EPA-600/2-77-015
March 1977
Environmental Protection Technology Series
TREATMENT OF
COMBINED SEWER OVERFLOWS BY
HIGH GRADIENT MAGNETIC SEPARATION
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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EPA-600/2-77-015
March 1977
TREATMENT OF COMBINED SEWER OVERFLOWS
BY HIGH GRADIENT MAGNETIC SEPARATION
by
David M. Allen
Richard L. Sargent
John A. Oberteuffer
Sala Magnetics, Inc.
Cambridge, Massachusetts 02142
Contract No. 68-03-2218
Project Officer
Hugh Masters
Storm and Combined Sewer Section
Wastewater Research Division
Municipal Environmental Research Laboratory (Cincinnati)
Edison, New Jersey 08817
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views and
polices of the U.S. Environmental Protection Agency, nor does mention of trade
names or commercial products constitute endorsement or recommendation for use.
ii
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem
solution and it involves defining the problem measuring its impact, and
searching for solutions. The Municipal Environmental Research Laboratory
develops new and improved technology and systems for the hazardous water
pollutant discharges from municipal and community sources, for the pre-
servation and treatment of public drinking water supplies, and to minimize
the adverse economic, social, health, and aesthetic effects of pollution.
This publication is one of the products of that reasearch; a most vital
communications link between the researcher and the user community.
Many of our cities are faced with pollution problems associated with
combined sewer overflows. Contamination of surface waters with sewage occurs
following heavy precipitation or snow melts. Conventional treatment has
failed to reduce, significantly, pollution caused by these surges of contami-
nated water. High gradient magnetic separation offers an efficient means
of removing pollutants from combined sewer overflow.
Results of earlier studies show that high gradient magnetic separation
removes more than ninety percent of suspended solids from water. These
include algae, bacteria and viruses as well as non-living biocolloids. The
process also removes significant quantities of dissolved BOD, COD, and heavy
metals. This report describes bench and pilot level studies of high gradient
magnetic separation treatment of combined sewer overflow to the Charles River
at Cambridge, Massachusetts.
Francis T. Mayo,
Director
Municipal Environmental
Research Laboratory
111
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ABSTRACT
Seeded water treatment by high gradient magnetic separation techniques
was carried out on combined storm overflows and raw sewage influents. Both
bench-type and continuous pilot plant tests were performed to evaluate the
effectiveness of the process in purifying waste waters. Critical parameters
were varied to determine optimal removal efficiencies, sensitivities and
relative importances of these variables. Attempts were also made to compare
the effectiveness and economic feasibility of high gradient magnetic separa-
tion treatment with present methods of waste water treatment. Finally,
recommendations for the next phases of study have been presented.
The results of the present study show this process to be a highly
effective method of reducing most forms of pollutants present in CSO and raw
sewage to low levels of contamination. Capital cost estimates for high
gradient magnetic separation systems also compare favorably with traditional
secondary plants. Several additional benefits are realized such as extremely
high processing rates, small land requirements, and lower chlorine demand
(ecological benefits).
This report was submitted in fulfillment of Contract No. 68-03-2218 by
Sala Magnetics, Inc. under the sponsorship of the U. S. Environmental
Protection Agency. This report covers the period of June, 1975 to July, 1976,
IV
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CONTENTS
Page
Foreword ill
Abstract iv
List of Figures viii
List of Tables ix
Acknowledgements x
Sections
I Conclusions 1
II Recommendations 3
III Summary 6
Optimal Performance 6
Summarized Average Data 7
Solids Removal 7
Biological Material Removal 7
Removal of Chemical Species 8
Removal Effectiveness in Comparison to Conventional 8
Treatment
Parameter Ranges Tested 8
Relative Importances, Sensitivities and Interactions 11
of Parameters
IV Introduction 12
Overview of High Gradient Magnetic Separation 12
Principles of High Gradient Magnetic Filtration 14
Magnetic and Competing Forces 14
Maximizing the Magnetic Forces 14
The Ferromagnetic Matrix 14
Production of Strong Magnetic Fields 17
The Operating Variables of the Separator 17
High Gradient Magnetic Separators 19
High Gradient Magnetic Filtration Techniques in Water 19
Treatment
v
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Page
Applications for High Gradient Magnetic Separation to 22
Water Treatment
Suspended Solids Removal 22
Steel Mill Waste and Process Waters 22
Other 22
Heavy Metals Removal 22
Bacteria Removal 22
Algae Removal 25
Virus Removal 25
Dissolved Phosphorus Removal 25
Color and Turbidity Removal 25
Objectives of Study 28
V Experimental Design 29
Bench Test Apparatus Design 29
Pilot Plant Apparatus 29
Design 29
Flexibility and Capacity 36
VI Methods and Procedures 37
Bench Tests 37
Test Procedures 37
Scope of Testing 37
Pilot Plant 38
Test Procedures 38
Scope of Testing 38
Analytical Procedures Used in Bench and Pilot Testing 39
Sample Collection 39
Analytical Laboratory Facilities 42
VII Testing Programs Performed 44
Bench Testing Performed 44
Pilot Plant Runs 46
VIII Results and Discussion 48
Introduction 48
Interacting Chemical Parameters 48
Alum 48
Polyelectrolyte 49
pH 52
VI
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Page
Magnetic Parameters and Their Interactions 52
Magnetite Seed 52
Magnetic Field Strength 56
Flow Velocity and Residence Time 56
Matrix Loading 56
Optimal Parameter Runs 59
IX Comparison of High Gradient Magnetic Separation 64
to Conventional Treatment
Cost Comparisons 64
Comparison of Removal Performance 67
Application to Effluent Polishing 67
X Cost Estimates for High Gradient Magnetic 68
Separation Treatment
Operation and Maintenance 71
Land Requirements 71
References 74
Appendix A - Tables of Summarized Data 76
Appendix B - Cumulative Probability Charts 90
Appendix C - Raw Data 92
Appendix D - Glossary 112
Appendix E - Abbreviations and Magnetic Units 114
Appendix F - Conversion Factors 115
VII
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LIST OF FIGURES
Number Page
IV-1 Sala 5 tph Kaolin Clay Pilot Plant 13
IV-2 Cutaway View of High Gradient Magnetic Separator 15
IV-3 Matrix Materials Used in High Gradient Magnetic Separators 16
IV-4A Comparison of Prior Art and Sala High Gradient Magnetic 18
-4B Separators
IV-5 Cross Section of Static High Gradient Magnetic Separator 20
V-l Initial Bench Test Apparatus 30
V-2 Redesigned Bench Study Installation 31
V-3 Sala Continuous Pilot Plant 32
V-4 Pilot Plant Automatic Controller 33
V-5 Pilot Plant Power Supply and Monitoring System 34
V-6 Flow Sheet of Seeded Water Treatment Pilot Plant 35
VI-1 Storage Tanks for CSO Samples 40
VI-2 Water Analysis Laboratory at Sala Magnetics, Inc. 43
VIII-1 Alum Concentration Versus % Removal 50
VIII-2 Polyelectrolyte Concentration Versus % Removal 51
VIII-3 pH Versus Suspended Solids 53
VIII-4 Magnetic Seed Concentration Versus % Removal 54
VIII-5 Magnetic Field Strentgh Versus % Removal 55
VIII-6 Flow Rate (Floe Residence Time) Versus % Removal 57
VIII-7 Matrix Loading (Time in Cycle) Versus % Removal 58
VIII-8 Continuous Pilot Plant Repeated Cycles Versus % Removal 60
VIII-9 Coliform Bacteria in Continuous Pilot Plant Run 63
X-l 25 MGD SALA-HGMS Integrated Wet and Dry Weather Combined 69
Sewer Treatment Facility
VI11
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LIST OF TABLES
Number Page
III-l Optimal Pilot Plant Performance 6
III-2 Solids Removals by High Gradient Magnetic Separation 7
in CSO and Sewage
III-3 Biological Material Removed by High Gradient Magnetic 7
Separation
III-4 Trace Metal Removal by High Gradient Magnetic Separation 8
III-5 Relative Efficiencies of CSO Treatment Operations 9
III-6 Relative Efficiencies of Sewage Treatment Operation 10
and Processes
IV-1 Results Obtained Using High Gradient Magnetic Separation 23
to Treat Steel Mill Process and Waste Waters
IV-2 Concentration of Metal Ions in Influent and Effluent 24
IV-3 Treatment of Plating Waste Water 24
IV-4 Removal of Polio Virus from Water Using High Gradient 26
Magnetic Separation
IV-5 Letter from T. G. Metcalf 27
VI-1 Comparison of Methods of Collection 41
IX-1 Comparison of CSO Treatment Processes 65
IX-2 Comparison Between High Gradient Magnetic Separation 66
and Other Sewage Treatment Processes
X-l 25 MGD Integrated Wet and Dry Weather Flow Treatment 68
Facility
X-2 Design Parameter Values Used in Obtaining Estimated Costs 70
X-3 Operation and Maintenance Costs 72
X-4 Power Consumption 73
Al-12 Summarized Data 76-89
Bl-2 Probability Charts 90-91
C Raw Data 92-111
IX
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ACKNOWLEDGEMENTS
Special thanks are given to Professor Ralph Mitchell of Harvard
University for his many contributions and consultations throughout this
project. Without his guidance, the success of this work might not have
been possible. The assistance given by Frank Zinfolino, supervisor of the
Cottage Farm Chlorination and Detention Facility in collection of CSO samples
was greatly appreciated.
Further thanks are given to Hugh Masters, Project Officer, Richard
Field, Chief, and Richard P. Traver, Staff Engineer, Storm & Combined Sewer
Section, U.S. Environmental Protection Agency for their cooperation and
assistance. Albe Dawson was technical editor, and Warren Ames provided
graphics.
This project was conducted under the supervision of John A.
Oberteuffer, Chief Investigator and Bo Arvidson, Process Development Dir-
ector. All experimental design and testing was carried out by Project
Engineers David Allen and Richard Sargent with the help of Susan Winkelman,
Laboratory Technician. The report was written by David Allen, and Richard
Sargent, with assistance from Ralph Mitchell.
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SECTION I
CONCLUSIONS
• Single-step processing of combined storm overflows or of raw sewage with
high gradient magnetic separation results in the production of effluents
at high flow rates which significantly surpass other secondary process
effluents in purity.
• Effluent quality is excellent. The percentage removals of pollutants
(average from all testing performed) are given below:
% Removal From:
Pollutant CSO Sewage
Suspended Solids 95 91
Turbidity 93 88
Apparent Color 87 82
Fecal Coliform > 99 > 99
BOD (Total) > 92
COD 75 67
• Testing has shown that optimization of parameters (through jar tests and
solids loading determinations) can yield even higher removal efficiencies.
A summary of the percent removals achieved on a heavily loaded sample of
CSO under estimated optimum conditions is given below:
Pollutant Optimized Run on CSO (% Removals)
Suspended Solids 98.7
Turbidity 96
Apparent Color 93
Fecal Coliform 99.85
BOD5 (Total) > 92
• Alum concentration and pH were found to be the most sensitive parameters
in the process. Their interactions with each other and with other com-
ponents in the influent stream were of major importance in the production
of good coagulation, essential to this process.
• Polyelectrolyte and magnetic seed concentrations were critical to sepa-
ration efficiency only when approaching the low ends of their effective
concentration ranges. Likewise, magnetic field strength was not critical
above a certain minimum level defined by the solids present, seed and
flocculants concentrations and flow rate used.
1
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• A detention time of 3 minutes for the entire flocculation-seeding process
plus magnetic separation was adequate for all CSO and raw sewage treated.
As no large settling tanks are necessary, the turnover time and space
requirements for high gradient magnetic separation are much less than
for other secondary treatments.
• Flow velocity through the matrix can be varied over fairly wide ranges
without substantial changes in effluent quality. Compensation for greatly
increased flow velocities can be achieved by increased concentrations of
polyelectrolyte and magnetite and higher magnetic fields.
• Surge flows can be handled in the above manner and by putting additional
separators into service. Residence times of as little as three minutes
are necessary for adequate flocculation and seeding.
• Matrix loadings of about 0.5 gram of solids/gram of matrix fiber can be
achieved without significantly affecting effluent quality. Filtration
duty cycles exceeding 90% are readily attainable.
• High gradient magnetic separation provides much greater flexibility in
adjustment to large variations in flow rate and influent character than
conventional systems. High gradient magnetic separation is well suited
to automatic operation and produces an effluent that approaches the
quality of effluents produced by tertiary treatment systems.
• Estimated capital cost for an integrated wet and dry weather facility is
approximately $107,000/mgd and operating and maintenance costs are
$0.137/1000 gal. The high gradient magnetic separation capital costs
for an integrated facility are approximately 40% lower than comparative
physical-chemical treatment. Estimated operation and maintenance costs
are approximately 20% lower than physical-chemical treatment processing.
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SECTION II
RECOMMENDATIONS
SUMMARY
On-site operation of pilot plant at existing storm overflow treatment
facility.
Design and construction of demonstration scale integrated dry and wet
weather treatment facility (0.5-2.0 mgd) .
Long term operation (6 - 12 month) of demonstration scale system to
evaluate system performance.
Design and construction of full-scale integrated dry and wet weather
treatment
DETAILED RECOMMENDATIONS
Phase I - Continued Testing on Existing Pilot Plant
A. Using one storm batch collected from Cottage Farm Station (or in the
event of a dry spell, dry weather flow from a sewage treatment plant),
the following should be determined:
1. Maximum permissible matrix loadings over a range of at least
3 different magnetite seed to solids ratios.
2. Maximum matrix loading as a function of different matrix con-
struction designs.
3. Upper limit of flow velocity through matrix.
4. Residence time required after each flocculant addition.
5. Effect of simultaneous flocculant additions as well as different
addition sequences.
Phase II - On-site Pilot Plant Evaluation
A. Tests at Cottage Farm Station and/or other locality (such as Water-
bury, CT) .
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1. Run the pilot plant for the duration of a storm flow.
2. Finish any testing not completed in Phase I.
3. Determine the effect of different backflushing techniques on
effluent quality.
4. Determine minimum backflush volume required for satisfactory
matrix flush.
5. Evaluate long term cleaning and replacement requirement for
matrix.
6. Evaluate characteristics of sludge obtained during preceding
testing.
7. Run system for the duration of one storm with as few changes as
necessary in operation to evaluate long-term operation. Par-
ticular attention should be directed to the "first flush" of
storm flow.
B. Storm flow profile testing (at Cottage Farm Station and/or other
locality).
1. Run pilot plant over the duration of 2 storms profiling pilot
plant flowrate to storm flow. As flow increases, an additional
magnetic separator will be brought on-stream to increase capacity.
C. Pre-engineering and budgetary estimate for demonstration scale inte-
grated wet and dry weather treatment facility.
Phase III - Additional Testing, Demonstration Scale Treatment Facility
Engineering
A. Testing at Cottage Farm or other locality.
1. Investigate the use of treated water for backflushing.
2. Additional testing suggested from Phases I and II.
B. Testing at an EPA pilot plant location in conjunction with EPA
personnel.
C. Revise (if necessary) pre-engineering and budgetary estimate for a
demonstration scale integrated wet and dry weather treatment plant.
Phase IV - Demonstration Scale Integrated Wet & Dry Weather Treatment Facility
A. Construct demonstration treatment plant.
B. Design and conduct test program to evaluate system performance over
(6-12 month) period.
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Phase V - Construct Full-Scale Integrated Wet & Dry Weather Treatment Facility
The testing should include but not be limited to the studies described above.
It is expected that Phases I and II will show the need for additional study of
some parameters. The execution of the present study (#68-03-2218) has shown
that the suspended solids removals were also representative of the BOD^, COD
and bacteria removal results obtained. Thus it is suggested that for the bulk
of the testing in this recommended program only suspended solids and turbidity
tests be regularly performed. Other analyses such as BODr, COD, heavy metals,
coliform, phosphate, etc., should be performed for selected samples only.
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SECTION III
SUMMARY
High gradient magnetic separation has been tested for treatment of
combined storm overflows. The data show that this process is highly effec-
tive for the removal of suspended solids, turbidity, apparent color, BOD5
and fecal coliform bacteria. These removals can be achieved at high process
flow velocities in a single pass through a high gradient magnetic separator.
Results show this technique to substantially surpass present methods of
secondary treatment in effluent quality. Furthermore, estimated cost com-
parisons for similar capacity systems show that high gradient magnetic
separation is economically competitive. Thus, it appears from the present
study that the high gradient magnetic separation process can purify CSO more
effectively than can any other secondary-type treatment.
OPTIMAL PERFORMANCE
The table below shows data from a continuous pilot test on CSO in which
estimated optimal conditions were set and unchanged over a period of approxi-
mately one hour of running time. Ten grab samples were taken (one each from
ten consecutive cycles) during this interval for analysis.
TABLE III - 1
FEED
Average
(# tests)
Range
TREATED
Average
(# tests)
Range
AVERAGE
% REMOVAL
SUSPENDED
SOLIDS
(mg/1)
460
(3)
400-520
6.0
(9)
4.1-9.1
98 . 7%
APPARENT
COLOR
(PCU)
650
(3)
600-800
47
(10)
41-53
92.8%
TURBIDIITY
(FTU)
230
(3)
200-250
8
(10)
8-11
96.3%
FECAL
COLIFORM
(cells/100 ml)
3. 6x10 7
(4)
2.0-5.0x10
5.3xl04
(6) 4
1.5-13x10
99.85%
TOTAL
BOD 5
(mg/D
>79
(2)
>75-83
6.0
(4)
5.2-7.0
>92%
COD
(mg/D
410
(2)
395-425
106
(5)
92.7-138
74%
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SUMMARIZED AVERAGE DATA
The tables shown below give averages for all tests performed throughout
the project (tables in Appendix A break down data into separate CSO and raw
sewage samples). These data necessarily include many non-optimized runs, as
the objective of these tests was to vary certain parameters over wide ranges
to determine best running conditions and relative importances of these vari-
ables. Thus the following averages are underestimates of the achievable
effectiveness of magnetic separation.
Solids Removal
The results of the tests described herein clearly show that high gradient
magnetic separation is a highly effective solids removal means for combined
sewer overflow and raw sewage. Average percent removals obtained from all
bench and pilot plant tests combined are listed below:
TABLE III-2
CSO SEWAGE
% REMOVAL % REMOVAL
Suspended Solids 95 91
(Nonfiltrable Residue)
Settleable Solids 99+ 99+
Apparent Color 87 82
Turbidity 93 88
Biological Material Removal
The efficiency of removal of biological organisms such as bacteria, algae
and viruses is very high. Listed below are combined bench and pilot plant
results achieved for these materials:
TABLE III - 3
AVERAGE
% REMOVAL
Total Coliform Bacteria on EMB agar at 37°C 99.3
Fecal Coliform on EMB agar at 37°C 99.2
(2)
Algae(1) 99.9
Virus, Bacteriophage T ^~' 100
Virus, Polio* 99-100
The total biochemical oxygen demand of the feed was reduced significantly.
An average reduction of greater than 92% was achieved.
* Data from Bitton (See Table IV-4) and Metcalf (See Table IV-5)
7
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Removal of Chemical Species
The seeded high gradient magnetic separation treatment reduced the total
chemical oxygen demand of CSO and sewage samples by an average of 74%.
