EPA-600/2-75-058
December 1975
Environmental Protection Technology Series
State of the Technology
SEMI-AUTOMATIC CONTROL OF
ACTIVATED SLUDGE TREATMENT PLANTS
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development,
U.S. Environmental Protection Agency, have been grouped into
five series. These five broad categories were established to
facilitate further development and application of environmental
technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in
related fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to
develop and demonstrate instrumentation, equipment and methodol-
ogy to repair or prevent environmental degradation from point
and non-point sources of pollution. This work provides the new
or improved technology required for the control and treatment of
pollution sources to meet environmental quality standards.
This document is available to the public through the National
Technical Information Service, Springfield, Virginia 22161.
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EPA-600/2-75-058
December 1975
State of the Technology
SEMI-AUTOMATIC CONTROL OF
ACTIVATED SLUDGE TREATMENT PLANTS
by
Carl A. Nagel
County Sanitation Districts of
Los Angeles County
Whittier, California 90607
Contract No. R803 055-01-0
Project Officer
Robert Smith
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental
Research Laboratory, U.S. Environmental Protection Agency,
and approved for publication. Approval does not signify that
the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or
recommendation for use.
IX
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Fred,
I recommend the following components for the A£I program:
I. Evaluate and demonstrate current technology
A. Programmable calculators
B. Desk top computers
C. Programmable logic controllers
D. Process controllers
II. Evaluate the need for automated analysis
A. Sludge settling velocity
B. Sludge blanket monitor
C. Wastewater treatability/toxic monitor
D. Sludge dewaterability
E. Sludge cake moisture analyzer
F. D.O. uptake rate
III. Evaluate proposed control strategies
IV. Training operators on instrumentation maintenance
V- A§I program self monitoring
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I. Evaluate and Demonstrate Current Technology
This component of the A§I program would evaluate and/or demon-
strate the use of devices that have had substantial technology
advancement in the past 5 years. These devices would include
programmable calculators, desk top computers, programmable logic
controllers, and process controllers. The potential use of these
devices is outlined as follows:
A. Programmable Calculators
These devices are capable of receiving a number of input
valves such as MLVSS, RAD-VS, and sludge blanket level, and
computing a given equation such as solids inventory. The device
is capable of retaining the program when shut off. Thus,
repetitive daily calculations can be performed more timely.
Current cost of these devices range from $100 to $500.
B. Desk Top Computer (Home Computers)
The desk top computer would analyze operational data similar
to the programmable calculator but have the additional advantage
of data storage. This allows the desk top computer to analyze
historical data (about one year data volume) for effluent
quality vs. operating parameter over a long time period. This
would be used by an engineer or class III operator to evaluate the
operating parameters of his plant. Current cost of these devices
are changing rapidly with the introduction of home computers.
Current price ranges from $2,000 to $10,000.
C. Programmable Logic Controllers
These devices are capable of performing relay logic (off/on),
timing and counting functions for process control. These functions
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cover 70 to 90% of all process control functions required at a
wastewater treatment plant. Some of these devices can interfere
with a common telephone and communicate with a central office.
Thus, they can be used for remote monitoring and process control.
Current cost of these devices are $5,000 to $10,000.
D. Process Controllers
These devices are capable of performing all the functions
of the programmable logic controller plus analog control (flow
control and D.O. control). These functions cover all but the
most exotic control functions required to operate a conventional
wastewater treatment plant. Current cost of these devices range
from $5,000 to $20,000.
II. Evaluate the Need for Automated Analysis
This component of the A£I program would evaluate the economic
and process reliability benefit of automating analysis that currently
can only be performed manually. This evaluation would be published
to inspire manufacturers to develop these instruments. Potential
areas of investigation include the following:
A. Sludge settling velocity (5 min. settling volume)
B. Sludge blanket
C. Wastewater Treatability/Toxic Monitor
D. Sludge dewaterability
E. Sludge cake moisture monitor
F. D.O. Uptake Rate
The method of implementation would be to manually perform the
analysis at a high frequency (1 hr.) and evaluate the economic and
process reliability benefit.
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III. Evaluate Proposed Control Strategies
This component of the A£I program would evaluate control strategies
that are proposed in the literature. This can be accomplished at
the Test and Evaluation Facility using existing pilot plant equip-
ment. Possible control stratagies that may be evaluated are as
follows :
A. Specific oxygen uptake rate.
B. Shifting from conventional activated sludge to contact
stabilization as organic load varies.
C. Use of conventional math models in process control.
D. Use of artificial intelligence for process control.
IV. Training Operators on Instrumentation Maintenance
A problem with operation of a wastewater treatment plant through
automation is maintaining sensor. In most cases the maintenance
requirement of a sensor is simply cleaning the probe. This
component of the A£I program would stimulate instrument manufacturers
to provide training on installation, operation, maintenance, and
application of their devices.
Program Self Monitoring
Self monitoring is a vital component of this program. The
program will conduct services of wastewater treatment plants to
determine the problem areas of automation. This will be accomplished
through both inhouse telephone surveys and contract surveys.
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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 environ-
ment—air, water, and land. The Municipal Environmental
Research Laboratory contributes to this multidisciplinary
focus through programs engaged in
• studies on the effects of environmental contaminants
on the biosphere, and
• a search for ways to prevent contamination and to
recycle valuable resources.
The County Sanitation Districts of Los Angeles County has been
a leader in development of efficient operating and maintenance
practices in the field of wastewater treatment. As part of
this effort, a number of semi-automatic control schemes have
been successfully developed. The purpose of this report is to
document the theory and engineering technology needed to apply
these new techniques. It is hoped that this report will provide
an incentive to encourage application of semi-automatic control
schemes in other wastewater treatment plants.
111
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ABSTRACT
This report documents the theory, design and operation of
continuous on-line instrumentation currently in use by the
County Sanitation Districts of Los Angeles County, California
and further describes computer applications which provide
daily operational calculations.
Instrumentation sections include Water Level Control of
Influent Pumping, Density Control of Primary Sludge Pumping,
and Process Air, Return Sludge and Waste Sludge Control in
Activated Sludge Plants. Theory, design, operation and main-
tenance requirements, and results are presented for each system.
A computer application system is described which provides
daily operational parameters to the operators and prepares
monthly summary of operations reports. A review of other
computer applications and a subroutine to compare effluent
characteristics with discharge limits is included.
This report was submitted in fulfillment of Contract Number
R 803 055-01-0, by the County Sanitation Districts of Los
Angeles County, under the sponsorship of the Environmental
Protection Agency. Work was completed as of June 1975.
IV
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CONTENTS
Page
Abstract iv
List Figures vi
List of Tables ix
Acknowledgments x
Sections
I Conclusions 1
II Recommendations 2
III Introduction 3
IV Influent Pumping - Water Level Control 7
V Primary Sludge Pumping - Density Control 20
VI Activated Sludge - Process Air Control 51
VII Return Activated Sludge - Flow Control 75
VIII Waste Activated Sludge - Flow Control 102
IX Computer Control Applications 117
X Appendix - Example of Monthly Report Summarizing
All Data and Calculations 182
v
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FIGURES
No. Page
1 Schematic of Liquid Level Control System 10
2 Pump Sequencing and Control Point Levels 12
3 Wet Well Level VS. Plant Flow Rate 17
4 Wet Well Level VS. Plant Flow Rate 18
5 Diurnal Flow Pattern 23
6 Diurnal and Seasonal Influent Suspended
Solids Pattern 24
7 Components of Typical Nuclear Density Gauge 29
8 Control Panel with Amplifier and Controller -
Recorder 30
9 Amplifier and Indicating Meter 31
10 Joint Water Pollution Control Plant
Sedimentation Tank Layout 33
11 Unit of Sedimentation Tanks with Pump, Meter,
and Wet Well 34
12 Horizontal and Vertical Orientation of Density
Gauge 35
13 Schematic of Density Control System 37
14 Density Gauge Recording - Gassing Sludge 40
15 Density Gauge Recording - Water Leak 40
16 Density Gauge Recording - Vacuum 42
17 Density Gauge Recording - Erratic Reading 42
18 Density Gauge Recording - Density Control 43
VI
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FIGURES - Continued
No. Page
19 Sample Encapsulator 45
20 Density Gauge Recording - Noise Band 43
21 Plant Flow, Process Air Flow, COD Loading 56
22 Oxygen Supplied Vs. Dissolved Oxygen Level 57
23 Schematic of Cam Programmer Control 59
24 Schematic of Air/Flow Control 62
25 Schematic of Dissolved Oxygen Control 63
26 Dissolved Oxygen Profile 65
27 Plant Flow, Process Air Flow, Dissolved Oxygen 68
Level
28 Instrument Flow Diagram 72
29 Schematic of Return Sludge Flow Control 77
30 Schematic of Secondary Treatment Flow Distribution 80
31 Sludge Volume Index Plot 83
32 Suspended Solids and Light Transmission Vs. Depth 86
33 Suspended Solids and Light Transmission Vs. Depth 87
34 Percent Light Transmission Vs. Return Sludge
Suspended Solids 88
35 Light Transmission at Various Depths 91
36 Light Transmission at Various Depths 92
37 Light Transmission at Various Depths 93
38 Light Transmission at Various Depths 94
39 Light Transmisstion and Probe Actuation 97
40 Light Transmission and Probe Actuation 98
41 Schematic of Mixed Liquor Wasting 105
42 Schematic of Return Sludge Wasting 108
vii
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FIGURES - Continued
No. Page
43 Diurnal Variation in Return Sludge Concentration 111
44 Schematic of Waste Activated Sludge Control System 113
45 Water Renovation Plant Data Management System 122
46 WRQDMS - Schematic Diagram of On-line Programs 123
47 Example of Raw Data Collection Sheets 124-128
48 Collection Sheets for Solids Handling Unit
Processes 130
49 Printout of a Status Transaction 131
50 Printout of Update Transaction 133
51 Typical Store Printout 134
52 Schematic Flow Diagram of Thickening and Anaerobic
Digestion Process at the District 26 & 32 WRP's 148
53 Printout of Typical EFFCMP Transaction 160
54 Example of Stored Effluent Compliance Limits 173
55 EFFCMP Printout When Effluent Compliance
Violations Occur 174-175
56 Printout of Daily Operational Data and
Calculations 176
57 Printout of Solids Handling Data and Calculations 177
58 Date Record Management Program - Typical Printout 179
59 Operational Data Management Program - Typical
Printout 180
Vlll
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TABLES
No. Page
1 Summary of Influent Pump Station Data 14
2 Raw Sludge Composite Samples 26
3 Air Control Methods Used 55
4 Response of Process Air to Operating Variables 71
5 Long Beach Plant Operation Parameters 90
6 Percentage of Probe Actuation at Various SVI's 99
7 Loading Calculation Formulas 136
8 Solids Calculation Formulas 137-139
9 Aeration Time Calculation Formulas 142-143
10 Cell Residence Time Calculation Formulas 145-146
11 Solids Handling Calculations 151-157
12 Effluent Compliance Daily Calculation Formulas 161-162
13 Effluent Compliance 7-Day Average Calculation
Formulas 164-166
14 Effluent Compliance 30-Day Average Calculation
Formulas 167-172
IX
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ACKNOWLEDGMENTS
This report was prepared for the Advanced Waste Treatment
Research Laboratory (now the Wastewater Research Division,
Municipal Environmental Research Laboratory) of the U.S.
Environmental Protection Agency. The contributions of the
following individuals in gathering the information and
preparing the text are gratefully acknowledged.
R.T. Haug
R.S. Easley
R.C. Caballero
E. Motokane
S. Brun
L.F. Bednorz
W.G. Schmitz
D.E. Schulenburg
x
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SECTION I
CONCLUSIONS
The greater emphasis being placed on protection of the environ-
ment has substantially increased the number and complexity of
treatment plants. More care in control of various plant
processes is necessary to meet present and future discharge
standards.
A variety of automatic and semi-automatic instrument control
systems have been used successfully for a number of years. These
systems aid in stabilizing processes, reduce personnel require-
ments, and improve the efficiency of treatment plants.
These instrument systems have proven to be reliable and prac-
tical. They are suitable for use in plants of any size and
require only a reasonable amount of maintenance.
To reduce operator time and improve efficiencies, a computer
system, leased or owned, can be used to great advantage. Human
errors are largely eliminated and up-to-date information is
readily available for review by anyone concerned with the
operation.
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SECTION II
RECOMMENDATIONS
This program was limited to the description and documentation
of five existing instrument control systems. It was not within
the scope of this project to present a literature review of all
instrument systems commonly used nor to develop or test new
systems. It is recommended, however, that development of new
systems be supported to further enhance the reliability of
treatment processes.
It should be noted that the systems described in this report have
been in use for a substantial period of time, their reliability
has been proven, and they can be used now in most plants with a
minimum of modification being necessary.
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SECTION III
INTRODUCTION
GENERAL
Increasing emphasis on efficient treatment and disposal of
municipal wastewater has greatly increased the number and
complexity of activated sludge treatment plants.
While in most cases the planning and design leading to the
construction of new treatment plants have involved extensive
engineering work, it is not uncommon that after completion
of construction and start-up of the plant the daily operation
of the plant is left almost entirely in the hands of the
operator. Thus, the responsibility of the plant achieving
the design objective rests with the operator.
Most operators, however, have only a limited amount of time
they can devote to actually operating the plant. For many,
their time is also spent performing maintenance, gardening,
laboratory tests, and other miscellaneous functions. Also,
the educational backgrounds among operators are quite diverse.
Some easily grasp the concepts necessary to operate the plant,
others, do not.
For the above reasons it is desirable to have methods to
help the operator properly run the plant. Devices that
will allow the operator to monitor variable constituents,
calculate important operating parameters, set and maintain
proper process controls, and activate alarms will help
insure proper operation. However, the installation of
such equipment does present certain problems. Sophisticated
equipment is subject to frequent breakdowns, and mainte-
nance requires highly trained individuals. Also, instal-
lation of such equipment can lead the operator to over-rely
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on the instrument and avoid thinking about the total operation
of the plant and the interrelationships existing among the
various processes.
LOCATION
This project was conducted by the County Sanitation Districts
of Los Angeles County, California. The Districts serve the
sewage and refuse disposal needs of nearly 4 million of the
over 7 million people in Los Angeles County. There are now
a total of twenty-seven Districts, the first established in
1923. They are governed by a Board of Directors made up of the
mayors and county supervisors whose jurisdictional areas are
involved. The Districts stretch from the eastern border of the
City of Los Angeles to Pomona and from Long Beach to Lancaster
and include a total of 71 cities. Combining their efforts
under a single administration has permitted the development
of an expert technical staff capable of attacking wide ranging
problems on a regional basis.
At present, the major Districts' facility for treatment of
municipal wastewaters is the Joint Water Pollution Control
Plant (JWPCP) located in Carson. The plant is currently
treating over 1.25 x 10 cu m/day (330 mgd) of wastewater by
primary sedimentation and should have secondary treatment
facilities added by 1977. The treated wastewaters are dis-
charged through a sophisticated outfall system two miles off
Palos Verdes Peninsula. Most of the organic solids removed
during treatment are sold as fertilizer base.
In addition to the Joint Water Pollution Control Plant, the
Districts also operate and maintain ten smaller secondary
plants. Two of these are in the Antelope Valley north of
Los Angeles. One plant, operating at about 13,626 cu m/day
(3.6 mgd) and serving the community of Lancaster, utilizes
oxidation ponds for secondary treatment. There is no percolation
to the underground in this area because of the extreme tightness
of the alkali soil. A tertiary treatment facility of 1893 cu m/day
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(0.5 mgd) capacity was constructed in 1970 to remove nutrients
and algae from the oxidation pond water to permit its use in
recreational lakes to be operated near Lancaster by the
County Department of Recreation and Parks. The other plant,
serving the community of Palmdale, treats about 4542 cu m/day
(1.2 mgd); the water from the oxidation ponds is sold for
irrigation of alfalfa.
An activated sludge plant with a capacity of 18,925 cu m/day
(5 mgd) treats the sewage from District No. 26 in the Saugus
area. The present flow of about 12,112 cu m/day (3.2 mgd)
from this plant is discharged into the Santa Clara River Channel
and percolated into the underground to recharge the aquifers.
In nearby Valencia, Sanitation District No. 32 operates a
smaller but similar plant to that of District No. 26. The
flow of about 4542 cu m/day (1.2 mgd) is also discharged to
the Santa Clara River.
District No. 28 operates and maintains a small activated sludge
plant in the vicinity of La Canada to treat the sewage from
the Angeles Crest Country Club and surrounding residential area.
The effluent from this plant makes a substantial portion of the
irrigation water for the golf course.
The remaining five Districts' plants are located in the Los
Angeles Basin and employ the activated sludge process for
secondary treatment. All of the Districts in this geographical
area are members of a Joint Outfall Agreement which provides
for joint construction, operation, and maintenance of trunk
sewers, pumping plants, and treatment works. The maintenance
and operation of the joint outfall system, including upkeep
and repair costs, are shared jointly by the various districts
having ownership. These costs are proportioned according to
the amount of flow contributed by each individual District.
Each of the plants in this Los Angeles Basin grouping are
situated adjacent to a major trunk of the jointly owned trunk
sewer system. None of these plants has solids processing
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facilities; all waste products, skimmingsf primary and waste
activated sludges are returned to the trunk sewer for transport
and later recovery and processing at the Joint Water Pollution
Control Plant.
The Districts' plants involved in this system, with their
respective designed capacities are as follows;
1. Pomona Water Renovation Plant,
36,336 cu m/day (9.6 mgd)
2. San Jose Creek Water Renovation Plant,
1.4 x 105 cu m/day (37.5 mgd)
3. Whittier Narrows Water Reclamation Plant,
47,312 cu m/day (12.5 mgd)
4. Los Coyotes Water Renovation Plant,
1.4 x 105 cu m/day (37.5 mgd)
5. Long Beach Water Renovation Plant,
47,312 cu m/day (12.5 mgd)
OBJECTIVES
The plants operated by the County Sanitation Districts of Los
Angeles County (LACSD) have a variety of control devices which
have proven to be useful in properly operating the plants. It
is believed that others can benefit from the knowledge gained
in this operations experience.
Accordingly, two major objectives have been pursued:
1. Documentation of the theory, design, and operation of
continuous on-line instrumentation currently in use by
LACSD.
2. Documentation of the computer applications the LACSD has
developed to provide daily operational parameters,
calculations, and monthly summary of operations reports.
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SECTION IV
INFLUENT PUMPING - WATER LEVEL CONTROL
INTRODUCTION
Elevations of all but two of the secondary treatment plants
on the LACSD Joint Outfall System are above trunk sewer
elevations serving them. This necessitates use of influent
pump stations to lift wastewater out of the trunk lines and
into the plants. These pump stations are important elements
in the treatment process. If they fail, other processes are
useless with no flow to treat.
Most of the pumping plants in the LACSD system are designed
with variable speed pumps and liquid level control These
include 10 treatment plants and 19 sewer lift stations. In
general, water surface elevations in the incoming sewers are
maintained near normal depth by varying pump speed with depth
of flow. Although this proportional relationship between depth
and pump speed does not exactly produce normal depth for all
flows, it approximates it closely enough to avoid adverse
effects caused by excessively high or low velocities in the
sewer.
FACILITIES AT THE LONG BEACH WATER RENOVATION PLANT
The Long Beach Water Renovation Plant was the site of data
collection to document response of the variable speed pumps
to changes in the wet well water level. This station contains
four pumping units. Two smaller units each consist of a
Fairbanks Morse 25.4 c m (10 inch) centrifugal sewage pump,
Watson Flexible shafting, an Ideal Electric motor and magnetic
drive, and a liquid level control panel. The two larger units
each consist of a Fairbanks Morse 76.2 c m (30 inch) centrifugal
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sewage pump, Watson flexible shafting, an Ideal Electric motor
and magnetic drive, Western Gear right angle gear box, and a
Liquid Level Control panel. Currently only the two smaller
units are operated since plant flow is not yet sufficient for
efficient operation of the larger units.
The Plant is serviced by three influent trunk sewers which
discharge into a junction box at the head of the plant. Sewage
then flows from the junction box through a 175.26 c m (69 inch)
outfall to a wet well where it is pumped into the plant. The
influent trunk sewers are of different sizes and slopes and,
as such, it is impossible to maintain normal depth in all three
under all flow conditions. Thus, the previous statement that
pump speed is varied to maintain normal depth in the incoming
sewer can only be true when there is a single influent sewer.
However, the main purpose of sensing a varying wet well water
level is to avoid excessively low or high flow velocities in
the sewers. It is not essential to maintain exact normal depth
but only to maintain water elevations within reasonable limits.
Pump speed is varied by controlling the output speed of the
magnetic drives. This can be accomplished either manually or
automatically by use of the liquid level control system. Under
manual operation, start and stop of each pump is controlled by
the plant operator through use of a sequence selector switch.
A pump will start when its corresponding sequence selector
switch is set to the "Hand" position. Pump speed is regulated
by a manual potentiometer and indicated by a tachometer. Each
pump motor has an adjustable (1 to 600 seconds) time delay relay
to prevent a successive motor start until the desired time delay
on energization of the motor has elapsed. Each variable speed
drive also has a time delay relay to allow a sufficient time
interval to elapse after the energization of each corresponding
motor so that each motor shall start under no load and shall
attain full speed before the start of each variable speed drive.
LEVEL CONTROL SYSTEM
The level control system is used to control the influent pumps
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so that the rate of discharge from the pumping station is
approximately equal to the varying rate of sewage inflow.
Liquid level in the influent pump wet well is automatically
sensed and controlled as described below. Level control in
the wet well is initiated by means of proper pump sequencing
and by varying the influent pump speed. The system is capable
of sequencing pump operation and varying the speed of all
pumps as necessary to pump a variable station flow without
storage in the wet well.
A schematic diagram of the liquid level control system is shown
in Figure 1. Major components of the system are the level
sensor and transmitter, liquid level contrpl unit, and the
motor/variable speed drive units used to power the pumps.
Primary intelligence for the level control system is obtained
from an electronic differential pressure transmitter or trans-
ducer. This unit is used to sense the rising and falling
liquid level in a stilling well which is directly connected
to the influent wet well. Pressure sensed in the stilling
well is converted to a 4-20 milliampere direct current control
signal, proportional to the stilling well water level.
The liquid level control unit receives the control signal
generated by the differential pressure transmitter. This
signal is used as a pilot signal for operation of the control
equipment. These operations include indication of the liquid
level in the wet well, initiation of start and stop functions
for all pumps, modulation of pump speed, and actuation of alarms
for high and low water levels in the wet well.
Starting and stopping of each pump is initiated by individual
current alarms which use the 4-20 ma signal produced by the
level transmitter. Current alarms have calibrated hand dials
for adjusting the trip setting and deadband setting.
Two time delay relays (adjustable from 1 to 600 seconds) are
provided for each pump unit. The first relay is actuated by
a motor stop and prevents a successive motor start until the
9
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LIQUID
LEVEL
INDICATOR
PUMP
SEQUENCING
AND SPEED
MODULATION
HIGH AND LOW
WATER LEVEL
ALARMS
STILLING
WELL
LIQUID LEVEL
CONTROL UNIT
4 20 ma SIGNAL
PROPORTIONAL TO
STILLING WELL
WATER LEVEL
DIFFERENTIAL
PRESSURE
TRANSMITTER
Ar
WET WELL
V
n
FIGURE I SCHEMATIC DIAGRAM OF THE LIQUID LEVEL CONTROL SYSTEM
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desired time delay has elapsed. This is designed to prevent
rapid starting and stopping of the pump. The second relay is
actuated by a motor start and delays energization of the
variable speed drive. This allows the motor to attain full
speed and start under a no load condition.
AUTOMATIC OPERATION
Pump sequencing and control points levels (based on submergence
over pump suction as well as elevations based on plant datum)
are shown in Figure 2.
These points are approximate liquid levels at which control
functions are initiated together with the level excursions
available for control of speed modulation for the various
pump combinations throughout the operating ranges. Step numbers
in Figure 2 are pump sequencing steps applicable to any of the
four pumps which are to be selected by manually positioning
the sequence selector switches.
Assume plant flow at zero and the liquid level in the influent
pump wet well below the start setting of Step 1. As flow begins
and the level rises, the start setting of Step 1 starts the
first pump at minimum speed and a rising level causes the pump
speed to increase in linear proportion to the rise in level.
Operation continues in this manner until the pump is operating
at maximum speed.
If the wet well level continues to rise, the start setting of
Step 2 starts the second pump and both pumps are adjusted to
equal speed so that each will discharge one-half of the station
flow. If the level continues to rise, both pumps increase in
speed equally in linear proportion to the rise in level until
both pumps are operating at maximum speed. Manual selection
of the same size pumping units for Steps 1 and 2 is considered
normal operation.
Continued increases in wet well water level signal sequential
starting of a third and fourth influent pump in the same manner
as that described above. At present, however, only two influent
11
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PLANT DATUM
ELEVATION FEET
SUBMERGENCE ON PUMP
SUCTION FEET
6.0
5 .0
4.0
3.0
2.0
1 .0
0.0
1 .0
2.0
3.0
4.0
HIGH LEVEL
- ALARM _
.STEP 4 STOP!
^STEP 3 STOP.
,STEP 2 STOP.
fSTEP
LOW
STOPI,
LEVEL
„ ALARM
-j
1
p
FALLING WET
WELL
LEVEL
IO.O
9 0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
I.O
0.0
, STEP 4 START
STEP 3 START
^STEP 2 START
STEP I START
ri
RISING WET
WELL LEVEL
"
4 PUMPS ATMAX. SPEED
4 PUMPS AT MIN. SPEED
3 PUMPS AT MAX. SPEED
3 PUMPS AT MIN. SPEED
2 PUMPS AT MAX. SPEED
2 PUMPS AT MIN. SPEED
I PUMP AT MAX. SPEED
I PUMP AT MIN. SPEED
FIGURE 2
PUMP SEQUENCING ELEVATIONS
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pumps are required to meet the peak flow rate.
The pumps operate in reverse order when wet well level decreases.
The stop settings of Steps 1 through 4 are set so that the level
at individual pump stops will be lower than the levels at starts.
This is to prevent accidental pump shutdown in response to
momentarily lowered water levels experienced following pump
starts. The last pump stops and does not operate (except by
manual control) when the level falls below the stop setting
of Step 1.
EXPERIMENTAL RESULTS
A recorder was placed in the control panel of the influent
pump station to continuously record wet well water level. The
control signal provided by the differential pressure transducer
was used as input to the recorder. This enabled wet well water
levels to be correlated with pump sequencing and plant flow rate.
Four weeks of data were obtained to document the influent pump
control system.
A summary of the experimental findings is presented in Table 1.
Incoming sewage flows were sufficient to maintain at least one
operating pump at all times, whereas two pumps were required to
carry the peak flow. Wet well water levels initiating sequencing
of the second influent pump averaged 2.19 meters (7.2 feet)
(above pump suction) compared with the desired set point of
2.13 meters (7.0 feet). The actual set points are adjustable
and the difference only reflects a slight error in adjustment.
Variations in wet well levels initiating pump sequencing were
extremely small. The difference between the smallest and
largest values observed during the 30-day study period was only
1.52 c m (0.6 inch). Thus, while the set point adjustment was
slightly in error the water elevation which initiated the start
of the second pump was reproducible, varying insignificantly
during the study period.
The same comments apply to the wet well water level used to
signal the stop of the second influent pump. While water level
13
-------
Table 1
SUMMARY OF DATA COLLECTED AT LONG BEACH WATER
RENOVATION PLANT INFLUENT PUMP STATION
Average
Variable Value a
Wet well level at start 7.20
of second influent pump
Plant flowrate at start 6.10
of second influent pump
Wet well level at stop 6.95
of second influent pump
Plant flowrate at stop 7.40
of second influent pump
Standard
Deviation Range b
0.022 0.05
0.78 2.60
0.026 0.10
0.50 2.00
a All elevations in feet above pump suction and flowrates
in mgd.
b Range is defined as the difference between the smallest
and largest value.
14
-------
initiating pump stop was slightly above the desired set point
value (2.21 meters compared with 2.01 meters) (6.95 feet
compared with 6.60 feet) the range of values varied by only
3.05 cm (1.2 inch).
While water levels initiating pump sequencing were constant
during the study period, corresponding pumped flow rates were
not constant. For example, plant flow rate at the start of the
second influent pump averaged 23,088 cu in/day (6.1 mgd) but
varied from a low of 17,789 cu m/day (4.7 mgd) to a high of
27,630 cu m/day (7.3 mgd). Plant flow rate at the stop of the
second influent pump varied in a similar manner.
Variation in pumped flow rate at the time of pump sequencing
was due to two causes. First, the proportional controlling
system regulates only pump speed and not pump output. Thus,
at any particular wet well water level, one value of pump
speed is called for. Should wet well water change, pump speed
will change in proportion to changing water level. But at any
given water level pump speed is constant. There is no reset
function in the influent pump control system. Second, at a
given rpm, flow rate is determined by the total dynamic head
against which the pump works. Dynamic head would normally be
a constant value at a given flow rate except for the fact that
rags and other debris tend to collect in the volute at the
suction side of the impeller. This increases headloss which
decreases pump output at a given rpm. Thus, variation in
observed flow rates at the time of pump sequencing reflects
the degree of ragging at the pump suction.
Routine plant operation calls for deragging of influent pumps
whenever the capacity appears to be lower than normal. During
the test period, this required deragging on an almost daily
basis (21 times during the 30-day study period with a labor
expenditure of approximately one-half hour per incident). Not
only is this a nuisance as far as a plant operator is concerned,
it can affect proper pump sequencing. Following termination of
the test period, the practice of routine wet well cleaning was
15
-------
initiated. This is accomplished during the low flow period by
manually pumping the wet well to a point below the normal low
level point. In this manner, floatables are removed preventing
large accumulations of materials which might be drawn into a
pump at a later time causing partial stoppages. Since initia-
tion of this procedure on a daily basis, no deragging of the
pumps has been necessary during a continuous 90-day period.
Ideally, startup of a second influent pump should not pull down
the wet well water level to such an extent that the stopping
set point is exceeded. This would result in repeated starting
and stopping of the second pump. The time delays, of course,
would protect the equipment from too rapid a start and stop.
Likewise, stopping of the second influent pump should not cause
the wet well level to rise to the point where it again signals
for start of the second pump. In other words, one pump at
maximum speed should have nearly the same capacity as two pumps
at minimum speed.
Plant flow rate and wet well water levels during pump sequencing
are shown in Figures 3 and 4. Referring to Figure 3, as flow
increased in the morning hours, the wet well level increased to
2.19 meters (7.2 feet) at which time the second pump started.
This resulted in a sudden increase in flow rate with corresponding
drawdown of the wet well. Lowered wet well levels signalled for
reduced pump speed and eventually inflow and outflow from the
wet well were matched. During the course of the study the wet
well was never drawn down to the point where shutoff of the
second pump occurred.
Again referring to Figure 3, as flow decreased in the early
morning hours the wet well was eventually drawn down to the
point where the second pump stopped. This resulted in a
momentary decrease in flow rate and corresponding increase
in wet well level. If the remaining pump was free of rags and
other debris, it could carry the entire flow and prevent restarting
of the second pump. However, if the intake was clogged the single
pump would be unable to carry the incoming flow- Wet well level
16
-------
UJ 0)
80
70
m so
$*
50
2nd PUMP
STOP
2nd PUMP
START^
12
Q
O
I
O
i
\
AM
AM
AM
AM
10
AM
JULY 31, 1974
FIGURE 3
WET WELL WATER LEVEL AND PLANT FLOWRATE LONG BEACH
WATER RENOVATION PLANT INFLUENT PUMP STATION
-------
— o
UJ
80
70
60
•sn
2nd PUMP
/"STOP
ck
^^
2nd PUMP
^ RESTARTS
^^
^
2nd PUMP
START"^
^x*
>
oo
12
10
O
2 8
Q 6
-PUMP RESTARTS
AM
AM
AM
JULY 28,1974
AM
10
AM
WET WELL WATER LEVEL AND PLANT FLOWRATE LONG BEACH
FIGURE 4 WATER RENOVATION PLANT INFLUENT PUMP STATION
-------
would rise to set point level signalling restart of the second
pump. The flow rate and wet well levels corresponding to this
situation are shown in Figure 4. Restarts occurred approxi-
mately 50 percent of the time during the study period. About
10 percent of the time two restarts were required before flow
rate was reduced to the point where a single pump was sufficient.
It should be emphasized that pump restarts are not a serious
problem in the sense of affecting pump station operation or
damaging equipment. Too rapid starting and stopping is prevented
by the time delay relays. However, it is probably wise to avoid
restarts as much as possible since they waste electrical power
and cause a certain amount of equipment wear. Routine cleaning
of the wet well or increasing the elevation difference between
start and stop set points would avoid the problem.
19
-------
SECTION V
PRIMARY SLUDGE PUMPING - DENSITY CONTROL
INTRODUCTION
Benefits of Thickening
Sludge thickening occurs naturally in the sludge blanket of a
primary sedimentation tank. It is desirable to control this
thickening because of the benefits to many sewage treatment
plant processes:
1. Fewer gallons are pumped to transfer the same mass of
suspended solids.
2. The denser the raw sludge added to the digester, the
smaller the digester volume required.
3. The denser the raw sludge, the smaller is the amount of
energy required for maintaining digester temperatures.
4. Dewatering filters operate more efficiently when fed by
a sludge of high consistency.
5. Material transferred to storage is more concentrated,
reducing the storage volume required.
Basis for Intermittent Pumping
Suspended solids settle continuously in a primary clarifier and
accumulate in the sludge blanket. The sludge blanket must be
maintained at an adequate level to promote proper thickening.
This is accomplished by withdrawing the sludge out of the tank's
hopper at the same rate that it accumulates, allowing only the
thickest sludge from the bottom of the blanket to be pumped.
The following restrictive parameters have evolved from standard
practice and from the basic considerations in primary sludge
20
-------
pumping design:
1. "Sludge withdrawal piping generally has a minimum diameter
of 15.24 to 20.32 cm (6 to 8 in.)." * Small pipe will
become clogged.
2. "Sludge velocities between 1.52 and 2.44 mps (5 and 8 fps)
are, in general, found to be satisfactory." The minimum
acceptable to prevent settling in the lines is 0.9 mps
(3 fps).
3. The rate of flow, tank design, and wastewater character-
istics influence the tank efficiency and thus, the rate
of accumulation of sludge within the tank. At the JWPCP,
the average accumulation rate for a rectangular primary
clarifier with a surface area of 502 sq m (5400 sq ft)
varies from 1.26 to 2.02 £/s (20 to 32 gpm) (average sludge
consistency of 5.5% total solids).
