained was
skimmed off; however, a  very compact sludge on the side of the bowl
cannot be removed by the skimmer for if contact should occur between
the skimmer pipe and the bowl  damage would occur.  The centrifuge was
then stopped.  The compact  cake, called the bowl  cake  or bowl solids,
which remained was measured for thickness at the  top,  middle and bottom
of the bowl and recorded and  the sludge scraped from the side of the
bowl.

The most important parameters  of the  test were centrifugal force,
(speed-diameter) feed rate  and characteristics of the  sludge.  Tests
were run at flow rates  of 1/2, 1, 1-1/2,  2,  2-1/2 and  3 gallons  per
minute for non-flocculated  sludges. If the tests which were per-
formed at lower feed rates  lasted 5 minutes or less, further tests
were not made at increased  feed rates  as, according to the manufac-
turers, shorter runs would  be  impractical.  Each  sludge was also
tested at 1/2 gallon per minute with  the  correct  concentration of
flocculant added as determined earlier in vacuum  filtration tests.

Samples of feed, effluent discharged  from beginning to end of run
at selected intervals,  skimmer sludge  and sludge  deposited on the
wall of the bowl were submitted for percent solids analysis.  Due
to the length of each run many effluent discharge samples were col-
lected and several were discarded as  they were similar in clarity.
Results

Centrifugation was  found to  be a feasible dewatering  system  for
Norton, Shannopin and  Banning sludges.   Edgell sludge was  not  tested
due to difficulties encountered in obtaining this  sludge in  suffi-
ciently large quantities.  The Edgell settling lagoon is located  far
from  the nearest  road  and samples must be carried  out by hand, making
the collection of several hundred gallons of sludge difficult.
                                  101

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As would be expected all sludges show a decrease in the time the
centrifuge can be operated as the feed rate of sludge increases or
as the solids content of the feed sludge increases.  This is due
to the increase in sludge volume deposited in the bowl with tine.
The more rapidly the sludge accumulates, the less the effective
volume of the bowl and the less effective its removal of solids.

Figure 27 shows the results of the tests on Shannopin sludge.  The
length of time the centrifuge can be operated before skimming de-
creases with increasing feed rates as shown by Curves 1 through 3.
For Curves 4 and 5 the feed rate has reached the point that centrate
clarity drops to an unacceptable level (below 90 percent recovery)
in less than a minute.  Curve 3 appears to be a good combination
of feed rate and length of run and would represent the feed rate at
which the greatest volume of sludge could be dewatered per unit of
time.

Curve 6 shows the effect of a flocculant on Shannopin sludge.  Since
Curve 6 differs very little from Curve 1 (the same feed rate) it
would appear that little advantage would be gained in applying this
flocculant.

Figure 28 shows the results of centrifugation tests on Banning sludge.
Banning sludge behaved similarly to the Shannopin sludge with Curve
3 again* representing the maximum practical feed rate.  The use of a
flocculant in this case increased the length of time the machine
could be operated (Curve 1) before skimming and would increase the
amount of sludge which could be dewatered by the machine.

Figures 29 and 30 are for Norton sludge.  Figure 29 shows the
rate at which the length of a run decreases as the solids content
of the feed sludge increases.  Curve 4 represents the test made
using a flocculant.  Curve 4 drops before Curve 2,  a test of the
same flow rate and an even higher solids content, thvis the flocculant
decreased the capacity of the machine.  Figure 30 shows the results
of increasing the feed rate of Norton sludge.   Curve 2 represents
the maximum feed rate under these conditions.   Curves 1 and 4 may
be compared to determine the effect of increasing the feed solids
content of Norton sludge at a flow rate of 1 gpm.

Tables 22 through 24 present the solids content of the dewatered
sludge.  Norton sludge dewatered by centrifugation showed the highest
solids content and Banning sludge the lowest.
               Summary of Results on Dewatering Attempts

It was found that it was technically feasible to dewater all four
sludges by any of the six dewatering systems studied with the ex-
                                 102

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       IOO
        80
        60

EFFICIENCY

OF SOLIDS
        40
REMOVAL-
PERCENT
        20
CURVE
  I
  2
  3
  4
  5
  —fc^T*
FEED RATE
  GPM
                        FEED SOLIDS
      0.5
      I.O
      1.5
      2.0
      2.5
      0.5
Wco/yte  673 Added
                2.27
                2.08
                2.09
                2.04
                2.24
                1.85
    i
                                                        i
                             8       12
                                TIME-MINUTES
   16
                        20
                        24
  Figure 27 - CENTRIFUGATION TESTS OF SLUDGE FROM SHANNOPIN TREATMENT
            PLANT.

-------
        100 r
         80
         60 -
EFFICIENCY
OF SOLIDS
        40
REMOVAL-
PERCENT
         20
                            8
     CURVE
       I*
       2
       3
       4
       5
       6
FEED RATE  FEED SOLIDS
   GPM         %
                                      I
         I
12        16
 TIME-MINUTES
              0.99
              0.64
              0.68
              0.69
              0.72
              0.73
    20V  25   30  35  40
     Coagulant 235O Added.
 Figure 28-CENTRIFUGATION TESTS OF SLUDGE  FROM BANNING TREATMENT PLANT.

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           100
           80
   EFFICIENCY
   OF SOLIDS
           60
   REMOVAL-
   PERCENT
o
Ui
            40
            20
CURVE

  I
  2
  3
  4
          FEED RATE
             GPM
             0.5
             0.5
             0.5
             0.5
        FEED SOLIDS
            %

           1.54
           5.52
          10.05
           3.77
                                                            *Decolyte940 Added
                                              _L
J_
_L
                      _L
J_
                                8    10   12   14   16    18   20  22   24  26   28   30
                                            TIME-MINUTES
      Figure 29 - CENTRIFUGATION TESTS OF SLUDGE FROM NORTON TREATMENT PLANT.

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        100
        80
EFFICIENCY

OF SOLIDS

REMOVAL-

PERCENT
60
         40
        20
                             8
                             CURVE

                               I
                               2
                               3
                               4
FEED RATE FEED SOLIDS
  GPM      %
   1.0
   1.5
   2.0
   1.0
2.09
2.48
2.73
6.12
                             12        16
                             TIME-MINUTES
        20
     24
  Figure 30- CENTRIFUGATION TESTS OF SLUDGE FROM NORTON TREATMENT
             PLANT.

