United States
Environmental Protection
Agency
Environmental Research
Laboratory
Corvallis OR 97330
EPA-600/3-79-003
January 1979
Research and Development
SEPA
Performance of
Aerated Lagoons in
Northern Climates
-------
REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are.
1 Environmental Health Effects Research
2. Environmental Protection Technology
3 Ecological Research
4 Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7 Inleragency Energy-Environment Research and Development
8 "Special" Reports
9 Miscellaneous Reports
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
[ion Sen/ire, Springfield, Virginia 22161.
-------
EPA-600/3-79-003
January 1979
Performance of Aerated
Lagoons In Northern Climates
C. D. Christiansen
H. J. Coutts
Arctic Environmental Research Station
U. S. Environmental Protection Agency
College, Alaska 99701
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OREGON 97330
-------
DISCLAIMER
This report has been reviewed by the Corvallis Environmental
Research Laboratory, U. 5. Environmental Protection Agency,
and approved for publication. Mention of trade names or
commercial products does not constitute endorsement or
recommendation for use.
-------
FOREWORD
Effective regulatory and enforcement actions by the Environ-
mental Protection Agency would be virtually impossible
without sound scientific data on pollutants and their impact
on environmental stability and human health- Responsibility
for building this data base has been assigned to EPA's Of-
fice of Research and Development and its 15 major field in-
stallations, one of which is the Corvallis Environmental
Research Laboratory (CERL).
The primary mission of the Corvallis Laboratory is research
on the effects of environmental pollutants on terrestrial,
freshwater, and marine ecosystems; the behavior, effects and
control of pollutants in lake systems; and the development
of predictive models on the movement of pollutants in the
biosphere. CERL's Arctic Environmental Research Station
conducts research on the effects of pollutants on Arctic and
sub-Arctic freshwater, marine water and terrestrial system;
and develops and demonstrates pollution control technology
for cold-climate regions.
This report examines the performance of cold climate aerated
lagoons and presents the results of lagoon studies conducted
by the Arctic Environmental Research Station.
Jame s McCarty
Acting Director, CERL
m
-------
ABSTRACT
Studies of cold climate aerated lagoons conducted by the
Arctic Environmental Research Station, Fairbanks, Alaska are
reported. Conclusions are based on these studies, observa-
tions of full scale aerated lagoons operating in Alaska and
reports on lagoons in the northern tier of the United States
and Canada.
Biological processes which occur in facultative aerated
lagoons are reviewed and the performance of cold climate
aerated lagoons is examined. Winter and summer performance
is compared, and general criteria for the design of cold
climate lagoons is presented. Sample calculations for
predicting the performance of aerated lagoons are also
shown. These calculations are based on the complete mix
equation for aerated lagoon design and on the results of the
data analysis presented in this report. The information
presented indicates that lagoons can be designed or upgraded
to meet P. L. 92-500 secondary standards. This may be done
by increasing the number of cells in series, by reducing
short circuiting and through the use of a polishing pond.
It is shown that additional cells in series, for a given
detention time, will increase the BOD removal efficiency of
a 1agoon .
IV
-------
CONTENTS
Foreword -j-ji
Abstract iv
Figures vii
Tables x
Acknowledgment xii
1. Introduction 1
2. Conclusions and Recommendations 2
3. Background 5
Lagoon Studies in Alaska 5
Facultative Aerated Lagoons 6
BOD Removal 8
Temperature Effects 8
Mixing and Short-Circuiting 9
Sludge Accumulation 11
Algae 12
Coliforms 14
Aeration 16
Oxygen Transfer 18
Lagoon Design 24
4. Methods of Analysis and
Lagoon Description i Performance Characteristics . 26
General Information 26
Sampling and Analysis 27
1) Eielson Air Force Base Experimental
Lagoon 28
2) Ft. Greely Lagoon 28
3) Northway Lagoon 30
Eielson Air Force Base Experimental Aerated
Lagoon 30
1) Lagoon Description 30
2) Operation Problems 33
3) BOD and SS Removals 34
4) Algae Growth 45
5) Coliforms 47
6) Nutrients 49
Ft. Greely Lagoon 49
1) Lagoon Description 49
2) Aerator Performance 51
3) BOD and SS Removals 58
4) Sludge Accumulation 65
5) Algae Growth 68
6) Nutrients 68
-------
Northway Lagoon 70
1) Lagoon Description 70
2.) BOD and SS Removals 71
3) Bottom Sludge 74
4) Nutrients 77
Eagle River Lagoon 78
1) Lagoon Description 78
2) Operation Problems 79
3) BOD and SS Removals 82
4) Coliforms 86
Eielson Air Force Base Full Scale Lagoon. • • 89
1) Lagoon Description. • 89
2) Operation Problems 89
3) BOD and SS Removals 90
4) Coliforms 93
Palmer Aerated Lagoon and Polishing Pond ... 93
1) Lagoon Description 93
2) Operation Problems 95
3) BOD and SS Removals 96
Studies by Others 99
5. Short-Circuiting 108
6. Ft. Greely Oxygen Transfer Studies 114
Methods and Procedures 114
Results 117
Oxygen Budget 122
7. Discussion 125
BOD and SS Removal . 125
Soluble BOD Removal 131
Reaction Rates 133
Sludge Accumulation. 140
Algae 144
Nutrients 145
Coliforms 146
Aeration Systems 149
Aeration Diffusers 151
8. Lagoon Design and Upgrading 155
Discussion 155
Sample Calculations 160
References 171
VI
-------
LIST OF FIGURES
Number Page
1 Eielson Air Force Base Experimental Lagoon
2 EAFB Experimental Lagoon Performance with Fine Bubble
and Coarse Bubble Diffuser Systems 42
3 EAFB Experimental Lagoon Performance with 6 Cell and 4
Cell Operation 43
4 EAFB Experimental Lagoon Winter and Summer Percent BOD
Removal and SS Remaining vs. Detention Time 44
5 EAFB Experimental Lagoon Chlorophyll and Suspended
Solids vs. Detention Time 46
6 Plan View of Ft. Greely Coarse Bubble Aerator Instal-
lation 52
7 Chicago Pump Shearfuser Cluster 53
8 Aer-0-Flo Non-clog Diffuser Cluster 54
9 Ft. Greely Fine Bubble Diffuser Performance Data .... 55
10 Ft. Greely Coarse Bubble Diffuser Performance Data ... 57
11 Fine Bubble Diffuser Summer Aeration Pattern 59
12 Fine Bubble Diffuser Winter Aeration Pattern 60
13 Coarse Bubble Diffuser Summer Aeration Pattern 61
14 Coarse Bubble Diffuser Winter Aeration Pattern 62
15 Ft. Greely Aerated Lagoon Sludge and Liquid Tempera-
ture, 1971 - 1972 • 67
16 Ft. Greely Aerated Lagoon BOD, Chlorophyll and
Suspended Solids vs. Summer Sampling Dates, 1972- ... 69
17 Eagle River Aerated Lagoon Sludge Blanket 81
vn
-------
18 Eagle River Aerated Lagoon Operating Results 85
19 Eagle River Aerated Lagoon Effluent BOD and Suspended
Solids Variability 87
20 EAFB Full Scale Lagoon Operating Results 91
21 Palmer Lagoon Operating Results 98
22 Palmer Lagoon Effluent BOD and Suspended Solids
Variability 100
23 Visual Observation of Dye Injection in the Ft. Greely
Lagoon... 110
24 Dye Injection Results, Ft. Greely Coarse Bubble
Aerated Lagoon. . Ill
25 Dye Injection Results, Ft. Greely Fine Bubble Aerated
Lagoon 112
26 Air Flow Rate vs. K. a .V for Aerated Lagoons 120
27 Year-round Percent BOD Removals vs. Detention Time • • 126
28 Year-round Percent Suspended Solids Remaining vs.
Detention Time 128
29 Winter Percent BOD Removal a'nd Percent Suspended
Solids Remaining vs. Detention Time 129
30 Summer Percent BOD Removals and Percent Suspended
Solids Remaining ..... . 130
31 Soluble BOD vs. Detention Time . 132
32 Overall BOD Removal Rate Coefficient vs. Loading. . . 134
33 Overall Suspended Solids Removal Rate Coefficient vs.
Loading 135
34 Winter BOD Removal Rate Coefficient vs. Loading. . . . 136
35 Summer BOD Removal Rate Coefficient vs. Loading. . . . 137
36 Winter Suspended Solids Removal Rate Coefficient vs.
Loading.............. 138
37 Summer Suspended Solids Removal Rate Coefficient vs.
Loading....... 139
vm
-------
38 Aerated Lagoon Coliform Removals 147
39 Eagle River and EAFB Full Scale Lagoons Fecal Coliform
vs. Chlorination Contact Time 148
40 Suggested Lagoon Arrangement . 158
41 Effect of Cells in Series on Detention Time 169
-------
TABLES
Number Page
1 Performance Summary of EAFB Experimental Lagoon- ... 35
2 EAFB Experimental Lagoon Total Coliform Removal
Results 48
3 EAFB Experimental Lagoon Nutrient Removal Summary . . 50
4 Performance Summary of Ft. Greely Aerated Lagoon. . . 63
5 Ft. Greely Aerated Lagoon Sludge Analysis 66
6 Ft. Greely Aerated Lagoon Nutrient Removal Summary. . 70
7 Performance Summary of Northway Aerated Lagoon .... 72
8 Northway Aerated Lagoon Sludge Analysis 75
9 Northway Aerated Lagoon Nutrient Removal Summary. . . 78
10 Eagle River Aerated Lagoon Performance Summary .... 83
11 Eagle River Aerated Lagoon Disinfection Summary. ... 88
12 Performance Summary of Eielson Air Force Base Full
Scale Lagoon 92
13 EAFB Full Scale Lagoon Disinfection Summary 94
14 Palmer Lagoon Performance Summary 97
15 Performance Summary of Minnesota Lagoons 102
16 Performance Summary of Winnepeg Lagoons 105
17 Performance Summary of Harvey, North Dakota Aerated
Lagoon..... 106
-------
18 Harvey, North Dakota Aerated Lagoon Fecal and Total
Coliform Results 107
19 Oxygen Transfer Summary 118
20 Ft. Greely Coarse Bubble Lagoon Oxygen Budget 124
21 Sludge Accumulation Summary 143
XI
-------
ACKNOWLEDGMENT
This report is a summary of work on aerated lagoons which
was initiated by Mr. Sidney E. Clark, first Waste Treatment
Research Director, Arctic Environmental Research Sta-
tion (AERS). His contribution is gratefully acknowledged.
Much of the work covered in this report was accomplished
with the cooperation of the U. S. Air Eorce and U. S. Army.
Through an interagency agreement with the Alaskan Air Com-
mand, the AERS constructed and operated, with Air Force as-
sistance, an experimental facility at Eielson Air Force
Base, Alaska. Much of the information contained in this
report was obtained from an aerated lagoon constructed as
part of the experimental facility. Another interagency
agreement with the U. S. Army, Alaska, allowed the AERS to
modify a full scale aerated lagoon at Ft. Greely, Alaska
which also resulted in a significant amount of the informa-
tion included in this report. Additional information was
obtained from a lagoon at Northway, Alaska through the
cooperation of the Federal Aviation Administration.
The following individuals are acknowledged as providing data
or information which contributed significantly to the
completion of this report: Claude Vining and Ed Pohl of the
Corps of Engineers, Anchorage; Jack Howard, Jim O'Niel and
the Waste Plant Operators, Eielson AFB; Mr. Mullens and Del
Ivester, Ft. Greely; Dick Hutson and Mike Pollen, Anchorage
Area Borough; William Curtis and Jim Giyer, Palmer, Alaska.
XI1
-------
INTRODUCTION
Waste treatment lagoons have become increasingly popular in the
United States and Canada. In spite of this fact, sufficient in-
formation has not been available to establish sound design
criteria, particularly for cold climate regions. As was stated
in a recent state-of-the-art review (McKinney, et al. 1971),
"Only in a few instances has there been development of basic data
sufficient to produce sound criteria. While there has been a
large number of studies in waste treatment lagoons, most of these
studies have been fragmented and lacking in sufficient depth to
have raal meaning. If we are to continue to design and construct
waste treatment lagoons, it is important that we have proper
design criteria that will result in the production of the desired
effluent quality".
Aerated lagoons have many advantages which make them very
desirable for use in Alaska, especially since t-he standards for
lagoons have been revised. The new standards allow for higher
effluent suspended solids during summer months to accommodate al-
gae growth. Among the advantages of lagoons are low operating
and maintenance requirements, resistance to upsets and built-in
sludge digestion and storage capabilities. A major disadvantage
is the large land area requirement.
1
-------
CONCLUSIONS & RECOMMENDATIONS
The performance of lagoons in northern climates has been
evaluated. Methods for predicting the performance of aerated
lagoons in northern climates have been derived from pilot plant
and full scale operating data. Conclusions can be drawn as fol
lows :
1. Lagoon systems which can meet secondary standards can be
designed for northern climates. Raising the allowable sum-
mertime effluent suspended solids should make the aerated
lagoon a more attractive alternative.
2. The following considerations should be kept in mind in
designing or upgrading lagoon systems (see the section on
lagoon design and upgrading):
a. Special attention should be given to the possibility of
short-circuiting within the cells. Strategic placement
of baffles and aerators can reduce this problem.
b. Lagoon cells should be provided in series to red»ce
short-circuiting due to complete mix conditions. Cells
in series also result in greater reductions in bacteria
and algae for a given detention time.
-------
c. Heavy aeration should be provided at the lagoon influent
in order to maintain influent solids in suspension. This
will increase the rate of conversion of dissolved and
colloidal solids to suspended solids, which can be
removed by sedimentation. Also, the solids will undergo
some aerobic decomposition and help prevent buildup of
sludge under septic conditions which can retard
digestion.
d. Adequate sludge storage (1500 liters/1000 m of domestic
sewage) should be provided in the first sections of the
lagoon so that aerobic oxidation of summer sludge diges-
tion byproducts will occur in succeeding cells before the
effluent is discharged.
e. A polishing or maturation pond should be provided as the
last cell in series.
f . The limited data on disinfection indicates that summer
algae production results in disinfection rates similar to
those during cold temperature operations in winter-
The performance of coarse bubble diffusers in aerated lagoons has
been evaluated. The coarse bubble diffuser can provide an at-
tractive alternative to the fine bubble diffuser for aeration in
lagoons. Conclusions may be reached as follows:
1. Fine bubble diffusers are more efficient in oxygen transfer
than coarse bubble diffusers, however, they are not neces-
sarily more economical.
-------
2. Power requirements in terms of Ib. 0_ transferred/hp-hr may
be higher for fine bubble diffusers because of the restricted
openings which require higher blower discharge pressures.
3. Maintenance requirements for fine bubble diffusers are higher
because of clogging which requires periodic cleaning. The
clogging also results in higher compressor maintenance due to
increased discharged pressures.
4. Oxygenation efficiencies published in the literature or sup-
plied by coarse bubble diffuser manufacturers may be used for
aerated lagoon design.
5. In areas where ice fog is a problem, a larger number of dif-
fusers (less air flow per diffuser) at an increased spacing
would minimize the generation of ice fog without sig-
nificantly affecting oxygenation efficiencies.
6. Excluding transfer efficiency, a ratio of 1.5 g 0?/g BOD,.
removed was found adequate for sizing aeration equipment for
cold climate aerated lagoons.
-------
BACKGROUND
LAGOON STUDIES IN ALASKA
Pohl (1967) presented a theoretical discussion of cold climate
aerated lagoons. Clark et al., (1970) provided an extensive sum-
mary of lagoon operations under cold climate conditions and
Grainge et al . , (1972) reviewed Canadian experiences with
lagoons. Design criteria for arctic and subarctic aerated
lagoons has been presented by Reid (1970, 1975).
One of the first aerated lagoons in Alaska was an experimental
facility located at the Eielson Air Force Base near Fairbanks and
operated by the Arctic Health Research Center of the U.S. Public
Health Services in 1964 and 1965 (Reid, 1970). This lagoon
established the feasibility of utilizing aerated lagoons in the
subarctic. Late in 1967, the Alaskan Air Command and the Arctic
Environmental Research Station entered into an agreement to con-
struct and operate a field research facility that included an
aerated lagoon pilot plant at Eielson Air Force Base. Also,
during this period, Pohl (1967) presented an approach for the
design of aerated lagoons. Based on the information established
from these initial efforts and the Alaska State Water Quality
-------
Standards in effect at that time, a number of aerated lagoons
were constructed in Alaska, particularly for remote government
installations. These lagoons have been successful for the most
part but have not been without problems and were generally unable
to meet the 30/30 secondary standards required by Public Law
92-500.
The secondary standards for lagoons have been revised to allow
for higher effluent suspended solids (SS) levels during summer
months (Federal Register, 1977). The Alaska Operations Office
of the Environmental Protection Agency has submitted a value of
70 mg/1 as the SS limit for summer operation (Dan Crevenston,
Personal Communication 1977). The effluent must also appear
green for this high value to apply. The standards for BOD ef-
fluent levels remain the same. The 70 mg/1 value is base on ac-
tual lagoon operating data and applies to the state of Alaska
only, since each state is required to determine a value in-
dividually. This approach will allow lagoons to be designed
based on BOD requirements but eliminates the need for special
equipment or operations for algae removal.
FACULTATIVE AERATED LAGOONS
The incomplete mix or facultative aerated lagoon is designed with
sufficient aeration capacity to ensure uniform oxygen concentra-
tion throughout the liquid but insufficient capacity to maintain
-------
solids in suspension. As raw waste enters the lagoon, the
settleable solids are deposited while the soluble and colloidal
organic matter undergo assimilation and oxidation. As the
suspended solids (SS) undergo oxidation, a portion of these are
deposited also .
The settled sludge undergoes anaerobic decompostion . The degree
of decomposition is directly related to temperature. The
byproducts of anaerobic decomposition are diffused into the
aerobic liquid to undergo further oxidation. In the presence of
sunlight, algal growth also occurs, converting carbon dioxide in-
to organic compounds and oxygen.
Four principal biological transformations which occur in all
types of lagoons are described by Oswald (1968). These are:
(1) aerobic oxidation which produces bacterial sludge, carbon
dioxide and water; (2) anaerobic decomposition which produces or-
ganic acids and related compounds; (3) organic acid decomposition
which forms methane and carbon dioxide; (4) algal growth which
converts carbon dioxide into organic compounds .and free oxygen.
Knowledge of these reactions is essential for an understanding
of the facultative aerated lagoon.
-------
BOD REMOVAL
Eckenfelder (1970) has presented the relationship which is used
for lagoons approaching a completely mixed regime. Based on a
material balance, the following first order reaction equation can
be developed:
Se/So = l/(l+Kt)
where K = k X
S = Influent BOD
o
5 = Soluble effluent BOD
e
X = Basin volatile suspended solids
t = Detention time, days
K & k = Removal rate coefficient.
Because of the present inability to define the rate of solids
settling, etc., in an incomplete mix lagoon, the overall reaction
rate coefficient K is generally used.
TEMPERATURE EFFECTS
The effect of temperature on biological process reaction rates
can be predicted by the following relationship:
-------
K206
(T-20.)
K
T
K
20
T
= Desired reaction rate at temperature T
= Known reaction rate 20°C
= Temperature
= Temperature coefficient
Values of 0 vary widely depending on the type of process con-
sidered .
Eckenfelder and England (1970) summarized temperature effects as
follows:
Process
Stabilization Pond
Activated Sludge
Aerated Lagoon
Tr ickling Filter
Aerobic Facultative Lagoon
Anaerobic Lagoon
Extended Aeration
MIXING AND SHORT-CIRCUITING
Flow through lagoons have been described as either plug or com-
plete mix as characterized by the following equations:
Range of 6^
1.072 - 1.085
1.0 - 1.041
1.026 - 1.058
1.035
1.06 - 1.18
1.08 - 1.10
1.037
Temperature
Range °rj
3-35
4-45
2-30
10-35
4-30
5-30
10-30
-------
Plug Flow S /S = e~kt
3 e o
Complete Mix S /S = l/(l+Kt)
G O
Thirumurthi (1969), indicated that neither condition exists in
sanitary engineering practice and that actual conditions are
somewhere in between. He presented an equation for organic
removal which included a dispersion coefficient which would ac-
count for short-circuiting and mixing characteristics, exit and
entrance conditions, etc. Murphy and Wilson (1974) have also
reported that lagoon mixing patterns differ significantly from
either complete mixing or plug flow conditions and used a disper
sion coefficient in describing organic removals. These methods
require extensive knowledge of lagoon characteristics. Murphy
and Wilson suggested that the following equation be used for
rapid analysis of aeration basins in series.
n
S /S = n(l/(l+Kt.))
G Q 1
t. = Residence time for each
respective cell.
The provision of a number of aeration cells in series will im-
prove lagoon performance by reducing the opportunity for short-
circuiting and by providing conditions more closely related to
plug flow. Gloyna and Aguirre (1970) reported greater suspended
10
-------
solids and bacterial reductions in facultative ponds operated in
series compared to single cell units. Reid (1975) has suggested
that providing more than four cells in series will not improve
performance significantly.
Some mixing is required to provide adequate dissolved oxygen
levels throughout the lagoon. In general, this is accomplished
when sufficient aeration is supplied for biological oxidation.
Mixing also prevents thermal stratification and allows the bottom
sludge to warm up during the summer months which should increase
anaerobic activity.
SLUDGE ACCUMULATION
Because of the low mixing levels which occur in long detention
time lagoons, deposition of biological sludge occurs. Clark
et al . (1970), summarized cold climate facultative pond installa-
tions and reported accumulations of 250-400 liters per
1000 people per day (8.8 - 14.0 cu. ft./1000 people-day).
Middlebrooks et al. (1965), in an investigation of sludge ac-
cumulation in lagoons, determined that where the percentage of
total solids is high the volatile portion is generally low. This
condition would indicate that a large portion of the sludge must
be silt and other inorganic matter washed into the lagoon. The
time required for thorough digestion in sludge lagoons is
estimated at 3 years (Vesilind, 1975). For streams in temperate
11
-------
climates, Fair has estimated the rate at which sludge deposits
stabilize as follows (Mueller and Su, 1972):
50% 0.3 years
90% 1.5 years
99% 5.4years
These values indicate that it takes at least 5 years for an
aerated lagoon to reach equilibrium and to complete the aging
process.
