EPA-670/2-75
iM97§
Environmental Protection Technology Series
BENCH-SCALE HIGH-RATE DISINFECTION
COMBINED SEWER OVERFLOWS
With Chlorine and Chlorine Dioxide
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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EPA-670/2-75-021
April 1975
BENCH-SCALE HIGH-RATE DISINFECTION OF
COMBINED SEWER OVERFLOWS
With Chlorine and Chlorine Dioxide
By
Peter E. Moffa
Edwin C. Tifft, Jr.
Steven L. Richardson
O'Brien & Gere Engineering, Inc.
Syracuse, New York 13210
and
James E. Smith
Syracuse University
Syracuse, New York 13210
Project No. S-802400 (11020 HFR)
Program Element No. 1BB034
Project Officer
Richard Field
Storm and Combined Sewer Section (Edison, N.J.)
Advanced Waste Treatment Research Laboratory
National Environmental Research Center
Cincinnati, Ohio 45268
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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REVIEW NOTICE
The National Environmental Research Center—Cincinnati has
reviewed this report and approved its publication. Approval
does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection
Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
11
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FOREWORD
Man and his environment must be protected from' the adverse
effects of pesticides, radiation, noise and other forms of
pollution, and the unwise management of solid waste.
Efforts to protect the environment require a focus that
recognizes the'interplay between the components of our
physical environment—air, water 'and land. The National
Environmental Research Centers provide this multidisciplinary
focus through programs engaged in:
• studies on the effects of environmental
contaminants on man and the biosphere, and
• a search for ways to prevent contamination and
to recycle valuable resources.
Combined sewer overflows are one of the most neglected
sources of microbial contamination of the nation's waters.
This report covers several methods of overflow treatment
that are applicable within the economic and geographic
constraints imposed by the occurrence of overflows within
urban areas.
Andrew W. Breidenbach, Kh.D.
Director
National Environmental
Research Center, Cincinnati
111
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ABSTRACT
A bench-scale study of high-rate disinfection of combined
sewer overflows with chlorine and chlorine dioxide was
performed to aid in the design and operation of full-scale
treatment facilities. Four logarithm reductions in three
indicator bacteria and several common viruses were obtained
with 25 mg/1 chlorine or 12 mg/1 chlorine dioxide and two
minutes contact time. Sequential addition of disinfectants
enhanced the process such that only eight mg/1 of chlorine
followed in 15 to 30 seconds by two mg/1 chlorine dioxide
was necessary to obtain similar reductions.
The removal of suspended solids by microscreening through a
23 micron aperture had little effect on disinfection effi-
ciency- Disinfection increased slightly with increased
temperature, and a study of the receiving waters indicated
no bacterial or viral aftergrowth. Adenosine triphosphate
(ATP) was found to be a possible alternative to the bacterial
indicators of disinfection efficiency and microbial contamin-
ation. Electron spin resonance (esr) was used as a primary
standard method for quantitative measurement of chlorine
dioxide residuals.
This report was submitted in partial fulfillment of an Office
of Research and Development, U.S. Environmental Protection
Agency demonstration grant EPA No. S-802400 (11020 HFR) by
the Division of Drainage and Sanitation, Department of Public
Works, County of Onondaga, under the partial sponsorship of
the Environmental Protection Agency.
IV
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CONTENTS
Page
Review Notice ii
Foreword iii
Abstract iv
List of Tables vi
List of Figures viii
Acknowledgements xi
Sections
I Conclusions 1
II Recommendations 6
III Introduction 8
IV Experimental Procedures
General Procedures 10
Methods for the Assessment of Disinfection 18
Study of the Variables Influencing
Disinfection 34
Impact Studies 40
V Results and Discussion
Single-stage Disinfection 44
Two-Stage Disinfection 78
ATP Correlations with Bacteria 91
Impact Studies 95
Description and Operation of
Demonstration Facilities 106
VI Summary 125
VII References 131
VIII List of Publications 139
IX Glossary 140
X Appendices 143
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LIST OF TABLES
No.
1 Comparison of Simulated and Actual CSO 11
2 Esr Signal Intensity from ClC>2 Standard Solutions 14
3 Stability of ClC>2 Stock Solution 16
4 Effect of DDT on Total Coliforms Using MF 21
5 Comparison of MF and MPN Results in SCSO 21
6 Viruses Considered for Disinfection Study 25
7 Recovery of Viruses from SCSO with Membrane
Filters 27
8 Filter Recovery Tests on Virus in Diluted Sewage 29
9 Effect of Cl2 on ATP Standards 32
10 Effect of C102 on ATP Standards 32
11 Effect of Thio on ATP Standards 33
12 Correlation of ATP and Bacteria in Untreated CSO 33
13 ATP and Bacterial Reductions Upon Disinfection 35
14 Effect of Screening on Bacterial Counts 38
15 Free C12 Concentration in SCSO 52
16 Effect of Screening on Actual CSO 54
17 Effect of Screening on Virus in SCSO 54
18 Survival of Viruses in SCSO Treated with C1O2 63
19 Single-stage Disinfection with C1O2 in SCSO
Treated to Remove Demand 69
20 Effect of Solids Removal on Disinfection with
Cl2 and C102 71
21 Effect of Temperature on Disinfection of Polio-1
with C102 74
VI
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List of Tables (Cont'd)
No. Page
22 Average Bacterial Reductions for Single-Stage
Disinfection 86
23 Average Bacterial Reductions for Two-Stage
Disinfection 86
24 ATP Correlation Coefficients 92
25 ATP Stability Experiment 94
26 Enzyme Stability Experiment 95
27 Aftergrowth of Virus Disinfected with Cl2 103
28 Aftergrowth of Virus Disinfected with C1O2 103
29 Breakpoint Chlorination in SCSO 104
30 Maltbie Street Operation Schedule 118
31 Maltbie Street Analytical Schedule 120
32 West Newell Street Operation Schedule 122
33 West Newell Street Analytical Schedule 123
VII
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LIST OF FIGURES
No. Page
1 Esr Spectrum of 8 mg/1 C1C>2 Solution at -196°C 15
2 Esr Spectrum of 8 mg/1 ClC>2 Solution at 20°C 15
3 Static Decomposition Investigations of C102
in SCSO 17
4 Dynamic Decomposition Investigations of ClC>2
in SCSO 17
5 Effect of Blending on Bacterial Counts 23
6 Membrane Filtration of Early Storm CSO 28
7 Membrane Filtration of Late Storm CSO 28
8 Single-stage Disinfection Outline 36
9 Two-Stage Disinfection Outline 36
10 Aftergrowth Studies For Maximum Flow Conditions 42
11 Single-stage Disinfection of TC with Cl2 46
12 Single-stage Disinfection of FS with Cl2 48
13 Effect of Sample-to-Sample Variations on
Disinfection of 0X174 with Cl2 50
14 Single-stage Disinfection of 0X174 with Cl2 50
15 Single-stage Disinfection of TC with C102 56
16 Single-stage Disinfection of FS with C102 58
17 Single-stage Disinfection of 0X174 with C1O2 61
18 Single-stage Disinfection of Polio-1 with C102 61
19 Single-stage Disinfection of Several Bacteria
and Viruses with C102 64
20 Single-stage Disinfection of f2 with C102 64
21 Single-stage Disinfection of Polio-1 with C1O2
in a No-Demand System 66
viii
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List of Figures (Cont'd)
No. Page
22 Standard Dose Curve for Disinfection of Polio-1
with C102 66
23 Effect of pH on Disinfection of 0X174 with C1C>2 67
24 Effect of C102 on Cell-Associated Polio-1 67
25 Effect of Temperature on Disinfection of Bacteria 72
26 Effect of Temperature on Disinfection of 0X174
in SCSO 75
27 Effect of Temperature on Disinfection of f2 in
a No-Demand System 75
28 Comparison of Disinfection of f2 with Cl2 and C1C>2 77
29 Two-Stage Disinfection of Bacteria and ATP with
C102 (I) 80
30 Two-Stage Disinfection of Bacteria and ATP with
C102 (II) 81
31 Addition of Multiple Doses of C102 to 0X174 82
32 Two-Stage Disinfection of Bacteria and ATP with
Cl2 and C102 (I) 84
33 Two-Stage Disinfection of Bacteria and ATP with
C12 and C102 (II) 85
34 Comparison of Single-stage and Two-Stage
Disinfection of 0X174 with C12 and C102 87
35 Repeatability of Disinfection of 0X174 with
Cl2 and C1C>2 88
36 Two-Stage Disinfection of 0X174 with Cl2 and C102 90
37 Aftergrowth of TC in Receiving Water 96
38 Aftergrowth of FS in Receiving Water 98
39 Key for Samples Collected in Viral Aftergrowth
Study 102
IX
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List of Figures (Cont'd)
No. Page
40 Maltbie Street Site Plan 108
41 West Newell Street Site Plan 109
42 Maltbie Street Process Orientation 110
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ACKNOWLEDGEMENTS
These studies were co-sponsored by the U.S. Environmental
Protection Agency and the County of Onondaga.
The supervision of this project was conducted by
Richard Field, Chief, Storm and Combined Sewer Section,
Advanced Waste Treatment Research Laboratory, U.S.
Environmental Protection Agency, Edison, New Jersey;
John M. Karanik, Project Officer, County of Onondaga and
Frank J. Drehwing, Vice-President, O'Brien & Gere
Engineers, Inc., Syracuse, New York. The studies were
performed in the laboratories of O'Brien & Gere and the
assistance of all personnel who performed countless
analyses is acknowledged. Particular thanks are expressed
to David R. Hill and Stuart J. Spiegel of O'Brien & Gere
for their help in the design of the experiments and
literature review, respectively. Also thanks to
James McVea of the Biological Research Laboratories of
Syracuse University for his aid in the virus studies.
Many valuable suggestions were made by Cornelius B.
Murphy, Jr., Advisor in Chemistry, O'Brien & Gere, and
Cecil W. Chambers, Special Advisor in Bacteriology, U.S.
Environmental Protection Agency, Advanced Waste Treatment
Research Laboratory, Cincinnati, Ohio.
XI
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SECTION 1
CONCLUSIONS
Any widespread application of these results should be
contingent upon verification of these concepts in the
full-scale demonstration of prototype treatment facilities.
The degrees of mixing that may occur in full-scale
facilities could not be simulated on a bench-scale. All
these results are based on complete mixing.
1. Total coliform (TC) bacteria in simulated combined sewer
overflows (SCSO) were reduced to the target levels of
1,000 colonies per 100 ml in two minutes by the
following disinfectant dosages:
a. 25 mg/1 chlorine (Cl2) (only 50% of all trials)
b. 12 mg/1 chlorine dioxide (C102)
These same conditions reduced fecal coliform (FC) and
fecal streptococci (FS) bacteria to 200 colonies per
100 ml in two minutes.
2. These same conditions also achieved five log reductions
in poliovirus-1 and 0X174 bacterial virus. Although
target levels of viruses are not specified as part of
federal or state water quality effluent criteria, five
log reductions in virus populations would reduce the
highest anticipated viral counts in actual overflows
essentially to zero.
3. High-rate treatment by microscreening, followed by
disinfection, is a feasible method of reducing
microbial contamination of combined sewer overflows (CSO)
to an acceptable level.
4. The enhanced disinfection by using two-stage (sequential)
addition of Cl2 followed by C102 in 15 to 30 seconds may
be due to the regeneration of CIO 2 through the interaction
of chlorite ion (C102~) and
5. There is no enhancement of disinfection beyond the
expected additive effects when sequential addition of
the same disinfectant is practiced.
6. On a weight basis, CIO 2 is approximately twice as
effective as Cl2 in reducing bacterial and viral
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populations to target levels.
7. In the disinfection of contaminated waters with Cl2/ the
initial rapid disinfection is accomplished by free Cl2 /
which is converted to the less potent combined Cl2
species in one to two minutes. C102 is converted to • the
less potent C1C>2~ in the same time period.
8. Microscreening had no measurable effect on high-rate
disinfection with.Cl2 and'Only a slight • .positive -ef feet
with C102« -~A possible explanation is that the increased
rate of reaction between disinfectant and demands that
resulted from the' shredding of particulates upon screen- '
ing offset the increased numbers of exposed bacteria to
yield no net increase in disinfection.
9. Microscreening alone ^decreased suspended solids, but, in
some cases increased BOD5 and" bacteria counts. These
latter effects can be attributed to the reduction in
protective effects and ( increased surface area - due * to • the
shredding of the solids .
10. An' advantage of microscreening is that by exposing previ-
ously protected material, the time necessary for natural
assimilation of oxygen-demanding substances will be
shortened.
11. Cl2 and C102 demands can be attributed to different sub-
stances in wastewaters.
12. Within the dosages required for acceptable disinfection,
Cl2 and C102 do not measurably change pH, TOC, BODs, COD,
TKN or
13. The temperature variations associated with the north-
eastern climate had only a slight positive effect; on dis-
infection of wastewaters with Cl2 and C1C>2.. This devia-
tion from the large, positive, temperature effects observed
in no-demand waters is most likely due to a wide variety
of competing chemical reactions that occur- in wastewaters.
14. The Cl2 dosages (^50 mg/1) - required to achieve breakpoint
chlorin-ation in SCSO were far in excess of those dosages
required for achieving target- levels of bacteria and
virus, butt the cost is competitive with -other methods of.
ammonia removal.
15. Microorganism aftergrowth was not observed to be a
significant factor in this study. > However, the results
may be more 'a- reflection < of the, difficulties in
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simulating the conditions for aftergrowth than after-
growth itself.
16. Significant decreases in adenosine triphosphate (ATP)
concentration that parallel bacterial reductions have
been observed during the disinfection process. The
results of ATP measurements point to the potential of
using this indicator parameter as an effective means
of measuring bacterial concentration after disinfection
or controlling disinfectant dosages.
17. The effects of screening and temperature upon disinfec-
tion were difficult to observe because they were of
similar magnitude as the variations in duplicate trials.
The following conclusions are procedural in nature and
therefore not limited by the bench-scale scope of these
studies and need not be verified on a full-scale:
18. Blending for several seconds prior to bacterial enumera-
tion increases the counts in waters that have consider-
able suspended matter. Other forms of solids maceration
are not acceptable.
19. The levels of pesticides and heavy metals normally found
in wastewaters do not interfere with the membrane filter
(MF) technique for bacterial enumeration.
20. The MF technique can be applied to disinfected CSO if
periodic correlations are made with the most probable
number (MPN) technique.
21. The order of resistance of bacteria to disinfection with
Cl2 and/or C1C>2 is FS>TC>FC.
22. Poliovirus-1 is more resistant to disinfection than
other pathogenic viruses studied. Thus poliovirus-1
would be a good indicator of viricidal efficiency.
23. FS and poliovirus-1 show a similar resistance to disin-
fection, a fact that indicates that FS may be a better
indicator of disinfection than the current choice, TC.
It still remains to be established that the presence of
FS in drinking waters is an indication of significant
fecal contamination.
24. The tendency for both bacteria and viruses to resist
disinfection may be related to the lipids (fats) in the
cell membrane or coating.
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25. The particulate fraction of CSO is responsible for some
of the disinfectant demand of free C12 and
26. The normal variations in CSO from one storm to another,
and the chemical and microbial changes of samples stored
for more than a few days necessitated the use of an SCSO
in order to evaluate the effects of the variables that
influence disinfection within the defined project period.
27. An SCSO that consists of a mixture of raw sewage
collected at the same time each day and distilled water
will minimize any effects due to variations in chemical
composition.
28. It is necessary to increase natural virus levels in CSO
by seeding with known populations in order to observe
the effects of disinfection of viruses.
29. The lack of correlation between ATP and TC in different
non-disinfected CSO is attributed to the wide variations
in microbial composition.
30. The technique of electron spin resonance (esr) offers a
primary standard method for the detection and
quantification of C102.
31. The DPD method is the preferred colorimetric technique
for the measurement of free Cl2, mono-, di- and tri-
chloramine, C102 and C1O2~.
32. A fifty percent decrease in the C102 concentration in
stock solutions occurs in two weeks if the solution is
refrigerated and kept dark. The same decrease is
observed in twenty-four hours at 20°C under fluorescent
light.
33. Viruses may be recovered from CSO by absorption on a
filter pad and subsequent elution.
34. In the dosages required for high-rate disinfection, Cl2,
C1O2 and thiosulfate did not significantly interfere
with the bioluminescent determination of ATP.
35. A standard solution of ATP showed only a slight decompo-
sition after four days if properly buffered and kept in
the dark.
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36. The luciferin-luciferase enzyme reagent showed
significant decomposition after twenty-four hours
unless frozen. It should be noted that this reagent
consists of purified material. If the reagent is
prepared under less than pure conditions, this
evaluation must be repeated.
37. The development of an instrument to monitor ATP in
unattended operation is a realistic venture primarily
contingent upon the stability and cost of the enzyme
reagent.
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SECTION II
RECOMMENDATIONS
It is recommended that:
1. The results of the operation of the full-scale demonstra-
tion units be correlated with the bench-scale results to
determine the validity of using these bench-scale
studies for certain design parameters.
2. The role of suspended solids in disinfection of combined
sewer overflows (CSO) be evaluated on a full-scale to
determine the effect of screening on the disinfection
process.
3. The comparison of the effects of disinfection between
the swirl concentrator and the various microscreens
receive particular attention in the operation of the
full-scale facilities in view of the conclusions about
microscreening previously mentioned.
4. The full-scale facilities be operated in different seasons
to evaluate the effects of temperature on disinfection.
5. Consideration be given to the development of a remote
adenosine triphosphate (ATP) monitor to control the
addition of disinfectants.
6. The effect of chlorite (C102~) on receiving waters be
investigated before the widespread use of chlorine
dioxide (C102) is implemented.
7. C102 be considered as a disinfectant pursuant to the
previous recommendation.
8. The effects of mixing on high-rate disinfection be
thoroughly investigated on a full-scale study.
9. Two-stage disinfection with chlorine (Cl2) and C102 be
investigated to determine the mechanism through and
conditions under which enhanced disinfection occurs.
10. Future virus studies be conducted to assess their role
in CSO and the validity of using bacterial species
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and/or ATP as a measure of viral contamination.
11. Microbial aftergrowth studies be conducted in a natural
environment following high-rate disinfection. The pro-
blems of simulating such a situation make the laboratory
evaluation of aftergrowth extremely difficult.
12. For bench-scale comparisons of the factors that affect
the disinfection of CSO, a simulated CSO (SCSO) be used.
13. The procedural difficulties in running bench-scale
studies such as these be recognized. The greatest
care must be taken to preserve the intended experimental
conditions and to maintain sample integrity.
14. Electron spin resonance (esr) be studied further in
establishing a primary standard method for the determina-
tion of C102 in wastewater.
15. Additional studies be performed to determine the validity
of the membrane filter (MF) technique for enumerating
bacteria in CSO.
16. Blending be adapted as a preliminary step in the
bacteriological examination of waters that contain
significant amounts of particulate matter. Because of
the differences in individual blenders, a study of
bacterial counts vs. blending time should be performed
to determine the optimum time for each model.
17. Further work be done to determine an acceptable viral
indicator organism. This should include comparative
studies with the traditional bacterial indicator
organisms as well as pathogenic viral species.
18. A standard procedure for the recovery of viruses from
sewage be established.
19. The relationship between ATP and total bacteria counts
be studied.
20. A standard method for the measurement of ATP in sewage
be adopted.
21. Breakpoint chlorination be considered as a possible
method of ammonia removal in CSO.
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SECTION III
INTRODUCTION
BACKGROUND
The County of Onondaga, New York, through its Department of
Public Works, Division of Drainage and Sanitation, in con-
junction with the U.S. Environmental Protection Agency, has
undertaken a number of studies to define the sources and
extent of pollution of Onondaga Lake. Studies completed thus
far include the following:
- County comprehensive sewerage study!
- A survey of the major industries in the county^
- A limnological study of Onondaga Lake to determine its
present condition and project the effects of future
programs on the lake3
- A continuous lake monitoring program to measure the
effects of changing conditions on the lake4
As a result of the above, the County has embarked upon a major
program to increase the hydraulic capacity of the existing
wastewater treatment facilities and upgrade the degree of
treatment from primary to tertiary. It is projected that
these improvements will result in significant reductions of
pollutants discharged to the lake.
OBJECTIVE
Although these new facilities will result in significant
improvements to the lake, the inadequate capacity of the
existing sewer interceptor system results in combined sewer
overflows (CSO) to the tributary creeks of the lake. The
microbial contamination of these overflows precludes the use
of the lake for any contact recreation. Therefore, various
methods of treating these overflows were evaluated in the
county comprehensive sewerage study . It was suggested that
the CSO be conveyed to a centralized treatment facility
adjacent to the existing Metropolitan Sewage Treatment plant.
The high construction costs of this solution led to the
investigation of point-source treatment of CSO. Demonstration
grant EPA No. S-802400 (formerly 11020 HFR), was awarded to
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Onondaga County to investigate several methods of suspended
solids removal and high-rate point-source disinfection at two
outfall sites on the CSO system. The solids removal step is
primarily for the purpose of optimizing disinfection. The
term high-rate disinfection is used in this study to indicate
contact times of two minutes or less, as opposed to more con-
ventional contact times of 15 minutes or greater.
In order to establish a basis of design and operation for
full-scale demonstration facilities, bench-scale studies
were conducted to determine effective ranges of disinfectants
to be demonstrated. The effects of temperature, screen mesh
size, disinfectant dose and type, sequential addition of one
or more disinfectants, and contact time on the disinfection
process were evaluated. The limitations of relying exclusively
on indicator bacteria as a measure of microbial contamination
were recognized in this study. Consequently, the degree of
disinfection was measured not only with indicator bacteria
but also with several viruses. The possibilities of using
adenosine triphosphate (ATP) as a measure of disinfection
and as an indicator of microbial population were also eval-
uated. Efforts were made to determine the feasibility of
developing an ATP remote monitor for the ultimate purpose of
controlling the addition of disinfecting agents.
The effects of the discharge of treated CSO were assessed by
a study of aftergrowth in the receiving waters. Breakpoint
chlorination was studied for the removal of ammonia (NH3N),
an important nutrient, and residual chloramines, which may
be harmful to aquatic organisms.
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SECTION IV
EXPERIMENTAL PROCEDURES
GENERAL PROCEDURES
In order to assess the effects of the variables that
influence disinfection, a series of standardized procedures
for the characterization of samples, source and analyses of
disinfectants, and measurement of degree of disinfection
were developed. Research of this type has been done in the
past, to a large extent in pure cultures of various bacteria
and viruses in buffered solutions. However, this study
required that the investigations be conducted on combined
sewer overflows to aid more effectively in the design of
prototype treatment facilities.
Simulated Combined Sewer Overflows
The number of experiments necessary to determine the effects
of all the variables extended over a period of several months.
In order to ensure valid comparisons from one experiment to
the next, samples that were as similar as possible in
chemical and microbial characteristics were necessary.
However, there were several reasons why this could not be
done. Storage of combined sewer overflows (CSO) for more
than two days resulted in chemical and microbial
deterioration of the sample. The intermittent and
unpredictable occurrence of CSO precluded the collection of
a fresh sample each week. Additionally, the storm-to-storm
variations in the chemical and bacterial composition of CSO
(Appendix A) were judged to be too great to enable valid test
comparisons to be made.
Therefore, a simulated combined sewer overflow (SCSO) sample
was made each week by mixing equal parts of the influent to
the Onondaga County Metropolitan Sewage Treatment Plant with
distilled water. The results in Table 1 show a comparison
of the composition of an average of three SCSO with data
randomly selected from a six-month characterization of three
CSO sites.
The use of SCSO as a substitute for CSO eliminates all the
previously described problems and seems justifiable based on
the above data. The composition of each SCSO was checked
and no significant variations were observed.
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Table 1. Comparison of Simulated and Actual CSO
Maltbie Rowland Newell
Overflow SCSO Street Avenue Street
PH 7.1 6.4 7.5 9.6
Five Day Bio-
chemical Oxygen
Demand (6005)-
mg/1 130 82 25 24
Total Suspended
Solids (TSS)-
mg/1 156 282 482 32
Volatile Sus-
pended Solids
(VSS)-mg/! 92 146 140 30
Total Coliforms
(TC)-IOO ml 11,400,000 3,640,000 33,200,000 6,000,000
Ammonia Nitrogen
(NH3N)-mg/l N 5.41 0.66 2.28 4.39
Total Inorganic
Phosphate (T-IP)-
mg/1 P 1.60 0.83 1.28 2.40
Source and Analysis of Chlorine
The disinfectants evaluated in this study were chlorine
and chlorine dioxide (C102). It was necessary to obtain the
materials in pure form and to determine their strength and
residual concentrations after disinfection using a standard
procedure.
A stock solution of Cl2 was obtained as a five percent solu-
tion of sodium hypochlorite, known commercially as Chlorox®.
The stock solution was found to lose less then ten percent
of its available Cl2 content over a period of three months
if stored in the dark and refrigerated. The strength of
different bottles varied less than five percent from 50,000
mg/1 as available Cl2•
The strength of the Cl2 stock solutions was determined by a
sodium thiosulfate (thio) titration of iodine liberated from
potassium iodide using a starch indicator to detect the end-
point^. This technique does not differentiate between Cl2
and other materials that will oxidize iodide such as chlorite
ion (C102~) or chlorine dioxide (C102). The DPD Ferrous
Colorimetric Method^ has not only the desired specificity
but can also detect free Cl2f mono-, di- and tri-chloramine.
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No other accepted colorimetric technique has the capability
of the DPD method. The cost of the equipment necessary to
perform the amperometric technique5, which has the same
capabilities as the DPD method, did not seem warranted.
Replicate measurements of the Cl2 stock solutions by the DPD
method indicated that this technique lacked the precision of
the thiosulfate method. Therefore, both tests were performed
on Cl2 stock solutions: the DPD test to determine the quality
and the thiosulfate test to measure the strength. In all
cases, the solutions were found to contain at least 99
percent Cl2«
Cl2 is consumed in three ways by SCSO, namely, by reaction
with ammonia (NI^N) to form chloramines, by oxidation reac-
tions with organic materials to form organic chlorides, and
by decomposition to chloride (Cl~) as catalyzed by normal
light conditions. These reactions generally cause the
complete disappearance of free Cl2 in less than five minutes
and combined Cl2 in less than three hours in SCSO. Therefore,,
in the bench-scale studies which required some Cl2 determina-
tions at 30-second intervals, the time-consuming titrimetric
methods were not possible. Under these conditions, the less
accurate orthotolidine method^ was used to obtain approximate
Cl2 concentrations. When time permitted, the free and
combined Cl2 levels during and after disinfection were mea-
sured with the DPD technique.
Source and Analysis of Chlorine Dioxide
Methods of Generation—
C102 cannot be obtained as a prepared compound, but must be
generated as the demand arises. Tests showed that when a
stock solution was kept refrigerated in a container wrapped
in metal foil, C1C>2 had a half-life of two weeks, undergoing
a disproportionation reaction to Cl~ and chlorate (C1C>3~) .
In the demonstration of full-scale facilities, C1C>2 will be
generated upon demand, with no storage time involved. It was
desired to generate C102 for bench-scale study in the same
manner as in the full-scale demonstration, but the technology6
was not available at the time of this study.
Therefore, C102 was generated in a manner suitable for pro-
duction of small (one or two liter) quantities . A one
percent solution of sodium chlorite (NaClC>2) was acidified
to liberate C102 gas that contained impurities such as Cl2-
The mixture was passed through a scrubber solution of
saturated NaCl02 and the resulting purified C102 was bubbled
through distilled water to produce a stock solution of
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approximately 1000 mg/1. The reaction was carried out with
considerable care in a hood because of the mildly explosive
properties of NaC102 and the toxic vapors of C1C>2. The stock
solution was stored as above and discarded after two weeks.
Upon use, the scrubber changes from light green to dark
brown, at which point it loses its effectiveness, and must
also be discarded.
Methods of Analysis—
Colorimetric—Although there is no universally accepted
method for quantitative measurement of C1C>2, if a pure
solution of C1C>2 could be obtained, the thiosulfate titration
mentioned previously would yield satisfactory results. An
extensive literature review' indicated that the DPD method
as modified by PalinS is specific for C1C>2 in the presence of
free and combined Cl2 and ClO^"- The concentration of C102
in the solution that is actually titrated must be less than -^
two mg/1. The strength of the ferrous ammonium sulfate
solution used for titration should be diluted by a factor of
ten so that a quantity of titrant sufficient to obtain good ,
precision is consumed.
The combination of thiosulfate and modified DPD techniques
enabled standardization of the C102 stock solution. The
solution was always tested immediately prior to use, and if
the strength dropped below 500 mg/1, or if impurities were
found, the solution was discarded.
Electron Spin Resonance—C1C>2 also dissipates rapidly in
SCSO but its reactions are not as easily defined as those of
Cl2- The lack of a rapid, specific test for C1C>2 in sewage
has prevented any detailed studies of the behavior of C102
during the disinfection process. The fact that C1C>2 has an
odd number of electrons (23), and therefore an unpaired
electron, led to the conclusion that it could be studied by
electron spin resonance (esr)9. The theory and instrumenta-
tion of esr, which is a recently developed, highly sophisti-
cated analytical technique, are beyond the scope of this
report and are adequately covered in the literature10'11.
The technique is free of any interferences, gives a
continuous instantaneous value and is non-destructive toward
the sample.
A brief summary of the theory is as follows: energy is
absorbed from an applied magnetic field at a frequency that
is unique to the compound being studied. As the esr
spectrometer scans through the different frequencies, a
peak or series of peaks that correspond to the compound or
13
-------
compounds in the sample can be observed on a recorder. The
frequency at which the peak is observed can be related to
the structure and environment of the molecule. The height
or area of the peak is directly proportional to the concen-
tration of the material. If standard solutions are used to
calibrate the instrument, quantitative determinations can be
made.
The esr spectra were obtained using a Varian E-9 instrument.
The general standards of operation include a microwave
frequency of 9292 GHz, a field of 3300G, a scanning range of
1000G and a modulation frequency of 100K. . All spectra are
presented in the customary derivative form.
Samples of C1O2 in water investigated at -196°C (the boiling
point of liquid nitrogen) revealed a single broad line (see
Figure 1) with full width between points of maximum slope
equal to 85G+5G with g equal to approximately 2.02. The
more concentrated solutions showed increasing line broadening,
most likely due to uneven distribution of C102 molecules
within the polycrystalline ice sample.
The esr spectrum of C102 in water at room temperature
revealed a partially resolved quartet having a hyperfine
splitting of 17G+1G and a full width between points of
maximum slope of approximately 12G (Figure 2). A moderately
strong signal was observed from a one mg/1 concentration
while a very intense signal was obtained from a 15 mg/1
concentration.
Having ascertained that C102 gives a measurable signal at
room temperature when present in mg/1 quantities, the esr
spectra of a series of standard solutions were determined.
This standardization procedure was required for each
individual instrument operation. The results in Table 2
show that quantitative measurement of C1C>2 in this manner is
feasible.
Table 2 . Esr Signal Intensity from CIO? Standard Solutions
Esr Intensity
C102 mg/1
0.0
1.0
3.0
(Arbitrary Units) •
0
24
58
The stability of C102 was checked by placing aliquots of the
same solution into identical quartz esr tubes stored in the
14
-------
MAGNETIC FIELD STRENGTH, gouss-
MAGNETIC FIELD STRENGTH, gouss-
Figure I. Esr spectrum of 8mg/l
CI02 solution at-!96°C
Figure 2. Esr spectrum of 8mg/l
CI02 solution at 20° C
-------
dark. One was stored at -196°C and analyzed at room tempera-
ture, while the other was left at room temperature throughout
the experiment. After the large initial drop that is most
likely due to traces of impurities remaining in the esr tubes
which are difficult to clean thoroughly, analysis at 1 hour,
5 hours, 1 day and 2 days indicated only a slight change in
signal intensity (see Table 3).
