OXYGEN TRANSFER EFFICIENCY SURVEYS AT THE
SOUTH SHORE WASTEWATER TREATMENT PLANT
1985 - 1987
by
Read Warriner
Milwaukee Metropolitan Sewerage District
Milwaukee, Wisconsin 53204
Cooperative Agreement No. CR812167
Project Officer
Richard C. Brenner
Water and Hazardous Waste Treatment Research Division
Risk Reduction Engineering Laboratory
Cincinnati, Ohio 45268
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
Development of the information in this report has been funded in part by
the U.S. Environmental Protection Agency under Cooperative Agreement No.
CR812167 by the American Society of Civil Engineers. The report has been
subjected to Agency peer and administrative review and approved for
publication as an EPA document. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
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FOREWORD
Today's rapidly developing and changing technologies and industrial
products and practices frequently carry with them the increased generation of
materials that, if improperly dealt with, can threaten both public health and
the environment. The U.S. Environmental Protection Agency (EPA) is charged by
Congress with protecting the Nation's land, air, and water resources. Under a
mandate of national environmental laws, the Agency strives to t
formulate and implement actions leading to a compatible balance between human
activities and the ability of natural systems to support and nurture life.
These laws direct EPA to perform research to define our environmental
problems, measure the impacts, and search for solutions.
The Risk Reduction Engineering Laboratory is responsible for planning,
implementing, and managing research, development, and demonstration programs
to provide an authoritative, defensible engineering basis in support of the
policies, programs, and regulations of EPA with respect to drinking water,
wastewater, pesticides, toxic substances, solid and hazardous wastes, and
Superfund-related activities. This publication is one of the products of that
research and provides a vital communication link between the researcher and
the user community.
As part of these activities, an EPA cooperative agreement was awarded to
the American Society of Civil Engineers (ASCE) in 1985 to evaluate the
existing data base on fine pore diffused aeration systems in both clean and
process waters, conduct field studies at a number of municipal wastewater
treatment facilities employing fine pore aeration, and prepare a'comprehensive
design manual on the subject. This manual, entitled "Design Manual - Fine
Pore Aeration Systems," was completed in September 1989 and is available
through EPA's Center for Environmental Research Information, Cincinnati, Ohio
45268 (EPA Report No. EPA/625-1-89/023). The field studies, carried out as
contracts under the ASCE cooperative agreement, were designed to produce
reliable information on the performance and operational requirements of fine
pore devices under process conditions. These studies resulted in 16 separate
contractor reports and provided critical input to the design manual. This
report summarizes the results of one of the 16 field studies.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
m
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PREFACE
In 1985, the U.S. Environmental Protection Agency funded Cooperative
Research Agreement CR812167 with the American Society of Civil Engineers to
evaluate the existing data base on fine pore diffused aeration systems in both
clean and process waters, conduct field studies at a number of municipal
wastewater treatment facilities employing fine pore diffused aeration, and
prepare a comprehensive design manual on the subject. This manual, entitled
"Design Manual - Fine Pore Aeration Systems," was published in September 1989
(EPA Report No. EPA/725/1-89/023) and is available from the EPA Center for
Environmental Research Information, Cincinnati, OH 45268.
As part of this project, contracts were awarded under the cooperative
research agreement to conduct 16 field studies to provide technical input to
the Design Manual. Each of these field studies resulted in a contractor
report. In addition to quality assurance/quality control (QA/QC) data that
may be included in these reports, comprehensive QA/QC information is contained
in the Design Manual. A listing of these reports is presented below. All of
the reports are available from the National Technical Information Service,
5285 Port Royal Road, Springfield, VA 22161 (Telephone: 703-487-4650).
1. "Fine Pore Diffuser System Evaluation for the Green Bay Metropolitan
Sewerage District" (EPA/600/R-94/093) by J.J. Marx
2. "Oxygen Transfer Efficiency Surveys at the Jones Island Treatment
Plants, 1985-1988" (EPA/600/R-94/094) by R. Warriner
3. "Fine Pore Diffuser Fouling: The Los Angeles Studies"
(EPA/600/R-94/095) by M.K. Stenstrom and G. Masutani
4. "Oxygen Transfer Studies at the Madison Metropolitan Sewerage District
Facilities" (EPA/600/R-94/096) by W.C. Boyle, A. Craven, W. Danley, and
M. Rieth
5. "Long Term Performance Characteristics of Fine Pore Ceramic
Diffusers at Monroe, Wisconsin" (EPA/600/R-94/097) by D.T. Redmon, L.
Ewing, H. Melcer, and G.V. Ellefson
6. "Case History of Fine Pore Diffuser Retrofit at Ridgewood, New Jersey"
(EPA/600/R-94/098) by J.A. Mueller and P.O. Saurer
7. "Oxygen Transfer Efficiency Surveys at the South Shore Wastewater
Treatment Plant, 1985-1987" (EPA/600/R-94/099) by R. Warriner
8. "Fine Pore Diffuser Case History for Frankenmuth, Michigan"
(EPA/600/R-94/100) by T.A. Allbaugh and S.J. Kang
iv
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9. "Off-gas Analysis Results and Fine Pore Retrofit Information for
Glastonbury, Connecticut" (EPA/600/R-94/101) by R.G. Gilbert and R.C.
