EPA-670/2-75-039
May 1975
Environmental Protection Technology Series
ADVANCED AUTOMATIC CONTROL
STRATEGIES FOR THE ACTIVATED
SLUDGE TREATMENT PROCESS
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
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EPA-670/2-75-039
May 1975
ADVANCED AUTOMATIC CONTROL STRATEGIES FOR THE
ACTIVATED SLUDGE TREATMENT PROCESS
By
Joseph F. Petersack and Richard G. Smith
Systems Control, Inc.
Palo Alto, California 94304
Program Element No. 1BB043
Project Officer
Joseph F. Roesler
Advanced Waste Treatment Research Laboratory
National Environmental Research Center
Cincinnati, Ohio 45268
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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REVIEW NOTICE
The National Environmental Research Center - Cincinnati has re-
viewed this report and approved its publication. Approval does not
signify that the contents necessarily reflect the views and policies
of the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or recom-
mendation for use.
ii
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FOREWORD
Man and his environment must be protected from the adverse effects of
pesticides, radiation, noise, and other forms of pollution, and the
unwise management of solid waste. Efforts to protect the environment
require a focus that recognizes the interplay between the components of
our physical environment - air, water, and land. The National Environ-
mental Research Centers provide this multidisciplinary focus through
programs engaged in
Studies on the effects of environmental contaminants on man
and the biosphere, and
A search for ways to prevent contamination and to recycle
valuable resources.
Several control strategies were evaluated during the course of this
study to demonstrate the benefits of automatic control of wastewater
treatment plants. Improved control of wastewater treatment plants
increases plant reliability and thus reduces environmental contamination.
iii
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ABSTRACT
Results are presented in this report of a demonstration of both the
feasibility and benefits of applying several, advanced, wastewater-
treatment control strategies using a digital computer for data acquisi-
tion with a man in the control loop for control implementation. The
work was conducted in a full-size (35-MGD (0.13-Mm /day) capacity) sec-
ondary treatment plant at Palo Alto, California.
Control strategies were tested for the secondary treatment portion of
the process and they involved regulation of aeration-tank dissolved
oxygen (DO) mixed liquor suspended solids control (MLSS) and food-to-
microorganism ratio (F/M). Two variations of F/M control were evaluated
using, air flow (in one instance) and a direct measurement of sludge
respiration with an on-line respirometer (in the other instance) to esti-
mate food (BOD). An extensive data-collection program was incorporated
which allowed detailed statistical evaluation of each control algorithm
with regard to performance, effluent quality impact, operating costs,
and reliability. Comparison was made with similar data collected during
benchmark manual-operation tests. Overall results indicate that digital
control, using advanced control concepts, is feasible and that demon-
strable improvements in effluent quality can be obtained. Direct
operating-cost savings in the form of an 11% reduction in air usage were
also shown for DO control.
This project was performed by Systems Control, Inc., under contract to
the City of Palo Alto, California. The Environmental Protection Agency
provided funding under grant number R800356 for the project's demonstra-
tion of "Advanced Control Algorithms for the Activated Sludge Process".
In addition, the State of California Water Quality Control Board con-
tributed additional funds to the project.
iv
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CONTENTS
Page
Foreword iii
Abstract iv
List of Figures vi
List of Tables viii
Acknowledgements ix
Sections
I Conclusions 1
II Recommendations 4
III Introduction 6
IV Phases of the Project 12
V Control Algorithm Design 15
VI Experimental Design 34
VII Hardware and Software Implementation ^6
VIII Control Performance of Automated Strategies 59
IX References 89
X Glossary 91
XI Appendices ^3
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FIGURES
No.. Page
1 Schematic Flow Diagram of the Palo Alto Sewage Treatment 8
Plant
2 Sewage Flow Diagram: City of Palo Alto Water Quality 9
Control Plant
3 Process Flowsheet Activated Sludge System 10
(Conventional System)
4 Process Flowsheet Activated Sludge System 11
(Contact Stabilization)
5 Schematic Diagram of Dissolved Oxygen Control System 16
6 Dissolved Oxygen Controller Block Diagram 21
7 Schematic Diagram of the MLSS Control System 24
8 MLSS Controller Block Diagram 25
9 Schematic Diagram of Food-to-Microorganism Ratio Control 28
Systems
10 Air/RAS Controller Block Diagram 29
11 Respirometer/RAS Controller Block Diagram 31
12 TOC/RAS Feedforward-Controller Block Diagram 33
13 Sample Locations 40
14 Suspended Solids Meter Comparisons 48
15 Respirometer Schematic Diagram 50
16 Badger Respirometer Performance 51
17 Schematic Diagram of TOC Analyzer Installation 52
18 Computer Configuration 54
19 DO Controller: Dissolved Oxygen and Air Flow vs. Time 62
vi
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FIGURES (continued)
No. Page
20 Manual Test I: Dissolved Oxygen and Air Flow vs. Time 63
21 Manual Test II: Dissolved Oxygen and Air Flow vs. Time 64
22 Dry Season Tests: Secondary Effluent BOD,. Concentration 68
vs. Log Normal Frequency Distribution
23 Dry Season Tests: Secondary Effluent Suspended Solids 69
Concentration vs. Log Normal Frequency Distribution
24 MLSS Controller: MLSS and RAS vs. Time 72
25 Manual Test I: MLSS and RAS vs. Time 73
26 Air/RAS Controller: Actual and Estimated Food Uptake 75
27 Air/RAS Controller: MLSS and RAS vs. Time 76
28 Manual Test II: MLSS and RAS vs. Time 77
29 Comparison of Manual Automatic Control of F/M over a three 78
day period Comparison
30 Wet Season Test: Secondary Effluent BOD Concentration vs. 80
Log-Normal Frequency Distribution
31 Wet Season Test: Secondary Effluent Suspended Solids 81
Concentration vs. Log-Normal Frequency Distribution
32 Respirometer/RAS Controller: Actual vs. Estimated Food 84
Uptake
33 Respirometer/RAS Controller: MLSS and RAS vs. Time 86
vii
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TABLES
No. Page
1 Sample Analysis Techniques 41
2 Process Data 43
3 Laboratory Data 44
4 Instrument Costs 47
5 Palo Alto Computer Programs 56
6 Computer System Failures 57
7 Typical Computer Costs 58
8 Averages for Operating Variables for a 30-Day Test Period 60
9 Removal Efficiencies over a 30-Day Test Period 66
10 Operating Cost Comparisons for this Study's Six Test Periods 70
11 Aerator Loading for this Study's Six Test Periods 82
viii
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ACKNOWLEDGEMENTS
Project Director for the City of Palo Alto was Mr. R. N. Doty, Super-
intendent of the Regional Water Quality Control Plant where the demon-
stration took place. Mr. Doty and his staff provided invaluable coopera-
tion and guidance throughout the course of the work. Technical monitor
and Project officer for the EPA was Mr. Joseph F. Roesler, and contract
administrator for the California State Water Quality Control Board was
Mr. Kurt Wasserman. Acknowledgments are given to IBM for the loan of a
System/7 computer that was used in the project.
In addition to all of those mentioned above who aided in the execution
of this project, the help of the following is also gratefully ack-
nowledged. Mr. Robert Smith of the Advanced Waste Treatment Laboratory,
U.S.EPA, and Dr. Mel Holland of the California Water Quality Control
Board.
For Systems Control, Inc., the Project Manager was Laszlo Hajdu and the
Project Coordinator was John Meyer. Project support was also provided
by Joseph Petersack, Richard G. Smith, Charles Martin, David Stepner and
Charles Wells.
IX
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SECTION I
CONCLUSIONS
The feasibility and benefits of applying several advanced wastewater
treatment control strategies in an operational wastewater treatment
plant using a digital computer have been demonstrated. The work was
conducted in a full-size (35-MGD (0.13-Mm /day) capacity) secondary
treatment plant at Palo Alto, California. Detailed evaluation of each
control algorithm with regard to effluent quality impact, operating
costs, and plant reliability was made and compared to manual operations.
Overall results indicate digital control, using advanced control concepts,
is technically feasible. Demonstrable improvements in effluent quality
were obtained with the DO control systems. Specific results are sum-
marized below:
Four advanced control algorithms implemented by a man in the loop
approach were tested and compared with manual plant operation. They
were:
Dissolved Oxygen (DO) Control
Mixed Liquor Suspended Solids (MLSS) Control
Food to Mass of Micro-organism (F/M) Control using Air Flow to
infer food and the rate of Returned Activated Sludge (Air/RAS)
F/M Control using a Respiration Rate measurement to infer food
and the rate of Returned Activated Sludge (respirometer/RAS).
A fifth control approach, F/M control based upon TOC loading and rate of
returned activated sludge, was attempted but inadequate continuous TOC
measurements prevented development of the control approach.
The testing covered both wet and dry-season operation with the first two
controllers (and one manual test) in the dry season, and the last two
controllers (and a manual test) in the wet season. Dry season tests
were conducted with the plant in a new contact stabilization configura-
tion, and wet season tests were conducted with the plant in the conven-
tional, fully mixed, aerator configuration.
The DO controller demonstrated excellent regulating capability in main-
taining DO in the aerator at the desired setpoint of 1.0 mg/1. Effluent
quality improvement amounted to approximately 7% relative increase in
overall secondary removal efficiency based on the four "quality variables"
measured - SS, BOD5, TOC, and COD. An 11% reduction in air use was a
major quantifiable operating cost benefit. At Palo Alto, this represent-
ed a power cost saving of approximately $5,300 per year.
MLSS control was an interim algorithm intended for use in cascade con-
trol in other algorithms. Solids levels in the aerators were maintained
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nearly at set point, except during periods of low plant flow where the
lower limit on the RAS pumping caused uncontrolled increases in MLSS.
While the effluent quality during MLSS control decreased slightly com-
pared to the manual control period, the plant in the new contact con-
figuration exhibited a gradual change in sludge settleability and de-
veloped floating material on the final settlers. This change in sludge
character was probably responsible for the slight decrease in plant
performance and prompted the reconversion of the plant back to its
original, completely mixed configuration for the remainder of the con-
trol studies.
The first F/M controller, Air/RAS, with D.O. control, exhibited Improve-
ment in the regulation of the variability of the instantaneous F/M
compared to that observed during conventional manual operation. But,
with the plant operated in the completely mixed configuration, it did
not produce completely effective regulation of the F/M. The plant air
flow rate with the plant under D.O. control, however, provided a satis-
factory indication of plant load changes and correlated well with the
manually determined BOD,, in the primary effluent entering the biological
reactor. Thus improved and reasonable F/M regulation appears feasible
if:
Adequate sludge storage capacity is provided in the RAS system
Limitations on high/low RAS pumping rates are removed by plant
design changes. (A smaller low limit pumping rate would
enable additional sludge storage during periods of low aerator
loadings and low plant flows.)
Secondary effluent efficiency during the 28-day Air/RAS control period
decreased slightly compared to that during operation with analog man in
the loop D.O. control (Manual Test II), but the absolute values of the
secondary effluent and the overall plant removal efficiencies remained
essentially similar. With the plant's solids inventory and RAS limita-
tions and with the short duration of the control test, realistic evalua-
tion of Air/RAS control approach on plant performance was not achieved.
The second F/M controller, the respirometer/RAS control with D.O. con-
trol, also exhibited improved but not complete regulation of the vari-
ability in the instantaneous F/M. The respirometer/RAS controller
produced the most reduction in the diurnal variability of the instantane-
ous F/M observed during the entire study and kept all instantaneous F/M
values below the point of 0.33 gm of BOD^/day/gm of MLVSS. The con-
troller with the process actually exhibiting an average F/M of about
0.15 gm of BOD,./day/gm of MLVSS, however, did not control to the set-
point F/M and exhibited severe lags of up to 4 hours in responding to
process BOD- load changes.
With unusually efficient primary performance during the respirometer/RAS
test period, the % efficiency of the biological secondary process did
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not change significantly. The best overall plant efficiency and the
best absolute effluent quality observed during the entire study occurred
during plant operation with the respirometer/RAS control. The apparent
improvement, however, is probably not related only or perhaps even
chiefly to the application of respirometer/RAS control. During this
control test, changes in plant wasting, at the request of the City of
Palo Alto, increased the solids inventory in the biological process
compared to that during all other operations. The increased inventory
both in the reactor and clarifier produced the significantly lower
average operating F/M. With the low limit on the plant's RAS pumping
rate and with the lags and inaccuracies in the control algorithm, F/M
control to setpoint was impossible. Further work is needed to assess
the relative effects on plant performance of the reduced variability in
the instantaneous F/M and the operation of the plant at a significantly
lower average F/M.
Digital computer reliability, after system software development, was
excellent. Availability (% of operation time) was over 99%.
Instrument reliability was excellent, for the DO meters and the MLSS
meters, with only infrequent calibration checks required. The on-line
respirometer was also reliable, but required a somewhat higher level
of periodic maintenance for cleaning and for chemicals replacement.
The on-line TOG analyzer required extensive calibration and maintenance,
and this analyzer will require additional development to be fully
acceptable in primary effluent service.
Data management functions developed for the demonstration included
automated scanning, logging, and data-base updating. The functions
allowed on-line reports, equipment and alarm summaries, and off-line
data preparation. Additionally, a set of programs was developed to
analyze the data for effective comparative analysis of the various
tests. Additional functions included on-line tuning of algorithms and
monitoring of control-performance.
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SECTION II
RECOMMENDATIONS
In general, while existing instrumentation (except for the TOG control
approach) is sufficiently reliable to implement the advanced control
algorithms that were demonstrated, sensor development should be encour-
aged for on-line monitoring and control.
Specific recommendations are:
1. Develop specifications and design guidelines for closed loop
DO control systems in fully mixed aerators to realize energy
savings and improved effluent quality.
2. Make further explorations using pilot-plant process-
development studies directed toward improving instantaneous
F/M control. Among the areas to investigate are the impact of
separate sludge storage and the results to be expected for
plug-flow reactors.
3. Evaluate the possibilities for, and benefits of, controlling
other plant functions from the computer such as:
Activated sludge wasting
Chlorine dosage
Digester temperature
«
Sludge solids handling
4. Determine optimum methods for computer information display and
operator interfacing to improve monitoring and control of the
plant. More frequent and higher quality data will speed
trouble diagnosis and improve productivity by having the
computer perform the routine data-reporting functions.
5. Continue testing of on-line analytical instrumentation, es-
pecially for the quantities TOC, COD and low-level (less than
50 mg/1) suspended solids. Evaluation should place emphasis
on reliability with minimum maintenance and calibration
requirements.
Less quantifiable, but potentially more significant, operating cost
savings were not addressed in this study, but they should ultimately be
considered when determining the cost/benefit tradeoffs for these control-
lers. Among the areas of definite further savings are:
o Manpower Productivity - More effective manpower utilization is
possible with closed loop automatic control because such
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control relieves operators of time-consuming adjustments of
process-monitoring and control devices.
Incremented Capacity Costs - Improved effluent quality may be
translated into increased plant capacity. This could result
in a delay or reduction in planned expansion of facilities
with a resultant sizeable savings in capital investment costs.
A detailed economic-investment analysis, including estimates of these
and other factors, is necessary before the true net cost of an opera-
tional control system, be it analog or digital, can be ascertained.
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SECTION III
INTRODUCTION
SCOPE AND PURPOSE OF THE DEMONSTRATION PROJECT
The Palo Alto Automation Project demonstrated the feasibility of using
man in the loop digital computer control to implement several advanced
control schemes for the activated sludge process of a wastewater treat-
ment facility. Control algorithm designs were selected to achieve
improvements in waste removal efficiencies as well as reductions in
operating costs. Extensive computerized data collection and analysis
were employed to evaluate each control system for a 30 day experimental
test period. Two 30-day tests were also performed in which conventional
plant operation was employed. The manual control periods provide compar-
ison data for both wet and dry season operation. A three-day intensive,
data-collection period at the end of each 30-day test was used to obtain
information for detailed hour-by-hour evaluation of control system
performance.
Control strategies examined were concerned with the secondary treatment,
or activated sludge portion of the plant. Basically, the various experi-
ments fall into two categories:
1. Control of dissolved oxygen concentration in order to minimize
aeration costs.
2. Control of the ratio of waste utilization to microorganism
concentration (Food to mass, F/M) in an attempt to improve
waste removal efficiency by following the daily variations in
plant loading.
The objects of this demonstration were to indicate the advantages and
some of the costs associated with computer automation of some phases of
operation for this type of treatment plant. Also, comparison data is
developed to indicate how successfully the new process control schemes
improved removal efficiencies and/or reduced operating expenses. The
implications of the results have broad impact since this project,
although carried out in a new plant (start-up October, 1972), involved
installing a computer and associated automation related instrumentation
in a plant not specifically designed for computerized data logging and
automatic control.
DESCRIPTION OF PALO ALTO REGIONAL TREATMENT FACILITIES
The Palo Alto plant is a regional facility serving the cities of Palo
Alto, Mountain View, Los Altos, and Stanford University. Waste is
primarily domestic at present, although a batch process industrial
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treatment facility is to be_placed in operation shortly. Plant design
capacity is 35 MGD (0.13 Mm /day) and current operation is in the 25 MGD
(0.095 Mm /day) to 30 MGD (0.115 Mm /day) range. The plant is a conven-
tional, secondary treatment plant with final effluent chlorination.
After primary sedimentation, the waste is treated in an activated sludge
process employing clarifiers for activated sludge recycle. Current
loading of BOD is about 30 to 40 thousand pounds per day.
For this study the secondary portion of the plant was modified to oper-
ate in a contact stabilization configuration to provide an inventory of
sludge. Both the contact and the aeration basins were completely mixed.
However, operational difficulties with the contact stabilization con-
figuration at Palo Alto forced revision of the operation to the original
plant design configuration, completely mixed aeration. Consequently, in
the report the secondary portion of the plant is described for two modes
of operation.
Sludge disposal is accomplished by means of incineration and ash dumping
in a nearby solid refuse area. Pre-incineration dewatering is carried
out in sludge thickening tanks and then by centrifuging. A schematic
diagram of the plant process, minus the centrifuges and incinerators, is
given in Figure 1. Figure 2 is a diagram of the plant physical layout.
The secondary portion of the plant can be operated in two modes.
1. Conventional (completely mixed) (Figure 3)
2. Contact Stabilization (Figure 4)
In the conventional mode, all four aerators and associated clarifiers
are employed in parallel as fully mixed reactors. Return activated
sludge is pumped directly from the final clarifiers back to the primary
effluent channel. For contact stabilization, one aerator is converted
to a sludge storage and reaeration basin and the associated clarifier is
taken out of service. The stabilization basin serves the remaining
three aeration basins operated in parallel. Aerators and clarifiers are
linked one to one with no cross-coupling. In the contact mode, return
activated sludge is pumped from the clarifiers to a sludge storage tank,
and from there flows by head differential back to the primary effluent
channel. In both modes of operation, sludge wasting was achieved by
wasting mixed liquor from the aerators directly to the thickeners.
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oo
Qc CENTRATE FROM CENTRIFUGES
SUPERNATANT QTQ
RAW SEWAGE
PRETREATMENT
UNIT
PRIMARY
SED.
TANKS
THICKENERS
WASTE ACTIVATED SLUDGE
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SEDIMENTATION TANKS
AERATION TANKS
FINAL CLARIFIERS
lEGEND'
O . **!.».« »*«)
i ... *vwc »w»
FIGURE 2. SEWAGE FLOW DIAGRAM
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Aeration Tanks
Secondary Clarifiers
Primary
Effluent
o
1
II
III
J
IV
I
II
III
IV
RAS Pit
FIGURE 3.
Air Blowers
PROCESS FLOW SHEET FOR THE ACTIVATED SLUDGE
(CONVENTIONAL MODE)
Secondary
+>
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Tank
Primary
Effluent
ge X
age /
/
y
Deration Tanks
I
t_
II
%_
III
t_
IV
t_
-|
1
1
1
J
1
. 1 .
1
1
1
1
1
1 C
! .
\
, i
Sec
Clarifier out of
f*. service^
T
>\
^_
*
X
S.
k J
:ondary Clarifiers
I
1
II
1
III
1
IV
1
^
^
K
?
fc-
Secondary
Effluent
RAS Pump RAS Pit
Air Blowers
FIGURE 4.
PROCESS FLOW SHEET FOR THE ACTIVATED SLUDGE SYSTEM
(CONTACT STABILIZATION MODE)
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SECTION IV
PHASES OF THE PROJECT
The Palo Alto Computer Project was divided into the following
phases:
Computer Installation
Software Development
Instrument Installation and Checkout
Control Algorithm Design
Control Algorithm Evaluation
The first two phases, computer installation and system software develop-
ment, were done in sequence, and their completion was required in order
to effectively carry out the remaining phases. The remaining phases,
instrument installation and checkout, control algorithm design, and
control algorithm evaluation were carried out concurrently with respect
tb each control system.
Installation of the computer system involved provision for proper power
and grounding, the layout, design, and connection of process signals,
and checkout of all components of the system. The computer was an IBM
System/7, with 16K words of main storage and 2.5 million words of disk
storage. Additionally, a teletype, a card reader, and a magnetic tape
drive were provided. The analog/digital subsystem consisted of 32
analog inputs, 80 digital inputs, and 32 digital outputs.
The system software development was a joint effort between IBM and
Systems Control, Inc. An IBM Systems Engineer was assigned to work
onsite to develop the necessary software. The principal components of
the system software were:
Scan
Limit Check and Alarm
Disk Write
Log
PAX Monitor
The most significant effort was the development of the PAX monitor. The
program was the operating system that allowed foreground/background
processing. Thus, new control systems and data management programs
could be added and tested concurrently with existing scan and control
programs.
12
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The instrument installation and checkout phase involved both existing
instruments (as per original plant construction), and new instrumenta-
tion. The existing instrumentation included for control were:
Magnetic Flow Meters
Air Flow Meters
D.O. Probes
These instruments had to be calibrated and checked periodically as part
of the scan computer program. The additional instrumentation particular
to this project included:
'Suspended Solids Meters
Respirometer
TOG Analyzer
These instruments also had periodic maintenance and calibration require-
ments in addition to initial installation and checkout.
There were five major control systems designed for the full-scale,
activated sludge, treatment plant at Palo Alto. Each control system was
intended to demonstrate the automation of certain functions within the
process. The goal was to show that an automatic control system will aid
the operator in improving the overall quality of the plant effluent
and/or demonstrate some reduction in operating costs. The major control
schemes were:
Aeration Tanks DO Control
Aeration Tanks Control
F/M Control using Air Flow Rate as a Measure of Food Uptake
with DO control (Air/RAS)
F/M Control using Respiration Rate as a Measure of Food Uptake
with DO control (Respirometer/RAS)
F/M Control using Primary Effluent TOC as a Feedforward Measure
of Food Uptake with DO control (TOC/RAS)
Improved removal efficiency was expected because the microbiological
growth environment within the secondary system is more closely regulated
under automatic control. The diurnal variations of flow and organic
loading generally cause fluctuations in F/M values and oxygen transfer
rates, which in turn reduce the overall efficiency of the plant. If, on
the other hand, the oxygen transfer driving force (DO concentration) and
the F/M are maintained at constant values, the growth environment is
optimized, and consequently more soluble organic material will be
oxidized.
13
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Operating costs benefits can be realized since, by following the fluctua-
tions in loading, equipment power usage can be reduced in off-peak
hours. A constant level of operation, by contrast, will necessarily
consume larger amounts of electricity than is actually required for off-
peak BOD loads, and therefore excess capacity is being used unnecessar-
ily for a significant amount of the time.
Evaluation of control algorithms was performed by analyzing extensive
process and laboratory data collected over a 30-day test period for each
controller. Similar data representing manual operation for equivalent
periods was also collected and used for comparison purposes, process
data was automatically monitored and logged every two minutes by the
computer. Laboratory results were composed of composite daily samples
of important plant process streams for 27 days of non-intensive testing
and bi-hourly samples for the last three days of intensive testing.
Intensive test data allowed evaluation of the controller performance in
regulating tasks through the diurnal changes in loading and flow.
Month-long summary data provided the means for comparing average values
of:
Removal Efficiencies
Absolute Levels of Effluent Contaminants
Operating Costs
Controllers were first evaluated for their success in achieving their
design goal (DO regulation, MLSS regulation, F/M regulation). Then,
judgment was made of that control-design goal's impact on effluent
quality improvements and/or operating cost savings as compared to manual
operation. Finally, the benefits, if any, derived from a particular
control algorithm were weighed against all the costs of implementing
that control to determine if it was indeed advantageous for waste water
treatment.
14
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SECTION V
CONTROL ALGORITHM DESIGN
Control algorithms for the various experiments were designed for, and
implemented on, a digital computer with direct input of process instru-
mentation measurements. Algorithms incorporated features designed to
handle such real-time control constraints as measurement availability,
smooth manual-to-automatic transition, and limited control authority, as
well as accomplishing the performance design goals for each control
strategy. For the demonstration project, however, the actual control
action was not performed directly by the computer; rather, a plant
operator was notified of desired control action whenever the process
variable exceeded selected limits. The operator would then make the
necessary corrections as indicated by the computer. This "man in the
loop" procedure was adopted for these reasons:
With the experimental nature of the strategies, it was felt
some judgment should be exercised before a control action was
made.
Since the plant was not specifically designed for automatic
operation, existing blower, pump, and valve-control devices
are not amenable to direct computer operation without consider-
able additional equipment.
The mathematics of the control schemes, dissolved oxygen control (DO),
and mixed liquor suspended solids control (MLSS) are independent of the
two plant operating configurations. Both the DO and the MLSS control
strategies were evaluated in the modified contact stabilization mode.
