CASE HISTORY REPORT ON MILWAUKEE
CERAMIC PLATE AERATION FACILITIES
by
Lawrence A. Ernest
5955 N. Lake Drive
Milwaukee, Wisconsin 53217
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
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
iii
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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
9. "Off-gas Analysis Results and Fine Pore Retrofit Information for Glastonbury, Connecticut"
(EPA/600/R-94/101)byR.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
IV
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11. The Measurement and Control of Fouling in Fine Pore Diffuser Systems"
(EPA/600/R-94/102) by E.L. Bamhart 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/60Q/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 diffusers were among the earliest forms of fine pore diffusers
used in activated sludge treatment. They have successfully used for over 60
years in the Jones Island West Plant of the Milwaukee Metropolitan Sewerage
District (MMSD) and since 1935 and 1974, respectively, in the MMSD Jones Island
East and MMSD South Shore Plants. The Jones Island East Plant aeration basins
were completely rehabilitated in 1982-1983, and the West Plant basins were
scheduled for rehabilitation in 1989-1990. In both cases, alternative fine pore
systems were evaluated and ceramic plate diffusers were again selected. Three
separate case history reviews are presented: the Jones Island East Plant, the
Jones Island West Plant, and the South Shore Plant. The Jones Island East Plant
case history is divided into two separate reports: one covering the period of
1930-1981 and the other the period of 1982-1988. All of the historical reviews
discuss the conceptual designs and selection process involved for each of the
plants.
The four reports covering the above three case histories have been kept in
their original form and are presented herein in chronological order as follow:
1. Milwaukee, Wisconsin Jones Island West Plant Aeration History, 1915-1982
2. Milwaukee, Wisconsin Jones Island East Plant or Extension Aeration History,
1930-1981
3. Milwaukee, Wisconsin South Shore Wastewater Treatment Plant Aeration History,
1974-1988
4. Milwaukee, Wisconsin Jones Island East Plant Aeration Tank Renovation
History, 1982-1988
The major sources for the information from 1915 through 1974 came from the
First through Sixty-First Annual Reports of the Sewerage Commission of the City
of Milwaukee and from the existing Milwaukee Metropolitan Sewerage District.
Direct quotations are taken from the documents on file with the District. Other
sources of background information are cited in the reports.
This report was submitted in partial fulfillment of Cooperative Agreement
No. CR812167 by the American Society of Civil Engineers under subcontract to Mr.
Lawrence A. Ernest under the partial sponsorship of the U.S. Environmental
Protection Agency. The work report herein was conducted over the period of 1986-
1989.
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TABLE OF CONTENTS
Foreword i^
Preface ' ' 31
Abstract , v
Figures ' ^v
Tables . . '.'.'.'.'.'' ' ' ' 1?
Acknowledgements ! xii
MILWAUKEE, WISCONSIN JONES ISLAND WEST PLANT
AERATION, 1915-1982 r
INTRODUCTION ' }
PLANT DESIGN ' ' ' ' \
AERATION PLANT START-UP EXPERIENCE 1925-i93o' .' .* 13
AERATION TANK FOULING PROBLEMS AND PLATE CHANGES . '. 13
AERATION TANK CLEANING ' ' ' 14
AIR SUPPLIED TO AERATION SYSTEM 18
MILWAUKEE EXPERIENCE WITH POROUS PLATE ' ' '
DIFFUSERS 1913-1982 21
WEST PLANT PERFORMANCE 1927-1981 " ' '
MILWAUKEE, WISCONSIN JONES ISLAND EAST PLANT
OR EXTENSION AERATION HISTORY, 1930-1981 .... 29
INTRODUCTION ' ' ' ?l
PLANT EXTENSION ' ' ' ||
AERATION TANK CLEANING . ' 44
AIR SUPPLIED TO AERATION SYSTEM .' .' ' 47
CHANGES IN AIR DISTRIBUTION 40
EAST PLANT PERFORMANCE . 40
MILWAUKEE, WISCONSIN SOUTH SHORE WASTEWATER ' ' '-' "-' -'-' * ' ' " '
TREATMENT PLANT AERATION HISTORY, 1974-1988 ... 55
INTRODUCTION II
AERATION TANKS .......!' «
PROCESS AIR SUPPLY ' ' ' en
FACILITY EXPANSION 63
PLANT PERFORMANCE 1978-1987 ............ «|
MILWAUKEE, WISCONSIN JONES ISLAND EAST PLANT ' * " '
AERATION TANK RENOVATION HISTORY, 1982-1988 ... 71
INTRODUCTION 7}
NEW EAST PLANT AERATION TANKS ...;..!.* 71
PROCESS AIR SUPPLY 76
AERATION TANK DISTRIBUTION 76
PLANT PERFORMANCE 75
vii
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FIGURES
Number
Page
1 General Plant Arrangement and Vicinity Plant
for Jones Island 3
2 Container & Separator Setting in Aeration
Tank for Jones Island ,. g
3 Framing Plan for an Aeration tank Batter
at Jones Island . 7
4 The Jones Island Wastewater Treatment Plant
in 1974 _ 30
5 Original Proposed Plant Expansion ........ 31
6 East Plant Aeration Tank Air Distribution
System as Originally Constructed . . 49
7 East Plant Aeration Tank Air Distribution
System--revision 50
8 General Plan of South Shore Wastewater
Treatment Plant 55
9 Schematic Diagram of the Diffuser Holder .......
Arrangement in the South Shore Aeration Basins ...... 57
10 Portion of the Diffuser Pattern in a South
Shore Aeration Basin 58
11 Air Supply System Schematic for Jones
Island East Plant 59
12 Flow Diagram Activated Sludge Process ........... 61
13 Existing Aeration Basin Flow Distribution
for-South Shore 62
14 General Site Plan for Jones Island Wastewater
Treatment Plant 72
15 The Jones Island Wastewater Treatment Plant
in 1974 73
16 Typical East Plant Aeration Basin ........ 77
vm
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TABLES
Number
Page
1 Record of Aeration Tank Cleaning From
1961-1983 17
2 West Plant Operating Data 22
3 Oxygen Inventory 1927-1982 . 25
4 West Plant Loading 1927-1981 . 27
5 East Plant Operating Data 40
6 Aeration Tank Cleaning of 5 Row Longitudinal
Pattern East Plant Tanks 1963-1981 45
7 East Plant Loading 1936-1981 . 52
8 South Shore Plan Annual Average Operating Data 64
9 South Shore Aeration Tank Cleaning Record
1981-1987 ...... 65
10 Data on Diffuser Plate Characteristics 85
11 Data on Weights of Diffuser Plates . 86
ix
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MILWAUKEE, WISCONSIN JONES ISLAND WEST PLANT AERATION, 1915.1982
INTRODUCTION
In 1914 the Sewerage Commission of the City of Milwaukee established a
testing station on Jones Island to determine the applicability of various
methods of sewage treatment to the treatment of Milwaukee sewage.
In 1915 the first continuous flow activated sludge plant was placed in
operation on Jones Island following initial work with a "fill and draw"
tank. Both of these experimental units contained 12" x 12" Filtros air
diffuser plates chosen after conducting tests comparing open air jets with
the porous plates. It is interesting to note that these original tanks
separated the plates with concrete dividers at 45 degree slopes.
Problems were encountered with the original Filtros plates due to
varying pore characteristics and strength, and in 1916, Mr. J. Edward
Porter of General Filtration Company Inc., the plate manufacturer, was
working closely .with Mr. William Copeland, Chief Chemist with the Commis-
sion, to improve plate quality.
m In attempts to obtain better oxygen transfer the North tank was
equipped with basswood plates in late 1916 and established in January, 1917
that fine bubble aeration would improve air economy (Nordell Report, April
19, 1917). Major problems developed with the basswood plates clogging and
after several months of work they were abandoned.
Additional work continued with General Filtration Company, - Inc. and
when the demonstration plant was constructed in 1918 using two'15 ft. deep
aeration tanks and two 10 ft. deep aeration tanks, they were equipped with
Filtros (aerating) plates type S guaranteed by the manufacturer to pass,
when dry, 10 cubic feet of air per minute under a pressure of two inches of
water" (from 5th Annual Report, page 41).
Due to the cost of cleaning the ambient air to prevent clogging of the
Filtros plates and the cost of Filtros plates, a test of grids of perfo-
rated black iron pipes as air diffusers was conducted. Sludge and rust
clogged the pipe and grid diffusers were abandoned (5th Annual Report,
pages 42-45).
The Filtros plates set in cast iron containers a-nd fed with black iron
pipe lines failed after a few months due to rust accumulated on the under
side of the plate (5th Annual Report, page 45). It was necessary to
provide galvanized pipe and concrete containers to resolve this problem.
On December 26, 1919, the Sewerage Commission unanimously and formally
adopted the activated sludge process as the one to be built by the city
The design of the 85 MGD West plant was developed from the data collected
from the testing station, the experimental plant, and demonstration plant
between 1914 and 1919.
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PLANT DESIGN
The 85 MGD Jones Island Plant approved by the Sewerage Commission in
1919 was unique since it incorporated the production of a commercial
organic fertilizer as the method of solids disposal.
To facilitate and maximize fertilizer production, fine screens were
chosen instead of conventional Imhoff tanks or primary settling basins.
These rotary screens with 3/32 by 2 inch openings removed material from the
grit chamber effluent which would cause problems in the aeration tanks and
the sludge handling processes. The substitution of fine screens for
primary sedimentation plus the large quantities of high strength industrial
waste from the meat packing, brewing and tanning industries provided strong
waste for treatment by the activated sludge process.
The design of the aeration tanks "and sedimentation tanks was described
by Mr. Darwin Townsend in Paper 1494, Transactions American Society of Civil
Engineers, vol. 85, pages 837-868 (1922) (Figure 1). Mr. Townsend was a design
engineer with the Commission who worked directly under Chief Engineer T.C.
Hatton from 1914 until 1921, when this paper was produced. The following
sections are taken directly from Mr. Townsend's paper:
The writer is entrusted with the development of designs
for the Milwaukee Sewerage Commission, and presents this
paper with the hope that it may contribute something to the
art of sewage disposal and help at some future time in the
solution of problems similar to those on which engineers
have been engaged in Milwaukee.
General Arrangement
The visualized conditions pertaining to the operation
of a large activated sludge disposal plant suggested an
arrangement of units similar to that of a large mechanical
water filtration plant wherein convenience of operation and
completeness of control are paramount.
The general idea followed in laying the foundation for
the design of the plant at Milwaukee was to secure an
arrangement which would provide operating galleries immedi-
ately adjacent to the rows of aeration and settling tanks
and place in them all the necessary appurtenances for the
complete control of the air, sewage, and sludge passing
through the plant.
Referring to Plate VI which shows the entire layout,
the plant will be seen to consist of twenty-four aeration
tanks and fifteen settling tanks - one row of aeration tanks
and one row of settling tanks on each side of the east and
west center line of the plant.
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HARBOR ENTRANCE
VArta un< Batten or C«.er.t«. «!«
M i CHI CAN
Figure 1. General Plant Arrangement and Vicinity Plan for Jones Island
Note: Plate No. VI in the paper, The Design of Aeration Units and
Sedimentation Tanks for the Activated Sludge Sewage Disposal Plant at
Milwaukee, Wisconsin, by Darwin Townsend, Trans. Amer. Soc. of Civil
.Engineers, vol. 85, pages 837-868 (1922). This paper was included as an
appendix in the Ninth Annual Report of the Milwaukee Metropolitan Sewerage
Commission for the year 1931.
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The sewage, after passing through the grit-chambers and
fine screens, and after receiving the proper quantity of
activated sludge at the outlet end of the fine screens, will
pass through the mixing channel between the fine screens and
the plant and will enter the main feed channel at the
extreme western end of the plant. At this point, the flow
will divide, half of it going through the two feed channels
which supply the aeration tanks north of the plant center
line, and the other half going to supply the aeration tanks
south of that line. Each aeration tank is separated into
two compartments by a baffle-wall, thereby causing; a
reversed flow. The flow enters the tanks through pipes' in
the end walls of the west compartments and leaves through
pipes equipped with meters at the end of the east compart-
ments. The outlet pipes pass through the two feed channels
which surround each of the settling tanks on three sides.
The settling tanks take their supply from the mixed
liquor channels through submerged gates in the east and west
walls of each tank, the effluent from each tank being
collected in troughs which discharge into each of the main
effluent channels running east and terminating at Lake
Michigan. The sludge is withdrawn from the bottom of each
settling tank and discharges into the two return sludge
conduits which convey it to the return sludge pumps in ,the
northeast corner of the main power house. From these pumps,
it is forced under pressure to the point of feed at the fine
screen outlet, as previously mentioned.
The plant is calculated to provide ample treatment
facilities for an estimated population of 588,750.
Aeration Units: Rate of Treatment
Results obtained from the operation of the demonstra-
tion plant at the testing station indicated the practi-
cability of operating the aeration tanks at rates as high as
20,000,000 gal. per acre per day without falling below the
adopted standards for the effluent. It was decided, how-
ever, to adopt 15,000,000 gal. per day as the conservative
rate on which to base the design.
The stated rate of 15,000,000 gal. per acre per day
applies to the quantity of sewage treated in each net acre
of horizontal, sewage surface in the aeration tanks only, the
settling tanks, channels, and walls not being included in
the computed area. When treating sewage at the rate of
15,000,000 gal. per acre per day, in a tank with a 15-ft.
depth of liquor and with 20% by volume of activated sludge
in the mixture, the corresponding period of detention
closely approximates 6 hours.
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In computing time of detention, displacement is assumed
not to occur in that part of the tank occupied by the
sludge. In other words, if a sludge content of 20% is
maintained in the sewage, the volume represented by this
percentage of sludge is assumed to occupy space in the tanks
permanently and is not available for detention purposes.
Each of the twenty-four aeration units is 236 ft. long,
44 ft. wide, and 15 ft. deep from the liquid surface to the
top of the diffuser plates, and based on a rate of
15,000,000 gal. per acre per day, with a sludge content of
20%, will treat approximately 3,580,500 gal. per day.
The volume of each tank is about 156,000 cu. ft. of
which 31,200 cu. ft. are reserved for the 20% of returned
sludge, leaving 124,800 cu. ft. of space available for the
detention of the sewage. The detention period corresponding
to 3,580,500 gal. per day passing through a tank the volume
of which is 124,800 cu. ft., will be, therefore, about 6
hours and 17 min.
Each aeration unit is designed for a reversed or
two-way flow, and the total length of travel is about 475
ft. The sewage which has been previously mixed with the
sludge in the feed channels, enters each tank through two
30-in., gate-controlled, inlet pipes in the end wall and
below the sewage surface and leaves the tank through a
24-in. outlet pipe equipped with a Venturi meter. The
outlet pipe discharges into the mixed liquor channels which
supply the settling tanks. The liquid level in the tanks is
maintained practically constant by an overflow weir 12 ft.
long, which forms one side of an outlet box connecting
directly with the outlet.pipe.
Figs. 1 and 2 show the general features of an aeration
unit. The ratio of square feet of diffuser area to square
feet of horizontal liquid surface is approximately 1 to 4.
Each of the cross-containers holds nine diffuser plates and
each of the containers running lengthwise through the
centers of the two compartments in each unit, holds seven
plates. The containers running lengthwise form a gutter in
each compartment, to be used for drainage purposes when
emptying a tank. Seven plates are used in each of these
containers for the purpose of facilitating the standard-
ization of the air-piping.
The supply of air to each unit enters at the end
adjacent to the side operating galleries, through a 12-in.
pipe, and is measured by an air meter. The 12-in. pipes
pass through the gallery walls, run downward, and branch
into two 10-in. pipes directly over the center of the 12-in.
partition walls in the center of the aeration units. The
10-in. air-lines are carried the entire length of each
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No. 1 Swrmioi- Block
No, < Separator Block '
, . ^_Sld. 5 f«te Conlainerf
[*---12-0->T^-7 Plan Containers
\*tt'o"4«-a'f^tV^I
PLAN
, . .
102 --- ~T --- lo::
T~T
. ,
»« . --- jo 1-
CROSS SECTION
/ i i , i , >""Con*ain£r
« 0k-4 0 * « «*'*"**'«
lrCW\
PARTIAL LONGITUDINAL SECTION
Figure 2. Container & Separator Setting in Aeration Tank for Jones Island
Note: Figure 1 in the paper, The Design of Aeration Units and Sedimentation
Tanks for the Activated Sludge Sewage Disposal Plant at Milwaukee, Wisconsin,
by Darwin Townsend, Trans. Amer. Soc. of Civil Engineers, vol. 85, pages 837-
868 (1922). This paper was included as an appendix in the Ninth Annual Report
of the Milwaukee Metropolitan Sewerage Commission for the year 1931.
