EPA-600/2-78-043a
March 1978
Environmental Protection Technology Series
PRETREATMENT OF THE COMBINED
INDUSTRIAL-DOMESTIC WASTEWATERS OF
HAGERSTOWN, MARYLAND
Volume I
Rot
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-78-043 a
February 1978
PRETREATMENT OF THE COMBINED INDUSTRIAL-DOMESTIC
WASTEWATERS OF HAGERSTOWN, MARYLAND
Volume I
by
David S. Kappe
Kappe-Associates, Inc.
Hagerstown, Maryland 21740
Project No. 11060 EJD
Project Officers
Harold J. Snyder, Jr.
Marshall Dick
Office of Research and Monitoring
U.S. Environmental Protection Agency
Washington, D.C. 20460
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
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DISCLAIMER
This report has been reviewed by the Robert S. Kerr Environmental
Research Laboratory, U.S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily re-
flect the views and policies of the U.S. Environmental Protection Agency,
nor does mention of trade names or commercial products constitute endorse-
ment or recommendation for use.
ii
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FOREWORD
The Environmental Protection Agency was established to coordinate
administration of the major Federal programs designed to protect the
quality of our environment.
An important part of the Agency's endeavors to fulfill its mission
involves the search for information about environmental problems, manage-
ment techniques and new technologies through which optimum use of the
nation's land and water resources can be assured. The primary and ulti-
mate goal of these efforts is to protect the nation from the scourge of
existing and potential pollution from all sources.
EPA's Office of Research and Development conducts this search through
a nationwide network of research facilities.
As one of these facilities, the Robert S. Kerr Environmental Research
Laboratory is responsible for the management of programs to: (a) investi-
gate the nature, transport, fate and management of pollutants in ground-
water; (b) develop and demonstrate methods for treating wastewaters with
soil and other natural systems; (c) develop and demonstrate pollution con-
trol technologies for irrigation return flows; (d) develop and demonstrate
pollution control technologies for animal production wastes; (e) develop
and demonstrate technologies to prevent, control or abate pollution from
the petroleum refining and petrochemical industries; and (f) develop and
demonstrate technologies to manage pollution resulting from combinations
of industrial wastewaters or industrial/municipal wastewaters.
This report is a contribution to the Agency's overall effort in ful-
filling its mission to improve and protect the nation's environment for
the benefit of the American public.
William C. Galegar, Director
Robert S. Kerr Environmental
Research Laboratory
iii
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ABSTRACT
The sewage treatment plant of the city of Hagerstown, Maryland—a
manufacturing city with about 130 industrial firms, which are classified
in more than 25 different product categories—receives for treatment
domestic sewage and a diversity of industrial waste and process waters.
Some of these industrial wastewaters exert high immediate and ultimate
oxygen demands that could not be satisfied by the treatment plant or
were otherwise detrimental to the biological treatment processes of the
treatment system. Therefore, certain methods of "pretreating" the city's
combined wastewaters to render these waters, more amenable to treatment
by the existing treatment plant were tried and evaluated. The pretreat-
ment methods tested were intended to assist the plant in meeting the
oxygen demands by providing initial oxidation. The methods were: diffuse
aeration with and without the addition of waste activated sludge,
chlorination, addition of sodium nitrate, and the addition of potassium
permanganate. Ammoniation was also tried in an effort to destroy some
of the more noxious industrial materials in the wastewaters. Both
aeration and chlorination proved to be effective methods of pretreatment,
with the efficacy of aeration being enhanced somewhat by the addition of
waste activated sludges. Both methods increased the BODg removal
efficiency of the plant under dry-weather conditions from less than 70%
to better than 90%.
IV
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TABLE OF CONTENTS
Page
Abstract iii
List of Tables vii
List of Figures xiv
Acknowledgments xv
Sections
I. Introduction 1
A. Statement of the Problems and Objectives of Study 1
B. General Study Plan 3
II. Conclusions 8
III. Recommendations 10
IV. The Project Site—The Hagerstown Water Pollution
Control Plant—and the Project Facility 11
A. Description of the Hagerstown Water Pollution
Control Plant 11
B. Capacities of Existing Sewage Treatment Units 15
C. Project Modifications of the Hagerstown Water
Pollution Control Plant 17
D. Project Facility 18
V. Baseline Studies 27
A. Preliminary Wastewater Analyses 27
B. Survey of Industrial Plant 38
VI. Studies of Various Pretreatment Methods 69
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TABLE OF CONTENTS (continued)
A. Wastewater Analysis Schedule for Pretreatment
Studies 69
B. Startup and Stabilization of the Project Facility 69
C. Pretreatment by Plain Aeration and by Aeration
and the Addition of Waste Activated Sludge 76
D. Pretreatment by Addition of Sodium Nitrate and
by Addition of Ammonia 82
E. Pretreatment by Addition of Potassium Perman-
ganate and by Addition of Chlorine 87
F. Pretreatment by Addition of Potassium Perman-
ganate 88
6. Pretreatment by the Select Method 91
H. Sludge Dewatering Experiments 93
VII. Summary 96
A. General 96
B. Subsequent Work 97
VIII. Reference 99
IX. Appendices (Available only from NTIS)
vt
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TABLES
No. Page
1. Chemicals and Dyestuffs Consumed by the Florida 44
Avenue Plant of the Potomac Dye and Printing
Corporation
2. Chemicals and Dyestuffs Consumed by the Franklin 48
Street Plant of the Potojnac Dye and Printing
Corporation
3. Chemicals and Dyes Used by the Associated Ribbon 53
Works
4. Chemicals Used by Victor Hosiery Company 58
5. Daily Chemical Useage of the Maryland Ribbon Conjpany 60
6. Chemical and Materials Used by the W. H. Reisner 62
Manufacturing Company
7. Chemicals and Other Substances Used in Processes 66
of the Breakstone Foods Plant
8. Analysis Schedule for the Operational Studies 70
9. Description of Sampling Points 74
10. Average Percent Removals of 6005, COD and Suspended 90
Solids Achieved for the Four Two-Week Periods of
the Study of Pretreatment by Chiorination
11. The Decrease With Time in the Percent Moisture 95
Content of Digested Sludge Placed on Sand Drying
Beds in Various Layer Thicknesses
12. Wastewater Flows and Temperatures Pretreatment by 112
Aeration and Sludge Addition and Plain Aeration
Treatment Systems A and B
13. BODc Values of 24-Hour Composite Wastewater Samples 118
Pretreatment by Aeration and Addition of Waste
Activated Sludge Treatment System A
vfi
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TABLES (continued)
No._
14 COD Values of 24-Hour Composite Wastewater Samples 121
Pretreatment by Aeration and Addition of Waste
Activated Sludge Treatment System A
15. Suspended Solids Levels in 24-Hour Composite 124
Wastewater Samples Pretreatment by Aeration
and Addition of Waste Activated Sludge Treat-
ment System A
16. Hydrogen Ion Concentrations in 24-Hour 130
Composite Wastewater Samples Pretreatment by
Aeration and Addition of Waste Activated
Sludge Treatment System A
17. Dissolved Oxygen Concentrations in Wastewaters 134
Pretreatment by Aeration and Addition of Waste
Activated Sludge Treatment System A
18. Hydrogen Sulfide Concentrations in Wastewaters 138
Pretreatment by Preaeration and Addition of
Waste Activated Sludges Treatment System A
19. Oxidation-Reduction Potentials of Wastewaters* 142
Pretreatment by Aeration and Addition of Waste
Activated Sludge Treatment System A
20. BOD5 Values of 24-Hour Composite Wastewater 143
Samples Pretreatment by Plain Aeration Treatment
System B
21. COD Values of 24-Hour Composite Wastewaters 146
Samples Pretreatment Plain Aeration Treatment
System B
22. Suspended Solids Levels in 24-Hour Composite 149
Wastewater Samples Pretreatment by Plain Aeration
Treatment System B
23. Hydrogen Ion Concentrations in 24-Hour Composite 154
Wastewater Samples Pretreatment by Plain Aeration
Treatment System B
24. Dissolved Oxygen Concentrations in Wastewaters 158
Pretreatment by Plain Aeration Treatment System B
25. Hydrogen Sulfide Concentrations in Wastewaters 161
Pretreatment by Plain Aeration Treatment System B
vm
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TABLES (continued)
No. Page
26. Oxidation-Reduction Potentials of Wastewaters* 165
Pretreatment by Plain Aeration Treatment System B
27. Wastewater Flows and Temperatures Pretreatment by 167
Addition of Sodium Nitrate and by Addition of
Ammonia Treatment Systems A and B
28. BOD5 Values of 24-Hour Composite Wastewater 172
Samples Pretreatment by Addition of Sodium
Nitrate Treatment System A
29. COD Values of 24-Hour Composite Wastewater Samples 175
Pretreatment by Addition of Sodium Nitrate Treat-
ment System A
30. Suspended Solids Levels in 24-Hour Composite 178
Wastewater Samples Pretreatment by the Addition
(of Sodium Nitrate Treatment System A
31. Organic Nitrogen Concentrations in 24-Hour 183
Composite Wastewater Samples Pretreatment by
Addition of Sodium Nitrate Treatment System A
32. Ammonia Nitrogen Concentrations in 24-Hour Com- 185
posite Wastewater Samples Pretreatment by Addition
of Sodium Nitrate Treatment System A
33. Nitrite Nitrogen Concentrations in 24-Hour Com- 187
posite Wastewater Samples Pretreatment by Addition
of Sodium Nitrate Treatment System A
34. Nitrite Plus Nitrate Nitrogen Concentrations in 190
24-Hour Composite Wastewater Samples Pretreatment
by Addition of Sodium Nitrates Treatment System A
35. Dissolved Oxygen Concentrations in Wastewaters 193
Pretreatment by Addition of Sodium Nitrate
Treatment System A
36. Hydrogen Sulfide Concentrations in Wastewaters 196
Pretreatment by Addition of Sodium Nitrate
Treatment System A
37. Hydrogen Ion Concentrations in 24-Hour Composite 199
Wastewater Samples Pretreatment by Addition of
Sodium Nitrate Treatment System A
IX
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TABLES (continued)
No. Page
38. 8005 Values of 24-Hour Composite Wastewater 203
Samples Pretreatment by Addition of Ammonia
Treatment System B
39. COD Values of 24-Hour Composite Wastewater 206
Samples Pretreatment by the Addition of Ammonia
Treatment System B
40. Suspended Solids Levels in 24-Hour Composite 210
Wastewater Samples Pretreatment by the Addition
of Ammonia Treatment System B
41. Organic Nitrogen Concentrations in 24-Hour Waste- 215
water Samples Pretreatment by Addition of Ammonia
Treatment System B
42. Ammonia Nitrogen Concentrations in 24-Hour 217
Composite Wastewater Samples Pretreatment by
Addition of Ammonia Treatment System B
43. Nitrite Nitrogen Concentrations in 24-Hour 219
Composite Wastewater Samples Pretreatment by
the Addition of Ammonia Treatment System B
44. Nitrite Plus Nitrate Nitrogen Concentrations 221
in 24-Hour Composite Samples Pretreatment by
Addition of Ammonia Treatment System B
45. Dissolved Oxygen Concentrations in Wastewaters 223
Pretreatment by Addition of Ammonia Treatment
System B
46. Hydrogen Sulfide Concentrations in Wastewaters 226
Pretreatment by Addition of Ammonia Treatment
System B
47. Hydrogen Ion Concentrations in 24-Hour Composite 229
Wastewater Samples Pretreatment by Addition of
Ammonia Treatment System B
48. Wastewater Flows and Temperatures Pretreatment 233
by Addition of Chlorine and by Addition of
Potassium Permanganate Treatment Systems A and B
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TABLES (continued)
No. Page
49. BODs Values of 24-Hour Composite Wastewater 238
Samples Pretreatment by Addition of Potassium
Permanganate Treatment System A
50. COD Values of 24-Hour Composite Wastewater 241
Samples Pretreatment by Addition of Potassium
Permanganate Treatment System A
51. Suspended Solids Levels in 24-Hour Composite 244
Wastewater Samples Pretreatment by the Addition
of Potassium Permanganate Treatment System A
52. Organic Nitrogen Concentrations in 24-Hour 248
Composite Wastewater Samples Pretreatment by
Addition of Potassium Permanganate Treatment
System A
53. Ammonia Nitrogen Concentrations in 24-Hour 250
Composite Wastewater Samples Pretreatment by
Addition of Potassium Permanganate Treatment
System A
54. Nitrite Nitrogen Concentrations in 24-Hour 252
Composite Wastewater Samples Pretreatment by
Addition of Potassium Permanganate Treatment
System A
55. Nitrite Plus Nitrate Nitrogen Concentrations in 254
24-Hour Composite Wastewater Samples Pretreat-
ment by Addition of Potassium Permanganate
Treatment System A
56. Dissolved Oxygen Concentrations in Wastewaters 256
Pretreatment by Addition of Potassium Perman-
ganate Treatment System A
57. Hydrogen Ion Concentrations in 24-Hour Composite 259
Wastewater Systems Pretreatment by Addition of
Potassium Permanganate Treatment System A
58. Manganese Concentration in Grab Samples Pretreat- 263
ment by Addition of Potassium Permanganate
Treatment System A
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TABLES (continued)
No.
59. BODs Values of 24-Hour Composite Samples of 264
Treatment Plant Influent and Effluent Pre-
treatment by Chiorination Treatment System B
60. COD Values of 24-Hour Composite Wastewater 267
Samples Pretreatment by Addition of Chlorine
Treatment System B
61. Suspended Solids Levels in 24-Hour Composite 270
Wastewater Samples Pretreatment by the Addition
of Chlorine Treatment System B
62. Organic Nitrogen Concentrations in 24-Hour 275
Composite Wastewater Samples Pretreatment by
Addition of Chlorine Treatment System B
63. Ammonia Nitrogen Concentrations in 24-Hour 277
Composite Wastewater Samples Pretreatment by
Addition of Chlorine Treatment System B
64. Nitrite Nitrogen Concentrations in 24-Hour 279
Composite Wastewater Samples Pretreatment by
Addition of Chlorine Treatment System B
65. Nitrite Plus Nitrate Nitrogen Concentrations 281
in 24-Hour Composite Wastewater Samples Pre-
treatment by Addition of Chlorine Treatment
System B
66. Dissolved Oxygen Concentrations in Wastewaters 283
Pretreatment by Addition of Chlorine Treatment
System B
67. Hydrogen Ion Concentrations in 24-Hour Composite 286
Wastewater Samples Pretreatment by Addition of
Chlorine Treatment System B
68. Wastewater Flows and Temperatures Pretreatment 291
by Chiorination (300 Ibs Cl2/day) Combined
Treatment System
69. BODs Values of 24-Hour Composite Wastewater 293
Samples Pretreatment by Chiorination (300 Ibs
Cl2/day) Combined Treatment System
xn
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TABLES (continued)
No. Page
70. COD Values of 24-Hour Composite Wastewater 295
Samples Pretreatment by Chiorination
(300 Ibs Cl2/day) Combined Treatment System
71. Suspended Solids Levels in 24-Hour Composite 297
Wastewater Sample Pretreatment by Chiorination
(300 Ibs Cl2/day) Combined Treatment System
72. Total Chlorine Residuals in Wastewaters Pre- 301
treatment by Chiorination (300 Ibs Cl2/day)
Combined Treatment System
xiii
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FIGURES
No. Page
1. Schematic Diagram of the Hagerstown Water Pollution 19
Control Plant
2. A View of the Pretreatment Facility from the Head 24
End of the Pretreatment Tanks
3. A View across the Pretreatment Tanks of the Project 25
Facility, Showing the Primary Settling Tanks and
Other Parts of the Hagerstown Water Pollution Control
Plant in the Background
4. The Project Facility immediately prior to the Intro- 26
duction of the Municipal Wastewaters into the
Pretreatment Tanks
5. Oxygen Demand Indices (GDI's) of Grab Samples of 30
Primary Effluent Collected over the period of
October 18 to October 24, 1967
6. Photomicrograph of the Aeration Tank Mixed Liquors, 35
Taken during the Baseline Study and Showing Fila-
mentous Sulfur Bacteria Containing Globules of
Sulfur and Growing among Masses of Zoogleal Bacteria
7. Photomicrograph of the Aeration Tank Mixed Liquors, 75
Showing New Fingerlike Growths of Zoogleal Bacteria
8. Photomicrographs of the Aeration Tank Mixed Liquors, 78
Taken during the Study of Pretreatment by Addition of
Sodium Nitrate and Showing Unidentified Filamentous
Bacteria among Small Zoogleal Masses with much
Adsorbed Inert Solids and the General "Burnt-Out"
Appearance of Overage Sludge Resulting from Excessive
Recycling of Biological Solids in the Treatment Plant
xiv
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ACKNOWLEDGMENTS
This project was supported by the U. S. Environmental Protection Agency
through EPA Research, Development and Demonstration Grant No. 11060 EJD,
the State of Maryland and the City of Hagerstown, Maryland.
The Project Director wishes to express his deep appreciation to
Mr. Harold J. Snyder, Jr., who was the EPA Project Officer at the start
and through most of the project, for his much needed administrative
help and to Mr. Marshall Dick, who took over the duties of Project
Officer at the end of the project, for his patience and guidance in
the preparation of this report.
Also, special thanks are extended to the Honorable Herman L. Mills, who
was Mayor of the City of Hagerstown during the project and also the
Project Grant Administrator, for his sincere interest in and steadfast
support of the project program and the project team and to both
Mr. Robert E. Lakin, who, as President of J. B. Ferguson and Company,
had immediate responsibility for both the administrative and technical
aspects of the project, and Mr. Stanley E. Kappe, President of Kappe
Associates, Inc., for their invaluable guidance and engineering exper-
tise in the design and construction of research facility and in the
project studies.
Thanks are also due to Mr. James E. Eyerly, Superintendent of the
Hagerstown Water Pollution Control Plant during the project, for his help
in coordinating project activities at the project site and to his then
assistant and the present plant Superintendent Mr. Eugene Barnhart for
his outstanding assistance with the day-to-day operations and maintenance
of the pretreatment facility and with the on-site analytical program, and
to the laboratory technicians and plant operators of the Hagerstown treat-
ment plant for their fine efforts in carrying out the project program plan.
It is a pleasure to acknowledge, too, Dr. Charles E. Renn, Professor
Emeritus of Environmental Science Engineering, the Johns Hopkins
University and Research Associate of Kappe Associates, Inc., who
conducted the microscopic examinations of the plant biota, and
Mr. Dick C. Heil, Mr. Neil F. Kershaw and Mrs. Julia M. Patel,
engineer and chemists, respectively, of Kappe Associates, Inc.,
their exceptional engineering and analytical contributions to the
project.
In addition, the Project Director wishes to thank the industries that
were surveyed under the project for their superb cooperation and partici-
pation in the survey effort.
xv
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SECTION I
INTRODUCTION
A. Statement of the Problems and Objectives of Study
The City of Hagerstown, Maryland, with a population of over 35,000 persons,
is the seventh largest municipality in the state of Maryland. It is a
manufacturing city with about 130 industrial firms, which are classified
in more than 25 different product categories. These industries produce
such diverse products as aircraft, trucks, pipe organs, furniture, food
products, chemicals, dyed textiles, electrical equipment, tools and toys.
Thus, the Hagerstown Water Pollution Control Plant, which serves not only
the city proper but also contiguous areas, receives in addition to
domestic sewage a diversity of industrial waste and process waters.
Some of these waters exert high immediate and ultimate oxygen demands
that could not be satisfied by the existing treatment plant or were
otherwise detrimental to the biological treatment processes of the plant.
Consequently, the Hagerstown treatment plant experienced great difficulty
in achieving wastewater treatment to the degree necessary to meet the
requirements established by the Maryland Department of Health and the
Maryland Department of Water Resources. Although the plant uses the
contact stabilization form of the activated sludge process—which in
theory ought to be able to reduce the pollutional strength of the raw
wastewaters in terms of BOD by at least 85%--it typically achieved BODg
removals in the range of only 40 to 60 percent.
From time to time, over a period of many years, treatment plant personnel
and various consulting engineering firms called in by the city conducted
at best cursory investigations to ascertain the specific causes of the
Hagerstown wastewater treatment problems. Their findings strongly
suggested that the industrial wastewaters that were the most harmful to
the treatment plant were those from the metal plating plants and textile
dyeing plants. Moreover, most, if not all, of these investigators strongly
suspected that certain substances in these particular industrial waste-
waters exhibited inhibitory and even toxic effects on the biota of the
treatment plant. It was reported by one team of investigators who carried
out a fairly extensive survey of the industries "in the city that the
following noxious and toxic substances were being discharged into the
city's sanitary sewage system and reaching the treatment plant in
sufficient concentrations to be especially troublesome:
1. Napthols—water insoluble azo dyes, which act as strong dis-
infectants.
2. Sodium hydrogen sulfite—a strong reducing agent, which can
readily react with dissolved oxygen and therefore exert an
immediate oxygen demand. It is used in textile dyeing as
an antichlor, primarily.
1
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3. Sodium hydrosulfite (sodium dithionite)--a reducing agent that
is stronger than sodium hydrogen sulfite. It is used in textile
dyeing as a dye stripping agent and bleach.
4. Sulfonated organic compounds—dyes and detergents.
5. Sulfoxylates—-strong reducing agents, which like sodium
hydrosulfite are used as stripping agents in textile
dyeing.
6. Reduced chemical dyes—complex organic compounds that,
reportedly, are readily oxidized and require considerable
amounts of oxygen for treatment.
7. Chromate metallic dyes.
8. Petroleum solvents.
9. Miscellaneous chemicals—sulfuric acid, hydrochloric, acetic
acid and formaldehyde.
Daily tests taken by the laboratory personnel of the treatment plant had
indeed shown that "free sulfites", which ideally should not be present
at all in the raw wastewaters, entered the plant on week days in con-
centrations that generally ranged from 4 to 200 mg/1 and occasionally
reached as high as 450 mg/1. Sulfites were usually not found in the
wastewater on either Saturdays or Sundays; and, it was noted that the
variations of sulfite concentrations during week days followed no regular
pattern.
Although the plant consistently failed to produce an effluent of accept-
able quality, the most noticeable plant operational problem—which
subjected the city government, the city engineer and plant management
personnel to much public criticism—was the continual production by the
plant of offensive odors, in particular, the pungent, "rotten-egg" odor
of hydrogen sulfide gas. Frequently, the concentration of hydrosulfuric
acid, H2S, in the plant effluent would be found to be as high as 10 mg/1,
and hydrogen sulfide gas would emanate from the primary tanks and would
be swept from the aeration tanks in amounts sufficient to annoy the
entire population of the City of Hagerstown, as well as people of
surrounding communities.
As a result of a great public outcry, efforts were made by plant per-
sonnel to minimize the generation of this odoriferous gas'in the aeration
basins by maintaining mixed liquor suspended solids concentrations in the
contact aeration tanks at very low levels (500 to 900 mg MLSS/1) and to
check production of the gas by constant chlorination of the return sludges
and the mixed liquors themselves. Unfortunately, however, these efforts
were only partially successful in abating odors and, of course, did not
improve the wastewater treatment efficiency of the treatment plant.