ALGAE
Algae exist in lagoons in a symbiotic relationship with bacteria
and require H?0, inorganic nutrients and carbon dioxide for
growth. Typical green algae found in lagoons are Chlorella,
Chlamydomonas and Euglena with the latter two tending to dominate
in cooler weather (Gloyna, 1968).
Studies have shown that massive algal blooms are associated with
excessive amounts of decomposable organic matter and that C0? is
the major nutrient required for growth (Kuentzal, 1969), (Foree
and Wade, 1972). Kuentzal (1969) reported that bacterial action
on large amounts of organic matter can supply as much as 20 mg/1
of C0_ in a super saturated state and result in large algal bloom
development.
12
-------
Waste stabilization ponds which receive optimum amounts of waste
for growth conditions discharge planktonic algae whereas, in
ponds receiving relatively small loads, the algae settle out
and/or are consumed by planktonic phagotrophs such as Daphnia or
Cyclops (Gloyna, 1968). Dinges (1975) has described the environ-
ment desirable for cultivating zooplankton, which he indicated
can filter and consume bacteria, colloids and algae in stabiliza-
tion ponds. He suggested the following:
(1) pH should be maintained between 7.0 and 8.0.
Ammonia dissociates at high pH levels and
becomes toxic to a variety of zooplankton.
High pH results from excessive algae growth.
Algae can be controlled by reducing organic
carbon which is converted to carbon dioxide
by bacterial respiration.
(2) Dissolved oxygen should be 1 mg/1 or greater
as the zooplankton will not survive under
anaerobic conditions.
(3) Gentle mixing should be present to prevent
pockets of stagnation and preclude soluble
sulphide evolution. Wind action can
generally provide sufficient mixing.
(4) Rubble will increase the productive poten-
tial by providing living space.
13
-------
COLIFORMS
A reduction in coliforms of several orders of magnitude occurs
in aerated lagoon and oxidation pond treatment systems. Disin-
fection may be necessary, however, in order to meet state water
quality standards. The disinfection step in aerated lagoon
design apparently receives little attention other than to provide
a contact chamber of a certain nominal retention time and a means
of feeding chlorine to the effluent stream.
Two aspects of disinfection of aerated lagoons in the sub-arctic
must be considered: the algae blooms which occur during the warm
summer months of long daylight hours, and the long period of near
0°C effluent temperatures during winter months, which increases
pathogen survival rates and affects disinfection requirements.
Both situations require special attention in the design of lagoon
treatment systems.
Slanetz et al . (1970) found die off rates of 95-99?o in wastewater
oxidation systems utilizing one pond or two ponds in series at
17-26°C. The ponds were 5 to 10 acres in size. Much better sur-
vival rates were found in the winter at pond temperatures of
1-10°C. Salmonellae and viruses were isolated in the majority
of effluent samples. Systems having 3 or 4 ponds in series
resulted in very few indicator bacteria remaining in the ef-
fluent. The numbers of bacteria were again much higher in the
winter and enteric pathogen isolations more frequent. Gordon
14
-------
(1972) has shown the survival rates of indicator bacteria are
much greater in subarctic streams under winter conditions.
Mixing is very important for efficient chlorine disinfection.
White (1972) has shown that high suspended solids levels have
little effect on chlorine requirements when adequate premixing
is provided.
The chlorination of treated wastewater effluents at 0-10°C have
been investigated in a model contact chamber at the AERS (Gordon
et al . 1973). The results of the study indicated that effective
chlorination can be accomplished at temperatures less than 1°C
provided an actual contact time of no less than one hour is
provided and adequate premixing of the chlorine is practiced.
These conditions seldom occur in practice. The authors reported
a nominal detention time of 2 hours was necessary in the well
baffled contact chamber model to provide a one-hour actual con-
tact time .
A number of studies indicate that successful chlorination of al-
gae laden oxidation pond effluents can be attained; however, the
BOD of treated wastewater effluent containing algae can be in-
creased by excessive chlorination (White, 1972). Horn (1970) sug-
gested that two reactions appear to occur: first, the algae
suffer surface damage and, second, the cellular contents are
released which increases the BOD. Bacteria can be destroyed and
the algae left essentially intact by controlling time of reaction
15
-------
and concentration of chlorine. The following optimal conditions
were reported :
Chlorine (mg/1)
Contact Time (Min) Applied Residual
15 5.0 2.4
60 3.4 1.0
Kott reported work on 5 simulated pond effluents using raw and
secondary treated domestic sewage in which no algae kill occurred
with up to 2 hours detention time and 8-14 mg/1 chlorine dosages
(White, 1972). Indicator bacteria were reduced from 10 and
107/100 ml down to less than 20/100ml after 30 min. at 30°C.
White (1972) recommended the chlorination chamber for wastewater
ponds be designed for one hour contact time at average flow but
not longer than two hours. The velocity should be 2 ft/min. to
prevent deposition of dead algae and adequate provisions for
cleaning should be made. The chlorination equipment should
provide for 15 mg/1 dosage at maximum flow.
AERATION
Oxygen requirements based on biological sludge synthesis and
respiration and the bottom sludge demand have been discussed by
Pohl (1970). The relationship for the synthesis of new cellular
material is expressed as follows (Eckenfelder and O'Connor,
1961) :
16
-------
S = al_ - bS
r a
where S = net accumulation of Volatile
suspended solids
a = fraction of 5 day BOD removed which is
synthesized to new biological sludge
L = Ib/day BOD removed
b = rate of endogenous respiration,
fraction per day
S = Ib of mixed liquor volatile
3
suspended solids.
The oxygen required per day for synthesis and respiration is
determined by the following equation (EckenfeIder, 1970)
Ib 00/day = a' S + b1 MLVSS
2 r
a' = 1-a based on ultimate BOD
b' = 1.4b
For the 5 day BOD, the following conversion must be used
a1 = BODu/BOD5 - 1.42a
In aerated lagoons in which solids deposition is allowed to occur
and BOD is fed back to the liquid from anaerobic fermentation,
the following relationship can be used:
Ib of 0 /day = a11 Ib BOD removed/day
17
-------
Values of a11 should be 1.2 to 1.4. In other words, the oxygen
requirement for oxidation of digestion products is increased by
20 to 40?o. Endogenous respiration is ignored because of the low
suspended solids level in the basin.
The aeration system requirements for aerated lagoons have been
reviewed elsewhere (Christiansen and Smith, 1973). Surface
aerators are not recommended for cold climate operations because
of icing problems which occur (Penman, 1970), (Clark et al.,
1970) .
OXYGEN TRANSFER
The general transfer equation for oxygen in wastewater is as fol
lows :
dc/dt = 0K, a(BC -C) - r
L S
dc/dt = Change in concentration (mg/l-hr)
K. a = Overall transfer coefficient (hr~ )
a = Ratio of K. a in a wastewater to K. a
of tapwater
Cg = Oxygen saturation concentration (mg/1)
C = Oxygen concentration in liquid (mg/1)
3 = Ratio of C in wastewater to C
s s
in tapwater
r = Oxygen Demand Rate (mg/l-hr)
18
-------
The overall oxygen transfer coefficient K. a, can be used for
determining the performance of aerators. Examination of the
above equation shows that when a biological system is operating
under steady state conditions, the rate of oxygen transfer will
equal the oxygen demand rate. Therefore, by determination of the
oxygen demand rate, a , g , and oxygen in the liquid, K. a can be
calculated (Benjes, 1969), (Conway and Tumke , 1966), (Ecken-
felder, 1959).
Several attempts have been made to predict the value of K. a in
diffused air systems. Eckenfelder, 1959 has shown that for a
given aerator, K. a is influenced by air flow rate, depth of dif-
fuser submergence and the tank and aerator configuration. Smith
(l970) has shown that diffused air systems can be scaled up
geometrically. The following equation was developed by Ecken-
felder :
C Gs(1-n)H2/3
K - 3 —
v
C = Constant
G = Air flow rate per diffuser
o
H = Liquid depth
V = Basin volume per diffuser
(1-n) = Gas rate exponent characteristic of
diffuser type
19
-------
The exponent of 2/3 for H has been found to vary for commercial
aeration tanks with the values of 0.88 for sparjers and 0.72 for
saran tubes reported (Eckenfelder and Ford, 1968).
Eckenfelder 1961 has indicated surface transfer in lagoons will
be 10 - 20 percent of the total. Since the transfer rate is in-
dependent of diffuser spacing provided the spacing is sufficient
to minimize interfering bubble patterns (Eckenfelder, 1968), dif-
fuser placement is not expected to be a factor in larger aeration
basins .
The difference between the oxygen saturation concentration and
the concentration in the liquid is the driving force for the
transfer process. The average saturation value (C ) at tank mid-
s
depth is used and may be determined as follows (Eckenfelder and
O'Connor, 1961).
Cs = Cw(Pb/29 + Ot/42)
where C = Oxygen saturation concentration at
barometric pressure
P. = Psia at aerator depth
0, = Percent oxygen by volume in air
leaving tank
Regarding the effects of wastewater on C , the effect is rela-
S
tively minor when the dissolved solids in an aeration basin are
less than 0.2 percent. Values of 0.95 have been found for B
where dissolved solids were in this range (Pfeffer, 1969).
20
-------
The effect of wastewater on K.a is considerable more difficult
to evaluate and extreme care must be used in its application.
Eckenfelder and O'Conner (1961) and Eckenfelder and Ford (1968)
list a values for various wastes and aerators. They indicate,
however, that evaluation of a requires measurement of the respec-
tive K.a values under mixing intensities and surfactant levels
found in practice.
The K, a value is also influenced by temperature which may be ac-
counted for through the Arrhenius temperature correction equation
related to 20°C as follows:
KLa(T) = KLa(20)e(T~20)
0 = Temperature Coefficient
T = Temperature, °C
Pfeffer (1969) stated that reported values of 0 range from 1.016
to 1.047 and that 1.024 is frequently used. He suggested that
in most practical systems the value will be between 1.02 and
1.03- Eckenfelder and Ford (1968) indicated an evaluation showed
0 to be 1.02 for K. a in a bubble aeration system. Hunter and
Ward (1972) found that K.a varies linearly with' temperature.
However, their data show a relatively small difference between
the use of 1.024 for 0 in the Arrhenius equation and the linear
model between 0°C and 25°C.
21
-------
The following > 3 a brief description of some submerged aeration
device, '-j which have been utilized in aerated lagoons:
1, Perforated tubing diffusers (Air Aqua Systems) supplied
by Hinde Engineering Company, Highland Park, Illinois, consists
of flexible plastic tubing with perforations cut on the top and
a lead keel on the bottom to keep it submerged. This type of
aeration was originally used for the upgrading of stabilization
lagoons.
2. Porous ceramic diffusers supplied by Hydro Ceramic Com-
pany, Anchorage, Alaska (Pohl, 1970). Consists of PVC tubing
with porous ceramic stones inserted one foot apart. Each stone
provides about 3.2 sq cm of surface area. The tubing is sup-
ported off the lagoon bottom by pylons.
3. Air Gun aerators supplied by Aero-Hydraulics Corp., Mon-
treal (Dutton and Fisher, 1966), (Penman, et al., 1970). These
consist of submerged vertical plastic pipe normally 30 cm in
diameter and of varying lengths with an air chamber at the lower
end. Air is pumped into the chamber and builds up until released
by a siphoning effect through the pipe. The rising air bubble
"piston" draws in water from holes in the pipe located j»ust above
the air chamber and a pumping action occurs. Air Gun aerators
are designed for use in deeper lagoons and promote mixing as well
as oxygenation.
22
-------
4. The INKA aeration system designed by Industrikemeska Ak-
tiebologet of Stockholm, Sweden, was studied in a pilot lagoon
at Laramie, Wyoming (Champlin, 1971). The INKA aeration system
is designed for low pressure operation and in this case consisted
of three grids of 1 m X 2.5 m with 5 mm orifices located on the
bottom of the grid. The grids were placed at a depth of 0.8 m
below the surface and circulation in the lagoon was controlled
by baffling.
5. Aer-0-Flo non-clog diffussrs supplied by Aer-0-Flo Cor-
poration, Florence, Kentucky. Consists of a cap which rests on
a 3 mm pipe orifice. When air is flowing, differential pressure
raises the cap about 1.6 mm. Air flows radially under the cap,
theoretically rising through small holes in the cap. When air
is shut off, the cap falls back against the orifice and prevents
solids from backing up in the system, simulating a check valve.
6. Chicago Pump Shearfusers supplied by Chicago Pump Co.,
FMC Corp., Chicago, Illinois. Consists of a bo* 19 cm square
with a one-inch air injection orifice entering the side near the
bottom. As air rises in the box, water is pulled in and the
resulting shearing action causes the air to break up into smaller
bubble s.
7. Kenics Aerator supplied by Kenics Corporation, Danvers,
Massachusetts. The aerator is a motionless mixer consisting of
a polyethylene tube and alternating right and left hand helices.
The units act as air lift devices.
23
-------
LAGOON DESIGN
That lagoons c aTi be designed and operated to meet the standards
has been demonstrated. Oswald et al. (1970) described a lagoon
system at Saint Helena, California, which achieved excellent ef-
fluent characteristics including an average BOD level of
3.9 mg/1. The lagoon system consisted of facultative, aeration,
algae sedimentation and two maturation ponds, all in series and
totaling 110 days detention time. Other methods of meeting stan-
dards without the need for polishing filters, etc., have also
been described. Pierce (1974) reported on 49 lagoons in Michigan
practicing long term storage prior to effluent release. He in-
dicated that lagoons can produce effluents meeting EPA require-
ments for BOD and fecal coliforms and generally can meet the
suspended solids requirements by practicing long term storage and
discharging in the spring and fall. Hiatt (1975) reported on a
pilot program of phase isolation in which lagoon effluents were
transferred to a pond and held for 2 weeks before discharge. Ex-
cellent results were obtained with extreme reductions in the al-
gae populations, apparently due to the change in conditions ex-
perienced by the algae after transfer to the holding pond.
Oswald et al. (1970) has suggested that optimum removals cannot
be obtained from any one type of lagoon because of the many dif-
ferent biological processes which occur. Optimum conditions for
one process will not necessarily be optimum for another. He has
24
-------
suggested that different types of lagoons operating in series are
necessary for an optimum lagoon system.
25
-------
METHODS OF ANALYSIS AND
LAGOON DESCRIPTION & PERFORMANCE CHARACTERISTICS
GENERAL INFORMATION
Following is a brief summary of some subarctic aerated lagoon
performance information which supports the conclusions presented
in this report. Information included in this section has been
obtained from experimental and full scale aerated lagoons located
at Eielson Air Force Base (EAFB), Northway, Ft. Greely, Eagle
River and Palmer. The EAFB experimental lagoon was part of an
experimental facility constructed jointly by the Alaskan Air Com-
mand and the Arctic Environmental Research Station.
The EAFB, Northway and Ft. Greely lagoons are discussed primarily
in reference to effectiveness of multiple cells, short-
circuiting, sludge accumulation, and algae production. The Eagle
River and Palmer lagoons were included to allow comparison of two
full scale lagoons of different design, operating under similar
conditions.
The climate at EAFB, Northway, and Ft. Greely is very similar to
that of Fairbanks, which is located at 64 1/2 °N latitude. The
mean annual temperature at Fairbanks is approximately - 4 ° C . The
26
-------
sunshine varies from a winter low of approximately 3 3/4 hours
to a summer maximum greater than 22 hours. The Palmer and Eagle
River lagoons are located near Anchorage where the mean annual
temperature is about 2°C and the hours of sunshine vary from
5 1/2 hours in the winter to 19 1/4 as a summer maximum.
Biochemical oxygen demand (BOD), chemical oxygen demand (COD) and
suspended solids (S3) data (if available) are summarized for each
of the lagoons discussed. Winter and summer operation refers to
periods when the lagoon effluent temperature was less than 1°C
and greater than 10 ° C respectively.
"Fine bubble diffusers", as used hereafter, refer to restricted
diffusers such as the perforated tubing and porous ceramic types.
"Coarse bubble diffusers" refer to larger orifice types such as
the Aer-0-Flo or Shearfuser diffusers.
SAMPLING AND ANALYSIS
All analyses for the Eielson experimental Ft. Greely and Northway
lagoons were performed at the Arctic Environmental Research
Laboratory in accordance with Standard Methods, (1965, 1971).
Samples for the Eagle River and Eielson full scale lagoon were
collected by the Greater Anchorage Borough Public Works Depart-
ment and Eielson AFB personnel respectively and analyzed in ac-
cordance with standard methods. The Palmer lagoon samples were
collected by city employees and analyzed with Hach field eguip-
ment .
27
-------
Eielson Air Force Base Experimental Lagoon
Eielson plant lagoon feed samples were 24-hour composites col-
lected with a surveyor sampler supplied by N-Con Systems Company,
Inc. Cell samples were grab and were collected by means of a
pump through insulated and heat-taped tubing which entered each
cell at mid-depth and extended approximately 1 foot into the li-
quid. Samples were generally collected once per week and
analyzed for pH, BOD (5-day, 20°C), COD, solids and coliform in-
dicators. Nutrient samples were collected once per month. Each
sample line was flushed before collection. The samples were im-
mediately placed in an ice chest and returned to the laboratory
within 2 to 3 hours for analysis the same day. COD and nutrient
samples were occasionally preserved by freezing for later
analysis.
Problems were encountered during the last few months with
plugging of the cell 5 sampling tube. As a result, some samples
were missed and those that were collected appeared to give low
results. These were not included in the data analyses.
Fort Greely Lagoon
Nearly all of the Ft. Greely influent samples were collected
using a composite sampler. An N-Con Systems Company trebler
oscillating scoop proportional sampler was originally utilized
in the Palmer Bowlus flume before the lift station but was aban-
28
-------
doned because of fouling by large solids particles. A home-made
sampler was then constructed which consisted of a container with
an inlet tube which was placed in the splitter manhole. Each
time the lift pumps operated, liquid would rise above the inlet
tube and run in the collection container during the short period
the pumps were in operation. This proved to be an improvement
because the solids were largely pulverized by the lift pumps
before reaching the splitter manhole.
All effluent samples were grab. Each sampling operation required
at least two days. The general procedure was to drive to Ft.
Greely in the evening two days before sampling or in the early
morning one day before, in order to set up the influent sampler
to obtain a 24-hour composite. Sampling was then accomplished
in the early morning on sampling day, packed in an ice chest, and
driven back to the laboratory for analysis the same day, usually
within 3 to 5 hours. Analysis included BOD, COD, solids and
nutrients. pH was performed in the field with a Porto-matic,
Model 175 meter supplied by Instrument Laboratories. Dissolved
oxygen (D.O.) levels were obtained in the field with a Model 54
meter supplied by Yellow Springs Instrument Company. The D.O.
instrument was calibrated before leaving the laboratory in
saturated water at the expected lagoon temperature and the
calibration checked on return from the sampling trip. During the
cold weather, the instrument was kept in a specially fabricated,
insulated box while obtaining the lagoon D.O. levels.
29
-------
Northway Lagoon
Northway lagoon effluent samples were also grab while the in-
fluent samples were composite. The composite samples were ob-
tained from a tap in the discharge line from the lift pump. Each
time the lift pump operated, a small amount of sample was forced
through tubing into a collection container. Generally, the same
procedure was followed for Northway lagoon sampling as for Ft.
Greely. Samples were collected in the early morning, packed in
an ice chest and transported back to the laboratory for analysis
the same day. Because of the longer distances involved, a lag
of 6 to 9 hours normally occurred between collection and
analysis. Analyses were essentially the same as for Ft. Greely.
EIELSON AIR FORCE BASE EXPERIMENTAL AERATED LAGOON
Lagoon Description
The EAFB experimental lagoon (Figure 1) consisted of six cells
operated in series. During the latter part of the study the
lagoon was converted to four cells operating in series. It was
fed raw domestic sewage. The lagoon consisted of a wood crib
structure with vertical sides and lined with a 20 mil polyvinyl
*
chloride (PVC) membrane. Dimensions were 4.6m X 25.2m X 3.7m
deep for an operating volume of 420 m . Detention time per cell
was as follows:
30
-------
\t,4
Figure 1. Eielson Air Force Base Experimental Lagoon.
-------
Cell No. - 1 2 3 4 5 6 Total
Detention Time (days) - 1.8 2.9 3.6 5.4 7.3 9 30
Flow measurement and control was accomplished with a dump tank
and a timer on the feed pump and a "V" notch weir in the lagoon
effluent structure. In the lagoon, each cell was fed from the
previous cell through a 51mm diameter X 3m long suction hose
coiled and hung above the aerators. The feed temperature was a
fairly constant 20°C because of heated utilidors.
Initial startup of the lagoon began in September, 1968 with aera-
tion provided by fine bubble diffusers. These consisted of 16 mm
(5/8 in.) OD flexible plastic tubing with 8 slits per foot on top
and a lead keel on the bottom to keep it submerged (Hinde
Engineering Company, Highland Park, Illinois). The tubes were
placed perpendicular to the line of flow and supported 40 cm
above the bottom to prevent sludge plugging.
Because of clogging problems and resulting high compressor
discharge pressures encountered with the perforated tubing, the
lagoon was modified in January 1970 by replacing the tubing with
coarse bubble diffusers manufactured by Aer-0-Flow Corporation,
Florence, Kentucky. The lagoon was then operated through May
1972 (over two years) with no change in compressor discharge
pressure and no maintenance problems due to the aeration system.
32
-------
The Aer-0-Flow diffuser consisted of a cap which rested on a 1/8
inch pipe orifice. When air was flowing, the cap was forced up
about 1.5 mm and air flowed under the cap and, theoretically, up
through the small holes in the cap. When air was shut off, the
cap would fall back against the orifice and prevent solids from
backing up in the system.
Operation Problems
Clogging of the perforated tubing proved to be a problem during
the first year in the first two cells where the solids concentra-
tion was greatest. Cleaning was accomplished by applying hy-
drochloric acid at a rate of 50 g/m on one occasion and applying
hydrogen chloride gas at a rate of 9 g/m on three occasions.