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                                       Table 22

                                 Centrifugation Tests
                           Shannopin Treatment Plant Sludge
Figure
Number
27
27
27
27
27
27
Curve
Number
1
2
3
4
5
6*
Feed Solids
(percent)
2.27
2.08
2.09
2.04
2.24
1.85
Flow Rate
(gpro)
0.5
1.0
1.5
2.0
2.5
0.5
Bowl Solids
(percent)
33.4
33.6
32.5
36.9
35.4
26.6
Skimmer Solids
(percent)
11.0
8.8
9.0
8.0
7.7
13.8
Nalcolyte 673 added

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                                               Table 23


                                         Centrifugation Tests

                                     Banning Treatment Plant Sludge
o
00
Figure
Number
28
28
28
28
28
28
Curve
Number
2
3
4
5
6
1*
Feed Solids
(percent)
.64
.68
.69
.72
.73
.99
Flow Rate
(gpm)
0.5
1.5
2.0
2.5
3.0
0.5
Bowl Solids
(percent)
8.8
8.4
8.7
8.6
8.1
11.4
Skimmer Solids
(percent)
5.1
3.8
4.6
5.0
5.6
9.2
y-
       Coagulant 2350 added

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                                       Table 24

                                 Centrifugation Tests
                             Norton Treatment Plant Sludge
Figure
Number
29
29
| 29
29
30
30
30
30
Curve
Number
1
2
3
4*
1
2
3
9
Feed Solids
(percent)
1.54
5.52
10.05
3.77
2.09
2.48
2.73
6.12
Flow Rate
(gpm)
0.5
0.5
0.5
0.5
1.0
1.5
2.0
1.0
Bowl Solids
(percent)
41.3
53.7
64.1
63.0
44.9
50.5
55.8
51.8
Skimmer Solids
(percent)
12.9
19.3
17.5
22.1
11.6
13.5
12.8
19.2
Decolyte 940 added

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ception that precoat rotary vacuum filtration was found not to he
applicahle to Norton sludge.  Conventional rotary vacuum filtration
was technically feasible for all sludges, hut to be practical for use
on Shannopin, Edgell and Banning sludges additional thickening or
special equipment would be necessary.

Porous bed filtration and all systems utilizing a precoat produced
a filtrate of sufficient clarity to be discharged directly into a
stream.  Thermal spray drying produced only water vapor which could
be discharged directly into the atmosphere.  Both conventional rotary
vacuum filtration and centrifugation produced water of a relatively low
clarity and would require recycling to the clarifier.

No system showed a significant advantage in solids content of de-
watered sludge produced except for thermal spray drying.  The other
dewatering systems generally produced sludge cakes of from 10 to 30
percent solids while the thermal spray drying method produced dried
sludge containing over 90 percent solids.

Two systems, pressure filtration and porous bed filtation were
noticeably free of operational problems during bench scale testing.
However, the bench scale testing of porous bed filtration did not
include an evaluation of cake removal systems, a possible source of
difficulty.
                                 110

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                              SECTION VII

           ECONOMIC EVALUATION OF SLUDGE DEWATERING ATTEMPTS


The purpose of an economic evaluation of sludge dewatering systems
is to provide a relative cost comparison of the six dewatering
systems studied.  To estimate highly accurate cost figures for any
particular dewatering system, actual pilot plant scale tests, rather
than bench scale tests, should be performed.  The cost figures pre-
sented here are primarily intended to be used as guides for comparison
of systems in respect to each other.

In order to make a realistic economic evaluation of the various pro-
cesses, costs must be based on certain assumptions.  To facilitate the
best possible understanding of this analysis a complete list of the
assumptions is presented:

 1.  Straight line depreciation over complete life of equipment.

 2.  Location - Morgantown, West Virginia.

 3.  Time - Spring of 1972

 4.  Operation of equipment 24 hours per day, 365 days per year with
     excess size to facilitate periodic shut downs.

 5.  Maintenance assumed to be 6 percent of total capital cost.

 6.  Fuel:  $0.13 per gallon, #2 fuel oil, 130,800 BTU's per gallon.

 7.  Electricity:  $0.0175 per kilowatt hour.

 8.  Labor Cost:  $6.00 per hour, includes shift differentials, over-
     time premium, payroll overhead, supervision and fringe benefits.

 9.  Dewatering system to be constructed simultaneously x
-------
     watered was characterized as:

     Shannopin, 180,000 gallons/day at 2.1 percent non-filterable solids
     Banning, 360,000 gallons/day at 0.5 percent non-filterable solids
     Norton, 50,000 gallons/day at 8.0 percent non-filterable solids
     Edgell, 100,000 gallons/day at 2.7 percent non-filterable solids.

13.  Retention time required for all clarifiers assumed to be one hour.
     A list of factors not considered in the evaluation would include:

       1.  Miscellaneous supplies

       2.  Laboratory costs

       3.  Real estate taxes

       4.  Insurance                                                 !

       5.  Working capital

       6.  Land costs

       7.  Differentials in costs of transportation and disposal due
           to dryness of dewatered sludge

       8.  Plumbing and heating of building

Equipment specifications were determined after consultation with the
respective manufacturers using extrapolated data collected during ex-
perimentation.  Capital costs are totally on price quotations from the
manufacturers except for porous sand bed filtration costs which are
based upon a recent study by Barnard and Eckenfelder.(15)

Operational costs were based on correspondence with equipment manufac-
turers, material suppliers or local utilities.

As noted in the sludge dewatering section of this report, some of the
dewatering systems were evaluated with a flocculant added to the sludge.
The primary economic advantage obtained by the addition of a flocculant
would be to increase filtration rates which would increase the efficiency
of the dewatering unit.  If the efficiency of a unit could be suffi-
ciently increased, it would be possible to utilize a smaller unit
thereby reducing capital costs.

Results obtained by using a flocculant were generally favorable for
reducing equipment sizes.  However at the concentrations determined in
laboratory testing the savings in equipment would in all cases be off-
set in a very short time by the cost of the flocculant.  Flocculant
                                 112

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treatment of the sludges may have produced better economic results if
concentrations would have been based on  economic optimization rather
than maximization of filtration rates.

The effluents from centrifuging and conventional vacuum filtration
were felt to lack sufficient clarity for direct stream discharge and
therefore xrould require additional treatment.  The simplest and most
efficient method of accomplishing this would be to recycle all of
the effluent through a thickener clarifier.  However, in all cases,
the cost of the increased size clarifier required to handle the
additional liquids did not significantly alter the final relative
costs.
                    Conventional Vacuum Filtration

Evaluation of bench scale experiments proved that only the Norton
Treatment Plant sludge  (limestone sludge) possessed physical proper-
ties acceptable for dewatering by conventional; vacuum filtration.  This
held true for sludges treated with  flocculants as well as those un-
treated.  In all cases  tested, conventional vacuum filtration produced
a filtrate unacceptable for discharge directly into a stream.  There-
fore all filtrate must  be recycled  through the clarifier, from which
the overflow could be discharged into any nearby stream.

After correspondence with Mr. Lewis ArabiadD of Eimco Processing
Machinery Division, Envirotech Corporation, it was determined that
one 6 foot diameter by  6 foot face  drum filter with a belt discharge
would suffice for the assumed Norton dewatering system.  The cost
was estimated to be $3.40 per 1,000 gallons of sludge dewatered.
Adding this dewatering  system to an existing neutralization system would
increase total cost by  $0.01 per 1,000 gallons of acid water.

Complete cost data is presented in  appendices, Table 1.
                   Rotary Precoat  Vacuum Filtration

Results of rotary precoat vacuum filtration as  described in the de-
watering section indicate that  a cycle  time of  20  seconds filtration,
15 seconds drying and  10 seconds for  cutting was optimal for filtration
of the three lime sludges.  Norton sludge was not  amenable to this
dewatering system.   Costs were  estimated to range  from  $1.40 to $3.50
per 1,000 gallons of sludge dewatered.   With this  dewatering system
added to an existing neutralization system  additional costs would amount
to $0.35 to $1.80 per  1,000 gallons of  acid water  depending on the
treatment plant.  Complete cost data  is presented  in the appendices,
Tables 2 through 4.