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In another effort to minimize treatment plant problems, key officials of
the textile dyeing plants that discharged into the city's sewage system
were contacted by representatives of the city and meetings between the
city representatives and the dye plant officials were held to inform the
dye plants officials of the difficulties being experienced by the treat-
ment plant and to solicit their aid in abating the discharge of noxious
and toxic dyeing wastes into the city's sewers. Consequently, the dye
plants agreed to cooperate and to take certain corrective steps.
Unfortunately, however, no significant improvement in conditions at the
treatment plant was ever noted as a result of these meetings.
Also at these meetings, it was suggested that the dyeing plants should
treat their wastes before the wastes are discharged into the sewerage
system; but, it was quickly pointed out by the dye plant officials that
most of the dyeing plants are located well within the city and, have
limited, if any, space for expansion and that the possibility of them
constructing waste pretreatment systems therefore was rather small.
Consequently, in May 1967, the city formulated a research program to
study through a full-scale project various methods of actually pretreat-
ing the city's combined industrial-domestic wastewaters at the site of
the municipal treatment plant itself and, subsequently, applied to the
Federal government for financial assistance. In March 1968, the city
received from the Federal Water Pollution Control Administration a
Federal Research and Development Grant, WPRD 149-01-68, of $320,890 or
75% of eligible project costs, whichever was less. This grant was then
supplemented by a state grant covering 12.5% of project costs eligible
for coverage under the Federal grant. The project costs eligible for
Federal participation equalled the total project cost of $427,853.
B. General Study Plan
The object of the project was to study and evaluate certain pretreatment
methods aimed at rendering the city's combined industrial-domestic waste-
waters more amenable to the existing conventional biological treatment
processes of the city's wastewater treatment plant. Since the combined
wastewaters regularly exerted high immediate and ultimate oxygen demands,
five of the six pretreatment methods that were studied were methods in-
tended to assist the existing treatment plant in meeting these oxygen
demands by providing initial oxidation. The five pretreatment methods
were diffuse aeration with and without the addition of waste activated
sludge, chlorination, sodium nitrate addition, and potassium permanganate
addition. Ammoniation was the sixth pretreatment scheme that was studied.
It was hoped that ammonia would prove to be effective in destroying some
of the more noxious industrial materials contained in the wastewaters.
As planned, these pretreatment methods were studied in pairs to conserve
project time and were applied to the raw wastewaters as these wastewaters
flowed through a pretreatment facility built especially for the research
project on the grounds of the Hagerstown Water Pollution Control Plant.
This facility, which was designed to handle the city's entire wastewater
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flow, was constructed between the grit chamber and the primary settling
tanks of the municipal treatment plant. The facility consists of two^
aeration tanks, a mechanical building for housing the necessary facility
equipment and the facility equipment.
At the design flow for the treatment plant, the facility aeration tanks
each hold 300000 gallons (40000 ft3) of wastewater and together, a total of
600000 gallons (80000 ft3) of wastewater. Air can be supplied to the two
tanks by either or both of two positive displacement type blowers, each
having a capacity of 3500 cfm. These blowers are a part of the facility
equipment and were purchased with project funds. The aeration tanks with
their air supplies were intended not only for aerating the wastewaters as
called for in the project plan but also for mixing the wastewaters with
the selected chemical additives that were tested under the various study
tasks of the project.
Facility equipment also include a dry chemical feeder for feeding sodium
nitrate and potassium permanganate and a gas feeder for feeding ammonia
and chlorine. By means of a valve-and-piping system, these feed machines
were able to deliver aqueous solutions of the various chemical additives
used in the project to the influent ends of one or the other or to both
of the two aeration tanks of the facility.
Also among the equipment of the facility are an electronic wastewater
quality monitoring system that was able to measure and record continually
the pH, dissolved oxygen concentrations and oxidation-reduction potentials
of the raw wastewaters and of the effluents of the two aeration tanks and
three automated and refrigerated samplers that collected proportionally
to the flow composite samples of the raw wastewaters and the two aeration
tank effluents.
The pretreatment facility was constructed with two aeration tanks so that,
as mentioned, two pretreatment methods could be studied at the same time.
As the wastewater flow passed through the influent channel of the research
facility, it was divided into two separate flows for separate treatment.
Beyond the project facility, the treatment plant itself was modified as
called for under the research program, to enable this flow separation to
be maintained. Thus, the existing treatment plant beyond the facility
functioned essentially as two independent and distinct secondary treatment
systems, whose responses to the pretreatment methods being employed could
be examined. However, it should be noted that since two studies were
always conducted simultaneously with the plant divided, one plant division
never functioned as the experimental "control" for the other.
The original project program plan provided 4 months for the design of the
project facility, a month and a half for bidding and letting of the con-
struction contract and nine and one half months for facility construction.
In addition, nine months after the project was initiated and concurrent
with project facility construction, the program plan scheduled five months
for the acquisition of necessary laboratory equipment, training of
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laboratory personnel and establishment of analytical procedures. For a
three-month period starting twelve months after project initiation, the
plan called for extensive analyses of the wastewaters entering, passing
through and leaving the Hagerstown plant in order to gather good informa-
tion on wastewater characteristics and treatment plant performances.
Once the construction of the project facility was completed and the
baseline analyses were finished, the project plan called for the treatment
facility to be brought into service and tested and its aeration tanks
allowed to stabilize for one month. Then, the various pretreatment
methods were to be studied in pairs, each pair being tried over a two-
month period with two weeks allotted after each study (except the last,
of course) for the incoming raw sewage to pass through the pretreatment
tanks with only plain aeration to flush out the tanks for the next study
and to allow time for process "change over."
After the various pretreatment methods were tried and evaluated, that
method that yielded the best results then was to be studied further, for
an additional two months; but, this time, the study was to be done with
pretreatment method being applied to the entire wastewater flow and with
the secondary systems of the treatment plant recombined so that the plant
beyond the pretreatment facility would function as a single unit as it
had before the pretreatment studies were begun.
Also included in the project program plan was a survey of certain select
industries within the city—industries that were suspected of being possible
sources of the more noxious and toxic wastes that the treatment plant was
receiving. On the basis of the assumption that most of the noxious and
toxic wastes were contributed by the textile dyeing plants, these plants,
in particular, were considered of primary interest and, therefore, were
the main concern of the planned survey. This survey was scheduled to
begin one month after the start of the project and to end seven months
later.
Except for delays in construction of the project facility and in the con-
struction of an additional final settling tank for the treatment plant
and modification of two existing final settling tanks (work not done under
the program of the research project) and extensions of a pretreatment
study and the industrial survey periods, this project schedule and plan
was essentially adhered to. The project program tasks and the actual
periods over which they were carried out are as follows:
Period Project Task
5/22/68 - 10/1/68 Site studies and design of project
facility.
10/1/68 - 12/11/68 Review of facility plans and
specification by state and
federal agencies.
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Period
Project Task
12/23/68 - 1/30/69
8/1/68 - 9/31/70
10/1/68 - 7/15/69
7/15/69 - 5/19/70
1/27/70 - 5/19/70
5/19/70 - 7/24/70
7/24/70 -
8/18/70 -
10/15/70
10/31/70
8/18/70
10/15/70
- 10/31/70
- 12/25/70
12/25/70 - 1/18/71
1/18/71 - 3/23/71
Construction of project facility
and modification of treatment plant
piping to achieve two separate
secondary treatment systems.
Survey of industrial plants.
Preparation of treatment plant
laboratory for analytical program
of the project, training of
laboratory personnel, and establish-
ment of analytical procedures.
Execution of baseline studies--
analysis of treatment plant waste-
waters.
Startup of project facility,
stabilization of the aeration
tanks of the facility, and
installation and calibration
of the facility wastewater
quality monitoring system.
Investigation of wastewater pre-
treatment by plain aeration and by
aeration with addition of waste
activated sludge.
Preparation for the next pair of
pretreatment studies.
Investigation of wastewater pretreat-
ment by addition of ammonia and by
addition of sodium nitrate.
Preparation for next pair of pre-
treatment studies.
Investigation of wastewater pretreat-
ment by addition of chlorine and by
the addition of potassium permanganate.
Preparation for final pretreatment
studies—recombination of in-plant
wastewater flows.
Application of pretreatment by
chlorination, to entire raw waste-
water flow.
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Period Project Task
2/20/71 - 1/16/71 Loading of specially prepared digestor
with combined sludges and digestion of
sludges for sludge dewatering studies.
4/1/71 - 4/7/71 Studies on dewatering of digested
sludges and waste activated sludge
on a pilot vacuum filter.
4/15/71 - 4/21/71 Studies on dewatering of digested
sludges on an existing sand bed.
4/21/71 Supplementary analyses and data
tabulation.
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SECTION I I
CONCLUSIONS
From May 22, 1968, to April 21, 1971, the City of Hagerstown, Maryland,
investigated six proposed schemes of pretreating its combined domestic-
industrial wastewaters. These schemes or methods, which, during the
investigation, were applied to the city's raw wastewaters at the site of
the city's wastewater treatment plant, were pretreatment by plain aera-
tion, aeration with the addition of waste activated sludge, ammoniation,
chlorination, addition of potassium permanganate, and addition of sodium
nitrate. It was hoped that one or more of these methods would be effec-
tive in significantly increasing the rather poor degree of treatment the
existing plant was able to achieve and in eliminating the frequent
evolution from the plant of the malodorous gas hydrogen sulfide.
During the project, it was found that the plant suffered from (1) hydraulic
overloading during wet-weather conditions as a result of the considerable
susceptibility of the city's sanitary sewage system to stormwater inflow,
(2) organic overloading occurring regularly on week-day mornings as a
result of batch discharges of cottage cheese whey from a local food pro-
cessing plant and (3) the frequent presence in the raw wastewaters of
dye stripping agents (which exerted high immediate oxygen demands) and
intensely colored dye stuffs from local textile dyeing plants.
The hydraulic and organic overloads were overwhelming in their impacts
on the treatment plant and were obviously the major causes of the treat-
ment difficulties the facility was having. In addition, it is believed
that, because of their overwhelming nature, the two types of overloads
could have easily obscured other factors contributing to the poor treat-
ment performance of the plant. Moreover, they interfered greatly with
several of the pretreatment studies of the project, particularly the
hydraulic overloads as they varied widely in their magnitudes and in
the times and extents of their occurrences.
Even so, it was definitely determined that there were not present in the
municipal wastewaters, at least in effective concentrations, any materials
that were toxic or inhibitory to the treatment plant biota, Thus,
contrary to the opinions expressed by certain previous investigators, the
biological processes of the plant were not being affected by bacterio-
cidal or bacteriostatic substances in the wastewaters.
During the base-line studies of the investigation, it was discovered, too,
that among the biota of the treatment plant there was an appreciable
population of a filamentous sulfur organism, which, it is concluded,
markedly affected the settleability of the mixed liquor suspended solids
and contributed appreciably to the high-solids carry-over into the final
plant effluent that the plant had been experiencing for some time. This
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bacterial population, however, was subsequently eliminated from the
plant, in the pretreatment studies, through the preaeration of the raw
wastewaters.
Other conclusions that were drawn from the results of the investigation,
in particular the pretreatment studies themselves, are as follows:
1. Pretreatment of the municipal wastewaters by plain aeration,
by aeration with the addition of activated sludge, and by
chlorination were effective in improving the degree of waste-
water treatment achieved by the treatment plant.
2. Preaeration of the municipal wastewaters effectively reduced
the evolution of hydrogen sulfide gas from the treatment plant
and produced a better settling biological floe in the secondary
system by essentially eliminating from the aeration tank bio-
masses the above mentioned population of the filamentous sulfur
bacterium.
3. Pretreatment of the municipal wastewaters by addition of sodium
nitrate lead to the floatation (assumably through denitrification)
of raw primary and waste activated sludges deposited in the
primary settling tanks of the treatment plant and, in addition,
may have stimulated the growth of a hitherto unidentified
filamentous organism that appeared in such great abundance
during the application of this method that the settleability
of the solids in the aeration tanks and in the anaerobic
digesters of the plant were considerably impaired.
4. Pretreatment by addition of ammonia may have improved plant
performance somewhat; but, the experimental data are incon-
clusive as a consequence of the fact that the plant, during
much of the time period devoted to the study of this method,
was upset by severe hydraulic overloading.
5. No noticeable benefits were obtained by pretreatment with
potassium permanganate; however, it is felt that the dosages
applied were minimal and that higher dosages should have been
tried.
6. Pretreatment by chlorination increased color removal but only
at the higher chlorine dosages used in the pretreatment study.
The other pretreatment methods were not noticeably effective.
In addition, it is also concluded that, by the combination of substantial
reduction of stormwater inflow into the city's sewerage system, applica-
tion of pretreatment by plain aeration with the addition of waste activated
sludge and flow equalization over 24 hours of the slug discharges of the
cheese whey from the food processing plant, the Hagerstown Water Pollution
Control Plant should be able to achieve BOD5 removals of 90% or better.
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SECTION III
RECOMMENDATIONS
Based on the experimental data and conclusions of this project, the
following recommendations are offered:
1. The inflow of stormwater into the city's sanitary sewerage
system should be substantially reduced.
2. The batch discharge into the sanitary sewerage system of
significant amounts of high pollutional strength wastes,
noxious materials, and/or bacteriocidal or bacteriostatic
substances should be prohibited; and, the installation of
aerated waste flow equalization tanks by industries currently
practicing batch discharging of appreciable volumes of waste-
waters should be strongly encouraged.
3. Pretreatment of the municipal wastewaters by plain Deration,
or by the combination of aeration and the addition of waste
activated sludge, or by chlorination should be practiced.
4. Pretreatment of the municipal wastewaters by addition of
sodium nitrate should definitely not be employed because
of its adverse effects on the municipal treatment plant.
5. The use of other oxidants, such as ozone, pure oxygen and
hydrogen peroxide, for pretreatment should be explored; and,
the method of pretreatment with potassium permanganate should
be tried with higher permanganate dosages.
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SECTION IV
THE PROJECT SITE—THE HAGERSTOWN WATER POLLUTION CONTROL PLANT--
AND THE PROJECT FACILITY
A. Description of the Hagerstown Water Pollution Control Plant
The Hagerstown Water Pollution Control Plant is located on a 300-acre
farm in the southeastern part of the City of Hagerstown and receives the
wastewaters not only from the city but areas surrounding the city.
It serves a population estimated to be about 43500 people. The plant is
of the conventional activated sludge type with a design average hydraulic
load capacity of 7.5 mgd. However, in an effort to effect better treat-
ment, it now employs the contact stabilization modification of the
conventional activated sludge process. Its treated effluent discharges
into Antietam Creek, a major tributary of the Potomac River.
The original municipal treatment plant was constructed in 1924. Over the
years, as the city grew, the plant was improved and expanded. Today, the
plant (exclusive of the project facility) and the city's sewerage system
consist of the following units:
1. Outfall Sewer
A 54-inch reinforced concrete box sewer serving a separate sanitary
sewerage system laid throughout the confines of the city limits and
contiguous areas in Washington County. The capacity of the 54-inch
outfall is approximately 25.0 mgd.
2. Grit Removal Facilities
The existing grit removal facilities of the plant consist of two
grit chambers; one is a gravity type and the other, an aerated
type.
The gravity type grit chamber is 18'-0" x 18'-0" x T-6" normal
water depth with 2'-0" maximum water depth and is equipped with
a circular grit collector and other mechanical means for removing
grit from the unit. The volume at T-6" depth is 488 ft3 (3640 gal)
to give a detention time of 0.88 minutes at 6.0 mgd; the volume at
2'-0" depth is 648 ft3 (4850 gal) to give a detention time of 0.58
minutes at 12.0 mgd flow. Because this grit chamber does not give
satisfactory operating results, it is presently not used except as
a stand-by unit.
The aerated grit chamber, which has mechanical conveyor equipment to
remove the grit from the tank for disposal into a truck, is 18'-0"
long x 16'-0" wide x 12'-8" water depth at a flow rate of 12.0 mgd.
The detention time that this chamber provides at 12.0 mgd flow is
3.25 minutes.
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3. Screen and Comminutor
A manually cleaned coarse bar screen with 3-inch clear openings is
installed in the 54-inch outfall sewer ahead of the grit chambers
to catch and remove the heavy trash.
On the downstream side of the grit chamber, there is a Chicago Pump
Model 25A comminutor to cut up all coarse material in the sewage.
This machine has a capacity to handle wastewater flows from 1.5 to
25.0 mgd.
4. Primary Settling Tanks
The plant has two rectangular primary settling tanks, each being
75'-0" x 16'-0" with a 10'-0" water depth, which have a combined
volume of 179500 gallons and one circular primary settling tank,
which is 55'-0" in diameter with a lO'-O" side water depth and a
2'-3-1/2" deep hopper bottom and has a volume of 178000 gallons.
The plant, therefore, has a total primary settling volume of
357500 gallons. Each rectangular tank has a surface area of 1200
ft^ and the circular tank a surface area of 2380 ft^ for a total
settling area of 4780 ft*. Furthermore, each rectangular tank
has a weir length of 16 ft and the circular tank has a weir length
of 173 ft to give a total weir length of 205 ft.
5. Aeration Tanks
There are in the plant six spiral-flow aeration tanks in two
batteries of three tanks each. Each tank is 122'-Q" x 16'-0" x
15'-0" water depth, providing a volume of 29280 ft3/tank, 87800
ft3/battery or a total of 175680 ft3 for the six tanks. In addition,
the plant has a battery of two spiral-flow aeration tanks, each being
95'-0" x 30'-0" x 15'-0" water depth with a 42750 ft3 volume. The
total volume provided by eight aeration tanks is therefore 261180 ft3.
Of the six tanks constructed in two batteries of three tanks, each
tank has a double row of air diffuser tubes along one side and four
transverse wood baffles that divide the tank into five equal volume
sections and extend from above water surface to within one foot of
tank bottom to reduce short circuiting. Each aeration tank of the
two tank battery has air diffusion tubes mounted 2'-0" above the
tank bottom in two rows on 4-inch air headers suspended from six
"swing-diffuser" assemblies.
Although originally designed for the conventional activated sludge
process, the two batteries of three aeration tanks per battery and
the battery of two aeration tanks are operated in the contact
stabilization mode. The aeration tanks of each three-tank battery
are employed in series with return activated sludge being discharged
into the head end of the first of the three tanks in the series and
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primary effluent being introduced into the head end of the third or
last tank in the series. Thus, in each, three tank battery, the first
two tanks function as sludge reaeration tanks while the third tank
functions as a contact aeration basin. In the one battery of the
two aeration tanks, one of the two tanks serves as the sludge
aeration tank, and the other, as the contact aeration tank.
The return sludge to both of the three tank batteries is a combina-
tion of the settled activated sludges from the three settling tanks
that follow the two batteries. The return sludge to the two tank
battery is taken from the one settling tank that follows this
battery.
6. Final Settling Tanks
The flow from the battery of six aeration tanks is conveyed to two
square settling tanks and one circular settling tank which was
built during the construction of the project facility and brought
into use just before the beginning of the first pair of pretreatment
sludges. Each square settling tank is 50'-0" x 50'-0" x lO'-O" side
water depth with 3'-0" hopper depth and is equipped with a circular
type collector system. Each tank has a center feed well and two
weir troughs extending across the tank and one weir plate along a
side. And, each tank has a surface area of 2500 ft2, a volume of
195000 gallons and a weir length of 247 ft. The single circular
settling tank is 55'-0" in diameter x 10'-0" side water depth and
is equipped with a suction type sludge collector. The tank has a
surface area of 2380 ft2, a volume of 178,000 gallons, and a weir
length of 173 ft.
The flow from the battery of two aeration tanks is conveyed to one
circular final clarifier tank which is 60'-0" in diameter with a
11'-0" side water depth and a 2'-4-3/8" deep hopper bottom. The
tank is equipped with a circular sludge collector, which moves
sludge to sump located in center of tank. The tank has a volume
of 31100 ft3, a surface area of 2827 ft2 and a weir overflow length
of 188 ft.
Together, all the final settling tanks of-the treatment plant have a
total surface area of 10200 ft2, a total volume of 822,000 gallons
and a total weir length of 855 ft.
7. Chlorine Contact Tanks
There are two chlorine contact tanks, each being 61'-0" x 44'-0"
x 5'-0" water depth and having five dividing walls or baffles to
form end around flows in the 44-foot direction. Each tank has a
volume of 100650 gallons to give a total volume for chlorination
of 201300 gallons. These tanks are rather recent additions to the
treatment plant system. They were, in fact, constructed during the
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baseline study period of the research project and were not brought
into service until well after the pretreatment studies of the project
were initiated.
8. Sludge Thickening
Sludge from the primary tanks, which is a mixture of waste activated
and raw sludges, is thickened before going to the digesters in a
tank which is 20'-0" in diameter x lO'-O" deep and equipped with a
Dorr picket-fence type mechanical thickener. The volume of the tank
is 3140 ft3.
9. Sludge Digestion Tanks
Sludge from the thickening tank is pumped to one of five digesters.
Four of the digesters are heated by hot water circulated through
coils installed in the digesters and are mixed by gas recirculation.
The remaining digester is not heated or covered. It is used as a
sludge storage tank and is provided with a small aeration system
for mixing and scum breaking.
The capacities of these tanks are as follows:
Digester No. 1 (Primary) - 53015 ft3
Digester No. 2 (Secondary) - 49088 ft3
Digester No. 3 (Storage) - 53015 ft3
Digester No. 4 (Primary) - 53015 ft3
Digester No. 5 (Secondary) - 49088 ft3
The total capacity of all the digesters, excluding Digester No. 3,
is ft3; the total capacity of all the digesters, including Digester
No. 3, is 257221 ft3.
Digesters No. 1 and No. 4 are 50'-0" diameter x 24'-6" side water
depth x 5'-9" hopper depth and are provided with fixed steel covers.
Digesters No. 3 and No. 5 are 50'-0" diameter x 22'-6" side water
depth x 5'-9" hopper depth and are provided with gas storage type
floating steel covers. Digester No. 3 is of same size as Digesters
No. 1 and No. 4. As mentioned, it is open and serves as a sludge
storage tank as well as a digester. Sludges are normally pumped to
Digester No. 1 with overflow to Digester No. 2 and from there to
Digester No. 3, or into Digester No. 4 with overflow into Digester
No. 5 and from there to Digester No. 3.
10. Sludge Drying Beds
Although most of the digested sludges are carted away by tank trucks
for disposal on farm lands, the treatment plant has four open sludge
drying beds, each 90 ft x 26 ft, and six beds, each 121 ft x 47 ft,
enclosed by a structure having a steel roof and open sides. The
total drying bed area is 43482 ft?.
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11. Return Sludge Pumps
The sludges from the two 50-foot square and the one 55-foot
diameter circular clarifiers are pumped by either one or both
of two 1900 centrifugal pumps to the battery of six aeration
tanks, through two 8" discharge lines.
The sludge from the 60-foot diameter circular clarifier is
pumped by either one or both of two 950 cfm centrifugal pumps
to one aeration tank of the battery of two aeration tanks.
All pumps are provided with constant speed motors and the rates
at which sludges are returned are controlled by throttling gate
valves in the discharge lines of the pumps. Total return sludge
capacity of the plant is 5700 gpm or 6.1 mgd with all pumps
operating.