Sullivan
10. "Off-Gas Analysis Results and Fine Pore Retrofit Case History for
Hartford, Connecticut" (EPA/600/R-94/105) by R.G. Gilbert and R.C.
Sullivan
11. "The Measurement and Control of Fouling in Fine Pore Diffuser Systems"
(EPA/600/R-94/102) by E.L. Barnhart and M. Collins
12. "Fouling of Fine Pore Diffused Aerators: An Interplant Comparison"
(EPA/600/R-94/103) by C.R. Baillod and K. Hopkins
13. "Case History Report on Milwaukee Ceramic Plate Aeration Facilities"
(EPA/600/R-94/106) by L.A. Ernest
14. "Survey and Evaluation of Porous Polyethylene Media Fine Bubble Tube and
Disk Aerators" (EPA/600/R-94/104) by D.H. Houck
15. "Investigations into Biofouling Phenomena in Fine Pore Aeration Devices"
(EPA/600/R-94/107) by W. Jansen, J.W. Costerton, and H. Melcer
16. "Characterization of Clean and Fouled Perforated Membrane Diffusers"
(EPA/600/R-94/108) by Ewing Engineering Co.
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ABSTRACT
Ceramic plate dlffusers were among the earliest forms of fine pore
diffusers used for oxygen transfer in activated sludge treatment. They have
been successfully used for over 60 years in the Jones Island West Plant of the
Milwaukee Metropolitan Sewerage District and, since initial start-up, in the
Jones Island East Plant and the South Shore Plant. Surveys of performance of
these diffusers in all three plants were included in the EPA/ASCE Fine Pore
Aeration Project. This report presents the results of 20 off-gas sampling
surveys carried out at the South Shore Wastewater Treatment Plant.
For all 20 basin surveys, the median value of standardized oxygen
transfer efficientcy (alpha-F-SOTE) was 18.9%. When evidence of nitrification
was present, alpha-F-SOTE values were higher than on other survey dates.
A cleaning history for the basin was obtained at the time of each off-gas
survey. However, no correlation between number of months in service since
cleaning and alpha-F-SOTE could be identified.
This report was submitted in partial fulfillment of Cooperative Agreement
No. CR812167 by the American Society of Civil Engineers under subcontract to
the Milwaukee Metropolitan Sewerage District under the partial sponsorship of
the U.S. Environmental Protection Agency. The work reported herein was
conducted over the period of 1985-1987.
vi
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CONTENTS
Foreword
Preface
Abstract
Preface . . ............................. . ..................... ........ iv
'''''''''
....................... . ....................... •......... vi
Figures ...... ........................................... '.'.'.','.'.'.'.'.'.'. viii
Tables; ...................... . .............................. '.'.'.'.'.'.'.'. viii
Acknowledgements ............................................ ..... . . . . \x
1 . Introduction ........................... . ................... ......... 1
2. Conclusions ............... .................................. '..'.'.'.'.'. 2
3. Plant Description ........................................... '.'.'.'.'.'.'.'.'. 3
4. Conduct of the Surveys ...................................... ......... 5
Off:Gas Survey Methods .............................. .............. 5
Aeration Basin Operation ................................... ......... 6
Treatment Plant Operation ..... . ......................... ........... 7
Presentation of Survey Data ................................ . . ....... \ 7
5. Survey Results ............................................ ...... " ' 9
Diurnal Study ........................................... ....... [\ 9
Collection Hood Orientation .......................................... 9
6. Discussion ................................................. ...'.'.'.'.'. 15
References ................................ ........................ -\ j
Appendices ...... '
A. Overall Plant Data Form .... ....................................... 18
B. Additional Plant Operation Data ........ . .......... . . .......... ....... 26
VII
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Number
Number
FIGURES
Page
1 Plan and Cross Section View of a South Shore
Aeration Basin ..... 4
2 Report Format Used for Off-Gas Survey Data ...... 8
3 Sample Profiles for Dissolved Oxygen and Oxygen
Transfer Efficiency 12
4 Diurnal Test Results for South Shore Tank 12 on
July 22 and 23, 1986 13
TABLES
Page
1 Summary of Oxygen Transfer Survey Data 10
2 Secondary Treatment Nitrogen Data ! ! 11
3 Results From the Hood Position Study . ! ! ! 14
VIII
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ACKNOWLEDGEMENTS
The involvement of engineering co-op students from Marquette University
and the University of Wisconsin - Milwaukee was indispensable for this
project. They are (in chronological order of participation): Robert
Dumke, Michael Mitchell, Tom Raasch, and Rockne Elgin. Their assistance
is gratefully acknowledged.
Joseph Grinker, Process Control Supervisor, for the South Shore Plant
gave valuable guidance and support to the project. The initial impetus
for the project came from Larry Ernest, who at that time was Manager of
Laboratory Services. Thanks are in order to him and to Lloyd Ewing and
Dave Redmon of Ewing Engineering Company for continuing guidance and
support.
