EPA-600/2-75-060
December 1975
ULTRAVIOLET DISINFECTION OF ACTIVATED SLUDGE
EFFLUENT DISCHARGING TO SHELLFISH WATERS
by
J. A. Roeber and F. M. Hoot
Clow Corporation
Florence, Kentucky 41042
for
THE TOWN OF ST. MICHAELS
ST. MICHAELS, MARYLAND 21663
Project No. WPRD 139-01-68
Project Officer
Cecil W. Chambers
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental
Research Laboratory, U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the
contents necessarily reflect the views and 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 Municipal Environ-
mental Research Laboratory contributes to this multidisciplinary focus
through programs engaged in
• studies on the effects of environmental contaminants on the
biosphere, and
• a search for ways to prevent contamination and to recycle
valuable resources.
This report describes a unique disinfection process applied to a
municipal wastewater effluent to protect a shellfish area.
m
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ABSTRACT
A tertiary treatment plant and an ultraviolet disinfection chamber
were installed following an activated sludge plant at the municipal
sewage treatment plant in St. Michaels, Maryland.
The multiple-tube fermentation technique was used to determine the
total coliform MPN Index after varying exposures to ultraviolet rad-
iation. Batch tests were sampled at various intervals under constant
radiation, and flow-through tests were sampled before and after under-
going radiation.
The standard to be met was an MPN of not more than 70 per 100 ml.
In flow-through tests this was usually achieved with a flow not in
excess of 40,000 gallons per day, with a turbidity of less than 11
JTU, using sixteen germicidal 36 watt ultraviolet lamps; an energy
application of 0.35 KWH/1000 gallons.
The absorption of ultraviolet radiation, as measured by the absorption
coefficient, was much more dependent on COD than on turbidity, indicating
the appearance of the effluent is not the best criterion for estimating
the rate of U.V. absorption, or the initial intensity required to pene-
trate to the bottom of the U.V. treatment unit.
Both Coliforms and Bacteriophage multiplied when exposed to visible
light after ultraviolet radiation treatment.
Coliform inactivation followed first order kinetics until 99.99% in-
activation occurred; followed by a tailing-off curve. Bacteriophage
followed first order kinetics up to the maximum available ultraviolet
rate.
This report by Clow Corporation for City of St. Michaels, Maryland, was
submitted in fulfillment of Project Number WPRD 139-01-68 under the
partial sponsorship of the Wastewater Research Division, Municipal
Environmental Research Laboratory (formerly the Advanced Waste Treatment
Research Laboratory, National Environmental Research Center), U.S.
Environmental Protection Agency. Work was completed December 21, 1972.
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CONTENTS
Abstract iv
List of Figures vi
List of Tables vii
Acknowledgments viii
SECTIONS:
I Conclusions 1
II Recommendations 2
III Introduction 3
IV Activated Sludge Plant 6
V Tertiary Treatment Unit 12
VI Conduct of Tests 16
VII Operating Problems 19
VIII Test Results and Discussion
A. Static or Batch Tests 22
B. Dynamic Tests 26
C. U. V. Absorption 26
D. Mixing in U-V Chamber 32
E. pH Value of Sewage 34
F. Bacteria Density 34
G. Shielding of Bacteria by Suspended Matter 36
H. Photoreactivation of Bacteria 39
I. Bacteriophage Inactivation 39
J. Bacteriophage Photoreactivation 46
IX References 50
X Glossary 51
XI Appendices 52
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FIGURES
NO. PAGE
1 FLOW DIAGRAM OF SPLIT TREATMENT PROCESS AND 7
TERTIARY PLANT
2 DISINFECTION CHAMBER 13
3 COLIFORM SURVIVAL CURVES - STATIC TESTS 23
4 COLIFORM SURVIVAL CURVES vs. EXPOSURE TIME, 25
STATIC TESTS
5 COLIFORM MPN vs. TURBIDITY FOR 76 DYNAMIC TESTS 27
6 U-V INTENSITY vs. TURBIDITY, DYNAMIC TESTS 28
7 REGRESSION OF ABSORPTION ON COD 30
8 SURVIVAL RATIO VARIATION WITH pH 35
9 COLIFORM SURVIVAL IN LIGHT AND DARK 41
10 GRAPH OF COLIFORM SURVIVAL IN LIGHT AND DARK 42
11 INACTIVATION CURVE FOR F2 PHAGE 45
12 SAMPLING PLAN FOR PHOTOREACTIVATION TEST 47
VI
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TABLES
No. Page
1 Flow & BOD,- for Comparison of Treatment Processes 1ft
2 Pounds of BOD5 in Effluent Before Chlorination 11
3 Data from static tests 24
4 U-V Absorption Coefficient, COD, and Turbidity Data 29
5 Regression Analysis: UV Absorption, COD, and Turbudity 31
6 Effect of Flow Pattern by Baffle Changes 33
7 Effect of Bacteria Density on Survival 37
8 Coliform Determination After Different Mixing Methods 38
9 Effect of Photoreactivation 40
10 Effect of Photoreactivation at High U-V Exposure 43
11 Fp Phage Inactivation 44
12 F2 Phase Photoreactivation 48
13 Photoreactivation of F2 Phage With Added K-37 Host Cells 49
VII
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ACKNOWLEDGEMENTS
The support of the Town Council of St. Michaels and the Maryland State
Board of Health is acknowledged with sincere thanks.
The administrative, technical, professional, fiscal and legal details of
the project were handled by the Clow Corporation Waste Treatment Divis-
ion.
The original project director was Emerson E. Longrell of St. Michaels;
however, his untimely death occurred 2 weeks after the start of the
project.
The original Assistant Project Director was E. F. Bradley of Clow Corp-
oration. He resigned 2 months after startup.
John A. Roeber, of Clow Corporation was the Project Engineer during the
entire project. He also served as Acting Project Director.
Mrs. Helen Plummer of St. Michaels was the Project Finance Officer.
Frank Hoot was the Resident Engineer.
The support of the project by the Environmental Protection Agency and
the help provided by Harold Snyder, Richard Brenner and Cecil W. Chambers,
the Grant Project Officer is acknowledged with sincere thanks.
vm
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SECTION I
CONCLUSIONS
1. The ultra-violet disinfection process should be used following
well-controlled activated sludge plants. Ultraviolet disinfection
of effluents containing high solids and high organics was not
possible at the U-V exposure levels availablei
2. In static (batch) tests, the average ultraviolet dose in microwatt
seconds per square centimeter to produce an effluent with a coli-
form MPN Index less than 70 was about 25,000, with an exposure time
of 120 seconds.
3. In dynamic (flow-through) tests with 130 seconds exposure, the
coliform MPN was usually below 70 when the turbidity was below
11 JTU and above 70 with higher turbidity.
4. The absorption of U-V, and therefore, the initial intensity needed
to penetrate the flow-through cell, was much more dependent on the
COD of the influent than on the turbidity. A continuous process
should be controlled by both an organic detector and a turbidity
meter.
5. Samples initially higher in coliforms, when subjected to the same
ultra-violet dosage had higher numbers of surviving coliforms than
did samples with lower initial coliforms.
6. Exposure of samples to visible light after a sublethal dose of ultra-
violet exposure favors the continued multiplication of bacteria, while
a decline in density was noted in a sample kept in the dark.
7. Bacteriophage inactivation by ultra-violet radiation followed first
order kinetics.
8. Bacteriophage subjected to a sub-lethal dose of ultraviolet radiation
and then exposed to visible light continued to multiply.
9. Sixteen (16) 36-watt ultraviolet germicidal lamps were shown to re-
duce the coliform MPN of a good activated sludge effluent to below
70 at a flow rate of 40,000 gpd, at an energy consumption of .35
Kilowatt hours per thousand gallons.
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SECTION II
RECOMMENDATIONS
This project was very limited in funds for virus determinations, so
that by the time a modest program was outlined the activated sludge
plant was no longer producing an acceptable effluent. It is recomm-
ended that the viricidal capability of ultraviolet radiation be
compared with chlorination.
Further work should be done with an activated sludge plant that pro-
duces a consistently good effluent to determine the day-to-day bacter-
icidal efficiency of ultra-violet radiation. This project was limited
to 10 coliform determinations twice a week by space, equipment, and
manpower.
The amount of ultra-violet should be increased an order of magnitude
to determine if photoreactivation can be overcome. Higher wattage U-V
sources should be used so the flow velocity is sufficient to prevent
solids deposition. The ability of a stronger U-V source to handle
programmed plant upsets or the inevitable accidental ones should be
investigated. The energy requirement of this project was relatively
modest at 0.35 KWH/1000 gallons, so that higher U-V doses would be
practical. Higher strength ultraviolet lamps are available, but their
efficiency in converting electrical energy to ultraviolet energy is low.
The demonstration that ultraviolet radiation of effluents is practical
could possibly hasten the development of a high wattage high efficiency
ultraviolet source. This would bring down the electrical operating
cost as well as the capital cost as the result of smaller structural
requirements.
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SECTION III
INTRODUCTION
The effluent from every waste treatment plant which has been constructed
in shellfish areas up to the present time has adversely affected shell-
fish, and the receiving waters in the vicinity of effluent lines have
all been restricted to the harvesting of shellfish. The size of the
restriction has depended on many factors; such as, effectiveness of plant
operation, degree of treatment provided, size of plant and reliability
of the treatment process. The effluent from a well-operated activated
sludge treatment plant discharging 100,000 gallons per day can be
responsible for the restriction of hundreds of acres of surface water.
Public Health Service Bulletin #1500 entitled "National Register of
Shellfish Areas"* shows that approximately 2,000,000 acres of shellfish
growing water out of a total of 10,000,000 acres are presently closed to
the harvesting of shellfish. By far, the greatest portion of this is
due to the effects of effluents from waste treatment plants.
The grant was approved May 10, 1968. The equipment installation was
completed and the plant startup was on Nov. 26, 1968. Operation con-
tinued to the end of the original 18-month period plus a six-month and
a two-month extension.
The community of St. Michaels, Maryland, which had an existing activated
sludge plant, was directly concerned over the loss of shellfish harvest-
ing, value of riparian real estate, and the effect on tourist business.
They applied for and received an EPA Research Grant (WPRD-139-01-68)
for 75% of the cost of installing and operating for 18 months a "Controlled
Treatment System" manufactured by Yeomans Division of Clow Corporation.
12J$ of the funds were supplied by Clow Corporation and 12%% by the State
of Maryland. The Controlled Treatment System is based on U. S. Patent
#3,459,303.
Five factors important in the plant design, which is to be applied to an
activated sludge plant effluent are:
(1) The effluent must have a very low bacterial count; i.e., not
greater than an MPN of 70 coliforms per 100 ml.
(2) There should be a significant reduction in the number of
viruses below that which is now found in a plant effluent.
(3) The effluent must contain no harmful chemicals.
(4) There must be no by-passing of raw or partially treated wastes
to the receiving waters.
(5) All of the above criteria must be maintained continuously if
the receiving waters are to be opened to the harvesting of
shellfish.
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Effluent from the activated sludge plant is given a tertiary chemical
treatment if necessary and then flows under ultra-violet lights through
3-inch deep troughs. The amount of U-V is measured at the bottom of the
trough. If the U. V. is below a preset point which is known to give
satisfactory disinfection, the effluent is automatically discharged to
a holding lagoon instead of to the shellfish receiving water. The mal-
function is corrected, and the lagoon-stored effluent is then pumped
back through the plant for adequate treatment. Continuous indicating
and recording flow meters, ultra-violet meters and turbidity meters are
used. Either high turbidity or low U-V will signal the operator at
the same time the improperly treated effluent is automatically bypassed
to the holding lagoon.
All chemical and bacteriological testing was done at the sewage treatment
plant site in a house trailer fitted as a laboratory. Ultraviolet radia-
tion was used as a means of disinfection and the determination of the
coliform MPN was the primary evaluation test.
The bactericidal, viricidal and fungicidal properties of ultraviolet
(U-V) radiation are well known. The germicidal U-V lamp is a low
pressure mercury lamp designed so that more than half of the input energy
is generated by the mercury vapor at its predominant wavelength of 2537
Angstroms (A°), as the bactericidal effect peaks between 25QO and 2700 A°.
In most disinfection processes, the rate of kill is expressed by
^ = -KN
dt
where 4v-= rate of kill
K = rate constant
N = number of living micro-organisms
N0 = number of living organisms at time zero
N.
If Log N is plotted against time, a straight line should be obtained with
a slope K which is proportional to radiation intensity.
The intensity of radiation is reduced as it passes through an absorbing
medium. It is recommended the depth of liquid in the irradiation chamber
should be such that not more than 90% of the U-V should be absorbed by
the time the UV reaches the bottom of the chamber.