12. Blowers
Air requirements are furnished by the following equipment:
(1) One Roots-Connersville two speed positive displacement
type blower with maximum capacity of 2562 cfm (1900 cfm
at 695 rpm, 2562 cfm at 870 rpm);
(2) Two Ingersoll-Rand Centrifugal blowers, each rated at
1500 cfm to 3000 cfm; and,
(3) One Chicago Standardaire two speed positive displacement
blower with maximum capacity of 1600 cfm (900 cfm at
1150 rpm, 1600 cfm at 1750 rpm).
The air lines are interconnected so that air from all blowers can
supply all aeration tanks.
B. Capacities of Existing Sewage Treatment Units
1. Grit Chambers
Each grit chamber is designed for a capacity of 12.0 mgd; thus,
both units together have a maximum capacity of 24.0 mgd.
2. Comminutor
The comminutor is rated for a maximum capacity of 25.0 mgd.
15
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3. Primary Settling Tanks
At 10.0 mgd flow, these tanks provide a detention time of 51.5
minutes, a surface settling rate of 2100 gals/ft2/day and a weir
overflow rate of 48800 gals/ft/day.
4. Aeration Tanks
With a total volume of 1950000 gallons and based on mixed liquor
suspended solids concentration in the aeration tanks of 3500 mg/1
and loading of 35 Ibs 6005 per 100 Ibs solids, the organic load
capacity of aeration tanks is:
Ibs BOD5
- - - - = 1.95 mgd x 3500 mg/1 x 8.34 = 19850 Ibs/day
Uajr
Assuming Average BOD5 of 225/mg/l , the waste flow yielding
the above loading would be
Flow = = 10.6 mgd
8.34 x 225
»
The detention time in the aeration tanks at 10.0 mgd flow would
be 4.68 hours. (The detention time at design flow, 7.5 mgd, is
6.2 hours.)
5. Final Settling Tanks
Based on surface settling rate of 1000 gals/ft^/day, the settling
tanks can handle 10.2 mgd per day, providing a detention time of
1.93 hours and a weir overflow rate of 11930 gals/ft/day.
6. Chlorine Contact Tanks
The volume of 201300 gallons at 30-minute detention time provides
sufficient capacity to handle an average flow of 9.67 mgd.
7. Sludge Digestion
Since high rate digestion by gas recirculation is rated at 2.0
ft3 per capita, the four anaerobic digesters with a total volume
of 204206 ft3 can handle a total equivalent population of 102103
persons. Therefore, even without the digester/storage tank, the
digester capacity of the treatment plant is more than adequate.
8. Sludge Drying Beds
Sludge drying beds rated at 1.5 ft3 per capita and having an area
of 43482 ft2 can handle an equivalent population of 29000 persons
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and with tank truck disposal as the major method of disposing the
sludge, sludge bed capacity is adequate to serve during weather
periods when tank truck disposal is not possible.
C. Project Modifications of the Hagerstown Hater Pollution Control
PTant "~
In order to be able to carry out two pretreatment studies at the same
time in accordance with the project program plan, it was necessary to
have the effluents from the two aeration tanks of the pretreatment
facility fed separately to two independent treatment systems--each
system having its own primary and secondary units and distinct sludge
return systems. Because of the layout of the Hagerstown plant, the
dividing of the plant into two separate treatment systems required only
minor changes in the piping arrangement of the plant.
Specifically, the following changes were made in the treatment plant
piping system:
The concrete wastewater distribution box that precedes the primary
settling tanks of the treatment plant was hydraulically connected to the
longitudinally divided effluent channel of the pretreatment facility and
sectioned by means of a simple, transite divider wall into two compart-
ments. The sectioning was done in a manner such that in the box the
effluent from one pretreatment tank (referred as pretreatment Tank A)
would flow to and be distributed between the two rectangular primary
settling tanks and the effluent from the other pretreatment tank
(pretreatment Tank B) would flow into the circular primary settling tank
of the treatment plant.
The piping for the circular primary tank effluent was changed to enable
this effluent to be conveyed directly to the contact aeration tank of the
two-aeration-tank battery; and the piping for the rectangular primary tank
effluents was modified so that these effluents would flow to only the
contact aeration tanks of the two three-aeration-tank batteries. Originally,
the effluent of the circular primary tank was combined with the effluents
from the rectangular settling tanks; and, then, the combined primary
effluent flow was distributed among the three contact stabilization tanks
of the treatment plant.
No further piping changes were necessary in the existing plant since the
wastewater flow entering the two three-tank batteries and the flow enter-
ing the one two-tank battery are not combined until the treated wastewaters
are finally discharged to the receiving stream and since the return sludge
systems of the two groups of aeration tanks were already separate systems.
As a result of these few piping changes, the plant was able to function
as two distinct and independent treatment systems. The two distinct
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treatment systems thus formed are referred to herein as Systems A and B
and were comprised of these treatment plant units:
Treatment System A Treatment System B
1. Pretreatment Tank A. 1. Pretreatment Tank B.
2. The two rectangular primary 2. The circular primary settling
settling tanks. tank.
3. The two three-aeration-tank 3. The battery of two aeration
batteries. tanks.
4. The two square and the 55-foot 4. The 60-foot diameter circular
diameter circular final final settling tank.
settling tank.
D. Project Facility
1. Design of the Project Facility
Immediately after the initiation of the research project, certain
preliminary engineering studies of the project site were made to
secure those site data needed to design and to integrate struc-
turally and hydraulically the project facility into the existing
Hagerstown treatment plant. A survey crew gathered data on
pertinent ground elevations and invert elevations of existing pipe
lines, channels, and junction and distribution boxes. These data
then were used to prepare a preliminary site plan showing the
critical invert elevations and site topography. On the basis of
the survey data and prepared site plan, engineering determinations
were made as to the best location for the two pretreatment tanks
and the facility influent and effluent conduits; and, subsequently,
preliminary plans of the project facility were developed.
The plans that were generated called for the aeration tanks of the
facility to be located between the existing comminutor chamber and
the concrete division box that distributes the wastewater to the
primary settling tanks of the plant. It was known, however, that
the hydraulic head differential between the chamber and the box was
rather small; but, it was not known for certain how small. Conse-
quently, to ensure that accurage design data were available, field
measurements of water levels were made at key points in the treatment
plant system during low and high sewage flows and during wet weather
conditions. These field measurements extended from a low flow of
2.3 MGD to a high flow of 30.4 MGD. The resulting data confirmed
the tightness of hydraulic conditions for the proposed facility,
they showed that it was feasible to locate the facility as proposed
in the preliminary plan. Subsequently, the final engineering plans
for the facility were generated and approved.
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EFFLUENT
AERATION TANKS (B)
FINAL TANK
CHLORINE CONTACT TANK
Figure 1. Schematic Diagram of the Hagerstown Water Pollution Control Plant
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The fundamental considerations that were made in the planning of the
project facility were that: (1) the facility must fully meet the
needs of the project program for such a structure, (2) the facility
ought to be useable for post project pretreatment operations involv-
ing the entire plant including any likely plant expansions, (3) the
wastewater flow into and out of the facility should be by gravity
to obviate the need for pumping, (4) the loss of head through the
facility must be minimal, (5) the Hagerstown treatment plant must
be able to continue to operate while the facility is being constructed,
and (6) the cost of the facility should be as low as reasonably
possible.
2. Description of the Project Facility
The project pretreatment facility, which consists of two aeration
tanks (i.e., pretreatment tanks) of compressed-diffused air design
with their influent and effluent channels and a building for housing
the facility equipment—blowers, electrical controls, wastewater
monitoring and sampling units, chemical feed machines, etc.—was
constructed as planned ahead of the primary settling tanks and
downstream from the comminutor basin of the Hagerstown Water
Pollution Control Plant.
A concrete manhole located 80 feet downstream from the comminutor
basin was enlarged under the facility construction task of the project
to receive a 42-inch concrete pipeline that also was built under the
project to intercept the raw wastewater flow of the plant at the
manhole and carry it some 100 feet to the aeration tanks of the
pretreatment facility. Two stop gates were installed in the enlarged
manhole in order that the raw sewage could be allowed to flow through
either the 42-inch concrete influent line of the pretreatment facility
or the original 42-inch line of the treatment plant in order to by-
pass the facility. The 42-inch influent line of the facility discharges
into the head end of a grating-covered V-shaped channel formed in and
running the full length of the coping wall that separates the two
facility pretreatment tanks. An air diffusion system is installed
in the coping wall channel itself to prevent deposition of wastewater
solids in the channel. Toward the end of the coping wall channel,
the channel is divided so as to split the .wastewater flow into two
separate streams. At the very end of the channel, these two flow
streams are then directed downward through separate openings in the
bottom of the divided channel and into vertical down channels that
are formed in the corners of the pretreatment tanks. These vertical
down channels extend below the line of air diffuser elements in the
pretreatment tanks so that each of the two separate wastewater flow
streams is introduced into its respective pretreatment tank at a
point where rapid and vigorous mixing can occur.
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Each pretreatment tank is 30'-0" wide x 95'-0" long with a 15'-0"
maximum water depth for a total water capacity for both tanks of
6.30 x 105 gallons (8.40 x 10^ ft3). At the average design flow
for the treatment plant (7.5 MGD) the water depth in the tanks is
14'-3" and total capacity of the tanks is 6.00 x 105 gallons
(8.00 x 104 ft-3) for a detention time of 2.0 hours. The tanks as
aeration basins are of the spiral flow design with swing type air
diffusers (Chicago Pump "Swing Diffusers"). There are seven swing
diffuser assemblies in each tank with 12'-10" air headers each
equipped with 16 Chicago Pump "Shearfuser" air diffuser elements
mounted on 9-inch centers and 7 evenly spaced Chicago Pump "Discfuser"
diffusers mounted on piping that extend out from the headers to
beneath the coping wall. The purpose of these discfusers is to
prevent the formation during aeration of a dead volume (confined
roll) under the appreciable overhang of the coping wall.
In the end wall of each pretreatment tank—the end wall at the head
of the coping wall channel and opposite the end wall where the waste-
water flow is introduced into the tank—a 48-inch wide rectangular
opening is provided to connect the tank to a 48-inch wide rectangular
channel that carries the tank effluent to the previously mentioned
concrete division box of the treatment plant that distributes the
wastewaters to the primary settling tanks. During all of the pre-
treatment studies except the last, pretreatment by the "select
method" involving the operation of the entire treatment plant as
a single system, this 48-inch wide effluent channel was divided by
an asbestos-board divider wall into two channels to provide a
separate channel for each pretreatment tank effluent. This division
was carried up to and, as mentioned, through the concrete division
box. In addition, because it was anticipated that low-flow velocities
would exist in the 48-inch wide effluent channel, an air pipe line was
installed in the channel in order that the effluent waters in either
the channel as a whole or its divisions could be aerated to keep
particulate solids in suspension.
In order to be able to bring waste activated sludge to the head
ends of the pretreatment tanks and there to mix the sludge with the
incoming raw wastewater as required by the project program plan, the
6-inch waste activated sludge line of the treatment plant that
terminated in the concrete division box preceding the primary tanks
was extended to the influent end of the pretreatment tanks where
another concrete box was built to receive the extended line and to
distribute the sludge to either or both of the coping wall influent
channels of the pretreatment tanks. This sludge distribution to
either or both influent channels was made controllable by means of
adjustable discharge weirs in the concrete sludge distribution box,
each weir leading to one channel in the coping wall. Pumping of
waste activated sludge to the pretreatment tanks can be accomplished
as required by one or both of two activated sludge pumps of the
treatment plant. These pumps, which as stated earlier, have a
capacity of 1900 gpm each when pumping sludge to the concrete
21
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distribution box ahead of the primary tanks, lose about 35% of their
pumping capacity when pumping sludge to the sludge distribution box
of the pretreatment tanks. This loss stems from the increase in the
total dynamic head of the pumping system as a result of the extension
of the sludge line. During the project, a single pump provided, as
anticipated, all the pumping capacity necessary however to satisfy
the sludge pumping requirements of the project program.
Housed in the mechanical building of the project facility are the
following facility equipment, which were purchased and installed
under the grant program:
(1) Two Ingersoll-Rand positive displacement blowers each capable
of delivering to the pretreatment tanks 3500 cfm of air at
15 psig.
(2) Two mercury manometers reading 0 to 10 psig and. mounted in
the discharge piping of each blower to measure to the air
pressure in the lines.
(3) Two Permutit Company Permatubes fitted with manometers and
installed in the two air mains of the facility leading from
the blowers to the pretreatment tanks. These are Venturi
type devices for measuring the air flows to the pretreatment
tanks.
(4) Three Chicago Pump Tru-Test Samplers for collecting and holding
under refrigeration composite samples of the common influent
(raw wastewaters) and the separate effluents of the two pre-
treatment tanks. These samplers are capable of sampling either
proportionally to the raw wastewater flow (being paced by the
plant flow meter located at the head end of the treatment system)
or at a constant rate which is set by a timer-controller provided
with each sampler. They are dip type samplers and each can take
three to twenty 25-ml sample aliquots per hour and automatically
composite them into a single sample and store the composite in a
2-gallon bottle kept in a refrigerated compartment in the unit.
(5) Three Megator L 100 positive displacement "Snore Pumps" for
pumping the various wastewaters to the Tru-Test Samplers. These
pumps are located next to the samplers in the mechanical building
of the pretreatment facility and are driven by one horsepower,
1150 rpm electric motors through variable pitch pulley and belt
drives to give a range of pumping rates.
(6) An electronic wastewater quality monitoring system for continuous
automatic measurement and recording of the pH's, dissolved oxygen
concentrations and oxidation-reduction potentials of the pre-
treatment tank influent and effluents. This system was manufactured
by Automated Environmental System, Inc. During the project the
22
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sensing probe assemblies of the system were mounted in the
submersible, stainless-steel baskets that were placed just
outside of the mechanical building of the project facility
in the appropriate wastewater channels.
(7) An ammoniator-chlorinator for metering and feeding tank
ammonia or chlorine in solution form into the pretreatment
tanks. This device is a Wallace and Tiernan Modular Series
V-800 Chlorinator with a capacity for feeding 2000 Ibs of
chlorine per day and, through slight modification, 950 Ibs
of ammonia per day. By means of the chemical feed-line-
piping-and-valving arrangement of the project facility, the
ammoniator-chlorinator can supply either ammonia or chlorine
to either or both of the pretreatment tanks. The feed machine,
for obvious safety reasons, is installed in a separate, well
ventilated room in the mechanical building. On the open con-
crete pad of the building are located the manifolds and storage
areas for the ammonia 150-lb and chlorine 2000-lb cylinders for
the gas feed machine.
(8) Two chlorine scales, Force Flow Equipment Chlor-Scale Model
6D80, which are installed in the concrete pad of the mechanical
building and are sized to hold and weigh two 1-ton chlorine
cylinders each. The scales read from 0 to 8000 Ibs.
(9) A dry chemical feeder for metering and feeding sodium nitrate
and potassium permanganate to the pretreatment tanks. This is
a Wallace and Tiernan, Inc., Screw-Type Volumetric Feeder,
Series A-690, having a control feed range of 20 to 1 and a
maximum feed rate for pelletized sodium nitrate of 1170 Ibs/day
and for "free-flowing" potassium permanganate of 312 Ibs/day.
The feeder meters and deposits powdered chemicals into a
35-gallon solution tank contained in its base where the dry
chemicals with the aid of a mechanical stirrer are dissolved
in tap water. From the solution tank, the dissolved chemicals
can be fed by gravity flow to either or both of the pretreatment
tanks. The machine is equipped with a 28-ft3 hopper extension
to provide a total hopper capacity of 6.0 ft3. The additional
hopper capacity provided by the extension allowed enough sodium
nitrate to be stored in the machine that when the machine was
used to feed sodium nitrate at the maximum rate, it refilled
not quite once each shift. (Bulk density of sodium nitrate is
approximately 75 lbs/ft3)
23
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•• -
Figure 2. A View of the Pretreatment Facility from the Head End of the Pretreatment Tanks
-------
r j
Figure 3.
A View across the Pretreatment Tanks of the Project Facility, Showing the
Primary Settling Tanks and Other Parts of the Hagerstown Water Pollution
Control Plant in the Background
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Figure 4. The Project Facility immediately prior to
Wastewaters into the Pretreatment Tanks
the Introduction of the Municipal
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SECTION V
BASELINE STUDIES
A Preliminary Wastewater Analyses
.1. Establishment of Analytical Procedures
Shortly after the project was begun, an inventory of the equipment
and chemicals in the laboratory of the Hagerstown sewage treatment
plant, was conducted and those laboratory items that the laboratory
did not have but that would be needed for the project were purchased.
As had been proposed, the purchases were made partly with project
funds designated for this purpose and partly with "non-project
funds" provided by the city. Once analytical systems were set up,
laboratory personnel were trained by the professional chemists of
the project team in carrying out those standard analytical tests
that the laboratory personnel were not familiar with and that would
be conducted routinely throughout the lifetime of the project.
All standard chemical analyses performed on wastewaters during the
project except for the determination of the oxygen demand indicates
(GDI's) and sulfite and hydrogen sulfide contents of wastewaters
were conducted in accordance with the 12th Edition of Standard
Methods for the Examination of Water and Wastewater, 1960, APHA,
AWWA and WPCF.The ODI determinations were done following the
Hach procedure patterned after the Department of Public Health of
Illinois ODI test. The sulfite concentration measurements were done
using the Hach SU-2 Sulfite Test Kit and the hydrogen sulfide con-
centration determinations were made by means of the Hach "Screening
Test for Soluble Sulfides." These Hach procedures were adopted be-
cause of the rapidity and ease with which they could be performed
by most of the personnel of the plant.
While laboratory personnel were being trained and for a short time
thereafter, all the adopted standard analytical procedures were checked
carefully and all the analytical instrumentation was meticulously
checked to insure that all analytical measurements would yield
reasonably accurate results for all the various analytical conditions
that would be encountered in the different operational studies of the
project. Moreover, several techniques for using gas chromatography
to detect and to trace through the treatment plant various volatile
organic components of the Hagerstown wastewaters were explored.
Among the several candidate chromatographic techniques examined,
the techniques or, more precisely, combination of techniques that
were judged to be most suitable for the project and, therefore,
adopted for project use were "freeze concentration" of the volatile
27
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wastewater organics for improved detection, injection and volatili-
zation of the concentrated samples in the gas chromatograph,
separation of the volatile organics on either a SE-30 or Porapak Q
thermally programmed column, and detection of the separated components
by means of a flame ionization detector. The gas chromatograph used
was a Beckman CG-5.
2. Analysis of Wastewaters
While the project facility was being constructed, the mixed liquor
suspended solids (MLSS) levels in the contact aeration tanks of the
treatment plant were brought up to and maintained at 2500 ± 500 mg/1
in order to have reasonable concentrations of biologically active
solids in these tanks. Many analyses were then conducted on the
wastewater flowing into, through and out of the plant in order to
ascertain the nature of the raw wastewaters and the operational
effectiveness of the various treatment plant sections as well as
of the whole plant itself. These analyses, determined the baseline
conditions of the project and are discussed in some detail below.
a. Sanitary Chemical Analyses
On each day of a seven-day period in July 1969, grab samples
of the raw sewage and primary effluent were collected at 0100,
0200, 0300, 0400, 0500, 0600, 0800, 0900, 1100, 1500, 1700,
1900, 2100, 2300, and 2400 hours and grab samples of the final
effluent of treatment plant section 3 (subsequently known as
System B) were collected at 0300, 0600, 0900, 1200, 1600, 2000,
and 2400 hours. Immediately after each sample was collected, its
conductivity, dissolved oxygen concentration, and pH were measured.
The samples were then acid preserved and, as soon as it was practi-
cal, their COD's and GDI's (oxygen demand indices) were determined
with their colors being noted; in addition, the BODs's of those
samples of (1) the raw sewage that were collected between 0100
and 0700 hours, (2) the primary effluent that were collected
between 0200 and 0800 hours, and (3) the final effluent that
were collected at 0300, 0600, 0900, and 2400 hours were measured.
The BOD, COD, and ODI measurements gave exceptionally high values
for the raw wastewater samples collected during the early morning
hours of the week days. The COD and BOD values of the raw waste-
water samples obtained during these times generally exceeded 1000
and 400 mg/1, respectively, with recorded highs: of 1750 and 840
mg/1, respectively. During other times over the sampling period,
BOD's values were less with the lowest values usually falling in
the 30 to 40 mg/1 range, while COD's values were also lower and
dropped down into the 200 to 400 mg/1 range. Thus, the raw
wastewaters entering the treatment plant on week days were found
to vary greatly in their pollutional strength, not only from day
to day but from hour to hour. On the other hand, the BOD and COD
28
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values of the grab samples collected on the weekend that fell
within the 7-day sampling period did not vary as markedly. Most
of these BOD values were in the range of 30 to 120 mg/1; and most
of the COD values, in the range of 130 to 400 mg/1. The BOD, COD,
and ODI results obtained on the primary effluent grab samples were
also higher for those samples collected during the week day
morning hours than for those samples collected at other times;
however, their peak values were never as high as the peak values
obtained for the raw sewage samples and they lagged the raw
sewage peak values in time by about two to three hours yet per-
sisted for longer periods to show (as would be expected) that
the slug loads that hit the plant during the morning hours were
smoothed out somewhat as they passed through the primary tanks.
A plot against collection times of ODI values obtained on samples
of primary effluent that were grabbed hourly over seven consecutive
days is shown in Figure 3. This plot dramatically illustrates the
slugging of the aeration basins of the plant on week day mornings
with a waste flow containing appreciable quantities of oxidizable
materials. The BOD and COD results obtained on final effluent
grab samples were in the ranges of less than 10 to 150 mg/1 and
120 to 600 mg/1, respectively.
The chlorine demands of the raw sewage samples grabbed nearly once
each hour over two separate 24-hour periods were determined for 30-,
45-, and 60- minute contact times. During the first of the 24-hour
sample collection periods, the raw waste flow exhibited the early
morning peak in ODI values, while during the second of the 24-hour
periods the waste flow did not; however, the chlorine demands for
both periods, even over the early morning hours, did not offer
appreciably, running between 5 and 15 mg/1 for 30 minute contact
times. Chlorine demands at 45- and 60- minute contact times ran
only slightly higher than those at 30-minute contact times.
Over another seven-day period, grab samples of the raw sewage,
primary effluent, and Section No. 3 final effluent were collected
hourly and composited daily, with sample preservation being
effected during daily compositing period by refrigeration. The
daily composites were then analyzed for their total phosphorous
concentrations (soluble and soluble plus insoluble), oil and
grease concentrations (by the Freon extraction procedure), COD's
and BODs's (soluble and soluble plus insoluble), dissolved solids
concentrations, suspended solids concentrations, specific con-
ductances, chloride ion concentrations, pH's, and oxygen uptake
rates. A similar set of daily composites spanning a third seven-
day period were collected and analyzed for their ammonia nitrogen
concentrations, organic nitrogen concentrations, nitrite nitrogen
concentrations, COD's, sulfide concentrations, sulfate concentra-
tions, total sulfur concentrations (sulfide, sulfite, hydrolyzable
sulfonate, and sulfate sulfur as sulfate), specific conductances,
29
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co
o
22 i—
20
18
16
14
5 10
o
J L
J L
J L
J L
J L
6 12 18
WEDNESDAY
6 12 18
THURSDAY
6 12
FRIDAY
6 12 18
SATURDAY
Time (hours)
6 12 18
SUNDAY
6 12 18
MONDAY
12 18
TUESDAY
Figure 5. Oxygen Demand Indices (GDI's) of Grab Samples of Primary Effluent Collected
over the period of October 18 to October 24, 1967
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and pH's. The significant findings obtained from these analyses
are summarized below:
(1) The BOD values of the composite samples of the raw sewage
ranged between 200 and 300 mg/1 and the BOD values of the
composite samples of the final plant effluent (i.e., Section
3 effluent), from 45 to 150 mg/1 with daily BOD removals
averaging about 70%. The soluble BOD's of all the samples
regardless of type—i.e., raw sewage, primary effluent or
final effluent—were generally 70% of the total BOD's of
the samples, although this percentage often varied quite
widely among samples of even the same type.