The above restrictive diameter, velocity, and suspended solids
removal rate parameters have made intermittent pumping the most
practical solution over the years. In this manner, the parameters
are fulfilled by pumping the sludge every 20-40 minutes (based on
average accumulation rate).
Intermittent pumping may be performed manually but this practice
is extremely wasteful of the operator's time and the pumping
period may occur at a time when the operator is not at the plant
site or is occupied elsewhere. In addition, the results
obtained by manual pumping usually are inconsistent and extremely
variable depending upon which operator is on duty.
In small treatment facilities where the number of sedimentation
basins is limited, reasonable control of sludge pumping can be
effected with simple timer controls. In this situation, it is
important that timer settings be calculated carefully and that
positive displacement collector pumps be employed so that the
volume of sludge pumped per unit time remains fairly uniform
*
p 200 - WPCF Manual of Practice No 8 - Sewage Treatment Plant
Design, 1959
21
-------
regardless of sludge density. The timers can control the
pumping from one or a series of settling basins.
For larger treatment works, it is more efficient to use larger
capacity centrifugal pumps and to use a single pump to serve
a series of sedimentation basins. In this application, nuclear
density gauges, in conjunction with timer controls, provide an
effective method of controlling intermittent sludge pumping.
As described later, the timer controls initiate the pumping
process and regulate certain segments of the pumping cycle while
the density gauge terminates the pumping process and provides
a continuous monitoring of the solids concentration allowing
the operator to observe density changes as they occur and to
adjust the timer settings as required.
Regardless of which of the above two automatic methods of
controlling intermittent sludge pumping is used, the basic timer
settings depend on the accumulation rate, which is a function
of the following variables:
1. Diurnal and seasonal flow. Figure 5 shows the diurnal
flow pattern for the Joint Water Pollution Control Plant,
a 541 cfs (350 MGD) primary facility operated by the Los
Angeles County Sanitation Districts.
2. Diurnal and seasonal influent suspended solids. Figure 6
shows the seasonal variation of influent total solids for
the JWPCP in 1973.
3. Diurnal and seasonal sludge settling and thickening
characteristics.
The success of timer control alone has been in treatment plants
where the timer settings have been carefully calculated and
adequate monitoring is provided. Its success also has been in
treatment plants where the raw sludge density is unimportant,
separate sludge thickening is provided, or where large variations
in sludge density can be tolerated.
Density monitoring and control provides a short response time to
fluctuations in the diurnal accumulation rate. As a result, the
22
-------
to
150
0000
0400
0800 NOON 1600
TIME OF DAY , hrs
2000
2400
FIGURE 5
TYPICAL DAILY FLOW AT THE JWPCP
-------
to
IJB
1.6 H
•S 1.4
o
Q.
12
1.0
c
£ .8
in
.6 -
.4 -
.2H
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
1973
FIGURE 6
SEASONAL VARIATION OF INFLUENT SOLIDS AT THE JW.PCP
-------
total volume of sludge pumped is reduced. Its application has
been at the JWPCP where large variations in sludge density can
not be tolerated in achieving efficient digester capacity
utilization. A brief discussion of the digestion system and
controls is included at the end of this section.
At the JWPCP, the sludge is pumped from three sedimentation
tank batteries to two raw sludge transfer stations. Table 2
summarizes 24-hour composite samples from these two stations
during part of 1974. The differences in sludge densities
between stations reflect the differences in accumulation rates
and thickening characteristics of the sludge.
OPERATION PROCEDURES
Adjusting Timer Settings - Timer Control Only
The timer settings are adjusted to pump a high percent total
solids and at the same time to prevent gassing (rising sludge)
in a tank.
Indirectly, the operator controls the sludge blanket level by
his timer changes. The sludge blanket level that promotes
optimum thickening is a variable which depends upon the sludge
holding time in the blanket. This holding time must not exceed
the minimum time required to produce gassing (rising sludge) in
the tank.
Calculations based on suspended solids removals which have been
determined on a diurnal pattern can be made to determine the
rate at which sludge accumulates in the tank. The timer settings
are then adjusted to pump from each tank hopper a volume of sludge
of the desired density equal to the volume of sludge that has
accumulated in the tank during the same period. With occasional
monitoring of the sludge blanket level and visual observation of
the tank surface, minor adjustments of the timer settings can be
made to correct for lack of sufficient sludge blanket, excessive
sludge blanket or sludge bulking which has resulted from gasifi-
cation.
25
-------
TABLE 2
MEASURED RAW SLUDGE TOTAL SOLIDS
FROM TRANSFER STATIONS AT THE JWPCP
March-August, 1974
Week
Ending
3-15
3-22
3-29
4-5
4-12
4-19
4-26
5-3
5-10
5-17
5-24
5-31
Percent Total Solids
Raw Sludge
Transfer
Station #1
6.2
5.8
5.6
5.5
5.8
5.6
5.5
5.7
5.5
5.6
6.0
5.6
Raw Sludge
Transfer
Station #2
5.3
5.6
5.5
5.7
5.3
5.4
5.3
5.0
5.0
5.2
5.0
4.9
Week
Ending
6-7
6-14
6-21
6-28
7-5
7-12
7-19
7-26
8-2
8-9
8-16
8-23
Percent Total Solids
Raw Sludge
Transfer
Station #1
5.4
5.5
5.4
-
5.6
5.3
5.4
5.4
5.4
5.5
5.5
5.7
Raw Sludge
Transfer
Station #2
5.3
5.3
5.3
-
5.2
4.9
4.9
5.2
5.2
5.1
5.1
4.7
26
-------
For example, if the analyses are made on 4-hour composites, the
approximate accumulation rate for each individual period can be
determined by the following formula:
Accumulation rate (gal per period)
= Dry suspended solids removed (mg/1) x Flow (MGD/Tank)
Percent consistency (decimal) x 60 (min/hr)
x 4 hrs/period
(24 hrs/day)
The control timers are then set so that the volume pumped during
the period equals the volume accumulated during the same period.
Adjusting Timer Settings with Density Controls
With density control, a timer is used to regulate the pump "off"
time rather than the pump "on" time. The pump "off" time is set
to permit sufficient accumulation of sludge so that density
control can be the dominant factor.
At the JWPCP, three separate trunk sewers with different flows
and suspended solids concentraions enter the plant. As a result,
the accumulation rates in the three sedimentation tank batteries
(El, E2, E3) are different. Shown below are the average 24-hour
per day accumulation rates (based on 5.5% total solids) entering
JWPCP during the period February - May, 1974.
Average Accumulation Rate (gpm)
Time Period El E2 E3
Feb - May, 1974 22 32 28.5
DESIGN
General
The sludge pumping control system described in this report
utilizes nuclear density gauges. Ultrasonic density gauges
are also available but the LACSD have no operational experience
in their application.
Description of Nuclear Density Gauges
The principle of operation is based upon the fact that gamma
radiation is absorbed as it passes through various materials
27
-------
and that this absorption is a function of the density of the
material.
The components of a common gauge are shown in Figure 7. A
source of gamma radiation (Cesium-137) is placed on one side
of the pipe and a measuring cell, or detector, on the opposite
side. The measuring cell converts the variable radiation field
produced by changes in density directly into an electrical
current. This current signal is then amplified and transmitted
to a recorder-controller. Figure 8 shows that both the amplifier
and recorder-controller are mounted in the same control panel
at the JWPCP.
The output of the amplifier is also displayed on its front panel
by an indicating meter as shown in Figure 9. In addition, the
amplifier has several operating controls located on its front or
side panels. Among these are the following (exact names vary
between manufacturers):
1. Zero Suppression- This control allows adjusting the
beginning point of the measurement. The "residual" current
at the reference specific gravity is nullified by a
compensating current of opposite polarity.
2. Time Constant - This control permits obtaining a balance
between the noise band and the process rate of change. The
noise band (pen wipe on a recorder) indicates the random
fluctuations of the meter reading and is caused by the
statistical variations in the emissions of the radioactive
source.
3. Calibration - This control adjusts the full scale sensi-
tivity of the amplifier.
4. Recorder - This control adjusts the amplifier output to
the recorder.
5. Check Zero - This control allows adjusting instrument
electrical zero.
The recorder is of the two-pen type with set point indicator,
as shown in Figure 9. The inner pen records sludge density
28
-------
RAW SLUDGE TO
BE MEASURED
RADIOACTIVE
SOURCE HOLDER 1-1
: T
ED
X
0
ft
'/st
AMPLIFIER
Hi
t
*^\ 1
I MEASURING RECORDEF
^ CELL CONTROLL
FIGURE 7
COMPONENTS OF A TYPICAL
NUCLEAR DENSITY GAUGE
29
-------
©i©i®i@i©i©i©
INDICATING
LIGHTS
RECORDER
CONTROLLER
TIMERS
AMPLIFIER AND
INDICATING
METER
FIGURE 8 TYPICAL SEDIMENTATION UNIT CONTROL
AT THE JWPCP
PANEL
30
-------
FIGURE 9
CLOSE-UP VIEWS OF RECORDER-CONTROLLER
(ABOVE) AND DENSITY GAUGE AMPLIFIER (BELOW)
31
-------
just as it is displayed on the amplifier indicating meter while
the outer pen records collector pump on and off time, see
Figure 20. The set point indicator can be set for any density.
Both recorder and indicating meter are calibrated in percent
total solids (0-10%).
Description of JWPCP Pumping System
The JWPCP has 52 sedimentation tanks arranged into ten pumping
units of four to six tanks each, see Figure 10. Each tank is
equipped with a draw off valve which consists of a gate valve
operated by an air piston. The sludge draw off lines from the
individual tanks in a unit are manifolded together and connected
to a single collector pump, as shown in Figure 11. Each centri-
fugal, nonclog pump provides a 6.1-7.6 m (20-25 ft) static lift
and has a sludge pumping rate in the range of 47.3-78.86 H/s
(750-1250 gpm).
The density gauge for each unit is located below the wet well
discharge point and relatively close to the pump itself. This
arrangement assures a full pipe. Both horizontal and vertical
upflow orientation of the density gauges have provided satis-
factory operation, see Figure 12. However, vertical upflow
orientation is preferred since sand will settle out on the
bottom of a horizontally mounted gauge and falsely indicate a
high density. This has been a problem during wet weather periods
when huge quantities of sand often enter the plant.
The timers and controller for the sludge valves and pump are
mounted just above the density gauge amplifier for each unit
and in the same control panel, see Figure 8. Each unit has a
master timer (0-120 min) which controls the off time of the
pumping sequence. It is this timer which is adjusted to
compensate for diurnal and seasonal variations. In addition,
each unit has four to six (depending on the number of tanks in
the unit) tank timers or delay timers (0-5 min). The primary
purpose of the tank timers is to insure that a new supply of raw
sludge has reached the density measuring unit and that the control
32
-------
ii
TANKS 61-66
10
TANKS 55-60
TRANSFER
STATION
FIGURE 10
LAYOUT OF SEDIMENTATION TANK UNITS
AT THE JWPCP
33
-------
OJ
TRANSFER
STATION
WETWELL
INFLUENT ra&asftaag^S
DENSITY
GAUGE
SLUDGE
PUMP
SLUDGE BLANKET
PRIMARY SEDIMENTATION TANKS
TANK DRAW
OFF VALVE
PRIMARY
EFFLUENT
FIGURE I
SCHEMATIC DIAGRAM OF A SLUDGE PUMPING UNIT
-------
FIGURE 12
VERTICAL (ABOVE) AND HORIZONTAL
(BELOW) INSTALLATION OF DENSITY GAUGES
35
-------
of the pump is not being accomplished by residual sludge in the
suction line. These timers are set for the minimum time required
to accomplish this purpose (normally 1 min.). In case of mal-
function of the density unit however, they can be used to control
the pumping cycle. Red lights located above the recorder for
each unit correspond to the collector pump and each draw off
valve, indicating when the pump is on and when each valve is open.
Sequence of Operation
The following pumping sequence is shown schematically in Figure 13.
When the master timer zeros out, the first tank timer is activated;
this opens the first draw off valve. At the same time, the col-
lector pump is turned on and sludge is pumped out of the first
hopper. If the density of the sludge being pumped is higher than
set point when the first tank timer zeros out, the first valve
will remain open and the hopper will continue to be pumped until
the density drops below set point. At this time, the first valve
will close and the second tank timer will be activated, opening
the second valve. This sequence will continue until all four
(or six) tank hoppers have been pumped, after which the master
timer, which has since reset, will be activated again. If the
density of the sludge being pumped from any tank is below the
set point when its timer zeros out, the valve on that tank will
close and the timer for the next tank in the unit will be acti-
vated. Thus, both over-pumping (except that caused by excessive
tank timer settings) and under-pumping are eliminated because
density is the controlling factor.
Timer changes usually follow a diurnal flow cycle, such as
Figure 1. In the following discussion, only the off timer setting
is changed; the tank timer setting remains constant.
1. 300-900 Hours - The off timer setting is increased during
this period since the accumulation rate is decreasing.
Often, however, the sludge enters the plant partially
digested or septic. As a result, the holding time during
this period must be reduced to prevent gassing. The off
36
-------
TANK
TIMERS
PUMP
START 8
STOP
SET
POINT
DENSITY
CONTROLLER
A
I
l
TO
TRANSFER
STATION
WETWELL
DENSITY
GAUGE
TANK DRAW
OFF VALVE
SLUDGE
PUMP
_J
No. 4
FIGURE 13 SCHEMATIC DIAGRAM OF DENSITY CONTROLLED SLUDGE PUMPING SYSTEM AT JWPCP
-------
timer setting is thus increased but not in direct proportion to
the decrease in accumulation rate.
2. 900-1400 Hours - The off timer setting is gradually
decreased during this period since the accumulation rate is
increasing. However, fresher sludge enters the plant and a
higher sludge blanket level can be maintained without gas-
sing. The off timer setting is thus decreased but not in
direct proportion to the increase in accumulation rate.
3. 1400-300 Hours - The off timer setting is somewhat constant
since the accumulation rate is unchanged.
Adjusting Timer Settings - Density Control
In using density control, only the off timer setting is changed.
The tank timer functions as a delay timer that assures the line
is clear of sludge remaining from the previous cycle or from the
previous tank.
The operator routinely observes the density chart trace and com-
pares it to the set point. Off timer settings are adjusted
according to the following procedure.
1. During the daily period of lowest sludge accumulation, the
off timer is adjusted to a maximum setting which does not
require density control (i.e., the density trace does not
exceed the set point at the end of the one minute pumping
from each tank). This adjustment is necessary at the JWPCP
due to the septic condition of the wastewater during this
low flow period. It is impossible to store the sludge in
the sedimentation tanks long enough to reach the desired
density without gasification occurring. In this case there
is the option of lowering the set point rather than adjust-
ing the off timer; however, this is impractical due to the
inacessibility of the set point adjustment on some units.
2. During the day, the pumping time from each tank should in-
crease in proportion to the increase in accumulation rate.
For example, if the accumulation rate roughly doubles during
a day, then the actual pumping from each tank should roughly
38
-------
double. If the density controlled pumping timer becomes exces-
sive, then the off timer setting should be decreased to increase
the frequency of pumping cycles.
Reading Density Charts
Probably the greatest advantage of density gauges is the contin-
uous recording of the sludge density- The recorder trace tells
the operator the condition of the sludge and any problems or
malfunctions in the pumping system.
The following section discusses the more common recorder traces
and what they mean. Interpreting recorder traces is difficult
since a single trace can have several causes.
1. Gassing Tanks - Figure 14 shows a recorder trace which
indicates under-pumping from the unit tanks (i.e., the
off timer setting is too high). Between noon and 2 p.m.,
the density being pumped is around six percent. However,
after the pump stops the trace immediately drops to
around four percent and remains at this low level until
pumping is again started. This drop indicates separation
of the sludge caused by gassing and settling in the gauge.
Figure 14 shows that the condition improved after the off
timer (OT) setting was decreased from 20 to 10 minutes.
An immediate improvement such as this does not always
occur. Visually observing the tanks and taking corrective
action can usually prevent this problem from developing.
An observation of gas bubbles above the collection sump
is an indicator of trouble and immediate action should be
taken to decrease the setting on the off timer. If only a
portion of the tanks in a unit show gassing, corrective
action dictates temporarily increasing the delay timers
on only the affected tanks. This action causes increased
pumping from these tanks without regard to density. The
delay timers should be returned to their normal setting
after the gassing sludge condition has ceased.
39
-------
FIGURE 1.4
SECTION OF DENSITY CHART SHOWING
GASING TANKS
FIGURE 15
SLUDGE PUMP OFF
SLUDGE PUMP ON
SECTION OF DENSITY CHART SHOWING
WATER LEAK INTO LINE
40
-------
2. Water Leak into Line - The recorder trace in Figure 15
indicates a water leak into the sludge piping. During
pumping the density is observed to be around six percent.
However, after the pump stops the line fills up with water
and the trace drops to zero. The leak is usually caused
by a faulty solenoid valve on the pump packing gland.
3. Vacuum in Line - Figure 16 shows a sudden drop in the chart
trace each time the pump starts. This drop indicates
either a vacuum on the line or a very small water leak.
A vacuum such as this could be caused by a draw-off valve
closing before the pump has shut off.
4. Erratic Charts - An erratic trace such as Figure 17 usually
requires visual inspection of the sludge to determine what
density is being pumped. Several possible causes exist
which include the following: a gross object (such as a
block of wood) stuck in the gauge, sand settling in the
gauge, or an instrument malfunction. If a unit has less
than three tanks in service, an erratic trace which
resembles Figure 15 will occur.
5. Density Control - Figure 18 shows the sludge density
exceeding the overriding set point on every pumping between
2 p.m. and 6 p.m. As previously described, the pumping
continues until the density from each tank drops below
set point.
CALIBRATION AND MAINTENANCE
General
The procedures outlined below are described thoroughly in
manufacturer equipment manuals such as Ohmart or Chicago-Nuclear.
They are presented here to familiarize the reader with the
maintenance requirements of nuclear density gauges.
Calibration Procedures
1. Sampling Technique - Every week one calibration sample is
taken from each density gauge. Two technicians are
41
-------
FIGURE 16
SECTION OF DENSITY CHART SHOWING
VACUUM IN LINE
FIGURE 17
SECTION OF DENSITY CHART SHOWING
ERRATIC READINGS
42
-------
SET POINT @ 6.8 %
FIGURE 18
SECTION OF DENSITY CHART SHOWING
DENSITY CONTROL
SLUDGE PUMP OFF
SLUDGE PUMP ON
FIGURE 20
SECTION OF DENSITY CHART SHOWING
A NORMAL TRACE
43
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are required for the following procedure. After the pump
has started and a steady reading is observed, one technician
records the density while the other technician obtains a
corresponding sample. The samples are delivered to the
laboratory for a total solids determination.
At the JWPCP, calibration samples are taken using the
"encapsulator" device shown in Figure 19. A one-inch sample
line extends from near the density gauge inlet to a nearby
sump. The device itself consists of four valves, one of
which is a three-way valve. To capture a sample, the valves
are first positioned to allow a steady sampling stream to
flow into the sump. Valve no. 1 is closed to stop the sample
flow and then valve no. 2 is closed to capture the sample,
see Figure 19. The captured sample is released into a
container by reversing the position of valve no. 3 and
opening vacuum breaker valve no. 4.
2. Calibration Adjustment - An instrument technician compares
the calibration meter reading to the laboratory analysis of
the sample. A calibration correction is required if the two
values differ by more than one-half percent. To make this
adjustment the process density must again be steady. The
adjustment is made using the CALIBRATION control and can
be done when the meter is reading any value.
3. Water Zero Adjustment - Once a month, the water zero setting
for each density gauge is checked. If a calibration cor-
rection is also required, the water zero check is usually
made at the same time. The check is made by turning off
the collector pump and filling the pipeline with water.
This is accomplished by connecting a nonpotable water hose
to the sample piping. After a steady reading is obtained,
the zero can be ajusted by using the ZERO SUPPRESSION
control.
Time Constant Adjustment
Density control of each tank in a unit will not occur unless the
44
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PUMP DISCHARGE LINE
FIGURE 19
SCHEMATIC OF
SAMPLE ENCAPSULATOR USED AT THE JWPCP
45
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time constant is properly adjusted. The time constant makes it
possible to obtain a balance between the noise band and the
process rate of change (or response time).
The time constant is adjusted to read from water zero to process
in 30-45 seconds. This is approximately the time required to
clear the line of sludge remaining from the previous cycle or
from the previous tank. A minimum tank timer setting of one
minute gives the controller 15-30 seconds to read the density
actually being pumped from each tank.
As described, the response time is first adjusted and then the
resulting noise band checked. Figure 20 shows the acceptable
noise band limit, approximately 0.4 percent total solids. If
the noise band exceeds this amount, it can be reduced by increas-
ing the time constant (i.e., by damping the system).
Maintenance Requirements
1. Daily Checks - This procedure requires approximately ten
minutes per instrument per day- The instrument technician
checks to make sure of the following:
a. Chart is inking properly.
b. Chart time is correct.
c. Chart reading corresponds to meter reading.
d. Timers do not stick.
e. Noise level is not excessive.
f. Trace is not erratic.
2. Calibration Adjustment - This procedure requires approxi-
mately one person-hour per instrument per month.
3. Corrective Maintenance - At the JWPCP corrective mainte-
nance requires approximately one to two person-hours per
instrument per month.
ANAEROBIC DIGESTER OPERATION
General
Efficient and proper anaerobic digester operation requires care-
ful control of process variables. Literature on the subject deals
46
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primarily with heating and mixing. For the most part, little
attention is paid to probably the most important variable of
all, the food supply. Various loading parameters have been
suggested but little has been published regarding methods to
control the loading.
The use of density meters for raw sludge pumping control, coupled
with simple digester feed controls, enables anaerobic digestion
to be performed efficiently. The control system permits loadings
to a series of digesters to be controlled within close limits and
allows the loading to each individual digester to be varied as
the conditions in each tank warrant.
Description of JWPCP Digester System
The JWPCP has a total of 31 anaerobic digesters arranged in two
separate groups; only single-stage digestion is practiced. The
first group contains 27 fixed cover, rectangular digesters, each
with a capacity of approximately 2832 cu m (100,000 cu ft). The
second group is presently composed of four (ultimately 12 or more)
fixed cover, circular tanks, each with a capacity of approximately
14,160 cu m (500,000 cu ft). Despite differences in size, con-
figuration, and location the two groups are identical in operation
and control. Mixing is provided by gas recirculation, temperature
is maintained in the desired range by steam injection, and loadings
are controlled by the system described below.
Basis of Loading Control
Loading parameters are generally stated in terms of weight of
volatile solids per unit volume of digester capacity. Unfortu-
nately, automation of volatile solids determination has not yet
been achieved and laboratory determinations are too time consuming
to be of any use during the charging cycle. However, by using
density control for raw sludge pumping and by incrementally
feeding each digester (5 or 6 times per day), the diurnal
variations in sludge density and volatility are evened out.
Weekly and/or monthly averages of density and volatility,
determined by laboratory analyses of 24-hour raw sludge composites,
47
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provide a satisfactory basis for calculating and controlling
loading by volumetric means as per the following formula:
Volume of raw sludge
= Desired loading (weight of volatile solids per unit volume)
Avg % solids (raw sludge) x Avg % volatile (raw sludge)
x Digester capacity
Control System Elements
The control panel for one group of digesters houses 27 sets of
sludge feed controls, one for each digester in that group. Each
set contains:
1. 24-hour sludge feed timer - The total number of gallons of
sludge to be fed to the digester in one 24-hour period is
set on this timer.
2. Incremental sludge feed timer - The number of gallons of
sludge to be fed to the digester per feeding is set on
this timer. This setting is normally one-fifth or one-
sixth of the volume set on the 24-hour timer depending on
whether the digester is to be fed five or six times during
the 24-hour period.
3. Sludge feed volume totalizer - Displays a running total of
the volume of sludge fed to the digester.
The volume of sludge is measured by a Venturi meter in the raw
sludge line carrying the flow to the digester group. The resul-
tant pressure differential signal from this meter is converted
to a flow signal by an adjacent pneumatic transmitter.
The pneumatic signal is received by a flow recorder in the control
panel, recorded on a circular chart and converted to a pulse-time
signal. This pulse-time signal is received by both the 24-hour
and incremental feed timers. The incremental timer, having been
preset for a specific volume of sludge, is clocked out when that
volume of sludge has passed the flow gauging venturi (the 24-hour
timer is also reduced by this amount).
48
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Sequence of Operation
Pumping to the digestion system is initiated whenever the level
in the raw sludge transfer wet well rises to the level probe and
starts the pumps. The sludge then passes through the delivery
piping and Venturi meter to the first digester in the series.
When the incremental timer clocks out, the feed valve to that
digester closes, the flow signal is transferred to the next
timer in the series, and the feed valve to that digester opens.
Thus, the feed valve to one digester is always in the open
position or is opening while the preceding valve is closing.
The control system cycles through every digester, allowing raw
sludge to be fed to the digesters in the amount so indicated on
their incremental timers. After one complete cycle, the control
system switches back to the beginning of the series, again allow-
ing raw sludge to be fed to the digesters in the amount shown on
their incremental feed timers. However, if in the previous cycle
the amount originally set on the digester total feed counter
(24-hour timer) has been satisfied for any particular digester,
the control system passes over the satisfied digester to the
next digester whose total feed counter has not been satisfied.
If a digester is out of service for cleaning or repair, its
timers are set to zero, and it is bypassed in the feeding sequence
in like manner to a digester whose feeding has been satisfied.
An "on-off" selector switch for each tank accomplishes the same
objective.
The start of the 24-hour control period is purposely selected
to begin late in the afternoon after the laboratory analyses are
completed and the condition of each digester can be evaluated.
Any loading changes to be made are then "dialed in" on the
appropriate timers and the control board is reset by pushing a
single reset button. If only a portion of the tanks have been
fed on the preceding cycle, the ''on-off" selector switches for
those tanks which have been fed are turned to the "off" position
before the reset button is pushed. Thus, the new 24-hour cycle
49
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starts with the tank which would normally be next in line for
feeding. After resetting the control board, the selector switches
are returned to their normal position.
If the feeding of all of the digesters in the group has been
satisfied or if the 24-hour control period expires before manual
resetting occurs, the control system automatically resets all
timers to the positions they were in at the beginning of the
preceding control period. The control system then starts to
cycle through the series again as previously described. Changes
can still be made in the load settings, but it is more difficult
to accomplish than if done before the control board is reset.
Summary
Radioactive density meters have been in operation at the JWPCP
since 1959. They have proven to be an effective tool for con-
trolling the intermittent withdrawal of raw sludge from primary
sedimentation tanks. By controlling the sludge density within
narrow limits, they also permit efficient use of digester capac-
ity and make possible digester loading control by simple volu-
metric means.
50
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SECTION VI
ACTIVATED SLUDGE - PROCESS AIR CONTROL
INTRODUCTION
Since the activated sludge system is an aerobic process, oxygen
must be supplied to sustain metabolism of the microorganisms.
Oxygen requirements vary depending primarily on organic strength
of the primary effluent, the cell residence time at which the
plant is operated, and whether nitrification occurs or not.
Heterotrophic microorganisms in activated sludge use organic
compounds contained in sewage both as a source of energy and
as a source of carbon for cell synthesis. Oxygen demand is
exerted by that portion of organics oxidized to carbon dioxide
and water. An additional oxygen demand is exerted when cellular
organics are consumed for energy, a process termed endogenous
respiration. The extent of endogenous respiration is primarily
dependent upon mean cell residence time (MCRT) in the system,
increasing with longer cell residence times. However, endogenous
respiration is never complete since a fraction of the cellular
organics are resistant to degradation and termed refractory. The
refractory portion normally represents 10 to 20 percent of the
total cell mass. Thus, oxygen consumed may vary from as low as
0.5 Ibs 02/lb COD when endogenous respiration is low to as high
as about 0.90 Ibs 02/lb COD when endogenous respiration is
complete. In normal plant operation, actual oxygen requirements
would fall between these two extremes.
Oxidation of reduced inorganic compounds by autotrophic micro-
organisms can also exert an oxygen demand in the activated sludge
process. Although many reduced inorganics may be present in
sewage, only ammonia nitrogen is significant in terms of an
51
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oxygen demand. Nitrification is a two-step process in which
ammonia is first oxidized to nitrate by the organism Nitrosomonas
Nitrite is then oxidized to nitrate by the organism Nitrobacter.
Step i: NH^ + 3_ 02 *N02~ + 2H+ + H20 (1)
2
Step 2: N02~ + ,1 02 *N03~ (2)
2
Overall: NH^ + 202 ^N03 + 2H+ + H20 (3)
The above reactions furnish energy for the growth of the nitri-
fying bacteria, during which some of the nitrogen is assimilated
into bacterial protoplasm, with carbon dioxide being used as a
source of cell carbon. With an empirical cell formulation of
C5H7O2N, the assimilation reaction can be written as:
5C02 + NH4 + + 2H20 ^C5H702N + 502+ H+ (4)
Overall oxidation of ammonia to nitrate requires 4.57 mg 02
per mg of NH3 -N oxidized. However, some oxygen is produced
during cell synthesis and actual oxygen requirements are somewhat
1 234
less than theoretical. Haug and McCarty, and others, ' '
have shown actual requirements to vary between 3.9 to 4.5 mg 02
per mg NH3 -N. The variation is due to the range of reported
cellular yields for these organisms.
Since nitrification is an aerobic process, the question arises
as to what oxygen tension is required to support the maximum
rate of substrate oxidation. Loveless and Painter, showed that
for a pure culture of Nitrosomonas the rate of ammonium oxidation
was 50 percent of the maximum rate when the oxygen concentration
was 0.3 mg/1 at 20°C. Boon and Ladelout, showed that for
Nitrobacter the rate of nitrite oxidation was 50 percent of
maximum when the oxygen concentration was 0.25 mg/1 at 18°C and
0.50 mg/1 at 32°C.
Garrett, working with activated sludge concluded that nitri-
fication was independent of the oxygen concentration as long as
52
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it was greater than 3 mg/1. This same conclusion was reached
by workers at the Water Pollution Research Laboratory in
8 9
England, . Wuhrmann, studying activated sludge pilot plants,
indicated that a dissolved oxygen concentration of 4 mg/1 was
necessary for rapid nitrification. However, Downing and Hopwood,
and Wild, et all, concluded that nitrification in activated
sludge is not enhanced by oxygen levels greater than 1 mg/1. This
same conclusion has been supported by LACSD evaluations of their
nitrifying activated sludge systems. Therefore, it appears that
the rate of oxidation is largely independent of dissolved oxygen
levels down to concentrations of 1 or 2 mg/1, below which some
rate limitation will be observed.
Nitrification in the activated sludge process tends to be an "all
or nothing" phenomenon. If the mean cell residence time in the
activated sludge process is below the generation time of the
organisms, they will be washed from the system and nitrification
12
will cease. Wuhrmann, reported that a MCRT greater than four
days was necessary to consistently attain a high degree of nitri-
fication. This corresponds with a value of about four or five
days reported by Johnson and Schroepher, . These values are just
greater than minimum generation times reported for the nitrifying
bacteria. At reduced temperatures, generation time is increased
so that a longer MCRT would be required. A design MCRT of ten
14
days for nitrification was recommended by Jenkins and Garrison,
and should give sufficient safeguard for most purposes.
From the above discussion, oxygen requirements to stabilize a
wastewater can be determined within reasonably narrow limits,
depending primarily on influent COD and NH3-N concentrations and
mean cell residence time. However, air quantities required to
satisfy the oxygen demand are more variable, depending on the
type of oxygen transfer equipment used and efficiencies at which
they operate. Also, in all but completely mixed systems, rates
of oxygen consumption will vary along the length of the aeration
tank. Process air control, is therefore, critical to the stable
operation of the activated sludge system. Not only must total
53
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air quantity be controlled, the rate at which it is supplied along
the aeration tank must also be controlled to provide for stable
and efficient treatment.
LACSD FACILITIES
A variety of techniques are used to control process air at acti-
vated sludge plants operated by the LACSD. Techniques used can be
divided into two basic types: (1) use of a control signal to
throttle a centrifugal compressor and, (2) use of preset timers to
control the number of on-line positive displacement compressors.
Cam programmers, dissolved oxygen probes and plant flow rate are
currently used to provide the command signal for the first type
of control listed above. Control methods currently used at each
treatment plant are shown in Table 3.
Preset Timers
Use of preset timers is relatively straight forward and will be
described first. Most treatment plants experience diurnal
variations in both flow rate and sewage strength (as measured
by COD). In general, as flow rate increases so does sewage
strength. This means that process air requirements will vary
diurnally as well. 24-hour timers are used at two of the small
LACSD treatment plants to control operation of a number of par-
allel, positive displacement compressors. Thus, with a knowledge
of the diurnal variation in oxygen demand, timers can be preset
to vary the number of on-line compressors. In this way, oxygen
supply can be approximately matched with oxygen demand.
Diurnal variation in plant flow rate, COD loading, and air supply
to the aeration system at District 26 WRP is shown in Figure 21.
Using data from Figure 21, the pounds of oxygen supplied per
pound of COD were determined and plotted in Figure 22. Resulting
dissolved oxygen concentrations in the aeration system (measured
at the midpoint) are also shown in Figure 22.
One advantage of a timer controlled process air system is that
operation is relatively simple and timers can be easily readjusted
to change the operation. The system is well suited to small
54
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TABLE 3
LACSD ACTIVATED SLUDGE PROCESS AIR CONTROL SYSTEMS
Treatment Plant Air to D.O. Cam
Flow Ratio Probe Programmer Timers
Whittier Narrows WRP X
San Jose Creek WRP X
Pomona WRP X
Los Coyotes WRP X
Long Beach WRP X
District 26 WRP X
District 32 WRP X
55
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en
cr\
o
.p
o
QrO
O
o
1 I I I I I I I I I I f
I I I
AIR SUPPLY
I I I I I I I I I I I I
0_
0»
E
UJ
oU_
10 '
Q _
O
8 -
go
<0 -J
o:
§<
I2M 0100 0200 0300 0400 0500 0600 0700 0800 0900 1000 1100 I20O 1300 1400 1500 1600 1700 1800 0
HOUR OF THE DAY-AUGUST 15,1974
FIGURE 21
ACTIVATED SLUDGE OPERATIONAL PARAMETERS
DISTRICT 26 WATER RENOVATION PLANT
-------
I
I I I
i ribs 02/lbCOD
DISSOLVED OXYGEN
CONCENTRATION
I I I I I I I I
II
I2M 0100 0200 0300 0400 0500 0600 0700 0800 0900 IOOO 1100 1200 1300 1400 1500 1600 1700 1800
HOUR OF THE DAY, 8-15-74
FIGURE 22
ACTIVATED SLUDGE OPERATION PARAMETERS
DISTRICT 26 WATER RENOVATION PLANT
-------
treatment plants where total air requirements are not large.
