'ATE
WATER POLLUTION CONTROL RESEARCH SERIES • 17O5ODNW05/70
INVESTIGATION OF THE USE OF
HIGH PURITY OXYGEN AERATION
IN THE CONVENTIONAL ACTIVATED
SLUDGE PROCESS
U.S. DEPARTMENT OF THE INTERIOR • FEDERAL WATER QUALITY ADMINISTRATION
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Reports describe the
results and progress in the control and abatement of pollution
of our Nation's waters. They provide a central source of
information on the research, development, and demonstration
activities of the Federal Water Quality Administration,
Department of the Interior, through in-house research and grants
and contracts with Federal, State, and local agencies, research
institutions, and industrial organizations.
Water Pollution Control Research Reports will be distributed
to requesters as supplies permit. Requests should be sent to
the Planning and Resources Office, Office of Research and
Development, Federal Water Quality Administration, Department
of the Interior, Washington, D.C. 20242.
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INVESTIGATION OF THE USE OF HIGH PURITY OXYGEN AERATION
IN THE CONVENTIONAL ACTIVATED SLUDGE PROCESS
by
Mr. J- G. Albertsson
Dr. J. R. McWhirter
Dr. E. K. Robinson
Mr. N. P. Vahldieck
Union Carbide Corporation
Linde Division
Tonawanda, New York
for the
FEDERAL WATER QUALITY ADMINISTRATION
DEPARTMENT OF THE INTERIOR
Program No. 17050 DNW
Contract No. 14-12-465
FWQA Project Officer, R. C. Brenner
Advanced Waste Treatment Research Laboratory
Cincinnati, Ohio
MAY, 1970
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FWQA REVIEW NOTICE
This report has been reviewed by the Federal Water Quality
Administration and approved for publication. Approval
does not signify that the contents necessarily reflect
the views and policies of the Federal Water Quality Admin-
istration, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
ii
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ABSTRACT
A full scale system designed to demonstrate the practical and
economical use of high purity oxygen gas in aeration of the conventional
activated sludge waste treatment process has been tested under a variety
of operating conditions in a direct performance comparison with a parallel
air aerated system. A sparged-turbine, gas-liquid contacting unit was
employed in covered tanks of conventional design with discreet liquid
and gas staging for cocurrent flow of each phase. This oxygenation
system required very low power input for oxygen transfer and liquid
mixing (0.08 - 0.140 HP/1000 gal. mixed-liquor) to routinely operate
at dissolved oxygen concentrations of 8-10 mg/1 while achieving > 90%
utilization of feed oxygen gas. It was shown that the oxygenation
system could operate with MLVSS concentrations of as high as 4500 mg/1
achieving about 90% BOD removals at aeration detention times as low as
1.2 hours (raw flow + recycle flow) treating domestic waste of 220 mg/1
BOD. Under other conditions and in direct comparison with air aeration,
the oxygenation system consistently exhibited treatment performance
superior to that achieved with air aeration even at uneconomically high
aeration rates (3-5 cf air/gal, waste treated). Biomass from the
oxygenation system is highly flocculent and readily settleable with
desirable handling characteristics. Recycle and waste activated sludge
suspended solids concentrations of about 3% were achieved.
Process advantages recognized with the oxygenation system indicate
significant reductions in secondary waste treatment costs in comparison
to conventional diffused air aerated systems. These advantages are
principally reduced aeration tank volume requirements for equivalent
treatment and a reduced production of waste activated sludge, a result
of more efficient utilization of high purity oxygen than here-to-fore
possible. As an example, the total cost of treatment, including preliminary
treatment, with air at 6 hours nominal detention time and a 1.6 cf air/
gal. aeration rate is estimated to be 15.1 cents, 13.0 cents and 11.0 cents/
1000 gal. for plant sizes of 6, 30, and 100 MGD respectively while these
costs are estimated to be reduced to 11.9 cents, 9.5 cents, and 7.8 cents/
1000 gal. for respective 6, 30 and 100 MGD plant sizes with the use of an
oxygenation treatment system capable of equivalent BOD removal at 2 hours
nominal treatment detention time.
iii
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CONTENTS
Page
TITLE PAGE i
FWQA REVIEW NOTICE ii
ABSTRACT iii
CONTENTS iv
CONCLUSIONS AND RECOMMENDATIONS vi
ACKNOWLEDGEMENTS x
BACKGROUND AND INTRODUCTION 1
Historical Aspects 1
Air Aeration Technology 3
Oxygen Aeration System Requirements 7
Linde Oxygen System Technology 8
Operation at High D.O. Levels 15
CONTRACT EXPERIMENTAL PROGRAM PLAN 18
PLANT AND EQUIPMENT DESCRIPTION 26
Plant Layout 26
Aeration Tank Modifications 28
Oxygenation Equipment 33
Aeration System Modifications 37
EVALUATION METHODS 40
Sampling Methods and Frequency 41
Methods for Individual Measurements 47
Data Reduction 54
RESULTS 55
Performance Comparison of Air & Oxygenation at Low
Treatment Rate and Low Mixed-Liquor Solids
Concentrations - Phase No. 1 Operation 55
Evaluation of an Oxygenation System at High Treatment
Rates and High Mixed-Liquor Solids Concentrations -
Phase II Operation 74
Air and Oxygenation Systems Performance Comparison at
High Treatment Rates and High Mixed-Liquor Solids
Concentrations - Phase III Operation 86
iv
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CONTENTS CONTD.
DISCUSSION
Oxygenation System Equipment Performance & Reliability 100
Overall Treatment Effectiveness 103
Determination of Yield & Endogenous Respiration
Coefficients 113
Relationship of Oxygen Utilized & BOD Consumed to
Food/Biomass Ratio & Oxygenation Detention Time 121
Relationship of BOD Removal to Detention Time and
MLVSS Concentrations 124
AIR & OXYGENATION SYSTEMS ECONOMIC COMPARISON 127
Introduction 127
Basis of Economic Comparison 128
Aeration & Oxygenation System Design 133
Primary & Waste Activated Sludge Disposal 139
Capital Constructions Costs 142
Operating & Maintenance Costs 150
Sludge Disposal Costs 155
Discussion of the Economic Comparison 155
REFERENCES 182
APPENDIX 18 3
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CONCLUSIONS AND RECOMMENDATIONS
A practical and economically attractive means for use of high
purity oxygen gas in aeration of the conventional activated sludge
process has been tested over an eight month period of continuous
operation. This work was done using a temporarily installed
oxygenation system in the existing aeration tanks at the Batavia,
New York Municipal Pollution Control Plant. A sparged-turbine, gas-
liquid contacting unit was employed for oxygen transfer. The aeration
tanks,which were of conventional design,were covered and equipped
with gas-liquid staging baffles to provide a multistage oxygenation
system. This system functioned with co-current gas and liquid flow.
The test program was specifically planned to evaluate the following:
1. The feasibility and economics of high purity oxygen use in
aeration of the conventional activated sludge waste treatment process.
2. The comparison of oxygenation and air aeration in terms of
treatment performance.
3. The consistent operation of the oxygenation system at high
mixed-liquor suspended solids (MLSS) levels (6000-8000 mg/1), high
dissolved oxygen concentrations (8-10 mg/1) and high overall utilization
of feed oxygen gas (>907<,).
4. The operation and treatment performance of an oxygenation
system at low detention times (approximately 1.2 hours based on raw
wastewater + recycle sludge flow) and high organic loading conditions
considered economically desirable but impractical with air aeration.
5. The relative economics of domestic waste treatment comparing
the cost of oxygenation with conventional (diffused air) air aeration.
The work was conducted in three phases. In two phases,the performance
of the oxygenation system was compared to a parallel air aeration system.
In a third phase, the oxygenation system was used with one-fourth of the
plant aeration tankage to treat the entire wastewater flow to the plant.
A summary of results from each of the three phases of operation is shown
in Table 1.
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TABLE 1
SUMMARY COMPARISON OF AIR AND OXYGENATION SYSTEMS PERFORMANCE
PHASE I OPERATION
PHASE II OPERATION PHASE III OPERATION
H-
H-
Wastewater Feed Rate (MGD)
Aeration Detention Time (Hrs.)*
Nominal Aeration Detention Time (Hrs.)
MLSS Concentration (mg/1)
MLVSS Concentration (mg/1)
Recycle Sludge TSS (mg/1)
Volumetric Organic Loading
Ibs. BOD/Day/1000 ft3
Mixed-Liquor Dissolved Oxygen
Concentration (mg/1)
Ft3 Air Utilized/Gal Sewage Treated
% Feed Oxygen Utilized
% BOD Removed
% COD Removed
% TSS Removed
**
AIR
1.97
3.6
4.0
2440
1740
14,960
60.0
1.5
2.89
90
76
93
OXYGEN
1.91
3.6
4.1
3060
2210
18,620
57.9
8.7
-
95.5
92
80
96
OXYGEN
2.53
1.2
1.5
6980
4450
29,560
212.5
9.0
-
92.7
90
71
89
AIR
1.29
2.6
3.0
3640
2580
16,600
128.9
0.8
4.32
-
88
79
94
OXYGEN
1.44
2.0
2.8
6190
4310
18,790
144.8
8.0
-
91.4
94
84
97
* Raw Flow + Recycle Flow
** Raw Flow Only
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The oxygenation system consistently exhibited superior treatment
performance in direct comparison to the parallel air aeration system
in spite of the fact that an unpractically high air aeration rate was
used to insure optimum performance. The power required by the oxygena-
tion unit to accomplish high treatment efficiency was only 0.08 -
0.14 HP/1000 gal. of wastewater treated.
The biomass generated by the oxygenation system was highly
flocculant and rapidly settleable, yielding sludge volume index values
as low as an average of 36. The high recycle and waste solids total
suspended solids concentration achieved (approximately 3-4% when
clarifier operation was closely controlled) obviates the requirement
for thickening of the waste activated sludge prior to further processing
for disposal.
An extensive evaluation of the oxygenation system treatment costs
in comparison to conventional air aeration reveals significant potential
savings attributable to high purity oxygen use. These savings are due
to several characteristics of the oxygenation system, but the major
factors are reduced aeration tank volume requirements for equivalent
treatment and a reduced production of waste activated sludge. As an
example, the total cost of air aeration treatment at 6 hours nominal
detention time (based on raw wastewater flow) and a 1.6 cf/gal aeration
rate is estimated to be 15.1 cents, 13.0 cents, and 11.0 cents/1000 gal
for plant sizes treating 6, 30, and 100 MGD of wastewater. For equivalent
BOD removal with oxygen aeration at 2 hour nominal detention time (based
on raw wastewater flow) these total treatment costs are estimated to be
11.9 cents, 9.5 cents, and 7.8 cents/1000 gal for the respective 6, 30,
and 100 MGD plant sizes. Total treatment costs referred to here include
investment and operating costs associated with preliminary and primary
treatment as well as the investment and operating costs associated with
secondary treatment by the activated sludge process and the disposal of
primary and waste activated sludges.
The promising results of the work reported clearly indicate the
advisability of further work to evaluate in detail certain characteristics
of the oxygenation system not yet studied in sufficient depth. Specifically,
viii
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the existing temporary installation should be used to evaluate the
following:
1. The biokinetics of the treatment process as revealed by
careful control of sludge wasting, frequent analysis of soluble BOD
and COD in feed wastewater, mixed-liquor filtrate and final clarifier
effluent.
2. Flow control should be established for the system such that
the measurements in (1) above can be made under more nearly steady
state conditions.
3. The handling properties of the waste activated sludge should
be more fully elucidated by direct vacuum filtration tests.
4. System performance should be optimized by installation and
operation of a flow proportion controlled activated sludge return
system.
5. It would be desirable to evaluate oxygen aerated, aerobic
digestion of waste activated sludge and to establish the handling
characteristics of such stablized sludge by vacuum filtration tests.
ix
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ACKNOWLEDGEMENTS
This project was conducted under the auspices of the Linde
Division's Process and Product Development Department at Tonawanda,
New York (M. L. Kasbohm - Director). The technical efforts were
a part of the Division's itestewater Treatment Technology program
and involved direct contributions by the following personnel:
J. R. McWhirter - Product Manager, New Products
F. W. Bonnet - Technology Manager
E. K. Robinson - Contract Manager
J. G. Albertsson - Supervisor
N. P. Vahldieck - Senior Engineer
R. J. Grader - Staff Engineer
D. V. Daly - Technician
J. R. Duemmer - Technician
S. E. Faruga - Technician
E. H. Kremer - Technician
P. F. Layer - Technician
Appreciation is expressed to the City of Batavia, New York
for permission to conduct the work described here at their
Municipal Pollution Control Plant. The enthusiastic attitude
displayed toward this experimental program by Ira M. Gates, City
Manager; Robert Lawrence, Superintendent of T.jater and Sewage Works
and his competent staff contributed greatly to the successful
completion of the program.
In the course of the project work, the efforts of Richard C.
Brenner, Charles L. Swanson, Robert L. Bunch, and Lawrence J.
Kamphake, of the Advanced i-Jaste Treatment Research Laboratory of
the Federal Water Quality Administration were also greatly
appreciated.
x
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BACKGROUND AND INTRODUCTION
Historical Aspects
The use of pure oxygen or oxygen enriched air in the activated
sludge waste treatment process has been the subject of a number of
technical and economic studies published over a period of more than
twenty years. Okun^ ' first reported on laboratory tests using
oxygen in a modification of the conventional activated sludge process
in 1949. This process, termed the "bio-precipitation system", was
(2)
developed from a method first suggested by Pirnie . Okun reported
the bio-precipitation process to be an effective means of treating
wastewater, at least equally efficient as present day completely
*
mixed activated sludge systems. In this process mixed-liquor is not
directly aerated, but rather the oxygen required is predissolved in
the feed wastewater to the bio-oxidation (mixed-liquor) reactor. The
bio-oxidation takes place in a gently agitated fluidized bed system
which acts as an integral reactor and clarifier. To minimize the
costly recycle of wastewater through the sludge bed to supply required
oxygen,the dissolved oxygen content of the feed stream to the reactor
was maximized using pure oxygen.
Unfortunately, the dissolved oxygen content of this stream must be
raised to a very high value and thus the effective mass transfer driving
force for oxygen dissolution into the liquid is not significantly greater
than that for conventional air aeration practice, even though a high
oxygen partial pressure aerating gas is used. This process arrangement
also is not consistent with achievement of an economically desirable
high percentage oxygen absorption and utilization necessary to minimize
oxygen production costs. Consequently, the bio-precipitation process
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has certain inherently undesirable features which tend to increase the
cost of supplying oxygen to the reactor relative to the cost of direct
aeration or oxygenation of the mixed-liquor itself.
Bud and Lambeth ' studied the bio-precipitation process in a
large pilot plant. Using pure oxygen, they reported an oxygen absorption
efficiency of 20 to 25% with an exhaust gas composition of 45-50% oxygen.
The reported power requirement, including oxygen generation, was equal
to conventional air aerated activated sludge processes. A potential
reduction in size of aeration tankage and final settler volume was
indicated as a distinct advantage for the process in terms of investment
and maintenance costs. These potential savings were based, however, on
a conservatively designed conventional activated sludge system employing
six hours aeration detention time (based on raw waste flow).
(4)
Okun and Lynn in later studies reported the sole advantage of
oxygen aeration was to reduce or eliminate the period of zero D.O.
(dissolved oxygen) yielding an apparent, but not real, increase in
effective sludge activity. They concluded that substitution of oxygen
for air or use of oxygen enriched air in standard activated sludge
aeration tanks would not be economically feasible because of poor oxygen
transfer efficiency inherent in diffuser and tank design.
Both Okun ' and McKinney ' have reviewed the "state-of-the-art" in
the use of high purity oxygen in secondary treatment and have recognized
the inherent advantage of an aerating gas with a high oxygen partial
pressure in increasing the rate of oxygen transfer. Carver has
reported data indicating that the rate of oxygen transfer with pure oxygen
aeration was essentially independent of dissolved oxygen content of the
liquid between 0 and 12 mg/1. He suggested that for systems exerting a
high oxygen demand, additional oxygen might be furnished as pure oxygen
and some air aeration might be used for providing adequate mixing only.
- 2 -
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McKinney^ ' concludes that several advantages may be achieved if
pure oxygen or oxygen enriched air could be used in the activated sludge
process. These would be the following:
1. Possibility of avoiding excessively high aeration rates
and hence obtaining a reduction in the power required per
unit of oxygen transferred.
2. Increased rate of stabilization of organic material.
3. Reduction in, or elimination of periods of zero dissolved
oxygen concentration.
4. Ability to operate high rate systems by substantial increases
in organic loading where oxygen is not limiting.
5. Reduction in plant size and thus capital investment.
6. Increased capacity of organically overloaded plants without
need for additional aerator capacity.
To this time, the major problem in realizing these potential advantages
has been the development of an efficient means of utilizing oxygen such
that a high overall utilization of gaseous oxygen, as great as 90%, might
be achieved. It has been apparent that development of satisfactory means
for effectively and efficiently utilizing high purity oxygen in the
activated sludge process was the lacking process ingredient. The absence
of this element of the technology appears as the main factor in generating
the current widespread impression that oxygen use must, of necessity, be
significantly more costly than air aeration.
Air Aeration Technology
Devices currently used in the air aeration of mixed-liquor bio-
oxidation processes can be broadly categorized in three main classes. These
are diffused air systems, submerged turbine units, and surface aeration
units. These three aeration methods span the complete spectrum of means
for supplying the necessary energy for mass transfer of oxygen from the
gas to the liquid phase and for mixing and contacting of the wastewater
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with the activated sludge biomass. On one end of the spectrum diffused
air systems supply all input energy by gas compression to generate the
interfacial area and turbulence for interphase oxygen transfer and to
accomplish adequate fluid motion in the mixed-liquor for homogenous
suspension of solids. At the opposite end of the spectrum surface
aerators supply all energy input directly to the liquid phase by mech-
anically spraying large quantities of mixed-liquor into the open atmosphere
to promote oxygen transfer in addition to bulk liquid mixing. Submerged
turbine units combine the features of the previous devices by utilizing
energy for both gas compression and mechanical fluid mixing. Although
each of these three types of aeration devices with some variations are
in general use, diffused air systems seem to predominate, especially in
municipal treatment plants using the activated sludge process.
In spite of the apparently basic differences among the three types
of air aeration devices described, the available literature indicates
that their effective oxygen transfer efficiency (as Ibs oxygen transferred/
HP hour) differs by only about 25 to 30% in normal practice. This, no
doubt, takes into account the variations introduced from procedures by
which the performance of air aeration devices are traditionally evaluated
/Q Q\
experimentally ' . A host of confusing claims and apparent anomalies
are reported in the literature which often are merely the result of
differing testing techniques, aeration conditions, and the particular
basis on which the performance is calculated and reported. Considerable
care must, therefore, be exercised in evaluating energy requirements and
costs associated with supplying oxygen to activated sludge processes
using standard air aeration techniques. These factors, however, have
little influence on the relative performance comparison of air and oxygen
aeration systems.
Oneof the generally unrecognized aspects of air aeration is the
relatively high energy requirement for dissolution of oxygen into the
aqueous mixed-liquor suspension. This is a consequence of the basic mass
transfer process which is in this instance almost entirely liquid phase
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controlled, a distinguishing feature of the dissolution of all sparingly
soluble gases in liquids. As a result, large quantities of energy are
expended in creating liquid surface and interfacial turbulence to enhance
interphase mass transfer rates. In spite of considerable effort and
technological advances made over the years, however, the gas-liquid
contacting and oxygen dissolution step remains an inherently inefficient
process in terms of the quantity of oxygen dissolved per unit of energy
input. This point is best illustrated in Table 2 wherein the energy
requirement of oxygen mass transfer in diffused air aeration is shown as
a function of the aeration conditions and mixed-liquor dissolved oxygen
level. These energy requirements, expressed as KWH/100 cf of oxygen
dissolved,are substantially greater than the cost of high purity oxygen
production (1.4 KWH/100 cf) by today's standard air separation processing
techniques. The power required, therefore, to separate oxygen from air
is considerably less than that required to dissolve oxygen from air into
mixed-liquor systems. This is the case even at zero dissolved oxygen
concentrations, an unacceptable low value for the activated sludge process
by today's standards. Therefore if the energy expended to dissolve high
purity oxygen in mixed-liquor is equal to or less than the difference
between the energy required to transfer oxygen directly from air and the
energy required to produce high purity oxygen by air separation, then
pure oxygen use may be economically competitive with air for secondary
treatment aeration.
Although standard design practice calls for mixed-liquor dissolved
oxygen concentrations of 1 to 2 mg/1, several reports in the literature
have indicated significant process performance and treatment quality
advantages in activated sludge treatment at dissolved oxygen levels of
4-5 mg/1 or in some instances greater. As Table 2 clearly illustrates,
the unfortunate situation is that the energy required, hence the cost,
of oxygen dissolution with air aeration,increases sharply with increase in
the sustained bulk liquid dissolved oxygen level. This is not unexpected
since at atmospheric pressure and 20°C the oxygen equilibrium concentration
of water with air is approximately 9.0 mg/1, equivalent to a partial
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TABLE
DIFFUSED-AIR AERATION ENERGY REQUIREMENTS AS
Liquid
Temp.
20.0
20.0
20.0
20.0
20.0
20.0
20.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
*
A FUNCTION OF
Mixed -
Liquor
D.O.
(mg/1)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Aeration conditions and
Alpha factor
Beta factor
Blower motor efficiency
Compressor efficiency
AERATION CONDITIONS*
Effective
Transfer Eff.
(Lbs. Op/HP Hr.)
1.67
1.48
1.29
1.10
.91
.72
.53
1.76
1.52
1.28
1.04
0.795
0.557
0.317
equipment efficiency
0.80
0.95
0.90
0.70
Energy
Consumption
(KWH/100 CF)
3.71
4.19
4.80
5.73
6.81
8.61
11.7
3.52
4.07
4.85
5.96
7.80
11.1
19.5
assumptions
Compressor discharge pressure - 8.1 psig
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pressure of oxygen in air of 160 mm Hg. Consequently, the energy required
(and capital investment in equipment) increases by a large factor to
increase mixed-liquor residual dissolved oxygen levels from 1.0 to 5.0
mg/1. To minimize cost of plant construction and operation, design of
aeration systems often is planned for very low dissolved oxygen levels.
It is clear, however, that treatment processes designed to operate on the
threshold of oxygen limiting conditions for the biomass may significantly
reduce the ultimate effectiveness of activated sludge treatment. In the
following, the basis for a practical and economical method of activated
sludge aeration, the use of high purity oxygen, will be contrasted to
illustrate how operation at dissolved oxygen levels of 5-10 mg/1 may be
accomplished at costs competitive with conventional air aeration at
dissolved oxygen levels of 1-2 mg/1.
Oxygen Aeration System Requirements
As pointed out in the foregoing, the potential for the use of high
purity gaseous oxygen in biological waste treatment processes, and by the
activated sludge process in particular, is a relatively well known idea.
The manner in which oxygen can be effectively and economically employed
in such processes is not, however, obvious. This statement is supported
by the fact that, in spite of more than two decades of interest in oxygen
use, no one has yet proposed (or at least reported) an effective and
economical means for doing so. Under the illustrative conditions of Table 2,
the power requirement to maintain 1.0 to 5.0 mg/1 D.O. at 20°C with air
aeration is 3.0 to 6.2 times greater than the power required for high purity
oxygen production by air separation. Therefore, oxygen use may be economically
competitive with air aeration if a means is available so that oxygen in a
relatively pure state can be efficiently (in terms of power requirement) and
effectively (in terms of high percentage absorption) dissovled in mixed-liquor.
As a first approximation, the efficiency of the dissolution process
should be higher with oxygen as the aerating gas merely as a result of the
increase in the partial pressure driving force for interphase transfer
(approximately 760 mm Hg for pure oxygen and approximately 160 mm Hg for
- 7 -
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air - a 4.75 fold increase). At the same time it is clear that high
energy utilization efficiency is not the only consideration. Simultaneously,
a high degree of oxygen dissolution and utilization is necessary.
Consequently, the problem of oxygen use is one of achieving a high per-
centage absorption while maintaining a high energy utilization efficiency for
oxygen dissolution and for mixing of the activated sludge biomass suspension.
It is well known that air aeration systems achieve only a relatively
small percentage absorption of the oxygen bubbled through or otherwise
exposed to the mixed-liquor. Diffused air systems, for example, achieve
only about a 5% absorption of the oxygen content of air while submerged
turbine units operate at 15-20% oxygen absorption efficiency. Since, as
stated previously, an oxygen aeration system must be extremely efficient
in terms of overall oxygen absorption and utilization to be competitive
with air, an analysis of conventional air aeration techniques reveals
that these approaches are not well suited to oxygen use.
Consideration of the basic requirements of an oxygen aeration system
reveals that the fundamental gas-liquid contacting problem and basic mass
transfer process must, indeed, be quite different from those of air
systems. Table 3 lists the basic requirements to be met in oxygen aeration
system design and the unique characteristics relative to air aeration. The
more important factors are high percentage oxygen absorption and energy
utilization efficiency, the small volume of gas to be contacted and the
multi-component character of the basic mass transfer process itself. These
requirements support the contention that aeration methods effective (optimal)
for air systems will not be effective or optimal for an oxygen aeration
system and vice versa.
Linde Oxygen System Technology
Recognizing that cost effective activated sludge oxygen aeration
systems must by definition differ from conventional air systems in the
means used to transfer oxygen, research and development activities have
been conducted over a six year period at the Union Carbide Corporation's
- 8 -
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TABLE 3
BASIC REQUIREMENTS AND CHARACTERISTICS OF OXYGEN
AERATION SYSTEMS
1. Enable high percentage absorption and utilization (>90%).
2. Obtain high overall energy transfer efficiency in the dissolution
process as compared with air aeration systems.
3. Provide ample liquid mixing.
A. Maintain sludge suspension
B. Maintain uniform mixed-liquor composition
4. Simple design with low maintenance costs
5. Low capital investment.
6. Volume of gas to be contacted with the liquid is about 1/90 that
of typical diffused air aeration systems.
7. Associated with (6) above, mechanical energy input will be required
to achieve the required level of bulk fluid mixing and circulation.
8. Multi-component mass transfer process. Mass transfer of inert gases
(such as nitrogen, argon, and water vapor) and bio-oxidation reaction
products (carbon dioxide) must be taken into account.
- 9 -
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Linde Division to devise simple yet highly efficient oxygenation systems
and processes applicable and competitive in the waste treatment field.
The result of this work was the development of several oxygen aeration
techniques, systems and process concepts applicable to the activated
sludge treatment of wastewater. One such method and systems approach,
having particular merit, was demonstrated in a full scale application in
the FWJA funded contract work reported here. Patents for the oxygen-
ation system technology described in this report have been applied for by
the Linde Division of Union Carbide Corporation. This particular system
is based upon the use of a series of cocurrent gas-liquid contacting
stages to enable high overall oxygen absorption efficiency at a high
average energy transfer efficiency. Figure 1 shows a schematic diagram
of the system. A series of sparger-turbine gas-liquid contacting units
are employed. This conceptual drawing illustrates four such stages in
series, but the number of stages may vary from one application to another.
Details of the gas-liquid contacting unit design employed in the work
described here will be given in the section to follow. In such a system
as shown in Figure 1, the oxygen gas is fed into the first stage at a
pressure of only about 1-3 inches of water above ambient. Small recircu-
lating gas blowers in each stage pump the oxygen through a hollow shaft
to the rotating sparge device at a rate sufficient to maintain mixed-
liquor D.O. through oxygen mass transfer. The indicated pumping action
of the impeller located on the same shaft as the sparger promotes adequate
liquid mixing and yields relatively long residence times for the dispersed
oxygen bubbles. Gas is recirculated within a stage at a higher rate than
the rate of gas flow from one stage to another. The successive aeration
stages or chambers are connected to each other in a manner which will allow
gas to flow freely from stage to stage with only a minor pressure drop
( <1.0 inches H20) but yet sufficient to prevent gas back mixing or inter-
stage mixing of the aeration gases. This is accomplished by appropriate
sizing of the interstage gas passages. The liquid flow (mixed-liquor)
through successive stages is co-current with gas flow. Stage liquid
volumes are sized appropriately to yield desired aeration detention times
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FIGURE I
SCHEMATIC DIAGRAM OF MULTI-STAGE
OXYGENATION SYSTEM
AERATION
TANK COVER
OXYGEN
FEED GAS'
WASTE
LIQUOR^
FEED
RECYCLED
SLUDGE
GAS RECIRCULATION
COMPRESSORS
r \
\
STAGE
BAFFLE
\
\
EXHAUST
GAS
MIXED LIQUOR
"EFFLUENT TO
CLARIFIER
-------
dependent on design throughput. Each successive stage is essentially
identical to the preceding except that, as a higher portion of the oxygen
demand is met in the initial stages, the required volume of gas to be
recirculated in subsequent stages will be less to maintain the desired
dissolved oxygen level in the mixed-liquor. Effluent mixed-liquor from
the system is settled in the conventional manner and the settled activated
sludge is returned to the first stage for blending with feed raw sewage.
The entire multistage activated sludge unit is fitted with a gas tight
cover to contain the oxygen aeration gas, the only exception being a
restricted exhaust gas line from the final stage. Gas is fed to the
system on demand (a small positive pressure being maintained by a flow
controller to overcome pressure drop through the unit) with the entire
unit operating in effect as a respirometer. As the organic load and
respiration (oxygen demand) of the biomass increases,the pressure tends
to decrease and feed oxygen flow into the system increases to re-establish
a pressure set point of the controller. Feed oxygen to the multistage
system can be controlled on this demand basis by a simple regulator or
differential pressure controller - automatic valve combination. The
overall power required for liquid mixing and gas recirculation will vary
with specific system configurations, but in virtually all cases will lie
between the limits of 0.08 and 0.16 HP/1000 gal. of mixed-liquor under
aeration. On the same energy requirement basis as shown for air aeration
in Table 2, this power input corresponds to about 1.2 KWH/100 cf
of oxygen transferred. The total power required to generate and dissolve
100 cf of oxygen would be about 2.6 KWH in most cases (1.4 KWH is
required to generate 100 cf of high purity oxygen from air). As may be
noted by comparison of these oxygen system power requirements with those
for air aeration in Table 2, substantially less power is required to
separate oxygen from air and dissolve it in the mixed-liquor than to
dissolve oxygen from air directly.
In general the net flow rate of gas from stage to stage is largely
determined by the net rate of oxygen mass transfer to the liquid in each
- 12 -
-------
stage. Since the rate of oxygen transfer to the liquid is usually higher
than the desorption rate of nitrogen and carbon dioxide from the mixed-
liquor, the gas flow rate will usually decrease from stage to stage.
Concurrently, however, the oxygen partial pressure of the gas phase in
successive stages will gradually decrease as the C02 and nitrogen content
increases. Normally the system will operate best with a gas composition
in the final stage of about 50% oxygen, corresponding to a 90-95% overall
oxygen absorption efficiency. Such efficiency is well within the range
of economic usage. The overall percentage oxygen absorption and average
oxygen transfer efficiency for the multistage system is determined by
the feed gas rate, number of stages, and gas-liquid contacting effective-
ness of the aerator or aerator energy input per stage.
It is necessary to vent gas from the final stage or the inert gas
concentration buildup throughout the successive stages would rapidly
reach levels unacceptable for efficient oxygen transfer. The rate of
venting will, in addition, depend upon the rate of oxygen feed, thus
upon the set point of the feed oxygen controller. Due to a net dissolution of
oxygen, the vent gas rate will be only a small fraction, e.g. about 10-20%
of the oxygen feed rate.
In spite of the dependency of overall efficiency of oxygen transfer
on the number of successive system stages, it is a consequence of
system parameters that a relatively small number of stages can achieve a
high level of performance. As an example of this consideration, one may
compare the average energy transfer efficiency of multistage systems for
equal total horsepower at a constant feed oxygen rate. The result of
this comparison indicates that a single stage system would require twice
the power of a six stage unit to achieve a 9070 oxygen utilization efficiency.
This is one of the most significant economic implications of the described
multistage aeration system; high overall oxygen absorption efficiencies
at economically attractive power input levels.
- 13 -
-------
One underlying reason for the increased performance capability of
multistage systems is, that for a given level of oxygen absorption or
total power input, the oxygen transfer is occurring at an average
partial pressure driving force which is higher than that obtainable in
a single stage unit. A single stage contacting chamber wherein the
gas phase is completely mixed cannot operate at both a commensurately
high percentage absorption and a high oxygen partial pressure. One
must necessarily be obtained at the expense of the other. The same
general compromise, of course, also applies to multistage systems, but
considerably higher overall average performance levels can be achieved.
A very desirable feature of a multistage contacting system is that it
lends itself very well to simultaneous staging of the mixed-liquor as well.
The potential benefit of a liquid staged reaction system to improve
treatment quality per unit volume of mixed-liquor under aeration has been
reported by many investigators. Pipes et al 'have evaluated staging
effects both theoretically and experimentally. Only a relatively small
number of stages gives reasonably good results in relation to an ideal
infinite stage or plug flow system.
It is well known that in a plug flow or multiple liquid stage
activated sludge system, the oxygen demand varies considerably from the
feed end to the effluent end of the system. Staging increases the oxygen
demand at the liquid feed end of the unit, compared to a completely mixed
system. Others have found that an oxygen deficit exists at the influent
end of the plug flow tanks for diffused air systems. The oxygen transfer
capacity of a multistage cocurrent oxygen aeration system, however,
naturally varies from stage to stage with the transfer rate decreasing
from the feed stage to the final or exhaust gas stage, as a result of
decreased gas phase oxygen composition. Thus, the use of cocurrent gas
and wastewater flow through a multistage contacting system tends to match
the natural oxygen demand requirement variation of the mixed-liquor with
the oxygen transfer capactiy variation of the gas contacting system. Of
course, the individual transfer capacity per stage can also be further
- 14 -
-------
varied in design by changing the energy input per stage and the oxygen
gas feed rate to the entire system.
Another very important aspect of oxygen aeration compared to air
aeration is that the oxygen transfer capacity is considerably higher
per unit of energy input. As discussed previously, this is a necessary
requirement from economic considerations, but it also has important
process performance implications. This means that the bulk liquid
agitation and mixing rate can be controlled at lower levels while
simultaneously obtaining higher D.O. concentrations. This is believed
to be a very important characteristic required for the growth of a
highly flocculant, readily settleable sludge mass particularly at high
solids loadings. Thus, with oxygen aeration, the agitation rate can
be controlled over wide ranges and at lower bulk liquid turbulence and
shear levels to promote the growth of large floe particles and a. readily
settleable biomass. The micro-organisms will still function very
efficiently in this state, however, because of the high bulk liquid D.O.
levels (5-10 mg/1) which are economically attainable with oxygen aeration.
The use of multistage oxygen aeration also lends itself quite readily
to conversion of existing air aeration systems (diffused-air rectangular
aeration tanks). This has particularly important economic implications
for the conversion of existing overloaded air aeration systems to oxygen
use, and thus enable both increased capacity and treatment quality
improvement.
Operation at High D.O. Levels
As stated previously, one of the most important advantages of oxygen
aeration is the capability for economical operation at high D.O. levels
compared to those which can practically be obtained for comparable or
considerably higher cost with air aeration. An increase in the D. 0.
level from 2.0 to 8.0 mg/1 results in a very small decrease (< 5%) in the
energy transfer efficiency and in the overall percentage oxygen absorption
for reasonable operating conditions. The performance data to be presented
here shows that economical performance levels can be obtained at D.O.
levels at least as high as 10.0 mg/1.
- 15 -
-------
The cost penalty associated with a change in oxygenation system
D.O. levels from 2.0 to 8.0 mg/1 is quite small representing only a small
percentage change in the mass transfer driving force. Quite the opposite
is, of course, true for air aeration systems wherein a change in D.O.
level from 2.0 to 5.0 mg/1 represents about a 50 percent reduction in
the available driving force for mass transfer. Table 2 indicates that
this change in D.O. level would more than double the dissolution energy
requirements for diffused-air systems as well as substantially increase
the required capital investment. Information presented here will show
that such is not the case for multistage oxygen aeration systems. Thus,
it will be seen that with oxygen aeration, practical operation of the
activated sludge process at high D.O. levels can be realized at costs
which are economically competitive with air aeration at low D.O. levels.
As stated earlier, this study has concluded that operation under these
conditions can result in substantial treatment quality improvements as
well as significant plant size reductions by enabling operation of high
solids, high rate activated sludge systems.
The conclusions from the foregoing is that a multistage oxygen
aeration activated sludge treatment system might be operated at controlled
D.O. of 8 mg/1, for example, by varying feed oxygen input or the energy
input into oxygen mass transfer regardless of organic loading variation
where appropriately designed aerators are installed to meet peak oxygen
demand of a. given treatment system. Simple feed back control systems are
possible where power input (volume of gas recirculated) might be varied
to meet organic load. In some domestic treatment facilities,low power
inputs may suffice at night with higher values for day loadings such that
power conservation is possible while D.O. remains constant throughout
the mixed-liquor at all times. It is important to note, however, that
a major advantage of the oxygenation system described here is the ability
to operate at high D.O. concentrations using only gas space pressure
control as the basis for meeting oxygen demand rather than less reliable
D.O. level control. The pressure control system is highly reliable and
provides nearly instantaneous response to changes in oxygen demand as
- 16 -
-------
may result from hydraulic or organic load variations. A D.O. level
control system may be used as a secondary means of control, but should
be regarded as a non-essential option in most cases.
The described ability to operate at high D.O. without oxygen
limitation permits a multistage oxygen aeration system to operate at high
MLVSS levels (4000-5000 mg/1 routinely). From a system kinetics point
of view, one benefit is that high overall organic removal efficiency is
possible at very low treatment detention times not possible with air.
It is not practically feasible in conventional (normal organic loading)
practice to operate an air aerated unit at MLVSS concentrations in excess
of 2500-3000 mg/1 at D.O. levels where oxygen limitation is not acute
(approximately 1.0 mg/1). Impractically high aeration rates and power
consumption would be necessary. A highly flocculant biomass enables
the achievement of such MLVSS levels in the oxygenation systems at low
sludge recycle ratios.
With the foregoing considerations in mind, the multistage oxygen
aeration system described herein was developed and tested at the pilot
scale. Results of these tests supported the contentions set forth here.
As a result the Federal Water Quality Administration of the United
States Department of the Interior funded an experimental program designed
to test the oxygen system in a full scale domestic waste treatment plant
under a variety of operating conditions. In this manner , data were
obtained by direct comparison with the performance of a parallel convent-
ional air aeration system to examine feasibility of oxygen use, overall
treatment performance, and the overall economic value of the described
system. The results of this work and conclusions evolved from these
results are the subject of this final report for the project.
- 17 -
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CONTRACT PROGRAM PLAN
The experimental program described in the following was undertaken
to directly compare the relative process and economic performance of air
and direct oxygen aeration in the conventional activated sludge process
treating typical municipal sewage under practical operating conditions.
The project was carried out at an existing municipal treatment plant
enabling direct side by side comparison of the two aeration processes
*
operating on the same feed wastewater under controlled aeration conditions
in each case. The specific program objectives were the following:
1. Demonstration of a practical and economically attractive high purity
oxygen gas-liquid contacting system for oxygenation of activated
sludge mixed-liquor in biological treatment of raw wastewater.
2. Comparison of process treatment effectiveness and economics of an
air aerated system operating at nominal dissolved oxygen levels
(1.0-2.0 mg/1) with an oxygenation system operating at high
dissolved oxygen concentrations (7-10 mg/1) under approximately
normal organic loadings and conservative aeration detention times
(approximately 5-6 hours mixed-liquor aeration detention time
(based on raw flow only) and MLVSS concentrations of 1500-3000 mg/1).