Each time the compressor discharge pressure would drop to 0.50
2
to 0.56 kg/cm after cleaning and climb back to 0.63 to
2
0.70 kg/cm within a few days. Both cleaning methods were inef-
fective in the first two cells and replacement of tubing was
found necessary twice.
In the case of gas cleaning, adequate valving was not provided,
and the gas passed through the less restricted tubing in the last
4 cells restoring the aeration patterns in those cells but not
in the first two cells. Dissolved oxygen levels were generally
less than 1/2 mg/1 in the first two cells during this period.
33
-------
Problems were also encountered with leaking of the PVC liner
during the first summer's operation. Bentonite was added to the
first two cells in July and August and the lagoon pumped down in
•September 1969 when the leakage continued. Repairs to the lining
were made and the lagoon placed back in operation in October
1969. Some leakage still occurred which a further addition of
bentonite had stopped by late November 1969.
Minor leakage continued to be a problem and the lagoon was pumped
down during the summer of 1970 for more repairs to the PVC
lining. Leakage problems somewhat more severe were encountered
during the winter of 1970 - 1971; however, no attempts have been
made to adjust the data.
After installation of the Aer-0-Flo non-clog diffusers in
January, 1970, the compressor discharge pressure and temperature
2
immediately dropped from greater than 0.63 kg/cm and 90°C to
2
0.42 kg/m and 32°C, and the dissolved oxygen (DO) in the first
two cells rose to more than 5 mg/1. The lagoon was then operated
through May 1972 (over two years) using the Aer-0-Flo diffusers
with no change in compressor discharge pressure and no main-
tenance problems due to the aeration system.
BOD and SS_ Removals
A summary of BOD and SS removals for the EAFB experimental lagoon
is presented in Table 1. Removal data for both the perforated
34
-------
Table 1. Performance Summary of Eielson Air Force Base Experimental Lagoon
CO
en
Period Station
Six Cell Operation
First 18 Months Inf
Cell -1
-2
-3
-4
-5
-6
First Year Winter Inf
Fine Bubble Aeration Cell -1
-2
-3
-4
-5
-6
Second Year Winter Inf.
Coarse Bubble Aeration Cell -1
-2
-3
-4
-5
-6
Detention
Time (Days)
Per Cell
-
1.8
2.9
3.6
5.4
7.3
9.0
_
1.8
2.9
3.6
5.4
7.3
9.0
_
1.8
2.9
3.6
5.4
7.3
9.0
Accum.
-
1.8
4.7
8.3
13.7
21.0
30.0
_.
1.8
4.7
8.3
13.7
21.0
30.0
_
1.8
4.7
8.3
13.7
21.0
30.0
Loading
(^BODs/m3-day)
Per Cell
-
177.2
51.5
30.0
11.1
5.5
2.9
_
168.3
47.2
32.8
10.0
4.7
3.0
_
201.1
62.1
33.9
15.7
8.0
3.2
Accum.
-
177.2
67.8
38.4
23.2
15.2
10.6
_
168.3
64.3
36.5
22.1
14.4
10.1
_
201.1
76.8
43.5
26.4
17.3
12.1
Mean
319
151
108
60
40
26
26t
303t
137
118
54
34
27
28t
362
180
122
85
58
29
21
Stand
Dev.*
109
71
47
34
25
11
10
154-553
45
38
26
15
12
13
105
91
56
36
30
10
10
Number
Samples
40
55
58
56
56
51
58
9
17
20
18
17
17
19
21
21
21
21
21
15
21
BOD^
Percent
Per Cell
-
53
28
44
33
35
3
_
55
14
54
37
22
0
_
50
32
30
32
50
30
Removal
Accum
-
53
66
81
87
92
92
_
55
61
82
89
91
91
.
50
66
76
84
92
94
(Continued)
-------
Table 1. Continued
u>
01
COD
Period Station
Six Cell Operation
First 18 Months Inf
Cell -1
-2
-3
-4
-5
-6
First Year Winter Inf
Fine Bubble Aeration Cell -1
-2
-3
-4
-5
-6
Second Year Winter Inf
Coarse Bubble Aeration Cell -1
-2
-3
-4
-5
-6
. *
Mean
509
262
227
179
142
no
85t
315
249
242
164
129t
121t
112t
568
280
247
239
193
118t
81
Stand
Dev.*
175
106
87
84
83
61
38
176-464
64
77
55
57
55
41
103
71
97
80
87
44
40
Number
Samples
31
46
45
46
44
46
45
6
13
13
13
12
13
13
15
15
15
15
15
15
15
Percent Removal
Per Cell
-
49
13
21
21
23
23
_
21
13
33
21
7
7
_
51
12
3
19
39
32
Accum.
.
49
55
65
72
78
83
_
21
23
48
59
62
65
_
51
57
58
66
79
86
Mean
261
138
143
91
67
39
23+
218+
109
139
61
38
25
18
278
152
172
153
128
45+
23
Stand
Dev.*
128
46
86
67
69
29
12
112
42
63
27
18
10
10
131
51
99
74
82
16
10
SS
Number
Samples
42
58
58
61
55
56
59
11
18
18
18
17
14
17
21
21
21
21
20
21
21
Percent Removal
Per Cell
-
47
0
36
27
42
42
_
50
0
57
37
35
29
_
45
0
11
17
65
48
Accum
-
47
45
65
75
85
91
_
50
36
72
82
89
92
_.
45
38
45
54
87
92
(Continued)
-------
Table 1. Continued
CO
Detention
Time (Days)
Period Station
Si x Cell Operation
First and Second Inf
Year Winter Cell -1
-2
-3
-4
-5
-6
First and Second Inf
Year Summer Cell -1
-2
-3
-4
-5
-6
Per
1
2
3
5
6
7
1
2
3
5
7
9
Cell
-
.8
.9
.6
.0
.4
.5
_
.8
.9
.6
.4
.3
.0
Accum.
-
1.8
4.7
8.3
13.3
19.7
27.2
_
1.8
4.7
8.3
13.7
21.0
30.0
Load
(q BODs/r
Per Cell
-
192.
55.
32.
14.
7.
3.
_
118.
45.
23.
6.
4.
3.
8
5
5
2
3
7
9
9
6
3
5
3
ing
n3-day)
Accum.
-
192.8
73.8
41.8
26.1
17.6
12.8
_
118.9
45.4
25.8
15.5
10.2
7.2
Mean
347
161
117
71
47
28
24t
214
133
85
34
33
30
29
Stand
Dev.*
no
76
50
35
27
11
11
178-243
77-205
52-409
29-173
19-49
7-45
8-45
Number
Samples
30
38
41
39
38
32
40
3
5
4
4
5
5
5
BOD,
Percent Removal
Per Cell Accum
-
54
27
39
33
27
5
_
38
36
61
0
11
2
-
54
66
79
86
92
93
_
38
60
84
84
86
86
(Continued)
-------
Table 1. Continued
CO
oo
COD
Period Station
Six Cell Operation
First and Second Inf
Year Winter Cell -1
-2
-3
-4
-5
-6
First and Second Inf
Year Summer Cel 1 -1
-2
-3
-4
-5
-6
Mean
496
265
245
204
169
122
99
360
200
170
137
81
71
66
Stand
Dev.*
156
69
87
79
86
58
55
334-404
99-243
42-292
62-188
30-190
44-99
43-80
Number
Samples
21
28
28
28
27
28
28
3
4
4
4
4
4
3
Percent Removal
Per Cell
-
47
8
17
17
28
19
_
44
15
20
41
12
8
Accum.
-
47
51
59
66
75
80
_
44
53
62
78
80
82
Mean
264
132
157
110
87
36(t)
21
192
137
72
30
25
27
25
Stand
Dev.*
136
51
85
74
76
16
10
95-338
87-192
28-173
16-43
11-45
10-45
10-41
SS
Number
Samples
32
39
39
39
37
35
38
4
4
6
6
6
6
6
Percent Removal
Per Cell
-
50
0
30
22
58
42
_
29
47
59
17
0
9
Accum
-
50
41
58
67
86
92
_
29
63
85
87
86
87
(Continued)
-------
Table 1. Continued
Detention
Time (Days)
Period Station
Four Cel 1 Operation
Third and Fourth Year Inf
Cell
-
Third and Fourth Year Inf
Winter Cell
-
Third Year Summer Inf
Cell
-
-2
-4
5 & -6T
-2
-4
5 & -el
-2
-4
5 & -6T
Per
_
4.
9.
16.
_
4.
8.
13.
.
4.
9.
16.
Cell
7
0
3
7
6
9
7
0
3
Accum.
_
4.7
13.7
30.0
_
4.7
13.3
27.2
.
4.7
13.7
30.0
Loading
(q BOD5/m3-dayj
Per Cell
_
39.6
9.4
3.4
_
40.4
10.9
4.4
.
45.5
7.9
2.9
Accum.
-
39.6
13.6
6.2
—
40.4
14.2
6.4
„
45.5
15.6
7.1
BOD5
Mean
186t
85
55
33
190t
94
59t
40
214
71
47
19
Stand
Dev.*
61
26
28
15
74
21
20
11
56
17
22
10
Number
Samples
61
61
62
60
31
31
31
29
15
15
15
15
Percent
Per Cell
-
54
35
15
_
51
33
31
_
67
34
60
Removal
Accum
-
54
70
83
_
51
69
79
_
67
78
91
(Continued)
-------
Table 1. Continued
COD
Stand Number
Period Station
Mean
Dev.* Samples
Percent Removal
Per Cell
Accum.
Mean
Stand
Dev.*
SS
Number
Samples
Percent
Per Cell
Removal
Accum
Four Cell Operation
*
t
1
Third and Fourth Year Inf
Cell -2
-4 ,
-S&-6?
Third and Fourth Year
Winter Inf
Cell -2
-4
-5&-6I
Third Year Summer Inf
Cell -2
-4
-5&-6I
320
202
138
95
320t
215
162t
125t
317
165
94
47
The range is shown where the number of
Adjusted from probability plot.
Cell 5 Removals not shown due to
sample
98
69
65
47
no
38
52
30
76
44
44
5
62
60
62
61
32
30
31
31
15
15
15
15
samples collected is
collection
problems
-
37
32
29
-
33
25
19
_
48
43
18
-
37
57
70
-
33
49
61
_
48
70
85
145
90
54t
29
130t
101
69t
44
167
73
60
14
88
44
33
21
70
33
31
18
43
49
90
13
56
57
57
58
28
27
28
28
14
15
15
15
-
38
40
46
-
23
32
29
_
56
18
39
-
38
63
80
-
23
47
66
„
56
64
92
less than ten.
during this
period.
-------
tubing and Aer-0-Flo diffuser systems operated under essentially
the same conditions indicate little effect on process performance
by the change in aeration devices, (Figure 2). An exception is
the approximately 5 percent lower removals at around ten days
detention time associated with the coarse bubble diffuser. This
may have been due to a stirring up or shifting of the bottom
sludge caused by the change in aeration devices. Overall BOD
removal efficiencies for 4 cell and 6 cell operation are
presented in Figure 3 along with the maximum ice buildup ex-
perienced during the winter of 1970. The winter data, referred
to later, has been adjusted for average ice buildup using 1/2 of
the maximum thickness reported for each cell.
The much lower removal efficiencies for the 4 cell operation has
been attributed to a combination of aging due to sludge buildup
and the provision of fewer cells in series. Both of these con-
siderations are discussed later.
Winter and summer BOD removals and effluent SS levels are com-
pared in Figure 4. Best removals were obtained during the first
winter operation (6 cell) reaching greater than 90 percent at
around 20 days dentention. Summer removals for the first year ap-
proach those for the winter at less than 15 days and then level
off at around 86 percent. This can be ascribed to algae growth
since algae were present in cells 2 through 6 during that summer.
It should be noted that the first summer removals are based on
41
-------
100
90
80
O
cc
Q
O
CD
70
60
50
Fine Bubble Diffuser
o
Coarse Bubble Diffuser
10 15 20
Detention Time (Days)
25
30
Figure 2. EAFB Experimental Lagoon performance with fine bubble and coarse
bubble diffuser systems.
42
-------
100
90
80
o
E
o>
cr
o
00
70
60
50
T
Maximum Ice Thickness
Winter 1970
j
5
4
3
cu
10 20
Detention Time (days)
30
Figure 3. EAFB Experimental Lagoon performance with 6 cell and 4 cell
operation.
43
-------
100
90
80
a;
>
o
a>
a:
Q
O 70
CD 'U
60
50
100
80
cr>
I 60
cn
I 40
o
oo
1 20
c
a>
CL
0
o
a
6 Cell winter
6 Cell summer
4 Cell winter
4 Cell summer
10
Detention Time
20
30
Figure 4. EAFB Experimental Lagoon winter and summer percent BOD removal
and SS remaining vs. detention time.
44
-------
5 data points only. The reduced BOD removal efficiency during
summer is not considered the result of bottom sludge activity
during the first year but may have been the result of a reduced
degree of settling. Examination of the bottom sludge in cell 6,
during the fall of 1969, indicated only a thin layer of floc-
culated algae.
The 4 cell summer data shows lower removals at approximately 15
days but increases to greater than 90 percent at 30 days. The
lower removal at 15 days is attributed to aging of the lagoon
while the greater removals at 30 days are attributed to a fil-
tering action. The liquid in cells 5 and 6 of the EAFB lagoon
was dark green with algae during June and part of Duly 1971.
Chlorella appeared to be the predominant algae species. Green
filamentous growth was also thick with stringers over 10 feet
long attached to feeder air lines. During July a reduction in
color was accompanied by the appearance of Daphnia. Effluent
BOD's of less than 10 ppm were measured in late July and early
August and were attributed to the Daphnia and the filtering ac-
tion of the filamenmtous algae. Increased settling may also have
contributed to the higher removals.
Algae Growth
Chlorophyll measurements were made on the lagoon in the early
summer of 1969 (Figure 5). The highest chlorophyll reading in
the 6th cell was 810m-SPU/m3 (mil 1i-Specific Plant Units/meter
45
-------
600
500 -
400 -
Q_
CO
300 -
CL
o
o
x- Suspended
s Solids
- 100
200 -
100 -
cr>
^E
to
"o
CO
-o
cu
Q.
CO
3
CO
10 20
Detention Time (days)
Figure 5. EAFB Experimental Lagoon chlorophyll and suspended solids vs.
detention time.
46
-------
cubed). The major algae growth began after approximately 10 days
detention time and followed a typical growth curve. Information
is available for only 30 days detention time and followed a
typical growth curve, but presumably the curve would peak and
begin to decline with time.
Coliforms
Fecal indicator organisms measured in the effluent of the EAFB
6 cell, 30 day lagoon during the summer of 1969 were (Clark et
al . , 1970):
JULY AUGUST
Total coliform 5500 1200
Fecal coliform 440 770
Fecal enterococci 126 64
Associated effluent temperatures were 15 - 16°C and the pH varied
from 7.0 to 8.4.
Total coliform removals found in the EAFB experimental lagoon are
presented in Table 2. As Expected, the dieoff of coliform bac-
teria is significantly more rapid in the summer. The 6 cells in
series also resulted in higher dieoff rates than the 4 cells in
serie s .
47
-------
Table 2. EAFB Experimental Lagoon Total Coliform Removal Results*
-Pi
CO
Cell Number
Period Influent
Six Cell Operation
Winter
1/22/70-3/25/70 6.5 X 107
% Removal
Four Cell Operation
Winter
1/29/71-3/24/71 &
1/5/72-3/29/72 7.3 X 107
% Removal
Four Cell Operation
Summer
6/9/71-9/8/71 1.1 X 108
% Removal
1
1.3X107
80
1.2X107
84
8.2X106
93
2 3
6.7X106 4.1X106
90 94
1.8X106
98
3.9X106
99.6
4 5
1.4X106 3.0X105
98 99.5
1.1X106
98
2.2X104
99.98
6
1.4X10"
99.98
* Values are geometric means
-------
Nutrients
Nutrient removals for the EAFB experimental lagoon show little
removal of NH_-N or T-N during winter operations and significant
removals in summer (Table 3). T-N removals in summer were less
than NH,-N, indicating a conversion of nitrogen to the organic
form by algae. The phosphorus data indicate the net annual
removals are zero. The phosphorus apparently had previously ac-
cumulated in the bottom sludge and was being released to the
lagoon liquid by anaerobic action. Also the inherent inaccuracy
of the organic phosphorus analysis may have contributed to the
negative removal results.
FORT GREELY LAGOON
Lagoon De scr iption
Because of the success with the Aer-0-Flo diffusers in the pilot
facility, it was decided they should be demonstrated in a full
scale lagoon. This led to an agreement with the U.S. Army,
Alaska (USARAL), in the summer of 1971 which allowed AER5 to
modify part of the waste treatment lagoon at Ft. Greely.
The Ft. Greely lagoon was constructed in 1969 and had two cells
which could be operated in series or in parallel. Each cell was
separated into two smaller cells by a baffle which extended from
the bottom to about 0.3 m below the water surface. The lagoon
49
-------
Table 3. EAFB Experimental Lagoon Nutrient Removal Summary
Period
Six Cell Operation
Winter
% Removal
Summer
% Removal
Four Cell Operation
Winter
% Removal
Summer
% Removal
Station
Inf
Cell -1
-2
-3
-4
-5
-6
Inf.
Cell -1
-2
-3
-4
-5
-6
Inf
Cell -2
-4
-6
Inf
Cell -2
-4
-6
HN3-N (mg/1)
16
15
15
17
17
17
17
(-6)
29
25
28
27
26
20
15
48
14
20
22
20
(-43)
24
28
25
15
38
Nutrient
T-N (mg/1)
22
21
21
26
26
22
21
5
38
32
33
32
28
30
33
13
19
27
28
26
(-37)
30
27
26
25
13
0-P (mg/1)
6
8
8
9
9
9
10
(-67)
29
36
36
39
37
37
38
(-31)
7
12
10
11
(-57)
8
6
10
11
(-38)
T-P (mg/1)
10
13
14
15
14
15
16
(-60)
44
49
50
48
47
46
41
7
9
13
13
13
(-44)
10
12
10
13
(-33)
50
-------
was of earthen dike construction lined with PVC film and had 15cm
of sand covering the bottom. The upper slope was covered with
gravel. Each principal cell measured 61m x 61m at the base. The
side slope ratio was 2 horizontal by 1 vertical. Volume was
29,000 m at an operating depth of 3 m. The lagoon treated
domestic sewage which has a fairly constant temperature of 20°C
because of heated utilidors.
The aeration system of one half of the lagoon was modified in
Duly 1971 (Figure 6). Two clusters of Chicago Pump Shearfusers
(Chicago Pump, FMC Corporation, Chicago, Illinois) were installed
in one cell (Figure 7). Shearfusers consist of a box about 18 cm
square with a 2.5 cm air injection orifice entering the side. As
the air rises in the box, water is pulled in through the hole in
the other side and the resulting shearing action causes the air
to break up into smaller bubbles. Aer-0-Flo diffuser clusters
were installed in the second cell (Figure 8).
The two principal cells of the lagoon were operated in parallel
for one year beginning in October of 1971.
Aerator Performance
Figure 9 gives information on the perforated tubing aerator per-
formance. Some of the variability of the data is due to clogging
problems encountered with the perforated tubing. That is, as the
tubing began clogging, more air was diverted by the operator to
51
-------
CJl
ro
^
\N
\
x- —
k-^)
•N.
^
-
-
-
/
.
I
C
,4
1
^l
^
•-•>,
(
\
.. — •
(T
vi
^
d
L_ _
X.
\J
-e>- -
— 1
7)
•° 1
1
1
1
i
1
®|
__i
y
— x_
)
i,'
/
ft!
r
V
Iflf
X
f^i
«-^
•fri~
viy
— —
T)
J^
x^
s
]
k
1
s
/•
V
-®
\
/
fl
y
a
0
7
R
5
^Q\
O
1
7
i
°nn'
o'
»
• 1
g
a
y
3
8
© r
3
0
X
~"""**x^
^
-w
M
^^^
^/
^-PS'-**
N
\
/
/
\
\
/
/^
2
?(
2
LEGEND
1 Laboratory Building
2. Manhole -Parshall
Flume
3. Wet Well and Lift
Station
4. Chlorine Contact
Chamber
5. Effluent Line
6. Influent Header
7. Air Header Box
8. Aeroflow Diffusers
9. Shearfusers
10. Baffle
II. Dock
30'
5'
k
Figure 6. Plan view of Ft. Greely coarse bubble aerator installation.
-------
en
co
Figure 7. Chicago Pump Shearfuser cluster.
-------
tn
Figure 8. Aero-0-Flo non-clog diffuser cluster.
-------
o
I I I I I
I I I I I
I I I I I I I
I I I I I I I
I I I I
100
75
k_
O C(-v
O 2^ 3U
-^ 25
0
i I I I I I I
I I I I
Q.
E
c
o
o
01
o
20
10
0
' ' ' ' '
Oct Nov Dec Jan Feb Mar Apr May June July Aug Sep
Figure 9. Ft. Greely fine bubble diffuser performance data.
55
-------
the coarse bubble aerator side to reduce the discharge pressure
of the compressors. The trend was detected three months after
startup of the lagoon. Although the discharge pressure ranged
2
around 0.63 kg/cm in May, the air flow through the perforated
tubing was so low that the lagoon became anaerobic. The tubing
was cleaned with hydrochloric acid around the first of June. The
cleaning plus algal activity accounts for the high DO levels
during that month. Air flow data was not obtained in early July.
The low DO level which occurred in July was not due to low air
flow but to bottom sludge turnover. This turnover was caused by
heavy sludge layers which underwent increasing anaerobic action
as the temperature increased until the resulting gas production
caused the sludge to rise and disperse anaerobic products (or-
ganic acids, etc.) into the aerobic liquid above. The result was
a drastic decline in algae and a great increase in DO uptake
which reduced the lagoon DO level to zero. This lasted for a few
days after which time the DO level began to increase. This
phenomenon usually occurs each year after spring breakup in an
aerated lagoon in which sludge accumulates with little decomposi-
tion over the winter months.