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3.L, of Plant
Tanks North of C.L.«f
PJmnt are opposite band
Figure 3. Framing Plan for an Aeration Tank Batter at Jones
Island
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cpmpartment and are supported on top of the precast con-
tainer separator blocks. Each diffuser-plate container is
supplied with air through a 1 1/2-in. pipe connecting with
the 10-in. air-header.
Channels
The ratio of diffuser-plate area to the area of the
sewage surface in the feed and mixed liquor channels is
approximately the same as that in the aeration tanks, about
1 to 4, the return sludge channel being provided with a
ratio of about 1 to 6. .
The effective depth of all channels is 10 ft. This
depth permits the drainage system of the plant to be con-
structed under the channels, practically no additional
excavation being required. ;
The value of the aerated channels, as aeration units,
was considered at length, but owning to the variables, such
as quantities, velocities, length of travel, time of deten-
tion, etc., which entered into the problem, it was decided
finally to credit to the aeration plant as a safety factor
whatever benefits were derived from aeration in the chan-
nels.
The feed channels - two on each side of the plant at
the head of the rows of aeration tanks - are provided in
duplicate in order to insure against shutting off parts of
the plant should it become necessary to drain a channel for
the purpose of making repairs. All feed channels are
designed for the anticipated 1950 flow.
The mixed liquor channels are arranged so that sections
can be cut out of service and drained for the purpose of
making repairs, etc. Each section is comparatively small
and with only one section between two settling tanks out of
service, it is impossible to cut out of service more than
one entire tank. Owing to the probable infrequency of
having to make repairs in the mixed liquor channels, stop-
planks are to be used instead of sluice-gates. All the feed
channels and mixed liquor channels are 8 ft. wide.
The return sludge channels, each 6 ft. wide and 11 ft.
deep, are in duplicate for reasons already mention in
connection with feed channels. They receive the discharge
of sludge from the settling tanks and will contain a maximum
depth of 5.5 ft. of sludge, which will permit visual inspec-
tion of the sludge being discharged from each settling tank.
At the extreme west end of the plant, the two channels, each
of which are equipped with sluice-gates for control pur-
poses, unite into a small forebay at the head of a 54-in.
pressure conduit which carries the sludge to the return
sludge pumps.
8
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Air-Distribution System
The compressor plant for furnishing air will consist of
four, 30,000 cu. ft. per min., Ingersoll-Rand turbo blowers
direct connected to All is-Chalmers steam turbines. There
will be three active units and one spare.
No attempt will be made by the writer to give a de-
tailed description of the proposed compressor and power
plant. Only a few references will be made to the arrange-
ment, character, and capacity of the machinery. Each blower
will take its supply of air from the outside atmosphere
through screened louvers along the east side of the power
house and just below the roof.
The air will pass downward to the blowers through
36-in. cast-iron, inlet pipes equipped with Venturi meters
and spray washers for measuring and washing the volume of
free air to be compressed. After being compressed, the air
will be discharged through 30-in. cast-iron, outlet pipes
and enter the main air-header leading to the plant. The
capacity of each unit should be interpreted as meaning
30,000 cu, ft. of free air per min. compressed to 10 Ib. per
sq. in. '
The air requirements for the 1930 plant are based :on
supplying air to the aeration tanks at the rate of 1 1/2 cu.
ft. of air per gallon of sewage treated. The conversion of
the figure to a single diffuser-plate basis, assuming that
sewage is being treated at the rate of 15,000,000 gallons
per acre per day, with a diffuser ratio of 1 to 4, results
in a figure which indicates that each diffuser plate will
pass air at the rate of 1.48 cu. ft. per min.
Each aeration unit will actually contain 2,514 diffuser
plates, and if each plate is supplied with air at the rate
mentioned, the total air required per minute per aeration
unit will be about 3,820 cu. ft. and, for the twenty-four
units, about 90,680 cu. ft.
Air will be supplied for agitation to the diffuser
plates in all the aerated channels, at the approximate rate
of 1 cu. ft. of air per diffuser plate per minute. The
total number of plates in the channels is 11,520 and will
require about 11,520 cu. ft. of air per minute. The total
quantity of air required for the aeration tanks and channels
will be at the approximate rate of 103,200 cu. ft; per
minute. It will be noted that this quantity exceeds the
combined rated capacity of the three active blowers which is
90,000 cu. ft. per minute at a pressure of 10 Ibs.
-------
The secondary rating of the blowers, which is approx-
imately 35,000 cu. ft. of air per minute at a pressure of, 8
Ibs., indicates an available combined capacity of 105,000
cu. ft. per minute for the three units. This capacity is
more than ample to satisfy the air requirements for the
plant, and it is questionable whether the pressure losses in
the air-distribution system as a whole will ever exceed 8
Ibs. per sq. in.
Experience in operating the plant at the testing
station has shown conclusively that when foreign substances,
such as dirt and oil, are eliminated from the air supply,
there is little danger to be anticipated from the clogging
of diffuser plates and the resulting increase in pressure.
The equipment which has been selected and purchased for
compressing and washing the air, was designed and con-
structed under specifications which required a 100% perform-
ance relative to the quality of air delivered. The impor-
tance of a constant clean air supply is vital to the opera-
tion and maintenance of an activated sludge plant and should
not be under-estimated.
The problem of designing an adequate and practical
piping system for the distribution of air was given a great
deal of study and consideration and was finally developed
from the following basic conclusions.
First. - That the drop in pressure due to frictional
losses in the pipes should not exceed 1/2 lb., based on the
estimated requirements for the 1950 plant. This allowance
does not include the fixed loss through the check-valve and
gate-valve on each blower outlet pipe and the loss through
the diffuser plates.
Second. - That accurate and convenient facilities
should be provided for measuring the volume of air supplied
to each aeration unit and to the mixed liquor, feed, and
return-sludge channels.
Third. - That the pressure drop in the aeration units
should be based on the quantity of air required to treat
sewage at the rate of 20,000,000 gallons per acre per day,
allowing 1 1/2 cu. ft. of air per gallon of sewage, of 1.98
cu. ft. of air per diffuser plate per minute.
General Arrangement of Air-Piping. - One of the first
steps in the design was to give separate consideration to
the depths of liquor in the aeration units and in 'the
channels. The depth of liquor in the aeration units, as
noted previously, is 15 ft.; that in the feed and mixed
liquor channels is 10 ft.; and that in the return-sludge
channels is about 5 1/2 ft. maximum.
10
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The largest proportion of the total quantity of air is
used in the aeration units. It is here, also, that the
maximum pressure is required, owing to the depth of the
liquor.
It was decided, therefore, after having compared the
cost of providing and operating separate low-pressure
blowers for supplying air to the channels with the cost of
supplying air at an excessive pressure from the large units,
that better economy could be obtained through the use of a
system of sub-headers carrying pressure suitable to the
depth of liquor, the supply of air being taken from the main
air-headers and the reduction in pressure obtained through
resistance in pressure-reducing valves.
The two sub-headers which supply the feed and mixed
liquor channels with air are connected to the two main
air-headers at points about opposite the center of the
middle units of the 1950 plant, the connection pipes, which
are 12 in. in diameter, being equipped with pressure-
reducing valves and air meters.
The sub-header supply air to the return sludge channels
and the mixing channel is connected to the main air-header
at the western end of the, plant, in the gate-house. This
connection which is 8 in. in diameter is also equipped with
a pressure-reducing valve and an air meter.
Each aeration unit will take its supply of air directly
from the main airheader, the connection being made at the
top of the header in order to avoid carrying condensate into
the piping of the aeration unit.
The connecting pipes between the main air-headers and
the piping in the aeration units are 12 in. in diameter, and
each pipe is equipped with a gate-valve and an air meter.
The assumption has been made that increasing the size
of the air pipes will increase the cost of the installation
at a rate of theoretically proportional to each 1 oz.
increment of reduced pressure drop. This assumption,
however, is not correct, because of the fact that, in
enlarging the air pipes to reduce friction losses, only
those sizes which show comparatively large losses would be
increased substantially, and those which show lesser compar-
ative losses would be increased in lesser proportion.
Character of Pipe Required. - Precautions against the
formation of rust which eventually may clog the diffuser
plates, on the inside walls of pipes carrying air, is quite
important in the design of an air pipe system for the
activated sludge process and should not be overlooked. The
tendency for the pipe to rust is due principally to the
presence of moisture in the compressed air, a condition
which appears is impossible to prevent.
11
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The presence of moisture in the air is due to condi-
tions of the atmosphere and also to the action of the water
sprays on the air while it is passing through the air-
washers.
No doubt, moisture will be present in the air mains in
the form of condensate, resulting from differences in
temperature between the compressed air, which will leave the
blowers at probably 140 degrees F., and the outside atmos-
phere. This condition indicates the necessity for providing
traps and blow-offs for removing condensate from the system.
Cast-iron pipe, Class A bell and spigot, was adopted
for the main air-headers and for the headers in the aeration
units. It was selected on account of its lasting qualities,
rigidity, resistance to corrosion, and the ability of the
lead joints to allow movement due to expansion and con-
traction.
Rigidity is referred to as an important factor with
special reference to the larger sizes - from 36 to 66 in.-as
compared with equal sizes of made-up commercial pipe of less
substantial construction. All cast-iron pipe is to be well
coated inside and out, with asphaltum paint.
All the sub-air headers and the small piping in the
channels and aeration units are to be of galvanized wrought-
iron pipe. All the fittings are likewise to be galvanized.
Diffuser Plates. - The diffuser plates to be used are
hard and porous and will not disintegrate or show signs of
deterioration when they are immersed in sewage and subjected
to the chemical actions taking place therein.
The specifications under which the filtros plates are
being manufactured for the Sewage Commission of Milwaukee
provide that each plate, when dry, shall pass air at the
rate of from 8.9 to 12.9 cu. ft. per min. under a 2-in.
water pressure. The plates are to be placed in precast
concrete containers. The setting of the containers and
making the air-pipe connections thereto will not be done
until the construction of the aeration units and channels is
practically completed.
The present filtros-plate containers and the container
separators are being manufactured at the rate of about 60
pieces per day, by the Sewerage Commission, in its own
casting plant which was constructed especially for this
purpose. The plant is completely equipped with the neces-
sary steel forms, cranes, tram-cars,.mixing plant, and steam
room.
12
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The manufacture of the containers and separators,
particularly the containers, is work requiring extreme care,
and the product being turned out of the plant is first-class
in every respect.
Conclusion
The work has been directed and developed under the
direction of T. Chalkley Hatton, M. Am. Soc. C.E., Chief
Engineer of the Sewerage Commission, and for several years
past Harrison P. Eddy, M. Am. Soc. C.E., has been employed
by the Commission in the capacity of Consulting Engineer.
Those of the Sewerage Commission staff, beside the
writer, who have been associated intimately with the devel-
opment of the process from its inception, and also with the
more recent work of preparing final designs, are James L.
Ferebee, M. Am. Soc. C.E., Principal Assistant Engineer;
William R. Cope!and, Affiliate, Am. Soc. C.E., Chief
Chemist; A. Lawrie Kurtz, Assoc. M. Am. Soc. C.E. Division
Engineer and Designer; Henry M. Heisig, Assistant Chief
Chemist; Anthony J. Magerl, Architectural Engineer; H.
Erskine Nicol, Assoc. M. Am. Soc. C.E. Senior Engineer; and
M. Bert Langeler, Structural Engineer and Designer.
AERATION PLANT START-UP EXPERIENCE 1925-1930
The Plant was placed in operation on June 26,' 1925. During the
initial winter season (1925) the water washed air filtration system failed
to operate due to freezing. This caused the plant to shut down and the
water washed air filters were abandoned (12th Annual Report, page 29-30).
Four type U-2 Midwest air filters with a capacity of 35,000 CFM were
installed. Each unit contained 42 cells of baffle impingers made of
expanded metal treated with "Viscosine". They were "guaranteed under
normal conditions to offer not more than .375 inches of water pressure
resistance - not to increase moisture in the air - to remove 98% of dust
and soot and 95% of oil" (Nov. 22, 1928 letter to Vern Wenicke, Testing
Engineer).
Review of the operational files of the Commission show continuing
problems with winter operation of filters due to freezing (Dec. 20, 1929
Report). The freezing problems and subsequent collapse of filters probably
contributed to some of the problems with clogging of plates in the aeration
tanks.
In 1930 four Midwest Filter Company "Airmat Filters" were purchased
and installed in series with the four existing Baffle Impingement Viscosine
treated units to improve the air quality and reduce plate underside clog-
ging.
13
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The Filtros plates in aeration tanks 1,3, and 5 failed in 1927 and were
replaced with Norton plates "that have a greater capacity, ranging from 11 to 16
cubic feet of air per minute". The original Filtros plates installed in these
three tanks had "the lowest capacity when tested under a pressure of 2 inches of
water column" (1927 Annual Report, page 23).
In 1930 the plates in aeration tanks 1, 3, 5, and 7 were replaced.
Norton plates were installed in tanks 1 and 3 and Filtros plates in tanks 5
and 7. The plates installed in 1930 were individually tested by a Commis-
sion test engineer at the manufacturers plants in East Rochester, New York,
and Worcester, Massachusetts. Only plates that passed 15.5 to 20.5 cubic
feet of air per minute were accepted. Each plate was rated and marked and
uniformly installed later in the four aeration tanks.
AERATION TANK FOULING PROBLEMS AND PLATE CHANGES
For some unknown reason the major aeration tank fouling originally
occurred in the twelve north tanks (odd nos. 1-23). This was documented in
reviewing old plant records. A January 25, 1930 report stated
... the north side of plant seems to have a greater pressure
difference than the south side, the pressure difference on
the north side will average around 5.75 ft. as compared to
5.50 ft. on the south side. We seem to have more trouble
with the plates in aeration tanks on the north side than we
do with those on the south side.
Several of the tanks on, the north side of the plant have
been taken out quite a number of times due to the fact that
tank was not taking the required amount of air. This
characteristic is probably caused by the plates being
plugged up, and the pressure is not sufficient to obtain the
required flow of air thru the plates. When these tanks are
removed for cleaning, considerable grit is found deposited
at the bottom of the tank laying on the plates, after this
is removed and the plates are scrubbed, the required air
flow is maintained for a short time and then it starts
falling off again. The mix liquor head on the north side is
slightly less than that on-the south side, this difference
also would cause a small increase in the pressure
difference.
Major changes in the north side tanks are presented below in chronological
order as follows:
1. Original 1.5 inch thick Filtros plates in tanks 1,
3, and 5 changed to Norton Alundum Plates 1 inch
thick permeabilities 11-16 in 1927.
2. Norton Alundum plates in tanks 1 and 3 changed to 1
inch thick Norton Alundum plates with permeabilities
15.5 to 20.5 in 1930.
14
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3. Norton Alundum plates In tank 5 and original Filtros
plates in tank 7 changed to 1 1/2 inch thick Filtros
plates permeabilities 16-30 in 1930.
4. Original Filtros plates in tanks 9, 11, 13, 15, 17, and
19 changed to 1 1/2 inch thick Filtros plates permea-
bilities 18-21 in 1931.
5. Norton plates in tanks 1 and 3 replaced with 1.5 inch
thick Filtros plates permeabilities 18-19.5 in 1953.
6. Original 1 1/2 inch thick Filtros plates in tanks 21
and 23 replaced with 1 inch thick Filtros plates with
permeabilities 39-41 in 1961.
In contrast the twelve aeration tanks in the south half of the plant
(even nos. 2-24) contain the original 1 1/2 inch thick Filtros plates with
permeabilities of 9-10 which were .installed in 1923 and 1924. The only
modification that occurred was a reduction in the number of plates from
2514 to 2348 per tank when the tanks were altered in 1933 to provide the
East Plant feed channels.
The only other major change in the aeration tanks was a replacement of
the original 1 1/2 inch galvanized wrought iron piping between the 10 inch
cast iron air headers and the plate holders. This piping was replaced with
.PVC piping in 1963 to eliminate rust buildup in the entrance to the plate
holder.
PVC small diameter piping in aeration tanks was first used in the East
Plant in 1954. .
AERATION TANK CLEANING
Accurate aeration tank cleaning records are unavailable prior to 1961.
From review of the Commission Annual reports it was noted that the south
side tanks were not cleaned between 1933 and 1946, since the construction
of the East Plant feed channels eliminated cleaning equipment access to the
area. The following is taken from the 1946 Annual Report:
In May plans and specifications were approved and
proposals received for installing a concrete cover other the
north feed channel serving the plant extension to be used as
a roadway for servicing and cleaning the twelve south
aeration tanks of the West Plant. The bids ranged from
$20,246.00 to $20,817.00, which were considered too high and
on recommendation of the Chief Engineer and General Manager
the bids were rejected and the project abandoned.