The reduction in intensity is expressed by
I = I0e - Kd
where I = radiation intensity
*o= initial radiation intensity
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e = base of natural logarithms
K = absorption coefficient
d = distance between points where the intensities are IQ and I
The average intensity thru the chamber is
1-e -Kd
lave = IQ ( Ra )
The U. S. Public Health Service policy statement of April 1, 1966 on
the "Use of Ultraviolet Process for Disinfection of Water" was used as a
guide in sizing the disinfection chamber. See Appendix A.
The Controlled Treatment system was designed to process a good activated
sludge effluent. Changes were made until June, 1969 to improve the
operation of the activated sludge to produce a good quality secondary
effluent, i.e. about 20 mg/1 BOD instead of the 150 mg/1 average that
was produced thru April, 1969.
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SECTION IV
ACTIVATED SLUDGE PLANT
The ultraviolet disinfection experiments were conducted on the effluent
from an existing activated sludge plant in the town of St. Michaels,
Maryland on the Miles River.
The activated sludge plant receives the domestic sewage from about 1500
persons in the town. Sewage is pumped to the plant from two pumping
stations located at terminal points in the sewage collection system.
Both pumping stations discharge to a common force main which terminates
at the sewage plant.
The sewage plant was constructed in 1953 to treat 100,000 gallons of
sewage per day. Due to infiltration and population growth, daily flow
varied greatly and the plant was hydraulically overloaded. During
the period from June 1969 to May 9, 1970, when these experiments were
carried out the lowest daily flow recorded was 85,000 gallons and
the highest daily flow was estimated at 383,000 gallons. The average
daily flow during this period was 143,000 gallons.
Due to the variation in flow and recirculation of sewage to the primary
settling tank, detention time in the 16,950 gallon tank varied. Settled
material from the primary settling tank is mechanically scraped to hoppers
and then pumped to an unheated anaerobic digester. The settled effluent
from the primary tank was split to flow three ways.
The tertiary treatment unit was operated on a pilot plant basis. Only
part of the sewage biologically treated in the secondary plant was
pumped to the tertiary treatment unit. A flow diagram showing the re-
lation of the secondary plant and the tertiary unit with the division of
flow is shown in Figure 1.
During the course of the experiments, the secondary treatment plant
was operated on a split treatment basis. Implementation of the split
treatment process was necessary due to the hydraulic overload on the
plant and the deteriorated condition of the secondary settling tank.
These conditions prevented production of a good quality effluent. The
split treatment process enabled the production on part of the sewage
of a secondary effluent that was consistent with effluent that could
be produced from a satisfactory operating activated sludge plant.
Part of the primary effluent was diverted to a combined aerator-clarif-
ier unit. Aeration is provided in the outer perimeter of the tank
with a circular secondary settling tank in the center of the tank. Flow
to the unit was controlled by an orifice installed in the primary tank
effluent trough. The orifice was adjusted to pass 105,000 gallons of
sewage per day. Capacity of the aeration part of the tank is 49,700
gallons. Aeration originally was accomplished by a surface aerator
which spilled sewage over a fixed plate on top of the secondary clar-
ifier. The rated capacity of the surface aerator would "turn over"
the sewage in the aerator every ten minutes. The draft tube from
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Row sewage influtnt
supornatent
S
£
/
1 average \ I
43,000gpd X '
U head box x
pf tow recorder
TERTIARY TREATMENT
UNIT
8 outfall to
Miles river
FIG. I
FLOW DIAGRAM OF SPLIT TREATMENT PROCESS
AND TERTIARY PLANT
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which the surface aerator drew sewage from the bottom of the tank ran
through the clarifier. The outer shell of the clarifier tank was badly
pitted and corroded. With the high turnover rate this caused currents
in the secondary clarifier and resulted in poor secondary settling.
To overcome this condition, a new blower was installed and the aeration
tank was fitted with bottom air diffusers. Six air lines were put down
into the tank, each with a horizontal arm equipped with 18 air diffusers..
This arrangement provided good aeartion and did not upset the secondary
clarifier. At the 105,000 gallon per day flow rate, the mixed liquor
solids could be maintained at about 1200 - 1400 mg/1 with a minimum
dissolved oxygen content in the mixed liquor of 1.5 - 2.0 mg/1.
After aeration, the sewage flowed into the 16 foot diameter central
clarifier unit. The upper part of the unit is a cylindrical tank with
a capacity of 8,130 gallons and provided for secondary settling of the
aerated sewage. The bottom of the unit is an inverted cone providing
sludge settling space with a capacity of 780 cubic feet. The apex of
the cone is at the bottom of the tank. An airlift pump drawing at the
bottom of the apex was installed and provided for the return of the
settled sludge to a head box. In the head box the settled sludge could
be returned to the sewage coming into the aerator or wasted to the
primary tank as needed.
Settled effluent from the clarifier was taken off on a five foot diameter
weir and discharged into a trough on the outside of the aerator tank. In
the trough, a flowmeter measured and recorded the flow over a 45°
triangular notch weir.
The final effluent was carried off by an eight inch outfall line which
ran approximately 1,200 feet to a submerged discharge in the Miles River.
Chlorine was injected in the 8" line with contact time provided in the
pipe.
The second part of the primary effluent was diverted to a 100,000 gallon
capacity holding pond on the sewage plant site. The holding pond was
equipped with a time controlled pump which recirculated sewage to the
influent of the primary tank. The sewage diverted to the holding pond
was pumped back to the primary tank at night and during periods of
low flow. By this means a fairly steady flow was maintained in the
primary tank and resulted in a steady flow of sewage to the aerator.
That part of the primary effluent which was not diverted to the aerator
or the holding pond was discharged to the trough on the outside of the
aerator. In the trough the by-passed primary effluent was blended with
the effluent from the aerator-clarifier, chlorinated and discharged to
the river.
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In the original operation of the plant, the flow from the primary tank
was not split. All sewage was biologically treated in the aerator-
el arifier unit. Due to the hydraulic overload and condition of the
secondary clarifier, a poor quality effluent was produced, as determined
by the five day BOD test. To evaluate the effects of the split treat-
ment process to the normal operation, a comparison was made on cal-
culated pounds of BOD5 in the effluent produced by the two treatment
processes. The comparison was based on total flow and average BODg
determinations made during periods when the two processes were in
operation. The split treatment process was operated in conjunction
with the tertiary unit and about 43,000 gallons of sewage received
additional treatment. The effect of the additional treatment was figured
in the split treatment process. This comparison is shown in Tables
1 & 2.
for the period when all sewage was biologically treated in the aeration
tank the calculated average pounds of BODc in the plant effluent was
185.
For the split treatment comparison period the calculated daily average
pounds of 8005 was 66. Based on this comparison the split treatment
process removed 64% more of the BODs than did the normal plant operation
under overloaded conditions.
After chlorination, no sampling point was accessible either for full
treatment or split treatment; therefore, the actual BOD entering the
receiving water could be expected to be less than before chlorination
for both treatment modes; however, this BOD was not measured.
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TABLE 2
POUNDS OF BOD5 IN EFFLUENT BEFORE CHLORINATION
NORMAL TREATMENT
Pounds BODR
Period per month
February 1969 3.633 x 8.34 x 158 = 4787
March 1969 4.899 x 8.34 x 143 = 5843
April 1969 4.222 x 8.34 x 167 = 5880
Daily average pounds BODr in plant effluent = 185
SPLIT TREATMENT
June 1969 (15 days)
Total Flow 2,069,000
Secondary Effluent (15 x 62,000) 930,000 .93 x 8.34 x 22 = 171
Tertiary Effluent (15 x 43,000) 645,000 .645 x 8.34 x 17 = 91
Primary Effluent 494,000 .494 x 8.34 x206 = 849
Total Pounds BOD,- in Combined Plant Effluent 1111
b
July 1969
Total Flow 4,102,600
Secondary Effluent (31 x 62,000) 1,922,000 1.922 x 8.34 x 19 = 305
Tertiary Effluent (31 x 43,000) 1,333,000 1.333 x 8.34 x 12 = 133
Primary Effluent 847,600 .8476 x 8.34 x209 =1477
Total Pounds BOD5 in Combined Plant Effluent 1915
Daily Average Pounds BOD5 in Plant Effluent = 66
11
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SECTION V
TERTIARY TREATMENT UNIT
The tertiary unit consisted of a settling tank, an ultraviolet disin-
fection chamber, and controls to monitor certain parameters of the
effluent. The unit was manufactured as an advanced wastewater control
system. The unit was intended for use in areas where it was desirable
to have continuous control and monitoring of the bacteriological
quality of the discharged effluent. The bacteriological quality was to
be gauged by the measure of turbidity and ultraviolet absorption in the
effluent. A description of the process as designed is described else-
where. 2
The tertiary treatment unit was operated on a pilot plant basis in
that of the 105,000 gallons of sewage per day biologically treated in
the secondary plant, approximately 43,000 gallons per day were pumped to
the unit. A pump was installed with the section in the secondary clari-
fier and discharged to a head box. The sewage flow in the head box could
be adjusted, permitting regulation of flow to the tertiary unit. The
unit was operated on a 24-hour basis.
Discharge from the head box was directed to a 265 gallon capacity chemi-
cal mix tank in the center of the tertiary settling unit. Calculation
of flow in the tertiary unit was based on the time to fill the chemical
mix tank. A chemical feed pump with discharge in the chemical mix tank
was available to feed settling aids as needed. Settling aids were
mixed in the chemical mix tank by a variable speed paddle mixer.
The overflow from the chemical mix tank was directed downward by a
cylindrical shell around the tank. The settled effluent was drawn
upward and off the tank by surface weirs located on each side of
the tank. The vertical settling tank was constructed in the shape of
an inverted pyramid and had a capacity of 4,760 gallons. The bottom
of the tank was fitted with a sludge drawoff line.
Dye tests indicated that the average detention time in the tertiary
tank was about 70% of theoretical detention time. At a flow rate
of 36.7 gpm an average detention time of 130 minutes was indicated;
however, by dye test, the average detention time was 92 minutes.
Settled sewage from the tertiary settling tank was directed to the
ultraviolet disinfection chamber.
Sewage flowing in the disinfection chamber was subjected to ultra-
violet irradiation from lamps mounted over the surface of the sewage.
The chamber was fitted with meters to monitor the ultraviolet intensity
after passing through a layer of the sewage, current to the ultra-
violet lamps and the turbidity of the sewage. A sketch of the chamber
is shown in Figure 2.
12
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Row baffle
Ultraviolet lampsx
INLET
Photoelectric sensing
device
FIG. 2
DISINFECTION CHAMBER
13
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The ultraviolet chamber was 12'-6" long by 2'-8" wide with a liquid
depth of slightly less than three inches. The chamber was divided
into four parallel rectangular channels which directed the flow the
length of the chamber. In each chamber, baffles IV high were placed
on fifteen inch centers. The channels and weirs were painted with
aluminum paint.
Liquid capacity of the chamber is 60.8 gallons. Liquid depth in the
chamber was maintained by an overflow trough at the effluent end.
Four hinged hoods covered the chamber and were arranged end to end.
Each hood was fitted with a parabolic Alzak reflector and four
G36T-6 36" long ultraviolet germicidal lamps. The lamps were
nominally rated at 36 watts with an average ultraviolet output at
2537 A° of 10.4 watts through the life of the lamp. Under normal con-
ditions the lamp life is approximately 7500 hours. The ultraviolet
lamps were arranged with the length of the tube parallel to the sewage
flow. With the hoods down, the lamps were over the center of the four
channels. The center of each lamp was 2-5/8" above the liquid surface.
At the effluent end of the chamber in the bottom center of each channel
a quartz window was fitted. Beneath each quartz window a photo sensor
was installed. The photo sensor measured the residual ultraviolet
intensity with readout in microamperes on a photometer located in a
control panel outside the chamber. The meter was equipped with a low
level indicator. Readings below a predetermined value carried a signal
to be sent to a relay in the control panel. A recorder provided a
continuous record of ultraviolet intensity.
One channel was equipped with a quartz window extended under the liquid
surface, enabling ultraviolet intensity readings to be made at this
location. The distance between the extended window and the low quartz
window was 2.81 inches. With provision to read the ultraviolet intensity
at two levels in the liquid the ultraviolet absorption in the sewage
could be determined.
At the effluent end of the disinfection chamber, a continuous sample of
the irradiated effluent was piped to a continuous reading and recording
surface scatter turbidimeter. The turbidity meter was equipped with a
high level alarm, which when the turbidity exceeded a predetermined
value sent a signal to a relay in the control panel.
