Chemical Aids Manual
For Wastewater
Treatment Facilities
by
Nancy E. Heim
Bruce E. Burns
Culp/Wesner/Culp
Clean Water Consultants
Santa Ana, California 92707
EPA Contract No. 68-01-5085
EPA Project Officer
Lehn Potter
December 1979
U.S. Environmental Protection Agency
Office of Water Program Operations
Municipal Construction Division
Washington, DC 20460
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DISCLAIMER
This report has been reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect;
the views and policies of the U.S. Environmental Protection
Agency, nor does mention of trade names or commercial products
constitutes endorsement or recommendation for use.
To order this publication, MO-25, "Chemical Aids Manual
for Wastewater Treatment Facilities," write to:
General Services Administration (8BRC)
Centralized Mailing Lists Services
Building 41, Denver Federal Center
Denver, Colorado 80225
Please indicate the MCD number and title of publication.
Multiple copies maybe purchased from:
National Technical Information Service
Springfield, Virginia 22151
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ACKNOWLEDGEMENTS
This manual was prepared under the direction of Mr. Lehn J. Potter,
Project Officer, Watfer Program Operations of the U.S. Environmental
Protection Agency. Preparation and development of the manual was carried
out by Nancy E. Heim,-Bruce E. Burris, George M. Wesner, William E. Ettlich,
and William R. Whittenberg of Gulp/Wesner/Gulp.
Recognition also is due to the following individuals and their
staff for time and assistance in reviewing the draft manual:
Mr. Dom Calicura
Mr. Ken Meyer
Mr. Bernard Miller
Mr. David Deaner
Mr. Stan Martinson
City of Placerville, CA
El Dorado Irrigation District
Irvine Ranch Water District
California State Water Resources Board
California State Water Resources Board
The authors also-wish to thank the following individuals for their
contributions in making this manual possible:
Mrs. Joan Morrow
Mrs. Barbara Van Hoven
Ms. Amy Amirani
Typing
Editing
Drafting
iii
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TABLE OF CONTENTS
Disclaimer
Acknowledgements
List of Tables
List of Figures
1. INTRODUCTION 1
Purpose of Manual 1
Manual Organization .• . . . 2
Use of the Manual 3
2. PLANNING AND EVALUATING PLANT EFFECTS 8
Treatment Efficiencies . 8
Selecting Points for Chemical Addition 17
Guidance on Chemical Dosages 24
Sludge Considerations 34
References 45
3. SELECTING CHEMICALS FOR USE 46
Effectiveness 47
Cost 48
Reliability of Supply 49
Sludge Considerations 51
Compatibility with Other Treatment Processes 52
Environmental Effects 52
Labor Requirements 52
References 56
4. FEEDING & HANDLING SYSTEMS 57
Dry Chemical Feeders 58
Solution Feeders • • 67
Gas Feeders 70
Feed System Requirements for Specific Chemicals ... 70
Storage ; 87
Piping and Handling Materials . 93
Manual and Flow Pacing Control for Chemical Feed
Systems 93
Automatic Control for Chemical Feed Systems 100
References . . . . 102
IV
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5. PROBLEMS WHICH CAN BE AIDED BY CHEMICAL ADDITION
Collection Systems . .....
Conventional Wastewater Treatment .....
Advanced Waste Treatment . . . .
Sludge Treatment and Conditioning . . . . .
APPENDIX—INFORMATION ON CHEMICALS
Appendix Index ........
103
105
108
126
132
A-l
A-2
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TABLES
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Distribution of HOC1 and OC1~ with pH , 9
Effect of Chemical Treatment on Primary Clarifier
Performance H
Polymer Addition to Primary Clarifier 13
Lime Addition to Primary Clarifier 14
Effect of Chemical Treatment on Clarifier Performance .. 15
Typical Solid Bowl Centrifuge Performance ....... 18
Typical Design and Performance Data for Vacuum Filters 19
Typical Performance Data for Pressure Filters 20
Techniques for Evaluation of Chemical Dosages 25
Chlorine Dosage Ranges 26
Neutralization Factors for Common Alkaline and Acid
Reagents « 32
Typical Chemical Dosages for Sludge Conditioning ... 33
Chemical Dosage Guide . 35
Additional Sludges to be Handled with Chemical
Treatment Systems: Primary Treatment for Removal of
Phosphorus 36
Additional Sludges to be Handled with Chemical
Treatment Systems: Mineral Addition to Aeration
Basin for Removal of Phosphorus 37
Additional Sludges to be Handled with Chemical
Treatment Systems: Mineral Addition to Secondary
Effluent for Removal of Phosphorus 38
Estimate of Lime Sludge Quantities 40
Estimate of Alum Sludge Quantities 41
Estimate of Iron Sludge Quantities 42
Example Cost Comparison of Disinfection Alternatives
for a 5 mgd Plant 50
Environmental Effects of Chemical Discharges 53
Chemical Treatment Labor Requirements 55
Types of Chemical Feeders 72
Compatible Materials for Piping and Accessories of
Commonly Used Chemicals 94
Materials Suitable for Caustic Soda Systems 95
vi
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FIGURES
Number , , .. • ..,'''' Page
1 Potential Lime Application Points for Phosphorus
Removal ..... . . ..•. „ .... . 23
2 Lime Dosage as Related to Wastewater Alkalinity .... 28
3 Typical Phosphorus Reduction with Alum 29
4 Chemical Feeding System Schematic ..... 57
5 Typical Dry Feed System0 ................ 59
6 Positive Displacement Rotary Feeder 61
7 Oscillating Hopper or Universal Volumetric Feeder ... 62
8 Volumetric Belt Type Feeder ............... 64
9 Typical Helix or Screw Type Volumetric, Feeder (courtesy
of Wallace & Tiernan, Division of Pennwalt Corporation) 65
10 Pivoted .Belt Gravimetric Feeder 66
11 Rigid Belt Gravimetric Feeder 68
12 Typical Solution teed System. ............. 69
13 Positive Displacement Pumps . ....... 71
14 Illustrative Lime Feed System for Wastewater Coagulation 77
15 Typical P.aste-Type Slaker... . ............. 78
16 Typical Detention-Type Slaker 79
17 Alternative Ozonation Systems ............. 81
18 Typical Ozone Contact Basin Using Porous Diffusers . . 82
19 Manual Dry Polymer Feed System ............ 84
20 Automatic Dry Polymer Feed System ........... 85
,21 Typical Positive-Negative Pneumatic Conveying System . 89
22 Typical Bulk Storage Tank . . . . . . .... 91
23 Alternative Liquid Feed Systems for Overhead Storage . 92
24 Alternative Liquid Feed Systems for Ground Storage . . 92.
vii
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SECTION 1
INTRODUCTION
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SECTION 1
INTRODUCTION
PURPOSE OF THE MANUAL
The purpose of this manual is to assist wastewater treatment plant
operators in the proper use of commonly used chemicals in wastewater treat-
ment processes. Emphasis has been placed on providing practical guidance
on the use of chemicals to overcome temporary operational problems or to
upgrade performance without extensive design work or plant modifications.
The manual specifically addresses:
• The use of chemicals as a temporary aid in solving operational
problems.
• Selection of chemicals to be used in terms of treatment
efficiency, cost and other considerations.
• Selecting points for injection of the chemicals.
• Determining proper chemical dosages.
• Sludge considerations associated with chemical additions.
• Identification of equipment for proper feeding and handling
of chemicals.
• General information on each chemical including uses, available
forms, commercial strength, cost, safety considerations, feeders,
storage, handling materials and major manufacturers.
While chemical addition may be helpful in many wastewater treatment
processes, it must be recognized that many situations presented in the manual
are indications of problems associated with overloading or weaknesses
in process control. Short term correction using chemicals may be necessary,
but the condition causing the problem also must be corrected. CHEMICALS
SHOULD NOT BE USED AS A SUBSTITUTE FOR GOOD PLANT OPERATING PROCEDURES.
Some problems in plant operation may be beyond the ability of the oper-
ator to control and are too detailed to be presented adequately in this manu-
al. The operator should learn to identify and define these problems through
experience and the use of references provided in this manual. Plant modifi-,
cations and installation of_chemical storage, handling, and feed equipment,
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as noted in this publication, generally should not be performed by the opera-
tor without the aid of a qualified consulting engineer. Most modifications
require an engineering analysis of the problem and a detailed engineering de-
sign of the change. *
MANUAL ORGANIZATION
In order to simplify the manual and maximize its potential use as a
reference guide, the manual has been organized into five sections plus an
Appendix. The sections may be used independently or in combination depending
on the operator's background and need. Each section is preceded by a quick
reference index to help the operator locate specific information quickly and
easily. Each section is followed by a separate list of references which
provide more detailed information relative to that section.
Section 1 INTRODUCTION
The purpose and organization of the manual, along with an
example of the use of the manual are described in this
section.
Section 2 PLANNING AND EVALUATING PLANT EFFECTS
The optimum use and efficiency of many chemicals are inter-
related with such factors as wastewater pH and tempera-
ture, the point at which the chemical is added in the
treatment train, chemical dosage, and the physical opera-
tion of the treatment facilities. This section of the
manual discusses these factors and provides guidance on
planning and evaluating plant effects when chemicals are
added to various treatment processes.
Section 3 SELECTING CHEMICALS FOR USE
This section describes^general factors to consider in
selecting chemicals including effectiveness, cost, reli-
ability of supply, sludge considerations, compatibility
with other treatment processes, and environmental effects.
Section 4 FEEDING AND HANDLING SYSTEMS
During the decision-making process of which chemical to
use, the operator may need information on chemical feed-
ing and handling systems. This section contains basic
information on dry, solution and gaseous feed systems
as well as special requirements for certain chemicals.
Various types of control systems for chemical feeders
also are described.
Section 5 PROBLEMS WHICH CAN BE SOLVED BY CHEMICAL ADDITION
This section of the manual serves primarily as a trouble-
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Appendix
shooting guide to help identify problems which can be
solved by the addition of chemcials. Problems are identi-
fied by the treatment process where the problem would
occur. A solution is provided for each problem, along
with a list of possible chemicals for solving the problem,
advantages and disadvantages of each chemical, and poten-
tial application points. The section is preceded by an
INDEX OF PROBLEMS which serves as quick reference to
locating problems with various treatment processes.
INFORMATION ON CHEMICALS
General information on each chemical is proyided in this
section, including uses of the chemical, trade names,
available forms, commercial strength, feeders, storage,
safety considerations, approximate cost, acceptable
handling materials, and major chemical manufacturers. For
easy reference, the chemicals are arranged in alphabetical
order. Because it is not possible or practical to iden-
tify all manufacturers of each chemical, the operator is
encouraged to add his own local supplier to the list wher-
ever .possible. . - -
USE OF THE MANUAL
To give the operator a good basic understanding of the manual and its
format, .the following-provides a simplified, step-by-step example on how the
manual might be used. .. , :.',..-,
Example Situation
A 5-mgd trickling filter plant normally uses sodium hypochlorite for
disinfection of its effluent. The plant is equipped with a ROTODIP Feeder
for application of the sodium hypochlorite. Because the plant is isolated
from any large cities, the operator normally stores large quantities (several
months' supply) of the disinfectant on-site at the plant to minimize
shipping problems and chemical costs. However, the effluent lacks sufficient
chlorine residual, even with relatively high chlorine, dosages. The operator
suspects that the sodium hypochlorite supply may be losing its disinfection
power because of long-term storage. As a result, the operator is considering
the use of other chemicals for disinfection.
Steps to Problem Solution
1. Using the index to Section 5 (page 104), the operator locates the
DISINFECTION process on page 124.
2. The operator turns to page 124 and identifies several possible chemicals
which may solve the problem. 'Examining the advantages and disadvan-
tages of each chemical, the operator notes the following:
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• CHLORINE GAS may be feasible but expensive for a plant of this
size.
• SODIUM HYPOCHLORITE (as currently being used) is economical for
small plants but deteriorates more rapidly than some other chlorine
forms.
• CALCIUM HYPOCHLORITE is more stable and has more available
chlorine than sodium hypochlorite, and it is economical, for small
plants.
• CHLORINE DIOXIDE is expensive and must be generated on-site.
• OZONE also is expensive, leaves no residual and must be generated
on-site.
3. Upon assessing these advantages and disadvantages, the operator is
able to see that it may be possible to use CHLORINE GAS, CALCIUM
HYPOCHLORITE, or continue to use SODIUM HYPOCHLORITE with some
adjustments in plant operations.
4. Faced with the uncertainty of which chemical to use, the operator
checks Section 3 to find out other factors which may influence the
choice of chemical. He notes that EFFICIENCY, COST, and RELIABILITY
OF SUPPLY will be important considerations.
5. If the operator is unfamiliar with the EFFECTIVENESS aspects of
chlorine and chlorine compounds he would refer to Section 2 for more
information.
6. To evaluate chemical COSTS, the operator would determine the pounds
per day of each chemical required. Referring to the APPENDIX index
(Page A-2) the operator checks for more information on each chemical:
CHLORINE
CALCIUM HYPOCHLORITE
SODIUM HYPOCHLORITE
Page A-13
Page A-9
Page A-36
Assuming a 10 mg/1 chlorine dosage and a plant flow of 5 mgd, the
operator makes the following dost comparison:
CHLORINE
• 10 mg/lx 8.33 x 5 mgd = 417 Ib/day
• From page, A-l3, cost = $195 - $230/ton
• 417 Ib/day x ton/2000 Ib x $230/ton = $48/day
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CALCIUM HYPOCHLORITE (65%)
^ 10 mg/1 x 8.33 x 5 mgd
vJ • D J
642 lb/day
• From page A-9, cost = $0.70/lb
• 642 5lb/day x $0.70/lb = $449/day
SODIUM HYPOCHLORITE (12%)
0 From page A- 36, cost = $0.40-$0.90/gal
• 348 gal/day x $0.90/gal = $313/day
NOTE - This is NOT a complete cost comparison and only involves the cost of
chemicals. It does not include feeding and handling costs which could
make a considerable difference in overall plant costs. For example,
chlorine gas itself may be very inexpensive but feeding, handling and
storage facilities may make it more expensive than other chlorine forms.
7. Referring to the APPENDIX, the operator identifies and contacts major
manufacturers to verify chemical COSTS and the RELIABILITY OF SUPPLY
in the local area.
8. Again studying the APPENDIX, the operator notes relevant information
on the storage, feeding, handling and safety aspects for each of the
chemicals under consideration. In particular, the operator notes
the following: .
• CHLORINE —- requires a gas feeder (which the plant does not have)
and special safety precautions that will require additional equip-
ment expenditures. He makes a more detailed assessment of chlorine
feeders after referring to the text in Section 4.
• CALCIUM HYPOCHLORITE --is corrosive and must be stored carefully,
but can be fed with a ROTODIP Feeder — the same feeder already
being used for sodium hypochlorite. To make sure there is not
other important information on feeding calcium hypochlorite, the
operator checks Section 4.
9. Based on the information gathered by the operator, a reasonable com-
parison between the alternative chemicals has been made taking into
account:
• Cost
• Effectiveness
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• Safety
• Storage
• Feeders
• Reliability of Supply
Since not all of these factors will be equally important, the
operator must consider circumstances specific to the treatment plant
before making a final choice on the chemical to use.
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SECTION 2
PLANNING AND EVALUATING PLANT EFFECTS
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• SECTION 2
PLANNING AND EVALUATING PLANT EFFECTS
QUICK REFERENCE INDEX OF SUBJECTS
Subject Page
TREATMENT EFFICIENCIES 8
Disinfection ............ ....... 8
Coagulation • • 9
Precipitation of Heavy Metals • 16
Sludge Conditioning 16
SELECTING POINTS FOR CHEMICAL ADDITION . 17
Chemical Addition for Increased SS and BOD Removal 21
Chemical Addition for Phosphorus Removal :..... 22
GUIDANCE ON CHEMICAL DOSAGES .24
Disinfectants 24
Coagulants 27
Coagulant Aids 30
Filter Aids . . . 30
pH Adjustment . ., , . . . • • • - • • • •. . • • ... • • • 30
Sludge Conditioning 31
Chemicals for Other Uses ........ 34
SLUDGE CONSIDERATIONS 34
Sludge Quantities . . . -. . . . -. •. 34
Sludge Processability 39
Sludge Disposal '.'..'. 43
REFERENCES ' « 45
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SECTION 2
PLANNING AND EVALUATING PLANT EFFECTS
Most often, the use of chemicals in wastewater treatment is related to
one or more of the following major applications:
• Disinfection
• Coagulation and flocculation
• Precipitation of dissolved substances
• pH adjustment
• Sludge conditioning
Because there are large variations in wastewater composition from plant to
plant, it is impossible to present precise predictions on how a particular
plant or process will be affected by the addition of chemicals to the treatment
scheme. The optimum use and efficiency of many chemicals is interrelated
with such factors as wastewater pH and temperature, the point at which the
chemical is added d,n the treatment train, chemical dosage, and the physical
operation of the treatment facilities.
This section of the manual will address these factors and provide
guidance on planning and evaluating plant effects when chemicals are added
to various treatment processes. THE OPERATOR IS REMINDED THAT CONSIDERATION
MUST BE GIVEN TO THE EFFECTS OF CHEMICAL ADDITION ON SUBSEQUENT TREATMENT
PROCESSES AND OVERALL PLANT OPERATIONS. IF THE OPERATOR IS NOT COMPLETELY
FAMILIAR WITH TECHNIQUES DESCRIBED IN THIS SECTION, THE SERVICES OF A
CONSULTANT ARE HIGHLY RECOMMENDED.
TREATMENT EFFICIENCIES
Disinfection
Although there are other chemicals which can be used for disinfection,
only the most commonly used chemicals will be discussed, including liquid-gas
chlorine, hypochlorites, chlorine dioxide and ozone.
When chlorine is added to water, several reactions occur which result in
the formation of hypochlorous acid (H0C1) and hypochlorite ions (OC1~).
Table 1 shows the distribution of these two species at various pH values.
As illustrated in the table, low pH values favor the formation of HOC1
which is a much more effective germicide than OC1~. Because liquid-gas
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chlorine tends to lower the pH, and hypochlorites such as sodium hypochlorite
and calcium hypochlorite tend to raise pH, the residual formed by liquid-gas
.chlorine would be a more effective germicide in poorly buffered waters.
There are four major factors which may have an adverse effect on the
germicidal efficiency of chlorine:
• The presence of ammonia and organic nitrogen
• High pH (above 7.5)
» Low wastewater temperature
• Insufficient chlorine dosage or contact time. • --- •
In practice, the germicidal efficiency of chlorine dioxide in the neutral
pH range is about the same as that of chlorine. However, the efficiency of
chlorine dioxide is increased when the pH is. raised above 8.5.
Ozone is a rapid and highly effective disinfectant capable of destroying
bacteria as well as viruses. Unlike chlorine, the effectiveness of ozone is
relatively independent of pH and temperature.
TABLE 1 .''... -, -.
Distribution of HOC1 and OC1~ with pH
Percentage of Total Free Chlorine as:
pH HOC1 -OC1~
6.0 . 96.8 3.2
7.0 - 75.2 .24.8
;7.5 49.1 50.9
8.0 23.2 76.8
9.0 2.9 97.,1 V
Coagulation
The chemicals most commonly used as coagulants in wastewater treatment
are lime {Ca(OH)2}, alum {AlaCSOOs • 14H20}, ferric chloride {FeCl3}, ferrous
sulfate {FeSOif}, ferric sulfate {Fe^SOO 3^ and sodium aluminate
{Na2Al204 • 3H20}. Coagulant aids most often used include polymers and
bentonite clay. These coagulants and coagulant aids are added to wastewaters
primarily to enhance removal of suspended solids and phosphorus, but also
to reduce heavy metal concentrations and improve disinfection. The choice
of specific coagulants and coagulant aids depends on the nature of the solid-
liquid system to be separated, and particularly on the pH of the wastewater.
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Proper choice of chemical coagulants can be best determined by
laboratory testing. This testing should be extensive enough to permit
evaluation of different chemicals and combinations of chemicals and to
determine an approximate dosage. Laboratory test results usually cannot
be applied directly to the actual plant situation, since plant hydraulics
are not simulated in the laboratory. The chemical or combination of
chemicals which appears most favorable in the laboratory should be further
evaluated in a pilot-scale test.
For enhanced suspended solids and BOD removal , Coagulants can be add-
ed to primary or secondary clarifiers. Table 2 shows clarifier performance
before and after chemical addition, and illustrates considerable variation
in BOD and SS removals. However, the greatest improvement resulting from
polymer addition occurs where the existing clarifier performance is poor.
The variations shown make it difficult to project the expected improvement
due to chemical addition at a specific treatment plant. Pilot plant tests
or full scale plant trials generally are necessary for such predictions to
be made accurately. As guidance, however, Table 3 provides a summary of
typical removal efficiencies for both activated sludge and trickling filter
plants when polymer is added to the primary clarifier.
Lime addition to primary clarifiers for phosphorus removal has been used
in many locations. In all cases, significant improvements in both SS and BOD
removal also were noted, as shown in Table 4.
In many cases where chemicals are added to secondary processes, the
principal goal has been phosphorus removal. Very often the addition of iron
and aluminum salts used for phosphorus removal can also improve greatly the
performance of the secondary clarifier depending on the dosage applied,
point of chemical addition and the flocculating characteristics of the system.
Several examples of typical clarifier performance before and after chemical
addition are shown in Table 5.
When the biological and chemical processes are combined, the coagulant
may be added either ahead of the primary clarifier or directly to the aera-
tion tank of an activated sludge system. When added ahead of the primary
clarifier, alum, iron or lime may be used; when added directly to the aera-
tion tank, iron or alum salts are used. In the approach which separates the
physical- chemical processes from biological treatment, any of the above
coagulants may be added to the secondary effluent with subsequent settling
downstream.
ms in which chemical coagulation is combined with the b :' o Logi •••> '
process are capable of phosphorus removal rates of 75-85 percent. This would
be equivalent to effluent phosphorus concentration of 1-2 mg/1. Subsequent
filtration of this effluent may reduce the phosphorus concentrations to 0.5
mg/1 if the coagulant dose is proper. In systems using chemical coagulation
of secondary effluent as a separate process, lower phosphorus concentrations
on the order of 0.05 mg/1 can be achieved. More detailed information on the
use of chemicals solely for phosphorus removal is described in the Process
10
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--, CN VO CM
00 ^ -H
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a
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o r-- oo r~
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a)
P.
00
— •. co m o
00 rH rH ' CN
o
a co
O P-l
•H ~~
4J CO
s~^
*O *^
cu oo cu
3 rt fr
•S -a e i
4J CU CU CU
0 CJ S pj
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U M CO (=1
^-^ PJ CU O
MM
CN Q) H
,
1 1 1
1 1 I
4-1
0
cu
CJ
Mill
cu i i i
P.
rH | | 1
"So ' ' '
e
CJ
W f3 rH
rH CD CO
eg s c
l^ C^ Q
cu o e
P4 cu <-H cu
^ M rH rH
rH rH r-j
12
» »
CU
00
rH
co
4J
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,2
4-1
CJ
cO
cu
4-1
1
1
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Js
iH
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00
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I
1
CO
-------
TABLE 3
Polymer Addition to Primary Clarifier
Primary Clarifier
Total Plant
Treatment Process
Activated Sludge
Trickling Filter
Activated Sludge
Percent Percent Percent Percent
Removal Removal Removal Removal
Before After Before After
Polymer Polymer Polymer Polymer
Coagulant Dose Addition Addition Addition Addition
mg/1 BOD SS BOD SS BOD
Purifloc
A-21 1 26 — 48 — 83
Purifloc
A-21 1 23 43 33 76 79
Purifloc
A-23 0.21 31 31 46 51 79
SS BOD
90
72 85
85 83
SS
84
89
13
-------
TABLE 4
Lime Addition to Primary Clarifier
Location
Richard
Hill, Ontario
Lime Added
Percent Removal
in Primary Before
Lime Addition
Percent Removal
in Primary After
Lime Addition
175
21
37 71
Remarks
Duluth,
Minnesota
Rochester,
Nex* York
Lebanon,
Ohio
mg/1 CaO BOD
75 50
125 55
100
145
SS BOD
70 60
70 75
50
66
SS
75
90
80-90
74
—
Jar tests
Pilot pla:
77 Full-scale
Central Contra 378 46
Costa, Calif. 303 37
71
71
74
69
79 Full-scale
76 Full-scale
14
-------
TABLE 5
Effect of Chemical Treatment on Secondary
Clarifier Performance
Kfflucnt IIODg Effluent SS Effluent HODS Effluent SS Total
Location
Kichardnon, Texas
Chapel Hill,
North Carolina
Pennsylvania Stale
Cincinnati,
Ohio
Lebanon,
0)iio
Minneapolis,
MitincMuU
Madison,
Wi.-consin
I'niversity. Park,
Pennsylvania
RluomJnglon,
Illinois
Blue Plains,2
Washington, D.C
Sundusky, Ohio
Michigan City,
Indiana
Guelph, Ontario
Pal melto. Florida
Type of Plant
Trickling filler
sld. rate
Trickling filler
high rate
.Conventional
activated sludge
Activated sludge
(1 00 gpd pilot)
Activated sludge
(0.1 1 mgd pilot)
Trickling filter
low rate
—
Trickling filter
Activated sludge
.Trickling filter
Modified Activated
sludge
Conventional
activated sludge
Conventional
activated sludge
Conventional
activated sludge
Trickling filter
Location of Chemical and (or COD) Before Before (or COD) After After
Chemical A'ddition Dosage Chemical Addition Chemical Addition Chemical Addition Chemical Additi
Before final willing
Before final settling
Aerator effluent
Aerator
Final clarifier
- Before final settling
Before final settling
Before final settling
Aerator
Before final settling
Before final settling
Aerator
Aerator
Aerator
Before final settling
AI/PMole
Dosage 1.6/1
Al/P Mole
Dosage 1 .6/1
Al/P wt.