(2) The concentrations of total phosphorus (expressed as ortho-
phosphate) in the unfiltered samples fell in the range of
20 to 40 mg/1. The phosphorus concentrations in the filtered
samples were not much less than the phosphorus concentrations
in the corresponding unfiltered samples, thereby revealing
that most of the phosphorus in the different wastewater
samples was in solution.
(3) The chloride concentrations in the samples ranged between
48 and 75 mg/1 and averaged 61 mg/1.
(4) Significant sulfide concentrations—0.1 to 3 mg/1—were
present in nearly all samples.
/
(5) The total sulfur concentrations in the samples ranged
between 80 to 120 mg/1 as sulfate.
(6) The concentrations of ammonia nitrogen in the raw wastewater
samples were about 20 mg/1 while the concentrations of
organic nitrogen were about only 5 mg/1. The relatively
high ratio of ammonia N to organic, it is believed, is
indicative of considerable decomposition of proteinaceous
materials occurring in the raw wastewaters before these
waters reach the treatment plant.
(7) Only rarely were there not detectable concentrations of
nitrate or nitrite in any of the samples. Generally, all
the samples including those of the raw sewage had nitrate
and nitrite; but, the concentrations of these anions in
terms of nitrate or nitrite nitrogen were never greater
than 0.2 mg/1; and, in many of the samples, these concen-
trations were only at trace levels. In addition, the
effluent samples consistently contained smaller concentra-
tions of nitrate and nitrite than did the corresponding
samples of raw sewage and primary effluent.
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(8) The specific conductances of plant Influent and primary
and secondary effluent samples composited over a single
24-hour period varied little from one another; and, over
the entire week of sampling, specific conductance values
of daily composited samples fell in the rather narrow range
of 180 to 390 pmhos/cm with 309 pmhosAim being the typical
value.
(9) Over the sampling period, the pH values of raw sewage
samples averaged 7.2; the primary effluent samples, 7.2;
and the final effluent samples, 7.4.
(10) The levels of suspended solids in both the raw sewage and
the final plant effluent varied greatly from day to day.
The suspended solids concentrations in 24-hour composite
samples of raw sewage ran as low as 58 and as high as 986
mg/1 and in 24-hour composite samples of the final effluent,
from 22 to 196 mg/1. The volatile portion of the influent
suspended solids also varied, ranging from 70 to 100%.
Typically, the plant influent contained about 250 mg of
suspended solids per liter while the plant effluent had
about 95 mg per liter. The regular occurrence of high
suspended solids concentrations in the final effluent was
a major operational problem of the treatment plant and,
except for the extremely frequent production of malodorous
hydrogen sulfide gas by the treatment plant, was the most
obvious deficiency in the performance of the plant.
In the baseline study, not only were sulfide concentrations
of significant proportions found in grab and composite
samples taken from various points throughout the treatment
plant; but, by means of lead acetate impregnated filter
papers suspended over the wastewaters at different points
in the plant, hydrogen sulfide gas was found to evolve
almost continuously from the wastewaters that were dis-
charging over the effluent weirs of the primary and final
settling tanks—as well as from the mixed liquors that were
being aerated in the sludge reaeration and contact aeration
tanks.
In extending the routine wastewater testing program of the
treatment plant, sulfite tests on grab samples of the raw
sewage were made regularly throughout the period of project
baseline study. These tests were closely followed because
of the high immediate oxygen demand that sulfites exert and
because of the quite large sulfite concentrations that were
reported to have been found entering the Hagerstown treat-
ment plant prior to the initiation of the research project.
The tests showed that during the baseline study sulfites
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were^often present in the raw wastewaters for short periods
of time, and that their concentrations generally ranged from
0 to 3 mg/1. Although sulfite levels as high as 7 and 10
mg/1 were found, no concentrations of sulfite were detected
that were as high (i.e., >25 mg/1) as many of those reported
prior to the development of the project plan.
In addition to the dissolved oxygen analyses performed on the
various wastewater samples, dissolved oxygen profiles of
various plant sections were run with dissolved oxygen measure-
ments being made in situ by means of a Weston-Stack dissolved
oxygen meter. These measurements were made throughout the
treatment plant every 8 hours over a 7-day period. Generally,
extremely low dissolved oxygen levels were found to exist
throughout the entire treatment system. Incoming wastewaters
and the wastewaters in the primary tanks were found to have
no dissolved oxygen, except rarely, then only in trace
amounts. The wastewaters entering the aeration tanks often
had slight amounts of dissolved oxygen as a result of having
been discharged over the weirs of the primary tanks. Dissolved
oxygen levels in the aeration tanks were usually in the order
of tenths of a mg/1 although they occasionally did reach
1 mg/1 or more. The wastewaters in the final settling tanks
usually contained no oxygen also but upon being discharged to
the receiving stream did pick up some oxygen. As a rule,
dissolved oxygen levels ran somewhat, though not appreciably,
higher on the weekend than on the week days of the 7-day
study period.
3. Oxygen Uptake Measurements
The rates at which the dissolved oxygen concentrations would be
depleted in well aerated 24-hour composite samples of raw sewage,
primary effluent, and final effluent was investigated. It was found
that dissolved oxygen levels in well aerated (oxygen saturated) raw
sewage and primary effluent samples that were collected on week days
would drop from 7 mg/1 to less than 0.5 mg/1 in 25 to 35 minutes while
in that same length of time the dissolved oxygen concentrations in well
aerated final effluent samples that were also collected on week days
would drop by only about 30%. It was also found that weekend samples
of raw sewage, primary effluent, and final effluent consumed oxygen
at appreciably lesser rates than their week day counterparts.
A number of mixed liquor samples were collected over the preliminary
analysis task period of the project and the rates at which they took
up oxygen were also measured, the measurements being made by means
of Warburg Apparatus (Aminco, 18-station Model). Samples taken from
the tail end of the sludge reaeration tank of Section No. 3 had
oxygen uptake rates of 5 to 9 mg 02/g MLSS/hour and samples taken
33
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from the head end of the contact aeration tank of the same section
had oxygen uptake rates of between 10 and 20 mg 0Ł/g MLSS/hour.
Besides these measurements, several 1:1 mixtures of sludge re-
aeration tank mixed liquor and composite raw sewage samples collected
on week days were examined and they showed healthly oxygen uptake
rates of around 20 mg Oo/g MLSS/hour. It is felt that these high
uptake rates displayed By the mixtures strongly indicate that the
wastewater used in the mixtures, which seemed typical of the raw
sewage entering the treatment plant on week days during the project,
contained no toxic and/or inhibitory substances.
!.._ rt'uiburg Apparatus was also used to check for the possible presence
in the wastewater of toxic or inhibitory materials in another way:
The 5-day BOD of a raw wastewater sample that was composited over a
24-hour week day period was determined by both the standard dilution
method and the direct method, which requires the Warburg Apparatus.
Both methods gave BODs values for the sample that were in good
agreement. Thus, dilution of the sample (which was 100:1 in the
dilution method) had no major effect on its BODs value. Consequently,
it is reasonable to assume that in all likelihood toxic and inhibitory
materials, if present in the raw sewage, were not present in sufficient
amounts to affect biological activity.
4. Microscopic Examinations of Plant Biota
As a part of the preliminary analyses that were performed, microscopic
examinations were made of the wastewaters from active parts of the
Hagerstown treatment plant. These examinations revealed that the
outstanding feature of the zoogleal floe mixes from the aeration tanks
of the treatment plant was the universal presence of filamentous
"sulfur bacteria" growing among relatively small and stringly zoogleal
bacterial masses (see Figure 3). These filamentous sulfur bacteria
were of the type commonly found in activated sludges receiving hydrogen
sulfide, mercaptans, and other reduced sulfur compounds. The filamentous
bacteria were readily distinguishable by their motility--they exhibited
bending and creeping movements, much like the blue-green algae,
Oscillatoria. They consisted of a series of nearly cylindrical cells,
aligned in a common capsular sheath. Refractile masses of elemental
sulfur appeared at intervals in the filaments. It is generally
believed that these sulfur deposits represent the end product of the
oxidation of hydrogen sulfide to sulfur and that the reaction is not
carried further by the bacterial group.
Besides being found in the mixed liquors, the filamentous sulfur
organisms were also observed in the raw sewage, and in the primary
tank and final tank effluents. It is general experience that solids
bearing filamentous bacteria settle poorly. Consequently, it was
felt that if these sulfur organisms could be eliminated from the
treatment system by destruction of hydrogen sulfide and other reduced
sulfur compounds serving as their source of energy, a more
34
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..
'* .
•-»»•
> ?$~* >•
Figure 6. Photomicrograph of the Aeration Tank Mixed Liquors, Taken during the
Baseline Study and Showing Filamentous Sulfur Bacteria Containing
Globules of Sulfur and Growing among Masses of Zoogleal Bacteria
-------
readily settleable floe would be generated and better manage-
ment of the treatment process would be possible. It was hoped, of
course, that the pretreatment schemes using oxidants would achieve this
this destruction of reduced sulfur compounds.
It is interesting to note in view of the considerable quantities of
hydrogen sulfide that were in the wastewaters that the microscopic
examinations that were made did not reveal the presence of micro-
organisms of the type that produce hydrogen sulfide. However, it is
believed that they were indeed in the plant, perhaps attached to the
sidewalls of the various tanks.
5. Color Measurements
As another part of the baseline study, many wastewater samples were
collected over a four-day period from three sections of the Hagerstown
water treatment plant. The four-day period ran from a Thursday
through a Sunday and the hourly and multi-hourly collections yielded
representative grab sample of raw waste, primary effluent and final
effluent, as well as 24-hour composites of these waters. The samples,
over 90 in all, were analyzed to determine the color characteristics
of wastewaters (which are usually intensely colored as a result of
the dye wastes they contain) and how these characteristics changed
as the wastewaters flowed through the plant.
The following observed trend and general conclusions were derived
from the experimental data:
a) Typical color data in final form appeared as follows:
Type Date Time % Luminance Hue % Purity
Raw 1/22 1100 84 greenish-yellow 5
Primary 1/22 1300 85 greenish-yellow 4
Final 1/22 1800 98 greenish-yellow <1
Raw 1/23 1500 89 greenish-yellow 8
Primary 1/23 1700 94 yellow 2
Final 1/23 2100 97 yellow-green 1
b) Part (a) typifies the general trend in the samples. The hues of
the samples seldomly changed significantly from raw to final and
over 90% of them fell into the blue-green to yellow range of the
spectrum. In the majority of cases, the degree of brightness was
36
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relatively high and increased from raw to final, while the
corresponding values for color saturation were very low and
decreased that same sequence.
c) Weekend grab samples were almost exclusively in the greenish-
yellow range. Their percent purity and percent luminance
indicated a somewhat better quality to the waste. This probably
is attributable to lesser volumes of dye wastes discharged into
the system at this time of the week.
d) The 24-hour composites displayed an overall lack of change from
sample to sample. Only three of the eleven composites were not
greenish-yellow, these three being green, blue-green, and yellow
respectively. Here again, the percent purity was very low in all
the samples.
6. Detection of Volatile Organics
As part of the investigation of treatment plant performance and wastewater
characteristics, gas chromatography was employed to trace certain organic
pollutants in the wastewaters through the various sections of the plant
and to "fingerprint" the-various industrial wastes entering the plant.
Wastewater samples used in this work fell into three groups:
(1) Hourly grab samples taken from manholes near industries
suspected of discharging high strength, extremely noxious,
or toxic wastes into the city's sanitary sewerage system.
The sampling points were chosen such that the wastes from
any one particular industry would be isolated from those
from any other industry. Some of these samples were
collected from 0000 (midnight) to 0800 hours as part of
an effort to locate the source or sources of the heavy
load of high oxygen demanding materials that were entering
the Hagerstown treatment plant during the early morning
hours, week days.
(2) Twenty-four-hour composite samples of the plant influent
collected each day of a seven-day period, which included
week day and weekend wastewater representation.
(3) Twenty-four-hour composite samples of the plant influent,
primary effluent, and final effluent collected at random
times, weekly.
The chromatograph obtained on the grab samples of the wastewaters
that were essentially industrial in nature (groups (1) samples)
exhibited, as a whole, some 19 different peaks exclusive of the
water and air peaks common to all chromatograms made on aqueous
samples. It was evident from an analysis of the data that
particular peaks or pollutants could be associated with parti-
cular industries.
37
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Chromatograms of the group (2) samples, the 24-hour composites
of the plant influent, distinctly showed at least six of the
peaks found in the chromatograms of the group (1) samples. One
especially predominate peak was traceable to wastes discharged
by a textile dyeing and printing plant by correlation with the
chromatographic information obtained on the group (1) samples.
The other major peaks were attributable to the textile dyeing
and printing plant also, and to a creamery. Other constituents
appeared in the group (2) composites that were not detected in
the group (1) samples; however, they were relatively minor.
On the other hand, certain of the chromatographically detected
components of the group (1) samples were not found in the group
(2) samples, perhaps as a result of being reduced in concentra-
tion below G-C detection limits by dilution in the sewer system
and by sample compositing. The group (2) samples collected on
week days contained a greater number and larger amounts of
chromatographable materials than did the group (2) samples
collected on the weekend,as had been expected.
The chromatograms of the 24-hour composite samples of plant
influent, primary effluent, and final effluent (group (3)
samples) showed some of the same peaks as the chromatograms
of the samples of groups (1) and (2). In following the chroma-
tograms of the group (3) samples from plant influent to effluent,
it was plainly evident that there were gradual decreases in the
areas under some of the peaks, indicating decreases in the
quantities of the wastewater components yielding the peaks,
and certain influent chromatogram peaks were completely absent
in the chromatograms of the final effluent samples. These de-
creases and disappearances may have been due to one or a
combination of the following factors:
(1) the pollutants were actually degraded in the treatment
plant,
(2) the pollutants were diluted in concentration as they
passed through the plant,
(3) the pollutants, being volatile, were swept from the
wastewater by aeration, and
(4) the pollutants were absorbed by suspended solids.
B. Survey of Industrial Plant
1. Introduction
Beginning shortly after the project was initiated, a limited survey
of a select number of industrial plants located within the city of „
Hagerstown was conducted to discover the types and amounts of wastes
38
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these plants were discharging into the city's sanitary sewerage
system. Since it was felt at the beginning of the project that
the textile dyeing plants wastes and the wastes from the metal
finishing and plating plants were imposing the greatest diffi-
culties on the treatment plant, the textile dyeing and metal
finishing and plating plants were the primary target of the
survey effort.
Preparatory to the effort, a cursory literature study of modern
textile dyeing and metal finishing and plating practices was
carried out to familiarize the survey personnel with these
practices. Also, a list of the various textile dyeing plants
as well as other types of industrial plants utilizing the city's
sewerage system was compiled, and waste-discharge-questionnaire-
and-record booklets for issuance to the industries were prepared.
From the compiled list of industries, key industries were selected
to be surveyed. These industries then were sent a letter from the
Mayor's office, explaining in general the project and in particular
the planned survey and requesting the cooperation—in fact, the
active participation—of these industries in the investigatory
effort. These industries were screened further through actual
in-plant visits by members of the project team; and, on the basis
of plant size, nature of the wastes discharged, and the volumes
of the discharges, nine of the candidate industries were finally
chosen for the complete survey, the rest being dropped from further
consideration.
Following the selection of the nine industries, top management
personnel in each of the industries were given copies of the
questionnaire—record booklets with instruction for their completion
and the in-depth survey of these industries were begun. The purpose
of the record booklets was to obtain in written form from each in-
dustry project pertinent information on plant practices and to
establish in each industry a program of recording daily over the
survey period the types and amounts of chemicals consumed and
materials wasted during each day of operation. A set of the forms
contained in the booklets may be found in the appendices of this
report.
Over the survey period, which initially was allotted sixteen weeks
of project time, a series of visits were paid by various members of
the project team to each of\the industries. During these visits,
data recorded in the booklets were collected; plant operations were
reviewed; supplemental information on plant waste disposal practices
were secured; and, to promote the spirit of cooperation, questions
about the project from plant personnel were encouraged and, when
raised, openly answered. Without exception, each industry contacted
responded to the survey undertaking with expressions of interest in
the project and of willingness to participate in the survey. The
favorable responses are attributed in part to the fine public relations
39
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efforts conducted by the city in regard to the project and the
realization by the industries of the real necessity for the
project, including the industrial survey.
Industries Surveyed and Survey Data Obtained
The industries surveyed and the survey data obtained are
presented below:
(a) Mack Trucks, Inc. - 1999 Pennsylvania Avenue, Hagerstown, Md.
This plant of Mack Trucks, Inc., employ approximately 3500
persons, working in three shifts, seven days a week. It has
about 1.02 million square feet of manufacturing area and
produces the complete power train—engines and transmissions—
for heavy duty trucks.
Prior to the project, this plant reportedly, was responsible
for several sizeable oil dumps into the city's sewerage system
that resulted in large quantities of oil reaching the municipal
sewage treatment plant and severely impairing the performance
of the treatment plant for periods of several days. However,
just before the project was begun, the company installed and
placed into operation two No. 150 Josam Oil Interceptors to
prevent further such incidents.
The basic manufacturing operations of the Mack plant are cutting
and heat treatment of metal engine parts. No metal pickling or
plating operations are carried out. The oil necessary for the
cutting operations is prepared and stored at a single location
in the plant and pumped from that location through a piping
system to the various metal cutting machines in the plant.
Waste oils from the cutting machines are collected in four
sumps situated strategically throughout the plant and then
pumped from the sumps into a single waste oil storage tank.
Ultimately, the waste oils are pumped from the storage tank
into a tank truck for reclamation or disposal elsewhere.
Machined engine parts are washed free of excess oils in large
industrial washers. There are 52 such washers in the plant and
they use Mack 326 and 328 Alkaline Cleaners in the concentration
of 1 to 3 oz of the alkaline base material to one gallon of water
with approximately 180 to 360 Ibs of the Mack 326 Cleaner and
700 to 1500 Ibs of the Mack 328 Cleaner being consumed each week.
Once a week, generally between midnight and 8:00 a.m., the
cleaner solutions are discharged from the washers into the city's
sanitary sewerage system. One third of the industrial washers
are equipped with oil skimmers; the rest have drip drags which
aid reportedly in oil removal.
40
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The plant contains two recirculating cooling water systems, the
waters of which are treated for corrosion control with chromate
(25 to 50 mg/1), sulfuric acid and sodium polyacrylate. Approxi-
mately, 70 Ibs of chromate (Dearborn 533), 2.6 Ibs of 66° Be
sulfuric acid and 9 gallons of sodium polyacrylate are used
weekly in the treatment of the waters. In addition, the cooling
waters are also treated with sodium pentachlorophenate (Dearborn
711), a slimicide, of which about 21 Ibs are used weekly. The
"blow down" from these systems is set at approximately 2%, which
amounts to a constant flow of about 15 gpm from one system and
10 gpm from the other. These blow-down discharges enter the
city's sanitary sewerage system directly. However, any excess
cooling waters from the boilers that supply hot water to the
previously mentioned industrial washers are discharged into
the storm drain system of the plant.
In the plant, certain machined metal parts undergo heat treatment
for case hardening. Two different heat treatment processes are
used. In one process parts undergo carburizing in a furnace.
Some of these parts, immediately after removal from the carburi-
zing furnace, are automatically oil quenched, then rinsed with
water, which subsequently is wasted to the city's sewerage
system. Other parts, after removal from the carburizing furnace,
are held in a die press to hold their shapes until sufficiently
cool, then subjected to an oil quench and finally a water quench.
There are about one dozen water-quench-bath vessels in the plant
for this process. These are 5' x 5' x 2.5' in size and, depend-
ing on the-degree to which they are used, are generally dumped
once a month into the sanitary sewerage system.
In the second heat treatment process, which involves liquid
carburizing with the use of "Cyanobrik" (97% sodium cyanide
briquettes), there are three baths; namely: a molten salt
bath (Park Chemical Company "Nu-Sal", neutral salt, m.p.
1230°F), an electrolytic salt quench (Park Chemical Company
"Thermo-Quench," m.p. 288°F), and a salt bath water quency
(AJEM-33-S). The salt bath water quench is contained in only
one vessel, whose dimensions are 2' x 2' x 1.5'. There is a
continuous overflow from this vessel to the drain and the
sanitary sewerage system; this overflow amounts to about 25
gallons per day. From 620 to 920 Ibs of the AJEM-33-S material
is used weekly to maintain the salt content of the quench bath.
Concerned about cyanide being introduced into the city's sewerage
system as a result of the above heat treatment process, the
project team sampled and tested the wastewater discharges of>the
Mack plant during the survey of the plant. These tests revealed
no significant levels of cyanide in the discharges.
41
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There is a research and development and engine testing area in
the plant where engines are assembled, run, studied and dis-
assembled. The floor drains in this area lead to the previously
mentioned oil separators. Waste oils recovered by the separators
are pumped into one of two waste oil storage tanks. One tank_is
for oils to be carted away; the other is for oils to be reclaimed.
Waters from the separators are pumped into the sanitary sewerage
system.
The plant has its own storm drain system, which surrounds the
entire Mack facility; and, this system discharges into an
earthen dam, which can store nearly 1.5 million gallons of
stormwater. This drain system is not connected in any way to
the city's sewerage system.
The plant wastes to the city's sewerage system an estimated
400,000 gallons of water daily.
(b) Pangborn Corporation - Pangborn Boulevard, Hagerstown, Md.
The Pangborn Corporation is a wholly-owned subsidiary of the
Corborundum Company, Niagara Falls, New York. The Hagerstown
facilities of the corporation employ more than 1200 people and
are devoted to both engineering and manufacture of complete
systems for cleaning, deburring, descaling, peening, etching
and finishing the surfaces of metals and metal components and
complete systems for industrial air pollution control. The
manufacturing facilities consist of foundry, machine-shop,
metal-working, wood-working, and assembly plants.
Essentially all manufacturing operations performed in the
Hagerstown facilities of the Pangborn Corporation are "dry."
Treatment of metals is done solely mechanically by means of the
company's own devices--"Rotoblast" and air blast machines--
consequently there are no chemical treatments, such as pickling,
with highly acidic or alkaline liquid waste. In some metal
cutting and drilling operations, oils and other lubricants are
used; but, these substances are employed in only limited
quantities; and, when they are spent, they are disposed of by
being poured over the gravel bed of the railroad spur that
serves the Pangborn complex. This method of disposal is practiced
primarily for weed control and, reportedly, there are never enough
spent lubricants for this purpose.