Figure 10 presents performance information for the coarse bubble
diffuser side of the lagoon. The liquid temperature and ice
cover were about the same as for the perforated tubing side ex-
cept the ice cover did not reach 100 percent. Ice thickness in
56
-------
o
§•.§
12
10
8
^ 1.0
ro
M—
. O 0.8
< O 0.4
0.2
100
75
o>
8 & 50
CD
.2 25
0
I l I
I I o I I
l l i i i i i i i i i i
i i i i i i
Q.
E
20
10
0
I I l I I l J
Oct Nov Dec Jan Feb Mar Apr May June July Aug Sep
Figure 10. Ft. Greely coarse bubble diffuser performance data.
57
-------
both lagoons was never more than a few inches. The air flow to
the coarse bubble diffusers increased during the period of
clogging of the perforated tubing. The low DO point in early
Dune was again due to the sludge turnover phenomenon. The low
DO point in August occurred when the first 16 lengths of per-
forated tubing at the influent were manually cleaned (reper-
forated) with sharpened screwdrivers. This method of cleaning
reduced the pressure drop through the tubing to such a degree
that the system required rebalancing of air flow between the
coarse bubble diffusers and the perforated tubing.
Winter and summer aeration patterns for the coarse and fine
bubble aerators are shown in Figures 11 through 14.
BOD and 55 Remov als
A summary of the lagoon performance is included in Table 4. The
difference in detention times was due to an imbalance of flow to
the two sides. Very little difference in removals between the
coarse and fine bubble diffuser sides is indicated in spite of
the difference in detention times and loadings. An exception was
the higher effluent 55 for the coarse bubble side effluent,
presumably due to higher algae production for that side. A
somewhat higher mixing rate caused by the course bubble diffusers
may also have contributed to the higher 55 values.
58
-------
CJ1
vo
Figure 11. Fine bubble diffuser summer aeration pattern.
-------
CTi
O
Figure 12. Fine bubble diffuser winter aeration pattern,
-------
Figure 13. Coarse bubble diffuser sunnier aeration pattern.
-------
en
l\3
Figure 14. Coarse bubble diffuser winter aeration pattern.
-------
Table 4. Performance Summary of Ft. Greely Aerated Lagoon
Detention
Time (Days)
Period Station
Third and Fourth Years Inf
Coarse
Fine
en
co Third Year Winter Inf
Coarse
Fine
Fourth Year Summer Inf
Coarse
Fine
Per Cell
26
39
.
25
38
_
29
43
Accum.
26
39
.
25
38
_
29
43
Loading
(q BOD,/
Per Cell
7.3
4.9
.
7.6
5.0
_
6.6
4.5
m3-day)
Accum.
7.3
4.9
.
7.6
5.0
„.
6.6
4.5
Mean
190
39
37
189
37
33
192
43
45
Stand
Dev.*
137-274
24-72
27-56
164-204
25-48
27-39
137-274
24-72
34-56
Number
Samples
9
9
9
6
6
6
3
3
3
BOD 5
Percent Removal
Per Cell Accum
80
81
.
80
82
_ _
78
77
(Continued)
-------
Table 4. Continued
CT>
COD
Period
Third and Fourth Years
Third Year Winter
Fourth Year Summer
Station
Inf
Coarse
Fine
Inf
Coarse
Fine
Inf
Coarse
Fine
Mean
358
125
120
342
117
114
352
143
138
Stand
Dev.*
61
26
15
254-407
102-128
100-127
276-424
97-211
125-159
Number
Samples
15
15
15
9
9
9
4
4
4
Percent Removal
Per Cell Accum.
65
67
_
66
67
. —
59
61
Mean
153
47
41
146
38
30
161
73
57
Stand
Dev.*
29
28
15
110-170
19-51
26-49
97-218
42-141
33-78
SS
Number
Samples
15
15
15
9
9
9
4
4
4
Percent Removal
Per Cell Accum
.
69
73
-
74
75
-
55
65
The range is shown where the number of samples collected was less than 10.
-------
51udge Accumulation
Sludge depth measurements were made on the coarse bubble side of
the Ft. Greely lagoon in July 1971 while the lagoon was drained
for modification. Sludge accumulation over the perforated tubing
near the influent averaged about 50 cm along the influent
manifold and tapered to a depth of 5 cm approximately 15 m from
the influent edge of the lagoon. The remainder of cell 1 was ap-
proximately 15% covered with 3 - 5 cm of sludge. The second cell
was approximately 50% covered with 3 - 5 cm of sludge.
Sludge core samples were taken near the influent manifold at
various times during the project (Table 5). The core samples ap-
peared to be preserved essentially as deposited and were well
compacted which may account for the relatively high percent
solids.
Two temperature probes were placed in the sludge near the in-
fluent manifold at approximate depths of 18 cm and 48 cm. The
sludge depth at this point was 50 cm. The sludge temperatures
recorded along with the lagoon liquid temperature are shown in
Figure 15. The probe at 18 cm in depth ceased functioning after
the May measurement. The high temperature recorded in May is
probably due to high influent temperatures which remained at 20°C
or greater throughout the project. Sufficient gas had ac-
cumulated to cause sludge turnover to occur about July 10.
65
-------
Table 5. Ft. Greely Aerated Lagoon Sludge Analysis
Near Influent -
cr>
cr>
Date
12/21/71
5/19/72
6/16/72
11/30/72
Bottom
% Total
Solids % Volatile
6
-
20
67
-
40
Cell 1
Middle
% Total
pH Solids % Volatile
5.6 19
31
5
5.6
47
40
54
-
Near Effluent
Top
% Total
pH Solids % Volatile
5.9 21
22
17
53
58
50
9
5
Cell
* Total
pH Solids
6.3
1
6.0 31
1
% Volatile
~
69
19
Near Effluent
Cell 2
% Total
pH Solids
_ _
37
67
% Volatile
~
10
3
PH
~
-
-
-------
cr>
22
20
o
16
14
.0
12
S 10
Q.
o>
8
0
i r
Sludge Depth - 50cm
o Approx. 2cm Above Bottom
^ Approx. 33cm Above Bottom
• Liq,uid Temperature
Nov Dec ' Jan Feb Mar Ap May June July Aug Sept Oct Nov Dec
Figure 15. Ft. Greely aerated lagoon sludge and liquid temperature, 1971-1972.
-------
As expected, the sludge temperatures lag the liquid temperatures
and do not peak as high in the summer. The deeper sludge did not
reach a sufficiently high temperature for anaerobic decomposition
until late May and June , even with the high temperature influent
at Ft. Greely. The period of higher temperatures lasts for 3 or
4 months at the most.
Algae Growth
The variation of suspended solids and algae during the summer
season for the Ft. Greely lagoon is shown in Figure 16. These
values are for the coarse bubble side effluent and are very
similar to the fine bubble side values. In both cases the algae
levels built up very high during June and decreased sharply after
the bottom sludge turnover which occurred in early July. As may
be expected, the filtered BOD levels show that good effluent
quality can be obtained if algae removal can be accomplished.
Nutrients
Ft. Greely lagoon nutrient removals follow a pattern similar to
those for the EAFB Experimental lagoon. Winter NH,-N and T-N
values show no change through the lagoon and summer operation
shows significant removal (Table 6). The phosphorus data shows
no net reduction.
68
-------
500|-
4001-
3001-
o Unfiltered BOD (mg//)
Filtered BOD (mg//)
n Chlorophyll (m-SPU/m3)
SS (mg//)
200 h-
July Aug
Sample dates
Nov
Figure 16. Ft. Greely aerated lagoon BOD, chlorophyll and suspended solids
vs. summer sampling dates.
69
-------
Table 6. Ft. Greely Lagoon Nutrient Removal Summary
Nutrients
Period Station NH^-N
Winter Inf 15
Coarse 16
% Removal (-7)
Fine 16
?o Removal (-7)
Summer Inf 16
Coarse ID
?o Removal 38
Fine 12
% Removal 25
T-N
22
22
0
21
5
21
14
33
16
24
0-P
6
9
(-50)
8
(-33)
3
7
(-133)
7
(-133)
T-P
9
9
0
9
0
7
8
(-14)
8
(-14)
NORTHWAY LAGOON
Lagoon Descript ion
The Northway Lagoon consists of a wood crib structure with ver-
tical sides and sealed with bentonite. Dimensions are 12.8 m X
16.5 m X 2.3 m for an operating volume of 480 m .
A longitudinal baffle splits the lagoon into two equal cells,
each 6.4 m wide. Feed consisted of domestic sewage from the
Federal Aviation Administration (FAA) station, comprising 14
family units. The feed temperatures were estimated to vary from
2 - 24°C.
70
-------
The lagoon was placed in operation during September 1965 using
the perforated plastic aeration tubing. In September 1970, one
Air Gun aerator (Aero-Hydraulic Corp., Montreal, Quebec) was in-
stalled in each cell. These air guns consist of a 30.5 cm
diameter by 1.5 m long submerged vertical plastic pipe with an
air chamber at the lower end. Air is pumped into the chamber and
builds up until released by a siphoning effect through the tube.
The rising air bubble "piston" draws in water from holes in the
pipe located just above the air chamber and a pumping action oc-
curs. Air gun aerators are designed for use in deeper lagoons
(4 - 5 m) and are designed to provide mixing as well as oxygena-
tion .
The air gun aerators had been furnished by the manufacturer on
a loan basis and had to be returned during the summer of 1972.
Rather than attempt to rejuvenate the perforated tubing, pipe
stub nozzles were placed in the lagoon and connected to the air
headers. A check in October 1972 indicated the DO levels in the
lagoon to be near saturation, and the total detention time to be
about 25 days.
BOD and Sjs Removals
Overall BOD removal from the third through the eighth year was
approximately 86 percent which compared very well with the other
lagoons investigated (Table 7). A comparison of the third and
71
-------
Table 7 . Performance Summary of Northway Aerated Lagoon
ro
Period
Third through Eighth Years
Third Year
Eighth Year
Third through Eighth Year
Winter Period
Detention
Time (Days)
Station
Inf
Cell -1
-2
Inf
Cell -1
-2
Inf
Cell -1
-2
Inf
Cell -1
-2
Per Cell
_
20.0
20.0
_
22.0
22.0
_
14.5
14.5
_
12.3
7.7
Accum.
_
20.0
40.0
_
22.0
44.0
_
14.5
29.0
_
12.3
20
Loading
(g BOD^/m3-day)
Per Cell
.
13.1
2.6
.
10.8
2.6
_
14.7
2.3
_
24.2
7.8
Accum.
_
13.1
6.5
_
10.8
5.4
_
14.7
7.3
_
24.2
14.9
Mean
261
51
37
238
56
30t
213
34
31
297
60
49
Stand
Vev.*
73
17
15
140-330
34-82
13-67
198-228
30-38
19-52
195-380
42-82
24-67
Number
Samples
11
13
19
4
5
7
2
2
6
6
7
8
BODs
Percent Removal
Per Cell
„
81
27
_
76
47
_
84
9
_
80
18
Accum
_
81
86
_
76
87
_
84
85
.
80
84
(Continued)
-------
Table 7. Continued
CO
COD
Period
Third Through Eighth
Years
Third Year
Eighth Year
Third through Eighth
Years
Winter Period
Station
Inf
Cell -1
-2
Inf
Cell -1
-2
Inf
Cell -1
-2
Inf
Cell -1
-2
Mean
479
150t
136t
405
208
168
502
158
116
469
150t
147t
Stand
Dev.*
130
26
32
237-542
97-406
118-231
484-520
150-165
76-146
237-691
120-406
118-231
Number
Samples
10
10
14
3
3
3
2
2
6
6
6
7
Percent Removal
Per Cell
69
9
_
49
19
_
69
26
_
68
2
Accum.
69
72
_
49
58
_
69
77
_
68
69
Mean
206
61 1
39t
164
104
30
151
53
29t
233
63t
47t
Stand
Dev.*
130-353
49-136
17
131-196
71-136
25-34
130-172
50-56
18-66
131-353
49-136
25-93
SS
Number
Samples
9
9
13
2
2
2
2
2
6
6
6
7
Percent Removal
Per Cell
_
70
37
_
37
72
_
65
45
_
73
25
Accum
„
70
81
_
37
82
_
65
81
-
73
80
* The range is shown where the number of samples collected is less than ten.
t Adjusted from probability plot.
-------
eighth years performance showed little aging effect over this
period. Detention time for this period averaged 40 days.
Bottom 51udge
Analysis of sludge samples from the Northway Lagoon are shown in
Table 8.
In 3une 1967 and March 1971, sludge core samples were examined.
The sludge appeared to be preserved exactly as deposited.
However, in August 1967 and May 1968, bottom samples had a
definite black appearance and the physical characteristics of
partially digested sludge. Methane production apparently oc-
curred during the summer of 1967 causing the sludge location to
shift between the August 1967 and May 1968 sampling dates. The
maximum bottom sludge temperature recorded at Northway was 19QC.
Samples taken at Northway during March 1970 indicate an average
sludge accumulation of approximately 15 cm in the first cell and
approximately 8 cm in the second cell. This indicates an ac-
cumulation rate of 2.5 cm per year for 4.5 years or approximately
255 liters per 1000 people per day, which is in the low range of
observed rates for stabilization ponds (Clark et al., 19?0). Due
to compaction, consolidation, and digestion the long range ac-
cumulation may be less.
74
-------
Table 8. Northway Aerated Lagoon Sludge Analysis
Cell 1 Cell 2
Date
03/30/70
03/17/71
05/24/72
10/06/72
Ave
% Total
Solids
13
9
12
12
12
% Volatile
44
44
67
45
50
COD
pH mg/g/ Dry Wt.
6.8 92
54
110
7.3 95
88
% Total
Solids
-
42
4
14
20
% Volatile
-
7
63
17
29
COD
pH mg/g Dry Wt.
-
44
34
7.6 59
46
-------
In late March 1970, a 5 cm diameter bottom sludge core sample
from the first cell, Northway lagoon, was sectioned and analyzed
for fecal indicator bacteria (Clark et al. 1970). The 23 cm core
was cut in three sections as follows: 7.6 cm bottom, 13 cm
middle, and 2.5 cm top layer.
MPN counts on a per wet gram basis were as follows:
No. of Organisms x 10
TOP MID BOTTOM
Presumptive total coliform 4.9 49 22.1
Confirmed total coliform 3.3 13 13
Fecal Coliform 2.4 4.9 3.3
Presumptive enterococci 13 221 172
Confirmed enterococci 13 221 172
It appears that the sludge located deeper in the core has a more
favorable environment for concentration and preservation of fecal
organisms even though the sludge temperature was less than 1°C.
Four additional sludge cores were taken. Three had pH readings
of 7.0 to 7.5 while only one had a pH of 5 to 6. The moisture
content averaged 90 percent.
Results from 2.5 cm diameter bottom sludge cores obtained from
both cells during March 1971 were as follows.
76
-------
MPN counts on a per wet gram basis were:
No. of Organisms x 10
Cell 1 Cell 2
Presumptive total coliform 130 1410
Confirmed total coliform 79 140
Fecal coliforms 3.3 insufficient media
Presumptive enterococci 130 94
Confirmed enterococci 33 94
Confirmed enterococci
(Counts/mg. volatile solids) 83 2300
As compared to 1970 the coliforms appear to be composed of a
smaller fraction of fecal coliforms. Also the enterococci level
appears to be much lower. The 1971 results indicate that the
sludge in cell 2 is well digested but still harbors many enteric
bacteria.
Nutrients
Nutrient removals for the Northway lagoon show essentially the
same results as the EAFB Experimental and Ft. Greely lagoons
(Table 9). The phosphorus was not affected and the total
nitrogen removal was insignificant.
77
-------
Table 9. Northway aerated lagoon nutrient removal summary
Northway Overall Feed
Cell 1
Cell 2
NH3-N
19
30
30
T-N
35
33
32
0-P
7
12
12
T-P
12
13
12
EAGLE RIVER LAGOON
Lagoon Description
The Eagle River Lagoon had two egual size principal cells which
could be operated in series or parallel. Each principal cell
measured 30 m X 12 m at the base and was divided into two smaller
cells by a baffle below the liquid surface. Total lagoon volume
was 9,500 m" at an operating depth of 4.6 m. The lagoon was con-
structed of an earthen dike with a side slope ratio of 2:1 and
a liner of butyl rubber. Aeration was provided by fine bubble
type Hydro-Ceramic diffusers which consist of PVC tube with
porous ceramic stones inserted 0.3 m apart. Each stone provides
2
about 0.6 cm of surface area.
The lagoon treated domestic waste and also served two laundry
facilities which contributed a significant portion of the load.
Feed temperatures ranged from around 5°C in the winter, to a max-
imum of 15°C during the warmer months.
78
-------
Operation Problems
Since the lagoon began operation, the aeration system has been
plagued with problems which have contributed to the poor perfor-
mance. Most of the problems occurred when the diffusers became
clogged and high pressures developed in the system. The glued
joints of the PVC piping have tended to pull apart or break and
a number of the porous stones have blown out. The system has
been described as fragile and unreliable (R. Hutson, personal
communication, 1976). Failures which occur in the winter cannot
be repaired until summer.
The lagoon was placed in operation in the late fall of 1971 with
only one side in operation. The second side was placed in opera-
2
tion in the spring of 1972. Blower pressures were at 0.56 kg/cm
2
at startup and gradually climbed to 0.91 kg/cm which forced
draining of that cell in July 1972 for inspection (Mike Pollen,
Personal Communication, 1972). On inspection the ceramic dif-
fusers were found to be clogged with a matting of lint, hair and
solids.
Cutting a cross-section of the diffuser showed small particles
of lint and hair imbedded in the diffuser to a depth of approx-
imately 3.2 mm. Direct applications of concentrated hydrochloric
acid and scraping removed a large portion of the material but
deeply imbedded material reguired cleaning of individual pores.
The material was felt to have been forced into the diffuser when
79
-------
the blowers were shut off for maintenance purposes, allowing
water to back up in the aeration system.
The diffusers were cleaned in the field by brushing and washing
with mild detergent soap. Blower pressures were at about
0.60 kg/cm2 in October 1972, and the system was performing satis-
factorily. By .June, the pressure had begun to build up again,
although not to the levels previously experienced. Visual obser-
vation had shown the aeration pattern was obviously deterio-
rating. The diffusers were cleaned at the end of June by in-
troducing toluene at a rate of 34 g/m and hydrochloric acid at
a rate of 189 g/m at the instruction of the diffuser manufac-
turer. The hydrochloric acid cleaning was effective since a good
aeration pattern was established and the blower pressure dropped
7
back to 0.56 kg/cm . The toluene cleaning was ineffective.
At this time the lagoon was drained and sludge deposits were
found as shown in Figure 17, The intensive aeration provided in
the first cell due to the high depth vs width ratio of the lagoon
forced sludge carryover to the other side of the baffle. Sludge
deposition occurred in a less intensive aeration area near the
effluent discharge pipe. The sludge layer was not compacted
(high percentage of water) and the level was at the bottom of the
effluent pipe or at 0.45 m.
80
-------
74'
co
134
100'
1
f
40'
.-Lesser si
V layer
13 rows
aeration
tubing
i i
10'
3' square
ing at baffle
bottom.
,47 rows of.
aeration tub-
ing.
f ^*"-^.
udge \
open-///;
// At
//
\
\ 1
i /
ii
ii
Effluent cover box
/
If JVIajor sludge \
/ \ layer \
^
Inlet-^
Wiiii'
:•::•':. '-'•
Duplicate
Aeration
System
/
Baffle
surfac
below liquid
e
Figure 17. Eagle River lagoon sludge blanket.
-------
In October, 1973 the flow pattern was changed from series to
parallel. In May, 1974 the flow pattern was changed back to
series with the result that very high suspended solids levels
were experienced in the effluent. These solids were apparently
resuspended by the relatively higher flows through the lagoon
cells during series operations.
One principal cell of the lagoon was drained during the summer
of 1974 for repairs to the aeration system and a portion of the
ceramic diffusers were replaced with Aer-Q-Flow aerators.
Similar repairs and replacement of aerators in the other prin-
cipal cell were completed in the summer of 1975. Initially the
cap on the new diffusers had a tendency to blow off at relatively
high air pressures. The manufacturer provided redesigned dif-
fusers for replacement which have operated very well (Richard
Hutson, Personal Communication, 1976).
BOD and SS Remov als
A summary of operating results beginning in September 1972
through March 1976 are presented in Table 10 and Figure 18. The
worst performance results occurred during the slimmer months and
were apparently due to four causes: algae production, changing
from parallel to series operation, performance of necessary
repairs during the warm summer months, and dumping of septic tank
wastes into the system.
82
-------
Table 10. Eagle River Aerated Lagoon Performance Summary
CO
CO
Period
Second Year Overall
Series Operation
Second Year Winter
Series Operation
Second Year Summer
Series Operation
Third Year Winter
Parallel Operation
Third Year Summer
Single Cell Operation
Fourth Year Winter
Series Operation
Fourth Year Summer
Single Cell Operation
Fifth Year Winter
Series Operation
Detention
Time (Days)
Station
Inf.
Eff. 18.2
Inf
Eff 16.6
Inf
Eff 19.4
Inf
Eff 17.8
Inf
Eff 9.2
Inf
Eff 17.3
Inf
Eff 6.9
Inf
Eff 10.9
Loading
(g BODr;/m3-day)
Per Cell Accum
10.2
8.6
11.0
8.4
13.5
9.1
21.9
17.5
BOD 5
Mean
185
38
142
29
213
49
149
50
124
55
158
36
151
78
191
41
Stand
Dev.*
79
20
51
8
89
27
45
11
86-162
25-78
47
16
59
25
113
13
Number Percent Removal
Samples
97
95
34
38
40
37
21
21
6
6
16
12
14
14
12
12
79
80
77
66
56
77
48
79
(Continued)
-------
Table 10. Continued
COD
Period
Second Year Overall
Series Operation
Second Year Winter
Series Operation
Second Year Surnner
Series Operation
CO
4=» Third Year Winter
Parallel Operation
Third Year summer
Single Cell Operation
Fourth Year Winter
Series Operation
Fourth Year Summer
Single Cell Operation
Fifth Year Winter
Series Operation
Station
Inf
Eff
Inf
Eff
Inf
Eff
Inf
Eff
Inf
Eff
Inf
Eff
Inf
Eff
Inf
Eff
Mean
507
149
350
113
587
195
492
214
436
314
582
190
482
443
444
192
Stand
Dev.*
208
52
103
13
236
53
148
22
337-521
237-345
193
52
212
129
201
43
Number
Samples
49
51
17
18
19
20
20
21
7
6
16
17
14
14
13
13
Percent Removal
71
_
68
_
67
.