Removal of heavy metal species was similarly excellent. Average reductions
observed for various heavy metals are listed below:
TABLE III - 4
AVERAGE
METAL % REDUCTION (Range)
Cd > 43%
Cr > 41%
Cu 53%
Pb (0-67%)
Hg > 71%
Ni (0-67%)
Zn 84%
REMOVAL EFFECTIVENESS IN COMPARISON TO CONVENTIONAL TREATMENT
The removal efficiencies of SALA seeded water treatment demonstrated in
this study can be compared to those of conventional treatment processes.
Average percent removals for high gradient magnetic separation treatment and
conventional processes for CSO and raw sewage are compared in Tables III-5
and III-6.
PARAMETER RANGES TESTED
The operational parameters considered in this study were concentrations
of seed and flocculants, flow velocity, magnetic field strength, pH, floe
train residence time, and matrix loading. Evaluation of the relative impor-
tance of each parameter was made by considering effects of parameter change on
percent removal of suspended solids, color, turbidity, bacteria, BOD and COD.
Operational parameters were varied over the following ranges:
Applied Magnetic Field: 0.1 to 1.9 kG
Flow Velocity: 60 to 300 m/hr
Alum Concentration: 0 to 200 mg/1
Seed (Magnetite) Concentration: 50 to 5000 mg/1
Polyelectrolyte (Betz 1150) Concentration: 0 to 3.0 mg/1
pH: 4.5 to 7.5
Matrix Loading: 0,01 to 1.0 g solids/g matrix
Floe Chain Residence Time: 1 to 10 min
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TABLE III - 5
RELATIVE EFFICIENCIES OF CSO TREATMENT OPERATIONS
% Removal
(3)
TREATMENT PROCESS
SUSPENDED SOLIDS BOD5
(TOTAL)
COD
COLIFORM
BACTERIA
High Gradient
Magnetic Separation*
Rotating Biological
Contactor
92-98
70
90-98
54
70-85
99-99.99
Contact Stabilization
High Rate Trickling
Filtration
Treatment Lagoon
Chemical Clarification
Dissolved Air Flotation
with Fine Screening
Fine Screening
(4)
Micro straining
Sedimentation
Dual Media Filtration
with Polyelectrolyte(5)
92
65
(-4)-92
90-98
56-77
35-40
70
60
36-92
83
65
27-91
70-80
41-57 41-45
15
50 37
30
66-79 66-79
83
83
72-96
40-80
10-20
3-99
25-75
* Average percent removal for all Pilot Plant and Bench Tests done on CSO by Sala Magnetics.
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TABLE III - 6
RELATIVE EFFICIENCIES OF SEWAGE TREATMENT OPERATION AND PROCESSES *
% Removal
TREATMENT PROCESS
High Gradient Magnetic
Separation **
Chlorination of Raw or
Settled Sewage
Plain Sedimentation
Chemical Precipitation
Trickling Filtration
SUSPENDED
SOLIDS
88-95
40-70
70-90
50-92
COD COLIFORM
BACTERIA
60-75 99-99.9
90-95
20-35 35-75
40-70 40-80
50-80 90-95
Preceded and Followed
by Plain Sedimentation
Activated Sludge Treatment
55-95
70-80
90-98
* G.M. Fair, J.C. Geyer, and D.A. Okun, Water Purification and Water
Treatment and Disposal, Vol. 2, John Wiley & Sons, New York, 1968,
pp. 21-72.
** Average percent removals for all Pilot Plant and Bench Tests done
on raw sewage by Sala Magnetics.
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Those variables found to be most sensitive to change for good removal
efficiencies in early bench tests were explored in more detail in the
later pilot plant runs and bench tests.
RELATIVE IMPORTANCES, SENSITIVITIES AND INTERACTIONS OF PARAMETERS
The two parameters having the most relative importance on removal
efficiency are coagulant (alum) concentration and pH. For each sample
collected, a slightly different concentration of alum is necessary for
optimal flocculation. This is explained both by the differences in" pH
of the individual samples and by the character and amount of solids
loading. Thus alum is a quite sensitive parameter requiring precise
dosing for good flocculation.
Required polyelectrolyte concentrations vary much less than alum, and
polyelectrolyte can be omitted altogether for low flow rates, as its chief
value is in bridging and strengthening already existing alum-solid aggregates.
Optimum pH likewise seems to vary not only with the nature of the waste
(bacterial polymers present, etc.), but also with the relative amounts of
alum and polyelectrolyte being used, since these agents have optimum floc-
culation pHs of -i/ pH6 and rv. pH8 respectively. At higher processing rates
however, use of polyelectrolyte may be necessary for successful magnetic
separation in order to compensate for floe disruption caused by higher
hydrodynamic shear forces.
Matrix loading is also an important parameter, as it is directly related
to the influent solids loading and the magnetic seed concentration used
(which in turn are related to each other). Breakthrough occurs when the
magnetic matrix is overloaded with sludge. Thus, the flushing interval
(cycle time) must be varied with influent solids load as well as with pro-
cess flow rate. Flow velocity itself seems to be a relatively insensitive
parameter within our test range except when matrix loading or low polyelectro-
lyte concentrations are involved. Changes in efficiency of separation of
only a few percentage points were observed over the velocities tested.
Magnetite concentration, magnetic field strength and floe chain residence
time are relatively insensitive parameters above certain minimum values.
Magnetite concentrations necessarily depend directly on the solids present in
the feed. A ratio of 1:1 produced good separation. Magnetic fields as low
as 0.5 kG were sufficient on all feeds tested, but it can be assumed that at
higher flow velocities, where shearing effects are more critical, higher
fields may be necessary. Mixing times necessary for good flocculation were
short (on the order of three minutes). Longer mixing times (up to ten
minutes) did not give significantly better separation.
11
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SECTION IV
INTRODUCTION
OVERVIEW OF HIGH GRADIENT MAGNETIC SEPARATION
Magnetic separation techniques have been used since the nineteenth
century to remove tramp iron and to concentrate iron ores. A variety of
conventional magnetic separation devices are in wide use today. These
devices generally separate relatively coarse particles of highly magnetic
material containing large amounts of iron from non-magnetic media.
In recent years magnetic devices have been developed which are capable
of separating even weakly magnetic materials of micron size at inherently
high flow rates. These so-called "high gradient magnetic separators" have
been designed to maximize the magnetic forces on fine, paramagnetic materials.
They are capable of efficient separation of even weakly magnetic suspended
solids or precipitates for which conventional magnetic separation techniques
are ineffective. The separations may be carried out economically and at
process rates of up to several hundred gpm/ft -
For normally non-magnetic colloidal material in polluted water the
addition of small quantities of magnetic iron oxide (magnetite) renders
these colloids sufficiently magnetic to be removed by high gradient magnetic
separators. The machines provide the rapid filtration of many pollutants
from water, with a small expenditure of energy. Removal is much more effi-
cient than with sedimentation because the magnetic forces on fine particles
may be many times greater than gravitational forces. This technology has
a high potential for application to water pollution control.
High gradient magnetic separation is currently used in the kaolin clay
industry for the removal of weakly magnetic impurities less than 2 microns
in diameter from clay. High gradient magnetic separators treating up to
60 tons per hour of dry clay as a 30 percent slurry are industrial-size
units. A Sala pilot plant capable of processing up to 5 tph of kaolin
slurry is shown in Figure IV-1. These high gradient magnetic separators
are the result of the development of a filamentary ferromagnetic matrix and
a large volume high field magnet. This combination of an efficient magnet
and high gradient matrix permits the economical production of strong magnetic
forces over a large surface area in the active volume of the separator.
12
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FIGURE IV-1 SALA 5 TPH KAOLIN CLAY PILOT PLANT
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PRINCIPLES OF HIGH GRADIENT MAGNETIC FILTRATION
Magnetic and Competing Forces
High gradient magnetic separators, like all magnetic separators, utilize
the interaction of magnetic and competing forces on a mixture of magnetic and
non-magnetic particles to provide separation based on the magnetic susceptibil-
ities of the particles. The magnetic forces of attraction in a high gradient
magnetic separator hold the magnetic particles to the edges of the matrix
fibers while the competing hydrodynamic forces carry the fluid and non-mag-
netic particles through the separator. For small particles the forces of
hydrodynamic drag are larger than gravitational forces, and increase with
slurry velocity in the separator. The magnetic forces necessary to trap
these particles must, therefore, be large.
Maximizing the Magnetic Forces
High gradient magnetic separators effectively maximize the magnetic
force on even weakly magnetic particles(6,7). The magnetic force (F ) on
a particles is given by the following expression: m
F = vM grad H
m
where v_ is the volume of the particle, M is its magnetization, and grad H
is the magnetic field gradient that acts on the particle. The magnetic field
gradient appears in the expression for magnetic force for the following
reason. Placed in a magnetic field, all particles develop north and south
poles at either end as shown in Figure IV-2. In a uniform field the net
force on a particle will be zero since the field exerts an equal and opposite
force on either end of the particle. In a gradient magnetic field, however,
the force exerted by the stronger field at one end of the particle will pro-
duce a net force on the particle. Therefore, the larger the change in field
across the particle (magnetic field gradient), the greater the force on the
particle.
The magnetization of ferromagnetic fibers like those in the high gradient
magnetic separator matrix produces extremely high magnetic field gradients. It
turns out that the greatest force is produced on the particles when the
diameter of the magnetized wire is approximately the same size as the particle
to be trapped. This matching of the fiber diameter to the particle size is
utilized in high gradient magnetic separators to produce extremely large
forces on even weakly magnetic particles.
The Ferromagnetic Matrix
In order to produce strong magnetic forces over a practical surface
area, a filamentary ferromagnetic matrix magnetized by a strong applied
field is used(°'. The effective trapping volume of this type of matrix is
many times larger than that achieved by the use of tacks, balls, or other
small ferromagnetic objects which also produce large field gradients when
magnetized. As shown schematically in Figure IV-2, the introduction of the
14
-------
MAGNETIC FORCE
FM = VM grad H
L magnetic field
gradient
^particle magnetization
L particle volume
COMPETING FORCE
hydrodynamic drag
FC
FIGURE IV-2
CUTAWAY VIEW OF HIGH GRADIENT MAGNETIC SEPARATOR
Lslurry velocity
-particle diameter
slurry viscosity
15
-------
FIGURE IV-3 MATRIX MATERIALS USED IN HIGH GRADIENT MAGNETIC SEPARATORS
-------
ferromagnetic matrix into the uniform magnetic field produced by the electro-
magnets in the high gradient magnetic separator, produces a multitude of
high gradient strong forces within the volume of the separator. A strong
applied field is required to magnetize these fibers, and when this field
is turned off, the residual magnetization of the fibers is very low. For
this reason even strongly magnetic particles are easily washed out when the
applied field is reduced to zero. Typical matrix materials are shown in
Figure IV-3.
Production of Strong Magnetic Fields
The ferromagnetic matrix is a relatively difficult magnetic structure
to magnetize—that is, a large strong applied magnetic field is required to
produce high field gradients along the matrix filament edges. The magnetic
fields in conventional magnetic separation devices are not sufficient to
magnetize the ferromagnetic matrix. Therefore, practical realization of
high gradient magnetic separation depends as much on the production of an
economical, intense magnetic field as it does on the ferromagnetic matrix.
It is useful to compare the design of prior art magnets with those used
in high gradient magnetic separators. Figure IV-4A shows a magnetic circuit
commonly used for producing strong magnetic fields in conventional and some
competing high intensity magnetic separators. The magnetic field in the
working volume is produced by magnetic poles in the iron on either side of
the gap. The electromagnetic energizing coils are placed on vertical legs
of the magnet circuit in order to magnetize the iron. Much of the field
produced by the coils in iron, however, never reaches the working volume but
leaks around it through magnetic short circuits. The electromagnetic coils
contribute nothing directly to the magnetic field of the working volume
since they are placed away from the working volume on the yoke of the magnet.
By contrast, in Figure IV-4B the magnetic circuit of the Sala design
is shown superimposed on the prior art circuit. The electromagnetic coil
is placed directly around the working volume where it contributes directly
to the field within that volume as well as to the magnetization of the iron
poles on either side of the working volume. A small iron return path
around the Sala coil further increases the efficiency of the circuit. It is
clear that considerable savings in iron have been achieved for the same
working volume. In addition, the magnetic field produced in the new magnet
is considerably more powerful for the same input of electrical energy than
in prior art devices.
The Operating Variables of the Separator
The efficiency of magnetic particle trapping in a high gradient magnetic
separator depends heavily upon the operating variables of the separator as
well as the size and magnetic susceptibility of the particles. The operating
variables are: the strength of the applied magnetic field; the velocity of
the feed passing through the matrix; and the ratio of the feed material
weight (percent of solids) to the working volume of the separator. The
recovery of the magnetic particles increases with an increasing magnetic
17
-------
WORKING VOLUME
CO
WORKING VOLUME
RETURN FRAME OR CORE
NERCI2ING COILS
SALA MAGNETIC CIRCUIT
(Prcor irl tircull Irom
ICTURN FRAME OR CORE
ri*r Art Hi|Mt
FIGURE IV-4A
FIGURE IV-4B
COMPARISON OF PRIOR ART AND SALA HIGH GRADIENT MAGNETIC SEPARATORS
-------
field because the magnetic forces are stronger. The recovery of the magnetic
particles decreases with increasing feed flow velocity because the competing
hydrodynamic drag forces are larger. The recovery of magnetic particles
decreases with increased matrix loading since high gradient trapping sites
within the matrix volume become filled, leaving fewer available trapping
sites. The optimization of the operating variables described here is
important since these variables significantly affect the capital and pro-
cessing costs in the practical use of high gradient magnetic separators.
HIGH GRADIENT MAGNETIC SEPARATORS
In its simplest form, the high gradient magnetic separator consists of
a canister packed with a fibrous ferromagnetic material and magnetized by
a strong external magnetic field. A schematic cross-section of a static
high gradient magnetic separator is shown in Figure IV-5. The magnetic
matrix shown at the center is magnetized by the coils (indicated by crosses)
which surround the canister. An iron frame increases the efficiency of the
electromagnetic coils. The device operates in a sequence of feed and flush
modes. A feed slurry containing the particles to be separated is passed
through the device with valves 1 and 3 open. The magnetic particles are
trapped on the edges of the magnetized fibers while the non-magnetic particles
and slurry fluid pass easily through the canister. The matrix offers only
a small hydraulic resistance to the feed flow, occupying less than 5% of the
canister volume (95% void volume). When the matrix has become loaded with
magnetic particles, valves 1 and 3 are closed and the magnetic particles
are easily washed from the matrix by reducing the magnetic field to zero and
opening valves 2 and 4 to permit backflushing. High gradient magnetic
separators of this type, termed "static," "batch," or "cyclic" devices are
used to process fluids and minerals containing a low percentage of magnetic
impurity. Cyclic devices may be operated automatically and quasi-continuously
by use of feed surge tanks. Separators of this design are useful for water
treatment.
HIGH GRADIENT MAGNETIC FILTRATION TECHNIQUES IN WATER TREATMENT
The use of high gradient magnetic separation or filtration in water
treatment may be accomplished in two ways depending on the nature of the
contaminants in the water. For waters contaminated by magnetic suspended
solids, such as steel mill waste waters and the corrosion products of boiler
waters, high gradient magnetic filtration may be used alone to effectively
remove these particles ("direct filtration").
High gradient magnetic separation may also be used to remove non-magnetic
contaminants from water. This is accomplished by binding finely divided mag-
netic seed particles to the non-magnetic contaminants, thus creating a "mag-
netic handle" ("indirect filtration" or "seeded water treatment").
Binding of the magnetic seed is accomplished in two general ways:
adsorption of the contaminant to magnetic seed and chemical coagulation.
Particles ranging in size from soluble through settleable (>0.001 y) may be
removed with this process.
19
-------
FEED IN
FIGURE IV-5
CROSS SECTION OF STATIC
HIGH GRADIENT MAGNETIC
SEPARATOR
FLUSH OUT
X X
MATRIX-*!
SALA-HGMS™
MAGNETIC
SEPARATOR
FLUSH IN
.SAMPLE COLLECTION
20
-------
In the adsorption mechanism, magnetic seed can both adsorb to larger
particles and act as an adsorbent for smaller particles in the water. Ad-
sorption of smaller particles to magnetite used as the magnetic seed has been
demonstrated in the concentration of viruses by high gradient magnetic sepa-
ration*' ' . The mechanisms of adsorption are not known but postulated
mechanisms include chelation, as is probably the case with humic acid derived
colorants, and poly or covalent surface bonding, which is likely in the adsorp-
tion of bacteria and viruses. Other mechanisms are possible.
The more versatile and more practical technique is chemical coagulation
of the magnetic seed and contaminants into aggregates. Coagulation using an
Al+3, Fe"1"^ or Ca coagulant generally will result in the production of
somewhat fragile aggregates. These can be very successfully removed by high
gradient magnetic separators under low shear force conditions (low unit flow
rates). When an organic polyelectrolyte coagulant is also added, the inter-
particle bridging provided by the polyelectrolyte greatly strengthens the
aggregates. Floes produced by metal ions and polyelectrolyte coagulants
will withstand high shear forces inherent in high processing rates.
Personal Communication, T.A. Metcalf, Chairman, Dept. of Microbiology,
University of New Hampshire
21
-------
APPLICATIONS OF HIGH GRADIENT MAGNETIC SEPARATION TO WATER TREATMENT
Suspended Solids Removal
Steel Mill Waste and Process Waters—
Treatment of steel mill waters involves the direct filtration of finely
divided, strongly magnetic suspended solids. Non-magnetic suspended con-
taminants such as tramp oil are naturally seeded by the magnetic particles.
As a result, they are also removed without the addition of further seed or
chemical media.
Table IV-1 presents some of the results obtained in treating steel mill
process and waste waters^9). Sala Magnetics, Inc., has built a 500 gpm pilot
plant for this application.
Other—
High gradient magnetic separation has many other applications to sus-
pended solids removal. Treatment of boiler feed waters'10 and removal of
radioactive corrosion products from nuclear reactor primary coolant loops
(AECL-White Shell) are examples of direct filtration applications now in
use. Seeded water treatment of municipal and industrial waste waters is of
great potential importance in the removal of suspended solids as well.
Heavy Metals Removal
The release of heavy metals into the environment by industry or in
agricultural practice poses both a health hazard to humans and causes exten-
sive ecological damage. The hazard is especially great because the micro-
flora are unable to excrete these pollutants which are consequently con-
centrated up the food chain. The efficient removal of heavy metals from
point sources is of prime concern for the maintenance of pollution-free
natural waters.
A process developed by Nippon Electric Company of Japan consists of
treating waste water with ferrous sulfate, neutralizing with sodium hydroxide
and oxidizing with air under specific conditions^- ^ . As a result, a ferrite
sediment in which the heavy metals and iron have been co-precipitated is
obtained. This magnetic sediment is separated by magnetic filtration. The
results obtained with this process are shown in Table IV-2.
The removal of heavy metals by precipitation and direct high gradient
magnetic filtration has also been observed. Table IV-3 shows the removal
of nickel and copper from precipitated plating waste waters by direct
high gradient magnetic separation.
Bacteria Removal
Finely divided magnetite adsorbs well to bacterial cell membranes.
When raw sewage, secondary treated effluent, or another polluted water is
seeded with magnetite, the biomass is amenable to removal by high gradient
magnetic separation'-^,13,14) .