There are several air scrubbers for dust control located in
various sections of the Pangborn facilities. The waters in
these units are continuously recirculated (with evaporation
losses continually replaced), and these waters are never
discharged to the city's sewerage system. The sludges of fine
particulate matter that collect in the scrubbers are continuously
42
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and automatically removed from the scrubbers by mechanical
conveyor systems and deposited in drums, which, when full,
are carted away from the Pangborn site for ultimate disposal
of the sludges elsewhere.
Because all the manufacturing operations of the Pangborn
facilities in Hagerstown are, in fact, dry, these facilities
do not discharge any "industrial wastewaters" of any sort
into the city's sewerage system.
(c) Potomac Dye and Print Corporation - 1000 Florida Avenue,
Hagerstown, Maryland.
The Florida Avenue plant of the Potomac Dye and Print Corporation
is one of two textile dyeing plants owned by this corporation in
the City of Hagerstown. The second plant is located on Franklin
Avenue in the city and its operations are reviewed subsequently.
The Florida Avenue plant employs about 65 people and occupies
approximately 51000 square feet of space.
Primarily, the plant roller prints synthetic fabrics with a water
phase print system. The print vehicle is mineral spirits (Varsol)
in water emulsion; and, all dye colors, emulsions, and resins used
in the print colors are water soluble until they are dried and
cured on the printed fabric in the printing process. Varsol
comprises about 50% of any dye mixture.
In addition to several roller type printing machines, which
incidentally use copper rollers that are etched with the print
designs elsewhere, the plant contains four dye jigs, one dye
box (2000-gallon capacity) and a large fabric washer with a
stream dryer. The four dye jigs and the dye box are used for
cloth "boil-off" and the washer-dryer for washing and drying
back greige (cotton duck) and print cloth.
Typically, about 15500 yards of back greige and 37000 yards of
fabric to be printed and washed and dried each day. Nearly 90%
of the wastewaters discharged by the printing plant in the city's
sewerage system are generated by the washer-dryer. In the
washing process, only two chemicals are used—sodium pyrophosphate
and sodium metasilicate. Approximately, 162 Ibs and 49 Ibs of
these chemicals, respectively, are employed daily.
The entire plant consumes a total of about 112000 gallons of
water a day, of which about 102000 gallons are ultimately
discharged to the sewer and 10000 gallons are lost by evapora-
tion in the cloth washing and drying operation.
43
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Table 1. CHEMICALS AND DYESTUFFS CONSUMED BY THE FLORIDA AVENUE PLANT
OF THE POTOMAC DYE AND PRINTING CORPORATION
Chemical
Chemical Division
Press Cakes (all colors)
Monsanto Serox DJ (Alkylaryl
Polyoxyethyle Ether)
Antifoam B
Pontamine White BT
Potassium Tripolyphosphate
Titanium Titanox A-WD
(Titanium Dioxide)
Methacel
China Clay
Rohm & Haas Rhoplex HA-8
Purpose
Pigments for Color Dispersions
Emulsifier
Anti foaming Agent
Optical Bleach
Dispersing Agent
Titanium Pigment
Thickener
Filler
Fabric Binder
Quantity
In 84 Days
8700 Ibs
1870 Ibs
485 Ibs
54 Ibs
46 Ibs
2700 Ibs
2500 Ibs
2410 Ibs
3875 Ibs
Consumed
Per Day
_ _ m.
___
(Acrylic Emulsion)
-------
Table 1. continued
Chemical
Purpose
Quantity Consumed
In 84 Days
Per Day
-ts>
on
Mineral Spirits (Varsol)
Dow Latex 881
Polyacrylamide
Polyacrylate
Sodium Lauryl Sulfate
Monsanto Lytron 822
Aqua Ammonia
Butylated Mel amine
Dipentene
Monoethanolamine
Thickener L
RWA 325
Diethylene Glycol
Solvent
Latex Binder
Dispersing Agent
Dispersing Agent
Wetting Agent
Emulsifier
Cleanser
Fabric Finish
Solvent
Dispersing Agent
Thickener
Dispersing Agent
Dye Solvent
49000 Ibs
9000 Ibs
100 Ibs
80 Ibs
4015 Ibs
610 Ibs
2955 Ibs
4325 Ibs
780 Ibs
95 Ibs
2800 Ibs
649 Ibs
435 Ibs
-------
Table 1. continued
CT>
Chemical
Purpose
Quantity Consumed
In 84 Days
Per Day
Print Division
Rohm & Haas Paraplex G60
Dow Antiform B
Ammonium Sulfate
Mineral Spirits (Varsol)
Dow Latex 881
Natural Latex
Trimethylol Mel ami ne
Acetone
Back Greige and Print Cloth
Sodium Pyrophosphate
Sodi urn Metasi 1 i cate
Print Softener
Anti forming Agent
Catalyst
Solvent
Binder
Finishing
Fabric Treatment
Solvent
Washing
Cleanser
Cleanser
1090 Ibs
1600 Ibs
500 Ibs
2100 Ibs
20800 Ibs
7300 Ibs
920 Ibs
21 Ibs
13600 Ibs
8300 Ibs
13 Ibs
191 Ibs
6 Ibs
250 Ibs
247 Ibs
87 Ibs
11 Ibs
1/4 Ib
162 Ibs
99 Ibs
-------
The plant has nearly one floor drain for every 500 square feet
of floor space. These drains lead to three below-the-floor
sumps whose effluent lines eventually join into one line which
empties into the city's sewerage system.
The plant has its own laboratory (referred to as the "Chemical
Division" of the corporation) for preparing the color cakes and
color dispersions used in the textile printing operations of
the plant as well as plants of other companies. In general,
it is not practical to give typical values for the quantities
of chemicals and dyestuffs utilized in the preparation of the
colors and in the textile printing operations of the plant on
a daily basis since the printing operations vary considerably
from day to day with respect to the types and amount of fabrics
printed and colors used. However, the amounts of the various
chemical and dyestuffs consumed in all plant operations over
the 83 plant operating days that comprised the plant survey
period were recorded and are tabulated on the next page; and,
in those instances, where daily consumption values are meaning-
ful these date are given also.
(d) Potomac Dye and Print Corporation - 367 East Franklin Street,
Hagerstown, Maryland.
This is the second of the two plants of the Potomac Dye and
Print Corporation in the City of Hagerstown; and, it has about
69 employees.
The plant dyes synthetic fabrics (materials of nylon, polyester,
etc.), filaments or spun yarns and some cotton goods. In addition,
it finishes all the cloth that is dyed in the plant and all the
cloth that is printed in the Florida Avenue Plant.
The "dyeing operations" of the plant consist of the following
cloth treatments:
(1) Washing with plain water
(2) Bleaching with hydrogen peroxide and "optical bleaches"
(3) Boil-off with detergents and alkalies
(4) Dyeing with either dispersed, acetate or direct colors
The application of finishes to cloth is done in baths which may
contain water and water solutions of water repellents, resins,
soaps, starch, urea, dullers and softeners. A list of the
chemicals used during the survey period in both the dyeing and
finishing processes is presented in Table 2 on the following
page.
47
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Table 2. CHEMICALS AND DYESTUFFS CONSUMED BY THE FRANKLIN STREET PLANT
'OF THE POTOMAC DYE AND PRINTING CORPORATION
Chemical
Dyeing
Disperse Acetate Dyes
Neozyme L (Enzyme)
Zinc Sulfoxalate
Hydrogen Peroxide (35%)
Sodium Hypochlorite
Mineral Spirits (Emulsion
Purpose
Dyes
Desizer
Stripper
Bleach
Machine Cleaner, Bleach
Solvent
Quantity
In 84 Days
3862 Ibs
10400 Ibs
650 Ibs
7950 Ibs
900 gals
3370 gals
Consumed
Per Day
46 Ibs
124 Ibs
8 Ibs
93 Ibs
11 gals
40 gals
Form)
Rock Salt (Sat'd. Brine
Solution)
Wintergreen Oil (Methyl
Sal icylate
Trisodium Phosphate
Direct Viscose and Cotton
Dyes
Dyeing
Carrier
Sequestrant
Dyes
88100 Ibs
115 Ibs
44000 Ibs
3044 Ibs
1045 Ibs
1 Ib
524 Ibs
36 Ibs
-------
Table 2. continued
10
Chemical
Ammonia Solution
Sodium Silicate
Muriatic Acid (Hydrochloric
Acid)
Acetic Acid
Sodium Nitrite
Proctor & Gamble 01 ate Flakes
Sodium Bisulfite
Purpose
Cleanser
Detergent
Acid
Acid
Dyeing Assistant
Detergent
Reducing Agent (Anticlor)
Quantity
In 84 Days
2333 Ibs
8522 Ibs
224 Ibs
,6060 Ibs
1431 Ibs
2225 Ibs
50 Ibs
Consumed
Per Day
28 Ibs
101 Ibs
3 Ibs
72 Ibs
17 Ibs
27 Ibs
1/2 Ib
Soda Ash (Sodium Carbonate)
Monsanto Sterox CD
(Polyoxyethylene Ether)
Dow Versene 100 (EDTA)
Finishing
Secondary Butyl Alcohol
Dow Antifoam B
Detergent
Detergent
Sequestrant
Solvent
Antifoaming Agent
2494 Ibs
900 Ibs
2313 Ibs
1080 Ibs
30 Ibs
11 Ibs
28 Ibs
12 Ibs
-------
Table 2. continued
in
o
Chemical
Amour Arquad 2HT-75 (Quarternary
Ammonium Compound)
American Cyanamide Dicyandi amide
American Cyanamide Resin M3
(Trimethyol Mel ami ne)
American Cyanamide Resin 23 Spec.
Dow Dowicide A (Sodium o-Phenyl-
phenate Tetrahydrate)
Magnesium Chloride
White Bentonite (Natural
Aluminum Silicate)
Gum Tragacanth (Natural Gum)
Monsanto Mersize (Resin Soup)
Monsanto Syton DS (Colloidal
Purpose
Softener
Buffer for Resins
Fabric Treatment
Fabric Treatment
Preservative
Catalyst
Duller
Finishing
Detergent
Antislip Finish
Quantity
In 84 Days
2779 Ibs
2650 Ibs
21450 Ibs
6585 Ibs
50 Ibs
2350 Ibs
550 Ibs
318 Ibs
4000 Ibs
2200 Ibs
Consumed
Per Day
33 Ibs
32 Ibs
255 Ibs
78 Ibs
1/2 Ib
28 Ibs
6 Ibs
4 Ibs
48 Ibs
262 Ibs
Silica)
Monsanto Sterox DJ (Alkylaryl
Polyoxyethylene Ether)
Detergent
5644 Ibs
67 Ibs
-------
Table 2. continued
tn
Chemical
Sodium Formate
Titanium Pigment Corp.
Purpose
Gas Fading Inhibitor
External Delustrant
Quantity Consumed
In 84 Days Per Day
16500 Ibs 196 IDS
200 Ibs 2 Ibs
Titanox A-WD (Titanium
Diox-ide)
Urea
Aluminum Acetate
Glacial Acetic Acid
Dupont Zelon S (Aqeous Dispersion
of Polymer Wax)
National Starch Korfilm 50
(Starch)
American Cyanamid Aerotex
Reactant 1 (Cellulose
Reactant)
American Cyanamid Cyanolube
Softener 40 (Polyethylene
Emulsion)
American Cyanamid Cyanolube
Softener SB!00
Weighter (with starch) 11400 Ibs
Water Repellent 350 Ibs
Water Repellent Preparative 330 Ibs
Water Repellent 1117 Ibs
Finishing 30400 Ibs
Wrinkle Recovery 13387 Ibs
Softener (Resin Finishes) 8000 Ibs
Softener 2133 Ibs
136 Ibs
4 Ibs
4 Ibs
13 Ibs
361 Ibs
159 Ibs
95 Ibs
25 Ibs
-------
During a typical operating day, the plant dyes some 78500 yards
of cloth and finishes some 109300 yards, utilizing in these
processes about 130000 gallons of water. Of this volume of
water consumed daily, about 41000 gallons are lost through
evaporation and 91000 gallons are discharged into the city's
sanitary sewerage system.
Before the discharged process wastewaters reach the sewer,
however, they are funneled by the floor drain system of the
plant into an 8-foot diameter by 15-foot deep holding tank.
Reportedly, this tank is cleaned out every two months by a
private disposal company.
(e) Associated Ribbon Works - 655 N. Prospect St., Hagerstown, Md.
The Associated Ribbon Works employs 33 persons and engages in
the dyeing of ribbon. The ribbon materials processed by the
plant are generally made of rayon, acetate, cotton-acetate,
rayon-acetate and nylon and vary in widths from 1/4 inch to
5 inches.
Ribbon is handled in skein form. Before being actually dyed,
it is cleaned (scoured) with hot alkalies and detergents,
bleached in sodium hypochlorite solution, water rinsed and then
treated with an antichlor. Some of the ribbon so processed is
not subsequently dyed but is retained as white stock. Most of
the ribbon, however, is dyed, and aniline type dyestuffs are
used in the dyeing process. These dyes are applied to the
ribbon fabric in boiling liquors that contain in addition to
the dyes used during the period this industry was surveyed can
be found in the table given on the following page. The plant
does not do any ribbon finishing; instead, it sends the ribbon
it has processed to the Maryland Ribbon Company plant on
Willow Circle in Hagerstown for this treatment.
The day-to-day dyeing operations are not carried out in accordance
with any regular schedule. Consequently, water useage varies
between 55000 to 102000 gallons per work day. Moreover, all
processing is done on a batch basis with spent scouring,
bleaching, rinsing and dyeing baths never being regenerated;
each bath is dumped immediately after each bath operation is
completed. The spent liquors are discharged into floor trenches
which convey the waste to a single drain line which discharges
directly into the city's sewerage system.
52
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Table 3. CHEMICALS AND DYES USED BY THE ASSOCIATED RIBBON WORKS
Chemical
Purpose
Average Daily
Useage
Dyes
GAP Igepon T-5 (Sodium
N-methyl-N-oleoyl
taurate)
Sodium Pyrophosphate
Laurel Vidol Flake
Soap (Low Titre Soap)
Laurel Laurel 65-3
Rumford Quadrofos
(Sodium Tetra-
phosphate)
Glaubers Salt (Sodium
Sulfate Decahydrate)
Soda Ash (Sodium
Carbonate)
Sodium Bicarbonate
Sodium Hypochlorite
Solution
Sulfuric Acid, 66° Be
Sodium Bisulfite
Althouse Resamide Extra
Althouse Resogen FWL
Brine (Sat'd. Sodium
Chloride Solution)
Acetic Acid
Dyeing 32 IDS
Leveling & Dispersing 13 Ibs
Agent
Water Conditioner 17 Ibs
Detergent & Dispersing Agent 10 Ibs
Leveling Agent 13 Ibs
Water Conditioner 7 Ibs
Exhausting Dyes onto 71 Ibs
Fabric
Cleaning & Dyeing 100 Ibs
Dyeing Catalyst 4 Ibs
Cotton Bleach 20 Ibs
Neutralization in Bleaching 8 Ibs
Reducing Agent (Antichlor) 6 Ibs
Stain Prevention 0.5 Ibs
Making Dyes Washable 0.5 Ibs
Direct Dyeing 57 gals
Acidifying 7 Ibs
53
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Table 3. continued
Chemical
Purpose
Average Daily
Useage
Ciba Albatex BD (Sodium
m-Nitrobenzone
sulfonate)
TNA-5 Salt (Sodium
Chloride)
Althouse Metachloron
Formaldehyde
Caustic Soda (Sodium
Hydroxide)
GAP Dizopon SS837
Royce Vatrolite (Sodium
Hydrosulfite)
Ammonia Sulfate
Tanatex Gas Inhibitor
A (Neutral Alkylamine
Derivative)
Muriatic Acid, 20%
Hydrochloric Acid)
Sandoz Revatol S
(Sodium m-Nitrobenzene
sulfonate)
Royce Parolite (Zinc
Formaldehyde Sulfoxa-
late)
01 in Mathieson Textone
(Sodium Chlorite)
Leveling Agent 4 Ibs
Direct Dyeing 277 Ibs
Color Migration Pre- 4 Ibs
ventative
Making Dyes Washable 3 Ibs
Cleaning Agent 11 Ibs
Leveling Agent 0.3 Ibs
Stripping Agent 7 Ibs
Acidifying in Dyeing 2 Ibs
Atmospheric Fading 1 Ib
Preventative
Acidifying (Resin Removal) 8 Ibs
Leveling Agent 1 Ib
Stripping Agent 0.5 Ib
Stripping Agent (Nylon) 0.1 Ib
54
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Table 3. continued
Chemical
Purpose
Average Daily
Useage
Tanatex X-Tan Special C
(Sodium Alkyl Oleate
Sulfonate)
Oxalic Acid
Aqueous Ammonia, 29%
Sandoz Sandofix WE-51
(Cationic Resinous
Compound)
Corrosion Control
(w/Terbine)
Rust Stain Removal
Acid Neutralization
Fixation of Colors
0.3 Ib
0.1 Ib
0.2 Ib
3 Ibs
55
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(f) Maryland Ribbon Company - 857 Willow Circle, Hagerstown, Md.
The Hagerstown plant of the Maryland Ribbon Company both
finishes and packages ribbon and related narrow fabrics
for marketing. Most of the 225 employees of the plant are
engaged in packaging and shipping of ribbon—operations,
which do not involve the use of any chemicals of any nature
that may ultimately end up in the sanitary sewerage system
of the city. About only seven plant employees are assigned
to the ribbon finishing operations of the plant.
For the main part, ribbon finishing is done automatically
by machines which pass the ribbon to be treated through
small, narrow baths of water solutions and suspensions of
finishing materials, namely, resins and water soluble
starches. Most of these solutions and suspensions are absorbed
by the fabrics in the treatment process and as the ribbons are
dried by the steam dryer associated with the finishing machines
the water of the solutions and suspensions is of course driven
off by evaporation. As a result, the plant generates a minimal
amount of liquid waste from its finishing operations. In fact,
it discharges about only 45 gallons of process water per day
while it consumes about 250 gallons of process water daily.
The waste finishing liquors are discharged to the city sewer
only between machine runs (and at the end of each work day
since the contents of the finishing baths are not held over
from one working day to the next) when the finishing baths
are flushed free of their contents.
The plant uses only a limited number of substances in its ribbon
finishing operations and these substances are summarized in the
table on the following page.
»
(g) Victor Hosiery - 775 Frederick Street, Hagerstown, Md.
Victor Hosiery, which has about 30 employees, both manufactures
(weaves) and dyes nylon stockings and panty hose for women.
Only the dyeing and associated scouring and stripping processes
of the plant yield any industrial wastewaters. The volume of
wastewater resulting from these operations amounts to approxi-
mately 1024 gallons each working day. These waste enter
directly into the city's sewerage system.
The plant dyes nearly 10000 dozen pieces of hosiery weekly.
Dyeing as well as scouring and stripping is done in batches
(500 dozen pieces per bath) and carried out in seven barrel
type dyeing machines. Upon completion of any of these
operations, the liquid contents of the dyeing machines being
56
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used are dumped. Generally, the actual scouring and stripping
operations are followed immediately by one or two plain water
rinses that are effected in the dyeing machines. The spent
rinse waters are of course released to the city's sewer, also.
During the 20-week period over which the Victor Hosiery plant
was surveyed, stripping, which involves the use of sodium
hydrosulfite, was generally performed only once or twice a
week although there were some weeks in which stripping was
not done at all or as frequently as four times (days) a week.
The plant uses a variety of chemicals and dyestuffs in its
dyeing operations. These materials and the amounts of them
that are consumed during a typical work day are given in the
table on the next page. As noted in the table, a few of these
listed materials are used only very infrequently.
(h) W. H. Reisner Manufacturing Company, Inc. - 240 N. Prospect
Street, Hagerstown, Maryland.
This industry employs 73 people and produces pipe organ supplies,
screw machine products and, for the U. S. Navy, radar plotting
boards. It is housed in two separate buildings, which are located
adjacent to each other and are considered by the company as two
separate and distinct manufacturing plants.
The manufacturing operations of the industry are essentially
metal working and metal treatment although the industry does
do some woodworking, cabinet making and electrical wiring in
addition. The primary metal operations of the industry are:
die casting (zinc), press forming and blanking, heliarc welding
of aluminum sheets and extrusions, chemical cleaning of metal
parts, chemical preparation of metal surfaces for painting and
plating and the painting and plating of metal products.
Chemical cleaning and chemical preparation for painting and
plating of metal surfaces and the actual plating of metals are
essentially the only industrial processes of the Reisner
Manufacturing Company that generate wastes that are eventually
discharged to the city's sewerage system. The industry consumes
on the average about 10000 gallons of city water per day. Of
this amount, approximately 750 gallons are used for sanitary
purposes and 9250 gallons for industrial purposes. Almost
all the water employed for industrial reasons is used for
cooling various plant equipment; namely, two compressors, a
die caster, a spot welder, a heliarc welder and a vapor
degreaser. The cooling waters from the heliarc welder and
vapor degreaser are passed through the hot water rinse tanks
of the metal cleaning and plating operations. The overflow
from the rinse tanks and the cooling waters from the plant
57
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Table 4. CHEMICAL USED BY VICTOR HOSIERY COMPANY
Chemical
Geigy Cycoluce Yellow G
Textile Chemical
Cellutate Brilliant
Blue B Sepia
Geigy Setacyl Scarlet
RNA Sepia
Osco Chemical Auto Dye
63-50
GAP Celliton Orange GRA
Geigy Erio Black J
Geigy Tinopal WHN Liquid
Textile Chemical Assoc.
Fascadye 201 LF
HyChem Res i lube T-5
HyChem Migratex 39
Caustic Soda (Sodium
Purpose
Dye
Dye
Dye
Dye
Dye
Dye
Dye
Detergent (Scouring)
Finishing
Scouring
Scouring
Average Daily
Useage
0.5 Ib
0.5 Ib
0.4 Ib
35 Ibs
3 grams
0.2 Ib
0.1 Ib
7 Ibs
1 Ib
1 Ib
1 Ib
Hydroxide)
Royce Sodium Hydro-
sulfite
Asco Chemical Oscotol 300
Scholler Brothers Allo-
Scour
Laurel Products Vidol
Soap Flakes
Stripping
Water Treatment
Scouring
Detergent
1 Ib
2 Ibs
(See Note 1 below)
(See Note 2 below)
58
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Table 4- continued
Average Daily
Chemical Purpose Useage
Soda Ash (Sodium Scouring 0.2 Ib
Carbonate)
Geigy Alrosol CS Detergent (Scouring) 0.1 Ib
(Fatty Acid Amine
Condensate)
Notes: 1. Allo-Scour was used on only two days during the 20-week
period over which chemical useage data on Victor Hosiery
was collected and on each of these days the amount of
material used was only 0.5 Ib.
2. Vidol Soap Flakes was used on only three days during the
20-week survey period and on these three days the useage
was only 1, 3 and 2 Ibs, respectively.
3. A total of only 15 grams of Celliton Fast Pink FF 3BA
were used during the 20 week survey period.
