B»A 910/946-146
Agwey
Region 10
1200 Sixth AVOTIM
i WA 98101
Idaho
Oregon
Washington
October 1988
Upgraded Diagnostic
Operational Modeling
Programs for Municipal
Wastewater Treatment
Plants and Troubleshooting
Program for Activated
Sludge - IBM Version
User's Manual
IBM Version
-------
DIAGNOSTIC OPERATIONAL
MODELING PROGRAMS
FOR
MUNICIPAL WASTEWATER
TREATMENT PLANTS
USER'S MANUAL
IBM VERSION
-------
DISCLAIMER
This publication was prepared with the support of
a. grant from the U.S. Environmental Protection Agency's
Municipal Operations Branch. The statements, conclusions
and/or recommendations contained herein are those of the
authors and do not necessarily reflect the views of the
U.S. Government, the U.S. Environmental Protection Agency,
or Linn Benton Community College, nor does mention of
trade names or commercial products constitute endorsement
of recommendation for use.
-------
FOREWORD
The Diagnostic Operational Programs were first released in 1982.
Since that time the programs have been used extensively by professionals
throughout the wastevater treatment field to evaluate treatment plant
design limitations and operational deficiencies. Comments and suggestions
from program users have been actively solicited since 1982 to serve as a
basis for further improvements to the original programs. Where possible,
the programs have been updated and improved using information obtained
from end users of the programs. In addition, further modifications have
been made which increase the flexibility of the programs thereby simpli-
,fying program use. This User's Manual describes the operation and use of
the newly released, updated diagnostic programs. It is important' to read
the Tff*"!?1 through its entirety since many significant changes have been
made to the original programs.
-------
TABLE OF CONTENTS
CHAPTER 1 INTRODUCTION 1-1
1.1 Limitations 1-4
CHAPTER 2 USING THE COMPUTER 2-1
2.1 Computer System Components 2-1
2.2 Computer 2-2
2.3 Floppy Disk Drives 2-3
2.4 CRT 2-4
2.5 Printer 2-5
2.6 Diskettes 2-5
2.7 Quad or High Density Disk Drives 2-7
2.8 Computer Compatibility 2-7
CHAPTER 3 RUNNING THE PROGRAMS 3-1
3.1 Beginning the Run 3-2
3.2 Selecting the Desired Treatment Plant Type 3-2
3.3 Using the Function Menu • 3-2'
OPTION NO. 1: INPUT A NEW PLANT 3-3
General Questions 3-3
Treatment Plant Configuration 3-4
CLARIFIER QUESTIONS 3-5
REACTOR QUESTIONS 3-5
REAERATION TANKS 3-5
CONTACT TANKS 3-5
TRICKLING FILTERS 3-6
ABF TOWERS ONLY 3-6
SLUDGE DIGESTION QUESTIONS 3-6
AEROBIC QUESTIONS 3-7
ANAEROBIC QUESTIONS 3-7
OPTION NO. 2: RECALL/EDIT A NEW PLANT 3-7
THE EDIT MENU 3-8
OPTION NO. 3: RUN MATHEMATICAL MODEL 3-8
OPTION NO. 4: RETURN TO MAIN MENU 3-9
-------
CHAPTER 4 APPLICATION AND THEORY 4-1
INTRODUCTION 4-1
INPUTTING WASTEWATER CHARACTERIZATION DATA 4-1
AVERAGE DRY WEATHER FLOW, MGD 4-2
PEAK DAILY DRY WEATHER FLOW, MGD 4-2
DESIGN FLOW MGD 4-2
INFLUENT BOD, MG/1 4-2
INFLUENT TSS, MG/1 4-3
INFLUENT VSS, % 4-3
TEMPERATURE °C 4-3
TKN, MG/1 4-3
ALKALINITY, MG/1 4-4
pH, UNITS 4-4
P04-P, MG/1 4-4
PLANT CONFIGURATION AND DIMENSIONS 4-4
COMPUTER PRINTOUT FORMATS, GENERAL 4-5
PRIMARY SYSTEM PERFORMANCE AND LOADINGS 4-5
CLARIFIER SURFACE, GROUP 4-5
WEIR LOADING, GPD/FT 4-5
DETENTION TIKE, HRS 4-6
PERCENT REMOVAL BOD, PERCENT REMOVAL TSS 4-6
PRIMARY CLARIFIER EFFLUENT BOD AND TSS, MG/1 4-7
PRIMARY SLUDGE PRODUCTION, LBS. TSS 4-8
PRIMARY SLUDGE PRODUCTION, LBS. VSS 4-8
PRIMARY SLUDGE PRODUCTION, Z SOLIDS 4-8
PRIMARY SLUDGE PRODUCTION, GPD 4-9
MASS BALANCE 4-10
ACTIVATED SLUDGE SYSTEMS MODEL AND LOADINGS 4-11
ADDITIONAL INPUT VALUES 4-11
REACTOR DIMENSIONS 4-11
CLARIFIER DIMENSIONS 4-11
MAXIMIZING THE REACTORS AND CLARIFIERS 4-11
ADDITIONAL INPUT PARAMETERS 4-15
BIOLOGICAL PERFORMANCE SHEETS 4-16
MAXIMUM MLSS 4-16
MLVSS 4-16
F/M 4-16
MCRT DAYS 4-16
RAS MG/L 4-18
WAS, LBS/DAY 4-19
DETENTION TIME, HOURS OR DAYS 4-19
LOAD, LB BOD/1000 FT3 4-19
OUR, MG/L/HOUR 4-19
0, RQD, LBS/DAY 4-20
FINAL CLARIFIER PERFORMANCE AND
EFFLUENT CHARACTERISTICS 4-20
DETENTION, TIME, HOURS 4-20
DOB, FT 4-21
EFF, BOD, MG/L and EFF, TSS, MG/L 4-21
EFF, NH3, MG/L and EFF, NO-, PO,, MG/L 4-21
SECONDARY SYSTEM PERFORMANCE 4-22
CLARIFIER LOAD, SFC, GPSFD 4-22
CLARIFIER LOAD, WEIR GPLFD 4-22
11
-------
Sludge Production 4-23
Percent Solids 4-23
GPD - Gallons 4-23
VARIATIONS IN ACTIVATED SLUDGE PROGRAMS 4-23
Activated Biofliter Systems 4-23
Contact Stabilization 4-23
FIXED FILM SYSTEMS MODEL AND LOADINGS 4-24
ADDITIONAL INPUT VALUES 4-24
PROCESS ALGORITHMS 4-25
SECONDARY SYSTEM LOADING AND PERFORMANCE SHEETS 4-23
Filter, Surface Loading , 4-28
Filter Loading, Pounds of BOD, 1000 Ft 4-28
Filter Loading for Two Stage Filters 4-28
Clarifier Loadings, Surface GPDSF, Weir, GPD/FT 4-28
Clarifier Detention Time, Hours 4-28
Effluent BOD and TSS Concentration 4-28
Secondary Sludge Production 4-29
Total Sludge Production 4-29
ROTATING BIOLOGICAL CONTACTORS (RBC) 4-29
DIGESTER PERFORMANCE SHEETS 4-30
Total Sludge Flow, Gallons Per Day 4-30
Volatile Solids Loading in Lbs/FtVDay 4-30
Mean Cell Residence Time, Days 4-30
Percent Reduction of Volatile Solids 4-31
Alkalinity, mg/1 4-31
Gas Production, Ft^ Per Day 4-31
Percent Solids of Digested Sludge 4-31
CHAPTER 5 DIGESTER AND ACTIVATED SLUDGE ANALYTICAL
AND TROUBLESHOOTING PROGRAMS 5-1
INTRODUCTION 5-1
RUNNING THE DIGESTER PROGRAM 5-1
CALCULATED VALUES 5-3
Detention Tine, Days 5-3
Organic Loading, Pounds of Volatile Solids
Per Cubic Foot Per Day 5-4
Reduction of Volatile Solids in Percent 5-4
Reduction of Volatile Solids in Pounds
Per Day 5-4
Gas Yield in Cubic Feet of Gas Produced
per Pound of Volatile Matter Destroyed 5-5
Alkalinity/Volatile Acid Ratio 5-5
PREDICTED VALUES 5-8
iii
-------
Reduction of Volatile Solids,
Founds per Day
Digester Liquor Solids, Percent
Digester Volatile Solids in Percent
Gas Production in Cubic Feet x 1,000
Alkalinity as CaC03 in mg/1
Comparison of Theoretical Data with
Calculated Data
Design Parameters
Operating and Analytical Data
Check Digester Loading
Check Digester Detention Time
Check Materials Balance
ACTIVATED SLUDGE ANALYSIS
Inputting Data
PROGRAM THEORY
RUNNING THE EXAMPLE PROGRAM
5-9
5-9
5-9
5-10
5-10
5-10
5-11
5-11
5-11
5-12
5-12
5-16
5-16
5-21
5-23
APPENDIX A
APPENDIX B
APPENDIX C
APPENDIX D
APPENDIX E
APPENDIX F
APPENDIX G
APPENDIX H
ALGORITHM SOURCES
INFLUENT AND EFFLUENT WASTEUATER DATA SHEETS
TREATMENT PLANT CONFIGURATION DATA SHEETS
DEFINITION OF OUTPUT PARAMETERS
REPRESENTATIVE VALUES FOR OUTPUT PARAMETERS
DO'S AND DON'TS OF COMPUTER OPERATION
IDEALIZED MATHEMATICAL MODEL OF EL CENTRO,
CALIFORNIA PRIMARY WASTEWATER TREATMENT SYSTEM
ZONE SETTLING VELOCITY TEST
iv
-------
CHAPTER 1
INTRODUCTION
In general, undesirable effluent quality from municipal wastewater
treatment plants results from one of two general causes. The first is
that treatment plants become overloaded or do not have adequate capacity
in one or more unit processes to produce effluent of a desired quality.
The second is that plants are not being operated properly. In this manual,
the former "111 be referred to as a "process limitation" and the latter
will be referred to as an "operational deficiency." Distinguishing be-
tween the two is not always easy. The Diagnostic Operational Modeling
Programs are intended to provide a reliable and rapid means of identify-
ing process limitations and operational deficiencies. Programs for the
following eleven types of municipal wastewater treatment plants are
available:
1. Primary treatment
2. Conventional activated sludge, with or without primary
sedimentation
3. Single stage activated sludge for nitrification, with
or without primary sedimentation
4. Extended aeration activated sludge with or without
primary sedimentation
5. Extended aeration oxidation ditch with or without primary
sed Imentat ion
6. Contact stabilization, with or without primary sedimentation
7. Single stage trickling filter with primary sedimentation
8. Two stage trickling filter with primary sedimentation
9. Activated Bio-Filter, with or without primary sedimentation
10. Rotating biological contactors with primary sedimentation
11. Roughing filter followed by activated sludge
1-1
-------
Each program allows for the option of selecting either anaerobic
or aerobic sludge digestion analysis.
These programs have been prepared for use with the IBM PC/XT Compaq,
AT&T or IBM compatible PC microcomputers. The eleven diagnostic programs
have been prepared on a set of seven diskettes. Some of the diskettes are
used for modeling only one type of wastewater treatment plant while others
are used to perform diagnostic runs on various types of wastewater treat-
ment plants. The specific wastewater treatment plant configurations
available on each of the program diskettes are listed as follows:
DISKETTE NAME
1. Roughing Filter
2. Activated Sludge without
Primary Clarifiers
3. Contact Stabilization
4. Trickling Filter
BBC and Separate Primary
Treatment
Activated Sludge with
Primary Clarifiers
7- Activated Biological
Filter CABF)
TREATMENT PLANT TYPE
A. Activated Sludge with Roughing
Filter
A. Conventional Activated Sludge
B. Single-Stage with Nitrification
C. Extended Aeration
D. Oxidation Ditch
A. Contact Stabilization with
Primary Clarifiers
B. Contact Stabilization without
Primary Clarifiers
A. Single-Stage Trickling Filter
B. Two-Stage Trickling Filter
A. Rotating Biological Contactor
B. Primary Treatment Only
A. Conventional Activated Sludge
B. Single-Stage with Nitrification
C. Extended Aeration
D. Oxidation Ditch
A. ABF with Primary Clarifiers
B. ABF without Primary Clarifiers
1-2
-------
The subsequent three chapters of this manual describe how to use the
Diagnostic Operational Modeling Programs. Chapter 5 discusses two new
programs to analyze activated sludge systems and digestion systems using
actual plant data. They are intended to augment the above diagnostic
models by providing additional information to troubleshoot problems in
the field.
Chapter 2 describes the physical set-up of the computer system and
presents several important "do's and don'ts" intended to prevent the
user from damaging the computer or the diskettes.
Chapter 3 contains a step-by-step description of how to run the
programs and obtain numerical output. This chapter also contains several
important recommendations and warnings about storing and using the disk-
ettes.
Chapter 4 presents guidelines for interpreting the program output
and a discussion of the limits of accuracy of the programs as well as
theory and equations pertaining to algorithm derivation and interpretation.
Before using the Diagnostic Operation Modeling programs for the
first time, it is recommended that the user read through the first three
chapters of this manual, as well as appendices which are referenced in
those chapters.
Note: Before using the PC computer for the first time, it
is strongly recommended that the user read the
users manuals for the computer, printer, disk drives,
and monitor provided by the manufacturers.
Taking the time to read these other manuals will greatly reduce the
chance of accidental damage or misuse of this equipment. It will also
save a great deal of time in the long run, and make using the computer
more enjoyable.
1-3
-------
1.1 Limitations
In general, a ma^™"" of ten individual treatment units per type
of unit process is allowed (.i.e., ten primary clarifiers, ten aeration
basins, ten RBC's per BBC train, etc.). If a plant has more than ten
of any type of treatment unit, the plant can still be accurately modeled
by using, for example, half the flow with half the actual number of
units. To do this, all the units would have to be of the same size and
configuration. If not, the user must exercise his own judgment in
deciding whether or not he can approximate the actual plant configuration
in some way which results in less than ten units for each unit process.
The programs may not produce accurate results for small plants
such as package plants, due to rounding of numbers by the computer.
If erroneous results occur then multiply the appropriate values by a
factor of ten. These values are: average flow, peak flow, primary
clarifier area, reactor volume, filter volume or RBC surface area and
final clarifier surface area, as appropriate. Do not increase the
clarifier depths or MLSS concentrations. If the plant being analyzed
is a package plant with non-conventional clarifiers with low surface
loadings (<250 gpdpsf) then the effluent BOD and TSS predictions may be
substantially lower than actual capability because the programs assume
conventional clarifiers at 502 plug flow.
1.2 Availability of Programs
Additional copies of the Users Manual and programs are available
from I.R.I.S. Also the programs are available on a 3% inch double
sided, quad density disk. For further information write to:
Instruction Resources Information Systems
Ohio State University
1200 Chambers Road
Columbus, Ohio 43212
Attn: Dr. Robert Howe
Telephone: C614) 422-6717
1-4
-------
CHAPTER 2
USING THE COMPUTER
This chapter presents a non-technical discussion of how to prepare
the IBM compatible computer for use with the Diagnostic Operational
Modeling Programs. It is based on the combined experience of the individ-
uals who developed the program formats specifically to be used on this
computer system, and is meant to be as simple and foolproof as possible.
We recommend that users follow the procedures in this chapter carefully
until they are thoroughly familiar with the programs, as well as the
capabilities and limitations of the computer itself, before attempting
to modify these procedures in any way. •
Note: This chapter is not a substitute for manufacturers'
manuals provided with the computer hardware. Those
manuals must be read carefully before following any
instructions in this manual.
2.1 Computer System Components
The program formats were developed using the following standard
components:
1. Computer — IBM compatible with a minimum 256K random
access memory (RAM)-
2. Disk Drives — One or two disk drives with a controller
card. Also a hard disk may be used.
3. CRT — Various manufacturers.
4. Dot Matrix Printer — Epson or compatible, using a
parallel or serial port.
5. Diskettes — 5% inch diameter, various manufacturers,
double side double density.
2-1
-------
The first step in running the programs is to set up the computer in
a suitable work area. A table or desk at least two feet wide and four
feet long will be required to hold the computer without crowding.
Additional work space, particularly an "L" shaped arrangement, is very
helpful. The computer, printer and CRT each require a 110 volt power
supply. Power cords should be kept out of the way to avoid accidental
unplugging of the equipment. Set the computer in the center of the work
space. The CSX can either be placed directly on top of the computer or
directly behind it, unless it is built into the computer.
After reading the manufacturers instructions carefully, plug the
printer and the CRT into the computer. Make sure that the main power
switches on the computer, printer and CRT are turned off, and then plug
these units into the power source.
Rote: Do not turn on the power to any of these units yet.
2.2 Computer
The computer is the heart of the system. The keyboard provides
the user with a means of entering data and commands for the computer to
act on. Commands given internally by the computer activate the printer
and disk drive(s) while the Diagnostic Operational Modeling Programs are
being run.
It is very important that the computer (and all other system com-
ponents) and the area around them be kept clean and dry. Use a dry or
lightly moistened dust cloth for cleaning. Avoid using too much water.
Do not use any cleaners whatsoever. Never put open beverage containers,
flower vases, etc., on the table where the computer is kept, or on over-
head shelves near the computer. Excessive moisture can severely damage
or destroy the computer.
Note: The computer, when in operation, will cause electrical
interference to some instruments and most radio and
television receivers.
2-2
-------
2.3 Ploppy Disk Drives
A nH^-hmim of one disk drive is needed to store and read the diag-
nostic programs and data. However, two double sided double density
disk drives are recommended due to the limited amount of storage space
available when only using a single disk drive. Drive A (.i.e., the
primary drive) is used to read in the Diagnostic Operational Modeling
Programs. This drive is also used to permanently store individual
treatment plant data files when only using one disk drive. If your
system has two drives, individual treatment plant data files can be
stored on Drive B. This will be discussed in more detail in Chapter 3.