22
-------
TABLE IV - 1
Results Obtained Using High Gradient Magnetic Separation
To Treat Steel Mill Process and Waste Waters^
BF Scrubber
Water
SUSPENDED SOLIDS
FEED TREATED
(mg/1) (mg/1)
1340 13
582 1.2
MAGNETIC
FIELD
(kG)
10
5
FLOW
VELOCITY
(m/min)
3.4
1.32
NUMBER
OF
PASSES
2
2
Vacuum & Elec-
tric Furnace
309
2.5
10
2.1
BOF Scrubber
Water
Hot Rolling
Mill Scale Pit*
4500
4500
46
168
<1
10
4
12
9.6
4.6
5
2
2.5
5
4.5
4.5
1
1
1
1
Cold Rolling
Mill Water
46.7
14
11.5
0.74
^Personal communication with John Harland, Sala Magnetics (1976)
23
-------
TABLE IV - 2
Concentration of Metal Ions in Influent and Effluent^ '
Metal
Hg
Cd
Cu
Zn
Cr
Ni
Mn
Fe
Bi
Pb
Influent
(mg/1)
7.4
240
10
18
10
1000
12
600
240
475
TABLE IV - 3
Effluent
(mg/1)
0.001
0.008
0.01
0.016
> 0.01
0.2
0.007
0.06
0.1
0.01
Treatment of Plating Waste Water*
Sample
Feed
S-5
S-7
S-8
Cu Ni
(mg/1) (mg/1)
3.0 5.3
0.30 1.5 100
0.23 2.8 200
0.16 0.85 No
Treatment pH
mg/1 FeCl3 8.5
mg/1 Magnetite 8.5
Additives 10.1
Sala Magnetics' Data
24
-------
Mitchell and co-workers(14) described a removal of between 90 and 99%
of the bacteria from polluted water seeded with magnetite and passed through
a high gradient magnetic filter. More recent studies in Mitchell's labor-
atory have yielded 99.9% removal of bacteria from seeded raw sewage.
Algae Removal
Algae are removed by high gradient magnetic separation as efficiently
as bacteria. In batch experiments all of the algal cells in contaminated
water were caught on the high gradient magnetic filter(1). The high degree
of efficiency in removing algal cells probably reflects their large size and
therefore the high concentration of magnetite adsorbed to their surfaces.
Virus Removal
(2)
Bitton and Mitchell have carried out an extensive study of magnetic
separation of viruses from water. Ninety-five percent of the viruses were
removed by high gradient magnetic filtration following ten minutes of contact
time with magnetite. A concentration of 250 mg/1 of magnetite was sufficient
to yield maximal removal. The addition of calcium chloride as a bridge be-
tween the virus and magnetite improved separation. The process provides 100%
removal for as few as 30 and as many as 14,000 virus units (PFU) per ml of
water.
Recent unpublished data from Bitton's laboratory show the efficiency of
removal of polio virus using a SALA-HGMF virus concentrator. Table IV-4
shows these results. Between 99 and 100 percent removal of polio virus was
achieved using high gradient magnetic separation.
Similar results have been obtained by Metcalf at much higher concen-
trations of polio virus. The enclosed letter (Table IV-5) indicates that
he found high gradient magnetic separation to be very efficient in the
removal of polio virus from water.
Dissolved Phosphorus Removal
Several methods are available for the removal of phosphorus from sewage.
They depend on the coagulation of the phosphates with lime or alum. The
coagulated phosphates are usually sedimented in ponds. Disadvantages of the
sedimentation process include the requirement of time and space and the
inability to remove finely suspended particles. By comparison, high gradient
magnetic separation of phosphates is very rapid and removes even verv finely
suspended phosphate precipitates with systems requiring a small area^ ' .
Color and Turbidity Removal
Both colored materials and suspended solids associate well with magnetite
making them amenable to removal by high gradient magnetic separation. Sala
has carried out a series of bench tests on several pulp and paper mill ef-
fluents for a major U.S. paper company with excellent results. These results
show significant reductions in color and turbidity.
25
-------
TABLE IV - 4
Removal of Polio Virus from Water Using
High Gradient Magnetic Separation
Feed
Virus Concentration Removal
in PFU/ml Efficiency (%)
1025 100
1300 99
1250 100
The magnetite concentration in these bench tests was 1000 mg/1.
CaCl? was used as a binder.
Data courtesy of Professor G. Bitton, Department of Environmental
Engineering, University of Florida.
26
-------
UniUERSlTl] OF T1EU;
DURHAm, TIEU; HAmPSHlRE 03824
TABLE IV-5
COLLEGE OF LIBERAL ARTS
Department of Microbiology
Spaulding Life Science Building
March 18, 1976
Mr. Don Dallas
Sala Magnetics
169 Bent Street
Cambridge, Massachusetts 02138
Dear Mr. Dallas:
Magnetic separation of virus from aqueous suspensions using
permanent-type magnets (MIT model borrowed from David Kelland,
and Sala Magnetics 2 kilogauss model) has proven technically
feasible in studies carried out in the Virus Laboratory, Univer-
sity of New Hampshire. Studies using poliovirus type 2, have
demonstrated the ability of these magnets to remove magentite-
adsorbed virus within steel wool matrices subject to the magnetic
force field. Imposition of appropriate parameters of pH, magnetite
concentration, adsorptive conditions, steel wool matrices, magnetic
field intensity and flow rates can result in complete removal of up
to 1x10° plaque forming units of virus from 1 liter volumes under
controlled laboratory conditions.
My current major interest in magnetic separation technics con-
cerns their application to the recovery of enteric viruses from
wastewater samples. This calls not only for an initial removal of
virus from wastewater but also a subsequent recovery of virus from
the steel wool matrix within the magnetic force field. Research
goals currently are addressed to two fundamental objectives. The
first is how best to efficiently and economically remove virus
from large volumes of dirty wastewater, entrapping virus within
collecting matrices. The second relates to a determination of con-
ditions productive of a maximum recovery of virus from collecting
matrices.
Study data suggest that magnetic separation technics can be ap-
plied successfully to the removal from relatively clean waters of
at least the enteroviruses. There is no obvious reason at the
moment to doubt the ability of the separation technology to cope
successfully with other members of the enteric viruses also alth'ough
I personally have not looked at any virus other than poliovirus.
There are many details to be determined of course for waters of
varying composition and quality, and I am not prepared to comment
on removal efficiency but I do believe the technology is sufficiently
promising at the moment to justify further research.
Sincerely yours ,
*'- ). __• ," ~
""v^, '//(aA;^.
T. G. Metdalf "
Professor of Microbiology
27
-------
OBJECTIVES OF THE STUDY
The objectives of this study were to:
1. Optimize the conditions for the removal of solids from
combined storm overflows using bench-type tests.
2. Demonstrate effectiveness of a pilot scale high gradient
magnetic separation treatment system for treating combined
sewer overflows and storm water and to use this information
as a basis for larger scale design.
3. Develop basic design criteria and operating characteristics
for this system that can be translated into a larger scale.
4. Determine projected capital and operating costs based on the
demonstrated treatment system.
5. Investigate the feasibility of high gradient magnetic separation
systems for integrated wet and dry weather systems.
28
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SECTION V
EXPERIMENTAL DESIGN
BENCH TEST APPARATUS DESIGN
The basic concept in bench testing is to use a simple jar test (modified
by adding seed and flocculation steps) which can be used to set operational
parameters for larger systems. The installation used in initial testing is
shown in Figure V-l. A SALA-HGMS magnetic separator Model 5-18-2 identical
to that in the continuous pilot plant was used. Backflushing was accomplished
using line pressure (50 psig) tap water.
CSO samples were placed in 2-liter beakers and stirred with a paddle
stirrer used in standard jar testing. Flocculated samples were poured into
the funnel at the separation system top and routed through the pre-flooded
high gradient magnetic separator. Testing showed that a 1.6 liter sample was
too small to yield consistent, accurate results.
The bench test apparatus was modified to accept much larger samples.
A 20 liter hopper was substituted for the original 2 liter funnel. The
hopper was also raised from 40 cm to 55 cm above the high gradient magnetic
separator. Since sample sizes up to 20 liters were to be used, the paddle
stirrer was no longer sufficient and a variable speed stirrer was substituted.
A platform had to be built to allow the transfer of these samples from agi-
tator to hopper. This redesigned bench installation is shown in Figure V-2.
The modified bench test system has been entirely adequate for all evaluations
attempted.
PILOT PLANT APPARATUS
Design
The pilot plant used in these tests and owned by Sala Magnetics, Inc.,
is shown in Figures V-3, V-4 and V-5. It was designed and constructed at
SMI expense to investigate the seeded water treatment technique.
The process flow sheet for the continuous pilot plant is shown in
Figure V-6. As indicated in the flow sheet, the pilot plant contains a
flocculation train in which all necessary chemical additions are made, a
SALA-HGMS magnetic separator and power supply, and a surge tank and thick-
ener to handle the backflushed floes that were trapped in the matrix bed.
An automatic controller sequences the addition and mixing of chemicals,
water movement from tank-to-tank, and the actual filtration and backwash
29
-------
I
FIGURE V-l INITIAL BENCH TEST APPARATUS
30
-------
•I
FIGURE V-2 REDESIGNED BENCH STUDY INSTALLATION
31
-------
U)
Ni
FIGURE V-3 SALA CONTINUOUS PILOT PLANT
-------
: SJ S N M "~i •>. v;
FIGURE V-A PILOT PLANT AUTOMATIC CONTROLLER
33
-------
FIGURE V-5 PILOT PLANT POWER SUPPLY AND MONITORING SYSTEM
-------
CLCAX moctssio
OJ
Ln
THICKENER
CAPACITY : 24O LITIUS PE« W3UR
FIGURE V-6
FLOW SHEET
Seeded Water Treatment Pilot Plant
-------
cycles through the magnet. Untreated feed is pumped from the storage tank
to the first residence tank where the feed is mixed with alum. The magnetite
is added in a second flash mixing tank. Finally, a polyelectrolyte is flash
mixed into the stream to induce bonding among floe particles, bridging them
together into larger agglomerates. The pH is monitored and controlled auto-
matically.
The flocculated feed water is next drawn through the SALA-HGMS high
gradient magnetic separator by a filter pump which is located downstream
from the magnet to avoid floe disruption. Once the filter cycle is com-
pleted the filter pump and the magnet are shut off and the matrix is back-
flushed with high pressure water. The backflush water containing the floes
washed from the matrix filter bed enters a surge tank from which the inte-
grated flow is fed to the thickener.
The pilot plant system is synchronized so that concentrations of
chemicals remain constant throughout the residence chain. The system is
easily adjusted, moreover, to permit a wide range of additions.
Initial testing of CSO on the pilot plant resulted in several problems.
The most significant of these was failure of the valves controlling the flow
to the high gradient magnetic separator. This problem was corrected by the
installation of diaphragm valves rated to the intended service. Clogging of
flow regulating valves was eliminated by 3 stage screening (final stage,
20 mesh) of the influent. Proper metering of flocculants and seed was ensured
by the installation of adjustable metering pumps in place of constant level
tanks.
Bench test experiments indicated that the magnetite and polyelectrolyte
additions would be flash-mixed into the influent stream. Flash-mixing
chambers were installed just before the residence surge tank. During opera-
tion certain components of the pilot plant were discovered to be unnecessary
and were eliminated.
Flexibility and Capacity
Pilot plant operation may be either manually or automatically controlled.
In the automatic operational mode nearly any combination of filter cycle and
backflush can be obtained. The automatic controller is partially interfaced
with process monitoring equipment (pH controller and turbidimeter) and res-
ponds to feedback from those sources. Thus the pilot plant can monitor the
effluent quality and automatically initiate backflush once filtering capacity
of the matrix is reached.
Because the pilot plant was designed to study seeded water treatment, it
was constructed as a very flexible system. The influent flow rate is varied
by valve adjustment. Residence time is varied by changing the number of tanks
in the floe chain. The concentrations of flocculants and seed are easily
adjustable over wide ranges.
36
-------
SECTION VI
METHODS AND PROCEDURES
BENCH TESTS
Test Procedures
The tests performed in the bench study were essentially modified floc-
culation jar tests. The flocculants and seed were added to the CSO samples
while stirring at 200 RPM with a paddle stirrer. Subsequently the mixer
speed was reduced to 90 RPM for the duration of the flocculation. In these
tests, the alum was added first followed by the magnetite seed and poly-
electrolyte.
After flocculation occurred, the sample was transferred to the funnel
feeding into the SALA-HGMS magnetic separator. The matrix volume was kept
full of clean water at the beginning of each bench test so as to ensure
uniform flow velocity through the matrix. The first matrix volume of water
(clear water in matrix at start) to come out of the high gradient magnetic
separator was discarded. The treated CSO was then tested to determine
remaining suspended solids, turbidity, etc.
Scope of Testing
A parametric study was carried out to determine the initial operating
conditions for the continuous pilot plant. The following parameters were
varied over the ranges listed below:
1) Applied Magnetic Field: 0.1 to 1=95 kG
2) Flow Velocities: 60 to 300 m/hr
3) Alum (commercial grade) Concentration: 0 to 200 mg/1
4) Seed: commercial grade Magnetite (Fe,,0,)* Concentration: 50 to
5000 mg/1
5) Polyelectrolyte (Betz 1150) Concentration: 0 to 3.0 mg/1
* Magnetite obtained from Eveleth Taconite Co., Eveleth, Minn. This was
sized, washed and deslimed before use. Size classification chosen was
+5y -40p. This procedure included discarding the fraction larger than
325 mesh (>40p), putting ore into a slurry form and decanting the top
portion after 90 minutes.
37
-------
6) pH (adjustment by NaOH, HC1 reagent grade): 4.5 to 7.5
7) Residence Times: 1 to 10 minutes
All samples were analyzed for suspended solids, apparent color and turbidity.
It was originally intended that all samples be analyzed for settleable solids;
however, these were always immeasurable in the treated samples. Selected
samples were analyzed for filtered and unfiltered BOD5 and COD, fecal and
total coliform and certain trace heavy metals.
PILOT PLANT
Test Procedures
The following procedures were performed during testing on the continuous
pilot plant. Initially, seeded flocculation jar tests were run to determine
the approximate dosages of alum and polyelectrolyte. Flow rates of floc-
culants and seed were adjusted to achieve the desired concentrations. The
influent and effluent flows were then set at the desired rates.
The flocculation residence chain was allowed to stabilize before testing
was begun. Thirty minutes of operation were generally allowed to achieve
stabilization although visually the system seemed stable after 8 minutes.
In addition, twelve minutes or more were allowed for stabilization between
parameter changes. Samples were taken at various points in the filtering
cycle depending upon the test being performed. Samples were then analyzed.
Scope of Testing
The following tests were performed on the continuous pilot plant:
1. Alum, seed and polyelectrolyte concentrations were varied to
compare cost as a function of performance,
2. Matrix loading was varied to determine effective filter cycle
length.
3. Residence times were varied to evaluate system effectiveness
over a range of residence times.
4. Raw sewage was treated to determine the feasibility of using
high gradient magnetic separation for treatment of both wet
and dry weather flows.
5. Magnetic field and flow rate were simultaneously increased to
determine the system's ability to maintain performance level
at increased capacities needed in the case of storm surges
and overflow.
38
-------
ANALYTICAL PROCEDURES USED IN BENCH AND PILOT TESTING
All analyses were performed according to the analytical methods listed
below:
Units
Suspended Solids (Nonfiltrable Residue) - mg/1
Standard Methods #224 C
Turbidity - Standard Methods #163A FTU
Color, Apparent - STORET No. 00080 PCU
Settleable Solids - Standard Methods #224 F ml/1
BOD5 - Standard Methods #219, Probe Method mg/1
COD - Standard Methods #220 mg/1
Fecal Coliform - counts on EMB agar at 37°C # cells/100 ml
Heavy metals - Cd, Pb, Zn, Cr, Ni, Hg, Cu mg/1
SAMPLE COLLECTION
For most of the bench testing work the CSO was collected in five gallon
buckets, up to 60 gallons at a time. This collection method worked well for
the bench test phase as sealed buckets could be transported easily and samples
could be taken at short notice.
When testing was initiated on the continuous pilot plant much larger
sample volumes were required than could be reasonably collected in buckets.
Sampling was arranged with a local septic tank pumping firm. The firm* used
a 1500 gallon vacuum truck with the agreement that the truck tank be rinsed
with hydrant water several times before collection. This large sample was
discharged into 2 large storage tanks (Figure VI-1) equipped with agitation,
aeration and ventilation.
During the course of testing it was discovered that the CSO collected
by the septic tank truck was severely contaminated in spite* of the tank
rinsing. Examination of the tank interior showed that a contaminated sample
would be unavoidable. While the septic tank truck drew a sample, a bucket
sample was taken simultaneously. Comparisons of the two samples, presented
in Table VI-1, showed that severe contamination had resulted from the truck.
After this test all subsequent samples were collected in clean 55 gallon
drums using a portable pump.
One problem that was both anticipated and encountered, was significant
biological growth during storage. In one case (CSO of 12/9/75, Table A-l)
the suspended solids in the feed doubled in 7 days. Since excess biological
* Clearway Sewerage and Drain Service, Inc., Cambridge, MA
39
-------
ff mm wiMia
[**«••• MT CMttM
FIGURE VI-1 STORAGE TANKS FOR CSO SAMPLES
-------
TABLE VI - 1
COMPARISON OF METHODS OF COLLECTION
CSO COLLECTED ON 1/14/76
Feed from Truck*
SUSPENDED
SOLIDS
(mg/1)
APPARENT
COLOR
(PCU)
TURBIDITY
(FTU)
FECAL TOTAL
COLIFORM COLIFORM
(cells/100 ml)
415
1130
350
2.7 x 10
1.6 x 10
Feed from Bucket**
36
120
32
9.3 x 10"
7.7 x 10
* Septic tank pumping truck, after being rinsed several times with hydrant water,
collected a 4000 liter sample of CSO from Cottage Farm.
** A small sample of CSO was collected in buckets simultaneously with septic tank
pumping from same point to check contamination levels of truck collection.
-------
digestion tends to result in a more easily flocculated feed, extended storage
times were avoided. Aeration was necessary to keep the sample from becoming
anaerobic and thus producing a methane safety hazard.
ANALYTICAL LABORATORY FACILITIES
Sala Magnetics, Inc., has equipped and maintains an analytical
laboratory (Figure VI-2) for water and waste analysis. The following
tests (as described in Section VII) were performed in the SMI laboratory:
Suspended Solids
Settleable Solids
Color (Apparent)
Turbidity
BOD , Total
Fecal Coliform
The following tests were performed at outside laboratories:
COD
Heavy metals (quantitative)
42
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FIGURE VI-2 WATER ANALYSIS LABORATORY AT SALA MAGNETICS, INC.
-------
SECTION VII
TESTING PROGRAMS PERFORMED
BENCH TESTING PERFORMED
On 12/9/75 a CSO sample was drawn from the Cottage Farm facility. The
facility's activation was a small flow of short duration. Suspended solids
in this CSO were very low and settleable solids were immeasurable. All para-
meters of the revised bench study were varied independently using 1.6 liter
samples. Listed in Table A-l are the combined results obtained from testing
this CSO sample (without parameter optimization). Detailed data for this and
other storms are contained in Appendix A and discussed in Section VIII.