Table 3. Stability of C102 Stock Solution
Esr Intensity
Time (Hours) (Arbitrary Units) % Change
0
1
5
17
24
48
73
56
64
66
50
64
—
-23.3
-12.3
- 9.6
-31.6
-12.3
Background spectra of SCSO at -196°C and room temperature
revealed no significant interfering peaks. Several small
absorptions were infrequently observed at low concentrations
(0.5 mg/1). However, they can be attributed to divalent
manganese, an ion common to urban sewage having a large
industrial component.
The stability or reactivity of C1C>2 in SCSO was measured in
two experiments designated as the static and dynamic studies
as shown in Figures 3 and 4. The static experiment involved
the addition of a quantity of C102 to SCSO sufficient to
create a concentration of 8 mg/1. The strength of the C102
dosing solution was determined by the thiosulfate and DPD
methods. Samples were pipetted from the disinfected SCSO
into closely matched quartz esr tubes at 0, 15, 30, 45, 60,
90, 120, 180 and 300 seconds and immediately immersed in
liquid nitrogen at -196°C. These samples and a series of
freshly prepared C102 standards in the range 0-10 mg/1 were
analyzed by esr in the described manner. The resulting
quantitative C102 values were plotted against time to give
the decay curve shown in Figure 3. The results show that all
the C102 had reacted within five minutes, most likely yielding
C1O2~. The results were further supported by the DPD method
which showed the sum of C102~ and C102 to be constant in each
sample.
The time required to collect and freeze the samples was
sufficient to give a degree of uncertainty to the results
from samples taken in the first minute. The dynamic
16
-------
in
"c
3
3
k_
o
Lkl
CC
01
UJ
6O 120 150 240
TIME, seconds
70 —
60 —
30
Z 40
30
20
10
TRIAL I
TRIAL 2
\
\
\
300
50
IOO 150
TIME , seconds
20O
Figure 4. Dynamic decomposition
Figure 3. Static decomposition investigations investigations of ClOo in
of CI02 in SCSO SCSO
-------
experiment was designed to circumvent this difficulty by
mixing the C1C>2 and SCSO in an esr solution mixing cell as
the C1C>2 peak was being monitored. The spectrometer was
calibrated with C1C>2 standards in the usual manner and the
mixing cell inserted in the instrument. " The flow rates and
strengths of the C1C>2 solution and SCSO were adjusted to
give a concentration of eight mg/1 C102 in a cell. The
solutions were then allowed to flow for several seconds to
establish a dynamic equilibrium while the spectrometer was
tuned to the C102 absorption peak-. The effluent stopcock
on the cell was abruptly closed to initiate the experiment.
It was estimated that no more than five seconds elapsed from
the initial mixing of the solutions to the time of first
observation of the esr signal. The only concern is that
adequate mixing might not occur, in spite of the fact that
the cell is designed to minimize these effects.
The results of this experiment are*" shown in Figure 4 and
indicate that C102 has a half-life of 60-90 seconds. This
is in agreement with the decrease in bactericidal and
viricidal efficiency observed in other phases of this study.
"This application of esr should be of great value in
establishing a primary standard method for the determination
of C102 in wastewater. The sophistication of the technique
and the expense of the equipment prevent the widespread
application of esr for the average environmental chemist.
However, the method can be used to evaluate the colorimetric
techniques and the reactions and kinetics of C1C>2 in
wastewater.
METHODS FOR ASSESSMENT OF DISINFECTION
The parameters used to evaluate the disinfection capabilities
of Cl2 and C102 in SCSO were bacteria, viruses, adenosine
triphosphate (ATP) and various chemical parameters. The
traditional indicators of fecal contamination have been the
coliform bacteria, but there is some doubt as to their
ability to serve as an indicator of viruses!2. Therefore,
in this study, actual viruses as well as bacteria were
measured in order to establish the validity of using bacteria
in disinfection studies of CSO.
The shortcoming of direct bacteria or virus enumerations is
that the test procedures require incubation periods of 24
hours or longer. This delay can be a serious problem when
the question of human safety is at stake. ATP measurements
were made to determine the feasibility of using this
parameter, the measurement of which takes only a few minutes,
18
-------
as a more useful indicator of microbial contamination.
Bacteriology
Indicator Bacteria—
Because the direct measurement of pathogenic bacteria and
viruses is beyond the scope of most laboratories, certain
bacteria that are known to originate from the same sources
are used to indicate the possible presence of pathogens.
The coliform group, consisting of both fecal and non-fecal
bacteria, was first used as the indicator organism partially
because of the relative ease with which the MPN test5 could
detect its presence. Even today this group is used in many
water quality standards even though it lacks the specificity
of some more recently developed tests. For these reasons,
the total coliform (TC) group was used as the primary
indicator organism in this study.
Recent developments show that a part of the coliform group,
namely, fecal coliforms (FC), may be a better indicator of
fecal pollution than the total group13. Therefore, this
test was included in the studies whenever possible. However,
there have been reports that indicate that both fecal and
total coliforms are less resistant to disinfection than some
of the pathogenic viruses1^. Fecal streptococci (FS) have
been advocated as indicators of fecal pollution15 and
possibly may be more resistant to disinfection than either
the coliforms16 or many viruses. Therefore, FS determinations
were carried out whenever time permitted.
Method of Bacteriological Analysis—
The membrane filter (MF) technique5 offers a rapid means of
detecting all the above bacteria. There have been some
questions raised about the validity of the MF technique on
chlorinated wastes and on samples containing large amounts
of particulate matter. These issues are treated in the
following paragraphs.
Toxicity—Standard Methods, 13th ed., states very explicitly
on page 678 the limitations of the MF technique in the
sentence "Experience indicates that the membrane filter
technique is applicable to the examination of saline waters
but not chlorinated wastewaters". Although recent studies
indicate that with proper precautions the above statement
may not be true1?'1®, the specific objections to the MF
technique, as first outlined several years ago,1^ are
considered in detail. The primary objections to the use of
19
-------
the MF technique in the bacterial examination of chlorinated
wastewaters arise from the need to filter large amounts of
sample to collect sufficient colonies to obtain a confident
count.
The suspended solids (TSS) collected on the filter pad may be
sufficiently great to clog the pores thus preventing the'
required amount of sample from being filtered. Also, the
layer of TSS on the filter pad may provide a barrier to the
nutrients adsorbed in the pad and thereby hinder bacterial
growth. Finally, the TSS may absorb disinfectants, heavy
metals and other toxic materials so that when collected on
the filter pad, the TSS may have a bactericidal effect.
The question of toxicity was explored by examining the over-
flows for heavy metals and chlorinated hydrocarbons and
conducting some controlled tests. Several samples were
examined by atomic absorption spectroscopy for chromium,
cadmium, lead, nickel, zinc and silver but only trace amounts
of less than 0.1 mg/1 were found. Gas chromatography showed
that several chlorinated species similar to the common pesti-
cides were present in the overflows at levels which sometimes
reached 1 mg/1 (Appendix A).
The effect of chlorinated hydrocarbons on bacteria counts
using the MF method was investigated by adding 10 mg/1 of DDT
to an overflow sample for one hour and dosing the sample with
chlorine for contact times of 30, 60, 120, 180 and 300 seconds*
The results of this investigation are presented in Table 4.
A sample containing 10 mg/1 of DDT was compared to a sample
containing no DDT, with no significant difference in TC levels
observed using the MF technique. Since this could be the
result of high dilution factor, the test was repeated on a
disinfected sample in order to reduce the dilution factor and
increase any potential effects. Again, no significant
difference was observed upon the addition of DDT.
Following these tests, Cl2 was added to give a concentration
of 20 mg/1 in samples that had DDT levels of 0 mg/1 and
10 mg/1, respectively. Chlorine contact times were varied
but no significant differences in TC levels were found in
any case as. shown in Table 4.
In addition to the studies conducted on SCSO, a brief deter-
mination was performed on pure cultures of TC. Confirmed
colonies of TC were lifted from the plates and grown in
nutrient broth. Aliquots of the inoculated broth were placed
in buffered solutions, and the stuides were performed on
these solutions.
20
-------
Table 4. Effect of DDT on Total Coliforms Using MF
Sample
DDT Cl2 Contact Total Coliform
(mg/1) (mg/1) Time (sec.) (counts/100 ml)a
Overflow 10
0
10
0
10
0
10
0
10
0
10
0
10
0
Pure Culture 10
0
0
0
0
0
20
20
20
20
20
20
20
20
20
20
0
0
0
0
0
0
30
30
60
60
120
120
180
180
300
300
0
0
6,300,000
8,700,000
12,000,000
9,400,000
410,000
560,000
135,000
130,000
12,000
32,000
9,400
6,300
5,300
1,700
552
535
Eacn count is the average of three blended replicates
To further assess the validity of using the MF technique for
bacterial measurements of CSO, the bacterial counts of a
series of untreated and chlorinated SCSO were determined by
both the MF and MPN methods. The results in Table 5 indicate
very little difference in the two methods.
Table 5. Comparison of MF and MPN Results in SCSO
Sample Bacteria
MPN MF
C12 (counts/100 ml) (counts/100 ml)
SCSO(l)
SCSO(l)
SCSO(l)
SCSO(l)
SCSO(2)
SCSO(3)
SCSO(4)
SCSO(5)
SCSO(l)
SCSO (2)
SCSO (3)
SCSO(4)
SCSO (5)
TC
TC
TC
FS
TC
TC
TC
TC
TC
TC
TC
TC
TC
0
0
0
0
0
0
0
0
15 mg/1 for
one minute
n
n
25 mg/1 for
one minute
n
9,000,000
9,000,000
7,000,000
900,000
7,000,000
5,000,000
7,000,000
9,000,000
1,200
1,400
700
7
21
11,200,000
8,600,000
10,800,000
766,000
6,800,000
7,200,000
7,700,000
8,500,000
960
1,100
840
13
19
All samples were blended
21
-------
These investigations indicated that the objections to the MF
method voiced in Standard Methods, 13th ed., do not apply to
SCSO. Since the SCSO in this study was chosen to represent
the first flush or most heavily contaminated CSO, this
conclusion may be generalized to include CSO. However, in
CSO there is the possibility of a slug of toxic material or
TSS higher than the values considered in these studies.
Therefore, both MF and MPN methods will be used periodically
during the remainder of the studies, particularly in long-
term composite samples.
Blending—A second problem in the bacterial analysis of
untreated and disinfected wastewaters is the protection of
the bacteria by harboring within the interstices of solid
particles and grease. This results in bacterial counts
that may not reflect the actual number of bacteria in the
sample.
Sonication and blending were considered as methods for
exposing the protected bacteria prior to analysis of the
samples. A literature search of the methods of solids
maceration with the use of ultrasonic waves indicated that
under the influence of ultrasonic fields with frequencies
commonly used for maceration, cell rupture may occur.
Significant kills of various strains of FC were observed
when subjecting the bacteria to a sound field for a period
of twenty minutes20. Early studies showed that cell rupture
could occur within 0.0005 seconds under similar ultrasonic
fields2^. Therefore, sonication could cause bacterial kills
before enumeration and did not appear acceptable. It was
decided to conduct a preliminary laboratory study on the
effects of mechanical blending.
Samples containing both high (>1,000,000) and low(<100)
counts/100 ml as measured by the MF procedure were blended
for varying lengths of time to obtain an optimum blending
time. The low counts were obtained by disinfecting a sample
of SCSO with 15 mg/1 of Cl2 at a contact time of five
minutes. A conventional household blender, Hamilton Beach
Model 50, was run at maximum speed for zero, two, four, six,
eight, ten, twenty, thirty and sixty seconds. The results
plotted in Figure 5 indicate that six seconds was the
optimum blending time for this model. A similar study
should be made for any blender used for this purpose.
On the basis of the results from the MF and blending tests,
the MF technique was used to measure all bacteria unless
otherwise stated with a minimum requirement of three
dilutions per sample and all. samples were blended. When the
22
-------
IV)
U)
E lo'r-
•••I- ?"
;
/
o. e
Si P
DISINFECTED WITH l5mg/ICI2 ^ «
lor 5 minut«s O z
1«1 o
^8
\
v--*
BLENDING TIME. iecond»
DISINFECTED WITH 15 mg/l
for 5 irnnjlet
1 I/ I M 1
0 2 4 6 8 IO 30 *O
BLENDING TIME. s*condi
-
o e
u. o
_l O
8S
Sg «>•,
>
0 2 4 6 8 IO 30 *0
BLENDING TIME, seconds
-O-O- UNSCREENED
SCREENED
(23 MICRON)
Figure 5. Effect of blending on bacterial counts
-------
MPN technique was used, five tubes of each dilution of 10 ml,
1 ml and 0.1 ml of sample were carried through the confirma-
tory test. It is intended to use the MPN procedure periodi-
cally in the remaining phase of this study as a check on the
MF procedure.
Virology
Viruses to be Studied—
As mentioned previously, the presence or absence of indica-
tor bacteria does not absolutely confirm or deny the pres-
ence of viruses. It was, therefore, decided to study the
effects of disinfection on several viruses in order to
compile more information as to the validity of using indi-
cator bacteria. Viruses are normally present in sewage and,
therefore, in overflows in such low numbers that their
detection requires a large amount of sample. This should
not imply that virus levels are sufficiently low that sewage
may be considered safe. There is no minimum amount of
virus that may be considered safe and no one has ever deter-
mined viral standards. The ingestion of even one viral
particle is sufficient to be an infectious dose for some
viruses.
The effects of disinfection on viruses are best assessed by
determining the net reductions in population as measured in
logarithms. The viral counts in most sewage are such that
a five log reduction can be assumed to yield zero virus.
In order to observe these five log reductions, the SCSO is
seeded to give an approximate initial count of 10^ organ-
isms/ml. It is assumed that a reduction from 10$ to zero
organisms/ml can be accomplished under the same disinfectant
conditions as a reduction from 10^ to 10-^ organisms/ml.
This is based on the fact that the number of organisms is
negligible compared to the number of disinfectant molecules
generally observed under no-demand conditions with adequate
mixing. Therefore, this is an idealized case of Chick's Law
in that the rate of kill is only a function of disinfectant
concentration and time. The initial concentration of the
species to be disinfected has no effect. The assumption is
valid for viruses in polluted water because: a) the viruses
remove a negligible amount of active disinfectant even at
concentrations of 10^2 organisms/ml, b) the inactivation of
one virus particle is independent of the inactivation of a
second, c) the same proportion of the population is inacti-
vated regardless of the starting population, and d) the dis-
infectant demand is the same regardless of initial viral
population.
24
-------
The majority of the virus studies were performed on three
viruses, bacteriophage f2, bacteriophage 0X174 and polio-
virus-1. The former two viruses were chosen because of
their relative ease in preparation and assay, their lack of
effects on humans and previous work that indicated these
viruses were similar to pathogenic viruses in resistance to
disinfection22. Poliovirus-1 was chosen because it is a
typical infectious, pathogenic organism. For other aspects
of the study, several other viruses were used. The names,
strains, common abbreviations and associated diseases of
the viruses are listed in Table 6.
Table 6. Viruses Considered for Disinfection Study
Name
Bacteriophage
Bacteriophage
Poliovirus
Herpes Simplex
Virus
Strain
f2
0X174
Sabin
Type 1
L2
Abbreviation
f2
0X174
Polio-1
HSV-L2
Disease
Bacterial Virus
Bacterial Virus
Polio
Fever Blisters
Newcastle Disease
Virus
Vaccinia Virus
California
Sharp
Yellow Fever Virus 17D
Coxsackie Virus B-3
Echovirus 7
NDV Chicken Virus
vaccinia Smallpox
YFV Yellow Fever
Coxsackie B-3 Encephalitis
ECHO-7 Meningitis
Growth , Purification and Assay Procedures —
Bacteriophage f2 was grown on a RNase 1" mutant, Escherichia
coli (E.coli) A19 ^' with yields of approximately 1 X lO^2
plaque~~forming units (PFU)/ml. Optimum conditions for the
production and assay of f2 required two media containing
(per liter): (A) tryptone-salt medium — 10 g tryptone,
5 g NaCl; and (B) complete medium — 10 g tryptone, 10 g
NaCl, 5 g yeast extract, 1 g glucose. The A19 cells were
grown for 17 hours in tryptone-NaCl at 37°C with vigorous
aeration; 5 ml of this overnight culture was used to
inoculate 100 ml of complete medium. After 1 to 2 hours
aeration (optical density = 0.065), f2 phage were added at
a multiplicity of infection of 5 (approximately 1 X 109
PFU/ml final concentration) , and the culture was incubated
for an additional 3 to 4 hours. The cells were then lysed
by the addition of 50 ml of chloroform and 20 ml of 10~3
molar (M) EDTA, pH 7.0, and stored at 4°C overnight. The
lysate was centrifuged in sterile bottles to remove cell
debris, decanted into sterile containers and stored at 4°C.
25
-------
Consistent f2 plaque formation could be obtained conveniently
with A19 cells which had been stored at -65°C. The cells
were grown for 17 hours in tryptone-NaCl .and preserved by
the addition of 20 percent glycerol (wt/vol) and freezing at
-65°C in 5 ml aliquots. After thawing at 37°C, 0.25 ml A19
was added to 2.5 ml of 0.7 percent soft agar overlay
containing dilutions of f2. Assay plates and overlay
required the complete medium for plaques.
Bacteriophage 0X174 was grown in broth cultures of E.coli C
according to the method of Sinsheimer^S with a yield of
5 X IQlO PFU/ml. Purified virus was prepared by differential
centrifugation followed by isopycnic banding in CsCl
(P = 1.42). CsCl was removed from virus containing fractions
by dialysis against 0.01 M phosphate buffer, pH 7.0.
The polio-1 was passed two times in human HEp-2 cells to
yield titers of 107 PFU/ml. The virus was grown and stored
in Eagle's Minimum Essential Medium with Earl's balanced
salt solution, containing twice the prescribed amount of
glutamine, 100 units penicillin, 100 ug dihydrostreptomycin
and 50 ug nystatin per ml. Agar overlay for plaque assays
contained the same medium plus 5 percent calf serum and 0.7
percent ion agar #2 (Oxoid). The virus was purified by
differential centrifugation and by gradient density
centrifugation in 11 to 45 percent (wt/wt) continuous
sucrose gradients. The other viruses used in this study
were prepared in a similar manner to the above, but grown
in the appropriate tissue culture.
Recovery of Virus from SCSO by Membrane Filtration—
The method of R.N. Rao (unpublished data) was used success-
fully to recover viruses from SCSO (1:1; tapwater:sewage)
as well as actual CSO. These waters were clarified by (1)
centrifugation in 250 ml bottles at 3000 rpm for 30 minutes
on an IEC centrifuge, (2) filtration through a membrane
prefilter, or '(3) filtration through a 23 micron aperture
screen. The pH was adjusted to 3.0 with HC1 and 120 mg
MgCl2/100 ml was added. The water was filtered through a
0.45 micron filter. The filters were removed, cut into
pieces and placed in a beaker with 30 ml three percent beef
extract, pH 8.0. The sample was allowed to stand 30 minutes
at room temperature with stirring or 20-60 second sonication.
Eluted samples could be preserved several days by shaking
with a few drops of chloroform and transferring the super-
natant solution to sterile tubes. Storage at 4°C in beef
extract-MgCl2 rather than freezing prevented losses in virus
due to clumping and osmotic shock.
26
-------
Table 7 summarizes typical experiences with this technique
using three enteroviruses as test subjects. All three were
recovered with high efficiencies. Sonication and prefil-
tration commonly result in recoveries greater than 100
percent due to dissolution of virus aggregates. Prefil-
tration consistently improved recoveries on the membranes as
well as increasing the volume which one filter can handle.
Reproducibility of these relatively high PFU counts was
acceptable.
Table 7. Recovery of Viruses from SCSO with Membrane Filters
Treatment
Virus inoculum (1 ml)
Virus sonicated in beef
extract eluant
Virus concentrated on MF
without prefilter, soni-
cated, eluted with beef
extract
PFU/ml Recovered
Coxsackie B-3 Polio-1
7.6 X 103 1.2 X 104
8.1 X 103 0.7 X 104
7.2 X 103 0.7 X 104
Virus concentrated on MF
with prefilter, sonicated,
eluted with beef extract 2.4 X 104 1.1 X 104
Echo-7
U.U ^ J.W
1.58 X 10
6.4 X 103
5.6 X 103
Extraction of the prefilter with beef extract at pH 8.0 did
not recover much of the virus. However, alkaline extraction
at pH 11.0 for 10 minutes did increase the yield.
The limitation of this direct method of adsorption of virus
is that the MF eventually clogs with sediment. Recovery of
viruses showed that a 142 mm MF could effectively concentrate
virus in a gallon of water before clogging if properly pre-
treated. Table 8 shows isolations of virus from 30 ml raw
sewage diluted to 3 liters. Similarly 3.5 liters of this
same material provided good recoveries of polio-1 when the
sewage was artifically seeded.
The filtration characteristics of actual CSO showed that CSO
clogged MF as quickly as raw sewage regardless of when the
CSO was collected. Figures 6 and 7 compare the filtration
of CSO collected early and late in a storm. Water was
collected within the first half hour of overflow and 6 hours
later after intermittent hard showers and continuous over-
flow. Surprisingly, the later flow was appreciably harder to
filter than the early flow. Prefiltration improved the
capacity of filters with both kinds of water. The experiment
may have been affected by the fact that heavy rains had been
27
-------
2200 -
2000 -
PREFILTERED
WITHOUT PREFILTRATION
PREFILTEREO
WITHOUT PREFILTRATION
10
15 20 25 30 35 40
45 0 5 10
TIME, minutes
15 20 25 30
35
40 45
Figure 6. Membrane filtration of
early storm CSO
Figure 7. Membrane filtration of
late CSO
-------
Table 8. Filter Recovery Tests on Virus in Diluted Sewage
Material Total Volume (ml) PFU/ml Recovered
Inoculum
Sewage diluted 1:100 with
tap water
Sewage diluted 1:100 with
tap water and seeded with
the inoculum
3
3
3
3
3
1
,000
,500
,500
,500
,500
1.
7.
5.
7.
1.
27
3
7
1
1
X 10*
60
40
117
115
X 103
X 103a
X 103
X 104
-a No MgCl2 used in the eluant
experienced almost daily for the two weeks previous to the
sample collection and consequently few TSS could be expected
to have accumulated. Thus there was very little flushing of
the sewers by the early CSO; the later flow was more turbid
with clay or soil particles in suspension.
Other Procedures—
One ml portions of stock virus solutions were added to the
SCSO before any screening or other pretreatment. The entire
supply of SCSO was thoroughly shaken and allowed to stand for
one hour to insure adequate dispersion of the virus. The
lack of any information in the literature on the inactivation
of virus with C102 necessitated some preliminary work in no-
demand systems of virus in various buffered solutions.
Citrate-phosphate, phosphate and borate buffers (0.01 M) at
various pH from 3.5 to 9.0 were used to determine the effect
of pH on the antiviral activity of C1O2- Fifty ml samples
of buffer at each pH containing 0.4 mg/1 C102 were inoculated
with 0.1 ml of CsCl purified 0X174 to a final titer of
5 X 10^ PFU/ml. Samples were taken at regular intervals,
neutralized and controls were maintained in buffer.
In addition to free organisms, viruses may exist in sewage
while trapped within cells or bound to cells which have been
excreted from the intestinal tract. To tests the effectiveness
of C102 treatment on such viruses, the following experiment
was performed.
Monolayer cultures of HEp-2 cells were infected with polio-1
at a multiplicity of infection of 5 PFU/cell. The cells
which had rounded after 36 hours incubation at 37°C were
shaken off the glass, washed once by centrifugation, resus-
29
-------
pended in glucose potassium nutrient (GKN) buffer and counted
in a hemocytometer. Ten ml of 9.2 X 10 6 cells/ ml were
recovered. At the beginning of the experiment 0.1 ml of cell
suspension was pipetted into a tube containing 5 . 0 ml
tryptosephosphate broth (TPB) and 1 . 0 ml chloroform. Since
the chloroform lysed any cells present, titration of this
sample revealed the total amount of virus present in the cell
preparation. Another 0.1 ml of cell suspension was pipetted
into 5 ml of TPB (no chloroform) which was centrifuged in a
clinical desktop centrifuge. Titration of the supernatant
revealed the free virus that was in the cell preparation.
The remaining infected cells were then added to 500 ml SCSO.
The total virus in the water sample was determined by
pipetting 5 ml of the inoculated water in 5 ml of 2 percent
TPB and 1 ml chloroform. After passing the remaining
infected SCSO through the 23 micron screen, another sample
for total virus was taken. The remaining infected SCSO was
divided into three 100 ml samples which were treated with 4,
8 and 12 mg/1 C102, respectively.
Adenosine Triphosphate (ATP)
General —
The quantitative determination of ATP using the bioluminescent
firefly reaction potentially offers a rapid alternative to
the bacterial measurements as an indicator of microbial
content of a water sample^ , 27 , 28 _ ATP is universally
present in all known living cells^, and it has been shown
that non-living sources of ATP occur only under rare and
contrived conditions^. Furthermore, ATP released by dying
microorganisms is quickly acted on by other organisms, and
converted to dissimilar phosphate forms. Thus, ATP can be
considered a measure of the total amount of living matter
within a
The hypothesis tested in this study was that ATP measurement
yields similar information to the measurement of the
traditional bacterial indicators of microbial contamination,
such as total coliforms, with respect to disinfection effi-
ciency. It is generally accepted that the presence of
coliform bacteria is an indicator of contamination by human
or animal wastes, and subsequently the possible presence of
an infectious viral or bacterial species. There are two
questions to be considered:
1. Are the coliforms present in large enough quantities
with respect to the total number of microorganisms
to allow correlation between ATP and TC, or
30
-------
2. Might not ATP be a better indicator of microbial
contamination than coliforms?
It is beyond the scope of this study to test the above
questions with sufficient thoroughness to make any definitive
statements. At this time only the possibility of such
correlations can be shown.
Analytical Techniques —
The determination of ATP is accomplished by simulating the
conditions within the firefly and measuring the amount of
light emitted. The entire process can be simplified by the
injection of a sample into the reactants contained within an
instrument suitable for quantitative light detection such as
the Dupont Model 760 Luminescence Biometer used in these
experiments. All reagents and supplies were obtained from
Dupont with the exception of morpholinopropane sulfanilic
acid (MOPS) which was obtained from the Aldrich Chemical
Company .
The biometer was calibrated using ATP standards following the
detailed instructions in the operations manual-^. ATP was
extracted by filtering five ml of sample through 0.45 micron
membrane filters (Millipore Corp.) and adding one ml of a
mixture of 80% 1-butanol (Fisher Scientific) and 20% MOPS
buffer to the filter. The pad was then rinsed twice with
2.5 ml of MOPS buffer and the total filtrate (six ml) was
stored in ice. After twenty samples had been extracted in
this manner and stored in ice, the ATP assays were made. The
instrument was calibrated at the beginning and end of each
run to check stability. The entire process for twenty samples,
including reagent preparation, required about two hours.
Interference by Disinfectants —
In order for ATP to serve as a measure of disinfection, the
disinfecting agents, in this case Cl2 and C102 , must not
interfere with the firefly reactions. To study this possi-
bility, Cl2 and C102 were added to an ATP solution to give
concentrations ranging from 1 to 100 mg/1 . The ATP content
of each solution was measured after 60 and 300 seconds
contact time. The results presented in Tables 9 and 10
indicate a definite reaction between ATP and disinfectants,
particularly
At the doses used for normal or high-rate disinfection, there
would appear to be only a slight interference. In wastewater
this effect should be even less than shown in the tables,
31
-------
Table 9 . Effect of C±2 on ATP Standards
ATP (yg/ml X 10"1)
Contact Time
Cl2 Dose (mg/1)
0
5
10
15
25
50
100
0 seconds
1.71
1.71
1.71
1.71
1.71
1.71
1.71
60 seconds
1.36
0.980
0.517
0.104
0.0841
0.0249
0.0290
300 seconds
1.05
0.900
0.318
0.0632
0.0966
0.0155
0.0143
Table 10. Effect of C102 on ATP Standards
ATP (ucf/ml X 10 1)
Contact Time
CIO? Dose (mg/1)
0
5
10
15
25
50
100
0 seconds
1.01
1.01
1.01
1.01
1.01
1.01
1. 01
60 seconds
0. 863
0.887
0.995
0.950
0.940
0.711
0.653
300 seconds
1. 06
0.886
0.925
0.574
0.482
0.236
0.354
since the ATP would become exposed only to the residual Cl2
and C102- However, to completely answer any questions, it
is recommended that sufficient thio be added to the MOPS
buffer-1-butanol extraction mixture to eliminate up to
100 mg/1 of residual disinfectant. The easiest way to
accomplish this is to add 2500 mg/1 thio to the MOPS buffer
used in all stages of the analyses. To test the effects of
thio on ATP, various amounts of thio were added to an ATP
solution and the amount of ATP measured after 60 and 300
seconds. The results are shown in Table 11.
The effect of thio on ATP can be considered negligible, and
this procedure was routinely adapted for all future ATP
measurements in disinfected wastewaters.
Correlation with Bacteria--
The correlation of bacteria with ATP was done in two stages
first, on untreated samples of CSO to determine the
relationship between bacteria and ATP, and second on
32
-------
Table 11. Effect of Thio on ATP Standards
ATP (vig/ml X 10"1)
Thio Dose (mg/1)
0
500
1000
2500
5000
0 seconds
1.54
1.41
1.62
1.56
1.60
Contact Time
60 seconds
1.48
1.39
1.46
1.44
1.49
300 seconds
1.22
1.16
1.20
1.24
1.21
disinfected samples to determine if ATP varies in a way
similar to bacterial counts upon disinfection. The first
stage was accomplished during the preliminary characterization
phase in which over 1000 samples of untreated CSO were
collected at different times and locations. Whenever time
permitted, ATP, TC, FC and FS were measured in addition to
many chemical and physical parameters. The results of this
work appear in Appendix A. There was very little direct
correlation between ATP and either of the three bacteria as
shown in Table 12.
Table 12. Correlation of ATP and Bacteria in Untreated CSO
Bacteria Correlation Coefficients
TC 0.033
FC 0.035
FS 0.034
The correlation coefficients were derived from a least
squares fit of over 250 points assuming a linear relationship.
The lack of correlation can possibly be attributed to the
variations in sources of ATP other than the three measured
bacteria and to the difficulty in measuring high ATP values.
Future work in this direction should include correlation
with total bacteria counts and pathogenic organisms.
This lack of correlation should not be a discouraging factor
in the application of ATP measurement as an indicator of
microbial contamination. The primary concern is that ATP
can be used to differentiate between the high bacterial
counts encountered in untreated CSO and the low bacterial
counts required by effluent limitations. If the coliforms
represent only a small fraction of the bacteria in untreated
CSO, poor correlations with ATP are to be expected. However,
if the coliforms are more resistant to disinfection than other
33
-------
bacteria, the correlations between TC and ATP should increase
in disinfected samples. In fact, the more resistant the
bacteria, the higher the expected correlation with ATP in
disinfected samples. This implies that if ATP is used as
a measure of residual bacteria in disinfected samples, any
decisions about the water quality would be at least as safe
as those based on coliforms.
Correlations in Disinfected Samples--
The second stage of the demonstration involved the measure-
ment of ATP and bacteria during the disinfection process.
It was felt that the previously observed sample-to-sample
variations in bacterial species would not be a factor pro-
viding that all bacteria had a susceptibility to disinfection
similar to or less than those observed. Any decrease in
bacteria would then lead to a corresponding decrease in ATP,
which could then conceivably be used as a measure of disin-
fection.
Several preliminary trials were performed to determine if
these decreases could be observed. The results given in
Table 13 indicate that parallel decreases occur upon dis-
infection. At this point in time the bench-scale studies
had progressed to the two-stage disinfection studies to be
discussed later, and ATP was added to the parameters to be
measured in this phase of the study. The results of this
extensive work will be presented and discussed at length in
the next section.
Chemical Parameters
The side effects of disinfection were determined by studying
the changes in certain chemical parameters. pH, TOG, NHoN
and TKN should be most susceptible to change in the presence
of C12 and C102. pH was measured with a Beckman Zeromatic
pH meter that was standardized with pH 'buffers 7.0 and 10.0
(Harleco Chemical Company). TOG was measured with a Beckman
Model 915 Total Organic Carbon Analyzer, and TKN and NH3N
were measured with a Technicon Autoanalyzer II, using the
hypochlorite reaction, with and without digestion,
respectively. The results of the chemical studies are given
and discussed in the next section.