When in use, each drive holds only one diskette. To insert a
diskette into the drive, first open the door on the front of the
drive. It will flip up or swivel and allow access to the horizontal
slot in the front of the drive. Diskettes are stored in protective
paper packets. Remove the diskette from the packet by holding it so
the label is on top and in the lower right corner as you look down at
it. Put your right thumb over the label, and gently remove the
diskette from the packet, and insert it into the drive without turning
it so that the label remains on top and in the lower right corner as
you look down at the drive. If you have vertically mounted disk drives,
then it may be necessary to rotate the disk counterclockwise to enable
them to fit properly. Close the drive door by pushing down on the
plastic flap or rotate until it flips back down.
Note: Never let anything touch the brown or grey
surface of the diskette. Handle the diskette
by the plastic cover only. Always keep
diskettes in the paper packet when they are
not in use.
2-3
-------
Note: Never turn the computer on unless there is a
diskette in appropriate Drive or unless you
have a hard disk. It is not necessary to
have one in a Drive.
To remove a diskette, simply open the drive door by pushing in
on the top of the flap or swiveling the lever. Carefully pull the
diskette out of the drive, and put it back in the paper packet.
Note: Always check the red "in use" light on the drive
before removing diskettes. Never remove a diskette
while the "In use" light is on. This can destroy the
information on the diskette.
Note: Don't leave diskettes in the drives overnight.
Note: The disk drives require cleaning periodically to
remove dirt and magnetic particles from the read/
write head. Cleaning kits with instructions are
available from most computer stores.
2.4 CRT
Hany CRT's are available from various manufacturers for use with
IBM compatible computers. They vary widely in detail and in orienta-
tion of controls, so the user should become familiar with the one
provided. Eyestrain is a common symptom of heavy computer use, so
take some time to place the CRT where it is easiest to look at for
long periods of time. Changing contrast and brightness settings may
be helpful if lighting conditions in the room change during the day.
Note: Hany users have found that looking at the CRT for
long periods of time under fluorescent lights gives
them headaches. This is caused by the screen and
lights flickering together very quickly. This
problem can be minimized by changing to incandescent
lighting or taking breaks at regular intervals.
2-4
-------
2.5 Printer
The users im»™»ai prepared by the manufacturer contains all the
Information needed to use an Epson (or compatible) dot matrix printer
properly. Therefore, normal operating instructions will not be repeated
in this T
One addition to the normal instructions which previous program
users have found handy is to place a standard office-type "in-out"
basket behind the printer to receive the output. Paper going into the
printer should run underneath the basket. When properly arranged, the
output will fold itself neatly in the top part of the basket and prevent
output from being fed back into the printer, which jams the machine.
This allows the user to devote attention to other matters while a run
is being printed.
2.6 Diskettes
Diskettes are very similar to cassette tapes, except in physical
ways. Therefore, you must use the same precautions to keep them from
being damaged. These include the following:
1. Never put a diskette in a hot area such as in the sunlight
area of a window or near an oven, heater, electrical panel
or lamp.
2. Keep the diskettes away from magnetic fields at all times.
This includes: motors, instruments, magnets ,. metal cab-
inets, electrical cords, etc.
3. Store the diskettes in a cool dry place. Moisture can
cause fatal damage to the surface area of the diskette.
Diskettes should be stored vertically in a closed
container. Special storage containers are available
from most computer stores.
Since the diskettes can be damaged very easily and since it is
nearly impossible to "repair" a damaged one, it is strongly recommended
that each user station keep two complete sets of diskettes. One set
2-5
-------
should be a working set available for day-to-day use. The second set
should be retained as a backup in case something happens to a working
diskette. If a working diskette becomes damaged or is lost, the backup
diskette should be used as the working diskette and another copy made
to become the new backup diskette. The diskettes can be copied by
using most any copy program including the disk copy program.
If you have a hard disk then you may desire to download (or copy)
the diskettes onto the hard disk. You must transfer each diskette into
its own subdirectory. Warning; The programs will not work properly
on a hard disk unless they are copied into separate subdirectories.
The procedure to download to the hard disk is:
1. Place one of the program disks in Drive A. Type in:
A: .
2. Type in: MKDIR . The is the name
of the subdirectory that the program will be transferred
to, e.g., MKDIR RBC, would be a proper way of doing this.
The MKDIR is the "make subdirectory" command. You must
use only letters and no more than eight for the name.
3. Type in: Copy *.* C: \ . Use the same
as Step 2.
4. Repeat steps 1 through 3 for each process you wish to
download. Remember to use different s each time.
5. When running, you will need to go into the subdirectory of
the process you wish to run. Type in: CD .
Use the proper subdirectory -
6. Follow the running instruction in Section 3.1, omitting
Step 4.
7. When you have finished you will want to return to the
main directory. Type in: CD\.
2-6
-------
2.7 Quad or High Density Disk Drives
When using an IBM AT compatible with high density drives you can
use the exact procedures as for the hard disk, when downloading the
programs. It is highly recommended that you download the programs.
In Step 3 specify the high density Drive A or B by replacing the C:
in the typed in line with A: or B:, whichever is proper. Be sure to
format the blank high density disk before downloading.
2.8 Computer Compatibility
The diagnostic programs have been tested on the following computers
for compatibility.
1. IBM PC
2. IBM XT
3. IBM AT (recommended to transfer to quad density disks)
4. AT&T
5. Panasonic Portable
6. HP Vectra
7. ITT
8. Toshiba Portable W Format)
2-7
-------
CHAPTER 3
RUNNING THE PROGRAMS
This chapter contains instructions on how to run the Diagnostic
Operational Modeling Programs. These programs are conversational in
nature, which means that the computer will ask the user a series of
questions before the computations start. The answers to these questions
will guide the computer in its work. The emphasis of this chapter is to
explain to the user how each of these questions affects the computations
so that users can obtain output best suited to their needs.
The question and answer format of each program is intended to be
easy to follow. The majority of the questions asked refer either to the
physical configuration of the plant to be modeled or to the wastewater
characteristics to be used in the run, and are self-explanatory. For
this reason, not all of the questions the user will need to answer are
specifically addressed in this manual. The user should understand that
incorrect answers will not hurt the programs in any way but will affect
the output.
Before proceeding, the user is advised to prepare data sheets with
the wastewater characteristics and plant configuration to be used in the
run. Forms which indicate the necessary information are contained in
Appendices B and C of this manual. In addition, the printer must be used
with the LPT1 output port.
As previously mentioned, the programs can be run from either a one or
two disk drive system; If you have only one drive, you will be limited
to the number of treatment plant files that you can store on the disk
unless a hard disk is used. If you have two drives, you will need a
formatted disk in drive two in order to save plant data files. To format
a data disk, see your disk operating system reference manual under the
3-1
-------
disk, see your disk operating system reference manual under the section
of formatting a disk. You can use as many of these "DRIVE B" disks as
you need, thus as they fill up, you can switch to another empty (for-
matted) disk to add more files.
3.1 Beginning the Bun
The last steps the user should perform before the first run are
the following:
1. Load paper into the printer. Advance the paper so that a
horizontal perforated line is about ^ inch above the top
of the print head.
2. Turn on the power to the computer, CRT and printer. You
must have a DOS disk or operating system in the boot up
Drive A or DOS must be installed on the hard disk. The
DOS is not provided because of copyrights and incompati-
bility problems.
3. Put the desired main program disk in Drive A.
4. Type in: INPUT, and hit the return key.
5. Make sure the "Caps Lock" key is on.
The program will now ask you to enter the drive that you are using
to place the data on. If using two drives enter B otherwise enter A.
If you are using a hard disk use C.
3.2 Selecting the Desired Treatment Plant Type
You should now see a menu listing the types of treatment plants
available for analysis.' Enter the number which corresponds to the
desired treatment plant type. Note: If you do not see your desired
selection, quit the program and start over from the beginning with the
correct program disk or correct subdirectory.
3.3 Using the Function Menff
The function menu is displayed after the desired treatment plant
type is selected. The function menu has several useful options that
will be explained below individually. Each option allows you to perform
3-2
-------
different operations such as editing, running and entering plant files.
OPTION NO. 1: INPUT A NEW PLANT
This function is the first one that will be used when you initially
run your, desired program. Before selecting this function be sure you
have all the proper information on the plant readily available for entry.
The following sections describe in detail how to answer the questions
that are asked within the input function:
General Questions
The first questions that must be answered deal specifically with
plant influent characteristics.
Entering the wastewater characteristics needed to run the Diagnostic
Operational Modeling Programs is quite easy. There are usually only 13
questions that are asked and some of them don't have to be answered. Some
of the questions will have default values assigned to them if there is no
data available. These variables, and their default values, are as follows:
Z Volatile
TKN
Alkalinity
pfl
P04-P
80Z
30 mg/1
100 mg/1
7.0 S.U.
8 mg/1
A realistic value must be assigned to all other wastewater charac-
teristics for the computer to be able to complete the run.
Note: The computer considers a range of flows beginning at
75 percent of the number entered as "AVERAGE DRY
WEATHER FLOW," which is the first question asked in
this section. This number can therefore be set to
achieve a desired minimum flow in the printout. Any
deviation from actual conditions will, to a certain
degree, affect the accuracy of the model's output at
flows less than the actual average flow.
3-3
-------
Note: The computer considers a range of flows ending at
130 percent of the number entered as "DESIGN FLOW,"
which is the third question asked in this section.
This number can also be set to achieve a desired
ma-r-titnin. flow in the printout. This will also, to
a certain degree, cause some deviation from actual
expected conditions.
AX'l wastewater values should be entered as accurately as possible
to ensure that the mathematical portions of the Diagnostic Operational
Modeling Programs have realistic numbers to work with. If they don't,
the output will have little value.
The following parameters must be entered after completing influent
wastewater characteristics. The format used to describe each required
input parameter is as follows:
"Question": (Range of Answer) "Explanation of Question."
Plant title name: Cup to 40 characters) this will be the
plant name that will appear at the top of each page of
output.
State of: (up to 10 characters)-
Design average flow (MGD): (greater than zero).
Comments: (up to 70 characters) this will be printed at
the bottom of the title page.
Treatment Plant Configuration
This section describes input questions for plant unit processes.
Most treatment plant configurations are listed. Therefore, the actual
input parameters required will be dependent upon the particular program
in use. Note: Questions that require letters for answers need to be
inputted with only uppercase letters.
All questions are to be completed with values that are taken from
the actual plant configuration. For example, when you are asked for a
round clarifier and the plant has only rectangular ones Cor vice versa),
then type in a zero for the type that you don't have.
3-4
-------
CLARIFIER QUESTIONS
Number of round (primary or secondary) clarifiers: (.0-10) do
not exceed 10.
Diameter (.ft) :
Depth Cft) :
Weir length (ft):
(greater than 1)
(greater than 1)
(greater than 1)
REACTOR QUESTIONS
Number of oxidation ditches
Volume (gal)
(less than 10)
(greater than 1)
Number of round reactors
Diameter (ft)
Depth (ft)
(less than 10)
Cgreater than 1)
(.greater than 1)
Number of rectangular reactors
Length
Width
Depth
(ft)
(ft)
(ft)
(less than 10)
(greater than 1)
(greater than 1)
(greater than 1)
REAERATION TANKS
Number of round reaeration tanks :
Volume (MG) :
Number of rectangular reaeration
tanks :
Length (ft) :
Width Cft) :
Depth Cft)
(up to 10)
(greater than zero)
(up to 10)
(greater than zero)
(greater than zero)
(greater than zero)
CONTACT TANKS
Number of round contact tanks
Volume (MG)
Number of rectangular contact
tanks
(up to 10)
(greater than zero)
(up to 10)
3-5
-------
Length (ft)
Width Cft)
Depth (ft)
Cgxeater than zero)
(greater than zero)
(greater than zero)
TRICKLING FILTERS
Primary or Secondary fliter(s) or ABF towers
Media type :
Rock * RK
Stacked plastic - SF
Packed plastic - PP
Enter a two letter code
(redwood for ABF towers)
(any of the above 2 letter codes)
Constant flow / Constant recirculation rate / Percent flow (CF/CR/Pf):
(any of these 2 letter codes)
Number of filters
Filter diameter (ft)
Filter depth (ft)
One of these will appear
Constant flow (gpm)
Recirculation rate (gpm)
Percent of influent over
filter (Z)
(up to 10)
(greater than zero)
(greater than zero)
(greater than zero)
(greater than zero)
(greater than zero)
ABF TOWERS ONLY
Round or Rectangular (RO/RE)
Number of towers
Tower length (ft)
Tower width (ft)
Tower depth (ft)
Flow rate (gpm)
(select a 2.letter code)
(up to 10)
(greater than zero)
(greater than zero)
(greater than zero)
(greater than zero) or recircu-
lation rate (gpm):
(greater than zero)
SLUDGE DIGESTION QUESTIONS
Type anaerobic or aerobic
Sludge thickening
If you said "Y" for yes, then type
(AN/AE) type in only one of
these two letter codes
(Y/N)
Cup to 40 characters)
3-6
-------
AEROBIC QUESTIONS
Number of digesters : (.up to 10)
Volume of each in gallons : (greater than zero)
ANAEROBIC QUESTIONS
Number of primary digesters
Volume Cgal)
Digester heated (Y/N)
Digester mixed (Y/N)
Number of secondary digesters
Volume for digester #(x)
(.less than 10)
(greater than 1)
(Y/N)
(Y/N)
(.less than 10)
(greater than 1)
Note: If you have ten units or more, then you can get reasonable
results by combining the total volume of all units and
entering it as one large unit.
The last question asks you for the name under which you wish to
save the plant's data. You can use up to 8 characters but 'do not use
any special characters such as colons, commas or spaces. This will be
the data's file name.
After you have finished with these questions then you can proceed
to either the RECALL/EDIT option or the RUN MATHEMATICAL MODEL option.
You may choose the edit option if you typed in a bad entry or you may
wish to change a certain parameter without retyping in the entire plant.
OPTION #2: RECALL/EDIT A NEW PLANT
This section will allow you to change the previously entered data
from Option #1 with very little effort.
You will be asked first for the plant name to be used. This would
be the name that you typed in when you entered the plant. If you can
not remember the name, then hit the.return key. The program will list
the directory of the disk with the data files.
After you have typed in the proper name, the program will display
the EDIT MENU. If the menu isn't on the screen, then either you need
to check the disk drive for a possible problem or you typed in a plant
3-7
-------
name that is not on the disk. If this occurs, and the program halts
type in: input , and you can start the program over.
THE EDIT MENU
The edit menu has several options that allows you to edit data
within certain sections of the input routine. For example, if you
had to change the size of a reactor, you would type the option number
that corresponds to the reactors on the menu. Then you would be asked
the reactor questions which are .exactly as they appeared when you first
entered the plant. After you have selected one of the options and
reentered the data, you will be returned to the EDIT MENU again. When
you finish editing the pla"t, then choose the option number that says
"SATE." This option will save the new data back onto the disk. The
program will ask you for the file name that you want to save these new
changes under. If you choose the same name as you typed in to recall
the data, then the program will purge (replace) the old data with the
•
new. If you choose a new plant name, then the program will save the
changed data in a separate file, but still keep the original data file
Intact. Use this procedure if you wish to retain the old plant data.
After you have typed in the plant name to save the data, you can
choose the option that says "RETURN TO MAIN MENU" which will return you
to the function menu. It will make sure that you have stored your
changes. If you do not like the changes you have made, you can either
change them again or return to the main menu without saving the changes.
OPTION #3: RUN MATHEMATICAL MODEL
This option runs the diagnostic calculations. After you choose
number three, the program will load from the disk the routines needed
to generate the calculations.
The program will ask you for the drive that the data is stored on
(for verification). Then it will ask you for the plant name to be used.
This would be the name under which you stored the plant's data. If you
do not remember the name, then hit the return key. The program will
list the disk's directory so that you can see the names of the files.
3-8
-------
The program will ask for a new number. This can be any number you wish,
it is only printed on the title page of the output and has no meaning in
the calculations. It is only used as a reference to distinguish between
different runs.
The program will now load in the plant's data file and run the
mathematical model.
OPTION #4: RETURN TO MAIN MEND
This option does exactly what it says...it returns you back to the
main menu. Be sure that you save the corrections first, otherwise they
will be lost and you will have to retype the corrections.
3.4 Deleting Files
To delete the unwanted files from a disk follow these directions:
1. First, exit from any program you are running.
2. Place the disk from which you want to delete the files
in Drive A, or C if using a hard disk. Type in A:
or C:.
3. Type in: DIE
4. Hit the return key.
5. Find the exact name of the file that you want to delete.
6. Perform the following:
- Type in: DEL
- Hit the space bar, and then type in the file name
- Type in .DAT Immediately after the file name
7. Hit the return key.
You can repeat these instructions if you wish for other files.
The directory displays more information on a disk than just the
file name. An example of just one file would look like this:
EXAMPLE U U U DAT U U U U U 1265 8-25-61 5:00a
EXAMPLE is the name of the file, DAT is the extension. The
number, e.g., 1265 is the number of bytes in the file which is followed
by the date and time of its creation.
3-9
-------
CHAPTER 4
APPLICATION AND THEORY
INTRODUCTION
This section describes some of the theory utilized in development
of the programs. A better understanding of the programs will allow more
meaningful application as well as better results through judicial use.
The following sections will discuss all of the input and output parameters
as to their meaning and derivation. Careful study of this section will
help the user when analyzing a treatment system.