However, preset timer control has some disadvantages which,
in general, preclude use in larger treatment plants. Oxygen
demand curves can not be exactly matched since oxygen supply can
only be incrementally changed. This is evident in Figure 22 where
a sudden increase in mixed liquor DO accompanied start-up of the
second air compressor. In addition, diurnal patterns of oxygen
demand are subject to daily, weekly, and seasonal variations.
It is difficult to continually readjust timer settings in antici-
pation of such changes. As a result, it is likely that most
treatment plants would supply an excess of air to compensate for
fluctuations in the pattern of diurnal variation.
In summary, timer control of parallel compressors provides an
adequate process air control system in small treatment plants
where design simplicity is important and excess air can be
supplied without significant economic loss.
Cam Programmers
Five of the LACSD activated sludge plants have the flexibility
of controlling process air flow by means of cam programmers. A
schematic diagram illustrating this mode of operation is shown in
Figure 23. A converter transmits a control set point signal which
is proportional to the position of a cam follower on the edge of
a rotating cam. The transmitted signal is a DC current signal.
The cam is driven electrically and completes one revolution in
24 hours.
The converter applies its signal to a ratio controller which changes
the set point of the controlling system by a preset adjustable ratio.
The controlled variable signal is then transmitted to the air flow
controller which compares an input signal (air flow rate) to the
set point signal from the ratio controller. The air flow rate
signal is generated by a flow tube and differential pressure
transmitter. Since the resultant signal is proportional to the
square of the air flow rate, a square root extractor is used to
produce a signal directly proportional to flow rate. Ratio set
58
-------
rruwiroTirci 4-20 ma k RATIO R/i
CONVERTER *
PAM FOI 1 nWFR - ••• ••-
f 0 J J SQUARE ROOT
\^ J EXTRACTOR AIR F
CAM (Irod) T
DIFF, PRESSURE
TRANSMITTER
^ 1 J — n
PROCESS AIR <
fTIO SET POINT ^ AIR FLOW
CONTROLLER
4-20 ma
LOWRATE SIGNAL o
8
|
3
1 .^> [
/ V.
^ ^ ^°yi£
TUBE AIR /^-^\ INL.
rnMDDCccno A \ >
J «— '" SIGNAL
J <
-^ i
/ANES
FIGURE 23 SCHEMATIC DIAGRAM OF PROCESS AIR CONTROL USING A CAM PROGRAMMER
-------
point and air flow rate signals are compared in the air flow
controller which transmits an output signal to control posi-
tioning of compressor inlet guide vanes.
Knowing daily variations in flow rate and sewage stength, as
measured by COD and NH3-N concentrations (if nitrification is
desired) the diurnal variation in oxygen demand can be determined.
A cam can then be cut to regulate oxygen supply to meet the
expected oxygen demand. Should supply not exactly balance
demand, a new cam is cut until, by trial and error, supply
balances demand. Cam programmers offer an additional advantage
over preset timers (described previously) in that compressor
operation can vary anywhere from 0 to 100 percent of maximum
output.
A modification of cam programmer control is used at the Whittier
Narrows WRP. At this plant, it is possible to take as much or
as little flow as is desired from the trunk sewer passing the
plant. Air flow to the aeration tanks is maintained at a
constant rate. To keep oxygen supply and demand in balance, plant
influent flow rate is varied by a cam programmer to compensate for
changes in sewage strength. The ratio of peak daily to minimum
daily flow is about 1.5 under this mode of operation.
While performance of the cam programmer system has, in general,
been satisfactory certain disadvantages are inherent in its oper-
ation. Daily, weekly, and seasonal fluctuations in diurnal
oxygen demand require periodic cam readjustment. Shock loads,
either in flow or sewage strength, may upset plant performance
since they can not be anticipated when the cams are originally
cut. Experience has also indicated that it is difficult to main-
tain an exact dissolved oxygen content in the aeration tank. For
example, if it is desired to maintain 0.5 mg/1 at a certain point
in the aeration tank, the sensitivity of a cam may not be suffi-
cient to assure that DO at all times.
Air to Flow Ratio
Under this mode of operation process air is automatically
60
-------
maintained at a preset (adjustable) ratio to plant flow. An
electrical signal, proportional to flow rate, is generated by
the plant influent flow meter and used to regulate the quantity
of process air. Actual ratio of process air to plant flow rate
3
is adjustable over the range from 0 to 5 ft /gallon. A schematic
diagram of this control system is shown in Figure 24.
This process air control system has operated satisfactorily at
both the Pomona and Los Coyotes WRP's. An advantage over cam
programmer control is offered since changes in diurnal flow rate
patterns are automatically sensed and compensated for. Hence,
once the desired air'to flow ratio is selected, operation is
generally automatic. The system will even respond to shock loads
resulting from increased flow rate. However, the system will not
respond to sudden increases in waste organic strength. This
disadvantage may be significant in treatment systems which receive
a large proportion of industrial wastes. Another disadvantage
lies in the fact that peak flow periods are normally associated
with periods of peak organic strength. Thus, if the air/flow ratio
is sufficient to maintain adequate DO during the peak flow period,
the ratio may be too high during the low flow period when waste
organic strength is less. This is partially offset however, as
during the lower flow period when waste strength is less, the
amount of oxygen consumed by endogenous respiration represents a
greater percentage of the total oxygen consumed than it does during
peak load periods. Simply stated, if the organic strength had no
diurnal variations, a higher air/water ratio would be required
during the lower flow periods than during the higher flow periods.
DO Probe Control
Control of process air by dissolved oxygen probes located in the
activated sludge tanks is the normal mode of operation at the San
Jose Creek and Long Beach Water Renovation Plants. A schematic
diagram of the system is shown in Figure 25. In principle,
dissolved oxygen probes provide a feedback signal to control
operation of the air compressors. This provides a system which
61
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NJ
MAGNETIC
FLOWMETER
> MANUAL SET
POINT
1
1 4-20 mn^ RATIO RAT
FLOW TO
CURRENT
CONVERTER
RECORDER
1 " STATION
SQIIARF Rnnr '
^_ EXTRACTOR AIR FL(
r T
DIFF PRESSURE
TRANSMITTER
^1 i
PROCESS AIR < 11
\J I — — — «-•
FLOW
TUBE
rt
10 SET POINT ^ AIR FLOW
CONTROLLER
^20 ma i
)WRATE SIGNAL g
z
o
o
a.
o
T
r-1— ^ L
/ \ ^
v UN — ^
AIR X_X INh
^MPRFQQHP 4 \
1VN9IS u-i I
^ \
ET GUIDE
YANES
FIGURE 24
SCHEMATIC DIAGRAM OF PROCESS AIR CONTROL USING AIR FLOW RATIO
-------
D 0
SENSOR IN
AERATOR
D 0
INDICATOR
TRANSMITTER
V/l
CONVERTER
RECORDER
PROCESS AIR
SET POINT
(DO mg/l)
OXYGEN
CONTROLLER
SQUARE ROOT
EXTRACTOR
T
DIFF PRESSURE
TRANSMITTER
1
1 r— r
^ RATIO ^ AIR FLOW
STATION " CONTROLLER
j k
i
o
OC
0
o
h-
Q.
|
_^s L
[I I / ^ J
J L- L
FLOW
TUBE
1 "-^ SIGNAL
1 ( K ^
AIR X^X INLETGUIDE
rnMPRFQQOR / \ VANES
FIGURE 25
SCHEMATIC DIAGRAM OF PROCESS AIR CONTROL USING DO SENSOR PROBES
-------
can respond to any diurnal fluctuation in oxygen demand as well
as shock loads whether they be in terms of flowrate or waste
strength.
Primary elements for measuring dissolved oxygen are DO probes
located in the aeration tanks. Optimum number of probes depends
on the type of activated sludge process used. For a completely-
mixed aeration tank only one DO sensor would be needed since DO
concentrations would be uniform throughout the tank. The San Jose
Creek and Long Beach WRP's, which normally use DO sensors for
process air control, have nearly plug flow activated sludge systems
which employ step feeding (step aeration) of the waste. Hence, DO
concentrations vary continuously along the length of the aeration
tank as shown in Figure 26. This necessitates use of a number of
DO sensors placed strategically along the aeration tanks.
The probes transmit signals proportional to the dissolved oxygen
concentration to dissolved oxygen indicating transmitters (refer
to Figure 25). The electrical signals are then transmitted to a
control panel where they are recorded. One signal is automati-
cally or manually selected to be used as a primary input command
signal to the dissolved oxygen controller. Desired DO concen-
tration to be maintained at the controlling probe can be manually
set at the oxygen controller. The ratio station receives the
output signal from the oxygen controller and applies a ratio set
point signal to the air flow controller. This in turn provides
an output signal used to control the position of inlet guide vanes
on each process air compressor. A signal limiting device is
provided in the controller to prevent closure of inlet guide vanes
beyond the point that would cause compressor surge.
The reason for controlling process air to the activated sludge
system is the necessity of balancing oxygen supply with oxygen
demand. Beyond that DO levels should be sufficient to assure
that reaction rates are not DO limited. The most straightforward
method of accomplishing these objectives is to simply monitor the
DO level in the aerator and use that as a feedback signal to
64
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O»
E
CE
UJ 9
O ^
Z
O
O
g
Ss
3
O
CO
CO
1 I I r
TANK I
1 I I F
TANK 2
Jill
FEED POINTS
CONTROLLING DO PROBE
SET POINT AT 1.0 mg/l
1 r~i r
TANK 3
I i
1 I I I
TANK 4
CONTROLLING
DO
PROBE
I I I I I I I I I I I I I I I I I I I
0 45' 90' 135' 180' 225' 270* 315' 360' 405' 450' 495' 540' 585' 630' 675' 720' 765' 810' 855' 900'
DISTANCE ALONG AERATION TANK
AERATION TANK DO PROFILE AT LONG BEACH WATER RENOVATION PLANT
FIGURE 26 7-1-74 - 1230-1430 hours
-------
control compressor operation. Response to changes in diurnal
flow pattern as well as to shock loads of either flow rate or
waste strength are advantages of this type of system. Experi-
ence with DO probe control systems, however, has revealed several
operational characteristics which will be noted.
As previously discussed, DO levels below 1 or 2 mg/1 will affect
nitrification kinetics by imposing a rate limitation. If the
MCRT is above 5 or 6 days and the DO set point below about
0.5 mg/1, nitrification may not occur because of the DO rate
limitation. However, if the DO set point is increased much above
0.5 mg/1, the rate limitation is removed and nitrification will
proceed. This will produce a sharp increase in oxygen demand and
process air flow will increase dramatically to try and match
the demand. If the operator is not aware of this phenomenon,
he may spend many anxious moments pondering the sudden increase
in process air flow. If nitrification is not desired, the best
operational procedure is to keep the MCRT below about four days.
However, this may not produce the best quality effluent in terms
of suspended solids. The only other recourse is to maintain DO
concentration in the aeration tanks less than 0.5 mg/1 which
limits flexibility of the process air flow system.
In the DO probe system currently used, only one DO probe can be
selected at any time to control process air flow. Experience
with the system should indicate the position of the controlling
probe that produces the best overall effluent quality. In LACSD
experience, the controlling DO probe has usually been located
near the midpoint of the aeration tank. A dissolved oxygen pro-
file along the length of the aerator at the LBWRP is shown in
Figure 26. The activated sludge system is divided into four
tanks arranged in series. Return activated sludge enters at the
head end of tank 1 while primary effluent is step fed into the
first three tanks as shown in Figure 26. The controlling DO
probe was located between the last two inlet gates with the
control set to maintain 1.0 mg/1. This DO concentration was
maintained at the location of the control probe but varied at
66
-------
other locations in the aeration tank. In general, DO levels
decreased at each feed port and increased significantly in Tank 4
which contained no feed ports. If the controlling probe had been
located in Tank 4, the same pattern of air supply may have resulted
in excessively low DO levels in the first two tanks.
Theoretically, there would be some advantage to locating the DO
probe near the beginning of the aeration system in that response
to shock loads would not be as delayed. However, experience has
indicated that compressor operation is more uniform if the con-
trolling probe is located in the latter half of the aeration
system. Flexibility in probe location is recommended in any
design. In a more recent LACSD design, each four-pass aeration
system has eight possible locations for mounting DO probes, one
at each end of each pass. Any four of these locations can be
used at one time, with the control system automatically choosing
for control, the sensor which is producing the lowest reading.
Flexibility also allows any single probe location to be used as
the control point.
It should be noted that the DO control system does not regulate
the pattern of air flow along the aeration tank. It only regulates
total air flow to the aeration tank in order to maintain a set
point dissolved oxygen concentration at the site of the controlling
probe. The operator must still adjust air flow patterns to assure
adequate DO at all points in the aeration tanks. For the DO profile
shown in Figure 26, approximately 60 percent of total air flow was
supplied to the first two tanks with the remaining 40 percent sup-
plied to the latter two tanks.
Plant flow rate, process air flow rate, and dissolved oxygen con-
centration at the controlling oxygen probe are plotted in Figure 27
from data collected at the Long Beach WRP. Dissolved oxygen con-
centrations are seen to oscillate around the set point value of
3 rag/1 with amplitude averaging about +0.5 mg/1. Rather large
excursions in DO concentration were noted when the compressors were
placed on manual control. Upon returning to DO probe control,
67
-------
PROCESS AIR FLOW PLANT FLOWRATE, D 0
IQ3SCFM MGD mg/l
_ _ ro ro _ _
oiooiOoi ro •& o> o> o ro A —ro'w^oi
. X, /\ X
• ^
" — ^^
'\XV>
lA /"^J
i/u
-^^
""••N
— \s^
DO SET
A n /\
J V p — '
^
| "S^
^v
V^_
~ nr
i
^ — >.
" x
f\
-AH
\j
\
x
^s
- ' -***~
-+
^
\.
\,
VJ
•
^^
^
\
COMPRESSO;
*[ M
^
\tn n
ANUALl
J
/ —
f
s
/
/
Y
f
V^->v
^, — ~~
S
^-=
•DO PROBE CONTROL
^
rf
1
^^-^
-'
CTi
00
0100 0200
0300 0400
0500
0600
0700 0800
090O
1000
1 100
1200
FIGURE 27
CONTINUOUS CHART RECORDINGS OF DO AT CONTROLLING PROBE, PLANT FLOWRATE,
AND PROCESS AIR FLOW AT LONG BEACH WATER RENOVATION PLANT- 9-22-74
-------
however, oxygen concentrations returned to the set point value.
Oscillation of the DO concentration about the set point value as
shown in Figure 27 is characteristic of control systems employing
proportional band with reset and rate control. The proportional
function of the controller provides a signal proportional to
difference between the controlled variable (in this case, the DO
concentration) and the set point value. Reset action (also known
as integral action) produces a corrective signal proportional to
the length of time the dissolved oxygen has been away from the
set point. Rate action (also known as derivative action) produces
a corrective signal proportional to the rate at which the con-
trolled variable changes from set point.
All of the above control functions are adjustable. With regard to
proportional action, for example, the amount of deviation of the
DO concentration from set point required to move the air compres-
sors through their full operating range is known as the "propor-
tional band" and is adjustable within the controller. This means
that each controller must be tuned to the system it is control-
ling to obtain the proper combination of proportional, reset and
rate actions.
Another operational consideration with regard to a DO probe
control system is that more routine maintenance is required than
with other control techniques previously described. Most addi-
tional work centers around maintaining and checking probe cali-
brations, replacing probe membranes and performing instrumental
adjustments. Plant operators, using a portable DO sensor, measure
dissolved oxygen concentrations along the aeration tank on a
daily basis. If the DO profile is abnormal in any way, the
operator may decide to have the controlling probe examined.
Instrument maintenance personnel perform in situ calibrations of
the DO probes (again using a portable DO meter) on approximately
a weekly basis. Membranes are replaced when probe operation
becomes erratic or the probe can no longer be calibrated. Exam-
ination of log records indicates that instrument personnel
performed routine maintenance, adjustments, and calibrations on
roughly a weekly basis.
69
-------
SUMMARY
All of the process air control systems described above offer
advantages and disadvantages some of which are described in
Table 4. As sophistication increases, so does the accuracy with
which oxygen supply and demand can be balanced. But as sophis-
tication increases, so also system costs and maintenance require-
ments increase. All of these factors must be weighed in assessing
the correct design for a given treatment plant. In general, as
plant size increases, the benefit/cost ratio of sophisticated
instrumentation increases. In addition, many treatment plants
are faced with meeting increasingly stringent effluent standards.
Under these conditions, the expense of process control instrumen-
tation may be justified provided it offers the promise of better
effluent quality.
Latest LACSD designs have incorporated a number of process air
control systems to provide a wide range of flexibility in plant
operation. For example, the Long Beach Water Renovation Plant
has instrumentation for controlling process air by cam programmers,
air to flow ratio, and DO probes. In addition, primary effluent
turbidity can be used to control process air but this system has
never been used. A schematic instrument flow diagram showing the
interrelationship of process air control systems at the Long
Beach WRP is shown in Figure 28.
70
-------
TABLE 4
SUMMARY OF RESPONSE OF PROCESS AIR
CONTROL SYSTEMS TO OPERATIONAL VARIABLES
Variable
Process Air Control Systems
Preset Cam Air/Flow DO
Timers Programmers Ratio Sensor
Response to predictable
patterns of flow rate
and organic strength Yes Yes
Response to shock
loading in flow rate No No
Response to shock load-
ing in organic strength No No
Ability to balance
oxygen supply with
demand Adequate Good
Sudden increase in
air supply if
nitrification
becomes established No No
Maintenance
requirements Minimal Some
Yes
Yes
No
Good
Yes
Yes
Yes
Best
No
Yes
Some Significant
71
-------
[0
PANEL I
A
DIVIDER
C
o i
RECORDER
0-5
RATIO
UNITS
PANEL
2
FLOW
RECORDER
F
TO OTHER COMPRESSOR A!R
INLET GUIDE VANES COMPRESSOR
FIGURE 29
SCHEMATIC INSTRUMENT FLOW DIAGRAM
-------
SECTION VI
REFERENCES
1. Haug, R.T., and McCarty, P.L., "Nitrification with Submerged
Filters", J. Water Pollution Control Federation, Vol. 44,
No, 11, (1972)
2. Lees, H., "The Biochemistry of the Nitrifying Organisms:
1. The Ammonia-Oxidizing System of Nitrosomonas."
Biochem. J. , 52, 134-139, (1952)
3. Wezernak, C.T., Gannon, J.J., "Oxygen-Nitrogen Relationships
in Autotrophic Nitrification." Applied Microbiology, 51,5,
1211, (1967)
4. Downing, L.L., Knowles, G., "Nitrification in Treatment Plants
and Natural Waters: Some Implications of Theoretical Models."
5th Internation Water Pollution Research Conference, July-Aug.,
(1970)
5. Loveless, J.E., Painter, H.A., "The Influence of Metal Ion
Concentrations and pH Value on the Growth of a Nitrosomonas
Strain Isolated from Activated Sludge." J. Gen. Microbiol.,
52, 1-14, (1968)
6. Boon, B., Ladelout, H., "Kinetics of Nitrite Oxidation by
Nitrobacter Winogradskyi." Biochemical Journal, 85, 440-447,
(1962)
7. Garrett, M.T., "Significance of Growth Rate in the Control
and Operation of Bio-oxidation Treatment Plants." Ind. Water
and Waste Conf., Rice University, Houston, Texas, (1961)
8. Water Pollution Research Laboratory, "Effect of Dissolved
Oxygen on Nitrification," Ministry of Technology, Her
Majesty's Stationary Office, London, (1964)
9. Wuhrmann, K., Advances in Biological Waste Treatment, Edited
by W.W. Eckenfelder and J. McCabe, Pergamon Press, London, (1963)
10. Downing, A.L., Hopwood, A.P., "Some Observations on the
Kinetics of Nitrifying Activated-Sludge Plants." Schweiz,
A. Hydrol., 26, 271, (1964)
73
-------
11. Wild, H.E., Sawyer, C.N., McMahon, T.C., "Factors Affecting
Nitrification Kinetics." J. Water Poll. Cont. Fed., 43, 9,
(1971)
12. Wuhrmann, K., "Objectives, Technology, and Results of
Nitrogen and Phosphorus Removal Processes, "Advances in
Water Quality Improvement, 143, Eds. E.F. Gloyna and
W.W. Eckenfelder, University of Texas Press, Austin, (1968)
13. Johnson, W.K. and Schroepfer, G.J., "Nitrogen Removal by
Nitrification and Denitrification," J. Water Poll. Cont.
Fed., 36, 1015, (1964)
14. Jenkins, D., Garrison, W.E., "Control of Activated Sludge
by Mean Cell Residence Time." J. Water Poll. Cont. Fed.,
40, 1905, (1968)
74
-------
SECTION VII
RETURN ACTIVATED SLUDGE - FLOW CONTROL
INTRODUCTION
Mechanisms to control sludge blanket levels in secondary clarifiers
have been incorporated in LACSD treatment plant designs since about
1960. Many early designs were unsuccessful and rather unsophis-
ticated compared to today's control technology. Nevertheless,
these early attempts at sludge blanket level control led to more
effective control techniques incorporated in current designs. It
also provided District's personnel with considerable experience
in evaluating various control techniques.
Control of sludge blanket level in the final clarifier is desir-
able for several reasons. If return flow is too great, sludge
hoppers will be emptied of sludge particularly during low flow
periods when solids loading on the clarifier is low. This results
in a low concentration of return sludge. Power requirements are
increased as return pumps must convey a greater volume of thin
sludge. If anaerobic digestion is used to treat waste activated
sludge, excessive digester capacity is used in treating the thin
sludge. On the other hand, if return sludge flow rate is too low,
sludge blanket levels could conceivably rise to the level of the
effluent weirs. This would be somewhat extreme, however, and should
never occur with good plant operation.
Maintaining a constant sludge blanket level offers some additional
advantages to plants that are hydraulically overloaded. Detention
times are determined by total flow through a clarifier, total flow
being the sum of plant flow and return sludge flow. Thus, main-
taining a more concentrated return sludge minimizes the hydraulic
loading on the final clarifiers. Another advantage is that the
detention time per pass through the activated sludge system is
increased.
75
-------
Another mode of return sludge control is to return a constant
flow rate from the clarifier to the activated sludge unit.
Solids are stored in the clarifier hoppers during high flow
periods. This control scheme offers several advantages in that
operation is straightforward and virtually no control equipment
is required, Return sludge is relatively thin during low flow
periods however, and this may be. undesirable if the treatment
plant and/or digesters are overloaded. LACSD upstream treatment
plants discharge waste sludges back to the sewer for subsequent
treatment at the main treatment facility. Thus, obtaining the
thickest possible waste sludge is not a normal operating consid-
eration. Maintaining a constant return rate has proven to be an
adequate control technique under these conditions. However, as
plant flow rates increase, the incentive to reduce recycle flow
rates also increases. This prompted the following study on
return sludge flow control techniques.
The Long Beach Water Renovation Plant was the site of a two-month
study designed to obtain operational data on the return sludge flow
control system. This particular system incorporated latest LACSD
thinking with regard to sludge blanket level control. The plant
contains six final clarifiers, one of which was used in documenting
the return sludge control system. The remaining clarifiers were
operated with a constant return rate.
System Description
A schematic diagram of the return sludge control system and
associated experimental apparatus is shown in Figure 29. Heart
of the system consists of two sludge detector probes installed
in the final clarifier above the return sludge hoppers. Probes
were model #8100 automatic sludge level detectors manufactured
by the Keene Corporation. Each probe contains an infra-red diode
light source and a photocell sensor separated by an open gap of
approximately two inches. When installed in the final clarifier,
the photocell is illuminated by the infra-red diode. Photocell
resistance is governed by the amount of light received from the
76
-------
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DJ
m
73
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r
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V W.S.
CLARIFIER
KEENE
PROBE
No. 2
KEENE
PROBE
No. I
TURB.
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i
tOBE ACT.
VALVE
IS. REC.
g
VALVE
POS.
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MEDIAN SET POINT
{%VALVE OPEN
WITH PROBE No. I
ACTIVATED)
MINIMUM SET POINT
"(% VALVE OPEN
T WITH NO PROBES
, ACTIVATED)
I
W.S.y
TO DRAIN
RETURN SLUDGE
WET WELL
WATER SURFACE
ELEVATION HELD
CONSTANT BY
PROPORTIONAL
BAND WITH RESET
CONTROLLER
C
CO
rn
TJ
SCHEMATIC DIAGRAM OF RETURN SLUDGE CONTROL SYSTEM
FIGURE 29 AND ASSOCIATED EXPERIMENTAL APPARATUS USED IN STUDY
-------
infra-red diode. Thus, a sludge blanket at the probe will de-
crease light transmission and the resulting increase in photocell
resistance is used as a control signal to regulate the return
sludge flow rate.
The controller contains sensitivity adjustments, relays, timing
devices, and circuitry necessary to regulate operation of the flow
control valve. If a probe senses a sludge blanket, the timer is
started which in turn activates the control valves. The valve re-
mains activated until the timer reaches the end of its preset in-
terval. At this point, the valve will remain activated as long as
the detector probe continues to sense a sludge blanket. When
sludge is no longer sensed, the valve will deactivate. Purpose of
the timer circuit is to prevent frequent on-off operation of the
valve which would cause undue wear of the mechanical components.
Valve position is determined by a current trip controller with two
adjustable set points. One set point controls minimum valve
position with no probes activated. The other set point determines
median valve position when probe no. 1 (lower probe) is activated.
Should probe no. 2 activate, the control valve is positioned to
full open.
Under normal conditions, the sludge blanket will be located below
the lower Keene probe. During the low flow period, the draw off
valve will be at its preset minimum opening. As flow rate in-
creases, solids loading on the clarifier increases and the sludge
blanket level rises. As the sludge blanket reaches the lower probe
the draw off valve should open to the preset median position.
Return flow rate should then be sufficient to lower the blanket
level or at least maintain a constant elevation. If, after the
preset timer interval, sludge level has dropped below the sensor,
the valve will return to minimum open position. If sludge level
has not dropped by the end of the interval, the valve will remain
at the median open position until sludge level has dropped.
During normal plant operation, sludge blanket levels should never
reach probe no. 2 (higher probe). Should the upper sensor be
78
-------
activated, however, draw off valve position will increase to
full open. Valve position will remain as such until the preset
timer interval expires after which the draw off valve will
return to median position as soon as the sludge level falls
below probe no. 2.
Several pieces of experimental apparatus were assembled for this
study which are not part of the normal control system, These
included a two-pen recorder for recording probe actuation and
subsequent valve position, a Hach falling stream turbidimeter
to measure light transmission, and a light transmission recorder.
Samples for the turbidimeter could be obtained from any level in
the water column of the clarifier.
Relationship between Plant Operating Parameters and
Return Flow Rate
Proper valve settings for controlling sludge blanket level depend
upon plant operating parameters and settling characteristics of
the activated sludge. A schematic diagram of flow distribution
in the secondary portion of an activated sludge treatment plant
is shown in Figure 30. Performing a mass balance about the
secondary clarifier gives the following:
(Q± + Qr>X± = QeXe + (Qr + Qw)Xr (1)
Where Q. = primary effluent flow rate
Q = secondary effluent flow rate
Q = return sludge flow rate
Q = waste sludge flow rate
w
X. = aerator effluent MLSS concentration
i
X = secondary effluent suspended solids
concentration
X - return sludge suspended solids concentration
If effluent suspended solids concentrations are within the nor-
mally observed range of 5 to 25 mg/1, the mass rate of solids
79
-------
Qi
CO
o
AERATOR
Qi+Qr,Xi
SETTLER
Qe,Xe
Qr,Xr
|Qr+Qw,Xr
4 Qw,Xr.
FIGURE 30 FLOW DISTRIBUTION AND SOLIDS BALANCE IN ACTIVATED SLUDGE PROCESS
-------
lost in the effluent can be neglected and equation 1 becomes
(Q± - Qr)X± = (Qr + Qw)Xr (2)
In normal operation of the activated sludge process waste flow
rate, Q^ is usually less than 10 percent of the return flow
rate, Q^. Neglecting this term equation 2 becomes
(Q± + Qr)x± = Qrxr (3)
Rearranging terms
Qr = ?A (4)
r x -x.
r i
Concentration of return sludge, X , is partly a function of
return rate, Q . As the return rate decreases sludge depth in
the final clarifier would increase which should result in a
slightly thicker sludge. Magnitude of this effect would be a
function of sludge settling characteristics and the particular
sedimentation tank design. Q., X., and X can be measured and
the values used in equation 4 to predict a return flow rate.
Should operation at the predicted return rate result in changes
in X and X. , the new values can be used in equation 4 to predict
a new return rate and so on.
Another approach to predicting the return sludge concentration
involves the settling characteristics of the MLSS as measured
by the SVI test. This latter test is performed at least daily
in most activated sludge plants. As such, it is a convenient
source of information on the settling characteristics of the
activated sludge.
Average concentration of solids in the one liter graduate used
for the SVI test can be determined as
6
Sludge concentration in mg/1 = 10 /SVI (5)
If it assumed that this same concentration can be obtained in
the return flow from the secondary clarifier, equation 4 becomes
Q - Qixi (6)
106 - X.
svi -1
81
-------
Whether equation 5 accurately predicts the return sludge
concentration will, again, depend on efficiency of the sec-
ondary clarifier.
Diurnal variations in plant flow rate and MLSS concentrations
must be taken into account when using equations 4 or 6. During
the low flow period, the minimum return rate should be sufficient
so that the Keene probes rarely, if ever, will actuate. Thus,
the proper minimum return rate Qr min (both probes deactivated)
can be estimated by using minimum flow conditions in either
equation 4 or 6.
During peak flow periods, the return sludge rate should be
sufficient to maintain a constant sludge blanket level with the
lower Keene probe actuated. Thus, the median return rate Q -,
(lower probe actuated) can be estimated by applying peak flow
conditions to equations 4 or 6.
RESULTS
Return sludge flow control equipment described above was operated
at the Long Beach WRP for a two-month period from July to
September, 1974. The study was designed to answer the following
questions: (1) could the control equipment described above
maintain a constant sludge blanket level, (2) what operating
parameters affected performance of the control equipment,
(3) could equations 4 and 6 be used to estimate proper return
sludge flow rates, and (4) how much operator time would be needed
to maintain the control equipment.
SVI data collected over the period of the study is shown in
Figure 31. Each data point represents the average of two daily
SVI tests, one conducted in the morning and the other in the
afternoon. The plant suffered from severe bulking three times
during the study period. In all cases, the bulking was caused
by filamentous organisms. Rising sludge also occurred during
two weeks of the study period. The plant was being operated to
achieve full nitrification and the rising sludge was caused by
subsequent denitrification in the final clarifiers. Rising sludge
82
-------
800
oo
OJ
Mill
I I I II
RISING SLUDGE
IN FINALS
I I I I I I I I I I I I I I I I I I I I
I I I I I I I I
7-11 13 15 17 19 21 23 25 27 29 51 8-24 6 8 10 12 14 16 18 20 22 24 26 28 30 9-1 3 5 7 9 II
DAY OF THE MONTH
DAILY SVI DATA ON AERATION TANK DURING STUDY PERIOD
FIGURE 31
-------
was observed in all secondary clarifiers and was not caused by
the return sludge control equipment. These problems disrupted
normal plant operation but did allow the control equipment to
be operated with sludges of varying settling characteristics.
Sampling Techniques
One of the study objectives was to determine whether a constant
sludge blanket level could be maintained with the control equip-
ment. Therefore, some method was needed to determine the sludge
blanket location in the final clarifier. The first attempt made
use of a Kemmerer sampler which could be lowered to a desired
depth and then tripped by a messenger. Samples could be collected
at increasing depths until the sludge blanket was detected. Two
problems arose with this system. First, the Kemmerer sampler
caused considerable disturbance in the water column. After the
first sample had been collected, there was no assurance that
subsequent samples represented the true condition of the water
column. Second, the sampler itself was approximately two feet
in length and the location of the sludge blanket could not be
placed to any greater degree of accuracy. Since the elevation
difference between probes no. 1 and 2 was usually two feet, the
level of accuracy was not sufficient.
To effect greater accuracy in locating the sludge blanket, a
plexiglas tube, one-inch in inside diameter and 16 feet long,
was constructed. During sampling, the tube was gently lowered
into the water column until the top of the tube was flush with
the water surface. The tube was then capped with a stopper and
withdrawn. This sampling procedure allowed the entire water
column to be visually inspected at one time and also increased
accuracy in locating the sludge blanket.
When the SVI was less than about 150, a well-defined sludge-liquid
interface existed and sludge blanket levels could be visually
determined to within about one foot. However, when the SVI
increased much above 300, a definite interface no longer existed
in the final clarifier. Instead, a gradual increase in suspended
84
-------
solids was observed at all depths below the water surface. This
situation is graphically illustrated in Figures 32 and 33 where
suspended solids concentration and light transmission are plotted
as a function of depth in the final clarifier. Samples were
collected using the Kemmerer sampler and percent transmission was
determined with a spectrophotometer at 600 my wavelength, 1 cm
lightpath. For the data in Figure 32, the SVI was 224 and,
using the plexiglas tube, the sludge interface could be visually
determined to within two or three feet. Subsequent tests with
SVI' s near 100 indicated that the sludge interface could be placed
to within about one foot of depth. When bulking occurred, however,
it was difficult to visually locate the sludge blanket level as
indicated by the data presented in Figure 33.
To effect greater accuracy in locating the sludge blanket interface
and to avoid the subjective assessments necessary in using the
plexiglas sight tube, the monitoring equipment illustrated in
Figure 20 was assembled. Components of the monitoring system
included an intake manifold, sampling pump, Hach Falling Stream
Turbidimeter and a recorder. The intake manifold was a multiple
port device designed to minimize approach velocities and avoid
pulling up sludge from lower depths. The manifold could be located
at any depth in the water column. The Hach Falling Stream
Turbidimeter is designed for measuring high turbidities and is
commonly used for locating sludge blanket levels. The amount of
light transmitted through a sample is measured (as opposed to
measuring scattered light) which is similar to the action of the
Keene probe.