3. Evaluation of the treatment effectiveness and overall process perform-
ance of an oxygen aeration system operating at high dissolved oxygen
concentrations (7-10 mg/1), high organic loadings (up to 300 Ibs
BOD/1000 cu ft of mixed-liquor), high MLVSS concentration (4000-5000
mg/1) and very low aeration detention times (1.0-1.5 hours based on
raw sevage flow only).
4. Comparison of process treatment effectiveness and economics of an
air aeration system operating at relatively high organic loadings,
high MLVSS concentrations (2500-3000 mg/1), high aeration rates
- 18 -
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(approximately 3.0-3.5 cf/gal. sewage treated) and treatment
detention times of 2.5-3.0 hours (based on raw flow only) with an
oxygen aerated system operating at equivalent organic loadings
and detention times at MLVSS concentrations of 4000-5000 mg/1 and
dissolved oxygen concentration controlled at 7-10 mg/1.
The direct comparisons described were possible by simultaneous
operation of identical dual train activated sludge systems having completely
separate aeration tanks, clarifiers, and sludge return pumps. These
studies were conducted using the Batavia, New York Municipal Treatment
Plant with the full cooperation and consent of the local city officials
and their very capable treatment plant staff. The existing Batavia
treatment facility was completed in 1966 and designed for an average
daily flow of 2.5 MGD at an average raw sewage BOD of 225 mg/1. As data
presented here will illustrate,the average yearly flow is now in excess
of 3.0 MGD with flow variations from 1.0-6.0+ MGD. The BOD strength of
the incoming wastewater may vary from 100 to 400 mg/1. The wastewater
contains a representative mixture of domestic sewage and industrial waste.
The wastewater flow was split equally between the air and oxygen aeration
systems in comparative cases. A schematic diagram of the Batavia plant
is shown in Figure 2. The plant has no primary treatment. Unsettled
sewage is treated directly in the aeration system which is designed for
contact stabilization operation as well as conventional activated sludge
treatment.
The project consisted of four principal phases including the
installation of a temporary multistage oxygen aeration system followed
by three testing and evaluation phases of operation. The overall operation
plan is shown in Figure 3. In the first mode of operation, designated
Phase I, all four aeration bays were utilized. Two bays were aerated
with air and two with oxygen in a six stage gas contacting system. A
schematic diagram of this mode of operation is shown in Figure 4 with
indicated average raw sewage flows to each aeration train. In Phase II
of operation, the air aeration system was taken out of service along with
- 19 -
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WATER POLLUTION CONTROL PLANT, CITY OF BATAVIA.N.Y.
SCHEMATIC FLOW DIAGRAM
SLUDGE
DIGESTER
No. 2
FIGURE 2
fo DIGESTED
0 SLUDGE
SLUDGE
DISPOSAL
4r
THICKENER OVERFLOW
PLANT
EFFLUENT
CHLORINE
CONTACT
TANKS
CLARIFIER No. 2
L-. J
THICKENED
SLUDGE
SLUDGE
VACUUM FILTER
CONVEYOR BELT
DUMP
TRUCK
KEY
SEWAGE FLOW
SLUDGE FLOW
DESIGN POPULATION 25,000
AVG FLOW: 2.5 MIL. GAL./DAY
MAX.FLOW: 6.25 MIL. GAL./DAY
c r-' *••- n
i [.Til
.J !.__.
AERATION TANK No. I
AIR SYSTEM
•• • • • <
T
MIXED
LIQUOR
•••••••«••
AERATION TANK No. 2
Og SYSTEM
02
STORAGE
THIS FLOW SHEET ILLUSTRATES THE WASTE TREATMENT PLANT AT
BATAVIA. NEW YORK. BECAUSE THIS IS A DUAL-TRAIN SYSTEM.
ACCURATE COMPARISONS BETWEEN AIR AERATION AND THE
OXYGENATION SYSTEM ARE POSSIBLE USING THE SAME WASTE
WATER. THE PART OF THE PLANT OUTLINED IN HEAVY LINES HAS
BEEN ADAPTED FOR OXYGEN USE.
-------
FIGURE 3
PROJECT OPERATION PLAN
PROJECT MONTH
AIR SYSTEM
Normal
1
2
Operation
3
4
5
Diffusers and Instru
entation installed,
Piping modifications
made, Bulkhead
door
installed.
6
7
8
i- u, Phase
60
s3
CO
c
o o)
•rl 4J
4-1 CO
(0 E
4-1 CO
to e
M -H
QJ r— <
cx u
o o
1
9
1
10
11 12 13
1 Phase
•° 1
to
OJ '
j> 1
o t
o
8 '
n) i
4J '
W ,
1
II
1
Phase I
1C
111 .2
(U
C M
to •-<
r T (rt
(J w
'g o
D 4J
.to
ft
t
14 15
Final
Report
Preparatioi
-------
OXYGEN SYSTEM
AIR SYSTEM
I
1
1
.
r"
i
i
i
i
i
i
f
i
i
i
i
i
i
1.91 M6D
3.88 MGD
FEED
A
i
1.97 MGDJ
" -^
OXYGEN
SYSTEM
WATER
EFFLUENT
FIGURE 4
EFFLUENT
BATAViA TREATMENT SYSTEM
PHASE*! OPERATION
- 22 -
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one bay or three stages of the oxygen aeration system. The remaining
three stage oxygen aeration system using 1/4 of the available aeration
tankage was then used to treat the entire raw sewage flow. This system
configuration is shown diagramatically in Figure 5. In the final
evaluation, Phase III, one bay each of the air and oxygen systems were
used to treat approximately equivalent raw sewage flows. The resulting
comparison was that of a three stage gas-liquid oxygen contacting system
with a conventional high rate air aerated activated sludge system. This
configuration shown in Figure 6 indicates the addition of liquid staging
baffles to the air system. This staging baffle addition was done to
permit identical staging of mixed-liquor for both the air and oxygen
systems. Under these conditions any dissimilarities in the performance
of the two systems attributable to liquid staging were eliminated.
- 23 -
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OXYGEN SYSTEM
AIR SYSTEM
f
2.53 M60
FEED
WASTE
WATER
r
NOT
IN
SERVICE
NOT
IN
SERVICE
NOT
IN
SERVICE
EFFLUENT
EFFLUENT
FIGURE 5
BATAVIA TREATMENT SYSTEM
PHASE*2 OPERATION
- 24 -
-------
MGD
FEED WASTE WATER
OXYGEN SYSTEM
OXYGEN
SYSTEM
EFFLUENT
AIR SYSTEM
1.44 M
GO
1
i
1
I
i
1
1
1
1
1
I
1
i
-
r
}
F
NOT
W\J l
IN
SERVICE
— ^^
1
l
1
1
1
1
1
1
l
1
1
1
1.29
f
>
f
*~- —
MGD
NOT
V\ Vx 1
IN
SERVICE
^\
FIGURE 6
EFFLUENT
BATAVIA TREATMENT SYSTEM
PHASE*3 OPERATION
- 25 -
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PLANT AND EQUIPMENT DESCRIPTION
Plant Layout
The plant description for purposes of this report will be confined
to the aeration and/or oxygenation facilities in the activated sludge
secondary treatment process.
The water pollution control plant at Batavia, New York uses the
diffused air aerated activated sludge treatment process for pollutant
removal. The plant is designed for a 2.5 MGD average daily flow and a
maximum flow of 6.25 MGD. Raw sewage from the Batavia collection system
enters a pump station located remotely from the treatment plant. Grit
and debris are removed from the sewage before it is pumped through a
14-inch force main into two parallel coraminutors located at the treat-
ment plant. (Point 1 on Figure 7). From the comminutors the sewage
flows by gravity through a 30 inch diameter main to the aeration tanks.
As seen in Figure 7, four aeration tanks are used and connected hydraulic-
ally to form two parallel treatment systems. The piping of the aeration
tanks is such that both conventional activated sludge or contact stabil-
ization treatment processes can be employed by directing raw sewage
through pipe branch B or C respectively. The volume of each aeration
train (two tanks) is 325,200 gallons resulting in 6.2 hours of mixed-
liquor detention time based on 2.5 MGD feed flow. Each tank is 23 ft.
wide and 64 ft. in length.
The circular final settlers are designed for an overflow rate of
2
1000 gal/ft /day at 2.5 MSD- Settled activated sludge is pumped from the
settlers by two 6-inch diameter air lift pumps .(2) to a sink (3) from
- 26 -
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FIGURE 7
BRANCH B
BRANCH C
©
CHLORINE
CONTACT
TANKS
^->,
t
1
t 1
\^
\
^
AERATIC
u®
TANK 1
v
Tl-
,
^
i ^^
^s\
{
N TRAIN 1
(i?
*/
)
'TANK 2
*
1
t
1
1 — 1 '
1
1
1 1
1 :H —
* r
AERATJON
STAGE 1
©^
STAGE 2
L«
TANK 3
X
STAGE 3
J
^
TRAIN 2
STAGE 6
STAGE 5
~Jfo
/*iZ/
[STANK4
Is
STAGE 4
- 27 -
-------
which the return activated sludge flows by gravity to the feed end of the
aeration trains. Waste activated sludge also flows by gravity from sink
(3) to the sludge thickener. Return sludge pumping rates for each settler
can be independently controlled to meet process conditions at any given
time. Piping of the final settlers is such that both may operate with the
same or separate aeration tanks, a feature necessary for parallel process
evaluation. The final treatment step at Batavia is chlorination of the
effluent before it is discharged into Tonawanda Creek (4).
The aeration rate at Batavia is normally 1.83 cubic feet of air per
gallon of sewage treated at design flow. Air injection is accomplished
through knee joint, swing arm diffuser assemblies employing Chicago Pump,
Inc. flat disk, coarse bubble diffuser heads as gas injection units.
A number of modifications to the treatment plant were necessary to adapt
to a separate but parallel simultaneous operation of two different treat-
ment processes. Furthermore, it was necessary to build in flexibility
beyond normal treatment plant capability to successfully meet the process
parameters specified in the various phases of operation described in the
Experimental Program Plan.
Aeration Tank Modifications
The multistage high purity oxygenation process used in this study
requires that the aeration tanks be enclosed by a gas tight cover.
Also, both gas and activated sludge mixed-liquor are cocurrently staged.
These conditions can be met readily during new aeration tank construction
in which both staging baffles and cover may be made an integral structural
part of the tanks. At Batavia, however, the tanks were existing ones and
the conversion was a temporary measure designed for ease of installation
and final removal upon completion of the contract work. For this reason,
steel rather than concrete was chosen as the material for baffles and
covers. A total of six steel I-beam columns were used for structural
support of each of the two staging baffles placed in each tank. These
»
Mention of a proprietary device does not imply
endorsement by the Federal Water Quality Admin-
istration.
- 28 -
-------
columns were spaced at 38 inch center distances to form a skeleton
across the tank. Each column was anchored to the tank bottom by concrete
anchors and bolted to angles traversing the tank at the top. Liquid and
gas staging was achieved by gasketing and bolting 1/8" thick steel sheets
to the support columns. The gas seal between the tank walls and the steel
baffle was achieved by contour fitting and gasketing a flanged steel sheet
against the concrete walls. The gasketing used was an oxygen compatible
material. The gasketed flange was held against the concrete wall by
anchors spaced 6 inches apart. Two openings shown in Figure 8 for inter-
stage liquid flow were located on the tank bottom. Each of these open-
ings is 38 inches high by 34 inches wide. The size of these openings was
sufficient to pass liquid from stage to stage under low hydraulic head
while small enough so that each stage could be considered fully separated
from the next relative to mixing and oxygenation.
The cover structure for the oxygenation system was designed for two
main functions, to contain the oxygenation gas over the mixed-liquor at
a pressure not exceeding 12 inches of water column and to support the
mixing and gas recirculation equipment. Structurally the cover was
supported by two I-beams (Figure 8) spanning the tank. Each beam in
turn was supported by two pipe columns anchored to the tank bottom. The
I-beam elevation was such that its upper flange was flush with the concrete
wall tops allowing for smooth transition of cover steel from the I-beam
over the concrete. Pre-fabricated and reinforced 1/8 inch thick steel
sheets were used for cover material, each sheet spanning the tank and
overlapping the concrete. A gas tight seal between the concrete walls
and the steel covers was maintained by an oxygen compatible gasketing
material. Each cover sheet was compressed against the gaskets by bolted
down clips along all edges of the cover sheet. Access to the oxygenation
stages was provided by a 20-inch diameter manway located in each cover.
The manway covers served as safety relief gas vents in the event of over-
pressurization of the system. Relief settings of eight inches of water
column gauge pressure were maintained by appropriate water filled seals
in each manway cover.
- 29 -
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FIGURE 8
VALVE CONTROL
OXYGEN SUPPLY
17'3
-------
Sample ports (Item 17, Figure 8) for mixed-liquor sample withdrawal
were provided in each stage. These sample ports extended two feet into
the liquor to prevent gas loss during sampling. Interstage flow of oxygen
gas was through a 3-inch diameter tube located above the tank cover.
Normally interstage transfer of oxygen would be through a small opening
across the gas staging baffles beneath the tank covers, but because of
the need for gas stream monitoring this stream was exteriorized for con-
•
venience. An overall view of the cover and equipment layout is shown in
Figure 9. The air aeration tanks are shown in the foreground with the
six stage oxygenation unit in the background.
The need for complete separation and independent control of the two
parallel processes required a number of piping changes, along with the
addition of liquid flow and air flow metering stations at various loca-
tions within the plant. As pointed out earlier, the Batavia plant is
piped to operate with the conventional activated sludge or contact
stabilization process. In either case,raw feed to the aeration tanks
is measured by one Fisher porter magnetic flow meter (5)(8) located in
each feed line branch (B) and (C) (Figure 7). Installation of a second
Fisher Porter 14-inch diameter magnetic flow meter (7) was made down
stream of the flow splitting tee (9). Totalized flow to each process
was then computed from differences on the integrator totalizers for
each metering station. It was desirable to completely separate the
feed piping to each process, however, space available in the piping
tunnel and cost associated with this extensive piping modification was
prohibitive.
Return activated sludge piping in the plant did not require alter-
ations for Phase I operation, however, subsequent operational phases
required that return sludge be fed to oxygenation stage No. 4 and also
into air train aeration bay No. 2. This was accomplished by installing
(see Figure 7) 16-inch diameter sludge return pipe extensions (11) and
(12) into the aeration and oxygenation bays 1 and 3 respectively. During
Phases II and III operation, waste was fed to aeration tanks 2 and 4 only
through feed branch (C), while tanks 1 and 3 were blocked off from the
- 31 -
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FIGURE 9 OVERALL VIEW OF AIR AND OXYGENATION
SYSTEMS AT BATAVIA
i
'
i
-------
hydraulic path by installing liquid bulkheads (13)(14) in the interconnect-
ing passage between the aeration tanks. During Phase II and III operation,
return sludge was fed through pipe (11) and/or (12) into tanks 2 and/or 4
by connecting lines (11) and (12) to the liquid bulkheads (13) and (14)
shown in Figure 7.
Adequate return sludge pumping and metering capability appeared to
be available in the plant for Phase I operation. Subsequent experience
in Phase I indicated the requirement that two new 10-inch diameter air-
lift sludge return pumps be installed in lieu of the existing 6-inch
diameter air lift pumps. Also, during Phase II operation when the total
plant recycle sludge was returned to bay No. 4, it was necessary to install
a new Fisher Porter magnetic flow meter (10-inch diameter) to replace an
existing 4-inch diameter meter located at (15). No change was necessary
for the 4-inch recycle sludge meter of the air system located at (10)
for either Phase I or III operation.
Oxygenation Equipment
The multistage activated sludge oxygenation process used depends
upon separate mechanical equipment components for liquid mixing, oxygen
compression and dissolution. Both liquid mixing and oxygen dissolution
energy requirements for each stage in the system will vary considerably.
Therefore, each stage is equipped with an independent mixer-oxygenator
combination designed to provide only the required level of mixing and
oxygenation for that particular stage. This arrangement results in very
efficient oxygen transfer energy utilization through judicious matching
of efficient mixing and oxygen dissolution equipment to the requirements
of each stage throughout the multistage contacting system.
A schematic diagram of one of the contacting stages used at Batavia
is shown in Figure 8. This diagram shows an oxygenator configuration
where large fluctuations in organic and hydraulic loadings are expected,
hence an automatic dissolved oxygen level feed back control system is
used. This control, which operates by varying the gas recirculation
rate within the stage, may be provided where desirable.
- 33 -
-------
The oxygenation equipment used at Batavia was specifically custom
designed to enable efficient operation under the wide range of process
conditions evaluated in the course of the contract work. The mixer drive
(1) was a Link-Belt, shaft mounted speed reducer, (size 307D20) providing
a double gear reduction of 20:1. This speed reducer was designed to mount
directly onto a shaft to be driven with the shaft passing through the
speed reducer. This feature was necessary in order to inject oxygen gas
into the propeller shaft (4) at point (10) as shown in Figure 8.
The speed reducer was driven by a 1725 rpm electric motor (2)
through four "B" size v-belts and shieves. The output shaft (hereafter
called propeller shaft) speed, when a 1:1 shieve ratio was used, was
86.25 rpm. Propeller shaft speeds of 62.5 and 74.5 rpm were also pro-
vided through selective shieve ratios. The speed reducer (1), electric
motor (2), and propeller shaft (4) combinations were mounted on a frame
(3) designed to integrate and support the complete oxygenator assembly.
The propeller shaft (4) was a hollow carbon steel tube, 3-1/2 inches in
outside diameter with a one half inch thick wall. This shaft supported
a three bladed, 56 inch diameter marine propeller (6) suspended 126
inches below the tank cover. Since the overhanging loads at this shaft
extension became quite excessive for the speed reducer to withstand, a
steady bearing (5) was designed into the support frame and was located
approximately 20 inches below the speed reducer top bearing.
The gas injection sparger device (11) was attached to the propeller
shaft 24 inches below the propeller heel center line. The sparger device
consisted of a hollow center hub which was threaded to the propeller shaft
and from which 1-1/4 inch diameter pipes extended radially to form the
sparger arms (eight arms per assembly). Each arm as it extends outward
from the hub was swept back slightly. This swept back design was suffic-
ient to shed rags or other debris which might collect on the arms as the
sparger rotates. To minimize drag load on the arms, each arm was tapered
Mention of a proprietary device does not imply
endorsement by the Federal Water Quality Admin-
istration.
- 34 -
-------
by uniformly flattening the arm from 1-1/4 inch outside diameter at the
hub to a 1/2 inch thick, round edged, flat cross section at the tip.
Each arm was drilled through (top and bottom) with 306, 1/8 inch diameter
holes resulting in 2448 holes per sparger. Oxygen from the gas space in
each stage was fed to the sparger gas-injection unit by a positive displace-
ment, three lobe, rotary type compressor (9) through a rotary gas seal (10)
and down the propeller shaft (4). The compressor used was manufactured
*
by MGD Pneumatic, Inc. using hard coated aluminum construction for housing
and rotors. Gas leakage to the atmosphere past the rotor shafts is sealed
by high pressure carbon face seal combinations. The compressor used in
Stage No. 1 (Phase I operation) in Batavia was Model 4012 delivering
280 cfm/NTP at 1850 rpm, with 14.7 psia suction and 20.7 psia discharge
pressures. The compressor was driven by a 1750 RPM electric motor through
a 1.06:1 V-belt sheave ratio. In Phase I operation,the Stage No. 2 com-
pressor delivered 180 cfm/NTP while those on Stages No. 3, 4, 5 and 6 de-
livered 85 cfm/NTP. In Phases II and III of the operation (3 stage system
used)jthe first stage compressor delivered 180 cfm/NTP while the second
and third stage units delivered 85 cfm/NTP each.
The entire Stage No. 1 compressor output was seldom required to
maintain adequate dissolved oxygen levels in the mixed-liquor, therefore,
an automatic D.O. feedback control and control valve (12) was installed
in a bypass arrangement to regulate flow of oxygen to the sparger. The
feedback control sensing device was a Union Carbide Corporation, Model
^.
1101 dissolved oxygen probe (13) and analyzer giving a 0 to 50 millivolt
linearized output signal. This signal was transmitted to a millivolt-
ampere converter (15) having a 1 to 5 ma output (Transmatron Inc. Model
.£.
330T) . The converted signal (1-5 ma) was then used by an indicating
controller (16) (Robertshaw Controls Co. Model 321-A1-S2) with total
set point indication, manual set point, process variable and valve opening
Mention of a proprietary device does not imply
endorsement by the Federal water Quality Admin-
istration.
- 35 -
-------
indication. The 1-5 ma signal was also fed to a 2 inch pipe size auto-
matic diaphragm valve positioner. Proportional conversion of the 1-5 ma
signal to pneumatic activation of the positioner controlled the amount
of bypass gas and consequently the degree of oxygen injection to the
mixed-liquor in Stage 1. This dissolved oxygen control system, used
for the work described here, was necessary to meet the specific objectives
of the evaluation program described in the contract. In permanent installa-
tions this option would be available, using a variable speed blower, but
is not in general a necessary control system requirement for a multistage
oxygenation unit.
An item not previously described is the anti-swirl baffles (7) in
the oxygenation stages. Four baffles measuring 24 inches wide by 159
inches long were attached to the tank cover and oxygenator support columns
(8) and extended radially outward on a line drawn from the propeller shaft
and through the aerator support columns. These baffles were installed to
prevent excessive vortexing and swirl by the agitator.
The gas seal (14) around the propeller shaft was achieved by two
overlapping cups or cylinders, the lower cup being attached to the cover
plate and containing the seal water, the upper cup being attached to the
shaft and sealed to it by an "0"-ring. No operational problems were
experienced with this simple hydraulic seal arrangement.
To prevent instantaneous changes in tank liquid level, and thus
changes in pressure, a mixed-liquor effluent overflow weir was installed.
This weir served also to prevent bubble entrainment in the effluent liquor
as might occur if the mixed liquor effluent line opening were submerged.
An overall view of the oxygenation system has been shown in Figure 9,
and a close up of a single oxygenator drive, compressor and automatic
control valve arrangement is shown in Figure 10. It should be pointed
out that these gas contacting units were custom, designed to enable op-
eration under a wide variety of process conditions and were highly in-
strumented. The device in Figure 10, therefore, does not accurately
-------
reflect the type of equipment which would be employed in a permanent
installation.
Aeration System Modifications
Figure 11 shows a diagram of the air aeration piping system at the
Batavia plant. Since aeration tanks 3 and 4 were used for the oxygena-
tion system, the air header (2) valve (3) was closed and this leg of the
piping was not used. Compressed air from the three blowers was fed
through an 18-inch line to the 14-inch header (1) for diffuser banks (8)
in aeration tanks 1 and 2 as required in the various phases of operation.
The air blowers were used alternatively with the 225 HP gas engine (blower
1) usually being used during the day and the 125 HP (blower 2) electric
machine being used during the night. To increase the aeration rate
capacity in tanks 1 and 2, 100 (50% increase) additional diffusers were
added to the existing banks. Tapering of the aeration rate was accom-
plished by adjustment of the valves (4) located on each diffuser bank
swing arm header.
The amount of excess air vented to the atmosphere was regulated
manually by adjustment of the valve shown as item (5). This excess air
flow was measured by an orifice flow meter (6), the differential pressure
being recorded continuously (7). Automatic control of the air wasting
rate was established using a dissolved oxygen feed back control system
(8)(9)(10) identical to that described for the oxygenation system,
Stage 1. This was done to attempt to meet day-night changes in oxygen
demand so that a fairly constant D.O. concentration could be maintained
throughout the air aeration system mixed-liquor. In general, it was
necessary to use almost the entire air blower output to maintain the
desired D.O. concentration. As a result, only a small fraction of the
total blower output was wasted. Measurement of the blower output less
the quantity of air wasted permitted calculation of the net compression
power required to operate air tanks 1 and 2.
- 37 -
-------
FIGURE 10 VIEW OF STAGE NO. 1 OXYGENATION SYSTEM
AERATOR, BLOWER AND TURBINE DRIVE
i
-------
FIGURE II
CO
VO
|8"C.LPIPE
AERATION
TANK 9
AERATION
TANK 4
225HPOAS
ENGINE
AIR SILENCER
-------
EVALUATION METHODS
Concurrent with the installation of the oxygen aeration system at
Batavia, a combination laboratory control room and process monitoring
center was installed in the plant operation building. It was intended
that continuous recording of nearly all aspects of the systems operation
would be conducted throughout the eight month test period.
Several basic groups of information were required for performance
and economic evaluation and comparison of the air and oxygenation systems.
These were as follows:
1. Raw sewage, sludge recycle, and waste activated sludge flows for
both air and oxygenation systems.
2. Suspended and volatile suspended solids concentrations in raw
sewage, recycle sludge, mixed-liquors, and clarifier effluents
for each system.
3. Physical characteristics of the mixed-liquor as determined by sludge
volume index and initial settling velocity measurements in each
system.
4. Chemical and biochemical characteristics of the feed raw sewage,
mixed-liquor and final settler effluent in each system as revealed
by BOD, COD, ammonia nitrogen (NH3-N), nitrate nitrogen (N02-N),
nitrate nitrogen (N03-N>, total Kjeldahl nitrogen (TKN) and total
phosphorous (TP) determinations in each case.
5. Dissolved oxygen concentrations at several points in both the air
and oxygenation systems as continuously monitored and recorded.
6. Gas phase oxygen composition in the gas space of each of the stages
in the oxygenation system and in the vent gas as continuously mon-
itored and recorded.
7. Overall oxygen utilization measurement in the oxygenation system
- 40 -
-------
by measurement of feed and exhaust gas volumes and measurement
of the rate of aeration (cf air/gal, waste treated) in the air
system.
8. Measurement of actual power consumed for gas recirculation and
liquid mixing in the oxygenation system and of power required for
air compression in the air aerated system.
9. Measurement of all temperatures and pressures necessary in various
parametric calculations.
10. Measurement of gas recirculation rates within stages of the
oxygenation system.
To monitor these various groups of parameters, appropriate metering
and recording equipment was installed where possible, supplementing
the activities of on-site technicians available seven days per week to
carry out the experimental evaluation.
Sampling Methods and Frequency
Continuous composited sampling of influent raw wastewater and
final settler effluents was carried out throughout the course of the
work. These composite samples were taken for two periods of time
each day including 11:00 p.m. (previous day) to 10:00 a.m. and 10:00 a.m.
to 11:00 p.m. with the various analyses being performed individually in
each instance. These time periods were chosen to compensate for differ-
ences in day versus night organic and hydraulic loads to the plant. It
was not possible to flow proportion the composite sampling system so
that separation of the day into two sampling periods substantially
reduced inherent errors while providing the basis for additional de-
tailed information. Liquid and gas flow meter integrators were read
to correspond to the described sampling intervals. In summary data
tabulations to be reported here, night time and separate day time
values are reported for all parameters. The 24 hour mean value is the
flow weighted average of day and night operating values in each instance.
Grab samples of mixed-liquor and recycle sludge were taken for each
system three times daily and the combination of these three samples, in
each instance, was used as the composite for TSS (Total Suspended Solids)
- 41 -
-------
and VSS (Volatile Suspended Solids) analysis. Where mixed-liquor from
a multistage system was evaluated, each liquid stage was sampled by the
foregoing protocol, yielding 3 to 6 mixed-liquor solids determinations
per day, each being the combination of three grab samples.
Where SV1 or settling velocity of the mixed-liquor activated sludge
was to be measured, special grab samples were taken from each aeration
stage or tank and were immediately evaluated. Supernatant fractions of
these samples (unfiltered, settled only) were analyzed for BOD, COD, NH3-N,
NO2-N, N03-N, TP, and TKN content periodically.
When sludge wasting was done for either system (usually a 4-5 hour
period/day), special grab samples of recycle sludge were taken during
this period for VSS and TSS concentration measurement. This permitted
a more accurate estimation of the quantity of dry solids wasted from a
given aeration train. This sampling of recycle sludge during wasting,
as well as the previously described three times per day sampling, was
necessitated by occurrence of hour to hour variation in the recycle
sludge solids concentration. This condition occurred as a result of
the manual operation of recycle sludge pumps (air lifts) rather than a
more desirable flow proportioned control. Hour to hour changes in raw
sewage flow were not always compensated by manual changes in the recycle
flow rate. The resulting variation in the ratio of recycle sludge to
raw sewage flow commensurately affected changes in recycle sludge solids
concentrations. These changes were particularly evident during the
early morning hours each day when no plant operator was on duty.
At all times the oxygenation and air systems at Batavia were operated
by regular plant personnel. Linde technicians were on-site only 8 hours
per day for five days each week to conduct analysis and monitor the systems.
At all other times, weekends and evenings, off duty plant operators were
retained to collect samples, conduct certain analyses and monitor the
operation. No regular plant operating personnel or Linde technicians
were on duty from 11:00 p.m. each night to 7:00 a.m. each morning. This
was a period of unattended operation. Late night samples were taken by
off-time-operators in most cases.
- 42 -
-------
In Tables 4, 5, and 6 are shown the various analytical measurements
made for both air and oxygenation systems on feed raw waste water, mixed-
liquor, recycle sludge, and final clarifier effluent. Also indicated is
the frequency of sampling and analysis.
- 43 -
-------
TABLE 4
PHASE I OPERATION - WEEKLY SCHEDULE OF ANALYSES
Common
Feed
Analysis Wastewater
C-7
PH G-3
Turbidity
TSS C-7
1 VSS C-7
£
1 Settleability
Settling Rate & SVI
BOD tl
COD, TP , TKN, NH3-N
W),-N, and N03-N C-7
LEGEND
Mixed -Liauor
Air
Inlet
G-3
-
K-7
G-3
K-7
G-3
G-3
G-3
G-3
C
G
K
System
Middle Outlet
-
-
K-7
G-3
K-7
G-3
G-3
G-3
G-3
- Two
Day
- One
G-3
-
K-7
G-3
K-7
G-3
G-3
G-3
G-3
continuous
Periods).
grab- sample
Oxygen System
No. 1 No. 4 No. 6
G-3 G-3 G-3
...
K-7 K-7 K-7
G-3 G-3 G-3
K-7 K-7 K-7
G-3 G-3 G-3
G-3 G-3 G-3
G-3 G-3 G-3
G-3 G-3 G-3
composites daily (Night
analyzed daily.
Clarifier
Recycle Sludge Effluent
Air
Clarifier
-
-
K-7
G-7
K-7
G-7
-
-
-
"
and
Oxygen Air Oxygen
Clarifier System System
C-7 C-7
G-3 G-3
C-7 C-7
K'7 C-7 C-7
G-7 C 7 C 7
K-7
_ H — —
G-7
- . -
-
C-7 C-7
G-3 G-3
C-7 C-7
- Three grab-samples daily at equal intervals,
Number Following
Letter
(8 hours), combined and analyzed as one.
Indicates number of days each week the sample is
taken for analysis.
-------
TABLE 5
PHASE II OPERATION - WEEKLY SCHEDULE OF ANALYSIS
Ul
I
Analysis
PH
Turbidity
TSS
VSS
Settleability
Settling Rate & SVI
BOD
Feed
Wastewater
C-7
Go
-J
-
C-7
C-7
-
-
C-7
Go
-3
Mixed -Liquor
Oxygen System
Stage
G-3
K-7
G-3
K-7
G-3
G-3
G-3
1 Stage 2
G-3
K-7
G-3
K-7
G-3
G-3
G-3
Stage 3
G-3
K-7
G-3
K-7
G-3
G-3
G-3
Recycle
Sludge
_
K-7
G-7
K-7
G-7
-
_
Comb ined
Clarif ier
Effluents
C-7
G-3
C-7
C-7
-
„
C-7
G-3
COD, TP, TKN, NH3-N
NOa-N, and N03-N
C-7
G-3
G-3
G-3
C-7
LEGEND -
Number Following
Letter
C - Two continuous composites daily (Night and
Day Periods).
G - One grab-sample analyzed daily.
K - Three grab-samples daily at equal intervals
(8 hours), combined and analyzed as one.
Indicates number of days each week the sample
is taken for analysis.
-------
TABLE 6
PHASE III OPERATION - WEEKLY
Analysis
PH
Turbidity
TSS
VSS
Settleability
Settling Rate & SVI
BOD
COD, TP, TKN,
NH3-N, N02-N, and N03-N
Common
Feed
Wastewater
C-7
G-2
-
C-7
C-7
-
-
C-7
G-2
C-7
LEGEND -
SCHEDULE
Mixed -Liquor
Air
No. 1
G-2
-
K-7
G-2
K-7
G-2
G-2
G-2
G-2
C
G
K
System Stages
No.
G-2
-
K-7
G-2
K-7
G-2
G-2
G-2
G-2
2 No. 3
G-2
.
K-7
G-2
K-7
G-2
G-2
G-2
G-2
OF ANALYSES
Recycle
Oxygen System Stages Air
No.
G-2
-
K-7
G-2
K-7
G-2
G-2
G-2
G-2
1 No. 2 No. 3 Clarifier
G-2
-
K-7
G-2
K-7
G-2
G-2
G-2
G-2
Two continuous composites
Day Periods)
One grab-sample
analyzed
Three grab- samples daily
G-2
-
K-7 K-7
G-2 G-7
K-7
K-7 * '
G-7
G-2
G-2
G-2
G-2
daily (Night and
daily.
at equal intervals
Clarifier
Sludge Effluent
Oxygen Air Oxygen
Clarifier System Syster
C-7 C-7
G-2 G-2
C-7 C-7
K-7 „ , . _
G-7 C"7 C"7
K-7
t\ /
G-7
.
-
C-7 C-7
G-2 G-2
C-7 C-7
Number Following
Letter
(8 hours), combined and analyzed as one.
Indicates number of days each week the sample
is taken for analysis.
-------
Methods for Individual Measurements
1. Wastewater Feed Flow
*
Integrating Fischer-Porter magnetic flow meters were used to monitor
raw sewage flow to the air and oxygenation systems. One such meter existed
at the plant,measuring total flow to both aeration trains. A second such
meter was installed for the contract work down stream of the total flow
meter in the leg of the feed line to the air system. Meter totalizers
were read twice daily (10:00 a.m. and 11:00 p.m.) to yield "night" and
"day" average flow values. Average raw sewage flow to the oxygenation
system was obtained as the difference between total wastewater flow and
flow to the air train. Raw sewage flow rates to air and oxygen systems
were kept in balance as desired by the adjustment of relative liquid levels
in each system using effluent mixed-liquor weirs in both sets of aeration
tanks. As an example, the flow rate through the oxygenation system could
be increased by a slight increase in the height of the air system effluent
mixed-liquor overflow weir.
2. Sludge Recycle Flows
Integrating magnetic flow meters in both the air and oxygenation
system recycle sludge lines recorded the volume of sludge recycled. By
necessity,the sludge return lines for the air and oxygenation treatment
systems were completely independent permitting monitoring of each flow
independently. Flow integrator readings were taken twice daily as in
the case of raw sewage flow. In Phase II of operation,the 4 inch recycle
sludge meter in the oxygen system was replaced with a 10 inch meter to
permit operation of only one aeration bay with both clarifiers.
3. Waste Activated Sludge Flow
*
An extra Fischer-Porter magnetic flow meter was installed in add-
ition to the existing one at the plant so that sludge wasting from the
air and oxygenation systems might be independently monitored. Totalized
integrator readings were taken once daily to record the volume of sludge
wasted.
Mention of a proprietary device does not imply
endorsement by the Federal Water Quality Admin-
istration.
- 47 -
-------
4. Compressed Air Utilized
The compressed air system existing at the plant consisted of two on-
line blowers (used alternately) and a spare. The initial two blowers
supply air through a single line to air lift pumps and diffusers. Excess
air not utilized when half the plant was operated on oxygen was vented
to the atmosphere through an orifice flow meter. Revolution counters on
each blower were read twice daily (10:00 a.m. and 11:00 p.m.). The
average actual flow of compressed air for "night" and "day" periods was
calculated from the difference between total displacement at the end and
start of each period. Blower discharge pressures and temperatures were
recorded and used to convert actual compressed air flow rates to NTP
(70°F, 14.7 psia) flow rates. The pressure drop across the excess air
vent orifice was recorded as were the pressure and temperature of air
on the up-stream side of the oiifice. The vented air flow rate was
calculated using the orifice calibration constant. Air flow rates to
the air lift pumps were similarly estimated. The compressed air utilized
in aeration of the activated sludge for a given time period was calculated
from:
CAU = C - P - V
where: CAU = net compressed air utilized
C = air compressed
P = air used for lift pumps
V = vented or wasted excess air
5. Feed Oxygen Flow
A totalizing positive displacement gas flow meter in the feed oxygen
line was read twice daily (at 10:00 a.m. and 11:00 p.m.) yielding total
flow volumes corresponding to "night" and "day" periods. Averaged feed
oxygen pressures and temperatures were taken in each time period and
were used to convert feed oxygen flow from actual to NTP (70°F, 14.7
psia) conditions.
- 48 -
-------
6. Waste Oxygen Flow
A totalizing positive displacement gas flow meter in the exhaust
oxygen line from the final stage of the system was read twice daily as
indicated for feed oxygen. Waste oxygen gas pressures and temperatures
were recorded continuously. Using actual cubic feet of oxygen wasted
and average temperature and pressure of that gas, the volume was con-
verted to NTP conditions.
7. Gas Recirculation Rates
The rate of oxygen recirculation from each compressor in each stage
of the oxygenation system was measured with orifice flow meters. The
pressure drop across the orifice, up-stream gas pressure and recirculating
gas temperature were measured and recorded continuously in the "night"
and "day" time intervals. Oxygen recirculation rates were calculated
from:
1/2
W = K (Ap • d) '
where: W = weight rate of discharge
K = orifice calibration constant
Ap = pressure drop across the orifice
d = density of gas up-stream of the orifice
8. Power Required for Gas Recirculation
The power required for oxygen recirculation in each stage of the
oxygenation system was calculated from the gas recirculation rate, gas
inlet pressure and compressor discharge pressure by assuming single
stage adiabatic compression at an efficiency of 70 percent.
9. Oxygen Concentration in Feed, Exhaust, & Stagewise Recirculating Gas
Feed oxygen gas was assumed to be the purity of the temporary liquid
supply from which it was vaporized. Oxygen concentrations in the gas
space of all oxygenation system stages was continuously monitored using
•*
a multipoint Beckman Model F-3 paramagnetic oxygen analyzer having
Mention of a proprietary device does not imply
endorsement by the Federal Water Quality Admin-
istration.
- 49 -
-------
an accuracy in this range of + 1/2 percent. Exhaust gas was assumed to
have the same composition as that in the gas space of the final stage of
the system.
10. Power Required for Liquid Mixing
Power required for liquid mixing in each stage of the oxygenation
system was calculated from wattmeter readings taken several times daily
(for each mixer drive motor) using motor efficiency values provided by
the manufacturer.
11. Dissolved Oxygen Measurement
The dissolved oxygen concentration at three to five positions (de-
pending upon the number of bays in operation) in the air system mixed-
liquor, each operating stage of the oxygenation system mixed-liquor,
and in the final settler effluent from each system was monitored con-
tinuously. This was accomplished using a multipoint dissolved oxygen
monitoring system provided by the Instruments Division of Union Carbide
*
Corporation . In-place probes mounted at a liquid depth of approximately
18 inches were used in each position. The probes were calibrated in
place using a Weston and Stack Model 300E portable dissolved oxygen
*
meter having a sensing probe, submersible pump assembly, as a secondary
standard.