Ratio 3/1
10mg/IAl3+
Add lime to
raise pH=9.4-10.9
720 mg/1
Ca(OH)2
200 mg/1
' Alum
)60 mg/1
Alum
46 mg/1
Na2Al2°4
33.9 mg/1 Fe3+
+0.7 mg/1
Purifloc — A23
25-30 mg/1 Fe3+
+0.5 mg/1
Purifloc - A23
26 mg/1 Alum
50 mg/1 Alum
60 mg/1 Alum
80 mg/1 Alum
89 mg/1 Alum
SOrng/1
Alum
60 mg/1
Alum
100 mg/1
Alum
45 mg/1
Alum
mg/1
20
44
13
(8<«)1
—
83
8-29
18
61
8.8
13.0
47
38
68
46
50
9
13
26
—
mg/1
IS
64
26
(9556)1
43.5
—
— :
31
95
12.7
49.6
48
39
53
41
57
24
19
38
30-40
mg/I
<5
15
9
(9256)1
—
27
1 .8-2.9
6
23
5.0
3.3
40
27
. 25
41
30
2
9
14
—
mg/1
<7
34
22
(96*)!
16.5 /
— -
—
19
8
8.6
16.0
43
36
36
31
31
• -.
15
7
22
10
Phos.
ion Removal
percent
95
82
86
94
•
•'•-"'86
98.7
96.4
93.4
~ -
—
—
—
—
80
92.2
87
—
* Percent removal.
2j)ata arc monthly average.
15
-------
Design Manual for Phosphorus Removal (Reference 4). The manual provides
a comprehensive discussion of phosphorus removal methods involving chemical
precipitation, design information, and operating procedures aimed at removal
of phosphorus to comply with water quality standards.
Precipitation of Heavy Metals
Because many heavy metals form insoluble hydroxides at pH 11, lime
coagulation results in a significant reduction in metal concentrations.
Except for mercury, cadmium, and selenium, lime coagulation at pH 11 can
remove at least 90 percent of most heavy metals. Higher removal efficiencies
occur when lime coagulation is followed by filtration.
Sludge Conditioning
In most cases, it is not practical to dewater sludge, especially
secondary sludge, without conditioning. The conditioning step can take the
form of either a chemical or a physical process. Chemical methods include
the use of organic and inorganic flocculating chemicals as well as chlorine
oxidation. The physical processes include the use of heat and freezing to
change the characteristics of the sludge. Only the use of chemicals for
conditioning will be addressed in this section, since the physical processes
are outside the scope of this manual.
The most common chemical conditioning method is the use of ferric chloride
alone or in combination with lime. Lime alone is a fairly popular conditioner
for raw primary sludge and ferric chloride alone has been used for conditioning
activated sludges. Lime treatment to a pH of 10.4 or above has the added
advantage of providing a significant degree of disinfection of the sludge.
Other inorganic chemicals used include ferrous salts and aluminum salts.
Organic polymer coagulants and coagulant aids have been developed in
the past 20 years and are rapidly gaining acceptance for sludge conditioning
since they accelerate the removal of liquid from sludge particles during
dewatering. There are three basic types of these polymers:
1. Anionic (negative charge) - serve as coagulant aids to inorganic
A1+++ and Fe+'H- coagulants by increasing the rate of flocculation,
size, and toughness of particles. Because of improved flocculation
with anionic polymers, smaller dosages of alum or other primary
coagulants usually are required.
2. Cationic (positive charge) - serve as primary coagulants alone or
in combination with inorganic coagulants such as alum, or even
with other anionic and nonionic polymers. When used alone,
strongly cationic polymers react much more slowly than inorganic
coagulants, and therefore require longer mixing times.
3. Nonionic (equal amounts of positively and negatively charged groups
in monomers) - serve as coagulant aids in a manner similar to that
of both anionic and cationic polymers. Nonionic polymers are generally
16
-------
reliable coagulant aids since treatment is usually .less sensitive
to minor overdoses.
Usually, cationic polymers have the greatest application to waste sludge .'
dewatering. In some cases, cationic polymers and ferric salts together have
been used effectively. For tertiary waste treatment sludges containing
aluminum, ferric, or lime sludges, anionic polymers are often effective.
With proper chemical conditioning, the sludge moisture can be reduced
from 90 - 96 percent to 64 - 80 percent, depending on the nature of the
solids to be dewatered. The conditioning step greatly increases the rate
of dewatering by changing the chemical and physical nature of the sludge.
However, because of the differences in sludges and their conditioning
properties, it is common practice to run either a Buchner funnel or a
filter leaf test to determine the best flocculating chemical. These tests
help to estimate the rate at which the solids can be filtered and the final
moisture content the cake will attain. Various chemicals and combinations
of chemicals can be tried in the laboratory to establish the full—scale
chemical dosage. Laboratory tests generally will define the chemical
dosage and operating characteristics of a dewatering unit within 15 percent
of the range established for the full-sized facility.
The use of polymers and other conditioning chemicals has allowed more
sludge types to be dewatered more efficiently by centrifuges, vacuum filters
and pressure filters. Table 6 shows typical solid bowl centrifuge sludge
cake characteristics and the effect of various polymer dosages on percent
solids recovery. The degree of solids recovery can be controlled over wide
ranges depending on the amount of coagulating chemical applied. When polymers
are used, however, a wetter sludge cake usually is produced because of the
additional fines capture. Table 7 summarizes design and performance data
for vacuum filtration of different types of sludges using different chemical
conditioners. Table 8 summarizes similar data for pressure filtration using
various conditioners.
SELECTING POINTS FOR CHEMICAL ADDITION
In many applications, proper points for chemical addition are well
defined and easily recognized by the operator. For example, wastewater
disinfection is the last step in a secondary plant, and disinfectants are
added directly to the secondary effluent prior to discharge from the plant.
On the other extreme, it is generally more difficult for an operator to
determine the best point for adding coagulants to"enhance suspended solids,
BOD, or phosphorus removal. The remainder of this section ,will describe some
of the more important factors to consider in selecting points for coagulant
addition. Section 5 of this manual provides more general guidance on
application points for other chemicals and processes used in wastewater
treatment. "
17
-------
TABLE 6
Typical Solid Bowl Centrifuge Performance
Sludge Type
Raw or digested primary
Raw or digested primary, plus
trickling filter humus
Raw or digested primary, plus
activated sludge
Activated sludge
Oxygen activated sludge
High-lime sludges
Lime classification
Design
Assumption
no conditioning
5-15 Ibs polymer/ton
no conditioning
5-20 Ibs polymer/ton
no conditioning
5-10 Ibs polymer/ton
3-5 Ibs polymer/ton
no conditioning
no conditioning
Percent
Solids Percent
to Solids
Centrifuge Recovery
28-35
20-30
15-30
8-9
8-10
50-55
40
70-90
80-95
60-75
80-95
50-65
80-85
80-85
90
70
18
-------
TABLE 7
Typical Design and Performance Data for Vacuum Filters
Sludge Type
Primary
Primary + FeCl3
Primary +
low lime
Primary +
high lime
Primary + WAS
Primary +
(WAS + Fegi3)
(Primary +
+ WAS
Waste activated
sludge (WAS)
WAS + Fed,,
Digested primary
Digested primary
+ WAS
Digested primary
+ (WAS + FeCl3)
Tertiary alum
Design Assumptions
Thickened to 10% solids
Polymer conditioned
85 mg/1 FeCl3 dose
Lime conditioning
Thickening to 2.5% solids
300 mg/1 lime dose
Polymer conditioned
Thickened to 15% solids
600 mg/1 lime dose
Polymer conditioned
Thickened to, 15% solids
Thickened to 8% solids
Polymer conditioned
Thickened to 8% solids
FeCl3 and lime conditioned
Thickened primary sludge
to 2.5%
Flotation thickened WAS
to 5%
Dewater blended sludges
Thickened to 5% solids
Polymer conditioned
Thickened to 5% solids
Lime + FeCl3 conditioned
Thickened to 8-10% solids
Polymer conditioned
Thickened to 6-8% solids
Polymer conditioned
Thickened to 6-8% solids
+ lime conditioned
Typical
Loading Percent Percent
Rates, Solids Solids
(psf/hr) to VF VF Cake
8-10
10
4-5
1.5
2.5-3.5
1.5-2.0
7-8
3.5-6
2.5-3
10 25-38
1.0-2.0 2.5
15
15
3.5
6-8
6-8
15-20
32-35
28-32
16-25
20
15-20
15
15
8-10 25-38
14-22
16-18
Diatomaceous earth
precoat
0.4 0.6-0.8 15-20
19
-------
TABLE 8
Typical Performance Data for Pressure Filters
Sludge Type
Primary
Primary + FeCl3
Primary + 2 stage
high lime
Primary + WAS
Primary + (WAS + FeCl3)
(Primary + FeCl3) + WAS
WAS
WAS + FeCl3
Digested primary
Digested primary + WAS
Digested primary +
(WAS + FeCl3)
Tertiary alum
Tertiary low lime
Sludge Conditioning
5% FeCl3, 10% Lime
100% Ash
10% Lime (200 Ib/ton)
None
5% FeCl3, 10% Lime
150% Ash
5% FeCl3, 10% Lime
10% Lime
7.5% FeCl3, 15% Lime
250% Ash
5% FeCl3, 10% Lime
6% FeCl3, 30% Lime
5% FeCl3, 10% Lime
100% Ash
Typical
Cycle
Length
(hrs)
2
1.5
4
1.5
2.5
2.0
3
4
2.5
2.0
3.5
2
2
1.5
Percent
Solids
to
Pressure
Filter
5
4*
7.5
8*
8*
3.5*
5*
5*
8
6-8*
Percent
Solids
Filter
Cake
45
50
40
50
45
50
45
40
45
50
45
40
45
50
5% FeCl3, 10% Lime
10% Lime
None
6
1.5
6-8*
4*
8*
40
35
55
* Thickening used to achieve this solids concentration.
20
-------
Chemical Addition for Increased SS and BOD Removal
The most favorable point for addition of chemical coagulants and floe-
culants may be influenced by the form in which phosphorus is present. Raw
sewage in primary tanks, for example, usually contains polyphosphates which
.are later broken down to orthophosphate by biological treatment. Polyphosphates
in relatively high concentrations (more than 1 mg/1 of P20s) are capable of
interfering with coagulation and sedimentation. Orthophosphate compounds
produce no interference with normal coagulation and sedimentation. If the
amount of polyphosphate interference in the primary state is great, then
chemical addition should follow conversion of this material to orthophosphate.
Adding chemicals to the primary elarifier is an effective upgrading
procedure for a secondary plant when:
1. Wastewater flow is intermittent or vari'es greatly.
2. Space available for additional clarification facilities is limited.
3. Industrial wastes that would interfere with biological treatment
are present.
4. Plant is hydraulically and/or organically overloaded.
5. Improvements in existing treatment performance are required as
an interim measure before the addition of new facilities.
When considering the addition of chemicals to primary elarifiers, IT IS
IMPORTANT TO BE AWARE OF THE EFFECT ON SUBSEQUENT TREATMENT UNITS. The
increased removal of SS and BOD from raw wastewater can affect the downstream
biological process in a number of ways. If the BOD load to the aeration
basin falls below 0.25 to 0.35 Ib BOD/lb MLVSS/day for long periods of time,
nitrification can develop in the aeration basin. This can reduce the total
oxygen demand of the effluent, but will cause an added oxygen demand on the
aeration facility because the oxidation of one pound of ammonia nitrogen
requires about 4.6 pounds of oxygen.
A lower aeration basin loading will usually require more careful sludge
management to ensure stable operation of the aeration basin. However, the
quantity of excess activated sludge generated under these reduced loading
conditions will be much less than that generated under normal loading
conditions. This may be considered an added advantage of adding chemicals
to the primary elarifier, if the additional fines captured chemically do
not seriously degrade the quality of the primary sludge.
Whenever possible, some flexibility should be built into the plant
design to allow for different points of chemical addition, since this
aspect may severely affect costs and process efficiencies. There may be
some question as to where coagulants such as alum or iron salts should be
added to the treatment scheme, when improved BOD, suspended solids and
phosphorus removal is the primary goal. As a general rule, where no flash
21
-------
mix tanks are provided, alum should be added at a point where turbulence is
present to insure rapid mixing. Addition of alum directly to an aeration
tank will not adversely affect the biological process, but some build-up of
aluminum compounds in the recirculated sludge may occur.
Some studies have indicated that the turbidity of the final plant
effluent may be increased when alum is added to the aeration system.
This may occur when the alum dosage is high enough that it reduces the pH
below the optimum pH for good alum flocculation, resulting in an increase
in pinfloc in the final effluent.
LIME ADDITION MAY NOT BE FEASIBLE FOR UPGRADING ACTIVATED SLUDGE
SECONDARY CLARIFIERS BECAUSE OF THE POTENTIAL ADVERSE EFFECT OF RECIRCULATED
LIME SLUDGE ON MIXED LIQUOR MICROBIAL CHARACTERISTICS. Lime addition to
either trickling filter or activated sludge secondary clarifiers will require
pH adjustment of the effluent before discharge to the receiving waters.
Lime addition to primary clarifiers may be used, if consideration is given
to controlling the pH within acceptable limits for the subsequent processes,
and to changes in sludge characteristics and handling requirements.
The chemical addition of lime or metallic salts at various points
in a wastewater treatment plant usually results in increased solids weight
and/or sludge volume. Therefore, sludge piping, pumping and process units
should be large enough to handle the increased sludge quantities. Sludge
considerations associated with the use of chemicals at various points in
the treatment process are covered in a later section of this chapter.
Chemical Addition for Phosphorus Removal
As illustrated in Figure 1 -,. there are several points where lime can be
added to the treatment scheme for phosphorus removal. Lime may be added
before the primary sedimentation tank in a biological treatment plant.
Because an excessively high pH would interfere with the biological process,
lime addition to the primary sedimentation tank ahead of an activated sludge
system is limited to a pH of about 9.0. However, it is not unusual for
2-3 mg/1 of phosphorus to remain soluble at this limited pH. Additional
phosphorus removal may be achieved by using aluminum or iron addition in
the aeration tanks or final sedimentation tank. Another advantage ;to the
use of lime in primary treatment is the increase in organic and suspended
solids removal in the primary sedimentation tank. This, in turn, decreases
the load on the aeration system.
A second alternative is lime treatment following biological treatment.
Phosphorus removal from the secondary effluent assures that there will be
adequate phosphorus to meet the needs of the biological floe under aeration.
In addition, the biological system breaks down many of the complex phosphates
to a form which is more easily removed by chemical treatment. However, pH
of the returned sludge could affect biological treatment and should be
considered.
22
-------
LIHE
RAU., .„ . MIXING
WASTE- & *•
WATER COAG
1 ... ,; '!•; - .• .< }....,' • • -• '- • • .--
"«" '._-:.._,. ,!^N COMPLETE •-•
> WASTE- i BIOLOGICAL • »•
WATER ; ' TREATMENT '
i SLUDGE
POLYMER
^UHFN ' LIME
NEEDED) I 1
f $
RAW g» ""ING
WAS It- & .. . B»a
WATER COAG
i i >
SLUDGE
RECIRCULATION
CHEMICAL
REUSE
EFFLUENT
SLUDGE: .--.-, - . -- • :•;••• : ; „ '••.-;•?
1 *:.•-•-. ' --••;•: •'••.• ••••
LIME
i- •• - • • - •-,..-...,
: .-•-•,•-. : ?.:•. - - - ' : . '
MIXING ' - ' EFFL"ENT V
1 ' COAG- ' -; -•"-'•
nAdRAAlfl)AAlAfilM&inAi@^®Affill%^^d^6Affii^^AAAlAAAfai9^fi)idKAAiKti
... ALUM (WHEN NEEDED) . , ' . '
RETURN ACTIVATED .
SLUDGE
,,
-------
Like lime, there are several points where alum may be added to the
treatment scheme for phosphorus removal. Alum may be added before the primary
settling tank, in the aeration tank, or following aeration before final sedimen-
tation. Alum addition before the primary settling tank removes not only
phosphorus, but also removes suspended solids and organics. These removals,
however, require an increased alum dosage to make up for the added demand.
Providing alum addition in the activated sludge aeration tank allows
the usage of the mixing already provided for that system. The best point of
addition for alum in an activated sludge plant may be in the effluent channel
of the aeration basin which carries mixed liquor to the final settling basin.
The turbulence in this channel provides adequate mixing for the chemical.
By adding alum after the biological system, the wastewater is stabilized
and the complex phosphates are put into a form more easily removed by the
chemical." . • '•• .-•-.-.- .-' ----- .... ,...":.•..' il..-'. Ji':
GUIDANCE ON CHEMICAL DOSAGES . , , :i ,..••,; ,:;
' r "s ,
In order to plan adequately for the addition of chemicals to any treatment
process, design considerations should include an estimate of the chemical -i
dosages required. It is not always possible to determine through theoretical
calculations and laboratory tests precise dosages for optimum operating
conditions at the plant. However, Table 9 provides a summary of testing
techniques commonly used for evaluating chemical dosages for various applica-
tions. The table identifies the test name, purpose of the test, and a
reference describing the test procedure. These tests along with the guidance
provided in this section of the manual will help the operator to determine
the general ranges for dosages of chemicals commonly used in wastewater
treatment.
Disinfectants "
The chlorine dosage required for disinfection depends primarily on the
quality of the effluent to be treated. Table 10 provides typical dosages
of chlorine for various levels of treated wastewater. Each plant's precise
requirements, however, also depend on the effluent, the degree of mixing
provided, the detention time available in the contact tank or outfall, and
the most probable number (MPN) requirements of the regulatory agency.
Chlorine dosage normally is controlled by maintaining a chlorine
residual. Regular analyses of bacterial quality should be made and the
target residual adjusted depending on the trend of the results.
For ozone disinfection of secondary effluent, typical dosages range
from 5 to 15 mg/1 for an MPN of 100/100 ml. The amount and characteristics
of suspended solids present in the secondary effluent can affect the
required ozone dosage.
24
-------
., TABLE 9
Techniques for Evaluation of Chemical Dosages
Test Name
Purpose of Test
Jar test
Buchner Funnel ,,
Test , - ;;
Filter Leaf
Test
PH
Chlorine Residual
BOD
Turbidity
MPN Coliform
Proper choice of coagulant and optimum
coagulant dosage
Optimum chemical dosage for
-•' sludge dewatering
Measure .effects of chemical dosages,
; fabrics, and drying time oil vacuum
•. filter yield
Measure acidity or basicity of
wastewater for proper neutralization
and control of. chemical additions
Proper control of chlorine dosage
Control of methanol dosage in
denitrification
Control of filter aid dosage
Control of chemical addition for
disinfection
Reference for
Test Procedures
Ref. 7-Page 256
Ref. 7-Page 258
Ref. 8-Page 109
Ref. 6-Page 460
Ref. 5-Page 512
Ref. 6-Page 318
Ref. 5-Page 520
Ref. 6-Page 543
Ref. 5-Page 518
Ref. 6-Page 132
Ref. 6-Page 875
Ref. 5-Page 524
25
-------
TABLE 10
Chlorine Dosage Ranges
Wastewater To Be
Disinfected
Raw sewage
Raw sewage (septic)
Settled sewage
Settled sewage (septic)
Chemical precipitation effluent
Trickling filter effluent
Activated sludge effluent
Sand filter effluent
Chlorine Dosage
mg/1
6 to 12
12 to 25
5 to 10
12 to 40
3 to 10
3 to 10
2 to 8
1 to 5
26
-------
Coagulants
The quantity of chemical coagulant needed to obtain good coagulation
varies with time and from wastewater to wastewater. Aluminum and iron salt
requirements for good phosphorus removal are generally proportional to the
phosphorus concentration, while lime requirements are determined largely by
the alkalinity of the wastewater. Typical coagulant dosages are:
Aluminum sulfate
Ferric chloride
Lime
Sodium Aluminate
75 - 250 mg/1
45 - 90 mg/1
200 ;- 400 mg/1
75 - 150 mg/1
The lime dosage required to achieve a given pH and turbidity and/or
phosphate removal is primarily a function of the wastewater alkalinity and is
relatively independent of the influent phosphorus concentration. In general,
phosphate removal.increases with increasing pH. Essentially all orthophos-
phate is converted to the insoluble form at pH greater than 9.5. The actual
pH that will be required to precipitate a given amount of phosphate, and
the amount of lime addition that will be required to raise the pH .to the
desired level will vary with the specific wastewater composition. These
parameters should be determined by laboratory jar tests (See Ref. 7,page 256).
Figure 2 illustrates the relationship between alkalinity and the lime dosage
required to achieve a pH of 11. With high alkalinity wastewater, a pH of '9.5
to 10 can result in excellent phosphorus removal. Unless a high pH is used,
waters with low alkalinity (150 mg/1 or less) form a poorly settieable floe.
It should be noted, however, that lime precipitation of phosphorus
may require filtration to insure continuous compliance with effluent require-
ments. Even at a process pH as high as 11.4, high residual phosphorus
may appear in the effluent. Although high pH values insure that virtually
all phosphorus is insolubilized, effluent total phosphorus is determined by
suspended solids removal efficiency. Where the floe is difficult to settle,
filtration can be used to provide the necessary SS and phosphorus removal.
The starting point for the determination of chemical dosages for alum
and other mineral precipitants can be based on phosphorus removal efficiencies
and side reactions. Figure 3 illustrates typical phosphorus reductions with
varying dosages of alum. Since the optimum dosages cannot be calculated readily
because of the complexity of the reactions involved, the laboratory jar test
should be used to determine actual chemical requirements.
Dosage requirements for sodium aluminate are similar to alum. In general,
dosages in the range of 75 to 150 mg/1 will be required. In wastewater
treatment sodium aluminate dosage more often is determined by phosphorus re-
moval requirements than by suspended solids considerations.
Because iron salts react with the natural alkalinity of the wastewater,
the dosage requirements for optimum coagulation using ferric chloride or
. 27
-------
500
1 400
ii
™ 300
I
H
J3
g
w
200
I
I
0 100 200 300 400
WASTEWATER ALKALINITY, mg/1 as
500
Figure 2» Lime dosage as related to wastewater alkalinity.
28
-------
25 -.
T 1—-T T 1 r
20 40 60 80 100 120 140
ALUMINUM SULFATE DOSAGE, mg/1
Figure 3. Typical phosphorus reduction with alum. -
29
-------
ferric sulfate may be in excess of theoretical levels. If natural alkalinity
is not sufficient it may be necessary to add alkalinity in forms such as lime
or soda ash to the wastewater. In addition, the use of iron salts will
result in some pH depression in the wastewater. This effect will vary with
coagulant dosage and wastewater characteristics. As with the other coagulants
discussed in this section, optimum dosages are best determined by laboratory
jar tests.
Coagulant Aids
Coagulant aids or flocculants are often used to enhance the efficiency
of coagulants. Typical dosage ranges for various coagulant aids are shown
below; however, jar testing is recommended to determine optimum dosage.
Bentonite
Activated silica
Polymer
3-20 mg/1
5-25 mg/1 (as (Si02)
0.1 - 0.25 mg/1
Caution should be exercised in using coagulant aids, particularly
polymer, since overdosing can restabilize solids and make them very difficult
to settle out.
Filter Aids
A major element in optimizing filter performance is the use of an
appropriate amount of filter aid (polymer and/or alum).