Light transmission measured by the turbidimeter was correlated
with suspended solids concentration in the sludge with the results
shown in Figure 34. This correlation applies only to sludge
encountered during this study and should not be applied to other
types of sludge. Nevertheless, it provides a useful means of
estimating suspended solids concentrations from light transmission
data.
85
-------
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LJ 13
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15
16
17
18
PERCENT LIGHT TRANSMISSION
20 30 40 50 60 70 80
90
100
I I I
PERCENT TRANSMISSION
SLUDGE LEVEL BY EYE
PROBE No. 2 ELEV.
PROBE No. I ELEV.
SUSPENDED SOLIDS
I I I
HOPPER BOTTOM ELEV.
I I I I I I
FIGURE 32
1000 2000
SUSPENDED SOLIDS CONG, mg/l
SUSPENDED SOLIDS AND LIGHT TRANSMISSION VERSUS DEPTH IN
SEDIMENTATION TANK
3000
-------
00
I- I
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S 5
cr.
15 6
00 7
IT
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Is
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16
17
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10
20
30
PERCENT LIGHT TRANSMISSION
40
50
60
70
80
90
iao
6-*"x^ f
i I \ \ I
I I I I I
FIGURE 33
TRANSMISSION
SUSPENDED SOLIDS-
HOPPER BOTTOM ELEV
SVI = 565
PROBE No. 2 ELEV.
PROBE No. I ELEV
I I I I I
3000
1000 2000
SUSPENDED SOLIDS CONC. mg/l
SUSPENDED SOLIDS AND LIGHT PENETRATION AS A FUNCTION OF DEPTH
IN SEDIMENTATION TANK
-------
00
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60
50
40
30
Q
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1.0
20000
20OO 4000 6000 8000 10000 12000 14000 16000 18000
SUSPENDED SOLIDS mg/l
PERCENT LIGHT TRANSMISSION VS. RETURN SLUDGE SUSPENDED SOLIDS
FIGURE 34 CONCENTRATION HACH FALLING STREAM TURBIDIMETER 0.25" LIGHT PATH
-------
Sludge Blanket Levels
Average operating parameters at the LBWRP for the month of
June, 1974, are presented in Table 5. Using equation 4 with
values from Table 5 minimum and median return sludge flow rates
per clarifier were estimated to be approximately 0.26 mgd and
1.11 mgd, respectively. The minimum return rate was initially
adjusted to 0.3 mgd since flows less than this led to plugging
of the control butterfly valve. Since further concentration of
the sludge was expected following establishment of a sludge
blanket, the median return rate was set at 0.8 mgd. Minor adjust-
ment of these initial return rates were made during the study in
response to changing sludge settling characteristics.
During the first week of the study period, it was observed that
actuation of probe no. 2 with subsequent full opening of the
return control valve caused considerable disruption of the
clarifier. With control valve full open, the return rate increased
to such an extent that the water surface in the clarifier momen-
tarily fell below the effluent weirs. This was obviously an
unwarranted situation and, as a result, probe no. 2 was discon-
nected from the control circuitry. Actuation of probe no. 2 was
still recorded but activation did not affect control valve position.
Thus, only two valve positions were used in the remainder of the
study, the minimum position with probe no. 1 deactivated and the
median position with probe no. 1 activated.
Profiles of percent light transmission in the water column above
the return sludge hoppers are plotted in Figures 35 to 38. The
Figures are arranged in order of increasing SVI. In Figure 35
mixed liquor SVI was 51 which indicates that the sludge was
capable of very dense compaction. Sludge level in the return
hoppers was quite low in the early morning low flow period but
increased with increasing plant flow. By noon, the sludge
interface reached probe no. 1 which caused valve actuation and
increased return sludge flow to 0.8 mgd. Timer duration, set
to 10 minutes in this test, was too long since the return hopper
89
-------
TABLE 5
MONTHLY AVERAGE OPERATING PARAMETERS
LONG BEACH WATER RENOVATION PLANT
June, 1974
Minimum daily flow 3,1 mgd
Peak daily flow 13.2 mgd
Average daily flow 9,1 mgd
Mixed liquor suspended solids 1600 mg/1
Return sludge suspended solids 5400 mg/1
Number of final clarifiers in service 5
90
-------
w.s.
2
3
4
5
6
7
8
9
10
II
12
13
14
15
16
17
18
0700
PROBE No. I
ACTUATION
Qmin=0.3mgd Qmed-0.8mgd
AVG. SVI = 5I Timer = IOmin
(changed to 2 min following probe
actuation- I200hrs)
UI
u_
•»
CO
98
% LIGHT
PROBE No. 2 ELEV.
TRANSMISSION
CLARIFIER FLOOR ELEV.
00
t
UJ
o
PROBE No. I ELEV.
0800
0900
1000
1100
1200
1300
1400
1500
1600
1700
FIGURE 35
PRORLES OF LIGHT TRANSMISSION
-------
W.S.
to
LU
LJ
CO
O
UJ
CD
10
Q.
UJ
O
12
13
14
15
16
17
18
0700
% LIGHT
Qmin =0-3 mgd
Qmid=0.8 mgd
Timer= 2 min
SVI = 53
'98
PROBE No. 2 ELEV.
PROBE No. I ELEV.
CLARIFIER FLOOR ELEV.
0800 0900 1000 1100 1200
8-13-74
1300
1400
1500
1600
1700
FIGURE 36
PROFILES OF LIGHT TRANSMISSION
-------
U)
W.S.
H-
^
UJ
^
CO
*
j
CD
i
2
3
4
5
5
6
7
8
»
10
14
15
17
18
0800
0900
PROBE No.lOPER
s /
% LIGHT
TRANSMISSION
Qmin = 0-3 m g d
Qmed=0.8mgd
Timer= 5 min
SVI = 117
99
PROBE No. 2 ELEV.
90
TOJ8PROBE No. I ELEV.
I
CLARIFIER FLOOR ELEV.
10
HOPPER
BOTTOM
1000
100
1200
1300
1400
1500
1600
1700
1800
FIGURE 37
PROFILES OF LIGHT TRANSMISSION
-------
VJD
Ul
U
CO 7
o
LJ
CD
10
HI
o
13
w.s.
14
15
16
17
18
0900
% LIGHT
TRANSMISSION
PROBE No. 2 OPERATION
PROBE No. I OPERATION
98 Qmin=0.45mgd
Qmed=0.8 mgd
Tlmer = 5mln
SVI - 522
97 PROBE No. 2 ELEV.
PROBE No. I ELEV.
\ CLARIFIER FLOOR ELEV.
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
FIGURE 38
PROFILES OF LIGHT TRANSMISSION
-------
was almost emptied of sludge. Interface height subsequently
increased but did not reach the level of probe no. 1.
In a subsequent test, timer duration was reduced to two minutes
to avoid excessive drawdown of the sludge blanket level. In
this case, however, sludge interface never reached the level of
probe no. 1 and no valve actuation was noted as shown in
Figure 36. SVI was so low and, hence, the sludge blanket so
compact that the minimum return flow of 0.3 mgd was more than
sufficient to keep the blanket below probe no, 1. Using equation
6 with average monthly parameters from Table 5 and an SVI of 53,
the return rate necessary to maintain a constant blanket level
under peak flow conditions is estimated to be about 0.24 mgd.
The fact that a return rate of 0.3 mgd did not allow a buildup
in the sludge blanket seems to substantiate the validity of
equation 6.
Constant sludge blanket levels were maintained when the SVI was
in a more normal range of 100 to 150 as shown in Figure 37.
Even so, the minimum return rate was too large to allow a sludge
blanket during the low flow period. This was the general pattern
observed throughout the study period. Hopper levels were drawn
down during low flow periods but subsequently increased as plant
flow rate increased. If the SVI was greater than about 60 or 70,
the blanket would eventually reach the level of probe no. 1.
Subsequent probe actuation was normally quite effective in maintain-
ing the blanket at or below probe no. 1.
Sludge blanket levels increased above probe no. 1 only during
periods of sludge bulking. Light transmission profiles with a
mixed liquor SVI greater than 500 are shown in Figure 38. Under
these conditions, the sludge interface became very diffuse and
would normally reach the level of probe no. 2 causing activation.
Recall that activation of probe no. 2 was recorded but caused
no change in return flow rate. Return sludge control equipment
continued to function in an acceptable manner although the
bulking wats, at times, quite severe. Generally, the probes would
not activate during the low flow period but once activated would
95
-------
stay on continuously until flow rate again decreased.
Strip chart recordings of light transmission at the level of
probe no. 1 and probe actuation are presented Figures 39 and 40.
For data in Figure 39, SVI was 534 and probe no. 1 was actuated
during most of the high flow period between 1000 and 1600 hours
and deactivated during the early morning low flow period. Light
transmission and probe actuation recordings for an SVI of 183
are shown in Figure 40, Both charts are representative of normal
probe operation at their respective SVI levels.
The percentage of time a probe was actuated was found to be a
function of mixed liquor SVI. Ranges observed in the time of
probe actuation are presented in Table 6. Actuation rarely, if
ever, occurred below an SVI of 50. At an SVI of 100, the probe
was never actuated more than 10 percent of the time. The length
of probe actuation increased rapidly with increasing SVI up to
values of about 400 above which probe actuation occurred between
40 and 70 percent of the time.
Probe no. 2 rarely actuated at SVI values below 200 and most of
the actuation which did occur was thought to be due to periodic
plugging of the probe by biological solids. Above SVI levels
of 400, however, probe actuation did occur regular y during the
peak flow period.
Scheduled Maintenance
A point of major concern during the study was whether the Keene
probes would become fouled with return sludge or other biological
growths. If fouling occurred, the probe would react as if it
sensed sludge resulting in unnecessary as well as undesired valve
operation.
During periods of rising sludge, the probes were observed to
actuate even though the turbidimeter showed no decrease in light
transmission. The probes rarely actuated for periods longer than
the timer interval. This was undoubtedly caused by clumps of
rising sludge passing the probe and causing activation. The
rising sludge apparently passed by the probe without fouling
96
-------
IUW
90
80
70
60
50
40
20
10
n
««*>
sv
= 534
^ 1
t>
b
pi
PROBE AND VALVE
ACTUATION
rfr
• •
1r
u
-^
J
^^^^^^^B^HB
i ^Bjpp^^^w^^^^
1T
4
H
pu
r
»
1
Ut«
t
%
M*
% LIGHT TRANSMISSION AT
PROBE No.
100
I2M 2AM
FIGURE 39
4AM 6AM SAM 10AM 12 N 2PM 4PM 6PM
LIGHT TRANSMISSION AND PROBE ACTUATION
8PM
10 PM
I2M
-------
100
CO
SVI=183
PROBE AND VALVE
ACTUATION
% LIGHT TRANSMISSION AT
PROBE No. I
I001
I2M 2AM
FIGURE 40
4AM 6AM SAM 10AM I2N 2PM 4PM 6PM
LIGHT TRANSMISSION AND PROBE ACTUATION
8PM
10PM
IZM
-------
TABLE 6
PROBE ACTUATION
Time of Probe Activation
Expressed as a Percentage
of Total Time
SVI Range Probe No. 1 Probe No. 2
50 0-2 0
100 1-10 0-1
200 10-45 0-2
300 30-60 0-4
400 40-70 0-20
500 40-70 0.1-20
600 45-70 3-20
99
-------
because the probes deactivated following the timer interval.
In any event, the problem was not serious and did not signifi-
cantly affect probe performance.
Fouling of the probes to such an extent as to cause continuous
probe actuation was observed three times during the study period.
In all cases, the fouling material was easily removed by raising
and lowering the probe in the water column. Based upon this
experience, the probes should be cleaned at least weekly to
avoid gradual accumulations of biological growths,
SUMMARY
Based upon results collected during a two-month study period, the
following conclusions can be drawn with regard to return sludge
flow control using Keene probes.
1. Return sludge flow control is practical and offers the
advantage of increased return and waste sludge solids
concentrations.
2. In general, the sludge blanket could be maintained at a
constant level during peak flow conditions but was always
drawn down during low flow periods.
3. A definite sludge blanket interface existed for SVI values
below about 200. Increasing SVI resulted in a gradual loss
of the interface until at SVI levels greater than 500 no
definite interface existed. Instead a gradual increase in
solids concentration was observed with no distinct liqaid-
sludge interface.
4. Sludge bulking did not adversely affect probe performance
although the time of probe actuation increased significantly,
5. Equations 4 and 6 can be used to estimate proper return
sludge flow rates.
6. Fouling of the probes was not a severe problem and could
generally be avoided by regular probe cleaning on a weekly
basis.
7. Two probes were not required to maintain a constant sludge
blanket level and probe no. 2 was not used to control valve
100
-------
operation in this study. In future designs, probe no. 2
can either be completely eliminated or used as an alarm
to signal adversely high blanket levels. Should the probe
function as an alarm, a timer should be included so that
the probe must sense sludge continuously for at least 15
minutes before the alarm is actuated.
Equalization of wastewater flows prior to secondary
treatment is being considered as a method of increasing
plant capacity. Under these conditions, flow rate to the
final clarifiers would be constant. Return sludge control
equipment could then maintain a constant sludge blanket
level at all times and not just during the high flow period,
Maximum return and waste sludge concentrations would also
be realized.
101
-------
SECTION VIII
WASTE ACTIVATED SLUDGE - FLOW CONTROL
INTRODUCTION
The fundamental equation describing cell growth in a biological
reactor is
Where dX/dt = growth rate of microorganisms
Y = cell yield coefficient
dF/dt = rate of food utilization
b = endogenous respiration coefficient
X = cell mass
Equation 1 basically states that net production of new cells is
a function of both rate of food utilization and loss of cells
due to endogenous respiration. Dividing equation 1 by X yields
dX/dt = y dF/dt _ b (i)
X X
In this equation
X -A = mass of cells in the system ,_.
dX/dt c mass of cells grown per day
If the biological reactor is at steady state, or nearly so, the
mass of organisms grown per day will equal the mass of organisms
wasted per day. Thus, if the system is at steady state, 6 will
\^-
equal the average retention time of a cell in the system which is
commonly referred to as mean cell retention time (MCRT) . Also
in equation 2
dF/dt = rate of food utilization (4)
X mass of organisms in system
102
-------
= food to microorganism ratio (F:M)
Thus,
i- = Y (F:M) - b (5)
c
The terms Y and b should be approximately constant for a given
waste and, hence, MCRT and F:M are inversely proportional.
Lawrence and McCarty, applied equation 1 to the activated sludge
process and found that effluent substrate concentration was a
function of the mean cell residence time, decreasing with increas-
ing MCRT, Since MCRT is, in turn, related to the food to micro-
organism ratio, it implies that either parameter can be used to
theoretically describe effluent quality from the activated sludge
process. In practice, however, effluent quality is not as
pronounced a function of MCRT. This is because effluent quality
is determined to a large extent by settling properties of the
mixed liquor. Nevertheless, MCRT and F:M have a sound theoretical
basis for use as control parameters for the activated sludge
process.
Which of the parameters, either MCRT or F:M, to use in practice
has been the subject of much debate in the technical literature.
Use of F:M ratio requires considerable laboratory work since it
is necessary to know both the amount of food removed and the
mass of organisms in the system. This requires tests for total
BOD or COD in the influent and soluble BOD or COD in the effluent
as well as volatile suspended solids, VSS, in the aeration tanks.
COD tests are usually used to avoid delays associated with the
BOD test. In addition, VSS is a relatively poor measure of the
true active mass of microorganisms in the mixed liquor (sometimes
referred to as viability). In practice, however, this latter
disadvantage may not be significant since the active mass is
probably a fairly constant percentage of the VSS. However,
little laboratory data exists to substantiate this latter claim.
Conceptually MCRT is an easier parameter to use. Should the
operator desire a 5-day MCRT, he need waste 20 percent of the
103
-------
total plant solids each day. Viability or active mass of the
mixed liquor need not be considered since if 20 percent of the
total solids are wasted daily, then 20 percent of the active
mass is also wasted. Thus, the operator must know the total
solidsf TS, in the system as well as the TS lost from the system
each day.
In LACSD practice, the MCRT is normally used as the control
2
parameter for the activated sludge process, . A given fraction
of solids, therefore, must be wasted daily. It remains then
to describe control schemes for solids wasting.
CONTROL SCHEMES FOR SOLIDS WASTING
Two different control schemes have been proposed to accomplish
solids wasting from the activated sludge process. One involves
wasting mixed liquor directly from the aeration tank while the
other involves wasting from the return sludge line coming from
the secondary clarifier. Both of these will be described so as
to better evaluate the advantages and disadvantages of control
techniques used by LACSD.
Wasting from the Aeration Tank
A schematic diagram of an activated sludge process in which
wasting is accomplished directly from the mixed liquor is shown
in Figure 41. The wasting rate (Q ), required to achieve a
given MCRT in this system can be determined through use of
equation 3. The total mass of solids in the system is the sum
of solids held in the aeration tank and final clarifier. Total
solids mass in the aeration tank can be described as XV , where
Si
X is the concentration of solids if the aeration tank is complete-
ly mixed or the average concentration if the reactor is not.
Estimating solids mass in the secondary clarifier is more diffi-
cult since a sludge blanket normally forms at the bottom of the
clarifier. Average solids retention time in the sludge blanket
is difficult to ascertain. Burchett and Tchobanoglous, suggested
that the mass of organisms in the secondary clarifier is approx-
imately equal to the volume of the clarifier times the MLVSS, V X,
s
104
-------
CL..X
Q
h.
t
AERATOR
Va,X
Qr ,Xr
JCLARII
~~v8
Q =
Qw =
Qr =
va •
V8 =
X =
xr =
PRIMARY EFFLUENT FLOWRATE
WASTE SLUDGE FLOWRATE
RETURN SLUDGE FLOWRATE
VOLUME OF AERATOR
VOLUME OF CLARIFIER
MIXED LIQUOR VOLATILE SUSPENDED SOLIDS
CONCENTRATION
SECONDARY EFFLUENT VOLATILE SUSPENDED
SOLIDS CONCENTRATION
RETURN SLUDGE VOLATILE SUSPENDED SOLIDS
CONCENTRATION
SCHEMATIC DIAGRAM OF ACTIVATED SLUDGE PROCESS
FIGURE 41 WITH WASTING FROM MIXED LIQUOR
105
-------
This is strictly true only if the. detention time of the solids in
the clarifier equals the liquid detention time. Nevertheless, it
should provide a reasonable approximation of the true mass. Deaner
and Martinson, have recently questioned whether cell mass stored
in the final clarifier should be included in the cell balance.
While this point is of theoretical interest, it is beyond the
scope of this report and cell storage in the final clarifier will
be considered in the cell balance,
Organisms are wasted from the system from two places, intention-
ally from the aeration basin and unintentionally in effluent from
the secondary clarifier, A third source of possible wasting is
the surface skimmings collected in the secondary clarifier. Such
skimmings may represent a significant loss of solids if foaming or
sludge baulking occur in the aeration system. Under normal operation,
however, 'this loss is not significant and need not be considered
in this discussion.
Mass of solids wasted intentionally from the aeration tank is
represented by XQ , while that in the effluent as (Q-Q )X .
w we
Using equation 3, MCRT can be described as
xv + xv
XQw + (Q-Qw)Xe
If the treatment plant is operating properly, effluent solids loss
should be a small fraction of the solids intentionally wasted.
Under these conditions, equation 6 can be simplified to
« - X(Va + V (7)
QwX
Solving for Q
w
c
If solids are wasted directly from the mixed liquor, the wasting
rate is a function only of the aeration and clarifier tank
volumes and the desired MCRT, No laboratory measurements are
106
-------
necessary. Despite these advantages, the number of treatment
3 4
plants employing this control scheme is limited, ' . The
reason for this is that a greater volume of waste sludge must
be handled and an additional "/aste activated sludge clarifier
is required. In addition, laboratory measurements required to
waste from the return sludge line are usually performed as a
routine part of plant operation. As such, wasting from the
mixed liquor offers little advantage in saving laboratory work
since the control tests are performed anyway.
Wasting from the Return Sludge Line
A schematic diagram of an activated sludge process with sludge
wasting from the return sludge line is shown in Figure 42.
Employing the same procedure as previously described, the MCRT
can be described as
n _ XV + XV,
8c - — $ - * - (9)
Qw Xr + (Q-Qw)Xe
Solving equation 9 for Q gives
Q = x(va + ys) - ec(Q-Qw)xe
"W -
V Q
Vc
Since Q is normally much smaller than the plant flow rate, Q, it
can be neglected on the right side of equation 10 allowing a
direct solution for Q .
*
Q = a a - ce
w -
X 9
r c
Thus, to determine the required wasting rate from the return
sludge line, the plant operator must know the volumes of both the
aerator and final clarifier and must measure mixed liquor, return
sludge and secondary effluent suspended solids concentrations.
Since return sludge is more concentrated than mixed liquor, a
smaller volume of waste sludge need be handled and additional
waste sludge clarifiers are not required. These considerations
107
-------
vs =
X =
AERATOR
Va,X
CLARIFIER )Q-Qw»xe
vs
Qr ,Xr
Q = PRIMARY EFFLUENT FLOWRATE
Qw= WASTE SLUDGE FLOWRATE
Qr - RETURN SLUDGE FLOWRATE
Va = VOLUME OF AERATOR
VOLUME OF CLARIFIER
MIXED LIQUOR VOLATILE SUSPENDED SOLIDS
CONCENTRATION
SECONDARY EFFLUENT VOLATILE SUSPENDED
SOLIDS CONCENTRATION
RETURN SLUDGE VOLATILE SUSPENDED SOLIDS
CONCENTRATION
SCHEMATIC DIAGRAM OF ACTIVATED SLUDGE PROCESS
FIGURE 42 WITH WASTING FROM RETURN SLUDGE LINE
108
-------
have led the LACSD to incorporate sludge wasting from the return
sludge line in its activated sludge plant designs. The LACSD
recognizes, however, that wasting from the mixed liquor is a
viable alternative and that the particular wasting scheme in
any design must be chosen after consideration of all factors.
CONTROL OF RETURN SLUDGE WASTING
Several different schemes have been used to control solids
wasting from the return sludge line. Two of the most popular
control techniques are (1) wasting a constant percentage of the
return sludge flow (sometimes referred to as hydraulic control)
and (2) wasting a fixed volume of return flow. Both of these
control schemes will be described since the control calculations
and required laboratory measurements depend on the techniques
chosen.
Wasting a constant percentage of the return sludge flow was
described by Walker, in 1965 and is sometimes referred to as
hydraulic control. Referring to Figure 42, to maintain a given
MCRT, it is necessary to waste 100/MCRT percent of the total
plant solids each day. However, 100/MCRT percent of the return
sludge flow can not be wasted since solids make several passes
through the return line each day. Total flow rate through the
aeration tank and secondary clarifier is Q + Q . Thus, the
liquid makes a total of (Q + Q ) / (V + V ) passes per day. The
r a s
solids should make the same number of passes per day provided
there is no accumulation in the secondary clarifier which is
unlikely. Thus, for a conventional plant, the continuous wasting
rate, W, figured as a percent of the gross return sludge flow
rate (Q + Q ) can be calculated as
(Va + V (12)
(Q + Qr)
For a given plant, the aeration and clarifier tank volumes are
fixed. Thus, the operator need know only the desired MCRT, average
plant flow rate, and return sludge flow rate to calculate the
109
-------
percentage of return sludge to be wasted. Mixed liquor and return
sludge concentration need not be determined. Should mixed liquor
and return sludge concentrations vary diurnally, as they usually
do, it in no way affects the wasting percentage, W. One disad-
vantage of this control technique, however, is that variations in
return sludge flow rate necessitate readjustments of the wasting
percentage. If the return rate is constant, as it is in many
plant designs, the wasting percentage is fixed. But if it varies,
as it might if Keene probes were used to maintain a constant sludge
blanket level (see Section VII) constant readjustment of the wasting
percentage would be required.
Operating practice at LACSD activated sludge plants involves using
equation 11 to calculate a waste sludge flow rate. 24-hour composite
samples of mixed liquor, return sludge and secondary effluent sus-
pended solids collected the previous day are used in equation 11 to
predict the wasting flow rate. Thus, calculations are always one
day behind. This is not a serious drawback, however, since mean
cell residence times are normally on the order of 5 to 15 days and
operating parameters should not change significantly in the course
of a single day-
It is important that 24-hour composite samples be used to calculate
mixed liquor, return sludge, and effluent suspended solids concen-
trations used in equation 11. Diurnal variations in these parameters
would be expected in any treatment plant experiencing diurnal flow
variations. A representative sample of return sludge concentrations
experienced at the LBWRP is shown in Figure 43. Samples were
collected every 15 minutes over a 24-hour period in 1973 with each
bar representing the average results of a 4-hour composite sample.
Return flow rate was constant during the time of sampling. Equa-
tion 11 only predicts the flow rate required to waste a given mass
of solids. Therefore, composite samples are an absolute neces-
sity. In addition, the flow rate predicted by equation 11 must
be maintained constant so as to waste evenly from all sludge
concentrations experienced throughout the day.
110
-------
ouvv
E 5000
M
^JCENTRATION
e samples)
^
o
o
o
8 0 300°
UJ c"
e> 5
1"
^ .C 2000
Z *
tr *-*
UJ 1000
(T
1
1
_
2260
—
1
4270
1
1
5255
1
1
1
1
1 1
^_^_
4283
1
3790
1
2598
1
1
0700
1100
1500
1900 2300
11/23/73
0300
•> 11/24/73
0700
FIGURE 43
DIURNAL VARIATION IN RETURN SLUDGE CONCENTRATIONS AT
LONG BEACH WATER RENOVATION PLANT
-------
LACSD ACTIVATED SLUDGE WASTING FACILITIES
A schematic diagram of the waste sludge control system employed
at LACSD activated sludge plants is shown in Figure 44. Heart
of the system is the flow measurement device used to generate a
control signal. Any number of flow measuring devices, including
orifice plates, venturi meters, magnetic and propeller flowmeters,
could be used. The only requirement is that the device generate
a signal that is a function of flow rate, LACSD design practice
has been to use propeller meters which are considerably less
expensive than comparable magnetic flowmeters and create less
headloss than orifice plates. The main disadvantage of a pro-
peller meter is that it is subject to fouling by material con-
tained in the flowstream.
Treatment plants which employ anaerobic digestion of primary
sludge commonly return digested supernatant back to the primary
tanks. Depending on digester performance, the supernatant may
contain quantities of stringy material which could buildup in
the activated sludge mixed liquor. If such were the case, pro-
peller meters would require regular cleaning to avoid fouling.
All of the LACSD activated sludge plants using propeller meters
discharge primary sludges back to the sewer for subsequent treat-
ment at the District's Joint treatment plant. Thus, the waste
sludge is relatively free of fouling material.
Examination of maintenance records indicated that propeller meters
in the waste sludge lines were cleaned about twice a year on the
average. Generally, cleaning was performed only if the operator
observed erratic response from the meter. A propeller meter
removed from the waste sludge line after three months of contin-
uous operation was found to be completely free of fouling material,
The pulse signal generated by the propeller meter is sent to a
pulse to current converter. Converter output is a 4 to 20 ma
signal proportional to flow rate. This signal is compared with
a set point value and used to control the position of a motorized
throttling valve. The signal also actuates a recorder, flow
112
-------
AERATION TANK
PROPELLER
FLOWMETER
to
SECONDARY EFFLUENT
RETURN SLUDGE
WET WELL
LOCAL
INDICATION a
TOTALIZATION
P'l
CONVERTER
THROTTLING
VALVE
O
I
O
O
L.
RECORDER
AND
TOTALIZER
CURRENT
TRIP
WASTE
ACTIVATED
SLUDGE
T
SET POINT
(MGD)
NO WASTE
ACT. SLUDGE
ALARM
FIGURE 44
SCHEMATIC DIAGRAM OF WASTE SLUDGE FLOW CONTROL SYSTEM
-------
totalizer, and a no-flow alarm. Thus, if something should
accidently stop the propeller, an alarm is immediately sounded
alerting the operator.
The valve actuator is either an electro-hydraulic or electro-
pneumatic device which positions the actuator stem proportionally
to the input current command signal. Both butterfly and diaphram
valves are currently used in LACSD installations. Both types of
valves have given good service.
OPERATIONAL EXPERIENCE
Daily operational practice at LACSD activated sludge installa-
tions utilizes the automatic collection of 24-hour composite
samples (one sample every 15 minutes) of aeration tank mixed
liquor, return sludge, and secondary effluent suspended solids.
These values are then applied to equation 11 to predict the waste
sludge flow rate required to achieve a certain mean cell resi-
dence time. It is essential that 24-hour composite samples be
used since solids concentrations will vary diurnally- Also,
it is essential that the wasting rate calculated from equation 11
remain constant throughout the day so as to waste evenly from all
return sludge concentrations.
The technique of wasting a constant flow rate from the return
sludge line has been used in LACSD installations for many years.
The control equipment functions with a minimum of maintenance.
However, the main test of any sludge wasting technique is whether
it actually wastes the correct mass of cells and can maintain
desired MCRT values. Years of operational experience with daily
treatment plant solids inventories indicates that the wasting
technique and associated control equipment function properly.
Analysis of several months operational data indicated that, in
general, waste flow rate could be maintained within about 2 or 3
percent of the desired set point value. With a fixed set point,
however, daily waste volumes were reproducible to within 0.5
percent.
Certain characteristics of the control equipment are worthy of
114
-------
discussion. Should the propeller meter become fouled, control
signal to the electronic controller will indicate a no-flow
condition. The controller will signal for additional valve
opening in an attempt to readjust the flow rate to the desired
set point value. This will continue until the valve is in a full
open position and solids are being wasted at an extremely high
rate. Since the propeller meter is fouled, it will continue to
register zero flow. Fortunately, the no-flow alarm will actuate
under these conditions alerting the plant operator. If the
operator is slow to respond to the alarm, however, considerable
solids will be lost from the plant.
Conditions somewhat less extreme than the above will result if
the propeller meter loses its calibration. This could happen,
for example, if fouling material slowed propeller response to a
given flow rate. Under these conditions, an excessive amount of
solids would be wasted from the plant but no alarm would be
sounded to alert the operator. His only control is to watch the
solids inventory in the plant and check for any sharp reduction
in total plant solids. Loss of calibration in this manner has
not been a significant problem in LACSD installations.
One might suspect that control valve plugging by suspended solids
would be a potential problem. It is not, however, because of the
nature of the feedback control loop. Should the control valve
plug (as butterfly valves, in particular, are prone to do when
only partially open) the decreased flow rate would be sensed by
the flowmeter. The controller in turn would call for increased
valve opening to readjust the flow rate. Thus, valve plugging
is not a problem unless the line remained plugged with the valve
fully open which is extremely unlikely.
115
-------
SECTION VIII
REFERENCES
1. Lawrence, A.W., and McCarty, P.L., "Unified Basis for
Biological Treatment Design and Operation", Journal of the
Sanitary Engineering Division, ASCE, Vol. 96, No. SA3,
757-778, (1970)
2. Jenkins, D., and Garrison, W.E., "Control of Activated Sludge
by Mean Cell Residence Time." J. Water Pollution Control
Fed., 40, 1905, (1968)
3. Burchett, M.E., and Tchobanoglous, G., "Facilities for
Controlling the Activated Sludge Process by Mean Cell
Residence Time." J. Water Pollution Control Fed., Vol. 46,
No. 5, (may, 1974)
4. Garrett, M.T., Jr., "Hydraulic Control of Activated Sludge
Growth Rate." Sew. & Ind. Wastes, 30, 253, (1958)
5. Walker, L.F., "Hydraulically Controlling Solids Retention
Time in the Activated Sludge Process." J. Water Pollution
Control Fed., 43, 30, (1971)
6. Deaner, D.G., and Martinson, S., "Definition and Calculation
of Mean Cell Residence Time." J. Water Pollution Control
Fed., 46, 2422, (1974)
116
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SECTION IX
COMPUTER CONTROL APPLICATIONS
INTRODUCTION
The Sanitation Districts of Los Angeles County have developed an
on-line computerized data management system capable of providing
a treatment plant operator with daily reports including opera-
tional calculations and effluent compliance checks. The system
also produces monthly summaries of all data for management
review and monitoring reports submitted to regulatory agencies.
The evolution of the present system was a staged process, each
step of which was a response to increasing demands for additional
information relative to the status of treatment plant operations.
HISTORY
During the mid-1960's the Sanitation Districts operated four
activated sludge treatment plants. To provide management with
monthly status reports on operation conditions, a system was
devised whereby the operator of each plant entered certain daily
data onto summary sheets. At the end of the month, these sheets
were forwarded to the administration office where an engineer,
with the aid of the desk top calculator, performed certain
calculations. The raw data and calculations were then typed
onto final sheets and circulated among management. Obviously,
this procedure provided no opportunity to immediately recognize
at the operational level significant trends in other than raw
data. In response to the heavy demand this procedure placed
upon the engineer's time, his role was eliminated by sending
the raw data directly to the Districts' Data Processing Depart-
ment at the end of each month for keypunching. The Districts'
117
-------
computer at that time consisted of a Univac 9300, a business
oriented computer which could, however, support FORTRAN language
programs. The computer performed the necessary calculations,
and the results, along with the raw data, were typed onto
appropriate sheets for circulation among management.
By 1970 it became obvious that some method was needed to perform
many of these calculations on a daily basis and make the results
available to the operator as soon as possible, so that un-
desirable operating trends could be recognized and quickly
corrected. After review of possible alternatives, the
Sanitation Districts chose to install teletype terminals at
each of the treatment facilities and to lease time-sharing
computer services. In addition, the Districts leased a high
speed printer terminal at the administrative office building
to provide, on a monthly basis, the summaries of data for
management review. The main criterion for selection of a
commercial time-sharing service organization was that the
stored data base be available to both low speed teletype
terminals, to be installed in each treatment facility, and to
the high speed printer to be installed at the administrative
office. In addition, as a secondary criterion, the commercial
organization needed to provide some programming assistance and
expertise to assist the Districts' staff in developing the
necessary software. In 1970 there were few organizations which
provided services meeting both criteria.
From 1970 through mid-1974 this computerized data management
system underwent several revisions in number of calculations
performed and format of the monthly summaries of data. As the
Districts placed three new activated sludge treatment plants
into service (1970-1973), each was provided with a teletype
terminal and utilized the computer services.