STUDY OF VARIABLES INFLUENCING DISINFECTION
Introduction
The main purpose of the bench-scale study was to determine
34
-------
Table 13 . ATP and Bacterial Reductions Upon Disinfection
Disin-
fectant
Cl2
C12
ci2
Cl2
C12
C12
C12
Cl2
C12
Cl2
C12
C12
cio2
C102
C102
C102
C1O2
C102
C102
C102
C102
C102
C102
C102
Dose
(mg/1)
0
5
10
15
25
100
0
5
10
15
25
100
0
5
10
15
25
100
0
5
10
15
25
100
Contact
Time
(seconds)
30
30
30
30
30
30
300
300
300
300
300
300
30
30
30
30
30
30
300
300
300
300
300
300
ATP
(ug/mlXlQ-1
632.
125.
75.
73.
6.
1.
632.
73.
22.
7.
3.
0.
512.
110.
74.
21.
4.
3.
512.
45.
27.
5.
1.
0.
0
0
80
10
0
4
00
90
910
4
2
67
93
8
6
58
76
625
TC
(Counts/
) 100 ml)
4,700,
4,900,
4,000,
250,
1,
4,700,
3,400,
44,
1,
33,000,
1,150,
300,
103,
6,
33,000,
760,
40,
34,
000
000
000
000
300
0
000
000
000
010
5
0
000
000
000
000
900
300
000
000
000
800
700
0
FS
(Counts/
100 ml)
328
326
154
13
328
59
9
322
39
21
8
322
17
5
,000
,000
,000
,300
260
0
,000
,000
,700
590
5
0
,000
,000
,800
,000
730
41
,000
,600
,300
576
36
0
the effects of contact time, disinfectant dose and type,
temperature, method of addition of disinfectant and mixing
on high-rate disinfection. Each of the above factors with
the exception of the latter was varied in a range that might
be found in routine field operations while the remainder were
held constant. A standard procedure was established for the
addition of disinfectants and collection of samples as shown
in Figures 8 and 9.
The SCSO was prepared as previously described and passed
through a fine mesh screen if necessary for a particular
trial, as further described. The SCSO was then split into
the requisite number of one liter portions which were kept
in 1500 ml beakers or jars, hence the name jar tests. In
all cases one jar was reserved for a control sample. The
desired disinfectants in the various dosages were added to
the jar and rapidly mixed for fifteen seconds. The jars
35
-------
RAW SEWAGE
OJ
RAW SEWAGE
DISTILLED WATER
SIMULATED OVERFLOW
23 MICRON SCREEN
OR
NO SCREEN
» V T V T V T DISINFECTANT
0 mg/I 4 ma/I emg/l I2mg/l I6mg/l 20ng/l 25mg/l DOSAGE
1 i L I 1 1 1
<*> ^ <* i | «t ]
1 T—}
>0n
I
SAM PL E S TAK EN AT
0,15,30,60,120,180,300 SECONDS
15 SECONDS
MIXING
' UTER
BEAKERS
1 1 1
T
5 gait
T
DISTILLED WATER
SIMULATED OVERFLOW
23 MICRON SCREEN
OR
NO SCREEN
fVtttTTY DISINFECTANT
4 rog/I 4 mg/l 8mg/[ 8mg/l 2mg/l 2mg/l 4mg/l 4 mg/l DOSAGE
e» Jo Jo tk <}=> JL
I CI2 1 OR I ••
15 OH 30
SECONDS MIXING
Zing/1
T T T T T » Y DISINFECTANT
I mg/l 2mg/l 4mg/l 2mg/I 4 mg/l 2mo/l 4mg/l DOSAGE
JLl |JL| J.I 11
I
I
L
CONTINUOUS
MIXING
SAMPLES TAKEN AT
O,J5,3O,6O,I20,[8O,3OO SECONDS
Rgure 9. Two-stage disinfection
Figure 8. Single-stage disinfection outline .outline
-------
were maintained at the desired temperature and samples were
withdrawn at specified intervals for chemical, viral,
bacterial and ATP measurements. These samples were collected
in sterile, 125 ml bacteria bottles to which 12.5 ml of
0.025 N sterile thio had been added to halt the action of the
disinfectant at the desired time. The resulting concentration
of thio in the sample is approximately 600 mg/1 which is
sufficient for the neutralization of the maximum dosages5.
The neutralization reaction is instantaneous upon mixing and
the excess thio does not interfere with any of the parameters
to be measured.
A volume correction was made on all values to compensate for
the addition of thio. However, in the case of disinfectants,
the volumes were sufficiently small (1-2 ml) that no cor-
rection was necessary.
A portion of the sample was taken from the bacteria bottle
and prepared for the virus determinations. For virus assay,
5 ml of each neutralized sample was pipetted into a screwcap
tube containing 5 ml of 2 percent tryptone broth and 1 ml
chloroform. The tubes were shaken, the phases were allowed
to separate, and the tryptone broth was pipetted aseptically
into a sterile screwcap tube. These samples were refrigerated
until virus titration could be performed. A portion was
taken for chemical analysis and the remainder used for
bacteria and ATP measurements.
Selection of Contact Times
The contact times for disinfection were selected after a
review of the overflow conditions that exist within the
Syracuse Interceptor System had been completed. Dye studies
were performed on actual overflows under various flow condi-
tions to determine the time between overflow regulator
diversion point and the discharge of overflows to the
receiving water body. Since the area available adjacent to
the various overflow points is limited, the size of contact
tanks for disinfection will be necessarily limited in size
thereby limiting total detention time. The following range
of contact times were chosen as being representative of
possible field conditions: 0, 30, 60, 120, 180 and 300
seconds.
Disinfectant Dosages
It was felt that given the short contact times in high-rate
disinfection, Cl2 dosages up to 25 mg/1 might be necessary
to achieve the desired levels of 1,000 TC/100 ml and
37
-------
200 FC/100 ml. The values chosen for C12 were 0, 4, 8, 12,
16, 20 and 25 mg/1. The same dosages of C1C>2 were chosen to
facilitate comparison of the two disinfectants. It is
recognized that other disinfectants including ultraviolet
light (UV), bromine (Br2) and ozone (O3) do exist, but the
scope of this project includes only Cl2 and C1O2.
Screen Mesh Size
Fine-mesh screening prior to disinfection may act in two
ways. First, a fraction of the particulate matter, and
microorganisms absorbed therein, will be removed on the
screen. Subsequently, disinfection may be enhanced by
decreasing disinfectant demand and reducing the size of
protective solids. The bacteria and TSS values obtained
by screening through 23, 74 and 149 micron aperture are
shown in Table 14.
Table 14. Effect of Screening on Bacterial Counts
Screen
Opening
Trial (microns)
1 unscreened
149
74
23
2 unscreened
149
74
23
TC
(counts/
100 ml)
2,770,000
3,750,000
2,920,000
2,720,000
5,600,000
6,100,000
5,200,000
4,000,000
FS
(counts/
100 ml)
53,000
67,000
62,000
69,000
___
Total Suspen-
ded Solids
(mg/1)
270
206
166
142
161
112
62
58
Although the removal of TSS is a desirable effect, the main
purpose in screening in this study is to aid in disinfection.
The role of screen size in disinfection is covered in detail
in the discussion section.
The actual screening process was carried out after the raw
sewage was diluted 1:1 with distilled water. The entire
batch of SCSO was screened under 20 inches vacuum prior to
any disinfection studies.
Temperature Effects
The climatic conditions in Onondaga County are such that the
influent temperature at the existing Metropolitan Treatment
Plant varies from 8°C to 21°C3. The CSO may be subject to
even larger extremes of temperature. Therefore, it was
38
-------
decided to study disinfection at three different temperatures,
2°, 22° and 30°C. Unscreened samples were brought to
constant temperature at 2°, 22° and 30°C before being
disinfected with C3-2 and C1C>2. Procedures for sampling and
analysis were identical to those used in the other jar
tests as described in this section.
The temperature of SCSO samples was lowered to 2°C by
refrigeration of one liter portions. The jars were
maintained at 2°C while performing the disinfection and
sampling by keeping the sample in ice. The tests run at
22°C were performed at room temperature and were monitored
for fluctuations. The remaining tests were performed by
keeping the sample in a water bath and maintaining the
temperature at 30°C.
Additional studies were performed using only C1O2 and virus.
For these studies one ml of poliovirus-1 was pipetted into
50 ml SCSO in duplicate, pre-warmed bottles. The bottles
were shaken and then one bottle was treated with 4 mg/1 C102•
Dilutions of samples from both bottles were made and titered.
Inactivation curves were obtained at 4°, 12°, 22° and 30°C.
Addition Techniques
The effects of sequential or two-stage addition of one or
both disinfectants were compared to single-stage disinfection.
The initial concept was to use Cl2 as the first disinfectant
to reduce the demand and then add C1C>2 which could act
primarily as a disinfectant, as indicated by previous studies
on multi-stage addition of disinfectants33. The two-stage
studies were expanded to investigate this phenomenon more
thoroughly.
A series of two-stage reactions using Cl2 in 4 and 8 mg/1
dosages and C1C>2 in 2 and 4 mg/1 dosages were designed and
performed as illustrated in Figure 9. A sample of simulated
overflow was screened (23 micron), divided into 1500 ml
portions, and an initial sample taken. The first disin-
fectant was added. After the appropriate interval, the
second disinfectant was added. Samples were withdrawn
into bottles containing an excess of sodium thiosulfate for
analysis of TC, FS and ATP. The parameters TOG, NH3N, NC>2N,
N03N, TKN, pH and temperature were measured for a few trials,
but when none showed more than a 5% change from initial
values, they were dropped from further trials.
39
-------
Mixing
Mixing is recognized to have an important effect on the rate
of disinfection3^. However, it is difficult to simulate the
different methods of mixing that can be used during a full-
scale operation in a bench-scale study. Therefore, the
effects of mixing will be assessed in a later phase of this
project. In the jar tests, mixing was carried out very
rapidly (within 15 seconds) by a magnetic stirrer.
IMPACT STUDIES
Aftergrowth in Receiving Waters
The assessment of the effects of the discharge of treated CSO
into the receiving waters, in this case, Onondaga Lake and
several of its tributaries, is an important part of the
study. The discharge of residual disinfectants and their
by-products can have a toxic effect on plant and animal
life35. Although the disinfection process will reduce the
bacterial and viral population to an acceptable level, the
phenomenon of regrowth in the receiving water is well known3^.
In order to determine these effects in Onondaga Lake, a
series of tank tests were conducted. A sample of disin-
fected SCSO was added on a 1:1 ratio to Onondaga Creek water
taken immediately before the Syracuse city limits. This is
the ratio of total overflow volume, from an average storm
for the entire city, to minimum dry-weather creek flow. This
mixture was vigorously agitated for one hour which represents
one-half of the transit time in the creek for an average wet-
weather flow. Finally, the mixture was added to Onondaga
Lake water at a 1:14 ratio that simulates the ratio of the
above creek flow to the epilimnion of the southern end of the
lake. The calculations that support these estimated ratios
can be found in Appendix C. These conditions were chosen to
maximize the impact of the treated SCSO and therefore maximize
the safety margin.
The actual tests were performed on SCSO, screened (23 micron)
and unscreened, and disinfected with 25 mg/1 Cl2 and 12 mg/1
C102 for 30 and 60 seconds. Additionally, a non-disinfected
sample of SCSO was used for control purposes. The contact
times selected for design considerations indicated that these
would be the maximum times available in full-scale demonstra-
tion facilities. The dosages were selected to reduce the
bacterial counts to extremely low levels (<100) in order that
the difference between initial and final aftergrowth counts
could be more easily discerned.
40
-------
The chemical composition of the different samples of SCSO,
creek water and lake water was found to be essentially
constant throughout the tank tests. All work was conducted
at temperatures between 20°C and 25°C, the dissolved oxygen
in the tanks was kept at four mg/1 or greater and normal
room lighting conditions were maintained. These were chosen
to optimize aftergrowth. The disinfectant was added to the
SCSO and mixed for fifteen seconds.
Samples were then taken from the overflow before disinfection
and immediately before addition to the creek water according
to the outline in Figure 10. Prior to the addition to the
lake water, samples were taken from the overflow and creek
mixture, including the control, at 20-minute invervals. A
second control consisting of creek water was sampled and
added to lake water. These four mixtures plus a third control
of lake water were sampled at various times up to three days,
at which point the bacterial regrowth was assumed to have been
completed. The three indicator bacteria, TC, FC and FS,
several viruses and Cl2 and C1C>2 residuals were measured on
all samples.
Nitrogen Removal
The nitrogen and phosphate compounds in CSO represent a
significant percentage of the total contribution of nutrients
to Onondaga Lake-^. The complete reaction between Cl2 and
ammonia (NH3N), called breakpoint chlorination, is one way to
remove NH3N from wastewaters. Since a full-scale application
of breakpoint chlorination could be accomplished with approxi-
mately the same equipment as is used for disinfection with
chlorine, a bench-scale investigation was initiated to eval-
uate this possibility.
If the pH is maintained between 6.0 and 7.0, a theoretical
dose of 7.6 gm Cl2 per gm of NH3N results in the following
reaction37:
3 C12 + 2NH3 — N2+ + 6H + 6 Cl~
The products of this reaction change drastically if the pH
varies from the above range:
pH <6.0 3 C12 + NH3 »-NCl3 + 3H + 3 Cl"
pH >7.0 3 H20 + 4 C12 + NH3 ~N°3~ + 8 cl~ + 9H+
41
-------
BEAKER
JAR
t\J
DISCHARGE TO
TANK
OVERFLOW
\
SCREENING 8 /
DISINFECT ON /
<4 CONDITIONS)
0
CONTACT
TIME
0 seconds
CONTINUOU
30
SECONDS
CONTACT
TIME
30 seconds
CONTINUOU
60
SECONDS
CONTACT
TIME
ENTRY INTO CREEK
1:1
s
1:1
S
1:1 to
20,40,60mlnute
CONTINUOUS
20, 40, 60 minute
CONTINUOUS
LAKE EPIUMNION
KI4
9
1:14 _
t
1:14
0,l9mlnutes, 1,4,12 h
,2,3 doys
0,19 minutes, 1,4, 12
,2,3 doys
our*
hour*
60 seconds
CONTINUOUS
SAMPLINQ INTERVAL*
MIXING
SAMPLING INTERVALS
MIXING
20,40,60m,Bu... f.'iV,,,1""' *'*' " *"""* SAMPLING INTERVALS
CONTINUOUS
CREEK
WATER
CONTROL
n4 to
20,40,60mlnul»
CONTINUOUS
CONDITION
A
•
C
D
DISINFECTANT
CI2
CI2
CI02
ClOg
SCREENING.
0
23 MICRONS
0
23 MICRONS
MIXING
19 minutes, 1,4, 12 hours SAMPLING INTERVALS
1,2,3 days
MIXING
19minutes, 1,4,12 houn SAMPLING INTERVALS
I, 2, 3 doys
Figure IO. Aftergrowth studies for maximum flow conditions
-------
Both of these reactions are undesirable since nitrogen tri-
chloride (NC13) is an odorous, toxic material while nitrate
(NC>3N) is another nutrient. The natural buffering capacity
of CSO may maintain the pH in the desired range, but if not,
some form of pH control will be necessary. In tertiary
wastewaters the weight ratio required for breakpoint is
greater than the theoretical value of 7.6:1, rising to nine
or ten to one in secondary and primary effluents, respectively.
In screened CSO, the ratio is expected to be somewhere between
these latter two figures.
The average NH3N concentration ranged from 5 to 10 mg/1, so
Cl2 dosages were selected up to 100 mg/1. The experiment was
performed in a manner similar to the jar tests except for the
higher dosages. Samples were taken at 30 and 120 seconds for
each dose and analyzed for TKN, NH3N, (N03N + N02N) total
alkalinity (TALK) and residual C12. The thio used to termin-
ate chlorination interfered with the test for N02N, so that
separation of the NO3N + N02N measurement into its two compo-
nents was impossible. All the above tests were performed on
a Technicon AutoAnalyzer II using standard Technicon Method-
ologies38 except for residual C12. The DPD method was used
to analyze for free C12 and mono-, di-, and tri-chloramine8.
The pH was measured continuously and occasional samples were
examined for TC, FC and FS.
43
-------
SECTION V
RESULTS AND DISCUSSION
SINGLE-STAGE DISINFECTION
Chlorine
Presentation of Results—
Bacteriology—The results of disinfection with Cl2 using TC
and FS as a measure of efficiency are graphically presented
in Figures 11 and 12, respectively. The tabulated data from
which the graphs were drawn is contained in Appendix B. The
same four trials are presented in the same order in each
figure. The individual graphs in each figure represent a
separate trial for which a different SCSO was used. The
effects of contact time, Cl2 dosage, and screening can be
determined from these figures.
A detailed examination of Figure 11 shows that within the
two minutes specified for high-rate disinfection, a dosage of
16 mg/1 Cl2 achieved the required TC level (1,000 counts/ 100
ml) for only 25 percent of the trials. A dosage of 20 mg/1
showed no improvement in the results.
The results for FS showed a similar variability. A standard
of 200 FS/100 ml was chosen as a target level since the
characterization study showed that FS levels in CSO were
approximately 20 percent of the TC levels. This arbitrary
approach was taken since published standards for FS levels
could not be found. With the two-minute contact time, a
dosage of 25 mg/1 Cl2 or greater was necessary to reach the
target value.
The variations observed in duplicate trials is of the same
magnitude as the difference between screened and unscreened
trials. Based on this limited data, the direct effects of
screening as performed in this study are negligible.
These results are in rough agreement with the limited amount
of previous work on high-rate disinfection of CSO. In a
study at Grosse Point Woods, Michigan39, four log reductions
of TC and FS were obtained in CSO with dosages of 8.0 and
10.8 mg/1 C12, respectively, in 6.4 minutes. These compare
favorably with the observed three to four log reductions
44
-------
obtained in two and five minutes. The lower dosages were most
likely successful because of a lower Cl2 demand. Glover and
co-workers achieved three to four 4°f41 iog reductions with
1 mg/1 C124U in one study and 5 mg/1 Cl2 in another42 both in
a two-minute contact time. Again the lower dosages are attri-
buted to a lower Cl2 demand. Although no information on this
subject is given, the studies cited used actual CSO and not
necessarily a first flush. Therefore, this study, in which
the SCSO was chosen to represent a first flush, should require
higher dosages. Disinfection of treated CSO with Cl2 in
Milwaukee resulted in three to five log reductions in TC in
ten to twenty minutes43.
There is considerable literature on the other aspects of dis-
infection of bacteria with Cl2 but the above summarizes most
of the studies on high-rate disinfection of CSO. In order to
comprehend the nature of disinfection with Cl2 it is necessary
to consider other aspects. In buffered solutions of pure
cultures or in drinking water supplies, five log bacterial
reductions are observed in two minutes or less with no
decrease in free C12 residual44. In conventional sewage
treatment effluent disinfection, a common approach is to
maintain a total C12 residual of one to five mg/1 for a
contact time of fifteen minutes to several hours4^'4^. It
would not be practicable to list the numerous references to
disinfection with Gig/ but two recent review articles sum-
marize the field47' .
Virology--The inactivation of 0X174 was measured in order to
determine how much variation in kill would occur when different
batches of SCSO were used. Six replicate experiments were
performed over a period of five weeks with Cl2 as the disin-
fectant. Background counts of phage were determined in each
experiment and the background was always less than 0.005
percent of the 0X174 test particles. Figure 13 shows the
survivors obtained with 8 and 20 mg/1 Cl2- Approximately the
same degree of variation was observed at all sampling periods
for both concentrations. Despite the fact that a fresh
sewage sample was used to make the SCSO in each experiment,
the variation observed was well within acceptable limits.
Furthermore, the variations were random and did not seem
related to any particular sewage sample.
The antiviral activity of Cl2 at several concentrations is
demonstrated in Figure 14. The techniques used readily
distinguish a 4 mg/1 difference in C12 concentration. The
inactivation curves in this crude water are definitely bi-
phasic (two-stage). In the first phase (0 to 60 seconds), a
rapid inactivation of virus occurred which appeared to be
45
-------
SAMPLE INFORMATION.
BLCNTJCD
SCREENED 23m.cra
TEMPERATURE Z( O'C
»M 710
CH DEMAND 60O
[to9
j ro4
BLENOED
SCREENED 2 3 micro*
TEMPERATURE 220*C
pH 7.10
Clz DEMAND &00
120 I9O ISO ZIO
TIME, B«cofidt
TIME, seconds
Trial I
Trial 2
SCREENED
Figure II. Single-stage disinfection of TC with CI2
-------
SAMPLE INFORMATION-
•LENOED
UNSCREENED
TEMPERATURE 22CTC
pH T. 10
Cll DEMAND 600
E I0»
g
2
IAMPU INFORMATION'
BLENDED
UNSCREENED
TEMPERATURE 225"C
pH 720
Cl) DEMAND aOO
J I
0 ISO ISO 210
TIME, ittcondt
120 ISO 180
TIME, stcondt
Trial
Trial 2
UNSCREENED
Figure II. Continued
-------
SAMPLE INFORMATION'
00
10*
•LENDED
SCREENED 23iMcran
TEMPERATUfiE 21 O'C
pH 710
Cft DEMAND 6.OO
ISO 100
TIME , «*
120 ISO ISO 2IO
TIME, seconds
Trial
Trial 2
SCREENED
Figure 12. Single-stage disinfection of FS with CI2
-------
SAMPLE INFORMATION'
BLENDED
UNSCREENED
10* -
10s
VD
Z2O-C
T. IO
&OO
10'
I I I I I I I I
SAMPU {NFORMATION'
BI.ENOEO
UNSCREENED
TEMPERATURE 22.3'C
pH 7.20
Clt DEMAND ftOO
I I
3O 60 9O 120 ISO ISO 2IO 24O 27O 3OO
TIME, lecondi
0 SO M 90 I2O ISO IBO 2IO 240 ZTO .3OO
TIME, ••condl
Trial I
Trial 2
UNSCREENED
Figure 12. Continued
-------
X D*
Ul
O
120
T»
TIME.
Figure 13. Effect of sample-to-sample
variations on disinfection
of 0X174 with CI2
Figure 14. Single-stage disinfection
of 0X174 with CI2
-------
concentration-dependent as evidenced by the slopes of the
lines. In the second phase (60 to 300 seconds), disinfection
occurred at a definite, but lower rate. Regression co-effi-
cients for the slopes of the second phase of each line ranged
between 0.3 and 0.7, indicating only a very questionable
concentration dependence. This type of low grade second-
phase inactivation was also reported by Shuval49 in experi-
ments on Cl2 inactivation of polio-1 and ECHO-7 in which the
exposure time was extended to four hours. It is known that
when Cl2 is applied to water the primary disinfectant formed
is hypochlorous acid (HOC1), and that chlorine-demand sub-
stances (CDS) in wastewater compete with the microorganisms
for it46. Since the break in the biphasic curves is sharp
(especially at the higher Cl2 concentrations), it seems logical
to conclude that after that point no more HOC1 exists in the
water and that the remaining disinfectant action comes from
those combined Cl2 products which are commonly measured as
Cl2 residual in wastewaters50. Kelly and Sanderson5! indicated
that combined Cl2 is viricidal for polio-1 but at a much lower
rate than HOC1. Therefore, a longer disinfection time would
be required. Lathrop and Sproul5
-------
that the free Cl2 is rapidly converted to combined C±2 which
becomes the disinfecting agent and disinfection is relatively
much slower.
A brief study of the speed of the reaction between Cl2 and CDS
is presented in Table 15.
Table 15. Free Cl? Concentration in SCSQa
Initial Cl? Dosage (mg/1)
Contact Time (seconds)
0
30
60
90
120
180
300
5
5.
0.
0.
0.
0.
0.
0.
0
9
2
0
0
0
0
10
10.
1.
0.
0.
0.
0.
0.
15
0
8
7
1
0
0
0
Ib
4
1
0
0
0
0
.0
.3
.0
.5
.2
.1
.0
20
20.
8.
2.
0.
0.
0.
0.
0
7
4
8
5
2
0
25
2b.
9.
2.
0.
0.
0.
0.
0
4
3
9
5
4
1
as determined by DPD
Since the time of existence of the free Cl2 is the same as the
duration of the steep initial drops in Figures 11, 12 and 14,
the implication is that free Cl2 is the primary disinfecting
agent. The gradual decrease after the initial drop is assumed
to be due to the reduced disinfectant capability of combined
C12.
The exact mechanism through which free Cl2 attacks bacteria
and viruses is not known. However, based on the results of
this study, the following empirical observation can be made.
It is felt that disinfection is somehow related to the lipid
(fat) concentration in the cell envelope or membrane. FS
which has a low lipid concentration in the cell membrane5 ,
is more resistant to disinfection than TC, which has a higher
lipid concentration54. Also, polio-1, ECHO-7 and Coxsackie B-3,
which have no envelope and therefore relatively few lipids
exposed to Cl2, are several times more resistant to disin-
fection than the enveloped viruses such as HSV and YFV.
Therefore, the observation is that the greater the lipid
content in the outer layer of the cell, the greater the sus-
ceptibility to disinfection.
Effects of Screening—
As illustrated in Figures 11 and 12, there appeared to be
little or no predictable effects on disinfection with C12 by
the fine-mesh screening process. In fact, the variability in
duplicate trials was greater than any observed effect of
52
-------
screening. This somewhat surprising result parallels the
findings of Glover42. In order to understand the reasons for
this behavior, the effect of screening without disinfection
was investigated.
Screening without disinfection--The effects of screening alone
are summarized in Table 16. Although significant TSS removals
were accomplished with a 23 micron aperture, only slight
reductions in BOD5 and bacteria were observed. This is con-
sistent with Glover's work. The reasons for these phenomena
are as follows42:
1. Natural predators for bacteria are largely removed
by screening and are thus not present in large
numbers on the discharge side.
2. Large clumps of bacteria are broken up into numerous
smaller clumps or singlets by passage through the
screen.
3. The bacterial food supply is made more available
(more surface area is produced on the escaping
solids) by the screening process and growth kinetics
are enhanced. This is perhaps reflected in some of
the BOD5 measurements in which increases were ob-
served across the fine-mesh screen.
Although these statements are strictly hypothetical, these
results have been observed in both full- and bench-scale
studies. The need for future work on the mechanisms of
screening is apparent.
Screening followed by disinfection--It is somewhat surprising
that screening does not enhance disinfection in view of the
fact that primary settling, a method of TSS removal that is
inferior to screening, does enhance disinfection in domestic
sewage^b. A possible explanation of this observation is that
in high-rate screening many of the solid particles are removed,
but many are shredded and pass through the screen. Only a
relatively small fraction of the particles need to be shredded
to cause the total surface area to equal that before screening.
The vacuum filtration under 20 inches of Hg used to simulate
screening should have a similar shredding effect.
The rates of reaction of Cl2 with bacteria and CDS are both
quite rapid. Therefore, if the ratio of bacteria to CDS is the
same inside a particle as on the surface, screening will equally
enhance both reactions. The result will be no net observable
53
-------
Table 16. Effect of Screening on Actual CSO
en
Parameter
TSS
Unscreened
Screened
% Reduction
BOD5
Unscreened
Screened
% Reduction
TC (unblended)
Unscreened
Screened
% Reduction
FS (unblended)
Unscreened
Screened
% Reduction
1
161
64
60
100
90
10
6000000
2130000
64
312000
141000
55
2
139
62
55
150
153
-2
99000000
85000000
14
340000
486000
-43
3
64
14
78
22
15
32
207000
169000
18
29000
74000
-188
4
34
6
82
15
24
-60
2930000
1360000
54
36000
48000
-33
5
54
14
74
19
10
47
5000000
6300000
-26
196000
138000
30
6
270
142
47
120
117
2
17000000
12200000
22
478000
780000
-62
7
184
130
29
118
117
1
22000000
23500000
-7
497000
760000
-53
-------
increase in disinfection. Only a method of TSS removal that
does not shred the particles can be expected to enhance high-
rate disinfection. This is not to say that screening is not
a useful technique in wastewater treatment. Obviously, many
microorganisms and TSS are removed by screening. Even though
the impact of these removals is not felt in subsequent high-
rate disinfection, the long-lasting or downstream adverse
effects of screened effluents should be less than for un-
screened effluents. Any aftergrowth of bacteria in the
receiving waters should also be decreased by screening.
The effects of screening on virus removals could not be
determined because of the extremely low levels of natural
virus. As might be expected there was no appreciable effect
of screening on the seeded viral samples as shown in Table 17.
This was true even if the sample was stirred slowly for
twenty hours after seeding and before commencement of a test.
Therefore, it seemed reasonable to assume that free virus
particles will not be absorbed by particulate matter in such
a situation.
Table 17. Effect of Screening on Virus in SCSO
74 y
aperture
Time of
Treatment
0
24
hour
hour
Screening
Unscreened
Screened
Unscreened
Screened
PFU/ml
2.
2.
2.
2.
8 X10'
4X10
4X10
4X10
7
7
7
Percent
Recovery
100
85
100
100
2
3 y aperture
PFU/ml
2.
2.
2.
2.
2X10'
7X107
2X10?
3X107
Percent
Recovery
100
122
100
104
Disinfection tests also showed no difference in screened and
unscreened samples.
Chlorine Dioxide
Presentation of Results--
Bacteriology--Figures 15 and 16 present the results of single-
stage disinfection with C102 on screened and unscreened
samples. The tabulated data may be found in Appendix B.
Adequate high-rate disinfection with C102, as measured by TC,
was achieved with 8 mg/1 C102 50 percent of the time and with
16 mg/1 75 percent of the time. Satisfactory disinfection
for the remaining trial was not achieved even with 25 mg/1.
Whatever the level of disinfection, there was a rapid initial
55
-------
SAMPLE INFORMATION'
BLENDED
SCREENED 23 micron
TEMPERATURE 213'C
I ISO 180 210
TIME, seconds
24O 27D SCO
SAMPLE INFORMATION
BLEKOED
SCREENED 23m
TEMPERATURE 235 "C
pH 720
CIO? DEMAND «OO
120 ISO 180
TIME.ucandi
210 140 ETC 9OO
Trial I
SCREENED
Trial 2
Figure 15. Single-stage disinfection of TC with CIO2
-------
(Jl
O SO «O »0 I2O ISO 160 2IO 24O Z70 5OO
SAMPLE INFORMATION-
•LENDCO
UNSCREENED
TEMPERATURE 2U'C
p H 7.10
ClOi DEMAND 5.0O
O 5O 61
TIME, seconds
24O ZTO 3OO
Trial I
UNSCREENED
Trial 2
Figure 15. Continued
-------
SAMPLE INFORMATION.
BLENDED
SCREENED 21 rr,
TEWPEHHTUFIE 23 3* C
CO
I2O 130 ISO 21O 24Q 270 3OO
TIME, seconds
I BO Z>0 240 270
TIME.itconds
Trial I
Trial 2
SCREENED
Figure 16. Single-stage disinfection of FS with CIO2
-------
Ln
SAMPLE INFORMATION-
BLENDED
UNSCREENED
TEMPERATURE 21VC
P M T.2O
ClOi DEMAND 6.OO
3° «O 9O (20 130 iao 2IO 240 27O 300
10*
INFOAMAT1ON <
•LCNOEO
UNSCREENED
TtUWtRATUflE 21 3-C
»H 7.10
OOt 0£M&NO 3.00
0 30 «0 *0
IZO 190 mo 2(O 24O 270 3OO
TIME, stconds
Trial I
Trial 2
UNSCREENED
Figure 16. Continued
-------
dropoff that was complete at approximately 30 seconds, with
very little kill obtained after that point.
The results for FS showed a pattern similar to TC, with
8 mg/1 C102 sufficient to meet the arbitrary levels of 200
FS/100 ml 50 percent of the time. The initial rapid drop was
also observed. The implication is that C1C>2 itself is the
disinfecting species and that the decomposition product, C1C>2~
has little disinfectant ability. The results in Figures 1
and 2 indicate a corresponding rapid drop in C1C>2 concentra-
tion.