                                 113

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                          Pressure Filtration

Laboratory experiments showed that all four sludges could he de-
watered by pressure filtration.  The filter media consisted of Johns-
Manville Celite 501 supported horizontally by a cloth.  The filter
media is washed away with the dried sludge at the end of each filter
cycle.  The filtrate from this process was of sufficient clarity for
direct discharge into a stream.

After consultation with Calvin Mohr,^12' of D. R. Sperry and Company,
required press sizes weJre determined for the respective treatment
plants.  All presses were of the 48 inch EHCL type, with the number of
plates and frame sizes dependent upon the particular sludge.  Due to
the filter sizes a plate shifter for each filter press would be re-
quired to handle the plates and frames during the cleaning process.

Two men would be required to disassemble, clean, and reassemble each
system.  In the systems with more than one press the operator would
rotate press units cleaning each press at the end of its cycle.

Electric pumps are used to provide pressure for the filtering pro-
cess.

Precoat use was based on minimum requirements without erosion, this
was determined to be 0.125 of an inch in laboratory tests.

The costs were estimated to range from $1.70 to $7.30 per 1,000 gallons
of sludge dewatered.  On the basis of total acid water to be treated,
the additional cost of dewatering would range from $0.02 to $2.40
per 1,000 gallons of acid water.  Complete cost data is presented in
Tables 5 through 8.
                        Porous Bed Filtration

Sewage sludge is generally applied to drying beds at a depth of 8 to
12 inches.(16)  As no information on optimum depth for acid mine drainage
sludge is available, a depth of one foot is assumed.  A cubic foot of
Edgell sludge at 2.7 percent solids would contain 1.685 pounds of
sludge.  Assuming a linear relationship between solids loading and
drying time and projecting the data from Figure 24, drying time
for a solids loading of 1.685 lbs/ft.2 is 34 days.

In a study by Barnard and Eckenfelder the capital costs of sludge
drying beds were estimated at $1.15 per square foot.(15)  With the
assumed 100,000 gallons of sludge per day from the Edgell Treatment
Plant and 34 days for a drying cycle, 454,580 square feet would be
required for one complete cycle.  This would require a capital cost
                                 114

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of $522,800.00.  Assuming a 10 year life  for  the  filter bed the vearlv
capital cost would be $52,280.00 or $143.00 per day.  At the afore-  '
stated clarifier underflow rate of 100,000 gallons" per day capital
costs would be reduced to $14.30 per 1,000 gallons of sludge dewatered.

Operational costs from the same study were calculated reflecting
solids content.  Their relationship was,

       Operating cost (c per 1000 gallons) =

            S x 1.2    (0.206 + 0.94 (1000/S0'5)
            Q x 3650

       0 = flow ratio in millions of gallons  per  day

       S » total solids in pounds per day.

With the assumed clarifier underflow at 2.7 percent solids, 22,520
pounds of solids would be produced each day.  Using these rates, an
operational cost of $4.80 per 1,000 gallons of sludge would be esti-
mated.

Total capital and operational costs for porous bed filtration of the
Edgell Treatment Plant sludge would be estimated  at $19.10 per 1,000
gallons of clarifier underflow sludge.  However,  this dewatering system
would increase total cost by $1.90 per 1,000  gallons of acid water.

Since the method of computation of dewatering costs used by Barnard
and Eckenfelder(15) differ in some respects from  that used in the
other sections of this evaluation, these  figures  may not be directly
comparable to the rest of this evaluation.
                         Thermal Spray Drying

Laboratory analysis of  thermal spray drying was conducted by Bowen
Engineering, Inc. U7)   Their recommendations as to plant requirements
were based on the dryer operating  temperature, the quantity of moisture
to be evaporated and ease of sludge moisture release.

Bowen Engineering determined the optimum operating temperatures as
an inlet temperature of 1200°F and an outlet temperature of approxi-
mately 300°F.  The quantity of moisture to be evaporated was extra-
polated from the assumed plant volumes and percent solids.  The specific
gravities of the four representative sludges were not significantly
larger than 1.00  (except for Norton at 1.05) so that the volume to
weight ratio approximates that of water.

Cost quotations for equipment include a direct fired air heater,
flame protection equipment, hot air inlet ducts, chamber outlet ducts,

                                 115

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a cyclone collector, a scrubber, a main exhaust fan, all recording
and controlling instrumentation, atomization equipment, structural
support steel, all motors and start up service.  Optional equipment
which would be required for sludge dewatering are a feed pump, penthouse
and access steel.

Most spray dryers use gas or oil direct fired air heaters; however,
an indirect system can be utilized using steam.  Because of the un-
availability of large amounts of natural gas for commercial use in
the Morgantown, W.Va. area; #2 fuel oil was chosen as the best
alternative for air heating.  Oil prices are based on conversation with
a local marketing representative of Atlantic Richfield Company.

Power consumption is basically for the operation of the blowers and
the feed pump.  Additional electricity is used for control instrumen-
tation; however, it is a small percentage of total energy requirements.

Continuous attendance during operation is not required by the systems.
A full time operator is not required; however, upon advice from the
manufacturer, costs were determined on the basis of one full time
worker.  This allows for infrequent periods when more than one worker
is required.  Costs were estimated to range from $15.00 to $19.00
per 1,000 gallons of sludge dewatered.  Adding this dewatering system
to an existing neutralization system would increase total cost by
$0.05 to $11.10 per 1,000 gallons of acid water depending on the treat-
ment plant.  Complete cost data is presented in the appendices, Tables 9
through 12.

The relatively high cost of spray drying could perhaps be justified
if transporting and disposing of the final dewatered sludge became a
major cost factor.  The spray dried sludge (approximately 90 percent
solids) is much drier than sludge produced by the other dewatering
methods.  Since more water is removed, this sludge becomes relatively
cheaper to transport and requires less area for disposal.
                            Centrifugation

Laboratory experiments showed that three sludges examined were accept-
able for dewatering by centrifugation.  Edgell Treatment Plant sludge
was not tested.  In all cases, the centrate produced was unacceptable
for direct discharge into a stream.  Therefore all centrates would
have to be recycled through a thickener clarifier to obtain sufficient
clarity.

After correspondence with Mr. R. A. Armstrong of Sharpies-Stokes
Division, Pennwalt Corporation, the required number of Sharpies Sludge
Pak SP-6500 centrifuges was determined for each treatment plant.  The
                                 116

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40 horsepower drive motor is the primary consumer of electric power;
however, small additional amounts are required for instrumentation and
control.