15
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The twelve aeration tanks in the south half of the West
Plant having been in continuous operation for some ten
years, they were taken out of service beginning in June,
1946 and were cleaned by day labor furnished by the Stdne
Construction Co. on basis of cost of labor, insurance,
materials, rental of equipment, plus 15% profit. Where
necessary, diffuser plates and air piping were renewed by
employees of the Commission.
The equipment used to clean these tanks was placed on
planking, and the sludge deposit in the bottom was sluiced
to the end of the tank and then pumped up to a pipe header
at the top which carried it to a spoil bed. The diffuser
plates which are permanently installed with grout were then
sand blasted on the surface, washed, and the tank put back
in service.
This cleaning was necessitated due to the plate resis-
tance to passage of air having increased to such an extent
it was not possible to get effective purification. After
cleaning, the tanks were brought back to approximately 95%
of normal"operating conditions.
The work was completed in September, 1946 at a cost of
$14,411.18.
After cleaning the south aeration tanks in the West
Plant, and while the men and equipment were available,, it
was determined to inspect the north side tanks which had
been cleaned in 1942. Two of these tanks were taken out of
service and cleaned at a cost of $2,817.50, but their
condition did not warrant the cleaning of others.
In March of 1953 Contract 576 was let to provide "a concrete roadway
over the North half of the feed channel leading to the East Plant". This
provided equipment access to allow cleaning of the south side tanks (from
1953 Annual Report, page 24).
This leads to the conclusion that the south side tanks were again not
cleaned between 1946 and 1953. :
Review of tank cleaning records for the period from 1961 (the last
major plate replacement tanks 21 and 23 north side) through 1983 are
summarized on Table 1. No tanks have been cleaned more than five times in
the 22 year period, and the average number of tank cleanings was 3.3 in the
22 year period, or an average of every seven years. Cleaning consisted of
hand removal of accumulated solids and water washing the tank using fire
hoses. When additional plate treatment was deemed necessary, the plates
were sandblasted in place. When a tank was taken put for cleaning it was
scheduled in advance and done as quickly as possible. Air pressure was
maintained on the plates at all times during the period they were out of
service. Table 1 indicates that sandblasting was done on a very infrequent
basis during this period.
16
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Tank Number
1 & 3
5 & 7
9 & 11
13 & 15
17 & 19
*21 & 23
TABLE 1
Record of Aeration Tank Cleaning From 1961-1983
North Tanks
Year Cleaned
1962, 69, 73, 80, 83
1962, 67, 80
1962, 79
1961, 67, 80
1961, 67
1967, 77, 79, 80, 81
Year Sandblasted
1967
1962
1961, 67
1961
1967, 77
Other
**Brushed and
Acid Washed 1981
South Tanks
Tank Number
2 & 4
6 & 8
10 & 12
14 & 16
18 & 20
22 & 24
Year Cleaned
1963, 67
1963, 67, 81
1963, 67, 80
1963, 67, 79
1963, 78, 81, 83
1963, 67, 79, 80, 83
Year Sandblasted
1963
1967
1967
1963
1963, 67
1963
Other
*New plates installed in 1961 - 1-inch thick Filtros Plates, permeability 39-41,
17
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AIR SUPPLIED TO AERATION SYSTEM
When the first portion of the East Plant was constructed in 1932-34,
-additional steam turbine driven air compressors were added to the power
house. Two 50,000 CFM blowers were provided under contract #356 and ad-
ditional airmat filters under contract #360. Contract #360 also provided
for remodeling the air intake chambers to allow the use of air from the
power house during the coldest periods of the year.
When the addition to the East Plant was proposed, plans to add two
115,000 CFM air compressors (2-115,000 CFM) were included (1947 Annual
Report, page 10-12). These additional units were not approved and the
45 M.G.D. addition completed in 1951 had to be supplied by the existing
blowers.
In 1967 Black & Veach Consulting Engineers were engaged to make a
complete study of the current and projected power needs of the entire
plant. Based on these studies made it was decided to continue power pro-
duction at the plant utilizing two 16 MW gas turbines to provide electrical
power for new process air compressors, to replace the steam turbine driven
blowers. ' . .
Gas turbine electric power generation was selected since the turbine
exhaust heat could be utilized to furnish 70% of the heat required in the
sludge drying process.
A new compressor building containing air filtration equipment and four
compressors each capable of producing 110,000 CFM at 10 psig was put in
service in December, 1973. The compressors are powered by 5500 HP 4,160 V
synchronous motors. The electric power required is provided by the gas
turbine generators with backup by the electric utility thereby guaranteeing
100% reliability.
The new filters consisted of four (4) Rollo-Matic air filters (mats)
followed by four (4) electrostatic agglomerators followed by bag filters.
Intermittent cold weather operational problems developed with frost buildup
on the Rollo-Matic filters. This appeared to be related to the fact that
the air intake was located adjacent to the North aeration tanks. An
alternate air intake was completed in 1978, and this solved the frost
problem.
MILWAUKEE EXPERIENCE WITH POROUS PLATE DIFFUSERS 1913-1982
The engineers and scientists involved in the design and operation of
the Milwaukee Jones Island Wastewater Treatment Plants were deeply involved
from 1915 in attempting to install the best aeration plates in both the
East and West Plants.
As noted in the Introduction, the first recorded work with a plate
manufacturer occurred in 1916. Prior to the construction of the first
section of the East Plant, extensive studies on plates manufactured by the
three United States producers of plates, the Filtros Inc., the Norton
18
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Company and the Carborundum Company, were conducted by the Commission's
Engineering Department and the results shared with the manufacturers.
Based on these tests both Carborundum and Norton plates were initially
installed in the first twelve aeration tanks in the East Plant. These
plates had permeability ratings of 32 to 36 in contrast to Norton plates
installed earlier in the West Plant tanks (1, 3, and 5 in 1927 and 1 and 3
in 1930) which had permeability in the 11 to 16 and 15.5 to 20.5 ranges.
In 1951 following provision of Filtros plates with permeabilities in
the 19.5 to 24 range for seven of the new East Plant aeration tanks,
Mr. H.M. Heisig who had been with the Commission since 1915, reviewed the
Commission's plate experiences and pointed out the superior performance of
the Filtros product (Report to R.D. Leary, August 9, 1951). Mr. Heisig
also indicated that more plates were needed in the East Plant and suggested
installation of higher permeability Filtros plates in one tank for test
purposes (Filtros plates with permeabilities from 36-44 were installed in
East Plant aeration tank 20).
In 1956 the Commission again tested plates in this instance using a
glass-windowed tank with plates under water. Tests were run on Aloxite
plates produced by Carborundum Company, Kellundite and Electro Flow plates
produced by Electro Refractories and Alloy Corporation of Buffalo, New
York, silica and new Filtros organic bond plate produced by the Filtros
Corporation and the Alundum plate produced by the Norton Company.
Extensive tests were made on all plates with permeabilities varying
from 10 to 34.5 CFM. Tests were conducted under 10 to 15 feet of water
with the main testing done under 13 feet of water and with air rates of 1
to 3 cubic feet per minute, 9.5 to 12 cubic feet per minute, 14 to 20 CFM
and 25 - 35 CFM (all plates were 1 square foot plates). Observations were
made of the plate surfaces and areas above the plates at the various air
f1ows.
Start up characteristics were determined after the plates were left
without air but under the 13 foot water head.
The majority of the work was designed to determine plate performance
in terms of pressure drop at air flows from 1 to 3 c.f.m. and to determine
uniformity of the air patterns leaving the plate at different air rates.
In 1960 18,000 silica plates with permeabilities ranging from 33.3 to
40.7 and thickness of 1 inch were purchased from Filtros for replacement
purposes and to rep!ate West Plant tanks 21 and 23.
Based upon all testing and operations and maintenance experience,
Filtros silica plates were selected as most satisfactory and the Commission
experience is summarized as follows in the 1964 Annual Report, pages .35-36:
19
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Sewerage Commission of December 14, 1964
the City of Milwaukee
Gentlemen:
In order to complete the remodeling of the East Plant
aeration system from a circulatory to a modified ridge and
furrow system, it will be necessary to purchase 35,000
Filtros plates.
Thirty-five years experience in operating the aeration
systems with various types and kinds of plates has resulted
in a recommendation by our plant operating personnel that a
Filtros diffuser plate is the only plate, currently manufac-
tured, that meets our operation and maintenance require-
ments.
The Filtros silica diffuser plate was a patented
article originally patented in the process of manufacture
relating to porous mineral products of a general nature in
patent No. 1,117,601 dated November 17, 1914 and patent No.
1,118,441 dated November 24, 1914 which patents were
assigned to Filtros, Inc. and later succeeded by patent No.
2,008,327. These patents are now expired and neither the
process of manufacture of the plates nor the plates them-
selves are currently covered by an outstanding patent.
However, Filtros, Inc. is the sole manufacturer of a silica
diffuser plate as there is no other known manufacturer of a
silica plate.
Our operating, staff has determined that the diffuser
plates shall have a permeability rating of from 15 to 21
with a mean of 18. The plates shall be 1 1/2" thick,
manufactured of round grain silica sand and the thickness
shall not be less than 1 1/2" to allow for restoring perme-
ability by sandblasting or surface spelling.
To complete the project of remodeling the East Plant
aeration system in 1965, it will be necessary to purchase
35,000 plates for delivery beginning in April, 1965.
Funds have been provided in the 1965 Capital Budget for
this work.
In that Filtros, Inc. of East Rochester, New York is
the sole and exclusive manufacturer of bonded silica dif-
fuser plates, 1 1/2" thick and 12 inches square, a proposal
was obtained from said company for furnishing and delivering
35,000 Filtros silica diffuser plates as specified by the
Sewerage Commission .for a unit price of $3.39 per plate or a
total cost of $118,650.00.
20
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In that the silica diffuser plate is manufactured
solely by Filtros, Inc. of East Rochester, New York and in
that the best interests of the Sewerage Commission would be
served, I recommend that I be authorized to purchase 35,000
Filtros diffuser plates according to specifications of the
Sewerage Commission for the sum of not to exceed $118,650.00
in accordance with proposal submitted by Filtros, Inc. under
date of October 30, 1964.
Respectfully submitted,
Ray D. Leary
Chief Engineer & Gen. Mgr.
The Commission approved the purchase of approximately
35,000 Filtros diffuser plates for the sum of not to exceed
$118,650.00 on the recommendation of the Chief Engineer &
Gen. Mgr.
When the secondary treatment facilities were being designed for the
120 MGD South Shore facility in 1971, the Commission staff again insisted
on 1 1/2 inch thick Filtros plates (permeability 15 to 21) in the aeration
tanks.
WEST PLANT PERFORMANCE 1927-1981
The Jones Isla-nd West Plant in addition to treating a strong waste-
water provides the gravity thickened waste sludge to the sludge drying
operations. The waste sludge production is maintained by dedicating
specific aeration tanks and clarifiers exclusively for the production of
waste sludge. The number of aeration tanks involved in the sludge disposal
function varied from two to six (8 to 25% of capacity) during the 54-year
period with the number increasing as more wastewater was treated at the
Jones Island Plant. The aeration tanks dedicated -to sludge disposal are
usually fed mixed liquor at a constant rate to provide the most stable
waste sludge for chemical treatment. This function tends to reduce the
plant capability to process the maximum amount of wastewater and should be
recognized when evaluating plant capability. Plant operational data is
available through 1987, however, in 1982 a program of truck transportation
of South Shore lagooned anaerobically digested sludge and raw waste acti-
vated sludge was initiated. These South Shore sludges were added to the
coarse screened sewage (lagoon sludges) and to the West Plant mixed liquor
(v/aste activated sludges). This additional load, particularly'on the West
Plant where some north aeration tanks were converted to sludge holding
tanks, altered the waste loading and the plant loading data cannot be
considered typical.
The plant data is shown on the attached Table 2 and is based upon
annual averages (arithmetic mean) of daily 24-hour composite samples. The
early plant effluent data is skewed to the low side due to the practice of
not sampling spewing clarifiers (prior to 1965).
21
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TABLE 2
West Plant Operating Data
Annual Averages
Year
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952 .
1953
1954
1955
1956
1957
1958
1959
1960
1961
Flow
(MGD)
54.98
81.84
85.08
77.17
79.39
78.98
82.59
78.73
85.61
78.48
75.43
76.88
76.26
76.18
73.65
71.41
71.33
68.84
65.40
66.41
79.23
79.04
75.11
77.47
75.45
72.28
67.65
72.67
68.59
65.22
71.55
73.68
80.73
86.24
78.26
Screen
Sewage
BOD (PPM)
239.2
271.4
256.6
277.9
275.3
268.8
250.9
289.6
. 197.7
176.9
166.0
160.2
179.7
256.0
277.1
309.4
302.1
335.6
332.3
366.0
336.0
334.0
316.1
304.8
300.7
295.5
282.6
270.8
281.3
290.0
323.8
316.8
276.2
252.6
276.8
Effluent
BOD (PPM)
9.13
11.80
8.80
9.40
14.90
14.60
12.50
16.10
8.60
9.30
8.80
6.80
8.80
12.90
17.70
23.90
20.60
19.20
18.30
17.70
30.10
18.10
15.90
13.60
16.60
16.80
13.80
15.60
11.60
10.80
14.60
18.10
16.30
19.00
23.50
Aeration
Tanks in
Service
19.1
20.1
22.8
22.7
23.3
23.5
23.9
24.0
24.0
23.5
23.8
24.0
24.0
24.0
24.0
23.5
24.0
23.5
24.0
23.4
24.0
. 24.0
24.0
24.0
23.4
23.0
21.8
22.8
23.0
24.0
22.6
23.9
23.8
23.9
23.0
Air/gal
Sewage
2.09
1.35
1.38
1.54
1.61
1.63
1.56
1.61
1.45
1.50
1.57
1.53
1.53
1.57
1.63
1.77
1.74
1.80
1.90
1.92 - ,
1.68
1.69
1.86
1.64
1.78
1.47
1.46
1.40
1.42
1.58
1.46
1.46
1.36
1,29
1.41
Aeration Tank
Loading _
#800/1000 ftj
41.64
66.82
57.90
57.13
56.72
54.63
52.43
57'. 45
42.65
35.73
31.82
31.03
34.53
49.14
51.42
56.85
54.30
59.45
54.76
62.81
67.08
66.52
59.82
59.50
58.63
56.16
53.03
52.19
50.73
47.66
61.99
59.06
56.65
55.12
56.95
22
-------
TABLE 2 - continued
Year
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
Flow
(MGD)
76.91
73.01
80.98
82.70
77.40
74.50
76.30
76.40
77.70
76.80
70.90
68.10
62.10
53.00
53.90
47.70
52.50
54.00
48.00
50.00
Screen
Sewage
BOD (PPM)
291.4
317.4
307.2
293.0
293.0
297.0
306.0
239.0
208.0
220.0
218.0
261.0
302.0
347.0
326.0
329.0
313.0
290.0
291.0
273.0
Effluent
BOD (PPM)
17.80
20.20
18.30
17.10
14.30
15.10
26.80
21.30
12.40
20.00
16.00
18.00
15.00
31.00
22.00
15.00
15.00
15.00
13.90
11.30
Aeration
Tanks in
Service
23.3
22.9
24.0
24.0
24.0
' 23.98
23.3
23.9
23.2
24.0
24.0
24.0
24.0
22.0
22.0
22.0
22.0
20.0
21.0
20.0
Air/gal
Sewage
1.35
i.45
1.35
1.26
1.36
1.40
1.37
1.36
1.37
1.44
1.62
1.67
2.06
2.37
2.77
2.75
2.43
2.33
2.66
2.50
Aeration Tank
Loading
#800/1000 ft6
58.17
61.19
62.68
61.05
58.00
58.10
59.40
47.80
41.50
43.10
39.30
44.80
47.10
51.50
48.40
43.30
44.80
46.50
40.90'
41.80
23
-------
The use of fine screens for primary treatment in addition to the heavy load
of organic material from the area industries contributes to the high
(Biochemical Oxygen Demand) BOD found in the screened sewage applied to the
aeration system.
The annual variation in BOD (160.2 - 366.0 mg/L) and flow (48.00 to
86.24 MGD) is related primarily to economic conditions and the changing
service area over the 54-year period.
The air used per gallon of sewage treated is shown along with the
aeration tank loading in terms of pounds of BOD per 1000 cubic feet of
aeration tank.