Due to both the low suspended solids loading in this particular CSO batch
and the sample size used, the magnetic filtration matrix loading was rather
low (0.012 g/g matrix fiber). At this low matrix loading, mechanical trapping
could contribute significantly to the actual filtration efficiency. A test
conducted at zero magnetic field showed that a sample of approximately 5
liters was required to minimize these effects. At this low solids loading
several samples were flocculated under identical conditions in 1.6 liter
aliquots. These were passed in succession through the high gradient magnetic
separator set at 0 kG magnetic field. Since there was no magnetic field
operating to retain seeded floes in the matrix, the degree to which floes
were mechanically trapped in the matrix could be determined. For the first
liter of sample passed through the matrix, nearly all of the floes were re-
tained by mechanical trapping. After two additional liters had passed, ap-
proximately 50% of the floes were caught. Nearly all of the floes passed
through the matrix after feeding 3 to 3.5 liters of sample. The matrix
loadings after passing the aforementioned volumes through the separator mag-
net are listed below:
Volume
Flow Velocity of 120 m/hr
liter
Matrix Loading
0.007 g/g matrix
0.015
0.023
0.035
It was also observed that the flow velocity used had a large effect on floe
retention due to mechanical trapping. At low flow rates (120 m/hr or less)
this trapping was most severe. Higher flow rates showed reduced levels of
mechanical trapping. The relationship of hydrodynamic drag forces to flow
velocity explains this variation. Subsequent jar tests were run with suf-
44
-------
ficiently large samples to get satisfactory matrix loadings (0.03 g solids/g
matrix fiber).
On 12/19/75 a small CSO sample was collected from Cottage Farm to verify
the performance of high gradient magnetic separation treatment at higher
matrix loadings. The combined results obtained from this testing are listed
in Table A-2. Matrix loading reached 0.16 g solids/g matrix in this test, a
loading high enough to render mechanical trapping a negligible part of the
actual filtration.
Pump failure at Deer Island Sewage Treatment plant resulted in Cottage
Farm handling raw sewage on 12/26/75. A limited evaluation of the SALA-HGMS
Magnetic Separation Water Treatment System was conducted on this sewage; the
combined results are tabulated in Table A-3.
Melting snow on 12/31/75 caused activation of the Cottage Farm facility;
and a 700 gallon sample was taken. Flow velocity and magnetite concentration
were varied. Bench treatment of this CSO has yielded the combined results
shown in Table A-4. It should be noted that the melt waters tested (samples
of 12/31/75 and 3/17/76) were both heavily laden with solids and bacteria.
In both cases exceptionally good magnetic purification was possible, indicat-
ing the high gradient magnetic separator's ability to deal with such highly
polluted waters in a single pass through the magnet.
On 1/28/76 a small sample (40 liters) of CSO was collected from Cottage
Farm. Bench tests were conducted using a 1.0 kG permanent magnet on 4 liter
samples. Since the effective length of this separator was only 3 inches
(compared with 6%" for our electromagnets) this small sample size was suf-
ficient to provide satisfactory matrix loading (0.03-0.11 g solids/g matrix
fiber). A series of 9 aliquots were tested, 3 data points each for magnetite
seed, alum and polyelectrolyte concentrations. The results are shown in
Table A-5. The lower removal efficiencies compared to tests with electro-
magnets are attributed to the reduced magnetized matrix span through which
the sample was passed. Flushing of this system was also more difficult and
may have been a source of error (the canister had to be removed and hand
flushed after each test).
On 3/1/76 a small sample of raw sewage was collected from Deer Island
Sewage Treatment Plant. Bench tests were performed on this sample to find
optimum pH ranges for an alum - polyelectrolyte concentration ratio of 50:3
on- raw sewage (the test of 12/9/75 tested the effect of pH on CSO with alum
to polyelectrolyte concentration ration of 60:1). The results of these tests
are compared and plotted in Section VIII.
The final bench tests of this study were performed on Deer Island sewage
collected on 3/8/76. Thirty gallons were collected for further testing of
the interactions and effects of alum, polyelectrolyte and pH. Combined
results are shown in Table A-8. Bacterial analysis of these tests showed
excellent fecal colifortn removal (99.4%).
Excellent bench test results were obtained using the high gradient
magnetic separation treatment process. In overall bench study tests, the
45
-------
average removals for suspended solids, apparent color, turbidity and
bacteria were 93, 85, 91 and 98% respectively. This performance exceeds
that of conventional primary and secondary treatment systems.
CSO samples with both low and high solids loading were successfully
treated. Suspended solids and turbidity were generally reduced to 10 mg/1
and 10 FTU respectively, in spite of very high initial solids loading.
Reductions to as little as 1.8 mg/1 and 3 FTU were achieved.
The apparent color removal observed in these bench tests was consider-
ably better than in conventional treatment processes. Most color in CSO is
due to the presence of humic acids and humic-like materials. These chemicals
are chelating agents which will complex with the iron added in the floc-
culation process. It is probable that this complexing process results in
the formation of colored paramagnetic materials which can be easily removed
by a high gradient magnetic separator.
Pilot Plant Runs
A 500 liter sample of raw sewage (the influent to primary treatment
sedimentation tanks at Deer Island Sewage Treatment Plant) was collected
on 1/29/76. After initial jar tests to determine optimum flocculant con-
centrations, a test program was run on the pilot plant. TableA-6 gives
the combined results of all tests done on this raw sewage. It can be seen
from these data that SALA high gradient magnetic separators are highly
effective in treating this raw sewage in a continuous operation.
Tests performed to measure cycle to cycle consistency showed that less
than 2% variation existed between stabilized four minute cycles. This is
well within expected sampling contamination and analytical limits of error.
A 500 liter sample of CSO was taken from Cottage Farm on 2/2/76 for use
in a pilot plant run. Magnetite seed concentration was varied from 50 to
800 mg/1 using 4-minute cycles. A summary of the data from the 100-800 mg/1
magnetite-concentration treatment is given in Table A-7. Breakthrough was
encountered at a magnetite concentration of 50 mg/1. It should be noted that
a relatively short residence time was necessary (3 minutes) and low poly-
electrolyte and alum concentrations were used (1 mg/1 and 50 mg/1 respectively
with this CSO sample), yet the removal efficiencies are high.
A snow melt of 3/17/76 caused activation of the Cottage Farm facility.
Five hundred liters of CSO were collected for continuous pilot plant testing.
Several discrete test sequences were run on this sample including polyelectro-
lyte and alum variation, matrix loading tests, surge simulation runs, mag-
netic field variation, and optimum parameter runs to obtain consistency and
probability data. Combined data for these tests are given in Table A-8 and
for the optimized run alone in Table A-9. Solids loading in this CSO was
very high and separation efficiency by seeded water treatment was excellent
resulting in very high percent removals for all contaminants measured.
Suspended solids, apparent color, turbidity, fecal and total coliform
bacteria, total BOD and COD analyses were performed on these runs.
46
-------
Excellent results have been achieved with the continuous pilot plant
on both CSO and raw sewage. The level of performance obtained equals or
exceeds that of bench or jar tests.
The high level of performance is attained with a flocculation train
residence and filtration time of approximately three minutes, a fraction of
the time required for flocculation and processing in conventional waste
treatment systems. Additionally, there is an indication that, although the
floes formed are very small in size compared with those generally used for
conventional settling or filtering, the floes themselves are much less
susceptible to physical disruption. There is also an indication that the
addition of magnetic filter aid such as magnetite can reduce chemical reaction
time to less than ninety seconds. This may be attributed, in part, to the
fact that stirring during chemical additions in conventional jar tests is
done at twenty (20) RPM while in Sala's bench test and pilot plant mixing
is carried out at ninety (90) RPM. Additionally, there is evidence that
without the addition of alum and a polyelectrolyte certain contaminants such
as bacteria and viruses have an affinity for magnetite and may bond with it,
increasing removal efficiency for these contaminants.
Pilot plant tests have indicated that highly reproducible results may
be obtained in high gradient magnetic filtration of CSO and raw sewage.
Cycle to cycle variations in performance have not exceeded two percent (2%)
indicating the system's stability.
Seed concentrations needed relative to feed loadings were found to be
much lower than previously reported, an exciting result in terms of seed
cost and simplicity of the system (possible elimination of a seed recycle
process). Of particular potential value is the ability of the high gradient
magnetic separator to substantially reduce apparent color, biological con-
taminants (including both bacteria and viral pathogens) and trace heavy
metals.
47
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SECTION VIII
RESULTS AND DISCUSSION
INTRODUCTION
Experiments carried out on the pilot plant and bench apparatus were
designed to test independently the following parameters and their inter-
actions: alum, polyelectrolyte and magnetite concentrations, pH, magnetic
field strength, flow velocity, residence time, and matrix loading. Evaluation
of results was based chiefly on the analyses done on feed and treated samples
for suspended solids, apparent color and turbidity. Fecal and total coliform
counts were also performed on many of the samples. Selected treated and
untreated samples were analyzed for COD, BOD and trace metals.
Since the character of the waste water used during this study was very
different for each storm or sewage sample collected, a wide range of "types"
of wastes was encountered. Raw sewage of course differs from CSO. But even
CSO as observed at Cottage Farm fluctuates tremendously in solids loading,
etc. The time of year, time of the day, the amount of recent rainfall, the
source of water (rain, snow, snow melt) and the duration of the storm, all
affect the composition of the CSO. Likewise, raw sewage effluent varies a
great deal.
It is of course advantageous to test a new process with the full range
of waste waters to be encountered in a functional situation. But this also
makes the comparison of results somewhat more difficult, since different ini-
tial feeds necessarily mean slightly different levels of separation efficiency
in the purified product. In the graphs that follow, percent removal has been
plotted against the parameters varied. Since each storm was different, opti-
mal removal achieved in each testing series is not strictly comparable. Also,
complete optimization of those parameters being held constant was not usually
attempted. Nevertheless, the relationships shown are meaningful for all CSO
and raw sewage treated by high gradient magnetic separation. The shapes of
the curves are essentially constant, but the curves themselves may displace
slightly depending on the degree of optimization and the type of water being
treated.
INTERACTING CHEMICAL PARAMETERS
Alum
Alum [(^2804)3] was used in all tests performed as the principal coagu-
lant. Its concentration is a very important parameter for good separation,
48
-------
as without good floes non-magnetic particles will not be removed by the mag-
net. The key to seeded high gradient magnetic separation is, above all, to
flocculate a high percentage of the solids in the presence of magnetite. Once
this is accomplished the floes can easily be strengthened if necessary by an
organic polyelectrolyte and removed by the high gradient magnetic separator.
Optimal alum coagulation is directly dependent upon a number of inter-
related factors including pH, solids loading and character, and relative
amounts and kinds of other flocculating agents used (polyelectrolyte in the
present case). Optimum alum coagulation occurs at a pH of between 5.5 and
6.5 while polyelectrolyte flocculates best at around pH 8. Thus for CSO and
raw sewage, where tests have shown that both a coagulant (e.g. alum) and a
floe-strengthening agent (e-g- polyelectrolyte) are necessary, a compromise
must be made between the two pH extremes. Since results show that this com-
promise is not detrimental to magnetic separator efficiency it may in fact
prove to be advantageous, since the pH of CSO and sewage is usually close to
7 and amenable to this combination of chemical flocculants. It is thought
that pH adjustment should be minimal or eliminated altogether when these floc-
culants are used in the proper proportions. Except for certain tests devised
specifically to determine pH effects, all tests in this study were made at
natural pH. The excellent results obtained show that alum-polyelectrolyte
flocculation works well at normally encountered waste water pH values.
When polyelectrolyte concentration and pH are held constant, variations
in alum concentration show that optimum flocculation (and consequently
separation efficiency) is essentially dependent upon feed character. Gen-
erally, more heavily loaded influents require slightly higher alum concen-
trations than do less polluted waters. For each bench and pilot plant test
performed, jar tests were made to determine the optimum alum concentrations
necessary for good flocculation. The range encountered was rather narrow,
always falling between 50 and 120 mg/1 of aluminum sulfate, although as
little as 10 mg/1 difference for a particular waste water sample could make a
substantial difference in flocculation effectiveness.
Figure VIII-1 shows alum concentration versus percent removal of suspended
solids, apparent color and turbidity for the CSO collected on 3/17/76 and run
on the continuous pilot plant. Operating conditions used are indicated on
this and all subsequent figures. In this instance an alum concentration of
between 90 and 120 mg/1 was optimal. At the lower range of alum concen-
trations separation fell off rapidly, while the decrease in efficiency
decreased more gradually for concentrations above optimum. Tests conducted
without alum (and with polyelectrolyte) showed essentially no separation as
floes were very stringy and did not entrap significant amounts of the solids
in the water.
Polyelectrolyte
Polyelectrolyte concentration (Betz #1150) versus percent removal is
plotted in Figure VIII-2. This graph is also derived from data obtained in
the treatment of the CSO of 3/17/76. It can be seen from this figure that
separation efficiency seems to reach an optimal plateau above a certain
49
-------
FIGURE VIII-1
Ul
o
100
95
90
LU
QC
85
80
75
KEY
0 Suspended Solids
X Turbidity
O Apparent Color
Operating Conditions: Pilot Plant, CSO of 3/17/76
Magnetic Field Strength: 1.6 kG
Flow Velocity: 224 m/hr
Magnetite cone: 500 mg/£
Polyelectrolyte cone: 2.5 mg/£
Residence Time: 3 minutes
pH: Natural 7.3
- samples collected at 3-3.5 min in cycle
50 100 150
ALUM CONCENTRATION mg/l
200
-------
FIGURE VIII-2
95
90
85
UJ
oc
80
75
70
Q Suspended Solids
X Turbidity
O Apparent Color
Operating Conditions: Pilot Plant, CSO of 3/17/76
Magnetic Field Strength: 1. 6 kG
Flow Velocity: 224 m/hr
Magnetite Cone: 200 mg/£
Alum Cone: 100 mg/£
Residence Mixing Time: 3 min
pH: Natural 7.3
- samples taken at 3-3.5 min in 4 min cycles
0 .1
.5 1.0 2.0
POLYELECTROLYTE CONCENTRATION
2.5mg/l
-------
minimum concentration of polyelectrolyte (in this case, about 0.5 mg/1) . Be-
low this value separation drops off rapidly. This is explained by hydrody-
namic shearing forces, which break up the floes inside the matrix when too
little polyelectrolyte has been added. Earlier bench tests showed that when
flow velocity was decreased to 56 m/hr, the curve for polyelectrolyte was
essentially a straight line (i.e., polyelectrolyte was not needed at this
flow rate as the shearing forces were below the threshold of floe disruption) .
Likewise higher concentrations of polyelectrolyte may be necessary at flow
rates above the 224 m/hr used for Figure VIII-2.
As described above, pH plays an important role in the separation
achieved using alum and polyelectrolyte as flocculants. Figure VTII-3 shows
curves of pH versus suspended solids for two different types of waste (CSO
of 12/9/75 and raw sewage of 3/2/76) tested with two different alum to poly-
electrolyte concentration ratios (60:1 and 50:3 respectively). Other test
conditions were approximately equivalent. As is expected, when there is
relatively more polyelectrolyte present, optimal pH for separation efficiency
moves in the basic direction (towards pH 8) while when relatively more alum
is present, optimal pH moves in the opposite direction (towards pH 6). Other
chemical factors present in the waste may also play a part, but the flocculant
concentration ratios seemed to be of primary importance in the tests conducted
in this study.
While good flocculation was always achievable without pH adjustment,
somewhat better separation might have resulted in many instances by slight
pH adjustments. However, the acceptable range of pH for good separation is
wide enough to accommodate normal waste water fluctuations making continuous
pH monitoring and adjustment unnecessary.
MAGNETIC PARAMETERS AND THEIR INTERACTIONS
Magnetite Seed
Magnetite seed is necessary to impart a magnetic property to the floc-
culated solids in the water, thus allowing for floe retention inside the
magnetized matrix of SALA-HGMS magnetic separators. Figure VIII-4 shows
the relationship between magnetite concentration and percent removal of sus-
pended solids, apparent color, and turbidity on a pilot plant run (CSO of
2/2/76). The curve shows that a minimum concentration of magnetite (100 mg/1
in this case) is needed for optimal removal. Above this value additional
magnetite neither improves nor degrades separation efficiency. For concen-
trations below 100 mg/1 removal percentages decrease rapidly, indicating that
insufficient magnetite seed is available as nuclei around which floes may form,
The ratio of magnetite seed to suspended solids is critical for effective
separation, since unnucleated floes will not be trapped in the magnetic fil-
ter. The seed to solids ratio for tests in which effective separation took
place ranged from 0.38 to 3.05. The insensitivity of the system to magnetite
concentration above a certain level is advantageous since the concentration
52
-------
FIGURE VIII-3
On
OJ
16-1
=• 14
E
c/)
0
Q
UJ
Q
12
O 10
8
LU
(/) 6
KEY
CSO of 12/9/75
60 mg/£ alum
1 mg/£ polyelectrolyte
Raw Sewage of 3/2/76
50 mg/£ alum
3 mg/£ polyelectrolyte
Test Conditions: Bench Tests '_; :.
Magnetic Field Strength: 1.4; 1.9 kG
Flow Velocity: 224; 224 m/hr
Magnetite Cone: 1000; 8000 mg/£
Alum Cone: 60; 50 mg/£
Polyelectrolyte Cone: 1;3 mg/£
Residence Mixing Time: 3; 3 min
Sample Size: 1.6; 4 liters
5.5
6.0
6.5 7.0 7.5
PH
8.0
8.5
9.0
-------
100
FIGURE VI11-4
95
90
>
O
5
LJJ
85
80
KEY
CD Suspended Solids
X Turbidity
0 Apparent Color
Operating Conditions: Pilot Plant, CSO of 2/2/76
Magnetic Field Strength: 1.0 kG
Flow Velocity: 224 m/hr
Magnetite Cone: 50-800 mg/I
Alum Cone: 50 mg/£
Polyelectrolyte Cone: 1.0 mg/£
Residence Time: 3.0 min
pH: Natural 7.0
- sampled after 3 min of filtering in 4 min cycles
75
100 200 300 400 500 600
MAGNETITE SEED CONCENTRATION
700
800
mg/l
-------
FIGURE VIII-5
100!
95-
^90
O
LLJ
85-
80-
75
Suspended Solids
Turbidity
Apparent Color
Operating Conditions: Pilot Plant, CSO of 7/13/76
Magnetic Field Strength: 0;0.] ;0.5 ;1.0;1.6 ;1.9 kG
Flow Velocity: 224 m/hr
Magnetite Cone: 500 mg/£
Alum Cone: 100 mg/£
Polyelectrolyte Cone: 2.5 mg/£
Residence Time: 3 min
pH: Natural 7.3
- samples taken between 2 and 4 min in 4 min cycles
0 .1
1.0
1.5
2.
MAGNETIC FIELD (kG)
-------
used could either be set to vary automatically with the influent solids or
could be set at a single concentration just high enough to handle the highest
solids loading expected to be encountered.
Magnetic Field Strength
Like magnetite concentration, magnetic field strength has a rather
straightforward relationship to separation efficiency (Figure VIII-5). For
the high matrix loadings of the CSO of 3/17/76, a field of at least 0.5 kG
was necessary to hold the seeded floes. Almost total breakthrough occurred
at 0.1 kG, indicating the all-or-none type response typically obtained with
magnetic seeding techniques.