IX
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INTRODUCTION
Ceramic plate diffusers, such as those in service at Milwaukee's South
Shore Wastewater Treatment Plant, were among the earliest forms of fine
pore diffusers used in activated sludge treatment. They have been
successfully used for periods of up to fifty years in one of the treat-
ment plants of the Milwaukee Metropolitan Sewerage District (MMSD).
Because of this record, surveys of current performance of these
diffusers in all three activated sludge plants operated by the MMSD were
included in the EPA/ASCE Fine Pore Diffuser Project. This report
presents the results of surveys carried out at the South Shore Plant.
The program was planned to include twenty surveys of South Shore Plant
basins. Originally, each of five basins was to be tested'four times
over a two year period. Unfortunately, at the start of testing, the
requirements of an ongoing program of rehabilitation and expansion at
the Plant necessitated taking each battery out of service for three to
four months in succession. The tank surveys were grouped by season,
viz., six in Summer, 1985* six in Fall, 1985, four in Summer, 1986, and
four in Spring, 1987. Only two basins could be tested on all four
occasions; the selection of the remainder was dictated largely by
availability of pairs of basins in normal service.
Following the April, 1986 Contractors' meeting, two additional surveys
were added to the program. The first was a one-time investigation of
the effects of collection hood placement patterns on observed oxygen
transfer efficiency. The second was a 24 hour survey with hourly OTE
observations for two hood stations in basin No. 12.
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CONCLUSIONS
1. The flux weighted alpha-F-SOTE values obtained from 20 South Shore
aeration basin surveys ranged from 15.0% to 22;2% with a mean value
of 18.9%.
2. The mean sludge age for the South Shore Treatment Plant for the 10
test days in the study period was 6.8 days. The mean F/M ratio was
0.37 days . Testing at the lower sludge ages (4-6 days) yielded
lower estimates of alpha-F-SOTE (15-18%).
3. For survey dates when there was evidence of nitrification, as
measured by final effluent ammonia, nitrite, and nitrate
concentrations, alpha-F-SOTE values were higher than on the other
survey dates.
4. A diurnal OTE survey at the South Shore Plant showed'no significant
shift in alpha-F-SOTE for the collection hood positions used in the
survey (at approximately the 2/3 point of tank length).
5. Flux-weighted alpha-F-SOTE values were unrelated to the number of
months in service following the last previous high pressure hosing
or hosing plus acid cleaning.
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PLANT DESCRIPTION
The MMSD's South Shore Wastewater Treatment Plant began activated sludge
treatment in 1974. There are twenty-four aeration basins arranged in
four batteries of six basins each. They are 370 feet long, 30 feet
wide, with a water depth of 15 feet. The width at the water surface is
approximately 26 feet because of Y-wall construction used to accommodate
the process air mains and primary effluent step feed as well as to
provide walkways between tanks. Figure 1 shows a plan view and a
cross-section of a basin.
The tanks are flat bottom with one foot square, 1-1/2 inch thick ceramic
(silica) diffuser plates in 9-plate containers arranged in a
longitudinal pattern so that the plates are flush with the floor of the
tank. Process air piping to the containers is arranged beneath the tank
floor. Containers are placed across the width of the tank in a
staggered pattern, eight across. Each downcomer supplies two rows of
eight containers or 144 plates. With 17 downcomers, the total number of
plates per tank is 2,448. The permeabilities range from 15 to 21. The
plates are grouped by permeabilities in ranges of 15-16, 17-19, and
20-21. Each downcomer is fitted with plates of only one range. Return
sludge is fed at the head of each tank. Primary effluent is added at
the head of the tank and at step feed points on both sides of the tank
at approximately the quarter and the halfway points along the length.
More detailed information concerning the historical record, aeration
basin and process air supply design, and plant operation and maintenance
are presented in the Report on South Shore Plant History prepared by
Larry Ernest under this EPA contract (1).
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South Shore Tank 19
-22
370
•87-
22-1
(tip.)]
Process Air
Domconer
.&.
Flo*
.V
.93.
Scale: F—H = 10 ft.
Test Plenun
Plan ?ier
\ L
Retim Sludge
Addition
Prinary Effluent
Addition :
i
4.5
15.9
South Shore Tank.
-25.0-
\1
18.7
11.D
•30.0-
Scale:
End Vier
- 10 ft.
Figure 1. Plan and cross section views of an original South Shore
aeration basin.
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CONDUCT OF THE SURVEYS
OFF GAS SURVEY METHODS
The MMSD purchased an "Aerator-Rator, Mark IV" off-gas analyzer from
Ewing Engineering Company in June, 1985. This provided the opportunity
to use the off-gas method for measurement of oxygen transfer efficiency
as described by Redmon, et al. (2). The off-gas monitoring unit was
used with two gas collection hoods, designed and built by Ewing
Engineering Company. The hoods, constructed of fiber glass and PVC pipe
reinforcing, each had a collection area of dimensions 2 feet by 16.5
feet or 33 square feet. The volume under the hood was approximately
30 cubic feet and depended on the hood position in the mixed liquor.