It should'be noted that the aeration tank loadings from 1927 through
1964 were calculated from data contained in the Annual Reports. Data
listed since 1965 is the arithmetic mean of daily aeration tank loadings.
The large increase in air use per gallons of sewage noted after 1974
reflects the addition of the modern process air facility at that time. The
oxygen transfer capability of the plant as judged by the aeration tank
loadings has remained high throughout the'54-year period particularly when
one takes into consideration the increasing percentage of aeration tanks
dedicated to sludge disposal as the East Plant sludge contribution increas-
ed due to plant additions and increased loading.
Table 3 relates the pounds of oxygen applied to the mixed liquor via
the.air supplied to the pounds of BOD removed. This attempt to relate
pounds of oxygen applied to pounds of BOD removed on an annual basis did
not show significant trends due to the other variables involved such as
changing BOD of the screened sewage, the quantity of air available (depen-
dent upon installed blower capacity), and the volume of sewage treated.
Table 4 summarizes the BOD and suspended solids loadings to the West
Plant for the 54-year period. It is interesting to note the decline in
plant loading which occurred in the late 1970's.
24
-------
TABLE 3
Oxygen Inventory 1927-1982
Year
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
Total
Sewage
Flow
(MGD)
YR AVG
54.98
81.84
85.08
77.17
79.39
78.98
82.59
78.73
85.61
78.48
75.43
76.88
76.26
76.18
78.65
71.41
71.33
68.84
. 65.40
66.41
79.23
79.04
75.11
77.47
75.45
72.28
67.65
72.67
68.59
65.22
# 0,
Addid
(Thousand
#)
2151
2069
2198
2225
2393
2410
2412
2373
2324
2204
2218
2202
2184
2239
2248
2366
2324
2320
2326
2387
2492
2501
2616
2379
2514
1989
1849
1905
1824
1929
# BOD
Removed
(Thousand
il
105
177
176
173
172
167
' 164
180
135
no
99
98
109
154
159
170
167
182
171
193
202
208
188
188
179
168
152
155
154
152
# 09
Added
I~B15U
Removed
20.39
11.67
12.50
12.88
13.88
14.39
14.69
13.21
17.21
20.09
22.4.2
22.39
20.10
14.50
14.11
13.92
13.88
12.77
13.58
12.38
12.33
12.01
13.91
12.64
14.07
11.13
10.34
12.32
11.82
12.70
Of -
Reduction
96.4
95.5
96.6
96.7
94.3
93.9
94.9
94.0
95.4
94.3
94.2
95.2
94.8
94.6
93.6
91.9
93.1
94.3
94.4
95.1
92.8
94.5
95.0
95.2
94.2
94.0
95.0
93.0
95.6
96.1
Sewage
'BOD
(PPM)
239.2
271.4
256.6
277.9
275.3
268.8
250.9
289.6
197.7
176.9
166.0
160,
179,
256,
277.1
309.4
302.1
335.6
332.3
366.0
336.0
334.0
316.1
304.8
300.7
295.5
282.6
270.8
281.3
290.0
25
-------
TABLE 3 - continued
Year
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
MAX
MIN
AV6
STD
Total
Sewage
Flow
(MGD)
YR AVG
71.55
73.68
80.73
86.24
78.26
76.91
73.01
80.98
82.70
77.40
74;50
76.30
76.40
77.70
76.80
79.90
68.10
62.81
53.00
53.60
48.20
53.30
53.60
48.00
50.17
51.92
86.24
48.00
71.77
10.16
# 0,
Added
(Thousand
ii
1956
2014
2056
2083
2066
1944
1982
2047
1951
1971
1953
1957
1945.
1993
2071
2150
2129
1851 '
2352
2780
2982
2425
2338
2390
2344
2255
2982
1824
2206
238.3
# BOD
Removed
(Thousand
11-
185
184
175
168
165
175
181
195
190
180
175
178
139
127
128
119
138
149
140
136
126
132
132
111
109
109
208
98
156
28.7
# 0,
Add&d
F~BUD~
Removed
10.60
10.97
11.75
12.40
12.50
11.08
10.95 ,
10.49
10.25
10.96
11.15
11.00
14.02
15.72
16.12
18.66
15.43
15.45
16.84
20.46
14.66
18.31
17.67
21.56
21.43
20.61
22.42
10.25
14.65
3.57
%
Reduction
95.3
94.0
93.7
91.9
91.0
93.4
93.4
93.6
93.8
94.9
94.7
91.4
90.0
93.5
90.6
91.9
92.8
95.0
91.1
93.3
95.4
95.2
94.9
95.2
96.7
90.0
Sewage
BOO
(PPM)
323.8
316.8
276.2
252.6
276.8
291.4
317.4
307.2
293.0
293.0
297.0
306.3
239.0
208.0
220.0
218.0
261.0
302.0
347.0
326.0
329.0
313.0
312.0
291.0
366.0
160.2
26
-------
TABLE 4
West Plant Loading 1927-81
Year
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
Flow (MGD)
54.98
81.84
85.08
77.17
79.39
78.98
82.59
78.73
85.61
78.48
75.43
76.88
76.26
76.18
73.65
71.41
71.33
68.84
65.40
66.41
79.23
79.04
75.11
77.47
75.45
72.28
67.65
72.67
68.59
65.22
71.55
73.68
80.73
86.24
78.26
S c
(PPM)
239.2
271.4
256.6
277.9
275.3
268.8
250.9
289.6
197.7
176.9
166.0
160.2
179.7
256.0
277.1
309.4
302.1
335.6
332.3
366.0
336.0
334.0
316.1
304.8
300.7
295.5
282.6
270.8
281.3
290.0
323.8
316.8
276.2
252.6
276.8
r e e n e d
BOD . .
(10-* x Ib)
109,681
185,243
182,075
178,856
182,280
177,057
172,820
190,154
141,155
115,785
104,428
102,717
114,291
162,647
170,206
184,266
179,717
192,677
181,248
202,713
222,022
220,171
198,011
196,931
189,216
178,132
159,443
164,123
160,915
157,741
193,220
194,671
185,962
181,680
180,664
S e
wage
Suspended SoUds
(PPM)
283.0
326.0
320.0
338.0
272.0
264.0
269.0
264.0
242.0
261.0
278.0
256.0
271.0
290.0
302.0
299.0
295.0
310.0
315.0
317.0
297.0
304.0
333.0
309.0
290.0
289.0
299.0
288.0
280.0
284.0
271.0
263.0
266.0
265.0
265.0
(10" x Ib)
129,765
222,510
227,062
217,536
180,095
173,895
185,287
173,345
172,785
170,831
174,886
164,142
172,358
184,249
697,926
771,538
743,257
. 867,660
872,985
967,624
832,265
846,810
877,879
785,488
727,273
174,214
168,696
174,548
160,171
154,478
161,713
161,611
179,095
190,599
172,962
27
-------
TABLE 4 - continued
Year
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
Flow (MGD)
76.91
73.01
80.98
82.70
77.40
74.50
76.30
76.40
77.70
76.80
70.90
68.10
62.10
53.00
53.90
47.70
52.50
54.00
48.00
50.00
Scree
BOD
(PPM) (10
n e d
3
S e
wag
291.4
317.4
307.2
293.0
293.0
297.0
306.0
239.0
208.0
220.0
218.0
261.0
302.0
347.0
326.0
329.0
313.0
290.0
291.0
273.0
185,163
193,266
207,475
202,087
189,136
184,535
194,721
152,285
134,788
140,913
128,905
148,236
156,410
153,381
146,546
130,882
137,047
130,604
116,493
113,841
(PPM)
273.0
306.0
294.0
307.0
301.0
304.0
314.0
227.0
206.0
197.0
220.0
292.0
264.0
283.0
312.0
342.0
352.0
326.8
298.8
244.3
(10" x Tb)
175,110
186,324
198,560
211,743
194,300
188,884
199,811
144,639
133,492
126,181
130,087
165,843
136,729
125,092
140,252
136,054
154,123
147,178
119,616
101,873
28
-------
MILWAUKEE, WISCONSIN JONES ISLAND
EAST PLANT OR EXTENSION AERATION HISTORY, 1930-1981
INTRODUCTION
By 1930 the Jones Island West Plant had exceeded its capacity and
the Commission Engineers began developing plans for the plant extension.
The extension, designed to treat the projected sewage flows to the year
1945, was located east of the existing West Plant on property purchased
from the City of Milwaukee Harbor Commission (Figure 4). A total of 28
acres of land was acquired, "17.74 acres of which were submerged land in
Lake Michigan directly east of the sewage treatment plant the remainder
10.46 acres being filled land lying directly south thereof",(1931 Annual
Report, page 6 and 7).
One of the conditions the Commission accepted in purchasing the
property provided for an easement for a roadway east of the existing
West Plant thereby preventing the Engineers from implementing the
expansion plans for additional aeration tanks and sedimentation tanks
developed earlier (See Figure.5).
The mayor of the City of Milwaukee opposed expansion of the sewage
treatment facility and in 1931 the Common Council of the City of
Milwaukee engaged Harrison P. Eddy to advise them on "the necessity of
enlarging the sewage treatment plant at this time". Mr. Eddy, on
January 13, 1931, referred to his previous work in 1921 and stated "a
review of the conditions affecting the water supply supports and con-
firms the conclusions reached in 1921 and I am now of the opinion that
the city should provide forthwith a water filtration plant" (1931 Annual
Report, page 32).
He further pointed out that volume of sewage not treated in 1929
was 13.62 MGD and in 1930 it was 18.59 M6D.
Mr. Eddy's conclusions were:
As a result of my knowledge of local conditions
and the capabilities of the sewage treatment plant, I
have reached the following conclusions briefly stated.
If the Commission should proceed forthwith in the
preparation of plans and the construction of the
proposed enlargement of the plant as recommended
herein, such enlargement would not be ready for treat-
ing additional sewage flows until 1935. By 1935 it is
estimated that the population of the Metropolitan
Sewerage District will have increased to 790,000 or
201,000 in excess of the design capacity of the treat-
ment plant. The estimated sewage flow for 1935 is 125
M.6.D. or 39 M.G.D. in excess of the design capability
of the treatment plant.
29
-------
3-OX 0
-------
Figure 5. Original proposed plant expansion
31 ;
-------
The discharge of such large quantities of untreat-
ed sewage to the rivers, already loaded beyond their
safe diluting capacity, will result in seriously
objectionable conditions. Moreover, some of the
improvement which has been secured in the quality of
the raw and chlorinated water supply and in the quality
of bathing beach waters and in the rivers will be
gradually reduced until additional sewage treatment
facilities shall have been provided.
When considering the expenditure of $5,000,000 for
enlarging the treatment plant, an obligation of about
$7,500,000 including interest charges, it should be
viewed in the light of the obligation already incurred
of about $50,000,000. Until such time as treatment can
be provided for all of the sewage collected, much of
the value of the sewerage system and existing treatment
plant will not be utilized. ;
In my judgment, it would be unwise to depend upon
the harbor inside the breakwaters for purification of
the dry weather flow of sewage by natural agencies.
The unavoidable excess of storm flows discharged,
surface runoff and plant effluent must of necessity
pass into the harbor and this polluting matter is all
the burden that should be placed upon these waters. If
the harbor were to be utilized as a receiving basin for
untreated dry weather flow of sewage, great quantities
of polluting matters would accumulate there and pollute
bathing beach waters and be a potential source of
serious contamination of the water supply.
During the years 1929 and 1930 the sewage treat-
ment plant has reduced the polluting matters in the
sewage treated by about 96% and it has removed from the
total sewage flow of the Metropolitan District about
77% of such material.
Sewage treatment has produced a substantial
improvement in the quality of the raw water supply and
has possibly caused a similar improvement in the
chlorinated water.
The additional dryers will increase the capacity
of the existing plant on the average of about 10 M.G.D.
Filtration of the water is necessary for its
purification and the city should provide forthwith a
water filtration plant.
It is necessary to enlarge the sewage treatment
plant for the protection of the water supply and of the
water of the harbor and bathing beaches and for the
completion of the work of cleaning up the rivers.
32
-------
The enlargement of the sewage treatment plant
should take precedence over the building of a water
filtration plant if it is necessary that either im-
provement shall await the completion of the other.
Enlargement of the sewage treatment plant should
not be postponed pending further study of new processes
or radical modifications in the existing process. :
Purification of the sewage without the treatment
and disposal of the sludge is not possible.
The fertilizer plant is not run at a profit, but
the income from the sale of fertilizer pays a large
proportion of the cost of treating and disposing of the
sludge.
Respectfully presented,
(Signed) HARRISON P. EDDY
The Common Council of the City of Milwaukee approved the aforementioned
sale of 28 acres on May 4, 1931, and ultimately passed it over Mayor Hoan's
veto on June 1, 1931, allowing the Commission to proceed with construction of
the 70 MGD plant extension.
PLANT EXTENSION
The following is a description of the additional facilities provid- !
ed as described in the 1934 Annual Report:
Following is a resume of the Plant Extension and the
relation of the various units to the present plant:
Plant Extension
When the Activated Sludge process of sewage
purification was tentatively adopted by the Sewerage
Commission in August, 1917, (formally adopted in
December, 1919) it was determined that because of it
being a new system of sewage disposal, developed at
Milwaukee, and never having been in practical use in
any other city in the world, it was advisable to build
the aeration and .sedimentation tanks with a capacity
for the 1930 period only, or for an average daily flow :
of 85 million gallons of sewage.
It was further determined that when that period
was reached additional tanks could be added to the east
of the present tanks and any improvements in design or
construction developed through the years of operation
could be incorporated in the new work.
The coarse screens, grit chambers and fine screens
were designed for a daily capacity of about 320 million
gallons each and needed no increase in capacity.
33
-------
The original plant, as built, has a mixing chamber
located a short distance beyond the fine screens where
return sludge is added to the raw sewage. Following
the mixing chamber are the "north" and "south" gal-
leries and the "center" gallery. The north and south
galleries are over the feed channels which carry the
mixed liquor to the relative aeration tanks. In these
galleries also are the air mains carrying the air to
the aeration tanks. The center gallery is'over the
return sludge channel which carries the return sludge
back to the pumps from where it is pumped to the mixing
chamber. (It now also houses the new air main leading
from the Power House to the plant extension.)
In the original plant are 24 aeration tanks, each
236 feet long, 44 feet wide inside, with a baffle wall
extending lengthwise through the center of the tank to
within 12 feet of the far end which provides for a
2-way or return flow. These tanks have an effective
depth of 15 feet, and in the bottom of each, at right
angles to the direction of flow are placed diffuser
plates on the "ridge and furrow" principal which gives
a diffuser ratio of one to four. The diffuser plates
have a permeability rating of 18 to 24 cu. ft. of :air
per minute.
There are 15 sedimentation tanks, octagonal at the
top and circular at the bottom, and 15 feet deep,
equipped with clarifying mechanisms. Eleven of these
tanks are 98 feet in diameter from which the settled
sludge is returned to the raw sewage, and four are 42
ft. 6 in. in diameter from which the settled sludge
passes through a gravity line to the acid house, thence
it is pumped to the filters, carried to the dryers and
disposed of by selling as a fertilizer.
The plant extension was designed for an additional
average daily flow of 70 million gallons of sewage,
which is the expected additional amount to be received
in 1945.
To provide sufficient space for the plant exten-
sion it was necessary to reclaim from the lake an area
approximately 700 feet by 1000 feet, having a depth, of
from 12 to 18 feet of water, and adjacent to the
present plant. This was done by the building of steel
sheet bulkheads and a concrete dock wall on wood pile
foundation, which were completed in February, 1933, at
a cost of $652,695.69. This area was then dewatered
and there were driven 705,000 lineal feet of wood piles
as a foundation to support the proposed aeration and
sedimentation tanks and galleries. This foundation,
together with the necessary ground leveling, was
completed in November, 1933, at a cost of $187,606.07.
34
-------
The original north and south feed channels were
designed with a view of extending them to carry the
mixed liquor to the plant extension, and the center
gallery was designed to carry the return sludge from
the plant extension to the return sludge pumps, but
because of the hydraulic gradient and frictional losses
to overcome it was deemed advisable to construct new
channels for those purposes and separate from the
original channels.
IN DESIGNING THE PLANT EXTENSION THE "CIRCULATORY"
FLOW WAS INCORPORATED, AS PRACTICED WITH GOOD RESULTS
AT CHICAGO AND INDIANAPOLIS, RATHER THAN THE "RIDGE AND
FURROW" PRINCIPLE USED IN THE ORIGINAL PLANT.