During surge flows, increased flow velocities through the SALA-HGMS
magnetic separator are necessary to accommodate the large volumes of water.
Increased flow rate means larger shearing forces will be present within the
system, especially within the matrix where drag forces are maximal. To over-
come this added stress the magnetic field must be increased to hold the mag-
netic floes more securely. In such cases, polyelectrolyte concentration may
also have to be increased so that floe breakup will not occur. Seed to
solids ratios used also have to be considered in surge flows as a higher
proportion of magnetite may be required to hold the floes in the magnetic
matrix.
Flow Velocity and Residence Time
Flow velocity and residence time are also directly related to surge
flow. As mentioned above, flow velocity through the magnetic matrix will
increase with increasing influent surges (unless reserve systems are adequate
to handle the flow). Also, if the flocculation mixing tanks are of fixed
capacity, a large surge will result in a faster turnover of water and there-
fore a shorter mixing time.
In the present study it was found that a residence time of only three
minutes was adequate for complete flocculation. Longer mixing times had
no adverse effects on separation efficiency. Thus this parameter is
relatively insensitive to change and need not be controlled precisely.
Figure VIII-6 shows limited data from a pilot plant run on the CSO of
3/17/76 where flow velocities were set at 55 m/hr and 222 m/hr respectively.
As the floe chain size remained unaltered, the residence times changed ac-
cordingly. Bench test runs on other waste water samples performed at 340, 450
and 565 m/hr showed similar trends (i.e. a gradual decrease in efficiency of
separation with increased flow velocities).
Matrix Loading
An important parameter to consider when designing a system is matrix
loading (the weight of the sludge successfully held in the magnetic matrix in
a single cycle divided by the weight of the matrix material). The size of the
magnet and the related system depends directly on the matrix volume needed
to handle the expected flow at reasonable flow velocities and within adequate
56
-------
FIGURE VIII-6
100
95
I
LU
DC
90
85
KEY
Q Suspended Solids
X Turbidity
Q Apparent Color
Operating Conditions: Pilot Plant,
CSO of 3/17/76
Magnetic Field Strength: 0.5 kG
Flow Velocity: 55-224 m/hr
Magnetite Cone: 500 mg/£
Alum Cone: 100 mg/£
Polyelectrolyte Cone: 2.5 mg/£
Residence Time: 3 min
pH: Natural 7.3
- samples taken between 2 and 4 min
in 4 min cycle
80
55
19)
225
(3)
340
450
565
FLOW RATE m/hr (FLOG TRAIN RESIDENCE TIME mini
-------
Ul
00
95-
90
85
LU
*80
75
70
FIGURE VII1-7
Operating Conditions: Pilot Plant,
CSO of 3/17/76
Magnetic Field Strength: 1.6 kG
Flow Velocity: 224 m/hr
Magnetite Cone: 500 mg/£
Alum Cone: 100 mg/£
Polyelectrolyte Cone: 1 mg/£
Residence Time: 3 min
pH: Natural 7.3
- samples taken every four minutes in 20 min cycles
LU
M
(121
KEY
Q Suspended Solids
X Turbidity
Q Apparent Color
1161
1201
.065 .228 .442 .655 .869
MATRIX LOADING IN SINGLE CYCLE OF 20 MINUTES
(TIME IN CYCLE min.J
1.08 g/g
-------
cycle time. Thus that point in a prolonged cycle at which filtration effi-
ciency drops below acceptable levels should be determined before a system
is designed.
Figure VIII-7 shows data obtained from continuous pilot plant operation
on the CSO of 3/17/76. Two identical continuous twenty-minute cycles were
run (with a single flushing interval between) with samples being collected
periodically throughout. Once again, the high total solids loading of the
feed (including suspended solids, magnetite, alum and polyelectrolyte) should
be noted (980 mg/1) as well as the flow rate (4 liters/minute). These fig-
ures give a 3.9 g/min input into the magnetic matrix, which itself weighs
only about 72 grams. Matrix loading calibrations given on the axis of Figure
VIII-7 are corrected values, taking into account the total solids input less
the amount which has broken through at the specified time into the cycle.
It is apparent from Figure VIII-7 that rapid breakthrough began to occur
somewhere between 12 and 16 minutes into the cycle (at matrix loadings of be-
tween 0.65 and 0.87 g solids/g matrix). In a previous continuous pilot plant
run (1/29/76, raw sewage) a twelve minute cycle produced a matrix loading of
0.38 g solids/g matrix without any measurable breakthrough. Once again, the
relative amount of polyelectrolyte used could make a difference in possible
matrix loading, since its chief value is in strengthening the floes. The
1/29/76 sewage had much lower solids loadings (620 mg/1) to begin with,
making the necessary polyelectrolyte concentration used (1 mg/1) relatively
higher than that required in the 3/17/76 run.
OPTIMAL PARAMETER RUNS
Using data from previous runs as a basis, the optimal parameter settings
can be approximated. It is evident from the preceding discussions that almost
all of the parameters tested interact with each other and with the influent
feed in complex ways. Thus the term "optimum" as used here is an oversimpli-
fication. As more is learned about the relative importance of all inter-
actions occurring in such a system, better fine tuning of the process will
inevitably become possible. Nevertheless, the presently known parameter
interactions are adequate to produce excellent results approximating the true
optimum magnetic separation possible.
Figure VIII-8 shows results from an optimized pilot plant run of about
one hour of continuous cycling. The CSO of 3/17/76 was used. Data are given
in tabular form in Table VIII-1. Ten consecutive four minute cycles were
sampled and analyzed to test the consistency and efficiency of separation
under these conditions. The only variable that may have changed slightly
during this run was the feed input loading. This was because the CSO was
drawn from a fifty-gallon drum during this run, and as the level of the water
in the drum decreased, higher solids loadings may have been encountered, de-
spite frequent agitation.
These results show that very high removal rates of suspended solids,
apparent color and turbidity can be achieved by magnetic separation. Com-
parison of these data with other figures reported in this study show sub-
stantial increases in percent removal for this optimized run. That is attri-
59
-------
FIGURE VI1I-8
% REMOVAL
99-
^ <7
98n
97-
96
95-
94-
93-
92-
Q1-
______ — O- C
J*~"
r^ 3 Suspended Solids
X Turbidity
O Apparent Color
\ / Operating Conditions: Pilot Plant, CSO of 3/17/76
X Magnetic Field Strength: 1.6 kG
Flow Velocity: 56 m/hr
Magnetite Cone: 420 mg/£
Alum Cone: 100 mg/£
Polyelectrolyte Cone: 2.4 mg/£
_— — — -°
— "^°^-^ ^-^°
Q o // Residence Time: 12 min
"-^^^^ ^^ ° pH: Natural 7.3
^\^_^^^ - samples taken between 1 and 4 minutes
O
in 4 minute cycles
RC1 RC2 RC3 RC4 RC5 RC6 RC7 RC8 RC9 RC10
CONTINUOUS PILOT PLANT REPEATED CYCLES
-------
butable to two factors. The first and most obvious is that optimized condi-
tions naturally give better separation than combined average data derived over
a wide range of non-optimum parameter variations. Secondly, it has been found
throughout this study that when good separation is being achieved (conditions
near optimum) solids in the filtrate (all forms) consistently reach the same
general minimum range of concentrations (1-10 mg/1), regardless of the solids
loading of the feed. Although it is true that highly polluted feeds cannot
have contaminant concentrations reduced to as low levels as lightly polluted
feeds, the difference is so small relative to the feed concentrations that
they are insignificant. The result of all this is that with heavily laden
feeds (like that of 3/17/76), higher percent removals will be obtained than
for less polluted waste waters. The same relationship holds true for fecal
and total coliform, and all other parameters of water quality tested in this
study.
Figure VIII-8 shows that variation in removal efficiency was small, about
1.2% for suspended solids, 1.5% for turbidity, and about 1.8% for apparent
color. During this continuous cycling, a slight increase in separation
efficiency is noted. This may be due to the changing quality of influent
feed or to a gradual stabilization of the system (note the slight drop in
percent removal early in the cycle).
Figure VIII-9 shows data from fecal and total coliform analyses on the
above optimized run. Feed concentrations are indicated by vertical bars,
indicating the variation encountered in the analysis of a single feed sampled
during this run. It is of interest to note that while percent removal of
suspended solids, apparent color and turbidity are increasing (concentrations
are decreasing) with running time (Figure VIII-8), the bacterial concentra-
tions in the filtered samples show a tendency to increase. This discrepancy
is difficult to explain. One possibility is that as the system stabilized, a
better overall separation was accomplished. At the same time, a stratifica-
tion of coliform bacterial concentrations in the feed barrel may have caused
a biasing of the input coliform concentration with time. In any case, the
difference from start to finish is only 0.2 to 0.3% in terms of percent of
the total bacteria removed.
Data from this optimized run were also used to plot cumulative proba-
bility curves for fecal and total coliform bacteria (Figure B-l) and suspended
solids and apparent color (Figure B-2). Because of the limited number of data
points the curves provide only approximations. The probability axis (X) gives
the percentage of the cycles tested in which values of the parameters plotted
(on the Y axis) are expected to be less than the value of Y. Due to the small
number of data points used, extrapolation to the outer limits is difficult
(especially in Figure B-l for coliform where substantial measurement varia-
tions are inherent with the technique itself).
Table A-ll shows results obtained from CSO analyses for the opti-
mized run of 3/17/76 as well as for the two previous continuous pilot plant
runs. High gradient magnetic separation consistently reduced COD an average
of 75% in these tests, regardless of the initial chemical oxygen demand
present in the CSO or raw sewage.
61
-------
Table A-12 shows raw data for trace metal analyses for the same three
pilot plant runs. It can be seen that magnetic separation was successful in
most cases in reducing trace metals to nondetectable or very low levels. On
the optimized run of 3/17/76 (labelled RC), a similar improving separation
can be seen for both COD and trace metals (confirming the trend noted above
for suspended solids, apparent color and turbidity, which is assumed to relate
to a gradual stabilization of the flocculation chain operation).
62
-------
TREATED
OJ
o
LU
-J
O
10 4
FEED
Fecal
Coliform
/C
105
FECAL COLIFORM
o TOTAL COLIFORM
Operating Conditions: Pilot Plant, CSO of
3/17/76
Magnetic Field Strength: 1.6 kG
Flow Velocity: 56 m/hr
Magnetite Cone: 420 mg/£
Alum Cone: 100 mg/£
Polyelectrolyte Cone: 2.4 mg/£
Residence Time: 12 min
pH: Natural 7.3
- samples taken between 1 and 4 min in 4
min cycles
106
~107
COLIFORM BACTERIA (cells/100ml)
Total
Coliform
<
M
H
108
FIGURE VIII-9 COLIFORM BACTERIA IN CONTINUOUS PILOT PLANT RUN
-------
SECTION IX
COMPARISON OF HIGH GRADIENT MAGNETIC
SEPARATION TO CONVENTIONAL TREATMENT
The comparison of high gradient magnetic separation to conventional pro-
cesses has been divided into separate comparisons for CSO and for sewage
treatment systems. This has been done because most conventional systems do
not perform as well in treating CSO as they do in treating dry weather flows.
The wide range in flows and influent characters causes the inadequacy in
conventional treatment of CSO.
COST COMPARISONS
For the CSO application high gradient magnetic separation compares favor-
ably with some tertiary level physical-chemical treatments. Table IX-1 below
compares costs of high gradient magnetic separation with various alternate
processes under evaluation for CSO treatment. The capital cost for a high
gradient magnetic separation integrated wet and dry weather flow facility is
$107,000/mgd as compared to $168,000/mgd for a comparable physical-chemical
facility, and $73,000/mgd for dual media filtration with polyelectrolyte.
Operation and maintenance costs are $0.137/1000 gal. for high gradient
magnetic separation, $0.187/1000 gal. for comparable physical-chemical treat-
ment and $0.169/1000 gal. for dual media filtration with polyelectrolyte.
Table IX-2 compares high gradient magnetic separation with several con-
ventional sewage treatment processes. High gradient magnetic separation also
compares very favorably for the treatment of raw sewage.
A cost comparison that is rather difficult to estimate, but that should
be mentioned, is that of reserve capacity. Systems employing high gradient
magnetic separators can increase capacity in two ways. One method is to
increase flow velocity while simultaneously increasing magnetic field and the
other is to bring additional magnetic separators into operation. Since
conventional systems generally do not have this flexibility, these two con-
siderations in particular make high gradient magnetic separation an attrac-
tive process.
Sludge handling considerations are another area where accurate compari-
sons cannot be made with the data presently available. Due to the presence of
the magnetite seed in the floes, the sludge generated is much denser (^20-
30% wt) than that produced in conventional waste water treatment. The mass of
the relatively heavy magnetite acts to reduce the sludge water content. Addi-
64
-------
TABLE IX - 1
COMPARISON OF CSO TREATMENT PROCESSES*
% REMOVAL
OPERATION AND
TOTAL COLIFORM CAPITAL COSTS**
TREATMENT PROCESS SUSPENDED SOLIDS BOD BACTERIA 25 MGD
High Gradient Magnetic 92-98 90-98 99-99.99 $ 2,672,600
Separation
Physical Chemical 99 94 99 4,190,000
Treatment***
Dual Media Filtration 36-92 66-79 — 1,817,000
with Polyelectrolyte
Rotating Biological 70 54 — 862,500
Contactor
Contact Stabilization 92 83 83 2,251,100
High Rate Trickling 65 65 83 2,275,600
Filtration
Dissolved Air Flotation 56-77 41-57 99 968,300
with Fine Screening
Microstrainers 70 50 — 325,500
MAINTENANCE**
$/1000 gal
$ 0.137
0.187
0.169
0.053
0.058
0.073
0.079
0.0023
* Reference #3
** Since operating costs from "Urban Stormwater Management and Technology: An Assessment" are
expressed in 1974, January $, these figures have been adjusted by +20% to effect a fair com-
parison to high gradient magnetic separation. Capital costs are adjusted to ENR = 2300.
*** Albany, N.Y. Pilot Plant (Ref. 3)
-------
TABLE IX - 2
COMPARISON BETWEEN HIGH GRADIENT MAGNETIC SEPARATION
AND OTHER SEWAGE TREATMENT PROCESSES*
TREATMENT PROCESS
% REMOVAL
SUSPENDED SOLIDS
COD
COLIFORM
BACTERIA
CAPITAL COSTS**
25 MGD
OPERATION AND
MAINTENANCE**
$71000 gal
High Gradient Magnetic
Separation
Chemical Clarification
Activated Sludge
Treatment
Physical Chemical
Treatment
88-95
60
55-95
99
60-75 99-99.9
70-80 90-98
80
99+
$ 2,672,600
1,522,500
11,132,000
4,190,000
$ 0.137
0.085
0.187
* Fair, G.M., Geyer, J.C. and Okun, D.A., Water Purification and Water Treatment and Disposal,
Vol. 2, John Wiley & Sons, New York, 1968, pp. 21-72.
** Since operating costs from "Urban Stormwater Management and Technology: An Assessment" are
expressed in 1974, January $, these figures have been adjusted by +20% to effect a fair com-
parison to high gradient magnetic separation. Capital costs are adjusted to ENR = 2300.
-------
tional cost savings may be realized from reduced thickener and dewatering
equipment size and better landfill properties.
COMPARISON OF REMOVAL PERFORMANCE
The removal performance of high gradient magnetic separation is
excellent in comparison with other processes. Tables IX-1 and IX-2
compare high gradient magnetic separation to some conventional treatment
systems.
The removal performance of high gradient magnetic separation exceeds
that of all but physical-chemical treatment. High gradient magnetic sepa-
ration, in a single stage treatment not only attains removal efficiencies
exceeding those of conventional treatment, but in addition, significantly
reduces the levels of phosphate'^--"), heavy metal (Table A-13) and viral
contamination'-^' in waste waters.
APPLICATION TO EFFLUENT POLISHING
High gradient magnetic separation can be utilized as a very good
effluent polishing step. Tests conducted on CSO indicate that suspended
solids levels of < 30 mg/1 can be successfully reduced to very low levels,
even < 2 mg/1. Heavy metal, viral, and phosphorus contamination can also
be reduced to low levels using this process. Capital and operation and
maintenance costs should also be considerably lower than conventional
systems for this application because pretreatment and sludge dewatering
systems would not be included in the high gradient magnetic separator
system.
67
-------
SECTION X
COST ESTIMATES FOR HIGH GRADIENT MAGNETIC SEPARATION TREATMENT
Estimated capital, operating and maintenance costs have been projected
from the data obtained in this study. The excellent removal efficiencies ob-
tained in the treatment of both CSO and raw sewage have indicated that high
gradient magnetic separation treatment would be best utilized for integrated
wet and dry weather flow systems. A schematic flow sheet for the 25 mgd
facility is shown in Figure X-l.
Table X-l below gives estimated capital costs for this system broken down
into subsystems. The cost estimate includes process control equipment for an
entirely automatic system. Costs for effluent quality analyzers are also
included.
TABLE X-l
25 MGD INTEGRATED WET AND DRY WEATHER FLOW TREATMENT FACILITY*
System Capital Cost
Pre-Screening $ 132,000
Floe Train and Chemical Feeding and Storage 293,900
Thickening and Dewatering Equipment 218,250
Backflush System 169,500
High Gradient Magnetic Separators (5 @ $165,600 ea.) 828,000
Pumps, Filter 47,300
Chlorination System 42,250
Process Control 108 000
Miscellaneous 30 000
Physical Plant 110,000
Installation Costs not Included in Above 229,600
$2,208,800
Construction Contingency 10% 220,800
$2,429,600
Engineering and Administration 10% 243,000
Total Capital Cost $2,672,600
*ENR = 2300
68
-------
FIGURE X-l
MAGNETITE
CONTROL
GATE
POLYMER PREP
SYSTEM
SLUDGE TO LANDFILL
OR INCINERATOR
84 in DIA.
SEPARATORS
-*- TO
RECEIVING
WATERS
HYDROTANK
CHLORINATION
SYSTEM
25 MGD SALA-HGMS INTEGRATED WET AND DRY
WEATHER COMBINED SEWER TREATMENT FACILITY
-------
Capital Costs Include: control gate, coarse bar screen, grit chambers,
rotary wedge wire screens, flash mixers, flocculators, flocculant feed
systems, chemical storage facilities, high gradient magnetic separator
systems, backflush systems, pumps, piping, conveyors, pH control,
chlorination system, physical plant, land, instrumentation, and pro-
grammable process control system.
Table X-2 following lists design parameter values used in obtaining estimated
costs.
TABLE X-2
Magnetic field strength
Flow velocity in matrix
Maximum flow capacity @
100 gpm/ft^ flow velocity
Nominal capacity
Back flush flow rate
Flow rate/magnetic separator @
maximum capacity, 100 gpm/ft^
flow velocity, and 90% duty cycle
Average influent suspended solids
Magnetite concentration
Alum concentration
Polyelectrolyte concentration
Pumping head for filter pumps
"G" factor for flash mixer
"G" factor for flocculators
Design Values
1.5 kG
245 m/hr (100 gpm/ft2)
1.18 m3/sec (25 mgd)
0.60 m /sec (12.5 mgd)
0.95 m3/sec
12.7 m3/min (3.4 x 103 gal/min)
300 mg/1
300 mg/1
100 mg/1
1.0 mg/1
7.6 m (25 ft)
300/sec
100/sec
Costs of a pH adjustment system are included although there is little indica-
tion that it would be required. Also costs for a conventional chlorination
facility are included. It is assumed that the sludge generated would be
shipped to incineration, landfill, or disposal facilities at a larger plant.
