ORIENTATION TO WASTEWATER
TREATMENT OPERATION
CLEA
TRAINING MANUAL
FEDERAL WATER QUALITY ADMINISTRATION
DEPARTMENT OF THE INTERIOR
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ROSTER
ORIENTATION TO WASTEWATER TREATMENT
4/3/72-4/7/72
~f~BEEKON F, GREG LEE LAUZEN, KENT01J L.
trnvi roninsntal Protection Agency Environmental Protection Agency
1735 Baltimore 1200 6th Ave.
Kansas City, MO 64108 Seattle, WA 98116
3EN0IT, PHILIP E.
U.S.D.A. Forest Service
444 E. Bornta
San Dimas, CA 91773
BOOTH, LARRY C.
U . S. Coast Guard
Annette, AK 99920
BOLOSAN, ONOFRE
U. S. Coast Guard, 14th C.G. Dist.
677 Ala Moana Blvd.
Honolulu, HI 96813
BUGENIG, LEWIS W.
U. S . Coast Guard
ECV
P.O. Box 3-5000
Juneau, AK 99801
CARSON, THOMAS G.
U. S. Coast Guard
Juneau, AK 99801
LIEBLER, JOHN W.
Dept. of Interior, National Park Service
Mt. Rainier
Longmire, WA
LUM, DAVID
U. S. Coast Guard
677 Ala Moana Blvd
Honolulu, HI 9681 3
MERRITT, LAGRANDE
Environmental Protection Agency
200 S. W. 35th Street
Corvallis, OR 97330
OLMSTEAD, CECIL
Olympic National Park
600 East Park
Port Angeles, WA 98362
PONTON, GERALD
U. S. Coast Guard
Ketchikan, AK 99901
FARRIS, MARTIN W.
U. S. Coast Guard
Annette, AK 99920
FUJII , DAVID M.
Self-employed
11 E. Delaware
Chicago, Illinois 60611
KOLLIAS, VAN A.
Department of Environmental
1234 S. W. Morrison
Portland, OR
JAKSIC, BORISLAV
"INCE"
Banja Luka, Yugoslavia
KINGSBURY, W. ALLEN
U. S. Public Health Service
50 Fulton St.
San Francisco, CA 94102
REYNOLDS, GEORGE
U. S. Forest Service, Umpqua National Fores 1
Box 1008
Roseburg, OR 97470
SARGENT, JAMES H.
Environmental Protection Agency
1421 Peachtree St. N. E.
Atlanta, GA 30309
Quail ty SCHURR, LARRY M.
Dept. of Environmental Quality
8148 S.W. Beaverton-Hillsdale Hwy.
Portland, OR
SHAW, DENNIS J.
U. S. Coast Guard
Ketchikan, AK 99901
TATE, CLIFFORD E.
Dept. of Interior, U.S.
Olympic National Park"
600 E. Park Ave.
Port Angeles, WA
National Park Servic
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ORIENTATION TO WASTEWATER TREATMENT OPERATION
April 3-7, 1972
AGENDA
DIRECTOR: D. S, May
MODERATOR: J. F. Woolev
DATE & TIME
SUBJECT
Outli ne
No.
SPEAKER
Monday, April 3
8:30 - 8:45
8:45 - 9:00
9:00 - 9:15
9:15 - 10:00
10:00 - 10:30
10:30 - 11:30
11:30 - 12:30
12:30 - 1:30
1:30 - 2:15
2:15 - 3:00
3:00 - 3:15
3:15 - 4:00
4:00 - 4:30
Tuesday, April 4
8:30 - 9:15
9:15 - 10:00
10:00 - 10:30
10:30 - 11:30
11:30 - 12:30
12:30 - 1:30
Regi strati on
Welcome
Objectives of Course
Laboratory Tour
Break
The Freshwater Environment
Water Quality Criteria
Lunch
Definitions and Terms
1
2
47
Wastewater Treatment
Natural Phenomena
The Result of 4
Break
Screening and Grit Removal
Discussion
Flow Measurement Devices
The Sedimentation Process
Break
7,8
9
10,11
Determining Efficiency of Settling 26,
Tanks and Clarifiers 12
Anaerobic Digestion
Lunch
14
J. F. Wooley
D. S. May
D. S. May
Staff
J. F. Wooley
D. S. May
D. S. May
J. F. Wooley
L. J. Nielson
Staff
L. J. Nielson
L. J. Nielson
D. S. May
D. S. May
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-2
1:30 - 2:15
2:15 - 3:00
3:00 - 3:15
3:15 - 4:30
Wednesday, April 5
8:30 - 9:30
9:30 - 10:00
10:00 - 10:30
10:30 - 11:00
11:00 - 12:30
12:30 - 1:30
1:30 - 2:45
2:45 - 3:00
3:00 - 4:30
Thursday, April 6
8:30 - 9:15
9:15 - 10:00
10:00 - 10:30
10:30 - 11:30
11:30 - 12:30
Factors Affecting Digester 16
Efficiency
Testing as a Tool for Digester 28
Operations
Break
Lab Demonstration
Trickling Filters 21
The Activated Sludge Process 19
Break
Activated Sludge Modifications
Significance of Bacteriological 29
Data
Lunch
Determination of Bacteriological 30,
Contamination 31
Break
Tour - Wastewater Treatment Plant
Stabilization Lagoons 22
Test Procedures and Use of Results
in Operation of Secondary Treatment
Processes
Break
Effluent Disinfection 41
Chlorination - Determination of 40
Dosage Requirements and Testing
Methods
L. J. Nielson
D. S. May
Staff
L. J. Nielson
D. S. May
D. S. May
D. S. May
D. S. May
J. F. Wooley
D. S. May
D. J. Hernandez
C. Carlson
12:30 - 1:30
Lunch
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-d
1:30 - 3:00
3:00 - 3:15
3:15 - 4:30
Friday, April 7
8:30 - 9:15
9:15 - 10:00
10:00 - 10:30
10:30 - 11:00
11:00 - 11:30
11:30
Package Treatment Plants
Break
The Treatment Plant Operator,
Laboratory Control, and Record
Keeping
Discussion
Tertiary Waste Treatment
Break
25
38
Methods Which May be Used to Detect 42
Industrial Waste Problems
Discussion and Course Evaluation
Course Closure
Neptune Microfloc
Representati ve
D. S. May
Staff
J. F. Wooley
L. J. Nielson
Staff
L. J. Nielson
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ORIENTATION TO WASTEWATER
TREATMENT OPERATION
This course is designed for individuals in local. State
and regional programs who are, or expect to be, involved
in designing and conducting operator training courses
The course stresses technical content of operator
interest. Course content is intended to be used in the
preparation of lesson plans for operator training or as
background information for discussion purposes
The manuals are prepared in limited numbers for use
of the class, and hence should not be cited in
bibliographies as appearing periodically
U. S. DEPARTMENT OF THE INTERIOR
Federal Water Quality Administration
TRAINING PROGRAM
JANUARY 1971
-------
FOR EW ORD
These manuals are prepared for reference use of students enrolled in
scheduled training courses of the Water Quality Office, Environmental
Protection Agency.
Vuz to thz l^m^tzd ava^-Zab-cl-tty o & thz rna.nua.Z6,
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pubZ4.ccLt.L0n.
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TRAINING
PROGRAM
Through the Water Quality Office, Environmental Protection Agency conducts
programs of research, technical assistance, enforcement, and technical
training for water pollution control.
Training is available at five installations of the Agency. These are the
National Training Center located at the Robert A. Taft Sanitary Engineering
Center in Cincinnati, Ohio, the Robert S. Kerr Water Research Center, Ada,
Oklahoma, the Southeast Water Laboratory, Athens, Georgia, the Pacific
Northwest Water Laboratory, Corvallis, Oregon, and the Hudson-Delaware
Basins Office, Edison, New Jersey.
The objectives of the Training Program are to provide specialized training in
the field of water pollution control which will lead to rapid application of new
research findings through updating of skills of technical and professional
personnel, and to train new employees recruited from other professional or
technical areas in the special skills required. Increasing attention is being
given to development of special courses providing an overview of the nature,
causes, prevention, and control of water pollution.
Scientists, engineers, and recognized authorities from other Agency programs,
from other government agencies, universities, and industry supplement the
training staff by serving as guest lecturers. Most training is conducted in the
form of short-term courses of one or two weeks' duration. Subject matter
includes selected practical features of plant operation and design, and water
quality evaluation m field and laboratory. Specialized aspects and recent
developments of sanitary engineering, chemistry, aquatic biology, microbiology,
and field and laboratory techniques not generally available elsewhere, are included.
The primary role and responsibility of the States in the training of wastewater
treatment plant operators are recognized. Technical support of operator-training
programs of the States is available through technical consultations in the planning
and development of operator-training courses. Guest appearances of instructors
from the Environmental Protection Agency, and the loan of instructional materials
such as lesson plans and visual training aids, may be obtained through special
arrangement. These training aids, including reference training manuals, may be
reproduced freely by the states for their own training programs. Special categories
of training for personnel engaged in treatment plant operations may be developed
and made available to the States for their own further production and presentation.
An annual Bulletin of Courses is prepared and distributed by the Water Quality
Office. The Bulletin includes descriptions of courses, schedules, application
blanks, and other appropriate information. Organizations and interested indi-
viduals not on the mailing list should request a copy from one of the training centers
mentioned above.
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ENVIRONMENTAL PROTECTION AGENCY
WATER QUALITY OFFICE
DIVISION OF MANPOWER AND TRAINING
R. F. Guay, Director
Training Grants Branch
Manpower Planning Branch
State and Local Manpower
Development Branch
Direct Training Branch
Office of Environmental A ctivities
National Training Center
Robert A. Taft Sanitary
Engineering Center
4676 Columbia Parkway
Cincinnati, OH 45226
REGIONAL MANPOWER DEVELOPMENT AND TRAINING OFFICES
Northeast Region
Manpower and Training Office
John F. Kennedy Federal Building
Room. 2303
Boston, MA 02203
South Central Region
Manpower and Training Office
Robert S. Kerr Water Research Center
P. O. Box 1198
Ada, OK 74820
Manpower and Training Office
Hudson-Delaware Basins Office
Edison, NJ 08817
Middle Atlantic Region
Missouri Basin Region
Manpower and Training Office
911 Walnut Street
Kansas City, MO 64106
Manpower and Training Office
918 Emmett Street
Charlottesville, VA 22901
Southeast Region
Great Lakes Region
Manpower and Training Office
33 E. Congress Parkway
Chicago, IL 60605
Manpower and Training Office
Southeast Water Laboratory
College Station Road
Athens, GA 30601
Ohio Basin Region
Manpower and Training Office
Federal Office Building
Room 7027
Cincinnati, OH 45226
Southwest Region
Manpower and Training Office
620 Central Avenue
Alameda, CA 94501
Pacific Northwest Region
Manpower and Training Office
Pacific Northwest Water Laboratory
200 South 35th Street
Corvallis, OR 97330
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CONTENTS
Title or Description Outline Number
The Aquatic Environment 1
Water Quality Criteria 2
Wastewater Treatment Schematic, Functions, Options 3
Wastewater Treatment - The Result of Natural Phenomena 4
Unit Operations in Waste Treatment 5
Wastewater Treatment Plant Safety Practices 6
Screening - Methods and Purposes 7
Grit Removal - Principles and Methods 8
Flow Measurement Devices 9
Sedimentation Basins in Wastewater Treatment 10
Sedimentation Tank Equipment 11
Causes of Reduced Efficiency in Primary Clarification 12
Settling Tank Operations , 13
Anaerobic Process Principles 14
Anaerobic Industrial Waste Applications 15
Factors Affecting Digester Efficiency 16
Aerobic Digestion 17
Activated Sludge Waste Treatment Process Variations and Modifications 19
Case Histories Effluent Excellence from Presently Available 20
Secondary Treatment Processes
Trickling Filters 21
Experience in the Use of Raw Sewage Lagoons 22
Sampling in Water Quality Studies 24
Sampling in Treatment Plant Operations 25
Determining Efficiency of Settling Tanks and Clarifiers 26
173.8.71
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2
CONTENTS
Title or Description Outline Number
Testing as a Tool for Digest Operation 28
Significance of Bacteriologic Data 29
Examination of Water for Coliform and Fecal 30
Streptococcus Groups
Membrane Filter Laboratory and Field Procedures 31
Dissolved Oxygen Determination (DO) - I' 32
Azide Modification, Iodometric Titration
Dissolved Oxygen Determination - n 33
Electronic Measurements
BOD Procedures for Treatment Plant Operations 34
Effect of Some Variables on the BOD Test 35
Chemical Oxygen Demand and COD/BOD Relationships 36
Pumps Maintenance 37
Ultimate Disposal to the Environment 38
Chlorine Determinations and Their Interpretation 40
Wastewater Disinfection 41
Methods Which May Be Used to Detect Industrial Waste Problems 42
The Model Sewer Ordinance 43
Training for Wastewater Treatment Plant Operations 45
Evaluation of Wastewater Treatment Programs 46
Glossary 47
Computation Check Charts (5) 48
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THE AQUATIC ENVIRONMENT
Part 1- The Nature and Behavior of Water
I INTRODUCTION
The earth is physically divisible into the
lithosphere or land masses, and the
hydrosphere which includes the oceans,
lakes, streams, and subterranean waters.
A Upon the hydrosphere are based a number
of sciences which represent different
approaches. Hydrology is the general
science of water itself with its various
special fields such as hydrography,
hydraulics, etc. These m turn merge
into physical chemistry and chemistry.
B Limnology and oceanography combine
aspects of all of these, and deal not only
with the physical liquid water and its
various naturally occurring solutions and
forms, but also with living organisms
and the infinite interactions that occur
between them and their environment.
C Water quality management, including
pollution control, thus looks to all
branches of aquatic science in efforts
to coordinate and improve man's
relationship wLth his aquatic environment.
II SOME FACTS ABOUT WATER
A Water is the only abundant liquid on our
planet. It has many properties most
unusual for liquids, upon which depend
most of the familiar aspects of the world
about us as we know it.
TABLE 1
UNIQUE PROPERTIES OF WATER
Property
Significance
Highest heat capacity (specific heat) of any
solid or liquid (except NH^)
Stabilizes temperatures of organisms and
geographical regions
Highest latent heat of fusion (except NH^)
Thermostatic effect at freezing point
Highest heat of evaporation of any substance
Important in heat and water transfer of
atmosphere
The only substance that has its maximum
density as a liquid (4°C)
Fresh and brackish waters have maximum
density above freezing point. This is
important in vertical circulation pattern
in lakes.
Highest surface tension of any liquid
Controls surface and drop phenomena,
important in cellular physiology
Dissolves more substances in greater
quantity than any other liquid
Makes complex biological system possible.
Important for transportation of materials
in solution.
Pure water has the highest di-electric
constant of any liquid
Leads to high dissociation of inorganic
substances m solution
Very little electrolytic dissociation
Neutral, yet contains both H+ and OH ions
Relatively transparent
Absorbs much energy in infra red and ultra
violet ranges, but little in visible range.
Hence "colorless"
BI.2lb.2 70
1-1
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The Aquatic Environment
B Physical Factors of Significance
2 Density
1 Water substance
Water is not simply "l^O" but in
reality is a mixture of some 33
different substances involving three
isotopes each of hydrogen and oxygei^
(ordinary hydrogen H*, deuterium H ,
and tritium H , ordinary oxygen
oxygen 17, and oxygen 18) plus 15 known
types of ions. The molecules of a
water mass tend to associate themselves
as polymers rather than to remain as
discrete units. (See Figure 1)
Temperature and density: Ice.
Water is the only known substance
in which the solid state will float
on the liquid state. (See Table 2)
SUBSTANCE OF WATER
1-2
Figure 1
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The Aquatic Environment
TABLE 2
EFFECTS OF TEMPERATURE ON DENSITY
OF PURE WATER AND ICE*
Temperature (°C) Density
Water
Ice **
-10
.99815
.9397
- 8
.99869
.9360
- 6
.99912
.9020
- 4
.99945
. 9277
- 2
.99970
.9229
0
.99987
.9168
2
.99997
4
1.00000
6
.99997
8
.99988
10
0.00073
* Tabular values for density, etc., represent
statistical estimates, by various workers
rather than absolute values, due to the
variability of water.
** Regular ice is known as "ice I". Four or
more other "forms" of ice are known to
exist (ice II, ice III, etc. ), having densities
at 1 atm. pressure ranging from 1. 1595
to 1.67. These are of extremely restricted
occurrence and may be ignored in most
routine operations.
This ensures that ice usually
forms on top of a body of water
and tends to insulate the remain-
ing water mass from further loss
of heat. Did ice sink, there
could be little or no carryover of
aquatic life from season to season
in the higher latitudes. Frazil or
needle ice forms colloidally at a
few thousandths of a degree
below 0° C. It is adhesive and
may build up on submerged objects
as "anchor ice", but it is still
typical ice.
1) Seasonal increase in solar
radiation annually warms
surface waters in summer
while other factors result in
winter cooling. The density
differences resulting estab-
lish two classic layers* the
epilimmon or surface layer,
and the hypolimnion or lower
• layer, and in between is the
thermocline or shear-plane.
2) While for certain theoretical
purposes a thermocline is
defined as a zone in which the
temperature changes one
degree centigrade for each
meter of depth, in practice,
any transitional layer between
two relatively stable masses
of water of different temper-
atures (and probably other
qualities too) may be regarded
as a thermocline.
3) Obviously the greater the
temperature differences
between epilimmon and
hypolimnion and the sharper
the gradient in the thermocline,
the more stable will the
situation be.
4) From information given above,
it should be evident that while
the temperature of the
hypolimnion rarely drops
much below 4° C, the
epilimmon may range from
0° C upward.
5) It should also be emphasized
that when epilimmon and
hypolimnion achieve the same
temperature, stratification no
longer exists, and the entire
body of water behaves
hydrologically as a unit, and
tends to assume uniform
chemical and physical
characteristics. Such periods
are called overturns and
1-3
-------
The Aquatic Environment
usually result in considerable
water quality changes of
physical, chemical, and
biological significance.
6) When stratification is present,
however, each layer behaves
relatively independently, and
considerable quality differences
may develop.
7) Thermal stratification as
described above has no
reference to the size of the
water mass, it is found in
oceans and puddles.
8) The relative densities of the
various isotopes of water also
influence its molecular com-
position. For example, the
lighter °16 tends to go off
first in the process of
evaporation, leading to the
relative enrichment of air by
C>i0 and the enrichment of
water by and O^g. This
can lead to a measurably
higher 0lb content in warmer
climates. Also, the temper-
ature of water in past geologit
ages can be closely estimated
from the ratio of O^g in the
carbonate of mollusc shells.
b Dissolved and/or suspended solids
may also affect the density of
natural waters.
TABLE 3
EFFECTS OF DISSOLVED SOLIDS
ON DENSITY
Dissolved Solids
Density
(Grams per liter)
(at 40C)
0
1.00000
1
1.00085
2
1.00169
3
1.00251
10
1.00818
35 (mean for sea water) 1.02822
c Density caused stratification
1) Density differences produce
stratification which may be
permanent, transient, or
seasonal.
2) Permanent stratification
exists for example where
there is a heavy mass of
brine in the deeper areas of
a basin which does not respond
to seasonal or other changing
conditions.
3) Transient stratification may
occur with the recurrent
influx of tidal water in an
estuary for example, or the
occasional influx of cold
muddy water into a deep lake
or reservoir.
4) Seasonal stratification involves
the annual establishment of
the epilimnion, hypolimnion,
and thermocline as described
above. The spring and fall
overturns of such waters
materially affect biological
productivity.
5) Density stratification is not
limited to two-layered systems,
three, four, or even more
layers may be encountered in
larger bodies of water.
2 The viscosity of water is greater at
lower temperatures (see Table 4).
This is important not only in situations
involving the control of flowing water
as in a sand filter, but also since
overcoming resistance to flow gen-
erates heat, it is significant in the
heating of water by internal friction
from wave and current action.
Living organisms more easily support
themselves in the more viscous
(and also denser) cold waters of the
arctic than in the less viscous warm
tropical waters.
1-4
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The Aquatic Environment
TABLE 4
VISCOSITY OF WATER (In millipoises at 1 atm)
Temp, o c
Dissolved solids in g/ L
0
5
10
30
-10
26.0
- 5
21.4
0
17.94
18. 1
18.24
18.7
5
15. 19
15.3
15.5
16.0
10
13. 10
13.2
13.4
13.8
30
o
o
CO
8. 1
8.2
8.6
100
GO
CM
Surface tension has been reported
from 34 to 160 atm. This has
biological as well as physical sig-
nificance. Organisms whose body
surfaces cannot be wet by water can
either ride on the surface film, or in
some instances may be "trapped" on
the surface film and be unable to
re-enter the water.
Incident solar radiation is the prime
source of energy for virtually all
organic and most inorganic processes
on earth. For the earth as a whole,
the total amount (of energy) received
annually must exactly balance that
lost by reflection and radiation into
space if climatic and related con-
ditions are to remain relatively
constant over geologic time.
a For a given body of water,
immediate sources of energy
include in addition to solar
irradiation: terrestrial heat,
transformation of kinetic energy
(wave and current action) to heat,
chemical and biochemical
reactions, convection from the
atmosphere, and condensation of
water vapor.
b The proportion of light reflected
depends on the angle of incidence,
the temperature, color, and other
qualities of the water. In general,
as the depth increases arithmet-
ically, the light tends to decrease
geometrically. Blues, greens,
and yellows tend to penetrate most'
deeply while ultra violet, violets,
and orange-reds are most quickly
absorbed. On the order of 90%
of the total illumination which
penetrates the surface film is
absorbed in the first 10 meters of
even the clearest water, thus
tending to warm the upper layers.
5 Water movements
a Waves or rhythmic movement
The best known are traveling
waves caused by wind. These are
effective only against objects near
the surface. They have little
effect on the movement of large
masses of water.
Standing waves or seiches occur
in lakes, estuaries, and other
enclosed bodies of water, but are
seldom large enough to be
observed. An "internal wave or
seich" is an oscillation m a
submersed mass of water such
as a hypolimnion, accompanied
by compensating oscillation in the
overlying water such that no
significant change in surface level
is detected. Shifts in submerged
water masses of this type can have
severe effects on the biota and
also on human water uses where
withdrawals are confined to a given
depth. Descriptions and analyses
of many other types and sub-types
of waves and wave-like movements
may be found in the literature.
1-5
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The Aquatic Environment
b Tides
Tides are the longest waves known
in the ocean, and are evident along
the coast by the rhythmic rise and
fall of the water. While part and
parcel of the same phenomenon, it
is often convenient to refer to the
rise and fall of the water level as
"tide", and to the accompanying
currents as "tidal currents".
Tides are basically caused by the
attraction of the sun and moon on
water masses, large and small,
however, it is only in the oceans
and certain of the larger lakes that
true tidal action has been demonstrated.
The patterns of tidal action are
enormously complicated by local
topography, interaction with seiches,
and other factors. The literature
on tides is very large.
c Currents (except tidal currents)are
arhythmic water movements which
have had major study only in
oceanography They primarily are
concerned with the translocation of
water masses. They may be
generated internally by virtue of
density changes, or externally by
wind or terrestrial topography.
Turbulence phenomena or eddy
currents are largely responsible for
lateral mixing in a current. These
are of far more importance in the
economy of a body of water than
mere laminar flow.
d Coriolis force is a result of inter-
action between the rotation of the
earth, and the movement of masses
or bodies on the earth. The net
result is a slight tendency for moving
objects to veer to the right in the
northern hemisphere, and to the
left in the southern hemisphere.
While the result in fresh waters is
usually negligible, it may be con-
siderable in marine waters. For
example, other factors permitting,
there is a tendency in estuaries for
fresh waters to move toward the
ocean faster along the right bank,
while salt tidal waters tend to
intrude farther inland along the
left bank. Effects are even more
dramatic in the open oceans.
6 The pH of pure water has been deter-
mined between 5. 7 and 7. 01 by various
workers. The latter value is most
widely accepted at the present time.
Natural waters of course vary widely
according to circumstances.
C The elements of hydrology mentioned
above represent a selection of some of
the more conspicuous physical factors
involved in working with water quality.
Other items not specifically mentioned
include: molecular structure of waters,
interaction of water and radiation,
internal pressure, acoustical charac-
teristics, pressure-volume-temperature
relationships, refractivity, luminescence,
color, dielectrical characteristics and
phenomena, solubility, action and inter-
actions of gases, liquids and solids,
water vapor, ices, phenomena of
hydrostatics and hydrodynamics m general.
REFERENCES
1 Buswell, A.M. and Rodebush, W.H.
Water. Sci. Am. April 1956.
2 Dorsey, N. Ernest. Properties of
Ordinary Water - Substance.
Reinhold Publ. Corp. New York,
pp. 1-673. 1940.
3 Hutcheson, George E. A Treatise on
Limnology. John Wiley Company.
1957.
1-6
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THE AQUATIC ENVIRONMENT
Part 2: The Aquatic Environment as an Ecosystem
I INTRODUCTION
Part 1 introduced the lithosphere and the
hydrosphere. Part 2 will deal with certain
general aspects of the biosphere, or the
sphere of life on this earth, which photo-
graphs from space have shown is a finite
globe in infinite space.
This is the habitat of man and the other
organisms. His relationships with the
aquatic biosphere are our common concern.
II THE BIOLOGICAL NATURE OF THE
WORLD WE LIVE IN
A We can only imagine what this world
must have been like before there was life.
B The world as we know it is largely shaped
by the forces of life.
1 Primitive forms of life created organic
matter and established soil.
2 Plants cover the lands and enormously
influence the forces of erosion.
3 The nature and rate of erosion affect
the redistribution of materials
(and mass) on the surface of the
earth (topographic changes).
4 Organisms tie up vast quantities of
certain chemicals, such as carbon
and oxygen.
5 Respiration of plants and animals
releases carbon dioxide to the
atmosphere in influential quantities.
6 CO^ a^ects the heat transmission of
the atmosphere.
C Organisms respond to and in turn affect
their environment. Man is one of the
most influential.
IH ECOLOGY IS THE STUDY OF THE
INTERRELATIONSHIPS BETWEEN
ORGANISMS, AND BETWEEN
ORGANISMS AND THEIR ENVIRONMENT.
A The ecosystem is the basic functional
unit of ecology. Any area of nature that
includes living organisms and nonliving
substances interacting to produce an
exchange of materials between the living
and nonliving parts (Odum, 1959),
1 From a functional standpoint, an
ecosystem has two component parts.
(Figures 1, 2, 3)
a Autotrophic (self-nourishing)
organisms are able to fix light
energy and manufacture food from
simple inorganic substances.
b Heterotrophic (other-nourishing)
organisms utilize, rearrange,
and decompose the complex
materials synthesized by the
autotrophs.
2 From a structural standpoint, it is
convenient to recognize four con-
stituents as comprising an ecosystem.
a Abiotic substances are basic or
essential mineral elements and
compounds.
b Autotrophic (holophytic) organisms
are the producers, largely the
green plants.
c Heterotrophic (or holozoic)
organisms are chiefly animals
that ingest or consume other
organisms or particulate organic
matter.
BI. 21b. 2 70
1-7
-------
NON-ESSENTIAL
COMPONENTS
ESSENTIAL COMPONENTS
CARNIVORES
SCAVENGERS
CONSUMERS
SAPROBES
SECONDARY
DECOMPOSERS
TRANSFORMERS
MINERALIZED
NUTRIENTS
WORMS
SNAILS
FLYING
INSECTS
TERMINAL
J (detritus"
EFFLUENT
DETRITUS
vNON-LIVING
COMPONENTS
LIVING ,, ,r
COMPONENTS
PRINCIPAL STEPS AND COMPONENTS IN THE TRICKLING FILTER ECOSYSTEM
FROM COOKE, ECOLOGY. 40(2) 1939
BI ECO pi. 1 7 58
-------
The Aquatic Environment
I *§2? " ^§1 S&T vi^
I -e-^s. (V
Figure 2. Diagram of the pond ecosystem. Basic units are as follows. I, abiotic substances—basic inorganic and
organic compounds, IIA, producers—rooted vegetation, IIB, producers-phytoplankton. III-1A, primary consumers
(herbivores)—bottom forms, III-IB, primary consumers (herbivores)— zooplanVton, III-2, secondary consumers (car-
nivore!); III-3, tertiary consumers (secondary carnivores), IV, decomposers—bactena and fungi of decay.
d Decomposers are heterotrophic
organisms, chiefly bacteria and
fungi that return or reduce the
complex compounds of dead
protoplasm to their original
mineral condition.
Second - Plant eating animals
(herbivores) depend on the
producer organisms for food.
Third - Primary carnivores,
animals which feed on herbivores.
B Functioning of the Ecosystem
1 A food chain is the transfer of food
energy from plants through a series
of organisms with repeated eating
and being eaten. Food chains are not
isolated sequences but are inter-
connected.
d Fourth - Secondary carnivores
feed on primary carnivores.
e Last - Ultimate carnivores are
the last or ultimate level of
consumers.
4 Total assimilation
2 A food web is the interlocking pattern
of food chains in an ecosystem.
(Figure 1) In complex natural com-
munities, organisms whose food is
obtained by the same number of steps
are said to belong to the same trophic
(feeding) level.
3 Trophic levels
a First - Green plants (producers)
(Figure 4)fix biochemical energy and
synthesize basic organic substances.
The amount of energy which flows
through a trophic level is distributed
between the production of biomass
and the demands of respiration in a
ratio of approximately 1-10.
5 Trophic structure of the ecosystem
The interaction of the food chain
phenomena (with energy loss at each
transfer) results in various com-
munities having definite trophic
1-9
-------
The Aquatic Environment
Light
i\ if.
Nutrient
supply
Phytoplankton
Zooplankton
Predatory
animals
Death and decay
Bacterial
action
> t
Crabs
Mollusks
Worms
TWriC LEVSL >
IREUB*0H(3>
HtTifcCrtBOfH*
- TK3PTOC LEVEL I • I
icarjttto«u>
Figure 3. A MARINE ECOSYSTEM (After Clark, 1954 and Patten, 1966)
1-10
AUTOTfcOnU
ouTaor cnex trophic lkvel i
KXIW.I
Krirxnt
OUusi rh^si Ziii
(OaCOHKMZU ArfD 0*
CARHTVOUl WOCH OffTADI
pooo raoji all raonoc ltviui
-------
The Aquatic Environment
(a)
Decomposers (1
A
Carnivores (Secondar
Carnivores (Primary
Herbivores
| Producers |
(b)
1
(c)
1
.. vM/r/// /
TU/V //fill
1 1 1
\/J/>/ i J ! 1 ) ) / f / /Iff ) ) f\
Figure 4. HYPOTHETIC^ L PYRAMIDS of
(a) Numbers of individuals, (b) Biomass, and
(c) Energy (Shading Indicates Energy Loss).
structure or energy levels. Trophic
structure may be measured and
described either in terms of the
standing crop per unit area or in terms
of energy fixed per unit area per unit
time at successive trophic levels.
Trophic structure and function can be
shown graphically by means of
ecological pyramids (Figure 4).
B Periphyton (or aufwuchs) - The
communities of microscopic organisms
associated with submerged surfaces of
any type or depth. Includes bacteria,
algae, protozoa, and other microscopic
animals, and often the young or
embryonic stages of algae and other
organisms that normally grow up to
become a part of the benthos (see below).
Many planktonic types will also adhere
to surfaces as periphyton, and some
typical periphyton may break off and
be collected as plankters.
C Benthos are the plants and animals living
on, in, or closely associated with the
bottom. They include plants and
invertebrates.
D Nekton are the community of strong
aggressive swimmers of the open waters,
often called pellagic. Certain fishes,
whales, and invertebrates such as
shrimps and squids are included here.
E The marsh community is based on
larger "higher" plants, floating and
emergent. Both marine and freshwater
marshes are areas of enormous bio-
logical production.
IV BIOTIC COMMUNITIES
A Plankton are the macroscopic and
microscopic animals, plants, bacteria,
etc., floating free in the open water.
Many clog filters, cause tastes, odors,
and other troubles in water supplies.
Eggs and larvae of larger forms are
often present.
1 Phytoplankton are plant-like. These
are the dominant producers of the
waters, fresh and salt, "the grass of
the seas".
2 Zooplankton are animal-like. Includes
many different animal types, range
in size from minute protozoa to
gigantic marine jellyfishes.
V PRODUCTIVITY
A The biological resultant of all physical
and chemical factors is the quantity of
life that may actually be present. The
ability to produce this "biomass" is
often referred to as the "productivity"
of a body of water. This is neither good
nor bad per se. A water of low pro-
ductivity is a "poor" water biologically,
and also a relatively "pure" or "clean"
water, hence desirable as a water supply
or a bathing beach. A productive water
on the other hand may be a nuisance to
man or highly desirable. It is a nuisance
if foul odors and/or weed-chocked
waterways result, it is desirable if
bumper crops of bass, catfish, or
oysters are produced.
1-11
-------
The Aquatic Environment
i
REFERENCES
1 Clarke, G. L. Elements of Ecology.
John Wiley & Sons, New York. 1954.
2 Cooke, W.B. Trickling Filter Ecology.
Ecology 40(2) 273-291. 1959.
3 Hanson, E. D. Animal Diversity.
Prentice-Hall, Inc., New Jersey. 1964.
4 Hedgpeth, J.W. Aspects of the Estuarine
Ecosystem. Amer. Fish. Soc., Spec.
Publ. No. 3. 1966.
5 Odum, E.P. Fundamentals of Ecology.
W.B. Saunders Company,
Philadelphia and London. 1959.
6 Patten, B.C. Systems Ecology.
Bio-Science. 16(9). 1966.
1-12
-------
THE AQUATIC ENVIRONMENT
Part 3. The Freshwater Environment
I INTRODUCTION
The freshwater environment as considered
herein refers to those Inland waters not
detectably diluted by ocean waters, although
the lower portions of rivers are subject to
certain tidal flow effects.
Certain atypical inland waters such as saline
or alkaline lakes, springs, etc., are not
treated, as the main objective is typical
inland water.
All waters have certain basic biological cycles
and types of interactions most of which have
already been presented. Hence this outline
will concentrate on aspects essentially
peculiar to fresh inland waters.
II PRESENT WATER QUA UTY AS A
FUNCTION OF THE EVOLUTION OF
FRESH WATERS
A The history of a body of water determines
its present condition. Natural waters have
evolved in the course of geologic time
into what we know today.
B Streams
In the course of their evolution, streams
in general pass through four general
stages of development which may be
called birth, youth, maturity, and old
age.
1 Establishment or birth. In an extant
stream, this might be a "dry run" or
headwater stream-bed, before it had
eroded down to the level of ground
water.
2 Youthful streams; when the stream-
bed is eroded below the ground water
level, spring water enters and the
stream becomes permanent.
3 Mature streams; have wide valleys,
a developed flood plain, deeper,
more turbid, and usually warmer
water, sand, mud, silt, or clay
bottom materials which shift with
increase in flow.
4 In old age, streams have approached
geologic base level. During flood
stage they scour their beds and deposit
materials on the flood plain which
may be very broad and flat. During
normal flow the channel is refilled
and many shifting bars are developed.
(Under the influence of man this
pattern may be broken up, or
temporarily interrupted. Thus an
essentially "youthful" stream might
take on some of the characteristics
of a "mature" stream following soil
erosion, organic enrichment, and
increased surface runoff. Correction
of these conditions might likewise be
followed by at least a partial reversion
to the "original" condition).
C Lakes and Reservoirs
Geological factors which significantly
affect the nature of either a stream or
lake include the following
1 The geographical location of the
drainage basin or watershed.
2 The size and shape of the drainage
basin.
3 The general topography, l. e.,
mountainous or plains.
4 The character of the bedrocks and
soils.
5 The character, amount, annual
distribution, and rate of precipitation.
BI.21b.2.70
1-13
-------
The Aquatic Environment
6 The natural vegetative cover of the
land is of course responsible to many
of the above factors and is also
severely subject to the whims of
civilization. This is one of the major
factors determining runoff versus
soil absorption, etc.
D Lakes have a developmental history which
somewhat parallels that of streams.
b Filling with detritus eroded from
the shores or brought in by
tributary streams.
c Filling by the accumulation of the
remains of vegetable materials
growing in the lake itself.
(Often two or three processes may
act concurrently)
1 The method of formation greatly
influences the character and sub-
sequent history of lakes.
2 Maturing or natural eutrophication of
lakes.
a If not already present shoal areas
are developed through erosion of
the shore by wave action and
undertow.
b Currents produce bars across bays
and thus cut off irregular areas.
c Silt brought in by tributary streams
settles out in the quiet lake water,
d Rooted aquatic plants grow on
shoals and bars, and in doing so
cut off bays and contribute to the
filling of the lake.
e Dissolved carbonates and other
materials are precipitated m the
deeper portions of the lake in part
through the action of plants.
f When filling is well advanced,
mats of sphagnum moss may extend
outward from the shore. These
mats are followed by sedges and
grasses which finally convert the
lake into a marsh.
3 Extinction of lakes. After lakes reach
maturity, their progress toward
filling up is accelerated. They become
extinct through
a The downcutting of the outlet.
IU PRODUCTIVITY IN FRESH WATERS
A Fresh waters in general and under
natural conditions by definition have a
lesser supply of dissolved substances
than marine waters, and thus a lesser
basic potential for the growth of aquatic
organisms. By the same token, they
may be said to be more sensitive to the
addition of extraneous materials
(pollutants, nutrients, etc. ) The
following notes are directed toward
natural geological and other environ-
mental factors as they affect the
productivity of fresh waters.
B Factors Affecting Stream Productivity
(See Table 1)
TABLE 1
EFFECT OF SUBSTRATE ON STREAM
PRODUCTIVITY*
(The productivity of sand bottoms is
taken as 1)
Bottom Material
Relative Productivity
Sand
1
Marl
6
Fine Gravel
9
Gravel and silt
14
Coarse gravel
32
Moss on fine gravel
89
Fissidens (moss) on coarse gravel
111
Ranunculus (water buttercup)
194
Watercress
301
Anachans (waterweed)
452
^Selected from Tarzwell 1937
To be productive of aquatic life, a
stream must provide adequate nutrients,
light, a suitable temperature, and time
for growth to take place.
1-14
-------
The Aquatic Environment
1 Youthful streams, especially on rock
or sand substrates are low in essential
nutrients. Temperatures in moun-
tainous regions are usually low, and
due to the steep gradient, time for
growth is short. Although ample
light is available, growth of true
plankton is thus greatly limited.
2 As the stream flows toward a more
"mature" condition, nutrients tend to
accumulate, and gradient diminishes
and so time of flow increases, tem-
perature tends to increase, and
plankton flourish.
Should a heavy load of inert silt
develop on the other hand, the
turbidity would reduce the light
penetration and consequently the
general plankton production would
dimmish.
3 As the stream approaches base level
(old age) and the time available for
plankton growth increases, the
balance between turbidity, nutrient
levels, and temperature and other
seasonal conditions, determines the
overall productivity.
C Factors Affecting the Productivity of
Lakes
1 The size, shape, and depth of the lake
basin. Shallow water is more pro-
ductive than deeper water since more
light will reach the bottom to stimulate
rooted plant growth. Asa corollary,
lakes with more shoreline, having
more shallow water, are in general
more productive. Broad shallow lakes
and reservoirs have the greatest
production potential (and hence should
be avoided for water supplies).
2 Hard waters are generally more
productive than soft waters as there
are more plant nutrient minerals
available. This is often greatly in-
fluenced by the character of the soil
and rocks in the watershed and the
quality and quantity of ground water
entering the lake. In general, pH
ranges of 6.8 to 8.2 appear to be
most productive.
TABLE 2
EFFECT OF SUBSTRATE
ON LAKE PRODUCTIVITY *
(The productivity of sand bottoms is taken as 1)
Bottom Material
Relative Productivity
Sand
1
Pebbles
4
Clay
8
Flat rubble
9
Block rubble
11
Shelving rock
77
"¦Selected from Tarzwell 1937
3 Turbidity reduces productivity as
light penetration is reduced.
4 The presence or absence of thermal
stratification with its semi-annual
turnovers affects productivity by
distributing nutrients throughout the
water mass.
5 Climate, temperature, prevalence of
ice and snow, are also of course
important.
D Factors Affecting the Productivity of
Reservoirs
1 The productivity of reservoirs is
governed by much the same principles
as that of lakes, with the difference
that the water level is much more
under the control of man. Fluctuations
in water level can be used to de-
liberately increase or decrease
productivity This can be
demonstrated by a comparison of
the TVA reservoirs which practice
a summer drawdown with some of
those in the west where a winter
drawdown is the rule.
2 The level at which water is removed
from a reservoir is important to the
productivity of the stream below
1-15
-------
The Aquatic Environment
The hypolimnion may be anaerobic
while the epilimnion is aerobic, for
example, or the epilimnion is poor in
nutrients while the hypolimnion is
relatively rich.
3 Reservoir discharges also profoundly
affect the DO, temperature, and
turbidity in the stream below a dam.
Too much fluctuation in flow may
permit sections of the stream to dry,
or provide inadequate dilution for
toxic waste.
VII CLASSIFICATION OF LAKES AND
RESERVOIRS
A The productivity of lakes and impound-
ments is such a conspicuous feature that
it is often used as a convenient means of
classification.
1 Oligotrophic lakes are the younger,
less productive lakes, which are deep,
have clear water, and usually support
Salmonoid fishes in their deeper waters.
2 Eutrophic lakes are more mature,
more turbid, and richer. They are
usually shallower. They are richer
in dissolved solids, N, P, and Ca are
abundant Plankton is abundant and
there is often a rich bottom fauna.
3 Dystrophic lakes, such as bog lakes,
are low in pH, water yellow to brown,
dissolved solids, N, P, and Ca scanty
but humic materials abundant, bottom
fauna and plankton poor, and fish
species are limited.
B Reservoirs may also be classified as
storage and run of the river.
1 Storage reservoirs have a large
volume in relation to their inflow.
2 Run of the river reservoirs have a
large flow-through in relation to their
storage value.
C According to location, lakes and
reservoirs may be classified as polar,
temperate, or tropical. Differences in
climatic and geographic conditions
result in differences in their biology.
VIII SUMMARY
A A body of water such as a lake, stream,
or estuary represents an intricately
balanced system in a state of dynamic
equilibrium. Modification imposed at
one point in the system automatically
results in compensatory adjustments at
associated points.
B The more thorough our knowledge of the
entire system, the better we can judge
where to impose control measures to
achieve a desired result.
REFERENCES
1 Chamberlin, Thomas C. and Salisburg,
Rollin P. Geological Processes
and Their Results. Geology 1:
pp. l-xix, and 1-654. Henry Holt
and Company. New York. 1904,
2 Frey, David G. Limnology in North
America. Univ. Wise. Press. 1963.
3 Hutcheson, George E. A Treatise on
Limnology Vol. I Geography,
Physics and Chemistry. 1957.
Vol II. Introduction to Lake
Biology and the Limnoplankton.
1115 pp. 1967. John Wiley Co.
4 Ruttner, Franz. Fundamentals of
Limnology. University of Toronto
Press. pp. 1-242. 1953.
5 Tarzwell, Clarence M. Experimental
Evidence on the Value of Trout 1937
Stream Improvement in Michigan.
American Fisheries Society Trans.
66:177-187. 1936.
1-16
-------
The Aquatic Environment
6 U.S. Dept. of Health, Education, and
Welfare. Public Health Service.
Algae and Metropolitan Wastes.
Transactions of a seminar held
April 27-29, 1960 at the Robert A.
Taft Sanitary Engineering Center.
Cincinnati, Ohio. No. SECTRW61-3.
7 Ward and Whipple. Fresh Water
Biology. (Introduction). John
Wiley Company. 1918.
This outline was prepared by H. W. Jackson,
Chief Biologist, National Training Center,
FWPCA, Cincinnati, OH 45226.
1-17
-------
THE AQUATIC ENVIRONMENT
Part 4. The Marine Environment and its
I INTRODUCTION
A The marine environment is arbitrarily
defined as the water mass extending
beyond the continental land masses,
including the plants and animals harbored
within. This water mass is large and
deep, covering about 70 percent of the
earth's surface and being as deep as
7 miles. The salt content averages
about 35 parts per thousand. Life extends
to all depths.
B The general nature of the water cycle on
earth is well known. Because the rel-
atively large surface area of the earth
is covered with water, roughly 70 percent
of the earth's rainfall is on the seas.
(Figure 1)
70%
SKA SURFACE
Flgim 1. THE HATBt CTCU
Since roughly one third of the earth's
rain which falls on the land is again
recycled through the stratosphere
(see Figure 1 again), the total amount
of water washing over the earth's surface
is significantly greater than one third of
the total world rainfall. It is thus not
surprising to note that the rivers which
finally empty into the sea carry a con-
siderable burden of dissolved and
suspended solids picked up from the land.
This is the substance of geological
erosion.(Table 1)
Role in the Total Aquatic Environment
TABLE 1
PERCENTAGE COMPOSITION OF THE MAJOR IONS
OF TWO STREAMS AND SEA WATER
(Data from Clark, F W . 1924. "The Composition of River
and Lake Waters of the United States". U S. Geol Surv ,
Prof Paper No 135. Harvey, H W , 1957, "The Chemistry
and Fertility of Sea Waters", Cambridge University Press,
Cambridge)
Ion
Delaware River
at
Lambertville, N.J
Aio Grande
at
Laredo, Texas
Sea Water
Na
6 70
14 78
30 4
K
1 46
85
1 1
Ca
17 49
13 73
1 16
Mg
4 81
3 03
3 7
CI
4 23
21 65
55 2
504
17 49
30 10
7 7
co3
32 95
11 55
t-KCOj 0 35
C For this presentation, the marine
environment will be (1) described using
an ecological approach, (2) characterized
ecologically by comparing it with fresh-
water and estuarine environments, and
(3) considered as a functional ecological
system (ecosystem).
II FRESHWATER, ESTUARINE, AND
MARINE ENVIRONMENTS
Distinct differences are found in physical,
chemical, and biotic factors in going from
a freshwater to an oceanic environment.
In general, environmental factors are more
constant in freshwater (river) and oceanic
environments when compared to the highly
variable and harsh environments of estuarine
and coastal waters,
A Physical and Chemical Factors
(Figure 2)
1 Rivers
2 Estuary and coastal waters
3 Oceans
BI.2lb. 2. 70
1-19
-------
The Aquatic Environment
Degree of instability
Av iil-
afrility
of
nitrients
-degree)
Type of environment
and general direction
of water movement
Salinity
Temperature
Water
elevation
V ertical
strati-
fication
Turbidity
Riverine / J
1
1
-
-
-
/§mk
(|P
"""
mum
Vmm
¦
¦
-
¦
¦
I
Figure2 . RELATIVE VALUES OF VARIOUS PHYSIC iL AND CHEMICAL FACTORS
FOR RIVER, ESTUARINE, AND OCEANIC ENVIRONMENTS
B Biotic Factors
1 A complex of physical and chemical
factors determine the biotic composi-
tion of an environment. In general,
the number of species in a highly
variable environment tends to be less
than the number in a more stable
environment (Hedgpeth, 1966).
2 The dominant animal species (in
terms of total biomass) which occur
in estuaries are often transient,
spending only a part of their lives in
the estuaries. This results in better
utilization of a rich environment.
C Zoros of the Sea
Th'- nearshore environment is often
classified in relation to tide level and
water depth. The nearshore and oceanic
regions together are often classified in
relation to light penetration and water
depth.
1 Neritic - Relatively shallow-water
zone which extends from the high-
tide mark to the edge of the
continental shelf. (Figure 3)
i 1-20
-------
The Aquatic Environment
Benthal
Pelagial
_ Neritic
Region
Illuminated —
tjr-±
0
DO
01
tc
¦ o -
c
n
u
w
O
Dark _
>m
200
400
-J 600
Primary subdivisions of the marine habitat.
Figure 3.
a Stability of physical factors is
intermediate between estuarine
and oceanic environments.
b Phytoplankters are the dominant
producers but in some locations
attached algae are also important
as producers.
c The animal consumers are
zooplankton, nekton, and benthic
forms.
Oceanic - The region of the ocean
beyond the continental shelf. Divided
into three parts, all relatively
poorly populated compared to the
neritic zone.
Euphotic zone - Waters into which
sunlight penetrates (often to the
bottom in the neritic zone). The
zone of basic productivity. Often
extends to 600 feet below the
surface.
1) Physical factors fluctuate
less than in the neritic zone.
2) Producers are the phyto-
plankton and consumers are
the zooplankton and nekton.
b Bathyal zone - From the bottom
of the euphotic zone to about
6, 000 feet.
1) Physical factors relatively
constant but light is absent.
2) Producers are absent and
consumers are scarce.
c Abyssal zone - All the sea below
the bathyal zone.
1) Physical factors more con-
stant than in bathyal zone.
2) Producers absent and
consumers not as abundant
as in the bathyal zone.
1-21
-------
The Aquatic Environment
m SEA WATER AND THE BODY FLUIDS
A Sea water is a most suitable environment
for living cells, because it contains all
of the chemical elements essential to the
growth and maintenance of plants and
animals. The ratio and often the con-
centration of the major salts of sea water
are strikingly similar in the cytoplasma
and body fluids of marine organisms.
This similarity is also evident, although
modified somewhat in the body fluids of
both fresh water and terrestrial animals.
For example, sea water may be used in
emergencies as a substitute for blood
plasma in man.
B Since marine organisms have an internal
salt content similar to that of their
surrounding medium (isotonic condition)
osmoregulation poses no problem. On the
other hand, fresh water organisms are
hypertonic (osmotic pressure of body
fluids is higher than that of the surround-
ing water). Hence, fresh water animals
must constantly expend more energy to
keep water out (i.e., high osmotic
pressure fluids contain more salts, the
action being then to dilute this concen-
tration with more water).
1 Generally, marine invertebrates are
narrowly poikilosmotic, i.e., the salt
concentration of the body fluids changes
with that of the external medium. This
has special significance in estuarine
situations where salt concentrations
of the water often vary considerably
in short periods of time.
2 Marine bony fish (teleosts) have lower
salt content internally than externally
(hypotonic). In order to prevent
dehydration, water is ingested and salts
are excreted through special cells in
the gills.
IV FACTORS AFFECTING THE DISTRI-
BUTION OF MARINE ORGANISMS
A Salinity - The concentration of salts is
not the same everywhere in the sea, in
the open ocean salinity is much less
variable than in the ever changing
estuary or coastal water. Organisms
have different tolerances to salinity
which limit their distribution. The
distributions may be in large water
masses, such as the Gulf Stream,
Sargasso Sea, etc., or in bays and
estuaries.
1 In general, animals in the estuarine
environment are able to withstand
large and rapid changes in salinity
and temperature. These animals are
classified as:
a Euryhaline ("eury" meaning wide) -
wide tolerance to salinity changes.
EURYHALINE
Fresh Water
Stenohaline
Marine
Stenohaline
Salinity
0
ca. 35
Figure 4. Salinity Tolerance of Organisms
b Eurythermal - wide tolerance to
temperature changes.
1-22
-------
The Aquatic Environment
SNAILS
qjr
"r>3~Ci,V a .'
^ -0 J.
rs*-"
i,
' •/ ^ ^, r* ^
™o&0 0<
f'-- ® @
© ®
V© a
re % ®® I
- tV'J ,v a ©
fe.
'}V)|?tS r-r/'t^V ---
Pa': ? v^;
«aaa»
/>
r.
^ u' , 'VL' • S
Figure 5
Zonation of plants, snails, and barnacles on a rocky shore. While
this diagram is based on the situation on the southwest coast of
England, the general idea of zonation may be applied to any temper-
ate rocky ocean shore, though the species will differ. The gray
zone consists largely of lichens. At the left is the zonation of rocks
with exposure too extreme to support algae, at the right, on a less
exposed situation, the animals are mostly obscured by the algae.
Figures at the right hand margin refer to the percent of time that
the zone is exposed to the air, i.e., the time that the tide is out.
Three major zones can be recognized: the Littorina zone (above the
gray zone), the Balanoid zone (between the gray zone and the
lamina nag); and the Laminaria zone. a. Pelvetia canaliculata,
b. Fucus spiralis, c. Ascophyllum nodosum, d. Fucus serratus,
e. Laminaria digitata. (Based on Stephenson)
1-23
-------
The Aquatic Environment
2 In general, animals in river and
oceanic environments cannot withstand
large and rapid changes in salinity and
temperature. These animals are
classified as:
a Stenohaline ("steno" meaning narrow) -
narrow tolerance to salinity changes.
b Stenothernal - narrow tolerance to
temperature changes.
3 Among euryhaline animals, those living
in lowered salinities often have a
smaller maximum size than those of
the same species living in more saline
waters. For example, the lamprey
(Petromyzon marinus) attains a length
of 30 - 36 in the sea, while in the
Great Lakes the length is 18 - 24".
4 Usually the larvae of marine organisms
are more sensitive to changes in salinity
than are the adults. This character-
istic limits both the distribution and
size of populations.
B Tides
Tidal fluctuation is a phenomenon unique
to the seas (with minor exceptions). It is
a twice daily rise and fall in the sea level
caused by the complicated interaction of
many factors including sun, moon, and the
daily rotation of the earth. Tidal heights
vary from day to day and place to place,
and are often accentuated by local
meteorological conditions. The rise and
fall may range from a few inches or less
to fifty feet or more.
V FACTORS AFFECTING THE
PRODUCTIVITY OF THE MARINE
ENVIRONMENT
The sea is in continuous circulation. With-
out circulation, nutrients of the ocean would
eventually become a part of the bottom and
biomass production would cease. Generally,
in all oceans there exists a warm surface
layer which overlies the colder water and
forms a two-layer system of persistent
stability. Nutrient concentration is usually
greatest in the lower zone. Wherever a
mixing or disturbance of these two layers
occurs, biomass production is greatest.
Factors causing this breakup are, therefore,
of utmost importance concerning productivity.
ACKNOWLEDGEMENT:
This outline contains selected material
from other outlines prepared by C.M.
Tarzwell, Charles L. Brown, Jr.,
C.G. Gunnerson, W. Lee Trent, W.B.
Cooke, B. H. Ketchum, J. K. McNulty,
J. L. Taylor, R. M. Sinclair, and others.
REFERENCES
1 Harvey, H. W. The Chemistry and
Fertility of Sea Water (2nd Ed. ).
Cambridge Univ. Press, New York.
234 pp. 1957.
2 Hedgpeth, J.W. (Ed.). Treatise on
Marine Ecology and Paleoecology.
Vol. I. Ecology Mem. 67 Geol.
Soc. Amer., New York. 1296 pp.
1957.
3 Hill, M.N. (Ed.). The Sea. Vol. II.
The Composition of Sea Water
Comparative and Descriptive
Oceanography. Interscience Pubis.
John Wiley & Sons, New York.
554 pp. 1963.
4 Moore, H. B. Marine Ecology. John
Wiley & Sons, Inc., New York.
493 pp. 1958.
5 Reid, G. K. Ecology of Inland Waters
and Estuaries. Reinhold Publ.
Corp. New York. 375 pp. 1961.
6 Sverdrup, Johnson, and Fleming.
The Oceans. Prentice-Hall, Inc.,
New York. 1087 pp. 1942.
This outline was prepared by H. W. Jackson,
Chief Biologist, National Training Center,
FWQA, Cincinnati, OH 45226.
1-24
-------
WATER QUALITY CRITERIA FOR
PUBLIC WATER SUPPLIES
I SUPPLY AND DEMAND
A Ideally, public water should be available
in ample quantity and in undefiled quality
to satisfy all potential users, whether for
domestic, industrial, recreational, or
irrigation purposes.
B Realistically, nature and man's endeavors
are not compatible with such a goal.
1 Climate severely limits the amount of
water available in many areas.
2 When man uses water, he imparts
undesirable constituents to it before
returning it to the natural environment.
C In the early history of our country, and
even for a good part of this century, many
municipalities could withdraw water for
public consumption with no treatment,
except possibly chlorination.
D Today, virtually every community has a
considerable capital investment in water
treatment facilities.
II WATER QUALITY AND WASTE
TREATMENT
A The cost of treating water for public use
is directly related to the quality of treat-
ment given our wastewater.
One cycle of municipal use (as measured
by the difference in tap water and treat-
ment plant effluent qualities) increases
organic and mineral concentrations
substantially. See Table 1.
B In general, wastewater treatment has not
kept pace with expanding population.
1 The self-purifying capacity of our rivers
and lakes has been exceeded.
2 Many exotic and harmful compounds, a
product of our scientific age, are not
removed either by waste or water
treatment.
3 As late as 1962, only 30% of our waste-
water received secondary treatment.
Only 56% received any kind of treatment
(see Tables 2 and 3 below).
4 As an illustration of how the burden
has been placed on the rivers, there
currently are still no secondary treat-
ment plants on the Ohio River This
situation, fortunately, will end in the
early 70's.
5 The breakdown of the Nation's waste
treatment facilities is given in Table 4.
Trickling filters far outnumber activated
sludge plants.
Ill WATER TREATMENT TECHNOLOGY
A The conventional water treatment plant
employs techniques which primarily clarify
the water and render it hygenically safe.
Depending on the source, it may also be
necessary to:
1 Soften the water by adding lime and
sodium carbonate.
2 Employ activated carbon to improve
taste and odor.
B The individual treatment units generally
consist of a flash mixing chamber followed
in sequence by a flocculation basin,
sedimentation tank, rapid sand filtration
system, and a chlorine contact chamber.
Prechlorination also is sometimes practiced
A typical plant is pictured schematically in
Figure 1.
C Coagulants utilized most commonly are
alum or various iron compounds. The
effectiveness of the coagulation step is
highly dependent on pH Small doses of
polymers will aid coagulation, but very
few polymers have been approved for use
in water treatment.
D Detention times and/ or hydraulic loading
rates for the various units range as follows-
1 Flash mix - 10 to 15 sec.
2 Flocculation - 30 to 60 mm. (longer for
lime-soda softening),
3 Sedimentation - 2 to 6 hours with
preference for smaller period. Overflow
rates vary from 500 to 1,500 gal/sq ft/day
4 Rapid sand filtration - 2 to 3 gal/sq ft/min
with suspended solids of applied water no
more than 10 mg/1, preferably 5 mg/1.
W.Q. sto. 9. 7. 69
2-1
-------
Water Quality Criteria for Public Water Supplies
TABLB 1. -Water Quality Depreciation by One Cycle of Municipal Use
Tnt
Inrrrruetifji in mtt/l
Inrmnrnu in !b/da> /I 000 populitiita
IUitn\ i»
I >»> ton
1Intuition
Is-bnnoo
Lit clanrl
A% erAffo
liatAvim
lfciyton
Hamilton
I* tmrmfl
Lo*
Airrwto
COD—linfiltrrcd
III 1
1M
lb-i
84
141
14 <
05
207
188
98
no
140
C()|)—filtered
120
108
90
70
87
05
70
1 17
104
82
08
92
CJOl)—fil tired, corrected for CI"
112
08
70
40
70
82
05
124
'11
54
59
79
Xnioinr 2
4 0
00
7 1
5 '>
n l
7 1
54
70
6 9
H)
1 7
1 7
2 1
06
1 1
I 5
0 irhnhtdr itcs (glucose)
2(i
2 1
:> 0
00
1 5
2 4
1 5
2 7
5 8
1 1
1 2
2 5
Org iiiii nitrogen (N)
t 0
1 4
i 5
1 0
1 4
2 2
2 1
1 8
4 0
1 2
1 1
2 1
Nitrate (N)
\ 1
3 5
1 0*
7 7
40
I 5
1 8
4 5
1 2*
0 0
< 1
3 4
Nilrih (N)
0 58
0 10
0 04
0 25
0 55
0.«)
0 <4
(i n
0 05
029
0 4.1
0 25
\nunonu (N)
08
l(i s
2i 1
10 4
157
ir. i
i')
20 7
2.T 4
22 7
12 J
170
'1 olid nitrogen (Nr)
14 5
21 1
24 C
28 4
21 G
22 0
84
27 1
28 3
3.1 2
16 9
22 8
Tot.il ilk ilinit> (CaCO,)
152
1M>
217
40
41
122
88
201
25(1
47
32
124
C ill mm (C i*"1")
41
n
42
1
1
21
25
3'l
48
1
08
23
Magnesium (Nig**)
0
10
11
3
1
7
5
1 1
1 1
4
08
7
Pot i^Hium 6
22 7
21 7
183
21 5
298
Sulfate (SO.-)
JO
12
52
15
4(>
31
2.)
15
00
18
36
30
Chloride (CI")
40
51
40
102
4b
5b
23
05
4G
11<)
36
58
Residue 105cC
374
448
457
128
148
2!U
217
442
526
150
115
290
Residue b00®C
281
2J1
312
158
127
222
163
293
359
185
99
220
Loss on ignition
9J
117
145
30*'
21
69
54
149
167
35"
16
70
' Ij063
•• Gam
Note Lb X 0 454 = kg
Table 2
POPULATION WITH WASTE SYSTEMS FOR
YEAR 1962
Total population
Total sewered (63%)
Receive treatment
83% of sewered
56% of total
Table 3
TREATMENT CLASSIFICATION BY POPULATION
FOR YEAR 1962
Population
Type of
T reatment
% of
Treated
% of
Total
38 X 106
Primary-inter mediate
37
20
33 X 106
Activated sludge
32
18
23 X 106
Trickling filter
22
12
10 X 106
Other
9
C
2-2
186 X106
118 X106
104 X106
-------
Water Quality Criteria for Public Water Supplies
Table 4
TREATMENT CLASSIFICATION BY FACILITIES
FOR YEAR 1962
Number Type
11,655
Total
100
2, 277
Raw discharge
19. 5
9, 378
Treated discharge
80. 5
2, 794
Primary-intermediate
24. 0
6, 584
Secondary
56. 5
800
Activated sludge
7. 0
3, 506
(127c of secondary)
Trickling filters
CO
o
o
(53% of secondary)
1, 348
Stabilization ponds
12. 0
(20% of secondary)
5 Chlorination - at least 30 minute contact
before consumption.
E Solids - contact or upflow clarifiers are
being increasingly employed to combine
mixing, flocculation, and clarification in
one unit. Space is conserved and initial
cost is usually lower. Higher loading rates,
one hour detention and one gal/ sq. ft. /min.
overflow rate, are possible but rapid
variations in raw water turbidity have a
greater effect on product quality.
F Dissolved solids and trace elements and
compounds are little affected by any of the
above treatments. Calcium, magnesium,
and phosphorus can be removed by
precipitation and iron and manganese by
aeration but ion exchange and other tertiary
processes are needed to remove most other
ions.
IV STANDARDS FOR DRINKING WATER AND
PUBLIC WATER SUPPLIES
A The Public Health Service is charged with
setting standards for acceptable drinking
water for the Nation. The latest set of
standards were published in 1962. A
revised set of standards will probably be
forthcoming in the not-too-distant future.
B The Drinking Water Standards are con-
cerned with bacteriological quality, physical
and chemical characteristics, and
radioactivity.
C Sampling frequency is most critical in
determining bacteriological quality.
F igure 2 indicates the minimum number
of samples per month based on population
served recommended by Public Health
Service. They range from two samples
per month for 1, 000 people up to 500 per
month for 10, 000, 000 people.
D The Public Health Service 1962 Drinking
Water Standards are summarized in
Table 5.
E In 1968, the National Technical Advisory
Committee on Water Quality Criteria
formally reported to the Secretary of the
Interior on the aspects affecting water use
in this country. The five were recreation
and aesthetics, public water supplies,
fish and other aquatic life, agricultural
uses, and industrial water supplies.
F The Subcommittee for Public Water
Supplies developed raw water quality
criteria for public water supplies based
on reasonable treatment effort which
would yield saleable water meeting the
Drinking Water Standards.
1 Reasonable treatment is limited by the
subcommittee to coagulation and
flocculation with no more than 50 mg/1
alum or iron coagulants plus alkali
(but no coagulant aids or activated
carbon), sedimentation (six hours or
less), rapid sand filtration (three
gal/sq. ft/min. or less), and chlorination
(without regard to form or concentration
of residual).
2 Permissible criteria define acceptable
characteristics and concentrations of
substances in raw surface waters which
allow the production of a water meeting
the limits of the Public Health Service
Drinking Water Standards without
employing any more than the above
treatment.
2-3
-------
Water Quality Criteria for Public Water Supplies
Figure 1
-Posr-ch/orinatian for
dtst/vction of harmful
Organism t
Settling tostn
Oram
Clear • woter bosm
htsA myfer-^ ^Treated water
Rapid sand fitters
To htgh
_t servtce pumps
i .. Filtration plant, including coagulation, settling, filtration, postchlonnation and clear-water storage. Prechlorination.
La., addition of chlorine at the mixing bosiu, is also common practice.
Figure 2
DRINKING WATER STANDARDS, 1963
MINIMUM NUMBER OF SAMPUS PER MONTH
>
§
*
s
r
i
==t
10,000,000
2-4
-------
Water Quality Criteria for Public Water Supplies
Table 5
USPHS
Drinking Water Standards
1962
Constituent
Recommended
Limit
Maximum
Permissible
Limit
A. Bacteriological
Requirements vary depending on number of samples
collected per month and on type of test.
In general:
1. Positive fermentation based on MPN technique
a. 10 ml standard portions * 10% positive/mo.
b. 100 ml standard portions
2. Membrane filter
B. Physical
Turbidity (Jackson units)
Color (Color units platinum-
cobalt standard)
Threshold Odor Number
C, Chemical (mg/1)
Alkyl Benzene Sulfonate (ABS)
Arsenic (As)
Barium (Ba)
Cadmium (Cd)
Carbon Chloroform Extract (ccE)
Chloride (CI)
^60% positive/mo.
1/100 ml
15
3
0.5
0.01
+6
0.
250.
)
Chromium (Hexavalent) (Cr
Copper (Cu) 1.0
Cyanide (CN) 0.01
Fluoride (F) - temperature dependent 0.8 - 1.7
Iron (Fe) 0.3
Lead (Pb)
Nitrate (NO ) 45.0
Phenols 0.001
Selenium (Se)
Silver (Ag)
Sulfate (SO ) 250.0
Total Dissolved Solids (TDS) 500.0
Zinc (Zn) 5.0
D. Radioactive (pc/1)
Radium - 226
Strontium • 90
Gross beta
3
10
1,000
0.05
1.0
0.01
0.05
0.2
0.05
0.01
0.05
2-5
-------
Water Quality Criteria for Public Water Supplies
3 Desirable criteria define characteristics
and concentrations of a truly high quality
surface water supply which can be pro-
cessed with a greater safety factor by
the above treatment to meet the Standards.
4 Both sets of criteria are given in
Table 6. Where the term narrative
appears, the Subcommittee could not
arrive at a single numerical value
which would be applicable throughout
the country for all conditions.
G An examination of the Subcommittee's
recommendations reveals that they are
more encompassing than the Drinking
Water Standards. Undoubtedly, the next
issue of the Drinking Water Standards will
take cognizance of the Subcommittee's
Report.
V WATER CONSTITUENTS
The significance of constituents with defined
limits in the Drinking Water Standards and
the Subcommittee's report are discussed
briefly.
A Total Coliforms
1 Considered reliable indicators as to
possible presence of bacterial pathogens.
2 In general, all colxform organisms
exhibit similar survival and resistance
patterns.
3 Presence of any type of coliform
in treated water indicates inadequate
treatment or access of contamination
after treatment.
B Fecal Coliforms
1 Considered only in Subcommittee's
Report.
2 Indigenous to intestinal tract of
warmblooded animals.
3 Presence indicates recent fecal
pollution.
C Physical Characteristics
1 Turbidity, color, and odor limits
defined in PHS Standards.
2 Subcommittee's Report includes above
three plus temperature.
3 Physical characteristics related
to consumer acceptance rather than
safety of the water.
4 PHS limits are those concentrations
at which the physical characteristics
become objectionable to the senses.
5 Well operated treatment plants
should do much better.
D ABS
1 Anionic surfactant.
2 Above 1. 5 mg/1, taste, odor and
foaming complaints are common.
3 The recommended limit of 0. 5 mg/1
is 15, 000 times less than the sub-
acute toxic level to rats.
E Arsenic
1 Cumulative effect.
2 Absorbed into body tissues and fluids.
3 Suspected of being carcinogenic.
F Barium
1 Recognized as a general muscle
stimulant.
2 Capable of causing nerve block and
transient increases in blood pressure.
3 Acute toxicity associated with in-
gestion of barium salts such as
chloride due to irreversible changes
in tissues.
G Cadmium
1 Nonessential, nonbeneficial element
to biological processes of man.
2 Possesses high toxic potential.
3 Studies have shown accumulation in
soft tissues and marked anemia and
retarded growth in rats and adverse
renal arterial damage to man.
H Carbon Chloroform Extract
1 Indicates man-made or natural
organic pollutants not removed in
water treatment.
2 High sensitivity.
2-6
-------
Water Quality Criteria for Public Water Supplies
Report of Che
National Technical Advisory Conmltte«.
on Water Quality Criteria
to the Secretary of the Interior
TABLE 6. Surface Water Criteria (or Public Water Supplies
Parmlulbla Datlrabla
Comtltuant or characterHtlo criteria criteria Paragraph
Physical:
Color {color units) 75
Alkalinity Narrative Narrative 6
Ammonia 0 5 (as N) <0 01 7
Arsenic* 0 05 . Absent I_. .""8
Barium • 1 0 do 8
Boron * 1 0 do „ 9
Cadmium* .. 0 01 do I..18
Chloride * .250 . <25 8
Chromium,® hcxavalent 0 05 Absent 8
Copper* 10 Virtually absent 8
Dissolved oxygen >4 (monthly mean) Near saturation 10
>3 (individual sample)
Fluoride * Narrative Narrative 11
Hardness • do do 12
Iron (filterable) ... 0 3 ...Virtually absent 8
Lead * 0 05 Absent 8
Manganese* (filterable) 0 05 do 8
Nitrates plus nitrites 10 (as N) .Virtually absent 13
pH (range) G 0-8 5 Narrative 14
Phosphorus * Narrative do 15
Selenium" 0 01 Absent 8
Silver * 0 05 do 8
Sulfate • 250 <50 8
Total dissolved solids * 500 <200 16
(filterable residue)
Uranyl ion * 5 Absent 17
Zinc * 5 Virtually absent 8
Organic chemicals
Carbon chloroform extract * (CCE) 0 15 <0 04 18
Cyanide* 0 20 Absent 8
Methylene blue active substances * 0 5 Virtually absent 19
Oil and grease * Virtually absent .Absent 20
Pesticides
Aldrin * 0 017 do 21
Chlordane * 0 003 do 21
DDT * 0 042 do 21
Dieldrin * 0 017 do 21
Endrin * 0 001 do a.21
Heptachlor * 0 018 do 21
Hoptachlor epoxide* 0 018 do 21
Lindane* 0 056 do 21
Methoxychlor * 0 035 do 21
Organic phosphates plus -.0 1 ' do 21
carbamates *
Toxapliene ° 0 005 do 8
Herbicides
2,4 O plus 2,4,5 T, plus 2.4,5-TP * 0 1 do .21
Phenols* 0 001 do 8
Radioactivity (pe/i)
Gross beta * 1.000 <100 8
Radium 226 * ..3 <1 8
Strontium 90 * 10 <2 8
• Tha dafinad treatment process has little effect on this limit may be relaved if fecal coliform concentration does not
constituent exceed the specified limit
1 Microbiological limit* «re monthly Arithmetic Average* 9 As porathion in cliohnestorase irHbitlon It may be necei
based upon aQ adequate number of samples total coliform sary ro resort to even lower concentrations for some com
pound* or mixtures S«e par 21
2-7
-------
Water Quality Criteria for Public Water Supplies
3 Difficult to identify exact chemical and
toxicological nature of extracted
material.
I Chloride, Sulfate and Dissolved Solids
1 Importance associated with taste and
laxative properties.
2 Laxative effect of sulfates particularly
noticeable to newcomers and casual
users.
3 Experience has shown consumer shifts
to other supplies (such as bottled water)
when mineral concentrations become ob-
jectionable.
J Chromium
1 Tolerance when ingested not known
at present.
2 When inhaled, chromium is a known
carcinogemc agent for man.
3 Toxicity associated only with hexavalent
form.
4 Limit of Cr+® at 0. 05 mg/1 based on
analytical sensitivity.
K Copper
1 Essential in human metabolism.
2 Does impart some taste to water
above 1 mg/1.
3 Large doses may result in liver
damage.
4 Does not constitute a health hazard
at low levels.
L Cyanide
1 Standard based more on toxicity to fish
than to man.
2 Cyanide readily detoxified to thiocyanate
in the body.
3 Cyanide reduced to levels of about 0. 01
mg/1 with chlorination under alkaline
conditions.
M Fluoride
1 Valuable oral decay preventative in
children at proper doses.
2 Only harmful effect documented in
U.S A. is mottling of teeth at ex-
cessive concentrations.
N Iron and Manganese
1 Objectiorabl« because of astringent
taste and brownish color imparted
in excessive amounts.
2 No health considerations.
O Lead
1 Acutely toxic to humans.
2 Normal constituent in many food
sources and cigarettes.
3 Bacterial decomposition of organic
matter inhibited by concentrations
above 0. 1 mg/1.
P Nitrate and Nitrite
1 Nitrite can cause fatal poisoning due to
a condition known as methemoglobin-
emia.
2 With infants, nitrates can result in
the same situation because the low
acidity of the infant's stomach allows
certain bacteria to reduce nitrate
to nitrite.
3 The normal adult's stomach is too
acid for this to occur.
4 Other detrimental effects attributable
to nitrogen compounds (including
ammonia) are shown in Table 7.
5 The transformation of nitrogen
compounds when an inoculum is
aerated for several days is indicated
in Figure 3. The total amount of
nitrogen present is constant through-
out the transformation.
Q Phenols
1 Concentrations injurious to health
far greater than those which impart
unpleasant taste or affect fish.
R Selenium
1 Produces "alkali disease" in cattle.
2 Potential carcinogen to man.
2-8
-------
Figure 3
NITROGEN TRANSFORMATIONS
NITRATE-N
AMMONIA-N
NITRITE-N /
ORG ANIC -N
TIME, DAYS
p+
1
0
1
>TJ
c
cr
t=i
o
3
(O
«-»¦
o
W
C
¦a
¦a
a>
CO
-------
Water Qualqy Criteria for Public Water Supplies
TABLE 7. Importance of Nitrogen
NH3 in effluents can cause DO sag in
receiving water
NH3 is corrosive to copper fittings
1 NH3 requires 7 plus CI2 for breakpoint
NC>2 causes high CI2 demand
NHg influences CI2 contact time
Nitrogen compounds are nutrients
NO3 can be health hazard
S Silver
1 Sometimes added to water for dis-
infection.
2 Chief effect on body is cosmetic,
producing a blue-gray discoloration
of eyes, skin, and mucous membrane.
-T Z inc
1 Esthetic deterrent mainly due to acute,
but transitory, gastrointestinal irri-
tation.
U Radioactive Materials
1 Radium-226, Strontium-90, and Gross
beta are the three forms of radioactive
substances limited by PHS.
2 Limits based on recommendations of
Federal Radiation Council and approved
by the President.
V Additional Substances Considered by Sub-
committee Report, but not by PHS
Standards
1 Alkalinity
2 Ammonia
3 Boron
4 Dissolved Oxygen
5 Hardness
6 pH
7 Phosphorus
8 UranylIon
9 Oil and Grease
10 Pesticides
11 Herbicides
REFERENCES
1 Fair, G.W. and Geyer, J. C , Water
Supply and Wastewater Disposal.
John Wiley & Sons, NY, 1954
2 Public Health Service Drinking Water
Standards - 1962, PHS Publ. No. 956,
Washington, DC, 1962
3 Report of the Committee on Water
Quality Criteria, USDI,FWPCA,
Washington, DC, 1968
4 Sawyer, C N. , Chemistry for Sanitary
Engineers. McGraw-Hill, NY, 1960
5 Steele, E.W. , Water Supply and
Sewerage. McGraw-Hill, NY, 1960
This outline was prepared by R. C. Brenner,
Research Sanitary Engineer, Advanced
Waste Treatment Research Laboratory,
FWPCA, Cincinnati, OH 45226
2-10
-------
WASTEWATER TREATMENT" SCHEMATICS, FUNCTIONS, AND OPTIONS
I INTRODUCTION
A Wastewater treatment facilities are
engineered to recondition used water for
beneficial reuse. Traditionally these
facilities are designed to achieve in a
shorter time and smaller space a
similar degree of self purification that
may occur naturally under low load
conditions. Current thinking stresses
removal of many items that are
ineffectively removed by natural means.
B Increasing population concentration and
activity have caused increased stress on
treatment to meet Water Quality Standards
established by State Regional and Federal
Authority for the Nation's water resources.
These are dynamic standards subject to
adjustment with the changing needs of the
situation. This adjustment may be
expected to require higher and higher
treatment efficiency for more items.
C It is technically possible to recondition
used water for any reuse purpose.
Economics, public apathy, opinions,
operational competence enthusiasm and
enforcement commonly limit what will
be done in a given situation.
1 Certain items are much more difficult
to remove from used waters than others.
Special procedures are required to
supplement conventional treatment when
the hard-to-remove items are present
in significant amounts.
2 Strong wastes and moderate degrees of
treatment are much more economically
processed than when high degrees of
treatment are required. Costs of
upgrading treatment from 90 to 99%
removal may be much greater than that
to achieve the first 90% removal.
D The following schematics present an
overview of what may be fo ind in a wastewater
treatment plant and the functional purpose
of various items. These are not intended
to be complete or detailed. Other sources
of information provide details.
1 It is not possible to generalize what
shall be included in a given plant. The
State agency or agencies designated for
¦vater quality responsibility have primary
, i erest. Planning agencies. Construction
Grants, Professional A ssociations and
other groups have responsibility in the
use of public funds to meet the needs of
a given situation.
2 Plant design is the responsibility of a
professional consultant who is designated
to select the hardware and processes
to meet the needs of the situation as
defined by planning agencies.
Information gathered from the record,
current and projected activities of the
contributing population, nature of the
wastewater load, quality requirements
of the receiving water, availability of
water, site survey, treatment,
experience or studies all contribute to
design consideration.
3 The designed plant does not become a
functional reality until construction and
operation has been financed with people
competent to do the job. "Too little-
too-late" is a common problem in
treatment facilities because of losses
in transit and/ or the fact that needs
grow faster than available facilities
and manpower.
E Options in treatment technology must be
qualified. There are many alternate routes
for achieving a given treatment objective.
They are not equals with respect to cost
time, space, performance, operation,
opinion, etc.
1 Local opinion often favors one treatment
option over another that is considered
better in terms of cost efficiency and
dependability by another area and another
group.
2 Relative cost for land, hardware, and
operation are a large factor in process
selection.
3 Established practice, good or indifferent
tends to perpetuate itself. It is much
less effort to "sell" a well known process
than to design one precisely fitted to the
situation.
This outline was prepared by F. J. Ludzack,
Chemist, National Training Center, FWQA,
Cincinnati, OH 45226
SE. TT. eq. 5. 8. 70
3-1
-------
Wastewater Treatment: Schematics, Functions, and Options
The following schematics and options are for orientation purposes only. They are not intended
to illustrate all possible treatment schemes or any one treatment plant. Implications of
preference are not to be assumed by inclusion, omission or order of appearance.
19 illustrations to follow
WASTE WATER TREATMENT SCHEMATICS
PRE-TREATMENT
COARSE SCREENS GRIT CHAMBER
1 TO 5 IN SPACING
n ...ir
TO REMOVE
SAND
GRAVEL
HIGH DENSITY ITEMS
OTHER LARGE ITEMS
TO PROTECT SUBSEQUENT PROCESS
EQUIPMENT AND OPERATIONS
WASTEWATER TREATMENT OPTIONS
COARSE SCREENING
MANUALLY OR MECHANICALLY CLEANED FIXED OR
MOVING RAKES CLEANING
CYCLE ACTUATED BY TIME
OPERATOR
PRESSURE OR LEVEL CONTROL
SCREENINGS DISPOSAL
BURIAL
DRYING & INCINERATION
GRINDING 8. RETURN TO PROCESS WATER
i
TO REMOVE
ROCKS
ROOTS
RAGS
3-2
-------
Wastewater Treatment- Schematics, Functions, and Options
WASTEWATER TREATMENT OPTIONS
GRIT REMOVAL
LOCATION
COLLECTION SYSTEM
PLANT HEADWORKS
IN PROCESS
TYPES OF EQUIPMENT
LONG NARROW CHANNELS ( HORIZONTAL FLOW )
CIRCULAR FLOW BASINS ( CYCLONES )
UPFLOW TYPE BASINS
CENTRIFUGE EQUIPMENT
MANUAL OR MECHANICAL GRIT REMOVAL ( SOME TYPES )
HYDRAULIC GRIT WASHING
GRIT DISPOSAL
BURIAL
FILL ( OF WASHED MATERIAL )
WASTE WATER TREATMENT SCHEMATICS
PRE-TREATMENT
GRINDING (COMMINUTION )
AND/OR FINE SCREENS 0 04 TO I IN
SPACING
ROTATING
^ HAMMER
SCREEN
PRE AERATION OR OZONATION
AND/OR PRE CHLORINATION
IO
PRIMARY
IRtAJMENl
TO REDUCE SIZE OF MATERIAl
OR REMOVE
FIBER
STRINGS
CHUNKS
PLASTICS
TO FRESHEN THE WASTE WATER
DISINFECTION
OXIDATION
REDUCE ODOR
IMPROVE LATER TREATMENT
TO PROTECT SUBSEQUENT PROCESS
EQUIPMENT AND OPERATIONS
3-3
-------
Wastewater Treatment: Schematics, Functions, and Options
WASTEWATER TREATMENT OPTIONS
SIZE REDUCTION AND/OR FINE SCREENS
COMMINUTION
HAMMER MILLS VARIABLE CLEARANCE
FIXEO STATOR HIGH SPEED ROTOR SMALL CLEARENCE
HYDRAULIC SHEAR- ( CENTRIFUGAL PUMPS)
WITH OR WITHOUT OUTLE1 SCREENS
WITH OR WITHOUT TAKE OUT OF SELECTED MATERIALS
FINE SCREENS
VIBRA TING
SUBMERGED DRUM
HYDROSIEVE
MOVING BEL I - M ICROSC R EE N ING
SCREENINGS DISPOSAL
BURIAL
DRYING 4 (NCINERATION
GRINDING 5 RETURN TO PROCESS
TAKE OUT OF FIBROUS MATERIAL FAVORS LATER PROCESSING
WASTEWATER TREATMENT OPTIONS
PRE AERATION. PRE CHLORINATION , OZONATION
TREATMENT . FUNCTION
1 Aeiation [10-30 min ) a Satisfy immediate oxygen demand
b Decrease odor
c Improve later processing
2 Chlonnation Pa"'al d'smleclion ~ group I
3 ozonation Oecrease odor primarily + group 1
4 Pressurized Aeration & Release Floatation ot grease, oil. solids
May pressurize part or all of the flow
5 Additional Oegritting during retention
3-4
-------
Wastewater Treatment: Schematics. Functions, and Options
WASTEWATER TREATMENT SCHEMATICS
PRIMARY SEDIMENTATION
CLARIFIED WATER
COAOU1ATION MIXING
INLET
BAFFLE
SKIMMINGS
TAKEOUI
TO SECONDARY
TREATMENT
MflUINt
SCUM
BAFFLE
CONVEYORS FOR ^
SKIMMINGS « SLUDGE
tOllOS I flWOOl I TAKEOUT
SLUDGE COLLECTION HOPPER
fUMCIION: TO SEPERATE FLOATABLE OR SETTLEABLE
SOLIDS FROM THE CLARIFIED PRODUCT WATER
WASTEWATER TREATMENT OPTIONS
PRIMARY SEDIMENTATION
1 HAY BE OMITTED BEFORE CERTAIN SECONDARY PROCESS
2 RECTANGULAR TANKS
SLUDGE TAKEOUT AT INLET OR OUTLET END
VARIOUS LENGTH/WIDTH/DEPTH CONFIGURATIONS
3 CIRCULAR TANKS
CENTER FEED OR PERIPHERAL FEED
VARIOUS WEIR ARRANGEMENTS
4 SLUDGE COLLECTION
DRAG OR FLIGHT BOARDS ON LINKED CHAIN
SUCTION MECHANISM - FIXED OR MOVING
ROTATING BRIDGE - SUCTION OR DRAG
5 TUBE TYPE - MOSTLY FOR SEC CLARIFICATION
6 SLUDGE DRAW OFF
PISTON PUMPS
CENTRIFUGAL PUMPS
AIR LIFT OR PNEUMATIC EIECTORS
SCREW TYPE PUMPS
3-5
-------
Wastewater Treatment: Schematics. Functions, and Options
WASTEWATER TREATMENT SCHEMATICS
SECONDARY TREATMENT
INFLUENT
FROM PRIMARY
SEDIMENTATION
COAGULATION
(WIIH OR WITHOUT
CHEMICAL ADDITIVES)
MIXING
AERATION
SEPARATION
RECYCLE SLUDGE
CLARI-
FICATION
TO OlStMHCtlON
ADV IttAtMtNf
OISCHAROE
WASTE S1UDOI
TO FINAL TREATMENT
AND DISPOSAL
FUNCTION LIOUID TO SOLIDS TRANSFER
BIO AND/OR CHEMICAL FLOCCULAIION
PARTIAL OXIDATION
CONVERSION OF SOLUBLE & COLLOIDAL
SOLIDS TO SEPARABLE FORM
SEPARATION Of CLARIFIED
PRODUCT WATER FROM
SKIMMINGS OR SLUDGE
WASTEWATER TREATMENT OPTIONS
SECONDARY TREATMENT
1 ACTIVATED SLUDGE (FLUID SLIME SUSPENSION)
a HIGH RATE > I 0 lb COD/ lb MLVSS/DAY
b CONVENTIONAL 0 4 - I 0 lb. COD/MlVSS/DAY
c EXTENDED AERATION < 0 4 lb COD/lb MLVSS/DAY
d COMPLETE MIX OR PLUG FLOW
0 MECHANICAL, DIFFUSED AfR OR COMBINATION OXYGENATION
1 CONTACT, 7 STAGE, TAPERED AERATION, STEP FEED,
KRAUSE PROCESS, CHEMICAL COAGULATION. N2 OXID.-RIO
3-6
-------
Wastewater Treatment- Schematics, Functions, and Options
WASTEWATER TREATMENT OPTIONS
SECONDARY TREATMENT
TRICKLING FILTRATION (FIXED MEDIA SLIMES)
a HIGH RATE 25 - 300 lbs BOD5 /lOOOcu (t OF MEDIA
b LOW RATE 5-25 lbs BODS/1000 to It OF MEDIA
c RECIRCULATING (OF CLARIFIED EFFLUENT, SLUDGE, OR MIXTURES)
d SHALLOW OR DEEP BEDS
c ROCK, SLAG, OR MANUFACTURED MEDIA
I 2-STAGE, NATURAL OR FORCED DRAFT, COMBINED TRICKLING
FILTRATION AND ACTIVATED SLUDGE
WASTEWATER TREATMENT OPTIONS
SECONDARY TREATMENT
OXIDATION PONDS
A DEPTH SHALLOW | 1 5 FT ) DEEP | 5 25 FT )
B TIME
-= 3 DAYS PRIMARILY SEDIMENTATION
3 20 DAYS SUSPENDED SLIME GROWTH
=~ 20 DAYS GROWTH FLOCCULATION. DEPOSITION
C SINGLE OR MULTIPLE PONDS
SERIES OR PARALLEL OPERATION
D PRIMARILY AEROBIC, ANAEROBIC. FACULTATIVE
E NATURAL OR FORCED AERATION & MIXING
F RECIRCULATION (EFFLUENT, SOLIDS, OR MIXTURES ]
G LEVEL CONTROL | OVERFLOW, PERCOLATION, EVAPORATION ]
H CLARIFICATION INCIDENTAL OR SEPARATE
ENGINEERED OR NATURAL SOLIDS TAKEOUT
3-7
-------
Wastewater Treatment •^Schematics, Functions, and Options
WASTEWATER TREATMENT OPTIONS
PHYSICAL CHEMICAL TREATMENT
1 APPLICATIONS
A RAW WASTEWATER
B IN PROCESS SUPPLEMENTATION TO BIOL TREATMENT
C AFTER BIOLOGICAL TREATMENT
2 NATURE OF TREATMENT
A LIME COAGULATION
B ALUM OR IRON COAGULATION
C POLYMER COAGULATION
D AMMONIA STRIPPING
E CARBON ADSORPTION POWDER OR GRANULAR
F FILTRATION ( SAND, MIXED BED, SOIL MICROSTRAINING MOVING BED]
G ELECTROPHORESIS
H ION EXCHANGE
I DISTILLATION
J DISINFECTION
K CHEMICAL OXIDATION
WASTEWATER TREATMENT SCHEMATICS
TREATED LIQUID STREAM
coagulation
chemicals
influent
liom
secondary
tieatment
FUNCTION
clarification
11 It r at ion
CI2 detention
_i
sludge takeout 10
~Y~
chlonnation
to receiving
water 01
othei reuse
TD INCREASE P 0 SS IB IL11 IE S
FOR REMOVAL OF ITEMS
PASSING THROUGH
CONVEN110NAL
TREATMENT
TO PRODUCE A WATER
LOW IN DISSOLVED OR
SUSPENDED SOLIDS
IBIOLOGICAL OR OTHER|
TO DISINFECT
THE DISCHARGE
3-8
-------
Wastewater Treatment: Schematics, Functions, and Options
WASTEWATER TREATMENT
SLUDGE DEWATERING
SLUDGE CONDITIONING
CHEMICALS
CLOTH
IrrmjJ
FILTER
Qi
PROCESS
WATER
<- MIXER
SLUDGE
FROM
PRIMARY
SECONDARY
ADVANCED
TREATMENT
SOLIDS CONC 2 - 5 TIMES
EXAMPLE 1°/. TO 4% SOLIDS
FUNCTION
. TO DRYING
t DISPOSAL
L LIQUID RETURNED
TO PROCESS
SOLIDS CONC S TO 10 TIMES
EXAMPLE 4% - 25% SOLIDS
To reduce the water content of the sludge as much as
possible by the most economical and feasible route for
the situation
To reduce the amount of water to be evaporated
WASTEWATER TREATMENT OPTIONS
SLUDGE DEWATERING
1 LAND SPREADING (COVER CROP, TILLING, BURIAL)
2 SLUDGE DRYING BEDS
3 FILTRATION (VACUUM, VIBRA
4 INDUCED HEAT (SPRAY, ROTA
5 CENTRIFUGATION
6 FREEZING
7 CHEMICAL CONDITIONING
8 HIGH PRESSURE & TEMPERATURE DIGESTION
9 FLOTATION
10 SEDIMENTATION
TING SCREENS, SAND, ETC )
RY KILN, TRAY)
3-9
-------
Wastewater Treatment: Schematics, Functions, and Options
WASTE WATER TREATMENT SCHEMATICS
SLUDGE DRYING & DISPOSAL
r air
FUEL I'I
WASH WATER
OFF GASES
SLUDGE
DRIER INCINER
AFTER
BURNER
FROM
DEW ATERING
OPERATIONS
ROTATING ARMS
SLUDGE
FIXED PLATFORMS
ASH DUMP 0 Q
FUNCTION
DRIVE SHAFT |AIR
COOLED AIR INLETI
V
WASH WATER
' TAKE OFF TO
PROCESS
SIUDGE FOR DISPOSAL
To complete the drying operation and convert intermediate products
to their highest oxidation state
To stabilize off gases with respect to odor, oxidation state, and
suspended solids
WASTEWATER TREATMENT OPTIONS
SOLIDS DISPOSAL METHODS
1 LAND DISPOSAL FOR REUSE, CROPPING, SOIL
CONDITIONING, FOR ISOLATION,
SANITARY FILL
2 INCINERATION FOR CONVERSION TO INNOCUOUS
GASES & ASH AT THEIR HIGHEST
OXIDATION STATES
3 TRANSPORT TO REMOTE AREAS
4 SEA DISPOSAL PREFERABLY DEEP WATERS
5 RECOVERY FOR REUSE
6 UNDERGROUND INJECTION
3-10
-------
Wastewater Treatment Schematics, Functions, and Options
WASTEWATER TREATMENT OPTIONS
DISPOSAL ROUTES
1 RENOVATED WATER
RETURN FOR BENtriCIAL REUSE
2 GASES
a STABLE
b UNSTABLE
TOXIC
ODOROUS
3 SOLIDS
a INSOLUBLE INORGANIC
b SOLUBLE INORGANIC
c ORGANIC
RETURN TO THE ATMOSPHERE
OXIDIZE RECOVER STABILIZE CONVERT TO
NON POLLUTIONAL FORM BEFORE RETURN OF THE
ACCEPTABLE FRACTION TO THE ATMOSPHERE
RETURN TO THE LAND OR SEAS
RETURN TO SALINE WATERS ISOLATED SALINE
SUBSURFACE STRATA RECOVER FOR REUSE
STABILIZE CONVERT TO GASES ACCEPTABLE FOR
RETURN TO THE AIR AND SOLIDS ACCEPTABLE FOR
RETURN TO THE LAND ISOLATE SOLIDS WITH MINIMUM
WATER CONTACT
3-11
-------
WASTEWATER TREATMENT - THE RESULT OF NATURAL PHENOMENA
I INTRODUCTION
All sewage treatment is accomplished by
application of biological, physical, chemical
processes. These processes are natural
phenomena which have been in operation since
primeval time. Man has not always under-
stood these processes and in fact we may not
have a complete understanding of them at this
time; nevertheless, it is by means of these
phenomena that sewage treatment is possible.