The amount of filter aid needed increases with lower water temperature,
high flow rates through the filters, and higher applied water turbidities.
The optimum dosage of filter aid is that which causes the maximum desired
filter headless to be reached just as turbidity breakthrough is about to
occur. Too much filter aid shortens the length of filter runs, and too
little will allow turbidity breakthrough before the maximum allowable
headless is reached.
When lime is the primary coagulant, it is usually desirable to use
some alum (5 to 20 mg/1) as a filter aid even when a polymer is used. When
used as a filter aid, typical polymer dosages may range from 0.01 to 0.1 mg/1
depending on turbidity tests of the effluent.
pH Adjustment
One of the most common types of chemical treatment used in wastewater
treatment plants is pH adjustment. Wastewaters that are highly acidic or
highly alkaline are objectionable in collection systems, treatment plants,
and natural streams. pH adjustment is simply the raising or lowering of a
pH to a more desirable value by the addition of chemicals.
30
-------
Alkaline reagents used to treat acidic wastes vary in the quantity of
acid they are capable of neutralizing. For comparison each alkali can be
assigned a "basicity factor." This factor is the weight of a specific alkali
equivalent in acid neutralizing power to a unit weight of calcium oxide (CaO) .
Basicity factors for the more common alkaline reagents are shown in Table 11. : :
To use Table 11, the neutralizing capacity as well as solubility of the chemical
must be considered when comparing alkaline reagents. Also, there is no direct
relation between pH and acidity. In order to adjust the pH of an acidic
wastewater, a titration curve must be constructed. (See Ref. 6) The acidities,- as mg/1
CaCOs, are determined from the titration curve for any desired pH level.
Finally^ to determine the amount of base required to neutralize the wastewater
to a pH of 7.0, the acidity, as mg/1 CaCO^, at the pH 7.0 endpoint must be
known. The concentration factors for the various alkaline reagents shown
in Table 11 can then be used to design the chemical feed system.
In some cases, it may become necessary to adjust the pH of a wastewater
stream downward. Discharge of effluents with pH greater than 8.5 is generally
undesirable and in many cases not allowed. To lower the pH, carbon dioxide
or acid, may be added to the wastewater. As in the case of acid neutralization,
a titration curve is necessary to determine the acid requirements for
neutralizing alkalinity. To neutralize 1.0 mg/1 of alkalinity the dosages
of 100 percent acid required would be:
Sulfuric Acid (I^SOij) 0.98 mg/1
Hydrochloric Acid (HC1) 0.72 mg/1
Nitric Acid (HN03) 0.63 mg/1
Because these acids are available in different strengths, these figures
would need to be adjusted by a dilution factor depending on acid strength.
(Table 11).
Sludge Conditioning , ,
The most common chemical conditioning method for sludge is the use
of inorganic chemicals such as ferric chloride, ferrous salts, lime, or
aluminum salts. More recently, organic polymers have been used. Feed rates
for chemical conditioning ot sludges are extremely variable depending on the
process used, nature of the sludge, and type of chemical. Typical ranges
for dosages are shown in Table 12..
Because of large variations in sludges and their properties, it is
recommended that either a Buchner Funnel or filter leaf test be conducted
to determine the best chemical and optimum dosage. These tests are described
in Reference 7, page 258 and Reference 8, page 109, respectively. Through the use
of these tests , various chemicals and combinations of chemicals can be tried
in the laboratory to establish the full-scale chemical dosages. Laboratory
tests generally will define the chemical dosage and operating characteristics
of a dewatering unit within 15 percent of the range established for the full-
sized facility.
31
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Typical Chemical Dosages for Sludge Conditioning
Sludge Type
FeCl3,
ib/fcpn
dry-. ;.
Solids
Lime,
Ib CaO/ton
Solids
Polymer,
Ib/ton
dry
Solids
Raw primary + waste
activated sludge
40-50
110-300
15-20
Digested primary + waste
activated sludge
80-100
160-370
30-40
33
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Chemicals for Other Uses
There are many other chemicals and uses for chemicals in addition to
those already presented in this section of the manual. Table 13 provides
a summary of uses and average dosages of several chemicals which are
commonly used by operators to solve plant problems. As with other chemical
uses, the operator must consider the effect of these chemicals on subsequent
treatment units.
SLUDGE CONSIDERATIONS
Chemical addition can result in a noticeable difference in overall
sludge characteristics. For example, when lime or metallic salts are added
to processes in a wastewater treatment plant, a new source of sludge is
produced. Depending on where the chemicals are added, increased quantities
of primary or secondary sludges may occur. Also, the ratio of primary to
secondary sludge will be affected by the use of chemicals. For example,
if lime or a mineral salt is added to the primary settling tank, floe
production and solids capture will be increased. Because of this increase
in primary sludge, the ratio of primary to secondary will be increased.
This can result in a noticeable difference in overall sludge characteristics
at the treatment plant. As will be explained in the following paragraphs,
it is not only the quantity, but also the dewatering characteristics of
the sludge that are important.
Sludge Quantities
In chemical precipitation, the pounds of sludge produced per million
gallons of wastewater treated can vary considerably. Data on production of
sludges for chemical treatment at various points in a secondary plant are
summarized in Tables 14 through 16- It is difficult to obtain a true
measurement of sludge quantities in laboratory tests because of solids loss
during decanting and other procedures. It is possible, however, to estimate
the weight of sludge solids by calculating the sum of the expected solids
removal and the precipitation products expected from the chemical dosage
applied. Jar tests generally can be used to obtain the necessary information
for this calculation.
34
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TABLE 13
Chemical Dosage Guide
Chemical
Activated Carbon
Chlorine
Copper Sulfate
Hydrogen Peroxide
Methanol
Ozone
Polymer
Sulfur dioxide
Use
Organics Removal
TF flies and ponding
Bulking sludge
Breakpoint chlorina-
tion (N-removal)
Odor control
Prechlorination
Lagoon algacide
Bulking sludge
Odor control
Denitrification
Odor control
Scale prevention
(in stripping tower)
Improve sand drying
bed
Dechlorination
Average Dosage
250-1,800 Ib/mil gal
0.5-1.0 mg/1 residual
5-60 mg/1
10 mg/1
1 mg/1 residual
2-5 mg/1 '"'
5-10 Ib/mil gal
50-200 mg/1
1-1.5 mg/1 per 1 mg/1 H2S
3 methanol: 1 nitrate-N
1-2 mg/1 (by volume of air treated)
0.5-5.0 mg/1
5-30 Ib/dry ton
1 mg/1 SOo per 1 mg/1 Cl2 residual
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36
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TABLE 15
-, Additional Sludge to be Handled with Chemical Treatment Systems:
Mineral Addition to Aeration Basin for Removal of Phosphorus
Sludge Production
Parameter
Alum Addition to
Aeration Basin*
Conventional With Alum
Secondary Addition
Fe3+Addition to
Aeration Basin
Conventional
Secondary
3+
With Fe
Addition
Level of chemical
addition (mg/1)
0
672
384-820
103-253
1.12
0
Percent sludge solids
Mean 0.91 1.12 1.2
Range 0.58-1.4 0.75-2.0 1.0-1.4
Ib/mil gal
Mean
Range
gal/mil gal
Mean
Range
10-30
1.3
1.0-2.2
1,180 1,059 1,705
744-1,462 218-1,200 1,100-2,035
9,100 13,477 10,650 18,650
7,250-12,300 7,360-20,000 10,300-11,000 6,000-24,000
* MW of Alum: A12(S04>3 • 14H20 = 594
37
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TABLE 16
Additional Sludge to be Handled with Chemical Treatment Systems:
Mineral Addition to Secondary Effluent for Removal of Phosphorus
+3
Sludge
Production Parameters
Level of chemical
addition (mg/1)
Percent sludge solids
Mean
Range
Ib/mil gal
Mean
Range
gal/mil gal
Mean
Range
Lime
Addition
268-450
1.1°
0.6-1.72
4,650
3,100-6,800
53,400
50,000-63,000
Alum
Addition
200
1.0
568
6,810
Fe
Addition
10-30
1.0
507
175-781
6,080
2,100-9,400
38
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There are several computation methods available to estimate sludge
quantities produced by chemical addition. EPA Technology Transfer Process
Design Manual for Phosphorus Removal Qtef. 4)describes several methods and
provides detailed procedures for estimating chemical sludge quantities.
Other procedures are outlined in EPA Technology Transfer Manual, Physical-
Chemical Wastewater Treatment Plant Design (Ref. 10) and are reproduced"
in Tables 17 through 19 in this manual for easy reference. The basic
equations needed to perform the calculations shown in Tables 17 through 19
are as follows: ; '•' > - ; ,' r • -...'•.;- -.:- : ;. : ;"(1.= -.,•.,•.•..'•:
t3~ 4- 5Ca2+ + OH~ -> Ca5OH(POtt)34- (1)
Mg2+ + 20H- .-*• Mg(OH)24- (2)
Ca2+ + C032~ •»• CaC03i (3)
CaC03 18Q°°F CaO + C02t (incineration) (4)
CaO + H20 -> Ca(OH)2 (5)
t- A13+ +'POt('3-. -> AlPO^^- . (6)
A13+ + 30H~ -> A1(OH)34- (7)
2Al(OH)o ^QQ01* A1203 + 3H20 (incineration) ' (8)
Fe3* + PO^3" ->- FeP04-l- (9)
Fe3+ + 30H~ -> Fe(OH)34- (10)
2Fe(OH)3 —n Fe203 + 3H20 (incineration) (11)
Z coagulant in = £ coagulant out (12)
Processabilitj
In every case where chemical treatment is used, there are waste chemical
sludges or mixtures of biological and chemical sludges requiring disposal.
Many methods of disposal however, involve dewatering the sludge prior to
final disposal. The.ease with which sludge may be dewatered should be a
consideration in chemical selection.
There may be some benefits in the dewatering and drying of biological
sludges containing alum. In tertiary treatment, alum and iron coagulants
generally produce gelatinous floe which is difficult and expensive to dewater,
On the other hand, lime coagulation produces a sludge which is much easier to
thicken and dewater. The quantity and nature of organics present in the
chemical sludge may alter significantly its dewatering characteristics..
For example, the presence of large quantities of activated sludge solids
may make the dewatering of lime sludges much more difficult than lime sludge,
alone.
Methods and equipment ordinarily used in handling and processing
biological sludges are generally applicable to chemical sludges or chemical-
biological sludge mixtures. Gravity or flotation thickening may be used,
and dewatering may be achieved by use of drying beds, lagoons, centrifuges,
vacuum filters, filter presses, or horizontal belt filters. The important
points to be considered, however, are:
39
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TABLE 17
Estimate of Lime Sludge Quantities
Raw sewage suspended solids
Raw sewage volatile suspended solids
Raw sewage PO43~
Raw sewage total hardness
Raw sewage Ca2+
Raw sewage Wig2"1"
Effluent PO4
Effluent Ca2+
Effluent Mg2+
250 mg/l
150 mg/l
11.5 mg/l asP
170.5 mg/l as CaCO3
60 mg/l
5 mg/l
0.3 mg/l as P
80 mg/l
0
Lime dosage
From equation 1
From equation 2
From equation 12
From equation 3
400 mg/l as Ca(OH)2 or
216 mg/l as Ca2+
Ca5OH(PO4)3 formed is 1 mole per 3 moles P
11.2
30.97
= 0.365 mole P removed
n ^RR
Therefore -^—• or0.122 mole Ca5OH(PO4)3 are formed; fw is 502
Therefore weight is 0.122X 502 = 61 mg/l as Ca5OH{PO4)3
Mg(OH)2 formed is 1 mole per mole Mg2+
5
Therefore 0.206 X 58.31 = 12 mg/l as Mg(OH)2
Ca2+ in = Ca2* out; Ca2+ in = 60 + 216 = 276
Ca2+ content of Ca5OH(PO4)3 formed = 5 X 40 X 0.122 = 24 mg/l
Ca2+ lost in effluent = 80 mg/l
Therefore Ca2"1" not accounted for = 276 - (80 + 24) = 172 mg/l
CaCO3 formed is 1 mole per mole Ca2+
172
Therefore -7^- = 4.3 moles CaC03; fw = 100
So weight of CaCO3 = 430 mg/l
Sludge composition
Sludge species
Raw sewage solids
Ca5OH(P04)3
Mg(OH)2
CaCO3
Total
Total weight
250 mg/l = 2,080 pounds per million gallons
61 mg/l = 510 pounds per million gallons
12 mg/l =100 pounds per million gallons
430 mg/l = 3,600 pounds per million gallons
6,290 pounds per million gallons
Ash
Pounds per million gallons
832
510
100
2,020
3,462
40
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Estimate of Alum Sludge Quantities
Raw sewage suspended solids
Raw sewage volatile suspended solids
Raw sewage PO43~
Raw sewage total hardness
Raw sewage Ca2+
Raw sewage Mg2+
Effluent P04
Effluent Ca2+
Effluent Mg2+
Effluent AI3+ :
250 mg/i
150mg/l
11.5mg/lasP
170.5 mg/l as CaCO3
60 mg/l
5 mg/l
0.3 mg/l as P
60 mg/l
5
0
Alum dosage
From equation 6
From equation 12
From equation 7
200 mg/l as AI2(SO4)3-14H2O - fw = 594
AIPO4 formed is 1 mole per mole of P
11.2
30.97
= 0.365 mole P removed
Therefore 0.365 mole of AIPO4 are formed; fw is 122
Therefore weight is 0.365 X 122 = 44 mg/l
AI3+ in = AI3+ out; AI3+ in = 18.1 mg/l
AI3+ content of AIPO4 = 0.365 X 27 = 9.9 mg/l
AI3+ not accounted for = 18.1 - 9.9 = 8.2 mg/l
AI(OH)3 formed is 1 mole per mole AI3+
Therefore || = 0.31 mole AI(OH)3; fw = 78
So weight of AI(OH)3 is 0.31 X 78 = 24 mg/l
Sludge composition
Sludge species
Raw sewage solids
AIPO4
AI(OH)3
Total
Total weight
250 mg/l = 2,080 pounds per million gallons
44 mg/l = 368 pounds per million gallons
24 mg/l = 200 pounds per million gallons
2,648 pounds per million gallons
Ash
Pounds per million gallons
832
368
133
1,333
41
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TABLE 19
Estimate of Iron Sludge Quantities
Raw sewage suspended solids
Raw sewage volatile suspended solids
Raw sewage P043~
Raw sewage total hardness
Raw sewage Ca2+
Raw sewage Mg2+
Effluent P04
Effluent Ca2+
Effluent Mg2+
Effluent Fe3+
250 mg/l
150mg/l
11.5 mg/l as P
170.5 mg/l as CaCO3
60 mg/l
5 mg/l
0.3 mg/l as P
60 mg/l
5
0
FeCI3 dosage
From equation 9
From equation 12
From equation 10
80 mg/l
FePO4 formed is 1 mole per mole P
' = 0.365 mole P removed
30,9 /
Therefore 0.365 mole of FePO4 are formed; fw= 151
Therefore weight is 0.365 X 151 = 55 mg/l
Fe3+ in = Fe3+ out; Fe3+ in = 28 mg/l
Fe3+ content of FePO4 = 0.365 X 55.8 = 20.4 mg/l
Fe3+ not accounted for = 28 - 20.4 = 7.6 mg/l
Fe(OH)3 formed is 1 mole per mole Fe3+
Therefore =^r = 0.136 mole Fe(OH),;fw= 107
bb.o °
So weight of Fe(OH)3 = 0.136 X 107 = 15 mg/l
Sludge composition
Sludge species
Raw sewage solids
FeP04
Fe(OH)3
Total
Total weight
250 mg/l = 2,080 pounds per million gallons
55 mg/l = 460 pounds per million gallons
15 mg/l =122 pounds per million gallons
2,662 pounds per million gallons
Ash
Pounds per million gallons
832
460
105
1,397
42
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._ .-.A-fs-V ---?
e Greater solids production results from chemical usage.
» Greater solids production will have an impact on sludge handling and/
conditioning unit processes.
. Operation and maintenance difficulties may be significantly different
with sludges containing large quantities of chemicals.
Finally, it is recommended that appropriate laboratory and pilot tests be
used in determining the most effective and economical methods of sludge
processing. , ,
Another consideration in chemical sludge handling is the possibility
of chemical recovery and reuse. For example, lime sludges can be recalcmed
and reused, but there is no method currently available for recovery and
reuse of iron salts. In cases where sodium aluminate is a good coagulant,
the alkaline method for alum recovery may be used If laboratory testing
shows sodium aluminate to be an unacceptable coagulant for the wastewater
under consideration, then the acid method for alum recovery may be used when
the treatment goal is suspended solids removal. On the other hand, the acxd
recovery "Shot is not applicable if one of the treatment goals is phosphorus
removal. - •
In many cases, sludge handling techniques may be too complex for the
operator alone to evaluate effectively. The services of a consulting
engineer would be most valuable in assessing the situation, recommending a
solution, and designing the necessary components of the system.
Sludge Disposal ^
Sludge disposal is perhaps the most important factor governing the
choice of chemicals. In locations where there are available large, remote
areas of land, almost any kind of sludge, wet or dry, stable or decomposing,
can be, and is, disposed of by hauling or pumping to these land disposal
sites. In many places, however, this method for sludge disposal probably
will not be allowed indefinitely and other alternatives will have to be
developed.
Alum and iron sludges usually can be added to anaerobic digesters. The
higher digester loadings resulting from additional sludge production usually
will not upset the operation unless an organic overloading condition exists.
Release of soluble phosphorus from the sludge during digestion is minimal.
Final disposal of the digested sludge can be on land, in a landfill, or by
dewatering and'incineration.
Alum, iron, and lime sludges can be disposed of directly onto land, but
at warm temperatures, alum and iron sludges may need lime treatment to
prevent d.dors.
43
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In large systems, sludge thickening or dewatering prior to lagooning
or incineration should be considered. Sludge incineration, particularly
for' large cities, has the advantage of converting organic solids to ash, thus
reducing the weight and volume of solids. Alum, iron and lime sludges can
be effectively incinerated.
The operator may find it useful to refer to EPA Technology Transfer
Manual, Process Design Manual for Sludge Treatment and Disposal, (Reference 9)
The manual presents a review of sludge processing techniques and procedures
for selecting optimum designs.
44
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i. t.i-i'kt- 31 --J
d.^ 3ac" f let;,?
SECTION 3
SELECTING CHEMICAtiS FOR USE
-------
-------
SECTION 3
SELECTING CHEMICALS FOR USE
There are many different chemicals which can be used in practically
every phase of wastewater treatment. As water quality and wastewater treatment
requirements continue to become more stringent, the role of chemicals in
improving or maximizing wastewater treatment plant performance becomes
increasingly important. Often there is more than one chemical that can be used
for a particular problem. In every case, there are advantages and disadvantages
associated with each chemical as well as other factors which will influence
the operator's choice of chemicals. .General factors to consider in selecting
chemicals include:
« Effectiveness
• Cost
« Reliability of supply
• Sludge considerations
• Compatibility with other treatment processes
« Environmental effects
There are a number of references available to the operator which provide
detailed information on chemical use in relation to the above factors.
Principal references include the following:
1. Operation of Wastewater Treatment Plants, Manual of Practice No. 11,
Water Pollution Control Federation, 1976.
The manual describes techniques of unit process operations, as
well as corrective measures regarding process problems. Improved
performance and physical-chemical treatment techniques are also
covered in the text.
2. Wastewater Treatment Plant Design, Manual of Practice No. 8, Water
Pollution Control Federation, 1977.
The manual contains a chapter specifically on chemical treatment,
including use in coagulation, phosphorus removal, and pH control.
Mixing and chemical feed systems also are discussed.
3. Field Manual for Performance Evaluation and Troubleshooting at Municipal
Wastewater Treatment Facilities, EPA-430/9-78-001, January 1978.
45
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This manual describes procedures for evaluating and troubleshooting
various unit processes commonly used at wastewater facilities. One
chapter is devoted to chemical feeding and conditioning, and other
chapters contain information on the use of chemicals in improving
process operations. Procedures for evaluating process efficiencies
also are included.
4. Process Design Manual for Phosphorus Removal, EPA 625/1-76-OOla,
April 1976.
Phosphorus removal methods that have been found effective and
practical are discussed in this manual. The methods include
chemical precipitation using aluminum and iron salts, and lime.
Practical points for chemical addition also are described and
documented by case histories.
5. Process Design Manual for Suspended Solids Removal, EPA 625/l-75-003a,
January 1975.
This manual describes specific processes and design considerations
for removal of suspended solids in municipal wastewater. Detailed
information also is provided concerning the handling and application
of coagulant chemicals.
6. Process Design Manual for Upgrading Existing Wastewater Treatment
Plants, EPA 625/l-71-004a, October 1974.
The capabilities, limitations and interrelationships of various unit
processes are examined in this manual with considerable emphasis on
the use of chemicals in upgrading treatment facilities<
7. Process Design Manual for Sludge Treatment and Disposal, EPA 625/1-79
-Oil, September 1979.
Emphasis is placed on operational considerations and interrelationships
of various sludge treatment processes including chemical conditioning
of sludges.
EFFECTIVENESS
One of the first considerations in the selection of chemicals is the
degree of effectiveness which can be expected from the chemical addition.
As an aid i'n predicting effectiveness, it is very helpful to obtain information
on experience and operating results from full-scale plants at other locations.
However, caution should be exercised in using such data from other plants;
the operator should not assume that a certain chemical used at one plant
will produce identical results at a different plant. The operation of many
treatment plants often is unique and chemicals chosen for use must be able
to handle these variations in performance and still produce an effluent of
uniform quality. The effectiveness of a particular chemical varies in
different applications and often depends on operating conditions.
46
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In order to have a better idea of the expected results of chemical
addition, laboratory and/or pilot tests using the proposed chemical should
be performed. The. objectives of laboratory studies usually are: (1) to
determine whether or not the wastewater or sludge may be successfully
treated by the proposed chemical, and (2) to obtain data for the design
and operation of pilot and full-scale facilities. After eliminating
alternative chemicals which do not produce satisfactory results on the
. ' •" . . v"».,, " •• i» \' -' i--^?«- -1: ,. . • f L -. T,, , , , , „ . - ,
basis of 'laboratory studies, aicost comparison should be performed to
select from the remaining chemicals. It should be recognized, however,
that laboratory and pilot tests do not always adequately evaluate sludge
problems orfproblems associated with recycled process streams -or return
solids. It!isronly at plant-scale that many of the real operational
problems become completely evident. ' "•
More detailed information on chemical effectiveness is provided in
Section 2 of this manual.
''
COST ^ ... :..:,-.-,;,-*,, -',.!.. - -'--.-. .-.- , -' '
Another factor in chemical selection is cost - both capital and oper-
ating. Capital costs for handling and feeding various chemicals can vary
considerably depending on the characteristics of the chemical to be fed,
the form (liquid, powder, gas) in which the chemical is purchased, and the
form in which the chemical ultimately is used in the treatment process.
Costs will be higher for chemicals which require special handling materials
for storage, feeding, piping and accessories, and sophisticated pacing and
control equipment. The appendix of this manual provides a ready reference
for information on each chemical, its available forms, cost, storage,
feeders, and acceptable handling materials. The costs quoted in the appen-
dix were obtained from the November 5, 1979 issue of the Chemical Marketing
Reporter. These costs are presented only for guidance and are subject to
significant variations due to local market conditions. Transportation is
a significant cost for some locations. Cost quotations for the chemicals
being considered should be obtained from the manufacturer or supplier
prior to final chemical selection.
The cost at point of origin usually is quoted by the manufacturer in
cents or dollars per pound, per 100 pounds, or per ton, and varies according
to the size of the order. It may be a price "f.o.b. cars" at the point of
manufacture or at a regional stock point. When small lots are purchased,
the f.o.b. point is important since the manufacturer ships to the regional
stock point in bulk at lower rates in order to give the customer the benefit
of this savings. The point of shipment origin should always be clearly stated
since transportation costs on low-priced materials may actually be in excess
of the cost of the material, especially if long hauls are involved. The
manufacturer should supply this information, if it is requested by the
customer.
Many manufacturers quote prices "f.o.b." from a distribution point but
also will give the customer information on the expected cost of transportation
47
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by rail or truck to the point of usage. Sometimes, manufacturers will
also quote "freight allowed," which means that they will assume the freight
charge on the shipment. In small shipments, it is important to compare
the cost of shipment by truck to the cost of shipment by rail. While the
truck rate may be higher than the rail rate, the material will be taken
from the manufacturer's plant and delivered to the door of the plant at no
extra cost. On the other hand, by rail, even though the price given is as
"f.o.b. your nearest freight station," there will be extra costs for
handling and hauling of the material from the freight station to the plant.