In mid-1974 two events occurred which required a significant
expansion of the District's computer services. The first was
118
-------
the decision to obtain an in-house computer. Usage of the com-
mercial time-sharing services, both for the treatment plant data
and, also, for various other work combined with increased
accounting and personnel workloads on the Univac 9300, made it
obvious that obtaining in-house hardware would be more cost-
effective than continuing to lease such services. The second
factor was the issuance of two new independent discharge permits
for each of the seven activated sludge treatment plants. These
new permits were promulgated under the National Pollutant Dis-
charge Elimination System (NPDES) Permit Program and under the
California Water Code. Each permit requires that monthly moni-
toring reports containing extensive statistical evaluations of
data be prepared for each facility. The revised computer system
now in use incorporates the previous system, which performed
plant operational calculations only, and a complete data manage-
ment system which monitors the status of all information re-
quired for reporting purposes, performs daily effluent statisti-
cal calculations and informs operations' personnel of violations
of specified effluent limits. In addition, the data management
system can inform the operator which data, while not constitu-
ting violations of discharge requirements, are not within a
desired range of values.
EQUIPMENT
Hardware
Each treatment plant is equipped with a Teletype Corporation TWX
model 33 terminal capable of a 110 baud (bits per second) trans-
mission rate. The information is transmitted over normal voice
grade telephone lines to the Districts' administrative office,
the site of the computer hardware. The computer is an IBM 370
model 125. The Central Processing Unit (CPU) of the computer
is a multiprogramming, fixed partition environment having a 196K
byte real storage memory. Supporting the CPU are three IBM
model 3340 disc drive storage units each with a 70M byte storage
119
-------
capacity- The Virtual Storage (VS) concept of exchanging CPU
storage with disc storage is utilized to effectively increase
the CPU capacity to 1.4M bytes. Additional hardware in use
includes an IBM model 3504 card reader, an IBM model 3203 high
speed printer capable of 1100 lines per minute, two IBM model
3410 tape drives capable of 800 or 1600 bits per inch recording
densities and operating speeds of 50 inches per second, and four
local IBM model 3270 CRT terminals operating at channel speeds.
These latter terminals are utilized by various departments at
the administrative office,
Software
There are two operating systems which control all work in the
computer. The first, Disc Operating System/Virtual Storage (DOS/
VS) supervises all work not involving the on-line applications,
that is, the computer jobs submitted in batch at the main office.
The on-line applications, which include the treatment plant data
management system, are controlled by the second operating system,
Customer Information Control System/Virtual Storage (CICS/VS),
working in conjunction with DOS/VS.
One of the four fixed partitions of the CPU is dedicated exclu-
sively to CICS. This partition has a 40K byte real storage
capacity. In addition, CICS shares up to an additional 66K byte
real storage capacity with the other partitions of the CPU, the
amount shared at any time depends upon the demand DOS places
upon this capacity- The Virtual Storage operation gives the
CICS partition an effective working capacity of 528K bytes.
The software required to run the on-line time-sharing operations
consists of approximately 240,000 lines of programming instruc-
tions, most of which were supplied by the equipment hardware
manufacturer. In addition, there are approximately 12,000 lines of
programming instructions to operate the data management system
described herein. These latter instructions are broken up
into separate programming modules or programs. All programs are
120
-------
written in PL/I language.
DATA MANAGEMENT SYSTEM
The operation of the existing Water Renovation Plant Data Mana-
gement System (WRPDMS) will be described in seven sections:
Overview, Data Preparation, Data Entry, Plant Operational Calcu-
lations, Effluent Compliance Calculations, Reports, and System
Management Programs.
Overview of System
Shown in Figure 45 is a schematic diagram of the WRPDMS. Note
that not all operations are performed under CICS, the on-line
portion of the system. Batch processing, which includes report
generations, file maintenance, and performing 30-day average
calculations are reserved for the p.m. shift when the on-line
system is not in service. Calculation of the 30-day averages
is a time consuming process and if performed on-line will
interrupt all other work of the computer. Hence, by reserving
these calculations for the p.m. shift, the time spent at a
terminal is decreased and the overall computer throughput is
increased.
Figure 46 illustrates the interrelationship of the various
programs developed for the on-line system. There are nine
different transaction options the operator can use to enter
or retrieve stored data and calculation results from the system.
The step-by-step process of each of these transactions is shown
in Figure 46 and each will be described below.
Data Preparation
Shown in Figure 47 are the raw data sheets used at the Long Beach
Water Renovation Plant. All other treatment plants use nearly
identical sheets; however, the first and last pages vary with
each plant to account for differences in numbers of discharge
points and numbers of aeration systems. These sheets include
all of the data gathered at the five activated sludge treatment
121
-------
OPERATING
SYSTEM
(DOS/VS)
[ Report
Specif i cation
Data Base
Information
DATA BASE/
DATA COMMUNICATION
SYSTEM
(CICS/VS)
ON-LINE
APPLICATION
PROGRAMS
OFF-LINE
APPLICATION
PROGRAMS
Performance
Statistics
Ana lyzer
Reorganization/
Backup Module
Data
Base
Reports
Performance
Statistics
Performance
Reports
FIGURE 45
WATER RENOVATION PLANT
DATA MANAGEMENT SYSTEM
122
-------
(UPDATE , LIST , RECALC,
LOOKUP, DIGEST, EFFCMP)
(STATUS)
r(CALCS .STORE)
(C A LCS, STORE, UPDATE)
(RECALC .LOOK.UP
DIGEST, EFFCMP)
(UPDATE ,STORE)
RECALC,LOOKUP)
(DIGEST,EFFCMP)
(EFFCMP)
UPDATE
STORE)
(C A LCS, RECALC, LOOKUP)
(CALCS,RECALC)
(DIGEST,
EFFCMP)
(CALCS.RECALC)
Solids
Handling
Calcs
(CALCS, RECALC)
(CALCS, RECALC, LOOK UP)
(CALCS,RECALC,
DIGEST)
(CALCS,
RECALC,
EFFCMP)
(CALCS,RECALC,
(CALCS, RECALC)
UPDATE
STORE)
(CALCS,RECALC)
(CALCS, RECALC.EFFCMP)
(CALCS,RECALC)
(CALCS, RECALC,
(UPDATE,STORE;
(CALCS, RECALC
FIGURE 46
WRPDMS-SCHEMATIC DIAGRAM OF ON-LINE PROGRAMS
123
-------
PLANT= LONG BEACH WRP
MONTH =
197
FLOWS
TOTAL
PLANT
EFFLUENT DISCHARGE POINTS
AVERAGE
DAILY
PEAK
DAILY
TOTAL
RETURN
ACTIVATED
SLUDGE
WASTE
ACTIVATED
SLUDGE
PROCESS
AIR
NO. 001
COYOTE
CREEK
mgd
mg d
mgd
mgd
mcf/day
mgd
10
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
AVG.
DATE
REMARKS'
FIGURE 47
EXAMPLE OF RAW DATA
COLLECTION SHEETS
124
-------
PLANT'
LJ
H
O
1
2
3
4
5
SUSPENDED
RAW
SEWAGE
mg/l
10
PRIMARY
EFFL.
mg/l
1 1
SEC.
EFFL.
mg/l
12
FILTER
EFFL.
mg/l
13
/
/
/
/
/
FINAL
EFFLUENT
mg/l
14
Ibs/doy
•p^/!52£*
MONTH-
SOLIDS
197
REQUIREMENTS GOVERNING DISCHARGE TO •
NAVIGABLE WATERS 8 TRIBUTARIES
ARITHMETIC MEAN
OF PAST 30
CALENDAR DAYS DATA
FINAL
EFFLUENT
mg/l
$$"! 6'Xt
Ibs/day
>$£I7#>
PLANT
REMOV.
%
i-s-iie-s-;
THERETO
ARITHMETIC MEAN
OF PAST 7
CALENDAR DAYS
FINAL EFFLUENT
DATA
mg/l
X^XisXX^
Ibs/day
-JXX2 O'J'y'J
ALLOWABLE REUSES
ARITHMETIC MEAN
OF PAST 30
CALENDAR DAYS
FINAL EFFLUENT
DATA
mg/l
X'5<2ly9 •'.'/,
ALLOWABLE REUSES
ARITHMETIC MEAN
OF PAST 30
CALENDAR DAYS
FINAL EFFLUENT
DATA
mg/l
'//,40'///
Ibs/day
///4\'///
EXAMPLE OF RAW DATA COLLECTION SHEETS
(NOTE: ONLY TOP PORTION OF EACH SHEET IS SHOWN)
FIGURE 47 (CONTINUED)
125
-------
PLANT- MONTH' 197
UJ
<
Q
1
2
3
4
5
BACTERIA
CHLORINE CONTACT
CHAMBER EFFLUENT
DAILY GRAB SAMPLES
TOTAL
COL 1 FORM
MPN/IOO ml
42
FECAL
COLIFORM
MPN/IOOml
43
REQUIREMENTS GOVERNING DISCHARGE TO •
NAVIGABLE WATERS a TRIBUTARIES THERETO
GEOMETRIC MEAN OF
FECAL COLIFORM DATA
DURING PAST*
30 DAYS
MPN/IOO ml
>XXX>44j>>$<<^<
7 DAYS
MPN/IOOml
X^-^4 5^/^^-
MEDIAN OF
LAST 7
TOTAL COLIFORM
SAMPLES
MPN/IOOml
JS^xS^&S*-; 4 6 x^X&^P'x*
ALLOWABLE REUSES
MEDIAN OF
LAST 7
TOTAL COLIFORM
SAMPLES
MPN/IOO ml
>9S^SS(S55c4 7 J9999562
PLANT= MONTH' 197
Ld
H
<
Q
1
2
3
4
5
RESIDUAL CHLORINE
CHLORINE CONTACT
CHAMBER EFFLUENT
MINIMUM
DAILY
VALUE
mg/l
48
MAXIMUM
DAILY
VALUE
mg/l
49
DAILY GRAB
SAMPLES
CHLOR-
INATED
mg/l
50
DECHLOR-
INATED
mg/l
51
pH
FINAL
EFFLUENT
DAILY
GRAB
SAMPLE
52
OIL AND GREASE
FINAL
EFFLUENT
DAILY
GRAB
SAMPLE
mg/l
53
Ibs/day
6£554><5<5<$
ARITHMETIC MEAN
OF PAST 30
CALENDAR DAYS
EXCLUDING DAYS
OF REUSE
mg/l
5<55v555Jx5<
1 bs/day
>5«56Ji
Ibs/day
x/O'GSX/^
REUSE
DISCHARGE
mg/l
XX*67XX
Ibs/day
AERATION
SYSTEM
AMMONIA
OXID.
%
^X69^XX
EXAMPLE OF RAW DATA COLLECTION SHEETS
(NOTE' ONLY TOP PORTION OF EACH SHEET IS SHOWN)
FIGURE 47 (CONTINUED)
126
-------
PLANT' MONTH: 197
UJ
1-
<
Q
1
2
3
4
5
TURBIDITY
SECONDARY
EFFLUENT
TU
70
FILTER
EFFLUENT
TU
71
/
/
/
/
/
FINAL EFFLUENT
DAILY
24- HOUR
COMPOSITE
TU
72
CONTINUOUS READING
METER
MINIMUM
DAILY
VALUE
TU
73
MAXIMUM
DAI LY
VALUE
TU
74
SECCHI DISC
SECONDARY
EFFLUENT
feet
75
FILTER
EFFLUENT
feet
76
/
/
/
/
/
PLANT' MONTH^ 197
UJ
H
<
Q
1
2
3
4
5
SETTLEABLE SOLIDS
DAILY
24-HOUR
COMPOSITE
ml/1
77
PAST 30-DAY AVERAGE
NAVIGABLE
WATER
DISCHARGE
ml/I
'/?^w/7)
REUSE
DISCHARGE
ml/I
',:7A7 y,WA
TDS
DAILY
24- HOUR
COMPOSITE
180° C EVAP. TEMP.
mg/l
80
Ibs/day
w.eix^
SPECIF.
CONDUC.
DAILY
24-HOUR
COMPOSITE
^mho/cm
82
TEMP.
DAILY
GRAB
SAMPLE
°F
83
COLOR
SECONDARY
EFFLUENT
UNITS
84
FILTER
EFFLUENT
UNITS
85
/
/
/
/
PLANT- MONTH: 197
UJ
I-
<
Q
1
2
3
4
5
CHLORIDE
DAILY
24-HOUR
COMPOSITE
mg/l
86
Ibs/day
-V.'x87 .•'.''/
SULFATE
DAILY
24-HOUR
COMPOSITE
mg/l
88
Ibs/day
•vX-89 '•'/.
CHLORIDE PLUS
SULFATE
ARITHMETIC SUM
OF THE TWO
ANALYSES
mg/l
'•'//•30 •'•'''.'
Ibs/day
.•.;.-.'9|- '.'.'.
DETERGENTS
(MBAS)
DAILY
24-HOUR
COMPOSITE
mg/l
92
EXAMPLE OF RAW DATA COLLECTION SHEETS
(NOTE = ONLY TOP PORTION OF EACH SHEET IS SHOWN)
FIGURE 47 (CONTINUED)
127
-------
PLANT • MONTH= 197
LJ
1-
<
Q
1
2
3
4
5
MISCELLANEOUS
RETURN
SLUDGE
SUSPENDED
SOLIDS
mg/l
93
UNITS OUT OF SERVICE
PRIMARY
TANKS
94
AERATION
TANKS
95
Fl NALS
SYSTEM
NO. 1
96
FINALS
SYSTEM
NO. 2
97
FINALS
SYSTEM
NO. 3
98
FILTERS
99
/
/
/
/
/
100
101
102
103
PLANT= MONTH= 197
UJ
<
Q
1
2
3
4
5
AERATION SYSTEM NO. 1
SUSPENDED SOLIDS
24-HOUR COMPOSITES
TANK
1
mg/l
104
TANK
2
mg/l
105
TANK
3
mg/l
106
TANK
4
mg/l
107
RETURN
ACTIVATED
SLUDGE
FLOW
RATE
mgd
108
AERAT.
VOLUME
mg
109
MIXED
LIQUOR
DISSOLVED
OXYGEN
MAX.
mg/l
110
MIN.
mg/l
III
LOADING PATTERN
TANK
1
%
112
TANK
2
%
113
TANK
3
%
114
TANK
4
%
115
SVI GRAB SAMPLE
SETTL.
SOLIDS
ml/1
116
SUSP.
SOLIDS
mg/l
117
SVI
ml/g
118
VOL AT.
SOLIDS
%
119
N02
LOW
FLOW
GRAB
SAMPLE
mg/l
120
HIGH
FLOW
GRAB
SAMPLE
mg/l
121
N03
LOW
FLOW
GRAB
SAMPLE
mg/l
122
HIGH
FLOW
GRAB
SAMPLE
mg/l
123
M
00
EXAMPLE OF RAW DATA COLLECTION SHEETS
(NOTE: ONLY TOP PORTION OF EACH SHEET IS SHOWN)
FIGURE 47 (CONTINUED)
-------
plants that do not have solids handling processes. For the
District 26 Water Renovation Plant and the District 32 Water
Renovation Plant, which process solids by anaerobic digestion,
centrifugation and/or air flotation, additional data sheets are
utilized. Shown in Figure 48 are these data sheets.
Examination of Figure 47 shows that there are a maximum of 84
raw data columns on the sheets. Note, however, that not all are
presently used. Many have been crossed out because applicable
treatment process are not now in operation. However, within
several years, it is anticipated that all plants will have some
form of tertiary treatment involving filtration. The sheets
have been designed to handle additional data to be generated
when this additional treatment begins. The remaining 39 columns
on the sheets are reserved for inserting calculated values
generated by the computer.
As shown in Figure 48 there are a maximum of 54 columns of data
to handle the digestion and solids processing equipment at the
two applicable treatment plants. In actual practice, neither
treatment plant measures all parameters on a daily basis.
Data Entry
Because several of the data, e.g. BOD5 and coliform bacteria,
require several days of laboratory testing time before results
are available, whereas most other data are available within one
day, the WRPDMS is designed to accept both types of data when
they first become available. Obviously, a system user could
become easily confused as to which data have been entered and
which have not. To avoid this, the first transaction the treat-
ment plant operator should run each day is STATUS. Figure 49
shows a typical STATUS transaction. The data specified ON-LINE
refer to all data columns except those eight specifically listed
in the printout, and include all daily data for which results
are available on the day following the day in question. Those
specific data listed in the STATUS transaction either take more
129
-------
U)
o
PLANT' MONTH' 197
DATE
i
SOLIDS HAN -D LING
SLUDGE
RAW
FLOW
MGD
143
TOTAL
SOLIDS
%
144
VOLA-
TILE
SOLIDS
°/
145
WASTE ACTIVATED
FLOW
TO
CENTRI-
FUGE
MGD
146
FLOW
TO
A F
UNIT
MGD
147
TOTAL
SOLIDS
%
148
CENTRIFUGE
CENTRATE
FLOW
MGD
149
TOTAL
SOLIDS
%
150
CAKE
FLOW
MGD
151
TOTAL
SOLIDS
%
152
VOLA-
TILE
SOLIDS
01
153
TIME
IN
OPERA-
TION
hours
154
AIR FLOTATION UNIT
UNDERFLOW
FLOW
MGD
155
TOTAL
SOLIDS
%
156
CAKE
FLOW
MGD
157
TOTAL
SOLIDS
%
158
VOLA-
TILE
SOLIDS
%
159
TIME
IN
OPERA-
TION
hours
160
PLANT MONTH' 197
DATE
i
SOLIDS HANDLING
SMALL DIGESTION SYSTEM
PRIMARY DIGESTER
RAW
SLUDGE
FLOW
MGD
161
CENT.
DEWAT.
W.A.S.
FLOW
MGD
162
A.F.
DEWAT.
WAS
FLOW
MGD
163
pH
164
ALKA-
LINITY
mg/l
165
VOLA-
TILE
ACIDS
mg/ 1
166
TEMP
°F
167
EFF.
TOTAL
SOLIDS
%
168
EFF
VOLA-
TILE
SOLIDS
%
169
SECONDARY DIGESTER
RAW
SLUDGE
FLOW
MGD
170
CENT.
DEWAT.
W.A.S
FLOW
MGD
171
A F
DEWAT.
W.AS.
FLOW
MGD
172
pH
173
VOLA-
TILE
ACIDS
mg/l
174
SUPER-
NATANT
SOLIDS
% T S
175
HAULED
SLUDGE
FLOW
MGD
176
HAULED
SLUDGE
TOTAL
SOLIDS
%
177
HAULED
SLUDGE
VOLA-
TILE
SOLIDS
%
178
GAS
PRODUC-
TION
MCF
179
PLANT- MONTH' 197
DATE
i
SOLIDS HANDLING
LARGE DIGESTION SYSTEM
PRIMARY DIGESTER
RAW
SLUDGE
FLOW
MGD
ISO
CENT.
DEWAT
W.AS.
FLOW
MGD
181
A F.
DEWAT.
W.A.S.
FLOW
MGD
182
pH
183
ALKA-
LINITY
mg/l
184
VOLA-
TILE
ACIDS
mg/l
185
TEMP
°F
186
EFF.
TOTAL
SOLIDS
%
187
EFF
VOLA-
TILE
SOLIDS
%
188
SECONDARY DIGESTER
RAW
SLUDGE
FLOW
MGD
189
CENT.
DEWAT.
W.A.S.
FLOW
MGD
190
A.F.
DEWAT.
WAS.
FLOW
MGD
191
pH
192
VOLA-
TILE
ACIDS
mg/l
193
SUPER-
NATANT
SOLIDS
% T.S.
194
HAULED
SLUDGE
FLOW
MGD
195
HAULED
SLUDGE
TOTAL
SOLIDS
%
196
HAULED
SLUDGE
VOLA-
TILE
SOLIDS
%
197
GAS
PRODUC-
TION
MCF
198
RAW DATA
FIGURE 48
COLLECTION SHEETS USED FOR SOLIDS HANDLING UNIT PROCESSES
(NOTE'ONLY TOP PORTION OF EACH SHEET IS SHOWN)
-------
WRPDMS,STATUS
LACSD VHP DATA MANAGEMENT SYSTEM
FOR SYSTEM AVAILABILITY CALL: JAO (213) 699-7411 EXT. 499
STATUS FOR: LONG BEACH WRP
DATE: 6/24/75 TIME: 13/15
ON-LINE DATA : I/ 1/75 THROUGH 6/22/75
*** DATA *** LAST ENTERED
BOD 6/17
TOTAL COLI 6/21
FECAL COLI 6/21
NITROGEN 6/10
T D S 6/10
CHLORIDE 6/10
SULFATE 6/10
DETERGENTS 6/10
TRANSACTION COMPLETE
EXAMPLE OF PRINTOUT OF
A STATUS TRANSACTION
FIGURE 49
131
-------
than one day for analysis or are normally entered at less than a
daily frequency. From the STATUS transaction then, the operator
can determine his latest entries of data, and from this enter new
data in correct chronological sequence.
Having determined from the STATUS transaction his most recent en-
tries, the operator next determines if he has available data such
as BOD or bacterial data taken on days for which other data have
already been entered. If this is the case, he would use an UPDATE
transaction to enter the data. The UPDATE transaction will re-
trieve the already created data record for that day and insert the
data in the appropriate storage column. In addition, if the data
include bacterial, BOD5, total nitrogen, TDS, chloride, or sulfate
data, the appropriate calculations associated with these para-
meters will also be automatically calculated and stored. Figure
50 shows the results of a typical UPDATE transaction, in which
influent and effluent BOD- data and effluent total coliform and
fecal coliform data were entered.
After updating all necessary data records, the operator next
begins to enter those data for the day following the last day for
which data are stored. To do this, he has two transaction options
available to him: STORE and CALCS. The former will only store
data, while the latter will perform necessary calculations with
the data, and, if successful in this latter task, will store both
raw data and results of calculations. Figure 51 shows the results
of a typical STORE transaction.
If the data entry is achieved with the CALCS transaction, no fur-
ther steps are necessary. If, however, all new data are entered
with the STORE transaction, the operator next performs RECALC, the
transaction which simultaneously performs plant operational cal-
culations and effluent compliance calculations. Of course, if the
data are being entered with a CALCS transaction, these calcula-
tions would be automatically performed.
Plant Operational Calculations
The daily plant operational calculations can be divided into five
groups of calculations:
132
-------
WRPDMS,UPDATE,06/01/75
LACSD WRP DATA MANAGEMENT SYSTEM
FOR SYSTEM AVAILABILITY CALL: JAO (213) 699-7411 EXT.
BEGIN DATA ENTRY
/ 31,181
/ 33,6
/ 42,<2
/ 43,<2
/ EOD/
TRANSACTION COMPLETE-- DATA STORED
EXAMPLE OF PRINTOUT OF
AN UPDATE TRANSACTION
FIGURE 50
133
-------
WRPDMS,STORE,06/14/75
LACSD WRP DATA MANAGEMENT SYSTEM
FOR SYSTEM AVAILABILITY CALL: JAO (213) 699-7411 EXT. 499
BEGIN DATA ENTRY
/ 1,1.78
/ 2,2.35
/ 3, .8
/ 4,0
/ 5,6.62
/ 6,1.78
/ 10,344
/ 1 1, 172
/ 12,108
/ 14,13
/ 23,715
/ 24,484
/ 29,63
/ 30,46
/ 42,<2
/ 50,2.9
/ 52,7.1
/ 58,27
/ 60,14
/ 61,E
/ 62,E
/ 72,6.5
/ 75,2.5
/ 77,<.l
/ 83,78
/ 93,7638
/ 94,0
/ 95,0
/ 96,0
/ 104,5801
/ 105,2605
/ 104,5393
/ 105,2447
/ 106,1917
/ 108,.8
/ 109,.235
/ 110, 1 . 1
/ 1 11, . 1
/ 112,0
/ 113,100
/ 114,0
/ 116,350
/ 117,2658
/ 118,132
/ 119,83
/ 120,E
/ 121,E
/ 122,E
/ 123,E
/ 143,.0042
/ 144,3.23
/ 147,0
/ 160,0
/ 161,.0042
/ 163,0
/ 164,7.45
/ 165,3800
/ 166,20
/ 167,96
/ 170,0
/ 172,0
' 176,0
/ 177,0
/ 178,0
/ EOD/
TRANSACTION COMPLETE-- DATA STORED
FIGURE 51 TYPICAL STORE PRINTOUT
134
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Loading Calculations - Table 7 lists the formulas used in calcu-
lation of the following COD and Process Air Loading Parameters.
1. Total Mass of COD Applied to the Aeration System Per Day -
The units calculated are Ibs/day- To convert to the metric
units of kg/day multiply by 0.4536.
2. Total Mass of COD Applied Each Day to the Total Mass of Vola-
tile Suspended Solids in the Secondary Treatment System - The
Calculated units are Ibs COD/lb TPVSS/day. The metric units
of kg COD/kg TPVSS/day are identical.
3. Total Mass of COD Applied Each Day to the Mass of Volatile
Suspended Solids in the Mixed Liquor in the Secondary Treat-
ment System - The calculated units are Ibs COD/lbs MLVSS/day.
Again, metric units of kg COD/kg MLVSS/day are identical
numbers.
4. Cubic Feet of Air Applied per Gallon of Measured Flow Per Day -
To convert to the metric units of m3 of air/m3 of flow multi-
ply by 7.48.
5. Cubic Feet of Air Applied per Unit of Mass of COD Removed in
the Secondary Treatment System - The calculated units are
ft3/lb COD. To convert to the metric units of m3/kg COD
multiply by 0.0624.
Solids Calculations - Table 8 lists the formulas used in the cal-
culation of the following solids parameters:
1. Total Mass of Suspended Solids in the Aeration System - The
calculated units are Ibs. To convert to kg multiply by
0.4536.
2. Total Mass of Suspended Solids in the Mixed Liquor Portion of
the Aeration System - The Sanitation District's activated
sludge treatment plants employ the step-feed process, wherein
primary effluent is introduced at several points along the
aeration system. There i~s thus a continual variation in
suspended solids ranging from that of undiluted return
sludge at the upstream end of the aeration system, to complete
mixed liquor at the furthest downstream portion of the system.
135
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Table 7. LOADING CALCULATIONS FORMULAS
AERATION SYSTEM LOAD - (COD LOAD)
(ASL) = (PECODT)(Qp)(3.34)
where:
ASL = Aeration system load,
Ibs/day
PECODT = Primary effluent COD,
total, mg/1
= Total plant flow, mgd
P
8.34
= Ibs/M.G. per mg/1
TOTAL PLANT LOADING
(TPL)
where:
TPL
ASL
TPSS
PV
(ASL)
(TPSS)(PV)/(100,%)
Total plant loading,
Ibs COD/lb TPVSS/
day
Aeration system load,
Ibs/day
Total plant suspended
solids, Ibs
Percent volatile
suspended solids, %
MIXED LIQUOR LOADING
(MLL)
where:
MLL
ASL
MLSS
PV
(ASL)
(MLSS)(PV)/(100,
Mixed liquor loading,
Ibs COD/lb MLVSS/day
Aeration system load,
Ibs/day
Mixed liquor suspend-
ed solids, Ibs
Percent volatile sus-
pended solids, %
AIR RATE (AIR RATIO)
where:
(AR)
AR
Q,
P
Air rate, ft3/gal
Process air flow,
mcf/day
Total plant flow,
mgd
AIR RATE
where:
AR
^a
QP
PECOD
T
'
SECOD =
S
8.34
106
(PECODT-SECODS)(Q )(8.34)
Air rate, ft3/lb COD
removed
Process air flow, mcf/
day
Total plant flow, mgd
Primary effluent COD,
total, mg/1
Secondary effluent COD,
soluble, mg/1
Ibs/M.G. per mg/1
ft3/million ft3
136
-------
Table 8. SOLIDS CALCULATIONS FORMULAS
TOTAL AERATION SOLIDS
(SSl + SS2 + ...SSMT)(TAV)(8.34)
= - NT NT -
where:
TAS = Total aeration solids, Ibs
SS. = Suspended solids in tank or pass i, i=l to NT, mg/1
TAV = Total tank volume of aeration system, MG
NT = Number of tanks or passes in aeration system
8.34 = Ibs/MG per mg/1
MIXED LIQUOR SUSPENDED SOLIDS
(MLSS) = [(SSi)(TLxi-RSAL)/(TL)+(SSi+i+...SSNT)](AV)(8.34)
where:
and:
MLSS = Mixed liquor suspended solids, Ibs
SS = Suspended solids in tank or pass, mg/1
TL = Aeration tank length, ft
i = Tank or pass number in which centroid of loading
is located
RSAL = Return sludge aeration length, ft
NT = Total number of tanks or passes in aeration system
AV = Aeration tank volume, MG
RSAV = Return sludge aeration volume, MG
XS = Aeration tank cross-section area, ft2
8.34 = Ibs/MG per mg/1
7.48 = gallons/ft3
106 = gallons/M.G.
137
-------
Table 8 (continued). SOLIDS CALCULATIONS FORMULAS
SECONDARY EFFLUENT SUSPENDED SOLIDS MASS EMISSION RATE
(SESSMER) = (SESS)(Qp)(8.34)
where:
SESSMER = Secondary effluent suspended solids mass emission rate,
Ibs/day
SESS = Secondary effluent suspended solids, mg/1
Q = Total plant flow, mgd
8.34 - Ibs/M.G. per mg/1
TOTAL PLANT SUSPENDED SOLIDS
(TPSS) = (TAS)+(SSf)(VOLf)(8.34)
where:
TPSS = Total plant suspended solids, Ibs
TAS - Total aeration solids, Ibs
VOL.c - Volume of final sedimentation tanks in service, M.G.
8.34 = Ibs/M.G. per mg/1
SSr - Suspended solids concentration at end of final
aeration tank, mg/1
MASTED SUSPENDED SOLIDS
(WSS) = (RSSSMQ )(8.34)
w
where:
WSS = Wasted suspended solids, Ibs/day
RSSS = Return sludge suspended solids, mg/1
Qw = Total waste activated sludge flow, mgd
8.34 = Ibs/M.G. per mg/1
138
-------
Table 8 (continued). SOLIDS CALCULATIONS FORMULAS
DAILY NET GROWTH
where:
(DNG) = (TPSS)-(PTPSS)+(WSS)+(SESS)
DNG = Daily net growth, Ibs/day
TPSS = Total plant suspended solids, Ibs/day
PTPSS = Previous day's total plant suspended solids, Ibs/day
WSS = Wasted suspended solids, Ibs/day
SESS = Secondary effluent suspended solids, Ibs/day
AVERAGE NET GROWTH
where:
(ANG) =
ANG
AQ
w
ARSSS
A%
ASESS
ATAS
AV
ASSEF
AFNLS
FV
(AQJ(ARSS)+(AQp)(ASESS)
(ATAS)(AV)+(ASSEF)(AFNLS)(FV)
Average net growth, Ibs growth/lbs system solids/day
Average waste activated sludge flow, mgd
Average return sludge suspended solids, mg/1
Average total plant flow, mgd
Average secondary effluent suspended solids, mg/1
Average total aeration solids, mg/1
Aeration tank volume, M.G.
Average suspended solids effluent to finals, mg/1
Average number of finals in service
Final sedimentation tank volume, M.G.
139
-------
To classify the aeration into two components, return sludge
aeration and mixed liquor aeration, the concept of Centroid
of Loading is used. The centroid of loading is that hypothe-
tical point in the aeration system which, if all primary
effluent were introduced there, would be equivalent to the
step feed pattern used. The total mass of suspended solids
in the mixed liquor, then is calculated as those suspended
solids downstream of the centroid of loading. The calculated
units are Ibs. To convert to metric units of kg multiply by
0.4536.
3. Total Mass of Suspended Solids in the Entire Secondary Treatment
System Including Aeration Tanks and Final Clarifiers - This
parameter is called Total Plant Suspended Solids and the units
are Ibs. To convert to the metric units of kg multiply by
0.4536.
4. Total Mass of Activated Sludge Intentionally Wasted from the
Treatment System Each Day - The calculated units are Ibs/day.
To convert to kg/day multiply by 0.4536.
5. Total Mass of Suspended Solids Discharged Each Day in the
Treated Effluent - The calculated units are Ibs/day. To
convert to kg/day multiply by 0.4536.
6. Daily Net Growth - This calculation is a mass balance on the
suspended solids in the aeration system, and represents the
mass of suspended solids grown in the treatment system each
day. This calculation can yield a negative result. The cal-
culated units are Ibs/day. To convert to kg/day multiply by
0.4536.
7. Average Net Growth - The theory of biological reactors and
the equations derived therefrom in Section VIII are based on
the assumption that the biological reactor is in a steady
state of operation. In reality, however, this is many times
not the case. Thus, it is that from day to day there can be
significant changes in the Daily Net Growth and Daily Cell
Residence Time (to be discussed in the next section). To
overcome these short-term fluctuations, which disappear if
140
-------
data are averaged over a long period of time, the concept of
average net growth was developed. The average net growth is cal-
culated using the average of all necessary parameters over the
period of time equal to the previous days' cell residence time.
However, there are minimum and maximum time limits to this ave-
raging period of 7 and 15 days respectively. These are necessary
to insure that sufficient number of days of data are being ave-
raged to smooth out the fluctuations and, for the other limit,to
prevent the computer from averaging an excessive number of days
which would make the results meaningless and restrict other com-
puter usage for an excessive period of time. The units calculated
are pounds of growth per day per pound of system solids, or days <
Aeration Time Calculations - Table 9 lists the formulas used in
the calculation of the following aeration time parameters:
1. Return Sludge Hydraulic Aeration Time - This parameter is the
reaeration time the concentrated return sludge receives in
the aeration system upstream of any introduction of primary
effluent. It is calculated using the assumption that 20 feet
(6.1 meters) upstream of the first feed gate, the aeration
system is essentially undiluted return sludge. Note that for
all treatment plants it is not possible to calculate this
parameter, for the first feed gate is within 20 feet of the
furthest upstream end of the aeration system. The calculated
units are hours.
2. Mixed Liquor Hydraulic Aeration Time - This parameter is cal-
culated using the assumption that all primary effluent and all
return sludge are introduced at the most upstream end of the
aeration system. The calculated detention time is the maxi-
mum that could occur, for it assumes a plug flow reactor
whereas the step feed process simulates a series of complete
mix reactors. The calculated units are hours.
3. Return Sludge Centroidal Aeration Time - This parameter is
the aeration time upstream of the hypothetical point of
centroidal loading. The calculated units are hours.
141
-------
Table 9. AERATION TIME CALCULATIONS FORMULAS
RETURN SLUDGE AERATION TIME (HYDRAULICS)
where:
and:
(HRSAT) -
(HRSAV) =
HRSAT
HRSAV
RAS
XS
FG1
24
133700 =
(24)(HRSAV)
IRAS)
(XS)(FG1-20)
(133700)
Return sludge aeration time, hrs
Hydraulic return sludge aeration volume, M.G.