INPUTTING WASTEWATER CHARACTERIZATION DATA
First, it is assumed that the wastewater is typical domestic wastes
or at least behaves as a domestic waste. It is also assumed that the
wastewater is relatively fresh, characterized by a dissolved and un-ion-
ized sulfide concentration of lass than 2 mg/1.
If extensive long term data is available then it is recommended
that this data is carefully examined for seasonal variation. If seasonal
variations are apparent then the system model should be evaluated by
season and not annual averages. Examples of significant and common
variations are temperature and organic or BOD loading. A real and
typical case of this type of variation involved a mountain community with
several ski resorts. Annual average data indicated that the plant would
produce an acceptable effluent. During the winter months the temperature
was less than 10*C and the BOD averaged 310 mg/1, whereas in the summer
months the temperature was 20°C and the BOD was only 150 mg/1. The plant
would not function during the winter due to low temperatures of the
activated sludge and high organic loadings. Further, during the spring,
hydraulic flows increased substantially during snow melt. The plant
accordingly was modeled for winter conditions, spring break-up and
summer conditions. The predicted results closely matched the actual
4-1
-------
performance and of course the results indicated the need for expansion
and modification during the winter and ski season.
The following is an explanation of the wastewater characterization
data and sensitivities involved with each parameter.
AVERAGE DRY WEATHER FLOW, MGD
This means the average daily flow for the plant for a specific
period. Care should be taken to eliminate abnormal conditions such as
storm flows that occur infrequently. The average daily flow is used in
calculating organic and solids loadings as well as determining hydraulic
residence time, surface loadings and weir loadings. It is an important
parameter.
PEAK DAILY DRY WEATHER FLOW, MGD
Peak Dry Weather Flow is the average daily peak flow that occurs
for a four to six hour duration during the day. It is used in determin-
ing the peak flow factor for all flow regimes on the printout. As an
example, if the average dry weather flow was 1.5 mgd and the peak dry
weather flow was 3.00 mgd, the peak flow factor would be 2.0. This
factor is used when computing the performance of the final clarifiers in
all systems. It is a very important parameter.
DESIGN FLOW MGD
Design flow is exactly as stated which is the intended design
capacity of the plant. Both the average and design flow can be skewed
or adjusted to increase the sensitivity of the diagnostic models. This
will be explained in a later section.
INFLUENT BOD, MG/1
This value is the average BOD that the system sees over a given
period of time. The model assumes that this value will increase by about
ten percent due to recycle flow. For most accurate results the standard
deviation should be less than 15Z of the mean or inputted value. This
is an important parameter.
4-2
-------
INFLUENT TSS, MG/1
This is the average value of the total suspended solids (filtered
residue). The same concepts and concerns for BOD values mentioned
above apply to the TSS values.
INFLUENT VSS, Z
This is the .average percent volatile solids determined by laboratory
analysis. It is a significant parameter when evaluating activated sludge
(suspended growth) systems. And a low volatile content or high inorganic
content "ill influence the "ayimmn mixed liquor capacity in a suspended
growth system. It is not sensitive in fixed film systems such as with
trickling filter and rotating biological contractors. In both cases it
does influence sludge production because the non-volatile or inert flux
to the system for the most part becomes a part of the sludge production.
The volatile content varies geographically. Unfortunately this determ-
ination is not always made by operators therefore a default value of
80Z is used if data is not available. Volatile content will vary from
65Z to 90Z. This parameter is not as important as others previously
mentioned.
TEMPERATURE °C
This is the average value of the wastewater temperature during the
examination period. It is an extremely important value and the standard
deviation should be less than 20Z of the mean value. Temperature is used
In determining the optimum compaction in primary sludge, and for determin-
ing kinetic rates in suspended and fixed film systems. This is a very
important parameter.
TKN, MG21
This is the average total Kjeldahl nitrogen in the influent which
is the total nitrogen in the trinegative state. It includes organic and
ammonia nitrogen. Some treatment plants determine only the ammonical
nitrogen. If this is the case for the plant that you are examining, then
use that value. Unfortunately many plants do not determine influent
4-3
-------
nitrogen species at all. If this occurs then a default value is built
into the computer system. This is not an important parameter in any of
the models. All of the diagnostic models assume that there are adequate
quantities of nitrogen to satisfy the nutrient requirement for good
biological growth. If the nitrogen values are known in activated sludge
systems then the model will predict the species and quantity. A negative
value will indicate a nutrient deficiency.
ALKALINITY, MG/1
Alkalinity is not an important input parameter and is no longer
used in the diagnostic models. It was originally intended to be utilized
in predicting pH depressions but found to be inaccurate.
pH, UNITS
pH is not an important input parameter. It is for reference' purposes
only.
P04-P, MG/1
This is an average value of the phosphate concentration expressed
as phosphorus. It is not an important input parameter since all the
models assume an adequate supply for nutrient requirements. Negative
values predicted in activated sludge systems indicate a phosphorus
deficiency in the wastewater.
PLANT CONFIGURATION AND DIMENSIONS
The first input values in this section are average design flow
and peak wet weather flow. They are for reference purposes only and
are for notation purposes when average and design flows in the above
section are skewed by the model user.
The remaining input values for various unit processes are of course
extremely important. They are the basis for predicting process per-
formance. The one exception to this is the secondary digester volume
which is for reference purposes only.
4-4
-------
COMPUTER PRINTOUT FORMATS, GENERAL
All of the diagnostic programs print out twenty flow regimes based
on values inputted in the wastewater characterization section. The first
flow starts with 0.75 times the inputted average dry weather flow value
and stops at 1.3 times the inputted design flow value. The program user
can input any realistic values desired to increase the sensitivity or
expand the flow regimes. As an example, if the user wished to increase
the sensitivity of the diagnostic evaluation of a treatment plant that had
an average daily flow of 1.00 mgd, the average and design flow could be
inputted as 1 mgd and the printout would develop 20 predictions from 0.75
to 1.3 mgd. This is the reason for repeating the design average flow in-
put under the plant configuration section. When examined at a later date
and these two values don't match, then the user knows that the first values
were probably skewed to develop more data within a desired flow regime.
The left hand column of all sheets depict the plant flow as described above
and will not be discussed again.
PRIMARY SYSTEM PERFORMANCE AND LOADINGS
Each heading on the printout will be discussed separately excepting
the flow data which was previously discussed. Derivation of each value
will be explained in detail or conceptually if too complex for the
level of this text.
CLARIFIER SURFACE, GPDSF
The primary clarifier surface loading is computed in gallons per
day per square foot.. The total surface area is computed based on data
inputted in the primary clarification section of the data input section.
This is merely a calculated value and is used in predicting the BOD and
TSS values of the primary clarifier effluent. High, low and normal
values for surface loadings are depicted in Appendix E of this manual.
WEIR LOADING, GPD/FT
The primary clarifier weir loading expressed in gallons per day per
foot is a calculated value based on the total weir length inputted in
the primary clarifier input section. This value is not used in the
4-5
-------
performance prediction. Experience indicates that weir loading has
little or no effect on primary clarif ier performance when the surface
loadings are adequate. There are of course exceptions to every rule,
and th« high, low and average values should be examined in Appendix E
Of this
DETENTION TIME, HRS
This value is the calculated detention time at average flow con-
ditions. This calculated value is not used in the primary clarif ier
performance prediction. Experience indicates that surface loading
with adequate clarif ier depth are the factors that significantly affect
primary clarif ier performance. Primary clarifiers should have an
average depth of 8 feet or greater. Appendix E indicates high, low
and average values for detention time.
PERCENT REMOVAL BOD, PERCENT REMOVAL TSS
These are predicted values based on surface loading. They are
probably the most inaccurate predictions in the entire model system
because they are based on correlation factors rather than sound
scientific principles. Experience indicates that there are no sound
scientific principles that can be strictly applied to gravity treat-
ment of raw sewage. Indeed there are scientific principles that apply
to discrete particles of specific densities, drag coefficient, size,
density of fluid media, etc. However, in primary clarification of raw
sewage one is dealing with a manifold of different particle sizes,
density, etc. First attempts to correlate primary clarif ier perform-
ance did not produce good results. Surface loading appeared to be the
most promising. Systems that operated at temperatures of less than
20°C and described as "relatively fresh" seemed to have the best cor-
relation. Examining this concept closer revealed some obvious facts.
The more septic a sewage becomes the more putrefaction and liquefaction.
The model assumes that a reasonably fresh sewage is being treated. An
experienced operator can usually determine a septic sewage by its color.
In secondary systems where the primary performance does not match the
predicted performance within reasonable limits then the influent BOD
4-6
-------
and TSS values can be Increased so the primary effluent closely matches
the actual or measured values. Before this is done be sure that this
approach is valid. Often plant staff will report grab samples collected
during the day. These reported values will obviously be high compared
to composite samples. In the simplest arithmetic terms the percent BOD
removal is calculated using the following equation:
Z BOD removal •
E- (0.98)(SL)"|
350 -I- SL J
_ _ X 100
Where:
SL equals .the average surface loading in gallons per square foot
per day.
The percent TSS removal is calculated using the following equation:
Z TSS removal - 1 - (0.98)(SL)
748 + SL X 100
Where:
SL is the average surface loading in gallons per square foot
per day.
If the user decides to increase or even decrease the influent values
for BOD and TSS to achieve closer values to the verified clarifier per-
formance this will change the predicted sludge production values.
PRIMARY CLARIFIER EFFLUENT BOD AND TSS, MG/1
Both of these values are calculated from the removal efficiency
predictions described above. As an example, if the BOD and TSS removal
efficiencies were 36Z and 46Z and the influent BOD and TSS concentra-
tions were 210 mg/1 and 235 mg/1 respectively, the primary clarifier
BOD concentration would be as follows:
(100 - 36)(210)(0.01) - 134.4 mg/1
The primary clarifier effluent TSS concentration would, be as follows:
(100 - 46)(235)(0.01) - 126.9 mg/1
Note: Appendix G is a sample printout of a primary treatment plant
diagnostic. At a flow of 6.05 the predicted removals are 36 and 46
percent for BOD and TSS, respectively. Note that the primary effluent
BOD and TSS predictions in the Appendix vary slightly from the above
calculations. This is due to different rounding procedures and any
4-7
-------
errors that occur in rounding are well within the limits of prediction
accuracies.
PRIMARY SLUDGE PRODUCTION, LBS. TSS
This is a calculated value based on input and predicted values.
Appendix 6 indicates a total sludge production of 5474 Ibs. per day at
a flow of 6.05 mgd. The sludge production is calculated as follows:
(MGD)(inf. TSS - Eff. TSS)(8.34) - Ibs. of sludge produced per
day, substituting the calculated and predicted values.
(6.05)(235-127)(8.34) - 5,450 Ibs.
Note the slight difference of 24 Ibs. which is not significant.
PRIMARY SLUDGE PRODUCTION, LBS. VSS
This is a calculated value based on input and predicted values.
Appendix G denotes an influent TSS of 235 with a volatile content of
83Z. It is assumed that volatile content is the same for primary
clarifier influent and primary clarifier effluent. Analysis of primary
systems indicates that this value does differ slightly, however, the
difference is-normally not significant. The Ibs. VSS is calculated
as follows:
(Z Volatile)(0.01)(Ibs. TSS) • Ibs. volatile solids
substituting the values in Appendix G.
(83)(0.01)(5474) - 4,543.4 Ibs. volatile solids
Again note the slight difference in the total pounds due to rounding.
This value is significant when performing a digester analysis.
PRIMARY SLUDGE PRODUCTION, Z SOLIDS
This is a predicted mmr-tnmm value based on temperature. Some treat-
ment facilities have gravity thickeners where primary sludge is thickened
prior to pumping to digestion or dewatering. In the above case the pre-
dicted value would not apply because the operational Intent would be to
pump a relatively thin sludge from the primary clarifiers to the thick-
ener. Further, often the piping configuration and the type of sludge
pumps will not allow thick sludge to be pumped from the primary clarifier.
4-8
-------
This value is the maximum achievable concentration under idealized
conditions. It also assumes that the raw sewage is relatively fresh and
not septic.
Experience indicates that maximum primary sludge concentrations
are affected by temperature. In extremely cold climates the rate of
biological activity is substantially reduced therefore sludge can be
retained in a primary clarifier for longer periods of time and conse-
quently greater concentrations can be achieved. As the temperature
increases the rate of biological activity increases, therefore, putre-
faction and subsequent liquefaction occurs more rapidly resulting in
lower concentrations of primary sludge. The primary sludge concentra-
tion is, therefore, predicted as a function of influent temperature.
The equation is as follows:
Sludge Concentration Z - L_1._042V ' \ 6.20
Appendix G indicates a temperature of 22"C therefore substituting this
value:
. - [To42(20-2i[j 6.2 - 5.71%
Z Cone
The program limits the maximum concentration to 8.52 even though higher
concentrations at low temperatures have been observed and consistently
achieved. This is the exception rather than the rule.
PRIMARY SLUDGE PRODUCTION, GPD
This is a calculated value of gallons of sludge to be pumped from
the primary clarifier each day based on predicted and input values. The
calculation is as follows:
(Ibs. TSS)(0.01)/(ZSOL)(8.34) « GPD primary sludge
Substituting calculated and predicted values from Appendix G at a flow
of 6.05 mgd
(5474)(100.0)/(5.71)(8.34) - 11,494.8 Ibs. or 11,495 Ibs.
of primary sludge.
4-9
-------
MASS BALANCE
In wastewater treatment, matter is neither created or destroyed,
therefore, each unit process in a wastewater plant should balance to
a reasonable degree. A primary clarification system is not an excep-
tion. Using the data in Appendix G the influent TSS is calculated in
pounds per day at a flow of 6.05 mgd. This calculation is as follows:
(Flow, mgd)(Inf. TSS)(8.34) - Total Ibs/day
Substituting the values
(6.05)(235)(8.34) - 11,857.4 Ibs. per day
Using the same equation, the Ibs. of TSS in the primary clarifier
effluent is calculated by substituting the influent TSS with the pre-
dicted primary clarifier effluent TSS.
(6.05)(127)(8.34) - 6,408 Ibs. TSS in effluent
Note on Appendix G that the predicted sludge production is 5474 Ibs. per
day.
The Ibs. of sludge produced is added to the Ibs. of TSS in the
primary clarifier effluent
(5474 Ibs. sludge) + (6408 Ibs. TSS in eff.) -
11,882 Ibs. total which should equal the Ibs. TSS in the
Influent which is 11,857. They match within three significant figures
or within 25 Ibs. When evaluating actual plant data the same approach
should be used. A well operated plant with good data should balance
within 20 to 25 percent. It is rare that a system will balance perfectly
due to inaccuracies in flow measurement, sampling and analysis. Also
when a significant amount of recycle is involved this should be
included with the Ibs. of TSS in the influent.
The application and theory with respect to primary clarification
applies to all models that contain primary clarification. The format
and presentation may differ slightly but the theory and application is
the same.
4-10
-------
ACTIVATED SLUDGE SYSTEMS MODEL AND LOADINGS
ADDITIONAL INPUT VALUES
In addition to the previously mentioned input values, other param-
eters or limits are required as well as reactor and clarifier dimensions
along with the number of units.
The two additional input parameters are the in«Hnmm mixed liquor
suspended solids (MLSS) in mg/1 and the maximum mean cell residence time
(MCRT) in days. These are mflit^"""" limits and will function as a limit
only if the system is capable of achieving the inputted maximum value.
Also one of these values will normally predominate. As an example, con-
sider a conventional activated sludge plant at design conditions. Assume
the ""»-*tnp"n MLSS is set at 1,000 mg/1 and the MCRT is at 50 days. The
MLSS value will control and a 50 day MCRT will never be approached. More
will be explained later.
REACTOR DIMENSIONS
The program asks for both rectangular and circular reactors -as well
as the dimensions. After these values are inputted, the computer calcu-
lates the total volume. Only the volume is used in subsequent calculations.
Because the models are designed for domestic wastes, the reactors are
assumed to be completely mixed. In domestic wastes there is little
difference between plug flow and complete mix because of the high substrate
utilization rate.
CLARIFIER DIMENSIONS
The program asks for both rectangular and circular clarifier dimen-
sions as well as weir length. These dimensions are critical since Che
depth and total surface area are used in the algorithms. The weir length
is used to calculate the weir loading and not used to predict performance.
Also with clarifiers of different sizes, it is assumed that the flow is
proportionally split as a function of surface area.
MAXIMIZING THE REACTORS AND CLARIFIERS
First, it should be noted that the algorithms used in the performance
prediction are proprietary and will not be completely revealed in this
document. However, enough information will be rendered to foster a
4-11
-------
functional understanding of the system. This discussion applies to all
activated sludge systems.
The activated sludge model starts with either the influent or pri-
mary clarifier effluent flow and associated characteristics such as BOD,
TSS, VSS, NH--N, PO,, temp., etc.
First the BOD is temperature adjusted by using the factor 1.03
where t is the wastewater temperature in degrees Celsius. As an example
if the BOD were 200 mg/1 and temperature 24°C then the adjusted BOD
would be:
(200) x [1.03(20"24)] - 178 mg/1
This value is used in the kinetic analysis because the rate of reactivity
varies as a function of temperature. The F/M ratio or substrate removal
velocity is then determined based on the maximum mixed liquor value
inputted by the user. The substrate removal velocity (Ibs. of BOD
removed per Ib of cell mass, .MLVSS) is assumed to about equal the food
to microorganism ratio (Ibs. of BOD applied per Ib. of cell mass MLVSS).
In a well-operating plant this is true. In a poorly operating plant it
is not necessarily true but not a sensitive value compared with high TSS
values in the effluent.