There have been no reports previously published concerning
disinfection of CSO with C1C>2, and only a limited number of
papers dealing with C1C>2 as a disinfectant57"60. There has
been some work done outside this country, but it was difficult
to assess the validity of the data.
Duplicate trials showed wide variations similar to the trials
with Cl2- This may be taken as an indication that the varia-
tions in chemical composition of the sample have a greater
effect on disinfection than any of the controlled factors
except time and dose. Based on the limited data, there may
be a slight effect of screening on disinfection with C102.
Both TC and FS showed adequate disinfection with 8 mg/1 on
screened samples while the unscreened samples required 16 rag/1
and greater than 25 mg/1.
Virology—The inactivation of 0X174 by C1C>2 in SCSO is shown
in Figure 17. Biphasic curves similar to Cl2 inactivation
curves were evident at the lower concentrations, and the
major part of the inactivation occurred in the first 120
seconds. Four mg/1 C102 reduced the count by 3.1 logs in the
first 120 seconds and only 3.15 logs in 300 seconds. This
suggests that, like C12, C102 was the primary disinfectant
and reacted completely with substances in the SCSO in 120
seconds. This same conclusion can be formed from the esr and
bacteriological studies. Virus samples were not taken at
longer time intervals so little can be said of the residual
antiviral activity of the reaction products, presumably C1C>2~.
The results of the inactivation of polio-1 in the same SCSO
are shown in Figure 18. Four mg/1 C102 reduced the count by
1.5 logs in 120 seconds. Eight mg/1 C102 caused a two log
reduction in the first 30 seconds. Higher dosages caused
reductions to below the reliable limits of the plaque assay
system. No background virus was detected in the SCSO.
60
-------
10* -
(Ti
1-4 10
o
£
of
leo 210 z«o rro 300
TIME. lecondi
120 150 tao 210
TIME, »«conOj
Z4O zro 300
Figure 17. Single-stage disinfection
of 0X174 with CI02
Figure 18. Single-stage
disinfection of
polio-l with CIC>2
-------
Clearly the polio-1 was much less sensitive to C102 than was
0X174 (compare Figures 17 and 18): 4 mg/1 C102 caused 3.0 log
reduction of 0X174, but only a 1.5 log reduction of polio-1.
No long-term residual C102 activity was noted for either virus.
These results represent the average for three trials. The
trial-to-trial variations were no more than twenty percent for
each time-dose point. As mentioned previously, screening has
no effect on virus reductions. The studies were carried out
using only 0X174 and polio-1 since it was felt that these
viruses were representative of most pathogenic species in
their response to disinfection.
The lack of references to disinfection of virus with C102 in
any media indicated that some preliminary studies were
necessary. The data in Table 18 shows the relative sensitivity
of several other viruses to C102 in SCSO. The experiments
revealed an apparent difference in sensitivity between envel-
oped viruses (HSV, NDV, YFV and vaccinia) and the two other
viruses. Four mg/1 C102 reduced the former by 2 logs and the
latter by less than one log. Eight mg/1 reduced HSV, NDV and
YFV by 5 logs or more under conditions which reduced ECHO-7
and possibly Coxsackie B-3 by less than a half log.
The relative sensitivity of various water-borne indicator
organisms in SCSO was compared (Figure 19). It is apparent
that the polio-1 was least sensitive and FS were less sensi-
tive than TC. 0X174 was considerably more sensitive than
either of the bacteria or the polio-1. Thus, although 0X174
may be an excellent virus for studying the kinetics of dis-
infection by C102, it is not a very good indicator for dis-
infection of CSO. C1C>2 has shown very similar rates of inac-
tivation against almost all of the animal viruses studied:
Coxsackie B-3, ECHO-7, HSV-L2, NDV, vaccinia and polio-1.
Viricidal activity against all of them stopped immediately
upon addition of thio.
The f2 phage was found to be a better indicator of viruses
than 0X174. Figure 20 shows typical inactivation curves
obtained when an f2 stock was diluted approximately 1:10~16
in SCSO and treated with C102. One can predict that 4 mg/1
C102 will inactivate about the same amount of f2 as polio-1
(1.3 logs).
In No-Demand Systems—C102 inactivation of virus in a no-
demand system serves as a useful baseline for studying the
kinetics of viral inactivation and for comparing C1O2 to
other disinfectants. It has the virtue of complete repro-
ducibility and is the most practical way to divorce the
62
-------
U)
Table 18. Survival of Viruses in SCSO Treated With C102a
C102
Dosage
(mg/1)
0
0.2
0.5
1.0
2.0
4.0
8.0
HSV-L2
(PPU/ml)
2.8X105
2.6X105
1.4X105
2.2X105
11.2X104
2.2X103
0
NDV
Calif.
(PFU/ml)
5.4X10°
8.6X106
5.0X106
4.2X106
1.1X106
0
YFV
(PFU/ml)
4.0X105
2.4X105
1.6X105
8.2X104
7.2X10^
4.4X103
0
Vaccinia
(PFU/ml)
4.2X10^
1.6X102
2.4X102
32
0
0
ECHO-7
(PFU/ml)
4.2X10°
4. 8X106
5.5X106
4.8X106
1.16X106
1.21X106
1.04X106
Coxsackie
B-3
(PFU/ml)
1.0X10°
8.4X105
1.0X106
1.2X105
^^ one minute contact time
-------
CTi
0 30 tO K> IZO ISO ISO 2W 24O 27O 3OO
TIME, MCOOdt
Figure 19. Single-stage disinfection
of several bacteria and
viruses with CIO2
Figure 20. Single-stage
disinfection of
f2 with CIO2
-------
direct effect of C102 on the virus from indirect effects via
the virus environment.
Polio-1 was purified by differential centrifugation and rate-
zonal centrifugation in sucrose in order to remove C102
demanding substances. All no-demand disinfection experiments
were run in sterile 0.01 M phosphate buffer at pH 7.0. The
resultant plots (Figure 21) show that for different concen-
trations of C1C>2, virus counts are an exponential function
of time. This suggests a pseudo first-order reaction as
would be expected from Chick's Law. Considerably less C102
was required to achieve virus levels comparable to those in
SCSO. Application of only 0.4 mg/1 ClC>2 for 300 seconds
inactivated 3.5 logs of polio-1. When all these individual
treatments from several experiments were converted to
standard dose (mg/1 x time of exposure) of C102 and plotted
against log numbers of survivors (Figure 22) , a straight-line
function was observed.
It is quite clear from these experiments that CSO rapidly
removes C1C>2 and there is little or no residual activity left.
While there is a considerable difference in the sensitivity
of viruses to C1C>2, even the most resistant viruses succumb
to tenths of a mg/1 under no-demand conditions. Furthermore,
the inactivation appears to be exponential with no apparent
drop in activity over long periods of time. In one experiment
under no-demand conditions, 0.2 mg/1 C102 continued to inac-
tivate 0X174 exponentially for 90 minutes before the experi-
ment was terminated. In SCSO, however, activity of up to 25
mg/1 C102 rarely lasted more than 30 to 60 seconds even at
the highest concentrations.
Effect of pH—In order to compare effects of different pH
values it was necessary to run the experiments under no-
demand conditions. Figure 23 is a detailed illustration of
pH effects on C1C>2 viricidal activity against 0X174. The pH
vs. PFU/ml of 0X174 survivors was plotted at three standard
doses of C102: 12 (0.4 mg/1 X 30 seconds), 24 (0.4 mg/1 X
60 seconds) and 72 (0.4 mg/1 X 180 seconds). The active pH
range lies between 4.5 and 7.5. The maximum antiviral
activity occurred at pH 4.5. Similar effects were observed
when the pH of SCSO was adjusted and seeded with 0X174.
The role of pH in Cl2 disinfection has been thoroughly
studied and is well documented47/48. It is thought that HOCl
is the disinfecting agent rather than the dissociated hypo-
chlorite ion (OC1~), or dissolved Cl2 gas. HOCl is a weak
acid (K=2.95 X 10~8) so a lower pH will favor the undissociated
form and, therefore, promote increased disinfection. This has
65
-------
CTi
TIME, seconds
STANDARD DOSE. sec. « mg/l
Figure 21. Single-stage disinfection
of polio-l with CIO2 in
a no-demand system
Figure 22. Standard dose
curve for
disinfection of
polio-l with CIO2
-------
SO 6O »O 12O ISO ISO 2IO 24Q 2 TO 3OO
Figure 23. Effect of pH on disinfection
of 0X174 with CI02
Figure 24. Effect of CI02 on
cell-associated polio-I
-------
been verified experimentally by a number of workers.
It requires four times as much Cl2 as C102 to inactivate
viruses in SCSO but this may be due to the fact that the pH
of SCSO is outside the optimum value of 2.5 for Cl2 disinfec-
tion. This is one of the main reasons for employing C1C>2 as
a disinfectant. It is a neutral compound and is effective
at neutral or slightly acidic pH. It is also more slowly
absorbed by the particulate fraction of SCSO than is
Cell-Associated Viruses_ — In addition to free virions, water-
borne animal viruses may be transported either inside or on
the surface of cells which have been excreted from the
intestinal tract of man and animals. The possibility that
under natural conditions these cell-associated viruses are
protected during C1O2 disinfection was tested by the following
experiment.
An infected cell inoculum was prepared which contained 4.9 X
106 PFU/ml of polio-1; 75 percent of this (3.7 X 106 PFU/ml)
was found to be cell-associated and 25 percent (1.2 X 10^
PFU/ml) was free, extracellular polio-1. Ten ml of the
inoculum was poured into 500 ml of SCSO, passed through the
23 micron screen, treated with C102/ neutralized and titered
for cell-bound and extracellular virus. Neither free or
bound virus was lost by this filtration.
Figure 24 shows the surviving cell-associated virus after
C102 treatment and chloroform extraction. An increase in the
expected number of survivors was noted. For example, 8 mg/1
C102 normally reduces free virus titers in SCSO by 2.2 logs
in 30 seconds: in Figure 24 the cell-associated virus was
only reduced by 1.15 logs. Thus, the presence of the cellular
material clearly interferred with the effectiveness of C102
treatment.
Source of Chlorine Dioxide Demand — Under no-demand conditions,
C102 shows linear inactivation curves for polio-2 and 0X174.
Under high-demand conditions found in SCSO, the activity
ceases after 30-60 seconds. The component' in SCSO which is
responsible for this neutralization of C102 is unknown. An
effort was made to detect this neutralizing component. A
sample of the highly contaminated first flush of a CSO was
treated in various ways to reduce demand: (1) autoclaving for
30 minutes at 121°C; (2) filtration through 0.45 micron
membrane filters and; (3) centrifugation at 40,000 rpm for
30 minutes. 0X174 purified in sucrose gradients was then
added to the samples and controls. Various concentrations of
C102 were added for 180 seconds and neutralized with thio.
The survivors are listed in Table 19.
68
-------
'-0
Table 19. Single-stage Disinfection With C102 in CSO Treated to Remove Demand5
Centrifuged 40
C102
(mg/1)
0.0
0.2
0.5
1.0
2.0
4. 0
6.0
Untreated
CSO
100
47
11.
5.
0.
0.
4
3
001
0005
Filtered
0.45U MF
100
62
32
0.62
0.002
0.008
,000 rpm, 30 min
15
psi
Pellet Resuspended 30 min.
Supernatant in Phosphate Buffer Autoclaved
100
45
14
0.
0.
0.
13
0001
0006
100
82
67
1.
0.
0.
3
012
007
100
46
13
0.
0.
0.
11
001
0005
Phage in
Phosphate
Buffer
100
33.
15.
0.
0.
0.
""
7
9
2
0015
00007
a values in percent 0X174survivors
-------
These data indicate that the small particulate fraction of
CSO exerted a strong demand on C1C>2, especially at concen-
trations of C102 higher than 2 mg/1. For example, at 4 mg/1
C102 the inhibitory activity was reduced in the supernatant
fraction but was not removed greatly by filtration. The
resuspended pellet strongly interfered with the activity of
C102, again showing the particulate nature of the inhibitory
component. Autoclaving destroyed a large amount of inhibitory
component, perhaps by precipitating particulates or reducing
their surface area. It is; not known what particulates are in
CSO, but it is possible they are inorganic materials. An
effort will be made in the future to collect them by high-
speed centrifugation after filtration, to make a chemical
analysis, and to examine them by electron microscopy.
Other Parameters—The preliminary results of the effect of
C102 on ATP were given in Table 13. The majority of the ATP
study is discussed in a later section dealing with two-stage
disinfection. The effects of C102 on pH, TOC and NH3N were
found to be negligible in the dosages used in this study.
Mechanism of Disinfection—
In a manner analogous to Cl2, C102 is a much more powerful
disinfectant than its decomposition product C102~- Therefore,
the same type of biphasic curve, with a rapid initial drop
followed by a gradual decrease, is observed. In this case,
this gradual decrease is almost flat, reflecting the weak
bactericidal and viricidal properties of C102~.
The chemical mechanism(s) involved in the disinfection action
of C102 in water is unclear. Ridenour and Ingols61 reported
that C102 (1) reacts with the large colloidal molecules of
peptones following the laws of surface absorption, (2) does
not react with NH3N, urea, glucose, or alcohols, and (3)
reacts with phenols to about the same extent as does Cl2 but
much more slowly. They hypothesized that as a bactericide,
C102 has an advantage over Cl2 in that it is less reactive
to substances in the water.
As is the case with Cl2, the exact mechanism of C102 attack
on bacteria and viruses is unknown. Bernarde58 showed that
C102 does not rupture the bacterial cell walls but this is
all that is known. The same observations about lipid con-
centrations and disinfectant sensitivities that were made for
C12 can be made for C102. The fact that on a molar basis
C102 is more effective than Cl2 implies that there is an
increased sensitivity of the lipids when C102 is used. This
could also explain the observation that the spread in bacteri-
70
-------
cidal and viricidal properties for high and low lipid contain-
ing organisms is greater with C102 than Cl2.
Ejffects of Screening—
Since disinfection with C1C>2 was affected by screening while
disinfection with Cl2 was not affected, there must a differ-
ence in the nature of the disinfection reactions. If the
same materials that made up the Cl2 demand also made up the
C102 demand, as has been previously hypothesized, identical
screening effects on disinfection should be observed. To test
this hypothesis, a sample of SCSO was split into two portions
with the Cl2 and C1C>2 demands determined on each portion.
Within experimental error the values came out approximately
the same. The sample for which the Cl2 demand had been
determined was now dechlorinated by titration with thio to
the starch-iodine endpoint. The C1C>2 demand of this sample
was now found to be 80% of the C102 demand of the original
sample. Thus, the two demands must be partially due to the
different materials.
It is surmised that the C1C>2 demand is due to dissolved
organics, which unlike the CDS, are not found encapsulated
within the solids. Thus, screening does little to the C102
demand but only exposes more bacteria to the disinfection
process and thus promotes C102 disinfection. As further
proof, settling actually reduces the Cl2 demand but leaves
the C102 demand unchanged, as shown in Table 20.
Table 20. Effect of Solids Removal on Disinfection with
C12 and CIO?
Sample
SCSO
scsoa
SCSO-settled
Cl2 Demand
6.5
0.0
3.5
C102 Demand
6.0
5.0
5.2
a carried to breakpoint and dechlorinated
Temperature Effects
In addition to the climatic reasons for studying the effect
of temperature on disinfection, previous work on this sub-
ject has shown definite temperature effects62'63
Bacteriology--
The bacterial results of this study are given in graphical
form in Figure 25 and in tabular form in Appendix B. There
71
-------
NJ
SAMPLE INFORMATION
BLENDED
UNSCREENED
PH 6.89
Clt DEMAND 8OO
TIME, seconds
12O ISO I8O 210 24O 2TO
TIME, seconds
TC VS CI2
FS vs
Figure 25. Effect of temperature on disinfection of bacteria
-------
SAMPLE INFORMATION'
BLENDED
UNSCREENED
PH &69
CIOJ DEMAND B.OO
-0
OJ
I I I I I I I
SAMPLE INFORMATION*
BLENDED
UNSCREENED
PH cas
CIO, DEMAND *OO
120 I9O IflO 21O 2«O 2TO SOO
TIME, second*
120 190 180 210 240 2TO SOO
TIME.itconds
TC vs. CI02
FS vs. CI02
Figure 25. Continued
-------
may be a slight increase in efficiency with increasing temp-
erature but the effects of time, dose and sample composition
are much greater. Previous studies of no-demand systems and
drinking water supplies show a much greater enhancement of
disinfection at higher temperatures with both C±2 and
C10263. In SCSO these effects were still measurable, but
notably decreased. The much shorter contact times used in
this study and competition from disinfectant demands should
have this effect.
Virology--
The results of the temperature variations on viral inactiva-
tion are presented in Table 21. A 40 percent difference in
activity was observed between the 60 second and 300 second
exposures to C102 at 4°C; no difference was seen at the higher
temperatures. This indicates that although the initial rate
of disinfection may be reduced at colder temperatures, the
total disinfection achieved is the same.
Table 21. Effect of Temperature on Disinfection of Polio-1
with C102a
Percent Reduction of Polio-1
Temperature (°C)
4
12
22
35
60 seconds
39.5
63.7
66.1
72.8
300 seconds
82.5
68. 6
78
78.8
-a 4 mg/1
A more detailed study was conducted with 0X174. Figure 26
is a graph of phage survivors vs. temperature at a constant
dose of 4 mg/1 C102 . Although the points show considerable
scatter, a trend line fitted by the method of least squares
supports the above observations with polio-1 that there is
only a slight increase in C102 activity with increasing
temperature. The magnitude of the temperature effect is
seen from the fact that there was less than one log differ-
ence in the number of phage survivors treated at 0°C and 45°C.
The most profound temperature effect was seen with the inacti-
vation of f2 under no-demand conditions (Figure 27) . At a
concentration of 2 mg/1 C102 for 180 seconds, an apparently
exponential increase in activity of C102 was observed. From
an initial concentration of 1 X 107 PFU/ml, the virus titer
dropped to 3.9 X 10^ PFU/ml at 45°C, but at 0°C, 1.6 X 105
PFU/ml were recovered. Although this experiment has been
performed only once, it suggests that the reaction mechanism
74
-------
1C* I
Ul
4...
«*fl/l CI02
FOR flO SECONDS
2i*ig/l CI02
FOR 180 SECONDS
10 20 JO *0
TEMPERATURE. -C
TEMPERATURE. 'C
Figure 26. Effect of temperature on
disinfection of 0X174 in
SCSO
Figure 27. Effect of temperature
on disinfection of ^
in a no-demand
system
-------
or the sensitive sites of the virus are markedly different.
Recent experiments have shown that under the same no-demand
conditions, temperature and exposure time, only 0.8 mg/1 C102
are required to inactivate the same number of infective units
of polio-1 that 2 mg/1 C102 does with f2 phage. Under demand
conditions, the competition between the organic background
and the virus is so great that the temperature effects are
largely unseen except at 4°C (Table 21).
Comparison of Chlorine and Chlorine Dioxide
Bacteriology--
Disinfection, as measured by TC kills, reached acceptable
levels 50 percent of the time with 8 mg/1 C1C>2 and 25 mg/1
Cl2- There is no comparative information in the literature
for CSO. Generally, it has been shown in previous
studies58'60 that C102 is a better bactericidal agent than
Cl2 in no-demand systems and drinking water.
Virology--
The relative inactivation strength of the Cl2 and C1C>2 toward
virus is illustrated more or less directly in Figure 28. A
dosage of 4 mg/1 C1C>2 inactivated as much f2 phage as 20 mg/1
Cl2, suggesting that on an equimolor basis the C1C>2 is about
ten times as active a viricide as Cl2 when they are diluted
with water which has both a Cl2 demand and a C1C>2 demand
In these studies an attempt was made to discover whether it
is feasible to substitute C102 for Cl2 as a viricide and to
determine the best method of utilizing C102 as a viricide in
the treatment of CSO. On the basis of these data it appears
that C102 is a satisfactory alternative to Cl2 for disinfec-
tion of viruses. The C102 activity is relatively constant
over a wide range of changes in pH, temperature and ionic
requirements. It inactivates viruses very rapidly and has a
wide spectrum of viricidal activity. No truly resistant
virus has been found to date and no resistant phage mutants
have been observed. The C102 demand of heavily contaminated
water is slightly less than the Cl2 demand. This lengthens
the working life of the disinfectant and reduces the dosage
needed. Although the degradation products of C102 in CSO
and other crude waters are not known, there is no evidence
that appreciable quantities of chloramines are found.
Discussion--
From these studies it would appear that C102 is a better dis-
76
-------
I06
105
c: io4
Q.
C\J
10'
I
I
30 6O 90 120 150 180 210
TIME, seconds
240
270
300
Figure 28. Comparison of disinfection of ^2 w'th CI02
and CU
77
-------
infectant than free C3-2 whenever disinfection is to be carried
out by these two species, i.e., in pure cultures, drinking
water or high-rate disinfection of sewage. In contaminated
waters with a significant disinfectant demand, the Cl2 and
C102 are rapidly converted to combined Cl2 and C1O2~, respec-
tively. Thus for long-term disinfection in these waters, the
comparison is between these latter two species. Since C102~
has less disinfection ability than most forms of combined C12,
chlorine is the choice under these long-term conditions.
Economic considerations of the operating costs alone indicate
that Cl2 is the cheaper of the two, even employing the higher
doses. Cl2 as the gas or as sodium hypochlorite costs much
less than C1C>2 on a per pound basis. Even with the higher
dosages necessary in this study, disinfecting with Cl2 would
be less expensive. This subject will be dealt with in
greater detail in a later section of this report.
The effects of the decomposition products on the receiving
waters must also be compared. Cl2, either free or combined,
is known to be toxic to many species of fresh-water fish at
the microgram per liter (ug/1) level^^'"^. However, when
compared to the dangers to human health of untreated CS065
and given the relatively short half-life of Cl2 in most
receiving waters, the risk of fish kill may be the best alter-
native. It may not be feasible to dechlorinate the CSO prior
to their discharge since the outfall pipeline often serves as
part of the contact chamber.. Little is known of the toxic
effects of C1C>2~ on marine life, although low concentrations
(less than 1 mg/1 C102~) have caused difficulties in some
studies"".
The proper weighing of these three factors, disinfection
efficiency, cost and toxicity of receiving waters, requires
careful evaluation than can better be made after the full-
scale facilities have been operated.
TWO-STAGE DISINFECTION
The two-stage disinfection study consisted first of sequential
addition of two doses of C102 and then a single dose of Cl2
followed by a dose of C102. Reductions in ATP were measured
in parallel with bacterial reductions to determine the validity
of using ATP as an indication of disinfection.
Sequential Addition of Chlorine Dioxide
Bacteriology--
The sequential addition of more than one dose of Cl2 is known
78
-------
to have the same effect as a single dose equaling the cumula-
tive amount of Cl267. Therefore, two-stage addition of C1C>2
was studied to determine if C1C>2 behaved similarly to Cl2.
The bacterial results are presented in Figures 29 and 30,
with the corresponding tabulated data in Appendix D. For the
present, the discussion of ATP is deferred but will be taken
up in detail later in this section. Ideally, there should
be a stepwise reduction in bacteria at the times corresponding
to the addition of C102. However, the plots tend to be
smooth curves that are quite similar to the single-stage
curves. A possible ''explanation for this is that the intervals
between dosages, either 15 or 30 seconds, are short enough
that complete mixing of the first dosage cannot be completed
by the time the second dosage is added. Stepwise reduction
should be observed if longer intervals between dosages were
used, but in high-rate disinfection, this is not feasible.
The comparison of the results in Figures 29 and 30 with the
single-stage results in Figures 15 and 16 show the same
reductions with either one- or two-stage addition of equal
amounts of disinfectants. This observation is consistent
with the proposed mechanism for C1C>2 disinfection and indicates
that the rate of disinfection is a linear function of dosage.
Virology--
Figure 31 compares the inactivation of 0X174 by addition of
five mg/1 C102 to the addition of five sequential one mg/1
dosages at 30-second intervals. It is apparent that much of
the effective activity of the large single dosages is lost
before it can be mixed completely. It should be noted that
the mixing for the single dose was less vigorous than for
the other additions of disinfectants in this and other experi-
ments. This further illustrates the need for thorough mixing.
It is likely that in the small region of disinfectant contact
there was a rapid, complete viral kill that resulted in the
steep initial drop in Curve 1 of Figure 31. However, there
also may have been enough C102 demanding substances to con-
vert all the C102 to C1C>2~. The experiment was not repeated
with a more rapid mixing of a single, large dose of C102-
Multiple small doses with thorough mixing may be a more
economical way to treat the water.
Although the plaque counts at 150, 180 and 210 seconds are
only approximations due to the small number of surviving
viruses, it appears that there was a second factor which
provided some protection for the virus. Each additional dose
was less effective than the preceding one. A variety of
explanations are possible: clumping of viruses, genetic rescue
79
-------
10'
2mg CIO at0 seconds
I z
2m«
Znvg CI OjatO seconds
2tng CI02" 15 "
2mg CIO at 0 seconds
2 gig CIQg ' IS
2 mg CIO at 0 second*
2rnq CI02 '= 15
3O 6O 90 120
TIME, seconds
30 60 90 120
TIME, seconds
30 60 90 120
TIME,seconds
30 60 90 120
TIME,seconds
TOTAL COLIFORM
FECAL COLIFORM
-•-- FECAL STREP
Figure 29. Two-stage disinfection of bacteria and ATP
with CI02 (I)
80
-------
4 tng/l ClOg at 0 seconds 4 mg/l CI02 at 0 saconds 4 mg/l CI02 at 0 seconds 4 mg/l ClOg at 0 seconds
0 30 60 90 120
TIME, seconds
0 30 60 90 120
TIME, second
0 30 60 90 120
TIME, seconds
0 30 60 90 120
TIME,seconds
TOTAL COLIFORM
FECAL COLIFORM
FECAL STREP
Figure 30. Two-stage disinfection of bacteria and ATP
with CI02 (II)
81
-------
ARROW INDICATES ADDITION OF I mg/l CI02
*.
KEY
CI02 DOSAGE
I mg/l SEQUENTIAL ADDITION
5 mg/l SINGLE ADDITION
30 60 90 120 150 180 210 240 27O 300
Figure 31, Addition of multiple doses of CI02 to 0X174
82
-------
as a result of interaction of two disabled particles,
membrane barrier effect, reinfection by viruses in a pro-
tected corner of the vessel, etc. The most likely explanation
seems to be that the curve represents the progressively less
efficient mixing in which the same proportion of viruses is
out of reach of the C1C>2 each time disinfectant is added.
Chemical Parameters—
Two-stage addition of any combination of disinfectants had
no effect on any of the chemical parameters. All of this work
was conducted on screened samples.
Chlorine Followed by Chlorine Dioxide
Bacteriology—
The second part of the two-stage study was the sequential
addition of different disinfectants. This could enhance dis-
infection in two ways. The first disinfectant could pre-
condition the waste so that the second disinfectant could
work more efficiently. This possibility has already been
suggested when Cl2 is used as the first agent, followed by
C1C>2^. The second possibility is that interactions between
the two disinfectants could lead to increased efficiency by
either or both agents.
The bacterial reductions are given in Figures 32 and 33, with
tabulated data in Appendix D for Cl2 followed by C1C>2. Varying
the interval between dosages from 15 to 30 seconds did not
affect the results, presumably an effect of incomplete mixing
as explained previously- The three test bacteria groups
(TC, FC, FS) behaved in a similar manner. Although the TC
levels were reduced to an acceptable value, as was also found
in single-stage studies, some of the initial values were one
log less than in the single-stage studies. Therefore, the
final values tend to be somewhat misleading and the incremental
log reductions at corresponding times should be compared.
In order to determine if disinfection has been enhanced beyond
the additive effects of the different agents, the log reduc-
tions must be compared. Table 22 includes the log reductions
in TC accomplished by 4 mg/1 and 8 mg/1 Cl2, and 2 mg/1 and
4 mg/1 C1O2 as is determined in the single-stage study from
Figures 11 and 15, respectively. The sums of the reductions
are compared to the observed log reductions in the two-stage
studies for the appropriate dosages for TC bacteria in
Table 23.
83
-------
I07
4 mg/l CI2 ot 0 Mcondi 4mg/l Clg ot 0 Mcoodi
2 " ClOg " 15 " 2 " ClOg " 30 "
4mg/ICIg ot 0 taconds 4 mg/l Clg at 0 seconds
4 " CI02 "15 " 4 " CI02 " 30 "
o
X
g I04
I03
j I
30 60 80
TIME, seconds
SO SO 90 120
TIME, seconds
SO 60 90
TIME, seconds
120
JO 60 90 120
TIME, seconds
TOTAL COLIFORM
FECAL COLIFORM
Figure 32. Two-stage disinfection of bacteria and ATP with
CI2 and CI02 (I)
84
-------
8mg/l CI2 at 0 seconds
2 " CI02" 15 "
8 mg/l CI2 ol 0 seconds
2 " CI02 " 30 "
Bmg/l Clg at 0 seconds
4 " ClO" 15 "
8 mg/l CI2 at 0 seconds
4 " CI02" 30 "
3O 60 90
TIME, seconds
30 6O 9O
TIME, seconds
120
30 60 90
TIME, seconds
0 30 6O 90 120
TIME, seconds
TOTAL COLIFORM
FECAL COLIFORM
FECAL STREP
Figure 33. Two-stage disinfection of bacteria and ATP
with C\2 and CI02 (H)
85
-------
Table 22. Average Bacterial Reductions for Single-stage
Disinfection
Disinfectant
C12
C12
C102
C102
Dosage
(mg/1)
4
8
2
4
Time
(Seconds)
120
120
90-105
90-195
Log Reduction
0.5
1.0
1.0
1.0
Table 23. Average Bacterial Reductions for Two-Stage
Disinfection
Log Reduction
First Dosage Second Dosage at 120 Seconds
Disinfectant (mg/1) Disinfectant (mg/1) Predicted Observed
ci2
Cl2
C12
Cl2
4
4
8
8
C102
C102
C102
C102
2
4
2
4
1.5
2.0
2.0
2.5
1.5
1.5
3.0
4.0
At low reductions there is no significant difference between
observed and predicted values, most likely because of diffi-
culties in measuring small differences in large numbers. As
the reliability in reported differences increases, the
enhancement of disinfection becomes more easily discernible.
Because of the variations in disinfection in different samples
of SCSO observed in the single-stage disinfection, these
results can only be considered as indicators of a two-stage
effect. Many such observations must be made before any
definitive statements can be issued.
Virology—
Samples of SCSO containing 0X174 were treated with 8 mg/1 C12
for 120 seconds and then 2 mg/1 C102 was added. As shown in
Figure 34, both disinfectants were tested separately and in
combination as controls. Eight mg/1 C12 and 2 mg/1 C1O2
both reduced the titer of 0X174 by 2.2 logs in 300 seconds.
When both were added simultaneously, the virus titer was
reduced by 4.4 logs in 300 seconds. However, when C12 was
added first and then C102, the virus titer was reduced by
5.3 logs. Thus, there would appear to be an advantage to
sequential as opposed to simultaneous addition of disinfec-
tants. This work was confirmed repeatedly and the experiment
was enlarged as shown in Figure 35. C102 and C12 were added
86
-------
10*
KEY INTERVAL
SYMBOL °°%ffi' wcoods
0 8CI2:2CI02 130
-*— 2CI&2 -
-*- 8 CI2: JCIOj 0
120 ISO 180
TIME, seconds
270
Figure 34. Comparison of single
disinfection of 0X174
-stage and two-stage
with CI2 and CI02
87
-------
I09
10'
10s-
U.