D PHYSICAL PROCESSES
A Specific Density
The density of waste solids, coupled with
the law of gravity, provides a physical
phenomena resulting in removal of wastes.
Sedimentation has been observed by man
for thousands of years and a study of
geologic formations reveal that sedimentation
has been continuing for millions of years.
In nature, the pools in streams, lakes, and
estuaries provide the necessary conditions
of quiescence to allow gravity separation
of settleable solids.
In using the physical laws relating to
gravity and specific density, man has
used two processes
1 Sedimentation in tanks built to provide
quiescence, and
2 Centrifuge separation
B Particle Size Distribution
Screening sewage flows to remove large
particles is merely an application of size
selection. Screens abound in nature as
settled rock deposits which prevent move-
ment of twigs, sticks, leaves and other
solids. The earth itself acts as a fine
screen and filter, removing all water-
borne material except those that are
dissolved. In treatment plants, bar racks
and sand filters are applications of these
natural conditions.
C Reaeration
Few people have failed to take the time to
see a waterfall or to enjoy the scenic
beauty of a fast-flowing and turbulent
mountain stream. These are nature's
examples of reaeration facilities. In
addition to these dramatic aerators,
there is a constant exchange of molecules
of oxygen and other atmospheric gases
across the liquid-gas interface of rivers,
lakes, ponds, and oceans. The wind
provides mixing energy to carry the
dissolved gases to portions of the water
mass below the surface. Utilizing these
principles as treatment processes, man
injects air into the waste flow by use of
air under pressure; the making of water-
falls by pumping the liquid into the air
fountain-like; or, by creating an infinitely
large surface area with depth being
merely a thin film as the liquid trickles
downward over beds of rock.
Ill BIOLOGICA L PROCESSES
In the real world the aquatic community is
very complex, consisting of organisms of
every size from the virus to the fishes.
Each has a definite role in the community
and in a natural environment--one unaffected
by wastes from man's activities--there is a
very great variety of different kinds and
species. All are present in such numbers as
will maintain a balance with the food supply
available.
Action by bacteria in this community breaks
down complex organic matter to simpler
molecular forms. These become the basic
building blocks for new growth by other
microorganisms. These in turn are a food
source for yet other, more complex,
organisms. This activity of decomposition
and growth is a continuous one--such that
the process is cyclic.
SE.TT.4. 11.68
4-1
-------
Wastewater Treatment - The Result of Natural Phenomena
All the elemental components of organic
material--carbon, nitrogen, sulfur, etc.--
are cyclic. The carbon cycle (Figure 1) is
an example. It can be seen that once elements
making up organic matter, from any source,
enter the aquatic environment they will con-
tinue in the cycle indefinitely unless they are
removed as a "Harvest" as fish or other
product.
IV CHEMICAL PROCESSES
Chemical processes in the aquatic environ-
ment are intimately connected with biological
activity and proceed simultaneously with
photosynthesis, assimilation and decomposition.
In addition, the chemistry of water is a
function of the solubility and presence of
inorganic salts in the environment.
Radiant
Energy
Carbon
Dioxide
(CO )
.£?¦
Plant
Proteins
arbohydrat
and Fats
on
living or
game matt
and waste
Death
nima
Proteins,
arbohydrat
and Fats
Carbon Cycle
Figure 1
4-2
-------
Wastewater Treatment - The Result of Natural Phenomena
The salt content of the oceans, the Dead Sea,
the Salton Sea, and Great Lake are examples
which indicate that once inorganic salts enter
the aquatic environment they remain indefinitely
as an integral part. It is only by means of
evaporation that water high in inorganic salts
is returned, in the form of rain and snow, to
the fresh water state.
V LIMITATIONS OF NATURAL TREATMENT
A Although wastes discharged into the aquatic
environment enter the cycle previously
described, time is required to reach a new
balance during which time water quality
may be seriously impaired. In addition,
the new balance may not be a desirable one
as excessive nutrients may bring about
blooms of organisms causing nuisance
conditions and/or foul odors and tastes.
B It is axiomatic that elements of wastes
removed prior to discharge into the aquatic
environment do not enter these cycles and
therefore cannot cause adverse effects.
C A stream has capacity to accept organic
wastes and through natural processes to
self-purify; however, its capacity to
assimilate wastes without seriously
affecting water quality for other uses is
limited by such factors as stream flow,
reaeration rate, temperature, etc.
REFERENCES
1 Fair, G. M. and Geyer, J. C., Water
Supply and Waste-Water Disposal,
John Wiley & Sons, Inc., New York,
(1966).
2 McKinney, R.E., Microbiology for
Sanitary Engineers, McGraw-Hill
Book Company, New York, (1962).
3 Rich, L. G., Unit Processes of Sanitary
Engineering, John Wiley & Sons,
New York, (1963).
This outline was prepared by L. J. Nielson,
Sanitary Engineer, FWPCA Training
Activities, PNWL.
4-3
-------
UNIT OPERATIONS IN WASTF TIM A "I 1\11, \ I
I INTRODUCTION
A Definitions
1 Unit operation^ a particular kind of a
physical change that is repeatedly and
frequently used as a step in the process
for industrial chemicals and related
materials Examples include filtration,
evaporation, distillation, heat transfer,
fluid transfer, sedimentation and mixing
2 Unit process^ a particular kind of
chemical reaction and equipment to
which the same basic designs and
operation may be applied Oxidation,
coagulation, disinfection, hydrolysis
and chemical absorption are common
examples
3 Process - a series of actions or opera-
tions conducing to an end A continuing
operation or treatment consisting of a
combination of unit operations For
example, the activated sludge process
includes mixing, fluid and gas transfer
and clarification among unit operations,
oxidation, hydrolysis and coagulation
either biological or chemical among
unit processes.
(2)
4 Wastewater treatment any process
to which wastewater is subjected to
remove or alter its objectionable
components.
a Wastewater treatment may also be
defined as a series of unit operations
designed to produce a product "clean
water" from a raw material "waste
water. "
b Treatment is a means to renovate
used water to meet a specific
beneficial reuse requirement.
c Conventional treatment is commonly
classified by stage or degree of
treatment such as preliminary or
pretreatment, primary, secondary,
or advanced treatment Processes
such as activated sludge, trickling
filtration or oxidation pond treat-
ment are commonly used Each of
these can be more precisely
described and better understood
in terms of the unit operations
involved
PC WAS 4b. 11 70
d Unit operations for purposes of
this outline include both "unit
operations' (A 1) and "unit
processes" (A 2) to distinguish
unil process from the more
gene rail v applied term "process"
which may include manv unit opera-
tions or unit processes
B Increasing stress on environmental
quality means that wastewater treatment
must be upgraded Upgrading treatment
means removal of a larger fraction of
conventionally removed components and
removal of additional items presently not
significantly removed by conventional
treatment This also means treatment
of a larger fraction of collectable waste-
waters for a greater variety of used
water types and components for 24 hours
per day, 365 days per year
1 The unit operation concept tends to
focus attention upon the specific com-
ponents to be removed and upon
fundamental units most suitable for
that function The unit operation
approach offers a wider selection for
design purposes than that available
in empirical plant design The treat-
ment therefore may be more specific,
better tailored to the situation and show
a better cost/benefit ratio
2 Implementation of treatment operations
requires motivated and trained man-
power Personnel training along the
unit operations route shortens the time
and promotes better comprehension by
focusing upon the unit operations or
tasks most commonly used Rotation
among assignments is a smoother and
progression more likely because the
individual trained in unit operations
tends to recognize familiar unit opera-
tions in the new assignment his learning
requirements consist of the differences,
such as a different sequence of lamihar
tasks, a smaller number of new unit
operations, and different handling
techniques because of material or
situation. Learning is split into funda-
mental units Personal progress, |ob
satisfaction, and competence increase
with the recognition of proficiency of
the smaller "bits "
5-1
-------
Unit Operations in Waste Treatment
C This outline considers selected umU ^
operations of sanitary engineering
and processes based upon them Tables
presented later summarize interrelations
and the means whereby these are combined
into processes or stages of treatment.
1 Unit operations are the fundamental
"building blocks" of treatment
2 Unit operations are the alternate routes
to a given objective Solids-liquid
separations may be achieved by many
different operations, some are favored
in one situation, others limited by that
situation
D The following sections consider individual
unit operations and their characteristics
as guidelines for selection or design.
These notes are general in nature and
subject to the influence of waste charac-
teristics, local conditions, practice,
economics and water quality requirements
of the situation. Each unit operation is
characterized in terms of-
1 Favorable application factors
2 Limiting application factors that may
encourage selection of an alternate
operation for a particular situation
II PHYSICAL UNIT OPERATIONS -
SOLID-LIQUID SEPARATIONS
The separation of solids from liquid, or the
reverse, is of primary importance to
wastewater treatment. Various unit oper-
ations or adaptations of them to achieve this
objective may be used to remove objectionable
components, to protect process equipment, to
simplify subsequent operations, to increase
stability of process water, to make the water
more amenable for treatment or to complete
the process Separations may be a part of
pretreatment, an integral process step, or
a means of upgrading process effluents. No
single operation appears more frequently, in
more numerous adaptations, at more stages
in processing, and is more critical in product
water upgrading than solids-liquid separation.
A Cravity Sedimentation
1 Favorable aspects Thib unit operation
is by far ths least expensive and feasible
route for a large variety of separations
May be adapted for separation of a variety
of materials having a specific gravity
sufficiently different from that of water
and immiscible 111 it sucli as High
dsnsity sand, gia\rl or scale, moderate
density organic buspended materials,
low density floatable materials
Requires simple and generally available
equipment Operating variables are
known and generally controllable to
favor reliable treatment
2 Limitations- Adversely affected by
variations in wastewater characteristics
and flow. Requires a moderately large
capital, equipment and area investment
Sludge detention conducive to solids
liquefaction and feedback Affected by
short circuiting, turbulence, distribu-
tion, temperature or density changes
Relatively slow operation in most
situations
B Surface Filtration
1 Coarse or fine screens
a Favorable- Inexpensive simple
operation and equipment Reliable
removal of discrete solids larger
than the screen openings Equipment
available and operating practice known
Simplifies subsequent operations Low
area requirement
b Limitations: Susceptible to plugging,
large quantities of wet, difficult-to-
handle solids Variable loading may
result in operating and performance
problems associated with higher loads
2 Microscreens
a Favorable: Produces an effluent of
low suspended solids (<10 mg/1) and
low turbidity (2JTU) at low capital,
operating time and area cost at
rated loading Simple operating
requirements Equipment avail-
ability good
b Limitations Poor tolerance for high
suspended solids feeds (>50 mg'l)
Tends to plug filter surface Affected
by changes in waste characteristics
Solids breakthrough at excessive
loading
3 Diatomaceous earth filtration
a Favorable Produces a high quality
effluent low in suspended solids and
turbidity (0 1 to 1 0 JTU) Low area
requirement Pressure buildup
rather than solids breakthrough warn-
ing of overloads
5-2
L
-------
Unit Operations in Waste Treatment
b Limitations- High pressure drop
through the filter, rapidly increases
with solids loading. Tends to plug
Low output/ sq ft. / unit time with
high suspended solids feed
4 Vacuum filtration
a Favorable: Suitable for treatment
of a variety of solids-liquid
concentrates Large choice of
filter media including string, coil,
cloth (natural or synthetic) screens.
Versatile in adaptability for varying
conditions and loading. Low area
requirement High capacity per
unit area.
b Limitations Complex operation,
high maintenance cost. Usually
requires chemical coagulation or
coagulant aids. High capital and
operating cost Requires frequent
attention to maintain capacity during
varying load and sludge characteristics.
High cake moisture content produces
a poor quality filtrate.
C Bed Filtration
Many options are available such as type
of media (sand, coal, gravel, synthetics,
etc.) size of media (from fine sand to
rock or manufactured media) and flow
direction (up flow or down flow, com-
pressed or expanded bed) Fine media
and downflow operation may resemble
operational characteristics of surface
filtration. Coarse media, multi media,
expanded beds represent filtration in
depth. In some situations such as trickling
filtration, the process is largely a
biological phenomena rather than intrinsi-
cally filtration
1 Sand or single media filtration.
Characterized by a high rate of head
loss development with high solids
loading.
a Favorable High quality effluents
produced. Increased solids, oxygen
demand, and organism removals
specially with low application rates.
Beneficial for upgrading reasonably
good quality treated effluents
Dependable polishing step. Simple
operational control.
b Limitations: Large area requirement
Usually requires pretreatment for
removal of most of the solids High
head loss development specially for
high rate application Usually
an intermittent operation Low
capacity per unit time Media
replacement based upon incidence
of "balling," backwash losses,
deposition on the grains, and
nature of feed stock contamination
Possible odor development
Backwash water may be volumi-
nous and generally requires
retreatment.
2 Soil percolation
a Favorable- Generally a dependable
method of effluent disposal where
land is available Returns both
water and wastewater nutrients to
the food chain. Useful for land
reclaimation purposes. Requires
simple operation and low operational
cost. Versatile for use with a wide
variety of wastewater types.
b Limitations- Commonly limited with
respect to application rates Requires
a large land area for intermittent
operation. Capital cost primarily
related to land area requirements
Disinfection commonly required.
Good agricultural practice needed
to support good engineering A
cover crop, tilling and drainage
control generally required. Subject
to seasonal, soil, and topographical
factors. Odors and health hazards
tend to produce a poor public image
Ground or surface water hazard
potential.
3 Multi media filtration
The use of two or more filter media
in which both size and density are
variable makes it possible to distribute
trapped particulates in a wide zone
with respect to filter depth Usually
a larger sized lower density media
are placed over a fine high density
media Larger particulates are
trapped in the upper zone while the
fine media upgrade effluent clarity
Head loss development occurs more
gradually to permit longer runs of high
product quality as compared with
single media filtration
a Favorable Head loss distributed
throughout the bed, builds up more
slowly to permit higher rate and
volume application Dependable
high quality effluent production
Generally high capacity characteristics
5-3
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Unit Operations in Waste Treatment
Capable of being tailored to fit a
particular feed and effluent quality
requirement.
b Limitations: Design generally
requires more careful evaluation
of feed and product quality
requirements. Solids load and
nature are critical. Requires
more careful control during back-
washing to make it a more complex
operation than sand filtration.
Intermittent operation. Media and
equipment more expensive. Usually
requires pretreatment. Backwash
water requires retreatment--may
require more backwash water or
more time than for single media
filtration. Media replacement may
be higher.
D Pressure Floatation
1 The operation consists of aeration
of part or all of the liquid flow in a
covered tank to trap exhaust air and
provide a controlled pressure rise.
Under pressure more gas will dissolve
than can be retained at normal pressures
Discharge of the pressurized liquid to
the clarifying compartment permits
release of excess dissolved gas The
released gas tends to associate with
oil, scum and particulates to favor
separation from water as a floatable
concentrate. Variables include time
pressure, turbulence, air-liquid-solid
interface area and nature, and associa-
tion tendencies in both pressure and
clarifying compartments.
a Favorable
The floatation process is highly
versatile for separation of oils
emulsions or particulates It may
be used for thickening or clarifica-
tion with or without conditioning
chemicals such as surface active
materials, coagulants or other
separation aids. It is possible to
employ higher loading and higher
overflow rates than for sedimentation
A higher solids concentration factor
may be achieved More complete
clarification of hard-to-separate
materials is possible. Usually
requires less area per unit of
capacity
1) Activated sludge concentration
by floatation is becoming
increasingly popular because the
hydrated solids are amenable to
the floatation process to a greater
extent than for sedimentation
2) Oil and surface active agents
tend to be more completely
separated by floatation to pro-
duce a better clarified product
water.
b Limitations- Usually requires very
careful design and operation for a
specific situation. The complex
operation is sensitive to feed stock
variations. Generally more com-
plex equipment requiring closer
control More amenable to moder-
ately concentrated feeds. Thickening
operations may require duplicate
solids handling for removal of float-
able and settleable fractions The
subnatant zone commonly has a high
solids concentration requiring
retreatment Clarification commonly
is improved by increasing feed stock
concentration. More expensive in
capital and operating cost than
sedimentation
E Centrifugation
The centrifuge has a long history for
dependable separation of liquid-solid
suspensions according to specific gravity
differences Solid bowl, basket, or disc
type machines are available Horizontal
solid bowl units appear to have the greatest
potential in sanitary engineering Organic
sludge from water and grit from organic
sludge separations are attractive
Variables include feed rate, solids-liquid
characteristics, feed concentration,
temperature, chemical additives; machine
variables include bowl design, rotational
speed, contained volume, input, distribution
and takeout mechanisms
1 Favorable: Highly versatile, may be
designed for high sludge concentration
or high separation on a variety of feeds
High capacity-low area requirements
Low capital cost per unit of capacity
Capable of solids concentrations up to
30 to 35 percent with favorable loads
and operation, continuous performance
2 Limitations- High power requirements
(~0. 5 HP/gpm) Usually necessary to
make a choice between high solids con-
centration and high solids recovery--
unlikely to have both Reduced feed
5-4
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Unit Operations in Waste Treatment
concentration tends to reduce both con-
centration and recovery of centrifuged
solids. Centrate generally requires
retreatment. Requires suitable design
for a particular function, material and
flow and performs best at rated loading.
IH CHEMICAL UNIT OPERATIONS
For purposes of this outline a chemical unit
operation refers to a particular kind of chem-
ical transformation of feed stock (I. c. ). The
transformations may be inseparably associated
with both physical and biological changes, for
example, hydrolysis, oxidation and disinfection
are closely related to biological changes,
while coagulation, flocculation are closely
related to physical operations. These trans-
formations may be natural in origin or induced
by chemical additions. In a multicomponent
wastewater the control of treatment largely
is a compromise situation among operations
of biological-chemical-physical natures, some
favoring, some interfering, with the intended
function.
A Neutralization
The combination of excess acids and
alkaline materials to form a salt and
water is a recurrent natural process
called Neutralization. Among other
components, organisms release both
carbon dioxide (acidic) and ammonia
(alkaline) which neutralize each other to
form ammonium bicarbonate and water
Under certain conditions nature tends to
inhibit itself where an excess of acid or
alkaline materials are favored such as in
low pH deep waters or high pH surface
waters. Growth may become limited
because of pressure retention of excess
CO or rapid assimilation of C02
respectively This unbalance is unlikely
to be as serious as that due to local dis-
charge of acid or alkali released from
manmade sources. Neutralization is a
common requirement.
1 Favorable: Neutralization enhances the
probability for biological and certain
chemical transformations. Commonly
reduces corrosivity of acid waters.
Increases acceptability of acid or
alkaline waters for beneficial reuse
in water supply, recreation, wildlife,
agricultural industry and esthetics
2 Limitations: Generally high operating
and control cost. May produce gross
quantities of solids for disposal or
increase the dissolved solids in the
water. Requires close control to
prevent excessive additions.
B Oxidation
The oxidation of organic waste components
in water is a primary consideration in
wastewater stabilization. This process is
intimately linked with solids-liquid sep-
aration. For example, organic soluble
compounds may be oxidized biochemically
to form settleable agglomerates of cell
mass, to removable gaseous COg and to
less reactable water. Nitrogen compounds
may be converted to the oxidized state and
reduced to less reactable and removable
nitrogen gas.
1 The use of oxygen (aeration or surface
oxygenation) from air is by far the most
used unit operation for supplying
essential oxygen for intermediate and
terminal stabilization.
a Favorable: Generally available, low
cost. Necessary pumping, cleaning
and transfer equipment available at
reasonable cost. Moderate power
cost. Transfer capability reasonably
good. Dependable supply.
b Limitations: Limited solubility of
oxygen in contact with air. Large
capital investment in tankage and
space. Air solubility and transfer
limitations generally mean a low to
moderate rate process.
2 The use of commercial oxygen instead
of air permits a five-fold increase in
oxygen partial pressures.
a Favorable- Higher oxygen partial
pressures permit higher solubility
of oxygen in water and greater
5-5
i
-------
Unit Operations in Waste Treatment
oxygen transfer rate in high demand
situations. More likely to maintain
a higher residual DO in high rate
situations, or through the clarifier
stage. More complete stabilization
possible in less tankage and/or time.
High oxygen tension favors sludge
oxidation--lowers solids accumulation.
b Limitations: Better design require-
ments necessary to maintain high
oxygen use efficiency. More complex
system, more costly. Covered
tanks and oxygen production facilities
nearby usually required to favor
cost/benefit ratios. Requires better
operational control.
3 Ozone is another form of oxygen used
primarily for special purposes
a Favorable: Ozone is used primarily
for odor control because of its high
oxidizing energy and high activity in
water. Capable of reacting with
components that may not react with
oxygen under similar conditions.
b Limitations: Ozone (O^) is a highly
unstable compound. Generally
cannot be stored or made m high
concentrations. Usually requires
formation on site and use m pre-
treated water. High unit cost
Complex control.
4 Chlorine is commonly considered for
disinfection, disinfecting properties
are inherently associated with oxidizing
energy.
a Favorable: Commercially available
chemical, control equipment available,
operating controls generally known.
High energy material Relatively
simple operation Versatile material
capable of use in a variety of situations.
Cost higher than that for oxygen but
has a greater reactivity for many
beneficial operations. Rapid reaction
in most situations.
b Limitations Hazardous-nonspecific
toxicity in air or water. Chlorine
reaction produces HC1 during
reaction. Usually requires neutral-
ization. Highly corrosive in water
solution or wet gas. Certain com-
ponents such as ammonia prefer-
entially react with chlorine to cause
high chlorine demands. Requires
close control. Generally requires
pretreatment to avoid excessive
chlorine dosage.
5 Peroxy-acid oxidizing agents
Permanganate and dichromate are the
most common peroxy-acids used in
sanitary engineering. Permanganate
is relatively pH independent, dichromate
is an effective oxidant only under acid
conditions. Both have high oxidizing
energy for special purposes.
a Favorable: High oxidizing energy.
Capable of being separated from
product water. Adaptable for special
requirements such as destruction of
most organic materials or color.
Permanganate may occur naturally
in water and in excess its color is
its own indicator.
b Relatively high cost per unit of
oxidizing energy. Excess reagent
contributes to poor quality water.
Close control required. Commonly
does not oxidize ammonia nitrogen.
May require catalysis to reduce
delayed reactions
C Hydrolysis
The addition of water to split large
molecules into two or more simpler
substances is an inevitable part of
biodegradation. Cell mass may be
hydrolyzed to form smaller component
parts that are partially oxidized to yield
energy for building another crop of cells.
The process will continue as long as
oxidation energy is sufficient for growth.
Treatment tends to produce a low energy
5-6
k
-------
Unit Operations in Waste Treatmpnt
discharged effluent in which hydrolysis
and oxidation become lower rate operations -
(stabilized).
1 Favorable- Items favoring hydrolytic
cleavage (liquefaction) include high or
low pH, hydrolase enzymes or other
catalysts, high temperatures, low or
negative oxidation reduction potential
{low oxygen tension) or anything favoring
introduction of water into a complex
molecule.
2 Limitations: Any situation favoring
resynthesis of hydrolyzed components
into larger molecules reduces the net
effect of hydrolysis. Algal photo-
synthesis, bacterial or plant growth,
absence of toxic components, and
favorable conditions for growth usually
are associated with high rate hydrolysis
in a high energy situation but growth
may be the predominant reaction.
Any situation favoring dehydration
limits hydrolysis.
IV PROCESSES USED FOR THE REMOVAL
AND DISPOSAL OF ORGANIC MATERIAL
Isolation and stabilization are the key factors
in wastewater treatment. Unstable inter-
mediates must be stabilized to be acceptable
as gaseous or solid residues. Isolation refers
to separation of gaseous and solids residues
from the recombining media--water. It is
not possible to isolate or to stabilize to "end"
products--somewhere in time recycle will
occur. Each treatment operation is intended
to hasten recycle for beneficial use and delay
other types of recycle.
A Table 1 summarizes the functions of
various stages of treatment. Certain
unit operations are repeated at each
stage in a different manner.
TABLE 1
WASTEWATER TREATMENT STAGES
Preliminary or Pretreatment
1. Removal of roots, rocks, rags
2 Removal of sand, grit, gravel
3. To 'freshen11 the wastewater by short
term aeration, chlorination, grinding
or otherwise protect and promote sub-
sequent treatment
Primary Treatment
Removal of readily settleable or floatable
components
Secondary Treatment
Conversion of soluble or colloidal components
to removable form with partial stabilization
in process (commonly biodegradation).
Advanced Treatment of Wastewaters
Biological chemical or physical treatment
of used water to meet specific reuse quality
requirements. May consist of general or
specific item clean-up.
Solids Disposal
Nonpollutional takeout favoring conversion
to stable residues and separation of gas,
liquid, and solid phases.
B Tables 2 and 3 list selected unit operations
and the stages or processes in which they
may be used. Note that many of these
may occur repeatedly and that there is the
possibility of including one or more
options in any given treatment process
5-7
-------
Unit Operations in Waste Treatment
depending upon performance requirements
and nature of the problem. These lists of
physical (2) and chemical (3) operations
are not complete. It is not likely that all
of those listed may be included in any
modification of a treatment facility. The
problem is to select a series of operations
suitable to meet the performance require-
ments of the situation at a favorable cost/
benefit ratio.
Several processes are possible for
secondary treatment Each of these have
several modifications. The most common
are based upon biological-physical unit
operations. Chemical-physical operations
may be used to upgrade the overall
removal, or to remove specific components
commonly not sufficiently removed by
treatment. The same processes may be
used for advanced treatment providing the
degree of removal is upgraded on all
components of interest to meet specific
reuse requirements.
TABLE 2
UNIT OPERATIONS BY TREATMENT STAGE OR
PROCESS - PHYSICAL TRANSFORMATIONS
Unit Operation
Stage or Process51
Pre
Pri
Sec
Adv
AS
TF
OP
SP D
Fluid Transfer
liquid pumping
X
X
X
X
X
X
X
X X
mixing
X
X
X
X
X
X
X
X X
sludge pumping
X
X
X
X
X
X X
process residues-scum
X
X
X
X
X
X
Gas Transfer
into process-oxygenation
X
X
X
X
X
stripping
X
X
X
X
X
mixing
X
X
X
X
X
Solids Transfer
applied chemicals
X
X
X
X
X
process residues
X
X
X
X
X
X
X X
Heat Transfer
X
X X
Solids-Liquid Separation
coarse screening
X
micros creening
X
X
X
X
gravity sedimentation
X
X
X
X
X
X
X
X X
filtration
X
X
X
X
X
X
evaporation-drying
X
X X
distillation
X
floatation
X
X
X
X
X
X
X
thickening
X
X
X
X
X
X
c ent r ifu gation
X
X
X
X
X
X
adsorption
X
X
X
X
X
X
elutriation
X
X
X
X
X
X
X
x X
flocculation
X
X
X
X
X
X
X X
5-8
-------
Unit Operations in Waste Treatment
TABLE 3
UNIT OPERATIONS BY TREATMENT STAGE OR PROCESS
CHEMICAL TRANSFORMATIONS
Unit Operation
Pre
Pri
Stage or Process*
Sec Adv AS TF
OP
Oxidation Reduction
wet combustion
(biol-chem)
dry combustion
corrosion
bleaching (color removal)
Disinfection
Hydrolysis (liquefaction)
Solids-Liquid Separation
coagulation
precipitation
ion exchange
electrodialysis (phy-chem)
complexation
assimilation (biol-chem)
absorption (phy-chem)
Neutralization
SP
D
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
* Coding Tables 1 and 2
Pre - Preliminary or pretreatment stage
Pri - Primary clarification stage
Sec - Secondary treatment stage
Adv - Advanced treatment stage
AS - Activated sludge treatment process
TF - Trickling filtration treatment process
OP - Oxidation pond treatment process
SP - Sludge processing stage
D - Disposal stage (solids)
5-9
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Unit Operations in Waste Treatment
1 Activated sludge
This process is based upon a mixed
fluid suspension of solids concentrates
from previous operations and raw
wastewater in the presence of excess
oxygen to rapidly stabilize the incoming
pollutants by biological growth, trans-
fer to the solids phase, agglomeration
and solids liquid separation.
a Favorable Versatile process
capable of being adapted to high
performance on most types of
organic contaminants. Generally
capable of high efficiency in stabi-
lization and clarification. Lower
tankage and area requirements than
for most biological processes.
May be modified to achieve high
removal of nitrogen phosphorus and
solids. Adaptable to a wide range in
removal efficiency.
b Limitations: Requires close control
of load ratios and operating conditions.
High oxygen requirements. Subject
to upset by qualitative and quantitative
shock loads Unmodified process
commonly shows poor removal of
nitrogen and phosphorus. Subject to
the variations of characteristic of
biological treatment. High operating
cost.
2 Trickling filtration
Employs an attached media of sewage
slimes on the support surface for transfer
and stabilization of organic pollutants in
the influent
a Favorable: Versatile process capable
of being adapted for intermediate
performance on most types of organic
waste. Low operating cost. Adaptable
for a fairly wide range of removal on
substances showing good solids trans-
fer efficiency.
b Limitations- High capital cost for
land and tankage (rock or slag).
High pumping cost on manufactured
media. Generally not amenable for
coagulation and clarification Fewer
operating controls possible.
Subject to the variations character-
istic of biological treatment even
though it may not be as noticeable
due to generally turbid effluents
3 Oxidation ponds
Employs natural purification phenomena
of sedimentation, aerobic and anaerobic
degradation, algal photosynthesis
usually in a sacrificial pond or series
of ponds.
a Favorable: Capable of high treat-
ment efficiencies with low operational
cost. Adaptable to low or high
removal efficiencies depending on
land and capacity or time availability
Useful on a wide variety of waste-
waters. Land is available for
upgrading treatment and other uses
as needed. „
b Limitations: Generally limited to
application where land costs are
low. Subject to poor performance
during ice cover, overloads, spring
warmup and unexpected boil-up.
May be an odor nuisance at times.
Generally a low rate process with
poor solids recovery characteristics.
Appears to have a tendency to poorer
performance after several years of
operation.
4 Physical chemical treatment operations
Physical chemical treatment by lime
precipitation and activated carbon
adsorption is becoming recognized to
an increasing degree.
a Favorable: Is a versatile process
capable of being adapted to very
high degrees of treatment on a
variety of wastewaters. Recovery
of added lime and regeneration of
spent carbon by controlled incin-
eration permits chemical reuse and
reduces solids disposal. Relatively
low capital costs and space require-
ments. Capable of application over
5-10
-------
Unit Operations in Waste Treatment
wide flow variations with dosage
and regeneration time control.
Freedom from toxic effects.
b Limitations Generally higher
operating cost More complex,
process requires precise operational
control. May require pretreatment.
Chemical reuse almost mandatory to
limit solids disposal requirements.
Operating history for wastewater
applications scant.
D Sludge Processing or Disposal Routes
1 Wet combustion by aerobic biological
processes
Activated sludge, trickling filtration
and oxidation ponds involve a certain
amount of processing and disposal of
solids to a degree limited by the amount
of carbon dioxide and water formed in
process. Aerobic sludge digestion
accentuates solids disposal.
a Favorable- Generally a conventional
bio-chemical process using estab-
lished procedures. Time, oxygen
supply and favorable conditions are
basic requirements. Versatile for
a variety of wastes Generally
capable of a high degree of stabilization.
b Limitations: Process limited to a
residue solids level containing about
40% volatile content (10 to 2 0% of the
feed volatile solids). High liquid
recycle of N, P, and solids content.
Generally a long term operation.
Process interference serious for low
temperatures, toxic agents, or
unfavorable pH. Generally produces
a low concentration sludge ('v 2%).
2 Wet combustion--elevated temperature
and pressure
Wet combustion of organic wastes at
various pressures in enclosed vessels
with liquid temperatures of 350°F or
above have been effective for separation
of a highly stable mineralized ash.
a Favorable: Capable of producing
an easily separated high-mineral
ash. Rapid process low area
requirements, low solids disposal
volume.
b Limitations Requires complex
equipment and high heat require-
ments. Good control essential.
Residual liquid has a high color and
contaminant level.
3 Anaerobic digestion
This process is both a sludge con-
ditioning and a solids separation
process. Sludge residuals after
digestion are more concentrated in
solids content and decreased m volume
and mass due to escape of methane and
carbon dioxide gas or elutriate.
a Favorable; Versatile and dependable
process of organic stabilization for
suitable loading, mixing and tem-
peratures. Low cost operation.
Produces a usable product gas.
Residual solids relatively stable,
improved in concentration, and
drainability.
b Limitations Capital costs relatively
high for space and tankage.
Susceptible to shock loading, tem-
perature changes, poor mixing or
toxicity. Once upset--it requires
appreciable time and effort to
restore good performance. Recycle
liquids are high in dissolved and
suspended solids, are difficult to
treat.
4 Drying and incineration
Many modes of drying such as drying
beds, land spreading, flash drying are
possible with wet sludge Incineration
in a fluidized bed, rotary kiln or
multiple hearth are used. The multiple
hearth is one example of drying and
incineration.
a Favorable Dependable, versatile
operation for thick sludges where
5-11
-------
Unit Operations in Waste Treatment
heat release is close to heat require-
ments for water evaporation and
temperature rise. Can be controlled
to produce clean stack gases and
stable mineral solids residue. Rapid
process. Low area requirements
Control techniques well established.
b Limitations- Solids feed of low heat
and high water content may require
excessive auxiliary fuel cost.
Generally requires stack gas
reburning and solids recovery to
meet air quality requirements.
Generally costs about $50 plus per
ton of dry solids for operation.
Requires close control of feed,
burner temperature and other
operating variables.
5 Wet disposal of sludge
b Limitations. Good engineering and
farming practice are required.
The local residents do not appreciate
receiving waste materials from
elsewhere unless practice and
public relations are top rate.
"Possible hazards from surface
ground water and air pollution dim
the good neighbor policy.
A CKNOW LE DGMENT:
This outline contains appreciable material
from a previous outline by F. P. Nixon.
REFERENCES
1 Rose, Arthur and Elizabeth. Condensed
Chemical Dictionary, 7th Edition.
Reinhold Publishing Corporation.
New York. 1961.
Application of wet sludge to spoil areas,
stripped terrain, farm or marginal
land has been common practice for a
long time. Piping instead of truck
hauling is receiving increased con-
sideration to extend the disposal area.
2 APHA, ASCE, AWWA, WPCF.
Glossary, Water and Wastewater
Control Engineering. 1969.
3 Rich, Linvil G. Units Operations in
Sanitary Engineering. Wiley. 1961.
Favorable- Costs of disposal may
be reduced by avoiding costly drying
operations. Pumping of wet sludge
is more economical than hauling.
Possibilities for use of the organic
and water for reclamation of waste
land is attractive as a means of
recycling the wastes into the food
chain. Isolation possibilities are
improved by remote application
from population centers.
Rich, Linvil G. Unit Processes of
Sanitary Engineering. Wiley 1963.
This outline was prepared by F. J. Ludzack,
Chemist, National Training Center,
OWP, EPA, Cincinnati, OH 45226.
5-12
-------
WASTEWATER TREATMENT PLANT SAFETY PRACTICES
I INTRODUCTION
A Nature of Hazards
1 The hazards to which wastewater
treatment plant or wastewater pumping
station operators may be subjected in
the course of their work, include
exposure to:
a Physical injuries
b Body infections
c Noxious gases and vapors
d Oxygen deficiency
2 Hazards are real and preventive steps
are necessary if serious damage to life
and property are to be avoided.
B Prevention of Accidents
1 Occupational hazards can be avoided by:
a Proper design of wastewater pumping
stations and treatment plants
b Use of safety equipment
c Efficient administration and the
execution of safe practices.
II PREVENTION OF PHYSICA L INJURIES
A Treatment Plant Design
1 There are many danger spots around
wastewater treatment plant structures
at which fencing, chaining, railings and
guards are needed to safeguard
operators from physical injuries.
2 Good judgment and operating experience
are needed for the recommendation of
adequate fencing and railing protection.
3 Machinery should have guards for belts,
gears, and all exposed moving machine
parts. Adequate space should be
provided for machinery to facilitate safe
repair and maintenance.
4 All electrical equipment and wiring
should be properly insulated and
grounded. Suitable rubber mats
placed before switchboards should be
included.
5 Space should be provided for stairs and
handrails rather than ladders.
6 Many treatment plants are attended,
particularly at night, by only one
operator, whose safety deserves
special consideration. Adequate day
and night lighting for the grounds and
buildings is a necessity.
7 Plants using chemicals for treatment
of sewage or sludge should be provided
with an ample supply of potable water
for washing off chemical splashes or
spills on the body.
8 Fireproof buildings, including
sprinkler equipment are desirable.
Fireproofing is especially important
where large quantities of chlorine are
stored.
B Safety Equipment
1 Warning signs are needed near
dangerous machinery, blind obstacles
and for any hazardous location where
stumbling may occur.
2 Fire extinguishers of an approved
design should be placed in sufficient
number around the plant.
3 For entering deep tanks, and other
deep underground structures, the
wearing of a harness leather safety
belt should be mandatory, and at least
two men should be on guard at the
surface at all times that workers are
in these structures.
4 There are times when a life preserver
and throw-line On a settling tank rail
may prove its worth. Drowning is a
mishap that should not occur.
SA.TT.1.7.68
6-1
-------
Wastewater Treatment Plant Safety Practices
C Safe Practices
1 Structures and appurtenances of treat-
ment plants should be kept in good
repair and maintained in a tidy condition.
Tools should be picked up, manhole
covers promptly replaced, and every
effort made to promote good housekeeping,
2 Walkways should be kept free of grease,
oil and ice.
3 Safe procedures should be mandatory
for electrical maintenance.
4 Hazardous assignments should not be
undertaken without adequate personnel.
5 Accident-preventive instruction of
permanently legible character should
be prominently posted by management.
IU PREVENTION OF BODY INFECTIONS
A Treatment Plant Design
1 Clean and well equipped washrooms
should be provided.
2 Water foot-valves should be provided
on potable water supplies. Their use
will prevent contamination of plumbing
fixtures and reduce the probabilities of
reinfection while eating or smoking.
3 Clean dressing rooms equipped with
benches, mirror, and metal lockers
should be provided the workers for
changing to and from work clothes.
4 Plants should have well lighted and
equipped lunchrooms where workers
can prepare food and eat in clean
surroundings.
5 Swing doors (with glass ports) are
desirable for use in laboratories,
washrooms and locker rooms.
6 Cross connections between drinking-
water supply and sewage or sludge
piping or equipment should be strictly
forbidden and continuous diligence
exercised during construction and
operation to avoid them.
7 All bronze double check valves should
be installed on the water main leading
to sewage treatment plants. The
installation should allow for ready
checking of the valves for leakage.
The water service pipe for plant
drinking water should be taken off the
supply main just ahead of the double
check valves as an additional safeguard
to the employees.
B Safety Equipment
1 Emergency first-aid kits should be
available for treating minor cuts,
burns and wounds.
2 A 2 per cent tincture of iodine solution
is recommended for immediate use on
minor cuts or wounds.
3 Rubber gloves should be worn to
prevent infection while cleaning clogged
sludge pumps, handling screenings,
sewage, grit or other filth.
4 Coveralls or a complete change to
work clothes is recommended during
working hours.
C Safe Practices
1 A physician should treat all but minor
injuries.
2 Personal cleanliness should be
emphasized and direct contact with
sewage wastes should be discouraged.
3 Periodic inoculations against typhoid,
para-typhoid and tetanus should be
made available to personnel.
IV PREVENTION OF DANGERS FROM
NOXIOUS GASES AND VAPORS AND
OXYGEN DEFICIENCY
A Location of Hazards
6-2
-------
Wastewater Treatment Plant Safety Practices
1 In enclosed sewage screening comminutor
rooms where outfall sewers discharge
2 In covered tanks where organic matter
is decomposing, such as separate sludge
digestion tanks, septic tanks, sludge
storage tanks, sludge conditioning tanks,
or sewage screening bins
3 In digestion tank galleries or rooms
where sludge gas piping, gas boilers,
and gas appurtenances are located
4 In sludge gas storage tanks
B Types of Gases
b Sulfur dioxide (SOg)
c Phosphine
d Ethane (C_H„)
Z b
e Industrial waste gases: such as
carbon bisulphide, carbon tetra-
chloride and methyl chloride
2 Chlorine handling facilities.
Chlorinators should be located in a
room which can be heated and has
ample ventilation. The room should
be fireproof and equipped with
automatic sprinklers.
Dangerous gases which may be
encountered occasionally are.
a Ammonia (NH )
J
Equipment for the detection of various
gases and oxygen deficiency is shown
in Table 1:
TABLE l
SAFETY EQUIPMENT
Gas or Vapor Equipment for Detection
Hydrogen Sulphide 1. Lead acetate impregnated paper (qualitative)
2. Hydrogen sulphide detector (quantitative)
Methane 1. Combustible gas indicator or explosimeter
2. Oxygen-deficiency indicator
Carbon Dioxide, Oxygen-deficiency indicator
Nitrogen Oxygen-deficiency indicator
Oxygen Depletion Oxygen-deficiency indicator
Carbon Monoxide . 1. Carbon monoxide indicator
2. Carbon monoxide detector set
3. Carbon monoxide ampoules
Hydrogen 1. Combustible gas indicator or explosimeter
2. Oxygen-deficiency indicator
Gasoline 1. Combustible gas indicator or explosimeter
2. Oxygen-deficiency indicator for
concentrations over 0.3%
Sludge Digestion Tank Gas 1.
2.
Chlorine 1.
2.
Ammonia
Sulphur Dioxide
Ethane 1.
2.
Combustible gas indicator or explosimeter
Oxygen-deficiency indicator
Aqueous ammonia
Odor
Odor
Odor
Combustible gaa indicator or explosimeter
Oxygen-deficiency indicator
3
-------
Wastewater Treatment Plant Safety Practices
I
C Safety Equipment
1 The following safety equipment for the
plant should be included in the
specifications.
a Safety harness and recovery line
b First-aid kit
c Fire extinguishers (carbon dioxide
and soda ash-acid types)
d Portable combustible gas indicator
e Combustible gas alarms in hazardous
locations at large plants
f Oxygen deficiency indicator
g Portable air blower
h Hose mask or compressed-air,
demand-type mask
1 Two or more canister gas masks or
compressed-air masks for chlorine
leaks
j Miner's safety-cap lights
Cooperative efforts of designing engineers
in providing safe structures and of all
employees in exercising reasonable pre-
cautions in the course of their work are
needed. The responsibility of management
to provide adequate training in the safe
operation of all aspects of the wastewater
treatment plant is also mandatory.
REFERENCES
1 "Safety in Wastewater Works, " Manual
of Practice No. 1, FSIWA,
Washington, D. C. (1959)
2 "Sewage Treatment Plant Design, "
American Society of Civil Engineers
and the Water Pollution Control
Federation, Washington, D. C. (1959)
V SUMMARY
Because of the many hazards from gases,
infection and physical injuries in the operation
of wastewater treatment plants, maintenance
of such systems can be a dangerous occupation
if adequate safety precautions are disregarded.
By the use of sensible safety measures, these
dangers can be minimized and serious
accidents can be avoided.
This outline was prepared by Paul F.
Hallbach, Chemist, National Training
Center, FWQA, Cincinnati, OH 45226.
6-4
-------
SCREENING - METHODS AND PURPOSES
I GENERAL
Screening of wastewater is conducted as a
preliminary treatment step to remove large
suspended materials which may be harmful
to other plant operations.
II METHODS
In general, screening operations are of two
types:
A Screening
Screening and removal of solids for sub-
sequent disposal (usually by burial) is
generally achieved by using.
1 Bar screens or bar racks
2 Drum screens
3 Vibrating screens
4 Disc screens
The simplest form of screening, the bar
rack, consists of parallel vertical bars
inclined to the flow in order to facilitate
hand cleaning. This is accomplished by
means of a long-handled rake.
In some installations, fixed trash racks are
movable and can be raised for cleaning.
In this case, dual channels are needed in
order to have one rack in service at all
times.
Mechanical cleaning is done by moving
rakes attached to an endless chain.
(Figure 1)
Drum and disc screens are the most
widely accepted screens for domestic
sewage. Sewage flows through the screen
depositing material on the outside. As
the screen rotates, material is brushed or
jetted off into a screen pit where it is
removed by a bucket elevation.
(Figures 2 and 3)
SLID NC WIPCR'
PIVOTEO | \
DEFLECTOR
£FVir
4. SCREENINGS L
\ TROUC" f A
CHAIN GUIDE
FLOW
— -T
Figure 1 Vertical Section of Bar Screen and
Mechanical Rake.
Vibrating screens have received much
favorable acceptance in industrial
applications for removal of organic solids
which would otherwise drastically over-
load the treatment plant.
Solids removal by use of bar screens is
negligible. Fine screens average
approximately 10 percent removal of
suspended, solids and are primarily used
to remove fibrous industrial wastes.
B Comminution or Grinding
In cases where grit is not a problem, or
following grit removal, incoming material
is ground or chopped by means of
oscillating cutter bars to reduce large
materials to a size that can be handled
in the treatment processes.
SE.TT.pp. 22.11.68
7-1
-------
Screening - Methods and Purposes
Spray Pipe
•Chain
Guard
Drive
Unit
4—Refuse—-LI Water T.evf»l~l
Seal Wall
Front View
Figure 2
Disc Screen
There are three major types of equipment
in general use for reducing the size of
suspended solids:
1 The comminution consists of a rotating,
cutting screen. The sewage flow passes
through the screen and out the bottom
end of the rotating drum. (Figure 4)
2 Barminutors combine the design of the
bar screen with a travelling grinder
which moves up and down the rack to
shred the solids collected on the screen.
3 Grinders and shredders of varied design
are available for reducing the size of
solids removed from bar screens.
In addition, grinders are frequently used
at the waste source to reduce the solids
to an acceptable size. The home garbage
disposal unit and its commercial and
industrial counterpart are examples of
such units.
Screenings
Discharge
Trough
/X
Screen Covered
Drum
Spray Pipes
Drive
fluent
Effluent
End View
Figure 3. Drum Screen
7-2
-------
Screening - Methods and Purposes
Rotating, cutting
screen
w////////////m
Figure 4. Cutting Screen or Comminuter
III PURPOSES
A Protection
Removal of such solids as large sticks,
glass, metal, etc., protects the sewage
treatment equipment from damage.
B Reduce Maintenance
Removal or grinding of large suspended
solids such as rags, sticks, and certain
types of commercial and industrial wastes
reduces the potential of clogged pumps and
pipe lines with the attendant maintenance
problems.
C Increase Plant Efficiency
REFERENCES
1 Fair, G. M. and Geyer, J. C., Elements
of Water Supply and Waste Water
Disposal, John Wiley & Sons, (1958).
2 Water Pollution Control Federation,
Wastewater Treatment Plant Operator
Training Course Two, WPCA,
Washington, D. C., (1967).
3 Federation of Sewage and Industrial Wastes
Associations, Sewage Treatment Plant
Design, Washington, D. C, (1959).
4 Water Pollution Control Federation,
Operation of Wastewater Treatment
Plants, Washington, D. C., (1966).
Reducing the size of organic solids by
grinding or communition increases surface
area available to bacteria, thus improving
digester efficiency.
This outline was prepared by Lyman J.
Nielson, Chief, Training, Pacific Northwest
Water Laboratory, Corvallis, Oregon.
7-3
-------
GRIT REMOVAL - PRINCIPLES AND METHODS
I GENERAL
Grit chambers are used ahead of primary
treatment to remove heavy solids which may
be harmful to plant operation and equipment.
Grit consists primarily of inorganic materials
such as sand, gravel, cmders, glass, and
silt and may include organic materials such
as coffee grounds, fruit seeds, grain, rags,
paper and bits of meat and vegetables.
Removal of the inorganic substances in ad-
vance of pumps and treatment units prevents
wear of machinery and unwanted accumulation
of grit in settling tanks and facilitates the
handling of sludge produced by various treat-
ment processes.
In separate sanitary systems, grit originates
in wash water from kitchens and bathrooms,
from washings of floors and from illegal
ground or storm water connections and from
industrial processes.
In the case of combined sewer systems, in
addition to the above, sand and silt enter the
systems from street washings through catch
basins, from damaged pipe joints and drainage
from excavations.
II TYPES OF GRIT REMOVAL FACILITIES
Grit removal facilities can be classified into
two types
A Grit Chambers
Grit chambers are operated at velocities
low enough to permit capture of particles
of specific gravity 2.65 and 2 XlO'^cm
in diameter.
The design of grit chambers is based on
reducing the velocity of incoming sewage
to approximately 0. 5 to 1. 0 f/s for a
detention time of one minute. Generally
the decrease in velocity is accomplished
by an increase in cross sectional area.
Depending on the range in flow, it may be
necessary to provide more than one
chamber m order to maintain design
velocity. Chambers are also designed so
that the sewage enters and leaves the
chambers with a minimum of turbulence.
In smaller plants where mechanical grit
removal equipment is not feasible, at
least two chambers are required to permit
manual removal of accumulated grit.
(Figure 1) As manually cleaned chambers
do not produce a washed grit, a consider-
able amount of organic matter is included
with the grit. Mechanically cleaned grit
chambers are cleaned periodically by
some type of collection mechanism and
equipment for moving the collected grit
to a point of disposal.
B Detritus Tanks
Detritus tanks are operated at a relatively
constant level and produce a settled grit
containing considerable amounts of
organic material which must be removed
from the grit before disposal. This
material, or detritus, can be removed
by one of the following-
1 Re-suspension of the detritus by
injection of compressed air.
2 Detritus removal by use of a grit washer.
3 Mechanical scraper for grit removal
operated in such a manner as to flush
the detritus back into the sewage flow.
Ill DESIGN CONSIDERATIONS
Grit chamber design requires data on volume
and fluccuation of sewage flow and type and
quantity of grit.
A Quality
Grit types include sand, gravel, silt,
ashes, clinkers, and miscellaneous debris
washed from streets. Household dis-
charges, particularly from homes
SE.TT.pp. 23. 11.68
8-1
-------
Grit Removal - Principles and Methods
Area A
Plan
Jf/ffJJ
Weir
Grit
u
— ,
Vrv / I 7/ J 1 2A
Flushing sump
GRIT CHAMBER
Figure 1
equipped with garbage grinders, contribute
egg shells, bone chips, coffee grounds,
and similar material.
B Quantity
Quantities of grit vary depending upon
1 Street surface conditions
2 Area served by the sewer system
3 Climatic conditions
4 Types of sewer inlet structures
5 Maintenance of catch basins
6 Amount of storm water diverted from
system
7 Sewer grades
8 Condition of sewer system
9 Industrial wastes
10 Use of household grinders
C Design Theory
1 A principal feature of grit chamber
design is the use of differential
sedimentation. Successful grit
chamber operation is possible because
of the difference in settling rates
between inorganic grit particles and
organic slides.
2 Settling characteristics of the grit
particles to be removed provides the
basis for chamber design. The design
loading is normally expressed in
surface overflow rate with depth
qualified, or as linear flow velocity
with length as a qualifier.
8-2
-------
Grit Removal - Principles and Methods
Table 1 THEORETICAL MAXIMUM OVERFLOW RATES FOR GRIT CHAMBERS
Size of Grit
Particles,
Diameter,
mm
Average Settling Velocity of
Quartz Particles (specific
gravity 2. 65) in Water, Fpm
Theoretical Maximum Permissible
Overflow Rate for Substantially
Complete Removal (Gpd per Sq Ft)
Specific
Gravity 2. 65
Specific
Gravity 2. 0
Specific
Gravity 1.
CO
00
©
16.2
174, 500
105, 800
52,900
0.59
11.9
128, 000
77, 600
38, 800
0.42
8. 1
87,000
52, 800
26, 400
o
CO
o
6. 1
65, 500
39, 600
19, 800
0.25
5.4
58, 000
35, 200
17,600
0. 21
CO
46,300
28, 000
o
o
o
H
00
H
o
00
CO
40, 900
24, 800
12,400
0. 15
3.0
32.300
19, 600
9, 800
(Sewage Treatment Plant Design -- FSIWA Manual of Practice No. 8)
From Table 1 it can be seen that a grit
chamber designed to remove 100% of
minimum sized grit would also remove
all larger grit particles.
The theoretical detention time is that
required for the minimum size particle
to reach the bottom of the tank for
removal.
Other factors affecting removal of grit are
a Turbulence of flow in the chamber
which may hinder settling.
b Bottom scour is an important factor
in grit chamber efficiency. Re-
suspension and/or movement of
settled grit, because of the flow
velocity above a certain critical
velocity, may be the controlling
factor in determining flow velocity
in the chamber.
3 Velocity control
Because of variations in flow, it is
necessary to design the structure to
maintain the design velocity.
a Proportional weir
b Sutro weir
c Rectangular control section
d Parshall flume
e Mechanical velocity control devices
4 Other design considerations
a Accessibility of chamber and
appurtenances for cleaning and
maintenance
b Grit storage in chamber
c Method of grit removal
d Arrangement of units
REFERENCES
1 Fair, G.M. and Geyer, J. C. Elements
of Water Supply and Wastewater
Disposal, John Wiley & Sons, (1958).
8-3
-------
Grit Removal - Principles and Methods
2 Water Pollution Control Federation,
Wastewater Treatment Plant Operator
Training Course Two, WPCA,
Washington, D.C., (1967).
3 Federation of Sewage and Industrial Wastes
Associations, Sewage Treatment Plant
Design, Washington, D.C., (1959).
4 Water Pollution Control Federation,
Operation of Wastewater Treatment
Plants, Washington, D. C., (1966).
This outline was prepared by L». J. Nielson,
Sanitary Engineer, FWPCA Training
Activities, PNWL.
8-4
-------
FLOW MEASUREMENT DEVICES
I INTRODUCTION
Flow measurements are among the important
data collected as part of wastewater treatment
operations. Such measurements are used to
interpret treatment plant loadings, and are
required to assist the operator in evaluating
the overall plant condition. Flow data are also
valuable in determining and/or forecasting
future needs for plant expansion. If the
analysis of plant operation data involves quan-
titative considerations, the accurate measure-
ment of flow assumes a level of importance
equal to that of the laboratory and analytical
results.
In the following discussion procedures both
for measurement of stream flow and waste
discharges are described.
H FUNDAMENTS OF FLOW MEASUREMENT
Flow is the rate at which a volume of water is
transferred, or moves through a given section,
in time. Flow is commonly expressed in
equation form as:
Q - V/T
where- Q is the flow rate
V is the volume
T is time _
Other relationships are shown by:
v = 1/t and V = al
where- v is velocity
1 is the length of section having
cross-section area a
T is time
V is volume
Flow (Q) is obtained by measuring the cross-
sectional area (a) and velocity (v) of the water
moving past a point in the channel during a
specified time period (T).
Ill EQUIPMENT AND METHODS
A Gauging of Streams and Rivers
1 Current Meter
The current meter is a device for
measuring the velocity of a flowing
body of water. The stream cross
section is divided into a number of
smaller sections, and the average
velocity in each section is determined.
The discharge is then found by summing
the products of area and velocity of
each section.
2 Stage-discharge relationships
Large flows usually are measured by
development of and reference to a
stage-discharge curve; this procedure
has long been used by the U.S.
Geological Survey. Such gauging
stations are composed of a control
structure located downstream of the
location of measurement and some
type of water level indicator which
identifies the height of the water surface
above a previously determined datum.
Location of the control structure so that
reliable measurements of flow will be
obtained at all river stages is particularly
important. The water level may be
continuously recorded by an automatic
recorder located in a wet well or may
be indicated directly on a staff gauge
located at the bank of the river. Such
stations must be calibrated by measure-
ment of flow by velocity-area methods
(current meter) at all expected stages
of river flow.
3 Weirs
A weir may be "defined as a dam or
impediment to flow, over which the
discharge conforms to an equation.
The edge or top surface over which
the liquid flows is called the weir crest.
IN. SG.16.11.68
9-1
-------
Flow Measurement Devices
The sheet of liquid falling over the weir
is called the nappe. The difference in
elevation between the crest and the liquid
surface at a specified location, usually
a point upstream, is called the weir head.
Head-discharge equations based on pre-
cise installation requirements have been
developed for each type of weir. Weirs
so installed are called standard weirs.
Equations for non-standard installations
or unusual types may be derived
empirically.
Weirs are simple, reliable measurement
devices and have been investigated
extensively in controlled experiments.
They are usually installed to obtain
continuous or semi-continuous records
of discharge. Limitations of weirs
include difficulty during installation,
potential siltation in the weir pond, and
a relatively high head requirement,
0.4 - 2. 0 feet. Frequent errors in weir
installation include insufficient attention
to standard installation requirements
and failure to assure completely free
discharge of the nappe.
a Standard suppressed rectangular weir
This type of weir is essentially a dam
placed across a channel. The height
of the crest is so controlled that
construction of the nappe in the vertical
direction is fully developed. Since
the ends of the weir are coincident
with the sides of the channel lateral
contraction is impossible. This weir
requires a channel of rectangular
cross section, other special installation
conditions, and is rarely used in
plant survey work. It is more
commonly used to measure the dis-
charge of small streams.
The standard equation for discharge
of a suppressed rectangular weir
(Francis equation) is:
3/2
where
Q = 3.33 LH
Q = discharge, cfs
L ° length of the weir crest, feet
H ¦ weir head, feet
The performance of this type of weir
has been experimentally investigated
more intensively than that of other
weirs. At least six forms of the
discharge equation are commonly
employed. The standard suppressed
weir is sometimes used when data
must be unusually reliable.
b Standard contracted rectangular weir
The crest of this type of weir is
shaped like a rectangular notch. The
sides and level edge of the crest are
so removed from the sides and
bottom of the channel that contraction
of the nappe is fully developed in all
directions. This weir is commonly
used in both plant surveys and
measurement of stream discharge.
The standard equation for discharge
of a contracted rectangular weir
(corrected Francis equation) is:
where
Q = 3. 33 (L - 0. 2H)H
3/2
Q = discharge, cfs
L = length of the level crest edge,
feet
H = weir head, feet
\
0. 2H = correction for end contractions
as proposed by Francis
c Cipolletti weir
The Cipolletti weir is similar to the
contracted rectangular weir except
that the sides of the weir notch are
inclined outward at a slope of 1
horizontal to 4 vertical. Discharge
through a Cipolletti weir occurs as
though end contractions were absent
and the standard equation does not
include a corresponding factor for
correction.
9-2
-------
Flow Measurement Devices
The standard equation for discharge
of a 90° triangular weir (Cone
formula) is
Q = 2, 49H2" 48
where
Q = discharge, cfs
H = weir head, feet
The head on a triangular weir is
commonly measured at the crest
itself, rather than at a point
upstream. Crest height and head
are measured to and from the point
of the notch, respectively.
e Accuracy and installation
requirements
Figure 1. STANDARD CONTRACTED
RECTANGULAR WEIR
The standard equation for discharge
through a Cipolletti weir is
3/2
Q = 3. 367 LH '
where
Q = discharge, cfs
L = length of the level crest edge, feet
H = weir head, feet
The discharge of a Cipolletti
weir exceeds that of a suppressed
rectangular weir of equal crest
length by approximately 1 percent.
d Triangular weirs
The crest of a triangular weir is
shaped like a V-notch with sides
equally inclined from the vertical.
The central angle of the notch is
normally 60 or 90 degrees. Since
the triangular weir develops more
head at a given discharge than does
a rectangular shape, it is especially
useful for measurement of small
or varying flow. It is preferred for
discharges less than 1 cfs, is as
accurate as other shapes up to 10
cfs, and is commonly used in plant
surveys.
Quotations of weir accuracy express
the difference in performance between
two purportedly identical weirs and
do not include the effects of random
error in measurement of head. Weirs
installed according to the following
specifications should measure dis-
charge within ± 5% of the values
observed when the previously cited
standard equations were developed.
1) The upstream face of the bulkhead
and/ or weir plate shall be smooth
and in a vertical plane perpendicular
to the axis of the channel.
2) The crest edge shall be level, shall
have a square upstream corner,
and shall not exceed 0. 08 in.(2 mm)
in thickness. If the weir plate is
thicker than the prescribed crest
thickness the downstream corner
of the crest shall be relieved by a
45° champfer.
3) The pressure under the nappe
shall be atmospheric. The maxi-
mum water surface in the down-
stream channel shall be at least
0. 2 ft. below the weir crest.
Vents shall be provided at the
ends of standard suppressed weirs
to admit air to the space beneath
the nappe.
9-3
-------
Flow Measurement Devices
4) The approach channel shall be
straight and of uniform cross
section for a distance above the
weir of 15 to 20 times the max-
imum head, or shall be so
baffled that a normal distribution
of velocities exists in the flow
approaching the crest and the
water surface at the point of head
measurement is free of disturb-
ances. The cross-sectional area
of the approach channel shall be
at least 6 times the maximum
area of the nappe at the crest.
5) The height of the crest above the
bottom of the approach channel
shall be at least twice, and
preferably 3 times, the maximum
head and not less than 1 foot.
For the standard suppressed weir
the crest height shall be 5 times
the maximum head. The height
of triangular weirs shall be
measured from the channel
bottom to the point of the notch.
6) There shall be a clearance of at
least 3 times the maximum head
between the sides of the channel
and the intersection of the max-
imum water surface with the
sides of the weir notch.
7) For standard rectangular
suppressed, rectangular con-
tracted, and Cipolletti weirs
the maximum head shall not
exceed 1/3 the length of the
level crest edge.
8) The head on the weir shall be
taken as the difference in
elevation between the crest and
the water surface at a point
upstream a distance of 4 to 10
times the maximum head or a
minimum of 6 feet. For
triangular weirs the head shall
be taken as the difference m
elevation between the point of
the notch and the water surface
at the crest itself.
9) The head used to compute
discharge shall be the mean
of at least 10 separate measure-
ments taken at equal intervals.
The head range of the measuring
device shall be 0.2 - 1.5 feet.
The capacities of weirs which con-
form to these specifications are
indicated in Table 1.
4 Parshall flume
The Parshall flume is an open con-
stricted channel in which the rate of
flow is related to the upstream head
or to the difference between upstream
and downstream heads. It consists
of an entrance section with converging
vertical walls and level floor, a throat
section with parallel walls and floor
declining downstream, and an exit
section with diverging walls and floor
inclining downstream. Plan and
sectional views are shown in Figure 2.
Advantages of the Parshall flume
include a low head requirement,
dependable accuracy, large capacity
range, and self cleaning capability.
Its primary disadvantage is the high
cost of fabrication, this cost may be
avoided by use of a prefabricated
flume. Use of prefabricated flumes
during plant surveys is becoming
increasingly popular.
a Standard equations
The dimensions of Parshall flumes
are specified to insure agreement
with standard equations. Table of
dimensions are available from
several sources'*' For flumes
of 6 inch to 8 foot throat width the
following standard equations have
been developed.
1) 6 inch throat width
Q = 2.06 H 1,58
a
2) 9 inch throat width
Q = 3.07 H 1,53
a
9-4
-------
Flow Measurement Devices
TABLE 1 DISCHARGE OF STANDARD WEIRS
Crest Length
(Feet)
Contracted Rectangular*
Weir
(dlscharge-cfs)
Suppressed Rectangular*
Weir
(dlscharge-cfs)
Cipolletti*
Weir
(dls charge -cfs)
90O Triangular*
Weir
(discharge-cfs)
Max. Mm.
Max
Min.
Max
Min
Max Mm.
1. 0
590
28G
631
298
638
301
1.5
1 65
435
1
77
. 447
1
79
452
2. 0
3 34
584
3
65
596
3
69
602
2. 5
5.87
732
6
30
. 744
6
37
753
3 0
9 32
881
10
0
893
10
1
903
3. 5
13 8 1
03
14
8
1 04
15
0
1
05
4. 0
19 1 1
18
20
4
1. 19
20
6
1
20
4 5
25 6 1
33
27
5
1. 34
27
8
1.
35
6 55 046
5 0
28.8 1
48
30
6
1. 49
30
9
1
51
G. 0
34.9 1
78
36
7
1.79
37
1
1
81
'
7.0
41.0 2
07
42
8
2 08
43
3
2
11
8.0
47. 1 2
37
48
9
fO
V
00
49
5
2
41
9. 0
53.2 2
67
55
0
2 68
55
7
2
71
i
j
10.0
59.3 2
97
61
1
2. 98
62
0
3
01
* H- 0.2 ft, H - 1 5 ft. H - 1/3 L
verging
section
*o cticp
Throat section
A—
PLAN
,„Woter turfoce, *
FLOW
SECTION
FIGURE 2 PARSHALL FLUME
5
-------
Flow Measurement Devices
section where the water surface has
already begin to decline. Table 2
indicates thi total head requirements
of standard Parshall flumes. These
losses shonid be added to the normal
channel de/-th to determine the
elevation )f the water surface at the
flume entrance. No head losses are
indicated Jor discharge-throat width
combinati ms for which H is less
than 0.2 f.. or greater than 2/3 the
sidewall depth in the converging
section.
c Accuracy and installation require-
ments
A Parsliall flume will measure
discharge within + 5% of the standard
value i' the following conditions are
observed.
1) The dimensions of the flume shall
conform to standard specifications.
2) The downstream head, H^, shall
not ex 0. 2, H < 2. 0
a — a —
3) 1 to 8 foot throat width
1 522W 0,026
Q = 4WH
a
where
Q = free-flow discharge, defined
as that condition which exists
when the elevation of the
downstream water surface
above the crest, H^, does
not exceed a prescribed
percentage of the upstream
depth above the crest, H .
The prescribed percentage
of submergence is 60 percent
for 6 and 9 inch flumes and
70 percent for 1 to 8 foot
flumes
W = throat width, feet
H = upstream head above the
flume crest
b Head loss
The head required by a Parshall flume
is greater than (H - H^) because H is
measured at a point in the converging
9-6
-------
Flow Measurement Devices
3) The upstream head shall be
measured in a stilling well
connected to the flume by a pipe
approximately 1-1/2 inches in
diameter.
4) The flume shall be installed in a
straight channel with the centerline
of the flume parallel to the direction
of flow.
in which Q = the stream discharge,
S = the quantity of tracer added, c 3
the weighted average concentration
of tracer material during its passage
past the sampling point, and At = the
total time of the sampling period.
Disadvantages of tracer methods
include incomplete mixing, natural
adsorption and interference, and
high equipment costs.
5) The flume shall be so chosen,
installed, or baffled that a normal
distribution of velocities exists at
the flume entrance.
5 Tracer materials
Techniques, materials, and instruments
are presently being refined to permit
accurate measurement of instantaneous
or steady flow with several tracer
materials. Measurements are made by
one of two methods-
a Continuous addition of tracer
b Slug injection
With the first method, tracer is
injected into a stream at a continuous
and uniform rate; with the second a
single dose of tracer material is added.
Both methods depend on good trans-
verse mixing and uniform dispersion
throughout a stream. The concentra-
tion of tracer material is measured
downstream from the point of addition.
When continuous addition is employed,
flow rates are calculated from the
equation:
q . C = (Q + q) c
in which q = rate of tracer addition to
the stream at concentration, C,
Q 3 the stream flow rate, and c B the
resulting concentration of the stream
flow combined with the tracer. For
the slug injection method
Q
6 Floats
Floats may be used to estimate the time
of travel between two points a known
distance apart. The velocity so obtained
may be multiplied by 0. 85 to give the
average velocity in the vertical.
Knowing the mean velocity and the area
of the flowing stream, the discharge
may be estimated. Floats should be
employed only when other methods are
impractical.
B Pipes and Conduits
1 Weirs and Parshall flumes
Weirs and Parshall flumes are commonly
installed in manholes and junction boxes
and at outfalls to measure flow in pipes.
All conditions required for measurement
of open channel flow must be observed.
2 Venturi meters
Venturi meters, Dall tubes, and similar
type meters are useful in measuring
flow in pipes.
In the Venturi tube, the rate of flow is
expressed by:
D
Q = C (|)
V~2gh"
V5
where: C
D
a coefficient (usually unity)
diameter of entrance
c A t
D, = diameter of throat
9-7
-------
Flow Measurement Devices
g = acceleration due to gravity
h = difference between pressure at
entrance and at throat
Fig. 2a - VENTURI METER
3 Pilot tubes
Pilot tubes are useful in measuring flow
in closed conduits. It should be noted
that their use in measuring waste flows
is not recommended as waste solids may
plug the tube openings and render
erroneous readings.
4 Tracer materials
These methods are popular for measure-
ment of pipe flow because they do not
require installation of equipment or
modification of the flow. These are
especially convenient for measurement
of exfiltration and infiltration.
5 Depth-slope
If the depth of the flowing stream and the
slope of the sewer invert are known, the
discharge may be computed by means of
any one of several formulas.
a Manning formula
1.486 . _2/3„l/2
n " roughness coefficient
A = area of flow, sq. ft.
R = hydraulic radius, ft.
= area divided by wetted
perimeter, ft.
S ¦ slope, ft. per ft.
b Chezy formula
Q = CA \JRS
where
Q = discharge, cfs
C = friction coefficient
A = area of flow, sq. ft.
R = hydraulic radius, ft.
= area divided by wetted
perimeter, ft.
S = slope, ft. per ft.
6 Open end pipe flow
The following methods can be employed
when other more precise means are not
practical. They can be employed,
however, only when there is free dis-
charge to the air.
a Coordinate method
(Figures 3, 4, and 5)
Discharge may be computed by the
following formula
Q (gpm) =
1800 AX
where
Q
A R S
A = cross sectional area of liquid
in the pipe (sq. ft.)
X = distance between the end of the
pipe and the vertical gauge in
ft., measured parallel to the
pipe.
where
Q ¦ discharge, cfs
9-8
-------
Flow Measurement Devices
vertical distance from water
surface at the end of the pipe to
the intersection of the water
surface with the vertical gauge,
in ft.
Adjontoblo not so that
X Is parmllol to (
•ad T tils Is vertical-
— • (deptfl In sever) T-~
b = (dliuact trxm botto of pin to tart met of ftlllnj llqgld)
I'
Mr sloped imn or pipe*
OPEN-Pitt FLOW MEASUREMENT - THIS DEVICE, ADJUSTED TO THE
SLOPE OF A SEWER AND CALIBRATED, CAN THEN BE CLAMPED TO
THE SEWEJt OUTFALL
Figure 3
y=L
Por sloped pipes
OPEN-PIPE FLOW MEASUREMENT REQUIRES TWO DIMENSIONS THAT
LOCATE THE SURFACE OF STREAM AFTER IT LEAVES THE PIPE
{
then T • 1 ft
Velocity (V)
• 4 0 X
Discharge Id on
• 4 SO AV
V = Velocity - fps
A ¦ Crrrt*-nertlona1
area (an f I) nf
water In pipe
%
* (ft) to <*#ntor of strem
HOW TO MEASURE VELOCITY AND DISCHARGE FROM A PIPE.
Figure 5
b California pipe flow method
(Figure 6)
This method may be used only for
horizontal pipes having free dis-
charge. If the pipe is not horizontal,
a connection must be made to one
that is. The horizontal length must
be not less than 6 times the diameter
of the pipe. Discharge may be com-
puted by the following formula
Q (gpm) = T X W
where T = 3, 900 (1 - §) 1'88
d
W
2.48
where a and d are measured in feet
£
Opeo KM
"St.
At Leftist
* 6 d
%
BOSS |
CD
MEASUREMENTS NEEOED FOR
CALIFORNIA PIPE FLOW METHOD
IncllMd plpa atoald b* ceaMctad to
• korlzoatal ltnjth of pip* by tma
Figure 4
Figure 6
9-9
-------
Flow Measurement Devices
C Head Measuring Devices
Several of the above gauging methods
require the measurement of water level
in order that discharge may be determined.
Any device used for this purpose must be
referenced to some zero elevation. For
example, the zero elevation for weir
measurements is the elevation of the weir
crest. The choice of method is dependent
upon the degree of accuracy and the type
of record desired.
1 Hook gauge
The hook gauge measures water eleva-
tion from a fixed point. The hook is
dropped below the water surface and
then raised until the point of the hook
just breaks the surface. This method
probably will give the most precise
results when properly applied.
2 Staff gauge
The staff gauge is merely a graduated
scale placed in the water so that eleva-
tion may be read directly.
3 Plumb line
ACKNOWLEDGMENT:
Certain portions of this outline contains
training material from prior outlines by
P.E. Langdon, A.E. Becher, andP.F.
Atkins, Jr.
REFERENCES
1 Planning and Making Industrial Waste
Surveys - Ohio River Valley Water
Sanitation Commission.
2 Stream Gauging Procedure. U.S.
Geological Survey. Water Supply
Paper 888. (1943)
3 King, H.W. Handbook of Hydraulics.
4th Edition, McGraw-Hill. (1954)
4 Water Measurement Manual. United
States Department of the Interior,
Bureau of Reclamation. (1967)
This method involves measurement of
the distance from a fixed reference
point to the water surface, by dropping
a plumb line until it just touches the
water surface.
4 Water level recorder
This instrument is used when a continu-
ous record of water level is desired. A
float and counterweight are connected
by a steel tape which passes over a
pulley. The float should be placed in a
stilling well. A change in water level
causes the pulley to rotate which, through
a gearing system, moves a pen. The pen
traces water level on a chart which is
attached to a drum that is rotated by a
clock mechanism. When properly in-
stalled and maintained, the water level
recorder will provide an accurate,
continuous record.
This outline was prepared by F.P. Nixon,
Sanitary Engineer, FWPCA Training
Activities, SEC, and modified by L. J.
Nielson, Sanitary Engineer, FWPCA
Training Activities, PNWL.
9-10
-------
SEDIMENTATION BASIN'S IN WASTEWATER TREATMENT
I FUNCTION AND TYPE OF SEDIMENTA-
TION BASIN
A Function
1 Grit removal
2 Primary sedimentation
a Alone or in advance of other
processes
b With or without chemicals
3 Secondary sedimentation - following
biological treatment
4 Sludge thickening
B Shape and Type
1 Horizontal flow - mechanical sludge
removal
a Rectangular
b Circular
1) Center feed
2} Peripheral feed
c Imhoff tank
d Septic tank
2 Vertical flow
3 Tube settler^
II TYPICAL DESIGN CRITERIA
A Overflow Rates
Most State Standards specify maximum
overflow rates in primary tanks of from
600 to 1,000 gpd per square feet with
smaller plants using the lower rates.
In secondary clanfiers, maximum over-
flow rates of 800-1, 000 gpd per square
feet are commonly specified.
B Detention Time
Some states set limits on both maximum
overflow rate and minimum detention time.
A figure of 2 hours' detention for primary
tanks is common although shorter times
are permitted for primary tanks ahead of
activated sludge. For secondary tanks,
2 hours' detention is a common specification.
The Ten State Standards do not specify
detention times, but do set a minimum
depth of 7 feet on primary and 8 feet on
secondary tanks, which is tantamount for
setting a minimum detention time, since
rp „ 180 D
where T = Detention time (hours)
D = Tank depth (ft)
VD = Overflow rate (gpd per
sq. ft.)
Thus, a tank with an overflow rate of 600
gpd per sq. ft. and a depth of 7 ft. has a
detention time of 2. 1 hours.
C Weir Loading
A number of states specify weir loading
rates of the order of 10, 000-15, 000 gpd per
lin.ft. of effluent weir.
D Other Criteria
Some states specify minimum distances
from inlet to outlet, scum baffles are
commonly required, and, as a rule, some
requirement is set regarding even distri-
bution of flow and dissipation of kinetic
energy at the inlet.
Ill THEORY OF SEDIMENTATION
A Allen Hazen*
Hazen's paper published in the Transactions
of the American Society of Civil Engineers
in 1904 outlined the commonly accepted
theory of settling of discrete particles in
quiescent basins and discussed the effect
of departures from ideal conditions.
According to this theory sedimentation
efficiency is a function of overflow rate
and independent of depth.
2
B Thomas R. Camp
Camp's paper on the Transactions of the
American Society of Civil Engineers in
1946 elaborated on Hazen's theory, out-
lined the use of settling tube tests to
EN. DN. sb. 2. 7. 68
10-1
-------
Sedimentation Basins in Wastewater Treatment
determine the properties of suspensions,
discussed settling of flocculent suspensions,
scour of deposited materials, the effects of
short circuiting and turbulence. He recom-
mends the use of long shallow tanks for
sedimentation with the depth being limited
only by considerations of avoiding scouring
velocities and the need for sludge removal
equipment. This paper with the discussions
that accompany it is probably the best
single paper on the subject of sedimentation
basin design.
Quote from the discussion of the paper.
E. Sherman Chase: ". . . . the design
of practicable settling tanks will continue
to be based upon judgment, experience,
and common sense seasoned with a mod-
erate amount of theoretical computations
used as aids to judgment. "
T. R. Camp: "This attitude has undoubt-
edly been that of most of the designers of
tanks .... The moderate amount of
theoretical computations which Mr. Chase
suggests for seasoning the judgment has
unfortunately been so moderate that it has
been almost completely absent. Design
has consisted almost wholly of conformity
to previous practice in size and shape
with little regard for the principles in-
volved or for the nature and settling
characteristics of the particles to be
settled. "
C E. B. Fitch3
Fitch, in Sewage and Industrial Wastes in
1957, makes the point that in dealing with
flocculent suspensions a deep tank provides
better opportunity for particle growth than
a shallow one and hence that detention
time cannot be discarded as a criterion in
settling tank design. He also points out
that hydraulic efficiency or absence of
short circuiting is not necessarily impor-
tant to good tank performance.
D Ronald T. McLaughlin^
McLaughlin, in the Hydraulics Division
Journal of ASCE in December, 1959,
points out how the properties of the sus-
pension determine whether detention time,
overflow rate, or^both may be important
to efficient sedimentation.
IV COMPLICATING FACTORS
A Flocculation
Most of the suspensions dealt with in
wastewater treatment do flocculate.
Exception - Grit. Extreme case -
Activated sludge. Intermediate - Raw
sewage.
B Flow Variations
The typical wastewater treatment plant
is subject to wide variations in flow.
It is virtually impossible to design a
sedimentation tank that will behave in the
same way hydraulically with flow varying
by as much as a factor of 5-10 from maxi-
mum to minimum.
C Solids Removal
Sludge and scum removal mechanisms
perturb somewhat the settling of suspended
matter. It is necessary to consider a
portion of the tank volume ineffective be-
cause of the operation of these mechanisms
D Solids Concentration
k
It is commonly found that removal efficiency
of sedimentation basins is higher when deal-
ing with concentrated suspensions than when
influent concentrations of suspended solids
are low. It is not usually known why this is
so. In some cases, it may be due to differ-
ences in the size distribution of the sus-
pension. Many sewers act as crude settling
basins which are periodically flushed out
At times of flush-out, this relatively coarse
material reaches the treatment plant High
concentrations of suspended solids make for
more effective flocculation as well. This
accelerates settling
E Inlet Design
A portion of any tank is ineffective for
sedimentation because of need to dissipate
influent kinetic energy and distribute flow
evenly. In long tanks, the ineffective
fraction of the tank is smaller than in short
tanks. Flow variations and the necessity of
avoiding small openings usually prevent the
introduction of a controlling head loss to get
even flow distribution.
F Density Currents
Virtually all tanks are affected by density
currents. c Activated sludge secondary tanks
always have them, and most primary tanks
have them from time to time. Anderson^
has developed a design of secondary tank
with an annular weir to improve efficiency
of circular tanks. Gould in New York
adopted another way of coping with density
currents in rectangular secondary tanks.
He places the sludge hopper near the effluent
end of the tank instead of at the influent end.
10-2
-------
Sedimentation Basins in Wastewater Treatment
G Resuspension of Deposited Solids
This limits acceptable horizontal velocities.
Camp, using Shields formula, estimates
that velocities as high as 7-8 fpm are
acceptable. In primary tajiks at Hyperion,
there was evidence of resuspension when
velocities exceeded about 4 fpm. ® The
presence of density currents can affect
resuspension markedly. Burgess and his
colleagues studied flow patterns in the
primary tanks of the Northern Outfall
Works of the London County Council and
found a very marked density current.
V PLANT PERFORMANCE
Comparatively few extensive studies of plant
performance to guide engineer in design.
A NRC Study of Military Treatment Plants®
Studied 20 months of operating data from
18 primary plants. Mean BOD removal
for the 18 plants ranged from 10 per cent
to 61 per cent. Not only was there large
variation between plants but also large
variation in a given plant from one period
to the next. Average detention period for
the 18 plants was 3. 77 hours, average
overflow rate was 506 gpd per sq.ft.
Median displacement velocity was 0. 4 fpm.
Detention period correlated more closely
with removal efficiency than did overflow
rate. There was no significant difference
between circular and rectangular tanks,
other things being equal. The following
formula was used to fit the data for 10
plants where there was no recirculation to
the primary tanks-
Fractional Removal of
Suspended Solids
0. 67 T
= 1+ 0. 94 T
B Data in ASCE - WPCF Manual of Sewage
Treatment Plant Design
An analysis of data from 32 plants with
rectangular primary tanks and 25 plants
with circular primary tanks has been
made. The following table shows data on
size, loading, and performance at these
plants:
Rectangular
Tanks
Circular Tanks
Mean
Std Dev
Mean
Std D*v
Length or diameter
ft
118
53
86
32
Depth, ft
10 0
1 8S
10 5
1 98
Length/ width
3 77
1 40
.
-
Detention time, hrs
2 51
1 44
2 65
1 12
Overflow rate, gpd/ft^
097
535
856
360
Influent suspended
solids, mg/1
227
105
234
71
Effluent suspended
solids, mg/1
106
60
89
33
% removal suspended
solids
52 6
15 5
60 8
11
Multiple correlation analysis were made
on these data, using per cent removal of
suspended solids as the dependent variable
and various parameters as independent
variables. There was little to choose
between detention time and overflow rate
as variables in predicting performance.
There was no indication of marked superi-
ority of one shape of tank over the other.
As in the NRC study, there is a wide
scatter of points about the fitted curve.
Equations fitted to the data were
Circular Tanks
Fraction S. S. removed
2. 5 T
1 + 3.8T
and
2 940
Fraction S. S. removed = 4 i'qq + y
Rectangular Tanks
Fraction S. S. removed =
Fraction S. S. removed =¦
.49 T
I + . 55 T
1, 350
1, 920 + V
and
where T is detention time in hours
VQ is overflow rate in gallons per
day per square foot.
10-3
-------
Sedimentation Basins in Wastewater Treatment
C Secondary Clarifiers at Chicago Activated
Sludge Plants
A secondary clarifier in an activated sludge
plant is called upon to do a vastly more
efficient job of solids separation than one
expects of primary tanks. The influent
contains thousands of mg/1 ot suspended
solids and the effluent is expected to con-
tain only tens of mg/1 of suspended solids.
Thus, we look for 99 percent or more
removal of suspended solids. To achieve
this, it is essential that the activated
sludge be well flocculated and that only a
small amount of the suspended solids be
in small particles.
An analysis of two years operating data
from five of the operating batteries at
the three large Chicago activated sludge
plants has been made to get some insight
into the importance of various operating
variables in determining plant performance.
The analysis showed clearly the superiority
of the Anderson design with annular weirs
over the older design with peripheral weirs.
Overflow rate was not an important deter-
minant of effluent suspended solids,
although the five batteries had an average
overflow rate of over 1, 200 gpd per sq. ft.
Temperature had a significant effect on
clarifier efficiency. An organic loading
parameter, pounds of BOD per day per
pound of mixed liquor suspended solids,
had a greater effect than either of the other
variables.
The plants had average loadings oi . 19
pounds of BOD per day per pound of mixed
liquor suspended solids with a range of
monthly values of this parameter from
, 09 to . 51. Effluent suspended solids for
all of the plant units were 15 mg/1, with
monthly averages ranging from 5 to 96
mg/1.
Sludge volume index was not a significant
index of performance. It should be pointed
out, however, that sludge volume indices
were quite low, averaging 75 and varying
from 46 to 139.
This analysis indicates that with well
flocculated activated sludges excellent
solids separation can usually be obtained
at overflow rates considerably higher
than those usually recommended However,
from time to time one must expect the
system to get out of control and suspended
solids carry-over in the effluent to occur.
VI CONCLUSION
In spite of the fact that theoretical considera-
tions indicate that overflow rate should be
a more significant parameter than detention
time in design of sedimentation basins, plant
performance data do not support the superiority
of one design parameter over the other in
plants with conventional depths.
Sedimentation basins generally show rather
erratic performance in time. This is probably
due at least in part to the inherent instability
of flow patterns in basins with horizontal
velocities low enough to prevent resuspension
of deposited material. Flow fluctuations,
changes in waste composition, wind, and solar
radiation are other perturbing influences.
Although circular horizontal flow tanks are
notoriously prone to short circuiting their
performance in solids removal appears to be
as good as that of rectangular tanks similarly
loaded. The lower maintenance costs of sludge
removal mechanisms in circular tanks is
probably the most important factor in choosing
between circular and rectangular tanks.
There is no rational basis for the relatively
low overflow rates set by most of the state
design standards. At small plants where the
marginal cost of providing additional tank
capacity is proportionately much less than in
larger plants, there is probably not much
reason to skimp on basin size, but in larger
plants there may be significant economy in
using higher rates. Overflow rates much
higher than the conventional 600-1,000 gpd
per sq. ft. are used in many plants with good
efficiency.
There is little reason for maintaining low weir
loading rates in primary tanks. In secondary
tanks following activated sludge low weir
loadings, are important.
The tube settlers1® that have been introduced
recently have not as yet been tested enough
for any conclusion to be reached as to their
feneral usefulness in wastewater treatment,
his development will be watched with interest.
REFERENCES
1 Hazen, Allen. On Sedimentation. Trans.
ASCE, 53. 45-88. 1904.
2 Camp, Thomas R. Sedimentation and the
Design of Settling Tanks. Trans.
ASCE III. 895-957. 1946.
10-4
-------
Sedimentation Basins in Wastewater Treatment
Fitch, E. B. The Significance of
Detention in Sedimentation. Sewage
and Industrial Wastes 29. 1123-1133.
1957.
McLaughlin, Ronald T. , Jr The Settling
Properties of Suspensions. Proc.
ASCE Jour. Hydraulics Div. 85.
No. HY-12. 9-41. 1959.
Anderson, Norval E. Design of Final
Settling Tanks for Activated Sludge.
Sewage Works Journal 97. 50-65.
1945.
Theroux, Robert J. and Betz, Jack M.
Sedimentation and Preaeration Experi-
ments at Los Angeles Sewage and
Industrial Wastes 31. 1259-1266.
1959.
8 Subcommittee on Sewage Treatment.
National Research Council. Sewage
Treatment at Military Installations.
Sewage Works Journal 18, 789-1028.
1946.
9 Sewage Treatment Plant Design. WPCF
Manual of Practice No. 8. 90-91. 1959.
10 Hansen, Sigurd P., Culp, Gordon L., and
Stukenberg, John R. Practical Applica-
tion of Idealized Sedimentation Theory
Paper, Presented at WPCF Conference,
New York City. October 10, 1967.
Burgess, S. G., Green, A. F. , and
Easterby, Patricia A. More Detailed
Examination of Flow in Sewage Tanks,
Using Radioactive Tracers. Jour,
and Proc. Inst, of Sewage Purification,
Part 2. 184-192. 1960.
This outline was prepared by R. L. Woodward
Camp, Dresser and McKee Engineers, Boston
Massachusetts.
10-5
-------
SEDIMENTATION BASINS IN WASTEWATER TREATMENT
I FUNCTION AND TYPE OF SEDIMENTA-
TION BASIN
A Function
1 Grit removal
2 Primary sedimentation
a Alone or in advance of other
processes
b With or without chemicals
3 Secondary sedimentation - following
biological treatment
4 Sludge thickening
B Shape and Type
1 Horizontal flow - mechanical sludge
removal
a Rectangular
b Circular
1) Center feed
2) Peripheral feed
c Imhoff tank
d Septic tank
2 Vertical flow
3 Tube settler
II TYPICAL DESIGN CRITERIA
A Overflow Rates
Most State Standards specify maximum
overflow rates in primary tanks of from
600 to 1,000 gpd per square feet with
smaller plants using the lower rates.
In secondary clarifiers, maximum over-
flow rates of 800-1, 000 gpd per square
feet are commonly specified.
B Detention Time
Some states set limits on both maximum
overflow rate and minimum detention time.