For the first iteration it is assumed that the MLSS concentration
is equal to the MLVSS concentration. This, of course, is not true.
However, it forces a loop that will eventually balance. The substrate
removal velocity is determined as follows:
q - _§£_
' *19
Where:
q * substrate removal velocity (Ibs BOD removed/lb of MLVSS/day)
So - the temperature adjusted reactor influent BOD
X- - the ma-sHjmnn or adjusted MLVSS in the reactor in mg/1
9 * the hydraulic residence time in the reactor without
recycle flow (days)
As an example if the maximum MLSS was set as 2,500 mg/1 the X. would be
set at 2,500 mg/1 knowing that X. is MLVSS and not MLSS. The mean cell
4-12
-------
residence time is then computed with the following formula:
9.
c Y - Kd
q
Where:
9 - MCRT in days
7 • Net cell growth and assumed as a constant, therefore
Y * 0.6 Ibs of cell mass produced per Ib of BOD destroyed.
q - The substrate removal velocity determined in the preceding
equation.
Kd • Is the endogenous respiration rate in days and determined
as a function of the substrate removal velocity, where
Kd - °'12q
.23 + q
After the mean cell residence time is computed then the total MLSS is
computed by adding the MLVSS (X.) with the inert concentration accumulated
as a function of the MCRT. The following equation is used:
F9 (X - X )
R . __£_2 J - R mg/1
1 -6
Where:
R. * Reactor inert solids concentration in mg/1
F • The plant flow in mgd
9 * The mean cell residence time in days
X * The reactor influent TSS in mg/1
X - The reactor influent VSS in mg/1
R * The reactor volume in gallons
The total MLSS is then computed as MLSS - X. •*• R.
Obviously if the inputted maximum mixed liquor was originally set
as equal to the MLSS, the computed MLSS will always be greater than the
entered or desired MLSS.
The conditional statement determines whether the MLSS computed value
is equal to or less than the inputted maximum value. In the first
4-13
-------
iteration obviously it is not, unless the inert fraction of the influ-
ent TSS is zero. If the computed MLSS value is greater than the inputted
maximum value, then 100 mg/1 is subtracted from the preset 3C. value. If
it is not equal to or less than, then 100 mg/1 is deducted from the pre-
set X. value (i.e., the originally inputted MLSS value). This loop
continues until the computed MLSS value is equal to or less than the
desired MLSS value.
When the above occurs then the maximum compaction concentration is com-
puted. This is a proprietary computation, and is a function of the mean
cell residence time and temperature. If the ultimate compaction is com-
puted to be greater than 10,000 mg/1 then the compaction is set at
10,000 mg/1 per liter. The reason for this is simply that ultimate compac-
tions of greater than 10,000 mg/1 are normally not consistently achievable.
After the ultimate compaction concentration is determined then the
depth of blanket (DOB)'in feet is determined. The depth of blanket is
measured from the surface of the clarifier down to the interface of the
settled activated sludge. The algorithm sets the maximum height of the
blanket to six feet, therefore, the depth of blanket (DOB) must be equal
to or more than six feet. The depth of blanket is computed using the
following equation:
*1
DOB » d (1 - _) where
xr
Where: DOB - depth of blanket, feet
d - average clarifier water depth in feet
X. * computed mixed liquor concentration in ing'1
X " computed ultimate compaction of the activated sludge
r in mg/1 which will be 10,000 mg/1 or less.
If the computed DOB is six feet or greater then the algorithm continues to
the next series of computations. If the DOB is less than six feet, a con-
ditional statement directs the procedure to the first part of the program
and again reduces the MLVSS by 100 mg/1, then proceeds through all of the
previously mentioned computations and recomputes the DOB, and will continue
to run in this mode until the DOB is six feet or more. Obviously if the
final clarif ier depth is inputted as six feet or less the program will not
run.
4-14
-------
After the depth of blanket is set the algorithm continues to pre-
dict the effluent BOD and TSS. This is a proprietary equation. The
equation considers the mean cell residence, the average daily flow, the
peak flow is assumed to be a. six hour duration. Temperature is also
considered. The equation predicts the effluent TSS and assumes that the
effluent Z VSS is about equal to Z MLVSS.
After the effluent TSS is determined then the effluent BOD is cal-
culated based on 0.70 times the effluent VSS plus an assumed soluble
BOD which is determined as a function of the mean cell residence time.
Each heading on the printouts will be discussed separately excepting
the plant flow data which has been previously explained and the derivation
of values previously explained in this section. Additional input values
are also discussed.
ADDITIONAL INPUT PARAMETERS
In addition to the input values previously discussed, the maximum
MLSS and HIST are required under .the wastewater characterization section.
The lesser of these values -will predominate in the algorithms. As an
example if the «a-»-»™™ MLSS value is inputted as 5,000 mg/1 and mayi'miim
MCBT is inputted as 8 days. In a conventional system rarely will be
mixed liquor exceed 2,500 mg/1 at design flow. In this case the system
will be examined at a mixed liquor equal to or less than 5,000 mg/1.
After the system is balanced, then the MCRT is examined and if greater
than 8 days, the mixed liquor will be lowered in increments of approxi-
mately 100 mg/1 until the MCRT is equal to or less than eight days. Con-
versely, if the mixed liquor is at 1,500 mg/1 and the MCRT is set at 35
days in an extended aeration plant the 1,500 mg/1 value will probably
control since most extended aeration plants are designed to operate at
mixed liquor concentration in excess of 3,000 mg/1.
Additional input values include the final clarifier configuration and
the reactor or aeration basin configuration. The exact dimensions of the
final clarifiers are essential since the performance prediction is based on
the clarifier surface loading and the side wall depth. The reactor config-
uration is not critical but the resultant volume is critical. The algorithm
considers only the total volume and assumes a completely mixed system.
4-15
-------
BIOLOGICAL PERFORMANCE SHEETS
MAXIMUM MLSS
This is the ^air-timim mixed liquor suspended solids in mg/1 as
determined or controlled by the blanket depth in the final clarifier,
the inputted maximum mixed liquor, or the inputted mean cell residence
time. Even though these values are displayed to the nearest mg/1 they
are only accurate to the nearest 100 mg/1. The nearest mg/1 value is
displayed in order to show change in MLSS even with the slightest flow
change.
MLVSS
The method of computing this value has been explained. It repre-
sents the fraction of cell mass in the system and controls the mean cell
residence time. Obviously it is a critical value. Other than maximum
MLSS and MCRT constraints inputted by the user, the % 7SS in the influent
is a critical value. The I VSS should be known, if not the 80Z default
value may be used realizing that this may affect the entire cell mass
estimated for the system.
F/M
This is the food to microorganism ratio expressed as Ibs of BOD
applied per Ib of MLVSS (cell mass) per day. In the algorithm the F/M
ratio is considered equal to the substrate removal velocity, q, expressed
as Ibs of BOD removed per Ib of MLVSS (cell mass) per day. This is not
exactly correct however when examined as total BOD in the reactor versus
soluble BOD in the effluent, there is an insignificant difference between
F/M and q in a treatment plant that is performing reasonably well.
MCRT DAYS
The method of determining the mean cell residence time in days has
been previously discussed in detail. The computer printout is to the
nearest day, therefore, at times the MCRT has not changed more than one day.
When evaluating a treatment plant it should be noted that the MCRT used in
the diagnostic program is based on the reactor only. Many operators
will determine and control their system based on MCRT determined by
using the reactors, final clarifier and even sludge piping, therefore,
4-16
-------
MOST values may differ from the computer printout. The computer printout
and associated equations are based on a kinetic analysis. In day to day
operations, it makes little difference as to how the MCRT is computed as
long as it is consistent.
SVI
SVI is the sludge volume index expressed as grams per 100 mis. It
is calculated from the computed ultimate compaction value (X ) expressed
in mg/1. The value is computed as follows:
6
SVI - •= - « grams/100 ml
r
Note in the preceding discussion the ultimate compaction has been
limited to a maT-tunm concentration of 10,000 mg/1, therefore, the mini-
mum SVI value will always be 100 g/100 ml.
RAS, MGD
This is the average return activated sludge flow in million gallons
tivat
- mgd
per day. The return activated sludge flow (F ) is determined as follows:
»
r X - X,
r T.
Where:
F - the average daily flow in mgd
X. - the MLSS concentration in mg/1
X - the ultimate compaction in the final clarifier in mg/1
This equation is based on a simple mass balance around the final clarifier
and biological reactor. The pounds of mixed liquor introduced to the
final clarifier must equal the pounds discharged in the effluent plus the
pounds removed. The total pounds discharged and removed is the sum of
the solids leaving with the effluent, the solids being returned to the
reactor, and the solids wasted.
The equation was previously mentioned for recycle control, however,
the rationale is:
4-17
-------
F » the plant flow, mgd
F - the return activated sludge rate, mgd
X. * the mixed liquor suspended solids, milligrams per liter
X • the return activated sludge concentration, milligrams
r per liter
X. • the suspended solids In the final clarifier effluent,
milligrams per liter
Pt - total pounds leaving the activated sludge tank Cor
removed in the clarifier)
Then: (F+F ) (X.) (8.34) » P - total pounds introduced to
final clarifier
Also: (Fr) (X ) (8.34) + (F) (Xj) (8.34) - totals to
be removed from the clarifier or - P , therefore
(F + Fr) (X^ (8.34) - (Fr) (Xr) (8.34) + (F) (X2) (8.34)
(F + Fr) (X^ - (Xr) (Fr) + (F)
(F) (X^ + (Fr) (X^ - (Xr) (Fr5 + (F)
(F) (X^ - (F) (Xj) - (X ) (Fr) - (Fr)
F
F
To simplify the calculation, the effluent suspended solids concentration
has been eliminated from the diagnostic model because it has little
sensitivity when the mass of mixed liquor and RAS are considered.
HAS MG/L
This is the idealized return activated sludge concentration computed
using the ultimate compaction as previously discussed. It is assumed
that this concentration is obtainable. Often the RAS concentration will
4-18
-------
be considerably different from actual practice. Most commonly, the
actual concentration is substantially less than the predicted value.
This is often due to excess recycle pumping or poor compaction due to
filamentous growths in the system.
WAS. LBS/DAY
This value is the waste activated sludge in pounds per day. This
is a calculated value based on the predicted performance parameters.
The WAS is computed as follows:
R
WAS - -2-
9
c
Where:
R * Total reactor mass In pounds
9 - Mean cell residence time in days
c
DETENTION TIME, HOURS OR DAYS
This is the reactor detention time determined in hours and days.
The detention time does not include the RAS or any recycle flows. It
is for reference purposes only and has little significance in most con-
ventional plants. In general the retention time should be greater than
2 hours for substrate uptake and catabolism.
LOAD, LB BOD/1000 FT3
This is the reactor loading expressed in pounds of BOO applied to the
reactor per 1,000 cubic feet of reactor volume. It is a calculated value
and not utilized in the prediction algorithms. It is for reference pur-
poses only and a general indicator as to the loading and capacity of the
treatment plant. Appendix E indicates loading ranges for high, low and
normal loadings.
OUR, MG/L/HOUR
This is the average oxygen uptake rate of the system under the
specified flow conditions. It is expressed as mg/1 per hour of oxygen
consumed by biological metabolism in the biological reactors. It is not
respiration rate which is expressed as milligrams of oxygen used per gram
4-19
-------
of volatile suspended solids (cell mass) in Che reactor. Actual in-
plant uptake rates can be made and compared with the predicted value.
They should be reasonably close if the mixed liquor VSS and reactor
influent BOD are close to the model prediction values. The oxygen uptake
rate is computed from the total oxygen demand as follows:
• mg/l/hr
r
Where:
0. - Total oxygen demand or requirement in Ibs
per day
7 - Reactor volume in MG
200 - Constant - (8.34) (24 hrs) - 200
0, ROD. LBS/DAY
& ^""^•"~~^~~^~
This is the total oxygen required in the reactors for metabolism
expressed in pounds per day. First the ultimate oxygen demand is deter-
mined by multiplying the total pounds of BOD per day introduced to the
reactor by a factor of 1.42. This approximates the 20 day BOD for carbo-
naceous and nitrogenous oxidation. Then the Ibs of cell mass is subtrac-
ted from this value which approximates the BOD of the wasted volatile
material. The expression is as follows:
0. - 1.42/S - W \
d ( o cj
Where:
0, - Ibs of 0. required per day in the reactor
S * Ibs of BOD per day introduced to the reactor
W * Ibs of cell mass (VSS) wasted from the system
each day
FINAL CLARIFIES PERFORMANCE AND
EFFLUENT CHARACTERISTICS
DETENTION. TIME. HOURS
This is the detention time of the clarification system expressed in
hours. It is a calculation based on input values and not used in the
process algorithms. It is for reference purposes only. It can be of
benefit in diagnosing treatment plant problems, especially for
4-20
-------
underloaded facilities. As an example, if the detention time in a system
was six to eight hours, denitrification and/or septicity could occur and
subsequently cause a high solids flux in the effluent.
DOB. FT
This is the depth of the sludge blanket in feet measured from the
surface of the final clarifier to the interface of the blanket. It is a
predicted value and its derivation is discussed in the previous section.
In practice, or when comparing field measured blanket depths with predicted
depth from the model, the measured depth should be equal to or greater than
the model prediction. If the blanket is higher than predicted (i.e.,
actual DOB would be a smaller value) then the recycle rate and/or sludge
compaction is inadequate.
EFF. BOD. MG/L and EFF. TSS. MG/L
This is the predicted value of the final clarifier effluent expressed
in mg/1. The derivation excluding proprietary equations has been pre-
viously presented. Any predicted value of BOD or TSS that is less than
5 mg/1 is presented as <5 mg/1. The accuracy of these predicted values
is greatest between 20 and 40 mg/1. Predicted values of less than 10 mg/1
and greater than 60 mg/1 are less accurate.
ETF. NH^. MG/L and EFF. NOj. PO^.. MG/L
These values are predicted levels of either ammonia nitrogen or
nitrate nitrogen expressed as milligrams per liter of nitrogen. The cell
mass in an activated sludge system contains about 10% nitrogen and 2%
phosphorus. The nitrogen or phosphorus in the wasted sludge is subtracted
from the total N or P in the reactor influent and the resultant is expres-
sed as N or P in the effluent in milligrams per liter. For nitrogen con-
centration the equation is:
N FN - 0.1 F,. X.
. e " F w v
For phosphorus concentration the equation is:
P , FP - 0.02 F. X
1 ~
4-21
-------
Where:
N - the predicted ammonia or nitrate N concentration
6 in the effluent in mg/1
F - Plant flow to the reactor in mgd
F « Waste activated sludge flow in mgd
X - ML7SS concentration in mg/1
N » Total nitrogen concentration in the reactor
influent in mg/1
P • The predicted phosphorus concentration in the
6 effluent in mg/1
P » Total phosphorus concentration in the reactor
influent in mg/1
If the predicted values for N and P are equal to or less than 5 and 2
mgl respectively, then there is a potential nutrient deficiency. If
the values are printed as negative numbers this indicates a definite
nutrient deficiency which will cause poor settling and poor performance.
With regard to NIL. and NO, values, the point where nitrification
occurs and is indicated on the printout sheet is not accurate. The
printout changes from NH- to NO. at about a ten day MCRT. This is
intended to be an indicator showing approximately where nitrification
occurs.
SECONDARY SYSTEM PERFORMANCE
CLARIFIER LOAD. SFC. GPSFD
This is the total surface loading on the final clarification system
expressed in gallons per square foot per day based on average daily flow.
It is a calculated value for reference purposes only. Appendix E shows
high and low loading limits as well as normal loadings.
CLARIFIER LOAD. WEIR GPLFD
This is the weir loading expressed in gallons per day per lineal
foot and is a calculated value based on the total weir length inputted
in the final clarifier input section. This value is not used in the
4-22
-------
performance prediction. Experience indicates that in most plants weir
loading has little or no effect on the final clarifier performance when
the surface loadings are adequate. There are exceptions to every rule,
and high, low and average values should be examined in Appendix E.
Sludge Production
These values for secondary and primary sludge if applicable are
recalculated and tabulated for reference and comparative reasons. Number
of Ibs printed on the primary sheet and the reactor performance sheet may
differ slightly due to rounding errors. The difference is negligible.
Percent Solids
This is the estimated concentration of the combined sludges that is
pumped to the digester. The calculation is based on the percentage of
primary sludge and waste activated sludge and the mean cell residence
time.
GPP - Gallons
This is a calculated value based on the total predicted sludge
production and the estimated percent solids of the combined sludges.
These flows are subsequently used in the digestion analysis if selected
by the user.
VARIATIONS HI ACTIVATED SLUDGE PROGRAMS
Activated Biofilter Systems
The basic process algorithm is the same as described for the activated
sludge system excepting the algorithm includes a modified version of the
fixed film algorithm that gives credit for BOD removal across the bio-
tower.
Contact Stabilization
The algorithms for the contact stabilization programs are the same
for the standard activated sludge systems with the exception that the
algorithm recognizes a biological contactor where substrate assimilation
occurs with minimal metabolism. The contactor is limited to a minimum
F/M 0.6 Ibs of BOD per Ib of MLVSS per day and the reaeration basin is
4-23
-------
limited to a mi-niimnn p/M of 0.1. This is the only significant difference
in the program. The kinetic equations are exactly the same. The nitro-
gen species prediction is also the same except that only a portion of the
flow (HAS) is nitrified in the reaeration basin.
FIXED FILM SYSTEMS MODEL AND LOADINGS
Fixed film systems include trickling filters, rotating biological
contactors (RBC) roughing filters and activated biofilter towers (ABF).