The remaining schemes, air flow rate as a measure of food uptake (Air/RAS)
and respiration rate as a measure of food uptake (Respirometer/ RAS)
were evaluated in the completely mixed configuration because of operating
difficulties with the modified contact stabilization configuration.
DISSOLVED OXYGEN CONTROL
The system for maintaining sufficient DO in the completely mixed aerators
of the contact configuration is shown schematically in Figure 5*. It is
desirable to keep the DO at a level in the range between 0.5 and 1.5
mg/1 for most efficient operation. Effluent quality deteriorates for
lower DO levels due to problems related to microorganism death or changes
in culture which may lead to bulking sludge. Excessive aeration can
create poor sludge-settling characteristics as a result of floe shearing
or changes in microorganism culture, and effluent quality is again
adversely affected.
*Note: the DO controller can be used, without alteration either for the
contact stabilization or conventional modes of operation.
15
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Dissolved
Oxygen
Measurement
Aeration Tanks
Primary
Effluent|
Secondary Clarifiers
RAS Pit
Air Blowers
Secondary
Blower
Speed
Control
Operator
FIGURE 5. SCHEMATIC DIAGRAM OF OXYGEN CONTROL SYSTEM
(ILLUSTRATED FOR CONTACT STABILIZATION MODE)
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Within the above mentioned range, variation in the DO level does not
have a significant bearing on effluent quality. However, increased
costs are incurred in supplying additional air to hold a higher DO level
than the minimum level for satisfactory treatment. Since oxygen consump-
tion is dependent on the condition of the biological mass and on the BOD
loading which varies throughout the day, the air supply rate must be
varied to achieve the constant DO level necessary for best cost efficien-
cy consistent with good treatment. The DO controller changes the
airflow rate automatically in response to changing oxygen demands and
thereby maintains the desired optimum DO level.
Figure 5 indicates that the DO control algorithm was set to control
the air flowrate to only a single aeration tank based on the measurement
of DO in the tank. The distribution of air to the other three tanks,
and therefore the maintenance of an acceptable DO level, was performed
by periodic manual adjustment of the butterfly valves such that all DO
levels on the tanks used for aeration were equal. Separate control
loops for each aeration tank were not feasible at Palo Alto since there
was no convenient way of independently adjusting the four airflows.
In essense, the DO control algorithm was a conventional proportional-
plus- integral (PI) process control mechanism operating on the DO measure-
ment from one aeration tank. The control mechanism for changing air
flow rate to equal the calculated control demand was carried out by
altering the air blower speeds. Changing the blower speeds in response
to commanded flow changes for one aerator altered the air supply to all
aerators in approximately the same proportion, thus maintaining nearly
equal DO levels in all tanks. As discussed earlier, implementation of
the control commands was through the plant operators who were responsi-
ble for actually setting the computer-calculated flow rates by adjusting
blower rates and/or putting blowers in and out of service.
Control algorithm computations carried out in the computer to determine
the air flow rate necessary to maintain the desired DO level begin with
the raw DO signal- inputs to the computer. This signal was sampled at 6
second intervals by the A/D system. A digital first order equation
having the form
D0£ = D0f + (l-a)DOraw (1)
n n-1 n
processes this 6 second data, further reducing the high-frequency noise
content to yield a smoothed measurement, D0f. The value a = .97 was
used; this value is equivalent to a filter lime constant (T) of 3.5
minutes. The relationship between the averaging factor (a) and the time
constant (T) can be found from the following derivation.
D°f K
D°f ' -T + f D°raw
17
-------
where T is the filter time constant and K is the gain. With a sampling
interval of A minutes, the solution for DO-(t + A) in terms of D0f(t),
where t is real time and s is a dummy integration variable,
D°
f (t+A)
D°
DO (t)
raw
(3)
for the assumption that DO (t) is constant over (t, t+At). With a 6
second scan time (A = l/(l6fwminute)), the equation for a at a time
constant of T minutes, is
a = e .
The algorithm used on the DO signal is the 'velocity* form of the PI
algorithm requiring the controlled variable error value and first derivative,
This form eliminates the problems of "wind-up" that can result with
control authority limitations and integral control action. A polynomial
filter is used to obtain the required derivative of the filtered DO
signal. This filter uses the past four filtered DO values and fits a
second order polynomial to the values to minimize the mean square
residuals. In equation form, this is
A
DO
t-s
2
£
ais
0 < s < 3A
(4)
A
and a_ is a polynomial constant. DO is the output of the polynomial
filter, D0f is the output of the first order filter, and the a. values
are chosen to minimize
Q
min
...a
||DO(t-iA) - DO(T-iA)||
i=0
(5)
The outputs of the polynomial filter are estimates of the DO level, its
first and second derivatives. These are calculated from the quadratic
approximation, as follows:
A
DO
A
D0t
A
66
O
= a,
(a)
(b) (6)
(c)
18
-------
The estimate for DO is then subtracted from the setpoint, SPT, to provide
an error signal, e
efc - SPT - DO (7)
The estimates are input into the 'velocity' PI controller which is
designed to compute the required change in the air flowrate, AQ.
AQA = K(KX e + K2e) (8)
= KC-KjDO + K2e)
where e = the first derivative of the error signal
K.. = is the proportional band gain
K_ = is the integral gain
The choice of tuning constants is made by evaluating the open-loop
response of the DO to a step change in air flowrate, Q.. The details
are as follows. Assume the DO dynamics can be modelled as first order;
then
A regular PI control algorithm will have the form
C'tt^e + K2 /e
QA = K'(K.,e + K0 /e) (10)
Differentiating the DO and control equations, and substituting for
Q , it is found that
A.
DO
2
DO + fVirtK-DO + K-(SPT-DO)) (11)
L *
Collecting terms
dt
K*K'K K K* K*K-
DO + I Y + T JDO + -^- DO -- f- SPT (12)
The dynamics of the closed loop DO-air flow rate system can then be
specified. Usually a critically damped response is desired. There is
considerable redundancy in the controller coefficients, and some can be
assigned values a_ priori.
19
-------
The velocity controller is derived from the PI controller as
Au ,v ' . v -.
u = -^ = K (Kie + K2e)
(13)
Au = (BTAt)(-K DO + K e)
where K = overall gain, and u is velocity, and At is the controller
operating interval of approximately every 1 to 2 minutes for the DO
system.
The final values for the controller gains were derived from on-line
tuning after they had been originally set by assuming a 5 minute process-
time constant. Setpoints used for the controller were 1.0 and 0.75 mg/1
DO, with the first value used in the dry season experiments and the
second for the wet season.
In actual operation of the controller, with commanded changes in air
flowrate calculated every one or two minutes, excessive supervision and
action would be required of the operator if every small command change
was performed. Therefore, a dead band on control commands is incorpor-
ated in the controller to reduce the work load of small random control
changes induced merely by residual measurement noise in the control
signals.
The deadband is implemented by
0 |Au| < Au, ,, ,
1 ' deadband
Au = I (14)
c
Au |Au| > Au
deadband
Figure 6 is a block diagram of the complete DO control algorithm loop.
The items within the dotted line are calculations performed by the
computer. Various additional checks and procedures are incorporated in
the real time control over and above the specific algorithm calculations
to insure proper handling of various operating-environmental changes:
1. Controller will disable if valid measurements of DO and the
current total air flow rate are not available.
2. Controller must be enabled manually once it has been disabled.
3. In the enabling process, the current DO measurement is used
for the initial setpoint to assure a smooth transition from
manual to automatic control. The set-point can subsequently
be changed manually to the desired value.
20
-------
RAW DO
MEASUREMENT
00 TEST AIR/RAS, RESPIROMETER/RAS TESTS
1.0 *g/l 0.75 "g/l
SETP.OINT
COMTUTER FUNCTIONS FOR IK1 ALGORITHM - CYCLE TIME 1 or 2 MINUTES
LOA31KG
FIGURE 6. DISSOLVED OXYGEN CONTROLLER BLOCK DIAGRAM
-------
A detailed flow chart of the complete controller algorithm and operating
logic is given in Appendix A.
When the controller is functioning, the operator is alerted by an alarm
light and is notified of a command change of specified size by the
computer teletype. The light goes off on the next control cycle if no
further command change is required.
MLSS CONTROL
The secondary treatment aerator's MLSS controller was originally intended
as a component in the various forms of F/M control based on food uptake.
A setpoint for MLSS was selected, and the MLSS controller using a MLSS
meter as the primary sensor then adjusted the return activated sludge to
maintain the desired MLSS level. The contact stabilization configura-
tion for plant operation was employed during this phase.
Contract stabilization treatment was, however, abandoned after the MLSS
test period as a result of unsatisfactory plant operation.* The decision
to return to conventional, completely mixed aeration with direct sludge
recycle from secondary clarifiers was made by plant personnel with
agreement of the EPA Cincinnati laboratory staff. Therefore, the MLSS
controller (although designed, tested, and evaluated) was not utilized
for its ultimate purpose. Results are still presented here, however,
since they may prove useful if the plant operational problems are over-
come or are not present at another facility.
The form of the MLSS control algorithm is completely analogous to the DO
algorithm. The basis is, again, a .standard proportional-plus-integral
process controller. In this case, the measurement is MLSS. Solids
concentrations are measured only in aerator 1, but this measurement is
representative of all the aerators since they are fed from a common
influent channel. The control mechanism is the RAS pumping rate which
is controlled by operator adjustment of RAS pump speeds. First order,
low-pass and polynomial filters are again used to condition the measure-
ment. The velocity form of PI control is used, as well as the dead band
oh the calculated control-command output.
Tuning the MLSS controller follows the same procedure as for the DO
control loop, except that the process time constant is on the order of
four or five hours. Controller cycle time is set at 15 minutes. Operator
notification of when an RAS flow rate change is needed is again accom-
plished by means of a light signal.
*
Excessive floating material thought to be dead microorganisms was observed
in the secondary clarifiers. The sludge storage basin was thought to be
'the source of the problem since the problem largely disappeared as soon as
the conventional mode of operation was reinstituted.
22
-------
Figure 7 is a process schematic for MLSS control. Figure 8 is a block
diagram of the MLSS algorithm computations. Real time checks and proce-
dures similar to those used in the DO controller are also performed in
the MLSS controller.
1. Valid measurement checks
2. Manual controller enabling
3. Smooth transition from manual to automatic operation.
A detailed flow chart of the complete controller algorithm and operating
logic is given in Appendix A.
AIR/RAS CONTROL
The objective of this study was to demonstrate a controlled F/M and to
determine the effects of a controlled F/M on secondary treatment removal
efficiency. Conventional manual operation maintains essentially a
constant MLSS, and operates at an average F/M, based on daily average
food and microorganism levels. In fact, however, plant loading varies
quite significantly throughout the course of a day; thus, there are
periods when the F/M value exceeds its average value. The three F/M
oriented algorithms are:
Air/RAS
Respirometer/RAS
TOC/RAS
In all three,'RAS flow is used to adjust MLSS in order to keep F/M
constant as the food utilization or aerator loading varies. The primary
difference among the three controllers is in the means used to measure
the food.
For the Air/RAS Controller, the air supplied to the completely mixed
secondary treatment process is used as an indirect measure of biological
respiration and therefore of the substrate (food) utilization, dF/dt.
(See Appendix section B.2 for detailed development of the relation
between air flow and substrate utilization).
f ' C A + C2
where c.. = regression coefficient calculated using plant operating data
Cx = regression coefficient calculated using plant operating data
Q. = air flow
A.
23
-------
MLSS Measurement
Aeration Tanks
Secondary Clarifiers
to
AirTlowers I
Operator j j
Pump Speed Control
Secondary
Figure 7. SCHEMATIC DIAGRAM OF THE MLSS CONTROL SYSTEM
(ILLUSTRATED FOR CONTACT STABILIZATION MODE)
-------
r
t_n
i
IRAW MLS
MEASUREME
I
SETPOINT
1500 »g/l
. 1
^ fc NOISE SUPPRESSION £SIS£ W f^"
FILTER TIKE " »« £ , \^
COMPUTER FUNCTIONS FOR MLSS ACLORITHM - CYCLE TIKE 15 MINUTES
o*c f*nu
smfrtrnm sni Tns SECONDARY PROCESS "" '"""
METER AERATORS ~" '
t
1 B4C PIOU
TOD LOADING METEi(
»A<; _ , . _
. PI FLOW
,, CHANCE DEADBAXD +/^>V
i. *i *» * y-
1
LIMITS
8 M..D
20 Mia
I.IUIIT SICNAL 4
ffiSSACE IF
FLOW (.HANI1E
REQlilKED
S*^ '
Xi^ATOR ACT^V-f- -*
OmlATOR A ^>
^
-j
FIGURE 8. MLSS CONTROLLER BLOCK DIAGRAM
-------
With the desired F/M, the MLSS level necessary to achieve that ratio can
be calculated. The RAS flow is then adjusted to bring the actual MLSS
to the desired value.
Originally, it was intended that the MLSS controller would be used in
cascade to bring about the desired changes in MLSS. The setpoint to the
MLSS controller would be the required solids level for a constant F/M
ratio, as calculated by the Air/RAS controller. As previously discussed
however, the MLSS controller is incompatible with the plant in the
completely mixed mode of operation during the F/M ratio controller
tests. The incompatibility is caused by the fact that the wasting rate
and MLSS concentration are not independent. Appendix section B.4 con-
tains the derivation of the relation between F/M, U, and the mean cell
residence time, 0 , which could be used to set the sludge waste rate:
U
K
'd
(16)
where K, is the endogenous respiration rate constant, Y is the yield
coefficient and f is the ratio of the volatile to the total suspended
solids. However, the dynamic biological model constants K , Y, and f
are subject to considerable variability and 0 is not known precisely Y
so that U is subject to variability.
Therefore, the MLSS controller was not used in cascade with the various
forms of F/M control. Instead, the RAS flow was set based on what the
MLSS solids level should be in a steady state operation. This procedure
ignored the concentration lag inherent in the aerator tanks' retention
time, so there was some delay between changes in the actual MLSS and the
commanded value. The advantage of the steady state operation approach
is, however, a self-regulating characteristic with regard to the average
F/M and the final clarifier sludge level.
The algorithm for determining the RAS flow, QD , is
K
C
\ ~
c
and a detailed derivation of the algorithm, based on mass steady state
balances around the aerators, is given in Appendix B.I. X^ is the
average RAS suspended solids concentration obtained from plant labora-
tory-monitoring analyses and is assumed constant. The desired MLSS
setpoint, X , is derived from Equations 15 and 16.
26
-------
dF/dt [C1QA
c UV U V
a a
The self regulatory or smoothing feature of this algorithm, with respect
to average MLSS level and clarifier sludge level, occurs because of the
assumed constant, X^. In actuality, average JL, varies in proportion to
the average sludge^ level in the clarifiers. This means that the average
solids returned, QR X^, will go up when the clarifier sludge level goes
up since Q_ (average value) remains relatively constant; this phenomenon
automatically regulates the clarifier sludge level. A similar smoothing
effect is also produced in the aerators where a constant volume of mixed
liquor wasted to the thickener automatically regulates variations in the
average MLSS concentration.
Implementation of the Air /RAS. control algorithm embodied in Equations 17
and 18 requires measurement of total air flow, Q., plant flow, Q, and
RAS flow, QR. Fortuitously, the measurement of plant flow is at the
plant headworks and a thirty minute lag in flow was observed across its
primary plant; a feedforward lead of about 30 minutes is incorporated in
the algorithm, compensating to some extent for the previously discussed
lag inherent in the algorithm.
Figure 9 is a schematic of the F/M control plan. An algorithm block
diagram of the Air/RAS form of F/M control is given in Figure 10.
Additional, real time, operation-oriented features of the controller
include:
Deadband on commanded RAS changes
Measurement validity checks
RAS command limits
RAS-pump, suction-pit level control
The controller commands are carried out as described for the MLSS con-
troller with signal-light notification to the operator to change RAS
flows by adjusting RAS pump speeds. Deadband is therefore incorporated
to avoid frequent, low-level, command changes. Measurement validity is
checked every 30 minutes when the controller cycles.
RAS command limits are incorporated primarily for low flow conditions.
Insufficient RAS flow (below between 6 to 8 MGD(.023 to .030 Mm /day))
causes plugging of the clarifier decanting lines. A procedure necessary
to enable even that low-flow limit involves manually choking down the
butterfly valves of its clarifier draw-off lines below 10 (.038 Mm /day)
MGD RAS flow. This procedure keeps the RAS-pit level low enough to
maintain sufficient head on the decanting lines to prevent plugging.
27
-------
Aeration Tanks
Secondary Clarifiers
Primary
Effluent
N)
00
"Food" Measurement
or Estimate I
II
L-J
III
IV
t I
Computer
L_
n
i
ii
in
IV
Operator
Air Blowers
I
Pump Speed Control
Figure 9. SCHEMATIC DIAGRAM OF FOOD TO MICROORGANISM RATIO CONTROL SYSTEMS
(ILLUSTRATED FOR CONVENTIONAL MODE)
Effluent
-------
NJ
F/M RATIO SETPOINT
F/M RATIO CONTROL
CALCULATION OF RAS
FLOW COMMAND
COMPUTER FUNCTIONS FOR AIR/RAS ALGORITHM
CYCLE TIMF. 30 MINUTES
VOLUMETRIC BOD LOADING
PLANT FLOW
FIGURE 10. AIR/RAS CONTROLLER BLOCK DIAGRAM
-------
The algorithm monitors RAS flow commands and types a message for the
operator when a change in valve positions is required.
RESPIROMETER/RAS CONTROL
This algorithm is completely analogous to the Air/RAS controller in that
the intent is to maintain a constant F/M value in the secondary aerators.
The major difference is in the instrumentation employed to determine the
food uptake rate.
Both controllers estimate food uptake from microorganism respiration.
Whereas the Air/RAS form uses the air supplied to the aerators as a
measure of respiration, the Respirometer/RAS incorporated the Badger
Meter Company's "Biological Respirometer" for direct indication of
respiration from a sample of mixed liquor. The following relationship
between measured respiration rate per unit volume, R, and food uptake is
developed for the Badger Respirometer in Appendix section B.5:
(19)
dt al.O-YyL
where V is the volume of the aerators. In the Palo Alto plant, values
for the parameters in Equation 2.9 are estimated as
Kd = 0.05 days'1, X ^1200 mg/1,
Y - 0.5, y 1.42, L - 0.5
so that in the algorithm calculation
dF 1
dt .745
R - 2.5
mg/1 hr (20)
Typical readings for R average around 24 mg/1 hr.
The Respirometer/RAS algorithm calculations therefore employ the expres-
sion for dF/(dt) of Equation 20 in Equations 17 and 18 to determine the
RAS flow commands. A block diagram of the controller is given in Figure
11 and is seen to be exactly the same as the Air/RAS, except for the
replacement of the air flow measurement by the respirometer measurement.
Additional real time checks and procedures common to all the F/M control-
ler are also included:
Deadband on commanded RAS changes
Valid measurement checks
30
-------
r
F/M RATIO SETPOINT
0.33 DA ITS
-1
F/M RATIO CONTROL
CALCULATION OF
RAS FLOW COMMAND
I COMPUTER FUNCTIONS FOR RESPIROMETER/RAS ALGORITHM
I CYCLE TIME 30 MINUTES
OXYGEN UPTAKE
RATE
VOLUMETRIC
PUNT FLOW
FIGURE 11. RESPIROMETER/RAS CONTROLLER BLOCK DIAGRAM
-------
RAS command limits
RAS-pump suction-pit level control
Operator procedures for implementation of command changes is the same as
for the Air/RAS controller.
TOC/RAS CONTROLLER
Appendix B.3 details the relationship between secondary treatment load-
ing (food-inflow rate) and biological food utilization. The development
shows that there is a lag equivalent to a first order time constant of
approximately 10 minutes between food influx and subsequent utilization.
For the Respirometer/RAS controller, there is an additional measurement
lag of 1 hour in the Respirometer operation. With the Air/RAS, there is
a delay of 10 to 20 minutes in the response of the air flow measure of
respiration due to lags inherent in the DO controller which adjusts the
actual air supply rate. Altogether then, there is a lag in the first
two forms of F/M control of anywhere from 20 to 70 minutes between
aerator loading changes and actual measurement of the new loading for
control purposes.
The intent of the TOC/RAS controller is to avoid these long, food load-
ing, measurement lags and thus improve the response capability of F/M
control. This was to be accomplished by an on-line measurement of TOG
in the secondary influent. A relationship between instrument TOC mea-
surements and laboratory BOD,, measurement in the influent, was to be
determined, and then a measurement of the incoming load could be calcu-
lated as QS .
With the QS measurement substituted for dF/(dt) in Equation 19, a
feedforward°MLSS command for F/M control is produced. The expectation
was that this feedforward TOC/RAS control would yield a better regula-
tion of F/M by compensating more fully for the measurement lags dis-
cussed above and partially for the aerator retention-time lag mentioned
previously.
Other features of the TOC/RAS control algorithm are the same as described
for the Air/RAS and Respirometer/RAS controllers. Commanded changes in
RAS pumping rates were also to be performed in the same manner as for
the other F/M controllers. A block diagram of the TOC/RAS control-
algorithm design is given in Figure 12.
32
-------
CO
OJ
r
SETPOINT
0.33 DAYS"1
F/M RATIO CONTROL
CALCULATION OF RAS
FLOW COMMAND
COMPUTER FUNCTIONS FOR TOC/RAS ALGORITHM
CYCLE TIME 30 MINUTES
LIGHT SIGNAL &
MESSAGE IF
FLOW CHANGE
REQUIRED
SECONDARY PROCESS
AERATORS
VOLUMETRIC
PLANT FLOW
FIGURE 12 TOC/RAS FEEDFORWARD CONTROLLER BLOCK DIAGRAM
-------
SECTION VI
EXPERIMENTAL DESIGN
SCOPE
This section disucsses the experimental plan for accurate comparisons of
performance and cost effectiveness of the manually and computer con-
trolled operation of the Palo Alto Wastewater Treatment Facility. The
plan defines the data gathering and analysis requirements, as well as
the plant operation requirements for each of the phases of the program.
Included are details on where each sample was collected, how it was
collected, the type of analysis that was performed on the samples in the
laboratory as well as the format of data that was inserted into the
digital computer.
In formulating the experimental design plan, care was exercised to
provide several features which would ensure the validity and utility of
the results. These features include:
Accurate benchmark of the manually operated process by estab-
lishing an operating procedure consistent with average operat
ing procedures of manually controlled wastewater treatment
plants within the State of California.
Provision for long-term relative evaluation of each of the
control systems in terms of ability to enhance the quality of
discharges as well as reduce operating costs.
Provision for short-term detailed evaluation and analysis of
the plant under both manual and automatic control over the
complete dynamic range of operation. This will lead to a more
complete understanding of the process itself, as well as a
quantitative evaluation of performance parameters associated
with the control modes.
Allowance for potential stress on each control system to allow
a complete evaluation under normal and abnormal operating
conditions.
Specifically, this section describes the general method of testing and
an associated time-phased schedule; the manually controlled portion of
the test in terms of both the operating procedures to be employed and
the data gathering techniques; the automatic control portion of the
experiments, again in terms of the operating procedures and data collec-
tion methods; and, finally the types of data analysis performed on the
collected data base.
34
-------
EVALUATION PLAN
In order to obtain a performance and cost effective evaluation of the
comparison of the plant operating under manual and automatic control, a
methodology was established which provided an adequate amount of accur-
ate data concerning the process. The general experimental plan that was
used to meet these objectives is outlined in the steps below:
Step 1 - For an initial period of approximately four weeks, the contact
stabilization process was controlled manually according to procedures
which represent average control of water treatment plants within the
State of California (e.g., air-blowing rate was adjusted twice daily).
This served as a process benchmark for future automatic control modes.
During this period of manual control, data collection and analysis was
divided into two phases; a non-intensive phase and an intensive phase.
The non-intensive phase of data collection and analysis lasted for
approximately three and one-half weeks and was oriented toward obtaining
average plant-performance characteristics over an extended time period.
Data collected, for example, provided the average, daily, BOD,, reduction
over the period. In addition during this phase, some data, such as
suspended solids levels and DO profiles in the aerators, was collected
at relatively high frequencies-nominally every two hours. This verified
that the plant was operating as designed and that instruments were
operating properly and were properly calibrated. The intensive period
of data collection spanned a three-day period which represented both the
extreme operating conditions of the plant, as well as an average operat-
ing condition. The days selected for intensive data collection were
Sunday (which represents an abnormally low, flow profile during the day,
as well as a different flow pattern from the remaining six week days),
Monday (which represents the peak flow condition and most stressing
situation for the plant) and Tuesday (which represents an average,
daily, flow condition and profile). During this period, all relevant
plant-performance data was collected and analyzed on a two-hour basis to
provide detailed information concerning the dynamics of the plant (e.g.,
daily BOD , TOG and COD profiles at two-hour intervals at points within
the plant;. This information was then utilized for both the subsequent
detailed comparative analysis of the control modes, in addition to
providing detailed information concerning the characteristics of the
plant. Details concerning the exact location and frequency of data
collection and analysis is provided later.
Step 2 - At the completion of the intensive data-collection phase of
manual operation, the first automatic control system (DO control) was
activated using the contact stabilization configuration. The DO control
system was operated for approximately four weeks to provide (a) suf-
ficient time for transients associated with the change in control strategy
to decay and for the plant to assume steady state operation and (b) a
large enough data base to perform meaningful comparative evaluation of
average plant performance. Data collection and analysis consisted of a
35
-------
non-intensive phase of approximately three and one-half weeks followed
by an Intensive phase on the concluding Sunday, Monday and Tuesday.
Data collection and analysis was identical to the manual control period
with the exception that, in addition to plant performance data, only
sufficient samples of parameters, (such as DO level in each of the
tanks) required to calibrate sensors were taken during the non-intensive
phase.