QL
I03
10'
10
12 REPLICATES
UNTREATED
Cl2 8
CI02 2 mg/l
INTERVAL 30 seconds
CONTACT TIME 300 seconds
Tt
REPLI-
CATES
-TTh
REPLI-
CATES
TT
REPLI-
CATES
REPLI-
CATES
I. CI2'.CI2 CI2'-
2-STEP TREATMENT
Figure 35. Repeatability of disinfection of 0X174 with
and CI02
88
-------
in dosages sufficient to provide identical kills of 0X174
(8.0 mg/1 Cl2, 2.0 mg/1 C102) when added to SCSO. The dis-
infectants were added sequentially at 30-second intervals to
seeded SCSO and neutralized with thio for subsequent virus
enumeration. Four combinations were studied: Cl2 followed by
C102, C102 followed by Cl2/ C102 followed by C102, and Cl2
followed by Cl2- Despite the fact that single-stage addition
of Cl2 and C102 gave identical amounts of inactivation, two-
stage addition of Cl2 was less effective than two-stage addi-
tion of C102. A possible advantage of Cl2 followed by C1C>2
as compared to C102 followed by Cl2 may be seen in Figure 35.
Mechanism of Disinfection
A possible interpretation of these data suggests that the
bactericidal and viricidal properties of both Cl2 and C1C>2
may depend on the length of a free residual. If Cl2 is more
rapidly neutralized or absorbed than C102, it would be more
difficult to maintain residual free Cl2 by multiple dosage
techniques. The two-step inactivations in Figure 36 show
that the rate of inactivation for the second viricide is very
much reduced, regardless of whether it is the same as the
primary reagent. The second dose continues to kill for a
longer period of time, 60-90 seconds, than the primary dose
for both Cl2 and C1C>2 • This suggests that reactive sites or
sensitive particles become exposed in the resistant population.
If the free residual is maintained, these exposed particles
are killed.
As indicated in Table 20 the Cl2 and C102 demands are due to
an interaction between the two disinfectants. The interaction
could take place through the following mechanism. One of the
reactions for the preparation of C102 involved the addition
of Cl2 to a solution of C102~-7
H+ + HOC1 + 2NaC102 — 2C102 + NaCl + Na+ + H20
It can be hypothesized that after the C102 has been oxidized
to C1O2~ in SCSO, any free Cl2 also present might reduce C102~
back to C102- This process would prolong the existence of the
more potent disinfectant, C1O2/ and thus enhance disinfection
beyond that expected by the sum of the respective concentra-
tions of Cl2 and C1O2. It might be argued that the reduction
in free Cl2 would compensate for the extra C102 but it has
been shown that C102 is a more powerful disinfectant when
taken on a weight basis.
If combined Cl2 is also capable of reducing C102~ to C102, the
process would be a cyclic one continuing until all the Cl2,
89
-------
10* -
KEY
SYMBOL DOSAGE
mg/l
— X — BC\2- 2 CI02
—A— 2 ClOj: 8 Cl2
— 0- 2CI02' 2 CI02
B 8 CI2'.8CI2
INTERVAL
seconds
30
30
30
30
3O 60 9O 120 150 180 2IO
TIME, seconds
24O
27O
3OO
Figure 36. Two-stage disinfection of 0X174 with
and CIC>2
90
-------
free or combined, was converted to chloride (Cl~). However,
it is not expected that the combined Cl2 has sufficient
reducing power to accomplish this reaction.
If this hypothesis is correct, the free Cl2 will undergo
competitive reactions between the C102~ and the Cl2 demand.
Thus the greater the amount of Cl2/ the greater the expected
enhancement. Although this was observed, the numbers of
combinations were not sufficiently great to prove the issue.
The enhancement effect would be increased by any means that
would increase the free Cl2 concentration. In the bacterial
studies, Cl2 was added 15 to 30 seconds prior to the addition
of C1C>2/ allowing the Cl2 demand to be exerted for 30 seconds,
thus decreasing the free Cl2 concentration. This minimized
the regeneration effect, but some regeneration should have
taken place since it is known that the free Cl2 requires
longer than 30 seconds to disappear.
The virus studies do not verify this theory. The simultaneous
addition of Cl2 and C1C>2 should have given greater enhancement
than delayed addition of C102- However, the result was only
an additive effect of both dosages. It is suggested that esr
be used to detect an increase in C102 concentration after the
addition of Cl2 as an absolute verification of the concept.
Little clarification of the issue would result from studies
of bacteria in no-demand systems. Any free Cl2 added to such
a system would remain as free Cl2- Also the C102 would not
be converted to C102~ so regeneration is impossible. If the
regeneration of C102 cannot be substantiated, the explanation
of enhanced disinfection must lie in some other interaction
of Cl2 and C102« Whatever the reason, this two-stage effect
should most certainly be studied in greater detail in future
bench- and full-scale operations.
ATP CORRELATIONS WITH BACTERIA
The measurement of ATP was added to the two-stage disinfection
studies to determine if this parameter would yield the same
bactericidal information as was obtained through direct bac-
terial measurements and, therefore, yield a reliable control
signal for disinfection. Examination of Figures 29, 30, 32,
and 33 shows that for all trials in which the TC count was
greater than 1000 per 100 ml after two minutes contact time,
the ATP value was greater than one arbitrary unit. Identical
ATP standards were used to calibrate the instrument for each
trial, so the arbitrary units were the same for all trials.
Similar observations can be made using 200 counts/100 ml for
FC and FS. Table 24 gives the correlation between ATP and
TC and FC. The large fluctuations in initial ATP values led
91
-------
to the conclusion that better correlations might be obtained
with lower values. As would be expected, the correlations
are better for disinfected samples in which the bacterial
counts and ATP concentration are relatively low. This is
most likely due to the fact that TC were chosen as indicator
bacteria because they are relatively resistant to disinfection.
Therefore, in disinfected samples, the TC comprise a higher
percentage of the total bacterial population than in non-dis-
infected samples. At ATP levels less than one arbitrary unit,
the lower correlations most likely result from the lack of
precision in low bacterial counts. However, for all ATP less
than 0.5 unit, the TC were, with one exception, less than
1000 counts/100 ml. Thus, some ATP level can be selected as
an indicator of successful disinfection.
Table 24. ATP Correlation Coefficients
Range of ATP (Arbitrary Units)
0-50
15-50
0-15
0-1
TC
0.700
0.206
0.842
0.387
FC
0.759
0.515
0.794
0.346
The coefficients were calculated from the points in Figures
29, 30, 32 and 33. It is recognized that this data is only
a small fraction of the amount of work that must be performed
in order to reach any definitive conclusions about ATP and
bacteria correlations. However, there would appear to be
sufficient justification to study the possible use of ATP
as a monitor to control disinfection.
Application as a Control for Disinfection
The most common method of controlling disinfectant (usually
Cl2) dosages is the monitoring of residual disinfectant to
maintain a fixed level in the treated effluent, a method that
admittedly has its limitations68. Other methods include
addition based only on flows and, in larger plants, periodic
bacterial counts, but only as feedback information. These
methods may be acceptable in sewage treatment plants in which
the microbial variations are somewhat predictable, but totally
unacceptable for CSO treatment facilities in which the varia-
tions are large and unpredictable. The objection is that
simply maintaining a fixed volumetric residual does not
guarantee that the bacteria and virus have been reduced to a
safe level. ATP is a more direct reflection of microbial
activity than residual disinfectants.
92
-------
Before the development and testing of an in-line ATP monitor,
there are several difficulties that must be overcome. These
include the stability of reagents, adequate sampling tech-
nique, availability of the necessary electronics and the auto-
mation of the chemistry. However, the feasibility of such a
system is an accepted fact69. A continuous flow monitor is
envisioned with periodic switching from CSO to ATP for stan-
dardization. The control signal for addition of disinfectants
could be generated from an ATP monitor located after disin-
fection. This arrangement would require that the ATP con-
centration be kept below some pre-determined safe level.
Another possibility would be to measure ATP before and after
disinfection to detect sudden increases in degree of conta-
mination as well as residual ATP levels. The electronics
necessary to continuously record the light intensity from
the bioluminescent reaction have already been developed^.
The procedures for a continuous, automated extraction are
already in use in several of the "Technicon Methodologies"^8.
The expense of the reagents is likely to be quite significant
because of the high cost of removing the necessary enzymes
from actual firefly lanterns. The cost factor should most
definitely be studied in greater detail before attempting to
develop a monitor.
Stability Tests
The stability or storage life of the reagents must be at
least one week to realistically consider monitoring. Accord-
ingly, the stability of an ATP standard was tested under a
variety of conditions; namely, in the dark, under refrigera-
tion and with buffers added.
Eight sets of ATP standards were prepared as follows:
Cuvette Number (see Table 25)
1. ATP = 1.0 X 1CT1 ug/ml; EDTA=0; MgS04=0
2. ATP = 1.0 X 1CT1 ug/ml; EDTA=1Q-2M; MgS04=0
3. ATP = 1.0 X 10"1 ug/ml; EDTA=10~3M; MgSC>4=0: recommended
by DuPont32 for added stability
4. ATP = 1.0 X 10"1 ug/ml; EDTA=10-4M; MgS04=0
5. ATP = 1.0 X 10"1 ug/ml; EDTA=0; MgS04 = l()-4M: not pre-
pared due to difficulty in adequately dissolving MgS04
6. ATP = 1.0 X 10"1 ug/ml: EDTA=0; MgS04=10~2M:
recommended by DuPont32 for added stability
7. ATP = 1.0 X 10"1 ug/ml; EDTA=0; MgS04=10~3M
8. ATP = 1.0 X 10"1 ug/ml; EDTA=10~3M; MgS04=10-2M
The Biometer was calibrated each day with fresh ATP prepared
within one hour of use. Frozen (1°C) and unfrozen (ambient,
93
-------
Table 25. ATP Stability Experimenta
VD
Cuvette
Number
1
2
3
4
6
7
8
Cuvette
Number
1
2
3
4
6
7
8
Day 0
Frozen
1 .
1 .
n.
n.
1 .
1 .
0.
OOX10~X
94X10"3
71X10"1
81X10"!
44X10-1
54X10"!
96X10"!
Standingn
1.
1.
0.
0.
1.
1.
0.
Day
Frozen
0.
1 .
n.
n.
1 .
1 .
0.
89X10"-1-
07X1Q-3
82X1Q-1
88X10"1
27X10"!
53X10"1
73X10-1
00X1 (J^-
94X10"3
71X10-1
81X10-1
44X10"1
54X1Q-1
96X10"1
3
Day 1
Frozen
0.95X10 -1
0.76X10-3
0.89X10-1
0.90X1Q-1
1.00X10"1
1. 16X10-1
0. 83X1Q-1
Standing
0.
0.
0.
0.
0.
1.
0.
Standing
0.
1.
0.
0.
0.
0.
0.
98X1Q--1-
20X10~3
19X1Q-!
88X1Q-!
87X10"1
97X10-1
78X10-!
87X1Q--1-
87X10~3
75X1Q-!
74X10-!
95X10"1
02X10-1
80X10"!
Day 2
Frozen
0
8
1
0
1
0
Frozen
0.
0.
0.
0.
0.
0.
0.
95X10
97X10
73X10
97X10
93X10
91X10
65X10
.85X10"1
b
.02X10"!
.09X10"1
.98X10-1
.68X10-1
.76X10-1
Day 4
-3
-1
-1
-1
-1
-1
Standing
0.
0.
0.
0.
0.
0.
0.
88X1Q--1-
97X10~3
77X10-1
92X10"!
80X10"!
83X10-1
81X10-1
Standing
0.
0.
0.
0.
0.
0.
79X10"^
c
66X10"1
79X10"1
81X10"!
81X10"!
73X10-1
a ATP values expressed in ug/ml
b inaccuracies of maximum number of injections (6) show values vary by a factor of
100 or greater
c Sample cuvette destroyed in storage
-------
22°C) samples were both kept in the darkness until use. The
frozen samples were thawed in ambient temperatures and dark-
ness 45 minutes prior to use. All eight sets of ATP stan-
dards had respective frozen and unfrozen test samples.
The sample ATP standards were measured in accordance with
instructions in Luminescence Biometer Instruction Manual-^ .
All values (Table 25) are the average of two consecutive
readings of + 0.15, or that of a maximum of six readings of
the same exponential factor which did not fall within such
a range.
Cuvettes containing sample ATP standards #1 and #8 seemed to
show markedly greater stability under both frozen and ambient
temperature conditions. Sample #1 contained no buffers,
while sample #8 contained 10~3 EDTA and 10~2M MgSC-4. Both
values were recommended as optimal for stability in the DuPont
Instrument Manual.
The stability of the luciferin-luciferase reagent was investi-
gated in a similar manner. It was found that liquid reagent
could not be kept for more than two days under any conditions,
as shown in Table 26.
Table 26. Enzyme Stability Experiment
ATP Activity (ug/ml X 10"1)
Storage of Reagent Day 0 Day 1 Day 2 Day 3 Day 4
Fresh
Dark,
Dark,
Dark,
Light,
(Control)
Frozen
Refrigerated
Ambient
Ambient
0.
0.
0.
0.
0.
93
93
93
93
93
0.
0.
0.
0.
0.
89
86
61
68
80
0
0
0
0
0
.93
.71
.60
.74
.64
0.
0.
0.
0.
0.
85
84
14
31
03
0.
0.
0.
0.
<0.
85
98
07
14
01
Although this is a negative finding , the enzyme reagent as
prepared in this study was in its purified dissolved form.
The crude extract which should be suitable for an automated
procedure may be more stable. The technology required for
an automated ATP monitor has already been demonstrated. The
primary concern at this point is the correlation of ATP and
bacterial reductions on a wide scale.
IMPACT STUDIES
Aftergrowth
Bacteriology—
The results of the tank tests to determine bacterial aftergrowth
are presented in Figures 37 and 38 and
95
-------
5
cc
o
23 MICRON SCREEN
— 23 mg/l CI2 fof
— 25 " ' ' 6O
TIME, noun
TIME, houri
Figure 37. Aftergrowth of TC in receiving water
-------
UNSCREENED
12 mg/l CIO 2 to 30 nco™«
12 " " • 60 •
TIME. hour«
Figure 37. Continued
23 MICRON SCREEN
12 mg/l CIO2 for 30
12 " • '60
-------
00
Z5 mg/l CI2 for 30
25mg/ICI2 tor 60
UNSCREENED
TIME, hourt
10001-
25 mg/l CI2 'or 30 ucondi
• 25 mg/ I Clj for GO Mcondt
MICRON SCREEN
24 56
«0 Tt
TIME, hourt
Figure 38. Aftergrowth of FS in receiving water
-------
12 m0/l OOj for 30 aank
12 mg/l ClOj lor SO Mcandl
TIME. hour.
Figure 38. Continued
i
i
o
12 mg/l CIO2 'or JO
12 mo/C ClOj 'or 6O
23 MICRON SCREEN
I M
TIME, hour.
-------
Appendix E. The initial bacterial counts at time 0 in
Figures 37 and 38 were calculated by using the dilution
effects of the lake and averaging the appropriate lake and
creek counts. All values in Appendix E at time 0 in the
lake and creek were obtained by calculations. FC were run
in the first trial but were dropped from the remaining three
trials because all samples had zero counts.
Figure 37 shows a rapid die-off of most of the TC that enter
the lake. Some regrowth is observed but the counts never
reach the levels initially present in the lake control. The
die-off is hard to explain since the disinfectant residuals
were below 10 ug/1, the minimum detectable level, and every
attempt was made to promote bacterial life. The fact that
similar die-offs were observed for the controls raised
serious doubts as to the reliability of the studies.
One cannot determine if the die-off in the controls occurs in
the lake because of the continuous input from the treatment
plant. In view of the dilution factor of greater than 100:1
and the lake residence time of 50-200 days, the numbers
in the lake outlet (100 to 200 counts TC/100 ml) imply that
the lake supports bacterial life^. However, this claim could
not be verified experimentally.
The FS showed a similar die-off, but no aftergrowth of these
organisms was noted. Aside from giving different initial
lake values, there appeared to be little effect on aftergrowth
from screening, dosage, or type of disinfectant.
Virology--
The creek and lake water used in these studies were assayed
for background viruses at the same dilutions as in the dis-
infected samples, and none were detected. A dose of 25 mg/1
Cl2 effectively removed all of the virus seed in the SCSO
(7.7 logs of 0X174 and 3.7 logs polio-1), as did 12 mg/1 C102
(8 logs of 0X174 and 4.6 logs polio-1). If numbers 4 and 5
of Table 27 (see Figure 39) are compared with sample numbers
4 and 5 of Table 28, it is clear that the C1C>2 inactivated
most of the virus in the first 60 seconds, whereas Cl2
inactivation took longer. Twenty minutes after the addition
of creek water, samples 8 and 9 of Table 27, Cl2 had inacti-
vated all of the virus added, indicating that Cl2 residual
probably continued to have some viricidal action even after
dilution with creek water. No statement can be made concerning
the C102 residual since very few viruses survived the first
60 seconds of treatment (sample numbers 5 and 6 of Table 28).
100
-------
Unfortunately, the experiment required a large initial volume
of SCSO and high concentrations of polio-1 could not be at-
tained. It is possible that the 1:1 dilution performed after
treatment (i.e., dilution upon entrance into the stream - see
sample numbers 4, 5, 8 and 9 of Table 27) may have reduced
the polio-1 below detectable levels.
This illustrates one of the major problems in bench-scale
aftergrowth studies. If the low initial virus level has been
diluted by addition to the streams or lakes (1:28 total dilu-
tion in the case of Onondaga Lake), the question remains
whether the virus had been efficiently inactivated by the
disinfectant, or the dilution has simply put the virus below
conventional detection techniques.
Even at 25 mg/1 Cl2/ some virus may have reached the lake,
as indicated by the small titers of 0X174 picked up in the
20 and 60 minute samples (Table 27, sample numbers 8, 9, 12
and 13). No indication of virus getting to the lake was
seen in the 12 mg/1 C102 experiment.
Samples 10 and 14 of Table 27 and 28 indicated no viricidal
action by creek water, and sample 19 showed no viricidal
action by lake water. Therefore, one cannot depend on the
natural water into which CSO discharge for the inactivation
of any virus which has escaped disinfection.
Both disinfectants were effective at the levels used. The
Cl2 efficiency, however, was partly dependent upon residual
activity which occurred after entrance of the CSO into the
receiving water. This is probably less dependable than the
C102 treatment in which almost all of the virus was inacti-
vated before entrance into the stream. It is anticipated
that the use of the resistant f2 phage may give a more reli-
able index to the possible number of pathogenic viruses which
could possibly enter the lake.
Piscussion--
It can be concluded that aftergrowth may occur, but it is
difficult to assess this phenomena in a laboratory experiment.
It will also be difficult to determine aftergrowth on a full-
scale test in the demonstration phase because of the large
numbers of bacteria entering Onondaga Lake from untreated CSO,
and from the existing treatment plant. Research of this type
is bes.t conducted in rivers and streams where the bacterial
growth can be observed in a natural environment free from
interferences and other bacterial inputs.
101
-------
scso
SEEDED WITH VIRUS
#2
AFTER SCREENING
_T I 2 mg/l CI02 or
T 25 mg/l CI2
DILUTION WITH CREEK WATER
1:14 DILUTION WITH LAKE WATER
Figure 39. Key for samples collected in viral aftergrowth
study
102
-------
Table 27. Aftergrowth of Virus; Di'slnfected with C3-2
Sample Number
From Figure 39
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Table 28. Aftergrowth
Sample Number
From Figure 39
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Polio-1
(PFU/ml)
7.4 X 103
6.6 X 103
6.4 X 103
9.2 X 101
4.0 X 10°
— _ —
1.4 X 103
0.0
0.0
_ __
5.8 X 103
0.0
0.0
5.0 X 101
0.0
2.2 X IQl
0.0
0.0
4.0 X 10°
0.0
of Virus Disinfected with
Polio-1
(PFU/ml)
5.8 X 104
5.8 X 104
5.9 X 104
2.0 X 10°
3.2 X 101
0.0
2.7 X 104
0.0
0.0
0.0
1.8 X 104
0.0
0.0
0.0
0.0
1.0 X 103
0.0
0.0
1.2 X 101
0.0
0X174
(PFU/ml)
7.3 X 10/
8.6 X 107
7.9 X 107
6.0 X 105
5.0 X 104
__«
1.1 X 108
3.0 X 10°
3.0 X 10°
4.0 X 104
5.8 X 107
6.0 X 10°
3.0 X 10°
5.0 X 104
0.0
2.7 X 106
7.3 X 101
0.0
2.5 X 103
0.0
C102
0X174
(PFU/ml)
1.6 X 108
2.0 X 108
1.3 X 108
3.6 X 102
1.5 X 103
0.0
1.1 X 108
0.0
1.4 X 102
0.0
5.8 X 107
0.0
0.0
0.0
0.0
1.6 X 106
0.0
0.0
3.3 X 103
0.0
103
-------
Breakpoint Chlorination
The results for ammonia removal by breakpoint Chlorination
are given in Table 29.
Table 29. Breakpoint Chlorination in SCSO
Time (seconds)
C12 (mg/1)
0
5
20
30
35
40
45
50
60
Cl?:NH3Na
0
1:1
4:1
6:1
7:1
8:1
9:1
10:1
12:1
0
5.35
5.35
5.35
5.35
5.35
5.35
5.35
5.35
5.35
30
NH^N
5.35
5.35
4.87
3.51
1.68
1.08
0.79
0.50
0.37
120
(mg/1)
5.35
5.35
4.59
3.23
1.50
0.29
0.14
0.10
0.11
300
5.35
5.35
4.48
3.06
1.54
0.36
0.09
0.06
0.08
a mg/l:mg/l
The ORGN, T-ALK, pH and NC>3N, N02N values changed by less than
10% of the original values. The results support other experi-
ments^7 showing ammonia removal at C12:NH3N weight ratios
greater than 7.6:1 in wastewaters. In practice, the break-
point Chlorination may be difficult to carry out since strict
pH control at 6.8 + 0.5 is necessary. If the natural buffering
capacities of wastewaters is exceeded, pH adjustments are
necessary. Although this did not occur in these studies, this
possibility must be investigated for more dilute CSO. Failure
to maintain proper pH results in the substitution of one pro-
blem (NC13 or N03N) for the original (NHsN) as shown in the
procedures section.
The expense of a minimum 7-6:1 ratio excess of Cl2 to NH3N
must be evaluated in view of other means of ammonia removal.
The other common possible methods are biological nitrification,
stripping and ion exchange processes. The first of these
requires long detention times of several hours, and the second
is not practical in northern regions of the country for climatic
reasons and is not considered in this report. The use of
conventional synthetic ion exchange resin has been criticized
for its expense and lack of selectivity. However, the possi-
bility of using a naturally occurring material, clinoptilolite,
is presently being pursued under U.S. EPA Grant No. S-8024007"1
The final report on this project will present detailed costs
of this method.
104
-------
The operating costs of breakpoint chlorination, considering
only Cl2, is calculated as follows:
1. Laboratory Results:
8.5 mg Cl2/mg Nt^N is required to reach the breakpoint
in CSO
2. Assumptions:
Average maximum NH^N in CSO is 5 mg/1 (Appendix A).
Number of treatment stations on CSO system is 601-
Average station capacity is 15 mgd1-
Average duration of one CSO is 2.5 hr1.
Average number of overflow occurrences is 8.8/mol.
Cost of Cl2 is $0.10/lb (ton cylinder) ] 1974
Cost of Cl2 is $0.07/lb (liquid hypochlorite)} prices
3. Conversion Factors:
1 Ib = 454 gm
1 gal = 3.785 1
1 mg/1 = 8.34X10-6 Ib/gal
1 hr = 4.17X1Q-2 day
4. Calculations:
a. Ib of Cl2 required per gal CSO to reach breakpoint
(5 mg NH3N/1 CSO) X (8.5 mg Cl2/mg NH3N) =
(42.5 mg C12/1 CSO)
(42.5 mg C12/1 CSO) X (8.34X1CT6 lb/gal/mg/1) =
(3.54X10~4 Ib Cl2/gal CSO)
b. gal CSO to be treated in one year
(60 stations) X (1.5X107 gal CSO/day/station) X
(4.17X10"2 day/hr) X (2.5 hr/occurrence) =
(9.36 X107 gal CSO/occurrence)
(9.36 X 107 gal CSO/occurence) X (8.8 occurrence/mo)
X (12 mo/yr) = (9.88X109 gal CSO/yr)
c. Ib Cl2 required per year
(9.88X109 gal CSO/yr) X (3.54X10~4 Ib Cl2/gal
CSO) = (3.50X106 Cl2/yr)
105
-------
d. cost of Cl2 per year
ton cylinders
(3.50X106 Ib Cl2/yr) X ($0.10/lb) = $350,000/yr
liquid hypochlorite
(3.50X10^ Ib Cl2/yr) X ($0.07/lb) = $245,000/yr
Thus, for ammonia removal in CSO, the cost for Cl2 for one
year is $245,000 or about $0.025 per thousand gallons of
treated CSO. This compares with a cost of approximately
$135,000 for disinfection alone based on 25 mg/1 Cl2- For
two-stage disinfection with 8 mg/1 C102 and 2 mg/1 Cl2 / the
cost would be $45,000 plus the cost of C102. The additional
cost of ammon removal beyond the cost of disinfection is
$110,000 or about $0.01 per thousand gallons of CSO. This
cost compares very favorably with stripping which has been
estimated at $0.02 per thousand gallons. Other methods are
generally thought to have even higher costs.
DESCRIPTION AND OPERATION OF DEMONSTRATION FACILITIES
Introduction
The discussion of the results of the bench-scale studies indi-
cates that because of the difficulty in simulating field con-
ditions, particularly mixing, a complete assessment of the
factors affecting disinfection was not possible. Therefore,
the demonstration of full-scale facilities hereafter outlined
will address the following questions: 1) What degree of confi-
dence should be placed on the results from bench-scale disin-
fection studies when projecting the designing of full-scale
tankage and disinfectant-generating equipment? 2) What degree
of confidence can be placed on the selection of operating para-
meters such as disinfectant dosages by assessing bench-scale
results? 3) What can be considered a feasible method for
achieving a high-rate removal of microbial contamination? 4)
What is the effect of various levels of high-rate suspended
solids removal prior to high-rate disinfection?
To address each of these questions by subjecting the demonstra-
tion facilities to various modes of operation is the major
objective of the field program. This program will have a
major impact on the overall CSO abatement program for
Onondaga County and many of the results and observations will
have an impact on a national basis. This section describes
the demonstration facilities, their subsequent operation and
the relation of proposed evaluation to the results of the
laboratory studies. Also included in this section is a
description of the sampling and analysis program designed to
provide data with which the feasibility of process concepts
106
-------
will be assessed.
Description of Facilities
The site plan for each of the demonstration facilities is
shown in Figures 40 and 41 for Maltbie Street and West Newell
Street, respectively. The Maltbie Street facility was
designed around the concept of high-rate, fine-mesh screening
followed by high-rate disinfection. This station includes
several pieces of mechanical equipment and automated control
instrumentation. The West Newell Street facility was designed
around the swirl concentrator conceived in England by
Smisson^ , and further developed by the U. S. Environmental
Protection Agency in cooperation with the American Public
Works Association, General Electric and LaSalle Hydraulic
Laboratory, in Montreal, P.Q.73. The swirl flow regulator-
solids concentrator concept of first controlling or regula-
ting storm flow and simultaneously treating the flow was
installed to demonstrate the feasibility of an installation
relatively free of mechanical equipment.
The design of the facilities was initiated before the bench-
scale studies had been completed. Therefore, hydraulic and
process flexibility were maximized wherever possible in anti-
cipation of variations in process concepts that would be
precipitated by an analysis of the bench-scale results. Also
adding to the consideration of design flexibility were the
results of a literature search of the previously completed
CSO characterization programs which indicated a wide varia-
bility of microbial and organic discharges. This variability
was verified by a characterization program of three different
CSO within the Onondaga Lake drainage basin (Appendix A).
Maltbie Street Prototype Treatment Facility—
Pumping Station—As shown in Figure 40, the Maltbie Street
Pumping Station is located at the discharge of a CSO into
Onondaga Creek. Figure 42 illustrates that the pumping
station structure is divided into three compartments, namely,
the influent chamber, the metering chamber and the wet well.
The chamber is equipped with a bar screen and an emergency
bypass to provide the removal of large particulates and
allow the bypassing of the total CSO in the event of pump
failure.
The metering chamber was designed with a magnetic flow meter
(Brooks Instrument Division, Emerson Electric Company, Hatfield,
Pa.) which will measure the total CSO emanating from the over-
flow regulator. Maximum capacity of the existing outfall has
107
-------
ONONDAGA
CREEK
DISINFECTION CONTACT
TANKS
O
OO
TOTAL DISINFECTED
EFFLUENT
OVERFLOW REGULATOR
W/ LEAPING WEIR
TRANSPORT
TRUNK
SOLIDS CONCENTRATE -
LINE
SIPHON TO MAIN-
INTERCEPTOR
Figure 40. Maltbie Street site plan
-------
EXISTING COMBINED SEWER
*= SAMPLING POINT
~v
\
\
( H
\ i i
\ i
\\ ' /
\ \ SOLIDS i /
\ \ CONCENTRATE ' '
\ \UNE 1
> ' II COMBINED
\ \ ' 1 SEWER
! . , || INFLUENT
\ \ ' '
I ' '
\\ ,
\\
\\ '
U 1
PUMP (g) / |
MANHOLEVr^/ I .
»1 II
MAGMETER— ^^f j |
MAW
; i
fit:
i
SOLE ' ' '1
\ \ » 1 i y
\\> < | |
— ~J //'*~~~**\\\l DISIN-
-J (( <~>&\\ I CI2 or FECTICN
\ U ^ ) Cl°2 EOUIP-
\ \V_^X7 / MENT
< V^ x X HOUSING
SWIRL "V'
CONCENTRATOR
Figure 41. West Newell Street site plan
109
-------
AIR FLOATATION CELL
*rSOLIDS CONCENTRATE LINE
SWECO
WASTE-
WATER
CONCENT-
RATOR
CRANE
"MICRO-
STRAINER"
SCREENING BUILDING AND DISINFECTION TANKS
KEY
M - FLOW METER
X - SAMPLING LOCATION
---FLOW DIRECTION
'-I—L^ —
x
o I
o
PUMPING STATION
figure 42. Maltbie Street process orientation
-------
been calculated as 30 mgd (1314 I/sec.). The flow signal
from the magnetic flowmeter will be used to activate a circuit
to which all sampling equipment will be wired.
The third chamber in the pumping station acts as a wet well
for the overall pumping system which is located above the
chamber. The pumping system was designed as three parallel
pumping systems each consisting of a 2.5 mgd (109.5 I/sec.)
constant speed and a 2.5 mgd (109.5 I/sec.) variable speed
pump. The three 5 mgd (219 I/sec.) pump combinations serve
to feed three parallel high-rate screening and disinfection
systems. These systems are described later in this section.
The pumping systems will provide a variable or constant flow
to the screening units. Under variable flow operation, the
variable speed pump will be activated by a level sensor in
the wet well. It will operate until its capacity of 2.5 mgd
(109.5 I/sec.) is reached at which time the constant speed
pump will be activated. The variable speed pump will continue
to operate until the 5 mgd (219 I/sec.) capacity of the single
pumping system is reached. To provide an operation under
constant flow conditions, the variable speed pump will be
manually inactivated, and upon the occurrence of an overflow,
the constant speed pump will automatically start when the wet
well level is sensed.
Located on the discharge side of each pumping system is a
magnetic flowmeter which will provide a signal to activate
a screening unit and the disinfection equipment associated
with that screening unit. These flow signals will permit
unattended operation of the entire facility, thereby decreas-
ing manpower requirements and overall operating costs. This
factor will be taken into consideration in the evaluation of
the facility.
Screening Capabilities—The screening facilities illustrated
in Figure 42 were hydraulically designed to provide flexibility
in modifying treatment processes. All influent and effluent
piping is of steel fabrication which will simplify any modi-
fications in the piping arrangement. Modifications will be
made during the demonstration program if results indicate
that a change or changes may optimize the high-rate process.
The parallel screening units consist of a Crane Microstrainer
(Crane Co.,' Chicago, Illinois) with a screen aperture of 23
microns (Mark O), a Zurn Micro-Matic ® (Zurn Industries, Inc.,
Erie, Pa.) with a screen aperture of 71 microns and a Sweco
Wastewater Concentrator ® (Southwestern Engineering Co.,
Massilon, Ohio) with a screen aperture of 105 microns. The
111
-------
specific screening units were selected on the basis of
results obtained from previous high-rate operation of the
screens41'74'75 and the variability in process design
afforded by these units.