Costs were estimated to range  from  $1.80 to $4.50 per 1,000 gallons
of sludge dewatered.  The increase  in total cost of this dewatering
system over an existing neutralization system would be from $0.01 to
$1.73 per 1,000 gallons of  acid water.  Complete cost data is presented
in the appendices, Tables 13 through 15.
                                Summary

From the presented  cost  data it can  easily be observed that no one
method of dewatering was absolutely  advantageous  to all acid treatment
plant sludges.  Dewatering method  selection must  be related to the
particular  treatment plant,  taking into  consideration variables such
as acid water compositions,  method of  neutralization, quantity of sludge
produced and final  disposal  of  the dewatered sludge.  With respect to
each plant, significant  cost differences occurred in both costs based on
gallons of  sludge and  gallons of acid  water.  Summation of cost data for
each treatment  plant is  presented  in Tables 25  through 28.

Based on both the assumed amount of  sludge and  the amount of acid water,
centrifugation  was  deemed most  economical for Shannopin sludge.  This
sludge could be dewatered at a  cost  of $1.80 per  1,000 gallons of sludge
or $1.30 per 1,000  gallons of acid water.

Banning Treatment Plant  sludge  could be  dewatered at $1.40 per 1,000
gallons of  sludge by both rotary precoat vacuum filtration and centri-
fugation.   However, on the basis of  acid water  the cost would be $0.70
per 1,000 gallons of acid water.

Norton sludge dewatering would  cost  $3.30 per 1,000 gallons of sludge
by conventional vacuum filtration.  However, either conventional vacuum
filtration  or centrifugation systems could dewater the sludge at a cost
of $0.01 per 1,000  gallons of acid water.

It should be noted  again here that only  the Norton Treatment Plant
sludge possessed physical characteristics required for the conventional
vacuum filtration system of  dewatering.   Therefore no economic evaluation
was made with respect  to the other three sludges  using the conventional
vacuum filtration system of  dewatering.

Edgell Treatment Plant sludge was  most economically dewatered using
the rotary  precoat vacuum filtration method.  Based on sludge volume
dewatering  cost was $3.50 per 1,000  gallons of  sludge.  Using acid
water as a  criteria the  cost was $0.35 per 1,000  gallons of acid water.


                                 117

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Variations in cost occur between analyses based on sludge and acid
water because of assumptions made as to their respective solids content.
Thickening results in a denser sludge that requires less dewatering to
reach relative dryness.

The cost figures presented in Tables 25 through 28 are both for 1,000
gallons of sludge dewatered and as an add on cost per 1,000 gallons of
acid water treated.  Care must be taken in comparing the different de-
watering systems on the basis of an add on cost per 1,000 gallons of
acid water treated.  As a result of increasing the clarifier size, or the
retention time of the clarifier, the volume of sludge can be reduced
with respect to the original acid water volume.  In effect, the same
volume of acid water produces a thicker sludge with relatively less
volume.  Naturally, a thicker sludge is relatively less expensive
to dewater; however, the larger clarifier was not included in the cost
calculations.  The clarifier is normally a part of the neutralization
rather than the dewatering system.  Therefore in this analysis the
cost of dewatering per 1,000 gallons of acid water is biased in favor
of treatment systems producing relatively thicker sludges.
                                  118

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                                            Table 25

                          COST SUMMATION FOR SHANNOPIN TREATMENT PLANT

            COSTS BASED ON ASSUMPTIONS MADE IN ECONOMIC EVALUATION SECTION OF THIS REPORT
                               Capital
                                 Cost
Operational
   Cost
Cost per 1,000
Gallons Sludge
   Conventional
   Vacuum Filtration**

|l!  Rotary Precoat
Cost per 1,000
Gallons Acid Water*
Vacuum Filtration
Pressure Filtration
Porous Bed Filtration**
Thermal Spray Drying
Centrifugation
$85,800.00
$181,200.00

$714,800.00
$381,300.00
$428.00/day
$562.50/day

$2,591.50/day
$219, 30/ day
$2.50
$3.40

$15.50
$1.80
$1.80
$2.40

$11.10
$1.30
    Cost of dewatering the sludge produced by the neutralization of  1,000  gallons of acid water.
   **
    System not tested with this sludge.

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                                         Table 26

                        COST SUMMATION FOR BANNING TREATMENT PLANT

         COSTS BASED ON ASSUMPTIONS MADE IN ECONOMIC EVALUATION SECTION OF THIS REPORT
                            Capital
                              Cost

Conventional
Vacuum Filtration**

Rotary Precoat
Vacuum Filtration

Pressure Filtration
     5.

Porous Bed Filtration**

Thermal Spray Drying    $1,434,500.00

Centrifugation            $762,500.00
 Operational
    Cost
$5,005.80/day

  $282.10/day
Cost per 1,000
Gallons Sludge
$85,800.00
$144,900.00
$499.00/day
$563.50/day
$1.40
$1.70
     $15.00

      $1.40
Cost per 1,000
Gallons Acid Water*
        $0.75

        $0.80



        $7.50

        $0.70
 Cost of dewatering the sludge produced by the neutralization of 1,000 gallons of acid water.
**
 System not tested with this sludge.

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                                          Table 27

                        COST SUMMATION FOR NORTON TREATMENT PLANT

        COSTS BASED ON ASSUMPTIONS MADE IN ECONOMIC EVALUATION SECTION OF THIS REPORT
Conventional
Vacuum Filtration

Rotary Precoat
Vacuum Filtration**

Pressure Filtration

Porous Bed Filtration**

Thermal Spray Drying

Centrifugation
                           Capital
                             Cost
                           $52,000.00



                          $436,600.00

                          $152,500.00
Operational
   Cost
                           $43,500.00      $160.90/day
$351.20/day



$836.80/day

$181.60/day
Cost per 1,000
Gallons Sludge
                      $3.30
     $7.30



    $19.00

     $4.50
Cost per 1,000
Gallons Acid Water*
                          $0.01
      $0.02



      $0.05

      $0.01
 Cost of dewatering the sludge  produced by  the neutralization of 1,000 gallons of acid water.
**
 System not tested with this sludge.

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                                         Table 28

                         COST SUMMATION FOR EDGELL TREATMENT PLANT

         COSTS BASED ON ASSUMPTIONS MADE IN ECONOMIC EVALUATION SECTION OF THIS  REPORT

Conventional
Vacuum Filtration**

Rotary Precoat
Vacuum Filtration

Pressure Filtration

Porous Bed Filtration

Thermal Spray Drying

Centrifugation**
                            Capital
                              Cost
                           $76,600.00

                          $139,500.00

                          $522,800.00

                          $576,800.00
  Operational
     Cost
  $331.30/day

  $568.60/day

  $143.00/day

$l,573.80/day
                                                            Cost per 1,000
                                                            Gallons Sludge
Cost per 1,000
Gallons Acid Water*
$3.50
$6.00
$19.10
$17.30
$0.35
$0.60
$1.90
$1.73
 Cost of dewatering the sludge produced by the neutralization of 1,000 gallons of acid water.
**
 System not tested with this sludge.

-------
                             SECTION VIII

                           ACKNOWLEDGMENTS
Mr. Kdwin B. Wilson, now associated with Bethlehem Steel Corporation,
submitted the proposal for this project and his efforts are gratefully
acknowledged.

Thanks are due to Russell W. Frum who was  the author of the Economic
Evaluation Section of this report and Larry G. Shaffer who authored
portions of the Sludge Dewatering Section  of this report.  Messrs.
Russell W. Frum and Larry G. Shaffer also  performed much of the bench
scale tests during the data collection phase of this report.