Step 3 - The next control scheme (MLSS) was evaluated by operating its
plant as in Step 2 above with the contact stabilization configuration.
Step 4 - The Air/RAS control scheme was evaluated by operating the plant
under the complete mix configuration.
Step 5 - After installation of the TQC analyzer and the respirometer,
the Respirometer/RAS control system was evaluated in a manner identical
to the procedure given in Step 4 above. Because of difficulties with
the TOC analyzer this control strategy was not implemented.
It was felt that the above methodology represented a cost and time
effective experimental procedure for the comparative evaluation of the
control strategies. It provided for collection and comparison of ade-
quate amounts of data to monitor and compare the process over ranges of
operation in a cost effective manner.
MANUAL CONTROL PROCEDURES
The automatic control procedures and algorithms have been described
previously. But in order to accurately compare performance and cost of
the automatic control systems, it was important that the manual operation"
of the plant be standardized during the evaluation phase. As described
below, the major operating procedures employed at the plant during
manual control had been derived from analyses of typical operations of
wastewater treatment facilities of comparable size and operation in the
State of California. It should be carefully noted, however, that the
control policy described below represents a typical method of activated
sludge process control; i.e., the procedure is deemed average and is not
to be taken as representative of what could be done at Palo Alto. The
intent was to determine the average efficiency of Palo Alto's secondary
system when operated under a conventional manual control strategy.
The major control operations influencing the secondary process are the
air flowrate into the aeration tank, the return activated sludge flow-
rate into the sludge storage tank and the mixed liquor wasting rate.
The control strategy for each of these elements is described below.
The air flowrate to the aerators was adjusted twice daily during manual
operation. At 0900 hours each day, the No. 1 and No. 3 blowers were set
at full speed, and No. 5 blower set at its minimum speed (for peak flow
conditions). There were no changes in the individual tank valve settings.
36
-------
At 2200 hours each day No. 3 blower was set to its minimum speed and No.
5 blower was shut down. The No. 1 blower remained at full speed for the
entire test period.
Summary Blower
Control
High Speed
Low Speed
Time
0900 hours
2200 hours
#1
Full
Full
#3
Full
Min.
#5
Min.
Off
It is noted that during all phases of both manual and automatic control
operation, the butterfly valves between the blower and the aerators
remained fixed.
The RAS flowrate was adjusted once per day during manual operation.
This rate was computed each day at 1300 hours based on the 30-minute
settled volume. The return rate for the next 24 hours was determined by
the formula:
_ Q (set, vol.)
WR 1000 - (set. vol.)
where Q = return activated sludge flowrate (MGD),
K
Q = plant flowrate (MGD)
set. vol. = 30-minute settled volume (ml)
For the following (representative) conditions,
30 Minute Settling Test = 250 ml
Expected Plant Flowrate = 25 MGD = Q
the calculation would be
QR = (25) (250)7(1000-250) = 8.33 MGD (.032 Mm3/day)
The return activated sludge pump speed was-then set to return activated
sludge at a flowrate of 8.33 MGD (0.032 Mm / day). No adjustments in
the return rate were made until the next day at 1300 hours.
The above procedure was adopted based on the consideration that the peak
flows occur at approximately 1300 hours and that acceptably representa-
tive averages (i.e., 30 minute settling) could be obtained at that time.
This method has been used successfully at the plant to this date.
As in completely mixed operation, the wasting rate during operation in
the modified contact stabilization configuration was adjusted once daily
37
-------
during the manual operation. This rate was that required to maintain a
mean cell residence time of 10 days and was adjusted each day at 1300
hours. The wasting pump speeds were adjusted to maintain a constant
waste mixed liquor flowrate for the next 24 hours. Wasting was accom-
plished by wasting mixed liquor directly from areator #1. The waste
mixed liquor flowrate was computed as follows:
(5. 61) (MLSS ) + (1.87) (MLSS #2) - (6 ) (Q) (SE )
Q-fJll \ = _ AVC, _ C _ 88
WMLU'1; (MLSS #1 - SE 9 )
ss c
where SE = secondary effluent suspended solids (mg/1)
SS
MLSS#x = suspended solids in aerator #x (mg/1)
MTOC MLSS II + MLSS #3 + MLSS #4 , ,,.
MLSSAVE -- 3 - (mg/1)
6 = mean cell retention time (days)
Q = average plant flowrate (MGD)
O.UMT = waste mixed liquor flowrate (MGD)
For the representative parameters given below, the calculation becomes:
MLSS II = 2618 mg/1
MLSS #3 = 1926 mg/1
MLSS #4 = 1875 mg/1
2618 + 1926 + 1875 mg/1
Q = 25.0 MGD (.095 Mm3/day)
MLSS #2 = 6136 mg/1 (sludge storage)
*, _ (5. 61) (2139. 6) + (1.87) (6136) - (10) (25) (30)
QWML ffl " (2618 - 30) (10)
= 0.617 MGD (.0023 Mm3/day)
Note that this flowrate is the actual waste-mixed-liquor flowrate from
the II aerator. To set the actual waste rate, all secondary effluent
pumps were shut down, and the WML pump speed was adjusted to obtain the
desired flowrate
Daily Sample Collection and Analysis Period (Non- intensive)
During the non- intensive phase of the initial manual- control period, a
substantial number of samples were collected and analyzed. This was
done to assure that the plant was functioning properly and that all
instruments were calibrated and operating correctly. In addition, the
38
-------
sampling was compatible with a dry run of the intensive sample-
collection and analysis phase at the conclusion of the manual control
period. Similar sampling was performed during the control studies but
not necessarily at the same sample frequency.
The location and method of sample collection is extremely critical to
obtain representative laboratory results. Therefore, it was essential
that an adequate and uniform procedure be used in collecting samples.
All samples were taken by the following procedures, using quart bottles
to obtain adequate samples.
Raw Sewage - The sample was taken from the primary influent channel.
The first hatch cover (before the thickeners) was removed, and the
sample was collected at a depth of 2 - 4 feet (0.6 - 1.2 m).
Primary Effluent - In order to obtain a representative sample of primary
effluent, a composite was formed. The composite grab sample was gen-
erated by mixing equal volumes from the effluent launders of those
primary clarifiers in service.
Secondary Effluent - A grab sample of secondary effluent was obtained
from the line connected to the 60 inch (1.5 m) secondary effluent line.
This line is downstream of the clarifiers and is itself a composited
sample of secondary effluent.
Final Effluent (after chlorination) - A grab sample from the effluent
junction box was taken. This sample was taken at a depth of 2 feet (1.2
m) to ensure mixing.
Mixed Liquor - A separate sample from each of the three aerators was
taken. The samples were collected at the following locations (see
Figure 13) platforms flB, #3C, #4A at a depth of 2 - 4 feet (0.6 - 1.2
m). These sample locations were selected since they are the farthest
locations from the mixed liquor in flows. The samples were taken for
the purpose of DO probe and MLSS meter calibration. During conventional
operation, an addition sample was taken from aerator 2, at platform 2A.
Return Activated Sludge - A grab sample from #2A aeration platform
(sludge aeration tank) was taken at a depth of 2 - 4 feet (0.6 - 1.2 m).
During conventional operation the sample was taken from the RAS pit.
For the initial non-intensive manual operation phase, all samples indi-
cated above were collected daily on the even hours (i.e. 00,.02,...,
2200 hours) and composited on a 24 hour basis. During the period of
automatic operation the primary effluent, secondary effluent, final
effluent, mixed liquor and return activated sludge were sampled three
times a day nominally in the midpoint of each shift.
39
-------
RAW
SEWAGE
SAMPLE POINTS
1. RAW SEWAGE
2. PRIMARY EFFLUENT
3. RETURN ACTIVATED SLUDGE
4. SECONDARY EFFLUENT
5. FINAL EFFLUENT
PRIMARY
CLARI-
FIERS
:HLOR-
INATOR
FINAL
EFFLUENT
RETURN ACTIVATED
SLUDGE PUMP
SCHEMATIC DIAGRAM OF THE PLANT
WITH PROCESS SAMPLE POINTS INDICATED
FIGURE 13
-------
During this period, the raw sewage, primary effluent, secondary effluent,
and final effluent were analyzed every 2 hours for pH. These samples
were then composited throughout the day and analyzed the following day.
The composited sample was also analyzed for suspended solids, BOD,., TOC,
COD, NH., NO , N03> and ortho phosphates.
5'
In all cases the collected samples were analyzed according to accepted
methods. Where possible, methods indicated in Reference (3), "Standard
Methods for the Examination of Water and Waste Water," were utilized.
Specifically, the sample analyses for the quantities of interest were as
indicated in Table 1.
Table 1. ANALYTICAL TECHNIQUES
Quantity Desired
Suspended Solids
BOD-
COD
TOC
NH3
N03
N02
Ortho Phosphates
PH
30 Minute Settling
Sludge Volume
Index (SVI)
Sample Analysis Technique
Gravimetric Method
Winkler Method - Azide Modification
Potassium Bichromate Oxidation
TOC Analyzer (Envirotech)
Specific Ion Electrode
Photometry
Photometry
Photometry
Electrometric
Standard Method
/30 min. settling vol. in aerator \
suspended solids in aerator
/
x 1000
Bihourly - Data Collection and Analysis Period (Intensive)
The data collection and analysis performed during the intensive sampling
of the initial manual-control period was intended to provide: (1) detail-
ed information regarding the processes within the plant, and (2) a data
base for detailed comparison of the control system effectiveness. The
data gathered during this phase was used to generate the important
statistical-performance parameters for the analysis phase of the study.
Similar intensive sampling was also performed during the control studies.
41
-------
The samples were collected from those locations described previously.
Twelve samples were collected daily, on the even hours. In addition,
during the automatic control operation and for the five-day period prior
to the Sunday, Monday or Tuesday intensive data collection, the mixed
liquor and return sludge were sampled four times during the day shift
for the purpose of calibration of sensors and monitoring their perfor-
mance.
Sample collection analysis was as indicated previously with the excep-
tion that the bi-hourly samples were not composited. That is, each
sample was analyzed for suspended solids, BOD,., TOG, COD, NH_, NO , NO
and ortho phosphates. Hence, a complete set of thirty-six data points
over the three day period were available for analysis.
DATA ANALYSIS
Data base variables consisted of two types: on-line process data and
laboratory data. Process data was recorded automatically by the System/7
on-line every six seconds. At two-minute intervals, data was trans-
ferred to the disc storage. On a once-per-day basis this data was
recorded on magnetic tape for subsequent analysis. A list of the procesa
variables recorded is given in Table 2.
Laboratory data was entered into the on-site System/7 through the use of
the LAB program. This program accepted data via the teletype for any
hour of the day within the preceding 15 days. Normally, all laboratory
data from a given day was not available for 5 days (due to the 5 day
BOD. period), and the 15-day period allowed for weekends and other
potential delays. Again, data was transferred from the System/7 to
magnetic tape for subsequent analysis. Table 3 contains a list of the
laboratory data recorded.
A brief description of the data analysis techniques that were utilized
to perform the comparative analysis of the performance of control scheme^
is given on page 45.
Basically, the data analysis consisted of: (1) performance and cost
comparison over the full 28-day period utilizing, the averaged and
composited daily data, and (2) detailed performance and cost comparison
over the three-day intensive period, utilizing bi-hourly process and lab
data.
Appendix C contains the data for the manual control period in the form
in which it was used for the comparative analysis studies. As illus-
trated in the Appendix, the data base was used to compute the following:
1. Daily data for each of the 28-days of the particular control
phase. This was later utilized to compare the average perfor-
mance of the schemes during the period. As illustrated,
42
-------
Table 2. PROCESS DATA
Description
Units
Total plant flow
Los Altos flow
Mt. View flow
pH for total plant flow
DO #1
DO #2
DO «3
DO #4
Airflow #1
Airflow #2
Airflow #3
Airflow fit
Thickener HI flow
Thickener 01 density
Thickener #2 flow
Thickener #2 density
Thickener f'3 flow
Thickener t'3 density
Thickener rf'4 flow
Thickener #4 density
RAS flow
WAS flow
MLSS
Chlorine flow #1
Chlorine flow 112
Chlorine flow #3
Chlorine residual 111
Chlorine residual 02
Chlorine residual 03
Sulfer dioxide flow
Filtered DO (1)
Filtered DO (2)
Filtered MLSS (1)
Filtered MLSS (2)
mgd
mgd
mgd
pH units
mg/liter
mg/liter
mg/liter
mg/liter
cfm
cfm
cfm
cfm
gpm
Percent of full scale
gpm
Percent of full scale
gpm
Percent of full scale
gp-
Percent of full scale
mgd
mgd
mg/liter
Ib/day
Ib/day
Ib/day
mg/liter
mg/liter
mg/llter
Ib/day
mg/liter
mg/liter
mg/liter
me/liter
43
-------
Table 3. LABORATORY DATA
RAW SEWAGE SS
RAW SEWAGE BOD
RAW SEWAGE TOC
RAW SEWAGE COD
FINAL EFF SS
FINAL EFF BOD
FINAL EFF TOC
FINAL EFF COD
RAW SEWAGE NH3
RAW SEWAGE N02
RAW SEWAGE NO3
RAW SEWAGE ORTHO PHOS
PRIMARY EFF SS
PRIMARY EFF BOD
PRIMARY EFF TOC
PRIMARY EFF COD
PRIMARY EFF NH3
PRIMARY EFF N02
PRIMARY EFF NO3
PRIMARY EFF ORTHO PHO
SECONDARY EFFLUENT SS
SECONDARY EFF BOD
RAW SEWAGE PI1
PRIMARY EFF PH
SECONDARY EFK PH
FINAL EFF PH
MIXED LIQUOR TEMP
MIXED LIQUOR SVI
MIXED LIQUOR SS
MIXED LIQUOR VSS
MIXED LIQUOR DO
MIXED LIQUOR SET VOL
RETURN SLUDGE SS
WASTE SLUDGE SS
SECONDARY EFF TOC
SECONDARY EFF COD
SECONDARY EFF NH3
SECONDARY EFF N02
SECONDARY EFF NO3
SECONDARY EFF ORPHOS
FINAL EFF NH3
FINAL EFF N02
FINAL EFF N03
FINAL EFF ORTHO PHOS
-------
computed variables will consist of:
a. Typical Process Data - mean, minimum, maximum and stan-
dard deviation of the process variables.
b. Daily composite lab data
c. Daily loading of important performance variables
d. Daily efficiency of contaminant removal for each of the
four stages of the plant
3
e. Daily average respiration loading (Ibs. loading/1000 ft.
of aeration tankage)
2. Monthly data for the 28-day period of each phase. This was
later utilized to compare the long-term performance of each
control strategy. Specific variables to be computed included;
a. Process data for the period - mean, minimum, maximum and
standard deviation of each variable. This was later used
to compute, for example, the average DO level attained
for the month.
b. Loading data summary
c. Plant air consumption (allows cost comparison associated
with DO control)
d. Monthly efficiency (for comparison of contaminant reduc-
tion levels)
e. Respiration summary.
45
-------
SECTION VII
HARDWARE AND SOFTWARE IMPLEMENTATION
The implementation of the instrumentation and computer systems were
paramount to the successful completion of this project. This included
hardware installation, calibration and checkout, and software integra-
tion. . This section discusses these aspects of the instrumentation and
computer system. Table 4 summarizes costs and maintenance data on the
instrumentation, while Table 5 and 6 summarize similar information on
the computer system.
INSTRUMENTATION
The DO system at Palo Alto consists of four Weston & Stack "Model A40"
probes and four "Model 3000-1A" DO analyzers. These probes were origi-
nally installed as part of the original plant construction.
All the DO probes were cleaned, checked and calibrated initially (DO-
Probe membranes must be periodically cleaned since they tend to clog,
resulting in lower readings and poor sensitivity). Cleaning operations
were performed once every two weeks, usually taking about one hour to
clean and check all probes. Approximately once every three months, all
probes were checked, cleaned, and recalibrated. This normally required
about four hours for all probes.
The output of the DO analyzers is a 4-20ma. signal. This ^signal proved
to be very noisy (electrically), probably resulting from the small
oscillatory variations of the rotor of the DO probe. A first order
filter was employed in the computer to "smooth" out the signal. Addi-
tional filtering was provided by a polynomial filter in the DO controller.
The DO controller, as implemented, used only one DO probe. The original
cost of a single DO system as above was about $1500. Since these were
originally installed as part of plant construction, there was no addi-
tional cost to this project. (See Table 4).
Suspended Solids Meter
The MLSS suspended solids meter originally purchased for this project
was the Keene "Model 8200 SCCS". Installation of the probe was straight-
forward using simple pipe mounts. Shortly after installation, the
instrument failed. The problem was traced to a leak in the probe seal.
The probe was then disassembled, dried out and then reassembled.
The probe was reinstalled but failed to lend itself to a stable calibra-
tion. A Keene factory engineer checked the Keene meter. The probe
assembly was replaced, the instrument was recalibrated, and it since has
been working quite well (Figure 14).
46
-------
Table 4. INSTRUMENT COSTS
Monthly
Instrument
DO Probe
MLSS Meter
Keene
Biospherics
Respirometer
TOC Analyzer
Cost
$
1,500
3,500
2,400
5,200
10,450
Installation3
$
600
240
120
600
600
MH
40
16
8
40
40
Utilities'3
$
nil
nil
nil
33C
16
Supplies
$
5
0
0
5
5
Maintenance
$
45
15
15
15
480
MH
3
1
1
1
32
Assuming $15/man-hour ($15/MH)
Assuming water at 20c per 1,000 gallons and electricity at Ic per KWH
Respirometer uses up to 200 gallons of water per hour.
A Biospherics "Model 52L" suspended solids meter was next installed, and
the data correlated quite well with the laboratory results (Figure 14).
It was used for the MLSS test. It did fail once, necessitating a
replacement capacitor in the control unit.
Both instruments track diurnal variations quite well. During the Air/RAS
testing, the Keene instrument was biased higher than the Biospherics.
After a bias adjustment, the Biospherics read higher, but this has since
been more carefully "zeroed out".
Both instruments have been otherwise maintenance-free. The Keene has
the advantage of a direct digital readout in PPM, and no moving parts.
The Biospherics unit is self-cleaning (not a problem here); hence, it
has some moving parts. Eventually this will require replacement of an
"0" ring. While the Biospherics unit has a meter readout, it has two
scales (0-3000 PPM and 0-10,000 PPM), and the Keene unit covered a range
of 500-5000 PPM digitally. The Biospherics thus can also be used to
measure return activated sludge concentrations if desired.
The original Keene suspended solids meter was purchased for $3,500. The
total installation time was about two man-days (including running of
cable). The Biospherics unit has a purchase price of $2,400. Its
installation took about one man-day (see Table 4). Both meters were
installed in aerator number one, adjacent to each other.
47
-------
CD
Biospherics
Keene
Laboratory
RESPIROMETER TEST 3/10 - 3/12
DO/RAS\rEST*2/10 - 2/12
800
4 8 12 16 20 0
8 12 16 20 0 4
Hour
8 12 16 20
FIGURE 14. SUSPENDED SOLIDS METER COMPARISONS
-------
Respirometer
The respirometer that was used was a Badger "Model OD 2000". Initial
installation of the instrument took about five man-days, due to some
necessary plumbing work (shown schematically in Figure 15). The instru-
ment needed sample, water, and drain connections.
Initially, the instrument was plagued with an electronic problem that
resulted in erratic output signals. Once this was corrected, the instru-
ment proved very successful. One additional problem that was en-
countered was a failure of the sample pump. This was repaired by plant
personnel within one hour; since then, the instrument has been very
reliable. Figure 16 shows the signal output from the respirometer.
The original purchase price of the respirometer was $5,200. In addi-
tion, a supply of soda lime is needed to absorb carbon dioxide in the
system. The soda lime requires replacement once every two weeks based
on a respiration cycle of one four-liter sample every hour (Table 4).
TOG Analyzer
The TOG analyzer provided for this project was an Astro-Ecology "Model
1000". The installation of this instrument took about one week and
required connections for sample, water, plant air and a drain, (see
Figure 17).
The TOG analyzer initially suffered from considerable calibration drift
(20-30%/week) requiring frequent recalibration. Several times within a
three-week period, the reaction-chamber output-line plugged. At the end
of this time, the infrared (IR) analyzer gave unstable readings.
The IR analyzer was cleaned and checked out, then (with the cooperation
of Astro Ecology representatives, Palo Alto instrument engineers, and
the U.S. Environmental Protection Agency) the analyzer was modified.
The drain connection was relocated and a new filter was installed prior
to the IR inlet.
Performance of the analyzer improved with approximately 10-20% drift/
week. To maintain this degree of stability, daily cleaning (water
rinse) was necessary.
Unfortunately, because of cumulative delays in making the TOG analyzer
operational, it became necessary to delete the TOG feedforward, control-
loop evaluation.
The purchase price of the TOG analyzer was $10,450. See Table 4 for a
summary of these costs.
49
-------
4 - 20 ma SIGNAL TO COMPUTER
TWISTED SHIELDED PAIR
in
O
SAMPLE^IN
3/4" NON COLLAPSIBLE
TUBING WITH 3/4" MALE
PIPE THREAD FITTING
RESPIROMETER
3/4" WATER LINE (40 PSI MINIMUM
FROM
CHECK
VALVE
PLANT
WATER
SUPPLY
1 1/2" PVC PIPE
TO DRAIN (NON-SUBMERGED)
FIGURE 15. RESPIROMETER SCHEMATIC DIAGRAM
-------
24
22
20
18
16
3 14
r-4
l-l
£ 12
£
o
3 10
SUNDAY 3/10
M3SDAY 3/11
TUESDAY 3/12
8 12 16 20
8 12 16 20
Hour
8 12 16 20
FIGURE 16. BADGER RESPIROMETER PERFORMANCE IN mg/LITER/45 MINUTES
-------
Plant Air (25-35 PSI)
10
IOC
4-20 ma Signal to Computer
2 Wire7 Twisted and Shielded"
ANALYZER
Sample Line
Water (40 PSI max)
Drain
Drain #2
t I
FIGURE 17. SCHEMATIC DIAGRAM TOC ANALYZER INSTALLATION
-------
COMPUTER SYSTEM
The computer system at Palo Alto was an IBM System/7, with 16K words of
main storage and 2.5 million words of moving head disk storage. Addi-
tional equipment included a teletype for input and output, a magnetic
tape drive, and a keypunch/card reader. The process I/O included 32
analog inputs, 80 digital inputs, and 32 digital outputs. (See Figure
18).
The installation of the computer hardware was performed by IBM personnel.
The City of Palo Alto had to provide the appropriate electrical power
(220 volts AC at 4.6 KVA) and the proper type of IBM connector. In
addition, a solid ground connection was required, which was also used by
the plant instrumentation. Upon completion of these tasks, the computer
system was operative.
To complete the computer installation, both process measurements (analog),
and equipment/alarm status (digital) had to be wired into the computer.
This was done by parallel connection from panel instrumentation (existing)
to screw terminals in the computer. The total effort of City personnel
to perform these tasks was one man-month.
The system software was based around the Application Module Library
(AML/7), which is a standard IBM product. This software routinely takes
care of scanning, alarming, engineering units conversion, and scheduling
of control and data-management programs on any one of eight clock
frequencies. In this case, 6 seconds, 30 seconds, 1 minute, 2 minutes,
30 minutes, 1 hour, 8 hours, and 24 hours. The basic scanning and
alarming takes place on a six-second cycle.
One additional key program that was provided by IBM, on a custom basis,
was the PAX monitor. This program takes care of multiple partition core
allocations and queuing of programs from disk for these core partitions,
both from program-program requests and from keyboard requests. Thus,
the Palo Alto system has a type of foreground/background processing
capability allowing data management and other types of programs to be
executed concurrently with scan-and-control functions. The development
of this program and an on-line card read program allowed essentially
continuous computer operation.
With the availability of the PAX program, it was possible to begin
testing control strategies on-line. All of the control programs were
written in assembly language (MSP/7 and AML/7). All program assembly/
compilation for this project was performed via a telecommunications link
to an IBM 370 in San Francisco.
Process data were routinely written into disk storage every two minutes.
The disk unit allowed storage of up to eight days worth of data. Once a
week, this data was transferred to magnetic tape for later off-line
53
-------
:.5 MILLION
WORD DISK
32 ANALOG INPUTS
80 DIGITAL INPUTS
32 DIGITAL OUTPUTS-*-
Ui
SYSTEM/7
16 K
MAIN
MEMORY
INCREMENTAL
MAGNETIC TAPE
DRIVE
CARD
READER
TELETYPE
FIGURE 18. COMPUTER CONFIGURATION
-------
analysis. This disk data base was fundamental to the various data
management reports. These included:
Hourly Log
Shift Report
Daily Report
Laboratory Data Entry.
Off-line analysis of the process and laboratory-taped data was performed
on an IBM/370, with all analysis programs written in FORTRAN IV. A
summary and brief description of all programs provided is shown in Table
5.
Computer system failures usually were of two types: fatal and non-
fatal. A fatal failure would either completely stop the system or
prevent writing of data to disk; problems of this type included disk
failure, memory failure, or teletype failure. Non-fatal problems only
required downtime to correct the problem; they did not interfere with
normal data collection and control. Examples of this type of failure
were analog input, digital input, process interrupt, and magnetic tape
failures. Table 6 shows a summary of the computer system failures that
occurred during this study.
The most pronounced failure that was observed was that of the disk
system. Periodically, it would "stall" and fail to record process data.
This condition was not obvious to plant personnel and often would go
undetected for several hours. The problem was apparently due to some
marginal voltages within the computer, 'and has been rectified.