59
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TABLE 5. DAILY CHEMICAL USEAQE OF THE MARYLAND RIBBON COMPANY
Chemical
Purpose
Amount Used
Daily
Rohn & Haas Rhonite
R-l (Urea-
Formaldehyde Resin)
Rohm & Haas Catalyst
H-7 (Zinc Complex)
Althouse Polyanthrene
KS
A. E. Staley
Solvitose H
(Potato Starch-
Ether)
Colloids Vicol 175
Vinyl Acetate
Copolymer)
Wetfastness & Shrinkage
Control
U-F Resin Catalyst
Wetfastness
Finish
106 IDS
15 Ibs
14 Ibs
56 Ibs
Finish
47 Ibs
60
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equipment other than the hell arc welder and vapor degreaser
are wasted into the city's storm sewer system. However, only
the air compressors operate continuously and, consequently, use
and discharge water to the sewer. The welding, cleaning and
plating operations are performed on a rather irregular schedule
depending, of course, on the work load of the industry and may
on some days be carried out not at all or for only a few hours.
Because of the irregularity of the metal cleaning and plating
operations and the rather small amounts in which many of the
chemicals employed in these operations are used, it was
difficult to obtain meaningful typical chemical useage data
on the industry even over the rather extended period of time
of the survey effort. Fortunately, however, the company
maintains from year to'year fairly accurate records of its
chemical purchases, and it made these records available to
the survey team. The table on the following page presents
data on the average amounts of chemicals used by the company
over a year, data based on both the company records and
direct findings of the survey.
3. An Extension of the Survey
(a) The Search for a Waste Source
None of the data gathered in the survey of the industrial plants
of the City of Hagerstown provided any explanation for the
occurrence of the high chemical and biochemical oxygen demands
that, as revealed during the baseline studies of the project,
were regularly exhibited by the wastewater flows reaching the
Hagerstown wastewater treatment plant during the early morning
hours on week days. Since it was felt by the members of the
project team that the wastes that created these high demands
were probably being discharged in the city's sewerage system
by a single industrial plant and since the wastes exerted
such a significant impact on the city's treatment plant and,.
of course, on the operational studies of the project, which,
at the close of the scheduled portion of the survey effort,
were well underway, it was decided that the source of these
wastes ought to be found to disclose the exact nature of the
wastes.
The plan exercised to locate the waste source was simply to
track the slug discharge back up the sewer line from the plant
until the point of discharge was found. Over several workdays,
grab samples of the wastewaters flowing in various sewer mains
serving the major sections of the city were collected hourly
over the time period of 11:00 p.m. to 7:00 a.m. and the oxygen
61
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Table 6. CHEMICAL AND MATERIALS USED BY THE
W. H. REISNER MANUFACTURING COMPANY
Chemical
Purpose
Amount Used
Yearly
Plant No. 1 ("Main Plant")
Wyandotte Nu-Vat (Hot
aqueous solution)
Wyandotte F-S
Nickel Sulfate
Nickel Chloride
Boric Acid
Zinc Cyanide
Sodium Cyanide
Sodium Hydroxide
Muriate Acid, 20° Be
Nitric Acid, 42° Be
Sulfuric Acid, 66° Be
Perchloroethylene
(tetrachloroethylene)
Plant No. 2
Oakite #160 (Hot
aqueous solution)
Metal Cleaning
Metal Electrocleaning
Nickel Electroplating
(Barrell plating)
Nickel Electroplating
(Barrel! plating)
Nickel Electroplating
(Barrell plating)
Zinc Electroplating
(Barrell plating)
Zinc Electroplating
(Barrell plating)
Zinc Electroplating
(Barrell plating)
Pre-plati ng.Etchi ng
Pre-plating Etching
Pre-plating Etching
Solvent (Vapor Degreaser)
Metal Cleaning
(See Note 1)
(See Note 2)
500 Ibs
100 Ibs
50 Ibs
250-300 Ibs
200-250 Ibs
150 Ibs
80 gals
14 gals
14 gals
330 gals (See
Note 3)
900 Ibs (See
Note 4)
62
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Table 6. continued
Amount Used
Chemical Purpose Yearly
Oakite #34 Deoxidizer 500 Ibs
Allied Iridite #14.2 Painting Pretreatment 20 Ibs
Notes: 1. Nu-Vat, a product of Wyandotte Chemical Corporation, is a
synthetic detergent preparation, which, reportedly con-
tains no cyanides, chromates or cresoles. It is used in
hot aqueous solution, 2 to 4 ounces in one gallon of water.
When metal cleaning is being carried out, the maximum
amount of Nu-Vat solution that is discharged to the
sanitary sewer per day is about 50 gallons. All discharges
are batch.
2. F-S, also a product of Wyandotte Chemical Corporation, is a
phosphate cleaner which is mixed with water in the propor-
tions of 6 to 10 ounces of F-S per gallon of water.
3. Every two months, about 4 gallons of perchloroethylene,
which is used as the solvent in the company's metal vapor
degreaser, are discharged to the sanitary sewerage system.
4. The tanks containing the Oakite #160 solutions are dumped
only once or twice a year, depending on their use, with the
liquid being discharged to the sanitary sewer and tank
sludges being hauled away.
63
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demand indices (GDI's) of the samples determined. In addition,
in order to confirm that the waste slug was indeed entering the
treatment plant on the mornings of the sewer main sampling,
grab samples of the plant influent were also collected hourly
over the early morning hours and their GDI's subsequently measured.
Prior to the initiation of sample collection in the source search
effort, time-of-flow measurements were made in the sewer lines to
establish the appropriate starting time of each sewerline samples
were not collected to late, i.e., after the slug of waste had
passed the selected sampling points. These measurements also
gave some feel for the residence time of wastewaters in the
different sewerline sections examined. They were made by in-
jecting dye (rhodamine B) into the sewage flow at various points
at the extremes of the sewerage system and then timing how long
it took for the dye to reach the treatment plant. The longest
flow time measured—1 hour and 55 minutes—occurred in the
extensive "north line" which serves the northern section of
the city, with the dye injection being made at the extreme
end of the line, at the Mack Truck plant. Flow times from
the extremes of other sewer lines—east, south and west—ran
about an hour or less. Therefore, it was concluded that an
11:00 p.m. starting time for each sampling period was sufficiently
early to catch the slug no matter where in the system samples were
collected.
By this sampling technique, it was discovered that the waste
with the high chemical oxygen demand was coming to the treatment
plant through the west line. Subsequently, intensive sampling
of this line was conducted over a period of a couple weeks, the
sampling crew moving up the line from one key manhole to the
next. As a result, the source of the potent wastes was isolated
and found to be a cheese plant belonging to the Breakstone Sugar
Creek Foods Division of the Kraftco Corporation.
(b) Breakstone Sugar Creek Foods Division, Kraftco Corporation -
500 McDowell Avenue, Hagerstown, Maryland.
Immediately after the Breakstone Foods plant was discovered to
be the source of the slug waste discharges of concern, it was
included in industrial survey effort of the project. As had
been done with the other industries surveyed, in-plant inspec-
tions were made of the industry by members of the project survey
team. Key personnel of the Breakstone Sugar Creek Food Division
upon learning of the inclusion of cheese plants in the survey
cooperated fully with.the survey team and supplied the team with
all requested plant operating data.
-------
The plant, which employs 26 persons, produces cottage cheese,
sour cream and sour dressing. In the plant, whole milk is
separated into cream and skim milk, which are then pasteurized.
The pasteurized skim milk is put in vats, a culture of lactic
acid bacteria "starter" is added to it, and the milk is incubated
until the curd is set (i.e., until a firm coagulum is formed).
The curd is then cut into small pieces and heated until the
desired amount of whey has been expelled from it and it
develops the texture sought. The whey is then drained off and
wasted and the curd washed. The washed curd is subsequently
pumped to blenders, which blend cream dressing into the curd.
From the blenders, the finished creamed cottage cheese is
packaged into containers of various sizes, placed into shipping
cartons and moved to refrigerated storage in preparation for
shipping.
The pasteurized cream is made into either sour cream, sour
dressing or sweet cream dressing. These products are packaged
separately or mixed with the cottage cheese curd.
At the end of a day's operation, or earlier when convenient or
necessary, all of the plant process equipment is washed with an
alkaline cleaner and sanitized with a chlorine solution; and,
as needed, mineral deposits in the equipment are dissolved away
by the use of diluted phosphoric acid solution. The various
chemicals employed in these operations and added to the boiler
waters (the blow-down fraction of which enters the city's sewerage
system) of the process heaters and the amounts of them consumed
per working day are given in the table on the next page.
Plant operations are shut down on Fridays and started up again
on Sundays. Cottage cheese whey is discharged to the city's
sewage system every week day, sometime between midnight and
4:00 a.m. The volume of whey discharged each time is about
7700 to 8000 gallons. The spent wash waters from the curd
washing operations, which immediately follows the dumping of
the whey, are also discharged to the city's sewerage system,
the discharge time occurring between 1:30 and 6:30 a.m. and
the discharge volume being about 23,000 to 26,000 gallons. On
Sundays, Mondays, Tuesdays, Wednesdays and Thursdays the total
volume of process water—which includes the cottage cheese
wash water, cooling and heating water, and equipment and plant
washdown water—that is used and discharged to the sewer daily
ranges from 120,000 to 140,000 gallons. On Fridays, process water
consumption drops to around 80,000 gallons; on Saturdays, to
about 10,000 gallons.
65
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Table 7. CHEMICALS AND OTHER SUBSTANCES USED IN PROCESSES
OF THE BREAKSTONE FOODS PLANT
Chemical
Purpose
Amount Used
Daily
Sodium Hypochlorite
Solution (6%)
Phosphoric Acid (75%)
Liquid Detergent
Manual Cleaner
All-Metal Recirculation
Cleaner
Hi-Alkaline Cleaner
Garrett Calahan 153
Garrett Calahan 101-CF
Garrett Adjunct SS-CAT
(Sodium Sulfite)
Sanitizing
Millstone Remover
Cleaning
Cleaning
Cleaning
Boiler Additive
Boiler Additive
Boiler Additive
Boiler Additive
30 gals
55 Ibs
3 qts
50 Ibs
30 Ibs
33 Ibs
7 Ibs
17 Ibs
2 Ibs
66
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tc) Pollutional Significance of Whey
In the dairy industry, th.e disposal of cheese whey—especially
whey resulting from the manufacture of cottage and cream cheese-
has always been a problem. Currently, about 22 billion pounds of
whey are produced each year in the United States and about one
half of this amount goes to waste. Therefore, the Breakstone
Foods plant in Hagerstown is not unique in its whey disposal
practices.
The magnitude of the load that whey places upon a sewage
treatment plant can be of course rather large depending on
the amount wasted since whey is very rich in readily biode-
gradeable organic substances. It is estimated that one thousand
gallons of whey discharged per day into a treatment plant imposes
a BOD loading on that plant equal to the domestic water loading
generated daily by 1800 people per day. Thus, in the case of
Breakstone Foods plant in Hagerstown, the 8000 gallons of whey
discharged per working day by the plant exerts a load on the
Hagerstown sewage treatment plant equivalent to the load
generated by 14400 people—or 41% of the city's population.
Moreover, the wasted curd wash waters of course-exert an
additional load. Obviously, the load resulting from the whey
discharge is relatively large; however, its impact on the
municipality's sewage treatment plant was heightened severely
because the whey was not released at a steady rate over a
24-hour period but batch discharged to reach the treatment
plant in hefty slugs.
(d) Recommended Remedial Action
Upon the conclusion of the survey of the Breakstone Foods
plant, the project staff advised city authorities that the
severity of the impact of the whey and wash-water discharges
on the treatment plant could be ameliorated greatly by having
the cheese plant install a simple waste flow equalization tank-
from which the waste could be bled into the city's sewerage
system over a 24-hour period. The city passed this recommenda-
tion on to the industry, which immediately responded by taking
steps to design and install an appropriate flow equalization
system. The project staff, however, requested that the
Breakstone Foods delay the installation of any equalization
systems until the project was completed to avoid a major change
in project baseline conditions while the project was still in
progress. This request was honored and no equalization system
was installed until after the operational studies of the project
67
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were concluded. When an equalization system was finally con-
structed and placed into operation, an immediate and marked
improvement in the performance of the sewage treatment plant
was observed by plant personnel.
68
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SECTION VI
STUDIES OF VARIOUS PRETREATMENT METHODS
A. Wastewater Analysis Schedule for Pretreatment Studies
Shortly after the wastewater analyses of the project baseline study
were completed and the data compiled and evaluated, a wastewater
sampling and testing schedule was prepared for the pretreatment
studies of project and submitted to FWQA for review and comment.
The schedule was rather ambitious in that it included many more
analyses than were originally considered in the project program
plan. Tests that were suggested by the findings of the baseline
study and that were felt would be of value to the pretreatment
studies were added to the original list of proposed analyses.
The final schedule, which was designed to meet the sampling and
testing requirements of each of the pretreatment studies, is
presented on the following pages. Generally, this schedule was
fairly well adhered to over the course of the studies.
B. Startup and Stabilization of the Project Facility
On January 27, 1970, the entire wastewater flow received by the
Hagerstown treatment plant was directed for the first time into
and through the pretreatment tanks of the project facility and
the diffused air system of the facility was put into service.
Over the following three months—February, March and April—the
preaeration of the raw sewage flow was continued to allow the
pretreatment tanks of the facility to "stabilize." Although the
project program plan called for a one-month stabilization period, -
which was felt to be sufficient, the initiation of the first pair
of pretreatment studies was delayed until certain uncompleted work
on the facility, the previously mentioned modifications of the
existing final settling tanks of plant Sections No. 1 and No. 2,
and the construction of the additional settling tank for these
plant sections were completed so that the treatment plant would be
fully operational. Throughout the three month period, tests were
performed on the influent and effluents of the pretreatment tanks
to follow the course of stabilization. Initially, effluent dis-
solved oxygen concentrations ranged between 7 and 8 mg 02/1;
however, towards the end of February, these concentrations began to
drop presumably as a result of the appearance of significant
biological growths on the walls of the tanks. By the middle
of March effluent dissolved oxygen concentrations were in the
range of 4 to 6 mg 02/1, where they remained until the facility
aeration rates were changed in preparation for the first pre-
treatment study task.
69
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Table 8. ANALYSIS SCHEDULE FOR THE OPERATIONAL STUDIES
Analysis
Ammonia & Organic
Nitrogen
Biochemical Oxygen
Demand
Chemical Oxygen
Demand
Chlorine Residual
Color
Type of Sample
24-hr
24-hr
24- hr
24-hr
Grab
24- hr
Composite
Composite
Composite
Composite
Composite
Sampling
1,
7A
1,
7A
1,
7A
2B
2B
1,
7A
2A,
, &
2A,
, &
2A,
, &
, 3B
, 3B
2A,
, &
2B,
7B
2B,
7B
2B,
7B
, &
, &
2B,
7B
Points
3A, 3B,
3A, 3B,
3A, 3B,
7B
7B
3A, 3B,
Analysis
Frequency
Every
3 Days
Every
2 Days
Every
2 Days
Daily
Every 8 hrs
Hours
Every
Thursday
or Friday
Remarks
To be done concurrently
with COD's.
To be done concurrently
with BOD's, and on both
filtered and unfiltered
aliquots of samples from
points 7A & 7B.
To be done only during
pretreatment by chlorina
tion
Dissolved Oxygen
(In Situ Measure-
ment)
1, 2A, 2B, 3A, 3B,
4A11, 4A12, 4A21,
4A22, 4B, 5A13,
5A23, 6A1, 6A2, 6B,
7A, & 7B. Also head
and tail ends of all
wastewater tanks.
Daily, Week DO Meter measurements
Days
made in situ. DO at
points 1, 2A and 2B will
be measured continuously
by automated monitoring
system.
-------
Table 8. continued
Analysis
Type of Sample
Sampling Points
Analysis
Frequency
Remarks
Hydrogen Sulfide Grab
Mixed Liquor Micro- Grab
scopic Examination
Mixed Liquor Oxygen Grab
Uptake Rates
Mixed Liquor Suspended Grab
and Volatile Sus-
pended Solids
Ni trate
Nitrite
Oxidation-Reduction
Potentials
24-hr Composite
24-hr Composite
(In Situ Measure-
ment)
1, 2A, 2B, 3A, 3B, Daily, Week
7A & 7B Days
5A and 5B
4A12, 4B, 5A & 5B Once a Week
Every
Wednesday
4A12, 4A22, 4B, 5A1 Every
5A2, & 5B 2 Days
1, 2A, 2B, 3A, 3B,
7A, & 7B
1, 2A, 2B, 3A, 3B,
7A, & 7B
1, 2A, 2B, 3A, 3B,
4A, 4B, 5A, 5B, 6A,
6B, 7A, & 7B
Every
3 Days
Once a Week
Warburg respirometric
measurements.
Sampling point 8 to be
included during pre-
treatment by waste
activated sludge addi-
tion.
To be done every 2 days
on samples from points
1, 2A, 3A, and 7A during
pretreatment by NaN03
addition.
ORP's at points 1, 2A
and 2B will be measured
continuously by auto-
mated monitoring
system.
-------
Table 8. continued
Analysis
Type of Sample
Sampling Points
Analysis
Frequency
Remarks
PH
24-hr Composite
ro
Phosphate (Total)
Sulfate
"Sulfite" (Iodine
Oxidizable Sub-
stances)
Suspended Solids
Temperature
Volatile Organics
Wastewater Oxygen
Depletion Rates
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Composite
(In Situ Measure-
ment)
24-hr Composite
24-hr Composite
1, 2A, 2B, 3A, 3B,
7A, & 7B
1, 2A, 2B, 3A, 3B,
7A, & 7B
1, 7A, & 7B
1, 2A, 2B, 3A, 3B,
7A, & 7B
1, 3A, 3B, 7A & 7B
Same as for DO
1, 2A, 2B, 7A, &
7B
1, 2A, 2B, 3A, 3B,
7A, & 7B
Daily
Every
3 Days
Once a Week
Every
8 Hours
Daily
Daily
pH at points 1, 2A, &
2B will be measured
continuously by auto-
mated monitoring
system.
To be done turbidi-
metrically.
Analysis measures both
sulfide and sulfite
concentrations.
To be done concurrently
with DO determinations.
Every Thurs- To be done by means of
day or Friday gas chromatography.
Every Thurs- To be done by means of
day or Friday a DO meter.
-------
Table 8. continued
Analysis
Type of Sample
Sampling Points
Analysis
Frequency
Remarks
co
Digester Supernatant Grab
Liquor pH, Alkali-
nity, and Volatile
Acids
Mixed Liquor Grab
Settleable Solids
Primary and
Secondary digester
supernatant liquor
lines
4A, 4B, 5A, & 5B
Once a Week
Daily
Notes:
(1) Wastewater Monitoring System to be calibrated every Tuesday and Friday.
(2) Rates at which air, waste activated sludge, chlorine, ammonia, etc., are supplied to the
pretreatment tanks to be recorded daily.
(3) Rates at which air is supplied and at which sludge is returned to Sections 1 and 2 and to
Section 3 to be recorded daily.
(4) Wastewater flows to the entire treatment plant and*to Section 3 contact aeration tank are
recorded continuously by existing flow meters.
(5) The wastewaters at sampling points 1, 2A and 2B will be sampled continuously and proportional
to the flow by the automatic, refrigerated samplers of the project facility.
-------
Table 9. DESCRIPTION OF SAMPLING POINTS
Sampling Point Description
1 Influent "Y-Wall" Channel of Pretreatment Tanks
2A Effluent Channel of Pretreatment Tank A
2B Effluent Channel of Pretreatment Tank B
3A Effluent Channel of Primary Settling Tanks 1 & 2
3B Effluent Channel of Primary Settling Tank 3
4A11 Bay 1 of Section 1 Sludge Reaeration Tank
4A21 Bay 1 of Section 2 Sludge Reaeration Tank
4A12 Bay 2 of Section 1 Sludge Reaeration Tank
4A22 Bay 2 of Section 2 Sludge Reaeration Tank
4B Section 3 Sludge Reaeration Tank
5A1 Section 1 Contact Aeration Tank
5A2 Section 2 Contact Aeration Tank
5B Section 3 Contact Aeration Tank
6A1 Effluent Channel of Section 1 Contact Aeration
Tank
6A2 Effluent Channel of Section 2 Contact Aeration
Tank
6B Effluent Channel of Section 3 Contact Aeration
Tank
7A Effluent Channel of Settling Tanks of Sections
1 & 2
7B Effluent Channel of Section 3 Settling Tank
8 Waste Activated Sludge Distribution Box of
Pretreatment Tanks
74
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-
->
I
i
Figure 7. Photomicrograph of the Aeration Tank Mixed Liquors, Showing New Fingerlike
Growths of Zoogleal Bacteria
-------
C. Pretreatment by Plain Aeration and by Aeration and the Addition of
Haste Activated Sludge
1. General Conditions
This operational study task was begun on 19 May 1.970. Under this task,
the wastewaters that passed through treatment ystem A (previously
referred to as Sections No. 1 and No. 2 of the undivided Hagerstown
sewage treatment plant) were pretreated by aeration and the addition
of waste activated sludge while the wastewaters that passed through
treatment ystem B (previously referred to as Section No. 3 of the
undivided treatment plant) were pretreated by aeration alone.
Over the period of the study, the characteristics of the wastewaters
that entered the treatment plant remained essentially the same as they
were during the baseline study, particularly during May, June, and the
first week of July, although the raw wastewaters contained significant
amounts of dissolved oxygen, no sulfide and, surprisingly, quite fre-
quently no sulfite. On those rate occasions when sulfite was detected,
it was found at concentrations of only 1 mg/1 or less.
On 9 July 1970, an extremely heavy rainfall occurred in the Hagerstown
area, yielding 4.5 inches of rain from 1600 to 2300 hours. As a
result, incoming wastewater flows became abnormally high and remained
that way until 20 July 1970. Consequently, on 11 July 1970, the study
program of the project was suspended (wastewater sampling being dis-
continued) and was not started again until 20 July 1970. To make up
for the lost study time, the project effort was then extended to 24
July 1970 and therefore spanned a period of 68 days. Rain showers,
however, also occurred on 20, 21 and 22 July 1970 to add to area
flooding problems and to sustain high flows to the treatment plant
and to hamper the pretreatment studies.
These high "wet-weather" flows pointed up a major problem with the
city's sanitary sewerage system: Its tremendous susceptibility to
storm water runoff. From time to time throughout the life of the
project, high wet weather flows plagued the study program.
All through the first study period, the discharging of spent dye
stuffs into the sanitary sewerage by the textile dyeing plants in
the city continued as was readily evident by the regular week day
appearance at the treatment plant of intensely colored wastewaters.
Unfortunately, removal by the treatment plant of these colored wastes
was not noticeably improved by either of the two pretreatment methods
being employed.
Also during the study period, fluctuations in the pH of the raw
sewage occurred from time to time with unpredictable and low
frequency as they had during the baseline study. The fluctuations
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were generally no more than ± 1 pH unit and were "smoothed out" by
the time the wastewaters passed through the pretreatment tanks.
The pH's of most of the raw sewage samples composited daily during
the study fell in the narrow range of 7.1 to 7.35; yet, there were
daily composites with pH values as low as 6.5 and as high as 8.0.
The BODij of the composite raw sewage samples averaged about 200 mg/1
but varied greatly from day to day and, over the study period, ranged
from 83 to 403 mg/1. The COD's of the composites also varied con-
siderably, ranging from 296 to 1502 mg/1; their average value for the
period was 650 mg/1. The upper limit values of the BOD and COD
ranges were obtained on the same sample, which was considered a very
typical sample in that it contained an unusual amount of particulate
material.