12. Turbidity
This measurement was made for final clarifier effluents routinely
and on mixed-liquor (settled) supernatant fractions periodically. The
.£.
instrument used was a Hach "DR" colormeter-turbidometer . The scale
calibration was in Jackson Turbidity Units (J.T.U.). Standards were
prepared as required using the hydrozine sulfate-hexamethyl tetramine
standard solution preparation.
Mention of a proprietary device does not imply
endorsement by the Federal Water Quality Admin-
istration.
- 50 -
-------
13. BOD
The method employed for BOD measurement was that described in
"Standard Methods for the Examination of Water and Wastewater". '
In all instances,three dilutions per sample were prepared and evalua-
ted. Dissolved oxygen values before and after incubation were deter-
mined using a Weston and Stack Model 300E Laboratory dissolved oxygen
•*
analyzer with the Model A-30 BOD Agitator assembly. In each instance,
the D.O. analyzer was standardized and calibrated against Winkler
titration values for replicate samples. The instrument was highly
reliable, as revealed by comparison tests run during the course of the
work, and permitted processing of significantly more samples than would
have been possible if titration had been done in each instance. All
BOD values reported here are from five day BOD determinations only.
14. Suspended Solids and Volatile Suspended Solids
These assays were performed on raw waste, mixed-liquor, recycle
sludge and final clarifier effluent routinely using essentially the
protocol outlined in "Standard Methods". The only modification
was the use of glass fiber filters (H. Reeve Angel & Company, Grade
*
934AH) instead of gooch crucibles to collect the residue. The tared
filter and residue were dried at 104°C overnight before weighing for
total suspended solids. The same tared filter and residue was then
fired at 600°C in a muffle furnace, cooled in a dessicator and weighed
to permit calculation of the volatile suspended solids by difference.
Blank glass fiber filters carried through this procedure indicated a
weight loss error of only + 0.2 mg., an error well within the sensit-
ivity range of the balance used in weighing.
15. Settleability and Settling Rate
This measurement was made using the method given in "Standard
Methods" . Thirty minute values were used for calculation of SVI
(Sludge Volume Index). Five minute interval values were recorded from
0 to 30 minutes to yield initial settling rate data.
Mention of a proprietary device does not imply
endorsement by the Federal Water Quality Admin-
istration.
- 51 -
-------
16. Mixed-Liquor Supernatant Analysis
Aliquots of mixed-liquor supernatant were withdrawn after thirty
minutes settling in the one liter cylinder to provide samples for the
various analyses to be done. For mixed-liquor supernatant (non-filtered)
this included COD, BOD, NH3-N, TKN, TP, N02-N, and N03-N. These analyses
were done to determine relative removal rates through the aeration system
stages.
17. COD Determination
The method used for COD analysis was basically that described in
"Standard Methods" . In cooperation with the analytical services group
of the FWQA Robert A.Taft Water Research Center at Cincinnati the
following modifications were made to facilitate the processing of large
groups of samples. This method was validated by analysis of known COD
standards provided by the Robert A.Taft Center Water Research Laboratory.
A 10 ml sample of raw sewage, mixed-liquor supernatant or clarifier
effluent is added to a 50 ml screw cap (Teflon cap) test tube. To this
sample is added 20 ml of the standard Ag2 S04 containing sulfuric acid
reagent with mixing. Following this, 10 ml of standardized O.lN K2Cr207
solution containing 0.25 gm of HgS04 is added with mixing. The sample
tube is securely capped and placed in an autoclave where it is digested
at a pressure of 15 psig and temperature of 120°C for a period of four
hours. After removal of the sample from the autoclave and cooling, the
sample is quantitatively transferred to a titration flask yielding a
final volume with distilled water washing of 200 ml. COD of the sample
is then determined by back titration of the K2Cr207 using O.lN Fe(NH4)2(S04)2.
The standard ferroin indicator solution is used to determine the titration
end point.
18. Total Kjeldahl Nitrogen Determination
This analysis was conducted using a Technicon Autoanalyzer. Initial
experimentation, however, indicated the necessity for predigestion of
samples containing particulate matters before use of the Technicon system.
To accomplish this, 20 ml samples of raw sewage, clarifier effluent, or
- 52 -
-------
mixed-liquor supernatant were placed in 50 ml volume screw cap tubes
(Teflon cap) and 20 ml of a 33% H2S04 solution was added to each with
mixing. The sealed sample tubes were then autoclaved at 15 psig and 120°C
for 4 hours. This predigestion step completely solubilized all particulate
material assuring the admission of a homogeneous sample to the Technicon
Autoanalyzer*.
The predigested sample was then analyzed for total Kjeldahl nitrogen
using the Technicon Autoanalysis apparatus using the method described
in Technicon Autoanalyzer Methodology, Bulletin N-3c. The only modific-
ation of the method as described was the addition of 3.5% HgCl2 solution
to the sample prior to passage through the spiral digestion tube. This
modification was suggested by the Robert A. Taft Water Research Center of
the FWQA as necessary for complete conversion of organic nitrogen to
ammonia in addition to the H2S04, Se02, and perchloric acid mixture normally
used in this digestion step of the Technicon analysis procedure. Accuracy
of the method described was verified with TKN standard solution analysis.
19. Ammonia Analysis
Analysis of wastewater samples for ammonia was done using the
Technicon Autoanalyzer. The method used was that described in Technicon
Bulletin N-3c for TKN analysis except that the digestion step was eliminated
and the sample was directly treated.
20. Total Phosphate Analysis
The method used for total phosphate analysis was essentially that
described in "Standard Methods"^ , the Aminoaptholsulfamic Acid Method
for Orthophosphate. The uniformity of the wastewater sample was assured
by digesting it at 15 psig and 120°C in an autoclave for four hours in the
presence of sulfuric acid and ammonium persulfate. Subsequent segments
of the analytical procedure were carried out using a Technicon Auto-
analyzer. This procedure essentially involved conversion of all organic-
ally bound phosphate to orthophosphate by heating the dissolved sample
at 95°C in the presence of ION sulfuric acid. The sample was then treated
* Mention of a proprietary device does not imply
endorsement by the Federal Water Quality Admin-
istration.
- 53 -
-------
with acid ammonium molybdate to form molybdophosphoric acid which yields
an intense blue color complex by the addition of a solution containing
l-amino-2-napthol-4-sulfamic acid, sodium bisulfite and sodium sulfite.
The blue color complex is developed by heating at 95°C and is measured
spectrophotometrically at 660 mo. .
21. Nitrite and Nitrate Analysis
These analysis were carried out through an automated procedure using
the Technicon Autoanalyzer. The automated method is essentially the
Diazotization Method described in the FWQA Training Manual for Laboratory
Analysis in treatment plant operation. For total nitrite analysis,
the sample is treated directly with the sulfanilic acid and a-napthylamine
to form an intense red azo dye. The color intensity was measured spectro-
photometrically at 520 m|A.
Analysis for nitrate in the sample employs the foregoing procedure
after the nitrate is reduced to nitrite by treatment with hydrazine sulfate
in an alkaline medium heated to 53°C. Nitrate nitrogen is measured as the
difference between values obtained for total nitrite alone and reduced
nitrate (nitrite plus total nitrate nitrogen).
Data Reduction
In day-to-day operation throughout the course of the work only raw
data from analysis and monitoring was collected at the work site. In
weekly batches this data was computationally reduced at Tonawanda using
an IBM 360/50 computer* and a program specifically written to analyze and
reduce the raw data to meaningful form. Technicon autoanalysis results
were dealt with in a similar manner. The product of this approach to data
reduction was a weekly average and daily listing of all system operating
conditions and performance results. The most beneficial result of this
means of data reduction was that it permitted significantly more observa-
tions and analyses to be made in the work since technicians were relieved
of devoting time to calculating and cataloging results. The quantity of
data obtained for each day of operation is so extensive that they will not
be listed on a daily basis in this report, ^eekly averages only will be
listed in the Results section.
* Mention of a proprietary device does not imply
endorsement by the Federal Water Quality Admin-
istration.
- 54 -
-------
RESULTS
Performance Comparison of Air & Oxygenation Systems at Low Treatment
Rate & Low Mixed-Liquor Solids Concentrations - Phase No. 1 Operation
The parallel operation of the air and oxygenation systems at
Batavia in the initial phase of evaluation has been shown schematically
in Figure 4. Following the completion of construction work at the
site, operation of the temporarily installed oxygen aeration system was
initiated on April 1, 1969. This system was operated separately, but
in parallel with the air aerated conventional activated sludge treatment
unit existing at the plant. The two units were completely separate
sharing equally the raw wastewater flow into the plant.
At design flow (2.5 MGD, or 1.25 MGD per aeration train) the two
aeration units should have operated at an aeration detention time
(based on raw sewage flow) of approximately 6 hours in each case
(325,200 gallon aeration tank volume per aeration train). The Spring
of 1969, however, was one of unusually heavy rainfall in Western
New York such that raw sewage inflow to the plant often was 2-3 times
design for sustained periods of time. This condition did not cause
difficulty in the aerators of either system, but did introduce
substantial problems of hydraulically overloading the final clarifiers.
Sustained overflow rates in April of 2400 gal/ft2/day or greater were
not unusual. Further, the maximum pumping capacity of the air lift
sludge return pumps was such that an average recycle sludge flow/raw
sewage inflow ratio of greater than 0.13 was not usually possible during
this period. The resulting frequent flushing of solid from the final
clarifiers severely limited the acquisition of meaningful performance
data during April. For this reason, these limited results are not
reported here.
- 55 -
-------
To improve clarifier operation, new air lift sludge return pumps
were installed in the first week of May which effectively doubled the
maximum recycle sludge capacity. This action along with a decrease in
plant hydraulic loadings during May permitted the consistent acquisition
of meaningful comparative test data in the second week of that month.
The oxygenation system had been operating for approximately six weeks
without problems at that time.
Following installation of higher sludge recycle capacity in May,
no further significant difficulties were encountered during the initial
phase of operation (through June 29, 1969). All process monitoring
instrumentation for both the air and oxygen systems functioned reliably
with only one exception, the recycle sludge magnetic flow meters. Partial
clogging of these meters with rags and other debris yielded erroneous
readings on occasion. Also the inability to properly clean the sensing
elements in these meters caused some variations in sensitivity. Both
of these difficulties probably stem from the lack of primary clarification
of raw sewage entering the aeration systems. This relatively minor
metering problem did not detract significantly from the value of the
data presented here.
The oxygenation system equipment, described earlier, functioned in
a highly reliable manner during this phase of operation. Following
start-up of the system and adjustment of feed oxygen and dissolved oxygen
controls, no further changes were necessary to operate at the predetermined
conditions. These conditions were basically treatment of one-half the
influent wastewater in a six stage oxygenation unit at a 3000-4000 mg/1
mixed-liquor suspended solids (MLSS) concentration and a mixed-liquor
dissolved oxygen concentration (D.O.) of 8-10 mg/1 with an overall oxygen
utilization efficiency of greater than 9070.
The air aeration system was operated conventionally with the
exception that the addition of 50% more diffusers in the tanks permitted
higher aeration rates than normally practiced at this plant. In general,
- 56 -
-------
the air aeration rate was controlled in the air system to provide a mixed-
liquor D.O. of approximately 2.0 mg/1 throughout the aeration tanks.
The use of manual valves on each diffuser header permitted tapering of
the aeration rate along the length of the tank. In this manner a mean
aeration rate of 3.0 ft3/gal. of sewage treated was achieved. The air
input rate at the inlet end of the aeration tank was approximately double
that of the outlet end. This yielded an almost even D.O. concentration
throughout the aeration tanks.
As noted from the operating conditions shown in Tables 7 and 8,
this initial mode of operation was a relatively conservative one compared
to existing practices at other facilities. These data reported here are
weekly averages of daily values obtained continuously on a 24 hour basis.
The combination of these seven weeks of continuous data, after six weeks
for start-up and development of characteristic biomass in each system,
provided the basis for a valid performance evaluation.
As shown in Table 7, feed wastewater flow rates were maintained at
approximately equivalent values averaging 1.97 MGD for the air system
and 1.91 MGD for the oxygenation unit for the seven week period.
Approximate control of flow through the aeration systems was accomplished
by adjustment of mixed-liquor effluent weirs installed for this purpose.
Clarifier operation was not unusual with recycle sludge to feed sewage
flow ratios in the conventional range. Recycle sludge concentrations
averaging 14,964 mg/1 and 18,620 mg/1 were observed for the air and
oxygenation units,respectively,during this operation period. Mixed-liquor
D.O. concentrations were maintained at an average of 1.5 and 8.7 mg/1
for the air and oxygen systems,respectively. In the case of the oxygen
system, D.O. control was such that a range of 8 i" 2 mg/1 was maintained
in the mixed-liquor throughout the study.
As illustrated in Table 9,a mean aeration rate of 2.89 ftVgal. of
sewage treated was maintained in the air system using a net average air
blower power input of 141 HP throughout the seven weeks. In the oxygen
system, pure oxygen was fed to the unit at an average rate of 18.3 cfm
- 57 -
-------
TABLE 7
PHASE I OPERATION - AIR AND OXYGEN SYSTEMS PERFORMANCE COMPARISON
PARAMETER PERIOD
Wastewater Feed Night
Rate in MGD Day
24 Hour Mean
Sludge Recycle Night
Rate in MGD Day
24 Hour Mean
Sludge Recycle to Night
Raw Waste Feed Day
Rate Ratio 24 Hour Mean
Wastewater Daily Average
Temp. "F
Mixed Liquor DO Night
as Average mg/1 Day
24 Hour Mean
Clarifier Effluent Night
DO in mg/1 Day
24 Hour Mean
Aeration Detention Night
Time in hours Day
(Wastewater & Recycle) 24 Hour Mean
Nominal Aeration Night
Detention Time in hours Day
(Wastewater Only) 24 Hour Mean
Raw Wastewater pH Daily Average
Mixed Liquor pH Inlet Stg. 1
Middle Stg. 4
Outlet Stg. 6
Clarifier Effluent pH Daily Average
5/12/69
AIR OXYGEN
2.03 1.57
2.20 1.88
2.12 1.74
0.31 0.61
0.26 0.60
0.28 0.61
0.15 0.42
0.12 0.34
0.14 0.38
53 53
3.5 10.5
0.4 9.4
1.9 10.1
1.7 3.9
0.4 2.2
1.0 2.9
3.3 3.6
3.2 3.1
3.3 3.3
3.8 5.0
3.5 4.2
3.7 4.5
7.5
7.6 7.4
7.2
7.6 7.1
Weekly Average of Daily Values
5/19/69
AIR OXYGEN
2.25 2.35
2.39 2.59
2.33 2.48
0.27 0.49
0.27 0.50
0.27 0.49
0.12 0.20
0.11 0.19
0.12 0.20
53 53
2.5 11.9
0.8 9.9
1.6 10.8
0.8 4.0
0.4 0.6
0.6 2.1
3.1 2.8
3.0 2.5
3.0 2.7
3.5 3.3
3.3 3.0
3.3 3.1
7.9
7.7 7.5
7.3
7.7 7.3
5/26/69
AIR OXYGEN
1.79 1.82
2.08 2.17
1.95 2.01
0.26 0.32
0.25 0.31
0.25 0.31
0.14 0.18
0.12 0.14
0.13 0.16
54 54
1.5 10.8
0.2 6.5
0.8 8.8
1.1 7.2
0.9 2.6
1.1 4.8
3.8 3.7
3.4 3.2
3.6 3.4
4.4 4.3
3.8 3.6
4.0 3.9
7.7
7.7 7.6
7.3
7.7 7.2
8.0 7.5
- 58 -
6/2/69
AIR OXYGEN
1.76 1.80
2.13 2.04
1.96 1.93
0.28 0.43
0.21 0.43
0.24 0.43
0.16 0.24
0.10 0.21
0.13 0.22
61 61
0.1 12.3
1.2 8.9
0.8 10.5
0.1 8.7
0.2 5.1
0.1 6.6
3.9 3.5
3.4 3.2
3.6 3.3
4.4 4.3
3.7 3.8
4.0 4.0
8.5
6.8 6.6
6.4
6.8 6.3
7.0
6/9/69
AIR OXYGEN
1.57 1.62
2.03 2.20
1.82 1.93
0.21 0.30
0.22 0.47
0.22 0.39
0.13 0.19
0.11 0.21
0.12 0.20
63 63
2.3 8.6
0.1 5.1
1.2 6.6
0.0 5.3
0.0 2.3
0.0 3.5
4.4 4.1
3.5 2.9
3.9 3.5
5.0 4.8
3.8 3.5
4.3 4.0
7.9
7.4 7.1
6.8
7.2 6.7
6/16/69
AIR OXYGEN
1.52 1.54
1.92 1.99
1.74 1.79
0.29
0.43
0.36
0.19
0.22
0.21
65 65
1.3 9.3
1.0 5.0
1.2 7.0
0.0 5.4
0.1 2.3
0.1 3.8
4.3
3.2
3.7
5.1 5.1
4.0 3.9
4.5 4.4
8.1
7.5 7.2
6.9
7.4 6.8
7.7 7.7
6/23/69
AIR OXYGEN
1.64 1.18
2.06 1.75
1.87 1.49
0.44
0.51
0.48
0.38
0.29
0.33
67 67
2.7 8.0
2.6 5.5
2.7 6.9
0.0 7.0
0.0 2.5
0.0 4.1
4.9
3.5
4.1
4.8 6.6
3.8 4.5
4.2 5.2
7.9 7.5
7.8 7.2
7.8 7.1
-------
TABLE 8
PHASE I OPERATION - AIR AND OXYGEN SYSTEMS PERFORMANCE COMPARISON
PARAMETER PERIOD
VSS of Feed Night
Wastewater Day
(mg/1) 24 Hour Mean
Mixed Liquor TSS 24 Hour Mean
in rag/1
Mixed Liquor VSS 24 Hour Mean
in mg/1
Recycle Sludge TSS 24 Hour Mean
in mg/1
Recycle Sludge VSS 24 Hour Mean
in mg/1
Recycle Sludge 24 Hour Mean
VSS/TSS Ratio
Sludge Volume 24 Hour Mean
Index
Initial Sludge Settl- 24 Hour Mean
ing Rate in ft/hr
Ibs. Dry Solids Each 24 Hours
Solids Wasted
Ibs. VSS Waited per 24 Hour Mean
Ib. BOD Removed
Food/Biomass Night
as Ib. BOD per Day
Ib. ML VSS 24 Hour Mean
Volumetric Organic Night
Loading as Ibs. BOD Day
per 1000 cf of 24 Hour Mean
Mixed Liquor
Effluent Turbidity Night
as J.T.U. Day
24 Hour Mean
5/12/69
AIR OXYGEN
131 131
178 178
173 173
2670 3120
1740 2200
11740 14710
7500 8520
0.64 C.59
87 60
7.0 6.4
4350 2110
1.10 0.59
0.484 0.263
0.721 0.472
0.668 0.420
46.1 32.1
74.4 63.4
60.6 47.0
5/19/69
AIR OXYGEN
68 68
154 154
118 118
2490 2940
1690 1900
13740 21000
8680 12860
0.63 0.61
84 54
8.0 9.4
2060 1100
0.74 0.35
0.213 0.197
0.627 0.602
0.500 0.408
22.9 24.4
67.9 76.2
47.5 52.2
2.3 2.2
2.5 2,6
2.4 2.8
5/26/69
AIR OXYGEN
95 95
267 267
198 198
2570 3210
1730 2220
15240 18420
10160 12000
0.65 0.66
76 55
7.8 7.1
3290 1860
0.62 0.34
0.478 0.378
0.843 0.684
0.801 0.642
53.3 51.3
91.4 100.2
82.0 90.7
2.8 4.4
3.9 4.9
3.4 4.8
- 59 -
6/2/69
AIR OXYGEN
86 86
207 207
163 163
2480 3150
1740 2178
15190 19850
9690 12260
0.64 0.62
62 59
9.2 8.1
2690 1780
0.83 0.52
0.289 0.236
0.701 0.536
0.509 0.401
31.2 31.9
75.8 73.3
55.4 54.3
9.4 4.1
7.7 6.2
8.4 4.5
6/9/69
AIR OXYGEN
79 79
167 167
130 130
2030 3500
1720 2410
14810 18600
9901 11750
0.67 0.63
60 65
9.0 6.7
2060 2470
0.73 0.73
0.264 0.194
0.647 0.468
0.473 0.356
28.5 29.4
69.9 74.7
50.9 53.9
8.0 4.4
8.2 8.2
8.1 6.7
6/16/69
AIR OXYGEN
103 103
179 179
149 149
2580 3270
1720 2540
17110 19220
11310 12660
0.66 0.66
74 70
6.8 6.3
3790 2330
1.32 0.77
0.266 0.193
0.534 0.402
0.418 0.312
31.3 32.3
60.0 63.7
48.5 51.9
7.9 8.0
7.8 13.5
7.8 11.3
6/23/69
AIR OXYGEN
184 184
130 130
136 136
2280 3250
1840 2400
16930 18540
10710 12280
0.63 0.65
91 87
6.0 6.2
3800 980
0.87 0.29
0.422 0.232
0.726 0.472
0.593 0.362
47.9 34.4
85.0 72.3
68.0 55.0
3.5 4.3
4.3 3.1
4.0 3.6
-------
PHASE I OPERATION
TABLE 9
AIR AND OXYGEN SYSTEMS PERFORMANCE COMPARISON
Weekly Averane of Daily Values
PARAMETER PERIOD
Ft Air Utilized Night
per Gallon Sewage Day
Treated (NTP) 24 Hour Mean
Air Blower Power Night
Utilized as HP Day
24 Hour Mean
Total Feed Oxygen Night
Flow Rate,CFM (NTP) Day
24 Hour Mean
Average % Oxygen 24 Hour No. 1
Composition in Mean No. 2
Gas Space of Each No. 3
Oxygen System Stage No. 4
No. 5
No. 6
Exhaust Gas Rate Night
from Oxygen Day
System 6th Stage 24 Hour Mean
cfm(NTP)
Overall 7. of Night
Feed Oxygen Day
Utilized 24 Hour Mean
Ibs. Oxygen Utilized Night
per Ib. of BOD Day
Consumed 24 Hour Mean
Oxygen Absorbed Night
as Ibs/hr Day
24 Hour Mean
5/12/69
AIR OXYGEN
2.76
2.37
2.54
138.6
128.8
133.3
15.8
16.6
16.2
92
84
80
73
64
49
2.53
2.55
2.40
93.3
92.1
92.6
1.20
0.68
0.85
73.4
75.6
74.6
5/19/69
AIR OXYGEN
2.61
2.31
2.44
145.7
136.5
140.7
13.6
16.6
15.2
90
81
77
68
57
42
2.13
2.18
2.16
93.2
94.5
94.0
1.79
0.65
0.90
63.1
77.9
71.1
5/26/69
AIR OXYGEN
3.18
2.46
2.76
141.2
126.7
133.3
16.2
18.8
17.6
91
83
80
72
62
42
1.46
1.57
1.52
96.2
96.5
96.4
0.91
0.55
0.56
77.6
90.2
84.4
- 60 -
6/2/69
AIR OXYGEN
3.04
2.42
2.67
134.6
129.8
132.0
17.1
18.5
17.9
92
86
82
76
65
46
1.40
1.40
1.40
96.2
96.5
96.4
1.63
0.74
0.96
81.9
88.9
85.7
6/9/69
AIR OXYGEN
3.93
2.93
3.33
156.0
150.7
153.1
18.1
21.3
19.9
94
87
83
78
66
48
1.48
1.52
1.50
95.8
96.6
96.2
1.84
0.81
1.05
85.6
102.4
94.3
6/16/69
AIR OXYGEN
3.84
2.84
3.24
147.8
137.4
142.2
18.9
21.6
20.3
91
85
81
75
65
47
1.58
1.46
1.52
96.1
96.8
96.5
1.76
0.95
1.18
90.3
103.6
97.5
6/23/69
AIR OXYGEN
3.93
2.76
3.23
162.9
143.6
152.5
19.5
22.3
21.0
91
85
81
76
63
45
1.61
1.49
1.54
96.3
96.9
96.7
1.61
0.88
1.09
93.3
107.3
100.9
-------
and gas was exhausted from the system at an average rate of 1.74 cfm.
This exhaust gas contained an average of 4670 oxygen. On this basis^ the
overall average oxygen utilization efficiency for the oxygenation system
during the seven week period was 95.57o. As shown in Table 10, power
required to accomplish liquid mixing and gas recirculation in the oxygen
system averaged 26.0 ji'id 2.6 HP, respectively. Individual power consumption
values for each aeration stage are listed on a weekly average basis. The
total average power input for the oxygenation system was 28.6 HP for the
operational period shown. On a unit tank volume basis,the seven week
average of those values listed in Table 10 indicates a power input for
the oxygenation unit of 0.088 HP/1000 gal. of mixed-liquor.
From the standpoint of treatment effectiveness, the results shown in
Table 11 list the influent waste strength in terms of BOD, COD, and
total suspended solids (TSS). Influent volatile suspended solids concen-
trations are noted in Table 8. Also shown in Table Hare the concentrations
of BOD, COD, and TSS in the final clarifier effluent after treatment. The
BOD and COD concentrations of the clarifier effluent were determined by
analysis of whole, not filtered, samples. Listed appropriately are
weekly average values for BOD, COD, and TSS removal throughout the seven
week period. As in most of the data presented here, night, day and 24-
hour average (flow weighted) values are listed in each instance. The
time period for night samples was pointed out earlier as 11:00 p.m. to
10:00 a.m. the following morning with day samples including continuous
composites taken from 10:00 a.m. to 11:00 p.m. This latter period
corresponds to the highest organic and hydraulic loading period of the
day.
As illustrated by examination of the data in Table 11, the waste
strength with respect to BOD was lower during this seven week period
than the normal yearly average at the plant of 200 mg/1. This, no doubt,
was due to the dilution effect of ground water infiltrating the system.
The seven week average BOD of the influent wastewater was 159 mg/1 on
a 24-hour basis. The clarifier effluents for the air and oxygenation
- 61 -
-------
TABLE 10
PHASE I OPERATION - AIR AND OXYGEN SYSTEMS PERFORMANCE COMPARISON
Weeklv
PARAMETER PERIOD
Power Required 24 Hour No. 1
for Liquid Mixing Mean No. 2
in Oxygen No. 3
System (per Stage No. 4
as HP) No. 5
No. 6
Power Required for 24 Hour No. 1
Gas Recirculatlon Mean No. 2
in Oxygen System No. 3
(per Stage as HP) No. 4
No. 5
No. 6
Overall Power Night
Required for Day
Liquid Mixing 24 Hour Mean
(as HP)
Overall Power Night
Required for Day
Gas Recirculation 24 Hour Mean
(as HP)
Overall Power Night
Utilized as HP Day
per 1000 ft3 of 24 Hour Mean
Mixed Liquor
Clarifier Overflow Night
Rates as Day
gal/ft2/day 24 Hour Mean
5/12/69
AIR OXYGEN
7.3
4.8
4.3
3.9
3.1
3.2
0.5
0.5
0.4
0.3
0.3
0.3
26.6
26.5
26.6
2.2
2.2
2.2
0.089
0.088
0.089
1616 1250
1751 1496
1687 1385
5/19/69
AIR OXYGEN
7.1
4.6
4.2
3.8
3.1
3.1
0.7
0.6
0.3
0.3
0.3
0.4
25.9
25.9
25.9
2.6
2.6
2.6
0.088
0.088
0.088
1791 1870
1902 2061
1854 1978
5/26/69
AIR OXYGEN
6.6
4.5
4.1
3.8
3.0
3.0
0.7
0.5
0.3
0.3
0.3
0.4
25.3
24.8
25.0
2.5
2.3
2.4
0.085
0.083
0.084
1425 1448
1655 1727
1552 1600
- 62 -
Averaee of Dall
6/2/69
AIR OXYGEN
7.2
4.9
4.2
3.9
3.1
3.2
0.7
0.6
0.4
0.3
0.4
0.4
26.3
26.6
26.5
2.9
2.9
2.9
0.090
0.091
0.090
1401 1433
1695 1624
1560 1536
v Values
6/9/69
AIR OXYGEN
7.0
4.8
4.1
3.8
3.1
3.2
0.8
0.5
0.3
0.3
0.3
0.3
25.5
26.4
26.0
2.4
2.4
2.4
0.086
0.087
0.087
1250 1289
1616 1751
1448 1536
6/16/69
AIR OXYGEN
7.1
4.6
3.9
3.7
3.1
3.0
0.6
0.6
0.4
0.3
0.3
0.4
25.3
25.6
25.5
2.7
2.5
2.5
0.086
0.086
0.086
1210 1226
1528 1584
1385 1425
6/23/69
AIR OXYGEN
7.2
4.9
4.2
3.8
3.1
3.2
0.8
0.6
0.4
0.3
0.4
0.5
26.1
26.6
26.4
3.0
2.9
3.0
0.089
0.091
0.090
1305 939
1640 1393
1488 1186
-------
TABU: 11
PHASE I OPERATION - AIR AND OXYGEN SYSTEMS PERFORMANCE COMPARISON
PARAMETER PERIOD
Feed Wastwater Night
BOD (mg/1) Day
24 Hour Mean
Clarifier Effluent Night
BOD (mg/1) Day
24 Hour Mean
% BOD Removed Night
Dav
v<* J
24 Hour Mean
Feed Wastewater Night
COD (mg/1) Day
24 Hour Mean
Clarifier Effluent Night
COD (mg/1) Day
24 Hour Mean
% COD Removed Night
Day
24 Hour Mean
Feed Wastewater Night
TSS (mg/1) Day
24 Hour Mean
Clarifier Effluent Night
TSS (mg/1) Day
24 Hour Mean
% TSS Removed Night
Day
24 Hour Mean
5/12/69
AIR OXYGEN
120 120
180 180
152 152
10 9
11 7
10 7
91 93
94 96
93 95
312 312
560 560
461 461
189 193
196 197
183 197
40 38
65 65
58 57
132 132
317 317
267 267
9 13
12 10
10 5
93 90
96 97
95 96
5/19/69
AIR OXYGEN
52 52
144 144
102 102
10 9
13 10
12 11
81 83
91 93
88 90
178 178
376 376
289 289
53 47
32 44
41 47
70 74
92 88
86 84
101 101
244 244
185 185
12 8
10 12
11 10
89 92
96 95
94 95
i i '
5/26/69
AIR OXYGEN
150 150
228 228
231 231
18 16
22 11
19 14
88 89
90 95
92 94
262 262
465 465
389 389
50 59
72 60
63 60
81 77
84 87
84 85
149 149
386 386
286 286
10 12
13 8
12 10
93 92
97 98
96 96
- 63 -
It Inn
AIR OXYGEN
93 93
186 186
147 147
16 13
23 17
19 14
82 86
88 91
87 90
180 180
398 398
307 307
72 48
100 47
89 45
60 73
75 88
71 85
110 110
333 333
239 239
21 8
22 18
22 14
81 93
93 95
91 94
e. lo/f.a
AIR OXYGEN
94 94
178 178
145 145
18 11
23 12
21 12
81 88
87 93
86 92
214 214
362 362
304 304
66 62
74 29
72 41
69 71
80 92
76 86
98 98
210 210
167 167
20 8
26 8
24 8
79 91
88 96
86 95
6/16/69
AIR OXYGEN
105 105
167 167
144 144
13 10
14 9
14 11
88 91
91 95
90 92
217 217
292 292
330 330
66 54
63 45
62 50
69 75
84 89
81 85
137 137
240 240
210 210
15 11
21 6
19 8
89 92
91 97
91 96
AIR OXYGEN
154 154
211 211
190 190
16 12
13 10
14 11
90 92
94 95
93 94
342 342
419 419
386 386
90 74
60 68
78 74
74 78
86 84
80 81
261 261
184 184
192 192
13 11
13 9
12 10
95 96
93 95
94 95
-------
systems contained 16 and 11 mg/1 BOD,respectively,yielding an average
overall BOD removal by the air system of approximately 907,, and a removal
of 927» by the oxygenation system. The COD concentration of influent
wastewater averaged 352 mg/1 for the seven week test period on a 24-hour
per day basis. As illustrated in Table 11, daytime COD concentrations
as high as 560 mg/1 on a weekly average basis were observed. Seven week
average COD concentrations in the effluent of the air and oxygenation
systems of 84 and 73 mg/1,respectively, were observed, indicating an average
COD removal efficiency for the test period of 807» for the oxygenation
system and 767» for the air aeration unit. TSS removals by both the
oxygenation system and air aerated activated sludge unit were quite good
as may be observed in Table 11. From a seven week average TSS concentration
of 221 mg/1 in the influent wastewater, 937o was removed in the air aeration
system and 9670 in the oxygenation system.
Table 12 indicates weekly average values for phosphorous removal
by the air and oxygenation systems. Removal of 447» for the air system
and 397o for the oxygenation system were observed on an overall seven
week average basis. These values were based on total phosphate analysis
rather than ortho-phosphate alone.
Listed in Tables 12 and 13 are weekly average results of analysis
for NH3-N, TKN, N02-N and N03-N in feed wastewater to and clarifier
effluent from both the air and oxygenation treatment systems. In viewing
these results,it should be noted that in the instance of clarifier effluents,
whole composite samples rather than filtered samples were analyzed. On
an overall seven week basis, NH3-N removal by the oxygenation system was
- 64 -
-------
TABLE 12
PHASE I OPERATION - AIR AND OXYGEN SYSTEMS PERFORMANCE COMPARISON
PARAMETER
Total Phosphate in Feed
Wastewater as
mg/1 of P
Total Phosphate in
Clarifier Effluent
as mg/1 of P
Total % Phosphate
Removed
Ammonia Nitrogen
in Feed Wastewater
as mg/1 N
Ammonia in Clarifier
Effluent as
mg/1 N
TKN of Feed
Wastewater as
mg/1 N
TKN of Clarifier
Effluent as
mg/1 N
N02 Nitrogen
in 'Feed Wastewater
as mg/1 N
N02 Nitrogen in
Clarifier Effluent
as mg/1 N
PERIOD
Feed Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
er Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
— 5/12/69
AIR OXYGEN
9 9
15 15
12 12
5 6
7 7
6 7
38 30
52 51
49 45
14 14
17 17
16 16
17 17
13 14
13 14
27 27
35 35
31 31
21 22
19 18
19 19
0.2 0.2
0.2 0.2
0.2 0.2
0.9 0.5
0.6 0.6
0.7 0.5
5/19/69
AIR OXYGEN
5 5
12 12
9 9
4 5
5 6
5 5
24 13
55 49
47 42
10 10
15 15
13 13
9 10
12 11
10 10
19 19
32 32
26 26
16 13
19 16
17 15
0.4 0.4
0.3 0.3
0.3 0.3
0.9 0.8
1.0 0.9
1.0 0.8
5/26/69
,IR OXYGEN
8 8
17 17
13 13
5 6
7 7
6 7
36 22
61 57
56 49
26 26
22 22
23 23
16 12
19 5
18 8
44 44
48 48
45 45
21 20
26 20
24 20
0.3 0.3
0.0 0.0
0.1 0.1
0.4 1.1
0.4 0.9
0.4 1.0
- 65 -
~T72/69
AIR OXYGEN
6 6
15 15
12 12
5 6
6 6
6 6
16 13
58 59
48 48
24 24
23 23
23 23
18 18
21 19
20 19
28 28
38 38
34 34
23 19
25 22
24 20
0.4 0.4
0.2 0.2
0.3 0.3
0.2 1.0
0.2 0.9
0.2 0.9
6/9/69
AIR OXYGEN
6 6
12 12
10 10
7 8
7 8
7 8
-10 -27
41 37
29 21
16 16
22 22
20 20
18 18
19 18
18 18
25 25
35 35
31 31
18 18
19 19
19 18
0.1 0.1
0.0 0.0
0.1 0.1
0.1 0.9
0.1 0.7
0.1 0.8
6/16/69
AIR OXYGEN
8 8
17 17
14 14
8 9
8 8
8 9
-1 -19
55 51
45 39
19 19
25 25
24 24
23 21
19 16
21 19
27 27
38 38
35 35
26 23
24 18
26 21
0.1 0.1
0.2 0.2
0.1 0.1
0.3 1.1
0.1 0.8
0.2 0.9
6/23/69
10 10
12 12
10 10
6 7
7 8
7 7
40 31
38 36
32 30
25 25
21 21
23 23
16 13
20 19
20 18
36 36
34 34
35 35
17 14
23 20
22 20
0.1 0.1
0.0 0.0
0.0 0.0
0.1 1.1
0.2 1.2
0.1 1.2
-------
TABLE 13
PHASE I OPERATION - AIR AND OXYGEN SYSTEMS PERFORMANCE COMPARISON
PARAMETER PERIOD
N03 Nitrogen in Night
Feed Wastewater Day
as mg/1 N 24 Hour Mean
N03 Nitrogen in Night
Clarifier Effluent Day
as mg/1 N 24 Hour Mean
Total Nitrogen Night
in Feed Wastewater Day
as mg/1 N 24 Hour Mean
Total Nitrogen in Night
Clarifier Effluent Day
as mg/1 N 24 Hour Mean
'/„ Total Nitrogen Night
Removed Day
24 Hour Mean
NOj-N/Total N Night
in Feed Wastewater Day
24 Hour Mean
NOj-N/Total N Night
in Clarifier Day
Effluent 24 Hour Mean
Lbs. Total Nitrogen
Removed per Lb. Dry
Solids Wasted 24 Hour Mean
5/12/69
AIR OXYGEN
0.8 0.8
0.4 0.4
0.6 0.6
0.8 1.2
0.4 1.0
0.5 1.1
28 28
35 35
32 32
23 24
20 20
20 21
18 14
45 43
38 35
0.03 0.03
0.02 0.02
0.02 0.02
0.04 0.06
0.02 0.05
0.03 0.06
0.049 0.075
5/19/69
AIR OXYGEN
1.3 1.3
0.5 0.5
0.8 0.8
0.9 1.9
0.6 1.7
0.7 1.8
21 21
33 33
27 27
17 16
20 18
19 17
17 24
37 44
31 36
0.06 0.06
0.02 0.02
0.04 0.04
0.06 0.14
0.04 0.09
0.05 0.11
0.075 0.188
5/26/69
0.5 0.5
0.1 0.1
0.2 0.2
0.7 1.5
0.6 0.9
0.7 1.2
45 45
48 48
46 46
22 23
27 22
25 22
50 49
44 55
46 52
0.01 0.01
0.00 0.00
0.01 0.01
0.05 0.08
0.03 0.04
0.04 0.06
0.104 0.216
- 66 -
6/2/69
0.8 0.8
0.0 0.0
0.3 0.3
1.1 2.2
0.7 1.7
0.8 2.0
29 29
39 39
35 35
24 22
26 24
25 23
18 26
33 38
28 33
0.03 0.03
0.00 0.00
0.01 0.01
0.04 0.11
0.03 0.07
0.03 0.09
0.060 0.108
6/9/69
0.1 0.1
0.1 0.1
0.1 0.1
0.9 1.4
0.8 1.0
0.8 1.1
26 26
35 35
31 31
19 20
20 20
20 20
26 22
42 41
37 35
0.00 0.00
0.00 0.00
0.00 0.00
0.05 0.07
0.04 0.05
0.04 0.06
0.081 0.072
6/16/69
AIR OXYGEN
0.1 0.1
0.1 0.1
0.1 0.1
1.0 2.1
0.7 1.3
0.9 1.5
27 27
39 39
36 36
27 26
25 21
27 23
-1 2
36 47
25 34
0.01 0.01
0.00 0.00
0.00 0.00
0.04 0.09
0.03 0.06
0.03 0.07
0.034 0.083
6/23/69
AIR OXYGEN
0.3 0.3
0.1 0.1
0.2 0.2
0. 1 3.4
0.2 2.3
0.1 2.7
36 36
35 35
36 36
17 19
23 23
22 23
53 49
34 33
37 34
0.01 0.01
0.00 0.00
0.00 0.00
0.00 0.21
0.01 0.12
0.00 0.14
0.057 0.165
-------
higher than that of the air aerated unit, a concentration of 15 mg/1 in
the clarifier effluent of the former system and 17 mg/1 in the latter.