The financial support of this  project by the Environmental Protection
Agency, Roger C. Wilnoth, Project Officer, and the State of West
Virginia, Coal Research Bureau, Joseph W.  Leonard, Director, is
acknowledged v/ith sincere thanks.

Mr. Richard B. Muter, Mr. Kenneth K. Humphreys and Mr. William F.
Lawrence are acknowledged for  their aid in the preparation of the
final report of this project.  Mr. Richard Muter also developed the
acid water collection and analysis procedure detailed later in this
report and assisted in the interpretation  of the results of the
chemical analyses.  Mr. Charles R. McFadden prepared the illustrations
for this report and Mr. Lionel L. Craddock prepared the photographs.
The cooperation of Miss Martha E. Fekete in typing this report is
gratefully acknowledged.
                                  123

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                              SECTION IX

                              REFERENCES
 1.   Salotto,  B.  V.;  Earth, E. F.; Ettinger, M. B.;  and Tulliver,
     W.  E.,  "Procedure for Determination of Mine Waste Acidity,"
     Federal Water Pollution Control Administration, Cincinnati,  Ohio
     (October  1966).

 2.   Standard  Methods for the Examination of Water and Wastewater,
     American  Public  Health Association, Inc., Twelfth Edition (1965).

 3.   Hall,  E.  A., Chemical Analysis of Coal Mine Drainage,  Consolidation
     Coal Company, pp 10 (August 1960).

 4.   FWPCA Method for Chemical Analysis of Water and Wastes,  U.  S.
     Department of Interior (November 1969).

 5.   Wilmoth,  R. C. and Scott, R. B., "Neutralizing of High Ferric  Iron
     Acid Mine Drainage," Third Symposium on Coal Mine Drainage  Research,
     Mellon Institute, Pittsburgh, Pennsylvania (1970).

 6.   Doe, P. W.; Benn, D.; and Bays, L. R., "The Disposal of Washwater
     Sludge by Freezing," Journal Institute of Water Engineers,  19,
     pp 251-275  (1965).

 7.   Clements, G. S.; Step hens on, R. J.; and Regan, C. J.,  "Sludge
     Dewatering by Freezing With Added, Chemicals," Journal Institute
     of Sewage Purification, Part 4, pp 318-337 (1950).

 8.   Cheng, C. Y.; Updegraff, D. M.; and Ross, L. W., "Sludge De-
     watering by High-Rate Freezing at Small Temperature Differences,"
     Environmental Science and Technology, 4^ No. 12, pp 1145-1147
     (December 1970).

 9.   Doe, P. W.; Benn, D.; and Bays, L. R., "Sludge Concentration
     by Freezing," Water and Sewage Works, 112, No. 11, pp 401-406
     (November 1965).

10.   "Filtration Leaf Test Procedures," Dorr-Oliver, Incorporated,
     Stamford, Connecticut, Bulletin No. 25ILT, pp 5-6.

11.   Arabia, L., Personal Communication, Eimco Processing Machinery
     Division, Envirotech Corporation, Pittsburgh, Pennsylvania
     (March 1972).

12.   Mohr,  C., Personal Communication, D. R. Sperry and Company,
     North Aurora Illinois (October 1971).
                                 125

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13.  "Laboratory Spray Dryers," Bowen Engineering,  Inc.,  North
     Branch, New Jersey.

14.  Kraufe, R., Personal Communication,  Sharpies-Stokes  Division,
     Pennwalt Corporation, Warminster, Pennsylvania (January 1972).

15.  Barnard, J. L. and Eckenfelder,  W. W.,  Jr.,  "Treatment-Cost
     Relationships For Industrial Waste Treatment," Technical
     Report Number 23, Environmental  and Water Resources  Engineering,
     Vanderbilt University,  Nashville, Tennessee  (1971).

16.  Eckenfelder, W. W. and Ford, D.  L.,  Water Pollution  Control,
     Jenkins Book Publishing Company  (1970).

17.  Hall, J. R., Personal Communication, Bowen Engineering, Inc.,
     North Branch, New Jersey (July 1971).

18.  Armstrong, R. A., Personal Communication, Sharpies-Stokes
     Division, Pennwalt Corporation,  Warminster,  Pennsylvania (April
     1972).
                                 126

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                               SECTION X

                              APPENDICES


                               Table 29

      Conventional Vacuum Filtration - Norton Treatment Plant Sludge
                    (Preliminary Prices - Spring 1972)
Capital Costs

6 foot diameter x 6 foot
drum filter with accessories   $30,000.00

Construction and Installation:
35 percent of equipment         10^500.00
Total Equipment Cost           $40,500.00

Equipment Depreciation:
10 years expected life
no salvage value

Building:  300 sq. ft. at
$10.00/sq. ft.                   3,000.00

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost             $43,500.00

Operational Costs

Maintenance:  6 percent of
total capital cost

Electricity:  530 KWH/day
at $0.0175 KWH

Labor:  24 hours at $6.00/hour
Total Capital and Operational Cost

Assuming 50,000 gallons
clarifier underflow per day
$4,050.00/year
  $100.00/year
                $11.10/day
                  0.30/day
Assuming 20,000,000 gallons acid
water per day
                                  127
$2,790.00/year    7.60/day
                  9.30/day

               $144.00/day
               $172.30/day

                 $3.30/1,000
                 gallons
                 sludge de-
                 watered

                 $0.01/1,000
                 gallons  acid
                 water

-------
                               Table 30

  Rotary Precoat Vacuum Filtration - Shannopin Treatment Plant Sludge
                  (Preliminary Prices - Spring 1972)
Capital Costs

Equipment:  Includes one 10
foot diameter x 17 foot face
vacuum filter with all motors,
vacuum pump with motor, vacuum
receivers, filtrate pump with
motor, precoat mix tank with
motor and precoat slurry pump  $59,100.00

Construction and Installation:
35 percent of equipment         20.700.00
Total Equipment Cost           $79,800.00

Equipment Depreciation:
10 years expected life
no salvage value

Building:  600 sq. ft. at
$10.00/sq. ft.                   6,000.00

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost             $85,800.00

Operational Costs

Maintenance:  6 percent of
total capital cost

Electricity:  2,250 KWH/day
at $0.0175/KWH

Labor:  24 hours at $6.00/hour

Precoat:  Johns-Manville Hyflo
Super-Cel, $68.00/ton F.O.B.
California warehouse, $100.40/ton
delivered Morgantown, W.Va.
$7,980.00/year
                $21.90/day
  $200.00/year
                  0.50/day
$5,150.00/year  $14.10/day


                 39.40/day

               $144.00/day
               $230.50/day
                                 128

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                         Table 30  (Continued)
Total Capital and Operational Cost                        $450.40/day

Assuming 180,000 gallons                                    $2.50/1,000
clarifier underflow per day                                 gallons
                                                            sludge de-
                                                            watered

Assuming 250,000 gallons acid                               $1.80/1,000
water per day                                               gallons acid
                                                            water
                                 129

-------
                               Table 31

   Rotary Precoat Vacuum Filtration - Banning Treatment Plant Sludge
                  (Preliminary Prices - Spring 1972)
Capital Costs