A figure of 2 hours' detention for primary
tanks is common although shorter times
are permitted for primary tanks ahead of
activated sludge. For secondary tanks,
2 hours' detention is a common specification.
The Ten State Standards do not specify
detention times, but do set a minimum
depth of 7 feet on primary and 8 feet on
secondary tanks, which is tantamount for
setting a minimum detention time, since
rjl B 180 D
-vr
where T = Detention time (hours)
D = Tank depth (ft)
V0 = Overflow rate (gpd per
sq. ft. )
Thus, a tank with an overflow rate of 600
gpd per sq. ft. and a depth of 7 ft. has a
detention time of 2. 1 hours.
C Weir Loading
A number of states specify weir loading
rates of the order of 10, 000-15, 000 gpd per
lin. ft. of effluent weir.
D Other Criteria
Some states specify minimum distances
from inlet to outlet, scum baffles are
commonly required, and, as a rule, some
requirement is set regarding even distri-
bution of flow and dissipation of kinetic
energy at the inlet.
Ill THEORY OF SEDIMENTATION
A Allen Hazen*
Hazen's paper published in the Transactions
of the American Society of Civil Engineers
in 1904 outlined the commonly accepted
theory of settling of discrete particles in
quiescent basins and discussed the effect
of departures from ideal conditions.
According to this theory sedimentation
efficiency is a function of overflow rate
and independent of depth.
B Thomas R. Camp^
Camp's paper on the Transactions of the
American Society of Civil Engineers in
1946 elaborated on Hazen's theory, out-
lined the use of settling tube tests to
EN. DN. sb. 2. 7. 68
10-1
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Sedimentation Basins in Wastewater Treatment
determine the properties of suspensions,
discussed settling of flocculent suspensions,
scour of deposited materials, the effects of
short circuiting and turbulence. He recom-
mends the use of long shallow tanks for
sedimentation with the depth being limited
only by considerations of avoiding scouring
velocities and the need for sludge removal
equipment. This paper with the discussions
that accompany it is probably the best
single paper on the subject of sedimentation
basin design.
Quote from the discussion of the paper.
E. Sherman Chase: ". . . . the design
of practicable settling tanks will continue
to be based upon judgment, experience,
and common sense seasoned with a mod-
erate amount of theoretical computations
used as aids to judgment. "
T. R. Camp: "This attitude has undoubt-
edly been that of most of the designers of
tanks .... The moderate amount of
theoretical computations which Mr. Chase
suggests for seasoning the judgment has
unfortunately been so moderate that it has
been almost completely absent. Design
has consisted almost wholly of conformity
to previous practice in size and shape
with little regard for the principles in-
volved or for the nature and settling
characteristics of the particles to be
settled. "
C E. B. Fitch3
Fitch, in Sewage and Industrial Wastes in
1957, makes the point that in dealing with
flocculent suspensions a deep tank provides
better opportunity for particle growth than
a shallow one and hence that detention
time cannot be discarded as a criterion in
settling tank design. He also points out
that hydraulic efficiency or absence of
short circuiting is not necessarily impor-
tant to good tank performance.
D Ronald T. McLaughlin4
McLaughlin, in the Hydraulics Division
Journal of ASCE in December, 1959,
points out how the properties of the sus-
pension determine whether detention time,
overflow rate, or both may be important
to efficient sedimentation.
IV COMPLICATING FACTORS
A Flocculation
Most of the suspensions dealt with in
wastewater treatment do flocculate.
Exception - Grit. Extreme case -
Activated sludge. Intermediate - Raw
sewage.
B Flow Variations
The typical wastewater treatment plant
is subject to wide variations in flow.
It is virtually impossible to design a
sedimentation tank that will behave in the
same way hydraulically with flow varying
by as much as a factor of 5-10 from maxi-
mum to minimum.
C Solids Removal
Sludge and scum removal mechanisms
perturb somewhat the settling of suspended
matter. It is necessary to consider a
portion of the tank volume ineffective be-
cause of the operation of these mechanisms.
D Solids Concentration
It is commonly found that removal efficiency
of sedimentation basins is higher when deal-
ing with concentrated suspensions than when
influent concentrations of suspended solids
are low. It is not usually known why this is
so. In some cases, it may be due to differ-
ences in the size distribution of the sus-
pension Many sewers act as crude settling
basins which are periodically flushed out
At times of flush-out, this relatively coarse
material reaches the treatment plant High
concentrations of suspended solids make for
more effective flocculation as well This
accelerates settling.
E Inlet Design
A portion of any tank is ineffective for
sedimentation because of need to dissnjate
influent kinetic energy and distribute flow
evenly In long tanks, the ineffective
fraction of the tank is smaller than in short
tanks. Flow variations and the necessity of
avoiding small openings usually prevent the
introduction of a controlling head loss to get
even flow distribution.
F Density Currents
Virtually all tanks are affected by density
currents. Activated sludge secondary tanks
always have them, and most primary tanks
have them from time to time. Anderson^
has developed a design of secondary tank
with an annular weir to improve efficiency
of circular tanks. Gould in New York
adopted another way of coping with density
currents in rectangular secondary tanks.
He places the sludge hopper near the effluent
end of the tank instead of at the influent end.
10-2
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Sedimentation Basins in Wastewater Treatment
G Resuspension of Deposited Solids
This limits acceptable horizontal velocities.
Camp, using Shields formula, estimates
that velocities as high as 7-8 fpm are
acceptable. In primary tanks at Hyperion,
there was evidence of resuspension when
velocities exceeded about 4 fpm. ® The
presence of density currents can affect
resuspensmn markedly. Burgess and his
colleagues studied flow patterns in the
primary tanks of the Northern Outfall
Works of the London County Council and
found a very marked density current.
V PLANT PERFORMANCE
Comparatively few extensive studies of plant
performance to guide engineer in design.
A NRC Study of Military Treatment Plants®
Studied 20 months of operating data from
18 primary plants. Mean BOD removal
for the 18 plants ranged from 10 per cent
to 61 per cent. Not only was there large
variation between plants but also large
variation in a given plant from one period
to the next. Average detention period for
the 18 plants was 3. 77 hours, average
overflow rate was 506 gpd per sq. ft.
Median displacement velocity was 0. 4 fpm.
Detention period correlated more closely
with removal efficiency than did overflow
rate. There was no significant difference
between circular and rectangular tanks,
other things being equal. The following
formula was used to fit the data for 10
plants where there was no recirculation to
the primary tanks
Fractional Removal of
Suspended Solids
0. 67 T
= 1+ 0. 94 T
B Data in ASCE - WPCF Manual of Sewage
Treatment Plant Design
An analysis of data from 32 plants with
rectangular primary tanks and 25 plants
with circular primary tanks has been
made. The following table shows data on
size, loading, and performance at these
plants:
Rectanffular Tanks
Circular
Tanks
Mean
Std Dev
Mean
Std
Dpv
Length or diameter
ft
118
53
86
32
Depth, ft
10 9
1 85
10 5
1
93
Length/width
3 77
1 40
-
-
Detention time, hrs
2 53
1 44
2 65
1
12
Overflow rate, gpd/ft^
997
535
856
380
Influent suspended
solids, mg/1
227
105
234
71
Effluent suspended
solids, rng/1
106
60
89
33
% removal suspended
solids
52 6
15 5
60 8
11
Multiple correlation analysis were made
on these data, using per cent removal of
suspended solids as the dependent variable
and various parameters as independent
variables. There was little to choose
between detention time and overflow rate
as variables in predicting performance.
There was no indication of marked superi-
ority of one shape of tank over the other.
As in the NRC study, there is a wide
scatter of points about the fitted curve.
Equations fitted to the data were
Circular Tanks
Fraction S. S. removed =
2. 5 T
1 + 3. 8 T
and
Fraction S. S. removed = ^ y
Rectangular Tanks
Fraction S. S removed =
Fraction S. S. removed =
and
. 49 T
1 + . 55 T
1, 350
1, 920 + V
where T is detention time in hours
VQ is overflow rate in gallons per
day per square foot.
10-3
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Sedimentation Basins in Wastewater Treatment
C Secondary Clarifiers at Chicago Activated
Sludge Plants
A secondary clarifier in an activated sludge
plant is called upon to do a vastly more
efficient job of solids separation than one
expects of primary tanks. The influent
contains thousands of mg/1 oi suspended
solids and the effluent is expected to con-
tain only tens of mg/1 of suspended solids.
Thus, we look for 99 percent or more
removal of suspended solids. To achieve
this, it is essential that the activated
sludge be well flocculated and that only a
small amount of the suspended solids be
in small particles.
An analysis of two years operating data
from five of the operating batteries at
the three large Chicago activated sludge
plants has been made to get some insight
into the importance of various operating
variables in determining plant performance.
The analysis showed clearly the superiority
of the Anderson design with annular weirs
over the older design with peripheral weirs.
Overflow rate was not an important deter-
minant of effluent suspended solids,
although the five batteries had an average
overflow rate of over 1, 200 gpd per sq. ft.
Temperature had a significant effect on
clarifier efficiency. An organic loading
parameter, pounds of BOD per day per
pound of mixed liquor suspended solids,
had a greater effect than either of the other
variables.
The plants had average loadings ol . 19
pounds of BOD per day per pound of mixed
liquor suspended solids with a range of
monthly values of this parameter from
.09 to .51. Effluent suspended solids for
all of the plant units were 15 mg/1, with
monthly averages ranging from 5 to 96
mg/1.
Sludge volume index was not a significant
index of performance. It should be pointed
out, however, that sludge volume indices
were quite low, averaging 75 and varying
from 46 to 139.
VI CONCLUSION
In spite of the fact that theoretical considera-
tions indicate that overflow rate should be
a more significant parameter than detention
time in design of sedimentation basins, plant
performance data do not support the superiority
of one design parameter over the other in
plants with conventional depths.
Sedimentation basins generally show rather
erratic performance in time. This is probably
due at least in part to the inherent instability
of flow patterns in basins with horizontal
velocities low enough to prevent resuspension
of deposited material. Flow fluctuations,
changes in waste composition, wind, and solar
radiation are other perturbing influences.
Although circular horizontal flow tanks are
notoriously prone to short circuiting their
performance in solids removal appears to be
as good as that of rectangular tanks similarly
loaded. The lower maintenance costs of sludge
removal mechanisms in circular tanks is
probably the most important factor in choosing
between circular and rectangular tanks.
There is no rational basis for the relatively
low overflow rates set by most of the state
design standards. At small plants where the
marginal cost of providing additional tank
capacity is proportionately much less than in
larger plants, there is probably not much
reason to skimp on basin size, but in larger
plants there maybe significant economy in
using higher rates. Overflow rates much
higher than the conventional 600-1,000 gpd
per sq. ft. are used in many plants with good
efficiency.
There is little reason for maintaining low weir
loading rates in primary tanks. In secondary
tanks following activated sludge low weir
loadings are important.
The tube settlers*® that have been introduced
recently have not as yet been tested enough
for any conclusion to be reached as to their
general usefulness in wastewater treatment.
This development will be watched with interest.
REFERENCES
This analysis indicates that with well
flocculated activated sludges excellent
solids separation can usually be obtained
at overflow rates considerably higher
than those usually recommended However,
from time to time one must expect the
system to get out of control and suspended
solids carry-over in the effluent to occur.
1 Hazen, Allen. On Sedimentation. Trans.
ASCE, 53. 45-88. 1904.
2 Camp, Thomas R. Sedimentation and the
Design of Settling Tanks. Trans.
ASCE III. 895-957. 1946.
10-4
-------
Sedimentation Basins in Wastewater Treatment
3 Fitch, E. B. The Significance of
Detention in Sedimentation. Sewage
and Industrial Wastes 29. 1123-1133.
1957.
4 McLaughlin, Ronald T., Jr. The Settling
Properties of Suspensions. Proc.
ASCE Jour. Hydraulics Div. 85.
No. HY-12. 9-41. 1959.
5 Anderson, Norval E. Design of Final
Settling Tanks for Activated Sludge.
Sewage Works Journal 97. 50-65.
1945.
6 Theroux, Robert J. and Betz, Jack M.
Sedimentation and Preaeration Experi-
ments at Los Angeles Sewage and
Industrial Wastes 31. 1259-1266.
1959.
8 Subcommittee on Sewage Treatment.
National Research Council. Sewage
Treatment at Military Installations.
Sewage Works Journal 18. 789-1028
1946.
9 Sewage Treatment Plant Design. WPCF
Manual of Practice No. 8. 90-91. 1959.
10 Hansen, Sigurd P. , Culp, Gordon L. , and
Stukenberg, John R. Practical Applica-
tion of Idealized Sedimentation Theory
Paper, Presented at WPCF Conference,
New York City. October 10, 1967.
7 Burgess, S. G., Green, A. F. , and
Easterby, Patricia A. More Detailed
Examination of Flow in Sewage Tanks,
Using Radioactive Tracers. Jour,
and Proc. Inst, of Sewage Purification,
Part 2. 184-192. 1960.
This outline was prepared by R. L. Woodward,
Camp, Dresser and McKee Engineers, Boston,
Massachusetts.
10-5
-------
SEDIMENTATION TANK EQUIPMENT
I INTRODUCTION
The primary objectives of sedimentation
equipment is the removal of settleable solids
and floatable scum.
A Primary sedimentation objectives are to
remove concentrated sludge without
troublesome septicity.
B Secondary sedimentation requires prompt
return of fresh solids with concentration
as a secondary requirement.
C Basin, sludge collection, scum removal,
drive mechanisms and available equipment
will be discussed relative to A.and B
II SLUDGE COLLECTION EQUIPMENT
A General
Much equipment available, more similar-
ities than differences. Three basic shapes
of tanks- circular, rectangular, square.
B Circular Clarifier - Center Inlet
1 General
Most common flow pattern. Sewage
enters center well, either through side
of tank, or underneath and up. Sewage
flows downward, then radially, over a
peripheral weir.
2 Manufacturers
Infilco, Carter, Eimco, Yeomans, Dorr,
Rex, Walker, Link-Belt, Hardinge.
3 Beam Supported Type
Scraper blades mounted on truss
revolve about center shaft scraping
sludge to central well. Supported from
beams spanning tank. Full weight and
torque carried by beams. For small
tanks, usually 50 ft. in diameter or
less. Motor driven at center. Skimmer
connected to same shaft.
4 Center Column Type
For larger tanks up to 200 ft. diameter.
Scraping mechanism similar to beam
supported type. Scraper assembly
suspended from a turntable carried by
a central column. Rotated by means
of motor driven gears mounted on a
fixed bridge. Sewage enters up through
hollow column, then flows radially.
5 Peripheral Drive
Center column. Rotating bridge drives
scraping assembly. Driven peripherally
by motor driven wheels on wall of tank
Not too common in New England. Snow
and ice problems. Manufacturers:
Infilco, Eimco, Walker.
6 Suction Type
For secondary sludge, mainly activated
sludge. Suction pipes mounted on scraper
truss. Suction created by hydrostatic
head. Eimco, Dorr, Rex, Walker
7 Radial Chain Scraper Type
Not common. Radially mounted endless
chain type, scraping towards center
while rotating. Peripheral drive. Link-
Belt.
C Circular Clarifier - Peripheral Inlet
Sewage enters tangentially into a peripheral
race. Skirt extends to 18" from floor.
Sewage flows under skirt, then upward and
over central weir Scum, in theory, remains
in raceway. Sludge removal equipment
bridge supported. Lakeside, Yeomans, Rex.
D Rectangular Tanks
1 General
Sewage enters at end, is baffled, flows
longitudinally to other end, out over
weir.
2 Standard Chain Type
Oldest type. Chain and sprocket type.
Flights attached to chains run on rails.
Scrape sludge to hopper at inlet end
Cross collectors provided in hoppers
of large tanks. Rex, Walker, Link-Belt,
Yeomans, Jeffrey.
3 Moveable Bridge Type
Bridge spans tank width, running on rails.
Rakes hung from bridge contact floor and
move sludge to end of tank.
EN. DN sb. 3. 7. 68
11-1
-------
Sedimentation Tank Equipment
a Traction drive
Motor mounted on bridge. Electricity
supplied by reel and cable. Hardinge,
Link-Belt, Rex, Komline-Sanderson.
B Rectangular Tanks (Primary)
Return flights travel the surface forcing
scum to end. Usually picked up in a
revolving skimming pipe. Other types.
b Cable drive
Stationary drive at end of tank.
Pulls cables attached to moving
bridge. Dorr.
E Square Tanks
Flow can be center inlet, peripheral weir;
or straight across flow. Mechanism
similar to circular tanks except for exten-
sion arms which reach into corners, and
scrape sludge back to normal radius of
scraper. Not common. Dorr, Walker,
Link-Belt, Rex.
Ill SCUM REMOVAL MECHANISMS
C Secondary Tanks
It is not standard practice to install scum
removal mechanisms on secondary tanks
However, observations in Northeast Region
leads us to believe that they are needed.
We have been thinking ol making this a
firm requirement.
IV DRIVE MECHANISMS
Slow speed of rotation requires a large speed
reduction ratio. Various types of reducers
and gearing arrangements used, depending
upon diameter (or length) ot tank and sludge
load.
A Circular Tanks (Primary)
Skimming device rotates on center shaft.
Details vary, but all types torce scum
towards periphery where it is deposited
in scum box. Flows or is flushed to
scum pit. Peripheral feed: Scum in
raceway flows to a tilting skimming pipe.
Incomplete removal. Scum still rises
in main settling tank.
This outline was prepared by S. C Peterson,
Chiet, Construction Grants Activities, North-
east Region, FWPCA, Boston, Massachusetts
11-2
-------
CAUSES OF REDUCED EFFICIENCY
IN PRIMARY CLARIFICATION
I EXPECTED EFFICIENCY OF PRIMARY
TANKS IN MUNICIPAL SERVICE
A Settleable Solids
Over 99% of the settleable solids should be
removed In a properly designed and oper-
ated primary clarifier.
B Suspended Solids
Fifty to seventy percent of the suspended
solids should be removed in the primary
clarifier.
C Biochemical Oxygen Demand (BOD)
Thirty to thirty-five percent of the BOD
should be removed in primary clarification.
D Floating Solids
All of the floating solids, grease, scum,
etc. should be removed.
E Chemical coagulation of the influent to the
primary clarifier may increase removal
of B and C by ten to twenty percent or
more under controlled operation.
Preaeration, prechlorination and/or
coagulation would materially increase
the removable scum, grease and oil
either as floatable or settleable solids.
H CAUSES OF DIFFICULTIES AND REMEDIES
TO IMPROVE PERFORMANCE OF
PRIMARY CLARIFICATION
A Hydraulic overload of a periodic or chronic
nature may cause reduced retention time
and/or increased surface or weir overflow
rates. Improper distribution has a
similar effect.
1 Flow equalization by retention in the
collection system, surge tank, or basin,
during high flow periods may smooth
out the flow to give manageable control.
2 Improved baffling in the inlet structure
may decrease inlet flow velocities and
improve the tank fraction available for
clarification.
3 Proper distribution of flow among two
or more clarifiers in parallel operation
may greatly improve overall perform-
ance. Baffles converting the splitting
arrangement from an over to an under-
flow mode with 6-8 inch head and
adjustable spacing will help.
B Short circuiting as a result of improper
weir adjustment, placement or geometry
may cause exceptionally high overflow
velocities in limited tank sections with
obvious effects upon solids carryover.
1 Adjust weirs to insure proper leveling
and eliminate low spots or tilts.
2 Check weir positions. Are they
situated so that the natural upflow at
the end of a tank is not exaggerated by
weir position. Are the weirs spaced
geometrically to utilize the entire
surface of the tank?
3 Does the tank show excessive solids
carryover at corner positions. If so,
it may be necessary to block out
corner weirs.
4 Do you have sufficient weir length to
satisfy both surface overflow and
overflow per lineal feet of weir for the
situation.
5 Check prevailing wmd direction over
the surface. A windbreak of trees or
other type may prevent rolling action
with a downflow on one side, upflow on
the other side of the tank.
C Inadequate removal of sludge from the tank
may cause overlong solids retention with
development of septic conditions followed
by the production of floating solids masses
SE. TT. pp. 32. 7. 70
12-1
-------
Causes of Reduced Efficiency in Primary Clarification
and a sludge that is gasey and difficult to
move without exceptional resuspension.
1 Pump more frequently while the sludge
is in a fresher state and does not tend
to gas, cone, bridge, channel, or boil
upward to form resuspended or floating
solids.
2 Pump slowly enough to remove high con-
centration sludge instead of thin sludge
Sludge pumps should have variable
speed drives to permit adjustment of
pump rate in line with the situation.
3 Keep the sludge blanket low to prevent
excessive loading on flights or excessive
remixing of sludge and clarified liquor.
4 Adjust speed, flight position, and size
of flights so that their movement does
not cause undue turbulence and
resuspension of solids.
5 Inspect, repair and adjust sludge con-
veyor systems regularly to keep them
functioning properly. Sprocket wear on
long chains requires regular attention
to prevent excessive slack and possible
misalignment. For example, 0.005
inch wear on each of 400 links represents
2. 0 feet of extra slack,
6 Replace broken flight boards as needed
with properly sized and installed units
to hold the mechanism in line.
D Improperly adjusted scum baffles or
inadequate scum removal may cause scum
or floating solids to collect on discharge
weirs with obvious effects upon effluent
quality and plant appearance.
1 Adjust the scum baffles so that floating
solids will not go over, around or under
the baffle within usual ranges in plant
flow or water levels.
2 Remove scum frequently enough so that
unusual accumulations do not tend to be
swept under the baffle or cause undue
difficulty in the scum removal system
as a result of solidification into chunks,
balls or cake.
3 Inspect and adjust scum removal
equipment regularly to prevent or
correct plugged lines, scum clogged
conveyors, misalignment, improper
leveling, missing or nonfunctioning
scrapers or squeegies.
E Primary clarifiers may develop unfavor-
able density currents as a result of
temperature and salinity changes, inlet or
outlet characteristics,wind action, convey-
or characteristics and speed, or other
factors. For example, a significantly
warmer influent may rise to the top and
short circuit to the discharge weirs.
A colder influent may move along the
bottom until it reaches the outlet end and
cause undue upwelling against the end wall
of the tank. Highly saline influents may
have sufficient density to slide under the
lighter sludge masses.
1 Check sources of unusually warm, cold,
or saline discharges. Have them
decrease the amount, program the
discharge or improve mixing and
equalization at the plant intake.
2 Preaeration, equalization and mixing
at the plant will help to minimize
changes.
3 It may be necessary to decrease the
speed of sludge and scum flight
conveyors so that they have less
tendency to roll the tank contents or
make other adjustments to attain the
same objectives.
4 Weir placement, sludge withdrawal
rates, inlet baffles, sludge blanket
depth (or the distance from the top of
the sludge to the discharge level) may
require adjustment as discussed earlier.
F Good housekeeping and maintenance are
necessary for continued operation and
effective performance.
1 Regular cleanup, lubrication where
necessary, equipment checkout and
repair while the problem is small is
good economy, good public relations,
and good operational control.
12-2
-------
Causes of Reduced Efficiency in Primary Clarification
2 Wash or brush those effluent weirs,
flush sludge and scum lines to avoid
accumulation of excessive slime
growths, deposits or debris. Clear
pump lines after each use for sludge
or scum to avoid solidification in place.
Weir cleanup preferably should be a
daily operation.
3 Each man in the operational scheme
should be encourage to be on the look-
out for unusual noise, vibration,
appearance, or other behavior and to
report these to delegated authority
promptly. This report should include
pertinent information, location, and
seriousness of the problem. These
reports must be recognized and backed
by information feedback to the originator
by his supervisors regarding what may
or is being done about them. If they are
ignored the system and the operation
breaks down.
Ill Most operators are faced with the prob-
lem of making the best of what they have.
Often their ingenuity can mean the difference
between good and poor operation. The
operator on the line often is the best source
of information on precisely what is happening
or how it can be improved. Encourage an
exchange of information among all levels of
the staff to promote continuing education and
cooperative efforts.
This outline is an expansion of a previous
outline by Edgar R. Lynd, Municipal Waste
Treatment Program, State Sanitary Authority,
Portland, Oregon, F. J. Ludzack, Chemist,
National Training Center, FWQA.
12-3
-------
-------
SETTLING TANK OPERATION
I INTRODUCTION
The purpose of the settling tank is to remove
settleable solids and floating solids. Primary
and secondary clarifiers are of three basic
types: rectangular with mechanical collectors,
circular with mechanical collectors, and non
mechanically cleaned hopper bottom tanks.
E SCUM REMOVAL
A Operation
1 The objective in the operation of the
skimmer or scum trough is to get the
thick scum into the scum pit, while
keeping the surface of the clarifier
free from floating solids.
2 Reducing the amount of the scum which
will be pumped to the digester should
be considered. It will help to pump the
scum back ahead of the comminutor
thus grinding it and giving it another
chance to settle out in the tank.
3 The skimmer should be hosed and
swept clean daily. The scum pit should
also be cleaned out after each pumping.
4 Removal of scum from the scum pit
should be effected daily.
5 Crank case oil should be separated and
buried. Under no condition should it
or similar material be pumped to the
digester.
B Excessive Scum Formation
1 Industrial wastes are frequently the
cause of considerable quantities of
floating solids. Pretreatment screens
are often removed and when evidence
of this condition occurs, the industry
should be contacted.
2 Inadequate scum removal often results
from the gasification and subsequent
rising of sludge and will be treated
under sludge removal.
3 In circular mechanically cleaned
clarifiers the skimming belting often
warps out of shape and ineffectively
moves the scum. Whenever the
belting fails to do a good job, it should
be replaced.
4 Septic sewage devoid of dissolved
oxygen will cause gasification of the
particles settling and much of the
incoming sludge will float. This will
be treated under testing and inter-
pretation of control.
Ill SLUDGE REMOVAL
Sludge removal not only affects the quality
of the effluents from the primary and
secondary treatment units, but also is a
most important feature in the operation of
the digester.
A Pumping periods must be frequent enough
to prevent gasification of sludge in the
hoppers, but periods must not be so
frequent that sewage instead of sludge is
pumped to the digester.
B If the slopes of the sludge hopper are not
sufficient, sludge may adhere to the slope.
Plants which have hopper slopes less than
1.4 vertical to one horizontal will
probably find that it is necessary to rod
the hoppers to keep the sludge from
sticking.
C Sludge pump should have some method of
varying the speed or pumping rate and
should be set to pump less than 50 gallons
a minute. If the pumping rate is too fast
sewage will be pumped through a hole in
SE. TT. pp. 33. 8. 70
13-1
-------
Settling Tank Operation
the sludge blanket in the hopper and the
sludge on the side of the hopper will
remain there until it gasifies and rises in
chunks.
D Practice of pumping more water (a thin
sludge) to the digester than is actually
needed will cause the digester to operate
unsatisfactorily, because there is so much
water, there is not enough room for solids.
E The daily variation in the strength of sewage
will cause an increase or reduction in the
quantity of solids deposited as sludge.
It is often necessary to run settleable
solid tests on the raw sewage through a
24-hour period to get a 24-hour picture
of the variation of solids loading.
F Maximum duration of pumping should be
figured and at no single pumping period
should the total gallons pumped be greater
than the capacity of the hoppers in gallons.
G Every plant should be able to see or
sample the raw sludge. This is the best
guide to obtaining a thick sludge. However,
many experienced operators have never
taken the time to run enough percent solid
tests to train their eyes so that they can
tell what a thick sludge really is. If
possible, stop pumping when the sludge
contains less than 4% solids.
H Supernatant solids entering a primary
clarifier will necessitate extra pumping
time. It is desirable to turn a supernatant
high in solids to the drying bed rather than
to allow it to return and upset a primary
clarifier.
I Quantities of sludge can be estimated by
running the settleable solids tests on the
influents of the settling tank. For example
at a flow of 150, 000 gallons per day in the
settleable solids of 6 ml/1 in the raw sewage,
the non compacted sludge would be about
. 006 X 150, 000 gallons equals 900 gallons
of sludge to be pumped once daily.
J Considerable compaction can be effected
in the hoppers of the clarifier if the size
indicates that the sludge can be left in the
hoppers for a longer period of time without
becoming septic. On a once a day pumping
schedule, it may be found that about one
half of the theoretical amount of sludge
figured under Part 9, can be pumped into
the digesters and leave the the hoppers
empty.
K Time clock operation is often necessary
where the hopper capacity is limited if
the effluent DO indicates that the sludge
cannot remain in the clarifiers for a
longer period of time. Hourly pumping
can be estimated by the settleable solid
tests taken at hourly intervals during the
24-hour period as mentioned under Part 5.
It is also possible to set the time clock
to pump 1/2 the calculated theoretical
amount of sludge and then remove the
excess sludge at two manual pumping
periods during the day.
IV WEIRS, BAFFLES AND LAUNDERS
Weir placement, adjustment and maintenance
govern the fraction of tank volume and sur-
face available for clarification.
A Cleaning--The weirs scum baffles and
launders should be hosed and scrubbed
clean with a stiff broom daily. Weirs
located at the ends of rectangular tanks
occasionally have large particles of sludge
going over the weir. This phenomenon is
usually caused by solids creeping up the
end of a tank which has a heavy growth
on it. This creep can be minimized by
keeping the scum baffles and weirs clean
far below the water surface.
B Settling of the tank structure often causes
weirs to allow more water to flow over
one portion of the tank than over another.
Most weirs are bolted through slots to
permit leveling. When adjustments are
made the operators should arrange to have
a transit or level available to set the weirs
properly. A weir which is not level will
result in short circuiting.
C Occasionally weirs are not of sufficient
length to accommodate the necessary flow.
For every 10, 000 gallons of sewage daily,
it is necessary to have one foot of weir
length or more.
13-2
-------
Settling Tank Operation
D Baffling is necessary especially in
rectangular tanks in order to prevent
short circuiting. Stratification often
occurs in such tanks due to difference
in temperature of sewage at the top or
bottom of the tank and it becomes
necessary to deflect the thermal currents
by baffling. In the winter it is sometimes
necessary to put a baffle at the head of
the tank to get the warm sewage to drop
down to the bottom of the tank and under
the baffle.
E Occasionally the channel carrying the
clarified liquid which has passed over
the weirs will have insufficient capacity
to carry the necessary quantity of sewage,
which will back up and submerge the weir.
This may be due to defects in the design
of the launder itself or in the piping.
Additional pipe or channel capacity may
be necessary for relief.
B Overflow Rate--When a plant has the
flexibility designed into it to permit
operation of more than one primary
settling tank, it is necessary to try to
operate a clarifier at a satisfactory
surface loading. The average plant
will operate satisfactorily at surface
loading of between 600 and 900 gallons
per sq ft per day.
C Temperature of Sewage--Temperature
has a pronounced affect on the settling
of sewage. In cold weather, there is
usually an ample supply of oxygen and
settling is retarded by the viscosity of
the sewage. In the summertime the
viscosity of the sewage is low, but there
is usually the lack of dissolved oxygen
and the solids start to digest, producing
gas bubbles which attach themselves to
the sludge particles and lift them to the
surface of the clarifier.
V CONTROL
Factors Affecting Control
A Detention Period--Most primary treatment
units will operate satisfactorily with
detention periods from 1 1/2 to 3 hours.
Cold weather and the resulting low tem-
peratures increase the viscosity of the
sewage and settling is much slower.
With a long detention period and summer-
time high temperatures, the plant's
efficiency may be reduced by a septic
sewage condition. This condition is
brought on by the fact that at higher
temperatures, oxygen absorption into the
sewage is slow and the bacterial rate of
using up the oxygen is accelerated.
This outline was prepared by J. A.
Montgomery, Sanitary Engineer, FWQA
Manpower and Training Activities, PNWL,
Corvallis, OR.
13-3
-------
Settling Tank Operation
PRIMARY CLARIFIER CONTROL CHART
Effluent
Settleable
Solids
In ml/1
Dissolved Oxygen
Influent Effluent
Condition
Probable Cause
Remedy
T-.3
Over 2. 0
Over 2. 0
Excellent
T-.3
Over 2. 0
2.0-. 1
Fair
Warm or strong sewage
1,2,3
T-.3
Over 2.0
0
Unsatisfactory
Warm or strong sewage
1,2.3
T-.3
2.0-.1
Over 2.0
Good
Cold or weak sewage
T-.3
2.0-.1
2.0-. 1
Poor
Stale raw sewage
1
T-.3
2.0-.1
0
Unsatisfactory
Warm stale strong sewage
1.2,3
T-.3
0
Over 2. 0
Good
Septic cold or weak sewage
4, 5.6
T-.3
0
2.0-.1
Poor
Septic sewage
2,4,5,6
T-.3
0
0
Very Bad
Warm strong septic sewage
1,2,3,4, 5,6
Over . 3
Over 2.0
Over 2. 0
Poor
Too much sewage
7
Over . 3
Over 2.0
2.0-. 1
Poor
Too much strong sewage
7,2,3
Over . 3
Over 2. 0
0
Unsatisfactory
Overloaded hydraulically
and Organically
2, 3
Over . 3
2.0-.1
2. 0
Poor
Too much stale cold sewage
7
Over . 3
2.l-.l
2.1-. 1
Poor
Too much stale sewage
2,7
Over . 3
2.l-.l
0
Unsatisfactory
Too much stale or warm
strong sewage
2. 3
Over . 3
0
Over 2. 0
Fair
Too much septic cold sewage 1,4, 5, 6
Over . 3
0
2.l-.l
Unsatisfactory
Too much septic sewage
7,2, 4,5,6
Over . 3
0
0
Terrible
Many reasons
2,3,4,5,6
REMEDY:
1. Increase flow to primary clarifier.
2. Prechlorinate so that no chlorine residual is in the effluent.
3. Add aeration or recirculation high in D. O.
4. Add upsewer chlorination so that no chlorine residual in plant influent.
5. Flush sewers routinely,
6. Move sewage rapidly through lift station.
7. Decrease flow to primary clarifier.
13-4
-------
ANAEROBIC PROCESS PRINCIPLES
I INTRODUCTION
Anaerobic decomposition is employed for the
treatment of organic sludges and concentrated
organic industrial wastes. During the process
volatile organic matter is degraded through
successive steps to gaseous end products.
These are primarily C02 and CH4. Since
molecular oxygen is absent, the removal of
methane and other reduced gases represents
the BOD removal from waste under anaerobic
digestion.
A Theory
1 Organic sludges go through two basic
processes during the digestion process--
liquefaction and gasification. Liquefaction
occurs with extracellular enzymes which
hydrolyze complex carbohydrates to
simple sugars, proteins to peptides and
amino AQids and fats to glycerol and fatty
acids.
2 The ultimate end products of the lique-
faction process are primarily volatile
organic acids which are produced by
"acid producing" strains of bacteria.
The acids produced are primarily acetic,
butyric and propionic.
3 During gasification the end products of
liquefaction are further broken down
to gaseous end products. The principal
components of this gaseous mixture are
CO2 and CH4. During a well balanced
digestion process, the processes of
liquefaction and gasification occur
simultaneously.
4 The degree to which the various substances
present in sewage sludges and industrial
wastes will be decomposed will depend on
their chemical nature. Woody type ma-
terial will result in approximately a 40
percent humus-like residue. Soluble
organics are almost completely
decomposed. With the exception of
hydrocarbons, carbonaceous material
is quantitatively converted to CH4 and
CO9. Free fatty acids will undergo
80-90 percent destruction, ester fatty
acids 65-85 percent and unsaponifiable
matter 0-40 percent.
5 It has been found convenient to describe
the digestion process in three stages:
a Acid fermentation stage
b Acid regression stage
c Alkaline fermentation stage
The course of digestion of this three
stage digestion process is shown graphi-
cally in Figure 1.
B Acid Fermentation Stage
During the acid fermentation stage,
carbohydrates (sugars, starches, etc. )
are broken down to low molecular weight
fatty acids, primarily acetic, butyric and
propionic. This intensive acid production
results in a drop in pH and leads to the
formation of putrefactive odors.' ^ The
organisms primarily responsible for this
stage of the digestion process are called
"acid formers. " They transform the waste
into short chain fatty acids and are generally
anaerobic or facultatively anaerobic. This
group encompasses a large number of bac-
teria with a wide range of talents. As a rule,
the acid formers are less sensitive to
environmental factors than are the methane
formers. Many of the acid formers are
quite versatile as to substrate and end
product while others are quite limited.
Hence, in some cases, components of the
waste may be taken to short fatty acids by
a single organism, while in other cases,
this transformation may require several
organisms.
C Acid Regression Stage
During the acid regression stage, decom-
position of organic acids and soluble
nitrogenous compounds occurs resulting
in the formation of ammonia, amines,
acid carbonates and small quantities of
CO^, Ng, CH4 and H2. The pH will tend
to increase during this stage. By-products
resulting from acid regression will include
H2S, indole, skatol and mercaptans.
D Alkaline Fermentation Stage
During the alkaline fermentation stage,
destruction of celluloses and nitrogenous
compounds occur. Low molecular weight
organic acids produced during the earlier
stages of the process are broken down to
CO2 and CH4. The organisms primarily
responsible for the process are the
SE. AN 8. 8. 70
14-1
-------
Anaerobic Process Principles
Acid fermentation
Acid regression
Digestion of resistant materials
1-0
0-5
0L 5L
1-0
^0-5
4
*
»•%
1» /
¦ It
¦ /'/
^ f Acidity
/NHj-N \
/— \
/ /;
* / »
/ —r
' 1
^7 / *
! f
tlh
hk--
(,*
V-* , pH
_ / ,-"S-
if *s
" Relative ga
1
/' \
~ 1
~
s production " -
30
50
40
150
30
220
Time of digestion, days
Course of digestion of sewage solids (after Grune, 1956)
FIGURE 1
spore-forming anaerobes, the methane
bacteria, and fat-splitting organisms.
The methane bacteria are strict anaerobes,
nonspore forming and require CO2 as an
hydrogen donator. These organisms require
an inorganic nitrogen source (NH3). The
effective pH range for methane formation
is pH 6. 4-7. 2.
E Gas Production
The gas produced from the digestion of
sewage sludge and similar organic mixtures
is composed primarily of CO, and CH4 with
small quantities of NH3l H2S, H2, N2 and
Oq present. Gas from a well-digesting
sludge mixture will contain 25-35 percent
CO9 and 65-75 percent CH4. A gas yield
of 16-18 ftJ/lb of volatile matter destroyed
can be expected from digesting sewage
sludge. The following table from Buswell
(1939) shows gas production from various
Sewage constituents.
ch4
Material
%
F ats
62-72
Scum
70-75
Grease
68
Crude fibre
45-50
Protein
73
ft of gas/lb
decomposed
18-23
14-16
17
13
12
II TYPE OF ANAEROBIC PROCESSES
A "Conventional" process generally used for
treatment of concentrated wastes such as
primary and secondary sludges such as at
municipal sewage treatment plants.
B "Anaerobic contact process" designed to
handle more dilute wastes and generally
applied to specific industrial wastes.
C Process Units
1 Septic tanks
2 Imhoff tank
14-2
-------
Anaerobic Process Principles
3 Conventional digesters
a Standard
b High rate^
4 Anaerobic contact
5 Anaerobic lagoons
III ENVIRONMENTAL FACTORS
A Biological - Nutrients^
1 Nitrogen and phosphorous - usually
present in sufficient amounts in domestic
wastes - may be required in some indus-
trial wastes. Nitrogen must be added in
NHg form, as NO2, NO3 forms are re-
duced and N2 is evolved, hence lost.
2 Trace elements - Fe|8' Mn, Mg, K, Ca,
S, etc. - seldom a problem as waste
usually contains sufficient amounts.
B Physical
1 Hydraulic loading
2 Temperature
a Mesophilic 85° to 100°F
b Thermophilic 120° to 135°F
3 Mixing
C Chemical
1 pH - range from about 6.6 to 7.6
2 Toxic materials
a Certain alkali and alkaline-earth
are stimulatory at low levels and
inhibitory aJLhigher levels as shown
in Table 1. ' '
b Ammonia toxicity
c Sulfide toxicity^®^
d Heavy metal toxicity^'
e Toxic organic materials
D Acclimation
1 Tolerance to certain cations can be
increased by acclimation.
IV OPERATION
A Control
1 Control of the pH of the anaerobic pro-
cess depends on the maintenance of an
adequate bicarbonate buffer system.
A proper buffer system counteracts the
acidity of the carbon dioxide as well as
the acidity of the organic acids produced
2 Use of ORP(4'12)
(13)
3 Buswell lists factors that interfere
with digestion as:
a Sudden increase in feed
b Sudden change in pH of raw waste
c Sudden slug of inorganic material such
as Zn, Cu, CN or ' salts. "
d Sudden temperature change
B Digester Seeding
1 Value of adding digested sludge to start
digesters probably lies in production of
favorable environmental conditions such
as a suitable acid/alkalinity ratio as
much a,s in the numbers of bacteria
added.(14)
C Aids to Digestion
Distressed digestion can be attributed to
a number of factors, all of which directly
or indirectly alter the microbiological
environment. In certain cases, a more
favorable environment for these organisms
can be provided by restoring the favorable
environment by providing buffing alkalinity.
Lime has been used and reported in many
cases. Agricultural ammonia has been . .
found to be successful in certain applications.
Buswell^1^' suggests return of alkalinity in
the sludge from secondary digestion.
V SUMMARY
A Anaerobic digestion processes are capable
of treating greater amounts of organic
matter in less space than aerobic.
B Sludge accumulation is less because of the
greater influence of hydrolysis and lower
rate of growth under anaerobic conditions.
C Environmental control major factor in
effective operation.
14-3
-------
Anaerobic Process Principles
D Methane produced represents a useful fuel
and represents major BOD removal of
growth.
Table 1. Stimulatory and Inhibitory
Concentrations of Alkali and Alkaline-
Earth Cations'5^
Concentrations in mg/1
Moderately Strongly
Cation Stimulatory inhibitory inhibitory
Sodium
100-
¦200
3500-
-5500
8,
, 000
Potassium
200-
¦400
2500-
¦4500
12,
000
Calcium
100-
•200
2500-
¦4500
8,
000
Magnesium
75-
-150
1000-
-1500
3,
000
ACKNOWLEDGMENT
Certain portions of this outline contain
training material from a prior outline by
J. C. Dietz, Consultant, Clark, Dietz and
Associates, Urbana, Illinois
REFERENCES
1 Eckenfelder, W. W. and O'Connor, D. J.
Biological Waste Treatment, Pergamon
Press. New York. 1961.
2 Pohland, F. G. and Engstrom, R. J.
High-Rate Digestion Control. Proceed-
ings 19th Industrial Waste Conference.
Purdue University. 1964.
3 Imhoff, Karl and Fair, G. M. Sewage
Treatment. John Wiley and Sons, Inc.
New York. 1956.
4 Burbank, N, C. , Cookson, J. T.,
Goeppner, J. and Brooman, D. Isolation
and Identification of Anaerobic and Facul-
tative Bacteria Present in the Digestion
Process. Proceedings of the 19th
Industrial Waste Conference. Purdue
University. 1964.
5 McCarty, Perry L. Anaerobic Waste
Treatment Fundamentals. Public Works.
9:107-112, 10:123-126, 11 91-94,
12:95-99. 1964.
6 Cooke, William B. Fungi in Sludge
Digesters. Proc. 20th Ind. Waste
Conference. Purdue University.
Ext. Ser. 118. 6. 1965.
7 Speece, R. E. and McCarty, P L
Nutrient Requirements and Biological
Solids Accumulation in Anaerobic
Digestion. Proceedings of First
International Conference on Water
Pollution Research. Pergamon Press
London. 1964.
8 Pfeffer, J. T. and White, J. E. The Role
of Iron in Anaerobic Digestion. 19th
Industrial Waste Conference Bulletin.
Purdue University. Lafayette, Indiana.
1964.
9 Kugelman, I. J. and McCarty, P. L
Cation Toxicity and Stimulation in
Anaerobic Waste Treatment, II, Daily
Feed Studies. 19th Industrial Waste
Conference Bulletin. Purdue University.
Lafayette, Indiana. 1964.
10 Lawrence, A. W. , McCarty, P. L. and
Guerin, F. J. The Effects of Sulfides
on Anaerobic Treatment. Proceedings
19th Industrial Waste Conference.
Purdue University. 1964.
11 Rudolfs, Willem. Industrial Wastes.
Reinhold Publishing Company. 293-294.
New York. 1953.
12 Biological Treatment, Sewage and Industrial
Wastes. 2. Reinhold Publishing Company.
New York. 1958.
13 Buswell, A. M. Methane Fermentation.
Proceedings 19th Industrial Waste
Conference. Purdue University. 1964.
14 Heukelekian, H. and Heinemann, B. Sewage
and Industrial Wastes. 11. 436-444. 1939,
15 Cooper, J. F. , Hindin, E. and Dunstan,
G. H. Agricultural Ammonia for Stuck
Digesters. Proc. 20th Ind. Waste Conf.
Purdue University. Ext. Ser. 118. 126.
1965.
This outline was prepared by Paul F. Hallbach,
Chemist, National Training Center, Federal
Water Quality Administration, Cincinnati, OH
45226.
14-4
-------
Anaerobic Process Principles
Table 2
METHODS OF PREDICTING METHANE PRODUCTION*12*
Empirical Equation:
CH°.+ (n - a/4 - b/2) H90
nab I
(n/2 - a/8 + b/4) C02 + (n/2 + a/8 - b/4) CH4
1 Reactions not involving reduction of carbon dioxide
CHgCOOH C02 + CH4
4CH3OH 3CH4 + 2H20
2 Reduction of carbon dioxide without net decrease
4HCOOH CH4 + 3C02 + 2H20
4CH3CH2COOH + 2H20 7CH4 + 5C02
3 Reduction and net decrease of carbon dioxide
4H2 + C02 CH4 + 2H20
2CH3CH2OH + C02 CH4 + 2CH3COOH
2ch3(ch2)2ch2oh + co2— ch4 + 2ch3(ch2)2cooh
4CH3CHOHCH3 + C02 CH4 + 4CH3—CO—CH3 + 2HaO
2CH3(CH2)2COOH + C02 + 2HzO CH4 + 4CH3COOH
14-5
-------
ANAEROBIC INDUSTRIAL WASTE APPLICATIONS
INTRODUCTION
Use of Imhoff tanks and conventional di-
gestion processes for industrial wastes.
1 Economic considerations - large capital
investment.
2 Operational problems - lack of control
over fermentation.
3 Presently a part of industrial waste
treatment when domestic and industrial
wastes are treated together.
4 Conventional digestion used for certain
industrial waste treatment facilities.
Present developments and applications of
anaerobic waste treatment.
1 Anaerobic lagoons
2 Anaerobic contact process
3 Conventional process - simple anaerobic
digestion.
ANAEROBIC LAGOONS
Design Standards
1 State regulatory agencies in Illinois,
Iowa, Nebraska and Minnesota recom-
mend design loadings of 15 pounds BOD
per 1000 cubic feet of anaerobic
pond/ 1)
2 Requirements of regulatory agencies
for fill-and-draw lagoons - designed as
holding lagoons for discharge at high
stream flows but may operate as
anaerobic system.
3 Use of pilot lagoons to determine loading
rates, *2)
B Local Conditions Affecting Design
1 Geographic location a factor in loading
rates.
Higher temperatures enable increase
in loadings
2 Soil conditions
a Rock or high ground water
b Pervious soils where water pollution
may be possibility
c Construction of impervious lagoons
d Need for soil borings
3 Prevailing winds and closeness of
other facilities as odor problem
4 Receiving waters - Seasonal variation
of flow
5 Seasonal loadings to lagoons
C Construction Features
1 Inlet - Designed so as to provide rapid
mixing with existing digester mixture.
a Use of recirculation
2 Outlet - designed to prevent solids loss.
3 Cover for odor control and prevention
of heat loss.
a Natural cover built up by wastes
such as paunch manure in meat
plant wastes, Coerver.
b Styrofoam or similar cover such as
used by Mclntosrf4' ^ at American
Maize.
. MET. bi. 37a. 11. 66
15-1
-------
Anaerobic Industrial Waste Applications
4 Recirculation of, sludge to seed incoming
raw waste.
D Operation
1 Use of BOD or COD, and suspended
solids for determination of efficiencies.
2 Grease problems for specific wastes.
3 Determination of sludge accumulations.
4 Flow measurements of BOD values
used to determine waste loadings.
Ill ANAEROBIC CONTACT PROCESS
A Description of Process
1 The process involves the treatment of
a strong waste by mixing it with
anaerobic biological substrate and dis-
charging it after a limited time based
on a loading rate to a clarifier. Sludge
from the clarifier is returned to mix
with raw incoming waste to the digester
as shown on Figure 1. Provision for
degassing the mixed liquor is generally
provided before clarification to improve
sedimentation.
2 British type anaerobic process involves
anaerobic contact with pre-mixing
followed by sedimentation in a spiral
tank. (6)
B Design Standards
1 Loadings of from 0. 15 to 0.20 pounds
of BOD per cubic foot of digester per
day.
2 Suspended solids concentration up to
15, 000 mg/1 apparently provides for
success of operation.
3 Process similar to the aerobic activated
sludge process.
C Local Conditions Affecting Design
1 Small area requirement as compared
to anaerobic lagoons
2 Temperature control by heat exchanger
3 Close control of process
D Construction Features and Operation
1 Use of flow equalization (Figure 2)
2 Need for digester mixing
3 Corrosion - resistent materials for
gas piping, degasifier and digester
4 Degasifier required prior to sludge
settling.
5 Separators or settling tanks required
6 Sludge return from separator to raw
waste line to digester
7 Flow measuring and recording equipment
8 Need for anaerobic contact effluent
treatment
IV SIMPLE ANAEROBIC DIGESTION
A Description of Process
1 In this process, wastes are digested
at controlled temperatures and the
effluent drawn off at certain levels
in the digester.
a Conventional sludge digestion -
loadings of 0. 03 - 0.04 lbs. volatile
solids per cubic foot per day.
b High rate sludge digestion - 0. 18
lbs. volatile solids per cubic foot
per day.
B Design Features (Figure 3)
1 Gas collection
2 Digester heating
3 Sludge removal
4 Supernatant removal and disposal
15-2
-------
Anaerobic Industrial Waste Applications
V APPLICATIONS
A Anaerobic Lagoons
1 Meat wastes
(7)
a Moultrie, Georgia, treating a meat
packing waste in an anaerobic lagoon
14 feet deep and 1.4 acres in surface
area, followed by an aerobic lagoon
with atotal area of 19. 2 acres and a
depthof 3 feet. The dententiontime is
6 days in the anaerobic pond and 19 days
in t he ae r obic pond. T he BOD load mg
is about 0. 014 lb/day/cu. ft. in the an-
aerobic stage, and 50 lbs/day/acre in
the aerobic stage, with an overall BOD
loading of 325 lbs/day/acre. Sludge is
recirculated in the anaerobic lagoon
and effluent is recirculated in the an-
aerobic lagoon. The BOD of the raw
waste averaged 1, 100mg/l, and the
effluent averaged 67 mg/1 over a 4-
year period.
b Edmonton, Ontario^anaerobic
lagoons show removal as follows:
suspended solids, 75 per cent, BOD,
70 per cent; and grease, 79 per cent.
c Union City, Tennessee^ lagoon
provided BOD, grease and suspended
solids removals of over 90 per cent.
(9)
d Luverne, Minnesota lagoons showed
removals of 58 per cent BOD at load-
ings of 16 lbs. BOD per 1000 cubic
feet per day.
(3)
e Coerver describes the use of
shallow anaerobic lagoons for packing
house waste treatment at three
installations in Louisiana. Average
BOD removals are 92.4 per cent.
With an aerobic lagoon for polishing,
overall BOD removals of 98 per cent
are secured.
2 Corn wet milling wastes
(4 5)
a Roby, Indiana ' American Maize
Products Company uses 2.4 acre
anaerobic lagoon to treat 600, 000
gpd of 2260 mg/1 BOD, temperature
95°F waste. Loadings of 14 lbs. per
1000 cubic feet with 90 per cent
BOD removal. Uses styrofoam
covers for temperature control.
3 Chemical and fermentation
a Terre Haute, Indiana^10^ installation
removing 60 to 80 per cent BOD
removal on raw waste of 10, 000
mg/1 BOD and 30, 000 mg/1 suspend-
ed solids at 450 lbs per acre at 4
foot depth and 220 day retention.
4 Soy bean wastes
a Taylorville, Illinois^, Allied
Mills uses two-level 3.2 mg lagoon
with 10 foot normal depth, 12 foot
high level depth. (Figure 4)
5 Poultry manure wastes
The use of anaerobic lagoons^ for
poultry manure wastes in California
has been successful with no observed
problems.
6 Livestock manure
Livestock manure anaerobic lagoons
can be operated successfully with proper
design and control. The need for such
waste treatment will probably increase
installations in this particular area' '
B Anaerobic Contact Process
1 Meat wastes
a Wilson and Co. plant at Albert Lea,
Minnesota ^ with
digester loadings of 0. 16 to 0.20
lbs. per cubic foot per day with 90
to 94 per cent BOD removal. Raw
waste strengths of 1300 to 1600 mg/1
BOD. Sludge concentrations in the
mixed liquor from 7000 to 10, 000
mg/1. Uses vacuum degasification.
(1)
b Agar Plant at Momence, Illinois
uses vacuum degassification results
in 85 to 92 per cent BOD removal
on raw waste strengths of 1500 to
2000 mg/1 BOD. Waste flow of
0. 4 to 0.6 mgd.
15-3
-------
Anaerobic Industrial Waste Applications
c Austin, Minnesota plant uses aeration
for gas removal prior to sludge
separation. At loading of 0. 059
pounds per cubic foot, 96 per cent
BOD removal achieved on wastes
of 1400 mg/1 BOD.<6)
C Conventional Process
1 Yeast plants^
a Standard Brands, Pekin, Illinois.
Six digesters in these stages handling
225, 000 gallons per day of 10, 000
mg/1 BOD waste with 10 day deten-
tion. Plant built in 1940. Loaded
at 0. 108 pounds per cubic foot.
b Crystal Lake Yeast Co., Crystal
Lake, Illinois. Two stage digestion
with four days' detention. Raw
waste BOD 5000 mg/1, anaerobic
effluent 1500 mg/1.
(fi)
2 Grain waste plants
a Peoria, Illinois. Butanol acetone
wastes with raw BOD of 17, 000
mg/1 loaded at 0. 114 pounds per
cubic foot. With 10 day detention
effluent of 2400 mg/1 BOD.
b Carthage, Ohio. Pilot plant at dis-
tillery treated 16, 000 mg/1 BOD
wastes at 0. 143 pounds per cubic
foot loading with effluent of 1600
mg/1 at 14 days' detention.
3 Cane sugar plants
Pilot plant studies indicate that the
waste from cane sugar factories can be
treated effectively by anaerobic diges-
tion followed by stabilization in an oxi-
dation pond. BOD reductions in the
anaerobic portion of the process ranged
from 60 to 70 percent with 70 percent re-
ductions achieved in two days detention
time with a heated digester.* '
4 Antibiotic wastes
Antibiotic-containing waste slurries
were reported to be treated success-
fully by anaerobic treatment. ^
VI USE OF PILOT PLANT STUDIES
A The use of pilot plant studies on a bench
or larger scale provides for better design.
1 Studies indicate lack of nutrients and/
or presence of toxic materials.
2 Cost of pilot studies are relatively small
compared to the total expenditure for the
installation and can be offset in many
cases by increased design loadings re-
sulting in lower first costs of treatment
units.
B Effluent from pilot studies can be used for
evaluation of treatment required following
the anaerobic process.
VII SUMMARY
A Economics
1 Anaerobic lagoons and anaerobic contact
process provides excellent and economical
means of treating certain high strength
wastes.
2 Cost figures for packing house wastes
are shown on Figures 5 and 6. Costs
were determined for 0.5, 1.5 and 2.5
mgd flow with BOD loadings of 5, 000,
12, 000 and 15, 000 lbs per day. Land
cost for lagoons were $500 per acre.
Insurance, taxes, depreciation, power,
labor and other items were included in
the annual cost comparison. Interest
was taken at five per cent.
3 Choice between anaerobic contact or
anaerobic lagoons can generally be
determined by cost studies.
B Treatment of Anaerobic Effluent
1 The effluent from the anaerobic con-
tact process or anaerobic lagoons can
be treated by conventional aerobic
processes.
2 Odor is not a problem in properly
designed system.
15-4
-------
Anaerobic Industrial Waste Applications
C Degree of Treatment
1 Anaerobic contact and anaerobic
lagoons can reduce waste BOD by
90 per cent or greater.
Degree of treatment depends on loading
rates, temperature and other factors.
15-5
-------
CD
VACUUM PUMP
DEGASIFIER
INF. ELEV. 125.67
MAX. WATER
SURFACE 111.0
MAX. WATER—>
SURFACE 104.91
HOLDING
TANK
PUMP
STATION
WATER SURFACE
93.10
SEPARATOR
TO POLISHING
TREATMENT
WET
WELL
RAW WASTE
DIGESTER
I
Z_"
j
RETURN SLUDGE
ANAEROBIC CONTACT PROCESS
Figure 1
-------
Anaerobic Industrial Waste Applications
400-
o 300-
I2M
(E 200H
£
03
u 100-
o
6AM
I2N
6PM
12 M
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I
a:
bj
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Z3
s
TOO
IZN
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ISM
Figure 2
7
-------
Anaerobic Industrial Waste Applications
SUPERNATANT.
DRAIN
DRAW-OFF BOX
DIGESTED SLUDGE
DRAW-OFF
CONCRETE STOPS FOR
FLOATING COVER
CONCRETE
PIPE SUPPORT
PLAN
FLOATING
GAS DOME
BERM
7W71
GAS WITHDRAW
LINE
RECIRCULATION
SUCTION
DIGESTED SLUDGE
DRAW-OFF
SUPERNATANT
W-OFF
SLUDGE
RECIR CULA
TIOH
H-alternate
BRICK
FACING
PIPE SUPPORT
SLUDGE DIGESTER
8
Figure 3
-------
ANAEROBIC LAGOON
AEROBIC LAGOON
-TOP OFBERM ELEV.= II0.0
ANAEROBIC LAGOON
OVERFLOW
WATER SURFACE
*
::::::::::
iiiiiil
iiiiiiii:
:::::::::::
::::!!
:::::::
:::::
:::::::
:::::::::::
::::
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EFFLUENT ELEV»I0I0
ROI
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;i;!*-8"INFLUENT TO AEROBIC
•J:::::::::::::::::*:::::::::::::::::::::;*;;
18 INFLUENT TO ANAEROBIC
LAGOON ELEV =93.0
ANAEROBIC-AEROBIC LAGOONS
Figure 4
-------
Anaerobic Industrial Waste Applications
FIRST COST
INCLUDING LAND COST
ipoopoo
CO
< 800,000
O 600,000
CO
400P00
0.5
2.0
2.5
3.0
CAPACITY-MGD
10
Figure 5
-------
Anaerobic Industrial Waste Applications
ANNUAL COST COMPARISON
INCLUDES FIXED AND OPERATING COST
CO
IOO.OOQ
50000
25
30
0.5
2.0
1.0
CAPACITY - MOD
Figure 6
11
-------
Anaerobic Industrial Waste Applications
REFERENCES
1 Dietz, J. C., Clmebell, P. W., and Strub,
A. L. Design Considerations for An-
aerobic Contact Systems. Jour. Water
Poll. Control Fed. 38, 4, 517. April
1966.
2 Dietz, J. C., Clinebell, P. W., and Strub,
A. L. Anaerobic Pre-Treatment of
Packing House Wastes. Fifth Annual
Sanitary and Water Resources Engineer-
ing Conference, Vanderbilt University
(In Press).
3 Coerver, James G. Anaerobic and Aerobic
Ponds for Packing-House Waste Treat-
ment m Louisiana. Proceedings of the
19th Industrial Waste Conference.
Purdue University. 1964.
4 Mcintosh, G.H., and McGeorge, G. G.
Lagoon Treatment of Corn Wet Milling
Wastes. Presented at Indiana Water
Pollution Control Association Conference.
November, 1962.
5 Mcintosh, G.H., and McGeorge, G. G.
Keep Waste Water Warm with Floating
Plastic-Foam Blanket for Efficient Year-
Round Lagoon Operation. Food Pro-
cessing, pp 82-86. January, 1964.
6 Steffen, A. J. Anaerobic Industrial Waste
Applications. Presented at Training
Program, SEC. 1964.
7 Sollo, F. W. Pond Treatment of Meat
Packing Plant Wastes. Presented at
15th Purdue Industrial Waste Conference.
May, 1960.
8 Stanley, Donald R. Treatment of Meat
Packing Plant Wastes in Anaerobic and
Aerobic Lagoons. Presented at 12th
Ontario Industrial Waste Conference.
June, 1965.
9 Rollag, D.A., and Dornbush, J. N. Design
and Performance Evaluation of an
Anaerobic Stabilization Pond System
for Meat Processing Wastes. Pre-
sented at 38th Annual Meeting, Central
States Water Pollution Control Associ-
ation, Albert Lea, Minnesota. June,
1965,
10 Howe, David O., Dr, Miller, Archie,
P., Etzel, James E., Dr. Anaerobic
Lagooning - A New Approach to Treat-
ment of Industrial Wastes. Proceedings
of the 18th Annual Industrial Waste
Conference, Purdue University, Series
115, pp 233-242. 1963.
11 Cooper, R. C., Oswald, W. J., and Bronson,
J. C. Treatment of Organic Industrial
Wastes by Lagooning. Proc. 20th Ind.
Waste Conf., Purdue Univ. Ext. Ser.
118, 351. 1965.
12 Hart, S. A., and Turner, M. E. Lagoons
for Livestock Manure. Journ. Water
Poll. Control Fed. 37, 11, 1578. Nov.
1965.
13 Schroepfer, G.J., Fullen, W. J., Johnston,
A.S. , Ziemke, N. R., and Anderson, J. J.
The Anaerobic Contact Process as
Applied to Packinghouse Wastes. Sewage
and Industrial Wastes, Vol.27, No. 4.
pp 461-486. 1955
14 Steffen, A. J. Full-Scale Modified Di-
gestion of Meat Packing Wastes.
Sewage and Industrial Wastes. Vol.
27, No. 12, pp 1364-1368. December,
1955.
15 Steffen, A. J., and Bedker, M. Separation
of Solids in the Anaerobic Contact Pro-
cess. Public Works, Vol. 91, No. 7.
pp 100-102. July, 1960.
16 Steffen, A. J., and Bedker, M. Full
Scale Anaerobic Contact Treatment
Plant for Meat Packing Wastes. 16th
Purdue Industrial Waste Conference.
1961.
17 Steffen, A. J. Stabilization Ponds for
Meat Packing Wastes. Journal Water
Pollution Control Federation, Vol. 35,
No. 4, pp 440-444. April, 1963.
15-12
-------
Anaerobic Industrial Waste Applications
18 Bhaskaran, T. R., and Chakrabarty, R.N.
Pilot Plant for Treatment of Cane-Sugar
Wastes. Jour. Water Poll. Control Fed.
38, 7, 1160. July 1966.
19 Purice, V. Methane-Production Fermenta-
tion of Slurries in Residual Waters
Effected in the Waste-Recovery Station
of the Antibiotics Plant-Iasi. Chem. Abs
63, 2737. 1965.
This outline was prepared by J. C. Dietz,
Consultant, Clark, Dietz, and A ssociates,
Urbana, Illinois.
15-13
-------
-------
FACTORS AFFECTING DIGESTER EFFICIENCY
I INTRODUCTION
A A previous outline by W. L. Carter described
representative equipment for anaerobic
digestion and related functions. This out-
line reviews some of the factors pertaining
to operation of anaerobic digesters.
B Anaerobic digestion is a biological process
operating in the absence of dissolved oxygen
in which sludge solids are partially degraded
to form gaseous, liquid, or solid residues
of greater stability than that prior to
digestion.
1 The gaseous products include methane,
carbon dioxide and smaller proportions
of other components some of which are
highly malodorous.
2 Liquid residues include ammonia, free
fatty acids, soluble mineral or organic
components formed in process as inter-
mediates or in side reactions. The
liquid fraction usually contains associated
solids in a finely divided state.
3 Solid residues remaining characteristically
are increased m stability and disposability
because-
a The more unstable components are
likely to be part of the gas, or eluted
from the solid residues in discharged
liquid.
b Digested solids are likely to have a
higher solids concentration and occupy
less volume than before processing.
c Properly digested sludge solids are
more readily separated from remaining
water; i. e., they are improved in
drainability, filterability and driability.
II Anaerobic digestion is a common process
occurring wherever and whenever organic
refuse accumulates to a point where dissolved
oxygen penetration is insufficient to satisfy
aerobic requirements.
A Partial anaerobic digestion occurs m both
natural and engineered facilities such as'
1 Refuse dumps may degrade via aerobic
action at the surface but undergo
anaerobic degradation in the interior if
the conditions, amount and nature of the
refuse are suitable.
2 Pooled areas (such as swamps, pot holes,
impoundments) in surface water may
permit accumulation of benthic deposits,
miscellaneous organic residues and
other materials in amounts exceeding
dissolved oxygen supply.
3 Septic tanks, Imhoff tanks, cesspools,
and natural or engineered basins for
discharge of water carried wastes of
human activities generally are
anaerobic.
4 Engineered facilities such as those
described previously including
a Conventional digesters
b High rate digesters
c Anaerobic contact processes
d Anaerobic lagoons
B Anaerobic degradation is limited by the
biological, chemical, and physical factors
common to natural processes. Available
energy, temperature, acid-alkalinity
relationship, mixing, time, and seeding
are major variables controlling the
progress of anaerobic digestion.
SE. AN. pp. 1. 11. 68
16-1
-------
Factors Affecting Digester Efficiency
III Control of digestion presupposes recog-
nition of certain generalities involved in
natural processes. Waste treatment control
depends upon selecting those conditions that
enhance the probability that a given operation
will be favored and maintained within
acceptable limits for achieving acceptable
treatment.
A Biological degradation includes aerobic
and anaerobic processes that are so
closely interrelated that it is frequently
difficult to distinguish among them.
1 Aerobic degradation is characterized by
conditions in which dissolved oxygen
is present in excess in the water mass.
2 Facultative degradation is characterized
by low dissolved oxygen levels or by
conditions that involve alternate periods
of dissolved oxygen excess or deficiency.
3 Anaerobic degradation is characterized
by a gross deficiency of dissolved oxygen.
Bound oxygen from sulfates, carbonates
or other sources must be released in
process to satisfy the oxygen require-
ments of the anaerobic system.
B Treatment operations involve all of the
three stages of degradation listed under
III A.
1 III A 1 is predominant in terminal
stabilization of wastewaters. Ill A 2
is predominant in most wastewater
treatment operations such as activated
sludge, trickling filtration or lagoons.
Ill A 3 is predominant when organic
solids degrade to acid and gas formation.
2 It must be recognized that sludges
obtained from primary or secondary
clarifiers are likely to be at some
transition stage from III A 2 to 3 before
entering anaerobic digestion. Control
of operation includes techniques designed
to smooth progress of the transition.
C The input solids for anaerobic digestion
include complex organic materials such
as preformed proteinacious, fatty, or
carbohydrate residues from animal or
plant sources. Cell mass, of bacterial,
animal, or plant origin commonly is a
large fraction of the material to be digested.
It is usually associated with more inert
materials of organic or inorganic origin.
1 The preformed material of high
molecular weight commonly undergoes
enzymatic hydrolysis as a first step in
degradation, 1. e. proteins are split to
form peptides, the peptides are degraded
to amino acids, the amino acids are
deaminated to form free fatty acids and
ammonia.
2 The resulting free fatty acids may then
be converted to methane and CO„ or
other degradation products. Spfitting
and gasification both are essential to
the anaerobic process.
3 Hydrolytic splitting is common to
aerobic and anaerobic degradation.
More rapid cell growth under aerobic
conditions tends to resynthesize
smaller molecules that tend to remain
for later treatment after anaerobic
degradation.
4 The splitting process (hydrolysis or
acid formation) is rapid compared to
gasification and alkalinity formation in
anaerobic digestion. Digestion control
includes holding sufficient older alkaline
sludge to prevent acidification from
predominating upon addition of new feed.
Digestion is unsatisfactory under acid
conditions.
5 Maintenance of alkalinity is difficult to
control because this stage of digester
operations is characterized by organisms
that are readily upset by an unfavorable
environment and have a low growth rate
so that it requires extended time to
reestablish an effective population after
an upset. Further, acid production
occurs so readily and rapidly that there
are many opportunities for production
of a sour or malfunctioning digester.
16-2
-------
t
Factors Affecting Digester Efficiency
IV Section II B listed several factors
influencing digester operation efficiency.
This section considers some of the more
important control limits and techniques.
A Toxic effects of mineral acids, inorganic
and organic toxic agents, may disrupt any
biological system. The alkaline or
gasification stage of anaerobic digestion
is more sensitive to toxic agents than most
biological processes and requires longer
time to recover from toxic effects. Toxic
limits of various materials are included
in references too numerous to include
herein.
B Available energy contained in feed sludge
must be sufficient to provide net energy
for metabolism and product formation after
expenditure of energy for release of oxygen
from sulfates, carbonates, etc. Anaerobic
digestion conversions are limited to those
for high energy foods and tends to decrease
in conversion efficiency as partial digestion
proceeds.
C Temperature has a two-fold effect upon
digestion. There appears to be a vaguely
defined minimum temperature below which
gasification is limited severely and the
temperature variation permissible within
the optimum temperature has narrow
limits to maintain consistant digestion.
1 Septic or Imhoff tanks and unheated
digesters maintain acid production and
liquefaction but commonly show a low
rate gas production at temperatures of
about 20OC (68° F) or less. Very long
detention time (6-12 mo.) may be
required for conversion other than
concentration of solids and elution of
soluble or colloidal solids at the lower
temperatures.
2 Conventional digestion temperatures of
25°C to 350 C (780 F to 95°F) favors
good gasification in 20 to 30 days
providing other conditions are acceptable.
3 Higher digestion temperatures may
favor more rapid conversion to gas,
more complete gasification or more
throughput per unit of volume. The
thermophillic range of digestion from
490C to 56° C (120OF to 135o F) has
had limited use for special effects or
types of waste. It is characterized by
poor quality supernatants.
4 Digestion rate may be adversely
affected by a temperature change of
20 to 5°C (4o to 9of). Temperature
changes that occur within 1 to 3 hours
may disrupt operation, whereas the
same absolute change over a period of
1 to 3 days may not show noticeable
effects. Addition of large volumes of
cold sludge is a common cause of the
rapid temperature changes during
digestion (such as after an intensive
rain).
D Acid-alkalinity balance is interrelated
with all major control variables and is a
difficult but essential control.
1 pH control is an "after the fact" means
of controlling digester operation.
Acid-alkalinity balance has progressed
too far by the time that a pH change
occurs.
2 New feeds tend to produce a release of
acid products that must be buffered or
neutralized by alkalinity produced in
later stages of digestion. If a sufficient
quantity of older sludge is not present
in the mixture, the digester becomes
acid (or sour) and digestion fails.
3 Withdrawal of too much old sludge for
disposal, addition of excessive quantities
of fresh sludge, such as after a ram,
chronic overloads, addition and
retention of low solids concentrations
in the digester favor acid or sour
digesters.
4 Determination of volatile acids and
alkalinity in the digester are essential
for consistent control. Experience
shows that a volatile acid equivalent
more than 1/2 of the alkalinity
expressed as calcium carbonate calls
for corrective action to prevent upset.
Buffer capacity diminishes rapidly with
more acid conditions.
16-3
-------
Factors Affecting Digester Efficiency
5 Absolute values for acid or alkalinity
are less important than the trend or
change of values in process and the
ratio of acid with respect to alkalinity.
6 Conventional digestion operation
commonly is considered effective at
volatile acids below 2000 mg/land
alkalinities of 3000 to 5000 mg/1.
High acid content tends to reduce
alkalinity which may result in unfavorable
pH response when the acid content
exceeds equivalent alkalinity.
E Seeding is an essential in digester startup
and in maintaining digestion effectiveness
from an organism and an acid-alkalinity
standpoint.
1 Organisms capable of gasification are
slow growing. It would require 1 to 3
months of operation starting from a
wastewater filled digester to accumulate
enough old sludge to permit conventional
loading. If the fresh feed is increased
too rapidly, acid production tends to
exceed alkalinity available in the old
sludge and the process fails. Acid
alkalinity balance must be carefully
checked to estimate permissible loading.
2 Addition of a significant volume
(3000 to 10, 000 gallons) of concentrated
solids from an established digester
materially shortens startup time,
accumulation of sludge solids, and
permissible loading rates during
startup.
3 Organisms are mainly associated with
the sludge solids. Supernatants or other
low solids mixtures generally are not
effective for seeding or alkalinity
control.
F Mixing is one of the most common
difficulties in digester operation.
Effective gasification provides fairly good
vertical mixing but mixing is most needed
when gasification isn't proceeding normally
such as after startup or upset.
1 Digestion tends to produce segregation
of phases into a bottom sludge con-
taining most of the active organisms,
a scum zone at the top containing
grease, oils, and undigested solids
more or less bound together by fibrous
materials and a liquid fraction between
the scum and solids zones. The three
layers must be mixed to achieve
effective digestion.
2 Older digestion units commonly
depended upon recirculation of
supernatant in a circular horizontal
pattern with casual attention to vertical
mixing.
3 Introduction of feed above scum levels,
floating covers to submerge scum, and
bottom to top circulation helped
digestion providing sufficient pump
capacity and working time was used.
In many cases pump capacity was
insufficient to circulate more than 1/2
of the contents of the tank in any 24 hour
period of continuous use. Obviously,
this is not highly effective mixmg.
4 Gas recirculation appears to be gaining
m popularity for improving digester
mixing and concurrent operating
efficiency.
5 Propellers in vertical draft tubes also
are effective until abrasion destroys
impeller efficiency.
6 Effective mixing can greatly extend
capacity of any digester by insuring
good contact of sludge and feed, con-
trolling heat uniformity, and preventing
local accumulation of scum, grit, or
grease. Good mixing is an essential
for primary or high rate digesters.
G Loading is closely related to acid-
alkalinity balance. A new feed may be
expected to result in a rapid rise in
digester acidity. Good digestion will
continue if there is enough old sludge
containing alkalinity to overbalance acid
production (assuming intimate mixing).
16-4
-------
Factors Affecting Digester Efficiency
1 Precautions in adding new feed at frequent
intervals in small amounts helps to
maintain uniform operation and suitable
ratios of acid and alkalinity needed to
permit organism activity.
2 Rapid changes in loading are to be
avoided if possible. If unusual slug
discharges are unavoidable, such as
following a rain, it is advisable to
balance excessive amounts of new feed
with larger amounts of older sludge
returned from secondary digestion to
reduce the ratio of new volatile solids
added per unit of digester volatile solids.
3 Conventional digestion usually means
addition of 2 to 4% new volatile solids
per day. High rate digestion may
include from 5 to 20% of new solids per
day. Some reports of higher loading
ratios are given. The basic loading
criteria refers to a ratio of new volatile
solids per unit of volatile solids already
present in the digester.
4 The common load criteria of pounds of
BOD per day is a convenient expression
of input related to volatile solids mput
and assuming the presence of an adequate
amount of old solids to satisfy the load
ratio criteria indicated in IV G 3.
5 Detention time likewise is related to a
load ratio criteria, i.e., 4% new solids
per day implies that it will require
about 25 days to replace the entire tank
contents and that there was 24 days
accumulation of old material in the tank.
This is not strictly true as part of the
volatile solids was removed as a gas
and part was removed as eluate
(supernatant) or waste sludge. Detention
periods of as low as 3 1/2 days have
been reported for high rate digestion
(load ratios exceeding 0. 2/ 1. 0 VS
basis). Continuous vigorous mixing
is essential to approach this type of
operation. Ten days is about the limit
for applied use.
6 It is imperative that some acceptable
ratio of new solids to pre-existing
digester solids be maintained, however
it is expressed. Gross old sludge
removal or new sludge addition tend to
upset the acceptable ratio found for a
given operation.
A CKNOWLEDGMENT:
This outline contains certain materials
available from previous outlines by
J.C. Dietz and L.T. Hagerty.
This outline was prepared by F. J. Ludzack,
Chemist, National Training Center, FWQA
Cincinnati, OH 45226.
16-5
-------
aerobic digestion
I INTRODUCTION
i
The digestion process, that is the decom-
position of organic matter to a non-putrescible
and moffensive state, can occur under either
anaerobic or aerobic conditions. It is the
purpose of this discussion to present the
general concepts and to briefly outline the
various aerobic digestion methods.
H
y:
R-
C —fH
I
H
-2H
n+2H
H
\
N
II
R C
I
H
II MECHANISMS OF AEROBIC DIGESTION
In aerobic digestion, complex organic materials
such as fats, proteins, and carbohydrates are
decomposed to form simpler products.
The products of hydrolysis and oxidation
resulting from aerobic digestion, and the
cyclic nature of the component elements
(carbon, nitrogen, and sulfur) are shown in
Figure 1. Comparison with the cycle for
anaerobic digestion (Figure 2) reveals signif-
icant differences in the nature of the
decomposition products.
Oxidation is defined as the removal of hydrogen,
addition of oxygen, or other reaction making
the oxidized item more electropositive. The
removal of hydrogen is a common first step in
decomposition of organic matter as illustrated.
f H~ ~H~l
TT
R—C C—H —r—C= C H
I I I |
H H H H
The hydrogen atoms removed combine with
oxygen, carbon, nitrogen, or sulfur.
Aerobic bacteria utilize oxygen as the
hydrogen acceptor. Anaerobic bacteria use
"chemically bound oxygen, " carbon, nitrogen,
or sulfur as the hydrogen acceptor.
Facultative bacteria may use both of these
but in any case will use the hydrogen acceptor
yielding the most energy.
Hydrogen removal follows a definite pattern
and is brought about by the coenzymes DPN
or TPN. DPN and TPN take up one hydrogen
ion and two electrons leaving one free
hydrogen ion.
In aerobic microorganisms, DPN is
regenerated by flavin adenosine dinucleotide
(FAD). The reaction being-
DPNH2 + FAD DPN + FADH2
FADHg is regenerated with oxygen to form
water.
2FADH2 + 02 2FAD + 2H20
/ \
OH \
' K\
R— C-^-H
H
-2H.
S+2H
0
R C
1
H
III AEROBIC ACTIVITY
It is necessary to have a supply of the proper
types of microorganisms, suitable food
materials, an oxygen source, and an environ-
ment conducive to growth and reproduction.
A Microorganisms
Decomposition of organic waste requires
a community consisting of many kinds of
organisms:
SE.AE. 2. 11. 68
17-1
-------
Aerobic Digestion
Dead
Organic
Matter
Living
Animal Matter
Proteins
Fats
aS&
roA
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Initial
Products of
Decomposition
1. Ammonia
nitrogen
2. Carbon dioxide
^3. Hydrogen
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Reservoir of
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Final
Products of
Decomposition
1. Nitrate nitrogen
2. Carbon dioxide
l3. Sulfates
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itermediate
Products of
Decomposition
1. Nitrite nitrogen]
2. Carbon dioxidej
Sulfur
FIGURE 1. Cycle of nitrogen, carbon, and sulfur in aerobic decomposition.
17-2
-------
Aerobic Digestion
oNe
6e"
Dead
Organic
Matter
1. Nitrogenous
t2. Carbonaceous
Sulfurous
'Afc
Living
Animal Matter
Proteins
Fats
v
*
i-H
cd
6
a
<
initial
Products of
Decomposition
[1. and 2. Organic
|acids, acid carbon-
ites, and carbon
^dioxide,
3. Hydrogen
CK
&J
Reservoir
of Oxygen,
Nitrogen and
Carbon Dioxide in
Air and Water
.o®
Sulfide
6®c
Living Plant
Matter
Proteins
Carbohydrates
Fats
03
V
CO
cd
O
e
o
ao
o
a
6
o
o
0)
73
A>,
a
o
a.
6
o
u
V
Q
Intermediate
Products of
Decomposition
and 2. Ammonia
utrogen, acid
^carbonates, and
kcarbon dioxide
3. Sulfides
inal
Products of
Decomposition
. and 2. Ammonia
nitrogen, humus,
carbon dioxide, and
methane
3. Sulfides
FIGURE 2. Cycle of nitrogen, carbon, and sulfur in anaerobic decomposition
17-3
-------
1
Bacteria
C Oxygen Source
2 Molds
3 Yeasts
4 Algae
5 Protozoa
6 Rotifera
7 Worm and insect larvae
B Food Materials
Nearly all organic wastes may serve as
food supply for the community. Some
exceptions may be organic pesticides,
hydrocarbons, and ethers. It has been
shown, however, that even highly toxic
materials, such as phenols, can be used
as food if the community is acclimated to
the waste.
The oxygen source is generally the
atmosphere but the method of introducing
this oxygen into the waste stream will
vary, depending upon the method of
treatment.
The oxygen budget (Figure 3) illustrates
the factors which affect the dissolved
oxygen concentration in a water mass.
In the case of aerobic digestion of organic
wastes, reaeration is the most significant
means of supplying the required oxygen.
In natural streams, lakes, ponds, and
bays photosynthesis can become a
significant source of dissolved oxygen
during daylight hours.
D The Environment
Important environmental factors include:
temperature, pH, organic waste concen-
tration, presence of toxic substances, and
substrate for biological growth.
FIGURE 3
REAERATION
LOSS FROM
SUP ER - SA TU RA TION
ADVECTIVE
GAINS
PHOTOSYNTHESIS
RESPIRATION
ADVECTIVE
REDUCTION
C.O. D.
„ inssps
B.O.D.
DIFFUSION INTO
BOTTOM MUDS
DISSOLVED OXYGEN
OF A
WATER MASS
17-4
-------
Aerobic Digestion
1 Temperature has an effect on the rate
of biological activity as well as being
a determining factor in the types of
organisms which will thrive. The
range at which mesophilic microorganisms
thrive is up to 110OF; the thermophilic
range extends above 110°F with optimum
activity at 130°F. Activity decreases
rapidly below about 10oc but is detectable
at loc.
2 pH
A pH range of 6. 0 to 8. 5 is considered
desirable.
3 Concentration of waste
Abnormally high concentrations of
wastes may be intolerable over an
extended period. The result of overload
is usually the development of anaerobic
conditions.
4 Toxic materials
Very dilute concentrations of toxic
materials can usually be tolerated by
at least some of the organisms living
in the community. As these types
become prevalent it is not uncommon
to find that they decompose the toxic
material.
5 Substrate
Substrates used to provide suitable
environmental conditions for develop-
ment of a community of microorganisms
vary with the type of treatment facility.
In the trickling filter, the substrate is
the rock or filter media; in the activated
sludge plant the substrate is the floe
which in itself is a colony of micro-
organisms.
IV AEROBIC TREATMENT METHODS
A Activated Sludge
Activated sludge is a process into which
sufficient air is added to maintain aerobic
conditions during the treatment process.
The culture substrate is composed of
small floe particles of decomposing
organic matter and bacteria.
B Trickling Filter
The trickling filter maintains aerobic
conditions through counter-current flow
of air upward through the filter stone as
the waste trickles downward over the
bacterial colonies attached to the filter
media.
C Stabilization Pond
Aerobic conditions in a stabilization pond
depend upon reaeration through the surface,
wind action in both dissolving oxygen into
the water mass and for mixing. Photo-
synthesis may be important in daylight
hours as a source of dissolved oxygen.
V SUMMARY
A The final products of aerobic digestion are:
1 Carbon dioxide
2 Nitrate nitrogen
3 Sulfates
4 Water
5 Residues of relatively stable substances
B Decomposition proceeds by the removal
of hydrogen from the organic wastes.
This hydrogen may combine with
1 Oxygen to form water
2 Nitrogen to form ammonia
3 Carbon to form methane
4 Sulfur to form hydrogen sulfide
17-5
-------
Aerobic Digestion
In aerobic digestion, the predominate
hydrogen acceptor is oxygen, with nitrogen,
carbon, and sulfur proceeding to form
NO". COg, and SC>4= during decomposition
of organic matter. Hydrogen acceptors
during anaerobic degradation include carbon
to form methane and oxygen to form water.
C A suitable environment must be provided to
stimulate the growth and reproduction of
a biological community. Such an environ-
ment may be provided for treatment of
organic wastes in:
1 A trickling filter
2 Activated sludge
3 Stabilization ponds
2 Fair, G. M. and Geyer, J. C., Water
Supply and Waste-Water Disposal,
John Wiley &. Sons, New York, (1966).
3 Gurnham, C, F., Principles of Industrial
Waste Treatment, John Wiley &. Sons,
New York, (1955).
4 McKinney, R.E., Microbiology for
Sanitary Engineers, McGraw-Hill,
New York, (1962).
5 Rich, L. G., Unit Processes of Sanitary
Engineering, John Wiley & Sons,
New York, (1963).
REFERENCES
1 Babbitt, H. E., Sewerage and Sewage This outline was prepared by L. J. Nielson,
Treatment, John Wiley & Sons, New York, Sanitary Engineer, FWPCA Training
(1953). Activities, PNWL,
17-6
-------
ACTIVATED SLUDGE WASTE TREATMENT PROCESS
VARIATIONS AND MODIFICATIONS
I INTRODUCTION
A In practice there are three ranges of food-
to-microorganism (F/M) ratios where the
resultant activated sludge physical quality
permit successful continuous plant operation
with a minimum of problems. The higher
loading range is designated high rate, the
intermediate range is conventional, and
the lowest loading range is extended
aeration. The fourth basic process
variation does not require sludge separation
for recycle. It operates at the highest
loading range and is designated dispersed
growth. The characteristics of these
process variations are shown graphically
in Figure 1.
B While there are four basic process variations
to be considered in activated sludge waste
treatment, there are many modifications
that have been adapted by the design
engineer since the first activated sludge
waste treatment plant was constructed in
the United States about 1920. The purpose
of this outline will be to consider these
major modifications and their advantages
or limitations. ,
Endogeneous Phase
Log Growth
Declining
Growth
.Microorganisms
"1*14
/f Conventional
it
High >
Kate
Dispersed'
Growth/
Extended Aeration
Food Remaining Unstabilized
Yirae
FIGURE 1 Ideal Growth Curve -- Continuous Operation
II DISPERSED GROWTH ACTIVATED
SLUDGE PROCESS
When true log growth occurs, the number of
organisms should double in size every 20 -
60 minutes. This may occur with food levels
of 1, 000 - 10, 000 mg/1 as in bacterial
culture work. In most waste treatment
plants, however, typical air supply and
nutriment levels do not support log growth
very long and usually for a small percentage
of the organism population.
Dispersed growth, therefore, is a basic
process variant which is primarily of
academic interest. In the presence of a
large excess of soluble organic food matter,
the microorganisms operate at high energy
levels in assimilating this food matter.
Settleable suspended solids are not removed
from the effluent and returned to aeration for
reuse. New cellular matter is formed as
fast as it is lost with the effluent. A low
solids equilibrium can be maintained without
the need for return of sludge.
SE.TT.bp.2.7.71
19-1
-------
Activated Sludge Waste Treatment Process Variations and Modifications
The dispersed growth activated sludge
treatment process utilizes the simple flow
arrangement shown m Figure 2. Note that
final clarification of the effluent is omitted.
Because of the low BOD,, removal and high
loss of cellular matter in the effluent, the
dispersed growth process has limited use.
Primary use is for relief of loading for
subsequent treatment.
IE HIGH RATE OR SHORT TERM ACTIVATED
SLUDGE PROCESS MODIFICATIONS
The high rate process operates at high BOD,,
loadings or food-to-microorganisms ratios
and has a high cell synthesis rate resulting m
maximum production of excess sludge. This
generally amounts to about 0.75 pound of sludge
produced for every pound of BOD^ reduced by
the process. The high rate process also has
the smallest overall oxygen requirement which
is approximately 0. 45 pounds of oxygen per
pound of BODg reduced.
Only a small amount of sludge is recycled to
the aeration tank, and the aeration period is
kept short. The fraction of oxidizable organic
matter removed is in the range of 60 - 70
percent. The process uses a minimum of
aeration volume, oxygen and aeration power
for the load treated. While the system
upsets easily, it returns to usual operating
efficiency quickly. Sludge produced usually
settles and compacts readily.
Aside from lower BOD^ removal, its biggest
limitations are from high waste sludge pro-
duction which requires large digestion
facilities and results in high sludge disposal
costs.
A High Rate or Modified Activated Sludge
High rate or modified activated sludge
treatment utilizes the simple aeration
tank-final clarifier arrangement which is
also standard for conventional treatment.
This is shown in Figure 3 below:
Raw Waste ^
Primary
Sedimentat Ion
Aeration —
Tank ^ v
V V
Effluent
• u ^
Tank
Sludge I to Digester
, Discharge to Receiving
Waters.
FIGURE 2 DISPERSED GROWTH
Raw
Vastc
71
Primary
Sedimentation
Tank
Acration
Sludge j to ^
Y Digester 3
Excess Sludge
Cz
Tank
D
4-
Retum & Excess Sludge
Final
Final
Sedinentation
Tank
Effluer
FIGURE 3 High Rate or Modified Aeration
19-2
-------
Activated Sludge Waste Treatment Process Variations and Modifications
The step loading method of feeding has
also been employed with this flowsheet.
Primary treatment may be included as
shown, or it can be eliminated from the
flowsheet if desired.
B Supra-Activation
Supra-activation is a high-load process
modification giving a degree of treatment
similar to that achieved by modified
aeration and using the same structures."
It may be used for "roughing" treatment
preceding other processes. Patent
applications have been made by W.H. Torpey
for this process with assignment of the
rights to Chicago Pump. The principal
advantage of this variation is that for tank
loadings of 200 to 800 pounds of BOD,. per
1000 cubic feet of aeration tank capacity,
the aeration tank required is approximately
one-quarter of the size of that required
for the Modified Aeration process and
approximately one-eleventh of the size
required for the Conventional Activated
Sludge process.
C Activated Aeration
Figure 4 below shows a modification of the
High Rate process that is referred to as
activated aeration.
Activated aeration is capable of providing
an effluent of intermediate quality at 25%
savings in air compression power costs
when compared with the straight high rate
process. The difficulties of control
experienced with high rate treatment are
avoided since it is not necessary to recycle
active solids through the system. Some
reductions in sludge production are also
realized.
Final
Raw Waste
Effluent
Return & Excess Sludge
Final
Effluent
Raw Waste
Aeration
Tank
Final
Sedimentation
Tank
Aeration
Tank
Sedimentation
Final
Tank
Sludge to Thickener
and/or Digester
FIGURE A Activated Aeration
19-3
-------
Activated Sludge Waste Treatment Process Variations and Modifications
IV CONVENTIONAL ACTIVATED SLUDGE
PROCESS MODIFICATIONS
Conventional operation is the oldest and most
commonly used mode of the activated sludge
treatment. It is versatile and represents a
good compromise among treatment performance,
capital, operating and sludge disposal costs
for plants of the household variety to the
large city plant. Economics and operational
control are favored in the large plant facility.