Low level indications from the ultraviolet meter and/or high turbidity
signals transmitted to the control panel served to operate a solenoid
operated gate. If de-energized, the gate was dropped and diverted the
effluent to the holding pond. Sewage diverted to the holding pond was
recirculated to the primary clarifier, during periods of low flow.
14
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Sewage was discharged from the unit if it had been subjected to a pre-
determined minimum ultraviolet exposure and if the turbidity level in
the sewage did not exceed a predetermined value. The effluent from
the pilot tertiary unit was mixed with the chlorinated blend of primary
and secondary effluent, and the total mixture was discharged to the
Miles River.
A current meter installed in the ultraviolet lamp circuit indicated the
number of lamps burning. Each lamp drew about 0.5 amperes, and with
16 lamps in operation the meter read 9.0. A drop in the meter indicated
the number of lamps not drawing current and diverted the effluent to
the holding pond. This meter only indicated if a lamp was drawing
current and did not give information on ultraviolet output. The lamps
were periodically checked with the photo sensor to determine if they
were producing 2537 A° Angstrom ultraviolet. Operating instructions
for the instrument and safety control relay box are attached as
Appendix B.
15
-------
SECTION VI
CONDUCT OF TESTS
Experiments with the ultraviolet irradiation of sewage effluent were
conducted under static batch conditions and under actual flow-through
conditions of operation in the ultraviolet disinfection chamber. The
conditions of exposure in the static tests were made to approximate
the conditions of exposure in the chamber.
The static tests were conducted with a sample of sewage in a rectangular
pan under one of the hoods. The 36" long pan was placed in one of the
troughs. The pan was fitted with a center divider and IV high baffles.
The pan held about 10 liters at a depth of three inches. An electrically
driven paddle circulated the sewage around in the pan. Exposure time
to ultraviolet radiation was controlled by the switch to the ultraviolet
lamp circuit. Samples of the irradiated sewage could be withdrawn at
appropriate time intervals.
Dynamic tests were made under actual flow and exposure conditions in
the ultraviolet disinfection chamber. Exposure time of the sewage could
be accomplished in two ways. The flow in the tertiary unit could be
varied, thus varying the exposure time, or the number of lamps could be
reduced. The lamps under the hoods could be removed to reduce the
exposure time by one quarter, one half, or three quarters as desired.
Irradiated samples that were checked for light reactivation were put
in clean, sterile, saran-covered pans and thus exposed to the natural
light. Samples checked for dark exposure were similarly treated, but
covered and sealed under a dark box.
All samples collected for bacteriological and chemical examination were
collected in sterile bottles and analyzed as soon as possible. While
working with the collected samples, they were kept in a dark refrigerator.
Tests were performed in accordance with Standard Methods.3
Coliforms Estimation of coliform group density was made by the multiple
fermentation tube technique. Lauryl sulfate broth was used in the pre-
sumptive test and positive tubes were confirmed in 2% brilliant green
bile broth. The procedures were carried out as prescribed with one ex-
ception.
Transfer from positive presumptive tubes to confirmed tubes were made
with slender sterile wooden sticks, instead of sterile metal 3mm loops.
From appropriate dilution of the sample, five fermentation tubes were
innoculated. In most cases, more than three dilutions were set up so
the three most valid dilutions could be obtained. The positive tube
findings were expressed as Coliform most probable number index per
100 ml. The index numbers were obtained from appropriate tables.
16
-------
Expression of the coliform MPN index per 100 ml is not a direct count of
the bacteria. The estimate of the density is based on the probability
of obtaining particular results in a series of fermentation tubes, each
innoculated with an appropriate amount of the decimally diluted sample.
Prepared tables give an estimate of the bacteria density with 95% con-
fidence limits based on the results of the fermentation tubes.
It has been indicated that the coliform MPN index of replicate tests
made on sample having a fixed bacteria density are distributed about
the mean density approximately in accordance with a log normal frequency
curve. Based on this, replicate determinations on a sample to determine
coliform density are expressed as a geometric mean.
The use of a geometric mean as the expression of coliform density rules
out the use of tests of significance based on the normal distribution.
Tests of significance between means of coliform density in samples are
based on non-parametric statistical methods. The non-parametric methods
are considered distribution free and can be used when sampling from
non-normal populations.
Bacteriophage. Phage used in experiments were fp RNA bacteria virus.
Cells used to plaque the f£ phage were E. Coli K-37. Assay of bac-
teriophage was performed by the agar layer method. Results of the
assay were recorded as Plaque Forming Units (PFU) per ml.
Biochemical Oxygen Demand (BOD). BOD determinations were made in a
20° C incubator following standard procedures. Results were expressed
as mg/1 of five day BOD.
Chemical Oxygen Demand (COD). COD determinations were made by the
potassium dichromate reflux method following standard procedures.
Results were expressed as mg/1 COD.
Hydrogen Ion. pH determinations were made on a Fisher Accumet Model
210 pH meter. The meter was periodically checked with standard reference
solutions.
Ammonia Nitrogen. Ammonia nitrogen determinations were made by the
direct nesslerization method following standard procedures. Color
measurements were made on a Bausch and Lomb Spectronic 20 colorimeter
at 400 Millimicrons (mu). Results were expressed as mg/1 ammonia
nitrogen.
Nitrate Nitrogen. Nitrate nitrogen determinations were made by the
Brucine method following standard procedures. Color measurements were
made on the Bausch and Lomb Colorimeter at 410 mu. Results were ex-
pressed as mg/1 nitrate nitrogen.
Iron. Iron determinations were made by the 1.10 Phenanthroline method.
Color developed in the sample was read as percent transmittance at
500 mu in the Bausch and Lomb Colorimeter. Transmittance was compared
to a standard curve and the results were recorded as mg/1 iron.
17
-------
Flow. The flow in the tertiary unit was determined by volume discharge
calibration of the pump. Flow was expressed as gallons per minute (gpm),
Turbidity. Turbidity measurements were made on a Hach Continuous Read-
ing Surface Scatter Turbidimeter. The unit was calibrated to read in
Jackson Turbidity Units (JTU) based on a standard Formazin suspension.
The meter was periodically checked at three different values with
standard plates.
Ultraviolet Intensity Measurements. Ultraviolet measurements were
made on an International Light IL 201 ultraviolet-visible threshold
photometer. The photometer operated with a remote vacuum Diode
Photosensor type PT 100. The photosensor was calibrated at 2537 A°
against a low pressure mercury light source from a spectroradiometer.
The spectral response of the photosensor gave a readout in microamperes
on the photometer. Readings from the photometer in microamperes
multiplied by the calibration factor gave the intensity of the 2537 A°
ultraviolet in microwatts per square centimeter (uw/cnr). Calibration
factors for the photosensors were:
1. 122
2. 138
3. 139
4. 147
5. 264
Coagulant aids were available to aid settling of solids in the tertiary
tank. Jar tests conducted on sewage samples indicated that use of a
cationic polymer alone or in combination with a specially prepared
bentonite aided in settling. However, use of the coagulant aids in
actual operation was abandoned due to the overload condition in the
basic plant. Sludge accumulations in the tertiary tank were pumped
to the primary settling tank. The tertiary sludge plus the additional
settling obtained in the primary tank by the addition of the coagulant
aid generated a heavy volume of sludge. The increased sludge required
additional pumping to draw off the primary sludge. This additional
load on an already overloaded digester resulted in a heavy supernatant
return to the primary settling tank. The heavy flow of supernatant
return to the primary tank resulted in high BOD values in the primary
effluent.
18
-------
SECTION VII
OPERATING PROBLEMS
During the course of the experiments every effort was made to operate
the tertiary treatment continuously. There were a number of problems
which upset the process and the continuity of the project. In addition
to hydraulic overload, the mechanical condition of the basic plant and
weather condition were factors.
The problem of hydraulic overload in the secondary plant is indicated
by the average flow of 143,000 gpd, with a range of 85,000 to 375,000
plus, in a plant designed for 100,000 gpd. Most of the hydraulic
overload was attributed to ground and storm water flow. During periods
of rain, flow to the plant increased rapidly.
The combination of high sewage flow and high tide in the Miles River
resulted in an inadequate hydraulic gradient in the 8" outfall line.
During the period the final sewage effluent backed up in the outfall line.
Equipment in the basic plant had been in use for 15 years prior to the
start of the project. During most of the project, the sludge transfer
pump was in unsatisfactory condition and the standby pump could not be
used.
The steel shell of the secondary settling tank was pitted and corroded.
This resulted in short circuits in the secondary settling and did not
permit good secondary settling.
Initiation of the split treatment process relieved the hydraulic over-
load in the aerator and secondary settling tank. Use of the primary
settling tank to recirculate sewage added to the overload in the primary
settling tank.
Temperature was a factor in operation of the plant. The secondary plant
and tertiary plant were constructed above grade and cold weather upset
the biological process. In cold weather little biological action took
place in the digestor and pumping of primary sludge to the digester
resulted in a heavy supernatant return to the primary tank. When sewage
temperature fell below 10°C, heavy bulking of the activated sludge was
experienced. The activated sludge would bulk and continuously purge for
several days.
Flow to the tertiary settling unit was steady and the main problem in
operation resulted from conditions in the secondary plant. The main
problem was bulking of the activated sludge. A Sludge Volume Index
of 1,000 was common. The light material was carried into the tertiary
settling tank. The material was difficult to settle and use of settling
aids created such a volume of sludge that the unit was soon full. Warm
weather rather than cold weather affected the use of the tertiary tank.
19
-------
The tertiary tank was a steel shell set above grade level. Temperature
difference between the steel shell and the sewage in the tank resulted
in gasification in solids settled on the steel shell. Layers of the
settled material would float to the surface and flow thru the U.V.
disinfection chamber. Warm weather also produced heavy slime growth
in the exposed trough of the settling tank. In warm weather, the slime
growth had to be cleaned off daily.
During May, 1969, the split treatment process was started in operation.
By June, 1969, the process was brought up to an operating level. For
the remainder of June, and during July and August the process performed
without interference. On Sept. 5, 1969, the process was voluntarily
shut down due to a controversy over a crab and fish kill in the Miles
River. On September 15, 1969, the process was put back into operation.
Little trouble was experienced in putting the process into full operation.
On Sept. 22, 1969, a quantity of gasoline was dumped into the sewage
collection system. For several days a gasoline odor permeated from the
sewage plant. For two weeks following the gasoline spill the activated
sludge spontaneously bulked and interfered with operation of the tertiary
unit. From this time until Jan. 10, 1970, the operation performed
without upset.
On January 9, 1970, the weather was severely cold and the temperature of
the sewage in the plant dropped below 10°C. With the lower temperature
the activated sludge bulked. During the cold weather the activated
sludge would periodically bulk and continue to purge for several days.
The periodic bulking of the activated sludge continued until
April 27, 1970.
The end of April marked the beginning of a warming trend and the
temperature of the sewage started to increase above 10°C. At this time
the activated sludge bulked again and continuously purged until the
termination of the project on May 9, 1970.
As indicated in Figure 1, settled sewage from the tertiary tank was
directed to the ultraviolet disinfection chamber. From the trough to
the disinfection chamber, the direction of flow was directed at right
angles into the four parallel troughs in the disinfection chamber.
Velocity of sewage flow in the disinfection chamber was low thus
permitting settling of solid material. Capacity of the disinfection
chamber was 60.8 gallons, and at average operating flows of 30 gallons
per minute the velocity in the chamber was .103 ft/sec. With such
a low velocity,sewage mixing was not adequate and even the lightest
suspended material settled in the chamber.
The sewage level in the disinfection chamber was controlled by a long
trough exposed to natural light. Bacteria exposed to ultraviolet and
then exposed to visible light had a tendency to recover from the UV
damage. The open exposure of the irradiated effluent in the trough
would favor photoreactivation of the bacteria.
20
-------
The U. V. lamps were arranged parallel with the sewage flow. An
arrangement whereby the lamps were at right angles to the flow might
be more efficient. The U. V. output of the lamp could only be checked
on four lamps at any one time. To check the other lamps the unit had to
be shut down and the lamps, in turn, put in the end hood and checked
for U. V. output.
During periods of high humidity trouble was encountered with the pin
connection of the U. V. lamps. Each fixture and pin end on the lamp
had to be cleaned and coated with an electrical contact aid. The
ultraviolet disinfection unit was outdoors and low temperature reduced
the U. V. output of the lamp.
In general, the electrical control panel and meters performed well with
the exception of the solenoid operated diversion gate. The electrical
components of the gate were housed in a non-watertight cover.
Corrosion was heavy and the gate required frequent maintenance.