The Crane and Zurn units are alike in that both remove solids
through a finely-screened drum which rotates relatively
slowly (4.5 to 6.5 rpm) around an horizontal axis. The Crane
unit has had the higher number of operating hours on CSO
between the two units; however, it is expected that each will
provide similar suspended solids removal capabilities. The
Sweco Wastewater Concentrator removes TSS by the use of a
combination of finely-meshed screens fastened to a cage which
revolves at a high speed (55 rpm) around a vertical axis.
The concentrator is followed by an air flotation cell which
takes advantage of entrapped air in the screened effluent for
a higher degree of suspended solids removal.
Initially, the loading rates on the screening units will be
varied throughout the duration of the overflow by operating
each pumping system in the variable state. The loading rates
on the Zurn and Crane units may vary from approximately 10 to
45 gpm/ft2 (0.41 to 1.84 1/min/m2) during any given runoff
period. Because of the larger screen aperture on the Sweco
unit, the loading rates on it may vary from approximately 30
to 45 gpm/ft2 (1.23 to 1.84 1/min/m2). Some evaluation of
the range of loading rates at which each unit can effectively
operate will be attempted along with an assessment of the
operational efficiency of the units under varying hydraulic
conditions.
In order to better evaluate the operating range of each unit,
however, the flow to the units will be held constant during
several trials to provide loading rates of 30 to 45 gpm/ft2
(1.23 to 1.84 1/min/m2) on the Crane and Zurn units and
loading rates of 85 to 145 gpm/ft2 (3.48 to 5.94 1/min/m2)
on the Sweco unit. This assessment of operating ranges will
hopefully provide enough information from which to project
the necessary number of screening units, and thus tl\e
building size for various point-source treatment facilities.
Each screening unit will be evaluated for its operating effi-
ciency and degree of maintenance. Data will be accumulated
on the ability of the screening units to start and stop after
both long and short periods in and out of operation, on the
effectiveness of their backwash cycles, and on the durability
of the screening material by assessing screen life.
Aside from the operating efficiencies of each unit, the efflu-
ent TSS quality from each screen will be evaluated as to its
112
-------
effect on the disinfection process. No conclusive findings
could be made during the bench-scale studies regarding this
phenomena due to the difficulty in simulating a screening
process in the laboratory. Therefore, since each screening
unit is equipped with screens of different aperture sizes
and it is anticipated that the effluent emanating from each
will differ in TSS quality, the effect of aperture size on
the disinfection process can be further evaluated.
During the demonstration period, the screens on two of the
screening units will be changed to produce different quality
effluents. The aperture size selected will be dependent upon
the results of the initial evaluations outlined above. How-
ever, the physical size and shape of the TSS may be different
due to the different methods of removal provided by the Sweco
Wastewater Concentrator and the Crane and Zurn microscreens.
An hypothesis formed from the results of the bench-scale
studies purports that the method of TSS removal may have an
effect on the bactericidal and viricidal efficiency of the
disinfecting agent. The reliability of this hypothesis will
be evaluated through the results obtained during the demonstra-
tion program.
Throughout the entire period of demonstration, the total
amount of TSS removed will be assessed as to its effect on
interceptor sewer loadings, assuming all the collected TSS
are returned to the main intercepting sewer. Also projected
will be the effects of these TSS on the treatment and TSS
handling capacity at the local sewage treatment plant. These
evaluations will have to be made in order to project the
requirement of on-site solids handling at each point-source
treatment facility.
Disinfection--As noted above, various evaluations will be
made on the effects of solids on the disinfection process.
The disinfection facilities available for the demonstration
project were designed to provide high-rate inactivation of
bacteria and viruses. The levels to which the bacteria
must be reduced in order for the disinfection process to be
judged sufficient is discussed earlier in Section V. It
should be noted that the standard of 1,000 TC per 100 ml is
a maximum level to be measured in the receiving waters for
this demonstration, but the standard will be used as a goal
for bacterial quality in the effluent.
The disinfection detention facilities consist of three
parallel tanks, one for each of the effluents from the para-
llel screening processes. The tanks were sized by using the
113
-------
one-minute contact period that was indicated as sufficient
for reaching the bacterial standard from the results of the
bench-scale tests. Each tank was designed with a proportional
weir which will provide a constant velocity and, therefore,
a constant detention time regardless of flow. This constant
contact period will facilitate trial-to-trial comparisons of
disinfection techniques despite variability of flow rates.
In order to demonstrate the effectiveness of different mixing
applications, a common header to each tank from a single
screening unit is now being proposed. This will insure that
the influent to each tank will be as equal as possible, thus
maximizing the validity of any comparison of mixing procedures.
Initially, two tanks will be equipped with three flash mixers,
one located at the point of disinfectant injection and the
others located near the downstream end of each longitudinal
baffle. The third tank will be equipped with a single flash
mixer at the point of disinfectant injection. This tank will
be available for the installation of Glover's corrugated
labyrinth design (discussed below). This demonstration study
will include single-flash mixing in each tank and sequential-
flash mixing.
Bench-scale studies used complete mixing in a way that may
not be duplicated in a full-scale facility. Therefore, a
portion of the project will be devoted to demonstrating the
influence that various techniques of mixing have on the dis-
infection process. The detention tanks were designed to allow
the addition of several types of facilities for this purpose.
Those that have been selected for demonstration include flash
mixing, sequential-flash mixing, and increased turbulence
through the use of corrugated labyrinths. Each of these
mixing techniques will be assessed against a no-mix condition.
Single-flash mixing will provide for a nearly instantaneous
mixing of the disinfectant and the CSO at the point of appli-
cation. The effect on disinfection efficiency of this
technique will be compared with that of sequential-flash
mixing. During the laboratory studies, two-stage disinfection
was performed to determine whether or not sequential mixing
should be considered as a demonstration possibility. Although
the results were far from conclusive, they indicated that
this concept warranted consideration during the demonstration
program. Positive results were observed by Kruse, et.al.,45
during a full-scale sewage treatment plant study of sequen-
tial-flash mixing, and by Dow Chemical39 during a high velo-
city, narrow flow-through tube study.
114
-------
Pilot work by Glover42 indicated that an increase in
turbulance throughout the length of the detention tank will
increase the efficiency of the disinfection process. The
design objective for Glover's high-rate pilot contact chamber
was to achieve a G't factor of 10,000; G1 being the velocity
gradient and t being the detention time in the tank. Since
detention time is relatively constant the only manner in
which G't can be increased is by increasing G'. Glover did
this by inserting corrugated, closely-spaced baffles parallel
to the flow. A similar installation will be made in one of
the parallel demonstration tanks to compare the efficiency
of this disinfection technique to the others listed above.
In addition to assessing the physical mechanics of disinfec-
tion, the type of disinfection (single- or two-stage) and the
optimum dosage quantities of Cl2 and/or C1C>2 will be assessed.
The bench-scale studies evaluated the optimum dosages, here-
after referred to as minimum dosages which reduce the bacter-
ial levels below the defined goals, of Cl2 and C102 on a
single-stage basis and also the optimum combination of Cl2
and C102 dosages on a two-stage basis. The results and a
subsequent discussion of these studies are presented in
Section V. The bench-scale studies concluded that single-
stage Cl2 and ClC>2 disinfection will be optimal at 25 and
12 mg/1, respectively, and that two-stage disinfection with
Cl2 followed by C102 will be optimal at 8 and 2 mg/1,
respectively (it should be noted here that these dosages are
all based on contact periods of two minutes or less). It
was also concluded that two-stage disinfection will produce
an effluent of acceptable bacterial quality at a lower cost
than single-stage will produce.
The one major drawback in projecting laboratory results to
full-scale application is the inability to simulate actual
field conditions in the laboratory. Anticipated conditions
such as temperature fluctuations and TSS variability were
studied and accounted for when analyzing the results.
However, it was impossible to simulate the various physical
shapes of solid particles that may exist in the effluents
of different solid removal processes. Simulation of the
incomplete mixing process in the contact tanks was also very
difficult. Therefore, the bench-scale results for both
single-stage and two-stage disinfection must be verified by
full-scale testing.
As stated above, the disinfectant agents that will be com-
pared or combined sequentially will be Cl2 and C102. These
agents, however, will be generated in a different manner in
the demonstration program than they were in the bench-scale
115
-------
tests. The C3-2 used in the laboratory was obtained as a 5%
solution of sodium hypochlorite (Section IV), whereas_C12
will be generated at the demonstration site by combining Cl2
gas stored in ton cylinders with water to form liquid HOC1.
The C102 used in the laboratory was generated according to the
technique described in Standard Methods5, whereas C102 will
be generated by means of a Nitrosyl Chloride generation
system (U. S. Patent 375079)6 at the demonstration site.
Particular attention will be given to the C1C>2 generation
method since it is a new process for full-scale application
and the concentration of C1C>2 produced is critical. The pro-
cess consists of pumping two chemicals, a NaCl03-NaNC>2 (sodium
chlorate-sodium nitrite) slurry and HNC>3 (nitric acid) , which
will mix in a specially designed lucite reaction chamber.
The resulting reaction is expected to produce a 12 percent
solution of C102 that will be fed directly to the disinfection
contact tank. The product will be sampled as often as possible
to determine the consistency of C102 concentration.
The capacity of each generator was selected on the basis of
the generation of an amount of disinfectant sufficient for
treating a 5 mgd (219 I/sec.) flow (maximum capacity of one
contact tank) at the dosages that were determined as optimum
from the bench-scale results. However, with the hydraulic
flexibility of both the pumping system and the screening units,
it will be possible to decrease total flow, increase screen
loading capacity (decrease drum submergence) and thus, increase
the dosage rate of Cl2 and/or C1C>2.
Sampling and Analytical Program—Aside from influencing the
design and operation of the demonstration treatment facilities
and related instrumentation, the results of the bench-scale
tests will also have an effect on the type and amount of
sampling and analysis that will be performed during the demon-
stration program. Table 30 presents a tentative outline for
the operation of the Maltbie Street facility. The various
hydraulic and process alternatives that will be demonstrated
have been discussed in the previous sections describing this
facility. For each trial, samples will be taken at the influ-
ent to the screening units, the effluent to the units and the
flotation cell, and at key locations in the disinfection
contact tanks. These locations will be selected on the basis
of the mixing application used in the particular tank. For
single-flash mixing and Glover's corrugated baffle system,
the samples will be collected immediately after the mixer,
midway, and at the end of the tank. For sequential-flash'
mixing, the samples will be collected after each mixer and at
the end of the tank. The data is to be evaluated as follows:
116
-------
Overflows Single-stage C102 disinfection verification and
(1-3) the effect of various amounts of TSS on disinfec-
tion. Preliminary evaluation of various screen
loading rates.
Overflows Single-stage Cl2 disinfection verification and
(4-6) comparison of TSS effect (C102 vs. Cl2). Increase
data on screen loading rates.
Overflows Intense evaluation of high screen-loading rates.
(7-10) Attempt to assess validity of hypothesis on effect
of physical shape of solid particle on disinfection.
Overflows Two-stage disinfection verification and comparison
(11-14) of single- and two-stage in parallel tanks with
near equal influent suspended solids.
Overflows Using optimum method of disinfection, evaluation of
(15-20) mixing techniques.
The samplers to be used are Sigmamotor refrigerated, sequen-
tial samplers (Sigmamotor, Inc., Middleport, N.Y.). As
previously stated, they will be activated when a flow is
sensed in the 30-inch flowmeter located in the pumping station,
The sampling interval will initially be set at 15 minutes
which will allow for a high accumulation of data throughout
the critical period of operation (first flush). Therefore,
if the CSO extends over a six-hour period, there will be a
possibility of collecting 24 samples at each location. An
analytical schedule is presented in Table 31.
West Newell Street Prototype Treatment Facility—
Swirl Concentrator—Figure 41 illustrates the relationship
of the swirl concentrator to the existing service trunk sewer
and combined sewer overflow located at West Newell Street.
The background and experimental work completed on the swirl
concentrator is documented in U.S. EPA reports73"76. The
design adopted for this installation closely follows the
recommendations cited in the first report. A pump was added
to the solids concentrate line in order to allow the unit to
operate under forced as well as gravity conditions. Due to
existing hydraulic conditions in the interceptor system, the
pump is needed to maintain dry-weather flow in the primary
gutter. During a rainfall, the pump will shut off when the
flow through the swirl chamber reaches the calculated capacity
of the interceptor. The chamber will then fill to the weir
level and begin to overflow. As opposed to the Maltbie Street
facility, the swirl concentrator operates with relatively
117
-------
Table 30. Maltbie Street Operation Schedule
Screen Loading
Over- Rate (gpm/ft2)
flow
1
2
3
4
5
6
7
8
9
10
11
, 12
13
14
15
16
17
18
19
20
c -
v -
F -
FS -
G -
Sweco Crane
V
V
V
V
V
V
73
73
73
73
c
c
c
c
c
c
c
c
c
c
Constant
variable
V
V
V
V
V
V
30
30
45
45
c
c
c
c
c
c
c
c
c
c
Single-flash
Screen Aperture
Size (microns) Cl2 Dosage (mg/1)
Zurn Sweco Crane Zurn Tank #1 Tank #2 Tank #3
V
V
V
V
V
V
30
30
45
45
c
c
c
c
c
c
c
c
c
c
mix
Sequential- flash
Glover1 s
con
rucrat
105
105
no scr.
105
105
105
105
105
105
105
common
H
11
"
11
"
"
11
11
"
mix
:ed labvri
23
23
23
23
23
23
23
23
23
23
71
71
71
71
71
no scr.
71
71
71
71
header
ii
"
11
11
11
11
11
"
"
.nth
t
1
1
I
0
0
0
25
25 +
25 +
25 +
0
25 +
0~
0
0
0
0
8+
8 +
8 +
8 +
8+
8 +
0
0
0
25
25+
25+
25+
0~
25 +
0
25+
25 +
25+
25 +
8+
8+
8+
8 +
8+
8 +
0
0
0
25
25+
25+
25+
0
25+
0~
8
8+
8+
8 +
8+
8 +
8+
8+
8+
8+
+ - Vary dosage up or down
NM - No mix
118
-------
Table 30. Maltbie Street Operation Schedule (Cont'd)
C102 Dosage (mg/1)
Tank #1Tank #2Tank #3
12 12 12
12+ 12+ 12+
12+ 12+ 12+
000
000
000
000
12+ 12+ 12+
000
12+ 12+ 12+
12+ 0 2
12+ 0 2+
12+ 0 2+
12+ 0 2+
2+ 2+ 2+
2+ 2+ 2 +
2+ 2+ 2+
2+ 2+ 2+
2+ 2+ 2+
2+ 2+ 2+
c - Constant
v - Variable
F - Single-flash mix
FS - Sequential-flash mix
G - Glover's currugated labyrinth
+ - Vary dosage up or down
NM - No mix
Mixing
Tank #1
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
NM
F+
F+
F+
F+
Tank #2
F-
F
F
F
F
F
F
F
F
F
F
F
F
F
NM
G
G+
G+
G+
G+
Tank #3
F
F
F
F
F
F
F
F
F
F
F
F
F
F
FS
FS
FS +
FS+
FS+
FS +
Cost
(dollars)
9,000
9,000
9,000
9,000
4,000
4,500
4,500
4,500
4,500
4,500
4,500
4,500
4,500
4,500
4,500
4,500
6,750
6,750
6,750
6,750
119
-------
Table 31. Maltbie Street Analytical Schedule
Total
Screen
Parameters Influent
BODs
TOC
COD
TKN
NH3N
N02N
N03N
T-IP
Cl
T-Alk
TSS
Sett. Solids
VSS
TSa
vsa
TC
FC
FS
PH
Oil & Grease"
Metalsc
Flowrate
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Samples
Each
Screen
Effluent
X
X
X
X
X
X
X
X
X
X
X
X
X
X
to be taken
Flotation
Effluent
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Disinfec-
tion Tank
Locations
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
5* Analyses on composites or every six samj:
Analyses on selected composites
c Includes Hg, Pb, Cr, Fe, Cu, Cd, Ni, Zn
little mechanical equipment, thus providing a marked contrast
in anticipated operating and maintenance expenses.
The influent to the unit is comprised of the entire flow (dry
and wet-weather) from the service trunk sewer. This flow
averages approximately 1.0 mgd (43.8 I/sec.) during dry-
weather conditions and ranges from an average of 3 mgd (131.4
I/sec.) to a maximum of 8.9 mgd (398.8 I/sec.) during wet-
weather conditions.
Under complete gravity service, dry-weather conditions will
produce a flow which will be kept within a channel located in
the floor of the swirl unit. The flow will be discharged
through the solids concentrate line which will carry the flow
back to the interceptor. During wet-weather or runoff
120
-------
conditions, the flow in the dry-weather channel will increase
until it spills out onto the floor of the swirl chamber.
The water level in the tank will then continue to rise to
the level where it will spill over the overflow weir and
discharge to the receiving stream.
A swirling action will be produced by the momentum of the
influent flow and the geometry of the tank during an overflow
condition. This swirling pattern will cause the solid
particles suspended in the flow to move toward the outside
portion of the tank and downward. Many of these particles
will then become trapped in the dry-weather channel and
subsequently will be removed through the solids concentrate
line.
The pump that has been installed in the solids concentrate
line will provide the flexibility of testing the operation of
the swirl concentrator under both gravity and pumping condi-
tions. It is anticipated that the swirl concentrator may
not be feasible in many locations in Onondaga County as well
as nationwide due to the lack of available hydraulic head to
direct the dry-weather flow back into the main sewer line.
Although pumping will increase operating and maintenance
costs, it may be necessary to overcome hydraulic restrictions.
Disinfection—The portion of the flow which will spill over
the weir will be disinfected with ClC>2 generated in the same
manner as outlined for the Maltbie Street facility. There
is no specially designed disinfection contact chamber follow-
ing the swirl concentrator, only a 30-second to one-minute
detention time in the effluent piping. A flash mixer will
be available at the point of the C1C>2 injection to enhance
the probability of ClC>2/microorganism contact. There are
also provisions to prechlorinate and take advantage of the
mixing action inherent in the swirl chamber.
During the initial operation of the facility, an Englehard
Chloropac sodium hypochlorite generating system^ (Englehard
Industries Division, Englehard Minerals and Chemicals
Corporation, East Newark, N.J.) will be installed and will
be available for demonstration toward the middle of the demon-
stration period. The system will utilize an existing brine
supply as its influent, and through the use of Englehard's
electrolytic process, sodium hypochlorite will be generated,
stored on site, and fed to the swirl concentrator effluent
during wet-weather conditions.
By installing the Englehard system at West Newell Street, an
evaluation of the use of sodium hypochlorite in the two-stage
121
-------
disinfection process will be possible. It will also provide
an opportunity for assessing the comparative reliability of
C102 and sodium hypochlorite generation techniques.
A summary of the intended operational schedule is given in
Table 32.
Table 32. West Newell Street Operation Schedule _
Disinfection Englehard
_
C102 (mg/1) C102 (mg/1) Cl2 (mg/1) C102
Storm Flow Pre-disin- Post-disin- Pre-chlori- Post-chlori
No. Rate fection fection nation nation
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
V
V
V
V
V
V 15+
V 15+
V 15 +
V 15 +
V 15 +
V 15+
V
V
V
V
V
V
V
V
V
V
12+
12 +
12 +
12 +
12 +
2 +
2 +
2+
4 +
4 +
4 +
4 +
8 +
8+
8 +
8+
8 +
8+
8 +
25+
25 +
25 +
20+
20+
20+
+_ - Vary flow up or down
Sampling and Analytical Program—The sampling equipment,
sampling intervals and analytical parameters for West Newell
Street are ^listed in Table 33. They are similar to those
outlined for Maltbie Street in Table 31. The samples will be
collected from the influent, the effluent prior to disinfec-
tion, and the effluent before it is discharged to Onondaga
Creek. Samples will also be collected from the C1O2 and
sodium hypochlorite generators on a random basis to monitor
the strength of the disinfectants and the consistency of the
generation process. The removal of TSS by the swirl concen-
122
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trator is a function of the settling properties of the
particles as well as other parameters. Therefore, the
settling velocities of the TSS in the West Newell Street
overflow will be measured for several storms. Periodic grab
samples will be taken at all locations to check on the
reliability of the Sigmamotor automatic samplers. Particular
carewill be taken to verify the TSS removals.
Table 33. West Newell Street Analytical Schedule
Samples to be taken
Parameters Influent
Pre-Disinfected
Effluent
Post-Disinfected
Effluent
BOD5a
TOC
COD
TKN
NH3N
NO 2
NO 3
T-IP
Cl
T-ALK
TSS
Sett. Solids
VSS
TSa
TVSa
TC
FC
FS
PH
Oil & Grease^
Metals0
Flowrate
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
a Analyses on composite of every six samples
k Analyses on selected composites
c Includes Hg, Pb, Cr, Fe, Cu, Cd, Ni, Zn
Special Instrumentation
The flow data that will be generated will be telemetered to
a central location, identified and stored on punch tape. The
tapes will then be processed and the information premanently
stored, along with coinciding analytical and rainfall data,
on computer disc files. The purpose of the telemetry and
computer system is to minimize man-hours in data handling
and to establish a basis for a central control station for
123
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the overall CSO abatement program.
Also included in the demonstration program will be an evalua-
tion of the reliability of the Badger Meter Suspended Solids
Monitor (Badger Meter Company, Milwaukee, Wis.). This
monitor is based upon an optical depolarization method which
was developed earlier by American Standard80. Badger Meter
has carried on further development of the solids meter,
refining its optical and electronic design and adapting the
meter for unattended service in a sewer environment.
The meter will be installed in several flow streams at both
Maltbie Street and West Newell Street. It will be tested
under various suspended solids conditions starting with a
low concentration of less than 5 mg/1 and ranging up to
10,000 mg/1. Initial correlations will be made between meter
readings and laboratory measurements on specially collected
samples.
All chemical and operation data collected over the entire
period of demonstration at both Maltbie and West Newell
Street will be assessed from a standpoint of individual
process reliability and efficiency as well as overall CSO
treatment capabilities. This latter assessment will be made
by making use of the U.S. EPA Stormwater Management Model,
EPA Project No. 11024 DOC81"84 to project the feasible
alternatives for alleviating the CSO problem that exists in
Onondaga County. The information generated from this demon-
stration will also assist in the planning and implementation
of abatement programs throughout the nation.
124
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SECTION VI
SUMMARY
In order to prevent bacterial and viral contamination of
Onondaga Lake, it was determined that in addition to new
tertiary treatment facilities for municipal and industrial
discharges, combined sewer overflows (CSO) would have to be
treated. Various methods of transmission and centralized
treatment of these CSO were found to be relatively expensive^,
therefore, point-source treatment is to be investigated
through U.S. Environmental Protection Agency demonstration
grant, EPA No. S-802400 (11020 HFR) awarded to the County of
Onondaga. The treatment is to consist of different methods
of suspended solids removal followed by disinfection with
chlorine (Cl2) and chlorine dioxide (C102), either separately
or in various combinations. The contact times for disinfec-
tion of CSO are generally less than two minutes because of
the short distances and rapid flows from the point of disin-
fectant application to the point of CSO discharge. These
constraints are a result of geographic and economic limita-
tions that are imposed by the occurrence of CSO in highly
developed urban areas. In order to obtain approximate
dosages for field demonstration, it was necessary first to
perform high-rate disinfection utilizing a two-minute contact
time in the laboratory. Total coliform (TC), fecal coliform
(FC) and fecal streptococci '(FS) bacteria and polio-1,
Coxsackie B-3, ECHO-7, HSV-L2, NDV, YFV, Vaccinia, f2 and
0X174 viruses (see Table 6) were the indicator organisms used
to assess disinfection efficiency- In addition to bacterial
and viral indicators, adenosine triphosphate (ATP) was also
evaluated as an indicator of efficiency of disinfection and
as a measure of microbial population. In order to minimize
the sample-to-sample variations, a simulated combined sewer
overflow (SCSO) which consisted of 50 percent municipal
sewage and 50 percent distilled water was used for all bench-
scale studies.
The properties of C102 and its reactions in SCSO were deter-
mined using electron spin resonance (esr). In general,
results showed that in two minutes C102 reacts with various
substances in SCSO to yield chlorite ion (C102~). These
results were further supported by the DPD colorimetric
method8 which showed the sum of C102~ and C102 to be constant
in each sample to which C1O2 was added.
125
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The membrane filter (MF) technique for bacterial enumeration
was utilized after it was determined that heavy metals, chlori-
nated hydrocarbon pesticides, and suspended solids, in the
levels normally found in CSO, caused no significant difference
from TC levels measured by the MPN technique. The suspended
solids present in SCSO were shown to have a protective effect
on the bacteria so that counts were not representative of the
true bacterial populations. Therefore, tests were conducted
to determine the time for which a sample of SCSO should be
blended to give more representative bacterial counts. Sonica-
tion was disregarded as a method of solids dispersion because
previous studies20'21 showed that bacterial kills result from
the high frequencies employed in the procedure. Using a con-
ventional household blender, Hamilton Beach Model 50, a
blending time of six seconds yielded the maximum numbers of
TC, FC and FS.
An attempt was made to evaluate the effects of temperature and
mixing on the disinfection process. Raising the temperature
from 2°C to 30°C resulted in only a slight increase in high-
rate disinfection of bacteria with Cl2 and C1C>2 in SCSO. Other
studies in no-demand situations showed marked temperature
a o a *3
ef f ectsD/:'" . The difference may be due to the rapid competi-
tive reactions with disinfectant demands which are not pre-
sent in no-demand solutions. The results of temperature vari-
ation on high-rate disinfection of viruses in SCSO with C102
showed a 40 percent reduction in disinfection efficiency from
22°C to 2°C, but no change was observed at temperatures higher
than 22°C. This is most likely due to the fact that the con-
version of C102 to C102~ is more temperature dependent than
disinfection with C102. Other tests with C102, conducted with
0X174, showed only a slight increase in disinfection efficiency
between 2°C and 45°C. No temperature studies were conducted
for disinfection of viruses with Cl?/ since this subject is
well documented in previous studies^3. A greater degree of
mixing was accomplished in the bench-scale studies than is
normally obtained in full-scale operations. Since it would
have been difficult to measure the degree of mixing, rapid
and complete mixing was performed for all studies.
Since the removal of suspended solids will precede disinfec-
tion in the demonstration of full-scale prototype treatment
facilities, the effect of solids removal was evaluated in the
bench-scale studies. The results of disinfection studies
performed on samples that had been pre-screened through a 23
micron aperture were compared with similar studies on unscreened
samples. Although total suspended solids were reduced 60
percent with a 23 micron screen, only slight reductions in
BOD5 (4 percent) and bacteria (20 percent) were observed. In
126
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some cases the bacterial counts (unblended) in screened
samples were greater than in unscreened samples as has been
observed by other workers42> Possible reasons for increased
bacterial counts upon screening are the removal of natural
bacterial predators, the dispersion of clumps of bacteria
and increased bacterial growth rate due to the dispersion of
solids. Thus, in addition to the physical removal of bacteria
and solids, screening may affect the efficiency of disinfec-
tion in two opposing ways:
1. an increased exposure of bacteria that facilitates
rapid disinfection, and
2. an increased exposure of disinfectant-demanding
substances, that accelerates the reactions with
these substances.
On the basis of target levels of 1000 TC per 100 ml, 200 FC
per 100 ml and 200 FS per 100 ml, and target reductions of
five logs of viruses, tests were conducted to determine the
disinfectant dosages required to achieve satisfactory high-
rate disinfection. To reach the target levels of TC, a
dosage of 20 mg/1 Cl2 was required in 50 percent of the trials,
and little improvement was obtained with dosages of 25 mg/1.
A dosage of 25 mg/1 Cl2 was necessary to reach the desired
value of FS within two minutes in 25 percent of the trials.
It was found that the variations observed in duplicate trials
were of the same magnitude as the difference between screened
and unscreened trials. Thus, the effect of screening on high-
rate disinfection was considered negligible. Reductions on
the order of three logs of 0X174 virus were obtained in high-
rate disinfection of SCSO with 25 mg/1 Cl2- In general, both
bacterial and viral disinfection curves were biphasic as a
result of the disappearance of free Cl2 and subsequent forma-
tion of less potent combined Cl2/ primarily chloramines. The
target five log reduction of viruses was not reached with con-
centrations of Cl2 as high as 20 mg/1. Other work has shown
that viruses are not completely inactivated without achieving
breakpoint chlorination, in which the Cl2 demand is satisfied
to the extent that a free Cl2 residual can be maintained.
Dosages of 8 mg/1 and 16 mg/1 of C102 yielded target levels
of TC in 50 percent and 75 percent of the trials, respectively.
Similar results were obtained using FS, while a dosage of
4 mg/1 of C102 achieved target reductions in virus levels.
Viruses and bacteria showed considerable variability in sensi-
tivity to the C1O2 in the following order: polio-1, FS, TC and
0X174. Single-stage disinfection of bacteria and viruses with
C102 showed a rapid decrease in C102 concentration in SCSO,
127
-------
with the major disinfection activity completed within 120
seconds. Although screening had little effect on disinfec-
tion with Cl2, disinfection with C1C>2 was slightly improved.
On the basis of comparative tests, it was surmised that much
of the C102 demand is due to dissolved organics, which are
not so encapsulated within the suspended solids as the Cl2
demanding substances. Thus, screening does less to affect
C102 demand than Cl2 demand, but does expose more bacteria,
thus enhancing C102 disinfection efficiency. This was further
verified by an experiment in which suspended solids removal
by settling reduced Cl2 demand, but did not significantly
reduce CIO2 demand.
It was determined that C102 is preferred to Cl2 for high-rate
disinfection of viruses because C102 is effective over more
of the pH and temperature ranges normally found in CSO. C102
has shown viricidal activity toward representative species of
the major groups of animal and bacterial viruses. Slight
increases in disinfection of viruses were observed when ap-
plying C102 in stages, however, this was felt to be the result
of mixing phenomena. The application of Cl2 followed by C102
after a period of 15 or 30 seconds showed significant increases
in bacterial and viral reductions over the additive reductions
from comparable single-stage tests. The application of C102,
followed by Cl2 after 15 or 30 seconds, was performed using
only virus as an indicator and showed less significant increa-
ses. Since the demand substances have been shown to be dif-
ferent for Cl2 than for C102, the enhanced disinfection when
these materials were used in combination was not due to a
reduction in demand but rather an interaction between the two
disinfectants. It was surmised that upon the oxidation of
C102 to C102~ in SCSO, free Cl2 reduced the C102~ back to CK>2,
thus prolonging the existence of the more potent disinfectant,
C102- Such a process is particularly feasible in high-rate
disinfection in which free Cl2 is available for regeneration
of C102- In order to achieve target levels for TC, FC and FS
bacteria and target log reduction of viruses, a concentration
of 8 mg/1 Cl2 followed by 2 mg/1 C102 in 30 seconds was the
minimum effective combination.
Concurrent measurements of ATP, bacteria and viruses in CSO
and SCSO indicated the feasibility of using ATP as a reliable
and rapid method to control the disinfection process and as a
parameter of interest. On untreated CSO the linear correlation
of ATP with the indicator bacteria TC and FC gave coefficients
of 0.03 and 0.04, respectively. On disinfected SCSO similar
correlations gave 0.70 and 0.76 including all samples. At low
ATP (^1 arbitrary unit) and bacteria (a-1000 TC/100 ml) levels,
the coefficients were 0.84 and 0.79 for TC and FC, respectively.
At high levels (ATP -\,25 arbitrary units, TC 0,1000,000 counts/
100 ml) the coefficients were 0.21 and 0.51, respectively.
128
-------
results and trends are to be expected since ATP is a measure
of all organisms, and the numbers and diversity of organisms
is greatest in untreated samples. As the level of disinfec-
tion increases, the diversity of organisms decreases because
each species has a different susceptibility to disinfection.