This same comparative relationship existed for TKN, 22 mg/1 in air
system effluent and 19 mg/1 in oxygenation system effluent. It is
clear that virtually all TKN of the clarifier effluents in both cases
is constituted by NH3-N rather than organically bound nitrogen. Exam-
ination of the nitrite and nitrate nitrogen content of feed wastewater
and clarifier effluents reflect the magnitude of difference in NH3-N
and TKN removal between the two systems. The oxygenation system accomplished
some nitrification, 0.8 mg/1 N02-N and 1.6 mg/1 N03-N in the effluent,
while the air aeration system effluent contained 0.4 mg/1 N02-N and 0.6
mg/1 N03-N. Overall nitrogen removals by both systems are listed in
Table 13 on a weekly average basis. Also listed in each instance is the
N03-N/Total N ratio of feed wastewater and clarifier effluent and the
quantity of nitrogen removed in each system as a function of the quantity
of dry solids wasted.
Characteristics of the biomass from the air and oxygenation systems
are indicated in Table 8. On an average basis for the seven week period,
the MLVSS concentration of the oxygenation system was 2,266 mg/1 while
that of the air system was 1,740 mg/1. This biomass was subjected to
volumetric organic loadings on a 24-hour average of 57.9 and 60.0 Ibs.
of BOD/1000 ft3 of mixed-liquor for the oxygenation and air systems,
respectively. The corresponding food to biomass daily weight ratios
are also listed on a weekly average basis. Day to night variations in
food/biomass ratio vary by a factor of two on the overall average and
by as much as a factor of six in a given week for both systems. The
seven week average SVI of the air and oxygenation systems were 76 and 64,
respectively. The settling rate of the two activated sludges were nearly
identical on an overall average basis, even though the higher MLSS
concentration in the oxygenation system should have yielded a relatively
lower hindered settling velocity than that of the lower MLSS concentration
in the air system. Settling rates were determined using the standard one
liter graduated cylinder.
- 67 -
-------
Table 8 also lists the daily amount of dry solids wasted from each
treatment system on a weekly average basis. Remarkably, the air system
produced a daily average of 3,148 Ibs. of solids for the seven week
period while a daily average of 1804 Ibs. were wasted from the oxygen-
ation system. As indicated from the recycle sludge VSS/TSS ratio, the
wasted sludge from both systems is approximately 6570 volatile solids.
Since both aeration systems received approximately the same quantity of
common influent sewage, hence the same amount of influent TSS, VSS, BOD,
and COD, it is clear that a characteristic of the oxygenation treatment
system is the production of significantly less waste activated sludge
than the air aeration system operated in parallel with it. This is
further shown in Table 8 wherein comparative values are listed for Ibs.
of excess VSS wasted from each system per Ib. of BOD removed (an average
of 0.856 Ibs. VSS/lb. BOD in the air system and 0.482 Ibs. VSS/lb. BOD
in the oxygenation system). In this context,it is useful to note the
Ibs. of oxygen utilized in the removal of one Ib. of BOD in Table 9.
This is key to the subsequent discussion of how significant reductions
in waste sludge production are possible with oxygen aeration.
During the final week of parallel operation of the air and
oxygenation treatment systems in June, a brief period of intensive
analysis of the mixed-liquor in each system was carried out. The results
of these analyses are listed in Tables 14, 15, 16, 17, and 18. This
work included a cursory enumeration of higher biological forms, rotifers
and protozoa present in each system. As indicated, grab-samples (rather
than composites) were evaluated. All samples were taken at the times
indicated.
Included in the Appendix of this report is Table I, analyses of
mixed-liquor supernatant from each system made during six weeks of the
Phase I study. In this instance,the values result from analysis of
mixed-liquor supernatant decanted from the one liter graduated cylinder
after the thirty minute settling test.
- 68 -
-------
TABLE 14
INTENSIVE
Sample
BOD
Common Feed Waste 130
Air Train
Inlet
Middle
Exit
Oxygen Train
Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Stage 6
Effluent
44
20
19
47
23
24
22
22
20
TSS VSS
175 118
3080 1858
3250 1982
3126 1860
2960 1958
3342 2024
3166 2050
3272 2098
3512 2360
3266 2120
MIXED-LIQUOR EVALUATION
9:00 A.M. - June 24,
_ Settling^
TS TVS Turbidity
-
3732 2112
3948 2190
3918 2222
3550 2028
3802 2224
3884 2248
3920 2294
4122 2432
3962 2328
62.0
8.4
7.2
7.3
16.0
10.5
9.0
7.6
11.0
10.2
Velocity SVI
-
6.1
6.0
6.8
7.5
7.0
6 7
>J • /
6.3
5.1
5.7
-
87
86
97
85
79
85
\J J
87
87
87
1969
PH
8.76
8.00
7.87
7.82
7.65
7.47
7 42
/ • *T fc
7.24
7.20
7.07
COD P
282 6.7
105 5.4
124 5.4
141 5.1
111 6.6
93 5.5
Q? 5 fi
s £* ~J • \J
133 5.6
85 5.6
99 6.0
TKN NH3-N
43.0 29.0
26.9 21.8
22.8 18.0
19.3 17.5
34.4 23.1
26.6 20.4
?? 5 1 7 L
£.£. * J J./.H
18.0 14.5
15.0 13.0
16.8 12.4
Free Swim. Cilif
N02-N N03-N Stalked Cilia
0.3
0.0
0.0
0.0
0.5
0.6
0 7
u * /
1.0
1.4
1.4
0.1
0.0
r\ n 290/ml . „
0.0 _^___ _ = ^ ^ g
0.0
0.7
1 2
• 480/ml _
}^ 70/ml 6'9
2.0
2.3
From Air
Train Clarifier
From Oxygen
Train Clarifier
11 15
13
4.3
4.5
7.90 69 5.5 19.2 16.9 0.0
0.0
7.12 74 6.0 18.0 17.1 1.0 3.6
1 All samples were taken at the time indicated,
settling was analyzed for BOD and nutrients.
2 Units are mg./l. unless otherwise indicated
3 J.T.U. units
4 Velocity in ft/hr.
Supernatant after 30 minutes,
- 69 -
-------
15
INTENSIVE MIXED-LIQUOR EVALUATION
2:00 P.M. - June 24, 1969
Settling
Free Swim. Cilia
Sample
Common Feed Waste
Air Train
Inlet
Middle
Exit
Oxygen Train
Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Stage 6
Effluent
From Air
Train Clarifier
BOD
230
43
20
18
55
60
36
40
37
39
11
TSS VSS
216 145
2524 1482
2520 1606
2508 1608
3128 2092
3380 2276
3138 2018
2912 1954
3226 2216
-
13
TS TVS
-
3614 2334
3418 1884
3438 1962
3590 2048
3928 2318
3740 2256
3748 2142
3998 2392
3986 2444
-
Turbidity
80.5
11.5
9.8
8.9
17.7
14.2
14.1
15.0
13.2
16.9
2.8
Velocity
-
6.5
7.1
7.1
7.5
7.1
7.5
7.4
7.6
7.4
-
SVI
-
92
88
92
77
78
81
87
74
-
-
PH
-
8.13
7.87
7.81
7.67
7.49
7.41
7.23
7.24
7.20
-
COD P TKN NH3-N
480 16.5 38.0 26.0
131 8.5 31.1 25.0
100 7.7 28.0 23.1
92 7.4 26.4 22.4
121 9.5 28.5 24.0
237 9.0 28.5 20.6
134 9.5 26.9 20.2
38 9.2 21.9 20.1
117 9.0 24.8 20.5
83 8.1 26.5 20.4
127 6.0 23.0 22.5
N02-N
0.1
0.0
0.0
0.0
0.5
0.5
0.6
1.0
0.9
1.1
0.0
N03-N
0.1
0.0
0.0
0.0
0.6
0.7
0.7
1.0
0.9
0.8
0.0
Stalked Cilia
o en /ml
£.J\J/IUL _ 0 Q
— x / * ^ • O
90/ml
•11 n/ml
Jiu/nn _ _
AH /ml
oU/ml
From Oxygen
Train Clarifier
11 5
2.4
91 5.3 21.0 19.8 1.9 0.3
1 All samples were taken at the time indicated.
settling was analyzed for BOD and nutrients.
2 Units are mg./l. unless otherwise indicated.
3 J.T.U. units
4 Velocity in ft/hr.
.Supernatant after 30 minutes
- 70 -
-------
TABLE 16
INTENSIVE MIXED-LIQUOR EVALUATION
9:00 A.M. - June 25, 1969
Settling'
Free Swimming Cilia
Sample
BOD2 TSS VSS Turbidity3
Common Feed Waste 205
Air Train
Inlet
Middle
Exit
Oxygen Train
Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Stage 6
Effluent
From Air
Clarifier
From Oxygen
Clarifier
40
28
21
60
43
39
29
29
25
11
16
173 151
2620 1566
2984 1752
3070 1850
3180 2276
2588 1810
2666 1864
2924 1982
3900 2820
3650 2642
11 10
10 8
-
7.7
6.4
5.9
18.1
12.3
10.2
9.6
7.6
8.2
3.2
4.0
______ __ ^j
Velocity
-
6.2
61
. I
6.0
7.4
8.3
7.8
7.3
4.5
4.0
-
-
SVI
-
97
O O
88
98
75
81
87
84
100
88
-
-
PH
7.92
7.82
7-70
. 79
7.77
7.36
7.35
7.27
7.17
7.03
7.06
7.78
6.94
COD
411
77
-7 r\
72
148
165
188
104
157
119
81
155
63
P
6.2
4.9
4-»
. 7
6.5
7.5
6.1
5.3
5.7
5.8
5.8
5.0
6.0
TKN
30.0
28.0
f\S C
£O . ->
21.2
28.8
23.2
18.9
21.3
18.3
19.0
22.1
20.9
NH3-N
24.0
19.0
1 Q /.
lO.<4
18.4
16.6
15.0
13.6
13.2
14.0
13.9
19.5
17.9
N02-N N03-N Stalked Cilia
0.0
0.1
01
. 1
0.1
0.5
0.7
1.1
1.2
1.4
1.4
0.0
1.4
0.0
9'? 530/ml
110/ml '
0. 5
0.5
1 . 2
80 /ml
2.5
2.7
3.5
0.2
3.6
1 All samples were taken at the time indicated.
settling was analyzed for BOD and nutrients.
2 Units are mg./l. unless otherwise indicated.
3 J.T.U. units.
4 Velocity in ft/hr.
Supernatant after 30 minutes
- 71 -
-------
TABLE 17
INTENSIVE MIXED-LIQUOR EVALUATION
2:00 P.M. - June 25, 1969
Settling4 Free Swimming Cilia
Sample*
Common Feed Waste
Air Train
Inlet
Middle
Exit
Oxygen Train
Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Stage 6
Effluent
From Air
Clarifier
From Oxygen
Clarifier
BOD''
270
54
28
20
75
59
45
60
44
47
14
20
• TSS VSS
259 173
2487 1748
2364 1730
3088 2758
2428 2280
2630 2184
2356 2184
3108 2888
3116 2770
3012 2626
10 9
4 4
Turbidity
-
12.2
8.6
9.9
25.8
20.4
18.8
19.5
16.8
16.7
3.6
4.2
0 Velocity
-
6.4
7.5
9.1
9.4
9.5
8.0
8.0
6.9
7.1
-
-
SVI
-
96
85
50
71
64
99
75
82
85
-
-
PH
8.52
7.95
7.82
7.80
7.54
7.37
7.33
7.28
7.23
7.13
7.90
7.09
COD
441
116
81
73
108
143
155
110
135
-
71
69
P TKN
21.0 32.1
11.0 23.9
9.1 21.9
8.8 24.9
- 24.5
15.7 22.6
14.1 21.3
12.4 23.5
11.0 22.8
9.5 23.0
6.7 22.6
6.7 19.6
NH3-N
18.0
19.0
18.4
18.9
16.4
15.2
16.1
17.1
17.1
17.1
19.2
17.1
N02-N
0.0
0.0
0.0
0.0
0.9
1.1
1.2
1.3
1.3
1.3
0.0
1.8
N03-N Stalked Cilia
0.0
0.1
n n 410/ml _ 07
n i 110/ml
0. 1
0.4
0.6 _nrv/ ,
0.6 210/mi =
0.9 60/ml
1.4
1.8
0.0
0.9
1 All samples were taken at the time Indicated.
settling was analyzed for BOD and nutrients.
2 Units are mg./l. unless otherwise indicated.
3 J.T.U. units.
4 Velocity in ft/hr.
Supernatant after 30 minutes
- 72 -
-------
TABLE 18
INTENSIVE MIXED-LIQUOR EVALUATION
Sample
Common Feed Waste
Air Train
Inlet
Middle
Exit
Oxygen Train
Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Stage 6
Effluent
From Air
Clarifier
From Oxygen
Clarifier
BOD2
245
44
50
30
25
50
13
54
34
35
27
33
17
38
18
27
15
24
10
17
7
18
5~
TSS
168
2868
3278
3402
2666
3064
3176
3804
3610
3830
9
11
VSS
124
1896
2112
2210
1824
2106
2126
2656
2442
2624
9
11
9:00 A.M. - June 26,
Settling4
Turbidity Velocity SVI pH
-
6.6 , ,
2.0 6'1
4.8 5.7
1.5
3.5 5.1
1.4
14.4 _
1.4
11.9 7.5
1.3
7.5 5.9
1.1
6.4 2.9
1.6
8.6 5.5
1.3
7.0 4.0
1.3
2.4
1.3
3.4
l.i
8.62
98 7.92
94 7.88
97 7.83
88 7.60
80 7.58
92 7.39
100 7.19
86 7.10
90 7.08
7.87
7.10
1969
COD
251
-
49
71
69
104
29
123
54
87
42
74
42
76
42
73
41
90
62
59
32
7fi
67
P
7.3
5.8
5.4
5.5
5.2
5.8
5.6
5.5
5.0
5.2
4.8
5.5
5.0
7.0
5.8
6.5
6.2
7.2
6.2
5.6
5.1
6.7
6.4
TKN
39.5
23.8
21.8
18.8
18.0
16.8
16.1
25.0
23.0
23.2
21..6
16.4
15.6
13.6
13.0
12.8
11.3
15.2
10.7
15.1
14.5
14.6
13.8
NH3-N
32.1
20.5
20.1
16.0
15.9
15.5
15.0
20.0
19.8
18.0
17.5
17.1
14.5
12.5
11.8
10.8
10.9
10,6
9.6
14.0
13.5
12.5
12.2
NOZ-N
0.0
0
0
0
0
0
0
0.8
0.8
1.1
1.1
1.4
1.2
1.6
1.3
1.6
1.3
1.7
1.5
0.0
0.0
1.5
1.4
Free Swimming Cilia
N03-N Stalked Cilia
0.1
0.1
0.1
0.1 500/ml ,
0.1 100/ml
0.1
0.0
0.9
0.9
1.5
1.3
270/ml „
-— 100/ml '
2.0
1.4
3.3
2.9
3.6
2.7
0.0
0.0
4.1
4.0
1 All samples were taken at the'time indicated. Supernatant after 30 minutes
settling was analyzed for BOD and nutrients.
2 Units are mg./l. unless otherwise indicated.
3 J.T.U. units
4 Velocity in ft/hr.
5 Where two values are indicated for BOD, Turbidity, COD and etc. . Unfiltered Supernatant/Filtered
Supernatant was analyzed.
- 73 -
-------
Evaluation of an Oxygenation System at High Treatment Rates and High
Mixed-Liquor Solids Concentration - Phase II Operation
The operation of only three stages of the six stage oxygenation
unit in treatment of the entire influent raw sewage flow at the Batavia
facility has been shown schematically in Figure 5. During this test
period, three of the four aeration bays at the plant were taken out of
service, including the entire air aerated system and one half of the
oxygenation unit. This reduction in effective aerator volume from a
total of 650,400 gal. (as in Phase I operation) to 162,600 gal. permitted
operation at a 3 to 4 fold higher treatment rate. Both existing clarifiers
were operated with the three stage oxygenation unit.
The dry weather months of July and August,1969 were selected as the
most desirable time to conduct this phase of oxygenation system testing.
During this period, raw sewage flows to the plantware nearly the design
flow of 2.5 MGD and waste strength was high (BOD of approximately 200 mg/1
or greater). Conversion of the system to this mode of operation was
completed in the first two weeks of July,1969. During the third week of
the month, the activated sludge level in the three stage oxygen unit was
allowed to build and the biomass was acclimated to high rate treatment.
Continuous data acquisition from the unit was begun in the week of July 21
and was carried out through the first week in September, 1969.
During this period of operation, all aeration equipment and process
control and monitoring instrumentation functioned as planned, requiring
no more than normal service maintenance. The conversion of the oxygen-
ation system to three stage operation required only the relocation of
feed oxygen and dissolved oxygen control valves. An influent sewage line
already existed to transport the wastewater flow to the newly designated
Stage No. 1 of the oxygen system. A recycle sludge line extention
(temporary) was put in place during construction to transport return
sludge to the first stage of the system. This extension passed through
the first three stages of the original six stage system. A larger
- 74 -
-------
(10-inch diameter) magnetic flow meter was installed in the oxygen system
sludge return line replacing the existing 4-inch diameter flow meter. This
was necessary to permit the recycle sludge from both clarifiers to pass
through the same return line to the oxygen unit.
Sufficient excess recirculation blower capacity existed for each
oxygen stage aerator to allow for the required increase in gas recirculation
rates within a given stage. In general,the Stage No. 2 and No. 3 blowers
having 85 cfm capacity were run at near maximum output to maintain a D.O.
concentration of 8-10 mg/1. The 180 cfm blower on Stage No. 1 was operated
at varying recirculation rates by automatic control to maintain the set
point mixed-liquor D.O.
The system conditions predetermined for this described mode of
operation were basically maintenance of an MLSS concentration of 6000-8000
mg/1 (MLVSS of 4000-4500 mg/1) at a mixed-liquor D.O. concentration of
8-10 mg/1. The aeration detention time in the system would be 1.5 hours
(based on raw sewage flow only) at the 2.5 MGD plant design flow. Aeration
detention time including total throughput, raw flow plus recycle flow,
would be 1.1 - 1.2 hours.
Examination of summary data shown in -Tables 19 and 20 clearly
indicate that operation of the three stage oxygenation unit at very
nearly the project plan conditions was possible throughout this phase
of testing. A summary of weekly averages for this period indicates a
24-hour influent raw sewage flow of approximately 2.50 MGD with a BOD
concentration of approximately 220 mg/1. Mixed-liquor suspended solids
concentrations in the range of 6400-7400 mg/1 were maintained, the seven
week average MLSS concentration being 6979 mg/1. A seven week average
MLVSS concentration of 4451 mg/1 was observed. The dissolved oxygen
concentration in the mixed-liquor of all oxygenation stages was maintained
at an average value of 9.0 mg/1 for the test period. The final clarifiers
were operated at an average sludge recycle/influent raw sewage flow ratio
of 0.34 for the test period. The recycle sludge averaged 2.9570 suspended
- 75 -
-------
TABLE 19
PHASE II OPERATION - OXYGEN SYSTEM PERFORMANCE
Weekly Average of Daily Values
PARAMETER
Wastewater Feed
Rate in MGD
Sludge Recycle
Rate as MGD
Sludge Recycle to
Raw Waste Feed
Rate Ratio
Wastewater
Temp. °F
Mixed-Liquor D.O.
as Average mg/1
Clarifier Effluent
D.O. in mg/1
Aeration Detention
Time in Hours
(Wastewater & Recycle)
Mixed-Liquor pH
Clarifier Overflow
Rates as Gal/Ft2 /Day
Nominal Aeration
Detention Time in
Hours (Wastewater only)
PERIOD
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Daily Average
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Inlet Stage 1
Middle Stage 4
Outlet Stage 6
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
7/21/69
2.17
3.53
2.77
0.69
0.81
0.73
0.31
0.23
0.27
60
11.8
10.4
11.1
7.1
0.6
3.2
1.4
0.9
1.2
864
1405
1102
1.8
1.1
1.4
7/28/69
2.28
3.48
2.93
0.64
0.77
0.71
0.28
0.23
0.25
68
11.6
10.2
10.8
0.9
0.3
0.5
1.3
0.9
1.1
907
1385
1166
1.7
1.1
1.3
8/4/69
2.03
2.89
2.50
0.80
0.85
0.83
0.39
0.30
0.34
67
10.5
9.6
10.0
0.1
0.3
0.2
1.4
1.1
1.2
7.8
7.7
7.6
808
1150
995
1.9
1.4
1.6
8/11/69
2.13
2.56
2.37
0.79
0.93
0.87
0.37
0.37
0.37
66
11.1
8.0
9.4
0.8
0.3
0.5
1.4
1.1
1.2
6.9
6.9
6.7
848
1019
943
1.8
1.5
1.6
8/18/69
2.07
2.90
2.52
1.07
1.01
1.04
0.52
0.35
0.43
72
9.5
6.1
7.6
0.3
0.1
0.1
1.2
1.0
1.1
6.7
6.7
6.6
824
1154
1003
1.9
1.3
1.5
3/25/69
1.79
2.84
2.36
0.72
0.87
0.80
0.40
0.31
0.35
69
10.6
5.2
7.7
0.1
0.0
0.1
1.6
1.1
1.3
6.9
6.9
6.8
712
1130
939
2.2
1.4
1.6
9/1/69
1.84
2.65
2.?.7
0.77
0.89
0.83
0.42
0.33
0.37
62
10.0
3.4
6.5
0
0
0
1.5
1.1
1.3
732
1054
903
2.1
1.5
1.7
- 76 -
-------
TABU: 20
PHASE II OPERATION - OXYGEN SYSTEM PERFORMANCE
Weekly Average of Daily Values
PARAMETER
VSS of Feed
Wastewater^mg/l
Mixed Liquor TSS,mg/l
Mixed Liquor VSS,mg/l
Recycle Sludge TSS,
rag/1
Recycle Sludge VSS,
Recycle Sludge
VSS /TSS Ratio
Sludge Volume Index
Initial Sludge
Settling Rate Ft/Hr
Dry Solids Wasted,
Ibs/day
Lbs. VSS Wasted
per Lb. BOD Removed
Food/Biomass as
Ib BOD/lb MLVSS
Volumetric Organic
Loading as Ib BOD/
Day/1000 ft3 Mixed
Liquor
Effluent
Turbidity as J.T.U.
PERIOD
Night
Day
24 Hour Mean
24 Hour Mean
24 Hour Mean
24 Hour Mean
24 Hour Mean
24 Hour Mean
24 Hour Mean
24 Hour Mean
Each 24-Hours
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
7/21/69
104
176
124
6,464
3,588
33,942
18,854
0.56
39
7.6
*
*
0.580
1.972
1.344
129.8
442.3
300.8
7/28/69
90
125
107
7,134
4,242
33,714
20,909
0.60
22
8.6
2,953
0.503
0.479
0.959
0.705
125.7
242.5
179.1
6.6
7.5
7.6
8/4/69
79
109
98
7,388
4,831
28,511
18,047
0.64
34
6.5
1,945
0.423
0.323
0.680
0.519
97.7
205.7
156.2
8.6
8.3
8.4
8/11/69
123
171
134
7,348
4,806
26,787
17,445
0.65
42
4.7
2,396
0.368
0.551
0.826
0.704
165.6
246.0
211.4
8.6
10.6
9.8
8/18/69
83
195
153
6,759
4,401
24,782
16,182
0.65
41
5.5
2,933
0.401
0.593
1.143
0.887
163.4
321.9
248.3
6.8
7.6
7.3
8/25/69
139
157
150
6,535
4,354
29,594
18,542
0.63
33
7.3
2,013
0.364
0.357
0.977
0.693
97.4
257.3
184.0
9.5
10.0
9.8
9/1/69
65
110
93
7,227
4,936
29,599
17,328
0.59
41
5.6
*
-*
0.405
0.902
0.675
124.4
278.5
207.9
15.0
9.8
11.7
- 77 -
-------
solids (29,561 mg/1) during the seven week period. Individual weekly
average recycle sludge TSS concentrations as high as 3.470 are reported.
On specific occasions, when the manually controlled sludge return pumps
were carefully monitored, recycle sludge concentrations as high as 5%
could readily be achieved. This recycle sludge had a light brown
coloration and microscopic examination clearly indicated its viability.
No odor or black to dark grey coloration indicative of sustained
anaerobic conditions was evident.
As indicated in Table 21, oxygen was introduced to the three stage
oxygenation unit at a 24-hour average rate of about 31 cfm throughout the
seven week period. Gas was exhausted from the unit at an average rate
of 4.0 cfm with an oxygen content of 557o. On an overall average basis,
an oxygen utilization efficiency of 92.7% was observed. Throughout the
course of the test period,this feed oxygen utilization efficiency varied
by only about - 1% from the mean. This may be taken as an indication of
the highly reliable nature of the feed oxygen control system.
The overall power requirements for liquid mixing and gas recirculation
in the oxygenation unit are shown in Table 22. Also shown are average
power requirements per system stage on a 24-hour basis. In summary,these
data indicate the distribution of power input to be an average of 11.1 HP
for liquid mixing and 9.2 HP for gas recirculation within the stages. A
total average power input for the seven week oxygenation system operation
of 20.3 HP was observed. This power input and distribution differed from
Phase I operation (26 HP for liquid mixing and 2.6 HP for gas recirculation)
since more than twice the total quantity of oxygen was transferred to the
mixed-liquor per day and yet three less oxygenation stages were used.
The mixing energy input was thus decreased due to a smaller volume of
mixed-liquor under aeration while the gas recirculation energy input was
increased to meet the higher daily oxygen demand. On a unit aeration tank
volume basis,the oxygenation system operated at a power input of 0.125 HP
per 1000 gallons of mixed-liquor in Phase II of the study. Day to night
and week to week variations in this value are listed. The power consumption
- 78 -
-------
TABLE 21
PHASE II OPERATION - OXYGEN SYSTEM PERFORMANCE
PARAMETERS
Total Feed Oxygen
Flow Rate,CFM at
NTP
Average % Oxygen
Composition in
Gas Space of
each Oxygen
System Stage
Exhaust GPS Rate
From Oxygen
System 3rd Stage,
CFM at NTP
Overall 7, of Feed
Oxygen Utilization
Lb. Oxygen Utilized
per Lb . BOD
Consumed
Oxygen Absorbed
as Lb./Hr.
PERIOD
Night
Day
24 Hour Mean
24 Hr. Mean-Stage
1
2
3
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
7/21/69
33.1
36.3
34.3
82
73
52
4.64
4.81
4.82
94.8
92.0
92.9
1.54
0.46
1.32
156.0
166.1
158.5
7/28/69
25.7
32.6
29.4
82
70
54
3.13
4.10
3.66
93.2
93.2
93.2
1.19
0.76
0.93
119.0
150.9
136.3
8/4/69
28.7
32.8
30.9
84
73
58
4.75
4.87
4.82
90.6
91.2
91.0
1.76
0.91
1.13
129.1
148.6
139.7
8/11/69
29.3
31.5
30.5
82
72
57
4.67
3.89
4.24
90.6
92.9
91.9
1.41
0.69
0.80
131.8
145.7
139.3
8/18/69
30.8
32.2
31.6
82
71
54
3.31
3.81
3.58
94.0
93.5
93.8
1.10
0.58
0.74
144.2
149.5
147.1
8/25/69
27.5
32.2
30.0
83
72
55
3.54
3.87
3.72
92.7
93.4
93.1
1.73
0.72
0.96
126.8
149.3
139.0
9/1/69
29.1
31.9
30.7
82
73
56
3.73
3.25
3.47
92.6
94.2
93.6
1.44
0.64
0.84
134.7
149.6
142.8
- 79 -
-------
TABLE 22
PHASE II OPERATION - OXYGEN SYSTEM PERFORMANCE
Weekly Average of Daily Values
PARAMETER
Power Required
for Liquid Mixing
in Oxygen
System Per Stage
as Hp
Power Required
for Gas Recirculation
in Oxygen
System per Stage
as Hp
Overall Power
Required for Liquid
Mixing as ftp
Overall Power
Required for Gas
Recirculation as Hp
Overall Power
Utilized as Hp/1000
Gal of Mixed Liquor
PERIOD
24 Hour Stfge
Mean 2
3
Stage
24 Hour 1
Mean 2
3
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
7/21/69
6.0
2.8
3.2
4.3
1.8
2.7
12.0
11.9
11.9
6.1
10.3
8.7
0.111
0.137
0.127
7/28/69
5.9
2.8
3.0
3.6
2.6
2.4
12.3
11.2
11.7
7.1
9.9
8.6
0.119
0.119
0.125
8/4/69
5.9
2.8
2.7
2.7
2.6
2.5
11.4
11.3
11.4
6.5
8.8
7.7
0.110
0.124
0.117
8/11/69
5.6
2.7
2.1
4.4
2.5
2.4
10.7
10.3
10.5
8.8
9.8
9.4
0.120
0.124
0.122
8/18/69
5.8
2.8
2.3
4.5
2.5
2.4
11.0
11.1
11.0
8.8
9.7
9.3
0.122
0.128
0.125
8/25/69
5.9
2.7
2.6
4.8
2.6
2.5
11.3
11.1
11.2
8.3
11.1
9.8
0.120
0.137
0.129
9/1/69
5.5
2.7
2.0
6.0
2.6
2.4
10.5
10.0
10.2
11.1
11.0
11.1
0.133
0.129
0.131
- 80 -
-------
per unit mixed-liquor volume is somewhat higher than necessary in this
case due to the lack of availability of the proper combination of pulleys
to decrease the mixer drive speeds.
The treatment effectiveness of the high rate oxygenation system is
described by the dat-.i in Tables 23, 24, and 25. On a seven week average
basis, 90% of the average 220 mg/1 of influent BOD was removed while the
system operated at an aeration detention time of 1.2 hours (raw sewage
and recycle sludge flow with a tank volume of 162,000 gallon). During
the day and thus during peak organic loading,the aeration detention
time averaged 1.0 hour. For the entire period of operation,a COD removal
efficiency of 71% is indicated with an average influent COD concentration
of 325 mg/1. The data in Table 23 also indicates that an average of 89%
of influent suspended solids (174 mg/1) was removed.
These removals were achieved at the organic loading and food/biomass
ratio values shown in Table 20, at averages of 212.5 Ibs. BOD/day/1000 ft3
mixed-liquor and 0.790 Ibs. BOD/lb. MLVSS,respectively. On a seven week
average basis, day time (10:00 a.m. - 11:00 p.m.) organic loading rates
averaged 284.9 Ibs. of BOD/day/1000 ft3 of mixed-liquor and food/biomass
ratios averaged 1.066 Ibs. BOD/lb. MLVSS under aeration.
Listed in Table 24 are weekly average values for total phosphate
analysis of feed wastewater and final clarifier effluents. Influent
phosphate (as mg/1 P) levels during the seven week test period averaged
12 mg/1 on a 24 hour basis with comparable clarifier effluent concentrations
of 10 mg/1, yielding a 12% overall removal efficiency. As in the air and
oxygen comparison during the initial test period at Batavia, digester
supernatant was returned to the aeration tanks. In this second phase of
operation, however, the phosphorous content of the digester supernatant
was not monitored in the feed waste composite sampling system. The
supernatant was returned to the aeration tanks via the influent sewage
line in the Phase I comparison, but limitations in piping required that
this stream be returned via the sludge recycle lines in Phase II operation.
- 81 -
-------
TABLE 23
PHASE II OPERATION - OXYGEN SYSTEM PERFORMANCE
PARAMETER
Feed Wastewater
BOD,mg/l
Clarifier Effluent
BOD, mg/1
% BOD Removed
Feed Wastewater
COD, mg/1
Clarifier Effluent
COD, mg/1
% COD Removed
Feed Wastewater
TSS,mg/l
Clarifier Effluent
TSS,mg/l
% TSS Removed
WEEK
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
*•***/
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
** j
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
" j
24 Hour Mean
7/21/69
156
326
283
22
31
29
86
91
90
243
386
240
114
100
105
53
74
68
207
323
209
15
24
22
93
93
89
7/28/69
145
190
166
19
25
22
87
87
87
188
308
265
91
108
100
52
65
62
96
156
118
12
17
15
88
89
87
8/4/69
125
185
163
21
22
22
83
88
87
205
340
290
102
65
73
50
81
75
114
143
133
14
13
13
87
91
90
8/11/69
202
252
232
20
19
18
90
92
92
368
442
405
120
123
122
67
72
70
164
231
203
17
19
18
90
92
91
8/18/69
205
282
252
22
29
26
89
90
90
257
441
372
72
121
103
72
73
72
122
331
253
21
23
22
83
93
91
8/25/69
141
236
203
24
27
26
83
89
87
268
335
312
86
61
70
68
82
78
144
205
184
26
23
24
82
39
87
9/1/69
176
274
238
30
18
23
83
93
91
424
370
390
103
99
101
76
73
74
97
131
119
17
18
18
83
86
85
- 82 -
-------
TABLE 24
Weekly Average of Daily Values
PARAMETER
Total Phosphate in Feed
Wastewater as
mg/1 of P
Total Phosphate in
Clarifier Effluent
as mg/1 of P
Total % Phosphate
Removed
Ammonia Nitrogen
in Feed Wastewater
as mg/1 N
Ammonia in Clarifier
Effluent as
mg/1 N
TKN in Feed
Wastewater as
mg/1 N
TKN in Clarifier
Effluent as
mg/1 N
N02 Nitrogen in
Feed Wastewater
as mg/1 N
N02 Nitrogen in
Clarifier Effluent
as mg/1 N
PERIOD
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
7/21/69
7
7
7
7
8
8
-5
-24
-17
10
13
12
9
12
11
19
11
14
13
0
0
0
0.2
0.2
0.2
7/28/69
5
12
10
7
10
9
-24
16
8
9
16
13
10
21
17
18
25
22
13
23
20
0.3
0.0
0.1
0.2
0.1
0.1
8/4/69
8
14
12
9
11
10
-2
23
17
15
22
19
15
22
20
27
36
33
20
28
25
0.1
0.0
0.0
0.1
0.2
0.2
8/11/69
9
16
13
9
10
9
-2
37
26
17
24
21
13
17
15
30
41
36
20
24
22
0
0
0
0.1
0.2
0.3
8/18/69
9
20
16
9
12
11
-4
41
32
17
31
26
16
25
21
29
50
42
23
32
28
0
0
0
0.1
0.2
0.1
8/25/69
9
16
13
10
13
12
-20
20
11
15
21
19
16
21
21
27
35
32
22
26
25
0
0
0.1
0.2
0.2
9/1/69
8
17
13
10
12
11
-20
30
19
18
25
23
14
20
18
30
37
35
18
24
22
0
0
0.2
0.2
0.2
- 83 -
-------
TABLE 25
PHASE II OPERATION - OXYGEN SYSTEM PERFORMANCE
Weekly Average of Daily Values
PARAMETER
N03 Nitrogen in
Feed Wastewater
as mg/1 N
N03 Nitrogen in
Clarifier Effluent
as mg/1 N
Total Nitrogen in
Feed Wastewater
as mg/1 N
Total Nitrogen in
Clarifier Effluent
as mg/1 N
7,, Total Nitrogen
Removed
N03 - N/Total N
in Feed Wastewater
N03 - N/Total N
in Clarifier Effluent
PERIOD
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
Night
Day
24 Hour Mean
7/21/69 7/28/69
0 0.6
0 0.1
0 0.3
1.0 1.1
0.6 1.3
0.7 1.2
19 19
25
23
12 14
25
21
37 23
2
7
0 0.07
0
0.03
0.08 0.08
0.06
0.07
8/4/69
0.3
0.1
0.2
1.6
2.0
1.8
27
36
33
21
30
27
22
18
18
0.01
0.00
0.01
0.07
0.07
0.07
8/11/69
0.1
0.1
0.1
1.4
2.1
1.8
30
41
37
21
27
24
29
35
33
0
0
0
0.07
0.08
0.08
8/18/69
0.1
0.2
0.2
1.8
2.1
2.0
29
50
42
24
34
30
15
32
28
0
0
0
0.07
0.07
0.07
8/25/69
0.1
0.1
0.1
1.8
2.1
2.1
28
35
32
23
29
27
16
18
17
0
0
0
0.08
0.07
0.07
9/1/69
0.0
0.1
0.1
1.7
2.2
2.0
30
37
35
20
26
24
33
30
31
C
0.08
0.08
0.08
Lbs. Total Nitrogen
Removed per Lb. of
Dry Solids Wasted
24 Hour Mean
0.025 0.064 0.107 0.086 0.049
- 84 -
-------
It was not then possible to arrive at a valid phosphorus balance in
this phase of operation. This is noted in the seeming disparity in
phosphorus removal rates between the first and second phases of
operation.
In Tables 24 and 25 are listed the weekly average values for the
analysis of influent wastewater and clarifier effluent for NH3-N, TKN,
N02-N, and N03-N. On an overall basis,an average of 237» of influent
nitrogen was removed in the treatment process. Ammonia nitrogen
concentrations of influent wastewater were on the average equivalent
to Phase I operation values. TKN, however, appears to be divided
nearly equally between organically bound and free ammonia nitrogen.
Nitrification again occurred in the oxygenation system mixed-liquor to
a limited extent. On a seven week average basis,the N03-N/total
clarifier effluent nitrogen ratio was 0.07,indicating only 7% nitrifi-
cation of effluent nitrogen. In the case of these nutrient analyses
listed in Tables 24 and 25, whole rather than filtered effluent samples
were used for the various determinations.
Certain of the physical characteristics of the mixed-liquor biomass
are listed on a weekly average basis in Table 20. Most remarkable is the
consistently low SVI of the mixed-liquor throughout the seven week period,
the average value being 36. In addition to this high degree of compaction,
an average initial settling velocity of 6.5 ft/hr. was observed. This
settling rate is unusually high for a TSS concentration averaging 6980 mg/1
in the mixed-liquor. The VSS/TSS ratio 6f the recycled activated sludge
averaged 0.62 for the seven week test period. An average of 2448 Ibs. of
dry solids having this fraction of volatile solids content were wasted
from the system each day. In relation to the air system dry solids
wasting information from the initial phase of operation, the three stage
oxygen unit assimilated nearly twice the quantity of BOD in this phase of
operation yet produced less excess sludge than the air aeration system
while operating at lower treatment rate. The information in Table 20
indicates that an average of 0.38 Ibs. excess VSS were produced by the
- 85 -
-------
oxygenation system per Ib. of BOD removed. The significance of this
observation will be discussed.
In Table II of the Appendix to this report are listed on a weekly
basis results of analyses of mixed-liquor supernatant fractions for
organic and inorganic nutrients for Phase II operation. Samples from all
liquid stages were taken (grab samples) and analyzed as outlined. These
results serve to illustrate the effect of liquid staging on removals
throughout the system. Mixed-liquor supernatant rather than filtrate
was used for analysis in all cases.