(if HRSAV <=0, HRSAT=0)
Return activated sludge flow, mgd
Aeration tank cross - section area, ft2
Distance from upstream end of aeration system to
first feed gate location, ft
hours/day
ft3/M.G.
MIXED LIQUOR AERATION TIME (HYDRAULIC)
(HMLAT) = - (HRSAV)
where:
HMLAT
(Qp)/NS + (RAS)
Mixed liquor aeration time, hrs
HRSAV
%
NS
RAS
24
Hydraulic return sludge aeration volume, M.G,
Total plant flow, mgd
Number of aeration systems in operation
Return activated sludge flow, mgd
hours/day
142
-------
Table 9 (continued). AERATION TIME CALCULATIONS FORMULAS
RETURN SLUDGE AERATION TIME (CENTROIDAL)
(CRSAT) = (RSAVM14I
where:
CRSAT = Return sludge aeration time, hrs
RSAV = Return sludge aeration volume, M.G.
Q = Return activated sludge flow, mgd
24 = hours/day
MIXED LIQUOR AERATION TIME (CENTROIDAL)
(TAV - RSAV) (24)
where:
CMLAT = Mixed liquor aeration time, hrs
TAV = Total tank volume of aeration system, M.G.
RSAV = Return sludge aeration volume, M.G.
Q = Total plant flow, mgd
Q = Return activated sludge flow, mgd
NS = Number of aeration systems in operation
24 = hours/day
143
-------
4. Mixed Liquor Centroidal Aeration Time - This parameter
is the aeration time downstream of the hypothetical
point of centroidal loading. The calculated units are
hours.
Cell Residence Time Calculations - Table 10 lists the for-
mulas used in the calculation of the following parameters:
1. Daily Cell Residence Time - As explained in Section VIII,
the mean cell residence time of a biological reactor at
steady state is calculated using the assumption that the
mass of organisms grown per day equals the sura of mass of
organisms intentionally wasted per day from the return
sludge line and those organisms unintentionally wasted
in the secondary effluent.
2. Average Cell Residence Time - This parameter is the
reciperocal of the Average Net Growth. As previously
explained, it represents the average of appropriate
data over a period of time ranging from 7 to 15 days.
3. Waste Activated Sludge Rate to Maintain Desired Cell
Residence Time Using Daily Data. - The formula used in
this calculation is derived from equation (3) of
Section VIII, using the assumption that the mass of
cells grown per day equals the solids discharged in
effluent and wasted from the return sludge line.
Obviously, with daily fluctuations in plant perfor-
mance, this particular waste rate may be inappropriate.
The calculated units are mgd. To convert to m3/day
multiply by 3785.
4. Waste Activated Sludge Rate to Maintain Desired Cell
Residence Time Using Average Data - This calculation is
based on the average of data over the same period used
144
-------
Table 10. CELL RESIDENCE TIME CALCULATIONS FORMULAS
AVERAGE CELL RESIDENCE TIME
(ACRT) = ^
where:
ACRT = Average cell residence time, days
ANG = Average net growth, Ibs growth/day/lb system solids
DAILY CELL RESIDENCE TIME
(DCRT)
(SESS)+(WSS)
where:
DCRT = Daily cell residence time, days
TPSS = Total plant suspended solids, Ibs
SESS = Secondary effluent suspended solids, Ibs/day
WSS = Wasted suspended solids, Ibs/day
145
-------
Table 10 (continued). CELL RESIDENCE TIME CALCULATIONS FORMULAS
DAILY WASTE RATE FOR DESIRED CRT
where:
(DWR)
DWR
TAS
AV
SSEF
FNLS
FV
DSCRT
%
SESS
RSSS
(TAS)(AV) + (SSEF) (FNLS) (FV)-(DSCRT) (Qp) (SESS)
(DSCRT)(RSS)
Daily waste rate, mgd
Total plant aeration solids, mg/1
Aeration tank volume, rug
Suspended solids effluent to finals, mg/1
Number of finals in service
Final sedimentation tank volume, mg
Desired cell residence time, days
Total plant flow, mgd
Secondary effluent suspended solids, mg/1
Return sludge suspended solids, mg/1
AVERAGE WASTE FLOW FOR DESIRED CRT
where:
(AWF)
AWF
ATAS
AV
ASSEF
AFNLS
FV
DSCRT
ASESS
ARSSS
(ATAS)(AV)+(ASSEF)(AFNLS)(FV)-(DSCRT)(AQ )(ASESS)
(DSCRT)(ARSSS)
Average waste flow for desired CRT, mgd
Average total aeration solids, mg/1
Aeration tank volume, mg
Average suspended solids effluent to finals, mg/1
Average number of finals in service
Final sedimentation tank volume, mg
Desired cell residence time, days
Average total plant flow, mgd
Average secondary effluent suspended solids, mg/1
Average return sludge suspended solids, mg/1
146
-------
to calculate the Average Cell Residence Time. This value
is less affected by short-term fluctuations and is,
therefore, a more appropriate waste sludge rate to use.
Obviously, if the biological treatment system has been
operating in a state of steady state for some time,
this calculation should agree closely with the one
derived from daily data only. The calculated units
are mgd. To convert to m3/day multiply by 3785.
Solids Handling Calculations
The District 26 Water Renovation Plant and the District 32
Water Renovation Plant both process solids, generated in the
primary and secondary treatment processes, by a combination
of thickening and anaerobic digestion. To better understand
the operational calculations used to monitor and control
these processes the following description of these processes
is presented.
Figure 52 presents a schematic flow diagram of the thickening
and digestion processes. Raw sludge from the hoppers of the
primary sedimentation tanks is of sufficient thickness to be
fed directly to the anaerobic digester. However, the waste
activated sludges require treatment to increase solids content
prior to digestion. At the District 26 Water Renovation Plant
centrifuges are used for this purpose, while at the District
32 Water Renovation Plant dissolved air flotation units are
utilized. The combination of the two sludges is fed into the
first of a series of two digesters. This first digester is
referred to as the primary digester and employs gas recircula-
tion to maintain a complete mix state. It is in the primary
digester where the major portion of the anaerobic stabilization
of the solids occurs. The effluent from the primary digester
flows into the second of the series of digesters, referred to
as the secondary digester. This latter digester is not mixed
or heated. Solids settle to the bottom, while the supernatant
147
-------
PRIMARY SLUDGE
WASTE ACTIVATED
SLUDGE
Thickening
Process
a:
UJ
o
LU
LU
r
LARGE DIGESTION SYSTEM
Primary
Digester
Secondary
Digester
SMALL DIGESTION SYSTEM
Primary
Dig ester
Secondary
Digester
I
RETURN TO AERATION SYSTEM
I
I
m
m
o
o
r~
o
HAULED BY TRUCK TO NEARBY DISPOSAL SITES
FIGURE 52 SCHEMATIC FLOW DIAGRAM OF THICKENING AND ANAEROBIC
DIGESTION PROCESS AT THE DISTRICT 26 & 32 WRPs
-------
is returned to the aeration system of the activated sludge
process. Daily monitoring of the solids content of this
latter supernatant is maintained. When supernatant solids
concentrations reach 0.5%, the solids which have settled
in the secondary digester are removed and trucked to nearby
farm land for tilling into the soil. Both the District 26
Water Renovation Plant and the District 32 Water Renovation
Plant have two of these digestion systems, each consisting
of the series of two digester tanks. The two systems at
each plant are referred to as "Small Digestion System" and
"Large Digestion System."
Several deviations from the above mentioned flow pattern can
be implemented. Each plant also has the capability to feed
primary sludge and/or thickened waste activated sludge directly
into the secondary digester.
The computer transaction which performs the Solids Handling
Calculations is called DIGEST. It can be executed as a
separate transaction, or provisions are available to make it
an extension of the CALCS or STORE/RECALC transactions.
Whichever method of execution is used, the process consists
of entering appropriate data and then performing pertinent
calculations. Table 11 lists the formulas used in these
calculations. Each is briefly discussed below.
1. Total Raw Sludge Flow - This is the total flow of sludge
put into the digesters each day. Note that under normal
operating conditions all raw sludge is fed into the primary
digester, and hence, the second term of the equation is
normally zero. The units are million of gallons per day.
To convert to cubic meters per day multiply by 3785.
2. Raw Solids Loading-Individual Digesters - This represents
the total mass of raw sludge, including volatile and inert
solids, loaded into either the primary or secondary
digester each day. The calculated units are Ibs/day. To
149
-------
convert to kg/day multiply by 0.4536.
3. Total Raw Solids Loading-All Digesters - This is the sum
of the individual loadings calculated above. The units
are identical as above.
4. Total Dewatered Waste Activated Sludge Flow - This is the
volume of thickened waste activated sludge fed to the
digesters each day. Again, under normal conditions, no
flow would go to the secondary digesters. The calculated
units are mgd. To convert to m3/day multiply by 3785.
5. Dewatered Waste Activated Sludge Solids Loading-Individual
Digester - This is the mass of total solids fed to either
the primary or secondary digester each day. The units are
Ibs/day. To convert to kg/day multiply by 0.4536.
6. Total Dewatered Waste Activated Sludge Solids Loading - This
is the sum of the above calculations made for both digesters
7. Centrifuge/Air Flotation Unit Solids Loading - This calcu-
lation gives the mass loading rate of the particular sludge
thickening process. The calculated units are Ibs/hour. To
convert to pounds per day multiply by 24. To convert to
kg/day multiply by 10.89- To convert to kg/hour multiply
by 0.4536.
8. Centrifuge/Air Flotation Unit Solids Recovery - This is
the percentage of the suspended solids in the unthickened
waste activated sludge which end up in the flow to the
digesters.
9. Primary Digester Volatile Solids Loading - This calculation
gives the mass of volatile solids loaded into the primary
digester per day per unit of volume of digester capacity.
As most of the digestion occurs only in the primary digester,
no similar calculation is made for the secondary digester.
The calculated units are pounds of volatile solids per' day
per cubic foot of digester volume. To convert to the
150
-------
Table 11. SOLIDS HANDLING CALCULATIONS
TOTAL RAW SLUDGE FLOW
where:
(TRSF)
TRSF
PDRSF
SDRSF
(RSRSF)+(SDRSF)
Total raw sludge flow, mgd
Primary digester raw sludge flow, mgd
Secondary digester raw sludge flow, mgd
RAW SOLIDS LOADING INVIDIVUAL DIGESTERS
where:
(RSL)
RSL
RSF
TS
8.34
(RSF)(TS)(8.34)(10l+)
Raw sludge loading, Ibs total solids/day
Raw sludge flow, mgd
Total solids content of raw sludge, %
Ibs/M.G./ppm
ppm/%
TOTAL RAW SOLIDS LOADING - ALL DIGESTERS
where:
(TRSL)
TRSL
PDRSL
SDRSL
(PDRSL)+(SDRSL)
Total raw solids loading, Ibs TS/day
Primary digester raw solids loading, Ibs TS/day
Secondary digester raw solids loading, Ibs TS/day
151
-------
Table 11 (continued). SOLIDS HANDLING CALCULATIONS
TOTAL DEWATERED WASTE ACTIVATED SLUDGE FLOW
(TDWASF) - (PDWASF)+(SDWASF)
where:
TDWASF = Total dewatered waste activated sludge flow, mgd
PDWASF = Primary digester waste activated sludge flow, mgd
SDWASF = Secondary digester waste activated sludge flow, mgd
DEWATERED WASTE ACTIVATED SLUDGE SOLIDS LOADING - INDIVIDUAL DIGESTER
(DWASSL) = (DWASF)(TS)(8.34)(101+)
where:
DWASSL = Dewatered waste activated sludge solids loading,
Ibs/day
DWASF = Dewatered waste activated flow, mgd
TS = Total solids, %
8.34 = Ibs/M.G./ppm
104 = ppm/%
152
-------
Table 11 (continued). SOLIDS HANDLING CALCULATIONS
TOTAL DEWATERED WASTE ACTIVATED SLUDGE SOLIDS LOADING
(TDWASSL) = (PDDWASSL)+(SDDWASSL)
where:
TDWASSL = Total dewatered waste activated sludge solids loading,
Ibs TS/day
TDDWASSL = Primary digester dewatered waste activated sludge
solids loading, Ibs TS/day
SDDWASSL = Secondary digester dewatered waste activated sludge
solids loading, Ibs TS/day
CENTRIFUGE/AIR FLOATATION UNIT SOLIDS LOADING
(CASL) - (WASF)(TS)(8 34)(10tt)
where:
CASL = Centrifuge/air floatation unit solids loading, Ibs/hr
WASF = Waste activated sludge flow, M.G.
TS = Total solids, waste activated sludge, %
TIO = Time in operation, hours
8.34 = Ibs/M.G./ppm
104 = ppm/%
153
-------
Table 11 (continued). SOLIDS HANDLING CALCULATIONS
CENTRIFUGE/AIR FLOATION UNIT SOLIDS RECOVERY
(CASR)
(CTS)[(NASTS)-(TS)](100.)
(WASTS)[(CTS)-(TS)J ""
where:
CASR
CTS
WASTS
TS
Centrifuge/air floation unit solids recovery,
Cake total solids content, %
Waste activated sludge total solids content, 5
Centrate or underflow total solids content, %
PRIMARY DIGESTER VOLATILE SOLIDS LOADING
(SL)
where:
SL
RSL
VS
DWASSL
PDV
1.34xl05
(RSL)(VS)+(DWASSL)(VS)
(PDV)(1.34xl05)
Solids loading, Ibs VS/day/ft3
Raw solids loading, Ibs TS/day
Corresponding volatile solids content, %
Dewatered waste activated sludge solids loading,
Ibs TS/day
Primary digester volume, M.G.
ft3/M.G.
154
-------
Table 11 (continued). SOLIDS HANDLING CALCULATIONS
HYDRAULIC DETENTION TIME (Primary Digester)
(PHDT)
where:
PHDT
PDV
PDRSF
PDWASF
(PDV)
(PDRSF)+(PDWASF)
= Primary digester hydraulic detention time, days
= Primary digester volume, M.G.
= Primary digester raw sludge flow, mgd
= Primary digester dewatered waste activated sludge
flow, mgd
VOLATILE SOLIDS DESTRUCTION
(VSD)
(VOLI)-(EVS)(10-2)
(VOLI)-(VOLI)(EVS)(10-2)
whPrP- (VOID - [(PDRSF)(RSPV)+(PDWASF)(UASPV)]10
wnere. \VULIJ - (PDRSF+WASF)
-2
and
VSD = Volatile solids destruction, %
VOLI = Volatile solids influent to digester, %
PDRSF = Primary digester raw sludge flow, mgd
RSPV = Raw sludge volatile content, %
PDWASF = Primary digester waste activated sludge flow, mgd
WASPV = Waste activated sludge volatile content, %
EVS = Primary digester effluent volatile content, %
10~2 = Conversion from percent to decimal
155
-------
Table 11 (continued). SOLIDS HANDLING CALCULATIONS
VOLATILE MATTER DESTROYED
(VMD)
(SL)(VSD)(1000)
- ~(ioo)
where:
VMD
SL
VSD
1000
100
= Volatile matter destroyed, Ibs VS/day/103ft3
= Solids loading, Ibs VS/day/ft3
= Volatile solids destruction, %
= Ft3/thousand ft3
= Conversion from %
GAS PRODUCTION
(GP)
where:
GP
GF
VMD
PDV
106
1000
1.34xl05
(GF)(106)(1000)
(VMD)(PDV)(1.34xl05)
Gas production, ft3/lb VMD
Gas flow, MCF
Volatile matter destroyed, Ibs VS/dayl03ft3
Primary digester volume, M.G.
ft3/MCF
ft3/thousand ft
ft3/M.G.
156
-------
Table 11 (continued). SOLIDS HANDLING CALCULATIONS
HYDRAULIC DETENTION TIME (Secondary Digester)
(SHOT)
where:
SHOT
SDV
PDRSF
PDWASF
SDRSF
SDWASF
(SDV)
(PDRSF)+(PDWASF)+(SDRS)+(SDWASF)
Secondary digester hydraulic detention time, days
Secondary digester volume, M.G.
Primary digester raw sludge flow, mgd
Primary digester waste activated sludge flow, mgd
Secondary digester raw sludge flow, mgd
Secondary digester dewatered waste, mgd
activated sludge flow, mgd
SOLIDS HAULED
(SH)
where:
SH
HSF
HSTS
8.34
(HSF)(HSTS)(8.34)(101+)
Solids hauled, Ibs/day
Hauled sludge flow, mgd
Hauled sludge total solids content,
Ibs/M.G./ppm
ppm/%
VOLATILE SOLIDS HAULED
(VSH)
where:
VSH
SH
HSVS
100
(SH)(HSVS)
(100)
Volatile solids hauled, Ibs/day
Solids hauled, Ibs/day
Hauled sludge volatile solids content,
Conversion from %
157
-------
metric units of kilograms of volatile solids per day per
cubic meter multiply by 16.02.
10. Hydraulic Detention Time in Primary Digester - This gives
the average detention time assuming a complete mix system.
The calculated units are days.
11. Volatile Solids Destruction - This gives the percentage of
volatile solids destroyed in the primary digester.
12. Volatile Matter Destroyed - This gives the mass of volatile
matter destroyed each day per thousand units of digester
volume. The units are pounds per day per 1,000 cubic feet.
To convert to the metric units of kilograms of volatile
solids per day per cubic meter multiply by 0.01602.
13. Gas Production in Primary Digester - This is the volume
of gas produced per unit mass of volatile matter destroyed.
The units are cubic feet per pound of volatile matter
destroyed. To convert to metric units of cubic meters
per kilogram of volatile solids destroyed multiply by
0.06243.
14. Hydraulic Detention Time in Secondary Digester - This
gives a theoretical average detention time in the
secondary digester assuming the unit is completely mixed
which it is not. The calculated units are days.
15. Solids Hauled from Plant - This represents the mass per
day of solids hauled by truck to the farm land for tilling.
The units are Ibs/day. To convert to kg/day multiply by
0.4536.
16. Volatile Solids Hauled from Plant - This is the mass of
volatile solids hauled from the plant each day. Again,
the units are Ibs/day. To convert to kg/day multiply by
0.4536.
Effluent Compliance Calculations
Each of the activated sludge treatment plants operated by the
158
-------
Sanitation Districts has two independent sets of effluent
discharge requirements established by the Regional Water Quality
Control Board, the state regulatory agency which establishes
and enforces discharge requirements in California. One set of
requirements at each plant governs the discharge into navigable
waters and tributaries thereto, and hence is regulated by dis-
charge criteria promulgated in PL92-500, the 1972 Amendments to
the Federal Water Pollution Control Act. These discharge re-
quirements are contained in the National Pollutant Discharge
Elimination System (NPDES) permit issued for each plant, and
are referred to in this report as NPDES requirements. The
other set of requirements for each plant are those issued by
the Regional Water Quality Control Board under criteria promul-
gated in the California Water Code to govern those discharges
of effluent which involve or result in a reuse of the effluent.
For this report these discharge requirements are referred to
as REUSE requirements and all calculations associated therewith
are referred to as REUSE calculations.
The calculations involved in the evaluation of compliance to
discharge requirements are part of the routine in the CALCS
and the RECALC transactions. There is a transaction which
will produce the report only. It is called EFFCMP (for EFFluent
CoMPliance). Shown in Figure 53 is the printout of a typical
EFFCMP report. Note that the calculations are divided into
three groups: those involving data specifically for the day
in question, those involving data averaged over the latest
7-day period, and those involving data averaged over the
latest 30-day period. Each is discussed below.
Daily Calculations - Table 12 lists the formulas used to
calculate these daily parameters. Note, however, in Figure
53, that the concentration data listed for the various para-
meters are input data, not calculated values. The mass emission
rates listed are based on the flow to either NPDES discharge or
to REUSE discharge and may not be based on total plant flow.
159
-------
WRPDMS/EFFCMP/05/01/75
LACSD WRP DATA MANAGEMENT SYSTEM
FOR SYSTEM AVAILABILITY CALL: JAO (213) 699-7411 EXT. 499
WQCB COMPLIANCE CALCS NOW IN PROGRESS
NO PLANT EFFLUENT COMPLIANCE VIOLATIONS
SAN JOSE CREEK VRP
DAILY VALUES
WQCB COMPLIANCE CALCULATIONS
NPDES REUSE
DATE: 5/ 1/75
NPDES REUSE
FLOW 05/01
MG **
SUSPENDED SOLIDS 05/01
2 CONC/ MG/L **
3 MER/ LBS/DAY
TDSO80 DEG) 05/01
6 CONC/ MG/L •*
7 MER/ KLBS/DAY *
OIL £ GREASE 05/01
10 CONC, MG/L
11 MER/ LBS/DAY
SULFATE
14 CONC> MG/L *
15 MER/ KLBS/DAY *
SETTLEABLE SOLIDS 05/01
18 CONC, ML/L
TURBIDITY
15.4 9.8 1 CONC/ TU
BODC 5-DAY)
994 CONG, MG/L »*
1156 739 5 MER/ LBS/DAY
TOTAL NITROGEN
654 654 8 CONC/ MG/L
54 9 MER/ LBS/DAY
CHLORIDE
< 1.0 12 CONC/ MG/L »
< 128 13 MER, KLBS/DAY
SULFATE+CHLORIDE
16 CONC/ MG/L *
17 MER/ KLBS/DAY
DETERGENTS
< . 1 < .1 19 CONC/ MG/L **
05/01
05/01
7-DAY VALUES
SUSPENDED SOLIDS 05/01
20 CONC/ MG/L
21 MER/ LBS/DAY
TOTAL COLIFORM 05/01
24 MEDIAN/ MPN/100 ML
30-DAY VALUES
SUSPENDED SOLIDS 05/01
26 CONC/ MG/L
27 MER, LBS/DAY
28 REMOVAL/ X
OIL* GREASE 05/01
32 CONC/ MG/L
33 MER/ LBS/DAY
SETTLEABLE SOLIDS 05/01
36 CONC/ ML/L
BOD(5-DAY)
10 22 CONC/ MG/L
1490 23 MER/ LBS/DAY
FECAL COLIFORM
2 2 25 G.M./ MPN/100
BODC5-DAY)
6 10 29 CONC/ MG/L
1063 873 30 MER/ LBS/DAY
98.5 31 REMOVAL/ %
TOTAL NITROGEN
: 1.1 34 CONC/ MG/L
= 204 35 MER/ LBS/DAY
FECAL COLIFORM
3.0
12
1541
05/01
9
1289
05/01
ML <
05/01
05/01
05/01
5
863
98.4
15.4
2729
3.0
12
985
9
830
37 G.M., MPN/100 ML
» NPDES VALUE APPLIES TO DISCHARGE TO UNLINED RIVERS ONLY
** NPDES VALUE HAS NO NPDES MAXIMUM LIMIT
PRINTOUT OF A TYPICAL EFFCMP TRANSACTION
FIGURE 53
160
-------
Table 12. EFFLUENT COMPLIANCE DAILY CALCULATIONS FORMULAS
DAILY MASS EMISSION RATES (Suspended Solids, BOD, Total Nitrogen, TDS,
Chloride, Sulfate, Chloride plus Sulfate
(MER) = (CONC)(DISCH)(8.34)
for CONC>0 & DISCH>0
where:
MER = Mass emission rate of particular parameter, Ibs/day
CONC = Concentration of particular parameter, mg/1
DISCH = NPDES discharge for 'navigable water & tributaries'
(NPDES) calculation, mgd
DISCH = REUSE discharge for 'allowable reuse' calculation,
mgd
8.34 = Ibs/M.G./mg/l
FINAL EFFLUENT OIL & GREASE MASS EMISSION RATE
(OGMER)
where:
OGMER
FEOG
NPDES
8.34
= (FEOG)(NPDES)(8.34)
for FEOG>0, NPDES>0
= Final effluent oil & grease mass emission rate,
Ibs/day
= Final effluent oil & grease concentration, mg/1
= NPDES discharge, mgd
= Ibs/M.G. per mg/1
161
-------
Table 12 (continued). EFFLUENT COMPLIANCE DAILY CALCULATIONS FORMULAS
FINAL EFFLUENT TOTAL NIIROGEN
(TN)
(ORG)+(NH3)+(N02)+(N03)
for ORG>0 & NH3>0 & N02>0 & N03>0
where:
TN = Final effluent total nitrogen (as N), mg/1
ORG = Final effluent organic nitrogen, mg/1
N03 = Final effluent NH3-N, mg/1
N02 = Final effluent N02-N, mg/1
N03 = Final effluent N03-N, mg/1
FINAL EFFLUENT TOTAL NITROGEN MASS EMISSION RATE
(TNMER) - (TN)(DISCH)(8.34)
for TN>0
where:
TNMER
TN
DISCH
DISCH
8.34
= Final effluent total nitrogen mass emission rate,
Ibs/day
= Final effluent total nitrogen concentration, mg/1
= NPDES discharge for 'navigable water & tributaries'
(NPDES) calculation, mgd
= REUSE discharge for 'allowable reuse' calculation,
mgd
= Ibs/M.G. per mg/1
162
-------
Seven Day Average Calculations - Table 13 lists those formulas
used in these calculations. The seven-day arithmetic and geo-
metric means are required for evaluation of NPDES discharge
only, not REUSE discharges. Thus, in Figure 53 these parti-
cular parameters are not listed in the REUSE column even though
there was REUSE flow for that day- The seven-day median total
coliform calculations are required for both types of discharge
and are thus shown in both columns.
Thirty Day Average Calculations - Table 14 lists the formulas
used in these calculations. Again, some of the parameters are
required for NPDES discharges only, and, hence, the results of
calculations are not listed in the REUSE column.
In addition to calculation of the above parameters, the results
are automatically compared to the discharge limits established
for each facility. Figure 54 illustrates these limits which
are stored in the computer for one of the treatment plants. A
similar list exists for the other six facilities. This printout
of limits is not included as part of the on-line printouts, but
is rather a part of the System Management Programs to be
discussed below. As an example of how the operator is informed
of violations of limits, the data for one of the treatment
plants were deliberately altered to cause all of these limits
to be exceeded. Figure 55 illustrates the message which pre-
ceeds every EFFCMP printout if there are violations of
effluent discharge standards. If there were no violations of
effluent discharge standards, this fact too would be printed
at the start of each EFFCMP printout.
Reports
Figure 56 illustrates the portion of the daily report trans-
mitted to the operator listing the summary of operational data.
The report which lists the effluent compliance calculations
was shown in Figure 53. Shown in Figure 57 is the additional
report obtained at the two facilities which have solids
163
-------
Table 13. EFFLUENT COMPLIANCE 7-DAY AVERAGE CALCULATIONS FORMULAS
FINAL EFFLUENT SUSPENDED SOLIDS 7 DAY-MEAN
(SS7)
where:
SS7
and:
[Z7(FESS
N
for FESS.>0 & NPDES.>0, N>2, NPDES7>0
= Final effluent suspended solids 7-day mean, mg/1
FESS. = Final effluent suspended solids for day i, mg/1
NPDES.J = NPDES discharge for day i, mgd
N = Number of days where FESSi 0 and NPDESi 0
NPDES7 = Most recent day in the seven day period
FINAL EFFLUENT SUSPENDED SOLIDS MASS EMISSION RATE 7^DAY MEAN
(SSMER7) =
[E7(FESSi)(NPDESi)(8.34)]
where:
FESSi
and:
for FESS^O & NPDES^O, N>2, NPDES7>0
SSMER7 = Final effluent suspended solids mass emission rate
7-day mean, Ibs/day
= Final effluent suspended solids for day i, mg/1
NPDESi = NPDES discharge for day i, mgd
N = Number of days where FESS^O and NPDES.>0
8.34 = Ibs/M.G. per mg/1
NPDES7 = Most recent day in the seven day period
164
-------
Table 13 (continued). EFFLUENT COMPLIANCE 7-DAY AVERAGE CALCULATIONS
FORMULAS
FECAL COLIFORM BACTERIA 7-DAY GEOMETRIC MEAN
(FCOLI7) = L
1 = 1
,1/N
where:
and:
NPDES
7
for FCOLI.^0 & NPDES^O, N>2, NPDES7>0
FCOLI7 = Fecal coliform bacteria 7-day geometric mean,
MPN/100 ml
FCOLI. = Fecal coliform bacteria count for day i, MPN/100 ml
NPDES1 = NPDES discharge for day i
N
= Number of days where FCOLI..>0 and NPDES^O
- Most recent day in the seven day period
TOTAL COLIFORM BACTERIA 7-DAY MEDIAN
(TCOLI7) -
where:
TCOLI7
DISCH
(TCQLIJ
for DISCH7>0
Total coliform bacteria 7-day median, MPN/100 ml
Fourth highest total coliform bacteria count after
the values of the last 7 days where DISCH>0
have been arranged in ascending order, MPN/100 ml
NPDES discharge for 'navigable water & tributaries'
calculation or REUSE discharge for 'allowable
reuse' calculation; day seven is the most recent
in the seven day period
165
-------
Table 13 (continued). EFFLUENT COMPLIANCE 7-DAY AVERAGE CALCULATIONS
FORMULAS
F"INAL EFFLUENT BOD,- 7-DAY MEAN
b
(BOD7)
where:
BOD7
N
and:
[E7(FEBODn.)]
1 = 1
N
for FEBOD->0 & NPDES^O, N>2, NPDES7>0
= Final effluent BOD5 7-day mean, mg/1
FEBOD. - Final effluent BOD for day i, mg/1
NPDES = NPDES discharge for day i, mgd
= Number of days where FEBOD.>0 and NPDES..>0
NPDES7 = Most recent day in the seven day period
FINAL EFFLUENT BOD MASS EMISSION RATE 7-DAY MEAN
(BODMER7) =
where:
[Z7(FEBOD.)(NPDES1)(8.34)]
for FEBOD^O & NPDES. >0, N>2, NPDES7>0
and:
BODMER7 = Final effluent BOD mass emission rate 7-day mean;
Ibs/day
FEBODi = Final effluent BOD for day i, mg/1
NPDESn- - NPDES discharge for day i, mgd
N = Number of days where FEBOD.>0 and NPDES.>0
8.34 = Ibs/M.G. per mg/1
NPDES7 = Most recent day in the seven day period
166
-------
Table 14. EFFLUENT COMPLIANCE 30-DAY AVERAGE CALCULATION FORMULAS
FINAL EFFLUENT SUSPENDED SOLIDS 30-DAY MEAN
(SS30) =
where:
SS30
FESS.
DISCHi
N
and:
DISCHi
DISCH.
DISCH30
FINAL EFFLUENT
30
[E (FESS.)J
i = l
N
for FESS..>0 & DISCH.>0, N>3, DISCH30>0
= Final effluent suspended solids 30-day mean, mg/1
= Final effluent suspended solids for day i, mg/1
= Discharge for day i
= Number of days where FESS^O, and DISCH^O
= NPDES discharge for 'navigable waters & tributaries1
calculation
= REUSE discharge for 'allowable reuse' calculation
= Most recent day in the 30-day period
SUSPENDED SOLIDS MASS EMISSION RATE 30-DAY MEAN
30
(SSMER30) =
[E (FESS.)(DISCH )(8.34)]
for FESS^O & DISCH^O, N>3, DISCH30>0
where:
SSMER30
FESS
DISCHi
N
8.34
and:
DISCHi
DISCHi
DISCH30
= Final effluent suspended solids mass emission rate
30-day mean, Ibs/day
= Final effluent suspended solids, mg/1
= Discharge for day i, mgd
= Number of days where FESS^O and DISCH^O
= Ibs/M.G. per mg/1
= NPDES discharge for 'navigable water & tributaries'
= REUSE discharge for 'allowable reuse' calculation
= Most recent day in the 30-day period
167
-------
Table 14 (continued). EFFLUENT COMPLIANCE 30-DAY AVERAGE CALCULATION
FORMULA
FINAL EFFLUENT BOD 30-DAY MEAN
[fVEBOD^]
(BOD30) = 1=1 M
where:
BOD30
FEBODi
for FEBOD.>0 & DISCH.>0, N>3, DISCH30>0
= Final effluent BOD 30-day mean, mg/1
= Final effluent BOD for day i, mg/1
DISCH.J = Discharge for day i
and:
= Number of days where FEBOD^O and DISChK>0
DISCH.J = NPDES discharge for 'navigable waters & tributaries
DISCH- = REUSE discharge for 'allowable reuse' calculation
DISCH
30
= Most recent day in the 30-day period
FINAL EFFLUENT BOD MASS EMISSION RATE 30-DAY MEAN
30
(FEBOD.)(DISCH.)(8.34)]
(BODMER30)=
for FEBOD^O & DISCH^O, N>3, DISCH30>0
where:
and:
BODMER30 = Final effluent BOD mass emission rate 30-day mean,
Ibs/day
FEBOD. = Final effluent BOD for day i, mg/1
DISCH. = Discharge for day i, mgd
N = Number of days where FEBOD^O and DISCH.>0
8.34 = Ibs/M.G. per mg/1
DISCH. - NPDES discharge for 'navigable water & tributaries'
1 calculation
DISCH.J = REUSE discharge for 'allowable reuse' calculation
DISCH30 = Most recent day in the 30-day period
168
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Table 14 (continued). EFFLUENT COMPLIANCE 30-DAY AVERAGE CALCULATION
FORMULAS
SUSPENDED SOLIDS PLANT REMOVAL 30-DAY MEAN
(SSR30)
where:
SSR30
RSSSi
FESS.
NPDES.
Nl
N2
30 30
[(E (RSS.))/N1-(Z (FESS.))/N2)](100)
i=i 1=1
——-—$v • •———
(E (RSS.))/N1
for RSSS.>0, FESS.>0, NPDES.>0, Nl>3 & N2>3, NPDES30>0
= Suspended solids plant removal 30-day mean, %
- Raw sewage suspended solids for day i, mg/1
= Final effluent suspended solids for day i, mg/1
= NPDES discharge for day i, mgd
= Number of days where RSSS.>0
= Number of days where FESS.>0
and:
NPDES30 = Most recent day in the 30-day period
BODC PLANT REMOVAL 30-DAY MEAN
o
(BODR30)
where:
BODR30
RSBODi
FEBOD.