2. Pretreatment by Aeration and the Addition of Haste Activated Sludge.
Treatment System A.
Although it had been planned originally to supply air at a constant
rate to the pretreatment tank of System A to maintain in the tank
fixed conditions with regards to both aeration and mixing and to
vary just the rate at which activated sludge was introduced into
the tank, the air supply rate was in fact actually changed over the
period within the limits of 2.0 to 2.5 thousand cubic feet of air
per minute as a consequence of the variations in air supply rates
that were effected in System B. Over the study period, the rate at
which waste activated sludge was introduced into pretreatment tank A
was increased step wise from zero to levels of 9.0 x 10^, 1.5 x 105,
and 3.0 x 105 gallons of sludge per day. The concentration of sus-
pended solids in the introduced waste activated sludge generally ran
about one percent. The maximum sludge feed rate of 3.0 x 105 gph
employed during the last weeks of the study created, however, a demand
for waste activated sludge that slightly exceeded the capability of
the system to generate the waste material. As a consequence of this
and the abnormally high stormwater flows that entered the plant
during July, the level of suspended solids in the mixed liquors of
System A gradually decreased during the final weeks of the study to
about 0.5%.
Although preaeration in pretreatment tank A had been effected ever
since the start of facility stabilization task, it was not until just
before the start of this study, the first of the operational study
tasks, that the modifications that were being made in the treatment
System A (construction of a new final clarifier and piping changes
in the existing final clarifiers) were completed; therefore, pre-
aeration was continued and waste activated sludge was not added to
the raw wastewaters entering pretreatment tank A until the third
week of the study to allow time to gather some good baseline data
on System A. Although it had been hoped that this data would show
that System A operated with comparable efficiency to System B,
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*<-** \*& -4-
1JI *'*
«.
**r-
*%
^^" -i; .
Yt4 ?^
Jsa -• ' >
&
•„
i .. a
*. -ir'
Figure 8. Photomicrographs of the Aeration Tank Mixed Liquors, Taken
during the Study of Pretreatment by Addition of Sodium
Nitrate and Showing Unidentified Filamentous Bacteria
among Small Zoogleal Masses with much Adsorbed Inert Solids
and the General "Burnt-Out" Appearance of Overage Sludge
Resulting from Excessive Recycling of Biological Solids
in the Treatment Plant
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significant operation differences between the two systems were found
to exist; and these, disappointingly, made the application of the
baseline data earlier accrued on the secondary units of System B to
the secondary units of System A, unrealistic. One of the major
differences noted was that in order to maintain a mixed liquor
suspended solids in the contact aeration tanks of System A at the
desired level of 2500 mg/1, the sludge reaeration tanks of system a
had to carry suspended solids at a level of about 10,000 mg/1; whereas,
in System B, the mixed liquor suspended solids in the sludge re-
aeration tanks needed to be carried at about only 6000 mg/1 to
achieve the same desired contact aeration tank mixed liquor suspended
solids level. This difference was due to the difference in the
influent wastewater flow to return sludge pumping rate rates of the
two systems. Moreover, it was evident that the air diffusion system
of System A (fixed air headers) could not drive as much air into the
mixed liquors of System A on a per volume basis as the air diffusion
system of System B could drive into the mixed liquors of System B.
As a consequence of these two differences, treatment System A did not
function as well as treatment System B under similar conditions.
While pretreatment by aeration alone was being carried out in both
systems, hydrosulfuric acid, H2S, was found frequently in the sludge
reaeration tanks of System A but found only very rarely in the sludge
reaeration tanks of System B. And, frequently during this study, the
HŁS concentrations were observed to build up in the sludge reaeration
tanks (to levels over 5 mg/1) then spill over and load the contact
aeration tanks of System A. Of course, during the baseline study,
when preaeration was not practiced, H2S appeared quite regularly
and in great abundance throughout the entire plant, being found in
the wastewaters of the primary settling tanks, the sludge reaeration
and contact aeration tanks, and final settling tanks. In this pre-
treatment study, this chemical species appeared with any regularity
in only the sludge reaeration tanks of System A.
In order to avoid sweeping the malodorous H?S gas from the sludge
reaeration tanks into the atmosphere in such quantities as to annoy
the public, chlorination of System A return sludges was practiced
intermittently, over the lifetime of the study task, at critical times
(normally from early evening to early morning, 1600 to 0200 hours) but
not at times, it is believed, that would affect test results. Of
course, this odor control practice did not permit the research team to
discover just how great the hydrosulfuric-acid-hydrogen-sulfide-gas
build up could become and, consequently, could heighten treatment
difficulties under each new operational condition tried. However,
scientific curiousity withstanding, consistent H2S production in a
system intended to function aerobically is, without question, in.
itself, symptomatic of unsatisfactory system performance no matter
how far it is allowed to proceed. So, it was felt that project
objectives were not subverted by limiting h^S production and that
the additional data that perhaps could have been gathered had
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chlorination of the return sludges not been practiced would not be of
sufficient value to the project to risk arousing public ire in trying
to get them.
Some of the data that was obtained in the study on pretreatment by
aeration and addition of waste activated sludge are presented in the
tables in the Appendices. The data shows that pretreatment by air
and waste activated sludge addition did improve the performance of
System A but show, in addition, that the resulting performance was,
generally, irregular and rather disappointing. Yet, there appears
in the data a trend of increasing improvement with increasing sludge
addition, the average percent dally BOD removal reaching 79% during
the period in which the sludge feed rate was at its maximum.
Unfortunately, however, the existence of this trend is somewhat
obscured by the uncertainty of what effects the high hydraulic
overloads experienced by the plant toward the end of the study
had on study results.
3. Pretreatment by Plain Aeration. Treatment System B
The air supply rate to the pretreatment tank of System B was varied
over the study period from 1.0 x 103 to 3.5 x 103 cubic feet of air
per minute. For a wastewater flow of 2.5 mgd (the assumed average
flow for the study), this variation amounted to a variation in air
application of 0.58 to 2.0 cubic feet of air per gallon of wastewater.
Initially, it had been planned that the air supply rate be increased
in steps every two weeks with the excess air generated by the constant
speed positive displacement blowers being bled off through the pressure
relief valves of the blowers themselves. However, for certain selected
air supply rates, it was found that the relief valves were not capable
of bleeding off the high surpluses of air generated. As a result, the
air supply rate was not constantly increased in regular steps over the
entire period of the study but was increased directly from the minimum
rate tried initially to the maximum rate tried and then decreased to
an intermediate rate which was achieveable only after a special air
release valve (gate valve) was installed in the air main.
Over the first two-week period of the study, pretreatment tanks B
received air at the 1.0 x 103 cfm rate and the daily BOD removals
by the system averaged 84%. For those study periods that followed
in which higher preaeration rates were employed, the averages of
the percent daily BOD removals were less than 84%. Specifically^
for those subsequent periods in which the air supply rates used
were 2.5 x 103 cfm and 3.5 x 103 cfm the average BOD removals were
only 79 and 78%, respectively. The dissolved oxygen concentration
in the pretreatment tank effluent increased with the stepped increases
in preaeration rate, going from an aeration step period average of
1.1 mg/1 for 1.0 x 103 cfm air to 5.6 mg/1 for 3.5 x 103 cfm air.
However, the primary tank effluent dissolved oxygen level did not
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change markedly over the study in the changes in the preaeration
rate, the dissolved oxygen level in the primary effluent generally
staying below 1 mg/1. J
Because it Deemed inexplicable that better treatment would be
obtained with only 1.0 x 103 cfm of air being applied in pretreat-
ment and not with the greater air applications, preaeration with
1.0 x ID-* cfta air was tried again during the final weeks of the
study task. This time, the daily BOD removal percentages were
greater than before, their average being 93%. The high flows
created by the wet-weather conditions that prevailed during this
latter period clouded the analytical picture somewhat and it is
difficult to say for certain why this particular improvement was
observed.
Although System B showed significant improvement in effecting
treatment with pretreatment by aeration, the almost consistent
appearance of rather low dissolved oxygen levels in and ORP values
of the liquors of the sludge reaeration and contact aeration tanks
strongly indicated that these units were at best just barely able
to supply sufficient oxygen to meet the exerted oxygen demands.
Perhaps, one of the most encouraging signs of treatment improve-
ment in both Systems A and B, which had been noted ever since the
pretreatment facility was brought into service and preaeration
was begun, was the reduction in the amount of suspended matter in
the final plant effluent. During the baseline study, final effluent
suspended solids levels as determined on 24-hours composite samples
were generally above 100 mg/1 and sometimes approached 200 mg/1.
After the baseline study, when preaeration was practiced, effluent
suspended solids levels fell well below 100 mg/1— particularly in
System B.
These data as well as the data mentioned earlier and other pertinent
analytical results that were gotten during the study task are also
tabulated in the Appendices of this report.
4. Improvements in Plant Biota
In general, it was noteable that, as a result of both pretreatment
methods employed, there were improvements in the quality of the
wastewaters being introduced into the mixed liquor basin and in
the performance of the basins themselves. These improvements
appeared despite the heavy hydraulic overloads caused by the heavy
rains in the Hagerstown area. It was particularly striking that
the sulfur precipitating bacteria that had been present during the
baseline study were absent during this study from the various
aeration tank mixed liquors and from the water of the preaeration
tanks, and that new finger! ike growths of zoogleal bacteria were
common in the mixed liquors. (See Figure 7.).
these findings represented a distinct improvement over the conditions
prevailing in the treatment plant before pretvedtment tids applied.
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D. Pretreatment by Addition of Sodium Nitrate and'by-Addition of Ammonia
1. General Conditions
During the approximately eight-week period of this study, as a result
of little rainfall in the Hagerstown area, the treatment plant did
not experience the high hydraulic overloads that it had during the
latter part of the preceding study. Daily total flows recorded at
the plant varied from 4.1 to 6.8 million gallons. Thus, daily flows
stayed well under the 7.5 mgd design average hydraulic load capacity
of the plant. The average flow for the period was only 5.35 million
gallons daily.
Sulfite, which had been associated with the discharge into the city's
sewerage system of spent liquors from the dye-stripping operations of
the textile dyeing plants located in the city, was rarely detected in
the raw wastewaters although the consistent appearance at the treat-
ment plant of intensely colored waters affirmed that the dyeing plants
continued to operate and to discharge dyeing wastes throughout the
study. And, with the exception of only a few cases in which readings
of 0.1 and 0.2 mg ^S/l were obtained, hydrogen sulfide concentrations
in the raw wastewaters- were generally zero. In addition, the dis-
solved oxygen levels in these waters were found to be lower than they
had been throughout the preceding study assumably, as a consequence,
of reduced stormwater inflow and infiltration during this study.
Over the study period, the raw sewage dissolved oxygen concentrations
ranged from 0.3 to 1.6 mg 02/1 with an average for the period of
0.68 mg 02/1.
The pollutional strengths of the raw wastewaters as determined on
24-hour composite samples ranged from 63 to 528 mg BODs/l and 338
to 1886 mg COD/1 with the averages for the two sets of measurements
being 262 mg BOD5/1 and 1040 mg COD/1. The lowest BODs and COD
values and the highest BOD5 and COD values were obtained, as might
be expected, on the same samples.
A number of unusually high pollutional strength raw wastewater
samples were obtained at different intervals during the study but
their high pollutional strengths were the result of materials
introduced into the raw wastewaters by the treatment plant itself.
The filamentous sulfur bacteria that were discovered in the plant
during the baseline study and that subsequently disappeared from
the plant during the first pretreatment study remained absent from
from the plant during this study. However, early in this study, a
new and different type of filamentous microorganism appeared
throughout the plant. This organism was of the kind sometimes
noted in "overaerated" or underloaded extended aeration activated
sludge systems. Photomicrographs of the Hagerstown sewage treatment
plant mixed liquors containing these organisms are presented in
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Figure 8 on the next page. The bacterial filaments are sheathed
with a very sticky, watery stuff to which small zoogleal masses
readily adhere; and, thus, they form biological mats that settle
poorly and are easily buoyed by microscopic bubbles or adsorbed
oils. Consequently, these filamentous growths that developed in
the plant created a biological sludge that would not settle well
in either the aeration basins or, when wasted, in the anaerobic
digesters. As a result, waste activated sludge eventually would
be returned to the head of the treatment plant via the digesters
with the drawn-off digester "supernatant liquor," increasing the
pollutional strengths and the suspended solids levels of the raw
wastewater samples.
By 11 September 1970, this undesirable recycling of biological
solids caused such a buildup of suspended solids in plant and
generated such a heavy organic load on the plant that treatment
System A, which was having difficulty providing sufficient air to
its aeration basins even under "normal" loadings, began to produce
in its aeration basins and to release from there to the atmosphere
considerable amounts of hydrogen sulfide gas and the sludge in the
final clarifier of treatment System B began to bulk severely. The
odor problem became intolerable on 17 September 1970 and around-
the-clock chlorination of System A return sludges had to be executed
to abate the intense pungent odor of H^S that was being produced and
creating much public annoyance. On 21 September, the suspended solids
level in the daily composite raw sewage samples was over 1300 mg/1.
On 22 September 1970, in order to stop the constant cycling and
buildup of biological solids in the treatment plant, the uncovered
digester tank of the plant was placed into service to receive and
store the heavily suspended solids laden digester supernatant
liquors. Although it was hoped that, in the open tank, the sus-
pended matter could be made to settle out by chemical means, through
addition of ammonia gas to raise the pH of the held liquors to above
8.5, effective solids separation was never achieved. However, the
use of the tank to store the digester liquors temporarily broke the
sludge recycling cycle and relieved the plant of its self-generated
overload.
As a result, this difficulty with suspended solids recycling in the
plant did not become troublesome again until two to three weeks later;
and, at that time, it was compounded by the occurrence of rising sludge
(believed to be caused by denitrification) in the primary settling
tanks of System A. Furthermore, at the end of the study period, with
relatively high concentrations of digester solids again coming into
the plant proper, a gas was noticed evolving from the primary tanks
of both Systems A and B. A sample of this gas was collected and
analyzed in the laboratory by means of gas chromatography and found
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to be a mixture of methane (62.5%), nitrogen (37.0%), and oxygen
(0.5%). This information thus indicated that a sizeable amount
of methane-forming bacteria has been swept from the digesters and
deposited in the primary tanks. Fortunately, during the two-week
"change-over period" that followed the termination of the pretreat-
ment study the solids problem abated and the treatment system
gradually returned to its baseline conditions.
2. A Search for the Cause of the Appearance of the Filamentous
Organism
Because the filamentous bacteria that produced the poorly settling
sludges had been seen before by members of the project team in only
"overaerated" or underloaded extended aeration sewage treatment
plants, it was felt that (1) they may be saprophytes of the mixed
liquor zoogleal bacteria—that is, that they may utilize for substrate
the walls zoogleal masses and other generally refractory materials of
lysed zoogleal cells—and thus become populous in underloaded systems
or (2) they may be a direct consequence of nitrate additions to the
wastewaters (or the relatively high nitrate concentrations produced
in extended aeration treatment systems exceeding having long aeration
periods). A laboratory experiment involving aeration for several
days of an unfed sample of the Hagerstown treatment plant mixed liquors
containing the filamentous bacteria and no nitrate was carried out
under the direction of the project biologist in order to test the
first hypothesis, i.e., to see if the filamentous organism would
proliferate under truly extended aeration conditions. They did not,
and so it was concluded that they were indeed not saprophytes of the
zoogleal bacteria. No effort unfortunately was ever made by members
of the project team to rigorously test the second hypothesis although
it was hoped that such a test could have been made before the project
was terminated.
3. Pretreatment by Addition of Sodium Nitrate
Under this operation study of the project program, sodium nitrate
(Chilean nitrate, 16% nitrate nitrogen) was added to the raw waste-
waters that were directed through treatment System A of the divided
treatment plant. The initial rate of addition was 250 Ibs of sodium
nitrate per day, and this rate was subsequently doubled every two
weeks over the eight-week period of the study. Thus, sodium nitrate
feed rates of 250, 500, 1000, and 2000 Ibs/day were employed. For a
wastewater flow of 5 mgd--the flow that had been anticipated for the
treatment system—these feed rates would have yielded nitrate-nitrogen
concentrations in the wastewater flow of roughly 1, 2, 4 and 4 mg/1,
respectively. However, over the study period, System A flows ranged
from 1.9 to 4.1 mgd and averaged 2.9 mgd; therefore, nitrate-nitrogen
concentrations that were introduced into the wastewaters were on the
average 1.7 times greater than planned.
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The sodium nitrate was added to the wastewaters at the head end of
the pretreatment tank of System A and this tank was aerated with air
supply rates being maintained at about 1400 ± 300 cfm over the study
period to promote mixing as well as to keep parti oil ate matter in
suspension. The sodium nitrate was fed to the wastewaters in solu-
tion form by the dry chemical feed machine of the project facility
except when the feed rate was 2000 Ibs/day. This feed rate exceeded
the feed rate capacity of the feed machine; and, consequently, the
output of the feed machine had to be supplemented by manually adding
sodium nitrate to the wastewaters in order to achieve the desired
feed rate.
As expressed in terms of BOD5 removal, the degree of treatment
obtained in the treatment system did not increase consistently with
increasing nitrate feed rates, although the highest average percentage
BODs removal, which was 85%, for any two-week period of the study was
realized for that two-week period in which the sodium nitrate feed
rate was at its maximum, 2000 Ibs/day. Yet, because of the high
levels of suspended solids that were in the system at this time and
which added more to the COD than to the BOD values of the wastewaters,
the average percent BOD removal for the same period was only 51%,
which is far lower than the average percent COD removal for any
preceding two-week period. On the other hand, however, the daily
percent removals of suspended solids over the entire study period
were of course much higher than previously experienced with the
overall average for the period being 91%.
Within a week after the sodium nitrate feed rate was increased to
2000 Ibs/day, during a period when considerable quantities of
activated sludge were being wasted into the pretreatment tank of
System A in hopes of alleviating the previously mentioned problem
of high suspended solids levels in the treatment plant, sludge
began rising in the primary tanks of System A—but not in the primary
tanks of System B. Consequently, on 8 October 1970, the nitrate feed
rate was reduced for two days to 8 Ibs/day, and the formation in the
primary tanks of a sludge-scum blanket subsided. The. nitrate feed
rate was then increased to 2000 Ibs/day again, and again a thick
(6-inches deep) sludge-scum layer formed on the surface of the
wastewaters in the primary tanks of System A, evidently as a result
of denitrification.
Only during that time when sodium nitrate was being added to the
wastewaters at the maximum rate employed where appreciable nitrate-
nitrogen concentrations detected in the effluent from the pretreatment
tank. At the lower feed rates, nitrate-nitrogen concentrations in the
pretreatment tank effluent were generally below 0.2 mg/1. Since the
nitrate nitrogen that disappeared in the pretreatment tank did not re-
appear in the system as either ammonia, organic, or nitrite nitrogen
to any significant extent, it is believed that the reduction in
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nitrate concentrations in the system was a result of the biological
utilization of nitrate as a hydrogen acceptor ("chemical oxygen
source") rather than as a nitrogen source, with the concomitant
loss of nitrogen as ^
The more significant experimental data obtained in this pretreat-
ment method study can be found tabulated in the appendices of this
report.
4. Pretreatment by Addition of Ammonia
In this study, ammonia was added to the raw wastewaters that were
passed through treatment System B of the divided treatment plant,
with the point of ammonia introduction being at the head end of the
pretreatment tank of System B. Initially, anhydrous ammonia from
manifolded 150-lb cylinders was fed by means of the ammoniator of
the project facility in ageous solution form; however, after several
weeks of study time had elapsed, direct feeding of gaseous ammonia
into the wastewaters had to be resorted to because the hydraulic
ejector assembly of the ammoniator became so severely clogged by
heavy scaling that ammonia feed rates above 60 Ibs/day could not
be attained. Direct feed was accomplished by temporarily modifying
the ammoniator in a manner that enabled the machine to still regulate
and measure gas flows, while ammonia was being withdrawn under pressure
instead of under a partial vacuum.
The initial ammonia feed rate used was 30 Ibs of ammonia per day.
For the wastewater flow that had been anticipated for the treatment
system—VIZ., 3 mgd—this feed rate would have increased the ammonia-
nitrogen concentration in the wastewaters (which, incidentally ran
about 15 ± 5 mg NH3-N/1) by only slightly more than 1 mg/1. Ammonia
feed rates were doubled every two weeks at the same time the nitrate
feed rates were doubled in the concurrent pretreatment study; thus,
ammonia feed rates of 30, 60, 120 and 240 Ibs/day were utilized in
the study. To insure accuracy of gas flow measurements, the rotameter
of the ammoniator was checked frequently by directly weighing the
ammonia cylinders to determine their losses in weight in a given
period of time, usually 24 hours.
Air was also introduced into the pretreatment tank of System B, the
introduction of course being made through air diffusion system of the
tank. As in the case of pretreatment by nitrate addition, aeration
was carried out to keep particulate matter in suspension and to mix
the wastewaters with the ammonia feed. Air supply rates to the pre-
treatment tank were maintained at 2000 ± 500 cfm over the lifetime
of the study.
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Although it had been anticipated from the wastewater flow data that
was obtained during the preceding study task that System B wastewater
flows would be about 3 mgd during this study, wastewater flows in
System B were actually less than that value for the study, ranging
from 2.1 to 2.9 mgd with a study average of 2.4 mgd. Even though
these flows were less than anticipated, they all exceeded the
design average hydraulic load capacity of the secondary units of
System B of 2.0 mgd. Yet, the treatment system generally effected
fair to good treatment over the study period.
The average percent removals of BOD5 realized for each of the four
different ammonia feed rate periods were: 90% (30 Ibs NHo/day),
89% (60 Ibs NH3/day), 80% (120 Ibs NH3/day), and 95% (240 Ibs NH3/
day) while the percent COD removals for these same periods were:
89% (30 Ibs NH3/day), 88% (60 Ibs NH3/day), 78% (240 Ibs NH3/day).
Moreover, over the entire study, the daily percent suspended solids
removals were usually in the 90's to give an overall average removal
of 95% for the study period.
All these figures indicate improvement in treatment in System B over
the treatment that was realized during both the baseline and preceding
pretreatment studies. However, the effect of the'lower wastewater
flows and, particularly, the solids problem experienced in this study
on the removal percentages was indeed significant and even may have
obscured the full treatment benefits that^may be deriveable from
ammonia addition.
Additional data obtained in this study are listed in tables that may
be found at the end of this report.
E. Pretreatment by Addition of Potassium Permanganate and by Addition
of Chlorine
1. General Conditions
This study, like the immediately preceding treatability study, was
conducted over a period of about eight weeks. Specifically, the study
was initiated on October 30, 1970, and concluded on December 26, 1970.
Dry weather conditions prevailed for nearly the entire time and,
except for the final four days of the study period, influent flows
ranged from 4.6 to 8.2 mgd and averaged 6.4 mgd, which is below the
7.5 mgd average design flow for the plant. During the last four days
of the study, high rains swelled the waste flows from 9.8 to 19.7 mgd.
The BODc's of daily composite samples of the raw sewage ranged from a
low of 82 to a high of 372 mg/1 and averaged 186 mg/1 while the COD's
of these same samples varied from 307 to 1334 mg/1 and averaged 671 mg/1
These BOD and COD averages are less by about one third than the
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corresponding BOD and COD averages of the first operational study.