Therefore, the overall delivered cost may be less by truck. These factors
should be considered in determining chemical costs.
In comparing the economics of various chemicals, one must not only
consider the relative quantities of chemicals needed, but also the rela-
tive cost of handling the resulting sludges. For example, the cost per
pound of lime is typically lower than that of alum, but larger dosages of
lime generally are needed to achieve the same results as alum for waste-
water coagulation. Clearly, a complete cost analysis including all of the
system variables is necessary to determine which of the two chemicals is
most economical.
Table 20 shows an example of a typical cost evaluation for two differ-
ent chemical disinfection systems for a 5-mgd plant. The cost comparison
shows both capital and annual costs for disinfection using chlorine and
ozone. In this analysis the predominant factors responsible for the higher
cost of ozonation are the capital cost and energy usage. Unit costs
assumed in this analysis include labor at $9.00/hr, and energy at $0.03/kwh.
In other situations the cost analysis may show nearly equal capital costs
for several alternative chemicals. For example, in comparing various
coagulants, the capital costs may be very close, but operation and maintenance
costs may vary significantly depending on chemical dosages, unit chemical
costs, sludge effects, and chemical handling costs.
Cost considerations also should include the possibility of using a
single chemical for more than one purpose. For example, it may be more
economical to use a single chemical such as chlorine for odor control,
control of bulking sludge, and disinfection, rather than to use a different
chemical for each of the three operations. The possible cost savings for
such multiple usage can only be determined through a detailed cost analysis
of the various alternatives.
RELIABILITY OF SUPPLY
Reliability of supply is perhaps as important as effectiveness in
selecting chemicals. There is little advantage in selecting a chemical
which satisfies all the requirements in a treatment process if the chemical
is not readily available.
Regardless of the chemical used, there must be a sufficient supply on
hand at all times to cover the treatment plant needs for daily operation
48
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TABLE 20
..... Example Cost Comparison of
Disinfection Alternatives
. for a 5-mgd Plant
Capital Costs
Annual Costs
Labor
Energy
Maint. & Material
Amortized Capital
TOTAL ANNUAL
Chlprination
$235,000
12,000
2,000
27,000
21,970
$ 62,970
Ozonation
$510,000
8,200
56,000
7,800
47,680
$119,680
ASSUMPTIONS:
Chlorine dosage, 5 mg/1
Chlorine contact time, 30 minutes
Liquid chlorine cost, $250/ton
Ozone generation from air
Ozone dosage, 10 mg/1
Ozone contact time, 15 minutes
Amortization rate, 20 yrs @ 6-7/8%
49
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plus enough to cover the time between order placement and receipt of the
material. It is best to allow a reasonable factor of safety to overcome
delays in shipment or transportation, especially if the chemical is to be
transported long distances.
Another important consideration is the length of time a chemical
will retain its full potency. This factor has a definite effect on the
amount of chemical to be purchased and delivered at any one time. If the
manufacturer states that the raw material will retain its full potency six
months, then it would not be economical to purchase it in quantities which
would last much longer. If potency will last for a year, it may
be more economical to purchase the chemical in quantities sufficient to last
for that period. In most cases there is a differential in price for purchases
in large lots, particularly for higher priced items. But when large quan-
tities are ordered to last over long periods, adequate provision must be
made for proper storage facilities. Depending on the characteristics of
the selected chemical, the cost of such storage facilities may add
considerably to the overall cos£ of the item.
To avoid or minimize potential problems in obtaining chemicals,
suppliers of the specific chemical should be contacted for details on
chemical availability before the chemical is selected for use in the
treatment plant. The Appendix can be used to identify major manufacturers
and suppliers of various chemicals, and to provide information on typical
shipping containers and quantities.
It is also advisable to consider market trends for wastewater treatment
chemicals to anticipate possible chemical shortages or large cost increases.
The market for wastewater treatment chemicals has expanded during the last
decade and will probably continue to grow in future years. Both municipal-
ities and industries will continue to improve and expand their treatment
facilities to meet the more stringent effluent standards now in existence.
This will result in increasing demands for wastewater treatment chemicals.
SLUDGE CONSIDERATIONS
Selection of a treatment chemical and point of application should take
into account the relative sludge mass, and the ability to process and
dispose of the additional solids.
The increase in sludge production depends primarily on the chemical
used and the point at which it is applied in the treatment process. The
resulting sludge can be handled by several conventional methods, but
sludge characteristics such as dewatering and digestion characteristics
may change. Section 2 of this manual contains more detailed information
on sludge quantities, processability and disposal.
50
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COMPATIBILITY WITH OTHER TREATMENT PROCESSES
Another consideration in chemical selection is compatibility with other
processes used in the overall treatment scheme. The possible effects on
waste streams or recycled solids also are very important.
Due to variations in wastewater characteristics and treatment plant design
and operation, the choice of chemical and point of chemical addition will have
varying effects on other plant processes. These effects are best determined
in two steps: a laboratory feasibility study followed by pilot tests or by
full-scale plant tests, if possible. The laboratory study should provide a
preliminary evaluation of various chemicals to determine their general
effectiveness and estimated dosage. Pilot or full-scale plant tests then
should provide more detailed information on overall compatibility with other
plant processesr Additional guidance on chemical dosages is provided in
Section 2 of this manual.
ENVIRONMENTAL EFFECTS
As more stringent discharge requirements are initiated and enforced,
additional consideration should be given to choosing chemicals which will
be environmentally safe upon final disposal. For example, the most econo-
mical and widely accepted disinfectant for wastewaters is chlorine. How-
ever, because chlorine has been implicated in the formation of cancer-
causing substances, there may be situations where ozone becomes a preferred
disinfectant. But because of costs, high energy requirements, and the
fact that ozone provides no residual protection, the use of ozone normally
is not recommended unless unusual environmental concerns exist.
There are a number of other groups of chemicals in which selection
may be influenced by environmental effects. Table 21 provides examples
of such chemicals and the reasons why they may be considered environmentally
undesirable.
In order to minimize problems of this nature it is best to consult with
the appropriate local regulatory agency before making firm plans to use a
chemical which may have undesirable impacts on the environment.
LABOR REQUIREMENTS
In selecting chemicals and chemical feeders, consideration should be
given to labor requirements with respect to feeding and handling of chemicals
and equipment operation and maintenance. It is important to recognize that
labor associated with various chemicals depends not only on the particular
chemical, but also on the characteristics of the chemical and the form in
which it is purchased, stored, and fed. For example, less labor generally
will be required to use a chemical which is both purchased and fed in the
same form than a chemical which is purchased in dry form, dissolved for
51
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TABLE 21
Environmental Effects of Chemical Discharges
Chemical
Ammonia
Alum or
Iron salts
Chlorine
Chlorine
Potential Use
Control of pH or
alkalinity
Coagulation
Disinfection
Breakpoint
chlorination for
removal
Methanol
Carbon or food
source for bacteria
Environmental Effect
Upon discharge, high ammonia
concentrations can be toxic
to fish, deplete oxygen in
receiving waters and en-
courage algae growth.
Increases effluent TDS.
Increases sludge.
Increases effluent TDS,
high residuals can be
toxic to fish..
May produce acidic effect
on effluent, requiring
addition of another chemi-
cal for neutralization.
Increases chlorides in
effluent.
If overdosed, methanol
could be discharged in
plant effluent, resulting
in higher BOD.
52
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storage and later diluted for feeding. Table 22 illustrates the wide
variation in operation and maintenance labor for several commonly used
chemicals for sludge conditioning. These figures show typical labor require-
ments for unloading, storing and feeding operations. The primary components
which cause high labor requirements for unslaked lime are operation and
maintenance related to the slaking and feeding equipment. As Table 22
illustrates, there can be considerable difference in staffing requirements
for various chemicals, and these differences should be considered in
selecting chemicals.
53
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TABLE 22
Chemical Treatment Labor Requirements
Chemical
Ferric chloride
Lime (slaked)
Lime (unslaked)
Polymer (dry)
Polymer (liquid)
Capacity,
Ib/hr
10
50
100
500
100
500
1,000
100
.500
1,000
.5
1.0
5.0
10.0
.5
1.0
5.0
10,0
Operation & Maintenance
Labor, hr/yr
150
210
300
800
1,800
1,850
2,100
2,400
2,400
2,900
500
580
750
850
390
400
420
440
Labor for operation and maintenance of unloading, storing and
feeding facilities.
54
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SECTION 4
FEEDING AND HANDLING SYSTEMS
-------
-------
SECTION 4
FEEDING AND HANDLING SYSTEMS
Feeding systems are necessary for the controlled addition of chemicals
to wastewater, whether the chemicals are solid, liquid or gas. The design
of a chemical feed system must consider the form of each chemical desired
for feeding, the physical and chemical characteristics of the chemical,
maximum and minimum waste flows, and the reliability of the feeding devices.
The facilities for chemical feeding are relatively simple and consist of
equipment to store the chemical(s), feed the chemical(s) at controlled dosages,
place the chemical(s) in solution or slurry, arid feed the solution to the
process as shown in Figure 4.
SUPPLIER
TRANSPORT
STORAGE +-
CHEMICAL
MIXING
WITH
WATER
i SOLUTION !
~~M FED TO '
| PROCESS j
Figure 4. Chemical feeding system schematic.
In suspended and colloidal solids removal from wastewaters the chemicals
used are generally in liquid or solid form. Those in solid form are usually
converted to solution or slurry form prior to introduction to the wastewater
stream; however, some chemicals are fed in a dry form." In either case, some
type of solids feeder is usually required. This type of feeder has numerous
different forms due to wide ranges in chemical characteristics, feed rates,
and degree of accuracy required. Liquid feeding is somewhat more restrictive,
depending mainly on liquid volume and viscosity.
The capacity of a chemical feed system is important to consider in both
storage and feeding. Storage capacity design must take into account^the
advantage of quantity purchase versus the disadvantages of construction cost
and chemical deterioration with time. Potential delivery delays and chemical
use rates are important factors which must be considered. Storage tanks or
bins for solid chemicals must be designed with proper consideration of the
angle of repose of the chemical and its necessary environmental requirements,
such as temperature and humidity. Size and slope of feeding lines are
important along with their materials of construction, since some chemicals
are corrosive to certain materials.
55
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Chemical feeders must accommodate the minimum and maximum feeding rates
required. Manually controlled feeders have a common range of 10:1, but this
range can be increased to about 20:1 or 30:1 with dual control systems.
Chemical feeder control can be manual, automatically proportioned to flow,
dependent on some form of process feedback, or a combination of any two of
these. More sophisticated control systems are feasible if proper sensors
are available. If manual control systems are specified with the possibility
of future automation, the feeders selected should be able to be converted
with a minimum of expense. An example would be a feeder with an external
motor which could easily be replaced with a variable speed motor or drive
when automation is installed. Standby or backup units should be included
for each type of feeder used. Points of chemical addition and piping to
them should be capable of handling all possible changes in dosing patterns
in order to have proper flexibility of operation. Designed flexibility in
hoppers, tanks, chemical feeders and solution lines is the key to maximum
benefits at least cost.
Solids characteristics vary considerably and the selection of a feeder
must be made carefully, particularly in a smaller-sized facility where a
single feeder may be used for more than one chemical. In general, provisions
should be made to keep all dry chemicals cool and dry. Dryness is very
important, as hygroscopic (water- absorbing) chemicals may become lumpy,
viscous or even rock hard; other chemicals which absorb water less readily
may become sticky from moisture on the particulate surfaces, causing, increased
arching in hoppers. In either case, moisture will affect the density of the
chemical which may result in under-feed. Also, the effectiveness of dry
chemicals, particularly polymers, may be reduced. Dust removal equipment
should be used at shoveling locations, bucket elevators, hoppers, and feeders
for neatness, corrosion prevention and safety reasons. Collected chemical
dust may often be used along with stored chemicals. In general, only limited
quantities of chemical solutions should be made from dry chemicals, since the
shelf life of mixed chemicals (especially polymers) may be short.
DRY CHEMICAL FEEDERS
The simplest method of feeding dry or solid chemicals is by hand. Solid
chemicals may be preweighed and added or poured by the bagful into a dissolving
tank. This method is generally limited to very small operations, however,
and dry chemical feed equipment is usually required.
A dry feed installation (Figure 5) consists basically of a storage bin
and/or hopper, a feeder, and a dissolver tank. Dry feeders are either of the
volumetric or gravimetric type. Volumetric feeders usually are used only
where low initial cost and low feed rates are required. These feeders
deliver a constant, preset amount of chemical and do not recognize changes in
material density. This type of feeder must be calibrated by trial and error
at the outset, and then readjusted periodically if the material changes in
density.
Most types of volumetric feeders generally fall into the positive
displacement category. All designs of this type use some form of moving
56
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_DUST COLLECTOR
X2-FILL PIPE (PNEUMATIC)
BULK STORAGE
BIN
DAY HOPPER
FOR DRY CHEMICAL
FROM BAGS OR DRUMS^
.BIN.GATE
-FLEXIBLE
COKHECTION
ALTERNATE SUPPLIES DEPENDING
ON STORAGE
DUST COLLECTOR
XBAG FILL
-SCREEN
WITH BREAKER
DUST AND VAPOR REMOVER
WATER
SUPPLY
FEEDER
SCALE OR SAMPLE CHUTE
DRAIN
SOLENOID VALVE'
CONTROL
VALVE -^ROTAMETER
PRESSURE REDUCING
VALVE
WATER SUPPLY
-MIXER
/
-/
DISSOLVER
/,
r
L
^-BAFFLE
.LEVEL
1
HOLDING
TANK
PROBES
c
GRAVITY TO
APPLICATION
_ PUMP
TO APPLICATION
Figure 5. Typical dry feed system.
57
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cavity of a specific or variable size. In operation, the chemical falls by
gravity into the cavity and is almost fully enclosed and separated from the
hopper's feed. The rate at which the cavity moves and is discharged, together
with the cavity size, govern the amount of chemical fed. Positive displacement
feeders often use air injection to enhance flowability of the material.
Rotary Paddle Feeder
An example of a positive displacement rotary feeder is illustrated in
Figure 6. This rotary paddle feeder is especially effective for fine materials
that tend to flood. The paddle or vane is located beneath the hopper discharge,
with the feed being varied by means of a sliding gate and/or variable speed
drive. The feed rate can be varied easily by adjusting the variable speed
drive on the vane shaft. A variant of the rotary paddle feeder is the pocket
feeder, also called the star or revolving door feeder, in which the paddle
is tightly housed to permit delivery against vacuum or pressure.
Oscillating Hopper Feeder
Another type of volumetric feeder is the oscillating hopper, or oscillating
throat feeder. This feeder (Figure 7) consists of a main hopper and an
oscillating hopper which swivels on the end of the main hopper. The material
completely fills both hoppers and rests on the tray beneath. As the oscillating
hopper moves back and forth, the scraper, which rests on the fixed tray below,
is moved first to the left and then to the right. As it moves, it pushes a
ribbon-like layer of dry chemical off the tray. The capacity is fixed by the
length of the stroke, which may be varied by means of a micrometer screw.
Further adjustment is possible by changing the clearance between the hopper
and the fixed tray, which may be raised or lowered. This type of feeder is
one of the most widely used in small water and wastewater plants.
Oscillating Plate Feeder
In the oscillating plate feeder a plate is mounted below the bottom
spout in the storage hopper so that the chemical spills out onto the plate
as it comes out of the storage hopper. A leveling bar is mounted above the
plate on each of the two ends. The plate is mechanically linked to the
drive motor so that the plate slowly oscillates from side to side as the
feeder operates. The magnitude of oscillation can be adjusted with the
mechanical linkage. This provides a dosage adjustment. Each time the plate
oscillates from one side to the other a measured amount of chemical drops
off the plate into the solution, tank. The rake bar above each end of the
plate helps to regulate the repeatability of the feed rate.
Grooved Disc Feeder
This feeder consists of a grooved horizontal disc which meters the
chemical addition. The disc rotates and the grooves are filled as they pass
under the storage hopper, are struck off level, and then a stationary plow
removes the material from the groove for metering. The feed rate is varied
by changing the speed of disc rotation or by changing the groove size. Typically,
these feeders are used for applications requiring small feed rates of dry materials.
58
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PRESSURE
PLATE
ROTOR
SCRAPER
VARIABLE SPEED
TRANSMISSION
MOTOR
INSPECTION AND
SAMPLING. CHUTE
Figure 6. Positive displacement rotary feeder.
59
-------
OSCILLATING HOPPER
SCRAPER
Figure 7. Oscillating hopper or universal volumetric feeder.
60
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Vibrating Feeder
The vibrating feeder is another volumetric feeder. With this feeder,
motion is obtained by means of an electromagnet anchored to the feeding
trough, which in turn is mounted on flexible leaf springs. The magnet, x
energized by pulsating current, pulls the trough sharply down and back -
then the leaf- springs return it up and forward to its original position.
This action is repeated 3600 times per minute (when operating on 60-cycle,
a.c.), producing a smooth, steady flow of material.
Volumetric Belt Feeder
The volumetric belt feeder uses a continuous belt of specific width
moving from under the hopper to the dissolving tank. The material falls on
the feed belt from the hopper and passes beneath a vertical gate. For a
given belt speed, the position of the gate determines the volume of material
passing through the feeder. An example of a volumetric belt-type feeder is
shown in Figure 8. .,
Screw-Type Feeder .
The volumetric screw-type feeder employs a screw or helix at the
bottom of the hopper to transfer dry chemical to the solution chamber.
A typical screw-type volumetric feeder is'shown in Figure 9.
The basic drawback of the volumetric feeder is that it cannot compensate
for changes in the density of materials and is therefore not as accurate
as two other types of dry feeders: the gravimetric and loss-in-weight
feeders. For these feeders, the volumetric design is modified to include
a gravimetric or loss-in-weight controller, which allows for weighing of
the material as it is fed. "Both gravimetric and volumetric feeders can be
used to feed in proportion to the flow of wastewater.
Belt-Type Gravimetric Feeder
Belt-type gravimetric feeders have a wide capacity range and usually can
be sized for any use in a wastewater treatment plant. Belt-type gravimetric
feeders use a basic belt feeder with a weighing and control system. Feed
rates can be changed by adjusting the weight per foot of belt, the belt
speed, or both. There are two types of gravimetric belt-type feeders, the
pivoted belt type and the rigid belt type.
The pivoted belt feeder consists of a feed hopper, an endless traveling
belt mounted on a pivoted frame, an .adjustable weight which counterbalances
the load on the belt, and a means of continuously and automatically adjusting
the feed of material to the belt. Dry chemical flow to the feeder can be
controlled by a gate placed between the feed hopper and the belt (as shown
in Figure 10) or by controlling the amplitude of vibration in a vibrating
deck placed between the feed hopper and the belt.
61
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FEED SECTION
GATE
STATIONARY DECK
J
FEED BELT
Figure 8. Volumetric belt type feeder
62
-------
MOTOR
GEAR REDUCER
FEED RATE REGISTER AND
FEED ADJUSTING KNOB
SOLUTION CHAMBER
HOPPER
ROTATING AND
RECIPROCATING
FEED SCREW
JET MIXER
Figure 9. Typical helix or screw-type volumetric feeder (courtesy of
Wallace & Tiernan, division of Pennwalt Corporation).
63
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HOPPER
COUNTERWEIGHT
FULCRUM
GATE
ENDLESS BELT
Figure 10, Pivoted belt gravimetric feeder.
64
-------
The rigid belt feeder is similar to the pivoted belt feeder except for
one main difference. With the pivoted belt filter, adjustment is accomplished
through action of the belt tilting up and down, while with the rigid belt,
adiusting occurs through action of the scale beam dependent only on the
weight of the belt. An example of a rigid belt gravimetric feeder is given
in Figure 11 •
Good housekeeping and the need for accurate feed rates dictate that the
gravimetric feeder be shut down and thoroughly cleaned on a regular basis.
Chemical build-up can affect accuracy and can even jam the equipment in
some cases.
Loss-In-Weight Feeder
The loss-in-weight feeder should be used where the greatest-accuracy or
more economical use of chemical is important. This feeder only works for feed
rates up to a rate of 4,000 Ib/hour. The loss-in-weight feeder lias a
material hopper and feeder set on enclosed scales. The feed rate controller
is used to deliver the dry chemical at the desired rate.
Dissolvers
Dissolvers are also important to dry feed systems since any metered
chemical must be wetted and mixed with water to provide a chemical solution
free of lumps and undissolved particles. Most feeders, regardless of type,
discharge their material to a small dissolving tank which is equipped with
a nozzle system and/or mechanical agitator depending on the solubility of
the chemical being fed. It is important that the surface of each particle
become completely wetted before entering the feed tank to ensure accurate
dispersal and to avoid clumping, settling or floating.
A dissolver for a dry chemical feeder is unlike a chemical feeder, which
by simple adjustment and change of speed can vary its output tenfold. The
dissolver must be designed for the job to be done., A dissolver suitable
for a rate of 10 Ib/hour may :not be suitable for dissolving at a rate of
100 Ib/hour.
The capacity of a dissolver is based on detention time, which is directly
related to the wettability or rate of solution of the chemical. Therefore,
the dissolver must be large enough to provide the necessary detention for
both the chemical and the water at the maximum rate of feed.
SOLUTION FEEDERS
A typical solution feed system (Figure 12) consists of a storage tank,
transfer pump, day tank (for dilution), and liquid feeder. Some liquid
chemicals can be fed directly without dilution and the day tank would not
be needed. Dilution water is usually still added to the solution feed pump
discharge line after the chemical is metered to prevent plugging, reduce
delivery time, and to help mix the chemical with the water being treated.
65
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SCALE BEAM HOPPER
CONTROL WEDGE
^—•
O
VIBRATOR' *
VARISPEED TRANSMISSION ENDLESS BELT
Figure 11. Rigid belt gravimetric feeder.
66
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TRUCK FILL LINE
DILUTION
WATER
SOLUTION
STORAGE TANK
•VENT, OVERFLOW
AND DRAIN
DILUTION WATER
TRANSFER
PUMP
VENT, OVERFLOW
AND DRAIN
•MIXER
SAMPLE TAP
SOLUTION
FEEDER
POINT OF
APPLICATION
Figure 12. Typical solution feed system.
67
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Liquid feed systems are generally recommended for use:
• When low chemical quantities are required.
• With less stable chemicals.
• With chemicals which are fed more easily as a liquid,
• Where handling of dusty chemicals or dangerous chemicals
is undesirable.
• With materials only available as liquids.
Liquid feeders usually are metering pumps or orifices. These metering pumps
usually are of the positive displacement variety, plunger or diaphragm type.
Examples of plunger and diaphragm pumps are given in Figure 13. Positive
displacement pumps can be set to feed over a wide range by adjusting the pump
stroke length. In some cases, control valves and rotameters may be all that
is needed, while in other cases the rotating dipper type feeder may be
satisfactory. For uses like lime slurry feeding, however, centrifugal pumps
with open impellers are used. The type of liquid feeder used depends on the
viscosity, corrosivity, solubility, suction and discharge heads, and internal
pressure relief requirements.
GAS FEEDERS
Gas feeders can be classifed as solution feed or direct feed. Solution
feed vacuum type feeders are most commonly used in chlorination and in
dechlorination with sulfur dioxide. In chlorination, chlorine gas is
metered under vacuum and is mixed with water or plant effluent in an injector
to produce a chlorine solution. The flow of chlorine gas is automatically
shut off on loss of vacuum, stoppage of the solution discharge line, or
loss of operating water pressure.
Direct feed or "dry feed" equipment is infrequently used, only when
either water or electricity or both is unavailable at a site. This type of
equipment is nearly the same as the solution feed type except that there is
no device for making and injecting an aqueous solution. The gas itself is
piped directly into the water to be treated.
More information about the uses and limitations of the general type of
chemical feeders is given in Table 23.
FEED SYSTEM REQUIREMENTS FOR SPECIFIC CHEMICALS
Alum
To prepare dry alum for feeding, dissolving tanks should be made of a
non-corrosive material. Dissolvers should be the right size to get the
desired solution strength. Most solution strengths are 0.5 Ib of alum to
1 gallon of water, or a 6% solution. The dissolving tank should be designed
68
-------
SUCTION VALVE
DIAPHRAGM PUMP
Figure 13. Positive displacement pumps.
69
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TABLE 23
Types of Chemical Feeders
Limitations
Type of Feeder
Dry feeder:
Volumetric:
Oscillating throat (universal)
Rotating cylinder (star) ....
Belt
Gravimetric:
Continuous— belt and scale
Loss in weight
Solution feeder:
Nonpositive displacement:
Decanter (lowering pipe) . . .