57
.
28
.
67
_
8
_
57
Mean
237
56
149
30
292
88
198
71
197
150
226
60
196
252
141
59
Stand
Dev*
113
38
71
7
97
41
83
14
128-284
SS
Number
Samples
112
113
36
41
46
45
21
20
7
98-187 6
75
15
112
107
55
19
16
18
14
14
15
13
Percent Removal
.
76
_
80
_
70
_
64
_
24
_
73
(-29)
_
65
The range is shown where the number of samples collected is less than ten.
-------
Flow diverted to 1/2 of
lagoon for broken airline
repair
L-H/2 of lagoon drained
I for short period to
I repair airlines
(-Changed from series ,j,F|ow diverted to 1/2 of
to parallel operation r |agoon to insta|| new
Flow diverted to 1/2 of
lagoon to install new
diffusers
20
Back in normal
operation j
I
^
Changed from pa-
rallel to series
detention time-day
Effluent temperatu,re-°C
29IU32714,42
\ \t s •
M" ^
'V-^Effluent BOD-mq/J
I I I I I
Problem with
blower 81 broken
air heater in cell 4
S 0 N D J F
1972 |
JJASCTNDJFW
1973
MJJASONDJFM
1974
J J AS 0 N D J
1975 I
FM
1976
Figure 18. Eagle River lagoon operating results.
85
-------
A comparison of various phases of the lagoon operation indicates
that series operation is superior to parallel operation during
winter months (Table 10). A comparison of summer series and
parallel operation was not possible because of the need to do
repair work during these months.
There seems to be little difference in BCD removal efficiencies
from the second to the fifth year; however, the data does in-
dicate a decrease in COD and SS removals over this period. This
could be attributed to a lack of adequate sludge storage with the
result that bottom sludge is resuspended and carried out the ef-
fluent pipe .
The second year overall series operation was selected as a
typical full year's operation. The effluent parameters for that
year were plotted on probability paper (Figure 19). The plots
indicate the BOD and SS exceeded 30 mg/1 55% and 70% of the time,
respectively. The SS exceeded 70 mg/1 30% of the time.
Col iforms
The effectiveness of the Eagle River disinfection contact chamber
is shown in Table 11. The chamber is baffled so that the length
of liquid travel is 12.2 m. Chlorine gas is fed to the lagoon
effluent stream about 20 m before it enters the chamber.
The arithmetic mean and geometric mean of the coliform counts are
both shown. The chamber is most effective at nominal contact
86
-------
200
175
150
1 125
o
(S)
c
o>
Q_
cn
u
C/)
k_
o
Q
O
DO
c
-------
Table 11. Eagle River aerated Lagoon Disinfection Summary
Period
Second Year Winter
11/10/72-3/28/73
Second Year Summer
5/10/73-9/26/73
Third Year Winter
12/12/73-2/28/74
02 Third Year Summer
OT 7/25/74-9/6/74
Fourth Year Winter
11/21/74-3/25/75
Fourth Year Summer
6/4/75-9/4/75
Fifth Year Winter
12/2/75-2/25/76
Nominal Contact
Time (Min)
92
107
98
101
95
76
60
Chlorine
Residual (mg/1)
1.5
1.0
1.0
1.0
0.8
1.2
1.9
Total Coliforms
per 100 ml (Avg)*
1525 (221)
2037 (516)
922 (302)
790 (314)
6,100 (1938)
60,890 (8446)
27,800 (20,275)
Fecal Coliforms
per 100 ml (Avg)*
-
-
0.4 (1)
16.4 (9)
37.6 (12)
744 (39)
419 (139)
Numbev
of samp"
4
19
17
10
28
19
26
Value in parentheses = geometric mean
-------
times greater than 90 minutes with fecal coliforms exhibiting
less resistance to chlorination than total coliforms.
EIELSON AIR FORCE BASE FULL SCALE LAGOON
Lagoon Description
The Eielson Air Force Base Lagoon is similar in design to the Ft.
Greely Lagoon except that aeration is provided by Kenics
Aerators. The lagoon had two principal cells 30 m X 12 m at the
base which were egually divided into two smaller cells by a
baffle below the surface of the water. The total lagoon volume
was 56,030 m at an operating depth of 3 m. A chlorine contact
chamber of 81.4 m provided a contact time of 30 min. at
3,900 cu m/day flow. The lagoon receives effluent from the EAFB
primary treatment plant.
Operation Problems
During startup in November, 1973, the lagoon was filled with lake
water for testing purposes. When the aeration system began
operation, the combination of cold water and cold air resulted
in ice buildup on the aerators. The aerators, which were con-
nected to flexible air lines, plus the small concrete pads on
which they were mounted floated to the surface. The lagoon was
drained and the aerators returned to their original position.
The introduction of warm wastewater melted the ice and the aera-
tion system has since performed satisfactorily with no problems
(3im O'Neil, Personal Communication, 1976).
89
-------
The lagoon liner was brought to the top of the dike with no
gravel or rip 'rap covering. Tearing problems from ice movement
have not occurred in the main lagoon; however, patching of a
number of holes was necessary in the chlorine contact chamber
which was constructed in the same fashion as the main lagoon.
The holes were made by ice movement the previous winter- Separa-
tion at the seams of the main lagoon liner did occur during the
first winter's operation and these were repaired during May and
Dune, 1974. The liner manufacturer attributed the separations
to waste petroleum products in the wastewater. An alternate
cause may have been installation of the liner without sufficient
slack to account for contraction at colder temperatures.
BDD and 5_S Removals
Operating performance of the lagoon from January, 1974 through
April 1976 is presented in Figure 20. The results show evidence
of aging by the lagoon as the effluent quality for 1975-76 is
generally lower than for 1974. The highest effluent SS occurred
in June, 1974 when one-half of the lagoon was taken out of opera-
tion for repairs. Dumping of large amounts of septic tank sludge
apparently caused a high effluent BOD in September 1974,
Because of the frequency of changes in the lagoon operation which
occurred during the study period, a good comparison of series and
parallel operation was not possible (Table 12). The series
operation during the first summer appears to have improved the
90
-------
30
20
10
0
240'
200
160
120
80
40
0
-Changed from Parallel
to Series Operation
I /
Detention Time-days
Changed from Parallel to
^""Series Operation /•-
Lagoon No 1
-Drained for —
_Repairs to
Liner
-May 23-June 16
Received-20,000 Gal
Septic Tunk Sludge
within One Week Period
— Changed from Series to _f
Parallel Operation
A
Influent BOD-mg//
A
/Influent ss-mg//
/Effluent BOD-mg//
Effluent ss-
II
I I I
Jan Mar May July Sept Nov
I 1974
Jan Mar May July Sept Nov Jan Mar
! 1975 I 1976
Figure 20. EAFB full scale lagoon operating results.
-------
Table 12. Performance Summary of EAFB Full Scale Lagoon*
i-D
ro
Period
First Winter
Parallel Operation
First Summer
Parallel Operation
First Summer
Series Operation
Second and Third Uinter
Parallel Operation
Second Summer
Series Operation
Second Summer
Parallel Operation
First Uinter
Parallel Operation
First Summer
Parallel Operation
First Summer
Series Operation
Second and Third Winter
Parallel Operation
Second Summer
Series Operation
Second Summer
Parallel Operation
Detention
Time (Days)
Station
Inf
Eff 17.8
Inf
Eff 20.9
Inf
Eff 19.5
Inf
Eff 22.8
Inf
Eff 22.1
Inf
Eff 31.0
Inf
Eff
Inf
Eff
Inf
Eff
Inf
Eff
Inf
Eff
Inf
Eff
Loading
(q BOD ^/m^ -day)
Mean
136
7.8 35
137
6.6 30
137
7.0 22
158
6.9 52
139
6.3 79
133
4.3 55
80
37
81
31
84
21
74
41
64
36
73
43
Stand
Dev.t
31
15
124-155
13-49
77-175
11-30
48
13
109-223
10-163
14
15
15
10
71-97
19-44
72-61
10-61
28
8
57-79
19-52
15
8
BODS
Number Percent Removal
Samples
11
11
5
5
8
8
30
30
6
6
10
10
SS
11
11
5
5
9
9
30
30
6
6
10
10
74
78
84
67
43
59
54
62
75
45
41
43
* No COD's reported.
t The range is shown where the number of samples collected is less than ten.
-------
treatment efficiency. The poor second summer series operation
may have been caused by septic tank sludge as evidenced by the
high BOD levels compared t.o the SS levels. The septic tank
sludge was not accounted for in the influent parameter values.
Col iforms
Performance of the chlorination contact chamber was somewhat er-
ratic with the poorest performance occurring in June and July,
1975 (Table 13). The greatest concentration of algae may have
been produced at that time, however, the lowest rate of chlorine
feed also occurred during that period. In the original design
of the chamber, the chlorine feed line entered the pond next to
the chamber influent line. The chlorine feed was modified during
the spring of 1975 to enter the waste stream at the effluent col-
lection man hole which allows mixing in 6 m of pipe before en-
tering the contact chamber. This modification has improved the
chlorination effectiveness as evidenced by the winter parallel
data .
PALMER AERATED LAGOON AND POLISHING POND
Lagoon Descr iption
The original Palmer waste treatment system, which drained into
a facultative lagoon, was replaced in the summer of 1972 with an
aerated lagoon which also discharged to the facultative lagoon.
The aerated lagoon and the polishing pond were of earthen dike
93
-------
Table 13. EAFB Full Scale Lagoon Disinfection Summary
Nominal Chlorine Chlorine Fecal No. of
Period Contact Time (Min) Feed (mg/1) Residual (mg/1) Coliforms/100 ml*' Samples
Winter Parallel
11/19/74-02/11/75 37 - 0.7 1,994 (98) 6
11/04/75-02/24/76 42 6.6 0.6 17,260 (92) 16
Summer Series
06/03/75-07/08/75 37 4.4 0.3 0-TNCt 8
Summer Parallel
09/05/75-10/07/75 53 7.6 0.4 111 (29) 10
* Values in parantheses = geometric mean.
t Included 3 values of 0 and 4 TNC (too numerous to count).
-------
construction with a side slope ratio of 3:1 and sealed with ben-
tonite. Common dimensions of the aerated lagoon were
30 m X 220 m. The aerated lagoon volume was 24,600 m at an
operating depth of 2.7 m. Aeration was provided by perforated
tubing diffusers. The polishing pond area and volume were
2 3
17,846 m and 27,250 m respectively at an operating depth of
1.5m.
Operation Problems
The lagoon began operation in October, 1972 and has suffered from
relatively few operating problems, apparently due to the rela-
tively light loading on the lagoon, the overall design and the
excellent maintenance provided. Sludge which had accumulated in
the polishing pond before installation of the aerated lagoon oc-
casionally would rise to the surface after operation began. The
rising sludge did not create a nuisance and has not been observed
since the first year of operation.
Destruction of the aeration pattern by bottom sludge settling
near the influent line occurred in the aerated lagoon and the
system was drained for repair during the summer, 1975. About
0.6 m of sludge was found around the inlet pipe. The depth
tapered to a few centimeters at a distance of 6 m from the inlet
pipe. After the sludge had dried, a backhoe was used for removal
and the tubing replaced in that area. An additional aeration
device was placed near the influent line for the purpose of
95
-------
resuspending the bottom sludge so that recurrence of the problem
may be prevented. The effectiveness of the new device has not
been determined.
BOD and ^S Removals
Operating results are presented in Table 14 and Figure 21. The
data was supplied by the City of Palmer. Samples were collected
3 times per week by the city operators and pH, DO and tempera-
tures recorded and 55 determined. BOD analyses were made once
per week. BOD, DO and 55 analyses were performed with Hach Kits.
Polishing pond effluent dissolved oxygen levels have been in-
cluded in the graph as an indication of the polishing pond ef-
fects. As may be expected, the DO levels were high in the summer
due to algae action and low in the winter. The winter DO
measurements consistently leveled off at 2 mg/liter. DO levels
from the aerated ].agoon average about 8 mg/liter in the winter
which apparently maintain the 2 mg/liter level in the polishing
pond e ffluent.
The overall system has provided consistently good treatment with
little difference in winter and summer periods.
Aerated lagoon effluent data was collected from July 2 through
September 12, 1973, a period during which the polishing pond was
not in operation. The data indicated that the aerated lagoon by
itself attained 55?o BOD removal. When compared with 91% BOD
96
-------
Table 14. Performance Summary of Palmer Lagoon*
Det. Loading/day
Operation Station Time g/BODs/m-Yday Mean
Aerated Lagoon Only
07/02/73-9/12/73
Winter - Aerated Lagoon
plus Facultative Lagoon
01/07/74-04/01/74
12/04/74-03/28/75
12/01/75-03/31/76
Summer - Aerated Lagoon
plus Facultative Lagoon
05/17/74-07/17/74
08/09/74-09/09/74
Overall - Aerated Lagoon
plus Facultative Lagoon
.Inf 51.6
Eff 3.5
Inf 106.0
Eff 1.8
Inf 102.7
Eff 2.0
Inf 109.6
Eff 1.7
182
42
192
16
209
6
188
11
BODs
Std Devt
125-270
15-110
83
14
60
4
74
12
SS
# Samples
8
9
43
41
13
13
47
45
% Rem Mean
128
77 58
184
92 17
181
97 18
185
94 17
St. Dev
64
38
61
4
59
11
56
7
# Samples
32
28
141
141
41
41
156
147
% Rem
.
55
_
91
.
90
_
91
05/01/74-04/30/75
No COD's reported.
Range of values given for No of samples less than 10.
-------
OO
-Facultative lagoon under
repair-Aerated lagoon
treatment only
Facultative pond out of
operation for repairs 7/19-8/8
-Aerated lagoon drained for
repairs-No samples taken
110 days mean detention time
1 20.
\ fdetention tme-days
Effluent dissolved oxygen-
^Effluent temperature-°C
.^Influent BOD-mg/J
Influent SS-mq
Effluent SS-mq/J
Effluent BOD-mg//
f-30 mq/J
en
£
O
a
CL
AMJJASONDJ
1973
AMJJASONDJFMAMJJASONDJFM
1974 I 1975 I 1976
Figure 21. Palmer lagoon operating results.
-------
removal for the aerated lagoon-polishing pond combination, one
can infer that a significant amount of treatment is taking place
in the polishing pond.
The period from May 1, 1974 to April 30, 1975 was selected as a
typical full year's operation and plotted on probability paper
(Figure 22). The effluent BOD and SS exceeded 30 mg/1 10% and
4% of the time respectively. The effluent SS exceeded 70 mg/1
less than 1% of the time.
A major portion of treatment in the polishing pond is similar to
the treatment which occurs in the aerated cells, i.e., settleable
solids deposit under quiescent conditions and the settled sludge
undergoes anaerobic decomposition. Assimilation and oxidation
of organic matter and oxidation of biological solids occur at a
very reduced rate because concentrations have been reduced by
treatment in the aerated cells.
During summer months, algae removal occurs through sedimentation
and subsequent anaerobic decomposition and through consumption
by higher organisms. These various phases of treatment are
discussed in Section 7.
STUDIES BY OTHERS
To arrive at a more comprehensive picture of cold climate aerated
lagoon performance BOD and SS data on lagoons outside Alaska were
99
-------
50
40
CD
•O
C
CD
Q.
in
Q
O
QQ
c
CD
ZJ
Ld
30
20
10
0
i i i i r
Suspended
Solids
i i r . i
1 2 5 10 20 40 60 80 90 95 98
Time Less Than (%)
Figure 22. Palmer lagoon effluent BOD and suspended solids variability.
TOO
-------
incorporated in our analysis. These lagoons are in Eagan Town-
ship, Winsted and Redwood Falls, Minnesota (Breinhurst, 1970);
three lagoons near Winnepeg, Manitoba (Penman et al., 1970) and
a lagoon at Harvey, N. Dakota (Vennes, 1970).
The BOD and 55 removals obtained with these lagoons is summarized
in Tables 15 through 17. Fecal and total coliform results for
the Harvey, N. Dakota lagoon are also presented in Table 18.
101
-------
Table 15. Performance Summary of Minnesota Lagoons*
o
ro
Lagoon
Eagan, Minn
2nd & 3rd years
3rd Winter
2nd & 3rd Summer
Eagan, Minn
2nd & 3rd years
3rd Winter
2nd & 3rd summer
Station
Inf
Cell -1
-2
Inf
Cell -1
-2
Inf
Cell -1
-2
Inf
Cell -1
-2
Inf
Cell -1
-2
Inf
Cell -1
-2
Detention Loading
Time (Days) (g BODs/m3-day)
Per Cell Accum. Per Cell Accum. Mean
1225
7.0 7.0 175.0 175.0 225
8.4 15.4 26.8 79.6 113
1107
9.2 9.2 120.3 120.3 257
9.9 19.1 26.0 58.0 159
1324
5.5 5.5 240.7 240.7 178
6.8 12.2 26.2 108.5 116
764
823,
31 Ol
372
413
148
1069
1009
538
Stand
Dev.
880-1750
60
73
960-1255
222-290
44-218
880-1750
118-230
78
264-2110
302
180
273-446
300-545
33-220
330-1880
790-1220
529
Number
Samples
10
12
21
3
3
5
6
6
10
10
11
21
3
3
5
5
5
10
BODj.
Percent
Per Cell
-
83
50
_
77
38
_
87
35
SS
-
17
62
—
0
64
.
6
47
Removal
Accum
-
83
91
_
77
86
_
87
91
-
17
69
.
0
60
_
6
50
(Continued)
-------
Table 15. Continued
Detention
Time (Days)
Laqoon Station
Redwood, Minn
2nd Year Inf
Cell -1
-2
-3
2nd Winter Inf
Cell -1
-2
-3
o 2nd & 3rd Summer Inf
00 Cell -1
-2
-3
Winsted, Minn
2nd & 3rd Year Inf
Cell -3
3rd Winter Inf
Cell -3
2nd & 3rd Summer Inf
Cell -3
Per Cell
_
14.1
31.6
42.0
_
18.0
37.0
44.0
.
12.1
28.1
33.8
-
-
_
-
_
-
Accum.
14
45
87
18
55
99
12
40
74
74
68
74
_
.1
.7
.7
_
.0
.0
.0
.
.1
.2
.0
.
.0
_
.0
.
.0
(p
Per
_
12.
1.
0.
_
9.
1.
0.
.
12.
1.
1.
-
-
_
-
_
~
Loading
BOD5/m3-day)
Cell
0
2
8
3
4
3
9
3
0
Accum.
_
12.0
3.7
1.9
_
9.3
3.0
1.7
.
12.9
3.9
2.1
-
12.6
_
12.6
„
14.3
BOD 5
Mean
169,.
39*
32
15
167
51
15
9
156.
36f
34T
19
930t
62
857
75
loeol
57
Stand Number
Dev. Samples
38
11
17
7
170-215
50-52
10-23
8-11
100-225
26-165
13-68
6-33
450
42
540-1290
30-112
290-1990
7-125
12
11
12
20
3
2
3
5
6
6
6
9
12
19
3
5
6
9
Percent
Per Cell
_
77
18
54
_
70
71
40
.
77
8
44
-
-
_
-
_
~
Removal
Accum
_
77
81
91
_
70
91
95
_
77
79
88
-
93
_
91
_
95
(Continued)
-------
Table 15. Continued.
Lagoon Station
Redwood, Minn
2nd Year Inf
Cell -1
-2
-3
2nd Winter Inf
Cell -1
-2
-3
2nd & 3rd Summer Inf
Cell -1
-2
-3
Wins ted, Minn
2nd & 3rd Years Inf
Cell -3
3rd Winter Inf
Cell -3
2nd & 3rd Summer Inf
Cell -3
Mean
202
95
60
42
258
58
21
20
187
134
85
64
479
77
318
106
619
64
Stand
Dev.
41
50
32
27
215-334
48-68
16-25
14-38
146-232
86-172
59-110
25-107
197
55
243-358
46-170
340-835
7-150
Number
Samples
12
10
12
19
3
2
3
5
6
5
6
8
12
19
3
5
6
9
SS
Percent
Per Cell
-
53
37
30
_
78
63
7
_
28
36
26
-
-
_
-
_
—
Removal
Accum
-
53
70
79
_
78
92
92
_
28
54
66
-
84
_
67
_
90
* No COD's reported.
f Range of values reported for number of samples less than 10.
T Adjusted from probability plot.
-------
Table 16. Performance summary of Winnepeg lagoons.1
o
en
Operation
First & Second
Years Overall
(21 months)
First and Second
Winter
First Year
Summer
Series Operation
Jan, Feb, Mar,
1972
Station
Influent
Effluent
Air Aqua
Surface Aerator
Air Gun Aerator
Influent
Effluent
Air Aqua
Surface Aerator
Air Gun
Influent
Effluent
Air Aqua
Surface Aerator
Air Gun
Influent
Effluent
No 1 Secondary
Air Gun
Surface Aerator
Air Aqua 1
Air Aqua 2
Detention
Time
30
20
20
_
30
20
20
_
30
20
20
„
-
6.2
12.4
17.1
21.8
Loading
g BOD/m3-day
5.8
8.8
8.8
_
6.9
10.3
10.3
_
4.4
6.7
6.7
_
-
20.0
10.0
7.3
5.7
BOD
Mean
175
37
38
34
206
41
47
39
133
21
19
15
223
124
82
57
44
36
5
I Removal
79
78
81
_
80
77
81
_
85
86
89
_
-
34
54
65
71
SS
Mean
188
34
39
34
199
42
56
45
157
32
31
32
263
41
56
91
51
32
% Removal
82
79
82
_
79
72
77
_
80
80
80
_
-
(-37)
(-122)
(-24)
22
* No COD's reported.