Another problem that still has eluded repair was that of the magnetic
tape system. It occasionally writes data incorrectly, and this malfunc-
tion is usually not discovered until the tape is processed by the off-
line analysis programs. This usually resulted in a loss of either
process or laboratory data. Not all of these incidents have been
recorded.
The purchasing costs of computer hardware of the size and capability
described above would range from $60,000 to $140,000. To that, add
contract maintenance which would be in the range of $100-$500 per.month.
A possible alternative to contract maintenance is on-call maintenance
which would be between $15-30 per hour, plus expenses and parts. If
leasing arrangements are available, they would run between $1400-$4000
per month and would normally include all maintenance and spare parts.
Table 7 shows a summary of computer costs.
55
-------
1057 & 1056
Table 5. PALO ALTO COMPUTER PROGRAMS
AUTOMATIC PROGRAMS
1. SCAN - performs all scanning and conversion to engineering units on a 6-second cycle.
This program resides in core at all times and uses data from the SCAN table
(i.e., table driven).
2. LIMIT CHECK & ALARM - performs limit checking and alarming on high or low limit
conditions. This program also uses data in the SCAN table.
3. DISK WRITE - writes all process data to disk every two minutes. This data is later
retrieved by the magnetic tape program or the report programs.
4. LOG - prints a log of all process variables that are enabled on the teletype every
one hour. This frequency is changeable, but for convenience has been set to
one hour.
5. SCAN UPDATE - enables all analog points at midnight every night. This is to insure
continuation of scanning for points that may have been disabled during the day.
6. 8/24 HOUR REPORT - prints a summary report of process variables every 8/24 hours.
This is the same program as REPORT, but with default values.
7. MONITOR - performs scheduling of programs from disk, in response to either keyboard
requests or program requests.
8. DO CONTROL (C001) - the DO controller runs on a one minute cycle and as implemented
uses proportional plus integral action. A four-point polynomial filter is
Included which also calculates the first derivative.
9. MLSS CONTROL - (C004) - the MLSS control Is essentially the same as the DO control
except it runs on a 30-minute cycle, and presently uses only proportional
action.
10. DO/RAS CONTROL (Cf)05) - this program runs on a 30-minute cycle and calculates the
necessary change in the return activated sludge rate.
11. RESPIROMETER CONTROL (C005) - this program runs on a 30-minute cycle, and using the
respirorceter reading, calculates the necessary change in the RAS rate.
ON DEMAND PROGRAMS
1. KEYBOARD UTILITY - is a collection of short programs to get/put data into the SCAN
tables, enable points, change setpoints, and dump/patch core.
2. CARD READ - raads object cards (programs produced by the host computer) into pre-
assigned areas on desk. Once the program is on disk, it can be catalogued
using the DIRECTOR program.
3. DIRECTOR - establishes a name/number correspondence between programs and disk area.
Once the program is catalogued, it can be executed either by keyboard request
or program request.
4. MAGNETIC TAPE WRITE - writes process and laboratory to magnetic tape. In both cases
an entire day's worth of data is written each time a vrite request is given.
5. DISKLIST - writes data from disk to the teletype. The operator specifies the time
and points of interest, and then an hour's worth of data is written.
6. LAB - reads and writes data from the teletype to the disk laboratory files. Lab data
is entered for a particular day and hour (hour 23 being composite data).
7. AIR - prints out on the teletype the value of each air blowing rate and each DO meter
in the secondary aerators.
8. SOLIDS - is ar. offline program that uses keyboard entered data to calculate centrifuge
performance. This program is used primarily for polymer evaluations.
9. CALCULATOR - is a:> algebraic type of calculation program. Expressions are equated;
then, any combination of add, subtract, multiply, and divide calculation can be
performed on these variable and printed out.
56
-------
Table 6. COMPUTER SYSTEM FAILURES
Date
11/13/72
10/27/72
12/ 5/72
2/21/73
3/ 9/73
3/19/73
3/21/73
5/26/73
6/ 6/73
6/ 8/73
7/20/73
8/ 5/73
8/13/73
8/16/73
8/28/73
8/29/73
10/24/73
10/24/73
1/11/74
1/21/74
Description
Memory Parity
TTY Motor Relay
Analog Input
Digital Input
Disk
Disk
Magnetic Tape
Disk
Disk
Process Interrupt
Digital Input
Disk
Magnetic Tape
Magnetic Tape
Memory Parity
TTY Motor
Disk
Analog Input
Disk
Disk
Fatal
No
Yes
No
No
Yes
Yes
No
Yes
Yes
No
No
Yes
No
No
Yes
Yes
Yes
No
Yes
Yes
Repair Time
(hours)
1.5
1.6
1.25
3.5
2
3
1.75
1.0
1.5
1.3
2.0
0.5
1.75
1.40
4.0
1.5
0.5
1.75
0.5
0.5
Data Loss
(hours)
5
4
2
3
6
13
3
4
3
4
2
57
-------
TABLE 7
TYPICAL COMPUTER COSTS*
PURCHASE
Computer Cost 460,000-$!A0,000 -(one time)
Maintenance $100-$500/mo. $1200-$6000/yr.
LEASE
Computer $1400-$4000/mo. $17,000-$48,000/yr.
OTHER
Utilities (3-6KVA) $22-$44/mo. $260-$520/yr.
@ 1C/KWH
Supplies (paper,cards) $15-$25/mo. $180-$300/yr.
*These costs are for a system of the configuration shown in Figure 4.6.
This DOES NOT necessarily represent the ideal or lowest cost configuration
necessary to accomplish these functions.
58
-------
SECTION VIII
PERFORMANCE OF AUTOMATED STRATEGIES
In analyzing the data from the various control-alogrithm tests, two
evaluation criteria must be considered. The first criteria is an assess-
ment of whether or not the controller functioned as it was intended.
The algorithms developed here are all basically regulators for maintaining
constant levels of DO, MLSS, or F/M. Thus, time-history examination of
the controlled variable in comparison to a manual test, reveals the
quality of regulation.
Second, and most important, the impact of the controller on plant opera-
tion must be determined. The two major areas of demonstrable benefits
are:
Effluent Quality Improvement
Operating Cost Savings.
Comparisons are made between plant-performance indices developed from
data gathered both manually and automatically in order to quantitatively
measure benefits derived from automatic control.
Comparative data for the controller evaluations was developed in two
manual-test periods. The first, Manual Test I, was performed in the dry
season (April thru October) when the plant was operating in the contact
stabilization mode. This period is used as a reference for the DO and
MLSS controllers which were also tested in the dry season and with the
plant operated in the contact stabilization configuration. Manual Test
II, in the wet season (November thru March) and with the plant in the
conventional secondary treatment configuration, is used to compare
operation with the Air/RAS and Respirometer/RAS controllers. Summaries
of all the test-period averages for important operational parameters are
given in Table 8.
DO CONTROLLER
The intent of the DO controller was to adjust the air flow to the aerators
in the secondary treatment process in response to changes in biological
respiration demands. The mechanism of control was to maintain the DO
concentration in the secondary aerators at a constant value.
Figure 19 shows the time-history results of the DO controller for the
three-day intensive test period. DO was maintained very close to the
1.0-mg/l setpoint most of the time despite very large changes in the air
requirements. Comparison of Figure 19 with Figure 20 (data for manual
test I) shows the wide excursions in DO that resulted from the standard
(i.e., manual) procedure of twice daily scheduled, air-blowing-rate
59
-------
Table 8. AVERAGES FOR OPERATING VARIABLES FOR A 30-DAY TEST PERIOD
Test
MANUAL I
7/9/73 to
8/7/74
DO
9/16/73 to
9/11/73
MLSS
9/16/73 to
10/16/73
MANUAL II
10/28/73 to
11/27/73
AIR/RAS
1/13/74 to
2/12/74
RESPIROMETER/RAS
2/13/74 to
3/12/74
Plant
Flow,
mgd
24.0
23.6
26.0
29.0
26.7
24.7
Plant
Loading,
Ib BOD5/day
31,750
38,100
33,700
42,300
39,500
31,700
Return
Activated
Sludge,
mgd
8.9
8.7
11.0
12.6
11.5
12.8
Mean Cell
Residence
Time, Days
10
10
10
10
10
9
Average
Dissolved
Oxygen,
mg/L
1.29
1.04
1.26
1.02
0.78
0.86
Test
Period,
Days
30
31
31
31
31
28
Season
Dry
Dry
Dry
Wet
Wet
Wet
Operating
Configuration
Contact
Stabilization
Contact
Stabilization
Contact
Stabilization
Conventional
Conventional
Conventional
-------
changes. The superiority of automatic control for regulating to a DO
desired setpoint is thus demonstrated.
It should be pointed out that in the process of following the computer's
DO-controller commands, the operators became adept at anticipating the
air-flow requirements themselves by observing the DO strip chart on the
control panel. Figure 21 shows the Manual Test II intensive results,
and indicate a considerable reduction in DO deviation over Manual Test
I. The operators in effect employed analog man in the loop DO control
during Manual Test II. The operator can therefore perform the control
task himself with proper training and experience; however, the frequent
adjustments in control settings (on the order of once every two minutes
during periods of rapid variations in respiration) are very wasteful of
an operator's time, as well as being very monotonous. Automatic control,
when compared to nearly continuous manual monitoring, is far less costly
and produces better results since the machine will not lose interest in
a dull task.
Benefits
The prime benefit expected of the DO controller was power cost savings
due to reduced aver age- air- supply requirements. Air use is minimized by
maintaining the DO at the lowest level consistent with good effluent
quality. The operating point of 1.0 mg/1 DO for the test period was
selected after consultation with Palo Alto operating personnel. No
exploration to determine the absolute minimum DO level was undertaken.
Table 9 shows the removal efficiencies, broken down by unit process, for
both the DO and Manual I tests. Of primary interest are the secondary
process results since that is where the major impact of the DO controller
should be. Direct comparison of the mean of the secondary process
removal efficiency must be tempered by statistical considerations,
however, the standard error of the mean estimates, O^, given in Table 9
is:
a -2 (21)
m
where n is the number of days for which the mean efficiency is calculated
and a the standard deviation of its removal efficiencies.
At the 95% confidence level, for the differences between mean removal
efficiencies, only the secondary TOG removal efficiencies show statisti-
cally significant differences, of approximately 13% better than for the
manual period when compared to automatic DO control. Since the other
removal efficienceis BOD5, COD and SS are all higher for the DO
controller, however, one might conclude that there is a definite improve-
ment in net efficiency for secondary treatment with the DO controller.
61
-------
12,000 -
10,000
£
u
8,000 -
6,000 .
4,000 .
2,000 -
12
SUNDAY
9/9/73
6 12 18
MONDAY
9/10/73
DATE-TIME OF DAY
12
TUESDAY
9/11/73
18
0.0
FIGURE 19. DO CONTROLLER: DISSOLVED OXYGEN AND AIR FLOW VS. TIME
-------
CO
12000
10000
8000
£
o
en
3" 6000
1
Dtf
t t
4000
2000
A
_ xx ' \ >^-> DISSOLVED OXYGEN
'" \ ' \
1 * ! \
/ \ i \
/ * ' \
i \ ' \
1 \ ' i
' \ ' \
\ i *
' \ ' \
1 \ ! \ y^-»AIR FLOW
' ^ 1 » /
- 1 \ / t . /
; \ '\ ' \
' * /* '
' X / \ 1
' \' ^''
i * ; x'--i
;' '
/ i i \
i \ i \ -
1 ' ' \
' i / \
» / *
i i i
t ' '
i / \ /-
» < ' /-'
\ /v ' 1 /
- vy
1 ' 1 > f t 1 1 *
6 12 18 0 6 12 18 0 6 12 18
SUNDAY MONDAY TUESDAY
8/5/73 8/6/73 8/7/73
f- jo w t- L
9 o o b b c
DISSOLVED OXYGEN CONCENTRATION, mg/1
DATE-TIME OF DAY
FIGURE 20. MANUAL TEST I. DISSOLVED OXYGEN AND AIR FLOW VS. TIME
-------
12,0001-
12
SUNDAY
11/25/74
18
6 12 18
MONDAY
11/26/74
DATE-TIME OF DAY
12
TUESDAY
11/27/74
18
FIGURE 21. MANUAL TEST TT: DTSSnT.VFfl
Axm ATP PTOTJ we
-------
If the four measures of waste removal efficiency - SS, BOD_, TOC and
COD - are themselves averaged, the net improvement with automatic DO
control is 7% relative to Manual Test I.
Figure 22 and 23 are log-normal probability plots of secondary effluent
BOD5 and SS concentrations. The DO controller results reveal a very
small mean increase in effluent BOD5 over the manual results. There is
also slightly more dispersion in the BOD_ for DO control. For suspended
solids, the DO controller produced a significant improvement in the mean
(30 mg/1, as opposed to 40 mg/1 for the manual test) with practically
the same dispersion.
Since Table 8 indicates that the conditions of the DO and Manual I tests
were very nearly identical except for plant loadings one might conclude
that there was a measurable improvement in secondary treatment effluent
quality. Given the tighter control of closing the loop and some search
for the optimum DO level, it is probable that effluent quality could be
further improved.
Table 10 lists the results of the primary areas for significant operating
cost savings for all control periods. Only air-compressor power costs
are really applicable to the DO controller since the RAS pumping rate
was constant and also nearly the same as for the Manual 1 test. Air use
is normalized by secondary treatment BOD5 loading. Reasonable estimates
of yearly average BOD,, loading and plant flows are employed to find
total material and power consumption. The power costs for air supply
are developed below.
No separate direct measure of power use was available on the Palo Alto
plant's motor drives for air. A reasonable estimate of the cost of
providing air can, however, be determined knowing peak capacities,
and motor power ratings, P . Then, with the following assumptions:
UiclX
Motor efficiencies, n» are about 90%
A linear relationship exists between compressor or pump output
and power consumption
Power costs, p , at Palo Alto are about Ic/KWH.
The power cost per unit output, p, can be expressed
p P
6 "« (22)
Relevant numerical values for the air power cost per unit output are
presented in Table 10.
65
-------
Table 9. REMOVAL EFFICIENCIES OVER A 30-DAY PERIOD
A. Modified Contact Stabilization
Test
MANUAL I
DO
MLSS
Unit
Primary
Secondary
Plant Total
Primary
Secondary
Plant Total
Primary
Secondary
Plant Total
Std deviation of removal
a.ff X r*-f onr-w
Mean efficiency
SS
51.4
46.3
77.4
47.7
52.8
78.1
47.7
38.3
75.4
BOD
22.9
83.9
87.4
25.8
84.2
84.6
25.3
83.9
84.4
TOC
26.1
53.0
66.1
20,0
59.8
66.7
22.4
50.5
62.4
%
COD
33.6
63.1
75.1
32.5
63.6
74.6
35.6
58.4
72.9
Days
of
data
30
31
31
Standard error of mean, %
SS
11.6
2.1
22.4
4.1
6.3
1.2
12.3
2.2
22.3
4.0
8.0
1.4
11.0
2.0
26.3
4.7
6.3
1.1
BOD5
12.0
2.2
4.5
0.8
3.2
0.6
19.8
3.6
7.5
1.3
5.8
1.0
22.4
4.0
7.5
1.3
9.5
1.7
TOC
12.7
2.3
7.6
1.4
7.0
1.3
7.9
1.4
8.4
1.5
7.3
1.3
10.7
1.9
13.3
2.4
8.6
1.5
COD
10.9
2.0
9.0
1.6
4.9
0.9
11.4
2.0
10.3
1.8
5.2
0.9
16.1
3.0
13.4
2.4
6.9
1.2
Equipment in service
4 Primary Clarifiers
3 Aerators
3 Secondary Clarifiers
1 Sludge Storage &
Reaeration Basin
4 Primary Clarifiers
3 Aerators
3 Secondary Clarifiers
1 Sludge Storage &
Reaeration Basin
4 Primary Clarifiers
3 Aerators
3 Secondary Clarifiers
1 Sludge Storage &
Reaeration Basin
-------
Table 9. (continued) REMOVAL EFFICIENCIES OVER A 30-DAY PERIOD
B. Completely Mixed Aeration
Test
MANUAL II
(analog man in
the loop DO
control)
AIR/RAS
RESPIROWETER/RAS
Unit
Primary
Secondary
Plant Total
Primary
Secondary
Plant Total
Primary
Secondary
Plant Total
Efficiency variance,
Mean efficiency
SS
45.4
58.6
79.8
54.5
49.5
79.6
52.6
63.5
83.8
BOD5
9.1
84.2
81.5
20.0
83.4
87.6
32.4
84.2
91.9
TOC
20.4
67.7
71.6
34.8
59.2
71.3
38.9
63.5
75.3
*
COD
27. 6
64.4
76.9
35.4
54.6
75.2
37.9
65.2
79.1
Days
of
data
30
30
26
Standard error of mean. %
SS
19.0
3.5
27.7
5.1
13.5
2.5
10.1
1.8
25.1
4.6
9.4
1.7
20.1
3.9
19.7
3.9
6.2
1.2
BOD5
11.5
2.1
11.0
2.0
11.7
2.1
14.3
2.6
5.8
1.0
6.0
1.1
16. "5
3.3
7.7
1.5
4.2
0.8
TOC
17.8
3.2
12.6
2.3
9.1
1.7
12.3
2.2
12.4
2.3
7.3
1.3
' 16.4
3.2
15.8
3.1
8.5
1.7
COD
14.4
2.6
13.7
2.5
6.6
1.2
1.7
13.2
2.4
7.9
1.4
3.1
11.0
3.3
5.8
1.1
Equipment in service
3 Primary Clarifiers
4 Aerators
4 Secondary Clarifiers
2 Primary Clarifiers
4 Aerators
4 Secondary Clarifiers
3 Primary Clarifiers
4 Aerators
4 Secondary Clarifiers
-------
00
z
o
50
45
40
35
30
25
20
H
| 15
o
u
in
a
o
«
g
10
b,
CK
0.2
t
j
i i i
i i i
10 20 30 40 50 60 70 80
CUMULATIVE FREQUENCY, %
90
95
99
99.8
FIGURE 22. DRY SEASON TESTS: SECONDARY EFFLUENT BOD CONCENTRATION VS.
LOG NORMAL FREQUENCY DISTRIBUTION
-------
vo
O
E-i
bJ
O
Z
O
CJ
(/I
O
M
O
03
Q
w
CO
p
LO
H
2
tb
u
Q
«
O
w
CO
O MANUAL I
DO
10 _
6-
0.2
20 30 AO 50 60 70 80
CUMULATIVE FREQUENCY, Z
90 95
99
99.8
FIGURE 23. DRY SEASON TESTS: SECONDARY EFFLUENT SUSPENDED SOLIDS
CONCENTRATION VS. LOG NORMAL FREQUENCY DISTRIBUTION
-------
Table 10. TEST PERIODS' OPERATING COST COMPARISONS
Yearly Costs Based on These Yearly Averages:
Aerator BOD. Load « 35,000 Ib/day
Plant Flow =26 MGD
Modified Contact Stabilization
Test
Air
ft
BOD£
in primary*
effluent
Yearly
cost, $
Manual I
no DO control
Digital (man in the
loop) DO control
MLSS no DO control
Completely Mixed Aerator
Manual II
analog man in the loop
DO control
AIR/RAS
digital man in the loop
DO control
RESPIROMETER/RAS
digital man in the loop
DO control
438
377
507
265
274
419
38,631
33,251
44,717
23,373
24,166
26,956
MAX
Pe
600 hp
12,000 SCFM
0.01 $/KWH
Cost Factor
6.9 X 10~6 $/ft.3
70
-------
Comparing the DO cost figures with Manual I figures yields dollar cost
differential on a yearly basis of $5,380. The reduced air use represents
an 11% savings and is a reliable number.
MLSS CONTROLLER
The MLSS controller attempted to regulate the MLSS concentration in the
secondary treatment aerators to a constant value. The MLSS control was
a interim algorithm intended for use in cascade control in other
algorithms. The MLSS control was tested, therefore, primarily for check
out of the MLSS algorithm performance.
Figure 24 is a time-history of MLSS and RAS for the MLSS controller's
intensive test period. The Manual I results are illustrated in Figure
25, although the MLSS values shown are suspect due to some difficulties
with the solids concentration meter during this period. Manual Test II
results in Figure 28 while not directly comparable reveal a more probable
diurnal variation in the MLSS without MLSS control. Solids levels in
the aerators tank were maintained nearly at setpoint except during
periods of low plant flow. One reason for poor control at low plant
flow was because,,the plant's design imposed a low RAS pumping limit of
8.0 MGD (0.03 Mm /day). The controller setpoint was 1500 mg/1, and it
can be seen that the majority of the natural MLSS excursions were in the
high direction corresponding to periods where the RAS rate was at its
lower limit. For low plant influent flows (night and early morning),
the 8.0 MGD (0.03 Mm /day) RAS rate was too high for the desired solids
level so that there was an uncontrolled accumulation of solids in the
aerators.
During the MLSS control test, a floating scum and poor settling charac-
teristic developed with the plant operating in the contact stabilization
configuration. Table 9 provides a comparison of MLSS-test-removal
efficiencies with the Manual I values. All measured quantities BOD,.,
SS, TOC, and COD secondary treatment efficiencies during operation
with MLSS control are somewhat poorer than for the corresponding Manual
I results; although, only in the case of SS efficiency do the results
differ by an amount that has at least a 95% chance of being statistically
significant. Figures 22 and 23 illustrate the secondary effluent BOD
and SS. The deterioration in the settleability of the sludge forced a
change in the plants contact stabilization configuration to the plant's
original design (completely mixed configuration) for the rest of the
control studies and probably produced the decrease in plant performance.
AIR/RAS CONTROLLER
The Air/RAS controller was one of the forms of F/M regulation imple-
mented. It was the intent of these controllers to regulate the instan-
taneous F/M value such that it was at or below a set value. The dif-
ferent forms of F/M control were based on the means of measuring food-
uptake-rate. For the Air/RAS controller, food uptake was implied from
71
-------
20
16
O
<
z
as
2,000
MLSS
12
SUNDAY
10/14/73
18
6 12 18
MONDAY
10/15/73
DATE-TIME OF DAY
1,500
12
TUESDAY
10/16/73
CO
E
1,000
500
18 0
Figure 24. MLSS CONTROLLER: MLSS AND RAS VS. TIME
-------
20
§
w
a
1"
s
i
2,000
1,500
1,000
500
12
SUNDAY
8/5/73
18
DATE-
12
MONDAY
8/6/73
TIME
18
OF DAY
12
TUESDAY
8/7/73
18
FIGURE 25. MANUAL TEST I: MLSS AND RAS VS. TIME
-------
the secondary process respiration rate as measured by the total air
supplied to the aerators.
The Air/RAS controller had two major tasks to achieve:
Estimate food-uptake-rate from measurements of aeration air
flow
Keep F/M at the setpoint level of 0.33 days" .
Figure 26 illustrating actual and estimated food uptake indicates that
the first task was accomplished successfully. Actual food uptake is
taken as the product of primary effluent BOD,, concentration and the
volumetric plant flow (assuming neglible soluble BOD,, in the effluent) .
Estimated food uptake was calculated using air flow rate in the equation
developed in Appendix Section B.2. It is apparent from Figure 26 that
if the air flow rate is used in this manner, it provides an excellent
respirometry measure of plant BOD,, loading.
Figure 27 and 28 are time-histories of RAS and the resulting MLSS in the
aerators for, respectively, the Air/RAS and Manual Test II intensive
periods. Using the actual food uptake (calculated as described above)
and MLSS measurements, F/M time-histories for the two intensive test
periods are plotted in Figure 29. The F/M ratio, U, as used here is:
(V +V ) Xf
a c v
where S is the primary effluent BOD,, concentration, X is MLSS concen-
tration?6and the other terms are defined in the Abbreviations and Symbols.
Both F/M time histories exhibit considerable variation about the desired
set-point value. This is a result of large and rapid variations in food
loading, and therefore, in food uptake, compared to the small changes in
MLSS. Figure 27 shows that the Air/RAS control algorithm attempted- to
vary the MLSS over3the entire RAS pumping range of 20 MGD (0.075 Mm /day)
and 8 MGD (0.03 Mm /day). That pumping range was not sufficient, however,
to completely overcome the large concentration inertia inherent in this
system because of the large mass of microorganisms in the aerator tanks.
There was, in any event, some improvement attributable to the Air/RAS
controller since the late morning peak in F/M, apparent in the manual
results, was eliminated. The peak occurred as a consequence of a sharply
increased flow which washes out the aerator solids, while at the same
time transporting into the aerator a large new quantity of food material.
The Air/RAS controller was able to compensate to a limited extent by
drawing on the sludge that had accumulated in the clarifiers during the
low RAS flow the previous night.
74
-------
40,000 |-
30,000
Ul
20,000
10,000
12 18 0 6 ' 12"' 13
SUNDAY MONDAY
2/10/74 2/11/74
D A T E - T I M K OF DAY
12
TUESDAY
2/12/74
18
FIGURE 26. AIR/RAS CONTROLLER: ACTUAL AND ESTIMATED FOOD UPTAKE
-------
20 -
. 16
3
« 12
8
1
I
I
I
I
I
2,000
I RAS
12
SUNDAY
2/19/74
18
6 12 18
MONDAY
2/11/74
DATE-TIME OF DAY
12
TUESDAY
2/12/74
1,500
eo
e
1,000 5JJ
500
18
FIGURE 27. AIR/RAS CONTROLLER: MLSS AND RAS VS. TIME
-------
20
16
Q
O
Z
q
a 12
o
Q
_J
O
F-
<
£ 8
u
u:
4
0
_
^- RAS
V
/
' \ '
^-----^ .-MLSS / \ 1
"\ -x ^"^-- ^
N.^x'' "x ~~ \ / \ 1
t 1 1 1 1 1 I 1 If 1 1
2000
1500
^
E
1000 M-
00
si
500
r>
12
SUNDAY
11/25/73
18
12
MONDAY
11/25/73
18
0
12
TUESDAY
11/27/73
18
D A T E - T I M E OF DAY
FIGURE 28. MANUAL TEST II: MLSS AND RAS VS. TIME
-------
oo
MANUAL TEST II
AIR/RAS CONTROLLER
RESPIROMETER/RAS
CONTROLLER
DAY-TIME OF DAY
FIGURE 29. COMPARISON OF AMNUAL VS. AUTOMATIC CONTROL OF F/M
-------
The clarifier storage potential was not sufficient, however, to meet the
prolonged, high, daytime food demands as can be seen by the excursions
of F/M above setpoint. Provision for additional, aerated, sludge storage
is necessary to implement a full-time F/M ratio controller adequately,
as is discussed in the chapter on algorithm design. Separate sludge
storage, however, requires that more detailed consideration be given
such process variables as sludge age, wasting rate control, and clarifier
sludge accumulation. Answers to these questions could not be adequately
furnished by this demonstration, and the previously mentioned difficul-
ties with separate sludge storage in the contact stabilization configura-
tion were a consequence.