Effluent quality will satisfy most government
standards. Additional solids, nitrogen, and
phosphorus removal may be required m
critical situations. Some tradeoff is possible
between aeration and sludge disposal cost -
more aeration, less net sludge residual.
Any biological process performs better at
uniform low loading, non-toxic environment
and favorable conditions. Operating control
requirements rapidly rise as these criteria
depart from the ideal due to design, capacity
or loading factors. It is a cause and effect
situation. High performance expectancy for
a natural process compressed m terms of
time and space requires more operational
control.
A Conventional Plug-Flow Activated Sludge
The original standard flowsheet uses what
we now call plug-flow aeration tank design.
These tanks were long rectangular basins
with the waste introduced at one end and
discharged at the opposite end some
distance away.
Figure 5 shows a common version of this
modification using series, multi-pass,
'aeration with return sludge and influent
introduced at the tank inlet.
It was believed that this flow arrangement
was very desirable since it reduced short
circuiting to a minimum, insuring that all
of the waste remains under aeration for
the maximum peribd of time.
On the other hand, this kind of flow pattern
produces a continually changing environ-
ment within the aeration tank. During
passage, the available food is being used
up while the population of microorganisms
at first increases and then decreases.
Under these conditions, there is a situation
of constantly varying food/microorganism
ratio. The BOD,, loading is high at the
head end of the aeration basin and low at
the effluent end with an average loading
occurring only briefly somewhere during
aeration.
Raw
Waste
Primary
Sedimentation
Tank
Sludge ^to Digester
Excess Sludge
Aeration
c-
Tank
Pinal
Settling
Tank
Return & Excess Sludge
Final
^
Effluent
FIGURE 5 Conventional Plug-Flow Activated Sludge
19-4
-------
Activated Sludge Waste Treatment Process Variations and Modifications
Since loading is continually changing, the
environment is forever changing and the
relative predominance of the various species
of microorganisms continuously change.
Equilibrium is never obtained and the
system is always out of balance. Under
these conditions, the microorganisms work
less efficiently than if they are provided
with a constant environment
1 Characteristics
a Detention time in aeration tank --
4 to 8 hours.
b Loading -- 25 to 35 lbs BOD per day
per 1000 cu. ft. of aeration tank
capacity, or 0.2 to 0,5 pounds BOD^
per pound of volatile suspended
solids (VSS) under aeration.
c Return sludge rate -- return sludge
ratios for this type of system usually
maintained between 25 to 50 percent.
As the loading increases, solids
return should increase.
d Air introduced uniformly along tank
length.
e Highest organic loading and hence
highest oxygen demand at head of
aeration tank.
f Waste stabilization proceeds along
length of tank -- hence lowest oxygen
demand at outlet end of tank.
g Excess sludge production - for
systems treating domestic wastewater,
the volume of excess sludge to be
disposed of is usually about 1. 5
percent of the influent flow or about
0.5 lbs/lb BOD,, removed.
h Most process modifications were
adapted to improve conditions to
make better use of biological
stabilization in available space and
time.
B Tapered Aeration Activated Sludge
A relatively high initial oxygen demand is
normally encountered at the influent end
of the aeration tank of a conventional
activated sludge treatment plant. As the
flow passes down the length of a tank, the
oxygen demand of the waste is gradually
satisfied and the remaining oxygen demand
becomes less and less.
The Tapered Aeration process shown in
Figure 6 is designed to supply more oxygen
at the head end of the system where the
load is highest and then reduce it pro-
portionally with the organic loading along
the length of the aeration tank.
AIR IN
PRIMARY
RAW WASTE w
m lGEDIMENTATION
TANK
INLET
SLUDGE TO DIGESTER
EXCESS SLUDGE
—I I i
<> I i I I
OUTLET
FINAL
SEDI -
MENTATION
TANK
RETURN & EXCESS SLUDGE
FINAL
EFFLUENT
FIGURE 6 TAPERED AERATION
19-5
-------
Activated Sludge Waste Treatment Process Variations and Modifications
1 Flow diagram same as Conventional.
2 More air introduced at the inlet end of
the aerator than in subsequent aerator
capacity.
3 Results in more efficient use of air and
improved aeration power economy.
4 Detention times and loadings similar to
conventional system -- Tapered
Aeration has a volumetric loading of
about 35 pounds BOD,, per day per
1000 cubic feet of aeration tank capacity.
C Step-Aeration Activated Sludge
Another way to even out the oxygen demand
in the mixed liquor of the aeration tank is
to introduce the waste flow at intervals
throughout the length of the tank. This
process is termed Step Aeration but might
more correctly be termed Step Loading.
This system is shown in Figure 7.
If the aerator happened to be divided into
four passes, the return sludge usually
would be introduced at the inlet of the first
pass and flowing through the rest of the
passes in series. Sewage may be added
in any desired portion at the head end of
any or all of the passes. Ordinarily,
one-quarter of the primary sewage effluent
flow is admitted to Pass B, one-half to
Pass C and one-quarter to Pass D. The
net result is a better mixed system with
more equalization of the load. The
advantages claimed for this method of
waste loading are: higher BOD& removal
with shorter detention time, good sludge
settling with uniform degree of treatment
and more efficient oxygen transfer. This
modification is particularly good for waste-
waters with high organic loadings
providing solids transfer is good. The
benefits gained are those obtained in the
use of a more completely mixed conventional
system with the following characteristics
1 Sewage introduced at various points
along length of aeration tank.
EXCESS SLUD0E
RETURN & EXCESS SLUDGE
RETURN SLUDGE
RAW
WASTE
PRIMARY
SEDIMENTATION
TANK
AERATION
Q
TANK
ji
FINAL
SETTLING
TANK
FINAL
»
EFFLUENT
SLUDGE TO DIGESTER
FIGURE 7 STEP AERATION ACTIVATED SLUDGE
19-6
-------
Activated Sludge Waste Treatment Process Variations and Modifications
2 Evens out organic load and also oxygen
demand.
3 Detention time in aeration tank --
3 to 4 hours.
4 Loading -- 50 to 75 lbs BOD per day
per 1000 cu. ft. of aeration tank.
5 Return sludge ratio -- 25 to 50%.
D Complete - Mix Activated Sludge
Aeration systems which approach complete
mixing are easily obtained by the proper
choice of aeration tank shape, method of
feeding, and aeration equipment. Figure
8 below shows one possible arrangement.
This is more readily obtained in small
aerators.
Greater dispersal of the influent and more
rapid mixing with the tank contents is
desired. Single or multiple point feed and
discharge can be used depending on the
size and type aeration system provided.
Mechanical aerators, are significantly
different from diffusion devices in two
respects. First, they produce a higher
degree of mixing intensity and, second,
they mix m all directions. The flow
pattern due to mixing is not only perpen-
dicular to the direction of process flow
but also in the same direction and against
it. More complete mixing is likely as
compared to conventional diffused air
placement.
1 Incoming sewage and return sludge
are completely and instantaneously
mixed with the aeration tank contents.
2 Results in uniform environment that
allows much higher loadings and
shorter detention times than with any
other modification.
3 More likely to dilute shock loads.
4 Loading distributed among entire tank
contents, better adapted to high load
ratios.
5 Return sludge ratio - return sludge
ratios should be as high as necessary
considering sludge characteristics
and loading.
E Contact Stabilization
Contact Stabilization uses two separate
aeration tanks to provide two stage sludge
aeration. The principle is to use first
a short (0.5 - 1.0 hour) "contact" stage,
during which a major fraction of the applied
BODj. is transferred from the wastewater
to the sludge solids. This occurs by
adsorption, absorption, mechanical
entrapment, assimilation, filtration, etc.
The sludge is then separated from the
treated liquid in a clarification step.
The sludge moves to a "sludge reaeration"
tank with a detention time of 4 - 8 hours,
which allows the sludge stabilization to
continue. This process is attractive when
used on wastewaters containing high
proportions of particulate materials such
as domestic waste.
Rav
Waste
Pinal
Complete - Mix
Aeration
Tank
Effluent
Return Sludge
Sludge to Digester
Return & Excess Sludge
Excess Sludge
Primary
Sedimentation
Tank
Final
Sedimentation
Tank
FIGURE 8 Complete - Mix Activated Sludge
19-7
-------
Activated Sludge Waste Treatment Process Variations and Modifications
The process may be operated to give
excellent treatment with low net sludge
production. The provision for discharge
of the effluent after short period aeration
with continued aeration of the more
concentrated activated sludge means that
total tankage for aeration may be reduced
as much as 50% below that for conventional
processing. Wastewaters containing
predominantly soluble components may
not be transferred to the solids phase rapidly
enough for good treatment. The contact
process tends to recover more rapidly
from shock loads.
It is often possible to operate an over-
loaded Conventional Activated Sludge
system as a Contact Stabilization system
by changing to step feed and adding the
feed later during aeration. Redesigning
may only involve changes in the plant
piping or relatively minor modification
to the aeration tank layout. The settling
unit capacity, of course, would have to
be increased as flows approach or exceed
the original design values.
1 Process modification depends on
ability of activated sludge to trap
colloidal and suspended organic matter.
2 Works best with wastes high in colloidal
organic matter.
3 Reaeration carried out only on settled
sludge volume.
4 Detention time in initial aeration tank--
0. 5 to 1 hour.
5 Detention period in reaeration tank --
4 to 8 hours.
6 Loading -- 35 to 70 lbs, BOD,, per day
per 1000 cu. ft. of combined aeration
tank volume.
RAW WASTE
PRIMARY
SEDIMENTATION
TANK
SLUDGE
rl
IGESTER
EXCESS SLUDGE
CONTACT
AERATION
TANK
FINAL
> SETTLING
TANK
SLUDGE
REAERATION
TANK
FINAL
EFFLUENT
FIGURE 9 CONTACT STABILIZATION
19-8
-------
Activated Sludge Waste Treatment Process Variations and Modifications
V EXTENDED AERATION ACTIVATED
SLUDGE PROCESS MODIFICATIONS
The extended aeration process represented
by the two modifications shown in Figures
10 and 11 is designed for low loading as com-
pared with previously discussed activated
sludge operating modes. It has also been
referred to as the total or complete oxidation
process. Solids digestion does limit net
sludge production but does not eliminate it.
Extended aeration typically operates at very
low food-to-microorganism ratios and
produces a minimum of residual products.
About 0. 15 pound of excess sludge is produced
for each pound of BOD^ reduced.
Minimum sludge production is not obtained
without penalty. There is maximum oxidation
of organic matter to the ultimate end products
of carbon-dioxide and water with high power
requirements for supplying that oxygen. As
loading decreases, more oxygen is used for
sludge stabilization.
The unit rate of oxygen utilization, oxygen
uptake rate, usually decreases so that a long
aeration time is required.
In theory, the rate of sludge build-up is
balanced in the extended aeration process
by the rate of sludge destruction. The process
can be operated in a balanced state, but the
ultimate plant effluent discharge quality will
be lowered with the loss of incompletely
digested solids via the effluent.
Where a plant is fully loaded and a highly
polished effluent is required, it will be
necessary that excess sludge be wasted at
intervals of one to two weeks. The surplus
sludge may be discharged without offensive
odors, for direct drying on open drying beds,
worked into soils or may be diverted to a
sludge storage tank and accumulated for
ultimate disposal on restricted areas. Cold
weather operation usually shows poor sludge
stabilization and settling. Generous holding
tankage is required.
FINAL
SETTLING
TANK
FINAL
RAW WASTE
EFFLUtNT
RETURN SLUDGE
--- FOR SLUDGE STABILIZATION OR
HOLDING BEFORE WASTING
AERATION
TANK
SLUDGE
STORAGE
TANK
FIGURE 10 EXTENDED AERATION PACKAGE TREATMENT PLANT
19-9
-------
Activated Sludge Waste Treatment Process Variations and Modifications,
MmnoNniTCH
Brush -
AeTator
Raw Waste
Return Sludge
Final
Sedimentation
Tank
Final ^
Effluent
FIGURE 11 Extended Aeration Oxidation Ditch
V
1 Usually smaller package type plants.
Economics limit these to relatively
small sizes (up to 0. 5 mgd capacity).
Used for small communities, trailer
courts, motels, etc.
2 Long aeration period (24 hours) results
in aerobic digestion of solids.
3 Designed for no sludge wasting, but will
always have slow buildup of inert solids
that will be lost in effluent. Some
sludge control and wastage is necessary
to obtain high quality effluents.
4 While screening is desirable, primary
sedimentation may be omitted.
5 Sludge disposal costs are relatively low,
but large aeration volume and aeration
power requirements are encountered.
6 Extended aeration may require more
than double the unit oxygen requirement
of the conventional process. As much
as 1. 8 pound oxygen per pound BOD^
reduced may be used by extended
aeration while process with separate
solids removal may use about 0.4-0.8
pound oxygen per pound BOD^ reduced.
7 High effluent nitrification causes
frequent problems with the final
clarification especially when scum
control is omitted on the final clarifier.
VI SUMMARY
Many of the activated sludge waste treatment
process modifications discussed in this
outline are not really separate processes m
themselves, but are actually operational
modes of the same thing. The major differ-
ences between them involve variations in
waste loadings, food-to-microorganisms
ratios and in-plant flow patterns. Most
waste treatment plants are hybrids of two
or more of the process modifications dis-
cussed. Good design practices provide the
operator with the capability to change plant
operational characteristics as may be
advantageous depending on influent nature
concentration and flow pattern.
Table 1, which follows, lists the typical
operational characteristics and design
criteria for the major activated sludge
waste treatment modifications considered
in this outline.
19-10
-------
TABLE 1. OPERATIONAL CHARACTERISTICS OF ACTIVATED SLUDGE WASTE TREATMENT MODIFICATIONS
Name of
Process
Modification
MGD-Plant
Design Flow
Plant Design
lb BOD j / Day
Aerator
Loading
(lbs BOD5
per day
per 1000
cu ft )
Aeration
Period in
Hours
(based on
design flow)
Min Air
Require-
ments
cu ft
MLSS/lb BOD5
Ratio
Return Sludge
Rate - (percent
of design flow)
Detention
Period Final
Settling Tanks
(hours)
Surface
Settling
Rate
(CPD /
sq ft.)
s°d5
Removal
(percentage)
lb BOD5
,\\ Conventional
%"
To 0 5
0.5 - 1.5
1 5 up
To 1000
1000 - 3000
3000 up
30
30 - 40
40
7 5
7 5 - 6.0
6.0
1500
2/1 to 4/1
15 - 75
Ave 30
3 0
2.5
2 0
600
700
800
95 +
.J 1 Modified or
-XI "High Rate"
To 0.5
0 5 - 1.5
1. 5 up
2000 up
100
2 5 up
400 - 1500
1/1(or less)
10 - 50
Ave 20
3.0
2.5
2 0
600
700
800
60 - 75
Vf Step -
Aeration
0.5 - 15
1 5 up
1000 - 3000
3000 up
30 - 50
50
7 5-50
5.0
1500
2/1 to 5/1
20 - 75
Ave 50
2 5
2 0
700
800
90 - 95
Contact
Stabilization
To 0 5
0 5-15
1 5 up
To 1000
1000 - 3000
3000 up
30
30 - 50
50
3 0*
3 0 - 2.0
1.5 - 2 0
1500
2/1 to 5/1
50 - 150
Ave 100
3.6
3.0
2.5
500
600
700
85 - 90
fad Extended
—Aeration
To 0 05
0 05-0 15
0 15 up
All
12.5
24
2000
10/1 to 20/1
50 - 200
Ave 100
4 0
3 6
3 0
300
300
600
75 - 85
""Aeration Period in Contact Zone which represents 30 - 35 percent of the total aeration capacity.
-------
Activated Sludge Waste Treatment Process Variations and Modifications
Table 2 groups the activated sludge process
modifications according to waste loadings.
REFERENCES
1 Eckenfelder, W.W., Jr. Biological
Conversion Process, Unpublished paper
prepared for FWQA manual on sewage
treatment processes. 1969.
Lesperance, T.W. A Generalized
Approach to Activated Sludge, Parts
1-7, Waterworks and Wastes Engineering,
Ruben Donnelly Publishers, New York.
April-October 1965.
TABLE 1
WASTE LOADING CHARACTERISTICS
OF ACTIVATED SLUDGE TREATMENT
PROCESSES
1. High Rate AS Process Variations
(Waste Loading > 1.0 lbs COD lib MLVSS/day
Dispersed Growth
High Rate
Modified Aeration
Supra Activation
Activated Aeration
2. Conventional AS Process Variations
(Waste Loading 0. 2 to 1.0 lbs COD/lb
MLVSS/day)
Complete Mix
Plug Flow
Tapered Aeration
Step Aeration
Contact Stabilization
Stewart, M. J, Activated Sludge Process
Variations -- The Complete Spectrum,
Water and Sewage Works, Pages R-241
through R-262, Reference Number. 1964.
3. (Waste Loading < 0. 2 lb COD/lb MLVSS day)
This outline was prepared by James A.
Extended Aeration Montgomery, Sanitary Engineer, River
Oxidation Ditch Basin Planning, OWP, Washington, DC 20242.
ELL
19-12
-------
CASE HISTORIES EFFLUENT EXCELLENCE FROM PRESENTLY
AVAILABLE SECONDARY TREATMENT PROCESSES
I INTRODUCTION
A Pollution can be greatly reduced, almost
overnight, by maximum use of existing
secondary treatment processes,
B Activated sludge plants can produce final
effluents containing considerably less than
10 mg/1 suspended solids and 5-day BOD.
Overall reductions of 95 to 99 percent are
possible.
To obtain such results, the plants must be
properly designed with adequate built in
capacity and flexibility; plant characteristics
must be appropriate to the incoming load;
and the process must be skillfully controlled
by conscientious qualified operators.
II SIOUX FALLS, SOUTH DAKOTA
A Plant Description
Treats 3. 5 mgd strong meat-packing waste
and 6.0 mgd domestic sewage. High rate
trickling filters pre-treat packing plant
wastes, activated sludge treats domestic
sewage and polishes industrial wastes.
B Feature Story - 99% Reductions
Has demonstrated ability to provide 99%
reductions during summertime (August)
when plant was operating within design
loading (Figures 1 and 2). BOD reduced
from 900 to 9, TSS from 650 to 5 (Figures 3
and 4).
C Improved Operational Control
Wintertime pollutional load to river cut in
half by improved operational control alone.
1 Control tests
Started using:
Settlometers for sludge density
Centrifuge for sludge density
Blanket finder for clarifier sludge
blanket
Turbidimeter for current effluent
quality
2 Interpretation
Sludge condition, system equilibrium,
and process demands are the key items
for systeftn control.
3 Control adjustments
a Increased return sludge percentage
from 30% to more than 100%.
b "Tight-rope" sludge wasting control
to increase sludge concentration and
activity without upsetting aerators
and clarifier s,
4 Improved effluent quality
Former 30 mg/1 BOD reduced to 20 mg/1
Former 35 mg/1 TSS reduced to 13 mg/1
D Significant Loading Characteristics
See Table No. 1.
E Favorable Features at the Existing Plant
1 Dedicated supervision and operation
2 Efficient aerators (Not spiral flow)
3 Effective suction type final clarifier
sludge removal mechanism
PC. WAS.9.1.69
20-1
-------
Effluent Excellence from Secondary Treatment Processes
100
1001
98.0
99.3
FIG. 1
SIOUX FALLS, S.D.
5 DAY BOD REDUCTIONS
THROUGH ENTIRE PLANT
(AUG & DEC., 1967)
OjOI 1 10 50 90
% OF TIME EQUAL TO OR LESS THAN
99 99
—
»9i—
983 —
^ — 97 S
^^"¦—95*
FIG.2
i
SIOUX FALLS, S.D.
*/
o /
SUSPENDED SOLIDS REDUCTIONS
THROUGH ENTIRE PLANT
(AUG
. & DEC., 1967)
95
(/>
u
D
O
90
65
0 01
50
90
% OF TIME EQUAL TO OR LESS THAN
99 99
-------
Effluent Excellence from Secondary Treatment Processes
FIG.3
SIOUX FALLS,S D
FINAL EFFLUENT BODg
MONTHS OF AUG A DEC., 1967
80
73
70
U SO
Q* 40
37
CO 30
26
20
10 20 40 60
% OF TIME EQUAL TO OR LESS THAN
90
96
99 99
90
FIGURE 4
SIOUX FALLS,S.D.
FINAL EFFLUENT TOT. SUSP. SOLIDS
MONTHS OF AUG. & DEC., 1967
80
74
70
60
50
40
33
-1 30
u.
u.
OjOI
10 20 40
% OF TIME EQUAL TO OR LESS THAN
OJ
60
80
90
98
99 99
3
-------
Effluent Excellence from Secondary Treatment Processes
TABLE NO. 1
SIGNIFICANT LOADING CHARACTERISTICS
(Sioux Falls, South Dakota - Activated Sludge Plant)
BOD Load to Aerators
SUMMER WINTER
Pounds per day 18, 000 37, 400
Pounds per 1,000 cu. ft. Aerator 103 160
Pounds per pound mixed liquor solids 1.3 1.2
Clarifier Surface Loading Rate
Gals./sq. ft./day 720 640
BOD Reductions
Total - Trickling filter & activated sludge 99 97
Activated sludge alone 95 90
TSS Reductions
Total - Trickling filter &. activated sludge 99 96
Activated sludge alone 96 83
Air (Approximate Range)
12 to 36 million cu.ft. / day
0.5 to 3.0 cu. ft. /gal.
300-1, 000 cu.ft. /lb. BOD
Return Sludge - 30% to 200%
Aeration Detention Time - 1. 5 to 3. 0 hr.
4 Complete mixed aerator flow pattern
5 Adequate return sludge pumping capacity
F Plant Deficiencies
1 Activated sludge plant overloaded
2 Trickling filters freeze up in winter
3 Disproportionately small aerator/
clarifier volume
4 Not enough air
20-4
5 No scum removers on final clarifiers
6 Impossible to make precise control
adjustments. (Not enough meters, no
remotely controlled mechanical valve
actuaters, and no automatic sensor-
controllers. )
III METROPOLITAN ST. LOUIS SEWER
DISTRICT - MSD
Coldwater Creek Wastewater Treatment
Plant (Activated Sludge)
A Basically, this is a conventional 21 mgd
standard rate activated sludge plant.
-------
Effluent Excellence from Secondary Treatment Processes
There are 6 aerators with spiral flow
pattern diffusers and 4 final clarifiers
with plow-type sludge scrapers.
B Feature Story - Pollution reduced to 1/4
its former strength by operation control
alone.
Before After
1 Suspended Solids
Raw (mg/1) 173 198
Primary Effluent (jpng/1) 155 142
Final Effluent (mg/1) 92 16
Activated Sludge Reduction 40% 89%
Total Plant Reduction 46% 92%
E Favorable Features at the Existing Plant
1 Dedicated supervision and operation
2 Adequate plant capacity for present dry
weather flow
3 Multiple unit aerator and clarifier groups
F Plant Deficiencies
1 Plow-type sludge scrapers in final
clarifiers
2 Spiral flow diffuser placement in
aerators
2 5-Day BOD
Raw (mg/1) 150
Primary Effluent (mg/1) 152
Final Effluent (mg/1) 40
Activated Sludge Reduction 74%
Total Plant Reduction 73%
162
130
_9
93%
94%
D Improved Operational Control
1 Changed aerator/clarifier ratio - by
taking one of the 4 clarifiers out of
service and placing an additional aerator
in service. Theoretical full load
characteristics as follows-
Changed
Former
To
Aerator/Clarifier Combination
3A/4C
4A/3C
Mixed Liquor (% by Centrifuge)
7. 2
3. 4 IV
Return Sludge (% of Sewage Flow)
93
30
Flow Capacity (MGD)
13. 2
14. 5 A
Aerator Detention (HRS)
3. 0
5. 4
Clarifier Detention (HRS)
2.0
2. 0
2 Control Tests & Interpretation
Introduced use of settlometers, centrifuge,
blanket finder and turbidimeter to detect
process balance and demands.
3 Control Adjustments
In this case Reduced return sludge
pumping. Increased air
supply and excess sludge-
wasting rates.
3 Hydraulic short circuiting plus strong
velocity currents in final clarifiers
4 No scum removal for final clarifiers
5 Inadequate return sludge capacity
6 Meter problems, and lack of remotely
controlled mechanical valve actuators
or automatic sensor-controllers limit
process controlability.
G Present Status
1 Presently obtaining 90% reductions
2 Could cut pollutional load in half again
if obvious plant deficiencies were
corrected
CONCLUSIONS
The activated sludge process can produce
sparkling clear final effluents.
Plants can and should be properly designed
(or modified) and operated to obtain their
maximum inherent purification efficiencies
needed to abate pollution of our national
water resources. These include
B Design
1 Provide adequate capacity for growth
and equipment outages.
2 Flexibility - (Give the operators a
chance.)
20-5
-------
Effluent Excellence from Secondary Treatment Processes
Provide ability to increase or decrease
number of aerators or clarifiers, convert
to a complete mixed system or to step
aeration as required.
3 Avoid "spiral flow" aeration.
4 Use suction devices in final clarifiers
for rapid removal of fresh sludge.
Also provide surface scum removers.
5 Make air supply, sludge return and
sludge wasting equipment truly variable
and conveniently controllable.
6 Provide essential meters and sensors,
remote valve actuators and automatic
ratio controllers where required.
C Operation
1 Recruit and retain conscientious,
intelligent, trained, and certified
plant operators.
2 Provide practical "on-the-job" work
experience type training.
3 Provide 24-hour around-the-clock
operation. Test, evaluate and adjust
process at least once per 8-hour shift.
4 Make the best use of existing facilities,
guide counsel, and consulting engineers
in designing needed improvements and
additions.
This outline was prepared by A. W. West,
Chief, Pollution Evaluation Section, TA & I
Branch, 5555 Ridge Avenue, Cincinnati, OH.
20-6
-------
TRICKLING FILTERS
I INTRODUCTION
A Trickling filters have been used for many
years for the treatment of municipal liquid
biological wastes. Although it is one of the
oldest treatment devices, the relationship
among the factors affecting the amount of
waste removal achieved in a trickling filter
has remained obscure.
B Trickling filters are not filters at all, but
basically only a pile of rocks providing
surface area upon which slime organisms
cling and grow. These microbes feed on
the dissolved food matter contained in the
sewage or industrial waste effluent applied
to the filter. When too thick a slime layer
accumulates, anaerobic conditions develop
at the media surface A natural mechanism
results for cleaning the filter with the
periodic "sloughing" of the slime layer
from the surface of the filter media.
These solids that are sloughed off are
collected through final clarification of the
filter effluent.
II TRICKLING FILTER COMPONENTS AND
THEIR FUNCTIONS
A Distribution - rotary or fixed nozzle
Provides intermittent application, wets
all media surfaces, applies sewage
effluent uniformly.
B Media
Supports slime, provides slime-sewage-
air interfaces, permits ventilation or
air flow.
C Under drainage System
Collects and conveys effluent, admits or
draws off air, supports filter media.
D Secondary Clarifier
Settles agglomerated solids and "sloughed"
slime growths from final effluent, final
clarifier overflow rate varying between
800-1000 gallons per day per square foot
(gpd/sq ft).
Ill ADVANTAGES AND LIMITATIONS OF
THE TRICKLING FILTRATION PROCESS
A Advantages
1 Relatively high nitrifying effect upon
effluent
2 Low operating cost
3 Ability to function under extreme
weather conditions
4 High efficiency in BOD removal
5 High efficiency in suspended solids
removal
6 Rugged resistance to shock loads
7 More complex biota than for activated
sludge
B Limitations
1 High head losses
2 Odor and fly nuisances
3 Large land area required
4 High initial construction cost
5 Head losses may require pumping
6 Forced ventilation may be necessary
SE.AE.tf. 5. 8. 70
21-1
-------
Trickling Filters
7 Trickling filter effluent clarification
may be less complete due to association
with anaerobic slime layers.
IV CLASSIFICATION OF TRICKLING FILTERS
A Low Rate or Standard Trickling Filters
1 Hydraulic loading
1-4 million gallon per acre per day
(mgad) 25-100 gpd/sq ft
2 Organic loading
220-600 lbs. BOD5/acre-ft/day
5-15 lbs. BOD5/1000 cu ft
3 Recirculation
usually not
4 Filter depth
6-10 ft (ave. 7')
Most of the very early filters were of
this type.
B High Rate Trickling Filters
1 Hydraulic loading
4-44 mgad
200-1000 gpd/sq ft
2 Organic loading
660-13, 000 lbs. BOD5/acre - ft/day
15-300 lbs. BOD5/1000 cu ft
3 Recirculation
normally provided
4 Filter depth
3-7 ft (ave. 5')
Most of the filters constructed in recent
years have been high-rate filters. These
filters were built with various depths, and
organic loadings.
The performance of biological treatment
units of this type is dependent upon the
volume of ACTIVE growth present in and
on the filter media. The size of the filter
and the filter media determine the amount
of space available for the growth of the
biological slime mass.
The rate of application of the waste
influences the amount of growth that will
develop. The two types of loading
(i.e. organic loading and the volumetric
or hydraulic loading) have opposite effects.
The greater the amount of available
organic matter, the greater the food
supply and expected growth. Recirculation
increases trickling filter efficiency,
however, high dosage rates increase
scour, dislodge slime growth, and reduce
the volume of active growth present m
and on the filter media. It is noted that
organic loading has greater influence on
trickling filter efficiency than hydraulic
loading,
C Super Rate or Roughing Filters
1 Hydraulic loadmg
up to 1000 mgad
2 Organic loading
(see comment noted below)
3 Recirculation
normally provided
4 Filter depth
up to 40 feet using manufactured
plastic filter media instead of rock
or stone
This process is usually associated
primarily with treatment of industrial
wastes.
In some recent filter designs, loads
greater than those for the high-rate filters
have been used. This is particularly true
for manufactured filter media. Presumably
the ratio of the useful surface area of the
21-2
-------
Trickling Filters
media to the volume of the media is
greater for cases in which higher
efficiency of BOD removal per unit volume
of filter is obtained.
It appears that some allowance, by use of
some factor, for the effect of increased
surface area within the same volume of
manufactured filter media should be made.
V DESIGN CONSIDERATIONS FOR TRICKLING
FILTRATION SYSTEMS
A Common Flow Diagrams
1 A general flow diagram which represents
most of the possibilities of recirculation
of effluents and underflows is shown in
Figure 1 could be cut off between the
intermediate clarifier and the second
stage filter, discarding the second
stage filter and final clarifier.
2 Figure 2 shows a few of the more
common flow diagrams.
B Factors in Trickling Filter Design
It appears that the efficiency of a trickling
filter is dependent upon all or some of the
following variables:
1 Composition and characteristics of the
waste influent
2 Organic loading to be applied to the
filter
3 Pretreatment by sedimentation or other
processes
4 Hydraulic loading to be applied to the
filter-recirculation ratio and system
5 Filter bed characteristics, volume,
area, and depth
6 Type of filter media selected, such as
surface to volume of support media and
void space
7 If aeration or forced ventilation is to
be provided
8 Wastewater and air temperature
C Effects of Recirculation
1 Part of the organic matter in the raw
waste feed is brought into contact with
the slime organisms more than once.
2 Recirculated effluent contains active
microorganisms not found in such
quantity in raw waste, thus providing
seed continuously.
3 Diurnal organic waste loadings are
distributed more evenly.
4 The continuation of waste application
to the filter during periods of low
flows (night time) precludes long
detention periods which may result
in septicity. Stale sewage is freshened.
Slimes do not dry out.
5 Increased hydraulic loading through
recirculation improves uniformity
of waste distribution, increases
sloughing, and reduces clogging
tendencies.
6 Higher velocities and continual scouring
also produces conditions less favorable
for the growth of filter flies.
7 Continual seeding with active slime
organisms and enzymes stimulates
hydrolysis and oxidation and increase
the rate of biochemical stabilization
of the waste.
8 Recirculation will increase operating
costs because of the necessary pumping
of the return effluent.
9 Wastewater temperatures may be
reduced as a result of the number of
passes of the liquid through the filter
During cold weather, this may result
in decreased biochemical activity and
reduced efficiency of treatment
provided.
This outline was prepared by J. A. Montgomery,
Sanitary Engineer, FWQA Manpower and
Training Activities, PNWL, Corvallis, OR
21-3
-------
Trickling Filters
TRICKLING FILTER FLOW AND RECYCLE
RECYCLE
INFLUENT
EFFLUENT
UNDERFLOW RECYCLE
UNDERFLOW RECYCLE
FIGURE 1
TRICKLING FILTER FLOW AND RECYCLE
FIRST STAGE RECYCLE
T"*
SECOND STAGE RECYCLE
OMtn
FIRST STAGE RECYCLE
SECOND STAGE RECYCLE
tfttrtr
nan*r
am
FIRST STAGE RECYCLE
SECOND STAGE RECYCLE
MT*&-
p/crot.
trmt.
EFFLUENT
FIGURE 2
21-4
-------
EXPERIENCE IN THE USE OF RAW SEWAGE LAGOONS
I INTRODUCTION
A Lagoons receiving raw sewage have
become very popular, particularly among
smaller municipalities where low con-
struction and operating costs usually offer
a significant financial advantage over
other conventional treatment methods.
Lagoon installations in the Missouri
Basin serving as the sole mode of treatment
now number several thousand.
U HISTORY OF DEVELOPMENT
A As early as 1920, a few cities in
California, Texas, North Dakota, and
probably other states were using lagoons
as a means of treating municipal sewage.
However, in each case it seemed to be
more the result of accident than actual
design.
1 About this time, a student of the
University of Texas made a study for the
State Department of Health to ascertain
why sewage from the town of Palestine,
which was discharged into a small
swampy area, was converted to a fresh
sparkling stream after a few miles.
The report that aquatic plants played
an important part in the oxidation of
this sewage was subjected to ridicule.
However, a short time later, the State
Sanitary Engineer recommended that
Abilene, Texas construct a small dam
and pond their sewage until a sewage
treatment plant could be built. This
early lagoon functioned successfully,
and during the 1930's Texas A & M
College became interested in the
operations at Abilene and constructed
a 14-acre unit to carry on limited
investigations of lagoon operation.
What happened to this study is not known.
2 In 1924 Santa Rosa, California in an
attempt to provide low-cost sewage
disposal, uncovered gravel beds which
the City Council thought could be used
as natural filters before the city
sewage was discharged into Santa Rosa
Creek. The exposed gravel soon
became sealed from sewage solids,
resulting in a sewage pond about
3 feet deep. The effluent from the
pond resembled the effluent from a
trickling filter. It had no odor and
was easily disinfected. Also, in 1924,
Vacaville, California constructed a
small reservoir in a dry gully to
impound sewage during the winter
months only. Here again, it was
found that this impounded sewage
underwent characteristic reduction in
BOD and increased in dissolved oxygen.
3 In 1928, Fessenden, North Dakota,
completed a sewer system but did not
have funds to complete a treatment
plant. As an emergency measure, the
sewage was drained into a pothole
about a mile from town. Forty years
later, this natural lagoon is still in
operation.
4 The success of these early enterprises
eventually gave engineers and health
authorities some degree of confidence
that a raw sewage lagoon could be
designed and operated satisfactorily in
close proximity to a City.
B Modern Raw Sewage Lagoons
1 The first lagoon built on sound
engineering principles under modern
concepts of treating raw sewage, was
the one placed in operation in 1948 at
Maddock, North Dakota. To my
knowledge, this was the first lagoon
built to receive raw sewage under
plans formally approved by an official
Health Agency. "Engineered lagoons"
had been built m both Texas and
California before this time, but to
receive effluent from primary treat-
ment plants rather than raw sewage.
For the most part, the early facilities
in Texas and California were apparently
SE.BI.sta. 19.7.68
22-1
-------
Experience in the Use of Raw Sewage Lagoons
constructed to store partially treated
sewage effluents for subsequent release
for irrigation.
2 Maddock is a town of approximately
1, 000 people. The initial design
provided 10 acres of water service in
a single cell, a level bottom, a water
depth of 5 feet, and uniform bank slopes.
Observations of this facility and
laboratory analysis confirmed that a
high degree of BOD reduction prevailed
at any point 50 feet or more from the
inlet at the center of the pond.
3 The success of this installation created
considerable enthusiasm by engineers
of the North Dakota State Health
Department, and they soon became
active promoters of lagoons as an
accepted method of sewage treatment.
Several towns in North Dakota constructed
lagoons in 1949. It should be mentioned
that these facilities, and the engineers
recommending them, were harshly
criticized for what was then considered
a backward step in sewage treatment.
With very few exceptions, consulting
engmeers in particular were reluctant
to accept lagoons as sewage treatment
plants.
4 A few City Councils recognized lagoons
as the most economic solution to their
money and water pollution problems,
and insisted that lagoons rather than
conventional plants be designed and
constructed. In some instances,
communities previously unable to
fmance both a sewer system and con-
ventional sewage treatment works,
were able and did construct sewer
systems and lagoons.
5 Endorsement by the U. S. Public Health
Service of lagoons as an acceptable
method of sewage treatment was first
given by the Missouri Drainage Basin
Office, serving a 10-state area in
Midwestern United States. As engineer
in charge of the Water Pollution Control
Program of the Public Health Service
in the Missouri Basin, my own
observations, supported by the
investigative work by Dr. Joe K. Neel,
biologist on my staff, permitted us to
officially endorse this method of
sewage treatment.
6 Enthusiasm also spread to the Taft
Sanitary Engineering Center of the
Public Health Service in Cincinnati,
Ohio, as W.W. Towne, then in charge
of Field Investigations at the Center,
became actively interested in
investigations of facilities then existing
in North and South Dakota. In 1954
the Public Health Service started
limited field investigations of 3 lagoons
in each of the 3 states. The report
brought about a degree of respectability
that raw sewage lagoons had not
previously enjoyed. Today, lagoons
are being used in virtually every State
in the Union, but nowhere do they
predominate in sewage works con-
struction as they do in the Missouri
Basin.
C Missouri Basin Standards
1 One by one and with varying degrees
of enthusiasm, the State Sanitary
Engineers of the 10 Missouri Basin
States began to accept raw sewage
lagoons. Each state promulgated its
own design standards and criteria,
although each was generally patterned
after the original installations in
North Dakota. The great upsurge of
interest in the use of lagoons at many
localities throughout the Basin soon
emphasized the desirability of
documenting the design, construction
and operation practices generally used.
At its 1958 meeting at Deadwood,
South Dakota, the Missouri Basin
Engineering Health Council, consisting
of the Chief Sanitary Engineer of each
of the 10 Basin States, recognized this
need and appointed a committee to
accomplish the ob]ective. It was my
good fortune to be one of the three men
appointed to the Committee, and my
further good fortune that I was requested
to develop a preliminary draft of a
report for review by the other two
members of the Committee.
22-2
-------
Experience in the Use of Raw Sewage Lagoons
2 Upon acceptance by the three-man
committee, the draft was submitted to
each of the 10-state Sanitary Engineers
for review and comment. A succession
of drafts and redrafts followed, and
eventually one was acceptable to each
of the 10 states. This draft was
approved by the Missouri Basin
Engineering Health Council at its
meeting in Jefferson City, Missouri
on January 21, 1960. The Committee
report was carried in the September
1960 issue of the Journal Water Pollution
Control Federation. Today it still
constitutes the most reliable treatise on
design, construction and operation
practices of raw sewage.
D Treatment Process
Primary and secondary treatment processes
are usually accomplished in separate units.
A lagoon accomplishes both gravity
separation and biological reduction in a
single unit.
1 Sludge settles to the bottom. Except
in the vicinity of the inlet, it is rather
uniformly distributed over the entire
lagoon bottom. Circulation resulting
from surface winds and convection
currents contribute to the scatter.
2 Sludge decomposition progresses
somewhat comparable to an unheated
digester. The liquid immediately
above the sludge layer is anaerobic, but
the upper portion of the water reservoir
is normally aerobic. As hydrogen
sulphide is released, it passes upward
through the aerobic zone and reacts with
water before reaching the open
atmosphere. Objectionable odors may
develop only when the entire water
strata is anaerobic. Freedom from
odor is assured only when oxygen is
present in the upper layers. Oxygen
production must thus exceed the demands
of organic decomposition.
3 Light intensity seems to be the most
important influence upon the rate of
photosynthesis. The rate declines with
the autumn and winter declines in light
intensity, with a corresponding
resurgence in the spring and following
periods of overcast.
a Observations by the Public Health
Service at Fayette, Missouri have
shown that there should be at least
1 1/2 langleys of solar radiation
(1 langley = 1 gram calorie per CM )
per day for each pound of BOD
applied per acre of lagoon surface/
day. To insure a safety factor 1 lb
of BOD per acre for 2 langleys is
suggested. Loading in lbs BOD per
acre per day should thus be equal to
one half the minimum daily langley
level for the month with least solar
radiation. This relation does not
hold if ice cover endures over the
winter months.
4 The lagoon provides an environment
favorable for the interactions of algae
and bacteria. Bacteria feed upon
constituents of sewage in solid form
and in solution and render them
innocuous. Algae utilize carbon dioxide
and other substances resulting from
bacterial action and, through photo-
synthesis, produce oxygen needed for
anaerobic bacterial action. During the
detention period, the objectionable
characteristics of sewage largely
disappear.
5 Lagoons normally employ a detention
period of 60 to 90 days, although
detention over 120 days is not uncommon.
A detention as short as 30 days insures
a high degree of coliform removal.
a Series installations increase BOD
removals. Effluent from secondary
units of a series operation has
lower concentrations of algae, color,
turbidity.
b Design of installations in series must
recognize that the entire sludge
load will adhere to the primary cell
22-3
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Experience in the Use of Raw Sewage Lagoons
E Advantages of Lagoons
1 Construction cost is usually much lower
than for other treatment processes.
For smaller communities, where
suitable land is often readily available
at reasonable cost, the cost of sewage
treatment may be reduced by more
than 50 per cent.
a Many smaller communities previously
unable to finance a sewage system and
treatment works have been able to
finance their sewer system and a
lagoon for treatment.
b In certain states, lagoons have saved
communities more than they have
gained through Federal Aid.
2 The cost of maintenance is much lower.
Highly skilled operators are not required.
Maintenance is usually limited to weed
control and dike maintenance. Break-
downs are virtually non-existent.
3 A lagoon has tremendous ability to
handle shock loads. The "slug" is
immediately diluted, and tremendous
"slug loads" are required to upset the
lagoon process.
a Lagoons are well suited for summer
camps, rural schools, motels,
resorts, slaughter houses, livestock
operations, etc. Missouri is
estimated to have more than 1, 000
non-municipal lagoons.
b Design may provide for complete
retention, or may provide for con-
trolled release at a non-critical time.
4 Lagoons may serve well as interim
facilities m developing areas. When
development is adequate to support
trunk or interceptor sewers, the
lagoon can be abandoned at little loss
of investment. Increase in land values
may even offset all construction costs.
This has been widely practiced in
Kansas City, where approximately
40 developer financed lagoons have
served as interim facilities.
a Under its revenue bond program,
Kansas City has constructed 2
lagoon systems to serve the
intermediate portions of large
watersheds, pending the develop-
ment of sufficient customer load to
warrant construction of 8 to 12
miles of large diameter sewers.
5 Lagoons may be used for treating
industrial wastes that are amenable
to biological treatment, or a mixture
of organic industrial wastes and
domestic sewage. Installations are now
successfully serving oil refineries,
slaughter houses, dairy and creamery
establishments, poultry processing
plants, and rendering plants. Special
study should be given industrial wastes
whenever they constitute a significant
portion of the total load. Possible
toxic effects of industrial wastes
should not be overlooked. Toxic
materials in concentration that would
interfere with other biological sewage
treatment processes should be handled
in lagoons only after thorough study
and evaluation.
6 Lagoons may receive raw sewage, or
the effluent of a conventional treatment
plant.
a Numerous instances can be cited
where lagoons provide "polish
treatment, " following a trickling
filter or activated sludge plant.
They are particularly effective in
coliform reduction.
b Where provided initially to receive
raw sewage from sparsley developed
areas, lagoon designed to receive
raw sewage may later be used to
provide secondary treatment, as
primary treatment facilities are
provided to relieve the overload
from increased development.
1) This has been used very
successfully at Kansas City in
the intermediate reaches of the
Little Blue River Basin, and
comparable use is planned in our
Shoal Creek Watershed.
22-4
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Experience in the Use of Raw Sewage Lagoons
7 Lagoons surpass other conventional
treatment processes in reduction of
total phosphorus and total nitrogen.
a Investigations at Fayette, Missouri
demonstrate consistent reductions
of total phosphorus by 85 per cent;
and total nitrogen by 92 per cent.
F Disadvantages of Lagoons
1 Too little is known regarding the many
factors which affect optimum performance
of lagoons. Unfortunately, lagoons
have remained beneath the dignity of
established research talent. Asa
result, research in this field has been
fragmentary.
2 Too frequently, lagoons are permitted
to operate with no supervision or
control. Overloading is not prevented,
and the problem is not apparent until
some critical circumstance occurs --
as a long period of cloudy weather or
an abrupt change from cold to warm
weather. Little can be done to prevent
reoccurrence of the problem.
3 With a breakdown in the process,
lagoons become quite odorous. With
the large area of water surface, a
severe nuisance can occur over a wide
area.
4 A lagoon requires a much greater land
area than do other treatment processes.
Add to this basic area the distance that
should be provided to reasonably isolate
a sewage plant, and a very large area
results. This may be feasible for an
interim period but not as a permanent
installation.
G Summary
1 Sewage lagoons are a proven and
demonstrated method of satisfactory
waste disposal to be considered along
with other accepted methods of treat-
ment, in the engineering and economic
analysis that leads to the final selection
of a sewage treatment process. This
does not imply that the lagoon is the
answer to all sewage problems.
However, a lagoon provides the most
feasible method of sewage treatment
in many instances.
2 Reference material
a The most imformative document on
the design, construction and opera-
tion of lagoons is the Committee
Report of the Missouri Basin
Engineering Health Council. I have
with me several copies of this
publication for any one interested.
b Proceedings of Symposium on
Waste Stabilization Lagoons. This
Symposium was conducted at Kansas
City, Missouri, August 1-5, 1960
by Region VI, Public Health Service,
at the request of the 10 states of the
Missouri Basin. I believe the
Kansas City office of FWPCA still
has a limited supply of this publica-
tion, and that it can be made
available upon request.
Poor maintenance may lead to emergent
vegetation, which in turn can lead to
mosquito propagation. The major
species produced in lagoons are culex
tarsalis and culex pipiens -- both
primary vectors of encephalitis.
Mosquitoes do not propagate in a
properly maintained lagoon.
This outline was prepared by G. J. Hopkins,
Director, Water and Pollution Control
Depts., City of Kansas City, MO 64106.
22-5
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SAMPLING IN WATER QUALITY STUDIES
I INTRODUCTION
A Objective of Sampling
1 Watejvquality characteristics are not uni-
form from one body of water to a another,
from place to place in a given body of
water, or even from time to time at a
fixed location in a given body of water.
A sampling program should recognize
such variations and provide a basis for
interpretation of their effects.
2 The purpose of collection of samples is
the accumulation of data which can be
used to interpret the quality or condition
of the water under investigation. Ideally,
the sampling program should be so de-
signed that a statistical confidence limit
may be associated with each element of
data.
3 Water quality surveys are undertaken
for a great variety of reasons. The
overall objectives of each survey greatly
influence the location of sampling
stations, sample type, scheduling of
sample collections, and other factors.
This influence should always be kept in
mind during planning of the survey.
4 The sampling and testing program should
be established in accordance with princi-
ples which will permit valid interpretation.
a The collection, handling, and testing
of each sample should be scheduled
and conducted in such a manner as
to assure that the results will be
truly representative of the sources of
the individual samples at the time and
place of collection,
b The locations of sampling stations
and the schedule of sample collections
for the total sampling program should
be established in such a manner that
the stated investigational objectives
will be met, and
c Sampling should be sufficiently
repetitive over a period of time to
provide valid data about the condition
or quality of the water.
B Sample Variations
Interpretation of survey data is based on
recognition that variations will occur in
results from individual ssfrnples. While
it is beyond the scope of this discussion
to consider the implications of each in
detail, the following can be identified as
factors producing variations in data and
should be considered in planning the sam-
pling program.
1 Apparent variations
a Variations of a statistical nature,
due to collection of samples from
the whole body-of water; as con-
trasted with examination of all the
water in the system.
b Variations due to inherent precision
of the analytical procedures.
c Apparent variations are usually
amenable to statistical analysis.
2 True differences
a Variations of a cyclic nature
Diurnal variations, related to alter-
nating periods of sunlight and
darkness.
Diurnal variations related to waste
discharges from communities.
WP. SUR. sg. la. 6. 66
24-1
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Sampling in Water Quality Studies
Seasonal variations, related to
temperature and its subsequent
effects on chemical and biological
processes and interrelationships.
Variations due to tidal influences,
m coastal and estuanne waters.
b Intermittent variations
Dilution by rainfall and runoff.
Effects of irregular or intermittent
discharges of wastewater, such as
"slugs" of industrial wastes.
Irregular release of water from
impoundments, as from power
plants
c Continuing changes in water quality
Effects downstream from points of
continuous release of wastewater.
Effects of confluence with other
bodies of water.
Effects of passage of the water
through or over geological forma-
tions of such chemical or physical
nature as to alter the characteristics
of the water
Continuing interactions of biological,
physical, and chemical factors in
the water, such as in the process of
natural self-purification following
introduction of organic contaminants
in a body of water.
II LOCATION OF SAMPLING STATIONS
A The Influence of Survey Objectives
Much of the sampling design will be
governed by the stated purpose of the
water investigation As an example of
how different objectives might influence
sampling design, consider a watercourse
with points A and B located as indicated
in Figure 1
A
X X
~Z > B
flow
Figure 1
Point A can be the point of discharge of
wastes from Community A Point B can
be any of several things, such as an intake
of water treatment plant supplying Com-
munity B, or it might be the place where
the river crosses a political boundary, or
it may be the place where the water is
subject to some legitimate use, such as
for fisheries or for recreational use.
1 Assume that the objective of a water
quality investigation is to determine
whether designated standards of water
quality are met at a water plant intake
at Point B In this case, the objective
only is concerned with the quality of the
water as it is available at Point B
Sampling will be conducted only at
Point B.
2 Alternately, consider that there is a
recognized unsatisfactory water quality
at Point B, and it is alleged that this
is due to discharges of inadequately
treated wastes, originating at Point A
Assume that the charge is to investigate
this allegation.
In this case the selected sampling sites
will include at least three elements
a At least one sampling site will be
located upstream from Point A, to
establish base levels of water quality,
and to check the possibility that the
observed conditions actually originated
at some point upstream from Point A.
b A site or sites must be located down-
stream from Point A Such a site
should be downstream a sufficient
distance to permit adequate mixing in
the receiving water.
c Sampling would be necessary at Point
B in order to demonstrate that the
water quality is in fact impaired, and
that the impairment is due to influences
traced from Point A
24-2
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Sampling in Water Quality Studies
B Hydraulic Factors
1 Flow rate and direction
a In a survey of an extended body of
water it is necessary to determine
the rate and direction of water move-
ment influences selection of sam-
pling sites. Many workers plan
sampling stations representing not
less than the distance water flows
in a 24-hour period Thus, in
Figure 1, intervening sampling
stations would be selected at points
representing the distance water
would flow in about 24 hours
b In a lake or impoundment direction
of flow is the major problem influenc-
ing selection of sampling stations.
Frequently it is necessary to estab-
lish some sort of grid network of
stations in the vicinity of the sus-
pected sources of pollution.
c In a tidal estuary, the oscillating
nature of water movement will re-
quire establishment of sampling
stations in both directions from
suspected sources of pollution.
2 Introduction of other water
a In situations in which a stream being
studied is joined by another stream
of significant size and character,
sampling stations will be located
immediately above the extraneous
stream, in the extraneous stream
above its point of juncture with the
main stream, and in the main
stream below the point of juncture.
b Similar stations will be needed with
respect to other water discharges,
such as from industrial outfalls,
other communities, or other instal-
lations in which water is introduced
into the main stream.
3 Mixing
a Wherever possible, one sampling
point at a sample collection site is
used in stream surveys. This
usually is near the surface of the
water, in the main channel of flow
b In some streams mixing does not
occur quickly, and introduced water
moves downstream for considerable
distances below the point of con-
fluence with the main streams.
Example Susquehanna River at
Harrisburg, where 3 such streams
are recognizable in the main river.
Preliminary survey operations
should identify such situations.
When necessary, collect separate
samples at two or more points
across the body of water.
c Similarly, vertical mixing may not
be rapid. This is noted particularly
in°tidal estuaries, where it may be
necessary to make collections both
from near the bottom and near the
surface of the water.
d Collection of multiple samples from
a station requires close coordination
with the laboratory, in terms of the
number of samples that can be
examined Some types of samples
may be composited The decision
must be reached separately for each
type of sample.
C Types of Analytical Procedure
1 Samples collected for physical, chemi-
cal, and bacteriological tests and
measurements may be collected from
the same series of sampling stations.
2 Sampling stations selected for biological
(ecological) investigation require
selection of a series of similar aquatic
habitats (a series of riffle areas, or a
series of pool areas, or both). The
sites used by the aquatic biologist may
or may not be compatible with those
used for the rest of the survey Accord-
ingly, in a given stream survey, the
stations used by the aquatic biologist
usually are somewhat different from the
stations used for other examinations.
24-3
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Sampling in Water Quality Studies
D Access to Sampling Stations
For practical reasons, the sampling site
should be easily reached by automobile if
a stream survey, or by boat if the survey
is on a large body of water. Highway
bridges are particularly useful, if the
sample collector can operate in safety
III FACTORS IN SCHEDULING OF SAMPLING
PROGRAMS
A Survey Objectives
B Time of Year
1 In short-term water quality investiga-
tions, particularly in pollution
investigations, there often is need to
demonstrate the extreme^ of pollution
effects on the aquatic environment.
For this reason, many short-term
surveys are conducted during the
warmer season of the year, at such
times as the water flow rate and
volume is at a minimum and there is
minimum likelihood of extensive
rainfall.
2 In a long-term investigation, sampling
typically is conducted at all seasons
of the year.
C Daily Schedules
As shown m an introductory paragraph,
water quality is subject to numerous
cyclic or intermittent variations. Sched-
uling of sample collections should be de-
signed to reveal such variations
1 In short-term surveys it is common
practice to collect samples from each
sampling site at stated intervals through
the 24-hour day, continuing the program
for 1-3 weeks. Sampling at 3-hour
intervals is preferred by many workers,
though practical considerations may re-
quire extension to 4- or even 6-hour
intervals.
2 In an extended survey there is a ten-
dency to collect samples from each
site at not more than daily intervals,
or even longer. In such cases the
hour of the day should be varied through
the entire program, in order that the
final survey show cyclic or intermittent
variations if they exist.
3 In addition, sampling in tidal waters
requires consideration of tidal flows.
If samples are collected but once daily,
many workers prefer to make the col-
lections at low slack tide.
4 In long-term or any other survey in
which only once-daily samples are
collected, it is desirable to have an
occasional period of around-the-clock
sampling.
IV IDENTIFICATION OF SAMPLING SITES
A River Mile System
The FWPCA method of identifying points
on a water course is by counting river
miles from the mouth (or junction with a
larger stream) back to the source. This
should not be confused with other systems,
such as those in which the river mile is
started at the source of the stream and
proceeds to the mouth of the stream or
confluence with another body of water.
B STORET System
The STORET System is a computer-oriented
data processing system used by FWPCA for
storage, retrieval, and analysis of water
quality data collected by federal, state,
local, and private agencies.
The system includes a complex system -
based on the river mile system - for
identifying sampling locations on all rivers
and streams in the United States. A recent
addition to the system introduces a location
procedure based on geographic coordinates,
this procedure is especially adapted to
location of sampling stations in large bodies
of water such as lakes and impoundments.
24-4
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Sampling in Water Quality Studies
Not all locations have been coded at this
time, although the coding systems have
been established. The interested worker
should consult Public Health Service Publi-
cation No. 1263, "The Storage and Retrieval
of Data for Water Quality Control. " 1963.
V SAMPLE COLLECTION
A Types of Samples
1 "Grab" sample - a grab sample is usually
a manually collected single portion of the
wastewater or stream water. An analysis
of a^grab sample shows the concentration
of the constituents in the water at the time
the sample was taken.
2 "Continuous" sample - when several points
are to be sampled at frequent intervals or
when a continuous record of quality at a
given sampling station is required, an
automatic or continuous sampler may be
employed.
a Some automatic samplers collect a
given volume of sample at definite time
intervals, this is satisfactory when the
volume of flow is constant.
b Other automatic samplers take samples
at variable rates in proportion to chang-
ing rates of flow. This type of sampler
requires some type of flow measuring
device.
3 "Composite" sample - a composite
sample is the collection and mixing
together of various individual samples
based upon the ratio of the volume of
flow at the time the individual samples
were taken to the total cumulative
volume of flow. The desired composite
period will dictate the magnitude of the
cumulative volume of flow. The more
frequently the samples are collected,
the more representative will be the
composite sample to the actual situa-
tion. Composite samples may be
obtained by
a Manual sampling and volume of flow
determination made when each sam-
ple is taken.
b Constant automatic sampling (equal
volumes of sample taken each time)
with flow determinations made as
each sample is taken.
c Automatic sampling which takes
samples at pre-determined time
intervals and the volume of sample
taken is proportional to the volume
of flow at any given time.
B Type of Sampling Equipment
1 Manual sampling
a Equipment is specially designed
for collection of samples from the
bottom muds, at various depths,
or at water surfaces. Special
designs are related to protection of
sample integrity in terms of the
water characteristic or component
being measured.
b For details of typical sampling equip-
ment used in water quality surveys,
see outlines dealing with biological,
bacteriological, and chemical tests
in this manual.
c Manual sampling equipment has
very broad application in field work,
as great mobility of operation is
possible, at lower cost than may be
possible with automatic sampling
equipment.
2 Automatic sampling equipment
Automatic sampling equipment has
several important advantages over
manual methods. Probably the most
important consideration is the reduction
in personnel requirements resulting
from the use of this equipment. It
also allows more frequent sampling
than is practical manually, and elimi-
nates many of the human errors in-
herent in manual sampling
Automatic sampling equipment has
some disadvantages. Probably the
most important of these is the tendency
of many automatic devices to become
24-5
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Sampling in Water Quality Studies
clogged when liquids high in solids are
being sampled Individual portions of
composite samples are usually quite
small which may in some cases be
disadvantageous. In using automatic
samplers, sampling points are fixed,
which results in a certain loss of
mobility as compared to manual
methods.
Automatic sampling equipment should
not be used indiscriminately, some type:
of samples - notably bacteriological,
biological, and DO samples - should
not be composited. In cases of doubt,
the appropriate analyst should be
consulted.
a Compositing samplers
1) Jar and tube sampler - this type-
samples effectively when flow
is nearly constant. As water
drains from the upper carboy,
the vacuum created syphons
waste into the lower one. The
rate-of-flow is regulated by the
pinch clamp to fill the lower
carboy during the sampling
period. (See Figure 2 )
€®ROITDG9QD@QPS MWGJK
WATER
WASTE SAMPLE SCREW CLAMP
WASTE STREAM
C MUST BE GREATER THAN A+B
Figure 2
24-6
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Sampling in Water Quality Studies
2) Scoop type
a) Rotating scoop
This device consists of a
power driven scoop mounted
upstream from a weir The
scoop is so designed and
mounted that the sample vol-
ume grabbed on each rotation
of the scoop is proportional to
the flow, as governed by the
head on the weir. The scoop
may be rotated at a constant
speed or timed to sample
at fixed time intervals.
b) Revolving wheel with cups
(Figure 3)
This device consists of a
power driven wheel or disc
mounted upstream from a
weir. A number of freely
suspended buckets are mount-
ed at varying distances from
the axis so that increased
flow will cause more buckets
to be filled, thereby giving a
sample proportionate to flow.
Both this device and the
rotating scoop sampler can,
of course, be used for non-
proportionate sampling.
c) Bucket elevators
This device may consist of a
single bucket alternately
lowered into and raised out of
the waste stream, or it may
consist of a series of buckets
on an endless chain passing
through the waste stream. In
either case, it will include a
tripping mechanism to cause
the bucket or buckets to spill
into a sampling funnel. Both
types may be operated contin-
uously or timed for intermittent
operation. This method is not
well adapted to proportionate
sampling.
Figure 3
WHEEL WITH BUCKETS
3 Pumps
a) Chemical feed pumps have
been found useful for sampling,
because of their ability to
meter out small doses of
liquids. A timing mechanism
may be used to make the pump
run for longer periods during
heavy flow, thereby allowing
collection of the sample in
proportion to flow These
pumps are usually provided
with adjustable stroke and
variable speed features which
allow variation of the volume
of sample being pumped.
Figure 4 illustrates a battery
Operated pump.
b) Automatic shift sampler
(Figure 5 )
Figure 5 shows the automatic
shift sampler. It consists
first of a Randolph or other
"squeegee-" type pump unit
24-7
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Sampling in Water Quality Studies
The 2-rpm gear motor drives
the pump at between 1 and 2
rpm through the spring-loaded
adjustable-pitch pulley and
adjustable motor-base arrange-
ment.
We use 1/8-in. (. 32-cm) ID
or l/4-in. (. 64-cm) ID
polyethylene tubing for sam-
ple intake from the waste
stream. The sample flow is
delivered to the distributor
via a 3/16-in. (. 48-cm) ID
Tygon tube which is supported
loosely by a wire attached to
the framework.
Operation of the distributor is
very simple. The 1-rpm clock
motor powers the chain-and-
sprocket drive which turns a
threaded bolt. Rotation of the
bolt moves the discharge tube
down the plastic trough at a
rate equal to one division
every eight hours. With the
10 sample-jar receivers the
timer can be set on Friday,
and the 9 week-end shift
samples can be picked up on
Monday.
Figure 4
BATTERY OPERATED PUMP
4) Solenoid-valve arrangements
A solenoid valve employed in
connection with a timing device
may be used for withdrawing
waste from a pipe under pressure.
Used in connection with a pump
such devices may be employed in
sampling free flowing streams.
(See Figures 6 and 7.)
SOLENOID VALVt
(INSTALL 10 U NOT
TO ACT AS TKAPI
ACCUMULATING tank
Figure 6
PUMP - SOLENOID VALvE - TIMER
TYPE SAMPLER
5) Vacuum operated
In its simplest form, the vacuum
is created by a suitably mounted
siphon. It collects the sample
at a uniform rate and is not
suitable for use when proportional
sampling is required.
24-8
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Sampling in Water Quality Studies
Position of Senpi*
I Tuft# OtBChorflnf re
I Centering v«at«i.
RufiOtr Tubing Joint
-SOLENOID PUSMCA
—' No* nvol Potilion of
SmeltftQ Tuftf RtttfMi|
to S««tr
Return Ptpo
Sompi* Collecting Vtttti
Figure 7
PUMP - SOLENOID-DIVERTER - TIMER
TYPE SAMPLER
6) Air vent control
This type of device is illustrated
in Figure 8. The rate of sample
c collection is controlled by the
bubbling mechanism. It is not
suitable for use when proportion-
ate sampling is required.
vuyt HAMOU
FROM 9AMPLCR
TO BUBBLER —
OUT
>LR OUT
uxrin *'
MM IB' LOMS
Figure 8
AIR RELEASE TYPE SAMPLER
7) Drip sampler
Two types of this device are
illustrated in Figures 9 and 10.
Both devices are simple methods
of obtaining a composite sample
at a fairly constant rate.
WIRE ROD SOLDERED
TO FUNNEL AND BENT
TO PASS THROUGH
WATER JET
WASTES
FROM SEWER
FUNNEL WITH
NARROW SLOT
CUT IN SIDE
Figure 9
FUNNEL AND ROD DIVERTER
OLASS
r^S
Figure 10
DRIP TUBE SAMPLERS
24-9
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Sampling in Water Quality Studies
b Continuous recording equipment
Instruments have been developed
which provide direct measurement
of temperature, pH, conductivity,
color, and dissolved oxygen. Such
instruments may be equipped for
continuous recording Instruments
of this type are quite expensive and
their installation is often difficult.
They are best adapted to permanent
installations, although good portable
non-recording instruments are
available for the measurement of
temperature, pH, and conductivity.
VI SOME CONSIDERATIONS IN SAMPLING
OPERATIONS
All procedures in care and handling of sam-
ples between collection and the performance
of observations and tests are directed toward
maintaining the reliability of the sample as
an indication of the characteristics of the
sample source.
A Sample Quantity
1 Samples for a series of chemical
analyses requires determination of the
total sample volume required for all
the tests, and should include enough
sample in addition to provide a safety
factor for laboratory errors or acci-
dents. Many workers collect about
twice the amount of sample actually
required for the chemical tests. As
a rule of thumb, this is on the order
of 2 liters.
2 Bacteriological samples, in general,
are collected in 250 - 300 ml sterile
bottles, approximately 150 - 200 ml of
samples is adequate in practically all
cases.
B Sample Identification
1 Sample identification must be main-
tained throughout any survey It is
vital, therefore, that adequate records
be made of all information relative to
the source of the sample and conditions
under which the collection was made.
All information must be clearly under-
standable and legible
2 Every sample should be identified by
means of a tag or bottle marking,
firmly affixed to the sample bottle.
Any written material should be with
indelible marking material
3 Minimum information on the sample
label should include identification of
the sample site, date and time of col-
lection, and identification of the
individual collecting the sample.
4 Supplemental identification of samples
is strongly recommended, through
maintenance of a sample collection
logbook. If not included on the sample
tag (some prefer to duplicate such infor-
mation) the logbook can show not only
the sample site and date and hour of
collection, but also the results of any
tests made on site (such as temperature,
pH, dissolved oxygen). In addition, the
logbook should provide for notation of
any unusual observations made at the
sampling site, such as rainfall, direc-
tion and strength of unusual winds, or
evidence of disturbance of the collection
site by human or other animal activity.
C Care and Handling of Samples
1 As a general policy, all observations
and tests should be made as soon as
possible after sample collection.
a Some measurements require perform-
ance at the sampling site, such as
temperature, light intensity (if
determined), flow^rate, etc.
b Some tests are best made at the
sampling site because the procedures
are simple, rapid, and of acceptable
accuracy. This may include such
determinations as pH and conductivity.
c Some additional determinations, such
as alkalinity, hardness, dissolved
24-10
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Sampling in Water Quality Studies
oxygen, and turbidity may be made
in the field, provided that ease, con-
venience, and reliability of results
are acceptable for the purposes of
the study.
2 Samples to be analyzed in the laboratory
require special protection to assure that
the quality measured in the sample repre-
sents the condition of the source. Many
samples, especially those subjected to
biological analysis, require special pre-
servation, protection, and handling pro-
cedures. In case of doubt, the appropriate
analyst should be consulted. Most com-
mon procedures for sample protection
include.
a Examination within brief time after
collection.
b Temperature control.
c Protection from light.
d Addition of preservative chemicals.
Applications of these sample protective
procedures are along the following
lines
3 Early examination of sample
Applicable to all types of samples.
4 Temperature control
a All biological materials for examina-
tion in a living state should be iced
between collection and examination.
b Bacteriological samples, according
to "Standard Methods" should be
maintained at the same temperature
as the source of the sample between
collection and starting the laboratory
tests. Most survey workers, how-
ever, continue to ice samples and
start laboratory tests within 6 hours
after collection.
c Chemical samples often require
icing.
Samples for dissolved oxygen can
be maintained several hours if kept
iced, and protected from the light.
BOD samples can be held several
hours in an iced condition.
Quick freezing will permit retention
of many samples for up to several
months prior to laboratory examina-
tion.
5 Protection from light
a Any constituent of water which may
be influenced by physiochemical
reactions involving light should be
protected. DO samples brought to
the iodine stage, for example, should
be protected from light prior to
titration.
b In addition, any water constituent
(such as dissolved oxygen) which
may be influenced by algal activity
should be protected from light.
6 Addition of chemical preservatives
a Bacteriological samples never
should be "protected" by addition
of preservative agents. The only
permissible chemical additive is
sodium thiosulfate, which is used
to neutralize free residual chlorine,
if present.
b Samples for biological examination
should be protected by chemical
additives only under specific
direction of the principal biologist
in a water quality study. Limited
applications of chemical preserva-
tives are discussed m the biology
outlines in this manual.
c For chemical tests, preservatives
are useful for a number of water
components. The following examples
are cited:
Nitrogen and phosphorus analyses
The addition of 1 ml concentrated
H2SO4/liter of sample will retard
biological activity, which otherwise
might alter the concentration of
these constituents. However, it
should be noted that some procedures
for these determinations will require
24-11„
-------
Sampling in Water Quality Studies
subsequent neutralization of the
sample.
Metals The addition of 1 - 5 ml of
acid (HC1, HNO3, or H2SO4) pre-
vents precipitation of the metal in
the container. The choice of acid
depends on what other analyses are
to be made on the sample (e. g. HC1
would not be used to preserve a sam-
ple which later will be analyzed for
chlorides).
COD and ABS. Addition of 1 ml
sulfuric acid per liter of sample is
suggested.
In general, samples requiring re-
tardation of biological activity can
be temporarily preserved by addi-
tion of chloroform, tests should be
run as soon as possible, however.
Determination of ratio of volatile
to suspended solids can be delayed
up to 6 months if 2% formaldehyde is
added.
Cyanide determinations may be
delayed temporarily through addition
of alkali to the sample. A few
pellets of sodium hydroxide are
sufficient.
Sulfide analysis may be delayed up
to as much as 6 months by addition
of 2 ml/liter of sample of 2N solu-
tion of zinc acetate.
Phenol analysis can be delayed
temporarily by acidification to below
pH 4. 0 with phosphoric acid and
preservation with 1 gram CUSO4
per liter of sample.
REFERENCES
1 Standard Methods for the Examination of
Water, Sewage and Industrial Wastes.
12th Ed. A. P. H.A. 1965.
2 Planning and Making Industrial Waste
Surveys. Ohio River Valley Water
Sanitation Commission.
3 Industry's Idea Clinic. Journal of tfre
Water Pollution Control Federation.
April, 1965.
This outline was prepared by H. L. Jeter, Acting
Chief and P. F. Atkins, Jr., Former Sanitary
Engineer, FWPCA Training Activities, SEC.
24-12
-------
SAMPLING IN TREATMENT PLANT OPERATIONS
I Another outline considered sampling for
water quality in surface waters. The labora-
tory analyst will be involved in sampling and
analysis in surface waters and in the treat-
ment plant. The same principles apply but
the routines are likely to be different because
it is impossible to select a routine applicable
for biological, chemical and physical tests
for every flow, condition, or facility. Each
situation must be considered in terms of test
objectives, site selection, available man-
power, sample and test variables.
A The sampling and analysis program are
expected to provide an estimate of one
or more important variables that can be
used as a guide in operations control.
1 The sample is expected to be repre-
sentative of materials included at a
particular location, at a particular
time (or interval), at a particular
stage of some process.
2 The analysis can not correct for
sampling inconsistencies.
3 Sampling variability depends in part
upon mixing dynamics at or prior to
the sampling site and upon the charac-
teristics of the material.
4 Variability in sampling can be estimated
by separate sample analysis (catch or
grab samples) taken at various points
on a dimensional reference of cross
section (surface and depth) or at one
or more points at various intervals
of time.
5 A true average ideally would include
analysis of the entire sampling mass
according methodologies giving pre-
cise and accurate results. This rarely
can be achieved or would be desired,
hence, we sample to arrive at a practi-
cal compromise of effort and information.
a The average can be approximated
in terms of cross section and time
from results on a composite of
separate samples.
b A more valid estimate of the average
results are possible when the indi-
vidual samples are proportioned to
flow or mass in the composite.
II Treatment operations require sampling
and analysis for two primary objectives:
A Record results are essential to show what
entered the plant and what left the plant
in terms of concentration, condition, and
character.
B Control of operations involves optimization
of conditions favoring better ratios of
benefit per unit of time, space, cost or
effort.
Ill The sampling program should be a cooper-
ative effort among supervisors, operators,
samplers, analysts and other interested
parties. It should be checked for validity
and applicability of information obtained and
reviewed periodically or whenever conditions
may have changed.
A Each installation is limited in manpower
skills and equipment, some more than
others. A compromise must be reached
that will provide essential information for
that particular situation.
B Each part of the team should be clearly
aware of what samples to obtain, why,
where, when and how they are to be used.
The operation must be scheduled for
smooth working arrangements.
1 The sampler must be aware that he is
responsible for the starting point in
a series consisting of sampling,
PC. 3. 10. 67
25-1
-------
Sampling in Treatment Plant Operations
determination, reporting, and use of
the derived information.
a Sampling must follow prescribed
location, time and technique schedules
agreed upon beforehand and tested
for validity in line with operation
objectives.
b Each sample must be clearly identi-
fied according to the designated
system in terms of location, time,
type, etc. Unusual conditions that
may affect results should be noted
on the identification tag. Marked
changes in sample characteristics
should be reported promptly to
proper authority for possible cor-
rective action.
c Samples should be stored under
conditions minimizing changes
before analysis.
IV Treatment plant samples involve a high
degree of variability and changes in charac-
teristics within the plant.
A The influent samples are subject to greater
variability than samples from any other
part of the plant or the receiving water.
1 The influent flow contains a variety of
materials under unstable conditions.
a Certain components are readily
separated from the flow because of
size, density, volatility or other
characteristics.
b Highly putrescible material may be
stabilized rapidly in process.
2 Geographic factors control rate of flow
to the plant and mixing or stabilization
en route. A given slug discharge may
not be detectable if it enters the collec-
tion system at a point where it can be
dispersed among other contributions.
a Smaller collection systems emphasize
both variability and effects of single
contributors.
3 A given channel flow may include solids
movement along the bottom and floatable
materials at the surface. A sample of
this flow contains variable proportions
of both depending upon turbulence at
the sampling site.
4 Contributing population activities are
scheduled by working, eating, sleeping,
weather, TV, and other influences.
Wastewater load varies accordingly
with the time of the day, week or month.
B The plant functions as an equilization basin
as well as a processing facility.
1 A given slug discharge is dispersed
among liquids already in process.
2^ It may require several hours to traverse
various process units. Plant perform-
ance sampling at the inlet and outlet
at a given time is likely to represent
different process loads or conditions.
3 Changing conditions within the plant
affect determinability of certain analy-
tical criteria in process.
a An influent and effluent BOD involve
different progressions.
V Treatment plant sampling preferably
should be designed to show what has been
done during the operation and what remains
to be done.
A Integrity of the sampling program is deter-
mined by the comparisons between actual
performance and reported performance.
1 Treatment plant loading includes
that into process
2 The discharged flow includes treated,
by-passed, or process return flows.
3 Plant achievement reflects the differ-
ence in material balance among incoming
and outgoing process water contributions
of nutrients, oxygen demand, solids or
other criteria.
This outline was prepared by F. J. Ludzack,
Chemist, National Training Center, FWQA,
Cincinnati, OH 45226.
25-2
-------
DETERMINING EFFICIENCY OF SETTLING TANKS AND CLARIFIERS
I INTRODUCTION
A The need for examination of sewage as it
enters and leaves sedimentation tanks
varies from plant to plant. In deciding
which tests are essential, the operator
must take into account the treatment units
which follow, such as trickling filters,
aeration tanks, intermittent sand filters,
and sludge digestion and dewatering facilities,
B Where the effluent is discharged to receiving
waters without further treatment, the
operator must select tests which will
measure the impact on the stream.
H TESTS FOR DETERMINING EFFICIENCY
A Suspended and Settleable Solids
1 Tests for settleable and suspended solids
are used to measure the effectiveness of
sedimentation. These tests should be
made daily on composited samples at
large plants and at least twice weekly at
smaller plants where laboratory work is
conducted.
2 Samples should be taken of the influent
and effluent of the tank at parts where
the sewage is well mixed.
3 Test results indicate the clarity of the
effluent and the loading of suspended
matter on the receiving waters or the
biological treatment units which may
follow. They also indicate the quantity
of sludge to be treated and disposed of.
4 Efficiency of solids removal by sedi-
mentation can be calculated from
influent and effluent data.
B Biochemical Oxygen Demand
1 The five-day biochemical oxygen demand
test provides a good measurement of
sewage strength.
2 Tests on composite samples of influent
and effluent should be made daily and
never less frequently than twice weekly,
even in small plants.
3 Tests on the tank effluent provide a
good measure of the strength and
quantity of the organic loading imposed
on subsequent biological processes or
on the receiving waters.
Ill TEST PROCEDURES
A Settleable Solids Test
1 Sampling - Catch samples at period of
maximum flow and if possible allow for
the lag in time equal to the flow-through
period of the settling tank.
2 Equipment - Two Imhoff cones, one for
influent and one for effluent. These
are large glass cones of one-liter
capacity, the lower ends of which are
graduated in milliliters (ml). They
should be cleaned with strong soap and
hot water, using a brush. Wetting of
the cone with water before use helps to
prevent adherence of the solids to the
sides. A wooden rack or shelf should
be provided to hold the cones.
3 Procedure
a A measured quantity of well-mixed
sample, usually one liter, is gently
poured into the cone and allowed to
stand for a total period of one hour.
b After the sample has stood forty-five
minutes, gently rotate the cone
between the hands so as to loosen the
solids that adhere to the sides.
c Allow to settle fifteen minutes longer.
d Read from the graduations the volume
of solid material deposited in the
cone making allowances for any
PC. WAS. 6. 11. 68
26-1
-------
Determining Efficiency of Settling Tanks and Clarifiers
unfilled portions of the cone below
the level of the settled solids.
4 Results are expressed as ml of solids
per liter which settled in one hour.
ml of solids X
1000
ml of sample
ml of settleable solids per liter
If the samples represent the influent and
effluent of a tank, the efficiency of the
tank may be found.
ml of solids per
liter of influent
(-)
ml of solids per
liter of effluent
ml of solids per liter of influent
X 100
percent of settleable solids removed
B Suspended Solids Test
1 Sampling - The same samples that were
collected for the settleable solids test
should be used for this test, or preferably,
an integrated sample adequately
refrigerated.
2 Equipment - Gooch crucibles, a filter
flask with fittings, aspirator filter pump,
drying oven, desiccator, analytical
balance with weights, graduated cylinder
(100 ml), washed and ignited medium
asbestos fibre, and a gas burner with
tripod and triangles or an electric
muffle furnace.
3 Procedure
a Prepare a suspension of 15 grams of
medium asbestos fibre in 1000 ml of
distilled water and pour a portion
through the Gooch crucible in the
filter flask to make a mat about one-
eighth inch thick.
c Wash with 100 ml distilled water.
d Dry crucible with mat in oven at
103OC.
e Ignite crucible and mat in muffle
furnace or over gas burner.
f Cool in desiccator and weigh.
g Again place crucible in filter flask
and pour a measured amount of the
well-mixed sample into the crucible
and filter it through. Filtration is
faster if sample is added in small
increments. For settled sewage or
plant effluents, larger portions
should be used.
h Rinse the graduated cylinder with
distilled water and pour through the
filter.
i Dry the crucible in the oven for one
hour at 103°C.
j Cool in desiccator and weigh.
4 Results are expressed as parts per
million (ppm). The difference between
the weight of the crucible before
filtering and the weight of the crucible
after filtering is the weight m grams
of the total suspended solids.
weight of suspended 1.000, 000
solids in grams ml of sample
ppm total suspended solids
If the samples represent the influent
and effluent of a tank, the efficiency
of removal of suspended material can
be calculated.
Carefully remove the mat with a
spatula or tweezers. Invert and
replace in the Gooch crucible.
mg of suspended solids ^ ^ mg of suspended solids
per liter of influent per liter of effluent
mg of suspended solids per liter of influent
X 100 = percent of suspended solids removed
26-2
-------
Determining Efficiency of Settling Tanks and Clanfiers
C BOD
1 Sampling - The samples which represent
the influent and effluent will require
dilution depending upon the sewage
strength.
2 Equipment and procedures for conducting
the test are considered in subsequent
outlines.
3 Efficiency of BOD removal in the settling
tanks can be calculated from the influent
and effluent data.
REFERENCES
Manual of Instruction for Treatment Plant
Operators, Distributed by Health
Education Service, P.O. Box 72 85,
Albany, New York 12224.
Operation of Wastewater Treatment Plants,
WPCF Manual of Practice #11, Water
Pollution Control Federation, Washington,
D.C., (1966).
This outline was prepared by D. S. May,
Microbiologist, FWPCA Training A ctivities,
PNWL.
26-3
-------
TESTING ASA TOOL FOR DIGESTER OPERATIONS
I NEED FOR LABORATORY CONTROL
A Sludge digestion is essentially a biochemical
process and a rather involved one. Its
effective management and control require
frequent observations of the raw, inter-
mediate, and end products unless the
facilities greatly exceed present needs and
all other plant processes are so well
regulated that even poor operation of the
digester would overcome these deficiencies.
Such a combination of circumstances
seldom exists.
B In deciding what measurements and tests
are essential and desirable for his needs,
the operator must take into account the
variability of the quantity and quality of the
raw sludge, the kind and number of units
in the digester system, and the acceptable
range of quality of the digested sludge and
supernatant. If sludge gas is utilized for
heat or power, its volume and components
become important.
C When satisfactory digestion is in progress,
the following measurements and tests are
most useful to determine loading on the
digester units, departures from normal
values, progress of digestion, quality of
digested sludge and supernatant, effect on
other plant units, trends in over-all
performance, and reserves for unusual
circumstances and future growth
1 Sludge in digester
a Temperature
b pH
c Percent volatile matter
d Volatile acids
e Bicarbonate, alkalinity, ammonia,
or other alkalinity
f Physical characteristics
g Quantity transferred to other digesters
h Gas production
1 Gas components
2 Digested sludge withdrawn
a Physical characteristics
b Volume removed
c Total and volatile solids
d pH
3 Supernatant
a Volume removed
b pH
c Volatile acid/alkalinity ratio
d Suspended solids
e BOD
II DIGESTING SLUDGE
A Samples and measurements of digesting
sludge should be analyzed with sufficient
frequency to determine
1 The progress of digestion
2 Reasons for unusual performance
3 When to withdraw sludge
4 Needed changes in controls
B Sampling of Sludge
1 As in the case of sewage, the value of
sludge analyses depends largely upon
the accuracy of sampling. Thus it is
necessary to observe strict pre-
cautions in the selection of sampling
PC. WAS. 5. 11.68
28-1
-------
Testing as a Tool for Digester Operations
points and methods of sampling to insure
the collection of representative samples
at all times.
2 To collect samples of sludge from
different depths in a tank, a sampling
apparatus can be used that is made of
cast iron or brass weighted with lead.
It can be lowered into the tank by a link
chain which carries markings showing
the various depths. The apparatus is
fitted with valves operated by a cord.
A pull on the cord at the desired depth
opens the valves and the sludge flows
in at the bottom while air escapes at
the top.
3 A wide-mouth stoppered bottle attached
to the end of a pole can also be used.
The bottle is pushed to the desired depth
and the stopper removed by means of an
attached cord.
4 Many sludge digesters are equipped with
sampling taps at various depths. Care
must be taken to insure that the lines
are freed of accumulated sludge before
the sample is taken.
C Temperature
1 The temperature of the digesting sludge
should be recorded so that both short -
and long-term fluctuations and trends
may be observed and recorded at various
levels in the unit.
2 Severe fluctuations in temperature may
drastically affect the operation of the
digester.
D pH
1 The pH is a valuable indicator of
conditions but volatile acid/alkalinity
relations are more valuable for control
purposes.
2 The organisms which bring about
anaerobic decomposition of organic
materials have an optimum activity
pH range of from 6. 8 to 7. 2 usually
signifying an acid/alkalinity ratio less
than 0.5/1.0.
3 Low pH indicates excessive production
of organic acids.
4 High pH indicates insufficient feeding
or essentially complete digestion.
5 Ordinarily, the acid/alkalinity ratio of
the digesting sludge need not be
measured more often than once weekly
unless unstable or unfavorable conditions
are developing in the digester.
E Percent Volatile Matter
1 This is the best indicator of the progress
of digestion.
2 When the test is performed on samples
for inventory purposes, the results
provide an excellent indication of the
suitability for withdrawal for
dewatering and disposal.
3 When performed on samples of
materials transferred from the first
to the second-stage digester, the test
results give an excellent indication of
the amount of digestion required in the
second stage.
4 Ordinarily, samples would be collected
at the same frequency and for the same
reasons as outlined for pH.
F Volatile A cids
1 This test has gained in popularity in
recent years. It provides an excellent
indication of the progress of digestion
and many forecast possible future
trouble when considered as a ratio of
its alkaline equivalent.
2 It should be performed at about the
same frequency as pH.
3 During the acid stage of digestion,
volatile acids may reach levels of
several thousand mg/1, a completely
digested sludge and good supernatant
will fall well below 300.
28-2
-------
Testing as a Tool for Digester Operations
G Bicarbonate Alkalinity
1 This test is found by some operators to
be very valuable in determining the
progress of digestion.
2 Normal range for well-digested sludge
2000 to 5000 mg/1.
3 The ratio of acid to alkali is an estimate
of buffer capacity of digester contents
and resistance to changes due to rapid
or excessive loads of acid producing
feeds. A new feed rapidly contributes
to production of acids which if excessive
will cause a marked release of CC^ to
the gas phase and concurrent decrease
in alkalinity. Acid to alkalinity ratios
may be less than 0. 1/1.0 after good
digestion. A major pH decrease is
unlikely until the ratio is above 0. 5/1. 0.
H Physical Characteristics
1 Physical characteristics of digesting
sludge often give the operator a good
indication of the progress of digestion.
2 Color, texture, and odor change
markedly. Each sample collected for
laboratory tests should be examined
critically.
I Volume Transferred
1 The volume of partially or wholly
digested sludge transferred from one
digester to another or removed for
dewatering or disposal should be
estimated and recorded.
2 Falling gas production may indicate
either reduction in rate of digestion
or that digestion has proceeded to the
point where removal of digested sludge
is overdue. This frequently is the first
indication of the presence of a toxic
waste.
3 Sharp increases in gas production may
indicate over feeding, restoration of
favorable conditions after an upset, or
establishment of good operations after
startup. Acid/alkalinity relations
should be checked.
K Gas Components
1 Tests for methane, carbon dioxide,
hydrogen, and hydrogen sulfide assist
the operator in determining the cause
of poor burning characteristics of the
gas and the progress of digestion.
These tests are not performed routinely.
Information so obtained is most useful
where the gas is used in engines.
2 When the gas contains more than 40
percent carbon dioxide, it may not burn.
This high CO content is usually
accompanied Dy poor digestion and may
lead to foaming, usually resulting from
lack of proper balance among food
supply, temperature, and digestion
time. Normal CO content of the gas
ranges from 20 to 30% and is the most
common and useful check among
operating personnel.
Ill DIGESTED SLUDGE
2 This data is used to determine loadings
on other units and for calculation of
work performed by the unit from which
it is transferred.
J Gas Production
1 The quantity of gas produced during
digestion in each digester should be
measured continuously and the total
recorded daily. Departure from normal
values should be investigated and
compared with the results from other
laboratory tests and known facts for
control purposes.
A Before withdrawing sludge for dewatering
on drying beds, tests should be made to
determine completeness of digestion.
These tests are the basis for deciding
whether chemicals such as alum are
needed for conditioning as an aid to
dewatering on drying beds.
B Tests and measurements made during
withdrawal are valuable for determining
the load on the drying beds and are needed
for calculating the sludge balance in the
digester and the work done by the digestion
system.
28-3
-------
Testing as a Tool for Digester Operations
C Physical Characteristics
1 The sludge should be examined for color,
texture, and odors.
2 These are excellent indicators of the
extent of digestion.
D Volume Removed
1 The volume removed should be calculated
and recorded to assist in figuring digester
inventories and checking the amount of
total and volatile solids removed from
the system.
2 The quantity removed may be estimated
readily by calculating the volume of the
beds occupied.
E Total Solids
1 The concentration of the sludge, as
measured by total solids content,
indicates the extent to which the sludge
has given up its "bound" water. It also
indicates the extent of compaction and
separation.
2 If other tests indicate that digestion is
reasonably complete, but moisture
content is high, more time may be needed
for quiescent settling to improve
separation and compaction.
F Percent Volatile Matter
1 Cell mass initially about 90% volatile
may be digested to about 40% volatile
after extended treatment. Operating
practice usually does not result m this
magnitude of reduction. Acceptable
digestion usually results in 1/4 to 1/3
lower volatile percentage than that in
the feed.
G pH
1 The pH of the digested sludge should be
close to 7. 0.
2 Sludge with a much lower value is not
ready for dewatering.
IV SUPERNATANT
A The quality of supernatant in the digesters
should be determined before it is trans-
ferred to the other treatment processes.
If this is done, the zone of the best quality
supernatant may be located and adjustments
can be made in points of discharge,
quantities, and time periods to reduce
adverse effects in other plant units. Also,
with floating-cover tanks, supernatant
withdrawals usually can be deferred for
awhile.
B Volume Removed
1 Quantity removed should be observed
and recorded as a basis for determining
pounds of total solids and volatile
matter removed from one plant unit
and added to another.
2 Normally, it is best to remove
supernatant at a very low rate to
minimize disturbance at the source
and to minimize the effect of shock
loading on the receiving unit,
C pH and Acid/Alkalinity Relations
1 These tests have value as a guide of
digester conditions. It also helps the
operator to decide whether to change
the point of discharge so that it will
not disrupt later treatment.
2 Supernatant with an extremely low or
high pH ordinarily would not be dis-
charged to an activated sludge tank or
trickling filter except at very low rates.
3 Supernatant samples are easier to
collect and test than digested sludge,
and for this reason they are relied on
to give information on the general
state of sludge digestion,
D Suspended Solids
1 This test is useful in determining the
concentration and quantity (when
coupled with quantity of flow) of
suspended solids loading on receiving
units.
28-4
-------
Testing as a Tool for Digester Operations
This is particularly important when
the supernatant is returned to settling
and aeration tanks.
2 The concentration is indicative of the
extent of separation and compaction of
the sludge.
REFERENCES
1 Manual of Instruction for Treatment Plant
Operation, Health Education Service,
P.O. Box 7285, Albany, New York 12224.
2 Operation of Wastewater Treatment Plants,
WPCF Manual of Practice #11 and #16,
Water Pollution Control Federation,
Washington, D. C., (1966).
This outline was prepared by D.S. May,
Microbiologist, FWPCA Training Activities,
PNWL.
28-5
-------
SIGNIFICANCE OF BACTERIOLOGIC DATA
I POLLUTION
A Defined from a sanitary viewpoint, it is the
contamination of water with excreta from
the gut of warm blooded animals (humans,
domesticated animals or wild animals.)
B A comprehensive definition of pollution is
the addition of something to water which
changes its natural qualities.
Ill TYPES OF MICROORGANISMS
OCCURRING IN SURFACE WATERS
A Harmless Bacteria
1 Sanitary significance as pollution
indicators:
a Coliform group
b Fecal Streptococcus; and
The sanitary definition emphasizes only the
possible hazard of disease while the com-
prehensive definition provides for the protec-
tion of the sources of water.