Air and Oxygenation Systems Performance Comparison at Hiffh Treatment
Rates and High Mixed-Liquor Solids Concentrations - Phase III Operation
In the final phase of the test program,parallel evaluation of air
and oxygen aerated activated sludge treatment systems was again carried
out, differing in several respects from the comparison in the initial
phase operation. A diagram of the two systems has been shown in Figure 6.
During July and August, 1969, a period when the air aeration bays
were out of service, temporary modifications were made on the air system
in anticipation of the final phase of operation. The second in the series
of two aeration bays was cleaned (10 yds3 of silt were removed) and
separated from the first air system tank by a temporary water-tight bulk-
head. A recycle sludge line extension was installed so that recycle
sludge might be returned to the second rather than first air aeration
tank. Liquid staging baffles were installed in the second air aeration
tank so that liquid staging identical to the three stage oxygenation
system was accomplished. The first air aeration bay was not returned
to service. These modifications made it possible in the final test period
to operate parallel air and oxygen systems having the same aeration volume
(162,600 gal. each) and the same liquid staging characteristics. The only
major difference in the two systems was the mode of aeration. At a
plant design influent flow rate of 2.5 MGD, each system would operate at
an aeration detention time of approximately 3 hours without consideration
- 86 -
-------
of recycle sludge flow rates. By the predetermined project plan,it was
intended that the oxygenation unit be operated at an MLSS concentration
of 6000-8000 mg/1 and a mixed-liquor D.O. concentration of 8-10 mg/1 while
treating one half of the influent sewage. It was intended that the air
aeration system as modified should be operated at the maximum attainable
MLSS level consistent with good practice (3000-4000 mg/1 preferably) and
at an aeration rate sufficient to maintain 2.0 mg/1 of D.O. in the mixed-
liquor. Fifty percent more diffusers than normal were installed in the
air aeration tank and the option of tapering the areation rate along the
length of the tank was possible by control of manual valves on each
diffuser bank header.
Since no changes were necessary in the oxygenation unit following the
second test period, it was possible to immediately begin operation of the
parallel systems in the second week of September,1969. The source of
seed activated sludge for the air system was the oxygenation system mixed-
liquor. This sludge was permitted to acclimate for six days before
continuous data taking was initiated.
With few exceptions,the process monitoring and control instrumentation
functioned without difficulty throughout this test period. Continued
difficulties with recycle sludge magnetic flow meters were encountered.
T'ith the high level of influent suspended solids and rags, plugging of
the air system return sludge meter occurred occasionally. Grease build-up
on the flow sensing elements of the recycle sludge flow meters necessitated
frequent cleaning since sensitivity often varied. Two weeks of values
from these meters have been excluded from the data to be presented here
because of apparent inaccuracies. Additionally,the 10-inch diameter
sludge return meter installed in the oxygen system during the previous
phase of operation created some unusual difficulties. It was not possible
to return sludge at less than 0.5 MGD rate to the oxygen system. Lack of
resistance to flow in this return line decreased the head to which the
air lift return pump must lift sludge in the gravity flow sink. Since
each pump is capable of an 0.8 MGD rate and the performance curve is flat,
- 87 -
-------
attempts to decrease the pumping rate below 0.5 MGD by lowering the air
rate resulted in a loss of pumping action. Decreasing the flow to the
oxygenation system by partial closing of the recycle sludge line control
valve caused line clogging. This annoying difficulty, unique to this
set of circumstances, resulted in unusually high recycle rates and
commensurately lower TSS concentration of recycle sludge. The 4-inch
meter restriction in the air system sludge return line prevented this
difficulty from occurring in that system.
Unusually high BOD, COD, and suspended solids concentrations of the
influent sewage in October and early November made operation of the air
system at high solids levels (approximately 4000 mg/1 TSS) very difficult.
Dissolved oxygen was limited during day time operation resulting in odor
problems from the final clarifier and open sludge return sink. Maximum
aeration rates for the number of diffusers present was used. Optimum
performance and odor control were achieved for the air system by reducing
MLSS concentrations to 3000-3500 mg/1 and reducing the influent raw
sewage rate by shifting the balance of the flow to the oxygenation unit
which was not D.O. limited. These operational changes are reflected in
the data included here.
On observation which was not quantitatively recorded is the appear-
ance of the waste activated sludge from each system. While the oxygenation
unit sludge was light brown in appearance and odor free, the air system
waste sludge was visually dark and by odor appeared anaerobic. Although
not quantitatively ascertained, a large portion of BOD and COD removed in
the air unit appears to have been sorbed and removed from the system as
waste sludge without being oxidized. This would be expected under oxygen
limiting conditions.
The information in Tables 26 and 27 describe the operating conditions
for the air and oxygenation systems during this nine week period of
continuous data acquisition. On an overall basis, average wastewater flows
of 1.29 MGD and 1.44 MGD were influent to the air and oxygenation systems,
- 88 -
-------
TABLE 26
PHASE III OPERATION - AIR AND OXYGEN SYSTEMS PERFORMANCE COMPARISON
PARAMETER PERIOD
Wastewater Feed Night
Rate in MGD Day
24 Hour Mean
Sludge Recycle Night
Rate in MGD Day
24 Hour Mean
Sludge Recycle to Night
Raw Waste Feed Day
Rate Ratio 24 Hour Mean
Wastevater Temp. °F Daily Avg.
Mixed Liquor D.O. Night
as Average rag/1 Day
24 Hour Mean
Clarifier Effluent Night
D.O. in mg/1 Day
24 Hour Mean
Aeration Detention Night
Time in Hours Day
(Wastewater 6. Recycle) 24 Hour Mean
Nominal Aeration Night
Detention Time in Hours Bay.
(Wastewater Only) 24 Hour Mean .
Mixed-Liquor pH Inlet Stage I
Inlet Stage 2
Inlet Stage 3
9/8/69
AIR OXYGEN
1.04 1.01
1.32 1.59
1.19 1.33
0.30 0.66
0.33 0.73
0.32 0.70
0.31 0.71
0.27 0.46
0.28 0.57
66 66
2.5 8.7
0 6.7
1.2 7.6
0 9.1
0 6.5
0 7.4
3.0 2.5
2.4 1.7
2.7 2.1
3.7 3.8
2.9 2.4
3.3 2.9
7.2 6.5
6.9 6.4
7.1 6.3
9/15/69
AIR OXYGEN
1.31 1.03
1.51 1.50
1.42 1.29
0.25 0.73
0.24 0.67
0.25 0.70
0.20 0.73
0.16 0.45
0.18 0.58
73 73
1.2 9.8
0.1 9.5
0.6 9.6
0 7.1
0 6.1
0 6.4
2.5 2.2
2.2 1.8
2.4 2.0
3.0 3.8
2.6 2.6
2.7 3.0
7.1 6.5
6.9 6.4
7.0 6.3
9/22/69
AIR OXYGEN
1.27 1.19
1.49 1.54
1.39 1.38
0.25 0.75
0.23 0.79
0.24 0.77
0.20 0.65
0.16 0.58
0.18 0.61
72 72
1.2 9.2
0.1 9.2
0.6 9.2
0 3.6
0 2.0
0 2.6
2.6 2.0
2.3 1.7
2.4 1.9
3.1 3.3
2.6 2.5
2.8 2.8
7.1 6.7
7.2 6.5
7.2 6.3
Weekly
9/29/69
AIR OXYGEN
1.04 1.00
1.35 1.35
1.21 1.19
0.29 0.52
0.25 0.55
0.27 0.54
0.29 0.55
0.19 0.42
0.23 0.48
72 72
1.9 6.4
0.9 6.6
1.4 6.5
0 2.9
0 1.5
0 2.1
3.0 2.7
2.5 2.1
2.7 2.3
3.7 3.9
2.9 2.9
3.2 3,3
7.3 6.7
7.3 6.6
7.3 6.5
- 89 -
Average of Da 11}
10/6/69
AIR OXYGEN
0.99 1.16
1.22 1.53
1.11 1.36
0.25 0.58
0.22 0.52
0.23 0.55
0.25 0.51
0.22 0.35
0.24 0.42
71 71
1.7 6.9
0.2 6.7
0.8 6.8
0 1.8
0 1.2
0 1.5
3.2 2.3
3.0 2.0
3.1 2.1
3.9 3.4
3.2 2.5
3.5 2.9
Values
10/13/69
AIR OXYGEN
0.97 1.21
1.42 1.58
1.21 1.41
0.21 0.52
0.19 0.53
0.20 0.53
0.24 0.50
0.14 0.34
0.18 0.41
70 70
1.1 5.9
0.1 5.7
0.6 5.8
0 5.2
0 3.7
0 4.3
3.4 2.3
2.4 1.9
2.9 2.1
4.0 3.2
2.7 2.7
3.2 2.8
10/20/69
AIR OXYGEN
1.12 1.38
1.39 1.54
1.26 1.47
67 67
0.9 7.4
0.3 6.7
0.6 7.0
0 4.9
0 2.5
0 3.6
3.1 2.8
2.8 2.5
3.1 2.6
10/27/69
AIR OXYGEN
1.11 1.53
1.53 1.73
1.34 1.64
0.57
0.47
0.52
0.37
0.27
0.32
68 68
1.7 9.6
0 9.2
0.8 9.4
0 6.4
0 4.8
0 5.5
2.0
1.8
1.9
2.9 2.4
2.5 2.3
2.9 2.4
7.3 6.8
7.3 6.8
7.2 6.6
U/3/69
AIR OXYGEN
1.20 1.81
1.72 1.89
1.48 1.85
0.26 0.46
0.22 0.48
0.24 0.47
0.22 0.25
0.13 0.25
0.17 0.25
68 68
0.9 10.1
0 10.2
0.4 10.2
0.1 5.4
0 5.3
0.1 5.4
2.7 1.8
2.0 1.7
2.3 1.7
2.6 2.2
2.3 2.1
2. .6 2.1
6.8 6.1
6.7 6.0
6.6 5.9
-------
TABLE 27
PHASE III OPERATION - AIR & OXYGEN SYSTEM PERFORMANCE
Weekly Average of Dally Values
PARAMETER PERIOD
VSS of Feed Night
Wastewater, mg/1 Day
24 Hour Mean
Mixed Liquor TSS.ng/1 24 Hour Mean
Mixed Liquor VSS, mg/1 24 Hour Mean
Recycle Sludge TSS, rag/1 24 Hour Mean
Recycle Sludge VSS, mg/1 24 Hour Mean
Recycle Sludge 24 Hour Mean
VSS/TSS Ratio
Sludge Volume Index 24 Hour Mean
Initial Sludge 24 Hour Mean
Settling Rate,ft/hr
Dry Solids Waited, LBS Each 24 Houri
Lbs. VSS Wasted per Lb. 24 Hour Mean
BOD Removed
Food/Blomasa as Night
Ib BOD/lb MLVSS Day
24 Hour Mean
Volumetric Organic Night
Loading as Ib BOD/ Day
Day/1000 ft3 Mixed 24 Hour Mean
L iquor
Effluent Night
Turbidity as J.T.U. Day
24 Hour Mean
9/8/69
AIR OXYGEN
104 104
217 217
175 175
4340 5890
2980 3850
18,530 17,960
12,860 11,440
0.69 0.69
48 54
8.5 4.4
1791 319
0.613 C\,093
0.394 0.274
0.713 0.777
0.567 0.546
70.0 63.2
138.7 172.3
107.2 122.3
9.5 8.9
8.3 9.3
8.8 9.2
9/15/69
AIR OXYGEN
185 185
433 433
339 339
4290 6810
3130 4300
20,210 17,700
13,700 12,290
0.68 0.69
45 80
9.4 1.7
2943 334
0.875 0.105
0.391 0.200
0.722 0.528
0.571 0.378
53.1 72.9
146.3 145.6
121.0 110.7
5.4 6.7
5.5 6.3
5.4 6.4
9/22/69
AIR OXYGEN
270 270
277 277
274 274
3680 6840
2470 4380
16,680 16,260
11,310 10,300
0.68 0.63
46 57
7.9 4.2
4281 454
1.126 0.105
0.751 0.406
1.115 0.526
0.948 0.471
114.3 106.0
150.1 152.3
133.7 131.1
3.1 3.3
3.8 2.5
3.5 2.8
9/29/69
AIR OXYGEN
289 289
285 285
300 300
3180 5890
2290 3750
12,650 18,760
9,420 12,750
0.74 0.68
55 36
8.3 6,7
2937 371
0.893 0.093
0.855 0.383
1.190 0.724
1.036 0.568
101.8 98.8
161.3 158.9
130.1 127.5
6.4 7.6
6.8 5.4
6.6 6.2
- 90 -
10/6/69
AIR OXYGEN
557 557
278 278
370 370
2810 7400
2090 5440
13,540 18,870
9,680 13,170
0.71 0.74
77 34
7.2 6.3
3018 892
0.952 0.223
0.966 0.464
0.900 0.341
0.930 0.397
123.9 149.2
108.5 136.9
115.5 142.6
4.8 2.6
6.1 4.6
5.5 3.8
10/13/69
AIR OXYGEN
497 497
412 412
468 468
3890 5700
2800 3760
16,670 19,490
12,010 13,090
0.72 0.67
96 40
5.8 5.9
4842 396
1.247 0.077
0.595 0.453
1.110 0.905
0.915 0.686
87.1 130.1
178.6 202.5
136.9 169.4
4.1 1.3
4.7 2.0
4.5 1.7
10/20/69
AIR OXYGEN
367 367
382 382
376 376
3650 5620
2540 3960
15,770 19,060
11,340 13,170
0.72 0. 9
69 52
7.3 5.1
3779 623
1.019 0.131
0.797 0.517
0.782 0.573
0.789 0.547
122.4 148.6
145.6 160.8
135.0 155.2
3.3 2.1
4.7 2.6
4.2 2.4
10/27/69
AIR OXYGEN
343 343
320 320
339 339
3640 5560
2620 3960
18,580 21,500
13,400 14,370
0.72 0.67
73 41
6.4 6.0
4681 1028
1.262 0.198
0.650 0.689
1.092 0.842
0.889 0.772
107.5 155.7
162.7 182.8
137.4 170.4
4.9 3.8
5.4 3.0
5.2 3.3
11/3/69
AIR OXYGEN
294 294
390 390
346 346
3260 5970
2390 4330
16,810 19,580
12,870 13,870
0.77 0.71
60 50
8.4 5.4
3177 908
0.921 0.178
0.549 0.456
1.235 0.763
0.921 0.621
89.7 133.9
189.4 208.4
143.8 174.4
6.7 4.1
8.4 3.1
7.7 3.8
-------
respectively. Aeration detention times (raw sewage and recycle sludge
flow) for each system, air and oxygenation, were approximately 2.4 and
2.0 hours, respectively, on an average basis. Mixed-liquor suspended
solids concentrations were maintained at an average concentration of
6185 mg/1 in the oxygenation system and 3637 mg/1 in the air aeration
system. The corresponding average MLVSS concentrations were 4305 mg/1
and 2576 mg/1, respectively. During the nine week period, average
dissolved oxygen concentrations of 0.8 mg/1 and 8.0 mg/1 were maintained
in the respective air and oxygenation systems mixed-liquor. Clarifier
effluent D.O. for the oxygenation system averaged 4.3 mg/1 during the
nine week period while that of the air aerated system averaged 0.1 mg/1.
Recycle sludge concentrations as TSS averaged 16,600 mg/1 for the air
system and 18,790 mg/1 for the oxygenation unit. The recycle sludge
flow rate/raw sewage influent flow rate averaged 0.21 for the air aerated
treatment unit and 0.45 for the oxygen aerated unit. The reason for the
disparity between the two ratios has been indicated previously. Clarifier
overflow rates averaged 1027 and 1142 gal/ft2/day for the air and oxygen-
ation treatment systems, respectively.
Listed in Table 28 are weekly average values for the air aeration
rates used on both a 24-hour and day-night basis. Over the nine week
operation period, an average air aeration rate of 4.32 ft3/fal of sewage
treated was used. This required a net input of 138.5 air blower HP. As
indicated in Table 28, pure oxygen was fed to the multistage oxygenation
system at an average rate of 19.0 cfm during the nine week test period.
Gas was exhausted from the final stage of the oxygenation system at an
average rate of 3.22 cfm containing 51% oxygen. The overall average
oxygen utilization efficiency for the multistage system was 91.470. Also
shown in Table 28 are weekly average values for Ibs. oxygen utilized/lb.
BOD removed, an average of 0.72 Ibs. oxygen/lb. BOD for the entire test
period.
Listed in Table 29 is the weekly average power input to each stage
of the oxygenation system in terms of HP required for liquid mixing and
aeration gas recirculation to transfer the Ibs. of oxygen/hour noted in
- 91 -
-------
TABU 28
PHASE III OPERATION - AIR & OXYGEN SYSTEM PERFORMANCE
PARAMETER PERIOD
Ft3 Air Utilized Night
per Gallon Sewage Day
Treated, NTP 24 Hour Mean
Air Blower Power Night
Utilized aa Up Day
24 Hour Mean
Total Feed Oxygen Night
Flow Rate,CFM at Day
NTP 24 Hour Mean
Average % Oxygen 24 Hour St"8e
Composition in Mean 2
Gaa Space of 3
each Oxygen
Syaten Stage
Exhaust Gas Rate Night
from Oxygen Day
System Final Stage 24 Hour Mean
Overall 7. of Feed Night
Oxygen Utilized Day
24 Hour Mean
LB Oxygen Utilized Night
Per Ib. BOD Day
Consumed 24 Hour Mean
Oxygen Absorbed Night
aa Ib/hr Day
24 Hour Mean
9/8/69
AIR OXYGEN
5.69
4.12
4.75
153.2
139.9
145.9
17.9
21.9
20.1
78
67
51
3.14
2.26
2.66
90.5
94.6
93.0
1.58
0.73
0.93
80.8
102.8
92.7
9/15/69
AIR OXYGEN
4.22
3.69
3.91
142.4
143.2
142.8
16.3
18.4
17.4
78
67
50
2.08
2.07
2.08
93.7
94.1
94.0
1.28
0.71
0.90
76.0
86.2
81.5
9/22/69
AIR OXYGEN
4.38
3.66
3.96
140.0
137.3
138.6
17.2
19.7
18.6
80
69
54
2.70
2.25
2.46
91.7
93.6
92.8
0.87
0.69
0.76
78.5
91.8
85.7
9/29/69
AIR OXYGEN
5.48
4.05
4.62
143.2
138.1
140.4
18.5
21.3
20.0
80
71
53
2.99
3.28
3.15
91.8
91.5
91.6
1.03
0.72
0.84
84.2
97.1
91.2
- 92 -
10/6/69
AIR OXYGEN
5.57
4.59
4.99
138.8
140.7
139.9
13.0
19.4
16.5
75
66
46
1.68
2.10
1.91
94.0
94.7
94.4
0.47
0.78
0.63
60.9
91.9
77.7
10/13/69
AIR OXYGEN
5.57
3.38
4.18
133.3
118.6
125.3
18.1
22.7
20.6
80
70
47
4.48
4.90
4.70
88.1
90.2
89.6
0.76
0.59
0.64
79.9
102.0
91.9
10/20/69
AIR OXYGEN
5.21
4.87
5.01
144.4
167.1
156.7
18.9
21.3
20.2
80
68
50
5.18
4.00
4.54
86.1
89.0
87.9
0.63
0.68
0.66
81.2
95.6
89.0
10/27/69
AIR OXYGEN
5.07
3.36
4.01
136.6
125.1
130.4
17.4
20.2
18.9
82
67
53
4.19
4.31
4.25
87.7
88.4
88.2
0.59
0.56
0.57
76.0
88.5
82.8
11/3/69
AIR OXYGEN
4.43
2.99
3.52
129.1
124.9
126.8
17.2
19.2
18.3
81
67
53
3.26
3.26
3.26
90.1
91.1
90.7
0.69
0.48
0.55
77.1
86.9
82.4
-------
TABLE 29
PHASE III OPERATION - AIR & OXYGEN SYSTEM PERFORMANCE
Weekly Average of Daily Values
PARAMETER PERIOD
Stage
Power Required 24 Hour i°
for Liquid Mixing Mean 2
in Oxygen 3
System per Stage
as Hp
Power Required 24 Hour Stfge
for Gas Recirculation Mean 2
in Oxygen 3
System Per Stage
as Hp
Overall Power Night
Required for Liquid Day
Mixing as Hp 24 Hour Mean
Overall Power Night
Required for Gas Day
Recirculation as Hp 24 Hour Mean
Overall Power Night
Utilized as Hp/1000 Day
Gal. of Mixed Liquor 24 Hour Mean
Clarifier Overflow Night
Rates as Gal/Ft2/Day Day
24 Hour Mean
9/8/69
AIR OXYGEN
5.7
2.6
3.1
5.2
2.5
2.5
11.4
11.3
11.4
10.2
10.1
10.1
0.133
0.132
0.132
828 804
1050 1265
947 1058
9/15/69
AIR OXYGEN
5.7
2.7
3.1
4.7
2.4
2.6
11.7
11.4
11.5
9.5
9.8
9.7
0.130
0.130
0.130
1043 820
1202 1194
1130 1027
9/22/69
AIR OXYGEN
5.4
2.7
3.4
4.6
1.7
2.4
11.4
11.6
11.5
9.3
8.3
8.8
0.128
0.122
0.125
1011 947
1186 1226
1106 1098
9/29/69
AIR OXYGEN
5.7
2.8
3.3
4.9
2.2
2.6
11.7
11.7
11.7
8.3
10.0
9.6
0.123
0.133
0.131
828 796
1074 1074
963 947
- 93 -
10/6/69
AIR OXYGEN
5.6
2.9
3.7
5.9
2.1
2.6
12.1
12.3
12.2
11.0
10.1
10.5
0.142
0.137
0.140
787 923
971 1218
883 1082
10/13/69
AIR OXYGEN
4.8
2.9
4.0
4.8
3.0
2.6
11.2
12.0
11.6
10.7
10.1
10.4
0.135
0.136
0.135
771 963
1130 1257
963 1122
10/20/69
AIR OXYGEN
5.4
2.9
4.0
6.4
2.8
2.6
12.0
12.6
12.3
11.1
12.4
11.8
0.142
0.154
0.148
891 1098
1106 1226
1003 1170
10/27/69
AIR OXYGEN
4.6
2.9
4.1
6.8
2.5
2.7
11.3
12.0
11.7
11.7
12.1
11.9
0.141
0.148
0.143
883 1218
1218 1377
1067 1305
11/3/69
AIR OXYGEN
4.9
2.9
3.8
7.4
2.5
2.9
11.4
11.7
11.6
12.8
12.8
12.8
0.148
0.151
0.150
955 1440
1369 1504
1178 1472
-------
Table 28. On an overall nine week average basis, power input of 10.6 HP
was required for gas recirculation and 11.7 HP for liquid mixing, a
total system power input average of 22.3 HP. On a unit volume basis, an
average of 0.137 HP/1000 gal. of mixed-liquor was applied to the system.
In Table 30 are listed weekly average values for treatment effect-
iveness with respect to BOD, COD and influent TSS by both the air and
oxygenation systems. On an overall average basis, an influent BOD
concentration of 262 mg/1 was observed for both the air and oxygenation
systems. Overall average BOD removals of 88% and 94% were attained in
the respective treatment systems, corresponding to average effluent BOD
concentrations of 30 mg/1 and 14 mg/1. Unusually high concentrations of
BOD and COD were found in the influent sewage during September and October
associated with correspondingly high concentration of TSS. This increased
organic load appeared to be constituted by winery or canning wastes, perhaps
both. A portion of the influent solids were floating, fibrous material.
Since no primary treatment system existed at the plant, these materials
were fed directly to the aeration systems.
COD concentrations of the influent waste average 578 mg/1 during the
nine week period. Removal efficiencies of 79% and 84% were determined
for the air and oxygenation systems, respectively. Clarifier effluent COD
concentrations averaging 116 mg/1 and 89 mg/1 were determined for the air
and oxygenation systems. The average TSS concentration of influent sewage
was 430 mg/1 of which 94% was removed in the air aeration system and 97%
in the oxygenation treatment system.
The values in Table 31 indicate the weekly average results of total
phosphorus analyses of the influent wastewater and final clarifier effluents
from each of the treatment units. Of an average influent phosphorus
concentration of 19 mg/1 for the nine week operation period, 327o was
removed by the air aerated system and 27% by the oxygenation treatment
system.
- 94 -
-------
TABLE 30
PHASE III OPERATION - AIR & OXYGEN SYSTEM PERFORMANCE
PARAMETER PERIOD
Feed Wastewater Night
BOD,mg/l Day
24 Hour Mean
Clarifier Effluent Night
BOD,mg/l Day
24 Hour Mean
•/„ BOD Removed Night
Day
24 Hour Mean
Feed Wastewater Night
COD,mg/l Day
24 Hour Mean
Clarifier Effluent Night
COD,mg/l Day
24 Hour Mean
I COD Removed Night
Day
24 Hour Mean
Feed Wastewater Night
TSS,mg/l Day
24 Hour Mean
Clarifier Effluent Night
TSS,mg/l Day
24 Hour Mean
7. TSS Removed Night
Day
24 Hour Mean
9/8/69
AIR OXYGEN
169 169
278 278
237 237
33 23
35 21
34 22
80 86
87 92
86 91
301 301
507 507
430 430
120 115
114 102
116 106
60 62
77 80
73 75
130 130
291 291
231 231
29 14
28 13
28 13
78 89
90 96
88 94
9/15/69
AIR OXYGEN
182 182
252 252
221 221
24 17
31 19
28 18
87 91
88 92
87 92
406 406
624 624
521 521
129 116
113 128
120 114
68 72
82 79
77 78
229 229
585 585
453 453
14 12
17 10
15 10
94 95
97 98
97 98
9/22/69
AIR OXYGEN
233 233
260 260
249 249
25 14
27 14
26 11
89 94
90 95
90 95
524 524
576 576
555 555
111 80
93 107
101 96
79 85
84 81
82 83
366 366
387 387
378 378
15 14
16 10
16 12
96 96
96 97
96 97
9/29/69
AIR OXYGEN
256 256
308 308
283 283
36 22
46 17
42 19
86 92
85 94
85 93
494 494
550 550
528 528
126 78
161 64
147 69
74 84
71 88
72 87
439 439
384 384
421 421
23 16
37 17
31 17
95 96
90 96
93 96
- 95 -
10/6/69
AIR OXYGEN
329 329
232 232
270 270
30 8
25 9
27 9
91 98
89 96
90 97
631 631
569 569
583 583
105 76
96 117
99 101
83 88
83 80
83 83
617 617
345 345
453 453
34 11
25 14
30 13
94 98
93 96
93 97
10/13/69
AIR OXYGEN
259 259
331 331
304 304
24 9
28 12
27 11
91 96
91 96
91 96
631 631
705 705
677 677
92 64
100 108
97 91
85 90
86 85
86 87
643 643
546 546
612 612
14 7
22 9
19 8
98 99
96 98
97 99
10/20/69
AIR OXYGEN
282 282
273 273
277 277
24 11
23 10
23 10
91 96
92 96
92 96
810 810
533 533
649 649
104 62
101 83
102 74
87 92
81 84
84 89
425 425
458 458
444 444
14 13
18 12
17 12
97 97
96 97
96 97
10/27/69
AIR OXYGEN
259 259
275 275
269 269
27 14
33 15
30 15
90 94
88 95
89 95
708 708
639 639
667 667
138 63
118 100
126 84
80 91
82 84
81 87
438 438
418 418
429 429
19 13
25 11
23 12
96 97
94 97
95 97
11/3/69
AIR OXYGEN
193 193
289 289
249 249
30 15
37 12
34 14
84 92
87 96
86 94
583 583
595 595
590 590
132 74
138 61
135 67
77 87
77 90
77 89
370 370
502 502
440 440
21 11
29 9
26 10
94 97
94 98
94 98
-------
TABLE 31
PHASE III OPERATION - AIR & OXYGEN SYSTEM PERFORMANCE
PARAMETER PERIOD
Phosphate In Feed Night
Wastewater as Day
mg/1 of P 24 Hour Mean
Phosphate in Night
Clarifier Effluent Day
as mg/1 of P 24 Hour Mean
7. Phosphate Night
Removed Day
24 Hour Mean
Ammonia Nitrogen Night
in Feed Wasteuater Day
as mg/1 N 24 Hour Mean
Ammonia in Clarifier Night
Effluent as Day
mg/1 N 24 Hour Mean
TKN In Feed Night
Waatewater as Day
mg/1 N 24 Hour Mean
TKN of Clarifier Night
Effluent as Day
mg/1 N 24 Hour Mean
NOj Nitrogen in Night
Feed Wastewater Day
as mg/1 N 24 Hour Mean
NO, Nitrogen in Night
Clarifier Effluent Day
as mg/1 N 24 Hour Mean
9/8/69
AIR OXYGEN
10 10
18 18
15 15
a 12
13 14
12 13
-16 -24
30 25
19 13
26 26
23 23
24 24
24 25
20 22
22 23
38 38
38 38
38 38
31 31
27 26
28 28
0.2 0.2
0 0
0.1 0.1
0.1 0.1
0.1 0.1
0.1 0.1
9/15/69
AIR OXYGEN
11 11
23 23
18 18
11 13
12 13
12 13
-4 -24
46 40
34 24
20 20
27 27
24 24
18 25
23 25
21 25
34 34
54 54
47 47
25 30
29 29
27 29
0 0
0 0
0 0
0.1 0.2
0.2 0.2
0.2 0.2
Weekly Average of Daily Values
9722769
AIR OXYGEN
16 16
18 18
17 17
12 15
13 16
12 15
26 7
31 14
29 11
28 28
27 27
28 28
22 25
24 25
24 25
52 52
48 48
49 49
27 31
28 31
28 31
0 0
0 0
0 0
0.1 0.7
0.1 0.5
0.1 0.6
9/29/69
AIR OXYGEN
14 14
20 20
17 17
11 14
13 14
12 14
24 1
35 32
31 21
32 32
30 30
31 31
23 24
23 25
23 24
52 52
50 50
51 51
33 29
35 31
34 30
0 0
0 0
0 0
0.2 1.3
0.3 1.0
0.3 1.1
- 96 -
1 10/6/69
AIR OXYGEN
21 21
20 20
21 21
15 15
14 15
14 15
29 28
30 23
33 27
38 38
28 28
31 31
27 26
21 25
24 25
63 63
58 58
58 58
35 32
27 34
30 33
0 0
0 0
0 0
0.2 0.5
0.6 0.2
0.5 0.3
10A3/69
AIR OXYGEN
28 28
26 26
26 26
14 15
14 15
14 15
50 48
45 43
47 45
36 36
33 33
34 34
27 24
27 24
27 24
70 70
64 64
66 66
33 31
34 32
34 32
0 0
0 0
0 0
0.1 0.6
0.1 0.5
0.1 0.5
10/20/69
AIR OXYGEN
22 22
21 21
22 22
14 14
13 13
13 13
39 37
38 38
38 38
35 35
31 31
33 33
27 26
24 25
26 25
73 73
52 52
61 61
35 34
34 30
34 31
0 0
0 0
0 0
0.1 0.6
0.2 0.7
0.2 0.7
10/27/69
AIR OXYGEN
21 21
21 21
21 21
14 14
15 14
15 14
31 34
31 34
31 34
36 36
41 41
39 39
26 28
28 26
27 27
65 65
54 54
58 58
31 32
34 30
33 31
0 0
0 0
0 0
0.6 1.2
0.3 1.2
0.4 1.2
11/3/69
AIR OXYGEN
16 16
18 18
18 18
12 13
12 11
12 12
24 23
34 41
30 33
27 27
28 28
28 28
20 21
22 19
21 20
47 47
47 47
47 47
27 25
30 20
28 22
0 0
0 0
0 0
0.2 1.4
0.3 1.6
0.3 1.5
-------
In Tables 31 and 32 are weekly average results of analyses for
influent and effluent NH3-N, TKN, N02-N and N03-N. Removals of ammonia
and TKN for each system were essentially equivalent. An overall
average removal efficiency of approximately 3770 was observed in both
instances. The analysis for effluent nitrate nitrogen in both systems
indicates an overall average concentration of 2.0 mg/1. At this limited
level of nitrification,the average N03-N/total N ratio in the clarifier
effluents of 0.07 indicates a. 7% nitrification efficiency in each system.
The settling characteristics of the biomass under aeration in both
air and oxygenation systems are listed in Table 27. On an overall
average basis, the mixed-liquor SVI values for the air and oxygenation
systems were 63 and 49,respectively. Comparative initial settling
velocities are also indicated. As shown, the air aeration system was
operated at an organic loading averaging 129 Ibs. BOD/Day/1000 cf of
mixed-liquor with a food/biomass ratio of 0.841 Ibs. of BOD/lb. MLVSS.
The oxygenation system organic loading averaged 145 Ibs. BOD/Day/1000 cf
of mixed-liquor with an average food/biomass ratio of 0.554 Ibs. BOD/lb.
MLVSS. Also listed on a weekly average basis in Table 27 are the compar-
ative amounts of activated sludge wasted from each system. On an overall
average basis for the nine week test period, 3490 Ibs. of dry solids
(71% volatile solids) were wasted each day from the air aeration system.
At the same time only 600 Ibs. of solids (69% volatile solids) were
wasted from the oxygenation unit. This decreased level of excess solids
production by the oxygenation system is striking when it is considered
that over 5070 of the BOD, COD, and suspended solids influent to the plant
were treated in this system. On an average comparative basis, 0.989 Ibs.
of excess VSS were produced in the air system per Ib. of BOD removed while
in the oxygenation system 0.134 Ibs. of excess VSS were produced per Ib.
of BOD removed. The proposed explanation for this dramatic reduction in
excess solids in the oxygenation unit will be discussed in detail.
In Table III of the Appendix are listed certain weekly analyses of
mixed-liquor supernatant fractions grab-sampled at the same time from each
- 97 -
-------
TABLE 32
PHASE III OPERATION - AIR & OXYGEN SYSTEM PERFORMANCE
PARAMETER PERIOD
NOj Nitrogen In Night
Feed Wastewater Day
as mg/L N 24 Hour Mean
NOj Nitrogen in Night
Clarifier Effluent Day
as mg/t N 24 Hour Mean
Total Nitrogen In Night
Feed Wastewater Day
as mg/1 N 24 Hour Mean
Total Nitrogen In Night
Clarifier Effluent Day
as mg/1 N 24 Hour Mean
% Total Nitrogen Night
Removed Day
24 Hour Mean
N03 - N/Total N Night
In Feed Wastewater Day
24 Hour Mean
N03 - N/Total N Night
in Clarifier Effluent Day
24 Hour Mean
Lbs. Total Nitrogen
Removed per Ib. of
Dry Solids Wasted 24 Hour Mean
9/8/69
AIR OXYGEN
0.1 0.1
0.1 0.1
0.1 0.1
1.7 1.2
1-.4 1.2
1.5 1.2
38 38
38 38
38 38
32 32
28 27
30 29
15 15
26 28
22 24
0 0
0 0
0 0
0.05 0.04
0.05 0.04
0.05 0.04
0.044 0.313
9/15/69
AIR OXYGEN
0.0 0.0
0.1 0.1
0.1 0.1
2.2 2.0
2.4 2.0
2.3 2.0
34 34
55 55
47 47
27 32
32 32
30 32
20 7
42 42
36 32
0 0
0 0
0 0
0.08 0.06
0.08 0.06
0.08 0.06
0.068 0.483
9/22/69
AIR OXYGEN
0.1 0.1
0.1 0.1
0.1 0.1
3.6 2.5
3.3 2.2
3.4 2.3
52 52
48 48
50 50
31 34
32 33
31 34
41 34
34 31
37 32
0 0
0 0
0 0
0.12 0.07
0.11 0.06
0.11 0.07
0.051 0.405
9/29/69
AIR OXYGEN
0.2 0.2
0.1 0.1
0.1 0.1
2.4 3.3
2.8 2.9
2.7 3.0
52 52
50 50
51 51
35 34
38 35
37 35
32 34
25 31
28 32
0 0
0 0
0 0
0.07 0.10
0.08 0.08
0.07 0.09
0.048 0.428
- 98 -
10/6/69
AIR OXYGEN
0.1 0.1
0.1 0.1
0.1 0.1
3.2 2.8
3.9 2.5
3.6 2.7
63 63
58 58
58 58
38 36
31 37
34 36
39 44
46 37
41 38
0 0
0 0
0 0
0.09 0.08
0.14 0.07
0.12 0.07
0.074 0.279
10/13/69
AIR OXYGEN
0.1 0.1
0.1 0.1
0.1 0.1
2.0 1.6
1.8 1.6
1.9 1.6
70 70
64 64
66 66
35 33
36 34
36 34
50 53
44 46
46 49
0 0
0 0
0 0
0.06 0.05
0.05 0.05
0.05 0.05
0.063 0.950
10/20/69
AIR OXYGEN
0.1 0.1
0.1 0.1
0.1 0.1
1.4 1.5
1.4 1.5
1.4 1.5
73 73
52 52
61 61
36 36
35 32
36 34
50 51
32 39
42 45
0 0
0 0
0 0
0.04 0.04
0.04 0.05
0.04 0.05
0.069 0.531
10/27/69
AIR OXYGEN
0.1 0.1
0.1 0.1
0.1 0.1
1.6 2.0
2.1 2.2
1.9 2.1
65 65
54 54
58 58
33 35
36 33
35 34
49 46
33 38
40 42
0 0
0 0
0 0
0.05 0.05
0.06 0.07
0.05 0.06
0.055 0.319
11/3/69
AIR OXYGEN
0.1 0.1
0.1 0.1
0.1 0.1
1.7 2.0
1.4 2.3
1.5 2.2
47 47
47 47
47 47
29 25
31 24
30 25
40 47
34 49
36 48
0 0
0 0
0 0
0.06 0.15
0.05 0.10
0.05 0.12
0.066 0.374
-------
liquid stage of the two areation systems during Phase III operation. These
values are provided to illustrate the effects of the parallel liquid staging
on removal of the organic and inorganic nutirents in the system.
- 99 -
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DISCUSSION
Oxygenation System Equipment Performance and Reliability
The multistage oxygenation system installed at the Batavia Municipal
Treatment Plant has been described earlier in this report. This unit was
the first of its kind to be installed and operated on a full scale basis.
Any discussion of system reliability must, therefore,take into account
the temporary nature of the installation and the flexibility required by
the variable test program for its operation. With this point considered,
it can be stated that the multistage oxygenation unit functioned in a
highly reliable manner during the periods of operation described here.
Maintenance and service for the system components were not excessive and
no major modifications were required after the initial installation. As
has been described elsewhere, minor modifications were necessary to enable
the oxygenation system to function differently under the widely varying
modes of operation in each phase of the planned test program.
In the absence of technicians assigned to the project, the oxygenation
unit was attended and operated by regular treatment plant personnel, except
during the period from 11:00 p.m. to 7:00 a.m. each day when there was no
operator on duty. This illustrates that the multistage unit did not require
unusual attention for reliable operation. Control of feed oxygen gas to
the system was fully automatic as was the control of mixed-liquor dissolved
oxygen concentrations. Attention to the oxygen aeration equipment by plant
operators was necessary only in the event of electrical power failure.
In this event, no special knowledge was required to restart the turbine
drives and gas recirculation blowers. Clarifier operation and sludge
wasting were manually controlled in the normal manner for both the air
and oxygenation systems. Plant operator duties were, therefore, not
- 100 -
-------
unlike those for any conventionally operated air aeration system. No
special changes were made in the basic hydraulic function of the exist-
ing plant other than the minor modifications necessitated for operating
two dissimilar processes in parallel as required by the project plan.