The circulatory flow is brought about by placing
the diffuser plates along one side only in the bottom
of the channels and aeration tanks instead of at right
angles to the flow of the liquor. This will result in
a saving in the number of diffuser plates, containers
and separators used, and their maintenance.
The new mixed liquor channel was designed as a box
section 13 feet 3 inches deep and 12 feet wide, built
of reinforced concrete, and is connected with the
original sewage channel at a point just beyond the fine
screen house. It has a single 'row of diffuser plates
in the bottom along one side of it to keep the liquor
well agitated to prevent settlement of solids. It runs
southerly a distance of about 90 feet to the control
gate house where return sludge will be added to the raw
sewage going to the plant extension. From the gate
house this box section is divided by a center wall into
two channels, with open top, and extends eastwardly
between the south aeration tanks and the sludge storage
building to the plant extension, a distance of over a
thousand feet. To make room for this and the sludge
storage building it was necessary to cut 13 feet off
the ends of the aeration tanks. A single row of
diffuser plates are placed in the bottom of each
channel along the dividing wall, and when the air is
forced up through these plates an upward and circu-
latory flow is created which will sweep the bottom
clean and prevent deposits of solids.
The new return sludge channel was designed as a
box section 13 feet wide, 14 feet 6 inches deep, with a
dividing wall in the center 7 feet, 9 inches high,
making two independent channels. A row of diffuser
plates is placed in the bottom along one side of each
channel through which air will be forced to keep the
sludge well agitated and prevent settlement. This
channel runs west from the plant extension along the
35
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north side of the north aeration tanks to the return
sludge pumps from where it will be pumped into the raw
sewage entering the new mixed liquor feed channels.
The mixed liquor feed channel, return sludge
channel and the control gate house were completed in
May, 1933, at a total cost of $152,596.05.
There are 12 new aeration tanks, each one being
370 feet long, 44 feet wide, and 16 feet, 7 inches
deep, with a dividing wall in the center having a 10
foot opening in the far end which will provide for a
2-way or return flow. In the bottom of each tank,
along one side, will be a double row of diffuser plates
(side by side) through which air will be forced to
aerate the mixed liquor and create a circulatory flow.
The top of the walls of these tanks are a curved Tip
extending partially over the top of the tanks to aid in
the circulatory flow. Each of these tanks will have a
daily capacity of 5.75 million gallons with a detention
period of 6 hours.
There are 6 new sedimentation tanks built of
reinforced concrete 84 feet wide, 161 feet 6 inches
long and 14 feet deep, equipped with duplicated revolv-
ing sludge removal mechanisms. Each tank is capable of
settling the solids from 21,705,600 gallons of mixed
liquor in 24 hours at a maximum unit sedimentation rate
of 1600 gallons per square foot of horizontal liquid
surface.
The aeration and sedimentation tanks were com-
pleted in October, 1934, at a cost of $767,371.08.
The twelve "Tow-Brow" sludge removal mechanisms,
with steel truss supports, are a 2-arm aluminum pipe
header with throat pipe openings for removing the
sludge from the bottom of the six new sedimentation
tanks and were furnished at a cost of $71,340.00.
There were 27,000 diffuser plates purchased for
the diffusion of air in the plant extension at a cost
of $1.13 3/4 each. Half of the quantity of these
plates were obtained from the Carborundum Company, and
half from the Norton Company. They are 12 inches
square and 1 inch thick, having a permeability rating
of from 32 to 36 cu. ft. of air per minute. There are
1296 plates in each aeration tank, placed in two rows
in the bottom, along one side - the rows being 18
inches apart.
36
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In connection with the installation of the dif-
fuser plates the following contracts were entered into:
Manufacture of concrete containers and
and separators $37,738.20
Setting containers and separator
blocks. 18,345.00
Setting diffuser plates in
containers . 11,762.40
The containers are made of reinforced concrete,
rectangular box shape, with a recess at the top on
which the diffuser plates are set with cement grout.
The standard container holds 9 plates, and installed in
one end is a pipe elbow to which the air feed pipe is
attached, permitting the air to enter under the plates
and pass up through them.
The main air header carrying the air at 10 pounds
pressure from the turbo blowers in the power house to
the plant extension is a 2-ply stainless steel clad
pipe, 60 inches in diameter and 1/4 inch thick, with
welded joints, and was furnished and installed at a
cost of $107,000.00. The air headers in the aeration
tanks and channels, being immersed in the sewage, are
cast iron pipes with lead joints.
The additional equipment required to supply
compressed air to the plant extension consists of two
steam driven turbo blowers - one bleeder type and one
straight condensing type - made by Allis Chalmers Mfg.
Co., each capable of compressing 50,000 cu. ft. of free
air per minute to ten pounds pressure. These turbo
blowers, with foundations, were installed at a cost of
$214,023.00.
The increase in steam requirements was obtained by
changing the type of stokers serving the four water
tube boilers, at a cost of $57,632.00.
In addition to the above units the following major
items were also contracted for:
37
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Sluice gates and appurtenances $ 24,591.93
Pipe gallery building 22,212.00
Operating gallery buildings 101,334.00
Miscl. structural steel, railings
and gratings 54,430.00
Air meters, Effluent meters and
Sewage Flow Meters 32,575.00
Pulling steel piling and
furnishing top soil 20,356.00
Cutting off piling, grading, etc. 11,946.00
Wire fence south boundary of
property 2,064.00
Removing stone from old bulkhead 2,200.00
Air piping in aeration tanks,
channels, galleries, etc. 115,214.00
Electric Wiring and appurtenances 13,950.00
Air filters and remodel air
intake chambers 20,761.00
$421,633.93
The plant extension when completed will represent
a total expenditure of approximately $3,000,000.00.
The plant was placed in service on December 3, 1935, eliminating
the discharge of 30 million gallons of untreated sewage per day (1935
Annual Report, page 4).
The initial operations of the extension indicated that good results
were obtained with the "circulating flow" type of aeration.
The results of operation of the plant extension,
in which the aeration tanks were designed on the
"circulatory flow," as compared with the original
plant, in which the aeration tanks were designed on the
ridge and furrow" type, are almost identical. (1936
Annual Report, page 20)
The original plant has been is operation since
June, 1925, and is operated on the "ridge and furrow"
type of aeration. The plant extension has been in
operation since December, 1935, and is operated on the
"circulatory flow" type of aeration. The results
obtained in the purification of the sewage by the
operation of the two units correspond very closely-
38
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Original Plant
Plant Extension
Bacteriological reduction 97.8% 98.0%
Suspended solids removal 93.3% 94.5%
B.O.D. reduction 94.2% 95.7%
Total air used per gallons of
sewage treated-tanks and
channels 1.5 c.f. 1.70 c.f.
(1937 Annual Report, Page 15)
Review of the plant operating records indicate that the extension was
operated far below its 70 MGD design capacity (1936- 38.65 MGD, 1937-
40.84 MGD) during these years. It was further noted that a major decrease
in BOD concentration occurred when entire volume of available sewage was
accepted for treatment (see Table 5 attached).
By 1941 loading was increasing and purification in the East Plant was
declining, and in 1942 and 1943 an additional row of plates was added to
the twelve aeration tanks increasing the number from 1296 per tank to 1944
per tank.
The Metropolitan area continued to grow and in 1947 the Chief Engineer
recommended that the plant extension be increased in capacity from 70 MGD
to 115 MGD. In 1948 the Commission approved purchase of the first material
needed for the proposed expansion.
When the expansion proposal was made in 1947, two steam turbine driven
blowers each with capacities of 115,000 CFM were included. These units
were not approved by the Commission, leaving the plant with a total blower
capacity of 220,000 CFM.
The expansion completed and placed in service in December, 1951, added
eight aeration tanks and four sedimentation basins. The new spiral flow
aeration tanks were constructed with four rows of Filtros plates to improve
aeration tank performance.
Based upon experience with plates of different manufacturers, the
Commission specified Filtros plates for this new addition (permeabilities
19.5 to 24) with one experimental tank installation with Filtros plates
with permeabilities of 36 to 44 (Heisig Report, August 9, 1951!).
In March, 1951, the Commission retained the consulting engineering
firm of Alvord, Burdick & Howson to evaluate the sewage disposal plant and
sewer system. ,
In their 1956 report, Alvord, Burdick & Howson recommended that East
Plant return sludge lines be separated and the plant provided with its own
return sludge handling facilities.
39
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TABLE 5
East Plant Operating Data
Annual Averages
Screen Aeration Aeration Tank
Flow Sewage Effluent " Tanks in Air/gal Loading ,
Year (M6D) BOD (PPM) BOD (PPM) Service Sewage #600/1000 ft6
1936 38.65 176.9 7.8 12.0 1.54 20.89
1937 40.84 166.0 6.6 12.0 1.70 20.71
1938 44.99 160.2 6.7 11.9 1.35 22.20
1939 45.10 179.7 8.0 12.0 1.17 24.76
1940 44.09 256.0 . 13.3 12.0 1.18 34.48
1941 51.17 277.1 18.1 12.0 1.01 43.32
1942 56.32 309.4 21.7 12.0 1.14 53.23
1943 56.53 302.1 17.4 12.0 1,12 :52.17
1944 54.15 335.6 17.3 12.0 1.36 55.52
1945 56.02 332.3 17.0 12.0 1.26 56.87
1946 55.56 366.0 16.2 12.0 1.32 62.12
1947 59.16 336.0 31.7 12.0 1.23 60.73
1948 58.38 334.0 15.4 12.0 1.33 59.57
1949 56.99 316.1 14.3 12.0 1.43 55.03
1950 57.19 304.8 12.0 12.0 1.65 53.25
1951 65.21 300.7 ' 17.6 12.3 1.43 58.36
1952 91.08 295.5 15.5 20.0 1.33 49.33
1953 86.78 282.6 14.9 17.0 1.26 52*88
1954 89.54 270-.8 15.7 17.0 1.15 ; 52.29
1955 96.88 281.3 15.2 19.0 1.17 52.58
1956 90.53 290.0 13.3 20.0 1.28 48.12
1957 87.04 323.8 17.3 19.2 1.35 53.81
1958 83.22 316.8 19.6 18.5 1.40 52.24
1959 94.34 276.2 20.5 18.6 1.32 51.36
1960 101.13 252.6 30.7 18.4 1.22 50.90
1961 96.46 276.8 43.9 18.8 1.35 52.06
1962 95.30 291.4 40.6 19.5 1.38 52.21
1963 88.86 317.4 59.8 19.5 1.54 53.02
1964 89.69 307.2 29.0 19.7 1.43 51.27
1965 103.40 293.0 12.0 19.6 1.22 56.67
1966 108.90 293.0 15.4 19.7 1.20 60.30
1967 109.0 297.0 18.2 20.0 1.22 60.20
1968 107.2 306.0 19.2 - 20.0 1.21 60.50
1969 105.2 239.0 14.8 19.5 1.20 47.50
1970 94.2 208.0 16.5 19.2 1.27 38.30
40
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TABLE 5- continued
Year
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
Row
(MGD)
100.0
96.0
92.2
85.4
78.0
81.6
78.0
79.8
79.0
73.0
74.0
68.0
80.0
73.5
81.7
85.4
Screen
Sewage
BOD (PPM)
220.0
218.0
261.0
302.0
347.0
326.0
329.0
313.0
290.0
291.0
273.0
263.0
304.0
291.0
278.0
254.0
Effluent
BOD (PPM)
19.0
18.0
17.0
18.0
22.0
21.0
18.0
21.0
20.0
14.8
14.9
15.8
14.7
13.4
12.8
9.3
Aeration
Tanks in
Service
20.0
20.0
19.0
19.0
16.0
16.0
16.0
17.0
17.0
16.0
15.0
13.0
15.0
13.0
15.0
14.0
Air/gal
Sewage
1.28
1.36
1.36
1.53
1.57 .
1.51
1.55
1.46
1.57
1.58
1.51
1.60
1.36
1.51'
1.49
1.26
Aeration Tank
Loading -
#600/1000 ftj
41.0
39.30
46.0
50.90
60.40
60.40
58.0
55.80
51.90
48.0
.47.30
' 50.0
65.10
62.40
58.80
58.0
41
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The District's technical staff involved in plant operation (Plant
Superintendent, Laboratory Director, and Division Engineer-Plant Design)
concurred in the recommendation and the East Plant return and waste sludge
facility was completed and placed in service on July 29, 1958.
During the same period (1954-1958) changes to improve the efficiency
of the East Plant aeration were being made. Additional aeration plates
were added to tanks and in 1956 a tank of experimental diffuser tubes was
installed.
In 1957 a program to convert the entire twenty aeration tank plant to
spiral flow tapered aeration using ceramic tubes was undertaken. The
conversion to ceramic tubes was justified since it would "increase the
volume of air per gallon of sewage and reduce the back pressure on the air
headers" (1959 Annual Report, page 26).
As the aeration tanks were converted from spiral flow with plate
diffusers to spiral flow tapered aeration with tube diffusers, the plant
performance deteriorated. The annual average BOD of the plant increased
from 19.6 mg/liter in 1958, to 30.7 mg/liter in 1960, to 59.8 mg/liter in
1963 (BOD Annual Average see Table 5).
A plant scale research project started in 1961 ultimately led to
conversion of all twenty aeration tanks to a five row longitudinal diffuser
placement pattern utilizing nine plate containers with a total of ten plate
containers or ninety diffuser plates on each down header. A total of 3,150
plates were installed in each of the aeration tanks. The tanks remained
doublepass with each pass 22 ft. wide by 370 ft. long. The ratio of
theoretical tank surface to plate surface was 5.17 compared to the 4 to 1
design provided in the original ridge and furrow design of the!West Plant.
To reduce conversion costs and to complete the conversion as soon as
possible, most of the old plate containers from the original spiral flow
plate tanks were steam cleaned and reinstalled in the aeration tanks. It
was impossible to distinguish between the original Carborundum and Norton
plates installed in 1934 in tanks 1-12. These plates were grouped together
and installed in tanks 9, 10, and 11. The additional new plates installed
were all 1 1/2" Filtros fused silica plates with permeabilities ranging
from 15 to 21. One tank of 1 inch thick Filtros resin bonded plates with
permeabilities 17 to 19 was installed for experimental purposes since data
on the new type plate was desired.
The details of the East Plant conversion from spiral flow plates to
spiral flow tubes to the ultimate 5 row longitudinal diffuser pattern with
the 3,150 plates per aeration tank is described in detail in two papers
published in the Journal of Water Pollution Control Federation, ("Effect of
Oxygen-Transfer Capabilities on Wastewater Treatment Plant Performance",
July 1968, pages 1298-1310, and "Full Scale Oxygen Transfer Studies of
Seven Diffuser Systems", March 1969, pages 459-473).
42
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These papers also document the deterioration in effluent quality and
the plant operating problems which occurred in the East Plant due to the
inability to transfer sufficient oxygen to the mixed liquor in the tube
diffuser equipped spiral flow aeration tanks.
The separation of the East Plant return .sludge with the East Plant
waste sludge added to the West Plant return sludge caused serious operating
problems in the West Plant. The complete plant separation of the secondary
treatment plants which occurred on August 14, 1961 when the East Plant
waste sludge was removed from the West Plant and diverted directly to the
fertilizer waste stream resulted in improved capacity and effluent quality
in the West Plant (see July, 1968 paper).
The ultimate conversion of the twenty East Plant aeration tanks to the
five row longitudinal pattern was completed in 1966 and the East Plant
waste sludge was again returned to the West Plant return sludge to improve
the sludge wasting operation.
During the transition period 1957-1966 every, effort was made to
proportion the plant loadings between the East and West Plants to obtain
the best possible total plant effluent. This resulted in higher aeration
tank loadings in the West Plant and lower loadings in the East Plant during
the early part of the period.
In view of the long-standing disagreements between District profes-
sional personnel on the provision of the spiral or circulatory flow in the
East Plant aeration tanks and the operating problems that must be attri-
buted to their installation, it is most interesting to read in retrospect
the comments of the three individuals most involved when return sludge
separation was proposed i.n 1956.
Quotation from Mr. H.M. Heisig Laboratory Director in charge of
Process Control in the plants.
EAST PLANT RETURN SLUDGE HANDLING.
Obviously this Report proposes to separate the East and
West Plants.
This Report proposes to construct a return sludge
pumping station near settling tank number ten in the
East Plant, thereby eliminating certain undesirable
features present in the existing setup and resulting in
savings as well as improvement in operation, etc. I am
most heartily in accord with this plan since it was my
feeling from the outset that separation of return
sludge was necessary in order to evaluate the new plant
which, at the.time, some felt would successfully treat
sewage with a substantial saving in air. It was never
possible to make comparison between operation of the
East and West Plants since they are interconnected.