The connection between each hood and the Aerator-Rator was made with 50
feet of 1-1/4 inch vacuum cleaner hose.
Carbon dioxide content in the off-gas was measured using a Dwyer C0?
indicator. The Aerator-Rator came equipped with a drying column, so
humidity data were not collected for either off-gas or reference air.
At least two gas samples were collected for C02 determination for every
collection hood position. Mixed liquor dissolved oxygen concentration
was also measured at every collection hood station using YSI dissolved
oxygen meters and field probes. Readings were taken at depths of
approximately four feet and ten feet and averaged. These, two readings
rarely varied by more than 0.1 mg/1.
Before a survey was begun, twelve test stations were located at equal
distances along the length of the tank to be tested. With a hood
collecting off-gas from 33 square feet at each station, the total area
sampled was 396 square feet or 4.3 percent of tank surface area. For
the South Shore surveys, all basins were tested in pairs with one
collecting hood in each basin and the Aerator-Rator set up between
basins. Stations were sampled in sequence from the inlet to the outlet.
At each station, the hood was positioned lengthwise across the width of
the tank, approximately in the center, and secured with ropes. As soon
as a station was sampled, the hood was moved to the next location while
a measurement was completed for the adjacent tank.
The traverse from inlet to outlet for a pair of basins usually required
6 hours. The average time on a station was 15 minutes, with the oxygen
sensor millivolt output recorded for the latter half of that period.
After data for a station were recorded, the hood was moved immediately
to the next station where about 20 minutes elapsed before off-gas
readings were taken.
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The lowest air flow tested was 1,300 scfm or an average flux rate of
0.14 scfm/sq. ft. This would yield an off-gas collection rate of 4.6
scfm, and a residence time for the off-gas in the hood of about seven
minutes. Thus, approximately three residence times elapsed between
set-up of the collection hood and recording of the off-gas millivolt
output. Higher air flows provided additional flow-through before
readings were taken. These readings were recorded at one minute inter-
vals, and the data were accepted when 4 readings had been obtained with
a range not exceeding 4 millivolts.
AERATION BASIN OPERATION
In normal operation, the air flow is controlled by a central computer
responding to a dissolved oxygen concentration reading obtained near the
effluent end of the tank. During 1985, the test basins were left on
computer control in order to represent normal operation. This typically
resulted in airflow variation of plus or minus 20 to 30 percent. For
the 1986 surveys, the air flow valves to the test basins were controlled
locally, and the air flow variation was held between 5 and 10 percent of
the mean air flow for the survey.
The 17 downcomers are equipped with knife gate values requiring manual
adjustment. These were not adjusted during the surveys. , At times.
Operations Staff had set the valves for most basins to provide positive
dissolved oxygen readings over as much of the basin length as possible.
These were, of course, settings related to the air flow and loadings
occurring at the time of the adjustments. It was not feasible to relate
airflows to the downcomers during these surveys except to note.that a
great variety of dissolved oxygen profiles was observed, and measured
flux rates varied widely along most tanks.
For basins in service, valves controlling primary effluent addition were
normally fully open, so that flow variation reflected variation in flow
to the entire plant. The South Shore aeration basins were operated in
the step-feed mode during the entire period covered in this testing
program. About a third of the primary effluent was added at the head of
the tank, a third at the one-quarter point, and a third at the half-way
point. The valves regulating return sludge flow to the basins were
under computer control with the objective of maintaining desired mixed
liquor solids concentrations. These valves were left on computer
control during all surveys. Changes were usually gradual and within a
20% range from lowest readings to the highest for both primary effluent
and return sludge flows.
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TREATMENT PLANT OPERATION
Measurements of primary effluent 5 day BOD, mixed liquor suspended
solids, sludge wasting rates, and sludge solids inventories were ob-
tained from plant monthly reports that provided analytical data from
24-hour composite samples and operations data based on the same 24-hour
periods. The BOD sample was collected from the flow to the entire plant
while the remaining values were obtained for the battery that included
the tanks surveyed.
Nitrogen related measurements were all compiled from plant monthly
reports and based upon 24 hour composite samples of primary effluent and
final effluent.
PRESENTATION OF'SURVEY DATA
Survey data were recorded on the "Offgas Field Data Sheet" (3). The
value of beta, the ratio of the saturation oxygen concentration in
process water to that in clean water, was assumed to be 0.99 throughout
the South Shore Plant testing. A value of 10.6 mg/1 was selected for
the clean water dissolved oxygen saturation concentration at 20° C for a
15 foot deep aeration basin equipped with fine pore diffusers (4). An
effective saturation depth of 43% of submergence was assumed in obtain-
ing the pressure correction factor used to calculate the field dissolved
oxygen saturation value and the deficit or driving force at each
station.