21
-------
SECTION VIII
TEST RESULTS AND DISCUSSION
A. STATIC OR BATCH TESTS
Prior to making tests in the ultraviolet disinfection unit, five
static tests, conducted as previously described, were run. These
tests were intended to:
a) Check on the kinetics of inactivation for coliform bacteria
in sewage effluent when exposed to ultraviolet radiation.
b) Determine the level of turbidity which would interfere with
reduction of the coliform level to the preset index value.
c) Determine other factors which would interfere with the in-
activation of bacteria in sewage effluent.
The data from these tests are given in Appendix C and summarized
in Table 3.
The logarithm of the survival ratio of bacteria plotted against
the dose of ultraviolet radiation purportedly gives a straight line.
For comparison, the survival ratios from the static tests were
plotted in a semi logarithm graph as shown in Figure 3. For the test
results, the following is indicated
a)
b)
c)
a straight line relation does not hold thru the full course of
exposure.
The inactivation curve for the first four tests
a pronounced tailing effect after 99.99% of the
activated.
is similar with
bacteria had been
The inactivation curve for the fifth test in which the turbidity
level and the ultraviolet absorption were highest is more erratic,
Due to the non-linearity of the inactivation curves, slope functions were
not calculated; however, the inactivation curve for the first four tests
were similar enough to permit the observation that the decreasing rate
of inactivation in each case was similar. This similarity is better
indicated by plotting the survival ratio against the time of exposure,
as in Figure 4. This also demonstrates that a variation in the average
ultraviolet intensity in the range 194-279 uw/cm2 had little effect on
the inactivation of the bacteria.
22
-------
10-'
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Relative U-V Dose x, IOOO in uw/sec/cm2
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FIG. 3
COLIFORM SURVIVAL CURVES
90
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COLIFORM SURVIVAL CURVES
25
-------
B. DYNAMIC TESTS
Based on the static experiments, tests were conducted under actual flow
conditions in the ultraviolet disinfection chamber. From the static
tests it was indicated, except for high initial coliform density and
high turbidity, an exposure period of 120 seconds produced an effluent
with a coliform MPN index below 70/100 ml. To provide a small safety
factor the exposure period was selected at 130 seconds.
Prior to each day's testing, the troughs and ultraviolet chamber were
cleaned and flow conditions re-established a minimum of 15 minutes
before samples were collected for assay. The ultraviolet lamps were
prewarmed for the same minimum period .
The results of the tests from the various days' testing are shown in
Appendix D. The exposure period varied from 128 seconds to 130 seconds.
Turbidity levels in the independent samples of irradiated effluent varied
from 2 to 23 JTU. In Figure 5, the coliform MPN index per 100 ml from
76 independent samples is plotted against the turbidity. From the
plotting, it is indicated that for the given conditions of exposure in
the ultraviolet chamber, a turbidity level above 11 JTU grossly inter-
feres with the ultraviolet inactivation of the bacteria. Of the 76
samples, 53 samples had a turbidity level below 11 JTU, and 23 samples
had a turbidity level above 11 JTU. Of the 53 samples with a turbid-
ity level below 11 JTU, only two samples had a coliform MPN Index
per 100 ml over 70. In the samples with a turbidity level over 11 JTU,
13 of the 23 samples had a coliform MPN Index per 100 over 70.
The results of these tests were also compared in another way. Irradiated
samples, which had a coliform level below 70/100 ml, were classified as
acceptable and unacceptable if the value exceeded 70/100 ml. The results
were then plotted against the individual ultraviolet intensity readings
and the turbidity value of the sample. This plot is shown in Figure 6.
As the residual ultraviolet intensity is reduced and the turbidity value
increases, the number of failures increased.
C. U.V. ABSORPTION
To determine the association between ultraviolet absorption,
turbidity and organic matter in the sewage, a series of observ-
ations were taken. For each observation, the absorption coefficient,
turbidity level and organic level was determined. The measure of
organic material used was determined by the Chemical Oxygen Demand
Test.
The results of the observations are shown in Table 4 and Figure 7.
Comparison of the data was made by a programmed step-wise regression
analysis. The calculated absorption coefficient was the dependent
variable and the COD and turibidity values were the independent
variables. The results of the analysis are shown in Table 5.
26
-------
450
350
§ 300
S.
* 250
E 200
E
IOO
TOC
50
0 I 2345 6 789 10 II 12 13 14 15 16 17 18 19 20 21 22 23
Turbidity J.T.U.
FIG. 5
COLIFORM M.P.N. VS. TURBIDITY FOR
76 DYNAMIC TESTS
27
-------
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20
25
FIG. 6
U-V INTENSITY VS. TURBIDITY
DYNAMIC TESTS
28
-------
TABLE 4
U-V ABSORPTION COEFFICIENT, COD, AND TURBIDITY DATA
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Absorption
Coefficient
k/in.
.722
.204
.052
.204
.718
.569
.604
.722
.718
.356
.551
.580
.651
.594
.270
.612
.558
.708
.558
.377
.533
.380
COD
mg/1
65
15
15
20
61
46
56
55
49
35
31
40
51
50
20
44
48
47
38
23
41
20
Turbidity
JTU
10
3
1.5
6.5
15
5
7
10
15
17
5.5
7
6
6
2.5
5.5
5
7.5
4.5
7
35
2
1. Calculated from I/I = e
-kd
29
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COD mg/l
60
FIG.7
SAMPLE REGRESSION OF
ABSORPTION ON C.O.D.
30
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The summary indicates that most of variance of the dependent
variable is explained by the organic level and addition of turbid-
ity measures contributed little to the regression. The partial
F. test of the null hypothesis B] = 62 = 0, indicates a significant
relation of COD to absorption and the turbidity values contribute
little. The multiple correlation coefficient of absorption versus
COD is .9098 and was only increased to .91 by additon of the
turbidity.
The proportion of the variance of the absorption coefficient that
can be attributed to the linear regression on COD would be 82.77%
and increased .04% with the inclusion of turbidity values in the
regression.
The indication that about 83% of the variance of absorption coeffic-
ient can be attributed to its linear regression on COD does not
exclude a relation between COD and turbidity. A linear regression
analysis between COD and turbidity gave a correlation coefficient
of .529, indicating about 28% of the variance of the COD values can
be attributed to the regression as turbidity.
Turbidity has some effect on the absorption of ultraviolet by sewage,
but the indication is that a measure of the COD of the sewage would
be a better indicator.
Artificially added turbidity would not envelope the bacteria and
therefore would not have as much of an interference effect on U.V.
efficiency (or penetration) as would pinpoint floe.
D. MIXING IN U-V CHAMBER
Comparison of the dynamic test results with the static tests indi-
cated that lower levels of suspended material during the dynamic
tests affected the coliform level in the irradiated effluent. This
would indicate that mixing in the ultraviolet chamber is not as
efficient as in the static test system. The baffles in the ultra-
violet chamber were set so the flow went over all baffles. The
alternative arrangement, without extensive modification of the
chamber, was to set the baffle so the flow went under alternate
weirs.
The baffles were set in the two settings and for each arrangement
a series of independent samples were taken. A sample of the sewage
before irradiation was taken and then four samples taken of the
irradiated effluent. This was repeated twice for each baffle arrange-
ment. The turbidity during the test varied from 12 to 23 JTU.
The flow rate, and thus the exposure, during the test was uniform.
The data is summarized in Table 6.
32
-------
TABLE 6
EFFECT OF FLOW PATTERN BY BAFFLE CHANGES
Over-Under Baffles
Over Baffles
Y
Coliform Coliform
Turbidity MPN Index Geometric Turbidity MRN Index Geometric
JTU Per 100 ml Mean JTU Per 100 ml Mean
Before Exposure
2780x10'
330x10^
9.57x10'
330x10^
790xl03 1.61xl06
After Exposure
17
18
19
17
14
23
14
16
490xlOu
49x10°
310x10°
130x10°
109x10°
330x10°
130x10°
330x10°
14
13
13
17
17
12
15
l,87x!02 13
79xlOu
210x10°
49x10°
221x10°
490x10°
109x10°
79x10°
33x10° 1.12xl02
Non-parametric test of means in unpaired replicates.
E ranks (Ty) = 55.5 E ranks (Tx) = 80.5
2
T is smaller of Tx and Ty. T = Ty =55.5
For nx=ny=8 the critical value of T = 52
CP=.10 Two sided Test)
Ty = 55.5 T.10 = 52. No significant difference between means of two
samples.
33
-------
Samples of the non-irradiated sewage effluent, during the period
the baffles were set in the over-under position, indicate the
geometric mean coliform density was 9.57 x 1(P per 100 ml. After
irradiation, the geometric mean coliform density was 1.87 x 10^
per ml. Turbidity measures on the samples averaged 17 JTU. During
the period the baffles were in the regular position, the geometric
mean coliform density of the non-irradiated sewage was 1.61 x 10^.
After irradiation, the geometric mean coliform density was 1.12 x
10^. Turbidity measures on the samples averaged 14 JTU.
A comparison of the two treatment means indicates there was no
significant (P = .05 two-sided test) difference between the means of
the two samples.
E. pH VALUE OF SEWAGE.
To check if pH variation in sewage would affect inactivation of the
coliform bacteria, a static experiment was conducted. A sample of
tertiary sewage effluent was collected, well mixed and divided into
two aliquots. One aliquot was exposed to ultraviolet irradiation
with samples drawn at time intervals for coliform determination.
The pH of the second aliquot was lowered by adding buffered pH tablets,
The aliquot was then exposed to ultraviolet irradiation under the
same conditions as the first aliquot. The same procedure was carried
out on a second sample of tertiary sewage effluent.
The results of the determinations made on the sewage samples are
shown in Appendix E. In the first sewage sample, the pH was 7.5 and
changed to 6.0 with the buffered pH tablets. pH of the second sewage
sample was 7.39 and 5.95 after addition of the tablets. Calculated
survival ratios of coliform bacteria plotted against the relative
ultraviolet dose are shown in Figure 8.
The inactivation curve for each sample indicated the characteristic
tailing effect. The decreasing rate of decrease between the two
samples was not similar; however, the rate of decrease between the
aliquots of each sample was similar.
Attempts to raise the pH of sewage effluent to about 8.5 with
buffered pH tablets produced a change in the sewage upon addition of
the buffer tablets. A fine precipitate was formed and the sewage
had a distinct opaque cast. Inactivation experiments at higher
pH values were not carried out.
F. BACTERIA DENSITY
To demonstrate the effect of the bacteria density of sewage subjected
to ultraviolet irradiation, under given conditions of exposure, two
similar experiments were conducted.
34
-------
10-'
IO-2
J .o-3
o
o 10-
IO
-6
10
-7
fo=
1 \V^
1 V*V
\\\
V
\
X
V^V
SV*
VY
\ *
\ i
\
\
\
vv
x\
v\
k "u
\ N
\
\\
_\
\
\
\
V
V
^
s
JL
-\—
\
\
V
\
t
k
ys.
\ .
\
\
x
k
\
\
\
_x \
\
X
\
\
I ' "*
5 A- —4
\ ft 6
X
x
x
\
\
\
y
\
\
\\
\
s
V
s
— wj
\
.a—..
PH
7.5
(
•
5.0
>.95
7.39
^
^
— ' "•«
^>^
h^
^^*
" -*«^
"^ ^
ki=
D 10 20 30 40 !
Relative dose uw/sec/cm2
( x 100)
0
FIG.8
SURVIVAL RATIO VARIATION
WITH PH
35
-------
A sample of tertiary sewage effluent was collected, well mixed and
divided into two aliquots. One aliquot was exposed to ultraviolet
irradiation under static conditions. Coliform determinations were
made on the sample before ultraviolet exposure and after 160 seconds
exposure. The bacteria density of the second aliquot was increased
with an inoculum of K-37 E Coli cells and then subjected to similar
static ultraviolet irradiation. The experiment was repeated on a
second sample of tertiary sewage effluent.
The results of the two experiments are summarized in Table 7. In
the first experiment, the geometric mean density of the non-seeded
sample was 4.26 x 105 per 100 ml and 93 per 100 ml after 160 seconds
exposure. The geometric mean coliform density of the seeded aliquot
was 1.01 x 108 per 100 ml and 2.3 x 10^ per 100 ml, after a similar
exposure.
In the second experiment, the geometric mean coliform density of the
non-seeded sample was 9.54 x 105 per TOO ml and 21 per 100 ml after 160
seconds exposure. The geometric mean density of the seeded aliquot be-
fore and after 160 second exposure was 12.4 x 106 and 2.76 x 103 per
100 ml respectively. In each case, the sample with the higher initial
bacteria density had a higher number of surviving bacteria.