43
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Quotation from Mr. Wm. Landsiedel Plant Superintendent and former
Design Engineer in charge of Plant Operation and Maintenance.
Page 14: East Plant Return Sludge Handling
A return sludge pumping plant for the East Plant
was considered when the Plant was designed in 1930.
One reason among others for not building such a plant
was that the operating labor cost would have been much
higher than the cost of air used in the mixed liquor
and return sludge channels.
If this pumping plant were to be built, there is
an indicated maximum saving in the cost of air in the
amount of $25,000.00 which must be balanced against the
additional operating labor cost of approximately
$20,000.00. The pumping cost will be slightly higher
because of additional equipment needed to bring the
waste sludge to the West Plant.
It, therefore, appears that there will be no
savings in operating cost; the only benefit will then
be, according to the Report, the quality of the return
sludge.
In disposing of the waste sludge, which according
to the proportion of both Plants is approximately 60%
of the total volume, it ought to be considered to
deliver this sludge to the waste sludge facilities in
the West Plant and not to the east end of the West
Plant return slu.dge channels, in order to keep the
sludges from both Plants separated.
Quotation from Mr. Joseph A. Maiers, Division Engineer in charge of
Plant Design.
East Plant Return Sludge Handling
In full agreement with proposed plan. Somewhat higher
operational cost with the proposed plan, but purifi-
cation efficiency and capacity should be considerably
increased.
AERATION TANK CLEANING
As pointed out earlier, the plates installed in the final five row
longitudinal patterns during the years 1963-1966 consisted ;of used and
new plates and plate containers. Table 6 summarizes the tank cleaning
records from 1966 through 1981 and breaks the aeration tanks into -four
categories based on plate type and past history. The tank cleaning
history was terminated in 1981 since a major revision of the East Plant
aeration tanks was initiated in 1982 as part of the Jones Island Plant
rehabilitation program.
44
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TABLE 6
Aeration Tank Cleaning of 5 Row Longitudinal
Pattern East Plant Tanks 1963-1981
Tanks with New Filtros Plates
Tank #
1
5
13
14
15
16
17
18
19
20
Reused
Tank #
3
4
6
7
8
9
Year
Modified
1966
1966
'1965
1965
1965
1965
1965
1965 ,
1965
1965
Filtros Plates
Year
Modified
1963
1963
1966
1964
1966
1964
Year Cleaned
1969, 73, 77, 81
1969, 74
1966, 74, 77, 78
1966, 73, 80
1966, 67, 73
1966, 67, 73, 77, 78,
1980, 81
1966, 67, 73
1966, 67, 73, 79, 80
1966, 67, 73
1966, 67, 73, 81
Year Cleaned
1969, 73, 74, 76, 77
1978, 80, 81
1969, 74, 81
1966, 73, 81
1972, 73
1974
1966, 70, 74
Year Acid Year Sand
Washed Blasted
1981 1977
1978 .
, 1973'
; 1967
1980, 81 1967
1967
1967
1981 ; 1967
Year Acid Year Sand
Washed Blasted
1980, 81 1973, 76, 78
1981
1981 1966
1972
: 1970
45
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TABLE 6 - continued
Reused Carborundum and Norton
Year
Tank # Modified
Year Cleaned
Year Acid
Washed
Year Sand
Blasted
10
11.
12
1964
1964
1964
1966, 70, 73, 79, 80, 1970, 80
1966, 67, 69, 74, 80, 1981
1981
1966, 67, 72, 74, 75, 1981
1980, 81
1970
1974
Filtros Resin Bonded
Tank #
Year
Modified
Year Cleaned
Year Acid
Washed
Year Sand
Blasted
1965
1969, 73
1969
46
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In April 1973, the East Plant aeration tanks were inundated by a huge
storm on Lake Michigan. The high lake level and the strong northeast winds
deposited large quantities of debris in the aeration tanks making a com-
plete cleaning of all tanks necessary. All aeration tanks were cleaned in
1973 and 1974 to remove storm debris which varied from 23 to 180 cubic
yards per tank (mainly sand and gravel).
The cleaning records are difficult to analyze since no reason for
cleaning is included and when one reviews Table 5, which lists aeration
tanks in service, it is evident that in 1974 a decrease in aeration tank
use occurred. This allowed the operating personnel to discontinue the use
of poorly operating tanks such as 10, 11, and 12, which contained the
oldest and least efficient plates.
The sixteen aeration tanks containing Fi.ltros silica plates were
cleaned every four (4) years on the average. Examination of Table 2,
however, shows an unexplainably wide variation in cleaning ranging from
once in sixteen years to eight times during the same period. For example,
adjacent aeration tanks 15, 16, and 17 had new Filtros plates installed in
1965 and were placed in service in May and June. All three were cleaned
after the first year and after the second year of service and; tanks 15 and
16 were sandblasted on the discharge end in 1967. All three were again
cleaned in 1973 to remove storm debris. Four additional cleanings and two
acid washings were performed on tank 16 between 1973 and 1981 while the
tanks on both the north (17) and south (15) were in continuous service with
no cleaning. All tanks receive mixed liquor from a common channel and air
from a common air header.
The big increase in tank cleaning which occurred in 1980 and 1981
reflects the acceptance of acid cleaning by the plant management.
AIR SUPPLIED TO AERATION SYSTEM
When the first portion of the Plant was constructed in 1932-34,
additional steam turbine driven air compressors were added to the power
house. Two 50,000 CFM blowers were provided under contract #356 and ad-
ditional airmat filters under contract #360. Contract #360 also provided
for remodeling the air intake chambers to allow the use of air from the
power house during the coldest periods,of the year.
When .the addition was proposed, plans to add two 115,000 CFM air
compressors (2-115,000 CFM) were included. These additional units were not
approved and the 45 MGD addition completed in 1951 had to be supplied by
the existing blowers.
In 1967 Black & Veatch Consulting Engineers were engaged to make a
complete study of the current and projected power needs of the Jones Island
Plant. Based on these studies, it was decided to continue power production
at the"plant utilizing two 16 MW gas turbines to provide electrical power
for new process air 'compressors to replace the steam turbine driven
blowers.
47
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Gas turbine electric power generation was selected since the turbine
exhaust heat could be utilized to furnish 70% of the heat required in the
sludge drying process.
A new compressor building containing air filtration equipment and four
compressors each capable of producing 110,000 CFM at 10 psig was put in
service in December, 1973. The compressors are powered by 5500 HP 4,160 V
synchronous motors. The electric power required is provided by the gas
turbine generators with backup by the electric utility, thereby guaran-
teeing 100% reliability.
The new filters consisted of four (4) Rollo-Matic air filters (mats)
followed by four (4) electrostatic agglomerators followed by bag filters.
Intermittent cold weather operational problems developed with frost buildup
on the Rollo-Matic filters. This appeared to be related to the fact that
the air intake was located adjacent to the North aeration tanks. An
alternate air intake was completed in 1978, and this solved the frost
problem.
CHANGES IN AIR DISTRIBUTION
Initially all air subheaders were submerged in the aeration tanks.
The original plant (12 aeration tanks) used 'Cast iron subheaders with the
single header supplying air to the plates on both passes. The 1951 addi-
tion (8 aeration tanks) utilized 20 inch steel subheaders in the same
manner.
Due to corrosion of the headers (particularly the steel units) and
primarily to improve air distribution, the headers were removed from
aeration tanks 1 and 6 and placed on the walkway between tank passes in
1955. Valves were installed on the new stainless steel downheaders to
better control air distribution in each section of the aeration tank. The
piping from the stainless steel downheaders to the individual nine plate
containers was changed to plastic to resolve the corrosion problems (1955
Annual Report, page 47, 48, and 49). See Figures 6 and 7.
When the tube diffusers were installed (1956-1960) all air subheaders
were placed on the walkways and stainless steel downheaders provided.
The stainless steel downheaders and plastic piping to the nine plate
containers with individual air control on each downheader were incorporated
into the five row longitudinal design. A total of ninety plates were
serviced by each of the downheaders.
EAST PLANT PERFORMANCE 1936-1981
l
The East Plant operating data is shown on Table 5 and is based upon
annual averages (arithmetic mean) of daily 24-hour composite samples. The
early plant effluent data is skewed to the low side due to the practice of
not sampling spewing clarifiers (prior to 1965).
48
-------
01
at
I
*
.O
4?
.Q
'C
*^
OT
XJ
O
c Us
Ol-r;
E o
-------
distribution
50
-------
The use of fine screens for primary treatment in addition' to the heavy
load of organic material from the area industries contributes to the high
(Biochemical Oxygen Demand) BOD found in the screened sewage applied to the
aeration system.
The annual variation in BOD (160.2 - 366.0 mg/L) is related primarily
to economic conditions and the changing service area over the 45-year
period.
The air used per gallon of sewage treated is shown along with the
aeration tank loading in terms of pounds of BOD per 1000 cubic feet of
aeration tank. '
It should be noted that the aeration tank loadings from 1936 through
1964 were calculated from data contained in the Annual Reports. Data
listed since 1965 is the arithmetic mean of daily aeration tank loadings.
Plant design capacity was initially 70 M.6.D. and was increased to 115
M.G.D. when the addition was completed in 1951.
The low plant loadings in the early years were due to a low BOD in the
wastewater and an operating decision to load the West Plant more heavily.
The plant effluent data in Table 5 between 1935 and 1963 shows the
effect of the higher aeration tank loadings with the less efficient spiral
flow or circulatory aeration system. The ultimate collapse of the system
occurred when the plant return sludges were separated in 1958 and plate
diffusers were replaced by tube diffusers in an attempt to reduce back
pressure and increase air addition.
The plant recovery upon the conversion to the five row longitudinal
diffuser pattern is shown in Table 5 with an increase in aeration tank
loading and decline in effluent BOD concentration (1963-1966). Continuous
recording of aeration tank effluent dissolved oxygen on selected aeration
tanks was initiated in 1966 and this data used to reduce air consumption.
Table 7 summaries the BOD and suspended solids loadings to the East
Plant for the 45-year period. It is interesting to note the decline in
plant loading which occurred in the late 1970's. This decline in plant
loadings lead to the reduction of aeration tank capacity utilized (see
Table 5 "Aeration Tanks in Service"). ;
Air use increased in 1974 with the addition of the new process air
compressors.
The East Plant 1930 design, incorporating the circulatory or spiral
flow concept of aeration, obviously led to serious operating problems
before it was finally replaced with the five row longitudinal system
(completed in 1966). The biggest problem of the plant was the obvious
inability to transfer the oxygen required by the high strength wastewater
entering the aeration tanks. The ill-fated introduction of tube diffusers
and tapered aeration was an attempt to correct the oxygen transfer problem
in the most economical manner.
51
-------
TABLE 7
East Plant Loading 1936-1981
Screened Sewage
BOD , Suspended Solids
Year . Flow (MGD) (PPM) (10J x 1b) (PPM)(10J x 1b)
1936 38.65 176.9 57,022 261.0 84,131
1937 40.84 166.0 56,541 278.0 94,688
1938 . 44.99 160.2 60,110 256.0 96,056
1939 45.10 179.7 67,591 271.0 101,932
1940 44.09 256.0 94,134 290.0 106,636
1941 51.17 277.1 118,255 302.0 128,881
1942 56.32 307.4 144,389 299.0 140,443
1943 56.53 302.1 142,428 295.0 139,081
1944 54.15 335.6 151,561 310.0 139,999
1945 -56.02 332.3 155,253 315.0 147,170
1946 55.56 366.0 169,594 317.0 146,888
1947 59.16 336.0 165,781 297.0 146,538
1948 58.38 334-.0 162,621 304.0 148,014
1949 56.99 316.1 150,241 333.0 158,274
1950 57.19 304.8 145,379 309.0 147,382
1951 65.21 300.7 163,536 290.0 157,717
1952 91.08 295.5 224,464 289.0 219,527
1953 86.78 282.6 204,530 297.0 216,400
1954 89.54 270.8 202,224 288.0 215,068
1955 96.88 281.3 227,285 280.0 226,234
1956 90.53 290.0 218,956 284.0 214,426
1957 87.04 323.8 235,051 271.0 196,723
1958 83.22 316.8 219,877 263.0 182,536
1959 94.34 276.2 217,313 266.0 290,288
1960 101.13 252.6 213,049 265.0 223,507
1961 96.46 276.8 222,679 265.0 213,186
1962 95.30 291.4 231,605 273.0 216,981
1963 88.86 317.4 235,223 306.0 226,774
1964 89.69 307.2 229,790 294.0 219,916
1965 103.40 293.0 252,670 307.0 264,743
1966 108.90 293.0 266,110 301.0 273,376
1967 109.00 297.0 269,991 304.0 276,354
1968 107.20 306.0 273,579 314.0 280,731
1969 105.20 239.0 209,691 227.0 199,163
1970 94.20 208.0 163,411 206.0 161,839
52 - :
-------
TABLE 7-continued
Year
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
Flow (MGD)
100.00
96.00
92.20
85.40
78.00
81.60
78.00
79.80
79.00
73.00
74.00
Screened
BOD ,
~~ (10 x
(PPM)
Sewage
Suspended So14ds
/ 7^ / 1 ~rtw"
220.0
218.0
261.
302.
.0
.0
347.0
326.0
329.0
313.0
290.0
291.0
273.0
183,480
174,540
200,695
215,095
225,730
221,857
214,021
208,312
191,069
177,167
168,485
197.0
220.0
292.0
264.0
283.0
312.0
342.0
352.0
326.8
298.8
244.3
x 1b)
164,298
176,141
224,533
188,030
184,097
212,330
222,478
234,267
215,315
181,915
150,772
53
-------
In defense of the Milwaukee Sewerage District personnel who were
involved in the provision of this facility it must be pointed out that
economics had a great influence on the East Plant. It was conceived and
partially constructed during the Great Depression over the veto of the
mayor of the city of Milwaukee (1930 - 1935).
When the addition was proposed in 1947 economics again played a major
role as evidenced by the rejection of additional air compressors. At that
point the Commission was faced with a massive flood control program to
prevent flooding of sanitary sewers and basements as well as the rehabili-
tation of portions of the original West Plant constructed in 1923-1925.
The increasing population of the service area and the industrial
contribution to the collection system as well as regulatory agency pressure
to improve water quality in the District led to the provision of the
expanded service area and construction of the new South Shore Plant to
ultimately relieve the load on the entire Jones Island facility.
Decisions had to be made to allocate the limited available funds and
until the East Plant aeration system became a major liability following the
tube diffuser installation and return sludge separation, most of the funds
were used in other areas.
54
-------
MILWAUKEE, WISCONSIN SOUTH SHORE WASTEWATER TREATMENT PLANT
AERATION HISTORY, 1974-1988
INTRODUCTION
In 1951 the Sewerage Commission retained the consulting engineering
firm of Alvord-, Burdick and Howson to study the future needs of the
existing and potential service area of the District.
The Commission, in December 1957, retained Alvord, Burdick and Howson
to design the new sewage treatment plant and intercepting, main, and relief
sewers. On March 2, 1959, the consultants proposed initial construction of
a primary treatment plant with addition of activated sludge secondary
treatment at a later date.
In January 1960, following receipt of preliminary approval from the
Wisconsin State Board of Health, the Commission authorized
...the consulting firm of Alvord, Burdick and Howson, to
proceed with the detailed engineering layout for a 120
M.6.D. complete activated sludge treatment plant at the
Puetz Road site with construction of a 60 M.G.D. primary
plant as the first phase thereof and, also, to proceed with
the preparation of plans and specifications for contract
proposals to be received for construction of the 60 M.G.D.
primary plant with disinfection of plant effluent, subject
to approval of the Commission and the Wisconsin State Board
of Health. (1960 Annual Report, Page 47)
The primary treatment facility was placed- in service in December 1968.
The activated sludge secondary plant startup began in September 1974. It
should be pointed out that the District's plant engineering and operating
staff were involved with design of both the primary and secondary facil-
ities.
The activated sludge portion of the facility incorporated much of the
technology developed at the Jones Island plant. The general plan of the
plant is shown in Figure 8. ;
AERATION TANKS
The original South Shore Treatment Plant aeration facilities consist
of four (4) batteries of six (6j flat bottom single pass aeration basins
30 ft. wide, 370 ft. long with a water depth of 15 feet.
Each tank contains 2,448 1 ft. square 1 1/2 inch thick Filtros silica
plates with permeabilities varying from 15 to 21. The plates are in nine
(9) plate concrete containers arranged in a staggered 8 row longitudinal
placement pattern. Each plate container is offset to insure that the
container piping is identical in length and configuration. The offset
introduces aspects of the transverse placement pattern to the aeration
pattern (See Figures 9 andio). The ratio of aeration tank surface to plate
surface is 4.5 to 1. Figure 11 shows the overall process air system serving
the 24 aeration tanks.