Reference to Table 9 for comparison of the secondary treatment efficien-
cies from the Air/RAS comparison to the Manual II test results reveals a
drop for three of the four measured efficiencies with Air/RAS control.
Only BOD_ removal efficiencies are close enough to be considered statis-
tically the same.
Figure 30 and 31 illustrating absolute values of secondary effluent BOD
and SS concentrations indicate much less variation in mean removals
between Air/RAS and Manual II than might be expected from the secondary
removal efficiency comparison. In a similar vein, the overall plant
removal efficiencies are practically the same for TOC, COD, and SS,
while BOD,, is significantly better for the Air/RAS controller.
A probable explanation for the anomaly of low, Air/RAS secondary removal
efficiencies is the relatively low, average, secondary unit loading for
that period as shown in Table 11. For a given, average, food to micro-
organism ratio, the average secondary effluent quality in absolute terms
is fixed by biological activity constraints and is reasonably constant.
therefore, if the influent contains less food material (i.e., lower
loading), the effective efficiency is reduced. During the Air/RAS test
period, there was above average removal efficiency for all materials in
the primary treatment while in the Manual II period the primary efficien-
cy is below average. The result was an across-the-board, lower, relative
secondary unit loading for the Air/RAS period which, for the reasons
cited above, could well account for lower observed removal efficiencies.*
Overall, the removal efficiency of the Air/RAS form of F/M controller
was apparently slightly worse than for the comparable manual period.
There is, however, some question as to the finality of this conclusion
for the following reasons:
*the earlier efficiency comparisons for the dry season tests are more
reliable since loading differences between tests were less, and were
not uniformly either higher or lower for the four measured quality
variables.
79
-------
oo
o
to
O
3
o
o
w
U.
U
s
Q
§
U
a
t/i
90
80
70
60
50
40
30
20
10
MANUAL II
O AIR/RAS
- -£s RESPIROMETER/RAS
n
10 20 30 40 50 60 70 80
CUWLATIVE FREQUENCY, 2
90
95
99
99.8
FIGURE 30. WET SEASON TEST: SECONDARY EFFLUENT BOD CONCENTRATION
VS. LOG-NORMAL FREQUENCY DISTRIBUTION
-------
oo
d 90
|>80
z 70
o
E 60
2
g 50
§40
to
Q
30
c
CO
g
20
t/3
IT.
H
W 10
Q
§
U
0.2
MANUAL II
--O- AIR/RAS
.- RESPIROMETER/RAS
_l J J 1_J_... L_
10 20 30 40 50 60 70
CUMULATIVE FREQUENCY, %
80
90
95
99
99.8
FIGURE 31. WET SEASON TEST: SECONDARY EFFLUENT SUSPENDED SOLIDS
CONCENTRATION VS. LOG-NORMAL FREQUENCY DISTRIBUTION
-------
A large variation in secondary treatment loadings between test
periods that could adversely affect Air/RAS results
Palo Alto Plant design constraints on implementation of the
Air/RAS controller did not allow adequate, separate, sludge
storage necessary for the controller to maintain a really
tight F/M
Table 11. AERATOR LOADING FOR THIS STUDY'S SIX TEST PERIODS
3
Test
Aerator loadings, lb/1000 ft day
SS BOD TOG COD
Manual I
DO
MLSS
Manual II
Air/RAS
21.9
18.9
20.1
18.5
15.3
34.1
39.3
35.0
38.4
31.6
Respirometer/RAS
15.7 21.43
23.9
21.4
21.8
17.5
13.0
12.3
62.9
58.9
55.8
52.3
41.2
42.2
Further testing is needed before dismissing the possibility for effluent
quality improvement using Air/RAS control.
Table 10, reveals the yearly dollar aeration cost for Air/RAS as similar
to that for analog man in the loop DO control (Manual II). Air usage,
for practical purposes, was the same for both tests. As mentioned in
the discussion of the DO controller results, however, the operators
effectively maintained a constant DO level during the Manual II test
without computer commands. The original, fixed-schedule, air-blowing
rate of Manual I was not followed since the compressor power-cost savings
attributable to DO had already been demonstrated.
RESPIROMETER/RAS CONTROLLER
This variation of F/M regulation obtained a direct measurement of oxygen
uptake (respiration rate) from a sample of aerator mixed liquor and,
from that measurement, inferred the food loading in the secondary process.
RAS flow was then set based on the suspended solids level necessary to
maintain an instantaneous F/M value at or below the desired set-point
value of 0.33 days
Figure 32 illustrates results for the first performance task of the
Respirometer/RAS controller, estimating food uptake. Here, as in the
Air/RAS discussion, actual food uptake is represented by the product
82
-------
of primary effluent BOD concentration and volumetric plant flow.
Estimated food uptake was calculated from the respirometer's oxygen
uptake reading according to the formula developed in Appendix B.5.
Diurnal variations of the same periodicity occured in both actual and
estimated food uptake, but the estimate based on respiration rate lags
the actual uptake and is also attenuated in amplitude. Part of the lag
is attributable to the one-hour sample-processing time of the respiro-
meter. The remainder of the lag, plus the amplitude attenuation, are
probably attributable to the following:
Transport lag within the aerators - Less than theoretically
perfect mixing causes a lag between waste concentrations at
the influent point versus the effluent point where respiro-
meter sample was taken.
Biological uptake lag - Actual biological oxidation of material
occurs only after the occurrence of all preceding lags
associated with diffusion of substrate into the cell and
conversion of nonsoluble materials to usable soluble substances.
This process also has an averaging effect that attenuates peak
variations in substrate utilization when compared to food-
input variations.
An interesting implication of the less variable food utilization (when
compared to aerator loading) for fully mixed operation is that there is
probably less necessity for tight, instantaneous, F/M control based on
food loading. If F/M control based on utilization is considered instead,
much less diurnal variation would be observed since the volume of bio-
logical processes tend to smooth out the food loading peaks to some
extent. Of course, there still are significant remaining variations in
F/M, even based on actual food utilization; therefore, F/M control is
still a desirable objective.
Figure 33 shows the RAS flow and resultant MLSS for the Respirometer/RAS
intensive test period. Note that there were comparatively modest changes
in MLSS. As mentioned in the Air/RAS controller results, lack of suf-
ficient sludge storage capacity and limitations on RAS pumping rates
(especially the low limit which prevented some additional accumulation
of sludge in the clarifiers at night) made improved MLSS control impos-
sible.
Resultant diurnal variation in F/M for the Respirometer/RAS controller
is compared to Manual II and Air/RAS results in Figure 29. The sludge
retention time of the secondary process was changed during the respiro-
meter/RAS control evolution because of the demands by the plant's thick-
eners for less wasting of the mixed liquor. This change increased the
reactor clarifiers solids inventory and affected the F/M set-point.
Thus1while the computer was set to control at a set-point of F/M «= .33
day" , the plant actually operated a lower average F/M as shown in
83
-------
40,000
30,000.
20,000
00
CL,
3
a
10,000
12
SUNDAY
3/10/74
18
6 12 18
MONDAY
3/11/74
DATE-TIME OF DAY
12
TUESDAY
3/12/74
18
FIGURE 32. RESPIROMETER/RAS CONTROLLER: ACTUAL VS. ESTIMATED FOOD UPTAKE
-------
Figure 29 and did not control to set-point. The F/M ratio was kept
below setpoint at all times, as was desired. Also, as was the case with
the Air/RAS, the late morning peaks in F/M on Monday and Tuesday were
essentially eliminated.
The point of keeping F/M constant was to reduce the diurnal variability
of effluent quality. Listed below are bi-hourly means and standard
deviations of secondary effluent concentrations of the quality measure-
ments for the 3 day intensive test periods. The relative variability is
the standard deviation divided by the mean.
Three Day Intensive Test Results for Secondary Effluent
Respirometer/RAS Manual II
standard relative standard relative
mean deviation variability mean deviation variability
SS,mg/l 31.3 9.4 30% 20.3 7.4 37%
BOD,mg/l 12.1 4.1 34% 8.7 4.2 48%
TOC,mg/l 18.4 2.9 16% 19.6 3.5 18%
COD,mg/l 72.4 9.8 14% 58.8 10.0 17%
In all cases except SS, the absolute standard deviation in daily ef-
fluent quality is less for the Respirometer/RAS controller. The rela-
tive variability (standard deviation divided by the mean) is less in
every case for the Respirometer/RAS. Thus, the F/M ratio regulation
does exhibit the expected result of reducing diurnal effluent quality
swings. The benefit of this result is an overall improvement in effluent
quality and removal efficiency.
Table 9 presents the efficiencies for the plant obtained during the
Respirometer/RAS test. Compared to Manual II results for (biological)
treatment, the Respirometer/RAS showed equal results for BOD,., signifi-
cantly improved SS removal, slightly better COD, and slightly worse TOC.
In the comparison of Respirometer/RAS to Manual II below a negative sign
indicates decreased performance for the Respirometer/RAS control when
compared to Manual II. The absolute change is defined as the difference
between the percent removal efficiencies of the Respirometer/RAS and the
Manual II. The change relative to the Manual II is the absolute change
divided by the Manual II removal efficiencies.
85
-------
00
2,000
1,500
1,000
to
i
500
12
SUNDAY
3/10/74
12 18
MONDAY
3/11/74
DATE-TIME OF DAY
12
TUESDAY
3/12/74
18
FIGURE 33. RESPIROMETER/RAS CONTROLLER: MLSS AND RAS VS. TIME
-------
Secondary Efficiency Absolute Change Change Relative To Manual II
SS + 4.9% + 8.4%
BOD5 0.0 0.0
TOG - 4.2% - 6.2%
COD +0.8% + 1.2%
These removal efficiencies of the biological process in aggregate
showed no significant improvement over the manual results, but were
achieved for abnormally light loadings in each quantity as indicated
in Table 11. The primary process during the Respriometer/RAS operation
exhibited unusually efficient performance and thus reduced the loading
to the biological reactor. An improved effluent quality occurred during
operation with the Respirometer/RAS controller as shown in Figures 30
and 31. Both BOD,, and SS concentrations in the secondary effluent
showed reduced means, as well as less dispersion, when compared to
Manual II and Air/RAS. Mean values obtained are:
Respirometer/RAS Manual II Air/RAS
BOD5,mg/l 16.5 21 21
SS,mg/l 25 28 31
Furthermore, the total removal efficiencies of the plant when it was
under Respirometer/RAS control (Table 9) were the highest for any test
period for the entire demonstration. Total plant efficiency improve-
ments from Manual II to Respirometer/RAS were:
Plant Total Efficiency, Absolute Change Change Relative to Manual II
SS + 4.0% + 5.0%
BOD5 +10.5% + 12.9%
TOO +3.7% + 5.2%
COD + 2.2% + 2.9%
In total then, there was demonstrable positive improvement in effluent
quality during operation with the Respirometer/RAS F/M controller. The
improvement, however, was probably not related only or even chiefly to
the application of respirometer/RAS control. During this control test,
the changes in the plant wasting, at the request of the City of Palo Alto,
increased the solids inventory in the biological process compared to
that during all other operation. The increased inventory produced
87
-------
significantly lower average operating F/M. The combination of improved
primary performance and the lower average F/M in the biological process
undoubtedly contributed significantly to the observed improved overall
plant performance. While the operation with Respirometer/RAS control
exhibited the smallest variability in the instantaneous F/M, further
work is needed to assess whether this reduced variability in the F/M
significantly contributed to the observed improvement in plant perfor-
mance.
From Table 10 the yearly aeration cost increase of Respirometer/RAS over
Manual II (analog man in the loop DO control) was $3,583. The air
figure has been corrected for the period from February 20 to 27 in which
the DO setpoint was at 2.0 mg/1, and extra air was required compared to
operation at the normal 0.75 mg/1 setpoint. Still, there was a sub-
stantial increase in usage per pound of BOD. loading in the aerator
which caused the aeration cost increase. Operation of the plant at the
significantly lower average F/M of approximately 0.15 gmBOD /gmMLVSS/day
increased the air requirements through increased endogenous respiration
of the sludge mass. A revised net cost increase from Manual II to
Respirometer/RAS test is then only $1,852. (operation at significantly
lower F/M (higher MLVSS) increases air requirements through increased
endogenous respiration of this sludge mass.)
88
-------
REFERENCES
1. Martin, C. F., J. F. Petersack, and R. G. Smith, Palo Alto Wastewater
Treatment Plant Automation Project, May 1974.
2. Wells, C. H., Phase I Report Palo Alto Wastewater Treatment Plant
Automation Project, Process Control Descriptions, Report for Calif-
ornia State WQCB by Systems Control, Inc., May 1973.
3. Petersack, J. F. and C. F. Martin, Phase I Report Palo Alto
Wastewater Treatment Plant Automation Project Task 2; Experiment
Design, prepared for State of California Water Quality Control
Board by Systems Control, Inc., July 1973.
4. Petersack, J. F., R. G. Smith, J. J. Ogan, Palo Alto Wastewater
Treatment Plant Automation Project Task 3; Development of Meth-
odology, Report for State of California Water Quality Control Board
by Systems Control, Inc., February 1974.
5. Operation and Maintenance Manual. City of Palo Alto Water Quality
Control Plant, November 1971.
6. American Public Health Association, Standard Methods for the
Examination of Waste Water - 13th Edition, 1971.
7. Metcalf & Eddy, Inc., Wastewater Engineering. McGraw-Hill Book
Company New York 1972.
8. Hawkes, H.A., The Ecology of Waste Water Treatment, Macmillan
Company, New York 1963.
9. Iroshoff, Karl, W. J. Miiller, and D. K. B. Thistlethwayte, Disposal
of Sewage and Other Water-Borne Wastes, Ann Arbor Science Publishers,
Inc., (Ann Arbor) 1971.
10. Bolton, R. L., and L. Klein, Sewage Treatment; Basic Principles
and Trends, Ann Arbor Science Publishers, Inc., (Ann Arbor) 1971.
11. Roesler, J. A., The Effect of Automatic Dissolved Oxygen Control
on the Performance of the Activated Sludge Process, Environmental
Protection Agency Report from the Advanced Waste Treatment Research
Laboratory, (Cincinnati, Ohio) 1974.
12. Smith, Robert, Electrical Power Consumption for Municipal Wastewater
Treatment, Environmental Protection Agency Report EPA-R2-73-281,
July 1973.
89
-------
REFERENCES (Continued)
13. Gandy, Anthony F., Jr. and Elizabeth T. Gandy, Biological Concepts
for Design and Operation of the Activated Sludge Process. Report
for the Environmental Protection Agency by Oklahoma State Univer-
sity, Project #17090 FQJ, September 1971.
14. Petersack, J. F., and D. E. Stepner, "Computerized Data Management
and Control of a Secondary Wastewater Treatment Plant." presented
at the International Association on Water Pollution Conference,
(London, England) September 1973.
90
-------
SECTION X
GLOSSARY
BOD- Five-day biochemical oxygen demand, mg/1
COD Chemical oxygen demand, mg/1
DO Dissolved oxygen, mg/1
DO Mean dissolved oxygen
DO 1st derivative at dissolved oxygen
DO 2nd derivative of dissolved oxygen
dF/dt Food uptake rate, mg/1 day"
A
f Error signal
F/M Food-to-microorganism ratio, gm BOD./gm MLVSS/day
K GAIN
K, Microorganism death rate, days
L Fraction of original BOD, remaining in cell material after
BOD, use in cell synthesis
MG Millions of gallons
MGD Millions of gallons per day
MLSS Mixed liquor suspended solids, mg/1
Q Plant flow, MGD
Q Air flow, SCFM
**
Q Oxygen use rate in biological oxidation, SCFM
2
Q RAS flow rate, MGD
R.
Q Waste sludge flow rate, MGD
w
R Respiration rate, mg/1
RAS Return activated sludge
91
-------
S Primary effluent substrate, mg/1
S Aerator substrate, mg/1
S Clarifier substrate, mg/1
c
SCFM Standard cubic feet per minute
SS Suspended solids, mg/1
T Time constant
t real time
U Food to microorganism, day
y Velocity
V Aerators volume, mg
a
V Clarifier volume, mg
V Respirometer sample-chamber volume, liters
WAS Waste activated sludge
X Aerator suspended solids, mg/1
X Clarifier suspended solids, mg/1
x RAS suspended solids, mg/1
Y Mass yield of microorganisms per unit mass substrate consumed
y BOD, mass demand equivalent per unit mass of microorganisms
a Constant in DO equation
A Time change in minutes
6 Mean cell residence time of microorganisms in the secondary
system
92
-------
APPENDIX A
FLOWCHARTS
93
-------
ASSOCIATED DATA STORAGE (ADS) DATA DEFINITION FOR DO/RAS CONTROL
ADS Number
1
2
3
4
5
6
7
8
9-20
Variable
Cl
C2
C3
C4
XR
QRMAX
QRMIN
QTOL
Not used
Definition
Gain terms
SS in RAS
High limit
Low limit
Deadband
QA
-------
FIRST
kGET RAW
VALUE (Z)
AND
INDICATORS
jINITIALIZE
I CONSTANTS
BN - Z
BN1 - Z
BN7 - Z
FILTER
BN»XHAT=G11*BN+G12*BN1+..,+G17*BN7
XDOT="G21*BN-Ki22*BNl-f. . .+G27*BN7
XDDOT-(G31*BN-H;32*BN1+. . .+G37*BN7)*2
/PUTWAY
Gil Filter Coefficients
UPDATE PAST\
VALUES AND \
PUT IN ADS /
DO AND MLSS CONTROL FLOWCHART
95
-------
STATUS
MANUAL
o
I '
LOAD \
CONTROL ]
OVERLAY _/
DISABLE
CONTROLLER
SURE-
MENT ENABLE
(Z)
MANIPU-
LATED VARIABLE
ENABLED?
CONTRO
CONTROL
STATUS
UTO?
CONTROL
STATUS
MANUAL?
ZERO
INDICATORS
AND GO TO
MANUAL
CONTROL
.STATUS "GO TO
AUTO"?
96
-------
TIMER
CONTROL..,.- LAST VALUE CONTROL
CONTROL - PRESENT VALUE CONTROL ^Xl CONTROL,,,;^ YES
DELU2 - CONTROL DEADBAND
C
EXIT
OPERATOR
FOLLOWING
INSTRUCTIONS
97
-------
ERRQR-SETP-BN
NLGAIN-GAIN*(ALPHA+BETA*|ERROR|)
PTERMK1*XDOT
ITERM-K2*ERROR
DTERMK3*XDDOT
DELT-NLGAIN* (PTERM+ITERM+DTERM)
LIMIT
CHECK
OUTPUT
CHANGE
NLGAIN - NONLINEAR TERM
PTERM - PROPORTIONAL TERM
ITERM - INTEGRAL TERM
DTERM «- DERIVATIVE TERM
DELT - DELTA OUTPUT
LOWLIM - LOW LIMIT
HILIM - HIGH LIMIT
OUTPUT-CONTROL-f-DELT
DELU1 - OUTPUT DEADBAND
98
-------
CONTROL-
OUTPUT
-DELU2
AT LIMIT AND
WITHIN TOLERANCE
LIGHT OPERATOR
LIGHT
CHANGE
MANIPULATED
VARIABLE
(CONTROL)
SAVE INDICA-
TORS AND
VALUES IN
ADS
99
-------
ASSOCIATED DATA STORAGE (ADS) DATA DEFINITION FOR DO AND MLSS CONTROL
ADS NUMBER
VARIABLE
DEFINITION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
SETP SETPOINT
GAIN LOOP GAIN
Kl PROPORTIONAL GAIN
K2 INTEGRAL GAIN
K3 DERIVATIVE GAIN
TIME TIME SINCE LAST CHANGE
BN FILTERED VALUE
BN1 PREVIOUS VALUE (n-1)
BN2 PREVIOUS VALUE (n-2)
BN3 PREVIOUS VALUE (n-3)
BN4 PREVIOUS VALUE (n-4)
BN5 PREVIOUS VALUE (n-5)
BN6 PREVIOUS VALUE (n-6)
BN7 PREVIOUS VALUE (n-7)
XDOT DERIVATIVE OF BN
XDDOT SECOND DERIVATIVE OF BN
OUTPUT L
ALPHA
BETA
NOT USED
\ OUTPUT
NONLINEAR GAINS
10O
-------
TOTAL PLANT
FLOW ENABLED?
(A0W)
MESSAGE
DISABLE
DO/RAS
-( EXIT J
MESSAGE
CHECK STATUS
OF MEASURED
VARIABLES
GET MEASURED
VARIABLES
RAW
MLSS VALUE
ENABLED?
(A022)
DO/RAS CONTROL FLOWCHART
101
-------
II - 0.3333
V 7.68
X - A*22
ACFM - A008
V A?10 + A0U
CALCULATE
TOTAL AIR
BL . Cl*ACFM - C2*X - C3
F <(XR*U*V*C*)/BL) - 1.0
LIMIT CHECKS
102
-------
ASSOCIATED DATA STORAGE (ADS) DATA DEFINITION FOR DO/RAS CONTROL
ADS NUMBER
1
2
3
4
5
6
7
8
9-20
VARIABLE
Cl
C2
C3
C4
XR
QRMAX
QRMIN
QTOL
NOT USED
DEFINITION
GAIN TERMS
SS IN RAS
HIGH LIMIT
LOW LIMIT
DEADBAND
103
-------
MEASUREMENT
CHECKS
RESPIROMETER CONTROL FLOWCHART
104
-------
APPENDIX B
DETAILS OF F/M RATIO CONTROLLERS ALGORITHM DESIGN
105
-------
APPENDIX B
Details of F/M Ratio Controllers Algorithm Design
B.I STEADY STATE RAS FLOW TO MAINTAIN TO GIVEN MLSS CONCENTRATION.
A microorganism mass balance around the aerators
(Schematic in Figure B.I) yields
net microorganism
growth in aerators
dX dp
V -j-^ = QDXD - (Q + Q_. + QTI\X + Y^f - K.X V
a dt R R \x XR XW/ a dt d a i
In steady state
a
d
= 0
(B.I)
(B.2)
and for no sludge build-up or depletion in the total secondary system
,,dF
V= Y^r - K./X V + X V \
a dt d\ a a c c/
(B.3)
The right hand side of Equation B.3 is net cell growth in the total
secondary plant volume. Using Equations B.3 and B.2 with B.I yields
0 = QD(XD - X \ - QX + K.X V
XR\ R a/ x a dec
(B.4)
and therefore
Q
1 -
K.X V 1
dec
. QXa J
(B.5)
The quantity K X V /(QX ) is much less than 1.0 (about .01 for Palo
Alto) and can therefore c>e neglected; so that
(B.6)
B.2 RELATIONSHIP BETWEEN FOOrHjPJTAKE"AND AIR CONSUMPTION IN SECONDARY
TREATMENT.
106
-------
AERATOR I CLARIFIER
1
VOLUME,
PRIMARY Q' So
EFFLUENT
I-1
O
~j
V
a. .
AERATION |
AIR OUT|QA
*~~*^^~~~~~*-*^~~~ ^L_-2
X , S , DO
a a
! I
1 + QR - V
Q
^^^^1* »!" ' ^' ^"*
X , S
c' c
R' XR' Sc
Q - Qw> xe, sc
^
SECONDARY EFFLUENT
VOLUME, V
^^^^^^
f RETURN ACTIVATED SLUDGE
V t Qw
WASTE ACTIVATED
AERATION SLUDGE
AIR IN
FIGURE B.I. ACTIVATED SLUDGE PROCESS SCHEMATIC
-------
An oxygen mass balance for biological respiration in the aerators yields
f
(Va + Vc)
(B.7)
where L is the fraction of original BOD^ demand remaining in the bio
mass after cell synthesis, y is the BOD,, mass demand per unit mass of
microorganism cells, and Y is mass yield of microorganisms per unit mass
of food consumed. A microorganism mass balance around the entire secondary
system is
(V + V \ 3*- = YT^ - K ,X (V + V } -
\ a c) dt dt d \ a c/
Qxe)
(B.8)
where X is the average microorganism density, in the entire secondary
system. Since the wasting rate policy is
/V + V ) QX
\ a c/ x c
9 ~ X
(B.9)
Equation B.8 can be rewritten
dt
Y dF _ - _ fa
V + V dt d 0
a c c
(B.10)
On average, whatever control policy is followed, X %X , so Equation
B.10 becomes
i'/J
I
2
(B.13)
108
-------
where
= (TV-Hi)
b = TK,
sin ftot + tan"1 / bTa) Yl
L \a ~ b/JJ
i
2
(a)
(b) (B.14)
T =
,
d c
(c)
For typical operating conditions:
6 = 10 days, K, - 0.05 days , w = days
the ratio of the constant part of Equation B.13 to the amplitude of the
sinusoidal part is about 2 to 1. Therefore, a simplification of Equation
B.13 can be made such that
dF
and
substitution of
6 dt '
c
Equation
V
1
~ V + V
a
B.15
- YyL
c
into
/
ta
dt
B.12
1
8 + ]
c
to give:
\l
l)J
dF
dt
If a mass balance for air in the aerators is developed:
d DO
dt
QA ~ QA - Q0
Ai o °2
(B.15)
(B.16)
(B.17)
and an assumption made about the relationship between Q. and Q.