From a biological and kinetic standpoint, they are treated the same and
will be explained in a subsequent section.
ADDITIONAL INPUT VALUES
In addition to the previously discussed input, other parameters or
limits are required as well as dimensions for trickling filters, ABF
biotowers, roughing filters and RBC configurations.
For trickling filters, diameter and depth are required. In addition,
the type of madia must be known. There are three general categories for
the media. These are rock, stacked plastic and packed plastic. The
prediction algorithm is based on the effective surface area of the fixed
film system. The effective surface area for these types of media are
assumed to be 17, 28, and 32 square feet per cubic foot of media,
respectively.
In addition, there are three types of recycle mode options. These
are:
1. Constant recycle. This means in addition to the plant
flow, a constant amount of water is recirculated around
the filter. The constant recycle flow is expressed in
gallons per minute.
2. Constant flow. This means that the filter sees a constant
flow regardless of the plant flow. When inputting this
value be sure that it is at least equal to or greater than
the last flow iteration. The input value is expressed in
gallons per minute. As an example, if design flow value
is inputted as 1.5 mgd then the last flow iteration will
be 1.3 x 1.5 * 1.95 mgd. The constant flow input oust be
4-24
-------
greater than 1.95 x 694.4 » 1354 gpm for all the flow to
pass through the filter. If the inputted constant flow
value is less than the plant flow iterations then the
computer will print "the recirculation rate is negative
beyond this point." The computer will then go to the
next page of the printout and continue to calculate or
predict values to the point of negative flow.
3. Percent of flow. This assumes a certain percent of the
plant flow is recycled around the filter. The input
value is expressed in percent. The percent of flow is
then calculated for each flow iteration. There is a
recycle flow option for each filter including secondary
filters for two stage systems.
For RBC systems other inputs are required. First the manufacturer
and type of drive unit is requested. These two inputs are not used in
the process algorithms at this time. They are for reference purposes
only. At the time of the model development the only RBC systems avail-
able were mechanically driven units. At the present time there is not
sufficient data available to distinguish between the present variations.
Present data indicates that the performance predictions are accurate for
both systems.
The program then asks for the number of process trains and the
number of shafts per train. It then asks for the surface area of each
individual shaft in the process train. These parameters are critical
(trains and surface area) as they are used in the process prediction
algorithm.
For the ABF system, the size of the ABF biotower and type of media
is required. There are only two options available, redwood slats or
plastic media.
PROCESS ALGORITHMS
The process algorithms are based on a modification of the National
Research Council (NRG) equation for trickling filters. Recirculation is
assumed to be directly around the filter elements. Systems that recircu-
late round a clarifier and filter will not work with these programs.
4-25
-------
The reason is that in this type of plant the clarifiers are designed to
accommodate the recycle flow and, therefore, are substantially larger
than conventional clarification systems. For ABF systems, all the return
activated sludge is assumed to be recycled over the ABF tower.
The NRG equation does not address temperature of sewage or the
final clarifier size. The basic NRG equation is as follows:
1 + 0.0085 [/So
VF
Where:
E. « the fraction efficiency of BOD removal for the
system including recirculation. Thirty minute
settling is assumed
S - BOD loading to the filter in Ibs per day
7 - the volume of the filter in acre feet
F • the recirculation factor expressed as:
10
Where:
Q - the recirculation flow
Q * the plant flow
The basic equation has been modified as follows:
,(20-tK
S has been changed to S (1.03
o o
to compensate for temperature of the wastewater
has been adjusted for type of media and its effective
surface area.
For rock media, V » V
For stacked media, V * 1.6 V
For packed media, V - 1.8 V and,
For redwood slats, V - 0.7 V
4-26
-------
These adjustments reflect the relative difference in effective surface
area.
For two stage systems the basic equation is:
q.os
Where:
CVF
the fraction efficiency of the second stage
filter
C - correction factor as explained above.
The same basic equations are used for BBC systems and ABF. The
BBC surface is adjusted to compensate for effective surface area. In
the ABF system adjustments are made to compensate for the substrate (BOD)
assimilation by the activated sludge. After the efficiency of removal
for BOD is determined then this value is adjusted as a function of the
final clarifier surface area. The clarifier depth is assumed to be a
minimum of seven feet. The BOD is then calculated as a function of the
filter Influent BOD and the efficiency of removal factor. The effluent
TSS is back calculated from the effluent BOD value as a function of
observed results from several trickling filter or BBC systems. In the
ABF system, the BOD removal across the ABF biotower is calculated and
then that value is deducted from the total substrate flux to the system.
The substrate flux less the removal .through the ABF biotower is used to
determine the BOD loading to the activated sludge portion of the ABF
system. In the case of roughing filters, the same equations are used
excepting the final clarifier algorithm is not utilized.
The above equations are proprietary, however, they could be deter-
mined by back calculating these values from the basic equations presented
In this section.
4-27 -
-------
SECONDARY SYSTEM LOADING AND PERFORMANCE SHEETS
Filter. Surface Loading
This is surface loading on the filter expressed as gallons per day
per square foot based on the plant flow to the filter. It is a calculated
value for reference purposes only and is not used in the prediction model.
Filter Loading. Pounds of BOD. 1000 Ft
This is the organic loading on the filter expressed as pounds of BOD
applied per one thousand cubic feet of media. It is a calculated value
and not used in the process prediction model. It is, however, an indicator
as to potential performance.
Filter Loading for Two Stage Filters
The surface loading in gallons per day per square foot and the recirc-
ulation values are calculated and not directly used for predicted perform-
ance. The BOD loading in pounds per thousand cubic feet is a predicted
value based on the previously discussed modified NRC equations.
Clarifier Loadings, Surface GPDSF, Weir. GPP/Ft
These two values are the total clarifier surface loading in gallons
per day per square foot and the weir loading in gallons per lineal foot
per day. The weir loading is a calculated value that is an indicator only.
Representative values for weir loading are indicated in Appendix E of this
manual. The clarifier surface loading is a calculated value and used to
determine the effluent BOD concentration.
Clarifier Detention Time, Hours
This is the theoretical detention time of the final clarifiers. It is
a calculated value and used for reference purposes only. It is significant
to note that excessive detention times (greater than 4 hours) may cause
septicity to the extent where resolublization of BOD will occur along with
an increase in TSS concentration.
Effluent BOD and TSS Concentration
These are predicted values based on the modified NRC equation and
final clarifier surface loadings. The BOD is first predicted and the total
suspended solids (TSS) is estimated from the BOD values.
4-28
-------
Secondary Sludge Production
The total and volatile solids production in pounds per day is a
predicted value based on the conversion of BOD to cell mass and inert
solids flux from the primary clarifier. This determination is proprietary
in nature and, therefore, not discussed in this manual.
Total Sludge Production
These values are based on the sum of the primary and secondary sludge
productions. The percent solids is an estimated concentration of the
combined sludges based on temperature and percent of mixture of primary
and secondary sludges. The predicted values are estimates based on
idealized conditions. The actual sludge concentration may vary signifi-
cantly. Accordingly the gallons per day (GPD) of sludge pumped may also
vary since the determination is based on the predicted total pounds
produced per day and the predicted concentration. The total sludge produc-
tion data is stored in a file within the computer and used in the digester
performance section of the diagnostic model.
ROTATING BIOLOGICAL CONTACTORS (RBC)
As previously explained, the RBC algorithm is identical to the trick-
ling filter algorithms except that the computer printout presents the
organic loadings in pounds of BOD per thousand square feet of RBC surface
area. Further it prints out the loading to the first shaft or stage and
then the total load which includes the first shaft. Representative load-
ings for the first stage and total area are Indicated in Appendix E. Note
that Appendix E indicates a high loading on the first stage as 3.5 pounds
of BOD per thousand square feet. Present information indicates that load-
ings in excess of five pounds of BOD per thousand square feet on the first
stage may cause process failure and produce effluent BOD and TSS concentra-
tions In excess of the predicted values. One of the reasons for this is
that the effluent BOD and TSS predictions are based on the total surface
area. The first shaft or stage loading is calculated for reference purposes
only.
4-29
-------
DIGESTER PERFORMANCE SHEETS
All of the diagnostic programs have a digester option for perform-
ance prediction of either anaerobic digestion, aerobic digestion or both.
As previously mentioned, the data from the secondary performance sheet is
used for the digester performance output. Because of the variability in
actual sludge concentration and the fact the sludge production values are
predicted quantities based on other predicted elements, the data on this
printout may not be functional for on line plant evaluations. It is,
however, the only practical method for evaluating systems that have not yet
been built or on line systems that have no data. In order to assess on
line systems more accurately, a new program titled Digester Analysis has
been provided and will be in a subsequent Chapter. Further, the theory
and rationale for the digester predictions will be included in the sub-
sequent chapter.
Total Sludge Flow, Gallons Per Day
This value is a transferred value from the secondary performance sheet.
During the process of transfer and rounding of numbers, the flow in gallons
per day may differ by one gallon, however, this should have no impact on
the calculated or predicted values.
Volatile Solids Loading in Lbs/Ft3/Day
This is a calculated value based on the digester volume and the pounds
of volatile sludge introduced to the digester each day. It is not used
when predicting reduction of volatile solids but is an indicator of loading.
Representative loadings for the digester is indicated in Appendix E.
Mean Cell Residence Time, Days
Since the digester is assumed to be completely mixed and overflow is
equal to inflow, then the hydraulic detention time is equal to the mean cell
residence time. The value is calculated as hydraulic residence time and
expressed on the printout as mean cell residence time. This value is used
to predict the percent reduction of volatile solids.
4-30
-------
Percent Reduction of Volatile Solids
This is a predicted value based on the mean cell residence time.
The algorithm will be discussed In a subsequent chapter for the digester
analysis program. The diagnostic program limits the maximum percent
reduction of volatile matter to 75Z.
Alkalinity, mg/1
This is a predicted value based on the concentration of raw sludge
fed to the digester. It is a derivation of a simple yet accurate formula
first published in 1968 in the WPCF Manual of Practice No. 16, page 17.
This value is not calculated for aerobic digestion.
Gas Production, Ft Per Day
The total gas production per day in cubic feet is for anaerobic
digestion only. It is calculated from the predicted percent reduction of
volatile matter. It is assumed that the gas quality is approximately
352 carbon dioxide and 65Z methane which equates to about 15 cubic feet
per Ib of gas under standard conditions.
Percent Solids of Digested Sludge
This is a calculated value based on the percent reduction of volatile
solids, the percent solids of the raw sludge, and the daily raw sludge
flow. It assumes that the digester is completely mixed. The equation is
presented in the subsequent chapter.
4-31
-------
CHAPTER 5
DIGESTER AND ACTIVATED SLUDGE
ANALYTICAL AND TROUBLESHOOTING PROGRAMS
INTRODUCTION
These programs are new to the diagnostic series. They are intended
to augment the general diagnostic program by providing additional infor-
mation to troubleshoot problems in the field. The digester program
includes both aerobic and anaerobic digestion. The activated sludge
system analytical program is applicable for all types of activated sludge.
RUNNING THE DIGESTER PROGRAM
To run the program type: HELLO , the computer reads the
first message and displays it on the screen. Make sure the "Cap Locks"
key is on. The first message gives the user three options,- the digester
analysis, activated sludge, or an activated sludge example. If Digester
Analysis is selected the computer will then ask what type, Anaerobic or
Aerobic? The user must select one option. For explanatory reasons,
anaerobic digestion will be used because it includes all the possible
parameters. Whereas in aerobic digestion alkalinity and gas production
is not considered, therefore, an N/A (not applicable) is printed for
these parameters.
The next question asks if the raw sludge contains waste activated
sludge. The user must respond Y (yes) or N (no). If the user answers
yes then the computer asks for the mean cell residence time (MCRT) days.
Even if the sludges are pumped separately to trie digester the mean cell
residence time should be inputted.
5-1
-------
The computer will continue to ask questions and if there are no
changes desired (edit routine) then the program will print out the
calculated values and predicted values. All of the questions are simple
and should be available for input, however, there will be times when the
information is not available. You must enter some number. Do not enter
zero (0) because it may cause a division by zero and subsequently the
computer will stop and display this message. It is suggested that if you
do not know the actual required input values either guess them or enter
the value one CD which will render unrealistic results but still allow
the program to run. The following parameters must be inputted into the
computer:
1. Mean Cell Residence Time, Days (if an activated sludge system)
This value should be entered to the nearest integer. It is
necessary to know the value or be close to it.
2. Digester Volume. Gallons x 1000
Enter this value to the nearest thousand gallons. As an
example, if the digester, volume were 835,421 gallons the
operator should enter 835*000.
3. Raw Sludge Flow. Gallons Per Day
This value should be entered to the nearest integer.
It is necessary to know this value or be close to it to
produce meaningful results.
4. Saw Sludge Solids, Percent
This value should be entered to the nearest tenth. It
is necessary to know this value or be close to it to
produce meaningful results.
5. Raw Sludge Volatiles, Percent
This value should be entered to the nearest integer. The
value should be known or close to it in order to produce
meaningful results.
6. Digester Temperature. Degrees Celsius
This value should be entered to the nearest integer. The
values should be known or accurately estimated to produce
meaningful results.
5-2
-------
7. Digester Liquor Solids. Percent
This value, if known should be entered to the nearest tenth.
If it is not known, either estimate it or enter one. It
will affect the calculated values only.
8. Digester Volatile Solids, Percent
This value should be entered to the nearest integer. If it
is not known either estimate the value or enter one. It
will affect the calculated values.
9. Gas Production, X 1000 ft3
This value should be entered to the nearest 1000 cubic feet.
If it is not known then either estimate the value or enter
one. This Input will affect the calculated values only.
10. Alkalinity, mg/1. as Calcium Carbonate
Enter this value to the nearest integer. If the actual value
is not known then you may estimate it or enter the value one.
It is used in the calculated values only.
11. Volatile Acids, mg/1, as Acetic Acid
Enter this value to the nearest integer. If the actual value
is not known then either estimate the value or enter one.
This value only affects the calculated values.
CALCULATED VALUES
Detention Time, Days
This value is printed to the nearest day or integer. It is calculated
as follows:
9 - v
Fs
Where:
9 - the hydraulic retention time in days
V - the digester volume in gallons
F_ » the raw sludge flow in gallons per day
3
5-3
-------
Organic Loading. Pounds of Volatile Solids
Per Cubic Foot Per Day
This value is printed to the nearest one hundreth of a pound and
is calculated as follows:
L . 0.00834 F_ R. R
0 0.133?V
Where:
LO - Organic loading in pounds of volatile solids
per cubic foot of digester volume per day.
F - Raw sludge flow in gpd
U
c • Raw sludge concentration in percent
' R - Raw sludge volatile content in percent
V « Volume of the digester in gallons.
Reduction of Volatile Solids in Percent
This value is printed to the nearest integer and is calculated as
follows:
X 100
o.oi RV - ro.oooi Rvor
1
J
Where:
V - Volatile solids reduction in percent
R * The raw sludge percent volatile solids
D • The digested sludge percent volatile solids
Reduction of Volatile Solids in Pounds per Day
The value is indicated to the nearest integer and is determined as
follows:
V - 0.0000834
Where: V - Ibs of volatile solids reduced per day.
P
Note: Other variables have been previously identified.
5-4
-------
Gas Yield In Cubic Feet of Gas Produced per Pound
of Volatile Matter Destroyed
This value is calculated and printed to the nearest tenth of a
cubic foot of gas and is determined as follows:
F
Where:
Y
8 V
P
Y - Gas yield in cubic feet of gas per Ib of volatile
* matter destroyed.
F - Gas flow in cubic feet per day
V - The pounds of volatile solids destroyed per day.
Alkalinity/Volatile Acid Ratio
This is a non-dimensional number and is merely the ratio between the
alkalinity and the volatile acids. It is used by some operators and engi-
neers as an indicator as to the condition of the digester.
Actually it is not the condition of the digester but rather the
buffering capacity. If Alk/VA ratio was 2.5 this would mean that the
buffering capacity is approximately 2.5 times the volatile acid concentra-
tion. It is strictly a simple stochiometric relationship as follows:
When alkalinity is determined as calcium carbonate (CaCO ), it indi-
cates the buffering capacity in the digester against volatile acids.
Assuming the buffer is calcium carbonate and the volatile acid is acetic,
the reaction is:
2CH3COOH + CaC03 "• Ca(CH3C002> + ^Q^
The reaction product is an organic salt, calcium acetate and carbonic
acid. The carbonic acid (H.CO.) further breaks down into carbon dioxide
(CO ) and water (H_0) . It is now obvious that if a large increase in
volatile acids occurred there also would be an increase in carbon dioxide
in the digester gas. The carbon dioxide increase will be indicated in the
gas analysis. It is also significant to note that the pH will remain the
same until most of the alkalinity is used up by increased volatile acid
production. The higher the alkalinity, the better the buffering capacity
5-5
-------
and the less chance for digester upset caused by sharp volatile acid
increases. Also, if the alkalinity concentration is known, then the
operator can predict when the pH will drop, and add chemicals such as
lime or ammonia to maintain the proper pH for the methane formers. Since
it takes one mole of CaCO- to neutralize two moles of CH.COOH and the
molecular weight of the calcium carbonate is 100 and acetic acid is 48,
the reaction is in direct proportion. As an example, if the volatile
acid concentration increased by 1,000 rag/1 as CH.COOH, the required
alkalinity would be computed as follows:
mg/1 CaCO^ required • volatile acid increase in mg/1
mole wt. of CaCO. 2 mole wts of CH.COOH
substituting,
x
100
(1000)(100) - 1,020 mg/1 CaCO. required
* " 98 J
As a rule of thumb, one milligram of calcium carbonate neutralizes
one milligram of acetic acid. This assumes a strict stoichiometric
reaction with the above mentioned compounds. There are many other vola-
tile acids that have higher and lower molecular weights such as valeric
acid (CH-CCH^COOH), butyric (CH3CH2COOH) and formic acid (HCOOH). Also,
in the carbonate group, magnesium, potassium, and sodium carbonate exist.