55
-------
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Figure 8. General Plan of South Shore Wastewater Treatment Plant
56
-------
LOW PRESSURE AIR
9 PLATES
PER
HOLDER
Figure 9. Schematic diagram of the diffuser holder arrangement in
the South Shore aeration basins.
57
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59
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Air piping is arranged to allow feeding the plate containers from the
aeration tank headers on each side of the aeration tank if desired.
Normal operation is to add air from one tank header utilizing the
header valve to control the measured air volume to each aeration tank. A
total of 144 plates are thereby serviced by each 6 inch downcomer.
The 6 inch knife gate valves on each downcomer are used to provide the
desired air distribution in each section of the aeration tank.
Dissolved oxygen probes are used to measure the oxygen content of the
mixed liquor at the end of each aeration tank. Since 1977 when the second-
ary plant computer control was placed on-line, air to each aeration tank
was computer-controlled based on the dissolved oxygen concentration.
The computer control system also adjusts the mixed liquor solids in
the aeration tanks by controlling the volume of return sludge to each
aeration tank.
The aeration tanks are designed to operate in the conventional plug
flow or the step aeration mode (See Figure 12). The tanks can be operated
in either mode at plant flows below 120 M.G.D. At flows between 120 and
240 M.G.D., the step aeration mode must be used. Figure 13 shows the
primary effluent distribution to the 24 aeration tanks.
PROCESS AIR SUPPLY
The process air for the aeration tanks is provided by four (4) All is
Chalmers single stage centrifugal blowers with capacities of 35,000 CFM
each. Each blower is connected to a White Superior 12 cylinder 1375 B.H.P.
900 rpm, spark ignition gas engine designed to operate on natural or
digester gas at 35 psig. Falk Company speed increasing gear is used to
bring the blower speed up to operating speed of 4930 rpm.
The inlet air is drawn through large louvered and screened intakes
into an intake duct and on through a series of cloth filter bags or sacks.
Initial operation included coating of the sack interior with asbestos
filter aid to increase dust removal efficiency. The use of filter asbestos.
aid was discontinued in 1979 and the system now uses solka flbc (cellulose
fibre) as a filter aid with cloth bags for air filtration. Filter cleaning
equipment utilizing motorized shaker mechanisms is provided.
The compressed process air is transported 645 feet to ;the aeration
basins located at the lower plant elevation in a 90 inch diameter steel
pipe.
60
-------
FIGURE 12
t
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FACILITY EXPANSION
As part of the South Shore Treatment Plant expansion, four (4) addi-
tional aeration basins utilizing Sanitaire gas cleaned ceramic diffuser
discs have been added along with eight (8) additional final clarifiers. A
total of 2496 round 8.7 inch diameter 3/4 inch thick diffusers with perme-
abilities ranging from 20.8 to 31.2 are installed in each aeration tank.
The diffuser material is reported to be Alumina. This arrangement provides
full bottom coverage with a ratio of aeration tank surface to diffuser
surface of 10.9 to 1. As of this date (April 1988), these new facilities
have not been placed in service.
PLANT PERFORMANCE 1978-1987
Table 8 shows the plant operating data for the period 1975 through
1987. The low aeration tank loadings and air use per gallon of sewage are
due to the low BOD content of the primary effluent. Iron addition (pickle
liquor) to enhance phosphorus removal was included in the original plant
design. From the startup in 1974 through 1979, pickle liquor was added to
the aeration tanks. Iron addition was transferred to the primary tanks in
1980 and appears to have reduced the air requirements in the aeration
system.
No aeration basin cleaning was done on a regular basis following
initial start up in 1974. Aeration tanks were taken out of service and
water washed when it was necessary to drain aeration tanks. The most
serious problem in the aeration tanks involved the removal of all plates
from one tank (1974) to remove the wrapping left under each plate by the
installing contractor.
In March 1976, the entire underground portion of the South Shore
primary and secondary plants was flooded. The subsequent rehabilitation of
the facilities (pumps, motors, meters, etc.) dictated the cleaning schedule
for the aeration tanks during the following two years.
Cleaning records are available from 1981 through 1987 and are
summarized in Table 9.
Prior to 1981, plant personnel working with the Research Department
experimented with water wash cleaning using high pressure water jets,
scarifying with a rotating wire brush, sandblasting and acid treatment
followed by" water wash (Milwaukee method). Both acid cleaning and
scarifier cleaning were found to be capable of restoring the normal air
pattern in the aeration tank.
Table 9 shows a wide variation in frequency of aeration tank cleaning
over the seven (7) year period. The most tank cleaning occurred in Battery
#1 (Aeration Tanks 1-6) and is related to the plant expansion program which
required draining of aeration tanks to allow the new construction. The
history of the aeration tank cleaning is also related to the installed
plaint capacity of 120 MGD and actual average annual daily flows as low as
62 MGD (Table 8). Aeration basins were removed from service during low
flow periods.
63 '
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64
-------
TABLE 9
.South Shore Aeration Tank
Cleaning Record 1981-1987
Basin. No. ' Year Washed Year Acid Washed Year Scarified
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
81,
85,
81,
86,
81,
83,
81,
85,
81,
82,
82
81,
81,
81,
81,
81,
82,
82,
82,
82
81,
81,
81,
81,
81,
81,
82,
85.
83,
86,
82,
85,
82,
86
82
86,
81
82,
82,
84,
84
83
83,
86,
86
83,
84,
82,
86
82,
85, 85
83, 85, 85,
87
83, 85, 86
85, 86
83, 85,
86
83
83
87
83
86
86, 86
86
84, 86
83, 86
81
85
81, 83, 86, 86 83, 85
81, 83, 86
86
81, 86 82
81
82, 86, 86
82
81
81 '
81
81
si ;
82
82 83 :
82
82
1
81, ,86
i
81
81
81
81, 86
65
-------
Tanks taken out of service were originally drained, washed, and left
empty. Plate clogging then occurred due to algae development on the
plates.
The aeration basin operating experience is discussed in more detail in
the attached three page summary provided by Mr. Joseph R. Grinker, South
Shore Process Control Supervisor. (Appendix A) \
66
-------
APPENDIX A
Milwaukee Metropolitan Sewerage District
735 North Water Street Milwaukee, Wisconsin 53202-4151
414-272-5100
7/8/88
Lawerence A. Ernest P.E.
5955 N. Lake Dr.
Milwaukee, Wisconsin' 53217
Dear Larry,
Find attached ray summary of observations on use of the existing 24
aeration basin since startup. The summary is not extremely detail-
ed nor inclusive of all considerations that could be addressed, how-
ever, I hope it gives you what you are- looking for. If you wish
to extract portions of the summary for your report feel free to do
so. As always, call Henry or I if you are unclear on any of the
subject summarized.
Yours Truly
seph R. Grinker
cc: H. Dedinsky
J. Schlintz
J . Quandt
bs
67
-------
SOUTH SHORE WWTP AERATION BASIN
OPERATING EXPERIENCE
( 1974-1988)
JOSEPH R. GRINKER
Introduction
The South Shore WWTP is designed to effectively treat 120 MGD. The
24 aeration basins (370 ft. x 30 ft. x IS ft. SWD) were placed into
service in September. 1974. Each basin contains 2448 1 ft. square
1% inch thick Filtros silica plates. All these plates are fine
bubble diffusers with permeabilities ranging from 15 to 21.
The purpose of this summary is solely to highlight some of the
operating experience with these basins. In particularj basin
idling and rejuvenation techniques will be discussed.
Past Aeration Basin Idling Experience
As is the case at all treatment plants, facilities are designed for
the future flows or loadings at maximum, hour, day or week, depend-
ing on the step in the process. . ' ;
This results in excess capacity during normal conditions and re-
quires taking basins out of service to provide proper treatment
periods.
In Wisconsin, where freezing conditions exist one-half of the year,
precautions are necessary to prevent damage to idled basins. The
experience South Shore personnel have gained since the;mid 7Q's
for obtimum conditions to idle inactive basins has been substantial.
Initially, the practice of taking a basin out of service, winter or
summer, was to close primary effluent and return sludge feed valves
and leave filled with mixed liquor. The air valve was put on local
and reduced to a flow rate which provided action over most of the
basin. This has the advantages of :
1. Least amount of labor to take out of service
2. Least amount of labor to place back in service
3. No substantial level change if basin has to be
placed in service with ice formation on the
surface
4. No concern of frost problems at lower tank levels
68
-------
Summary
Page Z
1974-1988
The main disadvantage of idling the basins full of mixed liquor are:
1. A large volume of poor quality mixed liquor will
pass through the final clarifiers when placed in
service and a chance of solids settling onto diff-
users if air flow is left too low.
During summer months, when basins are taken out of service for
routine cleaning and/ or repair, often they were allowed to re-
main completely empty and dry except for raimvater additions.
Experience has shown that even though these basins are great for
odor control when dry and they provide good visual effects for
tour groups, leaving in this condition has resulted in the most
problems. This is true if left in this condition for periods of
more than one or two weeks.
The problem of keeping the basins completely empty is, when no
liquid is available to provide head, air flow is usually turned
off completely because it is difficult to control as header pres-
sure changes. Then, when rain occurs, an algae develops across
the basin bottom. Unless the basin bottom is completely covered,
air flow is of little value because it will not disperse uniformly.
Depending on weather'conditions, the thin layer of algae filled
water may evaporate completely and dry onto the diffuser plates.
This cycle can occur several times before the basin is placed
back into service. The result is a major clogging of the.diff-
user pores in an otherwise cleaned basin. Experience has shown that
more than ^50% of the basins left in this condition will not
perform, effectively when placed into service. Effective treatment
in many basins left in the dry state for a month or more could
only be accomplished by acid washing.
Efforts to rejuvinate basins that remained flat and poor mixing
patterns, the following procedures were used: ;
1. Lowering the basin level 2-4 feet for short periods
to increase air flow and temporarily
2. Increasing overall header pressure
These efforts were marginally successful on basins with diffusers
that weren't extremely plugged. Most of the basins left dry, even-
tually required cleaning with muratic acid.
69
-------
J. GRINKER
SUMMARY .
1974-1988
PAGE 3
Cleaning basins with a gasoline powered scarifier (steel wire belt)
has some degree of success. Its effect can be seen visually by
running the scarifier over a section of diffusers which are par-
tially blocked. With air flow on to the basin and about h inch of
water covering the diffusers, the pattern of air through each dif-
fuse has been observed as poor to extremely good as the scarifier
passed over it. The question of whether the scraping action of the
scarifier tends to close some of the pores is not clear. It is ;
proven however, that both acid cleaning and scarifier cleaning :
usually will restore a basin back to norm-al. In one or two cases,
a second acid cleaning was required before a normal air pattern
was established.
Present Aeration Basin Idling Method ,
After having spent considerable time and labor restoring aerations >
.basins that were idled dry, it was decided that about the only time
we should leave them in that state is during.-repair periods. The
practice now is, when a basin is taken out of service, it is pumped
down about % way. This allows enough head to keep a reduced air
flow, while reducing the volume of. poor quality mixed liquor stored
in the system.
The two main disadvantages to this are:
1. Some odor is emitted from aerobic MLSS
2. Care must be taken not to allow basin level changes
if heavy ice layer exists.
Very few basins idled in this condition have required extra effort
to obtaiin normal air flow when placed into service.
Some efforts were made to idle basins with final effluent or pri-
"mary effluent. No convenient arrangement exist to quickly fill as
basin (1.25MG) with final effluent. About the time several were
filled when this was tried once, they had to be put back in service
due to high flow conditions. Use of primary effluent for idled
basins is objectionable because even at reduced air flows, white
billowing foam is formed. Wind blows this foam about the plant
resulting in poor aestetic conditions.
Conclusions
We. may not have all the problems solved in dealing with fine bubble
diffuser operation, however in our 13 plus years we have learned
how to use the system with the minimum amount of labor for cleaning
and idling basins. :
70
-------
MILWAUKEE, WISCONSIN JONES ISLAND EAST PLANT
AERATION TANK RENOVATION HISTORY, 1982-1988
INTRODUCTION
As part of the multi-billion dollar Milwaukee Water Pollution Abate-
ment Program, begun in 1976, the consulting Engineering firm of CHJ1 Hill
developed the detailed plans for the renovation of the Jones Island Plant.
The major changes in the plant involved the provision of primary
clarifiers to replace the fine screens and to increase plant peak capacity
to 300 M.G.D., which would handle highflows during periods of high runoff
arid subsequent pump out from the deep tunnel storage facilities.
Primary effluent will be fed to all aeration facilities, reducing the
BOD and suspended solids additions. To accommodate the increased flows,
additional final clarifiers will be required. Figure 14 shows the Jones
Island treatment facility projected to be completed in 1996.
The extent of change of the Jones Island facility can be seen by
comparing the 1974 plant (Figure 15) with the projected final facility
(Figure 14).
The rehabilitation of the East Plant aeration tanks and construction
of the new mixed liquor feed channel began in 1982. As the aeration tanks
were modified, they were returned to service as two pass tanks. Upon
completion of the new mixed liquor channels, the tanks were converted to
the single pass mode in 1985.
NEW EAST PLANT AERATION TANKS
With the exception of aeration tank #1 and #2, all aeration tanks
retained their original dimensions providing single passes in each tank
22 ft. wide by 370 ft. long.
The five row longitudinal plate placement pattern in the flat bottom
tank was retained. Piping was provided in each pass for tank cleanup in
addition to a trench along one side to flush solids from the tank during
cleanup. All new plates, plate holders, and air piping was provided. The
plates installed were Norton ceramic plates 1 ft. square 1 " thick with
permeabilities varying from 17 to 23. ;
The diffuser plates needed for both the East and West Plant
rehabilitation (110,100 Plates) were purchased via competitive bids under
Contract No. J42E12. Plate materials were specified as follows:
B. Materials
All diffuser plates shall be one, but. not both, of the
following types:
1. Silica plates, which shall be composed of grains
of substantially pure silicious sand, bonded with
silicate glass, after being kiln-fired at a high
temperature.
71
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2. Alumina plates, which shall be composed of grains
of crystalline aluminum oxide, bonded with high
alumina glass, after being kiln-fired at a high
temperature.
All diffuser plates shall be free from any ingredients
or processes of manufacture which will cause leaching,
clogging or disintegration when the plates are continu-
ously immersed in and supplying air to sewage, mixed
liquor or sludge. Grain size shall be uniform.
All diffuser plates shall be 12 inches square within a ,
tolerance of plus or minus 1/8 inch. Silica plates
shall be 1-1/2-inches thick within a tolerance of plus
or minus 1/16-inch. Alumina plates shall be 1 inch
thick within a tolerance of plus or minus 1/16-inch.
The permeability of each diffuser plate shall be 17.0
to 23.0 scfm per square foot, inclusive. The perme-
ability shall be as specified hereinafter.
The Norton proposal dated May 7, 1982, indicated that the plates to be
furnished were
Alumina plates which shall be composed of grains of
crystalline aluminum oxide bonded with high alumina
glass after being kiln fired at a high temperature.
The following description of the new aeration facilities is taken from
a Jones Island report written by Robert Moser, dated March 25, 1986:-
DESCRIPTION OF SINGLE PASS OPERATION
East Plant RAS and raw sewage are mixed just east of
the flow control structure in the Mix Channel. The Mix
Channel conveys the mixed liquor to the new East Plant
Mixed Liquor Feed Channels which have a combined volume
of 3.7 M6 and are aerated by fine bubble diffusers.
Each channel has a 36 inch pipe and a basin feed gate
valve in the aeration basin Flow Control Box, which
supplies mixed liquor to each aeration basin. The East ;
Plant has twenty (20) aeration basins. A typical
aeration basin is shown in Figure 3. Mixed Tiquor flow
is regulated by the Flow Control Box Weir Gate
(G-5-55-X) and measured by a staff gauge and admittance
probe in the Flow Control box. The admittance probe
was not operational during this time period. The mixed ;
liquor in the south pass flows over an outlet weir
(effluent box) and crosses over to the north effluent
box via 36 x 36 inch hole in the wall separating the
passes. The flow is conveyed to the East Plant clar-
ifier feed channel (east) by an existing 36 inch pipe.
This 36 inch pipe includes a venturi meter.