Equipment:  Includes one 10
foot diameter x 17 foot face
vacuum filter with all motors,
vacuum pump with motor, vacuum
receivers, filtrate pump with
motor, precoat mix tank with
motor and precoat slurry pump  $59,140.00

Construction and Installation:
35 percent of equipment         20,700.00
Total'Equipment Cost           $79,800.00

Equipment Depreciation:
10 years expected life
no salvage value

Building:  600 sq. ft. at
$10.00/sq* ft.                   6,000.00

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost             $85,800.00

Operational Costs

Maintenance:  6 percent of
total capital cost

Electricity:  2,250 KWH/day
at $0.0175/KWH

Lahor:  24 hours at $6.00/hour

Precoat:  Johns-Manville Celite
501,  $73.00/ton F.O.B.
California warehouse, $105.40/ton
delivered Morgantown, W.Va.
$7,980.00/year
                $21.90/day
  $200.00/year
                  0.50/day
$5,150.00/year  $14.10/day


                 39.40/day

               $144.00/day
               $301.50/day
                                130

-------
                         Table 31  (Continued)
Total Capital and Operational Cost                        $521.40/day

Assuming 360,000 gallons                                    $1.40/1,000
clarifier underflow per day                                 gallons
                                                            sludge de-
                                                            watered

Assuming 720,000 gallons acid                               $0.75/1,000
water per day                                               acid water
                                  131

-------
                               Table 32

   Rotary Precoat Filtration - Edgell Treatment Plant Sludge
                  (Preliminary Prices - Spring 1972)
Capital Costs

Equipment:  Includes one 10
foot diameter x 14 foot face
vacuum filter with all motors,
vacuum pump with motor, vacuum
receivers, filtrate pump with
motor, precoat mix tank with
motor and precoat slurry pump  $53,000.00

Construction and Installation:
35 percent of equipment        __ 18,600.00
Total Equipment Cost           $71,600.00

Equipment Depreciation:
10 years expected life
no salvage value

Building:  500 sq. ft. at
$10.00/sq. ft.                   5,000.00

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost             $76,600.00

Opera tional Cos ts

Maintenance:  6 percent of
total capital cost

Electricity:  1,880 KWH/day
at $0.0175/KWH

Labor:  24 hours at $6.00/hour

Precoat:  Johns-Manville Celite
501, $73.00/ton F.O.B.
California warehouse, $105.40/ton
delivered Morgantown, W.Va.
$7,160.00/year
                $19.60/day
  $166.00/year
                  0.50/day
$4,600.00/year  $12.60/day


                 32.90/day


               $144.00/day
               $141.80/day
                                 132

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                         Table 32 (Continued)
Total Capital and Operational Cost                        $351.40/day

Assuming 100,000 gallons                                    $3.50/1,000
clarifier underflow per day                                 gallons
                                                            sludge de-
                                                            watered

Assuming 1,000,000 gallons acid                             $0.35/1,000
water per day                                               gallons acid
                                                            water
                                  133

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                               Table 33

        Pressure Filtration - Shannopin Treatment Plant Sludge
                    (Preliminary Prices - Spring 1972)
Capital Costs

4-48 inch filter presses
  at $20,000.00                $80,000.00
4-plate shifters at
  $2,400.00 each                 9,600.00
Feed pump with accessories         900.00
Precoat equipment at
  $5,000.00 each                20,000.00

Construction and Installation:
35 percent of equipment
Total Equipment Cost

Equipment Depreciation:
10 years expected life
no salvage value

Building:  3,200 sq. ft. at
$10.00/sq. ft.                  32,000.00

Building Depreciation:
30 years expected life
no salvage value
  38.700.00
$149,200.00
Total Capital Cost

Operational Costs

Maintenance:  6 percent of
total capital cost

Electricity:  270 KWH/day
at $0.0175/KWH

Labor:  24 hours, 2 men at
$6.00/hour each
Precoat:  Johns-Manville Celite
501, $73.00/ton F.O.B.
California warehouse, $105.40/ton
delivered Morgantown, W.Va.
$181,200.00
             $14,920.00/year
                             $40.90/day
               1,066.00/year
                               2.90/day
             $10,874.00/year
                             $29.80/day

                               4.70/day



                             $288.00/day
                            $240.00/day
                                 134

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                         Table 33  (Continued)
Total Capital and Operational Cost                        $606.30/day

Assuming 180,000 gallons                                    $3.40/1,000
clarifier underflow per day                                 gallons
                                                            sludge de-
                                                            watered

Assuming 250,000 gallons acid                               $2.40/1,000
water per day                                               gallons acid
                                                            water
                                  135

-------
                               Table 34

         Pressure Filtration - Banning Treatment Plant Sludge
                   (Preliminary Prices - Spring 1972)
Capital Costs

3-48 inch filter presses
  at $23,000.00 each
3-plate shifters at
  $2,300.00 each
Feed pump with accessories
Precoat equipment at
  $5,000.00 each

Construction and Installation:
35 percent of equipment
Total Equipment Cost

Equipment Depreciation:
10 years expected life
no salvage value

Building:  2,100 sq. ft. at
$10.00/sq. ft.

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost

Operational Costs

Maintenance:  6 percent of
total capital cost

Electricity:  270 KWH/day
$0.0175/KWH

Labor:  24 hours, 2 men at
$6.00/hour each
Precoat:  Johns-Manvilie Celite
501, $73.00/ton F.O.B.
California warehouse, $105.50/ton
delivered Morgantown, W.Va.
 $69,000.00

   6,900.00
     900.00

  15,000.00
  32,100.00
$123,900.00
  21,000.00
$144,900.00
             $12,390.00/year
                             $33.90/day
                $700.00/year
                               1.90/day
              $8,694.00/year
                             $23,

                               4,
80/day

70/day
                            $288.00/day
                            $247.00/day
                                 136

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                         Table 34  (Continued)
Total Capital and Operational Cost                        $599.30/day

Assuming 360,000 gallons                                    $1.70/1,000
clarifier underflow per day                                 gallons
                                                            sludge de-
                                                            watered

Assuming 720,000 gallons  acid                               $0.80/1,000
water per day                                               gallons acid
                                                            water
                                   137

-------
                               Table 35

         Pressure Filtration - Norton Treatment Plant Sludge
                  (Preliminary Prices - Spring 1972)
Capital Costs

1-48 inch filter press         $21,000.00
1-plate shifter                  2,700.00
Feed pump with accessories         900.00
Precoat equipment                5,000.00

Construction and Installation:
35 percent of equipment         10,400.00
Total Equipment Cost           $40,000.00

Equipment Depreciation:
10 years expected life
no salvage value

Building:  1,200 sq. ft. at
$10.00/sq. ft.                  12,000.00

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost             $52,000.00

Operational Costs

Maintenance:  6 percent of
total capital cost

Electricity:  270 KWH/day
at $0.0175 KWH

Labor:  24 hours, 2 men at
$6.00/hour each

Precoat:  Johns-Manville Celite
501, $73.00/ton F.O.B.
California warehouse, $105.40/ton
delivered Morgantown, W.Va.
$4,000.00/year
                $11.00/day
  $400.00/year
                  1.00/day
$3,120.00/year
                  8.50/day

                  4.70/day



               $288.00/day
                 50.00/day
                                 138

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                         Table 35  (Continued)
Total Capital and Operational Cost                        $363.20/day

Assuming 50,000 gallons                                     $7.30/1,000
clarifier underflow per day                                 gallons
                                                            sludge de-
                                                            watered

Assuming 20,000,000 gallons  acid                            $0.02/1,000
water per day                                               gallons acid
                                                            water
                                  139

-------
                               Table 36

         Pressure Filtration - Edgell Treatment Plant Sludge
                  (Preliminary Prices - Spring 1972)
Capital Costs

3-48 inch filter presses
  at $22,500.00 each
3-plate shifters at
  $2,200.00 each
Feed pump with accessories
Precoat equipment at
  $5,000.00 each

Construction and Installation:
35 percent of equipment
Total Equipment Cost

Equipment Depreciation:
10 years expected life
no salvage value

Building:  1,800 sq. ft. at
$10.00/sq. ft.