-------
Table 17. Performance summary of Harvey, N. Dak. Aerated Lagoon.*
o
01
Period
1 st through 4th years
Winter 1st, 2nd and
4th years
Jan through Mar
Winter 3rd year
Jan through Mar
Summer 1st through
4th years
June through Sept
1st through 4th years
Winter 1st, 2nd and
4th years
Jan through Mar
Winter 3rd year
Jan through Mar
Summer 1st through
4th years
June through Sept
* No COD's reported.
t The range is shown where
1 Calculated from the data
Detention Loading
Time (Days) (g BODs/m3-day)
Station Per Cell Accum. Per Cell Accum.
Inf - - - -
Cell -1 20 20 13.2 13.2
-2 20 40 6.3 6.6
Inf - - - -
Cell -1 20 20 15.6 15.6
-2 20 40 6.5 7.8
Inf - - - -
Cell -1 20 20 33.3 33.3
-2 20 40 11.3 16.6
Inf - - - -
Cell -1 20 20 14.0 14.0
-2 20 40 4.7 7.0
Inf
Cell -1
Cell -2
Inf
Cell -1
-2
Inf
Cell -1
-2
Inf
Cell -1
-2
the number of samples is less than 10.
reported.
Mean
263
126
53
312
129
50
665
226
160
280
93
28
166
118
67
221 :
111-
72^
190:
187-
124-
185^
117-
71-
Stand
Dev.
134
76
45
180
10
23
950
65
19
117
28
23
118
74
39
: 152-316
58-172
32-104
; 100-322
• 100-524
90-160
: 114-312
40
: 37
Number
Samples
.
-
-
_
-
-
_
-
-
_
-
-
_
-
-
7
8
8
6
6
6
7
13
13
BOD5
Percent
Per Cell
52
58
_
59
61
_
66
29
_
67
70
VSS
.
29
43
_
50
35
_
2
34
_
37
39
Removal
Accum
.
52
80
_
59
84
..
66
76
_
67
90
.
29
60
_
50
67
_
2
35
_
37
61
-------
Table 18. Harvey, N. Dak Aerated Lagoon Fecal and Total Coliform Results
o
-xl
Jan-Mar (66,67,69)
% Removal
Jan-Mar (68)
% Removal
June - Sept (All)
% Removal
Feed
1.1 x 106
7.4 x 106
1.3 x. 107
Fecal Coliforms
Cell 1
6.0 x 105
45
2.5 x 106
66
1.3 x 106
90
Cell 2
7.9 x 104
93
1.0 x 106
86
1.0 x 10"
99.92
Jan-Mar (66,67,69)
% Removal
Jan-Mar (68)
% Removal
June - Sept (All)
% Removal
6.9 x 106
6.8 x 107
6.9 x 107
Total Coliforms
1.8 x 106
74
7.3 x 106
89
4.2 x 106
94
4.8 x 105
93
5.4 x 106
92
7.0 x 101*
99.90
-------
SHORT-CIRCUITING
Short-circuiting is one of the most important problems with
lagoons, with wind playing a major role (Barsom, 1973). Dye
studies were conducted on the Ft. Greely lagoon in order to gain
an idea of the degree of short-circuiting taking place for that
particular lagoon design.
The dye studies were conducted over 24 hour periods. Observa-
tions were recorded in terms of relative concentrations because
dye adsorption and decay could be expected to invalidate absolute
results .
The first test was made on the coarse bubble diffuser side but
had to be abandoned because of very high winds which developed.
Some information was gathered, however. One hundred fifty ml of
Rhodamine B dye was added at the splitter manhole. Evidence of
dye was seen at the first two inlets of the influent header after
2 minutes. The dye then began to drift toward the center baffle
near the dike with some mixing with the aerator cluster. The dye
*
continued to mix with the aeration cluster but also drifted over
the center baffle. Visible evidence of the dye was seen over
halfway into the 2nd cell along the dike. Short circuiting was
obviously taking place with the high winds making a major con-
tribution to the problem.
108
-------
Additional dye studies were conducted at a later date under
calmer wind conditions. The patterns of visible dye movement ob-
served are shown in Figure 23. Again the wind, although very
light, had a major effect on the apparent short-circuiting which
was taking place. Times required for the dye to reach the ef-
fluent are shown in Figures 24 and 25. The readings were taken
with a Turner fluorometer and are plotted as relative concentra-
tions. In this case 750 ml of Rhodamine B dye were added to both
the coarse bubble and fine bubble diffuser sides of the lagoon.
The peak concentrations of dye reached the far end of the coarse
bubble side in about 3.5 hours and the effluent at 4 hours. The
relative concentration at the effluent dropped from 28 at 4 hours
to about 7 at 7.5 hours and then began a gradual climb and
leveled off around 22 at 21 hours. The effluent peak at 4 hours
for the coarse bubble lagoon was obviously due to short cir-
cuiting. The gradual increase from the low at 7.5 hours to the
leveling off at 20 hours and greater was due to dye which entered
the aeration pattern. This type of curve is more likely to occur
under complete mix conditions without short circuiting. On this
basis the dye concentration peak for the far end occurred at
about 3 hours due to the high level of mixing in the first cell.
The peak for the effluent did not occur until after 20 hours
because of the low mixing level occurring in the second cell.
A similar action occurred in the fine bubble side of the lagoon.
The dye concentration peaked at 31 at 4.5 hours on the far end
109
-------
Fine Bubble Diffuser side
Wind
<5mpt
Coarse Bubble Diffuser side
Perforated Tubing
Diffusers
\S 2 hrs.
\ Baffle Approx. T
J Below Water Surface
1 ^~i
1 1C
I
L
Bottom Outline
Diffuser Cluster
Figure 23. Visual observation of dye injection in the Ft. Greely lagoon.
-------
35
30 -
25 -
c
o
P 20 -
c
o>
o
c
O
1 10
cr
5 -
Hours
Figure 24. Dye injection results, Ft. Greely coarse bubble aerated lagoon.
-------
35
30
.1 25
0
t-
"c
20
£ 15
_o
CD
10
Cell 1
0
10
15
20
25
Hours
Figure 25. Dye injection results, Ft. Greely fine bubble aerated lagoon,
-------
of the lagoon. Heavy concentrations were visible near the dike
at the far end at less than two hours and a sample taken at this
point read off the scale on the fluorometer. Samples at the far
end of both lagoons were normally taken off the end of the dock.
The curves for the fine bubble side are somewhat more erratic due
to the channeling of the dye around the aeration pattern in the
first cell (Figure 23). It is not known if channeling occurred
in the second cell since the dye became less visible at this
point. The effluent peak occurred around 8.5 hours, which was
about 4 hours later than for the coarse bubble side, and dropped
to around 15 before -climbing back to about 21 at 20 hours.
113
-------
FT. GREELY OXYGEN TRANSFER STUDIES
METHODS AND PROCEDURES
In order to compare the performance of the coarse and fine bubble
aerators, oxygen transfer studies were conducted at the Ft.
Greely lagoon. DO uptake values were determined through the use
of a bottom sludge respirometer constructed at the AERS
laboratory and with light and dark BOD bottle uptake measure-
ments.
Three docks were placed on each half of the lagoon as shown in
Figure 6 to facilitate sampling. DO levels in the lagoon were
determined with a YSI meter (Model 54) and probe (Model 5418).
DO's were measured at various points throughout the lagoon at the
beginning of the sampling season and found to be reasonably
uniform or within approximately 1 mg/1 throughout each half of
the lagoon. Thereafter, DO's were determined at mid-depth from
the three docks on each half of the lagoon and the DO levels
reported are an average of these.
DO uptakes were determined by bringing samples into a laboratory
building and shaking the samples for aeration. The samples were
then placed in BOD bottles in a water bath at the same tempera-
114
-------
ture as the lagoon and the DO's read with the YSI meter
(Model 54) and YSI BOD probe (Model 5420). This procedure was
accomplished within a few minutes. The bottles were agitated and
the DO levels read periodically during the uptake period. Uptake
rates were determined from curves obtained by plotting DO levels
versus time.
Uptake rates obtained during periods of algae growth were deter-
mined by the use of light and dark BOD bottles as described by
Camp (1963). Samples were collected at two depths in the lagoon,
1 foot and 7 foot levels, and placed in four BOD bottles, two of
which were painted black to prevent light penetration. Initial
DO levels were determined in each bottle and these were hung in
the lagoon at the respective sample depths. The bottles were
then removed periodically in alternate pairs and the DO levels
de term ined .
The bottom sludge respirometer consisted of an 8 inch diameter
plastic tube open at the bottom and with a flat cover on the top.
Mounted on the top were a YSI model DO probe and a small sub-
mersible pump supplied by The Little Giant Pump Co., Oklahoma
City, Oklahoma. A large surface area flange was placed around
the bottom to prevent the respirometer from sinking into the
sludge. The bottom of the respirometer was extended 2 inches
with a piece of sheet metal to ensure a good seal at the sludge
face .
115
-------
The submersible pump and probe were mounted so the pump
discharged over the DO probe eliminating any stagnation. The
discharge was restricted so that the flow was very gentle and a
minimum of stirring occurred in the respirometer.
When using the respirometer, a plug was removed from the top and
the respiormeter submerged. All of the trapped air was allowed
to escape and the plug replaced. The unit was then lowered into
place and the submersible pump started. Periodic DO readings
were taken over periods which ranged from 1 to 4 hours.
The true uptake rate of the bottom sludge was determined by sub-
tracting the lagoon liquid uptake rate determined in the BOD
bottles from the rate established in the respirometer .
Values of 0.85 and 0.90 were used for a and g respectively, for
all calculations. These values were obtained through laboratory
tests conducted in a 10-liter cylindrical shaped container.
Lagoon effluent was brought to the laboratory, held overnight,
and two runs made with effluent and two runs with tap water on
the same day, in accordance with the procedure outlined by Ecken
felder and Ford (1970). Gentle aeration was provided with a
glass tube of 3 mm diameter. A value for g was obtained by
aerating the container contents for an extended period and com-
paring the saturation value obtained with the standard value for
the corresponding temperature and pressure. A 6 value of 1.02
was used for temperature correction of the K. a values obtained
116
-------
in these studies. C was calculated for mid-depth in accordance
s r
with methods discussed earlier.
RESULTS
Table 19 presents the oxygen transfer data collected and is
grouped by type of aerator. Also shown is one data point for the
Northway lagoon which at that time had Air Gun aerators. The
last data point is taken from the literature and represents an
evaluation of an Air Gun installation at Brampton, Ontario (Thon,
1964). The data include the effect of surface aeration.
Horsepower requirements were calculated based on the following
formula (Fair et al., 1971):
hp = 0.227 Q ( (P2/P1)°'283 - 1)
Q = Air flow in SCFM (14.7 psia and 70°F)
P- = Discharge pressure of blower (psia)
P, = Atmospheric pressure (psia)
1 hp = 0.746 kW
An overall efficiency loss of 30 percent was assumed for the
blower and motor for all calculations. Actual blower discharge
pressures were used for the Ft. Greely fine bubble and Northway
Air Gun calculations, while 125 percent of the submergence depth,
2
or 0.35 kg/cm was used for the coarse bubble diffusers. This
2
assumes a pressure loss of 0.02 kg/cm through the main header
since the pressure measured at the point of the coarse bubble air
117
-------
Table 19. .Oxygen Transfer Summary
CO
Aerator
Ft. Greely
Coarse
Bubble
Ft. Greely
Fine Bubble
Northway
Air Gun
Brampton
Air Gun
(Thon, 1964)
Date
Feb
Apr
Apr
May
Nov
Dec
Feb
Apr
Apr
May
18
6
28
18
30
22
18
6
28
23
Liquid
Temp
°C
<0.5
<0.5
5.2
10.5
1.0
1.0
<0.5
<0.5
5.2
8.0
14.8
Ice
Cover
%
90
40
0
0
30
70
100
50
0
0
0
D.O.
Level
mg/1
6.9
9.1
5.2
7.0
3.8
0.7
9.1
3.2
1.0
5.0
3.6
D.O.
Uptake
mg/l/hr
0.34
0.23
0.30
0.46
0.42
0.34
0.21
0.17
0.18
0.37
0.43
Air Supply
I/sec -
1000 m3
9.0
12.7
11.7
13.5
12.2
8.7
8.7
4.5
4.3
21.5
17.2
02 Transfe
Efficiency
%
3.8
1.9
2.7
3.7
3.5
4.0
2.5
4.1
4.4
1.7
2.6
;r KLa
' Calcu-
lated
0.064
0.054
0.049
0.142
0.049
0.030
0.047
0.019
0.019
0.070
0.064
(hr-1)
Adjusted
to 20°C
0.094
0.079
0.066
0.170
0.071
0.044
0.069
0.028
0.025
0.088
0.073
kg 02/
KW-hr
0.86
0.44
0.64
0.92
0.82
0.96
0.33
0.65
0.60
0.43
0.44
-------
2
lines tied into the main header was approximately 0.33 kg/cm .
The Brampton A'ir Gun data point was calculated by the author of
that paper using the submergence depth of the aerators, about a
20 percent inherent efficiency loss for compression and a 35 per-
cent efficiency loss for the aeration system (Thon, 1964).
Mixing over the center baffle was too great to permit separate
evaluation of the two types of coarse bubble diffusers at Ft.
Greely. As a result, the diffussr performances have been lumped
together for evaluation. This should not detract substantially
from the results as any difference between the two coarse bubble
aerators will be small compared to that between the coarse bubble
and fine bubble aerators.
The progressive drop in DO levels for the fine bubble diffuser
shown in Table 19 is a result of the clogging mentioned
previously. Data for the fine bubble aerator were not obtained
on May 18 because the lagoon had gone anaerobic at that time-
Oxygen transfer data for November and December were not obtained
because the repunching of the tubing which occurred during the
summer changed the fine bubble diffuser characteristics. The
higher DO uptake values reported for the coarse bubble diffusers
were a result of higher influent flows to that side.
Figure 26 presents a plot of the K. a value at 20°C times the
aeration basin volume per diffuser (K. a x V) versus the air
rate per diffuser (1.0 SCFM = 0.47 liters/sec). The coarse
119
-------
20000
10000
9000
8000
7000
6000
5000
4000
3000
2000
KLa-V
1000
900
800
700
600
500
400
300
200
100
1 1 1 1 1 1 1 1 | 1 1
-
-
: T
-
0
™~ f
T/ T
"~~ ^
s
/ f 1
/ 9
/
1 \ 1 1 1 1
- —
T ~
/'--
/
*
—
/
/ D
— >/^ —
— ^r ~
JT O ~_
— —
— —
_ -
A
— — — Shear f user - From Eckenf elder —
— — — Extension of Eckenf elder Curve
O Ft. Greely Coarse Bubble Diff.
A Ft. Greely Fine Bubble Diff.** _
O Northway Air Gun
D Brampton Air Gun *
A
A * * Values / IOO ft of tubing
\ 1 1 1 1 1 1 1 1 | | I 1 1 1 1
4 5 6 7 8 9 10 20
Gs- SCFM/Diffuser
30 40 50 60 80 100
Figure 26. Air flow rate vs. KLa • V for aerated lagoons.
120
-------
bubble diffusers were evaluated as Shearfusers. This was done
because, situated in the first cell where the oxygen demand was
greatest, the Shearfuser clusters received the major portion of
the total air flow (approximately 80 percent). Each Aer-0-Flo
diffuser cluster was considered as on Shearfuser diffuser (based
on air flow) which made a total of 10 Shearfusers for calculation
purposes.
The solid line shown was obtained from the literature and relates
the K. a value for a certain diffuser and tank configuration to the
tank volume per diffuser (Eckenfelder and O'Connor, 1961). The
curve is based on data obtained in a tank 7.3 m long by 1.2 m
wide by 4.6 m deep, using the Shearfuser diffusers. Other curves
for similar coarse bubble diffusers were shown in the reference
but are not presented here.
Because of the variability of the Shearfuser data obtained at Ft.
Greely, maximum and minimum values of K. a based on possible er-
rors in procedures and equipment were calculated and a range of
K. a values were plotted as shown. The accuracies used in the
calculations were as follows:
C = -0.5 mg/1 - Standard Methods indicates an
accuracy of -0.1; however, -0.5 was used because
of the slow instrument response to the cold
conditions during the studies.
121
-------
r = -15 percent - Sawyer and McCarty (1967) indicates
the BOD test accuracy is considered to be 5 percent.
The 15 percent value was used to account for sampling
error .
3 = -0.05
a = io.10
The uppermost point shown represents the data for May 18 which
is probably the most questionable because of the need to account
for algal DO production and bottom sludge demand. The algal DO
production and bottom sludge demand values were varied by +50
percent and -50 percent respectively for the error calculations.
It should be noted that the somewhat lower efficiencies exhibited
by the Air Gun diffusers on Figure 26 may not be truly represen-
tative. The Northway lagoon had a liguid depth of 2.3 m which
was less than would normally be provided in a lagoon designed for
Air Gun aerators. Also, bottom sludge demand or algae DO produc-
tion was apparently not accounted for in the Brampton study and
may have been significant factors at the liquid temperature
re por ted .
OXYGEN BUDGET
The oxygen uptake rates obtained for the Ft. Greely coarse bubble
lagoon are presented to show the relationship of oxygen demand
at various times of the year to the average BOD loading on the
122
-------
lagoon (Table 20). As may be expected the oxygen demand in-
creased a great deal during the summer months with a good portion
of the increase compensated for by algal production. It appears
from the data presented that a ratio of 1.5 g 0?/g BOD^ removed
can be used for sizing aeration equipment for cold climate
aerated lagoons.
123
-------
Table 20. Ft. Greely Coarse Bubble Lagoon Oxyqen Budget
ro
Date
02/18/72
04/06/72
04/28/72
05/18/72
06/15/721
11/30/72
12/22/72
Mixed Liqour Uptake
kg 02/day
119
83
107
213
446
148
120
Sludge Uptake* Alqae Production Aeration Requirements
kg 02/day kg 02/day kg 02/day
119
83
107
9 59 163
39 155 330
148
120
Ratiot
BOD5 BOD5
Removed Applied
1.5
1.0
1.3
2.0
4.0
1.8
1.5
1.1
0.8
1.0
1.5
3.'
1.4
1.1
Sludge uptake rates found during the winter were less than 2 kg/day and considered negligible.
Ratio = (kg 02/day aeration requirement)/(Average BOD5 applied or removed/day). The average BOD5
applied or removed per day was 106 kg and 82 kg respectively.
The data for 6/1^/72 is considered unreliable because of the very high oxygen transfer rates
found for the aerators. The sludge uptake rate for that date does appear reasonable.
-------
DISCUSSION
BOD AND SS REMOVAL
Year-round BOD percentage removals were plotted in Figure 27 and
curves representing plug flow and complete mix conditions were
applied to the data by least squares methods. The complete mix
curve having the form
E = (A+Kt/1+Kt) 100
where E = Percent BOD removed
A = Initial fraction of BOD removed
K = Reaction rate coefficient (I/day)
appears to most nearly represent the data. 'A' is the fraction
of BOD removed within the first few hours or days through
sedimentation and bio-oxidation. The equation was obtained by
performing a material balance on the lagoon process (Eckenfelder ,
1970) and adding a term for sedimentation. The values obtained:
A=0.56 and K=0.058
are very similar to values reported by Reid (1970) of 0.55 for
the initial removal and 0.063 for the reaction coefficient using
a similar approach.
125
-------
100
CTl
40 60 80
Detention Time (Days) = T
100
Figure 27. Year-round percent BOD removals vs. detention times,
-------
The same equation was applied to the year-round suspended solids
data and values of 0.30 and 0.058 were obtained for A and K
respectively (Figure 28).
These equations were also applied to the winter and summer data
(Figures 29 and 30). 'A1 values were assumed to be constant at
0.56 and 0.30 in order to obtain a comparison of the reaction
rates as follows:
BOD Removal SS Removal
A K A K
Year-round 0.56 0.058 0.30 0.058
Winter 0.56 0.055 0.30 0.048
Summer 0.56 0.066 0.30 0.044
A comparison of the plots for BOD removal and for the remaining
SS shows more scatter in the SS data, particularly for the summer
periods. The EAFB experimental lagoon data has been identified
in these figures to provide a comparison of data from a number
of cells in series with the overall data. In all cases the 6
cell operation provided the best performance; however, much of
this data was obtained during the first 18 months of the lagoon
operation before the aging effect was fully realized. The number
of cells in series seemed to have the most pronounced effect on
summer SS removals when compared to the overall data. This may
be the result of a change in algae species which will be
discussed later. The data also indicates that BOD removals are
127
-------
ro
oo
0
10 20 30 40 50 60 70 80 90 100 110
Detention Time (Days)
Figure 28. Year-round percent suspended solids remaining vs. detention time.
-------
100
90
"S80
70
§60
50
40
80
70
^60
c
"o
I 50
en
on
-1 40
o
CO
"S 30
0>
CO
10
0
EAFB Experimental Aerated Lagoon
A 6 cells in series
o 4 cells in series
• Other Lagoons
0 10 20 30
40 50 60 70 80
Detention Time-days
90 100 110
Figure 29. Winter percent BOD removal and percent suspended solids remaining
vs. detention time.
129
-------
100
80
"g
"o
I
I40
~o
CO
CD
£20
CL
to
CO
0
I
I
I
I
0
20
40 60 80
Detention Time-days
100
120
Figure 30. Summer percent BOD removals and percent suspended solids remaining
vs. detention time.
130
-------
improved in the summer although the SS remaining is increased and
much more variable because of algae growth.
SOLUBLE BOD REMOVAL
A small fraction of BOD residual does not appear to be removed,
even after long detention periods (Eckenfelder and O'Connor,
1961). This has been attributed to an equilibrium between BOD
removed and the release back to solution of respiration and auto-
oxidation end products. A plot of soluble (filtered through
45 micron filter paper) BOD values shows this residual to be
about 10 mg/liter for aerated lagoons with detention times less
than 40 days (Figure 31). Reduction of the soluble BOD to
10 mg/liters can occur within 20 days detention time even under
extreme winter conditions. After this time, removals of BOD oc-
cur through auto-oxidation and sedimentation of solids.