Orifice
Rotameter (calibrated valve)
Loss in weight (tank with
control valve).
Positive displacement:
Rotating dipper
Proportioning pump:
Piston
Gas feeders:
Solution feed
Direct feed
Use
Any material, granules or
powder.
Any material, any particle
size.
Most materials including NaF,
granules or powder.
Any material, granules or
powder.
Dry, free flowing material,
powder 'or granular.
Dry, free flowing material,
powder, granular, or lumps.
Dry free flowing material up
to 1%-inch size, powder or
granular.
Dry, free flowing, granular
material, or flood able
material.
Most materials, powder,
granular or lumps.
Most solutions or light slurries
Most solutions .
Gear solutions
Most solutions '.
Most solutions or slurries ....
Most solutions. Special unit
for 5% slurries.1
Most solutions, light slurries
Chlorine
Sulfur dioxide
Carbon dioxide »
Chlorine ...
Ammonia
Carbon dioxide
General
Use disc un-
loader for
arching.
Use hopper
agitator to
maintain
. constant
density.
.
Capacity
cu ft/hr
001 to 35
0.02 to 100 .; . . .
001 to 1 0
8 to 2 000
or
7.2 to 300
0 OS to 18
0002 toO 16
0 1 to 3 000
0.02 to 2
0 02 to 80
0.01 to 10 ... .
016 to 5
0005 toO 16
or
0.01 to 20
0 002 to 0 20
0 1 to 30
0 004 to 0 1 5
001 to 170
' 8000 Ib/day max
2000 Ib/day max
7600 Ib/day max
6000 Ib/day max
1 20 Ib/day max
1 0.000 Ib/dav max
Range
40 to 1
40 to 1
20 to 1
10 to 1
or
100 to 1
20 to 1
10 to 1
10 to 1
or
100 to 1
100 to 1
100 to 1
100 to 1
10 to 1
10 to 1
30 to 1
100 to 1
10 to 1
10 to 1
20 to
20 to
20 to
20 to
10 to
7 to
20 to
1 Use special heads and valves for slurries.
70
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for a minimum detention time of 5 minutes at the maximum feed rate.
Dissolvers should have water meters and mixers so that the water/alum
mixture can be. controlled. Most liquid alum is fed as it is delivered,
in a standard 50 percent solution.
Alum is usually fed by positive displacement metering pumps. Dilution
water usually is added to an alum feed pump discharge line to prevent line
plugging, to reduce delivery time to the point of application, and to.help
mix the alum with the water being treated. The output of the pumps can be
controlled automatically in proportion to plant flow. This is done by
setting the alum dosage for the maximum flow rate. The controls are then
set to automatically Adjust the off-on cycle and the amount of alum pumped
to the actual flow.
Carbon Dioxide
Feeding systems for the stack gas source of carbon dioxide consist of
simple valving arrangements, for admitting varying quantities of make-up air
to the suction side of the constant volume compressors, or-for venting excess
gas on the compressor discharge.
Pressure generators and submerged burners are regulated by valving
arrangements on the fuel and air supply. Generation of carbon dioxide by
combustion is usually difficult to control, requires frequent operator
attention and demands considerable maintenance over the life of the equipment,
when compared to liquid C02 systems.
^Commercial liquid carbon dioxide is more generally used because of its
high purity, the simplicity and range of feeding equipment, ease of control,
and smaller, less expensive piping systems. After vaporization, carbon
dioxide with suitable metering and pressure reduction may be fed directly
to the point of application as a gas. Metering of directly fed pressurized
gas is difficult due to the high adiabatic expansion characteristics of the gas.
Also, direct feed requires extremely fine bubbles to insure that the gas goes
into solution; this, in turn, can lead to scaling problems. Because of this,
vacuum operated, solution type gas feeders are preferred. Such feeders
generally include safety devices and operating controls in a compact panel
housing, with materials of construction suitable for carbon dioxide service.
Absorption of .carbon dioxide in the injector water supply approaches 100%
when a ratio of 1.0 Ib of gas to 60 gallons of water is maintained.
Chlorine
Elemental chlorine is a poisonous yellow-green gas at ordinary temperature
and pressure. The/gas is stored as a moisture-free liquid under pressure in
specially constructed steel containers from which it is vaporized either
directly or with heated vaporizers. Chlorine gas feeders may be classified
into two types, direct feed or solution feed.
Direct;feed or dry feed gas feeders deliver chlorine gas under pressure
directly to the point of application. Direct feed gas chlorinators are less
71
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safe than solution feed chlorinators and are used when there is no adequate
water supply available for ejector operation. In solution feed vacuum type
feeders, chlorine gas is maintained under a vacuum throughout the apparatus.
Vacuum is created by water flow through an injector to move the chlorine
from the supply system through the chlorine gas metering devices to the
injector. Chlorine gas is mixed with water in the injector and the chlorine
solution is moved to the point of application. In this feeder, the vacuum
controls the operation of the chlorine inlet valve such that the chlorine
will not feed unless sufficient vacuum is induced through the apparatus.
This type of feeder is most common because safe operation is assured. It
employs a direct indicating meter, and the flow of chlorine is automatically
shut off on•loss of vacuum, stoppage of discharge line, or loss of operating
water pressure.
In some cases it may be necessary to provide more than one point of
injection from a single injector, and this requires manifolding. Valves
for manifolding generally are either the ball type or diaphragm type.
There are two basic types of chlorine diffusers: one for discharging
chlorine solution into a pipe flowing full; and the other for discharging
into an open channel or open body of water.
A full discussion of chlorination is beyond the scope of this manual.
More information concerning chlorination systems is available in
References 3, 9 and 10.
Chlorine Dioxide
Chlorine dioxide is an intense greenish-yellow gas that is quite
unstable, and, under certain conditions, is explosive. It cannot be shipped
in containers as is chlorine gas because of its explosive nature, and it must
be generated at the point of use and applied immediately.
Although readily soluble in water, it does not react with water as does
chlorine. Chlorine dioxide is easily expelled from solution in water by
blowing a small amount of air through the solution. Aqueous solutions of
C1C-2 are also subject to some photodecomposition.
Chlorine dioxide is generated by oxidizing sodium chlorite with chlorine
(either chlorine gas or hypochlorite) at a pH of 4 or less. This means
that the injector system of the chlorination assembly must be such that the
chlorine solution strength is never less than about 500 mg/1. Since the upper
limit of this solution strength should not exceed 3,500 mg/1 to prevent
break-out of molecular chlorine at the point of application, the effective
range of chlorine dioxide production is about 7:1. Chemical feed devices can
handle ranges up to 20:1 on a flow proportional basis and 200:1 on a compound
loop control system.
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Ferric Chloride
Since ferric chloride is always fed as a liquid, it is normally obtained
in liquid form containing 20 to 45 percent FeCl3. When iron salts such as
ferric chloride are used for wastewater coagulation in soft waters, a small
amount of base (such as sodium hydroxide or lime) is needed to neutralize the
acidity of these strong acid salts.
ft '
Because of hydrolysis, it may not be a good idea to dilute ferric
chloride solution from its shipping concentration to a weaker feed solution.
Ferric chloride solutions may be transferred from underground storage to day
tanks with rubber-lined self-priming centrifugal pumps having teflon rotary
and stationary seals. Because liquid ferric chloride can stain or deposit,
glass-tube rotameters are not used for metering. Instead, rotodip feeders
and diaphragm metering pumps made of rubber-lined steel and plastic often
are used for feeding ferric chloride.
Ferric Sulfate
Feed solutions are usually made up at a water~to^chemical ratio of 2:1
to 8:1 (on a weight basis) with the usual ratio being 4:1 with a 20-minute
detention time. Care must be taken not to dilute ferric sulfate solutions
'to less than 1 percent in order to prevent hydrolysis and deposition.of ferric
hydroxide. •
Dry feeding requirements are similar to those for dry alum except that
belt type feeders are rarely used because of their open type of construction.
Closed construction, as found in the volumetric and loss-in-weight type
feeders, generally exposes a minimum of operating components to the vapor,
and thereby minimizes maintenance. A water jet vapor remover should be
provided at the dissolver to protect both the machinery and operator.
Ferrous Sulfate •
The granular form of ferrous sulfate has the best feeding characteristics
and gravimetric or volumetric feeding equipment may be used. The optimum
chemical-to-^water ratio for continuous dissolving is 0.5 Ib/gallon or 6"percent
with a detention time of 5 minutes in the dissolvers. Mechanical agitation
should be provided in the dissolver to assure complete solution.
1 ' •
Lime •
Although lime comes in many forms, quicklime and hydrated lime are used
most often for wastewater coagulation. Quicklime is almost all calcium oxide
(70 to 96 percent CaO). High-calcium quicklime contains more than 88 percent
CaO and less than 5 percent magnesium oxide (MgO) and is generally preferred,
for wastewater treatment. Dolomitic lime may contain up to 40 percent MgO,
which is not desirable for wastewater coagulation and which adversely affects
sludge thickening and dewatering.
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Quicklime (unslaked lime) is almost all CaO and first must be converted
to the hydrated form (Ca(OH)2)« Hydrated or slaked lime is a powder obtained
by adding enough water to quicklime to satisfy its affinity for water.
Hydrated lime needs only enough water to form milk of lime. Wetting or
dissolving tanks usually are designed for 5 minutes detention with 0.5 lb/
gallon of water or 6 percent slurry at the highest feed rate. Hydrated lime
often is useTd where maximum feed rates are less than 250 Ib/hour.
Dilution is not too important in lime fee'ding; therefore, it is not
necessary to control the amount of water used in feeding. Hydraulic jets
may be used for mixing in the wetting chamber of the feeder, but the jets
should be the right size for the water supply pressure.
Lime is never fed as a solution because of its low solubility in water.
Also, quicklime and hydrated lime usually are not applied dry directly to
the wastewater for the following reasons:
• they are transported more easily as a slurry;
• a lime slurry mixes better'with the wastewater than dry lime;
• pre-wetting the lime in the feeder with rapid mixing helps to make
sure that all particles are wet and that none settles out in the
treatment basin.
Major components of a lime feed system (illustrated in Figure 14) include
a storage bin, dry lime feeder, lime slaker, slurry holding tank, and lime
slurry feeder. The slurry holding tank is usually needed only when the point
of application is at a remote location. Quicklime feeders usually must be the
belt or loss-in-weight gravimetric types because bulk density changes so much.
Feed equipment usually has an adjustable feed range of at least 20:1 to
match the operating range of the slaker. The main parts of a lime slaker for
wastewater treatment usually include one or more slaking bins, a dilution
bin, a grit separation bin, and a continuous grit remover.
There are two basic types of lime slakers, the "paste" or "pug mill"
type slaker and the "detention" type slaker. The paste-type slaker (Figure 15)
admits water as required to maintain a desired mixing viscosity. The viscosity
therefore sets the operating retention time of the slaker. The detention-type
slaker (Figure 16) admits water to maintain a desired ratio with the lime, and
therefore the retention time is set by the lime feed rate. The detention
slaker produces a lime slurry of about 10 percent Ca(OH)2 while the paste
type produces a paste of about 36 percent. Other differences between the
two slakers are that the detention type slaker operates with a higher water
to lime ratio, a lower temperature, and a longer retention time. For either
slaker type, vapor removers are required for feeder protection, since lime
slaking produces heat in hydrating the CaO to Ca(OH)2-
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LIME
STORAGE
BIN
GATE
FLOW RECORDER
WITH PACING
TRANSMITTER
pH RECORDER
CONTROLLER
FLEXIBLE
\CONNECTOfy
QUICKLIME
FEEDER
_
U
1
LIMESLAKER
L
Solenoid valve —^j ' \
Slaking water.—. '—r^
Rotameters
• Dilution water
I Dosage I
| adjuster -p L.
J
Mixer
Variable speed*
meter —
Level
control?
LIME
SLURRY
FEEDER
pump
I ^s- Flow-transmitter
X
DH Sensor
Jl
i
Prlmary
Device
Treated
waste
Figure 14. Illustrative lime feed system for wastewater coagulation.
75
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SLAKING
WATER
TORQUE CONTROLLED
WATER -VALVE
DUST SHIELD
WATER SPRAY
SLAKING COMPARTMENT
SLURRY DISCHARGE
SECTION
GRIT DISCHARGE
LIQUID LEVEL
WATER FOR GRIT
WASHING
GRIT ELEVATOR
CLASSIFIER
Figure 15. Typical paste-type slaker.
76
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QUICKLIME
MIXER
GRIT DISCHARGE
MILK
OF LIME
OUTLET
GRIT WASH JETS
GRIT CONVEYER
Figure 16. Typical detention-type slake.r.
77
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The required slaking time varies with the source of lime. Fast slaking
limes will complete the reaction in 3 to 5 minutes, but poor quality limes
may require up to 60 minutes and an external source of heat, such as hot
water or steam. Before selecting a slaker, it is advisable to determine
the slaking time, best initial water temperature, and optimum water:lime
ratio for the lime to be used, according to procedures for slaking tests
recommended by the American Water Works Association. More information about
lime storage, handling, and use can be found in Reference 8.
Methanol
Methanol is a colorless liquid, and non-corrosive (except to aluminum
and lead) at normal atmospheric temperature. Transfer pumps should always
have positive suction pressure and should be protected by a strainer.
There are three basic pumping arrangements which can be.used: (1) diaphragm
chemical feed pumps using an adjustable stroke for volume control;
(2) positive displacement pumps with variable speed drives controlled by
either a flow meter or by counting Yevolutions; (3) centrifugal or regenera-
tive turbine pumps with variable speed drives controlled by a flow meter.
Ozone
Ozone is produced commercially by the reaction of an oxygen-containing
feed gas in an electrical discharge. The feed gas, which may be air, pure
oxygen, or oxygen enriched air, is passed between electrodes separated by
an insulating material. A high voltage of up to 20,000 V is applied to
the high tension electrode. The ozone molecule, made up of three oxygen
atoms, is highly unstable, and is one of the most powerful oxidizing
agents known.
Ozone is a pale blue gas having a distinct pungent odor. In concentra-
tions usually employed, the odor is detectable but the color is not visible.
It is both toxic and corrosive. Because of its unstable nature, it must be
generated at the point of use. Consequently, safety aspects of transporta-
tion and storage are eliminated.
There are three basic ways to generate and use ozone in wastewater
treatment: (1) generation from air, (2) generation from oxygen and recycle
oxygen to the ozone generation system, and (3) generation from oxygen used
for oxygen activated sludge system and recycle oxygen to the activated
sludge system. Figure 17 shows these different methods.
The once-through air approach uses conventional air drying techniques
such as compression and refrigeration, followed by desiccant drying. Ozone
generated from air is usually 0.5 to 2.0 percent by weight, but is usually
produced at 1.0 weight percent. Ozone is typically mixed with wastewater
in a contact basin as shown in Figure 18. Fine bubble diffusers are used
to feed the ozone into the basin. Packed beds have also been used as
contactors. Following treatment in the covered ozone contactor, the gas
is decomposed to prevent high concentrations of ozone from being released
to the atmosphere.
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ONCE-THROUGH AIR PROCESS
AIR
CHILLED
WATER
CLEAN AIR
DISCHARGE
WASTEWATER
COMPRESSOR
WATER
^
CONTACTOR
1
1
OZONE
DECOMP '
DEVICE
DRYER
TREATED
WATER
OXYGEN RECYCLE PROCESS
*«•••*••••••»•*•*
ONCE-THROUGH OXYGEN PROCESS
r
i
i
L.
COMPRESSOR
OZONE
GENERATOR
OZONE DECOMPOSITION
DEVICE
WATER
HAIhR
SLUOIit
REACTOR
EFFLUENT
WASTE
| WATER
1
OZONE
CONTACTOR
!_ET~j'
L
Figure 17. Alternative ozonation systems.
79
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To ozone
destruct
Influent
6
Upward velocity
£ 0.5 fps
X X
Entrance
baffle
TTTTT
/
TTTTTTTTTT
t
ILL
/
r
Downward
velocity
< 0.5 fps
Exit baffle
Figure 18. Typical ozone contact basin using porous diffusers,
80
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The oxygen recycle approach may be used to recover valuable oxygen-rich
off-gas from the contactor when very pure oxygen is fed to the ozone
generator. High-purity oxygen gas sometimes is used since it enables the
generator to produce two to three times as much ozone per unit time, and uses
only about half as much generator power per pound compared to ozone produced
from air.
Once-through oxygen is the simplest method of ozone wastewater disin-
fection. Dry oxygen is produced on-site by a cryogenic air separation process
or by pressure-swing adsorption and then fed to the ozone generator.
Wastewater is next treated by ozonation in the contactor and, after
4estruction of the unreacted ozone, the off-gas is used elsewhere in the
plant. It may, for example, be used in a biological reactor or fed into
incinerators for sludge disposal.
There are three basic types of commercially available ozone generators:
the Otto plate, the tube and the Lowther plate. More information about the
types of ozone generators available can be found in References 1 and 11.
Polymers
When dry polymers are used, the polymer and water must be'blended and
mixed to obtain the desired solution. Initially, complete wetting of the
polymer is necessary using a funnel-type aspirator. After wetting, warm
water must be added and gently mixed for about 1 hour. Polymer feed solution
strengths are usually in the range of 0.1 to 0.75 percent. Stronger solutions
.are often too viscous to feed. Metered solution is usually diluted just prior
to injection to the process to obtain better dispersion at the point of
application.
The solution preparation system can include either a manual or an
automatic blending system with the polymer dispensed by hand or by a dry
feeder to a wetting jet and then to a mixing-aging tank at a controlled
rate. The aged polymer solution is transported to a holding tank where
metering pumps or rotodip feeders feed the polymer to the process. A
schematic of a manual dry polymer feed system is shown in .Figure 19.
The solution preparation system may be an automatic batching system,
as shown in Figure 20, that fills the holding tank with aged polymer as
required by level probes. Such a system is usually provided only at large
plants.
Polymer solutions above 1 percent in strength should normally not be
used because they are very viscous and difficult to handle. Most powdered
polymers are very stable when dry, but even in cool, dry conditions, they
should not be stored as powders in unopened bags for more than 1 year.
Once polymers are dissolved, they may become, unstable within 2 or 3 days.
Liquid polymers need no aging and simple dilution is the only requirement
for feeding. The dosage of.liquid polymers may be accurately controlled
by metering pumps or rotodip feeders.
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WATER SUPPLY-
r-N-
POINT OF
APPLICATION
FEEDER
DISPERSER
MIXER
DISSOLVING-AGING
TANK
-HOLDING TANK
-SOLUTION FEEDER
Figure 19. Manual dry polymer feed system.
82
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tor.
WATER
SOLENOID ,SCALE
/ VACVE /
DISPERSER
BLENDER
KOTE: CONTROL t INSTRUMENTATION
WIRING IS NOT SHOWt
POINT OF APPLICATION
*
SOLUTI ON
FEEDERS.^^^
ION *f \ \
1
i T
1
HOLDING TANK
K-
TRANSFER PUMP
LEVEL PROBE
Figure 20. Automatic dry polymer feed system.
83
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Because polymers can cause very slippery conditions in a treatment
plant, spills should be cleaned up immediately. Other safety precautions
as specified by the manufacturer should also be observed.
Powdered Carbon
When powdered activated carbon is used, it is mixed directly with the
wastewater, fed as slurry, and removed by coagulation and settling. The
carbon slurry is transported by pumping the mixture at a high velocity to
keep the particles from settling and collecting along the bottom of the pipe.
The velocity of the slurry should be kept between 3 and 5 ft/second. At
velocities less than 3 ft/second, carbon will settle out in the pipeline;
and at velocities greater than 10 ft/second, excessive carbon abrasion and
pipe erosion will occur. At most plants, carbon slurries are fed at a
concentration around 10.7 percent or 1 Ib carbon/gallon water; typically,
at this concentration, either centrifugal pumps or a combination of
centrifugal pumps and eductors are used to transport the carbon slurry.
Diaphragm slurry pumps or double-acting positive displacement pumps are
used for transporting higher concentrations. Another transport method
used is a pressure pot system in which carbon is loaded into a pressure
tank and forced out by pressurizing the vessel. The carbon slurry may be
fed using a rotodip feeder.
Activated carbon is a dusty respiratory irritant which smolders if
ignited. Activated carbon should be isolated from flammable materials
such as rags, chlorine compounds and all oxidizing agents.
Soda Ash
Dense soda ash is generally used in municipal applications because of
superior handling characteristics. It has little dust, good flow character-
istics, and will not arch in the bin or flood the feeder. It is relatively
hard to dissolve and ample dissolver capacity must be provided. Normal
practice calls for Q£5, Ib of dense soda ash per gallon of water or a 6 percent
solution retained fot^ZO minutes in the dissolver. Dissolving of soda ash
may be hastened by the use of warm dissolving water. Mechanical or hydraulic
jet mixing should be provided in the dissolver.
Sodium Aluminate
Dry sodium aluminate is not available in bulk quantities; therefore,
small day-type hoppers with manual filling arrangements are used. Dissolvers
for the free-flowing grade of sodium aluminate are normally sized for 0.5
Ib per gallon or 6 percent solution strength with a dissolver detention time
of 5 minutes at the maximum feed rate. After dissolving, agitation should
be minimized or eliminated to prevent deterioration of the solution. Solution
tanks should be covered to prevent carbonation of the solution.
Liquid sodium aluminate may be fed at shipping strength or diluted
to a stable 5 to 10 percent solution. Stable solutions are prepared by
direct addition of low-hardness water and mild agitation. Air agitation is
not recommended.
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Sodium Chlorite
Sodium chlorite (NaCl02) for the generation of chlorine dioxide is
available as an orange powder or as a solution.
The sodium chlorite pump is sized so as not.to exceed a solution strength
of 20 percent by weight (0.20 kg/i (1.66 lb/gal)). Diaphragm pumps rather.
than piston pumps normally are used for"handling .the .solutions. .The solution
container for sodium chlorite is sized for at least one day's operation.
Sodium ch£orij-e"will withstand considerable rough handling if it is free
from qrganic matter. However, in contactwith organic materials (clothing,
sawdust, brooms), it may ignite. It is sensitive to heat, friction, and
impact.. These problems' are minimized with sodium chlorite solutions.
* " ' " ,
Sodium Hydroxide , ., " v . .. ......... ,
Liquid sodium hydroxide, or caustic;soda, is usually delivered in bulk
shipments and must then be transferred to., storage. The caustic soda is often'
heated and fed by metering pumps as a concentrated solution. Dilution water
is usually added after feeding to the pump discharge line. Feeding systems
for caustic soda are about the same as for liquid alum except for materials
of construction. ..._...., , ...._..,,
Caustic soda is poisonous and dangerous if handled improperly. To
avoid accidental spills, all pumps, valves and lines should be checked
regularly for leaks. Operators should be properly Instructed in the
precautions related to the safe handling of this chemical.
STORAGE '. . .. . : . " .. . '"... , ' ;'",";" '. '". ."_'
The equipment used for storing and handling chemicals varies with
the type of chemical used, liquid or dry form of the chemical, quantity of
chemical, used, and planl: size. Storage requirements vary,'but typically
may be 15 to 30 days of use or 150 percent of the bulk transport capacity,
whichever is greater.
It is also important to recognize that there may be special precautions
necessary for the safe unloading and storage of certain chemicals. Because
it is not practical to provide a complete discussion of these precautions
in this manual, it. is recommended that the operator obtain such.information
directly from the chemical manufacturer before implementing a.chemical
storage and handling system.
Unloading
Chemicals can be delivered to a wastewater treatment plant in dry,
liquid or gaseous form. Dry chemicals are generally available in either
bagged or bulk form. Where daily requirements are small; bagged'chemicals
85
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are preferred and the handling and storage operations are relatively simple,
usually involving either manual labor or mechanical aids. Bagged chemicals
are delivered in loose bags or palletized in trucks or box cars and are
generally transferred by hand truck or fork lift to storage. Unloading
conveyors may be preferred for loose bags, especially if there is a long
distance between the unloading point and storage area. Palletized bag ship-
ments, with fork lift trucks moving the loaded pallets to storage and then to
the point of use, eliminate much manual labor.
Bulk quantities of dry or liquid chemicals are delivered in trucks or
by rail in box cars -.and hopper cars. Bulk unloading facilities usually must
be provided at the treatment plant. Rail cars are constructed for top
unloading and therefore require an air supply system and flexible connectors
to pneumatically displace the chemical from the car. The United States
Department of Transportation regulations concerning chemical tank car
unloading should be observed. A typical pneumatic conveying system for dry
chemicals is shown in Figure 21. Unloading of liquid chemicals from a tank
truck is usually accomplished by gravity or by a truck-mounted pump.