In addition, plant influent suspended solids concentrations, which
were also measured on the 24-hour composite samples of the raw
sewage, ran from 40 to 800 mg/1 and averaged only 350 mg/1. Thus,
the average values for BOD, COD and suspended solids concentrations
over the period apparently show that, as far as these parameters are
concerned, the quality of the raw sewage had returned essentially to
baseline characteristics during this study; yet, however, over the
first week of the study period, the concentration of suspended solids
in the raw sewage and, concomitantly, the COD of the raw sewage were
consistently higher than the respective averages for the study period
evidently as a' result of the system having not yet fully returned to
baseline conditions from the unusual solids problem created in the
preceding study.
As in all the preceding studies, the highly colored wastes from the
textile dyeing plants constantly entered the treatment plant on week
days throughout the study period. And, during the first 3 to 4 weeks
of the study period, the level of sulfite and raw sewage usually
stayed at around 1 mg/1 although it did drop to a low of 0 mg/1 and
rose to a high of 2 mg/1. But, over the remaining 4 to 5 weeks of
the study, even though wasted dyestuffs continued to enter the plant
as before, no sulfite was ever found in the raw sewage. Moreover,
throughout the entire 8-week study period, no suflide was ever detected
in the plant influent or in any part of the treatment system. In
addition, only on one day out of the entire eight weeks of the study
was there no dissolved oxygen found in the raw sewage; otherwise, raw
sewage dissolved oxygen concentrations fell in the range of 0.3 to
4.8 mg/1 with 1.7 mg/1 being the mean dissolved oxygen concentration
value of the raw sewage for the study period.
F. Pretreatment by Addition of Potassium Permanganate
By means of the dry chemical feed machine that had been employed in
the previous study for feeding sodium nitrate, potassium permanganate
was added to the wastewaters being channeled into pretreatment tank A.
The chemical was applied as an aqueous solution at rates of 20, 40, 80
and 160 Ibs/day with each rate being tried in the sequence given for a
two-week period. Except for the last four days of the study, daily
waste flows through treatment System A remained fairly constant,
staying within 4.5 ± 1.1 mgd. Based on the 4.5 mgd flow, potassium
permanganate doseage rates were then 0.53, 1.1, 2.1, and 4.2 mg/1,
respectively, for the four feed rates utilized. Pretreatment tank A
was aerated with about 2000 cfm of air to insure good mixing of the
chemical with the wastewater.
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Best treatment of the wastewater by treatment System A in terms of
the average percent COD removal for a particular two-week doseage
period was achieved during the first two-week period when the
permanganate feed rate was just 20 Ibs/day. The average percent
BOD removal for the system during the two-week period was 83%.
However, in terms of percent BOD5 removal, treatment during the
first two-week period by the system was erratic and no better than
the two subsequent two-week doseage periods with the average percent
BOD5 removals for all three periods being about 75%. The average
percent BOD removals for the second and third two-week doseage
periods (when feed rates were 40 and 60 Ibs/day, respectively)
were 65 and 66%, respectively. Treatment deteriorated significantly
in the system during the final two-week period, owing to the greatly
increased wastewater flows and resulting relatively high solids
carry over in the final effluent of the system. The averages of
the daily percent BODs and COD removals for the final period were
only 69% and 62%, respectively. For this same period, suspended
solids removals averaged only 54%. In fact, the average percent
suspended solids removals for the various doseage periods consistently
decreased from the first period to the last with the percent removals
for the first, second and third periods being, respectively, 86%, 82%
and 71%.
Although the highest average percentage COD removal for any two-week
period during the study occurred during the first two-week period when
permanganate was being added at a rate of 20 Ibs/day, it seems from
the experimental data that this improvement was more apparent than
real, resulting from mainly high influent COD's caused by a typically
high influent suspended solids levels rather than as a direct effect
of permanganate addition. 6005 removals, which would not be as
greatly effected by high suspended solids levels in the plant influent,
were not necessarily better for this two-week period than for any other
of the study nor, in fact, was the quality of the final effluent of
treatment System A. Therefore, it appears reasonable to conclude that
the potassium permanganate additions produced no measureable improve-
ment in the performance of the treatment system.
2. Pretreatment by Chiorination
While the wastewaters coursing through treatment System A were being
pretreated by addition of potassium permanganate, the wastewaters in
System B were being pretreated by chlorination. As with the sodium
nitrate additions, one chlorine doseage rate was tried for a single
two-week period, then doubled the next second week period and so on
over the four two-week periods of the eight-week study. Chlorine was
initially applied at 150 Ibs/day, then increased to 300, to 600 and
finally to 1200 Ibs/day. Wastewater flows in System B for the first
31 days of the study averaged 1.45 mgd and ranged between 1.0 and
1.8 mgd. For the final 25 days of the study—except for the very
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last 4 days when flows rose and varied between 3.2 and 5.0 mgd in
System B due to the contribution of the previously mentioned storm-
water runoff flows—wastewater flows increased suddenly, averaging
2.4 mgd and ranging from 2.2 to 2.7 mgd. In any event, by calculation,
the chlorine doseages for the various feed rates and the average flow
values were approximately 12, 24, 30 and 60 mg/1, respectively.
As in the parallel study of pretreatment by addition of potassium
permanganate, the best treatment obtained in terms of COD removal
by prechlorination of the raw sewage was realized during the first
two-week period of the study during which time the chlorine feed
rate was 150 Ibs/day; the average percent COD removal for the entire
two weeks was 90%. But, unlike the situation that developed in the
permanganate study, percent BOD5 removals achieved by System B for
the period were also high and consistently so, their average being
93% and their value range, 89% to 98%. Moreover, except for one day
when the percent suspended solids removal obtained was unusually low,
73%, the daily percent suspended solids removals too were high.
They averaged 97% exclusive of the 73% removal value and the average
of the suspended solids concentrations in daily composites of the
final effluent were just 4 mg/1.
Over the three succeeding two-week study periods, the individual
period averages of the daily percent removals of all three wastewater
parameters--BOD5, COD, and suspended solids—consistently decreased
from one two-week period to the next. This trend can be seen in the
table of percent removal values given below.
TABLE 10. AVERAGE PERCENT REMOVALS OF BOD5, COD AND SUSPENDED
SOLIDS ACHIEVED FOR THE FOUR TWO-WEEK PERIODS OF
THE STUDY OF PRETREATMENT BY CHLORINATION
Removals
Pretreatment Chlorine Feed Rate
Period (Ibs/day)
%BOD %COD %SS
1
2
3
4
150
300
600
1200
93
84
73
69
90
71
65
61
97
90
76
74
90
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Shortly after the chlorine feed rate was increased to 600 Ibs/day
to initiate the third two-week study period, chlorine residuals of
the order of 0.5 to 1.5 mg/1 were frequently detected in grab samples
of the effluent of the primary tank (i.e., influent of the contact
aeration tank) of System B. When the feed rate was subsequently
increased to 1200 Ibs/day, chlorine residuals in grab samples of the
primary effluent were regularly detected and ranged as high as 1.5 to
5.0 mg/1; furthermore, chlorine residuals were detected for the first
time, although in trace amounts, in the effluent from the aeration
basin. General experience has shown that, while even very high
doseages of chlorine applied directly to the liquors of aeration tanks
for rather short periods of time may exhibit no appreciable effect on
the performance of the tanks, the continuous maintenance over an ex-
tended period of time of even relatively low chlorine residuals in a
mixed liquor basin can adversely effect the performance of the basin.
Consequently, it is believed that the frequent to almost constant
appearance of chlorine residuals in the influent of the aeration tank
of System B during the last 4 weeks of the study contributed to the
decrease in the degree of treatment achieved by the system. During
the last 4 weeks of the study and particularly the last two, bleaching
of suspended matter in the wastewater flow was readily apparent and
the odor of chlorine readily detectable throughout the treatment system.
6. Pretreatment by the Select Method
As mentioned earlier, the final operational study task of the project
involved the application of the pretreatment process revealed by the
preceding studies to be the most effective in treating the wastewaters
to all the incoming raw sewage and required the recommendation and
utilization of the entire sewage treatment plant. Thus, upon the
completion of the final pair of pretreatment studies, data obtained
from all six studies was reviewed; and it was concluded that pre-
chlorination carried out at the rate of 150 Ibs of chlorine per day
per 2 mgd of flow had yielded the best treatment results and that this
doseage, the lowest tried, was probably more than sufficient since the
degree of treatment that was realized had actually dropped off with the
higher chlorine doseages employed. Moreover, one important question
remained to be answered: How significantly had the dry-weather flow
conditions that existed at the time prechlorination was investigated
at the 150 Ibs/day feed rate enhanced the goodness of treatment?
Consequently, prechlorination was selected at the pretreatment method
to be applied to the entire incoming raw sewage flow of the Hagerstown
treatment plant.
The high flows that occurred during that last week of the final pair of
pretreatment studies lasted through the month of December and into
January. Although the "change over", i.e., recombination of treatment
systems A and B, was effected quickly by simpled valve changes, pre-
chlorination of the entire plant influent was not begun until
January 18, 1971, in hopes the high incoming flows would subside.
Unfortunately, they did not; but, nonetheless the final study was
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begun on January 18th since the project program had already fallen
considerably behind schedule by that time.
Chlorine was applied to the waste flow at a selected rate of 300
Ibs/day for the entire duration of the study, which was 68 days.
Except for nine days in early February when flows ran between 5.9
and 7.4 mgd, all daily flows exceeded the design hydraulic loading
of the treatment plant. The average of the daily flows for the
68-day period was 9.0 mgd. Thus, the applied chlorine doseage
based on this average flow value amounted to only 4 mg/1.
The constantly high wastewater flows through the aeration and final
settling tanks of the treatment plant swept biological active solid
from these tanks and out of the treatment plant. Consequently, the
maintenance in the contact aeration tanks of reasonable biomass was
difficult; in fact, contact aeration tank mixed liquor suspended
solids levels dropped to 600 mg/1 and even lower on several occasions
during the study period. As a result, treatment suffered appreciably.
For fourteen days scattered throughout the study period, final effluent
suspended solids level exceeded influent suspended solid levels; and
the daily percent suspended solids removals for the remaining 54 days
of the study averaged only 57%. However, for these 54 days, the
average concentration of suspended solids in the final effluent was
55 mg/1, which, although high, was not as high the value obtained
during the baseline studies. The daily percent BOD5 and COD removals
were very poor, their averages for the period being 63% to 53%, re-
spectively, and they varied widely from one day to the next as can
be seen from the data presented in the appendices.
During the last week in January filamentous organisms appeared in
moderate numbers in the mixed liquor of only the aeration tanks of
old system B and they persisted for no longer than two to three
weeks. They were identified as being to the genus Sphaerotilus and
were definitely not the same filamentous organism that was prevalent
in the plant during the baseline studies nor during ammonia and
nitrate addition studies. In any event, they apparently diminished
the settleability of the biological floe since floe particles were
swept readily from the plant by the high wastewater flows. In
general, however, the biomasses in all the various aeration basins
of the treatment plant appeared to be highly stabilized, containing
many stalked ciliates of the Vovtiaella microstomas species and young
zoogleal masses of bacteria.
Needless to say, the results of the study were extremely disappointing,
but they served to emphasize the city's great need to minimize the
inflow of stormwaters into the sanitary sewerage system.
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H. Sludge Dewatering Experiments
As part of the final operational study task of the project program,
the ease with which digested sludges and undigested waste activated
sludges that were produced in the treatment plant during the testing
of the select pretreatment method could be dewatered was to be in-
vestigated. Thus, prior to the start of the final study task an
empty plant digester, Digester No. 4, was readied for service; and,
shortly after the study was begun, when it was felt that "steady-
state" conditions in the treatment had been established, the prepared
digester was placed into operation, receiving and digesting sludges
in accordance with usual plant practices. The digester was brought
relatively rapidly into operation by means of the conventional pro-
cedure for reactivating a "stuck digester" (2), although some delay
was experienced due to the Inability of the digester heating system
(which had fallen in a state of disrepair) to adequately maintain
proper digester temperature, 95 ± 3°F. The sludges introduced into
the digester were a combination of primary and waste activated sludges
withdrawn from the primary settling tanks of the treatment plant.
One of the sludge dewatering studies undertaken was of the ease with
which sludges from Digester No. 4 and undigested waste activated
sludges from the aeration basins of the treatment pTant could be
dewatered on a vacuum filter; and, a second study was of the ease
with which just Digester No. 4 sludges could be dewatered on sand
beds. The vacuum filter utilized in the first study was a Komline-
Sanderson 3' x V pilot "Coilfilter" with 10 square feet of filter
area made of stainless-steel coil springs.
The sludges dewatered on this vacuum filter were first conditioned
with chemicals; namely, ferric chloride, lime, and/or a commercial
polymer preparation known as Floculate #532, manufactured by the
DuBois Chemical Co. Conditioning varied from treatment with ferric
chloride (10% solution) and lime (10% solution) to treatment with a
mixture of polymer, ferric chloride and lime. Preliminary laboratory
tests on the sludges determined the chemical requirements which pro-
duced the best filter cake for the types of sludges to be filtered.
The results of the vacuum filtration experiments showed that the
digested waste activated sludges, on the whole, had a slightly lower
moisture content, 73 ± 8%, than the undigested or raw wastes activated
sludges tested, 76 ± 6%, when preconditioned with ferric chloride and
lime. Little improvement in moisture reduction was realized when a
polymer was included in the preconditioning process, 71 ± 4% for the
undigested sludges and 71 ± 5% for the digested sludges tested.
However, these moisture contents are within the range of typical
sludge filter cake—70% to 80% by weight. The water content in these
dewatered sludges lend them satisfactory for short distance hauling
to a landfill for final disposal.
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An important measure of the efficiency of the filtration process is
of course the filtrate quality. The clarity of the filtrate is an
indirect measure of the efficiency of solids recovery, since these
solids which are not recovered in the sludge cake are discharged to
the filtrate stream. In the experiments performed under this
investigation the percentage of solids remaining in the filtrate
ranged from 1 to 3% for digested sludges treated with FeCl^ and
lime to 2 to 21% for raw sludge treated with the same chemicals.
Addition of the polymer compound (Floculate 532) in pretreatment
of the sludges seems to have improved the filtrate quality of the
raw sludges seems to have improved the filtrate quality of the raw
sludge filtrates; however, the limited amount of data available for
this experiment casts doubt on the certainty of this conclusion.
Overall, the digested sludges exhibited slightly better qualities
of the two types of sludges tested by vacuum filtration, as is
generally true.
As mentioned, also tested under the sludge dewatering task was the
dewatering of digested sludges on a sand bed. Three separate beds
were set up; one containing a 4-inch deep layer of sludge; another,
an 8-inch deep layer of sludge; and yet another, a 10-inch deep
layer of sludge. The results of this investigation showed that
dewatering of the digested sludge to a moisture content comparable
to that for the same type of sludge dewatered on a vacuum filter
required 4 to 5 days for the 4-inch thick sludge layer, 7 to 8 days
for the 8-inch thick sludge layer, and about 10 days for the 10-inch
thick sludge layer.
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Table 11. THE DECREASE WITH TIME IN THE PERCENT MOISTURE
CONTENT OF DIGESTED SLUDGE PLACED ON SAND
DRYING BEDS IN VARIOUS LAYER THICKNESSES
Date
4/15/71
4/17/71
4/19/71
4/20/71
4/21/71
4/22/71
4/23/71
4/26/71
4/27/71
% Moisture Content
4"
78.2
77.4
70.3
67.6
—
—
—
—
—
for Various Thicknesses
8"
81.1
83.8
78.8
78.0
76.5
74.1
64.8
67.6
—
of Sludge Layers
10"
82.6
82.5
79.0
78.4
75.4
75.6
62.2
70.2
70.7
95
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SECTION VII
SUMMARY
A. General
Much effort, well beyond the scope of the original project plan was
expended to define as accurately as possible the causes and to
develop practical solutions to the problems faced by the City of
Hagerstown in the treatment of its combined domestic-industrial
wastewaters. The original analytical schedule of the project program
plan was expanded, additional survey tasks undertaken, and operational
studies extended to obtain more complete information and to insure the
achievement of project objectives.
As a result of the project, it was clearly shown that the municipal
treatment plant suffered from severe hydraulic overloading during
wet-weather conditions and organic overloading from periodic slug
discharges of cottage cheese whey from a local cheese manufacturing
plant. It was revealed too that the aeration system of the plant
could not supply sufficient air to the aeration tanks of treatment
System A, the older of the two sections of the treatment plant, to
meet exerted oxygen demands. It was demonstrated that the plant
was not being adversely affected by toxic materials or even inhibi-
tory substances in the wastewaters as had been hypothesized unless,
of course, the effects of any toxic materials were masked during the
project by the overwhelming impact on the plant of the hydraulic and
organic overloads and the inadequacy of the aeration system of treat-
ment System A. Moreover, it was learned that a filamentous sulfur
organism existed in great numbers among the biota of the plant prior
to the execution of the project pretreatment studies and created a
poorly settling activated sludge and that this organism could be
destroyed through aeration of the raw wastewaters and the settling
characteristics of the activated sludge of plant thereby improved.
In addition, it was shown that preaeration eliminated H2S formation
in the primary tanks, keeping the raw wastewaters "sweet," and
minimized it in the aeration basins under slug organic loading
conditions and that, under high flow conditions, pretreatment by
plain aeration, by aeration with addition of waste activated sludge,
and by chlorination was well as perhaps by ammonia addition improved
plant performance. Finally, the project indicated that pretreatment
by sodium nitrate addition may lead to the occurrence of appreciable
denitrification in the primary tanks, causing there a rising sludge
problem and to the appearance in the biomass of a witherto unidentified
filamentous bacterium that can markedly increase the bulkiness of the
biologically active sludge.
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In summary, the project, through the application of Us pretreatment
schemes, significantly improved the performance of the treatment plant
under dry-weather conditions by: (1) markedly reducing H2S production,
(2) allowing higher mixed liquor suspended solids levels to be carried
without the fear of frequent odor formation, (3) decreasing the bulki-
ness of the biological floe and consequently the concentration of
suspended solids in the final plant effluent, and (4) increasing
considerably BODs and COD removals. Furthermore, the project resulted
in the development of specific recommendations affecting the operation
of the treatment plant. These recommendations were: (1) stormwater
inflows into the city's sanitary sewerage system should be reduced
appreciably, (2) the performance of the air diffusion systems of the
aeration tanks of treatment System A of the sewage treatment plant
should be improved, (3) the performance of the anaerobic digesters
of the plant should be upgraded, (4) a sound treatment plant preventive
maintenance program should be established and implemented, and (5) the
batch discharge into the sanitary sewerage system of high pollutional
strength and otherwise noxious materials by industries should be pro-
hibited. A further project recommendation was that industries currently
practicing batch waste discharging should be strongly encouraged to
install waste flow equalization tanks.
B. Subsequent Work
Shortly after the final operational study of the research project was
concluded, the city undertook the carrying out of the above-mentioned
recommended actions. The aeration tanks of System A were dewatered
one at a time to discover why it was so difficult to drive air into
these tanks. It was discovered that almost half of the carborundum
air diffusers in the system had been removed, (probably at one time
or another because they had become clogged or broken) and the air
header plugged. The city, subsequently, replaced all the missing
as well as the remaining carborundum diffuser elements in both Systems
A and B with new "sock" type fine bubble diffuser elements and supple-
mented the air supply of System A with surplus air from the pretreatment
facility. In addition, the city requested Breakstone Foods to proceed
with its planned installation of a waste flow equalization tank at the
company's Hagerstown cheese plant, a request with which the industry
quickly complied. Moreover, the city continued and expanded further
the industrial waste survey begun under the project, requesting
improvements in the waste disposal practices of other industrial
plants, and undertook an ambitious program to abate stormwater inflow
and infiltration in its sewer lines, and continued the pretreatment
of the incoming wastewaters using aeration with waste activated sludge
addition.
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As a direct result of the changes made in the aeration systems of the
plant, the application of the pretreatment method of preaeration with
waste activated sludge addition, and the installation by Breakstone
Foods of a flow equalization tank, plant performance improved remark-
ably (3). For October and November 1971, the monthly averages of
daily percent BOD5 removals were 92% and 94%, respectively. However,
plant performance dropped off during the months of January and
February 1972, evidently as a result of the reoccurrence of high
wet-weather flows. But, the plant still achieved 87% and 88% BOD5
removals for these months, respectively. Thus, it is anticipated
that when stormwater flows in the sewerage system are substantially
reduced, the treatment plant should be able to achieve consistently
a fairly high degree of wastewater treatment.
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SECTION VIII
REFERENCES
1. Wrigley, I.E., "Hagerstown, Maryland, Water Pollution Control
Plant," Unpublished report presented to the Hagerstown City
Council, Hagerstown, Md. (January 1967).
2. "Anaerobic Sludge Digestion," Manual of Practice No. 16,
Water Pollution Control Federation, Washington, D.C. (1968).
3. Barnhart, E., Private communication, Hagerstown, Md.
(May 1972).
99
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-78-0^3a
3. RECIPIENT'S ACCESSIOI*NO.
». TITLE AND SUBTITLE.
Pretreatment of the Combined Industrial-Domestic
Wastewaters of Hagerstown, Maryland - Volume I
5. REPORT DATE
March 1978 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO,
David S. Kappe
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Scientific Research Division
Kappe Associates, Inc.
Hagerstown, Maryland 21740
10. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
11060 EJD
12. SPONSORING AGENCY. NAME AND ADDRESS
Robert S. Kerr Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
13. TYPE OF REPORT AND PERIOD COVERED
Final Draft
14. SPONSORING AGENCY CODE
EPA/600/15
15,SUPPI FMFMTARY NOTES
Appendices to Volume I can be found in Volume II (EPA-600/2-78-043b), and can be
obtained through NTIS.
1&.ABSTRACT
The sewage treatment plant of the city of Hagerstown, Maryland—a manufacturing city
with about 130 industrial firms, which are classified in more than 25 different
product categories—receives for treatment domestic sewage and a diversity of indus-
trial waste and process waters. Some of these industrial wastewaters exert high
immediate and ultimate oxygen demands that could not be satisfied by the treatment
plant or were otherwise detrimental to the biological treatment processes of the
treatment system. Therefore, certain methods of "pretreating" the city's combined
wastewaters to render these waters more amenable to treatment by the existing treat-
ment plant were tried and evaluated. The pretreatment methods tested were intended
to assist the plant in meeting the oxygen demands by providing initial oxidation.
The methods were: diffuse aeration with and without the addition of waste activated
sludge, chlorination, addition of sodium nitrate, and the addition of potassium
permanganate. Ammoniation was also tried in an effort to destroy some of the more
noxious industrial materials in the wastewaters. Both aeration and chlorination
proved to be effective methods of pretreatment, with the efficacy of aeration being
enhanced somewhat by the addition of waste activated sludges. Both methods increased
the BODc removal efficiency of the plant under dry-weather conditions from less than
70% to Better than 90%.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Sludge
*Sewage Treatment
Hagerstown, Maryland
Combined Industrial/
Municipal
*Joint Treatment*
*Pretreatment*
50 B
8. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
116
0. SECURITY.Cl/iSS
UnclassTfTed
(This page)
22. PRICE
EPA Form 2220-1 (9-73)
100
•U.S. GOVERNMENT PRINTING OFFICE . 1978 0-720-335/6075
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