74
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Air to each basin is supplied by a 20-inch line origi-
nating in the Aerated Effluent Gallery. Within the
gallery, a 16-inch flow tube (FE-5-58-X) monitors the
air flow, and a 16-inch pneumatically-operated butter-
fly valve (FCV-5-58-X) can be used to adjust the air
flow to the basin. Air flow (0-5, 500 scfm) is indi-
cated locally for each basin. The main 20-inch line
then exits the gallery and travels down the basin
centerwalkway.
Along the center walkway are six downcomers which take
air to a dedicated area (zone) within the basin. Each
8-inch, downcomer has an 8-inch flow tube (FE-5-60-X-1
thru 6) and a manually-operated butterfly valve ; to
monitor and control the air flow to each zone. Air
flow measurement is accomplished by using a portable
air flow meter (0-1,500 scfm). Each zone served by a
downcomer consists of a looped distribution system and
a condensate blow-off line which is operated from the
center walkway. A basin contains approximately 2,900
fine bubble diffusers plates. The diffuser plates are
in nine (9) plate containers and the containers are
arranged in a five-row longitudinal' pattern on the
basin floor. The total number of plates per zone (two
halves - North and South Pass) is listed below.
0 Zone 1 = 1,116 plates or 558 in each half..
0 Zone 2 = 900 plates or 450 in each half.
0 Zone 3 - 892 plates or 446 in each half.
Basin 1 contains 707 plates (Total) in Zone 1 and basin
2 has 1,098 plates (Total) in Zone 1.
The dissolved oxygen (D.O.) concentration is continu-
ously monitored for each aeration basin. The D.O.
probe is connected to one of three (3) plug-in junction
boxes (AN-5-57-X-1 thru 3) on the North Pass. The D.O.
probe location and concentration is displayed on three
(3) local control panels.
Each aeration basin is served by three (3) local
control panels (LCP's): 268-LCP-5-Y-2 in the Mixed
Liquor Gallery, and 219-LCP-X and 268-LCP-5-Y-1 in
Aerated Effluent Gallery. Each 268-LCP provides
monitoring and control functions for two (2) aeration
basins and a 219-LCP is dedicated to each aeration
basin. The monitoring and control functions of each
LCP is shown below:
75
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Mixed Liquor Gallery Aerated Effluent Gallery
Parameter 268-LCP-5-Y-2 268-LCP-5-&-1 219-LCP-5-X
D.O. Cone., mg/1 x x x
0.0. Probe Location x x x
Basin Air Flow, CFM x x
Air Flow Totalizer x
Instrumentation for
16-inch Valve x
Mixed Liquor Flow x x
Flow Totalizer . x
It should be noted that the new aeration tank design provides for
tapered aeration since the air is distributed to the three (3,) zones (see
Figure 16).
Each standard aeration basin (3-20) contains 2908 plates. The ratio
of theoretical aeration tank surface to plate surface is 5.7 to 1.
As indicated earlier in Mr. Robert Moser's description, aeration
basins 1 and 2 contain fewer plates in the first aeration zqne since the
original tanks were modified to provide the new mixed liquor feed channel.
The original raw mixed liquor feed channels will be used to convey
some of the mixed liquor from the aeration tanks to the twelve (12) new
East Plant secondary clarifiers that will be added. The existing ten (10)
East Plant secondary clarifiers will remain in service.
PROCESS AIR SUPPLY
The renovated East Plant and the existing West Plant are supplied with
process air from the equipment installed in 1973.
The four air compressers, each capable of supplying 110,000 CFM at
10 psig, are powered by 5500 HP 4160V synchronous motors. Tfie electric
power required is supplied by the on-site gas turbine generators with
backup by the electric utility, thereby guaranteeing 100% reliability.
The air filters consist of four (4) Rollo-Matic air filters (mats)
followed by four (4) electro static agglomerators followed by bag filters.
AERATION TANK DISTRIBUTION'
The change in air distribution in the aeration basins has reduced the
number of down headers to six (3 per pass) in contrast to the 35 provided
in the original modified ridge and furrow in the East Plant.
PLANT PERFORMANCE !
Changes in operation of the East Plant aeration facilities necessary
to keep the Jones Island plant in operation and meet discharge permit
76 ;
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requirements have continued since the aeration tank renovation began in
1982. Conversion to single pass operation was begun in June, 1985. The
Jones Island primary settling tanks were initially placed in operation in
November, 1986, removed from service in March, 1987, due to a flood,
returned to service in April, 1987, and again removed in June, 1987, due to
a secondary clarification problem. The tanks were again returned to
service in November, 1987, and continue in service. Since the sludge line
to the South Shore plant is not yet completed, Jones Island primary sludge
is being returned to the secondary treatment process. \
In August 1982, trucking of raw waste activated and digested lagooned
sludges from the South Shore plant to the Jones Island Plant was initiated.
The South Shore lagooned sludge is incorporated into the Jones Island
aeration tanks and ultimately incorporated into Milorganite.
When the East Plant plate clogging problems occurred in the renovated
aeration basin in 1983, the digested lagoon sludge was removed from the
East Plant and confined to the ridge and furrow aeration tanks in the West
Plant. The South Shore waste activated sludge is normally processed
directly into the Milorganite processing stream.
The changes in plant operation over this period (1982-1988) make it
virtually impossible to analyze annual plant operating data.
When the twelve mile, four-barrel, interplant solids pipeline is
placed in service between the Jones Island and South Shore Plants and the
rehabilitation of the Jones Island West Plant is completed, it will be
possible to operate the East Plant as redesigned and evaluate the
efficiency of the new aeration basins.
Tank cleaning since the initial plate installation beginning in 1983
was also influenced by the frequent operation changes referred to above as
well as other factors. :
When the plates were initially installed and the tanks were returned
to service as two pass tanks, two major problems developed:
1. plates separated from the containers and had to be regrouted,
2. clogging problems developed. ;
The plates installed in the first eight (8) aeration tanks (1, 2, 3,
4, 5, 7, 8, and 9) began to break out of the containers shortly after
initial start up in 1983, and the tanks were taken out of service and all
plates removed and regrouted. Litigation between the contractor, the
District, and the consultant resulted.
Plate clogging in the rehabilitated basins occurred as soon as the new
basins were returned to service in the two pass mode in 1983. Ewing
Engineering Company was retained by the primary consultant, CfLM Hill, to
study the problem and they conducted a study during the pieriod May-
December, 1983. ;
78
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The conclusions and findings taken from the April 16, 1984 report of
the Ewing Engineering Company were as follows:
1. The Jones Island East Plant rehabilitation, as now
operated, is an interim operation. When construc-
tion of the entire plant is completed, the condi-
tions that the aeration basins are then exposed
to, (waste pickle liquor, organics, grit and
suspended solids), will be much less severe than
that at present.
2. In the final design, waste pickle liquor will be
oxidized with chlorine and added to the wastewater
ahead of the primary clarifiers. Thus, the
aeration basins when operated as per the final
design, will not experience iron concentrations at
the high level observed during these tests.
3. The Jones Island Plant final design never consid-
ered the possibility of adding agrilife, (South
Shore lagoon sludge), to the aeration basfns.
Because agrilife contains a high concentration of
iron, sulfur and grit, it is believed to adversely
influence the diffuser plate fouling phenomenon.
4. Completion of the construction phase is expected
to yield improved performances in so far as
diffuser plate fouling is concerned. :
5. South Shore data gives indication that 20 perme-
ability plates are well suited to the design
application. :
6. The rate of fouling in the Jones Island East and
West Plants is significantly greater than that
observed in a number of other municipal wastewater
treatment plants.
7. East Plant operation has indicated the apparent
practicality of operation during the winter with
little or no maintenance.
8. Microscopic examination of silica, alumina, and
Norton diffuser plates indicate no visually
perceptible difference in physical characteristics
of these materials. The granular structure and
pore size of these plates appear very similar.
9. The Norton plates show similar reductions in
strength, as a result of soaking in water and
hydrochloric acid solutions, as has been observed
for Filtros Alumina plates we have tested.
79
-------
1-0. The rate of fouling and composition of foulant on
silica, alumina and Norton does not appear to be
significantly different.
11. There is a basic difference between the accumu-
lation of foulant residue per unit area on dif-
fuser plates located at the inlet versus the
discharge end of an aeration basin. Foulant
accumulation on plates at the outlet end is
perhaps one-tenth the rate of the inlet end.
There appears to be a general correlation with
decline in organics and unoxidized iron from the
inlet to the outlet end of a basin.
12. Based on plenum test work, the nature of and
quantity of foulant East to West is not signifi-
cantly different.
13. Most of the acid soluble constituents measured
appear to be calcium and magnesium coupounds,
presumable carbonates, when deposited. ,
14. Virtually none of the iron compounds in the
non-volatile foulant residue appear to be soluble
in acid a applied.
15. The role of significance of the substantial
quantities of silica or sand found on all fouled
test diffusers in unknown.
16. Increases in pickle liquor feed in and of its own,
can have a dramatic affect on the rate of diffuser
fouling, based on both plenum and full-scale
observations.
17. Reduced usage of pickle liquor to that required
for phosphorus removal will likely result in
reducing maintenance requirements of the system
compared to present operation.
18. The present design simplifies tank draining and
cleaning over previous design. (Flat floor,
gutter, and no obstruction).
19. The present diffuser plate cleaning procedures
appears very effective in restoration of plates
and OTE capabilities.
20. Higher permeability may be less susceptible to the
adverse effects of fouling. OTE capabilities
unknown.
80
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21. The effect that unit air flow rate has on fouling
rate is unknown and should be investigated.
22. It appears high air flow rates, (e.g., 2 cfm/sq.
ft.), at least in the first grid, may prolong
periods between required plate maintenance.
23. A decline.in the ratio of DWP to mean BRV, when it
occurs, is due to the relative increase of BRV
with respected to DWP, with the attendant effect
that progressively less of the diffuser area
actively emits air. Since higher flux rates are
known to result in the formation of larger bub-
bles, decreases in oxygen transfer efficiency may
be expected.
24. The District has the capability of conducting
similar studies with the DWP and BRV methods and
equipment that has been provided to them.
25. We do not know the relative merits of oxidized
pickle liquor versus unoxidized pickle liquor
addition as it regards diffuser plate fouling.
Additional research appears to be warranted in
this area.
26. The Jones Island process, when construction is
completed, will be substantially identical to
South Shore.
27. On tha basis of OTE data, old West and East Plant
aeration tanks were significantly fouled at the
time the East Plant basins were rehabilitated.
28. Diffuser fouling appears to significantly reduce
aeration efficiency.
29. The off gas OTE data of the fouled Jones Island
basins is substantially better than that expected
from other generic devices including jet aerators,
coarse bubble aerators, fine bubble tubes and
static aerators.
30. Based on analysis of old East Plant plates, from
Tank 3, it is apparent that severe fouling has
occured over the past 20 years, despite whatever
maintenance was given to the plates. Complete or
near complete plate restoration of plates fouled
to this degree seem unlikely.
31. As plates foul, the rate of fouling appears to
progressively decrease.
81
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Plant operating experience following the Ewing report was summarized by
Robert Moser, Jones Is'land Process Control Supervisor.
Jones Island WWTP East Plant Aeration Basin
OPERATING EXPERIENCE (1985 - 1988) l
INTRODUCTION
The attached memo covers actions needed to place an
aeration basin into service after it has been idled/
cleaned. Generally after an aeration basin is placed
into service it is maintained at 5,000 CFM (or greater)
for several days. On several instances where less than
5,000 CFM has been maintained, fouling problems have
been encountered in zone I (Basin Inlet Zone). Afer
several days, the aeration basin air flow is allowed to
vary with other aeration basins in response to D.O.
level (2-4 mg/1).
The minimum air flow is 3,500 CFM for an in-service
aeration basin. At air flows less than 3,500 CFM,
problems have been encountered with fouling. The
pickle liquor mass feed rate is maintained at less than
6,000 Ibs/day (about 5.5 GPM) to prevent fouling. This
level was set in 1984. Problems have not been encoun-
tered with high plant effluent phosphorus levels. The
following summarizes other operation procedures and
experiences for the basins. These include moisture
removal from containers, basin idling, and rejuvenation
techniques.
Moisture Removal From Containers (Diffuser Plates)
Each basin contains six (6) blowoffs (two per zone) for
removing moisture from the containers. Three (3) main
header blowoffs are also provided. The colder months
(late fall, winter, and early spring) little, if any,
water is found in the containers. During this period,
the blowoffs are checked about once a week or less
often. During the warmer months (late spring, summer,
early fall) a significant amount of water is found in
the blowoffs. The greatest amount of water is found in
zone I and lesser amounts in zones 2 and 3. The basins
during the warmer months are blown down several times
per week. If the basins are not routinely blown down,
a significant increase in PAC backpressure will be
observed. In severe cases where a blowoff has not been
operated frequently enough, it is necessary to increase
the air flow to a zone, to remove the accumulated
water. Normally a blowoff is left open until no water
is present in the air. The maximum number of blowoffs
open at any given time should not exceed four (4).
This is done to prevent excessive air wasteage from an
aeration basin. 32
-------
Aeration Basin Idling
* Winter Months: During the winter months, aeration
basins are normally idled with mixed liquor to a
depth of about five (5) feet. This level was
selected to protect the W3 (Plant Effluent) valves
and piping from ice damage and freezing. Roughly
2,500 CFM of air is maintained on the basin.
* Summer Months: Aeration basins are normally idled
with W3 during the summer months. A W3 depth of
about 3-1/2 feet and an air flow of 2,500 CFM ;is
maintained in the aeration basin. "Aqua-Shade"
has been used in the aeration basins since summer,
1985, to retard the growth of algae. "Aqua-Shade"
is a dye, which absorbs the blue-green light spec-
trum used by algae for photosynthesis, and there-
fore, retards their growth.
It is applied at 1 mg/1 and checked periodically
(i.e. monthly) for proper strength using an
artificial worm - fishing lure. "Aqua-Shade" is
added as needed to maintain a 1 mg/1 concentra-
tion. We have not encountered any problems with
algae causing difusser plate plugging, when an
idled aeration basin is put back into service.
Rejuvenation of Aeration Basins
We have encounterd severely fouled aeration basins
(zone 1 ONLY) during Fall, 1985 and early Summer, 1988.
The Fall, 1985 fouling problems were due to the pickle
liquor feed rate, which was greater than 6,000 Ibs/day.
The early Summer, 1988 problems was due to low total
basin air flow (less than 5,000 CFM) at start up after
basin cleaning and acid washing. Of the aeration
basins which required rejuvenation (1985 and 1988
episodes), only one (1) aeration basin has required
re-cleaning and acid washing (Basin #5 - 1988). During
a fouling episode the total air flow to the aeration
basin will remain the same or decrease only slightly.
The total air flow distribution to each zone, as
measured with a portable air flow meter, is impacted as
follows:
* ZONE 1: Airflow is greatly reduced to North/South
Pass. Only in zone 1 have we ever observed
fouling problems during the three (3) year period.
* ZONE 2 and 3: Air flow is greatly increased well
beyond what is expected..
83
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The Rejuvenation procedure is directed at reducing air
flow in Zones 2 and 3 to acceptable levels and trying
to maintain high basin total air flow (i.e. 5000 CFM)
regardless of D.O. level. This procedure forces air
into zone 1. Zone 1 must be monitored closely, and
the all butterfly valves adjusted as needed to ensure
proper air distribution between zones and the north and
south passes. The air flow in each zone and total air
flow is monitored daily (Mon - Fri) by the Process
Control Co-ops, and adjusted as needed. Generally,
after 1-2 weeks the air flow reaches the proper zone
distribution (refer to attached memo) and the procedure
is stopped. This procedure has been extremely success-
ful.
Review of the operating and maintenance problems of the renovated East
Plant aeration tanks indicated one major item that had not been investi-
gated - the ceramic material in the Norton plates provided under Contract
J42E12. ;
Data on various ceramic plates previously tested by the District are
shown in Tables 10 and 11, taken from an internal report dated June 1, 1956.
. When two Norton plates furnished under Contract J42E12 were found to
weigh ten (10) pounds instead of the expected twelve (12) pounds for
alumina plates, laboratory analysis was requested.
Results of the analysis indicate the plate material is mainly mullite
(3Al203'2Si02). This analysis, received on 9/28/88, confirms that the
Norton plates do not meet the specification of the contract or conform to
Norton proposal dated May 7, 1982.
i
The resolution of this discrepancy is in the hands of the M.M.S.D. and
its principal consultant, CH?M Hill. Based upon the laboratory results, it
must be concluded that the Norton plates installed in the Jones Island East
Plant during the renovation contain "major amounts of mullite
(3Al?0,'2SiO?) and minor amounts of alumina (A190,)" (Erlin, Hime Asso-
ciates report dated September 19, 1988). c J
84
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