II SOURCES OF BACTERIAL
POLLUTION IN WATER
c Clostridium Perfringens (anaerobic
spore producer)
2 Without sanitary significance as
pollution indicators:
a Fluorescent species.
Man-
kind
Domestic and
Wild Animals
Birds
Outdoor
privies &
septic tanks
Food
processing
plants
Bacterial Load
Organic Material (Bacterial food)
Disease Producing Species
Indicator Microorganisms
Factories
A
Surface Waters
Chemical Wastes
Industrial Wastes
Organic and Inorganic Compounds
Which May Affect Growth,
Death or Survival of Bacterial
Pollution
W. BA. 40c. 11.68
29-1
-------
Significance of Bacte nologic Data
b Chromogenic bacteria (violet, red,
yellow, green, etc.),
c Proteus group;
d Spore-producing rods (aerobic and
anaerobic),
e Achromobacter,
f Spirillium species;
g Coccus forms in chains, clumps or
packets, and
h Nuisance organisms (slime, iron
and sulfur bacteria)
B Pathogenic Species Which May be Present
1 Salmonella species (typhoid fever,
various fevers or food poisoning),
2 Shigella species (bacilliary dysentery),
3 Brucella species (Brucellosis - usually
Malta fever in man and contagious
abortion in some domestic animals),
4 Vibrio choleras (cholera in tropical
countries or backward areas),
5 Bacillus anthracis (anthrax in animals
and man);
6 Mycobacterium (human and animal
tuberculosis) tuberculosis
7 Leptospira species (Leptospirosis in
dogs, cattle, swine, rats, skunks,
opossium, raccoon and man)
8 Viruses (Viral diseases in man and
other animals),
9 Endamoeba histolytica (dysentery - more
common in hot climates),
10 Parasites (various parasitic diseases
in man and animals)
IV TYPES OF WATERBORNE DISEASES
A Epidemics of waterborne origin: explosive
outbreak of disease in large numbers of
individuals due to the accidental pollution
by fecal pathogens of a water ordinarily
safe.
B Sporadic waterborne disease- occasional
cases due to rash individuals consuming
known polluted water.
V EXAMINATION OF WATER FOR
PATHOGENIC BACTERIA
A Methods are qualitative rather than
quantitative procedures,
B Procedures fail to detect pathogenic or-
ganisms present in low densities;
C A variety of procedures and media required
for examination of each water sample,
D Consumers of water would be infected before
results of pathogenic tests were known (48
hours or longer),
E Negative test results with methods current-
ly available would not insure safe water
supply, and
F Failure to demonstrate pathogenic bacteria
would not differentiate between a safe water
(no fecal pollution) and a potentially unsafe
supply (containing fecal pollution.)
For the above reasons, routine testing of
a water for pathogenic organism would not
be applicable for the determination of safe
waters nor evaluation of water quality for
sanitation. The pathogenic microorganisms
are excluded from the group of pollution
indicators although it is their occasional
presence that produces waterborne
diseases or epidemics.
VI DEFINITION OF AN "INDICATOR
OF POLLUTION"
An "Indication of Pollution" is defined as any
microorganism which is always present in
29-2
-------
Significance of Bacteriologic Data
human or animal wastes; always found in nature
where enteric pathogenic bacteria are present,
and by its absence excludes the probability of
the presence of enteric pathogenic bacteria.
This ideal indicator has not been found. How-
ever, the coliform group is a practical and
usable indicator of pollution of water.
VII THE COLIFORM GROUP AS AN
"INDICATOR OF POLLUTION"
A Advantages
1 Always present in feces and domestic
sewage,
2 Relatively easy to detect,
3 Absence excludes the presence of enteric
pathogens in a natural water,
4 Presence indicates the possibility of
enteric pathogenic organisms appearing
at any time; and,
5 Density increases with increasing fecal
pollution.
B Disadvantages
1 Bacterial species conforming with
official definition may be derived from
sources other than fecal pollution,
2 Coliform bacteria may grow in streams,
etc., and,
3 Recency of pollution cannot be estimated
with measurable accuracy.
VIII DEFINITION OF THE COLIFORM
GROUP
The coliform group consists of aerobic and
facultative anaerobic gram-negative rods,
not producing spores and fermenting lactose
with gas production within 48 hours at 35°C.
IX METHODS OF DETECTION
The coliform group is quantitatively measured
by a number of procedures, such as
A Membrane filter test using a differential
medium;
B Multiple tube procedure which measures
the most probable number present on a
statistical basis; and
C Direct plate count using a differential
medium (where coliform density exceeds
10 coliforms per ml.)
The magnitude of the coliform density will
vary with the type of test procedure used.
It will also vary within a single procedure
unless identical methods are used with media
of uniform bacterial productivity. This in-
dividual variability of results makes compari-
son of tests on the same sample difficult but
does not affect the interpretation nor the
sanitary significance of the coliform data.
X THE DELAYED INCUBATION MF TEST
The delayed incubation MF test is a modifi-
cation of the MF procedure for coliform
which permits holding the bacterial on a mem-
brane several days before making the final
incubation and enumeration. Extensive field
tests indicate relatively good correlation
between the two MF procedures with the same
interpretation of sanitary significance and
water quality classification as obtained from
the completed MPN test.
Numerical variation does occur between the
MF tests and MPN test, or, to a lesser extent,
between the immediate and delayed MF tests.
Where such disagreements are of sufficient
difference to have numerical significance,
it is necessary to make detailed bacterial
29-3
-------
studies to determine which method
yields the most accurate result and the type
of bacterial flora responsible for failure of
the MF or MPN procedures.
XI PURPOSE OF DELAYED INCUBATION
MF TEST IN BASIC DATA NETWORKS
The delayed incubation MF procedure will
measure changes occurring in the coliform
density at each sample location on a weekly
basis. Increases or decreases are in turn
related to quantity of fecal pollution entering
the stream. The probability of pathogenic
organisms being present may be presumed to
increase with increasing coliform densities.
By using a medium of uniform productivity and
standardized test procedures, the differences
in results by months or years becomes the
measure of pollutional change, without con-
sideration of the absolute densities or statisti-
cal errors characteristic to each of the accepted
procedures for coliform detection and
enumeration.
This comparison of data is best accomplished
by calculating the logarithmic average or
median by months, by seasons and by each
year. Such data will permit the rapid com-
parison of increasing or decreasing pollutional
loads by months, seasons or years and the
total coliform load by use of flow rates in CFS
(cubic feet per second)for each sample location.
Since the survival, growth or death rates of
the coliform group are characteristic for
each location, extreme caution must be
exercised in comparison of data from different
locations.
XII FECAL STREPTOCOCCI
A Definition
An exact definition of the streptococci
associated with fecal pollution has not
been agreed upon by the various authorities
in the field. A working definition used by
the Water Quality Studies laboratory of
this Center is:
Fecal streptococcus are any species of
Streptococcus commonly present in signi-
ficant numbers in the fecal excreta of
humans or other warm-blooded animals. "
B Fecal Streptococcus as Pollution
Indicators
1 Advantages of fecal streptococci as
pollution indicators
a They are present in feces and
sewage.
b They are not found in pure waters or
sites out of contact with human or
animal life, so far as is currently
known.
c They are generally considered not
to multiply outside the human body
( except in rich food materials such
as milk, etc.)
d They are more resistant to elec-
trolytes than most bacteria.
e They are considered to indicate
lecal pollution when present.
2 Disadvantages of fecal streptococci as
pollution indicators
a The streptococcus density in sewage
or water is lower than the coliform
density.
b Survival time in water has not been
adequately determined in reference
to the pathogenic enteric bacteria.
29-4
-------
Significance of Bacteriologic Data
C Methods of Detection
The fecal streptococci are quantitatively
measured either by a multiple tube pro-
cedure which measures the most probable
number present on a statistical basis, or
by a membrane filter test using a differential
medium. In addition, direct plate count
methods may be employed using a
differential medium (where fecal strep-
tococcus density exceeds 10 per ml.)
useful supplemental indicator where the
coliform data may be subject to doubt or
denied as to fecal origin. The fecal
streptococcus group may have little
value in the examination of treated water
supplies but have useful application in
stream pollution investigations, evaluation
of degree of pollution in certain types of
surface water, examination of swimming
pools or similar uses.
D Current Status
The fecal streptococcus group is recognized
as a tentative test procedure in the 12th
Edition of Standard Methods, APHA 1965.
The characteristics and distribution of this
group in nature suggest it would be a most
This outline was prepared for the Training
Program by the late Harold F. Clark,
Microbiologist, and updated by Rocco
Russomanno, Microbiologist.
29-5
-------
EXAMINATION OF WATER FOR COLIFORM AND
FECAL STREPTOCOCCUS GROUPS
(Multiple Dilution Tube (MPN) Methods)
I INTRODUCTION
The subject matter of this outline is contained
in three parts, according to the following plan:
A Part 1
1 Fundamental aspects of multiple dilution
tube ("most probable numbers") tests,
both from a qualitative and a quantitative
viewpoint.
2 Laboratory bench records.
3 Useful techniques in multiple dilution
tube methods.
4 Standard supplies, equipment, and
media in multiple dilution tube tests.
B Part 2
Detailed, day-by-day, procedures in tests
for the coliform group and subgroups
within the coliform group.
C Part 3
Detailed, day-by-day, procedures in tests
for members of the fecal streptococci.
D Application of Tests to Routine Examinations
The following considerations (Table 1) apply
to the selection of the Presumptive Test,
the Confirmed Test, and the Completed
Test. Termination of testing at the
Presumptive Test level is not practiced
by FWQA laboratories and it must be
realized that the Presumptive Test alone
has limited use when water quality is to be
determined by existing standards.
TABLE 1
Type of Receiving
Water
Presumptive
Test
Confirmed Test
Completed Test
Sewage Receiving
Treatment Plant - Raw
Applicable
Applicable
Applicable
Applicable
Important where results
are to be used for control
of raw or finished water.
Application to a statis-
tically valid number of
samples from the
Confirmed Test to estab-
lish its validity in
determining the sanitary
quality.
Chlorinated
Not Done
Applicable
Bathing
Not Done
Applicable
Drinking
Not Done
Applicable
Other Information
Applicable in all
cases where Pre-
sumptive Test alone
is unreliable.
NOTE: Mention of commercial products and manufacturers does not imply endorsement by the
Federal Water Pollution Control Administration and the U.S. Department of the Interior.
W. BA. 3k. 7. 70
30-1
-------
MPN Methods
II BASIS OF MULTIPLE TUBE TESTS
A Qualitative Aspects
1 For purely qualitative aspects of testing
for indicator organisms, it is convenient
to consider the tests applied to one
sample portion, inoculated into a tube
of culture medium, and the follow-up
examinations and tests on results of the
original inoculation. Results of testing
procedures are definite: positive
(presence of the organism-group is
demonstrated) or negative (presence of
the organism-group is not demonstrated.)
2 Test procedures are based on certain
fundamental assumptions:
a First, even if only one living cell of
the test organism is present in the
sample, it will be able to grow when
introduced into the primary inoculation
medium,
b Second, growth of the test organism
in the culture medium will produce
a result which indicates presence of
the test organism, and,
c Third, extraneous organisms will
not grow, or if they do grow, they
will not limit growth of the test
organism, nor will they produce
growth effects that will be confused
with those of the bacterial group for
which the test is designed.
3 Meeting these assumptions usually
makes it necessary to conduct the tests
in a series of stages (for example, the
Presumptive, Confirmed, and Completed
Test stages, respectively, of standard
tests for the coliform group).
4 Features of a full, multi-stage test
a First stage: The culture medium
usually serves primarily as an
enrichment medium for the group
tested. A good first-stage growth
medium should support growth of all
the living cells of the group tested,
and it should include provision for
indicating the presence of the test
organism being studied. A first-
stage medium may include some
component which inhibits growth
of extraneous bacteria, but this
feature never should be included
if it also inhibits growth of any
cells of the group for which the
test is designed. The Presumptive
Test for the coliform group is a
good example. The medium
supports growth, presumably, of
all living cells of the coliform
group; the culture container has a
fermentation vial for demonstration
of gas production resulting from
lactose fermentation by coliform
bacteria, if present; and sodium
lauryl sulfate may be included in
one of the approved media for
suppression of growth of certain
noncoliform bacteria. This
additive apparently has no adverse
effect on growth of members of the
coliform group in the concentration
used. If the result of the first-stage
test is negative, the study of the
culture is terminated, and the result
is recorded as a negative test. No
further study is made of negative
tests. If the result of the first-
stage test is positive, the culture
may be subjected to further study
to verify the findings of the first
stage.
b Second stage: A transfer is made
from positive cultures of the first-
stage test to a second culture medium.
This test sta^e emphasizes provision
to reduce ^oiifusion of results due to
growth effects of extraneous bacteria,
commonly achieved by addition of
selective inhibitory agents. (The
Confirmed Test for coliforms meets
these requirements. Lactose and
fermentation vials are provided for
demonstration of coliforms in the
medium. Brilliant green dye and
bile salts are included as inhibitory
agents which tend to suppress growth
of practically all kinds of noncoliform
bacteria, but do not suppress growth
of coliform bacteria when used as
directed).
30-2
-------
MPN Methods
If result of the second-stage test is
negative, the study of the culture is
terminated, and the result is re-
corded as a negative test. A negative
test here means that the positive
results of the first-stage test were
"false positive, " due to one or more
kinds of extraneous bacteria. A
positive second-stage test is partial
vertificatioakof the positive results
obtained in the first-stage test, the
culture may be subjected to final
verification through application of
still further testing procedures. In
routine practice, most sample exami-
nations are terminated at the end of
the second stage, on the assumption
that the result would be positive if
earned to the third, final verification
stage. This practice should be
followed only if adequate testing is
done to demonstrate that the assump-
tion is valid. Some workers recom-
mend continuing at least 5% of all
sample examinations to the third
stage to demonstrate the reliability
of the second-stage results.
B Quantitative Aspects of Tests
1 These methods for determining bacterial
numbers are based on the assumption
that the bacteria can be separated from
one another (by shaking or other means)
resulting in a suspension of individual
bacterial cells, uniformly distributed
through the original sample when the
primary inoculation is made.
2 Multiple dilution tube tests for quantita-
tive determinations apply a Most Probable
Number (MPN) technique. In this pro-
cedure one or more measured portions
of each of a stipulated series of de-
creasing sample volumes is inoculated
into the first-stage culture medium.
Through decreasing the sample incre-
ments, eventually a volume is reached
where only one cell is introduced into
some tubes, and no cells are introduced
into other tubes. Each of the several
tubes of sample-inoculated first-stage
medium is tested independently,
according to the principles previously
described, in the qualitative aspects
of testing procedures.
3 The combination of positive and
negative results is used in an application
of probability mathematics to secure
a single MPN value for the sample.
4 To obtain MPN values, the following
conditions must be met:
a The testing procedure must result
in one or more tubes in which the
test organism is demonstrated to
be present; and
b The testing procedure must result
in one or more tubes in which the
test organism is not demonstrated
to be present.
5 The MPN value for a given sample is
obtained through the use of MPN Tables.
It is emphasized that the precision of
an individual MPN value is not great
when compared with most physical or
chemical determinations. The precision
of results, based on numbers of tubes
inoculated per sample volume, is shown
in Table 2.
6 Standard practice in water pollution
surveys conducted by this organization,
is to plant five tubes in each of a series
of sample increments, in sample
volumes decreasing at decimal intervals.
For example, in testing known polluted
waters, the initial sample inoculations
might consist of 5 tubes each in volumes
of 0.1, 0.01,0.001, and 0.0001 ml,
respectively This series of sample
volumes will yield determinate results
from a low of 200 to a high of 1, 600, 000
organisms per 100 ml.
30-3
-------
MPN Methods
Table 2. Approximate Confidence Limits for Bacterial Densities as
Per Cent of MPN as Determined from Various Numbers of Tubes
in Three Decimal Dilutions*
Number of tubes 50% 75% 80% 90%
in each dilution Lower Upper Lower Upper Lower Upper Lower Upper Lower Upper
33
186
18
340
15
402
10
637
6. 5
955
47
160
31
246
27
276
20
383
15
511
53
150
38
215
34
237
26
311
21
395
64
139
49
182
46
196
37
241
31
289
76
127
63
152
60
160
52
184
46
208
~The interpretation of these figures is as follows: When MPN estimates are
made on the basis of dilution tests using one tube in each of three decimal
dilutions, you will be right 50% of the time if you say that the true bacterial
density is between 33% and 186% of the MPN. If you had used 5 tubes in each
dilution you could reduce this interval to from 64% to 139% of .the MPN and still
be right 50% of the time. If a greater certainty were desired, say 95%>, you
would have to widen this interval to from 31% to 289%.
IH LABORATORY BENCH RECORDS
A Features of a Good Bench Record Sheet
1 Provides complete identification of the
sample.
2 Provides for full, day-by-day informa-
tion about all tests performed on the
sample.
3 Provides easy step-by-step record
applicable to any portion of the sample.
4 Provides for recording of the quantitative
result which will be transcribed to sub-
sequent reports.
5 Minimizes the amount of writing by the
analyst.
B There is no such thing as "standard"
bench sheet for multiple tube tests, there
are many versions of bench sheets. Some
are prescribed by administrative authority
(such as the Office of a State Sanitary
Engineer), others are devised by laboratory
or project personnel to meet specific needs.
It is not the purpose of this discussion to
recommend an "ideal" bench form, however,
the form used in this training course
manual is essentially similar to that used
in certain research laboratories of this
organization. The student enrolled in the
course for which this manual is written
should make himself thoroughly familiar
with the bench sheet and its proper use.
See Figure 1.
IV NOTES ABOUT WORKING PROCEDURES
IN THE LABORATORY
A Each bacteriological examination of water
by multiple dilution tube methods requires
a considerable amount of manipulation,
much is quite repetitious. Laboratory
workers must develop and maintain good
routine working habits, with constant
alertness to guard against lapses into
careless, slip-shod laboratory procedures
and "short cuts" which only can lead to
lowered quality of laboratory work.
3 0-4
-------
BACTERIOLOGY BENCH SHEET
Multiple Dilution Tube Tests
Project
Sample Station
Collection Data
rature
Date
Tempe
Other Observations
Time f:£C> By
/_°c PH
Bench Number of Sample
Analyst_^^— (krffosL
Analytical Record
Test started at By ///.
t
ml
sample
Coliform Test
Fecal
coli-
form
24
Fecal
Remarks
LTB
BGLB
EMB
LSTB
Gram
stain
A - D
EVA
1
to
rfx
00
24
48
24
24
48
00
CM
24
48
to
:x
/.0
1
i
1
i
1
i
0./
I
i
i
i
i
1
A0/
i
0.OS)/
1
1
I
Coliform MPN/100 ml
Confirmed
Completed-
• Ctl Coliform MPN
Fecal Streptococcus MPN/100 ml
A -D - EVA
Figure 1 SAMPLE BENCH SHEET
-------
MPN Methods
The student reader is urged to review the
form for laboratory surveys (PHS-875,
Rev. 1966) used by Public Health Service
personnel charged with responsibility for
accreditation of laboratories for examination
of water under Interstate Quarantine
regulations.
B Specific attention is brought to the following
by no means exhaustive, critical aspects of
laboratory procedures in multiple dilution
tube tests:
1 Original sample
a Follow prescribed care and handling
procedures before testing.
b Maintain absolute identification of
sample at all stages in testing.
c Vigorously shake samples {and
sample dilutions) before planting
in culture media.
2 Sample measurement into primary
culture medium
a Sample portions must be measured
accurately into the culture medium
for reliable quantitative tests to be
made. Standard Methods prescribes
that calibration errors should not
exceed + 2. 5%.
Suggested sample measuring practices
are as follows: Mohr measuring
pipets are recommended. 10 ml
samples are delivered at the top of
the culture tube, using 10 ml pipets.
1. 0 ml samples are delivered down
into the culture tube, near the sur-
face of the medium, and "touched
off" at the side of the tube when the
desired amount of sample has been
delivered. 1. 0 ml or 2. 0 ml pipets
are used for measurement of this
volume. 0. 1 ml samples are
delivered in the same manner as 1. 0
ml samples, using great care that
the sample actually gets into the
culture medium. Only 1.0 ml pipets
are used for this sample volume.
After delivery of all sample incre-
ments into the culture tubes, the
entire rack of culture tubes may be
shaken gently to carry down any of
the sample adhering to the wall of
the tube above the medium.
Workers should demonstrate by actual
tests that the pipets and the technique
in use actually delivers the rated volumes
within the prescribed limits of error.
b Volumes as small as 0.1 ml routinely
can be delivered directly from the
sample with suitable pipets. Lesser
sample volumes first should be diluted,
with subsequent delivery of suitable
volumes of diluted sample into the
culture medium. A diagrammatic
scheme for making dilutions is shown
in Figure 2.
3 Reading of culture tubes for gas
production
a On removal from the incubator,
shake culture rack gently, to
encourage release of gas which
may be supersaturated in the culture
medium.
b Gas in any quantity is a positive test.
It is necessary to work in conditions
of suitable lighting for easy recog-
nition of the extremely small amounts
of gas inside the tops of some
fermentation vials.
4 Reading of liquid culture tubes for
growth as indication of a positive test
requires good lighting. Growth is
shown by any amount of increased
turbidity or opalescence in the culture
medium, with or without deposit of
sediment at the bottom of the tube.
5 Transfer of cultures with inoculation
loops and needles
30-6
-------
MPN Methods
Dilution Ratios
Figure 2. PREPARATION OF DILUTIONS
,2
1 10
1 ml
99 ml
blank
1 ml
1 ml
0. 1ml
0. 1 ml
1 ml
Delivery volume 10 ml
For label code
See Table 2
Water
Sample
1- 10
V blank /
Tubes
Petri Dishes or Culture Tubes
Actual volume
of sample in tube
10 ml
1 ml
10 * ml 10 ^ ml 10 ^ ml
10 ^ ml 10 ^ ml
a Always sterilize inoculation loops
and needles in flame immediately
before transfer of culture, do not
lay it down or touch it to any non-
sterile object before making the
transfer.
b After sterilization, allow sufficient
time for cooling, in the air, to avoid
heat-killing bacterial cells on the
hot wire.
c Loops should be 3 mm in inside
diameter, with a capability of holding
a drop of water or culture.
For routine standard transfers
requiring transfer of 3 loopsful of
culture, many workers form three
3-mm loops on the same length of
wire.
6 As an alternative to use of standard
inoculation loops, increasing attention
is being given to use of sterilized
applicator sticks.
The applicator sticks are dry heat
sterilized (autoclave sterilization is
not acceptable because of possible
release of phenols if the wood is
steamed) and are used on a single-
service basis. Thus, for every culture
tube transferred, a new applicator
stick is used.
This use of applicator sticks is
particularly attractive in field
situations where it is inconvenient or
impossible to provide a gas burner
suitable for sterilization of the
inoculation loop. In addition, use of
applicator sticks is favored in
laboratories where room temperatures
are significantly elevated by use of
gas burners.
It is anticipated that use of wooden
applicator sticks in culture transfers
will receive formal sanction in the next
(13th) edition of Standard Methods.
30-7
-------
MPN Methods
7 Streaking cultures on agar surfaces
a All streak-inoculations should be
made without breaking the surface
of the agar. Learn to use a light
touch with the needle, however,
many inoculation needles are so
sharp that they are virtually useless
in this respect. When the needle is
platinum or platinum-iridium wire,
it sometimes is beneficial to fuse
the working tip into a small sphere.
This can be done by momentary
insertion of a well-insulated (against
electricity) wire into a carbon arc,
or some other extremely hot environ-
ment. The sphere should not be more
than twice the diameter of the wire
from which it is formed, otherwise
it will be entirely too heat-retentive
to be useful.
When the needle is nichrome
resistance wire, it cannot be heat-
fused, the writer prefers to bend
the terminal 1/16 - 1/8" of the wire
at a slight angle to the overall axis
of the needle. The side of the
terminal bent portion of the needle
then is used for inoculation of agar
surfaces.
b When streaking for colony isolation,
avoid using too much inoculum. The
streaking pattern is somewhat
variable according to individual
preference. The procedure favored
by the writer is shown in the
accompanying figures. Note
particularly that when going from
any one stage of the streaking to the
next, the inoculation needle is heat-
sterilized.
8 Preparation of cultures for Gram
stain
a The Gram stain always should be
made from a culture grown on a
nutrient agar surface (nutrient agar
slants are used here) or from nutrient
broth.
b The culture should be young, and
should be actively growing. Many
workers doubt the validity of the
Gram stain made on a culture more
than 24 hours old.
c Prepare a thin smear for the staining
procedure Most beginning workers
tend to use too much bacterial sus-
pension in preparing the dried smear
for staining. The amount of bacteria
should be so small that the dried film
is barely visible to the naked eye.
V EQUIPMENT AND SUPPLIES
Consolidated lists of equipment, supplies,
and culture media required for all multiple
dilution tube tests described in this outline
are shown in Table 3, Quantitative infor-
mation is not presented, this is variable-
according to the extent of the testing pro-
cedure, the number of dilutions used, and
the number of replicate tubes per dilution.
It is noted that requirements for alternate
procedures are fully listed and choices are
made in accordance to laboratory preference.
30-8
-------
MPN Methods
a Flame-sterilize an inoculation needle and air-cool.
b Dip the tip of the inoculation needle into the bac-
terial culture being studied.
c Streak the inoculation needle tip lightly back and
forth over half the agar surface, as in (1), avoid-
ing scratching or breaking the agar surface.
d Flame-sterilize the inoculation needle and air-cool.
Turn the Petri dish one-quarter-turn and streak the
inoculation needle tip lightly back and forth over one-
half the agar surface, working from area (1) into one-
half the unstreaked area of the agar.
Flame-sterilize the inoculation needle and air-cool.
Turn the Petri dish one-quarter-turn and streak the
inoculation needle tip lightly back and forth over one-
half the agar surface, working from area (2) into
area (3), the remaining unstreaked area.
Flame-sterilize the inoculation needle and set it aside.
Close the culture container and incubate as prescribed.
Figure 3. A SUGGESTED PROCEDURE FOR COLONY ISOLATION BY A
STREAK-PLATE TECHNIQUE
3 0-9
-------
MPN Methods
TABLE 3. APPARATUS AND SUPPLIES FOR STANDARD AND
NONSTANDARD FERMENTATION TUBE TESTS
30-10
Description of Item
Total CoUform Group
Fecal
^oliforms
Presumptive
T est
Confirmed
Test
Completed
Test
(BA LB)
(EC broth)
Lauryl tryptose broth or Lactose
broth 20 ml amounts of 1 5 X
concentration medium, in 25 X ISO mm
culture tubes with inverted fermen-
tation vialsr metal caps
X
Lauryl tryptose broth or f^ctose
broth 10 ml amounts of single
strength medium in 20 Y 150 mm
culture tubes with inverted fermen-
tation vials metal caps
X
X
Brilliant green lactose bile broth 2%
in 10 ml amounts single strength,
in 20 X 150 mm culture tubes with
inverted fermentation vials, metal
caps
X
Eosin methylene blue agar, poured
in 100 X 15 mm Petri dishes
X
X
Endo Agar, poured in 100 X 15 mm
dishes
X
Boric acid lactose broih 10 ml
amounts of single strength medium
in fermentation tubes
X
EC Broth 10 ml amounts of single
strength medium in fermentation
lubes, metal caps
X
Formate ricinoleate broth
(provisional)
X
Culture tube racks, 10X5 openings,
each opening to accept 25 mm dia-
mctcr tubes
X
X
X
X
\
Pipettes 10 ml, Mohr type, sterile,
in metai cane
X
Pipettes, 2 ml (optional), Morh t>pe,
sterile, in metal cans
X
Pipettes, 1 ml Mohr type, sterile
in metal cans
X
Standard buffered dilution Mater,
sterile, 99-ml amounts in screw-
cappcd bottles
X
Gas burner Bunscn type
X
X
X
\
Inoculation loop, loop 3mm din-
meter, of nichrome or platinum -
iridium wire, 26 B it 5 gauge, ui
suitable holder (t r sterile ar licator
stick)
X
X
X
X
Inoculation needle, nichrome, or
platlnum-lridlum wire 26 B & S
gauge, in suitable holder
X
Incubator, adjusted to 35 + 0 50 C
X
X
X
Waterbath incubator, adjusted to
43 + 0 50C
X
Waterbath incubator, adjusted to
44 0 - 45 0o C
X
Glass microscopic slides l" X3 '
X
Slide racks (optional)
X
Gram-stain solutions, complete set
X
Compound microscope oil immer-
sion lens, Abbe' condenser
X
Basket for discarded cultures
X
X
X
X
X
Container for discarded pipettes
X
-------
Part 2
DETAILED TESTING PROCEDURES FOR MEMBERS OF THE
COLIFORM GROUP BY MULTIPLE DILUTION TUBE METHODS
I SCOPE
A Tests Described
1 Presumptive Test
2 Confirmed Test
3 Completed Test
4 Fecal Coliform Test
B Form of Presentation
The Presumptive, Confirmed, and
Completed Tests are presented as total,
independent procedures. It is recognized
that this form of presentation is somewhat
repetitious, inasmuch as the Presumptive
Test is but preliminary to the Confirmed
Test, and both the Presumptive Test and
the Confirmed Test are preliminary to the
Completed Test for total coliforms.
In using these procedures, the worker
must know at the outset what is to be the
stage at which the test is to be ended, and
the details of the procedures throughout.
In order to prevent the possibility of
discarding gas-positive tubes before
proper transfer procedures have been
followed.
Thus, if the worker knows that the test will
be ended at the Confirmed Test, he will
turn at once to Section HI, TESTING TO
THE CONFIRMED TEST STAGE, and will
ignore Sections II and IV.
The Fecal Coliform Test is described
separately, in Section V, as ai} optional
adjunct to the Confirmed Test and to the
Completed Test.
II TESTING TO PRESUMPTIVE TEST
STAGE
A First-Day Procedures
1 Prepare a laboratory data sheet for
the sample. Record the following
information: assigned laboratory
number, source of sample, date and
time of collection, temperature of the
source, name of sample collector,
date and time of receipt of sample in
the laboratory. Also show the date
and time of starting tests in the
laboratory, name(s) of worker(s) per-
forming the laboratory tests, and the
sample volumes planted.
2 Label the tubes of lauryl tryptose broth
required for the initial planting of the
sample (Table 4). The label should
bear three identifying marks. The
upper number is the identification of
the workers) performing the test
(applicable to personnel in SEC training
courses), the number immediately
below is the assigned laboratory num-
ber, corresponding with the laboratory
record sheet. The lower number is the
code to designate the sample volume
and which tube of a replicate series is
indicated.
NOTE: If 10-ml samples are being planted,
be sure to use tubes containing the correct
concentrations of culture medium. See
Table 5 to adjust for the dilution factor.
3 Place the labeled culture tubes in an
orderly arrangement in a culture tube
rack, with the tubes intended for the
largest sample volumes in the front
row, and those intended for smaller
volumes in the succeeding rows.
W.BA. 3k. 7. 70
30-11
-------
MPN Methods
Table 4 SUGGESTED LABELING SCHEME FOR ORIGINAL CULTURES AND
SUBCULTURES IN MULTIPLE DILUTION TUBE TESTS
Tube
1
Tube
2
Tube
3
Tube
4
Tube
5
Sample volume
represented
Bench number
Volume & tube
312
A
312
B
312
C
312
D
312
E
Tubes with 10 ml
of sample
Bench number
Volume & tube
312
a
312
b
312
c
312
d
312
e
Tubes with 1 ml
of sample
Bench number
Volume & tube
312
a
312
_b
312
c
312
d
312
e
Tubes with 0. 1 ml
of sample
Bench number
Volume & tube
312
la
312
lb
312
lc
312
Id
312
le
Tubes with 0.01 ml
of sample
Bench number
Volume & tube
312
2a
312
2b
312
2c
312
2d
312
2e
Tubes with 0.001 ml
of sample
Typical Example
Lab Worker
ifIdentification
-Bench Number
"Sample Volume
Tube of Culture Medium
The labeling of cultures can be reduced by labeling only the first tube of
each series of identical sample volumes in the initial planting of the sample.
All subcultures from initial plantings should be labeled completely.
TABLE 5
VOLUME-CONCENTRATION RELATIONSHIPS OF PRIMARY
INOCULUM MEDIUM FOR INITIAL SAMPLE VOLUMES
Amt. of Medium Volume of Medium Dehydrated Lactose
Inoculum in Tube and Inoculum Broth Required
ml. ml. ml. Grams/Liter
1 ml or less 10 ml. 10 ml. 13 g.
10 10 20 26. 0 g.
10 20 30 19.5 g.
Dehydrated Lauryl
Inoculum
ml.
Amt. of Medium
in Tube
ml.
Volume of Medium
and Inoculum
ml.
Tryptose Lactose
Broth Required
Grams / Liter
1 ml or less
10 ml.
10 ml.
35.6 g.
10
10
20
71.2 g.
10
20
30
53.4 g.
10
30
40
47.3 g.
30-12
-------
MPN Methods
4 Shake the sample vigorously, approxi-
mately 25 times, in an up-and-down
motion.
5 Measure the predetermined sample
volumes into the labeled tubes of
lauryl tryptose broth, using care to
avoid introduction of any bacteria into
the culture medium except those in the
sample.
a Use a 10 ml pipet for 10 ml sample
portions, and 1 ml pipets for portions
of 1 ml or less. Handle sterile
pipets only near the mouthpiece, and
protect the delivery end from
external contamination.
b When using the pipet to withdraw
sample portions, do not dip the
pipet more than 1/2 inch into the
sample; otherwise sample running
down the outside of the pipet will
make measurements inaccurate.
6 After measuring all portions of the
sample into their respective tubes of
medium, gently shake the rack of
inoculated tubes to insure good mixing
of sample with the culture medium.
Avoid vigorous shaking, as air bubbles
may be shaken into the fermentation
vials and thereby invalidate the test.
7 Place the rack of inoculated tubes in the
incubator at 35° + 0.5°C for 24 +
2 hours
B 24-hour Procedures
1 Remove the rack of lauryl tryptose
broth cultures from the incubator, and
shake gently. If gas is about to appear
in the fermentation vials, the shaking
will speed the process.
2 Examine each tube carefully Record,
in the column "24" under LST on the
laboratory data sheet, each tube showing
gas in the fermentation vial as a positive
(+) test and each tube not showing gas
as a negative (-) test GAS IN ANY
QUANTITY IS A POSITIVE TEST.
3 Discard all gas-positive tubes of lauryl
tryptose broth, and return all the gas-
negative tubes to the 35°C incubator
for an additional 24+2 hours.
C 48-hour Procedures
1 Remove the rack of culture tubes from
the incubator, read and record gas
production for each tube.
2 Be sure to record all results under the
48-hour LTB column on the data sheet
Discard all tubes. The Presumptive
Test is concluded at this point, and
Presumptive coliforms per 100 ml can
be computed according to the methods
described elsewhere in this manual.
HI TESTING TO CONFIRMED TEST STAGE
Note that the description starts with the
sample inoculation and includes the
Presumptive Test stage. The Confirmed
Test preferred in FWQA Laboratories is
accomplished by means of the brilliant
green lactose bile broth (BGLB) and the
acceptable alternate tests are mentioned
in HI F. In addition, the Fecal Coliform
Test is included as an optional adjunct to
the procedure.
A First-Day Procedures
1 Prepare a laboratory data sheet for the
sample. Record the following infor-
mation- assigned laboratory number,
source of sample, date and time of
collection, temperature of the source,
name of sample collector, date and
time of receipt of sample in the
laboratory. Also show the date and
time of starting tests in the laboratory,
name(s) of worker(s) performing the
laboratory tests, and the sample
volumes planted.
Label the tubes of lauryl tryptose broth
required for the initial planting of the
sample. The label should bear three
identifying marks. The upper number
is the identification of the worker(s)
30-13
-------
MPN Methods
performing the test (applicable to
personnel in training courses), the
number Immediately below is the
assigned laboratory number, corres-
ponding with the laboratory record
sheet. The lower number is the code
to designate the sample volume and
which tube of a replicate series is
indicated.
NOTE: If 10-ml samples are being
planted, it is necessary to use tubes
containing the correct concentration
of culture medium. This has pre-
viously been noted in II A-2.
3 Place the labeled culture tubes in an
orderly arrangement in a culture tube
rack, with the tubes intended for the
largest sample volumes in the front
row, and those intended for smaller
volumes in the succeeding rows.
4 Shake the sample vigorously, approxi-
mately 25 times, in an up-and-down
motion.
5 Measure the predetermined sample
volumes into the labeled tubes of lauryl
tryptose broth, using care to avoid
introduction of any bacteria into the
culture medium except those in the
sample.
a Use a 10-ml pipet for 10 ml sample
portions, and 1-ml pipets for portions
of 1 ml or less Handle sterile pipets
only near the mouthpiece, and protect
the delivery end from external con-
tamination.
b When using the pipet to withdraw
sample portions, do not dip the
pipet more than 1/2 inch into the
sample, otherwise sample running
down the outside of the pipet will
make measurements inaccurate.
c When delivering the sample into the
culture medium, deliver sample
portions of 1 ml or less down into
the culture tube near the surface of
the medium. Do not deliver small
sample volumes at the top of the tube
and allow them to run down inside
the tube; too much of the sample
will fail to reach the culture medium.
d Prepare preliminary dilutions of
samples for portions of 0. 01 ml or
less before delivery into the culture
medium. See Table 1 for preparation
of dilutions. NOTE: Always deliver
diluted sample portions into the
culture medium as soon as possible
after preparation. The interval
between preparation of dilution and
introduction of sample into the
medium never should be as much
as 30 minutes.
6 After measuring all portions of the
sample into their respective tubes of
medium, gently shake the rack of
inoculated tubes to insure good mixing
of sample with the culture medium.
Avoid vigorous shaking, as air bubbles
may be shaken into the fermentation
vials and thereby invalidate the test
7 Place the rack of inoculated tubes in
the incubator at 35° + 0. 5°C for 24 +
2 hours.
B 24-hour Procedures
1 Remove the rack of lauryl tryptose
broth cultures from the incubator, and
shake gently If gas is about to appear
in the fermentation vials, the shaking
will speed the process.
2 Examine each tube carefully. Record,
in the column "24" under LST on the
laboratory data sheet, each tube showing
gas in the fermentation vial as a
positive (+) test and each tube not
showing gas as a negative (-) test
GAS IN ANY QUANTITY IS A POSITIVE
TEST.
3 Retain all gas-positive tubes of lauryl
tryptose broth culture in their place
in the rack, and proceed-
4 Select the gas-positive tubes of lauryl
tryptose broth culture for Confirmed
Test procedures. Confirmed Test
30-14
-------
MPN Methods
procedures may not be required for all
gas-positive cultures. If, after 24-hours
of incubation, all five replicate cultures
are gas-positive for two or more con-
secutive sample volumes, then select
the set of five cultures representing
the smallest volume of sample in which
all tubes were gas-positive. Apply
Confirmed Test procedures to all these
cultures and to any other gas-positive
cultures representing smaller volumes
of sample, in which some tubes were
gas-positive and some were gas-negative.
5 Label one tube of brilliant green lactose
bile borth (BGLB) to correspond with
each tube of lauryl tryptose broth
selected for Confirmed Test procedures.
6 Gently shake the rack of Presumptive
Test cultures. With a flame-sterilized
inoculation loop transfer one loopful of
culture from each gas-positive tube to
the corresponding tube of BGLB. Place
each newly inoculated culture into BGLB
in the position of the original gas-positive
tube.
7 After making the transfers, the rack
should contain some 24-hour gas-
negative tubes of lauryl tryptose broth
and the newly inoculated BGLB.
8 If the Fecal Coliform Test is included
in the testing procedures, consult
Section V of this part of the outline of
testing procedures.
9 Incubate the 24-hour gas-negative BGLB
tubes and any newly-inoculated tubes of
BGLB 24 + 2 hours at 350 + 0. 5°C.
10 Discard all tubes of LTB and all 24-hour
gas-positive BGLB cultures.
C 48-hour Procedures
1 Remove the rack of culture tubes from
the incubator, read and record gas
production for each tube.
2 Some tubes will be lauryl tryptose broth
and some will be brilliant green lactose
bile broth (BGLB). Be sure to record
results from LTB under the 48-hour
LTB column and the BGLB results under
the 24-hour column of the data sheet.
3 Label tubes of BGLB to-correspond with
all (if any) 48-hour gas-positive cultures
in lauryl tryptose broth. Transfer one
loopful of culture from each gas-positive
LTB culture to the correspondingly-
labeled tube of BGLB. NOTE- All
tubes of LTB culture which were
negative at 24 hours and became
positive at 48 hours are to be transferred
The option described above for 24-hour
cultures does not apply at 48 hours.
4 If the Fecal Coliform Test is included
in the testing procedure, consult
Section V of the part of the outline
of testing procedures.
5 Incubate the 24-hour gas-negative
BGLB tubes and any newly-inoculated
tubes of BGLB 24+2 hours at 35© +
0. 5° C.
6 Discard all tubes of LTB and all 24-hour
gas-positive BGLB cultures.
D 72-hour Procedures
1 If any cultures remain to be examined,
all will be BGLB. Some may be 24
hours old and some may be 48 hours
old. Remove such cultures from the
incubator, examine each tube for gas
production, and record results on the
data sheet.
2 Be sure to record the results of 24-hour
BGLB cultures in the "24" column under
BGLB and the 48-hour results under the
"48" column of the data sheet.
3 Return any 24-hour gas-negative cultures
for incubation 24 + 2 hours at 35 +
0. 5° C.
4 Discard all gas-positive BGLB cultures
and all 48-hour gas-negative cultures
from BGLB.
5 It is possible that all cultural work and
results for the Confirmed Test have
30-15
-------
MPN Methods
been finished at this point. If so, codify
results and determine Confirmed Test
coliforms per 100 ml as described in
the outline on use of MPN Tables.
E 96-hour Procedures
At most only a few 48-hour cultures in
BGLB may be present. Read and record
gas production of such cultures in the "48"
column under BGLB on the data sheet.
Codify results and determine Confirmed
Test coliforms per 100 ml.
F Streak-plate methods for the Confirmed
Test, using eosin methylene blue agar or
Endo agar plates, are accepted procedures
in Standard Methods. The worker who
prefers to use one of these media in
preference to BGLB (also approved in
Standard Methods) is advised to refer to
the current edition of "Standard Methods-
for the Examination of Water and Waste-
water. "
IV TESTING TO COMPLETED TEST STAGE
(Note that this description starts with the
sample inoculation and proceeds through the
Presumptive and the Confirmed Test stages.
In addition, the Fecal Coliform Test is
referred to as an optional adjunct to the
procedure.)
A First-Day Procedures
1 Prepare a laboratory data sheet for the
sample. Record the following information:
assigned laboratory number, source of
sample, date and time of collection,
temperature of the source, name of
sample collector, date and time of
receipt of sample in the laboratory.
Also show the date and time of starting
tests in the laboratory, name(s) of
worker(s) performing the laboratory
tests, and the sample volumes planted.
2 Label the tubes of lauryl tryptose broth
required for the initial planting of the
sample. The label should bear three
identifying marks. The upper number
is the identification of the worker(s)
performing the test (applicable to
personnel in SEC training courses),
the number immediately below is the-
assigned laboratory number, corres-
ponding with the laboratory record
sheet. The lower number is the code
to designate the sample volume and
which tube of a replicate series is
indicated. Consult Table 2, this
chapter, for guidance on labeling for
laboratory data number and identification
of individual tubes.
NOTE: If 10-ml samples are being
plated, it is necessary to use tubes
containing the correct concentration
of culture medium. This has previously
been noted in II A 2.
3 Place the labeled culture tubes in an
orderly arrangement in a culture tube
rack, with the tubes intended for the
largest sample volumes in the front
row, and those intended for smaller
volumes in the succeeding rows.
4 Shake the sample vigorously, approxi-
mately 25 times, in an up-and-down
motion.
5 Measure the predetermined sample
volumes into the labeled tubes of lauryl
tryptose broth, using care to avoid
introduction of any bacteria into the
culture medium except those in the
sample.
a Use a 10-ml pipet for 10 ml sample
portions, and 1-mlpipets for portions
of 1 ml or less. Handle sterile
pipets only near the mouthpiece,
and protect the delivery end from
external contamination.
b When using the pipet to withdraw
sample portions, do not dip the
pipet more than 1/2 inch into the
sample, otherwise sample running
down the outside of the pipet will
make measurements inaccurate.
c When delivering the sample into the
culture medium, deliver sample
portions of 1 ml or less down into
30-16
-------
MPN Methods
the culture tube near the surface of
the medium. Do not deliver small
sample volumes at the top of the
tube and allow them to run down
inside the tube; too much of the
sample will fail to reach the culture
medium.
d Prepare preliminary dilutions of
samples for portions of 0. 01 ml or
less before delivery into the culture
medium. See Table 1 for preparation
of dilutions. NOTE: Always deliver
diluted sample portions into the
culture medium as soon as possible
after preparation. The interval
between preparation of dilution and
introduction of sample into the
medium never should be as much as
30 minutes.
6 After measuring all portions of the
sample into their respective tubes of
medium, gently shake the rack of
inoculated tubes to insure good mixing
of sample with the culture medium.
Avoid vigorous shaking, as air bubbles
may be shaken into the fermentation
vials and thereby invalidate the test.
7 Place the rack of inoculated tubes in
the incubator at 35° + 0. 5°C for 24 +
2 hours.
B 24-hour Procedures
1 Remove the rack of lauryl tryptose broth
cultures from the incubator, and shake
gently. If gas is about to appear in the
fermentation vials, the shaking will
speed the process.
2 Examine each tube carefully. Record,
in the column "24" under LST on the
laboratory data sheet, each tube showing
gas in the fermentation vial as a positive
(+) test and each tube not showing gas
as a negative (-) test. GAS IN ANY
QUANTITY IS A POSITIVE TEST.
3 Retain all gas-positive tubes of lauryl
tryptose broth culture in their place in
the rack, and proceed.
4 Select the gas-positive tubes of lauryl
tryptose broth culture for the Confirmed
Test procedures. Confirmed Test
procedures may not be required for
all gas-positive cultures. If, after
24-hours of incubation, all five
replicate cultures are gas-positive for
two or more consecutive sample
volumes, then select the set of five
cultures representing the smallest
volume of sample in which all tubes
were gas-positive. Apply Confirmed
Test procedures to all these cultures
and to any other gas-positive cultures
representing smaller volumes of
sample, in which some tubes were
gas-positive and some were gas-
negative .
5 Label one tube of brilliant green lactose
bile broth (BGLB) to correspond with
each tube of lauryl tryptose broth
selected for Confirmed Test procedures.
6 Gently shake the rack of Presumptive
Test cultures. With a flame-sterilized
inoculation loop transfer one loopful of
culture from each gas-positive tube to
the corresponding tube of BGLB. Place
each newly inoculated culture into
BGLB in the position of the original
gas-positive tube.
7 If the Fecal Coliform Test is included
in the testing procedure, consult
Section V of this outline for details of
the testing procedure
8 After making the transfer, the rack
should contain some 24-hour gas-
negative tubes of lauryl tryptose borth
and the newly inoculated BGLB.
Incubate the rack of cultures at 35° C
+ 0. 5° C for 24 + 2 hours.
C 48-hour Procedures
1 Remove the rack of culture tubes from
the incubator, read and record gas
production for each tube.
2 Some tubes will be lauryl tryptose broth
and some will be brilliant green lactose
30-17
-------
MPN Methods
bile broth (BGLB). Be sure to record
results from LTB under the 48-hour
LTB column and the BGLB results
under the 24-hour column of the data
sheet.
3 Label tubes of BGLB to correspond with
all (if any) 48-hour gas-positive cultures
in lauryl tryptose broth. Transfer one
loopful of culture from each gas-positive
LTB culture to the correspondingly-
labeled tube of BGLB NOTE: All tubes
of LTB culture which were negative at
24 hours and became positive at 48 hours
are to be transferred The Option
described above for 24-hour LTB
cultures does not apply at 48 hours.
4 Incubate the 24-hour gas-negative BGLB
tubes and any newly-inoculated tubes of
BGLB 24 + 2 hours at 35Q + 0. 50C.
Retain all 24-hour gas-positive cultures
in BGLB for further test procedures.
5 Label a Petri dish preparation of eosin
methylene blue agar (EMB agar) to
correspond with each gas-positive
culture in BGLB.
6 Prepare a streak plate for colony
isolation from each gas-positive culture
in BGLB on the correspondingly-labeled
EMB agar plate.
Incubate the EMB agar plates 24 + 2
hours at 35° + 0. 5° C.
D 72-hour Procedures
1 Remove the cultures from the incubator.
Some may be on BGLB, several EMB
agar plates also can be expected.
2 Examine and record gas production
results for any cultures m BGLB.
3 Retain any gas-positive BGLB cultures
and prepare streak plate inoculations
for colony isolation in EMB agar.
Incubate the EMB agar plates 24 +
2 hours at 35 + 0. 5° C Discard "the
gas-positive BGLB cultures after
transfer.
4 Reincubate any gas-negative BGLB
cultures 24 + 2 hours at 35° + 0. 5° C.
5 Discard all 48-hour gas-negative BGLB
cultures.
6 Examine the EMB agar plates for the
type of colonies developed thereon.
Well-isolated colonies having a dark
center (when viewed from the lower
side, held toward a light) are termed
"nucleated or fisheye" colonies, and
are regarded as "typical" coliform
colonies. A surface sheen may or may
not be present on "typical" colonies.
Colonies which are pink or opaque but
are not nucleated are regarded as
"atypical colonies. " Other colony
types are considered "noncoliform. "
Read and record results as + for
"typical" (nucleated) colonies + for
"atypical" (non-nucleated pink or
opaque colonies), and - for other types
of colonies which might develop.
7 With plates bearing "typical" colonies,
select at least one well-isolated colony
and transfer it to a correspondingly-
labeled tube of lactose broth and to an
agar slant. As a second choice, select
at least two "atypical" colonies (if
typical colonies are not present) and
transfer them to labeled tubes of
lactose broth and to agar slants. As a
third choice, in the absence of typical
or atypical coliform-like colonies,
select at least two well-isolated
colonies representative of those
appearing on the EMB plate, and trans-
fer them to lactose broth and to agar
slants.
8 Incubate all cultures transfered from
EMB agar plates 24+2 hours at 35 +
0. 5° C.
E 96-hour Procedures
1 Subcultures from the samples being
studied may include: 48-hour tubes
of BGLB, EMB agar plates, lactose
broth tubes, and agar slant cultures.
30-18
-------
MPN Methods
'2 If any 48-hour tubes of BGLB are
present, read and record gas production
in the "48" column under BGLB. From
any gas-positive BGLB cultures pre-
pare streak plate inoculations for colony
isolation on EMB agar. Discard all
tubes of BGLB, and incubate EMB agar
plates 24 + 2 hours at 35 + 0. 5°C.
3 If any EMB plates are present, examine
and record results in the "EMB" column
of the data sheet. Make transfers to
agar slants and to lactose broth from
all EMB agar plate cultures. In
decreasing order of preference, transfer
at least one typical colony, or at least
two atypical colonies, or at least two
colonies representative of those on the
plate.
4 Examine and record results from the
lactose broth cultures.
5 Prepare a Gram-stained smear from
each of the agar slant cultures, as
follows:
NOTE: Always prepare Gram stain
from an actively growing culture,
preferably about 18 hours old, and
never more than 24 hours old. Failure
to observe this precaution often results
in irregular staining reactions.
a Thoroughly clean a glass slide to
free it of any trace of oily film.
b Place one drop of distilled water on
the slide.
c Use the inoculation needle to suspend
a tiny amount of growth from the
nutrient agar slant culture in the
drop of water.
d Mix the thin suspension of cells with
the tip of the inoculation needle, and
allow the water to evaporate.
e "Fix" the smear by gently warming
the slide over a flame.
f Stain the smear by flooding it for 1
minute with crystal violet solution.
g Flush the excess crystal violet
solution off in gently running water,
and gently blot dry with filter
paper or with other clean absorbent
paper.
h Flood the smear with Lugol's
iodine for 1 minute.
i Wash the slide in gently running
water and blot dry with filter paper.
j Decolorize the smear with 95%
alcohol solution with gentle
agitation for 10-30 seconds,
depending upon extent of removal
of crystal violet dye, then blot dry.
k Counterstain for 10 seconds with
safranin solution, then wash in
running water and blot dry.
1 Examine the slide under the
microscope, using the oil
immersion lens. Goliform
bacteria are Gram-negative,
nonspore-forming, rod-shaped
cells, occurring singly, in pairs,
or rarely in short chains.
m If typical coliform staining reaction
and morphology are observed,
record + in the appropriate space
under the "Gram Stain" column of
the data sheet. If typical morphology
and staining reaction are not
observed, then mark it + or -, and
make suitable comment in the
"remarks" column at the right-hand
side of the data sheet.
n If spore-forming bacteria are
observed, it will be necessary to
repurify the culture from which
the observations were made.
Consult the instructor, or refer
to Standard Methods, for procedures.
At this point, it is possible that all
cultural work for the Completed Test
has been finished. If so, codify results
and determine Completed Test coliforms
per 100 ml.
30-19
-------
MPN Methods
F 120-hour Procedures and following:
1 Any procedures to be undertaken from
this point are "straggler" cultures on
media already described, and requiring
step-by-step methodology already given
in detail. Such cultures may be on:
EMB plates, agar slants, or lactose
broth. The same time-and-temperature
of incubation required for earlier studies
applies to the "stragglers" as do the
observations, staining reactions, and
interpretation of results. On con-
clusion of all cultural procedures,
codify results and determine Completed
Test coliforms per 100 ml.
V FECAL COLIFORM TEST
A General Information
1 The procedure described is an elevated
temperature test for fecal coliform
bacteria.
2 Equipment required for the tests are
those required for the Presumptive
Test of Standard Methods, a water-bath
incubator, and the appropriate culture
media.
B Fecal Coliform Test with EC Broth
1 Sample: The test is applied to gas-
positive tubes from the Standard
Methods Presumptive Test (lauryl
tryptose broth), in parallel with
Confirmed Test procedures.
2 24-hour Operations. Initial procedures
are the planting procedures described
for the Standard Methods Presumptive
Coliform test.
a After reading and recording gas-
production on lauryl tryptose broth,
temporarily retain all gas-positive
tubes.
b Label a tube of EC broth to corre-
spond with each gas-positive tube
of lauryl tryptose broth. The option
regarding transfer of only a limited
number of tubes to the Confirmed
Test (see n, B, 5) sometimes can
be applied here. However, the
worker is urged to avoid exercise
of this option until he has assured
the applicability of the option by
preliminary tests on the sample
source.
c Transfer one drop of culture from
each gas-positive culture in lauryl
tryptose broth to the correspondingly
labeled tube of EC broth
d Incubate EC broth tubes 24 + 2 hours
at 44. 0 - 45 0° C, in a waterbath
with water depth sufficient to come
up at least as high as the top of the
culture medium in the tubes. Place
in waterbath as soon as possible
after inoculation and always within
30 minutes after inoculation.
3 4 8-hour operations
a Remove the rack of EC cultures
from the waterbath, shake gently,
and record gas production for each
tube. Gas in any quantity is a
positive test.
b As soon as results are recorded,
discard all tubes (This is a 24-
hour test for EC broth inoculations
and not a 48-hour test.)
c Transfer any additional 48-hour
gas-positive tubes of lauryl tryptose
broth to correspondingly labeled
tubes of EC broth Incubate 24 +
2 hours at 44 0 - 45.0OC.
4 72-hour operations
a Read and record gas production for
each tube. Discard all cultures.
b Codify results and determine fecal
coliform count per 100 ml of sample.
30-20
-------
MPN Methods
TESTS FOR COUFORM GROUP
SAMPtE
a.
§
in
LACTOSE OR LAURYL TRYPTOSE BROTH
FERMENTATION TUBES (SERIAL DILUTION)
GAS POSITIVE
: (74 HR + 2 HR }
CAS NEGATIVE
I
LACTOSE « LAURYL WYfTOSf
MOTH ARE INTERCHANGEABLE MECHA
AMD ARE 9KUBATED AT 35 DEG C*
OS DEG C.
GAS POSITIVES TUBES (ANY AMOUNT
OF GAS) CONSTITUTE A POSITIVE
PRESUMPTIVE TEST
TOTAL INCUBATION TIME FOR LACTOSE
OR LTB IS 48 HRS ± 3 HRS
GAS TOSfTIVE
GAS NEGATIVE
COUFOKM GROUP ABSENT
t <"
I
CONFKMATORY BROTH
BRILLIANT GREEN LACTOSE BILE
•J EMS PtATES
OR
ENDO AGAR
PLATES
ALTERNATE
CONFIRMED
GAS POSITIVE
GAS NEGATIVE
COUFOKM GROUP
NOT CO NF KM ED
COUFORM GROUP
CONFIRMS)
EMB PLATES
LACTOSE BROTH TUBE
NUTRIENT AGAR SLANT
\
a
£
3E
O
u
GRAM + AND
RODS AND/OR
SPO REFORMERS
FOCMATE
RKIMOUATE
BROTH
GRAM NEGATIVE
RODS
MO SPORES
GAS POSITIVE
COLFORM GROUP PRESENT
COMPLETED TEST
GAS POSITIVE
GAS NEGATIVE
I
COUFOKM GROUP ABSENT
TRANSFER TO EMB PLATE
AND REPEAT PROCESS
INCUBATE BGLB TUBES FOR 43 HRS
± 3 HRS AT 35 DEG C± OJ DEG C
INCUBATE EMB OR ENOOAGAR
PLATES FOR 24 HRS ± 2 HRS AT
35 DEG C± 0-5 DEG C
GAS NEGATIVE
COUFOKM GROUP ABSENT
21
-------
Part 3
LABORATORY METHODS FOR FECAL STREPTOCOCCUS
(Day-By-Day Procedures)
I GENERAL INFORMATION
A The same sampling and holding procedures
apply as for the coliform test.
B The number of fecal streptococci in water
generally is lower than the number of
coliform bacteria. It is good practice
in multiple dilution tube tests to start the
sample planting series with one sample
increment larger than for the coliform
test. For example: If a sample planting
series of 1.0, 0.1, 0.01, and 0.001 ml
is planned for the coliform test, it is
suggested that a series of 10, 1.0, 0. 1,
and 0.01 ml be planted for the fecal
streptococcus test.
C Equipment required for the test is the same
as required for the Standard Methods
Presumptive and Confirmed Tests, except
for the differences in culture media.
E STANDARD METHODS (Tentative)
PROCEDURES
A First-Day Operations
1 Prepare the sample data sheet and
labeled tubes of azide dextrose broth
in the same manner as for the
Presumptive Test. NOTE: If 10-ml
samples are included in the series, be
sure to use a special concentration
(ordinarily double-strength) of azide
dextrose broth for these sample
portions.
2 Shake the sample vigorously, approxi-
mately 25 times, in an up-and-down
motion.
3 Measure the predetermined sample
volumes into the labeled tubes of azide
dextrose broth, using the sample
measurement and delivery techniques
used for the Presumptive Test.
4 Shake the rack of tubes of inoculated
culture media, to insure good mixing
of sample with medium.
5 Place the rack of inoculated tubes in
the incubator at 35° + 0. 5° C for 24 +
2 hours.
B 2 4-hour Operations
1 Remove the rack of tubes from the
incubator. Read and record the results
from each tube. Growth is a positive
test with this test. Evidence of growth
consists either of turbidity of the
medium, a "button" of sediment at the
bottom of the culture tube, or both.
2 Label a tube of ethyl violet azide broth
to correspond with each positive culture
of azide dextrose broth. It may be
permissible to use the same confirmatory
option as described for the coliform
Confirmed Test, in this outline.
3 Shake the rack of cultures gently, to
resuspend any living cells which have
settled out to the bottom of the culture
tubes.
4 Transfer three loopfuls of culture from
each growth-positive tube of azide
dextrose broth to the correspondingly
labeled tube of ethyl violet azide broth.
5 As transfers are made, place the newly
inoculated tubes of ethyl violet azide
broth in the positions in the rack
formerly occupied by the growth-
positive tubes of azide dextrose broth.
Discard the tubes of azide dextrose
broth culture.
6 Return the rack, containing 24-hour
growth-negative azide dextrose broth
tubes and newly-inoculated tubes of
ethyl violet azide broth, to the incubator.
Incubate 24 + 2 hours at 35° + 0. 5© C.
30-23
-------
MPN Methods
C 48-hour Operations
1 Remove the rack of tubes from the
incubator. Read and report results.
Growth, either in azide dextrose broth
or in ethyl violet azide broth, is a
positive test. Be sure to report the
results of the azide dextrose broth
medium under the "48" column for that
medium and the results of the ethyl
violet azide broth cultures under the
"24" column for that medium.
2 Any 48-hour growth-positive cultures
of azide dextrose broth are to be
transferred (three loopfulls) to ethyl
violet azide broth. Discard all 48-hour
growth-negative tubes of azide dextrose
broth and all 24-hour growth-positive
tubes of ethyl violet azide broth.
3 Incubate the 24-hour growth-negative
and the newly-inoculated tubes of ethyl
violet azide broth 24 + 2 hours at 3 5°
+ 0. 5° C.
2 Codify results and determine fecal
streptococci per 100 ml.
REFERENCES
1 Standard Methods for the Examination of
Water and Wastewater (12th ed).
Prepared and published jointly by
American Public Health Association,
American Water Works Association,
and Water Pollution Control
Federation. 1965.
2 Geldreich, E.E., Clark, H.F., Kabler,
P.W., Huff, C.B. and Bordner, R.H.
The Coliform Group II. Reactions
in EC Medium at 45QC. Appl.
Microbiol. 8:347-348. 1958.
3 Geldreich, E.E., Bordner, R.H., Huff,
C.B., Clark, H. F. and Kabler, P.W.
Type Distribution of Coliform Bacteria
in the Feces of Warm-Blooded Animals
J. Water Pollution Control Federation.
34:295-301. 1962.
D 72-hour Operations
4 Recommend Proc. for the Bacteriological
1 Read and report growth results of all Examination of Sea Water and Shellfish
tubes of ethyl violet azide broth 3rd Edition, American Public Health
Association. 1962.
2 Discard all growth-positive cultures
and all 48-hour growth-negative
cultures.
3 Reincubate any 24-hour growth-negative
cultures in ethyl violet azide broth 24
+ 2 hours at 35° + 0.5°C.
E 96-hour Operations
Read and report growth results of any This outline was prepared by H. L. Jeter,
remaining tubes of ethyl violet azide Director, National Training Center, FWQA,
broth. Cincinnati, OH 45226.
30-24
-------
MEMBRANE FILTER LA BORA TOR Y A ND FIELD PROCEDURES
I BASIC PROCEDURES
A Introduction
Successful application of membrane filter
methods requires development of good
routine operational practices. The detailed
basic procedures described in this Section
are applicable to all membrane filter
methods in water bacteriology for filtra-
tion, incubation, colony counting, and
reporting of results. In addition, equip-
ment and supplies used in all membrane
filter procedures are described here and
not repeated elsewhere in such detail.
Workers using membrane filter methods
for the first time are urged to become
thoroughly familiar with these basic pro-
cedures and precautions.
B General Supplies and Equipment List
Table 1 is a check list of materials.
C "Sterilizing" Media
Set tubes in a boiling waterbath for 10
minutes. This method suffices for medium
in tubes up to 25 X 150 mm.
Alternately, heat coliform media to the
first bubble of boiling. Stir the medium
frequently if direct heat is used, to avoid
charring the medium.
Do not autoclave.
D General Laboratory Procedures with
Membrane Filters
1 Prepare data sheet
Show sample identification, test per-
formed including media and methods,
sample filtration volumes, and the
bench numbers assigned to individual
membrane filters.
2 Disinfect the laboratory bench surface.
Use a suitable disinfectant solution and
allow the surface to dry before
proceeding.
3 Set out culture containers in an
orderly arrangement.
4 Label the culture containers.
Numbers correspond with the filter
numbers shown on the data sheet.
5 Place one sterile absorbent pad in
each culture container, unless an
agar medium is being used.
Use sterile forceps for all manipulations
of absorbent pads and membrane filters.
Forceps sterility is maintained by stor-
ing the working tips in about 1 inch of
methanol or ethanol. Because the
alcohol deteriorates the filter, dissipate
it by burning before using the forceps.
Avoid heating the forceps in the burner
as hot metal chars the filter.
6 Deliver enough culture medium to
saturate each absorbent pad, using a
sterile pipette.
Exact quantities cannot be stated be-
cause pads vary. Sufficient medium
should be applied so that when the
culture container is tipped, a good-sized
drop of culture medium freely drains out
of the absorbent pad.
When an agar medium is used, absor-
bent pads are not used. The amount of
medium should be sufficient to make a
layer approximately 1/8" deep in the
culture container. In the 50 mm
NOTE- Mention of commercial products and manufacturers does not imply endorsement by
the FWPCA and the U.S. Department of the Interior.
W. BA. mem. 81g. 8.68
31-1
-------
Membrane Filter Laboratory and Field Procedures
Table 1 EQUIPMENT. SUPPLIES AND MEDIA
Item
Funnel unit assemblies
Ring stand, with about a 3" split ring, to
support the filtration funnel
Forceps, curved-end round tipped,
special type for MF work
Methanol, in small wide-mouthed bottles,
about 20 ml for sterilizing forceps
Suction flasks, glass, 1 liter, mouth to
fit No 8 stopper
Rubber tubing, 2-3 feet, to connect
suction flask to vacuum services, latex
rubber 3/ 16" I D by 3/32" wall
Pinch clamps strong enough for tight
compression of rubber tubing above
Pipettes, 10 ml, graduated, Mohr type,
sterile, dispense 10 per can per working
space per day (Resterilize dally to
meet need)
Pipettes, 1 ml, graduated, Mohr type,
sterile dispense 24 per can per working
space per day (Resterilize daily to
meet need)
Pipette boxes, sterile, for 1 ml and
10 ml pipettes (sterilize above pipettes
in these boxes)
Cylinders, 100 ml graduated, sterile,
(resterilize daily to meet need)
Jars, to receive used pipettes
Gas burner, Bunsen or similar
laboratory type
Wax pencils, red, suitable for writing
on glass
Sponge in dilute iodine, to wipe down the
desk tops
M«mbraD« flUara (whji* grid
m*rk«d atorll* and
por« b]m for microbiologics)
of nur)
Absorbent pads for nutrient,
(47 mm in diameter), sterile,
in units of 10 pads per package.
Prtri dishes, disposable, plastic,
50 X J2 mm, sterile
Waterbath incubator 45 5 + 5°C
Vegetable criHpers, or cake boxes,
plastic, with tight fitting covers, for
membrane filter incubations
lrluorescent lamp, with extension
cord equipped with a simple lens
of about 4X magnification.
Ring stand uuh clamps, utilit} tvpe
Half-round glass paper ueights for
colom counting, with lower half of a
2-oz melal ointment box
Hand tall\, single unit acceptable, hand
Or desk t\pt»
Si« ieosoopu (dissci non) microscope
magnification of 10\ or 15X, prefer-
able bincrulat wide field t*pe
Standard Tests
M-Endo
Broth
X
X
X
X
X
X
X
X
X
X
X
X
X
X
L.E.S.
Coliform
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Delayed
Coliform
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Nonstandard Tests
Fecal
Coliform
X
X
X
X
X
X
X
X
X
X
X
X
X
Fecal
Streptococcus
r fied
' est
X
X
X
X
X
X
X
X
X
2
-------
Membrane Filter Laboratory and Field Procedures
Table 1 EQUIPMENT, SUPPLIES AND MEDIA (Cont'd)
Standard Tests
Nonstandard Tests
Item
M-Endo
Broth
L E S
CoLiform
Delayed
Coliform
Fecal
Coliform
Fecal
Streptococcus
Verified
Test
'iactenological inoculating needle
Wire racks for culture tubes, 10
openings b> five openings preferred,
dimensions overall approximately
6" X I 2 1
Phenol Red Lactose Broth in
JO X 150 mm fermentation tubes with
metal caps, 10 ml per tube
Eosin Methylene Blue Agar (Levlne)
in petri plates, prepared ready for use
Nutrient agar slants, in screw capped
lubes, 16 X 126 mm
Gram stain solutions, 4 solutions per
complete eet
Microscope, compound, binocular,
with oil immersion lens, microscope
lamp and immersion oil
Microscope slides, new clean,
1" X 3" size
Water proof plastic bags 3 X7 1/ 4"
for fecal coliform culture dish
incubation
M-Endo medium, MFdehydrated medium
in 25 X 05 mm flat bottomed screw-
capped glass viale, 1 44 g per tube,
sufficient for 30 m! of medium
Ethanol, 95% in small bottles or
screw-capped tubes, about 20 ml
per tube
Sodium benzoate solution, 12% aqueous,
in 25 x 150 mm screw-capped tubes,
about 10 ml per tube
L E S Endo Agar MF, dehydrated
M-Fndo medium, 0 36 g per
25 X 95 mm flat bottomed screw-
capped glass wal, plus 0 45 g agar,
for 30 ml
Lactose L*tur)l Sulfate Tryptose Broth
in 25 X 150 mm test tube without
included gas tube, about 25 ml, for
enrichment in L E S method
M-FC Broth for fecal coliform, dehy-
drated medium in 25 X 95 mm flat
bottomed screw-capped glass viala,
1 23 g per tube, sufficient for 30 ml
of culture medium
Rosolic acid, 1% solution, in 0 3N
NaOH, In 25 X 150 mm flat bottomed
screw-capped tubes, about 5 ml per
tube, freshly prepared
M-Enterococus Agar, dehydrated
medium in 25 X 150 mm screw-
capped tubes sufficient for 30 ml,
1 26 g per tube
Dilution bottles, 6-ox preferable
boro"Silicate glass, with screw-cap
(or rubber stopper protected by
paper) each containing 99 ml of
phosphate buffered dilution water
Electric hot plate surface
Beakers 400 - 600 ml (for water -
bath in preparation of membrane
filter culture mrdia)
Crucible tonus to be used at electric
hot plates, for n moval of hoi tubes
of culture mi dia from boiling
uat rrbath
3
-------
Membrane Filter Laboratory and Field Procedures
plastic culture containers, this corres-
ponds to approximately 6-8 ml of culture
medium.
7 Organize supplies and equipment for
convenient sample filtration. In
training courses, laboratory instructors
will suggest useful arrangements,
eventually the individual will select a
system of bench-top organization most
suited to his own needs. The important
point in any arrangement is to have all
needed equipment and supplies con-
veniently at hand, in such a pattern as
to minimize lost time in useless motions.
8 Lay a sterile membrane filter on the
filter holder, grid-side up, centered
over the porous part of the filter
support plate.
Membrane filters are extremely deli-
cate and easily damaged. For manipula-
tion, the sterile forceps should always
grasp the outer part of the filter disk,
outside the part of the filter through
which the sample passes.
9 Attach the funnel element to the base of
the filtration unit.
To avoid damage to the membrane filter,
the funnel element never should be
turned or twisted while being seated
and locked to the lower element of the
filter holding unit. Filter holding
units featuring a bayonet joint and lock-
ing ring to join the upper element to
the lower element require special care
on the part of the operator The lock-
ing ring should be turned sufficiently to
give a snug fit, but should not be
tightened excessively.
10 Shake the sample thoroughly.
11 Measure sample into the funnel with
vacuum turned off.
The primary objectives here are
1) accurate measurement of sample,
and 2) optimum distribution of colonies
on the filter after incubation. To meet
these objectives, methods of measure-
ment and dispensation to the filtration
31-4
assembly are varied with different
sample filtration volumes.
a With samples greater than 20 ml,
measure the sample with a sterile
graduated cylinder and pour it into
the funnel.
b With samples of 10 ml to 20 ml,
measure the sample with a sterile
10 ml or 20 ml pipette, and pipette
on a dry membrane in the filtration
assembly.
c With samples of 2 ml to 10 ml, pour
about 20 ml of sterile dilution water
into the filtration assembly, then
measure the sample into the sterile
buffered dilution water with a 10 ml
sterile pipette.
d With samples of 0.5 to 2 ml, pour
about 20 ml of sterile dilution
water into the funnel assembly, then
measure the sample into the sterile
dilution water in the funnel with a
1 ml or a 2 ml pipette.
e If a sample of less than 0. 5 ml is to
be filtered, prepare appropriate
dilutions in sterile dilution water,
and proceed as applicable in item c
or d above.
When dilutions of samples are needed,
always make the filtrations as soon
as possible after dilution of the sample,
this never should exceed 30 minutes.
Always shake sample dilutions
thoroughly before delivering measured
volumes.
12 Turn on the vacuum.
Open the appropriate spring clamp or
valve, and filter the sample.
13 Rinse the sample through the filter.
After all the sample has passed through
the membrane filter, rinse down the
sides of the funnel walls with at least
20 ml of sterile dilution water. Repeat
the rinse twice after all the first rinse
has passed through the filter. Cut off
suction on the filtration assembly.
After sample filtration a few droplets
of sample usually remain adhered to
-------
Membrane Filter Laboratory and Field Procedures
the funnel walls. Unless these droplets
are removed, the bacteria contained
in them will be a source of contamina-
tion of water samples. (In laboratory
practice the funnel unit is not routinely
sterilized between successive filia-
tions of a series). The purpose of the
funnel rinse is to flush all droplets of
a sample from the funnel walls to the
membrane filter. Extensive tests have
shown that with proper rinsing tech-
nique, bacterial retention on the funnel
walls is negligible.
14 Remove the funnel element of the filter
holding unit.
If a ring stand and split ring is used,
hang the funnel element on the ring,
otherwise place the funnel unit, inverted,
on the bench surface.
15 Take the membrane filter from the
filter holder and carefully place it,
^nd-side up on the medium.
Check that no air bubbles have been
trapped between the membrane filter
and the underlying absorbent pad or
agar. Relay the membrane if necessary.
16 Place in incubator after finishing
filtration series.
Invert the containers. The immediate
atmosphere of the incubating membrane
filter must be at or very near 100%
relative humidity.
17 Count colonies which have appeared
after incubating for the prescribed time.
A stereoscopic microscope magnifying
10-15 times and careful illumination
give best counts.
For reporting results, the computation is:
bacteria/100 ml =
No. colonies counted X 100
Sample volume filtered in ml
Example-
A total of 36 colonies grew after
filtering a 10 ml sample. The number
reported is.
36 colonies „„„ ,
— : X 100 - 360 per 100 ml
10 ml
II MF LABORATORY TESTS FOR
COL IFOR M GROUP
A Standard Coliform Test (Based on M-Endo
Broth MF)
Standard counts require two additions to the
general procedure. First is characteristic
medium. Second is the critical lighting
necessary to count the golden sheen
colonies of coliform bacteria.
1 Culture medium
a M-Endo Broth MF Difco 0749-02 or
the equivalent BBL M-Coliform
Broth 01-494
Preparation of Culture Medium
(M-Endo Broth) for Standard MP
Coliform Test
Yeast extract
1. 5
g
Casitone or equivalent
5. 0
g
Thiopeptone or equivalent
5. 0
g
Tryptose
10. 0
g
Lactose
12. 5
g
Sodium desoxycholate
0. 1
£
Dipotassium phosphate
4. 375
E
Monopotassium phosphate
1. 375
g
Sodium chloride
5. 0
g
Sodium lauryl sulfate
0. 05
g
Basic fuchsin (bacteriological)
1. (n
g
Sodium sulfite
2. 1
g
Distilled water (contain.,ng 1000 ml
20. 0 ml ethanol)
This medium is available in dehy-
drated form and it is recommended
that the commercially available
31-5
-------
Membrane Filter Laboratory and Field Procedures
medium be used in preference
to compounding the medium of
its individual constituents.
To prepare the medium for use,
suspend the dehydrated medium at
the rate of 48 grams per liter of
water containing ethyl alcohol at the
rate of 20 ml per liter.
As a time-saving convenience, it is
recommended that the laboratory
worker preweigh the dehydrated
medium in closed tubes for several
days, or even weeks, at one operation.
With this system, a large number
of increments of dehydrated
medium (e.g., 1.44 grams), suffi-
cient for some convenient (e.g. ,
30 ml) volume of finished culture
medium are weighed and dispensed
into screw-capped culture tubes,
and stored until needed.
A supply of distilled water containing
20 ml stock ethanol per liter is
maintained.
When the medium is to be used, it
is reconstituted by adding 30 ml of
the distilled water-ethanol mixture
per tube of pre-weighed dehydrated
culture medium.
b Medium is "sterilized" as directed
in I, C.
c Finished medium can be retained
up to 96 hours if kept m a cool,
dark place. Many workers prefer
to reconstitute fresh medium daily.
2 Filtration and incubation procedures are
as given m I, D.
Special instructions:
a For counting, use the wide field
binocular dissecting microscope, or
simple lens. For illumination, use
a light source perpendicular to the
plane of the membrane filter. A
small fluorescent lamp is ideal for
the purpose.
b Coliform colonies are red or pink
and have a "metallic" surface sheen
under reflected light which may cover
the entire colony, or it may appear
only in the center. Non-coliform
colonies range from colorless to
pink, but do not have the characteris-
tic sheen.
c Record the colony counts on the data
sheet, and compute tike coliform
count per 100 ml of sample.
B Standard Coliform Tests (Based on
L.E.S. Endo Agar)
The distinction of the L.E.S. count is a
two hour enrichment incubation on LST
broth. M-Endo medium is used as agar
rather than the broth.
1 Preparation of culture medium (L.E.S.
Endo Agar) for L.E.S. coliform test
a Formula from McCarthy, Delaney,
and Grasso'^
Bacto-Yeast Extract
1. 2
g
Bacto -Casitone
3. 7
g
Bacto -Thiopeptone
3. 7
g
Bacto-Tryptose
7. 5
g
Bacto-Lactose
9. 4
g
Dipotassium phosphate
3. 3
g
Monopotassium phosphate
1.0
g
Sodium chloride
3. 7
g
Sodium desoxycholate
0. 1
g
Sodium lauryl sulfate
0. 05
g
Sodium sulfite
1. 6
g
Bacto-Basic fuchsin
0. 8
g
Agar
15
g
Distilled water (containing
1000
ml
20 ml ethyl alcohol)
b To rehydrate the medium, suspend
51 grams in the water-ethyl alcohol
sodium.
c Medium is "sterilized" as directed in
I, C.
d Pour 4-6 ml of melted L.E S. Agar
into the smaller half of the container
The liquid medium should be at
45-50°C. Allow the medium to cool
and solidify.
31-6
-------
Membrane Filter Laboratory and Field Procedures
e If the containers with medium are
stored in the refrigerator in the dark,
they are usable over a two week
period.
2 Procedures for filtration and incubation
a Lay out the culture dishes in a row
or series of rows as usual.
b Place one sterile absorbent pad in
the larger half of each container.
Use sterile forceps for all manipula-
tions of the pads. (Agar occupies
smaller half )
c Using a sterile pipette, deliver
enough single strength lauryl sulfate
tryptose broth to saturate the pad
only. Excess interferes.
d Follow general procedures for
filtering in I, D. Place filters on
pad with lauryl sulfate tryptose broth.
e Upon completion of the filtrations,
invert the culture containers and
incubate at 35°C for 2+1/2 hours.
3 2-hour procedures
a Transfer the membrane filter from
the enrichment pad in the upper half
to the agar medium in the lower half
of the container. Carefully roll the
membrane onto the agar surface to
avoid trapping air bubbles beneath
the membrane.
b Removal of the used absorbent pad
is optional.
c The container is inverted and incu-
bated 22 hours at 35°C.
4 Counting procedures are as in I, D.
5 L. E. S. Endo Agar may be used as a
single-stage medium (no enrichment
step) in the same manner as M-Endo
Broth, MF.
C Delayed Incubation Coliform Test
The delayed coliform count requires two
media and permits 24-72 hour delay be-
fore incubating for counts.
1 Preparation of culture media for de-
layed incubation coliform test
a Preservative media
M-Endo Broth base
To a 30 ml tube of M-Endo Broth MF
prepared in accordance with direc-
tions in II, A, 1 of this outline, add
1.0 ml of 12% aqueous solution of
sodium benzoate after sterilizing.
LES MF Holding Medium - Coliform.
Dissolve 12.7 grams in 1 liter of dis-
tilled water. No heating is necessary.
Final pH 7 1+0.1.
b Growth media
M-Endo Broth MF is used, prepared
as described in II, A, 1 earlier in
this outline. Alternately, L.E.S.
Endo Medium may be used.
2 General filtration followed is in I, D.
Special procedures are:
a Transfer the membrane filter from
the filtration apparatus to a pad
saturated with benzoated M-Endo
Broth.
b Close the culture dishes and store
membrane filters at room tempera-
ture. If the cultures are transmitted
to a central laboratory for conclusion
of test, then check the identification
markings on each culture container
against the transmittal sheet. Each
culture and the transmittal sheet
should show at least-
The date the sample was collected
and filtered
The source of sample
Serial number of filtration
Quantity of water filtered.
31-7
-------
Membrane Filter Laboratory and Field Procedures
c Place the culture containers and
transmittal sheet in a mailing carton
and immediately send it to the central
laboratory. Transportation time
should not exceed 3 days, and prefer-
ably less.
d On receipt in the central laboratory,
unpack mailing carton, and lay out
the culture containers on the labora-
tory bench.
D Verified Membrane Filter Coliform Test
This procedure applies to identification
of colonies growing on Endo-type media
used for determination of total coliform
counts. Isolates from these colonies
are studied for gas production from
lactose and typical coliform morphology.
In effect, the procedure corresponds with
the Completed Test stage of the multiple
fermentation tube test for coliforms.
e Remove the tops from the culture
containers. Using sterile forceps,
remove each membrane and its
absorbent pad to the other half of
the culture container. (See j, below,
for alternate procedure.)
f With a sterile pipette or sterile
absorbent pad, remove preservative
medium from the culture
container.
g Place a sterile absorbent pad in
each culture container, and deliver
enough freshly prepared M-Endo
Broth to saturate each pad.
h Using sterile forceps, transfer the
membrane to the new absorbent pad
containing M-Endo Broth. Place the
membrane carefully to avoid entrap-
ment of air between the membrane
and the underlying absorbent pad.
Discard the absorbent pad containing
preservative medium
1 After incubation 24 hours at 35°C,
count colonies as in the above section
A, 2.
j If L. E. S. Endo Agar is used, the
steps beginning with (e) above are
omitted, and the membrane filter is
removed from the preservative
medium and transferred to a fresh
culture container with L. E. S. Endo
Agar, incubated, and colonies
counted in the usual way.
Procedure:
1 Select a membrane filter bearing
several well-isolated coliform-type
colonies.
2 Using sterile technique, pick all colonies
in a selected area with the inoculation
needle, making transfers into tubes of
phenol red lactose broth (or lauryl
sulfate tryptose lactose broth). Use
a data sheet similar to the sheet titled
"Verified Membrane Filter Test" in
the laboratory section of this manual.
Record the interpretation of each colony,
"C" for colonies having the typical color
and sheen of coliforms, "NC" for colonies
not conforming to coliform colony appear-
ance on Endo-type media.
3 Incubate the broth tubes at 35°C.
4 At 24 hours
a Read and record the results from the
lactose broth fermentation tubes.
The following code is suggested*
Code Result
O No indication of acid or gas
production, either with or
without evidence of growth.
A Evidence of acid but not gas
(applies only whenapH indicator
is included in the broth medium)
G Growth with production of gas.
If pH indicator is used, use
symbol AG to show evidence of
acid. Gas in any quantity is a
positive test.
31-8
-------
Membrane Filter Laboratory and Field Procedures
b Tubes not showing gas production are
returned to the 35°C incubator.
c Gas-positive tubes are transferred
as follows
1) Prepare a streak inoculation on
EMB agar for colony isolation.
E Fecal Coliform Count (Based on M-FC
Broth Base)
The count depends upon growth on a
special medium at 44 5 + .5°C.
1 Preparation of Culture Medium (M-FC
Broth Base) for Fecal Coliform Count
2) Inoculate a single nutrient agar
slant from each gas-positive tube.
3) Incubate at 35°C.
5 At 48 hours
a Read and record results of lactose
broth tubes which were negative at
24 hours and were returned for
further incubation.
b Gas-positive cultures are subjected
to further transfers as in 4c, above.
Gas-negative cultures are discarded
without further study, they are
coliform -negative.
c Examine the cultures transferred to
EMB agar plates and to nutrient agar
slants, as follows
1) Examine the EMB agar plate for
evidence of purity of culture, if
the culture represents more than
one colony type, discard the
nutrient agar culture and reisolate
each of the representative colonial
types on the EMB plate and resume
as with 4c above for each isolation.
If purity of culture appears evident,
continue with c (2) below.
2) Prepare a smear and Gram stain
from each nutrient agar slant
culture. The Gram stain should
be made on a culture not more than
24 hours old. Examine under oil
immersion for typical coliform
morphology, and record results.
a Composition
Tryptose
Proteose Peptone No. 3
Yeast extract
Sodium chloride
Lactose
Bile salts No. 3
Rosolic acid* (Allied
Chemical)
Aniline blue (Allied Chemical) 0. 1 g
10.0 g
5.0 g
3. 0 g
5.0 g
12.5 g
1.5 g
10.0 ml
Distilled water
1000 ml
b To prepare medium dissolve
37. 1 grams in a liter of distilled
water which contains 10 ml of 1%
rosolic acid in 0. 2 N NaOH.
Fresh solutions of rosolic acid give
best results. Discard solutions
which have changed from dark red
to orange.
c To sterilize, heat to boiling as
directed in I, C.
d Prepared medium may be retained
up to 4 days in the dark at 2-8°C
2 Special supplies
Small water proof plastic sacks capable
of being sealed against water with
capacity of 3 to 6 culture containers.
6 At 72 hours.
Perform procedures described in 5c
above, and record results.
7 Coliform colonies are considered veri-
fied if the procedures demonstrate a
pure culture of bacteria which are gram
negative nonspore-forming rods and
produce gas from lactose at 35 C.
3 Filtration procedures are as given in
I, D.
^Prepare 1% solution of rosolic acid in 0. 2 N
NaOH. This dye is practically insoluble in
water.
31-9
-------
Membrane Filter Laboratory and Field Procedures
4 Elevated temperature incubation
a Place fecal coliform count membranes
at 44. 5 + 0 5°C as rapidly as
possible.
Filter membranes for fecal coliform
counts consecutively and immediately
place them in their containers Insert
as many as six containers into the sacks
and seal Tear off the perforated top,
grasp the side wires, and twirl the sack
to roll the open end inside the folds of
sack Then submerge the sacks with
containers beneath the surface of a
44. 5 + 5°C waterbath
1 Preparation of the culture medium
a Formula (The Difco formula is
shown, but equivalent constitutents
from other sources are equally
acceptable).
Bacto tryptose
20. 0
g
Bacto yeast extract
5 0
g
Bacto dextrose
2 0
g
Dipotassium phosphate
4. 0
g
Sodium Azide
0. 4
g
Bacto agar
10 0
g
2, 3, 5, Triphenyl
0. 1
g
tetrazolium chloride
b Incubate for 22 + 2 hours.
5 Counting procedures
Examine and count colonies as follows
a Use a wide field binocular dissecting
microscope with 5 - 10X magnification.
b Low angle lighting from the side is
advantageous.
c Fecal coliform colonies are blue,
generally 1-3 mm in diameter
d Record the colony counts on the data
sheet, and report the fecal conform
count per 100 ml of sample
(I, D, 17 illustrates method)
b The medium is prepared by rehydra
tion at the rate of 42 grams per
1000 ml of distilled water. It is
recommended that the medium in
dehydrated form be preweighed and
dispensed into culture containers
(about 25 X 150 mm) in quantities
sufficient for preparation of 30 ml
of culture medium (1. 26 g per tube).
c Follow I, C, for "sterilizing"
heat medium. The medium
should be cooled 45-50°C
before being dispensed into
culture containers.
2 List of apparatus, materials, as
given in Table I.
3 Procedure, in general, as given
m I.
HI TESTS FOR FECAL STREPTOCOCCAL
GROUP-MEMBRANE FILTER METHOD
A 48 hour incubation period on a choice of two
different media, giving high selectivity for
fecal streptococci, are the distinctive features
of the tests.
A Test for Members of Fecal Streptococcal
(Tentative, Standard Methods) M-Entero-
coccus Agar Medium
Special instructions
a To prepare agar plates, open the
containers, and pour 5-8 ml of
sterile melted M-Enterocococcus
agar into each Replace the covers
of the culture containers, and allow
them to stand until the agar has
solidified.
31-10
-------
Membrane Filter Laboratory and Field Procedures
b Incubate for 48 hours, inverted, with
100% relative humidity, after filtra-
tions are completed. If the entire
incubator does not have saturated
humidity, acceptable conditions can
be secured by placing the cultures
in a tightly closed container with
wet paper, towels, or other moist
material.
c After incubation, remove the cultures
from the incubator, and count all
colonies under wide field binocular
dissecting microscope with magnifica-
tion set at 10X or 20X. Fecal strepto-
coccus colonies are 0.5 - 2 mm in
diameter, and flat to raised smooth, and
vary from pale pink to dark red in color.
d Report enterococcus count per 100 ml
of sample. This is conveniently
computed.
No. fecal streptococci per 100 ml =
No. fecal streptococcus colonies counted w
* y inn
Sample filtration volume in ml
B Test for Members of Fecal Streptococcal
Group based on KF-Agar
1 Preparation of the culture medium
a Formula (The dehydrated formula
of Bacto 0496 is shown, but equi-
valent constituents from other sources
are acceptable). Formula is in grams
per liter of reconstituted medium.
Bacto proteose peptone #3
10. 0
g
Bacto yeast extract
10.0
i
Sodium chloride (reagent grade)
5.0
g
Sodium glycerphosphate
10. 0
g
Maltose (CP)
20. 0
g
Lactose (CP)
1 0
g
Sodium azide (Eastman)
0. 4
g
Sodium carbonate
0. 636
g
(Na2C03 reagent grade)
Brom ere sol purple
0. 015
g
(water soluble)
Bacto agar
20.0
g
2, 3, 5-Triphenyl tetrazolium chloride
reagent (TPTC)
This reagent is prepared by making
a 1% aqueous solution of the above
chemical passing it through a Seitz
filter or by bringing to a boil. It can
be kept in the refrigerator in a screw-
capped tube until used.
b The dehydrated medium described
above is prepared for laboratory
use as follows*
Suspend 7. 64 grams of the dehydrated
medium in 100 ml of distilled water
in a flask with an aluminum foil cover.
Place the flask in a boiling waterbath,
melt the dehydrated medium, and
leave in the boiling waterbath an
additional 5 minutes.
Cool the medium to 50°-60°C, add
1.0 ml of the TPTC reagent, and
mix.
For membrane filter studies, pour
5-8 ml in each 50 ml glass or plastic
culture dish or enough to make a
layer approximately 1/8" thick.