Ai c
Ki
K
i o 2
then for a constant DO level (i.e. d D0/(dt) = 0)
(B.18)
dF
dt
1
YyL
K,9 +1
d c
Kl QA H
1 A±
HK2
(B.19)
109
-------
50,000 -
40,000
30,000 _
o
S 20,000
c
in
g 10,000
2,000 4,000 6,000 8,000
AIR FLOW RATE, SCFM
Bihourly Data From Manual
Test II Intensive
__ Regression Fit of C Air + C
5.25 Ib/day
6667 Ib/day
SCFM
I
10,000
12,000
FIGURE B.2. REGRESSION CORRELATION OF SECONDARY TREATMENT
LOADING AND AERATION AIR FLOW
-------
The constants K. and K_ relate the amount of air required to put a given
quantity of oxygen into solution. Since the relationship is a complex
function of temperatures, flow rates, bubble size, and agitation; Equa-
tion B.19 is put into the form
f=ClQAi+C2 (B.20)
and GI , c_ are determined empirically by regression (see Figure B.2)
with plant operating data. For Palo Alto in the conventional mode
operation in the wet season
_800
B. 3 RELATIONSHIP BETWEEN FOOD UPTAKE AND SUBSTRATE LOAD IN SECONDARY
TREATMENT
In section B.2, the relationship between food uptake, dF/(dt), and air
use is developed. Substrate loading changes, QS , will not, in general,
result in instantaneous uptake rates. The lag in uptake can be deter-
mined using a substrate mass balance for the aerators:
dS
- Va - (Q + V Sa + Vc
In general, S , substrate concentration in the aerators, is approxi-
mately the same as S , substrate concentration in the clarifier. From
Reference [7], the relation between food uptake, dF/(dt), and substrate
concentration is
,_
dF
dt
so that Equation B.21 becomes
KX S
a a
K + S
s a
, .
(B'22)
dS,
dF
KX _
a , Q
K + S V
s a a
S + QS
a x o
(B.23)
S for proper operation is always much less than K so that the time
constant, Tc , for S changes in the aerator is
o a
a
KX
K + S
s a
a
111
-------
For Palo Alto, realistic values for parameters of Equation B.24 are:
K - 10 days , K = 100 mg/1, X = 1200 mg/1, S % 10 mg/1, Q = 30 MGD
(0.11 Mm /day) and V = 7.2 MG to.027 Mm ). Therefore, T_ K 10 minutes
3. o
a
which means that the time lag between substrate load and uptake is short
enough to be neglected.
Thus, dS /(dt) can be assumed zero in Equation B.21 yielding
Si
«».-8.> f f
a
and since S is a constant fraction, f, of S for a given removal
efficiency
Q So(l - f) = |~|| (B.26)
a
Loading, QS , is thus directly proportional to food uptake, dF/(dt);
which, in turn, as shown in section B.2, is a function of air use in the
aerators.
B.4 AVERAGE FOOD UPTAKE TO MICROORGANISM RATIO AS A FUNCTION OF MEAN
CELL RESIDENCE TIME
Average F/M ratio, U, is defined
dF
U « ^ (B.27)
V X f
a a v
Using the .long _term average of Equation B.ll (i.e. dX/(dt) = 0) and the
fact that X ^ X then
a
'K'+*./\« c/
(B.28)
Y V f
a v
B.5 RELATIONSHIP OF RESPIROMETER MEASUREMENT TO FEED UPTAKE
A mass balance on oxygen in the closed sampling system of the respiro-
meter shown schematically in Figure B.3 is:
/I dF \
R =
-------
SAMPLE LINE
INCOMING MICROORGANISM
CONCENTRATION, X. I
-h*n."
. ,.. . J^^J
r^
MPLE VOLUME
VR
t!
V
1
1
1
1
1
1
1
1
I Q) PRESSURE TRANSDUCER
1
CO SCRUBBER
DRAIN
Sample System Loaded and Operated
for Sanple Time, T.
FIGURE B.3. RESPIROKETER SCHEMATIC
-------
Microorganism mass balances are
dX,
dt
KdXi
(B.30)
for the original cells and
d
- KdXn
for the new calls. If dF/(dt) is assumed constant for the sampling
period, solutions to Equations B.30 and B.31 are
"Kdt
(B.32)
and
X
n ' KX f
d R
Substituting Equation B.32 and B.33 into B.29 and integrating for the
sample period T yields:
-LyYKdTe"KdT
~x
With the simplification, 1 - x, for the exponential e with x small
(B.34)
f [l - LyY] + KdVRXi [l - LyYKdT] (B.35)
or since LyYKdT « 1
R - K V X
d K. i
! -
114
-------
APPENDIX C
SUMMARY OF COMPUTER OUTPUT*
*Adjusted for uniform plant conditions.
115
-------
APPENDIX C.I
MANUAL-I DATA
116
-------
JULY 9 1973 TO AUG 7 1973
DESCRIPTION
TOTAL PLANT FLOW
LOS ALTOS FLOW
MT. VIEWFLOW
P H
O 0 #1
D 0 #2
D 0 #3
D 0 #4
AIRFLOW #1
AIRFLOW #2
AIRFLOW #3
AIRFLOW #4
TH #1 FLOW
TH #1 DENSITY
TH #2 FLOW
TH #2 DENSITY
TH #3 FLOW
TH #3 DENSITY
TH #4 FLOW
TH #4 DfcNSITY
RAS FLOW
WAS FLOW
MLSS
SLUDGE BLANKET
CHLORINE #1 RESIDUAL
CHLORINt FLOW #1
CHLORINE FLOW #2
CHLORINE FLOW #3
CHLORINE #2 RESIDUAL
SULFUR DIOXIDE FLOW
SPARE
SPARE
PROCESS DATA SUMMARY
AVE HIN MAX
24.06 5.59 36.48
SENSOR NOT OPERABLE
SENSOR NOT OPERABLE
7.92 6.69 8.24
0.04 0.0 0.15
0.13 0.0 1.27
0.99 0.57 3.66
1.58 0.00 5.C7
2C00.56 960.13 3064.88
954.30 21.62 1684.69
20O3.95 917.25 2940.63
2094.80 1053.31 2893.50
25.10 0.0 6C.84
5.01 0.40 5.19
13.24 0.0 61.06
4.82 4.62 4.82
5.32 0.0 57.69
2.82 0.0 6.1b
23.69 0.0 61.05
4.85 4.85 4.66
8.88 6.96 25.34
2.43 0.52 3.12
1699.72 321.41 2692.38
0.0 0.0 -0.0
O.C 0.0 O.C
0.0 O.C c.u
0.0 C.O O.C
0.0 0.0 C.O
0.0 C.O O.C
O.C C.C 0.0
O.C C.O O.C
NO VALID DATA
MANUAL PLANT CONTROL
STD UNITS
4.53 MGD
C.27
O.07
0.15
0.35
1.31
260.73
199.47
252.70
288.13
2C.54
0.16
17.89
G.C-4
12.45
2.40
20.37
0.04
3.29
C.27
386. CO
0.0
C.O
O.C
O.C
C.C
C.C
C.C
C.C
MG/LITER
MG/LITEP
MG/LITER
MG/LITER
CFM
CFM
CFM
CFM
GPM
PERCENT
GPM
PERCENT
GPM
PERCENT
GPM
PERCENT
MGD
MGD
MG/LITER
FT
MG/LITER
LB/DAY
LB/DAY
LE/DAY
MG/LITER
LB/DAY
-------
JULY 9 1973 TO AUG
7 1973
LOADING DATA SUMMARY
MANUAL PLANT CONTROL
00
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
AUG
AUG
AUG
AUG
AUG
AUG
AUG -
9
1O
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1
2
3
4
5
6
7
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973.
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
SS(LBS)
SREMOVEDfEFFLUENT
BCOILBS)
XREMOVED|EFFLUENT
TOC(LBS)
XREMOVEDIEFFLUENT
CDDILBS)
XREMOVEDlEFFLUENT
74.8 X
73.6 X
85.3 X
84.6 X
81.9 X
75.4 X
81.2 X
90.9 X
86.9 X
83.7 X
75.8 X
70.5 X
68.6 X
60.3 X
77.9 X
78.3 X
72.7 X
78.9 X
81.1 X
80.6 X
87.8 X
80.6 X
76.2 X
73.8
70.4
80.6
73.0
84.2
83.4
74.5
5475.
7755.
5775.
5441.
6611.
5821.
3832.
3640.
3920.
5607.
5964.
8711.
, 8469 .
8771.
7187.
7446.
8392.
6235.
7415.
6373.
4119.
6427.
7736.
11381.
9466.
10573.
9290.
7378.
7161.
9965.
100.0
86.7
87.6
88.3
94.6
82.9
83.8
91.9
90.6
91.2
86.3
87.2
81.6
85.0
91.4
85.1
83.7
83.3
89.2
88.3
90.0
81.9
85.6
86.9
89.3
87.9
88.8
89.6
88.3
87.1
X
X
x
X
x
X
X
X
X
X
X
x
X
X
X
X
X
X
X
X
X
X
X
x
X
X
X
X
X
X
. 0
4408
4208
4111
1683
3929
3553
2548
3837
3536
5676
4717
5428
3782
3044
3971
4196
4345
3305
2781
2042
3374
4764
5214
3786
4354
3470
3889
4982
*
9
*
*
*
*
*
.
*
4990.
55.9
64.4
66.1
76.2
68.8
64. 0
64.9
63.9
61.0
67.9
52.2
67.0
59.6
52.5
63.8
72.3
57.8
63.1
69.6
68.8
73.4
72.0
68.8
83.6
62.6
59.0
67.2
72.1
73.0
71.5
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
8800.
6531.
7838.
7254.
6010.
5821.
5922.
7886.
9490.
6194.
8844.
7649.
7314.
8588.
8879.
8894.
9790.
9655.
8051.
6566.
4478.
7030.
7125.
8277.
8414.
9951.
7537.
7673.
7854.
8878.
67.5
68.6
71.6
75. C
73.1
70.2
75.9
79.1
80.0
83.3
85.8
73.0
68.5
66.4
76.3
75.7
74.9
73.6
80.0
72.0
71.4
77.4
79.3
74.2
69.4
73.8
83.5
79.0
79.8
75.5
X
%
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
19555
16940
18976
16322
15625
13643
9927
12941
14854
14721
2C772
19122
179C1
15350
14798
17375
17782
17901
21822
17767
13791
15064
16287
19037
20193
18659
16651
16634
16880
20058
-------
JULY 9 1973 TO AUG 7 1973
LOADING DATA SUMMARY
MANUAL PLANT CONTROL
NH3JLBS)
XREMOVED|EFFLUENT
NOZ(LBS)
XREMOVED|EFFLUENT
N03CLBS)
XREMOVFDIEFFLUFNT
PHOS
-------
JULY 9 1973 TO AUG 7 1973
AIRFLOWS IN CUBIC FEET
PLANT AIR CONSUMPTION
ASSUMED COST - $.000095/CF
MANUAL PLANT CONTROL
JULY
JULY
JULY
JULY
JUtY'
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
^HJLY
JULY
JULY
-JUtY-
JULY
JULY
JULY
JULY
JULY
JUtY
AUG
AUG
AUG
AUG
AUG
-AtJG
AUG
9
10
11
12
13
14
15
16
17
18
1^
20
21
22
23
24
25
26
27
28
29
30
31
1
2
3
4
5
6
7
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
AIRFLOW#1
2652753.
2706295.
2413933.
2727619.
2724681.
2750203.
2727329.
2763581.
2930311.
2806847.
2776771.
2829813.
2838729.
2945117.
2942641.
2997731.
2942043.
2954511.
3033717.
2966915.
2846761.
2865529.
3013675.
3030785.
3033989.
3011375.
2994489.
3276707.
3052575.
3035107.
AIRFLOHJ2
1339943.
1395984.
1102778.
1380698.
1378603.
1394967.
1451949.
1160880.
1544034.
1573373.
1677903.
1338812.
1430872.
1607674.
1493985.
1513C04.
1442067.
1411051.
1514040.
1579331.
1568572.
1457704.
1173467.
1245846.
1229986.
1133828.
1155212.
1291274.
1099029.
1078834.
AIRFLOWP3
2804291.
2869241.
2521453.
2863347.
2865183.
2850313.
2795265.
2807237.
2987671.
2831971.
2641155.
27CO923.
2723517.
2846639.
2811275.
2851547.
2777893.
2762645.
2855447.
2843795.
2851751.
3033419.
3105067.
3105115.
3077407.
3047875.
3038314.
33497C1.
3112945.
3063431.
AIRFLOW#4
TOTAL
COST
3232977.
3285297.
2998325.
3255660.
3254859.
3192407.
3096833.
3276585.
2776055.
2969141.
3169867.
3321679.
2939643.
2832617.
2928497.
2963329.
2936967.
2945785.
2991393.
2844743.
2885747.
2905177.
2840401.
2811421.
2848349.
2938947.
2877211.
3187881.
3031857.
3018227.
1CC29964.
10256817.
9036489.
10227324.
10223326.
10187890.
10071376.
10008283.
10238071.
10181332.
10265696.
10191227.
9932761.
10232047.
10176398.
10325611.
10098970.
10073992.
10394597.
102*56784.
10152831.
10261629.
10132610.
10193167.
10189731.
10132025.
10065226.
11105563. .
10296406.'
10195599.
$
$
$
$
$
$
$
S
$
$
$
$
$
$
$
$
$
$
$
$
S
t
$
$.
$
$
$
t
$
S
952.85
974.40
858.47
971.60
971.22
967.85
956.78
950.79
972.62
967.23
975.24
968.17
943.61
972.04
966.76
980.93
959.40
957. C3
987.49
974.39
964.52
974.87
962. 6O
968.35
968.02
962.54
956.20
1055.03
978.16
968.58
TOTAL
86614336.
41165568.
86795648.
90557712.
305133312.
28987.66
-------
JULY 9 1973 TO AUG 7 1973
MONTHLY EFFICIENCY SUMMARY
MANUAL PLANT CONTROL
PRIMARY
SECONDARY
CHLORINATOR
SS
BCD5
TOC
COD
JULY 9 1973
UNITS -
AVE
STC
AVE STD AVE STD AVE
51.4 % 11.6 Z 73.9 Z 8.9 Z
22.9 Z 12.0 Z 87.6 Z 2.9 Z 1
26.1 ? 13.1 Z 65.3 Z' 6.3 Z
33.6 Z 1C. 9 % 75.5 Z 4.4 %
TO AUG 7 1973 RESPIRATION SUMMARY
LBS LOADING / 1000 CUBIC FEET CF AERATOR TANKAGE
SS BOD TCC
21.86 34.05 23.92
4.72 $.0fl 4.20
STD
78.2 Z 6.5 Z
87.4 % 3.3 Z
66.1 Z 7.0 Z
75.1 Z 4.9 Z
MANUAL PLANT CONTROL
CCD
62.92
9.48
-------
APPENDIX C.2
DO DATA
122
-------
to
u>
AUG 12 1973 TO SEPT 11 1973
DESCRIPTION
TOTAL PLANT FLOW
LOS ALTOS FLOW
MT. VIEWFLOW
P H
D 0 #1
0 0 #2
D 0 #3
0 0 #4
AIRFLOW HI
AIRFLOW #2
AIRFLOW #3
AIRFLOW #4
TH «1 FLOW
TH #1 DENSITY
TH #2 FLOW
TH #2 DENSITY
TH *3 FLOW
TH #3 DENSITY
TH #4 FLOW
TH #4 DENSITY
RAS FLOW
WAS FLOW
MLSS
SLJDGE BLANKET
CHLORINE #1 RESIDUAL
CHLORINE FLOW #1
CHLORINE FLOW *2
CHLORINE FLOW #3
CHLORINE #2 RESIDUAL
SULFUR DIOXIDE FLOW
SPARE
SPARE
PROCESS DATA SUMMARY
AVE MIN
MAX
23.57
SENSOR
SENSOR
7.28
0.99
1.01
0.34
1.13
2208.38
1125.60
2280.35
1569.53
1.12
5.45
25.75
5.41
29.98
2.76
0.97
5.71
8.67
1.72
1273.17
425.67
0.0
0.0
0.0
0.0
0.0
0.39
0.0
13.05
NOT OPERABLE
NOT OPERABLE
6.61
0.01
0.10
0.0
0.05
315.20
4.29
181.37
402.25
0.0
0.43
0.0
0.0
0.0
0.0
0.0
0.0
1.60
0.41
896.00
3.70
0.0
0.0
0.0
0.0
0.0
0.0
0.0
NO VALID DATA
37.65
8.11
4.84
5.09
3.04
5.01
3603.63
3025.75
3668.88
3102.25
60.36
5.64
61.06
7.35
60.73
8.94
60.71
5.92
18.57
2.83
2020.06
2214.25
0.0
0.0
0.0
0.0
0.0
13.54
0.0
AUTOMATIC PLANT CONTROL
STD UNITS
4.59 MGD
0.15
0.54
0.56
0.34
0.59
517.16
511.94
534.67
446.15
2.38
0.19
12.06
0.58
12.88
2.09
7.50
0.74
1.19
0.26
196.10
559.73
0.0
0.0
0.0
0.0
0.0
1.52
0.0
MG/LITER
MG/LITER
MG/LITER
MG/LITER
CFM
CFM
CFM
CFM
GPM
PERCENT
GPM
PERCENT
GPM
PERCENT
GPM
PERCENT
MGD
MGD
MG/LITER
FT
MG/LITER
LB/DAY
LB/OAY
LB/DAY
MG/LITER
LB/OAY
-------
AUG 12 1973 TO SEPT 11 1973
LOADING DATA SUMMARY
AUTOMATIC PLANT CONTROL
SS(LBS)
XREMOVEDJEFFLUENT
BOO(LBS)
XREMOVEDIEFFLUENT
TOC(LBS)
XREMOVEDIEFFLUENT
COO(LBS)
XREMOVEOlEFFLUENT
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1
2
3
4
5
6
7
3
9
10
11
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1Q73
1973
1973
1973
1973
1973
1973
1973
1973
1973
197?
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
78.
79.
79.
73.
70.
82.
84.
84.
77.
81.
73.
60.
68.
77.
72.
96.
83.
63.
63.
80.
66.
74.
82.
87.
81.
79.
78.
83.
87.
86.
83.
6 X
0 X
7 X
1 X
5 X
5 X
2 X
5 X
5 X
5 X
1 X
9 X
4 X
6 X
1 X
1 X
2 X
9 X
9 X
9 X
2 X
6 X
0 X
4 X
5 X
1 X
2 X
1 X
8 X
3 X
5 X
6612.
5440.
5921.
7560.
6599.
4409.
4339.
3909.
5865.
5030.
7522.
8782.
7454.
5992.
5469.
1238.
3538.
8601.
9359.
5866.
8385.
4931.
4962.
3568.
6224.
5864.
4471.
4140.
3163.
4572.
5118.
87.6
76.8
84.5
85.2
75.6
90.5
81.7
81.5
87.0
92.6
88.2
86.6
86.0
87.8
79.2
78.7
87.2
90.1
84.3
90.4
82.3
75.8
78.9
79.5
86.0
83.5
68.0
88.0
89.1
91.4
88.1
X
X
x
x
%
x
x
x
X
X
X
X
X
x
x
x
X
X
X
X
x
X
X
x
X
x
X
X
X
$
x
2534.
4519.
4313.
3260.
11240.
4199.
7358.
2985.
2912.
3353.
6519.
4779.
6527.
5505.
8680.
10525.
6132.
4920.
5737.
3034.
5974.
7039.
8110.
9038.
6721.
7400.
8780.
2794.
2704.
2547.
3771.
61.9
67.3
66.7
73.3
56.8
65.6
73.7
65.9
75.3
68.4
67.0
62.8
56.5
68.9
63.6
70.0
58.3
64.8
61.8
68.4
44.9
60.8
73.2
73.2
76.9
74.8
56.2
70.9
70.9
76.1
72.9
X
X
x
X
X
X
X
x
x
X
X
X
%
X
X
x
x
x
x
X
x
X
x
Z
6795.
6695.
6766.
5434.
6812.
6718.
4905.
4975.
4652.
6287.
6477.
7148.
8059.
6179.
5646.
8048.
7862.
7601.
7935.
7484.
7512.
5271.
4449.
5946.
5809.
5864.
7927.
3967.
5515.
5792.
6371.
72.9
76.9
74.4
71.6
77.6
78.1
78.9
74.8
76.6
76.2
75.2
66.2
67.3
65.1
72.1
89.7
73.2
71.4
71.2
72.2
68.9
76.2
78.5
78.2
75.4
71.6
64.8
75.4
81.6
81.0
78.2
X
%
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
%
X
X
X
X
%
X
X
X
17080.
17994.
19665.
17955.
16391.
14695.
13206.
11905.
13753.
15718.
15880.
19197.
18334.
21720.
12879.
7636.
15527.
17802.
20956.
18408.
18867.
13092.
13175.
15460.
16389.
16782.
21341.
11385.
9938.
' 13286.
15563.
-------
AUG 12 1973 TO SEPT 11 1973
LOADING DATA SUMMARY
AUTOMATIC PLANT CONTROL
NH3CLBS)
XREMOVEDlEFFLUENT
N02CLBS) N03(LBS> PHOS(L8SI
XREMOVEDlEFFLUENT XREMOVEDlEFFLUENT XREMOVEDlEFFLUENT
N>
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
SEPT
SFPT
SFPT
SEPT
SEPT
SEPT
SEPT
SEPT
SFi»T
SFPT
SEPT
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1
2
3
4
5
6
7
8
9
10
11
1973
1973
1973
1<373
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
-7.7 %
2.7 X
-5.3 X
-1.3 *
9.0 %
8.4 X
2.2 %
-10.8 %
36.1 %
1.6 %
20.3 %
26.2 %
7.9 X
-5.0 *
1.1 %
15.2 X
11.6 %
14.7 *
16.9 %
25.7 *
18.3 X
0.0 %
0.0 X
20.0 %
33.3 *
13.9 %
6.1 %
15.7 *
17.7 %
22.3 *
9.2 *
5142.
7449.
7126.
9096.
7770.
7116.
5754.
5117.
3944.
7523.
6582.
6331.
7092.
6291.
6210.
7037.
5995.
6401.
6511.
5563.
4891.
2805.
2823.
4361.
5394.
6268.
6301.
5089.
3814.
4503.
6075.
0.0 X
72.2 %
98.2 X
96.2 %
97.5 %
95.3 X
80.8 Z
0.0 X
96.7 X
96.2 X
97.3 X
97.0 X
96.8 X
0.0 .X
0.0 X
95.8 X
96.4 X
97.2 X
96.9 X
97.3 X
76.2 X
0.0 X
0.0 X
90.9 X
97.1 X
96.8 X
78.2 X
0.0 X
25.0 X
94.0 X
94.9 X
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
25.
2.
2.
3.
3.
0.0 X
98.7 X
99.7 X
99.6 X
99.4 X
99.5 X
88.1 X
0.0 X
99.6 X
99.6 X
99.6 X
99.5 X
99.4 X
0.0 X
0.0 X
99.6 X
99.3 X
99.5 X
99.7 X
99.8 X
96.4 X
0.0 X
0.0 X
99.1 X
99.5 X
99.5 X
66.4 X
0.0 X
93.0 X
99.3 X
99.7 X
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
2.
187.
2.
2.
2.
2.
-15.0 X
19.3 X
-63.0 X
-43.6 X
-6.3 X
-9.2 X
2.5 X
-17.2 X
1.5 X
0.4 X
-52.3 X
-42.9 X
-10.4 X
-11.3 X
-6.4 X
8.7 X
-52.7 X
-35.9 X
-38.8 X
-9.6 X
-40.0 X
-29.2 X
-5.1 X
-25.6 X
-43.0 X
-5.7 X
-38.6 X
-30.3 X
-33.2 X
-a. 3 x
-45.8 X
997.
1061.
1237.
137Q.
1049.
1073.
1170.
1075.
1345.
1111.
1400.
1307.
1068.
1198.
935.
1131.
1356.
1500.
1310.
1153.
1125.
1075.
1061.
1284.
1353.
863.
1189.
1052.
1194.
1334.
1266.
-------
AUG 12 1973 TO SEPT 11 1973
AIRFLOWS IN CUBIC FEET
PLANT AIR CONSUMPTION
ASSUMED COST - S.000095/CF
AUTOMATIC PLANT CONTROL
AIRFLOWdfl
AIRFLOW#2
AIRFLOW*3
AIRFLOW**
TOTAL
COST
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
AUG
A'JG
AUG
AUG
AUG
AUG
AUG
SEPT
SEPT
SEPT
SF.PT
SEPT
SF°T
SEPT
SFPT
SEPT
SEPT
SEPT
12
13
14
15
16
17
18
19
20
21
2?
23
24
25
26
27
28
29
30
31
1
2
3
4
5
6
7
8
9
10
11
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
2974167.
3068177.
3309731.
3430249.
3507795.
3305319.
2922345.
2357687.
2914215.
3276073.
3098700.
3014951.
3356597.
3188579.
2444831.
2936301.
3339000.
33P3561.
3682953.
4001785.
3243780.
2371865.
2427375.
3102161.
3676597.