A FORTRAN program was written to accept the data obtained from an
off-gas survey, complete the required calculations, and print a report
displaying the data and the calculated efficiencies for each station as
well as flux weighted values for the field efficiency (FOTE) and the
standardized efficiency for a dissolved oxygen concentration of zero
(alpha-F-SOTE). Figure 2 is an illustration of a survey summary report
using Tank 20 on July 26, 1985, as an example.
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SURVEY RESULTS
Twenty surveys were completed for the South Shore Plant. Table 1 is an
overall summary of test dates, test conditions, and flux weighted
average field and standard OTE values. Also shown are tank cleaning
information, sludge age and loading estimates for the test dates. Table
2 contains nitrogen related data taken from plant laboratory records for
the ten test dates. Detailed information concerning treatment plant
facilities and operation are included in the Overall Plant Data Sheet
(Appendix A) and in the monthly averages of data for South Shore primary
effluent and South Shore activated sludge basins that were compiled in
connection with the EPA/ASCE Interplant Fouling Study (Appendix B).
Figure 3 shows the profiles obtained from the first pair of surveys for
this project. The average air flow for tank 13 was 2600 scfm, and for
tank 14 it was 1500 scfm. This difference is reflected in the lower
dissolved oxygen measured in tank 14. The basins had nearly the-same
average standard efficiency, 19.4 percent for tank 13 and 18.8 percent
for tank 14.
DIURNAL STUDY
The results of a diurnal test for 2 stations located in tank 12 are
shown in Figure 4. The test ran from noon on July 22, to noon on
July 23, 1986. The air flow to the basin was controlled manually at
1900 scfm plus or minus 10 percent. Dissolved oxygen profiles were
similar for the 2 stations with an unexplained peak occurring at both
stations at about 6 p.m. FOTE values were higher at station 7 than
station 8, possibly reflecting a decrease in the BOD load between
stations since both stations were beyond the second step-feed point and
plant data gave no indication of nitrification.
No explanation is at hand for the decrease in alpha-F-SOTE between
station 7 and station 8. In any event, alpha-F-SOTE varied less than 10
percent at either position, indicating little or no variation in alpha
with clock time for those stations on that date.
COLLECTION HOOD ORIENTATION
A study of the effects of hood placement on weighted average OTE and
off-gas flux was carried out on July 15, 1986. Since South Shore
aeration basins had Y-wall construction along the entire length, it
appeared that flux rates at the edge could exceed those at the center,
because flow patterns for the rising bubbles might cause a build-up
under the Y-wall.
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10
-------
Table 2
Secondary Treatment Nitrogen Data
South
Shore Wastewater
July, 1985
Primary
TKN
34
31
34
24
27
24
15
24
16
Effluent
NH3
26
20
23
36
15
21
15
9
-
- —
- April
Treatment PI
, 1987
(1)
ant
Final Effluent
TKN
8
6
4
20
13
16
13
10
15
9
NH3
7
_
4
20
11
14
11
8
-
_
N02
0.7
1.0
0.5
0.2
0.8
1.0
0.7
0.7
0.1
0.3
,N03
.7.8
6.1
11.0
0.7
.1.9
2.5
2.1
1.4
0.2
0.7
Date
7/24/85
7/26/85
7/29/85
10/17/85
10/28/85
10/31/85
7/24/86
7/28/86
3/20/87
4/17/87
(1) All values in mg/1; (-) denotes missing value.
11
-------
SOUTH SHORE TANK 13
TESTED ON JULY 24,1985
U
I
0.26-
0.20-
0.1B-
0.10-
0.06-
laTStandird Efficiency)!
A A-
Oxyo«n|
PRIMARY EFFLUENT
~ ADDITION POINTS ~
0.00
i.
I»
0 10 20 30 40 50 60 70 80 90 100 110 °
Tank Length (meters)
SOUTH SHORE TANK 14
TESTED ON JULY 24,1985
0.26-1
0.20-
u
£
o.io-
0.08-
0.00
I oKStandard Efflclancy)|
|DI»8olvad Oxyganj
.PHIMABY EFFLUENT
ADOmON POINTS
•A A -A"
0 10 20 30 40 50 60 70 80 90 100 110
hi >
o
05
Tank Length (meters)
Figure 3. Profiles for dissolved oxygen, FOTE, and alpha-F-SOTE for
basins 13 and 14 surveyed on July 24, 1985.
12
-------
0.20-.
0.16-
I
0.10-
0,09-
0.00
0
Noon
\
\
SOUTH SHORE
DIURNAL STUDY
TANK 12 STATION?
LEGEND
D STANDAHD EFFICIENCY
O FIELD EFFICIENCY
A DISSOLVED OXYGEN
A
\
\
A
/
A
10 12 14 16
Run Time (Hours)
18 20 22
-1.6
-1
^
J
I
-0.6 g
24 20
Noon
0.20-I
0.18-
0.10-
0.06-
0.00
**<***
*\
SOUTH SHORE
DIURNAL STUDY
TANK 12 STATIONS
LEGEND
D STANDARD EFFICIENCY
O HELD EFFICIENCY
A DISSOLVED OXYGEN
024
Neon
10 12 14 16
Run Time (Hours)
18 20 22
r2
I
I
g
jo
a
24 26
Noon
Figure 4. Diurnal test results for South Shore tank 12 on July 22
and 23, 1986.