Being cognizant of this, it is good policy to keep at least 1,000 mg/1 of
alkalinity ahead of any volatile acid concentration.
As for determining gas production, this is important with respect
to determining process efficiency and materials balance as is volatile
solids determinations. Considering the laws of mass conservation and
energy and a digester gas containing 35 percent carbon dioxide and 65
percent methane only 13.9 cubic feet of gas can be produced per pound
of volatile matter destroyed. This can be easily proved by applying
Avagadro's law which deduces that one gram mole of any gas will produce
a volume of 22.4 liters under standard conditions. It is determined as
follows:
Compute molecular weights of CO. + CH,
5-6
-------
C - 12 x 1 - 12 C - 12 X' 1 - 12
0-16x2-32 H - 1 x 4 - _4
44 grams 16 grams
AC 0.35 C02 and 0.65 CH, compute weight of 22.4 liters of gas at
standard temperature and pressure.
0.35 x 44 - 15.4
0.65 x 16 - 10.4
25.8 grams per 22.4 liters
3
1 ft - 28.3 liters, 1 pound * 454 grams
Compute volume of gas weighing one pound
25.8 „ 454 . (454)(22.40)
2274 T ' X " 2O " 396 liters
or " 396 - 13.9 cubic feet of gas from one pound
28.3
Checking digester loadings and retention times aids in determining
process problems with respect to proper operation within the design
parameters. Mass balance calculations assure proper analysis and flow
measurement for good process control. Every operator knows it is necessary
to balance his check book in order to prevent trouble. The same principle
applies to operating a digester or, for that matter, any unit process.
5-7
-------
PREDICTED VALUES
The predicted values are based at least in part on theoretical equa-
tions and input values such as raw sludge flow, digester volume and
temperatures. These values can be compared to the calculated values and
if they differ significantly there is something definitely wrong. The
predicted values assume a well mixed digester. They are more accurate
than the diagnostic models not only because of the input accuracy but
also they better correct for temperature and waste activated sludge
loads. The predicted values are as follows:
Reduction of Volatile Solids. Percent
This value is expressed to the nearest integer and is determined
by the following equation:
100
Vr " L " 1 + 0.05 9 (I.OIS8"^) (LOSS'S)
Where:
V * the reduction of volatile matter in percent
9 » the digester hydraulic residence time in days
which is also equal to the mean cell residence time
for a completely mixed reactor.
5-8
-------
QC » the mean cell residence time of the activated sludge
system if any.
t • Temperature of the reactor in degrees Celsius.
ts - 20*C for aerobic digestion and 37°C for anaerobic
digestion.
If Vr is computed to be greater than 80Z then V is set at 80Z.
Seduction of Volatile Solids, Pounds per Day
This value is expressed to nearest integer and is calculated as follows:
V - 0.0000834 F R R V
p s c v r
Where:
V Ibs of volatile solids destroyed per day
Note: The other variables have been previously identified. The
7V is the theoretical and not the calculated value.
Digester Liquor Solids, Percent
This -value is expressed to the nearest tenth, and is calculated as
follows:
st- si + (vi " V x 100
8.34 Fr
Where:
S - Total digester liquor solids expressed in percent.
S - Ibs. of inert solids introduced to the digester each day.
7 - Ibs. of volatile solids introduced to the digester each day.
V » Ibs. of volatile solids reduced each day.
P
F • Raw sewage flow in gallons per day.
Digester Volatile Solids in Percent
This value is expressed to the nearest integer and is calculated as
follows:
5-9
-------
V - V
v » * P y 100
3 Si + (Vi * VP)
Where:
V » the percent volatile solids in the digester liquor
s
Gas Production in Cubic Feet x 1,000
This value is expressed as cubic feet x 1,000 and is calculated as
follows:
* 1,000
Where:
6 • the gas production in cubic feet per day x 1000
V « Ibs. of volatile matter theoretically destroyed per day
Note: 14.5 is assumed to be the nmy-t™™ gas produced per Ib
of cubic feet destroyed per day.
Alkalinity as CaCOj in mg/1
Lt - RC [1000 - (20 oc)J
Where:
A » the alkalinity in the digester expressed as mg/1 of CaCO.
R - the raw sludge concentration in percent
9 - the mean cell residence time of the activated sludge in
days.
Comparison of Theoretical Data with Calculated Data
Even when the most precise data is available, the theoretical and
calculated data will not match exactly, but they should be reasonably close.
When the calculated data shows a substantially better reduction of
volatile solids than the theoretical, this may be due to incorrect analytical
data. A typical example of this is the raw sludge flow and concentration.
Often the raw sludge concentration is higher than actual or the flow is
higher than actual. If the pounds of volatile solids introduced to the
5-10
-------
digester is actually less than reported then the gas yield or production
will be lover than the theoretical. It is suggested that a mass balance
be performed around each unit process to verify the data. In order to
demonstrate the value of this, consider the following example:
Raw sludge is pumped into a well-operated, heated and mixed digester.
The digester liquid is transferred to a holding tank by displacement of a
uniformly fed raw sludge and subsequently dewatered by a vacuum filter.
Design Parameters
1. Digester capacity - 2 million gallons.
2. Digester loading should be less than 0.2 pounds of volatile
matter per ft3 per day (3 kg per m3).
3. Digester detention time should be greater than 20 days.
Operating and Analytical Data
1. Raw Sludge
a. 73,200 gallons per day
b. Average concentration - 5.2 percent total matter
c. Volatile content -79.6 percent
d. Gas production - 225,000 ft /day at 35 percent
CO. and 65 percent CH,-
e. Digested sludge -2.5 percent total matter
f. Digested volatile content » 57.7 percent
Check Digester Loading
(73,200 gal)(0.052)(0.796)(8.34) - Ibs of volatile matter
- 25,300 Ibs of volatile matter
Digester volume - 2,000,000 gallons or 2,000.000 - 267,380 ft
7.48
Therefore the loading in pounds of volatile matter per cubic
foot per day is:
25.300 - 0.095 Ibs of VM/ft3/day
267,380
Note: Loading is less than half of design parameter.
5-11
-------
Check Digester Detention Time
73,200 gallons per day input
Digester volume - 2,000,000 gallons
Therefore:
- 27.3 days detention time
Note: Detention time falls within design parameters.
Check Materials Balance
1. Compute solids into reactor
Known: 73,200 gallons input per day at 5.2 percent
matter and 79.6 percent volatile
Therefore:
(73,200)(0.052)(8.34) - 31,800 Ibs solids/day
(31,800)(0.796) - 25,300 Ibs volatile solids/day
2. Compute percent reduction of volatile matter
Known: 79.6 percent volatile in
57.7 percent volatile out
Since percent reduction of volatile matter is relative,
assume 100 Ibs dry weight is to be digested.
Therefore:
100 Ibs of sludge would contain 79.6 Ibs of volatile
matter (79.6 percent) and 20.4 Ibs of fixed or non-
volatile solids (20.4 percent).
5-12
-------
The fixed or non-volatile solids will remain the same after
digestion since they are non-biodegradable. Therefore, the
remaining sludge will contain 20.4 Ibs of fixed material.
The remaining sludge is 57.7 percent volatile and 42.3 per-
cent fixed.
Therefore:
42.3 percent of total remaining sludge equals 20.4 Ibs.
Changing the statement to an algebraic expression:
0.423 T - 20.4
Where:
20 4
T - Q - 48.2 Ibs total after digestion
Then, 48.2 Ibs total after digestion
Less 20.4 Ibs of fixed solids
27.8 Ibs Volatile solids after digestion
79.6 Ibs volatile matter before digestion
Lass 27.8 Ibs volatile matter remaining
51.8 Ibs volatile matter removed during digestion
x 100
Therefore:
Ibs volatile matter removed
Ibs volatile matter before digestion
» percent reduction of volatile matter
51 8
°r» m' c. x 100 » 65 percent reduction of volatile matter
/ 7. b
3. Compute solids discharged from digester
Known: 31,800 Ibs total to digester
-25.300 Ibs volatile solids to digester
6,500 Ibs fixed solids to digester
5-13
-------
65 percent of the volatile matter is reduced or converted to gas
or, (0.65)(25,300) - 16,450 Ibs of volatile matter
converted to gas
25,300 Ibs volatile solids to digester
-16,450 Ibs volatile solids converted to gas
8,850 Ibs volatile solids discharged from digester
4. Draw a simple digester diagram and indicate all
computed input and output data. See Figure 1.
5. Check mass balance based on computation and analysis.
a. Solids Input. As indicated on Figure 1 and computed
by analysis and flow measurement.
b. Solids Ouput.
1) Computed by percent reduction of volatile matter
and assuming input gallons equals output gallons.
See Figure 1 and previous calculations.
2) Compute by analytical and operating data
73,200 gallons out
2.5 percent matter
Therefore:
(0.025)(73,200)(8.34) - 15,260 Ibs out
Compute volatile matter out:
(0.577)(15,260) - 8,800 Ibs volatile
15,260 - 8,800 - 6,460 Ibs fixed
c. Compare by computed and analyzed output in pounds.
Computed Analyzed A
Total Solids 15,350 15,260 +90
Volatile Solids 8,850 8,800 +50
Fixed Solids 6,500 6,460 +40
Note: Accuracy is approximately 0.6 percent,
15 percent accuracy is considered good.
5-14
-------
GAS OUTPUT
16,450 IBS OF GAS
COMPUTED
BY
SOL IOS
LOSS
SOLIDS INPUT
73.200 GALLONS
in
I
25,700 LBS VOLATILE SOLIDS
6,500 LBS FIXED SOLIDS
31.800 LBS TOTAL SOLIDS
DIGESTER
651
CONVERSION
OF VOLATILE
SOLIDS TO
GAS
SOLIDS OUTPUT
73.200 GALLONS
8,850 LBS VOLATILE SOLIDS
6.500 LOS FIXED SOLIDS
15,350 LBS TOTAL SOLIDS
-------
d. Compare actual or measured gas production with
calculated production.
1) Measured gas production is 225,000 ft per day.
2) Based on 65 percent CH, and 35 percent CO. and
100 percent conversion of volatile solids to gas.
See previous calculation where one pound is
converted to 13.9 cubic feet. Therefore, the
theoretical gas production should be:
(16,450 Ibs destroyed)(13.9) - 228,600 ft3 gas
Mote: Accuracy is within limits.
6. Conclusion
Mass balance checks out, therefore analytical data and flow
measurement are correct. The computer program is based on a
mass balance except the weight of gas is not calculated, but
is assumed .to be 14 to 15 cubic feet of gas per Ib of volatile
matter destroyed.
ACTIVATED SLUDGE ANALYSIS
The activated sludge analysis program is intended to analyze and
troubleshoot all conventional activated sludge systems including extended
aeration and oxidation ditch systems. The program does not address contact
stabilization or activated biofilter (ABF) systems. Even though the
program appears to be simple with regard to data input and output, it is
actually complex with many variables and combinations that is beyond the
scope of this manual. For this reason there has been included an example
program to familiarize the user with some of these variables.
Inputting Data
Note: The program is structured for ease of editing input data
because it is recognized that in many plants all the required data is not
available and therefore must be estimated. The values or parameters that
are estimated may require revision several times or until the plant is in
reasonable balance.
5-16
-------
When the activated sludge analysis program is selected (.not the
example program) it first asks for your name. Input your name using less
than 20 characters. It then asks for the date and gives an example on how
to input the date. If the date is inputted incorrectly the computer will
tell you to use the correct format. As an example, if the value of 13
is inputted as the month it will tell you that the month number is out of
range and asks you to input the date again.
After'proper input of the date the computer then asks for the plant
name. The computer will accept up to 20 characters.
The program then asks if you wish to change any of the information.
If you enter yes then you must input all of the data. If no (N) is
pushed then the programs proceeds to the next step. You are then asked
to input the treatment plant data as follows:
1. Total Reactor Volume in gallons.
2. Total Final Clarifier surface area in square feet.
3. Average clarifier sidewater depth in feet.
' The above information must be accurate. If this data is not known,
it can be measured in the field. After inputting the data the computer
will then display the information inputted with an Edit (£) or Quit (Q)
option. If E is pressed then it will allow you to edit any one of the
entries. It will ask you for the line number. Enter the line number and
hit return, and after the value is inputted it will again give the edit
or quit routine. If Q is pressed then it will go to the next section for
entry of wastewater characteristics.
There are IS parameters in the wastewater characterization section.
Again some of these parameters may not be known but can be estimated and
some of them may be redundant, such as the return activated sludge and
waste activated sludge concentrations which are usually the same. The
following is a list of parameters with a brief discussion:
1. Influent flow in gpm. If this data is not available then
the flow must be estimated. If possible measure the flow
using basic hydraulic formulas at an existing flume or channel.
5-17
-------
2. Daily peak, influent flow in gpm. This means the daily peak
flow for the normal 4 to 6 hour duration. Again, it can be
measured. For most facilities, the peak flow is about 1.5
times the average daily flow.
3. Influent BOD in mg/1. If this average value is not available
it can be estimated and adjusted later to balance the system.
An experienced individual can make a good guess as to strength.
If this is not possible a good starting point would be 200 mg/1.
4. Influent total suspended solids in mg/1. If this value is not
known, several grab samples should be analyzed. The average
of these values should be utilized. A GUESS IS NOT ADEQUATE
FOE A STARTING POINT.
5. Influent volatile suspended solids in percent of total. If the
value is not known, several grab samples should be analyzed and
the average value utilized. A GUESS IS NOT ADEQUATE FOR A
STARTING POINT.
6. Mixed liquor suspended solids in mg/1. If this value is not
known, several grab samples should be analyzed and the average
value utilized. A GUESS IS NOT ADEQUATE FOR A STARTING POINT.
7. Mixed liquor volatile suspended solids in mg/1. If this value
is not known, several grab samples should be analyzed and the
average value utilized. A GUESS IS NOT ADEQUATE FOR A STARTING
POINT.
8. Reactor dissolved oxygen concentration in mg/1. If records are
not available, the dissolved oxygen concentration should be
measured. Obviously it is a significant parameter since lack
of adequate oxygen will cause system failure.
9. Return activated sludge concentration in mg/1. If this value
is not known, several grab samples should be analyzed and the
average value utilized. A GUESS IS NOT ADEQUATE FOR A STARTING
POINT.
5-18
-------
10. Return activated sludge flow in gpd. If this value can not
be measured or estimated then the user should guess the value.
It can be determined later provided the RAS concentration is
known.
11. Waste activated sludge concentration in mg/1. If this value
is not known, several grab samples should be analyzed and the
average value utilized. A GUESS IS NOT ADEQUATE FOR A
STARTING POINT. If wasting is performed via the return acti-
vated sludge line then these values should be the same.
12. Waste activated sludge flow in gpd. If this value is not
known and can not be measured or estimated then the user
should guess the value. It can be determined later provided
the WAS concentration is known.
13. Average clarifier blanket depth in feet. This is the sludge
blanket depth measured from the clarifier surface down to the
blanket. THIS VALUE MOST BE KNOWN and if information is not
available, the user should measure the blanket depth with a
blanket finder or similar device.
14. Sludge volume index in grams/ml. If this value is not known,
several grab samples should be analyzed and the average value
utilized. A GUESS IS NOT ADEQUATE FOR A STARTING POINT.
15. Zone settling velocity in feet per hour. THIS TEST MUST BE
DONE. It is recognized that it is not normally done in waste-
water treatment plants, therefore Appendix H includes a dis-
cussion on zone settling velocity (ZSV), methodology and
associated forms.
16. Effluent total suspended solids in mg/1. It is assumed that
this value is known since it, along with effluent BOD is the
basis for determining the need to analyze the treatment plant.
17. Effluent BOD in mg/1. It is assumed that this value is known
since it, along with effluent TSS is the basis for determining
the need to analyze the treatment plant.
5-19
-------
18. Water temperature in degrees Celsius. This should be the
temperature of the mixed liquor in degrees Celsius. If it
is not known through recorded data it should be measured.
After the above data is entered, all the data is displayed by line
item. With an Edit (E) or Quit (.Q) option. If E is pressed the computer
will ask for the line number. Enter the line number and press return.
It will then display the parameter selected. Enter the new parameter and
press return. It will again display all the entered values with the
Edit or Quit option. All of the parameters may be changed as many times
as required.
When Quit (Q) is pressed the program proceeds to the next step.
This step examines the solids balance around the final clarifier. It
computes the «•»•»««< liquor flow in pounds and the clarifier underflow in
pounds. If the balance is not within reasonable limits, the computer will
indicate that it is not, and gives you the option to change the RAS flow
or concentration. If the user enters yes. (Y) then the return sludge flow
is requested. Then you also have the option to change the RAS concentra-
tion. If the user decides not to make any changes and presses N when the
computer first asks, then the computer will automatically change the RAS
concentration to balance the system. There are several other options and
routines that will be explained in the example program discussion.
After the solids balance is within reasonable limits the computer then
determines the mean cell residence time (MCRT) in three different ways using
the data as it stands at this point. If the MCRT values are not reasonably
consistent, then the computer will so indicate and give the option to go
back and input new values. After new values are inputted then it will again
look at the solids balance around the final clarifiers and if within acceptable
limits then proceed to the MCRT balance. If the MCRT values are within
reasonable limits the user must set the MCRT. The user may enter a new MCRT
based on his best judgment or one of the calculated MCRT values.