For plate counts, pour as for stand-
ard agar plate counts.
Note Plastic dishes containing
media may be stored in a dark, cool
place up to 30 days without change
in productivity of the medium, pro-
vided that no dehydration occurs.
Plastic dishes may be incubated in
an ordinary air incubator. Glass
dishes must be incubated in an
atmosphere with saturated humidity.
2 Apparatus, and materials as given in
Table 1.
3 General procedure is as given in I.
Special instructions
a To prepare plates open the containers,
and pour 5-8 ml of sterile melted
KF-Agar into each. Replace the
31-11
-------
Membrane Filter Laboratory and Field Procedures
covers of the culture containers,
and allow them to stand until the
agar has solidified.
b Incubate 48 hours, inverted with
100% relative humidity after
filtration.
c After incubation, remove the
cultures from the incubator, and
count colonies under wide field
binocular dissecting microscope,
with magnification set at 10X or 20X.
Fecal streptococcus colonies are
pale pink to dark wine-color. In
size they range from barely visible
to approximately 2 mm in diameter.
Colorless colonies are not counted.
d Report fecal streptococcus count
per 100 ml of sample. This is
computed as follows
No. fecal streptococci per 100 ml =
No. fecal streptococcus colonies
—5 ^—TTl—7 i r~ x 100
Sample filtration volume in ml
C Confirmation of Streptococcus Colonies
1 Confirmation of colony identification
may be required in waters containing
large numbers of Micrococcus organisms.
This has been noted particularly with
bathing waters, but the problem is by
no means limited to such waters.
2 A confirmatory procedure is described
in "Standard Methods for the Exami-
nation of Water and Wastewater, 12th
ed, (1965), p 619. The worker should
use this reference for the step-by-step
procedure.
IV PROCEDURES FOR USE OF MEMBRANE
FILTER FIELD UNITS
A Culture Media
1 The standard coliform media used with
laboratory tests are used.
2 To simplify field operations, it is
suggested that the medium be sent to
the field, preweighed, in vials or
capped culture tubes. The medium then
requires only the addition of a suitable
volume of distilled water-ethanol prior
to sterilization.
3 Sterilization procedures in the field
are the same as for laboratory methods.
4 Laboratory preparation of the media,
ready for use, would be permissible
provided that the required limitations
on time and conditions of storage are
met.
B Operation of the Sabro Field Unit
1 Equipment and materials
Sabro field unit
Membrane filters
Absorbent pads for nutrient
Culture containers
M-Endo Broth MF or L. E. S. Endo
Medium
Provision for heating water (optional)
Source of electricity
2 Procedure ( Based on M-Endo Broth MF)
a Connect the electric cord to the
power source and to Sabro field
unit. After about 15 minutes check
the temperature in the incubator
drawer. The desired temperature is
35°C (95°F). If the temperature is
too low it can be increased by turn-
ing the thermostat adjustment screw
counterclockwise. This screw is
located at the front on the recessed
divider between the two incubator
drawers. To lower temperature,
turn the adjustment screw clockwise.
b Review the supply of expendable
materials to be used with the unit
31-12
-------
Membrane Filter Laboratory and Field Procedures
and secure replacements as needed
(culture containers, medium, mem-
brane filters, absorbent pads for
nutrient, fuel, etc.).
c Sterilize the funnel unit by one of
the following procedures.
1) Immerse the equipment 30 seconds
in water at 170°F (78°C).
2) Immerse the equipment 2 minutes
in boiling water (Preferred at SEC).
3) Flame-sterilize membrane filter
holder inside and both ends of
funnel (suggested by manufacturer).
d Lay in a row all the culture containers
to be used in the filtration series,
and number the containers to corres-
pond with numbers of the data sheet.
e Place one sterile absorbent pad in
each culture container. Use sterile
forceps for all manipulation of
absorbent pads and filters.
Using sterile pipette deliver enough
culture medium to saturate each
absorbent pad. The amount of
culture medium required is approxi-
mately 2 ml, but cannot be precisely
stated. Sufficient medium should
be applied, that when the culture
container is tipped, a good-sized
drop of culture medium freely drains
out of the absorbent pad.
Using sterile forceps, place a mem-
brane filter, grid-side up, on the
MF receptacle of the funnel unit.
Place the funnel portion over the
membrane, and clamp the unit with
the spring clamp provided with the
portable kit.
Pour the water sample into the
funnel. The sample can be measured
in a graduated cup or cylinder pre-
viously sterilized by 2 minutes
immersion in boiling water and cooled
before use.
l Connect the tubing of the vacuum
pump to the receptable on the base
of the filter unit and draw the sample
through the membrane.
j Disassemble the funnel unit and with
sterile forceps transfer the membrane
filter grid-side up to the appropriate
culture container. The membrane
should be "rolled on" the absorbent
pad containing culture medium, to
prevent entrapment of air between
the pad and the membrane filter.
k Repeat steps g - j for additional
filtrations of the same or different
sampling volumes for the water
being tested.
1 After completion of the last filtra-
tion from any one sample, resterilize
the funnel unit by one of the proce-
dures described in instruction 2c.
m After completion of filtration, place
the culture container (with membrane
position grid-side down) in the
incubator drawers.
n Allow the cultures to incubate
20-24 hours.
o Remove the cultures from the
incubator and count coliform colonies.
Operation of Millipore Field Monitor Unit
1 Equipment and materials
Millipore field monitor with sampling
tube
Metal syringe with bypass valve
Sampling container (glass, metal, or
paper measuring cup)
M-Endo Broth MF, 1.5 X, freshly
prepared or ampouled medium
Sterile pipettes
Field incubator
31-13
-------
Membrane Filter Laboratory and Field Procedures
2 Procedure
a Remove the rubber caps from the
field monitor.
b Assemble the sampling tube, field
monitor, and metal syringe as
follows
Tightly insert the lateral nozzle of
the syringe bypass valve in the
opening of the field monitor nearest
the screen side (i.e., with the
membrane filter directed away from
the bypass valve).
Insert the plastic adapter of the
sampling tube in the opening of the
field monitor nearest the membrane
filter.
c Fill the sampling container with the
volume of water to be tested.
If the sampling container is glass or
metal it is recommended that it be
previously sterilized by 2 minutes
immersion in boiling water, then
cooled before use.
Paper measuring cups, if preferred,
should be rinsed repeatedly in the
water being tested, before the actual
sample is filtered.
d Insert the sampling tube into the
cup and draw out all the water by
pumping the syringe. Filtrate water
is expelled from the end of the bypass
valve in this procedure. Caution is
required to direct this syringe in
such a way that expelled water does
not create a mess.
e Invert the syringe (membrane side
up) and draw the remaining water
through the filter
f Apply culture medium as follows
Remove the sampling tube from the
field monitor.
Apply freshly prepared 1. 5x M-Endo
Broth MF with a sterile dropping
pipette (sterilize by 2 minutes im-
mersion in boiling water). The tip
of the pipette should be introduced
into the opening of the field monitor
away from the membrane filter, the
medium should be delivered by a series
of short pulsing contractions of the
pipette bulb. Alternately, if ampouled
medium is used, break the tips off an
ampoule, and use the ampoule like a
pipet in delivering culture medium to
the absorbent pad beneath the mem-
brane filter in the assembly.
g Remove the monitor from the syringe,
replace the rubber caps, and place
inverted in the field incubator.
h Incubate the cultures 22-24 hours,
then remove from the incubator and
count coliform and noncoliform
colonies m the usual way.
D Operation of Water Testing Kit, Bacterio-
logical (This is the Millipore kit developed
for military use, now commercially
available)
1 Supporting supplies and equipment are
the same as for the laboratory procedures.
2 Set the incubator voltage selector switch
to the voltage of the available supply,
turn on the unit and adjust as necessary
to establish operating incubator tem-
perature at 35 +0. 5°C.
3 Sterilize the funnel unit assembly by
exposure to formaldehyde or by
immersion in boiling water. If a labor-
atory autoclave is available, this is
preferred.
Formaldehyde is produced by soaking
an asbestos ring ( in the funnel base)
with methanol, igniting, and after a
few seconds of burning, closing the
unit by placing the stainless steel flask
over the funnel and base. This results
in incomplete combustion of the methanol,
whereby formaldehyde is produced.
Leave the unit closed for 15 minutes to
allow adequate exposure to formaldehyde.
31-14
-------
Membrane Filter Laboratory and Field Procedures
4 Filtration and incubation procedures
correspond with laboratory methods.
5 The unit is supplied with a booklet con-
taining detailed step-by-step operational
procedures. The worker using the
equipment should become completely
versed in its contents and application.
E Counting of Colonies on Membrane Filters
1 Equipment and materials
Membrane filter cultures to be examined
Illumination source
Simple lens, 2X to 6X magnification
Hand tally (optional)
2 Procedure
a Remove the cultures from the incuba-
tor and arrange them in numerical
sequence.
b Set up illumination source as that
light will originate from an area
perpendicular to the plane of mem-
brane filters being examined. A
small fluorescent lamp is ideal for
the purpose. It is highly desirable
that a simple lens be attached to the
light source
c Examine results Count all coliform
and noncoliform colonies. Coliform
colonies are pink to deep red and
have a "metallic" surface sheen
under reflected light, which may
cover the entire colony or may
appear only on the center
Noncoliform colonies range from
colorless to pink or red, but do not
have the characteristic "metallic"
sheen.
d Enter the colony counts in the data
sheets.
e Enter the coliform count per 100 ml
of sample for each membrane having
a countable number of coliform
colonies Computation is as follows
No. coliform per 100 ml z
No. coliform colonifes on MF x
No milliliters sample filtered
REFERENCES
1 Standard Methods for the Examination of
Water and Wastewater. APHA, AWWA,
WPCF. 12th Edition. 1965.
2 McCarthy, J. A., Delaney, J. E., and
Grasso, R.J. Measuring Coliforms
in Water. Water and Sewage Works.
196 1: R-426-31. 196 1.
This outline was prepared by H. L. Jeter,
Director, National Training Center,
FWPCA, Cincinnati, OH 45226.
31-15
-------
DISSOLVED OXYGEN DETERMINATION (DO) - I
Azide Modification, Iodometric Titration
I The Dissolved Oxygen determination is
a very important water quality criteria for
many reasons:
A Oxygen is an essential nutrient for all
living organisms. Dissolved oxygen is
essential for survival of aerobic
organisms and permits facultative
organisms to metabolize more effectively.
Many desirable varieties of macro or
micro organisms cannot survive at
dissolved oxygen concentrations below
certain minimum values. These values
vary with the type of organisms, stage
in their life history, activity, and other
factors.
B Dissolved oxygen levels may be used as
an indicator of pollution by oxygen
demanding wastes. Low DO concen-
trations are likely to be associated with
low quality waters.
C The presence of dissolved oxygen
prevents or minimizes the onset of
putrefactive decomposition and the
production of objectionable amounts of
malodorous sulfides, mercaptans,
amines, etc.
D Dissolved oxygen is essential for
terminal stabilization wastewaters.
High DO concentrations are normally
associated with good quality water.
E Dissolved oxygen changes with respect
to time, depth or section of a water
mass are useful to indicate the degree
of stability or mixing characteristics
of that situation.
F The BOD or other respirometnc test
methods for water quality are commonly
based upon the difference among an
initial and final DO determination for a
given sample time interval and con-
dition. These measurements are
useful to indicate
1 The rate of biochemical activity in
terms of oxygen demand for a
given sample and conditions.
2 The degree of acceptability
(a bioassay technique) for bio-
chemical stabilization of a given
microbiota in response to food,
inhibitory agents or test conditions.
3 The degree of instability of a
water mass on the basis of test
sample DO changes over an
extended interval of time.
4 Permissible load variations in
surface water or treatment units
in terms of DO depletion versus
time, concentration, or ratio of
food to organism mass, solids, or
volume ratios.
5 Oxygenation requirements
necessary to meet the oxygen
demand in treatment units or
surface water situations.
G The DO test is the only chemical test
included in all Water Quality Criteria,
Federal, State, Regional or local.
II FACTORS AFFECTING THE DO
CONCENTRATION IN WATER
A Physical Factors*
1 DO solubility in water for an
air/water system is limited to
about 9 mg DO/liter of water at
20° C. This amounts to about
0. 0009% as compared to 21% by
weight of oxygen in air.
2 Transfer of oxygen from air to
water is limited by the interface
area, the oxygen deficit, partial
pressure, the conditions at the
CH. O. do. 31. 7. 69
32-1
-------
Dissolved Oxygen Determination (DO) - I
interface area, mixing phenomena
and other items.
Two factors tend to confuse the
reoxygenation pattern in water.
a The transfer of oxygen m air
to oxygen in water is a
relatively inefficient process
in terms of the mass of oxygen
in air at the interface and mass
of oxygen transferred across
the interface into the water.
Diffused air aeration commonly
shows that 3 to 6% of the
oxygen in air fed into the
bottom of an activated sludge
aerator may be transferred to
the liquid. Reported ranges
vary from 1 to 30% or higher
depending upon factors listed
earlier.
b Although the process is
mefficient.it occurs very
rapidly. The very low
solubility of oxygen in water
doesn't require transfer of a
large mass of oxygen per unit
volume of water to change the
DO concentration from 0 to 90%
of saturation. Therefore, the
DO may be increased very
quickly by increasing the air-
water interface area for
samples having low % DO
saturation values. In fact, it
is very difficult to add reagents
to samples containing no DO
without transfer of small
quantities of oxygen into the
sample via the small surface
area exposed. It is common
to observe no DO in a final
clarifier supernatant approaching
the discharge weirs while
there may be 3 to 6 mg DO/1
in the effluent channel after
discharge in a thin layer over
the weirs. The large oxygen
deficit for samples containing
low percentage saturation
values increases the efficiency
of transfer and decreases time
and energy required to raise
the DO. At about 90% DO
saturation, transfer efficiency
is low and time and energy
requirements are much greater
per unit increase in DO.
c A low DO sample may be raised
to 7 0 to 90% DO saturation by:
shaking a partially filled
bottle vigorously for 15 to 30
seconds, pouring rapidly from
one container to another 4 to
6 times, allowing a container
about 80% filled with low DO
water to stand for 2 to 3 days.
Diffused air aeration often is
a first consideration for
polluted water. This is
desirable because the dust,
fumes, aerosols, and water
solubles in the air are small
in relation to the water con-
taminants. A distilled or
other high quality water is
likely to be dirtied by aeration.
Air at ambient temperature
weighs approximately 1.1 g/1
and contains about 230 mg of
oxygen per liter. If 50% or
115 mg of this was transferred
to water the net effect would
increase the DO of about
14 liters of water from 0 to
8 mg per liter. This could be
accomplished in 2 to 3 days
of storage or in a few seconds
of mixing. With high quality
water such as BOD dilution
water, it is essential to
reoxygenate with a minimum
quantity of air because of the
contamination likely by contact
with dirty compressed or
laboratory air.
3 Oxygen solubility varies vvith the
temperature of the water.
Solubility at 10OC is about two
times that at 30oc. Temperature
often contributes to DO variations
much greater than anticipated by
32-2
-------
Dissolved Oxygen Determination (DO) - I
solubility. A cold water often has
much more DO than the solubility
limits at laboratory temperature.
Standing during warmup commonly
results in a loss of DO due to
oxygen diffusion from the super-
saturated sample. Samples
warmer than laboratory tempera-
ture may decrease in volume due
to the contraction of liquid as
temperature is lowered. The full
bottle at higher temperature will
be partially full after shrinkage
with air entrance around the stopper
to replace the void. Oxygen in the
air may be transferred to raise the
sample DO. For example, a
volumetric flask filled to the 1000 ml
mark at 30°C will show a water
level about 1/2 inch below the mark
when the water temperature is
reduced to 20° C. BOD dilutions
should be adjusted to 20° C + or -
1 1/2° before filling and testing.
4 Water density varies with tem-
perature with maximum water
density at 4t>C. Colder or warmer
waters tend to promote stratification
of water that interferes with
distribution of DO because the
higher density waters tend to seek
the lower levels.
5 Oxygen diffusion in a water mass is
relatively slow, hence vertical and
lateral mixing are essential to
maintain relatively uniform oxygen
concentrations in a water mass.
6 Increasing salt concentration
decreases oxygen solubility
slightly but has a larger effect
upon density stratification in a
water mass.
7 The partial pressure of the oxygen
in the gas above the water interface
controls the oxygen solubility
limits in the water. For example,
the equilibrium concentration of
oxygen in water is about 9 mg DO/1
under one atmospheric pressure of
air, about 42 mg DO/liter in
contact with pure oxygen and 0 mg
DO/liter in contact with pure
nitrogen (@ 20° C).
B Biological or Bio-Chemical Factors
1 Aquatic life requires oxygen for
respiration to meet energy
requirements for growth, repro-
duction, and motion. The net
effect is to deplete oxygen resources
m the water at a rate controlled
by the type, activity, and mass of
living materials present, the
availability of food and favor -
ability of conditions.
2 Algae, autotrophic bacteria, plants
or other organisms capable of
photosynthesis may use light
energy to synthesize cell materials
from mineralized nutrients with
oxygen released in process.
a Photosynthesis occurs only
under the influence of adequate
light intensity.
b Respiration of alga is
continuous.
c The dominant effect m terms
of oxygen assets or
liabilities of alga depends upon
algal activity, numbers and
light intensity. Gross algal
productivity contributes to
significant diurnal DO
variations.
3 High rate deoxygenation commonly
accompanies assimilation of
readily available nutrients and
conversion into cell mass or
storage products. Deoxygenation
due to cell mass respiration
commonly occurs at some lower
rate dependent upon the nature of
the organisms present, the stage
of decomposition and the degree
of predation, lysis, mixing and
regrowth. Relatively high
32-3
-------
Dissolved Oxygen Determination (DO) - I
deoxygenation rates commonly are
associated with significant growth
or regrowth of organisms.
Micro-organisms tend to flocculate
or agglomerate to form settleable
masses particularly at limiting
nutrient levels (after available
nutrients have been assimilated or
the number of organisms are large
in proportion to available food).
a Resulting benthic deposits
continue to respire as bed
loads.
b Oxygen availability is limited
because the deposit is physically
removed from the source of
surface oxygenation and algal
activity usually is more
favorable near the surface.
Stratification is likely to limit
oxygen transfer to the bed load
vicinity.
c The bed load commonly is
oxygen deficient and decomposes
by anaerobic action.
d Anaerobic action commonly is
characterized by a dominant
hydrolytic or solubilizing action
with relatively low rate growth
of organisms.
e The net effect is to produce low
molecular weight products
from cell mass with a corre-
spondingly large fraction of
feedback of nutrients to the
overlaying waters. These
lysis products have the effect
of a high rate or immediate
oxygen demand upon mixture
with oxygen contaming waters.
f Turbulence favoring mixing of
surface waters and benthic
sediments commonly are
associated with extremely
rapid depletion of DO.
Recurrent resuspension of
thin benthic deposits may
contribute to highly erratic 3
DO patterns.
g Long term deposition areas
commonly act like point
sources of new pollution as
a result of the feedback of
nutrients from the deposit.
Rate of reaction may be low
for old materials but a low
percentage of a large mass of
unstable material may produce
excessive oxygen demands.
Tremendous DO variations are likely
in a polluted water in reference to
depth, cross section or time of day.
More stabilized waters tend to show
decreased DO variations although it is
likely that natural deposits such as leaf
mold will produce differences related
to depth m stratified deep waters.
Ill ANALYTICA L METHOD BACKGROUND
The basic Winkler procedure (1888) has been
modified many times to improve its work-
ability in polluted waters. None of these
modifications have been completely
successful. The most useful modification
was proposed by Alsterberg and consists of
the addition of sodium azide to control
nitrite interference during the lodometric
titration. The Azide modification of the
lodometric titration is recommended as
official by the FWPCA Quality Control
Committee for relatively clean waters.
A Reactions
1 The determination of DO involves
a complex series of interactions
that must be quantitative to provide
a valid DO result. The number of
sequential reactions also compli-
cates interference control. The
reactions will be presented first
followed by discussion of the
functional aspects.
32-4
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Dissolved Oxygen Determination (DO) - I
MnSO + 2 KOH -Mn(OH)n + K„SO (a)
4 2 2 4
2 Mn(OH)2 + Oz —2 MnO(OH>2 (b)
MnO(OH)2 + 2 H2S04^ Mn(S04)2 + 3H20 (c)
Mn(S04)2 + 2 KI — MnS04 + K2S04 + I2 (d)
Na2S406 + 2NaI (.)
2 Reaction sequence
The series of reactions involves
five different operational steps in
converting dissolved oxygen in the
water into a form in which it can
be measured.
a 02—MnO(OH)2— Mn(S04)2 —
Ig-» Thiosulfate (thio) or
phenylarsine oxide (PAO)
titration.
b All added reagents are in excess
to improve contact possibilities
and to force the reaction toward
completion.
3 The first conversion, O —*¦
MnO(OH>2 (reactions a, d) is an
oxygen transfer operation where
the dissolved oxygen in the water
combines with manganous
hydroxide to form an oxygenated
manganic hydroxide.
a The manganous salt can react
with oxygen only in a highly
alkaline media.
b The manganous salt and alkali
must be added separately with
addition below the surface of
the sample to minimize reaction
with atmospheric oxygen via
air bubbles or surface contact.
Reaction with sample dissolved
oxygen is intended to occur
upon mixing of the reagents and
sample after stoppering the
full bottle (care should be used
to allow entrained air bubbles
to rise to the surface before
adding reagents to prevent
high results due to including
entrained oxygen).
c Transfer of oxygen from the
dissolved state to the pre-
cipitate form involves a two
phase system of solution and
precipitate requiring effective
mixing for quantitative
transfer. Normally a gross
excess of reagents are used
to limit mixing requirements.
Mixing by rapid inversion 25
to 35 times will accomplish
the purpose. Less energy is
required by inversion 5 or 6
times, allowing the solids to
settle half way and repeat the
process. Reaction is rapid,
contact is the principal
problem in the two phase
system.
d If the alkaline floe is white,
no oxygen is present.
Acidification (reactions c and d)
changes the oxygenated manganic
hydroxide to manganic sulfate
which in turn reacts with
potassium iodide to form elemental
iodine. Under acid conditions,
oxygen cannot react directly with
the excess manganous sulfate
remaining in solution.
Iodine (reaction e) may be titrated
with sodium thiosulfate standard
solution to indicate the amount of
dissolved oxygen originally
present in the sample.
a The blue color of the starch-
iodine complex commonly is
used as an indicator. This
blue color disappears when
elemental iodine has been
reacted with an equivalent
amount of thiosulfate.
32-5
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Dissolved Oxygen Determination (DO) - I
b Phenylarsine oxide solutions are
more expensive to obtain but
have better keeping qualities
than thiosulfate solutions.
Occasional use, field operations
and situations where it is not
feasible to calibrate thio
solutions regularly, usually
encourage use of purchased
PAO reagents.
6 For practical purposes the DO
determination scheme involves the
following operations.
a Fill a 300 ml bottle ; under
conditions minimizing DO
changes. This means that the
sample bottle must be flushed
with test solution to displace
the air in the bottle with water
characteristic of the tested
sample
^DO test bottle volumes should
be checked - discard those
outside of the limits of 300 ml
+ or - 3 ml.
b To the filled bottle
1) Add MnSO^ reagent (2 ml)
2) Add KOH, KI, NaN„ reagent
(2 ml) S
Stopper, mix by inversion,
allow to settle half way and
repeat the operation.
Highly saline test waters
commonly settle very
slowly at this stage and
may not settle to the half
way point in the time
allotted.
c To the alkaline mix (settled
about hall way) add 2 ml of
sulfuric acid, sloppet and mix.
d Transfer the contents of the
bottle to a 500 ml Erlenmeyer
flask and titrate with 0.0375
Normal Thiosulfate ¦ . Each
ml of reagent used represents
1 mg of DO/litei of sample.
The same thing applies for
other sample volumes when
using an appropriate titrant
normality such as-
1) For a 200 ml sample, use
0. 025 N Thio
2) For a 100 ml sample, use
0. 0125 N Thio
*FWPCA Official Method
7 The addition of the first two DO
reagents, (MnS04 and the KOH, KI
and NaNg solutions) displaces an
equal quantity of the sample. This
is not the case when acid is added
because the clear liquid above the
floe does not contain dissolved
oxygen as all of it should be con-
verted to the particulate MnOfOH^.
Some error is introduced by this
displacement of sample during
dosage of the first two reagents.
The error upon addition of 2 ml of
each reagent to a 300 ml sample
is X 100 or 1. 33% loss in DO.
300
This may be corrected by an
appropriate factor or by adjust-
ment of reagent normality. It is
generally considered small in
relation to other errors in sampling,
manipulation and interference,
hence this error may be recognized
but not corrected.
8 Precise directions are given in the
Official procedure attached to this
outline.
IV The sequential reactions for the
Chemical DO determination provides
several situations where significant inter-
ference may occur in application on
polluted water, such as
A Sampling errors may not be strictly
designated as interference but have the
same effect of changing sample DO.
Inadequate flushing of the bottle con-
tents or exposure to air may raise the
DO of low oxygen samples or lower the
DO of supersaturated samples.
32-6
-------
Dissolved Oxygen Determination (DO) - I
B Entrained air may be trapped in a DO
bottle by
1 Rapid filling of vigorously mixed
samples without allowing the
entrained air to escape before
closing the bottle and adding DO
reagents.
2 Filling a bottle with low temperature
water holding more DO than that in
equilibrium after the samples warm
to working temperature.
3 Aeration is likely to cool the sample
permitting more DO to be introduced
than can be held at the room or
incubator temperatures.
4 Samples warmer than working
incubator temperatures will be
only partially full at equilibrium
temperatures.
Addition of IX) reagents results in
reaction with dissolved or entrained
oxygen. Results for DO are invalid
if there is any evidence of gas
bubbles in the sample bottle.
C The DO reagents respond to any oxidant
or reductant in the sample capable of
reacting within the time allotted. HOC1
of H2O2 may raise the,DO titration
while HgS, 4 SH may react with sample
oxygen to lower the sample titration.
The items mentioned react rapidly and
raise or lower the DO r^ult promptly.
Other items such as Fe or SO, may
or may not react completely within the
time allotted for reaction. Many
organic materials or complexes from
benthic deposits may have an effect upon
DO results that are difficult to predict.
They may have one effect during the
alkaline stage to release iodine from
K1 while favoring irreversible
absorption of iodine during the acid
stage. Degree of effect may increase
with reaction time. It is generally
inadvisable to use the lodometric
titration on samples containing large
amounts of organic contaminants or
benthic residues. It would be expected
that benthic residues would tend toward
low results because of the reduced iron
and sulfur content - they commonly
favor high results due to other factors
that react more rapidly, often giving
the same effect as in uncontrolled
nitrite interference during titration.
D Nitrite is present to some extent m
natural waters or partially oxidized
treatment plant samples. Nitrite is
associated with a cyclic reaction during
the acid stage of the DO determination
that may lead to erroneous high results.
1 These reactions may be rep-
resented as follows-
2HN02 + 2 HI -J2 + 4H20 + N^ (a)
2HN02 ¦*"" + l/202+ H20 + N202 (b)
These reactions are time, mixing
and concentration dependent and
can be minimized by rapid
processing.
2 Sodium azide (NaN^) reacts with
nitrite under acid conditions to
form a combination of Ng + NgO
which effectively blocks the
cyclic reaction by converting the
HNO? to noninterfering compounds
of nitrogen.
3 Sodium azide added to fresh
alkaline KI reagent is adequate to
control interference up to about
20 mg of HNOg - N/liter of sample.
The azide is unstable and grad-
ually decomposes. If resuspended
benthic sediments are not detectable
in a sample showing a returning
blue color, it is likely that the
azide has decomposed in the
alkaline KI azide reagent.
E Surfactants, color and Fe+++ may
confuse endpoint detection if present
in significant quantities.
32-7
-------
Dissolved Oxygen Determination (DO) - I
F Polluted water commonly pontains
significant interferences such as C.
It is advisable to use a membrane
protected sensor of the electronic type
for DO determinations in the presence
of these types of interference.
A CKNOW LEDGMENTS
This outline contains significant materials
from previous outlines by J. W. Mandia.
Review and comments by C. R. Hirth and
R. L. Booth are greatly appreciated.
G The order of reagent addition and prompt
completion of the DO determination is
critical. Stable waters may give valid
DO results after extended delay of
titration during the acidified stage. For
unstable water, undue delay at any stage This outline was prepared by F. J. Ludzack,
of processing accentuates interference Chemist, National Training Center, FWPCA,
problems. Cincinnati, OH 45226.
32-8
-------
DISSOLVED OXYGEN DETERMINATION - II
ELECTRONIC MEASUREMENTS
I INTRODUCTION
A Electronic measurement of DO is attractive
for several reasons'
1 Electronic methods are more readily
adaptable for automated analysis, con-
tinuous recording, remote sensing or
portability
2 Application of electronic methods with
membrane protection of sensors affords
a high degree of interference control
3 Versatility of the electronic system
permits design for a particular measure-
ment, situation or use.
4 Many more determinations per man-
hour are possible with a minor expend-
iture of time for calibration
B Electronic methods of analysis impose
certain restrictions upon the analyst to
insure that the response does, in fact,
indicate the item sought.
1 The ease of reading the indicator tends
to produce a false sense of security.
Frequent and careful calibrations are
essential to establish workability of the
apparatus and validity of its response.
2 The use of electronic devices requires
a greater degree of competence on the
part of the analyst Understanding of
the behavior of oxygen must be supple-
mented by an understanding of the
particular instrument and its behavior
during use
C Definitions
1 Electrochemistry - a branch of chemistry
dealing with relationships between
electrical and chemical changes.
2 Electronic measurements or electro-
metric procedures - procedures using
the measurement of potential differences
as an indicator of reactions taking
place at an electrode or plate
3 Reduction - any process in which one
or more electrons are added to an atom
or an ion, such as O^ + 2e -* 20 1
The oxygen has been reduced
4 Oxidation - any process in which one
or more electrons are removed from
an atom or an ion, such as Zno - 2e
+9
—»• Zn . The zinc has been oxidized
5 Oxidation - reduction reactions - in a
strictly chemical reaction, reduction
cannot occur unless an equivalent
amount of some oxidizable substance
has been oxidized For example
2H2+°2 71 2H2°
2Hg - 4e 4H hydrogen oxidized
| _2
O^ + 4e *— 2 0 oxygen reduced
Chemical reduction of oxygen may also
be accomplished by electrons supplied
to a noble metal electrode by a battery
or other energizer.
6 Anode - an electrode at which oxidation
of some reactable substance occurs.
7 Cathode - an electrode at which
reduction of some reactable substance
occurs For example in I. C. 3, the
reduction of oxygen occurs at the
cathode.
8 Electrochemical reaction - a reaction
involving simultaneous conversion of
chemical energy into electrical energy
or the reverse. These conversions are
CH. O.do.32a.11.69
33-1
-------
Dissolved Oxygen Determination - II
equivalent rn terms of chemical and
electrical energy and generally are
reversible
9 Electrolyte a solution, gel, or mixture
capable of conducting electrical energy
and serving as a reacting media for
chemical changes. The electrolyte
commonly contains an appropriate
concentration of selected mobile ions
to promote the desired reactions
10 Electrochemical cell - a device con-
sisting of an electrolyte in which 2
electrodes are immersed and connected
via an external metallic conductor
The electrodes may be in separate
compartments connected by tube con-
taining electrolyte to complete the
internal circuit
a Galvanic (or voltaic) cell - an
electrochemical cell operated in
such a way as to produce electrical
energy from a chemical change,
such as a battery (See Figure 1).
b Polarographic (electrolytic) cell -
an electrochemical cell operated in
such a way as to produce a chemical
change from electrical energy
(See Figure 2).
MX)* |i[=i
Anode
Cathode
POLAROGRAPHIC CELL
Figure 2
Anode
Cathode
++
GALVANIC CELL
Fitart I
D As indicated in I. C 10 the sign of an
electrode may change as a result of the
operating mode. The conversion by the
reactant of primary interest at a given
electrode therefore designates terminology
for that electrode and operating mode
In electronic oxygen analyzers, the
electrode at which oxygen reduction occurs
is designated the cathode
E Each cell type has characteristic advantages
and limitations Both may be used
effectively.
1 The galvanic cell depends upon
measurement of electrical energy
produced as a result of oxygen
33-2
-------
Dissolved Oxygen Determination - II
reduction. If the oxygen content of the
sample is negligible, the measured
current is very low and indicator driving
force is negligible, therefore response
time is longer
2 The polarographic cell uses a standing
current to provide energy for oxygen
reduction. The indicator response
depends upon a change in the standing
current as a result of electrons
released during oxygen reduction.
Indicator response time therefore is
not dependent upon oxygen concentration.
3 Choice may depend upon availability,
habit, accessories, or the situation.
In each case it is necessary to use
care and judgment both in selection
and use for the objectives desired.
H ELECTRONIC MEASUREMENT OF DO
A Reduction of oxygen takes place in two
steps as shown 111 the following equations
1 02 + 2H20 + 2e — H202 + 20H~
2 H202 + 2e~ — 20H~
Both equations require electron input to
activate reduction of oxygen. The first
reaction is more important for electronic
DO measurement because it occurs at a
potential (voltage) which is below that
required to activate reduction of most
interfering components (0 3 to 0.8 volts
relative to the saturated calomel electrode -
SCE) Interferences that may be reduced
at or below that required for oxygen
usually are present at lower concentrations
in water or may be minimized by the use
of a selective membrane or other means.
When reduction occurs, a definite quantity
of electrical energy is produced that is
proportional to the quantity of reductant
entering the reaction. Resulting current
measurements thus are more specific for
oxygen reduction.
B Most electronic measurements of oxygen
are based upon one of two techniques for
evaluating oxygen reduction in line with
equation II A 1. Both require activating
energy, both produce a current propor-
tional to the quantity of reacting reductant
The techniques differ m the means of
supplying the activating potential, one
employs a source of outside energy, the
other uses spontaneous energy produced
by the electrode pair.
1 The polarographic oxygen sensor
relies upon an outside source of
potential to activate oxygen reduction
Electron gain by oxygen changes the
reference voltage
a Traditionally, the dropping mercury
electrode (DME) has been used for
polarographic measurements. Good
results have been obtained for DO
using the DME but the difficulty of
maintaining a constant mercury drop
rate, temperature control, and
freedom from turbulence makes it
impractical for field use.
b Solid electrodes are attractive
because greater surface area
improves sensitivity Poisoning
of the solid surface electrodes is
a recurrent problem The use of
selective membranes over noble
metal electrodes has minimized
but not eliminated electrode con-
tamination Feasibility has been
improved sufficiently to make thib
type popular for regular use.
2 Galvanic oxygen electrodes consist of
a decomposable anode and a noble
metal cathode in a suitable electrolyte
to produce activating energy for oxygen
reduction (an air cell or battery) Lead
is commonly used as the anode because
its decomposition potential favors
spontaneous reduction of oxygen The
process is continuous as long as lead
and oxygen are in contact in the electrolyte
and the electrical energy released at
the cathode may be dissipated by an
outside circuit The anode may be
conserved by limiting oxygen availability
Interrupting the outside circuit may
produce erratic behavior for a time
after reconnection. The resulting
33-3
-------
Dissolved Oxygen Determination - II
current produced by oxygen reduction
may be converted to oxygen concen-
tration by use of a sensitivity coefficient
obtained during calibration. Provision
of a pulsed or interrupted signal makes
it possible to amplify or control the
signal and adjust it for direct reading
in terms of oxygen concentration or to
compensate for temperature effects.
IE ELECTRONIC DO ANALYZER
APPLICATION FACTORS
A Polarographic or galvanic DO instruments
operate as a result of oxygen partial
pressure at the sensor surface to produce
a signal characteristic of oxygen reduced
at the cathode of some electrode pair
This signal is conveyed to an indicating
device with or without modification for
sensitivity and temperature or other
influences depending upon the instrument
capabilities and intended use
1 Many approaches and refinements have
been used to improve workability,
applicability, validity, stability and
control of variables. Developments
are continuing. It is possible to produce
a device capable of meeting any reasonable
situation, but situations differ
2 Most commercial DO instruments are
designed for use under specified con-
ditions. Some are more versatile than
others. Benefits are commonly reflected
in the price. It is essential to deter-
mine the requirements of the measure-
ment situation and objectives for use.
Evaluation of a given instrument in
terms of sensitivity, response time,
portability, stability, service
characteristics, degree of automation,
and consistency are used for judgment
on a cost/benefit basis to select the
most acceptable unit
B Variables Affecting Electronic DO
Measurement
1 Temperature affects the solubility of
oxygen, the magnitude of the resulting
signal and the permeability of the
protective membrane. A curve of
oxygen solubility m water versus
increasing temperature may be concave
downward while a similar curve of
sensor response versus temperature
is concave upward Increasing
temperature decreases oxygen solubility
and increases probe sensitivity and
membrane permeability Thermistor
actuated compensation of probe
response based upon a linear relation-
ship or average of oxygen solubility
and electrode sensitivity is not precisely
correct as the maximum spread in
curvature occurs at about 17° C with
lower deviations from linearity above
or below that temperature. If the
instrument is calibrated at a temperature
within + or - 5° C of working temperature,
the compensated readout is likely to be
within 2% of the real value. Depending
upon probe geometry, the laboratory
sensor may require 4 to 6% correction
of signal per ° C change in liquid
temperature
2 Increasing pressure tends to increase
electrode response by compression
and contact effects upon the electrolyte,
dissolved gases and electrode surfaces
As long as entrained gases are not
contained in the electrolyte or under
the membrane, these effects are
negligible.
Inclusion of entrained gases results in
erratic response that increases with
depth of immersion.
3 Electrode sensitivity changes occur as
a result of the nature and concentration
of contaminants at the electrode sur-
faces and possible physical chemical or
electronic side reactions produced.
These may take the form of a physical
barrier, internal short, high residual
current, or chemical changes in the
metal surface. The membrane is
intended to allow dissolved gas pene-
tration but to exclude passage of ions
or particulates Apparently some ions
or materials producing extraneous ions
within the electrode vicinity are able
to pass in limited amounts which
33-4
-------
Dissolved Oxygen Determination - II
become significant in time. Dissolved
gases include 1) oxygen, 2) nitrogen,
3) carbon dioxide, 4) hydrogen sulfide,
arid certain others. Item 4 is likely to
be a major problem. Item 3 may pro-
duce deposits in alkaline media, most
electrolytes are alkaline or tend to
become so in line with reaction n A. 1.
The usable life of the sensor varies
with the type of electrode system,
surface area, amount of electrolyte
and type, membrane characteristics,
nature of the samples to which the
system is exposed and the length of
exposure. For example, galvanic
electrodes used in activated sludge
units showed that the time between
cleanup was 4 to 6 months for electrodes
used for intermittent daily checks of
effluent DO, continuous use in the mixed
liquor required electrode cleanup in 2
to 4 weeks. Each electrometric cell
configuration and operating mode has
its own response characteristics.
Some are more stable than others.
It is necessary to check calibration
frequency required under conditions
of use as none of them will maintain
uniform response indefinitely. Cali-
bration before and after daily use is
advisable.
4 Electrolytes may consist of solutions
or gels of ionizable materials such as
acids, alkalies or salts. Bicarbonates,
KC1 and KI are frequently used. The
electrolyte is the transfer and reaction
media, hence, it necessarily becomes
contaminated before damage to the
electrode surface may occur. Electro-
lyte concentration, nature, amount and
quality affect response time, sensitivity,
stability, and specificity of the sensor
system. Generally a small quantity of
electrolyte gives a shorter response
time and higher sensitivity but also may
be affected to a greater extent by a
given quantity of contaminating sub-
stances.
5 Membranes may consist of teflon,
polyethylene, rubber, and certain
other polymeric films. Thickness
may vary from 0. 5 to 3 mils (inches X
1/1000). A thinner membrane will
decrease response time and increase
sensitivity but is less selective and
may be ruptured more easily. The
choice of material and its uniformity
affects response time, selectivity and
durability The area of the membrane
and its permeability are directly
related to the quantity of transported
materials that may produce a signal.
The permeability of the membrane
material is related to temperature and
to residues accummulated on the
membrane surface or interior. A
cloudy membrane usually indicates
deposition and more or less loss of
signal.
6 Test media characteristics control the
interval of usable life between cleaning
and rejuvenation for any type of
electrode More frequent cleanup is
essential in low quality waters than for
high quality waters. Reduced sulfur
compounds are among the more
troublesome contaminants. Salinity
affects the partial pressure of oxygen
at any given temperature. This effect
is small compared to most other
variables but is significant if salinity
changes by more than 500 mg/1.
7 Agitation of the sample in the vicinity
of the electrode is important because
DO is reduced at the cathode. Under
quiescent conditions a gradient in
dissolved oxygen content would be
established on the sample side of the
membrane as well as on the electrode
side, resulting in atypical response.
The sample should be agitated
sufficiently to deliver a representative
portion of the main body of the liquid
to the outer face of the membrane.
It is commonly observed that no
agitation will result in a very low or
negigible response after a short period
of time. Increasing agitation will cause
the response to rise gradually until
some minimum liquid velocity is reached
that will not cause a further increase
in response with increased mixing
energy. It is important to check
mixing velocity to reach a stable high
signal that is independent of a reasonable
change in sample mixing. Excessive
33-5
-------
Dissolved Oxygen Determination - n
mixing may create a vortex and expose
the sensing surface to air rather than
sample liquid. This should be avoided.
A linear liquid velocity of about 1 ft/sec
at the sensing surface is usually
adequate.
8 DO sensor response represents a
potential or current signal in the
milli-volt or milli-amp range in a
high resistance system. A high quality
electronic instrument is essential to
maintain a usable signal-to-noise ratio.
Some of the more common difficulties
include:
a Variable line voltage or low batteries
in amplifier power circuits.
b Substandard or unsteady amplifier
or resistor components.
c Undependable contacts or junctions
in the sensor, connecting cables, or
instrument control circuits.
d Inadequately shielded electronic
components.
e Excessive exposure to moisture,
fumes or chemicals m the wrong
places lead to stray currents,
internal shorts or other malfunction.
C Desirable Features in a Portable DO
Analyzer
1 The unit should include steady state
performance electronic and indicating
components in a convenient but sturdy
package that is small enough to carry.
2 There should be provisions for addition
of special accessories such as bottle
or field sensors, agitators, recorders,
line extensions, if needed for specific
requirements. Such additions should
be readily attachable and detachable
and maintain good working characteristics.
3 The instrument should include a
sensitivity adjustment which upon
calibration will provide for direct
reading in terms of mg of DO/liter.
4 Temperature compensation and temp-
erature readout should be incorporated.
5 Plug in contacts should be positive,
sturdy, readily cleanable and situated
to minimize contamination. Water
seals should be provided where
necessary.
6 The sensor should be suitably designed
for the purpose intended in terms of
sensitivity, response, stability, and
protection during use. It should be
easy to clean, and reassemble for use
with a minimum loss of service time.
7 Switches, connecting plugs, and con-
tacts preferably should be located on
or in the instrument box rather than
at the "wet" end of the line near the
sensor Connecting cables should be
multiple strand to minimize separate
lines Calibration controls should be
convenient but designed so that it is
not likely that they will be inadvertently
shifted during use.
8 Agitator accessories for bottle use
impose special problems because they
should be small, self contained, and
readily detachable but sturdy enough
to give positive agitation and electrical
continuity in a wet zone.
9 Major load batteries should be
rechargeable or readily replaceable.
Line operation should be feasible
wherever possible.
10 Service and replacement parts avail-
ability are a primary consideration.
Drawings, parts identification and
trouble shooting memos should be
incorporated with applicable operating
instructions in the instrument manual
in an informative organized form
D Sensor and Instrument Calibration
The instrument box is likely to have some
form of check to verify electronics,
battery or other power supply conditions
for use. The sensor commonly is not
included in this check. A known reference
33-6
-------
Dissolved Oxygen Determination - II
sample used with the instrument in an
operating mode is the best available
method to compensate for sensor variables
under use conditions. It is advisable to
calibrate before and after daily use under
test conditions. Severe conditions,changes
in conditions, or possible damage call for
calibrations during the use period. The
readout scale is likely to be labeled -
calibration is the basis for this label.
The following procedure is recommended
1 Turn the instrument on and allow it to
reach a stable condition. Perform the
recommended mstrument check as
outlined in the operating manual.
2 The instrument check usually includes
an electronic zero correction. Check
each instrument against the readout
scale with the sensor immersed in an
agitated solution of sodium sulfite
containing sufficient cobalt chloride to
catalyze the reaction of sulfite and
oxygen. The indicator should stabilize
on the zero reading. If it does not, it
may be the result of residual or stray
currents, internal shorting in the
electrode, or membrane rupture.
Minor adjustments may be made using
the indicator rather than the electronic
controls. Serious imbalance requires
electrode reconditioning if the electronic
check is O.K. Sulfite must be carefully
rinsed from the sensor until the readout
stabilizes to prevent carry over to the
next sample
3 Fill two DO bottles with replicate
samples of clarified water similar to
that to be tested. This water should
not contain significant test interferences.
4 Determine the DO in one by the azide
modification of the lodometric titration.
5 Insert a magnetic stirrer in the other
bottle or use a probe agitator. Start
agitation after insertion of the sensor
assembly and note the point of
stabilization.
a Adjust the instrument calibration
control if necessary to compare
with the titrated DO.
b If sensitivity adjustment is not
possible, note the instrument
stabilization point and designate
it as ua. A sensitivity coefficient,
llcL
is equal to where DO is the
titrated value for the sample on
which ua was obtained. An unknown
UcL
DO then becomes DO = ——
This
factor is applicable as long as the
sensitivity does not change.
Objectives of the test program and the
type of instrument influence calibration
requirements. Precise work may
require calibration at 3 points in the
DO range of interest instead of at zero
and high range DO. One calibration
point frequently may be adequate
Calibration of a DO sensor in air is a
quick test for possible changes in
sensor response The difference in
oxygen content of air and of water is
too large for air calibration to be
satisfactory for precise calibration
for use in water.
IV This section reviews characteristics of
several sample laboratory instruments
Mention of a specific instrument does not
imply FWPCA endorsement or recommendation.
No attempt has been made to include all the
available instruments, those described are
used to indicate the approach used at one
stage of development which may or may not
represent the current available model.
A The electrode described by Carrit and
Kanwisher (1) is illustrated in Figure 3.
This electrode was an early example of
those using a membrane. The anode was
a silver - silver oxide reference cell with
a platinum disc cathode (1-3 cm diameter).
The salt bridge consisted of N/2 KC1 and
33-7
-------
Dissolved Oxygen Determination - n
KOH. The polyethylene membrane was
held in place by a retaining ring. An
applied current was used in a polarographic
mode. Temperature effects were relatively
large. Thermistor correction was studied
but not integrated with early models.
Retaining Ring
PolyetKylen« Film
Silver Ring
Platinum Disk
Electrolyte Layer
Figure 3
B The Beckman oxygen electrode is another
illustration of a polarographic DO sensor
(Figure 4). It consists of a gold cathode,
a silver anode, an electrolytic gel con-
taining KC1, covered by a teflon membrane.
The instrument has a temperature readout
and compensating thermistor, a source
polarizing current, amplifier with signal
adjustment and a readout DO scale with
recorder contacts.
SENSOR
Figure 4, THE BECKMAN OXYGEN
SENSOR
C The YSI Model 51 (3) is illustrated in
Figure 5. This is another form of
polarographic DO analyzer. The cell
consists of a silver anode coil, a gold
ring cathode and a KC1 electrolyte with
a teflon membrane. The instrument has
a sensitivity adjustment, temperature and
DO readout. The model 51 A has temp-
erature compensation via manual preset
dial. A field probe and bottle probe are
available.
YSI Model 51 DO Sensor
Membrane
KCL Solution
Anode Coil
Cathode Ring
Figure 5
D The Model 54 YSI DO analyzer (4) is based
upon the same electrode configuration but
modified to include automatic temperature
compensation, DO readout, and recorder
jacks, A motorized agitator bottle probe
is available for the Model 54 (Figure 6).
Agitator Motor
Agitator Drl
33-8
-------
Dissolved Oxygen Determination - II
E The Galvanic Cell Oxygen Analyzer (7, 8)
employs an indicator for proportional DO
signal but does not include thermistor
compensation or signal adjustment.
Temperature readout is provided. The
sensor includes a lead anode ring, and
a silver cathode with KOH electrolyte
(4 molar) covered by a membrane film
(Figure 7).
Precision Galvanic Cell Oxygen Probe
Thermistor Cable
' Retainer
Tapered Section
lo Fit BOD Bottles
Plastic Membrane
Retainer Ring
Silver Cathode
Lead Anode Ring
Polyethylene Membrane
Figure 7
F The Weston and Stack Model 300 DO
Analyzer (8) has a galvanic type sensor
with a pulsed current amplifier adjustment
to provide for signal and temperature
compensation. DO and temperature
readout is provided. The main power
supply is a rechargeable battery. The
sensor (Figure 8) consists of a lead anode
coil recessed in the electrolyte cavity
(50% KI) with a platinum cathode in the tip.
The sensor is covered with a teflon mem-
brane. Membrane retention by rubber
band or by a plastic retention ring may be
used for the bottle agitator or depth
sampler respectively. The thermistor
and agitator are mounted in a sleeve that
also provides protection for the membrane.
G The EIL Model 15 A sensor is illustrated
in Figure 9. This is a galvanic cell with
thermistor activated temperature com-
pansation and readout. Signal adjustment
is provided. The illustration shows an
expanded scheme of the electrode which
when assembled compresses into a sensor
approximating 5/8 inch diameter and 4 inch
length exclusive of the enlargement at the
upper end. The anode consists of com-
pressed lead shot in a replaceable capsule
(later models used fine lead wire coils),
a perforated silver cathode sleeve around
the lead is covered by a membrane film.
The electrolyte is saturated potassium
bicarbonate. The large area of lead
surface, silver and membrane provides
a current response of 200 to 300 micro-
amperes in oxygen saturated water at
20°C for periods of up to 100 days use (8).
The larger electrode displacement favors
a scheme described by Eden (9) for
successive DO readings for BOD purposes.
*
V Table 1 summarizes major characteristics
of the sample DO analyzers described in
Section IV. It must be noted that an ingenious
analyst may adapt any one of these for special
purposes on a do-it-yourself program. The
sample instruments are mainly designed for
laboratory or portable field use. Those
designed for field monitoring purposes may
mclude similar designs or alternate designs
generally employing larger anode, cathode,
and electrolyte capacity to approach better
response stability with some sacrifice in
response time and sensitivity. The electronic
controls, recording, telemetering, and
accessory apparatus generally are semi-
permanent installations of a complex nature.
ACKNOWLEDGMENTS
This outline contains certain materials from
previous outlines by D. G. Ballinger,
N.C. Malof, and J.W. Mandia. Additional
information was provided by C.R. Hirth,
C.N. Shadix, D.F. Krawczyk, J. Woods,
and others.
33-9
-------
Dissolved Oxygen Determination - II
WESTON & STACK
DO PROBE
0— CORD
(5 ) CORD RESTRAINER
SERVICE CAP
©- PROBE SERVICE CAP
ELECTROLYTE FILL SCREW
(6 ) PROBE BODY
(D— pla TINUM CATHODE
CONNECTOR PINS
(9) PIN HOUSING
(jO) LEAD ANODE
(TT) REMOVABLE PROBE SHIELD
AND THERMISTOR HOUSING
Figure 8
33-10
-------
Cable
Connection
Cover
A15016A
O' Ring
R524
ble Sealing
Nut
A 15017
'O' Ring
R389
Cable
'O' Ring
R385
Membrane— Securing
'O' Ring
R317
Lead Anode
Complete
(A15024A)
Membrane Securing
O' Ring
R317
Silver Cathode
A15013A
Anode
Contact
A-150140
(With Sleeve S24)
1
¦
¦ ¦IMIKIIIItl
Filler Sc
Z471
O' Ring
R612
O R ing
1622
Anode
Contact
Holder
A15015A
End Cap
A15011A
O' Ring
R622
Note: Red wire of cable connects to Anode Contact Holder
Black wire of cable connects to Anode Contact
Membrane not shown E I. L. part number T221
Figure 9
-------
TABLE 1
CHARACTERISTICS OF VARIOUS LABORATORY DO INSTRUMENTS
DO Temp.
Sig Comp Accessories for
Anode Cathode Elec Type Membr Adj Temp Rdg which designed
Carrit &
Kanwisher
silver-
silver ox.
ring
Pt
disc
KC1
KOH
N/2
pol
polyeth
no
no
Recording temp.
&. signal adj self
assembled
Beckman
Aq
ring
Au
disc
KCL
gel
pol
teflon
yes
yes
yes
recording
Yellow Springs
51
Ag
coil
Au
ring
KC1
soln
sat.
pol
teflon
yes
no
yes
field and bottle
probe
Yellow Springs
54
M
1!
II
yes
yes
yes
recording lield
bottle & agitator
probes
Precision
Sci
Pb
ring
silver
disc
KOH
4N
galv
polyeth
no
no
.yes
Weston &
Stack
300
Pb
coil
Pt
disc
KI
40%
galv
teflon
yes
yes
yes
a git probe
depth sampler
EIL
Pb
Ag
khco3
galv
teflon
yes
yes
yes
recording
Delta
75
Lead
Silver
disc
KOH
IN
galv
teflon
yes
yes
no
field bottle ^
agitator probe
Delta
85
Lead
Silver
disc
KOH
IN
galv
teflon
yes
yes
yes
field bottlr &
agitator probn
'¦Pol - Polarographic (or amperimetric)
Galv - Galvanic (or voltametric)
REFERENCES
1 Carrit, D E and Kanwisher, J.W.
Anal. Chem 31 5 1959
2 Beckman Instrument Company Bulletin
7015, A Dissolved Oxygen Primer,
Fullerton, CA 1962.
3 Instructions for the YSI Model 51 Oxygen
Meter, Yellow Springs Instrument
Company, Yellow Springs, OH 45387.
4 Instructions for the YSI Model 54 Oxygen
Meter, Yellow Springs Instrument
Company, Yellow Springs, OH 45387.
5 Technical Bulletin TS-68850 Piooisinn
Scientific Company, Chicago, IL fiH647
6 Mancy, K. H., Okun, D.A and Rcilley,
C N J Electroanal Chcm 4 fir>
1962
7 Instruction Bulletin, Weston and Stack
Model 300 Oxygen Analyzer Roy F
Weston, West Chester, PA 19380.
8 Briggs, R and Viney, M. Design and
Performance of Temperature Com-
pensated Electrodes for Oxygen
Measurements Jour, of Sci.
Instruments 41 78-83 1964.
33-12
-------
Dissolved Oxygen Determination - II
9 Eden, R.E. BOD Determinations Using
a Dissolved Oxygen Meter. Water
Pollution Control pp. 537-539. 1967.
10 Skoog, D A. and West, D.M. Fundamentals
of Analytical Chemistry. Holt,
Rinehart & Winston, Inc. 1966.
11 FWPCA Methods for Chemical Analysis of
Water and Wastes. FWPCA Div of
Water Quality Research Analytical
Quality Control Laboratory, Cincinnati,
OH. p. 65-68 November 1969
This outline was prepared by F. J. Ludzack,
Chemist, National Training Center, FWQA,
Cincinnati, OH 45226 and Nate Malof, Chemist,
National Field Investigations Center, FWQA,
Cincinnati, OH.
33-13
-------
BOD PROCEDURES FOR TREATMENT PLANT OPERATIONS
I INTRODUCTION
A The BOD procedure for treatment plant
operation is a compromise between what
is sought and what may be obtained. The
five-day incubation (or BOD,.) is one of the
compromises.
B Most treatment plants have been designed
on a BOD,, or BODg^ basis. The BOD,, is
the most common basis of evaluating
plant performance or discharges to surface
water. This outline and another on BOD
variables discusses the partial response
of the BOD,. test and means whereby the
test may be performed or applied more
realistically. A partial result is valid
if you know the fraction of total oxygen
demand represented by BOD,, compared
to total demand. Supplementary tests are
suggested which are useful for inter-
pretation of BODj. results. These tests
are useful to avoid many misleading
assumptions.
C The BODg test indicates the sum of various
chemical or biological oxidations expressed
• in terms of oxygen use under specified
conditions and time. The fraction included
in the five-day test may include:
1 Oxygen used for conversion of waste-
water substances into slime organisms
(living cells of bacteria, fungi, yeasts,
etc.) with partial oxidation in process.
This may be considered as first stage
or carbonaceous oxygen demand.
2 Slime growth tends to be associated
with organism death and decay. When
the original feed has been largely
converted to cells, remaining oxidation
occurs by regrowth on decay products
and the activity of slower growing
organisms such as nitrifiers. This
may be considered as second stage or
nitrogenous oxidation.
3 Certain chemicals may react with
oxygen relatively quickly. The
resulting use of dissolved oxygen that
is exerted within fifteen minutes is
considered immediate dissolved
oxygen demand (IDOD or sometimes
IOD). Examples of chemicals
associated with IDOD include but are
not limited to hydrogen sulfide,
mercaptans, sulfites, thiosulfates
(Thio) and some of the reduced
(ferrous) iron.
D There is no way to classify a BOD,, result
in terms of I.C. 1, 2 or 3 without
supplementary information or tests
1 Raw wastewaters, primary effluents,
or process waters may become septic
and show a significant fraction of B3
in the BODc result.
D
2 B. 1 is likely to be the main component
of oxygen use in a fresh wastewater as
a result of rapidly growing slime
organisms and readily available foods.
3 The BOD,, of partially treated samples,
secondary effluents or stabilized
surface waters may be partially or
almost completely the result of B.2.
4 Depending upon the past history of the
sample the BOD^ may be due to any
one, any combination or all three of
the stages listed in B. 1, 2 or 3.
Interpretation may be misleading if
you depend solely on BOD,..
5 The BOD^ test is a bottle test per-
formed under conditions different from
those m a plant or stream^). The
BOD test bottle commonly is not
agitated during incubation The test
incubation is likely to contain a small
fraction of the number and variety of
organisms per unit of food compared
CH. O.bod. 59. 8. 70
34-1
-------
BOD Procedures for Treatment Plant Operations
with that in a plant treatment unit
The test bottle commonly isn't reseeded
and time for adaptation is limited as
compared with plant conditions. The
plant oxygen use is likely to be more
rapid and more complete than that in
the bottle.
6 BOD testing presumes favorable ranges
for the essentials of biodegradation.
It is unlikely that all of the sample
components are known or that all re-
quired conditions are at their most
favorable level ^and remain so during
incubation. Any requirement for bio-
degradation that is too low or too high
for BOD development will produce a
BODg result that is lower than the
plant or stream oxygen demand.
E The BOD,, test cannot stand alone. Sample
history and background suggest that which
may have occurred. It is not advisable to
presume. The following tests help to
clarify the situation with respect to BOD,,
results and total load. These tests
become more important as treatment
requirements rise
1 The IDOD test is important whenever
the wastewater or process stream
shows no DO. It becomes more
important as the time without DO
increases, as the temperature rises
and with a rise in probability that the
mixture contains items such as those
in I. B. 3.
2 The total load is more important than
the BOD,, load estimate.
a The chemical oxygen demand (COD)
test result is a fair estimate of first
stage oxygen demand for most
municipal wastewaters.
b The total organic carbon (TOC) X2.67
is an excellent estimate of first stage
demand but is not likely to be available
at small plants.
c The second stage oxygen demand may
be estimated by determining ammonia
plus organic nitrogen (total Kjeldahl
nitrogen - TKN) and multiplying the
by a factor of 4.57 (the oxygen
equivalent of unoxidized nitrogen).
d The BOD,, result divided by an
estimate of total demand provides
an estimate of the fraction of oxygen
demand that was included in the
BOD,. compared to that which may
be needed for sample stabilization
under other conditions and extended
time. Two possible forms are-
BOD5 or
COD + (4. 57 XTKN)
BODc
D
(2. 67 XTOC) + (4. 57 XTKN)
all results expressed in mg/1.
For example- a series of tests
(in mg/1) on a river water included
BOD - 7 to 10, BOD - 25 to 35,
COD - 50 to 85, TKN - 15 to 25.
Taking the lower values in the range
and substituting gives
7 = 7 _ 7
50 + (4.57 X 15) 50 + 68 = 118
or the information that the BOD,,
of this river represented about
6 percent of the possible oxygen
demand in it This information
made it easier to explain a complete
oxygen deficiency in the river about
two miles below the cited sample
point.
e Total, suspended and volatile solids
(TS, SS and VS) are readily obtainable
and useful means to estimate what
has been or remains to be done.
The volatile solids (of TS or SS) are
directly relatable to oxygen demand.
Wastewater treatment is concerned
with a reduction in sample volatile
solids either by oxidation or take-out.
II BOD TEST EQUIPMENT (1, 2, 4)
A Standard Incubation Bottles
34-2
-------
BOD Procedures for Treatment Plant Operations
1 300 ml bottles with a water seal lip
are preferred. Reject for BOD use
any bottles containing less than 297
or more than 303 ml.
2 Carefully clean new or used bottles with
glass cleaning detergent and brushing.
Rinse each bottle with good quality dis-
tilled water, completely drain each
bottle after each rinse using an upside
down vertical position (4 to 10 rinses
depending upon soil and cleaning agent
used to remove it).
3 Do not use regular BOD bottles for
sample or reagent use.
4 Provide wire, chain, or other ties to
keep properly fitted stoppers and
bottles together.
5 It is helpful to provide paper cups such
as those used for coffee creamers in
restaurant use (size to fit the bottle top)
to decrease water seal evaporation
during incubation.
B Wood or wire rack to hold BOD bottles
upside down for drainage or storage.
Inclined pegboards are not satisfactory.
C Air or water bath incubator large enough
to avoid crowding during anticipated
bottle incubation.
1 Temperature thermostatically con-
trolled at 20° C + or - lo C in all parts
of the storage area. Air or water
mixing is advisable.
2 BOD incubations are intended to be in
darkness. Do not store reagents or
samples in incubator space. This will
encourage frequent door opening. Even
short light periods may encourage algal
activity in certain samples. This will
raise DO and confuse the anticipated
oxygen depletion.
D Titration assembly and accessories for the
azide modification of the lodometric DO.
E An electronic DO probe fitted for bottle use
is encouraged for routine use. After daily
calibration check the probe favors more
oxygen determinations in less time with
less serious interference problems than
by titration. It will be possible to deter-
mine DO where a valid result by titration
would be unlikely.
F Waring blender or other mixer to break
up clumps in samples to be subsampled
for BOD purposes.
G pH meter for adjustment and check of
samples, reagents and dilutions.
H Pipets, burets, thermometers, graduates,
containers adequate to facilitate operations
intended. Reference 4 is useful for
identification and handling.
in BOD REAGENTS (1, 2, 4)
A High quality water is required that does
not introduce more than trace amounts of
oxidizable materials or substances that
interfere with biological stabilization.
Copper and chlorine are common prob-
lems, many others are possible.
1 Block tin, stainless steel or glass
« stills are advisable. It may be
advisable to install an activated
carbon column in the line ahead of
the distilling unit to remove chlorine
and certain organics that would be
transferred to the product water.
Deionization units may be effective.
2 Satisfactory distilled water is indicated
if the BODj. for mineral fortified
distilled water seeded with about 1 to
5 drops/liter of well stabilized river
water is less than 0. 4 mg DO, also
that the same seeded water to which
2 percent of a solution of 0. 15 g
glucose and 0. 15 g glutamic acid/liter
has a depletion of at least 4. 0 mg DO.
B Mineral Supplements (Reference 1, page
416)
1 Phosphate buffer solution
2 Magnesium sulfate solution
3 Calcium chloride solution
34-3
-------
BOD Procedures for Treatment Plant Operations
4 Ferric chloride solution
Ammonium chloride may be omitted from
solution 1 if the samples contain more
than adequate nitrogen for growth. Most
municipal wastewaters are in this group.
These reagents should be replaced when-
ever growth, precipitation or contamination
is apparent or suspected.
C DO Reagents
D One normal acid and alkali solutions for
sample neutralization prior to BOD
incubation.
E Seeding material, if necessary.
1 Most samples in wastewater treatment
operations do not require seeding.
2 Seeding is indicated with samples that
have been heated, acid, alkali, or
chemically treated to kill the organisms
normally present.
3 The seed should contain a variety of
mixed organisms capable of starting
BOD exertion as soon as it is mixed
with sample oxidizable material. *
The seed should not contain significant
amounts of available food other than
organisms that would favor a high seed
BOD .
D
4 The best source of seed would be a well
stabilized receiving water. A well
stabilized secondary treatment plant
effluent would be an alternate choice.
The amount must be determined by
trial (usually less than one percent).
5 Seed corrections are questionable
because a seed does not oxidize in the
same manner in the presence of food
as it does without it. Different con-
centrations are unlikely to behave
similarly. Don't use seeding unless
absolutely necessary. Fresh or stale
sewage seeds are not recommended
because this material has not had time
to develop populations characteristic
of those in a treatment plant or stream.
IV BOD PROCEDURES (1, 2, 4)
A The Immediate Dissolved Oxygen Demand
(IDOD) test commonly is ignored in BOD-
results. It is included in the result if
you use a calculated initial DO. It is not
included if you use a determined initial DO.
As discussed previously any fraction of the
oxygen demand that occurs within fifteen
minutes of mixing is part of the IDOD.
It is likely to be associated with any
sample in which the DO has been
exhausted. It is advisable to test for it
because this demand is very rapidly
exerted and may seriously affect oxygen
supply and/or BOD^ results.
1 Determine the DO of the sample
(usually zero) and the dilution water
separately. Mix definite proportions
of the two. After fifteen minutes
determine the DO in the combination.
Calculate what the DO should have
been in the mixture. Any difference
between the calculated and determined
value is due to experimental error or
IDOD of the sample.
2 Example
a The sample contained no measurable
DO, dilution water contained 8.6 mg
DO/liter. Ten percent of the sample
was mixed with 90 percent dilution
water. After fifteen minutes the
mixture indicated 3. 2 mg DO/liter.
b Initial DO of the mixture (no IDOD)
should have been:
10 parts of 0 DO water = 0 oxygen units
90 parts of 8.6 DO
water = 774.0 oxygen units
(90 X 8.6)
100 parts of the mixture contains 774 oxygen
units
774
DO per part = Jqq = 7. 74 mg DO/liter
c Observed DO after fifteen minutes
= 32 mg DO/liter
34-4
-------
BOD Procedures for Treatment Plant Operations
Then IDOD = (ImtiaI DQcalc " POi5 mjn) x 100
% dilution
= (7.74 - 3.2)X100
10
= 4. 54 X 100 = 45 mg IDOD/liter
10
3 The IDOD would have to be satisfied
before DO for aerobic activity could
be supplied.
4 It is advisable to use a DO probe for
IDOD tests. Samples likely to show
negligible DO are likely to contain
serious interferences for DO titration
which are not serious when using a
membrane protected DO probe.
5 In BODg work, try a calculated and
determined initial in the calculation.
If the results for the two initials are
significantly different you have
problems -- IDOD, technique or
calculation.
B Undiluted sample BOD,, may be determined
on samples in which the BOD& is less than
about 8 mg/1. This limit may be extended
3 to 5 times if you reoxygenate the sample
during the five day incubation or oxygenate
the sample with oxygen gas instead of air.
Extending the range of undiluted sample
BOD technique is attractive for effluent
and stream analysis to avoid dilution and
dilution water problems but generally isn't
feasible for routine operation.
1 The undiluted sample procedure
includes
a Mix the sample vigorously by shaking
in a half filled bottle to insure that
the initial DO is in the range of 8. 0
to 8. 7 mg/liter.
b Siphon the mixture into two or more
BOD bottles being careful to avoid
inclusion of air in the sample bottle.
c Determine the DO on one bottle.
d Incubate at 2 0° C + or - 1°C for five
days and determine the DO final.
e mg BODc/liter = DO. ... , - DO.. .
b 5 initial final
X100
C Diluted Sample BOD_
5
1 Most BOD,, data on treatment plant
influents, in-process samples or
discharges employ dilution technique.
The sample is reduced to some fraction
in which the oxygenated dilution water
can supply more than enough oxygen to
meet sample requirements during
incubation. Dilution technique com-
plicates the procedure as a result of
dilution water addition but the methods
are similar to those for undiluted
samples.
2 Dilution technique is feasible on the
basis of:
a Single bottle dilution where the
measured sample amount is added
directly to each bottle and enough
dilution water siphoned into it to
fill but not overfill the bottle.
b Cylinder dilution technique employs
a container large enough to make one
dilution of sample and dilution water
to be used to fill all of the test
bottles needed. The contents are
siphoned into the separate bottles
with care not to change DO during
transfer.
3 Before dilutions are selected it is
necessary to make some estimate of
possible BOD range. Previous
experience, COD testing, or other
information may be used as a guideline
for dilution. In any event, several
dilutions are likely to be necessary to
obtain one within a usable range of DO
depletion. Best results are obtained
from a DO depletion of at least 2 mg/1
with at least 1 mg/1 remaining after
incubation. Standard Methods ^ ^
recommends 40 to 70 percent oxygen
depletion.
34-5
-------
BOD Procedures for Treatment Plant Operations
4 The interrelationship between BOD and
dilution for BOD^ are-
BOD:
5-
20-
20 mg/ liter
100 mg/liter
100- 500 mg/liter
500-5000 mg/liter
Dilution
use 25 to 100 percent sample
use 5 to 25 percent sample
use 1 to 5 percent sample
use 0. 1 to 1 percent sample
To calculate dilution from an assumed
BOD use the same formula for
calculation of BOD. That is-
(DOr
, DO )X100
BOD, (mg/1) = -
5 % sample used
If you assumed a BOD of 500 mg/1
the sample depletion in the middle
of the acceptable range would be
4. 0 to 5.0 mg/1 say 4. 5 to be used
in place of (DO - DO )
U j
Then 500
% sample =
4.5 X100
% sample
4.5 X100
500
or,
450
500
or 0. 9%
It would not be advisable to use the
calculated percent of sample only
because the sample may be weaker
or stronger than the assumed value.
It is preferable to make one smaller
and one larger dilution--say 0. 5,
1. 0 and 2 percent sample to cover
a possible range in BOD of-
0
mg BOD,_/liter for minimum depletion,
maximum concentration
Formula IV. C. 4. b. =
= 100 mg/1
2.0 X100
for maximum depletion, minimum
7.0 X100 _ 700
0.5 "0.5
concentration =
1400 mg/1
d Once you have decided upon an
acceptable dilution range
1) For direct bottle dilution,
multiply the decimal fraction
of the percentage desired by bottle
capacity to obtain sample amount
to be added to each bottle. For
a 300 ml bottle and 1 percent
sample concentration
300 X0.01 - 3 ml sample.
0. 5 and 2. 0 percent would be
1.5 and 6 ml respectively.
2) For cylinder dilution technique
you would have to fill at least
two bottles, one for initial one
for final DO titration, hence you
would need at least 600 ml of
dilution mix not counting that to
start, flush the siphon and over-
run. Better figure dilution volume
as 800 ml. Sample addition
would be 800 X 0. 01 for 1 percent
sample concentration or 8 ml to
be filled to the mark (800 ml) with
dilution water.
e After dilution to the mark, mix the
sample carefully. If you plan on a
calculated initial do not beat air
into the sample during mixing.
With a determined initial you may
oxygenate by mixing (inversion,
shaking, plunger action) allow
entrained air to rise before starting
the siphon.
f Fill the intended bottles by flushing
the siphon to be sure that you have
swept out air bubbles and previous
dilutions, tilt the BOD bottle slightly,
insert siphon tip to the lowest point
in the bottle, gradually open the
siphon tube to admit diluted sample
to fill the bottle. Stopper without
inclusion of air bubbles.
g Determine the initial DO one one
bottle, incubate the other for DO
determination after 5 days at 20OC
+ or - 1°C.
(DO - DO ) X 100
mg BOD /liter = —
5 % sample used
34-6
-------
BOD Procedures for Treatment Plant Operations
D Dilution Water Blanks
1 It is important that you regularly check
the quality of the dilution water to be
used for BOD dilutions. This water
should not contain excessive oxidizable
materials nor should it inhibit oxidation
of other materials.
2 Many analysts use undiluted BOD
technique determine initials and BOD,,
on unseeded dilution water. In this
case, air seeding is expected to provide
the necessary organisms. Others add
one drop or more of a well stabilized
receiving water to the dilution water
blank.
3 Many analysts use the DO^ of the dilution
water blank in place of the DO^ of the
dilution mix to correct for dilution
water depletion. Others use the blank
as a dilution water quality check, with
or without correction.
4 This author makes no recommendations
other than that in III. A. 2. It is necessary
for you to consult your local or State
authorities for recommended practice.
E Seeding, like dilution water, corrections
are questionable. A seed depletion deter-
mined on an undiluted high quality water
may be quite different from the decimal
fraction of that depletion in another water
and another sample.
V AUXILIARY BOD COMMENTS
A Many procedures are available for BOD
technique in addition to those considered
here. For example, Standard Methods and
this outline includes full bottle technique,
DO measurement, no agitation during
incubation. The Hach apparatus employs
partially filled bottles, with agitation and
a pressure measurement. These and
others may be used effectively if used
consistently, carefully, and the methods
are known by those who interpret them.
Many options are possible each having an
affect upon results. Stick to the preferred
method in your area. You may have a
better option but you have to prove it to
them before acceptance.
B Carefully identify samples, dates, time
on any test container. Note unusual
appearance, behavior, etc. Promptly
inform operations authority of observations
likely to affect performance. Keep your
records up to date and in consistent
legible form. Data is worthless unless
available when needed.
C The Azide Modification of the Winkler
titration has a long record in BOD
technique. A DO probe has many advantages
in BOD technique once the analyst knows
how to use it. It will require much less
time for determination of BOD, there is
no prepreparation of samples, the sample
is not destroyed and it requires fewer
bottles and space. The probe and Winkler
method have about the same degree of
precision on tap water samples. In plant
samples the probe may be used effectively
on many samples where titration is not
effective.
D Do not use large volumes of air by diffusor
technique to oxygenate dilution water.
You will tend to concentrate air impurities
in the clean water. You may filter dust
from the air; you are not likely to remove
chlorine, ammonia, organic gases and
possibly oils in the same manner. Con-
tamination may add BOD^ or interfere
with biological stabilization. Air at room
temperature contains more than 200 mg
of oxygen per liter. This is ample to
saturate several liters of water with DO.
Storage for two to three days without
agitation or mixing rapidly by inversion
or shaking for ten to thirty seconds will
transfer oxygen from the gas to the liquid
without undue water contamination.
E It is not advisable to use BOD initials
(DO_) higher than about 8. 7 mg/1. This
is about 95 percent of DO saturation at
20° C. If the temperature rises during
or after incubation some of the DO may
be lost because of super saturation to
confuse BOD results.
D
F BODg samples to be incubated should be
adjusted before filling bottles to a tem-
perature range from 18.5 to 21.5°C.
Warmer samples are particularly dangerous
as the liquid contracts on cooling. If the
34-7
-------
BOD Prodecures for Treatment Plant Operations
water seal isn't adequate, air will be
drawn into the bottle.
ACKNOWLEDGMENT:
This outline contains certain information
from previous outlines by D. G. Ballinger,
R.C. Kroner, and J.M. Mandia.
3 FWPCA (Now FWQA) Methods for ,
Chemical Analysis of Wat^r and
and Wastes, Analytical Quality Control
Laboratory. November 1969.
4 MOP 18 Simplified Laboratory Procedures
for Wastewater Examination. WPCF.
1968.
REFERENCES
1 Standard Methods for the Examination of
Water and Wastewater, APHA, AWWA,
WPCF, 12th Ed. p. 415. 1965.
2 ASTM Standards Part 23, Water and
Atmospheric Analysis, pp. 727-732.
1968.
This outline was prepared by F. J. Ludzack,
Chemist, National Training„Center,
Federal Water Quality Administration,
Cincinnati, OH 45226.
34-8
-------
EFFECT OF SOME VARIABLES ON THE BOD TEST
I TIME
-kt.
A The common equation yt = L (1 - 10 ) for
BOD relationship irdicates time as a
variable. The rate coefficient (kj)indicates
that a specific percentage of material
initially present (oxygen) will be used
during a given time unit. Each successive
unit of time has less reactant present
initially than the preceding interval, hence
a definite precentage decrease results in
successively smaller amounts of reactant
use per unit of lapsed time. Increasing
kj^ results in a larger percentage oxygen
use per unit of time and also increases the
change m reactant mass among successive
time intervals.
B Adney's work for the British Royal Com-
mission cited 5 days passage time from
source to the ocean as maximum for
English streams. The 8th Report (1909)
largely established BOD philosophy in-
cluding the 5-day interval. At 5 days,
initial lags generally have terminated and
a substantial fraction of the long-term
oxygen demand has been exerted. If only
one time interval can be used, 7 days
permits better scheduling. Any one time
interval is "a" fraction of the total oxygen
requirement, this is a poor reference
point if we do not know the rate of oxida-
tion For example, the percentage of
oxidizable material stabilized in terms
of oxygen use at various rate factors
are
% oxidized
k, (loglf1) in 5 .days K x (log )
0.1)5 42% 0.11
0.10 67% 0.23
0.15 84% 0.34
0. 25 94% 0.57
0. 50 99+% 1. 15
This range = 2. 3 k-^ is commonly en-
countered in wastewater stabilization with
the higher rates characteristic of fresh oxi-
dizable material that is readily converted.
The lower coefficients are characteristic
of cell mass at later stages of oxidation
and of low-rate reactants in general.
C The oxygen utilization at specified inter-
vals of time are required to estimate kj,
and L, the estimate of oxygen use at
infinite time. It is common to observe
results at equal intervals of time but
this is not essential as long as
the time intervals are accurately known.
The initial time periods are critical as
an error of a few hours in time represents
a relatively large change in reactant mass
in a system at maximum instability. Un-
equal time periods can be plotted to define
the curve from which any given intervals
can be selected as desired.
D Increasing impoundment of surface water
provides more time for stabilization of
relatively inert soluble or suspended
pollutants and for organism adaptation
to the situation or pollutants. Long term
BOD's are essential to indicate changes
in the pattern of oxygen demand vs. time.
It may be expected that one or more
plateaus will be evident in the BOD curve
followed by a temporary rise in rate
during second stage oxidation or thereafter.
Anaerobiosis may cause a rise in rate
coefficient after aerobic conditions are
re-established. Eventually k^ stabilizes
at very low values.
1 Rate coefficients tend to be difficult to
interpret during long term BOD's
because of progressive changes and
other factors.
a The relative error of the DO test may
be a large fraction of the incremental
DO change during low rate periods.
b Cell mass may agglomerate under
quiescent test conditions and decrease
nutrient availability.
CH. O. bod. 56c. 8. 68
35-1
-------
Effect of Some Variables on the BOD Test
c It Is not likely that recycled nutrients
under aerobic test conditions will ^ 3
have as much effect as recycle from
anaerobic benthic deposits in a ^
stream,
2 The BOD result tends to underestimate ^ • n§
deoxygenation relative to surface water = 07
behavior because of interchanges, k q* q,.
turbulence, biota, and boundary effects. ® q! 04
» 0.03
|J
<
> 0. 02
FIGURE I
VARIATION IN k" WITH CHANCE IN TEMPERATURE
II TEMPERATURE
A Effect on Oxidation Rate
Temperature is one of the important con-
trolling factors m any biological system.
In the BOD reaction, changes in tempera-
ture produce acceleration or depression
of the rate of oxidation. Figure 1 shows
the changes in the value of k at tempera-
tures from 0 - 25°C on a common
wastewater.
B Test Temperature
In the BOD test procedure an arbitrary
temperature is usually selected for
convenience even though a wide temperature
range exists under natural conditions.
Incubation of the test containers at 20°C
for the whole period is now accepted
practice in the U.S., 18. 5°C is preferred
in England. Camp (ASCE, SA5 911, Oct.
65) recommended light and dark bottle
immersion in the stream.
C Temperature Correction
When it is necessary to calculate the rate
of oxidation at a temperature other than
20°, the following relationship may be
used
Hi- e (Ti " t2>
k2
where:
kj = rate coefficient at temperature
kg = rate at coefficient at temperature Tj
0 = temperature coefficient, for which
Streeter and Phelps obtained the value
1. 047. 8 changes with temperature, it
appears to be higher in the range of
5-15°C than in the range of 30 to 40°C.
The value given refers to 15-30°.
The cited temperature coefficient appears
reasonable for household wastes. It may
not apply for other wastes where developing
or seed organisms may not tolerate tem-
perature changes as readily. A given
temperature coefficient should be checked
for applicability under specified conditions.
IU pH
A The organisms involved in biochemical
conversions apparently have an optimum
response near a pH of 7.0 providing other
environmental factors are favorable, a pH
range of about 6.5 to 8. 3 apparently is
acceptable (Figure 2). Reactivity is likely
to be significantly lower on both sides of the
acceptable pH range but microbial adapta-
tion may extend the limits appreciably.
For example, trickling filters have operated
with better than 50% treatment efficiency
at pH 3 and 10 after adaptation.
35-2
-------
Effect of Some Variables on the BOD Test
100 — Figure 2
Z D
a >, 80 -
s 8
c
a>
S.
Adjustment of Concentrated Samples
When wastes are more acid than pH 6. 5 or
more alkaline than pH 8. 3, adjustment to
pH 7.2 is advisable before reliable BOD
values can be obtained.
C Dilution Samples
Standard dilution water is buffered at pH
7.2. Sample-dilution water mixtures should
be checked to make sure that the sample
buffer capacity does not exceed the capacity
of the dilution water for pH adjustment.
B Standard Methods Dilution Water
The dilution water specified for the BOD
test approximates USGS estimates for an
average U.S. mineral content of surface
water except for added phosphate buffer.
It is assumed to provide essential mineral
nutrients for most wastewaters but cannot
be expected to meet requirements for
grossly deficient wastewater nutrients both
mineral and organic. Ruchhoft (S. W. J.
13:669, 1941) summarized committee action
leading to the present dilution water.
C Other Dilution Considerations
There is a trend toward the use of receiving
water, storage-stabilized if necessary, to
evaluate waste behavior. It is advisable
to minimize dilution and consider the
nutrient level likely in the receiving water
as most valid. Any change in the environ-
ment, such as dilution, upsets the
microbial balance and requires adaptive
changes.
IV ESSENTIAL MINERAL NUTRIENTS
A Importance
In 1932 Butterfield reported on the role of
certain minerals in the biochemical oxidation
of sewage and concluded that deficient
minerals often upset metabolic response.
In addition, he found that inadequate nitrogen
and/or phosphorus was a common cause of
low BOD results in industrial wastewaters.
(Figure 3)
Figure 3
Normal
Lacking N h P
4 5
Time In Days
Effect of Mineral Nutrients on BOD
V MICROBIOLOGICA L POPULATION
A Need for Complex Flora and Fauna
Butterfield, Purdy, and Theriault (Pub.
Health Rep. 393, 1931) demonstrated that
an isolated species of organisms was not
as effective in biological stabilization as
a variety of species. Figure 4 summarizes
some of their data. Bhatta and Gaudy
(ASCE, SA3, 91:63, June 1965) reinvestigated
this factor. Many studies have emphasized
the need for a mixed biota in the BOD test.
It appears that bacteria are capable of
varied activities, but all species are not
capable of synthesizing all required nutrients.
Certain bacterial species may be capable
of producing enzymes, amino acids, or
growth factors needed for their use and by
other species for optimum performance.
It has been shown that oxygen demand
becomes minimal when some limit of
bacterial population has been reached.
Predation prevents such an approach to
maximum numbers and maintains a con-
tinuing bacterial growth and recycle of
nutrients among a mixed population. The
net effect is a symbiotic relation among
mixed organisms tending to enhance the
rate of stabilization or utilization of
oxygen as in the BOD test.
35-3
-------
Effect of Some Variables on the BOD Test
B Organism Adaptation
1 Early investigations in relation to the
BOD test considered domestic wastewaters
primarily. The saprophytic organisms
involved in stabilization either were
present in adequate numbers or quickly
multiplied to attain effective populations.
2 The period of adjustment required to
shift enzyme production needed to utilize
an energy source different from that
previously utilized or to shift population
variety from that favored by one food to
that favored by another food is con-
sidered an adaptation period. Dilution,
temperature, oxygen tension, pH,
nutrient type, inhibitory substances,
light and other changes all are common
inducements for microbial adaptation.
Mutation of organisms may be encountered
during adaptation but usually is not a
factor.
3 The developments in industry and
technology have resulted in discharge
of new and more varied wastewater
constituents. Microorganisms may
adapt themselves to the use of a new
substance as an energy source providing
the energy and environment are favor-
able. The receiving stream usually shows
development of an adapted microbiota
for a new or different discharge con-
stituent within hours, days or weeks
after fairly regular discharge. The
time for adaptation depends on the nature
of the constituent, available energy,
tolerance of the organisms, and environ-
mental conditions.
C Seeding
The amount of seed and its selection must
be determined experimentally. The most
effective inoculant would be that which
would produce the maximum BOD response
with minimum lag period and negligible
seed demand. This would mean some
maximum population adapted to feed and
conditions at a minimum equilibrium energy
nutrient supply.
1 Figure 5 indicates corrected BOD
progression on a synthetic feed with
river water and stale sewage inoculants
at several concentrations. The river
water resulted in higher BOD with
negligible lag and seed correction. The
seed correction at 20% concentration
of inoculant was less than 0.3 mg.
DO/1 at 5 days. It would be possible to
use this river water as a diluent without
excessive oxygen loss to produce more
valid BOD progression for that receiving
water. The lower wastewater inoculant
concentration resulted in a definite BOD
lag. Higher wastewater concentrations
produced comparable BOD progression
earlier but resulted in high seed
corrections and lowered availability of
dissolved oxygen for the sample.
2 A good secondary treated effluent
produced results similar to river water
inoculation with higher seed corrections
per increment of applied inoculant.
Soil suspensions also are very effective
sources of seed organisms with minor
seed corrections if they are reasonably
stabilized surface soils.
3 It appears that the BOD progression
most nearly indicating receiving water
oxidation would be one based upon
receiving water dilution or inoculated
with organisms from it.
4 A new or unusual wastewater may
require adapted organisms not present
in sufficient numbers in the receiving
water. Development of an adapted seed
from soil suspensions, plant effluents
or receiving water may be necessary to
evaluate oxidation potential in a plant
or receiving water at some future time.
Enrichment culture technique is bene-
ficial where small concentrations of the
test wastewater are applied regularly
with increases in wastewater concen-
trations as BOD or respiration activity
indicates increasing tolerance and
oxidation of the test waste. Both time
and concentration limits are useful to
characterize the wastewater and its
acceptability for biological stabilization.
35-4
-------
Effect of Some Variables on the BOD Test
g
All forms In river water —
Mixed ooctena & plankton
Pure culture B Aerogenes & plankton
Mixed culture bacteria —
Pure culture B Aerogenes
10 II 12 U 14
7
8
9
1
3
4
6
0
S
Time in Days
hffet.1 of Biological Forma on Oxygen Depletion
Figure 4
DO DEPLETION VS SEED
6 CONCENTRATION 8 TYPE (2% glucose-glutamic acj
5
RIVER WATER
STALE W W
4
3
a
0 5% STALE SEW -
0 2%
0)%
1-20% RIVER WATER
I
2
3
4
S
DAYS
6
7
Figure i
5 It must be recognized that BOD
progressions are most likel) to err
on the low side. A meaningful BOD
test should seek the highest consistent
oxygen demand feasible for sample and
conditions.
D Algae
When large numbers of algae are present
in surface waters, they produce significant
changes in the oxygen content. Under the
influence of sunlight excess oxygen is
produced while a net deficit occurs in the
dark. The result is a wide variation in
surface water DO depending on sample
time.
When stream samples containing algae are
incubated in the laboratory the algae
survive for a time, then die because ot the
lack of light. Short-term BOD determina-
tions may show the influence of oxygen
production by the algae. When the algae
die, they release the stored organic load
for recycle and increase the BOD. There-
fore, samples incubated in the dark may
not be representative of the deoxygenation
process in the stream, since the benefits
of photosynthesis are lacking. Conversely,
samples incubated in the light, under
conditions of continual photosynthesis,
will yield low BOD values.
The influence of algae on BOD is one of
the most difficult variables to evaluate.
More research is needed to develop
satisfactory methods for the accurate
determination of BOD in the presence oi
large numbers of algae. Light and dark
bottle incubations suggest the magnitude
of effects.
IV TOXICITY
A Effect
Since satisfaction of the BOD is accom-
plished through the action of microorgan-
isms, the presence of toxic substances
will result in depression of the oxidation
rate. In many cases, toxicity will
produce a lag period, until tolerant
organism activity becomes significant.
Figure 6 shows the effect of cyanide on the
BOD curve. A prominent lag period is
exhibited in the 2 ppm curve, while at
10 ppm the lag extends beyond the fifth day.
An activated sludge maj be adapted to work
effectively in degradation of60mgCN/l.
5
-------
Effect of Some Variables on the BOD Test
t—i—i—ry i—i—i—r
Table I
«///, ¦//////'/////.'/////////A'fflfiffiffib.
12 3 4
Time In Days
Effect of Cyanide on BOD of Domestic Sewage
(2% Sewage in Formula C Dilution Water)
Figure 6
Heavy metals have similar effects depending
on history and environment. The effects of
copper and chromium are illustrated in
Figure 7.
Waste
conc.
Depletion
5 day BOD
10%
3.51
35
5%
4.53
91
2%
2. 80
140
1%
1.52
152
0.5%
0. 74
148
VH NITRIFICATION
A Mechanism
The oxidation process, as exemplified by
the equation:
100
t
CHROMIUM (VII
20
i-
8
1 l'
3
0
G
9
EFFECT OF HE A \ \ METALS OV BOD
Figure 7
B Detection
In laboratory determinations of BOD the
absence of toxic substances including
chlorine must be established before the
results can be accepted as valid.
Comparison of BOD values for several
dilutions of the waste will indicate the
presence or absence of toxicity. In Table 1
the calculated BOD for the dilutions show
higher values in the more dilute concen-
trations. It is apparent that toxicity was
present and that the toxic effect was diluted
out at a waste concentration of 2% or less.
y = L (l-10_kt)
presumably involves the oxidation of
carbonaceous matter:
o2
C H O — C02 + HzO
The rate coefficient is normally high, giving
nearly complete oxidation in a few days.
When nitrogenous material is present its
oxidation can be shown as:
°2 - °2 -
NH3 - no2 - no3
Nitrogen oxidation may be delayed for
several days during BOD tests unless
suitable micro-biota are initially available.
Under some circumstances these two
oxidations can proceed simultaneously and
the resultant BOD curve will be a com-
posite of the two reactions.
yt = ^Lc(l-10"kct ) + Ln (l-10"knt)J
where yt «¦ the simultaneous BOD of the car-
bonaceous and nitrogenous phases
kc and kn = the rate coefficients appli-
cable to the carbonaceous and nitrogenous
materials respectively.