13
-------
A survey was carried out with 2 collection hoods in Basin 12. One hood
was placed lengthwise along the east edge of the basin while the other
was placed across the width of the tank at the usual test positions.
The air flow was maintained manually during the survey at: 1100 scfm plus
or minus 10 percent. The 12 edge positions were lined up as nearly as
possible so that the hood in the edge position formed a "T" with the
hood in the cross-tank position. The average results from this compari-
son survey are shown in Table 3.
Table 3
Average Results for the Hood Position Study
South Shore Wastewater Treatment Plant
alpha-F-SOTE Flux Rate
Hood Position . % scfm/sq ft
Across the tank in the center 13.6 0.107
Longitudinally along east edge * 12.6 ... 0.113
The results of this exercise showed no significant difference between
the edge and center hood for average flux or for flux weighted average
alpha-F-SOTE. At any given distance along the tank, however, there were
large differences between the center and edge values for both flux and
alpha-F-SOTE.
14
-------
DISCUSSION
The standardized oxygen transfer efficiency under process conditions
(alpha-F-SOTE) has been proposed by the ASCE oxygen transfer committee
for characterizing performance of aeration basins equipped with fine
pore diffusers (5). SOTE refers to clean water performance which is
unknown in this case. Alpha is the ratio of oxygen transfer rate under
process conditions to that in clean water. With time, diffusers operat-
ing under process conditions may suffer fouling and loss of efficiency.
This effect is incorporated in the modified transfer efficiency term,
alpha-F-SOTE.
The average value of alpha-F-SOTE for all 20 South Shore surveys was
18.9% with a range of 15.0 to 22.2%. For the South Shore tanks the
average efficiency per meter of depth was 4.4%, a very high value in
comparison with the values in the interim data base presented by Brenner
and Boyle (5).
Among the operating variables presented in Table 1, sludge age varied
from 2.7 days to 12 days, air flow from 1300 scfm (0.53 scfm/diffuser)
and 2600 scfm (1.06 scfm/diffuser), and time in service since previous
cleaning from 6 months to nearly 5 years. The influence of these
variables on alpha-F-SOTE was examined by applying stepwise multiple
regression. With a 5% level of significance, neither air flow nor time
in service could be included in the final equation. The influence of
sludge age was significant at the 5 percent level; however, it is
important to note that wide daily variations occur in sludge age both on
a plant basis and a battery basis. While the average sludge age of 7.5
days for 10 survey dates is probably a useful estimate of sludge age for
the 20 month period over which OTE surveys were conducted, any indi-
vidual daily value can be greatly affected by requirements of plant
operations. An obvious example is temporary cessation of sludge wasting
which produces a high, but not meaningful, value of sludge age for that
day.
Maintenance of a South Shore aeration basin consists of taking the basin
out of service, draining it, and flushing the bottom and sides using a
high pressure hose. Occasionally, 50 percent muriatic acid is applied
to the diffusers followed by a second rinsing of the basin floor with
the high pressure hose. These procedures have been used when the
operator is unable to maintain a desired air flow to the basin at the
header pressure for the plant or they have been required by
circumstances unrelated to aeration basin performance (e.g., taking
basins in and out of service to accommodate contractors participating in
plant expansion and upgrading). As expected, no relationship was found
between efficiency and time in service since cleaning. <.
15
-------
From Table 2, it appears that nitrification was taking place during
July, 1985 when 6 of the OTE surveys were made. The mean value of
alpha-F-SOTE was 20.6% while the mean value for the remaining 14 surveys
was 18.2%. While this represented only about a 10% difference - close
to the experimental error in the measurement of alpha-F-SOTE - it was
consistent with the findings summarized in the status report of Brenner
and Boyle that showed higher values of alpha-F-SOTE associated with
nitrifying as opposed to non-nitrifying systems.
16
-------
REFERENCES
1. . Ernest, L. A. Case History Report on Milwaukee Ceramic Plate
Aeration Facilities. Study conducted under Cooperative Agreement
CR812167, Risk Reduction Engineering Laboratory, U.S. E.P.A.,
Cincinnati, OH (to be published).
2. Redmon, D. T., W. C. Boyle and L. Ewing. Oxygen Transfer Effi-
ciency Measurements in Mixed Liquor Using Off-Gas Techniques.
Journal WPCF, 55(11): 1338-1347, November, 1983.
3. Cooperative Agreement CR812167, Risk Reduction Laboratory, U.S.
E.P.A., Cincinnati, OH: Manual of Methods for Fine Bubble Diffused
Aeration Field Studies, Appendix A, July, 1985.
4. Personal communication from David T. Redmon, Ewing Engineering Co.,
Milwaukee, WI, September 27, 1985. ;
5. Brenner, R. C. and W. C. Boyle. Status of Fine Pore Aeration in
the United States. In: Proceedings of the llth United
States/Japan Conference on Sewage Treatment Technology, EPA
600/9-88/010, NTIS No. PB88-214986, U.S. E.P.A., Cincinnati, OH,
April, 1988.