Soluble BOD data was obtained from the EAFB Experimental Lagoon
and the Ft. Greely Lagoon under winter conditions and from the
Ft. Greely Lagoon under summer conditions. Soluble BOD informa-
tion was also obtained from a report by Girling et al . , (1973)
on four aeration basins operated in series. The values shown at
zero detention time represent the influent to the lagoon. In the
case of the Winnepeg lagoons, the raw waste was fed to a primary
cell where the soluble BOD increased before entering the aerated
cells.
131
-------
120
100
80
CD
jl
a 60
o
CD
~o
C/)
40
20
0
o Winnepeg Aerated Lagoons
A EAFB Experimental Lagoon
Ft, Greely Aerated Lagoon
0
10 20
Detention Time (Days)
30
40
Figure 31. Soluble BOD vs. detention time.
132
-------
REACTION RATES
Reaction rates are dependent on substrate concentrations and, in
lagoon systems, will consequently be dependent on detention
times. For a single cell lagoon, increasing the detention time
will decrease the overall reaction rate because of the increased
substrate dilution. Increases in lagoon detention times result
in lesser increases in BOD removal efficiencies (Thirumur-
thi, 1974). This is an important consideration in determining
the removal efficiencies of lagoon cells operated in series using
the relationship 1/(1+KT) since the value of K will decrease
with each succeeding cell in series.
After initial oxidation occurs in a biological waste treatment
process, the cellular constituents are progressively more dif-
ficult to oxidize and the rate declines in a logarithmic manner
(Eckenfelder and O'Connor, 1961).
The year-round BOD and SS removal rate coefficients (K) were
determined for each cell of the lagoons under consideration and
plotted vs loading on log-log paper (Figures 32 and 33). The
curves were determined by least squares method. Figures 34
through 37 show plots of winter and summer BOD and 55 removal
rate coefficients.
A slight curve in the data, particularly for the summer data, ap-
pears to exist in the log-log plot. The smaller summer K values
133
-------
GO
-p.
g 0.005
^ 0.003
0.002
0.001
0.1 0.2 ,0.4 1.0 2.0 4.0 10 20 40 100
Loading (g BOD/1000m-day)
400
Figure 32. Overall BOD removal rate coefficient vs. loading.
-------
CO
en
1.0
0.6
0.4
0.2
i
-£ 0.1
a;
« 0.06
o
o
o
cr
0.04
0.02
0.01
0.005
OO03
0.002
0.001
i—i—i i i i 1
Correl. Coef. i
0.79
= 0.018La72 0.73
Negative k values
not used
I i I I I I I I I ,1 I I I I I I I I I I I fS\ I I II I 7g> I I
0.1 0.2 0.4 1.0 2.0 4.0 10 20 40 100
Loading (g BOD/1000m-day)
Figure 33. Overall suspended solids removal rate coefficient vs. loading.
400
-------
CO
1.0
0.6
0.4
0.2
0.1
-------
GO
= 0.014 LQ83
k = 0.011 L°'94
1 0.2 0.4 1.0 2.0 4.0 10 20 40 100 400
Loading (g BOD/1000m-day)
Figure 35. Summer BOD removal rate coefficient vs. loading.
-------
GO
00
1.0
0.6
0.4
0.2
*:
i
^ 0.1
0>
£ 0.06
« 0.04
o
o
£ 0.02
o
cr
rr
0.003
0.002
k = 0.034L0-44
k= 0.(
Correl. Coef. 1
0.53
0.59
Negative k values
not used
0.001
0.1
i i i i i i l i
i i fl^ i i i
0.2« 0.4 1.0 2.0 4.0 10 20 40 100 400
Loading (g BOD/1000m3-day)
Figure 36. Winter suspended solids removal rate coefficient vs. loading.
-------
OJ
1.0 r
0.5
0.3
0.2
*:
I 0.1
g .05
•*—
s* \
.03
.02
o
O
cr
c
o
.01
o .005
a>
.002
.001
i ~\ i i i i i I 1 1—i—i I i i 1
. * *
k = 0.0141_°-63
k = 0.009 Lv
0.88
Correl. Coef.
0.59
0.60
0.1 0.2 0.4 1.0 2.0 4.0 10 20 40 100
Loading (g BOD/1000m -day)
400
Figure 37. Summer suspended solids removal rate coefficient vs. loading.
-------
at the lower loadings are assumed to be caused by algal growth.
The apparent non-linear relationship has been accounted for by
fitting two curves for each set of data points, one for lower
loadings and one for higher loadings. Some of the data points
were not used in determining the curves. These points are in-
dicated on the figures. The curves indicate a relatively rapid
increase in removal rates with increasing loading at the lower
loadings. This condition makes it more difficult to apply the
data to lagoons at the lower loadings, as will be seen in the
sample calculations section.
SLUDGE ACCUMULATION
The need for adequate sludge storage in aerated lagoons is made
particularly clear by the Eagle River Lagoon experience where ef
fluent quality deterioration was obviously caused by sludge car-
ryover. Lower aerated lagoon performances after the first year
of operation are also apparently caused by sludge accumulation.
These factors point out the need for incorporating sludge ac-
cumulations into aerated lagoon designs.
Following are average sludge analyses for the Northway and Ft.
Greely lagoons:
140
-------
Total
% Solids % Volatiles pH COD(mg/g)
Northway
Cell 1 12 50 7.1 88
Cell 2 20 29 7.6 46
Ft. Greely
Cell 1 21 42 5.9
Cell 2 52 7
The Northway sludge exhibited the characteristics of well
digested sludge. The pH was relatively high and the sludge had
a black appearance and a musty odor. These conditions indicate
significant methane fermentation and loss in the form of methane
of relatively large amounts of oxygen demand from the system. On
the other hand, the Ft. Greely sludge exhibited a low pH and
brown, odorous characteristics which indicate production of
volatile acids which were not transformed to methane but diffused
into the liquid and exerted an oxygen demand. The Ft. Greely
sludge pH levels were lower than those reported by Oswald (1968)
as optimum for methane formation but near optimum for organic
acid formation. pH levels for the Northway sludge were generally
in the optimum range for methane formation. It is possible that
the poor sludge digestion of the Ft. Greely lagoon occurred
because the solids were deposited immediately upon entering the
lagoon, probably in a septic condition, so that optimum condi-
141
-------
tions for organic acid formation were present and perpetuated
from the beginning. The lagoon began operation in late fall when
the low temperatures would also preclude the growth of methane
formers. Oswald (1960) has stated that lagoon bottom sludge can
exhibit characteristics of a stuck digester (i.e., high pH which
retards methane fermentation) and that overcoming this condition
is quite difficult. It follows that startup of lagoons should
occur during the warmer summer months or sludge seed containing
methane formers, such as from a sludge digester, should be added.
Also, if the entering solids are maintained in suspension for a
period, undergo some degree of aerobic oxidation and are
deposited under the higher pH conditions existing in the lagoon
mixed liquor, conditions more conducive to methane formation may
be maintained.
The sludge analyses for the Ft. Greely and Northway lagoons are
somewhat variable but indicate that decomposition of the sludge
occurs year around. Rubel and Gray (1965) also reported
% Volatiles of approximately 50 for sludge samples taken in
January and February and Duly and September. This is in agree-
ment with values reported by other investigators.
Very little information is available on rates of sludge accumula-
tion. Sludge volumes obtained from the Northway and Ft. Greely
lagoons and information reported by Penman et al., (1970) are
shown in Table 21.
142
-------
Table 21. Sludge Accumulation Summary (8,/lDOO m )
Cell 1 Cell 2 Total
Northway 935 465 1400
Ft. Greely 620 145 765
Winnepeg
Air Aqua 1720 380 2100
Air Gun 1880 1880
At Winnepeg the high volumes of sludge may be explained by the
fact that the information was obtained during the first eighteen
months of operation. The Northway and Ft. Greely lagoons were
somewhat older when conditions closer to equilibrium existed.
This follows from Fair's estimate that it takes over five years
to stabilize stream sludge deposits. Using Northway as the most
typical situation, it is suggested that for sludge accumulation
calculations a value of 1500 liters/1000 m of domestic sewage
be used .
143
-------
ALGAE
The major algae blooms in subarctic lagoons occur around the
month of June and are reduced significantly after the sludge
turnover, which generally occurred in early July in the lagoons
observed. This is illustrated by the Ft. Greely lagoon ex-
perience. Major algae growth appears to begin after approx-
imately ten days detention time and follows a typical growth
curve as shown by the EAFB experimental aerated lagoon ex-
perience .
The 1971 experience with the EAFB experimental aerated lagoon
generally agree with statements by Gloyna (1968). Chlorella were
dominant during the major algae bloom of June and early July when
high sludge decomposition rates and the growth of high energy or-
ganisms resulted in presumably high loading. After the sludge
turnover and the corresponding reduction in the lagoon loading,
Daphnia and filamentous algae became dominant with reduced levels
of unicellular organisms resulting in reduced effluent SS levels.
A suitable environment for zooplankton growth, as suggested by
Dinges (1975), was apparently present.
The correlation of loading and algae blooms is also born out by
the Palmer lagoon experience. Summer loading on the total lagoon
was 2 g BOD/m -day with resultant BOD and SS levels of 6 and
18 mg/liter respectively. Assuming a 55% removal in the aerated
cell as for July through September, 1973, the loading on the
3 ?
facultative pond was 1.7 g BOD/m -day or 5.1 g BOD/m -day.
144
-------
The advantage of operation with a number of cells in series is
illustrated by a comparison of the EAFB experimental lagoon and
Ft. Greely lagoon data. The peak chlorophyll values and cor-
responding SS values obtained were as follows:
Chlorophyll (m-
EAFB Experimental Lagoon 780 86
Ft. Greely Lagoon 1100 141
The higher Ft. Greely values are attributed to the lower number
of cells in series. A greater diffusion of incoming raw waste
occurred because of the complete mix conditions and the high
degree of short-circuiting in that lagoon. The result is a
higher level of bacterial activity throughout the lagoon and a
correspondingly greater algae growth apparently because of the
carbon dioxide generated.
NUTRIENTS
The nutrient data results indicate little change in NH-.-N or T-N
levels during winter operations and removals of N H -, - N ranging
from 25 to 48% in the summer. T-N removals were less, indicating
a transformation of inorganic Nitrogen to the organic form by al-
gae .
Ortho-phosphates and total phosphorus levels increased in almost
all cases which would indicate the net annual removals to be
145
-------
zero, assuming the analytical results were accurate. The
phosphorus apparently had previously accumulated in the bottom
sludge and was being released to the lagoon liquid.
These results are apparently typical of lagoons operated under
cold climate conditions.
COLIFORMS
The coliform removal data from the EAFB experimental lagoon and
the Harvey, N. Dakota lagoon followed expected patterns (Figure
38). Die off rates were greater during summer periods. Also,
for a given detention period, the more cells in series the
greater the die off rate. The latter experience is in agreement
with results reported by other investigators (Slanetz et al . ,
1970). The EAFB experimental lagoon achieved 99.98% removal
during winter operation with 6 cells in series and during summer
operation with 4 cells in series.
The effectiveness of disinfection chambers at the EAFB full scale
lagoon and the Eagle River lagoon are shown in Figure 39. At-
tempts to correlate coliform counts with the product of contact
time and chlorine residual were not successful and better results
were obtained plotting coliform levels vs contact time. The data
from the Eagle River and EAFB lagoons indicate little difference
in disinfection effectiveness during winter and summer opera-
tions. This would seem to indicate the summer algae production
146
-------
100
o100
o
£
-------
200
1 A
50
o
o
-------
results in disinfection rates similar to those during cold tem-
perature operations in winter.
The fecal coliform data also supports the contention that
monitoring chlorine residual as a means of determining disinfec-
tion effectiveness will not be satisfactory. The EAFB lagoon ef-
fluent coliforms were reduced at lower contact times and lower
chlorine residuals than the Eagle River Lagoon effluent
coliforms .
AERATION SYSTEMS
Although fine bubble diffusers have performed successfully in
aerated lagoons for a number of years, clogging is obviously an
inherent characteristic in their operation. The clogging can
cause maintenance problems, particularly in small installations
where the operator may have many other duties to attend to aside
from operation of the waste treatment system. Some problems
which have occurred include blower damage, breaks in plastic
piping, blowing out of the ceramic diffusers, etc. Many problems
have also occurred with the plastic pipe in the Eagle River
lagoon which were not associated with high system pressure.
In most cases, cleaning of fine bubble diffusers is required with
greater frequency than recommended by the manufacturer. Per-
forated tubing cleaning is generally required monthly to maintain
desired blower discharge pressures. Cleaning of the porous
149
-------
ceramic diffusers may be required once per year, based on the
limited information available.
Obstruction of the fine bubble aerators may occur internally
during shutdown of the blowers which allows wastewater and
suspended matter to enter the aeration system through the dif-
fusers and leaks in the piping. Clogging can occur through ob-
struction by particulate matter or through an inability to force
water out of the system through the diffusers. Removal of the
material from the tubing may be accomplished by installation of
bleed lines and "rocking" the system as at the Palmer Lagoon.
Particulate matter in the air supply will also cause internal
clogging although this has not been a problem at most sites in
Alaska .
External restrictions can be caused by calcium carbonate deposits
from hard water or organic slime growths over the diffusers.
Clogging of the perforated tubing, which is designed to lie on
the lagoon bottom, may also* occur from sludge deposits on top of
the tubing. Clogging of the porous ceramic diffusers can occur
during blower shutdowns due to lint and hair collecting on the
diffusers and in the pores.
Routine cleaning of both types of fine bubble diffusers is
generally accomplished with hydrochloric acid fed to the aeration
system and forced through the diffusers at approximately
2
1.4 kg/cm or by applying hydrogen chloride gas to the system
150
-------
while the blowers are in operation. The latter method requires
the greatest care because of the toxic and corrosive nature of
the material. Amounts of material used for cleaning have varied
considerably. In the case of perforated tubing, quantities of
3.7 and 1.6 g/m of hydrochloric acid and hydrogen chloride gas,
respectively, appear to be adequate if a monthly cleaning
schedule is adhered to. Sufficient information was not available
on the porous diffusers to determine the amount of cleaning
material required.
In a number of cases, more extreme cleaning methods have been
necessary. These have included draining the lagoon to a level
which would permit access to the diffusers and hand cleaning with
the blowers in operation.
Air Gun aerators have also been utilized in lagoons for a number
of years. The main operating problem has been blocking by rags,
and whether this problem has been corrected is not known.
AERATION DIFFUSERS
Information has been presented which indicates the coarse bubble
diffusers can provide an attractive alternative for aeration in
lagoons, particularly in smaller systems. The K.a values ob-
tained from the Ft. Greely coarse bubble diffuser studies cor-
relate well with those obtained for the same diffuser in a large
scale activated sludge aeration tank model. The data shows that
151
-------
coarse bubble aeration systems for lagoons can be designed based
on oxygenation efficiencies published in the literature or sup-
plied by diffuser manufacturers. The oxygenation efficiencies
should be obtained from large scale test tanks rather than small
columns, however, for reasonable accuracy. The data also in-
dicates the K. a value can be predicted for coarse bubble dif-
fusers in lagoons using the equation developed by Eckenfelder and
information presented in the literature (Eckenfelder and
O'Connor, 1961; Eckenfelder and Ford, 1968).
Studies have shown that increased aeration tank widths decrease
oxygenation efficiencies to a certain minimum level but that
spreading the diffusers out over the tank bottom increases oxy-
genation efficiencies. The large width to depth ratio of lagoons
will decrease diffuser efficiencies to some extent, probably 2
to 3 percent efficiency for coarse bubble diffusers based on
studies mentioned previously (Bewtra and Nicholas, 1964). Ef-
ficiencies for a given diffuser can be maximized, however, by
adequate spacing to minimize interfering bubble patterns.
Although the fine bubble diffusers1 oxygenation efficiencies are
greater, the diffusers are not necessarily more economical. The
data presented in Table 19 indicates approximately 0.79-0.84 kg
transferred/kWh for the coarse bubble diffusers, as opposed to
approximately 0.6 kg 0 transferred/kWh for the fine bubble dif-
fusers under generally clogged conditions. Assuming for the Ft.
152
-------
Greely lagoon that 190 1/s at 0.35 kg/sq cm would be required for
a coarse bubble diffuser system while 142 1/s at an average of
0.46 kg/sq cm would be required for a fine bubble diffuser system
under normal conditions, the increased cost for the coarse bubble
system would be $78/year greater at 2 cents/kWh. However, if
cleaning were required monthly for the fine bubble diffus-ers, as-
suming 4 man hours per cleaning at $10/hour and $8 material cost,
maintenance cost would be $576/year or a net $498/year greater
cost for the fine bubble diffuser system. These differences will
increase if hand cleaning is necessary and decrease if higher
power costs exist. Based on the above, it appears that operation
and maintenance costs for fine bubble diffusers may be equal to
or greater than the costs for coarse bubble diffusers if sig-
nificant clogging occurs.
One aspect of aeration system design which must be considered in
some areas is ice fog generation. Visual observations at Ft.
Greely indicated open water over all four coarse bubble diffuser
clusters throughout the winter period. These open areas
decreased in size as the air temperature decreased and would al-
most completely ice over above the Aer-0-Flo clusters at -40°C.
The open area above the Shearfuser cluster near the influent al-
ways remained larger, shrinking to about 7.5 m in diameter at
-40°C. Significant ice fog generation seemed to occur only over
this cluster. Ice fog blankets were not observed around the
lagoon as the ice fog formed was either not enough to become a
153
-------
nuisance or dissipated rapidly. It should be noted that the in-
fluent sewage temperatures to this lagoon range around 20°C even
in winter and that lower influent temperatures would reduce ice
fog generation. During the colder period of the year, the per-
forated tubing side of the lagoon was completely ice covered and
no ice fog was observed.
Although no attempts at heat balance calculations have been made,
an observation is that greater heat losses occur over diffusers
with larger air flows or greater turbulence because of the larger
open areas maintained. This greater heat loss through the open
area is compensated for by increased ice thickness, or lesser
heat losses, through the rest of the lagoon. Thus, a fine bubble
diffuser lagoon may have a thin ice cover over the total surface
while a coarse bubble lagoon may have thicker ice over less than
100 percent of the lagoon due to greater concentration of air
flows. Where ice fog may be a problem or extensive freezing is
anticipated, diffusers should be selected which require less air
flow per diffuser and will permit greater dispersion of the air
pattern. Smaller clusters of diffusers should also be used. As
indicated previously, oxygenation efficiencies will not be sig-
nificantly affected as transfer rates are independent of diffuser
spacing .
154
-------
LAGOON DESIGN AND UPGRADING
DISCUSSION
A comparison of data from the Eagle River and Palmer lagoons il-
lustrates the importance of proper design. Second year overall
series operation data from the Eagle River lagoon and data for
the period May 1, 1974 through April 30, 1975 for the Palmer
lagoon were plotted on probability paper. The percentage of BOD
and 55 analyses that exceeded 30 mg/1 and 70 mg/1 were as fol-
lows:
Loading
Lagoon 3j3 m_g_ BOD 3>TJ m_g_ S_S 7_0 m_g_ S_S c[ BOD/m--day
Eagle R. 55 70 30 10.2
Palmer 10 4 <1 1.7
The Eagle River lagoon performance, although poor, is the more
typical of present subarctic lagoons. The lagoon is overloaded,
has inadequate sludge storage and has been plagued with aeration
system problems which have contributed to the poor performance
results. The Palmer lagoon, on the other hand, while not an
ideal design, has a considerable reserve capacity. Some problems
have been encountered with the fine bubble aeration system.
155
-------
These problems have been minimized by close attention to the
lagoon and some innovative maintenance provisions such as instal-
lation of bleed off piping at the ends of the main air headers
to blow water out of the tubing diffusers.
In the design or upgrading of cold climate lagoon systems, the
following objectives should be kept in mind:
1. As in any biological treatment system, conversion of dis-
solved and colloidal organic material into suspended solids which
can be removed by sedimentation is essential. Soluble BOD can
be reduced to around 10 mg/1 in relatively short periods
(<20 days) even at 0°C liquid temperatures.
2 . A high proportion (25-50 ?o) of the first cell aeration should
be concentrated at the lagoon influent to prevent buildup of
sludge under septic conditions.
3. Adequate sludge storage must be provided in the first sec-
tions of the lagoon so thaf adequate treatment of the organic
acids etc., given off during summer fermentation, occurs before
the effluent is discharged. Accumulation of approximately 1500
liters of sludge per 1000 m of influent should be allowed for.
4. Lagoon cells should be provided in series to rsducs short-
circuiting due to complete mix conditions and other causes. For
lagoons of a given detention time, the numbers of bacteria and
indicator organisms are reduced further in multicell series
systems than in single cell lagoons.
156
-------
5. A polishing or maturation pond should be provided as the last
cell in series to allow sedimentation of any settleable solids
and consumption of unicellular algae by higher organisms. Care
should be taken to provide an optimum environment for zooplankton
growth. Loading on the polishing pond should be limited to 1 -
1.5 g BOD/m3-day or 4 - 5 g BOD/m2-day.
A suggested lagoon arrangement is shown in Figure 40 and sample
design calculations follow. A short detention cell is created
at the influent structure by constructing a baffle. Heavy aera-
tion in this cell will keep more solids in suspension and allow
greater aerobic oxidation before the solids are deposited. Also,
the soluble BOD will undergo greater reduction with higher VSS
levels .
Sludge storage is provided over the total bottom area of the
aerated cells in order to avoid excessively deep sludge deposits.
Colder sludge temperatures can be expected with deeper deposits
which will result in reduced decomposition rates. The aerators
are shown elevated and also in a configuration which will allow
sludge removal.
Placing of the aerators in a straight line parallel to the flow
and along the full width of the lagoon will also aid in reducing
short-circuiting. A rolling motion of the fluid will be
established in the section between each line of aerators which
will promote mixing of incoming waste in that section before the
157
-------
Baffle-
Diffuser
Cell 1
9'-12'Typical
o
Cell 2
V
Cell 3
6 i7
V
Cell 4
Rubble
Figure 40. Suggested lagoon arrangement.
158
-------
waste moves to the next section. The aeration pattern will tend
to create a barrier to complete mixing throughout the pond and
thereby reduce short-circuiting. Short-circuiting can be further
reduced by the strategic placement of baffles which, do not extend
to the pond surface but which serve as an additional barrier to
complete mix conditions.