Mixing and gas recirculation energy utilized to operate the system
confirmed energy requirement predictions based on earlier pilot plant
studies. Thus, the expected high oxygen mass transfer efficiencies were
achieved. The mixing energy applied in each system stage, although much
lower than that applied by necessity to a conventional diffused air
system, was wholly adequate for maintaining a homogenous distribution of
mixed-liquor solids and dissolved oxygen. Underwater inspection revealed
no accumulation of rags and other debris on the impeller or rotating
sparger. The homogenous production and distribution of exceedingly fine
bubbles from the gas-liquid contacting units were obtained as expected
from earlier pilot studies.
Underwater inspection of baffles and gas-liquid contacting equipment
during the program and after shutdown of the unit at the conclusion of the
contract period revealed no unusual corrosion or other deterioration of
carbon steel components. No buildup of sediment on the floor of the
oxygenation system stages was observed.
The reliability of the feed oxygen control system in response to
shock loads and diurnal load variations was excellent. This is verified
in the Results by the consistent maintenance of high D.O. concentration at
all times in the mixed-liquor while treatment efficiencies remained
consistently high. The gas tight covers on the oxygenation system stages
presented no difficulty in containing the gas of high oxygen composition
in the system. This would be expected since positive pressure under these
covers never exceeded three inches of water column. As evidenced by visual
examination, bubble entrainment and subsequent gas loss in the effluent
mixed-liquor from the final stage of the oxygenation system was completely
avoided by the use of an overflow weir to the mixed-liquor effluent line.
- 101 -
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This weir also prevented marked changes in liquid level in the multistage
unit. As a result, changes in gas space pressure under the tank covers
resulting from hydraulic surges were negligible.
Realizing that the multistage oxygenation treatment system functions
by utilizing an aeration gas having a high percent oxygen composition
relative to air, it is appropriate to comment on the safety considerations
involved in the operation of the unit. The gas separation industry has
had extensive experience in the design of equipment and evaluation of
materials which may be used with confidence in atmospheres having high
oxygen concentrations. The result of this background technology is evident
in the unattended operation of many on-site oxygen production facilities
throughout the nation. The same background technology has been employed
in the selection of equipment and materials used in the multistage
oxygenation system tested at Batavia. This factor along with the methods
(sealed covers) used to contain the oxygen aerating gas within the system
eliminated a requirement for any unusual precautions. The equipment and
materials within the system do not support combustion under the operating
conditions described. Although not observed during the test work described
here, the possible introduction of low molecular weight hydrocarbons to the
oxygenation system should be considered. In general, only trace quantities
of volatile hydrocarbons may be dissolved in feed wastewater to a domestic
treatment plant because of the extremely low solubility of these materials
in water. As a result of this low solubility, dissolved hydrocarbons may
be stripped from wastewater in normal primary treatment processing in
either the aerated grit removal chamber or in the primary clarifier as the
effluent flows over the weirs. In the more unusual instance (heavy spills),
where floating liquid hydrocarbons might be contained in the feed waste-
water, complete removal in the primary treatment may not be possible. For
this reason, the oxygenation system may be equipped with a hydrocarbon monitor
so that oxygen flow to the unit is automatically terminated before a hazardous
condition occurs.
- 102 -
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Overall Treatment Effectiveness
A detailed listing of operating and performance data obtained in
the experimental evaluation and comparison of the oxygenation treatment
system with conventional air aeration treatment has been given in the
Results. This week by week listing of daily average performance data is
the synthesis of over 100,000 individual observations and analyses. As
such, many conclusions are apparent by direct examination of these data
and require no further interpretation. For this reason, the discussion of
the relative performance characteristics of the oxygenation system will
serve to put certain overall considerations in their proper perspective.
As an aid in reference to the overall conclusions drawn from this work,
a summary contrasting average operating conditions and systems performance
is shown here in Tables 33, 34, 35, and 36.
The operating flexibility designed into the Batavia treatment plant
permitted evaluation and comparison of the oxygenation treatment system
under three distinctly different sets of conditions. The detailed
description of the means used to accomplish each set of conditions has
been described. In Phase I operation, conditions for evaluation of the
oxygenation system were quite conservative in terms of ultimate system
performance capability. Treatment detention times were those of a more
conventionally operated air aerated system while mixed-liquor solids
concentrations (MLSS and MLVSS), food to biomass ratios (Ibs. BOD/day/
Ib. MLVSS) and organic loadings (Ibs. BOD/day/1000 ft3 mixed-liquor) were
not unusual. By comparison, the oxygenation system differed from the
parallel air system in the high aerating gas oxygen partial pressure, low
mixing energy input, consistently high mixed-liquor dissolved oxygen
concentration and staging of the mixed-liquor and aerating gas. The only
difference in operation of the air system from conventional designed
conditions was the rate of aeration, about 3.0 ft3 of air/gal, of waste
treated compared with a design for about 1.8 ft3/gal. Major areas of
difference in the comparison were then aerating gas oxygen composition,
mixed-liquor D.O. sustained, liquid staging and level of energy input to
transfer oxygen.
- 103 -
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TABU 33
COMPARATIVE SUMMARY OF AIR AND
Wastewater Feed Rate (MGD)
Sludge Recycle Rate (MGD)
Recycle Sludge/Wastewater Feed Rate Ratio
Wastewater Temperature (°F)
Mixed-liquor average D.O. Conc.(mg/l)
Clarifier Effluent D.O. Cone, (mg/1)
*Aeration Detention Time (hrs.)
**Nominal Aeration Detention Time (hrs.)
MLSS Concentration (mg/1)
MLVSS Concentration (mg/1)
OXYGENATION TREATMENT
Phase I
Air
System
1.97
0.25
0.13
59
1.5
0.4
3.5
4.0
2440
1740
Recycle Sludge TSS (mg/1) 14,960
Recycle Sludge VSS (mg/1) 9
Recycle Sludge VSS/TSS Ratio
Mixed -liquor Sludge Volume Index
Mixed-liquor Initial Settling Velocity,
(ft/hr)
Final Clarifier Overflow Rate as
gal/ft2/day
,710
0.65
76
7.7
1570
Operation
Oxygenation
System
1.91
0.44
0.24
59
8.7
4.0
3.4
4.1
3060
2210
18,620
11,760
0.63
64
7.2
1520
SYSTEM PERFORMANCE
Phase II Operation
Oxygenation
System
2.53
0.83
0.34
66
9.0
0.7
1.2
1.5
6980
4450
29,560 16
18,180 11
0.62
36
6.5
1010
Phase
Air
System
1.29
0.25
0.21
70
0.8
0
2.6
3.0
3640
2580
,600
,840
0.71
63
7.7
1030
III Operation
Oxygenation
System
1.44
0.60
0.45
70
8.0
4.3
2.0
2.8
6190
4310
18,790
12,720
0.69
49
5.1
1140
* Raw flow plus recycle sludge flow
** Raw wastewater flow only.
-------
TABLE 34
I
t-1
o
I
% BOD Removal
Feed Wastewatt
Clarifier Eff]
% COD Removal
Feed Wastewatt
Clarifier Eff]
t TSS Removal
COMPARATIVE SUMMARY OF AIR AND OXYGENATION
BOD (mg/1)
tent BOD (mg/1)
• COD (mg/1)
lent COD (mg/1)
• TSS (mg/1)
lent TSS (mg/1)
• VSS (mg/1)
lity (J.T.U.)
itio as
Phase
Air
System
159
16
90
352
84
76
221
16
93
152
5.7
0.566
I Operation
Oxygenation
System
159
11
92
352
73
80
221
9
96
152
5.6
0.414
TREATMENT SYSTEMS PERFORMANCE
Phase II Operation
Oxygenation
System
220
23
90
325
97
71
174
19
89
123
9.1
0.790
Phase
Air
System
262
30
88
578
116
79
430
23
94
332
5.7
0.841
III Operation
Oxygenation
System
262
14
94
578
89
84
430
12
97
332
4.4
0.554
Ibs.BOD/Day/lb. MLVSS
Volumetric Organic Loading as
lbs.BOD/day/1000 ft3 mixed-liquor
Lbs. Dry Solids Wasted/Day
Lbs. VSS Wasted per Lb. BOD
Removed
60.0 57.9
3148
1804
0.871 0.482
212.5
2448
0.412
128.9
3494
0.989
144.8
592
0.134
-------
TABU 35
COMPARATIVE SUMMARY OF AIR AND OXYGENATION TREATMENT .SYSTEMS PERFORMANCE
Feed Wastewater Total Phosphate(mg/I )
Clarifier Effluent Total Phosphate (mg/1)
% Total Phosphate Removed
Feed Wastewater NH3-N (mg/1)
Clarifier Effluent NH3-N (mg/1)
Feed Wastewater TKN (mg/1)
Clarifier Effluent TKN (mg/1)
Feed Wastewater N02-N (mg/1)
Clariffer Effluent N02-N(mg/l)
Feed Wastewater N03-N (mg/1)
Clarifier Effluent N03-N (mg/1)
Feed Wastewater Total Nitrogen (mg/1)
Clarifier Effluent Total Nitrogen(mg/l)
7, Total Nitrogen Removed
N03-Nitrogen/Total Nitrogen in Clarifier
Effluent
Lbs. Total Nitrogen Removed per
Lb. Dry Solids Wasted
Phase
Air
System
11
6
44
20
17
34
22
0.2
0.4
0.3
0.6
35
23
35
0.03
I Operation
Oxygenation
System
11
7
39
20
15
34
19
0.2
0.9
0.3
1.6
35
21
37
0.08
Phase II Operation
Oxygenation
System
12
10
12
19
18
33
22
0
0.2
0.1
1.7
34
26
23
0.07
Phase
Air
System
19
13
32
30
24
53
31
0
0.2
0.1
2.2
53
33
36
0.07
III Operation
Oxygenation
System
19
14
27
30
24
53
30
0
0.7
0.1
2.5
53
33
36
0.07
0.066
0.129
0.066
0.060
0.453
-------
TABLE 36.
COMPARATIVE SUMMARY OF AIR AND OXYGENATION TREATMENT SYSTEMS PERFORMANCE
o
I
Ft3 Air Utilized/gal. Sewage Treated
Feed Oxygen Flow Rate (cfm,NTP)
Gas Exhaust Rate from Oxygen System
Final Stage (cfm,NTP)
Oxygen System Exhaust Gas
Composition as % Oxygen
Overall % of Feed Oxygen Utilized
Lbs. Oxygen Utilized/Lb. BOD Consumed
Total Power Required for Liquid
Mixing (HP)
Total Power Required for Gas
Recirculation (HP)
Overall Power Utilized as HP per
1000 Gal. Mixed-liquor
Total Air Blower Power Utilized (HP)
Phase I Operation
Air Oxygenation
System System
2.89
18.3
1.74
46
95.5
0.94
26.0
2.6
0.088
Phase II Operation
Oxygenation
System
31.0
4.04
55
92.7
0.96
11.1
9.2
0.125
Phase III Operation
Air Oxygenation
System System
4.32
19.0
3.22
51
91.4
0.72
11.7
10.6
0.137
141
138.5
-------
In Phase II of the evaluation of the oxygenation unit, one quarter of
the available aeration tank capacity was utilized to treat the entire
wastewater flow influent to the plant. Under these test conditions,
virtually all operating parameters differed significantly from conventional
air aeration practice. As shown in Table 33, aeration detention times
were quite low (1.2 hours) while mixed-liquor suspended solids concentrations
(MLSS - 6980 mg/1 and MLVSS - 4450 mg/1) were higher than practically
feasible in an air aerated system. As a result of the combination of
staging of the high oxygen partial pressure aerating gas and highly efficient
gas-liquid contacting devices, a mixed-liquor D.O. concentration (9.0 mg/1),
unattainable with air as the aerating gas, was maintained consistently.
As was the case in Phase I operation, a highly flocculant and readily
settleable mixed-liquor biomass was formed which permitted an average
recycle sludge solids concentration of nearly 370 (29,560 mg/1). When
manual operation of the clarifier sludge return pumps (air lifts) was
closely monitored, a recycle solids concentration of 4.570 was achieved with
no apparent undesirable effects to the biomass. As a result of the settling
characteristics of the activated sludge, the recycle sludge flow rate as a
percent of wastewater flow was not greater than that employed in conventional
air aerated systems even though the MLSS level was about three times higher.
The food/biomass ratio for this period of operation averaged 0.790 Ibs.
BOD/day/lb. MLVSS. On an aeration tank volume basis, average organic
loadings of 212.5 Ibs. BOD/day/1000 ft3 of mixed-liquor were applied.
In general, this combination of factors characteristic of high rate treat-
ment with oxygenation are not practically or economically achievable with
conventional air aeration.
In Phase III of the evaluation program,the summary data in Table 33
and 34 indicate that the oxygenation unit was operated under conditions
intermediate to the extremes noted in Phase I and II. The three stage
gas-liquid contacting system was operated at an average MLSS concentration
of 6190 mg/1 and mixed-liquor dissolved oxygen concentrations of 8.0 mg/1.
The food/biomass ratio was 0.554 Ibs. BOD/day/lb. MLVSS and the organic
loading was 144.8 Ibs. BOD/day/1000 ft3 mixed-liquor. The oxygenation
system high sludge recycle rate, compared to Phase I and II, and
- 108 -
-------
commensurately lower recycle sludge concentration have been shown earlier
to result from hydraulic limitations of the sludge recycle system which
prevented operation in the preferred mode. In general, the operation of
the oxygenation system in Phase III was also conducted under conditions not
practically feasible for air aeration. Treatment rates were, however,
reduced from those of Phase II since only half of the influent wastewater
was treated. The resulting average aeration detention time was approximately
2.0 hours (inflow + recycle sludge flow) for the test period.
The air aeration system, operated parallel to the oxygenation unit
in Phase III, was controlled somewhat differently from conventional
practice. It was the intent of this comparison to evaluate the oxygenation
system as described in relation to a high rate air aerated system with
comparable liquid staging. Use of staging baffles in only one-half the
aeration tank volume employed in Phase I, permitted operation of an air
system having three liquid stages at an aeration detention time of 2.6 hours.
MLVSS concentrations were increased to accommodate a higher removal rate
and an uneconomically high aeration rate (4.32 ft3/gal. waste treated) was
used to maintain dissolved oxygen concentrations in the mixed-liquor. Under
conditions of a resulting food/biomass ratio of 0.841 Ibs. BOD/day/lb. MLVSS
and an organic loading of 128.9 Ibs. BOD/day/1000 ft3 of mixed-liquor, it was
not generally possible to maintain mixed-liquor D.O. concentrations above
oxygen limiting conditions at MLVSS concentration of > 2600 mg/1.
The data summarized in Tables 34 and 35 illustrate the overall
treatment performance of the oxygenation system under the wide variety of
operating conditions evaluated. Removals of BOD, COD, and influent
suspended solids (TSS) for the oxygenation systems clearly surpass those
obtained in the parallel air aeration system. During two different phases
(II and III) of the evaluation, operating conditions and treatment rates
for the oxygenation system were such that similar operation of conventional
air aerated systems would not be economically or practically feasible. Where
a parallel comparison of oxygenation system performance with the air aeration
system was possible (Phases I and III), it was necessary to use uneconomically
high aeration rates for the air system to approach the performance level
- 109 -
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of the oxygenation unit. Examination of the weekly average performance
data shown in the Results reveals that treatment performance by the
oxygenation unit was consistently high. Removals of BOD, COD and TSS
during the day, the highest organic and hydraulic loading period, did
not differ importantly from removals during the night, the period of
lowest hydraulic and organic loading.
Total phosphate removals by the air and oxygenation treatment
systems did not differ to any great extent where direct comparisons
were made. The phosphate removals shown for Phases I and III of the
evaluation are relatively high for both systems in comparison to those
removal values generally reported for biological secondary treatment.
A possible explanation for this high phosphate removal is the hardness
and alkalinity of the municipal water supply at Batavia, New York.
The U. S. Geological Survey has reported an average alkalinity of 185 mg/1
as CaC03 and an average hardness of 225 mg/1 as CaC03 for finished water
used by the municipality. The total phosphate removal listed for Phase II
of the evaluation may not be valid due to the admission of anaerobic
digestor supernatant to the system in a manner which prevented sampling
with the influent wastewater.
Removals of ammonia and total Kjeldahl nitrogen by the air and
oxygenation systems were equivalent where these comparisons were made in
Phases I and III operation. Overall nitrogen removals for each system
were approximately 36%. The level of nitrification in neither the air nor
oxygenation system was remarkable. Both systems achieved on the average
a 770 degree of nitrification based on the fraction of total effluent nitrogen
as nitrate in various evaluation periods. These values did not exceed 10%
of the effluent ammonia nitrogen content. Essentially no nitrification
was accomplished in the air system during the Phase I evaluation period.
It would seem reasonable to have expected significant nitrification
by the oxygenation system in particular due to the consistently high
dissolved oxygen level maintained in the mixed-liquor throughout the various
test periods. The reason for lack of extensive nitrification in view of
- 110 -
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this consistently high oxygen level and relatively long apparent sludge
age was not quantitatively ascertained. The relatively low temperature
of the feed wastewater (see Table 33) may possibly be implicated,but such
speculation is not factually based. Operating criteria essential to
establishing nitrification in an oxygenation system will be one of the
objectives of future studies.
Further data with respect to nitrogen removals by the air and
oxygenation systems are summarized and compared in Table 35 where average
Ibs. total nitrogen removed/Ib. dry solids wasted are listed for each
phase of operation. As indicated, the air system activated sludge contained
an average of 6.0-6.6% nitrogen (on a dry weight basis) for Phases I and ill test
periods. In Phases I and II operation,the waste activated sludges from the
oxygenation system contained an average of 12.9% and 6.67« nitrogen,
respectively. These values are all within the range of 4%-1470 nitrogen
per dry weight unit of waste activated sludge most frequently reported in
the literature for domestic waste treatment. The Phase III oxygenation
system value of 45.37» of nitrogen per dry weight unit of waste activated
sludge, however, is definitely not an expected or acceptable value.
Possible reasons for this discrepancy are many, but in the present
study may be reasonably limited to two most probable ones, inaccurate
measurement of waste sludge volume or nitrogen loss from the system to the
atmosphere by denitrification. The former reason appears least probable
of the two since oxygen system waste activated sludge volume was recorded
on two different magnetic flow meters in series with the totalizer results
being checked for coincidence. The second reason, denitrification, is more
probable than the first but cannot be ascertained quantitatively. This
question will be resolved in future studies by direct total nitrogen
analysis of the waste activated sludge, a determination not carried out
in the work reported here.
In all phases of the oxygenation system evaluation,the remarkable
physical properties of the activated sludge produced were consistently
apparent. The mixed-liquor settled quite rapidly and compacted well to
yield evaluation period average SVI values as low as 36 during Phase II
- Ill -
-------
operation. Individual SVI values of as low as 20 were reported at
various times throughout the three operational periods. The initial
settling velocities for the oxygenation system mixed-liquor in Phases II
and III are particularly striking in comparison to air system activated
sludge values. These velocities are related to the total suspended solids
content of the mixed-liquor settling sample. Despite the hindrance imposed
by an approximate two-fold higher suspended solids level in the oxygenation
system mixed-liquor, initial settling rates were comparable to those of
the air system activated sludge. The rapidly settling sludge from the
oxygenation system consistently gives a descrete liquid solids interface
during the settling test. These factors, rapid settling and low SVI
values, are the basis for the relatively high recycle sludge solids
concentration observed in all phases of oxygenation system evaluation.
In Phase II operation,an average 3% recycle sludge suspended solids
concentration was possible even with the limitations in clarifier operation
previously discussed. In Phase III operation,an average recycle suspended
solids concentration of approximately 1.9% was observed for the oxygenation
system compared to approximately 1.7% for the air aerated system; however,
the sludge recycle rate of the oxygenation system was more than twice that
of the air aerated system (the reason for this higher rate was pointed out
in the Results). Limited periods of testing in Phase II of the evaluation
indicated that an average recycle sludge suspended solids concentration of
4.0-4.5% may be possible on a sustained basis with careful operation of
the oxygenation system clarifier and recycle pumps. Additional results of
limited vacuum filtration tests during this period showed that waste recycle
sludge could be filtered directly (after floculation with lime and Fed3
conditioner) without additional thickening. The implication of these
observations is that by taking advantage of a low recycle rate, a waste
activated sludge thickener may not be necessary in treatment facilities
using the oxygenation system. Certainly,the demonstrated ability of the
system to yield substantially higher recycle sludge suspended solids con-
centrations and thus sustain high mixed-liquor solids concentrations at low
recycle sludge flow rates is one of the key factors which makes it econ-
omically possible to operate the high rate treatment process evaluated
here. This property of the oxygen aerated activated sludge system
previously observed in pilot scale studies and shown in the full scale
- 112 -
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tests described here has not been previously recognized or reported in
the literature by others.
Determination of Cell Yield and Endogenous Respiration Coefficients
Both Eckenfelder and O'Connor ^ 'and Eckhoff and Jenkins *• •'have
derived expressions for steady state conditions which may be used to
describe the production of excess VSS by an activated sludge treatment
system. As an approximation here,the COD based expression of Eckhoff
and Jenkins may be used with BOD removal as the basis if one assumes
a constant relationship between the rates of BOD and COD removal. A
plot derived from the test data obtained in this study is shown in
Figure 12 whereby the cell dilution rate as Ibs. excess VSS/day/lb.
MLVSS is related to the specific reaction rate as Ibs. BOD removed/day/
Ib. MLVSS. An equation of the linear relationship obtained is of the
form
y •» mx + b
where m = cell yield coefficient as
Ibs. VSS produced per Ib.
BOD removed
and b = endogenous respiration
coefficient as day~l
In the present comparison of air and oxygen aeration, it was useful to
attempt to obtain comparative values for the cell yield and endogenous
respiration coefficients. For such values to be meaningful in the context
of the available literature, BOD removals should have been calculated
on a soluble BOD basis. This was not possible since whole rather than
filtered effluent samples were used for BOD determinations in the work
presented here. However, this constraint was common to both systems and
the values are meaningful on a comparative basis.
Attempting to plot the data directly, as shown in Figure 12, did not
provide useful correlations, probably a result of the extreme unsteady state
conditions in both the air and oxygenation systems. As a result, the relation-
ship shown was obtained in an indirect manner. Both the cell dilution rates
(Ibs. excess VSS/day/lb. MLVSS) and specific reaction velocities (Ibs.BOD'
removed/day/lb. MLVSS) were plotted as a function of a common parameter,
aeration detention time (based on raw wastewater plus recycle flow), as
shown in Figures 13 and 14. A good correlation of specific
- 113 -
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co
I
CO
I
CO
CO
CO
CO
UJ
o
X
LJ
CO
CD
1.0-
0.8-
0.6-
0.4-
0.2-
AIR SYSTEM y = I.38X -0.17
OXYGEN SYSTEM U = I.05X-0.27
AIR
0.4
OXYGEN
0.6
0.8
^r
-0.17-' X LBS. BOD REMOVED/DAY/LB. MLVSS
•0.27-T
FIGURE 12
CORRELATION OF EXCESS VSS FROM
AIR AND OXYGEN SYSTEMS WITH
BOD REMOVAL AND LBS. MLVSS
1.0
- 114 -
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co
1
CO
CO
CO
CO
UJ
CO
CO
LO-
0.8
0.6-
0.4
0.2
AIR SYSTEM
PHASE I OPERATION A
PHASE HI OPERATION Q
OXYGEN SYSTEM
PHASE I OPERATION A
PHASES OPERATION •
0\ O
I 2 3
AERATION DETENTION TIME (HRS)
"
4
FIGURE 13
COMPARATIVE CORRELATION OF EXCESS VSS
AND MLVSS WITH AERATION DETENTION TIME
- 115 -
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CO
CO
3
CD
O
111
O
2
UJ
C£
O
O
CD
CO
CD
1.0
0.8
0.6
0.4
0.2
AIR SYSTEM
PHASE I Q
PHASE HE •
OXYGEN SYSTEM
PHASE I A
PHASE I O
PHASE IT •
1234
AERATION DETENTION TIME (HRS)
OXYGEN
FIGURE 14
COMPARATIVE CORRELATION OF LBS. BOD REMOVED
AND MLVSS WITH AERATION DETENTION TIME
- 116 -
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reaction velocity was obtained as shown in Figure 14 for both the air
and oxygenation systems. Similarly, the correlation of cell dilution
rate to aeration detention time is shown in Figure 13. For probable
reasons to be subsequently discussed, the cell dilution rates for Phase III
operating data from the oxygenation system did not correlate and were,
by necessity, excluded. Using values obtained for comparable aeration
detention times from the lines drawn in Figures 13 and 14, it was possible to
construct the relationship shown in Figure 12 relating cell dilution rates
to specific reaction velocities with respect to BOD. The equations of
the two lines constructed in Figure 12 are shown where
for th. .ir system - 1.38
The cell yield coefficients obtained in each case clearly indicate
by comparison relative differences in excess volatile solids production
which are expected when one views the sludge production values shown in
Table 34 for the air and oxygenation treatment systems. The air system
produced substantially more VSS per day than did the oxygenation system,
particularly at the relatively high rate treatment conditions in Phase III.
Also, the apparent endogenous respiration coefficients shown here are
nearly two- fold greater in the case of the oxygenation system activated
sludge than in the case of the air aeration system.
The apparent yield coefficients and endogenous respiration coefficients
obtained for both the air and oxygen systems appear consistent with the
results in all but one instance, Phase III oxygenation system operation.
In this period of the evaluation program, approximately seven- fold more
excess volatile solids were produced by the air system than by the oxygena-
tion system even though both systems were operating at nearly the same
volumetric organic loadings. It was for this reason, and the previously
discussed discrepancy in the nitrogen balance of the oxygenation system,
that the Phase III oxygen system cell dilution rate data was not used in
- 117 -
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the correlation shown in Figure 12. The yield and endogenous respiration
coefficients shown from Figure 12 do not reflect, therefore, the extremely
low excess VSS production by the oxygenation system during Phase III
operation.
It is clear from the comparative excess sludge wastage values in
the Results as well as the kinetic evaluation of these data in the fore-
going that the oxygenation system is characterized by the production of
substantially less volatile solids than the parallel air system. The
reasons for this difference may be quite complex and will require further
investigation. One factor of note is the high food/biomass ratio apparent in
the air system, particularly in Phase III operation,coupled with periodic
dissolved oxygen limiting conditions. In this instance,a substantial
portion of BOD may have been wasted from the system in unoxidized form
after immeshment in the bacterial floe (an observation supported by the
odor and appearance of recycle sludge or waste sludge). This would tend
to increase the apparent cell dilution rate and specific reaction velocity
over that obtained where oxygen is not limiting. In Figure 12,the results
of this circumstance would be an increase in the slope of the air system
correlation, a higher yield coefficient, and an increase in the y-axis
intercept, the endogenous respiration coefficient. If this condition were
so, evaluation of the air system operating conditions between the extremes
of Phase I and III might reveal the relationship in Figure 12 to be biphasic.
Obviously,this explanation cannot be tested by the results presented;
however, the synthesis of several observations strongly suggest this
possible reason for the apparent high yield and endogenous respiration
coefficients for the air aeration system.
Another factor of probable importance in reduction of excess volatile
solids production by the oxygenation system is the sustained high MLVSS
concentrations, particularly in Phase II and III, and high dissolved oxygen
concentration. While organic load ings were generally high for the oxygenation
system, the ability to operate at very high MLVSS concentrations yielded
food/biomass ratios generally lower than the air aeration system in both
Phases I and III of the evaluation (see Table 34). Examination of diurnal
- 118 -
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variations in food/biomass ratios in the week by week values in the Results
reveal 3-4 fold differences from day to night. This observation coupled
with increased oxygenation detention times at night indicates the possibility
of extensive auto-oxidation of the biomass at night following an extensive
period of synthesis during the day. Partial confirmation of this occurrence
may be observed in the following sections of the Discussion where day to
night variations in oxygen utilization/lb. BOD removed are shown. If auto-
oxidation of biomass VSS does occur extensively in the various phases of
oxygenation system evaluation, it must result from a daily period of food
limiting conditions. This would suggest the sludge reduction due to endogenous
respiration may in fact be greater than indicated in Figure 12.
A further evaluation of oxygenation system data was done to obtain
values for respiration rates associated with BOD removal and endogenous
activity of the cell mass. According to Eckenfelder and O'Conner , these
values may be obtained from the slope and intercept of a plot correlating
Ibs. oxygen required and Ibs. MLVSS with Ibs. BOD removed and Ibs. MLVSS.
Using oxygenation system data, this relationship is shown in Figure 15 and
reveals that the system requires 0.530 Ibs. oxygen/lb. BOD removed for new
cell synthesis and 0.166 Ibs. oxygen per hour to sustain the endogenous
respiration for each pound of MLVSS under aeration.
Attempts to kinetically evaluate the parallel air and oxygen treatment
systems using the same set of assumptions in each case have posed more
questions than can be answered by this work. For example, the means by
which substantially less inert suspended solids are wasted from the oxygen-
ation system, compared to the air system, even though the same quantity of
inert solids suspended is contained in the common feed wastewater to the
two systems is not known at this time. One possible explanation is that some
fraction of the inert suspended solids entering the oxygenation system are
leaving as inert dissolved solids in the final effluent. This can not be
verified, however, as dissolved solids balances were not carried out for
either system. In part, the unanswered questions are due to the necessarily
limited number of operating conditions evaluated and the experimental program
having been formulated to establish feasibility of oxygenation and
its relative economics. One major factor
- 119 -
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0.7i
CO
CO
m
O
UJ
CO
g
O
§
CO
CD
0.6
0.5-
0.4
0.3
0.2
O.I
= 0.530X + 0.166
O
PHASE I OPERATION
PHASE I OPERATION
PHASE IE OPERATION
O
A
0.2 0.4 0.6 0.8
LBS. BOD REMOVED/DAY/LB. MLVSS
1.0
FIGURE 15
OXYGENATION SYSTEM CORRELATION OF
LBS. OXYGEN CONSUMED/LB. MLVSS WITH
LBS. BOD REMOVED/LB. MLVSS
- 120 -
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which should not be overlooked in the comparison, however, is the
character of the biomass produced by the oxygenation unit. Previous
laboratory and pilot plant studies have indicated that activated sludge
acclimated to high dissolved oxygen concentrations with high aerating
gas oxygen partial pressures may differ distinctly (microbiologically)
from activated sludge developed with air aeration at relatively low
dissolved oxygen concentrations. The ramifications of this observation,
though beyond the scope of the present discussion, are possibly a key
factor in performance differences noted between the air and oxygenation
systems in this work. It is possible that the same set of assumptions
cannot be applied in describing the two systems kinetically.
Relationship of Oxygen Utilized and BOD Consumed to Food/Biomass Ratio
and Oxygenation Detention Time
It has been shown in the Results and Table 33 that substantially
less volatile solids were produced by the oxygenation treatment system
per Ib. of BOD applied than by the air aeration system operated under
nearly identical organic loading conditions in test Phases I and III.
As pointed out in the foregoing Discussion section, a higher apparent
rate of microbial metabolism and lower net rate of excess sludge pro-
duction due to auto-oxidation of the oxygenation system biomass could
explain these differences. In Figure 16 are empirical correlations of
Ibs. oxygen utilized/lb. BOD removed to food/biomass ratio per hour
aeration detention time (includes raw waste + recycle flow). Detention
time is arbitrarily included as a parameter to permit each period of
operation to be distinguished from the others. Night and daytime weekly
average values are shown in each instance. The correlation emphasizes the
3 to 4 fold apparent increase in the amount of oxygen required to remove
equivalent weight units of BOD at night as compared to daytime. Also
emphasized is the difference in food/biomass ratio from day to night
for a given phase of operation. Aeration detention time differences from
day to night have little effect in the observed spread in food/biomass
ratio since detention times are fairly constant for the day and night
periods in a given phase of the test program.
- 121 -
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o
UJ
I
UJ
CC
Q
O
m
Q
UJ
M
UJ
O
S
cri
m
2.0CH
1.75-
1.50-
1.25
1.00
0.75
0.50
0.25
PHASE I OPERATION DAY O
NIGHT A
PHASE H OPERATION DAY •
NIGHT A
PHASE m OPERATION DAY Q
NIGHT •
0.2 0.4 0.6 0.8 1.0
LBS BOD/DAY/LB MLVSS
AERATION DETENTION TIME (HRS)
1.2
FIGURE 16
OXYGENATION SYSTEM CORRELATIONS OF OXYGEN
UTILIZATION/LB BOD REMOVED WITH FOOD/BIOMASS
AND AERATION DETENTION TIME
- 122 -
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Literature sources in general indicate approximately 0.75 Ibs. of
oxygen as necessary for the metabolism of a pound of BOD in domestic
waste treatment using conventional air aeration techniques. This
observation is consistent with the oxygen utilization rate during the
daytime periods of operation in Figure 16 when food/biomass ratios are
highest and aeration detention times are lower relative to night time
operation. During night time operation when food/biomass ratios were
one-fourth as high as daytime, and MLVSS concentrations were approxi-
mately the same, the oxygen utilization rate per Ib. BOD removed was
2.0-2.5 times greater.
The implication of the foregoing observation may be two-fold.
First, it appears that the oxygenation system biomass at high food
loadings during the daytime operation consumed oxygen and BOD for new
cell synthesis through a mechanism not unlike conventional systems even
though the apparent treatment rate was higher in some instances. Secondly,
and most importantly, the oxygen utilization as an apparent function of
BOD removed at night (when food/biomass ratios are low) would indicate
significant endogenous respiration or auto-oxidation of the volatile
solids yield from daytime synthesis. The overall result of this
"partial stabilization process" would be a significant reduction in
overall excess solids production by the oxygenation system, a condition
revealed in the Results. On a comparative basis,this reduction would
be all the more striking where the air system operated in parallel was
subjected to unusually high organic loadings, resulting in a decrease in
Ibs. oxygen available for consumption of BOD.
The foregoing proposed explanation is consistent with the results
contained in this report and most probably is one of the major factors
in the difference in solids production by the two systems. The conclusion
that it is the only factor involved is not warranted by these results.
A practical conclusion warranted by these results, however, is that in
all oxygenation system evaluation phases a substantial reduction in the
amount of sludge produced is apparent in direct comparison to the air
aerated activated sludge system. Therefore, one of the recognized
- 123 -
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advantages of the oxygenation system in domestic waste treatment is a
potential reduction in the amount of waste sludge disposed and thus in
the capital investment for and operating cost of this phase of treatment
plant operation.
Relationship of BOD Removal to Detention Time and MLVSS Concentrations
For purposes of the economic comparison of conventional air aerated
and oxygenation systems, it was convenient to develop a correlation
relating BOD removal to treatment detention time and mixed-liquor volatile
solids concentrations which would be consistent for both systems. Thereby,
a means of developing comparative cost data for equivalent treatment
efficiencies with respect to BOD removal would be provided. The desired
relationship was obtained and is shown in Figure 17. In this plot, weekly
average data for performance of both the air and oxygenation systems is
presented. Percent BOD removed/hour actual treatment detention time/
MLVSS concentration plotted against hours actual treatment detention time x
MLVSS concentration (actual detention time considers both raw waste and
recycle sludge flow) yields a line which is described by the indicated
equation where
% BOD Removal = 31.1
Hours x mg/1 (Hours x mg/1)0*878
% BOD Removal - (31.1) (Hours Actual Detention Time x
mg/1 MLVSS)0'122
This empirical treatment of the data provides a convenient means of
describing the probable combinations of system operating conditions necessary
to achieve equivalent treatment efficiencies (BOD removals) in both the
conventional air and oxygenation systems, providing that oxygen concentrations
are not seriously limiting in either case. A plot of oxygenation system
data alone yields a straight line relationship. The curvilinear form of
the combined data relationship shown, attributed to air system values,
probably is a result of oxygen limiting conditions in this system,particularly
in Phase II of the evaluation. Also,it must be remembered that the air
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CORRELATION OF % BOD REMOVAL
AT BATAVIA WITH ACTUAL DETENTION
PERIOD AND MG/L MLVSS
FIGURE 17
0.020r
o
5
(O
QC
3
O
O
u
a:
0.018
0.016
O
l-
z
iij
g 0.014
o
0.012
0.010
o
o
,0 0.008
PHASE
I
31
HI
OXYGEN
O
3
•
AIR
o
•
31.1
% REMOVAL _
HOURS X MG/L " (HOURS XMG/L)0-878
0.006
5678
HOURS ACTUAL DETENTION X MG/L MLVSS X I0~3
- 125 -
10
-------
system could not be operated at MLVSS concentrations above 2600 mg/1 in
the Phase III evaluation without serious oxygen limitation while operation
of the oxygenation system was possible at nearly two times this MLVSS
concentration. Actual operational limitations then existed for the air
system which were not present for the oxygenation unit. Despite these
considerations, the relationship in Figure 17 provides a valuable,
although approximate tool, for relating the performance of the two systems
in this work.
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AIR AND OKYGENATION SYSTEMS
ECONOMIC COMPARISON
Introduction
The Batavia test data presented here have demonstrated the practical
feasibility of economically operating a high rate, high solids activated
sludge system utilizing oxygen aeration to maintain high dissolved oxygen
levels. The data have substantiated that high treatment quality can be
routinely attained under operating conditions that heretofore would have
been considered impractical and uneconomical.
Observations made have eluded to the potential for cost reduction
and treatment quality improvement inherent in the use of oxygen aeration.
The magnitude of these cost reductions will now be quantitatively evaluated
in detail. This will be accomplished by consideration of the secondary
treatment, sludge disposal, and total plant costs for air and oxygen
aerated activated sludge processes treating municipal wastewater for a
variety of design conditions over a range of plant sizes varying from 1
to 100 MGD. Specifically, new treatment plant facilities will be costed
for each process at four different aeration residence times (and hence
overall BOD removals) for plants of 1, 6, 30, and 100 MGD capacity. It
must be realized, however, that it is practically infeasible to evaluate
all potential modifications and ramifications of each of the two processes.
Nevertheless, it is felt that the following comparison is fairly
respresentative of the relative cost effectiveness of the two processes
for the treatment of typical municipal wastewater. It should be pointed
out, however, that specific unusual situations could significantly alter
the conclusions in either direction relative to the costs presented here.
Of particular note in this repect is the applicability of the oxygenation
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process in upgrading existing activated sludge plants to either increase
capacity and/or improve treatment performance. In these cases the
advantage of the oxygenation process relative to other alternatives will
be significantly greater than in the case of comparative new plant
construction costs presented here.
Of particular note in these comparisons will be the mode of oxygen
supply for the oxygenation systems. An on-site oxygen gas generator will
be costed as an integral part of the overall oxygenation system. Hence,
the cost of supplying oxygen will be evaluated on an amortized capital
investment and operating cost basis just as any other piece of equipment
in the overall wastewater treatment facility. Alternative oxygen supply
methods would include: 1) transport of liquid oxygen to the waste treat-
ment plant for on-site evaporation, and 2) use of a gaseous pipeline supply
if available in the plant vicinity. Separate costs are provided herein
for on-site gas generation plants in order that cost comparisons can be
made for alternative supply methods.
Oxygen generation plants are commercially available from the Linde
Division of Union Carbide Corporation and others. Oxygen gas generation
plants are of a completely automatic type which run unattended except
for infrequent inspection by plant operators.