G. SHIELDING OF BACTERIA BY SUSPENDED MATTER IN IRRADIATED SEWAGE
EFFLUENT
To determine if an increased level of suspended material in a sewage
sample under given conditions of exposure afforded the bacteria a
significant degree of protection several experiments were conducted.
With the ultraviolet disinfection unit in operation, a series of
independent samples of the irradiated effluent were taken. Coli-
form determinations were made on the samples following standard
procedures. Each sample was shaken the prescribed 25 times before
the proper amount was withdrawn for inooculations into fermentation
tubes. After this procedure was carried out the remainder of the
sample was mixed for one minute in a high speed mixer. After the
machine mixture, proper amounts of the sample were again taken for
coliform determinations.
The above procedure was carried out on a series of irradiated effluent
samples in three independent tests. In each run the turbidity level
of the sewage was different. The results are summarized in Table 8.
In the first series of samples with an average turbidity value of
4 JTU (range 3 to 6 JTU) there was no significant difference between
the two treatment sample means. The two series of samples, with
higher turbidity levels, indicated the means of the sample assayed
with mixing as prescribed by standard procedures was significantly
smaller (significance level of P=0.10).
36
-------
TABLE 7
EFFECT OF BACTERIA DENSITY
Exoosure
Time
Seconds
Nov. 10, 1969
0
0
160
160
Col i form
No Seed
230xl03
790xl03
r\
109x10°
79x10°
MPN
6.M.
4.26xl05
1
9.3x10*
Index
Per 100 ml
Seeded Aliquot 6.M.
790xl05 l.OlxlO8
ISOOxlO5
? 4
230x10^ 2.3x10^
230xl02
AVG. U.V. DOSE = 80 uw/cm'
Nov. 17, 1970
0
0
160
160
1300x10° 9.54x10^
700xl03
21x10° 2-lxlO1
22x10
o
AVG. U.V. DOSE = 94 uw/cm
700x10
2210x10
230x10
230x10
1
1
1.24xlOx
2.76x10^
37
-------
TABLE 8
COLIFORM DETERMINATIONS MADE ON IRRADIATED SEWAGE SAMPLES
AFTER DIFFERENT METHODS OF MIXING
Exposure Time 114 Seconds Exposure Time Seconds Exposure Time Seconds
Coliform MRN Index
per 100 ml
Coliform MPN Index
per 100 ml
Coliform MPN Index
per 100 ml
'urb.
OTU
6
5
5
4
4
4
4
3
3
3
3
3
Reg.
Mixing
8
8
23
11
5
13
22
2
2
8
5
0
Machine
Mix
14 Ca]
8
7
2
11
13
13
5
7
8
7
8
Turb.
OTU
7
7
7
7
7
7
8
7
10
8
8
8
Reg.
Mixinq
8
5
49
5
11
13
13
13
46
13
33
79
Machine
Mix
1Kb)
33
130
23
17
13
33
33
130
33
49
21
Turb.
JTU
21
23
22
23
22
22
22
21
20
20
20
20
Reg.
Mixing
49
33
33
33
79
79
17
23
13
11
13
33
Machine
Mix
49(b)
49
79
79
109
23
49
79
23
23
33
33
4 Avg.
(a) No significant difference between sample means (P=0.10 two sided test)
(b) Means of samples assayed with mixing prescribed by standard procedures
significantly smaller. (P=0.10 two sided test.
38
-------
H. PHOTOREACTIVATION
With the ultraviolet disinfection unit in operation a sample of the
irradiated effluent was collected and replicate coliform determin-
ations made. The sample was divided into two aliquots. One aliquot
was exposed to the visible light and the second was kept in the
dark. After one hour exposure each sample was assayed for coliform.
The results of these tests are summarized in Table 9.
From the results it is indicated that bacterial multiplication in
the aliquot exposed to sunlight immediately after U.V. exposure
continued at an exponential rate, jhe density of bacteria in the
aliquot kept in the dark declines, but then multiplied after ex-
posure to sunlight. A comparison is indicated in Figure 10.
The calculated relative dose of U.V. in the first photoreactivation
experiment was 14,514 uw/sec/cm2 and in the second experiment was
7811 uw/sec/cm2. In each case it was obvious that some of the
bacteria had not received a lethal dose of U.V. and exposure to
visible light favored continued multiplication.
Two experiments were carried out to determine the dose at which sub-
sequent exposure of the sample to visible light would not favor
photoreactivation. These tests were conducted with static exposure
of the sewage. The sample was assayed before exposure to U.V.,
after an exposure of 33,000 uw/sec/cm2, the irradiated sample after
1 hour exposure to visible light. The results are summarized in
Table 10. In test one, no increase in coliform density was indi-
cated in the irradiated sample exposed to visible light. In test
two multiplication of the bacteria is indicated in the irradiated
sample after exposure to visible light. From these test results
it is indicated a dose in excess of 33,000 uw/sec/cm2 would be
necessary to prevent photoreactivation.
I. BACTERIOPHAGE
To check the kinetics of phage inactivation by ultraviolet radia-
tion, several static experiments were conducted. A sample of
tertiary effluent was collected, and innoculated with f2 phage.
The sample was well mixed and exposed to ultraviolet radiation. At
time intervals samples were withdrawn and assayed for phage.
The results of these experiments are shown in Appendix F and
summarized in Table 11. The survival ratio from each experiment
is plotted in Figure 11.
From the semi log plot, within the range of exposure, it is indicated
that first order kinetics apply for f2 exposed to ultraviolet radia-
tion.
39
-------
TABLE 9
EFFECT OF PKOTOREACTIVATION
Collform MPN Index per 100/ml*
Calculated Dose
14,514 uw/sec/cro*
After Exposure
21
After 1 Hr.
light exp.
176
Sample
Kept in Dark
*Geometric mean of 7 replicate determinations.
From these results it is obvious that exposure to visible light after
ultraviolet exposure favors the continued multiplication of the bacteria,
where as a decline in density was noted in the sample kept in the dark.
40
-------
Sewage Flew
Exposed to
visible light
26UIO*x[
315 x IO°x
1161 x IO°X
X 228 X
U.V.
Disinfection
Chamber
| 10 min. Composite Sample
64x10°
O-min
20-min
50-min
8 O-min
Kept in dark
9x 10°
Exposed to
visible light
x!57x 10°
PI x2!2 x 10°
FIG. 9
COLIFORM SURVIVAL IN LIGHT
AND DARK
"p further check on the photoreact i vat ion of ultraviolet irradiated
ac*-eria, a test was co-ducted as indicated ir : iqure 9. Results
of the coliform assay for each sampling point is also indicated.
41
-------
0 13
0
" 12
X
E M
O
0 10
&9
X
5 8
c
c 7
o.
:•
1 5
"5
« 4
3
2
1
/
^
**» -— '
,*-— •
fcr-"
_ i
S
f
—
^
r "**
1
1
/
\
\
/
/
In
ex
lit
-
•a die
pose
Iht
ited
d to
son
visi
rradiated s<
kept in dark f
20 mins. and
exposed to v
light i
iple
trie
impU
or
then
isibl
t
•
0 10 20 30 40 50 60 70 80 90
Time- mins.
FIG. 10
COLIFORM SURVIVAL IN LIGHT
AND DARK
42
-------
TABLE 10
EFFECT OF PHOTOREACTIVATION AT HIGH U.V. EXPOSURES
TEST I
TEST 2
Coliform
MPN Index
per 100 ml
Geometric
Mean
Sanole Before Irradiation
230x10-
230x10-
230x10-
Coliform
MPN Index
per 100 ml
230x10°
330xl03
Sample After U.V. Exposure 33,000 uw/sec/cm
2
2xlOc
2x1 Oc
2xlOl
2xlOc
Geometric
Mean
276x10"
2x1 Oc
Irradiated Sample After One Hour Exposure
2x10"
2xlOc
2x10"
11x10"
8x1 Oc
9x10'
Non-Irradiated SampTeAfter One Hour Exposure
130x10-
230x10'
173x10^
330x10-
221x10-
270x10-
43
-------
TABLE 11
f2 PHAGE INACTIVATION
2 3 4
Date
pH
Temperature
J\mm. Nitro.
Total Iron
Turbidity ^
°c
mg/1
mg/1
TU
Nov. 5, 1969
7.48
18
0
0.31
9
! Nov. 12, 1969 i
; j
i 7.25
" l"~' ' "
17
0
0.36
: 10
Nov. 25, 19
7.19
14
0
0.33
6
69! Dec. 4
1 7.
i
j 9
; o
,' P-
! 3
, 1969
35
31
Absorption
Coefficient
Average absolute
Dose uw/cm2
.92
111
.92
75
.996
108
Exp. Time
Sec.
40
80
120
160
RELATIVE DOSE
4440 j
8880 i
13320
17760
ULTRAVIOLET
3000
6000
9000
12000
p
uw/sec/cm
i 4320
1 8640
1 12960
1 17280
j__3960 ,
' 7920
i 11880
1 15840
.92
99
PLAQUE COUNTS AND SURVIVAL RATIOS
0
40
80
120
160
PFU
IxlO7
2.34xl06
3.20xl05
5.40xl04
1.14xl04
2
3
5
1
N/No
_
.3X10"1
.2xlO"2
.4xlO~3
.IxlO"3
PFU
1.63xl05
8^55xl03
l.OSxlO3
1.05xl02
l.OOxlO1
5.
6.
6.
6.
N/No
_
2xlO"2
3xlO"3
4xlO"4
IxlO"5
PFU
8.9xl04
2.42xl04
2.19xl03
3.35xl02
4X101
N/No
2.7X10"1
_9
2.5x10
3.8xlO"3
4.5xlO"4
PFU
1.44X105
3.45X104
"3
lAiiSxlO0
i^ 3
1.01xlOJ
l.BxlO2
2.
3.
7.
1.
__N/NQ .
4x10" J
8xlO"2
OxlO"3
OxlO~3
44
-------
10-2:
IO-3_
o
X
o
tr
IO-4_
IO-5_
\,
(I) 11-5-69
(2) 11-12-69 © ©
(3) 11-25-69 A A
(4) 12-4-69 a a
\
,\
5000 10,000
Relative U-V dose
15,000 20,000
UW/SEC /CM2
FIG. II
INACTIVATION CURVE FOR F2 PHAGE
45
-------
J. BACTERIQPHAGE PHOTOREACTIVATION
To check on the photoreactivation of f2> several experiments were
conducted on tertiary sewage effluent seeded with fg phage and
exposed to ultraviolet radiation in the disinfection chamber.
The sampling plan is indicated by Figure 12.
The results of these experiments are summarized in Table 12. The
results indicate no change in phage density in the irradiated sample
exposed to visible light or kept in the dark. However, the controls
showed no significant multiplication indicating the lack of a suit-
able host.
Another experiment conducted with K-37 host cells added to the f£
phage seed, and to the irradiated sample. The results of this test
is shown in Table 13.
46
-------
B.U. Sample — Before Ultraviolet Treatment
A.U. Sample-After Ultraviolet Treatment
Effluent
-I U.V. Chamber
A.U. Sample
nn
V. A.U. Sample, kept
in dark
-A.U. Sample, light
exposed
M Phage
Seed
B.U. Sample
B.U. Sample
1-hr, light
exposure
FIG. 12
SAMPLING PLAN FOR PHAGE PHOTOREACTIVATION
TEST
47
-------
TABLE 12
f2 PHAGE PHOTOREACTIVATION
PFU/ml
SAMPLE 1 I 3
Sample before exposure (BU) 15,100 4250 6050
Sample after exposure (AU) 0 12 0
Irradiated sample exposed to
visible light for 1 hr. [AU ) 0 13 0
Irradiated sample exposed to
visible light for 2 hr. (AU ) - - 0
Irradiated sample kept in dark
for one hour 0 15 -
Sample (BU) exposed to visible
light for one hour (control) 13,300 8770 6150
Calculated minimum relative
dose uw/sec/cm2 11,160 11,210 1885
48
-------
TABLE 13
Photoreactivation of fp phage with added K-37 host cells.
PFU/ml
Sample before exposure with f? phage + K-37 r
host cells BU ^ 4.3x10°
Irradiated sample (AU) 1545
Irradiated sample + K-37 cells exposed to
visible light for one hr. 2200
Sample (BU) exposed to visible light for one «
hr. (control) 4.7x10
2
Ultraviolet Dose mw/sec/cm 3480
From this test it is indicated that phage subjected to a sub-lethal dose
of ultraviolet radiation and exposed to visible light in the presence of
a suitable host would continue to multiply.