A polishing pond is provided to permit sedimentation of any
remaining settleable solids during winter operation and to
provide for algae reduction during summer operation. The pond
should provide a suitable environment for macro-organisms such
as Daphn ia which prey on the algae. If aeration is provided it
must be gentle and not promote excessive agitation. Adeguate
dilution must be provided to reduce organic concentrations and
to curb algae blooms which raise pH. Rubble may be included in
order to provide a surface for the growth of the macro-organisms.
Some precautions regarding freezing must be considered when using
a lagoon arrangement as suggested in Figure 40. In the design
of multi-cell systems, special care must be taken to avoid
freezing problems when transferring from one cell to another.
The application of adeguate insulation and/or the addition of
heat (heat tapes e.g.) at the transfer points are necessary in
Arctic and Subarctic areas (Lynn Wallace, personal communication,
1976). Also, if the baffles are designed to extend into the
freezing zone, special baffle designs must be provided to prevent
ice damage.
159
-------
Possible alternatives to the above scheme include long term
storage with discharge once or twice per year at appropriate
receiving water conditions (Pierce, 1974); phase isolation as
practiced in California (Hiatt, 1975); and discharge to natural
lakes or swampland as described by Grainge et al., (1972).
All of the above considerations should be examined in the design
of new lagoons or upgraded lagoons.
SAMPLE CALCULATIONS
It has been shown that the reaction coefficient in the complete
mix equation is related to loading by the following equation (See
Figures 32 and 33):
(1) K = aLb
where K = reaction coefficient
L = loading (g BOD/m3-day)
a&b = constants
Also :
(2) L = S /t
o
where SQ = influent BOD (mg/1)
t = detention time (days)
By substitution into the complete mix equation it can be shown
that :
160
-------
3)
t =
a . S
Using Figures 32 through 37 and the above relationships, the per
formance of a lagoon may be predicted.
As an example, winter BOD removals have been predicted for a
lagoon as follows:
Assumptions :
S (Influent BOD) = 250 mg/1
o
S (Effluent BOD) = 20 mg/1
e ^
55 (Influent Suspended Solids) = 200 mg/1
55 (Effluent Suspended Solids) = 20 mg/1 (winter)
55 (Effluent Suspended Solids) = 60 mg/1 (summer)
Cell 1 DT
Cell 2 DT
Cell 3 DT
Cell 4 DT
Cell 1
10 days
15 days
15 days
v
L = S /T = 250/10 = 25
o
From Figure 34, K = 0.15
5=5 /(I + Kt) = 250/(1 + 0.15 X 10) = 100 mg/1
e o
161
-------
Cell 2
L = 100/15 = 6.7
From Figure 34, K = 0.08
S = 100/(1 + 0.08 X 15) = 45.5 mg/1
e
Cell 2
L = 45.5/15 = 3.0
From Figure 34, K = 0.056
S = 45.5/(l + 0.056 X 15)
e
Cell 4
Using equation (3)
t =
= 24.7
24.7/20 - 1
,0.49
l/U-0.49)
0.033 X 24.7
1.96
t = (0.24/0.16)
t = 2 . 2 days
Total detention time required = 42 days. Using the same approach
for summer BOD removals, the performance would be as follows:
Cell 1_
L = 250/10 = 25
From Figure 35, K = .20
S = 250/(1 + 0.20 X 10) = 83.3
162
-------
Cell 2
L = 83-3/15 = 5.6
From Figure 35, K = 0.056
S = 83-37(1 + 0.056 X 15) = 45.3
Cell
L = 45.3/15 = 3.0
From Figure 35, K = 0.030
S = 45.3/(l + 0.030 X 15)
= 31.2
Cell 4
Using Equation (3
31.2/20 -1
t =
0.94
0.011 X 31.2
(0.56/0.28)16'7
= unrealistically high
Because of the rapid decline of the K values at low loadings, the
last cell size is unrealistically high. Try 5 cells in series:
Cells 1-4 DT = 10 days
Cell !_
L = 250/10 = 25
K = 0.20
S =83.3
e
Cell 2
L = 83.3/10 = 8.3
163
-------
K = 0.08
S = 83.3/U + 0-08 X 10) = 46.3
e
Cell 3_
L = 46/10 = 4.6
K = 0.046
S = 46/(l + 0.05 X 10) = 31.5
e
Cell 4
L = 31.5/10 =3.2
K = 0.033
S = 31.5/Cl + 0.033 X 10)
e
= 23.7
Cell 5
Using Equation (3 )
23.7/20 - 1
t =
0.94
0.011 X 23.7
(.018/0.22)16'7 =0.05
Again, because of the rapid decline in K values at lower
loadings, the last cell size obtained with equation (3) is not
realistic. The calculations do indicate that 5 cells total with
•
the first 4 cells sized at 10 days detention time each will be
adequate. The last cell should be sized using the loading factor
of 1.5g BOD/m -day-
164
-------
t = SQ/1.5 r 23.7/1.5 = 16 days
Total detention time = 56 days
Using the 5 cells in series, the winter BOD removals would be as
follows using Figure 34:
Cell 1_
L = 250/10 = 25
From Figure 34, K = 0.15
S = 250/U + 0.15 X 10) = 100
cJ
Cell 2
L = 100/10 = 10
K = 0.10
S = 100/(1 + 0. 10 X 10) = 50
e
Cell 3_
L = 50/10 = 5
K = 0.07
S r 50/(1 + 0.07 X 10) = 29.4
e
Cell _4
L = 29.4/10 = 2.9 '
K = 0.055
S = 29.4/U + 0.055 X 10) = 19.0
165
-------
Cell 5_
L = 19.0/16 =1.2
K = 0.036
5 = 19.0/(1 + 0.036 X 16) = 12
e
Summer suspended solids removals are estimated as follows using
Figure 37 :
Cell 1
L = 200/10 = 20
K = 0.095
S = 200/(1 + 0.095 X 10) = 102.6
e
Cell 2
L = 102.6/10 =10.3
K = 0.063
S = 102.6/U + 0.063 X 10) = 62.9
C
Cell 2.
L = 62.9/10 =r 6.3
K = 0.046
S = 62.9/(l + 0.046 X 10) = 43.1
tJ
Cell 4.
L = 43.1/10 = 4.3
K = 0.033
S = 43.1/Cl + 0.033 X 10) = 32.4
166
-------
Cell 5_
L = 3.2
K = 0.025
5 = 32.4/(l + 0.025 X 16) = 23.14
Winter suspended solids removals using Figure 36 would be as fol
lows :
Cell 1
L = 200/10 = 20
K = 0.12
Sp r 200/(1 + 0.12 X 10) = 90.9
Cell _2
L = 90,9/10 = 9.1
K - 0*065
S = 90.9/(1 + 0.065 X 10) = 55.1
e
Cell ^
L = 55. 1/10 = 5.5
K = 0.044
S r 55.1/Cl + 0.044 X 10) = 38.3
e
Cell 4
L = 38.3/10 = 3.8
K = 0.032
167
-------
Cell
S = 38 .3/(l + 0.032 X 10) = 29.0
e
L = 29.0/16 = 1.8
K = 0.018
S = 29.0/(1 + 0.018 X 16) = 22.5
e
Since the effluent suspended solids are above 20 mg/1, use equa-
tion (3) to recalculate the cell 5 detention time requirement.
Using equation (3)
t =
29.0/20 - 1
0.78
0.012 X 29.0
4.55
t = (0.45/0.17)
= 83.9 days
Again, the detention time for cell 5 is unrealistical1y high. In
order to obtain winter suspended solids levels of 20 mg/1 or
*
less, an additional short detention time cell should be added or
the size of some of the first four cells should be increased.
The advantage of using a number of cells in series is shown in
Figure 41. The winter BOD removal efficiency of the 5 cell
lagoon derived above is compared to the BOD removal efficiency
of a 3 cell lagoon determined in the same manner. The 5 cell
lagoon with shorter detention times in the first cells obviously
168
-------
100
90
80
O
I 70
Q
O
CO
60
O
i_
o>
Q_
50
10
Cells in series
20 30 40 50
Detention Time (Days)
60 70
Figure 41. Effect of cells in series on detention time.
169
-------
will result in more efficient treatment. A lagoon designed by
the procedures outlined above can be expected to meet
30 mg/1 BOD5 and 30 mg/1 SS standards in the effluent over 90%
of the time. This conclusion is based in part on the performance
of the Palmer lagoon (see Figure 22).
The use of a very short detention time per cell (one day for ex-
ample) will result in higher loadings and correspondingly higher
removals when predicting performance from Figures 32 through 37.
This approach is not recommended, however. Unrealistically high
removal predictions may be the result.
170
-------
REFERENCES
Barsom, George. Lagoon Performance and the State of Lagoon Tech-
nology. EPA-R2-73-144. Prepared for Office of Research and
Monitoring. U. S. Environmental Protection Agency, Washing-
ton , D.C. , 1973.
Bewtra, Jacinder K., and William R. Nicholas. Oxygenation from
Diffused Air in Aeration Tanks. Journal of the Water Pollu-
tion Control Federation, 36, 1195, 1964.
Benjes, H. , Dr. Field Evaluation of Aeration Equipment. In:
Transactions 19th Annual Conference on Sanitary Engineering,
Bulletin No. 60, The University of Kansas, Lawrence, Kan-
sas , 1969 . p . 27.
Breimhurst, Lawrence H. Minnesota Aerated Pond Study for the
Minnesota Pollution Control Agency- By: SERCO
Laboratories, Minneapolis, Minnesota, August 28, 1970.
Camp, Thomas R. Water and Its Impurities. Reinhold Book Cor-
poration. New York, 1963. pp. 306-307.
Champlin, Robert L. Supplemental Aeration of Lagoons in Rigorous
Climatic Areas. Project No. 17050 DVO. U.S. Environmental
Protection Agency, October 1971.
Christianson, C. D., and D. W. Smith. Diffusion Systems for Cold
Climate Aerated Lagoons. In: International Symposium on
Wastewater Treatment in Cold Climates. University of
Saskatchewan, Saskatoon, Canada, 1973.
Clark, S. E., H. 3. Coutts and R. Jackson. Alaska Sewage
Lagoons. Second International Symposium for Waste Treatment
Lagoons, Kansas City, Missouri 1970.
Conway, R. A., and G. W. Kumke . Field Techniques for Evaluating
Aerators. Journal Sanitary Engineering Division, ASCE, 92,
21, 1966.
Dinges, R. 'Wee Beasties' May Improve your Effluent. Water and
Wastes Engineering, March 1975.
171
-------
Dutton, C. S., and C. P. Fisher. The Use of Aero-Hydraulic Guns
in the Biological Treatment of Organic Wastes. Proceedings
21st Industrial Waste Conference. Purdue University, 1966.
p. 403.
Eckenfelder, W. Wesley, Jr. Absorption of Oxygen from Air
Bubbles in Water. Proceedings ASCE, Journal of the Sanitary
Engineering Division, 85, 2090. 1959.
Eckenfelder, W. W., Or.. Water Quality Engineering for Prac-
ticing Engineers. Barnes and Noble, New York, 1970. p 163.
Eckenfelder, W- W., Jr., and Davis L. Ford. New Concepts in 0^
Transfer and Aeration. Advances in Water Quality Improve-
ment. University of Texas Press. Austin, 1968. p. 215.
Eckenfelder, W. W., Jr., and D. L. Ford. Water Pollution Control
- Experimental Procedures for Process Design. The Pemberton
Press, New York, 1970. pp. 103-112.
Eckenfelder, W. W., Jr. and A. J. England, Jr. Temperature Ef-
fects on Biological Waste Treatment Processes. In: Inter-
national Symposium Water Pollution Control in Cold Climates,
R. S. Murphy and D. Nyquist, eds. University of Alaska,
1970. pp. 180-190.
Eckenfelder,* W. W., Jr. and D. J. O'Connor. Biological Waste
Treatment. Pergamon, Oxford, 1961. p. 58, 100-116.
Fair, Gordon Maskew, John Charles Geyer, and Daniel Alexander
Okun . Elements of Water Supply and Disposal. John Wiley
and Sons, Inc., New York, 1971. p. 582.
Federal Register, Vol. 42 (195), Friday, Oct. 7, 1977, pp 54664
- 54666.
Foree, G. F. and C. P. Wade. Factors Regulating the Growth of
Algae in Continuous Culture in Diluted Secondary Sewage
Treatment Plant Effluent and Subsequent Biodegradability.
Research Report NO. 45, University of Kentucky, Water
Resources Institute, Lexington, Kentucky, 1972.
Girling, R. M., A. R. Pick, and A. J. England, Jr. Further Field
Investigation on Aerated Lagoons in the City of Winnipeg.
In: International Symposium on Waste Treatment in Cold
Climates. University of Saskatchewan, Saskatoon, Canada,
1973. pp. 99-124.
172
-------
Gloyna, E. F. Basis for Waste Stabilization Pond Designs. In:
Advances in Water Quality Improvements, E. F. Gloyna and
W. W. Eckenfelder, 3 r . , e d s . University of Texas Press,
Austin and London, 1968. pp. 397-408.
Gloyna, E. F. and 3. Aguirre. New Experimental Pond Data. In:
Second International Symposium for Waste Treatment Lagoons,
R. E. McKinney, ed. University of Kansas, Lawrence, Kansas,
1970 .
Gordon, R. C. Winter Survival of Fecal Indicator Bacteria in a
Subarctic Alaskan River. Publication No. EPA-R2-72-013 , En-
vironmental Protection Agency, Arctic Environmental Research
Station, College, Alaska, 1972. 41 pp.
Gordon, R. C., C. V. Davenport and B. H. Reid. Chlorine Disin-
fection of Treated Wastewater in a Baffled Contact Chamber
at <1°C. Working Paper No. 21, U. S. Environmental Protec-
tion Agency, Arctic Environmental Reaearch Station, College,
Alaska, 1973. 56 pp.
Grainge, 3. W., 3. K. Greenwood and 3. W. Shaw. Lagoon Sewage
Treatment for the Arctic and Subarctic. Presented at the
Environmental Protection Agency Technology Transfer Seminar,
Anchorage, Alaska. March 28-29, 1972.
Hiatt, A. L. Phase Isolation Helps Oxidation Pond Meet EPA 1977
Discharge Requirements. Water and Sewage Works 122,
12:42-43- 1975.
Horn, L. W. Chlorination of Waste Pond Effluents. In: Second
International Symposium for Waste Treatment Lagoons.
Univesity of Kansas, Lawrence, Kansas, 1970. pp. 151-158.
Hunter, 3ohn S. and 3ohn C. Ward. Part I - The Effects of Water
Temperature and Elevation Upon Aeration, The Mechanism of
Waste Treatment at Low Tempera tue - Part B: Sanitary
Engineering, OWRR Project No. A-007-COLO , Office of Water
Resources Research, U. S. Department of the Interior,
Washington, D. C., August 1972.
Kuentzal, L. E. Bacteria, Carbon Dioxide, and Algal Blooms.
3ournal Water Pollution Control Federation 41:1734-1747,
1969.
McKinney, R. E., 3. N. Dornbush and 3. W. Vennes. Waste Treat-
ment Lagoons - State of the Art. 17090 EHX. Prepared for
Office of Research and Monitoring, Environmental Protection
Agency, Washington, D. C., 1971.
Muller, 3. A. and W. 3. Su . Benthal Oxygen Demands and Leaching
Rates of Treated Sludges. 3ournal of the Water Pollution
Control Federation 44:2303-2315, 1972.
173
-------
Murphy, K. L. and A. F. Wilson. Characterization of Mixing in
Aerated Lagoons. 3. of the Sanitary Engineering Div . ,
Proceedings of the American Society of Civil Engineers
100:1105-1117, 1974.
Middlebrooks, E. 3., A. 3. Panagiotou, and H. K. Williford.
Sludge Accumulation in Municipal Sewage Lagoons. Water and
Sewage Works 112, 2:63-67, 1965.
Oswald, W. 3. Advances in Anaerobic Pond Design. In: Advances
in Water Quality Improvement, E. F. Gloyna and W. W. Ecken-
felder, 3r., eds. University of Texas Press, Austin and
London, 1968. pp. 409-426.
Oswald, W. 3. Fundamental Factors in Stabilization Pond Design.
In: Proceedings, Third Conference on Biological Waste
Treatment, Manhattan College, New York, 1960.
Oswald, W. 3., A. Her on and M. D. Zabat. Designing Waste Ponds
to Meet Water Quality Criteria. In: Second International
Symposium for Waste Treatment Lagoons, R. E. McKinney, ed.
University of Kansas, Lawrence, Kansas, 1970.
Penman, A., G. E. Burns, R. M. Girling, A. R. Pick, and
D. W. Van Es. Evaluation of Aerated Lagoons in Metropolitan
Winnipeg. Waterworks and Waste Disposal Division,
Metropolitan Corp. of Greater Winnipeg, March 1970.
Pfeffer, 3ohn T. Evaluation of Aerator Capabilities for
Wastewater Treatment. Tappi, 52, 1652, 1969.
Pierce, D. M. Performance of Raw Waste Stabilization Lagoons in
Michigan with Long Period Storage Before Discharge. In:
E. J. Middlebrooks, D. H. Falkenberg, R. F. Lewis, and
D. J. Enreth, ed. Upgrading Wastewater Stabilization Ponds
to Meet New Discharge Standards. Utah Water Research
Laboratory, Utah State Univ., Logan, Utah, 1974.
Pohl, E. F. A Rational Approach to the Design of Aerated
Lagoons. Alaska District, U.S. Army Corps of Engineers, An-
chorage, Alaska, 1967.
Pohl, Edward F. A Rational Approach to the Design of Aerated
Lagoons. Proceedings 2nd International Symposium for Waste
Treatment Lagoons. University of Kansas, June 1970. p 231.
Reid, L. C., 3r. Design and Operation Considerations for Aerated
Lagoons in the Arctic and Subarctic. Report No. 102. Arc-
tic Health Research Center, Environmental Health Service,
U.S. Public Health Service, DHEW, College, Alaska, 1970.
174
-------
Reid, L. C., Jr. Design and Operation of Aerated Lagoons for the
Arctic and Subarctic. Presented at the Environmental
Protection Agency Technology Transfer Design Seminar, An-
chorage, Alaska, April 9-10, 1975.
Rubel, 3. and D. R. Gray. Stabilization ponds in the Subarctic.
Construction Engineers, Eielson Air Force Base, Alaska,
1965.
Sawyer, Clair N., and Perry L. McCarty. Chemistry for Sanitary
Engineers. McGraw-Hill Book Co., 1967. p. 405.
Slanetz, L. W., Clara H. Bartley, T. G. Metcalf, and R. Nesman.
Survival of Enteric Bacteria and Viruses in Municipal Sewage
Lagoons. In: Proceedings 2nd International Symposium for
Waste Treatment Lagoons. University of Kansas, Lawrence,
Kansas, 1970.
Smith, Daniel W. Modeling Oxygen Transfer in Diffused Aeration
Tanks. Dissertation submitted in partial fulfillment of re-
guirements for the degree of Doctor of Philosophy, Univer-
sity of Kansas, July 1970.
Standard Methods for the Examination of Water and Wastewater.
13th Edition, American Public Health Association, 1740
Broadway, New York, 1965, 1971.
Thirumurthi, D. Design Principles of Waste Stabilization Ponds.
Journal of the Sanitary Engineering Div . , Proceedings of the
American Society of Civil Engineers. 95:311-330, 1969.
Thirumurthi, D. Design Criteria for Waste Stabilization Ponds.
Journal of the Water Pollution Control Federation.
46:2094-2106, 1974.
Thon , J. Oxygen Transfer Rate Determination on an Aer-Hydraulics
'Bubble Gun' Aeration System at the Brampton Pilot Plant.
Ontario Water Resources Commission, November 1964.
Vennes, J. W. and 0. 0. Olson. Microbiologic Indicators of the
Efficiency of an Aerated Continuous-Discharge, Sewage Lagoon
in Northern Climates. In: International Symposium on Water
Pollution Control in Cold Climates. University of Alaska,
College, Alaska, 1970. pp. 286-311.
Vesilind, P. A. Treatment and Disposal of Wastewater Sludges.
Ann Arbor Science Publishers, Inc., Ann Arbor, Michigan,
1975. 236 pp.
White, G. C. Handbook of Chlorination. Van Nostrand Reinhold
Co . , New York , 1972. 744 pp.
175
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-6nn/3-7q-nn3
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Performance of Aerated Lagoons in Northern Climates
5. REPORT DATE
January 1979
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
C.D. Christiansen and H.J. Coutts
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Arctic Environmental Research Station
U.S. Environmental Protection Agency
College, Alaska 99701
10. PROGRAM ELEMENT NO.
1AA602
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Corvallis Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Corvallis, Oregon 97330
13. TYPE OF REPORT AND PERIOD COVERED
in-house final
14. SPONSORING AGENCY CODE
EPA/600/02
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Studies of cold climate aerated lagoons conducted by the Arctic Environmental Research
Station, Fairbanks, Alaska are reported. Conclusions are based on these studies,
observations of full scale aerated lagoons operating in Alaska and reports on lagoons
in the northern tier of the United States and Canada.
Biological processes which occur in facultative aerated lagoons are reviewed and the
performance of cold climate aerated lagoons is examined. Winter and summer performance
is compared, and general criteria for the design of cold climate lagoons is presented.
Sample calculations for predicting the performance of aerated lagoons are also shown.
These calculations are based on the complete mix equation for aerated lagoon design
and on the results of the data analysis presented in this report. The information
presented indicates that lagoons can be designed or upgraded to meet P.L. 92-500
secondary standards. This may be done by increasing the number of cells in series,
by reducing short circuiting and through the use of a polishing pond. It is shown
that additional cells in series, for a given detention time, will increase the BOD
removal efficiency of a lagoon.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
aerated lagoons
cold climate
i. DISTRIBUTION STATEMENT
Release unlimited
19. SECURITY CLASS (This Report I
unclassified
21. NO. OF PAGES
188
20. SECURITY CLASS (This page)
unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77)
176
•frGPO 697-484
------- |