35-6
-------
Effect of Some Variables on the BOD Test
L and L a the ultimate oxygen demands
characteristic of the two phases respectively.
This is the general formula for any system
characterized by two simultaneous reactions.
Principal conditions governing simultaneous
carbon and nitrogen oxidation:
1 Presence of an effective nitrifying
culture at the beginning of the test
interval (nitrifiers grow relatively
slowly).
2 Maintenance of adequate DO, believed
to be a minimum of 0. 5 to 1. 0 mg/1,
for nitrifier activity.
3 Available nitrogen - in excess of that
required for synthesis. This is believed
to require a minimum of about 7 mg/1
to support active nitrification on a
continuous basis.
4 Nitrifiers appear to be more sensitive
to toxicity than most saprophytic
organisms, hence are likely to be
inhibited more readily. This is
particularly evident during nitrite to
nitrate conversion.
B It may require 5 to 10 days to establish
nitrification if the population was not
nitrifying initially. This is the basis for
the sequential carbonaceous and nitrogenous
oxidation of sewage oxidation.
1 Effects on the BOD curve indicate a
typical pattern such as in Figure 8.
The influence of nitrification m the
production of a secondary rise in the
BOD curve is so well known that any
secondary rise may be erroneously
attributed to nitrification whether or
not nitrification was involved. Actually,
a secondary rise in the curve may be
due to any oxidation system assuming
dominance after the initial oxidation
system has been completed.
2 The nitrification phenomena occurs
simultaneously in many streams,
treated effluents or partially stabilized
samples. The designation of a secondary
BOD rise to nitrification should be
based on analysis, not curve shape.
C The extent of nitrification is conclusively
shown only by periodic analysis of
ammonia, organic, nitrite and nitrate
nitrogen. The conversion of ammonia
and organic nitrogen to oxidized nitrogen
is a definite indication of nitrification.
D Nitrification Inhibition
Plant efficiencies from a BOD standpoint
can be erroneous because nitrification
generally is not established during the
usual incubation of influent samples but
may be a major factor in effluent
incubations. It requires about 2 times
the oxygen to convert NH^ -N to NO^ -N
as to convert C to C02 hence this is a
major fraction of stream oxygen use.
Most secondary treated effluents are
characterized by a larger fraction of
carbon than nitrogen removal which
accentuates the problem.
Pasteurization of samples, methylene
blue, chromium, and acid treatment
followed by neutralization have been used
to inhibit nitrification for estimation of
carbonaceous BOD only. Any inhibition
of nitrification also produces a change in
the sample or its behavior and may
partially inhibit carbonaceous oxidation.
Nitrification is a factor in stream self-
purification and treatment. It does not
appear realistic to alter it for convenience.
The most realistic approach to carbon-
aceous oxidation is the measurement of
COg or COD.
e
a
Figure 8
35-7
-------
Effect of Some Variables on the BOD Teat
vm EFFECT OF DILUTION
When a series of dilutions are made on a BOD
sample usually the results vary to the extent
that only an approximate BOD value is obtained.
A For example, in Table 2, 1%, 2% and 4%
concentrations of sample were used. The
4% concentration became anaerobic before
the end of 5 days. The 5-day BOD of the
1% concentration was 270 and that of the
2% concentration was 245.
B Statistically one value is more reliable
than the other.
Variation in results with dilution is a
difficult problem without a precise answer.
Possibility of inhibition at high concen-
trations and of limitation of species at
low concentrations may tend to produce
an entirely different selection of population
and of oxidation. Frequently the best
answer is that value nearest the stream
dilution
Table 2
INTERPRETATION OF BOD DATA
Dilution
1%
2%
Difference
DO depletion
5. 5 mg/1
3. 3 mg/1
2. 2 mg/1
The difference in depletion between 1 and
2% dilutions is 2.2 mg/1. This difference
may be attributed to an additional 1% of
Sample added to the original 1%. If the
difference is multiplied by the dilution
factor of 100 to obtain the BOD, the result
is 220 mg/1 which is closer to the 245
obtained at 2% dilution than to 270 obtained
at 1% dilution. Standard Methods indicates
that preferred BOD results should have a
depletion of 40 to 70% of the initial DO.
3.3/8.2 = 0.40 and 5.5/8.2 =¦ 0.67
hence both values are within acceptable
limits although the larger of the two
depletions is more acceptable.
Sample conc.
DO
Depletion
BOD
Initial
8. 2
-
-
Final.
1%
5. 5
2. 7
270
2%
3. 3
4. 9
245
4%
0. 0
Complete
- •
ACKNOWLEDGEMENT:
Certain portions of this outline contains
training material from prior outlines by
D.G. Ballinger and J. W. Mandia.
This outline was prepared by F. J. Ludzack,
Chemist, National Training Center, FWQiA,
Cincinnati, OH 45226.
35-8
-------
CHEMICAL OXYGEN DEMAND AND COD/BOD RELATIONSHIPS
I DEFINITION
A The Chemical Oxygen Demand (COD) is
an estimate of the proportion of the sample
matter susceptible to oxidation by a
strong chemical oxidant. Standard
Methods, 12th Edition, p 510, specifies
organic material which is generally the
situation but not necessarily applicable.
B A variety of terms have been and are used
for the test described here as COD:
1 Oxygen absorbed (OA) primarily in
British practice.
2 Oxygen consumed (OC) preferred by
some, but unpopular.
3 Chemical oxygen demand (COD) current
preference.
4 Complete oxygen demand (COD)
misnomer.
5 Dichromate oxygen demand (DOC)
earlier distinction of the current pre-
ference for COD by dichromate or a
specified analysis such as Standard
Methods.
6 Others have been and are being used.
Since 1960, terms have been generally
agreed upon within most professional
groups as indicated in I-A and B-3 and
the explanation in B-5.
C The concept of the COD is almost as old
as the BOD. Many oxidants and varia-
tions in procedure have been proposed,
but none have been completely
satisfactory.
1 Cenc sulfate has been investigated,
but in general it is not a strong
oxidant.
2 Potassium permanganate was one of
the earliest oxidants proposed and
until recently appeared in Standard
Methods (9th ed.) as a standard pro-
cedure. It is currently used in
British practice as a 4-hr. test at
room temperature.
a The results obtained with perman-
ganate were dependent upon concen-
tration of reagent, time of oxidation,
temperature, etc., so that results
were not reproducible.
3 Potassium iodate or iodic acid is an
excellent oxidant but methods employing
this reaction are time-consuming and
require a very close control.
4 A number of investigators have used
potassium dichromate under a variety
of conditions. The method proposed
by Moore at SEC is the basis of the
standard procedure. 2' Statistical
comparison^ with other methods are
described.
5 Effective determination of elemental
carbon in wastewater was sought by
Buswell as a water quality criteria.
a Van Slyke^ described a carbon
determination based on anhydrous
samples and mixed oxidizing agents
including sulfuric, chromic, iodic
and phosphoric acids to obtain a
yield comparable to the theoretical
on a wide spectrum of components.
b Van Hall, et al., used a heated
combustion tube with infrared
detection to determine carbon quickly
and effectively by wet sample
injection.
6 Current development shows a trend to
instrumental methods automating
CH. O oc. 10c. 3. 69
36-1
-------
Chemical Oxygen Demand and COD/BOD Relationships
conventional procedures or to seek
elemental or more specific group
determination.
H RELATIONSHIP OF THE COD TEST WITH
OTHER OXIDATION CRITERIA IS
INDICATED IN TABLE 1.
A Table 1
Test
Test
Temp. °C
Reaction
time
Oxidation
system
Variables
BOD
20
days
Biol. prod.
Enz. Oxidn.
Compound, environ-
ment, biota, time,
numbers. Metabolic
acceptability, etc.
COD
145
2 hrs.
50% H2S04
K2Cr207
May be cata-
lyzed
Susceptibility of
the test sample to
the specified
oxidation
IDOD
20
15'
Diss. oxyg.
Includes materials
rapidly oxidized by
direct action,
Fe , SH.
Van Slyke
Carbon detn.
400+
1 hr.
H3PO4
HIO3
H2so4
K2Cr207
Anhydrous
Excellent approach
to theoretical oxi-
dation for most
compounds (N-nil)
Carbon by
combustion
+IR
800
seconds
Oxygen atm.
catalyzed
Comparable to
theoretical for
carbon only.
Chlorine
Demand
20
20 mm.
HOC1 soln.
Good NH3 oxidn.
Variable for other
compounds.
B From Table 1 it is apparent that oxidation
is the only common item of this series of
separate tests.
1 Any relationships among COD & BOD
or any other tests are fortuitous be-
cause the conditions of test tend to give
results indicating the susceptibility of
a given sample to oxidation under
specified conditions that are different
for each test.
2 If the sample is primarily composed
of compounds that are oxidized by
both procedures (BOD and COD) a
relationship may be established.
36-2
-------
Chemical Oxygen Demand and OOP/BOD Relationships
a The COD procedure may be sub-
stituted (with proper qualifications)
for BOD or the COD may be used
as an indication of the dilution
required for setting up BOD
analysis.
b If the sample is characterized by a
predominance of material that can
be chemically, but not biochemi-
cally oxidized, the COD will be
greater than the BOD. Textile
wastes, paper mill wastes, and
other wastes containing high con-
centrations of cellulose have a
high COD, low BOD.
c If the situation in item b is reversed
the BOD will be higher than the
COD. Distillery wastes or refinery
wastes may have a high BOD, low
COD, unless catalyzed by silver
sulfate.
d Any relationship established as in
2a will change in response to
sample history and environment.
The BOD tends to decrease more
rapidly than the COD. Biological
cell mass or detritus produced by
biological action has a low BOD
but a relatively high COD. The
COD/BOD ratio tends to increase
with time, treatment, or conditions
favoring stabilization.
Ill ADVANTAGES AND LIMITATIONS OF
THE COD TEST(2) AS RELATED TO BOD
A Advantages
1 Time, manipulation, and equipment
costs are lower for the COD test.
2 COD oxidation conditions are effective
for a wider spectrum of chemical
compounds.
3 COD test conditions can be standardized
more readily to give more precise
results.
IV
COD results are available while the
waste is in the plant, not several
days later, hence, plant control is
facilitated.
COD results are useful to indicate
downstream damage potential in the
form of sludge deposition.
The COD result plus the oxygen equiva-
lent for ammonia and organic nitrogen
is a good estimate of the ultimate BOD
for many municipal wastewaters.
B Limitations
Results are not applicable for estimating
BOD except as a result of experimental
evidence by both methods on a given
sample type.
Certain compounds are not susceptible
to oxidation under COD conditions or
are too volatile to remain in the oxida-
tion flask long enough to be oxidized.
Saturated hydrocarbons, pyridine, and
toluene are examples of materials with
a low analytical response in the COD
test.
Dichromate in hot 50% sulfuric acid
requires close control to maintain
safety during manipulation.
Oxidation of chloride to chlorine is not
closely related to BOD but may affect
COD results.
It is not advisable to expect precise
COD results on saline water.
BACKGROUND OF THE STANDARD
METHODS COD PROCEDURE
The COD procedure^ ^ considered dichro-
mate oxidation in 33 and 50 percent sul-
furic acid. Results indicated preference
of the 50 percent acid concentration for
oxidation of sample components. This is
the basis for the present standard
procedure.
36-3
-------
Che"^cal Oxygen Demand and COD/BOD Relationships
B Muers^ suggested addition of silver
sulfate to catalyze oxidation of certain
low molecular weight aliphatic acids and
alcohols. The catalyst also improves
oxidation of most other organic components
to some extent but does not make the COD
test universally applicable for all chemical
pollutants.
C The unmodified COD test result (A) includes
oxidation of chloride to chlorine. Each mg
of chloride will have a COD equivalent of
0. 23 mg. Chlorides must be determined
in the sample and the COD result corrected
accordingly.
1 For example, if a sample shows 300
mg of COD per liter and 200 mg Cl~
per liter the corrected COD result will
be 300 - (200 x 023) or 300 - 46 = 254
mg COD/1 on a chloride corrected basis.
2 Silver sulfate addition as a catalyst
tends to cause partial precipitation of
silver chloride even in the hot acid
solution. Chloride corrections are
questionable unless the chloride is
oxidized before addition of silver sul-
fate, i. e. , reflux for 15 minutes for
chloride oxidation, add Ag2SO^, and
continue the reflux.
( 7)
D Dobbs and Williams * proposed prior
complexation of chlorides with HgS04 to
prevent chloride oxidation during the test.
A ratio of about 10 of Hg to 1 of CI" (wt.
basis) appears essential. The CI" must
be complexed in acid solution before addi-
tion of dichromate and silver sulfate.
1 For unexplained reasons the HgSO^
complexation does not completely
prevent chloride oxidation in the
presence of high chloride concentrations.
2 Factors have been developed to provide
some estimate of error in the result
due to incomplete control of chloride
behavior. These tend to vary with the
sample and technique employed.
E It is not likely that COD results will be
precise for samples containing high
chlorides. Sea water contains 18000 to
21000 mgCl"/1 normally. Equivalent
chloride correction for COD exceeds
4000 mg/1. The error in chloride
determination may give negative COD
results upon application of the correction.
Incomplete control of chloride oxidation
with HgS04 may give equally confusing
results.
HgSOa appears to give precise results
for COD when chlorides do not exceed
about 2000 mg/1. Interference in-
creases with increasing chlorides at
higher levels.
F The 12th edition of Standard Methods re-
duced the amount of sample and reagents
to 40% of amounts utilized in previous
editions. There has been no change in
the relative proportions in the test. This
step was taken to reduce the cost of pro-
viding expensive mercury and silver sul-
fates required. Results are comparable
as long as the proportions are identical.
Smaller aliquots of sampe and reagents
require more care during manipulation
to promote precision.
G The FWPCA Official Interim Methods
1 The FWPCA Official Interim Methods
(September 1968) for high level COD
specifies the unmodified Standard
Methods procedure.
2 For samples with a COD range of 10-90
mg/1 the method is modified to employ
0. 025 N dichromate and ferrous ammonium
sulfate with other reagents as in 1. 10 ml
of sample is t reated with 2 ml of silver
free acid and mercuric chloride and mixed
10 ml of dichromate and 18 ml of H2SO4
containing Ag2S04 are added and mixea
with reflux and back titration as in 1.
Acid concentration is the same but
sample-dichromate volumes are different
from 1.
3 When the sample contains more than
100 mg pl7l the minimum accepted COD
will be 250 mg/1, and the procedure is
the same as 1 except 50 ml of sample,
25 ml of dichromate solution and 75 ml
of H2S04~Ag2S04 are used.
V The precision of the unmodified COD result,
shows a standard deviation of +4% of the mean
on low chloride samples. Silver sulfate modi-
fied COD results are likely to show a standard
deviation about twice that without catalysis, due
to questionalbe chloride behavior. The deter-
mination of chloride frequently shows a co-
efficient of variation (s/x) of 10 to 157c, hence
high chloride samples result in COD precision
controlled more by chloride behavior than
organic oxidation.
36-4
-------
Chemical Oxygen Demand and COD/BOD Relationships
VI
B
REMARKS PERTINENT TO EFFECTIVE
COD DETERMINATIONS INCLUDE:
Sample size and COD limits for 0. 25 N
reagents are approximately as given.
For 0. 025 N reagents multiply COD by
0.1. Use the weak reagent for CODs
less than 100 mg/1.
Sample Size
20 ml
10 ml
5 ml
mg COD/1
2000
4000
8000
D
Most organic materials oxidize relatively
rapidly under COD test conditions. A
significant fraction of oxidation occurs
during the heating upon addition of acid.
The color change of dichromate after
acid addition indicates the approximate
fraction of dichromate remaining. If
the mixed sample color changes from
yellow to green after acid addition the
sample was too large. Discard without
reflux and repeat with a smaller
aliquot until the color after mixing does
not go beyond a brownish hue. The
dichromate color change is less rapid
with sample components that are slowly
oxidized under COD reaction conditions.
Chloride concentrations should be known
for all test samples and results inter-
preted accordingly.
Special precautions advisable for the
regular COD procedure and essential
when using 0. 025 N reagents include:
1 Keep the apparatus assembled when
not in use.
2 Plug the condenser breather tube with
glass wool to minimize dust entrance.
3 Wipe the upper part of the flask and
lower part of the condenser with a
wet towel before disassembly to
minimize sample contamination.
Steam out the condenser after use for
high concentration samples and periodi-
cally for regular samples. Use the
regular blank reagent mix and heat,
without use of condenser water, to
clean the apparatus of residual oxidiz-
able components.
Distilled water and sulfuric acid must
be of very high quality to maintain low
blanks on the refluxed samples for the
0. 025 N oxidant.
ACKNOWLEDGEMENT:
Certain portions of this outline contain
training material from prior outlines by
R. C. Kroner, R. J. Lishka, and J. W Mandia.
REFERENCES:
1 Moore, W. A., Kroner, R. C. and Ruchhoft,
C. C. Anal. Chem. 21:953 1949.
2 Standard Methods, 12th Edition, 1965
p. 510, APHA
3 Moore, W. A., Ludzack, F.J and
Ruchhoft, C.C. Anal. Chem. 23:1297,
1951.
4 Van Slyke, D. D and Folch, J.J. Biol.
Chem. 136:509 1940.
5 Van Hall, C. E , Safranko, J. and Stenger,
V.A., Anal. Chem. 35:315 1963.
6 Muers, M. M. J. Soc. Chem. Ind. (London)
55:711 1936.
7 Dobbs, R.A. and Williams, R T. , Anal.
Chem. 35:1064 1963
This outline was prepared by F. J. Ludzack,
Chemist, National Training Center,
FWQA, Cincinnati, OH 45226.
36-5
-------
PUMP MAINTENANCE
I INTRODUCTION
A Pumping is a fact of life in wastewater
treatment plant operation. You probably
have sewage pumps, air pumps, sludge
pumps, proportioning pumps for oil, fuel,
or chemicals, recirculating pumps for
gas process waters or sludge. Some pumps
are intended for continuous operation,
some for intermittant operation. You are
likely to have many different sizes and
several different types of pumps available
for different purposes.
B You will have to learn to live with pumps.
With appropriate lubrication and care of
them, your life will be easier and much
more productive.
I ORGANIZATION FOR PUMP MAINTENANCE
A It is assumed that your plant has been
checked out for service and is in operation.
Start up routine is a function of the
representatives of the plant facility, the
consultant, the contractor and the equipment
manufacturer, or supplier. Hopefully, you
were a key part of this phase of operation
to learn as much as possible from it.
B Your plant records should contain specific
instructions, drawings and descriptive
material for each pump in service.
Assemble and file them in an orderly
fashion so that you can locate them when
you need them.
C Each pump should have a record card
including make, model serial number and
date of installation; name of the supplier
or service representative, and lubrication
instructions. This card should be posted
preferably in a suitable place in the pump
vicinity so that a running record on it can
be maintained. Date of lubrication, cleanup,
notes on operating problems, and initials
of the individual making the entry are
regularly sought. As soon as one card is
filled, permanently file it and replace it
with a new record card.
I PUMP BEARINGS
Pump bearings are one of the major sources
of trouble. Daily observations are necessary
to avert trouble.
A Any irregularity in noise vibration
temperature or flow is an indication of
trouble and should be closely watched.
This is applicable not only to pumps but
to pump drivers as well.
B Lets assume that you are starting a new
pump or restarting one that has received
a cleanout or overhaul. Check for proper
greasing, pump rotation and alignment.
1 Check bearing temperature for the first
hour of operation or until they reach a
stable running temperature under
conditions of use. Be sure that an
approved bearing temperature device
is used - hand contact may be handy
but it is not advisable because a "cooked"
hand is not very useful for you or for the
record. If the temperature does not
stabilize within a reasonable running
range find out why bfcf~-e serious
difficulty develops.
2 If the temperature stabilizes in an
acceptable range, you probably are in
business for 1000 to 2000 hours of
operation depending upon severity of
service such as dampness, corrosivity,
abrasives, etc.
3 Learn to recognize the sound of the unit
under favorable use conditions. Air
leakage into the suction side, overloads,
discharge obstructions, loose anchorage
and many other problems may be
detected by sound changes.
C Greasing during service depends on the
operation and the equipment.
1 For 24 hour service, add grease every
6-12 weeks. Clean out bearings and
bearing housings every 12-18 months
with hot (200-240 F) kerosene flushing.
Follow with a light mineral oil flush
and repack the bearing with the
recommended grease.
2 For 8 hr/day service, add grease every
6-8 months.
3 For light duty or standby service, run
pumps for 1 to 2 hours every month to
prevent rust accumulation. Have the
bearings cleaned aud flushed (hot
kerosene 200-240 °F) once yearly and
repacked with recommended grease to
SE.TT.eq. 6.8.70
37-1
-------
Pump Maintenance
prevent damage due to oxidation of
grease.
4 Grease would normally be a good
quality No. 2 moisture resistant
variety for normal temperatures.
A No. 1 grease is used for higher
speeds or lower ambient temperatures.
Where bearing temperatures are up
to 150 F; a lime base inhibitor is
normally used and a lithium base
generally used where the bearing
temperatures are higher than 150°f.
Check the pump manufacturers'
recommendations.
5 For bearings equipped with grease
plugs, remove both takeout plugs and
do not over fill during repacking.
Increased temperatures during running
will expand the grease and cause a
dangerous pressure rise after replacing
plugs which is likely to damage the
bearing. It may be advisable to run the
unit for a short time before reinserting
the second plug to get rid of excess
grease.
6 A constant level oiler is usual for oil
lubricated bearings. A high quality
turbine or hydraulic oil containing rust,
oxidation, and foam inhibitors is
recommended. Check equipment and
lubricant manufacturers recommendation.
Normally a 10-W oil is used for bearing
temperatures of 125 to 145^ and a 20-W
oil for bearing temperatures of 145 to
180°f. Note - The oiler level must be
as shown on drawings or bearing housing
for a high oil level is as bad as
overgreasing a bearing. A complete
oil change is recommended every 6 to
8 months of average operation. More
often if the atmosphere is damp and
corrosive as it usually is in sewage
treatment plants.
D Long term storage without operation
requires special care on either grease or
oil lube bearings to prevent bearing
troubles. If a pump is likely to be on
standby for more than one month:
1 Request the manufacturer to prepare
it for long term storage or
2 Coat shaft and bearings with heavy
grease to prevent rusting.
3 Before use, clean by hot flushing as
described in III. C.I. and replace
with the recommended lubricant.
4 Almost all initial bearing failures are
traceable to neglect of storage
considerations.
IV PUMP PACKING
A Pump packing may be carefully done
either at the factory or by in-house
replacement. Its service life generally
depends on careful adjustment and checking
of conditions to insure that it does prevent
gross pump leakage without excessive
heating or wear on the shaft sleeves.
B Remember that the packing of any pump
is cooled and lubricated by the leakage of
liquid from the packing or "stuffing box. 11
1 Never tighten the packing gland so that
leakage is stopped completely. A steady
rate of 10-15 drops/minute of leakage
through the packing is the proper rate.
2 Never tighten packing on a unit that is
not running .
3 Start the pump, allow it to leak fairly
rapidly for a few minutes running.
Tighten the packing gland evenly and a
little at a time allowing it to run for a
few minutes after each take-up stage.
(Use hand tightening)
C Once the packing is old and worn or leakage
cannot be controlled readily by packing
gland adjustment, repack the stuffing box -
never add one more packing ring to take
up the "slack" and give a bit more adjustment.
1 Remove all old packing, the lantern
ring and/ or seal cage. Careful - these
are generally "stuck" in place. There
is no easy removal. Your service
representative generally can supply
tips to help you remove packing in your
particular type of pump without damaging
the shaft sleeve or housing.
2 After removal of stuffing, clean the box
thoroughly. Inspect the box, shaft sleeve,
lantern ring, and/or seal cage. Make
certain that the shaft sleeve is not
unduely worn or damaged. You will
waste time and material repacking if
it is.
3 Cut the packing about 1/16 inch longer
than measured - this will insure that
the outside diameter of the packing
ring will hug the stuffing box rather
than the shaft sleeve and cause
37-2
-------
Pump Maintenance
excessive wear. Use a sharp cutting
tool to get a clean cut. The usual
packing for water and sewage service
is braided graphited asbestos. Never
use flax as it will result in rapid shaft
sleeve wear. Check with the manufacturer
or service representative.
4 When inserting packing, push the first
ring all of the way back into the housing
evenly. Rotate each subsequent ring
so tha^the cut ends are staggered 90
to 180 . Push each one all of the way
back into the housing before starting
the next. Make certain that the lantern
ring or seal cage is directly under the
seal water connection. Continue adding
packing rings individually according to
specifications. Replace packing gland.
Take up slack, then back up to a loose fit.
5 Inspect the pump installation before
startup. Are your valves, power circuits,
pump and lines ready to go? If so, turn
on the seal water and start the pump.
Let the stuffing box leak freely for 10-15
minutes, then gradually tighten the packing
nuts by hand. Watch the temperature
rise; if packing nuts are tightened too
rapidly, the packing will heat, glaze and
possibly score the shaft sleeve.
6 Caution - never tighten the packing gland
so that all leakage is stopped. A slow
constant drip is what you want. Check
daily and adjust as needed.
V SEMI ANNUAL OR ANNUAL INSPECTIONS
A Check the running records. Have the units
been serviced on schedule7 Have there
been notations of characteristics that
suggest operating difficulty later7
B Clean the bearings and replace with grease
or oil as specified on the running record.
Replace stuffing box packing after cleaning
the housing as specified on the running
record. Check packing gland leakage and
freeness. Oil and free-up packing gland
nuts and bolts.
C Check capacity and head to determine if
wearing ring clearances are OK. Complete
overhaul is not ordinarily needed unless
problems such as reduction in capacity or
pressure, vibration, high bearing
temperatures are evident.
1 If it is necessary to dismantle the pump.
protect all machined surfaces from
rust or damage, clean and paint casings,
check wearing ring clearances with the
pump manufacturer, check shaft sleeves
and replace if worn. Check fit at the
the impeller hub and condition of the
shaft under the sleeves. Remember
that mismatched or poorly fitting
replacements are likely cause early
failure. Either know what you are
doing or call in someone who does.
VI Some of the more common sources of
trouble are listed below. The operator
often can avoid unnecessary expense
by careful consideration of the causes
outlined.
A Failure to Deliver Water
1 Pump not primed
2 Insufficient speed
3 Discharge head too high (greater than
that for which the pump is rated)
4 Suction lift too high
5 Impeller passages partially clogged
6 Wrong direction of rotation
B Insufficient Capacity
1 Air Leaks in suction piping
2 Speed too low
3 Total head higher than that for which
pump is rated
4 Suction lift too high
5 Impeller passages partially clogged
6 Mechanical defects:
a Impeller damaged
b Wearing rings worn (where applicable)
7 Foot valve too small or restricted by trash
8 Foot valve or suction pipe not immersed
deep enough
C Insufficient Discharge Pressure
1 Speed too low
37-3
-------
Pump Maintenance
2 Air in water
3 Mechanical defects:
a Impeller damaged
b Wearing rings worn (where applicable)
D Pump Loses Prime After Starting
1 Leaky suction line
2 Suction lift too high
3 Air or gases in the liquid
E Pump Overloads Driver
1 Speed too high
2 Liquid pumped of different specific
gravity and viscosity than that for which
pump is rated
3 Mechanical defects
4 Packing gland too tight causing
excessive friction loss in box
F Pump Vibrates
1 Misalignment
2 F oundation not rigid
3 Impeller partially clogged, causing
unbalance
4 Mechanical defects:
a Bent shaft
b Rotating element binds
c Worn bearings
This outline was prepared from materials
supplied by C. M. Robertson, Jr. , Worthington
Corporation, 1077 Celestial Street,
Cincinnati, OH 45202
37-4
-------
ULTIMATE DISPOSAL TO THE ENVIRONMENT
I INTRODUCTION
A Pollutants removed from wastewaters must
be treated in such a way that they will not
pollute the environment,
1 A pollutant is a substance that interferes
with the intended use of the environment.
2 Incineration to reduce volume of organic
wastes must not lead to air pollution.
3 Likewise, the effluent from a scrubber
used to control air pollution from a
furnace must be treated to prevent
water pollution.
4 Only three places to put polluting
substances. Air, land, ocean. Not
in surface waters.
5 Pollutant substances must be rendered
innocuous either by dilution below
background level or by locking up in
precipitates.
B Ocean Disposal
1 Barge to deep water and sink to bottom.
Lock up on bottom.
2 Ocean pipeline to deep water and sink
solids. Dilute and lock up. West Coast.
3 Ocean diffuser into well mixed area.
Dilute, Gulf and East Coast Continental
Shelf.
4 Food chains may concentrate poisons
killing larger species.
C Land Disposal. Fill.
1 Not suitable for soluble substances
such as salts.
2 Needs dewatering to produce solid that
will bear a load. Useful for insoluble
inorganic wastes.
3 Organics will putrefy and decay and
may produce foul seepage and sub-
sidence of the surface.
D Land Disposal. Surface.
1 Not suitable for solubles except nutrients
in quantities utilized by plants.
2 Low cost dewatering, can handle liquid
sludges.
3 Low cost oxidation of organic matter.
4 Many elements locked up on soil
minerals.
5 Improves soil for agriculture and
forestry.
6 Chicago planning long pipeline to carry
sludge to waste lands.
E Land Disposal. Wells.
1 Wells into porous formations are
unsuitable for sludges or liquids con-
taining filterable solids.
2 Useful for salt disposal into saline
aquifers.
3 May leak out and contaminate other
waters.
4 Large volumes may produce earthquakes
and land movement.
F Polluting Substances
Consider pollutants on an element-by-
element basis. Fortunately do not have
101 problems as most elements will not
be pollutants.
II ORGANIC SUBSTANCES
A Carbon, Hydrogen, Oxygen, Nitrogen,
Phosphorus, Sulfur, Ash.
AWT. UD. la. 12.68
I
38-1
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Ultimate Disposal to the Environment
B Principal problem in disposal of organic
sludges is water. Twenty to fifty times
as much water as all other substances in
waste.
C Carbon and hydrogen in organic compounds
can be oxidized to CO_ and H„0 which do
not pollute the atmosphere. Avoid CO and
odor by proper furnace operation.
D Heat Production
1 Oxidation of 1 lb. of organic sludges is
sufficient to evaporate about 2 lb. of
water. Up to 3 lb. for oily sludge since
combined O as in carbohydrates reduces
heating value.
2 High temperature oxidation uses all the
heat of combustion to evaporate water
left in the sludge and usually requires
excess fuel.
3 Economics of incineration are therefore
closely tied to dewatering by sedimen-
tation, filtration, and drying.
E Treatment of wet sludge to aid further
processing.
1 Anaerobic digestion. Reduces solids
about 50% by hydrolysis and fermentation
to methane gas which is burned to CO_
and water. Produces foul supernatant
liquor which returns organics and
nutrients to the plant for recycle.
2 Sludge cooking at 370Q F. Porteous
Process improves filterability of solids.
Returns 10-20% of the BOD and 60-80%
of the nitrogen.
3 Wet oxidation - Zimpro at 350° F
removes 15% of COD by oxidation,
dissolves 25% of solids and 90% of
nitrogen. Higher temperatures destroy
more solids. Improves filtration,
produces a foul supernatant liquor.
4 Aerobic digestion Aerate for 1-30
days. Stabilizes solids, retains
nutrients but does not aid dewatering.
F Oxidation and dewatering on land surfaces.
An "old-fashioned" process.
1 Organics are oxidized by soil bacteria.
2 Nutrients and other pollutants are fixed
to a significant extent and kept out of
water supplies.
3 Must control putrefaction and spread
of pathogens by pretreatment.
Ill PHOSPHORUS
A Composition and Occurrence
1 Sewage contains orthophosphate,
polyphosphate and organic phosphates.
Total P in secondary effluent averages
near 8 mg/1 as P (24 as as
PgOj), large fluctuations with place
and time.
2 Biological treatment, which may begin
in the sewers, hydrolyzes about 90%
of the phosphates to ortho- as HPO^
in secondary effluent.
B Organic sludges carry a fraction of the
total P load.
1 Anaerobic digest;on normally returns
a large fraction of the P to the plant.
2 Combustion retains P in ash.
3 Land spreading fi^es P on soil minerals
but silt carries P into streams.
C Lime Sludges
1 High pH precipitates calcium phosphate
from secondary effluent as Ca,. OH
(P04)„, hydroxyapatite. This is
frequently referred to and calculated
as tri-calcium phosphate or "tri cal, "
Ca3(PO.)2, which is called bone
phosphate of lime, bpl, in Rock
Phosphate analyses.
2 Lime dosage of up to 600 mg/1 as
Ca(OH)2, (450 as CaO) has been used
to raise pH above 11 and precipitate
calcium phosphate.
38-2
-------
Ultimate Disposal to the Environment
3 Also precipitates alkalinity as CaCO^
and gelatinous Mg2 which traps
the turbidity, mostly organic.
4 Mg(OH>2 can be dissolved by CO
without significant loss of lime at
pH 9. 5. Slight excess of CC>2 may be
used to stabilize sludge against scale
formation.
5 Lime sludge can be dewatered easily
by sedimentation and vacuum filtration
or centrifugation to 25-40% solids.
6 Burning in a lime kiln or incinerator
converts CaCO^ to CaO. Calcium
phosphate is essentially unchanged.
7 CaO can be slaked to Ca(OH>2 which
can be reused. Calcium phosphate
remains with inerts including MgO
which does not slake.
8 High phosphate sludge has low solubility
in water and can be safely dumped.
May have market value as fertilizer
since P is available to growing plants.
9 Recovered lime costs nearly as much
as new lime but partially solves disposal
problem.
10 Lake Tahoe, California
D Alum Sludges
1 Aluminum salts hydrolyze to aluminum
hydroxide and precipitate phosphates.
2 Optimum pH near neutrality.
3 Either alum, A12(S04)„.XH„0, or
sodium aluminate, NaAKOH)^, can
be used with suitable pH adjustment.
4 Aluminum to phosphate ratio close to
2 1. A1P04.Al(OH>3 probably not a
pure compound.
5 Aluminum phosphate can be dissolved at
high pH (11-12) liberating aluminate
Al(OH)4~. If calcium is present calcium
phosphate will precipitate.
6 Reuse of aluminate requires acid to
bring down pH. May supply acid as
alum also providing makeup aluminum.
Some dragout of insoluble aluminum
precipitate expected.
7 Disposal of aluminum hydroxide sludges
rich in organic matter may be difficult.
Aluminum hydroxide clogs soil and
won't dewater unless frozen. Aluminum
phosphates are not dissolved in
anaerobic digesters.
E Iron Salts
1 Hydrolyze to produce ferric hydroxide
Fe(OH)g which removes phosphates as
basic ferric phosphate.
2 Ferric phosphate FePO^ reduced in
digesters to ferrous phosphate FegfPO^)^.
Insoluble but dissociated by HgS
to form FeS liberating soluble phosphates.
3 Possible utility when acid mine wastes
or iron pickle liquor is available. No
recovery.
IV NITROGEN
A All nitrogen comes from the air and
ultimately returns to the air.
1 All forms of N are biologically inter-
convertible. Report all forms of
nitrogen as mg/1 N.
2 All except N2 are pollutants. "Good"
fertilizers on the land but "bad"
fertilizers in water.
B Organic Nitrogen
1 Burn to N gas with some oxides of
nitrogen if furnace design is inadequate.
2 Hydrolyze to NH^ by anaerobic or short
time aerobic treatment.
3 Oxidize to nitrate with long time aeration
in presence of suitable bacteria.
38-3
-------
Ultimate Disposal to the Environment
C Ammonia
1 Pollutant above 1 mg/1 in municipal or
surface waters.
2 Chlorine destroys ammonia producing
N„ but requires 10 parts of Cl^ per
part of NH3 -N.
3 Ammonia present mostly as ammonium
ion below pH 9 mostly as dissolved NH3
above pH 10. Air strip with 300 cu ft.
air/gal. water at pH 10.8.
4 Lake Tahoe will combine lime
precipitation of phosphate at high pH
with air stripping of ammonia.
5 Battelle-Northwest is testing a zeolite
to concentrate ammonium in smaller
volume of water. This will reduce
size of air stripping tower. Air can
then be used in furnace where NH^
will burn to N^-
6 Soils adsorb NH4+. Bacteria in soil
convert excess to soluble nitrates.
Growing plants need NH^ or NO^ .
D Nitrates
1 PHS limit 10 mg/1 as N in drinking
water. Causes "blue babies".
2 Algal nutrient in surface waters and
source of dissolved oxygen in polluted
waters.
3 Denitrified by growing bacteria at low
oxygen levels supplying O2 and
liberating Ng. Demtrification occurs
in soils and can be done in packed beds
or tanks if food such as methanol is
supplied.
V SALTS IN SOLUTION
A Na+, K+, Ca**, Mg**, salts of CI , HC03 ,
S°4=
1 Soluble. No good precipitant.
2 No economical sale.
3 Illegal to discharge on surface in some
arid areas including Texas.
4 Solar evaporation to solid to reduce
transportation costs.
B Dilute in sea water or salt lakes.
1 Discharge to rivers on spring floods
has been practiced.
C Inject into underground cavities or saline
aquifers.
D Concentrated salts from Reverse Osmosis,
Electrodialysis, Ion Exchange.
1 Scale forming if concentrated 10-fold,
l. e., 90% water recovery.
VI TRACE ELEMENTS. POISONOUS IN
EXCESS
A Lime clarification will remove Ca, Mg,
Sr. Ba. Al, Cr 3, Mn, Fe 3, Co, Ni,
Cu by precipitation. May also remove
Zn, Cd, Hg, As, Sn, Sb, and Pb by
adsorption.
B Hg, Cd, and Zn strongly adsorbed on
organics but are volatile and may be lost
in flue gases.
C Borates--from peroxyborate bleaches in
heavy duty detergents and scouring
powders.
1 Not serious for drinking water.
2 Max. 0.5 mg/1 in irrigation water for
fruit trees and some other plants.
3 May need ion exchange resin specific
for borates.
D Chromates. Cr04~, Cr20? in acid
solution.
1 From cooling water treated to reduce
corrosion and from electroplating.
+3
2 Reduce to Cr with SOg and precipitate
as CrtOH)^.
38-4
-------
Ultimate Disposal to the Environment
E Cyanides. CN from electroplating.
1 Oxidize to COg, with CI
F Heavy Metals, Cyanides, Selenium,
Arsenic, and some other poisons can be
kept out of wastewater more economically
than they can be removed.
A portion of this material has been published
in the Proceedings Tenth Sanitary Engineering
Conference, Department of Civil Engineering,
University of Illinois, Edited by J. H. Austin
and Ursula Weise, May 1968.
This outline was prepared by Dr. Robert B.
Dean, Chief, Ultimate Disposal Research
Activities, Division of Research, Cincinnati
Water Research Laboratory, FWQA, SEC.
Revised, September 1968.
38-5
-------
CHLORINE DETERMINATIONS AND THEIR INTERPRETATION
I INTRODUCTION
Chlorine normally is applied to water as a
bactericidal agent, it reacts with water con-
taminants to form a variety of products con-
taining chlorine. The difference among
applied and residual chlorine represents the
chlorine demand of the water under conditions
specified. Wastewater chlorination is parti-
cularly difficult because the concentration of
organisms and components susceptible to
interaction with chlorine are high and variable.
Interferences with the chlorine determination
in wastewater confuse interpretation with
respect to the chlorine residual at a given
time and condition, its bactericidal potency,
or the future behavior.
II CHEMISTRY OF CHLORINATION
A Chlorine compounds (CI2) dissolve in water,
and hydrolyze immediately according to the
reaction.
Cl2 + H20 — HOC1 + H+ + Cl"
The products of this reaction are hypo-
chlorous and hydrochloric acid. The re-
action is reversible, but at pH values above
3. 0 and concentrations of chlorine below
1000 mg/1 the shift is predominantly to the
right leading to hypochlorous acid (HOCl).
Hypochlorous acid is a weak acid and con-
sequently ionizes in water according to the
equation
HOCl -r H+ + OCl"
This reaction is reversible. At a pH value
of 5. 0 or below almost all of the chlorine
is present as hypochlorous acid (HOCl)
whereas above pH 10.0 nearly all of it
exists as hypochlorite ion (OCl ). The pH
value that will control is the pH value
reached after the addition of chlorine.
Chlorine addition tends to lower the pH
and the addition of alkali hypochlorites
tends to raise the pH.
B The initial reactions on adding chlorine to
wastewaters may be assumed to be funda-
mentally the same as when chlorine is
added to water except for the additional
complications due to contaminants and
their concentration.
Hypochlorous acid (HOCl) reacts with
ammonia and with many other complex
derivatives of ammonia to produce com-
pounds known as chloramines. Formation
of the simple ammonia chloramines includes-
1 NH3 + HOCl — nh2C1 + H2°
monochloramme
2 NH2C1 + HOCl — NHC12 + H20
dichloramme
3 NH2C1 + NHC12 — N2 + 3 HC1
The distribution of the ammonia chloramines
is dependent on pH, as illustrated below
Percentage of Chlorine Present as
Monochloramme Dichloramme
5 16 84
6 38 62
7 65 35
8 85 15
9 94 6
PC. 11. 5.67
40-1
-------
Chlorine Determination and Their Interpretation
The formation of the ammonia chloramines
are dependent on pH, temperature, and
chlorine-ammonia ratio. Chlorine re-
actions with amino acids are likely, pro-
duct disinfecting powers are lower than
those of chlorine or of ammonia chloramines.
m TERMINOLOGY
A Terms used with Respect to Application
Site
1 Pre-chlorination - chlorine added
prior to any other treatment.
2 Post-chlorination - chlorine added
after other treatment.
3 Split chlorination - chlorine added at
different points in the plant - may in-
clude pre- and post -chlorination.
B Terms used in Designating Chlorine
Fractions
1 Free available residual chlorine - the
residual chlorine present as hypo-
chlorous acid and hypochlorite ion.
2 Combined available residual chlorine -
the residual chlorine present as chlor-
amines and organic chlorine containing
compounds.
3 Total available residual chlorine - the
free available residual chlorine + the
combined available residual chlorine -
may represent total amount of chlorine
residual present without regard to type.
In ordinary usage these terms are
shortened to free residual chlorine, com-
bined residual chlorine and total
residual chlorine. In the chlorination
of wastewaters only combined residual
chlorine is ordinarily present and is
often improperly termed chlorine
residual.
C Breakpoint chlorination specifically refers
to the ammonia-chlorine reaction where
applied chlorine hydrolyzes and reacts to
form chloramines and HC1 with the
chloramines eventually forming ^ + HC1
as in I. B. 3. Assuming no other chlorine
demand, the total chlorine residual will
rise, decrease to zero and rise again with
increasing increments of applied chlorine.
Other substances may produce humps in
the applied chlorine vs residual chlorine
plot due to oxidation of materials other
than ammonia. Sometimes these are
erroneously considered as a breakpoint.
IV ANALYTICAL METHODS
The o-Tolidine color test and Iodometric
titration methods are the basis for numerous
modifications for determining chlorine
residuals in water. The relative advantages
of a specific determination depends upon the
form in which the reactable chlorine exists
and the amount and nature of interferences
in the water.
Iodometric titration using the amperometric
endpomt appears to be the most accurate
residual chlorine method available (Standard
Methods APHA 12th Ed., p. 375, and ASTM
Standards, Part 23). The o-Tolidine and o-
Tolidme Arsenite methods require little
apparatus, and are readily adapted as a field
or control test. The Starch Iodine color
titration endpoint for iodometric titration
is suitable for use on clean water or stock
solutions and may be useful on certain types
of wastewater residuals. Selection of a suit-
able method of determining chlorine residuals
depends upon the correlation of the determined
residual and the bacterial kill in the presence
of existing interferences under applied
conditions.
A Iodometric Method
1 Scope and application
This method is applicable to the deter-
mination of total chlorine residual in
wastewaters, polluted waters and some
industrial wastewaters.
2 Summary of method
When a sample is treated with a measured
excess of standard phenylarseneoxide
40-2
-------
Chlorine Determination and Their Interpretation
solution, or a standard thiosulfate
solution, followed by the addition of
iodide, the iodine liberated at the
proper pH is stoichiometrically pro-
portional to the total chlorine present.
The liberated iodine reacts with the
phenylarseneoxide or thiosulfate before
any is lost to other extraneous reactions.
The excess phenylarseneoxide or thio-
sulfate is titrated with standard iodine
solution in the presence of starch until
the phenylarseneoxide or thiosulfate is
completely oxidized. The end-point of
the tiration is the next addition of
standard iodine solution that causes
a faint blue color to persist in the
sample.
3 Interferences
a Organic matter - reacts with liber-
ated iodine.
b Manganic manganese - liberates
iodine from iodide at pH 4.0.
c Ferric iron, ferncyanide and nitrites
up to 100 mg/1 do not interfere at a
pH of 4.0.
d Chromates - reduce phenylarseneoxide
or thiosulfate to an appreciable extent
before the excess can be titrated with
standard iodine.
e Excessive color and turbidity
B Iodometnc Method with Amperometnc
End-Point
1 Scope and application
This method is applicable to the deter-
mination of total chlorine residual in
wastewaters, polluted waters and some
industrial wastewaters. The back-
titration method is essential for waste-
waters in contrast to the direct titration
with phenylarseneoxide in clean waters.
2 Summary of method
When a sample is treated with a meas-
ured excess of standard phenylarsene-
oxide solution followed by the addition
of iodide, the iodine liberated at the
proper pH is stoichiometrically propor-
tional to the total chlorine present.
The iodine liberated reacts with the
phenylarseneoxide before any is lost to
other extraneous reactions. When the
cell is immersed in a sample so treated,
no current is generated due to halogens
nor is any further current generated,
as the excess phenylarseneoxide is
titrated with standard iodine solution
until the phenylarseneoxide is completely
oxidized. The end-point of the titration
is the next addition of standard iodine
solution that causes further current
to be generated and a microammeter
response or pointer deflection.
NOTE: As the end-point is approached
each increment of standard iodine solu-
tion causes a temporary deflection of the
microammeter, but the pointer drops
back to about its original position. The
true end-point is reached when a small
addition of standard iodine solution gives
a definite and permanent pointer deflection.
3 Interferences
a Organic matter - reacts with the
liberated iodine.
b Manganic manganese - liberates
iodine from iodide at a pH of 4. 0.
c Ferric iron, ferncyanide and
nitrites up to 100 mg/1 do not inter-
fere at a pH of 4.0.
d Chromates - reduces phenylarsene-
oxide to an appreciable extent before
the excess can be titrated with standard
iodine solution.
e Cupric ions may cause erratic be-
havior of the apparatus.
40-3
-------
Chlorine Determination and Their Interpretation
f Cuprous and silver ions tend to
poison the electrode.
C Orthotolidine Method
1 Scope and application
This method is applicable to the deter-
mination of total chlorine residual in
wastewaters, polluted waters and some
industrial wastewaters.
2 Summary of method
e Excessive color and turbidity.
D Orthotolidine- Arsenite Method
1 Scope and application
This method is applicable to the deter-
mination of free residue chlorine and
combined residual chlorine in waste-
waters, polluted waters and industrial
wastewaters, but as normally carried
out for wastewaters, etc, total residual
chlorine is measured.
When a sample is treated with a meas-
ured amount of orthotolidine reagent, the
orthotolidine is oxidized in the resulting
acid solution by chlorine and chloramines
and other oxidizing agents to produce a
yellow-colored compound (Holoquinone).
The color produced at pH values of less
than 1.8 is proportional to the amount
of chlorine present and is suitable for
quantitative measurement. The chlorine
residual in mg/1 is read directly from
the colored glass disks or sealed
colored liquid standards or is calculated
from a previously prepared standard
curve. NOTE Particular attention
is called to the importance of warming
the sample to 20°C after the addition
of orthotolidine reagent in order to
complete the reaction.
3 Interferences
a Organic matter - oxidizes orthotolidine
to produce a yellow color (Holo-
quinone) .
b Manganic manganese - in concentra-
tions above 0.01 mg/1 oxidizes
orthotolidine to produce a yellow
color (Holoquinone).
2 Summary of method
A sample is split into two fractions (a)
and (b). Sample (a) is treated with a
measured amount of arsenite reagent,
followed by the addition of orthotolidine
reagent. The arsenite reacts with
chlorine while orthotolidine reacts with
ferric iron, manganic manganese and
nitrite nitrogen to produce additional
color (represents interfering color).
Sample (b) is treated with a measured
amount of orthotolidine reagent. The
orthotolidine is oxidized in the resulting
acid solution by chlorine, chloramines
and other oxidizing agents to produce
a yellow-colored compound (Holoquinone)
as described in the orthotolidine method
(represents total amount of residual
chlorine present and interfering color).
Mg/1 total residual chlorine = b - a if
color compensation is not made directly.
NOTE, more accurate readings may be
obtained if cells containing sample
fractions (a) and (b) are placed in the
comparator in such relative positions
that color compensation is made
directly.
3 Interferences
c Ferric iron - in concentrations above a High color and turbidity
0. 3 mg/1 oxidizes orthotolidine to
produce a yellow color (Holoquinone).
V INTERPRETATION
d Nitrites - in concentrations above
0. 10 mg/1 of nitrite nitrogen oxidizes In general residual chlorine concentrations
orthotolidine to produce a yellow obtained by the lodometric titration method
color (Holoquinone). (starch iodide end-point and amperometric
I 40-4
i
I
-------
Chlorine Determination and Their Interpretation
end-point) will be higher than the concentrations
obtained from the orthotolidine and the orthoto-
lidine-arsenite methods. Some of the reasons
for the difference have been listed under the
individual methods. Extensive studies have
indicated that consistently better correlation
between bacterial kill and chlorine residual
found is possible when the titration method
is used.
REFERENCES
1 Standard Methods for the Examination of
Water and Wastewaters, 12th Ed.,
APHA, AWWA, WPCF. 1965.
2 1965 Book of ASTM Standards, Part 23 -
Industrial Water; Atmospheric Analysis.
American Society for Testing and
Materials. Philadelphia, Pa.
3 Sawyer, C.N. Chemistry for Sanitary
Engineers. McGraw-Hill Book Com-
pany, New York. 1960.
4 Moore, E. W. Fundamentals of Chlon-
nation of Sewage and Wastes. Water
and Sewage Works. Vol. 98, No. 3,
March 1951.
5 Day, R. V., Horchler, D. H., and Marks,
H. C. Residual Chlorine Methods and
Disinfection of Sewage. Industrial and
Engineering Chemistry, May 1953.
6 Marks, H. C., Joiner, R. R., and
Strandskov, F. B. Amperometnc
Titration of Residual Chlorine in
Sewage. Water and Sewage Works,
May 1948
This outline was prepared by J. L. Holdaway,
Chemist, Technical Program, Middle
Atlantic Region, FWPCA, 918 Emmet
Street, Charlottesville, VA 22901.
40-5
-------
WASTEWATER DISINFECTION
I INTRODUCTION
A In a recent survey of all municipal sewage
treatment plants, it was reported that an
overall 30% of treatment plants were
provided with facilities for introduction
of chlorine in connection with treatment
plant operations.
Briefly, the survey of treatment plants
utilizing chlorine may be summarized
in Table 1.
o
B In reviewing publications relating to the
use of chlorine with relation to wastewaters,
the uninitiated worker quickly can gain an
impression that chlorine is used in waste-
water treatment operations as an almost-
universal panacea, as a means of solving
whatever problems seem to be plaguing
the operations of the particular plant at
the time.
The purpose of this discussion is to
review the basic principles of
chlorination, and discuss its use for
wastewater disinfection.
II USEFUL PROPERTIES OF CHLORINE
In terms of its significance in wastewater
treatment processes, the important
properties of chlorine include the following
A Chlorine is a powerful oxidizing agent.
B Chlorine is poisonous to living organisms.
1 The poisonous properties of chlorine
probably are exerted through its
oxidizing ability, through which enzyme
systems essential to life are
irreversibly oxidized, or at least
are inactivated.
TABLE 1
Population served
Total number
of plants
Plants with
chlorination
Percentage with
chlorination
Less than 1, 000
2, 130
392
18
1, 000 to 5, 000
3, 468
921
27
5, 000 to 10, 000
863
340
39
10, 000 to 25, 000
595
292
49
25, 000 to 50, 000
199
127
64
50, 000 to 100, 000
99
54
55
More than 100, 000
164
90
61
SE. CL. 2.8.70
41-1
-------
Wastewater Disinfection
2 According to the category of organisms
for which chlorine is being used as a
poison, chlorine could be called a
germicide, a bactericide, a disinfecting
agent, an algicide, an ovocide, a
cysticide, or by any of several other
"-cide" terms.
C Chlorine is highly soluble in water, and
can be introduced economically into water
and wastewater with accuracy and with
adequate provision to protect the health
and safety of operational personnel and
the population which will be exposed to
contact with the chlorine-treated waters.
Different categories of organisms
differ widely in their susceptibility to
chlorine. Figure 1 illustrates the
relative susceptibility of Escherichia
coli and three different kinds of
viruses, to hypochlorous acid. Note
that those relationships are attributable
to a "free" chlorine residual and a
"pure" culture. This is not in a
wastewater.
The rate at which the disinfecting
(killing) process takes place is variable,
and subject to control through manage-
ment of such interrelated factors as
temperature, concentration, pH, and
the amount, kind, and physical state
of other suspended and dissolved sub-
stances present in the water.
Ill TERMINOLOGY
A Terms used with respect to application
site
1 Pre-chlorination - chlorine added
prior to any other treatment
2 Post-chlorination - chlorine added
after other treatment
3 Split chlorination - chlorine added at
different points in the plant - may
include pre- and post-chlorination
B Terms used in defining chlorine residuals
1 Chlorine dosage is the amount of
chlorine added to a water or waste-
water at the point of injection.
i o
E l\l II I l\l I I NJ I 1 IMII=
\ z
\
\ -
\-
¦»>
COXSACKIf
POLIOVIRUS
E COLI
ADENOVIRUS 3
I 2 3 4 5 6 8 1 0 2 3 4 5 6 8 10
3040 80100
RELATIONSHIP BETWEEN CONCENTRATION AND TIME FOR 99% DESTRUCTION
OF J_ C0LI_ AND 3 VIRUSES BY HYPOCHLOROUS ACID |H0CI] AT 0 E°C
FIGURE 1
41-2
-------
Wastewater Disinfection
2 Chlorine demand is the amount of the
chlorine dosage which is utilized to
oxidize or combine with organic or
inorganic substances present, and
results in a chlorine compound which
is of no value for disinfection.
3 Residual chlorine is the amount of
chlorine remaining after the chlorine
demand has been satisfied,
chlorine dosage - chlorine demand 3
chlorine residual.
4 Free available residual chlorine - the
residual chlorine present as
hypochlorous acid and hypochlorite ion.
5 Combined available residual chlorine -
the residual chlorine present as
chloramines.
6 Total available residual chlorine - the
free available residual chlorine + the
combined available residual - may
represent total amount of chlorine
residual present without regard to type.
In ordinary usage these terms are
shortened to free residual chlorine,
combined residual chlorine and total
residual chlorine.
In the chlorination of wastewaters only
combined residual chlorine is ordinarily
present and is often improperly termed
chlorine residual.
C Breakpoint chlorination specifically refers
to the ammonia-chlorine reaction where
applied chlorine hydrolyzes and reacts to
form chloramines and HC1 with the
chloramines eventually forming ^ + HC1.
Assuming no other chlorine demand, the
total chlorine residual will rise, decrease
to zero and rise again with increasing
increments of applied chlorine. Other
substances may produce humps in the
applied chlorine vs residual chlorine plot
due to oxidation of materials other than
ammonia. Sometimes these are erroneously
considered as a breakpoint.
IV CHEMISTRY OF CHLORINATION
A Most commonly, chlorine is added to
water in solution, being kept in tanks in
liquid form under pressure, the liquid
chlorine is converted to gas which in turn
is dissolved into the water or wastewater
being treated.
Chlorine gas (Clg) dissolves in water, and
hydrolyzes immediately according to the
reaction.
Cl2 + HzO "Z HOC1 = H+ + Cl"
The products of this reaction are
hypochlorous and hydrochloric acid.
The reaction is reversible, but at pH
value s above 3. 0 and concentrations of
chlorine below 1000 mg/1 the shift is
predominantly to the right leading to
hypochlorous acid (HOC1).
Hypochlorous acid is a weak acid and
consequently ionizes in water according
to the equation:
HOC1 ^ H+ + OCl"
This reaction is reversible. At a pH
value of 5. 0 or below almost all of the
chlorine is present as hypochlorous acid
(HOC1) whereas above pH 10. 0 nearly all
of it exists as hypochlorite ion {OCl ).
The pH value that will control is the pH
value reached after the addition of chlorine.
Chlorine addition tends to lower the pH
and the addition of alkali hypochlorites
tends to raise the pH.
B The initial reactions on adding chlorine
to wastewaters may be assumed to be
fundamentally the same as when chlorine
is added to water except for the additional
complications due to contaminants and
their concentration.
41-3
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Wastewater Disinfection
Hypochlorous acid (HOC1) reacts with
ammonia and with many other complex
derivatives of ammonia to produce
compounds known as chloramines.
Formation of the simple ammonia
chloramines includes-
1 NH + HOC1 — NH CI + HO
<3 1 2
monochloramine
2 NHgCl + HOC1—~ NHC12 + H20
dichloramine
3 NHC1 + HOC1 —~ NC1„ + HO
& 3 2
trichloramine
4 NHgCl + NHC12 — N + 3HC1
Chloramines are formed in water con-
taining ammonia, when chlorine is added,
a mixture of monochloramine (NH CI),
and dichloramine (NHClg), are formed.
If enough chlorine is added to react with
&11 the available NH„ and still leave an
excess of chlorine, then nitrogen
trichloride (NClg) may be formed.
Chloramines are less reactive chemically
and less effective as germicides, than
are the free forms of chlorine.
The distribution of the ammonia chloramines
is dependent on pH, as illustrated below-
TABLE 2
Percentage of Chlorine Present as
pH Monochloramine Dichloramine
5
16
84
6
38
62
7
65
35
8
85
15
9
94
6
The formation of the ammonia chloramines
is also dependent on temperature, and
chlorine-ammonia ratio. Chlorine
reactions with amino acids are also likely.
product disinfecting powers are lower
than those of chlorine or of ammonia
chloramines.
V DISINFECTION OF WASTEWATERS
A Sewage is known to contain tremendous
numbers of microorganism of intestinal
origin. Individuals harboring pathogenic
organisms including bacteria viruses
protozoa and other forms of disease
producing organisms are likely in any
population. Discharges from infected
persons constitute a hazard to the health
and safety of individual coming into
contact with such sewage or treatment
plant effluents unless disinfected.
1 In recent years, an epidemic of infectious
hepatitis was traced to shellfish harvested
from polluted waters in Raritan Bay A
pollution study of some magnitude was
initiated, and considerable numbers
of bacteria attributable to waste treat-
ment plants adjoining Raritan Bay
were demonstrated in the study. During
the period when wastewater treatment
plants chlorinated the treatment plant
effluents, enteric pathogenic bacteria
could not be recovered. However,
when chlorination of treatment plant
effluents was discontinued. Salmonella
were discovered with some regularity
at sampling points related to the above
waste treatment plant discharges.
2 In studies of the Red River of the North,
Salmonella has been discovered with
great regularity in waters polluted
through discharge of inadequately
treated wastewaters. In some cases.
Salmonella has been discovered where
the fecal coliform count was only a few
hundreds per 100 ml.
B Objective
Many people feel that we should base
chlorination levels on the presence of,
or number of actual pathogenic organisms
present, but as yet this is neither feasible
nor warranted, and we still use the
coliform indicator organisms. The
density of these m wastewaters vary
41-4
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Wastewater Disinfection
greatly, and if positive information is
desired must be determined for each
plant. Table 3 shows some typical
residential densities.
TABL*E 3
BACTERIAL DENSITIES IN VARIOUS SEWAGES
Bacterial Densities, Count/100 ml
Sewage
Total
Coliform
Fecal
Coliform
Fecal
Streptococci
Ratio
FC/FS
Residential
"A"
17, 200, 000
17, 200, 000
4, 000, 000
4.3
Residential
"B"
33, 000, 000
10, 900, 000
2, 470, 000
4.4
Residential
"c"
1,940, 000
340,000
64, 000
5.3
Residential
"D"
6,300, 000
1, 720, 000
200, 000
8.6
C Chlorination Efficiency
Chlorine functions as a disinfectant in the
sense that it is applied in dosages con-
sidered sufficient to destroy the pathogenic
(disease-causing) organisms. Disinfection
is not construed to mean total destruction
of all living organisms present in the
sewage effluents (sterilization).
For disinfection, chlorine must be added
in sufficient concentration, and with a
sufficient contact time, to ensure
destruction of the pathogenic bacteria.
However, this inactivation is evaluated
by coliform inactivation.
1 Much outdated information is available
regarding the efficiency of chlorine in
wastewaters, and certain literature
claims chlorine efficiencies equal to
or greater than the efficiencies in clean
water. One basis of chlorine application
for disinfection, widely noted in test-
books of sanitary engineering practices,
provides recommendations for adequate
disinfection by adding chlorine in an
amount sufficient to kill 99. 9% of all
coliform bacteria in the sewage, or
sewage effluent, after a contact time
of 15 minutes, and to have a chlorine
residual of 0. 5 mg/liter (according to
one recommendation, the residual
chlorine should be 2 mg/liter). A
widely-quoted table of chlorine
application follows in Table 4.
2 The efficiency of chlorine as a
disinfectant is affected by pH,
temperature, contact time, con-
centration, solids present, and a
number of other variables. The
attached Figure 2 shows some
excellent data regarding efficiency
of chlorine in clear water. Obviously
chlorine will not be equally/nor more
effective in wastewater. By looking at
the attached Figure 3 you can see this
is true.
The data in Figure 3 has also been
essentially verified by other
investigators. Based upon what we
know of chlorination in water, these
data appear quite reasonable.
41-5
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Wastewater Disinfection
TABLE 4
Amounts of Chlorine required for Disinfection of Sewage and Sewage Effluents with
Chlorine Residual 0. 5 mg/liter after Contact Time of 15 Minutes
Type of Sewage or Effluent
Probable Chlorine
Requirements
Chlorinator Capacities*
mg/liter
lb/day/1000
persons
mg/liter
lb/day/1000
persons
Raw sewage, depending on strength
and staleness
6-25
5-21
30
25
Settled Sewage
5-20
4-17
25
20
Chemically precipitated sewage
3-20
3-17
25
20
Trickling filter effluent
3-20
3-17
25
20
Activated sludge effluent
2-20
2-17
25
20
Intermittent sand filter effluent
1-10
1- 3
15
12
*For sewage flow of 100 gallons per capita per day.
VI CONCLUSION*
It is not the purpose of this discussion to
recommend chlorine dosages applicable to
various types of waste treatment operations.
Chlorine dosage standards are the prerog-
ative of the various regulatory agencies.
The main objective here is to provide a basic
understanding of some of the important
factors that affect the efficiency of chlorination
in controlling bacteria and viruses in sewage
effluents. Research data and examples from
practical operation, along with reference
material in the literature, have been com-
bined here to provide a starting base. This
information should be evaluated for its
relevance to specific plant situations and,
where appropriate and pertinent, can then be
used to provide guidelines for practical
disinfection applications m the plant.
It is emphasized that chlormation of sewage
effluents is a vastly more complex and
unpredictable operation than chlorination of
water supplies. It is extremely difficult to
maintain a high, uniform, and predictable
level of disinfecting efficiency m any but the
most efficiently operated waste treatment
plants. One should strive for the maximum
level of oxidation attainable because a
*C.W. Chambers
completely oxidized and highly clarified
effluent is easy to disinfect. On the basis
of information presented in this discussion,
along with that obtained by the author in the
laboratory investigation of germicides, it is
concluded that the following general guide-
lines are applicable in varying degree to the
practical disinfection of sewage treatment
plant effluents with chlorine.
1 The coliform test is the primary
standard for determining the bacteri-
ological quality of water and should be
similarly used for evaluating the
disinfecting effectiveness of chlorination
in sewage effluents.
2 While amy of the standard chlorine
residual tests may be used, the
amperometric test is the most reliable.
3 The disinfecting action of free available
chlorine (hypochlorous acid) is much
more potent than that of monochloramine.
4 The effects of pH and temperature
should be considered. Alkaline wastes
are more difficult to disinfect,
especially during periods of low
temperature.
41-6
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Wastewater Disinfection
MINIMUM
30 MINUTE CHLORINE RESIDUALS
. FOR NATURALLY CLEAR OR FILTERED WATERS
APPROVED BY THE COMMITTEE ON SANITARY ENGINEERING AND ENVIRONMENT
National Academy of Sciences, National Research Council
Consumption of waters containing high
chlorine residuals is not likely to be>
tolerated their use without adequate J,
dechlorination is not recommended J .
E
100
UJ
UJ
>—
MINIMUM RECOMMENDED RESIDUAL
«/>
0.01
11.0
HYDROGEN ION CONCENTRATION
FIGURE 2
National Academy of Sciences, National Research Council
-------
Wastewater Disinfection
100
5 Min.
5 Mm
15 M in
30 Mm.
60 Mm
120 Mm.
30 Min
C0LIF0RMS
T2 BACTERIOPHAGE
X
1
0 0 5 1 0 15
AMPEROMETRIC RESIDUAL, mg/l
Percent conforms and 12 bacteriophage remaining vs ampherometric residual
after different detention times in trickling filter effluent.
Burns and Sproul (16) Courtesy Journal Water Pollution Control Federation
2 0
FIGURE 3
41-8
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Wastewater Disinfection
5 For practical planning purposes, the
disinfecting effect of residual chlorine
can be assumed to be monochloramine
or less germicidal forms.
6 Chlorine dosage is a less significant
factor than contact time but either, if
excessively increased, will reach a
point of diminishing returns.
7 Flow in sewage lines should be main-
tained at maximum practical levels to
assure the freshest influent possible.
Septic sewage is high in ammonia and
sulfides and therefore very difficult and
expensive to disinfect.
8 Caution should be exercised in returning
digester supernatant liquor to the
primary tank influent, otherwise, high
chlorine demands may occur and pro-
duce an effluent that is difficult to
disinfect.
9 Where possible, chlorine demand
schedules should be developed in order
that chlorine feed rates may be adjusted
to the varying requirements necessary
to yield the desired coliform reduction.
10 Two-stage chlorination is more effective
for disinfection than single-stage
application.
11 Good mixing of chlorine with the effluent
is essential to consistently produce an
effluent of uniform coliform content.
12 Settled primary effluents are more
difficult to chlorinate to a specified
coliform content than secondary effluents,
and those from well-operated, more
advanced waste treatment plants are
relatively easy to disinfect.
13 Each plant must develop its own data for
correlating chlorine dosage, residual,
and holding time to yield predictably the
desired reduction in coliform content.
In view of the present limited efforts to
evaluate the effectiveness of chlorination in
terms of the bacterial quality of effluents
discharged, I would again quote for your
serious consideration today a guideline
offered by Chamberlin (37) more than 20
years ago. Concerning the use of chlorine,
he said "... .the best advice. . .. is to
chlorinate intelligently, but not blindly. "
This outline was prepared by D. J. Hernandez,
Sanitary Engineer, PNWL, FWQA,
Corvallis, OR,
41-9
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METHODS WHICH MAY BE USED TO DETECT
INDUSTRIAL WASTE PROBLEMS
I Prepare, adopt and enforce a sewer
ordinance that will regulate the use and
discharge of wastes into the public sewer
system. (See model sewer ordinance).
A model sewer ordinance can be obtained
from the Water Pollution Control Federation
and can be readily adapted to fit the individual
need.
II Develop an industrial waste inventory of
all industries that are connected to the sewer
system.
A Name and address of the company.
B Name, address, and telephone number of
person in responsible charge.
C Nature of manufacturing process, 1. e.,
what do they produce or process.
D Nature and quantity of wastes to be discharged.
Ill Pretreatment of industrial wastes may be
necessary to meet the conditions set forth in
the ordinance. Pretreatment may require one
or more of the following:
A Screening to remove solids that could
interfere with the treatment process.
B Settling to remove settleable solids and
sludge or mud before discharge to the
sewer.
C Neutralizing to adjust the pH to acceptable
limits.
D Aerating to restore dissolved oxygen.
E Coagulating with chemicals or air to
remove grease, oil or toxic materials.
F Skimming to control floating material.
IV Tracing of oil and other petroleum wastes
can often be accomplished by anchoring small
blocks of painted wood in manholes where
they will become coated with oil or grease.
By a process of elimination, the source can
be pinpointed. Other items that can be used
are
A Recording pH and D. O. meters that will
record any significant change in the waste
with respect to pH and D.O.
B Automatic samplers that will composite
a representative sample of the waste over
a given period of time. Laboratory
analyses may reveal a specific component
that can be traced to its origin.
C Portable flow recorder that can be installed
in manholes to measure the sewage flow
from a given area.
This outline was prepared by Edgar R. Lynd,
Municipal Waste Treatment Program,
Oregon State Sanitary Authority, Portland,
Oregon.
SE. MAN. 6. 11.68
42-1
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THE MODEL SEWER ORDINANCE
AN ORDINANCE REGULATING THE USE OF PUBLIC AND PRIVATE SEWERS AND
DRAINS, PRIVATE SEWAGE DISPOSAL, THE INSTALLATION AND CONNECTION OF
BUILDING SEWERS, AND THE DISCHARGE OF WATERS AND WASTES INTO THE PUBLIC
SEWER SYSTEM (S): AND PROVIDING PENALTIES FOR VIOLATIONS THEREOF- IN THE
CITY OF , COUNTY OF , STATE
OF .
Be it ordained and enacted by the Council of the City of
State of as follows-
ARTICLE I
Definitions
Unless the context specifically indicates otherwise, the meaning of terms used m this
ordinance shall be as follows.
Sec. 1. "BOD" (denoting Biochemical Oxygen Demand) shall mean the quantity of oxygen
utilized in the biochemical oxidation of organic matter under standard laboratory
procedure in five (5) days at 20° C, expressed in milligrams per liter.
Sec. 2. "Building Drain" shall mean that part of the lowest horizontal piping of a drainage
system which receives the discharge from soil, waste, and other drainage pipes inside
the walls of the building and conveys it to the building sewer, beginning five (5) feet
(1.5 meters) outside the inner face of the building wall.
Sec. 3. "Building Sewer" shall mean the extension from the building drain to the public
sewer or other place of disposal.
Sec. 4. "Combined Sewer" shall mean a sewer receiving both surface runoff and sewage.
Sec. 5. "Garbage" shall mean solid wastes from the domestic and commercial preparation,
cooking, and dispensing of food, and from the handling, storage, and sale of produce.
Sec. 6. "Industrial Wastes" shall mean the liquid wastes from industrial manufacturing
processes, trade, or business as distinct from sanitary sewage.
Sec. 7. "Natural Outlet" shall mean any outlet into a watercourse, pond, ditch, lake, or
other body of surface or ground water.
Sec. 8. "Person" shall mean any individual, firm, company, association, society,
corporation, or group.
Sec. 9. "pH" shall mean the logarithm of the reciprocal of the weight of hydrogen ions
in grams per liter of solution.
SE. MAN. 7. 11.68
43-1
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The Model Sewer Ordinance
Sec. 10. "Properly Shredded Garbage" shall mean the wastes from the preparation,
cooking, and dispensing of food that have been shredded to such a degree that all
particles will be carried freely under the flow conditions normally prevailing in
public sewers, with no particle greater than one-half (1/2) inch (1.27 centimeters)
in any dimension.
Sec. 11. "Public Sewer" shall mean a sewer in which all owners of abutting properties
have equal rights, and is controlled by public authority.
Sec. 12. "Sanitary Sewer" shall mean a sewer which carries sewage and to which storm,
surface, and groundwaters are not intentionally admitted.
Sec. 13. "Sewage" shall mean a combination of the water-carried wastes from residences,
business buildings, institutions, and industrial establishments, together with such
ground, surface, and stormwaters as may be present.
Sec. 14. "Sewage Treatment Plant" shall mean any arrangement of devices and structures
used for treating sewage.
Sec. 15. "Sewage Works" shall mean all facilities for collecting, pumping, treating, and
disposing of sewage.
Sec. 16. "Sewer" shall mean a pipe or conduit for carrymg sewage.
Sec. 17. "Shall" is mandatory, "May" is permissive.
Sec. 18. "Slug" shall mean any discharge of water, sewage, or industrial waste which in
concentration of any given constituent or in quantity of flow exceeds for any period of
duration longer than fifteen (15) minutes more than five (5) times the average twenty-
four (24) hour concentration or flows during normal operation.
Sec. 19. "Storm Drain" (sometimes termed "storm sewer")shall mean a sewer which
carries storm and surface waters and drainage, but excludes sewage and industrial
wastes, other than unpolluted cooling water.
Sec. 20. "Superintendent" shall mean the (Superintendent of Sewage Works and/or of
Water Pollution Control) of the (city) of ( ), or his authorized deputy, agent,
or representative.
Sec. 21. "Suspended Solids" shall mean solids that either float on the surface of, or are
in suspension in water, sewage, or other liquids, and which are removable by
laboratory filtering.
Sec. 22. "Watercourse" shall mean a channel in which a flow of water occurs, either
continuously or intermittently.
Sec. 23. "Hearing Board" shall mean that Board appointed according to provision of
Article ( ). (This section to be included only if optional article entitled "Hearing
Boards" is made a part of the ordinance. )
43-2
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The Model Sewer Ordinance
ARTICLE II
Use of Public Sewers Required
Sec. 1. It shall be unlawful for any person to place, deposit, or permit to be deposited
in any unsanitary manner on public or private property within the (city) of ( ), or
in any area under the jurisdiction of said (city), any human or animal excrement,
garbage, or other objectionable waste.
Sec. 2. It shall be unlawful to discharge to any natural outlet within the (city) of ( ),
or in any area under the jurisdiction of said (city), any sewage or other polluted
waters, except where suitable treatment has been provided in accordance with sub-
sequent provisions of this ordinance.
Sec. 3. Except as hereinafter provided, it shall be unlawful to construct or maintain any
privy, privy vault, septic tank, cesspool, or other facility intended or used for the
disposal of sewage.
Sec. 4. The owner of all houses, buildings, or properties used for human occupancy,
employment, recreation, or other purposes, situated within the (city) and abutting
on any street, alley, or right-of-way in which there is now located or may in the
future be located a public sanitary or combined sewer of the (city), is hereby required
at his expense to install suitable toilet facilities therein, and to connect such facilities
directly with the proper public sewer in accordance with the provisions of this ordinance,
within (ninety (90) days) after date of official notice to do so, provided that said public
sewer is within (one hundred (100) feet (30.5 meters)) of the property line.
ARTICLE III
Private Sewage Disposal
Sec. 1. Where a public sanitary or combined sewer is not available under the provisions
of Article II, Section 4, the building sewer shall be connected to a private sewage
disposal system complying with the provisions of this article.
Sec. 2. Before commencement of construction of a private sewage disposal system the
owner shall first obtain a written permit signed by the (Superintendent). The application
for such permit shall be made on a form furnished by the (city), which the applicant
shall supplement by any plans, specifications, and other information as are deemed
necessary by the (Superintendent). A permit and inspection fee of ( ) dollars shall
be paid to the (city) at the time the application is filed.
Sec. 3. A permit for a private sewage disposal system shall not become effective until
the installation is completed to the satisfaction of the (Superintendent). He shall be
allowed to inspect the work at any stage of construction and, in any event, the applicant
for the permit shall notify the (Superintendent) when the work is ready for final
inspection, and before any underground portions are covered. The inspection shall be
made within ( ) hours of the receipt of notice by the (Superintendent).
43-3
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The Model Sewer Ordinance
Sec. 4. The type, capacities, location, and layout of a private sewage disposal system
shall comply with all recommendations of the Department of Public Health of the
State of ( ). No permit shall be issued for any private sewage disposal system
employing subsurface soil absorption facilities where the area of the lot is less than
( ) square feet (square meters). No septic tank or cesspool shall be permitted
to discharge to any natural outlet.
Sec. 5. At such time as a public sewer becomes available to a property served by a
private sewage disposal system, as provided in Article III, Section 4, a direct
connection shall be made to the public sewer in compliance with this ordinance, and
any septic tanks, cesspools, and similar private sewage disposal facilities shall be
abandoned and filled with suitable material.
Sec. 6. The owner shall operate and maintain the private sewage disposal facilities in a
sanitary manner at all times, at no expense to the (city).
Sec. 7. No statement contained in this article shall be construed to interfere with any
additional requirements that may be imposed by the Health Officer.
Sec. 8. When a public sewer becomes available, the building sewer shall be connected
to said sewer within sixty (60) days and the private sewage disposal system shall be
cleaned of sludge and filled with clean bank-run gravel or dirt.
ARTICLE IV
Building Sewers and Connections
Sec. 1. No unauthorized person shall uncover, make any connections with or opening
into, use, alter, or disturb any public sewer or appurtenance thereof without first
obtaining a written permit from the (Superintendent).
Sec. 2. There shall be two (2) classes of building sewer permits (a) for residential and
commercial service, and (b) for service to establishments producing industrial wastes.
In either case, the owner or his agent shall make application on a special form furnished
by the (city). The permit application shall be supplemented by any plans, specifications,
or other information considered pertinent in the judgment of the (Superintendent). A
permit and inspection fee of ( ) dollars for a residential or commercial building
sewer permit and ( ) dollars for an industrial building sewer permit shall be paid
to the (city) at the time the application is filed.
Sec. 3. All costs and expense incident to the installation and connection of the building
sewer shall be borne by the owner. The owner shall indemnify the (city) from any
loss or damage that may directly or indirectly be occasioned by the installation of the
building sewer.
Sec. 4. A separate and independent building sewer shall be provided for every building;
except where one building stands at the rear of another on an interior lot and no
private sewer is available or can be constructed to the rear building through an adjoining
alley, court, yard, or driveway, the building sewer from the front building may be
extended to the rear building and the whole considered as one building sewer.
43-4
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The Model Sewer Ordinance
Sec. 5. Old building sewers may be used in connection with new buildings only when they
are found, on examination and test by the (Superintendent), to meet all requirements
of this ordinance.
Sec. 6. The size, slope, alignment, materials of construction of a building sewer, and
the methods to be used in excavating, placing of the pipe, jointing, testing, and back-
filling the trench, shall all conform to the requirements of the building and plumbing
code or other applicable rules and regulations of the (city). In the absence of code
provisions or in amplification thereof, the materials and procedures set forth in
appropriate specifications of the A. S. T. M. and W. P. C. F. Manual of Practice No. 9
shall apply.
Sec. 7. Whenever possible, the building sewer shall be brought to the building at an
elevation below the basement floor. In all buildings in which any building drain is
too low to permit gravity flow to the public sewer, sanitary sewage carried by such
building drain shall be lifted by an approved means and discharged to the building sewer.
Sec. 8. No person shall make connection of roof downspouts, exterior foundation drains,
areaway drains, or other sources of surface runoff or groundwater to a building sewer
or building drain which in turn is connected directly or indirectly to a public sanitary
sewer.
Sec. 9. The connection of the building sewer into the public sewer shall conform to the
requirements of the building and plumbing code or other applicable rules and regulations
of the (city), or the procedures set forth in appropriate specifications of the A.S. T. M.
and the W. P. C. F. Manual of Practice No. 9. All such connections shall be made
gastight and watertight. Any deviation from the prescribed procedures and materials
must be approved by the (Superintendent)before installation.
Sec. 10. The applicant for the building sewer permit shall notify the (Superintendent) when
the building sewer is ready for inspection and connection to the public sewer. The
connection shall be made under the supervision of the (Superintendent) or his
representative.
Sec. 11. All excavations for building sewer installation shall be adequately guarded with
barricades and lights so as to protect the public from hazard. Streets, sidewalks,
parkways, and other public property disturbed in the course of the work shall be
restored in a manner satisfactory to the (city).
ARTICLE V
Use of the Public Sewers
Sec. 1. No person shall discharge or cause to be discharged any stormwater, surface
water, ground water, roof runoff, subsurface drainage, uncontaminated cooling water,
or unpolluted industrial process waters to any sanitary sewer.
Sec. 2. Stormwater and all other unpolluted drainage shall be discharged to such sewers
as are specifically designated as combined sewers or storm sewers, or to a natural
outlet approved by the (Superintendent). Industrial cooling water or unpolluted process
waters may be discharged, on approval of the (Superintendent), to a storm sewer,
combined sewer, or natural outlet.
43-5
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The Model Sewer Ordinance
Sec. 3. No person shall discharge or cause to be discharged any of the following
described waters or wastes to any public sewers.
(a) Any gasoline, benzene, naphtha, fuel oil, or other flammable or explosive liquid,
solid, or gas.
(b) Any waters or wastes containing toxic or poisonous solids, liquids, or gases in
sufficient quantity, either singly or by interaction with other wastes to injure or
interfere with any sewage treatment process, constitute a hazard to humans or
animals, create a public nuisance, or create any hazard in the receiving waters
of the sewage treatment plant, including but not limited to cyanides in excess of
two (2) mg/1 as CN in the wastes as discharged to the public sewer.
(c) Any waters or wastes having a pH lower than (5.5), or having any other corrosive
property capable of causing damage or hazard to structures, equipment, and
personnel of the sewage works.
(d) Solid or viscous substances in quantities or of such size capable of causing
obstruction to the flow in sewers, or other interference with the proper operation
of the sewage works such as, but not limited to, ashes, cinders, sand, mud,
straw, shavings, metal, glass, rags, feathers, tar, plastics, wood, unground
garbage, whole blood, paunch manure, hair and fleshings, entrails and paper
dishes, cups, milk containers, etc. either whole or ground by garbage grinders.
Sec. 4. No person shall discharge or cause to be discharged the following described
substances, materials, waters, or wastes if it appears likely in the opinion of the
(Superintendent) that such wastes can harm either the sewers, sewage treatment process,
or equipment, have an adverse effect on the receiving stream, or can otherwise endanger
life, limb, public property, or constitute a nuisance. In forming his opinion as to the
acceptability of these wastes, the (Superintendent) will give consideration to such factors
as to quantities of subject wastes in relation to flows and velocities in the sewers,
materials of construction of the sewers, nature of the sewage treatment process,
capacity of the sewage treatment plant, degree of treatability of wastes in the sewage
treatment plant, and other pertinent factors. The substances prohibited are:
(a) Any liquid or vapor having a temperature higher than one hundred fifty (150)of
(65° C).
(b) Any water or waste containing fats, was, grease, or oils, whether emulsified or
not, in excess of one hundred (100) mg/1 or containing substances which may
solidify or become viscous at temperatures between thirty-two (32) and one hundred
fifty (150)o F (0 and 65Q C).
(c) Any garbage that has not been properly shredded. The installation and operation
of any garbage grinder equipped with a motor of three-fourths (3/4) horsepower
(0. 76 hp metric) or greater shall be subject to the review and approval of the
(Superintendent).
(d) Any waters or wastes containing strong acid iron pickling wastes, or concentrated
plating solutions whether neutralized or not.
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The Model Sewer Ordinance
(e) Any waters or wastes containing iron, chromium, copper, zinc, and similar
objectionable or toxic substances, or wastes exerting an excessive chlorine
requirement, to such degree that any such material received in the composite
sewage at the sewage treatment works exceeds the limits established by the
(Superintendent) for such materials.
(f) Any waters or wastes containing phenols or other taste- or odor-producing
substances, in such concentrations exceeding limits which may be established
by the (Superintendent) as necessary, after treatment of the composite sewage,
to meet the requirements of the State, Federal, or other public agencies of
jurisdiction for such discharge to the receiving waters.
(g) Any radioactive wastes or isotopes of such half-life or concentration as may
exceed limits established by the (Superintendent) in compliance with applicable
State or Federal regulations.
(h) Any waters or wastes having a pH in excess of (9. 5).
(1) Materials which exert or cause-
(1) Unusual concentrations of inert suspended solids (such as, but not limited
to. Fullers earth, lime slurries, and lime residues) or of dissolved solids
(such as, but not limited to, sodium chloride and sodium sulfate).
(2) Excessive discoloration (such as, but not limited to, dye wastes and
vegetable tanning solutions).
(3) Unusual BOD, chemical oxygen demand, or chlorine requirements in
such quantities as to constitute a significant load on the sewage treatment
works.
(4) Unusual volume of flow or concentration of wastes constituting "slugs" as
defined herein.
(j) Waters or wastes containing substances which are not amenable to treatment
or reduction by the sewage treatment processes employed, or are amenable to
treatment only to such degree that the sewage treatment plant effluent cannot
meet the requirements of other agencies having jurisdiction over, discharge to
the receiving waters.
Sec. 5. If any waters or wastes are discharged, or are proposed to be discharged to
the public sewers, which waters contain the substances or possess the characteristics
enumerated in Section 4 of this Article, and which in the judgment of the (Superintendent),
may have a deleterious effect upon the sewage works, processes, equipment, or
receiving waters, or which otherwise create a hazard to life or constitute a public
nuisance, the (Superintendent) may;
(a) Reject the wastes,
(b) Require pretreatment to an acceptable condition for discharge to the public sewers,
(c) Require control over the quantities and rates of discharge, and/or
43-7
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The Model Sewer Ordinance
(d) Require payment to cover the added cost of handling and treating the wastes not
covered by existing taxes or sewer charges under the provisions of Section 10
of this article.
If the (Superintendent) permits the pretreatment or equalization of waste flows, the
design and installation of the plants and equipment shall be subject to the review and
approval of the (Superintendent), and subject to the requirements of all applicable
codes, ordinances, and laws.
Sec. 6. Grease, oil, and sand interceptors shall be provided when, in the opinion of
the (Superintendent), they are necessary for the proper handling of liquid wastes
containing grease in excessive amounts, or any flammable wastes, sand, or other
harmful ingredients* except that such interceptors shall not be required for private
living quarters or dwelling units. All interceptors shall be of a type and capacity
approved by the (Superintendent), and shall be located as to be readily and easily
accessible for cleaning and inspection.
Sec. 7. Where preliminary treatment or flow-equalizing facilities are provided for
any waters or wastes, they shall be maintained continuously in satisfactory and
effective operation by the owner at his expense.
Sec. 8. When required by the (Superintendent), the owner of any property serviced by
a building sewer carrying industrial wastes shall install a suitable control manhole
together with such necessary meters and other appurtenances in the building sewer
to facilitate observation, sampling, and measurement of the wastes. Such manhole,
when required, shall be accessibly and safely located, and shall be constructed in
accordance with plans approved by the (Superintendent). The manhole shall be
installed by the owner at his expense, and shall be maintained by him so as to be
safe and accessible at all times.
Sec. 9. All measurements, tests, and analyses of the characteristics of waters and
wastes to which reference is made in this ordinance shall be determined in accordance
with the latest edition of "Standard Methods for the Examination of Water and
Wastewater, " published by the American Public Health Association, and shall be
determined at the control manhole provided, or upon suitable samples taken at said
control manhole. In the event that no special manhole has been required, the control
manhole shall be considered to be the nearest downstream manhole in the public
sewer to the point at which the building sewer is connected. Sampling shall be
carried out by cu-stomarily accepted methods to reflect the effect of constituents
upon the sewage works and to determine the existence of hazards to life, limb, and
property. (The particular analyses involved will determine whether a twenty-four
(24) hour composite of all outfalls of a premise is appropriate or whether a grab
sample or samples should be taken. Normally, but not always BOD and suspended
solids analyses are obtained from 24-hr. composites of all outfalls whereas pH's
are determined from periodic grab samples. )
Sec. 10. No statement contained in this article shall be construed as preventing any
special agreement or arrangement between the (city) and any industrial concern
whereby an industrial waste of unusual strength or character may be accepted by
the (city) for treatment, subject to payment therefore, by the mdustrial concern.
43-8
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The Model Sewer Ordinance
ARTICLE VI
Protection from Damage
1. No unauthorized person shall maliciously, willfully, or negligently break,
damage, destroy, uncover, deface, or tamper with any structure, appurtenance,
or equipment which is a part of the sewage works. Any person violating this
provision shall be subject to immediate arrest under charge of disorderly conduct.
ARTICLE VII
Powers and Authority of Inspectors
1. The (Superintendent) and other duly authorized employees of the (city) bearing
proper credentials and identification shall be permitted to enter all properties for
the purposes of inspection, observation, measurement, sampling, and testing in
accordance with the provisions of this ordinance. The (Superintendent) or his
representatives shall have no authority to inquire into any processes including
metallurgical, chemical, oil, refining, ceramic, paper, or other industries beyond
that point having a direct bearing on the kind and source of discharge to the sewers
or waterways or facilities for waste treatment.
2. While performing the necessary work on private properties referred to in
Article VII, Section 1 above, the (Superintendent) or duly authorized employees of
the (city) shall observe all safety rules applicable to the premises established by
the company and the company shall be held harmless for injury or death to the
(city) employees and the (city) shall indemnify the company against loss or damage
to its property by (city) employees and against liability claims and demands for
personal injury or property damage asserted against the company and growing out
of the gauging and sampling operation, except as such may be caused by negligence
or failure of the company to maintain safe conditions as required in Article V,
Section 8.
3. The (Superintendent) and other duly authorized employees of the (city) bearing
proper credentials and identification shall be permitted to enter all private properties
through which the (city) holds a duly negotiated easement for the purposes of, but not
limited to, inspection, observation, measurement, sampling, repair, and maintenance
of any portion of the sewage works lying within said easement. All entry and sub-
sequent work, if any, on said easement, shall be done in full accordance with the
terms of the duly negotiated easement pertaining to the private property involved.
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The Model Sewer Ordinance
ARTICLE VIII
Penalties
Sec. 1. Any person found to be violating any provision of this ordinance except
Article VI shall be served by the (city) with written notice stating the nature of the
violation and providing a reasonable time limit for the satisfactory correction
thereof. The offender shall, within the period of time stated in such notice,
permanently cease all violations.
Sec. 2. Any person who shall continue any violation beyond the time limit provided
for in Article VIII, Section 1, shall be guilty of a misdemeanor, and on conviction
thereof shall be fined in the amount not exceeding ( ) dollars for each violation.
Each day in which any such violation shall continue shall be deemed a separate
offense.
Sec. 3. Any person violating any of the provisions of this ordinance shall become
liable to the (city) for any expense, loss, or damage occasioned the (city) by
reason of such violation.
ARTICLE IX
Validity
Sec. 1. All ordinances or parts of ordinances in conflict herewith are hereby repealed.
Sec. 2. The invalidity of any section, clause, sentence, or provision of this ordinance
shall not affect the validity of any other part of this ordinance which can be given
effect without such invalid part or parts.
ARTICLE X
Ordinance m Force
Sec. 1. This ordinance shall be in full force and effect from and after its passage,
approval, recording, and publication as provided by law.