Since the indicator bacteria are chosen as such because they
are among the most resistant fecal organisms, their predomi-
nance increases with the level of disinfection. Therefore,
at the low bacterial levels required for discharge of CSO,
ATP should be an acceptable indicator of fecal contamination.
The results showed that an ATP level could be chosen such
that all samples which had higher ATP values had bacterial
counts higher than target levels. All samples which had ATP
values below the specified level had bacteria counts below
the target levels. The rate of disinfection for TC, FC and
FS was similar to the rate of decrease of ATP. Thus, it
would seem that the use of ATP to control disinfectant addi-
tion is a valid possibility.
The first few steps were taken toward the development of an
ATP monitor for the above purpose. The stability of ATP
reagents used in an automatic monitor was evaluated. It was
found that the luciferin-luciferase reagent could not be
stored more than two days unless frozen. Further investiga-
tions on this question will be conducted under subsequent
phases of this program under U.S. Environmental Protection
Agency Grant No. S-802400.
Aftergrowth tests, conducted to determine the ultimate
bacterial and viral counts that might result in the receiving
water from the discharge of untreated and disinfected CSO,
showed no measurable increases during and up to three days.
These results were felt to be more indicative of the inability
to simulate receiving water conditions in the laboratory rather
than a lack of aftergrowth. Breakpoint chlorination was
shown to give target bacteria and viral reductions and ammonia
removal, but the costs may be a prohibitive factor.
The results of the bench-scale studies were meant to serve as
a basis to design the full-scale demonstration facilities.
However, because many questions remained unanswered, the
demonstration facilities were constructed with as much flex-
ibility as possible in order to verify the bench-scale find-
ings. The effectiveness of Cl2 and C102 in single- and two-
stage disinfection is to be determined with particular emphasis
on mixing. Suspended solids removal prior to disinfection is
to include micro-screening (23 micron aperture), fine-mesh
screening (71 and 105 micron aperture) and swirl concentration.
The different methods of suspended solids removal are to be
129
-------
evaluated on a full-scale for simplicity of operation, effec-
tiveness of solids removal and minimization of disinfection
requirements.
130
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SECTION VII
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cology Aspects of C102 Application for the Treatment of
Water Containing Phenols. Sb. Vysoke Skoly Chem Technol
Froze Technol Vody. 8:327-346, 1965. Chem Abstr. 65:1960d.
136
-------
67- Morris, J.D. Aspects of the Quantitative Assessment of
Germicidal Efficiency. Harvard University (Presented at
American Chemical Society Meeting, Chicago, August 26-31,
1973).
68. Baker, R.J. Engineering Considerations in Disinfection.
In: Proceedings of the National Specialty Conference on
Disinfection, American Society Civil Engineers. New York,
July 8-10, 1970. p. 683-697.
69. Lewis, R.N. Proceedings of the First Microbiology Seminar
on Standardization. U.S. Environmental Protection Agency-
Washington, D.C. Publication Number R4-73-022. March
1973. p. 137.
70. Van Dyke, K., R. Stitzel, T. McClellan, and C.
Szutkiewicz. Automated Analysis of ATP; Its Application
to On-Line Continuous-Flow Incubations and Measurement
of ATP-Coupled Enzyme Systems. In: Advances in Automated
Chemistry, Volume I. Tarrytown, New York, Technicon
Corporation. 1969. p. 47-53.
71. Nutrient Removal Using Existing Combined Sewer Overflow
Treatment Facilities. O'Brien & Gere Engineers, Inc.,
Syracuse, New York-Project Number 115.238, Dept. of
Public Works, Div. of Drainage & Sanitation, County of
Onondaga.
72. Smisson, B.S. Design, Construction and Performance of
Vortex Overflow; Symposium on Storm Sewage Overflows.
Institution of Civil Engineers, 1967. p. 99.
73. Swirl Concentrator As a Combined Sewer Overflow Regulator
Facility. U.S. Environmental Protection Agency, Office
of Research and Monitoring. Washington, D.C. Report
Number EPA-R2-72-008. September 1972. 179 p.
74. Field, R. Dual Functioning Swirl Combined Sewer Overflow
Regulator/Concentrator. U.S. Environmental Protection
Agency, National Environmental Research Center,
Cincinnati, Ohio. Report Number EPA-670/2-73-059.
September 1973. 49 p.
75. Sullivan, R.H., M.M. Cohn, J.E. Ure, F.E. Parkinson, and
G. Galiana. Relationship Between Diameter And Height For
The Design of A Swirl Concentrator As A Combined Sewer
Overflow Regulator. U.S. Environmental Protection Agency,
Research Center, Cincinnati, Ohio. Report Number EPA-
670/2-74-039. July 1974. 44 p.
137
-------
76. Sullivan, R.H., M.M. Cohn, J.E. Ure, and F.E. Parkinson.
Swirl Concentrator As A Grit Separator Device. U.S.
Environmental Protection Agency, National Environmental
Research Center, Cincinnati, Ohio. Report Number EPA-
670/2-74-026. June 1974. 93 p.
77. High-Rate Filtration of Combined Sewer Overflows. U.S.
Environmental Protection Agency, Office of Research and
Monitoring. Washington, B.C. Report Number 11023 EYI 04/72,
April 1972. 339 p.
78. Demonstration of Rotary Screening for Combined Sewer
Overflows. U.S. Environmental Protection Agency, Office
of Research and Monitoring. Washington, D.C. Report
Number 11023 FDD 07/71. July 1971. 55 p.
79. Hypochlorite Generator for Treatment of Combined Sewer
Overflows. U.S. Environmental Protection Agency, Office
of Research and Monitoring. Washington, D.C. Report
Number 11023 DAA 03/72. March 1972. 89 p.
80. Liskowitz, J.W., and G.J. Franey. Measurement of Suspended
Solids Concentrations in Sewage by a Depolarization Method.
Env Sci Tech. 6(l):43-47, January 1972.
81. Storm Water Management Model, Volume I-Final Report. U.S.
Environmental Protection Agency, Water Quality Office.
Washington, D.C. Report Number 11024 DOC 07/71. July 1971.
352 p.
82. Storm Water Management Model, Volume II-Verification and
Testing. U.S. Environmental Protection Agency, Water
Quality Office. Washington, D.C. Report Number 11024 DOC
08/71. August 1971. 172 p.
83. Storm Water Management- Model, Volume Ill-User's Manual.
U.S. Environmental Protection Agency, Water Quality Office.
Washington, D.C. Report Number 11024 DOC 09/71. September
1971. 359 p.
84. Storm Water Management Model, Volume IV-Program Listing.
U.S. Environmental Protection Agency, Water Quality Office,
Washington, D.C. Report Number 11024 DOC 10/71. October
1971. 249 p.
138
-------
SECTION VIII
LIST OF PUBLICATIONS
1. Murphy, C. B., Jr., and E. C. Tifft. A Novel Application
of Electron Spin Resonance; The Analysis of Chlorine
Dioxide in Waste-water. O'Brien & Gere Engineers, Inc.
(Presented at the 5th Northeast Regional Meeting,
American Chemical Society, Rochester, N. Y., October
14-17, 1974.) 13 p.
2. McVea, J. L. Virus Inactivation of Chlorine Dioxide
and Its Application to Stormwater Overflow. Syracuse
University, Master's Thesis. November 1972, 90 p.
3. Smith, J. E., and J. L. McVea. Virus Inactivation by
Chlorine Dioxide and Its Application to Stormwater
Overflow. Syracuse University. (Presented at the 166th
American Chemical Society National Meeting, Chicago,
August 26-31, 1973.) 9 p.
4. Smith, J. E., and J. L. McVea. Virus Inactivation by
Chlorine Dioxide and Its Application to Stormwater
Overflow. Water Res. (Submitted for publication 1974.)
5. Tifft, E. C., S. L. Richardson, P. E. Moffa, and R. Field.
Disinfection Techniques For Point-Source Treatment of
Combined Sewer Overflows. O'Brien & Gere Engineers, Inc.
(Presented at the 1974 Spring Meeting of the New York
State Water Pollution Control Association. Kiamisha
Lake, N. Y., June 21-23, 1974.) 11 p.
139
-------
SECTION IX
LIST OF ABBREVIATIONS
CSO
SCSO
C102
Cl~
cio-
C102~
cio3-
HOC1
CDS
Dosage
Br2
Cd
Cr
Cu
Fe
Hg
Ni
Pb
Zn
03
UV
esr
g
G
G'
GHZ
K
fg
M
biphasic
fps
cfs
I/sec
mg/1
ug/1
rpm
mgd
l/min/m2
Combined Sewer Overflow
Simulated Combined Sewer Overflow
Chlorine
Chlorine Dioxide
Chloride Ion
Hypochlorite Ion
Chlorite Ion
Chlorate Ion
Hypochlorous Acid
Chlorine Demanding Substances
Quantity sufficient to yield an initial
concentration (often used interchangeably
with Dose)
Bromine
Cadmium
Chromium
Copper
Iron
Mercury
Nickel
Lead
Zinc
Ozone
Ultraviolet
Electron Spin Resonance
Magnetogyroscopic Ratio
Gauss
Velocity Gradient
Megahertz
Kilocycles per second
10
-15
gram)
femtogram (1 fg1 =
Molar
two-phase
feet per second
cubic feet per second
liters per second
milligram per liter
microgram per liter
revolutions per minute
million gallons per day
liters per minute per square meter
(application rate)
140
-------
e
TS
TSS
VS
vss
Sett-S
TOC
COD
T-ALK
T-IP
NH3N
TKN
ORGN
N02N
NQ3N
N02N03
N
OT
P
Thio
DPD
MF
MPN
TC
FC
FS
E. coli
ATP
MOPS
PFU
Bacter iophage ,
phage
f2
0X174
polio-1
HSV-L2
NDV
Vaccinia
Coxsackie B-3
YFV
ECHO- 7
GKN
TPB
CsCl
MgS04
EDTA
HEp-2
Density
Total Solids
Total Suspended Solids
Volatile Solids
Volatile Suspended Solids
Settleable Solids
Total Organic Carbon
Chemical Oxygen Demand
Five-Day Biochemical Oxygen Demand
Total Alkalinity in mg/1 Calcium Carbonate
Total Hydrolyzable and Orthophosphate in mg/1 P
Ammonia in mg/1 N
Total Kjeldahl Nitrogen in mg/1 N
Organic Kjeldahl Nitrogen in mg/1 N
Nitrite in mg/1 N
Nitrate in mg/1 N
Nitrite plus Nitrate in mg/1 N
Nitrogen
Orthotolidine
Phosphorous
Sodium Thiosulfate (Na2S203•5H20)
N, N-Diethyl-p-phenylenediamine
Membrane Filter
Most Probable Number
Total Coliform Bacteria, T Coli,
Fecal Coliform Bacteria, F Coli,
Fecal Streptococcus Bacteria, F.
Strep
Escherichia coli
Adenosine Triphosphate
Morpholinopropane Sulfanilic Acid
plaque forming units
Bacterial Virus
Bacteriophage f2
Bacteriophage 0X174
Poliovirus Sabine Type 1
Herpes Simplex Virus-L2
Newcastle Disease Virus
Vaccinia Virus
Coxsackie Virus B-3
Yellow Fever Virus
Echovirus-7, Enteric Cytopathogenic Human Orphan
Glucose Pottai~ium Nutrient
Tryptose Phosphate Broth
Cesium Chloride
Magnesium Sulfate
Ethylene Diamine Tetraacetic Acie
Human Epithelial Cell Line
Total Coli
Fecal Coli
Strep, Fecal
141
-------
gal gallon
U micron
hr hour
mon month
yr year
mgd million gallons per day
ft feet
v velocity
HC1 Hydrochloric Acid
142
-------
SECTION X
APPENDICES
Page
A. Characterization of Combined Sewer Overflows 144
B. Tabulation of Data for Single-stage Disinfection
Studies 153
C. Derivation of Dilution Factors and Residence Times
for Aftergrowth Studies 164
D. Tabulation of Data for Two-Stage Disinfection
Studies 166
E. Tabulation of Data for Aftergrowth Studies 171
143
-------
APPENDIX A
CHARACTERIZATION OF COMBINED SEWER OVERFLOWS
The data is a partial listing of the information obtained in
a characterization study of CSO in the City of Syracuse.
The purpose of their inclusion is to demonstrate the
variable nature of CSO. The key to identification of the
computer printouts is as follows:
STNO - Storm Number-approximately thirty storms were
sampled.
PLOC - Primary Location-several different overflow
sites were sampled. The two included here are
1 - Maltbie Street
2 - Rowland Street
SLOG - Secondary Location-different locations within
an overflow site, intended primarily for use in
the demonstration of treatment facilities.
1 - Untreated Overflow
2 - Receiving Water Upstream of Overflow
3 - Receiving Water Downstream of Overflow
10 - Lithium Solution used for flow measurement
TYPE -
0 - Grab
1 - Sequential or simple composite
N - Composite - Number tells actual number of
sequentials included in sample
SQNO - Sequence Number-gives the order in which
samples were taken during a storm; 0 indicates
a time of pre-overflow rain
SAMP - Sample Number-an arbitrary number assigned to aid
in analytical bookkeeping
FLOW - Flowrate in mgd
RAIN - Accumulated rain in inches
RAININT - Rain intensity during the previous interval in
inches per hour
144
-------
Table A-l.
REPORT PRINTED 2/28/73 PAGE 7 - 1
'»YKAC1)SE COHiilNI-ri SEUEM. UVEI'.PI.OUS PRELIMINARY PHASf
STNO PLOC SLCC TVPF. SQNO SAMP
DATE
TIW
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PH
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Table A-2.
115201517
REPORT PRINTED 2/28/73 PAGE
7-2
SYF'.ACUSE COMBINED SEl.EP. rvERF-LOUS PRELIMINARY PHASE
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1.40
0.72
1.21
0.70
C.47
1.74
0. 35
0.76
1.31
0.7ft
0.79
8.
10.
10.
7.
6.
7.
4.
10.
11.
16.
20.
23.
25.
32.
36.
44.
46.
52.
54.
53.
53.
46.
5?.
57.
5-3.
64.
54.
66.
69.
77.
Ti.
-------
Table A-3.
115201517
REPORT PRINTED 2/28/73 PAGE
9-1
SYRACUSE COHaiNED SEWER OVERFLOWS PRELIMINARY PHASE
srr40 PLOC sure TYPT- soro
DATF
FLOW
RAIN RAININT
PH
T-CULt
TOG COD
TSS
vss
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
3
3
T
1
3
3
3
3
3
-?
T
3
3
3
3
3
J
J
3
3
3
3
7
j
3
3
3
3
^
3
3
^
3
3
T
3
3
3
3
1
1
1
I
1
1
1
1
1
1
1
1
1
]
1
1
1
1
1
1
1
1
1
1
1
1
J
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
]
1
1
1
I
1
1
1
]
1
I
1
1
1
1
1
1
1
I
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
4
5
6
7
n
9
in
11
12
13
14
15
16
17
1°
10
"MJ
21
22
.-3
24
i c^
,'6
21
S°.
2 1
3il
31
32
33
14
1-i
"V,
'7
"i^
3T
41!
41
280
?n]
2 fi 1
2 Lii
'->R4
r (i 5
2:i6
?R7
?e-:
••3')
?-90
?in
29 2
29 <
2'34
29'-
106
Vy7
"9>1
29 )
300
301
'. 1?
33 1
334
33-1
336
3W
338
33 )
Mt-:~.
"t \
?'l J
14 1
i4'i
1'l'j
146
347
)4.!
6/30/72
6/30/7?
j/Jf/72
6/3C/7?
'./•J.fl/7,">
6/ )n/72
6/3C/ /?
6/30/72
6/ *C/72
6/TV7?
6/3I-/7?
L/T,/ f2
6/3C/7?
6/1C/7'
6/3C/72
4/ 30/7?
6/3C/72
••••/JC/7.?
6/ iT/72
6/W72
i,/ JO/72
6/3'5/7?
6/3'/ ?2
6/31 /7?
6/K. /72
•'. / 3 0 / 7 2
,',/!C/72
',/ !"./7J
(./1(. /7?
;./30/7?
6/ 1C/72
-./ 1' /7P
6 / 1 r / 7 .'
6/3T/7?.
• / 3 r. / / '
' / '. i ' / 7 ,">
7 / 1 / f ?
7/ 1/7?
7 / 1 / / ?
446
son
515
530
545
600
615
630
645
700
715
730
745
noo
.115
(130
S45
90n
915
910
94^
1000
110"
] 200
1300
1400
I SOU
1601
1700
UOO
190 )
'00')
MO''.
2?or
:'3.i '
?4'J 1
KM
70'
301
11.530
10.1150
10.100
ti.OI'.O
10. If."
10.ll\)
8.9«0
8 . o •: o
6. 730
5.780
5.730
'i.C'jO
4.040
3. 3;.o
3.360
'.7iO
3. 110
3.110
3.110
3.) 10
1.110
3. 110
?.OVl
l.BCO
l.SCO
1 .300
1. 700
1.700
i ..icn
1.700
1 .I'OO
1 .7-.')
1.910
1. 750
1. J- "l
1.7 •')
l.'it-O
1 . 7-3(1
1 . S >0
0.95
l.OS
1.05
1 .05
1.10
1.10
1.10
1.10
1. It!
1.10
l.Ui
1.1"
1.10
1 .10
1. 10
1.15
1.15
1.15
1 .15
1.15
1.15
1.15
1.15
1.15
1.15
1.15
1.20
i.?n
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1 .20
1.21
c.oo
0.40
o.oc
O.Ol!
0.20
O.QC
0.00
C.O.I
O.no
0.00
0.00
o.ou
0.00
0.00
0.00
0.20
0.00
0.00
o.oo
0.00
0.00
0.00
O.Ou
0.00
0.00
o.oc
0.05
0 . O'O
c.oc
0.00
o.oo
o.ou
C.O 1
c.oo
0.00
0.00
0.00
r.oo
o.oo
7.6
7.6
7.7
7.9
7.4
7.7
7.9
M. 1
b.O
7.4
7.1
7.9
7.9
'{.0
7.6
7.5
7.6
7.2
7.7
7.M
7.9
7.3
7.-1
6.9
7.5
7.6
7.6
7.5
7.5
7.6
7.H
7.9
7.7
7.6
7.7
a.o
H.O
7.C
670000.
500000.
1C-JOOOO.
8100PO.
130000.
leoot.i).
14001 0.
700CO.
1800CO.
1000'JT.
70000.
15 oo no.
40000.
22001;.').
240000.
180CO.
120CO.
19000.
900n.
,'5000.
70CO.
i2CO';o.
1 20000.
90000.
1100'JO.
I30oi;o.
60000.
vgoo^o.
3 10300.
260000.
200000.
2 U1000 .
330000.
2 60'! 00.
1900CO.
400000.
-; loooo.
10.
B.
10.
10.
12.
12^.
11.
10.
11.
13.
11.
13.
14.
13.
12.
16.
15.
14.
12.
13.
12.
14.
17.
1«.
18.
23.
22.
21.
24.
26.
23.
2b.
26.
25.
1^.
16.
12.
20.
5.
3.
3.
4.
5.
4.
3.
7.
4.
8.
8.
11.
12.
11.
13.
15.
18.
12.
18.
16.
17.
19.
17.
17.
15.
19.
16.
17.
20.
17.
19.
21.
18.
17.
14.
12.
12.
115.0
135.0
125.0
120.0
125.0
182.0
110.0
175.0
185.0
165.0
145.0
140.0
135.0
115.0
110. 0
105.0
125.0
120.0
100.0
140.0
145.0
33.0
?3.0
20.0
20.0
15.0
27.0
19.0
13.0
?7.0
21.0
32.0
10.0
10.0
17.0
14.0
12.0
0.0
5.0
0.0
0,0
0.0
120.0
0.0
45.0
40.0
40.0
0.0
35.0
25.0
30.0
35.0
35.0
40.0
35.0
25.0
85.0
55.0
13.0
2ij.O
18.0
7.0
10.0
20.0
10.0
11.0
13.0
12.0
11.0
3.0
5.0
11.0
4.0
5.0
-------
Table A-4.
115201517
REPORT PRINTED 2/28/73 PAGE
9-2
SYRACUSE COMB 1 NED SCWE1! uVEitFLDHS PRTLIMINARY PHASl"
STNO PLOC SLOG TYPfi SQi\0
DATE
T1 V f
TKN
IJRGN
N02N N03t-i
TALK
T-tP
CL
00
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
3
3
3
3
n
3
3
3
3
3
3
3
3
3
3
3
3
3
3
1
3
3
3
3
3
3
5
3
3
3
3
1
3
3
3
3
3
3
)
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
I
1
1
1
1
1
1
I
1
1
I
I
1
1
1
1
1
I
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
I
I
1
1
1
1
1
I
t
I
1
3
i,
5
6
7
b
9
in
11
12
13
14
15
16
i 7
19
19
?0
21
??
?3
24
25
76
27
7 ^
2')
30
!1
32
33
34
35
36
37
T '
39
£<-
41
280
?« I
?fl?
2,'. 3
7P4
794
?S6
2F.7
i1 3 .•)
.? a 9
290
291
2-J2
293
,-•'94
2 95
796
297
vy,:
79')
300
3.11
33''
33 i
334
33 5
336
337
33a
339
340
341
.J42
34 3
144
340
Ui6
?4 7
< '. -i
6/30/72
o/TJ/72
7/ I//:'
7/ !/T'
?/ 1/7'
445
500
51-1
530
5 4 5
600
615
630
645
700
71=5
730
745
300
nis
830
845
90^
91b
930
945
1000
lion
1200
130J
140"
1500
1600
1 70.1
1.-100
1900
?'i 1C
2100
2200
v-jnr,
?4( .;
1' ''
T 1 i
3'
1.2
1.2
1.1
1.?
1 .0
1 .4
1.0
1 .3
1.9
2.0
Z.1!
2.5
3.5
4.6
5.2
4.5
3.9
4.2
4.0
4. a
4.4
4.4
4.7
4.1
3.9
3.4
3.'i
4.0
4.1
?.:j
2.3
2. 7
3 . ~i
2.'
3. .
'.4
1. i
0.25
0.25
0.30
0. i:;
0 . ••' 8
0 . ? 5
0.25
0 . 4 !)
0.55
0.65
O.'iS
1.0 -j
2.02
3..!3
3.52
2.30
2.70
2.70
2.62
3.70
3.12
3.02
2. '8
l.')3
1.43
1 .30
l.:?6
1.15
1 . ft r-
1 .65
1.68
2.?u
2.5C
1.30
1 .7fi
?.45
1 . i: 5
•;.7'j
0.9
0.9
o.a
0.9
0.7
1.1
0.7
•>.9
1.3
1.3
1 .6
1.4
1.5
0.9
1.7
2.2
1.?
1.5
1.4
1.1
1.3
1.4
2.4
2.2
?.5
2.1
2.1
2.13
2.4
1.1
0.6
•1. 5
1.1
0.9
1 .0
0.9
1 .7
'.' • W'
0.11
0.11
0.11
C.14
(1.15
0. 14
0.17
n.l8
0.21
0.22
0.23
C.26
0.28
0.30
0.33
0.34
0.34
0.39
0.38
0.39
0.46
0.52
0.31
0.34
0.34
0.34
U. 3'J
o.3a
0.35
0.5,3
0.41
0.3'5
0.36
0.34
''. 35
(..34
'.34
r.. 14
0.016
O.:ll4
0.016
0.016
0.01 9
0.019
0.019
0.0?1
0.021
0.021
0.026
0.029
0.0,79
0. i31
0.031
0.031
0.0 6 5
0 . D 5 0
0.060
O.GflS
0. 117
0.105
0. 14')
0.036
0.:336
0.036
0.054
0.054
n.r.31
0. 104
0.052
0.^4 7
0.700
0.041
0. !31
o . v,; 1
O.'TM'
l).0?0
n.O-')
0.10
0.09
0.12
0.13
0.12
0.1S
0.16
O.H
0.20
0.2''
0.23
0 . 2 'j
0.27
0.3'i
0.31
0.27
0.34
0.32
0.30
0.34
0.41
0.27
0.30
0.30
0.3J
0.33
0.33
0.32
0.40
0.36
0.30
0.16
0.30
0.3;'
0.31
0.3"
•)-32
125.
126.
149.
159.
150.
274.
785.
232.
230.
?34.
236.
?38.
247.
246.
253.
255.
253.
255.
259.
257.
259.
259.
259.
257.
257.
249.
247.
261.
?cS .
,'60.
255.
0.12
0.11
0.13
0.11
0.12
0.12
0. 13
C.16
0.19
0.22
0.?9
0.27
0.53
0.53
0.57
0.51
O.i>l
0. 73
0.54
l.Cfl
0.95
1.26
1.19
1.22
0.66
1.06
1.77
0.94
0.53
0.48
0.54
0.50
0.37
0.52
0.73
0.39
0.19
J.29
23.
27.
33.
37.
32.
36.
78.
82.
81.
85.
85.
85.
86.
SB.
83.
83.
83. •
89.
92.
9?.
92.
93.
92.
93.
88.
9 J.
89.
89.
92.
93.
92.
91.
-------
Table A-5.
115201517
REPORT PKINTED 2/28/73 PAGE 11 - 1
SYPACUSE COMBINED SEhPR L'VEftFLOWS PRELIMINARY PHAStf
STNO PLOC SLOC TYPE SO;tO SAM0
DATt
T IM. l;
rt.MN KA1NINT
T-CCLI
TOG
COO
TSS
VSS
5
5
5
5
'j
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
1
I
I
1
]
1
I
1
1
I
I
1
1
1
1
I
1
I
1
1
1
1
1
1
1
1
i
I
1
1
1
1
1
1
1
1
1
1
1
2
3
10
0
0
1
1
1
1
1
1
1
I
1
1
I
I
1
1
1
15
1
1
0
0
1
2
3
A
5
6
7
8
q
10
11
12
13
14
15
1
1
1
1
13.;4
1385
35)
360
361
36?
363
364
3ob
J66
367
3<>8
36-7
37"
371
37 '
373
3tl3
33'i
3 '1 -j
11
7/
7/
r/
7/
7/
7/
7/
7/
7/
7/
?/
7/
7/
7/
7/
7/
7/
7/
7/
7/
7/
7/72
7/72
7/72
7/72
7/72
7/72
7/72
7/72
7/7?
7/72
7/72
7/72
7/7?-
7/7?
7/72
7/72
7/72
7/7?
7/72
7/72
7/72
1530
1545
160 ;
1615
163P
1645
17CK:
1715
1730
174S
1HOO
1R15
1 330
1 H45
190i!
1915
193-1
193
193C
1930
1930
11.600
U.70U
4.970
2.900
i.sto
0.9 '50
0.760
0.390
0.?YO
0.220
0 . 1 ' C
0.140
0. l?0
O.CllQ
O.O.TO
150.000
0.00
0.20
0.40
0.40
0.40
',.40
C.40
0.40
0.4!)
0.40
0.40
0 . 4 0
0.40
0.40
0.40
0.40
0.40
0.4T
(J . H 0
0.:J(1
0.01'
0.00
O.OU
O.OU
C.or.
0.00
c.ou
0.0.1
o.oo
0.00
0.00
o.oo
0 . 0 J
0.0';
0 . H f ;
6. a
7.0
7.?
7.1
7.0
7.2
7.]
7.3
6.7
6.0
6.5
6.6
6.6
6.6
C
7.4
7.6
1950000.
2120000.
17HOOOO.
360000.
490000.
4i omo.
V600CJO.
100000.
""0000.
4BOCO!-0.
6300000.
170GOOC.
8.-JOOOOO.
^toooooo.
850COO.
loooooo.
11.
16.
63.
10.
40.
16.
17.
13.
250.
555.
50.
41.
32.
91.
5.
6.
30.
36.
116.
37.
37.
47.
36.
34.
1060.
1750.
129.
64.
67.
150.
24.
24.
715.0
615.0
325.0
275.0
IB5.0
175.0
110. 0
185.0
175.0
170.0
li,5.0
82.5
23?. 5
2W.O
230.0
160.0
142.0
116.0
110. 0
80.0
180.0
165.0
170.0
16U.O
70.0
100.0
-------
Table A-6.
I15?01517
REPORT PRINTED 2/28/73 PAGE 11-2
SYRACUSE CUMBINED StjHER UVERH.OHS PKKLIMINARY PH/\SI5
STNQ PLOC SLOG TYP!-. SONO
DATE
Tit*1-
MM IN Cl.tGN N02M03
N02N N03N TALK T- 1 P
CL
Ul
o
5
5
5
tj
5
F^
5
5
5
*>
5
r,
!)
3
5
5
ti
5
5
1 1 0
1 1 0
1 I 1
I 1 1
I 1 1
1 1 1
1 1 1
I 1 1
1 1 1
1 I 1
1 1 1
1 1 1
1 I I
1 1 1
1 1 1
1 1 1
I 1 I
1 1 15
I ? 1
1 1 1
1100
0
r
1
2
3
4
•5
6
7
R
•V
10
11
12
13
14
15
1
1
1
1
13H4
\ '.'15
,i5T
360
3hl
361:
36 1
36-i
11 (V 5
36o
167
368
36')
.570
371,
37',!
371
3>13
IK 4
305
11
7/
7/
//
7/
7/
11
!/
7/
//
7/
It
'It
It
7/
7/
7/
7/
7/
7/
7/
I/
ItlZ
7/72
7/72
?/72
7/7?
7/72
7/72
in?.
7/7?
7/72
7/72
7/72
7/72
7/7.1
7/72
7/7?
7/72
7/72
7/7?
7/72
7/7,?
1, 531'
I 5/i 5
1600
161 r>
163 i
164 r'
170')
1713
173'1!
17Vi
). 100
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1130
I.IA5
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n . 4 p
0 . ') t!
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0.96
1 . V)
1.72
1.26
? . 20
0.66
0.56
0,
-------
Table A-7.
115201517
REPORT PRINTED 2/28/73 PAGE 26-1
SYRACUSE CObHlNEO SfWER nVGUFLm.'S PRELIMINARY PHASH
STNO PI.or, su:c TYPK so NO S\MI>
DATE
Tl MI-
FLOW
RAIN WAlNINf
PH
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cno
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4070000.
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127.
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153.
16.
73.
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25.
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50.
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53.
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47.
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134.0
190.0
596.0
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29.0
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52.0
16.0
34.0
in
H
-------
Table A-8.
115701517
REPORT PRINTED 2/23/73 PAGE 26-2
SYRACUSE COMBINED SEWER UVE.V LOUS PRELIMINARY PHASE
STNO f'LOC SLUG TYPE SONO
C.ATI:
TINT
TKM
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4.52
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3.66
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2.52
3.64
3.90
4.52
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4.91
5.35
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7.95
7.49
0.31
0.40
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0.15
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0.35
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0.53
0.52
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0.37
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0.01
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0.46
0.44
1 .190
0.558
0.070
0.054
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0.146
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0.287
0.576
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733.
0.42
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1.43
1.08
1.70
2.26
2.25
2.89
3.95
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3.19
0.03
0.15
77.
83.
57.
31.
19.
37.
48.
60.
6cJ.
64.
611.
77.
78.
77.
73.
71.
96.
79.
-------
APPENDIX B
TABULATION OF DATA FOR SINGLE-STAGE DISINFECTION STUDIES
This data is the basis for the graphs of bacteria shown in
Figures 11, 12, 15, 16 and 25.