Chlorine (as well as ammonia and sulfur dioxide), classified by the
U.S. Department of Transportation and the U.S. Coast Guard as a nonflammable
compressed gas, must be packaged in containers that comply with DOT and/or
Coast Guard regulations regarding loading, handling, and labeling when
shipped in the United States by rail, water or highway. Chlorine gas is
commonly available in 100 Ib and 150 Ib steel cylinders, in ton containers,
and also in large quantities in tank cars (rail), tank trucks, and barges.
Various mechanical devices, such as skids, troughs, and up-ending
cradles facilitate handling of chlorine cylinders. When unloading from
trucks or platforms, cylinders must not be dropped to ground level. If
cylinders must be lifted and an elevator is not available, specially
designed cradles or carrying platforms in combination with a crane or
derrick are recommended; chains, lifting magnets, and rope slings that
encircle the cylinders are unsafe and should not be used. For lateral
movements a properly balanced handtruck is useful. Cylinders being moved
should always have valve protection hoods in place; these hoods are not
designed to hold the weight of cylinders and their contents, and cylinders
should never be lifted by this means.
Ton containers may be moved by various methods, such as by specially
fitted trucks and dollies, a monorail system, or rolling. Where it is
necessary to lift them, as from a TMU car or truck, a suitable lift clamp
in combination with a hoist or crane of at least 2-ton capacity should be
used. Valve protection hoods should always be in place when ton containers
are being moved.
Receiving and unloading areas and safety precautions applicable to
handling single-unit railroad tank cars, tank trucks, and other shipping
containers are subject to strict regulations.
86
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87
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Bulk Storage
A typical bulk storage tank or bin for dry chemicals is shown in
Figure 22. Dust collectors should be provided on manually and pneumatically
filled bins. The material of construction and. the required slope on the bin
outlet vary with the type of chemical stored; in addition, some dry chemicals
such as lime must be stored in air-tight bins to keep moisture out.
Bulk storage bins should have a discharge bin gate so feeding equipment
can be isolated for servicing. The bin gate should be followed by a flexible
connection and a transition chute or hopper which acts as a conditioning
chamber over the feeder (shown previously in Figure 5).
Liquid storage tanks should be sized according to maximum feed rate,
shipping time required, and quantity of shipment. The total storage
capacity should be 1^ times the largest anticipated shipment, and should
provide at least a 10-day to 2-week supply of the chemical at the design
average dose. Storage tanks for most liquid chemicals may be located
inside or outside; however, outdoor tanks must usually be insulated and/or
heated to prevent crystallization. Storage tanks for 'some liquids, such as
liquid caustic soda, should be provided with an air vent for gravity flow.
Liquid storage tanks can be located either at ground level or above
ground level, depending upon whether gravity feed or pressure feed is
desired at the point of application. Figures 23 and 24 show two common
liquid feed systems, one with overhead storage and one with ground storage.
The rotodip-type feeder or rotameter often is used for gravity feed and the
metering pump for .pressure feed systems. Overhead storage can be used to
gravity feed the rotodip as shown in Figure 23. A centrifugal transfer pump
may also be used, but needs an excess flow recirculation line to the
storage tank, as shown in Figure 24.
Bag and Drum Storage
In general, bags or drums should be stored in a dry, cool, low humidity
area and used in proper rotation, i.e., first in, first out. Bag or drum
loaded hoppers should have storage capacity for eight hours at the nominal
maximum feed rate so personnel are not required to fill or charge the
hopper more than once per shift.
Cylinder and Ton Container Storage
Whether in storage or in use, cylinders should not be permitted to
stand unsupported. They should be chained to a fixed wall or support, and
in such a manner as to permit ready access and removal. Ton containers
should be stored horizontally, slightly elevated from ground or floor level,
and blocked to prevent rolling: a convenient storage rack is obtained by
supporting both ends of containers on rails of I-beams. Ton containers should
not be stacked or racked more than one high unless special provision is made
for easy access and removal. Chlorine cylinders and containers should be
protected from impact, and handling should be kept to a minimum. Full and
empty cylinders and ton containers should be stored separately.
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90* BEND
4' Min. Rod.
DUST COLLECTOR
SAFETY VALVE
HIGH LEVEL
INDICATOR
LOW LEVEL
INDICATOR
VIBRATOR
4" PIPE
60° CONE
QUICK
COUPLING
\UU » ^*" i
F
G— -
.•
\;
• *
To Feeder
(OR AIR PADS)
•ffgj^f
Figure 22, Typical bulk storage tank.
89
-------
OVERHEAD
STORAGE
TANK
Control
valve-j
-Rotodlp—type
feeder
Relief
valve
/Back pressure
V valve
Rotameter
Metering pump
Gravity feed
Gravity feed
Gravity feed
Figure 23. Alternative liquid feed systems for overhead storage.
Pressure feed
f Rotodlp—type feeder
Control valve
Rotameter
Reclrculatlon
Gravity feed
Transfer pump
GROUND
STORAGE
TANK
Relief
valve
Centrifugal
feed pump
,1.1
g
Pressure
feed
Metering
Figure 24. Alternative liquid feed systems for ground storage.
-Back pressure
valve
90
-------
Storage areas should be clean,"cool, wel^Ventilated, and protected
from corrosive vapors and continuous dampness. Cylinders and ton containers
stored indoors should be in a fire-resistant building, away from heat sources
(such as radiators, steam pipes, etc.), flammable substances, and other
compressed gases. Subsurface storage areas should; be avoided, especially
for chlorine and sulfur dioxide. If natural ventilation is inadequate,
as would be the case for chlorine, storage and use areas should be equipped
with suitable mechanical ventilators, Cylinders and ton containers stored
outdoors should be shielded from direct sunlight and protected from
accumulations of rain, ice and snow. ;
All storage, handling, and use areas should be of such design that,
personnel can quickly escape in emergencies. It is generally desirable
to provide at "least two ways to exit. Doors' should open out and lead to
outside galleries or platforms, fire escapes, or other unobstructed areas.
PIPING AND HANDLING MATERIALS . •'.
Piping and accessories for transporting and feeding various chemicals
should be provided qnly after specific chemicals have, been selected for
use in the treatment plant. Care must be taken to use only materials ^ -
which are compatible with each chemical. For example, many chemical handling
systems require special materials of construction and special types of:
• Piping and Transport Channels
• Pumps
• Valves
• Gaskets » ' ' '' ""••*"'
Table 24 shows a summary of acceptable materials for piping and ...
accessories for several commonly used chemicals. This table is .not all- .
inclusive, but will provide the operator with a quick reference on material
compatibility for most common chemicals. Because sodium hydroxide (caustic
soda) is .particularly dangerous to handle and requires special considera-
tion, more detailed information on feeding and handling equipment for this
chemical.is listed in Table 25. The operator .also is referred to the Appendix
of this manual for a more general'listing of acceptable handling materials
for each chemical. , '
MANUAL AND FLOW PACING "CONTROL .FOR,,CHEMICAL FEED SYSTEMS
There are three frequently encountered chemical feed systems: (1) dry
feeders, (2) solution feeders, and (3) gas feeders. Each type of feeder
should have one or more means to adjust the chemical feed rate (dosage)
easily. The adjustment(s) may be manual or flow pacing and must be accurate,
repeatable, and easy to change. They should also provide the broadest
possible adjustment span from minimum to maximum feed rate. Typical ranges
are 10:1 to , 20.: 3Ubut, greater .ranges are. possible, as shown previously,.in,.Table 23.
91 •
-------
TABLE 24
Compatible Materials for Piping and Accessories of Commonly Used Chemicals
CHEMICAL
ALUM
PIPES
VALVES
SODIUM ALUMINATE
PIPES
FERRIC CHLORIDE
PIPES
VALVES
FERRIC SULFATE
PIPES
LIME
PIPES & CHANNELS
PUMP IMPELLER LINING
SODIUM CARBONITE
PIPING
SODIUM HYDROXIDE
PIPING
CARBON DIOXIDE
(COOL & DRY)
CARBON DIOXIDE
(HOT & MOIST GAS)
CARBON DIOXIDE
(SOLUTION)
POLYMER (DRY)
PIPING
r
•
•
•
•
JlM
I, / 03 1 GO/ Co/ t
/ i^// *°i ^7 fi
•
•
•
•
•
•
•
•
•
•
•
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•
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v/ii
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(ALSO SEE TABLE 25
* FRP-Fiber reinforced plastic
92
-------
TABLE 25
Materials Suitable for Caustic Soda Systems
Components
Rigid Pipe
Flexible Connections
Diluting Tees
Fittings
Permanent Joints
Unions
Valves - Non-leaking (Plug)
Body
Plug
Pumps (Centrifugal)
Body
Impeller
Packing
Storage Tanks
Recommended Materials for Use With
50% NaOH Up to 140°F
Standard weight black iron
Rigid pipe with ells or swing
joints, stainless steel or
rubber hose
Type 304 stainless steel
Steel
Welded or screwed fittings
Screwed steel
Steel
Type 304 stainless steel
Steel
Ni-Resist
Blue asbestos
Steel
93
-------
Dry Feeders
Most dry feeders are of the belt, grooved disc, screw, or oscillating
plate type. The feeding device (belt, screw, disc, etc.) is usually driven
by an electric motor. Many belt feeders, particularly gravimetric type
feeders, also contain a material flow control device such as a movable gate
or rotary inlet device for metering or controlling the flow of chemical to
the feed belt.
Volumetric Dry Feeders—
Most volumetric dry feeders are of the rotating screw or disc type,
but the belt and rotary star valve types are also used. Generally, the
screw or disc type is driven by an electric motor through a gear reducer
drive. In some cases the drive assembly (excluding the motor) contains
a variable speed or a linkage adjustment which allows feed rate changes.
Otherwise, the feed rate adjustment must be made directly to the motor
drive.
Manual Feed—Manual dosage adjustment of volumetric dry feeders is
accomplished by one or more of the following means:
1.
Drive motor for feed screw, belt, disc, or rotary valve.
a. Manual variable speed.
b. Percentage timer control motor which operates on a run-stop
repeat cycle with run time set by percentage timer and adjust-
able from zero to 100 percent of the total cycle. Typical
total run-stop cycle times are 15, 30, 60 seconds. For a
system set up on a 60-second basis the following is typical
operation:
Percentage
timer setting
100
75
50
25
, 0
Run time,
seconds
60
45
30
15
0
Off time,
seconds
0
15
30
45
60
c. Manually adjustable speed reducer or adjustable linkage
on drive assembly.
2. Control gate for belt feeder.
a. Manual setting of gate position to allow more or less material
on belt.
Flow Pacing—Automatic proportioning of volumetric dry feeders to flow
(commonly called flow pacing) is readily accomplished for a variety of flow
signals. The more common flow and control signals are:
a. Pulse duration (on-off), with frequently used cycle times of 15,
30, and 60 cycles.
94
-------
b. 3 - 15 psi pneumatic
c. 4 - 20 or, 10 - 50 milliampere
d. 1 - 5 'volt d.c. , , ...... ,
Most modern feeders can accept one or more of the flow and control
signals. If the feeder will, not accept the particular signal available,
signal converters are readily available to convert the signal to one that
the feeder will accept. For example, a 3 - 15 psi pneumatic signal can
be converted to a 4- 20 mA signal. Signal converters are relatively
inexpensive and"are reliable.
If a^volumetric feeder is automatically flow-proportioned, a means
still must be available for setting the feed dosage. Typically, this is
accomplished In one of two ways.
1.
2.
A "manual feed rate control" built into the feeder which modifies
the automatic proportioning signal within the feeder control system.
A separate.manual adjustment such as a mechanical linkage or feed
gate adjustment, or a manual speed adjustment on the gear reducer
drive system.
Gravimetric Dry Feeders—
Manual Feed— A gravimetric dry feeder has a built-in control system
to maintain a constant feed weight rather than volume for any given dosage
setting. For manual feed systems, an operator dosage adjustment is provided
as part of this gravimetric control system. The feed belt is weighed
continuously, establishing automatic internal control of gate position (or
rotary inlet valve speed) to maintain a constant belt weight for a given
dosage setting. . •
Flow Pacing—The simplest method to obtain automatic proportioning
control is to provide a variable speed drive for the belt. The automatic
proportioning control can be used to vary the belt-drive motor speed.
If the feeders are to be shut down automatically, for instance when
incoming wastewater flows are low and not all feeders are required, provisions
should be made for shut-down and start-up of system components such as:
a. The feeder . ,
b. Storage bin vibrators '
c. Water supply to dissolvers
-^ - • • . - -.
d. Mixers
e. Solution transfer pumps
.95
-------
Dissolver water supply and mixer should operate for an adjustable time
delay after the feeder is stopped to prevent chemicals from settling in
the dissolver.
Solution Feeders
The most common solution feeders are motor-driven diaphragm and plunger
type feed pumps. Generally, these pumps have a built-in stroke adjustment
mechanism which permits variation of the output feed rate.
Manual Feed—
For manual dosage control, the motor would operate at a constant speed
and the operator could adjust the dosage with the stroke adjustment.
Flow Pacing—
Automatic proportioning control can be accomplished readily in one of
the following ways:
1. Modification of drive motor to provide variable speed or on-off
propert ioning.
2. Installation of an automatic stroke adjuster.
The drive motor can be set up to operate at variable speeds proportional
to pneumatic or electric signals. On-off pulse duration signals can be applied
directly to the motor starter so that the motor operates on and off in
proportion to the signal. This involves many start-stop cycles for the motor
and it is recommended that only three phase motors be used for this type of
duty. When the automatic proportioning is accomplished with the drive motor,
the manual stroke adjustment is still available for operator-adjusted manual
dosage changes.
Automatic stroke adjusters can be installed in place of the manual
adjuster on most feeders. The automatic adjusters will accept various analog
control signals, including pneumatic and electric. Obviously, these automatic
stroke adjusters can be used for automatic proportioning, but in most cases
there are not manual settings available for manual dosage adjustments. In
some cases, a manual dosage adjustment can be incorporated into the automatic
stroke adjustment mechanism or a manual variable speed motor drive can be
provided for operator manual dosage adjustment. Probably the most satisfac-
tory arrangement is to proportion automatically with a variable speed or pulse-
duration motor drive, and to leave the manual stroke adjuster for operator
dosage adjustments.
If the solution feed system is to be started and stopped with plant
operation or on some other basis, consideration must be given to starting
and stopping auxiliary systems such as the solution feeder, dilution water,
transfer pumps, mixers, and similar equipment.
There are a number of solution batching and feed systems now on the
market, particularly for polymers. These systems automatically produce a
96
-------
feedable polymer solution from dry polymer. Typical systems include a dry
polymer storage hopper, dry feed, wetting, a dissolver tank with mixing,
a feed tank, and solution feeders. Most of these systems are sold as a pre-
engineered package and can be supplied for manual control, automatic propor-
tioning and for automatic start and stop operation. Generally, these systems
use solution feed pumps for metering and the previous comments concerning
solution feeders are applicable.
Gas Feeders
Most modern gas feeders are vacuum operated. The gas is accurately
metered through an orifice with a fixed pressure drop across the orifice.
For adjustment of gas feed rate the orifice size can be changed manually or
automatically.
Manual Feed—
Most small, inexpensive gas feeders have provisions for.manual adjustment
of the orifice size to change the gas-flow rate (dosage). This adjustment
is made with a knob on the front of the feeder. Normally the gas flow rate
is indicated by a visual flow indicator calibrated in pounds per day.
Flow Pacing— , . - .
Gas feeders may be automatically proportioned in a number of ways. Two
common methods are variable vacuum control and automatic positioning of the
orifice control. .
Variable Vacuum Control—Variable vacuum control systems are an economical
method of automatically proportioning gas feeders. The vacuum control system
consists .basically, of.-a vacuums-producing-device, such as the gas injector, a
restricting orifice and an intermediate vacuum transmitter. The primary flow
signal is converted to a proportional vacuum signal which is applied to the
vacuum-regulating valve on the. downstream side of the gas feeder orifice.
The pressure ahead of the orifice is maintained at a constant value by the
inlet gas pressure regulating valve. The gas feed rate is varied automatically
as this proportioning vacuum signal changes with the flow.
Changes in the control vacuum signal cause comparable changes in the
pressure downstream of the orifice and, therefore, in the differential
across the orifice. Since the gas flow squared is proportional to the
differential pressure across the orifice, the gas-feed rate will vary in
accordance with the control-vacuum signal.
Automatic Positioning—Automatic positioning of the gas-flow control
orifice is accomplished with a power positioner which can be selected to
operate from a number of input signals such as:
a. 3-15 psi pneumatic
b. 4 - 20 or 1 - 50 milliampere electric
c. 1-5 volt d.c. electric
97
-------
d. Potentiometer position
e. Pulse duration
f. Ptijse frequency
g. Others by special application
When an automatic proportioning positioner is used, a manual dosage
control knob is provided on the chlorinator so the operator can make manual
adjustments of dosage. This adjustment modifies the automatic proportioning
over a wide range.
Almost all gas-feeder control schemes are based on the use of variable
vacuum or the use of an orifice-proportioning positioner. In most cases,
the manual dosage adjustment is retained for operator use.
Gas feeders can be started and stopped simply by starting or stopping
water flow through the injector. Usually this is all that is necessary to
start or stop a typical gas-feed system such as a chlorinator or sulforator.
AUTOMATIC CONTROL FOR CHEMICAL FEED SYSTEMS
Various automatic control schemes are possible for chemical feed systems
beyond the automatic flow proportioning discussed for each type of feeder.
For example, automatic pH control is possible using a pH sensor, controller,
and pH adjustment chemical feeder for sodium hydroxide with an automatic
stroke positioner. Automatic chlorine residual control is possible using a
chlorine residual analyzer, controller, and chlorinator with an automatic
orifice positioner. These are "feed back" systems where the final control
parameter, such as pH, is controlled by a previous feed of chemical. "Feed
forward" systems are also possible where a parameter concentration prior to
chemical feed is determined and related to the chemical feed for automatic
control. An example is ammonia removal by breakpoint chlorination. Approx-
imately 8 to 10 parts of chlorine are required to remove one part of ammonia.
Therefore, if the ammonia concentration prior to chlorine feed is measured,
the chlorine feed can be proportioned to 8 or 10 times the ammonia
concentration.
Various types of "feed forward" or "feed back" systems or combinations
can be devised in theory. The problem is that there are substantial delay
times in such systems which most analog controllers are not designed to
handle. The delays are mostly hydraulic in the time to change a chemical
feeder setting, get the change to the injection point, process delays to the
sample point, delay in the sample lines and delay in the analyzer. The
total delay from the time a feed rate is changed until it is read out by an
analyzer can be 5 minutes or longer. The control results can be unstable
and can lead to wide cycles of the controlled variable. There are ways of
overcoming these problems with proper design and equipment selection, but
design of such systems is a very specialized art.
98
-------
ri.«. i+gl = -"rK^"''1 ' '
Automatically controlled systems must "be arranged so that auxiliary
systems such as mixers, dilution water, and slakers are started and stopped
as needed. The point to be emphasized, therefore, is that such systems can
be designed and applied where needed and that chemical feeders are available
for use in such systems. These systems are complex enough and the analyzers
require maintenance to the point that such systems should not be used except
where they provide a benefit sufficient to overcome the operational
disadvantages.
99
_Q
-------
SECTION 4
References
1. "Field Manual for Performance Evaluation and Troubleshooting at Municipal
Wastewater Treatment Facilities," EPA 430/9-78-001, January 1978.
2. WPCF, Manual of Practice No. 11, "Operation of Wastewater Treatment
Plants," 1976.
3. AWWA, Manual M20, "Water Chlorination Principles and Practices," 1973.
4. "Manual of Instruction for Water Treatment Plant Operators," New York
State Department of Health.
5. "Process Design Manual for Phosphorus Removal," EPA^ Technology Transfer,
EPA 625/1-76-OOla, April 1976.
6. WPCF, Manual of Practice No. 8, "Wastewater Treatment Plant Design,"
1977.
7. "Sludge Handling and Conditioning," EPA 430/9-78-002, February 1978.
8. "Lime Handling, Application and Storage," Bulletin 213, National Lime
Association, Second Edition, May 1971.
9. White, G. C., "Handbook of Chlorination," Van Nostrand Reinhold Company,
1972
10. "Chlorine Manual," 4th Edition, The Chlorine Institute, 1969.
11. White, G.C., "Disinfection of Wastewater and Water for Reuse," Van
Nostrand Reinhold Company, 1978.
100
-------
SECTION 5
PROBLEMS TffilCH CAN BE AIDED BY CHEMICAL ADDITION
-------
-------
SECTION 5
PROBLEMS WHICH CAN BE AIDED BY CHEMICAL ADDITION
This section of the manual serves primarily as a troubleshooting
guide to help identify problems which can be aided by the addition of
chemicals. Problems are identified by the treatment process where the
problem would most likely occur. A possible solution is provided for
each problem, along with a list of possible chemicals for aiding the
problem, advantages and disadvantages of each chemical, and potential
application points.
While chemical addition may be helpful in many wastewater treatment
processes, it must be recognized that there may be operational alternatives
which are less expensive and more desirable. OPERATIONAL ALTERNATIVES
SHOULD BE INVESTIGATED THOROUGHLY BEFORE CHOOSING A CHEMICAL ALTERNATIVE
DESCRIBED IN THIS SECTION. In some cases, short-term correction using
chemicals may be necessary, but the condition causing the problem also
must be identified and corrected. This is particularly true when the
problem is associated with an industrial discharge, lack of enforcement
of pretreatment requirements, or an overloaded plant. CHEMICALS SHOULD
NOT BE USED AS A SUBSTITUTE FOR GOOD PLANT OPERATING PROCEDURES.
For more information on troubleshooting and process control, the
operator should refer to "Field Manual for Performance Evaluation and
Troubleshooting at Municipal Wastewater Treatment Facilities," EPA-430/9-
78-001, January 1978. This manual describes procedures for evaluating
and troubleshooting various unit processes commonly used at wastewater
facilities. One chapter is devoted to chemical feeding and conditioning,
and other chapters contain information on the use of chemicals in improving
process operations. Procedures for evaluating process efficiencies also
are included! :
101
-------
A.
B.
INDEX
TO
PROBLEMS WHICH CAN BE SOLVED BY CHEMICAL ADDITION
Treatment Processes
Collection Systems
Pump Stations and Pipelines
Conventional Wastewater Treatment
Page Number
106
Preaeration 109
Grit Removal 110
Microscreening Ill
Primary Clarification 112
Trickling Filter 116
Activated Sludge 118
Rotating Biological Contactors 120
Lagoons 121
Secondary Clarification 122
Disinfection . 124
Dechlorination . 125
C. Advanced Waste Treatment
Tertiary Chemical Clarification 127
Nitrogen Removal 129
Filtration 130
Activated Carbon Adsorption 131
D. Sludge Treatment and Conditioning
Anaerobic Digestion 133
Aerobic Digestion 135
Gravity Thickening 136
Flotation Thickening 137
Centrifugation 138
Sludge Drying Beds 139
Vacuum Filtration ..... 140
Filter Press ..... 141
Land Application of Sludge 142
102
-------
COLLECTION SYSTEMS
103
-------
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140
-------
SECTION.5
References
1. "Field Manual for Performance Evaluation and Troubleshooting at
Municipal Wastewater Treatment Facilities," EPA 430/9-78-001,
January 1978. ,
2. "Process Design Manual for Upgrading Existing Wastewater Treatment
Plants," EPA, Technology Transfer, 625/l-71-004a, 1974.
3. "Process Design Manual for Phosphorus Removal," EPA, Technology
Transfer, EPA 625/1-76-OOla, April 19.76. . , , ,
4. "Process Design Manual for Suspended Solids Removal," EPA, Technology
Transfer, EPA 625/1-75-003a, January 1975.
5. "Process Design Manual for Nitrogen Control," EPA, Technology
Transfer, October 1975.
6. "Process Control Manual for Aerobic Biological Wastewater Treatment
Facilities," EPA 430/9-77-006,- March 1977. .,-.
7. "Process Design Manual for Sludge Treatment and Disposal," EPA,
Technology Transfer, 625/1-79-011, September 1979.
141
-------
-------
APPENDIX
INFORMATION ON CHEMICALS
-------
-------
APPENDIX
INFORMATION ON CHEMICALS
General information on various chemicals is provided in this
section,including uses of the chemical, trade and common names,
available forms, commercial strength, feeders, storage, safety
considerations, approximate 1979 cost, acceptable handling materials,
and major chemical manufacturers. For easy reference, the chemicals
are arranged in alphabetical order.