Sec. 2. Passed and adopted by the (Council) of the (city) of
State of on the day of (Month), (Year), by the
following vote-
Ayes • namely
Nays • namely
Approved this day of
(Signed) , (Mayor)
Attest
(Signed) . (Clerk)
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TRAINING FOR WASTEWATER TREATMENT PLANT OPERATORS
I INTRODUCTION
A The 1968 inventory of municipal waste
facilities (1) estimated that 70 million
people of 197 million population were
connected to sewage systems. Some type
of treatment was provided for 93% of the
connected population of which 65. 7% was
of the secondary type. During the six
years since the 1962 inventory, secondary
plant facilities had increased by 51% and
the population served by 40%. The 1968
report lists 12, 565 treatment plants for
12,911 communities. Facilities are being
provided at an increasing rate. These
plants stress secondary and/or advanced
treatment operations as necessary to
upgrade effluent quality. The operations
may be expected to increase in complexity
as more people are connected and as
treatment requirements increase.
B The report on Manpower and Training
needs (2) states "Still it is always the
skill of the people which transforms
inanimate buildings and machines into
productive devices."
1 Operating personnel for existing treat-
ment facilities perform remarkably well
in many cases. However, most existing
facilities are not functioning as well as
they could because of public indifference
after the plant is built and because
operating personnel commonly lack
training adequate for their responsibilities.
2 The community is committed to debt
service and default penalties. Operating
funds are not so protected. Consequently,
economy starts at the operating level.
The facility cannot serve its intended
function with a budget too low to attract
and hold competent trained personnel
with adequate funds for materials,
maintenance and repair.
C Operators are difficult to classify. The
operator in charge is responsible for all
phases of the facility. The shift operator
in a large plant may be responsible for a
limited assignment such as grit and trash
facilities. The small plant operator has
a difficult assignment because he may
have little backup support, must perform
all functions and frequently has had little
training for it. Overall functions in
operation include:
1 Inspection, housekeeping, meter reading,
adjustments, lubrication, repair,
reports of events and calculations
involving performance and costs.
2 Control of physical operations such as
screening, grinding, pumping,
clarification, aeration, filtration,
drying, etc.
3 Control of biological conditions
favoring desired performance for
aerobic, anaerobic or facultative
working organisms under varying
loading and conditions.
4 Control of chemical processes such as
neutralization coagulation oxidation
disinfection.
5 Perform sampling and testing operations
indicating work done or remaining to
be done.
6 Serve as an information source for
public officials, lay groups, suppliers,
consultants on specific facility problems.
D Technology is available today to clean our
environment if we accept performance as
the main criteria rather than cheapness.
Institutions are available for planning,
construction, and operation. Facilities
are in short supply. Trained qualified
SE. TT. 11.7.71
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Training for Wastewater Treatment Plant Operators
people are in shorter supply at all levels
of environmental technology.
E Environmental technology involves many
functional groups such as planning survey,
management, consultation, design, supply,
construction, maintenance and operation.
1 Training in the last group has tended to
be of the unplanned hit or miss category.
On-the-job training depends on the
co-workers attitude and has tended to
be spotty and slow without planned
training with rotated assignments.
2 Training must be suited for student
capability and background. The
specialist may be trained by abstracts
and theory, the intermediate level
operator by cause and effect examples,
entry level personnel may not even
know the terms for questioning.
3 Operator training stress is increasing
toward defining a job or task, designing
instruction for the task and student
background, and training personnel to
fit the description. To work effectively,
the definer, the instructor, and the
student must communicate in common
language.
4 Participant diversity in a given course
should not be so large that the entry
level student doesn't know the instructor's
language, the intermediate level student
can digest half of it and the advanced
student is bored from the start. Some
diversity is beneficial so that students
participate as instructors on familiar
topics.
F Each individual seeking to improve himself
must make do-it-yourself training a way
of life. Alertness during day to day con-
tacts is the most valuable learning asset.
Daily contacts include-
1 Trial and error or cause and effect
relationships. This is commonly called
experience.
2 Talk with available supervisors -
interest in their problems is likely to
reveal an amazing return interest.
3 Communicate with co-workers, on site
and nearby. It's likely that each has a
different response to a given situation,
each has a "bit" to contribute.
4 Talk with local officials, manufacturers
or supplier representatives, laymen,
teachers - anyone who may be, or can
be interested in wastewater treatment
operation.
5 Each facility have some training plan -
buddy system, counselor, rotating
assignment, question and answer,
topic development, reading program,
on or off-site courses, practice
sessions, or combinations thereof
Encourage this by active participation
in them during group sessions or
individual contact.
6 Become active in local, state and
national association affairs in the
field. Attend meetings where possible.
Discuss personal impressions with
others. Develop contacts with other
operators, regulatory officials,
instructors, industrial, consulting,
and lay groups.
7 Develop ability to read with a purpose,
use this ability regularly. Expand the
plant and home library with periodicals,
bulletins, texts, references, pertinent
news items or releases. Include at
least one good handbook and a
dictionary. Set up a system of storage
so that a given item can be found when
you need it. Use the public, school,
or trade library. Valuable source
materials are available on a no charge
basis from government agencies, schools,
associations, and suppliers.
G It is necessary to remain unsatisfied with
any given level of ability. It is not possible
to maintain a static capability level. Any
individual must improve or lose what is
not used. Use the seven senses diligently -
i.e. seeing, hearing, feeling, smelling,
taste, common, and hoi se. Partial
compensation is possible if you cannot use
one or more of these, there is no com-
pensation if you do not use available senses.
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Training for Wastewater Treatment Plant Operators
Enthusiasm is catching It may not be
possible to achieve all that enthusiasm
attempted but no group action persists
without enthusiasm.
H Training to upgrade entry and inter-
mediate level operating personnel to
increase the number of qualified wastewater
treatment plant operators is the major
interest of this outline. Graduate and
post graduate degree training, military
inservice training with operating or
environmental stress are very important
to total environmental upgrading but may
not be available for civilian personnel of
the interest level intended. Time and
space does not permit a complete listing.
Selected examples are used to indicate
current stress m training development.
II ACADEMIC TRAINING
A It is estimated that our youngsters have
had about 10, 000 hrs. of TV time prior
to primary school training. Activities in
class, projects, educational TV, films,
community, and lay groups increase
awareness of environmental problems.
Environmental consciousness may be
spotty but it's popular to be an ecology
"expert". Some of it is likely to register.
B Secondary schools are the terminal
academic level for a large segment of the
population. Changes have been and are
being made to adapt curricula to socio-
economic realities likely to be encountered.
Environmental training is part of this.
1 More and more high schools are
expanding present vocational training
or are developing new programs at the
junior and senior levels.
2 The Curriculum Activities Guide for
Water Pollution Control and Environ-
mental Studies prepared by The Tilton
School, Tilton, NH (FWQA Grant
1TT1-WP-41-01) is another example
of environmental activities at the
secondary school level.
3 Many other forms of environmental
emphasis are fostered by visual aids
interests, commercial developers,
text book publishers, trade associations,
conservation or public interest lay
groups and individual instructors or
their associations.
C Post High School Technician Training
Vocational training for the high school
graduate has increased very rapidly in
the past few years. Less than 20
vocational schools offered environmental
training courses prior to 1968. A partial
listing from the National Sanitation
Foundation, Ann Arbor, MI, dated
November 1970 included 70 post-secondary
schools with environmental training in
23 states. Most of these are based upon
two year curricula. It is not known how
many of these are engaged in courses
specific for water and wastewater.
1 These courses are intended to train
technicians for job entry level
capabilities in environmental operations.
2 The community college or vocational
school is favorable for development
of special courses for local development.
a The instructor staff may be a blend
of professional teachers and working
specialists.
b The course may include on-the-job
training at appropriate points in the
schedule.
c Liaison of academic and working
knowledge provides a center of
information on specific questions
from local operators.
d Special topic seminars or short
courses may be developed for evening
or daytime sessions.
D University courses traditionally have
stressed theory and abstracts for planning,
management, consulting construction,
design regulation and related specialties.
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Training for Wastewater Treatment Plant Operators
Relatively small percentages of degree
students have entered operations except
in large or complex treatment facilities.
1 Undergraduate curricula have changed
or are changing toward an interdisciplinary
approach and process dynamics.
2 Post graduate curricula are tending to
be adapted more closely to student
program interest than to rigid course
schemes.
3 Courses tend to be more closely related
to total environmental interest than to
an isolated segment of it.
4 The Association of Professors of
Sanitary Engineering have instituted
several activities to encourage better
student coordination with procedures
outside of the university.
E University non-resident training is
unusually varied, such as:
1 Universities have been a source of
materials, site of, and have provided
instructors for many short term
seminars, courses, or other training
in conjunction with federal, state,
industrial or professional groups.
2 The Programmed Instruction Series
for Water Pollution Control developed
at the University of Michigan Center
for Research and Learning by Drs. K.H.
Mancy and L. A. Pursglove is a relatively
new approach to self-study for operators.
3 The Correspondence Course developed
at Clemson University, Clemson, SC
for South Carolina operator training,
2nd Ed., Dr. John H. Austin, Editor,
is another form of operator instruction.
4 The Seminar on Educational Systems for
Operators of Water Pollutional Control
Facilities sponsored by the U.S. Dept.
of Interior, FWPCA and Clemson
University at Atlanta, GA, November
1969 was important for orientation of
past, present and future operator
training considerations.
5 Sacramento State University,
Sacramento, CA, Dr. Kenneth D.
Kern, Director, has prepared a
correspondence course for operators
that has input from both educators
and operators. This project currently
is in the finishing stages for printing.
6 Books, reports on special investigations,
manuals, etc. have been prepared on
special topics under sponsorship of
contracting agencies.
Ill WATER POLLUTION CONTROL
FEDERATION ACTIVITIES-
A Advancement in the state of the art in all
phases of water pollution control is the
major charter commitment of the WPCF.
1 Publication of articles relating to
planning, design, administration,
research, and facilities operation,
municipal and industrial, have been
continued in the Federation Journal
since its inception in 1928.
2 The Manual of Practice Series have
been prepared by member committees
to reflect established practice and
recommendations for special topics.
MOP- 1 considers safety practice,
MOP-20 considers sludge dewatering.
These are updated at intervals depending
upon changes m stress or state of the
art and upon committee activities.
3 The WPCF acts in a liaison capacity
among federal,interstate, state,
university, industrial, and local
agencies. It acts as an information
source for agencies or individuals,
professional associations and lay
groups. As a professional association,
it provides recommendations pertaining
to proposed actions with an environmental
impact.
a Model legislation on matters related
to water pollution control organization,
enforcement, certification and related
regulations have been devised as
guidelines for consideration by
governing bodies and interested groups.
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Training for Wastewater Treatment Plant Operators
b Suggested plans for organizing
functional groups for implementation
of WPC are available for use by
public or corporate agencies.
c The WPCF serves with inter-
professional associations such as
the APHA, ASCE, AWWA and others
on matters related to common
interests such as design, standard
methods, terminology.
4 The organization sponsors national,
state, regional and local meetings,
seminars or discussions of common
interest to improve individual contacts
and capabilities for working in a team
effort.
B Interest in operator status training and
performance upgrading is a continuing
objective. Recent trends have resulted
in increased stress toward upgrading
apprentice personnel and continued
development of the operator who has not
had the benefit of special training.
1 Mandatory certification of operator
personnel has been a long term goal
to increase status of personnel,
continuity and performance of existing
treatment operations. Uniform
certification has not been realized but
they have become more consistent and
comprehensive. As of January 1, 1971,
27 states had mandatory certification,
20 had voluntary programs and 3 had no
formal program. Mandatory certification
is pending in several states.
2 Training materials and programs have
been formulated for two courses by
committees of the WPCF to guide
state, local, and other groups to provide
improved training to upgrade personnel
for operational capability. Strong
emphasis on safety training earned a
national safety award 1970.
3 The Personnel Advancement Committee
assembles data on existing certification,
personnel training practice and provides
guidance pertinent to new or developing
programs.
C A Workshop on Operator Training held at
the Dallas meeting of the WPCF,
October 1969, led to a new program
emphasizing operator training needs and
problems. Project "Manforce" has
resulted from this effort. Manforce has
assumed certain obligations of other
activities of the WPCF, and parallels
certain federal and state programs. It
has a new organizational structure and
limited staffing to date but certain factors
are becoming evident to foster improved
operator interest.
1 The "Deeds and Data" section of
Highlights" is a new publication now
appearing monthly that is written
specifically for operators. It includes
a sounding board for operators,
information on operating safety, training
questions, discussions, definitions and
tips.
2 A new committee for operator certification
has been formed, Terry M. Regan,
Chairman, Kentucky Certification
Board, to enhance certification
uniformity.
3 The Black and Veatch report on
operator and specialist job descriptions
and staffing for wastewater treatment
facilities has been reviewed by
Personnel Advancement and Manforce
Committees. Intent is to assist job
classification and recommended
staffing requirements for operations.
4 A new staff member has been employed
as Director of Education and Training.
5 Top priority has been assigned to
a Uniform certification
b Manpower needs and salary
c Recruitment and retention of
capable operating personnel
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Training for Wastewater Treatment Plant Operators
IV- STATE AND LOCAL OPERATOR TRAINING
Primary responsibilities for water quality,
planning, development and implementation
are state functions. Local agencies work
within the state framework and regulations
on front line functions of treatment technology.
A Certification authority and programs vary
from state to state. An effective certification
program requires a good entry level
training program. This must be backed
by effective recruitment, meaningful
training and salaries adequate to hold
trained personnel.
1 The common 1 to 5 day intensive
training course at one year intervals
at central locations continues to be
useful for upgrading intermediate and
advanced operator personnel. These
groups have better contacts, usually
can participate in monthly association
or other meetings and have a better
chance to continue their education by
means not available to entry level
personnel.
2 Entry level personnel usually require
many more hours of training in
terminology, equipment and task
identification, practice, and basic
arithmetical manipulations. This
generally means that training must be
brought to the recruit to minimize
travel restrictions.
3 The states have power to certify and to
enforce. Sometimes home rule or other
limitations make it difficult to implement
adequate staffing and budget allowances
to attract and hold competent local
personnel on a state-wide basis. Public
relations and certification help.
B Entry level training has been expanded and
is being offered at more sites. More
expansion is needed. Instructors capable
of productive training in treatment operation
are difficult to locate - they generally must
be developed and trained to present that
which the apprentice needs in a manner
understood by him.
1 The plant manager is becoming more
conscious of personnel training
responsibility. He may delegate
training responsibility to others, but
he is responsible for results.
2 Community colleges are becoming
more numerous and more active as
environmental training centers.
3 The public expects more, hopefully,
they can be educated to the fact that
environmental quality is not a free-
ride. Service charges and other
activities are moving m the direction
of more realistic funding.
4 Local high school vocational training
is improving. Use of the facilities for
mixed academic and on-the-job training
is expanding.
5 An increasing number of States have
full time training directors, committees,
and instructors for local training.
a Special training committees have
been formed to contract for, receive
money, and handle disbursements
for training materials such as the
Texas, California, New York,
South Carolina and the Ohio training
materials.
b Special state personnel have been
designated for on site visits or
group meetings for local training
purposes.
c Support may be arranged for
supplementary payment for local
operator time devoted to training
efforts.
d An increasing number of courses
are becoming available where the
participant receives combined class
and on the job training (OJT).
V FEDERAL TRAINING ACTIVITIES
A The Federal Role in wastewater operator
personnel training commonly is an
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Training for Wastewater Treatment Plant Operators
interagency function among federal, state
or local governments, universities,
corporations, associations or other
contracting bodies. Financial support
may be partial or complete through con-
tracts grants or projects.
1 Objectives may include programs for
staffing, curricula, manuals, visuals,
lesson plans etc. to be used by others
in class, home study, correspondence
or other personnel training.
2 Financial support may be partial or
complete for programs including
instruction, materials, and administration
by state or local agencies.
3 Joint federal, state or local input as
agreed upon to fit the situation is
common.
4 Direct federal training including funding,
administration, supervision, instruction
materials with or without student support
may be provided.
B The office of Water Programs, EPA
through the Division of Manpower and
Training, State and Local Manpower
Development Branch anticipates training
approximately 2600 individuals in the next
fiscal year. These programs are funded
through the Department of Labor and the
Department of Health,Education and
Welfare as follows-
1 Institutional Training Program
Conducted at Community Colleges or
Vocational Training Schools in nine
states are presently planned (NY, MD,
GA, OH, CA, MO, LA, TX, and ID).
Two 22 week courses for 20 participants
each include 440 hours of class
instruction and an equal amount of time
for practical experience in plant treat-
ment. Approximately 360 enrollees will
be trained for $734, 000 with trainee
allowance of $400, 000. Instructors,
supplies, equipment, administration,
supervision and placement costs are
included.
2 The Transition Training Program will
be conducted at military installations
with or near treatment plants and
academic institutions (five locations
now). Trainees at army bases will
receive 240 hours of training, 640 hours
at a marine base. Enrollees will be
trained in groups of 12 including
servicemen in their last 6 months of
duty. Program cost is $245, 000 for
instructors, supplies, equipment,
supervision and placement of successful
trainees. Students may qualify for
Veterans Administration approved on the
(OJT) additional training.
3 The coupled OJT National Projects
will be conducted in 27 states with a
total of 50 project sites. Each
subcontractor is a unit of the state
government, a municipality, a waste
treatment district or community
college. 70% of enrollees will be in
skill improvement training, 30% at
entry level. A total of 1000 individuals
will be trained at a cost of $1,260, 000.
Approximately $300, 000 will be used
for instructors, supplies, equipment,
administration and supervision.
4 The Public Careers Program is
presently underway in VA, SC, TX
(2 locations) WI and the Virgin Islands.
Sponsors are charged with finding
existing vacant positions and providing
training at entry level as well as
upgrading. Approximately 400 new
and 500 upgraded individuals will be
trained at a cost of $1, 500, 000 of which
$1, 200, 000 will be for instruction,
equipment, supplies and supportive
services.
C The previous section represents a rapidly
expanding ongoing program of federal,
state and local activities.
45-7
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Training for Wastewater Treatment Plant Operators
1 Completed MDTA projects supported
by the Depts. of Labor, HEW, Interior,
and cooperating agencies in Indiana,
Ohio, Kentucky and West Virginia
during FY 70 include:
IN 6 projects
OH 1 project
KY 2 projects
WV 1 project
4 cities 131 individuals trained
1 city 19 individuals trained
2 cities 60 individuals trained
1 city 32 individuals trained
2 These projects were similar to that
described in V, B3. They were in
addition to established state and local
operator training for entry level
personnel and upgrading existing
operator personnel. Similar training
has been given in many states besides
the examples cited. New mandatory
certification programs and higher
treatment requirements have dictated
many new or greatly expanded personnel
training activities. Other new training
facilities are being developed.
D Federal support of training through the
Training Grants Branch of the Division
of Manpower and Training usually is in
the form of Grants, Contracts, or Project
funding to some delegated agency such as
universities, professional associations,
consultants.
State or Local Agencies
1 Among others these include previously
described projects such as III B C D E,
IV A. 2, C. 3.
2 Training Grants for academic
institutions may include student and
project support.
3 Community colleges and other training
institutions are encouraged by contract.
E The Direct Training Branch of the Division
of Manpower and Training engages in short
term intensive training courses for planning,
supervisory, technical and instructor
personnel.
These are located m Ada, OK, Athens, GA,
Cincinnati, OH (National Training Center),
Corvallis, OR, Edison, NJ and Fairbanks,
AK.
Training support for operator personnel
includes-
1 Consultation, source information,
visiting lecturers, topic background
materials or lesson plans, and
coordinating assistance for local
training.
2 Courses specifically directed toward
operator instructor personnel on
technical background and instruction
methodology are offered.
3 A catalog of tape/slide audio visual
presentations has been developed and
is expanding for circulation to state
or local training groups as a nucleus
for special topic presentation-
discussion sessions.
4 Study carrels for self-instruction on
basic information are being developed.
5 Administrative and technical guidance
for correspondence training is nearing
implementation.
F Technology Transfer Program of the EPA
1 This effort is not specifically operator
training but plant operation is not
possible without versatile and operable
plants in line with need. This program
is aimed for those who provide the
facilities. The Technology Transfer
Program of the EPA recognizes that
advanced technology will not be used
unless three groups apply it. Specific
parts of the program are directed toward:
1) the design engineer; 2) the administrator;
3) the public information group.
Technology Transfer was announced as a
top priority item of the EPA by
Commissioner Dominick at the 43rd
Annual Conference WPCF at Boston,
MA in October 1970.
45-8
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Training for Wastewater Treatment Plant Operators
a The Headquarters Advisory Board
consists of three Regional Directors,
two members of the Office of Water
Program and one each from the
Advanced Waste Treatment Laboratory
and Facilities Construction.
b A Headquarters Working Committee
includes two representatives from
Research and Development, one
each from Facilities Construction,
Manpower Training and Public Relations.
c Each Region has a Working Committee.
3 The program evolved from Seminars
and Workshop Sessions of the AWTR
group that listed 3464 attendees from
administrative, consulting, design,
technical personnel, professional and
lay personnel in 11 major cities from
July 1, 1968 to February 1971.
4 The first seminar/workshop under the
new program other than for organization
and development purposes was held at
Chapel Hill, NC February 8-9, 1971.
One was held m Cleveland, OH in
April 1971, one in Boston m May and
another at Charlottesville, VA in
June 1971.
5 The problem is that plants tend to be
designed as they have been designed.
The Technology Transfer Program is
intended to transmit sufficient
technology to design and construction
engineers so that the most efficient
treatment facilities can be designed
and constructed at favorable cost/
benefit ratios. Plans as of March 1971
include:
a Program for contributing engineers
(By January 1974)
1) 36 seminar/workshops for con-
tributing engineers distributed
among all regions.
2) National meetings and conference
information, exhibits, talks
(4 national meetings).
3) Available information at local
meetings (7 5 local meetings)
4) Exploit demonstrations of new
technology, visits, visuals and
presentations.
5) Issue 8 design manuals, 12
newsletters and several technical
bulletins.
6) Provide current operation and
maintenance procedures to
engineers in liaison with the
Manpower and Training Program.
b Program for administrators
(By January 1974)
1) Conduct 32 administrative work-
shops (all regions).
2) Publish 9 State of the Technology
Articles in non-technology journals.
3) Conduct an information program
for administrators and public
officials - semi-technical
publications.
c Program for public information
groups (January 1974)
1) Provide current information to
local action groups leaflets -
newsletters - lectures - tours.
2) Initiate national and local public
information campaign using all
media - TV documentaries,
public displays.
3) Initiate national recognition
program for successful transfer
and use of new technology -
awards to waste treatment plants
G Each Regional Office of the EPA has a
Manpower and Training Coordinator for
their area.
45-9
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Training for Wastewater Treatment Plant Operators
VI SUMMARY
A Operator personnel training is a function
of many interrelated organizations such
as government agencies, professional,
industrial, manufacturing, supply,
educational institutions and all levels of
personnel within the organizations. To
work, personnel training is a personal
responsibility of each individual in the
system.
B Personnel training necessarily must be
adapted for communication among various
levels of responsibility, job descriptions
and pre-existing capabilities of the trainee.
1 Entry level personnel require a knowledge
of what is expected from their assigned
tasks, language training, identification
of tools and processes and how to do it
practice among assigned tasks.
2 Intermediate level personnel require
development of cause and effect
relationships, expansion of task
oriented capabilities and continuing
development in how each bit fits into
the whole.
3 Advanced level personnel require
emphasis on integration of effort to
improve performance with available
or obtainable people, equipment and
tools.
C Motivation is the basis for growth of
personnel capabilities. Recognition of
gain as a result of effort expended may
take the form of
1 Monetary reward
2 Public recognition
3 Increased and varied interests
4 Greater responsibilities
5 Improved working conditions
6 Status improvement from a standpoint
of job security, choice of assignment,
location, etc.
7 A feeling of doing something important.
D Training is a primary responsibility of
line operating personnel and their
immediate supervision. Planned training
is essential for continued development of
personnel capabilities. Class work
hastens development but applications
make it meaningful.
ACKNOW LEDGEMENTS:
Many individuals, federal, state and local
contributed information included in this
outline. Special thanks are due to Daniel D.
Daniels, Chief, State Training Activities,
EPA, Joseph D. Lipps, Training Coordinator
of the previous Ohio Basin District now part
of EPA, Region V, Robert A. Canham Exec.
Sec. WPCF, Sam L. Warrington, Chairman,
Personnel Advancement Committee, WPCF
and F.M. Middleton, Director, Advanced
Waste Treatment Research Laboratory, EPA.
Additional Reading-
1 Municipal Waste Facilities in the United
States. U.S. Dept. of the Interior,
FWQA, 1968.
2 Senate Document No. 49, 90th Congress
Manpower and Training Needs in Water
Pollution Control, 1967.
3 Educational Systems for Operators of
Water Pollution Control Facilities,
Clemson University and Dept. of the
Interior. November 1969, Atlanta, GA.
4 Robert F. Mager and Kenneth M. Beach, Jr.,
Developing Vocational Objectives.
Fearon Publishers, Palo Alto, CA.
This outline was prepared by F. J. Ludzack,
Chemist, National Training Center, OWP,
EPA, Cincinnati, OH 45226
45- 10
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EVALUATION OF WASTEWATER TREATMENT PROGRAMS
Municipality Date Rated by Score
(A) Degree of treatment and Effluent Quality based on Suspended Solids
and BOD removal during lowest flow month of previous year. (Max 25)
I. For plants employing only Primary Treatment (with or without
chemical precipitation)
1. i point for each percentage of removal above 40 (BOD)-(Max. 5)
2. 4 point for each percentage of removal above 55 (Suspended
Solids) (Max. 5)
3. £ point for each mg/1 of BOD in effluent less than 120 (Max. 5)
4. i point for each mg/1 of Suspended Solids in effluent
less than 90 (Max. 5)
(Max. Total 20 )
II. For Secondary Treatment Plants
1. ipoint for each percentage of removal above 75 (BOD) (Max. 5)
2. i point for each percentage of removal above 75
(Suspended Solids) (Max. 5)
3. 4 point for each mg/1 of BOD in effluent less than 30 (Max. 5)
4. i point for each mg/1 of Suspended Solids in effluent
less than 30
5 Minimum removal of BOD for any month in previous
year add 2 point for each percentage of removal in
excess of 80 (Max. 5)
(Max. Total 25 )
(B) Amount of Bypassing (untreated sewage) taking place either at the plant
or on the system. (Max. 10)
1. Occurs on separate occasions on at least nine months
of the year (0)
2. Occurs on separate occasions on at least six months
of the year (2)
3. Occurs on separate occasions on at least three months
of the year (4)
Points
SE. MAN. 10. 9. 69
46-1
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Evaluation of Wastewater Treatment Programs
4. Does not occur at any time
5. Does not occur and the flow into the plant does
not exceed twice the design capacity of the entire
plant
(MAXIMUM MONTHLY FLOW)
(C) Competency of operators based on certification (determined
by the lowest coverage of any one-month period during
previous years) (Max. 10)
1. Neither certified operator nor technical supervisor
available
2. Technical supervisor available - no other certified
personnel available
3. Technical supervision with one or more full time
man certified
4. Certified operator in charge meeting the
certification requirements of the plant
a. If plant serving less than 5, 000 PE, and under
responsible charge of properly certified operator
5. Properly certified operator in charge plus certified
operators on duty with total certification equal to
or exceeding required certification
(D) Capacity of plant based on minimum approved design of any
major plant component. Flow based on annual monthly
averages of preceeding year. (Max. 10)
1. Annual monthly average flow exceeds plant capacity
2. Annual monthly average flow 90 - 100% plant capacity
but detail plans not approved
3. Annual monthly average flow 90 - 100% plant capacity
and detail plans approved
4. Annual monthly average flow 80 - 90% plant capacity
5. Annual monthly average flow 80 - 90% plant capacity
and general plans approved for plant expansion and
detail plans being prepared
6. Annual monthly average flow less than 80% of plant
capacity
Add to Above
la. Maximum monthly average flow exceeds 1.5 X
design capacity
Points
(6)
(10)
(0)
(2)
(4)
(8)
(10)
(10)
(0)
(1)
(2)
(4)
(5)
(5)
(0)
46-2
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Evaluation of Wastewater Treatment Programs
Points
2a. Maximum monthly average flow less than 1. 5
design capacity (3)
3a. Maximum monthly average flow less than design
capacity (5)
(E) Condition of the receiving stream based on visual evidence of
pollution at any critical time during the year and also based on
stream sampling done by the operator, (minimum monthly
average for previous year) (Max. 20)
1. Visible evidence of septic conditions, formation of
sludge banks, emanation of odors, or unsightly amount
of substances attributable to sewage discharges (0)
2. Visible evidence of gray filamentaceous bottom growths
on the stream bed below the outfall or evidence in plant
records of a D.O. of less than 5 but greater than 2 mg/1
in the receiving stream (5)
3. Visible evidence of turbid conditions in ponded areas of
the receiving stream or slight evidence of sewage
residual along the stream banks and plant reports
indicate D.O. greater than 5 mg/l
4. No visible evidence of plant discharge or stream
pollution at the time of the review and plant reports
indicate D.O. greater than 5 mg/1 in the receiving
stream
5. No visible evidence of plant discharge or stream
pollution at the time of the review and plant reports
indicate D.O. greater than 5 mg/1 in the receiving
stream. Also, adequate disinfection of the effluent.
6. For plants discharging to large rivers or lakes where
evaluation of the effect of a single plant on the receiving
waters is difficult, points given shall be based on the
degree to which the plant meets effluent standards
established for the stream in question.
Receiving Water
Established Effluent Standards: Months Eeqd. Months Met
% BOD Removal
Disinfection
(10)
(15)
(20)
Months met X 20
Months reqd.
Total
(Max. 20)
46-3
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Evaluation of Wastewater Treatment Programs
Points
(F) Control of all sources of pollution within the municipality
(Max. 15 Minimum 0)
1. Evidence of significant quantities of improperly
treated sewage or industrial wastes being discharged
to streams or storm sewers within the municipality.
Exclude wastes from industries and other separate
sources under permit.
2. No evidence of improperly treated waste discharges
but individual systems utilized for over 10% of the
municipal population
3. No evidence of improperly treated waste discharges
but individual systems utilized by 3 to 10% of the
municipal population
4. No evidence of improperly treated waste discharges
and less than 3% of the municipal population served by
individual systems
5. All sources of wastes connected to the sanitary sewer
From the total noted above deduct the following
2 X the % of homes equipped with questionable treatment
devices (septic tanks only or less) discharging to storm
sewers or waters of the State. If the system has not
been checked or upgraded by the local health department
in ten years, it is considered "questionable".
Points Deducted
2 X the % of industries (by number) served with indi-
vidual systems not under W.P.C.B. permit or a valid
local surveillance program
Points Deducted
Total for F Category - Max. 15 - Minimum 0
(G) Appearance of the plant and the plant grounds. (Max. 10)
1. Plant grounds and plant operation not esthetically
attractive (0)
2. Plant grounds and plant operation are esthetically
attractive (10)
This outline was prepared by F J Carlton, Assistant District Engineer, Ohio State Board
of Health, Dayton, OH 45402.
(0)
(5)
(10)
(15)
(15)
46-4
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GLOSSARY - WASTEWATER TREATMENT TECHNOLOGY
This is a selected list containing the key
ideas of terms likely to be encountered
in treatment technology.
ABSORPTION - The taking up of one sub-
stance into the body of another .
ACRE FOOT - A volume term referring
to that amount of liquid 1 acre in area
and a depth of 1 foot. 43, 560 cu. ft.
ACID - Most commonly refers to a large
class of chemicals having a sour taste
in water, ability to dissolve certain
metals, bases or alkalies to form salts
and to turn certain acid-base indicators
to their acid form. Characterized by
the hydrated H4" ion.
-^ACTIVATED SLUDGE - A process used for
purification and stabilization of waste-
waters by mixing of the solids concen-
trate from previous contact with raw
or settled wastewaters under turbulent
oxygenating conditions for sufficient
time to permit transfer of nutrients
to the solids phase, partial biodegra-
dation and clarification of the water
before discharge.
ADSORPTION - The taking up of one sub-
stance upon the surface of or interface
zone of another substance.
-^ADVANCED WASTE TREATMENT -
Renovation of used water by biological,
chemical or physical methods that are
applied to upgrade water quality for
specific reuse requirements. May
include more efficient cleanup of a
general nature or the removal of com-
ponents that are inefficiently removed
by conventional treatment processes.
AERATION - The operation of adding oxygen
to, removing volatile constituents from,
or mixing a liquid by intimate contact
with air.
AERATION PERIOD - A theoretical time
usually expressed in hours equal to
the volume of the tank divided by the
volumetric rate of flow.
•^^"AEROBIC - A condition characterized by
an excess of dissolved oxygen in the
aquatic environment.
AT. 2. 8. 69
*¦
For more scientific definitions or unlisted
terms, consult the list of references at the
end of the glossary.
AEROBIC BACTERIA - Organisms that
require dissolved oxygen in the
aquatic environment to enable them
to metabolize or to grow.
AGGLOMERATION - An action by which
small particles gather into larger
particles that are more readily
separated from the liquid by sedi-
mentation or other means. May be
the result of biological, chemical
or physical factors.
AIR LIFT - A pump consisting of a vertical
pipe immersed in a liquid into which
air is mixed to reduce specific gravity
of the air-liquid mixture. The net
effect is to raise the liquid level in
the discharge pipe.
ALGAE - Primitive plants, one or many
celled, usually aquatic and capable
of growth on mineral materials via
energy from the sun and the green
coloring material, chlorophyll.
Generally considered as the primary
source of food for all other organisms.
ALKALINITY - A term used to represent
the sum of the effects opposite in
V? reaction to acids in water. Usually
Hi" due to carbonates, bicarbonates and
hydroxides; also including borates,
silicates and phosphates.
AMPEROMETRIC CHLORINE RESIDUAL -
A means of determining residual
available chlorine with phenyl arsene
oxide (PAO) titration using current
response as an indicator of equiva-
lence. For wastewater, the PAO
preferably is used in excess with
iodine backtitration.
^^"ANAEROBIC - A condition in which dis-
solved oxygen is not detectable in
the aquatic environment. Commonly
characterized by the formation of
reduced sulfur compounds from the
use of bound oxygen from sulfates
as an hydrogen acceptor.
47-1
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Glossary - Wastewater Treatment Technology
^ANAEROBIC BACTERIA - Organisms that
can metabolize and grow in the absence
of dissolved oxygen. Their oxygen
supply is obtained from the bound oxy-
gen such as in sulfates, carbonates,
or other oxygen-containing compounds.
ANION - A negatively charged ion in water
solution. May be a single element or
a combination of elements, such as
the CI" ion in a water solution of NaCl
(common table salt) or S04= ion in a
sulfuric acid solution.
ASSESSMENT - A legal financial obligation
of the property owner in an irrigation,
water, drainage or sanitary district,
created for the purpose of financing
the construction and operation of
facilities required to protect and en-
hance public benefit within the district.
ATTACHED GROWTH - Plant or animal
growth that tends to seek a solid sur-
face for a point of attachment from
which to grow, in contrast with free-
swimming or suspended organisms.
ATOM - An extremely small unit or particle
of an element consisting of a positively
charged nucleus and one or more
negatively charged electrons. Atoms
of different elements are different in
mass and the number of electrons.
Electrons may be located in the nucleus
or externally. The external electrons
determine chemical combining power.
ATOMIC WEIGHT - A relative mass of an
atom of an element compared to
carbon-12. Maybe expressed in
grams (g), pounds or other consistent
weight units when used for process
control.
^AVAILABLE RESIDUAL CHLORINE -
Generally refers to that part of the
chlorine that will react with ortho
tolidine or amperometric tests and
exhibits significant germicidal activity.
A WW A (AMERICAN WATER WORKS
ASSOCIATION) - An organization composed
of individuals engaged in research,
design, operation and control in the
advancement of knowledge related
to potable water supply
BACTERIA - Primitive organisms having
some of the features of plants and
animals. Generally included among
the fungi. Usually do not contain
chlorophyll, hence commonly require
preformed organic nutrients among
their foods. May exist as single cells,
groups, filaments, or colonies.
BACTERIACIDE - Any component that
will kill or destroy bacteria.
BACTERIOSTATIC - A condition during
which the normal metabolic functions
of bacteria are arrested until favor-
able conditions are restored.
BACTERIOLOGY - See Microbiology.
BAFF LE - A deflector or check such as
a vane, guide boards, plates, grids,
grating, or similar devices used
to control the flow distribution or
velocity of liquid in a channel or
basin.
BAR RACKS (SCREENS) - A coarse
screen usually consisting of bars
spaced with 1 to 5 inch openings
to trap roots, branches, rocks,
rags, and other large materials
that may be encountered in the flow
of a channel or conduit.
BASE - A foundation, plate, natural or
engineered support upon which a
structure, channel, machine, or
other device is mounted.
Chemical: A base includes a large
variety of chemicals opposite in re-
action to acids (alkali).
BED LOAD - Generally refers to the
oxygen demand requirements of
benthic deposits, sludge, muck,
attached growths, moving materials,
living or dead that are exerted upon
waters as a result of bottom or
boundary dynamics.
BENTHIC DEPOSIT (BENTHOS) - Refers
to the accumulated deposition of cell
mass living or dead that collects at
the bottom of a stream impoundment
where velocity or catchment permits.
47-2
-------
kJprrr? $,3P
PC- *
Glossary - Wastewater Treatment Technology
BIO-CHEMICAL, - Resulting from the
combined activities of biological
and chemical transformations.
Usually measured in terms of the
ensuing chemical changes.
-^BIODEGRADATION - The stabilization
of wastewater contaminants by bio-
logical conversion of pollutants into
separatable materials at a higher
oxidation state.
BIO FILTER - See Trickling Filter.
BIOLOGICAL PROCESSES - Activities of
living organisms to sustain life,
growth, and reproduction. Commonly
the processes by which organisms
degrade complex organic material
into simpler substances at a higher
oxidation state to obtain energy for
life processes and growth of new
cell mass.
BIOLOGY - The science and study of living
organisms, characteristics and be-
havior.
BOD - Biological or biochemical oxygen
demand. A test for estimation of
wastewater polluting effects in terms
of the oxygen requirements for bio-
chemical stabilization under specified
conditions and time.
BRIDGING - A condition in which particu-
lates or solids concentrates that would
normally seek the lowest level of a
restricted channel or basin, tend to
hang up on sidewalls. The bridged
material commonly may settle again
with vibration, agitation, a change
in flow direction, or increased flow
velocity.
BTU (BRITISH THERMAL UNIT) - That
amount of heat that will raise the
temperature of one pound of water
one degree Fahrenheit.
BUFFER ACTION - An action exhibited
by certain chemicals that limits the
change in pH upon addition of acid
or alkaline materials to the system.
In surface water, the primary buffer
action is related to carbon dioxide,
bicarbonate and carbonate equilibria.
BULKING - A condition, usually related
^ to activated sludge processing, in
which the sludge solids separation
from the liquid is inhibited.
Rapid growth, filamentous organisms,
and certain other factors that are but
vaguely understood, tend to produce
a low density thin sludge that settles
very slowly and has limited compact-
ability.
BURNER, WASTE GAS - A device for
burning the excess gas from sludge
digestion.
CALORIE - That amount of heat required
to raise one gram of water one
degree Centigrade, or Celsius.
CARBOHYDRATES - Naturally occurring
compounds consisting of carbon,
hydrogen and oxygen, that are con-
sidered as energy foods and precursors
of proteins and fats in the natural
food chain.
CATALYST - A substance that influences
the rate of chemical change but either
remains unchanged during the reaction
or is regenerated thereafter.
Generally applies to acceleration of
reaction rates.
CATCH BASIN - A chamber, well or other
enlargement of a channel, designed
to retain grit and detritus below the
point of liquid overflow.
CATION - A positively charged ion in
water solution. May be a single
element or a combination of elements,
such as Na+ in a water solution of
NaCl (common table salt).
CENTI - An expression used to indicate
1/100 of a given standard unit
centimeter (cm). 1/100 meter.
CENTIGRADE - A temperature measure-
ment scale in which the freezing point
of pure water at sea level is desig-
nated as 0°C and the temperature of
boiling water is designated as 100°C.
This is more properly termed the
Celsius scale.
CENTRIFUGAL PUMP - A pump consisting
of a rotating impeller within a casing
having an inlet near the center and
an outlet or discharge at the tip of
the impeller where centrifugal force
is greatest.
47-3
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Glossary - Wastewater Treatment Technology
*
*
*
CENTRIFUGE - A device for separation of
solids or liquids of different densities
by rotational energy; heavy materials
move outward, less dense materials
move toward a central take-off port.
CHANNEL - A natural or artificial waterway
which continuously or periodically con-
tains flowing water. A connecting link
between two bodies of water with a
definite bed and sidewalls to confine
the flow.
CHANNELING - A condition in which certain
portions of the flow within a channel or
basin tend to seek a more limited dis-
tribution than that resulting from the
confining bed or sidewalls, i. e., the
flow may channel along the top, bottom
or mid channel depth due to density,
temperature, or some form of obstruc-
tion to uniform cross sectional flow.
CHECK VALVE (FLAP GATE) - A device
to control flow in a pipe or channel
limiting it to one direction. Commonly
a gate hinged at the top that is limited
in mo/ement by a seat in a near
vertical position so that it can open
for flow in one direction but closed
by reverse flow.
CHEMISTRY - A science that deals with the
composition and characteristics of
substances and their behavior, 1. e. ,
the transformations that they undergo.
CHLORAMINES - Products of the combination
of chlorine and ammonia. Commonly
classified as combined available chlorine.
CHLORINE - A greenish yellow gaseous
element having strong disinfecting
and oxidizing properties in water
solution. It is commercially available
as compressed gas, liquid, or in
combined form as a powder. It is
highly toxic and irritating to skin, eyes,
and lungs in significant concentrations.
CHLORINATION - The application of chlorine
to water or wastewater for the purposes
of disinfection, oxidation, odor control,
or other effects. Pre-chlonnation -
before treatment, post-chlorination -
after treatment; in-process chlorination
- during treatmont.
CHLORINATION CHAMBER - A basin or
tank where chlorine is applied to the
liquid.
CHLORINE TEST - Commonly refers
to one of two methods separately
listed: see Ortho tolidine test;
see Amperometric test.
CHLORINE DEMAND - The difference
between applied chlorine and residual
available chlorine in aqueous media
under specified conditions and
contact time. Chlorine demand
varies with dosage, time, temperature,
nature and amount of the water im-
purities.
CHLORO ORGANIC COMPOUNDS -
A broad group of compounds containing
chlorine, carbon, hydrogen and some-
times other elements. Generally
originating from or associated with
living or dead organic materials. This
group shows a wide range of toxicities
but usually have relatively little oxi-
dizing energy compared to chlorine.
CHLOROPHYLL - The green coloring
material or pigments in plants that
promotes the photosynthetic reactions
forming organic materials from in-
organic nutrients and light energy
within the living cells.
CLARIFIER - A basin or chamber serving
as an enlargement of a channel to re-
duce flow velocity sufficiently to per-
mit separation of settleable or
floatable materials from the carrier
water (a sedimentation basin).
COAGULANT - A chemical, or chemicals,
which when added to water suspensions
will cause finely dispersed materials
to gather into larger masses of im-
proved filterability, settleability, or
drainability.
COAGULATION - The process of modifying
chemical, physical, or biological
conditions to cause flocculation or
agglomeration of particulates.
-^eCOD - A test for the estimation of the
contamination of a wastewater in
terms of oxygen requirements from
a strong chemical oxidant under
specified conditions, i. e., Dichromate,
50% sulfuric acid and 145°C for 2 hours.
&
OLIFORM GROUP - A group of bacteria
that inhabits tha intestinal tract of
man, warm-blooded animals, and
may be found in plants, soil, air and
47-4
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Glossary - Wastewater Treatment Technology
the aquatic environment. Includes
aerobic and facultative gram negative
non-spore forming bacilli that ferment
lactose with gas formation.
COLLECTION SYSTEM - The sewerage
collection system is comprised of the
conduits controlled by public agencies
to intercept house, commercial or
industrial discharges and transport
them to a treatment facility or dis-
charge point.
-^•COLLOID, COLLOIDAL STATE - A state
of suspension in which the particulate
or insoluble material is in a finely
divided form that reamins dispersed
in the liquid for extended time periods.
Usually cloudy or turbid suspensions
requiring flocculation before clarifi-
cation.
COMBINED AVAILABLE CHLORINE -
Generally refers to chlorine-ammonia
compounds exhibiting a slower reaction
with ortho tolidine, determinable with
phenyl arsene oxide after addition of
potassium iodide under acid conditions
and usually requires higher concentra-
tion and longer time to kill in com-
parison with free available chlorine.
COMBINED SEWER - A sewer designed to
carry wastewaters and storm waters
in the same channel.
COMBINED SEWAGE - Consists of house-
hold, commercial or industrial wastes
in combination with roof and surface
storm drainage.
COMMINUTION -
a) The act of cutting and screening
materials contained in wastewaters.
b) To reduce the size of fibrous or
amorphous materials.
COMMINUTOR - A device for cutting sew-
age solids until they pass through an
acceptable screen opening to improve
pumping and wastewater processing.
COMPOUND -
a) A combination of two or more atoms
having definite physical and chemical
characteristics and mutually attracted
to each other.
b) Atoms in the elemental state are
electrically neutral but the number
of external electrons may be increased
or decreased in response to conditions
and nature of the atom. An atom that
becomes electrically charged may
combine with another atom of opposite
charge to form an electrically neutral
compound.
CONCENTRATION -
a) The act of increasing the mass
per unit volume of one substance
with respect to another, such as
concentrating the solids in a sludge
from 37c to 6%.
b) A means of designating the ratio
of one substance with respect to
another, such as 15 mg of suspended
solids per liter of water.
CONDITIONING - An action of improving
possibilities for subsequent process-
ing such as chemical treatment to im-
prove sludge dewatering or filtering
CONING - A condition inaclarifier sludge
hopper where the solids concentrate
or sludge is partially withdrawn to
form a cone or channel through which
clarified liquid is pumped out while
most of the solids remain behind
around the cone. Infrequent sludge
pumping tends to encourage this
condition where the sludge tends to
solidify and is resistant to fluid flow.
CONTAMINATION - A general term re-
ferring to the introduction of materials
into water that make the water less
desirable for its intended use. Also
introduction of undesired substances
into air, solutions, or other defined
. media (chemical or biological)
-Vfc-CRITERION (pi. CRITERIA) - Something
which can be measured. Commonly
used as a basis for standards.
CROSS CONNECTION - In plumbing, a
physical connectionbetween two dif-
ferent water systems, such as be-
tween potable and polluted water lines
-^-CUBIC FOOT PER SECOND (c. f. s.) -
A unit of discharge rate such as
one cubic foot of gas per second
past a given point.
47-5
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CURVE -
a) A graphic plotted to represent
changes in value of one quantity in
reference to another.
b) A deviation from a straight line
without a sharp break or angularity.
DATA - Records of observations or
measurements of facts, occurrences
and conditions in written, graphical
or tabular form.
DEBRIS -
a) The remains of something broken
down or destroyed.
b) An accumulation of fragments of
rocks.
DECAY -
a) To undergo decomposition.
b) Implies a slow change from a state
of soundness or perfection.
c) To decay.
DEGRADE - To reduce the complexity of
a chemical compound
DE IONIZED WATER - Water that has been
treated by ion exchange resins or com-
pounds to remove cations and anions
present in the form of dissolved salts.
-Xdenitrification -
a) The conversion of oxidized nitrogen
(nitrate and nitrite-N) to nitrogen gas
by contact with septic wastewater solids
or other reducing chemicals.
b) A reduction process with respect
to oxidized nitrogen.
DETENTION PERIOD - The theoretical
time required to displace the entire
volume of a tank or basin at a given
rate of discharge. Tank volume -
rate of discharge
DETENTION PERIOD, ACTUAL - The
actual time required for a given unit
of liquid to flow through the tank or
process unit. Usually determined
by tracer method and depends upon
inlet and outlet geometry, temperature,
specific gravity, stratification, and
other factors.
DETERGENT - Something used for clean-
ing. Commonly consists of soap or
surfactant plus various additives or
associated materials.
DETRITUS - The heavier material moved
by natural flow, usually along the
channel bed. Sand, grit or other
coarse material.
DIAPHRAGM PUMP - A pump consisting
of a rubber diaphragm (generally)
fastened to a cylindrical casing
having inlet and outlet valves. When
the diaphragm is raised, liquid
enters to be forced out the discharge
valve on the reverse stroke.
DIFFUSED AERATION - Aeration pro-
duced by introducing air through a
dispersing mechanism into a liquid.
Sufficient air pressure must be
applied to overcome hydrostatic head
and diffusor or pipe back pressure.
"^¦DIFFUSOR - A porous plate, tube, bag,
or other device, through which air
is forced into a liquid in the form
of small bubbles.
T^DIGESTED SLUDGE - Solids concentrates
stabilized under aerobic or anaerobic
conditions to preferentially decompose
the more unstable fractions and pro-
duce a residue of satisfactory disposal
characteristics. To reduce the
volatile fraction of the sludge.
DILUTION -
a) To make thinner or more liquid.
b) A ratio, volume or weight of a
more concentrated sample or effluent
flow compared to that into which it
is discharged.
^-DISINFECTION -
a) To make free of infectious
organisms
b) To kill disease organisms.
DISPOSAL -
a) The discarding or throwing away.
b) For wastewaters, this may repre-
sent any method of disposing, but
usually involves some degree of
degradation and discard in a non-
pollutional manner.
47-6
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Glossary - Wastewater Treatment Technology
DISSOLVED -
a) Those materials dispersed in water
in ionic, atomic, or molecular form,
an homogenous mixture or solution
b) Generally clear but may be colored.
c) Present in true solution form.
-^DISSOLVED OXYGEN (D. O. ) - Dissolved
molecular oxygen usually expressed
in mg DO/1 or percent of saturation.
DISTILLED WATER - A purified water
resulting from heat vaporization
followed later by vapor condensation
to separate the water from non-
volatile impurities.
DISTRIBUTOR -
a) A device to control flow into some
desired direction or place.
b) A device used to spread the flow
evenly across a trickling filter surface
or other process unit.
DIVERSION CHAMBER - A basin or tank
that may be used to divert part of the
flow from a channel. May or may not
contain treatment capabilities or a
means of returning the diverted flow
to the treatment plant when a shock
load has passed.
DOSING SIPHON - A device to permit inter-
mittent dosing , such as for a trickling
filter. Consists of a chamber that will
fill gradually to a fixed level before
starting a siphon that permits rapid
drainage to the filter or other treat-
ment unit.
DRAINAGE TILE (Filter, or bottom tile) -
A vitrified tile underdrainage system
laid on the bottom to support trickling
filter stone, sand, or other filter
media, including sludge drying beds.
These are specially prepared blocks
or half-tiles containing slots for
passage of water or air but restricting
bed media penetration.
DRYING - The removal of water by natural
or engineered means.
DYNAMIC HEAD, TOTAL - The difference
in pressure at the elevation of the
pump discharge and the elevation at
the pump suction flange, plus the
velocity head at the discharge minus
the velocity head at the suction flange,
all corrected to the same units and
datum points.
ECOLOGY' - The relation of an organism
to its environment, 1. e. , how is an
organism affected by his surround-
ings such as air, water, heat, noise,
contamination, etc.
EFFICIENCY - The ratio of materials
out of a process to those into that
process usually expressed as a
percentage.
EFFLUENT - A liquid or product water
discharged from a chamber, basin
or other treatment operation.
ELEMENT -
a) Elementary substance.
b) A substance or kind of matter
in which all atoms are alike in that
they will have the same average
relative weight and the same number
of external electrons.
-^-ELUTRIATION - A washing operation.
Sludge elutriation is an action where
digested or process sludge is washed
with sewage or effluent to remove
fine particulates or eertain soluble
components. The elutriate is re-
cycled to process waters, the elu-
triated solids are more readily
filtered.
ENDOGENOUS METABOLISM - A dimin-
ished level of metabolism in which
various materials previously stored
by the cells are oxidized.
-^ENTERIC ORGANISMS - Those organisms
commonly associated with the in-
testinal tract.
ENTRAINMENT - A condition or action
that will cause an immiscible sub-
stance to be mixed with another.
Usually the result of turbulence or
entrapment, 1, e., air bubbles in
aqueous media.
ENZYME - A soluble or colloidal organic
catalyst produced by a living organ-
ism. Usually they are simple or
conjugated proteins that catalyze
specific reactions.
EQUIVALENT -
a) Equal in force, amount, or value.
b) Chemical The atomic or molec-
ular weight of one substance that will
react with one unit of weight of another
substance, 1 e., that weight of an
47-7
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Glossary - Wastewater Treatment Technology
alkali necessary to precisely equalize
1 gram atomic wt. of H+ion.
EUTROPHLC - Well nourished, rich in dis-
solved nutrients.
^-EUTROPHICATION - An action involving
the aging of lakes characterized by
nutrient enrichment and increasing
growth of plant and animal organisms.
The net effect is to decrease depth
until the lake becomes a bog and
eventually dry land. Man-made pol-
lution tends to hasten the process.
-^FACULTATIVE BACTERIA - Bacteria
that can adapt themselves to growth
and metabolism under aerobic or
anaerobic conditions. Many organ-
isms of interest in wastewater
stabilization are among this group.
FAHRENHEIT - A temperature scale in
which pure water at sea level has
a freezing point at 32 ° and the
boiling point is 212 °.
FATS - Naturally occurring compounds
functioning as storage products in
the living organisms. Consist of
carbon, hydrogen and oxygen in the
form of fatty acid esters. Generally
semi-solid or oily at normal temper-
atures.
ECAL COLIFORM - A group of organisms
belonging to the coliform group and
whose presence denotes recent fecal
pollution from warm-blooded animals.
Standard tests are available to differ-
entiate the fecal coliform group from
the other members of the group which
have a lesser sanitary significance.
FERMENTATION - A form of respiration
by organisms which requires little or
no free oxygen, yielding alcohol and
carbon dioxide as end products and
releasing only part of the food energy
available, l e. , the conversion of
sugars into alcohol by enzymes from
yeasts.
FILTER - A porous media through which
a liquid may be passed to effect re-
moval of suspended materials. Filter
media may include paper, cloth, sand,
prepared membranes, gravel, as-
bestos fiber, or other granular or
fibrous material.
FILTER CLOTH - Fabric, wire or other
material stretched over the drum
of a vacuum filter and accessories
to support the solids during cake
formation and discharge the solids
when and where desired.
FILTER FLOODING - The filling of a
trickling filter with liquid to a level
above the media by closing all out-
let parts. Generally to control
nuisance orgamsms such as flies.
FILTER FLY - Small black flies commonly
found in or near the trickling filter.
Commonly the Psychoda group.
FILTER LOADING - The mass (or volume)
of applied oxygen demand or solids
per unit of filter area or volume.
See load ratio.
FILTER MEDIUM - Any material over
which water sewage or other liquid
is passed for purification purposes
by chemical, biological or physical
processes.
FILTER PONDING or CLOGGING - The
effect of fine particles on sand
filters or organic growth on trick-
ling filters that restricts normal
passage of liquid through the filter
as a result of filling void spaces.
FILTER RESIDUE - That material which
is retained on or in a filter.
FILTER UNLOADING - A phenomenon
in which normally attached growth
or slime on trickling filter media
becomes detached and either par-
tially or completely sloughs off
FILTRATE - That liquid which has
passed through a filter.
FILTRATION RATE - A rate of applica-
tion of water or wastewater to a
filter. Commonly expressed in
million gallons per acre per day
or gallons per square foot per min.
FINAL SETTLER, CLARIFIER - A
settling basin or chamber for the
mixed liquor following secondary
treatment.
FLAME ARRESTOR - A safety device
in the handling of flammable gases.
Usually consists of an enlargement
in a pipe line containing a metallic
47-8
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Glossary - Wastewater Treatment Technology
grid that allows passage of gas but
acts as a barrier to the passage of
flame.
FLIGHTS - A cross member of a conveyor
system used for collection and trans-
port of the collected material, 1. e.,
the boards fastened to a chain loop
on either side of a primary clarifier
that pushes scum along the surface
to a collector trough and sludge along
the bottom to the sludge collector.
FLOAT CONTROL - Commonly a device
to control a pump or pumps according
to the water level in a chamber or
well as indicated by the float. Usually
operates a relay to control pump power,
number, or speed of pumps in operation.
FLOATATION - A process for separation
of solids from clarified liquid that
causes particulates to be floated to
the surface by means of attached air
globules.
FLOATING COVER - A gas tight cover
with a water seal supported by digester
gas pressure and capable of moving
upward or downward with liquid and
gas content of the digester.
-^FLOC - Gelatinous or amorphous solids
formed by chemical, biological or
physical agglomeration of fine ma-
terials into larger masses that are
more readily separated from the liquid.
FLOCCULATION - The gathering together
of fine particulate materials in a sus-
pension to form loosely associated
larger masses of solids agglomerates.
jW'LUME - A long narrow channel for gravity
™ flow of liquid from one point to another.
FLY AWAY BOD - Wastewater stabilization
operations such as trickling filters en-
courage the development of insect larvae
that serve as scavengers during their
development If the adult form of the
larvae have functionable wings, the
equivalent of oxygen demand consumed
during development becomes fly-away
BOD.
^FREE AVAILABLE CHLORINE - Generally
includes that chlorine existing in water
as the hypochlorous acid. Character-
tiOCJ.* ized by rapid color formation with
' ortho tolidine. Can be titrated in
neutral solution with phenyl arsene
oxide and produces a rapid organism
kill in low concentrations.
FREE BOARD - The vertical distance
from the normal water level in a
flume, conduit, channel, basin, or
other water enclosure, to the top
of the confining structure.
-^FRESH SLUDGE - Recently deposited
sludge from sedimentation tanks
that nas not been conditioned,
processed, or progressed mater-
ially into the anaerobic action stage.
*
FUNGI - Simple or complex organisms
without chlorophyll. The simpler
forms are one-celled, higher forms
have branched filaments and com-
plicated life cycles. Examples are
molds, yeasts and mushrooms.
- Federal Water Pollution Control
Administration, U S. Department of
the Interior.
GAS DOME - A chamber usually mounted
on top of the digester cover for
separation of gas from scum, foam
or liquid.
GAS HOLDER - A tank used for storage
of gas from sludge digestion units
for the purpose of meeting the gas
demand for burners, engines, or
other use during non-steady pro-
duction or use periods.
GATE CHAMBER or GATE HOUSE -
A chamber installed for housing
devices for controlling flow to
various parts of a collection, treat-
ment or distribution system,
including valves, gates, and auto-
matic or manual controls.
GAUGE -
a) The action of measuring some
item such as flow, level, size,
rate, etc.
b) A device for gauging.
c) A size designation or indicator
for some definite item such as 20-
gauge wire, 16-gauge sheet steel
GERMICIDE - An agent that kills micro-
organisms
47-9
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Glossary - Wastewater Treatment Technology
GRAVITY SYSTEM - A system of open or
closed conduits in which the liquid
flows by gravity (without pumping).
GRIT - The heavy material in water or
sewage" such as sand, gravel, cinders,
etc.
-^GRIT CHAMBER - An enlargement of a
channel designed to reduce flow ve-
locity adequately to permit differential
separation of sand or grit from organic
suspended material. Usually approaches
a linear flow velocity of 1 to 3 ft/ sec.
GRIT COLLECTOR - A device placed in a
grit chamber to collect and to convey
the more coarse and dense grit parti-
cles out of the chamber and permit
return of most of the organic or liquid
materials.
¦^HARDNESS - Commonly refers to the
chemicals interfering with soap action
or producing scale in boilers or
heating units. Specifically refers to
Calcium and Magnesium salts, some-
times including Iron, aluminum, and
silica.
HEAD LOSS - The difference in pressure
between the inlet and outlet pressure
of a given process unit arising as a
result of flow resistance within the
process unit, such as the head loss
due to friction of a filter media and
filter residue.
HEAT EXCHANGER COILS - A piping lay-
out designed to circulate a liquid media
within the contents of the process unit
but without mixing with the process
media for the purpose of adding or re-
moving heat, i. e., hot liquids may be
circulated within a digester to raise
digester temperature.
HUMUS - A brown or black complex and
variable material resulting from de-
composition of plant or animal matter.
HYDROLYSIS - The addition of water to
any chemical compound. Commonly
involved in splitting complex sub-
stances by addition of water to form
more simple compounds.
HYDROSTATIC HEAD - The pressure
exerted by a given height of liquid
above a given datum point. May be
listed in feet of head, pounds per
square inch, or other criteria.
IMPELLER - A rotating set of vanes to
impart motion to a fluid, commonly
within a casing where dynamic energy
of fluid increases from the center
to the tip of the vanes. May be closed
or open depending on a tube or paddle
configuration.
^¦IMHOFF CONE - A conical glass container
commonly one liter capacity, having
the upper larger diameter end open
and the closed apex downward with
graduations to assist estimation of
the volume of settleable solids after
an arbitrary time interval for set-
tling (usually one hour).
"¦^-IMHOFF TANK - A deep two-story tank
originally patented by Karl Imhoff.
The floor of the upper chamber is
s lotted for transfer of settleable
solids from the settling chamber.
The lower chamber serves for an-
aerobic digestion and storage of
solids.
INDICATOR - May include the color change
of a dye, electronic sensor response,
or other means of estimating the
equivalence point of a reaction be-
tween two different materials.
INFILTRATION -
a) The entrance of ground water into
a sewer through breaks, defective
joints, or porous walls.
b) The penetration of water through
the soil from surface precipitation,
stream or impoundment boundaries.
-^INFLUENT - That material entering a
process unit or operation.
INORGANIC - Being composed of material
other than plant or animal materials.
Forming or belonging to the inanimate
world.
INTERCEPTOR - An intercepting sewer
designed to carry the dry weather
flow from a community to a treatment
plant, but not large enough to carry
storm water above some preset ratio
to dry weather flow. May be used
to collect lateral sewer flows.
47-10
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Glossary - Wastewater Treatment Technology
LA GOON - A natural or artificial basin used
^ for storage and/or stabilization of
wastewater or sludge. Sometimes
used for indefinite storage for dis-
posal purposes. Commonly the lagoon
depth is greater than a wadable depth
but not greater than twenty feet.
LATERAL SEWER - A sewer that dis-
charges into a branch or main sewer
and has no other tributaries other
than individual house connections.
LIQUID SLUDGE - An organic solids con-
centrate usually formed by deposition
from wastewaters. The water content
varies with the origin and nature of
the sludge, usually has enough water
to permit pumping but does not contain
significant separatable free water.
LOAD - The load to a process is that which
is contained in the inflow to that process.
It may be expressed as hydraulic,
oxygen demand, solids, or other
criteria.
LOAD RATIO - An index of loading, in-
cluding mass input per unit of capacity
per unit of time. Mass may be ex-
pressed in lbs., BOD, COD, Susp.
or volatile solids, capacity in volume,
weight of solids or volatile solids in
process,and time,usually in days.
LYSIS - To decompose, loosen, or separate
into component parts.
MANHOLE - An opening by which access
may be achieved for inspection,
madntenance, or repair of a sewer,
conduit, or other buried structure
or appurtenance.
MANOMETER - An instrument for measuring
pressure. Usually consists of a U-
shaped tube containing a liquid, the
surface of which moves proportionally
in one open end with changes in
pressure exerted upon the other end.
MECHANICAL AERATION - Aeration
produced by mechanical energy of
the turbine, pump, paddle, or other
device that imparts an intimate mix-
ture of liquid and air.
^MEMBRANE FILTER - A flat, highlyporous
flexible plastic disc, commonly about
0.15 mm in thickness and 47-50 mm in
diameter. Membrane filters having
a pore size of 0. 45^ are used in
water microbiology to trap organisms,
and,by use of standard media and
conditions, direct enumeration by
colony count of selected organisms.
MENISCUS - The curved upper surface
of a liquid in a tube that is concave
upward when the containing walls
are wetted by the confined liquid »
and convex upward when they are not.
MESOPHILLIC - Medium temperature
loving. Organisms capable of opti-
mum metabolic activities at temper-
atures from about 80°-110°F, 26"-
42°C.
METER - The length of a reference
platinum bar used as a standard
unit of measurement of length in
the metric system, 1 meter =
39. 37 inches.
MICRO - 1/1, 000, 000 of a unit of measure-
ment, such as microgram, microliter.
MICROBIOLOGY - The science and study
of microbiological organisms and
their behavior. Commonly related
to the study of pathogenic organisms.
^^MICROORGANISM - Commonly an organ-
ism too small to be observed indi-
vidually by the human eye without
optical aid.
MILLI- - An expression used to indicate
1/1000 of a standard unit of weight,
length or capacity (metric system).
Milliliter (ml) 1/1000 liter (1)
Milligram (mg) 1/ 1000 gram (g)
Millimeter (mm) 1/1000 meter (m)
MILLI EQUIVALENT WEIGHT - 1/1000
of the equivalent weight, usually
expressed in milligrams (mg)
MG/ L - A unit of concentration on a
weight/ volume basis: Milligrams
per liter. Equivalent to ppm when
the specific gravity of the liquid is
1. 0.
-^^"MIXED LIQUOR - A mixture of return
sludge and wastewater in the aerator
of an activated sludge plant. Also
may be used in reference to mixed
aerobic or anaerobic digesters
47-11
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Glossary - Wastewater Treatment Technology
MIXING ZONE - An area where two or more
substances of different characteristics
blend to form a uniform mixture, i. e. ,
chlorine application, heated water, or
other discharged materials entering a
water mass will show significant dif-
ferences of chlorine residual, tem-
perature or other criteria, depending
upon the sampling location throughout
the mixing zone and approach uniform
results with respect to lateral,longi-
tudinal,and vertical sampling positions
when mixing has been completed.
MOISTURE CONTENT - The content of
water in some other material. Com-
monly expressed in percentage of
moisture in soil, sludge or screenings.
-^(¦MOST PROBABLE NUMBER (MPN) - A
statistical method of determining
microbial populations. A multiple
dilution tube technique is utilized
with a standard medium and observa-
tions are made for specific individual
tube effects. Resultant coding is
translated by mathematical probability
tables into population numbers.
"^¦NITRIFICATION - Ths biochemical con-
version oT unoxidized nitrogen
(ammonia and organic N) to oxidized
mtrogen (usually nitrate).
NORMALITY -
a) A means of expressing ths concen-
tration of a standard solution in terms
of the gram equivalents of reacting
substances per liter.
b) Generally expressed as a decimal
fraction, such as 0. 1 or 0. 02 N.
"^NUTRIENTS -
a) Anything essential to support life.
c) Nitrogen and phosphorus are of
major concern because they tend to
recycle and are hard to control
ODOR CONTROL - In wastewater treatment
this generally refers to good house-
keeping in the plant and aeration,
chlorination or other operations to
prevent onset of malodorous septicity
in the wastewater flow
OILS -
a) Liquid fats of animal or vegetable
origin
b) Oily or waxy mineral oils.
ORGANIC - Substances formed as a result
of living plant or animal organisms.
Generally contain carbon as a major
constituent.
ORGANIC CHLORINE - Compounds con-
taining chlorine in combination with
carbon, hydrogen and certain other
elements.
ORIFICE METER - A device consisting
of a flange set in a pipe section
containing an opening smaller than
the pipe. Pressure readings above
and oelow the orifice may be related
to flow.
"^ORTHO TOLIDINE CHLORINE TEST -
The dye, ortho tolidine, under highly
acid conditions, produces a yellow
color proportional in intensity to the
concentration of available residual
chlorine and certain other oxidants
or interfering materials.
OUTFALL SEWER - The outlet or channel
through which sewage effluent is dis-
charged.
OXIDATION - Chemically: The addition
of oxygen, removal of hydrogen, or
the removal of electrons from an
element or compound.
OXIDATION POND - A shallow basin
employed for the stabilization of
wastewaters.
OXYGEN AVAILABLE - That part of the
oxygen available for aerobic stabil-
ization of organic matter. Includes
dissolved oxygen and that available
in nitrite or nitrates, peroxides,
ozone, and certain other forms of
oxygen.
OXYGEN BALANCE - Refers to the dy-
namic relationship among ths avail-
able oxygen assets and the oxygen
requirements for stabilization of
oxygen demanding materials in a
treatment plant or receiving water.
b) Includes many common elements
and combinations of them The major
n.itrients include carbon, hydrogen,
oxygen, nitrogen, sulfur, and phosphorus.
47-12
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Glossary - Wastewater Treatment Technology
OXYGEN DEPLETION - The loss of oxygen
from water or sewage due to biological,
chemical or physical action.
PARASITE - A living organism deriving its
nutrients at the expense of another
living organism, giving nothing in re-
turn.
PARSHALL FLUME - A device for estima-
tion of the flow in an open conduit.
Consists of a constricting section,
a throat, and an expanding section.
The throat contains a sill over which
the liquid passes. The pressure
change over the sill can be related
to quantity of flow.
PARTICULATE MATERIAL - Refers to
detectable solid material dispersed
in a gas or liquid. Small sized par-
ticulates may produce a smoky or hazy
appearance in a gas, milky or turbid
appearance in a liquid. Larger partic-
ulates are more readily detected and
separated by sedimentation or filtration.
PARTICULATES - Pertaining to small sus-
pended solids in a gaseous or liquid media.
-^PARTS PER MILLION (PPM) - A unit of
concentration signifying parts of some
substance per million parts of dis-
persing medium. Equivalent numer-
ically to mg/1 only when the specific
gravity of the solution is 1.0.
PATHOGENIC ORGANISMS - Bacterial,
fungal, viral, or other organisms
directly involved with diseases of
plants, animals, or man, are in-
cluded among this group.
PERCENTAGE TREATMENT - The ratio
expressed as a percentage of the
material removed from process water
in terms of the material entering.
Sometimes referred to as reduction.
-^PH - An index of hydrogen ion activity.
Defined as the negative logarithm
(base 10) of H ion concentration at
a given instant. On a scale ofO to 14
pH 7. 0 is neutral, pH less than 7. 0
indicates a predominance of H+ or
acid ions, pH greater than 7. 0 indi-
cates a predominance of OH" or
alkaline ions.
PNEUMATIC EJECTOR - A device for
pumping sludge, sewage, or other
liquid by admitting the fluid into a
chamber through one check valve
and forcing it out of another by air
pressure in the chamber above the
liquid.
¦^.POLLUTION - Anything appearing in water
that renders it unacceptable in terms
of established water quality standards.
Commonly conditions or contaminants
that interfere with subsequent bene-
ficial uses of the water.
POND - A basin or catchment used for
retention of water for equalization,
stabilization, or other purposes.
Commonly less than five feet in depth.
PONDING - With reference to trickling
filtration, ponding refers to a plugging
of the filter media by slimes or solids
to restrict downward movement of
wastewater sufficiently to cause sur-
face accumulation of liquid either
partially or completely.
PRECIPITATE - The formation of solid
particles in a solution, or the solids
that settle as a result of chemical
or physical action that caused solids
suspension from solution.
PRESSURE - The total load or force acting
upon a surface. In hydraulics, the
term commonly means pounds per
square inch of surface, or kilograms
per square cm above atmospheric
pressure on site. (Atmospheric
pressure at sea level is about 14. 7
pounds per square inch. )
PRIMARY SLUDGE - Sludge obtained
from a primary sedimentation tank.
-V-PRIMARY TREATMENT - Commonly the
' separation of settleable or floatable
materials from carrier water.
Usually preceded by pretreatment
such as coarse screens, grit sep-
aration, comminution.
PROCESS - A series of operations or
actions that lead to a particular
result. A combination of unit oper-
ations that may be assembled and
used for a given treatment objective.
47-13
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Glossary - Wastewater Treatment Technology
PROTEINS - Naturally occurring compounds
containing carbon, hydrogen, nitrogen,
and oxygen, with smaller amounts of
sulfur and phosphorus, and trace com-
ponents essential to the living cells.
An essential food associated with
meat and eggs.
¦^PROTOZOA - Single cell or multiple cell
organisms, such as amoeba, celiates,
and flagellates. Commonly aquatic
and generally derive most of their
nutrition from preformed organic food.
PSYCHROPHILLIC ORGANISMS - Low
temperature loving organisms, or
having a competitive advantage
over other organisms at lower tem-
peratures; i.e. , from about 10°C
downward to the freezing point.
"^•PUTREFACTION - Biological decomposition
of organic matter with the formation
of ill-smelling products, such as H2S,
amines, mercaptans. Associated with
anaerobic conditions.
QUIESCENT - Characterized by a lack of
or negligible movement of the sus-
pending media, such as liquid or gas.
Still or absence of turbulence.
^•RAW WASTEWATER (SEWAGE) - Used
wastewater prior to treatment.
RECIPROCATING PUMP - A pump device
using a piston within a casing fitted
with suction and discharge valves.
Movement of the piston in one direction
fills the casing, the reverse movement
forces liquid into the discharge line.
May be vertical or horizontal.
RECIRCULATION - The return of effluent
to the influent of a process unit to
reduce influent concentration, sta-
bilize the system, maintain hydraulic
flow, to reprocess; or for other bene-
ficial reasons.
RECORDER -
a) A device to keep a continuous or
intermittent record of some measured
item such as flow, velocity, applied
power, etc.
b) An individual who tabulates or
maintains records of events, actions
or measurements.
REDUCTION -
a) To make smaller or to remove
from a given amount of material
b) Chemistry: The removal of
oxygen, addition of hydrogen, or
the addition of electrons to an ele-
ment or compound.
RELIEF SEWER - A sewer built to carry
the flow in excess of the capacity of
an existing sewer.
RESIDUAL CHLORINE - See Available
Residual Chlorine.
RETURN SLUDGE - Sludge returned from
process to the influent flow. Com-
monly return activated sludge from
a secondary clarifier. Also may
include sludge from a clarifier after
trickling filtration.
ROTARY DISTRIBUTOR - A device usually
mounted on a center post with hori-
zontal arms extending to the edge of
a circular trickling filter for distri-
bution of flow over the entire bed
surface.
SALT - A chemical compound formed as
a result of the interaction of an acid
and an alkali (base). The common-
est salt is sodium chloride formed
from hydrochloric acid and sodium
hydroxide. This ionizes in water
solution to form Na+ and Cl~.
SANITARY SEWER - A sewer designed
to receive and to convey household,
commercial or industrial waste-
water mixtures.
SAPROBIC, SAPROPHYTIC - Organisms
living upon dead or decaying organic
matter. Organisms that utilize non-
living organic matter as a food.
SATURATION - Commonly refers to the
maximum amount of any material
that can be dissolved in water or
other liquid at a given temperature
and pressure. For oxygen, this
commonly refers to a percentage
saturation in terms of the saturation
value, such as about 9 mg Oo/l at
20° C.
47-14
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Glossary - Wastewater Treatment Technology
SCAVENGERS - Organisms that feed
habitually upon refuse or carrion.
In water pollution, this commonly
refers to worms, insect larvae,
bloodworms, sow bugs, and crusta-
ceans. Or, more properly, oligo-
chaetes, chironomids and isopods.
SCREEN - A device with openings, gener-
ally having a relatively uniform size,
that permit liquid to pass but retain
larger particles. The screen may
consist of bars, coarse to fine wire,
rods, gratings, paper, membranes,
etc., depending upon particle size
to be retained.
SCREENINGS - Material removed by the
screens.
SCUM BOARD - A vertical baffle, above
and below the liquid surface of a basin
or tank, designed to prevent the
passage of or to contain floating
material within designated limits.
SCUM BREAKER - A device installed in a
sludge digestion tank to disperse sur-
face accumulations. Generally
accomplished by means of mechanical
agitation, gas or liquid recirculation,
to promote mixing and destratification.
SCUM COLLECTOR - A mechanical device
for skimming and removing scum or
floatable material from the surface
of a tank.
SECOND FOOT - An abbreviation for
cubic foot per second. A rate term.
-^SECONDARY TREATMENT - Processes
used to convert dissolved and colloidal
materials in wastewater to a form that
may be separated from the water.
Commonly consists of biodegradation
and conversion to cell mass in a
separatable form with partial oxida-
tion, such as in activated sludge,
trickling filtration, or oxidation ponds.
SEDIMENTATION - The process of subsi-
dence and deposition of suspended
matter from wastewater by gravity.
Also called clarification, settling.
SEPTIC SLUDGE - That sludge which has
reached a stage of anaerobic putre-
faction (sulfate reduction). Includes
that from Imhoff, septic, or sludge
digestion tanks.
EPTIC WASTEWATER (SEWAGE) -
Wastewater in which available oxy-
gen has been depleted and the
reduction of sulfates has begun. A
result of anaerobic putrefaction.
jyL SETTLEABLE SOLIDS -
a) Includes materials that will settle
by gravity under low flow velocities.
b) Commonly expressed in terms
of the volume of solids accumulating
in an Imhoff cone after one hour on
a volume basis.
SETTLING BASIN - A natural or engineered
enlargement of a channel that reduces
velocity sufficiently to permit sedi-
mentation of settleable particulates.
SEWAGE - See Wastewater.
SEW AGE GAS, DIGESTER GAS - The gas
produced from anaerobic (septic)
sewage solids. Generally contains
marsh gas (methane) and carbon
dioxide with hydrogen sulfide and
other components in minor propor-
tions.
SEWER - A pipe or conduit,generally
covered if or the purposes of con-
veying wastewaters from the point
of origin to a point of treatment or
discharge.
SEWERAGE SYSTEM - A system of
sewers and appurtenances for the
collection, transportation and
pumping of used waters for a given
area or basin. Any treatment de-
vice or facility and its outfall con-
duit are a part of the system.
SHORT CIRCUITING - Hydraulic- A con-
dition in which one part or unit of
flow into the basin reaches the outlet
in much less time than that required
for a uniformly mixed flow.
Electrical: A situation in which an
electric current is out of place in
relation to its controlled pathway.
SLIME - SEWAGE SLIMES - Consisting
of organisms growing on wastewater
nutrients with the formation of mu-
cilaginous covering, streamers or
clumps. May consist of bacteria,
molds, protozoa or algae.
47-15
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Glossary - Wastewater Treatment Technology
"^SLOUGHING - A phenomenon associated
with trickling filters and contact
aeration units where slimes build up
to a varying degree, then slip off
into the effluent.
"^SLUDGE - Accumulated or concentrated
solids from sedimentation or clari-
fication of wastewater. Contains
varying proportions of solids in
wastewater depending upon source,
process, and nature.
SLUDGE BANKS - An accumulation of solids
including silt, mineral, organic, and
cell mass particulate material, that
is produced in the aquatic system
characterized by low current velocity,
Generally refers to gross deposits of
appreciable depth.
SLUDGE CAKE - The solids remaining
after dewatering sludge by vacuum,
filtration, or sludge drying beds.
Usually forkable or spadable, with
a water content of 30 to 80%. Also
may occur on the boundaries of
surface water.
SLUDGE COLLECTOR - A mechanical
device, including rake, drag, or
suction, for collecting settled sludge
from the bottom of a clarifier into a
sump or other withdrawal system.
SLUDGE DIGESTION - A process by which
organic matter in sludge is converted
into more stable or separatable form
through the action of living organisms.
May be the result of aerobic or an-
aerobic digestion.
SLUDGE DRYING BED - An area used to
discharge wet sludge for drainage
and drying. Generally prepared of
porous bed material surrounded by
sidewalls to contain the sludge while
the liquid percolates into an under-
drain system. May be covered or
uncovered.
SLUDGE FILTER - A device to effect
partial water removal from wet
sludge,usually with the aid of vacuum
or pressure of preconditioned sludge.
SLUDGE SYNTHESIS - The net gain in
sludge mass in a process over a
period of time as a result of simul-
taneous growth of cell mass and
endogenous oxidation within it.
SLUICE GATE - A gate constructed for
adjustment to control the flow in a
channel by gate position.
SOLUTION -
a) An homogenous mixture, commonly
gas, liquid, or solid in a liquid that
remains clear indefinitely.
b) Generally an atomic, ionic, or
molecular dispersion in a liquid (may
be colored).
c) A water solution of dissolved
material.
SPECIFIC GRAVITY (Sp. Gr.) -
a) The weight of a material per unit
volume in reference to the weight
of water at maximum density.
b) Water at 4°C has a weight of lg
per ml. The weight ratio of any
substance divided by the weight of
water is the specific gravity.
SQUEEGEE -
a) A device, generally rubber, used
for dislodging and removing solids*
scum or other materials from a
surface.
b) Metal or wood blades to move
sludge solids along the bottom of
a clarifier.
STABILITY -
a) The ability of any substance to
resist putrefaction.
b) Ability of an engineered structure
to resist distortion or overturn when
loaded.
STABILIZATION -
a) The activity proceeding along the
pathway to stability.
b) In organic wastes, generally
refers to oxidation via biochemical
pathways and conversion to gaseous
or insoluble materials relatively
inert to further change.
-^STANDARD - Something set by authority.
Having qualities or attributes re-
quired by law and defined by mini-
mum or maximum limits of accept-
ability in terms of established
criteria or measurable indices.
47-16
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Glossary - Wastewater Treatment Technology
-^STANDARD METHODS - Methods of analysis
prescribed by joint action of APHA,
ASCE, AWWA, and FWPCA. Methods
accepted by authority.
STEP AERATION - A procedure for adding
increments of wastewater at various
points along the line of flow in an
activated sludge aerator.
STERILIZATION - The process of making
a medium free of living organisms
such as by killing them, filtering
through a porous medium fine enough
to be a barrier to the passage of
organisms, etc.
STORM OVERFLOW - A device such as a
weir, dam, or orifice, in a combined
sewer that will intercept design flow
but permit excess storm flow to dis-
charge directly. The overflow con-
tains a mixed discharge of storm and
other sewer components.
STORM SEWER - A sewer which carries
storm water from roofs, surface wash
and street drainage.
^STUCK DIGESTER - Any of a series of
events that results in serious mal-
function of the digester. Commonly
refers to anaerobic digestion where
overloading, temperature control,
toxicity, or other factors, result in
an excessive acid production with
serious limitations of gasification,
stabilization, and solids concentration.
SUBSTRATE -
a) The base or media in which an
organisms lives.
b) The liquid in an activated sludge
aeration tank.
-^-SUPERNATANT LIQUOR - The liquid over-
lying deposited sludge. Commonly
that fraction of liquid in an anaerobic
digester located over the deposited
material and beneath possible surface
floating material.
^SURFACTANT -
a) A chemical that, when added to
water, will greatly reduce the surface
tension of the solution.
b) The surface active component in
a detergent mixture.
-^-SUSPENDED SOT,TPS - The concentration
of insoluble materials suspended or
dispersed in waste or used water.
Generally expressed in mg/liter on
a dry weight basis. Usually deter-
mined by filtration methods.
SYNERGISM - Refers to the action pro-
duced when two or more substances
in combination have a greater effect
than that produced by the additive
effects of each one separately.
TAPERED AERATION - A procedure for
adjusting air input along the line of
flow of an activated sludge aerator
according to need. Usually requires
addition of more air per unit of
volume at the inlet end of the aerator.
^TERTIARY TREATMENT - See Advanced
Waste Treatment.
THERMAL POLLUTION - Refers to
heated discharges to surface water-
ways. The largest contributor of
heated discharges is associated
with power production.
THERMOPHILIC - High temperature
loving organisms. Generally con-
sidered to include organisms having
a favorable competitive advantage
at temperatures above 110°F or42°C.
THIEF - A term applied to a sampling
tube used to remove a core of
sample from a bag or bulk material.
-^TITRATION - The careful addition of a
' standard solution of known concen-
tration of reacting substance to an
equivalence point to estimate the
concentration of a desired material
in a sample.
-)fTOC - Total Organic Carbon. A test
expressing wastewater contaminant
concentration in terms of the car-
bon content.
-^¦TOTAL SOLIDS - Refers to the solids
contained in dissolved and suspended
form in water. Commonly deter-
mined on a weight basis by evapora-
tion to dryness.
47-17
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Glossary - Wastewater Treatment Technology
-^TRICKLING FILTER - A treatment process
employing downward flow of wastewater
over the surfaces of a rock or grid
system with a large void space for
upward movement of air. Slime
organisms accumulate to effect bio-
logical stabilization.
^¦UNIT OPERATION - A particular kind of
a physical change that is repeatedly
and frequently encountered as a step
in a process such as filtration,
aeration, evaporation, mixing, or
pumping.
UNITS OF MEASUREMENT -
English - foot, pound, second.
Metric - centimeter, gram, second.
Abbreviations: ft., lb., sec.
cm. , g. , sec.
USPHS - United States Public Health
Service, Department of Health,
Education and Welfare.
USPHS DRINKING WATER STANDARDS -
A list of standards prescribed for
potable water acceptable for use on
interstate carriers. Deal with
sources, protection, and bacterio-
logical, biological, chemical and
physical criteria—some mandatory,
some desired. Official for municipal
use only upon acceptance by State and
local authorities.
VELOCITY (FLOW) - A rate term expressed
in terms of linear movement per unit
of time. Commonly expressed in
ft per sec (English) or cm/sec (Metric).
VENTURI METER - A device for estimating
flow of fluid in closed conduits or pipes.
Generally based upon constricting and
enlarging pipe sections with pressure
at the full size and the point of maximum
constriction. Differences in pressure
can be related to flow.
"^VIRUS - A term generally used to designate
organisms that pass filtration media
capable of removing bacteria. Tech-
nically described as a collective term
covering disease stimuli held by some
to be living organisms and by others
to be nucleic acids capable of repro-
duction and growth.
^-VOLATILE ACIDS - A group of low molec-
ular weight acids such as acetic and
propionic, that are distillable from
acidified solution.
VOLATILE MATERIAL -
a) Refers to those chemicals having
a vapor pressure low enough to
evaporate from water readily at
normal temperatures.
b) With reference to dry solids, the
term includes loss in weight upon
ignition at 600°C.
""^^.VOLATILE SOLIDS - The quantity of
solids in water that represents a
loss in weight upon ignition at 600°C.
WASTEWATER - Refers to the used water
of a community. Generally contam-
inated by th'e waste products from
household, commercial or industrial
activities. Often contains surface
wash, storm water and infiltrations
water.
WASTE SLUDGE -
a) Commonly refers to activated
sludge produced in excess of that
required for return process.
b) Any solids concentrate to be
routed for disposal.
WATER QUALITY CRITERIA - Includes
selected analytical measurements
with limits designated to be accept-
able or unacceptable in reference
to water quality standards.
WATER QUALITY STANDARDS - Limits
set by authority on the basis of water
quality criteria required for bene-
ficial uses.
WEIR - A device used for surface over-
flow from a tank, basin or chamber.
Generally designed to smooth out
discharge flow to minimize turbu-
lence within the detention basin.
May be used to measure discharged
flow.
WEIR BOX - An enlargement of the
channel upstream of a weir to re-
duce the velocity and turbulence
before reaching the weir.
47-18
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Glossary - Wastewater Treatment Technology
WELL -
a) An artificial excavation or shaft
that collects water from interstices
of the soil or rock.
b) Also an engineered structure for
the housing of pumps or other equip-
ment below ground level.
WET OXIDATION - Oxidation of substances
such as organic contaminants in water
media. Includes biological oxidation
and physical chemical oxidation, such
as that obtained at elevated tempera-
ture, pressure .catalyst or other pro-
moters.
WPCF - Water Pollution Control Federation.
An organization composed of individuals
engaged in the advancement of knowledge
in research, design, operation, and
control of water pollution in relation
to man and his environment.
YIELD -
a) To give up or relinquish.
b) To bear or bring forth as a result
of cell division.
c) To produce as a result of invest-
ment of energy, materials, or time.
d) The amount or quantity produced
per unit of raw material.
YIELD FACTOR - A decimal fraction or
percentage of product per unit of input.
REFERENCES:
1 Any of the standard dictionaries.
2 Glossary, Water and Sewage Control
Engineering. APHA, ASCE,
AWWA, FSWA. (1969)
3 Glossary, Ohio Operator Training
Committee.
4 Jacobs, Morris B., Gerstein, Maurice J.,
and Walter, William G. Dictionary
of Microbiology. D. Van Nostrand,
Inc. (1957)
5 Rose, Arthur and Elizabeth. Condensed
Chemical Dictionary, 7th Ed. ,
Reinhold Publishing Co. (1961)
6 U. S. Dept. of Interior, Office of Water
Resources Research. Water Re-
sources Thesaurus. (Nov. 1966)
7 Geckler, JackR., Mackenthun, K. M.,
and Ingram, W. M. Glossary of
Commonly Used Biological and
Related Terms in Water and Water
Control. Env. Health Series, U. S.
Dept. HEW (July 1963)
8 Mathews, John E. Glossary of Eco-
logical Terms. Roberts. Kerr
Water Research Center, Ada, OK
In press.
¦^•ZOOGLOEA - A jelly-like matrix developed
by certain microorganisms at some
stage in their life cycle. Commonly
associated with sludge flocculation in
biochemical treatment operations.
ACKNOWLEDGMENTS:
This outline was prepared by F. J. Ludzack,
Many individuals, unpublished memoranda Chemist, National Training Center, FWPCA,
and literature sources contributed to the SEC, Cincinnati, OH 45226
selection of terms and key ideas included
in this glossary. Contributors are too
numerous to list individually, but their
assistance is gratefully acknowledged.
47-19
-------
Aid to Multiplication and Division
48-1
PC. WAS. con 1. 10 68
-------
Pollutional
Load
Pounds
Per
Day
Concentration of Pollutional Load
for Various Flows
eO 70 sO s010 O
Flow - cfs
Source: Thomas J. Powers, III. FWPCA, Department of the Interior
48-2
-------
£
CO
o
c
o
XT
o
8
to
0)
-------
Thousands of
Cubic Feet
Lagoon Holding Capacities
i,3oq
z
1,200
I.UjQ
1
II
m:\h
1 2
Source: Thomas J. Powers,
4- >
Lagoon Area, acres
III. FWPCA, Department of the Interior
-------
POWERS DATA SHEET No. 397
2.5-
"\ *V Hill ion Ftoanda I*r
ooaX V ^
, X0.6 Million Gallons Hr
-•.5
- iar* Feet Rir btr
^Aere Feet R»r JO
¦n»
Acre FNt FfcrDfcy --
Gellonaffer Mirrate —-
^Cubic Feet F^r Second'
Flow of Fluids Conversion Chart
With this chart you can conveniently deter-
mine equivalent units of discharge for fluids.
Merely line up a straight edge with the middle
of the chart and a known discharge; read the
equivalent on the other scales.
Example: Discharge from a given pipe is
1100 gallons per minute. How many gallons
per day are discharged? Lining up 1100 on
the gallons per minute scale with the chart
center, we read 1, 580, 000 gallons per day on
the appropriate scale. On other scales we
can determine that the flow is equivalent to
2.45 cu ft per sec.
The scales cover sufficient range to allow you
to find values of any magnitude by multiplying
or dividing the scales by factors of ten. With
a little ingenuity, you can determine several
units not shown directly.
"Reprinted with permission from POWER, October 1965"
"Copyright McGraw-Hill, Inc., 1965."
S. R. Ross, Denver, Colorado
48-5
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