3785629.
3730001.
3351973.
2506517.
3281149.
3685737.
1193103.
1228392.
1370638.
1383687.
1508955.
1390726.
1180451.
852135.
1187702.
1346496.
1216564.
1195162.
1388529.
1320872.
1192552.
1642584.
1803914.
1832402.
2039544.
2186277.
1770578.
1075528.
1101258.
1557895.
2089570.
2032197.
2289099.
2386481.
1611614.
2605057.
3168753.
3054780.
3137245.
3414091.
3533688.
3418813.
3011929.
2436413.
2973303.
3365299.
3180275.
3092807.
3447277.
3296171.
2544513.
2985661.
3375713.
3425005.
3764160.
4057007.
3349081.
2484417.
2535453.
3245383.
3902103.
3966399.
3906450.
3480167.
2592545.
3414979.
3858093.
2757757.
2632067.
2454879.
2408570.
2387179.
2236073.
1970498.
1627886.
1955358.
2219603.
2123095.
2077042.
2265579.
2142173.
1684910.
1924833.
2084171.
2127655.
2299303.
2452203.
1941840.
1464660.
1551255.
2128367.
3145081.
3304593.
3365717.
2564599.
1826472.
2373963.
2628067.
9979807. - t
10065881. 1
10549339. 1
10756194. 1
11053374.
10350931.
9085223.
7274121.
9030578.
10207471.
9618634.
9379962.
10457982.
9947795.
7866806.
9489379.
10602798.
10778623.
11785960.
12697272.
10305279.
73°6470.
7615341.
10033806.
12813351.
13088818.
13291267.
11783220.
8537148.
11675148.
13340650.
948.08
956.26
I 1002.19
t 1021.84
t' 1050.07
f 983.34
863.10
691.04
85T.90
969.71
913.77
891.10
993.51
945.04
747.35
901.49
1007.27
1023.97
1119.67
1206.24
979.00
702.66
723.46
953.21
1217.27
1243.44
1262.67
1119.41
811.03
1109.14
1267.36
TOTAL
98685584.
50148608.
101898464.
70125248.
320857856.
S 30481.52
-------
AUG 12 1973 TO SEPT 11 1973
MONTHLY EFFICIENCY SUMMARY
AUTOMATIC PLANT CONTROL
PRIMARY
SECONDARY
CHLORINATOR
SS
BOD5
TOC
COO
AUG 12 1973 TO
UNITS - LBS
AVE
STD
AVE STD AVE STD AVE
47.7 X 12.3 X 75.3 X 10.1 X
25.8 8 17.5'X 88.3 X 4.8 X !
20.0 X 7.9 X 67.8 X 5.9 X
32.5 X 11.4 X 75.4 X 6.7 X
SEPT 11 1973 RESPIRATION SUMMARY
LOADING / 1000 CUBIC FEET OF AERATOR TANKAGE
SS BOD TOC
18.89 39.26 21.42
3.86 15.81 3.09
STD
78.1 X
84.6 X
66.7 X
74.6 X
AUTOMATIC
COD
58.92
12.44
8.0 X
5.8 %
7.3 X
5.2 X
PLANT CONTROL
-------
APPENDIX C.3
MLSS DATA
128
-------
N)
VO
SEPT 16 1973 TO OCT 16 1973
DESCRIPTION
TOTAL PLANT FLOW
LOS ALTPS FLOW
MT. VIEWFLOW
P H
D 0 il
0 0 #2
D 0 #3
D 0 IP4
AIRFLOW #1
AIRFLOW #2
AIRFLOW *3
AIRFLOW #4
TH *1 FLOW
TH #1 DENSITY
TH *2 FLOW
TH «2 DENSITY
TH *3 FLOW
TH #3 DENSITY
TH #4 FLOW
TH *4 DENSITY
RAS FLOW
WAS FLOW
MLSS i
MLSS #2
CHLORINE #1 RESIDUAL
CHLORINE FLOW #1
CHLORINE FLOW #2
CHLORINE FLOW *3
CHLORINE *2 RESIDUAL
SULFUR DIOXIDE FLOW
SPARE
SPARE
PROCESS DATA SUMMARY
AVE MIN
MAX
25.95
SENSOR NOT
SENSOR NOT
7.25
1.01
1.02
0.53
1.76
2626.91
1585.56
2730.44
1927.09
17.33
4. 83
11.89
3.43
12.68
4.86
OPERABLE
OPERABLE
6.16
0.10
0.10
0.10
0.47
531.41
24.42
306.81
619.41
0.0
0.0
0.0
0.0
0.0
NO VALID DATA
0.40
5.89
11.02
0.46
1557.21
1553.05
0.0
449.67
0.0
0.0
0.0
0.0
0.0
0.0
3.85
0.70
0.00
100. 00.
985.69
0.0
0.0
0.0
0.0
0.0
0.0
0.0
48.62
8.54
3.15
5.11
2.70
5.00
3914.88
3046.88
4087.38
3132.63
60.61
10.17
60.77
6.52
61.07
48.48
5.92
25.06
1.59
2052.00
3026.25
0.0
2058.00
0.0
0.0
0.0
0.0
0.0
AUTOMATIC PLANT CONTROL
STD UNITS
4.69 MGD
0.20
0.38
0.39
0.31
0.83
650.22
^32.82
687.80
514.27
15.42
2.74
12.95
1.76
14.47
3.45
0.14
?.60
0.24
196.27
184.73
0.0
490.95
0.0
0.0
0.0
0.0
0.0
MG/LIT5P
MG/LITEF
CFM
CFM
CFM
CFM
GPM
PE*CENT
GPM
PERCENT
GPM
GPM
PEPCFNT
MGO
MGD
MG/LITEP
MG/LITER
KG/LITE"
LB/DAY
LB/DAY
LB/DAY
MG/LITFP
LB/OAY
NO VALID DATA
-------
SEPT 16 1973 TO OCT 16 1973
LOADING DATA SUMMARY
AUTOMATIC PLANT CONTROL
SSfLBSI
XREMOVEDIEFFLUENT
BOD(LBS)
XREMOVEDIEFFLUENT
TOCCLBSI
XREMOVFDIEFFLUENT
CODUBS)
XREMOVEDIEFFLUENT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
OCT
OCT
DCT
OCT
OCT
DCT
HCT
OCT
OCT
OCT
DCT
OCT
C:T
DCT
OCT
OCT
16
17
IB
19
20
21
22
23
24
25
26
27
28
29
30
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
19.73
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
84.5 X
79.2 *
76.2 X
73.7 X
65.8 X
69.5 X
80.9 X
79.0 X
77.4 X
82.7 X
78.4 X
62.6 X
71.3 X
74.6 X
72.6 X
74.8 X
73.8 X
70.4 X
76.6 X
64.7 X
67.7 X
77.6 X
78.2 X
84.4 X
67.2 X
72.4 X
80.5 X
82.5 X
89.5 X
75.0 X
74.3 X
3952.
6499.
6329.
6202.
12105.
7817.
5860.
5783.
5870.
5103.
5493.
7415.
7661.
6627.
4704.
5918.
7341.
8947.
7435.
11881.
10980.
7313.
8483.
6525.
9309.
6537.
4980.
3841.
2291.
8331.
8385.
82.2 X
86.8 X
90.9 X
86.0 X
88.4 X
88.2 X
86.0 X
92.9 X
81.1 X
86.6 X
88.7 X
88.8 X
87.5 X
76.3 X
80.7 X
77.3 X
79.7 X
80.4 X
88.5 X
88.8 X
88.2 X
72.7 X
80.7 X
83.5 X
91.9 X
41.8 X
84.3 X
93.7 X
94.5 X
90.2 X
89.3 X
4311.
3777.
2572.
4201.
3697.
5471.
4102.
2034.
6773.
5724.
5010.
3795.
4990.
5592.
6381.
6965.
9221.
6711.
5272.
5111.
5038.
8908.
7634.
7830.
2997.
8655.
2445.
1536.
926.
3030.
3311.
60.6 X
55.9 X
57.0 X
55.1 X
53.3 X
64.0 X
56.4 X
67.8 X
67.7 X
46.1 X
59. 3 X
51.2 X
62.0 X
56.7 X
65.0 X
69.1 X
53.2 X
69.0 X
69.5 X
54.8 X
62.4 X
54.8 X
53.0 X
60.4 X
62.7 X
68.5 X
71.0 X
82.3 X
82.4 X
69.8 X
71.6 X
6646.
9139.
9392.
880?.
10784.
8685.
6641.
5783.
7224.
9096.
8569.
8941.
6566.
8077.
5727.
6601.
8488.
8053.
6534.
10536.
8827.
9307.
11075.
8389.
9309.
6537.
4527.
2987.
2189.
6688.
6544.
72.8 X
73.7 X
73.3 X
81.4 X
78.7 X
74.8 X
75.5 X
69.2 X
69.9 X
74.5 X
100.0 X
100.0 X
100.0 X
100.0 X
100.0 X
100.0 X
80.8 X
68.3 X
75.0 X
70.6 X
69.8 X
63.4 %
72.4 X
72.3 X
70.0 X
68.8 X
52.4 X
82.1 X
84.9 X
75.5 X
74.3 X
15627.
16247.
15925.
11804.
18927.
19324.
15039.
14757.
17384.
18635.
0.
0.
0.
0.
0.
0.
17663.
20803.
18249.
20399.
19162.
15733.
20972.
16778.
17028.
13524.
19919.
10028.
6414.
18496.
17003.
-------
SEPT 16 1973 TO OCT 16 1973
LOADING DATA SUMMARY
AUTOMATIC PLANT CQNTRDL
NH3CLBS)
XREMOVEDIEFFLUENT
N02(LBSI
XREMOVEDlEFFLUENT
N031LBS)
XREMOVEDlEFFLUENT
PHOS
-------
SEPT 16 1973 TO OCT 16 1973
AIRFLOWS IN CUBIC FEET
PLANT AIR CONSUMPTION
ASSUMED COST - S.000095/CF
AUTOMATIC PLANT CONTROL
AIRFLOWfl
AIRFLOW02
AIRFLOW#3
AIRFLOW**
TOTAL
COST
U>
KJ
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
SEPT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
OCT
16
ir
18
19
20
21
22
23
24
25
26
27
28
29
30
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
2596727.
3427263.
4037935.
3734079.
3947485.
3956011.
3870377.
3194263.
3504699.
3814107.
4060805.
4040201 .
4356777.
3660155.
2718000.
3396561.
3711653.
4103336.
4061129.
4307189.
4235455.
3429617.
3957807.
3529247.
4043413.
4272625.
4554009.
4089083.
3218119.
4052925.
3388037.
1756222.
2673115.
3376237.
3011905.
3356911.
3333411.
3376775.
2409421.
2162037.
2763693.
2775961.
2413823.
1937826.
2030440.
1671137.
2212061.
2771499.
2552371.
3153659.
2468325.
1161802.
1037350.
1577946.
1823784.
1926114.
1716851.
1730492.
2087203.
2238527.
1480402.
1795499.
2758455.
3587453.
4224330.
3890459.
4132541.
4109785.
4059677.
3326729.
3624815.
3943673.
4226139.
4222837.
4533905.
3840997.
2878763.
3555635.
3894555.
4282454.
4233197.
4495343.
4462935.
3342077.
3731053.
3530621.
4151723.
4515095.
4788159.
4332989.
3359659.
4254750.
3600397.
1978692.
2534839.
2894407.
2703819.
3023535.
3114941.
2685365.
2291293.
2836773.
3164021.
3281809.
3220111.
3207633.
2612757.
2042552.
2445871.
2640299.
2829927.
2687317.
3352201.
3575361.
2772691.
3022055.
2536539.
2765873.
2976783.
3002979.
2683141.
2213243.
2751747.
2177845.
9090096.
122226^0.
14532909.
13340262.
14460472.
14514148.
13992194.
11221706.
12128324.
13685494.
14344714.
13896972.
14O36141.
12144349.
9310452.
11610128.
13018006.
13768088.
14135302.
14623058.
13435553.
10581734.
12288861.
11420191.
12887123.
13481354.
14075639.
13192416.
11029548.
12539824.
10961778.
863.56
1161.15
13B0.63
1267.32
1373.74
1378.84
1329.26
1066.06
1152.19
1300.12
1362.75
1320.21
1333.43
1153.71
884.49
1102.96
1236.71
1307.97
1342.85
1389.19
1276.38
1005.26
1167.44
1084.92
1224.28
12P0.73
1337.19
1253.28
1047.81
1191.28
1041.37
TOTAL
117268880.
70782592.
121890928.
86026240.
395967744.
S 37617.04
-------
SEPT 16 1973 TO OCT 16 1973
MONTHLY EFFICIENCY SUMMARY
AUTOMATIC PLANT CONTROL
PRIMARY
BODS
TOC
COD
AVE
47.7 X
25.3 X
22.4 X
I 35.6 X
STO
11.0 X
22.4-*
10.7 X
16.1 X
SECONDARY
AVE STO AVE STO
67.7 X 10.6 X 75.4 X
88.0 X 4.3 X 84.4 X
61.6 X 8.9 X 62.4 X
73.2 X I 5.4 X 72.9 X
CHLORINATOR
6.3 X
9.5 X
8.6 X
6.9 X
SEPT 16 1973 TO OCT 16 1973
RESPIRATION SUMMARY
AUTOMATIC PLANT CONTROL
UNITS - LBS LOADING / 1000 CUBIC FEET OF AERATOR TANKAGE
ss
BOD
TOC
COO
AVE
STD
20.14
3.63
34.99
15.08
21.83
4.71
55.80
9.73
-------
APPENDIX C.4
MANUAL-2 DATA
134
-------
ui
OCT ?8 1"73 TO
DESCRIPTION
27 1973
PLANT FLOW
LOS ALTOS FLOW
MT. VIEV»CLOW
P H
0 0 #1
0 0 H2
0 0 #3
0 0 #4
HI
AIRFLOW *3
AIRFLOW #4
TH
TH
TH
TH
TH
#1
*?
*2
*3
#3
#4
#4
TH
TH
PAS FLOW
WAS FLOW
HLSS
MLSS *2
CHLOR INE
CHLORINE
CHL3f>INE
CHLORINE
CHLORIMF
OFNSITY
=L3W
DE'4SITY
FLOW
DENSITY
FLOW
DENSITY
HI PESIDUAL
FLOW #'
FLOW *2
FLOW «3
#2 RESIDUAL
SJLFUP DIOXIDE FLOW
TOC
PROCESS DATA SUMMARY
AVE MIN
I 29.2 0.01
SENSOR NOT OPERABLE
SENSOR NOT OPERABLE
7.31 5.90
0.88
1.03
0.94
1.23
2230.95
15?1. Q2
1984.43
1338.27
NO VALID
5.82
NO VAL ID
3.11
15.25
5.38
1.98
5.65
12.64
0.78
1868.88
1480. TT
MO VALID
530.92
NO VALID
MO VALID
NO VALID
NO VALID
MO VALID
121.35
DATA
DATA
DATA
DATA
DATA
DATA
DATA
DATA
0.10
0.10
0.10
0.10
244.74
28.52
0.19
102.71
5.10
0.0
0.0
0.0
0.0
0.0
4.77
J.OO
0.62
548.31
0.0
5.23
MAX
50.15
8.20
3.02
5.15
3.90
5.05
4402.75
3241.13
4313.75
2829.75
6.14
61.00
7.89
33.30
5.91
18.13
1.69
7294.50
2241.63
911.25
AUTOMATIC PLANT CONTROL
STD UNITS
1 6.37 MGD
0.35
0.38
0.55
0.53
0.6f
666.3"
563.50
732.96
525.16
0.27
1.01
23.43
1.04
7.24
0.94
1.50
0.16
837.66
2B9.72
135.23
MG/LITEP
MG/LITER
MG/LITER
CFM
CFM
CFM
CFM
PERCENT
PERCENT
GPM
PFRCENT
GPM
PERCENT
MGO
MGO
MG/LITER
MG/LITER
LB/DAY
253.69
44.30
MG/LITER
-------
OCT
1«73 TO MOV 27 19?3
LCADfNG OATA S
4UTQMATIC PLANT CONTROL
OCT
OCT
OCT
OCT
NOV
NJV
NQV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
Nny
NOV
NOV
NOV
NOV
NOV
NOV
NDV
NOV
N'JV
NOV
28
29
10
31
1
2
3
4
5
6
7
P
9
10
11
12
13
14
15
16
17
18
19
20
n
22
23
?4
25
26
27
1973
197?
197?
197?
T97?
1 57?
!97?
197?
197?
1973
197?
.'. S73
1073
1^73
197?
197?
1 Q7?
197?
1973
197?
1.973
1973
10-7?
197?
1973
1973
197?
1 °7?
1973
1973
1973
SSJLBSt
Rr,M°VEDlFFf
1 00.0 %
85.Q ?,
P9.1 t
67.9 ?
77.5 I
30.7 %
61.1 %
65.4 %
56.7 %
66.9 %
82.4 %
90.1 3!
83.5 *
77.6 %
86.2 «
89.4 *
74.1. ?
89.7 *
88.5 *
93.0 S
68.7 X
90.0 *
84.4 3!
9O.O %
34.3 %
ao.i ?
88.5 1
91. -3 ?
90.1 *
87.3 *
86.0 *
:LIJF.WT
0.
46?4.
6234.
"207.
6328.
16254.
7838.
9725.
11024.
10695.
6351.
4157.
5649.
5647.
4831.
5399.
7P25.
4714.
6002.
4804.
5500.
?746.
7571.
3216.
4251.
6321.
4863.
?f59.
3855.
5286.
5550.
BODILBS
*PEVnvcr)|rF
100.0 *
64. 4 %
55.8 *
61.5 t
40.0 ?
95.3 %
95.3 *
95.9 35
P0.6 X
80.0 %
82.9 *
7«.4 *
79.7 *
70.2 %
85.3 %
flO.5 X
80.5 *
8Q.8 %
87.0 %
81.9 *
78.9 %
74,7 S
64.7 5?
8O.O %
82.9 35
91.6 35
8Q.l 35
90.1 1
91.2 X
93.4 I
95.5 35
J
FLUENT
0,
10569,
975?
10806,
11 108
1951,
2415,
1776,
«B19.
8058,
6401
8418,
11709
10305
4969
1247?
12050
6023
7150
10012
1.1628
i 1. 3 8 7
3145
11577
5579
2669
*3?4
3064
2665
2651
1517
TOC(LBS)
f OltFFLUENT
100.0 ?
85.2 *
70.3 %
71.3 X
63.8 X,
55.4 %
57.7 %
63.9 %
69.^ %
63.P %
66.3 %
65.9 *
69.5 %
62.7 ?
76.? %
74.3 *
58.1 *
74.3 %
71.7 ?
71.4 %
53.2 S
73.2 *
82.4 %
75.5 *
81.6 35
P0.6 S
83.7 *
84. ? 35
80.1 *
75.8 *
81.1 *
0.
3963.
6680.
7067.
7968.
6734.
6991.
6342.
5390.
6467.
7113.
7275.
7447.
6588.
5521.
^829.
9390.
7333.
8351.
6068.
5762.
3995.
4960.
6164.
4251.
4682.
3705.
3887.
4510.
6437.
5017.
COD(LBS)
PF"ir>vFD| EFFLUENT
100.0
ei.o
77.9
7f.3
76.9
6ft. 5
6?. *
70.5
7?.l
74.7
67.6
68.1
74.1
73.0
7fi,2
79.9
79.7
80.6
82.9
80.6
60.1
7fi.2
83.5
81.1
73.0
80.1
87.6
85. t
83.4
PI. 9
80.5
%
%
35
*
*
*
%
%
*
*
*
*
%
%
%
%
%
*
?
%
%
%
%
%
%
%
%
%
%
%
%
0.
14092.
14606.
1C047.
14999.
1950S.
2160P.
17125.
1812°.
'9649.
29722.
27282.
?105fr.
18586.
If ??4.
18898.
37475.
16237.
14QP2.
13653.
14928.
1*?_33.
14097.
15811.
16472.
12642.
10651.
10519.
1201?.
15112.
14418.
-------
OCT 28 1313 TO NHV 27 19?3
LOADING DATA SUMMARY
AUTOMATIC PI ANT COMTRDL
NH31LBSJ
SPFMOVFDIEFFLUENT
N02(LBS)
*REMQVEO|EFFLUENT
N03CLBS)
SREMOVEDIEFFLUENT
PHOS(LBS)
^REMOVED I EFFLUENT
LO
OCT
OCT
OCT
OCT
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NJV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
N3V
NOV
N1V
N3V
NOV
N3V
NOV
NOV
NOV
28
29
30
U
1
2
2
4
5
6
7
8
9
10
11
12
13
14
15
16
17
19
19
20
21
2?
23
24
25
26
27
1973
1973
1973
] 973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1 973
1973
1«73
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
13T*
1973
100.0 X
10.9 X
11.1 %
3.13 %
0.0 X
-1.4 X
1.4 X
-15.7 X
19.1 *
7.7 X
16. f X
2.3 X
-12.5 X
-20.0 X
-2?. 8 X
19.4 %
12.2 X
-1.4 X
1.3 X
-1.2 X
2.6 X
-6.0 X
31.9 X
-4.2 %
1.4 X
-9.0 X
-10.6 X
-9.2 X
-14.0 X
0.7 X
12.0 X
0.
6275.
8016.
8321.
8905.
8592.
7626.
6237.
6737.
7462.
10161.
11173.
11555.
9881.
8052.
7ft29.
"477.
9690.
9917.
1.0366.
9690.
6617.
6135.
9915.
9166.
8545.
8452.
8118.
7373.
8110.
8118.
100.0 X
97.0 X
95.5 X
9ft. 2 X
9K.3 X
96.9 X
80.0 X
0.0 X
80.0 X
93.3 X
89.6 X
87.8 X
88.9 X
84.6 X
66.7 X
89.5 X
9«?.l X
97.8 X
97.1 X
98.6 X
9* .4 X
94.1 X
94.7 X
86.4 X
95.5 X
95.0 X
75.0 X
50.0 X
93.5 X
96.8 X
<32.8 X
0.
2.
2.
2.
2.
2.
2.
2.
2.
2.
13.
13.
10.
5.
2.
5.
3.
3.
3.
3.
3.
2.
5.
8.
3.
2.
2.
2.
2.
3.
6.
100.0 X
99.6 X
98.7 X
9Q.5 X
95. 9 X
99.7 X
98.1 X
0.0 X
99.6 X
93.! X
64.0 X
80.7 X
26.1 X
33.3 X
58.3 X
99.1 X
76.1 X
99.2 X
99.6 %
99.4 X
98.6 X
94.1 X
99.6 X
66.9 X
94.4 X
98.7 X
0.0 X
95.0 X
91.8 X
91.7 X
92.8 X
0.
2.
2.
2.
23.
2.
2.
2.
2.
90.
114.
187.
167.
66.
46.
3.
55.
3.
3.
3.
3.
25.
3.
126.
53.
2.
?.
2.
6.
31.
49.
100.0 X
79.7 X
-1«.5 X
-25.5 X
-12.1 X
-19.6 X
-28.3 X
-9.5 X
-16.2 X
-30.0 2
3.4 X
-7.7 X
-18.0 X
-25.3 X
-22.7 X
-29.9 X
-20.1 X
-25.1 X
-13.7 X
-84.4 X
-10.7 X
-36.3 X
-9.5 X
-42.7 X
1 .1 X
-23.0 X
11.6 X
-12.3 X
-25.6 X
-43.6 X
-31.7 X
0.
271.
1269.
1258.
1261.
1358.
1218.
1216.
1298.
1293.
1229.
1195.
1381.
1468.
1392.
1479.
1322.
1398.
1451.
1492.
1270.
1246.
1201.
1568.
1196.
1100.
9^2.
1189.
1098.
133.9.
1045.
-------
0-T 28 1973
TO NOV 27 1973
PLANT MIX LIO
FLOW SVI
IMGO)
u>
oo
OCT
OCT
OCT
OCT
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NW
NOV
NOV
MOV
NOV
NOV
N3V
N.1V
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
28
29
30
31
1
2
3
4
5
e
7
9
9
10
11
12
13
\i
15
16
17
18
19
20
21
22
23
24
?5
26
?7
1973
1973
1973
1973
1973
1973
1973
1973
1973
1973
19^3
1973
1973
1=73
1973
1973
1973
1973
1973
1973
3 973
1973
1C73
1973
197?
3 973
1973
197?
1973
'973
197?.
26.40
26.70
27.3*
28.10
27.84
25.40
25.35
?9.37
29.82
30.46
31 .15
30.79
26.21
27.58
32.37
?1.27
?" .40
31. 29
30.32
31.40
29.94
31.30
3?. 13
31 .35
J8.07
27.76
27.42
?6.°2
3J.67
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
FLOW DATA
MIX LIO
SS SLO
(MGLI
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
o.o
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
SUMMARY
RAS
(MGL)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
AUTOMATIC PLANT CONTROL
WAS
( MGL )
0.0
0.0
0.0
0.0
0.0
0.3
0.0
o.q
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0 0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
-------
28 1973 TO NOV 27 1973
AIRFLOWS IN CUBIC
PLANT AIR
ASSUMED COST - '$.000095/CF
AUTOMATIC PLANT CONTROL
AI
AIRFLOW#2
AIPFLOw*3
AIPFLOW»4
TOTAL
COST
OCT
OCT
GCT
OCT
NOV
NOV
NOV
NOV
N3V
NHV
NOV
N3V
NOV
N3V
N'lV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
NOV
13
?9
30
n
i
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
1.8
19
20
21
->?
23
24
25
26
27
1^73
197-3
1973
1973
1973
1973
1973
1973
1 S73
1973
1973
1973
1973
1973
1973
Itf*
1973
1973
1973
1973
197?