Evaluation of sludge characteristics would indicate the best disposal means.
Installation costs were based on estimates from equipment suppliers and
estimates from Perry's Chemical Engineer's Handbook.
70
-------
OPERATION AND MAINTENANCE
Operation and maintenance costs are based on operating conditions as
listed in Table X-2. The maintenance costs are based on annual operation at
50% capacity. Chemical costs are not included for pH control as pH adjustment
was not necessary for any tests conducted in this study. Similarly, the oper-
ating costs for the final chlorination step were not included due to lack of
data on the chlorine demand of the effluent. Table X-3 below gives operation
and maintenance costs expected for a 25 mgd integrated wet and dry weather
flow treatment facility based on annual operation at 50% of maximum system
capacity.
The operator labor is given for 24 hr/day monitoring of the facility. In
addition an 8 hour shift is included for routine labor in the facility (i.e.,
lubrication, cleaning bar and screening equipment). The operator labor figure
may be too conservative as the plant is designed for automatic operation.
An evaluation of the sludge handling costs is difficult due to the many
considerations necessary. These conditions are economic, ecological and
legal (referring to laws pertaining to disposal methods) in nature.
For many applications, especially those involving low solids loading, the
magnetite seed costs are small compared to other processing costs and thus a
recycle step may not be economically justified. Ecological considerations
such as improved land filling qualities resulting -from a very dense sludge may
also favor the seed discard option. On the other hand, seed recycle might be
advantageous for some large scale, continuous flow (dry weather flow) treat-
ment facilities. The economies of scale therein might justify the additional
capital expenditures in order to minimize such operational costs. Determina-
tion of representative characteristics for sludges generated by seeded high
gradient magnetic separation treatment will indicate which option is most
applicable to the specific case.
The electrical cost breakdown (Table X-4) shows that the power consump-
tion by the electromagnetic coils in the SALA-HGMS magnetic separators is
relatively small in comparison to power requirements of the other process
equipment. For operation at 1.5 kG mangetic field the magnetic separators
consume only 16% of the total power required.
LAND REQUIREMENTS
Approximate land area required for the above described facility would be
0.35 acres (0.14 hectares). Thus magnetic separation has the additional
economic and ecological advantages of consuming only a relatively small
amount of land. This is of course much more relevant in highly populated
areas where land costs may add significantly to capital investment or in
areas where large amounts of land simply are not available.
71
-------
TABLE X - 3
OPERATION AND MAINTENANCE COSTS
Chemicals
Alum @ $0.132/kg
100 mg/1
Magnetite @ $0.022/kg
300 mg/1 (does not include
freight charges)
Polyelectrolyte @ $3.10/kg
Total Chemical Costs
$/1000 gal
0.050
0.025
0.012
0.087
$/yr
(at 12.5 mgd)
$ 228,000
114,000
55,000
$ 397,000
Operator Labor
32 Manhours/day @ $10/hr
0.026
119,000
Maintenance
Mechanical Equipment and physical
plant (3% of equipment costs)
Electrical, Instrumentation and
Piping (2% of equipment costs)
Total Labor and
Maintenance
0.012
0.002
0.040
55,000
9,000
$ 183,000
Electrical
@ $0.020/kWh
SALA-HGMS magnetic separators
@ 1.5 kG require 85 kWh; other
equipment 440 kWh
Total Operations and
Maintenance Costs
0.010
0.137
46,000
$ 626,000
72
-------
TABLE X - 4
POWER CONSUMPTION
SALA-HGMS Magnetic 85 kWh
Separators @ 1.5 kG
Flash Mixer Units (3) 135
Flocculators 52
Air Compressor @ 70% 35
duty cycle
Vacuum Station 48
Filter Pump 130
Miscellaneous Consumption 40
Total 525 kWh
SALA-HGMS magnetic separators use approximately 16% of
total power consumption
73
-------
REFERENCES
1. Bitton, G., Fox, J.L. and Strickland, H.G., "Removal of Algae from
Florida Lakes by Magnetic Filtration," Applied Microbiology. 30:905,
1976.
2. Bitton, G., and Mitchell, R., "Removal of E. coli Bacteriophage by
Magnetic Filtration," Water Research, 8^548, 1974.
3. Urban Storm Water Management and Technology: An Assessment, EPA
670/S-74-040, December 1974.
4. Microstraining and Disinfection of Combined Sewer Overflow-Phase III,
EPA 670/2-74-049, August 1974.
5. High Rate Filtration of Combined Sewer Overflows, EPA Project #11023
EYI, April 1972.
6. Oberteuffer, J.A., "High Gradient Magnetic Separation," IEEE
Transactions on Magnetics, Vol. MAG-9(3): 303-306, 1973.
7. Oberteuffer, J.A., "Magnetic Separation: A Review of Principles,
Devices and Applications," IEEE Transactions on Magnetics, Vol.
MAG-10(2): 223-238, 1974.
8. Kolm, H., Oberteuffer, J.A. and Kelland, D., "High Gradient Magnetic
Separation," Scientific American, 233(5): 46-54, 1975.
9. Oberteuffer, J.A., Wechsler, I., Marston, P.G. and McNallan, M.J.,
"High Gradient Magnetic Filtration of Steel Mill Process and Waste
Water," IEEE Transactions on Magnetics, Vol. MAG-11(5): 1591-1593,
1975.
10. Herman, J.G., Industrial Water Engineering, 1969.
11. Okudo, T., Sugano, I. and Tsuji, T., "Removal of Heavy Metals from
Wastewater by Ferrite Co-Precipitation," Filtration and Separation,
12(5):472-478, 1975.
12. Mitchell, R., Bitton, G. and Oberteuffer, J.A., "High Gradient Magnetic
Filtration of Magnetic and Non-Magnetic Contaminants from Water,"
Separation and Purification Methods, 4(2): 267-304, 1976.
74
-------
13. Oder, R.R. and Horst, B.I., "Wastewater Processing with High Gradient
Magnetic Separators (HGMS)." Presented at 2nd National Conference
on Complete WateReuse, Chicago, May 1975.
14. Mitchell, R., Bitton, G. and DeLatour, C., "Magnetic Separation:
A New Approach to Water and Waste Treatment," Proc. 7th International
Conference on Water Pollution Research, Paris, 1974.
15. Bitton, G., Mitchell, R., DeLatour, C. and Maxwell, E., "Phosphate
Removal by Magnetic Filtration," Water Research, 8:107, 1974.
75
-------
APPENDIX A
TABLES OF SUMMARIZED DATA
TABLE A-l. BENCH TEST*
CSO COLLECTED ON
12/9/75
CONTROL AVERAGE
(Untreated CSO)
(// of Tests)
Range (Initial to
final)
TREATED CSO
Average
(// of Tests)
Range
% REDUCTIONS
Average
Range
TEST CONDITIONS
SUSPENDED SOLIDS
(mg/1)
40. 1
(6)
31.3 - 62. 1
2.75
(44)
0.8 - 7.9
93%
83 - 97%
APPARENT COLOR
(PCU)
224
(6)
185-273
31.2
(46)
18 - 55
87%
78 - 92%
TURBIDITY COLIFORM
(FTU) TOTAL @ 37°C on EMB
AGAR (cells/100 ml)
76.5 4.8 x
((>) (2)
63 - 95 1.6 x
5.65 7.4 x
(46) (4)
2-12 1.4 x
93% 98%
86 - 97% 97 -
^Combined results of
io8
IO8 - 8.0 x IO8
io6
IO5 - 1.3 x IO7
99.97%
7 series of tests
Magnetic Field 0.5 - 1.9 kG
Flow Velocity 49.2 - 390 m/hr
Alum Cone. 20 - 200 mg/1
Polyelectrolyte Cone. 0.25 - 1.5 mg/1
Magnetite Cone. 50 - 500 mg/1
pH 4.5 - 7.5
Residence Time 1-10 min
Sample Size 1.6 liters
done over a period of 7 days.
-------
TABLE A-2. BENCH TEST
CSO COLLECTED ON
12/19/75
SUSPENDED SOLIDS
(mg/1)
APPARENT COLOR
(PCU)
TURBIDITY
(FTU)
CONTROL AVERAGE
(Untreated CSO)
TREATED CSO
Average
(# of Tests)
Range
% REDUCTIONS
209
16.7
(3)
7.8 - 23.9
405
62
(3)
52 - 68
145
13
(3)
10 - 17
Average
Range
92%
89 - 96%
85%
83 - 87%
91%
88 - 94%
TEST CONDITIONS
Magnetic Field
Flow Velocity
Alum Cone.
Polyelectrolyte Cone.
Magnetite Cone.
pH
Residence Time
Sample Size
Matrix Loading
1.9 kG
210 m/hr
50 mg/1
1 mg/1
250; 500; 1000 mg/1
Natural
3 min
10 liters
0.16 g/g matrix
Magnetite Concentration Varied
-------
TABLE A-3. BENCH TEST
RAW SEWAGE COLLECTED
ON 12/26/75
SUSPENDED SOLIDS
(mg/1)
APPARENT COLOR
(PCU)
TURBIDITY
(FTU)
CONTROL AVERAGE
(Untreated CSO)
TREATED CSO
42
480
48
Average
(// of Tests)
Range
% REDUCTIONS
TEST CONDITIONS
Magnetic Field
Flow Velocity
Alum Cone.
Polyelectrolyte Cone.
Magnetite Cone.
pH
Residence Time
Sample Size
9.3
(3)
4.0 - 12.6
1.9 kG
210 m/hr
150 mg/1
2.4 mg/1
500 - 750 mg/1
Natural 7.2
^3 rain
10 liters
48
(2)
27 - 68
12
(2)
5-18
Average
Range
78%
70 -
90%
90%
86 -
94%
75%
63 -
90%
Magnetite Concentration Varied
-------
TABLE A-4. BENCH STUDY
CSO COLLECTED
12/31/75
CONTROL AVERAGE
(Untreated CSO)
TREATED CSO
Average
(# of Tests)
Range
% REDUCTIONS
Average
Range
TEST CONDITIONS
Magnetic Field:
Flow Flux Rate
Alum Cone . :
SUSPENDED
SOLIDS
(mg/1)
540
8
(10)
2.0 - 34
98%
94 - 99%
1.0 kG
210 - 530 m/hr
100 mg/1
APPARENT
COLOR
(PCU)
960
30
(6)
17 - 43
97%
96 - 98%
PH:
Residence Time
Sample Size:
TURBIDITY FECAL
(FTU) COLIFORM
(cells/100 ml)
430 2 x 108
6 7 x 105
(6) (1)
3-10
99% 99.7%
98 - 99%
natural 7.0
: 3 min
10 liters
Polyelectrolyte Cone.: 1.0 mg/1
Matrix Loading: 0.1 - 0.2 g/g matrix
Flow Velocity, Magnetite Cone., and Matrix Loading varied
-------
TABLE A-5. BENCH STUDY
CSO COLLECTED ON
1/28/76
SUSPENDED
SOLIDS
(mg/1)
APPARENT
COLOR
(PCU)
TURBIDITY
(FTU)
CONTROL AVERAGE
(Untreated CSO)
TREATED CSO
90
220
70
CO
o
Average
(# of Tests)
Range
% REDUCTIONS
Average
Range
10
(9)
6-15
89%
83 - 94%
79
(9)
62 - 100
64%
55 - 72%
14
(9)
- 18
80%
74 - 88%
TEST CONDITIONS
Magnetic Field:
Flow Velocity
Alum Cone.:
Polyelectrolyte Cone.
Matrix Length:
1 kG (permanent magnet)
210 m/hr
25; 50; 75 mg/1
1; 2; 3 mg/1
3 inches
Magnetite Cone.
pH:
Residence Time:
Sample Size:
250; 500; 1000 mg/1
natural
5 min
4 liters
Alum, Polyelectrolyte and Magnetite Cone, varied
-------
RAW SEWAGE COLLECTED
ON 1/29/76
TABLE A-6. CONTINUOUS PILOT PLANT
(2 Hour Run)
SUSPENDED APPARENT
SOLIDS COLOR
(mg/1) (PCU)
TURBIDITY
(FTU)
CONTROL AVERAGE
(Untreated)
TREATED
115
330
110
Average
(// of Tests)
Range
% REDUCTIONS
Average
Range
TEST CONDITIONS
Magnetic Field:
Flow Velocity
Alum Cone . :
Polyelectrolyte Cone.:
10
(21)
7.8 - 11.5
91%
90 - 93%
1.4 kG
210 m/hr
50 mg/1
1,2,3 mg/1
65
(21)
51 - 84
80%
74 - 84%
Magnetite Cone.:
PH:
Residence Time :
13
(21)
10 - 21
88%
81 - 91%
500 mg/1
natural 7 . 6
3 min
Polyelectrolyte Varied
-------
TABLE A-7. CONTINUOUS PILOT PLANT
(2% Hour Run)
CSO COLLECTED ON
2/2/76
CONTROL AVERAGE
Untreated CSO )
TREATED CSO
Average
(# of Tests)
Range
% REDUCTIONS
Average
Range
TEST CONDITIONS
Magnetic Field:
Flow Velocity
Alum Cone. :
Polyelectrolyte Cone. :
SUSPENDED
SOLIDS
(mg/1)
260
6
(10)
3.6 - 8.7
98%
97-99%
1.4 kG
210 m/hr
50 mg/1
1 mg/1
APPARENT
COLOR
(PCU)
400
38
(10)
26 -45
92%
89-93%
Magnetite
PH:
Residence
TURBIDITY
(FTU)
150
6
(10)
4-7
96%
95-97%
Cone.: 100; 200 ;
natural
Time : 3 min
FECAL
COLIFORM
(cells/100 mi;
2.0 x 106
1.0 x 105
(1)
95%
350;500;800 mg/1
7.0
Magnetite Cone. Varied
-------
TABLE A-8. BENCH TESTS
00
OJ
RAW SEWAGE COLLECTED
on 3/8/76
CONTROL AVERAGE
(Raw Sewage)
TREATED SEWAGE
Average
(# of Tests)
Range
% REDUCTIONS
Average
Range
TEST CONDITIONS
Magnetic Field:
Flow Velocity:
Alum Cone :
Polyelectrolyte Cone:
SUSPENDED
SOLIDS
(mg/D
147
8.4
(6)
4.9 - 15.6
94.3%
89 - 97%
1.95 kG
56 m/hr
100 mg/1
0; 1.8; 4; 5
APPARENT TURBIDITY FECAL
COLOR (FTU) COLIFORM
(PCU) (cells/100 ml)
130 - 140 105 1.4 x 107
53 8 8.9 x 104
(7) (7) (7)
41-71 6-12 5.6 - 18 x 10
83.6% 92.5% 99.4%
78 - 87% 89 - 94% 98.7 - 99.6%
Magnetite Cone: 500 mg/1
pH: 5.5; 6.0; 6.5;
8.0
Residence Time: 10 min
Sample Size:
4 liters
-------
TABLE A-9. CONTINUOUS PILOT PLANT
(6 HOUR RUN)
00
CSO COLLECTED ON
3/17/76
FEED AVERAGE
(// of Tests)
Range
TREATED CSO
Average
(// of Tests)
Range
% REDUCTIONS
Average
Range
TEST CONDITIONS
Magnetic Field:
Flow Velocity:
Alum Cone. :
Polyelectrolyte Cone. :
SUSPENDED APPARENT TURBIDITY
SOLIDS COLOR (FTU)
(mg/1)
460
(3)
400 - 520
28
(42)
4.1 - 185
94%
60 - 99%
0.1; 0.5
56; 225
50; 70;
0; 0.1;
(PCU)
650 230
(3) (3)
600 - 800 200 - 250
85 19
(42) (42)
41 - 210 8 - 65
87% 92%
68 - 94% 72 - 97%
; 1.0; 1.9 kG
m/hr
100; 150; 200 mg/1
0.5; 1; 2; 2.5 mg/1
FECAL TOTAL BOD
COLIFORM COLIFORM , .
(cells/100 ml) (cells/100 ml) ^S'1'
3.6 x 107 6.3 x 10? >79
(4) ? (4) (2)
2 - 5 x 10 5.1 - 7 x 10 >75 - 83
5.3 x 104 1.1 x 105 6.0
(6) , (6) (4)
1.5 - 13 x 10 0.70 - 2.2 x 10 5.2 - 7.0
99.85% 99.83% >92%
99.64-99.96% 99.65-99.88% >91-93%
Magnetite Cone.: 200; 420; 500 mg/1
pH: Natural 7.3
Residence Time: 3; 12 minutes
-------
TABLE A-10. CONTINUOUS PILOT PLANT: OPTIMIZED RUN
CX3
t_n
CSO COLLECTED ON
3/17/76
FEED AVERAGE
(1 sample only)
(// of Tests)
Range
TREATED SAMPLES
(Continuous Run)
Average
(// of Tests)
Range
% REMOVAL
Average
Range
TEST CONDITIONS
Magnetic Field:
Flow Velocity:
Alum Cone. :
Polyelectrolyte Cone.
SUSPENDED
SOLIDS
(mg/1)
460
(3)
400 - 520
6.0
(9)
4.1 - 9.1
98.7%
98.0-99.1%
1.6 kG
56 m/hr
100 mg/1
: 2.4 mg/1
APPARENT TURBIDITY
COLOR (FTU)
(PCU)
650 230
(3) (3)
600 - 800 200 - 250
47 8
(10) (10)
41-53 8-11
92.8% 96.3%
91.8-93.7% 95.2-96.5%
FECAL
COLIFORM
(cells/100 ml)
3.6 x 107
(4)
2.0-5.0 x 10
5.3 x 104
(6)
1.5-13 x 10
99.85%
99.64-99.96%
Magnetite Cone
PH:
Residence Time
Cycle Length:
TOTAL
COLIFORM
(cells/100 ml)
6.3 x 107
(4)
5.1-7.0 x 10
1.1 x 105
(6)
0.70-2.2 x 10
99.83%
99.65-99.88%
. : 420 mg/1
7.3
: 10 min
4 min
BOD *
(mg/1)
>79
(2)
>75-83
6.0
(4)
5.2-7.0
>92%
>91-93%
Samples collected between 1 and 4 minutes into cycle/Continuous stabilized Cycling of 50 minutes,
*Feed 6005 shown is not accurate as inadequate dilution (1:9) was used. Value is only a minimum
BODc possible. The actual undertermined value is expected to be much higher. Likewise the %
removal figures are underestimates.
-------
00
RAW SEWAGE OF 1/29/76*
TABLE A-11.