153
-------
Table B-l. Effect Of
On An Unscreened Effluent
Dosage (mg/1)
Contact
time
(sec)
0
30
60
120
180
300
Contact
time
(sec)
0
30
60
120
180
300
0
TCa
5,580,000
4,800,000
6,160,000
7,150,000
9,240,000
5,940,000
16
TC
5,580,000
715,000
209,000
187,000
2,200
3,300
FS
98,500
97,900
103,400
85,800
100,000
93,500
FS
98,500
34,100
55,000
30,800
11,700
9,460
4
TC FS
5,580,000 98,500
1,760,000 83,500
3,540,000 103,000
1,254,000 73,700
4,900,000 72,600
2,750,000 49,500
Dosage (mg/1)
20
TC - FS
5,580,000 98,500 5
616,000 24,200
11,000 23,000
5,940 12,540
660 6,930
320 3,740
TC
5,580,000
4,620,000
1,450,000
1,045,000
1,023,000
418,000
TC
,580,000
37,400
16,500
6,820
5,170
4,500
8
FS
98,500
108,900
74,800
46,200
41,800
13,200
25
FS
98,500
1,210
990
913
143
460
12
TC FS
5,580,000 98,500
583,000 77,000
275,000 55,000
242,000 38,000
74,800 20,300
29,000 12,000
a all bacterial data represent counts/100 ml
-------
Table B-2. Effect Of Cl2 On An Unscreened Effluent
Ul
Dosage (mg/1)
Contact
time
(sec)
0
30
60
120
180
300
Contact
time
(sec)
0
30
60
120
180
300
TCa
5,000
6,050
15,400
4,620
6,050
5,280
TC
5,000
3
,000
,000
,000
,000
,000
,000
,000
,850
220
860
120
120
0
FS
105
96
126
96
79
101
16
105
1
,000
,800
,500
,800
,200
,200
FS
,000
,100
110
20
66
27
TC
5,000,000
3,960,000
3,500,000
3,400,000
1,140,000
920,000
Dosage
TC
5,000,000
6,820
5,500
210
198
11
4
FS
105,
78,
73,
48,
44,
38,
(mg/1)
20
000
000
700
400
000
500
FS
105,
2,
000
200
110
99
11
0
TC
5,000
5,060
1,639
440
369
196
TC
5,000
11
8
,000
,000
,000
,000
,000
,900
25
,000
,000
560
590
980
85
FS
105,000
78,000
27,700
13,300
10,200
5,800
FS
105,000
2,750
170
120
88
46
12
TC FS
5,000,000 105,000
15,400 2,200
5,900 1,067
800 627
910 250
760 10
a all bacterial data represent counts/100 ml
-------
Table B-3. Effect Of Cl2 On An Effluent From A 23 Micron Screen
Contact
time
(sec)
0
30
60
120
180
300
0
TCa
3,970
5,390
2,860
5,280
8,390
3,090
,000
,000
,000
,000
,000
,000
FS
96,700
97,900
103,400
82,500
105,600
101,200
TC
3,970
4,950
3,861
1,199
946
165
,000
,000
,000
,000
,000
,000
Dosage
Contact
time
(sec)
0
30
60
120
180
300
TC
3,970
913
165
5
16
,000
,000
,000
,500
330
209
FS
96,700 3
49,500
30,800
5,610
1,980
485
TC
,970,
693,
4,
3,
3,
6,
000
000
000
500
400
900
Dosage
4
FS
96,700
89,100
84,700
68,200
79,200
64,900
(mg/1)
20
FS
96,700
34,100
15,730
4,400
1,155
220
(mg/1)
TC
3,970
1,870
297
531
50
2
TC
3,970,
326,
3,
2,
1,
1,
8
12
FS TC
,000
,000
,000
,400
,600
,420
96
59
31
17
22
2
25
,700 3,970,000
,400 539,000
,130 440,000
,930 22,000
,220 11,000
,915 220
FS
96,700
57,200
33,000
17,600
5,390
770
FS
000
700
400
200
200
430
96,
17,
2,
1,
700
900
200
012
209
121
a all bacterial data represent counts/100 ml
-------
Table B-4. Effect Of Cl2 On An Effluent From A 23 Micron Screen
Ln
Dosage (mg/1)
Contact
time
(sec)
0
30
60
120
180
300
TCa
3,130
3,100
450
1,880
3,300
2,300
,000
,000
,000
,000
,000
,000
0
FS
93,800
97,900
115,500
84,700
83,600
91,300
TC
3,130,
2,970,
1,320,
1,210,
188,
82,
000
000
000
000
100
500
Dosage
Contact
time
( sec)
0
30
60
120
180
300
TC
3,130
460
83
5
,000
,000
,600
,610
880
350
16
FS
93,800
19,580
15,620
7,040
5,610
110
TC
3,130,
6,
1,
000
380
200
198
110
270
4
FS
93,800
53,900
42,900
74,800
30,800
20,900
(mg/1)
20
FS
93,800
3,440
209
181
47
11
TC
3,130
2,300
380
120
3
TC
3,130
1
1
,000
,000
,000
,000
,700
660
2
,000
,980
,100
66
110
190
8
93
62
48
13
13
9
5
93
12
FS TC
,800 3,130,000
,700 1,870,000
,400 230,000
,200 34,000
,200 4,700
,460 490
FS
,800
220
220
33
22
22
FS
93,800
33,000
26,400
10,780
11,500
5,720
all bacterial data represent counts/100 ml
-------
Table B-5. Effect Of C102 On An Unscreened Effluent
Dosage (mg/1)
Contact
time
(sec)
0
30
60
120
180
300
TC
3,120
2,200
3,400
4,730
2,860
2,970
0
a
,000
,000
,000
,000
,000
,000
FS
126,000
99,000
119,900
101,000
114,000
114,400
TC
3,120
77
84
83
120
119
4
FS
,000
,000
,700
,000
,000
,000
Dosage
Contact
time
(sec)
0
30
60
120
180
300
TC
3,120
38
2
1
16
,000
,500
,300
,012
430
560
FS
126,000
418
230
66
33
11
TC
3,120
110
2
1
1
126 ,
4,
5,
2,
5,
5,
(mg/1)
20
000
400
720
860
060
600
FS
,000
,000
,640
,078
297
,180
126,
000
605
66
66
11
33
TC
3,120
44
27
31
5
1
TC
3,120
4
1
8
,000
,000
,000
,900
,500
,650
25
,000
,840
,430
440
649
480
12
FS TC
126,000 3,120,000
6,160 22,000
2,200 18,700
1,650 4,400
440 1,650
110 2,200
FS
126,000
437
495
16
11
16
FS
126,000
880
550
220
44
11
a all bacterial data represent counts/100 ml
-------
Table B-6. Effect Of C102 On An Unscreened Effluent
Dosage (mg/1)
Contact
time
(sec)
0
30
60
120
180
300
0
TCa
9,230
4,950
4,290
6,270
6,050
,000
,000
,000
,000
,000
FS
163
165
220
159
189
,000
,000
,000
,000
,200
TC
9,230,
6,380,
3,960,
2,640,
3,300,
4
000 163
000 135
000 94
000 67
000 95
FS
,000
,300
,600
,100
,700
TC
9,230
510
440
550
440
8
,000
,400
,000
,000
,000
FS
163,000
33,000
33,000
24,640
3,432
12
TC FS
9,230,000 163,000
144,100 10,560
166,.000 10,000
104,500 836
31,900 1,000
Dosage (mg/1)
Contact
time
(sec)
0
30
60
120
180
300
TC
9,230
51
44
35
60
16
,000
,700
,000
,800
,700
163
5
1
FS
,000
,280
,232
770
451
TC
No
20
data
FS
Available
TC
9,230
24
17
13
9
2
,000
,100
,600
,640
,350
5
FS
163,000
682
418
340
748
a all bacterial data represent counts/100 ml
-------
Table B-7. Effect of C102 On An Effluent From A 23 Micron Screen
Dosage
Contact
time
(sec)
0
30
60
120
180
300
0
Tca
5,390
6,000
4,950
6,050
4,950
6,700
,000
,000
,000
,000
,000
,000
FS
169,900
134,200
132,000
101,200
148,500
162,800
TC
5,390
340
220
169
144
123
4
(mg/1)
FS
,000
,000
,000
,400
,000
,000
Dosage
Contact
time
( sec)
0
30
60
120
180
300
TC
5,390
2
2
16
,000
,200
,310
286
154
99
FS
169,900
450
88
77
44
33
TC
5,390
2
2
3
169,
50,
74,
62,
53,
58,
Cmg/1)
20
900
600
800
700
900
300
FS
,000
,200
,500
,850
330
220
169,
900
340
132
429
11
44
8
TC
5,390,000
4,510
1,100
330
440
154
25
TC
5,390,000
6,160
1,375
506
520
231
12
FS TC
169,900 5,390,000
990 3,850
660 660
47 440
132 220
77 220
FS
169,900
605
320
132
55
22
FS
169,900
748
143
55
16
33
all bacterial data represent counts/100 ml
-------
Table B-8. Effect Of C102 On An Effluent From A 23 Micron Screen
Dosage
Contact
time
(sec)
0
30
60
120
180
300
0
TCa
5,382
4,180
3,850
5,720
5,830
3,960
,000
,000
,000
,000
,000
,000
FS
110
94
89
102
94
83
,600
,600
,100
,300
,600
,600
TC
5,382
99
47
40
34
47
4
(mg/1)
FS
,000
,000
,300
,700
,000
,300
Dosage
Contact
time
(sec)
0
30
60
120
180
300
5,382
7
5
2
1
16
,000
,700
,390
,285
,056
990
110
,600
330
11
22
11
11
5,382
5
4
2
1
,000
,060
,070
,200
946
,012
110,
5,
2,
1,
2,
1,
Cmg/1)
20
110,
600
060
200
980
400
870
600
110
22
0
0
00
8
TC
5,382,000 110
2,200
1,760
66
11
33
25
5,382,000 110
8,800
540
760
550
590
12
FS TC
,600 5,382,000
220 990
110 940
99 320
44 120
5 66
,600
286
9
11
0
0
FS
110,600
220
99
88
11
11
a all bacterial data represent counts/100 ml
-------
Table B-9. Temperature Effects On Bacteria During Disinfection With CLj
Cl_2 Dosage (mg/1)
Temp .
(°C)
2
23.5
30
Contact
time
(sec)
0
30
60
120
180
300
0
30
60
120
180
300
Q
30
60
120
180
300
8
Tca
7,300,000
3,400,000
2,100,000
1,100,000
560,000
61,000
1,025,000
4,400,000
1,610,000
200,000
100,000
15,000
13,800,000
11,600,000
2,400,000
290,000
60,000
75,000
FS
178,000
147,000
180,000
102,000
66,000
35,000
207,000
106,000
68,000
56,000
12,000
14,400
213,000
75,000
34,000
13,000
11,200
5,800
25
TC
7,300,000
106,000
46,000
19,000
189,000
800
10,250,000
70,000
9,000
2,100
450
200
13,800,000
65,000
71,000
3,900
5,000
1,020
FS
178,000
34,000
194,000
20,000
11,400
1,900
207,000
16,000
5,300
1,700
500
40
213,000
4,400
320
100
250
10
a all bacterial data represent counts/100 ml
-------
Table B-10. Temperature Effects On Bacteria During Disinfection With C102
CTi
u>
C102 Dosage (mg/1)
8
Temp Contact
(°C) time
(sec)
2 0
30
60
120
180
300
23.5 0
30
60
120
180
300
30 0
30
60
120
180
300
TCa
8,600,000
135,000
127,000
120,000
244,000
40,000
7,700,000
400,000
216,000
168,000
100,000
30,800
10,950,000
280,000
96,000
84,000
100,000
27,000
FS
155,500
73,000
28,000
9,300
7,000
3,200
179,500
17,000
8,900
6,200
7,300
2,600
208,000
41,800
9,500
7,200
5,600
2,280
25
TC
8,600,000
50,000
25,000
7,400
18,400
20,000
7,700,000
24,000
19,000
24,000
10,000
3,600
10,950,000
61,000
39,000
12,800
12,200
13,100
FS
155,500
3,870
1,600
1,300
10,600
9,500
179,500
3,050
1,250
670
360
1,250
20,800
2,520
940
970
1,800
1,100
a all bacterial data represent counts/100 ml
-------
APPENDIX C
DERIVATION OF DILUTION FACTORS AND RESIDENCE TIMES
FOR AFTERGROWTH STUDIES
1. Calculation of ratio of total overflow to dry-weather
Onondaga Creek flow
Qb = Average dry-weather Onondaga Creek flow at point of
entry to the City of Syracuse; i.e., before
occurrence of any CSO. From Reference 3, this is
taken to be 4500 cfs.
Qo = Total flow for those CSO discharging into Onondaga
Creek. For a maximum flow condition as taken from
Reference 1.
Qo = ciA1 where c = coefficient of runoff
= 0.20
i = rainfall intensity
=0.50 in/hr
A" = area of drainage basin
= 53,000 acres
Q0 - 5300 cfs
R! = ratio of Qb/Qo
= 4500 cfs ^
5300 cfs 1:
2. Calculation of maximum CSO residence time in Onondaga
Creek
T = residence time = distance from discharge of first
overflow into creek to entry into Onondaga Lake (D)
divided by creek velocity (v).
From Reference 3, D = 33,000 ft
v is calculated from the equation Q/A where
Q = Q0 + Qb/ and A is the average cross-sectional area of
the creek at time of maximum CSO.
From the Manning Equation.
Q = 1.49 X A X R2/3 X S1/2
Q = 9800 cfs
164
-------
Appendix C (Cont'd)
n = Manning's coefficient of friction = 0.025
A = trapezoidal cross-sectional area of creek with a
24-foot base as taken from Reference 1.
= 24 h + h2 where h = average creek depth
R = hydraulic radius
= A/PW where PW = wetted perimeter = 24 + 2.84h from
Reference 1.
S = slope of creek bed = 0.0015 in/ft from Reference 1.
Solving from h and subsequently A yields
A = 880 ft2
Therefore, v = 11.15 fps
T = 0.82 hour
- 1 hour
3. Calculation of ratio of total creek flow, including CSO
to Onondaga Lake
The total creek volume consists of 9800 cfs for the
duration of an average storm which is 400 minutes from
Reference 1. This quantity Vj_ is 1.76 x 109 gallons.
The volume (V^I of the epilimnion of the southern basin
of Onondaga Lake is 24.7 x 109 gallons. This quantity
is taken because this is the area of immediate impact on
the lake and consequently its selection will maximize
any effects.
R2 = dilution factor from creek to lake
= V2/V1 = 1/14.2 =1:14
165
-------
APPENDIX D
TABULATION OF DATA FOR TWO-STAGE DISINFECTION STUDIES
This data is the basis for the graphs of bacteria and ATP in
Figures 29, 30, 32 and 33.
166
-------
Table D-l. Two-Stage Disinfection Results
Including ATP-Bacteria Correlations
Dosage
(mg/1)
C102
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
C102
0
2
2
2
2
2
2
0
0
2
2
2
2
2
0
4
4
4
4
4
4
0
0
4
4
4
4
4
Contact
time
(sec)
0
15
30
45
60
90
120
0
15
30
45
60
90
120
0
15
30
45
60
90
120
0
15
30
45
60
90
120
Bacteria
(counts/100 ml)
TC
6,380,000
407,000
165,000
22,000
49,500
22,000
5,000
4,840,000
1,430,000
1,056,000
16,500
14,300
11,000
5,500
2,860,000
715,000
29,500
7,700
3,300
1,100
770
4,180,000
1,045,000
836,000
16,500
2,640
1,430
480
FC
615,000
63,500
11,000
4,620
3,300
2,200
2,300
594,000
231,000
116,600
7,240
3,520
2,200
1,540
308,000
41,800
1,850
460
2,200
660
405
322,000
97,000
52,000
1,100
600
250
60
FS
99,000
92,400
77,000
39,600
33,000
16,500
24,900
110,000
86,900
77,000
40,700
18,700
8,580
2,970
77,000
67,100
36,300
1,100
900
770
220
114,300
91,300
83,600
11,000
3,310
540
385
ATP
(arbitrary
units)
50.82
22.44
10.89
7.89
5.98
4.56
3.00
50.27
25.30
30.25
7.77
5.20
3.19
1.64
19.25
8.40
1.54
0.65
0.54
0.40
0.44
18.48
10.78
9.92
0.78
0.48
0.33
0.27
167
-------
Table D-2. Two-Stage Disinfection Results
Including ATP-Bacteria Correlations
Dosage
(mg/1)
C102
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
C102
0
2
2
2
2
2
2
0
0
2
2
2
2
2
0
4
4
4
4
4
4
0
0
4
4
4
4
4
Bacteria
(counts/100
ml)
Contact
time
(sec)
0
15
30
45
60
90
120
0
15
30
45
60
90
120
0
15
30
45
60
90
120
0
15
30
45
60
90
120
TC
1,870,000
340,000
9,999
8,800
9,900
2,200
999
1,430,000
80,300
18,700
4,070
2,970
2,899
2,899
803,000
28,600
880
880
580
410
275
1,122,000
126,000
19,250
1,100
460
250
120
FC
39,600
1,100
999
110
110
330
77
29,700
1,760
360
66
77
77
55
24,750
550
20
10
10
10
0
880
440
440
0
20
0
0
FS
121,000
30,800
10,000
2,530
2,640
1,430
1,100
129,800
57,200
14,850
2,860
1,590
1,100
350
130,900
14,300
1,180
820
600
300
280
124,000
28,300
6,999
1,200
500
385
120
ATP
(arbitrary
units)
31.57
5.00
1.13
0.83
0.56
0.46
0.46
19.47
4.33
1.89
0.86
0.52
0.45
0.36
24.97
3.19
1.21
0.75
0.49
0.00
0.00
20.24
5.21
0.57
0.00
0.00
0.00
0.00
168
-------
Table D-3. Two-Stage Disinfection Results
Including ATP-Bacteria Correlations
Dosage
(mg/1)
C12
4
4
4
4
4
4
4
4
-4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
ClOo
£
0
2
2
2
2
2
2
0
0
2
2
2
2
2
0
4
4
4
4
4
4
0
0
4
4
4
4
4
Contact
time
Csec)
0
15
30
45
60
90
120
0
15
30
45
60
90
120
0
15
30
45
60
90
120
0
15
30
45
60
90
120
Bacteria
(counts/100 ml)
TC
3,430,000
572,000
113,300
473,000
123,000
1,100
52,800
2,220,000
924,000
506,000
187,000
62,700
132,000
75,900
1,870,000
1,870,000
406,500
176,000
187,000
80,300
59,400
2,640,000
1,430,000
1,045,000
143,000
96,800
60,500
13,200
FS
308,000
84,700
59,400
82,500
40,700
38,500
12,100
110,000
86,900
74,800
38,500
39,600
40,700
13,200
112,600
84,700
18,700
8,800
5,500
8,910
6,160
109,900
47,300
56,100
102,300
8,800
4,180
3,410
ATP
(arbitrary
units)
45.21
35.31
32.01
31.35
26.84
29.37
26.73
38.72
29.37
27.72
27.28
23.32
20.02
19.80
25.96
18.15
10.34
6.82
6.83
6.07
5.34
13.31
16.83
10.23
4.33
2.02
2.92
2.26
169
-------
Table D-4. Two-Stage Disinfection Results
Including ATP-Bacteria Correlations
Dosage
(mg/1)
C12
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
cio2
0
2
2
2
2
2
2
0
0
2
2
2
2
2
0
4
4
4
4
4
4
0
0
4
4
4
4
4
Contact
time
(sec)
0
15
30
45
60
90
120
0
15
30
45
60
90
120
0
15
30
45
60
90
120
0
15
30
45
60
90
120
Bacteria
(counts/100 ml)
TC
187,000
121,000
90,000
1,100
1,210
660
110
220,000
61,600
4,400
1,100
330
99
99
660,000
999
99
99,999
18,700
110
99
FC
12,100
1,430
99
99
99
99
9
9,900
2,420
2,250
320
165
9
11
30,250
220
9
22,500
3,630
90
9
FS
82,500
38,500
2,200
3,300
3,850
1,980
1,870
72,900
17,600
3,300
999
2,750
1,980
1,320
11,000
999
99
74,800
8,800
110
44
ATP
(arbitrary
units)
7.22
10.30
2.75
2.93
1.24
0.70
0.55
9.60
6.06
1.45
1.46
0.74
0.73
0.65
10.01
7.11
0.89
0.49
0.27
0.39
0.27
8.17
10.21
5.20
0.52
0.35
0.25
0.19
170
-------
APPENDIX E
TABULATION OF DATA FOR AFTERGROWTH STUDIES
This data is the basis for the graphs of bacteria shown in
Figures 37 and 38.
171
-------
Table E-l. Total Coliform Results From Tank Tests Without Screening Using Cl2'
Sample
Cl2 Dosage
(mg/1) " 0
Composition Contact
time (sec) 0
Overflow
Overflow
+
Creek
Overflow
+
Creek
+
Lake
Time of
Sample
Before
Screen
After
Screen
After C12
Initial
20 min
40 min
60 min
Initial
15 min
1 hr
4 hr
12 hr
24 hr
48 hr
72 hr
3,100,000
2,400,000
-
1,200,000
1,480,000
990,000
1,760,000
117,000
34,300
27,000
30,200
13,700
1,120
110
10
25
30
3,100,100
2,400,000
2,900
18,600
1,100
2,800
5,500
820
250
10
10
0
11
5
4
25
60
3,100,000
2,400,000
51,400
29,800
330
130
660
495
240
10
4
22
60
185
8
Creek
Control
-
-
8,200
1,160
2,300
4,400
744
690
400
470
250
365
44
24
Lake
Control
-
-
-
-
-
-
484
594
270
22
56
88
16
4
a all bacterial data represent counts/100 ml
-------
Table E-2. Fecal Coliform Results From Tank Tests Without Screening Using
OJ
Sample
Cl2 Dosage
(mg/1)
0
25
25
Composition Contact
Overflow
Overflow
+
Creek
Overflow
+
Creek
+
Lake
time (sec)
Time of
Sample
Before
Screen
After
Screen
After C12
Initial
20 min
40 min
60 min
Initial
15 min
1 hr
4 hr
12 hr
24 hr
48 hr
72 hr
0
630,000
500,000
539,000
270,400
302,000
390,000
280,000
18,700
11,200
5,390
5,890
2,770
132
0
0
30
630,000
500,000
69,000
35,400
440
910
110
73
0
0
0
0
0
0
0
60
630,000
500,000
330
1,065
88
120
150
76
25
0
0
0
0
0
0
Creek
Control
-
-
-
1,800
440
1,600
550
103
71
66
135
11
0
0
0
Lake
Control
-
-
-
-
-
-
-
71
22
16
5
16
5
0
0
a all bacterial data represent counts/100 ml
-------
Table E-3. Fecal Strep Results From Tank Tests Without Screening Using
Sample
Cl2 Dosage
(mg/1)
0
25
25
Composition Contact
Overflow
Overflow
+
Creek
Overflow
+
Creek
+
Lake
time (sec)
Time of
Sample
Before
Screen
After
Screen
After Cl2
Initial
20 min
40 min
60 min
Initial
15 min
1 hr
4 hr
12 hr
24 hr
48 hr
72 hr
0
161,000
152,000
154,000
76,000
51,700
75,900
89,000
5,940
4,800
3,200
2,400
1,180
115
0
0
30
161,000
152,000
1,920
1,015
550
340
330
36
20
2
0
0
0
0
0
60
161,000
152,000
1,160
635
55
33
22
16
11
0
0
0
3
0
0
Creek
Control
-
-
-
110
660
110
220
29
15
11
0
0
5
5
0
Lake
Control
-
-
-
-
-
-
-
15
0
0
0
0
0
0
8
a all bacterial data represent counts/100 ml
-------
Table E-4. Total Coliform Results From Tank Tests With A 23 Micron Screen Using
Sample
Cl2 Dosage
(mg/1)
0
25
25
Composition Contact
Overflow
Overflow
+
Creek
Overflow
+
Creek
+
Lake
time (sec)
Time of
Sample
Before
Screen
After
Screen
After Cl2
Initial
20 min
40 min
60 min
Initial
15 min
1 hr
4 hr
12 hr
24 hr
48 hr
72 hr
0
750,000
880,000
860,000
431,000
390,000
620,000
920,000
61,00
23,00
18,400
18,700
3,400
1,200
1,023
52
30
750,000
880,000
1,100
1,450
1,360
17,500
0
10
0
0
0
8
48
260
150
60
750,000
880,000
250
1,025
350
0
0
10
0
0
0
0
0
0
0
Creek
Control
-
-
-
1,800
550
2,200
1,370
101
170
236
85
12
8
16
16
Lake
Control
-
-
-
—
—
-
-
11
11
22
16
16
16
8
12
a all bacterial data represent counts/100 ml
-------
Table E-5. Fecal Strep Results From Tank Tests With A 23 Micron Screen Using
CTl
Sample
Cl2 Dosage
(mg/1)
0
25
25
Composition Contact
Overflow
Overflow
+
Creek
Overflow
+
Creek
+
Lake
time (sec)
Time of
Sample
Before
Screen
After
Screen
After C12
Initial
20 min
40 min
60 min
Initial
15 min
1 hr
4 hr
12 hr
24 hr
48 hr
72 hr
0
93,000
77,000
84,000
42,000
60,000
58,000
47,000
3,140
43,000
14,000
1,100
110
22
0
6
30
93,000
77,000
490
330
66
120
0
4
0
0
0
0
0
0
0
60
93,000
77,000
330
250
25
0
0
4
0
0
0
0
0
16
0
Creek
Control
-
-
-
170
170
230
130
13
11
0
8
4
0
8
0
Lake
Control
-
-
-
-
-
-
-
4
0
0
4
0
0
0
0
-------
Table E-6. Total Coliform Results From Tank Tests Without Screening Using C102'
Sample
C102 Dosage
(mg/1) 0
Composition Contact
time (sec) 0
25
30
25
60
Creek
Control
Lake
Control
Time of
Sample
Overflow
Before
Screen
After
Screen
3,900,000
6,700,000
After C102 6,300,000
Overflow
+
Creek
Overflow
+
Creek
+
Lake
Initial
20 rain
40 min
60 min
Initial
15 min
1 hr
4 hr
12 hr
24 hr
48 hr
72 hr
3,150,000
4,200,000
3,300,000
1,760,000
117,500
94,000
91,000
30,000
4,900
1,490
182
504
3,900,000
6,700,000
22,000
12,850
5,700
880
1,300
498
300
220
184
233
74
132
25
3,900,000
6,700,000
2,200
2,850
660
280
300
431
180
204
114
92
88
26
33
-
-
3,700
2,400
110
350
418
350
420
200
57
67
78
12
-
-
-
-
-
-
440
300
470
376
252
127
132
148
a all bacterial data represent counts/100 ml
-------
Table E-7. Fecal Strep Results From Tank Tests Without Screening Using Cl02a
00
Sample
C1C>2 Dosage
Cmg/1)
0
25
25
Composition Contact
Overflow
Overflow
+
Creek
Overflow
+
Creek
+
Lake
time (sec)
Time of
Sample
Before
Screen
After
Screen
After .C10_2_
Initial
20 min
40 min
60 min
Initial
15 min
1 hr
4 hr
12 hr
24 hr
48 hr
72 hr
0
172,000
146,000
160,000
81,850
102,000
82,000
79,000
5,270
36,000
26,000
1,290
360
60
8
4
30
172,000
146,000
1,500
1,245
270
44
44
3
0
0
0
0
0
0
0
60
172,000
146,000
280
635
92
30
29
2
0
0
0
0
0
0
0
Creek
Control
-
-
-
990
130
126
88
6
24
8
12
0
0
0
0
Lake
Control
-
-
-
-
-
-
-
440
300
470
376
252
127
132
148
a all bacterial data represent counts/100 ml
-------
Table E-8. Total Coliform Results From Tank Tests With A 23 Micron Screen Using C102a
Sample
Composition
Overflow
Overflow
+
Creek
Overflow
+
Creek
+
Lake
C102 Dosage
(mg/1)
Contact
time (sec)
Time of
Sample
Before
Screen
After
Screen
After CIO?
Initial
20 min
40 min
60 min
Initial
15 min
1 hr
4 hr
12 hr
24 hr
48 hr
72 hr
0
25
25
Creek
0
12,100
1,800
3,000
1,503
1,900
680
690
50
49
27
38
4
1
,000
,000
,000
,200
,000
,000
,000
,750
,000
,000
,000
,400
,960
550
170
30
12,000
1,800
5
5
2
1
1
4
2
4
1
,000
,000
,500
,950
,000
,560
,230
,832
,700
,800
,500
850
50
132
--
60
12,100
1,800
3
5
4
5
9
4
Control
,000
,000
,900
,150
530
550
390
,776
,200
,500
,500
599
250
170
150
6
7
6
4
b
5
4
2
-
-
-
,400
,100
,000
,440
,420
,600
,700
,400
700
55
88
66
Lake
Control
-
-
-
-
-
-
-
5,100
4,900
6,200
3,600
2,260
270
160
88
a all bacterial data represent counts/100 ml
-------
Table E-9. Fecal Strep Results From Tank Tests With A 23 Micron Screen Using Cl02a
00
o
Sample
C102 Dosage
(mg/1)
0
25
25
Composition Contact
Overflow
Overflow
+
Creek
Overflow
+
Creek
+
Lake
time (sec)
Time of
Sample
Before
Screen
After
Screen
After C102
Initial
20 min
40 min
60 min
Initial
15 min
1 hr
4 hr
12 hr
24 hr
48 hr
72
0
111,000
70,000
80,000
40,195
37,000
36,000
38,000
2,610
3,300
2,700
730
75
20
0
0
30
111,000
70,000
770
580
110
57
92
83
22
39
36
4
0
0
-
60
111,000
70,000
, 420
455
22
8
20
78
134
24
20
0
4
0
0
Creek
Control
-
-
-
390
- 290
310
206
91
57
52
44
8
0
0
0
Lake
Control
-
-
-
-
-
—
-
83
79
76
35
8
0
0
0
a all bacterial data represent counts/100 ml
-------
1. REPORT NO.
TECHNICAL REPORT DATA .
(Please read Infractions on the reverse before completing)
' 13. RECIPIENT'S ACCESSION-NO.
EPA-670/2-75-021
2.
4. TITLE ANDSUBTITLE
BENCH-SCALE HIGH-RATE DISINFECTION OF
COMBINED SEWER OVERFLOWS; With Chlorine
and Chlorine Dioxide
5. REPORT DATE .
April 1975; Issuing Date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Peter E. Moffa, Edwin C. Tifft, Jr.,
Steven L. Richardson, and James E. Smith
8. PERFORMING ORGANIZATION
9. PERFORMING ORG "kNIZATION NAME AND ADDRESS
O'Brien & Gere Engineers, Inc.
1304 Buckley Road
Syracuse, New York 13201
10. PROGRAM ELEMENT NO.
1BB034; ROAP 21-ASY; Task 124
11. cto^l^WC^/GRANT NO.
S-802400 (11020 HFR)
12. SPONSORING AGENCY NAME AND ADDRESS
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Interim, Nov. 71-Mar. 73
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
Division of Drainage and Sanitation
Joint Sponsorship with Department of Public Works
County of Onondago, New York
16. ABSTRACT
A bench-scale study of high-rate disinfection of combined sewer over-
flows with chlorine and chlorine dioxide was performed to aid in the
design and operation of full-scale prototype treatment facilities.
Four logarithm reductions in three inidicator bacteria and several
common viruses were obtained with 25 mg/1 chlorine or 12 mg/1 chlorine
dioxide in two-minutes contact time. Sequential addition of disinfec-
tants enhanced the process such that only eight mg/1 of chlorine fol-
lowed in 15 to 30 seconds by two mg/1 chlorine dioxide were necessary
to obtain similar reductions. The removal of suspended solids by
microscreening through a 23 micron aperture had little effect on dis-
infection efficiency. Disinfection increased slightly with increased
temperature, and a study of the receiving waters indicated no bacterial
or viral aftergrowth. Adenosine triphosphate (ATP) was found to be a
possible alternative to the bacterial indicators of disinfection
efficiency and microbial contamination. Electron spin resonance (esr)
was used as a primary standard method for quantitative measurement of
chlorine dioxide residuals.
Bibliography, 84 references
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Urban areas, Runoff,
Sewage, Overflows,
Tests, *Screenings,
*Disinfection, Bacteri-
cides, Combined sewers,
Chlorine
b.IDENTIFIERS/OPEN ENDED TERMS
*High-rate treatment, Combined
sewer overflows, Suspended
solids removal, Storm runoff,
*Chlorine dioxide, Wastewater
treatment, Laboratory tests,
Viricides, County of Onondago
(New York)
c. COSATI Field/Group
13B
3. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
!1 . NO. OF PAGES
193
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
181
U. S. GOVERNMENT PRINTING OFFICE: 1975-657-592/5360 Region No. 5-I I
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