After the MCRT is set then the user may enter Quit (Q) where the user
will be given the option to print the data and diagnostics on the screen or
the printer.
5-20
-------
The computer, after the screen or printer printout, then asks if
you wish another run. If you desire to run the program again and keep
the existing or previously inputted values, then press yes (Y), if not
press no (N).
PROGRAM THEORY
After the user inputs the data a solids balance is performed around
the final clarifier. Effluent TSS is neglected because normally it is
not sensitive to the analysis. The balance is based on reasonable limits
and not precise pounds. The solids flow (flux) to the clarifier is
computed as follows:
Pt - 8.34
Where:
P. » Ibs per day to the final clarifier
X. - the mixed liquor suspended solids
concentration in mg/1
F - average daily plant flow in mgd
. F • the daily return activated sludge in mgd
The underflow flux is computed as follows:
- 8.34 (Xr)(Fr)
Where
P - Ibs per day of solids removed from the final clarifier .
o
X - the inputted RAS suspended solids concentration in mg/1
F » the RAS flow in mgd.
After the above is balanced as previously discussed then the computer
determines the MCRT three ways. These are:
1. By wasting method
2. By inert solids method
3. By the kinetic method.
All of the above methods use the reactor volume only in the computation.
5-21
-------
The wasting method is calculated as follows:
9cw - r *
Where:
9
cw - Mean Cell residence time based on wasting
7 • Reactor volume in millions of gallons
X. * Mixed liquor solids concentration in mg/1
F - Waste flow in mgd
w *
X » Concentration of TSS in waste flow expressed in mg/1
The inert method is calculated as follows:
V X,
9ci -
Where:
9 . « the mean cell residence time based on inert solids
7 - Reactor Volume In millions of gallons
X. • The concentration of inert solids (non volatile)
in the mixed liquor expressed as mg/1
F - Average daily plant flow in mgd
I - The concentration of inert solids (non volatile)
In the reactor influent expressed as mg/1.
The kinetic method is computed as follows:
Yq -
Where :
9 * Mean cell residence time
c
Y - 0.6 Ibs of cell mass produce per Ib of BOD
catabolized per day
q - Substrate removal velocity in Ibs of BOD removed
per Ib of cell mass per day
=• Endogenous respiration rate to the minus one days.
Kd
5-22
-------
After Chese values are calculated and the MCRT is set then the
computer performs an analysis on the system and prints out all of the
data and performs a diagnostic of the inputted and calculated data.
Statements are printed out as to the possible cause of poor performance.
These statements are manifold and not discussed in this text.
As previously stated there are so many variables and conditions
involved, it would be impossible to cover all the conditions. It is
recommended that the user spend a few hours running the Example program
in order to become familiar with the program and its flexibility.
RUNNING THE EXAMPLE PROGRAM
Select the example program on the main menu by entering the appro-
priate number. It will boot or start automatically.
Next the screen will display the date, a persons name, and the plant
name. When using the regular program the computer will ask these questions.
In the example all the data is Inputted for you. Press N for NO to indicate
that you do not wish a change and to continue on in the program.
The computer then displays the unit process data. Press Q to con-
tinue.
The computer then displays the wastewater characteristics data.
Note the data, then press Q to continue.
The computer also displays MCRT values calculated three ways. Note
that these values are nearly perfectly matched.
Now press G to go back. The computer will now display the wastewater
characteristics previously displayed. Press E for Edit. The computer will
then ask for the line number. Enter 9 and press return. Line item No. 9
is the RAS concentration in mg/1. Enter 5,000 for the RAS concentration
5-23
-------
APPENDIX A
ALGORITHM SOURCES
-------
APPENDIX A
ALGORITHM SOURCES
The algorithms used in the Diagnostic Operational Modeling Programs
were prepared solely by:
Mr. Dave Sullivan
ES Environmental Services
600 Bancroft Way
Berkeley, California 94710
Assistance with development of the program formats and preparation
of this manual was provided solely by:
Timothy L. Sullivan
Roy M. Monier
Drew D. Mclntyre
Clarisse A. Severy
ES- recognizes the substantial contribution and guidance given by
the EPA Project Officer, Mr. Tom Johnson, EPA Region X.
ES- recognizes the following individuals that participated in the
peer review and offered helpful suggestions.
Mr. David Thornburg
Coachella Valley Water District
Mr. Charles E. Corley, R.S.
Illinois Environmental Protection Agency
Ms. Veronica Fitz
Boise State University, Idaho
Mr. James Kohl
State of Wisconsin Dept. of Natura^. Resources
Mr. Bill Mixer
Casper College, Wyoming
Mr. D. Wayne Staples
State Water Control Board
Common Wealth of Virginia
A-2
-------
APPENDIX B
INFLUENT AND EFFLUENT WASTEWATER
DATA SHEETS
-------
APPENDIX B
INFLUENT AND EFFLUENT WASTEWATER
DATA SHEETS
Treatment Plant Name:
Location (In what state):
Wastewater Characteristics Input Data:
Average dry weather flow _ (MGD)
Average wet _weather flow _ (MGD)
Peak dry weather flow _ (MGD)
Peak wet weather flow _ (MGD)
Design dry weather flow _ (MGD)
Design peak wet weather flow _ (MGD)
Influent BOD Qng/1)
Influent TSS (total suspended solid) (mg/1)
Influent VSS1'2 (volatile suspended solids)
Temperature (niaTfiTmim/nHtfinnmi / (*C)
_ 2
TKN (total Kjeldahl nitrogen) _ (mg/1)
Alkalinity2 _ (mg/1)
PH2 _
7
PO.-P (Orthophosphates) _ (mg/1)
MaT-trm^ MLSS _ (mg/1)
Maximum MCRT _ (days)
Footnotes: 1. Be sure that this value is expressed as a percentage
of total suspended solids, rather than a concentration
in mg/1.
2. If you are not sure about these values, just leave them
blank; default values will be assigned by the computer
programs.
3. For activated slugge only.
B-2
-------
Effluent Characteristics (existing)
Av». vet weather flow Avg. dry weather flow
BOD
TSS
VSS
pH
TKN
NO.
Plane Superintendent
til
Phone No. ( )
-------
APPENDIX C
TREATMENT PLANT CONFIGURATION
DATA SHEETS
-------
APPENDIX C
TREATMENT PLANT CONFIGURATION
DATA SHEETS
Treatment Plant Name
State of
Type of Treatment Plant (check appropriate box)
( ) 1. Primary treatment
( ) 2. Conventional activated sludge, with or without
primary sediemntation
( ) 3. Single stage activated sludge for nitrification,
with or without primary sedimentation
( ) 4. Extended aeration with or without primary sedimentation
( ) 5. Extended aeration oxidation ditch with or without
primary sedimentation
( ) 6. Contact stabilization, with or without primary
sedimentation
C ) 7. Single stage trickling filter with primary sedimentation
( ) 8. Two stage trickling filter with primary sedimentation
( ) 9. Activated Bio-Filter Process, with or without primary
sedimentation
( ) 10. Rotating biological contactors with or without primary
sed Imentat ion
( ) 11. Roughing Filter followed by activated sludge
( ) 12. Digester Analysis
1. Primary Clarification Input Data:
Circular Clarifiers
Clarifier Number #1 #2 #3 #4 #5.
Diameter of ea. clarifier (ft)
Avg. depth of ea. clarifier (ft)
Weir length of ea. clarifier (ft)
Rectangular Clarifiers
Clarifier Number #1 #2 #3 #4 #5.
Length of ea. clarifier (.ft)
Width of ea. clarifier (ft)
Avg. depth of ea. clarifier (ft)
Weir length of ea. clarifier (ft)
-------
Fine Screen
Are fine screens being used (yes or no) :
If yes, answer the following questions:
Type of screen:
Number of screens:
Width (ft):
Height (ft):
Screening opening: (in):
Capacity ea. (MGD):
2. Secondary Clarification Input Data:
Circular Clarifiers
Clarif ier Number #1 92 93 #4 «
Diameter of each clarifier (ft)
Avg. depth of ea. clarifier (ft)
Weir length of ea. clarifier (ft)
Rectangular Clarifiers
Clarif ier Number 91 92 //3 #4 #5
Length of ea. clarifier (ft)
Width of ea. clarifier (ft)
Avg. depth of ea. clarifier (ft)
Weir length of ea. clarifier (ft)
3. Reactor(s) Input Data:
Type of Reactor: Circle the type of process shown below and indicate
the dimensions for each of the reactors
Activated Sludge/Extended Aeration
Circular Reactors (Aeration Basins)
Reactor Number #1 #2 £3 M #5
Diameter (.ft)
Water depth (ft)
C-3
-------
Rectangular Reactors (Aeration Basins)
Reactor Number 11 92 13
Length of ea. basin (ft)
Width of ea. basin (ft)
Avg. depth of ea. basin (ft)
Extended Aeration Oxidation Ditch
Pitch Number II 12 13 I4_
Volume of ea. ditch (gal)
Contact Stabilization
Round Reaeration Tanks
Tank Number II 12 13
Volume of ea. tank (MC)
Rectangular Reaeration Tanks
Tank Number II 12 13
Length of ea. tank (ft)
Width of ea. tank (ft)
Avg. depth of ea. tank (ft)
Round Contact Tanks
Tank Number
Volume of ea. tank (MG)
Rectangular Contact Tanks
Tank Number II £2 I3_
Length of ea. tank (ft)
Width of ea. tank (ft)
Avg. depth of ea. tank (ft)
C-4
-------
Activated Bio-Filter (ABF)
Bio-tower media (.circle one): Redwood, stacked plastic, packed plastic
Arc bio*towers constant flow or constant recirculation:
Circular Bio-Filters II 12 13 14
Diameter of ea. bio-filter (ft)
Depth of ea. bio-filter (ft)
Flow rate (GPM)
Rectangular Bio-Filters II 12 13 14 I5_
Length of ea. bio-filter (ft)
Width of ea. bio-filter (ft)
Depth of ea. bio-filter (ft)
Flow rate (GPM)
Circular Aeration Basins
Reactor Number II £2 13 14 IS
Diameter (ft)
Avg. depth (ft)
Rectangular Aeration Basins
Reactor Number II 12 13 9k 95
Length of ea. basin (ft)
Width of ea. basin (ft)
Avg. depth of ea. basin (ft)
Activated Sludge/Extended Aeration/Contact Stabili»ation/ABF
Type of aeration (circle one): diffused air. mechanical aeration
Tank Number II £2 13 14 15.
diffused: scfm/reactor
•echanical: hp/reactor
-------
Single Stage Trickling Filter
Filter media (circle one): rock, stacked plastic, packed plastic
Are filters constant flow, constant recirculation, or percent recirculation
Filter number #1 #2 #3 M #5
Diameter of ea. filter (ft)
Depth of ea. filter (ft)
Flow rate (GPM)
Two Stage Trickling Filter
Primary Filter media (circle one): rock, stacked plastic, packed plastic
Are filters constant flow, constant recirculation, or percent recirculation
Primary Filter Number #1 #2 #3 #4 #5_
Diameter of ea. filter (ft)
Depth of ea. filter (ft)
Flow rate (GPM)
Secondary Filter Media (circle one): rock, stacked plastic, packed plastic
Are filters constant flow, constant recirculation, or percent recirculation
Secondary Filter Number #1 £2 #3 #4 #5_
Diameter of ea. filter (ft)
Depth of ea. filter (ft)
Flow rate (GPM)
C-6
-------
Rotating Biological Contactor (RBC)
Manufacturer of RBC units
Type of drive unit (air or mechanical)
No. of process trains
No. of stages per train
Stage No. 1 surface area/per stage
Stage No. 2 " t. « „
Stage No. 3 M " H
Stage No. 4 " " " ."
Stage No. 4 "
Stage No. 5
Stage No. 6
n it
ft
ft
ft
ft'
ft'
ft'
ft'
Example:
I inflow
No.
No.
1 No.
No.
No.
No.
1
2
3
4
5
6
No.
No.
No.
No.
No.
No.
1
2
3
4
5
6
I »
to secondary clarifier
In example there are two trains
with six stages in series. Stage
Nos. 1,2,3 in each train have
100,000 ft2 of surface area each
or a total of 600,000 square feet.
Stages Nos. 4,5,6 have a surface
area of 150,000 ft? each or a
total of 900,000 ft2.
C-7
-------
Sludge Digestion Input Data:
Anaerobic Digestion
Primary Digesters
Tank Number *1 #2 #3 #4
Volume of each primary digester ______________«-—__ gallons
Are the digesters heated (yes or no)
Are the digesters mixed (yes or no)
Is there any type of thickening prior to digestion? If so what kind
Secondary Digesters
Tank Number #1 #2 #3 #4
Volume of each digester gallons
Can the digesters be heated (yes or no)
Can the digesters be mixed (yes or no)
Aerobic Digestion
Tank Number #1 92 ' #3 #4
Volume of each digester -_^___-______^_—_-___-___—____ gallons
Is there any type thickening prior to digestion? If so what type
Additional Data for Digester Diagnostic
MCXT if Applicable Days
Raw Sludge flow GPD
Raw Sludge Solids %
Raw Sludge Volatiles 7.
Digester Temperature °C
Digester Liquor Solids Z
Digester Volatile Solids 7.
Gas Production X1000 ft3*
Alkalinity as CaC03 MG/L*
Volatile Acids MG/L*
For anaerobic digestion only.
C-8
-------
APPENDIX D
DEFINITION OF OUTPUT PARAMETERS
-------
PRIMARY CLARIFIER
FLOW • Hydraulic flow race of Che wascewacer treatment
plane; expressed in million gallons per day (MGD).
PCE BOD - Concencracion of BOO. of primary clarifier
effluent (mg/1).
PCE TSS • Concentracion of cocal suspended solids of
primary clarifier effluenc (mg/1).
PS • Primary sludge; production race (Ibs/day), solids
content expressed in Ibs. of dry solids per Ib. of
sludge in terms of percencage (I) and flow rate
(gallons/day).
SL • Surface loading or overflow race of che primary
clarifier (gal/fc2/day).
D-2
-------
BIOLOGICAL PROCESS PARAMETERS
MAX MLSS • Maximum value of the mixed liquor suspended solids
concentration (mg/1).
MLVSS - Mixed liquor volatile suspended solids (%).
F/M • Food to microorganism ratio (dimensionless).
MCRT • Mean cell residence time of biological reactors (days).
SVI • Sludge volume index; defined as the volume in ml
occupied by one gram of mixed liquor solids after
30 minutes settling.
RAS • Return activated sludge; flow rate (MOD) and concen-
tration (mg/1).
WAS ' • Wasted activated sludge; mass flow rate (Ibs/day).
OET TIME - Hydraulic detention time, (hrs) and (days).
LOAD • Activated Sludge, Extended Aeration and Contact
Stabilization Systems - expressed in Ibs 8005
per 1000 ft3 of reactor volume (Ibs BOD^/1000 ft3).
- All Trickling Filter and ABF Systems - expressed in
Ibs BOD per 1000 ft3 of media volume (Ibs BOD./1000 ft3)
. RBC
surface
5'
2
systems - expressed in Ibs BOD per 1000 ft of media
ace (Ibs BODc/1000 ft2).
'5
OUR • Oxygen uptake rate (mg/l/hr).
O.RQD « Oxygen requirement (Ibs/day).
D-3
-------
SECONDARY CLARIFIER
DOB
EFF BOD
EFF TSS
EFF NO,
EFF PO ,-P
4
CLARIFIES LOAD
SEC. SLUDGE PROD
TOTAL SLUDGE PROD
Depth of blanket (ft). (Measured from surface)
Effluent concentration of BOD, (mg/1).
Effluent concentration of total suspended
solids (mg/1).
Effluent concentration of nitrate nitrogen (mg/1)
Effluent concentration of orthophosphates (mg/1).
Hydraulic loading of the secondary clarifier;
surface loading (gal/ft2/day) and weir loading
(gal/ft of weir length/day).
Sludge production from secondary clarifier per
day; expressed in Ibs. of total suspended solids
(Ibs/day) and in Ibs. of volatile suspended
solids (Ibs/day).
Total sludge production from both primary and
secondary systems per day; in terms of Ibs. of
TSS (Ibs/day). Ibs of VSS, (Ibs/day) and in
terms of flow rate (gal/day); it is characterized
by its solids content in terms of percent solids
(2 SOL).
D-4
-------
DIGESTER
TOTAL SLUDGE FLOW
VSS LOADING
MCBT
Z VSS RED.
RAW SLUDGE FLOW, GPD
Z SOLIDS RAW SLUDGE
Z VOLATILE SOLIDS,
RAW SLUDGE
DIGESTER TEMP. °c
Z SOLIDS, DIGESTER
LIQUOR
Z VOLATILE SOLIDS,
DIGESTER LIQUOR
GAS PRODUCTION,
FT3 X 1000
ALKALINITY AS CaCO-,
MG/L
VOLATILE ACIDS, MG/L
Total sludge flow rate into the primary digester
(gal/day); or as previously defined under the
title "Total Sludge Prod."
Volatile suspended solids loading to the primary
digesters expressed in Ibs of VSS loaded per ft3
of digester per day (Ibs/ft3/day).
Mean cell residence time in the primary digesters
(days).
Volatile suspended solids reduction (Z); in the
primary digesters.
Gallons of raw sludge pumped to the digester
each day.
Concentration of raw sludge being pumped to the
digester.
The volatile content of the raw sludge solids in
percent.
•
The temperature of the digester liquor in degrees
centigrade.
Concentration of digester solids in percent.
The volatile content of the digester sludge in
percent.
The actual gas production in cubic feet divided
by one thousand. For anaerobic digesters only.