Basis of Economic Comparison
Bioreactor Design
The relative cost effectiveness of oxygen and air aerated secondary
activated sludge systems were evaluated by considering a range of practical
process design conditions required for each system to accomplish comparable
overall removal levels of BOD and suspended solids. The range of the
primary process design parameters evaluated are summarized in Table 37.
A raw wastewater BOD of 200 mg/1 is assumed in all cases with a 35 percent
removal in the primary clarifiers yielding a primary effluent BOD of
130 mg/1 influent to the activated sludge aeration tanks.
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TABLE 37
BASIC PROCESS DESIGN DATA FOR
AIR AND OXYGENATION SYSTEMS ECONOMIC COMPARISON
Oxygen System
Air System
Raw Wastewater BOD, mg/1
Primary Effluent, BOD, mg/1
Aeration Detention Time,(hr.)
(based on wastewater flow only)
MLSS Concentration, mg/1
MLVSS/MLSS
MLVSS Concentration, mg/1
Recycle Sludge Concentration,mg/1
Mixed-Liquor D.O., mg/1
Aeration Rate (cf NTP)/gallon)
Oxygenation System Absorption
Efficiency (%)
200 200
130 130
1.0,1.33,1.66,2.0 3.0,4.0,5.0,6.0
6800
0.65
4420
40,000
8.0
90-92
2500
0.65
1625
10,000
1.0
0.8, 1.6, 2.4
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The relative economics of secondary treatment with and without
primary clarifiers are not considered a a part of this study. The
results reported here show that raw, prescreened and comminuted sewage
can be directly treated in the secondary aeration tanks with the
attainment of high treatment quality in relatively short aeration
detention times. Due to the predominance of primary clarifiers in
new plant design, however, their use is assumed throughout these
economic comparisons. Further consideration of this parameter will be
undertaken in future work.
The design MLSS concentrations assumed are 2500 mg/1 and 6800 mg/1 for
the air and oxygenation systems respectively with each system having an
MLVSS/MLSS ratio of 0.65. This corresponds to MLVSS concentrations of
1625 mg/1 and 4420 mg/1 in each case. The MLSS are assumed to concentrate
to 10,000 mg/1 and 40,000 mg/1 in the final clarifier underflow, respect-
ively, for the air and oxygenation systems.
Four different aeration residence times (based on raw wastewater flow
only) were evaluated for each system with the constant MLSS and MLVSS
concentration values stated. This corresponds to a range of BOD removals
in the secondary system of approximately 847o to 92% for each system as
summarized in Table 38. The volumetric organic loadings and the food/
biomass ratios for each of the system designs are summarized in Table 39.
As shown,the oxygenation system is designed to operate at volumetric
organic loadings of from 97 to 194 Ibs. BOD/day/1000 ft3 of mixed-liquor
in contrast to values of 32 to 65 for the air system. The food/biomass
ratios, however, are comparable due to the much higher MLVSS concentration
that can be practically and economically maintained in the oxygenation
system.
The basis for these bioreactor design specifications and relative
performance data predictions are based on data obtained during this study
and are shown in Figure 17 wherein the percent BOD removal and MLVSS
concentration is plotted as a function of the aeration residence time and
MLVSS concentrations for both the air and oxygenation treatment systems.
These data have already been discussed. A few comments are in order,
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TABLE 38
SUMMARY OF AERATION RESIDENCE TIMES AND
BOD REMOVALS FOR AIR AND OXYGENATION SYSTEM ECONOMIC COMPARISONS
Air System
Aeration Detention Time-Hrs. Percent BOD Removal
(based on Raw Flow) Secondary System
3.0
4.0
5.0
6.0
84
87
90
92
Oxygen System
Aeration Detention Time-Hrs,
(based on Raw Flow)
1.00
1.33
1.66
2.00
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TABLE 39
SUMMARY OF VOLUMETRIC ORGANIC LOADINGS AND FOOD TO
BIOMASS RATIOS FOR AIR AND OKYGENAIION SYSTEM DESIGNS
Volumetric Organic
Aeration Detention Time- MLVSS Cone. Loading Food to Biomass Ratio
Hrs(based on raw flow) mg/1 (Ibs BOD/Day 1000 ft3) Clb BOD/Day Ib MLVSS)
OXYGENAIION SYSTEM
1.00 4420 194 .70
1.33 4420 146 .53
1.66 4420 117 .42
2.00 4420 97 .35
AIR SYSTEM
3.0 1625 65 .64
4.0 1625 49 .48
5.0 1625 39 .38
6.0 1625 32 .32
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however, regarding the data in Tables 38 and 39, and the effect of the
specific reactor design flow configuration upon the performance data
shown in these tables. By reactor design flow configuration, the
commonly used modifications of the activated sludge process are referred
to. These are the conventional plug flow, step aeration, and completely
mixed reactors. This range of process modification includes the complete
spectrum of reactor hydraulic design configuration from that of a completely
non-mixed (plug flow type) to that of a completely back-mixed, single stage
reactor system having uniform composition throughout. Certainly these
factors have a significant influence on overall system performance and
hence reactor volume to achieve a specified level of overall BOD removal
at a given MLVSS concentration. As is well known, they also significantly
influence the aeration system performance requirements to sustain an
adequate dissolved oxygen level. It is beyond the scope of this study,
however, to evaluate the effect of these various reactor configurations
upon the required system volume. From an overall economic standpoint,
the only factor of any relative significance is the required aeration
tank volume itself. Within the limits of the three to six hour aeration
detention times, shown in Tables 38 and 39 for the air aeration systems,
it is not felt that these various reactor flow modifications are of
significant influence provided that oxygen transfer limitations are not
a factor. Data for completely mixed and step aeration systems show comparable
performance to that of plug flow systems within this range of solids levels
and aeration detention times. Current practice seems to indicate a
preference for step aeration design at an aeration residence time of from
three to four hours to accomplish about 90 percent BOD removal. From an
economic standpoint these designs would be comparable to those projected
here even though the comparative design herein is based on conventional
plug flow operation.
Aeration and Oxygenation System Design
The oxygen requirements for the process designs used were determined
from the respective synthsis and endogenous respiration coefficients
discussed earlier. These coefficients are 0.530 Ibs. oxygen/lb. of BOD
- 133 -
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removed and 0.166 Ibs. oxygen/day per pound of VSS under aeration. The
respective oxygen requirements for the two systems are contained in
Table 40 for the various process design conditions outlined. As shown,
the oxygen requirements are somewhat higher for the oxygen system due
to the higher volatile solids levels under aeration and the higher rate of
oxidation of the volatile solids even though the aeration detention times
are lower.
Certainly many different types of air aeration systems are in use
today in activated sludge plants. Due to the predominance of diffused
air systems in municipal wastewater treatment facilities, however, this
type of air aeration system was chosen as the basis for the economic
comparison. The capital costs and power requirements of these systems
are documented here in sufficient detail so that other types of aeration
equipment could be compared if desired. Considerable care must be
exercised, however, in evaluating capital, operating and maintenance,
and power requirements of alternative aeration systems. Performance must
be evaluated under the actual mixed-liquor aeration conditions experienced
in the activated sludge process which are often quite different
from those normally used in the rating of mechanical aerators.
Furthermore, since the efficiency of diffused air systems as reported
in the literature is widely variant and often confusing regarding the
various claims that are made, a range of air rates and hence oxygen
absorption efficiencies were evaluated in order to ascertain the effect
of this parameter on the relative economic comparison. For this purpose,
air rates of 750, 1500, and 2250 cf(NTP) of air per pound of BOD applied
were evaluated. These air flow rates are equivalent to aeration rates
of 0.8, 1.6, and 2.4 cf(NTP) of air per gallon of sewage for the assumed
process conditions outlined. The air rate of 1500 cf(NTP) per pound of
BOD applied or 1.6 cf(NTP) of air per gallon of sewage would correspond
to the commonly accepted Ten States Standards. Because many claims are
made regarding diffusers of significantly higher efficiency, however, an
air rate of half this amount or 0.8 cf(NTP) per gallon was evaluated.
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TABLE 40
COMPARATIVE OXYGEN SUPPLY AND CONSUMPTION RATES
*Hours
Detention
1.00
1.33
1.66
2.00
1.00
1.33
1.66
2.00
*Hours
Oxygen Supplied and Consumed
Tons 0? Supplied
Day x MGD
0.46
0.51
0.57
0.61
Lb. 0, Supplied
Lb. BOD Removed
1.00
1.08
1.16
1.22
Oxygen Consumed in Air
Tons 0, Consumed
Detention Day x MGD
3
4
5
6
0.39
0.44
0.50
0.55
in Oxygenation System
Tons 0, Consumed
Day x MGD
0.41
0.46
0.51
0.56
Lb. 0, Consumed
Lb. BOD Removed
0.90
0.97
1.05
1.12
Aeration System
Lb. 0, Consumed
Lb. BOD Removed
0.85
0.94
1.02
1.11
Based on Raw Sewage Flow
- 135 -
-------
The blower HP requirements were based on a blower discharge pressure
of 8.1 psig and overall electric power requirements were based on a
compressor efficiency of 70 percent and a motor efficiency of 95 percent.
Similarly, the oxygenation system power requirements were based
on compressor and motor efficiencies of 74 and 95 percent for the gas
recirculation compressors and agitation units.
The power requirements for the two systems are summarized in Tables
41 and 42 for the various process design conditions. The power requirements
for the diffused air system are a function of the assumed air flow
rate, whereas the power requirements of the oxygenation system are a
function of the aeration residence time. This is, of course, a result of
the fact that a considerable portion of the energy is expended in liquid
mixing as opposed to gas compression. Consequently,the oxygenation
system power requirements are a function of the quantity of mixed-liquor
under aeration in addition to the oxygen requirements for BOD removal.
The oxygenation systems in all cases are designed for an overall
utilization efficiency of 90-92 percent in the secondary aeration.
tanks.
The data in Tables 41 and 42 show that a substantial overall power
savings can be realized through the use of the oxygenation system under
all conditions except the extremes of the lowest air rate (0.8 cf(NTP)
per gallon) and the longest residence time for the oxygen system (2 hours).
Under the above conditions power savings of from 15 to 25 percent can be
obtained in the larger plant sizes. At an aeration time of one hour,
power savings of from 33 to 45 percent can be obtained compared to even
the lowest air aeration rate of 0.8 cf(NTP) per gallon. Compared to an
air rate of 1.6 cf(NTP) per gallon, power savings of from 65 to 70 percent
can be obtained with the oxygenation system. In all of these comparisons
it should also be remembered that the oxygenation systems are operating at
dissolved oxygen levels of 8 to 10 mg/1 compared to the nominal air aeration
dissolved oxygen levels of only 1 to 2 mg/1.
- 136 -
-------
TABLE 41
OXYGENATION
MGD *Hours
Treated Detention
1 1.00
1.33
1.66
2.00
6 1.00
1.33
1.66
2.00
30 1.00
1.33
1.66
2.00
100 1.00
1.33
1.66
2.00
SYSTEM POWER
REQUIREMENTS
Oxygen Oxygen
Dissolution Generation
HP HP
6
7
8
10
37
43
50
57
180
210
250
280
510
620
740
870
11
12
14
15
63
70
78
85
300
350
385
420
800
900
1000
1090
Total
Oxygen System
HP
17
19
22
25
100
113
128
142
480
560
635
700
1310
1520
1740
1960
* Based on Raw Sewage Flow
- 137 -
-------
TABLE 42
DIFFUSED AIR AERATION POWER REQUIREMENTS
BLOWER HP REQUIRED
MGD
TREATED
1
6
30
100
0.8 CF (NTP)
OF AIR PER GAL.
OF SEWAGE
25
150
735
2450
1.6 CF (NTP)
OF AIR PER GAL.
OF SEWAGE
50
295
1470
4880
2.4 CF (NTP)
OF AIR PER GAL.
OF SEWAGE
75
440
2200
7350
- 138 -
-------
Primary and Waste Activated Sludge Disposal
As stated earlier, it has been assumed that primary clarifiers are
employed in each of the comparative system designs and that these
clarifiers remove 35 percent of the influent BOD. From a sludge
production standpoint it has been further assumed that the primary
clarifiers in each case produce 600 pounds of VSS per day per MGD treated
and that this primary sludge has a VSS/TSS ratio of 0.7. With respect
to the primary clarifiers and their associated sludge production, therefore,
both the air and oxygenation systems are assumed identical.
The foregoing assumption of equivalency is not the case, however,
with respect to the waste activated sludge produced and its disposal require-
ments. As shown in Table 37, the waste activated sludge or recycle sludge
from the oxygenation system is assumed to have a concentration of 4 percent
suspended solids as compared to that from the air system of 1 percent.
This is a consequence of the considerably higher MLSS concentration (6800 mg.l
compared to 2500 mg/1) carried in the oxygenation system and its enhanced
settling, compacting and dewatering characteristics. It is further assumed,
at 4 percent solids, that the waste activated sludge from the oxygenation
system can be disposed of without prior thickening. In contrast, the
air system waste activated sludge must be thickened prior to further
processing. For purposes of this report, it has been assumed that the
waste activated sludge from the air system would be gravity thickened
from the 1 percent suspended solids level to 4 percent.
For the 1 MGD plant size, it was assumed that sludge disposal for
the combined primary and waste activated sludges would consist of anaerobic
digestion and sludge drying beds. Anaerobic digestion, vacuum filtration,
and cake disposal by landfill was assumed for the 6 MGD plant size. For
the 30 and 100 MGD size plants, it was assumed that the combined primary
and waste activated sludges would be disposed of by anaerobic digestion,
vacuum filtration and incineration.
The excess activated sludge from both systems has been assumed to
have a VSS/TSS ratio of 0.65. The reduction of VSS in the digesters has
been assumed at 50 percent for the primary sludge, 50 percent for the air
- 139 -
-------
system waste activated sludge, and 40 percent for the oxygen system waste
activated sludge. A lower percentage reduction of VSS for the oxygenation
system waste activated sludge was assumed because of the somewhat higher
level of oxidation that it has already undergone in the aeration tanks.
The quantity of excess activated sludge produced from each system was
calculated using the correlation obtained from the data taken during the
course of this study. These data have already been discussed in detail.
The relationships used in each case are as follows:
For the Air System - Lbs excess VSS = 1>3g (lbg> BQD removed/day) .
7 0.174 (Ibs. MLVSS under aeration)
For the Oxygen System - - -f - * 1.05 (Ibs. BOD removed/day) -
3y 0.27 (Ibs. MLVSS under aeration)
Table 43 summarizes the sludge disposal requirements for the air and oxygen
systems for the 100 MGD plant size case for the various process design
parameters. As shown, the amount of waste activated sludge generated in
the oxygen system varies from about 28 to 57 percent of that produced in
the air system for comparable levels of BQD removal. When this is added
to the primary sludge produced in each case this amounts to about a 27
to 42 percent overall reduction in sludge disposal requirements for the
oxygenation system.
- 140 -
-------
TABLE 43
SUMMARY OF SLUDGE DISPOSAL REQUIREMENTS FOR
AIR AND OXYGENATION SYSTEM ECONOMIC COMPARISONS
100 MGD PLANT
Aeration Detention
Time, hrs.
(Based on Raw Flow)
3.0
4.0
5.0
6.0
MLVSS Cone.
(mg/1)
1625
1625
1625
1625
Lbs. MLVSS
Under Aeration
AIR
169,000
226,000
282,000
339,000
Lbs. BOD
Removed /Day
SYSTEM
150,000
153,000
156,000
158,000
Primary Sludge
Produced
(Ibs./Day)
86,000
86,000
86,000
86,000
OXYGENATION SYSTEM
1.00
1.33
1.66
2.00
4420
4420
4420
4420
154,000
204,000
255,000
308,000
150,000
153,000
156,000
158,000
86,000
86,000
86,000
86,000
Waste Activated
Sludge Produced
(Ibs./Day)
148,000
140,000
131,000
120,000
84,000
68,000
51,000
33,000
Total Sludge
Produced
(Lbs./Day)
234,000
226,000
217,000
206,000
170,000
154,000
137,000
119,000
-------
Capital Construction Costs
Investment costs were estimated for the aeration tanks, return
sludge pumps and piping, secondary clarifiers, blowers and diffusers
(including blower building, piping, and prime movers), the oxygenation
dissolution equipment, and the oxygen supply generation equipment.
Sludge disposal capital costs were not directly evaluated as will be
discussed below. All investment costs except for oxygen supply and
dissolution equipment, and covering of the aeration tanks were deter-
mined from information supplied directly by the FWQA. These costs
reflect average January, 1970 construction costs in all cases. For
specific locations and subsurface conditions, these costs could vary
as much as plus or minus 40%.
Investment and total annual costs for other plant facilities
common to both oxygen and air systems and unaffected by aeration
techniques were supplied directly by the FWQA and are shown in Table 44.
Included in these costs are raw sewage pumping, metering, preliminary
treatment, primary sedimentation, service and administration buildings,
and outside piping and appurtenances.
Figure 18 shows the bare aeration tank construction costs used as
a function of the total aeration tank volume. These costs were used for
both air and oxygenation systems. The additional costs of the aeration
tank covers and staging baffles required for the oxygenation system were
evaluated on the basis of an additional cost of $2.80 per square foot
(6-inch thickness) of tank cover and staging baffle area required.
Concrete construction is assumed for the tank covers and baffles.
Figure 19 shows the final sedimentation tank costs as a. function of
the surface area and tank depth. The final sedimentation basins were
sized on the basis of an overflow rate of 800 GPD/ft2 for both the air
and oxygen systems. The basin depth used for the oxygen system was 11
feet as opposed to 10 feet for the air system. The slightly greater
depth for the oxygen system was used to account for the greater concentration
- 142 -
-------
TABLE 44
COSTS FOR COMMON PLANT FACILITIES
Plant Size - MGD 1 6 30 100
Investment - $ 190,000 600,000 2,000,000 5,400,000
Annual Investment Costs-$/Yr. 14,200 44,700 149,000 403,000
Annual 0 & M Costs - $/Yr. 12,300 34,200 110,000 302,000
Total Annual Costs - $/Yr. 26,500 78,900 259,000 705,000
Total Annual Costs-«f/1000 Gal. 7.3 3.6 2.4 1.9
- 143 -
-------
CO
o
K
§t
O -I
FIGURE 18
AERATION TANK CONSTRUCTION COSTS
r500
•400
NOTES:
I. COSTS ADJUSTED TO JAN. 1970
2. INCLUDES TANK ONLY
3. INCLUDES 15 % FOR ENGINEERING
AND FISCAL COSTS
4. PIPING AND APPURTENANCES BEYOND
TANK LIMITS ARE NOT INCLUDED.
-200
bz
^ <
ttj (/)
^ =>
< o
-100
L.Q-
0.1
_L
I 10
TOTAL AREATION TANK VOLUME-MILLION GALLONS
- 144 -
100
-------
tn
I
I-'
u.
6
-------
and hence inventory of solids that would exist in the oxygen system
clarifier.
The air supply construction costs are shown in Figure 20 as a
function of the air supply capacity in thousands of cftn. These costs
include the blower building, blowers, prime movers, air piping and
diffusers. These costs also include reserve or backup blower capacity
as outlined in Table 45. Firm capacity is defined as the capacity
with the largest unit out of service.
The secondary sludge recycle pumps and piping costs are shown in
Figure 21 as a function of the sludge recycle pumping capacity in MGD.
These costs include pump building, pumps, piping, motors, and associated
electrical work. Sludge recycle rates are assumed to be 20 and 33 percent
of influent flow for the oxygenation and air systems, respectively. Pumps
are sized for a ratio of maximum to average plant flow of 2.0.
The capital cost estimates for the oxygenation equipment and the
on-site oxygen gas generators are shown directly in the tabulated cost
comparisons to follow. These figures represent installed costs for
installation of the oxygenation equipment on the covered aeration tanks
and the installation of the oxygen gas generators on a clear, level site
in reasonably close proximity to the aeration tanks. These costs include
all stainless steel piping, instrumentation and controls, electrical switch-
gear, motors, and etc. required for complete installation and automatic
operation of the system. Capital costs for the oxygenation equipment and
on-site oxygen gas generators include a one-time paid-up license fee to
the Linde Division of Union Carbide Corporation for proprietary know-how
and/or patent rights for which applications have been made.
The reserve or backup capacity supplied in the oxygen generators
includes a complete spare air compression unit for the 1, 6, and 30 MGD
plant sizes and a 24-hour storage of on-site liquid oxygen for the 100 MGD
plants. In comparison to the reserve capacity supplied in the air blower
- 146 -
-------
TABLE 45
RESERVE AIR BLOWER CAPACITY INCLUDED
IN CONSTRUCTION COSTS OF AIR SUPPLY SYSTEM
Capacity, cfm % Reserve Capacity Total No. of Blowers
To 1,000 100 2
1,000 - 3,000 50-100 2 or 3
3,000 - 30,000 50 3
30,000 - 50,000 33-50 3 or 4
50,000 - 100,000 33 4
100,000 - 200,000 25-33 4 or 5
Over 200,000 20-25 5 or 6
- 147 -
-------
FIGURE 20
AIR SUPPLY CONSTRUCTION COSTS
rlOO
NOTES:
I. COSTS ADJUSTED TO JAN. 1970
2. INCLUDES BLOWER BUILDING, BLOWERS,
PRIME MOVERS, AIR PIPING, AND DIFFUSERS
3. INCLUDES 15% FOR ENGINEERING
AND FISCAL COSTS
100
FIRM AIR SUPPLY CAPACITY - 1,000 CFM
1000
- 148 -
-------
r70
FIGURE 21
SECONDARY SLUDGE RECYCLE CONSTRUCTION COSTS
-60
o
u
2
i- o
-50
s
NOTES:
I. COSTS ADJUSTED TO JAN. 1970
2. INCLUDES PUMP BUILDING, PUMPS, MOTORS,
STARTERS AND WIRING, AND LIQUID PIPING
3. INCLUDES 15% ENGINEERING AND
FISCAL COSTS
-40
i
£
-30
cc
-20
JL
O.I
I K>
FIRM SECONDARY SLUDGE RECYCLE CAPACITY-MOD
100
-------
systems, this corresponds to 100 per reserve air compression capacity for
the 1, 6, and 30 MGD plant sizes and complete liquid back-up for the 100 MGD
plant. The 24-hour liquid storage is sized on the basis that in most
major municipalities, liquid oxygen could easily be supplied at the rate of
50 T/D on 24 hours notice.
All capital construction costs were amortized at a 5.5 percent interest
rate over a period of 25 years. This corresponds to a capital recovery
factor of 0.07455 or an annual amortization rate of 7.455 percent.
Operating and Maintenance Costs
The operating and maintenance costs for the secondary treatment
facilities were obtained from a June, 1968, FWQA report entitled "Unit
Process Operating and Maintenance Costs for Conventional Waste Treatment
Plants", prepared by Mr. C. L. Swanson. The operating and maintenance
costs for the aeration tanks, blowers, and final sedimentation basins of
a concentional air aeration system were calculated from Mr. Swanson1s
correlations using the following relationship for 1970 costs for an
aeration rate of 1.6 cf(NTP) of air per gallon of wastewater treated.
$/yr/MG = 12,200 + 17,700 (1/MG) °'5
where MG = volume of air aeration tanks in millions of gallons
The operating and maintenance costs for the air rates of 0.8 and 2.4 cf(NTP)
of air per gallon were taken to be 0.9 and 1.1 times those above for 1.6
cf(NTP) per gallon. Of these costs it was assumed that about half was
associated with the blowers and the final clarifiers and the other half
was associated with the aeration tanks and diffusers. On this basis, it
was decided that the operating and maintenance costs for the oxygenation
system dissolution equipment would be comparable to that for the air
blower system. Consequently, the operating and maintenance costs for the
OKygenation equipment and final clarifiers of the oxygen system were cal-
culated from the following relationship:
$/yr/EMG = (0.5) (12,200 + 17,700 (I/ EMG)°'5 )
- 150 -
-------
where EMG = equivalent air aeration tank volume of oxygenation
system in millions of gallons.
This procedure equates the operating and maintenance costs for the oxygen-
ation equipment and final clarifier of the oxygen system to the blower
equipment and final clarifier of the air system for a given size plant
regardless of the relative system horsepower requirements or aeration
tank sizes.
The operating and maintenance costs for the oxygenation system tanks
were reduced by 25 percent on a per gallon basis because of the absence
of diffusers, pipe headers, and etc. and the associated maintenance thereon.
The operating and maintenance costs for the oxygenation tanks were then
given by the following relationship:
$/yr/MG = (0.375) (12,200 + 17,700 (1/MG) °*5)
where MG = volume of oxygenation tanks in millions of gallons.
The additional maintenance and repair costs associated with the
oxygen generation plants were added to the above costs for the oxygen
system. These costs are shown in Figure 22 as a function of the oxygen
plant capacity in tons per day. These costs are representative of those
incurred in Union Carbide owned oxygen generation facilities of comparable
size and complexity.
Total net costs for oxygen gas generation including investment
amortization (5.5 percent interest at 25 years), power, and maintenance
and repair costs are shown in Figure 23 as a function of the plant
generation capacity. Typical current costs for purchased oxygen gas
from on-site gas generation facilities and purchased liquid oxygen are also
shown for comparison purposes. As shown, the net cost is considerably
lower for the purchased oxygen generation plant over the entire range
of plant sizes. The primary reason for this is the lower cost of capital
- 151 -
-------
to a municipal government (5.5 percent interest rate over a 25 year period)
and the inherently higher production and shipping cost of liquid oxygen.
The on-site oxygen gas generation facility for the 1, 6, and 30 MGD
plants is of a design which has not heretofore been marketed on a broad
scale for oxygen generation. These plants are based on sound, well proven
engineering design principles, however, which have been thoroughly tested
and employed in a variety of gas separation processes for a number of
years. These units have operated automatically and unattended for several
years without requiring any maintenance or repair. The oxygen plant
maintenance and repair costs shown in Figure 22 represent an annual cost
of about two percent of the original capital costs and represent a
conservative estimate of these costs based on many years of operating
experience.
Electric power costs for air aeration, oxygen dissolution, oxygen
generation, and recycle sludge pumping were evaluated on the basis of the
following rate schedule:
Plant Size (MGD) Electric Utility Rate ($/KWH)
1 0.0150
6 0.0118
30 0.00943
100 0.00800
The recycle sludge pump head capacity was taken as the depth of the aeration
tanks plus 14 feet. The sludge pump efficiency was assumed at 80 percent.
The compressor efficiencies assumed for the air blowers and the
oxygenation system gas recirculation compressors were 70 and #•% and all
motor efficiencies were assumed at 95 percent. These various unit
equipment efficiencies were then used with the above power rate schedules
to arrive at the electric utility costs for the two processes at the
various plant sizes.
- 152 -
-------
100,000
QC
<
UJ
I
en
H-
(/)
O
O
cc
(C
FIGURE 22
M ft R COSTS FOR OXYGEN GAS
GENERATION PLANTS
JO.OOO
1,000 | I I i I
1 1
I
1 1
1 1
1 1 1
1 1 1 1 ]
O.I
10
TONS OF OXYGEN PRODUCED PER DAY
- 1S3 -
100
-------
120
100
\
»
80
UJ
y 60
-------
Sludge Disposal Costs
As stated previously, sludge disposal for the 1 MGD plant size was
assumed to be by anaerobic digestion and sludge drying beds while that for
the 6 MGD plant was assumed to be by anaerobic digestion, vacuum filtration,
and cake disposal by land fill. Sludge disposal for the 30 and 100 MGD plant
sizes was assumed to be anaerobic digestion, vacuum filtration, and
incineration. In addition, gravity thickening is required for the air
system waste activated sludge regardless of the assumed subsequent disposal
methods. Primary sludge and oxygen system waste activated sludge are not
assumed to require thickening. Costs associated with these disposal methods
also were supplied by the FWQA as total system costs including amortization
and operating and maintenance costs. Amortization costs were calculated at
5.5 percent for 25 years and all capital costs were adjusted to January, 1970,
conditions.
The anaerobic digestion and sludge thickening costs are shown in Figure 24
as a function of the quantity of undigested sludge to be processed. Costs
for vacuum filtration, incineration, sludge drying beds and cake disposal by
land fill are shown in Figure 25 as a function of the quantity of digested
sludge to be processed.
Discussion of Economic Comparison
Detailed cost comparisons are contained in Tables 46 through 61 wherein
the investment, operating and sludge disposal costs are evaluated for each
of four plant sizes and all of the process conditions outlined previously
for both the air and oxygen systems. Also included in these cost comparisons
are the annual costs associated with facilities not related to secondary
treatment and, therefore, common to both the air and oxygen systems. Total
annual costs associated with secondary treatment in each case are arrived
at by summing the amortized investment costs at 5.5% and 25 years and the
operating and maintenance costs including power. The addition of the sludge
disposal costs and the annual costs of common facilities provides total
treatment costs. Total treatment system annual costs are then reduced to
cents per thousand gallons treated in each case.
- 155 -
-------
FIGURE 24
COSTS OF SLUDGE HANDLING PROCESSES
r-100
NOTES:
I. COSTS INCLUDE AMORTIZATION,
OPERATION AND MAINTENANCE
2. COSTS ADJUSTED TO JAN. 1970
3. AMORTIZATION- 5-1/2%, 25 YEARS
4. BASED ON QUANTITY OF
UNDIGESTED SLUDGE
z
o
ID
o
o
I
CO
o
o
z
-J
o
UJ
o
o
(O
-IO
10
100
UNDIGESTED SLUDGE-TONS/DAY
-------
1000
FIGURE 25
COSTS OF SLUDGE HANDLING PROCESSES
NOTES:
I. COSTS INCLUDE AMORTIZATION,
OPERATION, AND MAINTENANCE.
2. COSTS ADJUSTED TO JANUARY, 1970
3. AMORTIZATION - 5 «/2 % , 25 YEARS
4. BASED ON QUANTITY OF
DIGESTED SLUDGE.
z
o
100
(0
0)
O
O
ELUTRATION AND
VACUUM FILTRATION
.SLUDGE DRYING BEDS
INCINERATION
UJ
o
o
D
_l
(O
10
TILTER CAKE DISPOSAL
BY LAND FILL
_L I J J
O.I
1 10
DIGESTED SLUDGE - TONS / DAY
100
- 157 -
-------
TABLE 46
ESTIMATED SECONDARY TREATMENT
, SLUDGE DISPOSAL, AND
TOTAL PLANT COSTS WITH OXYGENATION
1 MGD Treated
Hours Detention
Based on Raw Sewage Flow
SECONDARY TREATMENT SYSTEM INVESTMENTS
Oxygenation Tanks
Sludge Return Pumps & Piping
Oxygen Dissolution Equipment
Oxygen Generation Equipment
Final Sedimentation Tanks
Total Secondary Investment
Annual Secondary Investment Cost, ,*/Yi:.
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COST, ,;/YEAR
Oxygen Generation Power
Oxygen Dissolution Power
M & R Costs & Sludge Return Pump Power
Annual Secondary O & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL
COSTS, ,;/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents /1000 gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS, $/YEAR
Anaerobic Digestion
Sludge Drying Bed Disposal
Annual Sludge Disposal Costs
Cents/ 1000 Gallons
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
.-'/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 Gallons
1.00
23,000
30,000
103,000
99,000
41,000
296,000
22,100
1,100
700
8,300
10,100
22,100
10,100
32,200
8.8
5,900
5,200
11,100
3.0
32,200
11,100
26 , 500
69,800
19.1
1.33
26,000
30,000
104,000
101,000
41,000
302,000
22,500
1,300
800
9,300
11,400
22,500
11,400
33,900
9.3
5,600
4,800
10,400
2.8
33,900
10,400
26,500
70.800
19.4
1.66
29,000
30,000
105,000
103,000
41,000
308,000
23,000
1,400
900
10,200
12,500
23,000
12,500
35,500
9.7
5,400
4,400
9,800
2.7
35,500
9,800
26,500
71,800
19.7
2.00
32,000
30,000
106,000
105,000
41,000
314,000
23,400
1,500
1,000
11,200
13,700
23,400
13,700
37,100
10.2
5,200
3,900
9,100
2.5
37,100
9,100
26,500
72,700
19.9
- 158 -
-------
TABLE 47
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH CKYGENATION
6 MGD Treated
Hours Detention
Based on Raw Sewage Flow
SECONDARY TREATMENT SYSTEM INVESTMENT.$
Oxygenation Tanks
Sludge Return Pumps & Piping
Oxygen Dissolution Equipment
Oxygen Generation Equipment
Final Sedimentation Tanks
Total Secondary Investment
Annual Secondary Investment Costs,$/Yr.
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. $/YEAR
Oxygen Generation Power
Oxygen Dissolution Power
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 Gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Anaerobic Digestion
Vacuum Filtration
Cake Disposal by Landfill
Annual Sludge Disposal Costs
Cents/1000 Gallons
TOTAL TREATMENT SYSTEM ANNUAL
COSTS. $/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 Gallons
1.00
62,000
56,000
155,000
200,000
147,000
620,000
46,200
5,100
3,000
21,600
29,700
46,200
29,700
75,900
3.5
19,100
82,500
11,900
113,500
5.2
75,900
113,500
78,900
268,300
12.3
1.33
75,000
56,000
159,000
210,000
147,000
647,000
48,200
5,700
3,500
25,300
34,500
48,200
34,500
82,700
3.8
17,700
76,700
11,100
105,500
4.8
82,700
105,500
78,900
267,100
12.2
1.66
89,000
56,000
167,000
218,000
147,000
677,000
50,500
6,300
4,000
28,900
39,200
50,500
39,200
89,700
4.1
16 , 200
67,700
10,200
94,100
4.3
89,700
94,100
78,900
262,700
12.0
2.00
103,000
56,000
175,000
227,000
147,000
708,000
52,800
6,900
4,600
33,300
44,800
52,800
44,800
97,600
4.5
15,800
60,100
9,000
84,900
3.9
97,600
84,900
78,900
261,400
11.9
- 159 -
-------
TABLE 48
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH OXYGENATION
30 MGD Treated
Hours Detention
Based on Raw Sewage Flow
SECONDARY TREATMENT SYSTEM INVESTMENT^
Oxygenation Tanks
Sludge Return Pumps & Piping
Oxygen Dissolution Equipment
Oxygen Generation Equipment
Final Sedimentation Tanks
Total Secondary Investment
Annual Secondary Investment Cost,$/Yr.
SECONDARY TREATMENT SYSTEM OPERATING
& MAINTENANCE COSTS. $/YEAR
Oxygen Generation Power
Oxygen Dissolution Power
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL
COSTS. $/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 Gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Anaerobic Digestion
Vacuum Filtration
Incineration
Annual Sludge Disposal Costs
Cents/1000 Gallons
TOTAL TREATMENT SYSTEM ANNUAL
COSTS. $/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 Gallons
1.00
215,000
121,000
471,000
595,000
467,000
1,869,000
139,000
19,000
11,000
63,000
93,000
139,000
93,000
232,000
2.1
82,000
334,000
222,000
638,000
5.8
232,000
638,000
259,000
1,129,000
10.3
1.33
274,000
121,000
503,000
635,000
467,000
2,000,000
149,000
22,000
14,000
77,000
113,000
149,000
113,000
262,000
2.4
75,000
305,000
203,000
583,000
5.3
262,000
583,000
259,000
1,104,000
10.1
1.66
337,000
121,000
547,000
670,000
467,000
2,142,000
160,000
25,000
16,000
90,000
131,000
160,000
131,000
291,000
2.7
68,000
273,000
185,000
526,000
4.8
291,000
526,000
259,000
1,076,000
9.8
2.00
394,000
121,000
571,000
705,000
467,000
2,258,000
168,000
27,000
18,000
104,000
149,000
168,000
149,000
317,000
2.9
59,000
238,000
166,000
463,000
4.2
317,000
463,000
259,000
1,039,000
9.5
- 160 -
-------
TABLE 49
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL, AND
TOTAL PLANT COSTS WITH OXYGENATION
100 MGD Treated
Hours Detention
Based on Raw Sewage Flow
SECONDARY TREATMENT SYSTEM INVESTMENT.!
Oxygenation Tanks
Sludge Return Pumps & Piping
Oxygen Dissolution Equipment
Oxygen Generation Equipment
Final Sedimentation Tanks
Total Secondary Investment
Annual Secondary Investment Costs,$/Yr.
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. $/YEAR
Oxygen Generation Power
Oxygen Dissolution Fewer
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL
COSTS. $/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 Gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Anaerobic Digestion
Vacuum Filtration
Incineration
Annual Sludge Disposal Costs
Cents/1000 Gallons
TOTAL TREATMENT SYSTEM ANNUAL
COSTS. £/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 Gallons
1.00
631,000
236,000
1,678,000
1,090,000
1,350,000
4,985,000
372,000
44,000
28,000
170,000
242,000
372,000
242,000
614,000
1.7
244,000
966,000
569,000
1,779,000
4.9
614,000
1,779,000
705,000
3,098,000
8.5
1.33
817,000
236,000
1,753,000
1,150,000
1,350,000
5,306,000
396,000
50,000
34,000
211,000
295,000
396,000
295,000
691,000
1.9
225,000
893,000
523,000
1,640,000
4.5
691,000
1,640,000
705,000
3,036,000
8.3
1.66
1,017,000
236,000
1,835,000
1,210,000
1,350,000
5,648,000
421,000
55,000
41,000
248,000
344,000
421,000
344,000
765,000
2.1
202,000
796,000
476,000
1,474,000
4.0
765,000
1,474,000
705,000
2,944,000
8.1
2.00
1,217,000
236,000
1,978,000
1,280,000
1,350,000
6,061,000
452,000
60,000
48,000
286,000
394,000
452,000
394,000
846,000
2.3
179,000
691,000
419,000
1,289,000
3.5
846,000
1,289,000
705,000
2,840,000
7.8
- 161 -
-------
TABLE 50
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
1 MGD Treated, 0.8 CF(NTP) of Air/Gallon, or 750 CF(NTP) of Air/Lb. BOD
SECONDARY TREATMENT SYSTEM INVESTMENT. $
Hours Detention
Based on Raw Sewage Flow
3.0 4.0 5.0
6.0
Aeration Tanks
Sludge Return Pumps & Piping
Blowers & Diffusers
Final Sedimentation Tanks
Total Secondary Investment
Annual Secondary Investment Cost,$/yr.
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. &/YEAR
Blower Power
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL
COSTS. £/YEAR
35,000 41,000 46,000 52,000
33,000 33,000 33,000 33,000
59,000 59,000 59,000 59,000
38,000 38,000 38,000 38,000
165,000 171,000 176,000 182,000
12,300 12,700 13,100 13,600
2,500
7,200
2,500
8,600
2,500
9,800
2,500
10,900
9,700 11,100 12,300 13,400
Secondary Investment
Secondary O & M
Annual Secondary Treatment Costs
Cents/1000 gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS 4/YEAR
Waste Activated Sludge Thickening
Anaerobic Digestion
Sludge Drying Bed Disposal
Annual Sludge Disposal Costs
Cents/1000 Gallons
12,300 12,700
9,700 11,100
13,100 13,600
12,300 13,400
22,000
6.0
1,900
6,700
6,500
15,100
4.1
23,800
6.5
1,800
6,600
6,300
14,700
4.0
25,400
7.0
1,800
6,400
6,100
14,300
3.9
27,000
7.4
1,700
6,300
5,800
13,800
3.8
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
S/YSAR
Annual Secondary Costs 22,000
Annual Sludge Disposal Costs 15,100
Annual Common Plant Facilities Costs 26,500
Total Plant Annual Costs 63,600
Cents/gallons 17.4
23,800 25,400
14,700 14,300
26,500 26,500
65,000
17.8
66,200
18.1
27,000
13,800
26,500
67,300
18.4
- 162 -
-------
TABLE 51
ESTIMATED SECONDARY TREATMENT, SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
1 MGD Treated, 1.6 CF(NTP) of Air/Gallon or 1500 CF(NTP) of Air/Lb. BOD
SECONDARY TREATMENT SYSTEM INVESTMENT.$
Aeration Tanks
Sludge Return Pumps & Piping
Blowers & Diffusers
Final Sedimentation Tanks
Total Secondary Investment
Annual Secondary Investment Costs,$/Yr.