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost

Operational Costs

Maintenance:  6 percent of
total capital cost

Electricity:  270 KWH/day
at $0.0175/KWH

Labor:  24 hours, 2 men at
$6.00/hour each
Precoat:  Johns-Manville Celite
501, $73.00/ton F.O.B.
California warehouse, $105.40/ton
delivered Morgantown, W.Va.
 $67,500.00

   6,600.00
     900.00

  15,000.00
  31,500.00
$121,500.00
  18,000.00
$139,500.00
             $12,150.00/year
                             $33.30/day
                $600.00/year
                               1.60/day
              $8,370.00/year
                             $22


                               4


                            $288
,90/day


,70/day


,00/day
                            $253.00/day
                                 140

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                         Table 36 (Continued)
Total Capital and Operational Cost                        $603.50/day

Assuming 100,000 gallons                                    $6.00/1,000
clarifier underflow per day                                 gallons
                                                            sludge de-
                                                            watered

Assuming 1,000,000 gallons acid                             $0.60/1,000
water per day                                               gallons acid
                                                            water
                                  141

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                               Table 37

        Thermal Spray Drying - Shannopin Treatment Plant Sludge
                  (Preliminary Prices - Spring 1972)
Capital Costs

1-36 foot spray drying
  system
                               $500,000.00
                               $181,300.00
                               $706,300.00
                               $714,800.00
Equipment Options:
Feed Pump                         7,000.00
Access Steel                     18,000.00

Construction and Installation:
35 percent of equipment
Total Equipment Cost

Equipment Depreciation:
10 years expected life
no salvage value

Penthouse (Building)             $8,500.00

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost

Operational Costs

Maintenance:  6 percent of
total capital cost

Fuel:  #2 fuel oil, 16,900
gallons/day at $0.13/gallon

Electricity:  7,600 KWH/day
at $0.0175/KWH

Labor:  24 hours at $6.00/hour

Total Capital and Operational Cost

Assuming 180,000 gallons
clarifier underflow per day
                                 142
                                           $70,630.00/year
                                                           $193.50/day
                                               $23.00/year
                                                             $0.10/day
                                           $42,888.00/year
                                                           $117.50/day
$2,197.00/day


  $133.00/day

  $144.00/day

$2,785.10/day

   $15.50/1,000
   gallons
   sludge de-
   watered

-------
                        Table 37  (Continued)
Assuming 250,000 gallons acid                              $11,10/1,000
water per day                                              gallons acid
                                                           water
                                  143

-------
                               Table 38

        Thermal Spray Drying - Banning Treatment Plant Sludge
                  (Preliminary Prices - Spring 1972)
Capital Costs

2-36 foot spray drying
  systems at $500,000.00 each  $1,000,000.00
Equipment Options:
Feed Pump
Access Steel

Construction and Installation:
35 percent of equipment
Total Equipment Cost

Equipment Depreciation:
10 years expected life
no salvage value

Penthouse (Building)

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost

Operational Costs

Maintenance:  6 percent of
total capital cost

Fuel:  #2 fuel oil, 34,300
gallons/day at $0.13/gallon

Electricity:  15,200 KWH/day
at $0.0175/KWH
Labor:  24 hours at $6.00/hour

Total Capital and Operational Cost

Assuming 360,000 gallons
clarifier underflow per day
    14,000.00
    36,000.00
  $367,500.00
$1,417,500.00


            $141,750.00/year


   $17,000.00
$388.40/day
                $567.00/year
                              $1.60/day
$1,434,500.00
             $86,070.00/year
                                 144
                            $250.80/day


                          $4,459.00/day


                            $152.00/day

                            $144.00/day

                          $5,395.80/day

                             $15.00/1,000
                             gallons
                             sludge de-
                             watered

-------
                        Table  38  (Continued)



Assuming 720,000 gallons acid                               <7 cn/1 nnn
water per day                                               ?7.50/1,000
                                                            gallons acid
                                                            water
                                 145

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                               Table 39

        Thermal Spray Drying - Norton Treatment Plant Sludge
                  (Preliminary Prices - Spring 1972)
Capital Costs

1-30 foot spray drying
  system
                               $300,000.00
                               $111,100.00
                               $428,600.00
                               $436,600.00
Equipment Options:
Feed Pump                         3,500.00
Access Steel                     14,000.00

Construction and Installation:
35 percent of equipment
Total Equipment Cost

Equipment Depreciation:
10 years expected life
no salvage value

Penthouse (Building)             $8,000.00

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost

Operational Costs

Maintenance:  6 percent of
total capital cost

Fuel:  #2 fuel oil, 4,300
gallons/day at $0.13/gallon

Electricity:  6,200 KWH/day
at $0.0175/KWH

Labor:  24 hours at $6.00/hour

Total Capital and Operational Cost

Assuming 50,000 gallons
clarifier underflow per day
                                 146
                                           $42,860.00/year
                                                           $117.40/day
                                              $267.00/year
                                                             $0.70/day
                                           $26,196.00/year
 $71.80/day


$559.00/day


  62.00/day

$144.00/day

$954.90

 $19.00/1,000
 gallons
 sludge de-
 watered

-------
                         Table 39  (Continued)
Assuming 20,000,000 gallons acid                 ,           $0.05/1,000
water per day                                               gallons acid
                                                            water
                                  147

-------
                               Table 40

        Thermal Spray Drying - Edgell Treatment Plant Sludge
                  (Preliminary Prices - Spring 1972)
Capital Costs

1-34 foot spray drying
  system
                               $400,000.00
                               $147.300.00
                               $568,300.00
                               $576,800.00
Equipment Options:
Feed Pump                         5,000.00
Access Steel                     16,000.00

Construction and Installation:
35 percent of equipment
Total Equipment Cost

Equipment Depreciation:
10 years expected life
no salvage value

Penthouse (Building)             $8,500.00

Building Depreciation:
30 years expected life
no salvage value

Total Capital Cost

Operational Costs

Maintenance:  6 percent of
total capital cost

Fuel:  #2 fuel oil, 9,300
gallons/day at $0.13/gallon

Electricity:  7,200 KWH/day
at $0.0175/KWH

Labor:  24 hours at $6.00/hour

Total Capital and Operational Cost

Assuming 100,000 gallons
clarifier underflow per day
                                 148
                                           $56,830.00/year
                                                           $155.70/day
                                              $283.00/year
                                                             $0.80/day
                                           $34,608.00/year
                                                            $94.80/day
$l,209.00/day