49
-------
SECTION X
REFERENCES
1. U. S. Public Health Service Publication No. 1500, "National Register
of Shellfish Production Areas".
2. Bradley, E. F., "Advanced Wastewater Control System," Journal. Water
Pollution Control Federation.
3. "Standard Methods for the Examination of Water and Wastewater", 12th
Edition, American Public Health Association, New York, 1965.
4. U. S. Army Chemical Corps, Technical Report BL 28, "Use of Ultra-
violet Radiation in Microbiological Laboratories".
5. Luckiesh, M., and Holladay, L. L., "Disinfecting Water by Means of
Germicidal Lamps", General Electric Review, 47, pp 45-50, 1944.
6. U. S. Public Health Service Publication No. 33, Part I, "National
Shellfish Sanitation Program Manual of Operations - Sanitation of
Shellfish Growing Areas".
7. General Electric Co., Large Lamp Division, "Germicidal Lamps",
Catalog, p 122.
50
-------
SECTION XI
GLOSSARY
Bacten'ophage - Viruses which are parasitic to bacteria.
B.O.D. (Biochemical Oxygen Demand) - Amount of oxygen used
by microorganisms in the stabilization of organic matter at
20° in 5 days.
C.O.D. (Chemical Oxygen Demand) - The measure of the oxygen
demand of sewage in a two hour sulfuric acid-dichromate re-
flexing.
Col i form Organisms - A group of bacteria recognized as in-
dicators of fecal pollution.
Germicidal Ultraviolet Plant - Ultraviolet lamp that has most
of the energy generated at a predominant wavelength of 2537
Angstrom units I
J.T.LI. - A measure of turbidity in Jackson Turbidity Units.
Kl - Absorption Coefficient Per Inch - The fraction of the
remaining ultraviolet intensity absorbed per inch of solution,
described by the equation I=I0e~Kd.
_2_ - Ultraviolet radiation intensity, microwatts per square
centimeter.
_o_ - Initial ultraviolet radiation intensity.
e_ - Base of natural logarithms.
M.P.N. - An estimate of the number of col i form organisms per
100 milliliters of sample based on probability formulas.
51
-------
SECTION XI
APPENDICES
A. Public Health Service Policy Statement on the
Use of the Ultraviolet Process for Disinfection
of Water 53
B. Operating Instructions, Instrument and Safety
Control Relay Box , 56
C. Static (Batch) Test Data - Ultraviolet Irradiation of
Sewage Effluent 59
D. Dynamic (Flow Through) Data - Ultraviolet Irradiation
of Sewage Effluent 70
E. Static Test Data - Ultraviolet Irradiation of Sewage
Effluent at Different pH Values 76
F. Static Test Data - Ultraviolet Irradiation of f2
Phage in Sewage Effluent gg
52
-------
APPENDIX A
April 1, 1966
DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
PUBLIC HEALTH SERVICE
Division of Environmental Engineering and Food Protection
Policy Statement on:
USE OF THE ULTRAVIOLET PROCESS FOR DISINFECTION OF WATER
The use of the ultraviolet process as a means of disinfecting water to
meet the bacteriological requirements of the Public Health Service
Drinking Water Standards is acceptable provided the equipment used
meets the criteria described herein.
In the design of a water treatment system, care must be exercised to
insure that all other requirements of the Drinking Water Standards
relating to Source and Protection, Chemical and Physical Characteristics,
and Radioactivity are met. (In the case of an individual water supply,
the system should meet the criteria contained in the "Manual of Individ-
ual Water Supply Systems", Public Health Service Publication No. 24).
The ultraviolet process for disinfecting water will not change the
chemical and physical characteristics of the water. Additional treat-
ment, if otherwise dictated, will still be required, including possible
need for residual disinfectant in the distribution system.
Color, turbidity and organic impurities interfere with the transmission
of ultraviolet energy and may decrease the disinfection efficiency below
levels required to insure destruction of pathogenic organisms. It may
be necessary to pretreat some supplies to remove excessive turbidity
and color. In general, units of color and turbidity are not adequate
measures of the decrease that may occur in ultraviolet energy transmission.
The organic nature of materials present in waters can give rise to
significant transmission difficulties. As a result, an ultraviolet inten-
sity meter is required to measure the energy levels to which the water is
subjected.
Ultraviolet treatment does not provide residual bactericidal action.
Therefore, the need for periodic flushing and disinfection of the water
distribution system must be recognized. Some supplies may require routine
chemical disinfection, including the maintenance of a residual bactericidal
agent throughout the distribution system.
53
-------
Criteria for the Acceptability of an Ultraviolet
Disinfecting Unit
1. Ultraviolet radiation at a level of 2,537 Angstrom units must be
applied at a minimum dosage of 16,000 microwatt-seconds per square
centimeter at all points throughout the water disinfection chamber.
2. McLximum water depth in the chamber, measured from the tube surface
to the chamber wall, shall not exceed three-inches.
3. The ultraviolet tubes shall be:
a. Jacketed so that a proper operating tube temperature of about
105°F. is maintained, and
b. The jacket shall be of quartz or high silica glass with similar
optical characteristics.
4. A flow or time delay mechanism shall be provided to permit a two
minute tube warm-up period before water flows from the unit.
5. The unit shall be designed to permit frequent mechanical cleaning of
the water contact surface of the jacket without disassembly of the
unit.
6. An automatic flow control valve, accurate within the expected press-
ure range, shall be installed to restrict flow to the maximum design
flow of the treatment unit.
7. An accurately calibrated ultraviolet intensity meter, properly
filtered to restrict its sensititivy to the disinfection spectrum,
shall be installed in the wall of the disinfection chamber at the
point of greatest water depth from the tube or tubes.
8. A flow diversion valve or automatic shuf-off valve shall be installed
which will permit flow into the potable water system only when at
least the minimum ultraviolet dosage is applied. When power is not
being supplied to the unit, the valve should be in a closed (failsafe)
position which prevents the flow of water into the potable water
system.
9. An automatic, audible alarm shall be installed to warn of malfunction
or impending shutdown if considered necessary by the Control or
Regulatory Agency.
10. The materials of construction shall not impart toxic materials into
the water either as a result of the presence of toxic constituents
in materials of construction or as a result of physical or chemical
changes resulting from exposure to ultraviolet energy.
54
-------
11. The unit shall be designed to protect the operator against elec-
trical shock or excessive radiation.
As with any potable water treatment process, due consideration must be
given to the reliability, economics and competent operation of the dis-
infection process and related equipment, including:
1. Installation of the unit in a protected enclosure not subject
to extremes of temperature which could cause malfunction.
2. Provision of a spare UV tube and other necessary equipment to
effect prompt repair by qualified personnel properly instructed
in the operation and maintenance of the equipment.
3. Frequent inspection of the unit and keeping a record of all
operations, including maintenance problems.
55
-------
APPENDIX B
OPERATING INSTRUCTIONS
INSTRUMENT AND SAFETY CONTROL RELAY BOX
GENERAL
The relay control box is designed to provide the necessary safeguards
to prevent discharge of improperly treated waste into the bay. The
switches and relays are arranged so that the diversion gate will be
dropped in any of several eventualities: power failure, excess
turbidity, low ultraviolet light intensity, failure of one of the
sixteen ultra-violet lamps, or high water in the sterilization chamber.
If one or more of these things occur, the solenoid holding the div-
ersion gate will be de-energized permitting the gate to drop, diverting
the flow to the holding lagoon. Except in the case of power failure,
when the gate has dropped, the solenoid again will be energized to
lock the gate down until the trouble has been corrected. In all cases,
the battery operated alarm will be sounded and will continue to sound
until the silencing switch is operated, or until the battery fails.
There are five pilot lights designed to alert the operator as to the
type of trouble encountered. These lights cannot be turned off, nor
the gate locked up, until the trouble has been corrected. The oper-
ation of each circuit will be detailed below.
In addition, the relay box contains the timer to control the operation
of the two samplers and the chemical feed pump, in accordance with the
flow, as indicated by the flowmeter. The timer is field adjustable so
that the desired percentage of sampler or pump on time can be set as
experience dictates.
SAMPLERS AND CHEMICAL FEED PUMP
The two samplers and one chemical feed pump are controlled by the flow
meter and a relay and timer in the relay box. There is also a disconnect
switch in the box with which to turn the pumps on or off. The timer
consists of two plug-in time delay relays, each with double pole, double
throw contacts. When the flowmeter indicates approximately 400 gallons
have passed the measuring point, it closes a contact for 25 mini-seconds,
This in turn energizes a relay in the relay box through a normally closed
contact on the timer. When the time delay relays are energized, depend-
ing on the time setting, the sampler and chemical feed pump can be
operated for a period up to about sixty seconds. Either the samplers or
the chemical feed pump can be shut off first. The time delay relay with
the longest time setting will reset the timers ready for the next pulse
from the flowmeter.
56
-------
TURBIDITY METER
The turbidity meter measures the turbidity of the liquid and if the
turbidity exceeds the set point closes a contact to operate the
turbidity relay in the relay box. This relay seals itself in, so
that a subsequent decrease in turbidity has no effect until the
manual reset button is pressed. At the same time the turbidity
relay operates, it de-energizes the gate solenoid permitting the
gate to drop, diverting the flow to the lagoon. At this time, the
excess turbidity pilot light will turn on and after the gate has
dropped, the gate down pilot light will turn on and the alarm bell
will ring. If in fact the turbidity has returned to normal, push-
ing the reset button, this will permit the gate to be raised and
locked up. This will also de-energize the relay and turn off the
excess turbidity light. However, if the turbidity is still high,
pushing the reset button will have no effect.
LOW ULTRA-VIOLET INTENSITY
There are four photo-cells which sense the intensity of the ultra-
violet light penetrating the liquid. Through a switch located outside
the relay box and by closing the instrument panel, any one of these
sensors can be connected to the UV analyser in the instrument panel.
Whenever the intensity sensed falls below the set point, as determined
by the analyser, a contact in the analyser will open, de-energizing
the intensity relay in the relay box. This will, in turn, light the
low intensity pilot light, and de-energize the gate solenoid. However,
to prevent false indications caused by solids flowing over the photo-
cell, the relay box contains a time delay relay, which prevents oper-
ation of the intensity relay for a period of ten seconds. Thus, a
momentary loss of intensity will not cause diversion with the sub-
sequent alarm conditions, but a loss exceeding ten seconds, as set
on the pneumatic time delay relay, will cause diversion.
ULTRA-VIOLET LAMP FAILURE
There are sixteen ultra-violet lamps under four hoods to provide steril-
ization of the effluent. These lamps, with ballasts draw approximately
nine amperes. If one lamp fails, the current will be reduced approx-
imately 0.5 amperes. The current meter - which in fact is a volt meter
operating in conjunction with the transformer in the relay box - will
sense this drop in current and cause the qate to drop. The meter is
adjustable so that if at some future date it is found that less than
sixteen lamps are needed, the lamp failure protection can still be
obtained. Operation of the reset button will not have any effect un-
less the faulty lamp has been replaced. The reset button must be
operated to re-energize the lamp relay and permit the gate to be
raised. All the time the UV Lamps are on, an orange pilot light on
the relay box will be lit, and will go out in the event of failure of
the lamp circuit. This lamp is also used as a "power on, conditions
normal" indicator.
57
-------
Inside the relay box there are two "defeat" switches; one for the in-
tensity and one for lamp current. Since the UV Lamps take time to
warm up and reach final operating current, it is desirable to prevent
false indications of lamp failure during this warm-up period. This
can be accomplished by placing the current defeat switch in the
"defeat" position, returning it to normal after the lamps have been on
for approximately fifteen minutes. The intensity defeat switch can be
used to maintain operation normally in the event of trouble with the
analyser. Unless these switches are in the "defeat" position, diver-
sion by either low intensity or lamp failure must be corrected before
the relays can be reset and the diversion gate locked up.
Each ultra-violet lamp hood, containing four lamps, is equipped with
a Microswitch, arranged so that if any hood is lifted, all sixteen
lamps will go off. This is to protect the operator from exposure to
the extremely intense ultra-violet light. Operation of the hoods will,
of course, cause diversion of the flow, unless the operator is author-
ized to place the defeat switches in the "defeat" position when raising
the hoods for normal maintenance.
HIGH WATER ALARM
Since the mixture of water and electricity is dangerous, two probes
are provided to sense the rise of water level in the ultra-violet
chamber. These probes operate on 12 volts AC and draw a total of
two milliamperes current, which makes them intrinsically safe. When
water bridges between the probes, it completes a circuit between the
highwater alarm transformer and the rectifier. This energizes the
rectifier which is connected to the high water sensing relay. This
is a sensitive relay, operating on 2 milliamperes and 12 volts DC.