The total alkalinity of the digester liquor
assumed to be calcium carbonate. For anaerobic
digesters only.
The volatile acid concentration in milligrams
per liter assumed to be acetic acid (CH.COOH).
D-5
-------
APPENDIX E
REPRESENTATIVE VALUES FOR OUTPUT PARAMETERS
-------
PRIMARY TREATMENT SYSTEM
LOU NORMAL HIGH
PARAMETERS LOADING LOADING LOADING
Surface Loading (GPDSF) 400 300 1500
Weir Loading (GPD/FT) 8000 20,000 40,000.
Detention Tine (Hrs.) 4.0 2.0 1.0
BOD. Percent Removal 40 25 15
TSS Percent Removal 70 50 30
E-2
-------
SECONDARY TREATMENT SYSTEM
Conventional Activated Sludge
PARAMETERS
MAX MLSS (MC/L)
HLVSS (Z)
F/M
JCRT (DAYS)
SVI
DET. TIME (BBS)
LB BOO/1000 FT3
OD& (MC/L/HJO
LOAD
• SFC (GPSFD)
-WEI1 (GPLFD)
LOW
LOADING
2500
60
0.10
20
100
8
20
10
NORMAL
LOADING
2500
75
0.30
7
100
6
50
20
HIGH
LOADING
<2500
85
0.40
3
>150
3
75
40
200
8000
400
12.000
600
16.000
E-3
-------
SECONDARY TREATMENT SYSTEM
Single Stage Activated Sludge for Nitrification
PARAMETERS
MAX MLSS (MG/L)
MLVSS (Z)
F/M
MCRT (DAYS)
SV1
DET. TIME (HRS)
LB BOD/1000 FT3
OUR (MG/L/HR)
CLARinER LOAD
- SFC (CPSFD)
•WEIR (GPLFD)
LOU
LOADING
2500
60
0.10
25
100
10
20
10
NORMAL
LOADING
2500
75
0.30
10
100
8
50
20
HIGH
LOADING
<2500
85
0.40
7
>150
4
75
40
200
8000
. 400
12,000
600
16,000
E-A
-------
SECONDARY TREATMENT SYSTEM
Activated Bio-Filter (Biological Reactor Performance page)
PARAMETERS
MAX MLSS (MG/L)
MLVSS (Z)
F/M
MCRT (DAYS)
SV1
DET. TIME (HRS)
LB BOD/1000 FT3
OUR (MG/L/HR)
CLARIFIER LOAD
- SFC (GPSFD)
-WEIR (CPLFD)
LOU
LOADING
2500
60
0.10
15
100
8
20
10
200
8000
NORMAL
LOADING
2500
75
0.30
6
100
6
50
20
400
12,000
HIGH
LOADING
<2500
85
0.40
3
>150
3
75
40
600
16,000
E-5
-------
SECONDARY TREATMENT SYSTEM
Extended Aeration
Extended Aeration Oxidation Ditch
PARAMETERS
MAX MLSS (MC/L)
MLVSS (Z)
F/M
MCRT (DAYS)
SV1
DET. TIME (HRS)
LB BOD/1000 FT3
OUR (MC/L/HR)
CLARIFTER LOAD
- SFC (CPSFD)
- WEIR (GPLFD)
LOW
LOADING
3000
60
0.10
40
100
36
5
5
NORMAL
LOADING
3000
65
0.15
30
100
24
15
10
HIGH
LOADING
<3000
75
0.2
20
150
12
25
25
200
8.000
400
12,000
600
16.000
E-6
-------
SECONDARY TREATMENT SYSTEM
Contact Stabilization
PARAMETERS
Contactor
MAX MLSS (MG/L)
MLVSS (2)
F/M
MCRT (DAYS)*
SV1
DET. TIME (MRS)
OUR (MC/L/HR)
LB BOD/1000 FT3
Reaeration Tank
MAX MLSS (MG/L)
F/M
Clarlfler Load
- SFC (CPSFD)
- WEIR (CPLFD)
Aggregate of contactor and reaeration tanks
LOU
LOADING
2500
55
0.60
20
100
6.0
15
40
10,000
0.10
200
8,000
NORMAL
LOADING
2500
70
0.90
7
100
3.0
30
•75
10,000
0.15
400
12,000
HIGH
LOADING
<2500
85
1.20
3
150
1.0
50
100
<7,000
0.20
600
16,000
E-7
-------
SECONDARY TREATMENT SYSTEM
Single Stage Trickling Filter
Two Stage Trickling Filter
Activated Bio-Filter (Secondary System Loading page)
LOU NORMAL HIGH
PARAMETERS LOADING LOADING LOADING
Single Stage Trickling Filter
FILTER LOADING (GPDSF) 200 800 1500
FILTER LOADING (#800/1000 FT3) 10 25 40
RECIRCULATION RATIO (Z) 0 100 200
Two Stage Trickling Filter (First Stage) and
Activated Bio-Filter (Secondary System Loading page)
FILTER LOADING (GPDSF) 200 800 1500
FILTER LOADING (OBOD/1000 FT3) 50 100 150
RECIRCULATION RATIO (2) 0 100 200
Tvo Stage Trickling Filter (Second Stage)
FILTER LOADING (GPDSF) 200 800 - 1500
FILTER LOADING (ttOD/1000 FT3) 10 20 30
RECIRCULATION RATIO (Z) 0 100 200
ALL TYPES
CLARIFIER LOADINGS - SURFACE
(GPDSF) 200 600 800
- WEIR
(GPD/FT) 8,000 15,000 20,000
E-8
-------
SECONDARY TREATMENT SYSTEM
Rotating Biological Contactors
PARAMETERS
STAGE LOADING
STAGE 1 (IBOD/1000 FT2)
TOTAL (JBOD/10CD FT2)
CLAR1FIER LOADINGS - SURFACE (GPDSF) 200
-WEIR (GPD/FT)
*Total BOD,
LOW
LOADING
1.0
0.5
') 200
8000
NORMAL
LOADING
2.0
1.0
600
15,000
HIGH
LOADING
3.5
1.5
800
20,000
E-9
-------
SECONDARY TREATMENT SYSTEM
Roughing Filter/Activated Sludge
PARAMETERS
Roughing Filter
FILTER LOADING (GFDSF)
FILTER LOADING (0BOD/1000 FT3)
RECIRCULATION RATIO (Z)
Activated Sludge
MAX MLSS (MG/L)
MLVSS (Z)
F/M
MCRT (DAYS)
SVI
DET. TIME (HRS)
LB BOD/1000 FT3
OUR (MG/L/HR)
CLARIFIER LOAD
- SFC (GPSFD)
- WEIR (GPLFD)
LOW
LOADING
800
50
0
2500
60
0.10
20
100
8
20
10
200
8000
NORMAL
LOADING
1500
100
100
2500
75
0.30
7
100
6
50
20
400
12,000
HIGH
LOADING
4000
300
200
<2500
85
0.40
3
>150
3
75
40
600
16,000
E-10
-------
SLUDGE DIGESTION SYSTEM
PARAMETERS
Aerobic Digesters (WAS only)
VSS LOADING (LB/FT3/DAY)
MCRT (DAYS)
2 VSS REDUCTION
LOU
LOADING
.05
30
60
NORMAL
LOADING
.10
15
40
HIGH
LOADING
.15
10
20
Anaerobic Digesters (Standard Rate)
VSS LOADING (LB/FT3/DAY) .05
MCRT (DAYS) 45
2 VSS REDUCTION 75
.10
30
60
.15
20
40
Anaerobic Digesters (High Rate)
VSS LOADING (LS/FT3/DAY)
MCRT (DAYS)
2 VSSS REDUCTION
.10
30
70
.:s
20
50
.40
15
30
E-ll
-------
APPENDIX F
DO'S AND DON'TS OF
COMPUTER. OPERATION
-------
DO'S AND DON'TS OF
COMPUTER OPERATION
DO NOT remove circuit boards in computer while power is on.
DO NOT turn the computer on unless there is a diskette in Drive A
or a hard disk is used.
DO NOT remove a diskette from a drive while the red "in use" light is on.
DO NOT hit control reset buttons while red "in use" light is on on
either diskette drive.
DO turn printer on and place it "on line" before running programs.
DO have paper in printer before turning it on.
DO NOT manually advance printer paper while printer is on—use LF
(line feed) or FF (form feed) buttons instead.
DO keep equipment in cool (<85°F), relatively dry area.
DO NOT expose diskettes to magnetic or electrical fields (such as
from electric motors), heat, or sunlight.
DO NOT touch grey shiny surface of diskette with fingers or other object.
DO keep diskettes in paper envelope when not in use.
DO handle diskettes carefully by plastic cover only.
DO NOT force diskettes into drives—they should enter smoothly with
little effort.
DO NOT leave diskettes stored in drives overnight.
F-2
-------
ZEZ> MATHEMATICAL- MODI
iMTRO , C AL. I R-OIRIM X A
RIRXMARY UIASTEUJATER
TREATMEIMT SYSTEM
APPENDIX 6
Prepared by ES Environmental Services,
by contract with Boise State
University, Boise, Idaho. Through a grant -from th«
Environmental Protection Agency, Region X,
Seattle Washington.
-------
DATE:
TIME: i
:FRZ
AVERAGE DRY WEATHER FLOW
PEAK DRY WEATHER FLOW
DESIGN FLOW
INFLUENT BOO
INFLUENT TSS
INFLUENT VSS
TEMPERATURE
TKN
ALKALINITY
PH
P04-P
MGDs 3
MGDs 5
MGDs 6
MG/Ls 210
MG/Ls 233
(%): 83
'Cs 22
MG/Ls 3O i
MG/Ls 10O
: 7 *
MG/Ls 8 *
DEFAULT VALUE USED
Pt-AIM~T COMF=* I QLJF*AT I OIM AIMD D Z MECIMS X OMS
DESIGN AVERAGE DAILY FLOW (MGD) : 5
DESIGN PEAK WET WEATHER FLOW (MGD): 1O
ZOIM
NUMBER OF ROUND CLARIFIERS: 2
DIMENSIONS EACH TOTAL
DIAMETER (FT): 6S
DEPTH (FT): 8.5
WEIR LTH (FT): 2OS
SFC AREA (FT2): 6636
205
6636
-------
DATE:
TIME:
X IMC5
TYPE OF DIGESTIONi ANAEROBIC
NUMBER OF PRIMARY DIGESTERS: 1
VOLUME (SAL) I 187OOO
DIBESTER HEATED Y
DIGESTER MIXED Y
NUMBER OF SECONDARY DIGESTERS* 1
VOLUME FOR DIGESTER «1 GAL: 1S7OOO
-------
EL CENTRO, CALIFORNIA units
MATHEMATICAL MODEL TIMEi I
BODl 210
TSS> 235
TEMP 22
FLOW
F6D
2.25
2.54
2. 83
3.13
3.42
3.71
4.00
4.29
4.59
4.88
S.17
!.46
5.76
6.05
6.34
6.63
6.92
7.22
7.51
7.8O
F-RXI1
*
* CLAR
« SURFACE »
* SPDSF *
339
383
426
472
515
559
603
646
692
735
779
823
868
912
955
999
1O43
1038
1132
1175
ARV
SVSTEM
. LOADINGS *
WEIR « SOLIDS' *
GDP/FT * */SF/DAY *
5487
6195
6902
7634
8341
9O48
9756
10463
11195
11902
12609
13317
14O48
14756
15463
16170
16878
17609
18317
19O24
.58
.66
.74
.82
.89
.97
1.05
1.12
1.20
1.28
1.35
1.43
1.51
1.59
1.66
1.74
1.82
*1.90
1.97
2.04
L-OADIIMC3S
*
DETN «
TIME *
MRS. »
4. SO
3.99
3.58
3.24
2.96
2.73
2.53
2.36
2.21
2.08
1.96
1.85
1.76
1.67
1.6O
1.53
1.46
1.40
1.35
1.30
-------
EL CENTRO, CALIFORNIA
I *
L *
r »
I *
5
14
fe
r
r
n
V)
29
59
98
17
46
76
05
34
63
92
22
SI
30
DATE:
TIMES s
BODs 210
TSSi 235
TEMP 22
AIMCE
* » *
Z REMOVAL *P.C. EFF MG/L * PRIMARY SLUDGE PROD. *
BOD * TSS * BOD * TSS «LBS TSS*LBS VSS* Z.SOL* GDP *
* * » » * *"**
55 65 95
54
51
49
47
45
44
42
41
4O
39
38
37
36
35
34
33
33
32
31
65
64
62
6O
58
56
55
53
51
50
49
47
46
45
44
43
42
41
4O
98
103
107
111
115
118
121
124
127
129
131
133
135
137
138
14O
141
143
144
82
82
84
89
94
99
103
107
111
114
117
121
124
127
129
132
134
136
139
141
2866
3236
3573
3810
4023
4223
4411
4588
4761
4918
5067
52O8
5347
5474
5596
5712
5823
5933
6O35
6132
237V
2686
2966
3162
3339
3505
3661
3808
3951
4082
4205
4323
4438
4544
4645
4741
4833
4924
5OO9
5O9O
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
5.71
6O19
6795
7502
8OOO
8448
8868
9263
9634
9996
10327
10639
10936
11227
11495
11751
11994
12228
12458
12672
12877
-------
APPENDIX H
ZONE SETTLING VELOCITY
-------
APPENDIX H
ZONE SETTLING VELOCITY
The zone settling velocity or rate of activated sludge settling is an
extremely important parameter In evaluating activated sludge system per-
formance. Obviously if the mixed liquor does not settle well then poor
performance can be expected. On the other hand, if the mixed liquor settles
well and the effluent quality is poor, then the probable cause is poor
clarifier hydraulics or clarifier overload.
The zone settling velocity is determined by measuring the settling
rate of the activated sludge reactor effluent In a one or two liter
graduated cylinder. The Interface height is measured at various time
Intervals (see work sheet), plotted on a graph, the slope estimated, and
then data is converted to feet per hour. Settling velocities g^n be
characterized as follows:
Condition Range, ft/hr
Poor <3
•
Fair 3-5
Good 6-9
Excellent >10
When evaluating a treatment plant, the final clarifier surface area is
also a significant element and should be used in conjunction with the zone
settling velocity. As an example, the reactor effluent solids could have
a settling rate of 3 feet per hour but at the same time the final clarifier
surface loading could be low enough to compensate for the poor settling.
There have been many theories and equations developed to determine the
required surface area or "B*T-t«m» surface loading based on zone settling
velocity. Many of these equations are highly theoretical and extremely
complex, and are beyond the scope of this manual.
A very simplified approach to determine the maximum final clarifier
surface loading is to multiply the zone settling velocity by 180. As an
example, if the zone settling was determined to be 5 ft/hr then the
-------
""""iTiiinn final clarifiar surface loading would be 5 x 180 * 900 gallons
per square foot per day. This is the ma-g^mum loading. If the average
to peak flow factor were 1.5 then the average loading would be 900/1.5 *
600 gallon* per square foot per day.
PHOCZDUHE (One Liter Graduate Method)
Measure the distance between each 100 ml mark and record in feet.
Fill the graduated cylinder with mixed liquor. If the mixed liquor
concentration is in excess of 3000 mg/1 use a stirring apparatus con-
sisting of 3 vertical elements long enough to reach the bottom of the
cylinder. The stirrer should be connected to a clock motor that rotates
at about 12 revolutions per hour.
Record the height of the interface at the time intervals indicated
on the work sheet. After data is recorded, plot the data graph sheet
provided and draw the best fit curve. Then draw a straight line through
the first part of the curve starting at zero time. Note where the
approximate tangent point is on the curve, then draw a horizontal line
from that point to determine the interface height at that time. Record
this data and compute the zone settling as indicated on the work sheet.
Note the two sheets marked "sample" to be used as an example. The next
two sheets are forms that can be copied and utilized for the zone
settling velocity test.
-------
FIGURE
ZONE SETTLING VELOCITY
WORK SHEET
Time Interface
minutes height, mis
1
2
3
4
5
7
9
11
13
15
20
25
30
Computations
(1000 - tang. point)(100ml dist)(60)
Date —
Location
Analyst
Distance between
IQQmla ft.
MLSS cone. _
tangent point
time
.mg/L
ml
minutes
time min
- 2SV, ft/hr
(1000 -.
J(0.8)
ZSV, ft/hr
(ZSVH179.5) -.
( )<179.5) -.
maximum surface loading gpdsf
.maximum surface loading gpdsf
dOOOXml settled, 3Qmin)
MLSS, mg/L
• SVI, g/100ml
(1000X
SVI, g/100ml
ES9 ES ENVIRONMENTAL SERVICES
-------
FIGURE
ZONE SETTLING VELOCITY
1000
900
800
« 700
E
o> 600
"3
I 500
CD
- 400
300
200
100
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time Minutes
ES* ES_ENV!RONMENTAL SERVICES
-------
FIGURE
100
ZONE SETTLING VELOCITY
* I I I I I I
024
6 8 1(\ 12 14 16 18 20 22 24 26 28 30
Time Minutes
&
2&0 MLS
-------
FIGURE
ZONE SETTLING VELOCITY
WORK SHEET
Time
minutes
Interface
height, mis
Date
Location
Analyst
A/a
Distance between
mia^. //g ft.
Computations
(1000 - tang, poin
MLSS conc.^£2_mg/L
tangent paint 2&0 mi
minutes
(
(ZSVX179.5) -.
ft/hr
.maximum surface loading gpdsf
.maximum surface loading gpdsf
dOOOHml settled, 30min) ^
MLSS, mg/L
(1000M
)
(
.SVI, g/100ml
ES2 ES ENVIRONMENTAL SERVICES
------- |