NPDESi
Nl
N2
30 30
[(E (RSBOD.))/NT-(E (FEBOD1))/N2](100)
(E (RSBOD.))/N1
1 = 1 ""
for RSBOD^O, FEBOD^O, NPDES.>0, Nl>3 & N2>3,
NPDES30>0
= BODr plant removal 30-day mean, %
= Raw sewage BOD for day i, mg/1
= Final effluent BOD for day i, mg/1
= NPDES discharge for day i, mgd
= Number of days where RSBOD^O
= Number of days where FEBOD.>0
and
NPDES30 = Most recent day in the 30-day period
169
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Table 14 (continued). EFFLUENT COMPLIANCE 30-DAY AVERAGE CALCULATION
FORMULAS
FECAL COLIFORM BACTERIA 30-DAY GEOMETRIC MEAN
To N 1/N
(FCOLI30) = [n (FCOLI.)]
1 = 1
for FCOLI. >0 & NPDES. >0, N>3, NPDES30>0
where:
FCOLI 30 = Fecal col i form bacteria 30-day geometric mean, MPN/
100 ml
FCOLI. = Fecal coliform bacteria count for day i, MPN/100 ml
NPDES. = NPDES discharge for day i
N = Number of days where FCOLI. >0 and NPDES.. >0
and:
NPDES30 = Most recent day in the 30-day period
SETTLEABLE SOLIDS 30-DAY MEAN
(STS30)
[f (STS.)]
for STS.>0 & DISCH.>0, N>3, DISCH30>0
where:
STS30 = Settleable solids 30-day mean, ml/1
STS. = Settleable solids for day i, ml/1
DISCH. - Discharge for day i
N - Number of days where STS.>0 and DISCH>>0
and:
DISCH30 = Most recent day in the 30-day period
170
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Table 14 (continued). EFFLUENT COMPLIANCE 30-DAY AVERAGE CALCULATION
FORMULAS
FINAL EFFLUENT TOTAL NITROGEN 30-DAY MEAN
(TN30)
where:
TN30
TN.
DISCH.
N
and:
DISCH..
DISCHi
DISCH30
FINAL EFFLUENT
30
Z (TN.)]
1 = 1
for TN1 >0 & DISCH.. >0, N>3, DISCH30>0
- Final effluent total nitrogen 30-day mean, mg/1
= Final effluent total nitrogen for day i, mg/1
= Discharge for day i
- Number of days where TN->0 and DISCH. >0
= NPDES discharge for 'navigable waters & tributaries'
= REUSE discharge for 'allowable reuse' calculation
= Most recent day in the 30-day period
TOTAL NITROGEN MASS EMISSION RATE 30-DAY MEAN
30
(TNMER30) =
[Z (TN.)(DISCH,)(8.34)]
i = i n
for TN.>0 & DISCH^O, N>3, DISCH30>0
where:
TNMER30
TNi
DISCH1
and
8.34
DISCH.
DISCH.
DISCH
30
= Final effluent total nitrogen mass emission rate 30-
day mean, Ibs/day
= Final effluent total nitrogen for day i, mg/1
= Discharge for day i, mgd
= Number of days where TN.>0 and DISCH.>0
- Ibs/M.G. per mg/1
= NPDES discharge for 'navigable waters & tributaries'
calculation
= REUSE discharge for 'allowable reuse' calculation
= Most recent day in the 30-day period
171
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Table 14 (continued). EFFLUENT COMPLIANCE 30-DAY AVERAGE CALCULATION
FORMULAS
FINAL EFFLUENT OIL & GREASE 30-DAY MEAN
(OG30)
where:
OG30
FEOGi
NPDES
N
and:
NPDES30
FINAL EFFLUENT
30
(I (FEOG.))
for FE06.>0 & NPDES.. >0, N>3, NPDES30>0
= Final effluent oil & grease 30-day mean, mg/1
= Final effluent oil & grease for day i, mg/1
= NPDES discharge for day i
= Number of days where FEOG.>0 and NPDES.. >0
= Most recent day in the 30-day period
OIL & GREASE MASS EMISSION RATE 30-DAY MEAN
(OGMER30) =
where:
OGMER30
FEOG.
NPDESi
N
8.34
and:
30
(I (FEOG.)(NPDES.)(8.34))
for FE06->0 & NPDES^O, N>3, NPDES30>0
NPDES
30
= Final effluent oil & grease mass emission rate 30-day
mean, Ibs/day
= Final effluent oil & grease for day i, mg/1
= NPDES discharge for day i, mgd
= Number of days where FEOG^O and NPDES.. >0
= Ibs/M.G. per mg/1
= Most recent day in the 30-day period
172
-------
WRP DATA MANAGEMENT SYSTEM
FILE MAINTENANCE PROGRAM
PLANT: (ONG_6FACH_WATER_PENQVATION_PLANT
FUNCTION: PRINT
RFCDFD KEY: P0700010
DATE: 06/02/75
TYPE: WQCB_LIMIT_RECORD
NPDES
TEM NO.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
?4
25
26
27
?8
29
30
31
32
33
34-
35
36
37
MA XI MUM
10.
10000.
4170.
10000.
3128.
10000.
10000.
10000.
10000.
15.
1564.
10000.
10000.
10000.
10000.
10000.
10000.
0.
10000.
40.
4170.
30.
3128.
10000.
400.
15.
1564.
100.
20.
2085.
100.
10.
1043.
10000.
10000.
0.
200.
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
200
000
000
000
000
000
000
000
000
000
000
oco
000
000
000
000
000
000
100
000
MI M MUM
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0,000
0.000
0.000
85.000
0.000
0.000
85.000
0.000
0.000
0.000
0.000
0.000
0.000
REUSE
ITEM NO.
1
2
3
4
5
6
7
3
9
12
13
14
15
16
17
18
19
24
26
27
29
30
34
35
36
MAXIMUM MINIMUM
10.000
40.000
4170.000
30.000
3128.000
1000.000
104.300
40.000
4170.000
250.000
26.060
10000.000
10000.000
500.000
52.130
0.200
10000.000
23.000
15.000
1564.000
'0.000
2085.000
30.000
3128.000
0. 100
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
NOTE: Values of 10,000 (for maximum limits) and 0 (for minimum
limits) denote the fact that no limit exists at this time;
however, such limits may be prescribed in the future.
EXAMPLE OF STORED EFFLUENT
FIGURE 54 COMPLIANCE LIMITS
173
-------
V'RPDMS, EFFCMP, 02/28/75
LACSD WRP DATA MANAGEMENT SYSTEM
FOR SYSTEM AVAILABILITY CALL. JAO (£13) 699-7411 EXT.
WQCB COMPLIANCE CALCS NOW IN PROGRESS
•'•PLANT EFFLUENT COMPLIANCE VI OLATI 0,\'S« »*
NPDLS:
DATE
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
ITEM
1
3
5
10
1 1
!8
20
21
22
23
25
26
27
28
29
30
31
32
33
36
37
VALUE
10. 1
5066. 7
38 15.7
15.1
1889. 1
0.3
40.5
4171.0
30.5
3 128. 5
401 . 0
16.0
1565.0
84. 0
21.0
2086.0
84.0
10.1
1 044, 0
0.2
201.0
LIMIT
10.0
4170.0
3128.0
1,5.0
1 564. 0
0.2
40.0
4170.0
30.0
3 128.0
400. 0
15.0
1564. 0
85.0
20. 0
2085.0
85.0
10.0
1043.0
0. 1
200.0
REUSE:
DATE
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
2/28
ITEM
1
2
3
4
5
6
7
8
9
12
13
16
17
18
24
26
27
29
30
34
35
36
VALUE
10.1
40.5
5066.7
30. 5
38 1 5. 7
1000. 5
125.0
41.0
5129. 1
250. 5
31.0
500.5
63.0
0.3
24.0
.15.5
1564.5
20. 5
2085.5
31.0
3129.0
0.2
LIMIT
10.0
40.0
4170.0
30. 0
3128.0
1000.0
104.3
40. 0
4170.0
250. 0
26. 1
500.0
52. 1
0.2
23.0
15.0
1 564. 0
20. 0
2085. 0
30. 0
3128.0
0. 1
NOTE: Stored data were intentionally altered to cause
every limit to be exceeded.
INITIAL PORTION OF EFFCMP PRINTOUT
WHEN EFFLUENT COMPLIANCE VIOLATIONS OCCUR
FIGURE 55
174
-------
LONG BEACH WRP
WQCB COMPLIANCE CALCULATIONS
DATE: 2/28/75
NPDES REUSE
DAILY VALUES
FLOW 02/28
MG *•
SUSPENDED SOLIDS 02/28
2 CONC, MG/L »*
3 MER, LBS/DAY
TDSC180 DEC) 02/28
6 CONC, MG/L **
7 HER, KLBS/DAY *
OIL A GREASE 02/28
10 CONC, MG/L
11 MER, LBS/DAY
SULFATE 02/28
14 CONC, MG/L *
15 HER, KLBS/DAY *
SETTLEABLE SOLIDS 02/28
18 CONC, ML/L
7-DAY VALUES
SUSPENDED SOLIDS 02/28
20 CONC, MG/L
21 MER, LBS/DAY
TOTAL COLIFORM 02/28
24 MEDIAN, MPN/100 ML
30-DAY VALUES
15.0 15.0
41
5067
1001
15. 1
1889
250
41
4171
SUSPENDED SOLIDS 02/28
26 CONC, MG/L
27 MER, LBS/DAY
28 REMOVAL/ %
0IL £ GREASE 02/28
32 CONC, MG/L
33 MER, LBS/DAY
SETTLEABLE SOLIDS 02/28
36 CONC, ML/L
16
1565
84.0
10. 1
1044
.2
41
5067
1001
125
250
31
24
16
1565
NPDES REUSE
TURBIDITY 02/28
1 CONC, TU 10.1 10.1
BODC5-DAY) 02/28
4 CONC, MG/L ** 31
5 MER, LBS/DAY 3816
TOTAL NITROGEN 02/28
8 CONC, MG/L 41.0
9 MER, LBS/DAY 5129
CHLORIDE 02/28
12 CONC, MG/L * 251
13 MER, KLBS/DAY •
SULFATE+CHLORIDE 02/28
16 CONC, MG/L * 501
17 MER, KLBS/DAY *
DETERGENTS 02/28
19 CONC, MG/L »* < .1
31
3816
41.0
5129
251
31
501
63
BODC5-DAY) 02/28
22 CONC, MG/L 31
23 MER, LBS/DAY 3129
FECAL COLIFORM 02/28
25 G.M., MPN/100 ML 401
BODC5-DAY) 02/28
29 CONC, MG/L 21
30 MER, LBS/DAY 2086
31 REMOVAL, % 84.0
TOTAL NITROGEN 02/28
34 CONC, MG/L
35 MER, LBS/DAY
FECAL COLIFORM 02/28
37 G.M., MPN/100 ML 201
21
2086
31.0
3129
* NPDES VALUE APPLIES TO DISCHARGE TO UNLINED RIVERS ONLY
** NPDES VALUE HAS NO NPDES MAXIMUM LIMIT
TRANSACTION COMPLETE
REMAINING PORTION OF EFFCMP PRINTOUT
FIGURE 55 (CONTINUED)
175
-------
LONG BEACH WRP
DATE: 5/28/75
FLOWS (MGD)
TOTAL PLANT 7.9
RETURN SLUDGE 3.52
WASTE ACTIVATED SLUDGE .123
SUSPENDED SOLIDS (MG/L)
PRIMARY EFFLUENT 120
FINAL EFFLUENT 5.0
RETURN SLUDGE 4200
PROCESS AIR
TOTAL (MSCF/DAY) 27.3
RATIO (SCF/GAL) 3.5
SCF/LB COD REMOVED 1412
TOTAL MLSS (LBS) 34200
SLUDGE VOLUME INDEX (ML/GM)
AERATION SOLIDS (LBS)
CENTROIDAL
MIXED LIQUOR AERATION (MRS)
RETURN SLUDGE AERATION (MRS)
HYDRAULIC (V/Q+R)
MIXED LIQUOR AERATION CHRS)
RETURN SLUDGE AERATION (MRS)
OPERATION PARAMETERS
DATE
24
25
26
27
28
TAS(LBS)
52300
52000
51600
54100
49500
COD/TPVSS
.385
.396
.424
.446
.442
SOLIDS MASS BALANCE
COD (MG/L)
PRIMARY EFFLUENT TOTAL 323
FINAL EFF. TOT/SOLUBLE 38/ 30
REMOVAL <% TOTAL) 91
AERATION SYSTEM LOAD
(LBS TOTAL COD/DAY) 21300
NITROGEN (MG/L)
PRIMARY EFF. NH3-N 23.8
FINAL EFF. NH3-N •1
N03-N 18.0
N02-N
YESTERDAY'S FINAL EFF. TDS
VOLATILE CONTENT (%) 83
UNIT-1 UNIT-2 UNIT-3 TOTAL AVERAGE
168 168
49500 49500
5. 1
4. 1
6.4
5. 1
4. 1
6.4
COD/MLVSS CENT MLAT(HRS) CRT(DAYS)
DATE
24
25
26
27
28
TPSS(LBS) WASTED (LBS)
61500
61500
60400
63200
58000
6337
4419
3916
4067
4294
.653
.665
.719
.753
.750
SESS (LBS)
197
237
493
473
330
5. 10
5.47
4.85
4.99
5.09
9.41
13.21
13.70
13.92
12.54
DAILY NET GROWTH(LBS)
5534
4656
3309
7340
-575
AVERAGE CRT (DAYS) 11.1
AVERAGE NET GROWTH (LBS SOLIDS/LBS SYS SOLIDS/DAY)
.090
CALCULATED WASTE RATES (MGD)
FOR AVERAGE 7 DAY CRT
FOR DAILY 7 DAY CRT
.23
. 19
EXAMPLE OF PRINTOUT OF DAILY OPERATIONAL
FIGURE 56 DATA AND CALCULATIONS
176
-------
DISTRICT 26 WRP
WRP/SOLIDS HANDLING
DATE: 5/ i/75
RAW SLUDGE
DIGESTER FLOW (MGD)
LARGE
PRIMARY .0080
LARGE
SECONDARY
SMALL
PRIMARY .0018
SMALL
SECONDARY
TOTALS
OPERATING PARAMETERS
DEWAT WAS
FLOW (MGD) RAW
CENT. /A. F. (LB
.0042
.0620
LARGE SMALL
PRIMARY PRIMARY
LOADING
TS/DAY)
3740
840
LARGE
WAS LOADING
(LB TS/DAY)
CENT. /A. F.
1930
28440
SMALL
SECONDARY SECONDARY
CRT (DAYS)
LOADING (LB VS/DAY/CF)
VOLATILE DESTRUCTION (%)
UNIT DESTRUCTION
(LB VS/DAY/1000 CF)
TOTAL GAS PRODUCTION
(MCF/DAY)
UNIT GAS PRODUCTION
(CF/LB VS DESTROYED)
VOLATILE ACIDS (MG/L)
SLUDGE DEWATERING
LOADING (LB/HR)
SOLIDS RECOVERY (
SLUDGE HAULING
.028
23.000
.010
26.000
CENTRIFUGE
178.0000
51 .0000
LARGE SYSTEM
HAULED SLUDGE FLOW (MGD)
TOTAL SOLIDS HAULED (LB/DAY)
VOLATILE SOLIDS HAULED (LB/DAY)
AIR FLOTATION
UNIT
SMALL SYSTEM
.0200
6000.0000
4700.0000
EXAMPLE OF PRINTOUT OF
SOLIDS HANDLING DATA AND CALCULATIONS
FIGURE 57
177
-------
handling equipment.
Shown in Appendix A is the monthly report listing all opera-
tional and discharge compliance data and calculations.
There is an additional transaction, LIST, which prints out for
any particular specified day the raw data and calculations
stored for that day. This transaction is useful for determining
the source of error if calculations cannot be successfully
performed using the stored data.
System Management Programs
Date Record Management Program - Shown in Figure 58 are those
parameters for which required entries are needed. That is, the
effluent discharge permits specify the frequency of analyses
of numerous parameters. This program then maintains a file
on most recent entry of each of the parameters. Also, the
program directs the off-line portion of the WRPDMS to perform
necessary 30-day statistical calculations.
Parameter Record Management Program - Shown in Figure 59 are
typical stored operational data needed to calculate daily
operational parameters.
Lower and Upper Limit Management Program - A program is avail-
able to establish upper and/or lower limits for all columns of
data and calculated results. Entry of any value lying outside
these limits will cause a message to be transmitted to the
operators that the data are abnormal. At the present time
this program is not in use. When normal operational ranges
for all parameters have been established, these limits will be
utilized to signal abnormal operation.
Required Data Record Management Program - This program operates
in conjunction with the Data Record Management Program to keep
track of when data are required. Thus, if a parameter is
specified to be monitored on a weekly basis, this program
checks if data are entered within the appropriate time. If
not, a message is sent to the operator informing him of
178
-------
WRP DATA MANAGE KENT SYSTEM
FILE MAINTENANCE PROGRAM
PLANT: WHITTIER_NARROWS_WATER_RECLAMATION_PLANT DATE: 06/02/75
TYPE: DATE_RECORD
FUNCTION: PPINT
RECORD KEY: P0200001
DATE WRP DATE
1. FIRST RECORD 8/ 1/74 2039
2. LAST RECORD 5/31/75 2342
3. BOD ENTRY 5/25/75 2336
4. TOTAL CDLIFORM ENTRY 5/26/75 2337
5. FECAL COLIFORM ENTRY 5/26/75 2337
6. NITROGEN ENTRY 5/20/75 2331
7. T D S ENTRY 5/20/75 2331
8. CHLORIDE ENTRY 5/20/75 2331
9. SULFATF ENTRY 5/20/75 2331
10. DETERGENT ENTRY 5/20/75 2331
II. OIL 6 GREASE ENTRY 5/31/75 2342
12. SULFATE+CHLCRIOE ENTRY 5/20/75 2331
13. SUSPENDED SOLIDS ENTRY 5/31/75 2342
14. SETFLEABLE SOLIDS ENTRY 5/31/75 2342
15. BOD CALC 5/25/75 2336
16. TOTAL COLIFOPM CALC 3/27/75 2277
17. FECAL COLIFORM CALC 5/26/75 2337
18. NITROGEN CALC 5/20/75 2331
19. T D S CALC 5/20/75 2311
20. CHLORIDE CALC 5/20/75 2331
21. SULFATE CALC 5/20/75 2331
22. OIL £ GREASE CALC 5/31/75 2342
23. SULFATF+CHLCRIDE CALC 5/20/75 2331
24. SUSPENDED SOLIDS CALC 5/31/75 2342
25. SETTLEABLE SOLIDS CALC 5/31/75 2342
26. OPERATION DAILY PRINTOUT 5/31/75 2342
NOTE: WRP Date is a chronological date numbering system that
arbitrarily begins with day 0001 on January 1, 1969.
DATE RECORD MANAGEMENT PROGRAM -
FIGURE 58 TYPICAL PRINTOUT
179
-------
WRP DATA MANAGEMENT SYSTEM
FILE MAINTENANCE PROGRAM
PLANT: wHITTIER_NARRUWS_WATER_RECLAMATION_PLANT DATE: 06/02/75
FUNCTION: PRINT TYPF: PARAMETER_RECORD
RECORD KEY: P0200002
1. PLANT IDENTIFICATION NUf-'RER.
2. NUMBER OF DATA POINTS
3. NUMBER OF AERATION SYSTEMS 1
4. NUMBER OF TANKS PER SYSTEM 3
5. AERATION TANK LENGTH, FT. 300
6. AERATION TANK VOLUME, MG 1.000
7. AERATION TANK CROSS-SECTIONAL APFA, SO. FT. 450
8. NUMBER OF FINAL SED. TANKS (TOTAL PLANT) 5
9. FINAL SEDIMENTATION TANK VOLUME PER SYSTEMf MG 1.122
10. NUMBER OF DISCHARGE POINTS
-------
of the lacking data.
EXPERIENCES USING THE WRPDMS
The on-line computer system is available for use seven hours
per day, five days per week. The actual amount of time the
treatment plant operator spends at the teletype terminal can
vary considerably depending upon his typing speed and number
of typing errors committed. The WRPDMS has program logic
which requires that transaction instructions be typed in an
exact specific order. Failure to do so elicits diagnostic
error messages from the computer with instructions to repeat
the attempted transaction. Personnel who have had sufficient
training on the system to know what to do without referring
to printed instructions and whose typing speed averages no
more than 20-30 words per minute have routinely demonstrated
that one day of data can be entered and calculations performed
in approximately 20 minutes. However, at the other extreme,
personnel with little or no typing ability and a general lack
of understanding of the system have spent over three hours
accomplishing the same task.
Calculation of statistical averages for monitoring reports has
required approximately 24 man-hours per plant per month
utilizing a desk top calculator. With the WRPDMS, this man-
power requirement has essentially been reduced to zero.
FUTURE MODIFICATIONS
Anticipated future modifications to the WRPDMS include utiliz-
ing the upper and lower limits to signal possible abnormal
trends, to develop statistical predictive equations which can
signal possible effluent compliance violations if recent
trends in data occur, and putting printouts of data and
calculations in a form suitable for direct submittal in
monthly monitoring reports.
181
-------
00
to
SAN JOSE CREEK HATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER S. GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
1*
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
TOTAL
FLOWS
TOTAL PLANT
AVERAGE
DAILY
INFLUENT
MGD
1
27.28
28.49
21.68
21.59
22.08
22.43
24.35
21.14
21.87
22.70
22.69
22.39
21 .55
21.76
21.89
21.10
21.58
21.33
20.99
20.90
21.22
19.97
20.80
20.63
21.74
21.95
22.01
21.81
22.14
619.92
PEAK
DAILY
INFLUENT
MGD
2
46.0
42.0
32.0
30.0
30.0
29. 0
28.0
30.0
31.0
31.0
32.0
32.0
31.0
30.0
31.0
32.0
38.0
30.0
31.0
31.0
32.0
31.0
32.0
30.0
30.0
31.0
31.0
31.0
32.0
TOTAL
RETURN
ACTIVATED
SLUDGE
MGD
3
7.16
7.25
6.95
6.59
7.71
6.84
6.44
6.51
6 • 6b
6.54
5.89
6.27
5.86
5.72
6.13
6.11
6.17
6^7
6.05
5.95
6.03
5.40
6.16
6.11
6.24
6.44
6.31
6.03
6.35
WASTE
ACTIVATED
SLUDGE
MGD
4
.011
.008
.072
.248
.315
.306
.297
.331
.359
.335
.282
.257
.326
.367
.213
. 100
.113
.098
.238
.417
.461
.338
.325
.271
.294
.396
.448
.655
.281
PROCESS
AIR
MCF/DAY
5
55.20
54.22
42.36
42.40
45.90
45.34
45.02
41.95
43.53
43.63
43.67
43.33
42.31
42.47
46.01
41.76
43. 74
43.11
42.32
41.87
40.47
38.54
39.92
42.60
43.94
45.23
44. 18
43.19
43.86
EFFLUENT DISCHARGE POINTS
NO. 001
SAN
GABRIEL
RIVER
MGD
6
27.3
28.5
21.7
21.6
22.1
22.4
24.3
21.1
21.9
22.7
22.7
22.4
21.5
21.8
21.9
21.1
21.6
21.3
21.0
20.9
21.2
20.0
20.8
20.6
21.7
21.9
22.0
21.8
22.1
619.9
NO. 002
SAN
JOSE
CREEK
MGD
7
.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
SPREADING
GROUNDS
MGD
8
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.000
9
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFF1C1ENT SAMPLE VOLUME, 0-HOLI DAY NO ANALYSIS, E-INSUFFICIENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX
-------
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER L GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
SUSPENDED SOLIDS
SEWAGE
MG/L
10
322
234
378
408
432
434
352
282
304
414
322
440
578
412
290
254
244
430
376
426
254
304
340
584
528
496
488
400
383
EFFL.
MG/L
11
146
116
100
116
116
104
106
112
10B
136
122
140
114
90
98
90
108
114
132
104
112
140
124
162
166
146
124
72
119
EFFL.
MG/L
12
EFFL.
MG/L
13
EFFLUENT
MG/L
14
54
65
12
7
10
9
8
10
10
8
3
6
7
7
Q
4
9
8
8
g
4
3
5
7
5
4
11
LBS/DAY
15
12286
15444
2170
1260
1841
1497
1828
1410
1459
1893
1892
1494
1438
1089
1278
1232
1440
712
1576
1394
1416
1332
694
1376
1088
1281
1101
728
2273
REQUIREMENTS GOVERNING DISCHARGE TO:
NAVIGABLE WATERS t TRIBUTARIES THERETO
ARITHMETIC MEAN
OF PAST 30
CALENDAR DAYS DATA
(- I N A L
EFFLUENT
MG/L
16
13
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
14
15
14
14
14
14
14
14
13
15
LbS/DAY
17
3014
3498
3539
3511
3487
3479
3475
3431
3447
3462
3469
3452
3435
3438
3411
3351
3339
3260
3200
3170
3169
3096
3062
3059
2999
2928
2887
2831
3282
PLANT
REMOV.
%
18
96
95
95
95
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
ARITHMETIC MEAN
OF PAST 7
CALENDAR DAYS
DATA
MG/L
19
27
35
34
34
33
30
24
17
9
9
g
9
g
6
6
8
3
7
7
7
7
7
7
7
7
7
7
6
14
L8S/DAY
20
6364
8160
7983
7830
7748
6796
5182
3636
1638
1598
1689
1639
1631
1525
1506
1474
1409
1241
1252
1246
1293
1300
1223
1214
1268
1228
1184
1086
2905
ALLOWABLE REUSES
ARITHMETIC MEAN
OF PAST 30
CALENDAR DAYS
DATA
MG/L
21
LBS/OAY
22
oo
CO
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-1NSUFF1C IENT SAMPLE VOLUME, 0-HOL1DAY NO ANALYSIS, E-INSUFF1C IENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
00
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER C GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
CHEMICAL OXYGEN DEMAND (COD)
RAW
SEWAGE
TOTAL
MG/L
23
460
716
629
961
967
659
983
517
402
530
846
619
641
494
596
400
749
615
1,022
1,155
663
462
571
575
659
571
630
584
667
PRIMARY
EFFLUENT
TOTAL
HG/L
24
290
255
269
312
356
273
375
268
230
292
343
278
313
319
261
222
255
331
350
347
327
290
264
345
338
308
300
311
301
SECONDARY
EFFLUENT
TOTAL
MG/L
25
SOLUBLE
MG/L
26
FILTER
EFFLUENT
TOTAL
MG/L
27
SOLUBLE
MG/L
28
FINAL
EFFLUENT
TOTAL
MG/L
29
115
100
31
41
36
49
47
42
37
38
31
33
33
40
31
29
31
36
38
33
35
33
33
22
35
29
28
30
40
SOLUBLE
MG/L
30
34
36
18
20
29
38
34
29
30
24
24
22
28
31
22
22
22
31
27
29
27
24
22
20
27
18
22
24
26
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFFIC1ENT SAMPLE VOLUME, D-HOLIDAY NO ANALYSIS, E-INSUPF 1CIENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK HATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN 0. PARKHURST - CHIEF ENGINEER & GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
?
3
4
5
6
7
8
9
10
11
12
13
1*
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
5-DAY BIOCHEMICAL OXYGEN DEMAND (BOD)
RAH
SEWAGE
MG/L
31
333
308
291
388
488
435
455
420
347
280
497
450
460
513
428
320
385
475
438
358
397
292
357
435
658
780
410
288
417
PRIMARY
EFFLUENT
MG/L
32
FINAL
EFFLUENT
MG/L
33
> 22
> 12
7
10
9
Q
7
> 12
> 12
6
6
7
6
y
i^
P
7
5
^
> 12
> 12
5
5
8
LBS/DAY
34
> 5,005
> 2,851
1,266
1,801
1,657
1,497
1,422
> 2,116
> 2,189
1,325
1,135
1,120
1,438
1,270
1,278
1,056
1,260
712
1,220
885
666
> 2,082
> 2,065
907
1,098
918
909
> 1,524
REQUIREMENTS GOVERNING DISCHARGE TO:
NAVIGABLE WATERS t TRIBUTARIES THERETO
ARITHMETIC MEAN
OF PAST 30
CALENDAR DAYS DATA
FINAL
EFFLUENT
MG/L
35
7
7
8
8
8
Q
8
8
8
a
3
3
8
8
8
8
9
8
8
8
8
8
8
9
9
8
8
8
8
LBS/DAY
36
1,729
1,801
1 ,797
1,802
1,789
1,797
1,804
1,833
1 ,866
1,870
1,867
1,829
1,829
1,813
1,803
1,805
1,832
1,784
1,774
1,755
1,744
1,688
1,692
1 ,730
1,679
1,658
1,653
1,627
1,773
PLANT
REMOV.
*
37
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
ARITHMETIC MEAN
OF PAST 7
CALENDAR DAYS
DATA
MG/L
38
> 11
> 11
> 11
> 12
> 12
> 12
> 11
> 9
> 9
> 9
> 9
> 8
> 8
> 8
> 8
7
7
6
7
6
6
6
> 7
> 7
> 7
> 7
> 7
> 7
} 8
LBS/UAY
39
> 2,552
> 2,617
> 2,554
> 2,660
> 2,658
> 2,471
> 2,214
> 1,801
> 1,707
> 1,715
> 1,620
> 1,543
> 1,535
> 1,513
> 1,394
1 ,232
1,222
1 , 162
1 ,169
1, 133
1,069
967
> 1,137
> 1,272
> 1,304
> 1,275
> 1,232
> 1,235
> 1,642
ALLOWABLE REUSES
ARITHMETIC MEAN
OF PAST 30
CALENDAR DAYS
DATA
MG/L
40
LBS/DAY
41
CD
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFFICIENT SAMPLE VOLUME, D-HOLIDAY NO ANALYSIS, E-INSUFF1C IENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN 0. PARKHURST - CHIEF ENGINEER £ GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEDIAN
BACTERIA
CHLORINE CONTACT
DAILY GRAB SAMPLES
TOTAL
MPN/100 ML
42
< 2
< 2
172
> 2400
< 2
4,
< 2
< 2
< 2
< 2
5
Q
^
< 2
< 2
< 2
< 2
2
< 2
5
8
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
FECAL
MPN/100 ML
43
< 2
< 2
8
175
<. 2
4
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
REQUIREMENTS GOVERNING DISCHARGE TO:
NAVIGABLE WATERS £ TRIBUTARIES
GEOMETRIC MEAN OF
FECAL COLIFORM DATA
DURING PAST
30 DAYS
MPN/100 ML
44
< 2
< 2
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< 3
< J
< 3
7 DAYS
MPN/100 ML
45
< 2
< 2
< 3
< 5
< 5
< 6
< 6
< 6
< 6
< 5
< 3
< 3
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
< 2
MEDIAN OF
LAST 7
TOTAL
SAMPLES
MPN/100 ML
46
< 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
< 2
< 2
ALLOWABLE
MEDIAN OF
LAST 7
TOTAL
SAMPLES
MPN/100 ML
47
A-SA.MPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFFICIENT SAMPLE VOLUME, O-HOLIDAY NO ANALYSIS, E-INSUFFICIENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK HATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER £ GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
q
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
RESIDUAL CHLORINE
CHLORINE CONTACT
CHAMBER EFFLUENT
MINIMUM
DAILY
VALUE
MG/L
48
Q
.3
.2
« 9
1.4
1 .6
1.4
4.9
4.2
3.8
5.6
4.7
4.1
.2
4.5
5.3
* o
4.4
.2
.2
5.2
5.6
5.2
7.8
5.1
.3
2 .2
3.8
3.0
MAXIMUM
DAILY
VALUE
MG/L
49
> 10. 0
> 10.0
8.6
7.3
> 10.0
> 10.0
> 10.0
> 10.0
> 10.0
9.8
7.4
7.6
7.6
> 10. 0
> 10.0
> 10.0
9.5
9.6
> 10.0
> 10. 0
> 10.0
> 10.0
> 10.0
> 10. 0
> 10.0
> 10.0
7.8
6.5
> 9.3
DAILY GRAB
SAMPLES
CHLOR-
INATED
MG/L
50
3.6
2.2
8.1
. 7
8.0
10.4
12,0
3.0
3.5
4.0
4. a
4. 7
3.4
4.4
5.7
8.4
5.2
3.8
10.8
7.0
4.7
11.3
12.6
9.5
15.2
22.0
7,2
4.8
7.2
DECHLOR-
INATED
MG/L
51
PH
FINAL
EFFLUENT
n A 1 1 v
UA 1 L T
GRAB
SAMPLE
52
6.60
6.70
6.70
6.70
6.60
6.70
6.80
7.00
6.90
6.80
6.90
6.90
6.90
7.00
6.90
6.70
6. 70
6.80
6.80
6.80
6.90
6.70
6.60
6.60
6.80
6.90
7.00
7.00
6.80
OIL AND GREASE
FINAL EFFLUENT
DAILY GKA8 SAMPLE
CONCEN-
TRATION
MG/L
53
< 1.0
< 5.7
< 1.0
1.2
1.1
< 1.0
< 1.0
< 1.0
< 1.0
< 1.0
1. 1
< 1.0
1.7
< 1.0
1.3
2. 1
< 1.0
< 1.0
< 1.0
1.7
< 1.0
< 1.0
< 1.0
1.9
< 1,0
< 1.0
< 1.0
< 1.0
< 1.3
NAVIGABLE
HATER
DISCHARGE
L8S/DAY
54
< 22d
1,354
< 181
216
203
< 187
< 203
< 176
< 182
< 189
208
< 187
306
< 181
237
370
< 180
< 178
< 175
296
< 177
< 167
< 173
327
< 181
< 183
< 184
< 182
< 250
ARITHMETIC MEAN OF
PAST 30 CALENDAR
DAYS DATA USING ONL
DAYS NAVIGABLE HATE
DISCHARGE OCCURRED
MG/L
55
< 1.3
< 1.5
< 1.5
< 1.5
< 1.5
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.4
< 1.3
< 1.4
IBS/DAY
56
< 312
< 350
< 3*8
< 347
< 346
< 335
< 322
< 320
< 318
< 311
< 310
< 308
< 310
< 308
< 307
< 308
< 303
< 301
< 298
< 300
< 298
< 281
< 279
< 282
< 280
< 269
< 268
< 250
< 306
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFF1CIENT SAMPLE VOLUME, 0-HOLIOAY NO ANALYSIS, E-INSUFF 1C IENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER & GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
NI TROG&N
24-HOUR FLOW COMPOSITE SAMPLES
PRIMARY
EF FL UE NT
ORGANIC
MG/L
57
NH3
MG/L
58
25.8
24. 1
19.6
24.9
25.2
18.5
27.4
24.6
25.2
26.6
30.2
28.8
25.2
25.2
24.6
25.2
23.8
2b.2
24.6
23.8
18.5
21.8
23.8
26.6
23.8
24.6
25.8
26.0
24.6
FINAL EFFLUENT
ORGANIC
MG/L
59
1.7
2.0
1.9
1. 1
1.7
NH3
MG/L
60
2.8
3.9
< .1
.9
2.7
4.1
4.9
6.0
4.1
5.6
11.2
9.8
9.4
12.6
7.8
2.1
4.9
8.3
11.9
12.2
13.3
12.2
12.9
12.9
11.8
12.3
13.3
12.9
< 3.1
N02
MG/L
61
.020
.030
.010
.010
.030
E
.010
.030
.030
.040
p
.060
. 060
.080
.080
E
.020
.080
.020
.020
.050
.070
.030
.030
.040
.080
.050
.050
.041
N03
MG/L
62
21.3
26.0
22.0
15.5
17.0
E
9.5
10.0
22.0
11. 1
E
8.0
10.1
3.8
11.5
E
18.0
5.9
2.8
1.6
1.5
2.5
9.0
4.2
2.7
3.5
1.8
6.4
9.4
TOTAL N
MG/L
63
18.1
18.7
16.2
15.6
17.2
LBS/OAY
64
3261
3548
2878
2836
3131
ARITHMETIC MEAN OF PAST
•2/-1 <~ A 1 P Mfl A P l~l A V C
D\J lyALCPJUAK UATj
TOTAL NITROGEN DATA
NlAWlPAAI f- U A T PG
("lAvlOAOl-C MAI t K
DISCHARGE
MG/L
65
19.4
19.4
19.4
19.2
19.2
19.6
19.6
19.6
19.6
19.4
19.4
18.9
18.9
18.9
18.9
18.9
18.9
18.4
lb.4
18.4
17.6
17.6
17.6
17.6
17.2
17.2
17.2
17.2
18.6
LBS/DAY
66
4642
4642
4642
4366
4366
4369
4369
4369
4369
•4204
4204
3915
3915
3915
3915
3915
3915
3708
3708
3708
3334
3334
3334
3334
3235
3235
3131
3131
3901
D p I ICC
n. t U JL
DISCHARGE
MG/L
67
LBS/DAY
68
A cp ATI HNI
A C t\ A 1 1 U IN
SYSTEM
A MMflKJ T A
A nnuni i A
n w f n
U A JL U *
%
69
89. 1
83.8
> 99.5
96.4
89.3
77.8
82.1
75.6
83.7
78.9
62.9
66.0
62.7
50.0
68.3
91.7
79.4
67.1
51.6
48.7
28. I
44.0
45.8
51.5
50.4
50.0
48.4
50.4
> 66.9
00
00
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFFICIENT SAMPLE VOLUME, D-HOL1DAY NO ANALYSIS, E-INSUFFICIENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER £ GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
2?