This relay, in turn, operates the high water alarm relay. The high
water alarm relay, when energized, turns off the UV lamps and turns
on the high water alarm pilot light. The loss of UV, in turn, oper-
ates the intensity relay to cause diversion of the flow to the lagoon.
DIVERSION GATE
Whereas the diversion gate, obviously, is not in the relay box, it's
operation is controlled by the seventh relay in the box and will be
discussed here. The gate relay is normally energized through the
contacts on the turbidity, intensity and lamp current relays. If
any of them is operated, the circuit to the gate relay is opened,
de-energizing the relay. The gate locking solenoid is energized when
the gate relay is energized under normal conditions. Thus, when
the gate relay is de-energized, the gate solenoid is also de-energized,
permitting the gate to drop. When the gate does in fact drop, a Micro-
switch senses the gate in the down position and through a normally
closed contact on the gate relay again energizes the gate solenoid
to lock the gate in the down position. Located conveniently to the
gate is a push button with one normally closed and one normally open
contact. All current to the gate solenoid goes through this push
button, using the normally closed contacts.
58
-------
Thus, when the conditions are returned to normal, it is necessary to
push this button to unlock the gate so that it can be raised. At the
same time, the normally open contacts close, re-energizing the gate
relay to re-energize the gate solenoid after the gate has been raised,
and the push button released. If conditions are not normal, and all
affected circuits return to normal by means of the reset buttons, the
gate solenoid will not be energized after the gate has been raised, and
the gate will immediately drop again.
Whenever the gate relay is de-energized, the alarm will ring. However,
the gate down lamp will not light unless the gate has in fact dropped
and been locked. Thus, if at any time the alarm is ringing, and the
gate down light is not lit, it can be assumed the gate has, for some
reason, failed to drop completely and it will be necessary to examine
the gate first to remove any obstruction so that flow will be diverted
while cause for diversion is being corrected. On the cover of the
relay box is an alarm silencing switch to turn off the alarm and pre-
serve the battery.
59
-------
APPENDIX C
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
June 9, 1969
Turbidity JTU
pH o
Temperature C
16
7.51
23
Ammonia Nitrogen mg/1 12.5
Total Iron mg/1 0.13
BOD,- mg/1 63
Calculated average intensity in
Trough 2.
lave = I 0 - e"kd)
kd
lave =5.38 (1 - .044)
3.1
lave = 1.66
Ultraviolet Intensity
Measured with
Probe 1 C.F. - 122
Trough 1 I na 4.7
Trough 1 1° ua .21
Trough 2 I, ua .24
Depth inches 2.81
Average absolute dose
lave x C.F.
1.66 x 122
203 uw/cm
Absorption Coefficient
*-M - V'o
e"kd = .21/4.7
k = 1.I/inch
Calculated relative dose for
exposure period.
203 uw/cm2 x 40 sec = 8120 uw/sec/cm2
x 80 " =16240
x!20 " =24360
x!60 " =32480
Calculated I in Trough 2 where
exposure was made
Io = I./e
-kd
IQ = .24/.0446
I0 = 5.38
60
-------
APPENDIX C
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
Date: June 9, 1969
#
60901A
B
C
60902A
B
C
60903A
B
C
60904A
B
C
60905A
B
C
Exposure
Time Sec.
0
0
0
40
40
40
80
80
80
120
120
120
160
160
160
Coll form Index
MPN/100 ml.
790 x lo14
790 x 10^
790 x 10^
16090 x 101
5420 x 101
16090 x 101
1720 x 10°
1720 x 10°
2300 x 10°
49 x 10°
130 x 10°
94 x 10°
49 x 10°
79 x 10°
33 x 10°
Geometric
Mean of Survival Ratio
MPN Index N/No
7.9 x 106
1.12 x 105 1.4 x 10"2
1.90 x 103 2.4 x 16~4
8.4 x ID1 1.1 x 10~5
5.0 x 101 6.3 x 10"6
61
-------
APPENDIX C
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
Date: June 17, 1969
Turbidity JTU
r>H
0
10
7.23
Temperature UC 23
Ammonia Nitrogen mg/1 0
Total Iron mg/1 0.21
BOD5 mg/1 21
Ultraviolet Intensity
Measured With
Probe 1 C.F. = 12.2
Trough II ua = 4.4
Trough 1 1° ua - .18
Trough 21, ua = .22
Depth inches =2.81
Calculated average intensity in
Trough 2
lave = I Q - e"kd)
kd
lave =5.38 (1 - .0409)
3.2
lave = 1.61 mg
Average absolute dose
lave x C.F.
1.61 x 122 ?
196 uw/cm
Absorption coefficient
e "kd=
= 1. Winch
Calculated I in Trough 2
where exposure was made
Calculated relative dose for
exposure period
196 uw/cm2 x 40 sec = 7840 uW/sec/cm2
x 80 " =15630
x!20 " =23520
x!60 " =31360
lo - Ve
-kd
IQ = .22/.0409
IQ - 5.33
62
-------
APPENDIX C
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
Date: June 17, 1969
#
61701A
B
C
D
E
60702A
B
C
D
E
61703A
B
C
D
E
61704A
B
C
D
E
61705A
B
C
D
E
Exposure
Time Sec.
0
0
0
0
0
40
40
40
•40
40
80
80
80
80
80
120
120
120
120
120
160
160
160
160
160
Col i form Index
MPN/100 ml.
1410 x 103
<
1090 x 10,
700 x 10,
1700 x 10,
250 x 10
278 x lo}
330 x 10}
221 x 10:
490 x 10:
330 x 101
221 x 10°
130 x 10°
172 x 10°
109 x 10°
49 x 10°
7 x 10°
5 x 10°
11 x 10°
14 x 10°
13 x 10°
0
2 x 10°
5 x 10°
2 x 10°
5 x 10°
Geometric
Mean of Survival Ratio
MPN Index N/No
CJ
7.16 x 10°
3.19 x 103 4.4 x 10"3
1.21 x 102 1.7 x 10"4
pr
9 x 10° 1.3 x 10"5
/-
3 x 10° 4.2 x 10"D
63
-------
APPENDLX C
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
June 23, 1969
Turbidity JTU 7
PH 7.25
Temperature C 24
Ammonia Nitrogen mg/1 1.3
Total Iron mg/1 0.22
BOD5 mg/1 8
Calculated average intensity
in Trough 2
lave = IQ 0 - e-kd)
kd
Ultraviolet Intensity
Measured With
Probe 1 C.F. 122
Trough 1 I ua = 4.3
Trough 1 1° ua = 0.24
Trough 2 Ir ua = 0.38
Depth inches = 2.81
Absorption Coefficient
-kd T ..
fe = V'o
-kd
e = 0.24/4.3
k = 1.0/inch
Calculated I in Trough 2
where exposure was made
T/ -kd
I0 - I/e
IQ = 0.38/.0558
I = 6.81 ua
lave =6.81 (1 - .0558)
2.8
lave = 2,29 ua
Average absolute dose
lav x C. F.
2.29 x 122
279 uw/cm2
Calculated relative dose for
exposure period.
2
279 uw/cm x 40 sec. = 11160 uw/sec/cm
x 80 " = 22320
x!20 " = 33480
x!60 " = 44640
64
-------
APPENDIX C
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
Date: June 23, 1969
#
62301A
B
C
D
E
62302A
B
C
D
E
62303A
B
C
D
E
62304A
B
C
D
E
62305A
B
C
D
E
Exposure
Time Sec.
0
0
0
0
0
40
40
40
40
40
80
80
80
80
80
120
120
120
120
120
160
160
160
160
160
Geometric
Coliform Index Mean of Survival Ratio
MPN/100 ml. MPN Index N/No
1300 x 10?
330 x 10, K
790 x 10, 7.27 x 10b
1300 x 10~
460 x 10
1300 x 10}
172 x 10: , ,
460 x lOJ 6.13 x 10J 8.4 x W~*
490 x 10:
1720 x 101
22 x 10°
79 x 10° , ,
70 x 10° 49 x 101 6.7 x 10
49 x 10°
49 x 10°
8 x 10°
6 x 10° n ,.
5 x 10° 6 x 10° 8.3 x 10"D
13 x 10°
2 x 10°
5 x 10°
9 x 10° 6 x 10° 8.3 x 10"6
5 x 10°
5 x 10°
65
-------
APPENDIX C
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
June 30, 1969
Turbidity JTU 24
pH 7.15
Temperatuve C 26
Ammonia Nitrogen mg/1 1.3
Total Iron mg/1 0.2
BODr mg/1 22
Calculated average intensity
in Trough 2.
lave = I Q -
"kd
)
kd
lave =5.44 (1 - .0349)
3.3
Calculated I in Trough 2
where exposure was made.
I0 = I/e
-kd
IQ = .19/.0349
IQ = 5.44
lave =1.59 ua
Ultraviolet Intensity
Measured With
Probe 1 C.F. 122
Trough II ua = 4.3
Trough 1 1° ua = .15
Trough 2 I; ua = .19
Depth Inches = 2.81
Average absolute dose
lave x C.F.
1.59 x 122
194 uw/cm2
Absorption Coefficient
0-kd T/T
e = I/IQ
e"kd = 0.15/^.3
k = 1.17/inch
Calculated relative dose for
exposure period
2
194 uw/'cm
x 40 sec. = 7760
x 80 " =15520
x!20 " =23280
x!60 " =31040
66
-------
APPENDIX C
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
Date: June 30, 1969
#
63001A
B
C
D
E
63002A
B
C
D
E
63003A
B
C
D
E
63004A
B
C
D
E
63005A
B
C
D
E
Exposure
Time Sec.
0
0
0
0
0
40
40
40
40
40
80
80
80
80
80
120
120
120
120
120
160
160
160
160
160
Col i form Index
MPN/100 ml.
1720 x 103
1720 x 10,
790 x 10,
J
490 x 10,
490 x 10J
170 x lo}
330 x 10}
80 x 10}
230 x 10J
490 x 101
33 x 10°
33 x 10°
49 x 10°
120 x 10°
79 x 10°
8 x 10°
5 x 10°
7 x 10°
49 x 10°
23 x 10°
2 x 10°
17 x 10°
5 x 10°
5 x 10°
13 x 10°
Geometric
Mean of Survival Ratio
Col i form Index N/No
p-
8.91 x 105
2.19 x 103 2.5 x 10"3
5.5 x 101 6.2 x 10"5
1.3 x 101 1.5 x 10"5
6.0 x 10° 6.7 x 10"6
67
-------
APPENDIX C
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
Date: July 7, 1969
Turbidity JTU 29
pH 7.2
Temperature C 26
Ammonia Nitrogen mg/1 4.3
Total Iron mg/1 0.24
BOD. mg/1 36
Calculated average intensity in
Trough 2.
lave = I 0 - e"kd)
U — - —" -
kd
lave =4.81 Q - .027)
3.6
Calculated I in Trough 2
where exposure was made
- e
-kd
IQ = 0.13/.027
IQ = 4.81 ua
lave =1.3
ua
Ultraviolet intensity
measured with
Probe 1 C.F. = 122
Trough 1 I ua = 3.7
Trough 1 1° ua= o.l
Trough 2 I: ua = .13
Depth inches =2.81
Average absolute dose
lave x C.F.
1.3 x 122
159 uw/cm2
Absorption Coefficient
e"kd = 0.10/3.7
k = 1.28/inch
Calculated relative dose for
exposure period.
O
159 uw/cm x 40 sec. = 6360 uw/sec/cm2
x 80
x!20
x!60
=12720
=19030
=25440
68
-------
APPENDIX C
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
Date:
#
70701A
B
C
D
E
70702A
B
C
D
E
70703A
B
C
D
E
70704A
B
C
D
E
70705A
B
C
D
E
Exposure
Time Sec.
0
0
0
0
0
40
40
40
40
40
80
80
80
80
80
120
120
120
120
120
160
160
160
160
160
Coli form Index,
MPN/100 ml.
790 x 10^
790 x 10^
1720 x 10^
940 x 10^
2210 x 10J
172 x 102
J
278 x 10,
/
490 x 10,
1300 x 10,
278 x 10^
490 x 10°
230 x 10°
490 x 10°
460 x 10°
490 x 10°
278 x 10°
490 x 10°
172 x 10°
130 x 10°
41 x 10°
230 x 10°
130 x 10°
79 x 10°
94 x 10°
109 x 10°
Geometric
Mean of Survival Ratio
Coli form Index N/No
/»
1.17 x 10°
4f\
_ J
o.oo x iu 3.3 x 10
4.16 x 102 3.5 x 10"4
1.66 x 102 1.4 x 10"4
1.19 x 102 1.0 x 10"4
69
-------
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-------
APPENDIX E
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
AT DIFFERENT pH VALUES
March 16, 1970
Turbidity JTU
PH o
Temperature C
Ammonia Nitrogen
mg/1
Total Iron mg/1
BODC
II 12.