The information provided in this Appendix is intended to provide,
the operator with basic guidance on the use and handling of different
chemicals. There is much useful information in the Appendix, but the
operator must be aware of certain limitations. Most chemicals are
shipped in a variety of forms, quantities, and commercial strengths
which may differ with each manufacturer or supplier. Consequently,
the Appendix describes the most commonly available form for each
chemical. Storage and safety information described in the Appendix is
not intended to be complete or absolute. Sufficient general information
is provided to aid the operator in deciding whether or not to use a
certain chemical; however, detailed information on specific chemicals
should be obtained directly from the supplier before purchasing or using
the chemical in question.
The cost quotations in this section are approximate 1979 costs
obtained from,the "Chemical Marketing Reporter," November 5, 1979.
The costs reflect the list prices of merchant producers prevailing on
November 2, 1979 for large lots, f.o.b., New York. The values do not
represent bid and asked prices. Differences between high and low costs
may be accounted for by differences in quantity, quality or locality.
Because it is not possible or practical to identify all manufacturers
or suppliers of each chemical, the operator is strongly encouraged to add
his own local supplier to the list wherever possible. A partial list of
manufacturers is provided in the Appendix only as guidance for locating
a possible source for chemicals which may otherwise be difficult to
obtain.
A-l
-------
APPENDIX INDEX
Chemical Paee
Activated Carbon A-3
Aluminum Sulfate i A-4
Anhydrous Ammonia A-5
Bentonite A-6
Calcium Carbonate • A-7
Calcium Hydroxide A-8
Calcium Hypochlorite A-9
Calcium Oxide A-10
Carbon Dioxide A-ll
Caustic Soda A-12
Chlorine A-13
Copper Sulfate • • A-14
Defoamer A-15
Diatomaceous Earth A-16
Ferric Chloride A-17
Ferric Sulfate • • A-18
Ferrous Chloride • A-19
Ferrous Sulfate • A-20
Hydrochloric Acid . . . . . A-21
Hydrogen Peroxide A-22
Lime A-23
Magnesium Hydroxide • A-24
Methanol A-25
Oxygen (Liquid) ....... A-26
Ozone A-27
Polymer • A-28
Potassium Permanganate A-29
Soda Ash A-30
Sodium Aluminate A-31
Sodium Bicarbonate A-32
Sodium Bisulfite A-33
Sodium Carbonate . • A-34
Sodium Hydroxide A-35
Sodium Hypochlorite A-36
Sodium Metabisulf ite A-37
Sodium Sulfite A-38
Sodium Thiosulfate A-39
Sulfur Dioxide A-40
Sulfuric Acid A-41
A-2
-------
ACTIVATED CARBON
TRADE NAMES
Aqua Nuchar, Norit, Darco, Carbodur
AVAILABLE FORMS
Bags.r 35 Ib.
Drums - 5, 25 Ib.
Bulk - Carloads ,
STORAGE
Bags, bins
APPROX. 1979 COST
$0.61-$0.65/lb
USES
Taste, odor, color and organics
removal, dechlorination, sludge
stabilization, denitrification.
COMMERCIAL STRENGTH
10% C (bone char) to 90% C (wood
charcoal)
FEEDERS
Gravimetric - L-I-W
Volumetric - helix (Fig. 9)
Slurry ^ rotodip or diaphragm pump
' (Fig. 13)
SAFETY CONSIDERATIONS
'Dusty, smolders if ignited. Isolate
from flammable materials such as
rags, chlorine compounds, and all
oxidizing agents.
HANDLING MATERIALS
Dry - iron, steel
Wet' - rubber, iron, steel
MAJOR MANUFACTURERS
American Norit Company, Inc., 6301 Gli'dden Way, Jacksonville, Florida 32208
Westvaco Corporation, Chemical Division, Covington, Virginia 24426,.
Whitco Chemical Corporation, 277 Park Avenue, New York, New York 10017
ICI United States, Ihc". , Wilmington, Delaware 19897
Calgori Corporation, P.O. Box 1346, Pittsburg, Pennsylvania 15230
A-.3
-------
ALUMINUM SULFATE
TRADE NAMES
Alum, filter alum
AVAILABLE FORMS
Dry
Bags - 100, 200 Ibs
Bbls - 300, 400 Ibs
Drums - 25 100 250 Ibs
Bulk - carloads , tank trucks
Liquid
Rail or truck - 4000 gal (min)
STORAGE
Dry Alum - 30 days max, in dry loca-
tion with dust collectors. Use 60°
min hopper wall slope to prevent
arching.
Liquid - corrosive, store without
dilution above 25°F to prevent
crystalization
APFROX. 1979 COST
$146-$165/ton
USES
Coagulation, sludge conditioning,
precipitate P04, remove metals, oil,
organics, BOD/SS.
COMMERCIAL STRENGTH
Powder - 17% Al2 03
Minimum Liquid - 8.3% as Al2 03 or
49% as A12 (804)3.14 H20
FEEDERS
Gravimetric - belt, (Fig. 10,11'), L-l-W
Volumetric - helix (Fig. 9),
universal (Fig. 7)
Solution — rotodip, plunger or
diaphragm pump, (Figure 13 )
SAFETY CONSIDERATIONS
Dry alum is dusty, irritating to
mucous membranes, can cause serious
eye injury.
HANDLING MATERIALS
Solution - Stoneware, lead, rubber, acid-resisting tile, Duriron, plastics,
stainless 316, asphalt, cypress, PVC, Fiberglass
Dry - concrete, steel, iron
MAJOR MANUFACTURERS
American Cyanamid, Berdan Avenue, Wayne, New Jersey 07470
Allied Chemical Corporation, P.O. Box 1139R, Morristown, New Jersey 07960
Ashland Chemical Company, P.O. Box 2219, Columbus, Ohio 43216
Dixie Chemical Company, 3635 W. Dallas Street, Houston, Texas 77019
Cities Service Company, 3445 Peachtree Road, Atlanta, Georgia 30302
Stauffer Chemical Company, New York, New York
'A-4
-------
ANHYDROJJS AMMONIA
TRADE NAMES
Ammonia
USES
Chlorine-ammonia treatment, anaerobic
digestion, nutrient for aerobic
bacteria
AVAILABLE FORMS
Cylinders - 50, 100, 150 lb.
Tank Cars - 50,000 lb.
COMMERCIAL STRENGTH
99% to 100% NH3
STORAGE
Pressure cylinders
FEEDERS
Gas Feed
APPROX. 1979 COST
$120-$140/ton
SAFETY CONSIDERATIONS
Pungent, irritating odor, liquid causes
burns. Prevent contact with chlorine
compounds, mercury, iodine, and bromine
HANDLING MATERIALS
Iron,steel, glass, nickel, Monel, neoprene, Penton
MAJOR MANUFACTURERS
PPG Industries, Inc., Chemical Div., One Gateway Center, Pittsburgh, PA 15222
A-5
-------
BENTONITE
TRADE NAMES
Colloidal clay, WLlkinite, Volclay
USES
Coagulation aid as a weighting agent.
AVAILABLE FORMS
Bags - 50, 100 Ib
Bulk - carloads, railcars
COMMERCIAL STRENGTH
Not Applicable
STORAGE
Dry powder or granules. Provide
hopper agitation.
FEEDERS
Gravimetric - L-I-W, belt (Fig. 10,11)
Solution - diaphragm pump, plunger
pump (Fig. 13)
Volumetric -helix (Fig. 9), universal
(Fig. 7)
APPROX. 1979 COST
$28-$30/ton
SAFETY CONSIDERATIONS
No significant hazards
HANDLING MATERIALS
Iron, steel, Hypalon, Tyril
MAJOR MANUFACTURERS
Dow Chemical Corp., 2030 Dow Center, Midland, MI48840
A-6
-------
CALCIUM CARBONATE
TRADE NAMES
Calcite, limestone, whiting, chalk
USES
Neutralizing agent, corrosion control
AVAILABLE FORMS
Bags - 50 Ib
Drums ~
Bulk - carloads
COMMERCIAL STRENGTH
96 to 99%
STORAGE
Noncorrosive; store in concrete or
steel bins.
Provide hopper agitation.
FEEDERS
Gravimetric - L-I-W,belt (Fig. 10,11)
Volumetric - helix (Fig. 9) "
Slurry -.diaphragm pump (Fig. 13')
APPROX. 1979 COST
$54/ton
SAFETY CONSIDERATIONS
Slight dust hazard.~
Use protective clothing and devices
to avoid contact.
HANDLING MATERIALS
Iron, steel, rubber
MAJOR MANUFACTURERS
Clark Corp., P.O. Box 500, Windsor, WI 53598
A-7
-------
CALCIUM HYDROXIDE
TRADE NAMES
Hydrated lime, slaked lime
AVAILABLE FORMS
Bags - 50 Ib ,
Bbls - 100 Ib.
Bulk - carloads
STORAGE
Same as CaO but bin agitation must
be provided . Hopper should slope 65 .
APPROX. 1979 COST
$33-$43/ton
USES
Coagulation, pH adjustment, acid
neutralization, sludge conditioning,
precipitate POi^
COMMERCIAL STRENGTH
Ca (OH) 2 - 82-95%
CaO - 62-72%
FEEDERS
Gravimetric - L-I-W, belt (Fig. 10,11)
Volumetric - helix (Fig. 9), universal
(Fig.TJ
Slurry - rotodip, diaphragm or plunger
pump (Fig. 13 )
SAFETY CONSIDERATIONS
Caustic, irritant, dusty. Avoid eyes,
nose and respiratory system.
HANDLING MATERIALS
Rubber, iron, steel, cement, Hypalon, Penton, PVC, asphalt (no lead)
MAJOR MANUFACTURERS
Bethlehem Mines Corp., Annville, PA 17003
Mississippi Lime Co., 7 Alby Street, Alton, IL 62002
Ashland Chemical Co., P.O. Box 2219, Columbus, OH 43216
Flintkote Co., 1650 S. Alameda Street, Los Angeles, CA 90021
A-8
-------
CALCIUM.HYPOCHLORITE
TRADE NAMES
HTH, perchloron, Pittchlor
USES
Disinfection, slime control,
deodorization
AVAILABLE FORMS
Cans - 5 Ib
Drums - 100, 300, 800 Ib,
Bbls - 415 Ib.
COMMERCIAL STRENGTH
65% available Chlorine
Must be stored dry and cool; avoid
contact with organic matter
STORAGE
FEEDERS
LIQUID:
Rotodip, diaphragm pump (Fig. 13;
APPROX. 1979 COST
$0.70/lb
SAFETY CONSIDERATIONS
Corrosive
Avoid contact with organic matter.
HANDLING MATERIAL!
Ceramic, glass, rubber, PVC, Penton, Tyril, Hypalon, vinyl, stoneware, wood
(no tin)
MAJOR MANUFACTURERS
Ashland Chemical Co., P.O. Box 2219, Columbus, OH 43216 ~~''—
Dixie Chemical Co., 3635 W. Dallas St., Houston, TX 77019
PPG Industries, Inc., Chemical Div., One Gateway Center, Pittsburgh, PA 15222
Penwalt Corp., Inorganic Chemicals Div., Three Parkway, Philadelphia, PA 19102
A-9
-------
CALCIUM OXIDE
TRADE NAMES
Quicklime, unslaked lime, burnt lime
USES
Coagulation, pH adjustment, acid
neutralization, sludge conditioning,
precipitate
AVAILABLE FORMS
Bags - 50, 100 Ib.
Bbls - 100 Ib.
Bulk - carload
COMMERCIAL STRENGTH
70-96% CaO (can be poor quality
.below 85%)
STORAGE
Keep dry with container closed.
Store bags on pallets, 60 'flays maxi-
mum. Provide dust collectors for bin
storage and slope bin outlet 60 .
FEEDERS
Gravimetric^ - belt (Fig. 10,11) or
L-I-W
Volumetric - universal (Fig. 7), helix
(Fig. 9)
Also see Fig- 15 and 16 for lime
slakers.
APPROX. 1979 COST
$31-$33/ton
SAFETY CONSIDERATIONS
Unstable, caustic, irritant, dusty.
Lime dust and hot slurry can cause
severe burns.
HANDLING MATERIALS
Rubber, iron, steel, concrete, Hypalon, Penton, PVC, asphalt
MAJOR MANUFACTURERS
Pfizer Inc., MPM Div., 235 E. 42nd Street, New York, NY 10017
Bethlehem Mines Corp., Annville, PA 17003
Mississippi Lime Co., 7 Alby Street, Alton, IL 62002
Martin Marietta Cement, Southern Div., 18th Floor, Daniel Bldg, Birmingham, AL
35233
Ohio Lime Co., Woodville, OH 43469
Flintkote Co., 1650 S. Alameda Street, Los Angeles, CA 90021
U.S. Gypsum Co., Chemicals Division, 101 S. Wacker Dr., Chicago, IL 60606
A-10
-------
CARBON DIOXIDfe
TRADE NAMES
Dry ice, carbonic acid gas
USES
Recarbonation, coagulation/floe aid,
pH adjustment
AVAILABLE FORMS
Cylinders - 20, 50 Ib.
Trucks - 10, 20 tons
Railcar - 30, 50 tons
COMMERCIALS TREN 6 TH
99.5%
STORAGE
Pressure cylinders
Liquid systems usually require
on-site bulk storage.
FEEDERS
Gas feeder
APPROX. 1979 COST
$40-$80/ton (1974)
SAFETY CONSIDERATIONS
Colorless, odorless, nonflammable
gas. Solutions of CC>2 in water are
very reactive and, form carbonic acid.
HANDLING MATERIALS
As dry gas; iron, steel
As moist gas; 316SS, plastic
MAJOR MANUFACTURERS
Airco, Inc., Hopewell, VA; Lawrence, KS
Air Products & Chemicals, Inc., Pensacola, FL
Allied Chemical Corp.,_Geismar, LA; South Point, OH; Omaha, NB
American Cyanamid Co.,"New Orleans, LA
Chemetron Corp., Delaware City, DE; Morris, IL; Toledo, OH; Woodstock, TN; other
Chevron Chemical Co., Richmond, CA; Fort Madison, IA
Church & Dwight Co., Inc., Green River, WY
Ar-11
-------
CAUSTIC SODA
TRADE NAMES
See Sodium Hydroxide
AVAILABLE FORMS
STORAGE
APPROX. 1979 COST
USES
COMMERCIAL STRENGTH
FEEDERS
SAFETY CONSIDERATIONS
HANDLING MATERIALS
MAJOR MANUFACTURERS
A-12
-------
CHLORINE
TRADE NAMES
Chlorine gas, liquid chlorine
USES
Disinfection, slime control, taste and
odor control.
AVAILABLE FORMS
Cylinders - 100, 150, 200, 2,000 Ib.
Tank cars - 16, 30, 55 tons
COMMERCIAL STRENGTH
99.8% C12
STORAGE
Pressure cylinders
FEEDERS
Gas chlorinator
APPROX. 1979 COST
$195 - $230/ton
SAFETY CONSIDERATIONS
Pungent, noxious, corrosive gas,
health hazard. Prevent contact with
ammonia, acetylene, all petroleum
gases, hydrogen, turpentine, arid
benzene.
HANDLING MATERIALS
Gas - Copper, iron, steel
Liquid - glass, rubber, lead, silver
MAJOR MANUFACTURERS
Allied Chemical Corp., P.O. Box 1139R, Morristown, NJ 07960
Ashland Chemical Co., P.O. Box 2219, Columbus, Ohio 43216
Pennwalt Corp., Organic Chemicals Div. Three Parkway, Philadelphia, PA 19102
PPG Industries, Inc., Chemical Div., One Gateway Center, Pittsburgh, PA 15222
Dixie Chemical Co., 3635 W. Dallas St., Houston, TX 77019
A-13
-------
COPPER SULFATE
TRADE NAMES
Blue vitriol, blue stone, cupric
sulfate
USES
Algae control, root control in sewers
AVAILABLE FORMS
Bags - 100 Ib.
Bbls - 450 Ib.
Drums -
Bulk - carloads
COMMERCIAL STRENGTH
99% CuSO,
STORAGE
Store as received; chemical and its
solution are corrosive.
FEEDERS
Gravimetric - L—I-W
Volumetric - helix (Fig. 9)
universal (Fig. 7)
Solution - rotodip, diaphragm or
plunger pump (Fig. 13)
APPROX. 1979 COST
$42/100 Ib.
SAFETY CONSIDERATIONS
Poisonous in large amounts
HANDLING MATERIALS
Rubber, ceramic, 316SS, vinyl, Hypalon, PVC, Viton, epoxy, Tyril, asphalt
MAJOR MANUFACTURERS
Easton R.S. Corp., 4907 Farragut Rd., Brooklyn, NY 11203
Cities Service Co., Chemical Group Marketing, 3445 Peachtree Rd., N.E.
Atlanta, Georgia 30326
The Anaconda Co., Great Falls, MT
Southern California Chemical Co., Inc., Bayonne, NJJ Garland, TXJ
Santa Fe Springs, CAJ Union, IL
A-14
-------
DEFOAMER
TRADE NAMES
Exfoam 440, Wyandotte defoamer
AVAILABLE FORMS
Liquid - 5 and 55 gaL drums, bulk
Paste - 2 Ib., bulk , ' '
Dry - 2 Ib. bricks, bulk
STORAGE
Store in tight containers in cool,
shaded areas.
(Check with manufacturer for specific
defoamer)
APPROX. 1979 COST
$0.47-$0.66/lb.
USES
Foam removal in lagoons and
sludge
activated •
COMMERCIAL STRENGTH
Not applicable
FEEDERS
Solution - diaphragm pump (Fig. 13)
SAFETY CONSIDERATIONS
Avoid excessive handling, contact
with eyes, and ingestipn. Some ,
hydrocarbon base def darners may be
flammable.
HANDLING MATERIALS
Most common materials are acceptable. ••.•„••• •
Check with manufacturer for specific defoamer.
• •- -
MAJOR MANUFACTURERS
Drew Chemical Corp., 701 Jefferson Rd. , Parsippany, NJ 07054
Hercules Inc. , Industrial Systems Dept., Wilmington, Delaware 19899
Dearborn Chemical Div. , Chemed Corp., 300 Genessee St., Lake Zurich
BASF Wyandotte. Corp, Wyandotte, Michigan 48192
, IL 60047
A-.15
-------
DIATOMACEOUS EARTH
TRADE NAMES
Diatoms, celite, dicalite, celatom,
supercel, speedex, speed flow
USES
Filter aid, sludge dewatering with
pressure and vacuum.filters
AVAILABLE FORMS
Bags - 50 Ib.
Bulk
COMMERCIAL STRENGTH
Not applicable
STORAGE
Store dry as received
FEEDERS
Volumetric- helix (Fig. 9)
Gravimetric^, belt (Fig. 10,11), L-I-W
Slurry - diaphragm pump (Fig.13)
APPROX. 1979 COST
Variable, check with supplier.
SAFETY CONSIDERATIONS
Do not breathe excessive amounts of
dust.
HANDLING MATERIALS
Iron, steel, rubber, Tyril, Hypalon
MAJOR MANUFACTURERS
Johns-Manville, Filtration & Industrial Minerals Div., P.O. Box 5108,
Denver, Colorado 80217
Dicalite Div., GREFCO, Inc., 3450 Wilshire Blvd., Los Angeles, CA 90010
A-16
-------
FERRIC CHLORIDE
TRADE NAMES
Ferrichlor-j chloride of iron
.. • , ,../ ...
AVAILABLE FORMS
Solution
Car boys - 5, 13 gal. ..
Crystal
Kegs - 100, 300, 450 Ib.
Drums - 150, 350, 650 Ib.
" *
STORAGE
Store in tight containers as shipped
with free vent, coirosive in liquid
form
APPROX. 1979 COST
$100-$120/ton
USES
Coagulation at pH 4-11, :sludge
conditioning, precipitate PO,
COMMERCIAL STRENGTH
Solution - 35-45% FeCl^, 12-17% Fe
Crystal - 60% FeCl , 20% Fe
Anhydrous - 98% FeCl3, 34% Fe
FEEDERS
Solution - Diaphragm pump (Fig. 13.),
rotodip
No dry feed.
SAFETY CONSIDERATIONS
Corrosive in liquid form, avoid
contact with skin and -eyes. Induce
vomiting if ingested. . .
HANDLING MATERIALS
'Epoxy, rubber, ceramic, Hypalon, PVC, Penton, vinyl, stoneware, synthetic resin
MAJOR MANUFACTURERS
Ashland Chemical Co. , P.O. Box .2219, Columbus, ; Ohio 43216
Engineering Chemical Services, Inc., 40 Fulton St., New Brunswick, NJ 08902
Gulf Chemical & Metallurgical Co., P.O. Box 2130, Highway 519,
Texas City, Texas 77590 ' .
Dow Chemical Co., 2020 Dow Center, Midland, Michigan 48640
Pennwalt Corp., Inorganic Chemicals Div. , Three Parkway, PA 19102
Imperial West Chemicals, Antioch, California
/ . '
A-17
-------
FERRIC SULFATE
TRADE NAMES
Ferrifloc, ferriclear, iron sulfate,
ferrisul
AVAILABLE FORMS
Bags - 50, 100, 175 Ib.
Drums -200, 400, 425 Ib.
Bulk - car loads and truck loads of
50, 100 Ib. bags.
STORAGE
Store dry in tight containers of steel
or concrete and avoid moisture . Hopper
walls should slope 36% min. Do not
mix with quicklime in conveying or
dust vent systems.
APPROX. 1979 COST
$60-$74/ton
HANDLING MATERIALS
316SS, glass, rubber, plastic^ ceramic,
epoxy, Tyril, synthetic resin
MAJOR MANUFACTURERS
Cities Service Co., I.C.D., 3445 Peach
Gulf Chemical & Metallurgical Co., P.C
P^
tr<
. ]
USES
Coagulation at pH 4-6 and 8.8-9.2,
precipitate PO,
COMMERCIAL STRENGTH
68-94% Fe (S04)3
18.5-26% Fe
FEEDERS
Gravimetric - L-I-W
Volumetric - helix (Fig. 9),
universal (Fig. 7)
Solution — rotodip, diaphragm or
plunger pump (Fig. 13.)
SAFETY CONSIDERATIONS
• J 1 4- • 4 ,1 l>sN/4*
Corrosive in solution, avoid, oouy
contact
7C, Hypalon, lead, . vinyl, Penton,
se'Rd., N.E., Atlanta, GA 30326
3ox 2130, Hwy 519, Texas City, TX 77590
A-18
-------
FERROUS CHLORIDE
TRADE NAMES
Waste pickle liquor
USES
PC>4 removal, sludge conditioning
AVAILABLE FORMS
Bulk - tank trucks, car loads at
2,000 gal.
Drums - 50 gal.
COMMERCIAL STRENGTH
20-25% FeCl2 or 10% available iron
STORAGE
Since ferrous chloride may not always
be available, provide for storage and
handling of ferric chloride.
FEEDERS
Solution -
Diaphragm pump (Fig. 13),
Rotodip
APPROX. 1979 COST
$95-$103/ton
SAFETY CONSIDERATIONS
Slightly less corrosive than ferric
chloride
HANDLING MATERIALS
MAJOR MANUFACTURERS
By-Products Management Inc., 5220 East Avenue, Countryside, IL 60525
A-19
-------
FERROUS SULFATE
TRADE NAMES
Green vitriol, copperas, iron sulfate
AVAILABLE FORMS
Bags - 50, 100 Ib.
Bbls - 400 Ib.
Bulk - Carloads and truckloads
STORAGE
Oxidizes in moist air, cakes in
storage at temperatures above 68°F.
APPROX. 1979 COST
$80/ton
USES
Odor control, precipitate P04,
coagulation at pH 8.8-9.2, sludge
conditioning
COMMERCIAL STRENGTH
55-58% Fe S04 (20-2 IX Fe) .
FEEDERS
Gravimetric - L-I-W
Volumetric - helix (Fig. 9) , universal
(Fig. 7)
Solution - diaphragm or plunger
pump (Fig. 13)
SAFETY CONSIDERATIONS
Solution is acidic, mixing with
quicklime may cause fire, avoid body
contact
HANDLING MATERIALS
Asphalt,, concrete, lead, tin, wood, rubber, PVC, vinyl, Penton, epoxy,
Hypalon, ceramic, Tyril
Solutions - Lead, rubber, iron, plastics, 304SS
MAJOR MANUFACTURERS
Ashland Chemical Co., P.O. Box 2219, Columbus, Ohio 43216
By-Products Management Inc., 5200 East Ave., Countryside, IL 60525
American Cyanamid Co., Berdan Ave., Wayne, NJ 07410
National Lead, St. Louis, Missouri
Gulf Chemical, P.O. Box 2130, Hwy 519, Texas' City, Texas 77590
A-2Q
-------
HYDROCHLORIC ACID
•
TRADE NAMES
Muriatic acid
AVAILABLE FORMS
Glass bottles
Carboys
Drums
Tank cars
STORAGE
Store as received; highly corrosive
to metals. ,
APPROX. 1979 COST
$35 - $63/ton
USES
Neutralization of alkaline waste,
pH adjustment
COMMERCIAL STRENGTH
Concentrated: 37%- 38% HC1
18°Be - 27.9% HC1, 20°Be - 31.5%
22°Be - 35.2% HC1
HC1
FEEDERS
Solution - diaphragm pump (Fig.