UNFILTERED
COD ANALYSES
(mg/1)
FILTERED
Feed
Treated (B-3)
% Reduction
CSO OF 2/2/76*
Feed
Treated (MA3)
Treated (MBl)
Average % Reduction
CSO OF 3/17/76 **
Feed 1
Feed 2
Treated (RC-6)
Treated (RC-7)
Treated (RC-8)
Treated (RC-9)
Treated (RC-10)
Average % Reduction
76 30
25 26
67%
137 35
35 32
26 33
78%
425
395
138
101
105
93.9
92.7
74%
* Analyses done by Process Research, Inc., Cambridge, Massachusetts
** Analyses done by Arnold Green Testing Laboratories, Inc., Natick, Massachusetts
-------
OO
TABLE A-12. TRACE METAL ANALYSES (mg/1)
Cd Pb Cr Hg Zn
Cu
Ni
RAW SEWAGE OF 1/29/76*
Feed
Treated (B-l)
% Reduction
CSO OF 2/2/76*
Feed
Treated (MA- 2)
% Reduction
CSO OF 2/2/76**
Feed
Treated (MA-1)
% Reduction
CSO OF 3/17/76*
Feed
Treated
{Optimized
Runs}
{0.5 kG}
{1.0 kG}
[1.6 kG}
{1.9 kG}
(RC-3)
(RC-7)
(RC-9)
(RC-10)
(SS-2B)
(SS-2A)
(A3-B)
(SS-2C)
Average % Reductions
< 0.05
< 0.05
—
< 0.05
< 0.05
—
< 0.05
< 0.05
—
.05
< .02
< .02
< .02
< .02
< .02
< .02
< .02
< .02
> 60%
< 0.5
< 0.5
—
< 0.5
< 0.5
—
0.15
< 0.05
> 67%
.2
< .2
< .2
< .2
< .2
< .2
< .2
< .2
< .2
> 0%
< 0.1
< 0.1
—
< 0.1
< 0.1
—
0.02
< 0.01
> 50%
.2
< .1
< .1
< .1
< .1
< .1
< .1
.1
< .1
> 50%
0.0011
0.0005
55%
0.0006
0.0007
0%
—
—
—
.0060
.0016
Contain.
.0008
.0006
< -0005
.0012
Contain.
< .0005
> 86%
0.50
0.11
78%
0.24
0.11
54%
0.20
< 0.05
> 75%
.71
.08
.04
.04
.04
.10
.08
.10
(.43)
90%
0.20
0.10
50%
0.15
0.05
67%
—
—
—
.66
.35
.31
.27
.27
.35
.35
.35
.35
51%
0.3
0.1
67%
0.3
0.3
0%
—
—
.2
< .2
< .2
< .2
< .2
< .2
< .2
< .2
< .2
—
("< " indicates undetectable concentrations present)
* Analyses done by EPA Analytical Applications Laboratory and Cincinnati Water Research Laboratory,
Cincinnati, Ohio
**Analyses done by Process Research, Inc., Cambridge, MA
-------
TABLE A-13. COMPARISON OF ALL PILOT PLANT AND BENCH RESULTS
Co
CO
PILOT PLANT
% Removals
Average
(# of tests)
Range
BENCH TESTS
% Removal s
Average
(# of tests)
Range
SUSPENDED
SOLIDS
93.7
(73)
60-99
92.7
(75)
70-98
APPARENT
COLOR
85.7
(73)
68-94
84.7
(73)
55-98
TURBIDITY
91.4
(73)
72-97
91.3
(73)
63-99
FECAL
COLIFORM
99.85
(7)
99.64-99.96
99.4
(8)
98.7-99.7
TOTAL
COLIFORM
99.83
(6)
99.65-99.88
98
(4)
97.99.97
-------
00
TABLE A-14. SUMMARY OF PERCENT REMOVALS FOR ALL TESTS
(BENCH AND PILOT PLANT)
cso
AVERAGE OF ALL
SAMPLES TESTED
(% removals)
Range %
(#of Tests)
RAW SEWAGE
AVERAGE OF ALL
SAMPLES TESTED
(% removals
Range %
(// of Tests)
SUSPENDED
SOLIDS
95
83-99.1
(85)
91
70-93
(30)
APPARENT
COLOR
87
55-98
(78)
82
74-94
(30)
TURBIDITY
93
74-99
(77)
88
81-91
(30)
FECAL TOTAL BOD
COLIFORM COLIFORM
99.2 99.3 >92
95-99.96 97-99.89 >91-93
(8) (10) (4)
99.4
98.7-99.6
(7)
-------
APPENDIX B
CUMULATIVE PROBABILITY CHARTS
10 yw.99
9
80
99.999.8 99 98 95 90 80 70 60 50 40 30 20 10 5 2 1 0.5 0.2 0.1 0.05 0.01 10
0.01 0.05 0.1 0.2 0.5 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 99.8 99.9 99.99
-------
T Y 99.99 99-9 99.8 99 98 95 90 80 70 60 50 40 30 20 10 5 2 1 0.5 0.2 0.1 0.05
0.01
0.01 0.05 0.1 0.2 0.5 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 99.8 99.9 99.99 "
-------
APPENDIX C
RAW DATA
BENCH TEST TREATMENT CONDITIONS
SAMPLE
NO.
Feed 1
Al
A2
A3
A4
A5
A6
A7
Feed 2
Feed 3
Bl
B2
B3
B4
B5
B6
B7
B8
B9
Feed 4
Cl
C2
C3
C4
C5
C6
C7
DATE
TESTED
12/9/75
CSO Sam-
ple Size
of 1.6
liters
Bench
Tests
12/11/75
CSO Sam-
ple Size
of 1.6
liters
Bench
Test
12/12/75
CSO Sam-
ple Size
of 1.6
liters
Bench
Test
ALUM
(mg/D
_
60
60
60
60
60
60
60
_
-
63
63
63
63
63
63
63
63
63
_
20
50
75
100
150
200
100
MAGNETITE
(g/1)
_
1.0
1.0
1.0
1.0
1.0
1.0
1,0
_
-
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
_
1.0
1.0
1.0
1.0
1.0
1.0
1.0
POLYELECTRO-
LYTE (mg/1)
1.0
1.0
1.0
1.0
1.0
1,0
1,0
_
-
1.0
1,0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
_
1.0
1.0
1.0
1.0
1.0
1.0
1.0
FLOW RATE
(1/min)
2.2
2.2
2.2
2.2
2.2
2.2
2.2
_
-
120
20
40
60
80
100
60
160
205
_
2.36
2.36
2.36
2.36
2.36
2.36
2.36
RESIDENCE
TIME (win)
4
4
4
4
4
4
4
_
-
4
4
4
4
4
4
4
4
4
_
4
4
4
4
4
4
4
PH
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
MAGNETIC FIELD
( kG)
1.9
1.65
1.65
1.3
1.0
0.75
0.50
_
-
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
_
1.5
1.5
1.5
1.5
1.5
1.5
1.5
-------
BENCH TEST PERFORMANCE DATA
SAMPLE
NO.
Feed 1
Al
A2
A3
A4
A5
A6
A7
Feed 2
Feed 3
Bl
B2
B3
B4
B5
B6
B7
B8
B9
Feed 4
Cl
C2
T3
w ~J
C4
C5
rfi
\~> vJ
r.i
COLOR
(PCU)
185
19
?6
£- \J
27
28
30
28
32
190
< 195
22
27
31
21
18
21
27
29
£- J
25
260
55
30
31
~J J-
27
26
36
91
TURBIDITY
(FTU)
63
6
5
_j
6
5
6
5
_J
5
62
< 64
5
5
5
5
5
5
A
\J
2
5
86
li
6
5
4
5
7
4
SUSPENDED
SOLIDS
(mg/1)
25.7
1.5
"~~
2.4
3.5
0.8
0.8
32.3
< 30.3
2.2
1.8
1.6
0.9
1.6
3.4
1 5
J- • _J
1 3
J- • J
3.5
46.1
6. 5
3.4
3 2
^J t Z-
2. 8
5.6
7 . 9
3.1
SETTLEABLE TOTAL COLIFORM
SOLIDS BACTERIA ON EMB
AGAR AT 37°C
(cells/lOOml)
Small Fibers
0
0
0
0
n
0
Small Fibers 1.6 x 108
0
0
0
0
0
0
0 3.4 x 106
n
n
0
Some Fibers
n
0
n
n
5
0 1.4 x 10
n
n
-------
BENCH TEST TREATMENT CONDITIONS
SAMPLE
NO.
Feed 5
DO
Dl
D2
D3
D4
D5
D6
D7
Feed 6
El
E2
E3
E4
E5
E6
E7
E8
DATE
TESTED
12/12/75
CSO Sam-
ple Size
of 1.6
liters
Bench
Test
12/12/75
CSO Sam-
ple Size
of 1.6
liters
Bench
Test
ALUM
(mg/D
_
63
63
63
63
63
63
63
63
_
63
63
63
63
63
63
63
63
MAGNETITE
(g/D
_
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
_
50
100
250
500
1000
2500
5000
500
POLYELECTRO-
LYTE (mg/1)
0
.25
.50
.75
1.0
1.25
1.50
1.0
_
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
FLOW RATE
(1/min)
2.3
2.3
2.3
2.3
2.3
2.3
2.3
2.3
_
2.3
2.3
2.3
2.3
2.3
2.3
2.3
2.3
RESIDENCE
TIME (min)
4
4
4
4
4
4
4
4
_
4
4
4
4
4
4
4
4
PH
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
MAGNETIC FIELD
(kG)
_
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
_
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
-------
BENCH TEST PERFORMANCE DATA
v-D
Ln
SAMPLE
NO.
Feed 5
DO
Dl
D2
D3
D4
D5
D6
D7
Feed 6
El
E2
E3
E4
E5
E6
E7
E8
COLOR
(PCU)
270
35
38
37
40
39
38
37
37
295
27
27
30
33
36
46
55
35
TURBIDITY
(FTU)
88
5
5
5
5
6
5
6
5
95
12
5
4
5
5
9
10
7
SUSPENDED
SOLIDS
(mg/1)
39.6
2.6
3.0
2.4
2.9
3.3
3.5
2.2
4.0
47.6
1.7
2.5
2.6
2.1
3.2
3.5
5.2
3.6
SETTLEABLE
SOLIDS
Fibers
0
0
0
0
0
0
0
0
Fibers
0
0
0
0
0
0
0
0
TOTAL COLIFORM
BACTERIA ON EMB
AGAR AT 37°C
(cells/lOOml)
7
1.3 x 10
7
1.3 x 10
-------
BENCH TEST TREATMENT CONDITIONS
SAMPLE
NO.
Feed 7
HI
H2
H3
H4
H5
H6
H7
Feed 8
Feed 9
Gl
G2
G3
G4
G5
G6
G7
G8
Feed
Tl
T2
T3
Feed 1
Feed 2
LI
L2
L3
DATE
TESTED
12/12/75
CSO Sam-
ple Size
of 1.6
liters
Bench
Tests
12/12/75
CSO Sam-
ple Size
of 1.6
liters
Bench
Test
12/19/75
CSO Sam-
ple Size
of 10 1.
12/26/75
Raw Sew-
age Sam-
ple Size
of 10 1.
ALUM
(mg/1)
63
63
63
63
63
63
63
—
-
63
63
63
63
63
63
63
63
_
50
50
50
_
-
150
150
150
MAGNETITE
(g/D
_
1.0
1.0
1.0
1.0
1.0
1.0
1.0
_
-
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
_
1.0
0.50
0.25
_
-
.5
.75
.75
POLYELECTRO-
LYTE (mg/1)
1.0
1.0
1.0
1.0
1.0
1.0
1.0
_
-
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
_
1.0
1.0
1.0
_
-
2.4
2.4
2.4
FLOW RATE
(1/min)
2.3
2.3
2.3
2.3
2.3
2.3
2.3
_
-
2.3
2.3
2.3
2.3
2.3
2.3
2.3
2.3
_
4
4
4
_
-
4
4
4
RESIDENCE pH MAGNETIC FIELD
TIME (min) (kG)
1
2
3
4
6
10
3
_
-
4
4
4
4
4
4
4
4
_
3
3
3
_
-
3
3
3
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.3
7.3
4.5
5.5
6.0
6.5
7.2
7.0
7.5
6.5
7.0
7.0
7.0
7.0
7.2
7.2
7.2
7.2
7.2
_
1.5
1.5
1.5
1.5
1.5
1.5
1.5
_
-
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
_
1.9
1.9
1.9
_
-
1.9
1.9
1.9
-------
BENCH TEST PERFORMANCE DATA
SAMPLE
NO.
Feed 7
HI
uo
H3
H/i
HS
Hfi
H7
Fppd 8
Feed 9
Gl
G2
T3
G4
G5
06
G7
G8
Feed
XI
T2
T3
Feed 4
Feed 2
LI
L2
L3
COLOR
(PCU)
430
31
ID
26
33
OA
34
31
ss
<448
106
95
58
51
55
43
43
30
405
68
52
66
480
27
68
TURBIDITY
(FTU)
158
5
c
7
A
c
£
f.
48
<165
24
19
1 ?
8
8
9
8
5
145
17
10
13
48
5
18
_
SUSPENDED
SOLIDS
(mg/1)
62.1
2.0
1 7
2.2
1 Q
1 7
o n
9 7
77 £
<55.2
12 8
1 6 3
Q £
4 3
7 3
6 4
6.5
7 i
209
18 5
7 8
23 9
41.3
41.9
4.4
11.2
12.6
SETTLEABLE
SOLIDS
0
0
n
0
n
n
u
A
n
< Fibers
o
n
n
n
o
o
0
o
COLIFORM BACTERIA
FECAL /TOTAL
(cells/lOOml)
0
— /8 x 10
— / —
.
'.
.
/
.
.
'
',
.
1
.
'
'
:
'.
I
-------
BENCH TEST TREATMENT CONDITIONS
00
SAMPLE
NO.
Feed 1
Al
A2
A3
A4
A5
A6
A7
A8
Feed 2
Bl
B2
B3
Feed 3
Cl
C2
C3-1
C3-3
C3-2
C4
C5
Feed 4
Dl
D2
D3
DATE
TESTED
1/1/76
Raw Sew-
age Sam-
ple Size
of 10
liters
Bench
Tests
1/1/76
Raw Sew-
age Sam-
ple Size
of 10
liters
Bench
Test
1/2/76
Raw Sew-
age Sam-
ple Size
of 10
liters
Bench
Tests
ALUM MAGNETITE
(mg/1) (g/1)
100
100
100
100
100
100
100
100
_
100
100
100
-
100
100
100
100
100
100
100
_
100
100
100
0.5
1.0
0.4
0.4
0.5
0.5
0.75
0.75
_
0.5
0.5
0.5
-
0.5
0.4
0.3
0.3
0.3
0.2
0.1
_
0.5
0.5
0.5
POLYELECTRO- FLOW RATE
LYTE (mg/1) (1/min)
_
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
_
0.4
0.8
1.5
-
1.0
1.0
1.0
1.0
1.0
1.0
1.0
_
1.0
1.0
1.0
_
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
_
4.0
4.0
4.0
-
4.0
4.0
4.0
4.0
4.0
4.0
4.0
_
6.0
8.0
10.0
RESIDENCE pH MAGNETIC FIELD
TIME (min) (kG)
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
-
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
1.9
1.9
1.9
1.9
1.9
1.9
1.9
1.9
_
1.9
1.9
1.9
-
1.0
1.0
1.0
1.0
1.0
1.0
1.0
_
1.0
1.0
1.5
-------
BENCH TEST PERFORMANCE DATA
SAMPLE
NO.
TTpeirl 1
Al
A2
A T
A R
Aj
A A
A7
AH
TTppr! ?
"R1
R?
-RQ
Feed 3
n
r?
C3-1
C3-3
po o
pA
rs
Feed 4
T)1
f)9
m
COLOR
(PCU)
7^n
38
42
-
i onn
i 7
OQ
28
32
960
31
43
78
TURBIDITY
(FTU)
1 9 S
9
10
~
-
^AS ^70
•3
f,
6
4
430
6
10
6
SUSPENDED SETTLEABLE
SOLIDS SOLIDS
(mg/1) (ml/1)
m^l 9 R
3.2
4.5
i n "^
11.2
1 ? 6
70S
11 0
360
1 8
3 S
4.2
3.7
S 6
34 4
1 ? 7
538
3 5
7 0
S 8
COLIFORM BACTERIA
FECAL /TOTAL
(cells/lOOml)
/
/
.
.
',
/
' .
'.
.
/
'.
7 x 105/2 x 107
1
.
1.5 x 107/5 x 108
'.
/
-------
BENCH TEST TREATMENT CONDITIONS
o
o
SAMPLE
NO.
Feed
1
2
3
4
5
6
7
8
9
DATE
TESTED
1/28/76
CSO Sam-
ple Size
of 4
liters
Bench
Test
ALUM
(mg/l)
_
50
50
50
25
50
75
50
50
50
MAGNETITE
(£/!)
1.0
0.5
0.25
0.25
0.25
0.25
1.0
1.0
1.0
POLYELECTRO-
LYTE (mg/l)
_
3.0
3.0
3.0
1.0
1.0
1.0
1.0
2.0
3.0
FLOW RATE
(1/min)
_
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
RESIDENCE
TIME (min)
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
pH
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
MAGNETIC
(kG)
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
-------
BENCH TEST PERFORMANCE DATA
SAMPLE
NO.
Feed
1
2
3
4
5
6
7
8
9
COLOR
(PCU)
220
78
82
100
96
69
78
62
71
72
TURBIDITY
(FTU)
68
16
16
18
15
8
14
12
12
14
SUSPENDED
SOLIDS
(mg/1)
67
14.8
14.4
8.5
9.8
5.5
10.8
6.1
8.8
7.8
-------
PILOT PLANT TREATMENT CONDITIONS
SAMPLE DATE ALUM
NO. TESTED (mg/1)
Feed
Al
A2
A3
A4
Bl
B2
B3
B4
Cl
C2
C3
C4
Dl
D2
El
E2
Gl
G2
G3
G4
G5
G6
1/30/76
Raw Sew- 50
age 50
Pilot 50
Plant 50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
50
MAGNETITE
(g/D
0.5
.5
.5
.5
.5
.5
. 5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
TIME(min) MAGNETIC
POLYELECTRO- FLOW RATE RESIDENCE pH IN CYCLE FIELD
LYTE (mg/1) (1/min) TIME (min) .SAMPLE TAKEN (kG)
3
T
3
3
3
3
3
3
3
3
3
3
2
2
1
1
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
3
^
3
3
3
o
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
7.6
7.6
7.6
7.6
7.6
7.6
7.6
7. 6
7.6
7.6
7.6
7.6
7.6
7.6
7.6
7.6
7.6
7.6
7.6
7.6
7.6
7.6
7.6
0-.5
1-1.5
2-2.5
2.5-3
0--5
1-1.5
2-2.5
2.5-3
0-.5
1-1.5
2-2.5
2.5-3
1.5
1.5
1.5
1.5
2-2.5
4-4.5
6-6.6
8-8.5
10-10.5
11-11.5
-
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
-------
PILOT PLANT PERFORMANCE DATA
SAMPLE
NO.
Feed
Al
A2
A3
A4
Bl
B2
B3
B4
Cl
C2
C3
C4
Dl
D2
El
E2
Gl
G2
G3
G4
G5
G6
COLOR
(PCU)
325
53
59
60
63
51
60
57
58
61
61
70
79
63
69
69
84
83
62
62
71
61
TURBIDITY
(FTU)
112
10
12
11
13
10
11
11
11
10
13
14
17
13
12
12
21
20
11
12
16
18
SUSPENDED
SOLIDS
(mg/1)
114
10.1
11.0
9.8
9.0
8.0
9.2
7.8
8.3
10.7
8.8
10.8
11.5
9.4
10.1
11.0
11.1
10.8
9.7
9.6
10.1
8.0
-------
PILOT PLANT TREATMENT CONDITIONS
SAMPLE
NO.