17
-------
APP&iilX A
Plant Name. . .
Section No. Al.O
ROT is ion No. 0
Date 7/23/85
Page 7 of 13
EXHIBIT A.I: OVEHALL PLANT DATA SHEET
BASED ON PREVIOUS TEAR OF RECORD
South Shore Wastewater
.SUlt ......... Location. .Q3.^ .Creek,. X,U««15iQ . . . .
Secondary Treatment: Average.........MGD Has.Day.. MGD
WASTEWATER CHARACTERISTICS- BASED ON MONTHLY. AVERAGES
- . 15 „. 10.5
5 day BOD
COD (opt)
TSS
IBS **
TEN
Total P
pfl (sot mg/1)
Alkalinity*
Hardness*
Nitrate-N
Raw Influent mg^
Av« Min
153 90
. _ _ _
213 124
835 697
30 17
4.6 2.7
7.8 7.4
—
fl
Max
226
306
954
47
5.9
..§;9..
—
Sac. Effl. mg/1
Ave Mia
13.9
808
3.5
.,12... ..12,..
6.3
709
.-.6.9.. ...-.4.5.
J...2. ..7. P.
.26
Max
. .?-.
25
922.
•as calcium carbonate equivalent
** For 7 years: 1975-1981
18
-------
Section Al.O
Err ision No. 0
Dat» 7/23/85
Page 8 of 13
PIZOCESS FLOW DIAG8AK INCLUDING TANZ SIZES AND EETUSN FLOWS FBDM SLUDGE PEDC
16@ 2 • V
Primary S.d. Area. «q ft.^QO. Ft.... Fittil CUr. ^.^ sq ft!6.@. 10^39.2
240 2
A»r»ti
t
Chlortn. ConUcI
ChjmtMr
«.-
s*~r~ ^
f Likt Mtetilgm
SOI
WASTEW/
JTH SHORE
kTER TREATMENT
PLANT
A
»^M!I
' Thlck«nln9
Wnt* ActtvtM Studo*
(35 *T«
o j-a.5 r,o
Oewi
and S
t
^> ^ LandlHI
•rinq
torn soo.oee
t
Land
ApplfcMfon
'
Primiry .
pntt
309.000 Q-'O I I90drylofl»
Digested Sludoe
rG^,» Twk* '
t
Ol9*«tw G*i
MSCFD
IS dry tocn/«cy 50 dry
(125 eu. vtft.) (SM cti.
1UUOE INDUSTRIAL WASTES- Averages
Glue
Machinery, including plating
Food
Tanning
Landfill (Leachate)
.Flow
3.1
.Flow
2.0
.Flow
0.7
.Flow.
0.2
Flow
0.1
.JCD
.JCD
.JCS
BOD.
BOD.
BOD.
BOD.
BOD.
460
80
1160
1430
2300
.aw/1
.aw/1
.aw/1
.aw/1
,aw/i
19
-------
Section No. Al.O
Revision No. 0
Date 7/23/85
Page 9 of 13
RETURN FLOWS FROM SLUDGE PROCESSING- Averages
Source Flo* MGD BOD mg/1 TSS mg/1 TEN mg/1 pfl
Incinerator
Recycle .05-.10
DAF underflow 1.0 (.7-1.4)
No teat:
PRIMAEZ EFFLUENT CHARACTERISTICS- AVERAGE INCLUDING RETURN FLOWS
96 97 73 27
Flo» HGD BOD ag/1 TSS ag/1 TEN ag/1
Total Raw Influent ,,-
TDS ...ag/1 SralXana Grease -«..mg/l COD..200 mg/l
PROCESS PARAMETERS- Based on Average Conditions +/- percent variability
max. month to ain. month
Mi n. Max.
__ ., ., . ^< 797 -1759
Primary Overflow Rate, gpd/sf....
48 34 64
Aeration Detention Tiae, 7/Q '. * ......
HLSS Concentration ag/1..., A7.3.0... 140° .?1.°P.
.73 .68 .77
Ratio, MLVSS/MLSS
352,000 282,000 412,000
HLSS Inventory lb*
« ,.* « * . ^ ««,«,/, 59,648 37,947 108,587
Solids Wasting Rate, Ib HLSS/day .........
«, , TT , 235 117 396
Sludge Volume Index .....
Recycle Ratio, R/Q -.3.9. >23 .;.4.6.
20 '
-------
Section No. Al.O
Revision No. 0
Date 7/23/85
Page 10 of 13 Avg. Max Min
Sludg* Age, Days- ?•85. ...11.0 4.9
F/M Ratio. p« .Law* .QClfice for. 9.
is one inch diameter.
Clean Diffuser, inches water ^_^_^ ............ ...........
^ These data unavailable for South Shore.
Dirty Diffuser* inches water •""'^ ............ ...........