13)
SAFETY CONSIDERATIONS
Fuming , pungent, toxic liquid;
avoid skin contact, use rubber
and safety glasses.
gloves
HANDLING MATERIALS
Penton, rubber, polyethylene, vinyl, Hypalon, Viton, Tyril .
MAJOR MANUFACTURERS
Allied Chemical Corp., Baton Rouge, LA; Danville, IL, Elizabeth, NJ;
Mounds ville, WV; Syracuse, NY
American Chemical Corp., Long Beach, CA .'..-•.
BASF Wyandotte Corp., Wyandotte, MI - ,
Continental Oil Co., Baltimore, MD
Dow Chemical USA, Freeport, TX; Midland, MI; Plaquemine, LA
E.I. du Pont Inc., LaPort, TX; Cleveland, OH; Linden, NJ
Hercules, Inc., Hopewell, VA; Parlin, NJ; Brunswick, GA
Monsanto Co., Everett, MAJ Sauget, IL
Pennwalt Corp, Calvert City, KY; Portland, OR; Tacoma, WA; Wyandotte, MI
Stauffer Chemical Co., Cold Creek, AL; Mt. Pleasant, TN; Dominguez, CA
A-21
-------
HYDROGEN PEROXIDE
TRADE NAMES
Hydrogen peroxide
AVAILABLE FORMS
Liquid
Drums - 50 gal. (minimum)
Tankcars
STORAGE
Bulk storage should be vented, with
tank constructed of 5254 aluminum
alloy. Decomposes rapidly if contam-
inated. Do not use stainless steel
except for very short term storage
(24 hrs) .
APPROX. 1979 COST
$0.16-$0.32/lb.
USES
Sulfide destruction, corrosion control,
control of bulking, supplemental D.O.
COMMERCIAL STRENGTH
35%, 50%, 70%
FEEDERS
Solution
Diaphragm or plunger pump (Fig. 13)
SAFETY CONSIDERATIONS
Prevent contact with most metals and
their salts, alcohols, acetone, organic
materials, aniline, nitrome thane,
flammable liquids, and combustible
materials. Dilute spills with water.
HANDLING MATERIALS
Polyethylene plastic, aluminum.
MAJOR MANUFACTURERS
Ashland Chemical Co., P.O. Box 2219, Columbus, Ohio 43218
FMC Corp., Industrial Chemical Div. , 2000 Market St., Philadelphia, PA 19103
A-22
-------
w
TRADE NAMES
( See calcium hydroxide and calcium
oxide)
: '
AVAILABLE FORMS
STORAGE
APPROX. 1979 COST
HANDLING MATERIALS
MAJOR MANUFACTURERS
t
\ - • -
Sr-2
USES
PnMMPDPIAl CTDC'M/2TU
irwiviivic.rtvsiMi_ o i rvdixu in , ....
FEEDERS
SAFETY CONSIDERATIONS
3
V I
-------
MAGNESIUM HYDROXIDE
TRADE NAMES
Magnesium hydroxide
AVAII ARI F POPUQ
MVMIl_HDl_C rV/r\MO
Wooden barrel or drums, glass bottles,
carboys
STORAGE
Absorbs CC>2 in presence of t^O
APPROX. 1979 COST
$0.54-$0.58/lb.
HANDLING MATERIALS
Steel, rubber, iron, Penton, Hypalon
MAJOR MANUFACTURERS
Basic Chemicals, 845 Hanna Bldg. , Clevc
;la
USES
Acid neutralization
S^f^MMPDfM Al OTmtKI/^TU
v/UMMtKt/IAL STRENGTH
Not applicable
FEEDERS
Gravimetric - L-I-W, belt (Fig. 10,11)
volumetric - helix (Fig. 9)
Slurry — diaphragm pump (Fig. 13)
SAFETY CONSIDERATIONS
No significant hazards
nd, OH 44115
A-24
-------
METHANOL
TRADE NAMES
Methanol
AVAILABLE FORMS
Tank Trucks
Tank cars
Drums
Bbls.
" Cans
STORAGE
Usually stored as received or in
conventional fuel tanks.
APPROX. 1979 COST
$0.56 - $0.63/gal.
USES
Denitrification
COMMERCIAL STRENGTH
99.9% CH3 OH
FEEDERS
Solution feed only
SAFETY CONSIDERATIONS
Vapors and liquid toxic and flammable.
Skin irritant. Liquid is colorless,
and noncorrpsive except to aluminum
and lead. Poisonous.
HANDLING MATERIALS
Steel
MAJOR MANUFACTURERS
E.I. du Pont de Nemours & Co., Beaumont, Tx; Orange, Tx.
Monsanto Co., Texas City, Tx.; plus others
Hercules, Inc., Plaquemine, La.
Air Products & Chemicals, Inc., Pensacola, Fla.
Tenneco Inc., Houston, Tx.
A-25
-------
OXYGEN (LIQUID)
TRADE NAMES
Oxygen
AVAILABLE FORMS
Cylinders
Tank cars
Gas bottles
Can also be generated on-site.
STORAGE
Cylinders or spheres of double-walled
construction, outer shell of carbon
steel, inner pressure vessel of
aluminum, SS, high nickel steel.
APPROX. 1979 COST
$35-$40/ton
USES
Odor control, oxidizing agent,
ammonia and BOD removal
COMMERCIAL STRENGTH
99.0-99.99%
FEEDERS
Liquid is vaporized and fed as a gas.
SAFETY CONSIDERATIONS
Colorless, odorless, tasteless gas.
Hazardous in contact with oxidizable
materials. Do not smoke near any
oxygen source.
HANDLING MATERIALS
Cast iron, stainless steel, bronze, monel
MAJOR MANUFACTURERS
Air Product & Chemicals, Inc., Box 538, Allentown, PA 18105
Air Co. Inc., Albany, NY; Huron, Ohio; New Orleans, La; Richmond, Cal;
Vancouver, Wash; plus others.
Chemetron Corp., Bartonville, 111; Chattanooga, Tenn; Richmond, Va;
Oklahoma City, Okla; plus others.
Union Carbide Corp., Cape Kennedy, Fla.; E. Chicago, Ind.; Fontana, Calif.;
Huntsville, Ala.; Kansas City, Mo.; Keasbey, NJ; plus others.
A-26
-------
OZONE
TRADE NAMES
Ozone
USES
Taste and odor control, disinfection,
oxidizing agent
AVAILABLE FORMS
Generated on-site by electrical
discharge through dry air
COMMERCIAL STRENGTH
1-2%
STORAGE
None,
Generated on-site
FEEDERS
Ozonator (Fig, 17)
APPROX. 1979 COST
Generated on-site
SAFETY CONSIDERATIONS
Toxic - do not breathe, explosive; fire
hazard; keep from oil or readily
combustible materials
HANDLING MATERIALS
Glass, 316SS, ceramic, aluminum, Teflon
MAJOR MANUFACTURERS
Purification Sciences Inc., P.O. Box 311, Geneva, NY 14456
A-27
-------
POLYMER
TRADE NAMES
Cat-floe, Drewfloc, Hereofloc,
Aquafloc, Superfloc, Magnifloc,
Purifloc
USES
Coagulant, filter aid, separates oily
wastes, removes SS, sludge condition-
ing, sludge dewatering aid
AVAILABLE FORMS
Available in many container and
package sizes — check with
manufacturer.
COMMERCIAL STRENGTH
Check with manufacturer.
STORAGE
Store in-dry, cool, low humidity area,
Use bags in proper rotation. Store
solutions 1 to 3 days or less to
prevent deterioration.
FEEDERS
Dry - See Figures 19 and 20
Solution - metering pump, rotodip
APPROX. 8979 COST
$0.60-$2.00/lb.
SAFETY CONSIDERATIONS
Polymer spills are slippery, clean up
promptly. Polymers are generally low
in toxicity and are nonirritating.
Check with manufacturer for other
safety information.
HANDLING MATERIALS
Depends on polymer type; however, 316SS, plastics generally are acceptable.
MAJOR MANUFACTURERS
Calgon Corp., P.O. Box 1346, Pittsburgh, PA 15230
Petrolite Corp., Tretolite Div., 369 Marshall Ave., St. Louis,MO 63119
American Cyanamid, Wayne, NJ 07470
Hercules Inc., Industrial Systems Dept., Wilmington, DE 19899
Philadelphia Quarts Systems Co., Inc., P.O. Box 840, Valley Forge, PA 19482
Rohm & Haas Co., Independence Mall West, Philadelphia, PA 19105
Drew Chemical Corp., 701 Jefferson Rd., Parsippany, NJ 07054
Dow- Chemical Co., Midland, MD 48640
Zimmlte Corp., 810 Sharon Dr., Cleveland, OH 44145
Garratt-Callahan Co., Ill Rollins Rd., Millbrae, CA 94030
Dearborn Chemical Div., Chemed Corp., 300 Genessee St., Lake Zurich, IL 60047
A-28
-------
POTASS IWERHANGANATE
TRADE NAMES
Cairox, purple salt
USES
Taste and odor control, removes Fe, Mn,
and Phenol, source of oxygen
AVAILABLE FORMS
USP
Steel Kegs - 25, 110, 125-Ibs
Tech
Steel drums - 25, 110, 600 Ibs
COMMERCIAL STRENGTH
Tech - 97% minimum
Reagent - 99% minimum
STORAGE
Can cake in high humidity, strong
oxidant
FEEDERS
Gravimetric - L-I-W
Volumetric - helix (Fig. 9)
Solution - diaphragm or plunger pump
(Fig, 13)
APPROX. 1979 COST
$1.29-$1.66/lb
SAFETY CONSIDERATIONS
Toxic, keep from organics, glycerine,
ethylene glycol, benzaldehyde, and
sulfuric acid
HANDLING MATERIALS
Steel, iron, PVC, 316SS, synthetic resins, Hypalon, Penton, Lucite, rubber
MAJOR MANUFACTURERS
Ashland Chemical Co., P.O. Box 2219, Columbus, Ohio 43216
Carus Chemical Co., 1500 8th St., La Salle, IL 61301
International Chemicals, Inc. 209 W. Central St., Natick, MA 01760
A-29
(J
-------
SODA ASH
TRADE NAMES
See sodium carbonate
AVAILABLE FORMS
STORAGE
APPROX. 1979 COST
USES
COMMERCIAL STRENGTH
FEEDERS
SAFETY CONSIDERATIONS
HANDLING MATERIALS
MAJOR MANUFACTURERS
A-30
-------
SODIUM ALUMINATE
TRADE NAMES
Soda alum
AVAILABLE FORMS
Dry
Bags - (ground) - 50, iCiO, 150 Ib.
Liquid
Drums - 380. Ib. ( 30 gaL)
Bulk .- tank car, tank truck
STORAGE
Dry_ - Store as received for 6 month
maximum at 60-90°F. Deteriorates on
exposure to atmosphere. Hopper
agitation may be required.
Liquid - Store as received for 2-3
months maximum. r
APPROX. 1979 COST
USES
Coagulation, phosphorus removal
COMMERCIAL STRENGTH
Dry - 41-46% Al2C-3
Liquid - 4.9 - 26.7% A1203
FEEDERS
Gravimetric - belt (Fig. 10,11), L-I-W
Volumetric - helix (Fig. 9),
universal (Fig. 7)
Solution - rotodip, 'diaphragm pump or
plunger pump (Fig. 13)
SAFETY CONSIDERATIONS
Exotheric heat of solution. Dust or
solution spray" should not be breathed.
Safety measures similar to caustic soda,
Avoid contact with eyes, skin and
clothing.
HANDLING MATERIALS
Iron, plastic, 316SS, 304SS," Penton, concrete, Hypalon
Avoid the use of copper, copper alloys, rubber, aluminum.
MAJOR MANUFACTURERS
Nalco Chemical Co., 2901 Butterfield Road, Oak Brook, IL
Reynolds Chemical Co., Bauxite, Arkansas
Vinings Chemical Co., Vinings, Georgia -
Conservation Chemical Co., Kansas City, Missouri
60521
A-31
-------
SODIUM BICARBONATE
TRADE NAMES
Baking soda
USES
pH adjustment, acid neutralization
AVAILABLE FORMS
:s_ - 100 Ib.
Drums - 25 Ib. kegs
Bbls - 112, 400 Ib.
Bulk - carloads
COMMERCIAL STRENGTH
99% NaHC03
STORAGE
Unstable in solution, (decomposes
into (X>2 & Na2 003) Decomposes at
100°F
FEEDERS
Gravimetric - belt (Fig. 10,11), L-I-W
Volumetric - helix (Fig. 9)
Solution - rotodip, diaphragm pump
(Fig. 13
APPROX. 1979 COST
$11 - $12/100 Ib.
SAFETY CONSIDERATIONS
No significant hazards
HANDLING MATERIALS
Iron, steel, rubber, saran, Hypalon, Tyril
MAJOR MANUFACTURERS
Church & Dwight Co., Inc., Two Pennsylvania Plaza, New York, New York 10001
BASF Wyandotte Corp., Wyandotte, Michigan 48192
A-32
-------
SODIUM BISULFITE
TRADE NAMES
Sodium metabifulfite, sodium
pyrosulfite, ABS . .. . -
USES
Dechlorination, reducing agent in
chromium treatment, pH control,
;bacteriocide
AVAILABLE FORMS
Bags - 100 Ib.
Drums - 100, 400 Ib.
COMMERCIAL STRENGTH
93-99% Na2S205
62-65.8% S02
STORAGE
Store cool and dry in tight container
(up to 6 mo.), vent solution tanks
(storage difficult)
FEEDERS
Gravimetric - L-I-W
Volumetric - helix (Fig. 9), universal
-(Fig. 7)
Solution - rotpdip, plunger or
diaphragm pump (Fig. 13)
APPROX. 1979 COST
$16 - $18/100 Ib.
SAFETY CONSIDERATIONS
Irritating to eyes, skin and
respiratory, system. Use protective
clothing and devices.'
HANDLING MATERIALS
Ceramic, chrome, glass, lead, 316SS, nickel, rubber, PVC, Pen ton, Tyril,
Hypalon, synthetic resin >:...-
MAJOR MANUFACTURERS
Ashland Chemical Co.. , P.'O. Box 2219,. Columbus, Ohio 43216
Virginia Chemicals, Inc., 3340 W. Norfolk Road, /Portsmouth, Virginia 23703
Allied Chemical Co., P.O. Box 1139R, Morristown, New Jersey 07960
A-33
-------
SODIUM CARBONATE
TRADE NAMES
Soda ash
USES
pH adjustment, acid neutralization
AVAILABLE FORMS
Bags - 100 Ib.
Bbls - 100 Ib.
Drums - 25, 100 Ib.
Bulk - carloads, box car, truck
COMMERCIAL STRENGTH
98-99% Na2C03, 58% Na20
STORAGE
Store in steel bins with dust
collectors. In bulk and bagged form,
absorbs C02 and t^O. "May cake in
storage.
FEEDERS
Gravimetric - L-I-W, belt (Fig. 10, 11)
Volumetric - helix, (Fig. 9)
Solution - rotodip, diaphragm or
plunger pump (Fig. 13)
APPROX. 1979 COST
$57-$87/ton
SAFETY CONSIDERATIONS
Dust and solution are irritating to
eyes, nose, lungs and skin
HANDLING MATERIALS
Iron, steel, rubber, Hypalon, Tyril
MAJOR MANUFACTURERS
Allied Chemical, P.O. Box 1139R, Morristown, New Jersey 07960
Dixie Chemical Co., 3635 W. Dallas Street, Houston, Texas 77019
PPG Industries, Inc., Chemical Div. , One Gateway Center, Pittsburgh, PA
FMC Corporation, Green River, Wyoming
Stauffer Chemical, Westend, California
Wyandotte Chemicals Corp., Wyandotte, Michigan 48192
15222
-------
SODIUFI HYDROXIDE
TRADE NAMES
Caustic soda, Soda lye
USES
pH control, filter cleaning,
neutralization
Bags - . 100 lb-. . :
Drums - 25, 50, 350, 400,700 lb.
Bulk -
AVAILABLE FORMS
Truckloads - 1,000 to 4,000 gal.
Carloads - 8,000, 10,000, 16,000 gaL
COMMERCIAL STRENGTH
Solid - 99.9% NaOH, 74-76% Na20
Solution - 50, 73% NaOH
STORAGE
Often stored at 20% concentration.
Crystallizes at 53°F for 50%
concentration, and 165°F for 73%
solution.
FEEDERS
Solution - plunger or
diaphragm pump (Fig. 13), rotodip
APPROX. 1979 COST
Liquid - $140-$175/ton
Solid - $350/ton
SAFETY CONSIDERATIONS
Caustic poison, dangerous to handle.
Prevent all body contact and protect
eyes.
HANDLING MATERIALS
Cast iron, rubber, steel, Penton, PVC, 316SS, Hypalon, nickel
MAJOR MANUFACTURERS
Allied Chemical Corp., P.O." Box 1139R, Morristown, New Jersey 07960
Ashland Chemical Co., P.O. Box 2219, Columbus, Ohio 43216
PPG Industries, Inc., Chemical Div., One Gateway Center, Pittsburgh, PA 15222
Dow Chemical, 2020 Dow Center, Midland, Michigan 48640
A-35
-------
SODIUM HYPOCHLORITE
TRADE NAMES
Javelle water, chlorine bleach
USES
Disinfection, slime control, odor
control, cyanide distribution
AVAILABLE FORMS
iarboys - 5, 13 gal.
Drums - 30 gal.
Bulk - 1,300, 1,800, 2,000 gal tank
trucks
COMMERCIAL STRENGTH
12-15% Available Clo
STORAGE
Store in cool place, away from light
and vent containers at intervals.
Can be stored about 60 days.
FEEDERS
Solution - diaphragm pump (Fig. 13 )
rotodip
APPROX. 1979 COST
$0.40 - $0.90/gal
depending on quantity
SAFETY CONSIDERATIONS
Corrosive. Avoid eye -and skin contact;
use protective clothing and devices.
HANDLING MATERIALS
Rubber, ceramic, glass, Tyril, saran, PVC, vinyl, Hypalon, plastic
MAJOR MANUFACTURERS
Brenco Corp., 704 N. First Street, St. Louis, Missouri 63102
Ashland Chemical Co., P.O. Box 2219, Columbus, Ohio 43216
Dixie Chemical Co., 3635 W. Dallas Street, Houston, Texas 77019
A-36
-------
SODIUM METABISULFITE
TRADE NAMES
See Sodium Bisulfite
-
A\/AII A Qt IT ftf*\mAC* " "'
AVAILABLE FORMS
STORAGE
... _ t, . .
.™ ...... , ,„.. . : _ ......
APPROX. 1979 COST
HANDLING MATERIALS
,,.,,.
MAJOR MANUFACTURERS
USES
•••••> •-.. - -• - * -. — .-, :,'.,,.. . _ .. .; ... .--......
PnMMtTD^IAI C-TDCTKI /2 TLJ
v/UmMtK ulAL OIKcNuIrl
FEEDERS
-
SAFETY CONSIDERATIONS
" ' ' ' *
A-37
-------
SODIUM SULFITE
TRADE NAMES
Sulfite
AVAILABLE FORMS
Bags, Bbls, Drums, Kegs
STORAGE
Store as received in cool, dry,
well-ventilated area
APPROX. 1979 COST
$0.04-$0.14/lb.
USES
Dechloririation, reducing agent
COMMERCIAL STRENGTH
93-99%
FEEDERS
Solution - plunger or
diaphragm pump (Fig. 13 ), rotodip
/
SAFETY CONSIDERATIONS
Solution gives off S02. Avoid eye
contact and prolonged or repeated
skin contact. Use protective clothing
and devices.
HANDLING MATERIALS
Cast iron, steel, 316SS, PVC, saran, vinyl, synthetic resin, Hypalon, Tyril
MAJOR MANUFACTURERS
Ashland Chemical Co., P.O. Box 2219, Columbus, Ohio 43216
A-38
-------
SODIUIiTHIOSULFATE
TRADE NAMES
Hypo, sodium hyposulfite
AVAILABLE FORMS
Bags, Bbls, Drums, Kegs
STORAGE
Store in cool, dry place
APPROX. 1979 COST
$12 - $17/100 lib.
USES
Dechlorination, reducing agent for
COMMERCIAL STRENGTH
98-99%
FEEDERS
Solution - plunger or
diaphragm pump (Fig. 13), rotodip
SAFETY CONSIDERATIONS
Avoid eye and skin'contact.
Use dust mask for excessive handling.
HANDLING MATERIALS
Cast iron, steel, stoneware-:
For no contamination: 316SS, PVC, saran, vinyl, synthetic resin, Hypalon, Tyril.
MAJOR MANUFACTURERS
Allied Chemical Corporation, N. Claymont, Del; Chicago, 111.,* El Segundo, Calif.
Stauffer Chemical Company, South Gate, Calif.
Ashland Chemical Company, P.O. Box 2219, Columbus, Ohio 43216
A-39
-------
SULFUR DIOXIDE
TRADE NAMES
Sulfur dioxide
AVAILABLE FORMS
Cylinders - 100, 150, 200 Ib,
Bulk - tanks
STORAGE
Pressure cylinders
APPROX. 1979 COST
$168 - $210/ton
USES
Dechlorination, filter cleaning,
Cr+6 reduction, pH control,
bacteriocide
COMMERCIAL STRENGTH
100% S02
FEEDERS
Gas - Rotameter , S02 feeder
SAFETY CONSIDERATIONS
Colorless, suffocating odor, corrosive,
-poisonous
HANDLING MATERIALS
Glass, PVC, ceramic,
Penton, Viton, Hypalon
MAJOR MANUFACTURERS
Cities Service Co.,
Virginia Chemicals,
3445 Peachtree Road, Atlanta, Georgia 30326
Inc., 3340 W. Norfolk Road, Portsmouth, Virginia 23703
A~40
-------
SULFURIC ACID
TRADE NAMES
Vitriol, oil of vitriol
-
AVAILABLE FORMS r«
Bottles . " ':v- " :
Carboys - 5,: 13 gal.
Drums - 55,110 gal .
Bulk - tankcars, trucks
'•
s ;...*-" "
STORAGE
Very corrosive, store dry. and cool in
tight containers
a : : ::.:•• ' ' •. '"
APPROX. 1979 COST
$30 - $61/ton
depending on quantity and strength.
USES
pH adjustment, neutralize alkaline
wastes
COMMERCIAL STRENGTH
66°Be - 93.2% H2S04
60°Be - 77.7% H7SOA
50°Be - 62.2% H0SO/.
FEEDERS
Liquid - plunger pr
diaphragm pump (Fig t 13^, rotodip
SAFETY CONSIDERATIONS
Always add acid to water, never add
water to acid. Avoid , contact with
potassium chlorate, potassium
perchlorate, potassium permanganate, &
other light metals: sodium & lithium
HANDLING MATERIALS
Concentrated - iron, steel, PVC, Penton, Viton
Dilute - Glass, lead, porcelain, rubber
MAJOR MANUFACTURERS
Allied Chemical Corp., P.O. Box 1139R, Morristown New Jersey 07960
Cities Services Co., 3445 Peachtree Road, Atlanta, Georgia 30302
American Cyanamid Co., Hamilton, Ohio; Joliet, Ill.j Kalamazoo, Mi; Savannah, Ga;
plus others
Bethlehem Steel Corp., Sparrows Pt., Md.
E.I. du Pont Nemours & Co. , Burnside, La; Newport, Ind; Richmond, Va; Wurtland,
Ky; Linden, NJ; plus others
Monsanto Co., El Dorado, Ark; Avon. Calif; Everett, Mass.
Rohm & Haas Company, Philadelphia, Pa; Deer Park, Tx.
A—41 * U. S. GOVERNMENT, PRINTING OFFICE - 1981 - 777-000/1108 Reg. 8
-------
-------
-------
Postage and
Fees paid
Environmental
Protection
Agency
EPA 335
Fourth-Class
United States
Environmental Protection
Agency
Washington DC 20460
Official Business
Penalty for Private Use $300
------- -------
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