SECONDARY TREATMENT SYSTEM OPERATING
& MAINTENANCE COSTS. $/YEAR
Blower Power
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL
COSTS. $/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Waste Activated Sludge Thickening
Anaerobic Digestion
Sludge Drying Bed Disposal
Annual Sludge Disposal Costs
Cents/1000 gallons
TOTAL TREATMENT SYSTEM ANNUAL
COSTS, $/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 gallons
Hours Detention
Based on Raw Sewage Flow
3.0
4.0
5.0
6.0
35,000 41,000
33,000 33,000
79,000 79,000
38,000 38,000
46,000 52,000
33,000 33,000
79,000 79,000
38,000 38,000
185,000 191,000 196,000 202,000
13,800 14,200 14,600 15,100
5,100 5,100 5,100 5,100
8,000 9,500 10,800 12,100
13,100 14,600 15,900 17,200
13,800 14,200 14,600 15,100
13,100 14,600 15,900 17,200
26,900 28,800 30,500 32,300
7.4 7.9 8.4 8.8
1,900 1,800
6,700 6,600
6,500 6,300
15,100 14,700
4.1 4.0
26,900 28,800
15,100 14,700
26,500 26,500
68,500 70,000
18.8 19.2
1,800 1,700
6,400 6,300
6,100 5,800
14,300 13,800
3.9 3.8
30,500 32,300
14,300 13,800
26,500 26,500
71,300
19.5
72,600
19.9
- 163 -
-------
TABLE 52
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
1 MGD Treated, 2.4 CF(NTP) of Air/Gallon, or 2250 CF(NTP) of Air/Lb. BOD
Hours Detention
Based on Raw Sewage Flow
3.0
4.0
5.0
6.0
SECONDARY TREATMENT SYSTEM INVESTMENT. $
Aeration Tanks
Sludge Return Pumps & Piping
Blowers & Diffusers
Final Sedimentation Tanks
35,000 41,000 46,000 52,000
33,000 33,000 33,000 33,000
102,000 102,000 102,000 102,000
38,000 38,000 38,000 38,000
Total Secondary Investment 208,000 214,000 219,000 225,000
Annual Secondary Investment Costs,$/Yr. 15,500 16,000 16,300 16,800
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. $/YEAR
Blower Power
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL COSTS
^/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Waste Activated Sludge Thickening
Anaerobic Digestion
Sludge Drying Bed Disposal
Annual Sludge Disposal Costs
Cents/1000 gallons
TOTAL TREATMENT SYSTEM ANNUAL
COSTS. $/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 gallons
7,600 7,600 7,600 7,600
8,800 10,400 11,900 13,300
16,400 18,000 19,500 20,900
15,500
16,400
31,900
8.7
16,000
18,000
34,000
9.3
16,300
19,500
35,800
9.8
16,800
20,900
37,700
10.3
1,900
6,700
6,500
15,100
4.1
1,800
6,600
6,300
14,700
4.0
1,800
6,400
6,100
14,300
3.9
1,700
6,300
5,800
13,800
3.8
- 164 -
31,900
15,100
26,500
73,500
20.1
34,000
14,700
26,500
75,200
20.6
35,800
14,300
26,500
76,600
21.0
37,700
13,800
26,500
78,000
21.4
-------
TABLE 53
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL, AND
TOTAL PLANT COSTS WITH AIR AERATION
6 MGD Treated, 0.8 CF(NTP) of Air/Gallon, or 750 CF(NTP) of Air/Lb. BOD
Hours Detention
Based on Raw Sewage Flow
3.0 4.0 5.0
6.0
SECONDARY TREATMENT SYSTEM INVESTMENT. $
Aeration Tanks
Sludge Return Pumps & Piping
Blowers & Diffusers
Final Sedimentation Tanks
118,000 151,000 181,000 213,000
71,000 71,000 71,000 71,000
161,000 161,000 161,000 161,000
134,000 134,000 134,000 134,000
Total Secondary Investment 484,000 517,000 547,000 579,000
Annual Secondary Investment Costs,$/Yr. 36,100 38,500 40,800 43,200
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS $/YEAR
Blower Power
M & R Costs & Sludge Return Pumps Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS, $/YEAR
Waste Activated Sludge Thickening
Anaerobic Digestion
Vacuum Filtration
Cake Disposal by Landfill
Annual Sludge Disposal Costs
Cents/1000 gallons
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
I/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 gallons
11,900 11,900 11,900 11,900
23,100 28,100 32,600 35,900
35,000 40,000 44,500 47,800
36,100 38,500 40,800 43,200
35,000 40,000 44,500 47,800
71,100
3.2
78,500
3.6
85,300
3.9
91,000
4.2
8,600 8,100 7,700 7,100
25,200 24,500 23,600 22,500
104,000 101,000 97,800 92,800
14,700 14,400 14,000 13,500
152,500 148,000 143,100 135,900
7.0 6.8 6.5 6.2
71,100 78,500 85,300 91,000
152,500 148,000 143,100 135,900
78,900 78,900 78,900 78,900
302,500 305,400 307,300 305,800
13.8 13.9 14.0 14.0
- 165 -
-------
TABLE 54
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
6 MGD Treated, 1.6 CF(NTP) of Air/Gallon, or 1500 CF(NTP) of Air/Lb. BOD
Hours Detention
Based on Raw Sewage Flow
SECONDARY TREATMENT SYSTEM INVESTMENT.j
Aeration Tanks
Sludge Return Pumps & Piping
Blowers & Diffusers
Final Sedimentation Tanks
Total Secondary Investment
Annual Secondary Investment Costs,$/Yr.
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. $/YEAR
Blower Power
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL
COSTS. $/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Waste Activated Sludge Thickening
Anaerobic Digestion
Vacuum Filtration
Cake Disposal by Landfill
Annual Sludge Disposal Costs
Cents/1000 Gallons
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 gallons
3.0
4.0
5.0
6.0
118,000 151,000 181,000 213,000
71,000 71,000 71,000 71,000
257,000 257,000 257,000 257,000
134,000 134,000 134,000 134,000
580,000 613,000 643,000 675,000
43,200 45,700 47,900 50,300
23,800 23,800 23,800 23,800
25,600 31,000 36,200 41,300
49,400 54,800 60,000 65,100
43,200 45,700 47,900 50,300
49,400 54,800 60,000 65,100
92,600 100,500 107,900 115,400
4.2 4.6 4.9 5.3
8,600 8,100
25,200 24,500
104,000 101,000
14,700 14,400
7,700 7,100
23,600 22,500
97,800 92,800
14,000 13,500
152,500 148,000 143,100 135,900
7.0 6.8 6.5 6.2
92,600 100,500 107,900 115,400
152,500 148,000 143,100 135,900
78,900 78,900 78,900 78,900
J24,000 327,400 329,900 330,200
14.8 14.9 15.1 15.1
- 166 -
-------
TABLE 55
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
6 MGD Treated, 2.4 CF(NTP) of Air/Gallon, or 2250 CF(NTP) of Air/Lb. BOD
Hours Detention
Based on Raw Sewage Flow
SECONDARY TREATMENT SYSTEM INVESTMENT^
Aeration Tanks
Sludge Return Pumps & Piping
Blowers & Diffusers
Final Sedimentation Tanks
Total Secondary Investment
Annual Secondary Investment Cost,$/Yr.
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS, $/YEAR
Blower Power
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Waste Activated Sludge Thickening
Anaerobic Digestion
Vacuum Filtration
Cake Disposal by Landfill
Annual Sludge Disposal Costs
Cents/1000 gallons
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 gallons
3.0
4.0
5.0
6.0
118,000 151,000 181,000 213,000
71,000 71,000 71,000 71,000
J40,000 340,000 340,000 340,000
134,000 134,000 134,000 134,000
663,000 696,000 726,000 758,000
49,400 51,900 54,000 56,500
35,700 35,700 35,700 35,700
27,900 34,000 39,600 45,000
63,600 69,700 75,300 80,700
49,400 51,900 54,100 56,500
63,600 69,700 75,300 80,700
113,000 121,600 129,400 137,200
5.1 5.6 5.9 6.3
8,600
25,200
104,000
14,700
8,100
24,500
101,000
14,400
7,700
23,600
97,800
14,000
7,100
22,500
92,800
13,500
152,500 148,000 143,100 135,900
7.0 6.8 6.5 6.2
113,000 121,600 129,400 137,200
152,500 148,000 143,100 135,900
78,90 78,900 78,900 78,900
344,400 348,500 j51,400 35.2,000
15.7 15.9 16.0 16.1
- 167 -
-------
TABLE 56
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
30 MGD Treated, 0.8 CF(NTP) of Air/Gallon, or 750 CF(NTP) of Air/Lb. BOD
Hours Detention
Based on Raw Sewage Flow
SECONDARY TREATMENT SYSTEM INVESTMENT.j
Aeration Tanks
Sludge Return Pumps & Piping
Blowers & Diffusers
Final Sedimentation Tanks
Total Secondary Investment
Annual Secondary Investment Cost,$/Yr.
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. $/YEAR
Blower Power
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL
COSTS. $/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Waste Activated Sludge Thickening
Anaerobic Digestion
Vacuum Filtration
Incineration
Annual Sludge Disposal Costs
Cents/1000 gallons
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 gallons
3.0
4.0
5.0
6.0
488,000 640,000 788,000 945,000
156,000 156,000 156,000 156,000
488,000 488,000 488,000 488,000
424,000 424,000 424,000 424,000
1,556,000 1,708,000 1,856,000 2,013,000
116,000 127,000 138,000 150,000
48,000 48,000 48,000 48,000
76,000 95,000 113,000 131,000
124,000 143,000 161,000 179,000
116,000
124,000
240,000
2.2
35,000
109,000
431,000
275,000
850,000
7.8
240,000
850,000
259,000
127,000
143,000
270,000
2.5
33,000
105,000
415,000
267,000
820,000
7.5
270,000
820,000
259,000
138,000
161,000
299,000
2.7
31,000
101,000
401,000
259,000
792,000
7.2
299,000
792,000
259,000
150,000
179,000
329,000
3.0
29,000
97,000
382,000
247,000
755,000
6.9
329,000
755,000
259,000
1,349,000 1,349,000 1,350,000 1,343,000
12.3 12.3 12.3 12.3
- 168 -
-------
TABLE 57
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
30 MGD Treated, 1.6 CF(NTP) of Air/Gallon, or 1500 CF(NTP) of Alr/lb. BOD
3.0
Hours Detention
Based on Raw Sewage Flow
4.0
5.0
6.0
SECONDARY TREATMENT SYSTEM INVESTMENT.$
Aeration tanks
Sludge Return Pumps & Piping
Blowers & Diffusers
Final Sedimentation Tanks
488,000 640,000 788,000 945,000
156,000 156,000 156,000 156,000
800,000 800,000 800,000 800,000
424,000 424,000 424,000 424,000
Total Secondary Investment 1,868,000 2,020,000 2,168,000 2,325,000
Annual Secondary Investment Costs,$/Yr. 139,000 150,000 162,000 173,000
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. $/YEAR
Blower Power
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL
COSTS. &/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 gallons
TOTAL PRIMARY ft SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Waste Activated Sludge Thickening
Anaerobic Digestion
Vacuum Filtration
Incineration
Annual Sludge Disposal Costs
Cents/1000 gallons
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 gallons
95,000 95,000 95,000 95,000
84,000 105,000 125,000 145,000
179,000 200,000 220,000 240,000
139,000 150,000 162,000 173,000
179,000 200,000 220,000 240,000
318,000 350,000 382,000 413,000
2.9 3.2 3.5 3.8
35,000 33,000 31,000 29,000
109,000 105,000 101,000 97,000
431,000 415,000 401,000 382,000
275,000 267,000 259,000 247,000
850,000 820,000 792,000 755,000
7.8 7.5 7.2 6.9
318,000 350,000 382,000 413,000
850,000 820,000 792,000 755,000
259,000 259,000 259,000 259,000
1,427,000 1,429,000 1,433,000 1,427,000
13.0 13.1 13.1 13.0
- 169 -
-------
TABLE 58
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
30 MGD Treated, 2.4 CF(NTP) of Air/Gallon, or 2250 CF(NTP) of Air/Lb.BOD
Hours Detention
Based on Raw Sewage Flow
3.0
4.0
5.0
6.0
SECONDARY TREATMENT SYSTEM INVESTMENT,S
Aeration Tanks
Sludge Return Pumps & Piping
Blowers & Diffusers
Final Sedimentation tanks
Total Secondary Investment
488,000 640,000 788,000 945,000
156,000 156,000 156,000 156,000
1,050,000 1,050,000 1,050,000 1,050,000
424,000 424,000 424,000 424,000
2,118,000 2,270,000 2,418,000 2,575,000
Annual Secondary Investment Costs,$/Yr. 158,000 169,000 180,000 192,000
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. $/YEAR
Blower Power
M & R Costs & Sludge Return Pump Power
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL
COSTS. c/YEAR
Secondary Investment
Secondary 0 & M
Annual Secondary Treatment Costs
Cents/1000 Gallons
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Waste Activated Sludge Thickening
Anaerobic Digestion
Vacuum Filtration
Incineration
Annual Sludge Disposal Costs
Cents/1000 Gallons
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 Gallons
143,000 143,000 143,000 143,000
92,000 114,000 137,000 159,000
235,000 257,000 280,000 302,000
158,000 169,000 180,000 192,000
235,000 257,000 280,000 302,000
393,000 426,000 460,000 494,000
3.6 3.9 4.2 4.5
35,000 33,000 31,000 29,000
109,000 105,000 101,000 97,000
431,000 415,000 401,000 382,000
275,000 267,000 259,000 247,000
850,000 820,000 792,000 755,000
7.8 7.5 7.2 6.9
393,000 426,000 460,000 494,000
850,000 820,000 792,000 755,000
259,000 259,000 259,000 259,000
1,502,000 1,505,000 1,511,000 1,508,000
13.7 13.7 13.8 13.8
- 170 -
-------
TABLE 59
ESTIMATED SECONDARY TREATMENT.SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
100 MGD Treated, 0.8 CF(NTP) of Air/Gallon, or 750 CF(NTP) of Air/Lb. BOD
Hours Detention
Based on Raw Sewage Flow
3.0 ; 4.0
5.0
6.0
SECONDARY TREATMENT SYSTEM INVESTMENT.
Aeration Tanks
Sludge Return Pumps & Piping
Blowers & Diffusers
Final Sedimentation Tanks
Total Secondary Investment
1,575,000 2,104,000 2,621,000 3,150,000
312,000 312,000 312,000 312,000
1,140,000 1,140,000 1,140,000 1,140,000
1,240,000 1,240,000 1,240,000 1,240,000
4,267,000 4,796,000 5,313,000 5,842,000
Annual Secondary Investment Costs,$/Yr. 318,000 358,000 396,000 436,000
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. $/YEAR
Blower Power 135,000
M & R Costs & Sludge Return Pump Power 205,000
135,000
260,000
135,000
313,000
135,000
366,000
Annual Secondary 0 & M Costs
SECONDARY TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
340,000 395,000 448,000 501,000
Secondary Investment 318,000
Secondary 0 & M 340,000
Annual Secondary Treatment Costs 658,000
Cents/1000 Gallons 1.8
358,000
395,000
396,000
448,000
436,000
501,000
753,000 844,000 937,000
2.1 2.3 2.6
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Waste Activated Sludge Thickening
Anaerobic Digestion
Vacuum Filtration
Incineration
Annual Sludge Disposal Costs
Cents/1000 Gallons
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
Annual Secondary Costs
Annual Sludge Disposal Costs
Annual Common Plant Facilities Costs
Total Plant Annual Costs
Cents/1000 Gallons
99,000 95,000 89,000 83,000
325,000 316,000 304,000 291,000
1,253,000 1,206,000 1,168,000 1,110,000
712,000 691,000 661,000 642,000
2,389,000 2,308,000 2,222,000 2,126,000
6.5 6.3 6.1 5.8
658,000 753,000 844,000 937,000
2,389,000 2,308,000 2,222,000 2,126,000
705,000 705,000 705,000 705,000
3,752,000 3,766,000 3,771,000 3,768,000
10.3 10.3 10.3 10.3
-171-
-------
TABLE 60
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
100 MGD Treated, 1.6 CF(NTP) of Air/Gallon, or 1500 CF(NTP) of Air/lb. BOD
Hours Detention
Based on Raw Sewage Flow
3.0 4.0 5.0 6.0
SECONDARY TREATMENT SYSTEM INVESTMENT^
Aeration Tanks 1,575,000 2,104,000 2,621,000 3,150,000
Sludge Return Pumps & Piping 312,000 312,000 312,000 312,000
Blowers & Diffusers 1,910,000 1,910,000 1,910,000 1,910,000
Final Sedimentation Tanks 1,240,000 1,240,000 1,240,000 1,240,000
Total Secondary Investment 5,037,000 5,566,000 6,083,000 6,612,000
Annual Secondary Investment Cost,$/Yr. 376,000 415,000 453,000 493,000
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. $/YEAR
Blower Power 269,000 269,000 269,000 269,000
M & R Costs & Sludge Return Pump Power 227,000 288,000 347,000 405,000
Annual Secondary 0 & M Costs 496,000 557,000 616,000 674,000
SECONDARY TREATMENT SYSTEM ANNUAL COSTS,
$/YEAR
Secondary Investment 376,000 415,000 453,000 493,000
Secondary 0 & M 496,000 557,000 616,000 674,000
Annual Secondary Treatment Costs 872,000 972,000 1,069,000 1,167,000
Cents/1000 Gallons 2.4 2.7 2.9 3.2
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS $/YEAR
Waste Activated Sludge Thickening 99,000 95,000 89,000 83,000
Anaerobic Digestion 325,000 316,000 304,000 291,000
Vacuum Filtration 1,253,000 1,206,000 1,168,000 1,110,000
Incineration 712,000 691,000 661,000 642,000
Annual Sludge Disposal Costs 2,389,000 2,308,000 2,222,000 2,126,000
Cents/1000 Gallons 6.5 6.3 6.1 5.8
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
Annual Secondary Costs 872,000 972,000 1,069,000 1,167,000
Annual Sludge Disposal Costs 2,389,000 2,308,000 2,222,000 2,126,000
Annual Common Plant Facilities Costs 705,000 705,000 705,000 705,000
Total Plant Annual Costs 3,966,000 3,985,000 3,996,000 3,998,000
Cents/1000 Gallons 10.9 10.9 10.9 11.0
- 172 -
-------
TABLE 61
ESTIMATED SECONDARY TREATMENT. SLUDGE DISPOSAL. AND
TOTAL PLANT COSTS WITH AIR AERATION
100 MGD Treated, 2.4 CF(NTP) of Air/Gallon, or 2250 CF(NTP) of Air/Lb.BOD
Hours Detention
Based on Raw Sewage Flow
3.0 4.0 5.0 6.0
SECONDARY TREATMENT SYSTEM INVESTMENT.$
Aeration Tanks 1,575,000 2,104,000 2,621,000 3,150,000
Sludge Retun Pumps & Piping 312,000 312,000 312,000 312,000
Blowers & Diffusers 2,710,000 2,710,000 2,710,000 2,710,000
Final Sedimentation Tanks 1,240,000 1,240,000 1,240,000 1,240,000
Total Secondary Investment 5,837,000 6,366,000 6,883,000 7,412,000
Annual Secondary Investment Cost,$/Yr. 435,000 475,000 513,000 553,000
SECONDARY TREATMENT SYSTEM OPERATING &
MAINTENANCE COSTS. $/YEAR
Blower Power 404,000 404,000 404,000 404,000
M & R Costs & Sludge Return Pump Power 248,000 315,000 380,000 445,000
Annual Secondary 0 & M Costs 652,000 719,000 784,000 849,000
SECONDARY TREATMENT SYSTEM ANNUAL COSTS,
I/YEAR
Secondary Investment 435,000 475,000 513,000 553,000
Secondary 0 & M 652,000 719,000 784,000 849,000
Annual Secondary Treatment Cost 1,087,000 1,194,000 1,297,000 1,402,000
Cents/1000 Gallons 3.0 3.3 3.6 3.8
TOTAL PRIMARY & SECONDARY SLUDGE
DISPOSAL COSTS. $/YEAR
Waste Activated Sludge Thickening 99,000 95,000 89,000 83,000
Anaerobic Digestion 325,000 316,000 304,000 291,000
Vacuum Filtration 1,253,000 1,206,000 1,168,000 1,110,000
Incineration 712,000 691,000 661,000 642,000
Annual Sludge Disposal Costs 2,389,000 2,308,000 2,222,000 2,126,000
Cents/1000 Gallons 6.5 6.3 6.1 5.8
TOTAL TREATMENT SYSTEM ANNUAL COSTS,
I/YEAR
Annual Secondary Costs 1,087,000 1,194,000 1,297,000 1,402,000
Annual Sludge Disposal Costs 2,389,000 2,308,000 2,222,000 2,126,000
Annual Common Plant Facilities Costs 705,000 705,000 705,000 705,000
Total Plant Annual Costs 4,181,000 4,207,000 4,224,000 4,233,000
Cents/1000 Gallons 11.5 11.5 11.6 11.6
- 173 -
-------
Figures 26 through 29 compare total treatment costs for the oxygen-
ation and aeration systems for each of the four plant sizes as a function
of nominal aeration detention time (raw wastewater flow only) for the
three assumed aeration rates. It is apparent from inspection of these
figures that the oxygenation process offers significant cost reductions
over the range of plant sizes from 6 MGD to 100 MGD when compared with
the air aeration systems.
When compared with the lowest air aeration rate of 0.8 cf(NTP)/gal.
of wastewater treated, the estimated savings in total treatment costs
with oxygenation range from 11-15% at the 6 MGD size to 17-25% at the 100
MGD size. Compared with an air aeration rate of 1.6 cf(NTP)/gal. of
wastewater treated, the oxygenation system offers a savings in total
treatment cost of 17-21% at the 6 MGD size to 22-29% at the 100 MGD size.
At the 1 MGD plant size, the total treatment costs are about equal at an
air aeration rate of 1.6 cf(NTP)/gal. of wastewater treated. For the
1 MGD plant size, the oxygenation system shows 8-107o higher total treat-
ment costs than an air system with an aeration rate of 0.8 cf(NTP)/gal. of
wastewater treated and about 8-107o lower treatment costs at an air aeration
rate of 2.4 cf(NTP)/gal. of wastewater treated.
Another meaningful comparison of the relative cost effectiveness of
the two processes can be gained by consideration of the total treatment
system costs,exclusive of the common plant facilities cost. These common
plant facilities costs would be incurred for most types of secondary
treatment systems and are unaffected by choice of aeration process.
Table 62 compares the combined secondary treatment and sludge disposal costs
only for the oxygenation system and the air system at an air aeration rate
of 1.6 cf(NTP)/gal. of wastewater treated.
As shown in Table 62, the oxygenation system cost estimates indicate
no savings in treatment costs at the 1 MGD plant size. At the 6, 30, and
100 MGD plant sizes, cost reductions of 23-27%, 26-33%, and 27-32%, respect-
ively, are indicated for the oxygenation system. These cost differentials
- 174 -
-------
28
24
o
S 20
o
o
o
I
CO
en
o
o
Z
Ul
1
UJ
o:
16
12
8
FIGURE 26
TOTAL TREATMENT COSTS
1 MGD TREATED
'ITH OXYGENATION
WITH AIR AERATION
CF(NTP) OF AIR PER
GALLON (PER LB. BOD)
2.4 (2250)
1.6 (1500)
0.8 (750)
HOURS DETENTION IN OXYGENATORS
1.0 1.5 2-0
3456
HOURS DETENTION IN AIR AERATORS
- 175 -
-------
32
FIGURE 27
TOTAL TREATMENT COSTS
6 MGD TREATED
28
24
o
§20
WITH AIR AERATION
CF (NTP) OF AIR PER
GALLON (P-ER LB. BOD)
16
o
o
^ 12
i-
ui
QC
I-
* 8
0-
-o-
-0-
-O-
-O 2.4 (2250)
-O 1.6 (1500)
-O 0.8(750)
WITH OXYGENATION
4 —
HOURS DETENTION IN OXYGENATION
1.0 1.5 2.0
3456
HOURS DETENTION IN AIR AERATORS
- 176 -
-------
32
FIGURE 28
TOTAL TREATMENT COSTS
30 MGD TREATED
28
z
o
24
o
o
r 20
I
CO
§"
o
I-
z
Ul
< l2
UJ
<
*- ft
r^ O
WITH AIR AERATION
CF (NTP) OF AIR PER
GALLON (PER LB. BOD)
0-
-0-
-0-
0-
-0-
-O 2.4 (2250)
-0 1.6 (1500)
-O 0.8 (750)
WITH OXYGENATION
HOURS DETENTION IN OXYGENATORS
1.0 1.5 2.0
I
3456
HOURS DETENTION IN AIR AERATORS
- 177 -
-------
16 —
14 —
z
o
o
o
o
o
12
10
o
o
8
LJ
H 6
Ul
a:
FIGURE 29
TOTAL TREATMENT COSTS
100 MGD TREATED
o-
-o-
-o-
•©-
0-
-o-
-O-
WITH AIR AERATION
CF (NTP) OF AIR PER
GALLON (PER LB. BOD)
•O 2.4 (2250)
-0 1.6 (1500)
-O 0.8 (750)
WITH OXYGENATION
HOURS OF DETENTION IN OXYGENATORS
1.0 1.5 2.0
_L
T
T
3456
HOURS OF DETENTION IN AIR AERATORS
- 178 -
-------
TABLE 62
COMPARISON OF COMBINED SECONDARY TREATMENT AND SLUDGE
DISPOSAL COSTS AS CENTS PER THOUSAND GALLONS OF WASTEWATER TREATED
AIR AERATION
Plant Size (MGD)
1
6
30
100
Plant Size (MGD)
1
6
30
100
f(NTP)/gal. of Wastewater Treated
Detention Time (Hrs.)
3.00
11.5
11.2
10.7
8.9
1.00
11.9
8.6
7.9
6.6
4.00
11.9
11.3
10.7
9.0
OXYGENATION
Detention
1.33
12.1
8.6
7.7
6.4
5.00
12.3
10.5
10.7
9.0
Time (Hrs.)
1.66
12.4
8.4
7.5
6.1
6.00
12.6
11.5
10.7
9.0
2.00
12.7
8.3
7.1
5.8
- 179 -
-------
for 6, 30, and 100 MGD plant sizes are the result of reductions in both
the secondary treatment system costs and the sludge disposal costs for
the oxygenation system. Of these cost differentials, about one-third
is attributable to cost reductions in the secondary treatment system
and about two-thirds to cost reductions in sludge disposal. The sludge
disposal cost reductions with oxygenation ate in turn primarily a result
of the reduced quantity of waste activated sludge produced, as illustrated
in the work presented herein. Additional work is, however, planned to
further substantiate the quantity of waste activated sludge produced by
the oxygenation system under various loading conditions with and without
primary treatment. The data used in support of the economic comparisons
here is the most representative data available and is especially meaningful
considering that both the air and the oxygenation systems were evaluated
treating the same influent wastewater.
An additional relative cost factor, not included in the comparison of
Tables 46 through 61, is the potential land cost savings attainable with
the oxygenation system. The substantial reduction in the aeration tankage
requirements realized with the oxygenation system may result in a
40 - 1070 reduction in the land area required for the secondary treatment
system. In many metropolitan treatment facilities, this reduction in
land requirements can appreciably affect the entire secondary treatment
system investment costs. The reduced land requirements can be particularly
important in increasing the capacity and/or treatment effectiveness of an
existing air aerated activated sludge treatment system by conversion to an
oxygenation system. In many cases, the plant capacity can be increased
2-3 fold with no additional aeration tankage required.
Several other features of the oxygenation system are of considerable
importance and are also not reflected in these economic comparisons. These
include the following: 1) Improved control of mixed-liquor dissolved
oxygen concentrations and enhanced capability for responding to wide
variations in oxygen demand, 2) High dissolved oxygen concentrations in the
- 180 -
-------
mixed-liquor and secondary effluent, 3) Elimination of odor problems
because of the small quantity of exhaust gas and the covered aeration
tank design.
The improved control of mixed-liquor dissolved oxygen concentrations
also results in more uniform and consistently high quality effluents. A
simple pressure control system automatically determines the required
oxygen gas feed rate and moderates the oxygen gas production rate to meet
the oxygen demands of the wastewater being treated. Therefore, the oxygen
production power cost, which represents a substantial fraction of the
oxygenation system total power costs, can be optimized at all times. This
is accomplished without the need for direct mixed-liquor dissolved oxygen
measurements, total organic carbon analysis or other suitable measurements
to determine the incoming waste strength.
- 181 -
-------
REFERENCES
1. Okun, D. A., "System of Bio-Precipitation of Organic Matter
from Sewage," Sewage Works Jour., 21:763, 1949.
2. Pirnie, M., Presentation at Twenty-first Annual Meeting
Federation of Sewage Works Assns.; Detroit, Michigan;
October 18-21, 1948.
3. Budd, W. E. and Lambeth, G. F., "High Purity Oxygen in
Biological Sewage Treatment," Sew. & Ind. Wastes, 29:253, 1957.
4. Okun, D. A. and Lynn, W. R., "Preliminary Investigation into
the Effect of Oxygen Tension on Biological Sewage Treatment,"
in Biological Treatment of Sewage and Industrial Wastes: Vol. I,
Aerobic Oxidation, Reinhold Publishing Corp., New York, 1956.
5. Okun, D. A., "Discussion of High Purity Oxygen in Biological
Sewage Treatment," Sew. & Ind. Wastes, 29:253, 1957.
6. Pfeffer, J. T. and McKinney, R. E., "Oxygen Enriched Air for
Biological Waste Treatment," Water and Sewage Works, October, 1965.
7. Carver, C. E., Jr., "Absorption of Oxygen in Bubble Aeration,"
Biological Treatment of Sewage and Industrial Wastes: in Vol. I,
Aerobic Oxidation, Reinhold Publishing Corp., New York, 1956.
8. McWhirter,.J. R., Proceedings of the 20th Purdue Industrial
Waste Conference, 1965.
9. McWhirter, J. R., Proceedings of the 3rd Annual Conference on
Sanitary Engineering, University of Missouri, 1966.
10. Poloncsik, S., Grieves, R. B. and Pipes, W. 0., Jr.,
"Process Optima in Activated Sludge," Proceedings of the 20th
Purdue Industrial Waste Conference, May, 1965.
11. American Public Health Association, Standard Methods for the
Examination of Water and Wastewater, Twelfth Edition 1963-66,
APHA, New York, 1966.
12. Eckenfelder, W. W., and O'Connor, D. J., "Biological Waste
Treatment," Pergamon Press, New York, 1961.
13. Eckhoff, D. W. and Jenkins, D. "Transient Loading Effects in the
Activated Sludge Process," in Advances in Water Pollution Research,
Munich: Journal WPCF, Vol. 2, 1967
14. Eckenfelder, W. W., and O'Connor, D. J., Proceedings of the 9th
Purdue Industrial Waste Conference, 1954.
- 182 -
-------
APPENDIX
- 183 -
-------
TABLE 1
PHASE I OPERATION
Week of Operation
5/12/69
COD
mg/1
BOD
mg/1
Total
Phosphate
rag/1
NH3-N
mg/1
N02-N
mg/1
NO,-N
mg/1
TKN
mg/1
Soutce
«H«^M^^M
Feed Waste
Inlet
Middle
Outlet
Clar.Eff .
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Air
261.0
246.0
101.0
35.0
19.0
9.0
5.0
6.0
23.0
17.0
0.6
0.8
0.0
0.3
33.0
22.0
Oxygen
216.0
267.0
183.0
101.0
27.0
29.0
11.0
7.0
5.0
8.0
6.0
26.0
23.0
6.0
0.2
0.4
0.3
0.9
0.7
0.9
45.0
29.0
25.0
5/19/69
Air Oxygen
57.0 32.0
208.0
41.0 32.0
98.0 98.0
40.0 27.0
12.0
15.0 12.0
9.0 5.0
4.0 4.0
3.0
3.0 3.0
16.0 18.0
8.0
8.0 3.0
0.8 0.9
0.4
0.5 0.5
0.5 0.9
1.2
1.1 1.0
23.0 24.0
14.0
15.0 16.0
5/26/69
Air
351.0
112.0
445.0
180.0
23.0
6.0
8.0
5.0
34.0
27.0
0.0
0.1
0.1
60.0
33.0
Oxygen
387.0
75.0
96.0
445.0
240.0
15.0
11.0
6.0
9.0
6.0
6.0
40.0
27.0
6.0
0.0
0.9
1.2
0.1
1.0
1.4
70.0
33.0
32.0
6/2/69
Air
122.0
77.0
187.0
50.0
19.0
12.0
4.0
3.0
6.0
4.0
0.0
0.0
0.1
0.0
40.0
28.0
Oxygen
84.0
6i.O
59.0
187.0
32.0
15.0
21.0
11.0
3.0
3.0
3.0
5.0
4.0
3.0
0.5
0.7
0.8
1.2
2.0
1.9
45.0
32.0
25.0
6/9/69
Air
214.0
89.0
153.0
80.0
60.0
22.0
5.0
7.0
27.0
15.0
0.0
0.0
0.0
0.0
30.0
18.0
Oxygen
58.0
32.0
52.0
153.0
38.0
24.0
29.0
13.0
8.0
5.0
7.0
35.0
15.0
7.0
0.1
0.9
0.5
0.1
0.5
0.4
39.0
19.0
14.0
6/16/69
Air
94.0
99.0
157.0
53.0
31.0
16.0
6.0
8.0
28.0
19.0
0.0
0.0
0.0
0.0
34.0
25.0
Oxygen
56.0
175.0
72.0
157.0
26.0
12.0
15.0
4.0
7.0
6.0
8.0
32.0
18.0
8.0
0.1
0.9
1.1
0.0
1.6
1.5
37.0
21.0
24.0
- 184 -
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TABLE II
PHASE II OPERATION
Week of Operation
Parameter
COD
mg/1
BOD
mg/1
Total
Phosphate
mg/1
m -N
mg/1
N02-N
mg/1
NOj-N
mg/1
TKN
mg/1
Source
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
7/28/69 8/4/69
Oxygen_ Oxygen
154.0 136.0
171.0 104.0
146.0 123.0
165.0 285.0
90.0 55.0
62.0 43.0
41.0 45.0
29.0 21.0
10.0
9.0
9.0
22.0
22.0
23.0
0.0
0.0
0.0
0.1
0.1
0.1
30.0
32.0
31.0
8/11/69
Oxygen
189.0
203.0
158.0
201.0
55.0
27.0
36.0
7.0
11.0
9.0
9.0
24.0
20.0
19.0
0.0
0.0
0.0
0.0
0.1
0.1
34.0
30.0
28.0
8/18/69
Oxygen
81.0
163.0
133.0
195.0
50.0
72.0
37.0
9.0
8.0
8.0
20.0
20.0
21.0
0.0
0.0
0.0
0.1
0.1
0.1
29.0
26.0
26.0
8/25/69
Oxygen
93.0
137.0
159.0
284.0
63.0
43.0
32.0
29.0
12.0
11.0
11,0
23.0
24.0
24.0
0.1
0.1
0.1
38.0
36.0
35.0
- 185 -
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TABLE III
FEED WASTE. MIXED-LIQUOR SUPERNATANT AMD CLARIFIER EFFLUENT SPECIAL ANALYSIS
Parameter Source
COO
mg/1
BOD
mg/1
Phosphate
mg/1
NHj-N
mg/1
NOj-N
mg/1
NO,-N
mg/1
TKN
tng/1
Feed Watte
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
Feed Waste
Inlet
Middle
Outlet
Clar.Eff.
PHASE III OPERATION
Week of Operation
10/20/69
Air
150.0
149.9
129.0
294.0
91.0
38.0
32.0
29.0
11.0
11.0
10.0
34.0
33.0
32.0
0.1
0.0
0.0
0.1
0.1
0.1
41.0
42.0
39.0
Oxygen
123.0
88.0
83.0
294.0
34.0
24.0
19.0
23.0
14.0
14.0
14.0
37.0
38.0
37.0
0.0
0.0
1.0
0.1
0.1
-0.6
44.0
45.0
45.0
10/27/69
Air
123.0
151.0
105.0
233.0
45.0
43.0
36.0
24.0
15.0
15.0
15.0
42.0
40.0
37.0
0.1
0.0
0.0
0.1
0.1
0.1
54.0
48.0
47.0
Oxygen
87.0
172.0
193.0
233.0
41.0
23.0
27.0
12.0
16.0
16.0
16.0
44.0
44.0
42.0
0.6
0.9
1.1
1.2
1.3
1.4
55.0
54.0
52.0
11/3/69
Air
184.0
248.0
182,0
155.0
150.0
105.0
74.0
29.0
8.0
8.0
8.0
32.0
32.0
30.0
0.0
0.0
0.0
0.1
0.1
0.1
41.0
37.0
37.0
Oxygen
87.0
78.0
112.0
155.0
66.0
50.0
46.0
18.0
9.0
9.0
8.0
30.0
29.0
28.0
1.0
1.3
1.6
0.4
0.8
1.1
38.0
36.0
34.0
9/8/69
Air
213.0
179.0
163.0
111.0
73.0
46.0
10.9
9.0
9.0
31.0
31.0
30.0
0.0
0.0
0.0
0.1
0.1
0.1
39.0
38.0
38.0
Oxygen
139.0
151.0
67.0
38.0
40.0
13.0
12.0
13.0
37.0
38.0
39.0
0.0
0.1
O.I
0.1
0.1
0.2
42.0
41.0
43.0
9/15/69
Air
281.0
190.0
140.0
246.0
97.0
53.0
46.0
28.0
8.0
8.0
8.0
33.0
32.0
31.0
0.0
0.0
0.0
0.1
0.1
0.1
43.0
42.0
41.0
Oxygen
188.0
123.0
120.0
246.0
43.0
29.0
19.0
17.0
12.0
13.0
36.0
35.0
33.0
0.0
0.1
0.1
0.2
0.1
0.1
45.0
42.0
40.0
9/22/69
Air
181.0
212.0
134.0
229.0
168.0
124.0
22.0
13.0
13.0
13.0
33.0
32.0
29.0
0.0
0.0
0.0
0.1
0.1
0.1
48.0
49.0
44.0
Oxygen
118.0
172.0
162.0
229.0
57.0
43.0
42.0
13.0
15.0
14.0
12.0
27.0
31.0
30.0
0.0
0.0
0.0
0.0
0.1
0.0
39.0
47.0
42.0
9/29/69
Air
219.0
146.0
154.0
288.0
173.0
90.0
38.0
10.0
10.0
10.0
35.0
34.0
31.0
0.1
0.0
0.0
0.1
0.1
0.1
48.0
48.0
49.0
Oxygen
142.0
187.0
185.0
288.0
121.0
52.0
41.0
20.0
14.0
14.0
16.0
37.0
35.0
32.0
0.1
0.3
0.6
0.1
0.1
0.1
55.0
47.0
46.0
- 186 -
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