(if available)
1974 15 15
Tuar Installed. . ...... Submergence, ft ........... Vater Depth, ft ......
Cleaning Practice and History: ...Rlaase.Sefi..tha .plant ,bistocy.repor±..
Sitetch of Diffuser Arrangement in Tank. Give Essential Dimensions for
Diffuser Spacing and Air Distribution Piping. Indicate Tapering.
Begin vith Downcoaer.
Please see the South Shore Plant History Report by Larry Ernest,
21
-------
Suction Al.O
lev ision No. 0
Date 7/23/85
Page 11 of 13
BL01EBS AND AIS. SUPPLT PIPING
Blower
Nrmber
^••MM
1
2
3
4
5
6
Include the Biting Curve for Each Blower if Available
SEE ATTACHMENT
Describe the Air Filtration Systea:
Inlet air to the aeration system is filtered through a Fuller Company ATMOS
Filter System. These non-abestos bag type filters have a rated design capacity
of 200,000 cfm. The filters are equipped with a shaker cleaning mechanism.
Type, Brand. Model leaz HP RPM
Allis-rChalmers Single Stage
Centrifugal Compressors 1375 900
11
11
n
Installed Blower HP SCFH
SCFM
35000
35QPP.
35000
35000
_
Op. Time
Sr/Iear
3294
694
3686
3307
Supplemental Information on Blower Drive*
Drive
Nnaber
1
2
3
4
5
6
Drive Type, Brand. Model Tear
Bhite Superior 12 Cylinder
ual Gas Engine 1973
1973
1973
1973
Design
SPK
900
900
900 .
900
HP at Design EPM
U3.7.5...
1,375
1,375
1,375
22
-------
IU
£
> u.
W ^
OC »-
O H
W <
-------
Section No. Al.O
Eerision No. 0
Date 7/23/85
Pago 12 of 13
Typical Blowers Deed at Average Operating Conditions:
Blower Nuabers .................. Total Horsepower
Measured Pressure at Blower Discharge, psi.
7.5-8.0
Measured Dynastic »et Pressure at Diffuser. psi.
1.0
Noainal SCFM per Diffuser..
Typical Blowers Used at Maxiaum Operating Conditions:
Blower Nuabers ? Totml Horsepower 275Q
Measured Pressure at Blower Discharge, psi................
Nomiaal SCFM per Diffuser .V.Q
Describe Blower Turndown Capability
Describe Strategy Used to Manage Blowers ---- & J. pfe.S.e/Xt.,. JVWS&l .<
. . te.lPW 4ft5lga .levels , . . . One. blp.v«y: .is .oftgn. suf f ic.i.e.nt i. .A .s.e.cqijd .bl Qw?r
. . . JS. MdM jftteaewc.besjler. JVASliiKe .f§ll§..b.eJp.w. A Ars,d.e.t.e.r3ni.aed .level , .
* Sketch Showing the Arrangeaent of Blowers and Traxtsaissiou Piping.
If possible. Snow Sufficient Detail so that Friction Loss Calculations Could
be Made. Snow Pipe Sizes. Lengths. Control Valres and Number of Bends from
the Blowers to' the Aeration Tanks.
Please see page 25.
24
-------
Section No. Al.O
K.«Ti»iem No. 0
Date 7/23/85
Page 13 of 13
Describe tie Data Base for Aeration Tank Dissolved Oxygen:
Frequency of Mea«ure»»nt. Jlinaa Ma4^ j!Qt§ryalsr:as. part. of. compute^ control loop,
Number of Locations ...... Djlfi. 4ir.QJte At .t3Qk.QUt]et, ............ ..........
L«agth of Eecord ........................ . ....... ...... ........
Typical Aeration Tank D.O. Values (From 1985 Off-Gas OTE Testing)
M*xis8» Miaixuv Avg. (8 tanks)
First auart.r . . '61 *27 l'27
secou
Ttird ....
Fourth Quarter .. I'.4.0. . . . . . . .V.9.? . . . . . ...?:!5
RESULTS OF P2EV10US OET0EN ISANSFEE 1ESTS AT THIS PLANT . Three. part1al tank
were. .cAr.*:\s4 •Q'it .^.QSY?.??^?.". .°.f. .E.win.9 ,lQgl!???nPF. ?P. Pf ?.°.b.e.r.». ,1.9.8.1.-. . J.h.e. ,f.01 ] Ow1n9
values for alpha'SOTE were obtained: Tank 16, U.8%; *Tank*i*9*," iV.VxV" TanV*21, 21.7%
-a
hS
•-Q -Q
•IW.6T GUIDE
VANE (TYP)
VENT
(TVP)
OUTSIDE WALL
AERATION BASIN
HEADER 1TVP) •
A-
tlb
WT AIR HEADER
EXISTtNO ACRATKM '
BASIN SATTERV (TVP)
-€«•«.-
COMMON WALL
AERATION 8ASIM
MEADCR (TYP)
-Tar •fur r»- »•«
FIGURE 1
EXISTING AIR SUPPLY
SYSTEM SCHEMATIC
25
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