   126.00/day

   144.00/day

$l,730.30/day

   $17.30/1,000
   gallons
   sludge de-
   watered

-------
                        Table 40  (Continued)
Assuming 1,000,000 gallons acid                             $1.73/1,000
water per day                                               gallons acid
                                                            water
                                  149

-------
                               Table 41
          Centrifugation - Shannopin Treatment Plant Sludge
                   (Preliminary Prices - Spring 1972)
Capital Costs

5-Sharples Sludge Pak
  SP-6500 centrifuge,
  $55,000.00 each              $275,000.00

Construction and Installation:
35 percent of equipment          96.300.00
Total Equipment Cost           $371,300.00

Equipment Depreciation:                    $37,200.00/year
10 years expected life                                      $101.91/day
no salvage value

Building:  1,000 sq. ft. at
$10.00/sq. ft.                  $10,000.00

Building Depreciation:                        $33.00/year
30 years expected life                                       $0.90/day
no salvage value

Total Capital Cost             $381,300.00

Operational Costs

Maintenance:  6 percent of                 $22,878.00/year
total capital cost                                          $62.70/day

Electricity:  720 KWH/day
at $0.0175/KWH                                               12.60/day

Labor:  24 hours at $6.00/hour                              $144.00/day

Total Capital and Operational Cost                          $322.10/day

Assuming 180,000 gallons                                     $1.80/1,000
clarifier underflow per day                                  gallons
                                                             sludge de-
                                                             watered

Assuming 250,000 gallons acid                                $1.30/1,000
water per day                                                gallons acid
                                 150                         water

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                               Table 42

            Centrifugation - Banning Treatment Plant Sludge
                  (Preliminary Prices - Spring 1972)
Capital Costs

10-Sharples Sludge Pak
  SP-6500 centrifuge,
  $55,000.00 each               $550,000.00

Construction and Installation:
35 percent of equipment         192,500.00
Total Equipment Cost            $742,500.00

Equipment Depreciation:                    $74,250.00/year
10 years expected life                                     $203.40/day
no salvage value

Building:  2,000 sq. ft. at
$10.00/sq. ft.                  $20,000.00

Building Depreciation:                        $667.00/year
30 years expected life                                       $1.80/day
no salvage value                \

Total Capital Cost              $762,500.00

Operational Costs

Maintenance:  6 percent of                 $45,750.00/year
total capital cost                                         $125.50/day

Electricity:  720 KWH/day
at $0.0175 KWH                                               12.60/day

Labor:  24 hours at $6.00/hour                             $l44.00/day

Total Capital and Operational Cost                         $487.10/day

Assuming 360,000 gallons                                     $1.40/1,000
clarifier underflow per day                                  gallons
                                                             sludge de-
                                                             watered

Assuming 720,000 gallons acid                                $0.70/1,000
water per day                                                gallons  acid
                                                             water
                                 151

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                                Table 43

            Centrifugation - Norton Treatment Plant Sludge
                   (Preliminary Prices - Spring 1972)
                                $110,000.00


                                  38,500.00
                                $148,500.00
Capital Costs

2-Sharpies Sludge Pak
  SP-6500 centrifuge,
  $55,000.00 each

Construction and Installation:
35 percent of equipment
Total Equipment Cost

Equipment Depreciation:
10 years expected life
no salvage value
Building:  400 sq.  ft.  at
$10.00/sq. ft                     $4,000.00

Building Depreciation:
30 years expected life
no salvage value

Total Capital CCost

Operational Costs

Maintenance:  6 percent of
total capital cost

Electricity:  720 KWH/day
at $0.0175/KWH

Labor:  24 hours at $6.00/hr

Total Capital and Operational  Cost

Assuming 50,000 gallons
clarifier underflow per day
Assuming 20,000,000 gallons acid
water per day
                                            $14,850.00/year
                                                            $40.70/day
                                               $133.00/year
                                                             $0.40/day
                                $152,500.00
                                             $9,150.00/year
                                                            $25.00/day


                                                             12.60/day

                                                           $144.00/day

                                                           $222.70/day

                                                             $4.50/1,000
                                                             gallons
                                                             sludge de-
                                                             watered

                                                             $0.01/1,000
                                                             gallons acid
                                                             water
                                  152
                                         «U,S. GOVERNMENT PRINTING OFFICE: 1973 514-513/208 1-3

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  SELECTED WATER
  RESOURCES ABSTRACTS
  INPUT TRANSACTION FORM
                      1. Report No.
               2.
  4. Title
           Devatering of Mine Drainage  Sludge - Phase  II
  7. Aathor(s)
           David J. Akers,  Jr., "• Edward A. Moss
  9.  Organization
          Wost Virginia University
          Morgantown, W. Va.
 3. Accession No.

 W

 5. Report Date
 6.
 8. Performing Organization
   Report No.

10. Project No.

    •RPA -
  12.  Sponsoring Organization

  15.  Supplementary Notes
                                          11. Contract/Grant No.

                                             Grant 14010 FJX
                                          13. Type of Report and
                                         ''    Period Covered
          Environmental Protection Agency report
          number, EPA-R2-73-169, February 1973.
  u. Abstract A study  of various acid  mine drainage  sludge  conditioning methods and  de-
 watering systems was  made.  Acid mine drainage &  sludge  from neutralization plants were
  iharacterized.  Four  sludges were selected as being representative of the various types
 of sludges produced by the lime/limestone neutralization of acid mine drainage.
      The conditioning methods studied were:  freezing, use of flocculants, and use of
 filter aids.  The six dewatering systems evaluated were:  1,  conventional, rotary
 vacuum filtration,  2. rotary precoat vacuum filtration,  3. pressure filtration, U.
 porous bed filtration, 5. thermal spray drying, and 6. centrifugation.
      Ho single dewatering system was found best for all  acid mine drainage sludges.   On
 the basis of cost,  the most promising acid mine drainage sludge dewatering techniques
 appear to be centrifugation, rotary vacuum filtration and rotary precoat vacuum filtra-
 tion.
  17a. Descriptors                                           .      ,     , . .         ,  . „    , .
    Acid Mine Drainage* neutralization* sludge* freezxng,  flocculation, cenorifugation
  17b. Identifiers

    filter aid* vacuum filtration* pressure filtration*
  17c. COWRR Field & Group   05D
  18. Availability
19. Security Class.
   (Report)

20. Security Class.
   (Page)
21. No. of
   Pages

22. Price
                                                        Send To:
                                                        WATER RESOURCES SCIENTIFIC INFORMATION CENTER
                                                        US DEPARTMENT OF THE INTERIOR
                                                        WASHINGTON. D. C. 20240
  Abstractor Ronald D. Hill

WRSIC 102 (REV. JUNE 1971)
             | institution    Environmental Protection Agency
                                                         SPO 913.261

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