23
24
25
26
27
28
MEAN
TURBIDITY
SECONDARY
EFFLUENT
TU
70
FILTER
EFFLUENT
TU
71
FINAL EFFLUENT
DAILY
24-HOUR
COMPOSITE
TU
72
42.0
37.0
40.0
6.0
4.0
6.0
2.5
3.5
4.0
5.5
3.0
3.0
3.0
1.6
3.0
2.5
3.0
2.5
3.0
3.0
3.0
3.0
2.5
2.5
2.5
2.5
2.0
2.0
7.1
CONTINUOUS READING
MtTER
MINIMUM
DAILY
VALUE
TU
73
8.0
8.0
7.0
7.0
7.0
5.0
4.0
4.0
3.6
4.0
6.0
3.2
3.2
3.2
2.7
2.6
2.8
2.8
2.6
2.9
3.0
2.9
2.8
2.6
2.8
2.5
2.6
2.4
4.0
MAXIMUM
DAILY
VALUE
TU
74
80.0
98.0
21.0
10.0
8.0
13.0
9.0
5.8
6.1
6.0
6.0
3.6
3.4
3.6
3.8
3.6
3.3
3.2
3.7
3.4
3.4
3.4
3.6
4.6
3.4
4.0
3.5
3.0
11.5
SECCHI DISC
EFFLUENT
FEET
75
6.0
2.5
3.5
4.5
3.5
4.0
4.0
3.0
3.5
3.5
3.5
4.0
4.b
4.5
4.0
4.0
5.0
4.0
4.5
5.0
4.5
3.5
4.0
4.0
5.0
5.0
5.0
4.5
4.2
EFFLUENT
FEET
76
A-SAMPLER MALFUNCTION, 8-ANALYTICAL EKROR, C-lNSUFF1C IENT SAMPLE VOLUME, D-HOLIDAY NO ANALYSIS, E-1NSUFF1CIENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN 0. PARKHURST - CHIEF ENGINEER E. GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
SETTLEA8LE SOLIDS
24-HOUR
COMPOSITE
ML/L
77
4.5
3.5
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< . 1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .1
< .4
PAST 30-DAY AVERAGE
NAVIGABLE
WATER
DISCHARGE
ML/L
78
< .4
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
< .5
REUSE
DISCHARGE
ML/L
79
T D S
DAILY
COMPOSITE
180 DEC C
TEST
MG/L
80
700
569
554
640
650
682
718
615
544
564
621
700
560
667
596
570
587
614
591
661
655
598
553
569
622
656
664
647
620
DISCHARGE
RIVERS
AND/OR
TO REUSE
LBS/DAY
81
SPECIF.
24-HOUR
COMPOSITE
UMHO/CM
82
1,100
Ii050
975
1,075
1,075
1 ,195
1,230
1,190
1,070
1,075
It 175
1,130
1,160
1,175
1,175
1,000
1,025
1,085
1.210
1,075
1,262
1,175
1,100
1,125
1,260
1,230
1,240
1,112
1,134
TEMP.
GRAB
SAMPLE
0£G. F
83
72
72
72
72
72
71
71
70
71
71
72
71
72
72
70
72
72
72
73
73
70
71
72
72
72
72
73
72
COLCR
EFFLUENT
UNITS
84
EFFLUENT
UNITS
85
A-SAMPLER MALFUNCTION, B-ANALVTICAL ERROR, C-INSUFFICIENT SAMPLE VOLUME, 0-HOLIDAY NO ANALYSIS, E-INSUFf 1C IENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER (. GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
CHLORI DE
DAILY
24-HOUR
COMPOSITE
MG/L
86
135
123
131
15*
136
DISCHARGE
TO UNLINED
RIVERS
AND/OR
TO REUSE
LBS/DAY
87
SULFATE
DAILY
24-HOUR
COMPOSITE
MG/L
88
78
85
90
104
89
DISCHARGE
TO UNLINED
RIVERS
AND/OR
TO REUSE
LBS/DAY
89
CHLORIDE PLUS
SULFATE
DAILY
24-HOUR
COMPOSITE
MG/L
90
213.0
208.0
221.0
258.0
225.0
DISCHARGE
TO UNLINEO
RIVERS
A NO /OR
TO REUSE
LBS/DAY
91
DETERGENT
(MBAS)
UAILY
24-HOUR
COMPOSITE
MG/L
92
. 1
. I
.1
.2
.1
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR,
F-ON-LINE INSTRUMENT OUT OF SERVICE
C-INSUFFIC IENT SAMPLE VOLUME, D-HOLIDAY NO ANALYSIS, E-INSUFFICI t'NT MANPOWER
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LCS ANGELES COUNTY, CALIF.
JOHN 0. PARKHURST - CHIEF ENGINEER £. GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
RETURN
SLUDGE
SUSPENDED
SOLIDS
MG/L
93
6,202
7,464
6,602
6,789
6,220
6,838
6,406
6, 165
5,784
5 ,426
6,493
5,902
5,644
4,724
5,170
5 ,456
6,574
7,233
7,611
7,559
6,534
6,530
5,878
6,383
6,305
6,305
5,889
5,603
6,275
PRIMARY
TANKS
94
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
U N I
AERATION
TANKS
95
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
o
0
0
0
0
0
0
0
0
0
0
0
0
r s OUT
FINALS
SYSTEM
NO. 1
96
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
M I S C E L
OF S E R
: FINALS
SYSTEM
NO. 2
97
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
L A N E 0
VICE
FINAL
SYSTEM
NO. 3
98
1
1
1
I
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
J S
FILTERS
99
100
101
102
103
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFFICIENT SAMPLE VOLUME, D-HOLIDAY NO ANALYSIS, E-INSUFF1CIENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
CO
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER I GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
1 1
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
AERATION SYSTEM NO. I
SUSPENDED SOLIDS
24-HOUR COMPOSITES
PASS
1
MG/L
104
2997
3036
3283
3053
3038
3160
3329
3145
3087
2951
2960
2113
3349
2864
2959
2899
2805
3089
3045
3121
3210
3088
3269
3317
3407
3176
3204
2633
3057
PASS
2
MG/L
105
1673
1744
2188
2252
1942
2187
2055
2012
1940
1782
2116
1875
1895
2128
1794
1895
2023
2100
2027
2154
2007
1772
1796
1880
1909
1857
1943
1641
1950
PASS
3
MG/L
106
1411
1562
1606
1557
1602
1535
1797
1639
1638
1634
1751
1712
1785
1652
1517
1502
1515
1604
1576
1576
1612
1486
1618
1593
1652
1615
1532
1497
1599
PASS
4
MG/L
107
1228
1355
1538
1701
1673
1551
1806
1660
1639
1385
1421
1590
1465
868
1600
1457
1463
1553
1667
1598
1705
1491
1549
1469
1559
1529
1507
1315
1515
RETURN
ACTIVATED
SLUDGE
FLOW
RATE
MGD
108
2.29
2.33
2.08
2.19
2.57
2.28
2.18
2. 14
2.08
2.01
1.98
1.94
1.84
1.67
1.89
1.85
1.97
2.01
1.92
1.85
1.87
1.74
1.91
2.03
1.92
2.03
1.94
1.89
2.01
AERAT.
VOLUME
MG
109
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1,093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
U093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
MIXED
LIQUOR
DISSOLVED
MAX.
MG/L
110
HIM.
MG/L
111
A-SAMPLER MALFUNCTION, 8-ANALYTICAL ERROR, C-INSUFF1C IENT SAMPLE VOLUME, D-HOLIDAY NO ANALYSIS, E-1NSUFF1CIENT MANPOWER
F-ON-L1NE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN 0. PARKHURST - CHIEF ENGINEER £ GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
1*
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
AERATION SYSTEM NO. I
LOADING PATTERN
PASS
1
%
112
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
PASS
2
%
113
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
PASS
3
%
114
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
PASS
4
%
115
.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
SVI GRAB SAMPLE
SETTL.
SOLIDS
ML/L
116
245
220
225
225
230
220
200
190
210
200
200
190
200
200
200
235
240
240
250
250
290
300
345
350
350
380
425
390
257
SUSP.
SOLIDS
MG/L
117
1366
1459
1332
1832
1763
1718
1677
2004
1900
1507
1473
1726
1547
1558
1482
1509
1728
1756
1936
1834
1922
1626
1753
1674
1680
1732
1574
1494
1681
SVI
ML/G
118
179
151
123
123
130
128
119
95
111
133
136
110
129
128
135
156
139
137
129
136
151
185
196
209
208
219
270
261
155
VOLAT.
SOLIDS
£
119
79
78
79
79
77
77
77
79
81
78
76
79
76
77
76
77
78
77
78
79
79
78
82
79
78
78
77
77
78
N02
LOW
FLOW
GRAB
SAMPLE
MG/L
120
.030
.040
,010
.010
.080
.100
.060
.090
.120
.120
E
.100
.110
.120
.110
£
.110
.060
,050
.010
.020
.130
.090
.070
.140
.040
.120
.078
HIGH
FLOW
GRAB
SAMPLE
MG/L
121
.300
.320
< .010
.010
.770
.090
.070
.040
.090
.100
E
.080
.070
.120
.150
E
.090
,050
.050
.050
.060
.035
.090
.110
.100
.080
.100
< .121
N03
LOW
FLOW
GRAB
SAMPLE
MG/L
122
20.0
23.0
17.0
17.0
15.0
10.0
£
9.5
11.0
17.3
3.7
4.0
3.3
7.0
17.8
5.0
1.1
.2
Q
1.5
2.5
6.4
2.9
2.6
8.0
HIGH
FLOW
GRAB
SAMPLE
MG/L
123
30.0
29.3
19.3
20.0
11.0
15.9
13.3
24.9
19.0
9.0
E
9.6
3.5
14.5
24.2
E
8.0
1.4
1.0
1.1
3.1
15.0
7.1
6.4
9.7
7.4
8.3
12.5
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFFIC1ENT SAMPLE VOLUME, D-HOLIOAY NO ANALYSIS, E-INSUFUCIENT MANPOWER
F-ON-LINE INSTRUMf'T OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
(Jl
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN 0. PARKHURST - CHIEF ENGINEER £. GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
AERATION SYSTEM NO. 2
' SUSPENDED SOLIDS
24-HOUR COMPOSITES
P A C C
r tt J o
1
MG/L
124
2890
3043
3204
2942
2795
3005
3180
2895
3181
2915
3013
3088
3257
3015
306B
2926
2916
3182
3370
3181
3139
2966
3105
3123
3296
3149
3298
2658
3064
pACC • n A C C
" Ao j
2
MG/L
125
1735
1794
2010
2129
2084
1705
2100
1838
1970
1704
2071
1873
1827
2098
2073
1851
1783
2092
2092
2042
2110
1305
1772
1938
2012
1916
2023
1725
1935
r M o j
MG/L
126
1347
1417
1486
1510
1481
1561
1681
1697
1690
1613
1564
1340
1691
1588
1503
1614
1291
1531
1593
1421
1675
1494
1491
1611
1706
1687
1691
1334
1547
n A c c
r A J> o
4
MG/L
127
1306
1397
1539
1489
1434
1580
1644
1614
1639
1392
1563
1544
1705
1884
1674
1576
1447
1697
1575
1685
1655
1564
1408
1529
1612
1647
1638
1504
1569
RETURN
ACTIVATED
SLUDGE
c i rii/j
r L UH
RATE
MGD
128
2.35
2.38
2.28
2.09
2.57
2.09
2.03
2.15
2.28
2.24
2.07
2.20
2.09
2.03
2.19
2.14
2.16
2.22
2.15
2.08
2. 11
1.89
2.12
2.03
2.25
2.31
2.25
2.13
2. 17
A C. D A f
A c H A 1 .
VOLUME
KG
129
1.093
1.093
1,093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1 .093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
MIXED
LIQUOR
DISSOLVED
n if vr P M
U A T LJ C IN
MAX.
MG/L
130
MIN.
MG/L
131
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-1NSUFF1C IENT SAMPLE VULUMfc, D-HOLIDAY NO ANALYSIS, E-1NSUFF1C IENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER £ GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
VD
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
AERATION SYSTEM NO. 2
LOADING PATTERN
PASS
1
%
132
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
PASS
2
*
133
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
PASS
3
Z
134
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
PASS
4
%
135
.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
SVI GRAB SAMPLE
SETTL.
SOLIDS
ML/L
136
250
230
245
245
210
215
200
200
215
210
200
200
220
230
220
240
250
240
260
270
290
320
335
360
350
425
460
430
269
SUSP.
SOLIDS
MG/L
137
1343
1445
1532
1870
1852
1709
1728
1928
1904
1642
1817
1815
1675
1666
1607
1548
1769
1768
2122
1920
1922
1762
1720
1642
1810
1835
1674
1570
1736
SVI
ML/G
138
186
159
131
131
113
126
116
104
113
128
110
110
131
138
137
155
141
136
123
141
42
181
194
219
193
232
275
274
151
VOLAT.
SOLIDS
%
139
79
78
78
79
79
79
1
79
81
79
80
79
76
78
76
77
78
78
79
80
80
79
82
79
79
79
78
77
76
N02
LOW
FLOW
GRAB
SAMPLE
MG/L
140
.060
.050
.040
.020
.050
.100
E
.060
.070
.120
.100
.110
.120
.110
.020
£
.120
.060
.090
.080
.110
.130
.090
.170
.150
.070
.080
.087
HIGH
FLOW
GRAB
SAMPLE
HG/L
141
.350
.370
< .010
.090
.010
.730
.080
.090
.070
.110
.080
p
.060
.060
.220
.130
E
.090
.060
.060
.060
.090
.080
.090
. 100
.120
.060
.080
< .129
N03
LOW
FLOW
GRAB
SAMPLE
MG/L
142
20.0
20.7
22.8
13.9
17.0
8.0
E
8.5
16.0
19.2
3.7
E
3.3
4.0
6.5
20.8
E
7.0
2 5
2.2
L.8
2.4
4.0
7.1
7.6
3.0
1.9
9.0
HIGH
FLOW
GRAB
SAMPLE
MG/L
143
25.0
28.7
17.9
15.9
20.1
10. 0
19.3
15.9
20.0
19.0
7.5
E
6.6
3.0
16.0
31.3
E
10.0
2.4
2.6
2.6
4.8
12.0
7.4
4.1
7.6
4.1
4.1
12.2
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFFICIENT SAMPLE VOLUME, 0-HOLIDAY NO ANALYSIS, E-INSUFFICIF.NT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK dATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER £ GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
I
2
3
^
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
AERATION SYSTEM NO. 3
SUSPENDED SOLIDS
24-HOUR COMPOSITES
PASS
I
MG/L
144
2899
2935
3216
3282
2986
3215
3235
3020
2882
2860
2803
3098
3023
2905
2888
2735
2370
2721
3090
2988
3055
2762
2959
3063
3183
2984
3063
2606
2958
PASS
2
MG/L
145
1797
1901
2128
2251
2031
2251
2166
1988
1896
1845
1960
2018
1859
1953
2007
1896
1686
1791
2042
2042
2190
1960
1926
1866
2069
1949
1999
1787
1973
PASS
3
HG/L
146
1632
1544
1708
1663
1712
1700
1899
1652
1528
1650
1643
1723
1555
1498
1612
1576
1348
1466
1704
1601
1646
1490
1364
1566
1537
1577
1500
1419
1590
PASS
4
MG/L
147
1469
1446
1871
1848
1553
1745
1724
1665
1433
1443
1530
1601
1667
1492
1554
1439
1200
1683
1623
1535
1651
1492
1457
1604
1548
1525
1629
1518
1569
RETURN
ACTIVATED
SLUDGE
FLOW
RATE
MGD
148
2.51
2.54
2.59
2.31
2.57
2.47
2.22
2.21
2.30
2.29
1.98
2.13
1.93
1.92
2.05
2.11
2.02
2.04
1.98
2.02
2.05
1.76
2. 13
2.05
2.10
2.10
2.12
2.01
2.16
AERAT.
VOLUME
MG
149
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
1.093
MIXED
LIQUOR
DISSOLVED
OXYGEN
MAX.
MG/L
150
MIN,
MG/L
151
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFF1C IENT SAMPLE VOLUME, D-HOL1DAY NO ANALYSIS, E-I NSUFF 1C IENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CREEK WATER RtNOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN 0. PARKHURST - CHIEF ENGINEER & GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
AERATION SYSTEM NO. 3
LOADING PATTERN
PASS
•?
152
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
30.0
PASS
z
153
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
45.0
PASS
3
o>
*>
154
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
30.0
25.0
25.0
25.0
25.2
PASS
4
%
155
.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
SVI GRAB SAMPLE
SETTL.
SOLIDS
ML/L
156
270
230
210
270
250
245
220
200
210
200
200
180
215
200
210
230
240
200
235
250
270
310
290
330
320
360
380
395
254
SUSP.
SOLIDS
MG/L
157
1533
1436
1532
1990
1816
1704
1896
1993
1858
1544
1655
1651
1612
1480
1467
1435
1636
1421
1824
1877
1993
1742
1540
1583
1520
1760
1505
1445
1659
SVI
ML/G
158
176
160
135
136
138
144
116
100
113
129
120
109
133
135
143
160
147
141
129
133
135
178
188
208
211
205
252
273
155
VOLAT.
SOLIDS
*
159
80
78
78
79
77
77
78
79
81
78
79
79
77
78
75
76
77
78
79
80
80
79
81
79
78
79
77
76
78
N02
LOW
FLOW
GRAB
SAMPLE
MG/L
160
.050
.060
.050
.030
.040
.090
E
.060
.100
.130
.120
.120
.120
.110
.010
£
.120
.060
.090
.080
.070
.150
.100
.180
.150
.150
.090
.093
HIGH
FLOW
GRAB
SAMPLE
MG/L
161
.290
.360
< .010
.040
.010
.730
.090
.070
.020
.100
.090
E
.090
.070
.240
.050
e
.110
.070
.050
.060
.050
.100
.080
.090
.120
.110
.110
< .123
N03
LOW
FLOW
GRAB
SAMPLE
MG/L
162
16.0
21.1
21.2
13.5
15.0
7.5
10.5
15.0
17.0
3.7
c
2.0
5.0
6.5
21.2
p
7.5
3.0
2.3
2.0
1.8
4.6
5.6
7.8
2.5
1.5
4.6
8.7
HIGH
FLOW
GRAB
SAMPLE
MG/L
163
24.6
29.1
23.5
18.3
20.5
10.5
15.0
14.1
23.5
17.5
8.0
E
8.5
3.5
17.0
25.5
E
12.5
3.0
3.2
3.0
4.3
12.5
7.3
3.6
6.2
7.3
8.2
12.7
l-D
00
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFFICIENT SAMPLE VOLUME, D-HOLIDAY NO ANALYSIS, E-INSUFFICIENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
i-D
SAN JOSE CREEK WATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN 0. PARKHURST - CHIEF ENGINEER £ GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
1
2
3
4
5
6
7
3
9
10
11
I?
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
KINETIC PARAMETERS
AIR RATES
FEET/
GALLON
EFFLUENT
164
2.02
1.90
1 .95
1.96
2.08
2.02
1.85
1.98
1.99
1.92
1.92
1.94
1.96
1.95
2.10
1.98
2.03
2.02
2.02
2.00
1.91
1.93
1.92
2.06
2.02
2.06
2.01
1.9fl
1.98
FEET/
POUND
COD
165
948
1,042
933
806
762
1,031
650
996
1, 193
860
723
906
826
813
1,054
1,187
1,043
808
748
755
762
870
951
762
779
852
8t>6
827
884
COD
REMOVAL
%
166
88.3
85.9
93.3
93.6
91.9
86.1
90.9
89.2
87.0
91.8
93.0
92.1
91.1
90.3
91.6
90.1
91.4
90.6
92.3
91.6
91.7
91.7
91.7
94.2
92.0
94.2
92.7
92.3
91.2
AERATION
SYSTEM
LOAD
LBS.
167
66,000
60,600
48,600
56,200
65,600
51, 100
76,200
47,300
42,000
55,300
64,900
51,900
56,300
57,900
47,600
39, 100
45,900
58,900
61,300
60,500
57,900
48,300
45,800
59,400
61 ,300
56,400
55,100
56,600
55,500
TOTAL AERATION
AERATION
SYSTEM
i
LBS.
168
61 ,800
67,900
70,400
70,400
66,500
69,900
71,300
67,600
65,500
61 ,700
68,100
59,600
66,800
59,600
61 ,000
61,600
65,400
70,600
71,300
72,200
69, 100
65,400
65,600
67,700
68,300
66,700
65,500
58,300
66,296
AERATION
SYSTEM
2
LBS.
169
61.400
67,500
68,000
67,700
64,300
66,200
69,400
65,200
66,600
60,900
67,400
63,300
66,000
63,200
63,600
62,500
63, 100
71,200
73,500
71 , 100
69,600
65,100
63,200
67, 100
69,300
67,700
68,000
58,500
66,093
AERATION
SYSTEM
3
LBS.
170
64,200
68,400
71,300
72,700
67,000
72,300
71,800
66,800
62,600
61,800
65,800
66,900
63, 700
59,700
62,300
61,000
58,700
65,900
72,300
70,600
69,300
64,500
62 ,600
66,200
67, 700
65,800
65,200
59,200
65,939
MIXED LIQUOR
AERATION
SYSTEM
1
LBS.
171
26,300
28,000
31,500
31,900
30,300
30,900
33,000
31 ,000
30,500
28,600
31,100
28,800
31, 100
28,700
28,600
28,500
29,100
30,800
30,500
31,100
31,100
28,200
29,700
29,800
30,700
29,700
29,600
26,300
29,836
AERATION
SYSTEM
2
LBS.
172
26,200
27, 500
29, 700
29,900
29,000
28,500
31,700
29,900
31,100
28, 100
30,300
28.000
30,800
31,600
30,400
29,400
26,600
30,900
31,200
29,900
31,700
28,500
28,000
30,000
31,500
30,800
31,600
26,300
29,611
AERATION
SYSTEM
3
LBS.
173
28,900
28,800
32,800
33,200
30,900
33,000
33,800
30,800
28,600
29, 100
29,800
31,300
29, 500
28,900
30,000
28,600
24,700
28,200
31,300
30,200
31,700
28,600
27,900
29,500
30,400
29,600
29,800
27,100
29,893
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFFICIENT SAMPLE VOLUME, D-HOLIDAY NO ANALYSIS, E-INSUFF1CIENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
SAN JOSE CRFEK WATtR RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY, CALIF.
JOHN 0. PARKHURST - CHIEF ENGINEER £ GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
I
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MEAN
KINETIC PARAMETERS
CENTROI DAL
RETURN SLUDGE
AERATION TIMES
AERATION
SYSTEM
1
MRS.
174
1 1.46
11.26
12.61
11.98
10.21
11.51
12.03
12.26
12.61
13.05
13.25
13.52
14.26
15.71
13.88
14.18
13.32
13.05
13.66
14.18
14.03
15.08
13.73
12.92
13.66
12.92
13.52
13.88
13. 13
AERATION
SYSTEM
2
MRS.
175
11. 16
11.02
11.51
12.55
10.21
12.55
12.92
12.20
11.51
11.71
12.67
11.92
12.55
12.92
11.98
12.26
12. 14
11.82
12.20
12.61
12.43
13.88
12.37
12.92
11.66
11.36
11.66
12.32
12. 11
AERATION
SYSTEM
3
HRS.
176
10.45
10.33
10. 13
11.36
10.21
10.62
11.82
11.87
11.41
11.46
13.25
12.32
13.59
13.66
12.80
12.43
12.99
12.86
13.25
12.99
12.80
14.90
12.32
12.80
12.49
12.49
12.37
13.05
12.25
MIXED LIQUOR
AERATION TIMES
AERATION
SYSTEM
1
HRS.
177
4.08
3.93
4.99
4,95
4.68
4.76
4.51
5.06
4.96
4.85
4.87
4.94
5.15
5.20
5.06
5.23
5.07
5.09
5.21
5.27
5.19
5.53
5.25
5.21
5.07
4.97
5.01
5.07
4.97
AERATION
SYSTEM
p
HRS.
178
4.06
3.91
4.88
5.00
4.68
4.85
4.58
5.05
4.85
4.74
4.82
4.81
5.01
5.00
4.90
5.06
4.97
4.98
5.08
5.13
5.06
5.43
5.13
5.21
4.89
4.82
4.84
4.94
4.88
AERATION
SYSTEM
3
HRS.
179
4.00
3.86
4.73
4.88
4.68
4.67
4.49
5.02
4.84
4.71
4.87
4.84
5.10
5.06
4.97
5.08
5.04
5.08
5.17
5.17
5.09
5.52
5.12
5.20
4.97
4.93
4.91
5.00
4.89
HYDRAUL 1C
RETURN SLUDGE
AERATION TIMES
AERAT ION
SYSTEM
1
HRS.
180
AERATION
SYSTEM
2
HRS.
181
AERATION
SYSTEM
3
HRS.
182
MIXED LIQUOR
AERATION TIMES
AERATION
SYSTEM
1
HRS.
183
6.38
6. 14
7.81
7.74
7.32
7.45
7.06
7.91
7.76
7.59
7.61
7,73
8.05
8. 14
7.91
8. 13
7,93
7.97
8.15
8.24
8.13
8.65
8,22
8. 16
7.93
7.7tt
7.83
7.93
7.78
AERATION
SYSTEM
2
HRS.
184
6.35
6.12
7.64
7.83
7.32
7,60
7.16
7.90
7.59
7.41
7.54
7.52
7.84
7.83
7.66
7.92
7.77
7.79
7.95
8.03
7,91
8.50
8.03
8.16
7.65
7.55
7.58
7.73
7.64
AERATION
SYSTEM
3
HRS.
185
6.26
6.04
7.40
7.64
7.32
7.31
7.03
7.85
7.58
7.37
7.61
7.58
7.97
7.92
7.78
7.95
7.89
7.94
8, 10
8.09
7.97
8.63
8.02
8.14
7.78
7.72
7.68
7.83
7.66
O
O
A-SAMPLER MALFUNCTION. B-ANALYTICAL ERROR, C-INSUFFJCIENT SAMPLE VOLUME, D-HOLIDAY NO ANALYSIS, E-INSUFFICIENT MANPOWER
F-ON-L1NE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
-------
NJ
O
SAN JOSE CREEK HATER RENOVATION PLANT
COUNTY SANITATION DISTRICTS OF LOS ANGELbS COUNTY, CALIF.
JOHN D. PARKHURST - CHIEF ENGINEER £ GENERAL MANAGER
*** SUMMARY OF OPERATIONS ***
FEBRUARY 1975
DATE
i
2
3
4
5
6
7
8
g
10
11
12
13
14
15
16
17
18
19
20
21
22
23
2*
25
26
27
28
MEAN
KINETIC PARAMETERS
COO LOADING
LBS. COD/
TPVSS/
DAY
186
.36
.31
.24
.27
.34
.25
.55
.24
.21
.31
.33
.27
.30
.33
.26
.22
.26
.29
.29
.29
.28
.25
.24
.30
.31
.29
.29
.33
.29
LBS. COD/
MLVSS/
DAY
187
1.02
.92
.66
.75
.94
.71
1.46
.65
.57
.82
.90
.75
.81
.84
.71
.59
.73
.84
.84
.83
.77
.72
.66
.84
.85
.80
.78
.93
.81
DAILY
RES.
DAYS
188
17.9
15.6
42.7
17.3
13.6
13.7
15.1
13.7
13.0
13.4
14.5
17.0
14.8
14.6
22.8
40.2
30.2
39.3
16.1
9.6
9.8
12.3
14.3
15.8
15.5
11.3
10.8
7.1
17.6
SOLIDS BALANCE
TOTAL
SUSPEND.
SOLIDS
LBS.
189
229,800
248,300
262,200
265,100
247,200
260,100
267,400
252,000
244,600
229,100
249,200
240,000
247,800
227,500
238, 100
232.500
230,800
260,000
268,700
265,000
261,100
243,200
238,200
249,600
255,800
250,000
249,300
222,000
247,671
WASTED
LBS.
190
569
498
3,964
14,042
16,341
17,451
15,868
17,019
17, 318
15, 160
15,271
12,650
15,345
14,459
9, 184
4,550
6, 195
5,912
15,107
26,289
25,122
18,408
15,932
14,426
15,460
20,823
22,003
30,608
14,499
SEC.
SUSPEND.
SOLIDS
LBS.
191
12,286
15,444
2,170
1,260
1,841
1,497
1,828
1,410
1,459
1,893
1,892
1,494
1,438
1,089
1,278
1,232
1,440
712
1,576
1,394
1,416
1,332
694
1,376
1,088
1,281
1,101
728
2,273
DAILY
GROWTH
LBS.
192
18255
34442
20034
18202
282
31848
24996
3029
11377
1553
37263
4944
24583
-4751
21062
182
5935
35824
25383
23983
22638
1840
11626
27402
22548
16304
22404
4035
16686
AVERAGE
GROWTH
IKGROWTH/
fSYSTEH
DAY
193
.068
.069
.064
.062
.062
.061
.062
.066
.069
.071
.072
.073
.077
.054
.053
.052
.050
.051
.051
.052
.051
.051
.053
.05*
.053
.054
.055
.069
.060
AVERAGE
RES.
DAYS
194
14.6
14.5
15.6
16.0
16.2
16.3
16.0
15.2
14.5
14.1
13.9
13.6
13.0
18.6
13.8
19.3
19.9
19.8
19.7
19.1
19.8
19.8
19.0
18.9
18.9
18.5
18.1
14.5
17.0
A-SAMPLER MALFUNCTION, B-ANALYTICAL ERROR, C-INSUFF1CIENT SAMPLE VOLUME, D-HOLIOAY NO ANALYSIS, E-INSUFF1CIENT MANPOWER
F-ON-LINE INSTRUMENT OUT OF SERVICE
EXAMPLE OF MONTHLY REPORT
SUMMARIZING ALL DATA AND CALCULATIONS
APPENDIX (CONTINUED)
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 . REPORT NO.
EPA-600/2-75-058
3. RECIPIENT'S ACCESSI ON-NO.
4. TITLE AND SUBTITLE
State of the Technology
SEMI-AUTOMATIC CONTROL OF ACTIVATED SLUDGE
TREATMENT PLANTS
5. REPORT DATE
December 1975 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Carl A. Nagel
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
County Sanitation Districts of Los Angeles County
1955 Workman Mill Road
Whittier, California 90607
10. PROGRAM ELEMENT NO.
1BB043; ROAP 21-ASC; Task 31
11. CONTRACT/GRANT NO.
R803 055-01-0
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report documents the theory, design and operation of continuous on-line
instrumentation currently in use by the County Sanitation Districts of Los Angeles
County California and further describes computer applications which provide daily
operational calculations.
Instrumentation sections include Water Level Control of Influent Pumping, Density
Control of Primary Sludge Pumping, and Process Air, Return Sludge and Waste Sludge
Control in Activated Sludge Plants. Theory, design, operation and maintenance
characteristics, maintenance requirements, and results are presented for each system
A computer application system is described which provides daily operational para-
meters to the operators and prepares monthly summary of operations reports. A
review of other computer applications and a subroutine to compare effluent charac-
teristics with discharge limits is included.
This report was submitted in fulfillment of Contract Number R 803 055-01-0, by the
County Sanitation Districts of Los Angeles County, under the sponsorship of the
Environmental Protection Agency. Work was completed as of March 1975.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Automatic control
Automatic control equipment
Data processing
Data storage
Data retrieval
Waste treatment
Waste water
Influent pumping control
Sludge pumping control
Process air control
Waste activated sludge
control
13B
13. DISTRIBUTION STATEMEN1
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)'
UNCLASSIFIED
21. NO. OF PAGES
212
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
202
*USGPO: 1976-657-695/5356 Region 5-1
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