8 8
7.5 6.0
11 11.5
5.6 5.3
.52 .52
9
Calculated average intensity
in Trough 2.
lav = 10 - e"kd)
0
lav = .47 (1 - .1702)
1.75
lav = .223
Ultraviolet Intensity
measured with
Probe 4 C.F.
Trough I I
= 147
= .47
= .08
Trough 1 I ua
Trough 2 if ua = .08
Depth - inches =2.81
Average absolute dose
lav x C.F.
.223 x 147 y
33 uw/cm
Absorption Coefficient
e"kd = .08/. 47
k = .62/ inch
Calculated relative dose for
exposure period.
2
33 uw/cm x 50 sec. = 1650 uw/sec/cm
xlOO " = 3300
x!50 " = 4950
Calculated I in Trough 2 where
exposure was made
'o =
-kd
I = .08/.1702
I0 = .47
76
-------
APPENDIX E
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
AT DIFFERENT pH VALUES
March 16, 1970
EXPOSURE
# TIME SEC.
COLIFORM MPN
INDEX PER 100 ml.
GEOMETRIC MEAN SURVTVAL RATIO
OF COLIFORM INDEX N/No
1 pH 7.50
0
0
50
50
100
100
150
150
2 pH 6.0 Aliquot
0
0
50
50
100
100
150
150
17
10
33
79
.2
.9
49
33
33
11
of above
10
4
10
4
46
17
.9
.9
.9
.9
13
23
x
x
X
X
X
X
X
X
„
10,
10
10,
10
10°
10°
10°
10°
sample.
x
x
x
x
x
x
x
x
103
10,
10*
107
10}
j^
l°n
10°
51
13.7
4
2
x
x
X
X
10
10
10
10
pH lowered with
27.97
7.31
7.3
1.7
X
X
X
X
10
10
10
10
3
«J
buffer
3
i
l
1
2
7
3
.68 x
.83 x
.92 x
1U
w
1U
tablets.
2
2
6
.61 x
.61 x
.08 x
_
10"^
o
Kf3
ID'4
77
-------
APPENDIX E
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
AT DIFFERENT pH VALUES
March 16, 1970
#3 #4
Turbidity JTU
pH o
Temperature C
Ammonia Nitrogen
mg/1
Total Iron mg/1
BODr
7
5.95
9.5
7
7.39
9.5
14.3 14.3
0.60 0.55
12
Calculated average intensity
in Trough 2.
lav = I (1 - e "kd)
kd
lav = .49 Q - .1522)
1.88
lav = .221 ua
Ultraviolet Intensity
measured with
Probe 4 C.F. = 147
Trough I I
Trough 1 I"
Trough 2 I:
Depth inches
ua = .46
ua = .07
ua = .075
= 2.81
Average absolute dose
lav x C.F.
.221 x 147
32
Absorption Coefficient
-kd T/T
e = I/I
e ~kd = .07/.46
= -67/inch
Calculated relative dose for
exposure period.
2
32 uw/cm x 50 sec = 1600 uw/sec/cm
xlOO " = 3200
x!50 " = 4600
Calculated I in Trough 2
where exposure was made
I0 = I/e
-kd
I0 = .075/.1522
I = .49 ua
78
-------
APPENDIX E
STATIC TEST - ULTRAVIOLET IRRADIATION OF SEWAGE EFFLUENT
AT DIFFREENT pH VALUES
March 16, 1970
EXPOSURE COLIFORM MPN GEOMETRIC MEAN SURVIVAL RATIO
# TIME SEC. INDEX PER 100 ml. OF COLIFORM INDEX N/No
3 pH 5.95 Aliquot of sample. pH lowered with buffer tablet
0 17.2 x loj 11.66 x 104
o 7.9 x 10: , ,
50 7.9 x 10, 8.62 x 10^ 7.39 x 1Q~*
50 9.4 x 1(T _ c
100 17 x 10° 11 x 10° 9.44 x 10"°
100 7 x 10° ,
150 5 x 10° 7 x 10° 6.01 x 10"5
150 11x10°
4 ph 7.39
0 13 x 104 13.54 x 104
0 14.1 x I0j , o
50 4.9 x 10, 2.89 x 10^ 2.13 x 10"°
50 1.7 x 10^ n r
100 8 x 10° 9 x 10° 6.65 x 10"D
100 11 x 10° r
150 11 x 10° 7 x 10° 5.17 x 10"°
150 5 x 10
79
-------
APPENDIX F
ULTRAVIOLET IRRADIATION OF F9 PHAGE IN SEWAGE
UNDER STATIC CONDITIONS
November 5, 1969
Turbidity JTU 9
PH 7.48
Temperature C 18
Ammonia Nitrogen tng/1 0
Total Iron mg/1 0.31
Calculated average Intensity
in Trough 2
lav = I.
-kd
IQ = .15/.0709
IQ = 0.12 ua
lav = 2.12 (1 - .0709)
2.6
lav = .76
ua
Ultraviolet Intensity
measured with
Probe 4 C.F. = 147
Trough 1 I ua =1.27
Trough 1 ij ua = .09
Trough 2 l\ ua = .15
Depth Inches = 2.81
Average absolute dose
lav x C.F.
.76 x 147 ?
111 uw/cnT
Absorption Coefficient
-kd _..
e = I/IQ
e ~kd= .09/1.27
k = .92/inch
Calculated I in Trough 2 where
exposure was made
Calculated relative dose for
exposure period
111 uw/cm
x 40 sec = 4440
x 80 " = 8880
x!20 " =13320
x!60 " =17760
80
-------
APPENDIX F
ULTRAVIOLET IRRADIATION OF F9 PHAGE IN SEWAGE
UNDER STATIC CONDITIONS
November 12, 1969
Turbidity JTU 10
PH 7.25
Temperature C 17
Ammonia Nitrogen mg/1 0
Total Iron mg/1 0.36
Calculated average intensity
in Trough 2.
lav = I Q - e"kd)
0 kd
lav =1.43 (1 - .07)
2.6
Ultraviolet intensity
measured with
Probe 4
Trough 1
C.F. =
I ua =
Trough 1 1 ua =
Trough 2 I: ua =
Depth Inches =
147
1.0
.07
.10
2.81
lav = .511 ua
Average absolute dose
lav x C.F.
.511 x 1472
75 uw/cm
Absorption Coefficient
e -". Vlo
e ~kd = .07/1.0
k = .92/inch
Calculated relative dose for
exposure period
75 uw/cm x 40 sec. = 3000 uw/sec/cm 2
x 80 " = 6000
x!20 " = 9000
x!60 " =12000
Calculated I in Trough 2 where
exposure was made
T _ T /„ -kd
IQ = .10/.07
IQ = 1.43 ua
81
-------
APPENDIX F
ULTRAVIOLET IRRADIATION OF F? PHASE IN SEWAGE
UNDER STATIC CONDITIONS
November 25, 1969
Turbidity JTU 6
PH 7.19
Temperature C 14
Ammonia Nitrogen rng/l 0
Total Iron mg/1 0.33
Calculated average intensity
in Trough 2.
lav = I (1 - e "kd)
0
lav =2.19 Q - .0593)
2.8
Ultraviolet Intensity
measured with
Probe 4 C.F =147
Trough 1 I ua = 1.35
Trough 1 1° ua = .08
Trough 2 I: ua = .13
Depth Inches = 2.81
lav = .736
ua
Average absolute dose
lav x C.F.
.736 x 147 ?
108 uw/cm
Absorption Coefficient
-kcL
-V(\
e = .08/1.35
k = .996/inch
Calculated relative dose for
exposure period.
108 uw/cm
x 40 sec.
x 80 "
x!20 "
x!60 "
= 4320 uw/sec/cm2
= 8640
=12960
=17280
Calculated I in Trough 2 where
exposure was made
T _ T /„ -kd
IQ = .13/.0593
IQ = 2.19 ua
82
-------
APPENDIX F
ULTRAVIOLET IRRADIATION OF Fo PHAGE IN SEWAGE
UNDER STATIC CONDITIONS
December 4, 1969
Turbidity JTU 3
pH 7.35
Temperature C 9
Ammonia Nitrogen mg/1 0
Total Iron mg/1 0.31
Calculated average intensity in
Trough 2.
lav = If! - e
lav = 1.89 (1 - .0739)
2.6
lav = .673 ua
Ultraviolet Intensity
Measured With
Probe 4 C.F.
Trough 1 I
Trough 1
Trough 2 ua
Depth Inches
ua
1° ua
147
1.15
.085
.14
2.81
Average absolute dose
lav x C.F.
.673 x 147 7
99 uw/cm
Absorption Coefficient
-kd
e = .085/1.15
k = .92/inch
Calculated relative dose for
exposure period
99 uVcm2 x 40 sec. = 3960 uw/sec/cm2
x 80 " = 7920
x!20 " =11880
x!60 " =15840
Calculated I in Trough 2 where
exposure was made
T _ T /. -kd
IQ = .14/.0739
IQ = 1.89 ua
83
-------
EXPOSURE TIME
SECONDS
APPENDIX F
PLAQUE COUNTS FOR STATIC PHAGE TESTS
P.F.U.
SURVIVAL RATIO
N/No
1.
2.
3.
4.
November 5, 1969
0
40
80
120
160
November 12, 1969
0
40
80
120
160
November 25, 1969
0
40
80
120
160
December 4, 1969
0
40
80
120
160
2.
3.
5.
1.
1.
8.
1.
1.
1.
8.
2.
2.
3.
1.
3.
5.
1.
1.
1
34
20
40
14
63
55
03
05
00
90
42
19
35
4
44
45
45
01
50
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
1°6
105
10$
joj
103
J. \J o
1°2
1°1
101
104
10-
10,
10?
101
105
10!
102
10
2.
3.
5.
1.
5.
6.
6.
6.
2.
2.
3.
4.
2.
3.
7.
1.
3
2
4
1
2
3
4
1
7
5
8
5
4
8
0
0
X
X
X
X
«.
X
X
X
X
..
X
X
X
X
_
X
X
X
X
-I
101
10 ;
lO"13
10~o
10IJ
10 I
10~D
io~i
in"?
10~j,
10"4
i
10-1
l°-3
10 {
10'J
84
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 REPORT NO.
EPA-600/2-75-060
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
ULTRAVIOLET DISINFECTION OF ACTIVATED SLUDGE
EFFLUENT DISCHARGING TO SHELLFISH WATERS
5. REPORT DATE
December 1975 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
J. A. Roeber and F. M. Hoot
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Town of St. Michaels, Maryland
St. Michaels, Maryland 21663
Through subcontract with
Clow Corporation, Florence, Kentucky
10. PROGRAM ELEMENT NO.
1BC611
41042
11. CONTRACT/GRANT NO.
WPRD 139-01-68
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final, 1968-1972
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A tertiary treatment plant and an ultraviolet disinfection chamber were installed
following an activated sludge plant at the municipal sewage treatment plant in
St. Michaels, Maryland. The multiple-tube fermentation technique was used to
determine the total coliform MPN Index after varying exposures to ultraviolet
radiation. Batch tests were sampled at various intervals under constant radiation
and flow-through tests were sampled before and after undergoing radiation. The
standard to be met was an MPN of not more than 70 per 100 ml. In flow-through tests
this was usually achieved with a flow not in excess of 40,000 gallons per day, with
a turbidity of less than 11 JTU, using sixteen germicidal 36 watt ultraviolet lamps,
an energy application of .035 KWH/1000 gallons. The absorption of ultraviolet radi-
ation, as measured by the absorption coefficient, was much more dependent on COD
than on turbidity, indicating the appearance of the effluent is not the best
criterion for estimating the rate of U.V. treatment unit. Both Coliforms and
Bacteriophage multiplied when exposed to visible light after ultraviolet radiation
treatment. Coliform inactivation followed first order kinetics until 99.99%
inactivation occurred; followed by a tailing-off curve. Bacteriophage followed
first order kinetics up to the maximum available ultraviolet rate.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Activated Sludge Process
Disinfection
*Ultraviolet radiation
Coliform bacteria
Chemical removal (sewage treatment)
Shellfish
Turbidity
Static tests
St. Michaels (Maryland)
Package plant
Most probable number
Continuous flow
Photoreactivation
13B
13. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
93
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
85
: 1975 — 657-695/5345 Region 5-1
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