1973
1973
1973
1973
1973
1973
1973
1973
1973
197?
3666377.
3H00539.
32007^1.
TOTAL
3051505.
3330531.
2355839.
2806511 .
365
-------
OCT
?97'* TO
27 1
MONTHLY FFFICIEVCY SUMMARY
AUTOMATIC PLANT CONT"CL
ss
BIDS
TIC
C ID
AVE
9.1 X
20.4 X
27.6 X
STD
19.0 X
11.5 X
17.8 X
14.4 X
AVF
STD
77.4 X
85.7 X
74.3 %
76.4 ?
AVF
12.9 X
9.8 X
8.2 X
8.5 X
CHLORINATE
STO
79.8 X
31.5 X
71 .6 3!
76.9 %
13.5 ?
11.7 X
9.1 X
6.6 ?
OCT ?B 1973 TO NOV ?7 1973
RESPIPATION SUMMARY
AUTOMATIC PLANT
JNITS - LRS LDAOWG / 1000 CUBIC FEET OF AERATOR TANKAGF
SS
son
Tnc
C1D
STD
18.48
5.32
38.4
12.48
17.45
2.95
52.26
8.37
-------
APPENDIX C.5
AIR/RAS DATA
141
-------
(S3
JAM 13 1974 TO F£t} 12 1974
DESCRIPTION
TOTAL PLANT FLOW
LOS ALTOS FLOW
MT. VIPHPLrw
P H
D 0 #1
n 0 ?2
DO*?
D 0 *4
AIRFLOW #1
AIRFLOW «2
AIRFLOW #3
AIRFLOW #4
TH «1 FLOW
TH *1 DENSITY
TH #? FLOW
TH #? DENSITY
TH m FLOW
TM #3 OeNSlTY
TH #4 FLOW
TH #4 DENSITY
RAS FLOW
WAS FLOW
MLS?
MLSS #2
CHLORINF #1 RESIDUAL
CHLORINE FLOW #1
CHLORINE FLOW #2
CHLORINE FLOW #3
CHLORINF #2 RFSIDUAL
SULFUR DIOXIDE FLOW
RPSPIRCMFTFR
TOC
PROCESS OATA
AVF MIN
| 26.8 0.03
SFNSOR N"T opc?A«?Lc
SFNSOR NPT OPERAPLF
6.76
O.77
0.77
1.07
0.50
1936. 42
1003.44
1543.70
1555.84
14.30
4.83
28.27
3.89
0.76
4.80
38.7?
4.07
11.52
0.41
1576.31
1762.99
NO VALID OATA
264.52
NO VALID DATA
NO VALID DATA
NO VALID OATA
NO VALID f>ATA
6.01
NO VALID DATA
4.55
0.10
0.10
0.10
O.in
94.32
1.12
2.98
12.68
0.0
0.39
0.0
0.0
0.0
0.03
0.00
0.41
0.36
0.00
33.92
296.55
9.44
0.0
AUTOMATIC PLANT CONTROL
MAX STD UNITS
52.68 10.0
8.05
2.83
2.89
3.21
3.65
3605.50
2477.75
2994.63
3651.13
60.52
5.56
60.56
6.03
56.06
5.37
60.82
6.47
21,17
1.30
2554.63
2721.13
698.50
95.43
0.75
0.35
0.35
0.43
0.56
678.23
685.78
530.72
631.16
18.88
0.43
20.49
1.03
5.09
0.18
11.95
0.97
3.53
0.27
444.23
460.20
107.46
6.49
WG/LITFR
MG/LITFR
MG/LITEP
MG/LTTER
CFM
CFM
CFM
GPM
GPM
PFRC*NT
GPM
GPM
MGD
MGD
MG/LITER
MG/LITFR
LB/OAY
MG/LITER
-------
JAN 13 1974 TO FES I? 1974
LOADING DATA SUMMARY
AUTOMATIC PLANT CONTROL
SSCLBS)
AFFLUENT
BO.DILBS)
js
to
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAM
JAN
JAN
JAN
F£R
FFR
FEB
F"e
FEP
FC<*
FCB
F<=*
FFB
FFF,
FE"
F*n
13.
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1
2
3
4
c
6
7
P
Q
10
11
12
1974
1974
1974
19 7 A
1974
1974
1974
1974
1974
1974
1974
1974
i<>74
1974
1074
1974
1074
1974
1974
1974
1974
1974
1974
1974
1974
1974
IP 74
1974
1974
1974
1974
TOCCLBS)
^REMOVED|AFFLUENT
COD(LBS)
SRFMOVEDlEFFLUENT
67.0
8i> e
87.5
63.3
70.2
76.3
70.4
68.0
81.0
60.5
55.3
75.1
73.9
100.0
88.0
87.5
96.1
87.6
84.5
68.1
79.?
86.7
91.0
94.4
81.2
f,b. 3
76.6
72.9
«<2.c,
P3.7
SO. 9
*
3
%
%
%
r
%
%
%
*
*
*
t
f
?
?
7
*
?
«v
">
T
t
-------
JAN 13 3974 TO
12 197*
LOADING DATA SUMMARY
AUTOMATIC PLANT CQNTRHL
EFFLUENT
7RFMOV?DIFFFLUFNT
PHDS(LSS)
IFFFLUFNT
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
FE«
FFB
FE«
Fc74
7 1974
8 1974
9 1974
10 197*,
11 1074
12 1974
-7.8 %
9.7 %
24. ? t
-9.5 S
0.5 ?
18.6 ?
-23.4 «
-8.6 ?
22.0 T .
-8.3 5
20.8 T
-4.4 9!
14.9 3!
loo.o r
100.0
100.0 7.
100.0 r
8.7 %
-B.I ?
2.1 y
-6.4 T
-69.? ,r
7.? *r
31.3 T
2.3 *
24.1 T
o.o i
1.1 r
-1.7 ?
8.P T
5.6 *
7869.
ee&6.
10054.
13307.
10162.
8879.
8882.
6450.
7625.
12352.
0683.
5460.
B923.
0.
0.
0.
0.
9202.
10953.
8112.
6324.
3546.
3991.
3278.
9324.
8728.
12423.
88C7.
6440.
7954.
5205.
0.0 *
88.9 T
92.0 t
68.7 r
94.1 T
75.0 t
75.0 %
o.o r
87.5 f
9?.? t,
80.0 T
100.0 T
100.0 *
100.0 *
100.0 T
100.0 t
100.0 »
60.0 f,
100.0 *
69.2 r
40.0 *
o.o ?
5^.0 ?
44.4 7
50.0 Jt
64.3 T
58.3 T
98.0 r
97." »
76.4 1?
83.1 *
2.
3.
5.
14.
3.
3.
2.
2.
2.
2.
7.
0.
0.
0.
0.
0.
o.
9.
0.
9.
6.
2.
11.
22.
11.
11.
11.
0.
^.
6.
3.
-5899.9 ?
99.2 %
99.7 t
po.o r
99.7, *
99.6 *
99.5 f
98.0 T
09.6 Z
99.8 *
99.7 *
100.0 t
100.0 *
10C.O %
100.0 S
100.0
-------
JAN 13 1974 TO
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAf!
JAN
JAN
JAN
JAN
JAN
JAN
JAN
JAN
FEB
FEE
FEP
F^B
FEB
FER
FES
FEP
FER
FPS
FFB
FEC
13
14
15
16
17
IP
1
-------
13 1974 TT FfP 17
AIRFLOWS TN CU^IC PTc
PLANT A I?
ASSUMED COST - *.OOOO°5/CP
PLANT
AT1! FLOW* 2
A IPFLOW*4
TOTAL
COST
JAN
JAM
JAN
JAN
JAN
JAW
JAM
JAN
JAN'
JAN
JAN
JAN
JAN
JAN
JAN*
JAN
JAN
JAN
JAN
FFB
FEE
FPP
FPR
F?B
FSB
F«=p
FFK
FEB
FEB
Fcfi
FPp
12
14
1?
16
17
1«
1<>
?P
,21
2?
23
24
7f,
26
27
?S
29
30
31
1
>
3
4
c
6
7
8
e
10
11
12
!«?74
1974
1<»74
1974
1974
1 071.
2549C4I}.
2255445.
2371015.
17004?!.
2300997.
TPTAL
288f863.
2363811.
1*63071.
254P29?.
2826419.
86442016.
117170.
124,
2544921.
2409465.
245R225.
2116890.
1762377.
17645?5.
1R76157.
1400255.
1302131.
1918808.
1742963.
2090010.
2104727.
1947940.
16221C3.
1856966.
177R969.
1237058.
2529175.
3124823.
229P327.
1791851.
2672701.
2815313.
680223?.
7826534.
90807P9.
9281975.
«42660?.
9920165.
10097793.
8943268.
9173703.
9639B99.
9851446.
970754P.
9648868.
9301270.
6346947.
7684250.
B463586.
7654243.
8142774.
8519685.
S328015.
6357853.
7928421.
7687153.
7591573.
9397659.
93755S6.
8435470.
7260071.
10459734,
10768510.
*
t
t
«
f
1
$
«
t
*
t
S
$
t
t
.1
*
$
$
s
$
t
*
«
f
$
* .
$
*
*
* '
646.21
743.52
B62.67
861.79
8Q5.53
942.42
959.29
849.61
871. SO
915.79
935.89
922.22
916.64
883.62
602.96
730.00
804.04
727.15
773.56
809.37
791.16
604.00
753.20
730.28
721.20
892.78
938. Ifi
801.37
669.71
993,67
1023.. 01
69453040.
269603328.
25612.30
-------
JAM 13 1974
f-B 12 1974
MONTHLY FFFICIFNCY SUMMARY
AUTOMATIC PLANT CONTROL
SS
B005
rrc
ceo
PRIMARY
»V«= STD
54.5 % 10.1 T
20.0 % 14.3-%
?4.S % 12.3 *
35.4 5 9.2 f
SECONDARY
STO
77.0 *
86.7 *
7?.5 t
7«5.8 S
CHLORINATOP.
AVF
10.2 £
4 . CJ : % '
6.3'T
7.4 t
STD
79.6 T
87.6 « '
71.3 T
75.2 T
9.4
, 6.0
7.3
7.9
JAN 13 1974 TO PF5 1? 197*
RFSPIBATIHN SUMMARY
AUTOMATIC PLANT CONTROL
UNITS - I?S LOADING / 100O CUBIC P?FT CF AFRATHP TANKAGF
SS
TOC
COD
STD
31.60
13.00
17.97
41.IB
0.68
-------
APPENDIX C.6
RESP/RAS DATA
148
-------
FE& 13 IS 74 TO MAR 12 1974
DESCRIPTION
TOTAL PLANT FLOW
LOS AllCS FLOW
rfT. VI Eh FLOW
P H
0 0 II
0 0 *2
0 0 13
0 0 *«
AIRFLCta #1
4IRFLO 12
AIRFLCW t3
AIRFLCh I*
TH II FLOW
TH II CENSITY
TH 12 FLOh
TH #2 CENSITY
TH 13 FLOW
TH *3 DENSITY
TH 14 FLOW
TH I* CEKSITY
RAS FLCh
MAS FLCW
MLSS
MLSS 12
CHLORINE «1 RESIDUAL
CHLORINE FLOW II
CHLORINE FLOW 12
CHLORINE FLOW 13
CHLORINE §2 RESIDUAL
SULFUR CICXIDE FLOW
*ESPI«C>ETER
TOC
PROCESS DATA SUMMARY
AVE MIN MAX
24.72 0.12 51.28
SENSOR NOT OPERABLE
SENSOR NOT OPERABLE
6.94 6.91 6.96
I .816 0.10 3.61
! .828 0.10 3.64
.928 0.14 2.77
: _.861 0.16 3.72
179S.62 42.50 3435.88
1470.58 155.27 2947.13
1715.43 1.12 3805.88
1812.60 16.03 3577.13
NO VALID CATA
5.C3 C.33 5.48
35.68 0.0 60.66
4.29 0.25 7.25
4.50 0.0 60.02
5.07 0.39 9.47
35.37 0.0 60.49
3.95 0.01 7.6S
12.77 6.31 20,34
C.S7 0.00 2.05
1400.45 210.45 2022.88
1545.03 1026.69 1953.06
NO VALID DATA
1478.68 8.04 4847.75
NO VALIC CATA
NO VALID DATA
NO VALID CATA
NC VALID CATA
11.68 C.10 25.2S
59.69 0.0 253.03
AUTOMATIC PLANT CCNTROL
STD UNITS
8.79 fGD
0.05
.434
.456
.389
.644
624.74
479.66
680.79
734.18
0.09
10.81
C.74
9.41
0.96
14.38
1.27
2.9«5
0.57
292.81
220.82
892.44
MG/l ITEP
MG/LITER
MG/LITEP,
MG/LITEf
CFM
CFf
CFM
CFM
PERCENT
GPM
PERCENT
GPf
PERCENT
GPM
PE(?C=NT
MGO
MGD
f*G/L ITEP
KG/LITFP.
LE/^^v
6.10
36.41
PG/LITEP
fG/LITFP
-------
FEB 13 ISM TO MAR 12 1974
LCADING DATA SUMMARY
AUTOMATIC PLANr CONTROL
SS(LBS)
XREMOVEDI EFFLUENT
BOC(LBS) TOCtLBS) COD(LBS)
XREMOVEOIEFFLUENT XREMCVEDI EFFLUENT XREMQVEDIEFFLUENT
FES
FEB
FE8
FEB
FEB
FEB
fEfl
FEB
FEB
FEB
FEB
FEB
FEU
FEB
FEB
FEB
MAR
f AR
CAR
KAA
PAR
MR
PAR
FAR
MAR
MAR
MAR
MAR
U 1974
14 1974
15 1S74
16 1974
17 1S74
IS 1S74
19 1974
20 1974
21 1974
22 1974
23 1S74
24 1974
25 1974
26 1914
27 1974
28 1974
1 1974
2 1974
3 1974
4 1974
5 1974
6 1974
7 197*
8 1974
9 IS 74
10 1974
11 1974
12 1974
75.7
74.0
76.9
92.8
78.0
79.0
85.4
83.2
83.2
73.5
78.5
83.3
89.5
85.1
87.3
94.1
100.0
90.1
89.2
93.1
74.6
83.3
87.9
91.0
100.0
83.5
81.8
83.6
8403.
6872.
5078.
2544.
5032.
6204.
4614.
3651.
71C6.
6594.
6CC8.
5 IOC.
4529.
4097.
4C40.
3120.
0.
5832.
4272.
3015.
7086.
3735.
3C46.
2695.
0.
6426.
8346.
6979.
89.4 %
81.6 X
87.9 %
91.4 X
94.5 %
89.6 %
91.5 X
92.4 %
88.9 *
87.4 X
87.9 *
90.0 %
76.0 X
89.4 *
95.9 X
96.3 x
95.3 *
93.8 %
96.4 X
92.6 X
91.6 ?
94.8 X
94.2 X
95.4 X
100.0 X
92. 1 X
93.9 *
95.6 X
3443.
7371.
39CO.
22SC.
14tl.
2846.
2232.
2069.
3332.
2836.
2929.
2566.
2836.
21C7.
1385.
1622.
1961.
1884.
1349.
2366.
279C.
2109.
23C9.
1617.
0.
2515.
2147.
1554.
65.7 %
61.0 t
58.4 f
72.7 X
£3.1 *
74.7 *
81.1 %
61.3 *
74.7 X
66.7 *
81.6 %
82.6 %
1CC.C t
63.8 1
£4.8 1
83.6 1
82.4 1
61.9 %
69.8 %
80.0 *
70.0 %
77.3 *
79.6 %
6.6 1
100.0 *
78.5 X
76.6 1
79.0 *
6969.
8121.
7516.
4907.
3896.
4197.
5252.
SS83.
5553.
4C82.
2629.
2468.
0.
2341.
3655.
52CO.
5836.
9422.
5645.
4407.
4650.
4394.
3848.
2854.
0.
4173.
5482.
5523.
76.6 *
96.8 %
72.1 %
86.4 %
75.4 %
79.6 X
76.7 %
78.0 X
79.3 1!
73.5 %
84.5 %
78.4 X
84.4 X
69.9 ?
81.3 X
83.0 X
79.4 X
84.4 X
81.0 X
80.6 X
74.2 *
69.9 X
75.9 X
83.5 <
100.0 %
75.5 S
77.0 X
76.9 <
14962.
2291.
16454.
12358.
10227.
11313.
15098.
13186.
15105.
13965.
1C 890.
10529.
14375.
15997.
14621.
14768.
16341.
15703.
12815.
14150.
13602.
14S40.
14178.
9829.
0.
15843.
18548.
19674.
-------
1CB.....11. 1S.7.4 TO MAR 12 1974
LOADING DATA SUMMARY
AUTOMATIC PLANT CONTROL
NH3CLBS)
tREMOVEDlEFFLUENT
NC2(LBS) K03(LBS) PHOS(LBS)
XREMOVEDl EFFLUENT XREHCVECIEFFLUENT XREMOVEDl FFFLUENT
FEB
FEB
FEB
FEB
FE8
FEB
FEB
FEB
FEB
FEB
FEB
FEB
FEB
FEB
FEB
FES
CAR
PAR
PAR
MAR
PAR
PAR
PAR
MAR
PAR
PAR
MAR
PAR
13 19T4
14 1974
15 1974
16 1974
17 1974
18 1974
19 1974
20 1974
21 1974
22 1974
23 1S74
24 1974
25 1914
26 1974
27 1974
28 1974
1 1S14
2 1974
3 1*14
4 1974
5 IS74
6 1*74
7 1974
8 1*74
9 1974
1C 1*74
11 1974
12 1974
17.0
100.0
100*0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100. O
25.0
12.5
8.2
-2.3
8.0
13.6
13.5
5.9
10.5
15. C
-5.3
11.0
100.0
-6.3
12.7
4.0
9018.
0.
C.
0.
0.
0.
0.
0.
C.
0.
0.
0.
6271.
8194.
6445.
4680.
5369.
4262.
3597.
3711.
3765.
3735.
4051.
2822.
C.
3518.
3813.
4830.
9*. 4 %
100.0 X
1CC.O X
100.0 %
100.0 X
100.0 X
1OO.O X
100.0 X
100.0 X
100.0 X
100.0 X
100.0 X
56.3 X
75.0 X
-162.5 X
87.0 X
99.4 X
99.5 X
99.4 X
55.6 X
82.8 X
97.2 X
93.3 X
90.0 X
100.0 X
86.5 X
92.3 X
82.8 X
0.
0.
0.
C.
0.
0.
0.
0.
C.
0.
0.
C.
69.
12.
40.
6.
C.
C.
0.
19.
11.
2.
4.
5.
C.
2.
4.
9.
85.7 X
100.0 X
100.0 X
100.0 X
100.0 *
100.0 X
100. C X
100.0 X
10C.O X
100.0 *
100.0 X
100. C X
62.5 1
38.5 X
19.4 X
71.8 3
94.0 X
99.9 X
99.9 *
79.9 X
90.2 J
91.7 X
S3. 2 *
91.3 %
10C.O *
65.5 *
94.9 *
91.9 X
61.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
59.
94.
112.
129.
33.
0.
0.
158.
89.
73.
47.
49.
0.
32.
29.
62.
4.9 %
100.0 X
100.0 7,
100.0 2
100. 0 X
100.0 X
100.0 S!
100.0 %
100.0 %
100.0 %
100.0 X
100. 0 X
22.3 X
-75. 5 %
9.0 *
27.8 X
13.3 9!
6.8 X
19.2 X
7.5 X
-12.7 X
8.6 %
23.9 X
5.3 X
100 .0 %
-3.3 X
2.3 %
-14.5 X
799.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
857.
839.
875.
9C9.
819.
803.
719.
997.
me.
383.
747.
598.
0.
990.
use.
1179.
-------
ho
FEB
FEB
FEB
FEB
FEB
FfJ5
FEB
FEB
FEB
FEB
FEB
FEB
FES)
FEB
FEB
KAR
MR
MA.R
MAR
MAR
PAR
MAR
PAR
PAR
PAR
PAR
MAR
14 1974
15 1974
16 1974
17 1974
18 1974
^.19 1974
20 1974
21 1914
22 1974
23 1S74
24 1974
25 19 7<
26 1974
27 1974
28 1974
I 1S74
2 1974
3 1574
4 1974
5 1974
6 1974
7 1*14
a i9?4
? 1S74
10 1974
11 1974
12 1974
*- 12 1974
-ANT MIX LIfl
= LOM
IMGD)
24.58
24.97
24.36
21.79
19.46
21.88
26.24
24.32
26.63
29.76
22.51
19.73
23.61
23.39
23.07
24.94
27.99
26.90
26.96
27.81
26.55
26.34
24.29
19. Ol
22.02
26.57
29.65
30.80
SVI
0.0
0.0
o.c
c.o
0.0
c.o
0.0
0.0
c.c
0.0
0.0
0.0
0.0
o.c
c.c
0.0
0.0
c.c
0.0
o.c
0.0
0.0
c.c
0.0
c.c
75,17
79.83
78.58
FLOW DATA SUMMARY
MIX LIO
SS SLD
-------
FEB 13 1974 TO MAR 12 1974
AIRFLCtS IN CUBIC FEET
PLANT AIR CCNSUHPTICK
JSSUMEC COST - I.OOC095/CF
AUTOMATIC PLAUT CONTROL
AIRFLOW*!
AIRFLOWS
AIRFLOW#3
AIRFLOW#4
TOTAL
COST
FEB
FEB
FEB
FEB
FEB
FEB
FEB
FEB
FEB
FEB
FEB
FEB
FE8
FEB
FEB
FEB
MR
MAR
MR
MAR
MAR
MR.
CAR
MAR
MAR
MAR
MAR
MAR
13 1974
14 1914
15 1974
16 1514
17 1974
18 1974
19 1914
20 1914
21 1974
22 1S74
23 1974
24 1974
25 1974
26 1974
27 1974
28 1974
I 1974
2 1*14
3 1974
4 1374
5 IS74
6 1974
7 1914
8 1974
9 1974
10 1974
11 1914
U 1974
2907063.
2740665.
2851200.
2312823.
1527395.
1946375.
2461315.
3021793.
3136239.
3365932.
2817639.
2205433.
3296601.
3592417.
306C791.
2665353.
2585425.
2097063.
1627(10.
2259087.
2545693.
250CS93.
2753905.
2850413.
2268207.
1841431.
253794S.
2785347.
2276137.
2295131.
2404463.
1999801.
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-------
FEB 13 1974 TO MAR 12
MCNTHLY EFFICIENCY SUMMARY
AUTOMATIC PLANT CONTROL
PRIMARY SECONDARY
AVE STD AVE STD AVE
ss
9005
TOC
COO
52.6 OL
32.4 «
38.9 *
37.9 X
20. ll*
16.6 X
1 16.4^X
16. C X
, 82.7 X
' 89.0 X
77.7'X
78.4 X
5.8 X
4.5 X
7.6 *
4.0 X
CHLORINATOR
STD
83.8 X
91.9 X
75.3 X
79.1 X
6.2 X
4.2 X
; 8.5 X
5.8 %
FEB 13 IS74 TO HAH 12 1974
RESPIRATION SUMMARY
AUTOMATIC PI ANT CONTROL
UNITS - IBS LOADING / 10GO CUBIC FEET OF AERATOR TANKAGE
SS
BOO
AVE
STD
15.66
6.66
21.43
I
5.95
TOC
12.34
/.
3.36
COD
42.16
11.53
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-670/2-75-039
3. RECIPIENT'S ACCESSIOIvfNO.
TITLE AND SUBTITLE
ADVANCED AUTOMATIC CONTROL STRATEGIES FOR THE
ACTIVATED SLUDGE TREATMENT PROCESS
5. REPORT DATE
May 1975; Issuing Date
6. PERFORMING ORGANIZATION CODE
AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Joseph F. Petersack and Richard G. Smith
PERFORMING ORGANIZATION NAME AND ADDRESS
Systems Control, Inc.
1801 Page Mill Road
Palo Alto, California 94304
10. PROGRAM ELEMENT NO.
1BB043; ROAP 21ASC; Task 007
TTTi
r/GRANT NO.
R800356
2. SPONSORING AGENCY NAME AND ADDRESS
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final Report: 6/72 - 4/74
14. SPONSORING AGENCY CODE
5. SUPPLEMENTARY NOTES
6. ABSTRACT
Results of a demonstration of the feasibility and benefits of applying several
advanced wastewater treatment control strategies in an operational treatment plant
using a digital computer are presented in this report. The work was conducted in a
full size (35 MGD capacity) secondary treatment plant at Palo Alto, California.
Control strategies tested were for the secondary treatment portion of the process and
involved regulation of aeration tank dissolved oxygen (DO) and food for microorganism
ratio (F/M). Two variations of F/M ratio control were evaluated using respectively
air flow and a direct measurement of sludge respiration with an on-line respirometer
to estimate food (BOD). An extensive data collection program was incorporated which
allowed detailed statistical evaluation of each control algorithm with regard to
performance, effluent quality impact, operating costs, and reliability, comparison
was made to similar data collected during benchmark manual operation tests. Overall
results indicate digital control using advanced control concepts is feasible and that
demonstrable improvements in effluent quality are obtained. Direct operating cost
savings in the form of an 11% reduction in air use was also shown for DO control.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
. COSATI Field/Group
Automatic control, Waste treatment,
Dissolved gases, Oxygen, Sludge,
Activated sludge process, Instruments,
Computers, Data acquisition, Analyzers
Palo Alto (California),
Badger meter respiro-
meter, Astro ecology TOC
analyzer, IBM system/7,
Keene suspended solids
13B
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
165
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
155
U. S. GOVERNMENT PRINTING OFFICE. 1975-657-592/5362 Region No. 5-11
------- |