Feed
MAI
MB1
MA2
MB2
MC2
MA3
MB 3
MA4
MB4
MAS
MBS
MA6
DATE
TESTED
2/3/76
CSO
Pilot
Plant
Cycle
Time
4 min.
ALUM MAGNETITE
(rng/1) (g/1)
50
50
50
50
50
50
50
50
50
50
50
50
.5
.5
.35
.35
.35
.2
.2
.1
.1
.05
.05
.8
TIME (min) MAGNETIC
POLYELECTRO- FLOW RATE RESIDENCE p!I IN CYCLE FIELD
LYTE (niR/1) (1/min) TIME (min) SAMPLE TAKEN fkG)
_
1
1
1
1
1
1
1
1
1
1
1
1
_
4
4
4
4
4
4
4
4
4
4
4
4
3
3
3
3
3
3
3
3
3
3
3
3
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
3-4
3-4
3-4
3-4
3-4
3-4
3-4
3-4
3-4
3-4
3-4
3-4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
1.4
Feed 2
50
7.0
-------
PILOT PLANT PERFORMANCE DATA
SAMPLE
NO.
Feed
MAI
MB1
MA2
rLbZ
JXLAj
MA /i
M~R A
MR ^
MA A
JMAD
Foorl 9
COLOR
(PCU)
255
26
27
29
30
2o
29
~~
OQ
125
98
37
18S-A1 S
TURBIDITY
(FTU)
88
4
5
7
7
ft
9 ^
on
c:
i sn
SUSPENDED
SOLIDS
(mg/1)
112
4.5
3.6
R A
A Q
7 Q
7 7
-------
BENCH TEST TREATMENT CONDITIONS
SAMPLE
HO.
Ala
Alb
Ale
A2A
A2B
A3A
A3B
A4A
A4B
ASA
A5B
Feed
Feed
XI
X2
X3
X4
X5
X6
X7
X8
Feed
DATE
TESTED
3/2/76
Raw Sew-
age Sam-
ple Size
4 liters
Bench
Test
3/8/76
Raw Sew-
age Sam-
ple .Size
4 liters
Bench
Test
ALUM
(ng/1)
50
50
50
50
50
50
50
50
50
50
50
_
-
0
mo
100
100
100
100
100
109
MAGNET
.2
.2
.2
.8
.8
.8
.8
.8
.8
.8
.8
_
_
.5
.5
.5
.5
.5
.5
.5
.5
_
POLYELECTRO-
LYTE (tng/1)
1
1
1
3
3
3
3
3
3
3
3
-
-
4
0
1.8
0
0
5
1.8
5
-
FLOW RATE
(I/rain)
4
4
4
4
4
4
4
4
4
4
4
-
-
1
1
1
1
1
1
1
1
-
RESIDENCE
TIME (ffitn)
3
3
3
3
3
3
3
3
3
3
3
_
-
10
10
10
10
10
10
10
10
-
TIME(min)
pH IN CYCLE
SAMPLE TAKEN
7.07
7.07
7.10
7.07 -
7.15
6.06
6.04
7.55
7.49
8.30
8.21
7.07
7.07
8.00
6.49
7.10
5.49
6.00
7.99 _
7.09
7.14
7.09
MAGNETIC
FIELD
r(kG)
1.9
1.9
1.9
1.9
1.9
1.9
1.9
1.9
1.9
1.9
1.9
—
_
1.95
1.95
1.95
1.95
1.95
1.95
1.95
1.95
-
-------
BENCH TEST PERFORMANCE DATA
SAMPLE
NO.
Ala
A1D
Ale
AzA
AZD
AJA
A TD
AJD
A4A
A^frS
A C A
AjA
A ^"R
AJJS
t eed
i eed
XI
X2
X3
X4
X5
X6
X7
X8
Feed
COLOR
<;PCU)
135
46
49
71
62
50
41
49
320
TURBIDITY
(FTU)
25
6
7
12
9
8
6
7
105
SUSPENDED
SOLIDS
(mg/1)
12. 3
. 0
203 . 7
, 9
-i /-\ /,
J.U. 4
12 . 6
11. 9
-7 Q
/ . 0
. O
nQ
. y
in Q
1U. 9
/ J . 3
Tin Q
-LIU. o
17.4
4.9
5.4
15.6
9.2
7.2
7.9
147
COLIFORM BACTERIA
FECAL
(100 cells/ml)
6.0 x 106
7.0 x 104
7.1 x 104
5.6 x 104
1.0 x 105
1.8 x 105
6.5 x 104
8.4 x 104
1.4 x 107
-------
PILOT PLANT TREATMENT CONDITIONS
o
CO
SAMPLE
NO.
P1A
P1A2
P1B
P2A
P2A2
P2B
P3A
P4A
P5A
A1A
A2A
ASA
A3B
A3C
A4A
ASA
ML1A
ML2A
ML3A
ML4A
ML5A
ML6A
ML1B
ML2B
ML3B
ML4B
ML5B
ML6B
DATE ALUM
TESTED (mg/1)
3/17/76 100
CSO, CYCLE 100
I I.ME 4 Min. 100
Pilot 100
Plant 100
100
100
100
100
200
150
100
100
100
70
50
CYCLE 100
TIME 100
20 min. 100
100
100
100
100
100
100
100
100
100
MAGNETITE
(g/D
.2
.2
.2
.2
.2
.2
.2
.2
.2
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
.5
POLYELECTRO- FLOW RATE RESIDENCE pH TIME (min) MAGNETIC
LYTE (mg/1) (1/min) TIME (min) IN CYCLE FIELD
SAMPLE TAKEN (kG)
2.5
2.5
2.0
1.0
1.0
1.0
.5
.1
0
2.5
2.5
2.5
2.5
2.5
2.5
2.5
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
3-3.5
1-1.5
4-4.5
8-8.5
12-12.5
16-16.5
20-20.5
1-1.5
4-4.5
8-8.5
12-12.5
16-16.5
20-20.5
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
-------
PILOT PLANT PERFORMANCE DATA
SAMPLE
NO.
P1A
P1A2
P1B
P2A
P2A2
P2B
P3A
P4A
PSA
A1A
A2A
A3A
A3B
A3C
A4A
A5A
ML1A
ML2A
ML3A
ML4A
ML5A
ML6A
ML1B
ML2B
ML3B
ML4B
ML5B
ML6B
COLOR
(PCU)
83
67
79
81
72
100
84
160
210
110
83
73
71
64
119
120
63
75
94
134
110
170
78
87
95
90
130
170
TURBIDITY
(FTU)
14
11
15
16
10
16
13
49
57
33
14
11
10
11
25
41
10
15
17
29
49
65
8
14
18
29
30
53
SUSPENDED
SOLIDS
(mg/1)
15.3
10.2
15.1
23.0
11.7
26.0
33.0
66.0
94.0
49.0
17.6
12.3
9.0
9.7
24.0
52.0
14.5
12.7
30.0
38.0
72.0
185.0
13.8
22
33
38
57
99
-------
PILOT PLANT TREATMENT CONDITIONS
SAMPLE DATE
No. TESTED
RC1 3/17/76
RC2 CSO
RC3 CYCLE TIME
RC4 4 min.
RC5
RC6
RC7
RC8
RC9
RC10
SSI
SS2A
SS2B
SS2C
Feedl
Feed 2
ALUM MAGNETITE POLYELECTRO-
(mg/1) (g/1) LYTE (mg/1)
100
100
100
100
100
100
100
100
100
100
100
100
100
100
-
-
.42
.42
.42
.42
.42
.42
.42
.42
.42
.42
.5
.5
.5
.5
-
-
2.4
2.4
2.4
2.4
2.4
2.4
2.4
2.4
2.4
2.4
2.5
2.5
2.5
2,5
-
-
FLOW RATE
(1/min)
1
1
1
1
1
1
1
1
1
1
1
4
4
4
-
-
RESIDENCE pH TIME (min) MAGNETIC
TIME (min) IN CYCLE FIELD
SAMPLE TAKEN (kG)
12
12
12
12
12
12
12
12
12
12
12
3
3
3
-
-
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
7.34
2.5-4.5
1-4.5
1-4
1-4
2-4
2.5-4
1-4
1-4
1-4
1-4
1-4
2-4
2-4
2-4
-
-
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
1.6
0.5
1.0
0.5
1.9
-
-
-------
PILOT PLANT PERFORMANCE DATA
SAMPLE
NO.
RC1
RC2
RC3
RC4
RC5
RC6
RC7
RC8
RC9
RC10
SSI
SS2A
SS2B
SS2C
Feed 1
Feed 2
COLOR
(PCU)
50
50
53
50
51
44
42
45
42
41
46
61
64
61
650
800
TURBIDITY
(FTU)
8
8
11
8
9
8
8
8
8
8
8
11
10
9
230
250
SUSPENDED
SOLIDS
(mg/D
8.
7.
7.
9.
5.
4.
10.
4.
4.
4.
4.
9.
13.
8.
460
520
1
4
0
1
5
4
6
5
3
1
5
8
0
5
COLIFORM BACTERIA COLIFORM BACTERIA BOD
FECAL TOTAL 5
(100 cells/ml)
2
4
4
1
6
1
2
4
.3
.6
.3
.7
.4
.3
.6
.6
x 104
x 104
x 104
x 104
x 104
x. 105
x 10y
x 10
7
8
7
1
1
2
1
5
6
.0 x 104
.1 x 104
.6 x 104
.1 x 10-
.2 x 105
.7 x 105
.3 x 105
.9 x 107
.6 x 107
5.
5.
5.
7.
75
83
2
7
9
0
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APPENDIX D
GLOSSARY
Backflush - A rapid reverse flow of water through the separator matrix with
the magnet deenergized following a filtering interval which serves to purge
accumulated magnetic floes from the matrix.
Bench Test - A test performed manually on an aliquot of sample. More
specifically, a waste water sample is treated with known concentrations of
flocculants and seed while agitating, and is then passed through a gravity
feed high gradient magnetic separator and later analyzed.
Canister - The cylindrical copper or stainless steel container holding the
magnetic matrix.
Combined Sewer Overflow or Combined Storm Overflow (CSO) - A flow from a
sewer receiving both surface run off and municipal sewage in excess of inter-
ceptor capacity that is discharged into a receiving water.
Continuous Pilot Plant - Small scale sewage treatment plant which is set to
cycle automatically and continuously for feasibility studies.
Dry Weather Flow - The flow of municipal sewage during a dry spell in a
sewer also able to receive runoff.
First Flush - The condition, often occurring in storm sewer discharges and
combined sewer overflows, in which a disproportionately high pollutional
load is carried in the first portion of the discharge or overflow.
Flocculation Chain (or train) - A series of interconnected mixing tanks in
which flocculants and magnetic seed are added to the water to be treated by
magnetic separation.
High Gradient Magnetic Separator - A solenoid electromagnet containing a
filamentary ferromagnetic matrix and encased in a highly efficient iron
return frame.
Jar Test - Standard sewage treatment test in which several aliquots of
waste water are taken and treated with various concentrations of flocculants,
etc., to determine optimal dosages necessary for effective treatment.
Magnetic Matrix - The ferromagnetic material (steel wool or expanded metal)
located in the canister of a high gradient magnetic separator.
112
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Matrix Loading - The ratio of the weight of solids successfully held in the
magnetic matrix to the weight of matrix fiber.
Pilot Plant Cycle - Series of automatically timed and executed continuous
cycles including: reset, magnet on delay, filter, magnet off delay, flush
and dump cycles.
Sludge - Semi-solid end product of magnetic separation process consisting
of waste solids, magnetic seed and flocculants.
Surge Flow - Rapid increase in incoming volume of waste water into a treat-
ment or detention facility.
Wet Weather Flow - A waste water containing both runoff and raw sewage re-
sulting from the combining of storm waters with normal dry weather flow.
113
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APPENDIX E
ABBREVIATIONS AND MAGNETIC UNITS
Abbreviation
BOD,
COD
CSO
EMB
FTU
PCU
PFU
Description
Five-day Biochemical Oxygen Demand
Chemical Oxygen Demand
Combined Storm Overflow
Eosin Methylene Blue Agar Medium
Formazin Turbidity Units (= Jackson Turbidity Units)
Platinum-Cobalt Unit for Color (1 Color Unit =
1 mg/1 Platinum as Chloroplatinate Ion)
Plaque Forming Unit (For Virus Analysis, One PFU
represents one Virus in Original Sample)
Magnetic Unit
g/g
kG
m/hr
Description
A term used in matrix loading discussions meaning number
of grams of solids held by the matrix (magnetically)
per gram of matrix fiber.
Unit of magnetic field strength (Kilogauss)
(1 kG = 6452 lines/square inch)
Flow velocity through a unit area of a magnetic matrix
(number of cubic meters of water passing through a square
meter of matrix surface area in one hour). (1 m/hr =
0.41 gallons/min ft , and for our 1.5 inch diameter
matrices this is equivalent to a flow flux rate of
0.018 liters/min).
114
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APPENDIX F
CONVERSION FACTORS
115
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CONVERSION FACTORS*
English to Metric
English unit
•ere
• ere - foot
cubic foot
cubic feet per minute
cubic inch
cubic yard
degree Fahrenheit
feet per second
foot (feet)
gallon(s)
ga 1 luns per day
ga 1 Ions per Jay per
square foot
gallons per a mute
gallons per Minute per
square foot
gallons per square foot
horsepower
inch (es )
inches per hour
«i 1 1 ion gal Ions
»i 1 1 ion gallons per
acre per day
• 1 1 1 ion gallons per day
• lie
parts per billion
parts per Billion
pound { s )
pounds per day per «cre
pounds per 1 ,000 cubic feet
pounds per million gallons
pounds per cubic foot
pounds per square foot
pounds per square inch
square foot
square inch
square Bile
square yard
standard cubic feet
per ainute
ton (short)
yard
Abbr.
• ere
•cr«-f t
cf
C£B
cfs
cu in.
cy
deg F
fp.
fps
ft
gal.
gcd
epd
gpd/5q ft
ep»
gp»/sq ft
gPSf
hp
in.
in . /hr
• il gal .
• gad
• gd
mi
ppb
pp«
Ib
lb/acre/diy
Ib/day/acre
lb/1 ,UOO cf
)b/.ll gal .
pcf
psf
psl
sq ft
sq ia.
sq ni
sq yd
scf.
ton
yd
Multiplier
0.40S
1.255.5
28.32
0.0283
28.32
16.39
0.0164
0.765
764 .6
O.SS5 CP-32)
0.00508
0.305
0.30S
3.785
9.353
3.785
4.381 i 10"5
1.698 I 10"3
0.283
0.0631
2.445
0.679
40.743
0.746
2.54
2.54
3.785
3,785.0
0.039
43.808
0.0438
1.609
0.001
1.0
0.454
453.6
0.112
1.121
16.077
0.120
16.02
4.882 I 10"4
0.0703
0.0929
6.452
2.590
0.836
1.699
907.2
0.907
0.914
^
Abbr.
h«
cu •
1
I/sec
cu cm
1
CU B
1
deg C
u/sec
n/sec
•
1
1/day/ha
1/capita/day
I/sec
cu B/hr/sq *
cu B/ain/ha
I/sec
cu/m/hr/sq B
1/sq B
kv
cm
cm/hr
Ml
CU B
cu B/htr/sq B
I/sec
km
mg/1
mg/1
kg
1
g/day/sq •
kg/day/ha
g/cu .
mg/1
kg/cu •
kg/sq cm
kg/sq en
sq .
sq CH
sq k>
sq «
cu »/hr
kg
metric too
•
Metric unit
hect»re
cubic Meter
liter
cub ic centiaeter
1 i ter
cubic neter
liter
me Ler (s)
1 1 t <; r ( s )
liters per day per hectare
liters per capita per day
cubic meters per hour
cubic arters per ainute
per hectare
cubic meters per hour
per square mt: ter
square me te r
ki lowat ts
cen t imeter
centimeters per hour
meyaliters (liters x 10 )
cubic meters
cubic meters per hour
liters per second
ki loraeler
mi 1 1 igrarai per 1 iter
k i i ogram
grams
grarasj per day per square
me ter
kilograms per day per
hec tare
ml 1 1 igraos per 1 i ter
kilograms per cubic meter
kilograms per square
cen t ime Ler
kilograms per squa re
cent imeter
q
square k Home ter
square me ter
cubic meters per hour
ki lograms
metric ton
meter
* Taken from "Urban Stormwater Management and Technology; An Assessment",
Metcalf & Eddy, Inc., EPA Contract No. 68-03-0179, December, 1974.
116
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TECHNICAL REPORT DATA
(I'lcase read Instructions on 111? rci'cn'c' before completing)
] REPORT NO
EPA-600/2-77-015
4. TITLE AND SUBTITLE
TREATMENT OF COMBINED SEWER OVERFLOWS BY HIGH
GRADIENT MAGNETIC SEPARATION
7. AUTHOFUS)
David M. Allen, Richard L. Sargent,
and John A. Oberteuffer
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Sala Magnetics Inc.
247 Third Street
Cambridge, Massachusetts 02142
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory—Gin.,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
3. RECIPIENT'S ACCESSI Of* NO.
5. REPORT DATE
March 1977 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
10 PROGRAM ELEMENT NO.
1BC611
1 1. CONTRACT/GXK&NXNO.
68-03-2218
13. TYPE OF REPORT AND PERIOD COVERED
Final 6/75 - 7/76
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Seeded water treatment by high gradient magnetic separation techniques was
carried out on combined storm overflows and raw sewage influents. Both bench-type
and continuous pilot plant tests were performed to evaluate the effectiveness of
the process in purifying waste waters. Critical parameters were varied to determine
optimal removal efficiencies, sensitivities and relative importances of these vari-
ables. Attempts were also made to compare the effectiveness and economic feasibility
of high gradient magnetic separation treatment with present methods of waste water
treatment. Finally, recommendations for the next phase of study have been presented.
The results of the present study show this process to be a highly effective
method of reducing most forms of pollutants present in CSO and raw sewage to low
levels of contamination. Capital cost estimates for high gradient magnetic separation
systems also compare favorably with traditional secondary plants. Several additional
benefits are realized such as extremely high processing rates, small land requirement,
and lower chlorine demand (ecological benefits).
June 1975 and was completed July 1976.
Jork on this project was begun in
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Magnetic Separators
Flocculators
Sewage Treatment
Combined Sewers
Water Treatment
Filtration
b. IDENTIFIERS/OPEN ENDED TERMS
Combined Storm Overflow
SALA-HGMS Magnetic Separator
Seeded Water Treatment
High Gradient Magnetic Field
Continuous Pilot Plant
c. COSATI Held/Croup
13B
13H
3. DISTRIBUTION STATEMENT
Release to Public
19 SECURITY CLASS (Tilt's Report)
UN CLASS! PI HI)
21 NO OF PAGES
127
20 SECURITY CLASS (This pa^e)
UNCLASSIFIED
22 PRICE
EPA Form 2220-1 (9-73)
117
U. S. GOVERNMENT PRINTING OFFICE: 1977-757-056/5<)97 Region No. 5-11
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